• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 192
  • 137
  • 95
  • 29
  • 11
  • 10
  • 8
  • 8
  • 7
  • 7
  • 6
  • 4
  • 3
  • 2
  • 2
  • Tagged with
  • 591
  • 591
  • 130
  • 122
  • 100
  • 95
  • 82
  • 71
  • 70
  • 61
  • 59
  • 46
  • 45
  • 42
  • 41
  • 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.
31

Economic analysis of malnutrition and pressure ulcers in Queensland hospitals and residential aged care facilities

Banks, Merrilyn Dell January 2008 (has links)
Malnutrition is reported to be common in hospitals (10-60%), residential aged care facilities (up to 50% or more) and in free living individuals with severe or multiple disease (>10%) (Stratton et al., 2003). Published Australian studies indicate similar results (Beck et al., 2001, Ferguson et al., 1997, Lazarus and Hamlyn, 2005, Middleton et al., 2001, Visvanathan et al., 2003), but are generally limited in number, with none conducted across multiple centres or in residential aged care facilities. In Australia, there is a general lack of awareness and recognition of the problem of malnutrition, with currently no policy, standards or guidelines related to the identification, prevention and treatment of malnutrition. Malnutrition has been found to be associated with the development of pressure ulcers, but studies are limited. The consequences of the development of pressure ulcers include pain and discomfort for the patient, and considerable costs associated with treatment and increased length of stay. Pressure ulcers are considered largely preventable, and the demand for the establishment of appropriate policy, standards and guidelines regarding pressure ulcers has recently become important because the incidence and prevalence of pressure ulcers is increasingly being considered a parameter of quality of care. The aims of this study program were to firstly determine the prevalence of malnutrition and its association with pressure ulcers in Queensland Health hospitals and residential aged care facilities; and secondly to estimate the potential economic consequences of malnutrition by determining the costs arising from pressure ulcer attributable to malnutrition; and the economic outcomes of an intervention to address malnutrition in the prevention of pressure ulcers. The study program was conducted in two phases: an epidemiological study phase and an economic modelling study phase. In phase one, a multi centre, cross sectional audit of a convenience sample of subjects was carried out as part of a larger audit of pressure ulcers in Queensland public acute and residential aged care facilities in 2002 and again in 2003. Dietitians in 20 hospitals and six aged care facilities conducted single day nutritional status audits of 2208 acute and 839 aged care subjects using the Subjective Global Assessment, in either or both audits. Subjects excluded were obstetric, same day, paediatric and mental health patients. Weighted average proportions of nutritional status categories for acute and residential aged care facilities across the two audits were determined and compared. The effects of gender, age, facility location and medical specialty on malnutrition were determined via logistic regression. The effect of nutritional status on the presence of pressure ulcer was also determined via logistic regression. Logistic regression analyses were carried out using an analysis of correlated data approach with SUDAAN statistical package (Research Triangle Institute, USA) to account for the potential clustering effect of different facilities in the model. In phase two, an exploratory economic modelling framework was used to estimate the number of cases of pressure ulcer, total bed days lost to pressure ulcer and the economic cost of these lost bed days which could be attributed to malnutrition in Queensland public hospitals in 2002/2003. Data was obtained on the number of relevant separations, the incidence rate of pressure ulcer, the independent effect of pressure ulcers on length of stay, the cost of a bed day, and the attributable fraction of malnutrition in the development of pressure ulcers determined using the prevalence of malnutrition, the incidence rate of developing a pressure ulcer and the odds risk of developing a pressure ulcer when malnourished (as determined previously). A probabilistic sensitivity analysis approach was undertaken whereby probability distributions to the specified ranges for the key input parameters were assigned and 1000 Monte Carlo samples made from the input parameters. In an extension of the above model, an economic modelling framework was also used to predict the number of cases of pressure ulcer avoided, number of bed days not lost to pressure ulcer and economic costs if an intensive nutrition support intervention was provided to all nutritionally at risk