While computational chemistry methods have a wide range of applications within the set of traditional physical sciences, very little is being done in terms of expanding their usage into other areas of science where these methods can help clarify research questions. One such promising field is Forensic Science, where detailed, rapidly acquired sets of chemical data can help in decision-making at a crime scene. As part of an effort to create a database that fits these characteristics, the present work makes use of computational chemistry methods to increase the information readily available for the rapid identification and scheduling of drugs to the forensic scientist. Ab initio geometry optimizations, vibrational spectra calculations and ESI-MS fragmentation prediction of a group of common psychedelics are here presented. In addition, we describe an under development graphical user interface to perform ab initio calculations using the GAMESS software package in a more accessible manner. Results show that the set of theoretical techniques here utilized, closely approximate experimental data. Another aspect covered in this work is the implementation of a boiling point estimation method based on group contributions to generate chemical dispersion areas with the ALOHA software package. Once again, theoretical results showed to be in agreement with experimental boiling point values. A computer program written to facilitate the execution of the boiling point estimation method is also shown.

Over the past centuries, a number of process routes for extraction of metal values from an ore or other resources have been developed. These can generally be classifiedinto pyrometallurgical, hydrometallurgical or electrometallurgical routes. In the caseof the latter two processes, the reaction medium consists of liquid phase electrolytesthat can be aqueous, non-aqueous as well as molten salts. The present dissertationpresents the work carried out with two aspects of the above-mentioned electrolytes.First part is about the electrolyte solutions, which can be used in solvent extractionrelevant to many hydrometallurgical or chemical engineering processes; the secondpart is about the molten salts, which is often used in the electrometallurgical processesfor production of a variety of many kinds of metals or alloys, especially those that arehighly reactive.In the first part of this thesis, the focus is given to the thermodynamics ofelectrolyte solutions. Since the non-ideality of high concentration solution is not wellsolved, a modified three-characteristic-parameter correlation model is proposed,which can calculate the thermodynamic properties of high concentration electrolytesolutions accurately. Model parameters for hundreds of systems are obtained foraqueous as well as non-aqueous solutions. Moreover, a new predictive method tocalculate the freezing point depression, boiling point elevation and vaporizationenthalpy of electrolyte solutions is also proposed. This method has been shown to be agood first approximation for the prediction of these properties.In the second part, a process towards the extraction of metal values from slags,low-grade ores and other oxidic materials such as spent refractories using molten saltsis presented. Firstly, this process is developed for the recovery of Cr, Fe values fromEAF slag as well as chromite ore by using NaCl-KCl salt mixtures in the laboratoryscale. The slags were allowed to react with molten salt mixtures. This extraction stepwas found to be very encouraging in the case of Cr and Fe present in the slags. Byelectrolysis of the molten salt phase, Fe-Cr alloy was found to be deposited on thecathode surface. The method is expected to be applicable even in the case of V, Mnand Mo in the waste slags.Secondly, this process was extended to the extraction of copper/iron from copperore including oxidic and sulfide ores under controlled oxygen partial pressures.Copper or Cu/Fe mixtures could be found on the cathode surface along with theemission of elemental sulphur that was condensed in the cooler regions of the reactor.Thus, the new process offers a potential environmentally friendly process routereducing SO2 emissions.Furthermore, the cyclic voltammetric studies of metal ions(Cr, Fe, Cu, Mg, Mn)in (CaCl2-)NaCl-KCl salt melt were performed to understand the mechanisms, such asthe deposition potential, electrode reactions and diffusion coefficients, etc. In addition,another method using a direct electro-deoxidation concept(FFC Cambridge method),was also investigated for the electrolysis of copper sulfide. Sintered solid porouspellets of copper sulfide Cu2S and Cu2S/FeS were electrolyzed to elemental Cu, S andCu, Fe, S respectively in molten CaCl2-NaCl at 800oC under the protection of Argongas. This direct electrolysis of the sulfide to copper with the emission of elementalsulfur also offers an attractive green process route for the treatment of copper ore. / QC 20100714

