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The aim of this paper is to develop efficient online adaptive algorithms for the generalized eigen-decomposition problem which arises in a variety of modern signal processing applications. First, we reinterpret the generalized eigen-decomposition problem as an unconstrained minimization problem by constructing a novel cost function. Second, by applying projection approximation method and recursive least-square (RLS) technique to the cost function, a parallel adaptive algorithm for a basis for the r-dimensional (r > 0) dominant generalized. eigen-subspace and a sequential algorithm based on deflation technique for the first v-dominant generalized eigenvectors are derived. These algorithms can be viewed as counterparts of the extended projection approximation subspace tracking (PAST) and PASTd algorithms, respectively. Furthermore, we modify the parallel algorithm to explicitly estimate the first v-generalized eigenvectors in parallel, not the generalized eigen-subspace. More important, the modified parallel algorithm can be used to extract multiple generalized eigenvectors of two nonstationary sequences, while the proposed sequential algorithm lacks this ability because of slow convergence of minor generalized eigenvectors due to error propagation of the deflation technique. Third, following convergence analysis methods for PAST and PASTd, we prove the asymptotic convergence properties of the proposed algorithms. Finally, computer simulations are performed to investigate the accuracy and the speed advantages of the proposed algorithms. [ABSTRACT FROM AUTHOR]

In this paper, the fundamental characteristics of a novel third-order RF balanced-to-unbalanced filter, namely, a balun filter, for integrated RF module applications are presented. This center-tapped transformer-based new device works concurrently as a balun, an extracted-pole bandpass filter, and a matching network. As coupled resonant tanks are employed to perform the balun type of operation, traditional coupled-resonator filter theory can thus be used to design and analyze such a new device. Moreover, an extracted-pole technique is used not only for creating a transmission zero, but also provides a capability to match the filter with a complex load. In addition to providing a simple design procedure for the device, its working mechanism is also revealed mathematically. Specifically, return-loss sensitivity with respect to each resonator admittance and complex load matching capability are discussed in details. This balun filter has been implemented in a multilayered low-temperature co-fired ceramic substrate, demonstrating its promising potentials in miniaturized RF front-end modules. Experimental measurements are also presented to validate the theory and computer simulations. [ABSTRACT FROM AUTHOR]

This paper investigates quantization methods for feeding back the channel information through a low-rate feedback channel in the context of multiple-input single-output (MISO) systems. We propose a new quantizer design criterion for capacity maximization and develop the corresponding iterative vector quantization (VQ) design algorithm. The criterion is based on maximizing the mean-squared weighted inner product (MSwIP) between the optimum and the quantized beamforming vector. The performance of systems with quantized beamforming is analyzed for the independent fading case. This requires finding the density of the squared inner product between the optimum and the quantized beamforming vector, which is obtained by considering a simple approximation of the quantization cell. The approximate density function is used to lower-bound the capacity loss due to quantization, the outage probability, and the bit error probability. The resulting expressions provide insight into the dependence of the performance of transmit beamforming MISO systems on the number of transmit antennas and feedback rate. Computer simulations support the analytical results and indicate that the lower bounds are quite tight. [ABSTRACT FROM AUTHOR]

Digital microfluidics is the second-generation lab-on-a-chip architecture based upon micromanipulation of droplets via a programmed external electric field by an individually addressable electrode array. Dielectrophoresis (DEP) and electrowetting-on-dielectric (EWOD) are of dominant operating principles. The microfluidic mechanics of manipulating electrified droplets are complex and not entirely understood. This paper presents a numerical simulation method based on droplet electrohydrodynamics. First, a systematic validation study is shown comparing the simulation solution with both analytical and experimental data, quantitatively and qualitatively, and in both steady state and transient time sequences. Such comparison exhibits excellent agreement. Simulations are then used to illustrate its application to computer-aided design of both EWOD-driven and DEP-driven digital microfluidics. [ABSTRACT FROM AUTHOR]

This paper deals with the effect of supply frequency on partial discharge phenomena. Results of measurements performed on artificial and practical test objects are compared with computer simulations based on physical models. This comparative analysis points out and explains the differences in partial discharge phenomena observed in tests performed at different frequencies (from 0.1 to 300 Hz). The consequences associated to the use of different supply frequencies in practical applications are, eventually, outlined. [ABSTRACT FROM AUTHOR]

This paper presents a new three-phase 12/8-pole doubly salient permanent-magnet (DSPM) machine for application to wind power generation. The key is to design and analyze the proposed DSPM generator, namely, the design of a new machine structure to achieve high power density and high robustness and the device of system operation to attain high efficiency. By using finite element analysis, the static characteristics of the proposed generator are given. Hence, the evaluation of system performances is conducted by computer simulation. Experimentation is also given to verify the validity of the proposed DSPM generator. [ABSTRACT FROM AUTHOR]

