В диссертации рассмотрена оценка роли и значения имитационных моделей в построении и эксплуатации цифровых двойников. Проанализированы технологии создания и использования цифровых двойников и показано, что основой для их существования являются прототипы. Также рассматривается математическая модель, поддерживающая решение задачи стратегического управления с возможностью оценки рисков компании. Исследованы теоретические аспекты визуализации данных, классификации методов, функциональные возможности. / The thesis considers the assessment of the role and importance of simulation models in the construction and operation of digital twins. The technologies for creating and using digital twins are analyzed and it is shown that prototypes are the basis for their existence. A mathematical model is also considered that supports the solution of the strategic management problem with the possibility of assessing the company's risks. Theoretical aspects of data visualization, classification of methods, functionality have been studied.

Quang Ninh province, Vietnam has a rich wind power resources. This type of energy will be soon utilized for generating power to supply all industrial sites including mining corporations. Because of geological characteristics, wind power stations are located near the 6kV grid of mining areas, therefore it needs to make the analysis about the connection ability of wind power generators to the grids. The paper presents the connection model of a wind turbine and 6kV grids. Based on this model, the simulations of system’s possible operating mode are implemented. The conclusions about the suitable operating modes of wind turbine are pointed out to give the operators and grid managers a general observation for the possibility of connecting a wind turbine to 6kV grid / Tỉnh Quảng Ninh là một trong những địa phương giàu tiềm năng về năng lượng gió. Theo phân tích, loại năng lượng này sẽ sớm được đưa vào cung cấp điện năng cho các khu công nghiệp trong đó có các công ty than. Do đặc thù địa lý, các trạm phát phong năng được đặt khá gần các lưới điện 6kV của mỏ, vì thế cần tiến hành phân tích khả năng kết nối trực tiếp các máy phát điện gió với lưới điện này. Bài báo giới thiệu mô hình kết nối máy phát điện gió với lưới 6kV. Các mô phỏng về các chế độ vận hành có thể có của lưới cũng được thực hiện. Các kết luận về chế độ vận hành thích hợp của tua bin gió được đúc rút để giúp người vận hành, các nhà quản lý lưới điện có được cái nhìn tổng quan về khả năng kết nối tua bin gió với lưới điện 6kV.

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Road freight transport is changing, with an uncertain future and climate change calling for adaptation. Batteries as the power source are one solution for sustainable transport, yet these are affected by degrading effects, eventually making the batteries unusable. However, previous studies have shown that stationary second-life applications are possible for the used batteries. Another possibility is to reuse batteries in trucks with lower load requirements, thus extending their useful life, which also could aid in coping with the large number of batteries that battery electric vehicles will require. Nevertheless, few scholars have focused on this, and the literature is scarce. How battery usage affects truck performance in different life cycles must then be answered. Additionally, a proper business model must be adopted since the ownership of batteries and responsibility for the degrading becomes less clear with several users. Hence, investigating how more circular business models for batteries perform compared to linear business models is enticing. However, the uncertain future makes several possible future scenarios equally likely to happen, leading to future planning struggles. This work dives into the problem by developing a simulation model that uses a future scenario framework to simulate the effect of battery usage and different business models in the future. This work has several valuable contributions. First, it shows that using batteries in several lifecycles has benefits. Second, more circular business models for batteries can be more beneficial than linear business models, depending on the future values and payment methods. Above all, this work also has implications on a greater level, showing the potential value of using simulation methods in product and business model development processes. Using such models can develop products and business models to be sustainable, robust against futu reuncertainties, and perform the best on a module, product, and company level. In short, this study has shown the value of combining future scenarios with technical and business model aspects to simulate the future and gain insights for development. / Vägtransport är under förändring, där en osäker framtid och miljöförändringar kräver anpassning. Batterier som energikälla är en lösning för hållbara transporter, dock är dessa påverkade av degraderingseffekter, som till slut gör batterierna oanvändbara. Tidigare studier har visar på att återanvändning i stationära applikationer är möjligt för använda batterier. En annan möjlighet är att återanvända batterier i lastbilar med lägre belastningskrav, och därmed förlänga dess användbara liv, vilket också kan hjälpa att hantera det stora behovet av batterier som batteri-elektriska fordon kommer kräva. Dock är litteraturen om detta otillräcklig. Därmed måste batterianvändingens påverkan på lastbilsprestanda i olika livscykler av batteriet undersökas. Utöver det måste också en lämplig affärsmodell användas eftersom ägandeskapet av batterier och ansvaret för degradingseffekter blir mindre tydlig med flera användare. Därför är det intressant hur cirkulära affärsmodeller för batterier presterar jämfört med linjära affärsmodeller. En osäker framtid med många möjliga framtida scenarier gör planering för framtiden svårt. Detta arbete hanterar problemet genom att skapa en simuleringsmodell som använda ett ramverk för framtida scenarier för att simulera effekten av batterianvändning och affärsmodeller i framtiden. Detta arbete bidrar med flera viktiga insikter. För det första, visas att användning av batterier i flera livscykler har fördelar jämfört med bara en livscykel. För det andra, visas att mer cirkulära affärsmodeller för batterier kan vara förmånligt jämfört med linjära affärsmodeller, beroende på framtida värderingar och betalningsstrukturer. Framförallt visar detta arbete implikationer på en högre nivå, genom att visa potentialen av att använda simuleringsmodeller i utvecklingsprocesser för produkt och affärsmodeller. Genom att använda denna typ av model kan produkter och affärsmodeller utvecklas till att vara hållbara, robusta mot framtida osäkerheter, och prestera bäst på en modul-, produkt-, och företagsnivå. Sammanfattat visar denna studie på värdet av kombinera framtida scenarier med tekniska- och affärsmodellsaspekter för att simulera framtiden och få insikter för utveckling.

