查询词典 direction field

It put forward some method to improve efficiency of devices from donor and acceptor side and point out the direction of ahead in this field.

并从聚合物太阳能电池的给体相和受体相两方面着手，提出了改善此类电池的一些途径，探讨了该研究领域发展的方向。

It is concluded that when a small solid angles range adjacent to the main direction in the far field is considered, the parallel beams combining of compact antenna arrays has its priority if the phases can be controlled, and the parallel beams combining of sparse antenna arrays has its priority if the phases can not be controlled.

分析表明：当关注的是远区主方向邻近的小立体角区域时，若能做到控相激励，宜采用紧凑阵的平行波束合成；若不能控相，宜采用稀疏阵的平行波束合成。

A novel direction of arrival and polarization estimation of electromagnetic vector sensors mounted on the airframe is proposed based on biquaternion. The signal processing model for EM-sensor mounted on the airframe is made by biquaternion and then the eigenvalue decomposition of spectral matrix is obtained by means of the EVD of its quaternion adjoint matrix. The memory requirement for data is reduced, and more accurate estimation result is gotten by deducing the stronger orthogonality constraint between the sin- gal and noise subspaces on the field of biquaternion. The performance of the new algorithm is confirmed through numerical examples.

针对机载电磁矢量传感器阵列DOA和极化参数估计问题，提出了一种基于复四元数估计方法，该算法利用四元数建立机载电磁矢量传感器阵列信号处理模型，然后利用四元数联合矩阵的特征分解得到阵列数据相关矩阵的特征分解，一方面使得计算过程中数据的贮存量大大减少，另一方面通过推导得到信号子空间和噪声子空间在四元数域上的正交性从而使DOA和极化参数佑计的精度更高，仿真证实了本算法的有效性。

This thesis contributed to the comprehensive study of the Finite-Difference Time-Domain method and its application to the numerical computation of radiated electromagnetic fields in switched mode power supplies. The work includes mainly three parts: the study on the performance of PML absorbing boundary condition applied to pseudo low frequency electromagnetic problems; the validation of the FDTD method with PML absorbing boundary conditions and the corresponding computer software based on the numerical study of the electromagnetic field of an electric dipole antenna, and its application to the numerical computation of radiated electromagnetic fields in switched mode power supplies; the development of an improved alternating direction implicit finite-difference time-domain method.

在综合前人工作基础上，本文对时域有限差分法及其在开关电源辐射电磁场数值计算中的应用进行了系统的分析和研究，其核心内容包括：伪低频电磁场数值计算中PML吸收边界条件性能的研究；基于基准问题—电偶极子天线三维辐射电磁场，验证了本文构造的基于PML吸收边界条件的三维FDTD法及其计算软件，并应用于高频开关电源辐射电磁场的数值分析；提出了一种改进的交替方向隐格式时域有限差分法。

An iterative temperature field model of cylinder, in which the non-linear steam temperature distributed along axial direction, was got based on two-dimensional transient heat conduction differential equation. Analytical simulation demonstrates not only a rapid solution convergence but a minor error.

在二维圆筒壁非稳态导热的基础上，得到了圆筒壁内蒸汽沿轴向线性分布，随时间非线性变化的温度场迭代计算公式，并与有限元计算结果作了对比，结果表明所得模型计算精度高、计算速度快。

Shadow effect can not be neglected for thermal analysis of spacecraft,Accroding to the angle between solar light and antenna orbit plane and its orbit location,analytical geometry method was used for accurately calculating solar radiation heat flux distribution of reflector surfaces.To analyze the temperature field under heat flux,the formulations of net radiation flux density between two gray elements and the net flux density of gray surface under external thermal flux were deduced.Based on the characteristic of space environment,the nonlinear temperature distribution in transverse direction of reflector shell self radiation were considered,the finite element formulations were given for orthogonal material layered shell by Galerkin method.A layered element including a inner heat source layer was proposed,and the finite element formulation expressed by DOF of the inner heat source layer were put forward with temperature and heat flux boundarys between adjacent layer.

单馈反射面赋形天线是未来星载天线发展的一个重要形式，分析了基于物理光学、几何光学和几何绕射理论的理想反射面辐射场；介绍了基于几何光学的反射面天线赋形方法；针对赋形过程中辐射场的快速分析要求，比较分析了基于物理光学的Fourier-Bessel和Jacobi-Bessel级数展开方法以及GB展开分析方法；利用GB展开快速分析方法在20GHz频率下对0.6m口径的天线进行赋形分析，实现中国大陆的30dB增益覆盖，通过数值计算研究了固定增益期望下的口径尺寸随频率的变化，以及频率为20GHz的不同尺寸天线赋形后的覆盖目标区域最大增益的变化情况。

An initial current sheet separates the simulation domain with antiparallel magnetic field components in the x direction.

初始电流片将在x方向上具有反平行磁场分量的模拟区域分成两部分。

In a low magnetizing field the coercivity of the non-aligned magnet is higher than that of the aligned magnet; the coercivity of the sample magnetized antiparallel to the aligned direction...

低场时非取向样品比取向样品的矫顽力大，外场反平行于取向方向比平行于取向方向的矫顽力大，而在足够大的外场下二者趋于相等。

The continuous ultraviolet laser with 351 nm wavelength was focused on the -z surface of nearlystoichiometric LiTaO3, and the homogeneous electric field which was antiparallel to the direction of spontaneous polarization was applied simultaneously.

波长为351nm的连续紫外激光被聚焦在近化学计量比钽酸锂晶体的-z表面，同时沿与晶体自发极化相反的方向施加均匀外电场。

The continuous ultraviolet laser with 351 nm wavelength was focused on the -z surface of nearly-stoichiometric LiTaO3, and the homogeneous electric field which was antiparallel to the direction of spontaneous polarization was applied simultaneously.

波长为351 nm的连续紫外激光被聚焦在近化学计量比钽酸锂晶体的-z表面，同时沿与晶体自发极化相反的方向施加均匀外电场。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。