patients in Queensland public hospitals in 2002/2003 compared to standard care. In addition to the above input parameters, data was obtained on the change in risk in developing a pressure ulcer associated with an intensive nutrition support intervention compared to standard care. The annual monetary cost of the provision of an intensive nutrition support intervention to at risk patients was modelled at a cost of AU$ 3.8-$5.4 million for additional food and nutritional supplements and staffing resources to assist patients with nutritional intake. A probabilistic sensitivity analysis approach was again taken. A mean of 34.7 + 4.0% and 31.4 + 9.5% of acute subjects and a median of 50.0% and 49.2% of residents of aged care facilities were found to be malnourished in Audits 1 and 2, respectively. Variables found to be significantly associated with an increased odds risk of malnutrition included: older age groups, metropolitan location of facility and medical specialty, in particular oncology and critical care. Malnutrition was found to be significantly associated with an increased odds risk of having a pressure ulcer, with the odds risk increasing with severity of malnutrition. In acute facilities moderate malnutrition had an odds risk of 2.2 (95% CI 1.6-3.0, p<0.001) and severe malnutrition had an odds risk of 4.8 (95% CI 3.2-7.2, p<0.001) of having a pressure ulcer. The overall adjusted odds risk of having a pressure ulcer when malnourished (total malnutrition) in an acute facility was 2.6 (95% CI 1.8-3.5, p<0.001). In residential facilities, where the audit results were presented separately, the same pattern applied with moderate malnutrition having an odds risk of 1.7 (95% CI 1.2-2.2, p<0.001) and 2.0 (95% CI 1.5-2.8, p<0.001); and severe malnutrition having an odds risk of 2.8 (95% CI1.2-6.6, p=0.02) and 2.2 (95% CI 1.5-3.1, p<0.001), for Audits 1 and 2 respectively. There was no statistical difference between these odds risk ratios between the audits. The overall adjusted odds risk of having a pressure ulcer when malnourished (total malnutrition) in a residential aged care facility was 1.9 (95% CI 1.3-2.7, p<0.001) and 2.0 (95% CI 1.5-2.7, p<0.001) for Audits 1 and 2 respectively. Being malnourished was also found to be significantly associated with an increased odds risk of having a higher stage and higher number of pressure ulcers, with the odds risk increasing with severity of malnutrition. The economic model predicted a mean of 3666 (Standard deviation 555) cases of pressure ulcer attributable to malnutrition out of a total mean of 11162 (Standard deviation 1210), or approximately 33%, in Queensland public acute hospitals in 2002/2003. The mean number of bed days lost to pressure ulcer that were attributable to malnutrition was predicted to be 16050, which represents approximately 0.67% of total patient bed days in Queensland public hospitals in 2002/2003. The corresponding mean economic costs of pressure ulcer attributable to malnutrition in Queensland public acute hospitals in 2002/2003 were estimated to be almost AU$13 million, out of a total mean estimated cost of pressure ulcer of AU$ 38 526 601. In the extension of the economic model, the mean economic cost of the implementation of an intensive nutrition support intervention was predicted to be a negative value ( -AU$ 5.4 million) with a standard deviation of $AU3.9 million, and interquartile range of –AU$ 7.7 million to –AU$ 2.5 million. Overall there were 951 of the 1000 re-samples where the economic cost is a negative value. This means there was a 95% chance that implementing an intensive nutrition support intervention was overall cost saving, due to reducing the cases of pressure ulcer and hospital bed days lost to pressure ulcer. This research program has demonstrated an independent association between malnutrition and pressure ulcers, on a background of a high prevalence of malnutrition, providing evidence to justify the elevation of malnutrition to a safety and quality issue for Australian healthcare organisations, similarly to pressure ulcers. In addition this research provides preliminary economic evidence to justify the requirement for consideration of healthcare policy, standards and guidelines regarding systems to identify, prevent and treat malnutrition, at least in the case of pressure ulcers in Australia.
32

Economic valuation of sport-fishing in Sweden : empirical findings and methodological development /

Paulrud, Anton, January 2004 (has links) (PDF)
Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv. / Härtill 5 uppsatser.
33

The landscape of landscape values : conceptual and empirical interpretation of economic values in landscape valuation /

Holstein, Fredrik, January 2006 (has links) (PDF)
Licentiatavhandling Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 2 uppsatser.
34

