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Discharge regularity in the turtle posterior crista: comparisons between experiment and theory

JOURNAL OF NEUROPHYSIOLOGY 2013年第12期110卷 2830-2848页

作者： Goldberg, Jay M. Holt, Joseph C. Univ Chicago Dept Pharmacol & Physiol Sci Chicago IL 60637 USA

Intra-axonal recordings were made from bouton fibers near their termination in the turtle posterior crista. Spike discharge, miniature excitatory postsynaptic potentials (mEPSPs), and afterhyperpolarizations (AHPs) were monitored during resting activity in both regularly and irregularly discharging units. Quantal size (qsize) and quantal rate (qrate) were estimated by shot-noise theory. Theoretically, the ratio, sigma(V)/(d mu(V)/dt), between synaptic noise (sigma(V)) and the slope of the mean voltage trajectory (d mu(V)/dt) near threshold crossing should determine discharge regularity. AHPs are deeper and more prolonged in regular units;as a result, d mu(V)/dt is larger, the more regular the discharge. The qsize is larger and qrate smaller in irregular units;these oppositely directed trends lead to little variation in sigma(V) with discharge regularity. Of the two variables, d mu(V)/dt is much more influential than the nearly constant sigma(V) in determining regularity. Sinusoidal canal-duct indentations at 0.3 Hz led to modulations in spike discharge and synaptic voltage. Gain, the ratio between the amplitudes of the two modulations, and phase leads re indentation of both modulations are larger in irregular units. Gain variations parallel the sensitivity of the postsynaptic spike encoder, the set of conductances that converts synaptic input into spike discharge. Phase variations reflect both synaptic inputs to the encoder and postsynaptic processes. Experimental data were interpreted using a stochastic integrate-and-fire model. Advantages of an irregular discharge include an enhanced encoder gain and the prevention of nonlinear phase locking. Regular and irregular units are more efficient, respectively, in the encoding of low-and high-frequency head rotations, respectively.

关键词： discharge regularity miniature excitatory postsynaptic potentials afterhyperpolarizations integrate-and-fire model coding efficiency

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Using scene-change detection and multiple-thread background memory for efficient video coding

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ELECTRONICS LETTERS 1999年第4期35卷 290-291页

作者： Zhang, K Kittler, J Univ Surrey Sch EEIT&M CVSSP Guildford GU2 5XH Surrey England

The use of background memory to improve coding efficiency has gained momentum recently due to the rapid decrease in the cost of memory chips. However, the associated computational costs still pose a problem for real time implementation. The authors propose a coding oriented scene-change detection algorithm and the use of multiple thread background memory to improve the coding efficiency of both scene-change frames and frames between two consecutive scene cuts. The experimental results show that the proposed scheme can improve the coding efficiency in both situations. The improvement is significant for scene-change frames.

关键词： coding efficiency Image and video coding Digital storage Video signal processing real time implementation scene-change frames digital storage real-time systems scene-change detection video coding multiple-thread background memory

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Factorisation for subclass of symmetric-antisymmetric multifilter banks and its application to image coding

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ELECTRONICS LETTERS 2000年第6期36卷 516-518页

作者： Gao, XQ Gan, L Zou, CR Southeast Univ Dept Radio Engn Nanjing 210096 Peoples R China

A complete and minimal factorisation is proposed for an important subclass of symmetric-antisymmetric multiwavelet filter banks (SAMFBs). Based on this factorisation, optimal SAMFBs are designed for image coding under an optimisation criterion. Experimental results show that the SAMFBs significantly outperform the traditional 9-7 wavelet in terms of coding efficiency, especially for hard-to-compress images.

关键词： optimisation symmetric-antisymmetric multifilter banks coding efficiency filtering theory Image and video coding data compression hard-to-compress images Filtering methods in signal processing Optimisation techniques optimisation criterion image coding minimal factorisation zerotree image coder multiwavelet filter banks Signal processing theory image coding application Computer vision and image processing techniques

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Multiple length adaptive windowing of audio signals

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ELECTRONICS LETTERS 1999年第14期35卷 1133-1135页

作者： Vanelli-Coralli, A Corazza, GE Orsini, A Univ Bologna Dept Elect Comp Sci & Syst I-40136 Bologna Italy

Audio coders generally operate on a per-frame basis to tackle signal non-stationarity. The choice of frame length is crucial to system performance since it trades off coding efficiency and pre-echo avoidance. A new algorithm based on multiple length adaptive windowing is proposed as an enhanced front-end for audio coders. Overhead reductions in excess of 40% are reported.

