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  • 122901. Yang, L.
    et al.
    Yang, B.
    Sheng, Z.
    Wang, J. W.
    Dai, D. X.
    He, Sailing
    Compact 2x2 tapered multimode interference couplers based on SU-8 polymer rectangular waveguides2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, no 20Article in journal (Refereed)
    Abstract [en]

    A 2x2 tapered multimode interference (MMI) coupler is designed and fabricated by using air-cladded SU-8 rectangular waveguide, which is effective in reducing the device size and improving the self-imaging quality. The parabolically tapered MMI section is used to reduce further the size of the MMI coupler. A compact 2x2 coupler with a total MMI size of about 5.3x34.2 mu m(2) is demonstrated and characterized. The measurement results show that the fabricated 2x2 MMI coupler has relatively small excess loss and nonuniformity for both polarizations in a broad wavelength range (from 1480 to 1630 nm).

  • 122902. Yang, Lei
    et al.
    Cappel, Ute B.
    Unger, Eva L.
    Karlsson, Martin
    Karlsson, Karl Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Boschloo, Gerrit
    Hagfeldt, Anders
    Johansson, Erik M. J.
    Comparing spiro-OMeTAD and P3HT hole conductors in efficient solid state dye-sensitized solar cells2012In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 14, no 2, p. 779-789Article in journal (Refereed)
    Abstract [en]

    Two hole conductor materials, spiro-OMeTAD and P3HT, were compared in solid-state dye-sensitized solar cells. Two organic dyes containing one anchor unit (D35) or two anchor units (M3) were used in the comparison. Absorbed photon to current conversion efficiency close to unity was obtained for the devices with spiro-OMeTAD. Energy conversion efficiencies of 4.7% and 4.9% were measured for the devices with spiro-OMeTAD and the dyes D35 and M3, respectively. For the devices using the P3HT hole conductor the results were rather different comparing the two dye molecules, with energy conversion efficiencies of 3.2% and 0.5% for D35 and M3, respectively. Photo-induced absorption measurements suggest that the regeneration of the dyes, and the polymer infiltration, is not complete using P3HT, while spiro-OMeTAD regenerates the dyes efficiently. However, the TiO(2)/D35/P3HT system shows rather high energy conversion efficiency and electrochemical oxidation of the dyes on TiO(2) indicates that D35 have a more efficient dye to dye hole conduction than M3, which thereby might explain the higher performance. The dye hole conduction may therefore be of significant importance for optimizing the energy conversion in such hybrid TiO(2)/dye/polymer systems.

  • 122903. Yang, Lei
    et al.
    Xu, Bo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Bi, Dongqin
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Boschloo, Gerrit
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hagfeldt, Anders
    Johansson, Erik M. J.
    Initial Light Soaking Treatment Enables Hole Transport Material to Outperform Spiro-OMeTAD in Solid-State Dye-Sensitized Solar Cells2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 19, p. 7378-7385Article in journal (Refereed)
    Abstract [en]

    Efficient solid state dye-sensitized solar cells (sDSCs) were obtained using a small hole transport material, MeO-TPD (N,N,N',N'-tetrakis(4-methoxyphenyl)benzidine), after an initial light soaking treatment. It was discovered that the light soaking treatment for the MeO-TPD based solar cells is essential in order to achieve the high efficiency (4.9%), which outperforms spiro-OMeTAD based sDSCs using the same dye and device preparation parameters. A mechanism based on Li+ ion migration is suggested to explain the light soaking effect. It was observed that the electron lifetime for the MeO-TPD based sDSC strongly increases after the light soaking treatment, which explains the higher efficiency. After the initial light soaking treatment the device efficiency remains considerably stable with only 0.2% decrease after around 1 month (unsealed cells stored in dark).

  • 122904. Yang, Lei
    et al.
    Zhang, Jinbao
    Shen, Yang
    Park, Byung-Wook
    Bi, Dongqin
    Häggman, Leif
    Johansson, Erik M. J.
    Boschloo, Gerrit
    Hagfeldt, Anders
    Vlachopoulos, Nick
    Snedden, Alan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jarboui, Adel
    Chams, Amani
    Perruchot, Christian
    Jouini, Mohamed
    New Approach for Preparation of Efficient Solid-State Dye-Sensitized Solar Cells by Photoelectrochemical Polymerization in Aqueous Micellar Solution2013In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 4, no 23, p. 4026-4031Article in journal (Refereed)
    Abstract [en]

    Hereby, we present a new, cost-effective, and environmentally friendly method of preparing an efficient solid-state dye-sensitized solar cell (sDSC) using a PEDOT conducting polymer as the hole conductor and a recently developed organic sensitizer. PEDOT is generated and deposited on the dye-sensitized TiO2 electrode by in situ photoelectropolymerization of bis-EDOT in aqueous micellar solution. The advantages of this approach are the use of water as the solvent and the obtainment of a sDSC simply by adding a silver layer on the as-obtained polymer film deposited on dye/TiO2 without the need for electrolytic solution. The sDSC containing the film prepared as above is compared to those where the organic dye is used to generate the same polymer film but in organic solvent. The energy conversion efficiency values of the two cells appear comparable, 4.8% for sDSC prepared in the aqueous-phase polymerized PEDOT and 6% for the sDSC prepared with in organic-phase polymerized PEDOT.

  • 122905.
    Yang, Likang
    et al.
    Zhejiang Univ Sci & Technol, Coll Mech & Automot, Hangzhou 310023, Peoples R China.;Royal Inst Technol KTH, Dept Mech, SE-10044 Stockholm, Sweden..
    Duan, Fubin
    Zhejiang Univ Sci & Technol, Coll Mech & Automot, Hangzhou 310023, Peoples R China..
    Anders, E.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Key factors in optimal design of MR device except magnetic circuits2007In: NEW ADVANCES IN SIMULATION, MODELLING AND OPTIMIZATION (SMO '07) / [ed] Xu, D Gao, K Li, X Han, Z, WORLD SCIENTIFIC AND ENGINEERING ACAD AND SOC , 2007, p. 454-+Conference paper (Refereed)
    Abstract [en]

    Most of design processes of the MR device only focus on their magnetic circuit analysis. During the exploring of Magnetorheological(MR) fluid applications, the design method is getting important to MR devices in developing primary products. Based on the usual magnetic circuit design, the MR Adaptive structure design method was presented according to the whole requirement of Adaptive structure characteristics. In other words, the Adaptive structures design methods do not just execute optimization according to magnetic circuit requirement, and it can customize the whole system's key requirements. Besides usual magnetic circuit design analysis, by utilizing the structural parameters, the response time of MR devices was considered by analyzing the time constant of electromagnetic coils inside the MR devices too. Additionally, power consumption relevant to transient useful power was analyzed for structure design. Finally, based on the computation of magnetic field in finite element analysis method (COMSOL multiphsics), all these factors were illustrated respectively in a MR fluid valve based on the results of magnetic circuit design.

  • 122906. Yang, Likang
    et al.
    Duan, Fubin
    Eriksson, Anders
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Analysis of the optimal design strategy of a magnetorheological smart structure2008In: Smart materials and structures (Print), ISSN 0964-1726, E-ISSN 1361-665X, Vol. 17, no 1Article in journal (Refereed)
    Abstract [en]

    The exploration of magnetorheological (MR) fluid applications involves many fields. During the phase of theory analysis and experimental investigations, most of the research has been in developing primary products, and the design method is becoming important in MR device design. To establish general design guidelines, not with the usual MR smart structure design method which just complies with the presented yield stress of smart materials, in this paper, an MR smart structure design method is presented according to the whole requirement of smart structure characteristics. In other words, the smart structure design method does not just execute its optimization according to the presented MR fluid features, and it can customize or select the properties of MR fluid obeying the whole system requirements. Besides the usual magnetic circuit design analysis, the MR fluid physical content, such as the volume fraction of particles, was incorporated into the design parameters of the products. At the same time, by utilizing the structural parameters, the response time of MR devices was considered by analyzing the time constant of electromagnetic coils inside the MR devices too. Additionally, the power consumption relevant to transient useful power was analyzed for structure design. Finally, based on the computation of the magnetic field in a finite element (COMSOL multiphysics), all these factors were illustrated in an MR fluid valve based on the results of a magnetic circuit design.

