Thematische Bibliographien / Calcined dolomite

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Auswahl der wissenschaftlichen Literatur zum Thema „Calcined dolomite“

Autor: Grafiati

Veröffentlicht am 28. Juni 2021

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Zeitschriftenartikel zum Thema "Calcined dolomite"

Mohammed, M. A. A., A. Salmiaton, W. A. K. G. Wan Azlina, M. S. Mohamad Amran und Y. H. Taufiq-Yap. „Preparation and Characterization of Malaysian Dolomites as a Tar Cracking Catalyst in Biomass Gasification Process“. Journal of Energy 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/791582.

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Three types of local Malaysian dolomites were characterized to investigate their suitability for use as tar-cracking catalysts in the biomass gasification process. The dolomites were calcined to examine the effect of the calcination process on dolomite’s catalytic activity and properties. The modifications undergone by dolomites consequent to thermal treatment were investigated using various analytical methods. Thermogravimetric and differential thermal analyses indicated that the dolomites underwent two stages of decomposition during the calcination process. The X-ray diffraction and Fourier-transform infrared spectra analyses showed that thermal treatment of dolomite played a significant role in the disappearance of the CaMg(CO3)2phase, producing the MgO-CaO form of dolomite. The scanning electron microscopy microphotographs of dolomite indicated that the morphological properties were profoundly affected by the calcination process, which led to the formation of a highly porous surface with small spherical particles. In addition, the calcination of dolomite led to the elimination of carbon dioxide and increases in the values of the specific surface area and average pore diameter, as indicated by surface area analysis. The results showed that calcined Malaysian dolomites have great potential to be applied as tar-cracking catalysts in the biomass gasification process based on their favorable physical properties.

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Wang, Fei, Toshihiro Kuzuya, Shinji Hirai, Jihua Li und Te Li. „Carbon Dioxide Absorption and Release Properties of Pyrolysis Products of Dolomite Calcined in Vacuum Atmosphere“. Scientific World Journal 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/862762.

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The decomposition of dolomite into CaO and MgO was performed at 1073 K in vacuum and at 1273 K in an Ar atmosphere. The dolomite calcined in vacuum was found to have a higher specific surface area and a higher micropore volume when compared to the dolomite calcined in the Ar atmosphere. These pyrolysis products of dolomite were reacted with CO2at 673 K for 21.6 ks. On the absorption of CO2, the formation of CaCO3was observed. The degree of absorption of the dolomite calcined in vacuum was determined to be above 50%, which was higher than the degree of absorption of the dolomite calcined in the Ar atmosphere. The CO2absorption and release procedures were repeated three times for the dolomite calcined in vacuum. The specific surface area and micropore volume of calcined dolomite decreased with successive repetitions of the CO2absorption and release cycles leading to a decrease in the degree of absorption of CO2.

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Hartman, M., O. Trnka und K. Svoboda. „Fluidization characteristics of dolomite and calcined dolomite particles“. Chemical Engineering Science 55, Nr. 24 (Dezember 2000): 6269–74. http://dx.doi.org/10.1016/s0009-2509(00)00409-7.

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Ñústez Castaño, Stephanie Alexa, Duvan Oswaldo Villamizar Castro und Edgar Mauricio Vargas Solano. „Evaluation of dolomite as catalyst in the transesterification reaction using palm oil (RBD)“. DYNA 86, Nr. 209 (01.04.2019): 180–87. http://dx.doi.org/10.15446/dyna.v86n209.74126.

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In this study, the catalytic activity of dolomite was evaluated for the transesterification of Colombian RBD palm oil with methanol, carried out in a batch reactor at 333,15K and 600rpm. The activated dolomites (calcined at 1073.15K for 2h) were characterized by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Hammett indicators method, and quantification of the surface area, average pore size and average pore volume BET. The influence of reaction variables such as catalyst amount (%wt /wt) and methanol / palm oil molar ratio (mole/mole) was investigated. Under the suitable reaction conditions, the amount of calcined dolomite equal to 4% (wt /wt) based on the weight of oil, the methanol-oil molar ratio equal to 9:1, and the reaction time = 1h, the methyl ester content of 82.67% of fatty acid methyl esters (FAME) can be achieved.

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Li, Ying Jie, Xin Xie, Chang Tian Liu und Sheng Li Niu. „Cyclic Carbonation Properties of CMA as CO₂ Sorbent at High Temperatures“. Advanced Materials Research 518-523 (Mai 2012): 655–58. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.655.

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Calcium-based minerals cyclic calcination/carbonation reaction is an effective approach to CO2 capture for coal-fired power plants. It was proposed that dolomite modified with acetic acid solution, i.e. calcium magnesium acetate (CMA), acted as a new CO2 sorbent for calcination/carbonation cycles. The carbonation conversions for CMA and dolomite with the number of cycles were experimentally investigated. The cyclic conversion for CMA is much greater than that for dolomite for the carbonation at 650-700 °C. The carbonation conversion for CMA achieves as high as 0.6 after 20 cycles. CMA maintains the great conversion for calcination at 1100 °C. CMA had a better anti-sintering than dolomite. The pore volume and pore area distributions for calcined CMA are superior to those for calcined dolomite.