Orientadores: Rubens Maciel Filho, Maria Regina Wolf Maciel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T21:00:48Z (GMT). No. of bitstreams: 1 Lopes_MelinaSavioli_M.pdf: 732672 bytes, checksum: e13f0234f0e921262e228532b60abd4f (MD5) Previous issue date: 2008 / Resumo: O etanol perdido por evaporacao durante o processo de producao por fermentação pode ser recuperado por uma coluna de absorcao, a qual requer um sistema de controle robusto de acordo com sua complexidade. Este equipamento tambem e utilizado no tratamento do CO2, um co-produto deste processo. Neste sentido, no presente trabalho foi proposto e testado, o emprego de controladores feedforward-feedback, baseados em modelo inverso de redes neurais, os quais manipulam as vazoes de solvente que sao alimentados as colunas, para controlar a concentracao de etanol na corrente gasosa a saida da primeira coluna, e a concentracao de agua residual no efluente gasoso da segunda. Simulacoes foram feitas, sendo abordado tanto o problema regulatorio quanto o problema servo para as duas colunas de absorcao do processo estudado. O desempenho do controlador neural foi superior ao apresentado por um controlador convencional PID, para ambas as colunas de absorcao estudadas, pois o tempo de resposta, assim como o overshoot foi menor. A superioridade do controlador neural foi comprovada pelos valores obtidos para os parametros ITAE (integral do erro absoluto ponderada pelo tempo), IAE (integral do erro absoluto) e ISE (integral do quadrado do erro). Outro objetivo deste trabalho foi avaliar a influencia das incertezas nos sensores sobre o desempenho do sistema de controle. Foram testados tres niveis: 5, 10 e 15%, sendo as incertezas inseridas nas variaveis de entrada do tipo concentracao de etanol/agua residual na corrente gasosa. Para a coluna de recuperacao de etanol, tanto para o problema regulatorio quanto servo, nenhum controlador conseguiu estabilizar a variavel controlada no set point, no entanto, quando empregado o controlador neural a amplitude da faixa de oscilacao da variavel controlada foi menor para todos os niveis de incerteza testados. Já para a coluna de tratamento de CO2, os controladores encontraram dificuldades em manter a estabilidade do sistema. Neste sentido, o controlador neural apresentou um desempenho satisfatorio para incertezas de 5 e 10%, enquanto que o PID nao conseguiu manter o sistema estavel para incertezas superiores a 5%. Com base nos testes realizados foi constatado que o controlador neural proposto constitui uma opcao atrativa para o controle das colunas de absorcao do processo deproducao de etanol por fermentacao, principalmente quando os niveis de incerteza forem de ate 10%. / Abstract: Some of ethanol lost by evaporation during its fermentation production process may be recovered using an absorption column, which requires a robust control system. This equipment also is used on carbonic gas treatment, a by-product of this process. In the present work, the development of nonlinear feedforward-feedback controllers, based on a neural network inverse model, was proposed and tested to manipulate the absorbent flow rates in order to control the residual ethanol concentration in the effluent gas phase at the first absorption column, and the residual water at the second one. Simulation studies were carried out for the regulator and servo problem, for both absorption columns studied. The neural controller proposed outperformed a conventional PID, because the response time, and also the overshoot were smaller when the neural controller was applied. The results were confirmed by the ITAE (integral of time multiplied by the absolute error), IAE (integral of absolute error) and ISE (integral of square error) parameters. The measurement uncertainties influence on control system performance was tested for three levels: 5, 10 and 15%. The uncertainties were introduced on ethanol/residual water concentration on gas phase. For the ethanol recovery column, neither PID nor the neural controller drove the controlled variable exactly to the set point, however, the neural controller provided a smaller oscillation for all uncertainty levels tested, for regulator and servo problem. The neural controller also outperformed PID in CO2 treatment column. For the regulator and servo problems the neural controller successfully proceeded when the uncertainty level was 5% or 10%, while the PID did not deal adequately with uncertainties above 5%. Therefore, the proposed neural controller proved be an attractive control solution for the absorption columns of ethanol production process by fermentation, especially when the input variables carry small uncertainties ( less than 10%) from the sensors. / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientadores: Maria Regina Wolf Maciel, Rubens Maciel Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-12T09:05:16Z (GMT). No. of bitstreams: 1 Rocha_RodrigoSantos_M.pdf: 2841011 bytes, checksum: 57c5b6eb64b6d9ff9403fac6e1fd2f8d (MD5) Previous issue date: 2008 / Resumo: A curva PEV é uma importante ferramenta que define os rendimentos de diversos derivados de petróleo obtidos em função dos seus pontos de ebulição verdadeiros, fornecendo informações importantes para decisões referentes ao controle dos processos de refinarias e sobre a qualidade do petróleo produzido. A curva PEV está bem estabelecida para pontos de ebulição de até 565?C, através de métodos estabelecidos pela ASTM. O emprego de uma metodologia para a caracterização das frações pesadas de petróleo com pontos de ebulição acima de 565?C e o desenvolvimento de um procedimento para a extensão da curva PEV nessa faixa tem, portanto, um impacto decisivo no melhor aproveitamento do óleo cru nacional, já que estes têm uma quantidade expressiva de frações pesadas na sua composição. Para se ter um conjunto de dados da curva PEV mais abrangente para esses petróleos, foi estabelecida uma metodologia para a extensão da curva PEV através da destilação molecular. O objetivo geral deste trabalho foi determinar experimentalmente a extensão da curva PEV de frações pesadas de petróleos nacionais, utilizando o processo de destilação molecular. Desse modo, a extensão da curva PEV foi feita a partir da obtenção dos dados do destilador molecular para dois tipos de petróleos ainda não estudados pelo grupo do LDPS/UNICAMP e, através da correlação DESTMOL, as temperaturas de operação do destilador molecular foram convertidas para os pontos de ebulição verdadeiros correspondentes. Por