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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.
171

MIMO channel modelling for indoor wireless communications

Maharaj, Bodhaswar Tikanath Jugpershad 29 July 2008 (has links)
This thesis investigates multiple-input-multiple-output (MIMO) channel modelling for a wideband indoor environment. Initially the theoretical basis of geometric modelling for a typical indoor environment is looked at, and a space-time model is formulated. The transmit and receive antenna correlation is then separated and is expressed in terms of antenna element spacing, the scattering parameter, mean angle of arrival and number of antenna elements employed. These parameters are used to analyze their effect on the capacity for this environment. Then the wideband indoor channel operating at center frequencies of 2.4 GHz and 5.2 GHz is investigated. The concept of MIMO frequency scaling is introduced and applied to the data obtained in the measurement campaign undertaken at the University of Pretoria. Issues of frequency scaling of capacity, spatial correlation and the joint RX/TX double direction channel response for this indoor environment are investigated. The maximum entropy (ME) approach to MIMO channel modelling is investigated and a new basis is developed for the determination of the covariance matrix when only the RX/TX covariance is known. Finally, results comparing this model with the established Kronecker model and its application for the joint RX/TX spatial power spectra, using a beamformer, are evaluated. Conclusions are then drawn and future research opportunities are highlighted. / Thesis (PhD)--University of Pretoria, 2008. / Electrical, Electronic and Computer Engineering / unrestricted
172

A Comparative Study of the Total Maximum Daily Load (TMDL) Program and Process in Virginia and Kansas: Possible Outcomes and Effects upon Stakeholders

Miller-McClellan, Jennifer Lynn 13 June 2003 (has links)
As population increases, the number of water bodies meeting water quality standards tends to decrease. The 1972 Clean Water Act (CWA) addresses the issues of point and nonpoint source pollution by requiring states to compose lists of waters that do not meet water quality standards and develop Total Maximum Daily Loads (TMDL) for those waters. This requirement of the CWA remained inactive until EPA and states suffered lawsuits from environmental groups and concerned citizens. The result prompted a flurry to develop TMDLs in compliance with consent decrees. A variety of methods and models serve as tools to calculate existing loads, load reductions and allocations. The purpose of this study is threefold 1) to examine two methods of TMDL development, Flow Duration (FD) used in Kansas and Hydrologic Simulation Program-Fortran (HSPF) used in Virginia; 2) to compare results of both methods in the same watershed of Virginia; and, 3) to evaluate stakeholder involvement in the TMDL process. A variety of stakeholders such as agencies, towns and industry, agribusiness, and concerned citizen/environmentalists are faced with meeting TMDL reductions and allocations. It is important that the TMDL process and implications are understood by all stakeholders. / Master of Public and International Affairs
173

The Effect of 5% Hypohydration on Muscle Cramp Threshold Frequency

Braulick, Kyle William January 2012 (has links)
Many clinicians believe exercise associated muscle cramps (EAMC) occur because of dehydration and electrolyte losses. Experimental research supporting this theory is lacking. Mild hypohydration (3% body mass loss) does not alter cramp threshold frequency (TF), a measure of cramp susceptibility, when fatigue and exercise intensity are controlled. No experimental research has examined TF following significant (3-5% body mass loss) or serious hypohydration (>5% body mass loss). TF and blood variables of ten subjects were measured pre-post exercise. Subjects exercised in an environmental heat chamber alternating between upper arm ergometry and non-dominant leg cycling every 15 minutes until they lost 5% of their body mass or were too exhausted to continue. Significant (n=5) or serious hypohydration (n=5) did not alter cramp TF, cramp intensity, or cramp EMG amplitude. Significant and serious hypohydration with moderate electrolyte losses does not alter cramp susceptibility when fatigue and exercise intensity are controlled.
174

Fixação de frutos no meloeiro : viabilidade polínica, receptividade estigmática e protocolos de polinização. /

