中部地区的战略定位:中国经济增长第四极

中部地区是我国全面建设小康社会的重点区域,是我国新型工业化的主战场,是我国区域经济协调战略中的重要枢纽,将中部地区定位中国经济增长第四极具有十分重要的意义.中部地区具有较强的经济实力和经济联系,丰富的自然资源和雄厚的产业基础,突出的区位优势和优越的交通条件,较雄厚的科技实力和不竭的创新能力,完全可以建设成为中国经济增长"第四极".     

国航技术成都基地:坚持技术致胜发展战略

国航工程技术分公司成都维修基地成立7年来,坚持以思维创新推动维修实力,以技术创新拓展市场份额,其维修能力和维修业绩有了突飞猛进的发展,成为中国中西部地区最大的综合     

2006年世界航天活动大盘点

今年是世界航天发展较为平稳的一年,美国、俄罗斯、欧洲、中国和日本等主要航天国家和地区继续通过多种类型航天器的发射进一步发展了各自的航天实力,并有更多的国家通过自主或委托别国研制、发射卫星的方式加入到航天国家的行列中来.     

共创中国通用航空发展的春天

近年来我国通用航空事业取得了长足的发展,2006年的各项指标均达到了历史最高水平,但同航空运输相比,在行业实力和发展速度等方面差距明显。为促进通用航空发展,民航总局近期做出了一系列的重大举措。随着国民经济的快速发展,我国通用航空事业正面临前所未有的发展机遇,迎来了发展的春天。     

金融发展不平衡、教育不平等与地区收入差距

金融发展不平衡是地区间居民收入差距产生的重要原因.文章运用中国1978～2007年的时序数据,在VAR模型的框架下研究了地区金融发展不平衡和地区间教育不平等对地区收入差距的影响.研究结果表明:(1)我国金融发展不平衡、教育不平等与地区收入差距之间存在长期稳定的相关关系;(2)不论对于长期还是短期而言,金融发展不平衡和教育不平等均会拉大地区收入差距;(3)我国各地区金融发展不平衡是城镇和农村地区收入差距的单向格兰杰原因,教育不平等是城镇地区收入差异的双向格兰杰原因,是农村地区收入差异的单向格兰杰原因.因此,改善我国的收入分配状况,缩小地区差距,应从解决金融发展的地区间非均衡问题和教育不平等问题着手.     

用中国数控精品装备中国

介绍了 2 0 0 2年中国数控机床展览会(CCMT 2 0 0 2 )的内容、规模及近年来我国数控机床发展的特点。     

南中国海地缘安全问题与战略选择

中国在南海地区有着重要的地缘战略利益.南海是我国近海防御的战略屏障,是我国“岛屿防御”的重要链条,是重要的国际贸易通道,南海的能源资源有助于缓解中国未来能源供应严重不足的困境.随着大国地缘实力的介入以及东盟国家的大国均衡政策,南海安全形势日益国际化,复杂化.缓解南海地区的安全紧张形势,必须加强以海权为重点的地缘实力建设,尽快制定南海资源开发战略,加大海洋执法力度,加强地缘文化建设,大力扩大中华文化的影响,逐步建立多层次、复合型的东南亚安全合作机制.     

中部地区城市化发展战略研究

中部地区与东部地区在经济实力和经济发展水平上的差距。主要是由城市化和城市经济上的差距决定的。中部地区城市化落后于全国平均水平。省与省之间城市化水平差距大。城市化落后于工业化和非农化。在当今城市呈集群发展的趋势背景下。中部地区城市化发展的战略重点在于大力培育城市群。推进中部城市化。必须以新型城市化模式不断解决城市发展中的问题。构建完善的基础设施平台，提升中部地区城市化发展的产业支持能力。实现城市发展的良性循环。     

国外光电子产业创新网络的发展与启示

光电子技术具有复杂性和融合性特征,光电子产业将引领未来高技术产业的发展,技术创新需要借助外部合作的方式实现.欧美光电子产业发达国家的经验表明,光电子产品特色各异,但创新网络发展初期的核心节点成长很重要.商业氛围浓厚和科研实力强劲的地区适合发展弱联系网络;技术后进地区适合发展以中介组织为核心的强联系网络.     

北京航空航天大学电子信息工程学院成立五十年

北航电子信息工程学院的前身航空无线电系成立于1958年10月29日,是我国最早建立的航空电子类专业。历经50年,尤其是改革开放30年来,在学校的领导和支持下。学院几届党政领导班子和广大师生员工齐心协力、锐意进取,抓住“211工程”、“985工程”等建设契机,拓宽学科布局,扩大办学规模,增强师资力量,学院的综合实力发生了历史性的变化,实现了跨越式发展。     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.