To deliver a reliable communication service over the Internet it is essential for the network operator to manage the traffic situation in the network. The traffic situation is controlled by the routing function which determines what path traffic follows from source to destination.  Current practices for setting routing parameters in IP networks are designed to be simple to manage. This can lead to congestion in parts of the network while other parts of the network are far from fully utilized. In this thesis we explore issues related to optimization of the routing function to balance load in the network and efficiently deliver a reliable communication service to the users. The optimization takes into account not only the traffic situation under normal operational conditions, but also traffic situations that appear under a wide variety of circumstances deviating from the nominal case. In order to balance load in the network knowledge of the traffic situations is needed. Consequently, in this thesis we investigate methods for efficient derivation of the traffic situation. The derivation is based on estimation of traffic demands from link load measurements. The advantage of using link load measurements is that they are easily obtained and consist  of a limited amount of data that need to be processed. We evaluate and demonstrate how estimation based on link counts gives the operator a fast and accurate description of the traffic demands. For the evaluation we have access to a unique data set of complete traffic demands from an operational IP backbone.  However, to honor service level agreements at all times the variability of the traffic needs to be accounted for in the load balancing. In addition, optimization techniques are often sensitive to errors and variations in input data. Hence, when an optimized routing setting is subjected to real traffic demands in the network, performance often deviate from what can be anticipated from the optimization. Thus, we identify and model different traffic uncertainties and describe how the routing setting can be optimized, not only for a nominal case, but for a wide range of different traffic situations that might appear in the network.  Our results can be applied in MPLS enabled networks as well as in networks using link state routing protocols such as the widely used OSPF and IS-IS protocols. Only minor changes may be needed in current networks to implement our algorithms. The contributions of this thesis is that we: demonstrate that it is possible to estimate the traffic matrix with acceptable precision, and we develop methods and models for common traffic uncertainties to account for these uncertainties in the optimization of the routing configuration. In addition, we identify important properties in the structure of the traffic to successfully balance uncertain and varying traffic demands. / QC 20110211

The aim of the thesis is to develop and describe WRAP’s capabilities in handling the WiMAX standard as defined in IEEE 802.16e related to traffic capacity calculations. WRAP International has developed the software WRAP for spectrum management and radio network planning. WRAP includes various technical calculation functions that are applied for design and analysis tasks with the purpose of achieving the desired quality of service within radio communication networks, navigation and radar systems. WRAP already includes functions for radio wave calculations to establish for instance coverage; best server maps etc, as well as traffic calculations for cellular networks (2G) using channel-orientated calculations that are modeled by Erlang B and Erlang C formulas. Since WiMAX supports multiple broadband data services including voice, video, web data, interactive network gaming and streaming media so there is a need to build a tool for the estimation of WiMAX traffic capacity calculations. Some methods and algorithms are analyzed and a tool has been built to ease the network planner’s job. It works based upon the calculations and algorithm presented in the report. Total number of users and data rate supported by a base station is calculated and total number of base stations, required for the coverage of a specific area is determined. This new tool is compatible with WRAP’s current functions.

Från Sjövärnskåren division syd, underavdelning Blekinge, inkom en förfrågan om att göra en undersökning och projektering till ett digitalt maskinövervakningssystem. Syftet med maskinövervakningssystemet är att det ska vara lättare för de som tränas ombord att ta till sig maskineriets kondition. Detta kommer att bidra till att minska underhållskostnaderna genom att förbättra övervakningen under drift, för att undvika oönskade driftfall, och dels att förbättra driftsdokumentationen som underlag för beslut om underhållsåtgärder/-intervaller. Projektet innebar en föreberedande undersökning av vilken utrustning som behövs till det nya systemet samt för att få en kostnadsram åt Sjövärnskåren. Vi träffades i Karlskrona för att komma överens om vilka maskinparametrar som skulle presenteras. Därefter påbörjades förundersökning och dokumentationsgenomgång för att ta reda på vilka givare det var samt vad för signal de gav till det befintliga övervakningssystemet. Detta visade sig bli en stor del av projektet som tog mycket tid. Vi var och mätte signalerna från givarna på fartyget utan att komma fram till slutsats. Efter att ha pratat med varv och underhållsenheter som fartyget varit i kontakt med under sin tid i försvaret, hittade vi en källa som var mycket kunnig i området. Denne uppgav muntligen information som innebar att givarna skulle ge standardsignal, 4-20 mA. Projektet fortskred med denna information och offertunderlag gjordes och skickades ut till olika företag som hade produkter som kunde klara av uppgiften. Det inkom tre system som skulle klara av uppgiften. Alla dessa innebär omfattande programmeringsarbete för att få controllern att hantera och presentera informationen som det är tänkt. Samtliga system programmeras med funktionsblock (FB) eller strukturerad text, (ST). Även för den insatte i dessa språk kommer det att bli en ansenlig mängd programmeringstimmar. / This exam work was initiated by a request from Sjövärnskåren division Syd. They wanted to implement a newer, computer based system with graphical display, an engine monitoring system which was ment to provide the engineer on watch with data from the engines. The object for this is to reduce the maintenance costs through improved monitoring while running and to improve documentation which later on the maintenance measures is based on. The project was an initial study which conclusions and recommendations on systems suited for the task is to give Sjövärnskåren an economical frame. We met up in Karlskrona on the ship and had a discussion about which parameters that should be presented. After that we started to go through the documentation and perform onsite surveys to conclude what signals the transmitters put out to the existing monitoring system. This was a delicate task, information about the transmitters was lacking in the documentation. The onsite measures gave no vital information. We talked to the shipyards and maintenance units that the ship had been in contact with during its time in the navy. We came in contact with a man that had been working with this ship, and he gave us information that told us that the transmitters were of standard type, 4-20 mA. With this information, the project pursued and we invited tenders to give us systems that could cope with the task. We had three tenders thar supplied us with systems. All of theese meant considerable programmingwork to get the monitoring system up and running.

No description available.

<p>This master's thesis presents the development of a collision handling function for Motoman industrial robots and investigates further use of the developed software. When a collision occurs the arm is to be retracted to a safe home location and the job is to be restarted to resume the production. The retraction can be done manually, which demands that the operator has to have good knowledge in robot handling and it might be a time consuming task. To minimise the time for restarting the job after a collision and allowing employees that have limited knowledge in robot handling to retract and restart the job, Motoman provides an automatical retraction function. However, the retraction function may cause further collisions when used and therefor a new function for retracting the arm is needed. The new function is based on that the motion of the robot is recorded by sampling the servo values, which are then stored in a buffer. A job file is automatically created and loaded into the control system, and the position variables of the job file are updated using the contents of the buffer. This will ensure a safe retraction of the arm as long as the environment surrounding the robot remains the same.</p><p>The developed software made it possible to control the robot in real-time by changing the buffer information, which has lead to a cognitive system called the Pathfinder. By initiating the Pathfinder function with at least a start and an end point, the function generates a collision free path between the start point and the end point. A pilot-study has also been made concerning integration of a vision system with the Pathfinder to increase the decision handling for the function.</p>

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 172-188).

Thesis--M. Phil., University of Hong Kong, 1974. / Mimeographed.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 182-186). Available also in a digital version from Dissertation Abstracts.

Thesis (MTech (Electrical Engineering))--Peninsula Technikon, 2002. / Word processed copy. Summary in English. Includes bibliographical references (leaves 170-179). Also available online.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy