Nous nous intéressons à estimer la moyenne d'une variable aléatoire de loi à queue lourde. Nous adoptons une approche plus robuste que la moyenne empirique classique communément utilisée. L'objectif est de développer des inégalités de concentration de type sous-gaussien sur l'erreur d'estimation. En d'autres termes, nous cherchons à garantir une forte concentration sous une hypothèse plus faible que la bornitude : une variance finie. Deux estimateurs de la moyenne pour une loi à support réel sont invoqués et leurs résultats de concentration sont rappelés. Plusieurs adaptations en dimension supérieure sont envisagées. L'utilisation appropriée de ces estimateurs nous permet d'introduire une nouvelle technique de minimisation du risque empirique pour des variables aléatoires à queue lourde. Quelques applications de cette technique sont développées. Nous appuyons ces résultats sur des simulations sur des jeux de données simulées. Dans un troisième temps, nous étudions un problème d'estimation multivarié dans le cadre des U-statistiques où les estimateurs précédents offrent, là aussi, une généralisation naturelle d'estimateurs présents dans la littérature. / In this thesis, we are interested in estimating the mean of heavy-tailed random variables. We focus on a robust estimation of the mean approach as an alternative to the classical empirical mean estimation. The goal is to develop sub-Gaussian concentration inequalities for the estimating error. In other words, we seek strong concentration results usually obtained for bounded random variables, in the context where the bounded condition is replaced by a finite variance condition. Two existing estimators of the mean of a real-valued random variable are invoked and their concentration results are recalled. Several new higher dimension adaptations are discussed. Using those estimators, we introduce a new version of empirical risk minimization for heavy-tailed random variables. Some applications are developed. These results are illustrated by simulations on artificial data samples. Lastly, we study the multivariate case in the U-statistics context. A natural generalization of existing estimators is offered, once again, by previous estimators.

Thesis discusses about different ways of a communication between components of a distributed system. It describes a communication using a message exchange and at the same time talks about other alternatives. It adds details about various models of a message exchange, various message types and about various specifications as well. Commercial tools ActiveMQ, RabbitMQ and Kafka are presented. Special emphasis is placed on describing the way these tools exchange messages, scalability options and others. The web service is designed according to the described features. Its main purpose is management and monitoring of the tool by user choice and easy replacement of this tool with another one. Designed application is implemented using the Kotlin language for selected tool RabbitMQ. The implemented solution allows a simple exchange of messages through the REST api.

This work deals with the qualitative requirements on services in IP networks based on technology Ethernet. We describe basic methods for imposing quality control mechanisms on services within networks. We elaborate on the ways, in which packets can be handled, overload controlled and transfer speed in network elements limited. Attention is given also to the Network Layer and Link Layer. Based on concrete specifications of network devices in UTKO laboratory an experimental network was designed and constructed. Network consisting of routers and switches linked several servers with client stations. Various types of data transfers (VoIP, HTTP, FTP, video) were generated. Several techniques for handling packets with different priorities were verified and compared. We observed that, in situations when connections are under full load, implementation of QoS support in the network becomes very important. This observation was confirmed by measurements. We also measured the parameters of the system during simulations of various situations, such as overload of a connection due to unsolicited operations or failure of a connection between routers. In order to guarantee the quality of services it is necessary to create a domain, in which rules are consistently observed in all network elements.

Ziel der Bachelorarbeit ist die Umsetzung und Erprobung eines Konzeptes zur Vermeidung von Überlastsituationen in paketvermittlenden Netzwerken. Hierzu wird ein Schedulingalgorithmus mit lastabhängiger Adaption der Bedienrate entwickelt -- die Burst Shaping Queue. Dieser folgt dem Konzept der Bedienratenregulierung durch Verzögerung des Bedienzeitpunktes für Pakete. Die entwickelte Schedulingeigenschaft wird in die Klasse der Closed Loop Ansätze zur Überlaststeuerung eingeordnet und gegenüber Open Loop Ansätzen abgegrenzt. Zur Leistungsuntersuchung wurde der Algorithmus als Erweiterung des Netzwerksimulator ns2 umgesetzt. Verschiedene Testreihen belegen das gewünschte Verhalten der Implementierung. Die Testergebnisse werden im Hinblick auf die Verwendbarkeit des Ansatzes und zukünftige Entwicklungsmöglichkeiten analysiert und beurteilt. / The aim of this document is the analysis, implementation and test of a concept for congestion control in packet-switched networks. A new scheduling-algorithm for a queue with load-dependent adaption of the queues' serving rate is being developed - the Burst Shaping Queue. The algorithm follows the concept of serving-rate adaption by delaying packets. The developed scheduling-strategy is being classified as a closed loop approach for congestion control and is differentiated from open loop approaches. For determining the algorithm's performance and to supply a base for further studies the algorithm is implemented as an extention for the network simulator ns2. Different tests show the desired behavior of the algorithm's implementation. The analysis and evaluation of the tests' results focus mainly on usability and extensibility of this approach.

