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OPTIMAL CONTROLLED ALOHA FOR 2-WAY DATA COMMUNICATION IN A CABLE-TELEVISION NETWORK

IEEE TRANSACTIONS ON COMMUNICATIONS 1994年第7期42卷 2453-2459页

作者： VANDERVLEUTEN, RJ VANETTEN, WC VANDENBOOM, HPA EINDHOVEN UNIV TECHNOL FAC ELECT ENGNDEPT ELECT ENGNDIV TELECOMMUNTELECOMMUN SECT5600 MB EINDHOVENNETHERLANDS

Based on a unified analysis of both pure and slotted ALOHA systems, a new control algorithm for ALOHA systems is proposed. A feature of great practical importance is the algorithm's automatic adjustment to changes in average traffic intensity or the (finite or infinite) number of active stations in the system. In addition, the algorithm has a low-complexity implementation. computer simulations, concentrating on the use for two-way data communication in a cable television network, have demonstrated that the practical performance of the algorithm closely approximates the theoretical optimum, even under extremely heavy traffic load conditions. Furthermore, dynamic performance simulations have shown that the algorithm assures swift recovery from overload situations.

关键词： Finite Traffic density data communication algorithms Bidirectional automatic control Cable television Transportation load computer algorithms

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FLEXIBLE SPACESTRUCTURE CONTROL VIA MOVING-BANK MULTIPLE MODEL algorithms

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 1994年第3期30卷 750-757页

作者： GUSTAFSON, JA MAYBECK, PS Department of Electrical and Computer Engineering Air Force Institute of Technology OH USA

The development and performance of moving-bank multiple model adaptive control (MMAC) algorithms for quelling vibrations induced in the SPICE 2 space structure are presented. The structure consists of a large platform and a smaller platform connected by three legs in a tripod fashion. Deviations of the line-of-sight (LOS) vector from the center of the large platform to the center of the smaller platform are used for LQG controller performance evaluation. The parameter estimator implements the maximum entropy with identity covariance (ME/I) algorithm;the moving bank logic employs parameter position monitoring the controller uses the modified MMAC method. Whereas parameter variations of two percent caused instabilities in the single filter/controller design, the MMAC algorithm provides an excellent method to estimate a wide range of parameter variations and to quell oscillations in the structure.

关键词： Kalman filters adaptive control aerospace computer control aerospace computing entropy filtering and prediction theory oscillations parameter estimation performance evaluation MMAC algorithm SPICE 2 space structure adaptive control algorithms flexible sp Parameter estimation Maximum entropy Performance Evaluation CONSTRUCTION IN SPACE adaptive control Platform entropy multi-model adaptive control computer algorithms aerospace computing Kalman filters parameter variation

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HEURISTIC AND STATISTICAL algorithms FOR AUTOMATED EMISSION SPECTRAL BACKGROUND INTENSITY ESTIMATION

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APPLIED SPECTROSCOPY 1994年第8期48卷 915-925页

作者： SALIT, ML COLLINS, JB YATES, DA MACBETH PROC MEASUREMENTS NEWBURGHNY 12550 PERKIN ELMER CORP NORWALKCT 06859

Two algorithms for the complete automation of background estimation in ICP emission spectroscopy are presented and evaluated. One of these algorithms is based on heuristic spectral interpretation, while the other is based on statistical spectral interpretation. These algorithms both address the weaknesses of the conventionally employed approaches of blank subtraction in calibration and background estimation through interpolation from analyst-selected wavelengths adjacent to the analyte peak. In a rigorous evaluation with synthetic spectra, these algorithms are characterized for performance in terms of accuracy, precision, and robustness. As a demonstration of the algorithms' performance with experimentally measured spectra, a determination of uranium in the presence of a calcium background interference is performed. These algorithms require no analyst interaction for their operation, and they estimate the background for every spectrum measured.

