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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.
441

Cost of Producing Field Crops in the Salt River Valley, Arizona

Clark, S. P. 01 October 1931 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
442

Analytical Scenario of Software Testing Using Simplistic Cost Model

Bathla, Rajender, Kapil, Anil 15 February 2012 (has links)
Software testing is the process of executing a program with the intention of finding errors in the code. It is the process of exercising or evaluating a system or system component by manual automatic means to verify that it satisfies specified requirements or to identify differences between expected and actual results [4]. Software Testing should not be a distinct phase in System development but should be applicable throughout the design development and maintenance phases. ‘Software Testing is often used in association with terms verification & validation ‘Software testing is the process of executing software in a controlled manner, in order to answer the question: Does the software behave as specified. One way to ensure system‘s responsibility is to extensively test the system. Since software is a system component it requires a testing process also. / Software can be tested either manually or automatically. The two approaches are complementary: automated testing can perform a huge number of tests in short time or period, whereas manual testing uses the knowledge of the testing engineer to target testing to the parts of the system that are assumed to be more error-prone. Despite this contemporary, tools for manual and automatic testing are usually different, leading to decreased productivity and reliability of the testing process. Auto Test is a testing tool that provides a “best of both worlds” strategy: it integrates developers’ test cases into an automated process of systematic contractdriven testing. This allows it to combine the benefits of both approaches while keeping a simple interface, and to treat the two types of tests in a unified fashion: evaluation of results is the same, coverage measures are added up, and both types of tests can be saved in the same format. The objective of this paper is to discuss the Importance of Automation tool with associate to software testing techniques in software engineering. In this paper we provide introduction of software testing and describe the CASE tools. The solution of this problem leads to the new approach of software development known as software testing in the IT world. Software Test Automation is the process of automating the steps of manual test cases using an automation tool or utility to shorten the testing life cycle with respect to time.
443

Switching Costs in the Market for Medicare Advantage Plans

Nosal, Kathleen Elizabeth January 2012 (has links)
Medicare eligibles have the option of choosing from a menu of privately administered managed care plans, known as Medicare Advantage (MA) plans, in lieu of conventional fee-for-service Medicare coverage ("original Medicare"). These plans often provide extra benefits to enrollees, but may impose large switching costs as a result of restrictive provider networks, differences in coverage across plans, and learning and search costs. I propose a structural dynamic discrete choice model of how consumers who are persistently heterogeneous make the choice among MA plans and original Medicare based on the characteristics of the available MA plans. The model explicitly incorporates a switching cost and changes over time in choice sets and plan characteristics. I estimate the parameters of the model, including the switching cost, using the methods developed by Gowrisankaran and Rysman (2011). The estimates indicate that the switching cost is statistically and economically significant. Through a series of counterfactual analyses, I find that the share of consumers choosing MA plans in place of original Medicare would more than triple in the absence of switching costs, and nearly double if plan exit and quality changes were eliminated. I also find that when switching costs are accounted for the Medicare Advantage program only minimally increases consumer welfare.
444

The applicability of case-based reasoning to software cost estimation.

January 2002 (has links)
The nature and competitiveness of the modern software development industry demands that software engineers be able to make accurate and consistent software cost estimates. Traditionally software cost estimates have been derived with algorithmic cost estimation models such as COCOMO and Function Point Analysis. However, researchers have shown that existing software cost estimation techniques fail to produce accurate and consistent software cost estimates. Improving the reliability of software cost estimates would facilitate cost savings, improved delivery time and better quality software developments. To this end, considerable research has been conducted into finding alternative software cost estimation models that are able produce better quality software cost estimates. Researchers have suggested a number of alternative models to this problem area. One of the most promising alternatives is Case-Based Reasoning (CBR), which is a machine learning paradigm that makes use of past experiences to solve new problems. CBR has been proposed as a solution since it is highly suited to weak theory domains, where the relationships between cause and effect are not well understood. The aim of this research was to determine the applicability of CBR to software cost estimation. This was accomplished in part through the thorough investigation of the theoretical and practical background to CBR, software cost estimation and current research on CBR applied to software cost estimation. This provided a foundation for the development of experimental CBR software cost estimation models with which an empirical evaluation of this technology applied to software cost estimation was performed. In addition, several regression models were developed, against which the effectiveness of the CBR system could be evaluated. The architecture of the CBR models developed, facilitated the investigation of the effects of case granularity on the quality of the results obtained from them. Traditionally researchers into this field have made use of poorly populated datasets, which did not accurately reflect the true nature of the software development industry. However, for the purposes of this research an extensive database of 300 software development projects was obtained on which these experiments were performed. The results obtained through experimentation indicated that the CBR models that were developed, performed similarly and in some cases better than those developed by other researchers. In terms of the quality of the results produced, the best CBR model was able to significantly outperform the estimates produced by the best regression model. Also, the effects of increased case granularity was shown to result in better quality predictions made by the CBR models. These promising results experimentally validated CBR as an applicable software cost estimation technique. In addition, it was shown that CBR has a number of methodological advantages over traditional cost estimation techniques. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.
445

