This paper introduces a fuzzy neural based adaptive controller for simultaneous stabilization and robust performance of a family of plants. The family of plants may be attained from linearization of a nonlinear plant ...
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This paper introduces a fuzzy neural based adaptive controller for simultaneous stabilization and robust performance of a family of plants. The family of plants may be attained from linearization of a nonlinear plant around different operating points or large parameter variations in a given plant. The main idea is to design a sequence of controllers corresponding to the different plants utilizing any standard control design. Thereafter, the obtained controllers will form the basis of the knowledge base of a fuzzy controller capable of deriving a desired crisp output through its inference engine. A neural network is utilized to derive a fuzzy model of the plant and to generate the rule base for the fuzzy logic controller through training. The effectiveness of this new scheme is verified on a smart structure with piezoceramic sensors and actuators.
It has been proposed that CDMA systems can be assigned to spectral bands which are presently occupied by narrowband users to further increase spectral capacity. Such CDMA overlay systems could provide new options for ...
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It has been proposed that CDMA systems can be assigned to spectral bands which are presently occupied by narrowband users to further increase spectral capacity. Such CDMA overlay systems could provide new options for efficient utilization of the spectrum with minimal disruption to existing narrowband users, especially if adaptive interference suppression techniques are utilized in the spread spectrum receiver. The bit error rate (BER) performance of the mobile-to-base link of a CDMA system for a single narrowband user which occupies a significant portion of the CDMA bandwidth is considered to evaluate the performance of the adaptive filtering. It is shown that adaptive filtering provides a significant improvement when the CDMA and narrowband powers are of the same order. The dependence of the BER on the filter order, the bandwidth of the interference, and its center frequency relative to the CDMA carrier frequency are demonstrated.< >
The decision feedback equalizer has the advantage of compensating for channel amplitude distortion without enhancing noise. Conventional decision feedback equalizers require a training sequence to help them adapt to u...
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The decision feedback equalizer has the advantage of compensating for channel amplitude distortion without enhancing noise. Conventional decision feedback equalizers require a training sequence to help them adapt to unknown channel characteristics. Training sequences are not always appropriate. In such situations blind equalizers are more suitable. The blind decision feedback equalizer inherits from the conventional the advantage of not enhancing noise, while compensating for severe ISI. It is thus superior over the blind linear equalizer. On the other hand the blind decision feedback equalizer also suffers from error propagation. In this paper we study the transient behavior of the blind DFE. This is done by deriving an upper bound on the probability of error due to residual ISI and show that it vanishes for the noiseless case. We also determine lower and upper bounds on the probability of error for the additive white Gaussian noise case. The upper bound obtained is the same as that of Duttweiler, et al. (1974). Using a different approach from that of Duttweiler, et al., we derive a lower bound. This bound is tighter than tile "no ISI" lower bound.< >
This paper presents an investigation of the misconvergence of the constant modulus algorithm (CMA) for blind equalization in the reception of M-ary PSK or QAM signals that are derived from encoding binary PN sequences...
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This paper presents an investigation of the misconvergence of the constant modulus algorithm (CMA) for blind equalization in the reception of M-ary PSK or QAM signals that are derived from encoding binary PN sequences. Formulas for the period and probability density-function (p.d.f.) of the pseudo-random M-ary sequence as functions of M and the period of the underlying binary PN sequence are given. The distortion of the probabilistic symmetry of the transmitted constellation is also quantified. Simulation results are presented that illustrate the influence of these signal characteristics on the convergence behavior of CMA.< >
This paper presents a method for automatic detection of targets with nonlinear motion embedded in dynamic clutter. This is achieved via processing the targets' incoherent ISAR data that are less vulnerable to mult...
