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  • 2801.
    Ahmed, Mona
    et al.
    Karolinska Inst, Dept Mol Med & Surg, Ctr Mol Med, S-17176 Stockholm, Sweden..
    Gustafsson, Björn
    Karolinska Inst, Dept Mol Med & Surg, Ctr Mol Med, S-17176 Stockholm, Sweden..
    Aldi, Silvia
    Karolinska Inst, Sect Med Inflammat Res, Dept Med Biochem & Biophys, S-17177 Stockholm, Sweden..
    Dusart, Philip
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Egri, Gabriella
    Surflay Nanotec GmbH, Max Planck Str 3, D-12489 Berlin, Germany..
    Butler, Lynn M.
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics.
    Bone, Dianna
    Karolinska Inst, Dept Mol Med & Surg, Ctr Mol Med, S-17176 Stockholm, Sweden..
    Dahne, Lars
    Surflay Nanotec GmbH, Max Planck Str 3, D-12489 Berlin, Germany..
    Hedin, Ulf
    Karolinska Inst, Dept Mol Med & Surg, Ctr Mol Med, S-17176 Stockholm, Sweden..
    Caidahl, Kenneth
    Karolinska Inst, Dept Mol Med & Surg, Ctr Mol Med, S-17176 Stockholm, Sweden.;Univ Gothenburg, Sahlgrenska Acad, Inst Med, Dept Mol & Clin Med, S-41345 Gothenburg, Sweden..
    Molecular Imaging of a New Multimodal Microbubble for Adhesion Molecule Targeting2019In: Cellular and Molecular Bioengineering, ISSN 1865-5025, E-ISSN 1865-5033, Vol. 12, no 1, p. 15-32Article in journal (Refereed)
    Abstract [en]

    Introduction: Inflammation is an important risk-associated component of many diseases and can be diagnosed by molecular imaging of specific molecules. The aim of this study was to evaluate the possibility of targeting adhesion molecules on inflammation-activated endothelial cells and macrophages using an innovative multimodal polyvinyl alcohol-based microbubble (MB) contrast agent developed for diagnostic use in ultrasound, magnetic resonance, and nuclear imaging. Methods: We assessed the binding efficiency of antibody-conjugated multimodal contrast to inflamed murine or human endothelial cells (ECs), and to peritoneal macrophages isolated from rats with peritonitis, utilizing the fluorescence characteristics of the MBs. Single-photon emission tomography (SPECT) was used to illustrate 99m Tc-labeled MB targeting and distribution in an experimental in vivo model of inflammation. Results: Flow cytometry and confocal microscopy showed that binding of antibody-targeted MBs to the adhesion molecules ICAM-1, VCAM-1, or E-selectin, expressed on cytokine-stimulated ECs, was up to sixfold higher for human and 12-fold higher for mouse ECs, compared with that of non-targeted MBs. Under flow conditions, both VCAM-1- and E-selectin-targeted MBs adhered more firmly to stimulated human ECs than to untreated cells, while VCAM-1-targeted MBs adhered best to stimulated murine ECs. SPECT imaging showed an approximate doubling of signal intensity from the abdomen of rats with peritonitis, compared with healthy controls, after injection of anti-ICAM-1-MBs. Conclusions: This novel multilayer contrast agent can specifically target adhesion molecules expressed as a result of inflammatory stimuli in vitro, and has potential for use in disease-specific multimodal diagnostics in vivo using antibodies against targets of interest.

  • 2802. Ahmed, Niaz
    et al.
    Näsman, Per
    KTH, Superseded Departments, Infrastructure.
    Wahlgren, Nils Gunnar
    Effect of intravenous nimodipine on blood pressure and outcome after acute stroke2000In: Stroke, ISSN 0039-2499, E-ISSN 1524-4628, Vol. 31, no 6, p. 1250-1255Article in journal (Refereed)
    Abstract [en]

    Background and Purpose-The Intravenous Nimodipine West European Stroke Trial (INWEST) found a correlation between nimodipine-induced reduction in blood pressure (BP) and an unfavorable outcome in acute stroke. We sought to confirm this correlation with and without adjustment for prognostic variables and to investigate outcome in subgroups with increasing levels of BP reduction. Methods-Patients with a clinical diagnosis of ischemic stroke (within 24 hours) were consecutively allocated to receive placebo (n=100), 1 mg/h (low-dose) nimodipine (n=101), or 2 mg/h (high-dose) nimodipine (n=94). The correlation between average BP change during the first 2 days and the outcome at day 21 was analysed. Results-Two hundred sixty-five patients were included in this analysis (n=92, 93, and 80 for placebo, low dose, and high dose. respectively). Nimodipine treatment resulted in a statistically significant reduction in systolic BP (SBP) and diastolic BP (DBP) from baseline compared with placebo during the first few days. In multivariate analysis, a significant correlation between DBP reduction and worsening of the neurological score was round for the high-close group (beta=0.49, P=0.048). Patients with a DBP reduction of greater than or equal to 20% in the high-dose group had a significantly increased adjusted OR for the compound outcome variable death or dependency (Barthel Index <60) (n/N=25/26, OR 10.16, 95% CI 1.02 to 101.74) and death alone (n/N=9/26, OR 4.3361 95% CI 1.131 16.619) compared with all placebo patients (n/N=62/92 and 14/92. respectively). There was no correlation between SEP change and outcome. Conclusions-DBP, but not SEP, reduction was associated with neurological worsening after the intravenous administration of high-dose nimodipine after acute stroke. For low-dose nimodipine, the results were not conclusive. These results do not confirm or exclude a neuroprotective property of nimodipine.

  • 2803.
    Ahmed, Noman
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Efficient Modeling of Modular Multilevel Converters for HVDC Transmission Systems2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The drive towards getting more and more electrical energy from renewable sources, requires more efficient electric transmission systems. A stronger grid, with more controllability and higher capacity, that can handle power fluctuations due to a mismatch between generation and load is also needed. High-voltage dc (HVDC) provides efficient and economical power transmission over very long distances, and will be a key player in shaping-up the future electric grid. Due to its outstanding features, the modular multilevel converter (MMC) has already been widely accepted as a key converter topology in voltage-source converter (VSC)-based HVDC transmission systems.

    In order to study the feasibility of future MMC-based HVDC grids, adequate simulation models are necessary. The main objective of the thesis is to propose MMC reduced-order simulation models capable of accurately replicating the response of an MMC during all relevant operating conditions. Such models are the basic building blocks in developing efficient simulation models for HVDC grids. This thesis presents two MMC equivalent simulation models, the continuous model (CM) and the detailed equivalent model (DEM). Compared to the CM, the DEM is also capable of demonstrating the individual sumodule behavior of an MMC. These models are validated by comparing with the detailed MMC model as well as with experimental results obtained from an MMC prototype in the laboratory. The most significant feature of the models is the representation of the blocking capability of the MMC, presented for the first time in the literature for an MMC equivalent simulation model. This feature is very important in replicating the accurate transient behavior of an MMC during energization and fault conditions. This thesis also investigates the performance of the MMC with redundant submodules in the arms. Two different control strategies are used and compared for integrating redundant submodules.

