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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.
321

Near-Optimal Antenna Design for Multiple Antenna Systems

Evans, Daniel N. 06 March 2009 (has links) (PDF)
Multiple-input-multiple-output (MIMO) wireless systems use multiple antenna elements at the transmitter and receiver to offer improved spectral efficiency over traditional single antenna systems. In these systems, properties of the transmit and receive antenna arrays play a key role in determining the overall performance of the system. This thesis derives an upper bound on ergodic (average) channel capacity which formally links good antenna diversity performance with good ergodic capacity. As a result of this derivation, antenna arrays with good ergodic capacity performance are designed in this thesis by designing antenna arrays with near-optimal diversity gain. Several approaches are developed to design antenna array elements which achieve near-optimal diversity. These design methods only require an array geometry and the power azimuth spectrum of the propagation environment. Examples and analysis are included that illustrate advantages and disadvantages of each design technique. Three different array geometries are also investigated. Diversity performance results for each design technique and array geometry, averaged over an ensemble of typical power azimuth spectrums, are presented and compared. This analysis shows that the diversity gain achieved by the best design approach is, on average, less than 1.5 dB below the optimal diversity gain.
322

Successful Impoverished Schools: What are the Existing Conditions in High Poverty Schools That Have a Higher Than Average Proficiency Rate?

Nerdin, Mitchell Winn 08 August 2022 (has links)
Proficiency levels in schools often correlate with the poverty levels of schools. However, in 2018 three schools in Utah beat the state average proficiency rate on all three of Utah's end of year summative English language arts, mathematics, and science exams. These high scores provide evidence that schools are not necessarily limited by poverty in helping students succeed academically. By examining the schools that beat the state average on at least one exam, this study describes the conditions that were in play, which contributed to their students' academic achievement. A description is given of the conditions in the schools that are believed to produce high achievement. These conditions existed and these actions were taken to help a school with a high-poverty population break the perceived bond of poverty and low academic results to produce uncommonly high student achievement. This study identified the schools in Utah with a high poverty rate (70% or above) and also have student academic proficiency rates higher than the state average on at least one of the state assessments. The data indicates there are 80 schools with a high poverty rate. While only three of those schools had student academic proficiency rates on all three tests that were above average for the state of Utah, eight schools are included in the study as they had student academic proficiency rates above the state average on at least one test. This study reveals that these schools focus attention on school structures, positive school culture, leadership of the principal and his willingness to share leadership with teachers, improving instruction, and efficacious parent engagement. These things are the levers that helped move academic success forward in these schools, even though they are schools with a high rate of students experiencing poverty.
323

Determinants Of Financial Condition: A Study Of U.S. Cities

Dennis, Lynda 01 January 2004 (has links)
How well a local government is able to provide for the needs and preferences of its citizens generally depends on the financial resources available; and, how such resources are allocated, distributed, and managed. Demographics, size of local government, supply and age of infrastructure, financial position of the government, and the local economy represent a few of the factors affecting what public goods and services citizens prefer. Internal systems of accounting and control affect the allocation, distribution, and management of financial resources. As such, these internal systems significantly affect the provision of public goods and services. The research outlined in this study examined the relationship between a government's financial management capacity (independent variable) and its financial condition (dependent variable), while controlling for environmental factors related to governance and demographics. Financial condition was quantitatively measured using financial ratios calculated from a database of over 1,600 U.S. cities compiled by the Government Finance Officers Association. Financial management capacity and its relationship to financial condition were measured with a survey of the chief financial officers of almost 500 of the sample cities. This research was exploratory in nature as there is little empirical evidence with respect to financial management capacity or its relationship to overall financial condition. In this study certain statistically significant moderate correlations were found with respect to financial condition and financial management capacity. However, multiple regression analysis of financial condition and financial management capacity (controlling for governance and socio-economic factors), indicated no statistically significant relationship between them as conceptualized and operationalized for this study. When controlling for certain governance and socio-economic factors, annual limits on increases in assessed property valuations and population were found to be statistically significant with respect to financial condition. Additionally, these control variables increased and decreased financial condition, respectively. A major contribution made to the literature by this study lies in its attempt to establish an empirical relationship between financial management capacity and government performance as measured by financial condition. Based on existing literature as reviewed by this researcher, the testing of this relationship had not been done previously. This study defined and measured both financial management capacity and financial condition in dimensions and indicators that can be used in future research. Additionally, efforts were made to test the internal reliability of both measures. The results of this research indicated there are a number of other financial management capacity and environmental factors influencing financial condition beyond those identified in this study. This research also provided insight regarding the extent financial management capacity affects financial condition even though such relationships were not found to be statistically significant. Because no statistically significant relationships between financial condition and financial management capacity were found in this study, additional research is necessary to further explore this relationship as well as the correlation between the various indicators of these concepts.
324

Effectiveness of Web Reinforcement around Openings in Continuous Concrete Deep Beams.

