The mobile ad hoc network (MANET) has become a popular technology in recent years. Due to most devices are battery powered, energy conservation is a critical issue in the MANET. To save energy and extend battery life, nodes should turn their radios off when they have no packet to send or receive. To achieve this, IEEE 802.11 defined a synchronous power saving mechanism (PSM) based on periodical beacon transmission. It allows devices to turn their radios off when no data has to be sent or received. However, the idle state is long because the device must remain awake during the entire beacon interval even though there is only a small amount of data packets to be sent. Although some PSMs have been proposed, they still suffer from a long idle state. In this paper, we propose a new power saving mechanism by dynamically adjusting the sleeping time based on the network traffic. Simulation results show that the proposed PSM outperforms other PSMs in energy goodput and lifetime.

This thesis explores the design of flexible pipes, buried in shallow trenches with dry sand backfill. The thesis reports the comprehensive analysis of twenty-two full-scale load tests conducted between 1989 and 1991 on pipe installations, mainly within a laboratory facility, at the University of South Australia. The pipes were highly flexible, spirally-wound, uPVC pipes, ranging in diameter from 300 to 450 mm. Guidelines were required by industry for safe cover heights for these pipes when subjected to construction traffic. The tests were designed by, and conducted under the supervision of, the author, prior to the author undertaking this thesis. As current design approaches for pipes could not anticipate the large loading settlements and hence, soil plasticity, experienced in these tests, finite element analyses were attempted. Extensive investigations of the materials in the installations were undertaken to permit finite element modelling of the buried pipe installations. In particular, a series of large strain triaxial tests were conducted on the sand backfill in the buried pipe installations, to provide an understanding of the sand behaviour in terms of critical state theory. Subsequently a constitutive model for the soil was developed. The soil model was validated before implementation in an element of finite element program, AFENA (Carter and Balaam, 1995). Single element modelling of the triaxial tests proved invaluable in obtaining material constants for the soil model. The new element was applied successfully to the analysis of a side-constrained, plate loading test on the sand. The simulation of the buried pipe tests was shown to require three-dimensional finite element analysis to approach the observed pipe-soil behaviour. Non-compliant side boundary conditions were ultimately adjudged chiefly responsible for the difficulty in matching the experimental data. The value of numerical analyses performed in tandem with physical testing was apparent, albeit in hindsight. The research has identified the prediction of vertical soil pressure above the pipe due to external loading as being the major difficulty for designers. Based on the finite element analyses of the field tests, a preliminary simple expression was developed for estimation of these pressures, which could be used with currently available design approaches to reasonably predict pipe deflections.

Research in the area of bridge design has been and still isconcentrated on the study of the strength of materials andrelatively few studies have been performed on traffic loads andtheir effects. Traffic loads have usually been assumed to begiven in codes. This is mainly because it is very difficult tomodel traffic loads in an accurate manner because of theirrandomness. In this work, statistical evaluations of traffic loadeffects, obtained from real as well as Monte Carlo (MC)simulated vehicle data, are presented. As the dynamiccontribution of the vehicle load was filtered by the systemused for measuring vehicle weight, no attention was paid in thepresent study to the dynamic effects or the impact factor. Thedynamic contribution of the traffic load models from codes wasdeducted wherever they were compared with the result from theevaluation of the real data. First, the accuracy of thecollected data was investigated. This was done to examine theinfluence of what was most probably unreasonable data on thefinal evaluated results. Subsequently, the MC simulationtechnique, using a limited amount of the collected data, wasused to generate fictitious vehicle data that could representresults from field measurements which would otherwise have tobe recorded under a long period. Afterwards, the characteristictotal traffic loads for bridges with large spans weredetermined by probabilistic analysis. This was done using realas well as simulated data and the two were compared. Theseresults were also compared with the corresponding valuescalculated using the traffic load model from the Swedish bridgedesign code. Furthermore, using traffic data, different load effects onbridges (girder distribution factor of slab-on-girder bridgesand the mid-span deflection as well as the longitudinal stressat critical locations on box-girder bridges) were investigated.The main task was to obtain a more accurate knowledge oftraffic load distributions on bridges as well as their effectsfor infrastructure design. The results showed that the trafficload models from codes gave considerably higher load effectscompared to the current actual traffic load effects. Theseinvestigations were based on the available data for the actualposition of the vehicles on a single bridge and might not coverall possible traffic scenarios. The results showed only how thereal traffic loads, under”normal”conditions andtheir transverse positions relate to the load model accordingto the codes. <b>KEYWORDS:</b>bridge, traffic load, load effect, transversedistribution, characteristic value,weigh in motion, MonteCarlo simulation, Rice’s formula, level crossinghistogram, vehicle queue.

