The price and accessibility of fossil fuels, especially crude oil, are subject to considerable fluctuations due to growing demand on energy, limited resources, and energy security concerns. In addition, climate change caused by burning of fossil fuels is a challenge that energy sector is currently facing. These challenges incentivize development of alternative processes with no greenhouse gas emissions that can meet transportation fuels, chemical liquids, and electricity demands. Coal-based processes are of particular interest because coal price is both low and stable. However, these processes have a large environmental impact and are also less economically attractive than natural gas based plants due to the recent significant drop in natural gas price. However, even for natural gas plants, attempts to reduce CO2 emissions by using traditional CO2 capture and sequestration technologies not only decrease the thermal efficiency and profitability of the plant significantly but still release some CO2 to the atmosphere. The aim of this thesis is to develop, simulate and optimize an integrated polygeneration plant that uses multiple feedstocks and produces multiple products with low to zero CO2 emissions. Several process alternatives are investigated in this work to show the effect of each feedstock and product on the performance of the proposed plant. A comprehensive study is performed in each section, including process simulation in Aspen Plus software, development of custom models required for some units, as well as cost analysis by using Aspen Icarus software and empirical cost estimations from literature. Moreover, derivative free optimization techniques such as particle swarm optimization (PSO), genetic algorithm (GA) and simulated annealing (SA) are implemented to drive the design to economically optimum conditions as a function of the market price and carbon taxes. The final model will also introduce emerging technologies that can achieve higher efficiency and lower CO2 emissions compared to commercial systems, such as chemical looping gasification, chemical looping combustion, nuclear heat reforming, etc. By integrating multiple feedstocks and processes, the model can exploit certain synergies which are unavailable to traditional plants, resulting in significant efficiency improvements. In addition to power and liquid fuels, this polygeneration process offers benefits for petrochemical plants. Despite limited worldwide crude oil reserves, the demand for petrochemical products is still growing fast and it is highly important for petrochemical industry to find new resources as feedstock and diversify their supply chain network. By integration of the polygeneration plant in the same facility with novel processes that produce olefins (petrochemical feedstock) not from oil, but from syngas, it is possible to supply the required feed at lower cost than commercial steam cracking plants. / Thesis / Doctor of Philosophy (PhD)

This work focused on laser powder bed fusion (LPBF) of H13 tool steel to examine microstructure and melt pool morphology. Experiments were conducted with varying laser power (P) in the range of 90-180 W and scan speed (v) in the range of 500-1000 mm/s. layer thickness (l) and hatch spacing (h) were kept constant. Volumetric energy density (γ) was calculated using the above process parameters. In order to find a relation between the recorded density and top surface roughness with changing process parameters, set of equations were derived using the non-dimensional analysis. For any chosen values of laser power, scan speed, hatch spacing and layer thickness, these equations help to predict top surface roughness and density of LPBF processed H13 tool steel. To confirm the universal relation for these equations, data of In718 and SS316L processed in LPBF was input which gave a R-square of >94% for top surface roughness and >99% for density. A closed box approach, response surface model, was also used to predict the density and surface roughness which allows only in the parametric range. Material microstructures were examined to identify the melting modes such as keyhole, transition and conduction modes. X-ray diffraction data revealed that there was a presence of retained austinite in all the H13 printed samples. Elongated and equiaxed cellular structure were observed in higher magnifications due to solidification rate and thermal gradient.

