Estágio realizado na Bosch Termotecnologia, S. A. e orientado pelo Eng.º / Tese de mestrado integrado. Engenharia Industrial e Gestão. Faculdade de Engenharia. Universidade do Porto. 2009

<p> </p><p>Konkurrens med lågprisländer, ökade krav på kvalitet och behov av att snabbt nå ut på marknaden med nya produkter är anledningar till att företag måste se över och effektivisera sina testmetoder. För att säkerställa nöjda kunder över tid krävs tillförlitliga produkter som uppfyller sin tänkta funktion så länge företaget önskar det. Kostnader för bristande kvalitet i form av reparationer, återkallning eller försenad produktrelease är ofta stora och ett sätt att minska de är genom att effektivisera sin testning.</p><p>Syftet med detta examensarbete är att ta fram samt utvärdera en effektiv testmetod vilken möjliggör identifiering av svaga länkar i en konstruktion med så få testobjekt och så snabbt som möjligt. Arbetet är utfört på företaget Whirlpool Corporation i Norrköping, på produkten mikrovågsugnar.</p><p>I detta examensarbete redogörs för en testmetod, som är framtagen huvudsakligen baserad på teorin bakom Highly Accelerated Life Test <em>(HALT)</em>. HALT innebär testning under höga stressnivåer med intentionen att produkten ska gå sönder för att således exponera svaga länkar. Testmetoden resulterar i en modell framtagen med avsikt att möjliggöra konstruktionsändringar som leder till en ökad tillförlitlighet hos produkten. Modellen startar med en kartläggning av de fel som uppkommer på marknaden, därefter listas de stressfaktorer som kan orsaka fel. Sedan väljs testobjekt samt stressfaktor och baserat på detta designas och byggs testutrustning. Produkten placeras i testutrustningen så att den kan övervakas och manövreras. Sedan påförs den valda stressen, stegvis, det vill säga gradvis ökande, fram tills att något går sönder. Analys sker av felet och det åtgärdas om det är möjligt med avseende på teknologiska och ekonomiska begränsningar. Detta förfarande gör produkten mer tillförlitlig, eftersom svaga länkar identifieras och elimineras.</p><p>Testerna har utförts med hjälp av utrustning vilken redan fanns på Whirlpool, teorin kring HALT kräver vanligen speciell testutrustning, så kallade kaosmaskiner. Detta examensarbete har dock visat ett exempel på att även enklare utrustning kan användas i syfte att ta fram relevanta fel, och således möjligheter till förbättringar.</p><p>Utvärderingen av testmetoden har i examensarbetet genomförts som ett proof of concept, det vill säga en evaluering med syfte att finna bevis för att testmetoden fungerar. Test har således genomförts på en mogen produkt, där statistik finns från marknaden kring vilka fel som uppkommit hos kund. Genom att testa två enheter enligt metoden med stressfaktorn vibration och jämföra felen som uppkom med de som uppkommit på marknaden kan bevis för metoden erhållas. Överensstämmande fanns mellan marknadsfelen och testfelen. Således tycks modellen fungera att applicera på Whirlpools produkter.</p><p>Ett sätt att implementera resultatet från dessa tester i framtida konstruktioner är att lägga större fokus på resonanspunkterna för olika komponenter. Examensarbetet har visat att skador ofta uppkommer för olika komponenter vid just resonanspunkterna, att konstruera för att undvika att dessa uppkommer under produktens livscykel är således ett sätt att erhålla tillförlitligare produkter.</p><p>Sammantaget visar denna rapport hur och att den föreslagna modellen kan nyttjas i syfte att finna svaga länkar snabbt med endast ett fåtal testobjekt, genom att testa vid höga stressnivåer under kort tid. Efter åtgärdande av de svaga länkarna erhålls tillförlitligare produkter och i slutändan nöjdare kunder.</p> / <p> </p><p> </p><p>Competition against low price countries, increased demands on high quality products and the need to quickly launch new products on the market are reasons why companies need to look over and increase the efficiency of their test methods. To guarantee customer satisfaction over time, companies need reliable products that fulfill their intended function for as long as the company wishes them to. Costs arising from poor quality such as repairs, warranty costs, recalls and delayed product releases are often large and one way to decrease them is to perform more efficient tests.</p><p>The purpose of this master thesis is to develop and evaluate an efficient test method which renders possible an identification of the weak links within a construction with as few test objects and as quickly as possible. The master thesis was carried out at the company Whirlpool Corporation in Norrköping, regarding the product microwave oven.