No description available.

<p dir="ltr">This thesis presents a comprehensive dynamic modeling and model calibration framework and experimental validations for air-source heat pumps under cycling of frosting and reverse-cycle defrosting operations. </p>

<p>The objectives of this investigation were to experimentally and numerically assess the performance of a ball bearing supported turbocharger (TC). Turbochargers are mechanical devices used to improve the efficiency of modern engines. Using ball bearings improves the TC efficiency, and represents one of many evolving high-speed applications for ball bearings.</p> <p>The experimental objectives of this investigation were to design and develop a turbocharger test rig (TTR) to measure the shaft whirl of the rotating assembly and the axial and frictional loads experienced by the bearing cartridge. The TTR contains a ball bearing TC which was instrumented and operated under a variety of test conditions including rotational speeds up to 55,000 rpm. In order to measure the axial loads on the compressor and turbine sides, customized sensors were designed, fabricated and integrated into the TC housing. The anti-rotation (AR) pin, which normally prevents the bearing cartridge from rotating, was replaced with a custom-made sensor to measure frictional losses in the bearing cartridge.  These sensors were designed to minimally affect the operation of the TC. Proximity probes were initially installed on the compressor side and later on the turbine side to monitor shaft whirl using targets attached to the ends of the impellers. An assembly to record axial shaft motion with a proximity probe was also developed. Axial load and motion results indicated that the compressor side bears most of the axial load. As the backpressure or the speed of the TC increased the axial load also increased. Frictional measurements from the AR pin sensor demonstrated low power losses in the ball bearing cartridge. For certain shaft speed ranges, the data from the sensors illustrated periodic trends in response to subsynchronous whirl of the shaft.</p> <p>The numerical modeling objectives of this investigation were to characterize the dynamics of the ball bearing supported TC. In this TC, the compressor, turbine and shaft are supported by a bearing cartridge composed of back-to-back angular contact ball bearings. The cartridge is supported by squeeze film dampers (SFDs) and is prevented from rotation by the AR pin. To achieve the objectives, first an equivalent bearing model was developed to investigate the bearing dynamics and whirl of the TC rotating assembly. The TC bearing cartridge was modeled with a single deep groove ball bearing (DGBB) using the discrete element method. The SFD which supports the bearing was modeled with a bilinear spring and damper. A DGBB was used because it can support axial load in both directions. This model was then extended to include a flexible shaft represented by tetrahedral finite elements and supported by an ACBB cartridge. After this model was used to reproduce the whirl from the test rig, the bearing internal geometry and SFD properties were adjusted to determine their effect on shaft whirl. Wear and damage criteria were also developed to evaluate the simulation results. The best simulation result was obtained with a small clearance in the bearing and with a stiffer SFD. The clearance was necessary as the shaft and bearing deform at high speeds, preloading the bearing.</p> <p>The best simulation result was found to have reduced sliding and limited variation in contact force, which should lead to reduced friction and improved overall life. This study demonstrates the importance of taking the bearing system into account while designing a TC or other high speed mechanical system, as the bearing and SFD properties can have a significant impact on the system performance.</p>

В рамках данной работы изучены особенности использования систем поддержки взаимодействия с клиентами в работе колл-центра. Рассмотрены возможности архитектурного подхода в разработке модели информационно-сервисной поддержки. Осуществлен анализ тенденций использования CRM-систем в колл-центрах. Осуществлена оценка результативности использования информационно-сервисной поддержки работы колл-центра. Построена полная модель архитектуры ООО «Нейтив Фарм». На основе процессного подхода детально рассмотрены все фазы проекта по информатизации колл-центра. Разработана и реализована имитационная модель управления проектом разработки и внедрения проекта информационно-сервисной поддержки работы колл-центра на основе различных сценарием. Осуществлена оценка эффективности внедрения новой CRM-системы в деятельность колл-центра. / Within the framework of this work, the features of using customer interaction support systems in the work of a call center were studied. The possibilities of the architectural approach in the development of the model of information and service support are considered. An analysis of trends in the use of CRM-systems in call centers was carried out. An assessment of the effectiveness of the use of information and service support for the work of the call center was carried out. A complete model of the architecture of Native Pharm LLC was built. Based on the process approach, all phases of the call center informatization project are considered in detail. A simulation model for project management for the development and implementation of a call center information and service support project based on various scenarios has been developed and implemented. An assessment was made of the effectiveness of introducing a new CRM system into the activities of the call center.

