作者：
Arvanitis, KGResearch Assistant
Division of Computer Science Department of Electrical and Computer Engineering National Technical University of Athens Athens Greece
In this paper, the certainty equivalence principle is used to combine a discrete-time adaptive law with a control structure derived from the linear-quadratic regulation problem. The proposed control structure is mainl...
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In this paper, the certainty equivalence principle is used to combine a discrete-time adaptive law with a control structure derived from the linear-quadratic regulation problem. The proposed control structure is mainly based on multirate sampling of the output of the continuous-time plant under control and allows us to regulate the sampled closed-loop system, subject to a quadratic performance criterion, without making assumptions on the plant other than controllability and observability and the knowledge of two sets of structural indices. Using the proposed algorithm, the adaptive regulation problem is reduced to the determination of a fictitious static state feedback controller. Known techniques usually resort to the computation of full-order adaptive state observers, thus introducing high-order exogenous dynamics in the control loop. Moreover, persistence of excitation and parameter convergence of the plant are provided without making any additional assumption on the system, as compared to known adaptive linear-quadratic regulation schemes.
The kinematics of rolling contact are derived for two surfaces of arbitrary shape rolling on each other. The kinematic equations are applied to a multifingered hand manipulating some object of arbitrary shape in three...
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The kinematics of rolling contact are derived for two surfaces of arbitrary shape rolling on each other. The kinematic equations are applied to a multifingered hand manipulating some object of arbitrary shape in three dimensions, and a scheme is presented for the control of such a hand which is a generalization of the computed torque method of control of robot manipulators. In implementing the control, it is required that all applied forces lie within the friction cone of the object so that sliding does not occur. The theory has been validated by dynamic graphical simulations of the resulting closed-loop system for several examples.< >
The author demonstrates how generalized cyclic codes, defined over the rings and fields usually used in high-speed convolution of discrete-time sequence processing, can be incorporated directly and quite naturally wit...
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The author demonstrates how generalized cyclic codes, defined over the rings and fields usually used in high-speed convolution of discrete-time sequence processing, can be incorporated directly and quite naturally within the data processing of such arithmetic systems. Design methods for one class of real cyclic codes are detailed, along with examples. Encoding and parity manipulation methods are developed which permit straightforward and efficient mechanizations. Errors are detected immediately at the conclusion of the processing pass, allowing appropriate error control actions to be initiated. Typical responses to detected errors may be to retry the calculation, reconfigure the overall system, or enter a subsystem testing mode. A complexity analysis of the protection subsystems shows that protection requires additional arithmetic complexity on the order of the number of parity positions squared.
A theory based on the Kukhtarev-Vinetskii model is developed that provides the evolution equation of one-dimensional optical spatial solitons in photorefractive media. In the steady-state regime and under appropriate ...
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A theory based on the Kukhtarev-Vinetskii model is developed that provides the evolution equation of one-dimensional optical spatial solitons in photorefractive media. In the steady-state regime and under appropriate external bias conditions, our analysis indicates that the underlying wave equation can exhibit bright and dark as well as gray spatial soliton states. The characteristics of these self-trapped optical beams are discussed in detail. (C) 1995 Optical Society of America
Presented is a two-parameter model of line loss in which the frequency dependence of loss is determined by way of the loss at the selected frequency and the conductor diameter. The model quite faithfully represents th...
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Presented is a two-parameter model of line loss in which the frequency dependence of loss is determined by way of the loss at the selected frequency and the conductor diameter. The model quite faithfully represents the actual loss of the line, and is much better than the often used square-root f model.
A three-layered neural network to perform the well-known Huffman-Clowes scene labeling that is a typical constraint satisfaction problem in artificial intelligence is proposed. The proposed constraint propagation neur...
