nils-herrmann/clean_scirepeval huggingface dataset:
Phase estimation by bispectrum: a group delay approach

A method of extracting the system phase from the bispectrum phase, based on a group delay approach, is proposed. The system phase estimation is achieved by relating the bispectral phase to the system group delay function. The proposed method has certain advantages over some of the existing methods. It is applicable for moving average (MA) or autoregressive (AR) or ARMA systems. Even with a few triple correlation lags, its performance is either superior to or at par with those obtained by Lii and Rosenblatt's method or Brillinger's method. The method has been evaluated for ARMA systems.<<ETX>>
Design of Mth-band filters for image interpolation application

In this paper, a generalized polyphase (GP) structure based design method for Mth-band FIR filters is presented. Based on the ideal frequency response of Mth-band filters, a closed-form frequency specification for the constituent filters is derived. Thus, the design problem of an original large-tap FIR filter is simplified to that of the constituent filters of significantly reduced length. In the meantime, the time-domain interpolation constraint can easily be satisfied by leaving one constituent filter as a function of other constituent filters designed. Using the proposed approach, an interpolation filter is designed and applied to image interpolation. Simulation results show that the designed Mth-band filter gives a superior interpolation performance in comparison to the commonly used cubic spline interpolation scheme.
Analytical Synthesis of Low-Sensitivity High-Order Voltage-Mode DDCC and FDCCII-Grounded R and C All-Pass Filter Structures

The difficulty of realizing the operations of addition and subtraction of a voltage-mode signal renders two special active elements, namely, differential difference current conveyors (DDCCs) and fully differential current conveyors (FDCCIIs), both of which have the ability to perform the operations of addition and subtraction, to become very important for voltage-mode analog filter design. Note that, for the design of operational transconductance amplifier and capacitor (OTA-C) filters, the recently reported analytical synthesis methods (ASMs) have been shown to be very effective for achieving simultaneously the three criteria, namely, all capacitors being grounded, the use of the minimum number of active and passive components, and the use of single-ended input OTAs. However, none of the ASMs uses DDCCs and FDCCIIs in the design of voltage-mode filters. In this paper, a method of realizing DDCC and FDCCII-based all-pass filter structures with either equal capacitances or equal conductances through a new ASM is presented. Only n current conveyors (the least number of active components), n grounded capacitors, and grounded resistors (the minimum number of passive components) are used for realizing an nth-order voltage-mode all-pass filter structure. Moreover, the new all-pass filter structure synthesized by the new ASM achieves very low individual as well as near-null group sensitivities just as in the case of the passive LC ladder filters, has very low power consumption, a low component spread for equal denominator conductance design, and a high input impedance which is attractive from the point of view of cascadability. Finally, H-Spice simulations, using 0.35-mum process and plusmn1.65-V supply voltages, are included and validate theoretical predictions.
Low-complexity video noise reduction in wavelet domain

This paper proposes a novel spatio-temporal filter for video denoising that operates entirely in the wavelet domain and is based on temporal decorrelation. For effective noise reduction, the spatial and the temporal redundancies, which exist in the wavelet domain representation of a video signal, are exploited. Using simple and closed form expressions, the temporal information in the wavelet domain is first decorrelated in order to minimize the redundancy. The decorrelated noise-free coefficients are then modeled using a generalized Gaussian prior. For spatial filtering of the noisy wavelet coefficients, a new, low-complexity wavelet shrinkage method, which utilizes the correlation that exists between subsequent resolution levels, is proposed. Experimental results show that the proposed scheme outperforms state-of-the-art spatio-temporal filters in time and wavelet domains, both in terms of PSNR and visual quality.
An efficient numerical scheme to compute 2-D stability thresholds

Stability thresholds (margins) of two-dimensional (2-D) digital filters were recently defined in terms of the singularities of the transfer function. Stability thresholds hold a close relationship to the settling time of the 2-D impulse response and can therefore serve as a measure of stability of 2-D digital filters. In this paper, a simple, unified procedure for the computation of stability thresholds (margins) for 2-D digital filters based on the z_1 and z_2 resultants of 2-D polynomials is presented. To illustrate the process, simple examples are also provided.
Multiplier-free structures for exact generation of natural powers of integers

It is shown that the sequence of an arbitrary natural power of consecutive integers can be generated without any multiplications as the impulse response of a multirate recursive structure. This multistage structure has a regular configuration consisting of multirate building blocks and accumulators. A nonrecursive structure is also developed for the generation of the power sequence for a prescribed finite length. This feedforward structure consists of layers of summation nodes interconnected in a regular manner. The two types of multiplier-free discrete-time structures generate the exact values of natural k/sup th/ powers of consecutive integers in a simple, regular and scalable manner.
On the on-line computation of DCT-IV and DST-IV transforms