DEVELOPMENT OF AN AUTOMATION AND CONTROL SYSTEM FOR A COAL SPIRAL

Zhang, Baojie 01 December 2011 (has links)
Coal spirals are widely used in coal preparation plants around the world to clean fine coal, typically in the 1 x 0.15 mm size range. Despite their popularity and the trend toward increased automation in modern coal preparation plants, adjustments to the critical process variable for coal spirals, i.e., product splitter position, continue to be done manually. Since spiral feed in a plant tends to fluctuate on a regular basis, timely manual adjustment of splitter position in tens or hundreds of spirals operating in a plant is nearly impossible. As a result, the clean coal yield from a spiral and also the overall plant suffers on a regular basis. The main goal of this study was to develop a suitable sensor and control system to adjust the product splitter position of a full-scale spiral. Some of the basic properties of coal slurry were thoroughly investigated for their on-line measurability and for their correlations with the density of the constituent solid particles. After experimenting with electrical capacitance- and conductivity- (i.e., reciprocal of resistivity) based sensing techniques, a conductivity-based tube sensor was developed for measuring density of solid particles in the spiral trough. Two sensors were used to establish a density gradient in the critical region across the spiral trough at the discharge end. Based on this continuously monitored density gradient, a PIC24 microcontroller was programmed to send a signal to a DC gear motor that would move the splitter arm in the appropriate direction when sufficient variation in conductivity was detected. Currently, a cycle time of 5 minutes is used for the spiral control system; however, in a commercial application, the cycle time could be lengthened to 30 or 60 minutes. The automation system has been validated by examining the performance of a full-scale spiral while deliberately changing factors like feed solid content, feed washability characteristics, and feed slurry ionic concentration. With a full-scale compound spiral programmed to achieve a specific gravity of separation at 1.65 by an automatic adjustment of the splitter position, the actual D50 values achieved for two separate tests were 1.64 and 1.73. The close proximity of target and actual D50 values is indicative of the effectiveness of the developed system. The next step in near-term commercialization of this proprietary spiral control system will be a longer term (several months) in-plant demonstration. The main goal of this study was to develop a suitable sensor and control system to adjust the product splitter position of a full-scale spiral. One of the basic properties of coal slurry was thoroughly investigated for its on-line measurability and for its correlation with the constituent solid density of the slurry. After experimenting with electrical capacitance- and conductivity- (i.e., reciprocal of resistivity) based sensing techniques, a conductive-based tube sensor was selected for measuring solids density of particles in the spiral trough. Two sensors were used to establish a density gradient in the critical region across the spiral trough at the discharge end. Based on this continuously monitored density gradient, a PIC24 microcontroller was programmed to send a signal to a DC gear motor that would move the splitter arm when sufficient variation in conductivity was detected. Currently, a cycle time of 5 minutes is used for the spiral control system; however, in a commercial application, the cycle time could be lengthened to 30 or 60 minutes. The automation system has been validated by examining the performance of a full-scale spiral while deliberately changing factors like feed solid content, feed washability characteristics, and feed slurry ionic concentration. With compound spirals programmed to achieve a specific gravity of separation at 1.65, actual D50 values achieved for two separate tests were 1.64 and 1.73. The close proximity of target and actual D50 values is indicative of the effectiveness of the developed system. The next step in near-term commercialization of this proprietary spiral control system will be a longer term (several months) in-plant demonstration.
35

