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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.
141

On-chip Power Grid Verification with Reduced Order Modeling

Goyal, Ankit 31 December 2010 (has links)
To ensure the robustness of an integrated circuit design, its power distribution network (PDN) must be validated beforehand against any voltage drop on VDD nets. However, due to the increasing size of PDNs, it is becoming difficult to verify them in a reasonable amount of time. Lately, much work has been done to develop Model Order Reduction (MOR) techniques to reduce the size of power grids but their focus is more on simulation. In verification, we are concerned about the safety of nodes, including the ones which have been eliminated in the reduction process. This work proposes a novel approach to systematically reduce the power grid and accurately compute an upper bound on the voltage drops at power grid nodes which are retained. Furthermore, a criterion for the safety of nodes which are removed is established based on the safety of other nearby nodes and a user specified margin.
142

Geomechanical analysis of caprock integrity

Soltanzadeh, Hamidreza 10 September 2009
To safely store carbon dioxide in enhanced oil recovery/ CO2 sequestration projects it is important to ensure the integrity of the caprock during and after production and injection. A change in fluid pressure and temperature within a porous reservoir will generally induce stress changes within the reservoir and the rocks that surround it. Amongst the potential hazards resulting from these induced stress changes is the reactivation of existing faults or fractures and inducing new fractures, which may breach the hydraulic integrity of the caprock that bounds the reservoir.<p> The theories of inclusions and inhomogeneities have been used in this research to derive semi-analytical and closed-form solutions for induced stress change during pore pressure change within a reservoir and in the surrounding rock, under plane strain and axisymmetric conditions. Methods have been developed to assess fault reactivation and induced fracturing during injection or production within a reservoir. The failure stress change concept for a Coulomb failure criterion has been used to study the likelihood of fault reactivation and induced fracturing within the reservoir. Formulations have been adopted to calculate the critical pressure change for fault reactivation and induced fracturing within the reservoir and in the surrounding rock during injection and production. Sensitivity analysis has been performed to study the effects of different parameters such as initial in-situ stress, reservoir geometry, reservoir depth, reservoir tilt or dip , material property contrast between the reservoir and surrounding rock, fault geometry, fault strength, and intact rock strength. General patterns of induced stress change, in-situ stress evolution, fault reactivation, and induced fracturing have been identified.<p> The developed methodologies have been applied to six different case studies: fault reactivation analysis in the entire field for a synthetic case study; induced fracturing analysis in the entire field in a synthetic case study; fault reactivation and induced stress change analysis within the Ekofisk oil reservoir in North Sea; fault reactivation analysis in the Lacq gas reservoir in France; the Weyburn-Midale EOR/CO2 Storage project in southeast Saskatchewan; and acid gas injection in Zama oil field, Alberta. The results of these case studies show good consistency with field observation, and physical and numerical models.<p> The generality, simplicity, and straightforwardness of the developed methodologies, along with their flexibility to model different plausible scenarios and their ease of implementation for systematic sensitivity analyses makes them suitable for decision-making and uncertainty management, specifically in early stages of reservoir development or site assessment for geological sequestration of carbon dioxide.
143

Replication, Security, and Integrity of Outsourced Data in Cloud Computing Systems

Barsoum, Ayad Fekry 14 February 2013 (has links)
In the current era of digital world, the amount of sensitive data produced by many organizations is outpacing their storage ability. The management of such huge amount of data is quite expensive due to the requirements of high storage capacity and qualified personnel. Storage-as-a-Service (SaaS) offered by cloud service providers (CSPs) is a paid facility that enables organizations to outsource their data to be stored on remote servers. Thus, SaaS reduces the maintenance cost and mitigates the burden of large local data storage at the organization's end. For an increased level of scalability, availability and durability, some customers may want their data to be replicated on multiple servers across multiple data centers. The more copies the CSP is asked to store, the more fees the customers are charged. Therefore, customers need to have a strong guarantee that the CSP is storing all data copies that are agreed upon in the service contract, and these copies remain intact. In this thesis we address the problem of creating multiple copies of a data file and verifying those copies stored on untrusted cloud servers. We propose a pairing-based provable multi-copy data possession (PB-PMDP) scheme, which provides an evidence that all outsourced copies are actually stored and remain intact. Moreover, it allows authorized users (i.e., those who have the right to access the owner's file) to seamlessly access the file copies stored by the CSP, and supports public verifiability. We then direct our study to the dynamic behavior of outsourced data, where the data owner is capable of not only archiving and accessing the data copies stored by the CSP, but also updating and scaling (using block operations: modification, insertion, deletion, and append) these copies on the remote servers. We propose a new map-based provable multi-copy dynamic data possession (MB-PMDDP) scheme that verifies the intactness and consistency of outsourced dynamic multiple data copies. To the best of our knowledge, the proposed scheme is the first to verify the integrity of multiple copies of dynamic data over untrusted cloud servers. As a complementary line of research, we consider protecting the CSP from a dishonest owner, who attempts to get illegal compensations by falsely claiming data corruption over cloud servers. We propose a new cloud-based storage scheme that allows the data owner to benefit from the facilities offered by the CSP and enables mutual trust between them. In addition, the proposed scheme ensures that authorized users receive the latest version of the outsourced data, and enables the owner to grant or revoke access to the data stored by cloud servers.
144

