A coupling VWM/CFD/CSD method for rotor airload prediction

A coupling fluid-structure method with a combination of viscous wake model(VWM),computational fluid dynamics(CFD) and comprehensive structural dynamics(CSD) modules is developed in this paper for rotor unsteady airload prediction. The hybrid VWM/CFD solver is employed to model the nonlinear aerodynamic phenomena and complicated rotor wake dynamics;the moderate deflection beam theory is implemented to predict the blade structural deformation; the loose coupling strategy based on the ‘delt method' is used to couple the fluid and structure solvers.Several cases of Helishape 7A rotor are performed first to investigate the effect of elastic deformation on airloads. Then, two challenging forward flight conditions of UH-60 A helicopter rotor are investigated, and the simulated results of wake geometry, chordwise pressure distribution and sectional normal force show excellent agreement with available test data; a comparison with traditional CFD/CSD method is also presented to illustrate the efficiency of the developed method.     

火箭橇体进水现象研究

在考核过载承受能力的火箭橇试验后,橇体内发现有水,从空气动力学的角度,对火箭橇体进水现象进行了初步分析,并利用FLUENT软件对进水原因进行了初步研究,通过分析,发现结构在穿越跨音速阶段时,由于内外压差的变化将导致内部或外部产生水汽。该发现为结构设计提供有益的建议。     

Global ionospheric scintillations revealed by GPS radio occultation data with FY3C satellite before midnight during the March 2015 storm

Global observations of S4 amplitude scintillation index by the GPS Occultation Sounder (GNOS) on FengYun-3 C (FY3C) satellite reveal global dynamic patterns of a strong pre-midnight scintillations in F-region of the ionosphere during the St. Patrick’s Day geomagnetic super storm of 17–19 March 2015. The observed strong scintillations mainly occurred in the low latitudes, caused by equatorial plasma bubbles. During the main storm phase (March 17), the scintillations were first triggered in the New Zealand sector near 160°E longitudes, extending beyond 40°S dip latitude. They were also enhanced in the Indian sector, but significantly suppressed in East Asia near 120°E longitude and in Africa around 30°E longitude. During the initial recovery phase (March 18–19), the global scintillations were seldom observed in GNOS data. During the later recovery phase (after March 19), the scintillations recovered to the pre-storm level in Indian, African, and American sectors, but not in East Asian and any of Pacific sectors. These results closely correlate with observations of the density depletion structures by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite, and ground-based instruments. Such consistency indicates reliability of our scintillation sensing approach even in a case-by-case comparison study. The prompt penetration electric field and disturbance dynamo electric field are suggested as the main factors that control the enhancement and inhibition of the scintillations during the storm, respectively.     

数字全息测量超高速撞击碎片云实验研究

在中国空气动力研究与发展中心(CARDC)超高速碰撞中心(HIRC)7.6 mm超高速碰撞设备的基础上，搭建纳秒级脉冲激光数字全息系统。提出滤波片和衰减片组合布置，减弱超高速碰撞等离子体自发光、提高信噪比的方法。实验获得了2.25 mm铝球弹丸以4.0 km/s的速度撞击0.5 mm厚铝板形成碎片云的全息图。采用小波变换算法对碎片云全息图进行重建，得到超高速撞击碎片云的三维结构和碎片大小。碎片云的轮廓呈椭球型，分为碎片云的前端、核心和外壳，碎片主要分布在弹丸破碎形成的碎片云核心，存在大碎片，且分布较集中，对后板的损伤也严重     

现代高效刀具发展特点和产业化途径

现代高效刀具和工具工业的发展特点 1 现代高效刀具的内涵 现代高效刀具是相对传统标准刀具而言的.传统的工具工业以生产供应标准化、通用化的刀具为基本特点.长期以来,制造业有一种共识:除了少量特殊需要,尽量选用标准刀具.标准刀具虽然性能不是最优,但因经济实用而被广泛接受.但到20多年前,这种观念在发达国家开始发生变化.     

航天器安全防护保障探讨

把对航天器安全的威胁分为硬和软两大类，分析了对航天器产生威胁的类别，以及为保证航天器安全而需要采取的措施。介绍了研究的内容，需要建设的空间信息对抗系统和空间信息探测网。     

一种GPS定位信息可用性的实时判定方法

基于GPS接收机输出数据,采用3级AR模型来预测下一时刻的GPS输出值,并与实际的输出值相比较,以一定的检测门限,判断当前时刻定位信息的可用性。通过仿真证明该方法的有效性,为GPS的可用性判定提供了一种方法。     

基于三机冷备份的遥感器计算机系统冗余设计

文章对当前比较流行的计算机冗余模型进行了分析和比较,制定出了三机冷备份的冗余计算机结构,并对关键电路进行了设计。     

技术创新型企业商业生态系统形成机制探讨——基于深圳市大疆创新科技有限公司的案例分析

商业生态系统构建是企业应对复杂环境变化,充分整合利用资源,实现信息共享的重要手段,也是现代企业走向成功的关键。通过对深圳市大疆创新科技有限公司的案例分析,分阶段阐述了技术创新型企业商业生态系统形成机制,构建了商业生态系统开拓与发展的整合模型。研究发现:技术创新型企业在商业生态系统开拓阶段的主要任务是通过地域选择、资源利用和市场开发以达到选择和融入现有产业链、初步形成"产学研"结合以及顾客培养的目标;技术创新型企业在商业生态系统发展阶段的主要任务是通过市场扩张、后备力量开发、政策法律响应、社会形象塑造以实现消费群体重构、全面"产学研"结合、合法性认同以及品牌评价。