查询词典 probability density function

In this paper, with field experiments the allometry relationship between plant height and biomass of annual plants, Avena sativa and Vicia sativa, under low density and high density, were investigated, and the data obtained from experiments were analysed with the linear and nonlinear regression.

通过田间试验研究了两种一年生植物燕麦和箭豌豆在高密度和低密度条件下表现出来的株高与生物量之间的异速生长关系，并用线性回归和非线性回归的方法对所得数据进行了分析。

ResultsAmong 8 cases,there were low or low slightly density as in 7 cases, single high slightly density tubercle as in 1 case, following these,there were multiple neoplasm metastasis of brain other sites in 2 cases, annular shape enhancement in 3 cases after contrast CT scanning, peripheral edema lightly as in 6 cases and no in 2 cases, suprasellar region, ambiens cisterna and corpora quadrigemina were compressed, transposited and distorted differentlly,and obturated or widened locally.

结果7例脑干转移瘤呈低或略低密度影，1例单一结节为略高密度影，伴随脑内其他部位多发转移2例，3例增强扫描呈环形强化，较度水肿6例，无水肿2例，环池有不同程度受压移位、变形，以及局限性闭塞或增宽。

Whereas, the predicted results of ammoniac nitrogen degradations in case of different refuse densities display that once the refuse density is less than 535 kg/m3, the refuse density has little effect on the leachate ammoniac nitrogen degradation.(2) the diameters of leacheate collection pipes is also one of important factors to influence the leachate quality degradation.

但是，对不同压实密度的准好氧填埋场的渗滤液氨氮衰减预测显示，当压实密度小于535 kg／m~3时，其对准好氧填埋场的渗滤液氨氮降解效果影响不甚明显；(2)渗滤液收集管管径也是影响准好氧填埋场降解效果的重要因素之一。

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。

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%。

Pachomius manual labour was organized as an essential part of the monastic life; and since it is a principle of the monks as distinguished from the mendicants, that the body shall be self-supporting, external work of one sort or another has been an inevitable part of the life ever since.

根据圣pachomius体力劳动组织作为一个重要组成部分寺院生活；以来，这是一个原则的和尚，作为有别于乞丐，该机构应自支撑，对外工作的这种或那种已一个必然的一部分，生活至今。

In order to study the effects of parametrical rolling on the ship movement and tilts, in allusion to ship's navigating in regular following waves, the equation of ship rolling motion is transformed into normal Mathieu equation by proper variable replacement when strong parametrical excitation in restoring moment varied according to sine or cosine wave.

为研究参数横摇对船舶运动和倾覆的影响，通过对船在规则波上随浪航行时，恢复力矩中出现的1个以正余弦规律变化的强参数激励项进行适当的变量置换，将船舶的横摇运动方程转换成标准形式的Mathieu方程。