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  • 151.
    Al Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Gattami, Ather
    Electrical Engineering and Computer Sciences, UC Berkeley, Berkeley CA, 94720-1770, United States .
    Johansson, Karl Henrik
    Electrical Engineering and Computer Sciences, UC Berkeley, Berkeley CA, 94720-1770, United States .
    Tomlin, Claire Jennifer
    Scania CV AB, Södertälje, Sweden.
    Establishing safety for heavy duty vehicle platooning: a game theoretical approach2011In: IFAC Proceedings Volumes (IFAC-PapersOnline), 2011, p. 3818-3823Conference paper (Refereed)
    Abstract [en]

    It is fuel efficient to minimize the relative distance between vehicles to achievea maximum reduction in air drag. However, the relative distance can only be reduced to acertain extent without endangering a collision. Factors such as the vehicle velocity, the relativevelocity, and the characteristics of the vehicle ahead has a strong impact on what minimumrelative distance can be obtained. In this paper, we utilize optimal control and game theory toestablish safety criteria for heavy duty vehicle platooning applications. The derived results showthat a minimum relative distance of 1.2m can be obtained for two identical vehicles withoutendangering a collision, assuming that there is no delay present in the feedback system. If aworst case delay is present in the system, a minimum relative distance is deduced based uponthe vehicle’s maximum deceleration ability. The relative distance can be reduced if the followervehicle has a greater overall braking capability, which suggests that vehicle heterogeneity andorder has substantial impact. The findings are verified by simulations and the main conclusion isthat the relative distance utilized in commercial applications today can be reduced significantlywith a suitable advanced cruise control system.

  • 152. Al Ismaeil, Kassem
    et al.
    Aouada, Djamila
    Mirbach, Bruno
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Bilateral Filter Evaluation Based on Exponential Kernels2012Conference paper (Refereed)
    Abstract [en]

    The well-known bilateral filter is used to smooth noisy images while keeping their edges. This filter is commonly used with Gaussian kernel functions without real justification. The choice of the kernel functions has a major effect on the filter behavior. We propose to use exponential kernels with L1 distances instead of Gaussian ones. We derive Stein's Unbiased Risk Estimate to find the optimal parameters of the new filter and compare its performance with the conventional one. We show that this new choice of the kernels has a comparable smoothing effect but with sharper edges due to the faster, smoothly decaying kernels.

  • 153.
    Al Karim, Miftah
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    PMU Data Mining in and analysis of suitable algorithm for fault pattern recognition.2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Phasor measurement unit (PMU) is getting much attention in recent days to acquire power system data. It is because PMU provides the opportunity to collect high resolution system. Having a high resolution data provides scopes to monitor a system with different computational methods. Data mining is one of the effective methods. In the age of power system automation high resolution power system data storage and management has become more feasible. Data mining can be implemented on high resolution PMU data and many advantages can be achieved from such an operation.  

    Data mining is a scientific process through which a knowledge or patterns are identified from a large amount of data base. Data mining in power system based on PMU data is getting much focus in the recent years. Some of the prominent research on mining power system data and finding pattern is already going on in this field.

    There are different pattern recognition algorithms deployed in data mining field. Research has also been done to check the efficacy of those algorithms in action.

    In this thesis implementation of existing pattern recognition algorithms based on background study is carried out. Along with it one work-process is proposed to check out the possibilities of data mining in power system regarding fault pattern recognition. The mining process proposed here is a mixture of different existing algorithms and a new algorithm for fault classification. The work here mostly offers a broad perspective of data mining in power system rather than dealing with a specific application.

  • 154.
    Al Karim, Miftah
    et al.
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Chenine, Moustafa
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Zhu, Kun
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Nordström, Lars
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Synchrophasor-based data mining for power system fault analysis2012In: Innovative Smart Grid Technologies (ISGT Europe), 2012 3rd IEEE PES International Conference and Exhibition on, IEEE , 2012, p. 6465843-Conference paper (Refereed)
    Abstract [en]

    Phasor measurement units can provide high resolution and synchronized power system data, which can be effectively utilized for the implementation of data mining techniques. Data mining, based on pattern recognition algorithms can be of significant help for power system analysis, as high definition data is often complex to comprehend. In this paper three pattern recognition algorithms are applied to perform the data mining tasks. The deployment is carried out firstly for fault data classification, secondly for checking which faults are occurring more frequently and thirdly for identifying the root cause of a fault by clustering the parameters behind each scenario. For such purposes three algorithms are chosen, k-Nearest Neighbor, Naïve Bayes and the k-means Clustering.

  • 155.
    Alahakoon, Sanath
    et al.
    Central Queensland University, Australia.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Emerging energy storage solutions for transportation - A review: An insight into road, rail, sea and air transportation applications2015In: Electrical Systems for Aircraft, Railway and Ship Propulsion, ESARS, IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    Increasing usage of hybrid electric vehicles, plug-in electric vehicles and emerging new concepts in transportation such as electric highways have raised the significant role of energy storage solutions for transportation to its highest level. It is impossible to specify a single energy storage solution that can satisfactorily fulfill the varying performance demands of various applications in transportation. This paper will identify some of the most demanded performance requirements from some of the key applications in transportation and assess the suitability of emerging energy storage solutions against those.

  • 156.
    Alahakoon, Sanath
    et al.
    Cent Queensland Univ, Sch Engn & Technol, Ft Wayne, IN 4680 USA. eksell, Mats; Ostlund, Stefan.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Östlund, Stefan
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Emerging Energy Storage Solutions for Transportation Electrification - A view2019In: International Journal of Engineering and Technology Innovation, ISSN 2223-5329, E-ISSN 2226-809X, Vol. 9, no 2, p. 75-90Article, review/survey (Refereed)
    Abstract [en]

    Energy storages have caught the attention of transportation community r the past several years. Rsecent developments in hybrid and plug-in ectric vehicles together with novel concepts in transportation such as ectric highways are the reasons for raising the role of energy orages in transportation to such a significant level. Performance mands for energy storage solutions vary significantly from one ansportation application to the other, making it difficult for the ientific community to converge to a single energy storage solution at caters all. This paper reviews the key performance demands of the jor transportation applications. It also investigates the aracteristics of emerging energy storage solutions and assess their itability for those reviewed transportation applications.