Laser Powder Bed Fusion (L-PBF) is a metal additive manufacturing technique that uses a laser beam as a heat source to melt metal powder selectively. Because of the process small layer thicknesses, laser beam diameter, and powder particle size, L-PBF allows the fabrication of novel geometries and complex internal structures with enhanced properties. However, the main disadvantages of the L-PBF process are high costs and a lengthy production time. As a result, shortening the manufacturing process while maintaining comparable properties is exceptionally beneficial. Inconel 625 (IN625) is a nickel-based superalloy becoming increasingly popular in marine, petroleum, nuclear, and aerospace applications. However, the properties of IN625 parts produced by casting or forging are challenging to control due to their low thermal conductivity, high strength and work hardening rate, and high chemical complexity. Furthermore, IN625 alloy is regarded as a difficult-to-machine material. As a result, it is worthwhile to seek new technologies to manufacture complex-shaped IN625 parts with high dimensional accuracy. IN625 alloy is known for its excellent weldability and high resistance to hot cracking; thus, IN625 alloy appears to be a promising candidate for additive manufacturing. This thesis presents an experimentally focused study on optimizing L-PBF processing parameters in IN625 superalloy to increase process productivity while maintaining high material density and hardness. This study had four stages: preliminary, exploratory, modelling, and optimization. The first stage was devoted to conducting a literature review and determining the initial processing parameters. The second stage concentrated on determining the process window, for which single tracks were printed with two high levels of laser power (300, 400 W), five levels of scan speed (500, 700, 900, 1100, 1300 mm/s), and five levels of powder layer thickness (30, 60, 90, 120, 150 µm). Then, the process window was defined after investigating the top views and cross-sections of the tracks. Stage 3 involved printing 48 cubes (10 × 10 × 10 mm^3) with a laser power of 400 W, scan speeds of (700, 900, 1100, 1300 m/s), layer thicknesses of (60, 90, 120, 150 µm), and overlap percentages of (10, 30, 50%). As a result, the density of cubes was measured, and a statistical multiple regression analysis was used to predict it. Stage 4 involved estimating four sets of ideal processing parameters (based on statistical modelling of relative density) and printing 24 cubes (10 × 10 × 10 mm^3), six samples for each set. Finally, the relative density, hardness, and productivity of the samples were assessed, and a trade-off was determined. Even with the thickest powder layer of 150 µm (highest process productivity), samples with a mean relative density greater than 99% (i.e., 99.31% by Archimedes principle and 99.82% by image analysis) were printed. These findings are consistent with previously published results for L-PBF IN625 samples manufactured with smaller layer thicknesses ranging from 20 to 40 µm while maintaining comparable material hardness. The findings of this study are noteworthy because IN625 parts can be printed with higher powder layer thicknesses (less production time) while retaining similar material properties to those published with typical layer thicknesses ranging from 20 to 40 µm. Reduced production time due to optimized processing parameters can lead to significant energy and cost savings. / Thesis / Master of Applied Science (MASc)

No description available.

No description available.

No description available.

As the world becomes aware of its limited resources it is increasingly important to consider the development of buildings which could respond to the requirements of sustainability. During the last decades the development of the so-called green buildings has been gaining momentum through the implementation of appropriate reference standards, new technologies, innovative design strategies and processes. Such changes introduced new challenges for all subjects involved and, most of all, the need of working with new technologies and services through fully-integrated processes. Designers are also affected by such issue and, within this scope, project management plays a key role for the optimization of the design-project development. This research analyzes the design process of four case-study projects from the project management perspective taking into consideration all sustainability-related tasks and activities that negatively affected the project design development. A new methodology was created in order to analyze the design process and evaluate the effect of detected project-management issues under three main independent variables related to costs, time and sustainability. The research makes full