Showing papers in "International Journal of Systems Science in 2006"
TL;DR: A decentralized multiple-UAV approach to monitoring the perimeter of a fire using a six degree-of-freedom dynamic model for the UAV and a numerical propagationmodel for the forest fire is developed.
Abstract: The objective of this paper is to explore the feasibility of using multiple low-altitude, short endurance (LASE) unmanned air vehicles (UAVs) to cooperatively monitor and track the propagation of large forest fires. A real-time algorithm is described for tracking the perimeter of fires with an on-board infrared sensor. Using this algorithm, we develop a decentralized multiple-UAV approach to monitoring the perimeter of a fire. The UAVs are assumed to have limited communication and sensing range. The effectiveness of the approach is demonstrated in simulation using a six degree-of-freedom dynamic model for the UAV and a numerical propagation model for the forest fire. Salient features of the approach include the ability to monitor a changing fire perimeter, the ability to systematically add and remove UAVs from the team, and the ability to supply time-critical information to fire fighters.
529 citations
TL;DR: It is shown that even with the introduction of deterioration and learning effect to job processing times, several single machine problems and several flow shop problems remain polynomially solvable, respectively.
Abstract: In this note, we consider the machine scheduling problems with the effects of deterioration and learning. In this model, job processing times are defined by functions of their starting times and positions in the sequence. The scheduling objectives are makespan (weighted) sum of completion times and maximum lateness. It is shown that even with the introduction of deterioration and learning effect to job processing times, several single machine problems and several flow shop problems remain polynomially solvable, respectively.
113 citations
TL;DR: A deterministic economic order quantity (EOQ) inventory model taking into account inflation and time value of money is developed for deteriorating items with price- and stock-dependent selling rates.
Abstract: This study applies the discounted cash flow (DCF) approach for the analysis of a replenishment problem over a finite planning horizon. Thus, a deterministic economic order quantity (EOQ) inventory model taking into account inflation and time value of money is developed for deteriorating items with price- and stock-dependent selling rates. An efficient solution procedure is presented to determine the optimal number of replenishment, the cycle time and selling price. Then the optimal order quantity and the total present value of profits are obtained. Numerical examples are presented to illustrate the proposed model and particular cases of the model are also discussed.
111 citations
TL;DR: The simulation results show that properly controlled MR dampers are effective means for vibration suppression for passenger cars.
Abstract: Magnetorheological dampers, which are semi-active devices that use MR fluids to produce controllable forces, can be used as smart actuators to reduce the vibrations of mechanical systems. The advantage of these actuators is the low power input requirements and the high output force they produce. An analytical study is performed in this article to examine the effectiveness of this type of actuator in suppressing the vibrations of a passenger car suspension system. A half-car model including passenger dynamics subjected to road disturbance is used. Two MR dampers attached to the front and back axles are used as actuators. An optimal control scheme is used to control the overall suspension system such that the vibrations of the passenger seats as well as the chassis of the car are greatly reduced or eliminated. The simulation results show that properly controlled MR dampers are effective means for vibration suppression for passenger cars.
85 citations
TL;DR: An economic order quantity model over a finite time-horizon for a deteriorating item with a quadratic, time-dependent demand, allowing shortages in inventory is developed, determined in an optimal manner so as to minimize the average system cost.
Abstract: We develop here an economic order quantity (EOQ) model over a finite time-horizon for a deteriorating item with a quadratic, time-dependent demand, allowing shortages in inventory. The rate of deterioration is taken to be time-proportional and it is assumed that shortage occurs in every cycle. The time-horizon is divided into a finite number of equal replenishment cycles. The reorder number, the interval between two successive reorders and the shortage intervals are all determined in an optimal manner so as to minimize the average system cost. The results are illustrated with the help of a numerical example. Sensitivity of the optimal solution is also studied with respect to changes in different parameter values.
72 citations
TL;DR: This paper provides two observers for nonlinear systems given in Brunovski form: the first observer is a high-gain observer with a classical output injection form, while the second is ahigh-gain observers with a q-integral path.
