群速度

The designated verifier signature scheme was proposed using the root problem and conjugacy search problem in the braid group. Analysis shows that it is a simple, fast and efficient scheme with security features.

介绍了辫群的基本概念和辫群中的困难问题，在此基础之上，利用辫群中左右子群的元素可交换性，提出了一个基于辫群上的共轭查找问题和p次根问题的指定验证者的签名方案，通过分析可知，该方案具有简单实用、算法速度快和高效安全的特性。

The new algorithm effectively combines the advantages of ACO and PSO. It adopts the grid method for environment modeling and makes use of the efficiency and succinctness of PSO to obtain the initial distribution of pheromone, reducing the number of iterations and accelerating the convergence. At the same time, by using the parallelizability of ants and distributed parallelized-searching technology, the performance of the algorithm is effectively improved.

该方法有效地结合了粒子群算法和蚁群算法的优点，采用栅格法进行环境建模，利用粒子群算法的快速简洁等特点得到蚁群算法初始信息素分布，以减少迭代次数，加快算法的收敛速度；同时利用蚁群算法之间的可并行性，采用分布式技术实现蚂蚁之间的并行搜索，求解精度高等优点，求精确解。

Meaningful chunk reading refers to a way of reading in which a saccade is done on a basis of a meaningful phrase and the meaning of what is read is acquired directly from the print.

视幅所扫视的意群组块的大小、从意群直接求义的速度与阅读过程在线建构一整合意义的速度，都直接影响阅读速度。

No entire nitrendipine crystals were observed visually in SEM photos. The results of X-ray diffraction and differential scanning calorimetry analysis indicated that the crystalline form of nitrendipine was highly dispersed in microspheres, so as amorphous state. The drug release rate of microspheres could be controlled with adjusting the ratio of solid dispersion carriers and retarding agents formulated. The agitation speed and temperature of the preparation process have distinct effect on micromeritic properties of microspheres. The release profiles of the microspheres were mainly affected by the stirring rate of paddle, the concentration of SDS and pH of dissolution medium. Cooling speed and time, however, have no evident influence on the drug release rate of the microspheres. The dissolution data showed that the mechanism of drug release from microsphers was mainly diffusion-controlled. The incorporation efficiencies of 3 batches sample were exceed 96. 8％, which implied that the current method was suitable for design sustained-release dosage form for poorly water-soluble drug.

在扫描电子显微镜下观察，在微球内外未发现尼群地平的完整结晶，X-射线粉末衍射和差示扫描量热试验结果也显示，尼群地平已经被高度分散在微球中；微球的释药速度可通过调整处方中固体分散体载体和阻滞剂的比例控制；制备温度和搅拌速度对微球的质量影响较大；溶出仪的搅拌速度，释放介质的浓度和pH对微球的释放有较大的影响；制备过程中的冷却速度和冷却时间对微球的释放行为影响不很明显；方程拟合的结果表明缓释微球的释药行为符合扩散机制；测定三批微球样品的包封率均在96.8％以上，表明该法适合于制备难溶性药物的缓释微球。

A circle is placed at the launch point to improve the interaction between the electron beam and the fields supported by the slow wave structure, thus to control the beam current density at the launch point, and to minimize the loss of the electron beam energy. The inaner radii of the extractor vanes are slightly larger than those of other SWS vanes, which increases the axial group velocity and enhances the microwave output power and efficiency. Implementation of two RF choke vanes stops the leakage of microwave pulse power toward the diode, and makes the device more compact than the conventional MILO.

该振荡器在阴极电子发射起点加圆环，控制此处电子束的发射密度，来减少电子能量的损耗，改善束－波互作用；逐渐加大慢波结构的后两个叶片的内半径，增大微波群速度，便于谐振腔中的能量输出，提高微波输出效率；采用两个扼流片有效地阻止了微波功率向二极管区泄漏，相应减小了器件的尺寸。

The results showed that the effect of group velocity dispersion on the pulse with large chip was slight and the effect of spectral width on the self-focusing properties could be ignored.

研究结果表明，群速度色散对大啁啾脉冲的影响很小，谱宽对自聚集的影响可以忽略。

Base on the analysis, the interface between a nonlinear lefthanded material and a righthanded material can support both forward TE surface waves and backward TE surface waves under certain conditions.

针对电磁波在非线性左手系材料中的传播性质，分别研究了左、右手系材料界面以及两左手系材料界面上非线性TE表面波的传播行为讨论了导波的频率特性、色散关系以及群速度随频率的变化规律分析表明，两种界面上的非线性TE表面波均存在频率通带和禁带，且带宽是传播功率的函数揭示了在一定条件下，左、右手系材料界面上既可以支持正向传播的非线性TE表面波，也可以支持反向传播的非线性TE表面波；两左手系材料界面上表面波的传播性质因材料参量的变化差异较大，一定参量条件下，该界面上仅支持反向传播的非线性TE表面波。

Waves propagating with the electrons rotate their wave vectors downwards in the upper electrojet and upward in the lower electrojet.

这是由于波的群速度方向是向下的，而电子密度梯度起稳定化作用。对于电子密度的特征长度L_N=6km和│E_D│=0.8mV/m，波长λ=10m，高度h≥105km，有r0。

Left-handed materials have many strange properties,such as negative refractive index, negative group velocity ,perfect imaging,inverse Doppler effect and abnormal Cerenkov radiation.

本文介绍了左手材料的概念、原理和它具有的负群速度、负折射率、理想成像、逆Doppler频移、反常Cerenkov辐射等种种奇异的物理性质。

They have many strange properties such as negative group velocity , negative refractive index, perfect imaging, inverse Doppler effect and abnormal Cerenkov radiation.

它具有诸如负群速度、负折射率、理想成像、逆Doppler频移、反常Cerenkov辐射等种种奇异的物理性质。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。