</p><p>In this master thesis a test method is described, which is based on the theory behind Highly Accelerated Life Test (HALT). HALT represents testing with high levels of stress aiming at product failure, thus exposing weak links. The model is constructed with the aim of creating opportunities for design changes, therefore increasing the reliability of the product. The test method results in a model which starts with a mapping of the failures that occur in the field. After that the stresses that can cause failures are listed. Afterwards, a test object and a stress is chosen. Based on this, a test appliance is designed and built. The product is placed in the test equipment so that it can be monitored and maneuvered. The stress is then applied step by step, i.e. gradually increased, until something fails. An analysis is carried out regarding the failure, which is corrected if possible depending on technological and financial limitations. This procedure increases the reliability of the product because weak links are identified and eliminated.</p><p>The tests have been performed with already existing equipment at Whirlpool. The theory regarding HALT usually demand special test equipment, so called chaos machines. This master thesis shows an example that less advanced equipment can be used in finding relevant failures, and therefore opportunities for improvement.</p><p>The evaluation of the method in this master thesis has been carried out as a proof of concept, meaning an evaluation with the purpose of finding proof that the test method is valid. Tests have therefore been performed on a mature product, where statistics collected from the field regarding field failures existed. By testing two units according to the defined method with the stress vibration and a comparison between the failures that occurred with the ones that have occurred on the field can be performed, proof can be provided that the method works. Accordance was found between the field failures and the test failures. The model therefore seems to be work when it is applied on Whirlpool’s products.</p><p>One way to implement the results from these tests in future constructions is to emphasis the importance of resonance points for different components, since the master thesis has shown that failures often occur for different components at their resonance points. Designing with the goal to avoid that the product is exposed to their resonance points will make the products more reliable.</p><p>To summarize, this report shows how it is possible, by using the suggested model, to find weak links quickly with only a few test objects and by testing with high levels of stress during a short period of time. After attending to the weak links more reliable products can be designed and constructed, resulting in higher customer satisfaction.</p>

Konkurrens med lågprisländer, ökade krav på kvalitet och behov av att snabbt nå ut på marknaden med nya produkter är anledningar till att företag måste se över och effektivisera sina testmetoder. För att säkerställa nöjda kunder över tid krävs tillförlitliga produkter som uppfyller sin tänkta funktion så länge företaget önskar det. Kostnader för bristande kvalitet i form av reparationer, återkallning eller försenad produktrelease är ofta stora och ett sätt att minska de är genom att effektivisera sin testning. Syftet med detta examensarbete är att ta fram samt utvärdera en effektiv testmetod vilken möjliggör identifiering av svaga länkar i en konstruktion med så få testobjekt och så snabbt som möjligt. Arbetet är utfört på företaget Whirlpool Corporation i Norrköping, på produkten mikrovågsugnar. I detta examensarbete redogörs för en testmetod, som är framtagen huvudsakligen baserad på teorin bakom Highly Accelerated Life Test (HALT). HALT innebär testning under höga stressnivåer med intentionen att produkten ska gå sönder för att således exponera svaga länkar. Testmetoden resulterar i en modell framtagen med avsikt att möjliggöra konstruktionsändringar som leder till en ökad tillförlitlighet hos produkten. Modellen startar med en kartläggning av de fel som uppkommer på marknaden, därefter listas de stressfaktorer som kan orsaka fel. Sedan väljs testobjekt samt stressfaktor och baserat på detta designas och byggs testutrustning. Produkten placeras i testutrustningen så att den kan övervakas och manövreras. Sedan påförs den valda stressen, stegvis, det vill säga gradvis ökande, fram tills att något går sönder. Analys sker av felet och det åtgärdas om det är möjligt med avseende på teknologiska och ekonomiska begränsningar. Detta förfarande gör produkten mer tillförlitlig, eftersom svaga länkar identifieras och elimineras. Testerna har utförts med hjälp av utrustning vilken redan fanns på Whirlpool, teorin kring HALT kräver vanligen speciell testutrustning, så kallade kaosmaskiner. Detta examensarbete har dock visat ett exempel på att även enklare utrustning kan användas i syfte att ta fram relevanta fel, och således möjligheter till förbättringar. Utvärderingen av testmetoden har i examensarbetet genomförts som ett proof of concept, det vill säga en evaluering