Abstract: The main weakness of all control methodologies is the dependency of feedbacks to full state measurements. In practical situations, measuring the states of a given system may fail because sometimes the measurements are impossible and sometimes, possible, but too expensive. Observer design for highly nonlinear dynamics is an important issue, particularly when the locally observable dynamics are not linearly observable. In such circumstances the ability to reduce the system to observable or observer form is key to observer design. This paper provides two observers for nonlinear systems given in Brunovski form. The first observer is a high-gain observer with a classical output injection form, while the second is a high-gain observer with a q-integral path. Finally, the discrete-time implementation of the high-gain observer is discussed in linear matrix inequality framework. A motivating example is shown to highlight the efficacy of the developed observers.
69 citations
TL;DR: It is proved that the stability of the anti-windup compensator loop is equivalent to a purely discrete-time problem, while a hybrid induced norm is used for performance recovery.
Abstract: The anti-windup (AW) problem is formulated in discrete time using a configuration which effectively decouples the nominal linear and nonlinear parts of a closed loop system with constrained plant inputs. Conditions are divided which ensure an upper bound on the induced l2 norm of a certain mapping which is central to the anti-windup problem. Results are given for the full-order case, where a solution always exists, and for static and low-order cases, where a solution does not necessarily exist, but which is often more appealing from a practical point of view The anti-windup problem is also framed and solved for continous-time systems under sampled-data control. It is proved that the stability of the anti-windup compensator loop is equivalent to a purely discrete-time problem, while a hybrid induced norm is used for performance recovery. The performance problem is solved using linear sampled-data lifting techniques to transpose the problem into the purely discrete domain. The results of the paper are demonstrated on a flight control example.
60 citations
TL;DR: Comparison results show that the proposed CORE produces comprehensive and good classification rules for most datasets, which are competitive as compared with existing classifiers in literature.
Abstract: One of the major challenges in data mining is the extraction of comprehensible knowledge from recorded data. In this paper, a coevolutionary-based classification technique, namely COevolutionary Rule Extractor (CORE), is proposed to discover classification rules in data mining. Unlike existing approaches where candidate rules and rule sets are evolved at different stages in the classification process, the proposed CORE coevolves rules and rule sets concurrently in two cooperative populations to confine the search space and to produce good rule sets that are comprehensive. The proposed coevolutionary classification technique is extensively validated upon seven datasets obtained from the University of California, Irvine (UCI) machine learning repository, which are representative artificial and real-world data from various domains. Comparison results show that the proposed CORE produces comprehensive and good classification rules for most datasets, which are competitive as compared with existing classifiers ...
59 citations
TL;DR: An inventory model is derived by assuming constant rate of deterioration of units in an inventory, time value of money under the conditions of permissible delay in payments, and the optimal replenishments and fraction of cycle time to minimize the present value of inventory cost over a finite planning horizon.
Abstract: In this article, an inventory model is derived by assuming constant rate of deterioration of units in an inventory, time value of money under the conditions of permissible delay in payments. The optimal replenishments and fraction of cycle time are decision variables to minimize the present value of inventory cost over a finite planning horizon. The sensitivity analysis is carried out by a numerical example.
56 citations
TL;DR: The paper addresses the problem of steering a fleet of wheeled robots along a set of given spatial paths, while keeping a desired inter-vehicle formation pattern, using a simple algorithm that builds on linearization techniques and gain scheduling control theory.
Abstract: The paper addresses the problem of steering a fleet of wheeled robots along a set of given spatial paths, while keeping a desired inter-vehicle formation pattern. This problem arises for example when multiple vehicles are required to scan a given area in cooperation. In a possible mission scenario, one of the vehicles acts a leader and follows a path accurately, while the other vehicles follow paths that are naturally determined by the formation pattern imposed. The paper solves this and other related problems using a simple algorithm that builds on linearization techniques and gain scheduling control theory. Using this set-up, path following (in space) and inter-vehicle coordination (in time) are almost decoupled. Path following for each vehicle amounts to reducing a conveniently defined generalized error vector to zero. Vehicle coordination is achieved by adjusting the speed of each of the vehicles along its path, according to information on the position of all or some of the other vehicles. No other in...
