Dissertations / Theses on the topic 'Controls strategies'
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Yuan, Bau-San. "Adaptive strategies for controls of flexible arms." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/17683.
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Washington, Melissa M. "Strategies for Improving Profitability Through Effective Internal Controls." ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/5670.
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Between 2007 and 2009, the United States experienced a financial crisis. Many businesses experienced difficulties obtaining funds for projects and working capital due to the great recession. As a result, many business owners filed for bankruptcy. The purpose of this multiple case study was to explore strategies that some small business owners in the construction industry used when implementing internal control processes to improve profits. The study population entailed 6 individuals in the southeast region of the United States who successfully implemented internal control processes to improve profits. The data collected were from face-to-face interviews, analysis of company documents, and observation. The data analysis process included coding the information to develop patterns and themes. The themes identified in the study included operational strategies, methods to measure the effectiveness of internal controls, barriers to implementing internal controls, and ways internal controls improved profits. The implications for positive social change include the potential to provide construction business owners with effective strategies to implement internal control processes that may lead to increasing employment opportunities for individuals in local communities.
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Agbi, Clarence. "Scalable and Robust Designs of Model - Based Control Strategies for Energy - Efficient Buildings." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/333.
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In the wake of rising energy costs, there is a critical need for sustainable energy management of commercial and residential buildings. Buildings consume approximately 40% of total energy consumed in the US, and current methods to reduce this level of consumption include energy monitoring, smart sensing, and advanced integrated building control. However, the building industry has been slow to replace current PID and rule-based control strategies with more advanced strategies such as model-based building control. This is largely due to the additional cost of accurately modeling the dynamics of the building and the general uncertainty that model-based controllers can be reliably used in real conditions. The first half of this thesis addresses the challenge of constructing accurate grey-box building models for control using model identification. Current identification methods poorly estimate building model parameters because of the complexity of the building model structure, and fail to do so quickly because these methods are not scalable for large buildings. Therefore, we introduce the notion of parameter identifiability to determine those parameters in the building model that may not be accurately estimated and we use this information to strategically improve the identifiability of the building model. Finally, we present a decentralized identification scheme to reduce the computational effort and time needed to identify large buildings.
The second half of this thesis discusses the challenge of using uncertain building models to reliably control building temperature. Under real conditions, building models may not match the dynamics of the building, which directly causes increased building energy consumption and poor thermal comfort. To reduce the impact of model uncertainty on building control, we pose the model-based building control problem as a robust control problem using well-known H1 control methods. Furthermore, we introduce a tuning law to reduce the conservativeness of a robust building control strategy in the presence of high model uncertainty, both in a centralized and decentralized building control framework.
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Chow, Andy Ho Fai. "Adaptive traffic control system : a study of strategies, computational speed and effect of prediction error /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202002%20CHOW.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 126-129). Also available in electronic version. Access restricted to campus users.
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Akuh, Comfort G. "Small Retail Business Strategies to Detect and Prevent Employee Fraud." ScholarWorks, 2017. https://scholarworks.waldenu.edu/dissertations/4266.
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Small businesses have an important role to play in the U.S. economy. However, employee fraud can jeopardize the sustainability of small businesses. Grounded on Cressey's fraud triangle theory, the purpose of this multiple case study was to explore strategies used by selected managers and owners of small retail businesses to detect and prevent employee fraud. Ten participants from 5 small retail businesses participated in the study. Nine participated in a face-to-face semistructured interview, and 1 participated in a telephone interview. These participants included 5 owners and 5 managers of small retail businesses in the state of Michigan in the United States who have implemented strategies to detect and prevent employee fraud. Through a process of methodological triangulation, casual observations and documentary evidence supplemented data collected through semistructured interviews. Using thematic analysis by coding narrative segments, the research findings included themes of controls and communication, cash register accountability, segregation of duties, monitoring, and action against perpetrators. Managers and owners of small businesses may benefit from the findings of this study by gaining awareness of the need to detect and prevent employee fraud. The implications for positive social change may include the potential to increase appropriate controls over employee fraud, thus enabling owners of small retail business an opportunity to operate effectively and efficiently, which could increase employment opportunities. Increased employment opportunities could create a positive effect on other small retail businesses and allow local communities to prosper.
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Brahm, Laurence J. "Foreign exchange controls and strategies for the People's Republic of China." Thesis, Click to view the E-thesis via HKUTO, 1989. http://sunzi.lib.hku.hk/HKUTO/record/B38627772.
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Ortiz, Angel. "Strategies to Reduce Occupational Fraud in Small Restaurants." ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/5241.
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Occupational fraud is a growing business risk that is causing greater financial losses in small businesses than large businesses. Business owners lose approximately 5% of their revenues due to occupational fraud. The purpose of this multiple case study was to explore the strategies used by some business owners of small restaurants to reduce occupational fraud. The fraud triangle theory was the conceptual framework for this study. Three small restaurant owners from Puerto Rico participated in face-to-face, semistructured interviews to reveal their successful strategies to minimize fraud. The data collection process also included business documents and researcher observations that assisted in establishing methodological triangulation. Using Yin's 5-step process, data were coded and analyzed to identify emergent themes. The primary emergent themes obtained from data analysis revealed that owner monitoring, analytical procedures, and segregation of duties are effective strategies to minimize employee fraud. Participants revealed that the implementation of these strategies may reduce organizational losses associated to fraud. The findings of this study may contribute to social change by reducing fraud activities, business failures, unemployment level, and criminality rate while promoting trust between community members and their institutions.
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Serrao, Livia. "Fluvial and climatic controls on tropical agriculture and adaptation strategies in data-scarce contexts." Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/351060.
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Over the past decades, public concern about global environmental change has grown, following the progressive increase in both frequency and intensity of extreme events. Even though the problem is global, it has proved to have very different societal and environmental impacts at local level, further widening the gap between disadvantaged and advantaged communities, according to the degree of vulnerability of their social, economic and environmental systems. Among the various anthropogenic activities, the agricultural sector is particularly linked to global environmental change by a two-way relationship: on the one hand, intensive mono-cultures, together with intensive livestock production, compromise the environment and produce huge CO$_2$ emissions (one of the most important factors behind global warming); on the other hand, smallholder farming is one of the most endangered sectors by global environmental change, precisely because it depends heavily on the natural resources of the territory, including favourable weather and climate. Scientific research, supported by international institutions, has been working on this subject for several decades, analysing phenomena at global and local scale and providing medium and long-term forecasts capable of directing economic and political strategies. Such complex investigations become even more complex in contexts lacking reliable environmental data, where their low-quality and low representativeness weaken their reliability, compromising the reliability of the outcomes as well. This thesis seeks to respond to the increasing need of realistically addressing environmental phenomena that threaten rural communities and the environment on which they depend in low-income countries, by investigating two of the main environmental factors affecting tropical farming practices: river-floodplain dynamics and climate change. Despite data-related constraints, the environment of tropical rural areas still provides a unique opportunity to study several near-natural processes, such as the morphodynamics of mostly free-flowing rivers. Especially in foothill regions, unconfined or partially confined conditions of tropical rivers allow evaluating the natural dynamics of erodible river corridors, with erosion and accretion shaping their interactions with the adjacent floodplain and related human activities. At the same time, the complex terrain characterizing the river valleys at the foothills of high mountain chains also offers the opportunity to study interesting local meteorological processes, especially considering the interaction between synoptic-scale dynamics and local convective phenomena. In this context, local bottom-up initiatives and new and tailored-to-context strategies for adaptation to the ongoing environmental change are deepened following a multidisciplinary approach. This PhD research has been framed within an international cooperation project entitled “Sustainable Development and Fight against Climate Change in the Upper Huallaga basin (Peru)”, promoted by Mandacarù ONLUS, and funded by the Autonomous Province of Trento. The project aimed to enhance the resilience of the local farmers of the Upper Huallaga valley (Peru), facing the consequences of climate change and implementing new agricultural initiatives with a special attention to plantain and banana fields. Thanks to the support of the involved partners (Redesign by PROMER s.a.c., the Universidad Agraria Nacional de la Selva de Tingo Maria, in Peru, and the Edmund Mach Foundation of San Michele all’Adige, in Italy), the project provided the opportunity to carry out a consistent set of fieldwork activities over an 8-months period collecting hydro-morphological data, interviewing the local population, and installing two weather stations. The PhD thesis has been structured along two main parts, related to to the assessment of climate change effects on local agricultural practices, and the interplay between river-floodplain dynamics and floodplain agriculture. The part on the assessment of climate change includes two main research elements. First, a novel approach is used to evaluate climate change in data-scarce contexts: non-conventional data sources (population survey) are compared with conventional data sources (few local historical weather stations and global reanalysis data series – ERA5), to better account for the sub-daily time scale (local conventional sources only provide daily data), correlating weather changes perceived by farmers (more thunderstorms and longer drought periods) with climate variations deduced from quantitative data. Second, after having determined the most impacting meteorological variables on crops through the survey, a weather early-warning system has been developed to provide agro-meteorological forecasts to the \textit{bananeros} (banana farmers) of the Upper Huallaga valley. The system, based on the Weather Research and Forecasting (WRF) model, and enhanced with the assimilation of real-time observations from local meteorological stations installed during the project fieldwork, issues an alert when the predicted wind speed exceeds thresholds related to potential damage to the harvest, and spreads the warning via text messages. Such alerting system contains several novel features in relation to the socio-environmental context, allowing to discuss its potential for replication in analogous, vulnerable situations. The part on river-floodplain dynamics also includes two main research elements. First, a remote-sensing analysis is conducted at reach scale in two different reaches of the Huallaga River, quantifying geomorphological river trajectories and land use changes in the adjacent floodplain. The outcomes show that river morphology reacts differently depending on the agricultural systems (extensive or intensive) in the nearby floodplain, revealing a high geomorphological sensitivity of such a near-natural, highly dynamic river reach. Second, riverine agriculture within the erodible river corridor is analysed in association with riverine islands dynamics, at the geomorphic unit scale, evaluating the morphological evolution and agricultural suitability of two cultivated fluvial islands. The three main drivers of agricultural suitability within river erodible corridors, i.e. river disturbance, cultivation windows of opportunity, and soil suitability are quantified, allowing to generalize a process-based conceptual model of riverine islands as complex-adaptive-systems.
