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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.
11

Otimização do uso de água em refinarias de petróleo. / Optimization of water use in oil refineries.

Anze, Michele 26 April 2013 (has links)
As refinarias de petróleo utilizam grandes quantidades de água em seus processos e por isso são impelidas a desenvolver fortes programas de redução de seu consumo. O objetivo do presente estudo é a aplicação de metodologia de otimização em problemas de alocação ótima e reuso de água em refinaria de petróleo. Diferentemente dos enfoques tradicionais que buscam tratar os efluentes gerados para atender às legislações ambientais ou para algum tipo de reuso na planta, a metodologia utilizada avalia os processos que usam água, questionando as causas da geração do efluente. Essa abordagem envolve o levantamento de dados industriais, análise dos processos de produção, identificação de oportunidades para aplicar as estratégias de otimização da alocação de água: racionalização, reuso e/ou reciclagem do efluente e, em seguida, a otimização da rede de água. Visando obter uma rede de água que seja aplicável na indústria, desenvolveu-se um procedimento específico baseado em regras heurísticas que representam as restrições reais dos processos. Através deste procedimento, o consumo de água fresca atingido é próximo do valor ótimo encontrado na literatura. As redes de água geradas são simples, com poucas interconexões e, consequentemente, os investimentos necessários para implementação são menores. / Oil refineries consume a large amount of water in their processes and because of that they are urged to develop strong programs to reduce their water consumption. The aim of this study is to apply an water optimization methodology in an oil refinery. Unlike traditional approaches that only search for treating the effluents in order to meet environmental legislation or to reuse in the plant, this methodology evaluates the processes that use water, questioning the causes of the wastewater generation. This approach involves the industrial data collection, analysis of production processes, identification of opportunities to optimize water use: rationalization, reuse and/or recycling of the effluent and, lastly, the water network optimization. Looking for a water network that is applicable in the industry, in this study it was also developed a specific optimization procedure based on heuristic rules representing the constraints of the actual processes. Through this procedure, freshwater consumption was found to be close to that of the theories found in the literature. The water networks generated are simple, with few interconnections and, consequently, the investments required to implement them are small.
12

Minimizing the sulphur content in Kraft lignin

Svensson, Sara January 2008 (has links)
<p>The aim of this project is to investigate the possibilities of minimizing the sulphur content in Kraft lignin. Kraft lignin contains about 1.5 to 3% sulphur. The sulphur is believed to be present in lignin as inorganic sulphur, as elemental sulphur, as adsorbed polysulphide and/or as organically bound sulphur. For the determination of these different types of sulphur components, different approaches and methods were used. For the determination of inorganic sulphur, lignin was washed with water at pH 6 and pH 2 and the wash waters were analysed with ion chromatography (IC). For the determination of total sulphur content in the lignin, two methods were used; Schöniger combustion followed by ion chromatography (IC) and wet digestion followed by inductively coupled plasma (ICP). The elemental sulphur content in water-extracted lignin was determined after n-pentane extraction. ICP analysis was performed on the washed lignin.</p><p>Calcium present in the lignin may bind polysulphides and thus be a source of the observed sulphur. The lignin was thus ion-exchanged to remove any calcium. To further investigate how the sulphur content in lignin can be decreased, two different types of reactions were performed on lignin; oxidation and reduction. The oxidation reactions were made in sodium hydroxide with oxygen at different temperatures and time on both original and water-extracted lignin. The reduction reactions were made on water-extracted lignin with Raney nickel in three different solvent systems: methanol: water, acetone: water and sodium hydroxide.</p><p> </p><p>The original lignin contained 2.6% sulphur as determined by ICP. Washing lowered the content to 1.85% sulphur. By n-pentane extraction the elemental sulphur was lowered to a level of 1.82% sulphur, which was considered to be organically bound sulphur. Neither the ion exchange nor the oxidation lowered the sulphur content significantly.</p><p> </p><p>The reduction reactions successfully the organically bound sulphur from 1.82% to a level of 0.54%.</p><p> </p><p>The relative distribution of the sulphur content in the studied softwood lignin was as follows: about 29% as inorganic sulphur, about 1% as elemental sulphur and approximately 70% as organically bound sulphur, of which 49% could be removed by Raney nickel.</p>
13

