Showing papers in "International Journal of Systems Science in 1998"
TL;DR: Results from the first science deployment of the Autonomous Benthic Explorer (ABE) on the Juan de Fuca Ridge are summarized, which permits extrapolation of the ABE's performance to other missions and higher capacity batteries.
Abstract: This paper summarizes results from the first science deployment of the Autonomous Benthic Explorer (ABE), conducted on the Juan de Fuca Ridge (46°N, 129°W) at depths between 2200 and 2400 m. Using long baseline acoustic transponders, the ABE descended with precision to a preassigned starting point, then executed dead-reckoned tracklines. It followed the bottom at distances between 7 and 20 m using an acoustic fathometer as a reference sensor. The ABE mapped a new subsea lava flow with a magnetometer, imaged the seafloor with a stereo snapshot video system, and mapped a hydro thermal plume with conductivity and temperature sensors. The ABE completed 7 successful dives and covered over 35 km of tracklines. Detailed power records were logged, which permits extrapolation of the ABE's performance to other missions and higher capacity batteries.
79 citations
TL;DR: An application of the Kalman filter with a recursive estimator to determine the impulsive loads is presented, which is demonstrated by numerical simulations for a single-degree-of-freedom system as well as for a multiple-degree of-freedom lumped-mass system.
Abstract: This work presents an application of the Kalman filter with a recursive estimator to determine the impulsive loads. The impulsive loads are estimated from the measured dynamic response data of structures through an inverse method. The estimator employs a least-squares algorithm to compute the magnitudes and, therefore, the onset time histories of the impulsive loads. The accuracy of the present method is demonstrated by numerical simulations for a single-degree-of-freedom system as well as for a multiple-degree-of-freedom lumped-mass system, with loads and motions along a single axis
57 citations
TL;DR: An order-level inventory model is developed by assuming that the demand rate is stock-dependent and two separate warehouses are used and a sensitivity analysis is carried out by taking a numerical example.
Abstract: An order-level inventory model is developed by assuming that the demand rate is stock-dependent and two separate warehouses are used When the stock level exceeds the capacity of the own warehouse (OW), a rented warehouse (RW) is used The stock is transferred periodically in bulk from RW to OW and there is an associated transportation cost No shortages are allowed An algorithm is developed to obtain the optimal solution of the model To study the effects of changes in the system parameters on the decision variables, a sensitivity analysis is carried out by taking a numerical example
57 citations
TL;DR: An inventory model is developed for items that deteriorate continuously in time when demand is a random variable and it is assumed that the supplier allows delayed payment for settling the replenishment account.
Abstract: An inventory model is developed for items that deteriorate continuously in time when demand is a random variable. It is assumed that the supplier allows delayed payment for settling the replenishment account. The model is continuous in units but discrete in time. A numerical example is given to illustrate the derived results
55 citations
TL;DR: Two approaches to fix computation and filtering of vehicle dead-reckoned motion are presented, which consist of dead reckoning between fixes computed from a set of acoustic travel times.
Abstract: Oceanographic data acquired by an autonomous underwater vehicle (AUV) must he correlated with accurate position information in order to he of value to scientists. Accurate navigation is therefore an essential requirement which can he fulfilled by use of acoustic long-baseline navigation systems and dead-reckoning sensors. Two approaches are presented in this paper. The fix computation approach consists of dead reckoning between fixes computed from a set of acoustic travel times. The filtering approach consists of correcting the vehicle dead-reckoned motion by taking into account the influence of the measured travel times. Fix computation is widely used for the positioning of manned submersibles and there seems to be some reluctance to switch to a filler-based approach, mainly because of the fear for divergence. After a detailed description of these two approaches, their advantages and drawbacks are compared by applying both algorithms to real data sets collected by the Odyssey II AUV developed at Massachu...
52 citations
TL;DR: The efficiency effects of different forms of ownership and types of marketing system are studied using 1989 data for the US property-liability insurance industry and a use of (non-parametric) rank-order statistics produces results which differ from these other studies.
