FAIR项目Super-FRS超导二极磁铁端部优化

介绍了Super-FRS超导二极磁铁的磁场优化和端部削斜方案,采用OPERA软件对活极头进行削斜计算,得出合理的活极头尺寸,使各场下的积分均匀度在要求范围内达到了±2×10-4。最后将计算的积分场均匀度与磁场测量的结果进行比较,结果吻合得较好,验证了这种端部活极头优化计算方法的正确性。 The end optimization of dipole magnet of Super-FRS for FAIR by OPERA 3D has been introduced in this paper. By using a complicated chamfer, the integral field homogeneity which is better than 2×10-4 can be obtained. In addition, the paper also introduced the comparison between the magnetic field measurement result and calculation one, which confirms the method of the removable pole end chamfer very well.     

CSNS/RCS交流二极磁铁研制关键技术

针对交流二极磁铁的磁场特性和涡流问题,利用电磁场分析软件对磁铁进行了优化设计和温度场计算,确定了交流二极磁铁关键技术的方案。对交流二极磁铁极头端面采用了罗高斯基曲线和谐波削斜的方法来提高磁铁磁场质量;对铁芯端部和端板进行开槽优化设计,有效切断磁铁端部主要的涡流回路,降低了磁铁温升;磁铁线圈采用铝绞线导线进行绕制,以减少磁铁线圈内的涡流损耗。最后,通过对样机磁铁的测试,磁场均满足物理要求,磁铁温度也控制在安全范围内。     

Effective medium representation and complex modes in 3D periodic metamaterials made of cubic resonators with large permittivity at mid-infrared frequencies

We review some of the techniques that lead to the effective medium representation of a three-dimensional (3D) periodic metamaterial. We consider a 3D lattice of lead telluride cubic resonators at mid-infrared (MIR) frequencies. Each cubic resonator is modeled with both an electric and a magnetic dipole, through a method called the dual dipole approximation. The electric and magnetic polarizabilities of a cubic resonator are computed via full-wave simulations by mapping the resonator's scattered field under electric/magnetic excitation only to the field radiated by an equivalent electric/magnetic dipole. We then analyze the allowed modes in the lattice, with transverse polarization and complex wavenumber, highlighting the attenuation that each mode experiences after one free space wavelength. We observe the presence of two modes with low attenuation constant, dominant in different frequency ranges, able to propagate inside the lattice: this allows the treatment of the metamaterial as a homogeneous material with effective parameters, evaluated by using various techniques. We then show that the metamaterial under analysis allows for the generation of artificial magnetism (i.e., relative effective permeability different than unity, including negative permeability with low losses) at MIR frequencies.     

基于椭圆型方程的扭叶片造型方法的研究

本文以偏微分方程造型为基础,提出了一种基于椭圆型方程的扭叶片三维型面直接设计方法,详细推导了叶型曲面函数,给出了型面方程的求解及其前后缘修正。该方法具有设计叶型曲面自然光顺,设计参数少且各参数具有明显的几何意义,叶型曲面调整方便,利于采用非数值优化算法对其进行气动优化等优点。文中给出了设计实例,并通过数值实验分析了所设计叶片型面的流动特性。分析结果表明设计叶片具有良好的气动性能,同时也证明了本文提出的基于椭圆型方程的扭叶片三维型面设计方法的可靠性和实用性。     

3D computational method to study the focal laws of transducer arrays for NDE applications

Based on the impulse response and the discrete representation methods, a 3D computational method has been developed to calculate the optimal focal laws to focus the ultrasonic beams through interfaces of complex geometry, and the respective transmitted ultrasonic field generated by NDE transducer arrays. 1- and 2D array transducers are considered. Two different focusing techniques are used to obtain the time delays: the first travel time on each center of the array element, and the cross correlation between the simulated signals from neighboring array elements. Applying the time delays to the array, the transmitted field can be simulated using the same computational method. Several simulations were performed to present the ability of the computational method to focus through, for instance, curved and plane surfaces between two media (acrylic-steel). A comparison between the two focusing techniques is presented.     

复杂背景下彩色数字图像分割算法研究

为了提高复杂背景下彩色数字图像分割的准确率,减少噪声对图像处理的干扰,尽可能的缩短运行时间,需要对复杂背景下彩色数字图像分割算法进行研究。当前图像分割算法在彩色数字图像分割的过程中,仅仅考虑了图像像素的亮度值,没有考虑其空间特征,存在计算的复杂性过大等缺陷,影响彩色数字图像处理效果。为此,提出了一种基于随机权重粒子群的复杂背景下彩色数字图像分割算法。该算法先采用多尺度均匀滤波方法,对复杂背景下彩色数据图像进行划分,其中包含噪声和不含噪声的像素点的亮度值、结构元素以及局部区域内的图像像素加权亮度密度特征。采用多段图分割获取彩色数字图像的优化分割,在平滑项中代入彩色数字图像梯度信息,对彩色数字图像分割结果中的弱边界进行剔除,从而实现准确的彩色数字图像分割。实验仿真证明,所提算法增加了彩色数字图像分割的对比度和信噪比,提高了复杂背景下彩色数字图像分割的准确性。     

