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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Photocatalysis of aquatic humic substances prior to chlorination

Palmer, Fiona Lorraine January 1998 (has links)
No description available.
2

Quality of control and real-time scheduling : allowing for time-variations in computer control systems

Sanfridson, Martin January 2004 (has links)
The majority of computers around us are embedded in productsand dedicated to perform certain tasks. A specific task is thecontrol of a dynamic system. The computers are ofteninterconnected by communication networks forming a distributedsystem. Vehicles and manufacturing equipment are two types ofmechatronic machines which often host dedicated computercontrol systems. A research problem is how the real-timebehaviour of the computer system affects the application,especially the control of the dynamic system. If the internal or external conditions varies over time, itbecomes difficult to assign a fixed resource reservation thatwill work well in all situations. In general, the more time anapplication gets of a resource, the better its gauged orperceived quality will be. A strategy is to alter the resourcereservation when the condition changes. This can be constructedas a negotiation between competing applications, a method forwhich the termquality of control, QoC, has been coined. Scalability isthe ability to change the structure and configuration of asystem. It promotes evolving systems and a can help manage acomplex product family. An architecture for a QoC middleware ontop of a scalable computer system, has been proposed. As aquality measureof a control application, the well-knownweighted quadratic loss function used in optimal control, hasbeen revised to encompass a subset of the so called timingproperties. The timing properties are the periods and thedelays in the control loop, including time-varying period anddelay. They are the interface between control and computerengineering, from a control engineering viewpoint. The qualitymeasure can be used both offline and on-line given a model ofthe sampled-data system and an appropriate description of thetiming properties. In order to use a computer system efficiently and toguarantee its responsiveness, real-time scheduling is a must.In fixed priority scheduling each task arrives periodically andhas a fixed priority. A task with a high priority can preempt alow priority task and gain access to the resource. Thebest-case response time characterizes the delays in the system,which is useful from a control viewpoint. A new algorithm tocalculate thebest-caseresponsetime has been derived. It is based on ascheduling scenario which yields a recurrence equation. Themodel is dual to the well-known worst-case response timeanalysis. Besides the dynamic fixed priority scheduling algorithm,optimal control usingstatic schedulinghas been studied, assuming a limitedcommunication. In the static schedule, which is constructedpre-runtime, each task is assigned a time window within aschedule repeated in eternity. The optimal scheduling sequenceis sought by optimizing the overall control performance. Aninteresting aspect is that the non-specified control periodfalls out as a result of theoptimal schedule. The time-varying delay is accountedfor in the control design. Keywords:Real-time scheduling, sampled-data control,performance measure, quality of control, limited communication,time-varying delay, jitter.
3

Quality of control and real-time scheduling : allowing for time-variations in computer control systems