Various options available for the on-line computation of discrete cosine transform-IV (DCT-IV) and discrete sine transform-IV (DST-IV) in hardware are considered and compared. A novel architecture for the simultaneous, real-time computation of both the transforms, based on the decomposition of the odd-time, odd-frequency discrete Fourier transform (O/sup 2/ DFT), is also proposed.
Reduced-Complexity Concurrent Systolic Implementation of the Discrete Sine Transform

In this paper, a reduced complexity algorithm for computation of the discrete sine transform (DST) is presented. The proposed algorithm can be used to compute an N-point DST from two pairs of [(M - l)/2]-point identical cyclic convolutions, where M is a prime number and M = N/2. A regular and locally connected linear systolic array architecture is also presented for concurrent pipelined VLSI implementation of all the four cyclic convolutions. The proposed structure is not only simpler, but also involves significantly less area-time complexity compared to that of the existing convolution-based DST structures. Unlike some of the existing structures, it does not need any control tag-bits for implementation of convolution-like operations
Design of Mth-band FIR filters based on generalized polyphase structure

In this paper, a generalized polyphase (GP) structure based design method for Mth-band FIR filters is presented. A few new transform matrices are proposed as seed matrix for generating a GP structure, which overcomes some limitations of the commonly used Hadamard transform. Under the framework of a general GP structure realization, the relationship between the original filter and the interpolator as well as the constituent filter is revealed from the frequency response perspective. This relationship facilitates the design problem of GP structure based FIR filters, since the original large-tap filter is reduced to a number of short-length constituent filters which can easily be designed according to the derived specifications. In particular, a closed-form frequency specification for the design of Mth-band filters is obtained. Design examples are given to illustrate the effectiveness of the proposed method
Z-transform of quantized ramp signal

The z-transform of a ramp signal, with a rational slope, which is quantized by rounding down using the floor function, or rounding up using the ceiling function, is computed explicitly. The principles of rational sampling rate conversion are employed in modeling the signal. A multirate sample rate conversion system and a single-rate infinite impulse response (IIR) digital filter are also proposed for the division-free generation of the signal. The systems involve integer coefficients and operate using integer arithmetic. To produce a quantized ramp signal with a zero-valued intercept, the multirate system requires no form of multiplication.
An efficient implementation of an edge detection algorithm

An efficient implementation of an edge detection algorithm with reduced computational complexity is proposed. The implementation is based on the principle that the execution time of an algorithm can be reduced if there is a priori knowledge of the parameters (coefficients of the mask) in the implementation, instead of considering the parameters and data as arbitrary entities. Fast implementation is achieved by exploiting the three basic properties of the edge operators. Experimental results of implementing several edge and other operators are presented and compared with those for the standard implementation. The results show a substantial improvement in execution time.<<ETX>>
Some results on the nature of a 2-dimensional filter function possessing certain symmetry in its magnitude response

Constraints on analogue and digital two-dimensional filter functions so that they possess various symmetries like quadrantal symmetry and circular symmetry in their magnitude responses are derived. An ideal circularly symmetric separable magnitude squared function is obtained. Approximation of the ideal function in analogue and digital domain is carried out and the contour plots of the responses of the resulting functions show that they are very nearly circularly symmetric.
Vehicle detection using TD2DHOG features

Histogram of oriented gradients (HOG) is often used for object detection in images. These HOG features of images can be referred to as 2DHOG when represented in a 2D matrix format instead of a 1D vector. In this paper, we propose a new vehicle detection algorithm by using 2DHOG in the discrete cosine transform (DCT) domain. The proposed technique consists of extracting 2DHOG from the input image and applying on it 2DDCT. This is followed by a low pass filtering in order to obtain novel features called as transform-domain 2DHOG (TD2DHOG). TD2DHOG is used with a classifier pyramid in order to reduce the multi-scale scanning cost. Experimental results show that the proposed algorithm when applied on two public vehicle detection datasets reduces the storage requirement of the classifier pyramid, while providing about the same performance as that provided by the state-of-the-art techniques.
A two-layer MPEG2-compatible video coding technique using wavelets

In this paper, a two-layer hierarchical video coding technique that is compatible with MPEG2 is presented. By using a simplified version of the Mallat algorithm, a video signal is decomposed as two constituent signals, the smoothed signal comprising low-frequency content and the edge part representing the high-frequency information. The smoothed signal is then encoded into an MPEG2 video stream, while the edge information is encoded by utilizing the chain code into an MPEG2 private stream. By applying this coding strategy, the artifacts such as the blocking effect that is usually present in conventional block-based coding schemes, especially at low bit rate, and the ringing effect which may occur in a wavelets-based method, are both overcome. Simulation results show that the proposed coding scheme is capable of producing high-quality reconstructed video signals.
Parameter estimation of Hodgkin-Huxley neuronal model using dual extended Kalman filter

