Use Of Heuristic Information Research Articles

Optimization of the Membership Functions for a Fuzzy Controller Using an Improved Genetic Algorithms

Fuzzy control is a practical alternative for a variety of challenging control applications since it provides a convenient method for constructing nonlinear controllers via the use of heuristic information; this is done through the application of the techniques that use human judgment and experience rather than precise mathematical models. However, obtaining an optimal set of fuzzy membership functions (i.e. transferring the operator experience) is not an easy task. Different ways are suggested to deal with this problem. In this paper, we will use a powerful tool based on genetic algorithm to design a fuzzy logic controller that is used as a supervisor of PID controller that is the fuzzy controller is used to tune the PID controller for a feed water of a steam generation system. The simulation results show that the proposed technique is very useful to get an effective control action for the system.

A comparison of heuristic best-first algorithms for bicriterion shortest path problems

A variety of algorithms have been proposed to solve the bicriterion shortest path problem. This article analyzes and compares the performance of three best-first (label-setting) algorithms that accept heuristic information to improve efficiency. These are NAMOA ∗, MOA ∗, and Tung & Chew’s algorithm (TC). A set of experiments explores the impact of heuristic information in search efficiency, and the relative performance of the algorithms. The analysis reveals that NAMOA ∗ is the best option for difficult problems. Its time performance can benefit considerably from heuristic information, though not in all cases. The performance of TC is similar but somewhat worse. However, the time performance of MOA ∗ is found to degrade considerably with the use of heuristic information in most cases. Explanations are provided for these phenomena.

A Numerical structural approach to surge detection and isolation in compression systems using fuzzy logic controller

Fuzzy control is a practical alternative for a variety of challenging control applications since it provides a convenient method for constructing nonlinear controllers via the use of heuristic information. This approach provides a formal methodology for representing, manipulating, and implementing a human’s heuristic knowledge about how to modeled and to control a system. This paper focuses on the application of fuzzy control approach to the surge phenomena in centrifugal compression system. Fuzzy controller is designed to consist of an active surge control and phase control without any explicit system models, but driven in the human thinking mechanism. This fuzzy control methodology suggested in this work reproduced well the main characteristics of the turbo compressor dynamic model developed by Moore and Gretzer and give place to a more precise and easy to handle representation. Application and simulation results are performed to demonstrate the effectiveness of this controller. Studies show that, the proposed controller provides good tracking control performance for the compression system at different operating conditions and moreover improves the dynamic performances of the system.

Fuzzy logic control of a robot manipulator in 3D based on visual servoing

AbstractVisual servoing is a useful approach for robot control. It is specially attractive when the control objective can be stated directly in image coordinates. Fuzzy control is a practical alternative for a variety of challenging control applications since it provides a convenient method for constructing nonlinear controllers via the use of heuristic information, which for instance may come from an operator who has acted as a “human-in-the-loop” controller for a process. Fuzzy control strategy offers an alternative approach for many conventional systems, which has certain advantages over the other techniques. In this work, we proposed a control algorithm for a robot manipulator, which combines fuzzy logic with 3D visual servoing. For implementation only image coordinates are required. Simulation results show the good performance of the complete system.

Multiobjective constructive heuristics for the 1/3 variant of the time and space assembly line balancing problem: ACO and random greedy search

In this work we present two new multiobjective proposals based on ant colony optimisation and random greedy search algorithms to solve a more realistic extension of a classical industrial problem: time and space assembly line balancing. Some variants of these algorithms have been compared in order to find out the impact of different design configurations and the use of heuristic information. Good performance is shown after applying every algorithm to 10 well-known problem instances in comparison to NSGA-II. In addition, those algorithms which have provided the best results have been employed to tackle a real-world problem at the Nissan plant, located in Spain.

An enhanced exact procedure for the absolute robust shortest path problem

AbstractThe aim of this paper is to investigate the use of heuristic information to efficiently solve to optimality the robust shortest path problem. Starting from the exact algorithm proposed by Murty and Her, we describe how this algorithm can be enhanced by using heuristic rules and evaluation functions to guide the search. The efficiency of the proposed enhanced approach is tested over a range of random generated instances. Our computational results indicate that the use of heuristic criteria is able to speed up considerably the search and that the enhanced exact solution method outperforms the state‐of‐the‐art algorithm proposed by Murty and Her in most of the instances.

Parallel Logic Programming for Problem Solving

We present a new model for parallel evaluation of logic programs. This model can exploit the main sources of parallelism that the language of logic expresses: Independent {\sc and} parallelism and {\sc or} parallelism, together with a secondary source emerging as a consequence of the Independent {\sc and} Parallelism: the producer/consumer parallelism. The efficiency is derived from the use of ordered structures for managing the information generated throughout the search process. The model is suitable for evaluating programs with a high degree of non-determinism because it never generates two processes for solving the same subgoal and hence it can exploit the same real parallelism generating a lower number of processes than other models. As an application example, we consider the Job Shop Scheduling problem. We report experimental results showing that logic programs can be designed that exhibit parallelism, and that the use of heuristic information translates into speedup in obtaining answers.

Reaction path synthesis strategies

AbstractA system is offered for the mathematical representation of the functional and structural features of organic molecules and their reactions. Two basic synthesis strategies, an antithetic method anda synthetic method, are defined and compared. The use of heuristic information in guiding synthesis is evaluated. A synthetic method which uses dynamic programming is presented and applied to the synthesis of bihelical DNA. Possible extensions to other classes of compounds are presented.

<u>Correction</u> to "A Formal Basis for the Heuristic Determination of Minimum Cost Paths"

Our paper on the use of heuristic information in graph searching defined a path-finding algorithm, A*, and proved that it had two important properties. In the notation of the paper, we proved that if the heuristic function ñ (n) is a lower bound on the true minimal cost from node n to a goal node, then A* is <u>admissible;</u> i.e., it would find a minimal cost path if any path to a goal node existed. Further, we proved that if the heuristic function also satisfied something called the <u>consistency assumption,</u> then A* was <u>optimal;</u> i.e., it expanded no more nodes than any other admissible algorithm A no more informed than A*. These results were summarized in a book by one of us.