A magnetically levitated motor (MLM) with two directions of movement is presented in this paper. The thrust and the levitation force of the proposed motor can be achieved simultaneously by using only a single power source. Analytical equations for the operation principle of the proposed MLM are derived. Computer simulations of the MLM characteristics by using the finite-element-analysis method are also presented. The same trend can be found between analytical equations and computer-simulation results. Then, some experimental results are provided to confirm the theoretical analysis. All of the results can provide very useful information of mechanical-structure design and control scheme development for the MLM. [ABSTRACT FROM AUTHOR]

Orthogonal frequency-division multiplexing (OFDM) is an attractive transmission technique for high-bit-rate communication systems. One major drawback of OFDM is the high peak-to-average power ratio (PAPR) of the transmitter's output signal. The selected mapping (SLM) approach provides good performance for PAPR reduction, but it requires a bank of inverse fast Fourier transforms (lFFTs) to generate a set of candidate transmission signals, and this requirement usually results in high computational complexity. In this paper, we propose a kind of low-complexity conversions to replace the IFFT blocks in the conventional. SLM method. Based on the proposed conversions, we develop two novel SLM schemes with much lower complexity than the conventional one; the first method uses only one IFFT block to generate the set of candidate signals, while the second one uses two IFFT blocks. Computer simulation results show that, as compared to the conventional SLM scheme, the first proposed approach has slightly worse PAPR reduction performance and the second proposed one reaches almost the same PAPR reduction performance. [ABSTRACT FROM AUTHOR]

This paper proposes a frame synchronization method for an adaptive array antenna (AAA) used in digital mobile communications. The proposed scheme, which is based on the maxi- mum likelihood estimation (MLE), calculates error signals by subtracting a training sequence convolved with an estimated channel impulse response from the AAA outputs and searches for the timing that minimizes the mean squared errors. Because the proposed scheme can effectively exploit delayed paths of the desired signal, it can improve the synchronization performance on frequency- selective fading channels. Computer simulations show that the proposed scheme can operate properly even in interference-rich fading environments and that it can significantly improve the synchronization performance. [ABSTRACT FROM AUTHOR]

This paper presents a new unsupervised attractor neural network, which, contrary to optimal linear associative memory models, is able to develop nonbipolar attractors as well as bipolar attractors. Moreover, the model is able to develop less spurious attractors and has a better recall performance under random noise than any other Hopfield type neural network. Those performances are obtained by a simple Hebbianlanti-Hebbian online learning rule that directly incorporates feedback from a specific nonlinear transmission rule. Several computer simulations show the model's distinguishing properties. [ABSTRACT FROM AUTHOR]

The problem of blind separation of overdetermined mixtures of sources, that is, with fewer sources than (or as many sources as) sensors, is addressed in this paper. A new method, called Independent Component Analysis using Redundancies in the quadricovariance (ICAR), is proposed in order to process complex data. This method, without any whitening operation, only exploits some redundancies of a particular quadricovariance matrix of the data. Computer simulations demonstrate that ICAR offers in general good results and even outperforms classical methods in several situations: ICAR i) succeeds in separating sources with low signal-to-noise ratios, ii) does not require sources with different second-order or/and first-order spectral densities, iii) is asymptotically not affected by the presence of a Gaussian noise with unknown spatial correlation, iv) is not sensitive to an over estimation of the number of sources. [ABSTRACT FROM AUTHOR]

In this paper we consider the problem of robust radar detection in the presence of Gaussian disturbance with unknown covariance matrix. We design and assess three new robust adaptive detectors, capable of operating in the presence of unknown discrepancies between the nominal and the actual steering vector. Remarkably the new decision rules exhibit a bounded constant false alarm rate (CFAR) behavior and allow, through the regulation of a design parameter, to trade off target sensitivity with sidelobes energy rejection. Finally computer simulations show that the proposed detectors achieve a visible performance improvement, in many situations of practical interest, over the traditional adaptive detection algorithms, especially in the presence of severe steering vector mismatches. [ABSTRACT FROM AUTHOR]

Strong circumstantial evidence suggests that lightning has initiated methane explosions in abandoned and sealed areas of underground coal mines. The Mine Safety and Health Administration (MSHA) investigated several of these occurrences within recent years. The investigated explosions occurred at significant depths, ranging from 700 to 1200 ft. Data from the National Lightning Detection Network indicated a strong correlation between the times and locations of the explosions with those of specific lightning strikes. This paper proposes that corona discharge from a steel borehole casing is the most likely mechanism responsible for these ignitions. A recently investigated mine explosion and fire at a depth greater than 1000 ft was selected for this study. Computer simulations were performed, using data collected at the mine site. CDEGS software from Safe Engineering Services & Technologies, Ltd. and MaxwellSV from Ansoft Corporation were used for the simulations. [ABSTRACT FROM AUTHOR]