Fitting biophysical models to real noisy data jointly with extracting fundamental biophysical parameters has recently stimulated tremendous studies in computational neuroscience. Hodgkin-Huxley (HH) neuronal model has been considered as the most detailed biophysical model for representing the dynamical behavior of the spiking neurons. In this paper, we derive, for the first time, the dual extended Kalman filtering (DEKF) approach for the HH neuronal model to track the dynamics and estimate the parameters of a single neuron from noisy recorded membrane voltage. As unscented Kalman filter (UKF) has been already applied to the HH model, a quantitative comparison between these methods is accomplished in our simulation for different signal to observation noise ratios. Our simulations demonstrate the high accuracy of DEKF in the prediction and estimation of hidden states and unknown parameters of the HH neuronal model. Faster implementation of DEKF (than UKF) makes it particularly useful in dynamic clamp technique.
Complexity of computation of a spanning tree enumeration algorithm

In 1968,  presented an algorithm to enumerate all the spanning trees of an undirected graph G . This algorithm starts with a known initial spanning tree of G , and generates all the other spanning trees along with certain spanning non-tree subgraphs of G . In this paper a detailed complexity analysis of Char's algorithm and methods to speed up the algorithm are discussed. Two heuristics for the selection of the initial spanning tree are suggested. These heuristics result in a considerable reduction in the number of spanning non-tree subgraphs generated. A technique called path compression, aimed at reducing the actual number of comparisons, is described. Computational results on several randomly generated graphs are presented to illustrate the improvement achieved.
A Note on "A Novel Current Memory Circuit for AMOLEDs"

PAPER on current memory circuit design (see Item 1 under References), which is published in IEEE TRANSACTIONS ON ELECTRON DEVICES, has drawn our attention. In this paper, a technique used to suppress the influence of charge injection in switched-current (SI) memory circuits, with an improvement in speed without relying on the matching of device characteristics, has been reported. The objective of this present note is to bring the attention of Lin and Shieh and the readers that the same technique with an identical circuit for an SI memory cell was published much earlier by Wang et al. in March 2000 (see Item 2 under References).
On BIBO- stability and nonessential singularities of the second kind

The open problem of the BIBO-stability of 2-D digital filters in the presence of nonessential singularities of the second kind on the distinguished boundary of the unit bidisk has attracted a lot of interest in the recent past [1]-[5]. One of the reasons for its importance is the practical need for the generation of BIBO-stable digital filters at the design stage.
Planar least squares inverse polynomials and practical-BIBO stabilization on n- dimensional linear shift-invariant filters

Development of simple procedures for the design of stable recursive n-dimensional (n -D) filters continues to be an important field of study. Because of the involved computations required to incorporate the stability constraints in the design stage, the search for a technique by which the stability problem could be separated from the approximation problem is of great importance. Continuing in this direction, some results concerning properties of PLSI (Planar Least Squares Inverse) polynomials vis-ai-vis Agathoklis and Bruton concept of practical-BIBO (Bounded-Input Bounded-Output) stability  are reported in this paper. It is shown that PLSI technique always leads to a BIBO stable n - D digital filter, with input signals whose region of support is unbounded at most in one dimension.
Error concealment for motion-compensated interpolation

Motion-compensated interpolation is usually employed at the receiver end in order to improve the quality of the video, when a low-bit-rate video is encoded in conjunction with frame dropping. The authors propose a scheme that can exploit the block-based motion vector field available at the decoder to avoid the complex motion estimation. The scheme is based on an iterative refinement technique that employs the finite-element method to efficiently conceal the interpolation errors caused by unfilled holes or overlapped pixels in the predicted frames. As a consequence, no pixel classification is needed in the proposed scheme, thus reducing substantially the computational complexity. The scheme is capable of concealing the errors in the homogeneous regions as well as in regions containing sharp edges. The proposed scheme is simulated with the original frames of a number of test sequences, as well as implemented with the H.264/AVC decoded frames. The results from these extensive simulations show that the proposed scheme results in reconstructed frames having a better visual quality and a lower computational complexity than the existing schemes.
A semi-blind algorithm for most significant tap detection in channel estimation of OFDM systems

In this paper, a semi-blind algorithm is proposed for the detection of most significant tap (MST) in the sparse channel estimation of OFDM systems. Based on an analysis of the second-order statistics of the signal received through a noise-free sparse channel, a direct relationship between the positions of the most significant taps (MST) of the sparse channel and the lags of the nonzero correlation functions is revealled, leading to an efficient semi-blind MST detection algorithm. By using the acquired MST position, a sparse least square channel estimate is then obtained. A number of computer simulation-based experiments are carried out to confirm the effectiveness of the proposed semi-blind MST detection algorithm and the associated sparse LS channel estimation method.
Despeckling of synthetic aperture radar images in the contourlet domain using the alpha-stable distribution