Sanfridson, Martin January 2004 (has links)
<p>The majority of computers around us are embedded in productsand dedicated to perform certain tasks. A specific task is thecontrol of a dynamic system. The computers are ofteninterconnected by communication networks forming a distributedsystem. Vehicles and manufacturing equipment are two types ofmechatronic machines which often host dedicated computercontrol systems. A research problem is how the real-timebehaviour of the computer system affects the application,especially the control of the dynamic system.</p><p>If the internal or external conditions varies over time, itbecomes difficult to assign a fixed resource reservation thatwill work well in all situations. In general, the more time anapplication gets of a resource, the better its gauged orperceived quality will be. A strategy is to alter the resourcereservation when the condition changes. This can be constructedas a negotiation between competing applications, a method forwhich the term<i>quality of control</i>, QoC, has been coined. Scalability isthe ability to change the structure and configuration of asystem. It promotes evolving systems and a can help manage acomplex product family. An architecture for a QoC middleware ontop of a scalable computer system, has been proposed.</p><p>As a<i>quality measure</i>of a control application, the well-knownweighted quadratic loss function used in optimal control, hasbeen revised to encompass a subset of the so called timingproperties. The timing properties are the periods and thedelays in the control loop, including time-varying period anddelay. They are the interface between control and computerengineering, from a control engineering viewpoint. The qualitymeasure can be used both offline and on-line given a model ofthe sampled-data system and an appropriate description of thetiming properties.</p><p>In order to use a computer system efficiently and toguarantee its responsiveness, real-time scheduling is a must.In fixed priority scheduling each task arrives periodically andhas a fixed priority. A task with a high priority can preempt alow priority task and gain access to the resource. Thebest-case response time characterizes the delays in the system,which is useful from a control viewpoint. A new algorithm tocalculate the<i>best-caseresponse</i>time has been derived. It is based on ascheduling scenario which yields a recurrence equation. Themodel is dual to the well-known worst-case response timeanalysis.</p><p>Besides the dynamic fixed priority scheduling algorithm,optimal control using<i>static scheduling</i>has been studied, assuming a limitedcommunication. In the static schedule, which is constructedpre-runtime, each task is assigned a time window within aschedule repeated in eternity. The optimal scheduling sequenceis sought by optimizing the overall control performance. Aninteresting aspect is that the non-specified control periodfalls out as a result of the<i>optimal schedule</i>. The time-varying delay is accountedfor in the control design.</p><p><b>Keywords:</b>Real-time scheduling, sampled-data control,performance measure, quality of control, limited communication,time-varying delay, jitter.</p>
4

Preliminary Hydrogen Sulfide Emission Factors and Emission Models for Wastewater Treatment Plant Headworks

Sengupta, Amitdyuti 16 May 2014 (has links)
Generation of hydrogen sulfide (H2S) is a common phenomenon from wastewater collection, transport, and treatment processes. Impacts of H2S emissions from wastewater include corrosion and reduction in the service life of wastewater infrastructure, odor nuisance in the community, and health impacts on wastewater operations and maintenance personnel (Neilsen, et al. WEFTEC 2006). Conventional odor control studies performed by municipalities to design their individual odor/corrosion control strategies largely depend on establishing a dilution to detection threshold (D/T) ratio and ascertaining the recognition threshold (R/T) for air samples collected from the study area. These conventional odor studies based on grab samples using R/T and D/T technique using a few days of data have a number of limitations and potentially lead to inaccurate conclusions. However, H2S emission studies using continuous air monitoring is expensive and time consuming. The objective of this research is to understand the feasibility of utilizing emission factors as a tool to predict hydrogen sulfide emissions from headworks of four different Jefferson Parish, Louisiana wastewater treatment plants (WWTP). Proposed model(s) developed for predicting H2S emission factors that depend on wastewater parameters should be convenient for the municipalities to use as the data required is monitored routinely. Use of H2S emission models should assist rapid identification of H2S emission hot spots, optimize H2S control strategies, predict potential health risks, prevent community odor nuisance, and ascertain infrastructure corrosion. This dissertation attempts to; i) develop a research methodology, ii) identify instruments required, iii) generate emission factor ranges and compare their sensitivity to wastewater parameters, iv) generate preliminary empirical emission models based on flow treated, population serviced and area served by a treatment plant for each sampling location and v) provide a roadmap for future research opportunities to refine the models generated as part of this dissertation. Key words: emission model, emission factor, emission ranges, hydrogen sulfide, odor control, air quality, wastewater treatment.
5