Abstract: The efficiency effects of different forms of ownership (stock versus mutual) and types of marketing system (agency versus direct) are studied using 1989 data for the US property-liability insurance industry. Data envelopment analysis (DEA) results are obtained from the recently developed RAM (Range Adjusted Measure) model and then extended for comparison with studies by others. Using agency theory (and like approaches) these studies assume that operations all occur only on the efficient frontier. The need for that assumption is obviated by using operations provided by DEA to project all observations onto their efficient frontiers. A use of (non-parametric) rank-order statistics then produces results which differ from these other studies.
52 citations
TL;DR: A novel algorithm (LOLIMOT) is proposed for the construction of Takagi-Sugeno fuzzy models that exploits the special structure of the local linear models and shows effectiveness by application to temperature control of an industrial-scale cross-flow heat exchanger.
Abstract: This paper deals with predictive control based on fuzzy models. A novel algorithm (LOLIMOT) is proposed for the construction of Takagi-Sugeno fuzzy models. The rule consequents are optimized by a local orthogonal least-squares method that selects the significant regressors. The rule premises are optimized by a tree construction algorithm which partitions the input space in hyper-rectangles. A generalized predictive controller (GPC) and a dynamic matrix controller (DMC) are designed. Both controllers require the extraction of a linear model from the Takagi-Sugeno fuzzy model. For the GPC a new technique called local dynamic linearization is proposed that exploits the special structure of the local linear models. The DMC is based on the evaluation of a step response. The effectiveness of both the identification algorithm and the predictive controllers is shown by application to temperature control of an industrial-scale cross-flow heat exchanger.
49 citations
TL;DR: A cost model subject to times to remove errors in the software system and risk cost due to software failure is developed and a software reliability model based on the non-homogeneous Poisson process is used.
Abstract: A cost model subject to times to remove errors in the software system and risk cost due to software failure is developed. A software reliability model based on the non-homogeneous Poisson process is used. The optimal release policies to minimize the expected total software cost are discussed. A software is also developed using Excel and Visual Basic tools to facilitate the task of determining the optimal software release time. Numerical examples are provided to illustrate the results.
42 citations
TL;DR: The presented variable structure controller ensures the global reaching condition of the sliding mode of the error system, and shows that the uncertain nonlinear dynamic system also possesses the property of insensitivity to uncertainties and disturbances as a linear system does.
Abstract: The problem of model-referenced control for interconnected systems with series non-linearities is investigated. By applying variable structure control theory, we propose a controller which is able to drive the error subsystem between the model state and the plant state to zero. The presented variable structure controller ensures the global reaching condition of the sliding mode of the error system. It shows that the uncertain nonlinear dynamic system also possesses the property of insensitivity to uncertainties and disturbances as a linear system does. Furthermore, the sliding mode can be designed to converge within a specified exponential speed.
40 citations
TL;DR: A new method is proposed for the asymptotically stable sliding mode observer design for SISO linear systems including disturbance inputs which may not satisfy the matching conditions.
Abstract: A new method is proposed for the asymptotically stable sliding mode observer design for SISO linear systems including disturbance inputs which may not satisfy the matching conditions. A sliding observer design method is presented such that, in the presence of the unmatched uncertainty, the estimated state nearly approaches the actual state. Certain sufficient conditions should be satisfied for the asymptotic stability of the error system. Otherwise, this method ensures only that the estimated state approximately tends to the actual state. The reaching time to the sliding surface, the sliding dynamics of the system, the stability of the reconstruction error system via the Lyapunov method, sufficient conditions for the existence of the sliding mode and the dependency of estimated state upon the magnitude of the unmatched uncertainty are studied.
39 citations
TL;DR: This paper examines the issues of volatility at the aggregate level using aggregate stock market values and aggregate after-tax net cashflow as a ratio of national income to suggest that large movements cannot be rationalized within the context of the decentralized stochastic growth paradigm.
