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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.
241

Mechanical properties of low density fibre-reinforced cellular concrete and its energy absorption potential against air blast

Amirrasouli, Benyamin January 2015 (has links)
The scope of this study is to establish extensive material tests to determine the mechanical properties of cellular concrete and evaluate its potential as energy absorption material against air blast load. This study includes a literature review of existing studies on cellular concrete, proportioning, and its mechanical properties, together with studies on the properties and application of other foams such as aluminium and polymer foams. It is concluded that, unlike other foam materials, there is a lack of systematic studies on the mechanical properties of cellular concrete especially for densities less than 1000 kg/m3. The survey also reviewed the existence of materials being used as a sacrificial layer against air blast load, together with the analytical models proposed to determine the parameters required to design a cladding system. As a result it was found that cellular concrete can maintain most of the properties of the cladding materials and can be applied as a new sacrificial layer against the blast load. Extensive material tests are carried out to characterise the effect of ingredients and density on material properties of cellular concrete. Based on the experimental results, an empirical model is proposed which determines the plateau and densification regime of nominal stress-strain curve of the cellular concrete with different densities. The penetration resistance of cellular concrete with different densities under truncated, conical, flat and hemi-spherical solid indenters are studied experimental. By determining the deformation mechanism of cellular concrete under indentation with application of an X-Ray tomography image system, an analytical model is proposed to determine the resistance of cellular concrete under penetration of flat indenter. Experimental closed range blast tests are performed with 1kg and 3kg C4 explosive to determine the mitigation potential of cellular concrete against air blast load. Numerical modelling of the experimental blast test is carried out using Ansys LS-DYNA to evaluate the feasibility of the numerical modelling techniques to predict the response of cellular concrete against air blast load.
242

Framework for assessment of economic feasibility of voltage sag mitigation solutions

Chan, Jhan Yhee January 2010 (has links)
Current practices of power quality mitigation in the industry are characterized by sub-optimal investment decisions where over compensation is often the norm such causing huge wastage in financial resources. Providing power quality management services to industrial customers in the form of power quality contracts could yield substantial return for the network operator. With better understanding of network parameters, and the option of installing network level mitigation devices, network operators could employ wider range of cost effective mitigation solutions. Tapping into the market however, entails bearing the risks for the customers which network operators are not always willing or encouraged to do. With potentially millions at stake, extensive risk assessments are crucial for any proposed power quality management scheme. This thesis investigates the voltage sag aspect of the problem as part of a larger power quality management scheme. The aim is to develop general framework for technical and financial assessments of voltage sags prior to the introduction of power quality management service. The thesis focuses on five major aspects of voltage sag assessment: identification of customer requirement, financial loss assessment, network sag performance estimation, sag mitigation, and financial appraisal of mitigating solutions. The first part of the thesis gives a comprehensive overview of current power quality problems faced by industrial customers and provides ranges of typical financial losses incurred by different types of industries around the world. It then proposes robust methodology for assessment of typical financial loss, i.e., customized customer damage function (CCDF), for a given industry based on available survey data and taking into account characteristics of the assessed customer plant. For failure and financial risk assessments, the thesis introduces new customer models employing probabilistic methods to quantify risks induced by voltage sags and proposes generic models that incorporate full flexibility in failure risk assessment, taking into account the effect of unbalanced sags on equipment behavior. It further quantifies the error introduced by sag performance estimation using limited monitoring data with a case study on actual sag profile. It demonstrates how different estimation methods and different durations of monitoring period affect accuracy of estimation of voltage sag profile and associated risk of industrial process failure. Following this, the thesis presents new models for plant and network level sag mitigation devices. They include power injecting mitigation devices, devices that reduce number of faults in the network and devices that reduce the severity of faults. Developed models are then used to investigate the cost-effectiveness of sag mitigation at different levels. Finally, the thesis presents Genetic Algorithm based methodology for deciding on optimal investment scheme in voltage sag mitigation in the network. The sensitivity of the solution to various influential parameters, including plant type and size, sensitive equipment type, process characteristics, financial loss resulting from process interruption, cost and effectiveness of mitigating solution and network fault rates is also established.
243

Defining the constructs of a safety climate measurement tool to determine readiness for a behavioral approach to safety management

Pather, Desigan January 2014 (has links)
Safety climate provides an indication of the perceptions of employees with regard to safety management in an organisation. Although there have been many studies on safety climate, a common platform to measure safety climate has not yet been agreed upon. This makes it difficult to compare climate performance across industries and organisations. This study endeavors to identify the common thread that flows through all safety climate studies through extensive literature review and develop safety climate measurement tool in the form a 65 question survey. The survey was validated using confirmatory factor analysis and expert review. The study further looks at the elements of safety climate that affect the behavioral safety management and determines how an organisation performs on those identified elements through descriptive statistic models.100 employees of a large petrochemical organisation based in South Africa participated in the survey. The results required that several of the questions in the survey be reevaluated and therefore the survey will need to be re tested. The results also demonstrated that the sample organisation had considered and implemented the elements of safety climate that are required for a behavioral safety program. / Dissertation (MBA)--University of Pretoria, 2014. / lmgibs2015 / Gordon Institute of Business Science (GIBS) / Unrestricted
244

