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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.
21

Towards a resilient networked service system

2013 June 1900 (has links)
Large service systems today are of highly network structures. In this thesis, these large service systems are called networked service systems. The network nature of these systems has no doubt brought mass customized services but has also created challenges in the management of their safety. The safety of service systems is an important issue due to their critical influences on the functioning of society. Traditional safety engineering methods focus on maintaining service systems in a safe state, in particular aiming to maintain systems to be reliable and robust. However, resilience cannot be absent from safety out of many recent disasters that occur in society. The goal of this thesis is to improve the resilience of networked service systems. Four major works have been performed to achieve this goal. First, a unified definition of service systems was proposed and its relationship to other system concepts was unfolded. Upon the new definition, a domain model of service systems was established by a FCBPSS framework, followed by developing a computational model. Second, a definition of resilience for service systems was proposed, based on which the relationship among three safety properties (i.e., reliability, robustness and resilience) was clarified, followed by developing a framework for resilience analysis. Third, a methodology of resilience measurement for service systems was proposed by four measurement axioms along with corresponding mathematical models. The methodology focused on the potential ability of a service system to create optimal rebalancing solutions. Two typical service systems, transportation system and enterprise information system, were employed to validate the methodology. Fourth, a methodology of enhancing resilience for service systems was proposed by integrating three types of reconfigurations of systems, namely design, planning and management, along with the corresponding mathematical model. This methodology was validated by an example of transportation system. Several conclusions can be drawn from the work above: (1) a service system has a unique characteristic that it meets humans' demand directly, and its safety relies on the balance between the supplies and demands; (2) different from reliability and robustness, the resilience of a service system focuses on the rebalancing ability from imbalanced situations; (3) it makes sense to measure the resilience of a service system only for a particular imbalanced situation and based on evaluation of rebalancing solutions; and (4) integration of design, planning and management is an effective approach for improvement of the resilience for a service system. The contributions of this thesis can be summarized. Scientifically, this thesis work has improved our understanding of service systems and their resilience property; furthermore, this work has advanced the state of knowledge of safety science in particular having successfully responded to two questions: is a service system safe and how to make a service system safer? Technologically or methodologically, the work has advanced the knowledge for modeling and optimization of networked service systems in particular with multiple layer models along with the algorithms for integrated decision making on design, planning, and management.
22

Resilient Modulus and Strength Index Properties of Stabilized Base for Tennessee Highways

MacDonald, Wesley M 01 May 2008 (has links)
Typical material used by the Tennessee Department of Transportation for highway bases was evaluated for application to the new Mechanistic-Empirical Pavement Design Guide. Two types of granular Tennessee highway base material were mixed with different stabilizers and tested in the lab according to AASHTO T-307 99 (2003). Unconfined Compressive Strength and California Bearing Ratio tests were also done in an effort to correlate these results with resilient modulus. Three different combinations of base and stabilizer were tested and modeling coefficients were produced. Base structural layer coefficients were generated and compared to coefficients currently in use by TDOT.
23

An investigation into resilient fire engineering building design

Wilkinson, Peter January 2013 (has links)
As an engineering discipline within the United Kingdom, fire engineering is relatively young. It has been accepted as an alternative to traditional prescriptive means of meeting the functional requirements of the Building Regulations since the publication of the 1985 edition of Approved Document B, which was one of a series issued to provide practical guidance on the requirements of the Building Regulations for England and Wales. It deals specifically with fire safety requirements for building work. Performance-based fire engineering design methods have facilitated architectural design freedoms and supported creative construction. This research has established that for a successful and holistic fire engineering strategy to be developed; The end-user client should describe from the outset what they want their building or facility to achieve, and there should be an agreed process for this to happen; Commercial property insurers should be consulted and exploited as a useful and intelligent resource to the design team; and Fire engineering practitioners should fulfil their role as advisers to the architect, or building design team, in order to achieve the agreed objectives. However, it has become evident that since fire engineering has become more established, it is clear that we are far from this ideal situation. Significant concerns have been raised regarding various elements of the design process including the ability to consider aspects other than life safety. Within this discourse, the author has outlined their research investigating how performance-based fire engineering techniques are used within building design. The literature review explores key concepts of fire engineering including definitions and benefits etc., and also describes concerns regarding the motivations for applying fire engineering techniques to building design. Survey-based research suggests that greater input is required from commercial property insurers at the building design stage in order to champion property protection and business resilience objectives. A case-study investigation, however, concluded that for a number of reasons, it is impractical to expect the insurer to influence the design team to the extent desired. Therefore, in response to these various research activities, the concept of business impact analysis has been introduced and developed by the author to ensure that property protection and business continuity objectives are at the forefront of new building design, whether the insurer is involved in the process or not. In order to help consulting fire engineers and architectural design teams incorporate business protection objectives in their fire safety designs, there is a requirement for the established British Standard, which defines a fire engineering procedure, to be enhanced. The author was instrumental in acquiring support from the Technical Committee within BSI responsible for maintaining the Standard, and PD 7974-8 Application of fire safety engineering principles to the design of buildings- Part 8: Property protection, mission continuity and resilience (British Standards institution, 2012) has been developed and published, led by the author. This significant new Standard embeds the use of a business impact analysis as an integral part of the qualitative design review process. Without following the BIA process as described in the draft document PD7974-8, business resilience objectives may be missed within the building design phase, allowing an inferior package of fire protection measures to be incorporated into building developments. For the first time, this new document will enable the building designer to be fully cognisant of their client's critical processes and the resources required to support these processes. It will therefore enable the appropriate fire safety measures to be incorporated into the building design to enhance business resilience. Initial evaluations of this guide though various stakeholder dissemination activities and a public consultation process has been positive. The potential concerns that the evaluations have raised regarding the role of the fire engineer throughout the building design phase, and regarding the prevalence of BIA within organisations will be addressed in the guide and the way it is publicised upon its launch.
24