Abstract: This paper examines the issues of volatility at the aggregate level. Rather than studying individual securities we focus on volatility utilizing aggregate stock market values and aggregate after-tax net cashflow as a ratio of national income. Our approach is in the tradition of the infinitely-lived classical growth model of Solow, where the behaviour of capital, consumption and investment are studied as shares of output. For the period 1946–1993 both the cashflows to equity and consumption as a share of national income were fairly constant. Yet there was significant movement in the value of the stock market as a share of national income. Our analysis suggests that these large movements cannot be rationalized within the context of the decentralized stochastic growth paradigm.
TL;DR: Simulation and experimental results show that the proposed MFC scheme is effective and robust against both parameter va...
Abstract: A novel model-following scheme with a simple structure for electrical position servo systems is proposed. It is quite different from and much simpler than existing model-following control (MFC) schemes. The nominal model of a plant is used as the reference model in this scheme. The common external input to the reference model and to the plant is not fed from the reference command but from a model controller which is designed for the nominal model of the plant to ensure a satisfactory reference output trajectory. The following of the plant to the reference model with the expected output trajectory is guaranteed using a correction signal from an adaptive mechanism which has a simple linear PID structure, taking only the generalized output error as its input. Conditions for asymptotic model-following are first developed rigorously and then implemented. The system design method is described. Simulation and experimental results show that the proposed MFC scheme is effective and robust against both parameter va...
TL;DR: A method is proposed to compute an exact inversion of a linguistic multiple-input single-output fuzzy model with triangular pairwise overlapping membership functions and the weighted fuzzy mean defuzzification.
Abstract: A method is proposed to compute an exact inversion of a linguistic multiple-input single-output fuzzy model with triangular pairwise overlapping membership functions and the weighted fuzzy mean defuzzification. Equations are given which describe the parameters of the inverse model as a function of the parameters of the forward model. The inverse, model can be used as a decision support tool for process operators or can directly control a process. A realistic simulation example is presented to highlight the application of the proposed method to inverse-model control in a nonlinear internal model control scheme.
TL;DR: An extension of the Lie derivative for a difference-differential equation is introduced and necessary and sufficient conditions for existence of a nonlinear feedback that linearizes the input-output behaviour of a system and decouples it from the delayed variables simultaneously.
Abstract: The present paper is concerned with nonlinear systems that contain delays inside coupled with a part of state variables, which are often the cases in practical problems, but have not been treated yet. First we introduce an extension of the Lie derivative for a difference-differential equation; then we derive necessary and sufficient conditions for existence of a nonlinear feedback that linearizes the input-output behaviour of a system and decouples it from the delayed variables simultaneously. Discussions are given for two cases: firstly when the linearizing feedback contains only current values of state variables, and secondly when the linearizing feedback has memories to utilize the past values as well as the current values of state variables.
TL;DR: This paper describes the design and implementation of a mission control system for the MARIUS autonomous underwater vehicle (AUV) using well-established tools from continuous- or discrete-time dynamic system theory, and finite-state automata to describe their logical (event-based) interaction with vehicle primitives.
Abstract: This paper describes the design and implementation of a mission control system for the MARIUS autonomous underwater vehicle (AUV). The framework adopted for system design builds on the key concept of vehicle primitive, which is a parametrized specification of an elementary operation performed by the vehicle. Vehicle primitives are obtained by coordinating the execution of a number of concurrent system tasks, which are parametrized specifications of classes of algorithms or procedures that implement basic functionalities in an underwater robotic system. Vehicle primitives are in turn logically and temporally chained to form more abstract mission procedures, which are executed as determined by mission programs, in reaction to external events. System task design is carried out using well-established tools from continuous- or discrete-time dynamic system theory, and finite-state automata to describe their logical (event-based) interaction with vehicle primitives. The design and analysis of vehicle primitives ...
