nils-herrmann/clean_scirepeval huggingface dataset:
Enhanced 3d tree model simplification and perceptual analysis

The effectiveness of 3D tree model simplification techniques and their objective and subjective performance evaluations are examined in this work. The simplification techniques developed in [1, 2] were based on pixel-based metrics, which did not consider the tree model's leaf density. For performance improvement, we perform simplification based on the tree leaf density of rendered images viewed from multiple angles. Furthermore, objective performance analysis is conducted to evaluate how well different algorithms are able to simplify tree models that appear as close to the original tree model with a given budget on the number of tree leaves in the model. To this end, a performance metric based on the Gabor filter is developed to analyze the orientation and spatial relationship within the rendered tree models. Finally, subjective evaluation is conducted by a group of 23 people. Both the objective and the subject evaluations reach a consistent conclusion; namely, the newly proposed densitybased simplification technique offers the best results.
A parallel 2-level 4-color SOR method

A 2-level 4-color SOR method is proposed for the solution of the 9-point discretization of the Poisson equation on a square in parallel. Instead of examining the Jacobi iteration matrix in the space domain, we consider an equivalent but much simpler 4-color iteration matrix in the frequency domain. A 2-level SOR method is introduced to increase the convergence rate for the frequency-domain iteration matrix. At a first level, the red and orange points, and then the black and green points are treated as groups, and a block SOR iteration is performed on these two groups. At a second level, another SOR iteration is used to decouple values of the solution at the red and orange points, and then at the black and green points. The optimal relaxation parameters for these two relaxation levels are determined.
An EM-based joint maximum likelihood estimation of carrier frequency offset and channel for uplink OFDMA systems

A maximum likelihood estimator (MLE) based on expectation maximization (EM) method is presented to jointly estimate the carrier frequency offset (CFO) and the channel of each user in uplink OFDMA systems. The proposed MLE distinguishes itself from existing methods by its applicability to any arbitrary carrier assignment schemes. The proposed MLE achieves high computational efficiency by transforming a multidimensional maximization problem into a number of substantially smaller separate maximization problems. Computer experiments have been conducted to confirm the effectiveness of the proposed estimators in estimation accuracy and robustness against the near-far effect.
A spatial-domain error concealment method with edge recovery and selective directional interpolation

A low complexity spatial-domain error concealment method is proposed to reconstruct still images and intra-coded (I) frames in video when they are transmitted through unreliable channels. The proposed concealment algorithm works with the following steps. First, missing edges in a lost macroblock (MB) are detected and recovered using gradient data. Then, the lost MB is implicitly divided into several segments along the recovered edges. Finally, each pixel in a segment is directionally interpolated from boundary pixels adjacent to the segment. Experimental results show that the proposed algorithm can recover high as well as low frequency information in lost MBs and provide better visual quality in comparison with the conventional spatial domain interpolation.
Continually traffic accommodating Internet streaming video

A new way to implement the Internet modem video transmission is presented. This system is capable of continually accommodating its bitstream size in response to changing network conditions. The key idea is to adopt an adaptive least mean squares (LMS) controller to orchestrates an H.263+ encoder rate control at the server end as well as a fast frame interpolation at the client end. It is demonstrated that the user datagram protocol (UDP) packet loss is significantly reduced and a smooth video display can be achieved.
Performance analysis of multistage linear groupwise successive interference cancellation via graphical approach

The performance of the multistage linear groupwise successive interference canceller (GSIC) in long-code direct sequence-code division multiple access (DS-CDMA) systems is analyzed in this research. We adopt a graphical approach to calculate the conditional mean and variance of the output signal of the receiver at an arbitrary stage. The computation of such statistics involves the evaluation of high order moments of large size matrices and, therefore, has a very high complexity, which increases exponentially with the number of stages of the receiver. The solution of this problem via graph theory allows very accurate evaluation of the conditional mean and variance. Simulation results show that the proposed method is able to estimate the bit error probability (BEP) with high accuracy.
A progressive view-dependent technique for interactive 3-D mesh transmission

A view-dependent graphics streaming scheme is proposed in this work that facilitates interactive streaming and browsing of three-dimensional (3-D) graphics models. First, a 3-D model is split into several partitions. Second, each partition is simplified and coded independently. Finally, the compressed data is sent in order of relevance to the user's requests to maximize visual quality. Specifically, the server can transmit visible parts in detail, while cutting out invisible parts. Experimental results demonstrate that the proposed algorithm reduces the required transmission bandwidth, and provides an acceptable visual quality even at low bit rates.
SIMD - efficient loop unrolling design for embedded multimedia applications