Recently, ultra wide-band (UWB) wireless communication technology, which provides high data transmission rates and is capable of linearly trading off between throughput and signal-to-noise ratio (SNR), has drawn much attention for short-range wireless networks. To fully exploit its desirable features and to minimize its interference with coexisting other systems requires knowledge of the SNRs at the receivers. In this paper, we propose an algorithm for estimating the pulse energy-to-noise ratio of an UWB signal through utilization of output samples from a correlator in the receiver and evaluate the performance of the proposed algorithm through computer simulation. A notable feature of the proposed algorithm is that it does not affect the effective throughput because the estimation process does not require any additional specific training signals. [ABSTRACT FROM AUTHOR]

This paper examines the performance of the adaptive array antennas used in digital handset systems by studying the minimum mean square error (MMSE) algorithm at 2 GHz. The array is comprised of multiple quarter-wavelength monopole antennas and planar inverted-F antennas (PIFAs). By calculating the spatial correlation between two different directions, we describe how significant enhancement in the capability of reducing interference signals can be achieved, even when the handset is being held in the vicinity of a human operator in the talking position. Secondly, a computer simulation has been carried out under a flat Rayleigh fading environment with multiple cochannel interference signals, in which the average bit error rate (BER) of the handset adaptive array antenna has been characterized for the coherent detection of phase-shift keyed (PSK) signals. The performance of the handset adaptive array is compared to that of an adaptive array comprising plural parallel half-wavelength dipole antennas that are one half-wavelength apart. The performance was also evaluated with regard to the distance between the handset and the human head for different unequal median values and fading correlations of the received signals. The study has revealed that the adaptive array under consideration has substantial potential, not only to reduce the relative power of interference signals, but also to combat multipath fading of the desired signal by using the spatial diversity function of the MMSE, even in close proximity to a human operator. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to investigate the effect of air-gap position, length, and number on the phenomena preceding flashover along a typical 735-kY porcelain station post insulator unit under heavy ice accretion. Under these conditions, this type of insulator seems to be the most likely subject to flashover. The numerical simulations were performed using Coulomb 3D, a commercial software based on the boundary element method (BEM). Computer simulations were performed during a melting period. Special attention was paid to the presence of a conductive water film at the ice surface and to a partial arc along an air gap. The results obtained showed that the number of air gaps, with or without the presence of a partial arc along them, has a direct effect on the distribution of potential along the iced insulator. Moreover, for the same total arcing distance, the number of air gaps and their position did not affect the average electric field per arcing distance that was used to determine the partial arc presence. Based on these results, suggestions for improving station insulator geometry for icing conditions were proposed. [ABSTRACT FROM AUTHOR]

Selective visual attention in a natural environment can be seen as the interaction between the external visual stimulus and task specific knowledge of the required behavior. This interaction between the bottom-up stimulus and the top-down, task-related knowledge is crucial for what is selected in the space and time within the scene. In this paper, we propose a computational model for selective attention for a visual search task. We go beyond simple saliency-based attention models to model selective attention guided by top-down visual cues, which are dynamically integrated with the bottom-up information. In this way, selection of a location is accomplished by interaction between bottom-up and top-down information. First, the general structure of our model is briefly introduced and followed by a description of the top-down processing of task-relevant cues. This is then followed by a description of the processing of the external images to give three feature maps that are combined to give an overall bottom-up map. Second, the development of the formalism for our novel interactive spiking neural network (ISNN) is given, with the interactive activation rule that calculates the integration map. The learning rule for both bottom-up and top-down weight parameters are given, together with some further analysis of the properties of the resulting ISNN. Third, the model is applied to a face detection task to search for the location of a specific face that is cued. The results show that the trajectories of attention are dramatically changed by interaction of information and variations of cues, giving an appropriate, task-relevant search pattern. Finally, we discuss ways in which these results can be seen as compatible with existing psychological evidence. [ABSTRACT FROM AUTHOR]

The problem of rate detection for a multirate direct sequence/code division multiple access (DS/CDMA) systems is considered in this paper. It is assumed that, in each data-frame, each user may transmit its data at one out of a set of available data-rates, depending, e.g., on the kind of data to be transmitted, on the desired quality-of-service, and on the channel state. Relying on the knowledge of the spreading codes of the user whose rate is to be detected, rate detection algorithms based on the application of the generalized likelihood ratio test are here proposed. Both the cases where either the rates of the interfering users have been already detected and are known to the receiver or these rates are not known to the receiver are separately considered. With regard to the performance assessment, the effectiveness of the proposed rate detection strategies is validated, for a single-path fading channel, through both computer simulations and, with regard to the case that the interfering users rates have already been acquired, through a Chernoff-bounding technique. [ABSTRACT FROM AUTHOR]