An economic analysis of the value of grazing winter cover crops

Higgins, Todd R. January 1900 (has links)
Master of Agribusiness / Department of Agricultural Economics / Jason S. Bergtold / Cover crops can be used as forage for cattle and other grazing animals. This research investigated the net returns of using cover crops for forage or grazing under four scenarios. These scenarios were: 1) a mixed crop and livestock producer who owns a herd of cattle and has both dry or pregnant cows and weaned calves available to graze corn stover and cover crops; 2) a crop farmer who purchases stocker cattle for the purpose of grazing the cover crop and corn stover; 3) a crop farmer who leases out a corn stover and cover crop field to a livestock producer (and who provides value-added services to the livestock producer for a fee); and 4) an integrated operation with crops and cattle where cover crops are not grown and hay is fed to cattle during the winter months. Each of these scenarios had different budgets, risks, and profit potentials. The research aimed to address the risks and profit potentials for each scenario. The stocking density was initially set at three cows and 31 steers for a period of 90 days, and alternatively, three cows and 25 steers for a period of 120 days. Two sets of cattle pricing data were used: the average historical prices from 1992 to 2011 and reported prices from a regional stockyard for the period of November 2016 to March 2017. The results showed that the initial stocking densities used for scenarios one and two were too low to provide profitable net returns regardless of pricing data used. Net returns for scenario three were also not profitable based on the services rendered and the management fee charged. Scenario four was profitable on one occasion. November steers with a 500 lb. average starting weight fed hay and concentrate for 120 days resulted in a positive net return of $375. A second analysis was done using stocking rates of 50, 75, or 100 steers to determine if increasing stocking density would result in a positive net return using only the 2016/2017 pricing data and only evaluating net returns on 2.0 and 2.5 lbs. of average daily gain. Positive net returns were achieved at various start weights and average daily gain rates at stocking rates of 75 and 100 animals. No positive net returns were realized at the stocking rate of 50 animals/100 acre field. The management fee charged for providing management services under scenario three was adjusted based on stocking densities to determine if a positive net return could be achieved at the set fee rate of $0.875/head/day. At that rate, no stocking rate resulted in a positive net return. Using the cost data, less the $900 field lease income, a breakeven pricing point for the management fee was determined for each stocking density and grazing duration within the scenario. Management of cost factors to achieve greater chances of profitability and additional research needs are discussed.
36

A stochastic techno-economic analysis of aviation biofuels production from pennycress seed oil

Jeremiah H Stevens (8081624) 14 January 2021 (has links)
<p>Much of current interest in aviation biofuels centers on trying to curb emissions of carbon dioxide and other greenhouse gases (GHGs) [1]. The problem is that the alternative aviation fuels which have been developed so far are not economically viable without policy supports and are underwhelming in regards to their environmental sustainability. The objective of this research is to identify biofuel pathways that perform better economically and environmentally than those which have been developed thus far. This paper will pursue this objective by examining the economic performance of a CH pathway fed by field pennycress under a number of possible scenarios.</p> <p>We conduct a stochastic discounted cash flow techno-economic analysis (TEA) of a plant designed to use catalytic hydrothermolysis (CH) technology to produce renewable diesel fuel, renewable jet fuel, and renewable naphtha from pennycress seed oil on a “greenfield” site under sixteen different scenarios defined by plant location, stage of commercialization, choice of fuel product slate, and policy environment. We combine process parameters such as conversion efficiencies, heat and water requirements, and capital costs for our model plant with stochastic projections of key input and output prices in order to model the distribution of possible financial outcomes for the plant over a twenty-year productive life. Our work follows McGarvey and Tyner (2018) in many respects, but uses updated process parameters from Applied Research Associates, Inc. (ARA), connects with economic analyses of the potential pennycress oil supply chain, and includes novel approaches to modeling key policies (US Renewable Fuel Standard, California Low Carbon Fuel Standard, and US Biodiesel Blender Tax Credit) and price series (US No. 2 diesel fuel, soybean oil, and dried distiller’s grains with solubles) [2]. Our output metrics include distributions of Net Present Values (NPVs), Probabilities of Loss (POLs), and distributions of Breakeven Prices (BEPs) for key inputs and outputs.</p> <p>Our results show that aviation biofuels production at a greenfield CH plant fed by pennycress seed oil is not economic under current market and policy conditions. Our breakeven metrics for a renewable jet fuel policy incentive, crude oil prices, and the input cost of pennycress oil indicate this could change if one of the following were to occur: </p> <p>· A crude oil price increase of at least 31-52%</p> <p>· A jet fuel price increase of at least 11-26%</p> <p>· A pennycress oil price discount of 2-6% from soybean oil prices</p> <p>· Some combination of the above</p> <p>These findings are heavily influenced by current policy design.</p>
37