Due to the rising complexity of modern embedded media applications (EMAs), compilers must have the capability to exploit superword level parallelism (SLP). This work analyzes the memory access patterns found in EMAs and presents a scheme to calculate the loop unrolling factor to utilize these patterns fully to generate efficient single instruction multiple data (SIMD) instructions. The loop nest is also considered for actual memory access patterns, which can be used to improve the efficiency of the compiler. We observe a performance improvement by an average factor of 12 times for manual experiments conducted on the TriMedia TM-1300 processor for the H.264 encoding application.
Design of Multiuser Collusion-Free Hiding Codes with Delayed Embedding

The design of collusion-free hiding codes for a large number of users in a media distribution scenario is considered in this work. To increase the number of users, we propose to assign the same codeword repetitively to multiple users but with a different amount of delay. It is shown that, when the proposed system is under collusion, it is equivalent to a communication system with a multipath channel. Then, the identification performance for each user code can be improved by multipath channel estimation and adaptive equalization methods. We present a set of collusion-free codes called OSIFT (orthogonal spreading followed by the inverse Fourier transform) and demonstrate that OSIFT codes are robust against a generalized collusion attack in an exemplary audio watermarking system with a large number of users by computer simulation.
Secrecy-Enhancing Signaling Schemes for Fast-Varying Wiretap Channels With Only CSI at the Transmitter

This paper proposes secrecy-enhancing signaling schemes to exploit the advantages of having only channel state information (CSI) at the transmitter, but no (or limited) CSI at the receiver and the eavesdropper in fast-fading wiretap channels and also in wiretap channels with Gaussian interference. With only CSI at the transmitter, the transmit signaling can be designed to precompensate for the distortion or the interference on the main channel to facilitate decoding at the receiver while leaving the eavesdropper confused by the uncertainties of its own channel. In fading wiretap channels, truncated channel-inversion and phase-compensation schemes are proposed to achieve this task. Here, truncation is used so that transmission occurs only when the main channel is sufficiently reliable. In wiretap channels with Gaussian interference, a truncated interference-nulling scheme is proposed to enable interference precancellation at the transmitter. The proposed signaling schemes exploit the advantages of having only CSI at the transmitter without employing more complex encoding schemes. The achievable secrecy rates are derived using Gaussian input, and approximate expressions are proposed for the optimization of system parameters. The effectiveness of the proposed transmission schemes and the advantages of having only CSI at the transmitter are demonstrated through numerical simulations.
Stereo Matching via Disparity Estimation and Surface Modeling

Two new techniques are proposed to improve stereo matching performance in this work. First, to address the disparity discontinuity problem in occluded regions, we present a disparity estimation procedure, which consists of two steps; namely, a greedy disparity filling algorithm and a least-squared-errors (LSE) fitting method. Second, it is observed that the existing fronto-parallel model with color segmentation is built upon the piecewise constant surface approximation, which is however not efficient in approximating slanted or curved objects. We use a piecewise linear surface model to represent 3-dimensional (3D) geometric structure for better surface modeling. The proposed stereo matching system with these two new components is evaluated with Middlebury data sets with excellent quantitative and qualitative results.
Computationally Efficient Dynamic Code Assignment Schemes With Call Admission Control (DCA-CAC) for OVSF-CDMA Systems

This paper investigates computationally efficient suboptimal dynamic code assignment (DCA) schemes with call admission control (CAC) for orthogonal variable spreading factor code-division multiple-access systems. We examine two different approaches. The first approach reduces the complexity of the DCA scheme by partitioning the total resource (either capacity or service class) into several mutually exclusive subsets and assigns each subset of resource to a group of users in proportion to the corresponding traffic load. The second approach reduces the complexity of the optimal CAC scheme with the Markov decision process over an infinite time horizon by a suboptimal CAC policy, which is designed by observing the behavior of system dynamics over only two consecutive stages upon the arrival of a call. It is demonstrated by numerical evaluation that the proposed schemes achieve an average data throughput close to that of the optimal DCA-CAC performance while demanding a much lower computational complexity in their design and implementation.
Scheduling design for distributed video-on-demand servers

An online request migration scheme and a dynamic content update strategy for distributed video-on-demand (VoD) systems are proposed in this work to reduce the service failure rate and the server-side network bandwidth consumption. By improving the random early migration (REM) scheme that was designed for a centralized VoD server system, we propose a cost-aware REM (CAREM) scheme to reduce the network bandwidth consumption of the migration in a distributed environment. A dynamic content update strategy is also proposed based on the server-video affinity metric to reconfigure video copies assigned to media servers. Extensive simulations show that CAREM together with the dynamic content update strategy can reduce both the failure rate and the server bandwidth consumption.
Refinement of 3D meshes by selective subdivision

