| 1. |
- Lyamin, Nikita, 1989-
(författare)
-
Performance evaluation of safety critical ITS-G5 V2V communications for cooperative driving applications
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Intelligent Transport Systems (ITS) are aiming to provide innovative services related to different modes of transport and traffic management, and enable various users to be better informed and make safer, more coordinated and smarter use of transport networks. Cooperative-ITS (C-ITS) support connectivity between vehicles, vehicles and roadside infrastructure, traffic signals as well as with other road users. In order to enable vehicular communications European Telecommunication Standards Institute (ETSI) delivered ITS-G5 -- a of set of C-ITS standards. Considering the goals of C-ITS, inter-vehicle communications should be reliable and efficient.The subject of this thesis is evaluation of the performance, efficiency, and dependability of ITS-G5 communications for cooperative driving applications support. This thesis includes eight scientific papers and extends the research area in three directions: evaluation of the performance of ITS-G5 beaconing protocols; studying the performance of ITS-G5 congestion control mechanisms; and studying the radio jamming Denial-of-Service (DoS) attacks and their detection methods.First, an overview of currently available and ongoing standardization targeting communications in C-ACC/platooning cooperative driving applications is provided. Then, as part of the first research direction, we demonstrate via a number of studies, that the adaptive beaconing approach where message generation is coupled to the speed variation of the originating ITS-s may lead to a message synchronization effect in the time domain when vehicles follow mobility scenarios that involve cooperative speed variation. We explain in detail the cause of this phenomenon and test it for a wide range of parameters. In relation to the second problem, we, first, study the influence of different available ITS-G5 legitimate setups on the C-ACC/platooning fuel efficiency and demonstrate that proper communication setup may enhance fuel savings. Then we thoroughly study the standardization of the congestion control mechanism for ITS-G5, which will affect the operation of all cooperative driving C-ITS applications as a mandatory component. We study the influence of congestion control on application performance and give recommendations for improvement to make the congestion control to target at optimizing the applications performance metrics. In the scope of the last research direction, we propose two real-time jamming DoS detection methods. The main advantage of our detection techniques is their short learning phase that not exceed a few seconds and low detection delay of a few hundreds of milliseconds. Under some assumptions, the proposed algorithms demonstrates the ability to detect certain types of attacks with high detection probability.
|
|
| 2. |
- Foultier, Christophe, 1972-
(författare)
-
Regimes of Hospitality : Urban Citizenship between Participation and Securitization – the Case of the Multiethnic French Banlieue
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis analyzes various local development policies in Europe’s big urban areas. Striving to understand the respective places accorded to the measures to increase the participation of the inhabitants on the one hand, and to improve for security and public peace in the context of social and territorial policies on the other, I examine how urban policies define models of urban citizenship. The empirical work concerns two sites in the greater metropolitan area of Paris, Le Franc-Moisin–Bel-Air in Saint-Denis and Les Cinq Quartiers in Les Mureaux. It consists of an analysis of public documents as well as a series of interviews and observations. This methodological approach serves to gain an understanding of how participative and security procedures emerge in the history of French urban policy and how these norms interact locally.By investigating the overlap of security politics and participatory devices, I demonstrate that deprived areas do not have access to an adequate form of intervention to meet the expectations and needs of its inhabitants, who are squeezed between a logic of development reluctantly accepted by, but rarely negotiated with its inhabitants, and a logic of security that often leads to the confinement of residents to their respective areas. The thesis thus demonstrates how institutional interventions in multiethnic areas can fuel feelings of suspicion be-tween local stakeholders and civic distrust. Indeed, the participatory procedures that are developed in urban strategies influence the conduct of participants on matters of identity and belonging and can intensify socio-ethnic stigmatization. This effect provides me with a critical standpoint on new techniques of government. The local partners of the state develop daily routines in urban strategies that contribute to articulating participatory devices and security procedures. I claim that the results from this process are “regimes of hospitality”.
