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排序方式: 共有313条查询结果,搜索用时 78 毫秒
191.
[编者按]亚洲国际航空展览会暨论坛将于今年9月在香港举行,本届展会将延续以往的B2B模式,致力于为航空公司,飞机、发动机制造商及航空电子、机舱维修和物流等业内专业人员提供交流的平台.究竟本届亚洲航展的规模如何?有哪些值得我们关注的亮点?带着这些问题,本刊记者采访了主办单位励展博览集团华东区副总裁李雅仪女士. 相似文献
192.
Mutagenic effects of heavy ion radiation in plants. 总被引:5,自引:0,他引:5
M Mei H Deng Y Lu C Zhuang Z Liu Q Qiu Y Qiu T C Yang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):363-372
Genetic and developmental effects of heavy ions in maize and rice were investigated. Heavy particles with various charges and energies were accelerated at the BEVALAC. The frequency of occurrence of white-yellow stripes on leaves of plants developed from irradiated maize seeds increased linearly with dose, and high-LET heavy charged particles, e.g., neon, argon, and iron, were 2-12 times as effective as gamma rays in inducing this type of mutation. The effectiveness of high-LET heavy ion in (1) inhibiting rice seedling growth, (2) reducing plant fertility, (3) inducing chromosome aberration and micronuclei in root tip cells and pollen mother cells of the first generation plants developed from exposed seeds, and (4) inducing mutation in the second generation, were greater than that of low-LET gamma rays. All effects observed were dose-dependent; however, there appeared to be an optimal range of doses for inducing certain types of mutation, for example, for argon ions (400 MeV/u) at 90-100 Gy, several valuable mutant lines with favorable characters, such as semidwarf, early maturity and high yield ability, were obtained. Experimental results suggest that the potential application of heavy ions in crop improvement is promising. RFLP analysis of two semidwarf mutants induced by argon particles revealed that large DNA alterations might be involved in these mutants. 相似文献
193.
A model for discrimination and prediction of mental workload of aircraft cockpit display interface 总被引:4,自引:1,他引:3
With respect to the ergonomic evaluation and optimization in the mental task design of the aircraft cockpit display interface, the experimental measurement and theoretical modeling of mental workload were carried out under flight simulation task conditions using the performance evaluation, subjective evaluation and physiological measurement methods. The experimental results show that with an increased mental workload, the detection accuracy of flight operation significantly reduced and the reaction time was significantly prolonged; the standard deviation of R-R intervals(SDNN) significantly decreased, while the mean heart rate exhibited little change; the score of NASA_TLX scale significantly increased. On this basis, the indexes sensitive to mental workload were screened, and an integrated model for the discrimination and prediction of mental workload of aircraft cockpit display interface was established based on the Bayesian Fisher discrimination and classification method. The original validation and cross-validation methods were employed to test the accuracy of the results of discrimination and prediction of the integrated model, and the average prediction accuracies determined by these two methods are both higher than 85%. Meanwhile, the integrated model shows a higher accuracy in discrimination and prediction of mental workload compared with single indexes. The model proposed in this paper exhibits a satisfactory coincidence with the measured data and could accurately reflect the variation characteristics of the mental workload of aircraft cockpit display interface, thus providing a basis for the ergonomic evaluation and optimization design of the aircraft cockpit display interface in the future. 相似文献
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RESEARCHONTHE3┐AXESROUGHMILLINGOFMULTI┐SURFACESLiuZhuang,ZhangDeqiang,ZhouLaishui,ZhouRurong(ResearchCenterofCAD/CAMEngineeri... 相似文献
199.
高精度温控阀测控方法的研究 总被引:1,自引:0,他引:1
温控阀是航天飞行器中的一个重要组成部件 ,由于其过程具有明显的滞后和阻尼 ,因此在控制过程中极易产生超调和振荡 ,控制精度难以保证。本文提出一种高精度温控阀测控方法 ,它采用集散控制技术和 Fuzzy-PID复合控制算法 ,通过对温控阀的开度进行闭环控制 ,实现了混合点温度的稳态控制和扰动抑制 ,控制精度优于± 1℃。该方法已成功地应用于我国载人飞船温控系统零部件性能测试设备中 ,满足了航天飞行器的测控要求 相似文献
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