| 1. |
- Agelis, Sacki
(författare)
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Reconfigurable Optical Interconnection Networks for High-Performance Embedded
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In embedded computer and communication system the capacity demand for interconnection networks is increasing continuously in order to achieve high-performance systems. Recent breakthroughs show that by using reconfigurability inside a single chip substantial performance gains can be added. However, in this thesis the focus is on system level reconfigurability (between chips or modules) and the performance gains that potentially can be achieved by having support for runtime reconfigurability on the system level.This thesis addresses the field of runtime system level reconfigurability with the use of optics in switches and routers for data- and telecommunications, and in multi-processor systems used for embedded signal processing. Several reconfigurable systems for switching and routing with support to adapt for asymmetric traffic patterns are proposed and compared to identify how design choices affect flexibility, performance etc. The proposed solutions are characterized by their multistage optical interconnection networks with reconfigurable shuffle patterns, where the reconfigurability is provided by micro-optical-electrical mechanical systems. More specifically, application-specific bottlenecks can be resolved by reconfiguring the interconnection network according to the current application demands. The benefits of the architectural solutions are confirmed by simulations that clearly show that the architectures can achieve high performance for both symmetric application characteristics and for several classes of asymmetric application characteristics. The final architectural solution is characterized by electronic packet-switches interconnected through an optical backplane, which is reconfigurable. Moreover, the thesis presents how several signal processing applications can be mapped to run concurrently in a time-shared scheme on a single reconfigurable multi-processor system that has high flexibility to adapt for the application currently at hand. The interconnection network is then adapted (reconfigured) according to the demands of the currently executed application in each time instance. The analysis shows that it is feasible to build such a system with today’s components.
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| 2. |
- Assabie Lake, Yaregal, 1975-
(författare)
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Multifont recognition System for Ethiopic Script
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, we present a general framework for multi-font, multi-size and multi-style Ethiopic character recognition system. We propose structural and syntactic techniques for recognition of Ethiopic characters where the graphically comnplex characters are represented by less complex primitive structures and their spatial interrelationships. For each Ethiopic character, the primitive structures and their spatial interrelationships form a unique set of patterns.The interrelationships of primitives are represented by a special tree structure which resembles a binary search tree in the sense that it groups child nodes as left and right, and keeps the spatial position of primitives in orderly manner. For a better computational efficiency, the primitive tree is converted into string pattern using in-order traversal, which generates a base of the alphabet that stores possibly occuring string patterns for each character. The recognition of characters is then achieved by matching the generated patterns with each pattern in a stored knowledge base of characters.Structural features are extracted using direction field tensor, which is also used for character segmentation. In general, the recognition system does not need size normalization, thinning or other preprocessing procedures. The only parameter that needs to be adjusted during the recognition process is the size of Gaussian window which should be chosen optimally in relation to font sizes. We also constructed an Ethiopic Document Image Database (EDIDB) from real life documents and the recognition system is tested with respect to variations in font type, size, style, document skewness and document type. Experimental results are reported.
