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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
361

Lossless image compression for aerospace non-destructive testing applications

Lin, Xin-Yu January 2004 (has links)
This thesis studies areas of image compression and relevant image processmg techniques with the application to Non-destructive Testing (NDT) images of aircraft components. The research project includes investigation of current data compression techniques and design of efficient compression methods for NDT images. Literature review was done initially to investigate the fundamental principles of data compression and existing methods of lossless and lossy image compression techniques. Such investigation provides not only the theoretical background, but also the comparative benchmarks for the research project. Chapter 2 provides general knowledge of image compression. The basic predictive coding strategy is introduced at the beginning of chapter 3. Fundamental theories of the Integer Wavelet Transform (IWT) can be found in chapter 4. The research projects proposed mainly three innovative methods for lossless compression of NDT images. Namely, the region-based method that employs region­oriented adaptation; the texture-based method that employs a mixed model for the prediction of image regions with strong texture patterns; and a hybrid method that utilizes advantages from both predictive coding and IWT coding. The main philosophy of lossless image compression is to de-correlate the original image data as much as possible by mapping from spatial domain to spatial domain in the predictive coding strategy or from spatial domain to transform domain in the IWT coding strategy. The proposed region-based method aims to achieve the best mapping by adapting the de-correlation to the statistical properties of decomposed regions using the component's CAD model. With the aid of component CAD models to divide the NDT images of aircraft components into different regions based on the material structures, the design of the predictors and the choice of the IWT are optimised according to the specific image features contained in each region having the same material structure. The texture-based method achieves the best de-correlation by using a mixed data model in the region possessing strong texture patterns. A hybrid scheme for lossless compression of the NDT images of aircraft components is presented. The method combines the predictive coding and the IWT. After region-based predictive coding, the IWT is applied to the error images produced for each decomposed region to achieve further image de-correlation by preserving the information contained in the error images with fewer transform coefficients. The main advantages of using the IWT are its multi-resolution nature and lossless property with integer grey level values in images mapped to integer wavelet coefficients. The proposed methods are shown to offer a significantly higher compression ratio than other compression methods. The high compression efficiency is seen to be achieved by not only a combination of the predictive coding and the IWT, but also optimisation in the design of the predictor and the choice of the transform according to the specific image features contained in each region having similar material structures.
362

Development and analysis of hybrid adaptive neuro-fuzzy inference systems for the recognition of weak signals preceding earthquakes

Konstantaras, Anthony J. January 2004 (has links)
Prior to an earthquake, there is energy storage in the seismogenic area, the release of which results in a number of micro-cracks, which in effect produce a weak electric signal. Initially, there is a rapid rise in the number of propagating cracks, which creates a transient electric field. The whole process lasts in the order of several tens of minutes, and the resulting electric signal is considered as an electric earthquake precursor (EEP). Electric earthquake precursor recognition is mainly prevented by the very essence of the signal itself. The nature of the signal, according to the theory of propagating cracks, is usually a very weak electric potential anomaly appearing on the Earth's electric field prior to an earthquake, often unobservable within the severely stronger embedded in noise electric background. Furthermore, EEP signals vary in terms of duration and size making reliable recognition even more difficult. The work described in this thesis incorporates neuro-fuzzy technology for the reliable recognition of EEP signals within the electric field. Neuro-fuzzy networks are neural networks with intrinsic fuzzy logic abilities, i.e. the weights of the neurons in the network define the premise and consequent parameters of a fuzzy inference system. In particular, the adaptive neuro-fuzzy inference system (ANFIS) is used, which has been shown to be effective as a universal approximator that can match any input/output data set, providing the system is adequately trained. An average model for EEP signals has been identified based on a time function describing the evolution of the number of propagating cracks. Pattern recognition is performed by the neural network to identify the average EEP model from within the electric field. The fuzzy nature of the neuro-fuzzy model, though, enables the network to classify as EEPs, signals that are not exactly the same but do approximate the average EEP model. On the other hand, signals that look like EEPs but do not approximate enough the average model are being suppressed preventing false classification. The effectiveness of the proposed network is demonstrated using electrotelluric data recorded in NW Greece in 1995. Following training, testing with unseen data verifies the reliable performance of the model.
363