The Effect of Cement Mechanical Properties and Reservoir Compaction on HPHT Well Integrity

Yuan, Zhaoguang 14 March 2013 (has links)
In the life of a well, the cement sheath not only provides zonal isolation but also supports casing and increases casing-collapse resistance. Due to the high-pressure, high-temperature (HPHT) conditions, the cement sheath plays an important role in maintaining wellbore integrity. During the production process in HPHT wells, the pressure differential inside the casing and the surrounding formation is larger than the conventional wells. The stress induced by fluid withdrawal in highly compact reservoirs can cause the cement and the casing failure in these wells. These present a greater challenge to the wellbore integrity than the conventional wells. To have reliable data, extensive experimental work on Class G cement was carried out to measure the principal parameters for mechanical structural calculations. The experiment was also set up to simulate conditions under which cement low-cycle fatigue failure could occur. Zero-based cyclic pressure was applied to the casing in the cement low-cycle fatigue test. Three types of cement (72-lbm/ft3, 101-lbm/ft3 and 118-lbm/ft3) were cured and tested at 300ºF to study the cement mechanical properties under high-temperature conditions over the long term. The tests included a 1-year mechanical properties measurement such as compressive strength development; i.e., Young’s modulus and Poisson’s ratio. Finite element methods (FEM) were used to study the casing buckling deformation characteristics of reservoir compaction in some south Texas wells. The 2D and 3D FEM models were built to study the effects of mechanical properties and reservoir compaction on HPHT well integrity. As the confining pressure increases, the cement shows more plasticity and can withstand more pressure cycles. The cement with a higher Poisson’s ratio and lower Young’s modulus showed better low-cycle fatigue behavior. Casing collapse resistance is very sensitive to void location, cement Poisson’s ratio, cement Young’s modulus, and pore pressure. Casing eccentricity and voids shape have minor effect on the casing-collapse resistance. Casing shear failure, tension failure, and buckling failure are the most likely failure modes in reservoir compaction. For different casing wall thickness, the critical buckling strain is almost identical. This study presents a better understanding of casing failure and cement failure in HPHT wells. The results of the study will help improve cement and casing design to maintain wellbore integrity that can in turn be expected to extend throughout the life of the well.
145

GNSS performance modelling for high interrity aircraft applications

Shao, Liang 01 1900 (has links)
Till recently, no significant attempts have been made of developing Aircraft Based Augmentation System (ABAS) architectures capable of generating integrity signals suitable for safety-critical GNSS applications and no commercial ABAS products are available at present. The aim of this research is to support the design a system that generates integrity signals suitable for GNSS application. The conceptual design and key mathematical models were recently developed by the Italian Air Force Experimental Flight Test Centre (CSV-RSV) [1, 2]. Such a system, would be able to provide steering information to the pilot, allowing for real-time and continuous integrity monitoring, avoidance of safety/mission-critical flight conditions and fast recovery of the required navigation performance in case of GNSS data losses. The key elements addressed in this thesis are the development of a CATIA model for military and civil aircraft, supporting antenna obscuration and multipath analysis. This is to allow the ABAS system to generate suitable integrity flags when satellites signals are lost. In order to analyse the GNSS signal loss causes, the GNSS constellation models, the flight dynamics models, fading models, multipath models, Doppler shift models, and GNSS receiver tracking technology previously developed by CSV-RSV, are considered in this research.
146

Evaluating Treatment Acceptability, Treatment Integrity, and Cultural Modifications of a Bullying Prevention Intervention