use of the Lean approach to classify the issues, or wastes, experienced during the different design processes and to identify possible solutions for the process optimization. The four case studies are referred to four real projects developed in different European countries under the LEED and BREEAM reference standards. More specifically the four projects are: - One nursing-home located Northern Italy certified under the LEED reference standard. - One school-complex located in Northern Italy certified under the LEED reference standard. - One office building located in Barcelona (Spain) certified under the LEED reference standard. - One office building located in South-East of Spain certified under the BREEAM reference standard. The final scope of the research is to develop a methodology for the analysis of the green-building design processes from the project management perspective in order to identify the problems occurred, optimize the process and provide a tool to prevent unnecessary wastes of money, time and sustainability features. / Cada vez mas el mundo toma consciencia de que la disponibilidad de recursos naturales es limitada y el desarrollo de edificios sostenibles se está convirtiendo en una necesidad. Durante las últimas decadas el desarrollo de edificios sostenibles ha sido impulsada por el desarrollo de protocolos especificos, nuevas tecnologias, diseños y procesos inovadores. Dichos cambios han implicado nuevos retos para todos los sujetos involucrados y, sobretodo, la necesidad de operar con nuevas technologías y servicios a través de procesos integrados. Los proyectistas también quedan afectados por dichos cambios y el project management juega un papel imprescindible de cara a la optimización de procesos de diseño integrados. Esta investigación analiza el proceso de diseño de cuatro casos de studio desde el punto de vista del project management enfocando la atención en las actividades relacionadas con la sostenibilidad que afectaron negativamente el desarrollo de los procesos. Se desarrolla una nueva metodología para analizar el proceso de diseño y evaluar los efectos de eventuales fallos experimentados durante los procesos de project management desde la perspectiva de tres variables independientes relacionadas con: costes, tiempos y sostenibilidad. La investigación implementa los conceptos de la metodología Lean para la clasificación de los fallos, o desperdicios, occurridos durante el desarrollo de los varios procesos y para identificar posibles soluciones de cara a la optimización del proceso. Los cuatro casos de estudio están relacionados a cuatro proyectos reales desarrollados en diferentes estados Europeos a través de los protocolos LEED y BREEAM. Mas en detalle los proyectos son - Una residencia para mayores ubicada en Italia del Norte y certificada a través del protocolo LEED. - Un complejo escolar ubicado en Italia del Norte y certificado a través del protocolo LEED. - Un edificio para oficinas ubicado en Barcelona (España) y certificado a través del protocolo LEED. - Un edificio para oficinas ubicado en el Sureste de España y certificado a través del protocolo BREEAM. El objetivo final de la presente investigación es el desarrollo de una nueva metodología para el análisis de los procesos de diseño para edificios sostenibles desde el punto de vista del project management para identificar los problemas occurridos, optimizar el proceso y proporcionar una herramienta a los futuros técnicos para prevenir el desperdicio de dinero, tiempo y caracteristicas de sostenibilidad. / Cada vegada més el món té una major consciència que la disponibilitat de recursos naturals és limitada i el desenvolupament d'edificis sostenibles s'està convertint en una necessitat. Durant les últimes dècades el desenvolupament d'edificis sostenibles ha estat impulsat pel desenvolupament de protocols específics, noves tecnologies, dissenys i processos innovadors. Aquests canvis han implicat nous reptes per a tots els subjectes involucrats i, sobretot, la necessitat d'operar amb noves tecnologies i serveis a través de processos integrats. Els projectistes també queden afectats per aquests canvis i el project management juga un paper imprescindible de cara a l'optimització de processos de disseny integrats. Esta investigació analitza el procés de disseny de quatre casos d' estudi des del punt de vista del project management fixant l'atenció en les activitats relacionades amb la sostenibilitat que van afectar negativament el desenvolupament dels processos. Es va a desenvolupar una nova metodologia per analitzar el procés de disseny i avaluar els efectes d'eventuals errors experimentats durant els processos de project management des de la perspectiva de tres variables independents relacionades como son: costos, temps i sostenibilitat. La investigació implementa