med syfte att finna bevis för att testmetoden fungerar. Test har således genomförts på en mogen produkt, där statistik finns från marknaden kring vilka fel som uppkommit hos kund. Genom att testa två enheter enligt metoden med stressfaktorn vibration och jämföra felen som uppkom med de som uppkommit på marknaden kan bevis för metoden erhållas. Överensstämmande fanns mellan marknadsfelen och testfelen. Således tycks modellen fungera att applicera på Whirlpools produkter. Ett sätt att implementera resultatet från dessa tester i framtida konstruktioner är att lägga större fokus på resonanspunkterna för olika komponenter. Examensarbetet har visat att skador ofta uppkommer för olika komponenter vid just resonanspunkterna, att konstruera för att undvika att dessa uppkommer under produktens livscykel är således ett sätt att erhålla tillförlitligare produkter. Sammantaget visar denna rapport hur och att den föreslagna modellen kan nyttjas i syfte att finna svaga länkar snabbt med endast ett fåtal testobjekt, genom att testa vid höga stressnivåer under kort tid. Efter åtgärdande av de svaga länkarna erhålls tillförlitligare produkter och i slutändan nöjdare kunder. / Competition against low price countries, increased demands on high quality products and the need to quickly launch new products on the market are reasons why companies need to look over and increase the efficiency of their test methods. To guarantee customer satisfaction over time, companies need reliable products that fulfill their intended function for as long as the company wishes them to. Costs arising from poor quality such as repairs, warranty costs, recalls and delayed product releases are often large and one way to decrease them is to perform more efficient tests. The purpose of this master thesis is to develop and evaluate an efficient test method which renders possible an identification of the weak links within a construction with as few test objects and as quickly as possible. The master thesis was carried out at the company Whirlpool Corporation in Norrköping, regarding the product microwave oven. In this master thesis a test method is described, which is based on the theory behind Highly Accelerated Life Test (HALT). HALT represents testing with high levels of stress aiming at product failure, thus exposing weak links. The model is constructed with the aim of creating opportunities for design changes, therefore increasing the reliability of the product. The test method results in a model which starts with a mapping of the failures that occur in the field. After that the stresses that can cause failures are listed. Afterwards, a test object and a stress is chosen. Based on this, a test appliance is designed and built. The product is placed in the test equipment so that it can be monitored and maneuvered. The stress is then applied step by step, i.e. gradually increased, until something fails. An analysis is carried out regarding the failure, which is corrected if possible depending on technological and financial limitations. This procedure increases the reliability of the product because weak links are identified and eliminated. The tests have been performed with already existing equipment at Whirlpool. The theory regarding HALT usually demand special test equipment, so called chaos machines. This master thesis shows an example that less advanced equipment can be used in finding relevant failures, and therefore opportunities for improvement. The evaluation of the method in this master thesis has been carried out as a proof of concept, meaning an evaluation with the purpose of finding proof that the test method is valid. Tests have therefore been performed on a mature product, where statistics collected from the field regarding field failures existed. By testing two units according to the defined method with the stress vibration and a comparison between the failures that occurred with the ones that have occurred on the field can be performed, proof can be provided that the method works. Accordance was found between the field failures and the test failures. The model therefore seems to be work when it is applied on Whirlpool’s products. One way to implement the results from these tests in future constructions is to emphasis the importance of resonance points for different components, since the master thesis has shown that failures often occur for different components at their resonance points. Designing with the goal to avoid that the product is exposed to their resonance points will make the products more reliable. To summarize, this report shows how it is possible, by using the suggested model, to find weak links quickly with only a few test objects and by testing with high levels of stress during a short period of time. After attending to the weak links more reliable products can be designed and constructed, resulting in higher customer satisfaction.