In this paper, a new nonlinear companding technique, called "exponential companding", is proposed to reduce the high Peak-to-Average Power Ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) signals. Unlike the *mu;-law companding scheme, which enlarges only small signals so that increases the average power, the schemes based on exponential companding technique adjust both large and small signals and can keep the average power at the same level. By transforming the original OFDM signals into uniformly distributed signals (with a specific degree), the exponential companding schemes can effectively reduce PAPR for different modulation formats and sub-carrier sizes. Moreover, many PAPR reduction schemes, such as μ-law companding scheme, cause spectrum side-lobes generation, but the exponential companding schemes cause less spectrum side-lobes. Computer simulations, which consider a baseband OThM system with Additive White Gaussian Noise (AWGN) channels antI a Solid State Power Amplifier (SSPA), show that the proposed exponential companding schemes can offer better PAPR reduction, Bit Error Rate (BER), and phase error performance than the μ-law companding scheme. [ABSTRACT FROM AUTHOR]

The introduction of multilevel converters makes possible the use of pulse width modulation (PWM) converters and fast switching medium power devices like insulated gate bipolar transistors (IGBTs) for high-voltage, high-power applications, such as flexible ac transmission systems (FACTS). This paper proposes a five-level voltage source inverter (VSI)-chopper for a superconductive magnetic energy storage (SMES) power conditioning system (PCS). The circuit topology and operation principles are presented. The advantages of the proposed power conditioning system have been investigated and compared with present PCS including a traditional transformer coupled multi-pulse VSI-chopper topology. The validity of the system is verified by computer simulation. [ABSTRACT FROM AUTHOR]

This paper introduces an approach for image shadow removal by using pulse coupled neural network (PCNN), based on the phenomena of synchronous pulse bursts in the animal visual cortexes. Two shadow-removing criteria are proposed. These two criteria decide how to choose the optimal parameter (the linking strength 3). The computer simulation results of shadow removal based on PCNN show that if these two criteria are satisfied, shadows are removed completely and the shadow-removed images are almost as the same as the original nonshadowed images. The shadow removal results are independent of changes of intensities of shadows in some range. and variations of the places of shadows. When the first criterion is satisfied, even if the second criterion is not satisfied, as to natural grey images that have abundant grey levels, shadows also can be removed and PCNN shadow-removed images retain the shapes of the objects in original images. These two criteria also can be used for color Images by dividing a color image into three channels (R, G, B). For shadows varying drastically, such as the noisy points in images, these two criteria are still right, but difficult to satisfy. Therefore, this approach can efficiently remove shadows that do not include the random noise. [ABSTRACT FROM AUTHOR]

A new adaptive critic autopilot design for bank-to. turn missiles is presented. In this paper, the architecture of adaptive critic learning scheme contains a fuzzy-basis-function-network based associative search element (ASE), which is employed to approximate nonlinear and complex functions of bank-to-turn missiles, and an adaptive critic element (ACE) generating the reinforcement signal to tune the associative search element. In the design of the adaptive critic autopilot, the control law receives signals from a fixed gain controller, an ASE and an adaptive robust element, which can eliminate approximation errors and disturbances. Traditional adaptive critic reinforcement learning is the problem faced by an agent that must learn behavior through trial-and-error interactions with a dynamic environment, however, the proposed tuning algorithm can significantly shorten the learning time by on-line tuning all parameters of fuzzy basis functions and weights of ASE and ACE. Moreover, the weight updating law derived from the Lyapunov stability theory is capable of guaranteeing both tracking performance and stability. Computer simulation results confirm the effectiveness of the proposed adaptive critic autopilot. [ABSTRACT FROM AUTHOR]

Multioop control strategies have commonly been used to control power inverters of both the voltage-source and current-source topologies for power conversion applications including uninterruptible power supplies and utility interfaces for distributed power generation. However, these control strategies tend to be developed and comparatively evaluated for a particular application, with strategies for other applications presented as independent new developments. This paper presents a generalized analysis of different multiloop control approaches using alternative feedback control variables for several popularly adopted system configurations, highlighting similarities and identifying a generalized optimal control-variable selection criterion that is applicable across most multiloop-controlled inverter systems. The generality of the presented optimal variable selection criterion has been verified through the close similarities between the time-domain waveforms of the different inverter systems simulated in MATLAB Simulink and implemented experimentally in the lab- oratory. [ABSTRACT FROM AUTHOR]

Multicarrier spread spectrum (MC-SS) is an alternative to the conventional spread spectrum (SS) techniques that be- have significantly better when the system is subject to narrow- or partial-band interference. However, successful implementation of the optimum detector requires knowledge of noise and interference variance in each subcarrier band. In this paper, we propose a suboptimal detector for MC-SS that keeps the significant gain of MC-SS over the conventional SS, with a relatively low loss compared with the optimum MC-SS detector. Theoretical analysis and computer simulations that corroborate the theory are presented. [ABSTRACT FROM AUTHOR]