Efficient transmission of error resilient H.264 video over wireless links

Connie, Ashfiqua Tahseen 11 1900 (has links)
With the advent of telecommunication technology, the need to transport multimedia content is increasing day by day. Successful video transmission over the wireless network faces a lot of challenges because of the limited resource and error prone nature of the wireless environment. To deal with these two challenges, not only the video needs to be compressed very efficiently but also the compression scheme needs to provide some error resilient features to deal with the high packet loss probability. In this thesis, we have worked with the H.264/ Advanced Video Coding (AVC) video compression standard since this is the most recent and most efficient video compression scheme. Also H.264 provides novel error resilient features e.g. slicing of the frame, Flexible Macroblock Ordering (FMO), data partitioning etc. In this thesis, we investigate how to utilize the error resilient schemes of H.264 to ensure a good quality picture at the receiving end. In the first part of the thesis, we find the optimum slice size that will enhance the quality of video transmission in a 3G environment. In the second part, we jointly optimize the data partitioning property and partial reliability extension property of the new transport layer protocol, Stream Control Transmission Protocol (SCTP). In the third and last part, we focus more on the network layer issues. We obtain the optimum point of application layer Forward Error Correction (FEC) and Medium Access Control (MAC) layer retransmission in a capacity constrained network. We assume that the bit rate assigned for the video application is more than the video bit rate so that the extra capacity available can be used for error correction.
25

Design methodologies for robust low-power digital systems under static and dynamic variations

Chae, Kwanyeob 27 August 2014 (has links)
Variability affects the performance and power of a circuit. Along with static variations, dynamic variations, which occur during chip operation, necessitate a safety margin. The safety margin makes it difficult to meet the target performance within a limited power budget. This research explores methodologies to minimize the safety margin, thereby improving the energy efficiency of a system. The safety margin can be reduced by either minimizing the variation or adapting to the variation. This research explores three different methods to compensate for variations efficiently. First, post-silicon tuning methods for minimizing variations in 3D ICs are presented. Design methodologies to apply adaptive voltage scaling and adaptive body biasing to 3D ICs and the associated circuit techniques are explored. Second, non-design-intrusive circuit techniques are proposed for adaptation to dynamic variations. This work includes adaptive clock modulation and bias-voltage generation techniques. Third, design-intrusive methods to eliminate the safety margin are proposed. The proposed methodologies can prevent timing-errors in advance with a minimized performance penalty. As a result, the methods presented in this thesis minimize static variations and adapt to dynamic variations, thereby, enabling robust low-power operation of digital systems.
26

REds: bemagtiging van lewensoriëteringonderwysers in Sasolburg wat deur MIV/VIGS geaffekteer word / Catharina Elizabeth Baker.

