Electromagnetic Transient (EMT) simulation tools are typically developed using conventional procedural programming languages. On the other hand, modern high-level and equation-based programming languages, such as Mode...
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Electromagnetic Transient (EMT) simulation tools are typically developed using conventional procedural programming languages. On the other hand, modern high-level and equation-based programming languages, such as Modelica, are currently available. Modelica allows formulating models that are easy to develop, maintain and understand by expressing what needs to be computed without stating how it should be computed. This paper presents a Modelica-based simulator for electromagnetic transients. It is demonstrated that this approach offers significant advantages for developing sophisticated models. Computational performance and accuracy are compared to a conventional EMT-type simulation tool.
The dairy industry is a unique branch of the food production sector, where various decisions have to be made concerning the type and quantity of the manufactured products and the layout of processing lines. The litera...
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The dairy industry is a unique branch of the food production sector, where various decisions have to be made concerning the type and quantity of the manufactured products and the layout of processing lines. The literature on the subject is relatively limited. Therefore, an attempt was made in this study to support decision making in the dairy industry. The article proposes a general methodology for modeling dairy production systems which are characterized by numerous interdependent and concurrent processing operations. The proposed method relies on the object-oriented modeling technique and graph theory, and it can be used to model the equipment and layout of production lines. The method enables multivariate simulations of the production process involving a specific batch of raw materials. The simulated variants differ in the configuration of the production line and/or the allocation of raw materials (semi-finished products) to different segments of the production line. The tested model was verified and validated, and the average relative error of estimation was 3.27% for butter production and 2.46% for buttermilk production. The proposed method could support decision-making in the process of selecting the production strategy, including the assortment and quantity of the manufactured products, and the configuration of production lines.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
Modernization of the economic function in the operating center cand result in improved reliability as well as economic savings for power system operators. Specifically, the development of accurate and computationally ...
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ISBN:
(纸本)9781665464413
Modernization of the economic function in the operating center cand result in improved reliability as well as economic savings for power system operators. Specifically, the development of accurate and computationally efficient methods for formulating and solving the alternative current optimal power flow (ACOPF) problem. In this paper, we utilize the Q-ACOPF formulation, which is an object-oriented quadratized formulation based on rigorous physically based mathematical modeling of the modern power system. The mathematical objects of power systems components are cast into a universal syntax that consists of linear and quadratic equations, the Quadratized Device Model (QDM) syntax. The optimization problem is constructed in an objected oriented fashion by operating solely on the component QDMs;the resulting problem consists of constraints that are at most quadratic with a quadratic objective function;hence why it is named Quadratic-OPF. We propose a convex solution sequential linear programming (CS-SLP) approach for the solution of the Q-OPF. We introduce a generalized convexification method and apply it to the Q-OPF. The two-step CS-SLP algorithm leverages commercial convex solvers, such as Gurobi, as well as LP solvers to efficiently obtain an optimal and feasible solution. We compare the results with those obtained from mature convex formulations QC and SOC (implemented in ***) on a five systems.
Just-in-time adaptive interventions (JITAIs) aim at health-promoting behavior change of individuals. Moving the development and evaluation of JITAIs beyond custom implementations for each specific use case will requir...
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ISBN:
(纸本)9781450394673
Just-in-time adaptive interventions (JITAIs) aim at health-promoting behavior change of individuals. Moving the development and evaluation of JITAIs beyond custom implementations for each specific use case will require integration-preserving customization, i.e., adaptation to different studies and participants without compromising integration for data analysis. For this purpose we develop a multi-level modeling (MLM) approach that builds on two-level structural conceptual models with composition and specialization extended by Cardelli power types yielding hierarchies of composite clabjects. We show the practical applicability of the approach through modeling of an example study on JITAIs for a digital health intervention, and demonstrate an RDF- and SHACL-based implementation.
This study presents the potential of using a natural ventilation system integrated with different combinations of enhancement techniques. The focus was on the perspective of using such configurations of passive ventil...
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This study presents the potential of using a natural ventilation system integrated with different combinations of enhancement techniques. The focus was on the perspective of using such configurations of passive ventilation systems (PVSs) in buildings located in different European cities. This work presents the results of obtaining the level of volumetric air flow rate for considering natural ventilation systems. Furthermore, the influences of local weather conditions (temperature, solar radiation, wind speed) were analyzed. Moreover, the year-round operation of all systems was presented. Also noted was the limitation of using PVSs based on the natural draft effect, additionally assisted by wind turbine ventilators in all European localizations. However, for the cities located in the northern part of Europe, it was confirmed that such a system can still meet minimum hygienic recommendations. It was also noted that a system additionally supported by a solar chimney is a much better solution. The best system was a PVS supported by a wind turbine ventilator and solar chimney integrated with PCM accumulation mass. The system should be additionally supported by waste heat from low-temperature sources. In the presented study, a high potential to reduce CO2 emission from building stock by the recommended system is additionally highlighted. However, there is still a need to analyze the proposed solutions by additional field tests and experimental investigations.
