This thesis presents investigations into the design and synthesis of nanomaterials in supercritical carbon dioxide (sc-CO₂) as well as novel experimental design methodologies. First, the process-structure-property relationships are studied for the deposition of materials from organometallic precursors in sc-CO₂. The materials that were investigated in these studies were: (1) the semiconductor material copper zinc tin sulfide (Cu₂ZnSnS₄, or CZTS), which has application in solar energy capture; (2) zinc sulfide nanoparticles deposited onto carbon nanotubes, which have application in optoelectronics; and (3) silver nanoparticles deposited on silicon and glass wafer surfaces, which find application as biosensors via surface enhanced Raman spectroscopy. Next, two novel experimental design methodologies were implemented. The first is termed layers of experiment with adaptive combined design (LoE/ACD), which efficiently optimizes a process that is expensive and time consuming to study by zooming in on the process optimum through successive layers. The mean silver nanoparticle size was optimized as a function of temperature in the sc-CO₂ system using the LoE/ACD approach. The second experimental design methodology is called initial experimental design (IED). The IED methodology was developed to choose the first round of experiments for a system that is expensive to study (in terms of time and money), poorly understood, and possesses a related, non-identical system that is well-studied. The IED approach was used to optimize the mean iridium nanoparticle size as a function of temperature given expert opinion, prior data, and an engineering model for silver nanoparticles synthesized in sc-CO₂.

The purpose of this work is to provide simulation-based support for making optimal (or near-optimal) decisions in situations where decision makers are faced with imperfect information. We develop several novel techniques and algorithms for simulation-based optimization and decision support and apply them to two categories of problems: (i) Unmanned Aerial Vehicle (UAV) path planning in search operations, and; (ii) optimization of business process models. Common features of these two problems for which analytical approaches are not available, are the presence of imperfect information and their inherent complexity. In the UAV path planning problem, the objective is to define the path of a UAV searching for a target on a known road network. It is assumed that the target is moving toward a goal and we have some uncertain information about the start point of the target, its velocity, and the final goal of the target. The target does not take evasive action to avoid being detected. The UAV is equipped with a sensor, which may detect the target once it is in the sensor’s scope. Nevertheless, the detection process is uncertain and the sensor is subject to both false-positive and false-negative errors. We propose three different solutions, two of which are simulation-based. The most promising solution is an on-line simulation-based method that estimates the location of the target by using a Sequential Monte Carlo (SMC) method. During the entire mission, different UAV paths are simulated and the one is chosen that most reduces the uncertainty about the location of the target. In the optimization of the business process models, several different but related problems are addressed: (i) we define a measure of performance for a business process model based on the value added by agents (employees) to the process; (ii) we use this model for optimization of the business process models. Different types of processes are distinguished and methods for finding the optimal or near-optimal solutions are provided; (iii) we propose a model for estimating the performance of collaborative agents. This model is used to solve a class of Assignment Problems (AP), where tasks are assigned to collaborative agents; (iv) we propose a model for team activity and the performance of a team of agents. We introduce different collaboration strategies between agents and a negotiation algorithm for resolving conflicts between agents. We compare the effect of different strategies on the output of the team. Most of the studied cases are complex problems for which no analytical solution is available. Simulation methods are successfully applied to these problems. They are shown to be more general than analytical models for handling uncertainty since they usually have fewer assumptions and impose no restrictions on the probability distributions involved. Our investigation confirms that simulation is a powerful tool for providing decision-making support. Moreover, our proposed algorithms and methods in the accompanying articles contribute to providing support for making optimal and in some cases near-optimal decisions: (i) our tests of the UAV simulation-based search methods on a simulator show that the on-line simulation method has generally a high performance and detects the target in a reasonable time. The performance of this method was compared with the detection time when the UAV had the exact information about the initial location of the target, its velocity, and its path (minimum detection time). This comparison indicated that the online simulation method in many cases achieved a near-optimal performance in the studied scenario; (ii) our business process optimization framework combines simulation with the Hungarian method and finds the optimal solution for all cases where the assignment of tasks does not change the workflow of the process. For the most general cases, where the assignment of tasks may change the workflow, we propose an algorithm that finds near-optimal solutions. In this algorithm, simulation, which deals with the uncertainty in the process, is combined with the Hungarian method and hill-climbing heuristics. In the study of assigning tasks to collaborative agents we suggest a Genetic Algorithm (GA) that finds near-optimal solutions with a high degree of accuracy, stability, scalability and robustness. While investigating the effect of different agent strategies on the output of a team, we find that the output of a team is near-optimal, when agents choose a collaboration strategy that follows the principle of least effort (Zipf’s law) and use our suggested algorithm for negotiation and resolving conflicts. / QC 20111202

