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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.
71

ESA based fiber optical humidity sensor

Chen, Qiao 13 December 2002 (has links)
Several techniques for measuring humidity are presented. The goal of the study is to use the electrostatic self-assembled monolayer synthesis process to fabricate a Fabry-Parot Cavity based optical fiber humidity sensor. The sensing scheme bases on the refractive index change with relative humidity of the film applied to the end of optical fiber. That is, the change in reflected optical power indicates certain humidity. To achieve this, some chemicals induce on specific coating materials were applied at the end of optical fiber. In this thesis, experimental results are given to prove that the humidity sensor has high sensitive and fast response time. Furthermore, we investigate the potential for the use of human breathing monitoring and air flow rate detection. Results from preliminary tests of each are given. / Master of Science
72

Examination of Drying and Psychrometric Properties of High Water-Cement Ratio Concretes

McNicol, Thomas James 22 March 2016 (has links)
Moisture from concrete has been estimated to be responsible for over $1 billion annually from damages in floor coverings. To prevent damages, flooring manufacturers require installers to test concrete moisture levels to determine if the concrete has dried sufficiently to receive flooring or covering. Two of the main tests used in the United States to determine concrete moisture levels are moisture vapor emissions rate (MVER) tests and relative humidity (RH) tests. Changes in ambient temperature can affect the results of both RH and MVER tests. The goal of this study was to investigate the effects of ambient temperature changes on the RH of concrete, and compare the sensitivity of RH measurements to the results of MVER tests at the same ambient temperature. The RH of concrete was measured at 20%, 40%, 60%, and 80% of depth in each sample and tracked over a period of 24 days to develop drying curves at each depth, and drying profiles of each sample. The changes in concrete RH due to a change in ambient temperature were predicted using the psychrometric process and a model developed during this study. Due to size constraints on the concrete samples, ASTM 1869 had to be altered during the MVER tests. Typical RH change in the concrete samples was under 4% RH after either an increase or decrease in an ambient temperature of 5.5°C (10°F). The psychrometric process predicted that the concrete RH would change between 20% - 40% RH after the ambient temperature changed by 5.5°C. Psychrometric properties were not able to full describe the behavior of air in concrete pores so a new model was created to better predict the change in concrete RH after a change in ambient temperature. The developed model was able to predict concrete RH change within 5% error over the range of tested temperatures. / Master of Science
73

Behavior of and Crop Injury Induced by Native and Exotic Stink Bugs in Mid-Atlantic Soybean

Owens, David Robert 06 June 2012 (has links)
Cage studies were performed to determine if the current thresholds for stink bugs in soybean (one bug per 0.3 row m) need to be adjusted based on current soybean production practices and species present. Several soybean development stages were infested by two native stink bug species for three weeks using small cages in a field of double crop soybean at sites in Virginia, Maryland, and Delaware during 2007-2009. Large field cages were infested by an introduced species for two weeks in 2010-2011. Results showed that Euschistus servus Say and Acrosternum hilare Say adults or nymphs did not cause different levels of injury to soybean seed quality or effects on yield. Both A. hilare and the introduced Halyomorpha halys Stål injured soybean seed in a similar fashion at threshold-level densities. Full flowering R2 stage soybean were least affected by stink bug feeding, and full pod and beginning seed R4-R5 stage soybean were slightly more sensitive to injury than R6 although not at the Maryland 2011 site. Several sites had increased seed injury and decreased yield at threshold density populations. Finally, visual observations of stink bug vertical distribution inside soybean canopies were taken several times per day and compared with ambient and within-canopy temperature and relative humidity. Results indicated that these conditions did not influence the percentage of stink bugs below the top 38 cm sweep net intercept zone. In both years of observations, between 15 and 20% of stink bugs were observed below the 38 cm sweep net zone. / Master of Science in Life Sciences
74

Role of relative humidity in concrete expansion due to alkali-silica reaction and delayed ettringite formation: relative humidity thresholds, measurement methods, and coatings to mitigate expansion

Rust, Charles Karissa 03 September 2009 (has links)
Premature concrete deterioration due to alkali-silica reaction (ASR) and delayed ettringite formation (DEF) is a significant problem all over the world. In cases where these mechanisms were not initially prevented, mitigation is critical to halt expansion and cracking. The main objectives of the research presented herein were to study the effect of ambient relative humidity (RH) on rates of concrete expansion, to determine RH thresholds below which expansion due to ASR and/or DEF may be suppressed, and to evaluate coatings intended to lower the internal RH of concrete and thus minimize future potential for damage. Results from testing showed that the RH threshold for ASR was below 82%, the RH threshold for DEF was below 92%, and the RH threshold for combined ASR and DEF could be about 83% for the materials tested. Furthermore, it was shown that some coatings are effective in reducing ASR- and DEF-related expansion by lowering the internal RH of concrete. / text
75