Är STCW-kraven i STCW A-III/1 uppfyllda i kursplanerna? : En litteraturstudie om Sjöfartshögskolan i Kalmars kursplaner och STCW-koden

Winbäck, Gustav January 2017 (has links)
Huvudfrågeställningen i studien var om Sjöfartshögskolan i Kalmar kursplaner uppfyller de krav som ställs i STCW del A-III/1 på utbildningsprogrammen för sjöingenjörer. Syftet med arbetet var att verifiera Sjöfartshögskolan i Kalmars kursplaners uppfyllelse av STCW-kraven enligt del A-III/1 för sjöingenjörer. Metoden som användes var en kvalitativ litteraturstudie där de i STCW uppställda kraven enligt del A-III/1 studerades och jämfördes med kursplanerna inom utbildningsprogrammet för sjöingenjörer på Sjöfartshögskolan i Kalmar.  Resultatet som framkom var att 72 % av kraven i A-III/1 var uppfyllda i kursplanerna för Sjöingenjörsprogrammet i Kalmar. Min rekommendation är att kursplanerna ses över och justeras för att bättre stämma överens med STCW-kraven, för att säkerhetsställa att kvaliteten på utbildningen är hög och konstant.
364

Framställning av en utvärderingsapplikation med Node.js

Gharam, Dimitri January 2017 (has links)
Webbapplikationer baseras på en klient-server modell. På klientsidan används HTML, CSS och JavaScript för att implementera struktur, estetik och interaktivitet till varje enskild webbsida. På serversidan stöds logiken i webbapplikationen av en solution stack som består av ett operativsystem, en DBMS, en webbserver och ett skriftspråk. Dessa nämnda mjukvarulösningar representerar de traditionella lösningar som används för framtagning av serverbaserade lösningar. Node.js är en alternativ teknologi som skapar serverbaserade lösningar med hjälp av JavaScript, som normalt används för utveckling av klientbaserade lösningar. Syftet med detta arbete är att ge en översikt över Node.js och dess moduler, samt demonstrera hur de används genom framtagning av en webbapplikation där man utför utvärderingar under en föreläsning. Slutsatsen är att Node.js är en teknologi, som erbjuder lösningar baserade på både prestanda och lägre minnesförbrukning. Eftersom Node.js lösningar är skrivna i JavaScript, kan det vara ett enklare alternativ att använda för frontendutvecklare. / Web-based applications follow a client-server model. On the client side, HTML, CSS and JavaScript are web-technologies employed to implement the structure, style and interactivity of web pages respectively. On the server side, the logic of web application is supported by a solution stack, which defines the operating system, the web-server, the database management system and the programming language. The forementioned software systems are the traditional technologies employed to develop web systems. Node.js is an alternative web technology that provides both a web server and a programming capabilities using JavaScript. This means that JavaScript can now be used both on client and server sides. This work aims to provide an overview of Node.js and its packages, as well as a demon- stration of their use with the implementation of a web application for lecture eva- luation. As a conclusion, Node.js is a competitive server side technology because Node.js provides solutions based on both performance and low memory consump- tion. Moreover, as Node.js applications are written in JavaScript, it might be a easier option to use for front-end developers.
365

Automatic image alignment for clinical evaluation of patient setup errors in radiotherapy

