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| 1 | Research advance in failure risk and local strength failure for high arch dams显示文摘To develop national economy and use the water resources and hydropower resources sufficiently,a lot of high arch dams,with the height of more than 200 m,have been and will be built in China.Although arch dams have good mechanical behavior,there is still failure possibility due to the huge water pressure and high stress level in dam,complex topographic and geologic conditions,formidable environment and high intensity earthquake.As one of the three main aspects concerning the safety of high arch dam,the study on global destruction,has been elaborated in the literatures,and research advance in the other two aspects,namely the failure risk and local damage of high arch dams,will be reviewed in this paper.In recent years,the failure risk of high arch dams has been investigated,and the model for identifying dam failure risk factors has been established.It is shown that the foundation deterioration and strong earthquake are the major risk sources for high dam failure.With the fault tree method,the failure mode and failure probability of high arch dams are studied,and the principle for determining failure mode and the method of calculating failure probability are proposed.Meanwhile,the determination principle of acceptable risk standard for high arch dam was proposed,and the acceptable risk rate and the acceptable standard value of various risk losses were given.For the local damage of arch dam,it is pointed out that the local damage belongs to the strength failure at material level.The study on local failure mechanism of arch dam is reviewed,based on the theories that from traditional strength theory to damage mechanics and meso-mechanics theory.Aiming at the cracking,the main pattern of local failure of high concrete dam,the research advances in the analysis methods and cracking criteria for smeared crack model and discrete crack model are summarized,and the research findings of preventive measures for local failure are shown. | REN QingWen LI Qiang LIU Shuang | 2012 | Chinese Science Bulletin2012，57，36： | 5 |
| 2 | Experimental investigation on the wing-wake interaction at the mid stroke in hovering flight of dragonfly显示文摘This paper focuses on flow structures of the wing-wake interaction between the hind wing and the wake of the forewing in hovering flight of a dragonfly since there are arguments whether the wing-wake interaction is useful or not.A mechanical flapping model with two tandem wings is used to study the interaction.In the device,two identical simplified model wings are mounted to the flapping model and they are both scaled up to keep the Reynolds number similar to those of dragonfly in hovering flight since our experiment is conducted in a water tank.The kinetic pattern of dragonfly(Aeschna juncea) is chosen because of its special interesting asymmetry.A multi-slice phase-locked stereo particle image velocimetry(PIV) system is used to record flow structures around the hind wing at the mid downstroke(t/T=0.25) and the mid upstroke(t/T=0.75).To make comparison of the flow field between with and without the influence of the wake,flow structures around a single flapping wing(hind wing without the existence of the forewing) at these two stroke phases are also recorded.A local vortex identification scheme called swirling strength is applied to determine the vortices around the wing and they are visualized with the iso-surface of swirling strength.This paper also presents contour lines of z at each spanwise position of the hind wing,the vortex core position of the leading edge vortex(LEV) of hind wing with respect to the upper surface of hind wing,the circulation of the hind wing LEV at each spanwise position and so on.Experimental results show that dimension and strength of the hind wing LEV are impaired at the mid stroke in comparison with the single wing LEV because of the downwash from the forewing.Our results also reveal that a wake vortex from the forewing traverses the upper surface of the hind wing at the mid downstroke and its distance to the upper surface is about 40% of the wing chord length.At the instant,the distance of the hind wing LEV to the upper surface is about 20% of the wing chord length.Thus,there must be a wing-wake interaction mechanism that makes the wake vortex become an additional LEV of the hind wing and it can partly compensate the hind wing for its lift loss caused by the downwash from the forewing. | LAI GuoJun SHEN GongXin | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，11： | 2 |