Influence of atmospheric moisture on the corrosion of chloride-contaminated wrought iron

Lewis, Mark R. T. January 2009 (has links)
No description available.
76

Characterization of Perphenazine and Scopolamine Aerosols Generated Using the Capillary Aerosol Generator

Li, Xihao 01 January 2006 (has links)
The characterization of perphenazine and scopolamine aerosols generated using the capillary aerosol generator (CAG) was reported. Variables including steady state power, the formulation vehicle, the drug concentration and the formulation flow rate were studied for their effects on the chemical stability and particle size of these drug aerosols.Stability-indicating HPLC and LC-MS assays were developed and validated for perphenazine and scopolamine, respectively. The chemical stability of each compound was investigated under a variety of stress conditions and the structure of degradation products was proposed.Perphenazine aerosols were generated from propylene glycol (PG) formulations with concentrations of 9, 48 and 90mM at formulation flow rates of 2.5 and 5.0µL/s at a series of steady state powers. At higher aerosolization powers, the low concentration formulation (9mM) degraded with dehalogenation being the major pathway. The size of perphenazine aerosols was between 0.4 to 0.6µm. Changing the solute concentration produced only small changes (~0.2µm) in perphenazine aerosol particle size. The formulation flow rate did not significantly affect the aerosol size.Scopolamine degraded significantly when aerosolized in PG formulations. It was possible to generate chemically stable scopolamine aerosols from ethanol formulations. Significant amounts of degradation products were formed only at or above 4.6W at 5.0µL/s. Hydrolysis and dehydration appeared to be the major degradation pathways at higher powers and low formulation flow rate. The MMAD of scopolamine aerosols was between 0.5 and 2.0µm from 8, 20 and 40mM formulations at 5.0 and 10.0µL/s. The size of scopolamine aerosols increased as a function of increasing the solute concentration. Increasing the formulation flow rate increased the linear velocity of the spray, thus the Reynolds number was increased and smaller particles were generated.
77

Interações entre a atmosfera e a superfície terrestre: variações da temperatura e umidade na bacia B do Núcleo Cunha (IF) - SP / Interactions between atmosphere and land surface: temperature and humidity variations in Basin B of Núcleo Cunha (IF) - SP

Armani, Gustavo 08 October 2004 (has links)
Os objetivos desta pesquisa são: a) compreender como a temperatura do ar e a umidade relativa na bacia B do Núcleo Cunha (IF) estão relacionadas aos controles climáticos (altitude, declividade e orientação das vertentes, vegetação, a configuração do céu, etc); b) entender qual a importância de cada controle climático nas variações de temperatura e umidade relativa sob a ação de diferentes sistemas atmosféricos. Os controles microclimáticos produzem alterações no ritmo da temperatura e da umidade relativa de diferentes formas e graus de importância em função do sistema atmosférico atuante. Entretanto, a combinação de controles climáticos específicos pode criar ambientes que mantém o ritmo da temperatura e umidade mais estável, independente do sistema atmosférico que estiver atuando. A água no solo desempenha um papel fundamental na minimização das variações da temperatura e da umidade em ambientes específicos. A vegetação também desempenha um papel importante no controle dos valores de umidade relativa, sendo mais relevante que a declividade e a orientação da vertente. As unidades climáticas da Bacia B foram delimitadas como síntese de todas as interações entre os atributos e controles climáticos. O conceito de unidade climática como um espaço onde a interação entre os atributos e controles climáticos tem uma certa homogeneidade, permitiu a delimitação de quatro topoclimas e muitas unidades microclimáticas na bacia B. / The objectives of this work are: a) to undestand how the air temperature and relative humidity in Basin B of Núcleo Cunha (IF) relate to micro and topoclimatic controls (altitude, gradient, slope orientation, vegetation, sky diagram, etc.); b) to comprehend the relative importance of each micro and topoclimatic control in the air temperature and relative humidity variation within different atmospheric systems. Micro and topoclimatic controls influence temperature and relative humidity variation differently in each atmospheric system. However, the arrangement of some specific climatic controls generates environments that conserve the rhythm of temperature and relative humidity, whatever the atmospheric system. Water in the soil has an evident role in the reduction of temperature and relative humidity variation. Vegetation has a fundamental role in the maintenance of the relative humidity, being clearly more importante than gradient and slope orientation. Climatic units of Basin B were delimited as a synsthesis of all interactions. The concept of climate units as a space where climatic attributes and controls keep a relative homogeneity, made possible the identification of four topoclimates and several microclimates units.
78

Mögel på Textil -vid import av textila varor / Mold growth in Textiles : during import of textile products