Baker, Catharina Elizabeth January 2009 (has links)
The negative impact of HIV/Aids, internationally and nationally; as well as on the education system of South Africa, is well-documented and cannot be ignored. The latest statistics indicate that South Africa currently has the highest occurrence of HIV/Aids in the world. Due to this high occurrence of HIV/Aids infected people, an unbelievably high percentage of the community is affected by the pandemic. Teachers, specifically life orientation teachers, are also affected by this phenomenon. All teachers, but specifically Life orientation teachers, are faced on a daily basis with various personal and professional challenges related to the HIV/Aids pandemic. These challenges threaten the well-being of teachers, so that researchers have been asked to empower teachers so that they can resist these challenges. A resilient teacher avails of the correct information on HIV/Aids and can therefore contribute to fighting the pandemic by providing correct information. This teacher will, amongst others, also have strong faith, the ability to discuss the pandemic openly and to obtain access to counselling. This resilient teacher realises the importance of a positive attitude despite the fact that she is realistic about the impact of the pandemic, has positive relationships and realises the value of support. The aim of my study was to determine the degree to which the programme Resilient Educators (REds) can support life orientation teachers who are affected by HIV/Aids, so that they will be equipped to resiliently withstand the challenges HIV/Aids set them. REds has been evaluated many times, but until the present, participants have not been life orientation teachers. In response to this aim, I followed a pre-experimental research design in the course of my study with twelve affected life orientation teachers in Sasolburg, as participants. Before beginning with the programme, a pretest (qualitative as well as quantitative data were collected) was done. Intervention took place over seven weeks by means of the REds programme. I wrote a reflection journal during the intervention and asked participants to report their impressions of the sessions in writing. After completing the programme, a post test was written (qualitative as well as quantitative data were collected) to determine the degree to which participants were able to withstand the challenges of HIV/Aids more resiliently. Thorough analysis of the pre and post test data, as well as the reflection data, creates the impression that participants were already resilient to some degree before joining the programme, but after completing the programme, their resilience can be described as more profound than before, and this fact can largely be ascribed to the effectiveness of the REds programme. / Thesis (M.Ed. (Educational Psychology))--North-West University, Vaal Triangle Campus, 2010.
27

REds: bemagtiging van lewensoriëteringonderwysers in Sasolburg wat deur MIV/VIGS geaffekteer word / Catharina Elizabeth Baker.

Baker, Catharina Elizabeth January 2009 (has links)
The negative impact of HIV/Aids, internationally and nationally; as well as on the education system of South Africa, is well-documented and cannot be ignored. The latest statistics indicate that South Africa currently has the highest occurrence of HIV/Aids in the world. Due to this high occurrence of HIV/Aids infected people, an unbelievably high percentage of the community is affected by the pandemic. Teachers, specifically life orientation teachers, are also affected by this phenomenon. All teachers, but specifically Life orientation teachers, are faced on a daily basis with various personal and professional challenges related to the HIV/Aids pandemic. These challenges threaten the well-being of teachers, so that researchers have been asked to empower teachers so that they can resist these challenges. A resilient teacher avails of the correct information on HIV/Aids and can therefore contribute to fighting the pandemic by providing correct information. This teacher will, amongst others, also have strong faith, the ability to discuss the pandemic openly and to obtain access to counselling. This resilient teacher realises the importance of a positive attitude despite the fact that she is realistic about the impact of the pandemic, has positive relationships and realises the value of support. The aim of my study was to determine the degree to which the programme Resilient Educators (REds) can support life orientation teachers who are affected by HIV/Aids, so that they will be equipped to resiliently withstand the challenges HIV/Aids set them. REds has been evaluated many times, but until the present, participants have not been life orientation teachers. In response to this aim, I followed a pre-experimental research design in the course of my study with twelve affected life orientation teachers in Sasolburg, as participants. Before beginning with the programme, a pretest (qualitative as well as quantitative data were collected) was done. Intervention took place over seven weeks by means of the REds programme. I wrote a reflection journal during the intervention and asked participants to report their impressions of the sessions in writing. After completing the programme, a post test was written (qualitative as well as quantitative data were collected) to determine the degree to which participants were able to withstand the challenges of HIV/Aids more resiliently. Thorough analysis of the pre and post test data, as well as the reflection data, creates the impression that participants were already resilient to some degree before joining the programme, but after completing the programme, their resilience can be described as more profound than before, and this fact can largely be ascribed to the effectiveness of the REds programme. / Thesis (M.Ed. (Educational Psychology))--North-West University, Vaal Triangle Campus, 2010.
28