meio desse processo, as correntes de produto obtidas foram quantificadas e avaliadas através de caracterizações físico-químicas. A metodologia através da destilação molecular atingiu valores de PEV próximos a 700?C, proporcionando, além disso, ganhos consideráveis de destilado, representando grandes avanços na área. / Abstract: The TBP curve is an important tool that defines the yield of petroleum products in function of its true boiling points, supplying important information for decisions of refinery process control and quality of the produced oil. The TBP curve is well established for true boiling points up to 565?C, through established methods for the American Society and Testing Materials (ASTM). The use of a methodology for the characterization of heavy petroleum fractions with true boiling points above 565?C and the development of a procedure for the extension of TBP curve in this range has, therefore, a decisive impact to the best improvement of national crude oil, since they have an expressive amount of heavy fractions in its composition. To improve this data set of TBP curve for heavy oils, a methodology for the extension of TBP curve was established through the molecular distillation. The general objective of this work was to determine experimentally the extension of TBP curve for national heavy petroleum fractions, using the molecular distillation process. In this manner, the extension of TBP curve was made from the data attainment of molecular distiller for two types of oils not still studied for the LDPS/UNICAMP group and, through the application of DESTMOL correlation, the operating temperatures of the molecular distiller was converted for the corresponding true boiling points. In this process, the product streams were quantified and evaluated through physical-chemical characterizations. The methodology using molecular distillation reached TBP values up to 700?C, providing, so, considerable gain of distilled, representing a notable advance in this area. / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

The factors determining the quality of surface mount technology (SMT) solder joints are numerous, and complex. The exploration of these factors, and how they may affect the reliability and quality of the joints can only be achieved through continuous research. In this project, essential areas of SMT joints were selected for study and analysis, with the intention of providing additional design and process guidelines for the production of quality SMT joints. In the infrared reflow process, one of the common defect phenomena is the occurrence of tombstoning; that is after soldering only one end of the component is soldered while the other is lifted up, assuming a position like a tombstone. The initiation of tombstoning during reflow was analysed based on the forces acting on the component. A model was developed to predict the initiation of this phenomenon. The model shows that, under vibration-free conditions, the surface tension of the molten solder is the source of the force causing the initiation of tombstoning. The contact angle, which varies with the length of the printed circuit board solder land, has a significant effect on the value of the surface tension acting as a force pulling upward on the component. The model further shows that tombstoning initiation is due to the combined effects of the surface tension; the weight of the component; the dimensions of the component; the length of the solder underneath the component; and the length of the solder protruding from the end of the component. Selected components were used as examples for predicting the conditions of initiation, and these conditions were further substantiated by a series of experiments. Another area of study was a method which directly pulled the components off printed circuit boards and this was used as a means for testing the bond quality of surface mount technology leadless chip solder joints. Components D7243, CC1206, RC1206, RC121O, and CC1 812 were selected for this study. It was found that the ultimate tensile force which breaks a component off the printed circuit board has the potential to be used as a parameter for measuring the quality of the solder joint. The effect of solder thickness on the strength of a joint has also been investigated. The shape of joints soldered by two methods, wave soldering and infrared reflow, were compared. Joints at the two ends of a component produced by infrared reflow were found more uniform than the ones produced by wave soldering. A recommendation is made here for the wave soldering approach in achieving uniform solder joints. The effects of solder shape on the joint strength were further investigated by finite element analysis. A convex joint was found marginally more robust than a concave joint. Two aspects of the internal structure of SMT solder joints were investigated, void content and copper/tin intermetallic compounds. The voiding conditions of wave-soldered and infrared reflow joints were compared. No voids were found in all specimens that were produced by wave soldering. However, there were always voids inside joints produced by infrared reflow. Microhardness tests indicated that the hardness of compounds at the copper/solder interface of infrared reflowed joints is lower than that in the wave-soldered joints. It is considered that the lower hardness of the interfacial region of the infrared reflowed joints is due to the presence of voids. Scanning electron microscopy was used to study the formation of copper/tin intermetallic compounds for joints produced by infrared reflow. The results show that Cu 6 Sn5 was the only compound with a detectable thickness. Other compounds such as Cu3 Sn, were virtually not