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MAXIMUM-LIKELIHOOD SOFT DECODING OF BINARY BLOCK-CODES AND DECODERS FOR THE GOLAY CODES

IEEE TRANSACTIONS ON INFORMATION THEORY 1989年第5期35卷 963-975页

作者： SNYDERS, J BEERY, Y Department of Electronic Communications Control and Computer Systems School of Engineering Tel-Aviv University Ramat-Aviv Israel Dept. of Electron. Commun. Control & Comput. Syst. Tel-Aviv Univ. Ramat-Aviv Israel

Maximum-likelihood soft-decision decoding of linear block codes is addressed. A binary multiple-check generalization of the Wagner rule is presented, and two methods for its implementation, one of which resembles the suboptimal Forney-Chase algorithms, are described. Besides efficient soft decoding of small codes, the generalized rule enables utilization of subspaces of a wide variety, thereby yielding maximum-likelihood decoders with substantially reduced computational complexity for some larger binary codes. More sophisticated choice and exploitation of the structure of both a subspace and the coset representatives are demonstrated for the (24, 12) Golay code, yielding a computational gain factor of about 2 with respect to previous methods. A ternary single-check version of the Wagner rule is applied for efficient soft decoding of the (12, 6) ternary Golay code.< >

关键词： Maximum likelihood decoding Block codes Lattices Computational complexity Binary codes Information theory Parity check codes Maximum likelihood detection Conferences Communication system control

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Soft decision decoding of block and lattice codes 16

Soft decision decoding of block and lattice codes

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16th Conference of Electrical and Electronics Engineers in Israel, EEIS 1989

作者： Be'ery, Yair Department of Electronic Communications Control and Computer Systems School of Engineering Tel-Aviv University Ramat-Aviv69978 Israel

Maximum likelihood soft decision decoding of block and lattice codes has recently gained renewed interest. This is partially due to the major role of block and lattice codes in block-coded modulation techniques for band limited channels [1],[2], and in part because of the feasibility of practical implementation of such sophisticated decoders due to the recent rapid progress in VLSI and DSP (digital signal processor) technologies. Most notably, the decoding algorithms derived by Conway & Sloane [3], Be'ery & Snyders [4], and Forney [5] are considerably more efficient than results published earlier [6]-[9]. The decoding procedures in the foregoing papers are presented with the aid of different tools, namely tables in [3], Hadamard transform in [4] and trellises in [5]. Nevertheless, they rely on an identical idea: decoding each coset of a subcode of certain types, in combination with the Wagner rule [6] or a generalized Wagner rule [11], when appropriate. Thus we may use the term 'Coset-Decoding' to identify the common approach of these methods. These decoders are practically implementable for various codes, like Reed-Muller codes [4],[5] and related lattice codes [5], binary [3]-[5],[10] and ternary [11],[12] Golay codes, and the related Leech lattice code [3],[5],[14],[15], Hamming and BCH codes [4],[11],[13], the non-linear Nordstrom-Robinson code [5],[16],[17], and many other lattice codes [S],[12]. © 1990 IEEE.

关键词： Maximum likelihood

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Optimum Algebraic Design of Continuous-Time Regulators with Polyhedral Constraints

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IFAC Proceedings Volumes 1989年第6期22卷 291-294页

作者： M. Vassilaki G. Bitsoris AMBER S.A.Computer Systems POB3500 Athens.Greece Control Systems Laboratory.Electrical Engineering Department University of patras 26500 Patras Greere

In this paper, the Linear Constrained Regulation Problem for continuous-time systems will be studied and a design algorithm for a linear constrained feedback controller will be developed. Both state and control vectors are assumed to be subjected to linear constraints The approach presented, is based on the notion of positive invariance of polyhedral sets. Existence conditions for a control law that transfers asymptotically to the origin all initial states in a polyhedral subset of the state space is formulated. Then, a solution to the LCRP is derived solving a non-linear optimization problem

关键词： Linear systems stability positively invariant sets optimisation

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Reconfigurable flight controller for the STOL F-15 with sensor/actuator failures

Reconfigurable flight controller for the STOL F-15 with sens...