|
|
| 3. |
- Hoang, Hoai, 1976-
(författare)
-
Enhancing the Performance of Distributed Real-time Systems
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Advanced embedded systems can consist of many sensors, actuators and processors that are deployed on one or several boards, while having a demand of interacting with each other and sharing resources. Communication between different components usually has strict timing constraints. There is thus a strong need to provide solutions for time critical communication. This thesis focuses on both the support of real-time services over standard switched Ethernet networks and the improvement of systems' real-time characteristics, such as reducing delay and jitter in processors and on communication links.Switched Ethernet has been chosen in this work because of its major advantages in industry; it supports higher bit-rates than most other current LAN (Local Area Network) technologies, including field buses, still at a low cost. We propose using a star network topology with a single Ethernet switch. Each node is connected to a separate port of the switch via a full-duplex link, thereby eliminating collisions. A solid real-time communication protocol for switched Ethernet networks is proposed in the thesis, including a real-time layer between the Ethernet layer and the TCP/IP suite. The network has the capability of supporting both real-time and non real-time traffic and assuring adaptation to the surrounding protocol standards.Most embedded systems work in a dynamic environment, where the precise behavior of the network traffic can usually not be predicted. To support real-time services, we have chosen the Earliest Deadline scheduling algorithm (EDF) because of its optimality, high efficiency and suitability for being used in adaptive schemes. To be able to increase the amount of guaranteed real-time traffic, the notion of Asymmetric Deadline Partitioning Scheme (ADPS) is introduced. ADPS allows distribution of the end-to-end deadline of a message, sent from any source node in the network to any destination node via the switch, into two sub-deadlines, one for each hop according to the load of the physical link that it must traverse.For the EDF scheduling algorithm, the feasibility test is one of the most important techniques that provides us with information about whether or not the real-time traffic can be guaranteed by the network. With the same computational complexity as the feasibility test, a method has been developed to compute the minimum EDF-feasible deadline for a real-time task. The importance of this method in real-time applications lies in that it can be effectively used to reduce the response times of specific control activities or limit their input-output jitter. To allow more flexibility in the control of delay and jitter in real-time systems, a general approach for reducing task deadlines according to the requirements of individual tasks has been developed. The method allows the user to specify a deadline reduction factor for each task in order to better exploit the available slack according to the tasks' actual requirements.
|
|
| 4. |
- Hoang, Le-Nam, 1984-
(författare)
-
Relaying for Timely and Reliable Applications in Wireless Networks
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many emerging applications based on wireless networks involve distributed control. This implies high requirements on reliability, but also on predictable maximum delay. Further, for applications, it is vital to use off-the-shelf components, both due to cost constraints and requirements on interoperability with existing networks. This, in turn, implies that concurrent transmissions and multiuser detection are seldom possible. Instead, half-duplex time-division multiple access (TDMA) is typically used. Aiming to reduce the packet error rate given a deadline (a set of TDMA time-slots), this thesis proposes a relaying scheme, which can be implemented on top of off-the-shelf components. The relaying scheme selects the best sequence of relayers, given the number of time-slots allowed by the deadline, such that the resulting error probability is minimized at the targeted receiver(s). The scheme differs from existing work in that it considers both unicast as well as broadcast and assumes that all nodes can overhear each other, as opposed to separating source nodes, relay nodes and destination nodes into three disjoint sets. A full analysis of the resulting error probability is provided and complementary numerical results show that the proposed relay sequencing strategy significantly improves reliability given a certain maximum delay, or alternatively, reduces the delay, given a certain target reliability requirement. To illustrate the performance improvements of relay sequencing, it is incorporated in a platooning application. If the decision regarding which relayer to assign in each time-slot can be taken online, just before the transmission, much can be gained. To this end, a low-complexity algorithm is developed, which is shown to be highly likely to find the optimal combination of relaying nodes that minimizes the resulting error probability at the targeted receiver(s). Data packets in wireless automation networks is typically small. To enable timely and reliable all-to-all broadcast in such systems, relay sequencing using packet aggregation is proposed. The strategy assigns relayers to time slots, as well as determines which packets to aggregate in each slot, using the proposed low-complexity algorithm. To further increase the reliability, a clustering scheme is proposed. When a relayer in the sequence fails to overhear a correct copy, a backup relayer in the cluster takes over. This work thereby enables ultra-reliable communications with maintained end-toend delay using low-complexity techniques and off-the-shelf components.