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Vijan, Cristina Andreea, Alina Badanoiu, Georgeta Voicu und Adrian Ionut Nicoara. „Phosphate Cements Based on Calcined Dolomite: Influence of Calcination Temperature and Silica Addition“. Materials 14, Nr. 14 (09.07.2021): 3838. http://dx.doi.org/10.3390/ma14143838.

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The aim of this study is to assess the possibility of obtaining phosphate cements based on dolomite calcined at various temperatures with/without quartz sand addition. A lower calcination temperature of dolomite (1200 °C) determines a high increase in the system temperature when calcined dolomite is mixed with KH2PO4 (MKP) solution and also a rapid expansion of the paste. The increase in calcination temperature up to 1400 °C reduces the oxides reactivity; however, for lower dosages of MKP, the expansion phenomenon is still recorded. The increase in MKP dosage increases the compressive strength due to the formation of K-struvite. The mixing of dolomite with sand, followed by thermal treatment at 1200 °C, modifies its composition and reactivity; the compressive strength of phosphate cements obtained by mixing this solid precursor with MKP increases up to 28 days of curing. We assessed the nature of hydrates formed in the phosphate systems studied by X-ray diffraction in order to explain the hardening processes and the mechanical properties of these systems. The microstructure and elemental composition of hardened cement pastes were assessed by scanning electronic microscopy with energy-dispersive spectroscopy. The phosphate cements based on calcined magnesite or dolomite were used to immobilize an industrial hazardous waste with high chromium content. The partial substitution of calcined magnesite/dolomite with this waste determines an important decrease in compressive strengths. Nevertheless, the leaching tests confirm an adequate immobilization of chromium in some of the matrices studied (for a waste dosage corresponding to 0.5 wt % Cr).

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Baslayici, S., M. Bugdayci, A. Turan, L. Oncel und E. Acma. „Flue Gas Desulfurization by Using Calcined Dolomite“. IOP Conference Series: Materials Science and Engineering 614 (24.09.2019): 012015. http://dx.doi.org/10.1088/1757-899x/614/1/012015.

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Sasaki, Keiko, Mari Yoshida, Bashir Ahmmad, Naoyuki Fukumoto und Tsuyoshi Hirajima. „Sorption of fluoride on partially calcined dolomite“. Colloids and Surfaces A: Physicochemical and Engineering Aspects 435 (Oktober 2013): 56–62. http://dx.doi.org/10.1016/j.colsurfa.2012.11.039.

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Lopez-Ortiz, A., V. Collins-Martinez und D. P. Harrison. „SER Process Variable Evaluation for the Production of Hydrogen using Calcined Dolomite“. Journal of New Materials for Electrochemical Systems 14, Nr. 2 (07.04.2011): 121–26. http://dx.doi.org/10.14447/jnmes.v14i2.120.

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Reaction performance of the sorption enhanced reforming (SER) process for the production of hydrogen was studied using commercial dolomite as inexpensive solid CO2 absorbent. The combined reforming, shift, and CO2 separation reactions were studied using a laboratory-scale fixed-bed reactor as a function of temperature, feed gas composition, dolomite type, and dolomite and catalyst particle sizes. Reactor was loaded with a mixture of calcined dolomite (≈ 23g) and a commercial reforming catalyst (NiO/Al2O3, ≈ 10g). Temperature was varied from 550 to 650°C at 15 atm. Feed gas composition was varied from 6 to 20% CH4/balance N2 and steam, with a feed H2O/CH4 ratio = 4. Two sources of dolomite were used; Rockwell and Stonelite. Particle sizes of dolomite and catalyst were 75>dp>150 μm and 300>dp>425 μm, respectively and were inversely varied. Results show that at 550°C Ca(OH)2 formation is possible, thus reducing the available CaO for carbonation, negatively affecting the performance of the SER system, while 650°C reached the SER thermodynamic equilibrium (TE). The use of dolomite approached the TE of the feed gas compositions studied, disregarding of its source. Kinetic effects observed in the tests suggest that small dolomite and large catalyst particles favor the decrease of CO2 diffusion effects.

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Çakırca, Emine E., Gizem N Tekin, Oğuzhan İlgen und Ayşe N Akın. „Catalytic activity of CaO-based catalyst in transesterification of microalgae oil with methanol“. Energy & Environment 30, Nr. 1 (17.07.2018): 176–87. http://dx.doi.org/10.1177/0958305x18787317.

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In this work, activities of modified dolomite catalysts using calcium acetate in the heterogeneously catalyzed transesterification of microalgae oil with methanol were investigated. Modified catalysts were prepared via wet impregnation method and calcined 850°C for 2 h. Reaction conditions were examined as the catalyst type, amount of catalyst, methanol/microalgae oil molar ratio, and reusability of the catalyst using the dolomite and modified dolomite catalysts. When investigated reusability of the modified dolomite catalyst in the transesterification of microalgae oil with methanol, catalyst was reused three times with a small loss of activity. After fourth run, reused catalyst was calcined again and got similar activity to the first run. The highest fatty acid methyl esters (FAME) yield of 90% was obtained when the reaction was performed with methanol/microalgae oil molar ratio of 6:1, catalyst amount of 3%, and reaction temperature at 65°C for 3 h by using the 30% CaO/dolomite catalyst.

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Dissertationen zum Thema "Calcined dolomite"

Menšíková, Barbora. „Vliv složení plynu na čištění plynu bariérovým filtrem“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443177.