Huddleston, Lillie 20 December 2012 (has links)
Treatment acceptability and treatment integrity are essential constructs to consider when designing, implementing, and evaluating school-based interventions. Existing literature has described treatment acceptability and treatment integrity as separate constructs rather than investigating their interrelationships. Also, models of treatment acceptability and treatment integrity have not systematically included the perspectives of multiple stakeholders, have not addressed multiple time points in the intervention process, and have not emphasized multiple methods of data collection. This paper reviewed extant literature related to current definitions and models of treatment acceptability and treatment integrity and presented a comprehensive integrated model of these constructs that addressed the aforementioned gaps in the intervention literature. A mixed methods study exploring student, facilitator, and observer perceptions of treatment acceptability and treatment integrity of an eight-week bullying prevention intervention was conducted. The study investigated the role of cultural modifications (i.e., context-based procedural or curriculum changes employed to enhance the treatment acceptability or integrity of the intervention). Qualitative data were analyzed with an inductive-deductive approach (Nastasi et al., 2004). Deductive coding was used to illustrate components of treatment acceptability, treatment integrity, and cultural modifications salient to this research and an inductive approach was used to identify emerging themes. Consensus coding was conducted with greater than 90% interrater agreement. Quantitative data were analyzed using descriptive statistics. Qualitative and quantitative analyses revealed positive findings with respect to treatment acceptability and treatment integrity. Facilitator competence, behavior management, student engagement, and time management emerged as qualitative themes related to treatment integrity. Qualitative data suggested a positive relationship between student and facilitator perceptions of treatment acceptability. Qualitative findings revealed modifications to the curriculum content and delivery based on cultural factors (e.g., gender and age) to enhance treatment acceptability. Implications for school-based bullying research and applied practice were described. The results suggested that the use of mixed methods enhanced the comprehensiveness, depth, and quality of data regarding stakeholder perceptions of treatment integrity and treatment acceptability.
147

Personlig integritet på Internet : En studie om attityder / Privacy on the Internet : A study of attitudes

Lindholm, Sara, Nandorf, Moa January 2010 (has links)
The internet has fundamentally changed the way people communicate. With all the information that we are sharing over the internet, and the ways which companies want to use our information, the importance of keeping our private information secure has increased. This thesis aims to discover what attitudes internet users have against privacy on the internet, and what – if anything – they are doing to protect their personal privacy. We distributed an online survey to internet users in the Stockholm area, and conducted three interviews with persons in our target population. The results of these studies show that people in general are very aware of privacy concerns on the internet, but that their attitudes toward how important personal privacy on the internet is, differ somewhat. / Internet har fundamentalt förändrat sättet som vi människor kommunicerar. Med all den information som vi delar med oss av över internet, och de olika sätten som företag vill använda vår information, så har vikten av att hålla viss information skyddad/privat/säker ökat. Denna uppsats ämnar att undersöka vilka attityder internetanvändare har till personlig integritet på internet, och vad – om något – de gör för att skydda sin personliga integritet. Vi delade ut en webbaserad enkät till internetanvändare i Stockholms län, och genomförde tre intervjuer med personer i vår målgrupp. Resultaten av dessa studier visar att människor generellt är väldigt medvetna om vikten att vara privat på internet, men att deras attityder mot hur viktigt personlig integritet på internet är, varierar.
148

Integritet och värdighet - patientens rättighet? : en litteraturstudie ur ett patientperspektiv

Karlsson, Anders, Korpas, Laszlo January 2011 (has links)
Sammanfattning Syftet med denna litteraturstudie var att belysa patienters syn på sin omvårdnad avseende integritet och värdighet vid sjukhusvistelse. Designen var en deskriptiv litteraturstudie och artiklar hämtades från databaserna Academic Search Elite, Cinahl och Medline via PubMed. Resultatet i denna studie visar att omgivning och arkitektoniska miljöer är framtonande orsaker till patienters negativa upplevelser i vården. Kommunikativa svårigheter och utebliven information om medicinska åtgärder och undersökningar, tillsammans med personalens bemötande och beteende, gör att patienters integritet och värdighet åsidosätts. Vårdtagarna vill känna delaktighet i sin vård och få information om sin situation vilket stärker känslan av att de behandlas med respekt från vårdpersonalens sida. Etiska kränkningar av patienters integritet och värdighet, under sjukhusvistelse, är i stort beroende av vårdpersonalens agerande vid vårdsituationer där patienter blottas eller utsätts för undersökningar utan tillräckligt skydd runt patienten. Slutsatsen för studien visar att mer informerande utbildning om integritet och värdighet behövs i vården tillsammans med ytterligare explorativ forskning i ämnet. / Abstract The aim of this study was to illuminate patients' views on their care for privacy and dignity due to their stay at a hospital. The design was a descriptive literature review and the articles were retrieved from the databases Academic Search Elite, Cinahl and Medline via PubMed. The result of this study shows that environment and architectural surroundings causes negative experiences for patients' in care. Communication difficulties and lack of information about medical procedures and examinations, along with staff's attitude and behavior, makes the patients' privacy and dignity disregarded. Health care consumers want to feel involved in their care and get information about their situation, which strengthens the feeling that they are treated with respect from medical personnel. Ethical violations of patient privacy and dignity during the hospital stay, is largely dependent on health professionals' conduct in the care setting where patients are exposed or subjected to investigations without adequate environmental protection around the patient. The conclusion of the study shows that more informative education is needed in health care concerning privacy and dignity together with further exploratory research on the subject.
149