|
|
| 5. |
- Jonsson, Magnus, 1973-
(författare)
-
Thermally Expandable Microspheres Prepared via Suspension Polymerization - Synthesis, Characterization, and Application
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Thermally expandable microspheres are polymeric core/shell particles in which a volatile hydrocarbon is encapsulated by a thermoplastic shell. When these microspheres are heated, they expand and increase their volume dramatically. This volume increase is retained upon cooling, leading to a density reduction from around 1100 kg m-3 to about 30 kg m-3. Since the development in the early 1970´s, microspheres have been used extensively by the industry as a foaming agent or light weight filler. In this thesis, microspheres with a poly(acrylonitrile-co-methacrylonitrile) shell have been synthesized through free radical suspension polymerization. The microspheres have been characterized with respect to particle morphology and expansion properties in order to deepen the understanding of the microspheres. It was found that the monomer feed ratio and the polymerization temperature are very important parameters with respect to the expansion properties. Excellent expansion could only be accomplished when polymerizing at 62 °C, with the acrylonitrile feed, fAN, being around 60 mol%, even though core/shell microspheres are formed over a much wider range of fAN. Furthermore, no expansion was achieved when polymerizing at 80 °C, even though no noticeable differences were found, compared to the corresponding sample polymerized at 62 °C. It was also shown that the expansion properties can be modified by replacing the encapsulated hydrocarbon by another hydrocarbon with a different boiling point. Not only is the boiling point important, the structure of the hydrocarbon is also important. Isooctane which is highly branched was found to give superior expansion compared to linear or cyclic hydrocarbons having a similar boiling point. Crosslinking of the polymer shell has proven to be very important for the expansion properties. Both the amount and the structure of the crosslinker are important parameters. Especially the maximum expansion can be improved by the crosslinking of the polymer shell. This originates in an increase in the shape persistence of the expanded microspheres at elevated temperatures. By the combination of crosslinkers that are incorporated separately into the polymer shell, the onset temperature of expansion can be increased significantly. Finally, the surface of microspheres has been modified by grafting poly(glycidyl methacrylate) from the surface by ARGET ATRP. Given that the reaction conditions are appropriate, such modifications can be performed with only limited effects on the expansion properties of the microspheres.
|
|
| 6. |
- Kilger, Magnus, 1974-
(författare)
-
Talking talent : Narratives of youth sports selection
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In sports, there seems to be an eternal interest in discovering young talents and refining them into elite adult athletes. The dilemma of selecting talent, while at the same time ensuring every child´s right to participate, needs to be addressed and have consequences in social practice. This dissertation elucidates the discourse of selection and the process of selecting young sporting talents during final selection camps for youth national teams in football, hockey and floorball in Sweden. More specifically, the aim is to analyze how talent selection is organizationally legitimized, how “selectability” is produced in interaction and how specific narratives are used in success-stories. The empirical material includes research interviews, performance appraisal interviews (between district or national team coaches and the player) and field studies during ongoing final selection camp. Drawing on a discursive-narrative approach, the aim is to investigate how selection is discursively legitimized and, by using narrative analysis, how positioning in talk-in-interaction functions.The first article investigates the construction of legitimate selection within the Swedish Sports Confederation by analyzing their organizational documents, sport journals and literature for coach education. The findings show how a specific set of narratives are used to legitimize selection and how legitimacy works both individually to those within the selection system and on a wider arena of welfare politics. The second article investigates the co-construction of selectability in small story-interaction during interviews between the coach and a player in the final selection camp. The analyses highlight how this narrative genre produces certain stories and preferred positions. The third article analyzes how the young participants, in research interviews during final selection camp, uses discursively shared narratives to produce personal stories of success. The findings illustrate how the personal stories of success are balancing the dilemmatic space, positioning yourself as outstanding and at the same time appear a humble team player.The principal contribution of this dissertation is to show how talent is organizationally legitimized and how selectability is produced in interaction, as well as illustrate how specific stories are used in stories of success. This work investigates the discursive framework for selection and how rationalities for talent selection are produced (and reproduced) and co-constructed in narrative interaction. In this apparatus of selection it takes more than physical talent to be chosen; it takes talking talent.