In this paper we present and analyze a new structure for designing a radial basis function neural network (RBFNN). In the training phase, input layer of RBFNN is augmented with desired output vector. Generalization phase involves the following steps: 1) identify the cluster to which a previously unseen input vector belongs; 2) augment the input layer with an average of the targets of the input vectors in the identified cluster; and 3) use the augmented network to estimate the unknown target. It is shown that, under some reasonable assumptions, the generalization error function admits an upper bound in terms of the quantization errors minimized when determining the centers of the proposed method over the training set and the difference between training samples and generalization samples in a deterministic setting. When the difference between the training and generalization samples goes to zero, the upper bound can be made arbitrarily small by increasing the number of hidden neurons. Computer simulations verified the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, the basic bidirectional associative memory (BAM) is extended by choosing weights in the correlation matrix, for a given set of training pairs, which result in a maximum noise tolerance set for BAM. We prove that for a given set of training pairs, the maximum noise tolerance set is the largest, in the sense that this optimized BAM will recall the correct training pair if any input pattern is within the maximum noise tolerance set and at least one pattern outside the maximum noise tolerance set by one Hamming distance will not converge to the correct training pair. This maximum tolerance set is the union of the maximum basins of attraction. A standard genetic algorithm (GA) is used to calculate the weights to maximize the objective function which generates a maximum tolerance set for BAM. Computer simulations are presented to illustrate the error correction and fault tolerance properties of the optimized BAM. [ABSTRACT FROM AUTHOR]

This paper analyzes the feasibility of applying feedback linearization technique to the nonlinear control of susperheater steam pressure and power output of a boiler-tubine generating unit. A nonlinear coordinated controller has been designed and evaluated through computer simulation using a well-established and validated nonlinear boiler-turbine model. The simulation results are presented to illustrate the performance of a nonlinear coordinated control system and compare the proposed strategy with the conventional direct energy balance control strategy. The simulation results show that improvement can be achieved in control with a nonlinear control system. the real benefits obtained include improved dispatch rate, tighter regulation of steam pressure, and reduced maintenance over a wide range of operating conditions, and the improvements in control can be maintained for large changes in operating conditions. [ABSTRACT FROM AUTHOR]

Students typically use small calculators or personal computer applications such as MATLAB or MATHCAD to per- form basic electrical engineering calculations. From the experience of teaching several power engineering courses, the author noted that when using computer software to solve problems, students tend to lose the meaning of the equations, concentrating solely on typing variables and numbers. Some programs are especially inviting for making this error. MATLAB, for instance, does not use any built-in units of measurement, leaving the management of such units to the user. The user's attention shifts from the problem to the units. Although not as powerful and fast as MATLAB, MATHCAD, on the other hand, has a great potential to help students better understand introductory courses. There are two most important features. First, the screen appearance of the equations matches as closely as possible to the traditional form of the equations and helps the students to become familiar with the concepts. Although a bit difficult to type, the equations written in their natural form help avoid errors. A second feature, the use of built-in measurement units, is particularly helpful because the students can concentrate on the meaning of what they learn and know the transformation will be done properly. A technique for representing magnetization curves in MATHCAD (and the corresponding calculations) is also presented. The technique allows for a computer simulation of "graphical calculations" traditionally used in electrical machine design. The class-related experience has shown that even the simple examples presented in this paper could prove to be difficult for students, especially when choosing a programming language to help with the calculations. [ABSTRACT FROM AUTHOR]

Passivity theory is applied to the creation of synthetic, complex multidimensional haptic environments. It can be shown that under appropriate conditions, sufficiently high rendering rates can guarantee the passivity of a simulation produced by a haptic device coupled to a discrete-time realization of a nominally passive environment. The creation of a passive, globally defined, virtual environment is either analytically complex or computationally costly. A method is described whereby a passive environment is created from transitions between locally defined force models that encode static conservative force fields. This is applied to the haptic rendering of tool contact with deformable bodies, in which sparse force-deflection responses are used to define local models. Passivity, continuity, and fidelity are provided by response-function interpolation rather than by interpolation of forces, as in previous methods. The paper also includes an illustrative example. [ABSTRACT FROM AUTHOR]

