• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 20
  • 13
  • 9
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 50
  • 50
  • 50
  • 16
  • 13
  • 12
  • 11
  • 8
  • 7
  • 7
  • 7
  • 6
  • 6
  • 6
  • 6
  • 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.
1

A Parametric Simulation Model for Evaluating Cost Effectiveness of Remote Monitoring for Risk Reduction in Rural Water Supply Systems and Application to the Tazewell County, Virginia System

Wetzel, George L. 30 October 2003 (has links)
A simulation model analyzes cost effectiveness of remote facility monitoring for risk reduction in rural water supply systems by performing a break-even analysis that compares operating costs with manual and remote monitoring. Water system operating cost includes the value of water loss (i.e., realized risk) resulting from operating excursions which are inversely related to mechanical reliability. Reliability is controlled by facility monitoring that identifies excursions enabling operators to implement mitigating measures. Cost effectiveness refers to the cost relationship among operating alternatives that reveals changed economic conditions at different operating rates inherent in the inverse relationship between fixed and variable costs. Break-even analysis describes cost effectiveness by identifying the operating rate above which the more capital intensive alternative will result in lower operating cost. Evidence indicates that increased monitoring frequency associated with remote monitoring can reduce water system operating cost by improving reliability, but whether remote monitoring is cost effective depends upon system-specific factors. The lack of a documented tool for evaluating this type of cost effectiveness led to the project objective of developing a model that performs break-even analysis by simulating water system operating costs as functions of system size (delivery rate). When the spreadsheet-based static deterministic parametric simulation model is run for the Tazewell County, Virginia water system based upon 1998 data, break even is predicted at approximately fifty-five percent of annual capacity (116,338,000 gallons) with operating cost of $1,043,400. Maximum annual operating cost reduction from a $317,600 investment provides payback in nine years. / Master of Science
2

Risk Assessment of a Water Supply System under Climate Variability: A Stochastic Approach

Yung, Beatrice Biau 22 January 2008 (has links)
In this study, a model is developed to assess risk to a municipal water supply system under the influence of population growth and climate change. To incorporate the uncertainly in water use, a model which combines time series Monte Carlo simulations and a deterministic artificial neural network (ANN) is developed to simulate the daily water demand under climate variability. The model is then expanded in two directions. One direction is to estimate the effects of demand management programs and system expansion on the reliability, resiliency, and vulnerability of the water supply system. Another direction is to capture the possible impacts of climate change on the risk of a water supply system. Twenty-six scenarios generated from different combinations of demand management programs, system expansions and Global Climate Model (GCM) scenarios were set to illustrate the risk indices: reliability, resiliency, and vulnerability. To illustrate the effects of a change of precipitation frequency and a higher population growth, twenty-five additional scenarios were evaluated.
3

Risk Assessment of a Water Supply System under Climate Variability: A Stochastic Approach

Yung, Beatrice Biau 22 January 2008 (has links)
In this study, a model is developed to assess risk to a municipal water supply system under the influence of population growth and climate change. To incorporate the uncertainly in water use, a model which combines time series Monte Carlo simulations and a deterministic artificial neural network (ANN) is developed to simulate the daily water demand under climate variability. The model is then expanded in two directions. One direction is to estimate the effects of demand management programs and system expansion on the reliability, resiliency, and vulnerability of the water supply system. Another direction is to capture the possible impacts of climate change on the risk of a water supply system. Twenty-six scenarios generated from different combinations of demand management programs, system expansions and Global Climate Model (GCM) scenarios were set to illustrate the risk indices: reliability, resiliency, and vulnerability. To illustrate the effects of a change of precipitation frequency and a higher population growth, twenty-five additional scenarios were evaluated.
4

Apply the concepts of evidence-based medicine to develop the risk management strategy in hospital-acquired legionnaires¡¦ disease