| 3 | 纯引力轨道验证质量辐射计效应分析显示文摘纯引力轨道飞行器在精密导航、重力场测量以及基础科学研究等方面具有重要意义,辐射计效应是纯引力轨道验证质量的重要干扰力之一.针对内编队重力场测量系统,利用解析和数值计算相结合的方法,分析了内卫星辐射计效应与内编队系统参数的关系,并给出了适宜于工程计算的内卫星辐射计效应近似函数及其修正因子.分析可知,内卫星辐射计效应与腔体平均压力成正比,与腔体平均温度成反比;随腔体温差的增加而增加,随外卫星腔体半径的增加存在极小值,并且取极小值时外卫星腔体半径和内卫星半径比为常数1.189 4,这一常数是由内外卫星的球形腔体构型决定的,与腔体内温度和压力无关.当内外卫星半径比大于10时,可认为外卫星腔体充分大,此时内卫星辐射计效应与内卫星半径的平方近似成正比,随外卫星腔体半径的变化可忽略. | 刘红卫 王兆魁 张育林 | 2012 | 应用数学和力学2012，33，5： | 2 |
| 4 | Analysis of residual gas disturbance on the inner satellite of Inner Formation Flying System显示文摘The Inner Formation Flying System(IFFS) consisting of an outer satellite and an inner satellite which is a sphere proof mass freely flying in the shield cavity can construct a pure gravity orbit to precisely detect the earth gravity field.The residual gas in the cavity is a significant disturbance source due to the temperature inhomogeneity and relative motion of the inner satellite.The expressions of the disturbance forces were derived based on the property of rarefied gas,including the radiometer effect and the damping force.According to the current design of IFFS,heat transfer analysis of the cavity and the inner satellite was carried out,and the surface temperature distribution of the cavity and the inner satellite was given.The relative motion of the inner satellite was obtained from the formation control simulation of IFFS.Then the residual gas disturbance was calculated.The disturbance acceleration acting on the inner satellite due to the radiometer effect was on the order of 10-11 ms-2 and the damping acceleration was on the order of 10-15 m s-2. | GU ZhenFeng WANG ZhaoKui ZHANG YuLin | 2012 | Science China(Technological Sciences)2012，55，9： | 1 |
| 5 | 基于卫星自旋的纯引力轨道万有引力干扰抑制显示文摘一个称为'内卫星'的验证质量块位于外卫星的内部空腔中,不与外卫星接触而自由飞行,由于外卫星的屏蔽,其不受大气阻力、太阳光压等干扰作用,沿着纯引力轨道飞行。外卫星会对内卫星产生万有引力作用,是内卫星纯引力轨道的主要残余干扰。根据卫星相对运动动力学方程,建立了万有引力干扰对内卫星纯引力轨道影响的分析模型;基于将外卫星绕轨道面法向旋转以调制万有引力的策略,建立了外卫星自旋对万有引力干扰影响的抑制模型。以内编队纯引力飞行系统为例,对比计算了外卫星有无自旋时万有引力干扰对内卫星纯引力轨道的影响。基于模型的分析表明,外卫星自旋能够显著抑制万有引力干扰对内卫星纯引力轨道的长期影响;实例计算表明,万有引力干扰的天长期影响能够降低5~7个数量级。 | 谷振丰 王兆魁 张育林 | 2013 | 中国空间科学技术2013，33，4： | 1 |
| 6 | Analysis of radiometer effect on proof mass in purely gravitational orbit显示文摘Spacecrafts with the pure gravity environment are of great significance in precision navigation,gravity field measurement for celestial bodies,and basic physics experiments.The radiometer effect is one of the important interfering factors on the proof mass in a purely gravitational orbit.For the gravity field measurement system based on the inner-formation flying,the relationship between the radiometer effect on the innersatellite and the system parameters is studied by analytical and numerical methods.An approximate function of the radiometer effect suitable for the engineering computation and the correction factor are obtained.The analytic results show that the radiometer effect on the inner-satellite is proportional to the average pressure while inversely proportional to the average temperature in the outer-satellite cavity.The radiometer effect increases with the temperature difference in the cavity,and its minimum exists when the cavity radius increases.When the minimum of the radiometer effect arrives,the ratio of the cavity radius to the inner-satellite radius is 1.189 4.This constant is determined by the spherical cavity configuration and independent of the temperature and pressure distributions.When the ratio of the cavity radius to the inner-satellite radius is more than 10,it is believed that the cavity is large enough,the radiometer effect is approximately proportional to the square of the inner-satellite radius,and the influence of the outer-satellite cavity radius on the radiometer effect can be ignored. | 刘红卫 王兆魁 张育林 | 2012 | Applied Mathematics and Mechanics(English Edition)2012，33，5： | 0 |
| 7 | 纯引力轨道检验质量的相对测量技术显示文摘纯引力轨道是物体在太空仅受引力作用的运行轨道,通过构造纯引力轨道,可实现超高精度的空间引力探测,也可为科学实验提供超稳定卫星平台.作为纯引力轨道构造的核心,检验质量的相对测量不仅提供了部分任务科学数据,还为航天器平台的跟踪控制提供输入.首先,描述了纯引力轨道的概念内涵,总结了它在卫星重力测量、引力波探测等方面的应用情况.其次,综述了不同任务对相对测量的需求,给出了电容式测量、磁感应测量和光学测量的原理,总结了各自的优缺点.根据检验质量的姿态运动,将检验质量质心相对状态解算问题分为3类,给出了基于检验质量姿态动力学与表面建模的典型解算模型和质心速度估计方法.最后分析了非引力干扰的理论计算、地面实验验证和在轨实验验证问题. | 侯振东 王兆魁 张育林 | 2015 | 力学进展2015，45，1： | 0 |
| 8 | 纯引力轨道验证质量辐射计效应与气体阻尼耦合模型的数值分析显示文摘辐射计效应和气体阻尼是纯引力轨道验证质量的重要干扰力,是影响纯引力轨道构造水平的重要因素。在纯引力轨道飞行器中,这两种力分别描述了由腔体中温度梯度和验证质量相对运动引起的气体分子作用,两者从不同角度描述了气体分子作用力,均是气体分子作用力的一部分,而两者的耦合模型则可以反映验证质量受到的气体分子作用力总和。针对耦合模型形式复杂的特点,本文以内编队系统为例,利用数值方法分析了耦合模型中的影响因素,这些因素包括内卫星相对运动速度、内卫星半径、外卫星腔体半径、腔体平均温度、腔体温差和腔体平均压力等。对大量计算结果进行了数据拟合,给出了内卫星气体分子作用力与各物理参数关系的拟合公式,和原始计算结果相比,拟合误差在20%以内。 | 刘红卫 王兆魁 张育林 | 2012 | 国防科技大学学报2012，34，4： | 0 |
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