<p>Research in the area of bridge design has been and still isconcentrated on the study of the strength of materials andrelatively few studies have been performed on traffic loads andtheir effects. Traffic loads have usually been assumed to begiven in codes. This is mainly because it is very difficult tomodel traffic loads in an accurate manner because of theirrandomness.</p><p>In this work, statistical evaluations of traffic loadeffects, obtained from real as well as Monte Carlo (MC)simulated vehicle data, are presented. As the dynamiccontribution of the vehicle load was filtered by the systemused for measuring vehicle weight, no attention was paid in thepresent study to the dynamic effects or the impact factor. Thedynamic contribution of the traffic load models from codes wasdeducted wherever they were compared with the result from theevaluation of the real data. First, the accuracy of thecollected data was investigated. This was done to examine theinfluence of what was most probably unreasonable data on thefinal evaluated results. Subsequently, the MC simulationtechnique, using a limited amount of the collected data, wasused to generate fictitious vehicle data that could representresults from field measurements which would otherwise have tobe recorded under a long period. Afterwards, the characteristictotal traffic loads for bridges with large spans weredetermined by probabilistic analysis. This was done using realas well as simulated data and the two were compared. Theseresults were also compared with the corresponding valuescalculated using the traffic load model from the Swedish bridgedesign code.</p><p>Furthermore, using traffic data, different load effects onbridges (girder distribution factor of slab-on-girder bridgesand the mid-span deflection as well as the longitudinal stressat critical locations on box-girder bridges) were investigated.The main task was to obtain a more accurate knowledge oftraffic load distributions on bridges as well as their effectsfor infrastructure design. The results showed that the trafficload models from codes gave considerably higher load effectscompared to the current actual traffic load effects. Theseinvestigations were based on the available data for the actualposition of the vehicles on a single bridge and might not coverall possible traffic scenarios. The results showed only how thereal traffic loads, under”normal”conditions andtheir transverse positions relate to the load model accordingto the codes.</p><p><b>KEYWORDS:</b>bridge, traffic load, load effect, transversedistribution, characteristic value,weigh in motion, MonteCarlo simulation, Rice’s formula, level crossinghistogram, vehicle queue.</p>

This thesis explores the design of flexible pipes, buried in shallow trenches with dry sand backfill. The thesis reports the comprehensive analysis of twenty-two full-scale load tests conducted between 1989 and 1991 on pipe installations, mainly within a laboratory facility, at the University of South Australia. The pipes were highly flexible, spirally-wound, uPVC pipes, ranging in diameter from 300 to 450 mm. Guidelines were required by industry for safe cover heights for these pipes when subjected to construction traffic. The tests were designed by, and conducted under the supervision of, the author, prior to the author undertaking this thesis. As current design approaches for pipes could not anticipate the large loading settlements and hence, soil plasticity, experienced in these tests, finite element analyses were attempted. Extensive investigations of the materials in the installations were undertaken to permit finite element modelling of the buried pipe installations. In particular, a series of large strain triaxial tests were conducted on the sand backfill in the buried pipe installations, to provide an understanding of the sand behaviour in terms of critical state theory. Subsequently a constitutive model for the soil was developed. The soil model was validated before implementation in an element of finite element program, AFENA (Carter and Balaam, 1995). Single element modelling of the triaxial tests proved invaluable in obtaining material constants for the soil model. The new element was applied successfully to the analysis of a side-constrained, plate loading test on the sand. The simulation of the buried pipe tests was shown to require three-dimensional finite element analysis to approach the observed pipe-soil behaviour. Non-compliant side boundary conditions were ultimately adjudged chiefly responsible for the difficulty in matching the experimental data. The value of numerical analyses performed in tandem with physical testing was apparent, albeit in hindsight. The research has identified the prediction of vertical soil pressure above the pipe due to external loading as being the major difficulty for designers. Based on the finite element analyses of the field tests, a preliminary simple expression was developed for estimation of these pressures, which could be used with currently available design approaches to reasonably predict pipe deflections.