  • 157.
    Ala-Laurinaho, J.
    et al.
    Aalto University, Finland.
    Chicherin, Dmitry
    Aalto University, Finland.
    Du, Zhou
    Aalto University, Finland.
    Simovski, C.
    Aalto University, Finland.
    Zvolensky, T.
    Aalto University, Finland.
    Räisänen, Antti V.
    Aalto University, Finland.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Boriskin, A. V.
    IETR, France.
    Le Coq, L.
    IETR, France.
    Fourn, Erwan
    IETR, France.
    Muhammad, S. A.
    IETR, France.
    Sauleau, Ronan
    IETR, France.
    Vorobyov, Alexander
    IETR, France.
    Bodereau, F.
    TRW Autocruise, France.
    El Haj Shhade, G.
    TRW Autocruise, France.
    Labia, T.
    TRW Autocruise, France.
    Mallejac, P.
    TRW Autocruise, France.
    Åberg, Jan
    MicroComp Nordic AB, Sweden.
    Gustafsson, M.
    MicroComp Nordic AB, Sweden.
    Schier, T.
    MicroComp Nordic AB, Sweden.
    TUMESA - MEMS tuneable metamaterials for smart wireless applications2012In: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012, IEEE , 2012, p. 95-98Conference paper (Refereed)
    Abstract [en]

    This paper describes the main results of the EU FP7 project TUMESA - MEMS tuneable metamaterials for smart wireless applications. In this project, we studied several reconfigurable antenna approaches that combine the new technology of MEMS with the new concept of artificial electromagnetic materials and surfaces (metamaterials and metasurfaces) for realisation of millimetre wave phase shifters and beam-steering devices. MEMS technology allows to miniaturise electronic components, reduce their cost in batch production, and effectively compete with semiconductor and ferroelectric based technologies in terms of losses at millimetre wavelengths. Novel tuneable materials and components proposed in this project perform as smart beam steering devices. Fabricated with MEMS technology in batch and on a single chip, proposed tuneable devices allow substituting of larger and more complex sub-system of, e.g., a radar sensor. This substitution provides a dramatic cost reduction on a system level.

  • 158.
    Alam, Assad
    KTH, School of Electrical Engineering (EES).
    Fuel-Efficient Distributed Control for Heavy Duty Vehicle Platooning2011Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Freight transport demand has escalated and will continue to do so as economiesgrow. As the traffic intensity increases, the drivers are faced with increasinglycomplex tasks and traffic safety is a growing issue. Simultaneously, fossil fuel usageis escalating. Heavy duty vehicle (HDV) platooning is a plausible solution to theseissues. Even though there has been a need for introducing automated HDV platooningsystems for several years, they have only recently become possible to implement.Advancements in on-board and external technology have ushered in new possibilitiesto aid the driver and enhance the system performance. Each vehicle is able to serveas an information node through wireless communication; enabling a cooperativenetworked transportation system. Thereby, vehicles can semi-autonomously travel atshort intermediate spacings, effectively reducing congestion, relieving driver tension,improving fuel consumption and emissions without compromising safety.

    This thesis presents contributions to a framework for the design and implementation of HDV platooning. The focus lies mainly on establishing and validating realconstraints for fuel optimal control for platooning vehicles. Nonlinear and linearvehicle models are presented together with a system architecture, which dividesthe complex problem into manageable subsystems. The fuel reduction potentialis investigated through simulation models and experimental results derived fromstandard vehicles traveling on a Swedish highway. It is shown through analyticaland experimental results that it is favorable with respect to the fuel consumption tooperate the vehicles at a much shorter intermediate spacing than what is currentlydone in commercially available systems. The results show that a maximum fuelreduction of 4.7–7.7 % depending on the inter-vehicle time gap, at a set speedof 70 km/h, can be obtained without compromising safety. A systematic designmethodology for inter-vehicle distance control is presented based on linear quadraticregulators (LQRs). The structure of the controller feedback matrix can be tailoredto the locally available state information. The results show that a decentralizedcontroller gives good tracking performance, a robust system and lowers the controleffort downstream in the platoon. It is also shown that the design methodologyproduces a string stable system for an arbitrary number of vehicles in the platoon,if the vehicle configurations and the LQR weighting parameters are identical for theconsidered subsystems.

    With the results obtained in this thesis, it is argued that a vast fuel reductionpotential exists for HDV platooning. Present commercial systems can be enhancedsignificantly through the introduction of wireless communication and decentralizedoptimal control.

  • 159.
    Alam, Assad
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fuel-Efficient Heavy-Duty Vehicle Platooning2014Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The freight transport industry faces big challenges as the demand for transport and fuel prices are steadily increasing, whereas the environmental impact needs to be significantly reduced. Heavy-duty vehicle (HDV) platooning is a promising technology for a sustainable transportation system. By semi-autonomously governing each platooning vehicle at small inter-vehicle spacing, we can effectively reduce fuel consumption, emissions, and congestion, and relieve driver tension. Yet, it is not evident how to synthesise such a platoon control system and how constraints imposed by the road topography affect the safety or fuel-saving potential in practice.

    This thesis presents contributions to a framework for the design, implementation, and evaluation of HDV platooning. The focus lies mainly on establishing fuel-efficient platooning control and evaluating the fuel-saving potential in practice. A vehicle platoon model is developed together with a system architecture that divides the control problem into manageable subsystems. Presented results show that a significant fuel reduction potential exists for HDV platooning and it is favorable to operate the vehicles at a small inter-vehicle spacing. We address the problem of finding the minimum distance between HDVs in a platoon without compromising safety, by setting up the problem in a game theoretical framework. Thereby, we determine criteria for which collisions can be avoided in a worst-case scenario and establish the minimum safe distance to a vehicle ahead. A systematic design methodology for decentralized inter-vehicle distance control based on linear quadratic regulators is presented. It takes dynamic coupling and engine response delays into consideration, and the structure of the controller feedback matrix can be tailored to the locally available state information. The results show that a decentralized controller gives good tracking performance and attenuates disturbances downstream in the platoon for dynamic scenarios that commonly occur on highways. We also consider the problem of finding a fuel-efficient controller for HDV platooning based on road grade preview information under road and vehicle parameter uncertainties. We present two model predictive control policies and derive their fuel-saving potential. The thesis finally evaluates the fuel savings in practice. Experimental results show that a fuel reduction of 3.9–6.5 % can be obtained on average for a heterogenous platoon of HDVs on a Swedish highway. It is demonstrated how the savings depend on the vehicle position in the platoon, the behavior of the preceding vehicles, and the road topography. With the results obtained in this thesis, it is argued that a significant fuel reduction potential exists for HDV platooning.

  • 160.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Asplund, Fredrik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Behere, Sagar
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Björk, Mattias
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Garcia Alonso, Liliana
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Khaksari, Farzad
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Khan, Altamash
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Kjellberg, Joakim
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Liang, Kuo-Yun
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Lyberger, Rickard
    Scania CV AB.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Nilsson, John-Olof
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Pettersson, Henrik
    Scania CV AB.
    Pettersson, Simon
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Stålklinga, Elin
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Sundman, Dennis
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Zachariah, Dave
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Cooperative driving according to Scoop2011Report (Other academic)
    Abstract [en]

    KTH Royal Institute of Technology and Scania are entering the GCDC 2011 under the name Scoop –Stockholm Cooperative Driving. This paper is an introduction to their team and to the technical approach theyare using in their prototype system for GCDC 2011.

