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Sökning: db:Swepub > Fritt online > Licentiatavhandling > Högskolan i Halmstad

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1.
  • Bergman, Lars (författare)
  • Using Multicoloured Halftone Screens for Offset Print Quality Monitoring
  • 2005
  • Licentiatavhandling (övrigt vetenskapligt)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.
2.
3.
  • Gebrewahid, Essayas, 1984- (författare)
  • Compiling Concurrent Programs for Manycores
  • 2015
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • The arrival of manycore systems enforces new approaches for developing applications in order to exploit the available hardware resources. Developing applications for manycores requires programmers to partition the application into subtasks, consider the dependence between the subtasks, understand the underlying hardware and select an appropriate programming model. This is complex, time-consuming and prone to error.In this thesis, we identify and implement abstraction layers in compilation tools to decrease the burden of the programmer, increase programming productivity and program portability for manycores and to analyze their impact on performance and efficiency. We present compilation frameworks for two concurrent programming languages, occam-pi and CAL Actor Language, and demonstrate the applicability of the approach with application case-studies targeting these different manycore architectures: STHorm, Epiphany and Ambric.For occam-pi, we have extended the Tock compiler and added a backend for STHorm. We evaluate the approach using a fault tolerance model for a four stage 1D-DCT algorithm implemented by using occam-pi’s constructs for dynamic reconfiguration, and the FAST corner detection algorithm which demonstrates the suitability of occam-pi and the compilation framework for data-intensive applications. We also present a new CAL compilation framework which has a front end, two intermediate representations and three backends: for a uniprocessor, Epiphany, and Ambric. We show the feasibility of our approach by compiling a CAL implementation of the 2D-IDCT for the three backends. We also present an evaluation and optimization of code generation for Epiphany by comparing the code generated from CAL with a hand-written C code implementation of 2D-IDCT.
4.
  • Hedenberg, Klas, 1968- (författare)
  • Obstacle Detection for Driverless Trucks in Industrial Environments
  • 2014
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • With an increased demand on productivity and safety in industry, new issues in terms of automated material handling arise. This results in industries not having a homogenous fleet of trucks and driven and driverless trucks are mixed in a dynamic environment. Driven trucks are more flexible than driverless trucks, but are also involved in more accidents. A transition from driven to driverless trucks can increase safety, but also productivity in terms of fewer accidents and more accurate delivery. Hence, reliable and standardized solutions that avoid accidents are important to achieve high productivity and safety. There are two different safety standards for driverless trucks for Europe (EN1525) and U.S. (B56.5–2012) and they have developed differently. In terms of obstacles, they both consider contact with humans. However, a machinery-shaped object has recently been added to the U.S. standard (B56.5–2012). The U.S. standard also considers different materials for different sensors and non-contact sensors. For obstacle detection, the historical contact-sensitive mechanical bumpers as well as the traditional laser scanner used today both have limitations – they do not detect hanging objects. In this work we have identified several thin objects that are of interest in an industrial environment. A test apparatus with a thin structure is introduced for a more uniform way to evaluate sensors. To detect thin obstacles, we used a standard setup of a stereo system and developed this further to a trinocular system (a stereo system with three cameras). We also propose a method to evaluate 3D sensors based on the information from a 2D range sensor. The 3D model is created by measuring the position of a reflector with known position to an object with a known size. The trinocular system, a 3D TOF camera and a Kinect sensor are evaluated with this method. The results showed that the method can be used to evaluate sensors. It also showed that 3D sensor systems have potential to be used on driverless trucks to detect obstacles, initially as a complement to existing safety classed sensors. To improve safety and productivity, there is a need for harmonization of the European and the U.S. safety standards. Furthermore, parallel development of sensor systems and standards is needed to make use of state-of-the-art technology for sensors.
5.
  • Hertz, Erik, 1956- (författare)
  • Parabolic Synthesis
  • 2011
  • Licentiatavhandling (övrigt vetenskapligt)
6.
