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  • 1.
    Abdi, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Numerical Investigation of Latent Thermal Storage in a Compact Heat Exchanger Using Mini-Channels2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 13, p. 5985-, article id 5985Article in journal (Refereed)
    Abstract [en]

    This paper aims to numerically investigate the thermal enhancement of a latent thermal energy storage component with mini-channels as air passages. The investigated channels in two sizes of internal air passages (channel-1 with d(h) = 1.6 mm and channel-2 with d(h) = 2.3 mm) are oriented vertically in a cuboid of 0.15 x 0.15 x 0.1 m(3) with RT22 as the PCM located in the shell. The phase change is simulated with a fixed inlet temperature of air, using ANSYS Fluent 19.5, with a varying number of channels and a ranging air flow rate entering the component. The results show that the phase change power of the LTES improves with by increasing the number of channels at the cost of a decrease in the storage capacity. Given a constant air flow rate, the increase in the heat transfer surface area of the increased number of channels dominates the heat transfer coefficient, thus increasing the mean heat transfer rate (UA). A comparison of the channels shows that the thermal performance depends largely on the area to volume ratio of the channels. The channel type two (channel-2) with a slightly higher area to volume ratio has a slightly higher charging/discharging power, as compared to channel type one (channel-1), at a similar PCM packing factor. Adding fins to channel-2, doubling the surface area, improves the mean UA values by 15-31% for the studied cases. The variation in the total air flow rate from 7 to 24 L/s is found to have a considerable influence, reducing the melting time by 41-53% and increasing the mean UA values within melting by 19-52% for a packing factor range of 77.4-86.8%. With the increase in the air flow rate, channel type two is found to have considerably lower pressure drops than channel type one, which can be attributed to its higher internal hydraulic diameter, making it superior in terms of achieving a relatively similar charging/discharging power in exchange for significantly lower fan power. Such designs can further be optimized in terms of pressure drop in future work, which should also include an experimental evaluation.

  • 2.
    Ahmad, Sarosh
    et al.
    Govt Coll Univ Faisalabad, Dept Elect Engn & Technol, Faisalabad 38000, Pakistan.;Univ Carlos III Madrid, Dept Signal Theory & Commun, Madrid 28911, Spain..
    Manzoor, Bilal
    Univ Engn & Technol UET, Dept Telecom Engn, Taxila 47050, Pakistan..
    Paracha, Kashif Nisar
    Govt Coll Univ Faisalabad, Dept Elect Engn & Technol, Faisalabad 38000, Pakistan..
    Haider, Sajjad
    King Saud Univ, Coll Engn, Chem Engn Dept, POB 800, Riyadh 11421, Saudi Arabia..
    Liaqat, Maryam
    Univ Okara UO, Dept Phys, Okara 56300, Pakistan..
    Al-Gburi, Ahmed Jamal Abdullah
    Univ Tekn Malaysia Melaka UTeM, Ctr Telecommun Res & Innovat CeTRI, Dept Elect & Comp Engn FKEKK, Durian Tungal 76100, Malaysia..
    Ghaffar, Adnan
    Auckland Univ Technol, Dept Elect & Elect Engn, Auckland 1010, New Zealand..
    Alibakhshikenari, Mohammad
    Univ Carlos III Madrid, Dept Signal Theory & Commun, Madrid 28911, Spain..
    Dalarsson, Mariana
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering.
    A Wideband Bear-Shaped Compact Size Implantable Antenna for In-Body Communications2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 6, p. 2859-, article id 2859Article in journal (Refereed)
    Abstract [en]

    Biomedical implantable antennas play a vital role in medical telemetry applications. These types of biomedical implantable devices are very helpful in improving and monitoring patients' living situations on a daily basis. In the present paper, a miniaturized footprint, thin-profile bear-shaped in-body antenna operational at 915 MHz in the industrial, scientific, and medical (ISM) band is proposed. The design is a straightforward bear-shaped truncated patch excited by a 50-Omega coaxial probe. The radiator is made up of two circular slots and one rectangular slot at the feet of the patch, and the ground plane is sotted to achieve a broadsided directional radiation pattern, imprinted on a Duroid RT5880 roger substrate with a typical 0.254-mm thickness (epsilon(r) = 2.2, tan delta = 0.0009). The stated antenna has a complete size of 7 mm x 7 mm x 0.254 mm and, in terms of guided wavelength, of 0.027 lambda(g) x 0.027 lambda(g) x 0.0011 lambda(g). When operating inside skin tissues, the antenna covers a measured bandwidth from 0.86 GHz to 1.08 GHz (220 MHz). The simulations and experimental outcomes of the stated design are in proper contract. The obtained results show that the calculated specific absorption rate (SAR) values inside skin of over 1 g of mass tissue is 8.22 W/kg. The stated SAR values are lower than the limitations of the federal communications commission (FCC). Thus, the proposed miniaturized antenna is an ultimate applicant for in-body communications.

  • 3.
    Alex-Amor, Antonio
    et al.
    Univ Politecn Madrid, Informat Proc & Telecommun Ctr, E-28040 Madrid, Spain.;Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18071 Granada, Spain..
    Valerio, Guido
    Sorbonne Univ, CNRS, Lab Genie Elect & Elect Paris, F-75252 Paris, France.;Univ Paris Saclay, Cent Supelec, CNRS, Lab Genie Elect & Elect Paris, F-91192 Gif Sur Yvette, France..
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, Microwaves Grp, Dept Appl Phys 1, Escuela Tecn Super Ingn Informat, E-41012 Seville, Spain..
    Padilla, Pablo
    Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18071 Granada, Spain..
    Fernandez-Gonzalez, Jose M.
    Univ Politecn Madrid, Informat Proc & Telecommun Ctr, E-28040 Madrid, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Wave Propagation in Periodic Metallic Structures with Equilateral Triangular Holes2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 5, article id 1600Article in journal (Refereed)
    Abstract [en]

    This paper studies wave propagation in a periodic parallel-plate waveguide with equilateral triangular holes. A mode-matching method is implemented to analyze the dispersion diagram of the structure possessing glide and mirror symmetries. Both structures present an unexpected high degree of isotropy, despite the triangle not being symmetric with respect to rotations of 90 degrees. We give some physical insight on the matter by carrying out a modal decomposition of the total field on the hole and identifying the most significant modes. Additionally, we demonstrate that the electrical size of the triangular hole plays a fundamental role in the physical mechanism that causes that isotropic behavior. Finally, we characterize the influence of the different geometrical parameters that conform the unit cell (period, triangle size, hole depth, separation between metallic plates). The glide-symmetric configuration offers higher equivalent refractive indexes and widens the stopband compared to the mirror-symmetric configuration. We show that the stopband is wider as the triangle size is bigger, unlike holey structures composed of circular and elliptical holes where an optimal hole size exists.

  • 4.
    Alharbi, Abdullah G.
    et al.
    Jouf Univ, Fac Engn, Dept Elect Engn, Sakaka 42421, Saudi Arabia..
    Rafique, Umair
    Sapienza Univ Rome, Dept Informat Engn Elect & Telecommun, I-00184 Rome, Italy..
    Ullah, Shakir
    Univ Engn & Technol, Telecommun Engn Dept, Mardan 23200, Pakistan..
    Khan, Salahuddin
    King Saud Univ, Coll Engn, POB 800, Riyadh 11421, Saudi Arabia..
    Abbas, Syed Muzahir
    Macquarie Univ, Fac Sci & Engn, Sch Engn, Sydney, NSW 2109, Australia..
    Ali, Esraa Mousa
    Amman Arab Univ, Fac Aviat Sci, Amman 11953, Jordan..
    Alibakhshikenari, Mohammad
    Univ Carlos III Madrid, Dept Signal Theory & Commun, Madrid 28911, Spain..
    Dalarsson, Mariana
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering.
    Novel MIMO Antenna System for Ultra Wideband Applications2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 7, article id 3684Article in journal (Refereed)
    Abstract [en]

    The design of a 4 x 4 MIMO antenna for UWB communication systems is presented in this study. The single antenna element is comprised of a fractal circular ring structure backed by a modified partial ground plane having dimensions of 30 x 30 mm(2). The single antenna element has a wide impedance bandwidth of 9.33 GHz and operates from 2.67 GHz to 12 GHz. Furthermore, the gain of a single antenna element increases as the frequency increases, with a peak realized gain and antenna efficiency of 5 dBi and >75%, respectively. For MIMO applications, a 4 x 4 array is designed and analyzed. The antenna elements are positioned in a plus-shaped configuration to provide pattern as well as polarization diversity. It is worth mentioning that good isolation characteristics are achieved without the utilization of any isolation enhancement network. The proposed MIMO antenna was fabricated and tested, and the results show that it provides UWB response from 2.77 GHz to over 12 GHz. The isolation between the antenna elements is more than 15 dB. Based on performance attributes, it can be said that the proposed design is suitable for UWB MIMO applications.

  • 5.
    Arena, Maurizio
    et al.
    Magnaghi Aeronaut MA Grp Co, Engn & Res Unit, Via Galileo Ferraris 76, I-80146 Naples, NA, Italy..
    Mehta, Bharat
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties. Chalmers Univ Technol, Dept Ind & Mat Sci, Rannvagen 2A, S-41296 Gothenburg, Sweden.
    Tirelli, Tommaso
    Aidro S r l, I-21020 Taino, VA, Italy..
    Ambrogiani, Paolo
    Aidro S r l, I-21020 Taino, VA, Italy..
    Castaldo, Martina
    Magnaghi Aeronaut MA Grp Co, Engn & Res Unit, Via Galileo Ferraris 76, I-80146 Naples, NA, Italy..
    Bengtsson, Sven
    Chalmers Univ Technol, Dept Ind & Mat Sci, Rannvagen 2A, S-41296 Gothenburg, Sweden.;Hoganas AB, Bruksgatan 35, SE-26383 Hoganas, Sweden..
    Nyborg, Lars
    Chalmers Univ Technol, Dept Ind & Mat Sci, Rannvagen 2A, S-41296 Gothenburg, Sweden..
    Novel Aluminum Alloy Tailored for Additive Manufacturing: Structural Characterization and Qualification Perspectives2024In: Applied Sciences, E-ISSN 2076-3417, Vol. 14, no 11, article id 4647Article in journal (Refereed)
    Abstract [en]

    Featured Application The paper demonstrates key structural characteristics of a novel aluminum alloy conceived for AM-based components in the aviation frame.Abstract The recent advances achieved in additive manufacturing (AM) technology demonstrate the potential to realize customized metal components, ensuring weight reduction opportunities. These benefits make AM attractive for high-cost aerospace applications, especially where high geometric complexity is required. In the context of an EU research scenario, the H2020 MANUELA (Additive Manufacturing Using Metal Pilot Line) project promotes the development of new technologies for design optimization by enabling the application of novel materials in AM. This paper illustrates recent advances in a new aluminum alloy (Al-HS1) with high strength emphasizing all of the characterization steps at the coupon level. This material has been employed in the re-engineering of a conventional hydraulic manifold using a powder bed fusion-laser beam (PBF-LB) process. Both the simulations and structural tests allowed for proving its compliance and technological maturity with industrial standards and applicable airworthiness requirements.