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The diploma thesis deals with the issue of pollution of the generated gas after the gasification process and its subsequent cleaning using a barrier filter. The theoretical part of thesis consists of research on the gasification process, the effects on the gasification process, pollutants in the gas and gas cleaning with a focus on the purification of gas from tar. The experimental part of this thesis is devoted to the gasification itself in a fluidized bed gasification reactor in order to test the effect of the catalyst, which was calcined dolomite, the composition of the gas at variable parameters of water vapor and the temperature inside the laboratory filter.

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Coffey, Melody Roy. „Microbially Mediated Porosity Enhancement in Carbonate Reservoirs: Experiments with samples from the Salem, Sligo, and Smackover Formations“. MSSTATE, 2004. http://sun.library.msstate.edu/ETD-db/theses/available/etd-10122004-105856/.

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This study used petrographic thin sections, scanning electron microscopy, and confocal laser microscopy to document microbially mediated dissolution of carbonate reservoir rocks. The samples studied came from three carbonate units that are hydrocarbon reservoirs; the Salem, Sligo, and Smackover formations. These samples were inoculated with bacteria, and then treated with nutrient solutions followed by ethanol to promote generation of acetic acid by bacteria. Dissolution occurred in calcite-dominated rocks and in dolomitized rocks. Noticeable changes first occurred after nine weeks of ethanol treatment and significant change only occurred after twelve weeks of ethanol treatment. The size of the vuggy pores created increased from 1 µm or less to over 5 µm, and rarely over 10 µm, in length.

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Soares, Roberto Arruda Lima. „Efeito da adi??o de carbonatos em formula??o de massa para revestimento cer?mico utilizando mat?rias-primas do Piau?“ Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12756.

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Made available in DSpace on 2014-12-17T14:07:03Z (GMT). No. of bitstreams: 1 RobertoALS_TESE1.pdf: 2084680 bytes, checksum: 363c20f74fc941226fbec8734689dfb7 (MD5) Previous issue date: 2010-05-24
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Piau? state is a major producer of traditional red ceramic burning as bricks, tiles and ceramic tiles, with its main production center located in the city of Teresina. The state has large reserves of raw materials that can be used in the ceramic coating as clays, quartz, talc and carbonates. However, in the preparation of ceramic bodies using only a mixture of clays with different characteristics. The study aims to evaluate the effect of adding two types of carbonates in the ceramic semiporous mass coating produced in Piau? and then to verify the potential use of these carbonates as supplementary raw material product manufactured or the feasibility of obtaining a ceramic plate that meets the specifications for the porous coating. For this, were characterized the ceramic Piau? coating mass, a calcitic carbonate and a dolomitic, were made in the levels of 2, 4, 8, 16, and 32%. The masses were formed by pressing and burneds in two environments: a laboratory furnace (1080?C, 1120?C, 1140?C, and 1160?C) and an industrial furnace (1140?C). Then, following tests of linear shrinkage water absorption, apparent porosity, bulk density and flexural strength. Furthermore, the fired specimens were tested for their macrostructure and microstructure. The results showed the possibility of using the carbonate in ceramic mass flooring produced in Piau?, as added in small proportions improved dimensional stability and increased mechanical strength of ceramics pieces. It also proved itself possible to produce porous coating when added in higher levels
O Estado do Piau? ? um grande produtor de cer?micas tradicionais de queima vermelha como tijolos, telhas e revestimentos cer?micos, com seu principal p?lo produtivo localizado no munic?pio de Teresina. O Estado possui grandes reservas de mat?rias-primas que podem ser utilizadas no setor cer?mico de revestimento como argilas, quartzo, talco e carbonatos. Por?m, na elabora??o das massas cer?micas se utiliza uma mistura de argilas com caracter?sticas diferentes. O presente trabalho tem como objetivo avaliar o efeito da adi??o de dois tipos de carbonatos em uma massa cer?mica de revestimento semiporoso produzido no Piau?, e assim verificar a potencialidade da utiliza??o destes carbonatos como mat?ria-prima complementar do produto fabricado ou a viabilidade de se obter uma placa cer?mica que atenda as especifica??es para o revestimento poroso. Para isso, foram caracterizadas a massa cer?mica de revestimento piauiense, um carbonato calc?tico e outro dolom?tico, ambos oriundos de jazidas localizadas pr?ximas a Teresina - PI. As adi??es na massa cer?mica de cada carbonato foram feitas nos teores de 2, 4, 8, 16 e 32%. As massas foram conformadas por prensagem e queimadas em dois ambientes: forno de laborat?rio (1080?C, 1120?C, 1140?C e 1160?C) e forno industrial (1140?C). Em seguida, realizados ensaios tecnol?gicos de perda ao fogo, retra??o linear, absor??o de ?gua, porosidade aparente, massa espec?fica aparente e resist?ncia mec?nica ? flex?o. Al?m disso, as amostras queimadas foram avaliadas em sua macroestrutura e microestrutura. Os resultados mostraram a possibilidade de se utilizar os carbonatos na massa cer?mica do revestimento produzido no Piau?, pois adicionado em pequenas propor??es melhorou a estabilidade dimensional e aumentou a resist?ncia mec?nica das pe?as cer?micas. Tamb?m se mostrou vi?vel para produ??o de revestimento poroso quando adicionado em teores mais elevados

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Kushnir, Alexandra Roma Larisa. „An experimental investigation of the mechanical behaviour of synthetic calcite-dolomite composites“. Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43299.

