• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 868
  • 325
  • 254
  • 60
  • 37
  • 20
  • 15
  • 11
  • 11
  • 11
  • 11
  • 11
  • 11
  • 10
  • 8
  • Tagged with
  • 1841
  • 1841
  • 477
  • 442
  • 323
  • 270
  • 264
  • 264
  • 222
  • 222
  • 212
  • 211
  • 205
  • 161
  • 149
  • 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.
451

The effects of using a cation exchange water softener on blood pressure

Kang, Ki Sung 29 August 1990 (has links)
Water in 70 percent of the cities in the United States is hard enough that softening is either required or recommended. It is estimated that approximately 30 percent of all homes in the United States use water softeners. Water softeners, the cation exchange types suited for residential use, exchange sodium for the calcium and magnesium in water. The increase in sodium levels in the softened water caused by cation exchange softening is a direct function of the hardness level of the untreated water. For people who use groundwater, which has a relatively high level of naturally occurring sodium, magnesium and calcium, the additional sodium from cation exchange water softeners may create health hazards for the general population and could adversely affect those who are sensitive to salt or on low sodium diets. To prevent potential health hazards for the general population, no consumption of softened water by cation exchange water softeners should be recommended. If soft water is needed for some practical reasons, a "Separate Water Line System" should be recommended for homeowners. / Graduation date: 1991
452

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.
453

A Study of the Impact of Decentralization on Access to Service Delivery

Saavedra, Pablo A. 08 January 2010 (has links)
This research builds further on the existing conceptual framework of the relationship between decentralization and service delivery and provides a cross-country empirical examination of the core dimensions of decentralization reform on access to two key services: health care and improved drinking water sources. The regression results provide evidence supporting positive and significant effects of fiscal, administrative, and political decentralization, individually, on the variables used to measure access to health care, and improved water provision; although the size and robustness of such effects varies for each dimension of decentralization in relation to each service examined. The results obtained in this study suggest that there is an additional (or "extra") positive effect coming from the interaction of two decentralization dimensions on access to health care and water services (that is, a mutually-reinforcing effect additional to the individual effect of each dimension of decentralization). The results obtained also support the expectation that developing countries could benefit significantly more from decentralization reforms compared to developed countries. These findings underscore the importance of considering all dimensions of the decentralization process when investigating the effects of this reform on any economic, institutional, or social variable. The policy implications are highly relevant, particularly for developing countries: decentralization implemented only through one dimension may render fewer positive fruits in terms of access to services than a multi-dimensional approach. Moreover, learning more about the most beneficial mutually-reinforcing effects across dimensions of decentralization may also help strategically in how the overall decentralization reform is designed.
454

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.
455

Women’s Role and Participation in Water Supply Management : The Case Study of the Republic of Ghana

Svahn, Karolin January 2012 (has links)
Women are increasingly being recognised internationally as essential actors in successful water supply management. Despite this, women are nevertheless still being excluded from water management activities which have proved to frequently result in water project failure. This has great consequences for water supply and water distribution capacity and efficiency. Women‟s exclusion often stems from traditional and deeply rooted gender differences where women, compared to men, are not given the same rights and opportunities. Therefore, in particular focuses in this study are cultural barriers and socio-economic obstacles and challenges that may hinder female participation. Although Ghana is considered to have rich water resources, the production, distribution and use of water is not efficient, sufficient, or sustainable. This impedes the country‟s socio-economic development. Most affected are women and children as they are often directly linked to the water source through their role as water collectors. In relation to this, the study investigates the importance of women‟s participation in water management within the Republic of Ghana. Furthermore, the study examines the efficiency and adequacy of measures and actions implemented to improve female participation in water supply management.  For data collection, a case study approach was adopted including an in-depth literature review, interviews with essential actors in Ghana and document analysis of Ghana‟s National Water Policy and National Gender and Children Policy. Interviews and documents were analysed with a content analysis and a comparative analysis approach.  The study found that women in Ghana, despite acknowledging their important role in Ghanaian water „society‟, experience great limitations in their participation in water management. Traditional norms and practices constitute a major obstacle together with a strongly male-dominated society that often prevents women from participating in the public sphere. The study indicates that there is a need to reform the legal system and the procedures of enforcement to encourage female participation in the water management. Furthermore, the Government of Ghana ought to improve financial, human, and material support within its agencies and associates to facilitate and enable female involvement. Moreover, there is a great need to improve women‟s rights to, and attendance in, education. Additionally, raising the awareness of gender and women‟s issues in general is crucial in order to initiate changes of traditional norms and practices and consequently improve their participation in the water management. By reforming Ghanaian women‟s situation, their role and status will be strengthened, not only within water management, but as well in the wider society.
456

