Adaptive signal control systems react to traffic in real-time and adjust the signal timings to improve signal efficiency. SCOOT is the most widely implemented system. It comes from the UK with over 200 installations w...
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Adaptive signal control systems react to traffic in real-time and adjust the signal timings to improve signal efficiency. SCOOT is the most widely implemented system. It comes from the UK with over 200 installations worldwide including the US. Average delay reductions of 20 percent have been shown in urban networks that employ adaptive signal control systems. However, these benefits vary between cities. Until now, no commercially available adaptive signal control system could be modeled across a city-specific network prior to installation. the University of Utah has developed a simulation modeling connection between the Federal Highway's CORSIM model and the SCOOT adaptive control system. SCOOT runs on the VMS operating system, CORSIM on Windows NT. the two are connected via Ethernet with a dynamic link library interface that extracts the signal state and detector information from CORSIM and converts it to a format that SCOOT understands. SCOOT processes the information and sends it back across the Ethernet. In a completed loop, the optimized signal timing is then communicated from SCOOT to CORSIM, which implements the timing and updates the traffic simulation. this work offers traffic engineers the opportunity to evaluate the impact of SCOOT in a simulated environment prior to installation of the system. this paper reports the findings of the simulation of an actual urban network.
there have been numerous attempts to provide semantic recovery workflow support in order to maintain atomicity and consistency. However, they concentrate on compensation activities for individual tasks. this paper pro...
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One way for a systematic approach to fuzzy controller design is by applying genetic algorithms (GAs). GAs, however, are much more applicable to numerical-type optimization problems. A traditional fuzzy controller cont...
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ISBN:
(纸本)0780370783
One way for a systematic approach to fuzzy controller design is by applying genetic algorithms (GAs). GAs, however, are much more applicable to numerical-type optimization problems. A traditional fuzzy controller contains both linguistic-type rules and numeric-type reasoning. Hence, transforming a fuzzy controller design into a GA-applicable optimization problem becomes the first subject in the design approach. So, in this paper, we present an index function to represent the linguistic control rules in terms of numeric indices. In this way, a GA design approach becomes feasible. the index function has a tunable parameter which is adaptive to the controlled system and is novel to the fuzzy rule in a TSK (Tagaki-Sugeno-Kang) type fuzzy controller. Simulation results with a second-order damping system are presented to show the performance of the proposed fuzzy controller.
In this paper, we present a generic algorithm of solving a fuzzy constraint satisfaction problem (CSP) based on the notion of an adaptive level cut: the essence of our algorithm is to apply local propagation for solvi...
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In this paper, we present a generic algorithm of solving a fuzzy constraint satisfaction problem (CSP) based on the notion of an adaptive level cut: the essence of our algorithm is to apply local propagation for solving different level-cut CSPs. the task mainly involves repair operations to speed up the fuzzified local propagation by reusing as much of the computational effort from the previous level-cut as possible. Besides dealing with constraints in a discrete domain, the algorithm can also be extended to handle constraints in a continuous domain, based on the idea of interval-based reasoning.
this paper presents a robust fuzzy modeling based on L/sub 2/ gain criterion. the most important thing is that fuzzy modeling executes using LMI conditions. We derive an LMI condition to identify the parameters of a T...
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this paper presents a robust fuzzy modeling based on L/sub 2/ gain criterion. the most important thing is that fuzzy modeling executes using LMI conditions. We derive an LMI condition to identify the parameters of a Takagi-Sugeno fuzzy model (T-S fuzzy model). the LMI guarantees to minimize the summation of the upper bound of the identification error (SUE) between outputs of a real plant and those of a T-S fuzzy model. More importantly, we derive L/sub 2/ gain based fuzzy modeling conditions. It achieves robust parameter identification for the data contaminated by noise. An example shows the utility of the proposed iterative LMI approach to L/sub 2/ gain based fuzzy modeling.
the authors attempt a survey of current approaches carried out in the confluence of the two technologies: fuzzy set theory and object-oriented technology, that could provide a powerful tool for enhancing database mana...
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the authors attempt a survey of current approaches carried out in the confluence of the two technologies: fuzzy set theory and object-oriented technology, that could provide a powerful tool for enhancing database management systems, software modeling, and knowledge representation in AI systems. Possible types of fuzziness are discussed and key features related to different kinds of fuzzy software systems are also pinpointed out. In a nutshell, fuzzy theory, as a modeling mechanism, is especially useful in tackling real world applications whose complexity demands are growing intensively.
We propose a new design method for robust control configured systems with multiple design specifications. Since this design problem is formulated as the multiobjective minimax optimization problem, we use the genetic ...
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We propose a new design method for robust control configured systems with multiple design specifications. Since this design problem is formulated as the multiobjective minimax optimization problem, we use the genetic algorithm (GA) based technique to obtain the optimal solution. this design method is based on the input deviation, the minimax design approach and Pareto-partitioning GA. We apply this design method for designing a 4 wheeled steering car system. Some design examples are included to show the applicability and effectiveness of the proposed method.
Hybrid agent-based simulation is required to provide a mechanism for analyzing large-scale complex systems, such as the National Airspace system (NAS), more accurately and completely. the dynamic behavior of many larg...
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Hybrid agent-based simulation is required to provide a mechanism for analyzing large-scale complex systems, such as the National Airspace system (NAS), more accurately and completely. the dynamic behavior of many large-scale complex systems is, in general, hybrid in nature and thus can be best described by a combination of discrete-event and continuous-time models, and their interactions. Correspondingly, hybrid agent-based simulation capable of incorporating different types of models, such as continuous-time and discrete-event models, provides an accurate means of evaluating the reliability and performance of large, complex systems. However, in order to serve as a valuable design and analysis tool, a number of important issues must be addressed. this paper outlines issues in the development of hybrid agent-based simulation architectures capable of providing a scaleable mechanism for simulating the NAS. In particular, an object-oriented approach to hybrid agent-based simulation is described. In addition, methods of improving computational efficiency of updating the simulation are described and compared.
Predictive accuracy is the sum of two kinds of uncertainty-natural variability and modeling uncertainty. this paper addresses the quantification of predictive accuracy of complex simulation models from two perspective...
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Predictive accuracy is the sum of two kinds of uncertainty-natural variability and modeling uncertainty. this paper addresses the quantification of predictive accuracy of complex simulation models from two perspectives. First, it recognizes that there is a difference between variability and modeling uncertainty; the former can not be reduced with more test information, while the latter can. We suggest that variability is a natural form of uncertainty that can be quantified with probability theory, but that modeling uncertainty is a form that is better addressed by a theoretical foundation that is not based on random variables, but rather random intervals. We suggest possibility theory as the formalism to address modeling uncertainty. the paper discusses the two different methods, and illustrates the power of their integration to address predictive accuracy with a recent case study involving the crushing load of axially loaded metallic spheres.
the control of a nonlinear system where the characteristics are changing is difficult. In order to control the system, a study is needed to model during the execution and control. In this paper, a new evolutionary con...
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the control of a nonlinear system where the characteristics are changing is difficult. In order to control the system, a study is needed to model during the execution and control. In this paper, a new evolutionary control method is proposed that combines the evolutionary modeling by on-line GA and predictive fuzzy control. this control method is applied to the control of inverted pendulum where characteristics are modified actively to the external factor. the effectiveness of this control method has been confirmed.
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