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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.
121

Espaçamentos ultra-adensado, adensado e convencional com densidade populacional variável em algodoeiro. / Ultra-narrow row, narrow row and conventional row with cotton variable density plant population.

Ariana Vieira Silva 17 January 2003 (has links)
No presente estudo foi avaliado a densidade populacional, por espaçamentos ultra-adensado, adensado e convencional entre fileiras e número de plantas por metro linear, através do crescimento, desenvolvimento e produtividade da cultivar de algodão IAC 23. O experimento foi conduzido na área experimental da ESALQ/USP, município de Piracicaba, Estado de São Paulo, no ano agrícola de 2001/02. O delineamento experimental foi o de blocos ao acaso em esquema fatorial, com 4 repetições, sendo três espaçamentos entre linhas (0,38, 0,76 e 0,95 m) e quatro densidades de plantas por metro linear (5, 8, 11 e 14). O controle da altura das plantas foi realizado através de regulador de crescimento. Em cada parcela experimental foram marcadas seis plantas ao acaso e analisados os seguintes parâmetros: estádios fenológicos, altura média das plantas, altura de inserção do 1º ramo frutífero, diâmetro do caule, número de ramos vegetativos e frutíferos, número de internódios e o número de capulhos por planta. Em duas plantas foram avaliados o índice de área foliar e a massa seca da parte aérea. Na área útil de cada parcela foi determinada a produção de algodão em caroço, a precocidade de colheita e em amostras de 20 capulhos por parcela foram realizadas as análises dos caracteres agronômicos de laboratório (massa média de uma capulho, massa de 100 sementes e porcentagem de fibra) e das características tecnológicas da fibra (comprimento da fibra, uniformidade de comprimento, tenacidade, micronaire e maturidade). Pelos resultados obtidos concluí-se que as condições ambientais foram favoráveis para o crescimento e desenvolvimento da cultivar IAC 23, completando o ciclo em 161 dias; quanto menor o espaçamento e maior a densidade de plantas na linha, maior o IAF durante o ciclo, menor o diâmetro do caule pelo estiolamento das plantas e menor o número de capuhos por planta; quanto maior o espaçamento e menor a densidade de plantas na linha, maior a massa seca da parte aérea e a altura média das plantas durante o ciclo; o índice de colheita é maior conforme o aumento do espaçamento enquanto que não altera com a densidade de plantas; maior densidade de plantas na linha eleva a altura de inserção do 1º ramo frutífero; independente do espaçamento e da densidade, o número de ramos vegetativos não é alterado enquanto que o número de ramos frutíferos e o número de internódios diminui com o aumento da população de plantas por área; a produção de algodão em caroço foi 12% e 8,4% superior nos espaçamentos ultra-adensado e adensado, respectivamente, comparado ao convencional; no espaçamento ultra-adensado na menor densidade de plantas na linha, a produção de algodão em caroço foi 29,2% e 22,3% superior, respectivamente, às produções dos espaçamentos adensado e convencional na mesma densidade de plantas na linha; a precocidade de colheita praticamente não é alterada na cultivar IAC 23, sobretudo com o aumento da população de plantas por área; os caracteres agronômicos de laboratório e as características tecnológicas da fibra não foram alteradas nas populações de plantas estudadas. / The purpose of this work was to study plant population density, by spacing between rows and plants per linear meter for the IAC 23 cotton cultivar under ultra-narrow row, narrow row or conventional row by analyzing plant growth, development and yield. The experiment was established in the experimental field of ESALQ/USP, Piracicaba, São Paulo, during the 2001/2002 season, in a randomized block design with four replications. Three rows (0,38, 0,76 and 0,95 m between lines) and four plant densities (5, 8, 11 and 14 plants per linear meter) were used. Plant height was controlled by growth regulator. Six plants per plot were labeled and analyzed for the phenological phase, average plant height, insertion height of the first fruit branch, stem diameter, number of vegetative and fruit branches, number of internodes and open bolls per plant. Two plants were analyzed per plot for the leaf area index (LAI) and plant top dry mass. Cotton yield and harvest early were determined considering the effective plot area. Samples of 20 open bolls randomized chosen per plot were analyzed for agronomical lab characteristics (average open boll mass, mass of 100 seeds and fiber percentage) and fiber technological characteristics (length, length uniformity, strength, micronaire and maturity). Results showed that the environmental conditions favored growth and development of the IAC 23 cultivar, which completed its lifecycle in 161 days; smaller row and higher plant density resulted in greater LAI, smaller stem diameter due to estiolation and fewer open bolls per plant; larger row and lower plant density promoted greater plant top dry mass and average plant height; the harvest index increased with row, although it was not altered by plant density; higher plant density in rows increased the insertion height of the first fruit branch; the number of vegetative branches was not influenced by plant row and density, while the number of fruit branches and internodes decreased with level of plant population per area; cotton yield was 12% and 8,4% higher for the ultra-narrow row and narrow row, respectively, when compared with the conventional row; cotton yield for the ultra-narrow row with the lowest plant density in rows was 29,2% and 22,3% higher than the yields for the narrow row and conventional row, respectively, considering the same plant density; harvest early of the IAC 23 cultivar varied with the increase in plant population per area; agronomical lab characteristics and fiber technological characteristics did not vary in the plant populations studied.
122