54 citations
TL;DR: By constructing appropriate Lyapunov–Krasovskii functionals (LKF) and applying the model transformation of time-delay systems, a design scheme of state feedback controller for a class of feedforward nonlinear systems with a delay in the input is proposed.
Abstract: In this paper, by constructing appropriate Lyapunov-Krasovskii functionals (LKF) and applying the model transformation of time-delay systems, a design scheme of state feedback controller for a class of feedforward nonlinear systems with a delay in the input is proposed. The designed controllers have a very simple structure and do not involve any saturation or recursive computation, which is widely applied in designing a controller of feedforward nonlinear systems. Using the transformation of coordinates and the property of Hurwitz polynomial, the problem of designing controller can be converted into the problem of finding a parameter, which can be solved by solving the optimization problem with linear matrix inequalities (LMIs) constraints. A simulation example is given to show the effectiveness of the proposed design procedure.
TL;DR: The proposed method is based on plotting the stability boundary locus in the (kp , ki )-plane and then computing the stabilizing values of the parameters of a PI controller for a given control system, and does not require sweeping over the parameters.
Abstract: In this paper, a new method for the calculation of all stabilizing PI controllers is given. The proposed method is based on plotting the stability boundary locus in the (kp , ki )-plane and then computing the stabilizing values of the parameters of a PI controller for a given control system. The technique presented does not require sweeping over the parameters and also does not need linear programming to solve a set of inequalities. Thus, it offers several important advantages over existing results obtained in this direction. The proposed method is also applied for computation of all stabilizing PI controllers for multi-input multi-output (MIMO) control systems with consideration given to two-input two-output (TITO) systems using decoupling technique. Beyond stabilization, the method is used to compute all stabilizing PI controllers which achieve user-specified gain and phase margins. Furthermore, the method is extended to tackle 3-parameters PID controllers. The limiting values of PID controller paramete...
TL;DR: A simulation example shows that the proposed coordination mechanism improves the supply-chain performance compared to a traditional management approach, where both problems are considered separately.
Abstract: This paper introduces a new multi-agent approach for collaborative management of logistic and supply systems based on the ant colony optimisation (ACO) meta-heuristic. The logistic system and its suppliers can be modelled as partners of a supply chain. The management methodology is defined as a set of distributed scheduling problems that exchange information during the optimisation process. Each problem is solved by an ant colony agent that uses the pheromone matrix as the communication platform. A simulation example shows that the proposed coordination mechanism improves the supply-chain performance compared to a traditional management approach, where both problems are considered separately.
TL;DR: Based on the modelling of the closed-loop system resulting from the controller plus the anti-windup loop as a linear system with dead-zone and dynamics restricted nonlinearities, LMI stability conditions are formulated and numerical optimization procedures are discussed.
Abstract: This paper addresses the problem of determination of stability regions for linear systems with amplitude and successive dynamics restricted actuator through anti-windup strategies. Considering a linear dynamic output feedback designed with respect to the linear system (without saturation), an anti-windup design method is investigated to guarantee both the stability of the closed-loop system and the respect of the controlled output constraints for a region of admissible initial states as large as possible. Based on the modelling of the closed-loop system resulting from the controller plus the anti-windup loop as a linear system with dead-zone and dynamics restricted nonlinearities, LMI stability conditions are formulated. Numerical optimization procedures are discussed.
TL;DR: This study develops an EOQ model with a fuzzy inflation rate and fuzzy deterioration rate, and a delay in payment is also permissible, and the corresponding fuzzy cost function is derived.
Abstract: Through the investigation of an Economic Order Quantity (EOQ) model, it has been observed that the estimated inventory cost and starting time inventory cost are not necessarily the same. This arises as a result of the time gap in between the time of estimation and the starting time of the EOQ system, and a permissible delay in payment will affect the inventory total cost. Moreover, the political instability or uncertainty of a country (as well as the whole world) leads to a much more unstable situation in the present world economy. Thus, a change in inflation takes place, and the inflation rate is uncertain in nature. This study develops an EOQ model with a fuzzy inflation rate and fuzzy deterioration rate, and a delay in payment is also permissible. We have derived the corresponding fuzzy cost function, and the solution procedure has been explained with the help of a numerical example. A sensitivity analysis has also been carried out.