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The role of dolomite on the strength and evolution of calcite-dolomite fold and thrust belts is largely unknown. Field investigations indicate that, under upper- to mid-crustal conditions, strain in natural systems is localized in calcite, resulting in a ductile response, while dolomite deforms in a brittle manner. The effect of dolomite on limestone rheology, and the potential for strain localization in composites have not yet been fully quantified. I conducted 11 constant displacement rate (3x10⁻⁴ and 10⁻⁴ s⁻¹), high confining pressure (300 MPa), and high temperature (750°C and 800°C) torsion experiments to address the role of dolomite on the strength of calcite-dolomite composites. Starting materials were formed by hot isostatic pressing mixtures of dolomite and calcite powders (given as Dm%: Dm25, Dm35, Dm51, and Dm75) and were deformed up to a maximum shear strain of ~5. Mechanical data show a considerable increase in yield strength with increasing dolomite content. Microstructural analysis shows that dolomite grains <~50 μm are characterized by diffuse and poorly defined grain boundaries; in Dm25 and Dm35, high aspect ratio dolomite grains are aligned into a foliation. Dolomite grains >~50 μm are characterized by well-defined grain boundaries and cleavage-controlled fracture. Electron backscatter diffraction (EBSD) shows no crystallographic preferred orientation (CPO) development in dolomite, but optical microscopy confirms brittle deformation of dolomite grains by Mode I cracks, shear fractures, and subsequent grain size reduction. Calcite grains are internally strain-free, equiaxed to tabular in shape, and characterized by triple-junction grain boundaries. EBSD confirms a distinct CPO of calcite c-axes perpendicular to the direction of maximum stretching. The microstructure of calcite aggregates suggests grain boundary sliding, accommodated by diffusion and dislocation glide, which accommodates high shear strains without significant change in grains shape and size. Dolomite is essentially undeformed in run products with less than 35% dolomite; calcite accommodates most of the displacement in these experiments. In contrast, for dolomite contents greater than 51%, dolomite accommodates displacement by brittle processes. My experiments provide insights into the processes controlling rheology within bimodal calcite-dolomite systems, suggesting that a minimum dolomite-content exists (between 35% and 51%) above which dolomite significantly influences composite strength.

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Goudalier, Maryline. „Dolomitisation des calcaires du Frasnien moyen en Belgique : contrôle sédimentaire, diagénétique et tectonique“. Lille 1, 1998. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1998/50376-1998-423.pdf.

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Les fabriques dolomitiques secondaires ont ete etudiees dans les unites parautochtone et allochtone des series paleozoiques de la belgique meridionale. Les phases tectoniques paleozoique et mesozoique ont affecte les calcaires primaires et les dolomies secondaires. Des plissements et des chevauchements majeurs de direction est-ouest ont deforme les series. La faille du midi est un exemple de decollement qui separe l'allochtone du parautochtone. Les resultats ont ete obtenus sur deux groupes d'echantillons (affleurements et sondages). Les corps massifs de dolomies secondaires, observables en carrieres ont ete exploites pendant des decennies. Environ 260 echantillons ont ete analyses macroscopiquement (sections polies, repliques d'acetate et coloration). L'etude petrographique caracterise les dolomies secondaires et les ciments calcitiques. La geochimie des phases minerales (cathodoluminescence, microsonde) et l'etude microthermometrique d'echantillons representatifs determinent une chronologie au sein de la paragenese observee. La dolomitisation des dolomies du frasnien moyen en belgique a ete, en premier lieu, controlee par le contexte sedimentaire (diagenese precoce). Les fabriques dolomitiques mimetiques et destructive presentent une teinte rouge de faible intensite (en cathodoluminescence). L'homogeneite des caracteristiques selon les differentes fabriques (fdm1, fdm2 et fdd) suggere une volution pendant l'enfouissement (diagenese tardive). Les cimentations calcitiques (non ferrifere et ferrifere) posterieures a la dolomitisation ont pris place pendant une tectonique fin-varisque et post-varisque.

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Wang, Tingting. „Breakdown of the Ostwald step rule - The precipitation of calcite and dolomite from seawater at 25 and 40 °C“. Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114570.