  • 161. Alam, Assad
    et al.
    Besselink, Bart
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Turri, Valerio
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Heavy-Duty Vehicle Platooning for Sustainable Freight Transportation A COOPERATIVE METHOD TO ENHANCE SAFETY AND EFFICIENCY2015In: IEEE CONTROL SYSTEMS MAGAZINE, ISSN 1066-033X, Vol. 35, no 6, p. 34-56Article in journal (Refereed)
    Abstract [en]

    The current system of global trade is largely based on transportation and communication technology from the 20th century. Advances in technology have led to an increasingly interconnected global market and reduced the costs of moving goods, people, and technology around the world [1]. Transportation is crucial to society, and the demand for transportation is strongly linked to economic development. Specifically, road transportation is essential since about 60% of all surface freight transportation (which includes road and rail transport) is done on roads [2]. Despite the important role of road freight transportation in the economy, it is facing serious challenges, such as those posed by increasing fuel prices and the need to reduce greenhouse gas emissions. On the other hand, the integration of information and communication technologies to transportation systems-leading to intelligent transportation systems-enables the development of cooperative methods to enhance the safety and energy efficiency of transportation networks. This article focuses on one such cooperative approach, which is known as platooning. The formation of a group of heavy-duty vehicles (HDVs) at close intervehicular distances, known as a platoon (see Figure 1) increases the fuel efficiency of the group by reducing the overall air drag. The safe operation of such platoons requires the automatic control of the velocity of the platoon vehicles as well as their intervehicular distance. Existing work on platooning has focused on the design of controllers for these longitudinal dynamics, in which simple vehicle models are typically exploited and perfect environmental conditions, such as flat roads, are generally assumed. The broader perspective of how platooning can be effectively exploited in a freight transportation system has received less attention. Moreover, experimental validations of the fuel-saving potential offered by platooning have typically been performed by reproducing the perfect conditions as assumed in the design of the automatic controllers. This article focuses on these two aspects by addressing the following two objectives.

  • 162.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Scania CV AB, SE-15187 Södertälje, Sweden.
    Gattami, Ather
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Tomlin, Claire J.
    UC Berkeley.
    Guaranteeing safety for heavy duty vehicle platooning: Safe set computations and experimental evaluations2014In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 24, no 1, p. 33-41Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the problem of finding a safety criteria between neighboring heavy duty vehicles traveling in a platoon. We present a possible framework for analyzing safety aspects of heavy duty vehicle platooning. A nonlinear underlying dynamical model is utilized, where the states of two neighboring vehicles are conveyed through radar information and wireless communication. Numerical safe sets are derived through the framework, under a worst-case scenario, and the minimum safe spacing is studied for heterogenous platoons. Real life experimental results are presented in an attempt to validate the theoretical results in practice. The findings show that a minimum relative distance of 1.2 m at maximum legal velocity on Swedish highways can be maintained for two identical vehicles without endangering a collision. The main conclusion is that the relative distance utilized in commercial applications today can be reduced significantly with a suitable automatic control system.

  • 163. Alam, Assad
    et al.
    Gattami, Ather
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Suboptimal Decentralized Controller Design for Chain Structures: Applications to Vehicle Formations2011In: IEEE 50th Annual Conference on Decision and Control and European Control Conference, Orlando, December, 2011, IEEE , 2011, p. 6894-6900Conference paper (Refereed)
    Abstract [en]

    We consider suboptimal decentralized controllerdesign for subsystems with interconnected dynamics and costfunctions. A systematic design methodology is presented overthe class of linear quadratic regulators (LQR) for chain graphs.The methodology is evaluated on heavy duty vehicle platooningwith physical constraints. A simulation and frequency analysisis performed. The results show that the decentralized controllergives good tracking performance and a robust system. We alsoshow that the design methodology produces a string stablesystem for an arbitrary number of vehicles in the platoon, ifthe vehicle configurations and the LQR weighting parametersare identical for the considered subsystems.

  • 164.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Experimental evaluation of decentralized cooperative cruise control for heavy-duty vehicle platooning2015In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 38, p. 11-25Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the problem of finding decentralized controllers for heavy-duty vehicle (HDV) platooning by establishing empiric results for a qualitative verification of a control design methodology. We present a linear quadratic control framework for the design of a high-level cooperative platooning controller suitable for modern HDVs. A nonlinear low-level dynamical model is utilized, where realistic response delays in certain modes of operation are considered. The controller performance is evaluated through numerical and experimental studies. It is concluded that the proposed controller behaves well in the sense that experiments show that it allows for short time headways to achieve fuel efficiency, without compromising safety. Simulation results indicate that the model mimics real life behavior. Experiment results show that the dynamic behavior of the platooning vehicles depends strongly on the gear switching logic, which is confirmed by the simulation model. Both simulation and experiment results show that the third vehicle never displays a bigger undershoot than its preceding vehicle. The spacing errors stay bounded within 6.8. m in the simulation results and 7.2. m in the experiment results for varying transient responses. Furthermore, a minimum spacing of -0.6. m and -1.9. m during braking is observed in simulations and experiments, respectively. The results indicate that HDV platooning can be conducted at close spacings with standardized sensors and control units that are already present on commercial HDVs today.

  • 165.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Automatic Control.
    Look-Ahead Cruise Control for Heavy Duty Vehicle Platooning2013In: Proceedings of the 16th International IEEE Annual Conference onIntelligent Transportation Systems (ITSC 2013), IEEE conference proceedings, 2013, p. 928-935Conference paper (Refereed)
    Abstract [en]

    Vehicle platooning has become important for thevehicle industry. Yet conclusive results with respect to thefuel reduction possibilities of platooning remain unclear, inparticular when considering constraints imposed by the topography.The focus of this study is to establish whether itis more fuel-efficient to maintain or to split a platoon that isfacing steep uphill and downhill segments. Two commercialcontrollers, an adaptive cruise controller and a look-aheadcruise controller, are evaluated and alternative novel controlstrategies are proposed. The results show that an improvedfuel-efficiency can be obtained by maintaining the platoonthroughout a hill. Hence, a cooperative control strategy basedon preview information is presented, which initiates the changein velocity at a specific point in the road for all vehiclesrather than simultaneously changing the velocity to maintainthe spacing. A fuel reduction of up to 14% can be obtainedover a steep downhill segment and a more subtle benefit of0.7% improvement over an uphill segment with the proposedcontroller, compared to the combination of the commerciallyavailable cruise controller and adaptive cruise controller thatcould be used for platooning. The findings show that it isboth fuel-efficient and desirable in practice to consider previewinformation of the topography in the control strategy.