Due to the rapid revolution in trading strategies, market environment is very different from the past, and the market intervention in national stock exchanges has been taken seriously again . However, very few studies discussed the rule-based trading suspension for individual stocks in the past, and most of them only focused on the impact of trading halt on market performance. For this reason, this study in addition to measures impact of market performance, another major analysis focuses on the differences between individual and institutional investors order behavior under different halt conditions. We try to understand whether the current halt mechanism achieves the purposes of reducing the information asymmetry and the abnormal volatility. The market performence empirical results show that transitory trading halt can reduce the overreaction of re-opening, but the halt of follow-up 5 minutes of the liquidity decreased, and volatility increased. Next, we find the individual investors order aggressive tend to be conservative in the period of suspension. In contrast, Institutional investor behavior will tend to be more positive with higher information asymmetry and will not be affected by the trading halt. Moreover, from follow-up 20 minutes individual-institutional transaction VWAP ratio, we find that the trading halt will improve the performance of individual investors transactions.

Acid sulphate soils is a wide spread problem along the northern coast of Sweden. This is causing great damage through low pH and leaching of metals out into the streams. These soils are estimated to be found in several places in Sweden but also in many other areas in the world. One of these areas in Sweden that are believed to contain these sediments is Mälardalen. The purpose of this study is to evaluate the extension of the acid sulphate soils in this area. This has been accomplished through measurements of pH in the field as well as laboratorial work such as measuring the organic substance in the soil. The soils sulphur content was also analysed in a number of the samples. A total of 29 places has been visited in the area. The examination has been done as a pilot survey for the SGU. The study wanted to confirm if the acid sulphate soils are a problem in Mälardalen and if there is a connection between the soils that has a high organic matter and by what time they were deposited, and that those attributes would be a link to a low pH. The results is indicating that there is some correlation, mainly when it comes to soils with high organic content that has been deposited around 1000 years ago. With these quality’s the probability is going to be higher to find a soil that has a low pH. When examining diagrams showing these relations, we get an R-square value for the trend lines from both cases showing a correlation of 30%. This give us the indication that there are also other factors which will affect the pH. In this study the pH has been used as an indicator to where acid sulphate soils could be located. One cannot say that a high pH will exclude the possibility for a soil to become an acid sulphate soil, in the cases where the oxidized zone is small or absent. To ensure this fact, the soil will need to be oxidized as well as analysed to establish the sulphur content in the sample. This thesis has not shown any difference when it comes to the potential of acidification caused by these soils and the event of different kinds of sulphur compounds in Norrland and Mälardalen. According to our fulfilled literature studies the main difference are supposed to lay in the variation of the grain size in the different kinds of sediments. Air diffuse slower into a soil with a high content of clay compared to a soil with more silt. Clay may also have a bigger buffer system though high CaCo3 content or a high cation