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| 3. |
- Bengtsson, Jerker
(författare)
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Efficient implementation of stream applications on processor arrays
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concludes work conducted on exploring the usage of parallel and reconfigurable processor architectures in industrial high-performance embedded systems. This kind of systems has by tradition been built using a mix of digital signal processors and custom made hardware. Digital signal processors provide full functional felxibility, but at the cost of lower performance. Custom made hardware can be optimized for specific functions for high performance, but at the cost of inflexibility and high development costs. A desire is to combine flexibility and performance using commercial hardware, without trading too much of performance for flexibility.Parallel and reconfigurable architectures provide a flexible computing space constituting processing elements that are coupled through configurable communication structures. Architectures designed with less complex processing elements render a high degree of utilizable parallelism at the cost of having to use a portion of the pocessing elements for control functions. In the thesis it is shown that it is possible to utilize this kind of architecture to achieve high performance efficiency, despite the fact that a large fraction of PEs are required to implement control-oriented portions in a fairly complex algorithm.A major problem is that architectures of this kind expose a very complex programming abstraction for compilers and programmers. The approach taken in this work is a domain-specific stream processing model which provides means to express application-specific dataflows and computations in terms of streams. An extensive application study comprising the baseband processing in radio base stations has been used to define sufficient data types, operators and language construct. Furthermore, to support industrial requirements on portability to different architectures, it must be possible to express parallelism and characteristic computations without exposing of hardware details in the source code.To be able to prototype and set up experiments with stream processing languages an experimental programming framework has been developed. A first prototype language with specific primitive types, operators and stream constructs has been implemented in order to elaborate with baseband programming. It is demonstrated how these types and operators can be used to express machine-independent bit field and other fine-grained data parallel computations. Furthermore, the language has been designed with constructs for efficient and flexible programming of reconfiguration of distributed function parameters.
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| 4. |
- Berggren, Eva, 1955-
(författare)
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Student Entrepreneurs : The Influence of University, Entrepreneurship Education and Research
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This licentiate thesis deals with the questions if and how entrepreneurship education and access to research at university stimulate student start-ups. The phenomenon of student entrepreneurs is approached in three empirical studies. In the first study mail questionnaires were sent out to former entrepreneurship students at three universities in Sweden, in order to find out if the students’ entrepreneurial behaviour was influenced by education. The second study explores differences in communication skills and the handling of liabilities of newness between entrepreneurs with entrepreneurship education at university and/or previous start-up experience. Student entrepreneurs are compared with a control group of randomly chosen Swedish entrepreneurs. In the third study, the influence from university research on student entrepreneurship as well as direct and indirect regional effects are examined through interviews with university spin-offs around Halmstad University. Entrepreneurship education at university is found to influence entrepreneurial behaviour, to increase the student’s awareness of business opportunities and to result in high start-up frequency early in life. The student entrepreneurs perceive fewer problems to handle some aspects of liability of newness as well as communicative skills in terms of openness and adaptation. Other-orientation is on the other hand supported by previous start-up experience. Hence, with experience from both entrepreneurship education and previous start-up, the students seem well prepared for future start-ups. The case study show multiple and long term indirect effects from student entrepreneurship in developing an entrepreneurial region. Established student entrepreneurs support less experienced student entrepreneurs by linking them to supplementary resources. Students are found to shoulder an important role as academic entrepreneurs in interaction with other individuals connected to the university.
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| 5. |
- Bergman, Lars
(författare)
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Using Multicoloured Halftone Screens for Offset Print Quality Monitoring
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the newspaper printing industry, offset is the dominating printing method and the use of multicolour printing has increased rapidly in newspapers during the last decade. The offset printing process relies on the assumption that an uniform film of ink of right thickness is transferred onto the printing areas. The quality of reproduction of colour images in offset printing is dependent on a number of parameters in a chain of steps and in the end it is the amount and the distribution of ink deposited on the substrate that create the sensation and thus the perceived colours. We identify three control points in the offset printing process and present methods for assessing the printing process quality in two of these points:• Methods for determining if the printing plates carry the correct image• Methods for determining the amount of ink deposited onto the newsprintA new concept of colour impression is introduced as a measure of the amount of ink deposited on the newsprint. Two factors contribute to values of the colour impression, the halftone dot-size and ink density. Colour impression values are determined on gray-bars using a CCD-camera based system. Colour impression values can also be determined in an area containing an arbitrary combination of cyan magenta and yellow inks. The correct amount of ink is known either from a reference print or from prepress information. Thus, the deviation of the amount of ink can be determined that can be used as control value by a press operator or as input to a control system.How a closed loop controller can be designed based on the colour impression values is also shown.It is demonstrated that the methods developed can be used for off-line print quality monitoring and ink feed control, or preferably in an online system in a newspaper printing press.