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A three-layered neural network to perform the well-known Huffman-Clowes scene labeling that is a typical constraint satisfaction problem in artificial intelligence is proposed. The proposed constraint propagation neural network uses the topology and the interconnections of neurons to achieve global consistency through propagating local constraints. Given a line drawing, the proposed neural network establishes a consistent labeling for all the edges or detects an inconsistency. The structure of this neural network consists of three layers: the edge, the vertex, and the junction type layers. The first layer of this network contains the initial or final decisions about the junction labels associated with the vertices. Since each edge is shared by two junctions, it is represented by two vectors (one for each junction) and connects with the vertex of the junction represented by a neuron in the second layer. Once one of these two edge vectors is labeled, the information is propagated to the other edge vector representing the same edge in the input line drawing. In the second layer, each neuron represents a vertex in the input line drawing and sums up the weighted signals from the first layer. Then, there is a competition among the neurons and only one neuron is selected (based on the magnitude of its incoming signals) as the winner to fire. This winner becomes the candidate to be labeled next. The output of the winner is not only forwarded to the third layer for deciding which valid junction type it belongs to but also fed back to the first layer for updating its edges. The neurons in the third layer receive the signals sent by the winner in the second layer and the information about the edges associated with this winner. There are 18 neurons in the third layer representing the 18 junction types. The connections between this layer and the first layer encode the labels of the edges of the junction types. Once the junction type is determined, the representing neuron (in the
A class of discrete-event models called finitely recursive processes (FRP) is introduced. These models are motivated by problems in supervisory control, while some of the formal structure is based on C.A.R. Hoare'...
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A class of discrete-event models called finitely recursive processes (FRP) is introduced. These models are motivated by problems in supervisory control, while some of the formal structure is based on C.A.R. Hoare's (1985) communicating sequential processes. Although only preliminary work is presented, it is believed that for many problems it offers a formalism that is superior to that of finite-state machines recently introduced in control theory. Simple examples illustrate the calculus of operators for FRPs. A more complex exercise is worked out to show how the formalism is used to construct a scheme for handling connections in a data network. This preliminary work needs to be extended in several directions, especially in directions that can assist implementation of real controllers based on the FRP formalism. Some specific suggestions towards this end are made.< >
作者：
BAHL, SRDELALAMO, JAIEEE
Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology
In0.52Al0.48As/n+-In0.53Ga0.47As HFET's have been fabricated with different channel thicknesses. We show that by reducing the channel thickness from 350 to 100 angstrom the reverse gate breakdown voltage improves ...
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In0.52Al0.48As/n+-In0.53Ga0.47As HFET's have been fabricated with different channel thicknesses. We show that by reducing the channel thickness from 350 to 100 angstrom the reverse gate breakdown voltage improves from 9 to 19 V. We partially attribute this to the increased effective bandgap that results from energy quantization in the channel. This bandgap enhancement is directly confirmed by photoluminescence (PL) measurements on the same heterostructures. Channel quantization emerges as a promising approach for exploiting the excellent transport properties of InGaAs with high InAs mole fraction. The principle behind our work should be applicable to other narrow-gap semiconductors.
A systematic procedure is presented for designing a knowledge base which exactly implements a specified bounded separable function in fuzzy logic. The design of an fuzzy logic control (FLC) for local linear control is...
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A systematic procedure is presented for designing a knowledge base which exactly implements a specified bounded separable function in fuzzy logic. The design of an fuzzy logic control (FLC) for local linear control is a special case of the result. Examples, including controller design for a nonlinear process control application, are presented.
The effect of optical feedback on the stability of the modelocking frequency of monolithic, passively modelocked semiconductor lasers at similar to 50 GHz is investigated. Optical feedback leads to linewidth narrowing...
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The effect of optical feedback on the stability of the modelocking frequency of monolithic, passively modelocked semiconductor lasers at similar to 50 GHz is investigated. Optical feedback leads to linewidth narrowing, frequency pulling, and multiple modes of the intensity modulations in modelocked lasers, reminiscent of similar effects on the optical frequency in conventional continuous wave (CW) lasers. The narrowest observed line had a full-width-at-half-maximum (FWHM) of 56 kHz, which represents close to two orders of magnitude reduction of the linewidth compared to the situation without feedback. The effects of the optical feedback vary periodically as the length of the feedback delay is varied, with a periodicity that roughly matches the ''modelocking wavelength.'' This wavelength is on the order of millimeters, which makes the mechanical stability of the optical feedback loop relatively uncritical.
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