An adaptive subdivision method is proposed in this work for automatic post-processing of a 3D graphic model of coarse resolution. The method is an improved version of the Modified Butterfly Scheme (MBS) developed by Zorin et al. The main contribution of this work is to exploit the local smoothness information of a surface for adaptive refinement of a coarse 3D graphic model. With this approach, we can avoid unnecessary subdivision in relative smooth legions. The new algorithm not only reduces the computational complexity but also reduces the storage space. It is demonstrated via experiments that a more visual-pleasing representation can be obtained.
Automatic Human Mocap Data Classification

Automatic classification of human motion capture (mocap) data has many commercial, biomechanical, and medical applications and is the principal focus of this paper. First, we propose a multi-resolution string representation scheme based on the tree-structured vector quantization (TSVQ) to transform the time-series of human poses into codeword sequences. Then, we take the temporal variations of human poses into account via codeword sequence matching. Furthermore, we develop a family of pose-histogram-based classifiers to examine the spatial distribution of human poses. We analyze the performance of the temporal and spatial classifiers separately. To achieve a higher classification rate, we merge their decisions and soft scores using novel fusion methods. The proposed fusion solutions are tested on a wide variety of sequences from the CMU mocap database using five-fold cross validation, and a correct classification rate of 99.6% is achieved.
Fast 2D intra prediction (2DIP) mode decision for image and video coding

A 2D intra prediction with geometrical manipulations (2DIP) was proposed in  to enhance the intra coding performance of H.264/AVC. However, the complexity of 2DIP is high if the full search scheme is used. In this work, we investigate ways to speed up the intra prediction mode decision for 2DIP. To achieve this, we first conduct a block correlation analysis that reveals the unique characteristics of 2DIP. Based on the analysis, a fast 2DIP search scheme is proposed to reduce the encoder complexity, where a block classification method is used to identify blocks using LIP only, a good initial search position is predicted and a block pruning technique is introduced. It is shown by experimental results that the fast 2DIP search can reduce the complexity of the full search significantly with little loss in the RD performance.
Throughput Analysis of Feedback-Directed Adaptive MIMO-OFDM Systems

The throughput performance of adaptive multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) system without channel station information (CSI) in priori is investigated in this research. First, throughput scaling factor (pre-log factor) of an nt transmit antennas, nr receive antennas MIMO-OFDM with total N subcarriers is asymptotically equal to n* (1- n* L/(MN)), where n* = min(nt, nr) and M is the number of OFDM blocks experienced a constant channel. Second, feedback directed adaptive schemes can achieve the pre-log factor of the lower bound. Third, diversity-multiplexing gain tradeoff of variable-rate systems has been shown to have the same behavior as MIMO systems employed with random Gaussian codewords. Finally, it is shown that throughput of OFDMA with opportunistic scheduling performs better than traditional OFDM-TDMA scheduling with constant enhancement independent of SNR in multiuser downlink environment.
Enhanced speech separation in room acoustic environments with selected binaural cues

We propose a robust technique to separate audio sources received by a microphone array in a room acoustic environment with an underdetermined mixing process (i.e., the number of sources is larger than the number of mixtures). Our scheme consists of two stages: 1) estimation of mixing parameters and 2) recovery of source signals. For the first stage, contrary to the traditional DUET-type methods that exploit all binaural cues, we estimate the mixing parameters by selecting a reliable subset of binaural cues based on the phase determinacy condition and source sparsity. As a result, we can determine the mixing parameters successfully even in a reverberant environment with longer time delay. Then, proper mathematical tools are applied to the underdetermined linear system to recover the original audio sources for the second stage. Experimental results on simulated data in a room acoustic environment are given to show a significant gain over the DUET-type method in audio source separation.
Video analysis and classification for MPEG-7 applications

Current information and communication technologies provide the infrastructure to send bits anywhere, but do not presume to handle information at the semantic level. Consequently, the huge amount of multimedia data imposes people a heavy burden of manipulating, including searching/choosing, interpreting, skimming, and integrating information. Thus automatic video content analysis, including video semantic category classification is necessary for various MPEG-7 applications, such as video content-based retrieval databases, on-line video indexing and filtering, video summaries for browsing systems and so on. We implemented and applied a set of simple visual/motional feature descriptors to our proposed video semantic category classification system for various applications.
Enhancing Physical-Layer Secrecy in Multiantenna Wireless Systems: An Overview of Signal Processing Approaches