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| 6. |
- Bilstrup, Urban, 1971-
(författare)
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Design Space Exploration of Wireless Multihop Networks
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis explores the feasible design space of wireless multihop networks and identifies fundamental design parameters. In the process of exploring it is important to ignore all details and instead take a holistic view. This means that all protocol details are overseen, all details of radio wave propagation models are overseen and the system is modelled strictly on an architectural level. From a theoretical information perspective, there is a limit to the capacity that a certain bandwidth and a certain signal-to-noise ratio at the receiver can provide. This limit is approximated as a volume in the time-frequency-space domain. A single transmission is represented as an occupied volume in this domain. A wireless multihop network covers a spatial area, and the question is how multiple numbers of transmission volumes can be fit into a given limited spatial area. This volume fitting should be done in order to maximize the overall performance or to trade available resources to favour a specific characteristic in the wireless multihop network. The volume model is used for the design space exploration of a wireless multihop network. It is argued that the fault tolerance and the energy gain achieved in a multihop topology are its strength as compared to a single-hop architecture. It is further shown that the energy gain is achieved at the expense of delay and a greater end-to-end error probability. This indicates that these parameters must be very carefully balanced in order to gain in the global overall performance perspective. It can further be concluded that the overall spatial capacity is increased as a result of the spatial channel reuse in a multihop topology. On the other hand, it is also shown that the multihop topology introduces a rather stringent geometrical capacity limitation when the number of nodes of a wireless multihop network is increased. The dynamics (e.g. node mobility, changing radio channels etc.) of a large scale wireless multihop network is also a limiting factor. The nodes’ mobility creates a knowledge horizon beyond which very little can be known about the present network topology.
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| 7. |
- Cabanettes, Frédéric, 1982-
(författare)
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Cam Roller Contact : The topographical aspect
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The automotive industry and the design of engines are strongly ruled by performance and legislation demands. First order aspects defining the main functions of a component are well known and new challenges appear at a lower scale. Wear reduction is defined as a second order problem and requires decreasing the scale of observation of components down to roughness. This thesis work and its aim lie within the scope of wear improvements and are focused on the injection cam/roller contact of heavy duty diesel engines. In order to reach the aim several material and methods are used: a valve train rig test, roughness characterisation and different manufacturing processes. It is shown by experiments that the flank and nose of injection cams are specific areas with specific roughness (higher density of summits Sds) compared to the rest of the cam. The wear is characterized by rounded-off of summits (Ssc). From those results and since wear processes are strongly linked to the pressure generated between the mating surfaces, the development of a rough contact model is of great interest. An elastic rough contact model is implemented and improved later on by an elasto-plastic description of materials. The simulations are validated by a wear test and are used to rank the ability of surfaces (both cam and roller) to face wear problems. The ratio of plastically deformed peaks shows that the flank and nose of the cam are reacting badly to pressures. Additionally the rough contact allows ranking/optimization of different machining processes with respect to their expected functional contact performance. Future work will be to use such a model to choose a good combination of surfaces (cam and roller) in order to reduce wear.
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| 8. |
- Dimkovski, Zlate
(författare)
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On Surface Topography of Cylinder Liners
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The frictional losses, oil consumption and emissions in internal combustion engines are in great extent controlled by the cylinder liner surface topography. This emphasises the importance of: investigating the liner’s topography by objectively characterising it, investigating its effects on the tribological function to gain a better understanding and improving its manufacturing. As a first attempt in this study to objectively characterise the liner surface, a traditional combination of Scanning Electron Microscope (SEM) images and roughness profiles was used. The groove and image parameters characteristic for liner topographies were extracted by applying specially developed algorithms and together with the standard parameters served to study wear on liners of diesel and petrol engines. An experiment was designed to improve the liners’ manufacturing by varying of the honing process parameters and oil flow simulations were run to study the influence of the characteristics of the manufactured surfaces on their function. The results suggested that reducing the base honing pressure and increasing the plateau honing time gave the best surface with smoother plateaux, summits of higher density and milder slopes, more but smaller islands and shallower valleys. The potentials of fast acquiring and containing 3D data of the interference measurements were utilised to overcome the encountered problems in the usage of the combination of profile and SEM measurements and to enable automatic quality control of the cylinder liner surfaces. In the efforts to examine the influence of the surface properties on liner’s function, the extent of blechmantel (cold work material) removal was estimated from 3D measurements of run liners in engine tests. For characterising this feature, algorithms were developed and implemented and it was found that the most of the blechmantel is still left on the liner pointing that it plays a minor role on wear.