    The proposed MMC models are used in developing point-to-point and multiterminal HVDC (MTDC) systems. A reduced-order model of a hybrid HVDC breaker is also developed and employed in the MTDC system, making the test system capable of accurately replicating the behavior of the MMCbased MTDC system employing hybrid HVDC breakers. The conclusion of the analysis of dc-side faults in a MTDC system is that fast-acting HVDC breakers are necessary to isolate only the faulted part in the MTDC system to ensure the power flow in rest of the system is not interrupted.

    A generic four-terminal HVDC grid test system using the CM model is also developed. The simulated system can serve as a standard HVDC grid test system. It is well-suited to electromagnetic transient (EMT) studies in a limited version of commercially available EMT-type software. The dynamic performance of the HVDC grid is studied under different fault conditions.

  • 2804.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Haider, Arif
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Van Hertem, Dirk
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Zhang, Lidong
    ABB Power Systems, Ludvika.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Prospects and challenges of future HVDC SuperGrids with modular multilevel converters2011In: Proceedings of the 2011-14th European Conference on Power Electronics and Applications (EPE 2011) / [ed] EPE Association, 2011Conference paper (Refereed)
    Abstract [en]

    In order to transmit massive amounts of power generated by remotely located power plants, especially offshore wind farms, and to balance the intermittent nature of renewable energy sources, the need for a stronger high voltage transmission grid is anticipated. Due to limitations in AC power transmission the most likable choice for such a grid is a high voltage DC (HVDC) grid. However, the concept of the HVDC grid is still under active development as different technical challenges exist, and it is not yet possible to construct such a DC grid. This paper deals with prospects and technical challenges for the future HVDC SuperGrids. Different topologies for a SuperGrid and the possibility to use modular multilevel converters (M2Cs) are presented. A comprehensive overview of different sub-module implementations of M2C is given. An overview of short circuit behaviour of the M2C is also given, as well as a discussion on the choice between cables or overhead lines and DC-side resonance issues.

  • 2805.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Haider, Arif
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Ängquist, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    M2C-BASED MTDC SYSTEM FOR HANDLING OF POWERFLUCTUATIONS FROM OFFSHORE WIND FARMS2011In: Proceedings of IET RPG-2011 / [ed] IET, 2011Conference paper (Refereed)
    Abstract [en]

    In this paper a modular multilevel converter (M2C) basedmulti-terminal direct current (MTDC) system is proposed forthe connection of offshore wind farms. Each M2C ismodelled with 36 sub-modules per arm with a total of 216sub-modules consisting of half bridges. An open-loopconverter control method is employed for the M2Cs. Powersynchronizationcontrol is used instead of a phase-locked loop(PLL) for synchronization. A voltage controller isimplemented with power-synchronization control as an innerloop. By means of numerical simulations in PSCAD, it isshown that the system is self stabilizing both at steady stateand following power fluctuations of the wind farm.

  • 2806.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Haider, Arif
    Van Hertem, Dirk
    ESAT/ELECTA, K.U.Leuven, Belgium.
    Zhang, Lidong
    ABB Power Systems HVDC, Ludvika.
    Harnefors, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    HVDC SuperGrids with modular multilevel converters - The power transmission backbone of the future2012In: International Multi-Conference on Systems, Signals and Devices, SSD 2012, IEEE , 2012, p. 6198119-Conference paper (Refereed)
    Abstract [en]

    In order to transmit massive amounts of power generated by remotely located power plants, especially offshore wind farms, and to balance the intermittent nature of renewable energy sources, the need for a stronger high voltage transmission grid is anticipated. Due to limitations in ac power transmission the most likable choice for such a grid is a high-voltage dc (HVDC) grid. However, the concept of the HVDC grid is still under active development as different technical challenges exist, and it is not yet possible to construct such a dc grid. This paper deals with prospects and technical challenges for future HVDC SuperGrids. Different topologies for a SuperGrid and the possibility to use modular multilevel converters (M2Cs) are presented. A comprehensive overview of different submodule implementations of M2C is given as well as a discussion on the choice between cables or overhead lines, the protection system for the dc grid and dc-side resonance issues.

  • 2807.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Ängquist, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Antonopoulos, Antonios
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion. ABB Corporate Research.
    Harnefors, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Performance of the modular multilevel converter with redundant submodules2015In: IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society, Institute of Electrical and Electronics Engineers (IEEE), 2015, p. 3922-3927, article id 7392712Conference paper (Refereed)
    Abstract [en]

    The modular multilevel converter (MMC) is the state-of-the-art voltage-source converter (VSC) topology used for various power-conversion applications. In the MMC, submodule failures can occur due to various reasons. Therefore, additional submodules called the redundant submodules are included in the arms of the MMC to fulfill the fault-safe operation requirement. The performance of the MMC with redundant submodules has not been widely covered in the published literature. This paper investigates the performance of the MMC with redundant submodules in the arms. Two different control strategies are used and compared for integrating redundant submodules. The response of the MMC to a submodule failure for the two strategies is also studied. Moreover, the operation of the MMC with redundant submodules is validated experimentally using the converter prototype in the laboratory.

  • 2808.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Ängquist, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Mahmood, Shahid
    Antonopoulos, Antonios
    Harnefors, Lennart
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Efficient Modeling of an MMC-Based Multiterminal DC System Employing Hybrid HVDC Breakers2015In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 30, no 4, p. 1792-1801Article in journal (Refereed)
    Abstract [en]

    The feasibility of future multiterminal dc (MTDC) systems depends largely on the capability to withstand dc-side faults. Simulation models of MTDC systems play a very important role in investigating these faults. For such studies, the test system needs to be accurate and computationally efficient. This paper proposes a detailed equivalent model of the modular multilevel converter (MMC), which is used to develop the MTDC test system. The proposed model is capable of representing the blocked-mode operation of the MMC, and can be used to study the balancing control of the capacitor voltages. In addition, the operation of the MMC when redundant submodules are included in the arms can also be studied. A simplified model of a hybrid high-voltage dc breaker is also developed. Hence, the developed test system is capable of accurately describing the behavior of the MMC-based MTDC system employing hybrid HVDC breakers, during fault conditions. Using time-domain simulations, permanent dc-side faults are studied in the MTDC system. In addition, a scheme to control the fault current through the MMC using thyristors on the ac side of the converter is proposed.

  • 2809.
    Ahmed, Noman
    et al.
    KTH.
    Ängquist, Lennart
    KTH.
    Mehmood, Shahid
    Antonopoulos, Antonios
    Harnefors, Lennart
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Efficient Modeling of an MMC-Based Multiterminal DC System Employing Hybrid HVDC Breakers2016In: 2016 IEEE POWER AND ENERGY SOCIETY GENERAL MEETING (PESGM), IEEE , 2016Conference paper (Refereed)
  • 2810.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Ängquist, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Continuous modeling of open-loop control based negative sequence current control of modular multilevel converters for HVDC transmission2013In: Eur. Conf. Power Electron. Appl., EPE, 2013Conference paper (Refereed)
    Abstract [en]

    Negative sequence currents are obtained during ac-side asymmetrical faults of converters in highvoltage direct current (HVDC) transmission systems. Consequently, second order harmonics in the dc-side voltage and current, unbalanced ac-side currents, and power oscillations can be observed. This paper presents a negative sequence current control (NSCC) scheme that eliminates second order harmonic ripples in the voltage and current of the dc-side during unbalanced grid conditions. Controllers for this purpose are investigated using a continuous model of the modular multilevel converter (M2C). The proposed scheme utilizes an open-loop controller for lower level control of the M2C. The continuous model used also has the capability to model blocking and deblocking events which may be used during protective actions. Simulation results reveal that the proposed NSCC scheme is effective in suppressing dc-side voltage and current ripples. Moreover, it keeps the ac-side phase currents balanced during asymmetrical fault conditions.

