我校学生思想政治状况调查报告

近期我们对我校５６０名学生进行了问卷抽样调查，调查共发出问卷５６０份，回收５６０份，回收率为 １００％，全部为有效问卷。为确保调查的客观性、科学性，在抽样过程中，我们充分考虑了专业特色、学制特色，其中中专生１７５人，占３１．３％，高大专１７８人，占３１．８％，五年制大专２０７人，占３７％；电气系２０７人，占３６．９６％，机械系１７８人，占３１．７８％，计算机系８４人，占１５％，动力系５０人，占８．９％；从家庭来源看，大中城市６１人，占１０．８％，城镇１３０人，占２３．２１％，农村３６８人，占６５…     

K—8飞机操稳特性试飞

主要介绍Ｋ－８飞机在鉴定试飞中的操纵性，稳定性试飞方法和结果，其中包括起飞，着陆，速度稳定性，过载稳定性，机动点，中性点的确定，同时还对纵向模态特性，横侧静稳定性，操纵性，滚转效率，横侧动态特性进行了测定，并在各特性的测定中谈了飞行体会。     

用火焰原子吸收光谱法测定飞行员头发中Ca,Mg,Cu,Pb,Fe,Zn？…

人发样品是生物类有机样品，用火焰原子吸收光谱法测定人发中Ｃａ，Ｍｇ，Ｃｕ，Ｐｂ，Ｆｅ，Ｚｎ元素时，采用硝酸：高氯酸＝４：１消解体系，电热板加热常压消解大约２小时，样品呈湿盐态，以去离子水稀释定容，测定溶液为无色，透明，分别上机测定以上各元素，本测定方法技术关键在于消解温度不得超过２５０℃消解完全后要赶尽高氯酸，测定Ｃａ，Ｍｇ时，用０．１％ＳｒＣｌ２水溶液定容，以消除共存物的干扰，对各元素的仪器测定     

姜长英传略(上)

姜长英，年龄与世纪同步，经历与世纪同行，一身坎坷，半世奋斗，为航空教育事业和航空史研究，呕心沥血，鞠躬尽瘁，硕果显赫，德高望重。     

基于神经网络的稳M数非线性控制

介绍风洞稳Ｍ数神经网络的非线性控制，包括预测模型，动态优化和反馈校正原理，以实现速度快，精度高，低耗油的优化控制目标，试验表明，该系统不仅稳Ｍ数控制精度高，响应速度快，而且鲁棒性好，节省燃油。     

奋战一年再扬鞭 努力开创新局面

中航第二集团公司成立一周年以来，针对“三少一多”的困难，顽强拼搏，开拓进取，抓发展，抓机遇，抓改革，抓创新……，抓出了一片新局面     

利用GPS提高测量船的测位和测姿精度

测量船是海上活动观测站，船上配有精密跟踪测量雷达和光学经纬仪等测控设备，要精确观测空间飞行器的运动轨迹或弹道，就必须精确测定船体的位置，速度，姿态和航向，我国早期测量船上的导航系统使用避限性很大，而且相当落后，已经不能满足当代海上作业的精度要求，急需更新。目前，我国GPS已全面投入运行，利用该系统测定测量船的位置和姿态，不仅精度高，实时性强，而且操作简便，设备成本低，借助差分导航，组合导航等技术还可以进一步提高其定位测姿精度，不久的将来，俄罗斯的Glonass也将投入运行，且工作性能与GPS基本一样，可作GPS的补充导航能力。     

DSP在惯性技术中的设计与应用

DSP具有速度快，精度高，价格低等特点，而惯性技术要求信号处理具有响应时间快，运算精度高，可靠性好，DSP非常适合于在惯性技术中应用，作者介绍了DSP的特点，设计方法，DSP在捷联系统中的应用，以及世界DSP厂商和产品等内容。     