|
|
| 7. |
- Lyamin, Nikita, 1989-
(författare)
-
Performance evaluation of C-ACC/platooning under ITS-G5 communications
- 2016
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Intelligent Transport Systems (ITS) are aiming to provide innovative services related to different modes of transport and traffic management, and enable various users to be better informed and make safer, more coordinated and smarter use of transport networks. Cooperative-ITS (C-ITS) support connectivity between vehicles, vehicles and roadside infrastructure, traffic signals as well as with other road users. In order to enable vehicular communications European Telecommunication Standards Institute (ETSI) delivered ITS-G5 -- a of set of C-ITS standards. Considering the goals of C-ITS, inter-vehicle communications should be reliable and efficient.In this thesis we study the performance, efficiency, and dependability of ITS-G5 communications for Cooperative adaptive cruise control (C-ACC) and platooning C-ITS applications. We provide an overview of currently available and ongoing standardization targeting communications in C-ACC/platooning. We study the performance of ITS-G5 beaconing in a C-ACC/platooning scenario, where we show that its performance may deteriorate when implemented in cooperative driving applications due to the kinematic-dependent design of the message triggering mechanism. We explain in detail the cause of this phenomenon and test it for a wide range of parameters. Also, we study the influence of different available ITS-G5 legitimate setups on the C-ACC/platooning fuel efficiency and demonstrate that proper communication setup may enhance fuel savings. This thesis also proposes a jamming denial-of-service attack detection algorithm for platooning. The main advantage of our detector is its short learning phase that not exceed a second and low detection delay of a few hundreds of milliseconds. Under some assumptions, the proposed algorithm demonstrates the ability to detect certain types of attacks with average probability above 0.9.
|
|
| 8. |
- Oanh, Ho Ngoc Hoang, 1986-
(författare)
-
Regulation of the multi-functional protein YscU in assembly of the Yersinia type III secretion injectisome
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Yersinia pseudotuberculosis is a Gram-negative zoonotic pathogenic bacterium causing gastroenteritis in human and animals. It shares a conserved virulence plasmid encoding for a needle-like secretion machinery, or type III secretion system, which can be found in other pathogenic Gram-negative bacteria. The type III secretion system (T3SS) is a macromolecular assembly that enables pathogenic effector proteins (or Yersinia outer proteins, Yops) to be transported into eukaryotic host cells. This export machinery is assembled in a highly ordered stepwise mechanism. The activation of T3SS is also dependent on calcium concentration, temperature, and pH of the growth media as mimic factors for host cell’s contact. The T3SS-associated inner-membrane protein, YscU, of Yersinia is proposed to function as a substrate specificity switch protein and forms basal structure of T3SS. YscU has four α helical transmembrane domain and a soluble cytoplasmic domain YscUC which undergoes auto-proteolysis at a conserved N↑PTH motif. The auto-proteolysis process, which is required for the assembly of the injectisome and secretion of Yops, results in a 10-kDa C-terminal polypeptide fragment, denoted YscUCC and 6-kDa N-terminal fragment YscUCN. In this thesis, we showed that YscUC dissociation was important for Yops secretion and resulted in unfolded YscUCN and oligomeric YscUCC. By combination in vivo and in vitro methods, growth media conditions as calcium, temperature, and pH were indicated to control secretion by regulation of YscUC dissociation. The calcium-binding isotherm to YscUC was fit best with a one-site binding model resulting in Kd 800 µM, which is identical to calcium level that blocks secretion in vivo. YscU is also the key protein for the T3SS pH dependence, demonstrated by thermal unfolding profile and secondary structure of protein were altered between pH 7.4 and 6.0. In addition, bacterial inner membrane was proposed to assist the YscUCN folding, monitored by using lipid bilayer as a mimic environment in nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy. This binding is important for Yops secretion and YscUC is anchored to bacterial membrane upon dissociation. The other substrate specificity switch protein YscP has function as a “molecular ruler” controlling length of the secretion needle. Previous genetic experiments have suggested that YscP and YscU interact physically, when mutation at defined residues on yscU (suppressor mutants) rescued Yops secretion in null-yscP mutant. In this research, direct binding of YscU and YscP was proved as weak but important interaction with Kd 430 mM by application of NMR and the binding interface of YscP was centred on the last helix of YscUC. Furthermore, we found that the YscP interaction could inhibit YscU auto-proteolysis. Studying the dissociation kinetic of suppressor YscUC variants at temperature 30 and 37oC provides strong support to a model where YscU is a temperature sensor for T3SS and YscUC dissociation is required for Yops secretion. Interestingly, the NPTH motif is conserved through most of YscU family members, meaning that role of dissociation may be conserved also in other bacterial injectisomes. To this end, the dissociation of YscU can be used as a therapeutic target in drug discovery. We attempted to identify the small-molecules that can hinder YscU dissociation. The small compound methyl(5-methyl-2-phenyl-1,3-thiazolidin-4-yl)acetate was found to be able to inhibit dissociation and to crystalize full YscUC, which has never been successfully done before. Finally, we found that the inner-rod protein YscI is binding to YscUC with a 1:1 stoichiometry as shown with pull-down assays and isothermal titration calorimetry. Taken together we have made several discoveries that expand the functional palette of YscU and all these functions were shown to have biological relevance with Yops secretion levels. In light of the strong sequence conservation between T3SS utilizing pathogenic bacteria the findings are likely to be general characters.