Efficient transmission of error resilient H.264 video over wireless links

Connie, Ashfiqua Tahseen 11 1900 (has links)
With the advent of telecommunication technology, the need to transport multimedia content is increasing day by day. Successful video transmission over the wireless network faces a lot of challenges because of the limited resource and error prone nature of the wireless environment. To deal with these two challenges, not only the video needs to be compressed very efficiently but also the compression scheme needs to provide some error resilient features to deal with the high packet loss probability. In this thesis, we have worked with the H.264/ Advanced Video Coding (AVC) video compression standard since this is the most recent and most efficient video compression scheme. Also H.264 provides novel error resilient features e.g. slicing of the frame, Flexible Macroblock Ordering (FMO), data partitioning etc. In this thesis, we investigate how to utilize the error resilient schemes of H.264 to ensure a good quality picture at the receiving end. In the first part of the thesis, we find the optimum slice size that will enhance the quality of video transmission in a 3G environment. In the second part, we jointly optimize the data partitioning property and partial reliability extension property of the new transport layer protocol, Stream Control Transmission Protocol (SCTP). In the third and last part, we focus more on the network layer issues. We obtain the optimum point of application layer Forward Error Correction (FEC) and Medium Access Control (MAC) layer retransmission in a capacity constrained network. We assume that the bit rate assigned for the video application is more than the video bit rate so that the extra capacity available can be used for error correction.
29

Resilient cities: an analysis of resilient urban form

Aguilar, Johnny R. 07 January 2016 (has links)
This thesis studies the theories, scientific evidence and spatial relationships within urban form to determine means and deviations that developments can use to determine the resiliency of urban form within a given location. Resiliency within urban form functions as modulations around a morphological mean. Rather than replicate the mean, resilient cities modulate with low standard deviations around the mean. As a result, while many look aesthetically different, resilient cities are structurally more similar than dissimilar. Cities can use this information to inform their projects on a schematic design level to determine if they are improving their urban form or if they are deviating from the resilient mean.
30

Segmentação de imagens utilizando combinação de modelos de misturas Gaussianas

Silva, Styve Stallone da 28 February 2014 (has links)
Submitted by Luiz Felipe Barbosa (luiz.fbabreu2@ufpe.br) on 2015-03-10T19:06:02Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Styve Stallone da Silva.pdf: 3737470 bytes, checksum: 8b378e7a672e171ffc58dd1435b637ec (MD5) / Approved for entry into archive by Daniella Sodre (daniella.sodre@ufpe.br) on 2015-03-10T19:43:01Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Styve Stallone da Silva.pdf: 3737470 bytes, checksum: 8b378e7a672e171ffc58dd1435b637ec (MD5) / Made available in DSpace on 2015-03-10T19:43:01Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Styve Stallone da Silva.pdf: 3737470 bytes, checksum: 8b378e7a672e171ffc58dd1435b637ec (MD5) Previous issue date: 2014-02-28 / A segmentação de imagens tem por objetivo separar os objetos de interesse de determinado estudo em uma imagem. A segmentação da imagem deve parar quando os objetos procurados tiverem sido isolados. Por exemplo, na segmentação de uma imagem de transito, onde se deseja identificar as placas dos carros, é necessário segmentar a imagem separando todos os carros do restante da imagem, e ainda separar as placas dos carros para realizar o processo de identificação de cada placa. O processo de segmentação de imagens tem grande importância na análise e descrição de imagens, pois essa divisão, realizada na imagem, é responsável pelo sucesso de outras técnicas como detecção de pessoas e reconhecimento de faces. Atualmente, métodos de segmentação do campo de jogo em vídeos de futebol têm sido bastante explorados. O interesse em analisar e classificar eventos em vídeos, além das dificuldades atreladas às variações de clima e iluminação que se refletem na segmentação de campo, tem gerado grande interesse em desenvolver métodos que consigam realizar a segmentação mesmo com os problemas anteriormente citados. A segmentação do campo é o passo fundamental para a análise de diversos tipos de eventos em um vídeo de jogo de futebol, que podem ser detectados e classificados automaticamente, como gols, faltas e escanteios. Muitos métodos de segmentação de campo têm utilizado apenas as características das cores do gramado, porém as tonalidades dessas cores variam, evidenciando fraquezes desses métodos. O trabalho apresentado propõe um método de segmentação baseado em combinação de misturas gaussianas e rede neural, utilizando características de cores e também características de texturas da imagem. O referido método é composto pelas etapas de extração de características, agrupamento dos dados, segmentação, classificação e pósprocessamento. Como métricas de comparação de resultados são utilizadas curvas receiver operating characteristic (ROC) e taxas de verdadeiros e falsos positivos. Os resultados do modelo proposto são comparados a modelos gaussianos únicos, algoritmo k-Nearest Neighbor (k-NN) e ao algoritmo Fuzzy C-means (FCM), apresentando resultado de 94,25% de acerto para testes com diversas variações climáticas e de iluminação. O resultado foi superior aos outros algoritmos analisados.

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