  • 122907. Yang, Lin
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Qu, Yi
    Qu, Weisong
    Zhang, Xiao
    Hang, Yandi
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hua, Jianli
    Red turn-on fluorescent phenazine-cyanine chemodosimeters for cyanide anion in aqueous solution and its application for cell imaging2014In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 203, p. 833-847Article in journal (Refereed)
    Abstract [en]

    Two chemodosimeters PDMI and PMI for cyanide detection were designed and synthesized based onphenazinecyanine dyes with N-methyl indolium group as receptor unit. According to the specific reactivity of indolium C-N+ bond against cyanide anion, both of them featured high sensitivity with detectionlimit of 1.4 mu M and 200 nM, respectively, and high selectivity against other anions. The quenching effecton phenazine-cyanine fluorophore by strong intramolecular charge transfer (ICT) from phenazine donorto indolium receptor made both PDMI and PMI non-emissive at the original state. After addition ofcyanide, the ICT effect decreased and vanished leading to dramatic " off-on" fluorescence enhancement. PDMI which proceeded bilateral electrophilic reaction toward cyanide anion provided an emission signal at 580 nm in HEPES buffer with naked-eye detectable color change. Probe PMI utilized an unreactiveformyl group instead of one reactive N-methyl indolium group as the electron-withdrawing component. Due to the unilateral recognition process for cyanide the ICT orientation of PMI was redirectedthus exhibited fluorescence enhancement with maximum emission at 630 nm. Meanwhile, PMI wasapplied for monitoring intracellular cyanide in Hela cells and proved to achieve "off-on" fluorescentsignal confirmed by confocal laser scanning microscopic imaging.

  • 122908. Yang, Lin
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Yang, Jiabao
    Qu, Yi
    Hua, Jianli
    Colorimetric and Ratiometric Near-Infrared Fluorescent Cyanide Chemodosimeter Based on Phenazine Derivatives2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 4, p. 1317-1326Article in journal (Refereed)
    Abstract [en]

    Two new near-infrared chemodosimeters for cyanide anion based on 5,10-dihexyl-5,10-dihydrophenazine were designed and synthesized. With dicyano-vinyl groups as the recognition site and electron-withdrawing groups on both sides, probe 1 exhibited an intramolecular charge transfer (ICT) absorption band at 545 nm and emission band at 730 nm, respectively, and thus showed an ICT block process and realized an 'on-off" response after bilateral reaction with cyanide anions in CH3CN. Probe 2 utilized an unreactive formyl group instead of one of the two reactive dicyano-vinyl groups as the electron-withdrawing component. Due to the unilateral recognition process the ICT of probe 2 was redirected and lead to a remarkably colorimetric and ratiometric near-infrared (NIR) fluorescent response for cyanine. Both probes provided high sensitivity and selectivity with apparent response signals which can be observed by naked eyes, even in the copresence of various other interference anions. Optical spectroscopic techniques, NMR titration measurements, and density functional theory calculations were conducted to rationalize the sensing mechanisms of these two probes.

  • 122909. Yang, Liu
    et al.
    Kou, Pengfei
    He, Nan
    Dai, Hao
    He, Sailing
    KTH, School of Electrical Engineering (EES). KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Anomalous light trapping enhancement in a two-dimensional gold nanobowl array with an amorphous silicon coating2017In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, no 13, p. 14114-14124Article in journal (Refereed)
    Abstract [en]

    A facile polymethyl methacrylate-assisted turnover-transfer approach is developed to fabricate uniform hexagonal gold nanobowl arrays. The bare array shows inferior light trapping ability compared to its inverted counterpart (a gold nanospherical shell array). Surprisingly, after being coated with a 60-nm thick amorphous silicon film, an anomalous light trapping enhancement is observed with a significantly enhanced average absorption (82%), while for the inverted nanostructure, the light trapping becomes greatly weakened with an average absorption of only 66%. Systematic experimental and theoretical results show that the main reason for the opposite light trapping behaviors lies in the top amorphous silicon coating, which plays an important role in mediating the excitation of surface plasmon polaritons and the electric field distributions in both nanostructures.

  • 122910. Yang, Liu
    et al.
    Kou, Pengfei
    Shen, Jianqi
    Lee, El Hang
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Zhejiang University, China.
    Proposal of a broadband, polarization-insensitive and high-efficiency hot-carrier schottky photodetector integrated with a plasmonic silicon ridge waveguide2015In: Journal of Optics, ISSN 2040-8978, E-ISSN 2040-8986, Vol. 17, no 12, article id 125010Article in journal (Refereed)
    Abstract [en]

    We propose a broadband, polarization-insensitive and high-efficiency plasmonic Schottky diode for detection of sub-bandgap photons in the optical communication wavelength range through internal photoemission (IPE). The distinctive features of this design are that it has a gold film covering both the top and the sidewalls of a dielectric silicon ridge waveguide with the Schottky contact formed at the gold-silicon interface and the sidewall coverage of gold can be easily tuned by an insulating layer. An extensive physical model on IPE of hot carriers is presented in detail and is applied to calculate and examine the performance of this detector. In comparison with a diode having only the top gold contact, the polarization sensitivity of the responsivity is greatly minimized in our photodetector with gold film covering both the top and the sidewall. Much higher responsivities for both polarizations are also achieved over a broad wavelength range of 1.2-1.6 mu m. Moreover, the Schottky contact is only 4 mu m long, leading to a very small dark current. Our design is very promising for practical applications in high-density silicon photonic integration.

  • 122911. Yang, Liu
    et al.
    Mo, Lei
    Chen, Tuo
    Forsberg, Erik
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Zhejiang Univ.
    A checkerboard selective absorber with excellent spectral selectivity2015In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 118, no 18, article id 183103Article in journal (Refereed)
    Abstract [en]

    A selective absorber with excellent spectral selectivity is proposed and analyzed. The absorber is based on a germanium (Ge) checkerboard on top of a tantalum (Ta) substrate. At wavelengths shorter than the 1.2 mu m cutoff, a very high absorption is achieved due to strong cavity resonances in the Ge nanosquares, and their interactions with adjacent nanocavities and the bottom Ta substrate. At longer wavelengths, absorption is greatly suppressed due to destructive interference between the transparent checkerboard layer and the highly reflective Ta substrate. To better describe the superior selectivity of our configuration, a new figure of merit (FOM) is introduced. We observe a FOM value of 0.88 compared to 0.69 for its planar counterpart. We also conduct a thermal analysis to verify the excellent selectivity of our absorber. A high temperature can be achieved and maintained, promising good potential for applications in solar thermophotovoltaic systems.

  • 122912.
    Yang, Liu
    et al.
    Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China.;Zhejiang Univ, Ningbo Res Inst, Ningbo 315100, Zhejiang, Peoples R China..
    Xu, Xinan
    Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China..
    Yuan, Yi
    Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China..
    Li, Zhihao
    Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China..
    He, Sailing
    KTH, School of Engineering Sciences (SCI), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China.;Zhejiang Univ, Ningbo Res Inst, Ningbo 315100, Zhejiang, Peoples R China.
    Meter-scale transparent conductive circuits based on silver nanowire networks for rigid and flexible transparent light-emitting diode screens2019In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 9, no 12, p. 4483-4496Article in journal (Refereed)
    Abstract [en]

    Meter-scale transparent conductive circuits based on silver nanowire (AgNW) networks are fabricated for transparent light-emitting diode (LED) screens on both rigid and flexible substrates. A 25-cm long AgNW transparent conductive strip is fabricated with a strip resistivity of 9.95 Omega/cm. A high uniformity is achieved in terms of film optical transmission (up to 84.5% in average) and sheet resistance (as low as 4.7 Omega/sq in average), superior to ITO. A transparent LED screen based on a 1.2-m ultralong AgNW circuit is demonstrated with LEDs emitting bright red, green and blue lights under different biases. The AgNW strip on a polyethylene terephthalate substrate shows mechanical flexibility and stable performance in bending tests. Based on this, a flexible transparent LED screen is proposed and presented. It works well when dynamically bent to a radius as small as similar to 15 mm. Therefore, the AgNW transparent conductive circuits are very promising as a replacement to ITO circuits for such smart screens, to be integrated into modern glass architectures and display videos in various public places.