  • 2811.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Ängquist, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Antonopoulos, Antonios
    ABB Corporate Research Center, Sweden.
    Harnefors, Lennart
    ABB Corporate Research Center, Sweden.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    A computationally efficient continuous model for the modular multilevel converter2014In: IEEE Journal of Emerging and Selected Topics in Power Electronics, ISSN 2168-6777, Vol. 2, no 4, p. 1139-1148, article id 6840290Article in journal (Refereed)
    Abstract [en]

    Simulation models of the modular multilevel converter (MMC) play a very important role for studying the dynamic performance. Detailed modeling of the MMC in electromagnetic transient simulation programs is cumbersome, as it requires high computational effort and simulation time. Several averaged or continuous models proposed in the literature lack the capability to describe the blocked state. This paper presents a continuous model, which is capable of accurately simulating the blocked state. This feature is very important for accurate simulation of faults. The model is generally applicable, although it is particularly useful in high-voltage dc applications.

  • 2812.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Ängquist, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Efficient Modeling of Modular Multilevel Converters in HVDC-Grids Under Fault Conditions2014In: 2014 IEEE PES General Meeting | Conference & Exposition, IEEE Computer Society, 2014, p. 6939166-, article id 6939166Conference paper (Refereed)
    Abstract [en]

    High-voltage direct current (HVDC) grids using modular multilevel converters (M2Cs) have strongly been considered for the integration of distant renewable energy sources and also as a backbone to the existing ac-grids. The dynamic performance of the M2C is of particular interest in these grids. For electromagnetic transient (EMT) programs, modeling of HVDC-grids using detailed M2C models is unrealistic, as it requires extremely high computational effort and simulation time. In this paper an HVDC-grid test system is developed using a continuous simulation model of the M2C. The model is also capable of describing the blocking events of the M2C. Using time-domain simulations in PSCAD/EMTDC, the dynamic performance of the M2C in HVDC-grids under fault conditions is investigated. Simulation results reveal that the continuous M2C model can efficiently be used to study the dynamic performance of the M2C in HVDC-grids with high computational speed, under different fault conditions.

  • 2813.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Ängquist, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Validation of the continuous model of the modular multilevel converter with blocking/deblocking capability2012In: AC and DC Power Transmission (ACDC 2012), 10th IET International Conference on, 2012Conference paper (Refereed)
    Abstract [en]

    This paper presents the continuous model for the Modular Multilevel Converter (M2C). The model operates in two modes, either operating as a voltage source in deblocked mode or as a rectifying diode bridge in blocked mode. The model is validated by comparison with a detailed M2C model having 36 submodules per arm, using different control strategies. The comparison is based on time-domain simulations in PSCAD/EMTDC. The continuous model shows a very good agreement with the detailed model.

  • 2814.
    Ahmed, Olfet
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Saman, Nawar
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Utvärdering av nätverkssäkerheten på J Bil AB2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this project is to evaluate the network security at J Bil AB. The focus will be on both social and technical issues. For the employees to be able to con-nect to remote servers and external services and perform their daily work tasks, secure connections is needed. J Bil Ab has no IT manager who actively maintains and monitors the network; rather they consult a computer company when changes and implementations are required. The projects’ goal is to identify gaps, come up with suggestions for improvement and to some extent implement so-lutions. To do this, an observation of the employees hav been made, an inter-view have been held, and several attacks on the network have been performed. Based on the data collected, it was concluded that the company has shortcom-ings in IT security. Above all, the social security appeared to have major gaps in it and that is mainly because the lack of knowledge among the employees and they have never been informed of how to manage their passwords, computers and IT issues in general. Suggestions for improvement have been given and some implementations have been performed to eliminate the deficiencies.

  • 2815. Ahmed, Omar Jamil
    et al.
    McFarland, James
    Kumar, Arvind
    Brown University, United States.
    Reactivation in ventral striatum during hippocampal ripples: evidence for the binding of reward and spatial memories?2008In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 28, no 40, p. 9895-9897Article in journal (Refereed)
  • 2816.
    Ahmed, Rakiv
    et al.
    KTH, School of Computer Science and Communication (CSC).
    Aule, Jonas
    KTH, School of Computer Science and Communication (CSC).
    An Evaluation of the Framework Libgdx when Developing a Game Prototype for Android Devices.2011Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    An evaluation of the framework Libgdx

    when developing a game prototype for Android devices

    By: Rakiv Ahmed & Jonas Aule

    ABSTRACT

    This paper is about evaluation of the framework Libgdx, regarding 2D game development for the Android platform. Other frameworks are also investigated briefly. The game under development is an original game called Magnificent Marbles and is multi-modal as other games for smartphones. The Background section talks about the Android platform and its related tools along with game examples, also frameworks are introduced here. The main focus of this paper will be on the Implementation section and the actual usage of Libgdx. Methods and results for different development versions of the game will be displayed.

    The Discussion section concludes that Libgdx is a good framework due to its desktop support. Libgdx may not suitable for smaller game projects or when wanting to get started quickly without too much knowledge in other areas, such as OpenGL. Another issue is that one should not solely rely on Libgdx desktop support, but knowledge in other areas is required as well to utilize Libgdx to the fullest. The Appendix section includes different documents for more information about Magnificent Marbles.

  • 2817.
    Ahmed, Sabih Zeb
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Reduction of vibrations during horizontal milling of aluminum parts: An Experimental and Numerical Study 2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis aims at vibration problem during milling operation. Vibration sets in at tool- workpiece interface if certain conditions are achieved. Research has been carried out try to reduce or eliminate chatter. Chatter decreases the dimensional accuracy and surface finish of workpiece.

    Main objective is to examine the source of vibration and provide as solution to problem based on the findings. CAD Model of workpiece and clamping has been developed as close to real system as possible. Experimental modal analysis and Finite Element analysis is done to obtain system behaviour during vibration. Natural frequencies are determined and then compared with possible sources of excitation.

    Modal testing and computer simulations are done before and after Final cutting operations to map out complete behaviour of system. Both forced excitation and self-excited vibrations are taken in consideration during measurements. Finally calculations are done to determine the solution and give recommendations. Suggestions for future work in this area are also provided that could enable SAAB to analyse and improve machining of all parts.

  • 2818.
    Ahmed, Salahuddin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Transformation and Expectations: From Landowner’s and Developer’s Perspective: A case study of Dhanmondi R/A2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 2819.
    Ahmed, Samih
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Minchot, Guayente
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Post-tensioned stress ribbon systems in long-span roofs: Case study: Västerås Travel Center2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The stress ribbon system has numerous advantages, that includes but are not limitedto: increasing overall stiffness, control deflections and reduction of materialsconsumption, which in turn, reduces the load and the cost. Nevertheless, its use isusually limited to bridges, in particular, pedestrian bridges; this can be attributedto the insufficient space that buildings’ usually have for end supports, or/and backstayedcables, that can accommodate the expected high pull-out forces occuring atthe cables’ ends.