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The scarcity of recent dolomite contrasts strongly with its common abundance in ancient sedimentary rocks, leading to the paradox commonly referred to as the "dolomite problem". Despite many attempts, dolomite has never been precipitated at room temperature from natural seawater in the absence of bacterial mediation. It has been proposed that natural environments conducive to dolomite formation may be dynamic systems, in which the water chemistry (pH, alkalinity, saturation state with respect to specific minerals) fluctuates in response to variations in environmental conditions such as biological activity, temperature, salinity. Nevertheless, there is little literature dedicated to simulating such environmental changes. In this study, we simulated the dynamic nature of natural environments by alternating between intervals of dissolution and precipitation in natural seawater through purging gases of different CO2 partial pressures (pCO2). By alternating between periods of aragonite supersaturation and undersaturation, aragonite was obtained during the first few cycles at 25 and 40oC, but only calcite was detected in the 18th cycle of the experiments at 25oC. In contrast, neither calcite nor dolomite were detected in the precipitates after 20 and 25 cycles at 40oC. Parts of the objectives in this study—breaking the Ostwald Step Rule and synthesizing calcite from natural seawater at 25oC—were achieved, but the 40oC experiment did not yield the result we hoped for. One possible explanation is that stable calcite nuclei may not have accumulated to a high enough concentration after 25 cycles at 40oC that sufficient calcite surfaces were available to offset the nucleation of aragonite. Another explanation is that stable pre-nucleation clusters, whose conformation may also be dependent on solution composition and temperature, control the crystallization of a set calcium carbonate polymorph.
La rareté de la dolomite récente contraste avec son abondance dans des roches sédimentaires anciennes, conduisant au paradoxe communément appelé "le problème de la dolomite". Malgré de nombreuses tentatives, en l'absence de médiation bactérienne, la dolomie n'a jamais été précipitée à la température ambiante à partir de l'eau de mer naturelle. Il a été proposé que les environnements naturels propices à la formation de dolomite peuvent être des systèmes dynamiques, pour lesquels la chimie de l'eau (pH, alcalinité, l'état de saturation à l'égard de minéraux spécifiques) fluctue en réponse aux variations des conditions environnementales (par ex.: l'activité biologique, la température, la salinité). Cependant, il y a très peu de la littérature consacrée à la simulation de ces changements environnementaux. Dans cette étude, nous avons simulé, en alternant entre des intervalles de dissolution et de précipitation dans l'eau de mer naturelle par une purge de gaz de différentes pressions partielles en CO2 (pCO2), la nature dynamique des milieux naturels. En alternant entre des périodes de sur-saturation et sous-saturation par rapport à l'aragonite, seule de la calcite a été détectée après le 18ième cycle à 25 °C. En revanche, nous n'avons observé ni calcite et ni dolomite dans les précipités aragonitiques après 20 et 25 cycles à 40 °C. Une partie des objectifs de cette étude - contrer règle d'Ostwald sur les transformations successives (états intermédaires) et la synthèse de calcite dans l'eau de mer naturelle à 25 °C - ont été atteints, mais l'expérience à 40oC n'a pas donné le résultat espéré. Une explication possible est que des noyaux stables de calcite ne se sont pas accumulés à une concentration assez élevée après 25 cycles à 40 °C, que suffisamment de surface calcitique était disponible pour contrer la nucléation de l'aragonite. Une autre explication est que la stabilité des grappes de pré-nucléation, dont la conformation dépend possiblement de la chimie de la solution et de la température, se forment et contrôlent la cristallisation d'un polymorphe spécifique de carbonate de calcium.

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ESTRADA, MALDONADO C. FABIOLA. „Contribution a l'etude du systeme ca-mg-co#2-h#2o : dissolution de la calcite et de la dolomite dans l'eau de mer et dans des solutions de nacl de 0 a 300c“. Toulouse 3, 1991. http://www.theses.fr/1991TOU30223.

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Le but de ce travail est de contribuer a la connaissance des lois qui regissent la stabilite des carbonates dans la nature, en particulier dans les solutions hydrothermales et dans les eaux interstitielles des sediments marins. Apres analyse des donnees de la litterature, l'auteur est amenee, entre autres, a mesurer jusqu'a cent degres les constantes apparentes de dissociation de l'acide carbonique et le produit de solubilite de la calcite dans l'eau de mer. De meme, les premieres determinations experimentales du produit de solubilite de la dolomite a haute temperature sont realisees dans des solutions de chlorure de sodium. Pour tous les parametres etudies, des interpolations en fonction de la temperature sont proposees en tenant compte des mesures effectuees et des donnees de la litterature. A l'issue de cette etude il est etabli que le produit de solubilite de la calcite dans l'eau de mer diminue lorsque la temperature augmente, effet difficile a deceler uniquement a partir des donnees en dessous de vingt-cinq degres. Des essais de dissolution de longue duree montrent que l'eau de mer est sursaturee par rapport a l'anhydrite des quatre-vint-dix degres et suggerent que la calcite joue un role dans la cristallisation de phyllosilicates magnesiens. Par ailleurs, des essais a deux cents degres conduisant a la dolomitisation de la calcite en milieu marin permettent de calculer le produit de solubilite de l'anhydrite et mettent en evidence les presences simultanees de calcite magnesienne, dolomite calcique et magnesite calcique. Pour tous les parametres etudies, a l'exception de la constante de dissolution du gaz carbonique, les courbes en fonction de la temperature dans l'eau de mer s'ecartent sensiblement des courbes dans les solutions de chlorure de sodium dans la gamme de concentration consideree

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Lundin, Linnéa. „Interpretation of the P-T-XCO2 environment during metamorphism of carbonates, central Utö, Stockholm archipelago“. Thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-93279.

