ABC/ADL:一种基于XML的软件体系结构描述语言

作为基于构件的软件开发过程的系统蓝图,软件体系结构(SA)扮演了非常重要的角色,其研究受到越来越多的关注．而软件体系结构描述语言(ADL)是研究和应用SA的基础．提出了一种基于XML的体系结构描述语言——ABC／ADL．ABC／ADL具备大多数ADL描述软件系统高层结构的能力,还支持系统的逐步精化与演化,并支持系统的自动化组装和验证．采用数据互操作标准XML作为元语言,不仅使ABC／ADL具有与其他ADL的互操作性,还有助于实现设计阶段的制品与其他软件生命周期阶段制品之间的可追踪性．     

新型电动自行车调速器的设计

电动自行车作为一种绿色环保型交通工具,越来越受到人们的青睐。本文介绍了电动自行车的一种新型的调速形式—变频调速,并对调速器进行了硬件和软件的设计。     

基于仿真的优化方法综述

针对难以用数学模型表达的优化问题或带有随机性的优化问题,基于仿真的优化方法是其惟一的选择.因此,综述了基于仿真的优化方法的研究情况,介绍了仿真用于策略验证、基于仿真的Genetic Algorithm(GA)、基于仿真的Simulated Annealing(SA)、基于仿真的Particle Swarm Optimization(PSO)和仿真用于获取随机参数或函数等方法的实现.概括了基于仿真的优化方法在各领域的应用,并结合国内外的研究情况,对基于仿真的优化方法的难点进行了总结,并对其发展方向作了分析.     

基于压缩后缀数组技术的搜索引擎

目前,搜索引擎的核心模块(索引器)均采用倒排文件结构,对短语查询的准确率较低。该文引入后缀数组技术进行全文索引,为克服全文索引时占用空间大的缺点,研究了压缩后缀数组技术,把后缀数组索引的大小压缩到了O(n)位,并给出应用压缩后缀数组索引的步骤和核心操作伪代码。对比实验表明,基于压缩后缀数组的索引比传统倒排文件索引的短语查准率提高了近20%。     

Network aspects of integrating 5G and satellite communication

Since 2017, 3rd Generation Partnership Program (3GPP) is working on integration of satellite communication in 3GPP. This paper discusses the results of the work on service and network architecture aspects in 3GPP Technical Specification Group (TSG) Service and System Aspects (SA) and 3GPP TSG Core Networks and Terminals (CT). This paper does not discuss radio aspects as are specified in 3GPP TSG radio access network (RAN). 3GPP first specified requirements and use cases for satellite access. Subsequently, architecture and protocol specifications were created for integration scenarios, direct access, network selection, mobility management, and satellite backhaul with quality of service (QoS). Also, impacts of regulatory aspects on satellite integration have been discussed in 3GPP. With the completion of Release 17, 3GPP specifications are now ready for implementation of integrated 5G satellite networks. 3GPP will continue with further development of satellite integration in Release 18 and Release 19.     

GPS接收机用于两点间精密测距方法的研究

本文叙述了采用两台ＧＰＳ接收机实现两点间精密测距的方法，其测距误差绝对值小于１ｍ。当给定一个基准点后该方法也可推广应用于精密一。文中不仅给出了测距系统的构成方案及实现精密测距挨处理算法，而且给出了激光测距仪和该ＧＰＳ测距系统的测距结果比较。     

SA516—70钢的焊接裂纹

分析了ＳＡ５１６－７０钢ＳＡＷ时横向裂纹和纵向裂纹产生的机理，提出了防止裂纹的工艺措施。     

Joint channel estimation and data detection for high rate orthogonal time frequency space systems

This paper proposes a new pilot pattern in the delay-Doppler (DD) domain for the orthogonal time frequency space (OTFS) system. In contrast to the embedded-pilot schemes, guard intervals are not used so as increase the spectral efficiency. Also, compared to the superimposed design where data symbols and pilots are arranged on the entire DD grid, in the proposed rearrangement, the number of pilots used is only spread over a subgrid of the DD grid. Hence, the interference of pilots with data symbols is reduced. Afterwards, an algorithm for channel estimation (CE) and symbol detection in the DD domain benefiting from the sparsity of the DD channel is designed. The sparse CE step is formulated as a specific marginalization of the maximum a posteriori (MAP) criterion by providing a Bayesian approach via the mean-field approximation that involves the variational Bayesian expectation maximization (VB-EM) algorithm. Detection of data symbols is done using a low complexity MP algorithm. We also propose an interference cancellation (IC) scheme to mitigate contamination of data by pilots that is run after each CE step. To achieve a high CE accuracy, based on the mean mutual incoherence property (MIP), a pilot optimization problem for OTFS is formulated and develop a simulated annealing-based algorithm to solve it. Finally, simulation results show that the proposed scheme achieves a good compromise between spectral efficiency, complexity, and performance in terms of bit error rate (BER) and normalized mean square error (NMSE) when compared to literature benchmarks.     

SA508-3钢回火焊道技术焊道搭接量的分析

针对核电设备常用钢种SA508-3钢,采用钨极氩弧自动焊接方法,对该钢种在使用回火焊道焊接技术修复时的焊道搭接量进行了分析。试验结果表明,焊道搭接量在0%~30%时,相邻的焊道间有明显的凹坑的存在,在后续焊道的焊接过程中容易出现未熔合问题;焊道搭接量达到70%时,焊道表面向瘤状发展,不利于后续焊道的排布,焊道几何尺寸的排布使得回火焊道焊接技术无法实施;焊道搭接量在40%~60%时,焊道分布相对平直,显微硬度及淬硬组织分布均匀,利于回火焊道技术的实施。     

基于SA9604的多功能电能表

介绍了一种以SA9604为计量芯片的多功能电表，并给出功能框图和工作原理，同时给出计算机自动校表的原理和修正公式。