怀念我的流体力学启蒙老师--凌云沛教授

1952年暑假结束，我们清华大学航空学院二年级学生120多人从上海、太原工厂实习结束，回到清华园气象台下、梁思诚教授新设计建成的大玻璃窗宿舍内，老师宣布院系调整，成立北京航空学院，抽调我们班各30人组成苏联学制的飞机工艺和发动机工艺两个班进城住钱粮胡同，到原中法大学，现属北京工业学院的亮果厂一个小院上课。其中还有从北京工业学院进城的一个三年级，一个四年级飞机设计专业的两个班。我们清华大二班余下留在清华的人，按照第一个五年计划需要于1953年学满3年提前毕业，按本科分配工作。很快，我们60人就搬进城，开始了三年级的苏联课程学习。从课程表上看到，有一门“流体力学和流体机械”，我有点纳闷，这个课和我们飞机工艺专业有什么关系呢？上课了，老师是一位中年人，敦实的体型，他自我介绍叫凌云沛，由四川大学合并而来。北京的秋天，降温时，已可戴棉帽。进教室后，他打开遮耳片，往上拉，但没有系好带子，随着讲课，头一摆动，耳片也跟着左右摇动，像个官帽似的，同学们不禁暗暗发笑，他也不觉得。他讲课认真，清楚，很吸引我们。一学期很快过去，北航第一次实行苏式五分制口试，这门课首当其冲，而我又不知为何成为第一个接受考试的人，只好听天由命了。考场设在亮果厂这4个班的小饭厅，一张大圆桌，差不多放了两圈椅子凳子。苏联专家，沈元院长都在，教师们都坐满了来学习苏联考试经验。抽题准备一下后就开始考试，我感到凌老师比我还要紧张似的。最后，他对我讲：对你的口试，我觉得可以，给你4分，你有什么意见？我想都没有想过还要征求我的意见，我表示同意，就退出到图书馆去复习下一门功课。没有多久，教务处张女士来找我，叫我跟她到考场去。     

旅客航站楼规划设计的思考

建设一流的机场，必须有一流的设计，机场跑道确定后旅客航站楼的规划设计历来都是机场设计的核心，其中值得研究，探讨的问题颇多，国内外部在不断地探索和实践，文章根据近几年来在进行旅客航站楼的规划设计中，对一次规划，分期建设，滚动发展之间的衔接，功能性与民族形式，国内设计航站楼的安全等级与国外相同规范的差距，以及旅客站楼工艺流程的设计等问题，进行了有益的思考，并提出一些新的看法，供研究与探讨。     

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 ℃).     

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.      

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.     

Thermal Stresses and Cracks During the Growth of Large-sized Sapphire with SAPMAC Method

本文利用有限元法对冷心放肩微量提拉法(SAPMAC)生长大尺寸蓝宝石单晶过程中的热应力进行了模拟计算,应用临界缺陷理论解释了裂纹的萌生与扩展机理。研究表明,晶体内的热应力主要与晶体生长速率,环境温度和结晶取向有关;较大热应力多出现在结晶界面,放肩、收尾以及直径急剧变化等位置;最大热应力总是出现在籽晶与新生晶体的界面附近。裂纹将在临界缺陷位置产生,并在应力作用下沿a或m面扩展。计算结果与实验结果基本吻合,通过晶体生长系统和生长工艺的改进,对晶体的开裂问题得到了有效的抑制。     