Wide area cellular mobile networks have rapidly evolved over the years. In the beginning achieving wide area coverage was a great achievement – enabling subscribers to call from wherever they were currently located and whenever they wanted. Additionally these systems supported mobility of subscribers, so that calls could continue even while a subscriber moved from one cell to another. Today mobility management is something everyone takes for granted. New functionality is continuously being developed for these networks. An important aspect of this evolution has been to enable new applications and technologies to be introduced while maintaining interoperability with the existing technologies. These mobile networks use new technologies and enable new applications, but they interconnect with existing networks that utilize earlier technologies, such as the existing fixed telephone network. These interconnections enable communication between subscribers connected via all of these networks. In today’s mobile networks there are a variety of technologies working side by side, for example 2G, GPRS, 3G, and so on. The earlier networks used circuit switching technology, but the trend in later networks was to transition exclusively to packet switching. One of the most important network entities is the mobile switch center (MSC). In the earlier circuit switched networks the MSC is the heart of the circuit switching network. The MSC is responsible for management, control, and communication to and from the mobile stations (MSs) in the area managed by the MSC. The MSC stores information about each of the MSs in one or more databases. In the subscriber’s home network the information about their subscription is stored in a home location register (HLR), while when this subscriber is in another network information is stored in a visitor location register (VLR). The MSC together with other elements of the core network handles mobility management, enabling both handover and roaming. A gateway MSC enables MSs to communicate with phones connected to the fixed network. The aim of this thesis is to analyze the traffic situation for Kulyab region in order to configure and install the MSC in Kulyab. For the time being there is no radio network controller (RNC) in Kulyab region, so the MSC in Kulyab will be configured to support 2G traffic. The configuration will be based on the expected mobile traffic load in the Kulyab region, thus the first steps in the process were to collect and analyze data about the existing traffic in this region that is currently served by a MSC located outside of this region. The configuration of the new MSC will be based on this analysis. After installing and configuring the new MSC some question need to be answered, namely: Can the MSC in Kulyab support all the base stations in Kulyab region? If not, how many base stations can it support? To what extent does the addition of this new MSC improve the overall network in terms of increased reliability, capacity, and throughput? How much will the capacity of the existing MSC, that is responsible for traffic outside Dushanbe, be increased due to the introduction of the new MSC? / Den mobila täckningen har utvecklats snabbt under åren. Att uppnå den mobila täckningen var i början en stor prestation – att kunna erbjuda telefontjänster för abonnenterna var än de befann sig och när de ville. Förutom detta så stödde detta system också fri rörlighet för abonnenterna. Under ett samtal kunde de förflytta sig från en cell till ett annan utan att samtalet bröts. Nu är mobilitetshanteringen någonting självklart. Nya funktioner utvecklas ständigt för dessa nätverk. En viktig aspekt för utvecklingen är att möjliggöra så att nya applikationer och teknologier kan introduceras och fortfarande vara kompatibla med de existerande teknikerna. Dessa mobilnätverk använder nya tekniker och möjliggör nya applikationer som är kompatibla med det existerande nätverket. Det existerande nätverket använder sig av tidigare teknologier, så som den fasta telefonnätet. Detta möjliggör kommunikation mellan abonnenterna från olika nätverk. I dagens nätverk finns det ett antal olika nätverk, som t.ex. 