Optimal operation of a water distribution network by predictive control using MINLP.

Biscos, Cedric P. G. January 2004 (has links)
The objective of this research project is to develop new software tools capable of operational optimisation of existing, large-scale water distribution networks. Since pumping operations represent the main operating cost of any water supply scheme, the optimisation problem is equivalent to providing a new sequence for pumping operations that makes better use of the different electricity tariff structures available to the operators of distribution systems. The minimisation of pumping costs can be achieved by using an optimal schedule that will allow best use of gravitational flows, and restriction of pumping to low-cost power periods as far as possible. A secondary objective of the operational optimisation is to maintain the desired level of disinfectant chlorine at the point of delivery to consumers. There is a steady loss of chlorine with residence time in the system. If the level drops too low there is a risk of bacterial activity. Re-dosage points are sometimes provided in the network. Conversely, too high a level produces an unacceptable odour. The combinatation of dynamic elements (reservoir volumes and chlorine concentration responses) and discrete elements (pump stati and valve positions) makes this a challenging Model Predictive Control (MPC) and constrained optimisation problem, which was solved using MINLP (Mixed Integer Non-linear Programming). The MINLP algorithm was selected for its ability to handle a large number of integer choices (valves open or shut / pumps on or off in this particular case). A model is defined on the basis of a standard element, viz. a vessel containing a variable volume, capable of receiving multiple inputs and delivering just two outputs. The physical properties of an element can be defined in such a way as to allow representation of any item in the actual network: pipes (including junctions and splits), reservoirs, and of course, valves or pumps. The overall network is defined by the inter-linking of a number of standard elements. Once the network has been created within the model, the model predictive control algorithm minimises a penalty function on each time-step, over a defined time horizon from the present, with all variables also obeying defined constraints in this horizon. This constrained non-linear optimization requires an estimate of expected consumer demand profile, which is obtained from historical data stored by the SCADA system monitoring the network. Electricity cost patterns, valve positions, pump characteristics, and reservoir properties (volumes, emergency levels, setpoints) are some of the parameters required for the operational optimisation of the system. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2004.
446

Costs and Benefits of Nature-Based Tourism to Conservation and Communities in the Serengeti Ecosystem