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Rockson, Albert. "Strategies for Preventing Financial Fraud in Church Organizations in Ghana." ScholarWorks, 2019. https://scholarworks.waldenu.edu/dissertations/7107.
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Financial fraud in church organizations is increasing rapidly, which can affect the reputation, donation appeal, future funding, and ability of church organizations to meet their planned organizational goals. The purpose of this multiple case study was to explore strategies for preventing financial fraud in church organizations. The conceptual framework for the study was Cressey’s fraud triangle theory. Twenty participants who utilize strategies for preventing financial fraud in their organizations were purposively selected from 5 church organizations in Ghana. Data were collected through semistructured interviews and analysis of organizational financial policy documents. Interview data were transcribed, coded, and analyzed with Saldaña’s coding guidelines. Data analysis followed recommendations from Yin, including examining the data, grouping data into categories, regrouping data in themes, interpreting the data, and producing empirically based findings that answered the central research question of the study. Three significant themes emerged from the data analysis: effective administration, good stewardship and accountability, and caliber of employees. Implementation of the findings may lead to positive social change by enhancing the donation appeal of church organizations, improving their finances, and enabling them to optimize their operations to benefit individuals, families, communities, and society.
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Valdes, Diaz Didier M. "Integrated information and traffic control strategies for congested urban freeway corridors /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Aljoaba, Sharif. "ACTIVE OPTIMAL CONTROL STRATEGIES FOR INCREASING THE EFFICIENCY OF PHOTOVOLTAIC CELLS." UKnowledge, 2013. http://uknowledge.uky.edu/ece_etds/18.
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Energy consumption has increased drastically during the last century. Currently, the worldwide energy consumption is about 17.4 TW and is predicted to reach 25 TW by 2035. Solar energy has emerged as one of the potential renewable energy sources. Since its first physical recognition in 1887 by Adams and Day till nowadays, research in solar energy is continuously developing. This has lead to many achievements and milestones that introduced it as one of the most reliable and sustainable energy sources. Recently, the International Energy Agency declared that solar energy is predicted to be one of the major electricity production energy sources by 2035.
Enhancing the efficiency and lifecycle of photovoltaic (PV) modules leads to significant cost reduction. Reducing the temperature of the PV module improves its efficiency and enhances its lifecycle. To better understand the PV module performance, it is important to study the interaction between the output power and the temperature. A model that is capable of predicting the PV module temperature and its effects on the output power considering the individual contribution of the solar spectrum wavelengths significantly advances the PV module designs toward higher efficiency.
In this work, a thermoelectrical model is developed to predict the effects of the solar spectrum wavelengths on the PV module performance. The model is characterized and validated under real meteorological conditions where experimental temperature and output power of the PV module measurements are shown to agree with the predicted results.
The model is used to validate the concept of active optical filtering. Since this model is wavelength-based, it is used to design an active optical filter for PV applications. Applying this filter to the PV module is expected to increase the output power of the module by filtering the spectrum wavelengths. The active filter performance is optimized, where different cutoff wavelengths are used to maximize the module output power. It is predicted that if the optimized active optical filter is applied to the PV module, the module efficiency is predicted to increase by about 1%. Different technologies are considered for physical implementation of the active optical filter.
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HAJIMIRZAALIAN, HAMIDREZA. "Robotic Biomedical Device for Recovering Cardiovascular Efficiency in Paraplegic Patients." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2540888.
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This thesis is studying on the Design and development of a biomechanical robotize IPC
device to accomplish a therapeutic methodology for recovery of cardio-circulatory
functions, which may be seriously impaired in paraplegic patients. This impairment is
caused by the reduction of venous return, due to the missing muscular contraction in
zones without innervations.
Intermittent Pneumatic Compression (IPC) is a well-known technique, which can be used
for several therapeutic treatments like sports recovery, lymphoedema drainage, and deep
vein thrombosis prevention. An IPC device produces a definite massaging action on the
limb by inflating and deflating a given number of bladders according to particular time
laws.
The designed IPC device in this thesis is proposed for the lower limb to recover the
venous return and preventing the Deep Vein Thrombosis (DVT) in the patients. The
experimental tests on the volunteer persons showed the significant improvements on the
important parameters of the cardiovascular, like the stroke volume (SV), the cardiac
output (CO), and the end diastolic volume of left ventricle (LVEDV).
To understand the dynamic behaviour of the IPC device and to optimize its performances,
the device is characterized based on the mechanical and physiological aspects and its
mathematical model is simulated in Simulink-Matlab. The validation of the mathematical
model is done by comparing results with the experimental one.
In addition, to apply the desired pressure pattern on the limb, two control strategies based
on the PID algorithm and regulating inflating time are implemented on the model. The
results of the controlled model, shows about 60% improving in performances of the
device as concerns the bladder pressure control. In this case the experimental test has been
done and it verified the control results of the simulation
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Axengren, Josefine, and Sandra Petersson. "Att lyckas med strategisk planering och strategisk kontroll – En fallstudie på två svenska företag." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-10443.
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En konkurrenskraftig strategi kan vara en avgörande faktor för ett företags framgång. En formell företagsstrategi ser till att både de som deltar i den strategiska planeringen och i genomförandet följer samma mål. Det riktas kritik mot hur företag använder sig av strategisk planering och den största utmaningen för företagen ligger i att implementera strategin i verksamheten. Ett problem som är kopplat till strategier är att organisationers sätt att skapa konkurrensfördelar förändras snabbt. Företagen måste på grund av detta skapa förutsättningar för en ständigt pågående strategisk dialog.Syftet är att undersöka hur små och medelstora företag (SMF) arbetar med den strategiska planeringen i verksamheten och hur de kontrollerar att de strategiska aktiviteterna verkar i linje med det långsiktiga målet. Syftet med studien är även att ta reda på vilka faktorer som bidrar till en lyckad strategisk planering och implementering hos SMF. För att besvara vårt syfte har en multipel fallstudie gjorts på två SMF i Sjuhäradsområdet. Personliga intervjuer har genomförts med personer från företagens ledningsgrupp och styrelse.SMF har gemensamma karaktärsdrag gentemot stora företag och följande områden har undersökts: omgivningsfaktorer, organisationsmiljö och ledningen. Storleken på företaget har en betydande roll när det kommer till hur stor påverkan omgivningen har på ett företag. SMF har mer begränsade resurser vilket bidrar till större osäkerhet i omgivningen och att hålla koll på bland annat andra konkurrenter. Organisationsstrukturen hos SMF kännetecknas av en platt struktur med få ledningsnivåer vilket bidrar till en hög flexibilitet och förmåga att anpassa sig till marknaden. De få ledningsnivåerna bidrar till att antalet mellanchefer är färre och kravet på Vd:ns ledningsexpertis ökar.The Closed-Loop Management System är en modell som föreslås användas vid strategisk planering hos företag. Modellen består av fem steg: utveckla strategin, översätta strategin, planera handlingar, kontrollera och lär samt testa och anpassa strategin. Modellen beskriver hur företag ska gå tillväga från att formulera och uttala strategin till att implementera och kommunicera den i verksamheten och har använts som underlag för att undersöka hur SMFs arbetar med strategisk planering och strategisk kontroll i praktiken. För att säkerställa att implementering av strategin blivit lyckad behöver företagen utföra strategisk kontroll. Ett sätt att utföra strategisk kontroll är genom att använda sig av integrerad prestationsmätning. Det innebär en balanserad styrning mellan finansiella och icke-finansiella mått där orsak- och verkansamband mellan de olika måtten kartläggs och har undersökts på företagen i studien.Slutsatser som kan dras av studien är att tre viktiga faktorer som bidrar till strategisk framgång i SMF är: inställningen hos de anställda, val av organisationsstruktur och tydlig kommunikation. För att genomföra den strategiska planeringen används ett metodiskt arbetssätt för att strukturera upp aktiviteter och delmål som finns för att uppnå det övergripande målet. Genom att bryta ned det övergripande målet i delmål och aktiviteter säkerställer företagen att de kortsiktiga handlingarna verkar i linje med den långsiktiga strategiska planen. Det är även viktigt för företagen att kontrollera och mäta dessa aktiviteter. Finansiella och icke-finansiella mått används för strategisk kontroll men studiens resultat visar att de finansiella måtten är dominerande.A competitive strategy is essential for a corporate’s success in their industry. The challenge is not only to design the strategy; it is to spread it throughout the organization. An integrated measurement system refers to support and control the activities and goals that leads to strategic success. Thus, earlier studies have shown that integrated measurement systems have contributed to improve large enterprises’ performances when applied in their businesses. However, this study refers to the gap of research on the use of integrated measurement systems and its impact on small and medium-sized enterprises (SME). This study focusses on two Swedish SMEs and research what characterize their qualities that contributes to strategic success. The study will also focus on how the SMEs apply strategic planning and strategic control in their business’s.The study was based on previous studies in the context of strategy. The interviews were conducted on two Swedish SMEs, and the respondents were people that are a part of each company’s management team that possess both knowledge and insight to the company’s strategic work.Our findings suggest that factors contributing to strategic success in SME’s are: the communication approach, the attitude of the employees and the organizational structure. The strategic planning in SME wasn’t based on a specific model to support the strategic planning. However, they use a similar methodical approach to implement the activities in the strategic planning process. Finally, the study also shows that SMEs use integrated measurement in terms of financial and non-financial measurements, where the financial measurements had a greater impact on the SME business’s.