Chien, Shang-Tao 12 June 2008 (has links)
Hospital-acquired Legionnaires¡¦ Disease (LD) is a bacterial pneumonia caused by the genus of Legionella. It is an opportunistic pathogen with the characteristic of widespread distribution in the environment. Its source of infection associates with potable water systems. Proactively culturing hospital water supply for Legionella as a strategy for prevention of nosocomial LD has been widely adopted in other countries. Nosocomial LDs has been hardly reported in Taiwan. In addition, environmental cultures of Legionella in potable water systems in hospitals have not been systematically implemented. Thus, the purpose of the research is to confirm if LD presents in the hospital in Taiwan, and developing risk management strategy in hospital-acquired LD. To practice one-year prospective surveillance program for LD, we choose a military hospital in Southern Taiwan, collecting the specimens from the nosocomial and community-acquired pneumonia patients for legionella investigations. In the meanwhile, we collect water samples for hospital epidemiological investigation every 3 months. Isolated Legionella pneumophila is serotyped and analyzed by pulsed-field gel electrophoresis. From Nov 1, 2006 to Oct 30, 2007, within 54 cases of nosocomial and 300 cases of community-acquired pneumonia, only one case of nosocomial LD was found. Environmental investigations detected L. pneumophila in 17(20.7%) of the 84 water samples, of which 82.4% (14/17) belonged to serogroup 1. The result demonstrated the infection source of the only positive case of nosocominal pneumonia is the potable water supply system of another hospital. In conclusion: 1. The infection source of nosocomial LD is the potable water supply system of the hospital. 2. The positive rate of distal outlets for L. pneumophila is a reasonable and reliable indicator in risk management for nosocomial LD. 3. Uncovered cases of nosocomial LD will be found in prospective clinical surveillance for LD. Suggestions: 1. Routine water-quality monitoring should be added in environmental water culture for L. pneumophila in the institution, such as hospital, nursing home, hotel, restaurant, SPA, swimming pool, hot spring, school, army, etc. 2. We advise that government health department carries out national surveillance for hospital water environment in determining the risk of hospital-acquired LD. 3. Education and training program need to be provided for medical staffs in the diagnostic skills of nosocomial LD to avoid misdiagnosing and delaying the treatment.
5

Pesquisa de indicadores para gestão de sistemas abastecimentos de agua

Silva, Neusa Aparecida Sales 14 March 2004 (has links)
Orientador: Edevar Luvizotto Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-11T18:08:54Z (GMT). No. of bitstreams: 1 Silva_NeusaAparecidaSales_M.pdf: 3550514 bytes, checksum: 2963e1b4e84aea2fc6b498b7ef92c3dc (MD5) Previous issue date: 2003 / Resumo: A gestão de uma empresa de abastecimento de água fundamenta-se em um conjunto de dados gerais, sobre os quais se geram informações (dados tratados) através das quais são tomadas decisões de ações efetivas. As informações se traduzem normalmente em indicativos puros, tais como número de consumidores, extensão da rede, volume produzido, volume consumido, etc. As devidas relações destes indicativos ¿puros¿ podem fornecer valiosas informações de diagnostico do sistema. Tais relações são chamadas de ¿guias¿ ou indicadores de gestão. O presente trabalho coletou da literatura (de organizações de reconhecida credibilidade) um conjunto de 254 indicadores de gestão para empresas de abastecimento. Estes indicadores foram submetidos à análise, por meio de questionário apropriado, pelos diversos setores de um grupo de empresas selecionadas. O resultado das análises, fornece indícios do baixo emprego e conhecimento de indicadores de gestão por parte das empresas de abastecimento (a menos dos exigidos por parte de órgãos de financiamento). Também a falta de uma cultura de manutenção de um banco de dados atualizados, a falta de um rigor no trato destas informações, põem em duvida os valores obtidos para os indicadores utilizados como contribuição deste trabalho. Aproveitando o resultado dos questionários o trabalho estabelece um conjunto de 61 indicadores que parece atender em conjunto a todos os entrevistados sendo portanto tomados como o elenco básico de indicadores de gestão / Abstract: The management of a water suply company is based on general data. One conceive information about this data, and with these information one can take decisions of effective actions. The information are translated in pure indicators, such as number of consumers, the net length, produced and cosumed volume, etc. The proper relations between these pure indicators may supply worth information for the diagnosis of the system. Such relations are called ¿Guides¿ or management indicators. This paper has collected from the literature from the organizations that have recognized credibility a set of 254 management indicators for water supply companies. These indicators were analised, by means of proper questionnaire, by several sections from some chosen companies. The result of this analisis, shows that the water supply companies has a low use and knowledge of these management indicators except those that are required by the finance companies. Also the lack of a culture of maintenance of updated data, the lack of a rigor in treat these information, make the values got to the indicators used as a contribuition for this paper doubtful. Using the questionnaires result this paper establish a set of 61 indicators that seems to serve all the interwied people and so they are used as the basic management indicadores / Mestrado / Recursos Hidricos / Mestre em Engenharia Civil
6