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This thesis attempts to interpret the metamorphic condition and fluid composition experienced by metacarbonates on Utö, located in the south-eastern parts of the Stockholm archipelago. Utö is a part of the Svecofennian domain, and the area Bergslagen, that has hosted several mines over the last millennia. The bedrock in this area has been dated by the U-Pb technique to 1.90-1.87 Ga, placing it in the Paleoproterozoic era (Allen et al. 1996, Lundström et al. 1998). The rocks, of the studied area on the island of Utö, are mainly metacarbonates with a varying purity and thin layers of volcanic ash. These rocks become more felsic towards the north-western coast as the layers of felsic ash become more dominant. To determine the P-T-XCO2 of metamorphism, metacarbonates were examined, in the field, in thin sections and mineral chemistry was determined by SEM analysis. Three samples were collected along a 1km transect, along which the assemblage calcite + dolomite + quartz + tremolite + diopside was observed. Petrographic and SEM analysis were performed to gather chemical data from coexisting calcite and dolomite in order to calculate temperature using the calcite-dolomite geothermometer. Chemical data from the SEM analysis were also run with AX and THERMOCALC together with pressure data received from a study by Engström (2011) of the adjacent island, Persholmen, to generate a T- XCO2 diagram. Pressure was estimated to 3.1 +/- 1.3 kbars, temperature calculated to 442°C 30°C and XCO2 to range from 0,00067-0,0038 with the standard deviation taken in to account. These results record equilibration with a CO2-bearing hydrous fluid at greenschist facies conditions.
Metamorphic map of Sweden

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Fox, Michael E. „An Assessment of Shock Metamorphism for Jeptha Knob, A Suspected Impact Crater in North-Central Kentucky“. Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1415624495.

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Bourrouilh-Le, Jan Françoise G. „Diagenese des carbonates de plates-formes, recifs et mangroves, en atlantique et pacifique. Controle de la diagenese par les variationsthermo-glacio-eustatiques d'emersion-submersion. Aragonite, calcite, dolomite, phosphate“. Paris 6, 1990. http://www.theses.fr/1990PA066061.

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Les controles globaux de la diagenese des carbonates de plates-formes, recifs et mangroves en atlantique et pacifique, allant de l'holocene a 23 ma, sont au nombre de 6: 1. La sedimentation de haute energie, 2. Les paleotemperatures oceaniques, 3. Les variations du niveau des oceans, 4. Les phases d'emersion-submersion, 5. Les sols phosphato-bauxitiques, 6. Les relations avec l'expansion oceanique. En consequence, les variations thermo-glacio-eustatiques controlent les variations de la nappe phreatique ou lentille de ghyben-herzberg des plates-formes, iles et atolls, et donc la diagenese. La diagenese aragonitique comporte lithification et dissolution. La diagenese calcitique augmente avec le temps, l'ion sr#+#+ en etant le marqueur. La diagenese bauxitique et surtout phosphatee nait par evolution pedogenetique de produits volcano-sedimentaires pieges dans les karsts. Elle contribue a la diagenese dolomitique (li, mn, mg. . . ). La diagenese dolomite dans 2 exemples: mangrove d'andros, bahama, et facies corallien a rhodolithes du pacifique, montre le role d'ions tels que li, na, k, mn, et le transport de l'ion mg#+# par les molecules d'eau. La dolomitisation est une suite de relais ioniques ou n'interviennent que les equilibres d'hydratation et de deshydratation de l'ion mg#+#+. Li, mn, na, k, sont des catalyseurs et les mineraux pre- ou paradolomitiques pourraient se former. Ces differentes diageneses sont contemporaines et concurrentes, pour donner un etat de carbonate plus stable: calcite, puis dolomite

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Bücher zum Thema "Calcined dolomite"

Jan, F. G. Bourrouilh-le. Plates-formes carbonatées et atolls du centre et sud Pacifique: Stratigraphie, sédimentologie, minéralogie et géochimie, diagenèses et émersions-- aragonite, calcite, dolomite, bauxite et phosphate. Orléans, France: BRGM, 1996.

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Buchteile zum Thema "Calcined dolomite"

Buğdayci, Mehmet, Ahmet Turan, Murat Alkan und Onuralp Yücel. „Magnesium Production from Calcined Dolomite via the Pidgeon Process“. In Magnesium and Its Alloys, 47–56. First edition. | Boca Raton, FL : CRC Press/Taylor & Francis Group, [2020] | Series: Metals and alloys: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045476-3.

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Hu, Wen-xin, Nai-xiang Feng, Yao-wu Wang und Zhi-hui Wang. „Magnesium Production by Vacuum Aluminothemic Reduction of A Mixture of Calcined Dolomite and Calcined Magnesite“. In Magnesium Technology 2011, 43–47. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118062029.ch11.

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Hu, Wen-Xin, Nai-Xiang Feng, Yao-Wu Wang und Zhi-Hui Wang. „Magnesium Production by Vacuum Aluminothermic Reduction of a Mixture of Calcined Dolomite and Calcined Magnesite“. In Essential Readings in Magnesium Technology, 121–25. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118859803.ch20.

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Hu, Wen-xin, Nai-xiang Feng, Yao-wu Wang und Zhi-hui Wang. „Magnesium Production by Vacuum Aluminothermic Reduction of a Mixture of Calcined Dolomite and Calcined Magnesite“. In Magnesium Technology 2011, 43–47. Cham: Springer International Publishing, 2011. http://dx.doi.org/10.1007/978-3-319-48223-1_11.

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Hu, Wen-xin, Nai-xiang Feng, Yao-wu Wang und Zhi-hui Wang. „Magnesium Production by Vacuum Aluminothermic Reduction of a Mixture of Calcined Dolomite and Calcined Magnesite“. In Essential Readings in Magnesium Technology, 121–25. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48099-2_20.

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Taralas, G. „Cyclohexane-Steam Cracking Catalysed by Calcined Dolomite [CaMg(O)2]“. In Developments in Thermochemical Biomass Conversion, 1086–100. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-1559-6_88.