    In this work, the roof of Västerås Travel Center, which will become one of the longestcable suspended roofs in the world, was chosen as a case study. The aim was toinvestigate the optimal technique to model the post-tensioned stress ribbon systemfor the roof structure using SAP2000, and to assess any possible reduction in thepull-out forces, deflections and concrete stresses. Subsequently, a conventional cablesuspended roof was simulated, using SAP2000, and compared to the post-tensionstress ribbon system in order to examine the potential of the latter. Moreover,the effects of temperature loads and support movements on the final design loadswere examined. Based on the study, a few practical recommendations concerningthe construction method and the iterative design process, required to meet thearchitectural geometrical demands, are stated by the authors.

    The results showed that the post-tensioned stress ribbon system reduces the concretestresses, overall deflections, and more importantly, reduces the pull-out forces by upto 16%, which substantially reduces the design forces for the support structures.The magnitude of these reductions was found to be highly correlated to the appliedprestressing force, making the size of the prestressing force a key factor in the design.

  • 2820.
    Ahmed, Samy
    et al.
    KTH, School of Electrical Engineering (EES).
    Björk, Joel
    KTH, School of Electrical Engineering (EES).
    Autonomous Alignment Between a Single Mode Optical Fiber and a Grating Coupler2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 2821.
    Ahmed, Shadman
    et al.
    KTH, School of Engineering Sciences (SCI).
    Ugur, Oguzhan
    KTH, School of Engineering Sciences (SCI).
    PID in Smart Buildings2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This paper investigates a smart heat control system inside a household using a family of dynamic controllers called PID (Proportional Integrative Derivative), conducted with Wireless Sensor Networks (WSN). The laws of thermodynamics and other physical knowledge was used to model the effect that a heat exchanger has on the temperature of a room. Realistic simulations have been run to illustrate how a PID control system outperforms the traditional on-off approach, in terms of energy efficiency. Simulations shows that the PID controlled system is 28% more energy efficient than an on-off. This can make the future use of PIDs in home automation more common. Lastly a future extension to other systems is discussed.

  • 2822.
    Ahmed, Shadman
    et al.
    KTH, School of Engineering Sciences (SCI).
    Ugur, Oguzhan
    KTH, School of Engineering Sciences (SCI).
    PID in Smart Buildings2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This paper investigates a smart heat control systeminside a household using a family of dynamic controllers calledPID (Proportional Integrative Derivative), conducted withWireless Sensor Networks (WSN). The laws of thermodynamicsand other physical knowledge was used to model the effect that aheat exchanger has on the temperature of a room. Realisticsimulations have been run to illustrate how a PID control systemoutperforms the traditional on-off approach, in terms of energyefficiency. Simulations shows that the PID controlled system is28% more energy efficient than an on-off. This can make thefuture use of PIDs in home automation more common. Lastly afuture extension to other systems is discussed.

  • 2823.
    Ahmed, Shoaib
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Topology optimization of load-carryingstructures using three different typesof finite elements2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis deals with topology optimization of load-carrying structures, in particular compliance minimization subject to a constraint on the total amount of material to be used. The main purpose of the work was to compare the following three types of finite elements for the above topology optimization problems: Four node square elements with bilinear shape functions, nine node square elements with quadratic shape functions, and six node hexagonal elements with Wachspress shape functions. The SIMP approach (Solid Isotropic Material with Penalization) was used to model the topology optimization problem for different load and support conditions, and the method of moving asymptotes (MMA) was used to solve the formulated optimization problems. On the considered test problems, it turned out that the results obtained by using six node hexagonal elements were in general better than the corresponding results using nine node square elements which in turn were better than the results using four node square elements. The price paid for the improvements were increased computation times.

  • 2824. Ahmed, S.N
    et al.
    Strandberg, Jonas
    Stockholms universitet.
    Zverev, E.G.
    et al.,
    The D0 Silicon Microstrip Tracker2011In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 634, no 1, p. 8-46Article in journal (Refereed)
    Abstract [en]

    This paper describes the mechanical design, the readout chain, the production, testing and the installation of the Silicon Microstrip Tracker of the D0 experiment at the Fermilab Tevatron collider. In addition, we describe the performance and operational experience of the detector during the experiment data collection between 2001 and 2010.

  • 2825.
    Ahmed, Sunny
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Olsson, Linnéa
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Urbanears Ugglan - Studying Usercentered Designin Product Development2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report describes the master’s thesis conducted by Sunny Ahmed and Linnéa Olssonat KTH Royal Institute of Technology for the client Zound Industries. By exploringemerging technologies and user needs, the project members developed a design proposal forheadphones for active users that can be released in three to five years’ time.Urbanears Ugglan is the headphone solution that allows you to take control of your physicalactivities and experience true freedom. It consists of two parts: true wireless earphonesand a wearable wrist accessory that stores and charges the earphones on the go, while alsofunctioning as a fitness tracker.Aside from the first purpose of creating the design proposal, the second purpose of the thesiswas to investigate the impact of involving the intended user in the design process duringproduct development when adopting a user-centered design approach.Different methods were used to gather relevant information. Both market research and atechnical trend analysis were done as background research, and complemented the userstudies. The insights discovered from these phases were used to generate concepts, fromwhich one was selected for further development after discussion with the client company. Thisconcept evolved into the final design proposal, Urbanears Ugglan.The project team found a positive impact from using user-centered design and involving theuser in several stages of the project. Including the intended user in the development led toa better understanding of their needs and values, which in turn allowed the project team toquickly verify the potential of product ideas.

  • 2826. Ahmed, T.
    et al.
    Albers, R. C.
    Balatsky, Alexander V.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Friedrich, C.
    Zhu, J. -X
    G W quasiparticle calculations with spin-orbit coupling for the light actinides2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 3, p. 035104-Article in journal (Refereed)
    Abstract [en]

    We report on the importance of GW self-energy corrections for the electronic structure of light actinides in the weak-to-intermediate coupling regime. Our study is based on calculations of the band structure and total density of states of Np, U, and Pu using a one-shot GW approximation that includes spin-orbit coupling within a full potential LAPW framework. We also present RPA screened effective Coulomb interactions for the f-electron orbitals for different lattice constants, and show that there is an increased contribution from electron-electron correlation in these systems for expanded lattices. We find a significant amount of electronic correlation in these highly localized electronic systems.

