7 resultados para clustering and QoS-aware routing

em Dalarna University College Electronic Archive


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During the last decade, the Internet usage has been growing at an enormous rate which has beenaccompanied by the developments of network applications (e.g., video conference, audio/videostreaming, E-learning, E-Commerce and real-time applications) and allows several types ofinformation including data, voice, picture and media streaming. While end-users are demandingvery high quality of service (QoS) from their service providers, network undergoes a complex trafficwhich leads the transmission bottlenecks. Considerable effort has been made to study thecharacteristics and the behavior of the Internet. Simulation modeling of computer networkcongestion is a profitable and effective technique which fulfills the requirements to evaluate theperformance and QoS of networks. To simulate a single congested link, simulation is run with asingle load generator while for a larger simulation with complex traffic, where the nodes are spreadacross different geographical locations generating distributed artificial loads is indispensable. Onesolution is to elaborate a load generation system based on master/slave architecture.

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Personalized communication is when the marketing message is adapted to each individual by using information from a databaseand utilizing it in the various, different media channels available today. That gives the marketer the possibility to create a campaign that cuts through today’s clutter of marketing messages and gets the recipients attention. PODi is a non-profit organization that was started with the aim of contributing knowledge in the field of digital printingtechnologies. They have created a database of case studies showing companies that have successfully implemented personalizedcommunication in their marketing campaigns. The purpose of the project was therefore to analyze PODi case studies with the main objective of finding out if/how successfully the PODi-cases have been and what made them so successful. To collect the data found in the PODi cases the authors did a content analysis with a sample size of 140 PODi cases from the year 2008 to 2010. The study was carried out by analyzing the cases' measurable ways of success: response rate, conversion rate, visited PURL (personalized URL:s) and ROI (Return On Investment). In order to find out if there were any relationships to be found between the measurable result and what type of industry, campaign objective and media vehicle that was used in the campaign, the authors put up different research uestions to explore that. After clustering and merging the collected data the results were found to be quite spread but shows that the averages of response rates, visited PURL and conversion rates were consistently very high. In the study the authors also collected and summarized what the companies themselves claim to be the reasons for success with their marketing campaigns. The resultshows that the creation of a personalized campaign is complex and dependent on many different variables. It is for instance ofgreat importance to have a well thought-out plan with the campaign and to have good data and insights about the customer in order to perform creative personalization. It is also important to make it easy for the recipient to reply, to use several media vehicles for multiple touch points and to have an attractive and clever design.

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GPS tracking of mobile objects provides spatial and temporal data for a broad range of applications including traffic management and control, transportation routing and planning. Previous transport research has focused on GPS tracking data as an appealing alternative to travel diaries. Moreover, the GPS based data are gradually becoming a cornerstone for real-time traffic management. Tracking data of vehicles from GPS devices are however susceptible to measurement errors – a neglected issue in transport research. By conducting a randomized experiment, we assess the reliability of GPS based traffic data on geographical position, velocity, and altitude for three types of vehicles; bike, car, and bus. We find the geographical positioning reliable, but with an error greater than postulated by the manufacturer and a non-negligible risk for aberrant positioning. Velocity is slightly underestimated, whereas altitude measurements are unreliable.

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Bakgrund Dagligvaruhandel på internet växer och efterfrågas från fler kunder än någonsin tidigare. De större aktörerna märker att efterfrågan finns och inser att de behöver utöka sina försäljningskanaler, samtidigt som de mindre företagen som varit med och bidragit till denna efterfrågan behöver arbeta för att hålla sina kunder lojala och inte förlora marknadsandelar när marknadssituationen förändras av de stora aktörerna. Den förändrade konkurrenssituationen innebär att företag behöver lägga större fokus på kunden genom strategi och framförallt uppbyggnaden av lojalitet. Syfte Syftet är att få en ökad kunskap om hur ett företag som var tidigt ute på en marknad håller sina kunder lojala i samband med att konkurrenssituationen förändras. Metod För att besvara syftet har en kvalitativ fallstudie om företaget MatHem gjorts, för att slutligen kunna dra en generaliserad slutsats. Där insamling av primärdata och sekundärdata har analyserats för att slutligen nå en slutsats. Slutsats Det undersökta företaget håller sina kunder lojala genom att ha en hög generell kvalitet. Vilket betyder att de har hög kvalitet på produkterna, väl fungerande kundservice, överträffar kundens förväntningar och ett brett sortiment. När konkurrenssituationen förändras har företaget inga speciella strategier för att hålla sina kunder lojala, eftersom att företaget inte ser de andra aktörerna som konkurrenter. Företaget är den dyraste aktören på marknaden, men differentierar sig med ekologiska produkter för att erhålla lojala kunder.