This article provides an overview of the signal processing techniques used to enhance secrecy in the physical layer of multiantenna wireless communication systems. Motivated by results in information theory, signal processing techniques in both the data transmission and the channel estimation phases have been explored in the literature to enlarge the signal quality difference at the destination and the eavesdropper. In the data transmission phase, secrecy beamforming and precoding schemes are used to enhance signal quality at the destination while limiting the signal strength at the eavesdropper. Artificial noise (AN) is also used on top of beamformed or precoded signals to further reduce the reception quality at the eavesdropper. In the channel estimation phase, training procedures are developed to enable better channel estimation performance at the destination than at the eavesdropper. As a result, the effective signal-to-noise ratios (SNRs) at the two terminals will be different and a more favorable secrecy channel will be made available for use in the data transmission phase. Finally, future research directions are discussed.
Multicarrier energy allocation for differentiated QoS provision and dynamic range reduction

Effective energy allocation in a multicarrier communication system for differentiated quality of services (QoS) provision and transmit power dynamic range reduction is investigated in this work. Two different methods are analyzed and compared. The first one is to partition data classes and use their importance weights to develop a multiclass allocation scheme. The second one is to perform a single class allocation scheme at each time slot. A closed-form energy allocation algorithm is developed for fast implementation. The advantage of using multiclass allocation in dynamic range reduction is quantified. This reduction leads to smaller RF output power as well as DC power required by the system. Both theoretical and simulation results are presented in to demonstrate performance
Challenges in cloud based ingest and encoding for high quality streaming media

The Netflix ingest and encoding pipeline is a cloud-based platform that generates video encodes for the Netflix streaming service. Due to the large throughput of the system, automated video quality assessment of the source videos and the generated encodes is essential in ensuring the quality of experience of viewers. This paper discusses the motivations for integrating video quality assessment in the production pipeline, outlines currently deployed solutions and presents the technical challenges in improving the system.
Equation-based layered video multicast with explicit congestion notification

We propose TCP-friendly layered multicast with explicit congestion notification (TFLME) protocol, designed for video streaming to multitude of heterogeneous receivers using IP multicast service. In the design of TFLME protocol, we introduce a congestion control strategy consisting of passive measurement of network congestion and non-integer exponential partition of video layers. The strategy is directly applicable to the layered video format in the standard track like MPEG4-FGS to achieve TCP-friendliness and fairness in presence of TCP-friendly competing traffic, while minimizing the ill effects of the coarse granularity of layer partition commonly found in the typical layered multicast. TFLME protocol utilizes explicit congestion notification (ECN) driven by random early detection (RED) algorithm, which provides advantage in achieving TCP- friendliness with less packet loss. The effectiveness of the proposed strategy and the performance of TFLME protocol are evaluated in the simulation with NS-2 simulator.
Secure and efficient cryptosystem for smart grid using homomorphic encryption

A secure and efficient cryptography-based data exchange scheme for the smart grid based on homomorphic encryption is investigated in this work. Public key cryptography has been proposed as the main tool to ensure the security of a smart grid . We first examine the shortcomings of conventional public key cryptography to motivate our current study. For the uplink communication (i.e. from customers to the utility) in the proposed scheme, smart meters homomorphically encrypt privacy-sensitive customer data before sending them over the grid. To prevent message forgery, a simple authentication scheme is designed specifically for uplink communication. For the downlink communication (i.e. from the utility to customers), the utility transmits the signed control messages to customers using digital signatures to ensure that messages from utilities are not tampered. For the data exchange scheme, we propose a practical cryptosystem based on a partially homomorphic encryption algorithm. The proposed solution has several appealing features such as strengthened security, high efficiency and user privacy preservation.
A graphic approach to performance analysis of multistage linear interference canceller in long-code CDMA systems

The signal-to-interference-plus-noise-ratio performance of the multistage linear parallel and successive interference cancellers (LPIC and LSIC) in a long-code code-division multiple-access system is analyzed using a graphical approach. The decision statistic is modeled as a Gaussian random variable, whose mean and variance can be expressed as functions of moments of R for the LPIC and L for the LSIC, respectively, where R is the correlation matrix of signature sequences and L is the strict lower triangular part of R. Since the complexity of calculating these moments increases rapidly with the growth of the stage index, a graphical representation of moments is developed to facilitate the computation. Propositions are presented to relate the moment calculation problem to several well-known problems in graph theory, i.e., the coloring, the graph decomposition, the biconnected component finding, and the Euler tour problems. It is shown that the derived analytic results match well with simulation results.