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Gough, Brian. "Accidents and emergencies : an evaluation of the effectiveness of current management strategies and legal controls in mitigating accidents and injuries to fire service personnel in the performance of their duties, in operational and non-operational envir." Thesis, University of Ulster, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445053.
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Axelsson, Johanna, and Sarah Bernelind. "Elevator Control Strategies." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134900.
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The purpose of this essay is to investigate if it is eective to switch strategies for elevators during one day in an oce building. This essay describes some of the strategies in use today, followed by a comparison and analysis of two of the strategies described. We have also implemented optimizations to one of these strategies. From our test results we can conclude that our optimized strategy worked and produced better results on average waiting time and total traveling time than the two strategies we previously implemented and that it is not necessarily eective to completely change strategies but change parts of them depending on the trac ow.Syftet med denna rapport ar att undersoka om det ar eektivt att byta strategi for hissar i en kontorsbyggnad under en dags olika trakoden. Forst beskrivs nagra av de vanligaste strategierna, vilket foljs av en jamforelse och analys av tva av dessa. For att kunna jamfora dessa strategier har en implementation av ett program som simulerar en byggnad med hissar gjorts. I programmet anvands sedan dessa strategier for att ta fram testresultat. Den mest eektiva av dessa tva strategier har optimerats och jamforts ytterligare med de tidigare resultaten. Testresultaten visar att den optimerade strategin var den mest eektiva med avseende pa genomsnittsvantetiden och den totala genomsnittsrestiden, och att det inte ar nodvandigt att helt byta strategi under dagen, men att det lonar sig att optimera delar av den, beroende pa trakodet
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Ceder, Frederick, and Alexandra Nordin. "Elevator Control Strategies." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134902.
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This paper investigates the efficiency of known elevator control strategies by simulating these in an own made apartment simulator. Efficiency will be determined by the lowest product of the energy consumption (Watt/second), average waiting time, average transfer time and the maximum waiting time of a passenger, which is the output by the simulator. The apartment simulator will simulate the elevator behavior, according to a respective control strategy, and the passenger flow on each respective floor in a specific test scenario. In this test scenario, passengers always travel either to the ground floor or to their respective home floor to simulate an apartment complex on a workday. The outcome of the investigation was that a control strategy that would prioritize elevator orders, i.e. calls made from inside the elevator, remember calls and collect passengers that are on route was the most efficient, both in terms of low energy consumption and passenger satisfaction (low transit and waiting times).
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Johnson, Mackie. "Retail Inventory Control Strategies." ScholarWorks, 2016. https://scholarworks.waldenu.edu/dissertations/3171.
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Despite using computerized merchandise control systems in retail, the rate of stockouts has remained stagnant. The inability to satisfy customer needs has caused a loss of 4% in potential revenue and resulted in dissatisfied customers. The purpose of this qualitative multiple case study was to explore cost-effective inventory control strategies used by discount retail managers. The conceptual framework that grounded the study was chaos theory, which helped identify why some business leaders rely on forecasting techniques or other cost-effective strategies as an attempt to prevent stockouts. The target population was comprised of discount retail managers located throughout northeast Jacksonville, Florida. Purposeful sampling led to selecting 6 retail managers who successfully demonstrated cost-effective inventory control strategies for mitigating stockouts. Data were collected through face-to-face semistructured interviews, company websites, and company documents. Analysis included using nodes to identify similar words and axial-coding to categorize the nodes into themes. Transcript evaluation, member checking, and methodological triangulation strengthened the credibility of the findings. Five themes emerged: (a) internal stockout reduction strategies, (b) external stockout reduction strategies, (c) replenishment system strategies, (d) inventory optimization strategies, and (e) best practices for inventory control. This study may contribute to positive social change by improving inventory management, which may reduce demand fluctuations in the supply chain and reduce logistics costs in the transportation of freight thereby leading to improved customer satisfaction.
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Luu, Ngoc An. "Control and management strategies for a microgrid." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT075/document.
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Aujourd'hui et à l'avenir, l'augmentation des prix du carburant, la déréglementation et les contraintes de l'environnement donnent plus de possibilités pour l'utilisation des sources d'énergie renouvelables (SER) dans les réseaux électriques. Un concept de microgrid est nécessaire afin d'intégrer les sources d'énergie renouvelables dans le réseau électrique. Ce microgrid comprend un réseau de basse tension (BT) avec les ressources d'énergie distribuées (DER) ainsi que les moyens de stockage et des charges flexibles. L'intégration des énergies renouvelables dans un microgrid peut causer des enjeux et des impacts sur le fonctionnement du microgrid. C'est pourquoi dans cette thèse, un dimensionnement optimal et les stratégies de fonctionnement en sécurité, fiabilité et efficacité d'un microgrid comportant des productions photovoltaïques (PV), des systèmes de stockage d'énergie de la batterie (BESS) et / ou les diesels sont proposés. Tout d'abord, la technique d'optimisation itérative est utilisée pour trouver le dimensionnement optimal d'un microgrid. Deuxièmement, les stratégies de contrôle de tension et de fréquence pour un microgrid en mode îloté en utilisant les statismes sont étudiées. De plus, nous proposons les stratégies intelligentes de contrôle de tension et de la fréquence à l'aide de la logique floue. De cette manière, la fréquence est exprimée non seulement en fonction de la puissance active, mais aussi de l'état de charge de BESS et des régimes de fonctionnement de microgrid. Et enfin, une méthode pour optimiser la gestion de l'énergie dans l'exploitation d'un microgrid est proposée dans cette thèse. La programmation dynamique est utilisée pour trouver le minimum du coût du carburant compte tenu des émissions par la planification des ressources énergétiques distribuées (de DER) dans un microgrid en mode îloté ainsi que pour minimiser le coût d'énergie et les puissances d'échange avec le réseau en mode connecté. Les résultats de simulation obtenus montrent la précision et l'efficacité des solutions proposéesToday and in the future, the increase of fuel price, deregulation and environment constraints give more opportunities for the usage of the renewable energy sources (RES) in power systems. A microgrid concept is needed in order to integrate the renewable sources in the electrical grid. It comprises low voltage (LV) system with distributed energy resources (DERs) together with storage devices and flexible loads. The integration of RES into a microgrid can cause challenges and impacts on microgrid operation. Thus, in this thesis, an optimal sizing and security, reliability and economic efficiency operation strategies of a microgrid including photovoltaic productions (PV), battery energy storage systems (BESS) and/or diesels is proposed. Firstly, the iterative optimization technique is used to find the optimal sizing of a microgrid. Secondly, the voltage and frequency control strategies for an island microgrid by using droop control methods are studied. Furthermore, we propose intelligent voltage and frequency control strategies by using fuzzy logic. By this way, the frequency is expressed not only as the function of active power but also the state of charge of BESS and the operation states of microgrid. And finally, a method to optimize the energy management in operation of a microgrid is proposed in this thesis. Dynamic programming is used to find the minimum the cost of fuel considering the emissions by scheduling of distributed energy resources (DERs) in an island microgrid as well as to minimize the cash flows and the exchanged power with the main grid in a grid-connected mode. The simulation results obtained show the accuracy and efficiency of the proposed solutions
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MENGARELLI, ALESSANDRO. "Balance and Motor Control in Dynamic Tasks." Doctoral thesis, Università Politecnica delle Marche, 2017. http://hdl.handle.net/11566/245482.