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In the light of the twofold mission of Swedish schools, that is to say enabling pupils to develop both subject knowledge and a democratic attitude, the purpose of this thesis is to investigate to what extent adult higher education students from different language and social backgrounds, studying Swedish as a second language, are able to carry out joint writing assignments with the aid of deliberative discourse, and to what extent they thereby also develop a deliberative attitude. The twofold mission of education applies to them too. While there already exists a certain amount of research into deliberative discourse relating to education in schools, the perspective of higher education didactics in this research is still lacking. The present study is to be viewed as a first contribution to this research. The theoretical starting point of this study includes previous research into deliberative discourse by further developing an existing model regarding criteria for deliberative discourse, for example that there is a striving towards agreement, although the consensus may be temporary, that diverging opinions can be set against each other, that tolerance and respect for views other than one’s own are shown, and that traditional outlooks can be questioned. This model is supplemented by designations for a number of disruptive behaviours, such as ridiculing, ignoring, interrupting people and engaging in private conversations. The thus further developed model will thereafter act as a lens in the analysis of students’ discussions when writing joint texts. Another theoretical starting point is the view of education as communication, and of the possibility of communication creating a third place, thereby developing democracy in the here and now-situation. For this study, comprising 18 hours of observation of nine students, that is to say the discussions of three groups in connection with writing texts on different occasions, various ethnographic data collection methods have been employed, for example video recordings, participant observations, field notes and interviews in conjunction with the discussions. The analysis clarifies that the three groups developed their deliberation as the discussions about the joint assignment proceeded, and that most of the nine students furthermore expressed at least an openness towards a deliberative attitude for further discussions in the future. The disruptive behaviours mentioned in connection with the analytical model that could be identified in the discussions, for example interruptions and private conversations, proved not to constitute real disturbances; on the contrary they actually contributed towards the discussions developing, enabling them to continue. On the other hand, other and not previously identified disturbances occurred, for example a focus on grades, the lack of time and lacking language ability, which all in different ways affected the students’ attitudes towards their work. For any future didactical work on deliberative discourse in Swedish as a second language within higher education, these disturbances would need to be highlighted and made aware of for both teachers and students. Keywords: higher education didactics, communication, deliberative discourse, deliberative attitude, John Dewey, Tomas Englund, heterogeneity, ethnographic data collection methods.

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This Thesis Work will concentrate on a very interesting problem, the Vehicle Routing Problem (VRP). In this problem, customers or cities have to be visited and packages have to be transported to each of them, starting from a basis point on the map. The goal is to solve the transportation problem, to be able to deliver the packages-on time for the customers,-enough package for each Customer,-using the available resources- and – of course - to be so effective as it is possible.Although this problem seems to be very easy to solve with a small number of cities or customers, it is not. In this problem the algorithm have to face with several constraints, for example opening hours, package delivery times, truck capacities, etc. This makes this problem a so called Multi Constraint Optimization Problem (MCOP). What’s more, this problem is intractable with current amount of computational power which is available for most of us. As the number of customers grow, the calculations to be done grows exponential fast, because all constraints have to be solved for each customers and it should not be forgotten that the goal is to find a solution, what is best enough, before the time for the calculation is up. This problem is introduced in the first chapter: form its basics, the Traveling Salesman Problem, using some theoretical and mathematical background it is shown, why is it so hard to optimize this problem, and although it is so hard, and there is no best algorithm known for huge number of customers, why is it a worth to deal with it. Just think about a huge transportation company with ten thousands of trucks, millions of customers: how much money could be saved if we would know the optimal path for all our packages.Although there is no best algorithm is known for this kind of optimization problems, we are trying to give an acceptable solution for it in the second and third chapter, where two algorithms are described: the Genetic Algorithm and the Simulated Annealing. Both of them are based on obtaining the processes of nature and material science. These algorithms will hardly ever be able to find the best solution for the problem, but they are able to give a very good solution in special cases within acceptable calculation time.In these chapters (2nd and 3rd) the Genetic Algorithm and Simulated Annealing is described in details, from their basis in the “real world” through their terminology and finally the basic implementation of them. The work will put a stress on the limits of these algorithms, their advantages and disadvantages, and also the comparison of them to each other.Finally, after all of these theories are shown, a simulation will be executed on an artificial environment of the VRP, with both Simulated Annealing and Genetic Algorithm. They will both solve the same problem in the same environment and are going to be compared to each other. The environment and the implementation are also described here, so as the test results obtained.Finally the possible improvements of these algorithms are discussed, and the work will try to answer the “big” question, “Which algorithm is better?”, if this question even exists.

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IPTV is now offered by several operators in Europe, US and Asia using broadcast video over private IP networks that are isolated from Internet. IPTV services rely ontransmission of live (real-time) video and/or stored video. Video on Demand (VoD)and Time-shifted TV are implemented by IP unicast and Broadcast TV (BTV) and Near video on demand are implemented by IP multicast. IPTV services require QoS guarantees and can tolerate no more than 10-6 packet loss probability, 200 ms delay, and 50 ms jitter. Low delay is essential for satisfactory trick mode performance(pause, resume,fast forward) for VoD, and fast channel change time for BTV. Internet Traffic Engineering (TE) is defined in RFC 3272 and involves both capacity management and traffic management. Capacity management includes capacityplanning, routing control, and resource management. Traffic management includes (1)nodal traffic control functions such as traffic conditioning, queue management, scheduling, and (2) other functions that regulate traffic flow through the network orthat arbitrate access to network resources. An IPTV network architecture includes multiple networks (core network, metronetwork, access network and home network) that connects devices (super head-end, video hub office, video serving office, home gateway, set-top box). Each IP router in the core and metro networks implements some queueing and packet scheduling mechanism at the output link controller. Popular schedulers in IP networks include Priority Queueing (PQ), Class-Based Weighted Fair Queueing (CBWFQ), and Low Latency Queueing (LLQ) which combines PQ and CBWFQ.The thesis analyzes several Packet Scheduling algorithms that can optimize the tradeoff between system capacity and end user performance for the traffic classes. Before in the simulator FIFO,PQ,GPS queueing methods were implemented inside. This thesis aims to implement the LLQ scheduler inside the simulator and to evaluate the performance of these packet schedulers. The simulator is provided by ErnstNordström and Simulator was built in Visual C++ 2008 environmentand tested and analyzed in MatLab 7.0 under windows VISTA.