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SYSTEM IDENTIFICATION OF A WASTE-FIRED CFB BOILER : Using Principal Component Analysis (PCA) and Partial Least Squares Regression modeling (PLS-R)Hassling, Andreas, Flink, Simon January 2017 (has links)
Heat and electricity production along with waste management are two modern day challenges for society. One of the possible solution to both of them is the incineration of household waste to produce heat and electricity. Incineration is a waste-to-energy treatment process, which can reduce the need for landfills and save the use of more valuable fuels, thereby conserving natural resources. This report/paper investigates the performance and emissions of a municipal solid waste (MSW) fueled industrial boiler by performing a system identification analysis using Principle Component Analysis (PCA) and Partial Least Squares Regression (PLS-R) modeling. The boiler is located in Västerås, Sweden and has a maximum capacity of 167MW. It produces heat and electricity for the city of Västerås and is operated by Mälarenergi AB. A dataset containing 148 different boilers variables, measured with a one hour interval over 2 years, was used for the system identification analysis. The dataset was visually inspected to remove obvious outliers before beginning the analysis using a multivariate data analysis software called The Unscrambler X (Version 10.3, CAMO Software, Norway). Correlations found using PCA was taken in account during the PLSR modelling where models were created for one response each. Some variables had an unexpected impact on the models while others were fully logical regarding combustion theory. Results found during the system analysis process are regarded as reliable. Any errors may be due to outlier data points and model inadequacies. Read more
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Monitoramento em linha e em tempo real do diâmetro médio das partículas e dos teores de não voláteis e monômero durante a polimerização em emulsão usando espectroscopia NIR. / In-line real-time monitoring of average particle size and solids monomer contents during emulsion polymerization using NIR spectroscopy.Silva, Wandeklébio Kennedy da 02 April 2009 (has links)
A técnica de polimerização em emulsão tem sido usada cada vez mais na indústria de tintas, resinas, plásticos, entre outros. Esse crescimento se deve as razões ambientais (uma vez que se utiliza água como fase contínua desta reação), também a versatilidade e a capacidade de produzir látex com diferentes propriedades para diferentes aplicações. Polímeros em emulsão são produtos por processo, isto é, suas propriedades são definidas durante a polimerização. Por isso, é importante o adequado monitoramento da reação de modo a permitir o controle das propriedades desejadas. A técnica de espectroscopia na região do infravermelho próximo (NIR), combinada com o uso de fibras óticas, é muito promissora para o monitoramento multivariável, em linha e em tempo real do processo de polimerização. O objetivo deste trabalho foi o de estudar o uso de espectroscopia NIR para o monitoramento em linha e em tempo real das concentrações de monômero e de não- voláteis (conhecido também como teor de sólidos) e da evolução do tamanho médio das partículas de látex (Dp) durante a reação de polimerização em emulsão de metacrilato de metila (MMA), em escala de laboratório e processo semi-batelada. Os modelos de calibração para estas variáveis foram obtidos experimentalmente empregando o método de regressão por mínimos quadrados parciais, PLS. Os resultados obtidos confirmaram algumas regiões espectrais do NIR indicadas em literatura como sendo adequadas na predição de monômero e Dp e revelaram -1 comportamentos espectrais ainda não explicados na região entre 10.475 e 13.000 cm , relacionados às variações no tamanho das partículas. Os resultados mostram também que é possível monitorar em linha e em tempo real a evolução do Dp e dos teores de monômero (MMA) e de não voláteis, simultaneamente em um único instrumento, utilizando modelos de calibração com bandas espectrais e pré-tratamentos distintos. / Emulsion polymerization is a largely and increasingly used technique in industrial production of paints, resins, plastics among others. This increase is due to environmental reasons (since water, rather than organic solvents is used as dispersing medium), as well as to the versatility and capacity of producing products with different properties for different applications. Emulsion polymers are products by process, i.e., the properties are mainly defined during the polymerization process. Thus, the adequate process monitoring is important for achieving the target properties. The NIR spectroscopy combined with optical fibers is a promising technique for the task of multivariable, real-time, in-line monitoring of polymerization processes. The aim of this work is the study of use of NIR spectroscopy for in-line, real time monitoring of the monomer and solids content, as