2G, GPRS, 3G och så vidare. Det tidigare nätverket använde sig av kretskopplad teknik, men trenden är attuteslutande använda sig av paketkopplad teknik. En av de viktigaste nätverksenheterna är ”Mobile switch center” (MSC). I de tidigare kretskopplade nätverket är MSC hjärtat i det kretskopplade nätverket. MSC är ansvarig för hanteringen, kontrollen och kommunikation till och från demobila enheterna (MS) i området som kontrolleras av MSCn. MSC lagrar information om var och en av MS i ett eller flera databaser. I abonnentens hemnätverk finns information om abonnentens abonnemang i ett hemregister (HLR). När abonnenten befinner sig i ett annat nätverk lagras informationen i ett gästregister (VLR). MSC hanterar mobilitet tillsammans med andra nätverksenheter i ”Core network” (CN) och möjliggör överlämnande (handover) och roaming. ”Gateway MSC” GMSC möjliggör kommunikation mellan MS och det fasta nätverket. Syftet med examensarbetet är att analysera trafiken för Kulyab-regionen för att konfigurera och installera en MSC i Kulyab. För tillfället finns ingen ”Radio network controller” (RNC) i regionen Kulyab, så MSCn i Kulyab kommer att konfigureras för att stödja 2G trafik. Konfigurationen baseras på den förväntade belastningen av mobiltrafiken i Kulyab-regionen, följaktligen är det första steget i processen att samla ihop och analysera information om den existerande trafiken i Kulyab-regionen. Trafiken tillhörande Kulyab-regionen handskas för närvarande av en MSC som befinner sig utanför detta område. Konfigurationen av den nya MSCn kommer att baseras på denna analys. Efter installationen och konfigurationen av den nya MSCn kommer följande frågor att bli besvarade, nämligen: Kan MSCn i Kulyab stödja alla basstationerna i Kulyab regionen? Om inte, hur många basstationer kan MSCn stödja? Till vilken grad kommer den nya MSCn att förbättra nätverket i termer av ökad tillförlitlighet, kapacitet och trafikgenomströmning? Hur mycket kommer kapacitetsökningen för den existerande MSC utanför Dushanbe att öka då MSC i Kulyab installeras?

L’application de jeu en ligne massivement multijoueurs fournit une grandepartie du trafic Internet global. Le trafic est généralement composé d’unepetite partie de données utiles encapsulé dans des segments TCP, entrainantun volume élevé d’entêtes transmis via le réseau. Cela implique: 1) la tailledes paquets est trop petite pour un routage efficace et; 2) la bande passanterequise par le serveur augmente. Par conséquent, il est nécessaire de trouverdes techniques de transmission et de routage plus efficaces afin de réduire levolume de trafic et augmenter l’efficacité du réseau permettant de prendre encharge le nombre croissant des joueurs. D’autre part, la qualité d’expérience(QoE) dans le contexte des jeux en ligne est fortement liée à la consistance.Cette consistance est influencée par la qualité de service (QoS) offerte parle réseau, principalement en termes de délai, de gigue et d’ordre de paquets.Par conséquent, une solution qui améliore ces paramètres aidera à satisfairedavantage de joueurs et à améliorer la qualité de service.L’objectif de cette thèse est de proposer des solutions pour améliorerla qualité d’expérience des jeux en ligne en augmentant la consistance devue, en réduisant les délais et en augmentant l’efficacité du réseau. Pour leproblème de consistance, nous proposons une topologie de réseau cyclique.Cette topologie ordonnée facilite la mise en place des procédures de gestionet de contrôle de la transmission pour imposer un ordre causal entre tousles joueurs. Concernant le délai et l’efficacité du réseau, certains ont proposé l’application de la technique du tunnel, compression et multiplexage(TCM). Cependant, les paquets transmis avec TCM sont plus grands queceux d’origine, ce qui nécessite plus de temps pour les transmettre et augmente le risque de saturation au niveau des fils d’attente. Nous proposonsl’utilisation de la technique de codage réseau (NC) qui permet d’augmenterle débit dans certaines conditions de topologies et de routage. Cette technique permet aux nœuds intermédiaires d’encoder les paquets qu’ils reçoivent plutôt que d’effectuer une simple fonction de stockage