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Yucel, Onuralp, Selen Yiğit und Bora Derin. „Production of Magnesium Metal from Turkish Calcined Dolomite Using Vacuum Silicothermic Reduction Method“. In Materials Science Forum, 39–42. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-968-7.39.

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Al-Dousari, Ali, und Muntha Bahbahani. „Mineralogy (XRD)“. In Atlas of Fallen Dust in Kuwait, 95–119. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66977-5_4.

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Abstract The two main particle size components of the dust samples were subjected to mineralogical analysis to identify the mineral constituents and determine their frequency percentage in each textural class; the fine sand (particle size between 0.125 and 0.063 mm) and Mud (less than 0.063 mm). The average percentage of minerals was mapped out for each season i.e. March, June, September and December 2010 showing the high and low mineral concentration in areas in Kuwait covering the mineral concentrations of Calcite, Carbonate, clay minerals, dolomite, feldspars, and quartz.

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Green, Owen R. „Field Staining Techniques for Determining Calcite, Dolomite and Phosphate“. In A Manual of Practical Laboratory and Field Techniques in Palaeobiology, 55–58. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-017-0581-3_6.

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Weiss, L. E., und F. J. Turner. „Some Observations on Translation Gliding and Kinking in Experimentally Deformed Calcite and Dolomite“. In Flow and Fracture of Rocks, 95–107. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm016p0095.

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Konferenzberichte zum Thema "Calcined dolomite"

Senthoorselvan, Sivalingam, Stephan Gleis, Spliethoff Hartmut, Patrik Yrjas und Mikko Hupa. „Cyclic Carbonation and Calcination Studies of Limestone and Dolomite for CO2 Separation From Combustion Flue Gases“. In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50987.

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Naturally occurring limestone and dolomite samples, originating from different geographical locations, were tested as potential sorbents for carbonation/calcination based CO2 capture from combustion flue gases. Samples have been studied in a thermo gravimetric analyzer under a simulated flue gas conditions at three calcination temperatures, viz., 750°C, 875°C and 930°C for four Carbonation Calcination Reaction (CCR) cycles. The dolomite sample exhibited the highest rate of carbonation than the tested limestones. At 3rd cycle, its CO2 capture capacity per kg of sample was nearly equal to that of Gotland, the highest reacting limestone tested. At 4th cycle it surpassed Gotland, despite the fact that the CaCO3 content of Sibbo dolomite was only 2/3 of Gotland. Decay coefficients were calculated by a curve fitting exercise and its value is lowest for Sibbo dolomite. That means, most probably its capture capacity per kg of sample would remain higher, well beyond the 4th cycle. There was a strong correlation between the calcination temperature, specific surface area of the calcined samples and degree of carbonation. It was observed that higher the calcination temperature lower the sorbent reactivity. The BET measurements and SEM images provided quantitative and qualitative evidences to prove this. For a given limestone/dolomite sample, sorbent’s CO2 capture capacity was depend on the number of CCR cycles and the calcination temperature. In a CCR loop, if the sorbent is utilized only for a certain small number of cycles (<20), the CO2 capture capacity could be increased by lowering the calcination temperature. According to the equilibrium thermodynamics, the CO2 partial pressure in the calciner should be lowered to lower the calcination temperature. This can be achieved by additional steam supply into the calciner. Steam could then be condensed in an external condenser to single out the CO2 stream from the exit gas mixture of the calciner. A calciner design based on this concept is illustrated.

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Gu, Kai, Fei Jin, Abir Al-Tabbaa und Bin Shi. „Initial Investigation of Soil Stabilization with Calcined Dolomite-GGBS Blends“. In Geo-Shanghai 2014. Reston, VA: American Society of Civil Engineers, 2014. http://dx.doi.org/10.1061/9780784413401.015.

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Zhang, Wangnian, Ning Deng, Weijie Liang, Lili Peng und Xin Zhao. „Yanfeng calcined dolomite two-step preparation of calcium magnesium sand“. In 3rd International Conference on Material, Mechanical and Manufacturing Engineering (IC3ME 2015). Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/ic3me-15.2015.2.

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Royani, Ahmad, Eko Sulistiyono, Agus Budi Prasetiyo und Rudi Subagja. „Extraction of magnesium from calcined dolomite ore using hydrochloric acid leaching“. In PROCEEDINGS OF THE INTERNATIONAL SEMINAR ON METALLURGY AND MATERIALS (ISMM2017): Metallurgy and Advanced Material Technology for Sustainable Development. Author(s), 2018. http://dx.doi.org/10.1063/1.5038299.

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Trass, O., E. A. J. Gandolfi, E. J. Anthony und M. Maryamchik. „Reactivation of Fluidized Bed Combustor Ashes: Economic Evaluation and Implementation“. In 18th International Conference on Fluidized Bed Combustion. ASMEDC, 2005. http://dx.doi.org/10.1115/fbc2005-78121.