On the development of control systems technology for fermentation processes

Loftus, John January 2017 (has links)
Fermentation processes play an integral role in the manufacture of pharmaceutical products. The Quality by Design initiative, combined with Process Analytical Technologies, aims to facilitate the consistent production of high quality products in the most efficient and economical way. The ability to estimate and control product quality from these processes is essential in achieving this aim. Large historical datasets are commonplace in the pharmaceutical industry and multivariate methods based on PCA and PLS have been successfully used in a wide range of applications to extract useful information from such datasets. This thesis has focused on the development and application of novel multivariate methods to the estimation and control of product quality from a number of processes. The document is divided into four main categories. Firstly, the related literature and inherent mathematical techniques are summarised. Following this, the three main technical areas of work are presented. The first of these relates to the development of a novel method for estimating the quality of products from a proprietary process using PCA. The ability to estimate product quality is useful for identifying production steps that are potentially problematic and also increases process efficiency by ensuring that any defective products are detected before they undergo any further processing. The proposed method is simple and robust and has been applied to two separate case studies, the results of which demonstrate the efficacy of the technique. The second area of work concentrates on the development of a novel method of identifying the operational phases of batch fermentation processes and is based on PCA and associated statistics. Knowledge of the operational phases of a process can be beneficial from a monitoring and control perspective and allows a process to be divided into phases that can be approximated by a linear model. The devised methodology is applied to two separate fermentation processes and results show the capability of the proposed method. The third area of work focuses on undertaking a performance evaluation of two multivariate algorithms, PLS and EPLS, in controlling the end-point product yield of fermentation processes. Control of end-point product quality is of crucial importance in many manufacturing industries, such as the pharmaceutical industry. Developing a controller based on historical and identification process data is attractive due to the simplicity of modelling and the increasing availability of process data. The methodology is applied to two case studies and performance evaluated. From both a prediction and control perspective, it is seen that EPLS outperforms PLS, which is important if modelling data is limited.
6

Uso da espectrometria de massas como ferramenta metabolômica e controle de qualidade de óleos vegetais e gorduras animais / Use of mass spectrometry as a metabolomic tool and quality control of vegetable oils and animal fats

Riccio, Maria Francesca 03 November 2011 (has links)
Orientador: Rodrigo Ramos Catharino / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-18T04:45:53Z (GMT). No. of bitstreams: 1 Riccio_MariaFrancesca_M.pdf: 1073402 bytes, checksum: ad216531a7e88603fc492ee5c702fd1f (MD5) Previous issue date: 2011 / Resumo: Este trabalho direcionou-se ao controle de qualidade de óleos vegetais e gorduras animais pelo emprego de análise de baixa massa molecular pela técnica EASI-MS utilizando a ferramenta metabolômica. As matérias-primas graxas (óleos e gorduras vegetais e animais) e os produtos sintetizados a partir destes insumos são misturas complexas, com aplicações e valores agregados variados como por exemplo para a nutrição humana, aplicações industriais na produção de lubrificantes, biodiesel, plasticidas, surfactantes, entre outros. As técnicas disponíveis como Cromatografia gasosa (GC) com detector de ionização de chama (FID) ou acoplada a um espectrômetro de massas (GC-MS) tem sido as técnicas mais utilizadas para caracterizar óleos e gorduras, através da determinação da composição de ácidos graxos. Como a caracterização da composição graxa destas matrizes são muitas vezes restritas, exigindo a necessidade de procedimentos laboriosos como extrações, purificações que requerem muito tempo utilizamos neste trabalho uma recente técnica de ionização ambiente de espectrometria de massas: EASI-MS (easy ambient sonic-spray ionization mass spectrometry) na caracterização de óleos vegetais e gorduras animais que dispensa o emprego de processos de derivatização química e a separação cromatográfica. Neste trabalho aplicamos a metabolômica para elucidação de um conjugado de marcadores taxonômicos de óleos nunca observados ou analisados em conjunto antes, principalmente ácidos graxos e bifenóis os quais podem ser extraídos de maneira simples e eficaz. Para a caracterização dos componentes existentes no metaboloma de óleos de origem vegetal e animal e para a caracterização de azeites de oliva de diferentes procedências, uma simples extração com uma solução hidroalcoólica foi utilizada. O extrato foi adicionados à uma superfície de vidro para dessa forma, serem injetados para dentro do equipamento de massas e então analisados. O equipamento utilizado foi um Q-TrapTM utilizando uma fonte de EASI construída por pesquisadores do Laboratório ThoMSon de espectrometria de massas (IQ/UNICAMP). Os espectros de massas obtidos demonstraram a presença de ácidos graxos livres além de bifenóis característicos de cada tipo de óleo ou gordura analisado. A presença na mesma análise (espectro) demonstrou que mesmo para amostras complexas, a técnica se mostra aplicável para a identificação, caracterização e controle de qualidade de maneira inequívoca para óleos e gorduras / Abstract: This work is directed to quality control of vegetable oils and animal fats by the use of low molecular analysis of the EASI-MS technique using the metabolomics tool. Raw materials greases (oils and vegetable and animal fats) and the products synthesized from these inputs are complex mixtures, with varying applications and value added such as for human nutrition, industrial applications in the lubrificants production, biodiesel, plasticity, surfactants, among others. The available techniques such as chromatography (GC) with flame ionization detector (FID) and coupled to a mass spectrometer (GC-MS) has been the most widely used techniques to characterize oils and fats by determining the fatty acid composition. To characterize the grease composition of these matrices are often restricted, requiring the need of laborious procedures such as extractions, purifications that require much time, in this work we used a recent technique ambient ionization mass spectrometry: EASI-MS (Easy ambient sonic-spray ionization mass spectrometry) in the characterization of vegetable oils and animal fats does not require the use of chemical derivatization procedures and chromatographic separation. In this work we have applied metabolomics to elucidate a combination of taxonomic markers oils never observed or analyzed together before, mainly fatty acids and biphenols which can be extracted in a simple and effective process. To characterize the metabolome of existing components in vegetable oils and animal and for the characterization of olive oils from different sources, a simple extraction with a water-methanol solution was used. The extract was added to a glass surface to thereby be injected into the spectrometer and then analyzed. The equipment used was a Q-TrapTM using a source of EASI built by researchers at the Thomson Laboratory of mass spectrometry (Institute of Chemistry / UNICAMP). The mass spectra obtained showed the presence of free fatty acids besides biphenols characteristic of each type of oil or fat analyzed. The presence in the same analysis (spectrum) showed that even for complex samples, the technique proves to be applicable to the identification, characterization and quality control unequivocally for oils and fats / Mestrado / Ciencias Biomedicas / Mestre em Ciências Médicas
7