  • 6.
    Arnberg, Philip
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Petersson, Oscar Barreira
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Dahlberg, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    High Refractive Index Electromagnetic Devices in Printed Technology Based on Glide-Symmetric Periodic Structures2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 9, article id 3216Article in journal (Refereed)
    Abstract [en]

    We demonstrate the beneficial effects of introducing glide symmetry in a two-dimensional periodic structure. Specifically, we investigate dielectric parallel plate waveguides periodically loaded with Jerusalem cross slots in three configurations: conventional, mirror- and glide-symmetric. Out of these three configurations, it is demonstrated that the glide-symmetric structure is the least dispersive and has the most isotropic response. Furthermore, the glide-symmetric structure provides the highest effective refractive index, which enables the realization of a broader range of electromagnetic devices. To illustrate the potential of this glide-symmetric unit cell, a Maxwell fish-eye lens is designed to operate at 5 GHz. The lens is manufactured in printed circuit board technology. Simulations and measurements are in good agreement and a measured peak transmission coefficient of -0.5 dB is achieved.

  • 7.
    Blachucki, Wojciech
    et al.
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Wach, Anna
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Czapla-Masztafiak, Joanna
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Delcey, Mickael G
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Arrell, Christopher
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Fanselow, Rafal
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Juranic, Pavle
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Lundberg, Marcus
    Uppsala Univ, Dept Chem, S-75120 Uppsala, Sweden..
    Milne, Christopher
    European XFEL GmbH, D-22869 Schenefeld, Germany..
    Sa, Jacinto
    Uppsala Univ, Dept Chem, S-75120 Uppsala, Sweden.;Polish Acad Sci, Inst Phys Chem, PL-01224 Warsaw, Poland..
    Szlachetko, Jakub
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Approaching the Attosecond Frontier of Dynamics in Matter with the Concept of X-ray Chronoscopy2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 3, article id 1721Article in journal (Refereed)
    Abstract [en]

    Featured Application Herein, an innovative methodology, called X-ray chronoscopy, is proposed for exploration of ultrafast processes in matter with attosecond precision using current XFEL sources. The method is based on measuring the change in an X-ray pulse temporal profile induced by interaction with a medium. X-ray free electron lasers (XFELs) have provided scientists opportunities to study matter with unprecedented temporal and spatial resolutions. However, access to the attosecond domain (i.e., below 1 femtosecond) remains elusive. Herein, a time-dependent experimental concept is theorized, allowing us to track ultrafast processes in matter with sub-fs resolution. The proposed X-ray chronoscopy approach exploits the state-of-the-art developments in terahertz streaking to measure the time structure of X-ray pulses with ultrahigh temporal resolution. The sub-femtosecond dynamics of the saturable X-ray absorption process is simulated. The employed rate equation model confirms that the X-ray-induced mechanisms leading to X-ray transparency can be probed via measurement of an X-ray pulse time structure.

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  • 8.
    Bobyr, Serhii
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures. Iron and Steel Institute of Z. I. Nekrasov, National Academy of Sciences of Ukraine, 49107 Dnipro, Ukraine.
    Krot, Pavlo
    Faculty of Geoengineering, Mining and Geology, Wroclaw University of Science and Technology, Wrocław, 50-370, Poland.
    Parusov, Eduard
    Iron and Steel Institute of Z. I. Nekrasov, National Academy of Sciences of Ukraine, 49107 Dnipro, Ukraine;.
    Golubenko, Tetiana
    Iron and Steel Institute of Z. I. Nekrasov, National Academy of Sciences of Ukraine, 49107 Dnipro, Ukraine;.
    Baranovs’ka, Olena
    Iron and Steel Institute of Z. I. Nekrasov, National Academy of Sciences of Ukraine, 49107 Dnipro, Ukraine;.
    Increasing the Wear Resistance of Structural Alloy Steel 38CrNi3MoV Subjected to Isothermal Hardening and Deep Cryogenic Treatment2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 16, article id 9143Article in journal (Refereed)
    Abstract [en]

    In the production of critical parts for various machines and mechanisms, expensive structural steels are used alloyed with chromium, nickel, molybdenum, and vanadium. In practice, the wear resistance of parts, especially under severe operating conditions, may be insufficient due to uneven microstructure and the content of retained austenite. Therefore, increasing the operational stability of various products made of alloy steels is an important task. The purpose of this work is to investigate the effect of isothermal hardening from the intermediate (γ+α)-area and the duration of deep cryogenic treatment on the structure formation and frictional wear resistance of 38CrNi3MoV steel. The isothermal hardening promotes the formation of the required multiphase microstructure of 38CrNi3MoV steel. The influence of the duration of deep cryogenic treatment on the microhardness, amount of retained austenite, fine structure parameters, and friction wear of 38CrNi3MoV steel are established. Complex heat treatment of 38CrNi3MoV steel, according to the proposed mode, makes it possible to achieve a significant decomposition of retained austenite to martensite, which leads to an increase in frictional wear resistance of ~58%.

  • 9.
    Cha, Kyeong-Ju
    et al.
    Korea Univ, Dept Electromech Engn, Sejong Si 30019, South Korea..
    Lee, Jung-Bum
    Korea Univ, Dept Electromech Engn, Sejong Si 30019, South Korea..
    Özger, Mustafa
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS.
    Lee, Woong-Hee
    Korea Univ, Dept Control & Instrumentat Engn, Sejong Si 30019, South Korea..
    When Wireless Localization Meets Artificial Intelligence: Basics, Challenges, Synergies, and Prospects2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 23, article id 12734Article, review/survey (Refereed)
    Abstract [en]

    The rapid development of information communication and artificial intelligence (AI) technology is driving innovation in various new application fields such as autonomous driving, augmented reality, and the metaverse. In particular, the advancement of wireless localization technology plays a great role in these cutting-edge technologies. However, traditional wireless localization systems rely on the global navigation satellite system (GNSS), which is ineffective in indoor or underground environments. To overcome this issue, indoor positioning systems (IPS) have gained attention, and various localization techniques utilizing wireless communication were studied. Subsequently, AI technologies are improving the performance of wireless localization and addressing problems that were previously difficult to solve. In this paper, we summarize wireless localization techniques and define the factors that impede their performance. Furthermore, we categorize AI algorithms and present examples of how they can be used to address these hindering factors. Finally, we propose open research directions and prospects for AI-assisted wireless localization.

  • 10.
    Chen, DeJiu
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Su, Peng
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Ottikkutti, Suranjan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Embedded Control Systems.
    Vartholomeos, Panagiotis
    Tahmasebi, Kaveh Nazem
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Embedded Control Systems.
    Karamousadakis, Michalis
    Analyzing Dynamic Operational Conditions of Limb Prosthetic Sockets with a Mechatronics-Twin Framework2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 3, p. 986-986Article in journal (Refereed)
    Abstract [en]

    Lower limb prostheses offer a solution to restore the ambulation and self-esteem of amputees. One key component is the prosthetic socket that serves as the interface between prosthetic device and amputee stump and thereby has a wide range of impacts on efficient fitting, appropriate load transmission, operational stability, and control. For the design and optimization of a prosthetic socket, an understanding of the actual intra-socket operational conditions becomes therefore necessary. This is however a difficult task due to the inherent complexity and restricted observability of socket operation. In this study, an innovative mechatronics-twin framework that integrates advanced biomechanical models and simulations with physical prototyping and dynamic operation testing for effective exploration of operational behaviors of prosthetic sockets with amputees is proposed. Within this framework, a specific Stewart manipulator is developed to enable dynamic operation testing, in particular for a well-managed generation of dynamic intra-socket loads and behaviors that are otherwise difficult to observe or realize with the real amputees. A combination of deep learning and Bayesian Inference algorithms is then employed for analyzing the intra-socket load conditions and revealing possible anomalous. 

  • 11.
    Cheng, Xiaogang
    et al.
    Nanjing Univ Posts & Telecommun, Coll Telecommun & Informat Engn, Nanjing 210003, Jiangsu, Peoples R China.;Swiss Fed Inst Technol, Comp Vis Lab, CH-8092 Zurich, Switzerland..
    Yang, Bin
    Xian Univ Architecture & Technol, Sch Bldg Serv Sci & Engn, Xian 710055, Shaanxi, Peoples R China.;Umea Univ, Dept Appl Phys & Elect, S-90187 Umea, Sweden..
    Tan, Kaige
    KTH.
    Isaksson, Erik
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID.
    Li, Liren
    Nanjing Tech Univ, Sch Comp Sci & Technol, Nanjing 211816, Jiangsu, Peoples R China..
    Hedman, Anders
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID.
    Olofsson, Thomas
    Umea Univ, Dept Appl Phys & Elect, S-90187 Umea, Sweden..
    Li, Haibo
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID. Nanjing Univ Posts & Telecommun, Coll Telecommun & Informat Engn, Nanjing 210003, Jiangsu, Peoples R China.
    A Contactless Measuring Method of Skin Temperature based on the Skin Sensitivity Index and Deep Learning2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 7, article id 1375Article in journal (Refereed)
    Abstract [en]

    Featured Application The NISDL method proposed in this paper can be used for real time contactless measuring of human skin temperature, which reflects human body thermal comfort status and can be used for control HVAC devices. Abstract In human-centered intelligent building, real-time measurements of human thermal comfort play critical roles and supply feedback control signals for building heating, ventilation, and air conditioning (HVAC) systems. Due to the challenges of intra- and inter-individual differences and skin subtleness variations, there has not been any satisfactory solution for thermal comfort measurements until now. In this paper, a contactless measuring method based on a skin sensitivity index and deep learning (NISDL) was proposed to measure real-time skin temperature. A new evaluating index, named the skin sensitivity index (SSI), was defined to overcome individual differences and skin subtleness variations. To illustrate the effectiveness of SSI proposed, a two multi-layers deep learning framework (NISDL method I and II) was designed and the DenseNet201 was used for extracting features from skin images. The partly personal saturation temperature (NIPST) algorithm was use for algorithm comparisons. Another deep learning algorithm without SSI (DL) was also generated for algorithm comparisons. Finally, a total of 1.44 million image data was used for algorithm validation. The results show that 55.62% and 52.25% error values (NISDL method I, II) are scattered at (0 degrees C, 0.25 degrees C), and the same error intervals distribution of NIPST is 35.39%.