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This paper presents a method for automatic detection of targets with nonlinear motion embedded in dynamic clutter. This is achieved via processing the targets' incoherent ISAR data that are less vulnerable to multiplicative noise (phase errors). It is shown that the incoherent ISAR signature of a target scene may be viewed as its baseband ISAR signature. Thus, the magnitude of an ISAR database that is severely contaminated with phase errors, i.e., incoherent ISAR data, may be used for ISAR detection of moving targets. Incoherent ISAR data in the fast-time and slow-time domain are transformed into another two-dimensional domain. The signature of a target in the transformed domain is shown to be localized based on its mid-point range and speed. This localized statistic is suitable for automatic, i.e., machine-based, detection of stationary as well as moving targets in the scene.< >
Microwave characteristics are reported for n- and p- MOS transistors fabricated with thin-film Silicon-on-Sapphire technology. The gates were defined with I-line optical lithography, and ranged down to 0.5 /spl mu/m (...
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Microwave characteristics are reported for n- and p- MOS transistors fabricated with thin-film Silicon-on-Sapphire technology. The gates were defined with I-line optical lithography, and ranged down to 0.5 /spl mu/m (drawn dimension). The f/sub t/ values of the transistors reach 22 GHz for the n-channel structures and 21 GHz for the p-channel devices. The PMOS results are significantly higher than found with other Si or III-V technologies, and can potentially lead to high performance complementary microwave circuits. Small signal transistor models are similar to the ones for GaAs FETs. Dependence of model parameters on gate length were determined.< >
In this paper, we present a semi-automatic technique to quantize and to visualize myocardial perfusion defects volumetrically. This involves: (1) differentiating the myocardium from encroaching viscera, (2) determinin...
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This paper discusses the compliance control of an ultrasonic motor powered prosthetic forearm which utilizes cutaneously measured electromyogram (EMG) signals sensed with the electrodes over the muscles as means of de...
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This paper discusses the compliance control of an ultrasonic motor powered prosthetic forearm which utilizes cutaneously measured electromyogram (EMG) signals sensed with the electrodes over the muscles as means of detecting motor commands sent by the central nervous system (CNS). Compliance control of the artificial limb was studied by implementing the bilinear model of the forearm and hand. This model emphasizes the role of the visco-elastic properties of the musculo-skeletal system of the actual limb in controlling its net configuration and movement. The flexor and extensor muscles extending over a joint influence the total joint impedance and determine the equilibrium position of the joint. Relaxing both flexor and extensor muscles makes the joint compliant to external forces, while activating both muscles increases the impedance of the joint.< >
This paper presents an adaptive control scheme based on a fuzzy logic algorithm and its application to end-effector positioning of flexible-link manipulators. Here, a fuzzy based adaptive controller is considered due ...
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This paper presents an adaptive control scheme based on a fuzzy logic algorithm and its application to end-effector positioning of flexible-link manipulators. Here, a fuzzy based adaptive controller is considered due to its simplicity and the fact that it does not require expressing the controller in terms of the system parameters, as it is necessary in the case of self-tuning regulators. This controller is based on a functional fuzzy model where the consequents are crisp functions represent controllers designed for different operating regimes. The premise is constituted by the fuzzy subsets corresponding to the process parameters estimated in real time. The effectiveness of this new scheme is verified on a clamped free beam and a single-line flexible arm instrumented with piezoceramic sensors and actuators. It is shown that robust performance may be achieved in face of large parameter variations.< >
This paper studies the ability of the exponentially weighted RLS algorithm to track a Doppler shifted BPSK communications signal. This is modeled as a chirped AR1 process in Gaussian white noise. Expressions for the o...
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This paper studies the ability of the exponentially weighted RLS algorithm to track a Doppler shifted BPSK communications signal. This is modeled as a chirped AR1 process in Gaussian white noise. Expressions for the optimum Wiener filter, noise misadjustment, and lag misadjustment are shown. It is shown that as in the chirped sinusoid case the error can be written in terms of the forgetting rate /spl beta/=1-/spl lambda/ of the RLS algorithm; the noise misadjustment is of the order /spl beta/ and lag misadjustment of order 1//spl beta//sup 2/. However, as the bandwidth of the signal increases the relative lag misadjustment is shown to decrease.< >
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