Security Assessment and *nix Package Vulnerabilities

Sandgren, Per January 2018 (has links)
Background. Vulnerabilities in software provides attackers with the means to fulfill unlawful behavior. Since software has so much power, gaining control over vulnerabilities can mean that an attacker gains unauthorized powers. Since vulnerabilities are the keys that let attackers attack, vulnerabilities must be discovered and mitigated. Scanning vulnerable machines is not enough, and scanning data results must be parsed to prioritize vulnerability mitigation and conduct security assessment. Objectives. Creating a parser is the first objective, a tool that takes in input, filters it and gives output specified by the parser. The second objective is to have the parser connect found packages to known vulnerabilities. And the last objective is to have the parser give the output more information, sort them by severity and give information on what areas they are vulnerable. Methods. The interviews are conducted on experienced employees at Truesec AB. A parser is implemented with guidance from the supervisor at Truesec. The parser is experimented with to check practicality of parser. Results. The parser can find vulnerabilities from the Centos tests and does not find any from the Debian tests. From the interviews, we see that more information strengthens a security assessment. Expanding the scanning results will provide more information to the person(s) conducting security assessment. Conclusions. The amount of information gathered in security assessment needs to be expanded to make the assessment more reliable. Packages found can be connected with vulnerabilities by implementing a vulnerability database to match packages. The parser developed does not help in security assessment since the output is not reliable enough, this is caused by the phenomenon backporting.
245

Supporting energy transitions and miscanthus program development at the University of Iowa

Lain, Kayley Christina 01 May 2017 (has links)
Miscanthus is a highly productive, low-input biofuel crop that supports agricultural diversification with improved performance for climate commitment, energy security, and water quality over first generation biofuels. Despite its high performance, no local or regional markets for the feedstock have formed in North America, and current climate-based productivity assessment methods lack the information farmers and decision-makers need to establish commercial scale bioenergy markets, programs, and thermal co-firing plans. This study develops a Miscanthus Suitability Rating and a transferable field-scale siting method, applied at 10 m resolution across the State of Iowa to assess miscanthus production potential and identify individual farms that are highly suitable for large-scale miscanthus cultivation while maintaining a majority of existing row cropping acreage. Results show that highly suitable fields within 50 miles (84 km) of each of Iowa’s coal-fired electrical generating units (EGUs) can displace up to 43% of current coal consumption. Every EGU in Iowa has land resource to produce local miscanthus to co-fire with other solid fuels at industry-leading levels without significantly impacting local row crop production. Seven of the state’s smaller facilities could even operate exclusively on local miscanthus with advancements in densification technology. The energy evaluation tool developed in this work estimates the energy return on investment (EROI) of Iowa miscanthus for existing thermal generation facilities between 37 and 59, depending on transportation requirements and chemical field applications. This transition would diversify local agribusiness and energy feedstocks, reduce greenhouse gas emissions and provide a sustainable, dispatchable, in-state fuel source to complement wind and solar energy.
246

Mitigation of magnetic interference and compensation of bias drift in inertial sensors

Frick, Eric Christopher 01 May 2015 (has links)
Magnetic interference in the motion capture environment is caused primarily by ferromagnetic objects and current-carrying devices disturbing the ambient, geomagnetic field. Inertial sensors gather magnetic data to determine and stabilize their global heading estimates, and such magnetic field disturbances alter heading estimates. This decreases orientation accuracy and therefore decreases motion capture accuracy. The often used Kalman Filter approach deals with magnetic interference by ignoring the magnetic data during periods interference is encountered, but this method is only effective when the disturbances are ephemeral, and cannot not retroactively repair data from disturbed time periods. The objective of this research is to develop a method of magnetic interference mitigation for environments where magnetic interference is the norm rather than the exception. To the knowledge of this author, the ability to use inertial and magnetic sensors to capture accurate, global, and drift-free orientation data in magnetically disturbed areas has yet to be developed. Furthermore there are no methods known to this author that are able to use data from undisturbed time periods to retroactively repair data from disturbed time periods. The investigation begins by exploring the use of magnetic shielding, with the reasoning that application of shielding so as to impede disturbed fields from affecting the inertial sensors would increase orientation accuracy. It was concluded that while shielding can mitigate the effect of magnetic interference, its application requires a tedious trial and error testing that was not guaranteed to improve results. Furthermore, shielding works by redirecting magnetic field lines, increasing field complexity, and thus has a high potential to exacerbate magnetic interference. Shielding was determined to be an impractical approach, and development of a magnetic inference mitigation algorithm began. The algorithm was constructed such that magnetic data would be filtered before inclusion in the orientation estimate, with the result that exposure in an undisturbed environment would improve estimation, but exposure to a disturbed environment would have no effect. The algorithm was designed for post-processing, rather than real-time use as Kalman Filters are, which enabled magnetic data gathered before and after a time point could affect estimation. The algorithm was evaluated by comparing it with the Kalman Filter approach of the company XSENS, using the gold standard of optical motion capture as the reference point. Under the tested conditions of stationary periods and smooth planar motion, the developed algorithm was resistant to magnetic interference for the duration of testing, while the Kalman Filter began to degrade after approximately 15 seconds. In a 190 second test, of which 180 were spent in a disturbed environment, the developed algorithm resulted in 0.4 degrees of absolute error, compared to the of the Kalman Filter’s 78.8 degrees. The developed algorithm shows the potential for inertial systems to be used effectively in situations of consistent magnetic interference. As the benefits of inertial motion capture make it a more attractive option than optical motion capture, immunity to magnetic interference significantly expands the usable range of motion capture environments. Such expansion would be beneficial for motion capture studies as a whole, allowing for the cheaper, more practical inertial approach to motion capture to supplant the more expensive and time consuming optimal option.
247