关键词： audio signals coding efficiency audio coding frame length multiple length adaptive windowing overhead reductions enhanced front-end pre-echo avoidance audio coders Speech and audio coding system performance adaptive signal processing signal nonstationarity

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Identification of T-codes with minimal average synchronisation delay

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IEE PROCEEDINGS-COMPUTERS AND DIGITAL TECHNIQUES 2000年第4期147卷 237-240页

作者： Fong, ACM Higgie, GR Nanyang Technol Univ Sch Appl Sci Singapore 639798 Singapore Univ Auckland Dept Elect & Elect Engn Auckland 1 New Zealand

When T-codes are used to encode an information source most efficiently, their tendency towards self-synchronisation is among the strongest. The best T-codes achieve self-synchronisation within 1.5 characters following a lock loss. Attempts have been made to build databases of the best T-codes, These rely on the comparison of average synchronisation delay (ASD) values that have to be determined using complex algorithms. Criteria are proposed for selecting T-code sets that have intrinsically low ASD values. These criteria are derived from the underlying synchronisation process of T-codes based on the T-code construction algorithm. This latest contribution means that T-codes that are optimal, in terms of both coding efficiency and synchronisation performance, can be found for any given information source more easily compared to previous methods.

关键词： average synchronisation delay information source variable length codes encoding T-codes identification coding efficiency minimal average synchronisation delay Codes delays self-synchronisation Information theory

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Multi-Band Transmission Using Reconfigurable Complex Multi-Band Delta Sigma Polar Modulator

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS 2022年第1期69卷 94-98页

作者： Kumar, Nishant Rawat, Karun Ghannouchi, Fadhel M. Indian Inst Technol Roorkee Dept Elect & Commun Roorkee 247667 Uttar Pradesh India Univ Calgary iRadio Lab Dept Elect & Comp Engn Schulich Sch Engn Calgary AB T2N 1N4 Canada

This brief presents a new reconfigurable complex multi-band delta sigma polar modulator (CMB-DSPM) architecture for multi-band transmission. In this brief, a 6th order band-pass delta sigma modulator (DSM) is designed and implemented for reconfigurable triple-band transmission. The proposed DSM architecture utilizes the advantage of a complex DSM structure to reduce the required processing block and polar quantizer to reduce the quantization noise. The proposed CMB-DSPM architecture improves the in-band and out-of-band performance in terms of signal-to-noise distortion ratio (SNDR) and coding efficiency (CE), respectively. The proposed scheme is validated in MATLAB/SIMULINK-based digital signal processing platform using three 5 MHz long-term evolution (LTE) signals. The results show up to 12.4 dB improvement in SNDR and 12.3% improvement in CE compared to the standard cartesian DSM architecture. The measured EVM is below 3%, which shows the good in-band performance of the proposed scheme.

关键词： Carrier aggregation coding efficiency delta Sigma modulation multi-band transmission polar quantization

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RNS-based implementation of 8x8 point 2D-DCT over field-programmable devices

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ELECTRONICS LETTERS 2003年第1期39卷 21-23页

作者： Fernández, PG Lloris, A Dept Electron & Tecnol Computadores Granada 18071 Spain

A new implementation of an 8 x 8 two-dimensional discrete cosine transform (2D-DCT) processor based on the residue number system (RNS) is presented. This architecture makes use of a fast cosine transform algorithm. It is shown that the RNS implementation of the 2D-DCT over field-programmable logic devices leads to a 129% throughput improvement over the equivalent binary system.

