信息化条件下直升机维修保障人才培训体系

针对目前直升机维修保障力量难以适应信息化作战保障要求的问题,对直升机维修保障人才培训的特点和规律进行研究。介绍信息化条件下直升机维修保障人才培训的新特点,分析当前影响直升机维修保障人才培训效益的主要因素,从5个方面提出了信息化条件下直升机维修保障人才培训体系建设措施。研究结果表明:该体系为直升机专业院校和直升机部队的维修保障人才培训提供了理论依据,能促进直升机维修保障人才培训能力的提高。     

基于杂草入侵算法的天线阵列方向图可重构优化

利用杂草入侵算法对线阵天线进行方向图可重构优化,在未给定阵元公共幅值的情况下,对激励幅值和相位同时优化,通过改变加权相位分别实现余割波束和笔状波束赋形。仿真结果得到较低的峰值旁瓣电平及较好的波束形状,表明了该算法是有效可行的。     

Microwave link dual-wavelength measurements of path-averageattenuation for the estimation of drop size distributions and rainfall

Microwave attenuation measurements at 25 and 38 GHz made on a 2.3-km microwave link are employed to estimate drop size distributions (DSD), rainfall rate, and rainfall accumulation. A theoretical model for the propagation of microwaves in a link system sets forth the basis for the development of a dual-wavelength analytical technique to invert two parameters of a path-average gamma DSD. The DSDs obtained from the technique are evaluated in conjunction with point measurements performed with a 2-D video disdrometer. Additionally, the DSDs yield path-average rainfall rates and rainfall accumulation which are compared with path-average measurements from a network of optical and tipping bucket rain gauges located beneath the link path, and with estimates based on empirical power law relations     

小型无线设备的Web业务技术研究

无线Web业务逐渐成为通过Internet接入业务事实上的标准,在小型设备上开展Web业务需要相关Web业务技术的发展.文章给出了移动设备中的Web业务栈,分析了无线Web业务领域的发展现状与发展方向,研究了小型无线设备的HTTP协议和SOAP协议,阐述了Web业务规范通用描述、发现与集成(UDDI)技术的工作原理,最后详细介绍了小型无线设备的业务执行与进程.     

RBFT:基于Raft集群的拜占庭容错共识机制

针对现有联盟链共识机制因可拓展性不足,无法在支持大规模网络的同时满足低时延、高吞吐量和安全性的问题,采用网络分片的思想,提出一种适用于联盟链的带有监督节点的两级共识机制——RBFT.首先对网络节点进行分组,组内采用改进的Raft机制进行共识,然后由每个组内选出的领导者组成网络委员会,网络委员会内部采用PBFT机制进行共...     

Effect of concentration of cadmium sulfate solution on structural,optical and electric properties of Cd1-xZnxS thin films

Cd1-xZnxS thin films were deposited by chemical bath deposition(CBD)on the glass substrate to study the influence of cadmium sulfate concentration on the structural characteristics of the thin film.The SEM results show that the thin film sur-faces under the cadmium sulfate concentration of 0.005 M exhibit better compactness and uniformity.The distribution dia-grams of thin film elements illustrate the film growth rate changes on the trend of the increase,decrease,and increase with the increase of cadmium sulfate concentration.XRD studies exhibit the crystal structure of the film is the hexagonal phase,and there are obvious diffraction peaks and better crystallinity when the concentration is 0.005 M.Spectrophotometer test results demonstrate that the relationship between zinc content x and optical band gap value Eg can be expressed by the equation Eg(x)=0.59x2+0.69x+2.43.Increasing the zinc content can increase the optical band gap,and the absorbance of the thin film can be improved by decreasing the cadmium sulfate concentration,however,all of them have good transmittance.At a concen-tration of 0.005 M,the thin film has good absorbance in the 300-800 nm range,80％transmittance,and band gap value of 3.24 eV,which is suitable for use as a buffer layer for solar cells.     

Harmonic distortion due to laser modulation in multimode fibre optic analogue transmission

The effect of laser-diode frequency chirping on harmonic distortions in multimode fibre analogue transmission with direct intensity modulation was clarified experimentally with results in good agreement with the theory. The results show that the harmonic distortion can be greatly reduced by the reduction of the frequency chirping which accompanies diode-laser intensity modulation.     

激光头主板用FPC关键材料研究

FPC有广阔的发展及应用空间,对FPC的的卷曲、弯折以及温度和湿度载荷下的疲劳可靠性也有了更高的要求。本文通过对激光头主板用FPC关键材料的实验研究,通过对比实验选择出了提高激光头主板FPC电路的弯折性的FPC材料,其产品电路的弯折达1000万次,达到国内的先进水平。     

A microwave scattering model for layered vegetation

A microwave scattering model was developed for layered vegetation based on an iterative solution of the radiative transfer equation up to the second order to account for multiple scattering within the canopy and between the ground and the canopy. The model is designed to operate over a wide frequency range for both deciduous and coniferous forest and to account for the branch size distribution, leaf orientation distribution, and branch orientation distribution for each size. The canopy is modeled as a two-layered medium above a rough interface. The upper layer is the crown, containing leaves, stems, and branches. The lower layer is the trunk region, modeled as randomly positioned cylinders with a preferred orientation distribution above an irregular soil surface. Comparisons of results obtained using this model with measurements from deciduous and coniferous forests show good agreement at several frequencies for both like and cross polarizations