Abstract For the past few years, electronics manufacturing may have been the victim of its own success. Unlike in heavier industries, rationalization is a concept that was unknown in the sector until only a few years ago and even now, many companies are struggling with cost-cutting measures. Production systems in electronics manufacturing need to be highly flexible because of a varying and evolving environment. Therefore real-time process control and, possibly as a result, production optimization are extremely challenging areas. Traditional approaches often do not work due to a lack of robustness or reliability. For this reason, a new generation of decision support systems is needed in response to some specific problems. The thesis addresses topics such as design of intelligent interfaces for knowledge acquisition and elicitation, use of that knowledge for improved data analysis and diagnostics, real-time feedback control, self-tuning capabilities, and evaluation of optimization methods in discrete processes. Topics covered therefore include the whole scope of a decision support system, from its design through to the evaluation of its performance as well as interaction capabilities as a vehicle for sharing information. The aim of this research is to streamline the development of a new generation of decision support systems by providing tools and methods for a better integration of knowledge in an evolving environment. The main interest lies not only in improved data analysis, but also in better formalization and use of diagnosis. Case studies presented in this thesis demonstrate the practical feasibility of such an approach.

Background: When a potential customer reaches out to NKT and requests themto tender an offer for a project, NKT will start to compile the information neededfor the customer to make an informed decision. Among others, one document thatis included in the information is a CSO. This drawing displays an overview of thecomplete cable installation, which makes it easy for the customer to see all compo-nents included in the installation. Up until the project, the process of building a CSO has been time-consuming and lacked a standardized workflow. This has causedinconsistencies in deliveries to customers and, if requested, the process of makingchanges has been a time-consuming challenge. Objectives: The objective of this project was to find a way to optimize by standard-izing the way the engineers work today by implementing a new production processwhen building CSOs and creating drawings. Methods: This project was conducted using the PDCA method as it provides struc-ture during the stages of the project and allows for iterative project cycles. A com-prehensive literature study was performed to learn about ways to optimize and stan-dardize workflows. Semi-structured open-ended interviews were held with affectedpersonnel to build a complete image of the cause of the issues with the current solu-tion. The CAD software SolidWorks was used as a tool to create the new solution asits integrated features provided the possibility to automate a big part of the process. Results: The interviews helped gain valuable insight into what parts of the current so-lution have proved to be problematic. The responses varied between the participants,but the common denominators were that the lack of automation and standardizationcaused much frustration. The engineers were asked to time themselves using boththe old and new production process when creating the same projects. The resultsshowed that the new process allowed them to build the same CSO with an averagetime saving of 85%. Conclusions: The results show that, even though the new process still needs workto be a full replacement for the old solution, it has the potential to bring big timesavings to the engineers that work with the CSO. A standardized workflow will helpto deliver more consistent designs to customers

Oxidative coupling of methane (OCM) is a promising route for converting abundant natural gas resources into more useful chemicals like paraffins and olefins (primarily C2). However, to date, there is no current OCM production plant due to low overall conversion and selectivity to the desired product(s). In this work, different operating factors are studied experimentally and through simulation with respect mainly to three responses: CH4 conversion, C2 main product selectivity, and COx side product selectivity. The aim is to identify the best operating condition for maximum ethylene production combined with COx production. Design of experiments (DoE) method was used to analyze the experimental results by applying the full factorial approach. Simulation results were studied by finding the correlation strength between input factors and responses. It was found that the performance of an OCM reactor could be greatly improved under optimal operating conditions. Operating temperature and CH4/O2 ratio have the highest influence while catalyst weight and flow rate have the lowest influence on the OCM responses and mainly depend on rector dimensions.