TL;DR: This paper addresses the problem of designing nonlinear observers for dynamical discrete-time systems with both constant and time-varying delay nonlinearities with structured uncertainties by assuming the existence of the observer-gain.
Abstract: In this paper, we address the problem of designing nonlinear observers for dynamical discrete-time systems with both constant and time-varying delay nonlinearities. The nonlinear system is assumed to verify the usual Lipschitz condition that permits us to transform the nonlinear system into a linear time-delay system with structured uncertainties. The existence of the observer-gain is ensured by the solution of a one linear matrix inequality. An illustrative example is included to demonstrate the advantage of the proposed observation technique.
TL;DR: Wavelet based non-parametric additive NARX models, combined with model order determination and variable selection approaches, are capable of handling problems of high dimensionality.
Abstract: Wavelet based non-parametric additive NARX models are proposed for nonlinear input-output system identification. By expanding each functional component of the non-parametric NARX model into wavelet multiresolution expansions, the non-parametric estimation problem becomes a linear-in-the-parameters problem, and least-squares-based methods such as the orthogonal forward regression (OFR) approach, coupled with model size determination criteria, can be used to select the model terms and estimate the parameters. Wavelet based additive models, combined with model order determination and variable selection approaches, are capable of handling problems of high dimensionality.
TL;DR: This paper shows how a Multiobjective Genetic Algorithm (MOGA) could find an improved Pareto-optimal front compared to the LMI approach.
Abstract: The multiobjective problems of H 2 optimal control (LQG case) and mixed H 2/H ∞ are addressed using two different approaches: Evolutionary Algorithms and Linear Matrix Inequalities (LMIs). This study illustrates with numerical examples how both approaches can be used to find the trade-off between different signal sensitivities to noise and to find the trade-off of the mixed H 2/H ∞ problem. For the mixed H 2/H ∞ example, this paper shows how a Multiobjective Genetic Algorithm (MOGA) could find an improved Pareto-optimal front compared to the LMI approach.
TL;DR: This paper shows how to choose a linear difference inclusion (LDI) in such a way that the conservativeness in the estimation is reduced, and provides an algorithm that estimates the domain of attraction of the non-linear system.
Abstract: The domain of attraction of a given non-linear system constitutes a zone of safe operation that can avoid unnecessary operational restrictions. In this paper, an alternative approach to the estimation of the domain of attraction of a saturated linear system is presented. Given a system with m saturated control inputs, we show how to choose a linear difference inclusion (LDI) in such a way that the conservativeness in the estimation is reduced. For that purpose, an LMI problem with 2 m + m constraints must be solved. In this paper, an algorithm that estimates the domain of attraction of the non-linear system is provided. Moreover, sufficient conditions to guarantee that the proposed algorithm obtains the greatest domain of attraction for the linear difference inclusion are given. Some illustrative examples are presented.
TL;DR: Under reasonable conditions, the closed form optimal control of a cost minimization problem and a profit maximization problem is derived and these derived analytical solutions yield good insight on how production planning tasks can be carried out.
Abstract: This paper is concerned with the problem of controlling the production rate of a production inventory system with deteriorating items. Under reasonable conditions, we derive the closed form optimal control of a cost minimization problem and a profit maximization problem. The derived analytical solutions yield good insight on how production planning tasks can be carried out. In addition, they also provide guidelines for further study and development of numerical methods for more complex systems involving more general exogenous functions.
TL;DR: A method for the analysis of a series-parallel safety-critical system where the system states can be distinguished into failure-safe and failure-dangerous, which incorporates the Markov chain and universal generating function technique is presented.