well as the evolution of average size of the polymer particles (Dp), during semi-batch emulsion polymerization of methyl methacrylate in laboratory reactor. The calibration models for each of the monitored variables were obtained by applying the partial least squares regression method (PLS). The results confirmed that some NIR spectral ranges recommended in the literature are appropriate for the prediction of monomer content and Dp, and that there are spectral -1 . The results behaviors not yet explained in the region between 10475 and 13000cm also show that the in-line, the changes in Dp, monomer and polymer content can be simultaneously monitored in-line and in real time by NIR spectroscopy by using calibration models based on adequate spectral regions and distinct data pretreatments. Read more
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Improving collaborative forecasting performance in the food supply chainEksoz, Can January 2014 (has links)
The dynamic structure of the Food Supply Chain (FSC) distinguishes itself from other supply chains. Providing food to customers in a healthy and fresh manner necessitates a significant effort on the part of manufacturers and retailers. In practice, while these partners collaboratively forecast time-sensitive and / or short-life product-groups (e.g. perishable, seasonal, promotional and newly launched products), they confront significant challenges which prevent them from generating accurate forecasts and conducting long-term collaborations. Partners’ challenges are not limited only to the fluctuating demand of time-sensitive product-groups and continuously evolving consumer choices, but are also largely related to their conflicting expectations. Partners’ contradictory expectations mainly occur during the practices of integration, forecasting and information exchange in the FSC. This research specifically focuses on the Collaborative Forecasting (CF) practices in the FSC. However, CF is addressed from the manufacturers’ point of view, when they collaboratively forecast perishable, seasonal, promotional and newly launched products with retailers in the FSC. The underlying reasons are that while there is a paucity of research studying CF from the manufacturers’ standpoint, associated product-groups decay at short notice and their demand is influenced by uncertain consumer behaviour and the dynamic environment of FSC. The aim of the research is to identify factors that have a significant influence on the CF performance. Generating accurate forecasts over the aforementioned product-groups and sustaining long-term collaborations (one year or more) between partners are the two major performance criteria of CF in this research. This research systematically reviews the literature on Collaborative Planning, Forecasting and Replenishment (CPFR), which combines the supply chain practices of upstream and downstream members by linking their planning, forecasting and replenishment operations. The review also involves the research themes of supply chain integration, forecasting process and information sharing. The reason behind reviewing these themes is that partners’ CF is not limited to forecasting practices, it also encapsulates the integration of chains and bilateral information sharing for accurate forecasts. A single semi-structured interview with a UK based food manufacturer and three online group discussions on the business oriented social networking service of LinkedIn enrich the research with pragmatic and qualitative data, which are coded and analysed via software package QSR NVivo 9. Modifying the results of literature review through the qualitative data makes it possible to develop a rigorous conceptual model and associated hypotheses. Then, a comprehensive online survey questionnaire is developed to be delivered to food manufacturers located in the UK & Ireland, North America and Europe. An exploratory data analysis technique using Partial Least Squares (PLS) guides the research to analyse the online survey questionnaire empirically. The most significant contributions of this research are (i) to extend the body of literature by offering a new CF practice, aiming to improve forecast accuracy and long-term collaborations, and (ii) to provide managerial implications by offering a rigorous conceptual model guiding practitioners to implement the CF practice, for the achievement of accurate forecasts and long-term collaborations. In detail, the research findings primarily emphasise that manufacturers’ interdepartmental integration plays a vital role for successful CF and integration with retailers. Effective integration with retailers encourages manufacturers to conduct stronger CF in the FSC. Partners’ forecasting meetings are another significant factor for CF while the role of forecasters in these meetings is crucial too, implying forecasters’ indirect influence on CF. Complementary to past studies, this research further explores the manufacturers’ various information sources that