nils-herrmann/clean_scirepeval huggingface dataset:
Integer fast Fourier transform

A concept of integer fast Fourier transform (IntFFT) for approximating the discrete Fourier transform is introduced. Unlike the fixed-point fast Fourier transform (FxpFFT), the new transform has the properties that it is an integer-to-integer mapping, is power adaptable and is reversible. The lifting scheme is used to approximate complex multiplications appearing in the FFT lattice structures where the dynamic range of the lifting coefficients can be controlled by proper choices of lifting factorizations. Split-radix FFT is used to illustrate the approach for the case of 2/sup N/-point FFT, in which case, an upper bound of the minimal dynamic range of the internal nodes, which is required by the reversibility of the transform, is presented and confirmed by a simulation. The transform can be implemented by using only bit shifts and additions but no multiplication. A method for minimizing the number of additions required is presented. While preserving the reversibility, the IntFFT is shown experimentally to yield the same accuracy as the FxpFFT when their coefficients are quantized to a certain number of bits. Complexity of the IntFFT is shown to be much lower than that of the FxpFFT in terms of the numbers of additions and shifts. Finally, they are applied to noise reduction applications, where the IntFFT provides significantly improvement over the FxpFFT at low power and maintains similar results at high power.
Discriminability Limits in Spatio-Temporal Stereo Block Matching

Disparity estimation is a fundamental task in stereo imaging and is a well-studied problem. Recently, methods have been adapted to the video domain where motion is used as a matching criterion to help disambiguate spatially similar candidates. In this paper, we analyze the validity of the underlying assumptions of spatio-temporal disparity estimation, and determine the extent to which motion aids the matching process. By analyzing the error signal for spatio-temporal block matching under the sum of squared differences criterion and treating motion as a stochastic process, we determine the probability of a false match as a function of image features, motion distribution, image noise, and number of frames in the spatio-temporal patch. This performance quantification provides insight into when spatio-temporal matching is most beneficial in terms of the scene and motion, and can be used as a guide to select parameters for stereo matching algorithms. We validate our results through simulation and experiments on stereo video.
Investigating Latency in GNU Software Radio with USRP Embedded Series SDR Platform

Software-Defined Radio (SDR) is a radio technology that most of conventional radio components are implemented in software. Besides the advantages like re-configurability and flexibility, a SDR system has to face a critical challenge on real-time processing due to high jitter and latency. Thus, understanding latency in SDR systems is very important. This paper focuses on investigating the latency of a popular SDR platform - GNU Software Radio with a new Universal Software Radio Peripherals (USRP) device -USRP Embedded Series E100. This research investigates and analyzes the reasons of the delays by considering all the buffering mechanisms in the platform. After that, we verify and quantify them by using three experimental methods. The first method is to calculate the whole delay of the SDR system by measuring the round-trip time (RTT). The second method measures subparts of the whole latency by using timestamp during a packet transmission process. The third approach is designated to measure the latency of the hardware part and bus communication part. We believe this study offers the better understanding of the latency in a new embedded USRP series - USRP E100 with GNU Software Radio platform.
Rate distortion optimization for bidirectional scalable motion model

The fully scalable motion model (SMM) is proposed for scalable video codec by taking advantage of motion information scalability. In previous work, SMM has been improved to support hierarchical B frame and bidirectional or multidirectional motion estimation. It yields better results comparing to method using unidirectional motion estimation. However, the process of bidirectional or multidirectional rate distortion optimization motion estimation is very complex and is the most time-consuming task in the encoding process. We present several algorithms to reduce its complexity and show corresponding simulation to compare their performance.
Circularly Polarized Bandwidth-Enhanced Crossed Dipole Antenna With a Simple Single Parasitic Element

A method of using a simple single parasitic element to significantly enhance a 3-dB axial-ratio (AR) bandwidth of a crossed dipole antenna is presented. This approach is verified by introducing one bowtie-shaped parasitic element between two arms of crossed bowtie dipoles to generate additional resonance and thereby significantly broadening AR bandwidth. The final design, with an overall size of 0.79 <italic>λ<sub>o</sub></italic> × 0.79 <italic> λ<sub>o</sub></italic> × 0.27 <italic>λ<sub>o</sub></italic> (<italic>λ<sub>o</sub></italic> is the free-space wavelength of circular polarized center frequency), resulted in very large measured –10-dB impedance and 3-dB AR bandwidths ranging from 1.9 to 3.9 GHz (∼68.9%) and from 2.05 to 3.75 GHz (∼58.6%), respectively. In addition, the antenna also yielded a right-hand circular polarization with stable far-field radiation patterns and an average broadside gain of approximately 8.2 dBic.
Rate-distortion optimized bitstream extractor for motion scalability in scalable video coding

