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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.
191

CaracterizaÃÃo de Ãguas produzidas provenientes de plataformas marÃtimas da bacia do Cearà / Water characterization produced from offshore platforms of the Cearà basin

Ana KÃtia de Sousa Braz 30 April 2014 (has links)
Nesse trabalho, foram caracterizadas 238 amostras de Ãgua produzida, oriundos de quatro campos de produÃÃo diferentes, todos provenientes de campos marÃtimos da bacia do CearÃ, denominados campo de produÃÃo A, campo de produÃÃo B, campo de produÃÃo C e campo de produÃÃo D. Foram determinados, os Ãnions (Acetato, Cloreto, Formiato, Sulfato) utilizando-se a cromatografia de Ãons; exceto, para o Ãnion Bicarbonato que foi determinado utilizando-se a titulaÃÃo potenciomÃtrica. E, os cÃtions (BÃrio, CÃlcio, EstrÃncio, Ferro Total, LÃtio, MagnÃsio, PotÃssio, SÃdio) utilizando-se a espectrometria de emissÃo Ãptica com plasma acoplado indutivamente. Para tratamento estatÃstico, utilizou-se como ferramenta, a PCA (anÃlise de componentes principais) e a HCA (anÃlise de agrupamento hierÃrquico). Na avaliaÃÃo da qualidade dos dados, utilizou-se o balanÃo iÃnico. Para visualizaÃÃo dos resultados, utilizou-se o grÃfico boxplot, onde se pode observar que o campo de produÃÃo A, seguido do campo de produÃÃo B, possuem tendÃncia à corrosÃo e à incrustaÃÃo, respectivamente. Como tambÃm, o campo de produÃÃo D que apresentou propensÃo à corrosÃo, mas em menor escala. Vale salientar a necessidade de uma caracterizaÃÃo individual das amostras, para conhecimento dos principais constituintes existentes. Pois, esses constituintes podem acarretar elevados custos na manutenÃÃo do processo produtivo da indÃstria petrolÃfera; devido, a corrosÃo do tipo pite, que promove a modificaÃÃo da aparÃncia e estrutura dos aÃos inoxidÃveis, muito utilizados na indÃstria petrolÃfera; e, as incrustaÃÃes, que tendem a se depositar nas paredes das tubulaÃÃes, que podem causar problemas como perda de pressÃo, diminuiÃÃo do escoamento da produÃÃo e aumento no consumo de energia. / In this study, we characterized 238 samples of water produced from four different production fields, all from offshore fields of the Cearà basin, called The field of production, production field B, C production and field production field D. were determined anions (acetate, chloride, formate, sulfate) using ion chromatography; except for the bicarbonate anion was determined using potentiometric titration. And, cations (Barium, Calcium, Strontium, total iron, lithium, magnesium, potassium, sodium) using the optical emission spectrometry with inductively coupled plasma. For statistical analysis, we used as a tool, the PCA (principal component analysis) and HCA (hierarchical cluster analysis). In evaluating the quality of the data, we used the ionic balance. To visualize the results, we used the box plot graph where one can observe that the production field, followed by the production field B, are prone to corrosion and fouling, respectively. As well, the D production field that showed propensity to corrosion, but on a smaller scale. It is worth stressing the need for individual characterization of the samples, to knowledge of the main existing constituents. For these constituents can incur high costs in maintaining the productive process of the oil industry; due to corrosion pitting type, which promotes change the look and structure of stainless steel, widely used in the oil industry; and incrustations which tend to deposit on the walls of pipes, which may cause problems such as pressure loss, decreased production flow and an increase in power consumption.
192

A class of generalized beta distributions, Pareto power series and Weibull power series

Lemos de Morais, Alice 31 January 2009 (has links)
Made available in DSpace on 2014-06-12T18:01:54Z (GMT). No. of bitstreams: 2 arquivo3788_1.pdf: 702720 bytes, checksum: bc4a0f4ac532f594aa3c60b71c963230 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta dissertação trabalhamos com três classes de distribuições de probabilidade, sendo uma já conhecida na literatura, a Classe de Distribuições Generalizadas Beta (Beta-G) e duas outras novas classes introduzidas nesta tese, baseadas na composição das distribuições Pareto e Weibull com a classe de distribuições discretas power series. Fazemos uma revisão geral da classe Beta-G e introduzimos um caso especial, a distribuição beta logística generalizada do tipo IV (BGL(IV)). Introduzimos distribuições relacionadas `a BG L(IV) que tamb´em pertencem `a classe Beta-G, como a beta-beta prime e a beta-F. Introduzimos a classe Pareto power series (PPS), que ´e uma mistura de distribui¸c oes Pareto com pesos definidos pela distribui¸c ao power series, e apresentamos algumas de suas propriedades. Introduzimos a classe Weibull power series (WPS), cujo processo de constru¸c ao ´e similar ao da classe PPS. Apresentamos algumas de suas propriedades e aplica¸c ao a um banco de dados reais. Distribui¸c oes nesta classe t em aplica¸c ao interessante a dados de tempo de vida devido `a variedade de formas da fun¸c ao de risco. Para as classes PPS e WPS, fizemos uma simula ¸c ao para avaliar m´etodos de sele¸c ao de modelo. A distribui¸c ao pareto ´e um caso especial limite da distribui¸c ao PPS, assim como a distribui¸c ao Weibull ´e um caso especial limite da distribui¸c ao WPS.
193

