Low-complexity concatenated two-state TCM schemes with near-capacity performance

This paper presents a family of concatenated two-state trellis-coded modulation (CT-TCM) schemes. Compared with the existing turbo-type bandwidth-efficient coded modulation schemes, the proposed codes have significantly reduced complexity without sacrificing performance. A joint design strategy for all component codes is established. This leads to so-called asymmetrical and time-varying trellis structures, which possess good Hamming and Euclidean distance distributions. The performance of the proposed codes is demonstrated by simulation results.     

Fractional-order anisotropic diffusion for image denoising.

This paper introduces a new class of fractional-order anisotropic diffusion equations for noise removal. These equations are Euler-Lagrange equations of a cost functional which is an increasing function of the absolute value of the fractional derivative of the image intensity function, so the proposed equations can be seen as generalizations of second-order and fourth-order anisotropic diffusion equations. We use the discrete Fourier transform to implement the numerical algorithm and give an iterative scheme in the frequency domain. It is one important aspect of the algorithm that it considers the input image as a periodic image. To overcome this problem, we use a folded algorithm by extending the image symmetrically about its borders. Finally, we list various numerical results on denoising real images. Experiments show that the proposed fractional-order anisotropic diffusion equations yield good visual effects and better signal-to-noise ratio.     

Mobile Vehicle-to-Vehicle Narrow-Band Channel Measurement and Characterization of the 5.9 GHz Dedicated Short Range Communication (DSRC) Frequency Band

This study presents narrow-band measurements of the mobile vehicle-to-vehicle propagation channel at 5.9 GHz, under realistic suburban driving conditions in Pittsburgh, Pennsylvania. Our system includes differential Global Positioning System (DGPS) receivers, thereby enabling dynamic measurements of how large-scale path loss, Doppler spectrum, and coherence time depend on vehicle location and separation. A Nakagami distribution is used for describing the fading statistics. The speed-separation diagram is introduced as a new tool for analyzing and understanding the vehicle-to-vehicle propagation environment. We show that this diagram can be used to model and predict channel Doppler spread and coherence time using vehicle speed and separation.     

细菌柱浸铀矿工艺过程中钍浸出特征 试验研究

以721铀矿云际矿石为研究对象,通过室内铀矿石柱浸试验,研究铀矿石在细菌池浸过程中钍浸出特征。试验结果表明,柱浸过程中,水文地球化学条件(pH和Eh)对钍浸出影响不大,随着时间变化,pH值在1.73¹.36发生变化,Eh值在1691.36发生变化,Eh值在169⁵92mV变化,但钍浸出量基本稳定在2.2592mV变化,但钍浸出量基本稳定在2.2².5mg/L。同时试验结果发现,原矿铀浸出率为80.03%,钍浸出率仅约为14.1%,主要原因是U、Th的化学性质不同,Th均以+4价稳定存在于矿石中,一般不易被溶解而迁移转化。U具有多种价态,在氧化条件下显示+6价,而这种价态的U性质活泼,易于在环境中迁移转化。     

岩土工程勘察设计常见问题与解决对策

勘察数据的准确性关乎建筑架构的稳定性及后期运营周期.分析了目前在岩土勘察设计上的不足之处,分别从技术、管理及人员3个层面来展开,并且列举实例进行分析,从滑动面、物探、电法勘探以及钻探等方面进行研究,提出解决问题的对策,可为类似工程提供借鉴.     

硫化氢光催化分解制氢

重点阐述了在半导体催化剂作用下,光催化分解硫化氢制氢工艺的催化机理、催化剂的设计与制备方法以及光催化分解硫化氢制氢的工艺过程.     

国产马丁式垃圾焚烧炉系统设计中的若干问题

主要从已建成投产的城市生活垃圾焚烧发电厂的垃圾焚烧系统所出现的典型问题进行讨论,为国内垃圾焚烧炉系统的设计工作者提供参考。     

从专利看航空喷气公司发展历程及其高超声速核心技术

采用专利定量分析和定性分析手段,结合其它情报分析方法,以美国发动机领域的顶尖企业航空喷气公司（Aerojet）1946—2014年3月期间公开专利为主要研究对象,分析了其发展历程及其在高超声速领域的核心技术。通过专利分析,展现了其经历成长期、快速增长期、投资多元化期、衰退期到复兴期的公司发展历程,并研究了航空喷气公司在高超声速领域的中心燃烧技术、先进组合循环整合进气道技术和气动阻塞技术及其优势,最后给出了在管理和技术方面的启示。     

基于NTP 的航天测控网络对时系统

为了保证航天系统内时间的准确性和一致性,设计一种基于网络时间协议(network time protoco,NTP)的航天测控网络对时系统。针对各系统设备对时间的精确性和可靠性要求,在分析NTP基本原理和工作模式的基础上,建立了航天测控网络上的NTP对时系统架构,根据具体应用编程实现了NTP网络对时系统,并对该系统是否满足航天测控网络对时间精度的要求进行验证。实践结果证明:该系统能把全网中的用户设备时间偏差精度控制在1 ms以内,实现高精度的对时。     

小型定向引信探测器研究

就应用于定向战斗部的小型定向引信探测器展开研究，给出了定向探测方案，设计了定向引信探测器的射频前端电路，利用Ansoft Designer软件对射频收发系统进行了建模仿真，并把MMIC及组件混合集成技术应用于引信系统，实现了定向引信的小型化．测试结果证明了定向引信探测器小型化方案的可行性．