Desempenho agronômico de híbridos de milho em função de espaçamentos e densidades populacionais em três locais / Agronomic performance of maize hybrids according space and population densities in three locations

Gonçalves, Marcio Leandro 12 December 2008 (has links)
Made available in DSpace on 2017-07-10T17:37:27Z (GMT). No. of bitstreams: 1 Marcio Leandro Goncalves.pdf: 390674 bytes, checksum: e9135f2628f32cffc80e45f13f950692 (MD5) Previous issue date: 2008-12-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A study was conducted with the objetive to evaluate the effect of spacing between the plantation rows (0.45, 0.68 and 0.90 m) on plants population density of (50.000, 60.000, 70.000 and 80.000 plants ha-¹) about the grain productivity of three hibrid corn (Zea mays L.) A field experiment was conducted from September 10 to April 10/2008 in three different environments with different height, in Goioerê, Toledo and Cascavel localized in the west of Parana State. The design utilized was of randomized blocks into subdivided parcels. The spacing were placed in the main parcel and the population density and hybrids in sub parcels in a factorial schema. Biometric variables such as plant height, height of insertion of the first spike and diameter of stem and the components of production, number of rows, number of grains per spike, mass of grains per spike, the mass spike and productivity, were evaluated. Was no effect of row spacing, obtaining the maximum grain yield with the spacing of 0.57 m between rows, regardless of location. There was positive interaction between the environmental effect of plant population. The positive response to the increase of population in the Toledo plant was directly related to the level of soil fertility. In Cascavel Goioerê and no significant difference to the increase in population from 50,000 to 80,000 plants ha-1. In all locations the hybrid AS 1570 showed higher productivity of hybrid AS 1565 and AS 1575 / Com objetivo de avaliar o efeito do espaçamento entre linhas de plantio (0,45; 0,68 e 0,90 m), sob quatro densidades populacionais (50.000, 60.000, 70.000 e 80.000 plantas ha-1), sobre a produtividade de grãos de três híbridos de milho ( Zea mays L.) em três ambientes com diferentes altitudes, foram conduzidos experimentos de campo nos municípios de Goioerê, Toledo e Cascavel, ambos no estado do Paraná na região oeste no período de 10 de setembro de 2007 a 10 de abril de 2008. O delineamento utilizado foi de blocos ao acaso dispostos em parcelas subdivididas. Os espaçamentos foram alocados na parcela principal e as densidades populacionais e híbridos nas subparcelas no esquema fatorial. Foram avaliadas as variáveis biométricas: altura de planta, altura de inserção da primeira espiga e diâmetro de colmo e os componentes da produção: número de fileiras, número de grãos por espiga, massa de grãos por espiga, massa de espiga e produtividade. Houve efeito do espaçamento entre linhas, obtendo o máximo rendimento de grãos com o espaçamento de 0,57 m entre linhas, independente do local. Houve interação positiva entre ambientes ao efeito de população de plantas. A resposta positiva ao aumento de população de plantas de Toledo foi diretamente relacionado ao nível de fertilidade do solo. Em Goioerê e Cascavel não houve diferença significativa ao aumento de densidade populacional de 50.000 a 80.000 plantas ha-1. Em todos os locais o híbrido AS 1570 apresentou produtividade superior aos híbridos AS 1565 e AS 1575
123

