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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.
51

WET'o stebejimų redukcijos tobulinimas: atmosferinė ekstinkcija / WET observation reduction perfection: atmospherical extinction

Ramaška, Egidijus 16 June 2006 (has links)
This job point was make a computer program, by Pakstiene (Lithuania) and Solheim (Norway) method. Only by WET observed you could set comperable stars spectral classes, when are known programmable stars spectral class, and score extinction.
52

Some studies of laser Doppler anemometry in wet steam

Foster, Stephen John January 1985 (has links)
This study concerns the use of counter based laser Doppler anemometry in a wet steam flow of variable wetness fraction. Velocity measurements across the flow were made under different steam conditions. Comparison was made with a theoretical profile based upon a simple flow analysis. A small radial turbocharger was used as a means of extracting enthalpy homogeneously from a dry superheated flow of steam using the compressor as a brake. The wetness fraction of the exhaust was estimated using measured values of the thermodynamic properties. A laser extinction method was used to determine the number concentration and mean radius of the water droplets acting as natural scatterers in the wet steam. A laser anemometer was designed which made use of the properties of a propagating gaussian beam to produce a small probe volume. This was required to reduce the number of water droplets likely to be present simultaneously in the measuring volume. Good Doppler signals were obtained and these have been presented for a range of wet steam conditions. A computer model was developed to predict the scattering of laser light through wet steam. Results have shown that this can be accurately modelled using a particle size distribution function. The program written to perform the simulation takes into account both single and multiple scattering events. The parameters used for the distribution function required a knowledge of the wetness fraction and so provided a useful means of checking the estimate based upon the thermodynamic measurements. It has been demonstrated that the ability to obtain Doppler signals from the wet steam can be predicted by computation of the signal-to-noise ratio for the medium. Good results were obtained for the wet steam conditions under investigation.
53

Self-polymerized Dopamine Thin Film as Bioadhesive

Yang, Fut January 2012 (has links)
Dopamine is an interesting biomolecule that functions as a neurotransmitter in the brain. It has been found able to stick to almost all surfaces due to its unique catecholamine structure. Under alkaline conditions, the catechol functional group oxidizes to quinone allowing dopamine to self-polymerize and form thin films on support surfaces. The facts that dopamine can be coated to virtually any materials and the amine and catechol functional groups support a variety of reactions with organic species make polydopamine an attractive multifunctional bioadhesive/coating. To date, most of research on polydopamine has been focusing on its applications as thin films and little attention has been paid to the adhesion aspect of the material. In the study, we evaluated the properties of self-polymerized dopamine thin films as a bioadhesive. The thesis consists of three consecutive studies: (i) characterization of the adhesion properties of polydopamine thin films; (ii) investigation of the mechanical properties of polydopamine thin films; and (iii) exploration of the potential of polydopamine thin films as a wet adhesive. Fundamental insights on the wettability, adhesion behaviours, and mechanical properties of polydopamine thin films for both wet and dry conditions were derived through sets of well-designed contact angle, contact adhesion, and contact deformation experiments. It was found that dopamine is able to coat plastic, ceramic and metal surfaces, and join or bond rigid substrates but might not be suitable for joining soft or flexible parts as polydopamine is fairly rigid and the bonding might be too slow and too rigid for practical applications if polydopamine is directly used as an adhesive. Based on the understanding, a new strategy for fabricating underwater adhesive was proposed and tested. In the strategy, polydopamine with ferric ion as the oxidant was utilized as a cross-linker to alginate solution, effectively turning the solution into a wet adhesive, which demonstrated better practical performances than other studies; the adhesive was able to produce a permanent tensile adhesive strength of 80 kPa joining aluminum and glass with macroscopic roughness at the interface within 2 hours of curing time. Inspired by the results from the contact deformation experiments, we were able to extend the JKR theory with the well-known plate theory to accommodate the deformation of nanometer thin films, obtaining their elasticity. We termed this extended theory the “thin film contact mechanics” and validated the theory against gold thin films and found it predicted the mechanical behaviours of the thin films fairly well.
54

Soil and vegetation characteristics of montane and subalpine wet meadows, Sierra Nevada, California

Olsen, Hayley R. January 2009 (has links)
Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on June 16, 2010). Includes bibliographical references.
55

De Algemene wet bestuursrecht en het maken van bezwaar zwaartepunten van een bestuurlijke voorprocedure /