TL;DR: It is proved that self crossover can generate any permutation of a given string, which satisfies this constraint as well as retaining the stochastic and evolutionary characteristics of genetic algorithms.
Abstract: Crossover is an important genetic operation that helps in random recombination of structured information to locate new points in the search space, in order to achieve a good solution to an optimization problem. The conventional crossover operation when applied on a pair of binary strings will usually not retain the total number of is in the offsprings to be the same as that of their parents, but there are many optimization problems which require such a constraint. In this article, we propose a new crossover technique called ‘self-crossover’, which satisfies this constraint as well as retaining the stochastic and evolutionary characteristics of genetic algorithms. This new operator serves the combined role of crossover and mutation. We have proved that self crossover can generate any permutation of a given string. As an illustration, the effectiveness of this new technique has been demonstrated for the feature selection problem of pattern recognition. Performance of self-crossover for feature selection is ...
TL;DR: A linear consecutive-k-out-of-n: G repairable system with k > n/2 is studied and the exact formulas of the system reliability and the system MTTFF (mean time to first failure) can be obtained.
Abstract: A linear consecutive-k-out-of-n: G repairable system with k > n/2 is studied. Assume that the working time and the repair time of the components in the system are both exponentially distributed, and every component is as good as new after repair. By using the definition of the generalized transition probability, the state transition probabilities of the system are derived. When n is given, the exact formulas of the system reliability (or its Laplace transform) and the system MTTFF (mean time to first failure) can be obtained.
TL;DR: This paper deals with the optimal filtering problem constrained to input noise signal corrupting the measurement output for linear discrete-time systems, using the transfer matrix H2 and/ or Hinfin; norms as criteria in an estimation error sense.
Abstract: This paper deals with the optimal filtering problem constrained to input noise signal corrupting the measurement output for linear discrete-time systems. The transfer matrix H2 and/ or Hinfin; norms are used as criteria in an estimation error sense. First, the optimal filtering gain is obtained from the H 2 norm state-space definition. Then the attenuation of arbitrary input signals is considered in an H ∞ setting. Using the discrete-time version of the bounded real lemma on the estimation error dynamics, a linear stable filter guaranteeing the optimal H∞ attenuation level is achieved. Finally. the mixed H 2 / H∞ filter problem is solved, yielding a compromise between the preceding filter designs. All these filter design problems are formulated in a new convex optimization framework using linear matrix inequalites. A numerical example is presented
TL;DR: Sensitivity analysis of the optimal solutions of data envelopment analysis is illustrated here by a numerical example.
Abstract: Sensitivity analysis of the optimal solutions of data envelopment analysis is illustrated here by a numerical example.
TL;DR: A new complete parametric approach for eigenstructure assignment in controllable linear descriptor systems, E[xdot] = Ax + Bu via the static state feedback control u = Kx, is proposed, and guarantees arbitrary assignment of rank(E) number finite closed-loop eigenvalues with arbitrary given algebraic and geometric multiplicities.
Abstract: A new complete parametric approach for eigenstructure assignment in controllable linear descriptor systems, E[xdot] = Ax + Bu via the static state feedback control u = Kx, is proposed. General complete parametric expressions in direct closed forms for the closed-loop eigenvectors associated with the finite closed-loop eigenvalues are presented, based on a recently proposed complete parametric solution to the generalized Sylvester matrix equation AV + BW = EVF. These expressions are linear in a group of parameter vectors which represent the degree of the design freedom. A very simple complete parametric solution for the feedback gain matrix K is also established with the help of a proposed ‘completing the square’ technique. The approach guarantees arbitrary assignment of rank(E) number finite closed-loop eigenvalues with arbitrary given algebraic and geometric multiplicities, and realizes elimination of all possible initial time impulsive responses. It also guarantees the closed-loop regularity when two si...
TL;DR: An inexact approach to solve a kind of fuzzy nonlinear programming problems (FO/RNP) by way of a special Genetic Algorithm with mutation along the weighted gradient direction with the aim of finding a family of solutions with acceptable membership degrees.
