Continuous System Simulation describes in detail how to build mathematical simulations of systems that change continuously over time. It covers:
- Numerical integration
- Simulation of stiff systems
...- Simulation of marginally stable systems
- Simulation of noisy systems
- Model validation techniques
- Simulation verification
- The inverse problem
- Dynamic nonlinear programming
- Simulation software
- Simulation hardware
Intended for advanced undergraduates in electrical, computer, mechanical, and civil engineering, it is a highly computer-oriented text, introducing numerical methods and algorithms along with the applications and conceptual tools. Homework problems, suggestions for research projects, and open-ended questions conclude each chapter.
En las últimas décadas la comunidad robótica ha adoptado cada vez más el uso de sensores GPS-RTK para estimar de forma precisa la localización de robots móviles en ambientes exteriores. En este ...trabajo se presenta la caracterización de un sistema GPS-RTK de bajo costo. A partir del montaje de las unidades base y móvil se adquirieron datos de posición corregidos en tiempo real por el mismo sistema RTK bajo diferentes disposiciones físicas, velocidades de actualización y condiciones ambientales presentándose posteriormente un estudio estadístico de los resultados obtenidos.
In this paper we introduce a general-purpose software tool for discrete event system specification (DEVS) modeling and simulation oriented to the simulation of hybrid systems. The environment, called ...PowerDEVS, allows atomic DEVS models to be defined in C++ language that can then be coupled graphically in hierarchical block diagrams to create more complex systems. The environment automatically translates the graphically coupled models into a C++ code which executes the simulation. A remarkable feature of PowerDEVS is the possibility to perform simulations under a real-time operating system (RTAI) synchronizing with a real-time clock, which permits the design and automatic implementation of synchronous and asynchronous digital controllers. Combined with its continuous system simulation library, PowerDEVS is also an efficient tool for real-time simulation of physical systems. Another feature is the interconnection between PowerDEVS and the numerical package Scilab. PowerDEVS simulations can make use of Scilab workspace variables and functions, and the results can be sent back to Scilab for further processing and data analysis. In addition to describing the main features of the software tool, the article also illustrates its use with some examples which show its simplicity and efficiency.
Efficient Matching in Large DAE Models Marzorati, Denise; Fernández, Joaquín; Kofman, Ernesto
ACM transactions on mathematical software,
06/2024
Journal Article
Recenzirano
Odprti dostop
This article presents a matching algorithm for bipartite graphs containing repetitive structures and represented by intension as Set-Based Graphs . Under certain conditions on the structure of the ...graphs, the computational cost of this novel algorithm is not affected by the cardinality of the sets of vertices and edges. The main application of the algorithm is that of matching large Equation-Based Models where, provided that most equations are defined using for loop statements that iterates over vectors of unknown variables, the computational cost becomes independent of the growth of the vectors involved. Besides introducing the algorithm, the article describes its implementation in a Modelica compiler and studies its performance over different test models.
► Characterisation of power response of a population of air conditioners. ► Implementation of demand side management on a group of air conditioners. ► Design of a controller for the power output of a ...group of air conditioners. ► Quantification of comfort impact of demand side management.
Large groups of electrical loads can be controlled as a single entity to reduce their aggregate power demand in the electricity network. This approach, known as load management (LM) or demand response, offers an alternative to the traditional paradigm in the electricity market, where matching supply and demand is achieved solely by regulating how much generation is dispatched. Thermostatically controlled loads (TCLs), such as air conditioners (ACs) and fridges, are particularly suitable for LM, which can be implemented using feedback control techniques to regulate their aggregate power. To achieve high performance, such feedback control techniques require an accurate mathematical model of the TCL aggregate dynamics. Although such models have been developed, they appear too complex to be effectively used in control design. In this paper we develop a mathematical model aimed at the design of a model-based feedback control strategy. The proposed model analytically characterises the aggregate power response of a population of ACs to a simultaneous step change in temperature set points. Based on this model, we then derive, and completely parametrise in terms of the ACs ensemble properties, a reduced-order mathematical model to design an internal-model controller that regulates aggregate power by broadcasting temperature set-point offset changes. The proposed controller achieves high LM performance provided the ACs are equipped with high resolution thermostats. With coarser resolution thermostats, which are typical in present commercial and residential ACs, performance deteriorates significantly. This limitation is overcome by subdividing the population into clusters of ACs that receive a coarse-grained, cluster-dependent control signal. The proposed clustering technique recovers the performance achieved with high resolution thermostats at the expense of some additional comfort penalty, which can be quantified using the controller output.
In this work we present an analytical expression that generalizes the definition of activity measure in continuous time signals. We define the activity of order n and show that it allows to estimate ...the number of sections of polinomials up to order n that are needed to represent that signal with certain accuracy. We apply this concept to obtain a lower bound for the number of steps performed by quantization–based integration algorithms in the simulation of ordinary differential equations. We performed a practical analysis over a first order example system, computing the activity of order n and comparing it with the number of steps required integration methods of different orders. We corroborated the theoretical predictions, which indicate that the activity measure can be used as a reference for assessing the suitability of different algorithms depending on how close they perform in comparison with the theoretical lower bound. Finally, a discussion is provided which indicates that further research is needed in order to test the results presented in this work in the context of stiff systems.
This paper describes the quantization-based integration methods and extends their use to the simulation of hybrid systems. Using the fact that these methods approximate ordinary differential ...equations (ODEs) and differential algebraic equations (DAEs) by discrete event systems, it is shown how hybrid systems can be approximated by pure discrete event simulation models (within the DEVS formalism framework). In this way, the treatment and detection of events representing discontinuities---which constitute an important problem for classic ODE solvers---is notably simplified. It can be also seen that the main advantages of quantization-based methods (error control, reduction of computational costs, possibilities of parallelization, sparsity exploitation, etc.) are still verified in the presence of discontinuities. Finally, some examples which illustrate the use and the advantages of the methodology in hybrid systems are discussed.
Celotno besedilo
Dostopno za:
CEKLJ, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This work presents retQSS, a novel methodology for efficient modeling and simulation of particle systems in reticulated meshed geometries. On the simulation side, retQSS profits from the ...discrete-event nature of Quantized State System (QSS) methods, which enable efficient particle tracking algorithms that are agnostic of the application domain. On the modeling side, retQSS relies on the standardized Modelica modeling language, yielding compact and elegant specifications of hybrid (continuous/discrete) dynamic systems. Combined together, these features offer a sound, general-purpose framework for modeling and simulation of particle systems. We show how the state-events that arise when particles interact with a reticulated mesh are seamlessly translated into easily tractable time-events. The latter can substantially improve simulation performance in scenarios where discontinuities dominate the computational demand. We showcase the flexibility of our approach by addressing four case studies arising from different application domains. Performance studies revealed that retQSS can perform similarly to, and even outperform, well-known domain-specific particle simulation toolkits while offering a clear and sound accuracy control interface.
•Generic and rigorous approach to particle simulation in reticulated 3D geometries.•Efficient particle tracking algorithms enabled by discrete-event based QSS methods.•Concise mathematical descriptions of particle models with the Modelica language.•Performance improvements when discontinuities dominate the computational demand.•Case studies: high-energy physics, molecular dynamics, plasma flow and bird flocking.
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