  • 122913.
    Yang, Liunan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Heterogeneous MBS forwarder modeling and co-simulation2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The forwarder acts as an important role in mechanized Cut-to-Length timber harvesting system. But the majority of forwarder products on the market are not suspended or simply suspended by bogies which limit the riding quality of forwarder and result in soil damage due to large tireground interaction force. The Forestry Research Institute of Sweden is developing an active controlled pendulum arm suspension system actuated by hydraulic cylinders on the forwarder prototype named XT28. The aim of this active suspension system is to compensate the inherent shortcomings of the current suspension solutions. The thesis project focuses on implementing a heterogeneous simulation methodology which integrates the Multi-Body System model of XT28 built in MSC ADAMS/View with active suspension control model developed in MATLAB/Simulink. Thus, the co-simulation process is visualized in ADAMS/View. The results show that the active controlled pendulum arm suspension could improve the riding quality in a large extend and reduce the force between tire and ground at the same time. The cosimulation between ADAMS and Simulink is proved as a feasible and efficient approach to study the active control system for pendulum arm suspension on XT28 forwarder.

  • 122914.
    Yang, Liyun
    KTH, School of Technology and Health (STH).
    Development and validation of a novel iOS application for measuring arm inclination2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Work in demanding postures is a known risk factor for work-related musculoskeletal disorders (MSDs), specifically work with elevated arms may cause neck/shoulder disorders. Such a disorder is a tragedy for the individual, and costly for society. Technical measurements are more precise in estimating the work exposure, than observation and self-reports, and there is a need for uncomplicated methods for risk assessments. The aim of this project was to develop and validate an iOS application for measuring arm elevation angle.

    Such an application was developed, based on the built-in accelerometer and gyroscope of the iPhone/iPod Touch. The application was designed to be self-exploratory. Directly after a measurement, 10th, 50th and 90th percentiles of angular distribution and median angular velocity, and percentage of time above 30°, 60°, and 90° are presented. The focused user group, ergonomists, was consulted during the user interface design phase. Complete angular datasets may be exported via email as text files for further analyses.

    The application was validated by comparison to the output of an optical motion capture system for four subjects. The two methods correlated above 0.99, with absolute error below 4.8° in arm flexion and abduction positions. During arm swing movements, the average root-mean-square differences (RMSDs) were 3.7°, 4.6° and 6.5° for slow (0.1 Hz), medium (0.4 Hz) and fast (0.8 Hz) arm swings, respectively. For simulated painting, the mean RMSDs was 5.5°.

    Since the accuracy was similar to other tested field research methods, this convenient and “low-cost” application should be useful for ergonomists, for risk assessments or educational use. The plan is to publish this iOS application on Apple Store (Apple Inc.) for free. New user feedback may further improve the user interface.

  • 122915.
    Yang, Liyun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Ergonomic Risk Assessment and Intervention through Smart Workwear Systems2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The rapid development of wearable technology has provided opportunities to ergonomics research and practice with new ways for workload measurements, data analytics, risk assessment and intervention. This thesis aims at developing and evaluating methods using wearable technologies to assess physical risk factors at work, and further to give feedback to employees to improve their work techniques.

    One smartphone application (ErgoArmMeter) was developed for the assessment of upper arm postures and movements at work. The application uses integrated signals of the embedded accelerometer and gyroscope, and processes and presents the assessment results directly after a measurement. Laboratory validation with 10 participants was performed using an optical tracking system as standard measurement. The results showed that the application had similar accuracy compared to standard inclinometry for static postures and improved accuracy in dynamic conditions. With its convenience and low cost, the application may be used by researchers and practitioners in various scenarios for risk assessment.

    Three models for assessment of work metabolism (WM) using heart rate (HR) and accelerometers (ACCs) were evaluated during simulated work tasks with 12 participants against indirect calorimetry as standard measurement. The HR + arm-leg ACC model showed best accuracy in most work tasks. The HR-Flex model showed a small bias for the average of all tasks. For estimating WM in the field using wearable technologies, the HR-Flex model or the HR + arm-leg ACC model may be chosen depending on the need for accuracy level and resource availabilities. Further improvement of the classification algorithm in the HR + arm-leg ACC model is needed in order to suit various types of work.

    Two smart workwear systems were developed and evaluated. Smart workwear system 1.0 consisted of a sensorized vest, an inertial measurement unit (IMU) and an Android tablet application. It assessed risks of high physiological workload and prolonged occupational sitting/standing. The results were visualized by color-coded risk levels. The system was evaluated with 8 participants from four occupations in a field study. It was perceived as useful, comfortable and not disturbing by most participants. Further development is required for the system for automated risk assessment of various ergonomic risk factors in real work situations.

    Smart workwear system 2.0 consisted of an instrumented t-shirt with IMUs, vibration units and an Android smartphone application. It provided vibrotactile feedback to users’ upper arm and trunk when predefined angular thresholds were exceeded. The system was evaluated for work postures intervention in industrial order picking among 15 participants. It showed to be effective in improving the trunk and dominant upper arm postures. The system was perceived as comfortable and useful. The vibrotactile feedback was evaluated as supportive for learning regarding workplace and task design among the participants.

    In conclusion, the research in this thesis showed that wearable technologies can be used both in the laboratory and field for assessment of physical risk factors at work and intervention in work technique improvement. With further research and development, smart workwear systems may contribute to automated risk assessment, prevention of work-related ill health, and improvement of the design and overall quality of work.

  • 122916.
    Yang, Liyun
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Abtahi, Farhad
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Eklund, Jörgen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Hanson, Lars
    School of Engineering Science, University of Skövde.
    Lindecrantz, Kaj
    KTH.
    Forsman, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Carl, Lind
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Smart workwear system with real-time vibrotactile feedback for improving postural behaviour in industry2019In: From research to evidence based sustainable interventions and practices: Book of Abstracts, Bologna, Italy, 2019, p. 160-Conference paper (Refereed)
  • 122917.
    Yang, Liyun
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics. Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Borgström, D.
    Forsman, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics. Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Validation and comparison of three positioning protocols of inertial measurement units for measuring trunk movement2019In: 20th Congress of the International Ergonomics Association, IEA 2018, Springer, 2019, p. 205-211Conference paper (Refereed)
    Abstract [en]

    Postures and movements of the trunk are of ergonomic concern when evaluating the risks at work. Technical measurement methods can be used for measurements of trunk movements for long duration with high accuracy, and are therefore increasingly used in practice and research. However, currently there is no standardized protocol for the sensor placement for trunk measurement. Three placement protocols of inertial measurement units (IMUs), including placement on C7, T4 and sternum (St), in combination with S1 spinous process, were compared with an optical motion capture (OMC) system. Four subjects performed a movement test including forward to backward bending, sideward bending and twisting of the trunk, and a symmetrical lifting task. Root-mean-square differences (RMSDs) and Pearson’s correlation were calculated between the two systems. For the movement tests, the RMSDs of the forward inclination at the 10th, 50th and 90th percentiles from the three IMUs were all smaller than 7.3°. Larger differences were shown for C7 of the sideward inclination at 90th percentile (10.8°). Also for the twisting, larger differences were shown, especially for C7-S1 and T4-S1 (RMSD = 16.5° and 19.8°). For the lifting tests of forward inclination, St had the smallest differences compared to OMC (RMSDs < 4.1°), while slightly larger errors were found for C7 and T4 at the 90th percentile (RMSDs = 8.1° and 8.2°). Different positioning protocols seem to have a slightly different effect on the measurement accuracy of trunk movement. Considerations should be taken when comparing results across studies applying different protocols.

  • 122918.
    Yang, Liyun
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Grooten, W. J. A.
    Forsman, M.
    An iPhone application for upper arm posture and movement measurements2017In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 65, p. 492-500Article in journal (Refereed)
    Abstract [en]

    There is a need for objective methods for upper arm elevation measurements for accurate and convenient risk assessments. The aims of this study were (i) to compare a newly developed iOS application (iOS) for measuring upper arm elevation and angular velocity with a reference optical tracking system (OTS), and (ii) to compare the accuracy of the iOS incorporating a gyroscope and an accelerometer with using only an accelerometer, which is standard for inclinometry. The iOS-OTS limits of agreement for static postures (9 subjects) were -4.6° and 4.8°. All root mean square differences in arm swings and two simulated work tasks were <6.0°, and all mean correlation coefficients were >0.98. The mean absolute iOS-OTS difference of median angular velocity was <13.1°/s, which was significantly lower than only using an accelerometer (<43.5°/s). The accuracy of this iOS application compares well to that of today's research methods and it can be useful for practical upper arm measurements.