els conceptes de la metodologia Lean per a la classificació dels errors, o deixalles, aparegudes durant el desenvolupament dels diversos processos, per identificar possibles solucions de cara a l'optimització dels processos. Els quatre casos d'estudi estan relacionats a quatre projectes reals desenvolupats en diferents estats Europeus a través dels protocols LEED i BREEAM: - Una residència per a gent major situada a Itàlia del Nord i certificada mitjançant el protocol LEED. - Un complex escolar situat a Itàlia del Nord i certificat a través del protocol LEED. - Un edifici per a oficines situat a Barcelona (Espanya) i certificat a través del protocol LEED. - Un edifici per a oficines situat en el Sud Este d'Espanya i certificat a través del protocol BREEAM. L'objectiu final de la present investigació és el desenvolupament d'una nova metodologia per a l'anàlisi dels processos de disseny en edificis sostenibles des del punt de vista del project management, per identificar els problemes possibles, optimitzar els processos i proporcionar una eina als futurs tècnics per prevenir el malbaratament de diners, temps i característiques de sostenibilitat. / Orsi, A. (2017). THE DEVELOPMENT OF GREEN-BUILDING PROJECTS: OPTIMIZATION OF THE PROJECT-MANAGEMENT PROCESSES THROUGH THE LEAN APPROACH [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/89098

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This study developed and optimised zinc oxide (ZnO) nanowire-based nanogenerator. The nanogenerator works on the piezoelectric effect that is, a mechanical force is converted to an electrical voltage. The ZnO nanowires are piezoelectric and when any force is applied to the nanowires an output voltage is generated. This ZnO nanowire-based nanogenerator can be used to power small electronic devices, such as pacemakers. The nanogenerator can also be incorporated into clothes and shoes to generate electricity to charge a cell phone for example. The problem experienced currently is that the nanogenerator does not generate enough electricity to be of practical use and needs to be further optimised. Simulations and mathematical models were used to identify areas where the nanogenerator could be optimised in order to increase the output voltage. It is shown that the morphology of the nanowires can have a considerable effect on the output voltage. For this reason the growth of the nanowires was investigated first. Different methods were used to propagate the nanowires in order to select the method that, on average, has the highest output voltage. Accordingly, one parameter at a time and design of experiments were used to optimise the nanowire growth. Consequently, these two methods were used to optimise the growth parameters with the respect to the output voltage. The aqueous solution method was found to yield nanowires that give the highest generated output voltage. After growing over 600 nanowire samples, optimal growth parameters for this method were found. These optimal growth parameters were subsequently used to grow nanowires that were used to manufacture the nanogenerator. The nanowires were grown on a solid substrate and hence the nanogenerator was also manufactured on the solid substrate. Through various optimisations of the manufacturing process the maximum output voltage achieved was about 500 mV. However, this output voltage is too low to be of practical use, even though the output has been raised considerably. The main problem was found to be the fact that the contact between the nanowires and the electrode was weak due to contamination. A new method was therefore required where the electrode and the nanowires would be in proper contact to ensure that higher output voltages were achieved. Subsequently, a flexible nanogenerator was manufactured in order to solve this problem. Accordingly, the nanowires were grown on the flexible polyimide film and a buffer layer was then spun onto the flexible substrate, leaving only the nanowire tips exposed. The electrode was then sputtered on top of this buffer layer, covering the nanowire tips. This ensured proper contact between the nanowires and the electrode. The nanogenerator, which was manufactured with non-optimal growth parameters, gives a maximum voltage output of 1 V, double the maximum achieved with the solid nanogenerator. When the optimal growth parameters were used the output voltage was raised to 2 V. Various optimisation techniques were performed on the nanogenerator, including plasma treatment and annealing and the use of various materials in the buffer layer. Combining these optimisation methods subsequently led to an optimised nanogenerator that can generate an output voltage of over 5 V. This was achieved after over 1200 nanogenerators had been manufactured. However, the output voltage was not in a usable