Many mathematical models have been developed to describe the lateral dynamics of a moving web, including Shelton's model. Experimental results in this study showed that the existing model does not fully describe the characteristic of the lateral dynamics for some typical operating conditions. An experimental model was derived by means of system identification using a well-known least-square method to improve the prediction capability of the lateral dynamics. A commercial guidance system usually has the proportional and integral control structure. Sometimes it may not eliminate the effect of periodic lateral disturbances efficiently which are transferred from upstream spans because the controller relying solely on feedback generates control action only when an output measurement signal differs from a reference value. However, if the disturbance is deterministic, a feed forward control structure may offer simple and effective disturbance rejection performance. In this paper, the lateral position of a web at the upstream span and the identified model of lateral dynamics for the span were used to estimate the effect of disturbance on the lateral dynamics of a moving web at the exit span of the guidance system. A feed forward controller was designed to reject the deterministic disturbance of lateral dynamics of a moving web. The disturbance rejection performance of the proposed controller was verified by computer simulation and experiments. These results showed that the proposed feed forward scheme with an improved mathematical model greatly improved control performance in overcoming the dynamic disturbance. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate the nonasymptotic behavior of the inn likelihood method in the context of lacunar array processing. We derive an analytical expression of the maximum. likelihood mean square error, which is now valid for all signal-to-noise ratio (SNR) ranges. We also provide an analysis of the SNR threshold phenomena, which allows us to derive closed-form formulas for the threshold values. Computer simulations confirm the validity of the theoretical investigations. [ABSTRACT FROM AUTHOR]

Impedance control is one of the most effective methods for controlling the interaction between a manipulator and a task environment. In conventional impedance control methods, however, the manipulator cannot be controlled until the end-effector contacts task environments. A noncontact impedance control method has been proposed to resolve such a problem. This method on only can regulate the end-point Impedance, but also the virtual impedance that works between the manipulator and the environment by using visual Information. This paper proposes a learning method using neural networks to regulate the virtual impedance parameters according to a given task. The validity of the proposed method was verified through computer simulations and experiments with a multi joint robotic manipulator. [ABSTRACT FROM AUTHOR]

This paper describes experiments on the formation and transport, in vacuum and plasma, of a low-energy (70-120 keV), high-intensity (10-30 A/cm²), long-pulse (0.5-1 μs) H+ ion beam. The beam was generated in a magnetically insulated diode with an applied radial B-field and active hydrogen-puff plasma source at the anode. The combination of a ballistic focusing large area anode (250 cm²) with a post-cathode toroidal magnetic tens and straight transport solenoid section provided beam transport to a distance of > 1 m with an overall efficiency of ≥50%. Two-dimensional single-particle computer simulations of the ion's trajectory in the lens/solenoid system supported optimization of the lens and solenoid parameters. [ABSTRACT FROM AUTHOR]

This paper introduces a novel blind equalization algorithm for frequency-selective channels based on a Bayesian formulation of the problem and the sequential importance sampling (SIS) technique. SIS methods rely on building a Monte Carlo (MC) representation of the probability distribution of interest that consists of a set of samples (usually called particles) and associated weights computed recursively in time. We elaborate on this principle to derive blind sequential algorithms that perform maximum a posteriori (MAP) symbol detection without explicit estimation of the channel parameters. In particular, we start with a basic algorithm that only requires the a priori knowledge of the model order of the channel, but we subsequently relax this assumption and investigate novel procedures to handle model order uncertainty as well. The bit error rate (BER) performance of the proposed Bayesian equalizers is evaluated and compared with that of other equalizers through computer simulations. [ABSTRACT FROM AUTHOR]

This paper presents a transformerless ac-dc and or dc-dc converter with a high output voltage multiplicity, which contains only one switch. The converter consists of an inverter and a diode-capacitor multiplier (DCM) and provides a voltage gain equal to double the number of multiplier steps. In the case of ac-dc conversion the proposed converter otters a practically unit power factor and provides a sine wave input current. The analysis of the steady state as well as the transient behavior of the DCM is given and simplified equivalent circuits are proposed. The prototype of the DCM has been built and tested to show the validity of the proposed converter. The theoretical analysis, the computer simulation results, and the experimental testing results are in good agreement. [ABSTRACT FROM AUTHOR]

A novel multi-sensor information fusion methodology for intelligent terrain classification is presented. The focus of this research is to analyze safety characteristics of the terrain using imagery data obtained by on-board sensors during spacecraft descent. This information can be used to enable the spacecraft to land safely on a planetary surface. The focus of our approach is on robust terrain analysis and information fusion in which the terrain is analyzed using multiple sensors and the extracted terrain characteristics are combined to select safe landing sites for touchdown. The novelty of this method is the incorporation of the T-Hazard Map, a multi-valued map representing the risk associated with landing on a planetary surface. The fusion method is explained in detail in this paper and computer simulation results are presented to validate the approach. [ABSTRACT FROM AUTHOR]

In ultrasound elastography, tissue axial strains are calculated from the gradient of the estimated axial displacements. However, the common differentiation operation amplifies the noises in the displacement estimation, especially at high frequencies. In this paper, a low-pass digital differentiator (LPDD) is proposed to calculate the axial strain from the estimated tissue displacement. Several LPDDs that have been well developed in the field of digital signal processing are presented. The corresponding performances are compared qualitatively and quantitatively in computer simulations and in preliminary phantom and in vitro experiments. The results are consistent with the theoretical analysis of the LPDDs. [ABSTRACT FROM AUTHOR]

