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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.
71

Elastic wave attenuation, dispersion and anisotropy in fractured porous media

Galvin, Robert January 2007 (has links)
Development of a hydrocarbon reservoir requires information about the type of fluid that saturates the pore space, and the permeability distribution that determines how the fluid can be extracted. The presence of fractures in a reservoir can be useful for obtaining this information. The main objectives of this thesis are to investigate how fracturing can be detected remotely using exploration seismology. Fracturing will effect seismic data in a number of ways. Firstly, if the fractures are aligned preferentially in some direction, the medium will exhibit long wavelength anisotropy. In turn, if wave propagation is not aligned with one of the symmetry axes of the effective medium then shear wave splitting will depend upon the properties of the fracture filling fluid. Secondly, elastic waves will experience attenuation and dispersion due to scattering and wave-induced fluid flow between the fractures and matrix porosity. This occurs because the fractures are more compliant than the background medium and therefore there will be a pressure gradient formed during passage of the wave, causing fluid to flow between fractures and background. If the direction of shear-wave propagation is not perpendicular or parallel to the plane of fracturing, the wave polarized in the plane perpendicular to the fractures is a quasi-shear mode, and therefore the shear-wave splitting will be sensitive to the fluid bulk modulus. / The magnitude of this sensitivity depends upon the extent to which fluid pressure can equilibrate between pores and fractures during the period of the deformation. In this thesis I use the anisotropic Gassmann equations and existing formulations for the excess compliance due to fracturing to estimate the splitting of vertically propagating shear-waves as a function of the fluid modulus for a porous medium with a single set of dipping fractures and with two conjugate fracture sets dipping with opposite dips to the vertical. This is achieved using two alternative approaches. In the first approach it is assumed that the deformation taking place is quasi-static. That is, the frequency of the elastic disturbance is low enough to allow enough time for fluid to flow between both the fractures and the pore space throughout the medium. In the second approach I assume that the frequency is low enough to allow fluid flow between a fracture set and the surrounding pore space, but high enough so that there is not enough time during the period of the elastic disturbance for fluid flow between different fracture sets to occur. It is found that the second approach yields a much stronger dependency of shear-wave splitting on the fluid modulus than the first one. This is a consequence of the fact that at higher wave frequencies there is not enough time for fluid pressure to equilibrate and therefore the elastic properties of the fluid have a greater effect on the magnitude of the shear-wave splitting. I conclude that the dependency of the shear-wave splitting on the fluid bulk modulus will be at its minimum for quasi-static deformations, and will increase with increasing wave frequency. / In order to treat the problem of dispersion and attenuation due to wave-induced fluid flow I consider interaction of a normally incident time-harmonic longitudinal plane wave with a circular crack imbedded in a porous medium governed by Biot’s equations of dynamic poroelasticity. The problem is formulated in cylindrical coordinates as a system of dual integral equations for the Hankel transform of the wave field, which is then reduced to a single Fredholm integral equation of the second kind. It is found that the scattering that takes place is predominantly due to wave induced fluid flow between the pores and the crack. The scattering magnitude depends on the size of the crack relative to the slow wave wavelength and has its maximum value when they are of the same order. I conclude that this poroelastic effect should not be neglected, at least at seismic frequencies. Using the solution of the scattering problem for a single crack and multiple-scattering theory I estimate the attenuation and dispersion of elastic waves taking place in a porous medium containing a sparse distribution of such cracks. I obtain from this analysis an effective velocity which at low frequencies reduces to the known static Gassmann result and a characteristic attenuation peak at the frequency such that the crack size and the slow wave wavelength are of the same order. / When comparing with a similar model in which multiple scattering effects are neglected I and that there is agreement at high frequencies and discrepancies at low frequencies. I conclude that the interaction between cracks should not be neglected at low frequencies, even in the limit of weak crack density. Since the models only agree with each other at high frequencies, when the time available for fluid diffusion is small, I conclude that the interaction between cracks that takes place as a result of fluid diffusion is negligible at high frequencies. I also compare my results with a model for spherical inclusions and find that the attenuation for spherical inclusions has exactly the same dependence upon frequency, but a difference in magnitude that depends upon frequency. Since the attenuation curves are very close at low frequencies I conclude that the effective medium properties are not sensitive to the shape of an inclusion at wavelengths that are large compared to the inclusion size. However at frequencies such that the wavelength is comparable to or smaller than the inclusion size the effective properties are sensitive to the greater compliance of the flat cracks, and more attenuation occurs at a given frequency as a result.
72

Vårdplanering och stödinsatser : En studie av kontaktpersonalens arbete på två trapphusboenden i Eskilstuna kommun.

Gellerstedt, Elena January 2005 (has links)
<p>Syftet med denna studie har varit att utvärdera och jämföra vårdplaneringsarbetet och de stödinsatser som har gjorts utifrån de målstyrda insatsplanerna på två trapphusboenden inom Eskilstuna kommun. Underlaget till studien har baserats på innehållet i skriftliga vårdplaner tillsammans med data från 14 stycken intervjuer med vårdpersonalen. Behovsområdena i Camberwells behovsskattningsskala (CAN; Camberwells Assessment of Need) har används som gemensamma kriterier att jämföra intervjuerna och de två trapphusboendenas vårdplaner mot. Studien visar att personalen på det ena trapphusboendet täcker av fler behovsområden enligt CAN i de skriftliga vårdplanerna, lyckas förmedla sin syn på brukarnas behov i dem samt använder sig av evidensbaserade metoder i vårdarbetet i större utsträckning jämfört med personalen på det andra boendet. Även synpunkter och tillvägagångssätt skiljer sig åt mellan de två personalgrupperna med avseende på hur de går tillväga vid upprättandet av en skriftlig vårdplan, hur de tolkar begreppet brukardelaktighet samt vilket stöd personalen anser sig få i arbetet. Båda personalgrupperna betonar relationens betydelse i vårdarbetet och efterlyser ett bättre samarbete med andra berörda instanser. I resultatet framgår att systematiska utvärderingar knappast förekommer och att psykologiska besvär tycks vara ett behovsområde som i alltför hög grad förbises vid vårdplanering trots att det uppmärksammas av både personal och brukare.</p>
73