form. Circuitry was therefore developed to transform the voltage generated by the nanogenerator to a useable form. The best circuit, the LTC3588, was used to power an LED for 10 seconds. The completed device was found to achieve a power output of 0.3 mW, enough for small electronic devices. / AFRIKAANSE OPSOMMING: ‘n Sink-oksied (ZnO) nanodraad gebaseerde nanogenerator is ontwikkeld en geöptimeer. Die nanogenerator werk met behulp van die piezoelektriese effek - meganiese krag work omgesit in ‘n elektriese spanning. Die ZnO nanodrade is piezoelektries en wanneer ‘n krag op die drade aangewend word, word ‘n uittree spanning gegenereer. Die nanogenerator kan gebruik word om klein elektroniese toestelle, soos ‘n pasaangeër, van krag te voorsien. Die nanogenerator kan in klere en skoene geïnkorporeer word om elektrisiteit op te wek vir die laai van ‘n selfoon. Die probleem is egter dat die nanogenerator tans nie genoeg krag opwek om prakties van nut te wees nie en verdere optimasie word benodig. Simulasies en wikundige modelle work gebruik om areas te identifiseer waar die nanogenerator geöptimeer kan word, met die doel om die uittreespanning te verhoog. Dit word bewys dat die morfologie van die nanodrade ‘n groot effek het op die uittreespanning. Dus word die groei van die nanodrade eerste ondersoek. Verskillende metodes word gebruik om die nanodrade te groei en die beste metode, wat die hoogste uittreespanning op gemiddeld verskaf, word gekies. Een parameter op ‘n slag en ontwerp van eksperimente word gebruik om die nanodraad groei te optimeer. Die groei parameters word geöptimeer deur van die twee metodes gebruik te maak, en die optimeering word gedoen in terme van die uittreespanning. Die oplossing groei metode lei tot nanodrade wat die hoogste uittreespanning verskaf. Na oor die 600 nanodraad monsters gegroei is, is die optimale parameters gevind. Hierdie optimale parameters word uitsluitlik gebruik om die nanogenerator te vervaardig. Die nanodrade word op ‘n soliede substraat gegroei en dus word die nanogenerator op dieselfde soliede substraat vervaardig. Verskeie metodes is gebruik om die vervaardiging te optimeer en die hoogste uittreespanning wat bereik is, is 500 mV. Die uittreespanning is te laag om van praktiese nut te wees alhoewel dit heelwat verhoog is. Die grootste probleem is die swak kontak tussen die nanodrade en die elektrode, wat veroorsaak word deur kontaminasie. ‘n Nuwe metode word verlang wat beter kontak tussen die nanodrade en elektrode sal verseker. ‘n Buigbare nanogenerator is vervaardig om die probleem op te los. Die nanodrade word nou op ‘n buigbare film gegroei. ‘n Bufferlaag word tussen die nanodrade in gedraai, tot net die punte van die nanodrade nog sigbaar is. Die elektrode word bo-op die bufferlaag gedeponeer, wat behoorlike kontak tussen die nanodrade en elektrode verseker. Die nanogenerator wat met nie-optimale groei parameters vervaardig is, bereik ‘n uittreespanning van 1 V, dubbel die soliede nanogenerator. Met optimale groei parameters word die uittreespanning tot 2 V verhoog. Verskeie optimasie tegnieke word op die nanogenerator toegepas. Die metodes sluit in suurstof plasma behandeling, verhitting en die inkorporasie van verskillende materiale in die bufferlaag. ‘n Kombinasie van die metodes geïnkorporeer in een nanogenerator lei tot ‘n uittreespanning van 5 V. Die uittreespanning is bereik na oor die 1200 nanogenerators vervaardig is. The uittreespanning is nog nie in ‘n bruikbare vorm nie. Spesiale stroombane is ontwikkel wat die nanogenerator spanning omskakel na ‘n bruikbare vorm. Die beste stroombaan, die LTC3588, kan ‘n LED aanskakel vir 10 sekondes. The toestel kan ook 0.3mWuittreekrag voorsien, genoeg vir klein elektroniese toestelle om te werk.

Business process reengineering (BPR) was analyzed as one of the approaches to considerably improve the performance of the enterprise. The actuality of BPR in times of economic downturn was evaluated. The historic evolution of the concept was examined and findings about the economic nature of BPR emergence were made. The dependence of BPR actuality and simplicity of BPR usage on the level of enterprise business process maturity was shown. A conclusion about optimal point was made via depicting the interrelations graphically. Advantages of BPR usage for enterprises of different sizes were proved and specified. Benefits of BPR were compared with benefits of other related methods like ERP, JIT, TQM and Continuous Improvement. The future possible development of the BPR was analyzed. There offered possible further directions of research in the area of BPR based on current limitations of the concept. Results of the research may be used in companies of maturity level one to three, taking into account size of the company and current state of business process maturity.