  • 12.
    De Colle, Mattia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Kielman, Ross
    KTH.
    Karlsson, Andreas
    Swedish Museum Nat Hist, SE-10405 Stockholm, Sweden..
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Study of the Dissolution of Stainless-Steel Slag Minerals in Different Acid Environments to Promote Their Use for the Treatment of Acidic Wastewaters2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 24, article id 12106Article in journal (Refereed)
    Abstract [en]

    Several stainless-steel slags have been successfully employed in previous studies as substitutes for lime in the treatment of industrial acidic wastewaters. This study deepens the knowledge of such application, by analyzing the neutralizing capacity of different slags related to their mineral compositions. To do so, firstly the chemical and mineral compositions of all the slag samples are assessed. Then, 0.5 g, 1 g, 2 g of each slag and 0.25 g and 0.5 g of lime are used to neutralize 100 g of 0.1 M HCl or HNO3 solutions. After the has neutralization occurred, the solid residues are extracted and analyzed using XRD spectroscopy. Then, the solubility of the minerals is assessed and ranked, by comparing the XRD spectra of the residues with the obtained pH values. The results show that minerals such as dicalcium silicate and bredigite are highly soluble in the selected experimental conditions, while minerals such as merwinite and akermanite, only partially. Moreover, Al-rich slags seem to perform poorly due to the formation of hydroxides, which generate extra protons. However, when the weight of slag is adequately adjusted, Al-rich slags can increase the pH values to higher levels compared to the other studied slags.

  • 13.
    Dimitropoulos, Dimitrios
    et al.
    Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Wang, Xiongfei
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems. Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark.
    Blaabjerg, Frede
    Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Stability Analysis in Multi-VSC (Voltage Source Converter) Systems of Wind Turbines2024In: Applied Sciences, E-ISSN 2076-3417, Vol. 14, no 8, article id 3519Article in journal (Refereed)
    Abstract [en]

    In this paper, a holistic nonlinear state-space model of a system with multiple converters is developed, where the converters correspond to the wind turbines in a wind farm and are equipped with grid-following control. A novel generalized methodology is developed, based on the number of the system's converters, to compute the equilibrium points around which the model is linearized. This is a more solid approach compared with selecting operating points for linearizing the model or utilizing EMT simulation tools to estimate the system's steady state. The dynamics of both the inner and outer control loops of the power converters are included, as well as the dynamics of the electrical elements of the system and the digital time delay, in order to study the dynamic issues in both high- and low-frequency ranges. The system's stability is assessed through an eigenvalue-based stability analysis. A participation factor analysis is also used to give an insight into the interactions caused by the control topology of the converters. Time domain simulations and the corresponding frequency analysis are performed in order to validate the model for all the control interactions under study.

  • 14.
    Du, Jianbiao
    et al.
    Harbin Univ Sci & Technol, Sch Mech & Power Engn, Harbin 150080, Heilongjiang, Peoples R China..
    Yue, Caixu
    Harbin Univ Sci & Technol, Sch Mech & Power Engn, Harbin 150080, Heilongjiang, Peoples R China..
    Liu, Xianli
    Harbin Univ Sci & Technol, Sch Mech & Power Engn, Harbin 150080, Heilongjiang, Peoples R China..
    Liang, Steven Y.
    Georgia Inst Technol, Atlanta, GA 30332 USA..
    Wang, Lihui
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Gao, Haining
    Harbin Univ Sci & Technol, Sch Mech & Power Engn, Harbin 150080, Heilongjiang, Peoples R China..
    Li, Hengshuai
    Harbin Univ Sci & Technol, Sch Mech & Power Engn, Harbin 150080, Heilongjiang, Peoples R China..
    Transient Temperature Field Model of Wear Land on the Flank of End Mills: A Focus on Time-Varying Heat Intensity and Time-Varying Heat Distribution Ratio2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 8, article id 1698Article in journal (Refereed)
    Abstract [en]

    Modelling methods for the transient temperature field of wear land on the flank of end mills have been proposed to address the challenges of inaccurate prediction in the temperature field of end mills during the high-speed peripheral milling of Ti6Al4V that is a titanium alloy. A transient temperature rise model of wear land on the flank of end mills was constructed under the influence of heat sources in the primary shearing zone (PSZ), rake-chip zone (RCZ), flank-workpiece zone (FWZ), and dissipating heat source. Then the transient temperature field model of wear land on the flank of end mills was constructed. Finally, the transient temperature field model of wear land on the flank of end mills was constructed. Comparison of simulation result and experimental data verified the accuracy of the model. In sum, the proposed model may provide a temperature model support for future studies of flank wear rate in end mill modeling.

  • 15. Forquin, P.
    et al.
    Saadati, Mahdi
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics.
    Saletti, D.
    Lukic, B.
    Schiaffini, F.
    Weddfelt, K.
    Larsson, Per-Lennart
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics.
    Investigation of the Mechanical Behaviour of Lingulid Sandstone Emphasising the Influence from Pre-Existing Structural Defects, Part 1: Model Identification Based on Static Experiments2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 21, p. 10806-, article id 10806Article in journal (Refereed)
    Abstract [en]

    A constitutive model able to describe both tensile damage and plastic deformation under confinement is a prerequisite to numerically simulate the behaviour of sandstone rock under an impact loading induced in a percussive drilling process. Therefore, model identification under both tensile and high confinement states is needed. In the present work, an experimental investigation was carried out in order to determine the mechanical properties of a sandstone rock for the purpose of advanced constitutive model identification. Different testing methods were used in quasistatic and dynamic loading regimes. This first part of the study is dedicated to static experiments, whereby three-point bend tests were first performed to evaluate the quasistatic tensile strength of the rock and its distribution by employing the Weibull statistics. Secondly, direct compression tests were conducted to evaluate the stiffness and strength in an unconfined condition. Afterwards, quasioedometric compression (QOC) tests were carried out in order to obtain the deviatoric and volumetric behaviours of the material as a function of the hydrostatic pressure (up to 375 MPa). In these QOC tests, the metallic confinement cell was instrumented with strain gauges to deduce the state of the stress and strain within the sample. A linear volumetric response along with a continuous increase of strength with the level of hydrostatic pressure was observed. This experimental work points out that, under unconfined loading (three-point bending and uniaxial compression), pre-existing structural defects play a major role leading to a highly scattered behaviour in terms of sample stiffness and ultimate applied load. On the other hand, under high confinement levels (QOC tests), beyond the nonlinear response of the curve foot, the influence from structural defects was observed to be small. 

  • 16.
    Forquin, Pascal
    et al.
    Univ Grenoble Alpes, 3SR Lab, F-38041 Grenoble, France..
    Saadati, Mahdi
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics. Epiroc Rock Drills, S-70225 Örebro, Sweden..
    Saletti, Dominique
    Univ Grenoble Alpes, 3SR Lab, F-38041 Grenoble, France..
    Lukic, Bratislav
    Univ Grenoble Alpes, 3SR Lab, F-38041 Grenoble, France..
    Schiaffini, Federico
    Univ Grenoble Alpes, 3SR Lab, F-38041 Grenoble, France..
    Weddfelt, Kenneth
    Epiroc Rock Drills, S-70225 Örebro, Sweden..
    Larsson, Per-Lennart
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics.
    Investigation of the Mechanical Behaviour of Lingulid Sandstone Emphasizing the Influence from Pre-Existing Structural Defects-Part 2: Dynamic Testing and Numerical Modelling2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 22, p. 11621-, article id 11621Article in journal (Refereed)
    Abstract [en]

    In the present study, dynamic experiments are developed to investigate the induced damage modes when Lingulid sandstone is subjected to dynamic and impact loading. To do so, a series of spalling tests were carried out in order to investigate the material response at high strain tension rates. This illustrates how structural defects influence the wave propagation in the tested sample, the loading-rate, and the resulting tensile strength. In addition, edge-on-impact tests were performed using both open and sarcophagus configurations. An ultra-high-speed image recording system is used in an open configuration for time-resolved visualisation of damage. The sarcophagus configuration gives the opportunity to visually compare the state of the cracking pattern prior to and after the test. This experimental work points-out that the pre-existing structural defects play a major role on impact loading. This is because the opening of cracks in mode I and the sliding of cracks in mode II are favoured, and by also restricting the fragmentation of the material caused by less critical defects. Next, a numerical simulation, only involving the so-called KST model, is presented to highlight the loading that would be applied to the target in the absence of structural defects. It demonstrates that in such a situation, a wide network of radial cracks would be expected. Finally, a numerical study involving the KST-DFH model illustrates the influence of a structural defect on the amount of damage generated in the target.

  • 17.
    Frodeson, Stefan
    et al.
    Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    Lindén, Pär
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    Karlstad Univ, Dept Engn & Chem Sci, Chem Engn, SE-65188 Karlstad, Sweden..
    Berghel, Jonas
    Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    Compression of Biomass Substances-A Study on Springback Effects and Color Formation in Pellet Manufacture2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 20Article in journal (Refereed)
    Abstract [en]

    In order to increase the use of a variated raw material base for pellet production with a maintained density level, knowledge of the biomaterials' ability to counteract any springback effects is essential. In this study, the springback effects were investigated for single press produced pellets from cellulose, hemicelluloses, pectin, and two woods at different moisture contents. The change in pellet coloring was also tested through a spectrophotometer for both xylan and carboxymethyl cellulose (CMC) pellets. The results show that the density of xylan pellets is much higher than glucomannan, for both green and cured pellets, and that the length of the pellets, as well as springback contribution, differ between the hemicelluloses. The study also presents results showing that both xylan and CMC pellets have a mutually identical spectrum and that the changes in the structure of xylan are not only related to moisture content, but are also pressure-related. The study also postulates that the color difference of the xylan pellets is a result of physical changes in the structure, as opposed to being of a chemical nature.

  • 18.
    Ghanbarpour, Morteza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Mota-Babiloni, Adrian
    Univ Jaume 1, Dept Mech Engn & Construct, ISTENER Res Grp, Campus Riu Sec S-N, E-12071 Castellon de La Plana, Spain..
    Badran, Bassam E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Energy, Exergy, and Environmental (3E) Analysis of Hydrocarbons as Low GWP Alternatives to R134a in Vapor Compression Refrigeration Configurations2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 13, p. 6226-, article id 6226Article in journal (Refereed)
    Abstract [en]

    The phase-down of hydrofluorocarbons and substitution with low global warming potential values are consequences of the awareness about the environmental impacts of greenhouse gases. This theoretical study evaluated the energy and exergy performances and the environmental impact of three vapor compression system configurations operating with the hydrocarbons R290, R600a, and R1270 as alternatives to R134a. The refrigeration cycle configurations investigated in this study include a single-stage cycle, a cycle equipped with an internal heat exchanger, and a two-stage cycle with vapor injection. According to the results, the alternative hydrocarbon refrigerants could provide comparable system performance to R134a. The analysis results also revealed that using an internal heat exchanger or a flash tank vapor injection could improve the system's efficiency while decreasing the heating capacity. The most efficient configuration was the two-stage refrigeration cycle with vapor injection, as revealed by the exergy analysis. The environmental impact analysis indicated that the utilization of environmentally-friendly refrigerants and improving the refrigeration system's efficiency could mitigate equivalent CO2 emissions significantly. The utilization of hydrocarbons reduced the carbon footprint by 50%, while a 1% to 8% reduction could be achieved using the internal heat exchanger and flash tank vapor injection.