List mode image reconstruction is attracting renewed attention. It eliminates the storage of empty sinogram bins. Howe ever, a single back projection of all LORs is still necessary for the pre-calculation of a sensitivity image. Since the detection sensitivity is dependent on the object attenuation and detector efficiency, it must be computed for each study. Exact computation of the sensitivity image can be a daunting task for modern scanners with huge numbers of LORs. Thus, some fast approximate calculation may be desirable. In this paper, we analyze the error propagation from the sensitivity image into the reconstructed image. The theoretical analysis is based on the fixed point condition of the list mode reconstruction. The nonnegativity constraint is modeled using the Kuhn-Tucker condition. With certain assumptions and the first order Taylor series approximation, we derive a closed form expression for the error in the reconstructed image as a function of the error in the sensitivity image. The result shows that the error response is frequency-dependent and provides a simple expression for determining the required accuracy of the sensitivity image calculation. Computer simulations show that the theoretical results are in good agreement with the measured results. [ABSTRACT FROM AUTHOR]

The effectiveness of infrared thermography applied to the detection of abandoned land mines is not yet acceptable. It can probably be improved, however, by computerized processing of the thermal images. This requires reference data, which must be provided mainly by experiments. A method is presented here, by which the heating and cooling cycles of a soil with a buried land mine can be replicated with reduced size and duration. The reference data acquired in the laboratory can be associated to realistic on-field tests by simply stretching the space and lime scales. This will permit to reproduce indoors, quickly and effortlessly, the outdoor conditions of any place where the detection of buried land mines must be performed. In this paper, the general thermal problem is described, and the proposed method is comprehensively explained. The results of computer simulations and some laboratory tests are finally reported for validation. [ABSTRACT FROM AUTHOR]

An important macroscopic are parameter, describing its complex nature is the are resistance. It can be easily calculated by using the well-known Warrington formula. Authors investigated the results of Warrington's tests. By taking into account the conditions under which they are obtained (e.g., inaccurate measurement devices), it is unquestionable that these results are today highly empirical and not accurate and general enough. Laboratory testing provided in the high-power test laboratory FGH-Mannheim (Germany), in which long high current arcs are initiated, was the basis for the research results presented in the paper. Based on the analysis of laboratory-recorded arc voltage and current waveforms, the new arc model is derived. An example of arc computer simulation using the new model is given. Based on the new arc model, a new approach to arc resistance calculation is presented. The new formula for arc resistance is compared with the old Warrington formula. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to robust tracking control of the nonlinear sampled systems using a discrete-time fuzzy disturbance observer (DFDO). Novel update and control laws are proposed to guarantee that all the signals in the closed-loop control system are uniformly ultimately bounded (UUB) in a compact set. No persistence of excitation (PE) condition, nor the assumption on the slowness of the change of the fuzzy parameters, Is required. In addition, a robustifying controller is designed to improve the tracking performance. Finally, a computer simulation example Is presented to illustrate the effectiveness and the applicability of the suggested method. [ABSTRACT FROM AUTHOR]

A gyrotron with an axis-encircling electron beam is capable of high-frequency operation, because the high-beam efficiency is kept even at high harmonics of the electron cyclotron frequency. We have designed and constructed such a gyrotron with a permanent magnet. The gyrotron has already operated successfully at the third, fourth, and fifth harmonics. The frequencies are 89.3, 112.7, and 138 GHz, respectively, and the corresponding cavity modes are TE311, TE411, and TE511. The permanent magnet system is quite novel and consists of many magnet elements made of NbFeB and additional coils for controlling the field intensities in the cavity and electron gun regions. The magnetic field in the cavity region can be varied from 0.97 to 1.18 T. At the magnetic field intensities, the output powers at the third and the fourth harmonics are 1.7 and 0.5 kW, respectively. The gyrotron is pulsed, the pulse length is 1 ms and the repetition frequency is 1 Hz. The beam energy is 40 kV and the beam current is 1.2-1.3 A. Beam efficiencies and emission patterns have also been measured. In this paper, the experimental results of the gyrotron are described and compared with computer simulations. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach for navigation of cleaning robots in an unknown workspace. To do so, we propose a new map representation method as well as a complete coverage navigation method. First, we discuss a triangular cell map representation which makes the cleaning robot navigate with a shorter path and increased flexibility than a rectangular cell map representation. Then, we propose the complete coverage navigation and map construction methods which enable the ëleaning robot to navigate the complete workspace without complete information about the environment. Finally, we evaluate the performance of our proposed triangular cell map via the existing distance-transform-based path-planning method comparing it to that of the rectangular cell map. Also, we verify the effectiveness of the proposed methods through computer simulations. [ABSTRACT FROM AUTHOR]