found at all. Aging of the joints at 100°C, shows that both the Cu 6Sn5 and the overall interfacial thickness grew with time. One of the important areas which had been overlooked previously and was studied in some details was the effects of solder paste exposure on the quality of solder paste. The characteristic changes of solder paste due to exposure were investigated in three areas, weight loss, tackiness, and rheology. The evaporation of low boiling point solvents was considered as the main contribution to the loss in the weight of the solder paste. The weight loss against exposure time was found to follow an exponential behaviour. A method was designed to evaluate the tackiness changes of solder paste due to exposure. It was found that the decay of tackiness against exposure time can be expressed by a power law. It is recommended that solder paste manufacturers should provide the necessary characteristic constants so as to enable the characteristics to be calculated after a specific exposure. The rheological changes of the solder paste as a result of exposure were also investigated. The implication on the printability of the solder paste due to these changes was studied and discussed.

<p> Water drops at their boiling point were projected through a steam atmosphere to strike a surface which was varied in temperature from 300 to 900 degrees Fahrenheit. A high-speed motion picture study of the collision process showed that, except at low surface temperatures, the drop flattened out on impact and rebounded in a state of oscillation. Measurements of the change in drop diameter on collision indicated that the amount of evaporation due to heat transfer from the surface was extremely small except when the drop extensively wetted the surface. Solution of a mathematical model of the initial impact dynamics and models of heat transfer through a vapour film beneath the drop and by direct liquid-surface contact confirmed experimental observations. </p> / Thesis / Doctor of Philosophy (PhD)

No / Modelling played an important role in simulation, optimisation, and control of multi-stage flash (MSF) desalination processes. Top brine temperature (TBT) is one of the many important parameters that affect optimal design and operation of MSF processes. Within the MSF process model, calculation of TBT is therefore important. For a given pressure, TBT is a function of boiling point temperature (BPT) at zero salinity and temperature elevation (TE) due to salinity. In this work, we develop several neural network (NN) based correlations for predicting TE. It is found that the NN based correlations can predict the experimental TE very closely. Also predictions by the NN based correlations were good when TE values, obtained using existing correlations from the literature are compared. Due to advancement of the microcomputer, plant automation becomes reliable means of plant maintenance. NN based correlations (models) can be updated in terms of new sets of weights and biases for the same architecture or for a new architecture reliably with new plant data.

Purpose To investigate the possibility to reduce the number of failures caused by moisture and dust ingress in lighting equipment by looking towards customer acceptance and warranty claims, and then translate the result to technical attributes. Methodology The methodology is set up to be a part of a Design for Six Sigma project including the steps up to Concept development and business/customer approval. Known product development tools are used to evaluate existing techniques and generate new concepts. Customer analysis is done by surveys and investigating warranty claims. Result &amp; Conclusions The customer analysis in this thesis show that Brazil and to some extent UK is the countries where the problem is seen as most severe. It also shows that complaints regarding dust are far more common than complaints regarding moisture when it comes to lamps placed at the lower part at the front of the truck. When the results from the customer analysis are compared with the technical aspects it shows that the most beneficial way to deal with the problem is to create a good air flow while still keeping the pore size, which could be done by using membranes and the help from CFD (Computational Fluid Dynamics) simulations. Trapping solutions are also welcomed by the customer as long as they can be part of the regular service. / Syfte Att undersöka behov och möjligheter att reducera problem med fukt och damminträngning i exteriöra belysningsartiklar på lastbilar genom att titta på kundacceptans och garantiärenden samt översätta detta till tekniska attribut. Metod Arbetet är upplagt som en del av ett Design for Six Sigma-projekt och innefattar stegen fram till Concept development and business/customer approval. Kända produktutvecklingsverktyg används för att ta fram underlag till konceptgenerering. Kundanalys utförs med hjälp av enkäter och undersökningar av garantiärenden. Resultat &amp; slutsats Kundanalysen i denna examensrapport visar att Brasilien och Storbritannien är de länder där problemet uppfattas som störst. Den visar också att klagomål gällande damm är mycket vanligare än klagomål gällande fukt när det gäller lyktor placerade i den nedre delen i fronten på lastbilen. När resultaten från kundanalysen jämförs med de tekniska aspekterna finner man att det mest gynnsamma sättet att ta sig an problemet är att försöka få bra ett bra luftflöde i lyktorna men samtidigt minimera porstorleken. Detta kan man åstadkomma med hjälp av membran och CFD (Computational Fluid Dynamics) simuleringar. Lösningar som handlar om att fånga upp dammet och fukten accepteras också av kunden så länge som detta kan lösas med hjälp av den vanliga servicen.