  • 122919.
    Yang, Liyun
    et al.
    KTH, School of Technology and Health (STH).
    Lu, Ke
    Abtahi, Farhad
    Lindecrantz, Kaj
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Seoane, Fernando
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Forsman, Mikael
    Institute of Environmental Medicine, Karolinska Institutet.
    Eklund, Jörgen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    A pilot study of using smart clothes for physicalworkload assessment2017In: JOY AT WORK, Lund, Sweden, 2017, p. 169-170Conference paper (Refereed)
  • 122920.
    Yang, Liyun
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Lu, Ke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Diaz-Olivares, Jose A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Seoane, Fernando
    Univ Boras, Swedish Sch Text, S-50190 Boras, Sweden.;Karolinska Inst, Inst Clin Sci Intervent & Technol, S-14157 Huddinge, Sweden.;Karolinska Univ Hosp, Dept Biomed Engn, S-14157 Huddinge, Sweden..
    Lindecrantz, Kaj
    Karolinska Inst, Inst Environm Med, S-17177 Stockholm, Sweden.;Univ Boras, Swedish Sch Text, S-50190 Boras, Sweden..
    Forsman, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics. nstitute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Abtahi, Farhad
    Karolinska Inst, Inst Environm Med, S-17177 Stockholm, Sweden..
    Eklund, Jörgen A. E.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Towards Smart Work Clothing for Automatic Risk Assessment of Physical Workload2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 40059-40072Article in journal (Refereed)
    Abstract [en]

    Work-related musculoskeletal and cardiovascular disorders are still prevalent in today's working population. Nowadays, risk assessments are usually performed via self-reports or observations, which have relatively low reliability. Technology developments in textile electrodes (textrodes), inertial measurement units, and the communication and processing capabilities of smart phones/tablets provide wearable solutions that enable continuous measurements of physiological and musculoskeletal loads at work with sufficient reliability and resource efficiency. In this paper, a wearable system integrating textrodes, motion sensors, and real-time data processing through a mobile application was developed as a demonstrator of risk assessment related to different types and levels of workload and activities. The system was demonstrated in eight subjects from four occupations with various workload intensities, during which the heart rate and leg motion data were collected and analyzed with real-time risk assessment and feedback. The system showed good functionality and usability as a risk assessment tool. The results contribute to designing and developing future wearable systems and bring new solutions for the prevention of work-related disorders.

  • 122921.
    Yang, Liyun
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics. IMM, Karolinska Institutet.
    Lu, Ke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Forsman, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics. IMM, Karolinska Institutet.
    Lindecrantz, Kaj
    Karolinska Institutet, Stockholm, Sweden; University of Borås, Borås, Sweden.
    Seoane, Fernando
    Ekblom, Örjan
    GIH, The Swedish School of Sport and Health.
    Eklund, Jörgen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Evaluation of physiological workload assessment methods using heart rate and accelerometry for a smart wearable system2019In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847, Vol. 62, no 5, p. 694-705Article in journal (Refereed)
    Abstract [en]

    Work metabolism (WM) can be accurately estimated by oxygen consumption (VO2), which is commonly assessed by heart rate (HR) in field studies. However, the VO2–HR relationship is influenced by individual capacity and activity characteristics. The purpose of this study was to evaluate three models for estimating WM compared with indirect calorimetry, during simulated work activities. The techniques were: the HR-Flex model; HR branched model, combining HR with hip-worn accelerometers (ACC); and HR + arm-leg ACC model, combining HR with wrist- and thigh-worn ACC. Twelve participants performed five simulated work activities and three submaximal tests. The HR + arm-leg ACC model had the overall best performance with limits of agreement (LoA) of −3.94 and 2.00 mL/min/kg, while the HR-Flex model had −5.01 and 5.36 mL/min/kg and the branched model, −6.71 and 1.52 mL/min/kg. In conclusion, the HR + arm-leg ACC model should, when feasible, be preferred in wearable systems for WM estimation.

  • 122922.
    Yang, Liyun
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Målqvist, Ingela
    Center for Occupational and Environmental Medicine, Stockholm County Council.
    Alderling, Magnus
    Center for Occupational and Environmental Medicine, Stockholm County Council.
    Carl, Lind
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics. Karolinska Institutet.
    Bergman Rentzhog, Annika
    Center for Occupational and Environmental Medicine, Stockholm County Council.
    Forsman, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics. Karolinska Institutet.
    Psychosocial health risk factors and perceived work ability in the home care sector2019In: Proceedings of the 2019 International Symposium on Human Factors and Ergonomics in Health Care, 2019Conference paper (Refereed)
  • 122923.
    Yang, Ludan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Chen, Qubo
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    NORDIC DEVELOPMENT FINANCE INSTITUTIONS IN AFRICA: ANALYSIS BASED ON THE CONTROL OF INVESTMENT THROUGH FUND2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nordic Development Finance Institutions (DFIs) play an important role in providing sustainable development for Africa which accordance with their mandates.  By investing in private equity Funds in Africa, investee companies have covered various sectors inAfricawhich may not only improve economic development but also increase employment. Additionally, investing in a Fund can spread risk through diversifications and help DFIs to share knowledge with Fund manager in local presence.

     

    This study analyzes the management control systems (MCS) of DFIs’ investing in private equity Funds, wherein we mainly focus on output control and behavior control which are two types of control widely discussed in previous research and literature. Hereby we set three hypotheses based on our research and get findings to support the research questions, which are:

    1.      DFIs use output control mechanism with contractual framework to secure their investment.

    Output control sets standards as to targets. It plays a fundamental role in the control process, as the contractual framework is short of standardized in private equity industry and Fund managers are selected strictly during screening process.

     

    2.      DFIs use behavior control to interact with Fund managers.

    Behavior control means appropriate instruction and guidelines imposed as results become foreseeable during the monitoring process. It becomes a central element where DFIs have to interact with Fund managers to track the investment progress & development effect, including investment decision making.

     

    3.      DFIs’ syndicated investment affects their control activities.

    Nordic DFIs’ investment strategy is making co-investment in Funds. When more parties are involved, the monitoring and control process become different compared with only one investor and it is affected by syndicated investment. While we did not deeply explore the control mechanism and process under syndication investment by either quantitative & qualitative method or case studying approach, we conclude that it does exist based on communication with interviewees.

     

    The word “Control” looks like a bureaucratic word. However, we found that Alignment is essential in control process for each partners while behavior control helps to assure the alignment. We think that control process become less difficult when previous strict selection of trust partner is successful. We suggest that the alignment between DFIs and other investors as well as Funds should be strengthened in the control process, so that investment objectives can be well realized.

     

    Besides Nordic DFIs, Africa also benefits from others such asChina’s “going global” strategy to encourage outward FDI. China-Africa Development Fund (CADFund) is the first Fund focused specially on large scale investment in Africa among Private Equity Funds inChina. China Development Bank (CDB) is the shareholder of CADFund, who provide resources and support to CADFund. By briefly comparing Nordic DFIs and CADFund, we found they use similar investment instruments and also similar strategies, such as investment in less developed countries inAfricato improve economic conditions, support home companies investing in Africa etc. Including an analysis on CAD as well as the comparison with Nordic DFIs not only strengthen the understanding of DFIs’ activities in Africa, but also clarify the different investment characteristics of Western and Eastern investors in Africa. We also suggest that Nordic DFIs and CADFund can share experience and knowledge to promote sustainable development for Africa.

     

     

  • 122924. Yang, M.
    et al.
    Lu, J.
    Wang, Yuli
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Gong, C.
    Yan, L.
    Analysis of eddy viscosity models in predicting flow field of high-speed water jet2014In: Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery, ISSN 1000-1298, Vol. 45, no 7, p. 306-312Article in journal (Refereed)
    Abstract [en]

    Three commonly used two-equation turbulence models were adopted. The computed velocity field was compared with the data from corresponding laser Doppler anemometer measurement to analyze the accuracy of these models. By adjusting the model parameters, the simulation data can fit into the experimental result. The optimal viscosity coefficients Cμ in these used eddy viscosity models were presented. It is shown that the RNG k-ε model is more sensitive to Cμ, while the results from Standard k-ε model vary almost linearly with the change of the Cμ value. Study on the simulated flow field gives that if the peak of turbulence kinetic energy appears within the radial span, it will affect the velocity distribution along the jet axis; otherwise, it will modify the velocity magnitude. The proposed numerical scheme reduces the physical complexities involved in ultra-high pressure injection process so that it can be applied to archive fast production from relevant CAE workflow.

