nils-herrmann/clean_scirepeval huggingface dataset:
SAR image despeckling using vector-based hidden Markov model in wavelet domain

Despecking is an essential part of any synthetic aperture radar (SAR) imagery systems. In this work, we propose a new despeckling method for SAR images in the wavelet domain. The performance of a method can be significantly improved by taking into account the statistical dependencies between the wavelet coefficients. It has been shown that the vector-based hidden Markov model (HMM) is capable of capturing the subband marginal distribution and the inter-scale and cross orientation dependencies of the wavelet coefficients. In view of this, in order to estimate a speckle-free SAR image, the Bayesian maximum a posteriori estimator using the vector-based HMM as a prior for the wavelet coefficients of images is developed by using the real and synthetically-speckled SAR images. The performance of the proposed despeckling method is evaluated and shown to be superior to some of the existing techniques in terms of providing better preservation of the details and yielding better visual quality.
PLL based discrete time varying filter for estimation of parameters of a sine signal corrupted by a closely spaced FM interference

A method for the estimation of the parameters of a sine signal corrupted by a strong FM interference is presented. The method consists of two stages. In the first stage, an FM interference is transformed into a harmonic wave with known frequency by using a special time-warping technique. This harmonic interference is then rejected in the transformed time domain by a time-invariant constrained notch filter. The time-warping is implemented using nonuniform sampling obtained by utilizing a phase locked loop (PLL) technique. It is shown that such processing results in a 0-dB signal-to-interference ratio at the output independently of the signal-to-interference ratio at the input (for negative values in decibels). The second stage involves parameter estimation, where a constrained adaptive notch filter is used for the enhancement of a signal under analysis.<<ETX>>
Score reliability based weighting technique for score-level fusion in multi-biometric systems

The performance of multiple matchers heavily influence the recognition accuracy of a multi-biometric system under the simple sum-rule-based score-level fusion. In this paper, a weighting technique, referred to as score reliability based weighting (SRBW) technique, is developed to estimate weights for the matchers in order to improve the recognition rate of multi-biometric systems at the score level. In the proposed technique, the reliabilities are computed directly from the raw matching scores obtained from the individual matchers. The proposed weighting technique does not require a priori knowledge of the rankings of matching scores, or the equal error rates, or the genuine/impostor score distributions of the individual matchers used in the system. The experimental results show that the performance of a multi-biometric system using the proposed weighting technique is superior to that of the uni-biometric systems or to that of the multi-biometric systems using the existing weighting techniques in terms of equal error rate and genuine acceptance rate at 1% false acceptance rate.
A General Class of Split-Radix FFT Algorithms for the Computation of the DFT of Length-$2^{m}$

In this paper, a general class of split-radix fast Fourier transform (FFT) algorithms for computing the length-2m DFT is proposed by introducing a new recursive approach coupled with an efficient method for combining the twiddle factors. This enables the development of higher split-radix FFT algorithms from lower split-radix FFT algorithms without any increase in the arithmetic complexity. Specifically, an arbitrary radix-2/2s FFT algorithm for any value of s, 4les sles m, is proposed and its arithmetic complexity analyzed. It is shown that the number of arithmetic operations (multiplications plus additions) required by the proposed radix-2/2s FFT algorithm is independent of s and is (2m-3)2m+1+8 regardless of whether a complex multiplication is carried out using four multiplications and two additions or three multiplications and three additions. This paper thus provides a variety of choices and ways for computing the length-2m DFT with the same arithmetic complexity.
Design of arbitrary-order minimal operational-amplifier BIBO stable Bode-type variable-amplitude active-RC equalizers

This paper presents a new technique for the exact design and minimal operational-amplifier realization of arbitrary-order bounded-input-bounded-output (BIBO) stable Bode-type variable-amplitude (VA) active-RC equalizers. This technique is based on the realization of the VA equalizer transfer function directly as the voltage transfer function from port 1 to port 2 of an active-R three-port network when its port 3 is terminated in the active-RC realization of the corresponding (positive-real) shaping impedance function. The salient feature of the resulting VA active-RC equalizers is that they permit the continuous variation of the equalizer transfer function from the corresponding shaping transfer function to its inverse through the use of one single (positive) variable resistor only. In addition, they permit arithmetically symmetric changes in the logarithmic magnitude-frequency response of the equalizer through geometrically symmetric changes in the value of the constituent variable resistor. An application example is given to illustrate the main results.
Morphology-Based Automatic Seizure Detector for Intracerebral EEG Recordings