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In the reservoir conditions, a petroleum fluid is defined by its thermodynamic and volumetric properties and by its physicochemical properties. Their behaviors are modeled from experimental data in order to properly simulate the processing of these fluids during the production.   With the advent of new regulations and rigidity that exist at the custom regulations today, research centers have great difficulty in obtaining large amounts of samples. For these reason, although there are several methods to characterize the different components of crude oil, the laboratories are turning increasingly to techniques that requires lower amounts of samples: micro-distillation, gas chromatography (GC).   The micro-distillation is a fast and completely computerized technique made to substitute the standard distillation for analysis of liquid petroleum products. Advantages of the method compared to the standard distillation are the reduction of working time by at least a factor of 4, the small sample volumes required for distillation (few micro liters). [24]   This report is aimed to create a simple model that can predict yield curves of physical distillation, without using the micro-distillation technique. The results obtained through gas chromatography (GC) analysis by laboratory technicians enable the modeling of the fluid behavior. Having identified and treated practically all aspects of micro-distillation through simulations with PRO/II, I found out that, regardless of the setting and the thermodynamic method used, there are always significant differences between simulation results and those of the micro-distillation.   The result shows that it’s still difficult to create a model which can replace micro-distillation and gas chromatography (GC) because of the huge gap between the simulation results and micro-distillation. Furthermore, the dynamics revealed that the micro distillation is not accurate. I had hoped to get additional results by studies the correlations with more samples, but that did not turn out to be the case. Regardless of that, I think that it would be interesting to study more samples and use another simulator to properly represent micro distillation. This could be an interesting topic for further studies. / Under de föhållanden som reservoarens miljö erbjuder, definieras en petroleumvätska av dess termodynamiska och volymetriska egenskaper och av dess fysikalisk-kemiska egenskaper. För att korrekt simulera bearbetningen av dessa vätskor under produktion, deras beteende modelleras från experimentella data Med tillkomsten av nya regler och oflexibilitet som finns på tullbestämmelser vid gränserna idag, har forskningscenter stora svårigheter att få större mängder prover levererade. Av den anledningen, trots att det finns flera metoder för att karakterisera de olika komponenterna av råolja, tvingas laboratorier att vända sig mer och mer till alternativa analysmetoder som kräver mindre provvolymer: mikrodestillation, gaskromatografi, etc.   Mikrodestillation, som är en snabb och helt datoriserad teknik, visar sig kunna ersätta standarddestillation för analys av flytande petroleumprodukter. Fördelar med metoden jämfört med standarddestillering är minskad arbetstidsåtgång med minst en faktor 4. Därtill krävs endast en begränsad provvolym (några mikroliter) i jämförelse med standarddestillation.  [24]   Denna rapport syftar till att skapa en enkel modell som kan förutsäga avkastningskurvan av fysisk destillation, utan att använda mikrodestillationsteknik. De resultat som erhölls genom gaskromatografiska analyser möjliggjorde modelleringen av det vätskebeteendet hos det analyserade provet. Efter att ha identifierat och behandlat praktiskt taget alla viktiga aspekter av mikro destillation genom simuleringar med PRO/II, fann jag att, oberoende av inställningen och den termodynamiska metod som används,  det alltid finns stora skillnader mellan simulering och mikro destillation.   Resultatet visar att det fortfarande är svårt att skapa en modell som kan ersätta mikrodestillering och gaskromatografi på grund av differensen mellan simuleringsresultaten å ena sidan, och resultaten från mikrodestillering å andra sidan. Dessutom visade resultaten att mikrodestillation som analysmetod inte ger tillförlitliga resultat. Min förhoppning var att få ytterligare användbara resultat genom att studerar potentiella korrelationer emellan fler prover, men detta visade sig inte vara fallet. Jag anser att det skulle vara intressant att studera fler prover och använda en annan simulator för att bättre representera mikrodestillation. Detta skulle kunna vara ett intressant ämne för vidare studier.