孔径

The maximum entropy method is adopted to extrapolate data,and ISAR image is obtained based on this.

利用最大熵谱估计的方法对四种飞机目标数据进行外推处理，并在此基础上进行逆合成孔径成像。

Furthermore , maximum stress of casing of perforation cement hoop generates from eyehole and declines along pore diameter direction .

射孔水泥环套管最大应力在射孔孔眼产生，沿孔径方向应力减小。

The diameter of such an opening, often expressed as an f-number.

孔径这种开口的直径，常以f数表示

The lens system adopted the Reverse-Telephoto configuration which had an effective focal length of 5.5mm,an F-number of F/4 ,a field of view of 175°,and a working wavelength in the range of visible spectrum.

系统焦距为5.5mm，相对孔径为1/4，全视场角175°，光谱范围为可见光波段，采用了3组10片的反远距型结构。

F-number: The figures marked on the lens collar to indicate the size of the lens aperture in relation to its focal length.

光圈值：刻划在镜头上用来表示镜头孔径与焦距关系的比值。

This paper presented an optical system of star sensor. The lens system was a complicated double- Gauss configuration which had an effective focal length of 51 mm, an F-number of F/1.1, a field of view of 21°×21°(2ω=30°),and a working wavelength rang of 0.5~0.85 μm.

介绍了一种用于卫星姿态控制的星敏感器光学系统，该光学系统焦距为51 mm，相对孔径为1/1.1，视场角为21°×21°（圆视场2ω＝30°），光谱范围为0.5～0.85 μm，采用了复杂化双高斯结构。

A R-C system with foci of 2 m and f-number F/4 was taken for an example, the principles of stray light eliminating and evalutiong in reflective optical system was put forward. Lens hood in the main mirror, lens hood outside and window shade, lens hood in the secondly mirror were designed by CAD modeling.

以焦距为2 m，相对孔径为1/4的R-C系统为例，介绍了利用计算机仿真技术进行消杂散光设计和评价的原理，结合CAD建模进行了主镜内遮光罩、外遮光筒、次镜百叶窗式遮光罩的设计。

In my study, we use a 4F acoustic lens which f-number is 1.3 to set up a photoacoustic imaging system. With same axial and lateral magnification, 3D photoacoustic imaging system with 4F acoustic lens can detect photoacoustic signal distribution on object plane in real-time, and get the different axial distance signal to show the 3D photoacoustic image by different signal receiving time.

本研究采用相对孔径为1.3的4F声透镜，设计三维光声影像系统，利用4F声透镜景深范围内之轴向与横向放大倍率相等，即时性的重现物平面所发出的同调性光声讯号分布，并利用不同的接收时间来呈现不同深度距离的讯号成像，取得物平面上受测物的三维光声影像。

XRD and TEM confirmed that the novel mesoporous silica has a diamonded face centered cubic structure with Fd3m symmetry, which was first reported up to date.

同时对它的物理性能包括比表面积、孔容和孔径通过N〓吸附-脱附技术进行了测定，考察了合成条件对其结构形成的影响。

It showed that the energy focusability of the diffraction beam depended on the transmission distance,diffraction aperture and facula radius,and appropriate energy focusability could be obtained by controlling some parameters of the optical system.

研究结果表明，衍射光束的能量集中度与传输距离、衍射孔径、光斑半径等参量有关，通过对光学系统参量的控制，可得到合适的能量集中度。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了