Svennered, Alexandra, Carlson, Jenny January 2012 (has links)
Under lagring och transport av textila varor från Asien kan risken för mögelangrepp vara stor, något som sedan vid uppackning kan vara skadligt för hälsan. Situationen så som det ser ut idag kan medföra stora problem och kostnader hos textilföretag och att hitta möjliga åtgärder för att förebygga skador är därför av stort intresse. För att kartlägga problemen med mögelangrepp på textila material har både informationssökning och praktiskt arbete genomförts. Mögeltillväxt sker då det är gynnsamma betingelser med hänsyn till klimat, näring och syretillgång. För att mögeltillväxt inte ska angripa textila varor finns en rad förebyggande åtgärder som kan vidtas, åtgärder som alla handlar om att göra förutsättningarna på ett eller annat sätt ogynnsamma. Olika textila material angrips olika lätt av mögel men genom att hålla varorna rena från smuts samt ha kontroll över den relativa fuktigheten kan varorna klara sig en längre tid utan att bli angripna. Reglering av den relativa fuktigheten kan göras genom användning av avfuktare eller diverse fuktabsorbenter. Även användning av biocider på varorna i samband med packning kan hämma mögeltillväxten. Textila materials benägenhet till att mögla beror på en rad faktorer och efter den mögelodling som satts igång kunde det konstateras att bomull är det material som lättast angrips. Vid uppackning av mögelskadade varor bör försiktighetsprincipen tillämpas och för att rädda de varor som angripits kan olika saneringsmetoder användas, där olika metoder lämpar sig för olika material. Dock har det visat sig, i studier som gjorts på byggmaterial, att vissa saneringsmetoder medfört en kvarvarande eller ökad toxinhalt efter sanering vilket således innebär att sanering inte alltid gör varorna brukbara. During storage and transport of textiles from Asia, the risk of mold growth is high. When unpacking the affected textiles the mold can be harmful to the health of the workers. Today, mold growth in textiles results in major problems and costs for the textile companies. Therefore, it is of great interest for the companies to find possible measures to prevent damages due to mold growth. In order to fully understand the problems with mold on the textiles, both a literature survey and practical work has been done. Mold growth occurs when there are favorable conditions with regard to climate, nutrients and oxygen. There are some preventative measures that can be taken to deter mold growth, which are all about making the conditions, in one way or another, unfavorable.The ease in which different textiles are attacked by mold varies greatly, but by keeping them clean and controlling the relative humidity, the textiles can last a long time without being attacked. The relative humidity can be controlled by using a dehumidifier or various moisture absorbers. Also, using biocides on fabrics during packing may inhibit mold growth. The propensity of mold growth on textiles depends on several factors. The mold experimentsrevealed that cotton is the most easily attacked material. When unpacking the mold damaged goods, the precautionary principle should be used and to save the textiles that have been attacked, different decontamination methods can be used. Different methods are useful for different materials. However, it has been found in studies of construction materials that some decontamination methods lead to residual or increased toxin levels after the decontamination. This means the decontamination does not always make the products usable. / Program: Textilingenjörsutbildningen
79

The role of moisture profiling towards understanding pharmaceutical solid state functionality : validation and the application of a moisture profiling analytical tool for investigation into the characterisation of, and prediction of, the effects of compaction and storage on different lactose physical forms

Seymour, Louise January 2015 (has links)
The majority of therapeutic pharmaceutical formulations are presented in the solid form. Moisture is able to play an important role in the functional performance of pharmaceutical solids. Moisture profiling is able to provide novel information with regards to the behaviour of moisture within materials using equilibrium relative humidity as a measurement. The hypothesis investigated explores the changes in equilibrium relative humidity of pharmaceutical material induced by physical, chemical or storage conditions, these are able to be monitored using the innovative moisture profiler system. The aims within this were to primarily validate the moisture profiler and secondly evaluate the effects of moisture on physical forms and with respect to effects of compaction, finally this was compared to conventional characterisation methods. Preliminary explorations were conducted in order to assess the validity of the moisture profiler, from this lactose was selected as a suitable pharmaceutical material for further work. Processing effects were then examined, firstly storage at elevated relative humidity of different forms of lactose were explored, and this was carried out with supplementary analysis. Secondly the effects of tabletting were explored, different compaction forces were investigated to observe if this had any notable effects on equilibrium relative humidity of the different lactose forms. Finally subsequent storage of the compacts were examined in order to explore if there were any changes in the equilibrium relative humidity.
80

Aspectos produtivos de fêmeas suínas e suas leitegadas em diferentes sistemas de ambiência na maternidade / Influence of different farrowing house cooling systems on the productivity of sows and their litters