  • 19.
    Ghanbarpour, Morteza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Mota-Babiloni, Adrian
    Univ Jaume 1, Dept Mech Engn & Construct, ISTENER Res Grp, Campus Riu Sec S-N, E-12071 Castellon de La Plana, Spain..
    Badran, Bassam E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Theoretical Global Warming Impact Evaluation of Medium and High Temperature Heat Pumps Using Low GWP Refrigerants2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 15, article id 7123Article in journal (Refereed)
    Abstract [en]

    This study provides a global warming impact analysis of environmentally friendly refrigerants used as replacements for R134a and R245fa. R290, R1234yf, R1234ze(E), R513A and R450A are considered as refrigerants to replace R134a in medium temperature applications. For R245fa, there are five alternative refrigerants, R1224yd(Z), R600, R1336mzz(Z), R1233zd(E) and R1234ze(Z), which are selected for high-temperature applications. The analysis is done considering the emission factors in Brazil, Sweden, Canada and Poland. In Sweden and Brazil, the total equivalent warming impact per heating capacity of R134a is higher than its alternative refrigerants in medium temperature application, although R134a exhibits a higher coefficient of performance than its alternatives. In high-temperature applications, R1336mzz(Z) has the lowest total equivalent warming impact per heating capacity due to its higher coefficient of performance than other tested refrigerants. The highest total equivalent warming impact per heating capacity belongs to R245fa in all countries except in Poland, where R600 exhibits a higher value due to its lower coefficient of performance and the relatively higher emission factor in Poland compared to other selected countries. These results revealed that in addition to the global warming potential, the emission factor associated with the sources of electricity generation has a crucial impact on indirect emissions.

  • 20.
    Ghanbarpour, Morteza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Mota-Babiloni, Adrian
    Univ Jaume 1, ISTENER Res Grp, Dept Mech Engn & Construct, Campus Riu Sec S-N, E-12071 Castellon de La Plana, Spain..
    Makhnatch, Pavel
    Pamatek AB, S-17065 Solna, Sweden..
    Badran, Bassam E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Rogstam, Joergen
    EKA Energi & Kylanalys AB, Prastgardsgrand 4, S-12544 Alvsjo, Sweden..
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    ANN Modeling to Analyze the R404A Replacement with the Low GWP Alternative R449A in an Indirect Supermarket Refrigeration System2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 23, article id 11333Article in journal (Refereed)
    Abstract [en]

    Artificial neural networks (ANNs) have been considered for assessing the potential of low GWP refrigerants in experimental setups. In this study, the capability of using R449A as a lower GWP replacement of R404A in different temperature levels of a supermarket refrigeration system is investigated through an ANN model trained using field measurements as input. The supermarket refrigeration was composed of two indirect expansion circuits operated at low and medium temperatures and external subcooling. The results predicted that R449A provides, on average, a higher 10% and 5% COP than R404A at low and medium temperatures, respectively. Moreover, the cooling capacity was almost similar with both refrigerants in both circuits. This study also revealed that the ANN model could be employed to accurately predict the energy performance of a commercial refrigeration system and provide a reasonable judgment about the capability of the alternative refrigerant to be retrofitted in the system. This is very important, especially when the measurement data comes from field measurements, in which values are obtained under variable operating conditions. Finally, the ANN results were used to compare the carbon footprint for both refrigerants. It was confirmed that this refrigerant replacement could reduce the emissions of supermarket refrigeration systems.

  • 21.
    Hamawandi, Bejan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Ballikaya, Sedat
    Istanbul Univ, Dept Phys, TR-34320 Istanbul, Turkey..
    Batili, Hazal
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Roosmark, Viking
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Orlovska, Martina
    Slovak Univ Technol Bratislava, Dept Inorgan Mat, Bratislava 81237, Slovakia..
    Yusuf, Aminu
    Istanbul Univ Cerrahpasa, Dept Elec & Elec Engn, TR-34135 Istanbul, Turkey..
    Johnsson, Mats
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Szukiewicz, Rafal
    LUKASIEWICZ Res Network PORT Polish Ctr Technol D, Stablowicka 147, PL-54066 Wroclaw, Poland.;Univ Wroclaw, Inst Expt Phys, Maxa Borna 9, PL-50204 Wroclaw, Poland..
    Kuchowicz, Maciej
    LUKASIEWICZ Res Network PORT Polish Ctr Technol D, Stablowicka 147, PL-54066 Wroclaw, Poland.;Univ Wroclaw, Inst Expt Phys, Maxa Borna 9, PL-50204 Wroclaw, Poland..
    Toprak, Muhammet
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Facile Solution Synthesis, Processing and Characterization of n- and p-Type Binary and Ternary Bi-Sb Tellurides2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 3, article id 1178Article in journal (Refereed)
    Abstract [en]

    The solution synthesis route as a scalable bottom-up synthetic method possesses significant advantages for synthesizing nanostructured bulk thermoelectric (TE) materials with improved performance. Tuning the composition of the materials directly in the solution, without needing any further processing, is important for adjusting the dominant carrier type. Here, we report a very rapid (2 min) and high yield (>8 g/batch) synthetic method using microwave-assisted heating, for the controlled growth of Bi2-xSbxTe3 (x: 0-2) nanoplatelets. Resultant materials exhibit a high crystallinity and phase purity, as characterized by XRD, and platelet morphology, as revealed by SEM. Surface chemistry of as-made materials showed a mixture of metallic and oxide phases, as evidenced by XPS. Zeta-potential analysis exhibited a systematic change of isoelectric point as a function of the material composition. As-made materials were directly sintered into pellets by using spark plasma sintering process. TE performance of Bi2-xSbxTe3 pellets were studied, where the highest ZT values of 1.04 (at 440 K) for Bi2Te3 and 1.37 (at 523 K) for Sb2Te3 were obtained, as n- and p-type TE materials. The presented microwave-assisted synthesis method is energy effective, a truly scalable and reproducible method, paving the way for large scale production and implementation of towards large-area TE applications.

  • 22.
    He, Liang
    et al.
    Chongqing Jiaotong Univ, Natl & Local Joint Engn Lab Traff Civil Engn Mat, Chongqing 400074, Peoples R China..
    Zhou, Zhiguang
    Chongqing Jiaotong Univ, Natl & Local Joint Engn Lab Traff Civil Engn Mat, Chongqing 400074, Peoples R China..
    Ling, Fei
    Chongqing Jiaotong Univ, Natl & Local Joint Engn Lab Traff Civil Engn Mat, Chongqing 400074, Peoples R China..
    Alexiadis, Alessio
    Univ Birmingham, Sch Chem Engn, Birmingham B15 2TT, W Midlands, England..
    Van den Bergh, Wim
    Univ Antwerp, Fac Appl Engn, Groenenborgerlaan 171, B-2020 Antwerp, Belgium..
    Falchetto, Augusto Cannone
    Aalto Univ, Dept Civil Engn, Espoo 02150, Finland..
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Zhu, Jiqing
    Swedish Natl Rd & Transport Res Inst VTI, S-58195 Linköping, Sweden..
    Valentin, Jan
    Czech Tech Univ, Fac Civil Engn, Prague 16629, Czech Republic..
    Kowalski, Karol J.
    Warsaw Univ Technol, Fac Civil Engn, PL-00637 Warsaw, Poland..
    Zhang, Lei
    Harbin Inst Technol, Sch Transportat Sci & Engn, Harbin 150090, Peoples R China..
    A Coarse-Grained Molecular Model for Simulating Self-Healing of Bitumen2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 20, p. 10360-, article id 10360Article in journal (Refereed)
    Abstract [en]

    The longevity of asphalt pavements is a key focus of road engineering, which closely relates to the self-healing ability of bitumen. Our work aims to establish a CGMD model and matched force field for bitumen and break through the limitations of the research scale to further explore the microscopic mechanism of bitumen self-healing. In this study, a CGMD mapping scheme containing 16 kinds of beads is proposed, and the non-bond potential energy function and bond potential energy function are calculated based on all-atom simulation to construct and validate a coarse-grained model for bitumen. On this basis, a micro-crack model with a width of 36.6nm is simulated, and the variation laws of potential energy, density, diffusion coefficient, relative concentration and temperature in the process of bitumen self-healing are analyzed with the cracking rate parameter proposed to characterize the degree of bitumen crack healing. The results show that the computational size of the coarse-grained simulation is much larger than that of the all-atom, which can explain the self-healing mechanism at the molecular level. In the self-healing process, non-bonded interactions dominate the molecular movement, and differences in the decreased rate of diffusion among the components indicate that saturates and aromatics play a major role in self-healing. Meanwhile, the variations in crack rates reveal that healing time is inversely proportional to temperature. The impact of increasing temperature on reducing healing time is most obvious when the temperature approaches the glass transition temperature (300 K).

  • 23.
    He, Nan
    et al.
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Peoples R China..
    Guo, Tingbiao
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Peoples R China..
    Jin, Yi
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Peoples R China..
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Peoples R China..
    All-in-One Collimating Splitter Based on a Meta-Fiber Platform2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 7, article id 4603Article in journal (Refereed)
    Abstract [en]

    The use of array generators has become ubiquitous in various applications such as laser fabrication, face identification, and motion sensing. The Dammann grating, a diffractive optical element, is the mainstream approach for generating uniform spot arrays. However, its limited capability and the contradiction between the performance and the complexity of fabrication hinder its application. To address this issue, an all-in-one collimating splitter based on metasurfaces is theoretically proposed by synthesizing the phase of an inverse-optimized Dammann grating and a collimating lens. Leveraging both the diffraction effect of Dammann grating and the Fourier transformation of the collimating lens, the number of spot arrays can be largely increased with a single lenslet. The proposed design shows a large field of view of 62 degrees x 62 degrees ffi and a high uniformity of 1.29% in generating a spot array of 3 x 3 on a single-fiber platform, confirmed by both the scalar and full-wave simulation. Further, a larger spot array up to 15 x 15 is also derived in the far field by integrating the proposed metasurface on a 5 x 5 fiber array platform, confirmed by the scalar simulation. Our design may be transplanted to the vertical-cavity surface-emitting laser platform, and shows great potential in various applications including face identification and motion sensing.