LES of film cooling for different jet fluids

The present paper investigates the impact of the velocity and density ratio on the turbulent mixing process in gas turbine blade film cooling.A cooling fluid is injected from an inclined pipe at α=30° into a turbulent boundary layer profile at a freestream Reynolds number of Re∞=400000.This jet-in-a-crossflow(JICF) problem is investigated using large-eddy simulations(LES).The governing equations comprise the Navier-Stokes equations plus additional transport equations for several species to simulate a non-reacting gas mixture.A variation of the density ratio is simulated by the heat-mass transfer analogy,i.e.,gases of different density are effused into an an air crossflow at a constant temperature.An efficient large-eddy simulation method for low subsonic flows based on an implicit dual time-stepping scheme combined with low Mach number preconditioning is applied.The numerical results and experimental velocity data measured using two-component particle-image velocimetry (PIV) are in excellent agreement.The results show the dynamics of the flow field in the vicinity of the jet hole,i.e.,the recirculation region and the inclination of the shear layers,to be mainly determined by the velocity ratio.However,evaluating the cooling efficiency downstream of the jet hole the mass flux ratio proves to be the dominant similarity parameter,i.e.,the density ratio between the fluids and the velocity ratio have to be considered.      

New Cutting Force Modeling Approach for Flat End Mill

A new mechanistic cutting force model for flat end milling using the instantaneous cutting force coefficients is proposed. An in-depth analysis shows that the total cutting forces can be separated into two terms: a nominal component independent of the runout and a perturbation component induced by the runout. The instantaneous value of the nominal component is used to calibrate the cutting force coefficients. With the help of the perturbation component and the cutting force coefficients obtained above, the cutter runout is identified. Based on simulation and experimental results, the validity of the identification approach is demonstrated. The advantage of the proposed method lies in that the calibration performed with data of one cutting test under a specific regime can be applied for a great range of cutting conditions.     

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。     

吸气式高超声速飞行器大迎角气动特性分析

吸气式高超声速飞行器在飞行过程中受到大气紊流等外部干扰的作用时,飞行姿态很可能会出现大迎角情况。针对大迎角飞行时飞行器可能出现的气动问题,对一种典型吸气式高超声速飞行器的流场进行了数值模拟。以雷诺平均Navier-Stokes(RANS)方程为控制方程,采用标准k-ε湍流模型求解,得到其流场特征和气动特性。重点针对大迎角情况,分别对整机气动特性、进气道性能和全动尾翼气动性能进行了分析,并结合流场特征作出解释。结果表明,机身和发动机之间存在气动/推进耦合现象。大迎角下飞行器的气动参数表现出非线性特性,升阻比减小,整机纵向表现为静不稳定,且不稳定性随迎角增大而增大;进气道性能在大迎角下降低,从而导致发动机推力下降,不利于发动机的正常工作,但却适当降低了整机的纵向静不稳定度;全动尾翼操纵效率降低从而使得配平难度增大。     

Power characteristics of a variable hydraulic transformer

The flow control of hydraulic transformers is a great challenge.To meet this challenge,a new kind of hydraulic transformer,variable hydraulic transformer(VHT),is proposed in this work.This paper focuses on the power characteristics of the newly proposed VHT,including instantaneous power,average power,power pulsation,and efficiency.In the analyses,the concepts of efficiency,input power,output power,starting angle,and ceasing angle are defined or redefined.To investigate the power characteristics,their models are derived by considering the governing factors such as the control angle of the swash plate and the structure of the port plate.This work highlights that the load flow can be adjusted by adjusting the control angle of the swash plate,and the power characteristics at the B-port produce a remarkable change.In addition,the VHT has a starting angle and a ceasing angle,and these two angles can be adjusted by the influencing factors.The results reveal that the power pulsation and the jump points of the instantaneous power are the primary causes of a less smooth work.Then,it is shown that the control angle of the port plate,the control angle of the swash plate,and the pressures at the ports are the three key elements for a stable operation.The results also reveal that the adjustment of the influencing factors can improve the efficiency.     

三角波信号波形参数的测量不确定度

通过使用波形测量手段和最小二乘直线拟合方法，对三角波信号的波峰、波谷、中值、幅度、频率、沿斜率、沿线性度、对称性等指标进行了精确评价，详细讨论了方法的实现过程以及有关技术问题，并对各项参数指标进行了不确定度分析。实验验证结果表明了该方法的有效性和实用性，该方法可应用到三角波信号源的性能指标评价中。