Liten displaymodul

Jonsson, Michael January 2006 (has links)
<p>The purpose of this Master Thesis is to analyze what suitable hardware platforms there are on the market in order to build a low price control and information system for mobile applications, called small display module. The thesis will be underlying material for making a decision for further development. The result of the thesis consists mainly of a Windows CE kernel and a schematic for a CPU card, on which it would be suitable to build the display module. Another major part of the report is the introduction of different techniques that could be of interest when designing a processor based system. The processor architecture that was chosen is the x86. This is mainly due to CPU availability, but as well as the fact that existing software can be used on the display module without any significant modifications. Many interesting processors were sorted out because they hade a very high price on the development kits from the manufacturer and because the possible production volume can not manage this cost. The development kit makes the development easier and can be used for performance tests before prototypes are built.</p>
74

Combining the Good Things from Vehicle Networks and High-Performance Networks

Armide, Misikir, Ecker, Herbert January 2007 (has links)
<p>The aim of this Master’s thesis is to develop a solution for combining speed and performance of switched Ethernet with the real time capability and determinism of sophisticated in- vehicle networks. After thorough research in vehicle network standards, their demands and features, the</p><p>Flexible Time Division Multiple Access (FTDMA) protocol of FlexRay was chosen to be applied on a switched Ethernet architecture since it can accommodate both hard real time tasks and soft real time tasks. To provide hard real time capability, what this paper focuses on, a media access method was developed by creating static TDMA schedules for each node’s sending and receiving</p><p>port according to a certain traffic assumption. To validate the developed media access algorithm several examples with different traffic assumptions and architectures were generated and</p><p>investigated based on their sending and receiving utilization. A second method for validating and thus proving the functionality of the algorithm was by simulation. Therefore the Matlab Simulink</p><p>media library extension TRUE TIME was used to simulate a simple example with 100% sending and receiving utilization for each node.</p>
75

Motorsimulering av CAN-buss : Boxcar 9-5

Richardson, Malin, Sandell, Unn January 2003 (has links)
No description available.
76

CAN bus diagnostic tool for PocketPC

Pettersson, Marcus January 2002 (has links)
No description available.
77

Utveckling av en provmetod för ett CAN-baserat nätverk

Skopo, Aldijana, Börnstedt, Mattias January 2004 (has links)
No description available.
78

Utvecklingsverktyg för analys av fordonsrelaterade diagnosprotokoll

Johansson, Henrik, Fransson, Christian January 2004 (has links)
No description available.
79

Vårdplanering och stödinsatser : En studie av kontaktpersonalens arbete på två trapphusboenden i Eskilstuna kommun.

Gellerstedt, Elena January 2005 (has links)
Syftet med denna studie har varit att utvärdera och jämföra vårdplaneringsarbetet och de stödinsatser som har gjorts utifrån de målstyrda insatsplanerna på två trapphusboenden inom Eskilstuna kommun. Underlaget till studien har baserats på innehållet i skriftliga vårdplaner tillsammans med data från 14 stycken intervjuer med vårdpersonalen. Behovsområdena i Camberwells behovsskattningsskala (CAN; Camberwells Assessment of Need) har används som gemensamma kriterier att jämföra intervjuerna och de två trapphusboendenas vårdplaner mot. Studien visar att personalen på det ena trapphusboendet täcker av fler behovsområden enligt CAN i de skriftliga vårdplanerna, lyckas förmedla sin syn på brukarnas behov i dem samt använder sig av evidensbaserade metoder i vårdarbetet i större utsträckning jämfört med personalen på det andra boendet. Även synpunkter och tillvägagångssätt skiljer sig åt mellan de två personalgrupperna med avseende på hur de går tillväga vid upprättandet av en skriftlig vårdplan, hur de tolkar begreppet brukardelaktighet samt vilket stöd personalen anser sig få i arbetet. Båda personalgrupperna betonar relationens betydelse i vårdarbetet och efterlyser ett bättre samarbete med andra berörda instanser. I resultatet framgår att systematiska utvärderingar knappast förekommer och att psykologiska besvär tycks vara ett behovsområde som i alltför hög grad förbises vid vårdplanering trots att det uppmärksammas av både personal och brukare.
80

Architecture for a remote diagnosis system used in heavy-duty vehicles

Björkman, Anders January 2008 (has links)
The diagnosis system of a Scania vehicle is an indispensable tool for workshop personnel and engineers in their work. Today Scania has a system for fetching diagnostic information from field test vehicles remotely and store them in a database, so called remote diagnosis. This saves the engineers much time by not having to visit every vehicle. The system uses a Windows based on-board PC in the vehicle called an Interactor. The Interactor has a telematic unit for communication with Scanias Fleet Management System and the CAN-bus in the vehicle. In the next generation of the Interactor, its telematic unit is to be replaced by a Linux based telematic unit called the Communicator 200 (C200). The purpose of this master project is to create a new architecture for a remote diagnosis system that uses the new telematic unit Communicator 200. <br />The thesis gives an analysis of the current remote diagnosis system used at Scania and proposes an architecture for a new generation remote diagnosis system using the C200. Also a system for demonstrating how to perform remote diagnosis over the C200 has been built. The thesis describes the operation and how the demonstration system was implemented.

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