exchange capacity. The samples from the sites of Brantshammar, Kungsängen and Hova got time to oxidize as well as going through a sulphur analysis. Though these examinations as well as evaluations in the field, these sites could be confirmed to be acid sulphate soils. The number of parameters that was analysed for the other sites in this study are said to be too few, and gave inadequate results, and not the amount of information needed to be able to confirm the soils as acid sulphate soils. However, the correlation and the probability did increase with the number of consistent variables. The area would need another survey when there have been findings of acid sulphate soils as well as potential acid sulphate soils in this area. Further investigations can supplement the results from this current study and give a more apparent picture of the area, due to the fact that only a smaller amount of places could be reached within the time range of this survey. / Sura sulfatjordar är ett utbrett problem längs Sveriges nordligaste kust och orsakar skada genom låga pH och urlakning av metaller ut i vattendrag. Ett av dessa områden i Sverige tros vara Mälardalen och syftet med det här arbetet var att undersöka utbredningen utav sura sulfatjordar där. Genom att mäta pH på olika djup ute i fält, analysera organisk halt i labb samt svavelhalt i ett antal prover, så har 29 olika platser i området undersökts. Arbetet utfördes som en pilotstudie åt SGU. Målet var att se om sura sulfatjordar utgör ett problem i Mälardalen, och huruvida det finns ett samband mellan jordar med högt organiskt innehåll, vid vilken tidpunkt då avsättningen bildats och om dessa egenskaper sammanfaller med låga pH. Resultaten tyder på att ett visst samband finns, främst när det gäller högre organisk halt i jorden och områden som torrlagts genom landhöjning under de senaste 1000 åren. Sammanfaller dessa parametrar ökar sannolikheteten för att jorden kommer ha låga pH. I diagram över dessa samband visar R-kvadratvärdet för trendlinjen i båda fallen en korrelation på ca 30 % vilket antyder att det även finns andra faktorer som pH är beroende av. Det ska dock tilläggas att pH i den här undersökningen har använts som en indikator på om en jord kan klassificeras som en sur sulfatjord. På en del platser där pH i nuläget är högt skulle sura sulfatjordar kunna bildas om grundvattenytan sänktes. För att säkerställa detta skulle jorden behöva oxideras och pH mätas igen för att sedan analyseras för att ta reda på svavelhalten. Studien har inte visat någon skillnad gällande försurningspotential till följd av olika sulfidföreningar i Norrland gentemot Mälardalen. Enligt utförda litteraturstudier skall skillnaden i stället främst ligga i kornstorleken hos de olika jordarterna. Luft har svårare att tränga ned i en jord med hög lerhalt än i en siltigare jord. Lera kan också ofta ha en större buffrande effekt genom hög katjonutbyteskapacitet. Tidigare undersökningar visar även att Mälardalens gyttjeleror kan ha ett högre CaCO3- innehåll än normalt, vilket även verkar buffrande. Från platserna Brantshammar, Kungsängen och Hova togs prover som fick oxidera och genomgå svavelanalys. Genom dessa undersökningar, samt bedömning i fält, kunde jordarna med säkerhet fastställas som sura sulfatjordar. Antalet parametrar som analyserats på de övriga platserna i undersökning gav inte tillräckligt underlag för att kunna klassificera jordarna som sur sulfatjord, däremot ökade sannolikheten med antal överensstämmande parametrar. Området skulle behöva undersökas grundligare då det har hittats sura sulfatjordar med låga pH, samt områden som potentiellt skulle kunna bli det i framtiden. Vidare undersökningar kan komplettera resultaten från denna undersökning och ge en tydligare bild över området då endast en mindre mängd platser hann undersökas i denna studie.