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When high-sulfur-content coal or coke is used as fuel in fluidized bed combustors, a large excess of limestone or dolomite must be added for good SOx capture. All of the limestone is calcined but only 30–40% is actually sulfated. The resultant ashes are difficult to dispose of because of the free calcium oxide. These ashes can be reactivated for further SOx capture. A proposed, economic process involves wet grinding of the ashes with sufficient excess water to allow both complete hydration and good grinding conditions. To prevent cementitious solidification of the wet product, it is then mixed with selected dry materials, for example fine coal, to absorb the excess water. Wet waste coal fines or sludges may also be used, then both to provide the water and prevent solidification. The product is then granulated with the cementitious reactions providing a binder for the granules. Good results with large additional SOx capture have been observed both in a small pilot-sized CFBC and during a 54-hour utility boiler test in a 35 MWt boiler. Calcium utilization was nearly doubled, with significant reduction of CO2 emissions. Based on the test results, quick equity payback is expected with savings from reduced limestone purchase and ash disposal costs. In collaboration with The Babcock and Wilcox Company (B&W), a long test program at the Southern Illinois University in Carbondale, IL is planned.

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Crnkovic, Paula M., Ivonete A´vila, Fernando E. Milioli und Josmar D. Pagliuso. „Effect of Sorbent Physical Structure—Pore Size Distribution and Surface Morphology—on the Limestone Capability for Sulfation“. In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67645.

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Sulfur oxides are present in the gases from burning coals and these pollutants are harmful to the environment. Sulfur removal in the fluidized bed reactor applying limestones is an efficient technology. During sulfation, the formation of CaSO4 leads to the partial or complete blockade of the particle interior, resulting in a low efficiency of the use of limestones. As the desulphurization capacities of the sorbents are strongly affected by thermal condition, this paper focuses on the study of the development of the particles’ physical structure before and during sulfation reaction. The experiments were performed for two Brazilian limestones, a calcite and a dolomite. The particles were well characterized by BET analysis and mercury porosimetry and the behavior of the sorbents was observed through thermogravimetry analysis (TGA). The morphological analysis of the surface of both raw calcite and dolomite particles indicated that dolomite was a less compact sorbent. However, after calcination and sulfation, the change in pore and voids distributions showed that for dolomite both swelling and partial pore filling could take place, whereas for calcite the spaces between particles were maintained constant, possibly owing to a less intense swelling. In 30 min of reaction under air atmosphere TGA measurements provided conversions of 0.40 ±0.061 for the calcite, and 0.55 ±0.089 for the dolomite. The results showed strong dependence on meso and macropores region with high conversion of the sorbents. The reactivity differences between calcite and dolomite can also be explained based on the swelling of the particles.

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Chen, Guanyi, Qiang Li, Xiaoyang Lv, Na Deng und Lifei Jiao. „Production of Hydrogen-Rich Gas Through Pyrolysis of Biomass in a Two-Stage Reactor“. In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53582.

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Biomass is quite abundant in the world, particularly in some countries like China. China has large quantities of straw and/or stalk-origin biomass resources and the attention is currently being paid to the exploitation of these resources to produce energy products via different technical solutions, among of which pyrolysis of biomass to produce hydrogen-rich gas is very promising as hydrogen is a very clear energy carrier. In this work, pyrolysis of rice straw, corn stalk and sawdust was carried out in a two-stage reactor (the first-stage reactor is a conventional fixed-bed pyrolyser, and the second-stage reactor is a catalytic fixed bed) to produce hydrogen-rich gas. The effect of catalytic bed on the pyrolysis behaviour have been investigated, with the emphasis on final product particularly hydrogen. The operation of the catalytic reactor appears significant in promoting biomass pyrolysis towards the production of gaseous products, especially hydrogen. At 750°C of the pyrolyser with rice straw as fuel, the use of the catalytic bed leads to the increases of gas yield from 0.41 Nm3/kg to 0.50 Nm3/kg, approximately 22% increase, and of H2 concentration from 33.79% to 50.80% in volume, approximately 50.3% increase, respectively. Compared with calcined dolomite, fresh nickel-based catalyst shows stronger catalytic effect on the pyrolysis of rice straw as its use in the catalytic bed results in the increase of gas yield from 0.41 Nm3/kg to 0.56 Nm3/kg, approximately 36.6% increase, and the increase of H2 concentration from 33.79% to 59.55% in volume, approximately 76.2% increase. Furthermore, two catalysts follow the same trend for the pyrolysis of corn stalk and sawdust. At temperature of 815°C, catalysts also follow the same trend. Catalytic bed can significantly reduce the level of tar which is carried out with the producer gas, to less than 1% of original level. Catalyst load or gas space velocity (hourly) has the influence on the gas yield and H2 concentration. 30% of load, i.e. gas space velocity (hourly) 0.9 × 104 h−1, appears reasonable. Beyond that, gas yield and H2 concentration remain almost unchanged.

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Rady, Ayten, und H. A. Nasr-El-Din. „Iron Precipitation in Calcite, Dolomite and Sandstone Cores“. In SPE Russian Petroleum Technology Conference. Society of Petroleum Engineers, 2015. http://dx.doi.org/10.2118/176574-ms.

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Rady, Ayten, und H. A. Nasr-El-Din. „Iron Precipitation in Calcite, Dolomite and Sandstone Cores (Russian)“. In SPE Russian Petroleum Technology Conference. Society of Petroleum Engineers, 2015. http://dx.doi.org/10.2118/176574-ru.

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Rowlands, Neil, und Robert A. Neville. „Calcite and dolomite discrimination using airborne SWIR imaging spectrometer data“. In SPIE's 1996 International Symposium on Optical Science, Engineering, and Instrumentation, herausgegeben von Michael R. Descour und Jonathan M. Mooney. SPIE, 1996. http://dx.doi.org/10.1117/12.258085.

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