  • 122925. Yang, M.
    et al.
    Yan, L.
    Wang, Yuli
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    Gong, C.
    Lu, J.
    Instability and interfacial coherent structure of free round turbulent jet2016In: Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery, ISSN 1000-1298, Vol. 47, no 2, p. 35-44Article in journal (Refereed)
    Abstract [en]

    As a basic flow form, free round turbulent jet has been used in various industry fields such as water jet cutting, water cleaning, fuel spray, etc. To understand the development of jet and some of its underlying characteristics, it is crucial that the mechanism of jet instability should be recognized. A robust two-phase flow large eddy simulation (LES) algorithm was applied to predict the liquid instability and the coherent structure of free round turbulent jet. The main objective was to characterize the liquid instability mechanism without resorting stability analysis. Special attention was focused on how the instability and the eddy structure in the near field of round jet were affected by the imposed inlet velocity and disturbance. In this respect, the cases within the range of Re=10000~80000 at various disturbance intensities were tested. Results revealed that the velocity and disturbances played an important role in the stability of liquid jet. The unperturbed liquid core length and scale of surface wave were decreased, and a wide variety of vortexes were produced in the near field of jet with velocity and disturbance intensity increased. The decay rates of average velocity along the central axis of jet were similar under different disturbance intensities at the same Reynolds number (or different Reynolds numbers at the same disturbance intensity). The positive entrainment was enhanced and the radial spread of the jet along the streamwise became more significant with the Reynolds number increased.

  • 122926.
    Yang, Miao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Radiation Induced Processes at Solid-Liquid Interfaces2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the thesis, the reactions between water radiolysis products—H2O2, HO• and O2—with metals and metal oxides utilized in nuclear industry are studied. The reactions include not only surface reactions, e.g. redox reactions and catalytic decomposition of H2O2, but also solution reactions (Haber-Weiss reactions). To study the interfacial reactions, it is crucial to monitor the dissolution of the solid material, reactivity of H2O2 and formation of the intermediate hydroxyl radicals.Hydroxyl radicals are captured by probe (Tris or methanol) to generate CH2O which can be quantified by the modified Hantzsch method. The results from γ-irradiation experiments on homogeneous system show that the conversion yield of CH2O from hydroxyl radicals is affected by O2 and pH. A mechanism of CH2O production from Tris is proposed.Besides, the consumption rate of H2O2 in the H2O2/ZrO2/Tris system is found to be influenced by Tris. A mechanism for the catalytic decomposition of H2O2 upon ZrO2 surface is proposed which includes independent surface adsorption sites for H2O2 and Tris. Moreover, it is demonstrated that the deviation of detected CH2O concentration by the modified Hantzsch method from actual concentration increases with increasing [H2O2]0/[CH2O]0.The inhibition of sulfide on the radiation induced dissolution of UO2 is confirmed and is dependent on sulfide concentration. And the inhibition of sulfide is independent to that of H2/Pd.It is found that the reactivity of H2O2 and dynamics of CH2O formation are different for the studied materials in the H2O2/MxOy/Probe system. The kinetic parameters, such as rate constant, activation energy, frequency factors are determined.Both surface and solution reactions are observed in the aqueous W(s)/H2O2/Tris system. It is also demonstrated that Haber-Weiss reactions which produce HO• continuously are dominating. Furthermore, it is found that hydroxyl radicals are formed simultaneously during the dissolution of W in aerobic aqueous system.The knowledge conveyed by the thesis is relevant to nuclear technological applications, as well as the applications related in photocatalysis, biochemistry, corrosion science, catalysis and optics/electronics.

  • 122927.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry (closed 20110630).
    Barreiro Fidalgo, Alexandre
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry (closed 20110630).
    Nilsson, Sara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry (closed 20110630).
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry (closed 20110630).
    Inhibition of radiation induced dissolution of UO2 by sulfide: a comparision with the hydrogen effect2011Manuscript (preprint) (Other academic)
  • 122928.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Barreiro Fidalgo, Alexandre
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sundin, Sara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Inhibition of radiation induced dissolution of UO2 by sulfide-A comparison with the hydrogen effect2013In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 434, no 1-3, p. 38-42Article in journal (Refereed)
    Abstract [en]

    In this work we have studied the influence of H2S on radiation induced dissolution of spent nuclear fuel using simple model systems. The reaction between H2O2 and H2S/HS- has been studied experimentally as well as the effect of H2S/HS - on γ-radiation induced dissolution of a UO2 pellet. The experiments clearly show that the reaction of H2O 2 and H2S/HS- is fairly rapid and that H 2O2 and H2S/HS- stoichiometry is favorable for inhibition. Radiolysis experiments show that H2S/ HS- can effectively protect UO2 from oxidative dissolution. The effect depends on sulfide concentration in combination with dose rate. Autoclave experiments were also conducted to study the role of H 2S/HS- in the reduction of U(VI) in the presence and absence of H2 and Pd particles in anoxic aqueous solution. The aqueous solutions were pressurized with H2 or N2 and two different concentrations of H2S/HS- were used in the presence and absence of Pd. No catalytic effect of Pd on the U(VI) reduction by H2S/HS- could be found in N2 atmosphere. U(VI) reduction was found to be proportional to H2S/HS- concentration in H2 and N2 atmosphere. It is clearly shown the Pd catalyzed H2 effect is more powerful than the effect of H2S/HS-. H2S/HS- poisoning of the Pd catalyst is not observed under the present conditions.

  • 122929.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Evaluation of the O-2 and pH Effects on Probes for Surface Bound Hydroxyl Radicals2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 15, p. 7971-7979Article in journal (Refereed)
    Abstract [en]

    Interfacial reactions between H2O2 and metal oxides are important in several fields but are yet not fully understood. Recently, tris(hydroxymethyl)aminomethane (Tris) was used as a probe in detecting the intermediate hydroxyl radical (HO center dot) during such process via the formation of formaldehyde (CH2O). In this work, we evaluate two probes (methanol and Tris) for detection of surface bound HO center dot by investigating the O-2 and pH effects on the production of formaldehyde. Moreover, we also examine the pH effect on the production of formaldehyde from Tris in the catalytic decomposition of H2O2 on ZrO2. The influence of O-2 and pH on the yield of formaldehyde under homogeneous conditions was studied via gamma-radiolysis of water. The solution was either deoxygenated or saturated with gas containing 20% 02, and the pH was ranging from 7.0 to 9.0. In the gamma-radiolysis experiment, O-2 shows a strong impact on the yield of formaldehyde: 14-68% for methanol and 16-29% for Tris. However, during the catalytic decomposition of H2O2, O-2 only enables a 30% enhancement of the production of CH2O when using Tris as the scavenger. While for methanol, the O-2 effect is almost negligible, and the production of CH2O from Tris is much higher than that from methanol. For practical reasons, only Tris was studied when evaluating the pH effect. A significant increase in the production of formaldehyde is observed by increasing pH during gamma-radiolysis of water while an even more pronounced pH-dependent increase is observed in the catalytic decomposition of H2O2 on ZrO2. The former indicates that the scavenging yield is base-catalyzed while the latter indicates that the formation of HO center dot is also base-catalyzed. On the basis of the observed effects of O-2 and pH, we propose a mechanism for the production of formaldehyde from Tris. The mechanism accounts for the observed impacts of O-2 and pH on the yield of formaldehyde.

  • 122930.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Surface reactivity of hydroxyl radicals formed upon catalytic decomposition of H2O2 on ZrO22015In: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 400, p. 49-55Article in journal (Refereed)
    Abstract [en]

    In this work, the surface reactivity of hydroxyl radicals formed upon catalytic decomposition of H2O2 on ZrO2 in the presence of Tris(hydroxymethyl) aminomethane was studied experimentally. Two sets of competition experiments were performed: the competition between H2O2 and Tris for the surface bound hydroxyl radical (HO) and between O2 and H2O2 for the hydroxymethyl radical (CH2OH) (precursor for formaldehyde). A 5-fold increase in initial concentration of Tris or H2O2 does not lead to a 5-fold increase in CH2O formation (only by a factor of 2-3 in the studied concentration range). The O2-dependent enhancement of the final production of CH2O becomes weaker upon increasing the initial concentration of H2O2 from 0.5 mM to 5 mM. The final production of CH2O becomes independent of the concentration of Tris when [Tris]0 is above 100 mM, i.e., the surface is saturated with Tris at this concentration. Based on the experimental results, a site-specific mechanism of H2O2 decomposition on the surface of ZrO2 was proposed. This model was used for numerical simulations of the dynamics of the reaction system. The kinetics was simulated using the kinetic simulation software Gepasi 3.0 and the results are in good agreement with the experimental observations.