Effects of Skewed Probe Distributions on Temporal Bisection in Rats: Factors in the Judgment of Ambiguous Intervals

January 2019 (has links)
abstract: Temporal bisection is a common procedure for the study of interval timing in humans and non-human animals, in which participants are trained to discriminate between a “short” and a “long” interval of time. Following stable and accurate discrimination, unreinforced probe intervals between the two values are tested. In temporal bisection studies, intermediate non-reinforced probe intervals are typically arithmetically- or geometrically- spaced, yielding point of subjective equality at the arithmetic and geometric mean of the trained anchor intervals. Brown et al. (2005) suggest that judgement of the length of an interval, even when not reinforced, is influenced by its subjective length in comparison to that of other intervals. This hypothesis predicts that skewing the distribution of probe intervals shifts the psychophysical function relating interval length to the probability of reporting that interval as “long.” Data from the present temporal bisection study, using rats, suggest that there may be a within-session shift in temporal bisection responding which accounts for observed shifts in the psychophysical functions, and that this may also influence how rats categorize ambiguous intervals. / Dissertation/Thesis / Masters Thesis Psychology 2019
124

Effect of delayed sowing and increased crop density on weed emergence and competition with wheat

Gaongalelwe, Motlhasedi Olebile. January 2002 (has links) (PDF)
"July 2002" Bibliography: leaves 40-46.
125

Effect of plant surface area on organic carbon removal in wetlands

Kuehn, Elaine Jinx 30 November 1994 (has links)
This study investigated the effect of plant surface area (plant density) on the efficiency of organic carbon removal in a bench-scale constructed wetland. Constructed wetlands are commonly assumed to be biofilm reactors in which organic carbon removal occurs primarily through sedimentation and aerobic degradation by attached microbial biofilms. In conventional biofilm reactors, aerobic degradation of organic carbon is proportional to the amount of surface area for microbial attachment, provided that sufficient oxygen is available. In contrast, current design equations for constructed wetlands assume that the amount of surface area is not an important parameter. A bench-scale simulation of a constructed wetland was conducted, using bulrushes planted at varying plant densities in soil with a free water surface depth of about 0.27 m. The carbon source was diluted ENSUR (TM). Total organic carbon (TOC) removal was measured. Concentration of TOC was correlated with biochemical oxygen demand (BOD). Tests were conducted in conditions of light and dark, and under two different carbon loadings. Performance of bulrushes was compared with that of inert acrylic rods. The rate of carbon removal by mature bulrushes was found to increase with increasing plant density until oxygen became depleted. Higher densities degraded carbon at rates much faster than those predicted by current design equations. Young bulrushes degraded carbon at faster rates than mature bulrushes. Once oxygen was depleted, rates of degradation were reduced to rates anticipated by current models. When plant density was 15% or greater, oxygen became depleted in less than 6 hours. Removal efficiency was greater at higher loadings (70 mg/l BOD) than at lower loadings (25 mg/l BOD). Bulrushes performed significantly better than inert rods, sometimes by a full order of magnitude. The microbial community on the bulrushes appeared to be more complex and robust than that on the rods. Also, the presence of light did not significantly increase degradation rates for the bulrushes but was significant for the rods. The microbial community on the rods contained a larger proportion of epiphytic algae. The presence of light did result is greater overall efficiency of removal for both bulrush and rods. Currently, a major drawback of constructed wetlands in wastewater treatment has been their demand for large areas of land. This study suggests that it would be possible to reduce the land area requirements for constructed wetlands for both carbon removal and nitrification/denitrification provided designs gave more consideration to oxygen supply. Using current designs, a retention time of 4-8 days typically results in 70% BOD removal. This experiment suggests that wetlands with a retention time of about 1 day could provide the same performance if additional oxygen were supplied. / Graduation date: 1995
126