Yang, Keun-Hyeok, Ashour, Ashraf 07 1900 (has links)
yes / Twenty two reinforced concrete continuous deep beams with openings and two companion solid deep beams were tested to failure. The main variables investigated were the configuration of web reinforcement around openings, location of openings, and shear span-to-overall depth ratio. The influence of web reinforcement on controlling diagonal crack width and load capacity of continuous deep beams with openings was significantly dependent on the location of openings. The development of diagonal crack width and load capacity of beams having openings within exterior shear spans were insensitive to the configuration of web reinforcement. However, for beams having openings within interior shear spans, inclined web reinforcement was the most effective type for controlling diagonal crack width and increasing load capacity. It has also observed that higher load and shear capacities were exhibited by beams with web reinforcement above and below openings than those with web reinforcement only above openings. The shear capacity at failed shear span of continuous beams tested is overestimated using Kong et al’s formula developed for simple deep beams with openings.
325

Structural Behaviour of Concrete-filled Elliptical Column to I-beam Connections

Yang, Jie January 2017 (has links)
Concrete-filled tubular (CFT) columns have been widely adopted in building structures owing to their superior structural performance, such as enhanced load bearing capacity, compared to hollow tubes. Circular, square and rectangular hollow sections are most commonly used in the past few decades. Elliptical hollow section (EHS) available recently is regarded as a new cross-section for the CFT columns due to its attractive appearance, optional orientation either on major axis or minor axis and improved structural efficiency. The state of the research in terms of elliptical columns, tubular joints between EHSs and connections with CFT columns, etc., are reviewed in this thesis, showing a lack of investigations on EHSs, especially on beam to elliptical column connections which are essential in framed structures. The structural behaviour of elliptical column to I-beam connections under bending is studied in this thesis to fill the research gap. Overall ten specimens with various joint assemblies were tested to failure to highlight the benefits of adopting concrete infill and stiffeners in the columns. A three-dimensional finite element model developed by using ABAQUS software is presented and verified against obtained experimental results, which shows acceptable accuracy and reliability in predicting failure modes of the connections and their moment capacities. Parametric studies were performed to access the main parameters that affecting the bending behaviour of the connections. A simple hand calculation method in terms of ultimate moment capacity is proposed according to experiments conducted for connections with concrete-filled columns.
326

Development of methods to determine the binding capacities of solid supports and improvement in immunoassay efficiency using dendrimer-modified beads

Tiwari, Umadevi B. January 2009 (has links)
No description available.
327

Capacity Modeling of Freeway Weaving Sections

Zhang, Yihua 27 June 2005 (has links)
The dissertation develops analytical models that estimate the capacity of freeway weaving sections. The analytical models are developed using simulated data that were compiled using the INTEGRATION software. Consequently, the first step of the research effort is to validate the INTEGRATION lane-changing modeling procedures and the capacity estimates that are derived from the model against field observations. The INTEGRATION software is validated against field data gathered by the University of California at Berkeley by comparing the lateral and longitudinal distribution of simulated and field observed traffic volumes categorized by O-D pair on nine weaving sections in the Los Angeles area. The results demonstrate a high degree of consistency between simulated and field observed traffic volumes within the various weaving sections. Subsequently, the second validation effort compares the capacity estimates of the INTEGRATION software to field observations from four weaving sections operating at capacity on the Queen Elizabeth Way (QEW) in Toronto, Canada. Again, the results demonstrate that the capacity estimates of the INTEGRATION software are consistent with the field observations both in terms of absolute values and temporal variability across different days. The error was found to be in the range of 10% between simulated and field observed capacities. Prior to developing the analytical models, the dissertation presents a systematic analysis of the factors that impact the capacity of freeway weaving sections, which were found to include the length of the weaving section, the weaving ratio (a new parameter that is developed as part of this research effort), the percentage of heavy vehicles, and the speed limit differential between freeway and on- and off-ramps. The study demonstrates that the weaving ratio, which is currently defined as the ratio of the lowest weaving volume to the total weaving volume in the 2000 Highway Capacity Manual, has a significant impact on the capacity of weaving sections. The study also demonstrates that the weaving ratio is an asymmetric function and thus should reflect the source of the weaving volume. Consequently, a new definition for the weaving ratio is introduced that explicitly identifies the source of the weaving volume. In addition, the study demonstrates that the length of the weaving section has a larger impact on the capacity of weaving sections for short lengths and high traffic demands. Furthermore, the study demonstrates that there does not exist enough evidence to conclude that the speed limit differential between mainline freeway and on- and off-ramps has a significant impact on weaving section capacities. Finally, the study demonstrates that the HCM procedures model the heavy duty vehicle impacts reasonably well. This dissertation presents the development of new capacity models for freeway weaving sections. In these models, a new definition of the weaving ratio that explicitly accounts for the source of weaving volume is introduced. The proposed analytical models estimate the capacity of weaving sections to within 12% of the simulated data, while the HCM procedures exhibit errors in the range of 114%. Among the newly developed models, the Artificial Neural Network (ANN) models performs slightly better that the statistical models in terms of model prediction errors. However, the sensitivity analysis results demonstrate unrealistic behavior of the ANN models under certain conditions. Consequently, the use of a statistical model is recommended because it provides a high level of accuracy while providing accurate model responses to changes in model input parameters (good response to the gradient of the input parameters). / Ph. D.
328

