- 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.
Search results
Showing 121 to 125 of 125 (0.037 seconds)Spelling suggestions: "subject:"[een] SULFURIC ACID"" "subject:"[enn] SULFURIC ACID""
| 121 |
Studium vývoje fázového složení v silikátových systémech dostupnými metodami a jejich optimalizace / Development of phase composition in silicate systems by available methods and their optimalizationOpravilová, Lenka January 2015 (has links)
One of the most prominent measurable parameters of the development of phases and phase transformations in inorganic systems are undoubtedly the volume changes of silicate matrix. The study of volume changes is crucial in the terms of usable durability of final product. They represent shrinkage or expansion of the material and may lead to significant decrease of technological and ecological parameters and often to complete destruction of these materials. Most often the volume changes can be observed when cement is used as a binder and in concretes, mortars, artificial aggregates and other similar materials. There are many methods to detect, define and determine the volume changes qualitatively or quantitatively. The development of phases was investigated as a part of the dissertation thesis and hence the volume changes were observed under the conditions closest to the real state in the construction industry. The raw materials and admixtures were selected which model the content of hazardous components present in conventional materials (both natural and secondary), used in construction and the relationship with volume changes was searched and demonstrated. The contacts for measuring the volume changes were attached to test surfaces of specimens and the physical - mechanical tests (volume changes, phase changes, strength, etc.), chemical analysis and ecotoxicity tests depending on the length of hydration were performed.
|
| 122 |
Исследование комбинированной технологии переработки медно-цинковых промпродуктов : магистерская диссертация / Study of the combined technologies of processing of copper-zinc middlingsБерстенев, Н. В., Berstenev, N. V. January 2016 (has links)
В представленной работе на тему «Исследование комбинированной технологии переработки медно-цинковых промпродуктов» произведены теоретические и лабораторные исследования по определению оптимальной технологии переработки медно-цинковых сульфидных промпродуктов гидрометаллургическим способом. Рассмотрены две эффективные технологии, проведено сравнение по объективным показателям, сделаны экологоэкономический и экономический расчеты. / In this study, entitled "Study of the combined technologies of processing of copper-zinc middlings" produced theoretical and laboratory studies to determine the best technology processing of copper-zinc sulphide middlings hydro- metallurgical method. Two efficient technologies are considered, compared to objective indicators, are made of ecological, and economic calculations.
|
| 123 |
Simulation Monte-Carlo de la radiolyse du dosimètre de Fricke par des neutrons rapides / Monte-Carlo simulation of fast neutron radiolysis in the Fricke dosimeterTippayamontri, Thititip January 2009 (has links)
Monte-Carlo calculations are used to simulate the stochastic effects of fast neutron-induced chemical changes in the radiolysis of the ferrous sulfate (Fricke) dosimeter. To study the dependence of the yield of ferric ions, G(Fe[superscript 3+]), on fast neutron energy, we have simulated, at 25 [degree centigrade], the oxidation of ferrous ions in aerated aqueous 0.4 M H[subscript 2]SO[subscript 4] (pH 0.46) solutions when subjected to ~0.5-10 MeV incident neutrons, as a function of time up to ~50 s. The radiation effects due to fast neutrons are estimated on the basis of track segment (or"escape") yields calculated for the first four recoil protons with appropriate weighting according to the energy deposited by each of these protons. For example, a 0.8-MeV neutron generates recoil protons of 0.505, 0.186, 0.069, and 0.025 MeV, with linear energy transfer (LET) values of ~41, 69, 82, and 62 keV/[micro]m, respectively. In doing so, we consider that further recoils make only a negligible contribution to radiation processes. Our results show that the radiolysis of dilute aqueous solutions by fast neutrons produces smaller radical yields and larger molecular yields (relative to the corresponding yields for the radiolysis of water by [superscript 60]Co [gamma]-rays or fast electrons) due to the high LET associated to fast neutrons. The effect of recoil ions of oxygen, which is also taken into account in the calculations, is shown to decrease G(Fe[superscript 3+]) by about 10%. Our calculated values of G(Fe[superscript 3+]) are found to increase slightly with increasing neutron energy over the energy range covered in this study, in good agreement with available experimental data. We have also simulated the effect of temperature on the G(Fe[superscript 3+]) values in the fast neutron radiolysis of the Fricke dosimeter from 25 to 300 [degree centigrade]. Our results show an increase of G(Fe[superscript 3+]) with increasing temperature, which is readily explained by an increase in the yields of free radicals and a decrease in those of molecular products. For 0.8-MeV incident neutrons (the only case for which experimental data are available in the literature), there is a ~23% increase in G(Fe[superscript 3+]) on going from 25 to 300 [degree centigrade]. Although these results are in reasonable agreement with experiment, more experimental data, in particular for different incident neutron energies, would be needed to test more rigorously our Fe[superscript 3+] ion yield results at elevated temperatures.
|
| 124 |
Sulfuric Acid: Its Potential for Improving Irrigation Water QualityBohn, H. L., Westerman, R. L. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The 2 major environmental problems of Arizona and the southwest are the alkalinization of soil and water by irrigation and air pollution from copper smelting. It is proposed that the amelioration of both problems may be solved through a common process. This is the production of sulfuric acid from sulfur dioxide, which is the main pollutant of smelter effluent gases. The conversion process is cheap and easy, and the sulfuric acid could then be added to irrigation waters to increase the solubility of CA carbonate in the soil, thereby decreasing alkalinity. Lower alkalinity results in increased soil permeability and increased water use efficiency by plants. The potential market for sulfuric acid in irrigation was calculated, on the basis of neutralizing 90% of the bicarbonate ion concentration in Colorado River water and Arizona well water, to be about 1.6 million tons annually, representing about 1/3 of the sulfur now dissipated by smelters as air pollution. This market includes both the Imperial Valley of California and the Mexicali Valley of Mexico, both of which are currently experiencing mounting salinity problems. Salinity itself is not amenable to this treatment, but the cumulative increase in NA and bicarbonate may be slowed and reversed, leading to gradual soil stabilization.
|
| 125 |
Partikelbildung bei der Alkenozonolyse und ihre Kopplung an die Radikalchemie / Particle formation during the ozonolysis of alkenes and its interconnection with radical chemistryKeunecke, Claudia 11 May 2012 (has links)
No description available.
|
Page generated in 0.0675 seconds