微小重力下での直線液滴列に沿った火炎伝ぱ (第2報, 火炎伝ぱ速度特性)

梅村, 章, UMEMURA, Akira 08 1900 (has links)
No description available.
127

Optimizing Development Strategies to Increase Reserves in Unconventional Gas Reservoirs

Turkarslan, Gulcan 2010 August 1900 (has links)
The ever increasing energy demand brings about widespread interest to rapidly, profitably and efficiently develop unconventional resources, among which tight gas sands hold a significant portion. However, optimization of development strategies in tight gas fields is challenging, not only because of the wide range of depositional environments and large variability in reservoir properties, but also because the evaluation often has to deal with a multitude of wells, limited reservoir information, and time and budget constraints. Unfortunately, classical full-scale reservoir evaluation cannot be routinely employed by small- to medium-sized operators, given its timeconsuming and expensive nature. In addition, the full-scale evaluation is generally built on deterministic principles and produces a single realization of the reservoir, despite the significant uncertainty faced by operators. This work addresses the need for rapid and cost-efficient technologies to help operators determine optimal well spacing in highly uncertain and risky unconventional gas reservoirs. To achieve the research objectives, an integrated reservoir and decision modeling tool that fully incorporates uncertainty was developed. Monte Carlo simulation was used with a fast, approximate reservoir simulation model to match and predict production performance in unconventional gas reservoirs. Simulation results were then fit with decline curves to enable direct integration of the reservoir model into a Bayesian decision model. These integrated tools were applied to the tight gas assets of Unconventional Gas Resources Inc. in the Berland River area, Alberta, Canada.
128

Numerical Investigation Of Natural Convection From Vertical Plate Finned Heat Sinks

Cakar, Kamil Mert 01 June 2009 (has links) (PDF)
The steady-state natural convection from vertically placed rectangular fins is investigated numerically by means of a commercial CFD program called ICEPAK. The effects of geometric parameters of fin arrays on the performance of heat dissipation from fin arrays are examined. In order to simulate the different fin configurations and compare the results with literature, two experimental studies from literature are selected. Optimum fin spacing for both studies are found numerically and compared with experimental studies. The models are first verified by simulating natural convection on vertically placed flat plate and comparing the results with literature. After verification 30 different fin array configurations for the first experimental case study and 15 different fin array configurations for the second experimental case study from literature are analyzed. It is observed that the present results agree very well with the optimum fin spacing results of the experimental studies. It is also observed that the empirical correlations in the literature are conservative and the numerically obtained correlations predict higher heat transfer rates.
129

Behaviour Of Pile Groups Under Lateral Loads

Ercan, Anil 01 April 2010 (has links) (PDF)
To investigate the lateral load distribution of each pile in a pile group, the bending moment distribution along the pile and the lateral group displacements with respect to pile location in the group, pile spacing, pile diameter and soil stiffness three dimensional finite element analysis were performed on 4x4 pile groups in clay. Different Elatic Modulus values, pile spacings, pile diameters and lateral load levels used in this study. In the analysis PLAXIS 3D Foundation geotechnical finite element package was used. It is found that, lateral load distribution among the piles was mainly a function of row location in the group independent from pile spacing. For a given load the leading row piles carried the greatest load. However, the trailing row piles carried almost the same loads. For a given load, bending moment values of the leading row piles were greater than the trailing row piles. On the other hand, as the spacing increased group displacements and individual pile loads decreased under the same applied load. However, this behavior was seen more clearly in the first and the second row piles. For the third and the fourth row piles, pile spacing became a less significant factor affecting the load distribution. It is also found that, pile diameter and soil stiffness are not significant factors on lateral load distribution as row location and pile spacing.
130

Evaluation of a system for double cropping cotton following small grains

Thacker, Gary William January 1979 (has links)
No description available.

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