are significant for CF and which should be shared with retailers. It is also significant to maintain the quality level of information whilst information is shared with retailers. This result accordingly suggests that the quality level of information is obliquely important for CF. There are two major elements that contribute to the literature. Firstly, relying on the particular product-groups in the FSC and examining CF from the manufacturers’ point of view not only closes a pragmatic gap in the literature, but also identifies new areas for future studies in the FSC. Secondly, the CF practice of this research demonstrates the increasing forecast satisfaction of manufacturers over the associated product-groups. Given the subjective forecast expectations of manufacturers, due to organisational objectives and market dynamics, demonstrating the significant impact of the CF practice on the forecast satisfaction leads to generalising its application to the FSC. Practitioners need to avail themselves of this research when they aim to collaboratively generate accurate forecasts and to conduct long-term collaborations over the associated product-groups. The benefits of this research are not limited to the FSC. Manufacturers in other industries can benefit from the research while they collaborate with retailers over similar product-groups having a short shelf life and / or necessitating timely and reliable forecasts. In addition, this research expands new research fields to academia in the areas of the supply chain, forecasting and information exchange, whilst it calls the interest of academics to particular product-groups in the FSC for future research. Nevertheless, this research is limited to dyad manufacturer-retailer forecast collaborations over a limited range of product-groups. This is another opportunity for academics to extend this research to different types of collaborations and products. Read more
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Continuity of care and its effect on patients' motivation to initiate and maintain cardiac rehabilitationPayne, Liz January 2015 (has links)
Background: Despite national guidance and empirical support for its clinical and cost-effectiveness, cardiac rehabilitation (CR) is underused. Only 44% of patients go to CR, with angioplasty (Percutaneous Coronary Intervention; PCI) patients being least likely to attend (31% of 87,000). Aim: To investigate the relationship between ‘continuity of care’ and patients’ motivation towards CR, through the lens of self-determination theory, and develop a model to inform service design to increase CR uptake and adherence. Methods: A mixed methods approach was used. In Study 1, a theoretical model of continuity of care and motivational antecedents was tested with a cross-sectional sample of 107 PCI patients. To further explore interactions between continuity of care and motivation towards cardiac rehabilitation, a Critical Interpretive Synthesis of the extant literature was used in Study 2, and focus groups were carried out with patients and service providers in Study 3. Results: In Study 1, continuity of care positively predicted patients’ autonomous motivation towards CR, and this was partially mediated by autonomy support. Autonomy support was associated with CR attendance. In Studies 2 and 3, aspects of continuity of care with positive effects on attendance were identified. These included timely, appropriate information provision, relationships bridging CR phases and settings, and continuing management strategies incorporating trusting, warm staff-patient relationships, and positive encouragement and feedback about progress. The SDT constructs of autonomy support, need satisfaction, internalisation and quality of motivation helped to explain positive and negative influences of continuity on attendance. Conclusion: Continuity of care has a positive effect on patients’ motivation towards CR. The most enduring motivation comes from delivering continuity of care in an autonomy-supportive and competence-supportive way. Longitudinal research is needed to compare how need-supportive and need-thwarting aspects of continuity of care affect CR attendance and adherence, and whether these relationships are influenced by need satisfaction and need frustration. Read more
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Proposição de uma abordagem para classificação, projeção e controle da obsolecência de inventários apoiada em ferramentas multivariadas / Proposition of an approach for the classification, projection and control of inventory obsolescence supported by multivariate toolsBurgel, Evandro January 2018 (has links)