  • 24.
    Huang, Qi
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Finite Element Analysis of Energy-Absorbing Floors for Reducing Head Injury Risk during Fall Accidents2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 24, article id 13260Article in journal (Refereed)
    Abstract [en]

    Featured Application: The results proposed a new approach to evaluate the protection effectiveness of energy-absorbing floors for fall-related injury prevention. Also, it could help to reduce the huge associated costs related to fall-related injuries among the children and elderly population. Energy-absorbing floor (EAF) has been proposed as one of several biomechanically effective strategies to mitigate the risk of fall-related injuries by decreasing peak loads and enhancing system energy absorption. This study aims to compare the protective capacity of four commercially available EAF products (Igelkott Floor, Kradal, SmartCells, and OmniSports) in terms of head impacts using the finite element (FE) method. The stress–strain curves acquired from mechanical tests were applied to material models in LS-Dyna. The established FE models were then validated using Hybrid III or hemispheric drop tests to compare the acceleration–time curves between experiments and simulations. Finally, the validated FE models were utilized to simulate a typical pedestrian fall accident scenario. It was demonstrated that EAFs can substantially reduce the peak forces, acceleration, and velocity changes during fall-related head impacts. Specifically, in the accident reconstruction scenario, SmartCells provided the largest reduction in peak linear acceleration and skull fracture risk, while Igelkott Floor provided the largest reduction in peak angular velocity and concussion risk. This performance was caused by different energy absorption mechanisms. Consequently, the results can contribute to supporting the implementation of EAFs and determine the effectiveness of various protective strategies for fall-related head injury prevention.

  • 25.
    Iglesias, Martín
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Araque, Oscar
    Intelligent Systems Group, ETSI Telecomunicación, Universidad Politécnica de Madrid, Avda. Complutense 30, Madrid, 28040, Spain..
    Iglesias, Carlos
    Intelligent Systems Group, ETSI Telecomunicación, Universidad Politécnica de Madrid, Avda. Complutense 30, Madrid, 28040, Spain..
    A Toxic Style Transfer Method Based on the Delete–Retrieve–Generate Framework Exploiting Toxic Lexicon Semantic Similarity2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 15, article id 8590Article in journal (Refereed)
    Abstract [en]

    Whether consciously or inadvertently, our messages can include toxic language which contributes to the polarization of social networks. Intelligent techniques can help us detect these expressions and even change them into kinder expressions by applying style transfer techniques. This work aims to advance detoxification style transfer techniques using deep learning and semantic similarity technologies. The article explores the advantages of a toxicity-deletion method that uses linguistic resources in a detoxification system. For this purpose, we propose a method that removes toxic words from the source sentence using a similarity function with a toxic vocabulary. We present two models that leverage it, namely, LexiconGST and MultiLexiconGST, which are based on the Delete –Retrieve–Generate framework. Experimental results show that our models perform well in the detoxification task compared to other state-of-the-art methods. Finally, this research confirms that linguistic resources can guide deep learning techniques and improve their performance.

  • 26.
    Iqbal, Javed
    et al.
    Univ Sains Malaysia, Sch Elect & Elect Engn, Engn Campus, Nibong Tebal 14300, Penang, Malaysia.;Gomal Univ, Elect Engn Dept, Dera Ismail Khan 29050, Pakistan..
    Illahi, Usman
    Gomal Univ, Elect Engn Dept, Dera Ismail Khan 29050, Pakistan..
    Khan, Muhammad Abbas
    Baluchistan Univ Informat Technol Engn & Manageme, Dept Elect Engn, Quetta 87300, Pakistan..
    Rauf, Abdul
    Natl Univ Sci & Technol, Dept Elect Engn, H-12, Islamabad 44000, Pakistan..
    Ali, Esraa Mousa
    Amman Arab Univ, Fac Aviat Sci, Amman 11953, Jordan..
    Bari, Inam
    Mil Technol Coll, Syst Engn Dept, Muscat 111, Oman..
    Ali, Haider
    Univ Technol, Dept Elect & Elect Engn Technol, Nowshera 24100, Pakistan..
    Khan, Muhammad Amir
    COMSATS Univ, Dept Comp Sci, Abbottabad Campus, Abbottabad 22020, Pakistan..
    Alibakhshikenari, Mohammad
    Univ Carlos III Madrid, Dept Signal Theory & Commun, Madrid 28911, Spain..
    Dalarsson, Mariana
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    A Novel Single-Fed Dual-Band Dual-Circularly Polarized Dielectric Resonator Antenna for 5G Sub-6GHz Applications2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 10, article id 5222Article in journal (Refereed)
    Abstract [en]

    In this research article, a single-fed dual-band circular polarized (CP) dielectric resonator antenna (DRA) for dual-function communication, such as GPS and WLAN, was made. Initially, the proposed design process was initiated by designing a linearly polarized singly fed-DRA. To attain CP fields, the cross-shape conformal metal strip was optimized to excite the fundamental and the high-order mode in the two frequency bands. The metallic strip (parasitic) was utilized on top of the rectangular DRA to improve and widen the impedance and axial ratio (AR) bandwidth. This step led to a 2.73% improvement on the lower band and an impact of 6.5% on the upper band while on the other side a significant improvement was witnessed in the AR bandwidth in both frequency bands. A prototype was designed and fabricated in order to validate its operations. The measurement outcomes of the proposed antennas authenticated wideband impedance bandwidths of 6.4% and 25.26%, and 3-dB axial ratios (AR) of 21.26% and 27.82% respectively. The prototype is a decent candidate for a global positioning system (GPS) and wireless local area network (WLAN).

  • 27. Irshad, Muneeb
    et al.
    Siraj, Khurram
    Raza, Rizwan
    Ali, Anwar
    Tiwari, Pankaj
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Rafique, Asia
    Ali, Amjad
    Ullah, Muhammad Kaleem
    Usman, Arslan
    A Brief Description of High Temperature Solid Oxide Fuel Cell's Operation, Materials, Design, Fabrication Technologies and Performance2016In: Applied Sciences, E-ISSN 2076-3417, Vol. 6, no 3Article, review/survey (Refereed)
    Abstract [en]

    Today's world needs highly efficient systems that can fulfill the growing demand for energy. One of the promising solutions is the fuel cell. Solid oxide fuel cell (SOFC) is considered by many developed countries as an alternative solution of energy in near future. A lot of efforts have been made during last decade to make it commercial by reducing its cost and increasing its durability. Different materials, designs and fabrication technologies have been developed and tested to make it more cost effective and stable. This article is focused on the advancements made in the field of high temperature SOFC. High temperature SOFC does not need any precious catalyst for its operation, unlike in other types of fuel cell. Different conventional and innovative materials have been discussed along with properties and effects on the performance of SOFC's components (electrolyte anode, cathode, interconnect and sealing materials). Advancements made in the field of cell and stack design are also explored along with hurdles coming in their fabrication and performance. This article also gives an overview of methods required for the fabrication of different components of SOFC. The flexibility of SOFC in terms fuel has also been discussed. Performance of the SOFC with varying combination of electrolyte, anode, cathode and fuel is also described in this article.

  • 28. Kabliman, Evgeniya
    et al.
    Ruban, Andrei V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Blaha, Peter
    Peil, Oleg
    Schwarz, Karlheinz
    Ab Initio Study of Lattice Site Occupancies in Binary Sigma Phases Using a Single-Site Mean Field Model2012In: Applied Sciences, E-ISSN 2076-3417, Vol. 2, no 3, p. 654-668Article in journal (Refereed)
    Abstract [en]

    The site occupation of binary Fe-Cr, Co-Cr, Re-W and Fe-V sigma phases is studied in the present work with a first-principles-based single-site mean field theory. We show that the alloy components in these systems exhibit similar site preferences except for the Re-W system, where the occupation of two sites is reversed in agreement with previously published works. In case of the FeV sigma phase, for which the size mismatch between the alloy components is large, we also include into our consideration the effect of local lattice relaxations. The obtained results are found in good agreement with the experimental data and previous theoretical studies.

  • 29.
    Khan, Muhammad Abbas
    et al.
    Balochistan Univ Informat Technol Engn & Manageme, Dept Elect Engn, Quetta 87300, Pakistan..
    Al Harbi, Abdullah G.
    Jouf Univ, Dept Elect Engn, Fac Engn, Sakaka 42421, Saudi Arabia..
    Kiani, Saad Hassan
    IIC Univ Technol, Dept Elect Engn, Phnom Penh 121206, Cambodia.;Prince Sultan Univ, Coll Engn, Smart Syst Engn Lab, Riyadh 11586, Saudi Arabia..
    Nordin, Anis Nurashikin
    Int Islamic Univ Malaysia, Dept Elect & Comp Engn, Kuala Lumpur 43200, Malaysia..
    Munir, Mehr E.
    Iqra Natl Univ, Dept Elect Engn, Peshawar 25000, Pakistan..
    Saeed, Sohail Imran
    Iqra Natl Univ, Dept Elect Engn, Peshawar 25000, Pakistan..
    Iqbal, Javed
    Gomal Univ, Fac Engn & Technol, Dept Elect Engn, Dera Ismail Khan 29050, Pakistan.;Univ Sains Malaysia, Sch Elect & Elect Engn, Engn Campus, Nibog Tebal 14300, Malaysia..
    Ali, Esraa Mousa
    Amman Arab Univ, Fac Aviat Sci, Amman 11953, Jordan..
    Alibakhshikenari, Mohammad
    Univ Carlos III Madrid, Dept Signal Theory & Communicat, Madrid 28911, Spain..
    Dalarsson, Mariana
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    mmWave Four-Element MIMO Antenna for Future 5G Systems2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 9, p. 4280-, article id 4280Article in journal (Refereed)
    Abstract [en]

    This paper presents an S-shape four-port Multiple Input Multiple Output (MIMO) wideband mmWave antenna with bandwidth of 25 GHz to 39 GHz. The antenna is designed on 0.254 mm ultra-thin RO5880 with permittivity of 2.3. The dimensions of proposed S-shape antenna are 10 x 12 mm for single element and 24 x 24 mm for four-port MIMO configuration. A decoupling network is introduced to further compress mutual coupling among MIMO elements. The peak gain achieved is 7.1 dBi and MIMO assembly delivers diversity scheme. The proposed MIMO antenna is fabricated, and simulated results are found to be in excellent agreement with simulations. Through the results obtained, the proposed MIMO antenna system can be considered as a potential candidate for future mmWave devices.