Su, QingLang January 2004 (has links)
In radiotherapy, the treatment is typically pursued by irradiating the patient with high energy x-ray beams conformed to the shape of the tumour from multiple directions. Rather than administering the total dose in one session, the dose is often delivered in twenty to thirty sessions. For each session several settings must be reproduced precisely (treatment setup). These settings include machine setup, such as energy, direction, size and shape of the radiation beams as well as patient setup, such as position and orientation of the patient relative to the beams. An inaccurate setup may result in not only recurrence of the tumour but also medical complications. The aim of the project is to develop a novel image processing system to enable fast and accurate evaluation of patient setup errors in radiotherapy by automatic detection and alignment of anatomical features in images acquired during treatment simulation and treatment delivery. By combining various image processing and mathematical techniques, the thesis presents the successful development of an effective approach which includes detection and separation of collimation features for establishment of image correspondence, region based image alignment based on local mutual information, and application of the least-squares method for exhaustive validation to reject outliers and for estimation of global optimum alignment. A complete software tool was developed and clinical validation was performed using both phantom and real radiotherapy images. For the former, the alignment accuracy is shown to be within 0.06 cm for translation and 1.14 degrees for rotation. More significantly, the translation is within the ±0.1 cm machine setup tolerance and the setup rotation can vary between ±1 degree. For the latter, the alignment was consistently found to be similar or better than those based on manual methods. Therefore, a good basis is formed for consistent, fast and reliable evaluation of patient setup errors in radiotherapy.
366

Advancing acoustography by multidimensional signal processing techniques

Bach, Michael January 2006 (has links)
The research presented in this thesis is the investigation into multidimensional signal processing for acoustography. Acoustography is a novel inspection technique similar to x-ray. However, instead of using hazardous ionising radiation, acoustography is based on sound. Inspection data are intensity images of the interior of components under inspection. Acoustography is a novel screening technique to inspect components without physically damaging them. Multidimensional signal processing refers to the processing of inspection data by signal and image processing techniques. The acoustographic imaging system is characterised with focus on signal and image processing. This system characterisation investigates into various degradations and image influencing properties. Signal and image processing techniques are then formally defined for the context of processing acoustographic data. The applicability of denoising and segmentation techniques is demonstrated. Filter primitives are demonstrated to be able to remove certain noise features. Particular focus rests on denoising and segmentation techniques based on physical analogy with diffusion. The diffusivity is locally controlled by data gradient measures. The diffusion technique using certain parameter settings performs the denoising of the inspection data without manipulating true image features. The same algorithm with a different parameter settings is employed to perform segmentation and thus separating fault features from background. Based on response characteristics of the acoustographic system, a data fusion algorithm has been developed to merge multiple observations into one datum, thereby increasing the dynamic range. The two stage algorithm consists of an iterative curve fitting algorithm followed by a reverse calculation using the curve parameter to yield a single observation. The algorithm has been improved further towards robustness to noise. Further, the fusion of denoised data is demonstrated. As a direct result of the work presented, future work is suggested to improve inferring from observation data to the state of the component under investigation. Further work is suggested to improve the understanding of the imaging system and inverse methods are proposed which take into account various particularities of the acoustographic system.
367

South Asian females and technology education : a study of engagement and disengagement in Britain

Mirza, Mehreen Naz January 2002 (has links)
My thesis is concerned with the engagement and disengagement of South Asian girls and women with technology education in Britain. The research arose out of the need to establish whether South Asian girls and women had been included in, and benefited from, the attempts to encourage more girls and women into the fields of science, engineering and technology. Existing theoretical, especially feminist, frameworks for understanding the experiences of girls and women in science, engineering and technology, were largely silent about the experiences of minority ethnic girls and women, especially those of South Asian heritage; their experiences and perspectives were subsumed under an assumed generic female experience, which I have termed 'universal wonian' syndrome. Similarly, existing theoretical discourses for understanding the specific experiences of South Asian girls and women in education and the labour market, were too broad in focus and unable to offer any commentary about their position in relation to specific subjects and/or occupations. My thesis is intended to make a contribution towards assessing whether the initiatives to proniote girls and women into technology are of relevance and applicability to South Asian girls and women. I adopted an 'anti-oppressive' epistemological and methodological framework within which to locate the research process, from initial conceptualisation to final data analysis. In particular I focused on anti-racist, feminist, and Black feminist epistemology and methodology. I utilised both quantitative and qualitative methods, within a reflexive framework for gathering and analysing data, in order to respond better to changing research circumstances.. My thesis is intended to make a contribution to the wider understanding of epistemological and methodological research issues, especially in terms of the applicability of anti-racist, feminist and Black feminist standpoint epistemology. It is intended to contribute especially to our knowledge about ethical concerns which researchers need to be cognisant of from the outset of their research project. Data was gathered and analysed by me using a grounded theory approach, which resulted in my use of a theoretical model proposed by Anthias and Yuval-Davis (1992). This theory is intended to examine the connections between gender and ethnicity in the process of nation-building, but I felt that it could also be used to explain the ways in which gender and ethnicity acted upon the South Asian girls and women in their choice of subject of study and subsequent jobs/occupations. The data analysis revealed that many of the initiatives to encourage girls and women into fields in which they were under-represented, had had very little, if any impact upon the subject and occupational choices of South Asian girls and women in this study, as those initiatives had focused on addressing primarily, if not exclusively gender issues, whereas the lives and decision-making processes of the South Asian girls and women were informed by the experience of a particularly ethnicised-gendered experience. Consequently the thesis moves beyond focusing exclusively on the ways in which South Asian girls and women make choices about technology education and occupations, to a concern with how they make choices about education and work in general, through negotiating with various discourses around questions of gender, ethnicity/race, class and religion.
368