In this paper, a new seizure detection system aimed at assisting in a rapid review of prolonged intracerebral EEG recordings is described. It is based on quantifying the sharpness of the waveform, one of the most important electrographic EEG features utilized by experts for an accurate and reliable identification of a seizure. The waveform morphology is characterized by a measure of sharpness as defined by the slope of the half-waves. A train of abnormally sharp waves resulting from subsequent filtering are used to identify seizures. The method was optimized using 145 h of single-channel depth EEG from seven patients, and tested on another 158 h of single-channel depth EEG from another seven patients. Additionally, 725 h of depth EEG from 21 patients was utilized to assess the system performance in a multichannel configuration. Single-channel test data resulted in a sensitivity of 87% and a specificity of 71%. The multichannel test data reported a sensitivity of 81% and a specificity of 58.9%. The new system detected a wide range of seizure patterns that included rhythmic and nonrhythmic seizures of varying length, including those missed by the experts. We also compare the proposed system with a popular commercial system.
Spectral Efficiency Maximization of Multiuser Massive MIMO Systems With Finite-Dimensional Channel via Control of Users’ Power

This brief investigates the spectral efficiency of multiuser massive multiple-input multiple-output systems with a very large number of antennas at a base station serving single-antenna users. A practical physical channel model is proposed by dividing the angular domain into a finite number of distinct directions. A lower bound on the achievable rate of uplink data transmission is derived using a linear detector for each user and employed in defining the spectral efficiency. The obtained lower bound is further modified for the maximum-ratio combining and zero-forcing receivers. A power control scheme based on the large-scale fading is also proposed to maximize the spectral efficiency under peak power constraint. Experiments are conducted to evaluate the obtained lower bounds and the performance of the proposed method. The numerical results show a comparison between the performances of both receivers along with the advantage of the proposed power control scheme in terms of the spectral efficiency.
Geometric and shading correction for images of printed materials: a unified approach using boundary

We present a novel approach that uses boundary interpolation to correct (1) geometric distortion and (2) shading artifacts present in images of printed materials. Unlike existing approaches, our algorithm can simultaneously correct a variety of geometric distortions, including skew, fold distortion, binder curl, and combinations of these. In addition, the same interpolation framework can estimate the intrinsic illumination component of the distorted image to correct shading artifacts.
Bispectrum based mixed phased item identification by AR/ARMA models: a group delay approach

A method of identification of a mixed phase system from its output by an AR/ARMA model is proposed. This is achieved by relating the bispectrum phase and magnitude to the system group delay function (GDF). The maximum and the minimum phase decomposition properties of the GDFs allow the identification by the AR model. In addition, the pole-zero decomposition property leads to identification by the ARMA model. The proposed method uses only the bispectrum information, and it is applicable to MA, AR, or ARMA systems with mixed phase zeros, mixed phase poles, or both.
Joint Space-Time Parameter Estimation for Underwater Communication Channels with Velocity Vector Sensor Arrays

In this paper, the problem of joint space-time parameter estimation for underwater wireless communication channels in a multipath environment is addressed. We consider the receive antenna array to be configured with multiple vector sensors, each of which consists of a pair of orthogonal velocity sensors. A quadrilinear model for the channel is formulated, and a quadrilinear decomposition method developed for joint angle and delay estimation (JADE). In addition, a computationally simple subspace-based algorithm is proposed for the problem under consideration. The basic idea behind this algorithm is to use the angle information embedded in the velocity vector sensors to start two polynomial rooting procedures for the angle and delay in succession. Simulation results are finally presented to verify the efficacy of the proposed algorithms.
Realization of (g/sub m/-C) current mode filters from associated (g/sub m/-C) voltage mode filters

Most of the work done in the last decade on current-mode (CM) filters has been based on designing a CM filter from a voltage-mode (VM) filter that uses voltage amplifiers. It is shown in this paper that by using the concept of network transposition, introduced in 1971, by Bhattacharyya and Swamy that a VM filter built with an operational transconductance amplifier (OTA), i.e., a g/sub m/-C VM filter, can be easily transformed into a g/sub m/-C CM filter using the same OTA as the active device.
Contourlet domain image denoising using the alpha-stable distribution

In this paper, a new contourlet-based method for denoising of images corrupted by additive white Gaussian noise is proposed. The alpha-stable distribution is used to model the contourlet coefficients of noise-free images. This model is then exploited to develop a Bayesian minimum mean absolute error estimator. A modified empirical characteristic function-based method is employed for estimating the parameters of the assumed alpha-stable prior. The performance of the proposed denoising method is evaluated by using standard noise-free images corrupted with simulated noise and compared with that of the other state-of-the-art methods. The results show that the proposed method provides values of the peak signal-to-noise ratio higher than that provided by some of the existing techniques along with superior visual quality images.
Cryptographic applications of Brahmagupta-Bha/spl tilde/skara equation