В диссертации были изучены особенности применения цифровых сервисов по управлению научной деятельностью образовательной организации. Рассмотрены возможности архитектурного подхода в разработке сервиса по управлению научной деятельностью. Осуществлен анализ текущего состояния научной деятельности ГОУ ВПО «Донецкого национального университета». Построена полная модель архитектуры ГОУ ВПО «Донецкий национальный университет». Разработан цифровой сервис «Scientific and information portal» с использованием веб-ориентированной среды Oracle APEX. Разработана и реализована имитационная модель управления затратами при внедрении цифрового сервиса в управление научной деятельностью образовательной организации. / In the dissertation, the features of the use of digital services for the management of scientific activities of an educational organization were studied. The possibilities of an architectural approach in the development of a service for the management of scientific activities are considered. The analysis of the current state of scientific activity of the Donetsk National University is carried out. A complete model of the architecture of the State Educational Institution of Higher Education "Donetsk National University" has been built. The digital service "Scientific and information portal" has been developed using the Oracle APEX web-oriented environment. A simulation model of cost management has been developed and implemented when implementing a digital service in the management of scientific activities of an educational organization.

Была рассмотрена инновационная деятельность технологических процессов на угледобывающих предприятиях, построена полная модель архитектуры деятельности угледобывающего предприятия ГП «Шахта Комсомолец Донбасса», отражающая полный анализ деятельности предприятия с теоретической и практической точки зрения данных. Разработана система мониторинга, с помощью использования данной системы диспетчер сможет контролировать отслеживания всех процессов, связанные с образованием метана, которые будут происходить в шахте для своевременного обнаружения большого количества газа на участках и его устранения. Разработана имитационная модель управления угледобывающего предприятия ГП «Шахта Комсомолец Донбасса», позволяющая проводить анализ эффективности предприятия, предопределять результаты других показателей деятельности компании, отражать конечные результаты, а также осуществлять прогноз и планирование на основе различных сценариев. / The innovative activity of technological processes at coal-mining enterprises was considered, a complete model of the architecture of the activity of the coal-mining enterprise SE Komsomolets Donbassa Mine was built, reflecting a complete analysis of the enterprise's activities from a theoretical and practical data point of view. A monitoring system has been developed, using this system, the dispatcher will be able to monitor the tracking of all processes associated with the formation of methane that will occur in the mine for the timely detection of large amounts of gas in the areas and its elimination. A simulation model for the management of a coal mining enterprise SE "Komsomolets Donbassa Mine" has been developed, which makes it possible to analyze the effectiveness of the enterprise, predetermine the results of other indicators of the company's performance, reflect the final results, and also carry out forecasting and planning based on various scenarios.

<p dir="ltr">The U.S. food supply chain, particularly the beef industry, faces growing demands for transparency and traceability due to increased consumer awareness of environmental and social impacts. A lack of transparency and access to information, along with misinformation, pose challenges to brand trust and supply chain efficiency. Emerging information technologies like RFID and blockchain are being explored to enhance traceability and information transparency, forming the topic of this dissertation.</p><p dir="ltr">This study aims to understand how the growing demand for transparency in the U.S. beef industry could reshape its supply chain structure and dynamics. It comprehensively examines the potential of information technologies like blockchain to enhance traceability, reduce transaction costs and information asymmetry and shift the supply chain structure to vertical coordination.</p><p dir="ltr">To achieve these objectives, we employed System Dynamics (SD) to model the U.S beef supply chain from 2013 to 2022, leveraging on existing literature and statistical data. This methodology was selected because of its unique ability to capture dynamic complexities and feedback among variables, allowing us to assess market dynamics and evaluate potential changes in the beef supply chain under different information technology scenarios. The model was evaluated through a series of tests and demonstrated its efficacy in simulating and analyzing the dynamics of the beef supply chain.</p><p dir="ltr">We simulated a wide range of key policy initiatives on both supply and demand sides of the beef supply chain. Our findings reveal that blockchain adoption is influenced by various factors such as market dynamics, consumer preferences, and existing power imbalances within the supply chain. Scenario analyses suggest that larger firms may be less incentivized to adopt blockchain if the market isn't ready for transparency, due to high implementation costs. Conversely, smaller firms could benefit from reduced transaction costs. Also, our results show an increased willingness to pay for transparent beef boosts the market for smaller firms and raises beef prices. Regulatory intervention may be necessary to balance the power dynamic within the supply chain, especially considering the market power held by packers.</p><p dir="ltr">This study fills existing knowledge gaps and provides valuable insights for beef supply chain stakeholders. It organizes complex data into clear, communicable causal loop diagrams and then introduces a comprehensive U.S. beef supply stock-and-flow diagram, grounded in literature, data, and trends. Finally, by synthesizing complex data and providing practical tools for decision-making, this research offers a foundation for future studies and policy recommendations in the field of supply chain transparency.</p>

No description available.