Minimizing the sulphur content in Kraft lignin

Svensson, Sara January 2008 (has links)
The aim of this project is to investigate the possibilities of minimizing the sulphur content in Kraft lignin. Kraft lignin contains about 1.5 to 3% sulphur. The sulphur is believed to be present in lignin as inorganic sulphur, as elemental sulphur, as adsorbed polysulphide and/or as organically bound sulphur. For the determination of these different types of sulphur components, different approaches and methods were used. For the determination of inorganic sulphur, lignin was washed with water at pH 6 and pH 2 and the wash waters were analysed with ion chromatography (IC). For the determination of total sulphur content in the lignin, two methods were used; Schöniger combustion followed by ion chromatography (IC) and wet digestion followed by inductively coupled plasma (ICP). The elemental sulphur content in water-extracted lignin was determined after n-pentane extraction. ICP analysis was performed on the washed lignin. Calcium present in the lignin may bind polysulphides and thus be a source of the observed sulphur. The lignin was thus ion-exchanged to remove any calcium. To further investigate how the sulphur content in lignin can be decreased, two different types of reactions were performed on lignin; oxidation and reduction. The oxidation reactions were made in sodium hydroxide with oxygen at different temperatures and time on both original and water-extracted lignin. The reduction reactions were made on water-extracted lignin with Raney nickel in three different solvent systems: methanol: water, acetone: water and sodium hydroxide.   The original lignin contained 2.6% sulphur as determined by ICP. Washing lowered the content to 1.85% sulphur. By n-pentane extraction the elemental sulphur was lowered to a level of 1.82% sulphur, which was considered to be organically bound sulphur. Neither the ion exchange nor the oxidation lowered the sulphur content significantly.   The reduction reactions successfully the organically bound sulphur from 1.82% to a level of 0.54%.   The relative distribution of the sulphur content in the studied softwood lignin was as follows: about 29% as inorganic sulphur, about 1% as elemental sulphur and approximately 70% as organically bound sulphur, of which 49% could be removed by Raney nickel.
14

Existência, multiplicidade e concentração de sólitons para uma classe de problemas quaselineares. / Existence, multiplicity and concentration of solitons for a class of quaseline problems

SANTOS, Alan Carlos Baia dos. 10 August 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-08-10T17:08:26Z No. of bitstreams: 1 ALAN CARLOS BAIA DOS SANTOS - DISSERTAÇÃO PPGMAT 2015..pdf: 514416 bytes, checksum: d8457c84d59d8f7ec7033999105c2f07 (MD5) / Made available in DSpace on 2018-08-10T17:08:26Z (GMT). No. of bitstreams: 1 ALAN CARLOS BAIA DOS SANTOS - DISSERTAÇÃO PPGMAT 2015..pdf: 514416 bytes, checksum: d8457c84d59d8f7ec7033999105c2f07 (MD5) Previous issue date: 2015-02 / CNPq / Para ler o resumo deste trabalho recomendamos o download do arquivo, uma vez que o mesmo possui fórmulas e caracteres matemáticos que não foram possíveis trascreve-los aqui. / To read the summary of this work we recommend downloading the file, since it has formulas and mathematical characters that were not possible to transcribe them here.
15

Otimização do uso de água em refinarias de petróleo. / Optimization of water use in oil refineries.

Michele Anze 26 April 2013 (has links)
As refinarias de petróleo utilizam grandes quantidades de água em seus processos e por isso são impelidas a desenvolver fortes programas de redução de seu consumo. O objetivo do presente estudo é a aplicação de metodologia de otimização em problemas de alocação ótima e reuso de água em refinaria de petróleo. Diferentemente dos enfoques tradicionais que buscam tratar os efluentes gerados para atender às legislações ambientais ou para algum tipo de reuso na planta, a metodologia utilizada avalia os processos que usam água, questionando as causas da geração do efluente. Essa abordagem envolve o levantamento de dados industriais, análise dos processos de produção, identificação de oportunidades para aplicar as estratégias de otimização da alocação de água: racionalização, reuso e/ou reciclagem do efluente e, em seguida, a otimização da rede de água. Visando obter uma rede de água que seja aplicável na indústria, desenvolveu-se um procedimento específico baseado em regras heurísticas que representam as restrições reais dos processos. Através deste procedimento, o consumo de água fresca atingido é próximo do valor ótimo encontrado na literatura. As redes de água geradas são simples, com poucas interconexões e, consequentemente, os investimentos necessários para implementação são menores. / Oil refineries consume a large amount of water in their processes and because of that they are urged to develop strong programs to reduce their water consumption. The aim of this study is to apply an water optimization methodology in an oil refinery. Unlike traditional approaches that only search for treating the effluents in order to meet environmental legislation or to reuse in the plant, this methodology evaluates the processes that use water, questioning the causes of the wastewater generation. This approach involves the industrial data collection, analysis of production processes, identification of opportunities to optimize water use: rationalization, reuse and/or recycling of the effluent and, lastly, the water network optimization. Looking for a water network that is applicable in the industry, in this study it was also developed a specific optimization procedure based on heuristic rules representing the constraints of the actual processes. Through this procedure, freshwater consumption was found to be close to that of the theories found in the literature. The water networks generated are simple, with few interconnections and, consequently, the investments required to implement them are small.
16

The Impact of Eliminating Extraneous Sound and Light on Students' Achievement: An Empirical Study