Development and Testing of Passive Walking Assistive Exoskeleton with Upward Force Assist

Lovrenovic, Zlatko January 2017 (has links)
An aging population and rising prevalence in obesity, arthritis and diabetes are resulting in a great number of elders that are suffering from mobility challenges. Walking assist exoskeletons have the potential to help preserve mobility in elders. The most common type of exoskeleton relies on heavily, complex and expensive components to help their user walk effortlessly. Recent research on walking assist exoskeletons has shifted towards the creation of an entirely mechanical system called passive walking assist exoskeleton. This research aims to design, model and test a passive walking assist exoskeleton that reduces the felt weight of the user during gait. The assist is achieved by the action of a seat mechanism which constantly produces an upward force on the pelvis of the user. This thesis details the entire composition and assembly of such device. The proposed device was modelled in order to predict the assistance provided by the seat mechanism when standing and walking with the device. A human-sized prototype was built and tested in order to mechanically validate the proposed design. The test results validated the proposed seat mechanism which produces the desired upward force, but the use of the exoskeleton in its current state hindered the natural gait pattern of the user.
369

Tvorba distribučního centra / Formation of distribution centre

Kobliha, Marek January 2009 (has links)
The source of information for contemporary as well as future implementers of the distribution centre. Process of a strategic choice, over the decision whether to pursue an own or external distribution centre, an building proposal itself to the final implementation and operation. The key words - distribution, project, outsourcing, development, storage technologies, handling equipment, automatic identification, layout.
370

BIM i förvaltningsfasen : En studie om möjligheter i förvaltningsfasen av en byggnad med hjälp av en väl utförd informationsmodell / BIM in the management phase : A study of opportunities in the management phase of a building using a well-executed information model