Abstract: As the extension of our previous paper (Tang and Wang 1997) for solving nonlinear programming problems, this paper focuses on a symmetric model for a kind of fuzzy nonlinear programming problems (FO/RNP) by way of a special Genetic Algorithm (GA) with mutation along the weighted gradient direction It uses an r-power type of membership function to formulate a kind of fuzzy objective and two kinds of fuzzy resource constraints which are commonly used in actual production problems The solution to FO/RNP may be transformed into the solution to three kinds of model according to different kinds of criteria preferred by the decision maker (DM) This paper develops an inexact approach to solve this type of model of nonlinear programming problems Instead of finding an exact optimal solution, this approach uses a GA with mutation along the weighted gradient direction to find a family of solutions with acceptable membership degrees Then by means of the human-computer interaction, the solutions preferred by the (DM) under different criteria can be achieved The overall procedure for FO/RNP is also developed in this paper, it may supply a preliminary framework for practical application of the FO/RNP model
TL;DR: DEA is applied, utilizing the input and output data for the years 1984–1990 from 201 banks each with assets in excess of 1 billion dollars and hence regarded as ‘large banks’ by asset-size.
Abstract: Maindiratta (1990) questioned the practical relevance of the most productive scale size (MPSS) and the associated concept of scale efficiency on the grounds that the observed output bundle of a firm or decision making unit (DMU), in many situations, is an assigned task and cannot be altered by the DMU. Also, in a market economy, the output-input combinations at the MPSS may not be economically viable. It would still be of interest to examine whether greater input saving can be achieved if the assigned output bundle is produced collectively by several banks, each operating efficiently, rather than individually by a single bank operating efficiently. In any specific case. the optimal number of smaller banks—if an existing bank should be broken up at all— is determined within a mixed integer programming model. In this study we apply DEA, utilizing the input and output data for the years 1984–1990 from 201 banks each with assets in excess of 1 billion dollars and hence regarded as ‘large banks’ by asset-size ...
TL;DR: A new nonlinear rational model identification algorithm is introduced based on genetic algorithms that provides near-optimal global parameter estimation but is balanced by an enormous computational load even when identifying models which consist of modest parameter sets.
Abstract: A new nonlinear rational model identification algorithm is introduced based on genetic algorithms, Compared with other rational model identification approaches, the new algorithm has two main advantages. First, this algorithm does not require a linear-in-the-parameters regression equation and, as a consequence, the severe noise problems induced by multiplying out the rational model are avoided. Second, the new algorithm provides near-optimal global parameter estimation. Unfortunately, this is balanced by an enormous computational load even when identifying models which consist of modest parameter sets. Simulated examples are included to illustrate that the new algorithm works well on systems with modest candidate term sets but can fail when applied to systems with large candidate term sets.
TL;DR: The obtained estimator, optimal in the unbiased minimum variance sense, is used for robust decentralized state and constant bias filtering in linear discrete-time stochastic systems with unknown inputs.
Abstract: A new approach for state filtering in linear discrete-time stochastic systems with unknown inputs is presented. The obtained estimator, optimal in the unbiased minimum variance sense, is used for robust decentralized state and constant bias filtering
TL;DR: A terrain-based underwater navigation using sonar bathymetric profiles is presented, and the formalism of partial differential equations is used to smooth depth maps in a morphologically invariant way and to obtain anisotropic contours.
Abstract: A terrain-based underwater navigation using sonar bathymetric profiles is presented. It deals with matching high-resolution local depth maps against a large on-board reference map. The matching algorithm locates the local depth map within the a priori known larger map to determine the absolute position and heading of the vehicle. Two separate approaches for this problem are presented. The first uses a contour-based representation of depth maps. Contours are extracted from both local and reference maps. Invariant attributes under rigid plane transformation are associated with each contour point, so that the problem is reduced to a point-based matching algorithm: given two point sets, find correspondences and estimate transformation between the two sets. We shall particularly focus on the formalism of partial differential equations, which is used to smooth depth maps in a morphologically invariant way and to obtain anisotropic contours. The second approach is also based on a correspondence algorithm. Here, ...