  • 30.
    Kholoma, Ezekiel
    et al.
    Botswana Int Univ Sci & Technol, Dept Civil & Environm Engn, Private Bag 16, Palapye, Botswana..
    Renman, Agnieszka
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Filter Media-Packed Bed Reactor Fortification with Biochar to Enhance Wastewater Quality2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 3, article id 790Article in journal (Refereed)
    Abstract [en]

    Contamination of water sources by inappropriately disposed poorly treated wastewater from countryside establishments is a worldwide challenge. This study tested the effectiveness of retrofitting sand (Sa)- and gas-concrete (GC)-packed reactors with biochar

  • 31.
    Li, Shicheng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Yang, James
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. Vattenfall AB, R&D Hydraul Lab, S-81426 Alvkarleby, Sweden..
    Effects of Inclination Angles on Stepped Chute Flows2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 18, article id 6202Article in journal (Refereed)
    Abstract [en]

    Owing to its effective energy dissipation and aeration, a stepped spillway is commonly used for flood release in hydraulic projects. Its conventional design features horizontal step surfaces. Designed for certain flow rates, it does not function satisfactorily at larger discharges. To improve this, layouts with inclined step surfaces, both downward and upward, are proposed. Computational fluid dynamics (CFD) modelling in 3D is performed to examine and compare their flow properties in the skimming flow. The results suggest that a shift from a downward to an upward layout leads to a gradual decrease in the flow velocity at the chute end; the latter exhibit higher energy dissipation efficiency. Moreover, equations are developed to estimate the velocity and energy loss. The flow velocity in the developing zone, described by a power law, shows a decline with an increase in the angle of inclination. The downward layout is subjected to somewhat higher risk of cavitation if implemented in a prototype. The extreme pressure loads acting upon an upward layout are larger, and a correlation is proposed for its prediction. On an inclined surface, either upward or downward, the pressure demonstrates an S-shaped distribution. On a vertical surface, the flow pressure increases, after an initial decline over a short distance, towards the chute bottom.

  • 32. Liu, Yi
    et al.
    Chen, Yuting
    Jiang, Xiaowu
    Ni, Qianying
    Liu, Chen
    Shang, Fangfang
    Xia, Qingchao
    Zhang, Sheng
    Self-Assembly at a Macroscale Using Aerodynamics2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 15, p. 7676-7676Article in journal (Refereed)
    Abstract [en]

    Intuitive self-assembly devices are of great significance to the emerging applications of self-assembly theory. In this paper, a novel intuitive device with an aerodynamic system is fabricated for the self-assembly experiment. Table tennis balls were used as the objects to be assembled during the self-assembly process. To understand more about the system, two experiments were designed—the directed assembly experiment was conducted to organize a specific structure and to explore the influences of environmental variables, and the indirect assembly experiment repeated with the “bottom-up” self-organization process and expressed the characteristics of “the optimization” and “the emergence” in the self-organization process. This article expressed a novel self-assembly approach at a macroscale and created a new choice or idea for the structural design and the optimization method.

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  • 33.
    Ma, Xinwei
    et al.
    Hebei Univ Technol, Sch Civil & Transportat Engn, Tianjin 300401, Peoples R China..
    Yin, Yurui
    Hebei Univ Technol, Sch Civil & Transportat Engn, Tianjin 300401, Peoples R China..
    Jin, Yuchuan
    KTH, School of Architecture and the Built Environment (ABE).
    He, Mingjia
    Southeast Univ, Sch Transportat, Dongnandaxue Rd 2, Nanjing 211189, Peoples R China..
    Zhu, Minqing
    Hebei Univ Technol, Sch Architecture & Art Design, Tianjin 300401, Peoples R China..
    Short-Term Prediction of Bike-Sharing Demand Using Multi-Source Data: A Spatial-Temporal Graph Attentional LSTM Approach2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 3, article id 1161Article in journal (Refereed)
    Abstract [en]

    As a convenient, economical, and eco-friendly travel mode, bike-sharing greatly improved urban mobility. However, it is often very difficult to achieve a balanced utilization of shared bikes due to the asymmetric spatio-temporal user demand distribution and the insufficient numbers of shared bikes, docks, or parking areas. If we can predict the short-run bike-sharing demand, it will help operating agencies rebalance bike-sharing systems in a timely and efficient way. Compared to the statistical methods, deep learning methods can automatically learn the relationship between the inputs and outputs, requiring less assumptions and achieving higher accuracy. This study proposes a Spatial-Temporal Graph Attentional Long Short-Term Memory (STGA-LSTM) neural network framework to predict short-run bike-sharing demand at a station level using multi-source data sets. These data sets include historical bike-sharing trip data, historical weather data, users' personal information, and land-use data. The proposed model can extract spatio-temporal information of bike-sharing systems and predict the short-term bike-sharing rental and return demand. We use a Graph Convolutional Network (GCN) to mine spatial information and adopt a Long Short-Term Memory (LSTM) network to mine temporal information. The attention mechanism is focused on both temporal and spatial dimensions to enhance the ability of learning temporal information in LSTM and spatial information in GCN. Results indicate that the proposed model is the most accurate compared with several baseline models, the attention mechanism can help improve the model performance, and models that include exogenous variables perform better than the models that only consider historical trip data. The proposed short-term prediction model can be used to help bike-sharing users better choose routes and to help operators implement dynamic redistribution strategies.

  • 34.
    Maffei, Antonio
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production engineering.
    Mura, Michela Dalle
    Univ Pisa, Dept Civil & Ind Engn, I-56122 Pisa, Largo Lazzarino, Italy..
    Monetti, Fabio Marco
    KTH, School of Industrial Engineering and Management (ITM), Production engineering.
    Boffa, Eleonora
    KTH, School of Industrial Engineering and Management (ITM), Production engineering.
    Dynamic Mixed Reality Assembly Guidance Using Optical Recognition Methods2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 3, article id 1760Article in journal (Refereed)
    Abstract [en]

    Augmented (AR) and Mixed Reality (MR) technologies are enablers of the Industry 4.0 paradigm and are spreading at high speed in production. Main applications include design, training, and assembly guidance. The latter is a pressing concern, because assembly is the process that accounts for the biggest portion of total cost within production. Teaching and guiding operators to assemble with minimal effort and error rates is pivotal. This work presents the development of a comprehensive MR application for guiding novice operators in following simple assembly instructions. The app follows innovative programming logic and component tracking in a dynamic environment, providing an immersive experience that includes different guidance aids. The application was tested by experienced and novice users, data were drawn from the performed experiments, and a questionnaire was submitted to collect the users' perception. Results indicate that the MR application was easy to follow and even gave confidence to inexperienced subjects. The guidance support was perceived as useful by the users, though at times invasive in the field of view. Further development effort is required to draw from this work a complete and usable architecture for MR application in assembly, but this research forms the basis to achieve better, more consistent instructions for assembly guidance based on component tracking.

  • 35.
    Meng, Boyang
    et al.
    Harbin Univ Sci & Technol, Key Lab Adv Mfg & Intelligent Technol, Minist Educ, Harbin 150080, Peoples R China..
    Liu, Xianli
    Harbin Univ Sci & Technol, Key Lab Adv Mfg & Intelligent Technol, Minist Educ, Harbin 150080, Peoples R China..
    Li, Maoyue
    Harbin Univ Sci & Technol, Key Lab Adv Mfg & Intelligent Technol, Minist Educ, Harbin 150080, Peoples R China..
    Liang, Steven Y.
    Georgia Inst Technol, George W Woodruff Sch Mech Engn, Atlanta, GA 30332 USA..
    Wang, Lihui
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Sustainable Production Systems.
    Wang, Zhixue
    Harbin Univ Sci & Technol, Key Lab Adv Mfg & Intelligent Technol, Minist Educ, Harbin 150080, Peoples R China..
    Uniformity, Periodicity and Symmetry Characteristics of Forces Fluctuation in Helical-Edge Milling Cutter2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 6, article id 2693Article in journal (Refereed)
    Abstract [en]

    Under most processing conditions, the milling force is expected to be stable and not to fluctuate, in order to improve the processing quality. This study focuses on analyzing the force fluctuation characteristics under conditions of different processing and cutter parameters. An original model is proposed to predict the force fluctuation during the milling process of a helical-edge cutter. At the same time, three force fluctuation characteristics related to the axial cutting depth and cutter parameters are determined: uniformity, periodicity and symmetry. The corresponding mathematical derivation and proof method are given for the first time through a force transformation of projecting the superposition chip thickness on a virtual cutting edge. On this basis, a fast estimation method and an accurate simulation method for force fluctuation prediction are established to quantify the intensity of force fluctuations under different parameters. Both two prediction methods and the experimental cutting tests validate the proposed theory effectively. The result shows a high potential of the proposed theory for studying the force behavior under different milling parameters or cutter parameters and at least 75% of the test workload can be reduced.

  • 36.
    Montes, Maria Jose
    et al.
    Univ Nacl Educ Distancia UNED, ETS Ingn Ind, C-Juan Rosal 12, Madrid 28040, Spain..
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    D'Souza, David
    Univ Nacl Educ Distancia UNED, ETS Ingn Ind, C-Juan Rosal 12, Madrid 28040, Spain..
    Linares, Jose Ignacio
    Comillas Pontif Univ, Rafael Marino Chair New Energy Technol, Alberto Aguilera 25, Madrid 28015, Spain..
    Thermoeconomic Analysis of Concentrated Solar Power Plants Based on Supercritical Power Cycles2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 13, article id 7836Article in journal (Refereed)
    Abstract [en]

    Featured Application This work is intended as a guide for the design of solar thermal tower plants based on a microchannel radial receiver refrigerated by a pressurised gas, and coupled to a supercritical CO2 power cycle. The work demonstrates the influence of the receiver configuration on the plant performance and investment costs. Solar thermal power plants are an alternative for the future energy context, allowing for a progressive decarbonisation of electricity production. One way to improve the performance of such plants is the use of supercritical CO2 power cycles. This article focuses on a solar thermal plant with a central solar receiver coupled to a partial cooling cycle, and it conducts a comparative study from both a thermal and economic perspective with the aim of optimising the configuration of the receiver. The design of the solar receiver is based on a radial configuration, with absorber panels converging on the tower axis; the absorber panels are compact structures through which a pressurised gas circulates. The different configurations analysed keep a constant thermal power provided by the receiver while varying the number of panels and their dimensions. The results demonstrate the existence of an optimal configuration that maximises the exergy efficiency of the solar subsystem, taking into account both the receiver exergy efficiency and the heliostat field optical efficiency. The evolution of electricity generation cost follows a similar trend to that of the exergy efficiency, exhibiting minimum values when this efficiency is at its maximum.