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IEEE National Conference on Aerospace and Electronics (NAECON)

作者： D.L. Pogoda P.S. Maybeck Advanced Flight Control Unit of the Aircraft Control Systems Department General Electric Company Limited Department of Electrical and Computer Engineering Air Force Institute of Technology OH USA

A multiple model adaptive controller that provides for reconfiguration in response to sensor and/or actuator failures is developed for an approach and landing profile for the short take-off and landing (STOL) F-15 aircraft. Each elemental controller within the multiple model controller is based on a command generator tracker/proportional plus integral/Kalman filter design, with residual monitoring used as the mechanism to select the appropriate controller. The elemental controllers are each based on an assumed system status: no failures or a single failed surface or sensor. controller selection is evaluated for controller mixing based on all algorithm-computed probabilities of each elemental controller being the 'correct' controller to use. The entire multiple model controller is evaluated against a truth model with a selected failure, and then repeating the process for all failure modes of interest.< >

关键词： Pi control Proportional control Programmable control Adaptive control Actuators Aircraft Aerospace control Condition monitoring control systems Sensor systems

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H∞ identification of stable LSI systems: a scheme with direct application to controller design

H∞ identification of stable LSI systems: a scheme with dire...

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American control Conference (ACC)

作者： A. J. Helmicki C. A. Jacobson C. N. Nett Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY USA Department of Electrical and Computer Engineering Northeastern University Boston MA USA Control Systems Laboratory GE Corporate Research and Development Center Schenectady NY USA

In this paper several techniques are given for the identification of stable LSI discrete time systems from input-output data. Explicit H ∞ norm error bounds are given and convergence in the noise free and the uniformly bounded deterministic noise case are established. The assumptions made on the unknown system are minimal and are limited throughout the paper to a lower bound on the decay rate of the unknown system and an upper bound on the gain of the unknown system. Given this information an experiment and a construction are specified: the experiment involves obtaining a specified number of frequency measurements of the unknown systems at a set of specified frequencies; the construction uses this experimental data to generate an identified model with prescribed H ∞ norm error tolerance to the unknown system. The resulting model identification process is highly efficient from a computational point of view.

关键词： Large scale integration control systems control system synthesis Robust control Research and development Jacobian matrices Error correction Convergence Frequency Taylor series

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Practical Considerations in the Use of Distributed Parameter systems in Modeling: A control Point of View

Practical Considerations in the Use of Distributed Parameter...

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American control Conference (ACC)

作者： A. J. Helmicki C. A. Jacobson C. N. Nett Department of Electrical Computer and Systems Engineering Raneselaer Poytechiic Institute Troy NY USA Department of Electrical and Computer Engineering Northeastern University Boston MA USA Control Systems Laboratory GE Corporate Research and Development Center Schenectady NY USA

This paper is a condensed version of recent work [17] wherein several fundamental practical concerns pertaining to the use of linear, time-invariant, distributed parameter systems as models of physical processes are investigated. In particular, it is argued here that certain common distributed parameter systems exhibit properties which make them unsuitable for use as plant models in the design of feedback compensation. Classes of distributed parameter systems exhibiting these properties are defined and are said to be ill-posed for use in feedback compensator design. The structure of these classes is investigated within an extremely general mathematical framework which imposes no a priori restrictions on the class of distributed parameter systems under consideration. Within this framework necessary and sufficient conditions are given which completely characterise the classes of ill-posed models and establish their equivalence. These conditions are concretely illustrated by way of applications to several well-known flexible structure models. Surprisingly, several of these models are determined to be ill-posed for use in feedback compensator design.