关键词： EMISSION SPECTROSCOPY SPECTRAL INTERPRETATION BACKGROUND CORRECTION BASE-LINE FITTING computer algorithms SYNTHETIC SPECTRA EXPERIMENTS INDUCTIVELY COUPLED PLASMA

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DERIVING PROGRAMS USING GENERIC algorithms

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IBM SYSTEMS JOURNAL 1994年第1期33卷 158-181页

作者： YAKHNIS, VR FARRELL, JA SHULTZ, SS IBM Large Scale Computing Division Endicott NY

We suggest a new approach to the derivation of programs from their specifications. The formal derivation and proof of programs as is practiced today is a very powerful tool for the development of high-quality software. However, its application by the software development community has been slowed by the amount of mathematical expertise needed to apply these formal methods to complex projects and by the lack of reuse within the framework of program derivation. To address these problems, we have developed an approach to formal derivation that employs the new concept of generic algorithms. A generic algorithm is one that has (1) a formal specification, (2) a proof that it satisfies this specification, and (3) generic identifiers representing types and operations. It may have embedded program specifications or pseudocode instructions describing the next steps in the stepwise refinement process. Using generic algorithms, most software developers need to know only how to pick and adapt them, rather than perform more technically challenging tasks such as finding loop invariants and deriving loop programs. The adaptation consists of replacing the generic identifiers by concrete types and operations. Since each generic algorithm can be used in the derivation of many different programs, this new methodology provides the developer with a form of reuse of program derivation techniques, correctness proofs, and formal specifications.

关键词： computer algorithms SOFTWARE engineering

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COORDINATING LOCOMOTION AND MANIPULATION OF A MOBILE MANIPULATOR

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 1994年第6期39卷 1326-1332页

作者： YAMAMOTO, Y YUN, XP General Robotics and Active Sensory Perception(GRASP) Laboratory University of Pennsylvania Philadelphia PA USA

A mobile manipulator in this study is a manipulator mounted on a mobile platform. Assuming the end point of the manipulator is guided, e.g., by a human operator to follow an arbitrary trajectory, it is desirable that the mobile platform is able to move as to position the manipulator in certain preferred configurations. Since the motion of the manipulator is unknown a priori, the platform has to use the measured joint position information of the manipulator for its own motion planning. This paper presents a control algorithm for the platform so that the manipulator is always positioned at the preferred configurations measured by its manipulability. Simulation results are presented to illustrate the efficacy of the algorithm. The algorithm is also implemented and verified on a real mobile manipulator system. The use of the resulting algorithm in a number of applications is also discussed.

关键词： dynamics feedback matrix algebra path planning position control feedback control joint position information locomotion coordination manipulability mobile manipulator mobile platform motion planning robots Feedback moving platform Position control feedback control computer algorithms matrix algebra dynamics Path planning POSITION INFORMATION motion planning Platform maneuverability Robot Manipulators Mobile manipulator

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FUZZY CONTROL FOR A NONLINEAR MIMO PLANT SUBJECT TO CONTROL CONSTRAINTS

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IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS 1994年第10期24卷 1565-1571页

作者： STEYN, WH Department of Electrical and Electronic Engineering University of Stellenbosch Stellenbosch South Africa

A rule based fuzzy controller is presented for attitude stabilization of a small satellite in low earth orbit. Active control is done by using 3-axis magneto-torquing. A prefered torque vector can not always be generated from the magnetic coils in certain regions of the orbit, due to an unfavourable direction of the geomagnetic field vector. The main objective of an acceptable control algorithm will then be to optimize the control effort: maximize the desired influence on the controlled axis and minimize the undesired disturbances to the other axes. It was found that a fuzzy controller can achieve these goals in a computationally effective way, compared to other more involved MIMO algorithms, while performing just as well or better under similar conditions. This fuzzy controller solves the control constraint problem by chosing the best magneto- torquer, the polarity and switching instances.

关键词： Fuzzy Constraint Controllers polarity active control magnetic coils computer algorithms small satellites FUZZY CONTROLLER multiple input multiple output systems Fuzzy control

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ROBUSTNESS OF UNMODIFIED STOCHASTIC ADAPTIVE-CONTROL algorithms

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 1994年第2期39卷 396-400页

作者： RADENKOVIC, MS BIALASIEWICZ, JT Department of Electrical Engineering University of Colorado Denver Denver CO USA

Originally, adaptive control theory was developed for the ideal system models, i.e., linear system models under the assumption that relative degree and upper bounds on the order of the systems are known. At the beginning of the last decade, adaptive control algorithms designed for such ideal system models were strongly attacked by many researchers due to ''lack of robustness'' in the presence of unmodeled dynamics and external disturbances. The purpose of the present paper is to relax existing constant pressure on the adaptive control algorithms originally designed for the ideal system models. It is shown that such adaptive control algorithms are globally stable and robust with respect to unmodeled dynamics and external disturbances without any modifications, such as isigma-modification, epsilon1-modification, relative dead-zone, projection of the parameter estimates, etc. Global stability of the unmodified algorithms is established by requiring the reference signal to be persistently exciting.