A obsolescência de estoques é um evento recorrente nas organizações, demandando o uso de métodos que identifiquem o inventário excessivo antes dele tornar-se obsoleto. Este artigo propõe um método para classificação, projeção e controle da obsolescência de inventários ao longo do tempo, com o objetivo de reduzir o risco de obsolescência ou deterioração futura. A abordagem proposta possui cinco passos, sendo os quatro primeiros dedicados a identificação dos fatores que contribuem para a obsolescência e/ou deterioração do Inventário, a classificação do estoque em categorias e faixas de idade através da análise discriminante, a seleção de variáveis em contexto de PLS, a modelagem de regressão para projeção da idade do inventário ao longo do tempo e a definição de diretrizes para redução do risco de obsolescência. O quinto passo do método utiliza o conceito do ciclo PDCA buscando a melhoria contínua do processo e dos resultados. Na aplicação em dois estudos de caso em indústrias de bens de consumo, o método previu adequadamente o montante do inventário por faixa de idade e o risco de obsolescência ou deterioração do inventário em um horizonte de seis meses. / Inventory obsolescence is a prominent phenomenon in organizations, requiring the use of methods that identify excessive inventory before it becomes obsolete. This paper proposes a method to classify, forecast and control the obsolescence of inventories over time in order to reduce the risk of future obsolescence or deterioration. The proposed approach has five steps, the first four of which are dedicated to identifying the factors that contribute to the obsolescence and/or deterioration of the Inventory, the classification of the inventory into categories and age ranges through discriminant analysis, the selection of variables in the context of PLS, regression modeling to forecast the age of inventory over time and the definition of guidelines for reducing the risk of obsolescence. The fifth step of the method uses the concept of the PDCA cycle seeking for the continuous improvement of process and results. In the application in two case studies in consumer goods industries, the method predicted the amount of inventory by age range and the risk of obsolescence or deterioration of the inventory over a six-month horizon. Read more
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Modellering och styrning av flis till en sulfatkokare / Modelling and control of wooden chips to a sulphate digesterOhlsson, Staffan January 2005 (has links)
<p>At the Skoghall pappermill, sulphatepaper pulp is produced in a continuous digester originally from 1969. To be able to maintain a high level of production there is a need for a process with few disturbances. Variations in how well the wooden chips are packed in the digester is one form of disturbance. Today there are no available measurements on how well the chips are packed. Instead this is regarded as being constant. </p><p>The variation in the so called bulk density of the chips is mainly due to variations in the percentage with small dimensions. Chips are classified in relation to their size and one of the smallest classes is referred to as pin chips. These are believed to have a big impact on the bulk density. The amount of pin chips fluctuate more then the other classes, there by causing disturbances. </p><p>The Skoghall pappermill has invested in a ScanChip. This is an instrument that measures the dimensions of the chips optically. ScanChip presents figures on chip quality, including a measurement of the bulk density. However, it has been shown that this measurement is not valid for the Skoghall pappermill. By using data from ScanChip a model that predicts how well the chips are packed has been devised. This value is the bulk density divided by the basic density. The model has proved to yield good results, despite a relatively small amount of data. </p><p>A theoretical value of the amount of produced pulp has been computed based on the revolutions of the production screw that feeds chips into the digester. This value takes in consideration how well the chips are packed. The value has shown great similarities with the empirical measurements that are used today. A simulation during one month has shown that differences in the mixture of chips have effected the measurement of produced pulp with up to 7 ton/h. </p><p>Chips are stored in open pile storages before they are being used in the process of transforming them into pulp. Four screws are used to move chips from the piles to conveyer belts. It has been shown in work done previously, that the movement of the screws contributes to variations in the amount of pin chips measured by ScanChip. </p><p>During the work with this master’s thesis I have found that there are variations in the piles that make it difficult to predict the amount of pin chips accordingly. However by filtering the measurements of pin chips to remove these variations, the results are improved. A new way of controlling the movements of the screws was operational on the 10 of March and this improved the results. </p><p>The direction in which the screws are moving influence the speed of the screws, mainly in the pile with the so called sawmill chips. By changing the amount of chips that each screw puts out, the differences in speed have been reduced. The mixtures found in the two piles are not completely homogenous. There are a greater amount of pin chips in the northern parts compared with the southern parts. This could be an effect of the wind direction, and will still cause variations.</p> Read more
