雷达目标角闪烁计算方法研究

详细描述了雷达目标角闪烁的3种计算方法,通过一简单的计算实例说明这3种算法的统一性。分析了各算法的优缺点,就各种算法的计算前提进行了说明。指出当没有确切相位、极化信息时采用矢量和成较为简单;当存在相位信息而不知道极化时,采用相位梯度法较为合适;当辐射源所有信息都知道时,采用波印庭矢量法最为合适。最后举例说明相位、极化对目标回波方位的影响。     

Revisiting the Fundamental Nature of Metal-Ligand Bonding: An Impartial and Automated Fitting Procedure for Angular Overlap Model Parameters

The properties and reactivities of transition metal complexes are often discussed in terms of Ligand Field Theory (LFT), and with ab initio LFT a direct connection to quantum chemical wavefunctions was recently established. The Angular Overlap Model (AOM) is a widely used, ligand-specific parameterization scheme of the ligand field splitting that has, however, been restricted by the availability and resolution of experimental data. Using ab initio LFT, we present here a generalised, symmetry-independent and automated fitting procedure for AOM parameters that is even applicable to formally underdetermined or experimentally inaccessible systems. This method allows quantitative evaluations of assumptions commonly made in AOM applications, for example, transferability or the relative magnitudes of AOM parameters, and the response of the ligand field to structural or electronic changes. A two-dimensional spectrochemical series of tetrahedral halido metalates ([M^IIX₄]²⁻, M=Mn−Cu) served as a case study. A previously unknown linear relationship between the halide ligands’ chemical hardness and their AOM parameters was found. The impartial and automated procedure for identifying AOM parameters introduced here can be used to systematically improve our understanding of ligand–metal interactions in coordination complexes.     

惯性平台中成对角接触球轴承的应用与研究

惯性平台是通过轴承将台体组件、内框组件、外框组件联系起来的，是在具有振动、冲击、摇摆的环境下工作的。为了保证平台系统的精度，对轴承的参数指标要求比较高。文中通过分析和计算提出了方法和建议，为以后的轴承改进和设计奠定了基础。     

Dynamic Contact Behavior of a Golf Ball during Oblique Impact: Effect of Friction between the Ball and Target

The oblique impact between a golf ball and a polymethyl methacrylate (PMMA) target with smooth transparent surfaces was studied using a high-speed video camera. Video images of the impact were recorded from the backside of the target and were used to determine the contact time, contact area, and the displacement and rotation of the ball along the target. The average tangential and angular velocities were determined as functions of the inbound ball velocity. As the inbound ball velocity increased, the contact area and average tangential and angular velocities also increased while the contact time decreased. An oiled PMMA target was used to study the effect of reduced friction between the ball and target. The results were compared with earlier data for a steel target with relatively rough surfaces. The contact area and time were unaffected by friction, but the average tangential velocity increased while the average angular velocity decreased as the friction decreased.     

Shared aperture metasurface antenna for electromagnetic vortices generation with different topological charges

Vortex beams carrying orbital angular momentum (OAM) have aroused great interest of both scientific and engineering communities. Encouragingly, generating OAM with different topological charges in a shared aperture is regarded as a potential route to expanding the communication capacity, which yet is an academic challenging task. In this work, a paradigm of designing metasurface-based shared aperture antenna for generating polarization-dependent vortex beams with distinct topological charges is proposed. Anisotropic unit cells that can tailor different resonance phase profiles in two orthogonal orientations are used to assemble a metasurface reflector. As a proof-of-concept, a planar reflector antenna is designed with two Vivaldi sources, which can generate x- and y-polarized vortex beams with topological charges of l=-1 and l=-2, respectively. Both the simulation results and the measurement results are in good agreement, which demonstrates the feasibility of our design. Significantly, this work provides a new route to achieving vortex beams carrying different topological charges in the same frequency band, which may have potential applications in communication systems.     

Photofragment Imaging of HNCO Decomposition at 210 nm: the Primary NH(a1￠)+CO(X1§+) Channel

The photodissociation of isocyanic acid (HNCO) on the ˉrst excited singlet state following the excitation at 210 nm was investigated with an ion velocity slice imaging technique by probing the CO fragment. It was found from the (2+1) resonance-enhanced multi-photon ionization (REMPI) spectrum that the CO fragments are rotationally hot with population up to Jmax=50. The velocity imagings of the CO fragments at JCO=30 and 35 indicate that formation of NH(a1￠)+CO(X1§+, v=0) is the predominant dissociation channel at 210 nm. From analysis of the CO fragment translational energy distributions, the NH(a1￠) fragment was observed to be rotationally cold, about half of the available energy was partitioned into the translational motion of fragments after dissociation, and the NH(a1￠)+CO(X1§+) dissociation threshold was determined at 42738§30 cm?1. From analysis of the CO fragment angular distributions, the dissociationanisotropy parameter ˉ was found to be negative, and increasing with the rotational quantum number of the NH fragment, i.e., from ?0.75 at JNH=2-4 to ?0.17 at JNH=11. Impulsive direct and vertical dissociation process of HNCO on the singlet state at 210 nm was conˉrmed experimentally. A classical impact dissociation model was employed to explain the dependence of the ˉ value on the rotational excitation of the NH fragment.     

Global Weak Solutions to Equations of Motion for Magnetic Fluids

We study the differential system governing the flow of an incompressible ferrofluid under the action of a magnetic field. The system consists of the Navier–Stokes equations, the angular momentum equation, the magnetization equation, and the magnetostatic equations. We prove, by using the Galerkin method, a global in time existence of weak solutions with finite energy of an initial boundary-value problem and establish the long-time behavior of such solutions. The main difficulty is due to the singularity of the gradient magnetic force.      

Influence of angular momentum on evaporation residue cross section as a probe of nuclear dissipation

By calculating the excess of the evaporation residue cross sections of the 200pb nucleus over that predicted by the standard statistical model as a function of nuclear viscosity coefficient using a Langevin equation combined with a statistical decay model, it is found that high angular momentum not only amplifies the dissipation effects on the excess of the evaporation residue cross sections, but also considerably increases the sensitivity of this excess to the nuclear viscosity coefficient. These results suggest that on the experimental side, to accurately obtain the information of nuclear dissipation inside the saddle point by measuring the evaporation residue cross section, it had better populate those compound systems with high spins.     

18O+148Nd的准弹性碰撞研究和耦合道分析

用Q3D磁谱仪及其焦面探测器系统,在90.72MeV处测量了¹⁸O+¹⁴⁸Nd的弹性散射和非弹性散射角分布,利用DWBA和耦合反应道计算程序FRESCO,对实验结果进行了拟合.在对弹性散射分析中,引入极化势的DWBA计算与耦合道计算有类似的结果.讨论了非弹性散射激发过程中的核–库仑激发的相干效应,得出了描述相干强度的近似因子.     

A Microcomputer System for Automatic Mode Sweep of Ring Laser Angular Rate Sensor (Ring Laser Gyro)

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