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Nella prima parte dello studio si è descritto il mantenimento dell’equilibrio in seguito a perturbazioni indotte da stimoli esterni. La risposta posturale è stata analizzata dal punto di vista dinamico, cinematico ed elettromiografico, ottenendo una descrizione completa dei meccanismi adottati per contrastare la perdita di equilibrio. Vari parametri sono stati estratti dallo spostamento del centro di pressione e del centro di massa e sulla base dell’attività muscolare acquisita mediante elettromiografia di superficie, con lo scopo di ottenere indici che correlino con le diverse caratteristiche della perturbazione. Sulla base dei dati cinematici sono state descritte le strategie posturali adottate per contrastare la perturbazione indotta, allo scopo di quantificare se differenti condizioni perturbative facciano sorgere differenti risposte, che prevedono l’uso di differenti strategie articolari. Infine il controllo dell’equilibrio è stato descritto attraverso un modello a doppio pendolo inverso, attraverso tecniche che, sebbene ben note ed impiegate in altri ambiti, risultano poco usate per la descrizione della postura in condizioni dinamiche.
Nella seconda parte si è indagato il controllo della dinamica del cammino in termini di attività muscolare, acquisita su centinaia di passi consecutivi, permettendo un nuovo tipo di descrizione non basata solamente su parametri temporali ma anche sulla frequenza con cui ogni modalità di attivazione muscolare di presenta durante il cammino. I principali risultati includono la quantificazione dei pattern di co-contrazione dei flessori di caviglia e la loro ricorrenza durante il cammino. Si sono inoltre descritte le differenze legate al genere riguardanti l’attività dei principali muscoli dell’intero arto inferiore. Basandosi sui precedenti risultati si sono poi quantificate le differenze legate al genere nei pattern di co-contrazione degli antagonisti che regolano la meccanica dell’articolazione di caviglia durante il cammino.In the first part of this work a characterization of the upright stance recovery after balance perturbation administered through external stimuli was performed. Balance response has been analyzed in dynamics, kinematics and electromyographic terms, in order to obtain a complete description of which mechanisms are employed to withstand sudden stance perturbations. A series of parameters have been extracted from center of pressure and center of mass displacement and from electromyographic signals, acquired from lower limb and trunk muscles, in order to obtain a series of indexes which can correlate with the different characteristic of perturbations. From kinematic data, a description of the postural strategies adopted to withstand perturbations has been performed, in order to observe whether different perturbation conditions evoke different responses, employing different articular joints. Eventually, a first attempt to model perturbed upright stance through a double-link inverted pendulum is proposed, applying control systems seldom employed in describing this kind of dynamic motor task. In the second part, the motor control during the walking task was described in terms of muscular activity. Myoelectric signals were acquired in hundreds of consecutive strides, obtaining a new type of description, not only in terms of temporal parameters of muscles activity but also in terms of the occurrence frequency of each muscular activation modality during gait. The main outcomes include the description of co-contraction activity between ankle flexor muscles and the assessment of the recurrence of each co-activation pattern during walking. Furthermore, a description of the whole lower limb muscles behavior was performed, aimed to the quantification of gender-based differences in muscular recruitment during gait. Then, these two aspects were joined in assessing gender-related differences in co-contraction activity of muscles which control the ankle joint mechanics during walking.
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Kahriman, Edin, and Srdjan Jovanovic. "Alternative Strategies for Engine Control." Thesis, Linköpings universitet, Reglerteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119470.
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The existing powertrain control system in Volvo CE's vehicles consists of various types of physical quantities that are controlled. One of them is the engine speed. The purpose of this thesis is to investigate whether there are other control strategies suitable for engine speed control, than the existing one. Currently, the existing control system requires re-calibration of the control parameters if hardware in the vehicle is replaced. The current controller is a gain-scheduled PID controller with control parameters that varies over the operating range. The aim has been to develop several different adaptive control strategies. Adaptive control methods are expected to adapt to the changes of the system that a replacement of hardware can bring. The performance and robustness of the developed controllers have been compared with the existing controller. The approach has been to implement the control strategies in Matlab/Simulink and simulate the process with existing engine software provided by Volvo CE. The next step was to test and verify the controllers in a real machine. The focus in this thesis work has been on the adaptive control strategies MRAC (Model-Reference Adaptive Control) and L1 Adaptive Control. In the MRAC structure the desired performance is specified in terms of a reference model that the real system is supposed to follow. Each time an error is generated, by comparing actual and desired output, a suitable algorithm is used in order to obtain the control signal that can minimize the error. In addition, modeling errors and disturbances are estimated so that the controller can compensate for these. L1 Adaptive Control is an extension of the MRAC structure. The difference is that before the control signal is fed to the real system, it is low-pass filtered. This is done in order to prevent feeding high frequencies into the system. The results show that adaptive control has potential to be used in engine speed control. Reference following and disturbance rejection is well handled and simulations have furthermore shown that the developed controllers can deal with changes in the hardware. One of the developed L1-controllers was implemented in a real machine with promising results.Det existerande styrsystemet i Volvo CE:s maskiner har till uppgift att styra och reglera flera olika fysikaliska storheter. En av dessa storheter är motorvarvtalet. Syftet med detta examensarbete är att undersöka alternativa reglerstrategier som kan användas för att styra motorvarvtalet. Problemet idag är att det nuvarande styrsystemet kräver omkalibrering av regulatorparametrar när befintlig hårdvara i maskinen behöver ersättas på grund av föråldring eller slitage. Den nuvarande regulatorn är en parameterstyrd PID-regulator där regulatorparametrarna beror av aktuell arbetspunkt. Målet har varit att utveckla och prova flera olika adaptiva reglerstrategier. Dessa metoder förväntas kunna hantera förändringar och adaptera sig mot nya förhållanden och omständigheter som en hårdvaruförändring kan medföra. Prestanda och robusthet som de utvecklade regulatorerna erhåller har jämförts mot den existerande regulatorstrukturen. Tillvägagångssättet har varit att implementera reglerstrategierna i Matlab/Simulink samt simulera med tillhörande motormjukvara som Volvo CE tillhandahållit. I nästa fas skulle regulatorerna testas och verifieras i en riktig maskin. Fokuset har under detta examensarbete riktats mot de två adaptiva reglerstrategierna Model-Reference Adaptive Control (MRAC) och L1 Adaptive Control. MRAC-strukturen bygger på att specificera prestandan genom en referens-modell som det riktiga systemet skall följa. Varje gång en avvikelse uppstår så beräknas en lämplig styrsignal genom att beakta och försöka minimera skillnaden mellan det riktiga systemet och den önskade referens-modellen. Till detta modelleras och skattas störningar som regulatorn skall kompensera för. Tekniken inom L1 Adaptive Control är en utvidgning av MRAC. Önskat beteende specificeras även för denna regulatorstruktur men största skillnaden är att innan styrsignalen matas in till systemet så lågpassfiltreras den. Detta görs i förebyggande syfte för att inte släppa in onödigt höga frekvenser in i systemet. Resultaten visar att adaptiv reglering av motorvarvtalet har potential. Referensföljning och undertryckning av störningar hanteras väl och simuleringar har dessutom visat att de utvecklade regulatorerna kan hantera hårdvaruändringar. En av de utvecklade L1-regulatorerna implementerades i en riktig maskin och resultaten såg lovande ut.
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Ng, Kwai Choi Stanley. "Regulation strategies for process control." Thesis, University of Sunderland, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337287.
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Vychopeň, David. "Stanovení parametrů matematického modelu řídicí jednotky spalovacího motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231768.
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Master’s thesis is focused on creating a suitable methodology for determining the parameters of the electronic control unit of the engine. Discusses how the measurement of input data into the methodology, the basic description of its functions and display the resulting values. It includes evaluation of applicability of the methodologies and the real parameters when compared with the parameters established on the basis of established methodology.
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Goel, Anukul. "Control strategies for supercavitating vehicles." [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE0000537.
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Haviland, Jesse. "Control strategies for reactive manipulation." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/236551/1/Jesse%2BHaviland%2BThesis%282%29.pdf.
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For a robot to operate in the real world, which is dynamic, unstructured, and unknowable, it must be able to react and adapt to the ever-changing state of the robot, environment, and goal. This thesis develops novel reactive motion controllers, which, unlike prior approaches, can rapidly, robustly and safely operate in real-world environments. The thesis also provides extensive software and educational materials to encourage the adoption and ongoing development of this new reactive robot motion paradigm.
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Kasburg, Cristiane Regina. "Seleção e caracterização de isolados de fungos entomopatogênicos visando ao controle do ácaro vermelho Dermanyssus gallinae (Acari: Dermanyssidae)." Universidade Estadual do Oeste do Parana, 2016. http://tede.unioeste.br:8080/tede/handle/tede/711.