  • 2827.
    Ahmed, Tanvir Saif
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Markovic, Bratislav
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Distribuerade datalagringssystem för tjänsteleverantörer: Undersökning av olika användningsfall för distribuerade datalagringssystem2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis, a study of three different uses cases has been made within the field of data storage, which are as following: Cold Storage, High Performance Storage and Virtual Machine Storage. The purpose of the survey is to give an overview of commercial distributed file systems and a deeper study of open source codes distributed file systems in order to find the most optimal solution for these use cases. Within the study, previous works concerning performance, data protection and costs were an-alyzed and compared in means to find different functionalities (snapshotting, multi-tenancy, data duplication and data replication) which distinguish modern distributed file systems. Both commercial and open distributed file systems were examined. A cost estimation for commercial and open distrib-uted file systems were made in means to find out the profitability for these two types of distributed file systems.After comparing and analyzing previous works, it was clear that the open source distributed file sys-tem Ceph was proper as a solution in accordance to the objectives that were set for High Performance Storage and Virtual Machine Storage. The cost estimation showed that it was more profitable to im-plement an open distributed file system. This study can be used as guidance to choose between different distributed file systems.

  • 2828. Ahmed, Towfiq
    et al.
    Haraldsen, Jason T.
    Rehr, John J.
    Di Ventra, Massimiliano
    Schuller, Ivan
    Balatsky, Alexander V.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Correlation dynamics and enhanced signals for the identification of serial biomolecules and DNA bases2014In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 25, no 12, p. 125705-Article in journal (Refereed)
    Abstract [en]

    Nanopore-based sequencing has demonstrated a significant potential for the development of fast, accurate, and cost-efficient fingerprinting techniques for next generation molecular detection and sequencing. We propose a specific multilayered graphene-based nanopore device architecture for the recognition of single biomolecules. Molecular detection and analysis can be accomplished through the detection of transverse currents as the molecule or DNA base translocates through the nanopore. To increase the overall signal-to-noise ratio and the accuracy, we implement a new 'multi-point cross-correlation' technique for identification of DNA bases or other molecules on the single molecular level. We demonstrate that the cross-correlations between each nanopore will greatly enhance the transverse current signal for each molecule. We implement first-principles transport calculations for DNA bases surveyed across a multilayered graphene nanopore system to illustrate the advantages of the proposed geometry. A time-series analysis of the cross-correlation functions illustrates the potential of this method for enhancing the signal-to-noise ratio. This work constitutes a significant step forward in facilitating fingerprinting of single biomolecules using solid state technology.

  • 2829. Ahmed, Towfiq
    et al.
    Haraldsen, Jason T.
    Zhu, Jian-Xin
    Balatsky, Alexander V.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Institute for Materials Science, Los Alamos National Laboratory, United States.
    Next-Generation Epigenetic Detection Technique: Identifying Methylated Cytosine Using Graphene Nanopore2014In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 5, no 15, p. 2601-2607Article in journal (Refereed)
    Abstract [en]

    DNA methylation plays a pivotal role in the genetic evolution of both embryonic and adult cells. For adult somatic cells, the location and dynamics of methylation have been very precisely pinned down with the 5-cytosine markers on cytosine-phosphate-guanine (CpG) units. Unusual methylation on CpG islands is identified as one of the prime causes for silencing the tumor suppressant genes. Early detection of methylation changes can diagnose the potentially harmful oncogenic evolution of cells and provide promising guideline for cancer prevention. With this motivation, we propose a cytosine methylation detection technique. Our hypothesis is that electronic signatures of DNA acquired as a molecule translocates through a nanopore would be significantly different for methylated and nonmethylated bases. This difference in electronic fingerprints would allow for reliable real-time differentiation of methylated DNA. We calculate transport currents through a punctured graphene membrane while the cytosine and methylated cytosine translocate through the nanopore. We also calculate the transport properties for uracil and cyanocytosine for comparison. Our calculations of transmission, current, and tunneling conductance show distinct signatures in their spectrum for each molecular type. Thus, in this work, we provide a theoretical analysis that points to a viability of our hypothesis.

  • 2830.
    Ahmed, Waqas
    KTH, School of Information and Communication Technology (ICT).
    Implementation and Verification of a CPU Subsystem for Multimode RF Transceivers2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Multimode transceivers are becoming a very popular implementation alternative because of their ability to support several standards on a single platform. For multimode transceivers, advanced control architectures are required to provide flexibility, reusability, and multi-standard support at low power consumption and small die area effort. In such an advance control architecture the CPU Subsystem functions as a central control unit which configures the transceiver and the interface for a particular communication standard.

    Open source components are gaining popularity in the market because they not only reduce the design costs significantly but also provide power to the designer due to the availability of the full source code. However, open source architectures are usually available as poorly verified and untested intellectual properties (IPs). Before they can be commercially adapted, an extensive testing and verification strategy is required. In this thesis we have implemented a CPU Subsystem using open source components and performed the functional verification of this Subsystem. The main components of this CPU Subsystem are (i) an open source OpenRISC1200 core, (ii) a memory system, (iii) a triple-layer Sub-bus system and (iv) several Wishbone interfaces. The OpenRISC1200 core was used because it is a 32-bit core ideally suited for applications requiring high performance while having low-cost and low power consumption. The verification of a 5-stage pipeline processor is a challenging task and to the best of our knowledge this is the first attempt to verify the Open-RISC1200 core. The faults identified as a result of the functional verification will not only prove useful for the current project but will likelymake the OpenRISC1200 core a more reliable and commercially used processor.

  • 2831.
    Ahmed, War
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Bahador, Mehrdad
    KTH, School of Electrical Engineering and Computer Science (EECS).
    The accuracy of the LSTM model for predicting the S&P 500 index and the difference between prediction and backtesting2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this paper the question of the accuracy of the LSTM algorithm for predicting stock prices is being researched. The LSTM algorithm is a form of deep learning algorithm. The algorithm takes in a set of data as inputs and finds a pattern to dissolve an output. Our results point to that using backtesting as the sole method to verify the accuracy of a model can fallible. For the future, researchers should take a fresh approach by using real-time testing. We completed this by letting the algorithm make predictions on future data. For the accuracy of the model we reached the conclusion that having more parameters improves accuracy.

  • 2832.
    Ahmed, Yahye
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje).
    Carlsson, Ossian
    KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje).
    Analys: Olyckor och tillbud vid pappersmassabruk2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 2833. Ahmed, Zakir
    et al.
    Bhardwaj, Krishna
    Krishnan, Ramesh
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Estimation of Sample Clock Frequency Offset Using Error Vector Magnitude2011Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A low complexity system and method for operating a receiver in order to estimate an offset between the actual sample clock rate 1/TS' of a receiver and an intended sample clock rate 1/TS. The receiver captures samples of a received baseband signal at the rate 1/TS', operates on the captured samples to generate an estimate for the clock rate offset, and fractionally resamples the captured samples using the clock rate offset. The resampled data represents an estimate of baseband symbols transmitted by the transmitter. The action of operating on the captured samples involves computing an error vector signal and then estimating the clock rate offset using the error vector signal. The error vector signal may be computed in different ways depending on whether or not carrier frequency offset and carrier phase offset are assumed to be present in the received baseband signal.

  • 2834. Ahmed, Zakir
    et al.
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Blind mechanism for the joint estimation of frequency offset and phase offset for QAM modulated signals2010Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A mechanism for jointly correcting carrier phase and carrier frequency errors in a demodulated signal. A computer system may receive samples of a baseband input signal (resulting from QAM demodulation). The computer system may compute values of a cost function J over a grid in a 2D angle-frequency space. A cost function value J(theta,omega) is computed for each point (theta,omega) in the grid by (a) applying a phase adjustment of angle theta and a frequency adjustment of frequency omega to the input signal; (b) performing one or more iterations of the K-means algorithm on the samples of the adjusted signal; (c) generated a sum on each K-means cluster; and (d) adding the sums. The point (thetae,omegae) in the 2D angle-frequency space that minimizes the cost function J serves an estimate for the carrier phase error and carrier frequency error.; The estimated errors may be used to correct the input signal.

