加强无线电管理,日常监督检查势在必行

随着社会经济的迅速发展,无线电通信事业取得了很大进步,无线电通信广泛应用于各行各业,在经济发展、社会进步中发挥了重要的作用.但目前一些单位和个人无视国家有关频率管理和无线电设备管理的有关法规,擅自占用频率和非法设台情况比较严重,极大地损害了电磁环境和秩序,干扰了航空导航、公安、消防、护林防火、“三防”等重要通信业务,对无线电通信的可持续性发展造成了极大隐患,加强无线电管理日常监督检查势在必行.     

MIMO系统的自适应均衡技术研究

研究了用于MIMO系统的自适应均衡的几种算法，比较了最小均方算法(LMS)、递归最小二乘算法(RLS)、判决反馈算法(DFE)、格型梯度自适应均衡算法(GALE)和格型最小二乘自适应均衡算法(LSALE)。文章的最后给出了仿真结果及结论。     

The Effects of Filtered Channel Quality Feedback on Throughput of Proportional Fair Algorithm

1　IntroductionSchedulingalgorithmsarewidelystudiedforwirelesspacketdatasystems,whichgenerallyhavetwobasiccategories,oneisoptimizedforsystemthroughputandfairness[1～ 2 ] ,andtheotherisforthequalityofservice[3～6] .Forsystemswherepack etdataaretimedivisionmultiplexedacrossusersonthedownlink ,orfromBaseStation (BS)tomultipleMobileStations(MS) ,theBSusesschedulingalgo rithmstodecidewhichuseristransmittedto .ItisindicatedinRefs.[7,8]thatschedulingonlyoneus eratatimeisoptimalfromthepointofviewo…     

一种数字语音通信系统的DSP实现

介绍了一种甚低频低码率数字通信系统的实现方案，该方案中的软件采用混合编程的方法，硬件则用DSP实现，文章给出了整个系统的DSP软硬件调试方法，并通过调试结果表明该方案具有很好的可行性和实时性。     

Field emission mechanism from nanocrystalline cubic boron nitride films

An electron-emission theoretical model integrating the change in the grain size of nanocrystalline cubic boron nitride (c-BN) thin films was established. To understand better the essence of field emission, an accurate numerical scheme, the transfer matrix method, that can be used to compute the tunneling coefficients of the actual surface barrier, was also adopted. The present results show that the emission current from nanocrystalline grain films is far larger than that from regular grain films or bulk c-BN.     

Distributed Rule-Regulated Spectrum Sharing

Dynamic spectrum access is a promising technique to use spectrum efficiently. Without being restricted to any prefixed spectrum bands, nodes choose operating spectrum on-demand. Such flexibility, however, makes efficient and fair spectrum access in large-scale networks a great challenge. Prior work in this area focused on explicit coordination where nodes communicate with peers to modify local spectrum allocation, and may heavily stress the communication resource. In this paper, we introduce a distributed spectrum management architecture where nodes share spectrum resource fairly by making independent actions following spectrum rules. We present five spectrum rules to regulate node behavior and maximize system fairness and spectrum utilization, and analyze the associated complexity and overhead. We show analytically and experimentally that the proposed rule-based approach achieves similar performance with the explicit coordination approach, while significantly reducing communication cost.     

提高自主创新能力，加速变频器制造业持续快速发展

创新是企业发展不竭的动力，是增强企业竞争力的关键因素。本文就变频器企业在当前激烈的市场矗虿中，如何做好自主创新工作进行了探讨。在简要阐述自主创新的重要意义后，分析了变频器企业目前发展的现状和存在的问题。针对问题提出了变频器企业在开展自主创新时，可供参考的一些基本思路和途径。     

Synthesis, morphology and random laser action of ZnO nanostructures

Three-dimensional (3-D) ZnO random-wall nanostructures and one-dimensional (1-D) ZnO nanorods were prepared on silicon substrates by a simple solid-vapour phase thermal sublimation technique. Optical pumped random lasing has been observed in the ZnO random-wall arrays with a threshold intensity of 0.38 MW/cm² in the emission wavelength from 380 to 395 nm. The optical gain was attributed to the closed-loop scattering and light amplification of the ZnO random-wall. The experimental result suggests that the morphology of nanostructure is the key factor to effect random lasing.     

Photocatalytic Synthesis of Oxygenates from Gaseous CO2 and CH4 over Semiconductor

Photoinduced synthesis of CO2 and CH4 was investigated using a batch reaction system on several photoactive materials supported on silicon dioxide. Single semiconductor showed higher selectivity to C1 compounds. The production of C2-C3 oxygenates took place preferentially on composite semiconductor photocatalysts. In particular, it was found that acetone was the primary product over Cu/CdS-TiO2/SiO2.     

生活中的物理知识

日常生活中有许多家用电器与我们学习的知识有着密切关系，可是当学生遇到此类问题时，就不能正确解答因此在教学中应注意，利用生活中的实物分析物理问题会收到良好的效果。