The gravitational potential for a moving observer, the perihelionshift of Mercury, and photon deflection

Acceptance of Einstein's second postulate, combined with the Principle of Equivalence, requires the introduction of space-time curvature in the presence of massive objects. In this paper, it has been demonstrated that the radiation continuum model (RCM) of light results in a modification to Newton's static gravitational potential. Applying this modified potential to the case of Mercury's anomalous perihelion advance accounts for the entire 43" per century, and provides a form equivalent to that of GRT. Thus, this model will work equally well for any system to which it is applied, all without resorting to the space-time curvature of GRT. The same potential, applied to the problem of a solar grazing photon, gives a solution identical in form and content to that of GRT as well. Such results lead to the conclusion that these effects are not attributable to massive objects curving space-time     

Projectile Detection of Luminous and Nonluminous Bodies

In a large hyperballistics range, detection of projectiles atstations becomes more complex. Range length permits variation of projectile luminosity and requires greater area for detection. A technique has been devised, using electrooptics, triggering instrumented stations with luminous or nonluminous projectiles. The phototube circuit response, effect of velocity, and effect of light screen thickness on performance are discussed. Data on performance are presented for velocities of 10 000 to 21 000 feet per second. Performance is predicted for velocities of 40 000 and 60 000 feet per second. Nonluminous models as small as 3/16-inch diameter spheres have been detected at a velocity of 21 000 feet per second.     

光速不变原理在相对论中的作用

本文首先通过速度附加定律的推导阐述了“光速不变原理”在狭义相对论中的作用,然后从公理化体系着手推导出洛仑兹变换式,从而进一步说明“光速不变原理”的作用。     

空间回路网法在隐身结构电磁散射计算中的应用

随着计算机技术的发展,计算电磁学得到了极大地发展和运用。它可以通过数值计算得到描述宏观电磁场的Maxwell方程组的解,从而分析介质的电磁性能。本文介绍了空间回路网法（SNM）的基本原理和使用方法。并计算了8 GHz平面波条件下的正方形格栅结构的反射率,通过比较发现单元尺寸为半波长时,电磁波吸收性能强于1倍波长情况。     

沟槽表面边界层湍动能分布规律

 通过对不同风速下不同尺寸V型沟槽表面及光洁平板表面边界层内湍动能的测试,对比分析了沟槽表面边界层湍动能的分布规律。试验在一小型专用风洞中开展,流场测试中使用恒温式IFA300智能型流动分析仪,测试模型则采用有机玻璃材质的矩形平板结构;而在沟槽表面理论零点及壁面摩擦速度的计算中,采用基于湍流边界层Spalding壁面律公式同时计算壁面理论零点和壁面摩擦速度的改进方法。最终研究结果表明,沟槽结构主要影响边界层流场的近壁区,沟槽的存在提高了边界层中黏性底层内湍流脉动所具有的动能,有效降低了边界层中过渡区内的湍动能,最大相对降幅超过10%,较好地验证了基于“二次涡”的沟槽表面减阻理论。     

The time delay of a solar grazing photon

Moving clocks and clocks in a gravitational field slow down, not due to the effects of special relativity nor to the space-time curvature of general relativity, but due only to the principle of equivalence and the conservation of energy. However, some might argue that there has been a further “test” of the effect of gravity on time, namely, the measurement of the time-delay of a round-trip, solar-grazing radar beacon performed by Shapiro in the 1960s. In this test, Shapiro bounced a radar pulse off Mars at superior conjunction (a feat in itself for the time), and compared the measured round-trip travel time of this pulse with the expected round-trip time of a signal traveling at c for the entire trip, as determined from highly accurate planetary ephemerides. Shapiro had predicted this time-delay long before being technologically able to make such a measurement. While general relativity can be used to correctly obtain the magnitude of this delay, it is not the only explanation. As earlier with the analysis of clocks in motion and of clocks in a gravitational field, this paper derives the same result without invoking the space-time curvature of general relativity     

涡扇发动机加力燃烧室扩压器流场的数值计算

 本文用数值计算的方法得到了某型涡扇发动机加力燃烧室扩压器内的流场,与台架状态测得的实验数据基本吻合。研究了不同进口气流参数分布对扩压器流场的影响,计算了台架不同转速状态,不同飞行工况下扩压器内的流场。     

航天器有限时间输出反馈姿态控制

研究在角速度不可测时航天器的有限时间姿态控制问题。基于有限时间控制技术,提出了由修正Rodrigues参数进行姿态描述的航天器输出反馈姿态控制算法。首先设计了单个航天器的输出反馈姿态控制器,在没有角速度反馈时也能够保证航天器姿态在有限时间内调节到期望姿态。之后,设计了无需绝对角速度和相对角速度信息的多航天器分布式输出反馈姿态控制器。使用Lyapunov理论和图论,对闭环系统全局有限时间稳定性进行了严格的证明。最后对提出的控制算法进行了数值仿真,其结果验证了所设计的航天器输出反馈控制算法的可行性和有效性。     