The modeling of physiological systems via mathematical equations reflects the calculation procedure more than the structure of the real system modeled, with the simulation environment SIMULINK (TM) being one of the be...
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The modeling of physiological systems via mathematical equations reflects the calculation procedure more than the structure of the real system modeled, with the simulation environment SIMULINK (TM) being one of the best suited to this strategy. Nevertheless, object-oriented modeling is spreading in current simulation environments through the use of the individual components of the model and its interconnections to define the underlying dynamic equations. In this paper we describe the use of the SIMSCAPE (TM) simulation environment in the object-oriented modeling of the closed loop cardiovascular system. The described approach represents a valuable tool in the teaching of physiology for graduate medical students. (c) 2013 Elsevier Ltd. All rights reserved.
Optimal power flow (OPF) has always played an important role in optimizing the operation of power systems, which are complex and highly nonlinear networks. The need for optimization is even more pressing in modern pow...
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Optimal power flow (OPF) has always played an important role in optimizing the operation of power systems, which are complex and highly nonlinear networks. The need for optimization is even more pressing in modern power grids with distributed energy resources (DERs, with or without storage) that introduce more flexibility, dynamics, and uncertainties to power grids. Most importantly, they add the time dimension to the optimization process: DERs generate the need to optimize systems in real time over a time horizon considering forecasts. This article proposes a multi-stage OPF formulation and solution method based on object-oriented device models with a rolling horizon incorporated for real-time optimizations to achieve optimal feedback control. The process also takes into account changing forecasts. The proposed approach is tested on a real distribution feeder and the results indicate that the method is very promising.
This Paper introduces a mission profile-based and simulation-driven framework for creating digital twins, by combining different modeling techniques into an integrated model of a complex electronic system used in auto...
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This Paper introduces a mission profile-based and simulation-driven framework for creating digital twins, by combining different modeling techniques into an integrated model of a complex electronic system used in automotive and railway applications. It envisages monitoring, diagnostics and prognostic of the condition, degradation or abnormalities in the electronic system's behaviour in the field. Furthermore, this work contributes towards the development of digital twins by adding black-box modules to the main simulation models, which can be achieved by employing the functional mock-up interface toolbox. The key features and functionalities of this approach for the simulation of digital twins will be also highlighted in this work. This approach is applied on a common example circuit, a full wave bridge rectifier, whose model is implemented and simulated in Modelica(1). Moreover, the functionality of the investigated circuit, as well as the degradation behaviour under variable external thermal as well as electrical loads, is demonstrated with the help of automated parametric studies performed within Python(+). Finally, the framework is verified using the functional test structure of the full wave diode bridge rectifier.
the graphical editor of electrical schemes for Rand Model Designer is presented. Rand Model Designer (RMD) is a universal visual tool for modeling and simulation of complex dynamical systems. The editor allows users t...
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ISBN:
(纸本)9781665404761
the graphical editor of electrical schemes for Rand Model Designer is presented. Rand Model Designer (RMD) is a universal visual tool for modeling and simulation of complex dynamical systems. The editor allows users to build models of electrical devises and carry out computer experiments using hidden calling of RMD. When graphical scheme of a device is completed, the editor automatically translates model description in RMD modeling language, checks, compiles it, and builds executable code in form of *.dll needed for carrying out computer experiments under RMD. The results of computer experiments are passed back to the editor for processing. The examples of using the editor in training are described.
Increased penetration of distributed energy resources (DERs) creates challenges in formulating the security constrained optimal power flow (SCOPF) problem as the number of models for these resources proliferate. Speci...
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ISBN:
(纸本)9781728155081
Increased penetration of distributed energy resources (DERs) creates challenges in formulating the security constrained optimal power flow (SCOPF) problem as the number of models for these resources proliferate. Specifically, the number of devices with different mathematical models is large and their integration into the SCOPF becomes tedious. Henceforth, a process that seamlessly models and integrates such new devices into the SCOPF problem is needed. We propose an object-oriented modeling approach that leads to the autonomous formation of the SCOPF problem. All device models in the system are cast into a universal syntax. We have also introduced a quadratization method which makes the models consisting of linear and quadratic equations, if nonlinear. We refer to this model as the State and Control Quadratized Device Model (SCQDM). The SCQDM includes a number of equations and a number of inequalities expressing the operating limits of the device. The SCOPF problem is then formed in a seamless manner by operating only on the SCQDM device objects. The SCOPF problem, formed this way, is also quadratic (i.e. consists of linear and quadratic equations), and of the same form and syntax as the SCQDM for an individual device. For this reason, we named it security constrained quadratic optimal power flow (SCQOPF). We solve the SCQOPF problem using a sequential linear programming (SLP) algorithm and compare the results with those obtained from the commercial solver Knitro on the IEEE 57 bus system.
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