Morales, Oscar Ernesto dos Santos January 2010 (has links)
A manutenção das matrizes suínas fora da zona de conforto térmico compromete o seu desempenho, em especial no período lactacional, devido a redução no consumo voluntário de ração e na produção de leite. O estresse por calor é um desafio devido a dificuldade da espécie em dissipar calor, tendo como principal alternativa o uso da respiração para perder calor em situações de alta temperatura. Alternativas estruturais, como ventilação, gotejamento, resfriamento de piso e uso de processo evaporativo adiabáticos servem para amenizar as perdas produtivas. O objetivo do estudo foi analisar a influência de três sistemas de ambiência utilizando as variáveis temperatura e umidade relativa do ar, sobre os aspectos produtivos de fêmeas suínas e suas leitegadas. Foram utilizadas 244 fêmeas, em três tratamentos e três repetições. Ambiente climatizado - AC (n= 79), temperatura da sala de maternidade controlada por um sistema de resfriamento evaporativo adiabático, associado à ventilação negativa; Ar sobre as fêmeas - ASF (n= 82), saída individual de ar refrigerado sobre as fêmeas associado ao manejo de cortinas; Manejo de cortinas - MC (n= 83). Nas matrizes foi avaliado; o peso, a espessura de toucinho (ET), o escore corporal visual (ECV) pós-parto e ao desmame, e o intervalo desmame-estro (IDE) e o consumo médio diário de ração (CMR) na lactação. Dos leitões foi registrado o peso na uniformização, aos 14 dias e ao desmame. As mínimas e máximas diárias das variáveis temperatura e umidade relativa do ar (UR) foram mensuradas, bem como calculados as médias destas. As variáveis foram analisadas pelo procedimento GLM. As médias foram comparadas pelo teste de Tukey-Kramer, com nível de 5% de significância. A temperatura média observada no tratamento AC (23,0ºC) foi inferior e a UR (88,5%) superior quando comparada as dos demais. Para o CMR foi observada uma interação significativa entre os tratamentos e as repetições avaliadas. Na primeira repetição, o CMR foi maior no AC do que no MC. Na segunda repetição, não houve diferença entre os sistemas e, na terceira, os três sistemas diferiram entre si, com o maior CMR sendo observado no AC e o menor no MC. Apesar disso não foram observadas diferenças com relação a perda de peso lactacional e IDE. No entanto, o peso dos leitões ao desmame no AC (6164,2 g) foi semelhante aos demais, enquanto no ASF (6205,5 g) foi superior ao MC (5970,2 g). O tratamento ambiente climatizado foi efetivo em diminuir a temperatura ambiente, sendo uma alternativa para prover conforto térmico às fêmeas lactantes. No tratamento AC, o consumo de ração pelas fêmeas foi maior em uma das repetições, mas os leitões dos tratamentos AC e ASF tiveram desempenho semelhante e o primeiro não diferiu do MC, provavelmente por terem mobilizado mais energia para a manutenção da temperatura. / Maintaining sows outside the zone of thermal comfort compromises their performance, especially during lactation, mainly due to reductions in voluntary feed intake and milk production. The heat stress is a challenge because of the difficulty of the sow to dissipate heat with the main alternative use of breathing to lose heat in situations of high temperature. Structural alternatives, such as ventilation, drip, cooling and floor using adiabatic evaporative cooling to mitigate losses arising productive. This study analyzes the influence of three different cooling systems on the productivity of sows and their litters using the variables temperature and relative humidity. Two hundred and forty-four females were divided into three treatment and three replication groups: air-conditioned - AC (n = 79), with farrowing house temperature controlled by a system of adiabatic evaporative cooling combined with negative ventilation; snout cooler - SC (n = 82), with a cold air outlet directed towards females, combined with management of curtains; and management of curtains - MC (n = 83). The following variables were assessed for all sows: weight, backfat thickness (BFT), and visual body condition score (BCS), postpartum and at weaning, as well as weaning-to-estrus interval (WEI) and average daily feed intake (ADFI) during lactation. Piglet weight was recorded at cross-fostering, after 14 days, and at weaning. Minimum and maximum daily temperatures and relative humidity (RH) were measured and averaged. Variables were analyzed using the GLM procedure and means were compared using the Tukey-Kramer test at the 5% level of significance. Lower temperature averages were found for the AC treatment (23.0°C) and higher for RH (88.5%) than for others. There was significant interaction between treatment and evaluation periods for ADFI. In the first period, ADFI was higher in the AC group than in the MC one. In the second, there was no difference between the systems, while the three systems differed significantly in the third, with the largest ADFI found in AC and the lowest in MC. Yet there were no differences with respect to lactation weight loss and WEI. However, piglet weight at weaning in the AC group (6164.2g) was lower than in the SC (6205.5g) and higher than in the MC (5970.2g). The air-conditioned room treatment was effective in decreasing the temperature, and an alternative to provide thermal comfort to the lactating. In the air-conditioned room treatment, feed intake by females was higher in the replications, but the piglets from treatments air-conditioned room and snout cooler were similar and not different from the first management of curtains, probably because they had mobilized more energy to maintain temperature.

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