Motion scalability is designed to improve the coding efficiency of a scalable video coding framework, especially in the medium to low range of decoding bit rates or spatial resolutions. In order to fully benefit from the superiority of motion scalability, a rate-distortion optimized bitstream extractor, which determines the optimal motion quality layer for each decoding scenario, is required. In this paper, the determination process first starts off with a brute force searching algorithm. Although guaranteed by the optimal performance within the search domain, it has high computational complexity. Two properties, i.e. the monotonically non-decreasing property and the unimodal property, are then derived to accurately describe the rate-distortion behavior of motion scalability. Based on these two properties, modified searching algorithms are proposed to reduce the complexity by a factor up to 5.
Efficient Design of Cosine-Modulated Filter Banks via Convex Optimization

This paper presents efficient approaches for designing cosine-modulated filter banks with linear phase prototype filter. First, we show that the design problem of the prototype filter being a spectral factor of 2M th-band filter is a nonconvex optimization problem with low degree of nonconvexity. As a result, the nonconvex optimization problem can be cast into a semi-definite programming (SDP) problem by a convex relaxation technique. Then the reconstruction error is further minimized by an efficient iterative algorithm in which the closed-form expression is given in each iteration. Several examples are given to illustrate the effectiveness of the proposed method over the existing ones.
Optimal filter bank reconstruction of periodically undersampled signals

A multirate filter bank model is considered for reconstruction of periodically sampled signals. In contrast to many previous methods which considered perfect reconstruction of deterministic signals, this approach uses a known discrete-time cyclostationary signal model to find a minimum mean-squared error reconstruction solution. A primary advantage of this approach is that it does not require a minimum sampling density, allowing optimal solutions to be determined in cases of undersampling. This allows for consideration of a wide range of generalized sampling problems under a single framework. An example, with simulation results, is presented.
Generalized lapped biorthogonal transforms with integer coefficients

Invertible transforms with integer coefficients are highly desirable because of their fast, efficient, VLSI-suitable implementations and their lossless coding capability. In this paper, a large class of generalized lapped biorthogonal transforms with integer coefficients (IGLBT) is presented. The IGLBT also possesses a fast and efficient lattice that structurally enforces both linear phase and exact reconstruction properties. Preliminary image coding experiments show that the IGLBT yields comparable objective and subjective performance to those of popular state-of-the-art transforms with floating-point coefficients.
Theory and design of perfect reconstruction transmultiplexers and their relation to perfect reconstruction QMF banks

The theory of transmultiplexers involves the design of 
filters for interconversion between Time Domain Multiplexing (TDM) and Frequency Division Multiplexing (FDM), such that the undesirable Crosstalk is minimized. 
In TDM → FDM → TDM conversion, the perfect reconstruction 
trans-multiplexer (PR-TMUX) achieves complete Crosstalk Cancellation (CC) and is distortion-free. In this 
paper, we present an analysis of the PR-TMUX based 
on the polyphase component matrices of the filter banks used in TDM → FDM and FDM → TDM conversion respectively. Using that, a necessary and sufficient condition for 
complete CC is obtained. The close relation between 
PR-TMUX filters and PR-QMF banks is used to obtain 
a direct design procedure for PR-TMUX filters.
Towards a sound modular model checking of collaboration-based software designs

Collaboration-based designs [K. Fisler et al. (2001), T. T. Nguyen et al. (2003), Y. Smaragdakis et al. (1998)] are an effective software development approach due to its achievement in separation of concerns [G. Kiczales et al., (1997), P. Tarr et al. (1999)]. These designs also demand a new model checking technique allowing to prove system correctness by verifying each collaboration individually with a minimum assumption about other collaborations. To verify a collaboration of multiple actors, a typical technique consists of constructing a standard cross-product of actor statecharts as global state space and then checking properties with respect to that global space. We initially point out some drawbacks of a previous approach [K. Fisler et al. (2001)] in verifying collaboration. Then, in addition to intra-object behaviors in statecharts as of [K. Fisler et al. (2001)], we first improve the technique by imposing additional constraints to model checking process via protocol invariants which are essentially inter-object behaviors. Due to these additional constraints, state space is reduced and more importantly, our model reflects more accurately about system behavior by eliminating those unreachable states. Second, a more general form, i.e. multiple exit and re-entry states, of the interface between two collaborations is used instead of a fixed interface with single exit and re-entry states. Some pre-processing work on reentry states and solutions to specifics of properties to be verified are also discussed regarding to the soundness of the verification algorithm.
Optimal reconstruction of periodically sampled signals with probabilistic timing delays