Öhman, Erik January 2017 (has links)
BIM – byggnadsinformationsmodellering eller byggnadsinformationsmodeller är begrepp som idag känns igen av de flesta i byggbranschen och många är överens om vilken stor potential som finns med att använda denna nya teknik. Trots detta går implementeringen av det här nya arbetssättet trögt i branschen. Fortfarande används BIM som mest innan och under produktionen av nya byggnader och anläggningar medan den allra längsta tidsperioden i byggnadens livscykel glöms bort, nämligen förvaltningen av byggnaden. Nya byggnader har ofta en livslängd på över 100 år vilket gör att underhåll och reparationer kommer att vara nödvändiga för att upprätthålla de krav som finns på moderna byggnader. Med arbetssättet BIM med tillhörande modeller finns potential till att underlätta förvaltningen av byggnader. Idag finns en liten efterfrågan på väl utförda modeller från förvaltarsidan, de ser inte fördelarna med att ha en väl utförd informationsmodell och ställer därför inte särskilt stora krav på de olika modellerna. Syftet med examensarbetet är att ta reda på hur modeller som skapas i projekteringen och information i den kan användas i förvaltningsarbetet av byggnaden och att ta reda på vad projektörerna kan lägga till i modellerna som är till nytta i förvaltningsarbetet. För att ta reda på detta har dels en litteraturstudie gjorts för att förstå nödvändig teori och fakta samt ett referensobjekt granskats för att ta reda på vilket sätt BIM kommer att användas i just detta projekt. Referensobjektet som har använts i studien kallas Helios, en del av SCA:s nya massafabrik i Timrå utanför Sundsvall, har en detaljerad modell ritats upp för att sedan ta fram de nödvändiga 2D-ritningarna som används som underlag vid byggandet. Modellen innehåller däremot inte mer information än nödvändigt, eftersom få krav har ställts på den. Informationen är samlad i andra dokument och beskrivningar som används i produktion och förvaltning. Modellen som har byggts upp kan exporteras till så kallat IFC-format, vilket gör att modellen går att öppna i program som går att ladda hem gratis från internet. I dessa program kan användaren vrida och vända på modellen och titta närmare på detaljer. Det är också möjligt att koppla ihop dessa modeller med andra system, till exempel tabellerade värden i Microsoft Excel. Det gör att det går att få en exakt visuell bild av element i byggnaden samtidigt som ytterligare information kan läsas av i andra program. Det är möjligt för projektörer att lägga in mer information i modellerna. Som exempel kan nämnas länkar till produkters hemsidor, vilken typ av rostskyddsbehandling ett visst element har fått och vilken typ av brandskyddsmålning som konstruktionen behandlats med. I projektet Helios kommer begreppet BIM att gå förlorat när byggnaden går in i förvaltningsfasen eftersom modellen inte kommer att följa med som relationshandlingar. Det är platta ritningar med tillhörande beskrivningar som kommer att ligga till grund vid förvaltningsarbetet. Det här behöver inte betyda att BIM inte kan användas senare under byggnadens livscykel. Det går att rita upp byggnaden i efterhand även om inte all information om alla objekt finns representerade i modellen eller i tillhörande system. Men för att BIM ska kunna uppnå den potential som finns måste noggrannare krav ställas redan i projekteringsskedet. / BIM – building information modelling or building information model is a well known concept that most people in the construction industry is familiar with and agrees that there is a big potential with this new technology. Despite this, the implementation of this new approach is slow in the industry. Still, BIM is most used before and during the production of new buildings and facilities, while the longest period in a building's life cycle is forgotten, namely the management of the building. New buildings often have a lifespan of over 100 years, which means that maintenance and repairs will be necessary to maintain the requirements of modern buildings. There is potential to facilitate the management of buildings with well-executed information modeling. Today there is a small demand for these well-made models from the management companies and owners of the buildings, they commonly do not acknowledge the benefits of having a building information model to help with their daily work and therefore place no special demands on the various models.   The purpose of this thesis is to find out how information models can be used in the management work of the building and to find out what the projectors can add to the models that are useful in the management work. In order to find out, a literature study has been made to understand the necessary theory and facts and a reference object has been examined to find out how BIM will be used in this particular project. The reference object that was used in this thesis was Helios, a part of SCA's new pulp mill in Timrå, outside of Sundsvall, has a detailed model been drawn up and based on this model the necessary 2D drawings is produced and used as the basis for construction. The model does not contain more information than necessary, because few demands have been made on it. The information is gathered in other documents and descriptions used in the production and management. The model that has been drawn up can be exported to IFC format, which means that the model can be opened in the program that can be downloaded for free from the Internet. In these applications, the user can twist and turn the model and look at all details of the building. It is also possible to connect these models with other systems, for example, tabulated values in Microsoft Excel. This makes it possible to obtain an accurate visual representation of the elements of the building while further information can be read by other applications. It is possible for projectors to enter more information in the models. For example, there are links to products' websites, what kind of anti-corrosion treatment a particular element has received and what type of fire protection paint that has been used. The project Helios, the concept of BIM will be lost when the building goes into the management phase as this model will not follow. Flat drawings and a descriptions will be the basis for management work for about 100 years to come. This does not mean that BIM can not be used later in the building's life cycle. It is possible to make a model of the building afterwards, although not all information about all objects is represented in the model or in the associated system. However, in order for BIM to achieve the potential that exists, more requirements must be set in the design phase.

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