The key objectives of this research were to develop an integrated design and analysis methodology for sheet-metal product development based on agent-based technology, feature-based design, optimization and finite element analysis techniques, and to study the performance of prototype systems developed based on such a methodology. To achieve the research objectives, an agent-based framework was proposed for integrating and coordinating activities of participants involved in sheet-metal product development based on the investigation of the industrial requirements and the procedures of the development of sheet-metal products. Prototype systems were developed based on the proposed framework to answer research problems outlined for the design and implementation of agent-based systems, such as agent encapsulation, system architecture, agent communication and agent coordination. The performance of such prototype systems demonstrates that communication and coordination among domain agents can facilitate product development and reduce product cost. An agent-based optimization approach based on an "A-Teams" approach (Talukdar et al, 1996) was proposed for process optimization in the tooling design stage to combine the utilization of the traditional optimization techniques used to solve sheet-metal forming problems and agent-based approaches. Three test cases were used of varying complexity from a rectangular cup to the NUMISHEET'99 automobile front door panel simulation benchmark for the determination of optimal drawbead restraining forces and blankholder forces when designing draw dies for stamped parts. A network of software agents, each implementing a different numerical optimization technique, was used in combination with metal forming simulation software to optimize process variables. It was found that the performance of each agent (and optimization technique) depended strongly on the complexity of the problem. For a given amount of computational effort, a network of collaborating agents using different optimization techniques always outperformed agents using a single technique in terms of both the best solution found and the variance of the collection of best solutions. To provide guidance for the design and implementation of real applications, static and dynamic attributes and metrics of such agent-based collaborative systems, which can be evaluated in the preliminary system design stage and the system implementation stage, were proposed to study the impact of system architectures and coordination strategies on system performance. In addition, real-time system performance was statistically studied based on the data collected by the visualiser agent generated with the agent building toolkit. The results of case studies for system performance evaluation demonstrate the applicability of evaluation strategies proposed and can be used as a reference model for performance and scalability analysis on agent-based sheet-metal product development systems. The proposed evaluation strategies are applicable to general applications for product development by taking into consideration other performance indicators. / Thesis / Doctor of Philosophy (PhD)

<p>Chile and Santiago are struggling with heavy environmental problems as a consequence of urbanisation and industrialisation. In the Santiago region the air is seriously contaminated and most of the rivers are classified as heavily polluted.</p><p>The aim of this thesis is to survey the industrial fluid waste situation in the Santiago region and to make suggestions on technological improvements or process changes. The purpose is also to study five different enterprises more closely and to give more detailed suggestions for improvement. Another purpose is to summarize relevant Chilean legislation.</p><p>Information, provided by the supervisory authority, about the release of industrial wastewater to rivers has been analysed. Deep interviews have been made with authorities and consultants. Five enterprises have been visited; a brewery, a dairy, a bakery, a producer of cooked meat and a surface treatment industry. The present treatment of the wastewater was studied at the plants and the information was completed with a questionnaire to the responsible at each company.