直和码的广义Hamming重量

当 A是特殊的 (n,1,n)等重码和 (n,n,1)等重等距码时 ,通过对两个旧码 A和 B构造一个新码 A B即直和码的分析 ,给出了 A B广义 Ham ming重量与 A、B的广义 Ham ming重量的关系 ;在 A、B是一般情形下 ,对直和码的广义 Ham ming重量进行了研究。

和码输入技术中字根编码的建构研究

30年前,英文输入计算机轻松自如,汉字输入却困难重重。自王永明于1986年发明了汉字输入技术———五笔字型以来,使用该技术输入汉字最快速度可以达到每分钟250个汉字。2004年,欧阳贵林发明了计算机和手机统一通用的汉字输入技术———和码[1]。

加权和码辅助的极化码SCL译码算法

为了进一步降低极化码串行抵消列表译码算法的译码时延,提出了一种加权和码辅助的串行抵消列表译码算法。采用加权和码级联极化码的编码方案,将加权和码产生的校验比特与信息序列一同输入极化码编码器进行极化码编码。加权和码辅助的串行抵消列表译码算法是在原始的串行抵消列表译码后,使用加权和码对候选路径依次校验,选择置信度最高且通过校验的路径作为译码输出。与广泛应用的循环冗余校验码相比,加权和码有一致的检错性能,并且其编译码硬件实现的时延低。仿真结果表明,加权和码辅助的串行抵消列表译码算法与循环冗余校验码辅助的串行抵消列表译码算法相比较,性能曲线基本重合,且在很大程度上降低了译码的校验时延。

汉字编码设计的基本问题与和码方案的特点分析

以汉字形码编码方案设计的四个基本问题为线索,通过比较,分析和码汉字数字方案的三个主 要的创新技术,即:采用25个数字输入码;25个输入码采用二维排序,第二维按部件对字义与字结构的限 定性大小排序;以及取码方法采用在定点和剩余部份取最大码值的码。说明和码汉字输入码编码方案达到 了汉字输入的简单易记,低重码率,规范和统一(通用)的目的。

基于字根的“机写”汉字学习法

汉字教学效率低，汉字字形“难学难用”是普遍存在于我国语文教育与对外汉语教学中的现象。本文通过对汉字字形教学中几个问题的分析，指出字根是分析理解、识记汉字的基础，学好汉字的关键是练习使用汉字。在信息时代，汉字字形输入（键盘写字）是练习使用汉字字形的最好方法，在教学中采用并强调汉字字根分析与字形输入，可提高字形教学效率。这种方法可以作为拼音输入法的补充，并可以克服拼音输入法导致的“汉字失写症”的弊病。本文主要介绍了基于字根的和码机写汉字学习法的主要内容。

Several Classes of Two-weight or Three-weight Linear Codes and Their Applications

Recently,linear codes with a few weights have been extensively studied due to their applications in secret sharing schemes,constant composition codes,strongly regular graphs and so on.In this paper,based on the Weil sums,several classes of two-weight or three-weight linear codes are presented by choosing a proper defining set,and their weight enumerators and complete weight enumerators are determined.Furthermore,these codes are proven to be minimal.By puncturing these linear codes,two classes of two-weight projective codes are obtained,and the parameters of the corresponding strongly regular graph are given.This paper generalizes the results of[7].

Low-dose CT image denoising method based on generative adversarial network

In order to solve the problems of artifacts and noise in low-dose computed tomography(CT)images in clinical medical diagnosis,an improved image denoising algorithm under the architecture of generative adversarial network(GAN)was proposed.First,a noise model based on style GAN2 was constructed to estimate the real noise distribution,and the noise information similar to the real noise distribution was generated as the experimental noise data set.Then,a network model with encoder-decoder architecture as the core based on GAN idea was constructed,and the network model was trained with the generated noise data set until it reached the optimal value.Finally,the noise and artifacts in low-dose CT images could be removed by inputting low-dose CT images into the denoising network.The experimental results showed that the constructed network model based on GAN architecture improved the utilization rate of noise feature information and the stability of network training,removed image noise and artifacts,and reconstructed image with rich texture and realistic visual effect.