Por décadas, a qualidade de produtos é determinada por testes em ambientes de laboratório, como testes de acelerados de vibração, ciclagem térmica, choque mecânicos ou térmicos, entre outros. Porém, mais recentemente um novo tipo de técnica tem adquirido a confiança de pesquisadores e projetistas. As técnicas conhecidas como HALT (Highly Accelerated Life Testing) e HASS (Highly Accelerated Stress Screening), ou seja, testes acelerados e amplificados que submetem produtos a condições severas, têm mostrado sua importância e eficiência no âmbito da detecção de falha em produtos ainda na fase de produção. Este trabalho tem por objetivo desenvolver e implementar um algoritmo de controle baseado em métodos heurísticos para ser usado em ensaios acelerados usando um Shaker eletrodinâmico. Este controlador deve ser robusto o suficiente para se adequar a possíveis efeitos de ressonância do shaker que podem vir a alterar a dinâmica do sistema, inviabilizando controles tradicionais com parâmetros fixos. Os resultados obtidos através de vários ensaios mostraram que ambos os sistemas de controle são eficientes, pois o erro entre o sinal desejado (tensão mecânica ou aceleração) e os medidos experimentalmente, tendem rapidamente a zero não apresentando sobressinais consideráveis ou erro em regime permanente, tanto para frequência fixa quanto para varredura de frequência. A comparação entre o controlador tradicional PID e o controle heurístico baseado em Lógica Fuzzy, que foram aplicados no shaker eletrodinâmico, comprova que, para mudanças na amplitude do sistema, o controle Fuzzy apresentou menor sobressinal, o que é mais favorável do ponto de vista mecânico. Logo, a metodologia proposta pode ser aplicada para ensaios HALT/HASS com o intuito de obter grandes vibrações e, por conseguinte tensões, para identificar possíveis falhas de projeto e então, poder corrigi-las. / For decades, product quality is determined by environmental tests, such as accelerated vibration tests, thermal cycling, mechanical or thermal shock, and others. However, more recently a new type of test has gained the trust of researchers and designers. Known techniques such as HALT (Highly Accelerated Life Testing) and HASS (Highly Accelerated Stress Screening), or accelerated and amplified testing that submit products to severe conditions have shown their importance in the efficiency and fault detection in products still in production phase. This study aims to develop and implement a control algorithm based on heuristic methods in order to be used in a system of accelerated tests in an electrodynamic shaker. This controller must be robust enough to fit the resonance effects of the shaker that it can change the system dynamic, invalidating traditional controls with fixed parameters. The results obtained through tests showed both control systems are efficient, because the error between desired signal (mechanical stress and acceleration) and the experimentally measured tend rapidly to zero, there aren’t overshoots or steady state errors, both for constant frequency and for sweep frequency. Comparing the PID traditional control and the Logic Fuzzy control, applied in electrodynamic shaker, we proved that to change system amplitude, the fuzzy control presented lower overshoot, that is favorable from the standpoint of mechanical. Therefore, the methodology proposed can be applied to HALT/HASS tests in order to obtain large vibrations and, consequently stress, to identify possible flaws in the design and correct them.

Por décadas, a qualidade de produtos é determinada por testes em ambientes de laboratório, como testes de acelerados de vibração, ciclagem térmica, choque mecânicos ou térmicos, entre outros. Porém, mais recentemente um novo tipo de técnica tem adquirido a confiança de pesquisadores e projetistas. As técnicas conhecidas como HALT (Highly Accelerated Life Testing) e HASS (Highly Accelerated Stress Screening), ou seja, testes acelerados e amplificados que submetem produtos a condições severas, têm mostrado sua importância e eficiência no âmbito da detecção de falha em produtos ainda na fase de produção. Este trabalho tem por objetivo desenvolver e implementar um algoritmo de controle baseado em métodos heurísticos para ser usado em ensaios acelerados usando um Shaker eletrodinâmico. Este controlador deve ser robusto o suficiente para se adequar a possíveis efeitos de ressonância do shaker que podem vir a alterar a dinâmica do sistema, inviabilizando controles tradicionais com parâmetros fixos. Os resultados obtidos através de vários ensaios mostraram que ambos os sistemas de controle são eficientes, pois o erro entre o sinal desejado (tensão mecânica ou aceleração) e os medidos experimentalmente, tendem rapidamente a zero não apresentando sobressinais consideráveis ou erro em regime permanente, tanto para frequência fixa quanto para varredura de frequência. A comparação entre o controlador tradicional PID e o controle heurístico baseado em Lógica Fuzzy, que foram aplicados no shaker eletrodinâmico, comprova que, para mudanças na amplitude do sistema, o controle Fuzzy apresentou menor sobressinal, o que é mais favorável do ponto de vista mecânico. Logo, a metodologia proposta pode ser aplicada para ensaios HALT/HASS com o intuito de obter