</p><p>The contamination load released to the Chilean rivers is heavy. The rivers in southern Chile receive the biggest loads of BOD and SS and the rivers in central Chile were the most exposed to discharges of the metals Cr, Cu, Zn and CN as well as phenols.</p><p>The industrial discharge into the rivers of Santiago RM and Region VII is also to a large extent characterized by high concentrations of BOD and SS. Large releases of oils and greases, nitrogen and phosphorus are also fairly common, as are too high or too low pH levels. The food industry is the most contaminating sector, but also tanneries have great problems with effluents exceeding limits.</p><p>All five companies visited share the need to take measures towards more water saving technologies. The brewery, the producer of cooked meat and the surface treatment company also need end-of-pipe-treatment of their wastewater. In many cases, the recommended and most economic alternative is to separate the flows with the highest concentration of polluting substances for internal treatment, while releasing the rest of the wastewater to the outside sewage system. The costs of the suggested changes must be balanced against the present costs for treatment of wastewater and remaining solid waste as well as the costs for alternative treatments.</p><p>The economic incentives for Chilean companies to invest in wastewater treatment plants or to optimize the processes until today have been few. Cost reductions may be achieved by savings in water consumption and reuse of raw material. Another motive could be to keep “one step ahead” if the discharge limits in the future are tightened up leading to rising costs.</p> / <p>Chile och Santiago brottas med omfattande miljöproblem till följd av urbanisering och industrialisering. I santiagoregionen är luftföroreningarna svåra och de flesta floderna klassas som gravt förorenade av CONAMA, det chilenska naturvårdsverket.</p><p>Syftet med examensarbetet är att kartlägga situationen i santiagoregionen med avseende på industriell avloppsrening samt att ge förslag på förbättring av teknik eller förändring av processer. Dessutom är syftet att studera fem industrier närmare och att ge mer detaljerade förslag på åtgärder. Syftet är också att ge rekommendationer för fortsatt utveckling av relevant chilensk lagstiftning.</p><p>Uppgifter från tillsynsmyndigheten för utsläpp till ytvattendrag har studerats och djupintervjuer har gjorts med myndigheter och konsulter. Fem olika industrier besöktes; ett bryggeri, ett mejeri, ett bageri, ett charkuteri samt en ytbehandlingsindustri. Nuvarande hantering av processvattnet studerades på plats och med hjälp av ett frågeformulär kompletterades uppgifterna av ansvariga på företagen.</p><p>Föroreningsbelastningen på Chiles floder är stor. Floderna i södra delen av landet tar emot störst mängder organiskt material och suspenderat material medan centrala Chiles floder är värst drabbade av utsläpp av metallerna Cr, Cu, Zn och CN samt utsläpp av fenoler. Utsläppen från industrin till floderna i Region Metropolitana och Region VII kännetecknas också i stor utsträckning av höga halter BOD och suspenderat material. Relativt vanligt är också stora utsläpp av oljor och fetter, kväve, fosfor samt för höga eller låga för pH-värden. Det är främst flera olika typer av livsmedelsindustri, som har de största utsläppen till floderna, men även garverierna har stora problem med överskridande av gränsvärden.</p><p>Gemensamt för de fem besökta företagen är att vattenbesparande åtgärder bör vidtas för att minska volymen avloppsvatten som går till extern eller intern behandling. Bryggeriet, charkuterifabriken och ytbehandlaren behöver även end-of-pipe-rening. Det kan ofta vara lämpligt och mer ekonomiskt att avskilja de flöden som har högst halt av föroreningar till den interna reningsanläggningen. Resten av avloppet kan i vissa fall släppas ut på avloppsnätet. Kostnader för föreslagna åtgärder måste vägas mot aktuella kostnader för behandling av avlopp och restprodukter, samt kostnader för alternativa behandlingar.</p><p>Incitamenten, bl a de ekonomiska, för chilenska företag att skaffa eget reningsverk eller att resurseffektivisera produktionen har hittills varit små. Kostnadsminskningar kan uppnås genom sänkt vattenförbrukning samt återanvändning av råmaterial. Ytterligare en drivkraft kan vara att ”ligga steget före” om utsläppskraven i framtiden skärps och kostnaderna därmed ökar.</p>