et de transfert. Celapeut réduire la charge de trafic, réduire les délais et augmenter l’efficacité duréseau.Dans cette thèse, nous proposons des modifications pour améliorer latechnique TCM et nous évaluons ses performances. De plus, nous proposonsd’ajouter le concept de partition des joueurs et de changer la topologie d’unarbre à une forêt. Nous étudions ensuite la topologie cyclique. Nous concevons un protocole de routage optimisé sur une topologie en cycle baséesur la technique de codage réseau. Puis, nous évaluons ses performances entermes de délai, de charge et d’ordre. Les résultats montrent que l’utilisationdu codage NC permet de réduire la charge et le nombre de paquets transmis, garantir un ordre de paquet par période et de réduire le délai. Eneffet, on peut gagner jusqu’à 14% de latence avec notre protocole par rapport à un protocole de routage optimisé sans codage réseau. Par la suite,nous proposons un scénario de mise en pratique de cette solution sur une infrastructure Device-to-Device. Nous validons les limites théoriques du délaien utilisant des simulations réseau et nous discutons ensuite des contraintespratiques qui s’imposent lors de l’implémentation dans un réseau réel. Finalement, nous proposons des solutions pour ces contraintes. / The application of massively multiplayer online games provides a large partof the global internet traffic. The traffic is typically encapsulated in TCPsegments of small size information (the so called payload) resulting in a highvolume of headers transmitted through the network. This implies the following: 1) the packets’ size is too small for efficient routing and; 2) thebandwidth required by the server seems to be increasing. Therefore, it isnecessary to find more efficient transmission and routing techniques to reduce the traffic’s volume and to increase the network’s efficiency in orderto support the growing number of players. On the other hand, Quality ofExperience (QoE) in the context of online games is strongly influenced byconsistency. This consistency is influenced by the quality of service (QoS) offered by the network, mainly in terms of delay, jitter and order of the packets.As a result, a solution that enhances these parameters will help in satisfyingmore players and subsequently improving QoE.The goal of this thesis is to propose solutions to enhance the QoE of onlinegames by increasing the consistency of view, reducing the delay and increasing the efficiency of the network. For consistency, we propose a cyclic networktopology. This ordered topology facilitates the implementation of transmission management and control procedures to impose a causal order betweenall players. As for the delay and the efficiency problem, some have proposed the application of Tunneling, Compression and Multiplexing (TCM)technique. However, the transmitted packets with TCM are larger than theoriginal ones, which requires more delay to transmit them and increases therisk of congestion. We propose the use of the Network Coding technique(NC) which makes it possible to increase the bit rate of the network undercertain topological and routing conditions. This technique allows intermediate nodes to encode the data they receive rather than perform a simple”store and forward” function. It can reduce the traffic load, reduce the delay and increase the network’s efficiency.In this thesis, we propose some modifications to enhance the TCM technique and evaluate its performance. Besides, we propose to add the playerspartition approach and change the topology from a tree to a forest. Afterwards, we investigate the cyclic topology. We design an optimized routingprotocol over a cycle topology based on the network coding technique andevaluate its performance in terms of delay and order. The results show thatby using NC coding, one can gain up to 14% of latency over an optimizedrouting protocol for the cycle topology without the use of network coding.Afterwards, we propose a practical implementation scenario of this solutionover a device-to-device (D2D) infrastructure. We finally validate the theoretical limits of delay using network simulations and discuss a number ofpractical constraints.