grandes vibrações e, por conseguinte tensões, para identificar possíveis falhas de projeto e então, poder corrigi-las. / For decades, product quality is determined by environmental tests, such as accelerated vibration tests, thermal cycling, mechanical or thermal shock, and others. However, more recently a new type of test has gained the trust of researchers and designers. Known techniques such as HALT (Highly Accelerated Life Testing) and HASS (Highly Accelerated Stress Screening), or accelerated and amplified testing that submit products to severe conditions have shown their importance in the efficiency and fault detection in products still in production phase. This study aims to develop and implement a control algorithm based on heuristic methods in order to be used in a system of accelerated tests in an electrodynamic shaker. This controller must be robust enough to fit the resonance effects of the shaker that it can change the system dynamic, invalidating traditional controls with fixed parameters. The results obtained through tests showed both control systems are efficient, because the error between desired signal (mechanical stress and acceleration) and the experimentally measured tend rapidly to zero, there aren’t overshoots or steady state errors, both for constant frequency and for sweep frequency. Comparing the PID traditional control and the Logic Fuzzy control, applied in electrodynamic shaker, we proved that to change system amplitude, the fuzzy control presented lower overshoot, that is favorable from the standpoint of mechanical. Therefore, the methodology proposed can be applied to HALT/HASS tests in order to obtain large vibrations and, consequently stress, to identify possible flaws in the design and correct them.

Por décadas, a qualidade de produtos é determinada por testes em ambientes de laboratório, como testes de acelerados de vibração, ciclagem térmica, choque mecânicos ou térmicos, entre outros. Porém, mais recentemente um novo tipo de técnica tem adquirido a confiança de pesquisadores e projetistas. As técnicas conhecidas como HALT (Highly Accelerated Life Testing) e HASS (Highly Accelerated Stress Screening), ou seja, testes acelerados e amplificados que submetem produtos a condições severas, têm mostrado sua importância e eficiência no âmbito da detecção de falha em produtos ainda na fase de produção. Este trabalho tem por objetivo desenvolver e implementar um algoritmo de controle baseado em métodos heurísticos para ser usado em ensaios acelerados usando um Shaker eletrodinâmico. Este controlador deve ser robusto o suficiente para se adequar a possíveis efeitos de ressonância do shaker que podem vir a alterar a dinâmica do sistema, inviabilizando controles tradicionais com parâmetros fixos. Os resultados obtidos através de vários ensaios mostraram que ambos os sistemas de controle são eficientes, pois o erro entre o sinal desejado (tensão mecânica ou aceleração) e os medidos experimentalmente, tendem rapidamente a zero não apresentando sobressinais consideráveis ou erro em regime permanente, tanto para frequência fixa quanto para varredura de frequência. A comparação entre o controlador tradicional PID e o controle heurístico baseado em Lógica Fuzzy, que foram aplicados no shaker eletrodinâmico, comprova que, para mudanças na amplitude do sistema, o controle Fuzzy apresentou menor sobressinal, o que é mais favorável do ponto de vista mecânico. Logo, a metodologia proposta pode ser aplicada para ensaios HALT/HASS com o intuito de obter grandes vibrações e, por conseguinte tensões, para identificar possíveis falhas de projeto e então, poder corrigi-las. / For decades, product quality is determined by environmental tests, such as accelerated vibration tests, thermal cycling, mechanical or thermal shock, and others. However, more recently a new type of test has gained the trust of researchers and designers. Known techniques such as HALT (Highly Accelerated Life Testing) and HASS (Highly Accelerated Stress Screening), or accelerated and amplified testing that submit products to severe conditions have shown their importance in the efficiency and fault detection in products still in production phase. This study aims to develop and implement a control algorithm based on heuristic methods in order to be used in a system of accelerated tests in an electrodynamic shaker. This controller must be robust enough to fit the resonance effects of the shaker that it can change the system dynamic, invalidating traditional controls with fixed parameters. The results obtained through tests showed both control systems are efficient, because the error between desired signal (mechanical stress and acceleration) and the experimentally measured tend rapidly to zero, there aren’t overshoots or steady state errors, both for constant frequency and for sweep frequency. Comparing the PID traditional control and the Logic Fuzzy control, applied in electrodynamic shaker, we proved that to change system amplitude, the fuzzy control presented lower overshoot, that is favorable from the standpoint of mechanical. Therefore, the methodology proposed can be applied to HALT/HASS tests in order to obtain large vibrations and, consequently stress, to identify possible flaws in the design and correct them.

