卫星通信上的QoS分析

卫星链路由于其固有的特点(长时延，非对称环境)对QoS(Quality of Service）提出新的要求和挑战，本文首先对两种QoS策略进行讨论．然后对其在卫星链路上的性能及以后研究的方向进行了讨论。     

卫星链路上TCP协议问题透析

本文是卫星链路上 TCP协议问题及解决方案的综述。文章归纳了卫星链路上 TCP协议存在的问题 ,并且分类总结了已经提出来的各种解决方案 ,进行了详细的分析比较 ,提出了作者的观点     

大面积高温超导薄膜临界温度无损伤测试

我们设计并制作了高温超导薄膜无损伤超导转变温度Tc测试系统, 可以在直径2英寸范围内同时测量13个位置上的Tc.测试过程中可以用图形或数字监视薄膜的超导转变,方便可靠.系统采用液氮制冷,测试速度快,测量误差约±0.2K.对于直径2英寸或小于2英寸薄膜的Tc,本系统是一套实用可靠的测量设备.     

基于多模谐振器的三通带滤波器的设计CSCD

利用一种新型多模谐振器设计了三通带滤波器。新提出的多模谐振器采用四模谐振器加载两个开路枝节构成,能够产生六个传输极点。该滤波器经过仿真设计后进行实物加工,测试得到各通带的中心频率分别为2.55,3.83,6.00 GHz,相对应的插入损耗分别为0.9,0.7,2.3 d B,与仿真结果吻合良好。该滤波器具有回波损耗小、尺寸小的优点,可应用到现代无线和移动通信中。     

Measurement of anomalous nuclear reaction in deuterium-loaded metal

This paper reports on an experiment for testing natural nuclear fusion at low temperature searching for evidence of the origin of ³He from natural nuclear fusion in deep Earth. The experiment was carried out using deuterium-loaded titanium foil samples and powder sample. Detection of charged particle was carried out using a low-level charged particle spectrometer. An Al foil was used as an energy absorber for identification of charged particle. Although the counting rate is very low in the experiment, the emission of energetic particle from the sample is observed and the particle is identified as a proton having energy about 2.8 MeV after exiting the titanium sample. This work provides a positive result for the emission of charged particle in the deuterium-loaded titanium foil samples at low temperature, but a negative result for the deuterium-loaded titanium powder sample. The average reaction yield is deduced to be (0.46±0.08) protons/h for the foil samples. With the suggestion that the proton originates from d--d reaction, we calculate the reaction rate for d--d reaction, and the obtained result is 1.4× 10^-24 fusion/d--d\cdot sec. The negative result of the deuterium-loaded titanium powder sample suggests that the reaction yield might be correlated with the density or microscopic variables of deuterium-loaded titanium materials. The negative result also indicates that d--d reaction catalysed by μ-meson from cosmic ray can be excluded in the samples in this experiment.     

厚透镜近似下激光驻波场中原子动力学研究

研究了在厚透镜近似下 ,原子在激光驻波场中的动力学行为 .通过直接演化一维薛定谔方程 ,发现当激光的强度较大时 ,原子束将会聚焦形成几个焦点 .如果激光的强度更大 ,驻波场中的原子将会出现一种“隧道”现象 ,此时 ,原子受一些实验参数 (如焦平面位置、激光强度等 )的影响程度将大大降低 .这种现象有利于提高原子在驻波场中聚焦沉积的效果 . The dynamics of atoms in laser standing wave (SW) in the regime of over-focused immersion-lens is studied. Through directly evolving a one-dimensional Schrdinger equation, we find that multiple focusing appears when laser intensity is larger than that required for simple focusing. If laser intensity is much higher than that for the single focusing, a "channeling" phenomenon appears, which is insensitive to the variation of some parameters, such as focal plane position and laser intensity...     

加速器质谱技术在核物理与天体物理中的应用

介绍了利用加速器质谱技术在核物理与核天体物理中的应用研究工作．包括放射性核素半衰期的测定、核反应截面的测量、超重元素的寻找、宇宙射线和太阳中微子性质等方面的研究工作.The application work which has been done and can be done in the nuclear physics and nuclear astrophysics using accelerator mass spectrometry is reviewed. The half-life measurement of long-lived radio isotopes, cross section measurement of nuclear reaction, searching for super heavy elements, cosmic study and solar neutrino detection are the main components which have been discussed     

用于LTE-A中继系统的准动态频率资源划分方法

为了减少LTE-A中继系统内的干扰,针对采用正交频分多址接入(OFDMA)技术的下行链路,提出了一种新的准动态频率资源划分方法。该方法适用于小区内所用频率资源不连续的场景。该方法通过将频率资源设定为已聚合的多个连续频率资源,避免了部分邻频干扰。依照基站及中继站的分布与数目,对频率资源进行均匀划分及合理调配,减少了同频干扰源的数目,提高了用户的平均频谱效率。通过准动态的空闲频率资源分配,提高了频率资源的利用率。大量的仿真结果表明,提出方法能够有效地提高用户的信号干扰噪声比(SINR)以及平均频谱效率。     

云计算技术发展及应用探讨

云计算被视为IT业的下一次革命,将对工作方式和商业模式带来根本性的改变。其概念于2007年提出,是随着虚拟化技术、分布式存储技术、网格技术和自动化管理技术的发展产生的,能够提供一种更加灵活配置应用的途径。本文首先介绍了云计算的关联概念,其次对云计算的功能特性、体系结构以及应用意义进行了综合分析,最后对云计算的未来发展趋势做了展望。     

C波段卫星通信中高温超导双工器的研制

文中提出一种紧凑型的c波段高温超导双工器的设计方法,利用一个公共输入节点和两个带通滤波器组成双工器。公共节点是由中心谐振频率处在防护频带上的开环微带环实现,每个带通滤波器都包括四个矩形螺旋线谐振器。双工器的中心频率为4GHz,带宽为0.23GHz。该双工器采用氧化镁衬底双面镝钡铜氧高温超导薄膜加工而成,薄膜上下表面均溅射金保护层。将超导双工器封装在铜制屏蔽盒中并在机械制冷机(77K温度条件)中测试。实验结果表明,每个信道的插入损耗低于0.1dB,两个信道间的隔离度超过40dB。仿真和实验结果达到很好的吻合,有效的说明了设计方法的正确性。