Vortex structures with complex points singularities in two-dimensional Euler equations. New exact solutions

In this work we present a new class of exact stationary solutions for two-dimensional (2D) Euler equations. Unlike already known solutions, the new ones contain complex singularities. We consider point singularities which have a vector field index greater than 1 as complex. For example, the dipole singularity is complex because its index is equal to 2. We present in explicit form a large class of exact localized stationary solutions for 2D Euler equations with a singularity whose index is equal to 3. The solutions obtained are expressed in terms of elementary functions. These solutions represent a complex singularity point surrounded by a vortex satellite structure. We also discuss the motion equation of singularities and conditions for singularity point stationarity which provide the stationarity of the complex vortex configuration.     

Møller’s Energy-Momentum Complex for a Spacetime Geometry on a Noncommutative Curved D3-Brane

Møller’s energy-momentum complex is employed in order to determine the energy and momentum distributions for a spacetime described by a “generalized Schwarzschild” geometry in (3+1)-dimensions on a noncommutative curved D3-brane in an effective, open bosonic string theory. The geometry considered is obtained by an effective theory of gravity coupled with a nonlinear electromagnetic field and depends only on the generalized (effective) mass and charge which incorporate corrections of first order in the noncommutativity parameter.     

用杂化CIS-DFT方法研究外电场对乙烯激发态的影响

采用杂化CIS-DFT方法研究了外电场对乙烯分子基态和激发态性质的影响，结果表明外电场对分子几何结构，总能量，偶极矩，极化率，振子强度和激发能有显著影响。CIS-DFT的优点在于它能确定外场下分子的对称性并且给出正确的激发顺序以及分子轨道的电子组态，由此导出乙烯分子的激发态，计算结果与实验一致。首次研究了乙烯分子的外电场效应。与其他从头算方法相比，杂化CIS-DFT方法计算精度和效率相对较高，可用于研究大分子体系。     

New method for measuring diesel nozzle orif ice inlet structures based on synchrotron X-ray tomography

Spray behavior is regarded as one of the main factors influencing engine performances, fuel consumption and emissions for diesel engines. Under high injection pressure, diesel spray behaviors are extremely sensitive to the nozzle internal geometries, especially the geometric structures of orifice entrance. Based on the synchrotron radiation X-ray tomography technique, the 3D digital models of nozzle tips can be constructed. A new automatic method is presented to reveal the inlet structures according to these nozzle orifice models. The planes passing through the orifice axis are determined and used to cut the models, and then the corresponding cutting images are applied to measure the inlet chamfer radii around the orifice axis automatically. The orifices of a single-hole nozzle and an eight-hole nozzle are measured according to this method. The results show that this method can automatically measure the orifice inlet chamfer radii around the orifice axis with high precision. The obtained inlet chamfer radius shows the whole profile of the orifice entrance, which is a precise feedback for nozzle designing and manufacturing, and it also provides precise geometrical boundary conditions for the study of spray behaviors.     

Scaling Design and Experimental Study on Hall Thrusters with Curved Magnetic Field

The existing scaling theories of Hall thrusters are based on the hypothesis of a one‐dimensional straight magnetic field, which is not suitable for the design of modern thrusters with a two‐dimensional curved magnetic field. In this paper, using the equation analysis method, we derive new similarity criterions in a curved magnetic field by analyzing the momentum equations of charged particles; consequently, we propose a new modeling design method for Hall thrusters with a constant discharge voltage. This method is further validated by experiments. A designed model with a power of 1.5 kW is made based on our proposed method from a prototype model with a power of 1 kW. The experimental results demonstrate that these two thrusters have little differences in performance and physical processes as expected from the scaling. Therefore, our method is well suited for designing a Hall thruster with a curved magnetic field (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Gravitational Effects in Electrostatic Storage Rings and the Search for the Electric Dipole Moments of Charged Particles

Journal of Experimental and Theoretical Physics - Spurious signals induced by curved spacetime in the gravity field of the rotating Earth in experiments on the search for the electric dipole moment...     