The development of Digital Twin Technology, with a focus on addressing environmental concerns, has elevated the priority of Industry 4.0-based solutions. The study aimed to design a simulation model to optimize the electricity consumption of the electric bus fleet at Arlanda Airport as a subproject of the main Digital Twin project. The study found that there was no current model designed to simulate electricity consumption by formal methods, Z notation.  The research is guided by four primary objectives find power management strategies for e-buses, identify critical parameters affecting their energy consumption, create a Z Notation simulation model, and assess this model. Through a thorough review of the literature and methodical application, power management strategies were defined, and significant energy consumption parameters were identified. The model's usefulness in modelling and optimizing electricity usage was demonstrated by its careful construction using Z Notation and evaluation with Spivey's Fuzz Checker. The paper demonstrates the use of Design Science Research in creating a digital twin-based simulation, which has important implications for transportation systems as well as theoretical advances in simulation methodologies. Throughout the developed Z notations, it provide a proper insight into operational efficiency and sustainability in energy consumption.  The study also emphasizes the drawbacks of using Z Notation, such as its steep learning curve and limited community assistance. To improve the accuracy of electricity consumption forecasts, future research should use predictive analytics and fine-tune the model granularity. The thesis demonstrates how design science can be applied for preparing specification of services but not only in software development. This work lays the groundwork for more extensive applications in digital twin technologies and energy optimization, in addition to contributing to our understanding of e-bus power management at Arlanda Airport.

Global supply chains are facing significant challenges due to the changes in supply and demand. This will increase the need for flexible and sustainable management. Lean production is a widely adopted methodology that companies use to enhance efficiency, reduce costs, and shorten lead times by optimizing internal logistics systems. Mapping and visualization tools are essential for understanding and improving transportation processes within companies while minimizing waste.The objective of this study is to provide companies with clearer insights into theirinternal transport flows through lean production and facility planning. By mappingtheir structures, companies can enhance their decision-making processes. This studyaims to achieve an understanding of the need for internal transport flow mappingthrough various methods and analyses. It also seeks to increase knowledge ofdifferent tools within lean production and facility planning to visualize the currentstate of internal transportation between buildings.The study was conducted through interviews, observations, and GPS measurements to map the transport processes at Xylem. Data were analyzed both qualitatively and quantitatively to ensure high scientific quality. The results and current state analysiswere based on these methods, leading to reliable conclusions about Xylem's current state.By using various lean tools and facility planning techniques, it is possible to create a mapping that provides companies with insights into their current situation. Several improvement suggestions for the current structure and work methods can potentially create faster flows with fewer misunderstandings in the work process. The study concludes that flow mapping functions as a tool to create a simplified simulation model. By interviewing and observing drivers and using diagrams to show utilization and time distribution, it is possible to analyze and examine internal transport planning and identify unnecessary waste.