关键词： residue number systems discrete cosine transforms image coding data compression pipeline arithmetic field programmable gate arrays RNS-based implementation 2D-DCT image compression coding efficiency pipelined architecture field-programmabl Image compression discrete cosine transforms residue number systems image coding pipeline arithmetic Field programmable gate arrays Data compression code efficiency

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Efficient intra-mode decision algorithm skipping unnecessary depth-modelling modes in 3D-HEVC

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ELECTRONICS LETTERS 2015年第10期51卷 756-757页

作者： Park, Chun-Su Sejong Univ Seoul South Korea

The three-dimensional (3D) extension of the high-efficiency video coding (3D-HEVC) standard adopts new depth-modelling modes (DMMs) to provide an alternative prediction scheme for depth-map intra-coding. In 3D-HEVC, although edges in depth maps can be accurately estimated by utilising the DMMs, testing the DMMs in the mode decision introduces a huge computational load to the encoder. A fast mode decision algorithm is proposed that can significantly reduce the computational overhead incurred by the DMMs. Experimental results indicate that the proposed algorithm reduces the encoding complexity by 33.89% on average without any penalty in coding efficiency.

关键词： video coding 3D extension 3D-HEVC DMM coding efficiency computational overhead reduction depth-map intra-coding depth-modelling modes efficient intramode decision algorithm encoding complexity fast-mode decision algorithm high-efficiency video coding standard prediction scheme three-dimensional extension

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A Predictive Block Based DC Offset for H.264/AVC Video coding

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2010年第5期E93A卷 976-980页

作者： Jia, Jie Yoon, Daeil Kim, Hae Kwang Sejong Univ Dept Comp Sci & Engn Seoul 143747 South Korea

Video coding standard H.264/AVC employs transform coding to explore spatial correlation in inter picture prediction residue. This paper presents a block based DC offset to further explore the correlation in spatially neighboring blocks and provides H.264/AVC an enhanced coding efficiency performance. The proposed method applies DC offset to inter picture prediction residue, and encodes the offset compensated residual signal. The DC offset is derived from reconstructed residue in neighboring blocks. No additional bits are required for the DC offset representation. Simulation results report that the proposed method yields an average of 2.67% bit rate reduction for high resolution video over the H.264 baseline profile.

关键词： video compression DC offset coding efficiency H.264/AVC

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Very large-scale integration architecture for wavelet-based ECG signal adaptive coder

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IET SIGNAL PROCESSING 2019年第1期13卷 56-64页

作者： Kumari, Ramapackiam Shantha Selva Rajalakshmi, Elaiyaperumal Mepco Schlenk Engn Coll Dept Elect & Commun Engn Sivakasi India

Very large scale integration architecture for the blocks in the novel algorithm with parallel processing is proposed. It increases the performance of the proposed coder. Since the mean is removed from electrocardiogram (ECG) signal it is represented by less number of bits. The lifting scheme-based Haar wavelet transform with five levels decomposition is used to decompose the mean removed ECG signal. One sub-band of approximation coefficient (A(5)) and five sub-bands of detailed coefficients (D-5, D-4, D-3, D-2 and D-1) are obtained. Each sub-band is represented by the corresponding number of bits by using adaptive encoder. The converted bits are transmitted through the channel using a compact format. The coding efficiency shows that the proposed coder outperforms than other coders such as novel algorithm, Djohn, Alshamali, EZW, Benzid, Chan, Khaldi, Gurkan, Wang and Set Partitioning In Hierarchical Trees (SPIHT). The proposed coder is tested on the MIT-BIH arrhythmia database (48 records) and the MIT-BIH ECG compression test database (two records) and its performance is evaluated by using evaluation metrics such as compression ratio (CR) and per cent root mean square difference (PRD). For MIT-BIH arrhythmia database record 117, a CR of 9.132:1 is achieved by the proposed coder with PRD 1.2274%.

关键词： wavelet transforms medical signal processing adaptive codes electrocardiography encoding data compression parallel processing MIT-BIH ECG compression test database wavelet-based ECG signal adaptive coder wavelet-based adaptive coding algorithm parallel processing lifting scheme-based Haar wavelet transform coding efficiency MIT-BIH arrhythmia database record percent root mean-square difference compression ratio

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