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Plant Condition Measurement from Spectral Reflectance Data / Växttillståndsmätningar från spektral reflektansdataJohansson, Peter January 2010 (has links)
<p>The thesis presents an investigation of the potential of measuring plant condition from hyperspectral reflectance data. To do this, some linear methods for embedding the high dimensional hyperspectral data and to perform regression to a plant condition space have been compared. A preprocessing step that aims at normalized illumination intensity in the hyperspectral images has been conducted and some different methods for this purpose have also been compared.A large scale experiment has been conducted where tobacco plants have been grown and treated differently with respect to watering and nutrition. The treatment of the plants has served as ground truth for the plant condition. Four sets of plants have been grown one week apart and the plants have been measured at different ages up to the age of about five weeks. The thesis concludes that there is a relationship between plant treatment and their leaves' spectral reflectance, but the treatment has to be somewhat extreme for enabling a useful treatment approximation from the spectrum. CCA has been the proposed method for calculation of the hyperspectral basis that is used to embed the hyperspectral data to the plant condition (treatment) space. A preprocessing method that uses a weighted normalization of the spectrums for illumination intensity normalization is concluded to be the most powerful of the compared methods.</p> Read more
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Statut de la faillite en théorie financière : approches théoriques et validations empiriques dans le contexte françaisBen Jabeur, Sami 27 May 2011 (has links) (PDF)
Dans la conjoncture économique actuelle un nombre croissant de firmes se trouvent confrontées à des difficultés économiques et financières qui peuvent, dans certains cas, conduire à la faillite. En principe, les difficultés ne surviennent pas brutalement, en effet, avant qu'une entreprise soit déclarée en faillite, elle est confrontée à des difficultés financières de gravité croissante : défaut de paiement d'une dette, insolvabilité temporaire, pénurie de liquidité, etc. L'identification des causes de la défaillance n'est pas évidente, puisqu'on ne saurait énumérer de manière limitative les facteurs qui la provoquent. Les causes sont multiples et leur cumul compromet d'autant plus la survie de l'entreprise. L'importance de ce phénomène et son impact sur l'ensemble de l'économie justifie le besoin de le comprendre, l'expliquer en analysant les causes et les origines. L'objectif de notre étude est de classer les entreprises en difficulté selon leur degré de viabilité et de comprendre les causes de la dégradation de leur situation. Nous effectuerons une comparaison entre trois modèles (Analyse discriminante linéaire, le modèle Logit et la régression PLS) ce qui nous permettra à partir des taux de bon classement obtenus, de choisir le meilleur modèle tout en précisant l'origine et les causes de ces défaillances. Read more
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Near infrared and skin impedance spectroscopic in vivo measurements on human skin : development of a diagnostic tool for skin cancerBodén, Ida January 2011 (has links)
Every year approximately 2800 Swedes are diagnosed with malignant melanoma, the form of cancer that is most rapidly increasing in incidence in the Western world. The earlier we can identify and diagnose a malignant melanoma, the better is the prognosis. In Sweden, 155 000 benign naevi, harmless skin tumours or moles, are surgically excised each year, many of them because melanoma cannot be dismissed by non-invasive methods. The excisions result in substantial medical costs and cause unrest and suffering of the individual patient. For untrained physicians, it is often difficult to make an accurate diagnosis of melanoma, thus a tool that could help to strengthen the diagnosis of suspected melanomas would be highly valuable. This thesis describes the development and assessment of a non-invasive method for early skin cancer detection. Using near infrared (NIR) and skin impedance spectroscopy, healthy and diseased skin of various subjects was examined to develop a new instrument for detecting malignant melanoma. Due to the complex nature of skin and the numerous variables involved, the spectroscopic data were analysed multivariately using Principal Component Analysis (PCA) and partial leas square discriminant analysis (PLS-DA). The reproducibility of the measurements was determined by calculating Scatter Values (SVs), and the significance of separations between