O ácido lático produzido por bactérias láticas constitui um sério problema nas fermentações industriais. Por este motivo, os efeitos deste ácido adicionado sobre a produção de etanol por levedura em meio sintético foi estudado no presente trabalho. Assim, foi possível evitar a interferências de um processo contendo uma cultura mista de bactérias láticas e levedura. Além disto, o meio sintético foi utilizado a fim de evitar as variações na composição da matéria-prima, no caso o melaço de cana-de-açúcar, durante a estocagem por um longo período de tempo. Inicialmente, dois planejamentos fatoriais foram realizados em batelada simples. Após a validação deste sistema, uma produção máxima de etanol (72,1 g.L-1) e uma boa retenção de viabilidade celular (86,4%) foram conseguidas utilizando-se inóculo bastante alto (40 g.L-1, massa seca) numa fermentação contendo 200 g.L-1 de sacarose inicial. Nestas condições, experimentos em batelada simples em mini-reatores foram realizados operando a 34 °C e em presença de 0 a 1,0 g.L-1 de ácido lático. Neste experimento, o pH do meio tornou-se bastante baixo (2,3 a 2,7). Por este motivo, outra fermentação em batelada simples foi realizada com o reajuste do pH inicial para 4,5 logo após adição de todos os componentes ao reator. O reajuste do pH inicial causou um aumento significativo tanto na produtividade e na velocidade específica máxima de etanol quanto na viabilidade final na batelada simples. Depois disto, comparações da batelada simples com a batelada alimentada continuamente e por pulsos também foram realizadas em presença de ácido lático. Observou-se que o processo de batelada com alimentação contínua consumiu açúcar mais lentamente, apresentou maior perda em viabilidade e maior produção de biomassa que a batelada simples enquanto que o processo de batelada alimentada por pulsos foi bem semelhante. A elevação da concentração do ácido lático (2,0 g.L-1 a 4,0 g.L-1) nos reatores permitiu a tamponagem do meio sintético logo após o reajuste inicial de pH para 4,5. Nestas condições, também houve semelhança entre os processos de batelada simples e batelada alimentada por pulsos. Em batelada alimentada por pulsos, verificou-se que a diminuição da quantidade de inóculo levou a perdas de viabilidade celular por causa do aumento do ácido externo em relação à quantidade de células no reator. De uma maneira geral, a presença de ácido lático causou aumentos no consumo de açúcar em todos os processos. Fermentações sucessivas foram realizadas, adicionado 3 pulsos de sacarose e 2,0 g.L-1 de ácido lático (em relação ao volume final do meio), a levedura 63M passou por um processo de adaptação até o terceiro ciclo. Além disto, houve uma redução na proteína intracelular final e um aumento na acidez total em presença ácido lático. No entanto, a produção de glicerol e a produção de trealose aumentaram e foram semelhantes tanto em presença quanto em ausência de pulsos de ácido lático. / Lactic acid produced by lactic bacteria is a problem serious in fermentation alcohol plants. For this reason, the effects of this added acid on ethanol by yeast in synthetic medium were studied in the present work. Thus, it was possible to avoiding interferences of a process containing a miscellaneous culture of lactic bacteria and yeast. Besides, synthetic medium was used to avoiding variations in raw material, sugar-cane molasses in this case, during the storage by a large period of time. Initially, two factorial planning were used in simple batch under agitation. After validation of these plannings, maximal ethanol production (72.1 g.L-1) with well retention of viability (86,4%) were obtained using high inoculum size (40 g.L-1, dry weight) in fermentation containing 200 g.L-1 initial sucrose. In these conditions, fermentations in simples batch in mini-reactors were carried out at 34 °C and in presence of 0 to 1,0 g.L-1 added lactic acid. In this experiment, the medium pH became very small (2.3 to 2.7). For this reason, another fermentation in simple batch was realized with initial pH readjusted for 4,5 after addition of all of medium compounds in the reactor. The readjusted of initial pH caused a significative increase as in productivity and maximal-specific rate of ethanol as in final viability in simple batch process. After this, comparisons among simple batch and continuous-fed batch and pulses-fed batch were made in the presence of lactic acid. In these experiments, continuous-fed batch process showed sugar uptake more slowly, showed more drops in viability and more biomass production than simple batch process, while the pulses-fed batch was similar than simple batch process. In addition, the elevation of lactic acid concentration for 2,0 g.L-1 to 4,0 g.L-1 in the reactors permitted the pH maintenance of synthetic medium after initial pH readjusted for 4,5. In these conditions, the simple batch and pulses-fed batch processes also were similar. In pulses-fed batch culture, the decrease of inoculum size caused drops in viability because of the increase of endogenous acid in relation to cell quantity in the reactor. Generally, the presence of lactic acid causes increases in sugar uptake in all of process. Fermentations with cell reuse were carried out in fed batch process with pulses of sucrose and 2,0 g.L-1 lactic acid (in relation to final medium volume), yeast 63M undertook to adaptation process until the third fermentation cycle. In adittion, a decrease of final intracellular protein and an increase of total acidity in presence of lactic acid. However, glycerol and trehalose productions increased with the fermentative cycles and were similar as in presence as in absence of added lactic acid.