  • 166.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Sahlholm, Per
    KTH, School of Electrical Engineering (EES), Automatic Control.
    A Method for Determining an Economical Speed for Heavy Vehicles2008In: Proceedings of the 15th World Congress on Intelligent Transport Systems, World Congress on Intelligent Transport Systems (ITS), 2008Conference paper (Refereed)
  • 167.
    Alaniz Flores, Monica
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Experiment Control Electronics for Spinning Quad Ionospheric Deployer SQUID2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Spinning QUad Ionospheric Deployer (SQUID) is a soundingcrocket experiment developed to test and verify a novel mechanism to deploy wire booms. The SQUID consists of the Rocket Mounted Unit (RMU) and the Free Flying Unit (FFU), the former is attached to the rocket and the latter is ejected. The FFU carries the electronics box (eBox) that controls the system and the boom deployment system known as SCALE. The FFU needs to be independent when has been ejected from the rocket. This thesis work covers the design and manufacture of the SQUID electronics system to control the functionality of the experiment. The control is implemented in a Field Programmable Gate Array (FPGA) using the VHDL language. The integration, testing and validation of software and hardware also is presented here. The SQUID experiment was launched onboard the REXUS-10 rocket from ESRANGE the 23rd February 2011.

  • 168.
    Alaniz, Monica
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Belyayev, Serhiy
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Bergman, David
    Casselbrant, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Honeth, Mark
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Huang, Jiangwei
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Ivchenko, Nickolay
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Laukkanen, Mikko
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Michelsen, Jacob
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Pronenko, Vira
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Paulson, Malin
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Schlick, Georg
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Tibert, Gunnar
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Valle, Mario
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    The SQUID sounding rocket experiment2011In: Proceedings of the 20th ESA Symposium on European Rocket and Balloon Programmes and Related Research, European Space Agency, 2011, p. 159-166Conference paper (Refereed)
    Abstract [en]

    The objective of the SQUID project is to develop and in flight verify a miniature version of a wire boom deployment mechanism to be used for electric field measurements in the ionosphere. In February 2011 a small ejectable payload, built by a team of students from The Royal Institute of Technology (KTH), was launched from Esrange on-board the REXUS-10 sounding rocket. The payload separated from the rocket, deployed and retracted the wire booms, landed with a parachute and was subsequently recovered. Here the design of the experiment and post fight analysis are presented.

  • 169.
    Alayon Glasunov, Andrés
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Prasad, S.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Experimental characterization of the propagation channel along a very large virtual array in a reverberation chamber2014In: Progress in Electromagnetics Research B, ISSN 1937-6472, E-ISSN 1937-6472, no 59, p. 205-217Article in journal (Refereed)
    Abstract [en]

    We show that the combined use of radio frequency absorbers and directive antennas can produce significant changes of the radio propagation channel properties along the positions of a virtual array inside a reverberation chamber. A multidimensional characterization of the channel was performed at 40 antenna positions with spacing of 0:233λ at 1 GHz. The average power, the Ricean K-factor, the coherence bandwidth, the r.m.s. delay spread, the mean delay, the beamforming power angle spectrum and array antenna correlation have been studied for different arrangements in the reverberation chamber. The analysis shows that the joint average over time and frequency channel behavior is, as expected, rather homogeneous along the very large array. However, individual realizations of the channel present a pronounced selective behavior in space, time and frequency with parameters varying along the positions of the virtual array suggesting that a heterogeneous behavior of the radio channels can be emulated in reverberation chambers. An important application of the presented study comprises testing of antenna array designs and algorithms in multipath environments. Further development may lead to Over The Air testing of Multiple Input Multiple Output antenna systems of various sizes, i.e., from small to very large arrays.

  • 170.
    Alayon Glazunov, Andres
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    A Monte Carlo study on the diversity measure of a spherical volume2012In: Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012, 2012, p. 21-24Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate the diversity measure ψ(R h) of MIMO (Multiple-Input Multiple-Output) channels based on the eigenvalues of the full-correlation matrix of the channel matrix R h. We apply this definition to antennas and channels based on the antenna scattering matrix and the spherical vector wave (svw) expansion of the electromagnetic fields. We derive bounds for this diversity measure in an isotropic propagation channel. We further analyze the diversity measure of a spherical volume occupied by decoupled λ/2-dipole antennas by means of Monte Carlo simulations assuming different polarizations, e.g., vertically or horizontally polarizations, 2 orthogonal polarizations and 3 orthogonal polarizations.

  • 171.
    Alayon Glazunov, Andres
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    A survey of the application of the spherical vector wave mode expansion approach to antenna-channel interaction modeling2014In: Radio Science, ISSN 0048-6604, E-ISSN 1944-799X, Vol. 49, no 8, p. 663-679Article in journal (Refereed)
    Abstract [en]

    This paper provides an overview of recent advances in the modeling, analysis, and measurements of interactions between antennas and the propagation channel in multiple antenna systems based on the spherical vector wave mode expansion of the electromagnetic field and the antenna scattering matrix. It demonstrates the importance and usefulness of this approach to gain further insights into a variety of topics such as physics-based propagation channel modeling, mean effective gain, channel correlation, propagation channel measurements, antenna measurements and testing, the number of degrees of freedom of the radio propagation channel, channel throughput, and diversity systems. The paper puts particular emphasis on the unified approach to antenna-channel analysis at the same time as the antenna and the channel influence are separated. Finally, the paper provides the first bibliography on the application of the spherical vector wave mode expansion of the electromagnetic field to antenna-channel interactions.

  • 172.
    Alayon Glazunov, Andres
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Expansion of the Kronecker and Keyhole Channels Into Spherical Vector Wave Modes2011In: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 10, p. 1112-1115Article in journal (Refereed)
    Abstract [en]

    In this letter, we provide additional results on the expansion of wireless channels into spherical vector wave multipole modes. We specialize our results to multiple-input-multiple-output (MIMO) channels with Kronecker-product structure of the correlation matrix: 1) the Kronecker channel, and 2) the Keyhole channel. We show that the Kronecker or Keyhole structure of the multimode channel matrix implies the corresponding structure in the MIMO channel matrix. Moreover, we show that the separability of the joint probability distribution functions of the angle of arrival (AoA) and the angle of departure (AoD), i.e., the independence between the AoAs and the AoDs for co- and cross-polarized components results in a Kronecker-product structure of the full-correlation matrix of the multimode matrix for both the Kronecker and the Keyhole channels.

  • 173.
    Alayon Glazunov, Andres
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Maximum joint transmit-receive MRC gain with antennas exciting spherical vector wave modes up to order l2012In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 48, no 24, p. 1520-1521Article in journal (Refereed)
    Abstract [en]

    Derived is the maximum joint transmit and receive maximum ratio combining (MRC) diversity gain in arbitrary MIMO (multiple-input multiple-output) wireless propagation channels and the corresponding transmit and receive antenna coefficients. Also provided are numerical examples addressing two generic MIMO channel models based on the Kronecker correlation model with Laplacian angle-of-arrival (AoA) and angle-of-departure (AoD) distributions. In the analysis, spherical vector wave multipole modes of order l are considered, including both TE and TM modes.