Speckle reduction has been a prerequisite for many SAR image processing tasks. This work presents a new approach for despeckling of SAR images in the contourlet domain using the alpha-stable distribution. It is shown that the alpha-stable distribution provides a good fit for the contourlet coefficients of an image, since it can capture the large peak and heavy tails of the distribution of the empirical data. This model is then exploited in a Bayesian maximum a posteriori estimator to restore the noise-free contourlet coefficients. The performance of the proposed despeckling method is evaluated using synthetically-speckled and real SAR images. Simulations are carried out using synthetically speckled images to investigate the performance of the proposed method, and compare it with that of some of the existing methods. The experimental results show that the proposed method can provide better preservation of the edges and can yield better visual quality as compared to some of the existing methods.
On the design of a broad class of 2-D recursive digital filters with fan, diamond and elliptically-symmetric responses

This paper deals with the design of a broad class of 2-D recursive digital filters including general fan, diamond and elliptically-symmetric filters. At first, the explicit design of quadrant and /spl plusmn/45/spl deg/ fan filters is reviewed. A full-plane diamond filter (both axes are nearly of length 2 /spl pi/) can easily be obtained through an appropriate transformation of a /spl plusmn/45/spl deg/ fan filter. Using this diamond filter as a prototype, a very simple spectral transformation is then proposed to design full-plane circularly-symmetric filters (radius /spl ap//spl pi/). These filters share the same lattice wave digital structure and employ only first or second order all-pass sections which can be realized by two-port adaptors. They provide very desirable properties such as low sensitivity, high dynamic range and good stability even under finite arithmetic conditions. Using the above mentioned filters as prototypes, a multirate approach is then introduced to deal with the design of fan filters with arbitrary angle and orientation, diamond and elliptically-symmetric filters with arbitrary length of axes. Finally, some design examples are given.
2-D fast Kalman algorithms for adaptive parameter estimation of nonhomogeneous Gaussian Markov random field model

In this paper, a two-dimensional (2-D) nonhomogeneous Gaussian Markov Random Field (GMRF) model is presented and the problem of adaptive parameter estimation for this model is addressed. Two 2-D fast Kalman algorithms are proposed as extensions of the 1-D fast Kalman algorithm, which utilize the shift-invariant and near-to-Toeplitz properties of the coefficient matrix of the normal equation resulting from the least squares (LS) criterion. In the first algorithm the space-varying model parameters are updated by sliding a data window with a constant size. By first shifting the data window from left to right and then from top to bottom, the spatial adaptive algorithm covers a whole image. In the second algorithm the model parameters are updated by absorbing new pixel data or deleting old pixel data. The computational complexities of the proposed two algorithms are O(Lm/sup 2/)+O(L/sup 2/m) MADPR (Multiplications And Divisions Per Recursion) acid O(m/sup 3/2/) MADPR respectively, compared with O(L/sup 2/m/sup 2/)+O(m/sup 3/) and O(m/sup 3/) needed in the corresponding direct least squares method, m and L being respectively the total number of model parameters to be estimated and the size of data window. For computer simulation two sample images which obey two sets of known parameters are first synthesized, and are then merged, resulting in a non-homogeneous image. It is shown that the 2-D fast Kalman algorithms developed in the paper reduce the computational complexity significantly and can track the model parameters very well. The estimated model parameters are as same as those obtained by using direct LS method. The algorithms derived in this paper can be used in many applications where an image is considered as a nonstationary one.
A subspace constrained constant modulus algorithm for blind array

It is known that the stochastic gradient descent (SGD)-based constant modulus algorithm (CMA) has the drawback of slow convergence rate. It is also known that under some weak conditions, all local minima of CMA are identical to that of a CMA which is constrained in signal subspace. Based on this property, we propose a subspace-constrained CMA that is able to increase the convergence rate of the conventional SGD-CMA. To reduce the computational complexity, a technique referred to as projection approximate subspace tracking with deflation (PASTd) is used to calculate the signal subspace. Our simulation shows that the proposed algorithm is significantly superior to the conventional SGD-CMA both in the convergence rate and in the sensitivity to the step size.
Implementation of a voice activity detection and comfort noise generation algorithm

Voice activity detection and comfort noise generation (VAD-CNG) algorithms are widely employed in packet voice communication systems to reduce transmission bandwidth. This paper is devoted to the investigation of effective implementations of a modified version of a well-established fixed-point data-dependent VAD-CNG algorithm of Nortel Network on a TMS320C5402DSK DSP board. Certain optimizations that target reduction in the implementational complexity of the algorithm are introduced. Experimental results show that over 80% of the reduction in the implementational complexity is achieved through the proposed optimizations, making it possible to incorporate such a VAD-CNG algorithm into a practical real-time voice communication system. A real-time audio codec system is built in the laboratory to demonstrate a real-time implementation of this algorithm.