Studien som har genomförts utgör en analys av vad byggentreprenörer värdesätter hos underentreprenörer i processen från utlysning till utfört arbete. Syftet med studien är att genom intervjuer av byggentreprenörer få kunskap om vad de värdesätter hos underentreprenörer under hela processen. På så sätt kan underentreprenörer få vetskap om förbättringsmöjligheter i processen. En kvalitativ undersökning har genomförts i vilken sekundärdata har samlats in genom vetenskapliga artiklar och böcker och primärdata har samlats in genom intervjuer med åtta byggentreprenörer. En semistrukturerad intervjumall har tagits fram där intervjuarna kan ställa följdfrågor och intervjupersonerna får möjlighet att reflektera. Intervjumallen är utformad utifrån studiens syfte och fakta avseende byggindustrins marknad som har samlats in genom vetenskapliga artiklar. Intervjuerna har påvisat olika faktorer och aktiviteter som är värdeskapande i processen. Då byggentreprenörer väljer vilka underentreprenörer de ska lämna anbudsförfrågan till är det främst relationen som är viktig. Relationen påverkas av personkemi och tidigare erfarenheter av samarbete och kvalitet. Vid hög konkurrens blir priset en viktigare faktor, då lämnar byggentreprenörer anbudsförfrågan till fler underentreprenörer för att få ett så lågt anbud som möjligt. Anbudet bör vara tydligt utformat där det framgår vad underentreprenören har räknat på. Många byggentreprenörer anser det värdeskapande att underentreprenörer utnyttjar den spetskompetens de besitter och kommer med förbättringsförslag i anbudet. Förslaget kan gynna alla parter i kedjan; beställare, byggentreprenör och underentreprenör. Då byggentreprenörer väljer vilken underentreprenör de ska anställa är priset alltid en betydande faktor. Dock är priset inte alltid avgörande. Hur samarbetet har fungerat i tidigare projekt kan vara minst lika viktigt, om inte viktigare. I produktionsfasen värdesätts kommunikation. Genom god kommunikation mellan inblandade parter kan missförstånd minskas och processer effektiviseras. På så sätt kan underentreprenörer leverera rätt kvalitet i rätt tid och till rätt pris. Engagemang, tillgänglighet, information och återkoppling är värdeskapande i hela processen. Genom att rapportera direkt vid förändringar kan hela projektet förbättras då onödiga kostnader kan undvikas. Vid avslut bör alla dokument lämnas in och utbildningar av hur installationen ska hanteras göras inom avsatt tid. / The purpose of the study is to find out what subcontractors can do to increase customer value in the process from announcement to delivered service. The customer in this study is the building contractor. By giving subcontractors the knowledge of how to improve their process, improvements for the construction industry in general can be made. The study is based on information from interviews with eight building contractors and information from scientific articles. Interviews have claimed that several factors and activities can create customer value. The relation between building- and subcontractors is a significant factor when building contractors choose who they will send an offer request to. In a competitive position the price is more important. In that case the building contractors will send out offer requests to a bigger number of subcontractors, to get the lowest bid possible. The bid should be clearly presented and show what is included. Most building contractors value when subcontractors exploit their expertise and propose improvements in the bid. The proposition could benefit all parties in the supply chain; the client, the building contractor and the subcontractor. The price is always a significant factor but interviews has claimed that it is not always crucial. Experiences of cooperation with the subcontractor in earlier project has proved to be as important. In production communication is important. Through good communication between all parties in a project misunderstandings can be reduced and processes improved. Commitment, accessibility, information and feedback are factors that is important through the entire process from announcement to delivered service. By reporting directly to any changes, the entire project is improved and unnecessary costs can be avoided. Upon completion of a project all documents must be submitted in time.