Optical emission from electric arc furnaces

Aula, M. (Matti) 19 January 2016 (has links)
Abstract The main cause of temperature and composition fluctuations in the electric arc furnace (EAF) process is the scrap used as a raw material. Process conditions in EAF can vary significantly from heat to heat because there is no accurate information of scrap composition. Due to harsh process conditions, there are currently few sensors available for direct on-line measurement of the EAF process. In this work new information about stainless steelmaking EAF process conditions is sought with optical emission spectrum measurement. The measurement system relies on transportation of the light emitted from the measured furnace to a remotely situated spectrometer. Analysing the slag composition from the arc emission spectrum was tested in the laboratory and on a pilot scale. The laboratory measurements indicate that changes in the amount of CrOx and MnO in the slag have the highest impact on optical emission spectra. The pilot scale measurements show that the Cr2O3 content of the slag can be measured from the arc emission spectrum using suitable reference lines with an average absolute error of 0.62 %-points and a standard deviation of 0.49 %-points. The results from measurements at Outokumpu Stainless Oy, Tornio Works, indicate that measurement of the optical emission spectrum from industrial EAF is feasible in a practical sense, and can be used in analysing of EAF atmosphere, scrap melting and slag surface. Furthermore, the results of industrial measurements indicate that the atoms in the arc plasma mainly originate from the slag. The measurement of scrap melting could be potentially used in EAF control in optimization of arc voltages and second scrap bucket charging. The potential use of slag CrOx measurements is in optimization of reductant additions as well as defining the further processing of EAF slag. / Tiivistelmä Valokaariuunien ohjaus on perinteisesti ollut uunioperaattorin käsissä. Valokaaariuuniprosessin on-line mittaukseen on olevassa vähän menetelmiä johtuen uunin hyvin haastavaista olosuhteista. Tässä työssä on tutkittu optiseen emissiospektroskopiaan perustuvaa menetelmää uuden jatkuva-aikaisen tiedon tuottamisessa valokaariuuniprosessista. Mittausjärjestelmä perustuu valon keräämiseen mitattavasta uunista valokuidun avulla, joka johtaa valon analysoitavaksi etäälle prosessista sijoitettuun spektrometriin. Mittauksia suoritettiin laboratorio-, pilot- ja tehdas-mittakaavassa. Valokaariuunin kuonan koostumuksen analysointia testattiin laboratorio- ja pilot-mittakaavan uuneilla. Laboratoriomittaukset osoittivat että kuonan komponenteista CrOx ja MnO ja vaikuttavat eniten mitattuun emissiospektriin. Pilot-mittakaavan kokeissa havaittiin, että kuonan Cr2O3-pitoisuutta voidaan mitata valokaaren emissiospektristä 0,62 %-yksikön keskimääräisellä absoluuttisella virheellä ja 0,49 %-yksikkön hajonnalla. Teollisella valokaariuunilla suoritetuista mittauksista havaittiin että optisen emissiospektrin mittaus voidaan suorittaa ilman ylitsepääsemättömiä teknisiä esteitä. Mittauksen tuloksia voidaan puolestaan käyttää kaasufaasin reaktioiden, romun sulamisen ja kuonapinnan ominaisuuksien arvioinnissa. Valokaaren emissiospektrin analyysi osoitti, että valokaaren plasman komponentit ovat pääosin peräisin kuonasta, joka mahdollistaa kuonan koostumuksen arvioinnin valokaaren emissiospektrin perusteella. Romun sulamisen mittausta voidaan prosessinohjauksessa käyttää jänniteportaiden ja toisen korin panostuksen optimointiin. Kuonan kromipitoisuuden mittaamista voidaan puolestaan käyttää pelkistinaineiden lisäyksen optimointiin ja kuonan jatkokäsittelyn valintaan.
194