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Brazil is one of the largest producers of eggs, and this production is constantly growing, based on investment independent producers and the creation of cooperatives. Brazilian poultry facilities are mainly in wood with metal cages. There are few fully automated poultry, mainly by the high initial investment they require. The wooden structures, usually older, favor the appearance of some arthropod pests, as the poultry red mite Dermanyssus gallinae (De Geer, 1778) (Acari: Dermanyssidae). This mite is hematophagous and features gregarious and nocturnal behavior, spending the day hiding in cracks and crevices of the poultry houses, timber slots, dirt and debris accumulation of food and cobwebs. Among the damage caused by this mite infestation highlights the stress of birds, dermatitis and anemia, which can cause a decrease in production. Moreover, D. gallinae can also be transmitter the bacteria genus Salmonella, viruses of Newcastle disease and avian pox. Control strategies are mainly based on the use of chemical acaricides, which present risks to animals, poultry farmers and eggs consumers by residues in the eggs. Also, can select populations of resistant mites. Currently, the integrated management with use of less impactful strategies has been researched aiming their use at the field level. Among these strategies include the use of extracts and essential oils, inert powders (diatomaceous earth, silicas, talc), predators and entomopathogenic fungi. The entomopathogenic fungus has emerged as one of the most efficient techniques to control D. gallinae in laboratory conditions, but with a few field studies. The combination of these control strategies are also being studied aiming to find a method that is efficient and at the same time represents no risk to human and animal health.
O Brasil está entre os maiores produtores mundiais de ovos, sendo esta produção em constante crescimento, impulsionada principalmente por investimento de produtores independentes e da criação de cooperativas. As instalações aviárias brasileiras são principalmente em madeira com gaiolas metálicas. Há poucos aviários completamente automatizados, principalmente pelo alto investimento inicial que estes exigem. As estruturas em madeira, geralmente mais antigas, favorecem o aparecimento de alguns artrópodes-pragas, dentre os quais destaca-se o ácaro vermelho das galinhas Dermanyssus gallinae (De Geer, 1778) (Acari: Dermanyssidae). Este ácaro é hematófago e apresenta comportamento gregário e hábitos noturnos, passando o dia escondido em frestas e fendas dos aviários, ranhuras da madeira, restos de sujeira e acúmulo de comida e teias de aranha. Dentre os prejuízos causados pelas infestações deste ácaro, destacam-se o estresse das aves, a dermatite e a anemia, a qual pode ocasionar diminuição da produção. Além disso, D. gallinae também pode ser transmissor de bactérias do gênero Salmonella, vírus causadores da doença de Newcastle e da varíola aviária. As estratégias de controle são baseadas principalmente no uso de acaricidas químicos, os quais representam riscos aos animais, aos avicultores, aos consumidores pelos resíduos que podem deixar nos ovos, além de selecionar populações de ácaros resistentes. Atualmente, o manejo integrado com utilização de estratégias menos impactantes está sendo pesquisado, visando sua utilização no controle da praga. Dentre estas estratégias, destacam-se os extratos e óleos essenciais vegetais, pós inertes (terra de diatomáceas, sílicas, talcos), predadores e fungos entomopatogênicos. Os fungos entomopatogênicos têm se apresentado como uma das técnicas mais eficientes para controle de D. gallinae em condições de laboratório, porém com poucos estudos de campo. A combinação destas estratégias de controle também estão sendo pesquisadas visando encontrar um método que seja eficiente e ao mesmo tempo não represente riscos a saúde animal e humana.
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Laws, Christopher Neil. "Dynamic routing in queueing networks." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385435.
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Zázvorka, Tomáš. "Strategické řízení." Master's thesis, Vysoká škola ekonomická v Praze, 2012. http://www.nusl.cz/ntk/nusl-150214.
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The goal of this master's thesis is to perform a strategic analysis, to formulate a strategy on its basis and to propose the way of implementation and control of the strategy for the SAP division of the Pontech s.r.o. company and to contribute to successful implementation of strategic management system in this division and company. The thesis consists of two main parts. In the first, theroretically-metodological, part the terms and theories of strategic management and strategy are explained first and then the most common tools and methods of strategic analysis and further phases of strategic cycle i.e. formulation, implementation and control, which are used in the second, analytical, part, are mentioned. The analysis of macro and microenvironment, the analysis of internal resources and capabilities and the synthesis in the form of SWOT analysis is thus performed gradually, a strategy is formulated on that basis and after all the way of implementation and control of a strategy is performed using the principles of Balanced Scorecard system.
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Fariad, Mohamed. "Enjeux strategiques et contrôle interne : cas des établissements de crédit." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA111001.
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Le contrôle interne peut être défini comme étant l’ensemble des dispositifs, activités et actions mis en oeuvre au niveau de l’organisation pour influencer les comportements et atteindre des objectifs définis. Dans le domaine bancaire, il occupe une place centrale et se caractérise par une accumulation des exigences prudentielles. En même temps, le contrôle interne relève du dirigeant de l’établissement qui constitue sa pierre angulaire, mais qui pourrait avoir également des objectifs divergents avec le cadre ad hoc.Cette étude porte sur les interactions entre le dirigeant et le contrôle interne. Celles-ci semblent ambiguës du fait, d’une part, de la divergence d’objectifs entre les parties prenantes et, d’autre part, des limites du cadre du contrôle interne. Nous expliquons cette complexité par un contrôle interne à deux dimensions, à savoir une dimension managériale, comme levier permettant au dirigeant d’influencer les comportements des collaborateurs, et une dimension prudentielle, comme contrainte consistant à appliquer les normes prévues. Devant cette dualité, le dirigeant pourrait privilégier la dimension managériale par opportunisme, par un mauvais arbitrage ou une gestion inappropriée.Nonobstant leur importance, les normes prudentielles ne peuvent à elles seules pallier toutes les insuffisances et pourraient même constituer une contrainte pour le dirigeant qui pourrait être confronté à une divergence entre des objectifs individuels, collectifs et prudentiels. Face à l’accumulation des normes, la diversité des parties et les risques inhérents, le cadre du contrôle interne et le rôle du dirigeant gagneraient à être repensés et à évoluer vers un cadre bidimensionnel basé sur une gouvernance saine, l’éthique, des compétences et une répartition responsable des pouvoirsInternal control can be defined as being all the plans, activities and actions implemented in the organization to influence behaviours and reach defined objectives. In banking sector, it occupies a central place and is characterized by an accumulation of prudential requirements. At the same time, internal control is the responsibility of the manager of the establishment considered as its foundation, but who could also have divergent objectives with the ad hoc framework.This study concerns the interactions between the manager and the internal control. These seem complex mainly because, on the one hand, of the difference of objectives between the stakeholders and, the other hand, of limits of the internal control framework. This complexity can be explained by an internal control in two dimensions, namely a managerial dimension as lever allowing the manager to influence the employees behaviours, and a prudential dimension as a constraint consisting in applying the planned standards. Regarding this duality, the manager could privilege the managerial dimension by opportunism, a bad arbitration or by an inappropriate way of management.In spite of the importance of prudential standards, these cannot alone solve all the inadequacies and could even constitute a constraint for the manager who could be confronted to a difference between individual, collective and prudential objectives. In front of the accumulation of the standards, the diversity of the parties and the inherent risks, the framework of the internal control and the role of the manager would gain to be redesigned and to evolve towards a two-dimensional framework based on sound governance, ethics, skills and responsible distribution of powers
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Graciano, José Eduardo Alves. "Real time optimization in chemical process: evaluation of strategies, improvements and industrial application." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-12072016-094348/.