  • 174.
    Alayon Glazunov, Andres
    et al.
    KTH, School of Electrical Engineering (EES). Lund University, Sweden.
    Gustafsson, Mats
    Molisch, Andreas F.
    On the Physical Limitations of the Interaction of a Spherical Aperture and a Random Field2011In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 59, no 1, p. 119-128, article id 5618544Article in journal (Refereed)
    Abstract [en]

    This paper derives physical limitations on the interactions of antennas exciting TM or TE modes (but not both) and wireless propagation channels. The derivation is based on the spherical vector wave expansion of the electromagnetic field outside a sphere circumscribing the antennas. The result is an extension of the seminal work of Chu on the classical limitations on maximum antenna gain and radiation Q. Rather than maximizing antenna gain in a single direction we obtain physical limitations on the antenna gain pattern, which is directly translated to more condensed parameters, i.e., the instantaneous effective gain G(i) and the mean effective gain G(e) if instantaneous realizations or correlation statistics of the expansion coefficients of the electromagnetic field are known, spectively. The obtained limitations are on the maximum of G(i)/Q and G(e)/Q, which establish a trade-off between link gain and Q.

  • 175.
    Alayon Glazunov, Andres
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Kolmonen, Veli-Matti
    Aalto University, Finland.
    Laitinen, Tommi
    Aalto University, Finland.
    MIMO Over-the-Air Testing2012In: LTE-Advanced and Next Generation Wireless Networks: Channel Modelling and Propagation, Chichester, U.K.: John Wiley & Sons, 2012, p. 411-441Chapter in book (Refereed)
  • 176.
    Alayon Glazunov, Andres
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Lai, Zhihua
    Ranplan Wireless Network Design Ltd., United Kingdom.
    Zhang, Jie
    University of Sheffield, United Kingdom.
    Outdoor-Indoor Channel2012In: LTE-Advanced and Next Generation Wireless Networks: Channel Modelling and Propagation, Chichester, U.K.: John Wiley & Sons, 2012, p. 123-151Chapter in book (Refereed)
  • 177.
    Alayon Glazunov, Andres
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Prasad, Sathyaveer
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Bolin, Thomas
    Prytz, Kjell
    Impact of Scattering Within a Multipath Simulator Antenna Array on the Ricean Fading Distribution Parameters in OTA Testing2014In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 62, no 6, p. 3257-3269Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate the unwanted scattering that exists within the multipath simulator (MPS) array antennas employed in over the air (OTA) testing of mobile terminals. The impact of scattering is evaluated in terms of the measurement uncertainty of the average received power and the Ricean K-factor. The maximum ratio combining diversity is investigated for a generic device under test comprising two half-wavelength dipole antennas. We provide closed-form expressions for the uncertainties of the average received power and the Ricean K-factor for a uniform circular array of MPS antennas and a 2-D uniformly distributed angle-of-arrival spectrum. We also derive the maximum number of MPS antennas and the minimum ring radius of the MPS system as a function of the separation between the most distant antenna elements if the device under test employs a uniform linear array. As a result, we provide design guidelines for MPS array in terms of the number antennas, the radius of the MPS array and the wavelength of the carrier frequency.

  • 178.
    Alayon Glazunov, Andres
    et al.
    TeliaSonera.
    Wang, Ying
    Zetterberg, Per
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Experimental Evaluation of CW MIMO Channel Capacity in Urban Multicell Environment2006Conference paper (Refereed)
  • 179.
    Alayon Glazunov, Andres
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Zhang, Jie
    University of Bedfordshire.
    Clustering impact on the statistics of the multipole expansion coefficients of a wireless channel2011In: Progress in Electromagnetics Research Symposium, 2011, p. 603-607Conference paper (Refereed)
    Abstract [en]

    It has been widely known that experimental results show that multipath components seem to arrive at the receiver in concentrated groups. These groups of multipath components, or clusters, are usually a result of scattering from large physical structures. Their impact on the capacity of Multiple-Input Multiple-Output (MIMO) systems has been widely studied. However, their impact on the spherical vector waves (svw) expansion of the propagation channel has not yet been addressed in the literature. As we have recently shown, a svw expansion provides a compact and straightforward representation of both antennas and channels. This can potentially facilitate designing antennas tailored to take advantage of the spatial and polarimetric characteristics of the propagation environment, which is essential to the deployment of efficient wireless networks. In this paper, we therefore study the impact of clustering on the first and second order statistics of the multimode expansion coefficients. We adopt the simulation approach to exemplify our results and provide numerical examples.

  • 180.
    Alayon Glazunov, Andres
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Zhang, Jie
    The University of Sheffield.
    On Some Optimal MIMO Antenna Coefficients in Multipath Channels2011In: Progress in Electromagnetics Research B, ISSN 1937-6472, E-ISSN 1937-6472, Vol. 35, p. 87-109Article in journal (Refereed)
    Abstract [en]

    This paper derives some optimum transmit and receive antenna coefficients in wireless multipath channels based on the spherical vector wave multimode expansion of the multiple-input multiple-output (MIMO) channel matrix. The derived antenna coefficients satisfy the following specific optimization criteria: (i) maximum MIMO mean effective link gain (link MEG) based on the multimode channel realizations or (ii) maximum MIMO link MEG based on the multimode correlation matrix or (iii) correlation minimization by diagonalization of the MIMO full-correlation matrix. It is shown that the proposed approach leads to matrix equations belonging to the nearest Kronecker product (NKP) problem family, which in general have no trivial solution. However, we show that exact solutions are provided to the posed NKP problems under the assumption of the Kronecker model for the MIMO full-correlation matrix. The results are illustrated by numerical examples. The proposed approach is a complement to existing antenna pattern analysis methods.

  • 181.
    Alayon Glazunov, Andres
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Zhang, Jie
    Lund University.
    Some Examples of Uncorrelated Antenna Radiation Patterns for MIMO Applications2011In: Progress in Electromagnetics Research Symposium, 2011, p. 598-602Conference paper (Refereed)
    Abstract [en]

    In this paper, we provide some examples of an approach resulting in uncorrelatedantenna radiation patterns at both ends of a MIMO (Multiple-Input Multiple-Output) wireless link in a given propagation channel. The patterns of antennas exciting dipole or dipole and quadrupole TE and TM modes are analyzed for two generic MIMO channel models based on the Kronecker correlation model with Laplacian angle-of-arrival (AoA) and angle-of-departure (AoD) distributions. The presented results are of a fundamental nature and essential to achieve the promise of MIMO systems.

  • 182.
    Alberer, Daniel
    et al.
    Johannes Kepler University.
    Hjalmarsson, HåkanKTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.del Re, LuigiJohannes Kepler University.
    Identification for Automotive Systems2012Collection (editor) (Refereed)
  • 183.
    Alberer, Daniel
    et al.
    Johannes Kepler University.
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    del Re, Luigi
    Johannes Kepler University.
    System Identification for Automotive Systems: Opportunities and Challenges2012In: Identification for Automotive Systems / [ed] Daniel Alberer, Håkan Hjalmarsson, Luigi del Re, Springer London, 2012, p. 1-10Chapter in book (Refereed)
    Abstract [en]

    Without control many essential targets of the automotive industry could not be achieved. As control relies directly or indirectly on models and model quality directly influences the control performance, especially in feedforward structures as widely used in the automotive world, good models are needed. Good first principle models would be the first choice, and their determination is frequently difficult or even impossible. Against this background methods and tools developed by the system identification community could be used to obtain fast and reliably models, but a large gap seems to exist: neither these methods are sufficiently well known in the automotive community, nor enough attention is paid by the system identification community to the needs of the automotive industry. This introduction summarizes the state of the art and highlights possible critical issues for a future cooperation as they arose from an ACCM Workshop on Identification for Automotive Systems recently held in Linz, Austria.