Characterisation of groundwater in mainly old and closed landfill sites

Gajree, Meenu January 1999 (has links)
A study is made of the use of chemical analysis of groundwater samples to assess groundwater quality. Samples from forty-seven boreholes within and around ten landfill sites in the London Borough of Hounslow were analysed. Most of the landfill sites studied were filled prior to the implementation of the Control of Pollution Act 1974 and were not designed with environmental protection in mind. Boreholes were tested for methane, carbon dioxide and groundwater samples were analysed for electrical conductivity (EC), ammonium nitrogen (NI14-N), COD, TOC, Cl-, NO3, SO42-, Na+, K+, Ca2+, Ni2+, Cu2+, Pb2+, oxidation - reduction - potential (ORP) and pH. The first ten of these analytical parameters were considered for groundwater quality assessment and the most important selected for more detailed study namely CH4, C02, EC, NH4-N, COD and TOC. Pollution ratings are allocated on the basis of single pollutant analytical data and averaged for each of the bore hole samples. Goodness of fit values between the single analyte values and the average data were calculated and no set of single analyte data was found to provide good groundwater quality assessment. A series of formulae combining the six analyte parameters was considered and the data evaluated by goodness of fit calculations to provide an effective means of assessing groundwater quality. The ratings obtained from the best formula are compared with historical broad band classification of landfill sites and show how sites must be assessed on the basis of samples taken from within the site and not around the perimeter. The production of acetic acid in the acetogenic phase of landfill reactions will increase the leachability and mobility of many metal pollutants and particularly of lead. Studies on the leachability of lead in acetic acid media show how lead solubility is increased in acetic acid media by the formation of triacetatolead(II) species, Pb(CH3CO2)3-.
8

Zavedení SPC ve výrobním procesu / Implementation of SPC into the manufacturing process