Oliveira, Aline de January 2019 (has links)
Orientador: Leila Trevisan Braz / Resumo: Polinizações manuais na cultura do meloeiro apresentam taxa de sucesso de cerca de 40%, entretanto, pouco se relata na literatura sobre os aspectos que afetam esta taxa, tornando-a baixa, e como incrementa-la. Este trabalho teve por objetivo estudar a biologia reprodutiva do meloeiro, e estratégias para aumentar a taxa de pegamento de frutos na cultura. Para tal, foram estudados a viabilidade polínica e receptividade estigmática em genótipos de meloeiro ao longo do dia da antese, e, o impacto de diferentes protocolos de polinização na fixação de frutos. Desta forma, foram desenvolvidos três experimentos, um de viabilidade polínica in vitro, e um de receptividade estigmática, estes envolvendo três genótipos de melão rendilhado e cinco horários de coleta de flores, visando entender o comportamento floral do meloeiro ao longo do dia. E um terceiro trabalho, onde foi estudado a fixação de frutos, massa total e massa de mil sementes dos frutos formados sob diferentes protocolos de polinização, para tal empregou-se autopolinizações e hibridações, em dois horários e soluções diretamente nos estigmas da flor hermafrodita, com o objetivo de beneficiar a germinação e estrutura dos tubos polínicos, propiciando fecundações mais eficientes. Após as avaliações, os dados foram submetidos a análise estatística e comparados pelo teste de Tukey a 5% de significância. Foi possível concluir que a viabilidade polínica do meloeiro é afetada pelo genótipo, e os genótipos, JAB 11, JAB 20 e Fantasy, ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Manual pollination in melon crop has a success rate of about 40%, however, little is reported in the literature about the aspects that affect this rate, making it low, and how to increase it. This work aimed to study the reproductive biology of melon, and strategies to increase the fruit set rate in the crop. To this end, we studied the pollen viability and stigmatic receptivity in melon genotypes throughout the day of anthesis, and the impact of different pollination protocols on fruit fixation. Thus, three experiments were carried out, one with in vitro pollen viability and one with stigmatic receptivity, involving three tracery melon genotypes and five flower collection schedules, aiming to understand the floral behavior of melon throughout the day. And a third work, where the fruit fixation, total mass and mass of one thousand seeds of the fruits formed under different pollination protocols was studied. in order to benefit the germination and structure of pollen tubes, providing more efficient fertilization. After the evaluations, the data were submitted to statistical analysis and compared by Tukey test at 5% of significance. It was concluded that the pollen viability of melon is affected by genotype, and the genotypes, JAB 11, JAB 20 and Fantasy, used in this work present viability peak at 09am. Stigmas remain receptive throughout the day of anthesis, allowing pollinations to be made throughout the day if pollen is viable. In JAB 20 hermaphrodite flowers, the applicatio... (Complete abstract click electronic access below) / Mestre
175

N-mixture models with auxiliary populations and for large population abundances

Parker, Matthew R. P. 29 April 2020 (has links)
The key results of this thesis are (1) an extension of N-mixture models to incorporate the additional layer of obfuscation brought by observing counts from a related auxiliary population (rather than the target population), (2) an extension of N-mixture models to allow for grouped counts, the purpose being two-fold: to extend the applicability of N-mixtures to larger population sizes, and to allow for the use of coarse counts in fitting N-mixture models, (3) a new R package allowing the easy application of the new N-mixture models, (4) a new R package allowing for optimization of multi-parameter functions using arbitrary precision arithmetic, which was a necessary tool for optimization of the likelihood in large population abundance N-mixture models, as well as (5) simulation studies validating the new grouped count models and comparing them to the classic N-mixtures models. / Graduate
176

Phylogeny of Five Taxa in the Felsenstein and Farris Zones

Lam, Eric Trung 18 March 2021 (has links)
Mathematical conditions which showed where parsimony was not consistent for four taxa were first introduced by Felsenstein in 1978. This was subsequently labelled the "Felsenstein zone". Following Felsenstein's findings, 'frequentists' conjectured that for five taxa there would also be a region in parameter space where parsimony is not consistent. In response, 'cladists' claimed that parsimony was consistent in a different region of parameter space, which is called the "Farris zone". However, no analytical description of the region in which this consistency occurs has been made. Furthermore, no mathematical extensions of this Felsenstein theory to five taxa or more has been made. The same is true for the Farris zone. In this thesis, we give a complete account for the Felsenstein zone and Farris zone for four and five taxa and interpret these in terms of the shape of the phylogenetic tree.
177

Mechanical behavior direct shear a volcanic sand reinforced with polypropylene fiber and cement