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The increasing economic competition drives the industry to implement tools that improve their processes efficiencies. The process automation is one of these tools, and the Real Time Optimization (RTO) is an automation methodology that considers economic aspects to update the process control in accordance with market prices and disturbances. Basically, RTO uses a steady-state phenomenological model to predict the process behavior, and then, optimizes an economic objective function subject to this model. Although largely implemented in industry, there is not a general agreement about the benefits of implementing RTO due to some limitations discussed in the present work: structural plant/model mismatch, identifiability issues and low frequency of set points update. Some alternative RTO approaches have been proposed in literature to handle the problem of structural plant/model mismatch. However, there is not a sensible comparison evaluating the scope and limitations of these RTO approaches under different aspects. For this reason, the classical two-step method is compared to more recently derivative-based methods (Modifier Adaptation, Integrated System Optimization and Parameter estimation, and Sufficient Conditions of Feasibility and Optimality) using a Monte Carlo methodology. The results of this comparison show that the classical RTO method is consistent, providing a model flexible enough to represent the process topology, a parameter estimation method appropriate to handle measurement noise characteristics and a method to improve the sample information quality. At each iteration, the RTO methodology updates some key parameter of the model, where it is possible to observe identifiability issues caused by lack of measurements and measurement noise, resulting in bad prediction ability. Therefore, four different parameter estimation approaches (Rotational Discrimination, Automatic Selection and Parameter estimation, Reparametrization via Differential Geometry and classical nonlinear Least Square) are evaluated with respect to their prediction accuracy, robustness and speed. The results show that the Rotational Discrimination method is the most suitable to be implemented in a RTO framework, since it requires less a priori information, it is simple to be implemented and avoid the overfitting caused by the Least Square method. The third RTO drawback discussed in the present thesis is the low frequency of set points update, this problem increases the period in which the process operates at suboptimum conditions. An alternative to handle this problem is proposed in this thesis, by integrating the classic RTO and Self-Optimizing control (SOC) using a new Model Predictive Control strategy. The new approach demonstrates that it is possible to reduce the problem of low frequency of set points updates, improving the economic performance. Finally, the practical aspects of the RTO implementation are carried out in an industrial case study, a Vapor Recompression Distillation (VRD) process located in Paulínea refinery from Petrobras. The conclusions of this study suggest that the model parameters are successfully estimated by the Rotational Discrimination method; the RTO is able to improve the process profit in about 3%, equivalent to 2 million dollars per year; and the integration of SOC and RTO may be an interesting control alternative for the VRD process.O aumento da concorrência motiva a indústria a implementar ferramentas que melhorem a eficiência de seus processos. A automação é uma dessas ferramentas, e o Real Time Optimization (RTO) ou Otimização em Tempo Real, é uma metodologia de automação que considera aspectos econômicos e restrições de processos e equipamentos para atualizar o controle do processo, de acordo com preços de mercado e distúrbios. Basicamente, o RTO usa um modelo fenomenológico em estado estacionário para predizer o comportamento do processo, em seguida, otimiza uma função objetivo econômica sujeita a esse modelo. Embora amplamente utilizado na indústria, não há ainda um consenso geral sobre os benefícios da implementação do RTO, devido a algumas limitações discutidas no presente trabalho: incompatibilidade estrutural entre planta e modelo, problemas de identificabilidade e baixa frequência de atualização dos set points. Algumas metodologias de RTO foram propostas na literatura para lidar com o problema da incompatibilidade entre planta e modelo. No entanto, não há uma comparação que avalie a abrangência e as limitações destas diversas abordagens de RTO, sob diferentes aspectos. Por esta razão, o método clássico de RTO é comparado com metodologias mais recentes, baseadas em derivadas (Modifier Adaptation, Integrated System Optimization and Parameter estimation, and Sufficient Conditions of Feasibility and Optimality), utilizando-se o método de Monte Carlo. Os resultados desta comparação mostram que o método clássico de RTO é coerente, desde que seja proporcionado um modelo suficientemente flexível para se representar a topologia do processo, um método de estimação de parâmetros apropriado para lidar com características de ruído de medição e um método para melhorar a qualidade da informação da amostra. Já os problemas de identificabilidade podem ser observados a cada iteração de RTO, quando o método atualiza alguns parâmetros-chave do modelo, o que é causado principalmente pela ausência de medidas e ruídos. Por esse motivo, quatro abordagens de estimação de parâmetros (Discriminação Rotacional, Seleção Automática e Estimação de Parâmetros, Reparametrização via Geometria Diferencial e o clássico Mínimos Quadrados não-lineares) são avaliados em relação à sua capacidade de predição, robustez e velocidade. Os resultados revelam que o método de Discriminação Rotacional é o mais adequado para ser implementado em um ciclo de RTO, já que requer menos informação a priori, é simples de ser implementado e evita o sobreajuste observado no método de Mínimos Quadrados. A terceira desvantagem associada ao RTO é a baixa frequência de atualização dos set points, o que aumenta o período em que o processo opera em condições subotimas. Uma alternativa para lidar com este problema é proposta no presente trabalho, integrando-se o RTO e o Self-Optimizing Control (SOC) através de um novo algoritmo de Model Predictive Control (MPC). Os resultados obtidos com a nova abordagem demonstram que é possível reduzir o problema da baixa frequência de atualização dos set points, melhorando o desempenho econômico do processo. Por fim, os aspectos práticos da implementação do RTO são discutidos em um estudo de caso industrial, que trata de um processo de destilação com bomba de calor, localizado na Refinaria de Paulínia (REPLAN - Petrobras). Os resultados deste estudo sugerem que os parâmetros do modelo são estimados com sucesso pelo método de Discriminação Rotacional; que o RTO é capaz de aumentar o lucro do processo em cerca de 3%, o equivalente a 2 milhões de dólares por ano; e que a integração entre SOC e RTO pode ser uma alternativa interessante para o controle deste processo de destilação.
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Munoz, Carpintero Diego Alejandro. "Strategies in robust and stochastic model predictive control." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:2f6bce71-f91f-4d5a-998f-295eff5b089a.
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The presence of uncertainty in model predictive control (MPC) has been accounted for using two types of approaches: robust MPC (RMPC) and stochastic MPC (SMPC). Ideal RMPC and SMPC formulations consider closed-loop optimal control problems whose exact solution, via dynamic programming, is intractable for most systems. Much effort then has been devoted to find good compromises between the degree of optimality and computational tractability. This thesis expands on this effort and presents robust and stochastic MPC strategies with reduced online computational requirements where the conservativeness incurred is made as small as conveniently possible. Two RMPC strategies are proposed for linear systems under additive uncertainty. They are based on a recently proposed approach which uses a triangular prediction structure and a non-linear control policy. One strategy considers a transference of part of the computation of the control policy to an offline stage. The other strategy considers a modification of the prediction structure so that it has a striped structure and the disturbance compensation extends throughout an infinite horizon. An RMPC strategy for linear systems with additive and multiplicative uncertainty is also presented. It considers polytopic dynamics that are designed so as to maximize the volume of an invariant ellipsoid, and are used in a dual-mode prediction scheme where constraint satisfaction is ensured by an approach based on a variation of Farkas' Lemma. Finally, two SMPC strategies for linear systems with additive uncertainty are presented, which use an affine-in-the-disturbances control policy with a striped structure. One strategy considers an offline sequential design of the gains of the control policy, while these are variables in the online optimization in the other. Control theoretic properties, such as recursive feasibility and stability, are studied for all the proposed strategies. Numerical comparisons show that the proposed algorithms can provide a convenient compromise in terms of computational demands and control authority.
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Ibrahim, Khan M. "Tuberculosis in Pakistan improving control strategies /." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=969899300.
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Kørte, Steffen Østensjø. "Guidance & Control Strategies for UUVs." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16228.
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Focus on safety and effectiveness in the oil and gas industry has increased the need for advanced control system for underwater vehicles. For remotely operated vehicles (ROVs) effectiveness when conducting deep sea operation is extremely critical both concerning safety and cost. For AUVs conducting survey missions, energy and collision avoidance are critical factors. A control system for ROV Minerva is being developed through the AUR-Lab at the Institute of Marine Technology at NTNU. Several guidance features have been investigated, with respect to different mission the ROV should be able to do. A guidance system has been developed, where basic functions such as a DP system with station keeping and trajectory tracking was the focus of the project thesis of the author. More advanced functionality with respect to path following has been developed, where focus have been set on different strategies to apply when the ROV is following a path. Simulations based on different strategies for following a lawnmower pattern have been simulated and evaluated with respect to time, energy and control objective. Full scale experiments with the ROV Minerva show that especially the forward speed versus arc radius is an important issue. The results show that the ROV is able to follow a path made out of straight lines and circular arcs, and particularly lawnmower patterns. For an underwater vehicle to be able to operate autonomously, stationary and dynamic obstacles have to be taken into account. A collision avoidance system based on local collision avoidance algorithms has been implemented, where focus has been on reactivity with respect to unmapped obstacles. The collision avoidance system has been through initial full scale tests with ROV Minerva, and the result are promising.
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Al-Mudhaffar, Azhar. "Impacts of Traffic Signal Control Strategies." Doctoral thesis, Stockholm : Division of transports and logistics, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4268.
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Zolotas, Argyrios C. "Advanced control strategies for tilting trains." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/4279.
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The use of tilting bodies on railway vehicles is becoming increasingly widespread: a number of well-established services using tilt technology already exist around the world, and will appear again in the UK over the next year or so. The motivation for tilting railway vehicles is that they give a cost-effective means of achieving a substantial reduction in journey time by increasing the vehicle speed during curves. Early tilt controller designs were based upon local vehicle measurements, however at that time this approach did not prove very successful. Nowadays most European manufacturers use the so called ‘precedence' control scheme, utilising measurements from precedent vehicles to achieve ‘precedence' information. However, achieving a satisfactory local tilt control strategy is still an important research target because of the system simplifications and more straightforward failure detection. The thesis describes a comprehensive study of tilt control, and its aim is to employ advanced control techniques - based upon practical sensors - with the particular objective of identifying effective strategies which can be applied to each vehicle independently, i.e. without using precedence control. The sensors employed for control design are in particular mounted on the vehicle passenger coach. Most of the work has been undertaken using Matlab, and this has included a proper assessment of the ride quality issues.