内置垫补线圈的C型二极磁铁

对HIRFL CSR的原形磁铁进行了试制和研究.尝试了一种新的改善磁场分布的方法:在不增大极头的条件下使用两根内置导线,实践证明是可行的.用OPERA 2D和TOSCA 3D软件分析了垫补电流对中、低场的影响,同时也介绍了这块C型二极磁铁的制作工艺及磁场测量结果. The C-type dipole prototypes in the injection beam line from a Separate Sector Cyclotron (SSC) to Cooling Storage Ring (CSR) are selected as R & D for CSR magnets fabrication, because they have large bending angle and small radius, and are very difficult to stack and fabricate. A method to obtain good field homogeneity has been attempted in the C-type dipole prototype. This method is not the enlarged dipole pole but two imbedded conductors and two small power supplies. This is easy operating....     

外电场对2-氟-5-溴吡啶分子结构与电子光谱影响的研究

采用密度泛函B3LYP方法,在6-311++g(3df,3pd)基组水平上优化了不同外电场下2-氟-5-溴吡啶分子的基态稳定构型、电偶极矩和分子的总能量,在此基础上利用杂化CIS方法研究了外电场下2-氟-5-溴吡啶分子的前9个激发态的激发能、波长和振子强度受外电场的影响规律.结果表明:5C-9Br和3C-10F间键长受到X轴向外场影响最大,随着外电场的继续增加,可能最先趋于断裂;在外电场F=-0.05 a.u.时总能量达到最大,而偶极矩达到最小;LUMO能级受外场影响较大,HOMO能级受外电场影响较小;激发波长、振子强度也受外电场影响,但随电场变化比较复杂.     

外电场对2-氟-5-溴吡啶分子结构与电子光谱影响的研究

采用密度泛函B3LYP方法，在6-311++g(3df,3pd)基组水平上优化了不同外电场下2-氟-5-溴吡啶分子的基态稳定构型、电偶极矩和分子的总能量，在此基础上利用杂化CIS方法研究了外电场下2-氟-5-溴吡啶分子的前9个激发态的激发能、波长和振子强度受外电场的影响规律。结果表明：5C-9Br和3C-10F间键长受到X轴向外场影响最大，随着外电场的继续增加，可能最先趋于断裂；在外电场F=-0.005a.u.时总能量达到最大，而偶极矩达到最小；LUMO能级受外场影响较大，HOMO能级受外电场影响较小；激发波长、振子强度也受外电场影响，但随电场变化比较复杂。     

The Electric Dipole Moment of the CO2–CO van der Waals Complex

Radiofrequency transitions withinK= 2 asymmetry doublets have been observed for the CO₂–CO van der Waals complex. A Stark effect measurement on theJ= 2,K= 2 transition provides an electric dipole moment of μ = 0.2493(1) D. Combining this result with the permanent moment of CO, μ_CO= 0.1098 D, gives a change of moment on complex formation of Δμ = 0.140 D. The sign of Δμ is such that the CO end of the complex is more positive than CO₂. The origin of Δμ should not be attributed to any single mechanism, and several different contributions to Δμ are discussed.     

The diffraction of radio waves by the curvature of the earth

This paper gives a simplified approximate derivation of the field at moderate heights and distances due to an oscillating electric dipole at moderate height above the earth, taking into account the curvature and electrical constants of the earth. The method applies to both vertically and horizontally polarized waves. It is closely connected with treating the earth as flat, the propagation of the waves being curved upwards. In this way the expansions in Legendre functions can be replaced by Fourier integrals, which are simpler to handle. The results of previous workers are reproduced, but are obtained more directly in a form suitable for easy computation.     

基于邻井反射的偶极横波远探测验证方法

偶极横波远探测技术已成为探测井外地质构造的一种重要测井技术,需要针对偶极横波远探测的验证迫在眉睫。本文利用三维有限差分数值模拟方法,对比和分析了地层界面和相邻充液邻井产生的反射横波幅值的差别,结合现场实例,提出了偶极横波远探测成像测井的验证方法。在此基础之上,进一步分析了不同反射邻井结构时,反射横波幅度的变化情况,结果表明,采用多井联合方式可以有效的增加反射波的幅值,减小非共面产生的散射效应影响。最后,初步建立了两口试验井,测试数据处理结果与理论分析结果吻合,为下一步实验井方案的优选和完善提供了理论和数据支持。     

Damping characteristics of elastic-viscoelastic composite curved bars and helical springs

The paper deals with the analysts of damping characteristics of a curved composite shaft. The composite shaft consists of an outer elastic curved tube with a similarly curved rod placed inside. The annular space between the tube and the rod is filled with viscoelastic material. The composite shaft is clamped at one end and a concentrated load (varying harmonically) acts on a radial arm fixed to the outer shell at the free end. It is shown that optimum design values exist for maximizing the total damping capacity of the system. It also is indicated that direct use of this method for increasing the damping capacity is not effective, as the damping factor reduces sharply after reaching a maximum value. It is shown how this difficulty can be overcome and how helical springs, possessing considerable damping capacity, can be designed. Sometimes this may help in simplifying the design of vibration isolators which will take the shape of a simple spring only.