The Parker effect and navigation in space

The two well known rules of physics are: “The laws of interaction between solid bodies”, or Newton's Laws; and Maxwell's laws discovered in the 19th century on the laws of electromagnetic radiation, particularly its constant speed of propagation, “c”, in a vacuum. The Parker effect describes the correlation between these two rules and is at the heart of a new navigational technology called NIRPS. The Navigational Independent Relative Positioning System (NIRPS) uses the relation between an inertial medium (its own body) and a non-inertial medium (light) to provide information on the velocity (speed and direction) with which it is travelling in three-dimensional space. When the system is set in motion, the contrasts in the properties of the media result in an apparent deflection of the light. At the core of NIRPS is an a opto-electronic device called a “velometer”. The velometer measures the magnitude and angle of the Parker effect, which directly represent the speed and direction, or velocity, of the system in space. Finally, from these results we can then interpret the present position of the system relative to its previous position     

Siren(旋笛式)激励系统的气动声学特性

基于siren(旋笛式)激励系统,理论推导了旋笛产生的非定常脉动速度和双传声器法获得的声质点振动速度之间的能量转换关系,并通过系统的气动声学特性实验考察了激励强度、频率、马赫数以及传感器间距对声质点振动速度的影响,验证了理论模型.结果表明:由旋笛产生的非定常脉动速度并不完全转换为声质点振动速度,这种转换关系主要与马赫数有关.且当流体为不可压缩气体,即马赫数小于0.3时,能量转换因子与马赫数的平方成正比,马赫数越大,能量转换因子越大,非定常流动转换为声能的效率越高.      

A Velocity Estimation Algorithm of Moving Targets using Single Antenna SAR

A new algorithm is proposed for velocity estimation of moving targets in single antenna synthetic aperture radar (SAR). Based on the fact that different velocity vectors cause different geometrical figures of the two-dimensional (2-D) signature in the range-Doppler (RD) domain, this algorithm estimates the azimuth and range velocities by a 2-D search such that the range cell migration correction (RCMC) and the second range compression (SRC) are correctly performed. It is shown that, using the proposed algorithm, the Doppler ambiguity problem can be avoided and satisfactory accurate velocity estimation can be obtained in high signal-to-clutter ratio (SCR) scenarios.     

地月系L1点的月球借力间接转移轨道设计

针对地月系L1点（LL1）的轨道转移问题,在平面圆型限制性三体问题模型下,提出了利用月球借力的间接转移设计方法.转移设计分为地月转移轨道段和月球至LL1流形段.首先,通过改变LL1点初始机动速度,逆向积分LL1点的拟流形,以寻找初始速度、月心会合坐标系下的轨道高度和相位角这三者之间的关系,确定月球—LL1流形段微分改正的初始条件.然后,借助地月系不同转移时间的霍曼转移轨道所对应的近月点高度和相位角的关系,获得使2段转移在近月点相拼接的地月转移轨道段.这种设计方法给出了一系列LL1点间接转移轨道,将此设计结果与其他文献中的转移设计方法进行比较,此间接转移轨道比低能量转移轨道节省时间,比直接转移轨道节约能量.     

Alfvén Waves: Coherent Phenomena in Coronal Loops and Open-Field Regions

We analyze two situations where coherent properties of Alfvénic perturbations influence the behaviour of a turbulent system. The first case is a coronal loop where large scales are dominated by coherent fluctuations (eigenmodes) excited by resonance with motions at the loop bases. The input energy flux is mainly determined by the zero-frequency eigenmode which is independent of the background Alfvén velocity profile; the resulting scaling law gives values compatible with the flux necessary to sustain the active-region corona. Nonlinear interactions are also influenced by coherence effects. From the resulting nonlinear flux a scaling law for the velocity perturbation is derived, which is compatible with measures of nonthermal velocities in corona. In second case we studied how monochromatic Alfvén waves, propagating upward from the coronal base in a coronal hole region, develop small scales in form of a power-law spectrum when they go across a thin 3D inhomogeneous layer (～10⁴?km thick) located at the base of the corona. Though the obtained spectrum is steeper than what would be obtained by means of nonlinear interactions, it could influence the subsequent nonlinear dynamics of the system by reducing the time of heat deposition, with consequences on the acceleration of the solar wind.     

空中加油对接过程的动力学建模与仿真

空中加油的成功与否主要依赖于加油锥套与受油插头的顺利对接,对对接过程中产生的动力学行为的研究是实现顺利对接的前提。利用多刚体系统动力学建立对接过程的动力学模型,求解出加油锥套与受油装置间的广义速度;并依据建立的接触动力学模型,得到局部接触点间的相对速度。基于非线性连续碰撞理论,提出对接过程中碰撞力的计算方法,并在机械系统动力学仿真软件ADAMS的环境下,构建加油锥套和受油装置的对接虚拟样机。通过对虚拟样机的动力学仿真,得到了对接过程中的碰撞力及速度响应曲线,同时,得出能够实现成功对接时各参数的具体范围。结果表明,制约对接成功的主要参数是初始相对速度、加油锥套的俯仰角和相对偏距。该研究对空中加油的对接和受油机的导航控制具有重要的意义。     