Harvesting Clean Water from Air

Li, Renyuan 11 1900 (has links)
Water scarcity has caused severe impact on the entire ecosphere while the climate change is resulting in high frequency of extreme weather conditions, especially extended period of drought. Due to the even increasing world’s population and the continued societal modernization, water scarcity is now one of the leading global challenges towards the development of human society. On the other hand, atmospheric water, accounting for 6 times the water in all rivers on Earth, is emerging as an alternative water resource. This dissertation thoroughly investigated the fully solar energy driven atmospheric water harvesting (AWH) process in a broad scientific and application context. The light-to-heat conversion process of solar photothermal materials was investigated first with a rationally designed droplet-laser system, which in combination with the calculation of heat of absorption of water vapor for various application scenarios, formed a theoretical basis of this dissertation research. As a result, a series of commonly used hydrated salts and their anhydrous counterparts were judiciously selected and successfully proven to be low-cost AWH materials to generate clean fresh water for arid regions. A hydrogel-deliquescent salt composite was further developed as AWH material with a significantly enhanced fresh water production capacity. A new design of nano-capsule encapsulated deliquescent salt was further put forward to enhance water vapor sorption/desorption kinetics, which enabled, for the first time, multiple sorption/desorption cycles within one day and thus multiplied water production capacity. The first-ever continuous AWH device, as opposed to batch-type one, was rationally designed, fabricated, and successfully tested in field conditions outdoors. At last, the dissertation pioneered a novel concept of atmospheric water sorption and desorption cycle for photovoltaic (PV) panel cooling. This dissertation shines significant light on sorption based atmospheric water harvesting and inspires more research efforts on this important research topic.
7

Application of Optimization Techniques to Water Supply System Planning

Lan, Fujun January 2014 (has links)
Water supply system planning is concerned about the design of water supply infrastructure for distributing water from sources to users. Population growth, economic development and diminishing freshwater supplies are posing growing challenges for water supply system planning in many urban areas. Besides the need to exploit alternative water sources to the conventional surface and groundwater supplies, such as reclaimed water, a systematic point of view has to be taken for the efficient management of all potential water resources, so that issues of water supply, storage, treatment and reuse are not considered separately, but rather in the context of their interactions. The focus of this dissertation is to develop mathematical models and optimization algorithms for water supply system planning, where the interaction of different system components is explicitly considered. A deterministic nonlinear programming model is proposed at first to decide pipe and pump sizes in a regional water supply system for satisfying given potable and non-potable user demands over a certain planning horizon. A branch-and-bound algorithm based on the reformulation-linearization technique is then developed for solving the model to global optimality. To handle uncertainty in the planning process, a stochastic programming (SP) model and a robust optimization (RO) model are successively proposed to deal with random water supply and demand and the risk of facility failure, respectively. Both models attempt to make the decision of building some additional treatment and recharge facilities for recycling wastewater on-the-site. While the objective of the SP model is to minimize the total system design and expected operation cost, the RO model tries to achieve a favorable trade-off between system cost and system robustness, where the system robustness is defined in terms of meeting given user demands against the worst-case failure mode. The Benders decomposition method is then applied for solving both models by exploiting their special structure.
8