  • Hinic, Hansi (författare)
  • Psykologiska, sociala och motivationsfaktorer inom ungdomsfotbollen
  • 2004
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • Vilka faktorer som motiverar ungdomar att idrotta samt hur självkänsla, upplevdkompetens och faktorn ”ha skoj” är relaterade till olika motivationsfaktorer har undersöktsi denna studie. Vidare undersöktes ungdomars upplevelse av samt föräldrarsuppfattning om hur föräldrainvolveringen sker. Dessutom studerades hur föräldrainvolveringär relaterad till motivationsfaktorer, upplevd kompetens, faktorn ”ha skoj”samt individens självkänsla hos flickor och pojkar samt om det finns skillnader mellankönen vad gäller dessa aspekter. Totalt deltog 425 fotbollsspelande flickor och pojkar iåldern 12-18 år. De besvarade ett enkätbatteri angående motivation, självkänsla,upplevd kompetens, faktorn ”ha skoj” samt föräldrainvolvering. Därutöver deltog 797föräldrar som besvarade frågor om föräldrainvolvering. Resultaten visade attungdomar främst motiverades av faktorerna ”ha roligt”, ”hälsa” samt ”laganda”.Flickor motiverades mer av faktorn ”laganda” och pojkar mer av faktorn ”utvecklafärdigheterna”. Dessutom var självkänsla positivt relaterad till inre motivationsfaktorer.Ungdomarnas upplevelse av föräldrainvolvering stämde överlag överens medvad föräldrarna rapporterade. Vidare var självkänsla positivt relaterad till upplevtberöm och förståelse samt negativt till upplevd press från föräldrarna. Även faktorernaupplevd kompetens och ”ha skoj” var positivt relaterade till självkänsla. Ingaskillnader erhölls vad gäller fysiskt aktiva föräldrar jämfört med icke fysiskt aktivaföräldrar på rapportrad föräldrainvolvering eller ungdomars upplevelse av föräldrainvolvering.Flickors bassjälvkänsla var endast relaterad till faderns involvering medanpojkars var relaterad till både moderns och faderns involvering. Upplevd kompetensoch faktorn ”ha skoj” var positivt relaterade till moderns respektive faderns beröm ochförståelse hos pojkar men inte hos flickor. En slutsats av denna studie är att idrotten iändå högre utsträckning än i dag bör betona aspekter såsom ”ha skoj”, ”laganda”, samt”utveckla färdigheterna” i sin verksamhet. Föräldrar bör inta en positiv attityd till sinabarns idrottande, vilket inbegriper såväl beröm som förståelse. Tillsammans, medföräldrarna, kan idrottsrörelsen skapa en god miljö för ungdomar att idrotta i ochdärmed bidra till att ungdomarna grundlägger en livslång vana av regelbunden fysiskaktivitet.
7.
  • Hoang, Le-Nam, 1984- (författare)
  • Relaying for Timely and Reliable Message Dissemination in Wireless Distributed Control Systems
  • 2015
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • Distributed control applications enabled by wireless networks are becoming more and more frequent. The advantages of wireless access are many, as control systems become mobile, autonomous and connected. Examples include platooning and automated factories. However, distributed control systems have stringent requirement on both reliability and timeliness, the latter in terms of deadlines. If the deadline is missed, the packet is considered useless, similarly to a lost or erroneous packet in a system without deadlines. In addition, wireless channels are, by nature, more exposed to noise and interference than their wired counterparts. Consequently, it implies a considerable challenge to fulfill the deadline requirements with sufficient reliability for proper functionality of distributed control applications. However, by taking advantage of cooperative communications, increased reliability can be achieved with little or no additional delay.Reducing the delay until a message is successfully received is a two-fold problem: providing channel access with a predictable maximum delay and maximizing the reliability of each transmission, once granted by the medium access method. To this end, this thesis proposes a framework that provides a bounded channel access delay and handles the co-existence of both time-triggered and event-driven messages encountered in distributed control applications. In addition, the thesis proposes and evaluates an efficient message dissemination technique based on relaying that maximizes the reliability given a certain deadline, or alternatively determines the delay required to achieve a certain reliability threshold for both unicast and broadcast scenarios. Numerical results, which are verified by Monte-Carlo simulations, show significant improvements with the proposed relaying scheme as compared to a conventional scheme without cooperation, providing more reliable message delivery given a fixed number of available time-slots. It also becomes clear in which situations relaying is preferable and in which situations pure retransmissions are preferable, as the relay selection algorithm will always pick the best option. The relay selection algorithm has a reasonable complexity and can be used by both routing algorithms and relaying scenarios in any time-critical application as long as it is used together with a framework that enables predictable channel access. In addition, it can be implemented on top of commercially available transceivers.
8.