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Chacón, Vásquez Mercedes. "Strategies for wireless networked control systems." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28771.
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Networked Control Systems (NCS) and Wireless Networked Control Systems (WNCS) are control systems where controllers, sensors and final elements of control are connected to a mutual communication network. The inclusion of the network introduces delays and dropouts, which greatly influence the stability and robustness of the controller. While there is wealth in theoretical contributions to NCS, it is still imperative to study more applications and investigate the effects of networks in a real-time operation. There are also open problems that require further study of the impact of disturbances, constraints and strong interactions in complex NCS. This thesis is concerned with the design of control strategies for WNCS mainly focused on Model-Based Predictive Control (MBPC), Proportional Integral Derivative (PID) and decentralised schemes with the aim of creating control laws suitable for compensating time-varying delays and dropouts. These strategies rely on optimisation problems which incorporate robustness and performance restrictions to compute the optimum controller. The performance and robustness of the controllers are evaluated through extensive experiments in a network simulator. A new adaptive Internal Model Control (IMC) controller has been developed to adapt to the network requirements and compute the IMC model parameters online. A new robust PID for NCS under random delays has been created by solving a new constrained optimisation problem that included constraints of maximum sensitivity to guarantee robustness. A novel optimal immune PID is developed to improve the performance of NCS under time-varying delays and dropouts. Simulation results show that the controller offers greater flexibility and improves the performance and robustness with respect to the other methods studied. Four more controllers have been tested and extensive tests have indicated stability for a limited percentage of process model variations and dropouts. Predictive PID controllers, with similar properties to MBPC, are developed to compensate dropouts in WNCS. A quadratic programming problem optimises a new MBPC cost function to find the optimal PID gains. The approach successfully maximises the performance by changing the controller gains at every sampling time and allowing maximum variations of system parameters and dropouts. Also, a new constrained predictive PID controller is presented to deal with input saturation. Simulation results show the superiority of the design in comparison with the control schemes studied earlier. Furthermore, a decentralised wireless networked model predictive control design for complex industrial systems has been developed. Also, the method has been applied to wind farm control. The proposed decentralised control offers an effective and innovative solution to improve the performance of large industrial applications.
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Chen, Xin 1973. "Coordinating inventory control and pricing strategies." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29598.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2003.Includes bibliographical references (p. 127-130).
Traditional inventory models focus on effective replenishment strategies and typically assume that a commodity's price is exogenously determined. In recent years, however, a number of industries have used innovative pricing strategies to manage their inventory effectively. These developments call for models that integrate inventory control and pricing strategies. Such models are clearly important not only in the retail industry, where price-dependent demand plays an important role, but also in manufacturing environments in which production/distribution decisions can be complemented with pricing strategies to improve the firm's bottom line. To date, the literature has confined itself mainly to models with variable ordering costs but no fixed costs. Extending some of these models to include a fixed cost component is the main focus of this thesis. In this thesis, we start by analyzing a single product, periodic review joint inventory control and pricing model, and characterizing the structure of the optimal policy under various conditions. Specifically, for the finite horizon periodic review case, we show, by employing the classical k-convexity concept, that a simple policy, called (s, S, p), is optimal when the demand functions are additive. For the model with more general demand functions, we show that an (s, S, p) policy is not necessarily optimal. We introduce a new concept, the symmetric k-convex functions, and apply it to provide a characterization of the optimal policy. Surprisingly, in the infinite horizon periodic review case, the concept of symmetric k-convex functions allows us to show that a stationary (s, S, p) policy is optimal for both discounted and average profit models even for general demand functions.
(cont.) Our approach developed for the infinite horizon periodic review joint inventory control and pricing problem is then extended to a corresponding continuous review model. In this case, we prove that a stationary (s, S, p) policy is optimal under fairly general assumptions. Finally, the symmetric k-convexity concept developed in this thesis is employed to characterize the optimal policy for the stochastic cash balance problem.
by Xin Chen.
Ph.D.
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Abuzeid, Mustafa R. "Advanced braking control strategies for trains." Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/32027.
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The thesis describes modelling methods that are being developed to support the design and evaluation of intelligent railway braking control systems. A particular feature is that the models include higher order vehicle and train dynamics, the effects of which are expected to become important as the performance of braking systems improve. The thesis describes mathematical techniques for modelling braking systems starting with braking of a single wheelset on its own, then a single braked wheelset in a bogie, followed by a single braked wheelset in a complete vehicle and finally four wheelsets braked in a complete vehicle. The mathematical model for the braking system combines the non-linear creep laws governing the braking forces generated between wheel and rail with the suspension dynamics of a typical high speed railway vehicle.
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Round, Philip A. "Simulation of robot manipulator control strategies." Thesis, Aston University, 1988. http://publications.aston.ac.uk/11918/.
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The high capital cost of robots prohibit their economic application. One method of making their application more economic is to increase their operating speed. This can be done in a number of ways e.g. redesign of robot geometry, improving actuators and improving control system design. In this thesis the control system design is considered. It is identified in the literature review that two aspects in relation to robot control system design have not been addressed in any great detail by previous researchers. These are: how significant are the coupling terms in the dynamic equations of the robot and what is the effect of the coupling terms on the performance of a number of typical independent axis control schemes?. The work in this thesis addresses these two questions in detail. A program was designed to automatically calculate the path and trajectory and to calculate the significance of the coupling terms in an example application of a robot manipulator tracking a part on a moving conveyor. The inertial and velocity coupling terms have been shown to be of significance when the manipulator was considered to be directly driven. A simulation of the robot manipulator following the planned trajectory has been established in order to assess the performance of the independent axis control strategies. The inertial coupling was shown to reinforce the control torque at the corner points of the trajectory, where there was an abrupt demand in acceleration in each axis but of opposite sign. This reduced the tracking error however, this effect was not controllable. A second effect was due to the velocity coupling terms. At high trajectory speeds it was shown, by means of a root locus analysis, that the velocity coupling terms caused the system to become unstable.
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Devereux, David. "Control strategies for whole arm grasping." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/control-strategies-for-whole-arm-grasping(02ddb06c-3264-46e1-818a-8632b1bb05c4).html.
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Grasping is a useful ability that allows manipulators to restrain objects to a desired location or trajectory. Whole arm grasps are grasps that use the entire surface of the manipulator to apply contacts to an object. The problem of determining the shape of an object and planning a grasp for that object with a snake-like robot are considered in this work. Existing algorithms that attempt to allow robots to plan and perform whole arm grasps are lacking, they either use restrictive assumptions or have unrealistic demands in terms of required hardware. The work presented here allows even the most basic of robots to plan grasps on unknown objects whilst using a minimum of assumptions.The new developed Octograsp algorithm is a method of gaining information regarding the shape of the object to be grasped through tactile information alone. This contact information is processed using an inverse convex hull algorithm to build a model of the object's shape and position. The performance of the algorithms are examined using both simulations and experimental hardware, it is shown that accuracy errors as low as 3.1% can be obtained. The accuracy of the model depends upon factors such as the complexity of the object and the suitability of the robot. Manipulators consisting of a large number of small links with relaxed rotational constraints outperform other configurations. It is also shown that the accuracy can be improved by between 11% and 17% by contacting the object from multiple orientations, whilst also encircling from multiple positions can provide a very large improvement of between 56% to 86%. These methods allow even the coarse contact information provided by the experimental equipment to attain a model with an accuracy error of only 26%.A second novel algorithm is described that uses the information provided from the first algorithm to plan strong grasps over the desired object. The algorithm takes, on average, 25.1 seconds to plan the grasp. The mean strength of the planned grasps is 0.3816 using the wrench ball measure, this is firmly in the very good region. Several robotic configurations, as well as objects, are used to test the performance of the algorithm. The optimal parameters of the algorithm are investigated by using the results of 51030 different tests. It is again shown that robots that consist of a large number of small links and with high rotational ability perform the best.
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Auret, Erika Elizabeth. "Control strategies for citrus postharvest diseases." Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-06192006-084845.
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Wang, Baochao. "Intelligent control and power flow optimization of microgrid : energy management strategies." Thesis, Compiègne, 2013. http://www.theses.fr/2013COMP2122/document.