The purpose of this thesis was to find approaches solving major performance and scalability issues for Topic Maps-related data access and the merging process. Especially regarding the management of multiple, heterogeneous topic maps with different sizes and structures. Hence the scope of the research was mainly focused on the Maiana web application with its underlying MaJorToM and TMQL4J back-end.

The main goal of this project has been to investigate how a message queue can be used to handle error codes in log files more actively. The project has followed the Design Science Research Methodology for development and implementation of the solution. A model of the transaction system was developed and emulated in newly developed applications. Two experiments were performed, the first of which tested a longer run time with intervals between messages and the second a time measurement of how long it takes to send 20 000 messages. The first experiment showed that the message queue was able to handle all messages which gave a high throughput of 22.5 messages per second without any messages being lost. The implemented consumer application received all messages and successfully counted the number of error codes in the received data. The experiments that have been carried out have proven that a message queue can be implemented to handle error codes in log files more actively. The future work that can be performed may include an evaluation of the security of the system, comparisons of performance compared to other message queues, performing the experiments on more powerful computers and implementation of machine learning to classify the log data. / Målet med det här projektet har varit att undersöka hur en meddelandekö kan användas för att felhantera felkoder i loggfiler mer aktivt. Projektet har följt Design Science Research Methodology för utveckling och implementering av lösningen. En modell av transaktionssystemet togs fram och emulerades i nyutvecklade applikationer. Två experiment utfördes varav det första testade en längre körning med intervall mellan meddelanden och det andra en tidmätning för hur lång tid det tar att skicka 20 000 meddelanden. Det första experimentet visade att meddelandekön klarade av att hantera meddelanden som skickades över två timmar. Det andra experimentet visade att systemet tog 14 minuter och 45 sekunder att skicka och hantera alla meddelanden, vilket gav en hög genomströmning av 22.5 meddelanden per sekund utan att några meddelanden gick förlorade. Den implementerade mottagarapplikationen tog emot alla meddelanden och lyckades räkna upp antalet felkoder som presenterades i den inkomna datan. De experiment som har utförts har bevisat att en meddelandekö kan implementeras för att felhantera felkoder i loggfiler mer aktivt. De framtida arbeten som kan utföras omfattar en utvärdering av säkerheten av systemet, jämförelser av prestanda jämfört med andra meddelandeköer, utföra experimenten på kraftfullare datorer och en implementering av maskininlärning för att klassificera loggdatan.

It is not always that easy to accurately interpret a parking signs The driver is expected to keep track of what every road sign, direction, prohibition, and amendment means, both by themselves and in combination with each others In addition, the driver must also keep track of the time, date, if there is a holiday, week number, etcs This can make the driver unsure of the rules, or interpret the rules incorrectly, which can lead to hefty fnes or even a towed vehicles By developing a mobile application that can analyze a photograph of a parking sign and quickly give the driver the verdict, the interpretation process can be made easys The purpose of this study has been to examine available technology within image and text analysis and then develop a prototype of an Android application that can interpret a photograph of a parking sign and quickly give the correct verdict, with the help of said technologys The constructed prototype will be evaluated partly by user tests to evaluate the application’s usability, and partly by functionality tests to evaluate the accuracy of the analysis processs Based on the results from the tests, a conclusion was drawn that the application gave a very informative and clear verdict, which was correct most of the time, but ran into problems with certain signs and under more demanding environmental circumstancess The tests also showed that the interface was perceived as easy to understand and use, though less interaction needed from the user was desireds There is a great potential for future development of ParCam, where the focus will be on increasing the automation of the processs / Att tolka en parkeringsskylt korrekt är inte alltid så  enkelt. Föraren förväntas ha koll på vad alla vägmärken, anvisningar, förbud, och tillägg betyder, både för sig själva och i kombination med varandra. Dessutom måste föraren även ha koll på  tid, datum, ev. helgdag, veckonummer m.m. Detta kan leda till att föraren blir osäker på vad som gäller eller tolkar reglerna felaktigt, vilket kan leda till dryga böter och även bortbogserat fordon. Genom att utveckla en mobilapplikation som kan analysera ett fotografi av en parkeringsskylt och snabbt ge svar kan denna tolkningsprocess underlättas för föraren. Syftet med denna studie har varit att utforska befintliga teknologier inom bild- och textanalys och därefter konstruera en prototyp av en Android-app som med hjälp av denna teknologi samt användarens mobilkamera kunna tolka fotografier av en parkeringsskylt och snabbt ge en korrekt utvärdering. Den konstruerade prototypen kommer att utvärderas dels genom användartester för att testa applikationens användbarhet och dels genom analys av utdata för att mäta analysens träffsäkerhet. Från testerna drogs slutsatsen att applikationen gav ett väldigt tydligt och informativt svar där analysen var korrekt de allra flesta gångerna, men stötte på problem med vissa skyltar och under svårare miljöförhållanden. Testerna visade också att gränssnittet upplevdes lätt att använda, men skulle helst kräva mindre inblandning från användaren. Det finns stor utvecklingspotential för ParCam, där fokus kommer att läggas på utökad automatisering av processen.