Geomechanical analysis of caprock integrity

Soltanzadeh, Hamidreza 10 September 2009 (has links)
To safely store carbon dioxide in enhanced oil recovery/ CO2 sequestration projects it is important to ensure the integrity of the caprock during and after production and injection. A change in fluid pressure and temperature within a porous reservoir will generally induce stress changes within the reservoir and the rocks that surround it. Amongst the potential hazards resulting from these induced stress changes is the reactivation of existing faults or fractures and inducing new fractures, which may breach the hydraulic integrity of the caprock that bounds the reservoir.<p> The theories of inclusions and inhomogeneities have been used in this research to derive semi-analytical and closed-form solutions for induced stress change during pore pressure change within a reservoir and in the surrounding rock, under plane strain and axisymmetric conditions. Methods have been developed to assess fault reactivation and induced fracturing during injection or production within a reservoir. The failure stress change concept for a Coulomb failure criterion has been used to study the likelihood of fault reactivation and induced fracturing within the reservoir. Formulations have been adopted to calculate the critical pressure change for fault reactivation and induced fracturing within the reservoir and in the surrounding rock during injection and production. Sensitivity analysis has been performed to study the effects of different parameters such as initial in-situ stress, reservoir geometry, reservoir depth, reservoir tilt or dip , material property contrast between the reservoir and surrounding rock, fault geometry, fault strength, and intact rock strength. General patterns of induced stress change, in-situ stress evolution, fault reactivation, and induced fracturing have been identified.<p> The developed methodologies have been applied to six different case studies: fault reactivation analysis in the entire field for a synthetic case study; induced fracturing analysis in the entire field in a synthetic case study; fault reactivation and induced stress change analysis within the Ekofisk oil reservoir in North Sea; fault reactivation analysis in the Lacq gas reservoir in France; the Weyburn-Midale EOR/CO2 Storage project in southeast Saskatchewan; and acid gas injection in Zama oil field, Alberta. The results of these case studies show good consistency with field observation, and physical and numerical models.<p> The generality, simplicity, and straightforwardness of the developed methodologies, along with their flexibility to model different plausible scenarios and their ease of implementation for systematic sensitivity analyses makes them suitable for decision-making and uncertainty management, specifically in early stages of reservoir development or site assessment for geological sequestration of carbon dioxide.
150

Facebooka på arbetstid? : Upplevelsen av Facebook i privatlivet och arbetslivet

Jansson, Sofie, Manninen, Johanna January 2010 (has links)
Facebook har blivit ett av de mest populära redskapen för socialt nätverkande och kommunikation. År 2010 hade Facebook över 500 miljoner anhängare. Syftet med studien var att undersöka användandet av Facebook i privatlivet men även i relation till arbetslivet. En kvalitativ studie genomfördes via tillgänglighetsurval, det var naturligt i denna studie att finna respondenterna via Facebook. Intervjuerna var halvstrukturerade. Intervjuguiden var uppdelad utifrån olika ämnesområden: användandet av Facebook, Integritet, Sociala faktorer och Arbetsplatsen. Medverkande var 13 personer, varav fyra män som använde Facebook i arbetslivet. Resultatet visade att Facebook var ett populärt kommunikativt verktyg för att hålla kontakten med vänner, familj och kollegor och ett sätt att ta pauser i arbetet. Resultatet påvisade även oro kring hur respondenterna upplevde att de uppfattades av kollegor och chefer. Studien bidrar till ökad kunskap om hur Facebook påverkar anställda. Studien var ett bekvämlig-hetsurval.

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