The Brahmagupta-Bha/spl tilde/skara (BB) equation is a quadratic Diophantine equation of the form NX/sup 2/+k=Y/sup 2/, where k is an integer (positive or negative) and N is a positive integer such that /spl radic/N is irrational. A particular case of the BB equation with k=1 is also known as Pell equation in literature. This equation in the Galois Field GF(p), where p is an odd prime has some practically useful properties. Application of these properties in two different fields of cryptography, namely, digital encryption and user authentication are discussed in this paper. For those applications, where software computation of the roots of the BB equation is unacceptable for being too slow, a hardware architecture for using the BB equation in GF(p) is given that is useful for implementation in VLSI form.
Spatially Adaptive Wavelet-Based Method Using the Cauchy Prior for Denoising the SAR Images

The speckle noise complicates the human and automatic interpretation of synthetic aperture radar (SAR) images. Thus, the reduction of speckle is critical in various SAR image processing tasks. In this paper, we introduce a new spatially adaptive wavelet-based Bayesian method for despeckling the SAR images. The wavelet coefficients of the logarithmically transformed reflectance and speckle noise are modeled using the zero-location Cauchy and zero-mean Gaussian distributions, respectively. These prior distributions are then exploited to develop a Bayesian minimum mean absolute error estimator as well as a maximum a posteriori estimator. A new context-based technique with a reduced complexity is proposed for incorporating the spatial dependency of the wavelet coefficients with the Bayesian estimation processes. Experiments are carried out using typical noise-free images corrupted with simulated speckle noise as well as real SAR images, and the results show that the proposed method performs favorably in comparison to some of the existing methods in terms of the peak signal-to-noise ratio, speckle statistics and structural similarity index, and in its ability to suppress the speckle in the homogeneous regions
New radix-(2/spl times/2/spl times/2)/(4/spl times/4/spl times/4) and radix-(2/spl times/2/spl times/2)/(8/spl times/8/spl times/8) DIF FFT algorithms for 3-D DFT

In this paper, new three-dimensional (3-D) radix-(2/spl times/2/spl times/2)/(4/spl times/4/spl times/4) and radix-(2/spl times/2/spl times/2)/(8/spl times/8/spl times/8) decimation-in-frequency (DIF) fast Fourier transform (FFT) algorithms are developed and their implementation schemes discussed. The algorithms are developed by introducing the radix-2/4 and radix-2/8 approaches in the computation of the 3-D DFT using the Kronecker product and appropriate index mappings. The butterflies of the proposed algorithms are characterized by simple closed-form expressions facilitating easy software or hardware implementations of the algorithms. Comparisons between the proposed algorithms and the existing 3-D radix-(2/spl times/2/spl times/2) FFT algorithm are carried out showing that significant savings in terms of the number of arithmetic operations, data transfers, and twiddle factor evaluations or accesses to the lookup table can be achieved using the radix-(2/spl times/2/spl times/2)/(4/spl times/4/spl times/4) DIF FFT algorithm over the radix-(2/spl times/2/spl times/2) FFT algorithm. It is also established that further savings can be achieved by using the radix-(2/spl times/2/spl times/2)/(8/spl times/8/spl times/8) DIF FFT algorithm.
Design of OTA-C oscillator and current-mode filters using network trasportation

OTA-C filters have received a lot of attention. for high frequency continuous-time applications. The design of OTA-C filters has traditionally been considered voltage mode signal processing. Over the last decade, current mode signal processing has emerged as an important class of analogue circuitry because of the simplicity associated with implementing basic operations such as signal summing and replication, and the potential to operate at higher signal bandwidths and lower voltage than in the voltage mode approach. A number of researchers have investigated as to how to design current mode filters. For instance, Sun and Fidler have proposed current-mode two-integratorloop dual-output OTA-C filters and current-mode multiple-loop feedback filters. In principle, various current-mode filter structures can be generated by these systematic methods. However, complicated voltage/current calculation is needed for loop analysis or approaches requiring solution of nonlinear equations are required to solve coeficient matching equations associated with the feedback matrix. However, the principle of network transposition, proposed by Bhattacharyya and Swamy as early as 1971, can be used to advantage to derive, in a straightforward manner, current-mode OTA-C filter structures fiom well-known OTA-C voltage-made filter structures. Application of network transposition is extended to oscillators, and several new oscillator circuits derived from existing oscillator circuits are given. Furthermore, it is shown that the application of network transposition to differential-input, differential-output networks leads to the realization of fully differential current mode filters and oscillators. As illustrations, several new current-mode fully differential OTA-C filters and oscillators are derived using network transposition. Experimental results on several voltage-mode and current-mode filters and oscillators, built using commercial OTA (LMI 13700) devices, capacitors and resistors will be presented.
An efficient simulated annealing algorithm for graph bisectioning