В диссертации были изучены особенности использования методов машинного обучения в сфере страхования. Рассмотрены возможности архитектурного подхода в разработке модели машинного обучения. Осуществлен анализ тенденций цифровой трансформации сферы страхования. Осуществлена оценка результативности использования машинного обучения в страховании. Построена полная модель архитектуры ПАО СК «Росгосстрах». Разработана аналитическая модель машинного обучения в сфере тарификации страховой компании. На основе процессного подхода детально рассмотрены все фазы проекта по внедрению модели машинного обучения в деятельность страховой компании. Разработана и реализована имитационная модель управления проектом разработки и внедрения модели машинного обучения в деятельность страховой компании на основе различных сценарием. / The dissertation studied the features of using machine learning methods in the field of insurance. The possibilities of the architectural approach in the development of a machine learning model are considered. The analysis of trends in the digital transformation of the insurance industry has been carried out. The effectiveness of the use of machine learning in insurance has been evaluated. A complete model of the architecture of PJSC IC Rosgosstrakh was built. An analytical model of machine learning in the field of tariffing of an insurance company has been developed. Based on the process approach, all phases of the project to introduce a machine learning model into the activities of an insurance company are considered in detail. A simulation model for project management for the development and implementation of a machine learning model in the activities of an insurance company has been developed and implemented based on various scenarios.

A bilateral teleoperation system makes it possible for a human operator to interact with a remote environment and receive feedback from their actions. In this work, two different teleoperation architectures are studied, one well-established approach called position-force, and another approach called Model-Mediated Teleoperation (MMT). Position-force generates force feedback by measuring forces and sending them over the network, subject to network delay, while MMT generates nondelayed force feedback through a local environment model. The two architectures are compared in terms of transparency (quality of force feedback) and state consistency (equivalence of positions) under different network conditions. Up to 150 ms constant delay in Round Trip Time (RTT) is added. Both architectures are implemented as relatively simple versions of themselves. The case (teleoperation task) under consideration is pushing a cuboid object on a planar surface in a single direction. The MMT architecture is also studied in further detail, in terms of model complexity. Two versions of an MMT model are investigated, one simpler model that has a linear representation of energy loss and one less simple model that has a non-linear representation of energy loss. The purpose is to see what implications there are of increasing or decreasing model complexity. The results indicate that position-force has better performance in terms of both transparency and state consistency than both MMT models for all investigated network conditions. The simple version of MMT (linear model) performs better than the non-linear model, in terms of transparency and state consistency of cuboid positions, for all network conditions except the largest added delay. In terms of state consistency for the device positions, the non-linear model only performs better than the linear model with no added delay. / En distansstyrt system med tvåsidig kommunikation gör det möjligt för en mänsklig operatör att interragera med en avlägsen miljö och få återkoppling. I detta arbete studeras två olika arkitekturer för dessa typer av system. Ett väletablerat tillvägagångssätt som kallas position-force, och ett annat som kallas Model-Mediated Teleoperation (MMT). Position-force genererar kraftåterkoppling genom att mäta krafter och skicka dem över nätverket, utsatt för nätverksfördröjningar, medan MMT genererar en icke-fördröjd kraftåterkoppling från en lokalt modellerad miljö. De två arkitekturerna jämförs med avseende på ”transparency” (kvalitén på kraftåterkopplingen) och ”state consistency” (matchning av positioner) under olika nätverksförhållanden. De studerade förhållandena innefattar upp till 150 ms konstant fördröjning i tur och returtid. Båda arkitekturer implementeras som förhållandevis enkla versioner av sig själva. Det studerade fallet (operatörens uppgift) innefattar puttande på ett rätblock på en plan yta i en enkel riktning. MMT arkitekturen studeras även i vidare detalj med avseende på komplexitet hos den lokala modellen. Två versioner av MMT modellen undersöks, en enklare model som har en linjär representation av energiförlust, och en mer avancerad model som har en icke-linjär representation av energiförlust. Avsikten bakom detta är undersöka vilka implikationer som finns när komplexiteten hos modellen höjs eller sänks. Resultaten indikerar att position-force presterar bättre än MMT med avseende på både transparency och state consistency för alla undersökta nätverksfördröjningar. Den linjära MMT modellen presterar bättre än den icke-linjära modellen, med avseende på transparency och state consistency i rätblockspositioner, för alla nätverksförhållnaden utom den största pålagda fördröjningen. Vidare presterar den icke-linjära modellen bättre än den linjära modellen, med avseende på state consistency för styrande/styrd apparat, endast då ingen nätverksfördröjning läggs på.