Effektiviteten av automatiserade reningsprocesser inom avloppsreningsverk beror ytterst på kvaliteten av de mätdata som fås från installerade instrument. Givarfel påverkar verkens styrning och är ofta anledningen till att olika reglerstrategier fallerar. Idag saknas standardiserade riktlinjer för hur instrumenteringsarbetet på svenska reningsverk bör organiseras vilket ger begränsade förutsättningar för reningsverken att resurseffektivt nå sina utsläppskrav. Mycket forskning har gjorts på att optimera olika reglerstrategier men instrumentens roll i verkens effektivitet har inte givits samma uppmärksamhet. Syftet med detta examensarbete har varit att undersöka hur instrumentering på reningsverk kan organiseras och struktureras för att säkerställa mätdata av god kvalitet och att undersöka effekter av givarfel på reningsprocessen. Inom arbetet genomfördes en litteraturstudie där instrumentering på reningsverk under-söktes. Effekter av givarfel på reningsprocessen undersöktes genom att simulera en fördenitrifikationsprocess i Benchmark Simulation Model no. 2 där bias och drift implementerades i olika givare. Simuleringar visade att positiva bias (0,10–0,50 mg/l) i en ammoniumgivare inom en kaskadreglering bidrar till att öka luftförbrukningen med cirka 4–25 %. Vidare resulterade alla typer av fel i DO-givare i den sista aeroba bassängen i en markant större påverkan på reningsprocessen än samma fel i DO-givare i någon av de tidigare aeroba bassängerna. Om den sista aeroba bassängen är designad för att hålla lägre syrehalter är DO-givaren i den bassängen den viktigaste DO-givaren att underhålla. Positiva bias (200–1 000 mg/l) i TSS-givare som används för att styra uttaget av överskottsslam bidrog till kraftiga ökningar av mängden ammonium med cirka 29–464 % i utgående vatten. Negativ drift i DO-givare visade att stora besparingar i luftningsenergi, cirka 4 %, var möjliga genom ett mer frekvent underhåll av DO-givarna. Huruvida ett instrument lider av ett positivt eller negativt givarfel, bias eller drift, kommer att påverka hur mycket och i vilken mån reningsprocessen påverkas. Studien av givarfel visade att effekten av ett positivt eller ett negativt fel varierade och att effekten på reningsprocessen inte var linjär. Effekten av givarfel på reningsprocessen kommer i slutändan att bero på den implementerade reglerstrategin, inställningar i regulatorerna och på den styrda processen. / The effectiveness of automated treatment processes within wastewater treatment plants ultimately depend on the quality of the measurement data that is given from the installed sensors. Sensor faults affect the control of the treatment plants and are often the reason different control strategies fail. Today there is a lack of standardized guidelines for how to organize and work with online sensors at Swedish wastewater treatment plants which limits the opportunities for treatment plants to reach their effluent criteria in a resource efficient manner. Much research has been done on ways to optimize control strategies but the role of sensors in the efficiency of the treatment plants has not been given the same level of attention. The purpose of this thesis has been to examine how instrumentation at wastewater treatment plants can be organized and structured to ensure good quality measurement data and to examine how sensor faults affect the treatment process. Within the thesis a literature study was conducted where instrumentation at wastewater treatment plants was examined. The effects of sensor faults were examined by simulating a pre-denitrification process in Benchmark Simulation Model no. 2 where off-sets (biases) and drift where added to measurements from different implemented sensors. The simulations showed that positive off-sets (0.10–0.50 mg/l) in an ammonium sensor within a cascaded feedback-loop adds to the energy consumption used for aeration by roughly 4-25%. It could further be shown that all types of faults in a DO sensor in the last aerated basin had significantly larger effect on the treatment process than the same fault in any of the other DO sensors in the preceding basins. If the last aerated basin is designed to have low DO concentrations the DO sensor in that basin is the most important DO sensor to maintain. Positive off-sets (200–1 000 mg TSS/l) in suspended solids sensors used for control of waste activated sludge flow contributed to large increases of ammonia, by 29-464%, in effluent waters. Negative drift in DO sensors showed that significant savings in aeration energy, roughly 4%, was possible to achieve with more frequent maintenance. Whether a sensor is affected by a positive or a negative fault, be it off-set or drift, will affect how much and in what way the treatment process will be affected. The study of sensor faults showed that the effect of a positive or a negative fault varied and that the effect on the treatment process was not linear. The effect of a sensor fault on the treatment process will ultimately depend on the implemented control strategy, settings in the controllers and on the controlled process.