This report compares the characteristics of push/pull load balancing techniques usedin the context of a logging system. The logging system is expected to handle a largevolume of events. The load balancing techniques are evaluated with focus onthroughput during high load. The testing scenarios includes the use of a traditionalload balancer (push-based) and the use of messaging queues (pull-based and indirectlycontext aware) in its place. The ultimate goal of the report is to determine the feasibilityof using a messaging queue rather than a traditional load balancer in a distributedlogging system. Tests were conducted measuring the throughput of multiple setupswith different load balancers. The conclusion of this report is that both messagingqueues and load balancing are equally feasible in a logging context. / Rapporten jämför egenskaper hos lastbalanseringstekniker för användning i ettdistribuerat logghanteringssystem. Systemet förväntas hantera stora volymermeddelanden vid hög belastning. Testscenarion som utförs sker med traditionelllastbalansering där event trycks ut, samt med meddelandeköer som är hämtbaserade.Målet med rapporten är att avgöra om kontextbaserad lastbalansering kan ökastabiliteten i ett system avsett för hantering av loggdata. Testerna som utfördesuppmätte mängden data som gick igenom systemet vid en given tidpunkt, testernakördes med flera typer av lastbalanserare. Slutsatsen som dras är att bådemeddelandeköer och lastbalansering är passande för användning i ett loggsystem.

This research first identifies some of the key concerns about the techniques and algorithms developed for distributed and parallel model checking; specifically, the inherent problem with load balancing and large queue sizes resultant in a static partition algorithm. This research then presents a load balancing algorithm to improve the run time performance in distributed model checking, reduce maximum queue size, and reduce the number of states expanded before error discovery. The load balancing algorithm is based on Generalized Dimension Exchange (GDE). This research presents an empirical analysis of the GDE based load balancing algorithm on three different supercomputing architectures---distributed memory clusters, Networks of Workstations (NOW) and shared memory machines. The analysis shows increased speedup, lower maximum queue sizes and fewer total states explored before error discovery on each of the architectures. Finally, this research presents a study of the communication overhead incurred by using the load balancing algorithm, which although significant, does not offset performance gains.

This project is dedicated to modelling and optimization of a queue system and personnel management in organizations and is designed as a case study of a phone customer service. Customer services have become an important part of the majority of modern business systems thanks to its role as a primary tool for communication between companies and customers. Hence follows great academical and practical interest for splendidly designed customer systems and even for personnel welfare. The latter is an important factor influencing a number of aspects, for example system’s effectiveness, quality of service and personnel turnover. The theory behind queue modelling and simulations can be found in chapter 2, which is followed by data overview. The approach of modeling is described in chapter 4 and includes data processing, estimation of intensities and simulation of similar datasets based on the produced intensities. Simulations are also used to produce working timetables, to show the dependence between target achievements and budget and check the model’s accuracy. The optimal working timetable with different budget targets is presented at the end of the chapter 5. The model’s accuracy and implications of the case study are discussed in chapter 6. Chapter 7 is dedicated to personnel welfare. Firstly, we consider relevant theoretical background such as organization theory and its HR perspective. Overview of personnel welfare system of the customer service modelled in the mathematical part is given in 7.3.1. This part is followed by case study of a company called T-Mobile. After that some aspects of personnel welfare are discussed, and the conclusions are drawn in chapter 8. / Detta projekt behandlar modellering och optimering av ett kösystem samt personalvård på organisationer och är utformad som en fallstudie av en telefonkundtjänst. Kundtjänstsystem har blivit en viktig del av de flesta, om inte alla, moderna affärssystem tack vare dess roll som ett primärt kommunikationsinstrument för företag och kunder. Härav följer stort akademiskt och praktiskt intresse för välfungerande kundtjänstsystem och inte minst för personalvården. Det sistnämnda är en viktig faktor som påverkar en rad aspekter såsom kundtjänstsystemets effektivitet, servicekvalitet och personalomsättning. Teorin bakom kömodellering och simulering hittas i kapitel 2, som följs av dataöverblick i nästa kapitel. Tillvägagångssättet vid kömodelleringen beskrivs i kapitel 4 och inkluderar databearbetning, estimering av intensiteter samt simulering av liknande datamängder med de framtagna intensiteterna som utgångspunkter. Simuleringar används dessutom för att ta fram scheman, visa beroendet mellan variabler måluppfyllnad och budget och kontrollera modellens träffsäkerhet. Optimalt arbetsschema för olika budgetmålsättningar ställs upp och presenteras i slutet på kapitel 5. Modellens träffsäkerhet och implikationer av studiens resultat diskuteras i kapitel 6. Kapitel 7 är dedikerad till personalvård. Först vänder vi oss till teoretiska grunder av organisationsteori och dess HR-perspektiv. Översikt på hur personalvård ser ut på en kundtjänstavdelning vars kösystem har modellerats ges i 7.3.1. Den delen följs av fallstudien av ett bolag T-Mobile. Sedan markeras olika moment av personalvård i diskussionsdelen. Slutsatser sammanfattas i kapitel 8.