  • 122931.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Wuhan University of Technology, China.
    Soroka, Inna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Exploring the limitations of the Hantzsch method used for quantification of hydroxyl radicals in systems of relevance for interfacial radiation chemistry2017In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 130, p. 1-4Article in journal (Refereed)
    Abstract [en]

    In the presence of Tris or methanol, hydroxyl radicals in systems of relevance for interfacial radiation chemistry can be quantified indirectly via the Hantzsch method by determining the amount of the scavenging product formaldehyde formed. In this work, the influence of the presence of H2O2 on the Hantzsch method using acetoacetanilide (AAA) as derivatization reagent is studied. The experiments show that the measured CH2O concentration deviates from the actual concentration in the presence of H2O2 and the deviation increases with increasing [H2O2]0/[CH2O]0. The deviation is negative, i.e., the measured formaldehyde concentration is lower than the actual concentration. This leads to an underestimation of the hydroxyl radical production in systems containing significant amount of H2O2. The main reason for the deviation is found to be three coupled equilibria involving H2O2, CH2O and the derivative produced in the Hantzsch method.

  • 122932.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Soroka, Inna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hydroxyl Radical Production in Aerobic Aqueous Solution containing Metallic TungstenManuscript (preprint) (Other academic)
  • 122933.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Soroka, Inna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hydroxyl radical production in aerobic aqueous solution containing metallic tungsten2015In: Catalysis communications, ISSN 1566-7367, E-ISSN 1873-3905, Vol. 71, p. 93-96Article in journal (Refereed)
    Abstract [en]

    Abstract In this work, we investigate the production of hydroxyl radicals from the W(s)/air aqueous system by quantifying the amount of scavenging product formaldehyde via the modified Hantzsch method. Tris(hydroxymethyl) aminomethane (Tris) and methanol are used as probe for HO. Meanwhile, the amount of dissolved tungsten is determined by ICP-OES. A turnover point ([W] ≈ 200 μM) is observed in the Tris case after which the production rate of CH2O overwhelms the constant rate in the methanol case. Based on the results, a mechanism is proposed for the studied system including both surface and solution reactions.

  • 122934.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Soroka, Inna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Influence of H2O2 on the Quantitative Determination of Formaldehyde using Acetoacetanilide as Detection Reagent in the Hantzsch MethodManuscript (preprint) (Other academic)
  • 122935.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Zhang, Xian
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Grosjean, Alex
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Soroka, Inna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kinetics and Mechanism of Reactions between H2O2 and Tungsten PowderManuscript (preprint) (Other academic)
    Abstract [en]

    In this work, the reaction between H2O2 and tungsten powder in the presence of Tris(hydroxymethyl) aminomethane was studied experimentally. The production of hydroxyl radicals can be quantified indirectly by quantifying the scavenging product formaldehyde (CH2O). XRD, XPS and SEM analysis shows that no significant structural or compositional changes occur after reaction. We compared H2O2 consumption and CH2O formation in both heterogeneous W(s)/H2O2/Tris system and homogenous W(aq)/H2O2/Tris system. Increasing the amount of W powder leads to the increase in dissolution rate of W species, insignificant increase of H2O2 consumption rate and the decrease of final CH2O production. By contrast, the consumption rate of H2O2 increases as increasing the concentration of dissolved W species. Based on the experimental results, a mechanism of H2O2 reacting with W powder in the presence of Tris is proposed. The mechanism well explained the relationship between surface reactions and homogeneous Haber-Weiss reactions.

  • 122936.
    Yang, Miao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Zhang, Xian
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Grosjean, Alex
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Soroka, Inna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kinetics and Mechanism of the Reaction between H2O2 and Tungsten Powder in Water2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 39, p. 22560-22569Article in journal (Refereed)
    Abstract [en]

    In this work, the reaction between H2O2 and tungsten powder in the presence of Tris(hydroxymethyl) aminomethane was studied experimentally. The production of hydroxyl radicals can be quantified indirectly by quantifying the scavenging product formaldehyde (CH2O). XRD, XPS, and SEM analysis shows that no significant structural or compositional changes occur after reaction. We compared H2O2 consumption and CH2O formation in both heterogeneous W(s)/H2O2/Tris system and homogeneous W(aq)/H2O2/Tris system. Increasing the amount of W powder leads to the increase in dissolution rate of W species, insignificant increase of H2O2 consumption rate and the decrease of final CH2O production. By contrast, the consumption rate of H2O2 increases as increasing the concentration of dissolved W species. Based on the experimental results, a mechanism of H2O2 reacting with W powder in the presence of Tris is proposed. The mechanism well explained the relationship between surface reactions and homogeneous Haber–Weiss peroxide chain breakdown.

  • 122937.
    Yang, Ming
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Numerical Modeling of Aluminum Sampling Process2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Castings of aluminum alloys are widely used in the automotive and aerospace industries since they play a significant role in improving the performance and fuel efficiency. In aluminum industries, sampling is the most common method to evaluate the inclusion levels which is a key indicator for the quality of the aluminum alloys. Since how the filling process and solidification process will influence the inclusion characteristics during the sampling procedure is of great importance, the objectives of this work is to create a the two-phase flow model to simulate the filling process and solidification process, as well as calculate the particles movement in the whole sampling procedure.

    Computational Fluid Dynamics (CFD) modeling was used and this work was performed in the software ANSYS FLUENT. A numerical two dimensional (2D) axisymmetric model was built to simulate the sampling procedure with the assumption that the filling could be done along the main axis automatically. First, the initial solidification during the filling was taken into account without particle injection. The realizable k − ε turbulence model was used to model the effects of the turbulence. Several simulations with different inlet filling rate, different initial filling temperature and different inlet diameter was calculated to see the influence on the solidification behavior. Then, the whole sampling system was modeled with particle injection. The Discrete Phase Model (DPM) was used to simulate the particle motion in the melt and the focus was on the influence of the initial solidification on the inclusion distributions. Finally, the optimal sampling position inside the aluminum sampler mold was calculated.

  • 122938.
    Yang, Mingzhao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Attempts to improve the performance properties of gluten polymer2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study presents ways to improve performance properties of wheat gluten (WG) polymers. One was to improve the water/moisture resistance. The method was to protect flexible WG films against water or moisture by coating it with polyethylene terephthalate (PET) film and a diamine (Jeffamine®) was used as a coupling agent to manufacture PET-coated films. The strength of bonding between the gluten polymer and PET was strong for the samples using 15 wt % and 20 wt% diamin, but weak for that with 5 wt% diamin. Moreover, Infrared spectroscopy indicated that the Jeffamine® and glycerol had penetrated the PET layer over time.

  • 122939. Yang, N.
    et al.
    Wang, W. -X
    KTH.
    Wang, F. -P
    Xue, B. -Y
    Wang, K.
    KTH.
    Road information change detection based on fractional integral and neighborhood FCM2018In: Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition), ISSN 1671-8879, Vol. 38, no 2, p. 103-111Article in journal (Refereed)
    Abstract [en]

    In order to improve the accuracy of road information change detection, a new road information change detection method based on fractional integral and spatial neighborhood fuzzy C-means (FCM) algorithm was presented. Firstly, a new difference image was generated by the gray difference calculation of the dual phase remote sensing images after registration and geometric correction. Then, a smaller fractional integral order was used to construct the denoising image mask with eight directions on the upper and lower, left and right, and four diagonals, and the fractional integral calculation were applied to the difference images, which improved the image signal-to-noise ratio (SNR) while preserving the edge and texture details of the image. Finally, the FCM clustering method combined with neighborhood spatial information was used to calculate the difference image after denoising. The highest and lowest points of the difference image gray values were selected as the center point of cluster initialization. The Euclidean Metric of the neighborhood were used to depict different weight values, so as to characterize the influence degree of domain pixels on central pixels and eliminate invalid isolated points. Detecting probability, false alarm rate and missed alarm rate of the algorithm were evaluated by the experiment. The results show that FCM road information change detection method based on fractional integral and neighborhood spatial information can effectively extract road change information. When the integral fractional order is 0.2, the FCM smoothing parameter is 2.5, the detection probability is higher than the comparison algorithm by 18% to 46%, the false alarm rate is lower than the comparison algorithm by 15% to 38%, and the missed alarm rate is lower than the comparison algorithm by 3% to 7%. The present algorithm can achieve better results in suppressing noise information and enhancing texture details. Especially, when the center pixel is noise, due to the introduction of neighborhood information, and it is affected by the neighborhood normal pixels. The proposed method could avoid misclassification by adjusting the membership automatically, it can effectively suppress the influence of neighborhood noise points on the normal pixel classification, and reduce the false alarm rate. 2 tabs, 4 figs, 28 refs. 