Simandl, Martin January 2019 (has links)
The diploma thesis focuses on the introduction of statistical process control in selected manufacturing company XYZ. It is divided into a theoretical and a practical part, while the theoretical part deals with theoretical knowledge of SPC methodology and quality management. The content of the practical part is the design and implementation of the measuring and evaluation station, which will be used for statistical control of the SPC process, into the emerging production of chip machining.
9

Zavedení SPC ve výrobním procesu / Implementation of SPC into the manufacturing process

Simandl, Martin January 2019 (has links)
The diploma thesis focuses on the introduction of statistical process control in selected manufacturing company XYZ. It is divided into a theoretical and a practical part, while the theoretical part deals with theoretical knowledge of SPC methodology and quality management. The content of the practical part is the design and implementation of the measuring and evaluation station, which will be used for statistical control of the SPC process, into the emerging production of chip machining.
10

Réseaux de communication et applications de contrôle-commande / Communication Networks and Process Control Applications

Nguyen, Xuan hung 15 December 2011 (has links)
Cette thèse se situe dans le domaine des Systèmes Commandés en Réseaux, systèmes pluridisciplinairesqui connaissent un grand développement dans le contexte technologique actuel etqui introduisent de nouveaux problèmes de recherche, en particulier, pour les communautés Automatiqueet Réseau de Communication. L’objectif est de montrer l’intérêt de considérer un lienbidirectionnel entre la Qualité de Contrôle (QdC) (stabilité et performance des applications decontrôle-commande) et la Qualité de Service (QdS) (retards dans les transmissions) en se focalisantsur les réseaux locaux et plus particulièrement sur l’ordonnancement des trames dans la souscouche MAC où on considère des protocoles MAC de type CSMA.Notre travail se situe tout d’abord dans le cadre du réseau CAN où nous faisons trois propositions.La première proposition consiste en des solutions de QdS pour des applications decontrôle-commande sur la base du concept de priorité hybride, pour l’ordonnancement de trames,dans laquelle nous définissons une partie priorité dynamique qui dépend d’un paramètre de QdC.Ceci permet de réaliser une relation QdC→QdS. La deuxième proposition consiste en des solutionsde QdC par une méthode de compensation de retard (maintenance des pôles dominants)ce qui permet de réaliser une relation QdS→QdC. La troisième proposition consiste à réaliserune relation QdC⇋QdS qui assure lors de l’implantation de plusieurs applications, une propriétéd’équité comportementale. Nous abordons ensuite le cadre particulier des réseaux locaux sans filoù, d’une part, nous définissons des protocoles MAC de type CSMA sans collision sur la basede priorités et, d’autre part, nous montrons la faisabilité des idées développées dans le cadre duréseau CAN / This thesis is in the field of Networked Controlled Systems, which are multidisciplinary systemsand which experience a great development in the context of the current technology andintroduce new research problems, particularly for the communities of Automatic Control andCommunication Network. The aim is to show the interest in considering a bidirectional link betweenthe Quality of Control (QoC) (stability and performance of process control applications) andQuality of Service (QoS) (delays in the transmissions) and to focus on Local Area Networks and,more particularly, on the scheduling of frames in the MAC layer in which we consider CSMAMAC protocols.Our work first concerns a CAN network where we have three proposals. The first proposalconsists of solutions for QoS, for process control applications, which are based on the conceptof hybrid priority for the frame scheduling in which we define a dynamic priority part which dependson a QoC parameter. This allows to implement a relation QoC→QoS. The second proposalconsists of QoC solutions by using a compensation method for time delays (maintenance of dominantpoles) which allows to implement a relation QoS→QoC. The third proposal consists inimplementing a relation QoS⇋QoC that ensures, for the implementation of several applications,a fairness property. We then discuss the specific context of Wireless LANs, where, on the onehand, we define collision-free CSMA MAC protocols on the basis of priorities and, on the otherhand, we show the feasibility of the ideas developed in the CAN network

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