overlapping groups in score plots was determined by calculating intra-model distances. The studies indicate that combining skin impedance and NIR spectroscopy measurements adds value, therefore a new probe-head for simultaneous NIR and skin impedance measurements was introduced. Using both spectroscopic techniques it was possible to separate healthy skin at one body location from healthy skin at another location due to the differences in skin characteristics at various body locations. In addition, statistically significant differences between overlapping groups of both age and gender in score plots were detected. However, the differences in skin characteristics at different body locations had stronger effects on the measurements than both age and gender. Intake of coffee and alcohol prior to measurement did not significantly influence the outcome data. Measurements on dysplastic naevi were significantly separated in a score plot and the influence of diseased skin was stronger than that of body location. This was confirmed in a study where measurements were performed on 12 malignant melanomas, 19 dysplastic naevi and 19 benign naevi. The malignant melanomas were significantly separated from both dysplastic naevi and benign naevi. Overall, the presented findings show that the instrument we have developed provides fast, reproducible measurements, capable of distinguishing malignant melanoma from dysplastic naevi and benign naevi non-invasively with 83% sensitivity and 95% specificity. Thus, the results are highly promising and the instrument appears to have high potential diagnostic utility. Read more
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Methodological aspects of unspecific building related symptoms researchGlas, Bo January 2010 (has links)
This thesis deals with methological issues in the study of chemical exposure and sick building syndrome (SBS). SBS is a combination of general, mucosal and skin symptoms that some people experience when staying in specific buildings. The aim was to find chemical patterns associated with SBS, but also to address methological problems in such study. The plan was to conduct a case-control study comparing the two groups’ chemical exposure, where cases were defined as those having at least one general, one mucosal and one skin symptom each week the last three months. For the planning it was necessary to know if cases and controls could be selected from the same building. If everyone in a building have the same chemical exposure it is no use to compare exposure between two persons at the same workplace. In the first paper exposure to more than 100 compounds is compared between 79 participants working in eight buildings. It was found that for the majority of compounds the variation in exposure was larger within buildings than between buildings, which means that cases and controls could be allowed to work in the same building. The second paper is a comparison of three adsorbents usability in finding differences in chemical exposure between SBS cases and controls. This was done by using chemometrical methods but comparisons of sampled amounts, blank values and reproducibility were also done. Tenax TA was found to be the best adsorbent, hence used in the case-control study. In recent years ozone and ozone reaction products with unsaturated volatile organic compounds (VOCs) has been in focus. Nitrogen dioxide is another gas affecting oxidation of reactive VOCs. Formaldehyde is an irritant formed when unsaturated VOCs are oxidised, and in some studies a relation with SBS has been found. In paper three the relation between personal exposure to formaldehyde, nitrogen dioxide, ozone, terpenes and SBS has been investigated among more than 200 office workers in a case control study in Umeå and Vasa. Cases (based on symptoms during the week of measurements) had lower ozone exposure than controls. No further associations were found at present exposure levels. A planed analysis of relations to VOCs could not be done due to analytical problems, and problems due to difficulties with consistent identification of compounds in a very large data set. These problems are further discussed in the thesis. In the case-control, study participants answered questionnaires about symptoms during "the past three months", "right now" (when answering the questionnaire), and during the week of exposure measurements. In the fourth paper the stability of symptoms were compared by answers at different occasions. It was found that the case/control concept was as stable as individual symptoms. More participants with atopic disease and those 41 years old or younger changed class compared with those without atopic disease and older participants. Measurement activities appeared to make participants report more symptoms. Fatigue, dry eyes and dry skin are suggested to be symptoms with strongest, and illness/dizziness to be weakest association with IAQ. / KLUCK-projektet Read more
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