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| 9. |
- Ejnarsson, Marcus
(författare)
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Data Mining and Analysis for Characterizing Paper from On-line Multisensor Measurements
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this thesis is to develop a multi-resolution tool for screening paper formation variations, aiming to detect abnormalities in various frequency regions ranging from millimeters to several meters. The abnormalities detected in different frequency regions give an indication for the paper maker about specific disturbances in the paper production process. A paper web, running at a speed of 30 m/s, is illuminated by two red diode lasers and the reflected light are recorded as two time series of high resolution measurements constitutes the input signal to the papermaking process monitoring system. The time series are divided into blocks and each block is analyzed separately. The task is treated as a kernel based novelty detection applied to a multi-resolution time series representation obtained from the frequency bands of the Fourier power spectra of the blocks. The frequency content of each frequency region is characterized by a feature vector, which is transformed using the canonical correlation analysis and then categorized into the inlier or outlier class by the novelty detector. The ratio of outlying data points, significantly exceeding the predetermined value, indicates abnormalities in the paper formation. The experimental investigations performed have shown that the presented paper formation deficiencies monitoring technique and the system can be used for on-line monitoring of paper deficiencies manifesting themselves in a broad frequency range. A software, implementing the technique, was developed and used for online paper formation monitoring at a Swedish paper mill.
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| 10. |
- Elm, Annika, 1958-
(författare)
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Interaktion och naturvetenskap i en förskola och en förskoleklass
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med det här forskningsarbetet är att öka förståelsen av hur mönster i interaktionsprocesser påverkar barn och lärare i samtidiga skeenden. Studien syftar även till att öka insikten om hur naturvetenskapligt innehåll väljs ut och gestaltas i samspel mellan såväl barn som barn och lärare i en förskola och förskoleklass. De övergripande forskningsfrågorna är: Vilka interaktionsmönster dominerar när naturvetenskapligt innehåll behandlas? Vilka handlingar påverkar händelseförloppet? Hur väljs det naturvetenskapliga innehållet ut? Hur gestaltas det naturvetenskapliga innehållet i de specifika situationer som studeras? Därutöver syftar arbetet till att genomföra en metodstudie i avsikt att diskutera metodologiska val och analysprocessen. Teoretiska utgångspunkter tar avstamp ur konstruktionistisk teori med förankring i sociologisk interaktionsforskning. Undersökningen genomfördes i en förskola och en förskoleklass. På en förskoleavdelning medverkade en lärare och sex barn i åldern två till fyra år. I förskoleklassen medverkade två lärare och fjorton barn i åldern fem till sex år. De olika situationerna har dokumenterats med hjälp av videokamera och därefter analyserats i ett videoanalysprogram. Begreppen språkbruk och naturvetenskapliga aktiviteter har använts som raster för att strukturera och systematisera materialet. Resultatet visar att naturvetenskapliga aktiviteter som utgörs av observation och undersökning samt frågor som behandlar djur och natur dominerar i de specifika sammanhang som studerats. Interaktionsmönstret visar på konstellationer av barn som återkommande bildar team i olika situationer. Lärarna och vissa team avbarn väljer och styr därmed hur de innehållsliga aspekterna gestaltas i de naturvetenskapliga aktiviteterna.
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