A sewage treatment plant is going to get a station in their plant reconstructed. It is the station where the water is separated from the sludge and then transported out of the plant. This new station is the main area for this project. The project holds two parts, one where the flow losses are examined and the second is where the system curve and pump configurations are explored. The flow losses can be divided into two parts, major and minor losses. Both will be examined in this project and further the distribution between major and minor losses will be studied. Furthermore, to study the station and the pump configuration, a system curve and a pump curve will be established. Depending on the percentage of dry matter in the sludge (3%, 4% and 5%) the viscosity of the sludge will vary. Therefore, different system curves will be obtained depending on the dry matter. At a given pressure increase, the pump curve will tell what power output is needed depending on the flow rate. The result shows that the flow losses will be the highest for the lowest dry matter rate, 3%. The lower the dry matter rate is, higher velocity on the flow can be used in the station. Due to the higher velocity the losses will increase. The system curves for 3% and 4% are similar. But the curve for 5% differs in where the transition from laminar flow to turbulent flow occurs at a higher flow rate.

With the digital systems moving towards higher frequencies, lower operating voltages and higher power, supplying the required current at the right voltage and at the right time to facilitate timely switching of the CMOS circuits becomes increasingly challenging. The board level power supply cannot meet these requirements directly due to the high inductance of the package interconnections. To overcome this problem, several thin film decoupling capacitors have to be placed on the IC or close to the IC in the package. Two approaches were pursued for high-k thin film decoupling capacitors. 1) Low cost sol-gel based thin film capacitors on organic board compatible Cu-foils 2) RF-sputtered thin film capacitors on silicon substrate for silicon compatible processes While sol-gel provides cost effective technology, sputtered ferroelectric devices are more compatible from manufacturing stand point with the existing technology. Nano-crystalline barium titanate and barium strontium titanate film capacitor devices were fabricated and characterized for organic and silicon substrates respectively. Sol-gel barium titanate films were fabricated first on a bare Cu-foil and then transferred to organic board through a standard lamination process. With process optimization and film doping, a capacitance density of 3 µF/cm2 was demonstrated with breakdown voltage greater than 12V. Leakage current characteristics, breakdown voltages, and electrical reliability of the devices were significantly improved through doping of the barium titanate films and modified film chemistry. Films and interfaces were characterized with high resolution electron microscopy, SEM, XRD, and DC leakage measurements. RF sputtering was selected for ferroelectric thin film integration on silicon substrate. Barium strontium titanate (BST) films were deposited on various electrodes sputtered on silicon substrates. The main focus was to improve interface stabilities for high-k thin films on Si to yield large-area defect-free devices. Effect of bottom electrode selection and barrier layers on device yield and performance were investigated carefully. High yield and high device performance was observed for certain electrode and barrier layer combination. A capacitance density up to 1 µF/cm2 was demonstrated with a breakdown voltage above 15 V on large area, 7 mm2, devices. These two techniques can potentially meet mid-high frequency future decoupling requirements.