关键词： adaptive control linear systems stability stochastic systems external disturbances global stability linear system persistently exciting reference signal robustness unmodeled dynamics unmodified stochastic adaptive control algorithms external disturbance unmodeled dynamics adaptive control algorithms Linear system stochastic systems overall buckling Robustness computer algorithms

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A RECURSIVE CONCENTRATOR STRUCTURE WITH APPLICATIONS TO SELF-ROUTING SWITCHING-NETWORKS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1994年第2-4期42卷 896-898页

作者： NARASIMHA, MJ STAR Laboratory Department of Electrical Engineering University of Stanford Stanford CA USA

A technique for constructing an N-input concentrator from two (N/2)-input concentrators and a stage of 2x2 switching elements is described. Recursive decomposition of each of the (N/2)-input concentrators yields a log2N-stage switching network similar in topology to the inverse omega network. The control algorithm for setting the switching elements is shown to be a simple logic function of the activity bits of the inputs. An iterative cell that combines the functions of the control logic and the 2x2 switching element can be used as a building block to realize the entire concentrator. Applications of the concentrator structure as an interconnection fabric in fast packet switching is explored. This leads to an efficient self-routing network, similar in topology to the transposed Batcher-banyan network.

关键词： topology Switching networks concentrators(telecommunications) control logic multistage interconnection networks Switch elements Recursive Network computer algorithms

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OPTIMAL FLOW-CONTROL OF AN M/M/1 QUEUE WITH A BALANCED BUDGET

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 1994年第9期39卷 1918-1921页

作者： CHAKRAVORTI, B BELLCORE INFORMAT SCI & TECHNOL LABECON RES GRPMORRISTOWNNJ

The following problem is considered. There are several users who send jobs to an M/M/1 queue and have privately observed information relating to their benefits from the rate of job submissions and their costs due to waiting in the queue. Each user's benefits and costs are unknown to the queue manager and to other users. The manager's objective is to achieve ''optimal'' flow control, where the optimality depends on arriving at an appropriate trade-off between delay and the job arrival rate assigned to each user: the allocations should be such that no user can be made better off by a reallocation without hurting at least one other user. Since the optimality calculation requires knowledge of the users' private information, we propose an algorithm that converges to the optimum, while inducing users to reveal information relating to their benefits and costs truthfully, and balances the manager's budget. Earlier work on this problem [1] has produced a flow control algorithm that requires the queue manager to incur a potentially huge deficit;this leads to several theoretical and practical problems.

关键词： flow control manager jobs PLXNB2 gene Queue Budgets Cost Benefit optimality computer algorithms

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STRICTLY NONBLOCKING 512X512 OPTICAL-FIBER MATRIX SWITCH BASED ON 3-STAGE CLOS NETWORK

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IEEE PHOTONICS TECHNOLOGY LETTERS 1994年第6期6卷 764-766页

作者： TACHIKURA, M KATAGIRI, T KOBAYASHI, H NTT Telecommunication Field Systems Research and Development Center Tokaimura Ibaraki Japan

This letter describes a novel structure for large-matrix connector-type optical switches. The dimensions of the apparatus designed for 512 x 512 switching were 0.8 m(W) x 0.6 m(D) x 1.85 m(H). It is based on the three-stage Clos network. Switching is accomplished by the mechanical reconnection of fibers. The fiber tangling is avoided by using an intelligent zigzag transfer method for the connector plugs. The mean insertion loss is less than 1 dB for SM fibers. The most appropriate internal fiber link is chosen by a computer algorithm from all possible candidates. The mean switching time is estimated at about 1 min.

关键词： Strictly Fiber Optical Fibers multistage interconnection networks computer algorithms tangling Connector Device Component fiber optic link Switches

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