Masuruli, Masuruli Baker 05 January 2015 (has links)
People visit protected areas (PAs) for enjoyment and appreciation of nature. However, tourism that is not well planned and managed can significantly degrade the environment, and impact negatively on nearby communities. Of further concern is the distribution of the costs and benefits of nature-based tourism (NBT) in PAs, with some communities experiencing proportionally more benefits, while other communities experience more of the cost. This distribution is complex and differs considerably amongst PAs. This thesis examines the flow and distribution of the costs and benefits of the NBT supply system to conservation and communities in the Serengeti ecosystem, Tanzania. The Serengeti ecosystem, a World Heritage site and a leading global wildlife tourism destination, was selected for this study because of high biodiversity, high poverty, and a high level of NBT activity. The research was guided by four main questions: (1) what is the nature of the supply system of NBT in the Serengeti ecosystem; (2) how do the management plans allow for and guide tourism in the Serengeti ecosystem; (3) what are the impacts of the NBT supply system on conservation; and, (4) what are the impacts of the NBT supply system on communities? A qualitative approach was used, combining document analysis, key informant interviews, and focus group discussions. This involved collecting data from a number of participants: PA agencies; the tourism industry; nearby communities; and non-governmental organizations. Participants were recruited through purposive and snowball sampling techniques. The findings offer an ecosystem-scale perspective rather than the common focus on a single PA. The study uses complex systems theory to help frame the NBT supply system in the Serengeti ecosystem, which is comprised of numerous agents that can be grouped in four major components − PAs, communities, tourism operations, and elements of the wider environment. The agents, such as tour operators, park management, and communities, vary across the ecosystem, and have multiple roles in NBT, including management of attractions, tourism planning and management, and provision of accommodation, transportation, accessibility, information, security, and utilities. There are complex interactions and relationships among these components across the ecosystem, and at local, regional, national, and international scales. PAs interact with tourism operators, PAs interact with communities, tourism operators interact with communities, and the three components are linked to the wider environment. These components of the NBT supply system interact dynamically in a non-linear manner, resulting in mixed outcomes for conservation and communities. The findings indicate the need for an integrated management approach to NBT in the Serengeti ecosystem that is more adaptive and ecosystem-based than currently exists. The wildlife legislation requires all PAs in the Serengeti ecosystem to have management plans, but some do not. The management plans in the ecosystem vary among PAs, with a number of flaws, including inadequate participation of stakeholders, poor use of zoning (design and implementation), and ineffective application of the “Limits of Acceptable Use” (LAU) as a main framework for controlling use. Management can be improved by several measures, including more effective inclusion of stakeholders, and application of the “Limits of Acceptable Change” (LAC) rather than “LAU,” amongst other measures that are outlined in more detail below. NBT in the Serengeti ecosystem is growing, and delivers a range of conservation benefits and costs that vary across the ecosystem. These conservation benefits include: financial support for conservation, improved biodiversity conservation and PA management, raised conservation awareness, and public support for conservation. These benefits can be improved by enhancing the quality of services and tourism experience, charging appropriate fees, PA agencies retaining a portion of tourism revenue, and improving collaboration and participation of stakeholders in NBT and conservation. Conservation costs include financial costs, wildlife disturbance, shifting priorities from conservation to tourism, habitat destruction, and pollution. These costs can be reduced by undertaking thorough investigation of the potential costs and benefits of tourism development, effective management planning, improving provision of information to tourists, and improving NBT management. NBT delivers many benefits to communities, such as income, employment, social services and infrastructure, scholarships, and school fees. These benefits can be improved by participation of local communities in conservation, promoting capacity building in local communities, improving legislation and mechanisms governing delivery of benefits, and encouraging communities to establish Wildlife Management Areas (WMAs). NBT results in many costs to local communities, such as loss of grazing land and farmland, conflict (tourism stakeholders, and human-wildlife conflicts), stress to local residents due to increase of human populations, and unintended consequences such as cultural degradation. These costs can be reduced by involving local communities in tourism development and management and developing codes of conduct for tourism operators and PA agencies. Specific examples of suggested actions include: developing and implementing effective management plans; promoting stakeholder awareness of conservation, NBT, and communities; and establishing a forum for discussing interests and issues of stakeholders in the ecosystem. The flow and distribution of these costs and benefits to conservation and communities also varies across the Serengeti ecosystem. Overall, NBT generates substantial benefits to PAs, although considerably less revenue is allocated to conservation activities than is accrued from NBT. On the other hand, local communities experience considerable costs and receive inadequate benefits that are not sufficient to address poverty. Inadequate mechanisms that govern the flow of the costs and benefits, poor governance, and persistent poverty are some of the main factors contributing to the imbalance of the flow and distribution of the costs and benefits of NBT. Finally, a complex systems perspective was shown to be a useful tool in understanding the NBT system as a whole, the dynamic interaction within the system and beyond, and associated costs and benefits delivered by that system. Overall, this study recommends adaptive management, ecosystem-based management, and an integrated approach that recognizes and accommodates the interests of various NBT stakeholders in the Serengeti ecosystem. Specific actions of high priority include developing and implementing effective management plans, adopting LAC in PA planning, capacity building for communities to participate in the tourism industry, and participation and collaboration of NBT stakeholders in the ecosystem. / Graduate
447