Notten, Joseph Hubertus Winand. January 1998 (has links)
Proefschrift Universiteit Maastricht. / Met lit. opg., reg. - Met samenvatting in het Engels.
56

Développement de nouveaux agents de tannage durables / Development of sustainable tanning agents

Rabodon, Ghislain 18 December 2018 (has links)
Le procédé d'obtention du cuir à partir de peaux est appelé tannage. Il agit par stabilisation chimique du collagène. Il permet de transformer la peau en un matériau stable et durable. Actuellement, plus de 90% de la production mondiale de cuir est effectuée avec du sulfate de chrome, et les effluents du tannage contiennent des quantités importantes de ce sel métallique qu'il faut impérativement traiter par des procédés couteux. L’objectif de ce projet est de proposer une alternative, durable et écologique, au chrome pour le tannage. Dans ce but, des composés organiques ont été synthétisés et leur capacité à stabiliser le collagène a été évaluée par différentes méthodes. Des essais à petite échelle ont été réalisés sur du collagène pur et la capacité de stabilisation du collagène par ces composés organiques a été évaluée par DSC. Les composés organiques sélectionnés suite à ces essais ont été testés sur des peaux entières en tannerie. / The manufacturing process used to obtain leather from skin is called tanning. It acts by chemical stabilization of collagen, which transforms the skin into a stable and durable material. Currently, more than 90% of the production of leather worldwide is carried out with chromium sulfate. Therefore, tanning effluents produce significant quantities of this metal salt, which must be treated by expensive processes. The purpose of this project is to offer a sustainable alternative to chromium for tanning. To this end, organic compounds have been synthesized and their ability to stabilize collagen has been evaluated by different methods. Small-scale tests were carried out on collagen and its stabilization by these organic compounds was evaluated by DSC. The organic compounds selected after these tests were then tested on hides.
57

CHARACTERIZATION AND CONTROL OF ODOR EMISSIONS FROM CONCENTRATED ANIMAL FEEDING OPERATIONS

LAMICHHANE, PRABHAT 02 October 2006 (has links)
No description available.
58

The ecology of the Lough Neagh woodlands

Butler, Christine January 1996 (has links)
No description available.
59

Mild Wet Torrefaction and Characterization of Woody Biomass from Mozambique for Thermal Applications

Cuvilas, Carlos Alberto January 2015 (has links)
Mozambique has vast forestry resources and also considerable biomass waste material such as bagasse, rice husks, sawdust, coconut husks and shells, cashew nut shell and lump charcoal waste. The potential of the total residues from the agricultural sector and the forest industry is estimated to be approximately 13 PJ. This amount of energy covers totally the production of charcoal which amounted to approximately 12.7 PJ in 2006. Although biomass is an attractive renewable source of energy, it is generally difficult to handle, transport, storage and use due to its lower homogeneity, its lower energy density and the presence of non-combustible inorganic constituents, which leads to different problems in energy conversion units such as deposition, sintering, agglomeration, fouling and corrosion. Therefore, a pretreatment of the biomass to solve these problems could lead to a change of current biomass utilization situation. The aim of this study is to convert Mozambican woody biomass residue into a solid biochar that resembles low-grade coal. In this work the current energy situation in Mozambique has been reviewed, and the available and potential renewable sources including residues from agricultural crops and forest industry as energy have been assessed. It was found that the country is endowed with great potential for biofuel, solar, hydro and wind energy production. However, the production today is still far from fulfilling the energy needs of the country, and the majority of people are still not benefiting from these resources. Charcoal and firewood are still the main sources of energy and will continue to play a very important role in the near future. Additionally, enormous amounts of energy resources are wasted, especially in the agricultural sector. These residues are not visible on national energy statistics. The chemical composition and the fuelwood value index (FVI) showed that by failing to efficiently utilise residues from Afzelia quanzensis, Millettia stuhlmannii and Pterocarpus angolensis, an opportunity to reduce some of the energy related problems is missed. An evaluation of effect of a mild wet torrefaction pretreatment showed that the chemical composition of the biochar is substantially different than the feedstock. The use of diluted acid as catalysts improves the biochar quality, namely in terms of the energy density and ash characteristics; however, the increment of the S content in the final product should be considered for market acceptance (because the fuels have a maximum allowance for S concentration). The thermal behaviour of the untreated and treated biomass was also investigated. The pyrolytic products of umbila and spruce were affected by the treatment and catalyst in terms of yield and composition of the vapours. / <p>QC 20150202</p>
60