  • 184.
    Alberer, Daniel
    et al.
    Johannes Kepler Univ Linz, Inst Design & Control Mechatron Syst, Altenbergerstr 69, A-4040 Linz, Austria..
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    del Re, Luigi
    Johannes Kepler Univ Linz, Inst Design & Control Mechatron Syst, Altenbergerstr 69, A-4040 Linz, Austria..
    System Identification for Automotive Systems: Opportunities and Challenges2012In: IDENTIFICATION FOR AUTOMOTIVE SYSTEMS / [ed] Alberer, D Hjalmarsson, H DelRe, L, SPRINGER-VERLAG BERLIN , 2012, p. 1-+Conference paper (Refereed)
    Abstract [en]

    Without control many essential targets of the automotive industry could not be achieved. As control relies directly or indirectly on models and model quality directly influences the control performance, especially in feed-forward structures as widely used in the automotive world, good models are needed. Good first principle models would be the first choice, and their determination is frequently difficult or even impossible. Against this background methods and tools developed by the system identification community could be used to obtain fast and reliably models, but a large gap seems to exist: neither these methods are sufficiently well known in the automotive community, nor enough attention is paid by the system identification community to the needs of the automotive industry. This introduction summarizes the state of the art and highlights possible critical issues for a future cooperation as they arose from an ACCM Workshop on Identification for Automotive Systems recently held in Linz, Austria.

  • 185.
    Alday, Juan
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Roth, Lorenz
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Ivchenko, Nickolay
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Retherford, Kurt D.
    Becker, Tracy M.
    Molyneux, Philippa
    Saur, Joachim
    New constraints on Ganymede's hydrogen corona: Analysis of Lyman-alpha emissions observed by HST/STIS between 1998 and 20142017In: Planetary and Space Science, ISSN 0032-0633, E-ISSN 1873-5088, Vol. 148, p. 35-44Article in journal (Refereed)
    Abstract [en]

    Far-ultraviolet observations of Ganymede's atmospheric emissions were obtained with the Space Telescope Imaging Spectrograph (STIS) onboard of the Hubble Space Telescope (HST) on several occasions between 1998 and 2014. We analyze the Lyman-alpha emission from four HST campaigns in order to constrain the abundance and variation of atomic hydrogen in Ganymede's atmosphere. We apply a forward model that estimates surface reflection and resonant scattering in an escaping corona of the solar Lyman-alpha flux, taking into account the effects of the hydrogen in the interplanetary medium. The atmospheric emissions around Ganymede's disk derived for the observations taken between 1998 and 2011 are consistent with a hydrogen corona in the density range of (5-8) x 10(3) cm(-3) at the surface. The hydrogen density appears to be generally stable in that period. In 2014, Ganymede's corona brightness is approximately 3 times lower during two observations of Ganymede's trailing hemisphere and hardly detectable at all during two observations of the leading hemisphere. We also investigate extinction of Ganymede's coronal emissions in the Earth's upper atmosphere or geocorona. For small Doppler shifts, resonant scattering in the geocorona of the moon corona emissions can effectively reduce the brightness observed by HST. In the case of the 2014 leading hemisphere observations, an estimated extinction of 80% might explain the non-detection of Ganymede's hydrogen corona. Geocoronal extinction might also explain a previously detected hemispheric difference from Callisto's hydrogen corona.

  • 186.
    Alday Parejo, Juan
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Ganymede's hydrogen corona and FUV albedo from HST/STIS images2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ganymede, the largest moon in our Solar System, has been a target for intensive scientific research during the past decades. Since 1998, the Space Telescope Imaging Spectrograph (STIS) onboard of the Hubble Space Telescope (HST) has observed it in five different HST campaigns, operating in a wavelength range between 1150-1730 Å. The images were obtained when Ganymede was located at different orbital phase, providing information about both the trailing and leading hemispheres, and allowing for the search of potential hemispherical and time variability. Here, we analyze Ganymede’s HST/STIS observations in the search for a hydrogen exosphere and the study of the far-ultraviolet (FUV) albedo at different wavelengths. The hydrogen corona is expected to scatter sunlight at the Lyman- wavelength (1216 Å), which is within STIS’ spectral range. We analyze the observations at this particular wavelength, and derive models for the different sources of emission that are expected to contribute to the signal. We also estimate the potential extinction of Ganymede’s coronal emissions in the Earth’s upper atmosphere, which can be up to 85%. The comparison between the HST/STIS images and the model allows us to detect the hydrogen exosphere, which we estimate to be in a range of approximately (2-8) 103 cm􀀀3. The atomic hydrogen abundance in Ganymede’s atmosphere during HST campaign 13328 appears to be significantly lower, which could be related to differences in the plasma magnetospheric environment. We study Ganymede’s FUV albedo comparing the reflectance at different wavelengths, and potential difference between leading and trailing hemispheres. We find out that the trailing hemisphere is brighter than the leading side for < 1600 Å. This dichotomy is opposite to the previous results reported for > 2000 Å, where the leading hemisphere is actually brighter. Hence, there is a spectral inversion of Ganymede’s surface reflectivity at some wavelength in the range 1600-2000 Å. We also find out that the reflectivity of the surface increases for < 1400 Å, which might be related to space weathering processes on the surface.

  • 187.
    Aldayel, Omar
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Evaluation of MIMO Non- Stationarity2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The transmission performance of MIMO systems can be highly improved under stationary channel conditions where the channel statistics are constant. Unfortunately, mobile radio channels are not stationary all the time. Instead, they are stationary for finite time durations, so-called the stationarity regions. If these stationarity regions are relatively large, then the channel statistics can be utilized during each stationarity region to enhance the transmission performance. Therefore, it is necessary to examine the stationarity of mobile channels and characterize the stationarity regions. This thesis investigates the non-stationarity of measured MIMO channels and proposes some stationarity metrics to measure it. These metrics are: the CMD proposed by [], NCMD and DES. Each one of the metrics is relevant to different types of transmission schemes and scenarios. The CMD may not be accurate for some transmission scenarios; therefore, the NCMD, which is a normalized version of CMD, is proposed. Theoretically, the NCMD can be at most 100% higher than the CMD for a 4x4 MIMO system. For beamforming scenario, the DES metric can be used to describe the non-stationarity of few eigenvectors taken from the channel variance. Under the measured MIMO channels, it was found that the CMD overestimates the stationarity regions compared to the NCMD and DES metrics particularly under the NLOS routes.