The work presented in this thesis studies the load and loadeffects of traffic loads on railway bridges. The increasedknowledge of the traffic loads, simulated using fieldmeasurements of actual trains, are employed in a reliabilityanalysis in an attempt at upgrading existing railwaybridges. The study utilises data from a weigh-in-motion site whichrecords, for each train, the train speed, the loads from eachaxle and the axle spacings. This data of actual trainconfigurations and axle loads are portrayed as moving forcesand then used in computer simulations of trains crossing twodimensional simply supported bridges at constant speed. Onlysingle track short to medium span bridges are considered in thethesis. The studied load effect is the moment at mid-span. Fromthe computer simulations the moment history at mid-span isobtained. The load effects are analysed by two methods, the first isthe classical extreme value theory where the load effect ismodelled by the family of distributions called the generalisedextreme value distribution (GEV). The other method adopts thepeaks-over-threshold method (POT) where the limiting family ofdistributions for the heights to peaks-over-threshold is theGeneralised Pareto Distribution (GPD). The two models aregenerally found to be a good representation of the data. The load effects modelled by either the GEV or the GPD arethen incorporated into a reliability analysis in order to studythe possibility of raising allowable axle loads on existingSwedish railway bridges. The results of the reliabilityanalysis show that they are sensitive to the estimation of theshape parameter of the GEV or the GPD. While the study is limited to the case of the ultimate limitstate where the effects of fatigue are not accounted for, thefindings show that for the studied cases an increase inallowable axle load to 25 tonnes would be acceptable even forbridges built to the standards of 1940 and designed to LoadModel A of that standard. Even an increase to both 27.5 and 30tonnes appears to be possible for certain cases. It is alsoobserved that the short span bridges ofapproximately fourmetres are the most susceptible to a proposed increase inpermissible axle load. <b>Keywords:</b>bridge, rail, traffic load, load effect,dynamic amplification factor, extreme value theory,peaks-over-threshold, reliability theory, axle loads, fielddata.

<p>The work presented in this thesis studies the load and loadeffects of traffic loads on railway bridges. The increasedknowledge of the traffic loads, simulated using fieldmeasurements of actual trains, are employed in a reliabilityanalysis in an attempt at upgrading existing railwaybridges.</p><p>The study utilises data from a weigh-in-motion site whichrecords, for each train, the train speed, the loads from eachaxle and the axle spacings. This data of actual trainconfigurations and axle loads are portrayed as moving forcesand then used in computer simulations of trains crossing twodimensional simply supported bridges at constant speed. Onlysingle track short to medium span bridges are considered in thethesis. The studied load effect is the moment at mid-span. Fromthe computer simulations the moment history at mid-span isobtained.</p><p>The load effects are analysed by two methods, the first isthe classical extreme value theory where the load effect ismodelled by the family of distributions called the generalisedextreme value distribution (GEV). The other method adopts thepeaks-over-threshold method (POT) where the limiting family ofdistributions for the heights to peaks-over-threshold is theGeneralised Pareto Distribution (GPD). The two models aregenerally found to be a good representation of the data.</p><p>The load effects modelled by either the GEV or the GPD arethen incorporated into a reliability analysis in order to studythe possibility of raising allowable axle loads on existingSwedish railway bridges. The results of the reliabilityanalysis show that they are sensitive to the estimation of theshape parameter of the GEV or the GPD.</p><p>While the study is limited to the case of the ultimate limitstate where the effects of fatigue are not accounted for, thefindings show that for the studied cases an increase inallowable axle load to 25 tonnes would be acceptable even forbridges built to the standards of 1940 and designed to LoadModel A of that standard. Even an increase to both 27.5 and 30tonnes appears to be possible for certain cases. It is alsoobserved that the short span bridges ofapproximately fourmetres are the most susceptible to a proposed increase inpermissible axle load.</p><p><b>Keywords:</b>bridge, rail, traffic load, load effect,dynamic amplification factor, extreme value theory,peaks-over-threshold, reliability theory, axle loads, fielddata.</p>

No description available.