Cross-sectional and longitudinal relationships between physical activity and health services utilization in community-dwelling older adults

2014 February 1900 (has links)
There has been a growing interest among policymakers in the potential role of physical activity (PA) as a strategy to mitigate the challenges associated with an aging population, specifically the potential pressures on the health care system presented by an increasing need and demand for long term management of chronic health conditions. In this dissertation, the relationship between PA and health service utilization among older adults and the role of PA in reducing health services utilization in this population is examined via two studies. Study 1: The purpose of Study 1 was to examine relationships between LTPA and health services utilization in a nationally representative sample of community-dwelling adults aged 50 years and older. Methods: This study involved a secondary analysis of data from the Cycle 3.1 of the Canadian Community Health Survey. The analysis was restricted to individuals aged 50 years and older, resulting in an unweighted sample of 56,652 adults (48%M; 52%F; mean age 63.5±10.2 years), stratified a priori into three age groups (50 – 64 years, 65 – 79 years, 80 years and older). Self-reported use of general physician (GP) services, specialist physician services and hospital services for the 12-month period prior to the survey were the outcomes of interest. The main independent variable of interest was self-reported LTPA for a 3-month period prior to the survey. A comprehensive set of predisposing, enabling, and health need factors associated with health services utilization were included as control variables in all analyses. Separate multiple logistic and negative binomial regression models were used to assess the association between LTPA and each dichotomous and count-based dependent variable, respectively. Bootstrap re-sampling procedures were applied in all regression analyses. Results In the 50-64 year age group, active individuals were 27% less likely to report any contact with a GP (OR=0.73; p<.001) and had 8% fewer GP consultations (IRR=0.92; p<.01) than their inactive counterparts. Among 65 to 79 year olds, active respondents were 18% less likely than their inactive counterparts to have had an overnight hospitalization in the previous 12 months (OR=0.82, p<.05). Across all age groups, higher levels of non-leisure physical activity was associated with lower health services utilization. Study 2: The purpose of Study 2 was to investigate the effects of a randomized community-based PA intervention (50+ in motion) on participants’ health service utilization and healthcare costs over a 5-year period. Methods: 50+ in motion was a randomized clinical trial comparing the effectiveness of a class-based (CB) and home-based (HB) exercise program for older adults with select chronic health conditions (hypertension, dyslipidemia, type 2 diabetes mellitus, osteoarthritis, overweight or obesity). Of the 172 participants randomized, 59 CB and 69 HB participants granted access to their administrative health data. Data pertaining to GP and specialist physician services utilization and costs as well as hospital services utilization and costs were obtained for all consenting participants from the Saskatchewan Ministry of Health for the year prior to enrolment in the 50+ in motion study through to 48-months post-randomization, for a total of 5-years of data. Independent variables including demographic characteristics, physical activity, sedentary behaviour, cardiovascular endurance, functional fitness, body composition, blood pressure, and self-reported physical and mental health status were collected directly from participants prior to randomization and then annually for 4 years. Longitudinal effects of the 50+ in motion intervention on health services utilization and healthcare costs were assessed using the generalized estimating equation (GEE) approach with covariates selected for inclusion based on methods of purposeful selection. Results: There were no significant differences in health services utilization or health care costs between the CB and HB interventions until the final year of the study when the HB group had 60% more GP visits than the CB group and were 89% less likely than the CB group to be frequent users of specialist services. There were no significant differences between the randomization groups in healthcare costs. Measures of functional fitness emphasizing lower body strength, endurance and power were more consistently associated with lower health services utilization than CV endurance, body composition or physical activity. Sedentary behavior was associated with higher hospital costs, independent of physical activity, functional fitness and health status. Overall Conclusion: Taken together, the two studies in this thesis address a significant gap in the Canadian literature and provide novel insights into the relationships between PA, health and health services utilization in older adults. While further research is needed to improve our understanding of the relationships between physical activity and sedentary behaviour, physical fitness, and health services utilization, the findings presented in this thesis suggest reducing sedentary behaviour and improving functional fitness in older adults may be as important as physical activity, if not more so, in terms of potential impact on health services utilization and health care costs. For health care professionals and policymakers at all levels, the findings highlight the advantages of a multi-pronged, interdisciplinary approach to the development of public health initiatives and interventions focused on increasing PA participation and functional fitness among older adults.
448