The software simulation as well as the hardware implementation of equalizers for transmissions through nonlinear communication channels based on artificial neural networks structure is presented in this paper. We consider four-quadrature-amplitude-modulation technique as an example and compare the performance of two different structures of equalizer, namely, the linear least-mean-square-based equalizer (LIN) and the functional link artificial neural networks (FLANN). The learning curve and symbol error rate for the two structures are respectively evaluated by computer simulation. Besides, the systems have been implemented using field-programmable-gate-array devices. As FLANN uses functions to expand the dimensionality of the input signals, it has about the same system complexity as LIN. But FLANN can achieve fast processing speed under parallel processing structure. Simulation results have demonstrated that FLANN presents much better error performance than LIN, especially when the communication channel is highly nonlinear. [ABSTRACT FROM AUTHOR]

Independent component analysis is to extract independent signals from their linear mixtures without assuming prior knowledge of their mixing coefficients. As we know, a number of factors are likely to affect separation results in practical applications, such as the number of active sources, the distribution of source signals, and noise. The purpose of this paper to develop a general framework of blind separation from a practical point of view with special emphasis on the activation function adaptation. First, we propose the exponential generative model for probability density functions. A method of constructing an exponential generative model from the activation functions is discussed. Then, a Learning algorithm is derived to update the parameters in the exponential generative model. The learning algorithm for the activation function adaptation is consistent with the one for training the denting model. Stability analysis of the learning algorithm for the activation function is also discussed. Both theoretical analysis and simulations show that the proposed approach is universally convergent regardless of the distributions of sources. Finally, computer simulations are given to demonstrate the effectiveness and validity of the approach. [ABSTRACT FROM AUTHOR]

Conventional fault simulation techniques for field programmable gate arrays (FPGAs) are very complicated and time consuming. The alternative, FPGA fault emulation technique, is incomplete and can be used only after the FPGA chip is manufactured. In this paper, we present efficient algorithms for computing the fault coverage of a given FPGA test configuration. The faults considered are opens and shorts in FPGA interconnects. The presented technique is able to report all detectable and undetectable faults and, compared with conventional methods, is orders of magnitude faster. [ABSTRACT FROM AUTHOR]

In this paper a voltage modulation method based on a triangular carrier wave for the three-phase four-leg voltage source converter is described. The four-leg converter can produce three output voltages independently with one additional leg. The proposed modulation method for the four-leg converter can be implemented with a single carrier by a simple but useful "offset voltage" concept. The method is equivalent to the so called three-dimensional space vector PWM method, but its implementation is much easier. The maximum magnitude of the balanced three-phase voltage and the maximum magnitude of zero sequence voltage, which can be synthesized simultaneously, are derived. The feasibility of the proposed modulation technique is verified by computer simulation and experimental results. These results show that a proposed carrier-based pulse width modulation (PWM) technique can be easily implemented without conventional computational burden. [ABSTRACT FROM AUTHOR]

The condition of rolls has significant influence on the process conditions such as longitudinal tension and lateral error in web transport systems such as in metal and film processes. In particular, a roll-shape defect such as an eccentricity is a major cause for the periodic tension disturbance in the web. In this paper, the authors aim to reject these disturbances caused by unknown shapes of rolls. In order to reject the tension disturbance due to the roll shape, an adaptive eccentricity estimator and eccentricity compensation methods are proposed. The validity of the compensation method including the adaptive eccentricity estimator was tested through computer simulation and experimental study. [ABSTRACT FROM AUTHOR]

Maisie is a C-based discrete-event simulation language that was designed to cleanly separate a simulation model from the underlying algorithm (sequential or parallel) used for the execution of the model. With few modifications, a Maisie program may be executed by using a sequential simulation algorithm, a parallel conservative algorithm or a parallel optimistic algorithm. The language constructs allow the run-time system to implement optimizations that reduce recomputation and state saving overheads for optimistic simulations and synchronization overheads for conservative implementations. This paper presents the Maisie simulation language, describes a set of optimizations, and illustrates the use of the language in the design of efficient parallel simulations. [ABSTRACT FROM AUTHOR]

The paper considers the implementation of distributed discrete event simulation (DDES) using what has been commonly called the Misra approach, after one of the inventors of the approach. A major problem with DDES is that deadlock can occur. Therefore, DDES algorithms must either avoid deadlock in the first place, or detect the existence of deadlock when it does occur and eliminate the deadlock. Misra proposes the use of NULL messages as one way to circumvent the deadlock problem. However, the number of NULL messages can become quite large. Methods are presented for reducing the number of NULL messages through the prediction of channel times. A framework is presented on which the distributed discrete event simulation can be built for applications which can be decomposed into feedforward and feedback networks. [ABSTRACT FROM AUTHOR]