基于Simulink的跳频通信系统同步过程建模与仿真

在Simulink／Matlab环境下建立了含有同步过程的完整跳频通信系统模型。该模型采用了实际跳频通信中常用的同步头和时间信息（TOD）相结合的方法。仿真实验结果表明,该模型能较好模拟跳频系统各部分功能,完整再现跳频系统同步过程,为进一步开展对跳频系统的研究提供了一种有效的平台。     

Position synchronization for track geometry inspection data via big-data fusion and incremental learning

Track geometry inspection data is important for managing railway infrastructure integrity and operational safety. In order to use track geometry inspection data, having accurate and reliable position information is a prerequisite. Due to various issues identified in this research, the positions of different track geometry inspections need to be aligned and synchronized to the same location before being used for track degradation modeling and maintenance planning. This is referred to as “position synchronization”, a long-standing important research problem in the area of track data analytics. With the aim of advancing the state of the art in research on this subject, we propose a novel approach to more accurately and expediently synchronize track geometry inspection positions via big-data fusion and incremental learning algorithms. Distinguishing it from other relevant studies in the literature, our proposed approach can simultaneously address data exceptions, channel offsets and local position offsets between any two inspections. To solve the Position Synchronization Model (PS-Model), an Incremental Learning Algorithm (IL-Algorithm) is developed to handle the “lack of memory” challenge for the fast computation of massive data. A case study is developed based on a dataset with data size of 18 GB, including 58 inspections between February 2014 and July 2016 over 323 km (200 miles) of tracks belonging to China High Speed Railways. The results show that our proposed model performs robustly against data exceptions via the use of multi-channel information fusion. Also, the position synchronization error using our proposed approach is within 0.15 meters (0.5 feet). Our proposed data-driven, incremental learning algorithm can quickly solve the complex, data-extensive, position synchronization problem, using an average of 0.1 s for processing one additional kilometer of track. In general, the data analysis methodology and algorithm presented in this paper are also suitable to address other relevant position synchronization problems in transportation engineering, especially when the dataset contains multiple channels of sensors and abnormal data outliers.     

大鼠附睾上皮内ACP及NSE与过剩精子处理的关系初探

目的　研究大鼠附睾上皮细胞PAS阳性物质的性质 ,以及与溶酶体的酸性水解酶、附睾腔内过剩精子消化处理之间的关系 ,借以阐明附睾上皮处理过剩精子的机制。方法　用组织化学的方法显示PAS阳性物质、非特异性酯酶 (NSE)和酸性磷酸酶 (ACP)并研究其相互关系。结果　PAS阳性颗粒分布于PAS阳性细胞的核下区、核上区或充满整个胞质 ,也可见于附睾管腔内 ,尤其是附睾上皮近腔面 ,呈条带状 ;NSE、ACP阳性颗粒均位于胞质的核上方及附睾上皮的近腔面。结论　NSE、ACP与PAS的染色结果一致 ,说明附睾上皮除吞噬精子外 ,还可能分泌溶酶体酶进入附睾上皮的近腔面以初步处理精子 ,而精子残骸穿过附睾上皮进入间质可能进一步被巨噬细胞系统消化处理     

解不定方程组的新方法

本文讨论了求解一类不定方程组的新方法,其系数矩阵形如其中K和(-H)为正定对称矩阵,应用平方根法分解K=UU~T以及S=UW~T,容易证明R=WW~T-H为正定对称的,进而分解R=VV~T,于是该方法具有平方根法的一切特点.最后对该方法进行了数值误差分析.     

全循环法清渣工艺在钻孔漌注桩施工中的使用心得

“全循环法”实质是将正循环和反循环有机结合、混合使用的一种清渣方法。铁岗中桥桩基础施工实践证明．它改变传统的清渣工艺，是深孔灌注桩（尤其是端承桩）施工中最有效的施工方法之一。     

正线性方程组正解判别的两个结果

非齐次线性方程组在科学计算和日常生活中会经常出现的，在研究实际问题中也会接触系数和右端项皆为正的方程组，而研究它有正解更有实际意义．对正线性方程组给出了合理的变形，对其正解的判别给出了若干方法，得到一些重要结果。     

正项级数敛散性根比判别法

正项级数∞n=1∑un的敛散性判别,一般《数学分析》教材是在介绍了Cauchy准则、比较判别法以后,给出了根值判别、比值判别等方法;本文利用比较判别法,提出了一个全新的、更为一般的判别方法——根比判别法。     

基于双DSP的铁路信号电源监控系统的研究

铁路信号电源是专门给列车运营信号供电的系统,其可靠性要求非常高,因此,对铁路信号电源的监视和控制十分重要,本文在分析现有铁路信号电源存在问题的基础上,探讨了信号电源监控系统的功能需求,并结合数字信号处理器(DSP)的特点,研究了基于双DSP的铁路信号电源监控系统的硬件及功能设计.     

锌银蓄电池研究进展

本文概述了锌银蓄电池的组成、性能,以及锌银蓄电池正极、负极、隔膜技术上的进步,理论上的研究.     

第三代短波自动链路建立系统特性分析

从与第二代ALE技术对比的角度，介绍了第三代短波自动链路建立系统所采用的先进技术，并从链路建立速率方面分析了其有效性，从纠错能力、误码性能等方面分析了其可靠性，同时指出了其相对于第二代技术在系统性能上的改善。