超宽带极窄脉冲设计与产生

超宽带(UWB)技术是以持续时间极短的脉冲作为传输载体进行数据通信的无线新技术。基于BJT雪崩特性,本文采用并行同时触发的工作方式,设计并产生了高重复速率的UWB脉冲电路发生器,极大地减少了时延,缩短了上升时间,提高了脉冲的幅度,并从等效电路法的观点分析计算了脉冲的特性参数,理论结果与实测结果具有较好的一致性。     

A New Algorithm for the Elimination of Common Subexpressions in Hardware Implementation of Digital Filters by Using Genetic Programming

A new algorithm based on Genetic Programming (GP) for the problem of optimization of Multiple constant Multiplication (MCM) by Common Subexpression Elimination(CSE) is developed. This method is used for hardware optimization for DSP systems. A solution based on Genetic Programming is shown in this paper. The performance of the technique is demonstrated in one- and multi-dimensional digital filters with constant coefficients.     

Symmetric BEM formulations for 2-D steady-state and transit potential problems

This paper presents a new concept for symmetric boundary element method (SBEM) applicable to 2-D steady-state and transit potential problems. Two kinds of SBEM formulations are derived. Symmetry is obtained simply through matrix manipulation, and no hypersingularity appears. Therefore, SBEM is much easier than the traditional symmetric Galerkin BEM. Compared with the traditional asymmetric BEM, the present SBEM can reduce the computational cost for time domain problems only. However, when applied to BEM/FEM coupling procedure, SBEM can reduce the computational cost for both steady-state and time domain problems. Three numerical examples are included to illustrate the effectiveness and accuracy of the present formulations.     

关于蒸汽疏水器规格尺寸选择的探讨

本文依据疏水器作用原理和实践经验对影响选择疏水器规格尺寸的主要因素进行了分析。提出:选择疏水器应排凝水量大,选择倍率适当,符合产品样本的最大、最小工作压力,准确确定其前后压力。     

3^n阶矩阵乘法的分块算法

针对３＾ｎ阶矩阵的乘法运行，给出了一种分块算法，其乘法运行量比常规的矩阵乘法计算方法和补零的基－２算法都有所减少。     

宁夏汉延渠灌区灌溉水利用系数测算分析与评价

农田灌溉水利用系数表示从水源引水被农作物吸收利用的过程,是反应灌区灌溉用水效率的一项指标。本文以汉延渠灌区为例,综合考虑宁夏的气候环境、土壤类型、灌溉制度及作物种植结构等因素,选取典型渠段和样点灌区,分别采用"连乘法"和"首尾法"计算宁夏汉延渠灌区2018—2019年的灌溉水利用系数,并对其进行对比分析评价,从而确定灌区适宜的计算方法。     

基于CUDA编程模型的稀疏对角矩阵向量乘优化

稀疏矩阵向量乘是很多科学计算问题中的核心问题。本文针对稀疏对角矩阵,在DIA存储格式的基础上,设计了一种新型压缩存储格式CDIA,结合CUDA编程模型的特点,在计算线程上进行了细粒度的任务分配,同时为满足CUDA对存储器的合并访问要求,将压缩矩阵做了相应的转置处理,设计了细粒度算法与程序,并根据稀疏矩阵向量乘特点,做了相应的程序优化。实验数据显示,这种存储格式能够很好地发挥CUDA在数据处理方面的优势,在测试数据中,最高获得了单精度39.6Gflop/s和双精度19.6Gflop/s的浮点计算性能,性能在Nathan Bell和Michael Garland的基础上分别提高了7.6%和17.4%。     

GF(p)上椭圆曲线密码的并行基点选取算法研究*

提出一种GF(p)上椭圆曲线密码系统的并行基点选取算法,该算法由并行随机点产生算法和并行基点判断算法两个子算法组成,给出了算法性能的理论分析和实验结果.结果表明:各并行处理器单元具有较好的负载均衡特性;当执行并行基点判断算法,其标量乘的点加计算时间是点倍数计算时间的三倍时,算法的并行效率可达90%.因此该算法可用于椭圆曲线密码(Elliptic Curve Cryptography,ECC)中基点的快速选取,从而提高ECC的加/解密速度.     

BiELL: A bisection ELLPACK-based storage format for optimizing SpMV on GPUs

Sparse matrix–vector multiplication (SpMV) is one of the most important high level operations for basic linear algebra. Nowadays, the GPU has evolved into a highly parallel coprocessor which is suited to compute-intensive, highly parallel computation. Achieving high performance of SpMV on GPUs is relatively challenging, especially when the matrix has no specific structure. For these general sparse matrices, a new data structure based on the bisection ELLPACK format, BiELL, is designed to realize the load balance better, and thus improve the performance of the SpMV. Besides, based on the same idea of JAD format, the BiJAD format can be obtained. Experimental results on various matrices show that the BiELL and BiJAD formats perform better than other similar formats, especially when the number of non-zero elements per row varies a lot.     

半参数广义线性模型惩罚似然估计的几个性质

本文在给出了半参数广义线性模型惩罚似然估计及惩罚准似然估计的基础上,得到了下面几个性质:(Ⅰ)极小惩罚似然估计及惩罚准似然估计等价于惩罚加权最小二乘估计;(Ⅱ)估计的收敛性及加速收敛法;(Ⅲ)估计的一种 Bayes 解释。