Analýza vybraných odrůd českého česneku / Analysis of czech garlic varieties

Fähnrichová, Nikola January 2018 (has links)
This master thesis deals with analysis of Czech garlic varieties in comparison with two varieties from abroad. Alliin and carbohydrates were determined by high performance liquid chromatography with diode-array detector or evaporative light scattering detector. Crude proteins were calculated from total content of nitrogen that was determinated by Kjeldahl method. Elementary analysis was performed by inductively coupled plasma optical emission spectrometry. In theoretical part of this thesis is describes botanical characterization and cultivation of garlic, chemical composition of garlic, especially groups of substances which were analysed in this thesis. Principle of used methods is described too. The experimental part of this work deals with sample and calibration solution preparation and process of analysis. Obtained results from analysed substances are summarized in the tables, discussed and compared with results of analysis of other authors. Between Czech and Spanish/Chinese garlic are slight differences. Garlics contain 24,66 g/kg dry weight of alliin. Content of crude proteins in Czech garlic is comparable to Chinese garlic but the Spanish garlic has just half of amount crude proteins. Elementary analysis also includes significant differences. Czech varieties contain higher amount of phosphorus, iron and zinc. On the contrary, content of potassium in foreign garlic is higher than in Czech Republic and the analysed amount is 15 g/kg dry weight.
195

Studium vlivu způsobu chovu slepic na obsah vybraných chemických složek vajec / Influence of the chicken breeding method on the selected chemical constituents of chicken eggs

Michalec, Adam January 2018 (has links)
This diploma thesis is focused on the analysis of egg yolks and egg whites from chickens raised with different breeding methods in the Czech Republic using three analytical methods. The Kjeldahl method was used to determine the proteins, the Soxhlet method was used to determine the lipids and ICP-OES was used for elemental analysis. The theoretical part describes the history of chicken breeding, marking and distribution of eggs and composition of eggs based on various aspects. The main point was the separation of egg yolk and egg white and the subsequent description on the chemical and physiological level. Principle of used methods is also described. The experimental part deals with the preparation of samples, calibration samples and process analysis. All the results of analysed substances are summarized, statistically evaluated and compared with the other literature. For this analysis were used eleven different types of eggs from the Czech Republic from six different categories.
196

Studium autenticity koření a kořenících přípravků / Study of the authenticity of spices and condiments

Štursa, Václav January 2021 (has links)
This disertation deals with geographical authentification of different types of spices and spice preparations. Investigated spice species were garlic (Allium sativum), ground pepper (Capsicum anuum), and dried carrot (Daucus carota). Theoretical part of the disertation describes main qualitative parameters of the examined species and production technology, means of food adulteration and statistic methods used in chemometrics. The aim of this dissertation was to verify the hypothesis whether it is possible to use targeted analytical techniques commonly used in quality control of spices and condiments, and statistical processing of measured data to distinguish samples of spices and condiments of different geographical origin. The use of non-targeted analysis was also investigated. Samples of garlic and ground pepper were used for targeted analysis. The examined parameters were dry matter and moisture of the sample, ash content, total phenolic content according to Folin-Ciocaulteu, carbohydrate content, alliin concentration, total nitrogen content, total color pigment (ASTA), pH of aqueous extract, total fat content, and concentration of selected elements (Ca, Cu, Fe, K, Mn, Mg, Na, P, Zn). The instrumental techniques used were molecular absorption spectrometry, inductively coupled plasma optical emission spectrometry and high performance liquid chromatography. The obtained data were statistically processed by analysis of variance (ANOVA) and principal component analysis (PCA). Using statistical analysis significant differences between samples that came from more distant areas were found. However, samples from closer areas could not be distinguished. The researched hypothesis could not be unequivocally confirmed or refuted. Metabolic fingerprint of carrot samples was determined using non-targeted analysis. Metabolic analysis was performed using the tandem LC-TOF-MS technique. The data were processed by recursive peak extraction (BRE) and subsequently uvaluated with PCA. The samples were divided into clusters according to their origin. Targeted and non-targeted techniques have great potential in verifying the geographical authenticity of different types of spices. However, the main condition is consistent and sufficient sampling, guaranteed information on the origin of the sample and obtaining a sufficient amount of input data for statistical analysis.
197

Fyzikální hydrogely na bázi biopolymerů a tenzidů / Physical hydrogels based on biopolymers and surfactants

Velcer, Tomáš January 2021 (has links)
This doctoral thesis studies the properties and behaviour of phase-separated hydrogels. These can be prepared by interaction of polyelectrolytes with oppositely charged surfactants. Negatively charged polysaccharide hyaluronan and cationic surfactant carbethopendecinium bromide (Septonex), whose properties, behaviour and utilization are described in the first two chapters of theoretical part, were selected for this role. Hyaluronan is naturally-occuring in living organisms and is known for his specific targeting to the tumour cells. Septonex is used as antiseptic and disinfectant. Experimental part of this work is focused on examination of the structure and behaviour of these types of hydrogels especially from rheological point of view. The crucial part of this study was to establish mechanical properties and their dependence on environment. This led to design further studies. Structural analysis was held using the methods of ATR-FTIR, ionic chromatography and ICP-OES helping to measure the inner content of entry materials in the gels and supernatants respectively. The last chapter deals with antimicrobial activity. The results of this study indicate a potential usage of these substances in the field of medical applications.
198

