查询词典 average density

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。

Electronic structure of tetragonal HfO2 crystal has been calculated using localized density approximation approach of density functional theory.

采用密度泛函理论框架下的局域密度近似，计算了四方HfO2晶体的电子结构，包括能带结构和态密度。

In order to represent accurately and concisely the changing characteristics of one-dimensional spectrum density function in the chatter development. This thesis, for the first time, proposes the Edgeworth asymptotic expansion formulas of spectral density. A detailed proof is given. Some new statistic including spectral skewness, spectral kurtosis and spectral cumulants are proposed.

为了准确、简洁地表达一维谱密度函数在切削颤振建立过程中的变化特征，论文首次建立了一维谱密度函数的Edgeworth渐近谱展开式，给出了详细的证明；并由此提出了"谱偏态系数"、"谱峰态系数"和"谱累积量函数"等新的谱统计量。

Unfortunately, it has been shownthat these methods are not suitable to study about chemical bonds due to not involvingchemical bonds. In order to consider chemical bonds obviously, we have proposed an atom-bondelectronegativity equalization model on the basis of density-functionaltheory and electronegativity equalization principle. The main contents of our atom-bond electronegativity equalization model contain:(1)Considering the fact that there are varies of chemical bonds in molecules andpartitioning the molecular electron density as summations of atomic electron densitiesand chemical bond's electron densities, we obtained the basic equations of atom-bondelectronegativity equalization model: the expression of the total energy 〓, theexpression of the atom electronegativity 〓 and the expression of the bondelectronegativity 〓.

为了明确地考虑和处理分子中存在的化学键，以便能够更好地描述体系中的电荷分布进而准确地描述分子体系中的有关物理化学性质，尤其是与化学键有关的物理化学性质，我们在密度泛函理论和电负性均衡原理基础上提出了原子-键电负性均衡模型，原子-键电负性均衡模型的主要内容是：(1)考虑到分子体系中存在各种化学键这个事实，将分子空间看成是由原子区和化学键区组成的，将分子的单电子密度表达成为分子中各组成原子的单电子密度和各化学键的单电子密度的加和，从而得到了原子-键电负性均衡模型的基本方程：分子体系总能量〓和分子中原子电负性〓和化学键电负性〓表达式。

In this paper, quantum theory, the use of time evolution operator obtained by the first method for the system density operator of any time, and atomic reduced density matrix, and the atomic dipole squeezing conditions, numerical study of the mixed state -type atom of the three-level with single-mode optical field coherent interaction of atomic dipole squeezing effect.

本文采用全量子理论，运用时间演化算符方法先求出所求系统任意时刻的密度算符，和原子的约化密度矩阵，以及原子偶极压缩的条件，数值计算地研究了混合态型3能级与单模相干光场相互作用时原子的偶极压缩效应。

In particular, the atomic density distribution along the long axis of the nanowire was transformed into a amplitude-frequency relation or into a normalized atomic density distribution.

通过转换实空间的原子密度分布函数，得到振幅－频率图和归一化的长轴原子密度分布图。

Density weighted harmonic averaging middle operator; argument clustering; density weighted vector; aggregation

从密度加权平均中间算子（文中式（3））和密度加权几何平均中间算子的（文中式（4））的形式与平均数的形式进行对比，很容易得到密度加权调和平均中间算子（文中式（7））。

The results indicate that back electromotive force increases with increasing current density and decreases by 0.5 V after adding 2% Li2CO3, the feeding period is 15 min measured by the method of electric potential control. Finally, the Al-Li alloy with the lithium content of 7.93% can be obtained by electrolyzing for 3 h at the current density of 0.62 A/cm^2 and at 680 ℃, and the current efficiency can reach 74.1%.

结果表明，反电动势随电流密度增加而增大，加入2%的Li2CO3可使反电动势降低0.5V；通过控制电位法测得加料周期为15 min：在680℃、电流密度为0.62A/平方公分的条件下持续电解3h，最终制得了理含量高达7.93%的铝锉合金，电流效率可达74.1%。

Aiming at the problems existed in the traditional experimental study and analytic methods in theory while the study was underway by the high density baler directly in laboratory, computer analysis and simulation on compressing hay in high density baler are accomplished according to the technology idea in modem design theory. The virtual prototype technology is introduced in the research.

针对在试验室条件下直接利用高密度压捆机对牧草高密度压缩过程进行研究时，传统的试验研究和理论分析方法存在的问题，本文根据现代设计理论中提出的技术思想，对牧草的高密度压捆过程进行了计算机分析与仿真研究。

ADAMS is used as an instrument to analyze the process of compressing hay in high density baler. A ADAMS model of the compressing hay in high density baler is established, and the modeling method and model structure are validated by ADAMS.

在研究中，引入了虚拟样机技术，使用ADAMS软件对牧草的高密度压捆过程进行分析，建立压缩过程中牧草的ADAMS模型，并对ADAMS的建模方式、模型结构进行了验证。

"Second Life is remarkably easy to work with, and is very popular,"

"第二次生命是显着容易的工作，并且很受欢迎，"

For example, we usually assume that materials are homogeneous and isotropic and free of internal defects or flaws.

为了得到适合有限元分析的模型，我们必须经过如图2所示的简化步骤。