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La production intermittente et aléatoire des énergies renouvelables, sources photovoltaïques et éoliennes, est toujours un problème pour leur intégration massive dans le réseau public. L'une des solutions est de grouper des sources renouvelables, des sources traditionnelles, des dispositifs de stockage et des charges locales, et les traiter comme une seule unité dans le réseau public. Il s'agit du concept "micro-réseau". Un micro-réseau a des potentiels pour mieux répondre aux besoins de l'utilisateur final et du réseau public, et il facilite la mise en œuvre de futur smart grid, soit le réseau intelligent.Basé sur un micro-réseau représentatif en zone urbaine et intégré aux bâtiments, cette thèse propose une supervision multicouche, afin d'effectuer une étude systémique en mettant en exergue un verrou scientifique concernant l'implémentation d'une optimisation dans l'exploitation en temps réel.La supervision traite un ensemble d’opérations telles que : l'équilibré des puissances,l'optimisation des coûts énergétiques, utilisation de métadonnées, et échange d'informations avec le réseau intelligent et avec l'utilisateur final. Cette supervision a été validée par des tests expérimentaux. Malgré les incertitudes concernant les prévisions météorologiques, la faisabilité d'implémentation de l'optimisation dans l'exploitation réelle est vérifiée. La supervision proposée est en mesure de gérer efficacement les flux en assurant l'équilibre des puissances dans tous les cas. Néanmoins, la performance d'optimisation est liée aux précisions de prédiction. Ce problème peut être amélioré dans les travaux futurs par la mise à jour des résultats d'optimisation en temps réelThe intermittent and random production of renewable sources, such as photovoltaic and wind turbine, is always a problem for their large-scale integration in the utility grid. One of the solutions is to group renewable sources, traditional sources, storage and local consumption and treat it as a single unit in the utility grid. This is the concept of microgrid. A microgrid has the potentials of better responding both grid and end-user requirement, it facilitate the implementation of future smart grid. Based on a representative microgrid in urban area and integrated in buildings, this thesis proposes a multi-layer supervision, in order to realise a systemic study while particularly attempting to cover the research gap of implementing optimisation in realtimeoperation. The supervision handles together power balancing, energetic cost optimisation, metadata using, and information exchanges from both end-users and the smart grid. The supervision has been validated by experimental tests. The feasibility of implementing optimisation in real-time operation is validated even with uncertainties. The supervision is able to manage efficiently the power flow while maintaining power balancing in any case. Nevertheless, optimization effect relies on prediction precision. This problem can be improved in future works by updating optimization in real-time
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Löf, Marcus, and Elias Andersson. "Impact of Machine Learning on Elevator Control Strategies : A comparison of time efficiency for machine learning elevator control strategies and static elevator control strategies in an office building." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166399.
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Elevators are used in a large amount of buildings all over the world for fast and comfortable transportation. Today it is becoming increasingly important for people and products to be time efficient, and with technological development new solutions are created to answer this rising demand. To do this in an elevator context, elevator control strategies are implementedas optimal as possible. Machine learning is a relatively new concept, but it is already used in attempts to improve the performance of elevator control strategies. In this report the impact of machine learning on elevator control strategies is investigated in terms of average squared waiting times for the users. Machine learning algorithms can learn from both the current and past environments. The impacts of these two environments are also investigated. Three static elevator strategies and two versions of a machine learning elevator control strategy are implemented and run through a simulator. The results of the investigation show that machine learning has a significant impact on elevator control strategies and is proven to increase time efficiency with at least about 12.5%. Another conclusion drawn is that the current environment is most valuable in the user travel pattern down-peak, while information about previous days especially can improve the performance in the user travel pattern up-peak.
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Sethuraman, Shanthi. "Variable sampling interval control strategies for a process control problem." Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/40313.
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Skelton, Claude Eugene II. "Mixed Control Moment Gyro and Momentum Wheel Attitude Control Strategies." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9677.
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Attitude control laws that use control moment gyros (CMGs) and momentum wheels are derived with nonlinear techniques. The control laws command the CMGs to provide rapid angular acceleration and the momentum wheels to reject tracking and initial condition errors. Numerical simulations of derived control laws are compared. A trend analysis is performed to examine the benefits of the derived controllers. We describe the design of a CMG built using commercial off-the-shelf (COTS) equipment. A mixed attitude control strategy is implemented on the spacecraft simulator at Virginia Tech.Master of Science
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Sabattini, Lorenzo <1983>. "Nonlinear Control Strategies for Cooperative Control of Multi-Robot Systems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4465/1/sabattini_lorenzo_tesi.pdf.
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This thesis deals with distributed control strategies for cooperative control of multi-robot systems. Specifically, distributed coordination strategies are presented for groups of mobile robots.
The formation control problem is initially solved exploiting artificial potential fields. The purpose of the presented formation control algorithm is to drive a group of mobile robots to create a completely arbitrarily shaped formation. Robots are initially controlled to create a regular polygon formation. A bijective coordinate transformation is then exploited to extend the scope of this strategy, to obtain arbitrarily shaped formations. For this purpose, artificial potential fields are specifically designed, and robots are driven to follow their negative gradient.
Artificial potential fields are then subsequently exploited to solve the coordinated path tracking problem, thus making the robots autonomously spread along predefined paths, and move along them in a coordinated way.
Formation control problem is then solved exploiting a consensus based approach. Specifically, weighted graphs are used both to define the desired formation, and to implement collision avoidance. As expected for consensus based algorithms, this control strategy is experimentally shown to be robust to the presence of communication delays.
The global connectivity maintenance issue is then considered. Specifically, an estimation procedure is introduced to allow each agent to compute its own estimate of the algebraic connectivity of the communication graph, in a distributed manner. This estimate is then exploited to develop a gradient based control strategy that ensures that the communication graph remains connected, as the system evolves. The proposed control strategy is developed initially for single-integrator kinematic agents, and is then extended to Lagrangian dynamical systems.
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Sabattini, Lorenzo <1983>. "Nonlinear Control Strategies for Cooperative Control of Multi-Robot Systems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4465/.
Full textAbstract:
This thesis deals with distributed control strategies for cooperative control of multi-robot systems. Specifically, distributed coordination strategies are presented for groups of mobile robots.
The formation control problem is initially solved exploiting artificial potential fields. The purpose of the presented formation control algorithm is to drive a group of mobile robots to create a completely arbitrarily shaped formation. Robots are initially controlled to create a regular polygon formation. A bijective coordinate transformation is then exploited to extend the scope of this strategy, to obtain arbitrarily shaped formations. For this purpose, artificial potential fields are specifically designed, and robots are driven to follow their negative gradient.
Artificial potential fields are then subsequently exploited to solve the coordinated path tracking problem, thus making the robots autonomously spread along predefined paths, and move along them in a coordinated way.
Formation control problem is then solved exploiting a consensus based approach. Specifically, weighted graphs are used both to define the desired formation, and to implement collision avoidance. As expected for consensus based algorithms, this control strategy is experimentally shown to be robust to the presence of communication delays.
The global connectivity maintenance issue is then considered. Specifically, an estimation procedure is introduced to allow each agent to compute its own estimate of the algebraic connectivity of the communication graph, in a distributed manner. This estimate is then exploited to develop a gradient based control strategy that ensures that the communication graph remains connected, as the system evolves. The proposed control strategy is developed initially for single-integrator kinematic agents, and is then extended to Lagrangian dynamical systems.
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Effati, Shayan, and Donia Alipoor. "A Comparison of Traditional Elevator Control Strategies." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166689.
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The purpose of this paper is to investigate which of a specific set of elevator control strategies that is the most time efficient from the passenger’s point of view in a specific office building. The paper first goes through five different strategies and approaches, followed by results from a simulation of some of the strategies and their combinations. From the test results, it can be concluded that one strategy works best for all possible scenarios during a regular working day, both regarding the average waiting time for a passenger as well as the average travel time. The most optimal strategy implemented can be further optimized for more precise results, but it will not change the outcome of the comparison.
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Shabbir, Wassif. "Control strategies for series hybrid electric vehicles." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/39791.
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This thesis deals with the energy management problem of series hybrid electric vehicles (HEVs), where the objective is to maximize fuel economy for general driving. The work employs a high-fidelity model that has been refined to deliver appropriate level of dynamics (for the purposes of this research) at an acceptable computational burden. The model is then used to design, test and study established conventional control strategies, which then act as benchmarks and inspiration for proposed novel control strategies. A family of efficiency maximizing map strategies (EMMS) are developed based on a thorough and holistic analysis of the powertrain efficiencies. The real-time variants are found to deliver impressive fuel economy, and the global variant is found to outperform the conventional global benchmark. Two heuristic strategies are developed (exclusive operation strategy (XOS) and optimal primary source strategy (OPSS)) that are found to deliver significantly better fuel economy results, compared to conventional alternatives, and further desirable traits. This is found to be particularly related to the better use of modern start stop systems (SSSs) that has not been considered sufficiently in the past. A global heuristic strategy (GHS) is presented that successfully outperforms the conventional global benchmark without any particularly complex analysis. This exposes some of the limitations of optimization-based techniques that have been developed for simple vehicle models. Lastly, the sensitivity of the performance of the control strategies has been studied for variations in tuning accuracy, SSS efficiency, vehicle initial conditions, and general driving conditions. This allows a deeper insight into each control strategy, exposing strengths and limitations that have not been apparent from past work.
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Dockner, Engelbert J., and Long Ngo Van. "International Pollution Control: Cooperative Versus Noncooperative Strategies." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 1991. http://epub.wu.ac.at/6275/1/WP_2.pdf.
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Benameur, Kaouthar. "Control strategies for an active vision system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ44363.pdf.
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