辅助北斗技术的捕获空间计算和误差分析

结合辅助北斗定位技术的辅助信息类型,提出了北斗GEO和NGEO卫星在星历辅助条件下的卫星信号载波频率和码相位的估计方法,在此基础上重点研究了估计得到的载波频率和码相位的不确定度,并针对粗时间和精时间这两种典型的辅助定位技术进行了算例分析。研究结果表明:粗时和精时辅助能有效减少捕获搜索空间;引起载波频率搜索范围不确定度的因素是时钟频偏和接收机动态,而引起码相位搜索范围不确定度的因素是辅助时间精度和辅助位置误差。

Non-iterative image feature matching algorithm based on reference point correspondences

Based on the coded and non-coded targets, the targets are extracted from the images according to their size, shape and intensity etc., and thus an improved method to identify the unique identity（D） of every coded target is put forward and the non-coded and coded targets are classified. Moreover, the gray scale centroid algorithm is applied to obtain the subpixel location of both uncoded and coded targets. The initial matching of the uncoded target correspondences between an image pair is established according to similarity and compatibility, which are based on the ID correspondences of the coded targets. The outliers in the initial matching of the uncoded target are eliminated according to three rules to finally obtain the uncoded target correspondences. Practical examples show that the algorithm is rapid, robust and is of high precision and matching ratio.

Low complexity joint source-channel decoding for transmission of wavelet compressed images

To utilize residual redundancy to reduce the error induced by fading channels and decrease the complexity of the field model to describe the probability structure for residual redundancy, a simplified statistical model for residual redundancy and a low complexity joint source-channel decoding（JSCD） algorithm are proposed. The complicated residual redundancy in wavelet compressed images is decomposed into several independent 1-D probability check equations composed of Markov chains and it is regarded as a natural channel code with a structure similar to the low density parity check （LDPC） code. A parallel sum-product （SP） and iterative JSCD algorithm is proposed. Simulation results show that the proposed JSCD algorithm can make full use of residual redundancy in different directions to correct errors and improve the peak signal noise ratio （PSNR） of the reconstructed image and reduce the complexity and delay of JSCD. The performance of JSCD is more robust than the traditional separated encoding system with arithmetic coding in the same data rate.

Optimization design of 24bit parallel MAC unit with saturation

An efficient design method for a 24 × 24 bit ＋48 bit parallel saturating multiply-accumulate （MAC） unit is described. The augend in the MAC is merged as a partial product into Wallace tree array. The optimized saturation detection logic is proposed. The 679. 2 μm × 132. 5μm area size has been achieved in 0. 18 μm 1.8 V 1P6M CMOS technology by the full-custom circuit layout design. The simulation results show that the design way has significantly less area （about 23.52% reduction） and less delay than those of the common saturating MAC based on standard cell library.

ALL ZERO MACROBLOCK DECISION METHOD FOR H.26L

In order to reduce the computation in the part of motion search and transform in H.26L encoder, an all-zero macroblock decision method based on integer transform and motion search is proposed in this paper. According to the characteristics of integer transform and motion search in H.26L, all-zero macroblock decision is made in inter frame coding by comparing Sum of the Absolute Differences(SAD) with a value related with Quantization Parameter(QP)before integer transform. It avoids a large amount of computation in motion search, transform and quantization. This technology highly improves the efficiency of real time H.26L encoder by skipping all-zero macroblock before integer transform and shortening the code stream at the same time.

High-efficiency Gaussian key reconciliation in continuous variable quantum key distribution

Efficient reconciliation is a crucial step in continuous variable quantum key distribution. The progressive-edge-growth(PEG) algorithm is an efficient method to construct relatively short block length low-density parity-check(LDPC) codes. The qua-sicyclic construction method can extend short block length codes and further eliminate the shortest cycle. In this paper, by combining the PEG algorithm and quasi-cyclic construction method, we design long block length irregular LDPC codes with high error-correcting capacity. Based on these LDPC codes, we achieve high-efficiency Gaussian key reconciliation with slice recon-ciliation based on multilevel coding/multistage decoding with an efficiency of 93.7%.

