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The paper presents recent technological advancements that have been made by Siemens PLM in its simulation tools for multi-body analyses and multi-physics simulation in order to run physics-based high fidelity models in real-time. The motivation is enable reuse of simulation models developed during the engineering phase during the validation phase with hardware or humans in the loop. To demonstrate...
In this paper, we deal with the problem of determining when and where a bus should short-turn on a single bi-directional line in real-time. We formulate a decision rule for when to short-turn among candidate short-turning locations that is based on the objective of minimizing total generalized passenger travel cost including waiting times and forced transfer. Computational results and analysis are...
Real-time Calculus (RTC) is a non-stochastic queuing theory to the worst-case performance analysis of distributed real-time systems. Workload as well as resources are modelled as piece-wise linear, pseudo-periodic curves and the system under investigation is modelled as a sequence of algebraic operations over these curves. The memory footprint of computed curves increases exponentially with the sequence...
The purpose of a real-time simulation is to provide a closed loop system required for validating the control firmware or application. Detailed plant model with tolerable accuracy and achieving required real-time model execution time are conflicting requirements for a given embedded target hardware. In design of control methods for Pulse Width Modulation (PWM) inverters analytical models are important...
Network calculus (also known as real-time calculus) and event stream theory are two theories designed to compute upper bounds on response time for real-time systems. Both generalise the common periodic request arrival to any kind of workload using cumulative functions. In network calculus, a data flow is modelled by its cumulative curve, A(t), representing the amount of data sent by the flow up to...
Simulation is an extremely valuable tool for designing, operating and understanding complex systems in Power systems and Power Electronics. Broadly simulation can be of two types, Off-line and Real-time Simulation. Off-line simulation uses a digital computer and real time simulation uses a dedicated high speed digital processing hardware. Real time simulation allows analysis of a physical system in...
Cyber-physical systems (CPS) consist of physical entities that obey dynamical laws and interact with software components. A typical CPS implementation includes a discrete controller, where software periodically samples physical state and produces actuation commands according to a real-time schedule. Such a hybrid system can be modeled formally as a hybrid automaton. However, reachability tools to...
This paper presents a comparison of several open-loop methods for hysteresis compensation on a lab-made micro-/nanopositioning device. The classical Preisach model with the inverse multiplicative structure, and the Classical/Modified Prandtl-Ishlinskii models with model inversion, are considered. The classical Preisach method though suited for asymmetric hysteresis, does not have an analytic inverse...
This paper is about designing and constructing real-time systems, using mechanisms that support self-organization. Objects make a popular and convenient paradigm for keeping persistent data encapsulated with the operations that act on it, but they tend to omit what is arguably the most important aspect of real-time systems, which is time. There are other mechanisms that do model time, but few of them...
Computer simulation of realistic crowd behavior has been the focus of active research for more than two decades now. In crowd simulation, there is usually a trade-off between performance and realistic crowd behavior. In this paper, we propose a model, based on potential fields, that enables the introduction of many behaviors in crowd simulations, while keeping good performance. The model uses multiple...
Cyber-Physical Systems (CPS) is an integration of the computation process and physical processes, which can be modeled as a hybrid system. From the modeling perspective of CPS systems, the paper analyzes the limitations of traditional hybrid models, and proposes the extended hybrid automata model. The extended model is capable of representing hierarchy, concurrency and network delay. Finally, by modeling...
From the perspective of physical system feedback control, the cyber or computer system's role has been to sample and compute control inputs sufficiently fast to maintain acceptable reference command tracking and disturbance rejection in the physical system. This strategy has been successful given the relatively low computational overhead for most control laws compared to computational resource availability...
Software validation is an attempt to ensure the product fulfills its specific intended purpose. Software validation is very important since software is widely embedded in devices, and these devices are ubiquitous in our daily life nowadays. As software is getting more complex, the software validation process is getting more complicated and time consuming. The study of software validation is therefore...
The interaction between pantograph and catenary is the present problematic of current collection in electrical railways. Current collection enhancement is a key requirement for train speed-up in railway industry. Several models have been proposed in this sense to investigate the dynamic response of pantograph-overhead contact line. This paper presents a review of different pantograph and catenary...
We present an approach to connect the Real-Time Calculus (RTC) method to the synchronous data-flow language Lustre, and its associated tool-chain, allowing the use of techniques like SMT-solving and abstract interpretation which were not previously available for use with RTC. The approach is supported by a tool called ac2lus. It allows to model the system to be analyzed as general Lustre programs...
Real-time systems usually involve a subtle interaction of a number of distributed components and have a high degree of parallelism, which makes their performance analysis quite complex. Thus, traditional techniques, such as simulation, fail to produce reasonable results. Formal methods pose an interesting solution but they usually lack the capabilities to reason about quantitative time and probabilistic...
Real-time systems used in media processing and transmission produce bursty workloads with highly variable execution and transmission times. To avoid the drawbacks of using the worst-case approach with these workloads, this paper uses a variation of the usual real-time task model where the WCET is replaced by a discrete statistical distribution. Using this approach, tasks are characterized by their...
Schedulability analysis based the worst-case response time is an important research issue in real-time systems. Due to the restriction that the traditional schedulability analysis for fault-tolerant real-time systems only considered that the deadline of each task must be no larger than its period, this paper extends the computation model that the deadline of each task can be longer than its period...
Model based analysis has the potential to facilitate maintenance of complex real-time systems, as it allows for impact analysis with respect to the systems' temporal behavior. Model based analysis of temporal behavior of a legacy real-time system has also the potential to support migration toward component based system. However, since most software systems today have been developed in a traditional,...
Round-Robin scheduling is the most popular time triggered scheduling policy, and has been widely used in communication networks for the last decades. It is an efficient scheduling technique for integration of unrelated system parts, but the worst-case timing depends on the system properties in a very complex way. The existing works on response time analysis of task scheduled under Round-Robin determine...
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