  • Johannesson, Karin, 1982- (författare)
  • Analysis of phosphorus retention variations in constructed wetlands receiving variable loads from arable land
  • 2011
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • Seven wetlands, constructed on agricultural land in the south of Sweden, were investigated with respect to phosphorus (P) retention. The overall aim was to increase the understanding of P retention and find possible explanations for the variations in retention that have been observed in previous studies. This was done by i) investigating P retention in wetlands receiving various water and P loads, ii) investigating the effect of variations in water flow on P transport, iii) comparing how well retention estimates based on water quality data agreed with measurements of the amount of P accumulated in the sediment.Results showed that P retention was positive in all wetlands, but it was variable (1–58 kg ha-1 yr-1) and months with negative retention were observed in nearly all wetlands. Such  monthly negative retention coincided with i) high flow periods, when particulate P was either flushed straight through the wetlands or resuspended from the bottoms, and ii) warm low flow periods, in which case dissolved P was probably released from wetland sediments due to anoxic conditions.The results from the two methods for estimating P retention differed. Based on water quality data, the total P load during four years was 65 kg ha-1 and the mean P retention 2.8 kg ha-1 yr-1, or 17% of the total P load. In contrast, the amount of P accumulated in the inlet zone alone amounted to 78% of the P load, and the P content in the upper sediment of the whole wetland area exceeded the P load with a factor four. This discrepancy showed the need to add studies of sediment accumulation to inflow-outflow estimates for an improved understanding of wetland P retention.
9.
  • Johansson, Pontus, 1975- (författare)
  • Design and Development of Recommender Dialogue Systems
  • 2004
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • The work in this thesis addresses design and development of multimodal dialogue recommender systems for the home context-of-use. In the design part, two investigations on multimodal recommendation dialogue interaction in the home context are reported on. The first study gives implications for the design of dialogue system interaction including personalization and a three-entity multimodal interaction model accommodating dialogue feedback in order to make the interaction more efficient and successful. In the second study a dialogue corpus of movie recommendation dialogues is collected and analyzed, providing a characterization of such dialogues. We identify three initiative types that need to be addressed in a recommender dialogue system implementation: system-driven preference requests, userdriven information requests, and preference volunteering. Through the process of dialogue distilling, a dialogue control strategy covering system-driven preference requests from the corpus is arrived at.In the development part, an application-driven development process is adopted where reusable generic components evolve through the iterative and incremental refinement of dialogue systems. The Phase Graph Processor (PGP) design pattern is one such evolved component suggesting a phase-based control of dialogue systems. PGP is a generic and flexible micro architecture accommodating frequent change of requirements inherent of agile, evolutionary system development. As PGP has been used in a series of previous information-providing dialogue system projects, a standard phase graph has been established that covers the second initiative type; user-driven information requests. The phase graph is incrementally refined in order to provide user preference modeling, thus addressing the third initiative type, and multimodality as indicated by the user studies. In the iterative development of the multimodal recommender dialogue system MADFILM the phase graph is coupled with the dialogue control strategy in order to cater for the seamless integration of the three initiative types.
10.
  • Jonsson, Magnus, 1969- (författare)
  • Fiber-optic interconnections in high-performance real-time computer systems
  • 1997
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • Future parallel computer systems for embedded real-time applications,where each node in itself can be a parallel computer, are predicted to havevery high bandwidth demands on the interconnection network. Otherimportant properties are time-deterministic latency and guarantees to meetdeadlines. In this thesis, a fiber-optic passive optical star network with amedium access protocol for packet switched communication in distributedreal-time systems is proposed. By using WDM (Wavelength DivisionMultiplexing), multiple channels, each with a capacity of several Gb/s, areobtained.A number of protocols for WDM star networks have recently been proposed.However, the area of real-time protocols for these networks is quiteunexplored. The protocol proposed in this thesis is based on TDMA (TimeDivision Multiple Access) and uses a new distributed slot-allocationalgorithm with real-time properties. Services for both guarantee-seekingmessages and best-effort messages are supported for single destination,multicast, and broadcast transmission. Slot reserving can be used toincrease the time-deterministic bandwidth, while still having an efficientbandwidth utilization due to a simple slot release method.By connecting several clusters of the proposed WDM star network by abackbone star, thus forming a star-of-stars network, we get a modular andscalable high-bandwidth network. The deterministic properties of thenetwork are theoretically analyzed for both intra-cluster and inter-clustercommunication, and computer simulations of intra-cluster communicationare reported. Also, an overview of high-performance fiber-opticcommunication systems is presented.
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