The Effect of Risk Evaluation and Mitigation Strategies (REMS) On Healthcare Provider's Awareness of Drug Risks

January 2017 (has links)
acase@tulane.edu / 1 / Shelly L Harris
248

UNDERSTANDING CLIMATE RESILIENCE TO ENVIRONMENTAL HAZARDS: HOW A BROWARD COUNTY COMMUNITY ASSESSMENT HELPS TO COMPLETE THE PICTURE

Unknown Date (has links)
Climate patterns over the past century served to amplify the frequency and intensity of environmental hazards, including flooding, wind and heat. While indicators like SoVi and BRIC begin to characterize how people and places fair against hazards, they can be limited in scope. Through the administration of household surveys, I investigate the usefulness of such indicators by examining the roles communication, infrastructure, institutional efforts, financial independence, knowledge, mobility and social capital play in producing resilience within the Estates of Fort Lauderdale Community in Dania Beach, FL. While results confirm BRIC’s Medium-High Resilience community classification, they push beyond Census data to pinpoint underlying resilience processes. Responses indicate community classification, they push beyond Census data to pinpoint underlying resilience processes. Responses indicate that place attachment and community connectedness encourage weather-related information sharing, limited experiences and skills impede weather preparedness and response actions, and weather preparedness and response experiences are associated with less evacuation than expected. Findings prove to be richer and more policy and program actionable. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection
249

Understanding and teaching climate change in the Secondary Education Geography Curriculum in Swaziland

Dlamini, Mandlenkhosi Nhlanhla January 2016 (has links)
Climate change education is globally recognised as a key approach through which to enhance the knowledge and understanding of climate change among learners and teachers. This study thus sought to investigate the understanding and teaching of climate change in the Secondary Education Geography Curriculum in Swaziland. The major goal of this study was to establish the understanding and teaching of climate change in the secondary education Geography curriculum of the country. To investigate the understanding and teaching of climate, the study employed an exploratory design comprising methods like questionnaire, focus group interviews as well as document analysis in the form of secondary records. The data was collected from 16 principals, 32 Geography teachers from 16 high schools; four from each region of Swaziland, one Senior Environmental Education Officer, one senior inspector of Geography and one senior Geography curriculum designer. Numerous gaps and misconceptions were found to exist in learners and teachers understanding of climate change education. The findings reflected that the teachers were not comfortable with the integration of climate change education into all the secondary education Geography curriculum lessons. However, they claimed to be unknowingly practising its integration to a limited extent. Although the teachers generally supported the integration of climate change education into the geography curriculum, they cited challenges like lack of proper training on climate change education, a shortage of teaching resources on CCE and the already overcrowded geography curriculum which then made it impossible for CCE integration. The study recommends that the Ministry of Education and Training need to train teachers on CCE both at in-service and pre-service level and providing the resources required for CCE, for instance, the internet and good libraries for research, since CCE requires perpetual learning. / Thesis (PhD)--University of Pretoria, 2016. / Humanities Education / PhD / Unrestricted
250

Právní nástroje ochrany klimatu v rámci "effort sharingu" / Effort sharing as a legal measure of climate protection

Srb, Jáchym January 2020 (has links)
Master thesis "Effort sharing as a legal measure of climate protection" strives to give a comprehensive account of the key characteristics of the effort sharing system, which is one of the two principal EU mitigation tools of the EU. In order to provide a better insight, the thesis first discusses the topic in context of economic theory and international law on climate. The thesis itself is divided into four chapters. First chapter defines the object of climate regulation i.e. greenhouse gases their production and the legal framework of their measuring and accounting.Second chapter focuses on the economic background of climate regulation and it compares different theoretical approaches with existing regulation in force on international and European level. Third chapter gives basic account of the international framework of climate law and specifically on the international mitigation obligations of the EU, which are relevant for the EU law. Fourth and final chapter describes the main aspects of the effort sharing system in contrast to the EU ETS. It draws mainly from the Decision no. 406/2009/ES, which is currently in force and the Regulation no. 2018/842, which will shape the effort sharing system for the 2021 - 2030 period. In four sub- chapters it focuses on the definition of regulated emission...

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