A periodic sampling process can be modelled through multiple parallel uniform sampling processes with distinct timing delays. In this paper, these timing delays are considered as random variables with known discrete probability density functions. An optimal reconstruction method, which minimizes the expected time-averaged mean squared error, is developed using a multirate filter bank structure. A design example is presented with simulation results demonstrating the superior performance of this method over standard reconstruction techniques based on deterministic timing delay models.
Image Denoising using Shiftable Directional Pyramid and Scale Mixtures of Complex Gaussians

In this paper, a modified version of the complex directional pyramid (PDTDFB) is proposed. Unlike the previous approach, the new FB provides approximately tight-frame decomposition. We introduced the complex Gaussian scale mixture (CGSM) for modeling the distribution of complex directional wavelet coefficients. The statistical model is then used to obtain the denoised coefficients from the noisy image decomposition by Bayes least squares estimator. Performance of the denoised images using the PDTDFB is compared to the conventional transforms including the orthogonal wavelet, the contourlet and the steerable pyramid. The experiments show that the PDTDFB could achieve higher quality image denoising than the wavelet and the contourlet with the hard thresholding method, and is comparable to the steerable pyramid in terms of mean squared error (MSE) and perceptual image quality (SSIM) with the Bayes least squares estimator.
Full-wavelength dipole antenna on a membrane covered with a lens for a high gain terahertz photomixer

This paper presents a full-wavelength dipole antenna on a membrane covered with a lens to improve the efficiency and directivity of a terahertz photomixer. A full-wavelength dipole antenna supported by a membrane structure has low directivity. An extended hemispherical lens introduced in front of the antenna can achieve high directivity. The optimized antenna had a 3818-Ω input resistance and a 71.2% radiation efficiency at the 1.07-THz resonance frequency. The total efficiency of this structure is approximately 6.8 times that of a full-wavelength dipole antenna with almost the same directivity.
Symmetric extension methods for M-channel PR LP FIR analysis/synthesis systems

In this paper we study support preservative (SP) symmetric extension methods for M-channel perfect-reconstruction linear-phase FIR analysis/synthesis systems. For a given finite-duration sequence and a given FIR linear-phase filter bank, necessary and sufficient conditions are derived such that SP symmetric extensions exist. Moreover, explicit methods are given to construct the extensions. Results are extended to linear-phase paraunitary filter banks. Design examples and experiments in 2, 3, 4 and 8 channel cases are included to verify the theory.<<ETX>>
A Novel Motion Compensated Frame Interpolation Based on Block-Merging and Residual Energy

In this paper, a novel motion compensated frame interpolation (MCFI) algorithm by merging blocks that have unreliable motion vectors (MVs) based on their residual errors is proposed. Unlike the conventional methods that find true motion using smaller blocks and vector median filter, we proposed to find one single motion vector to represent a group of adjacent macroblocks (MBs) where the conventional MCFI methods are likely to fail, likely to fail. The proposed method is able to preserve the structure of different objects and their edge information, without requiring complicated edge detection and object-based motion estimation. Experimental results show that the proposed scheme improves both visual quality and PSNR, especially in the areas with different motions and the motion boundary
Kernel Resolution Synthesis for Superresolution

This work considers a combination classification-regression based framework with the proposal of using learned kernels in modified support vector regression to provide superresolution. The usage of both generative and discriminative learning techniques is examined first by assuming a distribution for image content for classification and then providing regression via semi-definite programming (SDP) and quadratically constrained quadratic programming (QCQP) problems. The advantage of the proposed method over other learning-based superresolution algorithms include reduced problem complexity, specificity with regard to image content, added degrees of freedom from the nonlinear approach, and excellent generalization that a combined methodology has over its individual counterparts.
On the problem of reconstructing a segment of a wideband signal using a digital filter bank

The design process is reduced to designing the filter bank to satisfy a set of conditions and it is known that the reconstructed signal always possesses some alias and distortion. It is the present objective to find the necessary and sufficient conditions on the filters so that the resulting QMF (quadrature mirror filter) bank cancels most alias components. Having found these conditions, the author suggests an algorithm to design the PAC (partial alias cancellation) QMF bank. Examples are given to demonstrate the theory.<<ETX>>
Uniform Discrete Curvelet Transform

An implementation of the discrete curvelet transform is proposed in this work. The transform is based on and has the same order of complexity as the Fast Fourier Transform (FFT). The discrete curvelet functions are defined by a parameterized family of smooth windowed functions that satisfies two conditions: i) 2π periodic; ii) their squares form a partition of unity. The transform is named the uniform discrete curvelet transform (UDCT) because the centers of the curvelet functions at each resolution are positioned on a uniform lattice. The forward and inverse transform form a tight and self-dual frame, in the sense that they are the exact transpose of each other. Generalization to M dimensional version of the UDCT is also presented. The novel discrete transform has several advantages over existing transforms, such as lower redundancy ratio, hierarchical data structure and ease of implementation.
A novel spectral factorization method and its application in the design of filter banks and wavelets