  • 122940. Yang, Perry Pei-Ju
    et al.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Modeling Urban Design with Energy Performance2016In: CUE 2015 - APPLIED ENERGY SYMPOSIUM AND SUMMIT 2015: LOW CARBON CITIES AND URBAN ENERGY SYSTEMS, 2016, p. 3-8Conference paper (Refereed)
    Abstract [en]

    Traditional urban design methods focus on the form-making process and lack performance dimensions such as energy efficiency. There are inherent differences between Urban Design as a model of decision-making for choosing form alternatives and Energy System Modeling as a model of evaluating and assessing system functions. To design a high energy performance city, the gap between the two models must be bridged. We propose a research design that combines the Urban Design Computational Model (UDCM) and the Optimization Model of Energy Process (OMEP) to demonstrate how an urban design computation can be integrated with an energy performance process and system. An evidence-based case study of community-level near zero energy districts will be needed for future work.

  • 122941.
    Yang, Ping
    et al.
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Yue
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Guan, Yong Liang
    Nanyang Technol Univ, Sch Elect & Elect Engn, Singapore 639798, Singapore..
    Li, Shaoqian
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiang, Wei
    James Cook Univ, Coll Sci & Engn, Cairns, Qld 4878, Australia..
    Adaptive Spatial Modulation MIMO Based on Machine Learning2019In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 9, p. 2117-2131Article in journal (Refereed)
    Abstract [en]

    In this paper, we propose a novel framework of low-cost link adaptation for spatial modulation multiple-input multiple-output (SM-MIMO) systems-based upon the machine learning paradigm. Specifically, we first convert the problems of transmit antenna selection (TAS) and power allocation (PA) in SM-MIMO to ones-based upon data-driven prediction rather than conventional optimization-driven decisions. Then, supervised-learning classifiers (SLC), such as the K-nearest neighbors (KNN) and support vector machine (SVM) algorithms, are developed to obtain their statistically-consistent solutions. Moreover, for further comparison we integrate deep neural networks (DNN) with these adaptive SM-MIMO schemes, and propose a novel DNN-based multi-label classifier for TAS and PA parameter evaluation. Furthermore, we investigate the design of feature vectors for the SLC and DNN approaches and propose a novel feature vector generator to match the specific transmission mode of SM. As a further advance, our proposed approaches are extended to other adaptive index modulation (IM) schemes, e.g., adaptive modulation (AM) aided orthogonal frequency division multiplexing with IM (OFDM-IM). Our simulation results show that the SLC and DNN-based adaptive SM-MIMO systems outperform many conventional optimization-driven designs and are capable of achieving a near-optimal performance with a significantly lower complexity.

  • 122942.
    Yang, Ping
    et al.
    Univ Elect Sci & Technol China, Ctr Intelligent Networking & Commun, Chengdu 611731, Sichuan, Peoples R China.;Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Yue
    Univ Elect Sci & Technol China, Ctr Intelligent Networking & Commun, Chengdu 611731, Sichuan, Peoples R China.;Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Ma, Zheng
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    NOMA-Aided Precoded Spatial Modulation for Downlink MIMO Transmissions2019In: IEEE Journal on Selected Topics in Signal Processing, ISSN 1932-4553, E-ISSN 1941-0484, Vol. 13, no 3, p. 729-738Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel multi-user multiple-input multiple-output (MIMO) transmission scheme, called non-orthogonal multiple access (NOMA) aided precoded spatial modulation (PSM) (NOMA-PSM) is proposed for overloaded downlink transmissions. NOMA-PSM beneficially amalgamates the concept of index modulation (IM) and NOMA techniques, and therefore it inherits both the merits of IM with low-complexity transceiver and the advantages of NOMA with high bandwidth efficiency. For the proposed scheme, we develop a pair of low-complexity yet effective detection algorithms by combining the spatial index demodulation and successive interference cancelation. The spectral efficiency (SE), implementation cost, and multi-user interference of NOMA-PSM are evaluated and compared with conventional designs. Furthermore, we derive the mutual information (MI) of the proposed NOMA-PSM to characterize its achievable SE and also obtain a lower bound for simplifying the measurement of MI. Our simulation results show that the proposed NOMA-PSM scheme is capable of achieving considerable performance gains over conventional orthogonal multiple access aid PSM and antenna-groupingbased PSM in wireless MIMO fading channels.

  • 122943.
    Yang, Ping
    et al.
    Univ Elect Sci & Technol China, Ctr Intelligent Networking & Commun, Chengdu 611731, Sichuan, Peoples R China.;Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Yue
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Zhu, Jing
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Li, Shaoqian
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiang, Wei
    James Cook Univ, Coll Sci & Engn, Cairns, Qld 4878, Australia..
    Enhanced Receive Spatial Modulation Based on Power Allocation2019In: IEEE Journal on Selected Topics in Signal Processing, ISSN 1932-4553, E-ISSN 1941-0484, Vol. 13, no 6, p. 1312-1325Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate the benefits of power allocation (PA) for multiple-input multiple-output (MIMO) receive spatial modulation (RSM) with both a total transmit power constraint (TTPC) and a per-antenna power constraint (PAPC). First, we derive optimal PA closed-form solutions that maximize the minimum distance d(min) between the received signal points for (N-t x 2)-element RSM with arbitrary phase-shift keying schemes (where N-t is the number of transmit antennas) subject to a TTPC. Based on the derived solutions and the error vector reduction (EVR) method, we propose a low-complexity iterative algorithm to identify PA parameters for high numbers of receive antennas (N-r >= 2). Specifically, the EVR-based PA (EVR-PA) algorithm resembles its traditional exhaustive-search-based counterpart, but only exploits the receive distances of a few dominant error vectors to iteratively optimize the PA matrix. Then, a more strict yet practical PAPC is considered for PA in RSM-MIMO systems, and a well-designed approximate convex optimization (ACO)-based iterative PA algorithm is proposed. Compared to EVR-PA, the ACO-based PA (ACO-PA) algorithm first formulates the PA problems with the PAPC in RSM into constrained quadratic program problems and then utilizes the powerful augmented Lagrangian multiplier to find their optimal solutions. Our simulation results show that the proposed EVR-PA- and ACO-PA-aided RSM schemes outperform the equal-power-allocated RSM- and PA-aided spatial multiplexing schemes.

  • 122944.
    Yang, Qigui
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Theoretical study of Gd2O3-CeO2 (111) interface2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Atomistic modelling has widely been applied for studying structures and properties of materials. There are various methods to perform atomistic modelling. This master thesis presents a combined density functional theory (DFT) and cluster expansion (CE) study of Gd2O3 and Gd2O3-CeO2 interface (GCI) relevant for solid oxide fuel cells (SOFCs).

       The energy differences (ΔE) of Va-O exchanges in C-type Gd2O3 and at GCI are calculated using both DFT and CE methods. We also calculated the migration energy (Emig) of Va jumps in Gd2O3 and at GCI by DFT. The comparison between the CE and DFT results demonstrates that the CE method provides a relatively accurate estimation of ΔE while it requires less computational resources. Furthermore, the CE method is used to study the Va migration in the vicinity of the Gd2O3-CeO2 interface. The potential energy landscapes of different types of paths are studied.