A new simulated annealing algorithm for solving the graph bisectioning problem is proposed. The authors run their simulated annealing algorithm, the Kernighan-Lin algorithm, and the Saab-Rao algorithms on the same set of random graphs with 50 to 500 nodes and compare their performances. Experiments show that their simulated annealing algorithm provides lower bisection cost than the Kernighan-Lin algorithm and the Saab-Rao algorithms for all of the graphs and their algorithm takes less running time than the other algorithms mentioned for all of the graphs with more than 100 nodes. For the simulated annealing approach, they conclude that sequential neighborhood search outperforms random neighborhood search in solving the graph bisectioning problem.<<ETX>>
Low power FIR filter FPGA implementation based on distributed arithmetic and residue number system

In this paper, several low power techniques are proposed for the FPGA implementation of a distributed arithmetic and residue number system-based FIR filter. Two algorithms are proposed to reduce the size of the residue-to-binary converter, which is the crucial part of the system. The area, speed and power consumption of the filter is improved accordingly. Furthermore, a lookup table (LUT) partition technique is presented such that the most frequently accessed locations are stored in a smaller memory. The power consumption of the LUTs is reduced because accesses to smaller LUTs dissipate less power. The implementation results show a 20% power reduction by using the proposed methods.
New approach for suppression of FM jamming in GPS receivers

A new approach is proposed for the suppression of FM jammers in C/A code GPS receivers. This approach is based on the cascading of the augmented-state approximate conditional mean (ASACM) filter and the discrete wavelet transform (DWT) filter. An ASACM filter for single interference suppression in spread-spectrum systems has been reported in the recent literature. However, the formulation of the ASACM filter and its performance analysis is lacking in the case of suppression of multiple FM interferences. The ASACM filter is formulated here for the suppression of multiple FM jammers. Further, a DWT filter using biorthogonal wavelet is suggested for the suppression of FM jammers. Finally, these two filters are cascaded to get an optimum performance for higher jammer to signal ratio, which is of importance in the GPS, for the case of suppression of multiple FM jammers. The performance of the proposed filters is analyzed through simulation examples for the suppression of single and multiple FM jammers in GPS receivers
An area-time-efficient residue-to-binary converter

In this paper, a new residue-to-binary conversion algorithm, that reduces the size of modulo operation required by the Chinese remainder theorem, is introduced. Based on this algorithm, an efficient residue-to-binary converter is proposed for a general residue number system. The proposed converter achieves a significantly better performance in terms of area, time, and power consumption than existing devices. For the case of the 28-bit dynamic range, the proposed converter is about 20% faster while requiring only 70% of the area, compared to the best existing converter (Srikanthan et al, IEE  1998). Also, the power consumption is reduced by 16% in high speed situations and 50% in low voltage situations.
Performance analysis of a MIMO scheme for watermarked medical images transmission over Rayleigh fading channels

Digital watermarking is a technique adapted to embed patient information as watermark with medical images to reduce storage and transmission overheads. A multiple-input multiple-output (MIMO) transmission scheme in which multiple antennas are used in both transmitter and receiver has emerged as one of the most significant technical breakthroughs in modern wireless communications. This paper presents a scheme with a MIMO channel for transmission of watermarked medical images over Rayleigh fading channels and its performance is analyzed using MIMO ML detector at the receiver.
Ill condition identification for linear prediction-based MIMO-OFDM channel estimation

Based on our previously developed signal perturbation free (SPF) transmit scheme, a new linear prediction (LP)-based channel estimation algorithm with ill condition identification is proposed for MIMO-OFDM systems. Based on the estimated correlation matrix of the received signal without signal perturbation error by employing the SPF transmit scheme, a SPF LP-based MIMO-OFDM channel estimation algorithm is developed. In this algorithm, the common ill-conditioning problem existing in most LP-based blind methods is properly solved based on two ill-condition test rules. Computer simulations show that the proposed SPF LP-based channel estimation algorithm significantly outperforms the same algorithm without ill condition identification, the nulling-based semi-blind method as well as the LS method.
Statistically optimal null filters for processing short record length signals

In this paper, we propose an alternate non-parametric statistically optimal method of null filtering. One of the important features of this method lies in its ability to process signals of short record lengths. The optimality criteria for maximum output SNR and the minimum mean-square error are combined to generate the new approach. The method is first designed for the coherent case (where the desired signal shape is a priori known) and later extended to include the non-coherent case based on orthogonal signal expansion. To deal with a non-orthogonal signal expansion, we propose a sliding Gram-Schmidt orthogonalization. An application to separate two closely spaced damped sinusoids is considered. Simulation results are presented comparing the proposed methods with the conventional one based on Constrained Notch Filtering.