Maurizio, Cabrera Barrionuevo, Aguilar Jean Pierre, Dominguez, Lidia, Pacheco Miranda 30 September 2020 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This article describes consolidated Direct Cut tests not drained in the laboratory, carried out on samples of volcanic sand from Arequipa, Peru. The samples were tested for maximum dry density and optimal moisture content; Furthermore, they were reinforced with polypropylene fibers and cement. The samples were reinforced with 0.5% cement with respect to the dry weight of the sample soil and tested at 3 days. The added polypropylene fiber has dimensions of 48 mm wide with 1.2855 mm long and 0.3325 mm thick, and they were used in different percentages regarding the dry weight of the soil sample (0.25% -0.75% -1.00% -1.25%). The results of the tests indicated that the addition of polypropylene fibers together with the cement increases the resistance to cut proportionally to the amount of fiber up to 1% of fiber, this being the best result obtained, decreasing the resistance as the percentage of polypropylene fiber.
178

Relationship Between Isometric and Dynamic Strength in Recreationally Trained Men

McGuigan, Michael R., Newton, Michael J., Winchester, Jason B., Nelson, Arnold G. 01 September 2010 (has links)
The purpose of this investigation was to examine the relationships between measures ofmaximal isometric force (peak force [PF]), rate of force development (RFD), vertical jump performance (VJ) and 1-repetition maximum (1RM) strength in recreationally trained men. The subjects in this study were 26 men ([mean ± SD]: age 22± 1 years; height 175 ± 7 cm; mass 90 ± 10 kg). They were tested for PF using the isometric midthigh pull exercise. The 1RM for the squat and bench press exercise were determined as a measure of dynamic strength. Explosive strength was measured as RFD from the isometric force-time curve. Correlations between the variables were calculated using Pearson product moment correlation coefficient. There was a nearly perfect correlation between measures of PF and 1RM squat (r = 0.97, p < 0.05) and 1RM bench press (r = 0.99, p < 0.05). The correlations were very strong between VJ and PF (r = 0.72, p < 0.05) and 1RM bench press (r = 0.70, p < 0.05). There were also strong correlations between VJ and 1RM squat (r = 0.69, p < 0.05). There were no significant correlations with RFD. The results showed that isometric maximum strength determined during the isometric midthigh pull test correlated well with 1RM and VJ testing. However, RFD measured during the same test did not appear to correlate as well with other measures. The isometric midthigh pull provides an efficient method for assessing strength in recreationally trained individuals. Practioners wishing to obtain performance data related to maximum strength may wish to consider isometric testing as a less time intensive method of testing.
179

Minimum Genus and Maximum Planar Subgraph: Exact Algorithms and General Limits of Approximation Algorithms

Hedtke, Ivo 24 August 2017 (has links)
This thesis introduces exact (ILP- and SAT/PBS-based) algorithms for the Minimum Genus Problem and the Maximum Planar Subgraph Problem. It also considers general limits of approximation algorithms for the Maximum Planar Subgraph Problem.
180

A novel approach to forecast and manage electrical maximum demand

Amini, Amin 06 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Electric demand charge is a large portion (usually 40%) of electric bill in residential, commercial, and manufacturing sectors. This charge is based on the greatest of all demands that have occurred during a month recorded by utility provider for an end-user. During the past several years, electric demand forecasting have been broadly studied by utilities on account of the fact that it has a crucial impact on planning resources to provide consumers reliable power at all time; on the other hand, not many studies have been conducted on consumer side. In this thesis, a novel Maximum Daily Demand (MDD) forecasting method, called Adaptive-Rate-of-Change (ARC), is proposed by analysing real-time demand trend data and incorporating moving average calculations as well as rate of change formularization to develop a forecasting tool which can be applied on either utility or consumer sides. ARC algorithm is implemented on two different real case studies to develop very short-term load forecasting (VSTLF), short-term load forecasting (STLF), and medium-term load forecasting (MTLF). The Chi-square test is used to validate the forecasting results. The results of the test reveal that the ARC algorithm is 84% successful in forecasting maximum daily demands in a period of 72 days with the P-value equals to 0.0301. Demand charge is also estimated to be saved by $8,056 (345.6 kW) for the first year for case study I (a die casting company) by using ARC algorithm. Following that, a new Maximum Demand Management (MDM) method is proposed to provide electric consumers a complete package. The proposed MDM method broadens the electric consumer understanding of how MDD is sensitive to the temperature, production, occupancy, and different sub-systems. The MDM method are applied on two different real case studies to calculate sensitivities by using linear regression models. In all linear regression models, R-squareds calculated as 0.9037, 0.8987, and 0.8197 which indicate very good fits between fitted values and observed values. The results of proposed demand forecasting and management methods can be very helpful and beneficial in decision making for demand management and demand response program.

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