This thesis compares the impact on disk performance in a GNU/Linux  environmentwith three encryption Algorithms: AES,  Serpent and Twofish in three different implementations: DM-crypt, Loop-AES and Truecrypt. For all three Algorithms a key length of 256 bits is used.The thesis shows that the least performance impact during data encryption, and thus file writing, is reached by using AES or Twofish encryption implemented in DM-crypt or TrueCrypt. The thesis shows that some data operations with a sufficiently low processor utilization barely affects disk performance at all if encrypted using the optimal implementation and Algorithm.It is also discovered that the performance impact during data decryption, or file reading, can be minimized by using the most efficient implementation and Algorithm. The best results are met with the AES or Twofish cipher, regardless of implementation.An important conclusion that  is  drawn is that it is hard to determine a superior encryption solution for all purposes. However, by reviewing and examining the collected data from all aspects of disk performance the AES implementation in TrueCrypt is, with small marginals, determined to be the most optimal..

A report on my thesis developing an Algorithm to automatically classify a mammogram image as containing an implant or not and segmenting and masking any present breast implant in the image..

In contemporary encryption the vast amount of text subject to cracking has brought about the demand for methods distinguish files more likely to be encrypted. The encryption software Truecrypt can encrypt files that are not possible to identify with a file signature. To solve the detection problem, an Algorithm sensitive to the absence of structure in the very code of files was developed. The program was written in the programming language EnScript which is built into the forensic software suite EnCase. The essential part of the Algorithm therefore deployes the statistic of a chi-square test for deviance from a uniform distribution to distinguish files with contents that appear to be random.

With numerous applications in both military and civilian life, the demand for accurate 3D models of real world environments increases rapidly. Using an airborne laser scanner for the raw data acquisition and robust methods for data processing, the researchers at the Swedish Defence Research Agency (FOI) in Linköping hope to fully automate the modeling process.The work of this thesis has mainly been focused on three areas: ground estimation, image segmentation and classification. Procedures have in each of these areas been developed, leading to a new Algorithm for ground estimation, a number of segmentation methods as well as a full comparison of various decision values for an object based classification. The ground estimation Algorithm developed has yielded good results compared to the method based on active contours previously elaborated at FOI. The computational effort needed by the new method has been greatly reduced compared to the former, as performance, particularly in urban areas, has been improved.

The purpose of this thesis work was to develop an automatic fault detection system for surveillance of bearing temperature in hydropower turbines. The parameters used except the bearing temperature were cooling water temperature and cooling water flow. A simple static model based on data sampled every minute was developed to estimate the bearing temperature. Then a detector for detection of change in bearing temperature based on the CUSUM-Algorithm was designed. Since the amount of data was very small the developed model was too uncertain to be used in a working system.The designed fault detection system showed to work well for the available data.

To United Minds, large-scale surveys are an important offering to clients, not least the public opinion poll Va?ljarbarometern. A risk associated with surveys is satisficing ? sub-optimal response behaviour impairing the possibility of correctly describing the sampled population through its results. The purpose of this study is to ? through the use of multivariate outlier detection methods - identify those observations assumed to be non-representative of the population.

Micronic Laser Systems AB produces and develops machines for the photo mask production market. One of their products is the Omega machine which exposes photo masks using 5 laser beams simultaneously. It is important that the distance between the each laser beam, the x-separation, is the same. The x-separation is today measured by exposing a photo mask with a certain pattern and thereafter measured with a metrology system. This takes to much time and it is desired to find a faster method to measure the x-separation without loosing precision.The task for this master thesis is to improve an existing measurement method which uses a calibration mask.

This study has been carried out in cooperation with Unilever and partly with the EC founded project, Smartdoc IST-2000-28137. In areas of statistics and image processing, both the amount of data and the dimensions are increasing rapidly and an interactive visualization tool that lets the user perform real-time analysis can save valuable time. Real-time cropping and drill-down considerably facilitate the analysis process and yield more accurate decisions. In the Smartdoc project, there has been a request for a component used for smart filtering in multidimensional data sets. As the Smartdoc project aims to develop smart, interactive components to be used on low-end systems, the implementation of the self-organizing map Algorithm proposes which dimensions to visualize.

In information retrieval there is a problem with ambiguous words. To solve this problem word sense disambiguation WSD is used. Few studies combining information retrieval and word sense disambiguation have been conducted with Swedish words. The purpose of this thesis has been divided in two. The first purpose was to examine Swedish information retrieval and disambiguation in the query phase.

This report analyzes and examines a hypothesis for finding a method to optimize thelength of the delubrication process time based on a total charge weight. The work hasfocused on the holding time for delubrication and the total charge weight.An important step in the manufacturing chain of cutting tools is when the greenbodies undergo the sintering process. Today, the delubrication step has the sameprocess time independent of the total charge weight. An implementation of a methodto adjust the delubrication process time would give more consistent quality of thecutting tool´s internal characteristics but also reduce the time course of the sinteringprocess. In the present project two methods for this goal were tested, thedevelopment of an Algorithm and a weight interval subdivision with associateddelubrication process times.During delubrication a pressure increase is observed due to the decomposition of thePEG in the powder mixture.

A key part in the development and verification of digital systems is simulation. But hardware simulators are expensive, and software simulation is not fast enough for designs with a large number of gates. As today?s digital zesigns constantly grow in size (number of gates), and that trend shows no signs to end, faster simulators handling millions of gates are needed. We investigate how to create a software gate-level simulator able to simulate a high number of gates fast.

This Master?s Thesis deals with a special problem that may be of importance when planning a frequency hopping mobile communication network. In normal cases the Frequency Assignment Problem is solved, in order to plan the use of frequencies in a network. The special case discussed in this thesis occurs when the network operator requires that the frequencies must be arranged into groups. In this case the Frequency Assignment Problem must be solved with respect to the groups, i.e.

In this report, we review various methods for generating valid sudoku with few hints. The report begins with a bit of terminology and anoverview of various methods that can be used to generate sudoku. Subsequently we go through the results of these generating methods, where wecan see that in order to generate sudoku with few clues, one must takespecial care how to place the clues of the sudoku. Finally we come to theconclusion that one of the neighbour-generating-method wasthe fastest Algorithm for generating sudoku..

This report deals with the modeling of a part of the communication system based on the IEEE 802.11a standard which represents the next generation of wireless LAN with greater scalability, better interference immunity and significantly higher speed, up to 54 Mbps. 802.11a uses Orthogonal Frequency Division Multiplexing (OFDM) where modulation is performed by an IFFT and the demodulation by an FFT. After modeling the FFT in Matlab and C, the FFT implementation has been validated using a soft microprocessor core by Xilinx (Microblaze) and the results were compared..

This project measures the upper bound of exposure time for laser reflection detection in the software DotDetector. Via measurement of the exposure time for which distortion happens in a room lit with everyday light we conclude that the upper bound for exposure times are 100 milliseconds. This value does not change as long as the lighting in the room is the same. As future work this project proposes variable upper bounds depending on secondary lighting in the room. Also we propose automating the colour masking of the detection Algorithm..