Mangipudy, Rajarajeswari Venkata Surya 27 July 2010 (has links)
The impact of eliminating extraneous sound and light on students’ achievement was investigated under four conditions: Light and Sound controlled, Sound Only controlled, Light Only controlled and neither Light nor Sound controlled. Group, age and gender were the control variables. Four randomly selected groups of high school freshmen students with different backgrounds were the participants in this study. Academic achievement was the dependent variable measured on a pretest, a posttest and a post-posttest, each separated by an interval of 15 days. ANOVA was used to test the various hypotheses related to the impact of eliminating sound and light on student learning. Independent sample T tests on the effect of gender indicated a significant effect while age was non- significant. Follow up analysis indicated that sound and light are not potential sources of extraneous load when tested individually.
17

Minimizing methods and related topics for twist maps and the n-body problem / ツイスト写像とn体問題に関する最小化法及び関連する話題

Kajihara, Yuika 23 January 2023 (has links)
京都大学 / 新制・課程博士 / 博士(情報学) / 甲第24328号 / 情博第812号 / 新制||情||137(附属図書館) / 京都大学大学院情報学研究科数理工学専攻 / (主査)准教授 柴山 允瑠, 教授 矢ヶ崎 一幸, 教授 山下 信雄, 教授 田口 智清 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM
18

SCHEDULING ROTARY INJECTION MOLDING MACHINE

Urs, Shravan B. R. January 2005 (has links)
No description available.
19

Využití hloubkového kypřiče při pěstování obilovin a řepky olejné

MICHEK, Aleš January 2019 (has links)
The diploma thesis deals with the comparison of two technologies for soil cultivation in winter rape and winter wheat growing in 2017 and 2018. The first technology is a conventional technology, or classic using plowing and the second one is a minimization technology, where plowing is replaced by loosening. The work is focused on the comparison of fuel consumption, investment and operating costs, exploitative indicators and machine work quality. Furthermore, the thesis is focused on the description of particular machines and the company of primary agricultural production, where the machine is used.
20

A Comparative Study of Automated Test Explorers

Gustavsson, Johan January 2015 (has links)
With modern computer systems becoming more and more complicated, theimportance of rigorous testing to ensure the quality of the product increases.This, however, means that the cost to perform tests also increases. In orderto address this problem, a lot of research has been conducted during thelast years to find a more automated way of testing software systems. Inthis thesis, different algorithms to automatically explore and test a systemhave been implemented and evaluated. In addition to this, a second setof algorithms have been implemented with the objective to isolate whichinteractions with the system were responsible for a failure. These algorithmswere also evaluated and compared against each other. In the first evaluationtwo explorers, which I called DeBruijn and LStarExplorer, were consideredsuperior to the other. The first used a DeBruijn sequence to brute forcea solution while the second used the L*-algorithm to build an FSM overthe system under test. This FSM could then be used to provide a moreaccurate description for when the failure occurred. The result from thesecond evaluation were two reducers which both tried to recreate a failureby first applying interactions performed just before the failure occurred. Ifthis was not successful, they tried interactions further and further away, untilthe failure was triggered. In addition to this, the thesis contains descriptionsabout the framework used to run the different strategies. / D ̊a v ̊ara moderna datasystem blir allt mer komplicerade,  ̈okar detta st ̈andigtbehovet av rigor ̈osa tester f ̈or att s ̈akerst ̈alla kvaliteten p ̊a den slutgiltiga pro-dukten. Det h ̈ar inneb ̈ar dock att kostnaden f ̈or att utf ̈ora testerna ocks ̊ao  ̈ kar. F ̈or att f ̈ors ̈oka hitta en l ̈osning p ̊a det h ̈ar problemet har forsknin-gen under senare tid arbetat med att ta fram automatiserade metoder atttesta mjukvarusystem. I den h ̈ar uppsatsen har olika algoritmer, f ̈or attutforska och testa ett system, implementerats och utv ̈arderats. D ̈arut ̈overhar ocks ̊a en grupp algoritmer implementerats som ska kunna isolera vilkainteraktioner med ett system som f ̊ar det att fallera.  ̈aven dessa algoritmerhar utv ̈arderats och testats mot varandra. Resultatet fr ̊an det f ̈orsta ex-perimentet var tv ̊a explorers, h ̈ar kallade DeBruijn och LStarExplorer, somvisade sig vara b ̈attre  ̈an de andra. Den f ̈orsta av dessa anv ̈ande en DeBruijn-sekvens f ̈or att hitta felen, medan den andra anv ̈ande en L*-algoritm f ̈or attbygga upp en FSM  ̈over systemet. Den h ̈ar FSM:en kunde sedan anv ̈andasf ̈or att mer precist beskriva n ̈ar felet uppstod. Resultatet fr ̊an det andraexperimentet var tv ̊a reducers, vilka b ̊ada f ̈ors ̈okte  ̊aterskapa fel genom attf ̈orst applicera interaktioner som ursprungligen utf ̈ordes percis innan feletuppstod. Om felet inte kunde  ̊aterskapas p ̊a detta s ̈att, fortsatte de medatt applicera interaktioner l ̈angre bort tills felet kunde  ̊aterskapas. Ut ̈overdetta inneh ̊aller uppsatsen ocks ̊a beskrivningar av ramverken som anv ̈andsf ̈or att k ̈ora de olika strategierna.

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