Enhanching Security in the Future Cyber Physical Systems

Manandhar, Kebina 11 May 2015 (has links)
Cyber Physical System (CPS) is a system where cyber and physical components work in a complex co-ordination to provide better performance. By exploiting the communication infrastructure among the sensors, actuators, and control systems, attackers may compromise the security of a CPS. In this dissertation, security measures for different types of attacks/ faults in two CPSs, water supply system (WSS) and smart grid system, are presented. In this context, I also present my study on energy management in Smart Grid. The techniques for detecting attacks/faults in both WSS and Smart grid system adopt Kalman Filter (KF) and χ2 detector. The χ2 -detector can detect myriad of system fault- s/attacks such as Denial of Service (DoS) attack, short term and long term random attacks. However, the study shows that the χ2 -detector is unable to detect the intelligent False Data Injection attack (FDI). To overcome this limitation, I present a Euclidean detector for smart grid which can effectively detect such injection attacks. Along with detecting attack/faults I also present the isolation of the attacked/faulty nodes for smart grid. For isolation the Gen- eralized Observer Scheme (GOS) implementing Kalman Filter is used. As GOS is effective in isolating attacks/faults on a single sensor, it is unable to isolate simultaneous attacks/faults on multiple sensors. To address this issue, an Iterative Observer Scheme (IOS) is presented which is able to detect attack on multiple sensors. Since network is an integral part of the future CPSs, I also present a scheme for pre- serving privacy in the future Internet architecture, namely MobilityFirst architecture. The proposed scheme, called Anonymity in MobilityFirst (AMF), utilizes the three-tiered ap- proach to effectively exploit the inherent properties of MF Network such as Globally Unique Flat Identifier (GUID) and Global Name Resolution Service (GNRS) to provide anonymity to the users. While employing new proposed schemes in exchanging of keys between different tiers of routers to alleviate trust issues, the proposed scheme uses multiple routers in each tier to avoid collaboration amongst the routers in the three tiers to expose the end users.
9

Quantitative Approach to Select Energy Benchmarking Parameters for Drinking Water Utilities

Chanpiwat, Pattanun 04 June 2014 (has links)
Energy efficiency is currently a hot topic on all regional, national, and global stages. Accurate measurements on how energy is being used over a period of time can improve performance of the drinking water utility substantially and reduce energy consumption. Nevertheless, the drinking water industry does not have a specific benchmarking practice to evaluate its energy performance of the system. Therefore, there are no standards to compare energy use between water utilities that have a variety of system characteristics. The goal of this research is to develop quantitative approach to select energy benchmarking parameters of the water system, so the drinking water utilities can use those parameters to improve their energy efficiency. In addition to a typical benchmarking of drinking water utilities, the energy benchmarking can specifically compare energy efficiency of a utility with other utilities nationwide. The research developed a regression model based on the statistical representation of the energy use and descriptive characteristics of the drinking water utilities data throughout the U.S. Methodologies to eliminate singularity and multicollinearity from collinear survey dataset are discussed. The all possible regressions were chosen as parameters selection methodology to identify a subset of most significant parameters, i.e. system characteristics, that can mathematically correspond to energy use across different utilities. As a result, the energy benchmarking would be able to calculate the predicted total energy use of the system from given system characteristics. / Master of Science
10

Nouzové zásobování vodou v krizových situacích / Emergency water supply in crisis situations

DUŠKOVÁ, Radka January 2011 (has links)
The following diploma thesis deals with those problems related to the emergency water supply in crisis situations in the South Bohemian Region and with working procedures related to protection of residents during preparation and application of the emergency water supply. The objective of this diploma thesis is to determine those special characteristics of the emergency water supply in crisis situations and to compare the possibilities of the emergency water supply in crisis situations in selected regions. The theoretical part provides a basic survey of legislation related to the topic, as well as that of other methodical documents which are necessary for solving this type of crisis. Furthermore, the theoretical part unifies selected specialised terminology and characterizes the system of the regular (non-emergency) water supply, which represents the basic pillar for the emergency water supply. Last but not least, the theoretical part summarises those problems related to the emergency water supply and risk factors that can cause or significantly influence it. The practical part deals with those characteristics and their comparison of the selected regions in the South Bohemian Region, by using those specific indicators that are related to the water supply. The quantitative research was carried out by using the definition of what the special characteristics of the emergency drinking water supply are, in 17 administration districts of municipalities with extended competence in the South Bohemian Region. The data provided by the Czech Statistical Office were also used. Furthermore, a description statistics of the differences between the individual administrative districts of these municipalities with extended competence in the South Bohemian Region was carried out, as well as the quantification of those identified special characteristics of the emergency water supply. Finally, a statistical investigation of the identified special characteristics was carried out, as well as a test of a distribution-free hypothesis about the division of statistical data. Based upon the research that has been carried out, the final part of this thesis confirms two stipulated hypotheses about the dependence of the emergency water supply in crisis situations, based upon specific local conditions and about preparedness of the crisis management authorities for situations which would require an emergency water supply.

Page generated in 0.0849 seconds