Kogenerační jednotky pro domácí využití / Domestic CHP units

Paděra, Jiří January 2008 (has links)
The topic of this diploma study is to compile an overview of Domestic CHP units. The work is divided into three sections. The first section includes a summary of suitable CHP units. The second portion discusses the advantages and disadvantages of the individual chp units and the last segment describes the TEDOM Micro T8 chp unit, its possible integration in a family house, and its economic analysis.
38

Mikrokogenerace pro malé obytné objekty / Mikrokogeneration for small rezidential buildings

Opluštil, Marek January 2009 (has links)
The topic of this diploma study is to compile an overview of Domestic CHP units. The work is divided into three sections. The first section includes a summary of suitable CHP units. The second portion discusses the possibly methods of accumulation heat and electrical energy exploitable connection with CHP units. Last part of thesis is devoted to study apply CHP units in power supplyes choice object.
39

Optimal placement and effect of a wind farm on load flow and protection systems in a municipal distribution network

Martin, Mogamat Noer 28 January 2020 (has links)
Much research has been done on the effects of distributed generation on network characteristics. However, little research has been done on the effects of this distributed generation on current network protection schemes. An IPP has approached a South African municipality regarding the connection of a wind farm that would be connected to the municipality’s existing grid. This presented a unique opportunity to simulate and study the impact and effect that this wind farm would have on a real-life network in terms of network operation and protection schemes. This also presents the possibility of connecting the wind farm in a different configuration, possibly resulting in better network operation at a lower cost. The network optimisation in this research was done using the probability-based incremental learning (PBIL) and differential evolution (DE) optimisation techniques. These algorithms were programmed and modelled according to the desired IPP wind farm requirements using the MATLAB and MATPOWER simulation packages. The networks used in these algorithms were modelled in the text-based MATPOWER format. This research goes on to study a modified 14-bus IEEE test network in terms of network characteristics and protection performance so that an idea of the performance of the optimisation algorithms can be obtained. Protection data for the IEEE network was not available. The network was thus graded for use in this study. The research then continues to model the existing and proposed network configuration, and proposes various other points of connection to the municipal network using the PBIL and DE algorithms. These studies were conducted using the DIgSILENT PowerFactory simulation package, with the networks and protection data being modelled in this package. Network and protection performance results were recorded for each case in both networks under study. The results show that in the case of the modified IEEE network, the DE algorithm provides a better solution in terms of improving power losses while the PBIL algorithm provides a better solution in terms of improving the voltage profile. In the case of the municipality network, the DE algorithm provides the best performance, with the DE result managing to reduce power losses by 83.89% compared to the current and proposed network configurations. The overall voltage profile was also seen to improve by over 23%. The research also found that the change in fault level for the various cases are minimal. This is due to the limitation in fault current contribution imposed by the use of an inverter system connecting the wind farm to the grid. This means that, as the results shows, network grading is not very much affected by the addition of the wind farm connections. However, it is seen that the municipal network is not optimally graded in the base case. Finally, it is also seen that, though not often used in research, the MATPOWER package works well as a network simulation tool. A costing analysis was also conducted and shows that the DE solution is the most cost-effective solution, in addition to being the best-performing solution. The study recommends that the results produced by the DE algorithm be implemented instead of the proposed implementation. The municipal network should also be regraded and new protection settings should be implemented.
40

An Economic Analysis of Farm Tenure in the Uintah Basin, Utah

Johnson, Glen B. 01 May 1937 (has links)
Before presenting an economic analysis of farm tenure in the Uintah Basin, it will be helpful to consider some aspects of the historical, economic, and social background of that portion of the region included in this study. A portion of the Uintah Indian Reservation, which was created in 1861, was opened to white settlement under the homestead and townsite laws on August 28, 1905 after 103,000 acres of farming land had been allotted to individual Indians living on the reservation and 276,000 acres reserved for Indian grazing lands and timber reserve. Because of the large deposits of asphalt products that had been found nearby and a belief that the mountains were rich in minerals, much attention was attracted to this homestead opportunity. As a result 37,702 persons applied for entry of which it was estimated there would be land for only 5,772 when final drawings were made. Although this region seemed to be an "Eldorado" at that time it has later become one of the greatest problem areas of the State of Utah.

Page generated in 0.0739 seconds