关键词： Distributed parameter systems Feedback control systems Integral equations Distributed computing control system synthesis Jacobian matrices Flexible structures Frequency Linearity

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Nonlinear controller Design for Flight control systems *

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IFAC Proceedings Volumes 1989年第3期22卷 385-390页

作者： J. Hauser S. Sastry G. Meyer Department of Electrical Engineering and Computer Sciences University of California Berkeley CA 94720 USA Flight Control Systems NASA Ames Research Center Moffett Field CA 94305 USA

There has been a great deal of excitement recently over the development of a theory for explicitly linearizing the input-output response of a nonlinear system using state feedback. One shortcoming of this theory is the inability to deal with non-minimum phase nonlinear systems. Highly maneuverable jet aircraft, such as the V/STOL Harrier, belong to an important class of a slightly non-minimum phase nonlinear systems. The non-minimum phase character of these aircraft is clue in part to a slight coupling between rolling moments and lateral accelerations. In this paper, we show that, while straightforward application of the linearization theory to a non-minimum phase system results in a system with a linear input-output response but unstable internal dynamics, designing a feedback control based on a minimum phase approximation to the true system results in a system with desirable properties such as bounded tracking and asymptotic stability.

关键词： Aerospace control nonlinear control systems linearization techniques nonlinear non-minimum phase systems

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The GE MEAD computer-aided control engineering environment

The GE MEAD computer-aided control engineering environment

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IEEE International Symposium on computer Aided control System Design (CACSD)

作者： J.H. Taylor D.K. Frederick C.M. Rimvall H.A. Sutherland Control Systems Laboratories GE Corporate Research and Development Center Schenectady NY USA Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY USA

The GE multidisciplinary expert-aided analysis and design (MEAD) project, which involves the integration of several computer-aided control engineering (CACE) packages under a supervisor which coordinates the execution of these packages with a database manager, an expert system, and an advanced user interface, is discussed. The principal components are, in functional terms: a supervisor, which integrates the underlying CACE packages and coordinates all activity within the GE MEAD computer program (GMCP); an expert system shell and rule bases for expert aiding of specific procedures to relieve the user from unnecessary low-level detail; a database manager for tracking system models that evolve over time along with associated results; and a user interface that facilitates access to the CACE package capabilities by permitting the user to work in several modalities, i.e. menu/forms style, using GE MEAD commands, the core packages' native commands, or the GE MEAD macro facility. The operation of the GMCP, including the user interface, expert system, and database manager, is illustrated by examples.< >

关键词： control engineering computing control engineering Packaging User interfaces Expert systems computer interfaces control systems Data engineering Design engineering engineering management

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Identifying modeling errors in mine electrical power flow input

Identifying modeling errors in mine electrical power flow in...

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Conference Record of the IEEE Industry Applications Society Annual Meeting (IAS)

作者： D.J. Tylavsky L. Gopalakrishnan Department of Electrical & Computer Engineering Arizona State University Tempe AZ USA Systems Control Technology Inc. Palo Alto CA USA

Calculation of voltages in a mine electrical distribution system using a power-flow program may fail to yield meaningful results if the iterative power-flow procedure fails to converge. A modified power-flow technique that converges for most of the mine electrical power-flow input data, even though the same input data do not yield a convergent solution with a traditional Newton power-flow algorithm, is presented. When no operable solution to the power-flow problem exists, the results tend to indicate the location of the modeling error that is responsible for nonconvergence. An extensive case study using data for a mine electrical power system is presented to demonstrate the robustness and error identification properties of the power-flow algorithm.< >

关键词： Load flow Power system modeling Power engineering and energy Data engineering computer errors Voltage Power system analysis computing systems engineering and theory Distributed computing Power engineering computing

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An arm-powered racing bicycle

引用

Assistive Technology 1989年第3期1卷 71-74页

作者： Cooper, Rory A. Institute of Environmental Stress Laboratory and the Control Systems Laboratory Department of Electrical and Computer Engineering University of California Santa Barbara CA United States

A new arm-powered racing bicycle is described. The features and performance of this bicycle are delineated, and the relative advantages over tricycles are outlined. © Taylor & Francis Group, LLC.

关键词： Racing bicycle Recreational equipment Sports

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