  • 188.
    Aldayel, Omar
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. King Saud University, Saudi Arabia.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Alshebeili, Saleh A.
    King Saud University, Saudi Arabia.
    Evaluation of MIMO channel non-stationarity2013In: 2013 Proceedings of the 21st European Signal Processing Conference (EUSIPCO), IEEE , 2013, p. 6811769-Conference paper (Refereed)
    Abstract [en]

    Several MIMO processing algorithms have been proposed that exploit long-term channel statistics, relaying on the critical assumption that this long-term information is valid long enough. In this paper, we consider the Correlation Matrix Distance (CMD) method previously proposed for the evaluation of MIMO channel non-stationarity. We highlight a couple of problems with the CMD measure and propose two new metrics that are more appropriate for non-stationarity evaluation. The performance of the CMD method and new correlation matrix distance metrics is investigated using measured 4×4 MIMO channels. Both Line-of-Sight (LOS) and Non-LOS (NLOS) environments are considered.

  • 189.
    Alderisio, Francesco
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Pinning Control of Networks: an Event-Triggered Approach2013Student paper other, 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis we present an algorithm for distributed event-triggered pinning control of a network of nonlinear oscillators. In order to extend the concepts of connected, switching connected and slow switching topology to a pinning control scenario, we introduce the denitions of pinned, switching pinned and frequently pinned topology respectively. For each of these three topologies we try to identify the conditions under which the network achieves exponential convergence of the error norm, find a lower bound for the rate of convergence and prove that the trigger sequences do not exhibit Zeno behavior. Some numerical results are presented for each of the considered scenarios; further numerical results are presented for four elementary static topologies.

  • 190. Alegre, Daniel
    et al.
    Bergsåker, Henric
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Gasior, Pawel
    Kubkowska, Monika
    Kowalska-Strzeciwilk, Ewa
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Tabares, Francisco L.
    Study of correlation of deuterium content in a-C:D dust induced by laser irradiation from the co-deposited surface with the grain size and velocity2014In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T161, p. 014010-Article in journal (Refereed)
    Abstract [en]

    In the study described here, the laser ablation method was applied to clean thick (40-60 m) a-C: D co-deposits on the ALT-II limiter blade from the TEXTOR tokamak, and at the same time to characterize the ejected particles formed during ablation and measure the amount of fuel carried by them. Ablation was accomplished by similar to 3.5 ns, 0.5 J Nd: YAG laser pulses in either vacuum or an O-2 atmosphere at different pressures. Fast camera tracking of the process provided an estimate of the population and velocity of up to 100ms(-1) for larger dust particles. In the same experiment, the dust particles were caught using ultra-light Si aerogel collectors placed in front of the ablation target. SEM analysis of aerogel surfaces verified the speed estimate, providing the trapped particles' size distribution and particle yield during ablation. The D/C atomic concentration ratio was measured with the 3HE ion beam nuclear reaction analysis method in deposited layers before ablation and with a micro-ion beam in individual particles on aerogel collectors. This indicated that most of the D was thermally released during ablation, leaving no more than 5% of its original amount in the particles. The effect of ablation conditions on the acceleration of ejected particles, their population, composition and D content is the main subject of this paper.

  • 191.
    Alenezi, Ali
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Evaluation of Precoder Designs Using Measured MIMO Channels2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    MIMO transceiver designs rely mainly on the knowledge of channel state information (CSI) at the transmitter and receiver sides of a communication link. In most  practical scenarios due to the fast fading channels, the transmitter side can only have statistical (or long-term) information about the channel. This thesis investigates and compares five MIMO transceiver designs over a measured 8x4 MIMO channel obtained from ERICSSON in terms of Bit-Error-Rate. Three of the algorithms use statistical channel information (CSI) at the transmitter side and instantaneous channel information at the receiver side, one of the algorithms uses instantaneous channel information at both the transmitter and receiver sides, and one algorithm uses no channel information at the transmitter and instantaneous channel information at the receiver side. The main target of this study is a recently long-term precoder design proposed in [1] which previously has showed good performance compared to other long-term precoder designs on a simulated channel. In the evaluation of the precoder designs on the measured MIMO channel, the precoder in [1] outperformed others long-term precoders and performed near to performance the short-term precoder in [5] on the slow and line-of-sight (LOS) channels. On the fast channels the long-term precoder in [1] works better than the long-term precoders but relatively far from the performance of the short-term precoder.

  • 192. Alesii, Roberto
    et al.
    Congiu, Roberto
    Santucci, Fortunato
    Di Marco, Piergiuseppe
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Architectures and protocols for fast identification in large-scale RFID systems2014In: ISCCSP 2014 - 2014 6th International Symposium on Communications, Control and Signal Processing, Proceedings, 2014, p. 243-246Conference paper (Refereed)
    Abstract [en]

    Passive tags based on backscattered signals yield low energy consumption for large-scale applications of RFIDs. In this paper, system architectures and protocol enhancements for fast identifications in ISO/IEC 18000-6C systems that integrate UWB technology are investigated. The anti-collision protocol is studied by considering various tag populations. A novel algorithm is proposed to adapt the UHF air interface parameters with the use of UWB ranging information. The results show that the proposed algorithm yields up to 25% potential performance improvement compared to the ISO/IEC 18000-6C standard.

  • 193. Alexandre, Seuret
    et al.
    Dimarogonas, Dimos V.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Automatic Control.
    Consensus of Double Integrator Multi-agents under Communication Delay2009In: IFAC Proceedings Volumes (IFAC-PapersOnline), 2009, p. 376-381Conference paper (Refereed)
    Abstract [en]

    This paper deals with the consensus problem under network induced communication delays. It is well-known that introducing a delay generally leads to a reduce of the performance or to instability. Thus, investigating the impact of time-delays in the consensus problem is an important issue. Another important issue is to obtain an estimate of the convergence rate, which is not straightforward when delays appear in the network. In this paper, the agents are modelled as double integrator systems. It is assumed that each agent receives instantaneously its own output information but receives the information from its neighbors after a constant delay. A stability criterion is provided based on Lyapunov-Krasovskii techniques and is expressed in terms of LMI. An expression of the consensus equilibrium which depends on the delay and on the initial conditions taken in an interval is derived. The results are supported through several simulations for different network symmetric communication schemes.

  • 194. Alexandridis, A.
    et al.
    Charonyktakis, P.
    Makrogiannakis, A.
    Papakonstantinou, A.
    Papadopouli, Maria
    KTH, School of Electrical Engineering (EES).
    Forthroid on android: A QR-code based information access system for smart phones2011Conference paper (Refereed)
    Abstract [en]

    The Forthroid is a location-based system that "augments" physical objects with multimedia information and enables users to receive information about physical objects or request services related to physical objects. It employs computer-vision techniques and Quick Response codes (QR-codes). We have implemented a prototype on Android platforms and evaluated its performance with systems metrics and subjective tests. We discuss our findings and challenges in prototyping on Android OS. The analysis indicates that the network and the server are the main sources of delay, while the CPU load may vary depending on the specific Forthroid operation. The preliminary subjective test results suggest that users tolerate these delays and the offered services can be particularly useful.