TL;DR: This paper decomposes highly reliable serial production lines into two machines and one buffer line and utilizes the decomposed lines to approximate the average steady state production rate in a closed form.
Abstract: In this paper, a model of a highly reliable serial production line is introduced and analysed. The high production rate of machines in isolation and quality inspection machines are the basis of highly reliable production lines. Using Taylor series expansion, we decompose highly reliable serial production lines into two machines and one buffer line and then utilizing the decomposed lines, approximate the average steady state production rate in a closed form. Finally, we validate the results by simulations.
TL;DR: In this article, a stable fuzzy indirect control scheme is presented for a class of interconnected nonlinear systems for which an explicit linear parametrization of the uncertainty is either unknown or impossible.
Abstract: A stable fuzzy indirect control scheme is presented for a class of interconnected nonlinear systems for which an explicit linear parametrization of the uncertainty is either unknown or impossible. In the control algorithm, fuzzy logic systems, are employed to approximate the unknown dynamics in each subsystems, the feedback and adaptation mechanisms for each subsystems depend only upon local measurements to provide asymptotic tracking of a reference trajectory. In addition, a fuzzy sliding mode controller is developed to compensate for the fuzzy approximating errors or neural network approximating, and to attenuate the interactions between subsystems. Global asymptotic stability is established in the Lyapunov sense, with the tracking errors converging to a neighbourhood of zero
TL;DR: The linear quadratic (LQ) criterion is used to derive the optimal control policy for both deterministic and stochastic demand cases and a guaranteed cost control law is proposed.
Abstract: The discrete-time inventory control problem for deteriorating items with deterministic or stochastic demand is considered. The control problem is stated as an optimization problem with constrained control variables. The linear quadratic (LQ) criterion is used to derive the optimal control policy for both deterministic and stochastic demand cases. In the presence of bounded uncertainties, a guaranteed cost control law is also proposed. A numerical example is provided to show the usefulness of the theoretical results.
TL;DR: The design of the fingertip sensing subsystem constructed for use in a dextrous underwater gripper is presented, and a simple robust device based on strain gauge technology developed specifically for this application is presented.
Abstract: The design of the fingertip sensing subsystem constructed for use in a dextrous underwater gripper is presented. Two distinct types of sensor were developed specifically for this application, a force sensor and a slip sensor. The force sensor is used to determine the force exerted by the gripper on the target object, and hence to allow the force hop closure required to carry out dextrous manipulation and to handle delicate marine samples. The function of the slip sensor is to detect the occurrence of slippage between the fingertip and the target, and this information can be used in a variety of ways: for example, providing a warning system to the force control loop or enhancing the gripper's exploratory capabilites in areas of poor visibility. Due to changes in ambient pressure, the force sensor is a simple robust device based on strain gauge technology developed specifically for this application. The sensor is capable of being incorporated on an artificial fingertip mounted at the extremity of the finger...
TL;DR: The concept of a grey predictor and a fuzzy controller will be integrated to construct a switching grey prediction fuzzy control system structure to simultaneously improve the transient and steady-state responses of the controlled system.
Abstract: The concept of a grey predictor and a fuzzy controller will he integrated to construct a switching grey prediction fuzzy control system structure. A rule mapping fuzzy controller is considered in the proposed control system so that the design of the controller is systematic and efficient. In the design of the switching grey predictor, the authors divide the system response into some regions and propose a switching mechanism so that a different forecasting step-size is given in the different region to simultaneously improve the transient and steady-state responses of the controlled system. Moreover, the authors apply simulated annealing ( SA) to find the appropriate parameter values so that the controlled system has a high control performance. Finally, simulation results of the inverted pendulum system are given to prove the efficiency of the proposed methods