  • 2835. Ahmed, Zakir
    et al.
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Maximizing the Viterbi Winning Path Metric to Estimate Carrier Frequency and Phase Offsets in Continuous Phase Modulated Signals2012Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A system and method for estimating carrier frequency offset Δf and carrier phase offset φ0 inherent in a received CPM signal. Samples of a continuous phase modulated (CPM) signal are received. A maximum of an objective function J is determined over a two-dimensional region parameterized by frequency offset v and phase offset w. The coordinates vmax and wmax of a maximizing point in the region represent estimates of the carrier frequency offset Δf and the carrier phase offset φ0. To evaluate the objective function J at a point (v, w), apply a frequency shift of amount −v and a phase shift of amount −w to the received samples to obtain modified samples, and perform Viterbi demodulation on the modified samples to obtain a winning path metric value at a final time. The winning path metric value is the objective function value J(v, w). 

  • 2836.
    Ahmed, Zakir
    et al.
    Motorola India Electron. Ltd., Bangalore .
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Sancheti, Nirmal Kumar
    A time domain based efficient block decision algorithm for audio coders2007In: International Symposium on Communications and Information Technologies, 2007. ISCIT '07, IEEE Press, 2007, p. 1077-1081Conference paper (Refereed)
    Abstract [en]

    In typical audio encoders the block decision is done either using time-domain techniques like energy computation or frequency domain techniques like temporal noise shaping (TNS) [1], [2]. The time-domain energy computation based decisions are less effective for detecting many of the stringent scenarios presented by test cases like castanets and fatboy. The frequency domain based algorithms have better decision making capabilities, however they are inherently complex as they require the computation of the FFT, additionally in case of TNS the computation of LPC (Linear Prediction coding) in the frequency domain. An improved time-domain technique with better block decision capability compared to TNS and with lesser computational complexity is proposed in this paper.

  • 2837. Ahmed, Zara
    et al.
    Benque, David
    Berezin, Sergey
    Dahl, Anna Caroline E.
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Fisher, Jasmin
    Hall, Benjamin A.
    Ishtiaq, Samin
    Nanavati, Jay
    Piterman, Nir
    Riechert, Maik
    Skoblov, Nikita
    Bringing LTL Model Checking to Biologists2017In: VMCAI 2017: Verification, Model Checking, and Abstract Interpretation / [ed] Bouajjani, A Monniaux, D, Springer, 2017, Vol. 10145, p. 1-13Conference paper (Refereed)
    Abstract [en]

    The BioModelAnalyzer (BMA) is a web based tool for the development of discrete models of biological systems. Through a graphical user interface, it allows rapid development of complex models of gene and protein interaction networks and stability analysis without requiring users to be proficient computer programmers. Whilst stability is a useful specification for testing many systems, testing temporal specifications in BMA presently requires the user to perform simulations. Here we describe the LTL module, which includes a graphical and natural language interfaces to testing LTL queries. The graphical interface allows for graphical construction of the queries and presents results visually in keeping with the current style of BMA. The Natural language interface complements the graphical interface by allowing a gentler introduction to formal logic and exposing educational resources.

  • 2838.
    Ahmed, Zeeshan
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Analysis of Partial Discharge in OIP Bushing Models2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A high voltage bushing is a very important accessory of power transformers. Bushings are used to insulate high voltage conductors where they feed through steel tank of a power transformer. There are different sources of electric stress that may result in degradation of bushing. Partial discharges (PDs) are one of the main sources of electrical degradation. PDs occur due to defects in electrical insulations, and can lead to insulation failure. This thesis is composed of two parts. The first part deals with design of a 145 kV oil impregnated paper (OIP) bushing by using capacitive radial grading technique. In capacitive grading the foils of calculated length are placed at predetermined radial distance between the paper layers in order to distribute voltage and electric field uniformly between high voltage conductor and ground potential. A 145kV OIP bushing was designed according to dimensions of ABB GOE type bushing. After calculations, the 145 kV bushing geometry was modeled in COMSOL Multiphysics in order to analyze the voltage and electric field distribution in the bushing. In the second part of this thesis a scaled down model was designed using the capacitive radial grading technique. After designing, the scale down model was implemented in COMSOL in order to ensure that the voltage and electric field distribution should be similar to the full scale model of bushing. The scaled down bushing test model was made in laboratory by wrapping impregnated papers and foils on conductor tube according to calculated dimensions. These papers were impregnated with mineral oil. The test model was placed in an oil filled tube. Different defects were added in scale down bushing model and model was connected to PD measurement set up. PD inception voltage was measured and PD patterns were recorded on an insulation condition monitoring system (ICM). These patterns are analyzed in order to conclude about the signature of partial discharges in OIP bushings. From the PD pattern, the type and location of PDs can be concluded. PD patterns reveal that the main causes of PDs in OIP bushing can be gas filled cavities and surface discharges from foil edges.

  • 2839. Ahmed, Zeeshan
    et al.
    Steiner, Ingmar
    Székely, Éva
    CNGL, UCD.
    Carson-Berndsen, Julie
    A system for facial expression-based affective speech translation2013In: Proceedings of the companion publication of the 2013 international conference on Intelligent user interfaces companion, 2013, p. 57-58Conference paper (Refereed)
    Abstract [en]

    In the emerging eld of speech-to-speech translation, empha- sis is currently placed on the linguistic content, while the sig- ni cance of paralinguistic information conveyed by facial ex- pression or tone of voice is typically neglected. We present a prototype system for multimodal speech-to-speech transla- tion that is able to automatically recognize and translate spo- ken utterances from one language into another, with the out- put rendered by a speech synthesis system. The novelty of our system lies in the technique of generating the synthetic speech output in one of several expressive styles that is au- tomatically determined using a camera to analyze the user’s facial expression during speech. 

  • 2840.
    Ahmetasevic, Mia
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Shamoun, Helena
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    The Incorporation of the Tenant into the Public Construction Project: Through the three parameters of communication; Organisational culture, power and trust2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Public construction projects set the standards for new procedures and perspectives within the industry. A way of improving procedures is through communication and the inclusion of all involved parties. It is therefore the purpose of this report to investigate how communication through organisational culture, power and trust can affect the incorporation of the tenant in the construction process. Two case studies, both having public future tenants and public clients, were chosen to enable the investigation of the three parameters of communication, organisational culture, power and trust. The empirics showed that the tenant was often excluded from the construction process due to their differing cultural background. The results also showed that the tenant was considered to have lower status which was exploited at times. In addition, it was found that although opportunistic behaviour was present in the construction project, it was a greater internal issue within the tenant organisation. In the conclusion the authors recommend construction management to evaluate the consequences of incorporating the tenant in the construction meetings as it could lead to less construction errors. They further recommend the public organisations to oversee their distribution of resources in order to avoid opportunistic behaviour.

