<p>This master thesis presents PORDaS, the Peer-to-peer Object Relational Database System. It is a continuation of work done in a project of fall 2005, where the foundation for the thesis was laid down. The focus of the work is on distributed query processing between autonomous databases in a structured peer-to-peer network. A great deal of effort has gone into compiling the theoretical foundation for the project, which served as a basis for assessing alternative approaches to introducing a query processor in a peer-to-peer database. The old PORDaS version was extended to include a simplified, pipelined query processor capable of joining tables. The query processor had two different execution strategies, the first was performing join operators at the requesting node and the second was performing join operators parallel among the nodes participating in the query. Experiments which ran PORDaS on a cluster of 36 computers showed that there are room for improvements even though the system was able to perform all the tests.</p>

<p>Today more and more companies acquire enterprise-scale solutions for their organization. Enterprise-scale solutions connect departments and business functions in the organization in order to facilitate the coordination, communication, and work flow between them. However, when systems get more interconnected and complex, they are also more prone to faults. If business critical parts of the system are affected, this can be devastating for a company. When designing large enterprise scale systems, one uses a wide range of specialized models with different view points and applications. This fragmentation and specialization of the representation of the system decreases the clarity of the total enterprise model and implies that it is difficult to analyze the enterprise as a whole. To overcome this problem, specialized software tools that can integrate the sub models in a total model can be developed. This thesis will develop a tool assisted extended process to the development process Rational Unified Process that helps analyzing the design of enterprise solutions by integrating the behavioral and structural models of the system into a unified representation. The tools take basis in digitized models represented in UML, the industry standard language for modeling software systems. We will focus on the two quality attributes availability and criticality.</p>

<p>This project was started to develop a new improved version of the Peer2Me framework. After having evaluated the first version of the Peer2Me framework in our depth study project in the fall of 2005, quite a few possible improvements came up. This report starts with an introduction to Computer Supported Cooperative Work (CSCW), wireless networking, Peer-to-Peer (P2P) computing, and mobile ad hoc networking. It also introduces some central concepts concerning design of a software architecture, and technology relevant to the development of the Peer2Me framework. The redesign of the framework was started by eliciting a set of new requirements, constituting the basis for designing the new Peer2Me architecture. Through an iterative and incremental development process, Peer2Me framework v2.0 was developed with several new features. An instant messenger application has been developed using both versions of the framework, in order to compare them. A thorough comparison of Peer2Me v1.0 and Peer2Me v2.0 shows that the redesign has resulted in a reduced framework footprint and complexity, a simplified interface towards the MIDlets, and a considerably increase in transfer rate.</p>

<p>Today's way of life includes increasing amounts of information, and therefore handling and processing of information. Almost everything you do involves some sort of a computer somewhere, and many businesses have implemented comprehensive computer systems into their corporative structure, to serve both employees and customers. But if a new service is introduced to the users, or a new group of users are introduced to an existing service, how do you know if the performance will be satisfying? To deal with such questions, a method called The Scalability Assessment Method (SAM) has been developed. The Scalability Assessment Method is a general procedure for evaluating the scalability of a system architecture. Other projects have applied SAM to real reference systems, and their results have shown that SAM is a method that can be trusted to give credible predictions. Until recently, dedicated software tools that support the SAM method have been absent, and the researchers have been using i.a. spreadsheets in an ad hoc approach to the problems. Therefore, a SAM software package is in development. The SAM Engine (SAMe) is a Java program developed in this project, with an intuitive user interface that is enabling a non-expert user to apply the method on a desired architecture. This report documents the development of the prototype SAM Engine (SAMe), and how the program supports the SAM method. Keywords: Performance evaluation, scalability, simulation, Structure and Performance, SAM.</p>