Quantification of atmospheric water soluble inorganic and organic nitrogen

Benítez, Juan Manuel González January 2010 (has links)
The key aims of this project were: (i) investigation of atmospheric nitrogen deposition, focused on discrimination between bulk, wet and dry deposition, and between particulate matter and gas phase, (ii) accurate quantification of the contributions of dissolved organic and inorganic nitrogen to each type of deposition, and (iii) exploration of the origin and potential sources of atmospheric water soluble organic nitrogen (WSON). This project was particularly focused on the WSON fraction because, despite it being a potentially important source of bioavailable reactive nitrogen, a number of questions regarding its deposition mechanism (wet vs. dry), composition and origin (natural, anthropogenic or mixed) remain unanswered. There are two major difficulties in WSON determination: (i) the diversity of organic nitrogen compounds compared with the inorganic forms, and (ii) the lack of a direct determination method: the derivation of organic nitrogen concentrations in an aqueous sample involves the determination of the dissolved inorganic nitrogen (DIN) species concentration, comprising nitrate and ammonium, the determination of the total dissolved nitrogen (TDN) concentration, and the subtraction of the DIN concentrations from the TDN concentration. TDN determination requires a preparatory digestion step: high-temperature catalytic oxidation was the method used in this study. Ion chromatography (IC) was the method of choice for nitrate determination, whilst ammonium determination was by IC for rain samples, and by flow injection analysis for air samples collected into aqueous media. This thesis is structured in 3 main parts: the first part examines weekly rain data over a period of 22 months from June 2005 to March 2007 collected in 2 types of rain collector (bulk deposition and “dry+wet” deposition) located in a semi-rural area 15 km southwest of Edinburgh, UK (N55°51′44″, W3°12′19″). Bulk deposition collectors were the standard rain gauges used in the UK national network for monitoring precipitation composition. “Dry+wet” deposition collectors were flushing rain gauges equipped with a rain detector, a spray nozzle, a 2-way valve and two independent bottles to collect funnel washings (dry deposition) and true wet deposition. A key objective in this part of the work was the accurate quantification of inorganic and organic water-soluble nitrogen species contribution to each type of deposition. On average, for the 27 weekly samples with 3 valid replicates for the 2 types of collectors, DON represented 23% of the TDN in bulk deposition. Dry deposition of particles and gas on the funnel surface, rather than rain, contributed over half of all N-containing species (inorganic and organic). Some discrepancies were found between bulk and flushing rain gauges, for deposition of both TDN and DON, suggesting biological conversion and loss of inorganic N in the flushing samplers. The second stage of this project was the investigation of in situ atmospheric concentrations of WSN species, both organic and inorganic. Simultaneous daily measurements of ammonium, nitrate and WSON were made between July and November 2008 at the same semi-rural site in south-east Scotland. Discrimination between material from the gas and particle phases was achieved by means of Cofer scrubbers and PTFE membrane filters, respectively. Average concentrations of NH3 (determined as NH4+), NO2/HNO3 (determined as NO3-) and WSON in the gas phase were 82 ± 54 nmol N m-3, 2.6 ± 2.5 nmol N m-3 and 18 ± 12 nmol N m-3 respectively, and in the particle phase were 20 ± 24 nmol N m-3, 10 ± 9 nmol N m-3 and 8 ± 7 nmol N m-3 respectively (± represent standard deviation across all valid daily samples, not error of triplicate samples). Except for oxidised inorganic N, average concentrations in the gas phase were larger than in the particle phase. No evidence of solely agricultural or solely combustion sources of WSON was found, as no correlation in either phase between WSON and either NH4+ or NO3- could be established. The final stage of this project was to gain a broader picture of nitrogen deposition across Europe. Rain samples were analysed for TDN and DIN from a network of 21 different sampling locations, from the south of Portugal to the north of Finland. The average DON contribution across the 21 sampling sites was ~ 19% and, according to the data gathered in this study, DON species appeared largely unrelated specifically to agricultural or to combustion nitrogen sources, although the results varied widely from site to site. Overall, this work has shown that ON and its deposition comprises a significant component of total atmospheric reactive nitrogen.

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