Woodfuel supply chain integration in the South West of England : a transaction costs approach to bioenergy development

Garzon Delvaux, Pedro Andres January 2011 (has links)
The wood energy market remains nascent in the UK, despite climate change policies and energy security concerns. Transaction costs have been identified as one barrier to woodfuel development. However, few studies provide explicit insights into such barriers to spontaneous exchange in this sector and how they influence its formation. The study approaches the development of woodfuel in the South West Region of England through Transaction Costs Economics (TCE) and aims to identify the appropriate governance structure of the supply chain as a response to existing transactions costs. When transaction costs increase, seamless market exchange gradually gives way to credible contracting and even to full vertical integration or unified ownership. The TCE approach provides insights to analyse friction and barriers to exchange and allows for a dialogue between economics, law and day-to-day business decision-making. Fuel procurement from woodfuel suppliers to woodfuel users is central to this project in looking at the barriers to exchange. Original data was collected through 42 in-depth interviews, mainly with suppliers themselves but also from Forestry Commission, regional agencies, NGOs and lobbies involved. The results suggest the influence of transaction costs. Also, there is some evidence that wood-energy regional actors are embracing organisational diversity from known rural business structures to less familiar ones in the UK, such as cooperatives and new partnerships as answers to, among other factors, transaction costs. The evidence suggests that not only support to demand and supply is necessary, as generally identified, but it is also needed at its interface by supporting the governance of the supply chain. Some practical implications for both public and private sectors are identified to better articulate the response to this need.
449

AN EXPERIMENTAL ANALYSIS OF ENVIRONMENTS WITH LARGE COMMON COSTS AND UNCERTAIN SUPPLIES: APPLICATIONS TO SPACE STATION

PORTER, DAVID PETER, PORTER, DAVID PETER January 1987 (has links)
Suppose we are confronted with an environment which consists of large common costs and uncertain supplies. Furthermore, suppose the resources in this environment are being supplied by a public enterprise monopoly which is interested in maintaining economic efficiency while recovering costs incurred by the project. Then the above problem becomes one of institutional design. Even if conditions existed in which traditional marginal cost pricing provided the proper signals for efficiency, additional charges will be necessary to recover costs due to the large common costs in this environment. Ideas and suggestions about decentralized methods of covering common costs lead naturally to questions about decentralized methods for solving the public goods provision problem. This paper reports in part on an experimental investigation of four methods for allocating public goods. The two basic processes studied are direct contribution and a public goods auction process. Both of these processes are studied with and without an additional unanimity feature. The results suggest that the auction process outperforms direct contribution. The effect of unanimity is to decrease the efficiency of both processes. Strategic aspects of the voting rule (unanimity) are evident in the results. To assist in the contingency planning for environments with uncertain supplies, different contract forms are considered. In particular, priority and contingent contracting are investigated along with specific mechanisms to allocate such contracts. An experimental environment is developed to investigate the various contract forms and mechanisms. The experiment considers two contract forms (contingent and priority) and four allocation mechanisms (Random, English auction, English auction with queue, and Iterative Groves). The experimental results show that bidding for priority results in higher efficiency than pre-assignments. Furthermore, allowing individuals to signal coalitional bids has a positive effect on efficiency and revenue generated.
450

Die voordeel wat doeltreffende en effektiewe toedeling van koste en produksie inhou vir prysdifferensiasie en die bestuur van trokdienste (Suid-Transvaal) as onderneming

29 September 2015 (has links)
M.A. (Economics) / The aim of this dissertation is to analyze industrial market demand in order to allow the management of Truck Services (Southern-Transvaal) to allocate cost and production efficiently and effectively. The implementation of a market driven capacity will ensure increased profit margins with expanded market shares. This is vital in an extremely competitive transport market ...

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