  • 122945.
    Yang, Qiongyuan
    KTH, School of Information and Communication Technology (ICT).
    The Practical Study of Optimizing and Commercializing Mobile Value Added Service in China2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the fast development of mobile communication technology, mobile value added service (VAS) kept booming, the maturation of the mobile payment solutions also promoted the industry to become more consummate and profitable. As the cost of duplicating e-products is low while the return on investment is considerable high in this industry, many mobile VAS company are searching for bigger and challenging market such as China. The general aim of this thesis project is to provide practical solutions for these companies to successfully enter into the Chinese market.

    To fulfill this goal, the thesis studied behavior patterns of Chinese mobile VAS users by questionnaires, results indicated that variables and factors assessed in this study can significantly affect customers’ consume behaviours. Furthermore feasible business models and corresponding cooperative strategies were proposed and discussed in perspectives of value network, profitability and product control, which are tightly correlated to the commercialization of product. Moreover, this thesis introduced different marketing strategies to support the implementation of business models and introduced open and closed innovation conceptions for strategic development of mobile VAS companies’ growth in future.

  • 122946.
    Yang, Qirui
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Impacts on sustainable development of two CDM projects: A comparison using AHP method2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays the mitigation of climate change and the reduction of greenhouse gases are one of the priorities in the international affairs. Clean Development Mechanism (CDM) is one of the products generated according to this request. For China, CDM brings advanced technologies in terms of energy saving and emission reduction, and driving forces for sustainable development, hereby the development of CDM projects is in full swing in China so far. However, it is not easy to decide which type of CDM projects is suitable for a certain city or region, which project contributes more to sustainable development compared with others, when it comes to several alternatives. In this case, decision-makers require a tool to help make a rational decision. As one of the approaches of assisting in making decisions, the Analytic Hierarchy Process (AHP) is able to provide assistance for decision-makers to compare the contribution of discrepant CDM projects to sustainable development. Moreover, a case study is taken between two typical CDM projects: HFC23 decomposition project and small-scale hydropower project, so as to check if AHP is useable. The result of the case study

    indicates that HFC23 decomposition project contributes more than small-scale hydropower plant project to sustainable development, which is not in line with China’s CDM development trend for these two projects (NCCCC, 2005), due to the different represented interests of the study group and the real decision-makers. Nevertheless, the result is rational and valid since there is nothing wrong with the AHP method and its application. In addition, in order to improve the effect of assisting in decision making, AHP was tried to be improved in three respects: impairing subjectiveness, avoiding rank reversal and improving accuracy. Even though for AHP itself, DEA/AHP approach could successfully eliminate the subjectiveness, however when it comes to this very case: compare CDM projects in terms of contribution to sustainable development in China, it cannot play an effective role. Moreover, PCA/AHP method cannot eliminate the subjectiveness at the root either. The framework method provides a possibility in theory to increase objectiveness. Two expects provided a feasible way to avoid rank reversal in their article, and the two pathways of improving results accuracy mentioned in this thesis are considered inappropriate in this case. On the other side, concerning AHP application, how to covert realistic issues to AHP structure, how to get desirable initial information, and how to avoid limitation generated by considerable criteria, sub-criteria and alternatives are considered as the difficulties which should be paid attention. In future, AHP could be applied frequently and effectively concerning providing assistance in making decisions in China, if the stakeholders as many as possible are involved in decision-making process.

  • 122947. Yang, Quanling
    et al.
    Saito, Tsuguyuki
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Isogai, Akira
    Cellulose nanofibrils improve the properties of all-cellulose composites by the nano-reinforcement mechanism and nanofibril-induced crystallization2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 42, p. 17957-17963Article in journal (Refereed)
    Abstract [en]

    All-cellulose nanocomposite films containing crystalline TEMPO-oxidized cellulose nanofibrils (TOCNs) of 0-1 wt% were fabricated by mixing aqueous TOCN dispersions with alkali/urea/cellulose (AUC) solutions at room temperature. The mixtures were cast on glass plates, soaked in an acid solution, and the regenerated gel-like films were washed with water and then dried. The TOCN did not form agglomerates in the composites, and had the structure of TOCN-COOH, forming hydrogen bonds with the hydroxyl groups of the regenerated cellulose molecules. X-ray diffraction analysis revealed that the matrix cellulose molecules increased the cellulose II crystal size upon incorporation of TOCN. As a result, the TOCN/AUC composite films had high Young's modulus, tensile strength, thermal stability and oxygen-barrier properties. The TOCN/AUC composite films are promising all-cellulose nanocomposites for versatile applications as new bio-based materials.

  • 122948. Yang, Sheng-Chun
    et al.
    Wang, Yong-Lei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jiao, Gui-Sheng
    Qian, Hu-Jun
    Lu, Zhong-Yuan
    Accelerating electrostatic interaction calculations with graphical processing units based on new developments of ewald method using non-uniform fast fourier transform2016In: Journal of Computational Chemistry, ISSN 0192-8651, E-ISSN 1096-987X, Vol. 37, no 3, p. 378-387Article in journal (Refereed)
    Abstract [en]

    We present new algorithms to improve the performance of ENUF method (F. Hedman, A. Laaksonen, Chem. Phys. Lett. 425, 2006, 142) which is essentially Ewald summation using Non-Uniform FFT (NFFT) technique. A NearDistance algorithm is developed to extensively reduce the neighbor list size in real-space computation. In reciprocal-space computation, a new algorithm is developed for NFFT for the evaluations of electrostatic interaction energies and forces. Both real-space and reciprocal-space computations are further accelerated by using graphical processing units (GPU) with CUDA technology. Especially, the use of CUNFFT (NFFT based on CUDA) very much reduces the reciprocal-space computation. In order to reach the best performance of this method, we propose a procedure for the selection of optimal parameters with controlled accuracies. With the choice of suitable parameters, we show that our method is a good alternative to the standard Ewald method with the same computational precision but a dramatically higher computational efficiency.

  • 122949.
    Yang, Shu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    CFD Investigation of aeromechanic FORCING sensitivity for a generic transonic turbine2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Aeromechanic problems occur in various disciplines, the research here is focused on turbomachinery.  Advanced design criteria and accurate prediction methods for aeromechanic problems such as forced response and flutter become increasingly important with the present demand in turbomachine engine development towards lighter, cheaper, more efficient and reliable turbomachines. The aeromechanic analysis made at a late stage in the design process plays a crucial role to avoid failures. The present work aims at getting a better understanding of the aerodynamic mechanisms in transonic turbine stages and further development of numerical methods for stator-rotor interaction predictions.

     

    In this work standard industry tools are used for forced response computations for a one stage transonic high pressure turbine. Different configurations namely a tip shroud cavity, a hub cavity and external purge flow have been studied numerically to evaluate the influences on blade forcing predictions. CFD results are compared for all the cases with different features in both steady and unsteady state. Blade loading and integrated blade forcing are examined and physical interpretations of flow field features are given.

     

    The investigation shows that including detailing features has a significant influence on the aerodynamic forcing. Leakage flow going through the tip shroud cavity is approximately 4.0% of the main passage flow. The first harmonic of rotor circumferential forcing is reduced by 19.8% when including the hub cavity. The tip shroud cavity feature tends to increase the unsteady aerodynamic forcing for the rotor blade despite of the slightly different operating conditions. The external purge flow has been proven to have a relative difference of 1.1% on the rotor blade forcing. The change in forcing is considered to arise from the interaction between the cavity flow and the main passage flow. 

  • 122950. Yang, Shucai
    et al.
    Liu, Weiwei
    Ji, Wei
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. Harbin University of Science and Technology, China.
    Liu, Xianli
    Zhu, Jie
    A novel method of experimental evaluation on BTA tool geometries2017In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 91, no 9-12, p. 4253-4261Article in journal (Refereed)
    Abstract [en]

    Towards the problem of closed space of Boring and Trepanning Association (BTA) drill, this paper presents a novel experimental method to evaluate BTA tool geometries, and a turning-based test is conducted to simulate drilling. The three inserts of BTA drill are replaced by the three turning inserts, the rotation of BTA drill is transformed by workpiece rotation in turning, the feed of BTA drill changes into the feed of turning inserts, and the cutting area per BTA insert is simulated by the cutting depth in turning. To implement the approach, three angles, consisting of edge inclination, flank angle and edge declination, are organised by a three-factor and three-level Taguchi experiment for each BTA insert, e.g. outside insert, centre insert and middle insert. Cutting force, chip patterns and chip curl radius are observed and measured to evaluate the insert geometries.

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