<p>The emergence of complex data objects that must to be indexed and accessed in databases has created a need for access methods that are both dynamic and efficient. Lately, metric tree structures have become a popular way of handling this because of the advantages they have compared to traditional methods based on spatial indexing. The most common way to handle indexing is to build tree structures and then prune out branches of the trees during search, and for a dynamic indexing structure it is important that these trees stay balanced in order to keep the worst case search time as low as possible. Normally, this is done based on complex criteria and reshuffling operations. Another way to handle balancing is General Balanced Trees (GBT), proposed by Arne Andersson (Journal of Algorithms 30, 1999), which uses simple, global criteria for rebalancing binary search trees by using total and partial rebuilding. This thesis explores if it is possible to apply this to metric tree structures, and especially two static metric tree structures called the Vantage Point Tree and the Multiple Vantage Point Tree. It discusses how to best make these into dynamic tree structures and how to apply balancing by using GBT paradigms on them. The results of the performance of the new tree structures are analyzed, and the results are compared against already existing structures. The results shows that this works for balancing the trees, and that the structures perform reasonably well compared to already existing structures.</p>

<p>In a dense and complex emitter environment, a high pulse arrival rate and a large number of interleaved radar pulse sequences is expected, from both agile and stable emitters. This thesis evaluates the combination of interval-only algorithms with different monopulse parameters, in comparison to a neural network to do accurate emitter classification. This thesis has evaluated a selection of TOA deinterleaving algorithms with the intent to clearly discriminate between pulses emitted from agile emitters. The first section presents the different techniques, with emphasis on pinpointing the different algorithmic structures. The second section presents a neural network combinational recognition system, with a main focus on the fuzzy ARTMAP neural network, where also some practical implementations has been presented. The final section gives a partial system evaluation based on some statistical means, seeking to get an estimate on the information flow from the ESM receiver as a function of both the density and the expected parametric values, i.e. PW since this is proportional to the amount of processed pulses.</p>

<p>This thesis is a continuation of my previous work `Supporting Notetaking with Digital Writing System: the case of teacher education’. The main goal of this thesis is to design a customized digital pen and paper based note taking system for the practice based teacher education, PPE. This thesis work has further performed a literature review to state the pedagogical objectives of PPE. Literature review on state-of-the-art has also been carried out. Together, these researches have informed the development of deployment scenarios and requirements for the system design. The system design is based on the Logitech io2 system deployed in my previous work. The system design extends the original system with a specialized paper design and a functionality to invoke storing of notes to specified folders at note taking time. The system has been evaluated by both experts and users, and has received positive feedback from both groups. The feedback is presented in this thesis to inform possible further work with this system</p>

<p>Clustering in a data mining setting has been researched for decades. Lately, document clustering used to cluster web search engine results have recieved much attention. Large companies such as Google and Microsoft have shown their interest and we have seen the emergence of commercial clustering engines such as Vivisimo. This thesis shows how a search engine with clustering capabilities can be developed. The approach described has been implemented as a working prototype that allows searching and browsing clusters through a web interface. The prototype has been evaluated in a user survey and through informal testing.</p>

<p>The concept of software-defined radio (SDR) holds great promise. The idea behind SDR is to move software as close to the antenna as possible. This can improve flexibility, adaptability and reduce the time-to-market. This thesis covers the evaluation of algorithms for implementing IEEE 802.15.4 physical layer. In collaboration with a digital circuit designer some of these algorithms were chosen and formed a basis for a DSP architecture optimized for low-complexity, low-power radio standards. The performance of a implementation using these algorithms were then evaluated by means of analytical computations and by simulation</p>

<p>Today, dogs and humans are used in rescueing victims from disasters involving collapsed buildings, trapped tunnels and so forth. However, in some cases, robots have been deployed to assist the rescue teams. The tragic events of the World Trade Center in 2001 involved Urban Search and Rescue (USAR) robots pioneering rescue search with the help of information technology and robotics engineering. This report describes the design and implementation of a safety-critical system of a USAR robot model which will serve as a basis for analysis and development of future USAR robots. The scenario used in the experiment is a USAR robot prototype searching for survivors in a building which has collapsed. We analyse the scenario on a real prototype made up of Lego Mindstorms parts and equipped with a camera relaying real-time images to a workstation. The paper is a continuation of the report I submitted in December 2005; "Identifying the risks involved in the design of a safety-critical system for an Urban Search and Rescue robot".</p>