O presente trabalho envolve a elaboração de um modelo matemático para um processo industrial de produção de cloro e soda a partir de salmoura, visando sua otimização em termos de eficiência de produção e dos custos dos consumos de energia elétrica e vapor. O estudo contemplou duas etapas do processo: eletrólise e concentração de licor de NaOH por evaporação. Para a unidade de eletrólise não foram encontrados na literatura modelos fenomenológicos adequados à simulação do processo. Por essa razão, foram desenvolvidos modelos empíricos baseados em redes neurais tipo ?feedforward? constituídas por três camadas, a partir de dados da operação industrial. Para a unidade de evaporação foi elaborado um balanço de energia adequado à estimativa do consumo de vapor. Porém, devido à falta de modelos para previsão das relações de equilíbrio para o sistema, o modelo fenomenológico foi substituído por um modelo de redes neurais tipo ?feedforward? de três camadas também para essa unidade. Para ajuste dos modelos, uma base de dados foi montada a partir de dados de operação do processo da Carbocloro S.A. Indústrias Químicas, localizada em Cubatão-SP, analisados por meio de técnicas estatísticas multivariadas, visando detectar e eliminar erros grosseiros e dados anômalos, além de identificar correlações entre variáveis e diferentes regimes operacionais da planta de produção de cloro e soda. Os modelos ajustados para os diferentes circuitos de células de eletrólise, bem como para a etapa de evaporação, apresentaram boa concordância com os dados operacionais. Isto possibilitou sua utilização para simular a operação das unidades de células eletrolíticas e evaporação no processo industrial de produção de cloro-soda, com células tipo diafragma. O modelo matemático baseado em redes neurais foi utilizado em estudos de otimização do processo, de modo a maximizar o ganho financeiro na unidade industrial, para uma dada condição de operação. / The present work consists on the development of a mathematical model on an industrial chlorine and sodium hydroxide production plant, aiming at the optimization of production efficiency and costs saving concerning electrical energy and vapor consumption. Two process steps were considered in the study: electrolysis and NaOH-liquor concentration by evaporation. Since there are no adequate models reported in the literature for simulating electrolysis-based processes like the one considered, empirical models for the different types of electrolysis cells were developed based on the fitting of neural networks to operational data from industrial operation. In this case, feedforward neural networks containing three neuron layers were fitted to the data. The raw data obtained from industrial operation at Carbocloro plant, in Cubatão ? SP, were first treated by means of multivariate statistical techniques, with the purpose of detecting and eliminating data containing gross errors and outliers, as well as to identify correlations among variables and different operational regimes of the industrial plant. Although material and energy balances for the evaporation step have been initially adopted, this approach could not be used in simulations due to the lack of valid models to predict liquid ? vapor equilibria for the specific system. Thus, a neural network model was also fitted to data from operation of the evaporation step. Fitting of the neural network models resulted in good agreement between model predictions and measured values of the model output variables, and this enabled their use in simulation studies for the electrolysis and evaporation process steps. The neural network-based mathematical model was utilized in process optimization studies aiming at the best financial gain under given operational conditions.

Os sistemas térmicos operam na maior parte do tempo fora de suas condições nominais de projeto. Nos sistemas de refrigeração industrial, a operação com carga térmica parcial ocorre em função de diversos fatores e o consumo de energia apresenta grande variação em função do ciclo de operação. Neste trabalho é proposta a otimização energética dos sistemas frigoríficos por compressão a vapor através da operação com regime variável para o ciclo frigorífico, especificamente através da operação com set-point de temperatura de evaporação variável. Para tanto é desenvolvido um modelo matemático para simulação dinâmica de um sistema de refrigeração industrial por compressão a vapor com refrigerante amônia (R-717) para o congelamento de alimentos composto basicamente de túnel de congelamento por circulação forçada de ar, evaporador com recirculação de líquido, reservatório de líquido a baixa pressão, compressores parafuso e condensador evaporativo atmosférico. São analisados através de simulação dois métodos para a variação do setpoint de temperatura de evaporação: a máxima temperatura de evaporação admissível e a minimização da potência no compressor. Os dois métodos são comparados ao sistema de controle de capacidade atualmente utilizado em instalações industriais. / Thermal systems operate most of the time at off-design conditions. In industrial refrigeration systems, the operation in partial loads occurs for many different reasons and the power consumption is a function of the refrigeration cycle pressures. This work proposes an energetic optimization of the compression refrigeration systems by the operation with a variable refrigeration cycle, specifically, by the operation with a variable suction temperature set-point. For this purpose it is developed a mathematical model for dynamic simulation of a industrial refrigeration compression system for food freezing with ammonia refrigerant (R717) formed by an air blast belt freezer, liquid overfeed evaporators, low pressure receiver, screw compressors and evaporative condenser. Two procedures for the suction temperature set-point variation are analyzed by simulation: the maximum suction temperature permitted and the compressor power consumption minimization. Both methods are compared with the capacity control system used in present industrial facilities.