涡轮低压导向器优化前后气动性能对比实验研究

采用实验方法对某型弹用涡扇发动机涡轮低压导向器原型和改型进行了详细的低速风洞实验。改型在原型基础上增加了多种优化措施。针对低压导向器进口前的中间机匣过渡段具有较大子午扩张角的结构特点,改型采用了等速度梯度过渡曲线来改善机匣段的扩压流动。为了减少导向器叶栅内能量损失的增长,改型采用了正弯叶片、后部加载叶型以及其它综合措施。实验结果表明,改型低压导向器的气动性能显著提高,出口总压损失比原型相对减少14.7%,出口气流角沿叶高分布较原型均匀。几种减少损失的方法得到了合理的匹配。      

模拟过载条件下EPDM绝热层烧蚀实验

用一种粒子浓度、速度和角度可调的高过载模拟烧蚀发动机,开展过载条件下粒子冲刷对EPDM绝热层烧蚀特性影响的实验研究。实验结果表明:(1)存在一个临界速度,当冲刷速度低于临界速度时,粒子浓度,速度和角度对炭化烧蚀率影响较小,而当冲刷速度高于临界速度时,炭化烧蚀率随速度的增加而急剧增加,角度影响也较大。(2)弱冲刷条件下的炭化层表面平整,而粒子沉积条件下的炭化层表面附着有很多大粒径的粒子,炭化层结构也更加疏松,而强冲刷条件下,粒子由于速度较高而不易在炭化层表面沉积。(3)当低于临界速度冲刷时,炭化层的孔隙结构分布不均匀,存在致密/疏松分层结构,而高于临界速度冲刷时,炭化层结构则更为致密。(4)通过多元回归得到了炭化烧蚀率与粒子冲刷速度,浓度和角度的经验关系式。     

用二阶矩两相湍流模型模拟鼓泡床内气泡—液体湍流两相流动

建立了二阶矩气液两相湍流模型，模拟了不同工况下二维矩形断面气液鼓泡床中气泡－液体湍流两相流动，给出了气泡和液体的速度场、气泡体积分数和两相雷诺应力分布，基本工况的模拟结果与美国俄亥俄州立大学PIV测量结果符合较好。文中研究了不同气体表观速度对两相流场的影响。模拟结果显示了鼓泡床内液体的回流流动和气泡的上升运动、各向异性的上湍流，气泡湍流脉动比液体的强，以及气泡体积分数和两相湍流强度随着气体表观速度的增大而增大等规律。     

FrFT-CSWSF:Estimating cross-range velocities of ground moving targets using multistatic synthetic aperture radar

Estimating cross-range velocity is a challenging task for space-borne synthetic aperture radar（SAR）, which is important for ground moving target indication（GMTI）. Because the velocity of a target is very small compared with that of the satellite, it is difficult to correctly estimate it using a conventional monostatic platform algorithm. To overcome this problem, a novel method employing multistatic SAR is presented in this letter. The proposed hybrid method, which is based on an extended space-time model（ESTIM） of the azimuth signal, has two steps： first, a set of finite impulse response（FIR） filter banks based on a fractional Fourier transform（FrFT） is used to separate multiple targets within a range gate; second, a cross-correlation spectrum weighted subspace fitting（CSWSF） algorithm is applied to each of the separated signals in order to estimate their respective parameters. As verified through computer simulation with the constellations of Cartwheel, Pendulum and Helix, this proposed time-frequency-subspace method effectively improves the estimation precision of the cross-range velocities of multiple targets.     

A study on turbulence transportation and modification of Spalart–Allmaras model for shock-wave/turbulent boundary layer interaction flow

It is of great significance to improve the accuracy of turbulence models in shock-wave/ boundary layer interaction flow. The relationship between the pressure gradient, as well as the shear layer, and the development of turbulent kinetic energy in impinging shock-wave/turbulent boundary layer interaction flow at Mach 2.25 is analyzed based on the data of direct numerical simulation(DNS). It is found that the turbulent kinetic energy is amplified by strong shear in the separation zone and the adverse pressure gradient near the separation point. The pressure gradient was non-dimensionalised with local density, velocity, and viscosity. Spalart–Allmaras(S–A) model is modified by introducing the non-dimensional pressure gradient into the production term of the eddy viscosity transportation equation. Simulation results show that the production and dissipation of eddy viscosity are strongly enhanced by the modification of S–A model. Compared with DNS and experimental data, the wall pressure and the wall skin friction coefficient as well as the velocity profile of the modified S–A model are obviously improved. Thus it can be concluded that the modification of S–A model with the pressure gradient can improve the predictive accuracy for simulating the shock-wave/turbulent boundary layer interaction.     

二维激光多普勒测速系统用于测量湍流分离流动

 为解决具有回流区的高湍流度分离流动的二维测量问题,研制了一种偏振分离型二维激光测速系统;测量了非对称阶跃扩张管道中湍流分离区的平均速度向量分布;得到了回流中心位置和回流区长度等参数;部分实验结果同数值模拟结果作了比较。