Abstract: This paper presents a method for the analysis of a series-parallel safety-critical system where the system states can be distinguished into failure-safe and failure-dangerous. The method incorporates the Markov chain and universal generating function technique. In the model considered, both periodic inspection and repair (perfect and imperfect) of system elements are taken into account. The system state distributions and the overall system safety function are derived, based on the developed model. The proposed method is applicable to complex systems for analysing state distributions and it is also useful in decision-making such as determining the optimal proof-test interval or repair resource allocation. An illustrative example is given.
TL;DR: Efficient algorithms which have been developed after carrying out an exhaustive study of methods such as amplitude zone time epoch coding (AZTEC), modified AZTEC, Fan and scan along polygonal approximation (SAPA) techniques and promise wider scope for application in telemedicine.
Abstract: Several techniques have been developed during the last four decades for the compression of ECG signal. The ECG signal compression is required for two main reasons, effective and economic data storage and on-line transmission of the signal. However, in present information technology (IT) the ECG data compression has become more significant for Telemedicine. Hence, it is essential to review the existing direct data compression (DDC) techniques for the purpose of telemedicine. This paper deals with efficient algorithms which have been developed after carrying out an exhaustive study of methods such as amplitude zone time epoch coding (AZTEC), modified AZTEC, Fan and scan along polygonal approximation (SAPA) techniques. In each of these techniques, modifications have been made to make it suitable for telemedicine purposes. Suitability of the system has been checked over transport control protocol (TCP), internet protocol (IP), local area network (LAN) and wide area network (WAN). The techniques have been tested for all standard leads of ECG signal of CSE database. The results of improved direct data compression techniques are encouraging and promise wider scope for application in telemedicine.
TL;DR: This study addresses the identification of linear time varying systems by based on the expansion of all time functions in the state equations by Haar wavelets, a set of complete, orthogonal basis and is easy to use computations.
Abstract: This study addresses the identification of linear time varying systems. The identification is based on the expansion of all time functions in the state equations by Haar wavelets. The unknown time function can thus be identified in terms of Haar wavelets. A Haar wavelet is a set of complete, orthogonal basis and is easy to use computations. Several good properties of Haar wavelets are utilized in the algorithm. Both numerical and experimental results verify the analysis.
TL;DR: This paper introduces a new approach for the identification of coupled map lattice models of complex spatio-temporal patterns from measured data using B-spline wavelet and scaling functions.
Abstract: This paper introduces a new approach for the identification of coupled map lattice models of complex spatio-temporal patterns from measured data. The nonlinear functionals describing the evolution of the spatio-temporal patterns are constructed using B-spline wavelet and scaling functions. This provides a multiresolution approximation for the underlying spatio-temporal dynamics. An orthogonal least squares algorithm is used to determine the suitable terms from wavelet functions to form an accurate representation of the nonlinear spatio-temporal dynamics. Three examples are used to demonstrate the application of the proposed new approach.
TL;DR: In this paper, a cold standby repairable system consisting of two identical components and one repairman is studied and it is proved under some mild conditions that the optimal policy N* is better than the optimalpolicy T*.
Abstract: In this paper, a cold standby repairable system consisting of two identical components and one repairman is studifed. Assume that each component after repair is not "as good as new", by using a geometric process, we consider two kinds of repair replacement policy, one based on the working age T of component 1 under which the system is replaced when the working age of component 1 reaches T, and the other based on the failure number N of component 1 under which the system is replaced when the failure number of component 1 reaches N. Our problem is to choose optimal replacement policies T* and N* respectively such that the long-run average cost per unit time of the system is minimized. And we can prove under some mild conditions that the optimal policy N* is better than the optimal policy T*. Finally, a numerical example for policy N is given.
TL;DR: A convex approximation of the non-convex constraints leading to constructive design algorithms for the design of full-authority and external linear anti-windup compensators of reduced order guaranteeing finite global gain is proposed.
Abstract: In this paper we provide algorithms based on Linear Matrix Inequalities for the design of full-authority and external linear anti-windup compensators of reduced order guaranteeing finite global L2 gain. Previous results showed that the reduced order anti-windup design problem is non-convex. We propose here a convex approximation of the non-convex constraints leading to constructive design algorithms. The proposed algorithms are successfully tested on two simulation examples taken from the literature.