One of the difficulties encountered in spectral factorization is achieving computational accuracy when computing a spectral factor whose zeros are on the unit circle and/or the order is high. An iterative approach is presented for computing the spectral factor accurately. It is shown that the new method performs well and can be used in the design of filter banks satisfying perfect reconstruction and orthonormal compactly supported wavelets. Design examples are included.<<ETX>>
Improved approach for design of perfect reconstruction FIR QMF banks, with lossless lattice structures

A property of FIR (finite-impulse response) lossless systems is introduced, leading to substantial improvement in the sign procedure for perfect-reconstruction QMF (quadrature mirror filter) banks. The property enables the designer to initialize the coefficients of a lattice structure (which characterizes the analysis bank), in such a way as to speed up to the convergence. A design example is provided. Compared to other methods, the proposed method is shown to converge faster, and always leads to much improved attenuation characteristics for a given filter length.<<ETX>>
A Frame-Level Rate Control Scheme Based on Texture and Nontexture Rate Models for High Efficiency Video Coding

In this paper, a frame-level rate control scheme is proposed based on texture and nontexture rate models for High Efficiency Video Coding (HEVC). Due to more complicated coding structures and the adoption of new coding tools, the statistical characteristics of transform residues are significantly different depending on the depth levels of coding units (CUs) from which the residues are obtained. A new texture rate model is constructed for the transform residues, which are categorized into three types of CUs: low-, medium- and high-textured CUs. One single Laplacian probability PDF model is used for each residue category to derive a rate-quantization model. Based on the Laplacian PDF, a simplified rate model for texture bits is derived using entropy. In addition, an analytic rate model for nontexture bits is proposed, which also takes into account the different characteristics of nontexture bits occurring in various depths of CUs in HEVC. The nontexture bitrates are modeled based on the linear relation between the total nontexture data and the dominant nontexture data in each CU category. Based on the proposed rate models for the texture and nontexture bits, accurate rate control can be achieved owing to more precise rate estimation. The experimental results show that the proposed rate control scheme achieves the average PSNR with 0.44 dB higher and the average PSNR standard deviation of 0.32 point lower with the buffer status levels maintained very close to target buffer levels, compared to the conventional methods. Finally, the proposed rate control scheme remarkably outperforms the conventional schemes especially for the sequences of complex texture and large motion.
Improving streaming video segmentation with early and mid-level visual processing

Despite recent advances in video segmentation, many opportunities remain to improve it using a variety of low and mid-level visual cues. We propose improvements to the leading streaming graph-based hierarchical video segmentation (streamGBH) method based on early and mid level visual processing. The extensive experimental analysis of our approach validates the improvement of hierarchical supervoxel representation by incorporating motion and color with effective filtering. We also pose and illuminate some open questions towards intermediate level video analysis as further extension to streamGBH. We exploit the supervoxels as an initialization towards estimation of dominant affine motion regions, followed by merging of such motion regions in order to hierarchically segment a video in a novel motion-segmentation framework which aims at subsequent applications such as foreground recognition.
Optimal Design of FIR Triplet Halfband Filter Bank and Application in Image Coding

This correspondence proposes an efficient semidefinite programming (SDP) method for the design of a class of linear phase finite impulse response triplet halfband filter banks whose filters have optimal frequency selectivity for a prescribed regularity order. The design problem is formulated as the minimization of the least square error subject to peak error constraints and regularity constraints. By using the linear matrix inequality characterization of the trigonometric semi-infinite constraints, it can then be exactly cast as a SDP problem with a small number of variables and, hence, can be solved efficiently. Several design examples of the triplet halfband filter bank are provided for illustration and comparison with previous works. Finally, the image coding performance of the filter bank is presented.
Performance analysis of multicarrier modulation systems using cosine modulated filter banks

We compare the performance of biorthogonal cosine modulated transmultiplexer filter banks with today's multicarrier modulation systems whose transceivers are based on DFT. In contrast to early works on transmultiplexer filter banks that concentrated on the derivation of perfect reconstruction constraints of the filter bank or prototype design, this study takes into consideration a typical twisted pair copper line transmission channel into consideration and examines the influence of different system parameters as filter length, number of channels, and the overall system delay on the distortion at the receiver. Biorthogonal filter banks have the advantage that filter length and overall system delay can be chosen independently. Restricting the equalizer at the receiver to a single scalar tap per subchannel, we show that cosine-modulated filter banks outperform DFT based multicarrier systems without a guard interval and obtain a similar performance to DFT based systems with a guard interval and time domain equalization but at a lower computational cost and a higher throughput data rate.