几种航空有源电子干扰装备的比较

本文对远距离支援干扰飞机、随队支援干扰飞机、机载自卫电子对抗系统以及最近国外正在大力发展的分布式电子干扰系统等几种航空有源电子干扰装备的作战对象、战术应用、功能、使用局限性等特点进行了比较 ,探讨了综合发展和运用这几型装备的重要意义     

3.5代通信中链路自适应技术的研究和仿真

3.5代移动通信中的链路自适应技术使用自适应调制编码和快速混合重传技术替代了3代中使用的功率控制技术。仿真结果比较了这两种新技术与功率控制技术的性能,证明了这两个新技术显著地提高了网络平均的吞吐量。     

工频电场对ADSS光缆特性的影响

随着电压等级的不断提高,超高压输电线路发展非常迅速.但是这些架空输电线路在运行时,附近存在较高的电场,对周围物体和公用走廊的其它线路会产生影响.电压等级越高,产生的电场影响越大.输电线路产生的电场越来越受到人们的重视.尤其是对于超高压输电线路,由于在电力铁塔上同塔悬挂全介质自承式光缆(ADSS),因此分析工频电场对ADSS光缆特性的影响非常必要.     

光场力对烧蚀物时空分布的影响

对烧蚀物的时空分布进行了研究。烧蚀物离开靶材表面时的速率分布由蒸发机制决定,在激光作用时间内烧蚀物的传输行为由扩散机制和光场力机制共同决定,激光作用结束后烧蚀物的传输行为由扩散机制单独决定,并解释了烧蚀物的时空分布及烧蚀物趋光运动的现象。     

Improving Measurement Precision of Test Batteries Using Multidimensional Item Response Models.

A conventional way to analyze item responses in multiple tests is to apply unidimensional item response models separately, one test at a time. This unidimensional approach, which ignores the correlations between latent traits, yields imprecise measures when tests are short. To resolve this problem, one can use multidimensional item response models that use correlations between latent traits to improve measurement precision of individual latent traits. The improvements are demonstrated using 2 empirical examples. It appears that the multidimensional approach improves measurement precision substantially, especially when tests are short and the number of tests is large. To achieve the same measurement precision, the multidimensional approach needs less than half of the comparable items required for the unidimensional approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

反应注射成型工艺进展

本文介绍了反应注射成型新工艺和演变过程，论述反应注射成型工艺所需新材料及其发展．     

Elastic wave propagation in bone in vivo: methodology

The purpose of this study was to investigate the usefulness of elastic wave propagation (EWP) in estimating the mechanical properties (elasticity) of human tibia. The test group was composed of 78-yr-old women assigned to high (n = 19) and low (n = 17) bone mineral density (BMD) groups as measured at the calcaneus by the 125I-photon absorption method. The EWP apparatus consisted of an impact-producing hammer with a force strain gauge and two accelerometers positioned on the bone. Results for nylon and acrylic were used to calibrate the apparatus. Polyvinyl chloride (PVC) solid rods and tubes of various diameters were used to evaluate the relationship between the elastic wave velocity and cross-sectional area. The density and the cross-sectional area of tibia were measured by the computerized tomographic (CT) method at the same intersection points as velocity recordings. The velocities in tibia of bending waves produced by the mechanical hammer were found to depend on the density, area moment of inertia, and density-dependent elastic constants of bone. It is important to account for the changes of these quantities along the bone. It is suggested that the velocity of elastic waves and various indices derived there from provide inexpensive ways of evaluating the elastic properties of bone.