  • 2841.
    Ahmic, Edvin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Akbarov, Dosmat
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Klassifikationssystemens påverkan på kalkylarbete: En jämförelse mellan CoClass och BSAB-systemen2018Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    As the construction industry shifts to digital information modeling of its projects, the need to coordinate and improve the efficiency of the management of this information increases. A common language in the form of an industry-wide classification system could lead to billions in savings annually. In the calculation, it is important that the correct information management is included in order to provide the most accurate calculation possible.

    The aim of this study is to examine how the three different systems, BSAB 83, BSAB 96 and CoClass, differ and stand in contrast to each other to highlight and demonstrate such differences. The purpose of the study is that it should be used as a basis for how ÅF can create classified calculations with CoClass.

    To achieve the aim of the report and answer the research questions, the examination consisted of literature studies, interviews, a comparative study and a case study. These methods contributed to the following result: ÅF could effectively transfer to the CoClass system. When comparing the systems, it has been shown that CoClass is a more extensive and comprehensive system structured in a different way as opposed to the previous classification systems.

    Based on the results of the study, a calculation structure according to CoClass can be implemented in ÅF's current working methods, where ready-made recipe for building components can still be used. The recommendation is to consider the component table as equivalent to the production result in the calculation work with CoClass structure in the MAP. In the long run, this would have been an efficient strategy, both economically and primarily less time-consuming.

  • 2842.
    Ahmid, Abdel
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    More than downloading: Toward a scale with wireless connectivity2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sensors are light-weight, low powered devices that measure some aspect of a physical or virtual environment and transmit this information in some format. This thesis describes how to integrate a sensor onto devices to enable network connectivity.

    The phrase “internet of things” suggests that within a few years many devices will be connected to an internet. Devices, including common household appliances, will transmit and receive data over a network. The CEO of Ericsson has stated that there will be more than 50 billion connected devices by 2020[1]. These devices could be microwaves, fridges, lights, or temperature sensors. Devices that are usually not associated with internet connectivity will be integrated into networks and play a larger role in providing information and controlling other devices. Sensors will have a major role in “the internet of things”. These small computers could be integrated in any appliances and transmit data over the network. The sensors’ low power and low cost, as well as their light weight, makes them very attractive to integrate them into many devices. The goal of this thesis project is to build upon this trend toward “The internet of things” by integrating a sensor into a bathroom scale thus enabling the scale to have networking connectivity. The sensor will be low cost and simple. It should wirelessly or via USB transmit the current weight that it measures to a receiver (specifically a gateway). This gateway will forward the message over the network to a website or mobile phone for visual presentation of the data. This thesis describes different techniques and approaches toward developing this sensor. The thesis also evaluates these different choices in order to select one technique that will be implemented. This solution will be evaluated in terms of its cost and ease of integration into an existing commercially produced scale.

  • 2843.
    Ahmned, Sragadin
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Reningsmetoder för minskning av oljelukt från bergrummen i Oxelösunds Hamn AB2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This compilation of technology and the costs of limiting emissions of volatile organic substances that have caused oil odor problems with different procedures has been made on behalf of Oxelösund Hamn AB. In Oxelösunds Hamn AB heavy oil and VGOoil is handled. The oil is unloaded from ships to caverns and then re-loaded from the caverns to ships. The port has seven caverns; six of them are in use while the seventh is not.

    The caverns have a common ventilation system for breathing. When the oil is unloaded from the ships to the caverns, the hydrocarbon air volume are corresponding the volume of oil being over-pumped will be squeezed out from the caverns, creating oil odor problems. The oil's odor problem also arises when a change of temperature, i.e. when the temperature rises outside, the oil smell increases and vice versa. There are also other factors influencing the odor problem and these are pressure change, in other words the air circulation in the caverns and the draft. In order to identify what the smell of Oxelösunds Hamn AB consists of an air sampling has been made both in the caverns and outdoors, by the chimney (the caverns common exhaust pipes). Air samples have shown high concentrations of various VOC s 13,000 ppm.

    According to § 8 a For the protection of human health in the Environmental Protection Act may benzene belonging to volatile organic compounds (VOCs) after 1 January 2010 not be present in outdoor air by more than an average of 5 g/m3 air as an annual average. Regulation (2003:112). Emissions of volatile organic compounds in Europe are regulated by the Directive (2001/81/EC), the so-called ceiling directive. Ceiling directive of VOC means that Sweden is committed to reach an emission level of 241 000 tons per year by 2010.

    In this diploma work reports on the different solution techniques are available to reduce oil odor problem. Established methods of emission treatment consist of a catalytic or thermal incineration, adsorption, absorption, condensation and bioremediation techniques. After a technical evaluation of various alternatives incineration and adsorption have been found to be appropriate techniques in this case. To be sure that the selected treatment technology is appropriate for the situaV tion, incineration technology in the form of catalytic combustion is the recommended treatment technology for reduction of oil odor problem and VOC limits. As combustion technologies, there different techniques to choose from such as catalytic- and conventional thermal combustion or incineration in the combustion heat exchanger. Both catalytic and thermal incineration has its advantages and disadvantages.

    The catalytic combustion is auto-thermal at much lower VOC levels than the thermal incineration and thus requires less support fuel supply. The less support fuel needed the less carbon dioxide emissions. Economically and environmentally, catalytic combustion is preferred over thermal incineration at low VOC levels.

    When using adsorption in this case, you must dry the gas from the moisture as the relative moisture content measures up to 95%. If you do not wipe the air from the moisture the moisture will limit the coal beds adsorptions-capacity. When the coal beds starts becoming saturated it is regenerated in its place and desorbate (VOC limits and water) needs to be taken care of. Desorbate is in this case small and can be brought back to the caverns, but can also be treated with appropriate treatment technology.  

  • 2844.
    Ahne, Alexander
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Wikforss, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Projektering av brandskydd för stålkonstruktioner2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 2845.
    Ahnen, M. L.
    et al.
    Swiss Fed Inst Technol, CH-8093 Zurich, Switzerland..
    Jóhannesson, Gudlaugur
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Yassine, M.
    Ist Nazl Fis Nucl, Sez Trieste, I-34127 Trieste, Italy.;Univ Trieste, Dipartimento Fis, I-34127 Trieste, Italy..
    et al.,
    MAGIC and Fermi-LAT gamma-ray results on unassociated HAWC sources2019In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 485, no 1, p. 356-366Article in journal (Refereed)
    Abstract [en]

    The HAWC Collaboration released the 2HWC catalogue of TeV sources, in which 19 show no association with any known high-energy (HE; E greater than or similar to 10 GeV) or very-high-energy (VHE; E greater than or similar to 300 GeV) sources. This catalogue motivated follow-up studies by both the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) and Fermi-LAT (Large Area Telescope) observatories with the aim of investigating gamma-ray emission over a broad energy band. In this paper, we report the results from the first joint work between High Altitude Water Cherenkov (HAWC), MAGIC, and Fermi-LAT on three unassociated HAWC sources: 2HWC J2006+341, 2HWC J1907+084*, and 2HWC J1852+013*. Although no significant detection was found in the HE and VHE regimes, this investigation shows that a minimum 1 degrees extension (at 95 per cent confidence level) and harder spectrum in the GeV than the one extrapolated from HAWC results are required in the case of 2HWC J1852+013*, whilst a simply minimum extension of 0.16 degrees (at 95 per cent confidence level) can already explain the scenario proposed by HAWC for the remaining sources. Moreover, the hypothesis that these sources are pulsar wind nebulae is also investigated in detail.