1-GENERATOR QUASI-CYCLIC CODES

This paper discusses the enumeration of 1-generator quasi-cyclic codes and describes an algorithm which will obtain one, and only one, generator for each 1-generator quasi-cyclic code.

On Reed-Solomon Codes

The complexity of decoding the standard Reed-Solomon code is a well-known open problem in coding theory.The main problem is to compute the error distance of a received word.Using the Weil bound for character sum estimate,Li and Wan showed that the error distance can be determined when the degree of the received word as a polynomial is small.In the first part,the result of Li and Wan is improved.On the other hand,one of the important parameters of an error-correcting code is the dimension.In most cases,one can only get bounds for the dimension.In the second part,a formula for the dimension of the generalized trace Reed-Solomon codes in some cases is obtained.

An improved low-complexity sum-product decoding algorithm for low-density parity-check codes

In this paper, an improved low-complexity sum-product decoding algorithm is presented for low-density parity-check （LDPC） codes. In the proposed algorithm, reduction in computational complexity is achieved by utilizing fast Fourier transform （FFT） with time shift in the check node process. The improvement in the decoding performance is achieved by utilizing an op- timized integer constant in the variable node process. Simulation results show that the proposed algorithm achieves an overall coding gain improvement ranging from 0.04 to 0.46 dB. Moreover, when compared with the sum-product algorithm （SPA）, the proposed decoding algorithm can achieve a reduction of 42%-67% of the total number of arithmetic operations required for the decoding process.

The Gauss sums and Jacobi sums over Galois ring GR(p^2 , r)

Galois rings and exponential sums over Galois rings have many applications in algebraic combinatorics, coding theory and cryptography. In this paper, we present explicit description on the Gauss sums and Jacobi sums over Galois ring GR(p2 , r), and show that the values of these sums can be reduced to the Gauss sums and Jacobi sums over finite field Fpr for all non-trivial cases.

Improved multiparty quantum key agreement in travelling mode

The need to simultaneously balance security and fairness in quantum key agreement(QKA) makes it challenging to design a flawless QKA protocol, especially a multiparty quantum key agreement(MQKA) protocol. When designing an MQKA protocol,two modes can be used to transmit the quantum information carriers: travelling mode and distributed mode. MQKA protocols usually have a higher qubit efficiency in travelling mode than in distributed mode. Thus, several travelling mode MQKA protocols have been proposed. However, almost all of these are vulnerable to collusion attacks from internal betrayers. This paper proposes an improved MQKA protocol that operates in travelling mode with Einstein-Podolsky-Rosen pairs. More importantly, we present a new travelling mode MQKA protocol that uses single photons, which is more feasible than previous methods under current technologies.

A computational fluid dynamics model for wind simulation:model implementation and experimental validation

To provide physically based wind modelling for wind erosion research at regional scale, a 3D computational fluid dynamics (CFD) wind model was developed. The model was programmed in C language based on the Navier-Stokes equations, and it is freely available as open source. Integrated with the spatial analysis and modelling tool (SAMT), the wind model has convenient input preparation and powerful output visualization. To validate the wind model, a series of experiments was con- ducted in a wind tunnel. A blocking inflow experiment was designed to test the performance of the model on simulation of basic fluid processes. A round obstacle experiment was designed to check if the model could simulate the influences of the obstacle on wind field. Results show that measured and simulated wind fields have high correlations, and the wind model can simulate both the basic processes of the wind and the influences of the obstacle on the wind field. These results show the high reliability of the wind model. A digital elevation model (DEM) of an area (3800 m long and 1700 m wide) in the Xilingele grassland in Inner Mongolia (autonomous region, China) was applied to the model, and a 3D wind field has been successfully generated. The clear imple- mentation of the model and the adequate validation by wind tunnel experiments laid a solid foundation for the prediction and assessment of wind erosion at regional scale.