Studium různých metod přípravy vzorku mléka pro analýzu mléka technikou ICP-OES / The study of various methods of preparation of the milk sample for milk analysis by ICP-OES technique

Kaňová, Veronika January 2017 (has links)
The theoretical part of the thesis deals with the chemical composition of cow’s milk, with the description of chosen methods of sample pretreatment and with the description of the used technique ICP-OES. The practical part is aimed at individual preparations of samples and at analysis of chosen chemical elements (Ca, Na, K and Mg). Milk is a really complicated polydisperse system, that’s the reason why the preparation of samples with milk is very important step before the measurement itself. In addition to accuracy choosing the sample adjustment method, other factors such as time, work intensity, or cost need to be considered when. In the thesis a comparison of four selected methods of sample preparation was made: direct analyse of milk, dilution with addition of Triton X-100, wet microwave ashing and destruction of matrix with TMAH (tetramethylammonium hydroxide). Selected elements were analysed with the help of ICP-OES. This diploma thesis builds on the bachelor thesis, which deals with the same problem. Final concentrations were compared with certified values of skimmed powdered milk. Data showed that the most accurate are methods of preparation of wet microwave ashing and destruction of matrix with TMAH. By using these methods, the effect of the dairy matrix that caused problems in the analysis, was largely eliminated. The diluted samples with and without Triton X-100 showed a bigger anomaly of measuring than the mineralization of wet ashing which came to the loss of analyte because of fat elements contained in milk.
199

Posouzení vlivu pasterizace a filtrace na obsah vybraných chemických složek piva / Evaluation of the influence of the pasterization and filtration on selected chemical components of beer

Vopelková, Dominika January 2017 (has links)
The aim of this work was to study the influence of the pasteurization and filtration on selected chemical compounds in beer. Specifically, the influence on elemental composition, content of organic acids, carbohydrates and phenolic substances was studied. Optical emission spectrometry with inductively coupled plasma (ICP-OES) was used for elemental analysis of beer. Analysis of organic acids was evaluated by Ion chromatography. For analysis of carbohydrates was used High performance liquid chromatography with ELSD detector (HPLC-ELSD), phenolic compounds was evaluated by HPLC with diode array detector (HPLC-DAD). Data from analysis of beer was performed by usage of statistical methods (analysis of variance and principal component analysis). Parameters that showed the most significant differences between individual groups of beers were obtained. Correlations between the variables and the technological beer processing operations were found. 12 parameters of total 23 were affected. The effect of filtration and pasteurization was observed in content of the iron, silicon, potassium and magnesium, malate, monosaccharides glucose and fructose and phenolic compounds.
200

Development of new methodologies based on ICP techniques for the elemental and isotopic analysis of bioethanol and related samples

Sánchez, Carlos 28 May 2018 (has links)
The present PhD is focused on the development of new analytical methods based on ICP techniques to carry out the elemental and isotopic analysis of bioethanol samples and other specimens taken along the bioethanol production process. The total sample consumption system, so-called hTISIS, has been used as sample introduction system in ICP-OES for the quantification of major and minor metals, and ICP-MS for the determination of trace metals. The hTISIS has also been successfully set up to carry out the lead isotopic analysis of bioethanol samples. Additionally, metals found in bioethanol have been monitored along the production process of this biofuel to identify the origin of these metals. Finally, volatile organic compounds have been determined in different bioethanol samples to perform the characterization of the matrices and their effect on the accuracy of the methods based on ICP techniques, developed in the present PhD for the elemental and isotopic analysis of these kind of samples. / La presente Tesis Doctoral se centra en el desarrollo de nuevos métodos de análisis basados en técnicas de ICP para llevar a cabo el análisis elemental e isotópico de muestras de bioetanol y muestras tomadas a lo largo del proceso de obtención de dicho biocombustible. Se ha empleado un sistema de consumo total de muestra, conocido como hTISIS, como sistema de introducción de muestras en ICP-OES para la cuantificación de metales mayoritarios y minoritarios, y en ICP-MS para la determinación de metales traza en bioetanol. El sistema hTISIS también se ha empleado con éxito para llevar a cabo el análisis isotópico de plomo en dichas muestras. Además, los metales encontrados en las muestras de bioetanol han sido monitorizados a lo largo del proceso de obtención del mismo para identificar el origen de dichos metales. Finalmente, se han determinado los compuestos volátiles presentes en diferentes muestras de bioetanol, con el objetivo de caracterizar las matrices y como estas pueden afectar a la exactitud de los métodos desarrollados, que emplean técnicas ICP para el análisis elemental e isotópico de este tipo de muestras.

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