  • 37.
    Moosavi, Seyed Mohammad Hossein
    et al.
    Univ Malaya, Fac Engn, Dept Civil Engn, Kuala Lumpur 50603, Malaysia..
    Ma, Zhenliang
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Armaghani, Danial Jahed
    South Ural State Univ, Inst Architecture & Construct, Dept Urban Planning Engn Networks & Syst, 76 Lenin Prospect, Chelyabinsk 454080, Russia..
    Aghaabbasi, Mahdi
    Chulalongkorn Univ, Transportat Inst, Bangkok 10330, Thailand..
    Ganggayah, Mogana Darshini
    Monash Univ, Malaysia Sch Business, Subang Jaya 47500, Selangor, Malaysia..
    Wah, Yuen Choon
    Univ Malaya, Fac Engn, Dept Civil Engn, Kuala Lumpur 50603, Malaysia..
    Ulrikh, Dmitrii Vladimirovich
    South Ural State Univ, Inst Architecture & Construct, Dept Urban Planning Engn Networks & Syst, 76 Lenin Prospect, Chelyabinsk 454080, Russia..
    Understanding and Predicting the Usage of Shared Electric Scooter Services on University Campuses2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 18, article id 9392Article in journal (Refereed)
    Abstract [en]

    Electric vehicles (EVs) have been progressing rapidly in urban transport systems given their potential in reducing emissions and energy consumptions. The Shared Free-Floating Electric Scooter (SFFES) is an emerging EV publicized to address the first-/last-mile problem in travel. It also offers alternatives for short-distance journeys using cars or ride-hailing services. However, very few SFFES studies have been carried out in developing countries and for university populations. Currently, many universities are facing an increased number of short-distance private car travels on campus. The study is designed to explore the attitudes and perceptions of students and staff towards SFFES usage on campus and the corresponding influencing factors. Three machine learning models were used to predict SFFES usage. Eleven important factors for using SFFESs on campus were identified via the supervised and unsupervised feature selection techniques, with the top three factors being daily travel mode, road features (e.g., green spaces) and age. The random forest model showed the highest accuracy in predicting the usage frequency of SFFESs (93.5%) using the selected 11 variables. A simulation-based optimization analysis was further conducted to discover the characterization of SFFES users, barriers/benefits of using SFFESs and safety concerns.

  • 38.
    Nyyssönen, Tuomo
    et al.
    Swerim AB, Stockholm, Sweden.
    Malmström, Mikael
    Swerim AB, Stockholm, Sweden.
    David, Lindell
    Swerim AB, Stockholm, Sweden.
    Jansson, Anton
    Swerim AB, Stockholm, Sweden.
    Lönnqvist, Johan
    Swerim AB, Stockholm, Sweden.
    Bäcke, Linda
    SSAB, Borlänge, Sweden.
    Hutchinson, Bevis
    Swerim AB, Stockholm, Sweden.
    Significance of Annealing Twins in Laser Ultrasonic Measurements of Grain Size in High-Strength Low-Alloy Steels2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 6Article in journal (Refereed)
    Abstract [en]

    In this study, we demonstrate the significance of austenite annealing twin boundaries when calibrating laser ultrasonic measurements for gauging austenite grain size in situ during the thermomechanical processing of high-strength low-alloy steels. Simple calculations show how differences in twinning density can lead to errors in grain size measurements if twins are disregarded during calibration and the method is used for a broad range of steels. Conversely, when calibration is performed using alloys with a metastable austenite microstructure at room temperature, the same calibration is suitable for a broad range of HSLA steels, provided that annealing twins are taken into account. Since light optical microscopy does not allow the characterization of annealing twins in low-alloy steel, the verification of the laser ultrasonic results was conducted using the novel approach of comparing the twinned grain sizes obtained using the ultrasonic method in low-alloy steels with the austenite grain maps reconstructed from martensite orientation maps measured using electron backscatter diffraction. Finally, we show how differences in twinning density occur even for alloys with a roughly similar stacking fault energy, further highlighting the importance of annealing twins in the calibration of laser ultrasonic measurements for industrial use.

  • 39.
    Oortwijn, Wytse
    et al.
    Swiss Fed Inst Technol, Dept Comp Sci, CH-8092 Zurich, Switzerland..
    Gurov, Dilian
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Huisman, Marieke
    Univ Twente, Formal Methods & Tools, NL-7500 AE Enschede, Netherlands..
    An Abstraction Technique for Verifying Shared-Memory Concurrency2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 11, article id 3928Article in journal (Refereed)
    Abstract [en]

    Modern concurrent and distributed software is highly complex. Techniques to reason about the correct behaviour of such software are essential to ensure its reliability. To be able to reason about realistic programs, these techniques must be modular and compositional as well as practical by being supported by automated tools. However, many existing approaches for concurrency verification are theoretical and focus primarily on expressivity and generality. This paper contributes a technique for verifying behavioural properties of concurrent and distributed programs that balances expressivity and usability. The key idea of the approach is that program behaviour is abstractly modelled using process algebra, and analysed separately. The main difficulty is presented by the typical abstraction gap between program implementations and their models. Our approach bridges this gap by providing a deductive technique for formally linking programs with their process-algebraic models. Our verification technique is modular and compositional, is proven sound with Coq, and has been implemented in the automated concurrency verifier VerCors. Moreover, our technique is demonstrated on multiple case studies, including the verification of a leader election protocol.

  • 40.
    Ozolins, Oskars
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, Networks Unit, S-16440 Kista, Sweden.;Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Udalcovs, Aleksejs
    RISE Res Inst Sweden, Networks Unit, S-16440 Kista, Sweden..
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Spolitis, Sandis
    Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia.;Riga Tech Univ, Commun Technol Res Ctr, LV-1048 Riga, Latvia..
    Bobrovs, Vjaceslavs
    Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Jacobsen, Gunnar
    RISE Res Inst Sweden, Networks Unit, S-16440 Kista, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    100 Gbaud On-Off Keying/Pulse Amplitude Modulation Links in C-Band for Short-Reach Optical Interconnects2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 9, article id 4284Article in journal (Refereed)
    Abstract [en]

    We experimentally evaluate the high-speed on-off keying (OOK) and four-level pulse amplitude modulation (PAM4) transmitter's performance in C-band for short-reach optical interconnects. We demonstrate up to 100 Gbaud OOK and PAM4 transmission over a 400 m standard single-mode fiber with a monolithically integrated externally modulated laser (EML) having 100 GHz 3 dB bandwidth with 2 dB ripple. We evaluate its capabilities to enable 800 GbE client-side links based on eight, and even four, optical lanes for optical interconnect applications. We study the equalizer's complexity when increasing the baud rate of PAM4 signals. Furthermore, we extend our work with numerical simulations showing the required received optical power (ROP) for a certain bit error rate (BER) for the different combinations of the effective number of bits (ENOB) and extinction ratio (ER) at the transmitter. We also show a possibility to achieve around 1 km dispersion uncompensated transmission with a simple decision feedback equalizer (DFE) for a 100 Gbaud OOK, PAM4, and eight-level PAM (PAM8) link having the received power penalty of around 1 dB.

  • 41. Palma, Giorgio
    et al.
    Mao, Huina
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Burghignoli, Lorenzo
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Iemma, Umberto
    Acoustic Metamaterials in Aeronautics2018In: Applied Sciences, E-ISSN 2076-3417, Vol. 8, no 6, article id 971Article in journal (Refereed)
    Abstract [en]

    Metamaterials, man-made composites that are scaled smaller than the wavelength, have demonstrated a huge potential for application in acoustics, allowing the production of sub-wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, and acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities for the control of acoustic patterns and sound at sub-wavelength scales. Despite the tremendous growth in research on acoustic metamaterials during the last decade, the potential of metamaterial-based technologies in aeronautics has still not been fully explored, and its utilization is still in its infancy. Thus, the principal concepts mentioned above could very well provide a means to develop devices that allow the mitigation of the impact of civil aviation noise on the community. This paper gives a review of the most relevant works on acoustic metamaterials, analyzing them for their potential applicability in aeronautics, and, in this process, identifying possible implementation areas and interesting metabehaviors. It also identifies some technical challenges and possible future directions for research with the goal of unveiling the potential of metamaterials technology in aeronautics.

  • 42.
    Pan, Shiwei
    et al.
    Univ Sci & Technol Beijing, State Key Lab Adv Met & Mat, Beijing 100083, Peoples R China..
    Zhou, Xianglin
    Univ Sci & Technol Beijing, State Key Lab Adv Met & Mat, Beijing 100083, Peoples R China..
    Chen, Kaixuan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Univ Sci & Technol Beijing, Inst Adv Mat & Technol, Beijing 100083, Peoples R China.
    Yang, Ming
    Univ Sci & Technol Beijing, Sch Mat Sci & Engn, Beijing 100083, Peoples R China..
    Cao, Yudong
    Univ Sci & Technol Beijing, Inst Adv Mat & Technol, Beijing 100083, Peoples R China..
    Chen, Xiaohua
    Univ Sci & Technol Beijing, State Key Lab Adv Met & Mat, Beijing 100083, Peoples R China..
    Wang, Zidong
    Univ Sci & Technol Beijing, Sch Mat Sci & Engn, Beijing 100083, Peoples R China..
    In-Situ Nanoparticles: A New Strengthening Method for Metallic Structural Material2018In: Applied Sciences, E-ISSN 2076-3417, Vol. 8, no 12, article id 2479Article, review/survey (Refereed)
    Abstract [en]

    Over the past several years, coherent interface strengthening was proposed and has since drawn much attention. Unfortunately, many fabrication techniques are restricted to very small size. Recently, a brand new method of in-situ nanoparticle strengthening was systematically investigated, which was proved to be an efficacious way to optimize microstructure and improve mechanical property by utilizing uniformly dispersed nanoparticles. In this review, we summarized recent related advances in investigated steels and Cu alloys, including details of preparation technique and characterization of in-situ nanoparticles. In-situ nanoparticles formed in the melt possess a coherent/semi-coherent relationship with the matrix, which has a similar effect of coherent interface strengthening. In this case, bulk metallic structural materials with dispersed nanoparticles in the matrix can be fabricated through conventional casting process. The effects of in-situ nanoparticles on grain refinement, inhibiting segregation, optimizing inclusions and strengthening are also deeply discussed, which is beneficial for obtaining comprehensive mechanical response. Consequently, it is expected that in-situ nanoparticle strengthening method will become a potential future direction in industrial mass production.

  • 43.
    Panajotov, Krassimir
    et al.
    Vrije Univ Brussels, Dept Appl Phys & Photon IR TONA, Pl Laan 2, B-1050 Brussels, Belgium.;Bulgarian Acad Sci, Inst Solid State Phys, 72 Tzarigradsko Chaussee Blvd, Sofia 1784, Bulgaria..
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Coupled-Cavity VCSEL with an Integrated Electro-Absorption Modulator: Small- and Large-Signal Modulation Analysis2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 17, article id 6128Article in journal (Refereed)
    Abstract [en]

    Featured Application VCSELs are widely employed in Fiber to the Home links, computer networks and optical interconnects because of their low power consumption, small footprint, high reliability, easy packaging, single longitudinal mode emission, high modulation speed, low cost and circular output beam. Short- and medium-range optical communication links demand for continuous increase of VCSEL modulation speed. VCSEL direct modulation speed is however limited by the relaxation oscillation frequency and new approaches as, e.g., integrating VCSEL with an electro-absorption modulator (EAM) are required. Hereby, we demonstrate that an integrated EAM-VCSEL is capable of producing a resonantly enhanced, flat modulation response with ultrahigh bandwidth of 100Gbs for applications in optical communication links. We consider an integrated electro-absorption modulator within a coupled-cavity VCSEL structure (EAM-VCSEL). We derive expressions for the modulation transfer function (MTF) of the EAM-VCSEL for small-signal modulation of either VCSEL injection current or EAM losses. For current modulation, the cut-off frequency remains limited by relaxation oscillation frequency. For EAM loss modulation, the MTF curve is much flatter and its shape around the relaxation oscillation frequency displays either a well-pronounced maximum, both a maximum and a minimum or a sharp minimum only depending on the bias point of the EAM losses. Such features have been found experimentally in Marigo-Lombart et al., J. Physiscs: Photonics, 1, 2019, but remained unexplained hitherto. Furthermore, the cut-off frequency remains beyond 100 GHz for moderate and week coupling between the VCSEL and EAM cavities. Such ultrahigh bandwidth modulation is due to the fact that the changes of EAM impact much less the optical power distribution along the EAM-VCSEL and, consequently, the confinement factor and photon density in the VCSEL cavity. The three cases of strong, intermediate and weak coupling are also considered when carrying out the large-signal modulation response of the EAM-VCSEL and a clear open-eye diagram is demonstrated at 100 Gbs for an optimal EAM cavity length.