TL;DR: This work presents an interactive fuzzy linear programming (FLP) approach for solving project management (PM) decision problems in a fuzzy environment that attempts to minimize total costs with reference to direct, indirect and penalty costs, durations of activities, specified project completion time and total allocated budget.
Abstract: This work presents an interactive fuzzy linear programming (FLP) approach for solving project management (PM) decision problems in a fuzzy environment. The proposed approach attempts to minimize total costs with reference to direct, indirect and penalty costs, durations of activities, specified project completion time and total allocated budget. A numerical example demonstrates the feasibility of applying the proposed FLP approach to actual PM decision problems. Accordingly, the proposed approach yields an efficient solution and determines the overall degree of decision maker (DM) satisfaction. Moreover, the proposed approach offers a systematic framework that facilitates the decision-making process, enabling a DM to interactively modify the range of the results when the environment data are vague until a satisfactory solution is obtained. In particular, several significant characteristics of the proposed FLP approach are elucidated in contrast to those of the main PM decision methods.
TL;DR: In this paper, the customer–producer–employment model is examined with the fuzzy system dynamics in two types of fuzzy arithmetic, α-cut fuzzy arithmetic and Tω weakest t-norm operator, and it is revealed that both types can provide the steady-state analysis of the system's variables as their counterpart, the crisp arithmetic analysis.
Abstract: This paper presents a system dynamics analysis based on the application of fuzzy arithmetic. Traditional crisp system dynamics observe that some variables/parameters may belong to the uncertain factors. It is necessary to extend the system dynamics to treat also the vague variables/parameters. The evaluation of fuzzy system dynamics may provide the decision-maker information regarding the system's behavior uncertainties. In this paper, the customer–producer–employment model is examined with the fuzzy system dynamics in two types of fuzzy arithmetic, α-cut fuzzy arithmetic and Tω weakest t-norm operator. Symmetrical and nonsymmetrical triangular fuzzy number (TFN), varied amount of fuzzy inputs’ fuzziness, and length of the system time delay are examined with useful results provided. Particularly, it is revealed that (1) both types of fuzzy arithmetic can provide the steady-state analysis of the system's variables as their counterpart, the crisp arithmetic analysis. (2) The α-cut arithmetic realizes the fu...
TL;DR: A windup prevention method guaranteeing stability for stable and unstable MIMO systems with input saturation based on a closed loop structure consisting of a feedforward part for reference signal tracking and a feedback part for system stabilization and for disturbance rejection.
Abstract: Presented is a windup prevention method guaranteeing stability for stable and unstable MIMO systems with input saturation. It is based on a closed loop structure consisting of a feedforward part for reference signal tracking and a feedback part for system stabilization and for disturbance rejection. The feedforward control uses a nonlinear model based reference filter, shaping arbitrary reference signal inputs such that only the safely applicable signals are transferred to the plant. Furthermore, the plant input signals generated are confined to predefined amplitude limits. Thus the new approach allows one to reserve part of the limited input amplitudes for disturbance attenuation and to use only the remaining part for the reference tracking. The reference shaping filter also yields a systematic prevention of the directionality problem. Two examples demonstrate the design procedure and the results achievable.
TL;DR: An appropriate measure of the distance from bad sets, suitable for multirobot navigation, is introduced and the derived closed form analytic solution provides a feedback-based navigation scheme suitable for implementation, with theoretically guaranteed global convergence and collision avoidance properties.
Abstract: In this paper, an on-line multirobot navigation methodology is presented, extending the concept of navigation functions from the single-point-sized holonomic robot domain to the domain of multiple non-point-sized holonomic robots. An appropriate measure of the distance from bad sets, suitable for multirobot navigation, is introduced. The derived closed form analytic solution provides a feedback-based navigation scheme, suitable for implementation, with theoretically guaranteed global convergence and collision avoidance properties. The proposed methodology is validated through non-trivial simulations.