  • 195. Alexeev, I. I.
    et al.
    Belenkaya, E. S.
    Bobrovnikov, S. Yu.
    Kalegaev, V. V.
    Cumnock, Judy
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Blomberg, Lars G.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Magnetopause mapping to the ionosphere for northward IMF2007In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 25, no 12, p. 2615-2625Article in journal (Refereed)
    Abstract [en]

    We study the topological structure of the magnetosphere for northward IMF. Using a magnetospheric magnetic field model we study the high-latitude response to prolonged periods of northward IMF. For forced solar wind conditions we investigate the location of the polar cap region, the polar cap potential drop, and the field-aligned acceleration potentials, depending on the solar wind pressure and IMF B-y and B-x changes. The open field line bundles, which connect the Earth's polar ionosphere with interplanetary space, are calculated. The locations of the magnetospheric plasma domains relative to the polar ionosphere are studied. The specific features of the open field line regions arising when IMF is northward are demonstrated. The coefficients of attenuation of the solar wind magnetic and electric fields which penetrate into the magnetosphere are determined.

  • 196.
    Alexiou, Nikolaos
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Basagiannis, S.
    Petridou, S.
    Formal security analysis of near field communication using model checking2016In: Computers & security (Print), ISSN 0167-4048, E-ISSN 1872-6208, Vol. 60, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Near field communication (NFC) is a short-range wireless communication technology envisioned to support a large gamut of smart-device applications, such as payment and ticketing. Although two NFC devices need to be in close proximity to communicate (up to 10 cm), adversaries can use a fast and transparent communication channel to relay data and, thus, force an NFC link between two distant victims. Since relay attacks can bypass the NFC requirement for short-range communication cheaply and easily, it is important to evaluate the security of NFC applications. In this work, we present a general framework that exploits formal analysis and especially model checking as a means of verifying the resiliency of NFC protocol against relay attacks. Toward this goal, we built a continuous-time Markov chain (CTMC) model using the PRISM model checker. Firstly, we took into account NFC protocol parameters and, then, we enhanced our model with networking parameters, which include both mobile environment and security-aware characteristics. Combining NFC specifications with an adversary's characteristics, we produced the relay attack model, which is used for extracting our security analysis results. Through these results, we can explain how a relay attack could be prevented and discuss potential countermeasures.

  • 197.
    Alexiou, Nikolaos
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Basagiannis, S.
    Petridou, S.
    Security analysis of NFC relay attacks using probabilistic model checking2014In: IWCMC 2014 - 10th International Wireless Communications and Mobile Computing Conference, IEEE , 2014, p. 524-529Conference paper (Refereed)
    Abstract [en]

    Near Field Communication (NFC) is a short-ranged wireless communication technology envisioned to support a large gamut of smart-device applications, such as payment and ticketing applications. Two NFC-enabled devices need to be in close proximity, typically less than 10 cm apart, in order to communicate. However, adversaries can use a secret and fast communication channel to relay data between two distant victim NFC-enabled devices and thus, force NFC link between them. Relay attacks may have tremendous consequences for security as they can bypass the NFC requirement for short range communications and even worse, they are cheap and easy to launch. Therefore, it is important to evaluate security of NFC applications and countermeasures to support the emergence of this new technology. In this work we present a probabilistic model checking approach to verify resiliency of NFC protocol against relay attacks based on protocol, channel and application specific parameters that affect the successfulness of the attack. We perform our formal analysis within the probabilistic model checking environment PRISM to support automated security analysis of NFC applications. Finally, we demonstrate how the attack can be thwarted and we discuss the successfulness of potential countermeasures.

  • 198.
    Alexiou, Nikolaos
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Gisdakis, Stylianos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Laganà, Marcello
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Towards a secure and privacy-preserving multi-service vehicular architecture2013In: 2013 IEEE 14th International Symposium on a World of Wireless, Mobile and Multimedia Networks, WoWMoM 2013, IEEE , 2013, p. 6583472-Conference paper (Refereed)
    Abstract [en]

    Intensive efforts in industry, academia and standardization bodies have brought vehicular communications (VC) one step before commercial deployment. In fact, future vehicles will become significant mobile platforms, extending the digital life of individuals with an ecosystem of applications and services. To secure these services and to protect the privacy of individuals, it is necessary to revisit and extend the vehicular Public Key Infrastructure (PKI)-based approach towards a multi-service security architecture. This is exactly what this work does, providing a design and a proof-of-concept implementation. Our approach, inspired by long-standing standards, is instantiated for a specific service, the provision of short-term credentials (pseudonyms). Moreover, we elaborate on its operation across multiple VC system domains, and craft a roadmap for further developments and extensions that leverage Web-based approaches. Our current results already indicate our architecture is efficient and can scale, and thus can meet the needs of the foreseen broad gamut of applications and services, including the transportation and safety ones.

  • 199.
    Alexiou, Nikolaos
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Laganá, Marcello
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Gisdakis, Stylianos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Khodaei, Mohammad
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    VeSPA: Vehicular security and privacy-preserving architecture2013In: HotWiSec 2013: Proceedings of the 2013 ACM Workshop on Hot Topics on Wireless Network Security and Privacy, 2013, p. 19-23Conference paper (Refereed)
    Abstract [en]

    Vehicular Communications (VC) are reaching a near deploment phase and will play an important role in improving road safety, driving efficiency and comfort. The industry and the academia have reached a consensus for the need of a Public Key Infrastructure (PKI), in order to achieve security, identity management, vehicle authentication, as well as preserve vehicle privacy. Moreover, a gamut of proprietary and safety applications, such as location-based services and pay-as-you-drive systems, are going to be offered to the vehicles. The emerging applications are posing new challenges for the existing Vehicular Public Key Infrastructure (VPKI) architectures to support Authentication, Authorization and Accountability (AAA), without exposing vehicle privacy. In this work we present an implementation of a VPKI that is compatible with the VC standards. We propose the use of tickets as cryptographic tokens to provide AAA and also preserve vehicle privacy against adversaries and the VPKI. Finally, we present the efficiency results of our implementation to prove its applicability.

  • 200. Alfier, A.
    et al.
    Annibaldi, Silvia Valeria
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics. Euratom/ENEA Association, Italy.
    Bonomo, F.
    Buratti, P.
    Franz, P.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Marrelli, L.
    Pasqualotto, R.
    Piovesan, P.
    Spizzo, G.
    Energy confinement in high current RFX-mod plasmas2007In: 34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts, 2007, no 1, p. 415-418Conference paper (Refereed)
1234567 151 - 200 of 11500
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