Volvo GTO is one of the strongest brands in the truck industry, with a long and proud history of world-leading innovations. The factory in Skövde produces diesel engines of various sizes to Volvo GTO. The project has been carried out on the processing part of grovdel crankshaft. Where the objective was to construct a simulation model that reflects flows 0, 1 and 2 on the crankshaft grovdel order to produce the best driving style for the size of the batches and sequences, focusing on PIA, between the stock and conversion-up times. A theoretical study intervention gave knowledge to the methodology to ensure that the data is collected and processed correctly. The data were collected in an Excel document, which was integrated with the simulation model for an overview and adjustments would be possible. The simulation program, Siemens Plant Simulation 12 used in the construction of the complex model of the three flows, which where verified and validated against the real flows. Optimization on the simulation model was made with a high and a low demand for crankshafts. Several objects were taken into consideration as: minimal waiting processing Findel, minimal setup time and minimal total-PIA from a truly viable perspective. The optimization showed a possible production planning in order to best be able to run such large batches as possible with reduced readjustment time and for delays of production in processing rawflows to not occur in the refined flow. For maximum capacity in the company there are two different optimal solutions one solution focused on reducing setup time and the second solution to minimize the number of additional production hours per week. Discrete simulation of production flows are being used to support production planning and simulation model is created for the continued use of the Volvo GTO, either in simulation group or future researches and theses in collaboration with the University of Skövde. The project objectives were achieved with good results and resulted as a standing basis for future planning of batches and sequences of processing crankshaft Volvo GTO.

New emission legislation regarding air pollution control, as instructed by the Department of Environmental Affairs (DEA) to Eskom Generation Power Stations, implies a particulate emission limit of 100 mg/Nm3 for all existing power stations by 2015 and 50 mg/Nm3 for all new and existing power stations by the year 2020. Some of Eskom’s power stations which are equipped with Electrostatic Precipitators (ESP’s) were not designed for this stringent legislation. It is also experienced that ESP’s and coal quality in Eskom have deteriorated over time, resulting in the performance of the ESP’s not meeting the legislative requirements. Eskom is in the process of introducing various ESP enhancement projects to improve performance and aligning the operating philosophy to comply with the more stringent particulate emission legislation. An ESP efficiency test was conducted at Lethabo Power Station to determine the current state of the plant and performance. The results of the test were compared with the original design base specifications to determine the relevant deficiencies which contribute to high emissions and poor ESP performance. It was aimed to develop an ESP simulation model and validate the outputs with the test data. This study endeavours to demonstrate the greater impact on ESP performance when the ESP is operated outside the design specification. It is further aimed to demonstrate that a solution to the problem of high emissions is not only contributed by the variables within the ESP itself. This study is a coal to stack evaluation considering the ESP variables and the upstream conditions of the ESP that form part of the entire process. The intention of this study is to demonstrate the importance of operating an ESP at the designed parameters and highlight the significance of proper maintenance. It was learned that before any ESP enhancement technology can be implemented, the ESP and upstream conditions must be in accordance with design specifications. The implementation of an ESP enhancement technology will have no merit or justification on a unit that is being operated outside of its design specifications. The results obtained from the ESP simulation model correlated well with the ESP efficiency test data. The expectation of the model to assist operators and engineers to operate ESP’s according to the designer’s specifications was conceded. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014