  • 44.
    Papaioannou, Georgios
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Jerrelind, Jenny
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Multi-Objective Optimisation of Tyre and Suspension Parameters during Cornering for Different Road Roughness Profiles2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 13, p. 5934-5934Article in journal (Refereed)
    Abstract [en]

    Effective emission control technologies and novel propulsion systems have been developed for road vehicles, decreasing exhaust particle emissions. However, work has to be done on non-exhaust traffic related sources such as tyre–road interaction and tyre wear. Given that both are inevitable in road vehicles, efforts for assessing and minimising tyre wear should be considered. The amount of tyre wear is because of internal (tyre structure, manufacturing, etc.) and external (suspension configuration, speed, road surface, etc.) factors. In this work, the emphasis is on the optimisation of such parameters for minimising tyre wear, but also enhancing occupant’s comfort and improving vehicle handling. In addition to the search for the optimum parameters, the optimisation is also used as a tool to identify and highlight potential trade-offs between the objectives and the various design parameters. Hence, initially, the tyre design (based on some chosen tyre parameters) is optimised with regards to the above-mentioned objectives, for a vehicle while cornering over both Class A and B road roughness profiles. Afterwards, an optimal solution is sought between the Pareto alternatives provided by the two road cases, in order for the tyre wear levels to be less affected under different road profiles. Therefore, it is required that the tyre parameters are as close possible and that they provide similar tyre wear in both road cases. Then, the identified tyre design is adopted and the optimum suspension design is sought for the two road cases for both passive and semi-active suspension types. From the results, significant conclusions regarding how tyre wear behaves with regards to passenger comfort and vehicle handling are extracted, while the results illustrate where the optimum suspension and tyre parameters have converged trying to compromise among the above objectives under different road types and how suspension types, passive and semi-active, could compromise among all of them more optimally. 

  • 45.
    Papakostas, Nikolaos
    et al.
    Laboratory for Advanced Manufacturing Simulation and Robotics (LAMS), School of Mechanical and Materials Engineering, University College Dublin, Dublin, D04 V1W8, Ireland.
    Wang, Lihui
    KTH, School of Industrial Engineering and Management (ITM), Production engineering.
    Makris, Sotiris
    Laboratory for Manufacturing Systems and Automation (LMS), Department of Mechanical Engineering and Aeronautics, University of Patras, Rio Patras, 26504, Greece.
    Mourtzis, Dimitris
    Laboratory for Manufacturing Systems and Automation (LMS), Department of Mechanical Engineering and Aeronautics, University of Patras, Rio Patras, 26504, Greece.
    Editorial of the Special Issue “Advanced Robotics Applications in Industry”2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 10, article id 5836Article in journal (Other academic)
  • 46.
    Patton, Declan A.
    et al.
    Federat Univ Australia, Australian Collaborat Res Injury Sport & Its Preve, Ballarat, Vic 3350, Australia.;Norwegian Sch Sport Sci, Oslo Sports Trauma Res Ctr OSTRC, N-0863 Oslo, Norway.;Univ Calgary, Fac Kinesiol, Sport Injury Prevent Res Ctr SIPRC, Calgary, AB T2N 1N4, Canada.;Childrens Hosp Philadelphia, Ctr Injury Res & Prevent, Philadelphia, PA 19104 USA..
    Mohammadi, Reza
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    McIntosh, Andrew S.
    Federat Univ Australia, Australian Collaborat Res Injury Sport & Its Preve, Ballarat, Vic 3350, Australia.;McIntosh Consultancy & Res, Sydney, NSW 2090, Australia..
    Radial and Oblique Impact Testing of Alpine Helmets onto Snow Surfaces2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 6, p. 3455-, article id 3455Article in journal (Refereed)
    Abstract [en]

    Recent studies have found that alpine helmets reduce the risk of focal injuries associated with radial impacts, which is likely due to current alpine helmet standards requiring helmets to be drop-tested on flat anvils with only linear acceleration pass criteria. There is a need to evaluate the performance of alpine helmets in more realistic impacts. The current study developed a method to assess the performance of alpine helmets for radial and oblique impacts on snow surfaces in a laboratory setting. Snow samples were collected from a groomed area of a ski slope. Radial impacts were performed as drop tests onto a stationary snow sample. Oblique impacts were performed as drop tests onto a snow sample moving horizontally. For radial impacts, snow sample collection time was found to significantly (p = 0.005) influence mean peak linear headform acceleration with an increase in ambient temperature softening the snow samples. For oblique tests, the recreational alpine sports helmet with a rotation-damping system (RDS) significantly (p = 0.002) reduced mean peak angular acceleration compared to the same helmets with no RDS by approximately 44%. The ski racing helmet also significantly (p = 0.006) reduced mean peak angular acceleration compared to the recreational alpine sports helmet with no RDS by approximately 33%, which was attributed to the smooth outer shell of the ski racing helmet. The current study helps to bridge the knowledge gap between real helmet impacts on alpine snow slopes and laboratory helmet impacts on rigid surfaces.

  • 47.
    Peterson, Viktor
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    On the Residual Static and Impact Capacity of Shear-Reinforced Concrete Beams Subjected to an Initial Impact2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 22, p. 11377-, article id 11377Article in journal (Refereed)
    Abstract [en]

    Impact loads in previous research showed to induce brittle responses of statically flexure-critical reinforced concrete (RC) beams designed for ductility. The impact load may produce flexural shear damage modes similar to that observed during quasi-static loads and local shear damage under the impact zone. The occurrence of shear damage modes during impact tests has been investigated extensively, but their effect on the residual quasi-static and dynamic capacity is not fully understood. For this aim, an initial high-velocity impact test initiated severe shear damage to RC beams. The beams were then tested quasi-statically and by sequential impact testing using the same setup as the initial tests. The results indicate a flexure-dominated response during sequential impact tests for beams containing extreme shear reinforcement amounts, favouring the energy-absorption capacity. Significant shear and flexural damage occurred for beams with less shear reinforcement, indicating a hybrid response that varied throughout the tests. The tests for the residual quasi-static capacity indicated severe consequences from initial local shear damage on the capacity, as shown by the brittle response of the beam with the most shear reinforcement. However, wide initial flexural cracks instead showed a favourable effect, as there was an indication of transfer from brittle to ductile failure. For beams showing both global and local shear damage, it was concluded that global shear damage modes were critical for the residual static and dynamic shear capacity.

  • 48.
    Petrovic, Jana
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Performance Evaluation of an Imaging Radiation Portal Monitor System2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 18, article id 9001Article in journal (Refereed)
    Abstract [en]

    An organic scintillator-based radiation portal monitor (RPM) prototype system with imaging capabilities has been developed based on the neutron-gamma emission tomography technique. The technique enables rapid detection and precise location of small amounts of special nuclear materials, such as plutonium, using time and energy correlations between fast neutrons and gamma rays from spontaneous fission with low false-alarm rates. These capabilities, in addition to state-of-the-art detection of various gamma-emitting sources, enables the novel imaging RPM concept to efficiently address global security threats from terrorism and the proliferation of nuclear weapons. The detector approach is simple and versatile and can easily be adapted for different applications in nuclear security, public safety, nuclear emergency response, and radiological surveying. In this work, basic performance parameters of the imaging RPM prototype system developed at KTH have been evaluated.

  • 49. Piana, E. A.
    et al.
    Petrogalli, C.
    Paderno, D.
    Carlsson, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Application of the wave propagation approach to sandwich structures: Vibro-acoustic properties of aluminum honeycomb materials2018In: Applied Sciences, E-ISSN 2076-3417, Vol. 8, no 1, article id 45Article in journal (Refereed)
    Abstract [en]

    Sandwich structures are manufactured using multiple combinations of materials for core and laminates. The real performances are influenced by variability in the composing layers and even by the uncertainties introduced while bonding them together. Therefore, experimental tests are usually the preferred way to assess the most important parameters required to develop and to characterize the product, the main downsides lying in their cost and time consumption. This work explores a practical application of the wave propagation approach by means of a case study, in which some significant properties of an aluminum honeycomb panel are obtained starting from simple vibro-acoustic tests carried out on beam specimens. After determining the frequency-dependent bending stiffness function, the sound transmission loss is predicted and compared with the experimental results obtained in sound transmission suites. The same vibro-acoustic tests are used to estimate the core shear modulus. Finally, a parametric study is proposed to show how this technique can be effectively used in the early design stage, when producing physical samples is often impossible due to time and money constraints. The method proved to be a reliable and powerful tool in all the tested applications, providing good results with limited computational effort.

  • 50.
    Ploskic, Adnan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology. Bravida Holding AB, Mikrofonvagen 28, S-12637 Hagersten, Sweden..
    Wang, Qian
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology. Uponor AB, Hackstavagen 1, S-72132 Vasteras, Sweden..
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology. Univ Calif Berkeley, Dept Architecture, Ctr Built Environm, Berkeley, CA 94720 USA..
    Mapping Relevant Parameters for Efficient Operation of Low-Temperature Heating Systems in Nordic Single-Family Dwellings2018In: Applied Sciences, E-ISSN 2076-3417, Vol. 8, no 10, article id 1973Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to map the parameters that have the greatest impact on the environmental impact of heating systems usually used in Nordic single-family dwellings. The study focused on mapping the technical requirements for efficient operation of heating systems in a broader context. The results suggest that the ability of a heating system to be operated with a low-temperature water supply depends to a large extent on the heating demand of a building. It was shown that an increase in the water flow rate in hydronic circuits would significantly increase the thermal efficiency from analyzed heating systems. This increase would not increase the pumping power need, nor would it create noise problems in distribution network if the distribution pipes and thermostatic valves were properly selected. However, this increase in water flow rate improved the efficiency of considered closed-loop heat pump. It was further shown that the efficiency of the heat pump could be additionally improved by halving the energy needs for the domestic hot-water and circulators. The main conclusion from this study is that exergy usage, CO2 emission and thereby environmental impact are significantly lower for heating systems that are operated with small temperature drops.

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