|
|
| 9. |
- Ramazanali, Hawar, 1979-
(författare)
-
Managing Radio and Energy Resources in LTE-Based Military Training Networks
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The number of wireless connected devices are growing exponentially and the importance of this research area is growing as well to meet the known and looming challenges and expectations. The 5:th Generation telecommunications standard is partly embodied by the Machine-to-Machine (M2M) and Internet of Things (IoT) technologies and standards to handle a big part of these devices and connections. An example within the IoT paradigm is military training systems where each system can consist of thousands of battery operated mobile devices and their shifting requirements shall be fullled in an energy-aware manner to increase battery operating times.Military training radio networks enables realistic combat training. The services and features provided in commercial telecommunications networks are desirable in these often proprietary and task specic networks, increasing capabilities and functionalities. To facilitate the current and future R&D of LTE based networks for adoption in military training networks and services this doctoral thesis intends to provide the starting ground for the energy-aware LTE based wireless communications. The thesis first presents general solutions on how to meet traffic deadlines in wireless networks for large number of nodes, and then continues with solutions for energy-aware LTE-based communications for the User Equipments (UEs).The work builds on the problem formulation how to provide energy-aware resource handling for LTE-based military training networks from where three research questions are derived. From the research questions we derive different hypotheses and then test these within the investigated area to answer the research questions.The contributions of this work are within areas of resource handling and power saving for mobile devices. In the first area an admission control using deterministic analysis is proposed fullling traffic requirements for military training mobile nodes. This admission control is enhanced for multiple-channel base stations, and evaluated using mobile nodes with different heterogeneous traffic requirements. In the second part energy-awareness is in focus for LTE/LTE-A based networks. The main power saving method for LTE/LTE-A UEs, Discontinuous Reception (DRX) mechanism, is evaluated and models for DRX in Idle and Connected state are proposed including metrics for wake-up delay and power saving. Additionally a mean queuing delay analysis is proposed for a variant of the Connected state DRX. Using these models and metrics, practical design guidelines for tuning of DRX parameters are proposed, including optimization of DRX parameters for either minimizing delay or maximizing power saving.
|
|
| 10. |
- Ramazanali, Hawar, 1979-
(författare)
-
Resource handling for military training networks
- 2015
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Connected devices are increasing steadily and the number of devices will in soon future be so massive that they are impacting the next generation of wireless standards and are already being considered in them. Machine-to-Machine (M2M) communications and Internet of Things (IoT) sub fields of wireless communications have developed lately with their own research fields and forums. Military training systems are using radio networks of connected devices to provide realistic combat training with new trends of multimedia streaming and lower traffic latency requirements. To facilitate further development of the networks a research goal is formulated to target the improvement of the network in the desired direction. The research goal is to answer how to provide energy efficient wireless communications within the framework of the military training application, meeting requirements of delay, number of network nodes and power efficiency for mobile devices and is broken down to three separate research questions that are each targeted separately as below.We have developed an admission control with real-time analysis for a single-frequency base station for mobile nodes with real-time traffic. This scope has been extended to an admission control for a multichannel base station where we also proposed a method on how to maximize the number of mobile nodes, with different traffic requirements including multimedia traffic, in the network. Finally a probabilistic model has been proposed for the Discontinuous Reception (DRX) power saving mechanism for LTE/LTE-A in the 4:th Generation (4G) telecommunications standard. It was also shown how to meet traffic delays while maximizing the power saving factor in the mobile nodes.
|
|