Impacts of Natural Salt Pollution on Water Supply Capabilities of River/Reservoir Systems

Lee, Chi Hun 2010 May 1900 (has links)
Salinity is a major determinant of where and how water resources are used worldwide. Natural salt pollution severely constrains the beneficial use of large amounts of water in Texas and neighboring states. High salinity loads in several major river/reservoir systems, including the Brazos River, originate largely from salt seeps and springs in isolated areas of the upper river basins located in the Permian Basin geologic region. Research objectives were (1) to improve salinity simulation capabilities of the Water Rights Analysis Package (WRAP) modeling system, and (2) to develop a better understanding of the occurrence, transport, and impacts of salinity in the Brazos River and Lakes Possum Kingdom, Granbury, and Whitney. Water volume budgets and total dissolved solids load budgets were developed for five river reaches covering 405 miles of the upper Brazos River. Methodologies were developed for creating and applying WRAP salinity input datasets. The WRAP modeling system was expanded and applied to the entire Brazos River Basin to investigate alternative modeling premises and impacts of salinity and salinity control measures on water supply capabilities. Water and salinity budget analyses of the Brazos River system based primarily on measured stream flow, reservoir storage, and total dissolved solids data compiled by the U.S. Geological Survey were performed to explore the characteristics of flow and storage volumes and salinity loads and concentrations in the river/reservoir system. WRAP salinity input datasets were developed based on results from the salinity budget study. One dataset was designed and applied specifically for testing salinity routing methods and calibrating salinity routing parameters. A second complete basin salinity dataset was developed and applied to simulate the Brazos River Basin for alternative management strategies. The results of the simulations demonstrate, for example, that previously proposed salt control impoundments can significantly reduce salinity loads and concentrations in the three reservoirs and at all locations on the Brazos River from the impoundments downstream to the Gulf of Mexico. The WRAP salinity simulation features are designed to provide flexibility in combining water quantity simulation datasets from the Texas Water Availability Modeling System or other sources, which may be very complex, with available salinity data which varies in extent and format between different river basins. The modeling capabilities demonstrated by the Brazos River Basin study can be applied in other river basins as well.
457

The study about improving service quality of Kaohsiung city water.

Wang, Jin-Bao 06 August 2004 (has links)
none
458

An Investigation Of Water Supply In Roman Ankara

Kaytan, Emre 01 November 2008 (has links) (PDF)
The existence of two baths, if not more, in Roman Ankara reveals that a considerable amount of water was needed at least for the working of these baths. However, how and from where this water was supplied is not so clear because of the lack of both archaeological and historical evidence. In this regard, by bringing together all the archaeological data so far discovered and the available published information regarding the water supply scheme in order to see all this data collectively in a single picture, this thesis tries to investigate how and from where the water was supplied to Roman Ankara. In addition, this thesis reviews the available water potential of Ankara considering geography and hydrology of the site and also contains an analysis of how water was supplied in the more recent history of the city which is believed to contain invaluable information regarding the ancient water supply scheme of the city especially when the archaeological data is very scarce.
459

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.
460

Adsorption Characteristics of Fulvic Acid Derivated from Raw Water onto Carbon Nanotubes

Huang, Wei-Hsiang 23 July 2009 (has links)
Organic acids are usually the reactants which proceed in chlorination reaction into products of disinfection by-products in water treatment plant. The purpose of this study is by using tests of kinetics and equilibrium adsorptions to investigate adsorption characteristics and kinetic model evaluations of selected organic acid in solution. We use commercial carbon nano-tube for the adsorbents. The major factors in adsorption tests include the concentration of fulvic acid (a typical organic acid in raw water), pH, ionic strength and temperature. Experiment results exhibited kinetic adsorption reached equilibrium about 120 minutes, the adsorption capacity increased with concentrations increasing of fulvic acid and decreased with ionic strengths. The best selection in kinetic models evaluation, fitting models such as Modified Freundlich equation, Pseudo-1st-order equation and Pesudo-2nd-oder equation is Modified Freundlch equation model. In addition, intraparticle diffusion equation model was fitted well and showed adsorption process was controlled with pore diffusion. The maximum adsorption capacity varied from 26.094 to 20.772 mg/g when temperature ranging from 4 to 45¢J. Isotherm adsorption results were fitted on Langmuir and Freundich models. The £GG¢X values ranged from -0.930 to -1.014 kcal/mol, £GH¢X:-1.561 kcal/mol and £GS¢X:-2.02 cal/mol. Thermodynamic parameters indicated that the adsorption is spontaneously and an exothermic reaction. Adsorption of fulvic acid by carbon nano-tube has a good performance when operation conditions of higher fulvic acid concentration, lower ionic strength, lower pH and lower temperature.

Page generated in 0.205 seconds