40,504 research outputs found
Network traffic modelling and router performance optimization using fuzzy logic and genetic algorithms
University of Technology, Sydney. Faculty of Information Technology.Accurate computer network traffic models are required for many network tasks
such as network analysis, performance optimization and areas of traffic engineering
such as avoiding congestion or guaranteeing a specific quality of service (QoS)
to an application. Existing traffic modelling techniques rely on precise mathematical
analysis of extensive measured data such as packet arrival time, packet
size and server-side or client-side round trip time. With the advent of high speed
broadband networks, gathering an acceptable quantity of data needed for the
precise representation of traffic is a difficult, time consuming, expensive and in
some cases almost an impossible task. A possible alternative is to employ fuzzy
logic based models which can represent processes characterized by imprecise data,
which is generally easier to gather. The effectiveness of these models has been
demonstrated in many industrial applications. This work develops fuzzy logic
based traffic models using imprecise data sets that can be obtained realistically.
Optimizing the performance of a router requires the optimization of a number of
conflicting objectives. A possible approach is to express it as a multi-objective
problem. Multi-objective evolutionary algorithms (MOEA) can be used for solving
such problems. This research proposes two fuzzy logic based traffic models:
fuzzy group model and fuzzy state model. These models together with MOEA are
used to propose a simple and fast router buffer management scheme. The developed
fuzzy group model includes a parameter which is also useful for measuring
the irregular traffic patterns known as burstiness. The experimental results are
promising
Applications of Soft Computing in Mobile and Wireless Communications
Soft computing is a synergistic combination of artificial intelligence methodologies to model and solve real world problems that are either impossible or too difficult to model mathematically. Furthermore, the use of conventional modeling techniques demands rigor, precision and certainty, which carry computational cost. On the other hand, soft computing utilizes computation, reasoning and inference to reduce computational cost by exploiting tolerance for imprecision, uncertainty, partial truth and approximation. In addition to computational cost savings, soft computing is an excellent platform for autonomic computing, owing to its roots in artificial intelligence. Wireless communication networks are associated with much uncertainty and imprecision due to a number of stochastic processes such as escalating number of access points, constantly changing propagation channels, sudden variations in network load and random mobility of users. This reality has fuelled numerous applications of soft computing techniques in mobile and wireless communications. This paper reviews various applications of the core soft computing methodologies in mobile and wireless communications
Self-tuning run-time reconfigurable PID controller
Digital PID control algorithm is one of the most commonly used algorithms in the control systems area. This algorithm is very well known, it is simple, easily implementable in the computer control systems and most of all its operation is very predictable. Thus PID control has got well known impact on the control system behavior. However, in its simple form the controller have no reconfiguration support. In a case of the controlled system substantial changes (or the whole control environment, in the wider aspect, for example if the disturbances characteristics would change) it is not possible to make the PID controller robust enough. In this paper a new structure of digital PID controller is proposed, where the policy-based computing is used to equip the controller with the ability to adjust it's behavior according to the environmental changes. Application to the electro-oil evaporator which is a part of distillation installation is used to show the new controller structure in operation
Multi-objective evolutionary–fuzzy augmented flight control for an F16 aircraft
In this article, the multi-objective design of a fuzzy logic augmented flight controller for a high performance fighter jet (the Lockheed-Martin F16) is described. A fuzzy logic controller is designed and its membership functions tuned by genetic algorithms in order to design a roll, pitch, and yaw flight controller with enhanced manoeuverability which still retains safety critical operation when combined with a standard inner-loop stabilizing controller. The controller is assessed in terms of pilot effort and thus reduction of pilot fatigue. The controller is incorporated into a six degree of freedom motion base real-time flight simulator, and flight tested by a qualified pilot instructor
Generating Interpretable Fuzzy Controllers using Particle Swarm Optimization and Genetic Programming
Autonomously training interpretable control strategies, called policies,
using pre-existing plant trajectory data is of great interest in industrial
applications. Fuzzy controllers have been used in industry for decades as
interpretable and efficient system controllers. In this study, we introduce a
fuzzy genetic programming (GP) approach called fuzzy GP reinforcement learning
(FGPRL) that can select the relevant state features, determine the size of the
required fuzzy rule set, and automatically adjust all the controller parameters
simultaneously. Each GP individual's fitness is computed using model-based
batch reinforcement learning (RL), which first trains a model using available
system samples and subsequently performs Monte Carlo rollouts to predict each
policy candidate's performance. We compare FGPRL to an extended version of a
related method called fuzzy particle swarm reinforcement learning (FPSRL),
which uses swarm intelligence to tune the fuzzy policy parameters. Experiments
using an industrial benchmark show that FGPRL is able to autonomously learn
interpretable fuzzy policies with high control performance.Comment: Accepted at Genetic and Evolutionary Computation Conference 2018
(GECCO '18
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