Exploring the Structure and Development of Management Prescriptions for Public Lands

Cahill, Kerri Lynn 18 November 2003 (has links)
Management prescriptions that describe desired conditions for resources and visitor experiences have become widely accepted as an important component of public land management plans. However, very little effort is spent on evaluating and learning about this part of the planning process. This research identifies and addresses the need to explore opportunities for additional guidance on the development of management prescriptions, by (1) evaluating the current perception of the purpose of management prescriptions; (2) developing criteria and other tools to guide the development of management prescriptions based on the experiences of public land management professionals; and (3) testing an alternative method for collecting visitor preference data regarding social, resource and management conditions to inform development of management prescriptions. The first two papers report the results of a visitor preference study, using the stated choice method, conducted in Acadia National Park. The purpose of the first paper is to identify visitor preferences for tradeoffs among social, resource and related management conditions of the recreation setting. The purpose of the second paper is to identify differences among visitor preferences for social, resource and management conditions in various recreation settings. By considering the integrative nature of these attributes and the relative importance to visitors across recreation settings, the definition of management prescriptions can be better informed. To further investigate the results of the stated choice method and ensure the validity of the data, a verbal protocol assessment was applied to a sample of the stated choice survey respondents. The purpose of the third paper is to reexamine the role of management prescriptions for park management planning and investigate tools for facilitating development of management prescriptions. The study included in-depth interviews, participant observation of a three-day planning workshop and a written survey. All of the participants in the various components of the study were National Park Service land management professionals. The study resulted in a list of the purpose and criteria for management prescriptions and a related menu of desired condition topics, which will be integrated into planning guidance to aid the development of unique and effective management prescriptions for national parks. / Ph. D.
329

Determination of the Capacity Building Framework that Support a Collaborative Fruit and Vegetable Prescription Program

Schwartz, Olivia Rae 22 May 2017 (has links)
Over half of U.S. adults, roughly 117 million individuals, suffer from at least one preventable chronic disease, such as obesity, hypertension, coronary heart disease, and certain types of cancer. Epidemiological studies suggest that fruit and vegetable intake may be protective against these diseases, yet it is estimated that less than one-quarter of the population meets current fruit and vegetable recommendations. Low consumption rates may be attributed to lower income, food insecurity, and poor access and availability to fruits and vegetables. As a result, access to affordable and nutritious foods and beverages, particularly in underserved communities, such as “food deserts,” has become a national priority. An emerging strategy to address this is prescription programs, whereby physicians provide prescriptions or vouchers for fruit and vegetables to clients to encourage increased consumption, implemented in the form of the Farmacy Garden, which was the result of collaboration between multiple agencies. For collaborative efforts to be able to implement and sustain their shared goals, partnering individuals, agencies, and organizations need to first have the capacity or the potential to build capacity as a ‘unit.’ The purpose of this study was to concretely examine different factors and domains within Matachi’s Capacity Building Framework related to the Farmacy Garden in order to replicate the program in other locations. This framework conceptualizes organizational capacity building as dependent (and interdependent) on three different domains - individual, organizational, and environment. The study utilized semi-structured, openended interviews to ascertain concrete factors of organizational capacity building present at each level among Farmacy Garden collaborative project stakeholders (n=7). Interviews with six stakeholders (85.7% response rate) ranged in length from thirty-two minutes to one hour and twenty minutes. Common themes were coded separately by two members of the research team, first for overall recurring themes and second, to reveal connections between themes. Relevant quotes were identified and any discrepancies between researchers were resolved. Common themes often crossed over different levels, such as time, beliefs, values, and attitudes and inter-organizational linkages/partnerships, attitudes, and relationships, highlighting the inter-dependence of various factors across domains of capacity building. In addition to identifying specific factors that were necessary for the creation and sustainability of the Farmacy Program, the analysis revealed the importance of a “shared belief and value system.” In other words, individuals and organizations “valorized” this project in different ways than more traditional programs and/or interventions. The findings of this study can help guide leadership in cultivating relationships and new benchmarks to ensure transparency in project goals, in addition to time and physical resources, as well as inform the organizational capacity research area within nutrition and food systems fields. / Master of Science
330

Ethnography in Dementia Care Research: observations on ability and capacity

Ludwin, Katherine, Capstick, Andrea 30 September 2016 (has links)
No / This case outlines the rationale and methods used when carrying out ethnographic fieldwork in a care home environment with research participants who were living with a dementia diagnosis. Although concerns had been raised at ethics approval about the use of such methods – visual ethnography in particular – we found that there were ethical benefits for the participants whose capacity for research participation, and for social participation generally, was, in every case, higher than anticipated at the outset. By comparison we found that formal methods for assessing ability to give informed consent often appeared to create excess disability, and to exacerbate ill-being for people with dementia. The case draws on specific examples to show how issues related to methods and to ethical conduct of research are frequently intertwined, and should be considered together rather than in isolation.

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