  • 2846. Ahnen, Max L.
    et al.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics.
    Grishina, T. S.
    et.al.,
    Multiwavelength observations of a VHE gamma-ray flare from PKS 1510-089 in 20152017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 603, article id A29Article in journal (Refereed)
    Abstract [en]

    Context. PKS 1510-089 is one of only a few flat spectrum radio quasars detected in the very-high-energy (VHE, > 100 GeV) gamma-ray band. Aims. We study the broadband spectral and temporal properties of the PKS 1510-089 emission during a high gamma-ray state. Methods. We performed VHE gamma-ray observations of PKS 1510-089 with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes during a long, high gamma-ray state in May 2015. In order to perform broadband modeling of the source, we have also gathered contemporaneous multiwavelength data in radio, IR, optical photometry and polarization, UV, X-ray, and GeV gamma-ray ranges. We construct a broadband spectral energy distribution (SED) in two periods, selected according to VHE gamma-ray state. Results. PKS 1510-089 was detected by MAGIC during a few day-long observations performed in the middle of a long, high optical and gamma-ray state, showing for the first time a significant VHE gamma-ray variability. Similarly to the optical and gamma-ray high state of the source detected in 2012, it was accompanied by a rotation of the optical polarization angle and the emission of a new jet component observed in radio. However, owing to large uncertainty on the knot separation time, the association with the VHE gamma-ray emission cannot be firmly established. The spectral shape in the VHE band during the flare is similar to those obtained during previous measurements of the source. The observed flux variability sets constraints for the first time on the size of the region from which VHE gamma rays are emitted. We model the broadband SED in the framework of the external Compton scenario and discuss the possible emission site in view of multiwavelength data and alternative emission models.

  • 2847. Ahnen, Max L.
    et al.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, AlbaNova, Stockholm, Sweden.
    Li, Liang
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, AlbaNova, Stockholm, Sweden.
    Zottmann, N.
    et al.,
    VERY HIGH ENERGY γ-RAYS from the UNIVERSE'S MIDDLE AGEMAGIC: DETECTION of the z = 0.940 BLAZAR PKS 1441+25 with MAGIC2015In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 815, no 2, article id L23Article in journal (Refereed)
    Abstract [en]

    The flat-spectrum radio quasar PKS 1441+25 at a redshift of z = 0.940 is detected between 40 and 250 GeV with a significance of 25.5σ using the MAGIC telescopes. Together with the gravitationally lensed blazar QSO B0218+357 (z = 0.944), PKS 1441+25 is the most distant very high energy (VHE) blazar detected to date. The observations were triggered by an outburst in 2015 April seen at GeV energies with the Large Area Telescope on board Fermi. Multi-wavelength observations suggest a subdivision of the high state into two distinct flux states. In the band covered by MAGIC, the variability timescale is estimated to be 6.4 ±1.9 days. Modeling the broadband spectral energy distribution with an external Compton model, the location of the emitting region is understood as originating in the jet outside the broad-line region (BLR) during the period of high activity, while being partially within the BLR during the period of low (typical) activity. The observed VHE spectrum during the highest activity is used to probe the extragalactic background light at an unprecedented distance scale for ground-based gamma-ray astronomy.

  • 2848.
    Ahnlund, Joakim
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Short-circuit Contributions from Fully-rated Converter Wind Turbines: Modeling and simulation of steady-state short-circuit contributions from FRC wind turbines in offshore wind power plants2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years there has been an increase in wind power plants installed out at sea. The generated power of wind turbine generators (WTGs) are collected through numerous subsea cables into a single hub, the offshore platform. Subsequently, this platform is interconnected with the onshore main grid through a further stretch of cable. In the event of a fault, a sudden increase in current, so called short-circuit current, will occur somewhere in the system. The short-circuit current will, depending on the duration and location of the fault, potentially harm the power system. In order to accurately determine the dimensions and rating of the equipment installed in the offshore wind power plant (OWPP), the magnitude of this current needs to be studied. Furthermore, depending on the country in which the OWPP is installed, the transmission system operator (TSO) might pose different low-voltage-ride-through (LVRT) requirements on the system. One such requirement is that the installed turbines should provide voltage regulation through injection of reactive current. A type of generator able to achieve this is a so-called fully-rated converter windturbine generator (FRC WTG). Through a power electronic interface, the reactive and active current components of the generator can be freely controlled. With a high level of reactive current injected during a fault in the OWPP, the short-circuit contribution from these FRC WTGs needs to be evaluated. In this master’s thesis, a method has been developed in order to determine the steady-state short-circuit contribution from multiple FRC WTGs. This methodology is based on an iterative algorithm, and has been implemented in the simulation tool PowerFactory. To evaluate the performance of the method, two case studies were performed. In order to improve simulation times, an already existing WTG aggregation model has been implemented to reduce the number of turbines in the test system. From the results, it is concluded that the method obtains the expected FRC WTG short-circuit currents with sufficient accuracy. Furthermore, the deviation from the expected results are evaluated using a numerical tool. This project was initiated and conducted at ABB in Västerås, Sweden.

  • 2849.
    Ahnlund, Joakim
    et al.
    KTH, School of Electrical Engineering (EES).
    Mörée, Gustav
    KTH, School of Electrical Engineering (EES).
    Möjligheter och förutsättningar för lokala likströmsnät i hushåll2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 2850.
    Ahnlund, Josefin
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Statistical Analysis of Conductor-Musician Interaction: With a Focus on Musical Expression2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The kind of interaction occurring between a conductor and musicians while performing a musical piece together is an unique instance of human non-verbal communication. This Musical Production Process (MPP) thus provides an interesting area of research, both from a communication perspective and by its own right. The long term goal of this project is to model the MPP with machine learning methods, for which large amounts of data are required. Since the amount of data available to this master thesis stems from a single recording session (collected at KTH May 2014) a direct modeling of the MPP is unfeasible. As such the thesis can instead be considered as a pilot project which examines pre-requisites for modeling of the MPP. The main aim of the thesis is to investigate how musical expression can be captured in the modeling of the MPP. Two experiments, as well as a theoretical investigation of the MPP, are performed to this end. The first experiment consists of a HMM classification of sound represented by expressive tone parameters extracted by the CUEX algorithm, and labeled by four emotions. This experiment complements the previous classification of conducting gesture in GP-LVM representation performed by Kelly Karipidou on the same data set. The result of the classification implicitly proves that expression has been transferred from conductor to musicians. As the first experiment considers expression over the musical piece as a whole, the second experiment investigates the transfer of expression from conductor to musician on a local level. To this end local representations of the sound and conducting gesture are extracted, the separability of the four emotions are calculated for both representations by use of the Bhattacharyya distance and the results are compared in search for correlation. Some indications of correlation between the representations of sound and gesture are found. The conclusion is nevertheless that the utilized representations of conducting gesture do not capture musical expression to a sufficient extent.

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