查询词典 particle

The influences of the shock thickness and Alfven waves on the particle acceleration by diffusive shock waves are numerically studied through solving one-dimensional diffusive equation including the second-order Fermi effect. It is shown that the spectral index of the energetic particles strongly depends on the shock thickness. For example, the spectral index increases from 2.1 to 3.7 in the low energy range of 3-10 MeV and from 2.5 to 5.0 in the high energy range of 20-60 MeV as the thickness increases. The spectral index decreases from 4.3 to 3.1 as the particle injection energy increases. The spectral index decreases from 4.0 to 1.8 at the quasi-steady stage with the enhancement of the compression ratio from 2 to 4. The results indicate that under the influence of Alfven waves, the energetic particle spectrum at lower energy becomes flat and the spectral index decreases from 2.5 to 0.6 in the low energy range of 3-10 MeV and from 11.6 to 5.0 in the high energy range of 20-60 MeV. At the same time, the rollover energy reaches 19.6 MeV. The spectral index decreases from 5.8 to 2.9 as the energy density of Alfven waves increase. All these results are basically consistent with the theoretical models, as well as the observations of typical energetic particle events.

通过数值求解包含二阶费米加速的一维扩散方程，探讨在准平行激波条件下激波厚度和级联阿尔芬波对粒子加速的影响，研究粒子分布函数的演化与激波厚度和阿尔芬波强度的内禀关系，计算结果表明：(1)考虑激波厚度时，谱指数明显依赖于激波厚度，随着厚度从0.32增大到2.56，低能端(3-10MeV)谱指数逐渐从2.1增加到3.7，高能端(20-60MeV)谱指数从2.4增大到5.0，能谱逐渐变软；当初始注入粒子动量增大1.3倍，质子能谱指数从4.3减小到3.1，且与零厚度激波加速的谱指数差值缩小；厚度不变时，随着压缩比从2增加到4，准稳态分布时低能端(3-10MeV)粒子能谱指数逐渐从4.0减小到1.8谱变硬；(2)在级联阿尔芬波的影响下，随着时间的增大，粒子在低能处(3-10MeV)的谱指数从2.5减小到0.6高能端(20-60MeV)谱指数从11.6减小到5.0，能谱变硬，拐点能量值从7.5MeV增大到为19.6MeV；随着波的能量密度增大，谱指数从5.8减小到2.9，这表明阿尔芬波强度越大，加速效率越高，通过与激波厚度解析结果和高能粒子事件的观测能谱比较发现两者是一致的，说明数值模拟结果是可靠的。

All of particles complies with Gaussian distribution, meanwhile calculates particle numbers According to mass percentage, and selects parameter of particle and wall. The gradation of Bailey method about the maximum nominal particle diameter 16 mm is simulated by PFC2D, such as CA0.2, CA0.4, CA0.5, CA0.6, CA0.8. Determine moveability of asphalt mixture through rolling distance of accumulation particle it's when asphalt mixture is stable at the gravitation. Computer simulation result is identical to testing result.

首次采用PFC2D程序的线性接触刚度模型，选取颗粒和墙体参数，按设计质量的百分比换算成颗粒数量，按照高斯分布规律排列颗粒构成，对贝雷法设计的公称最大粒径为16mm的级配CA0.2、CA0.4、CA0.5、CA0.6、CA0.8进行堆积模拟，在重力作用下形成自然堆积，测定混合料基本稳定时的滚动距离来判断混合料的分离程度，得到结果与离析势能指数的测定结果完全一致。

In order to seamlessly combine NSGA-Ⅱ and the greatly different MOPSO, the special concepts (particle and its velocity, Pbest and leader) for MOPSO were dealt with within the scope of NSGA-Ⅱ: 1 particle in MOPSO was considered to be equivalent to offspring individual in NSGA-Ⅱ; 2 the concept of velocity fell into disuse; 3 the concept of Pbest also came into disuse. Instead of that, for each dimension of a particle, the nearest one among its nondominated individuals in parent population was used; 4 the leader of a particle was the individual with largest sparse degree among parent population or selected from parent population by binary tournament selection method, which of them taking effect lies on the predefined probability. In addition, a new concept, i.

为使这两种差异较大的算法实现无缝融合，在NSGA-Ⅱ算法范围内对MOPSO中特有的概念粒子及其速度、Pbest、引导者进行处理：1粒子对应于NSCA-Ⅱ中子代群体的个体；2不再使用粒子速度概念；3不再使用粒子Pbest概念，代之以从父代群体中为每个粒子的每一维寻找一个最近的该粒子非支配个体；4每一个粒子的引导者可以是父代群体中稀疏程度最大的个体或者是按照二进制随机竞赛选择方法从父代群体中选择的一个个体，具体哪一种方式发挥作用依赖于预先设定的概率。

Under the condition of pure thermal load, enlargement of particle size and lengthdiameter ratio and particle cluster will increase the serious plastic thermal residual strain concentration in the matrix near the pointed particle corner and the serious compressive thermal residual stress concentration in the pointed particle corner.

发现在纯热载荷作用下，颗粒尺寸加大、长径比加大及颗粒的团聚会使颗粒尖角附近基体的塑性热残余应变集中和颗粒尖角上严重的残余压应力集中加剧。

In this paper, the sorting of wear, the mechanics of wear particle formed and the characteristics of wear particles are introduced, and morphology characteristics parameter of wear particle are determined, which is particle brim digital feature. Based on image characters, after pre-process, section and extracting of contour parameter of wear particle using image process technique, four shape character parameters are extracted by fourier series expansion. After analyzing fundamental principle and shortcomings of neural network, current BP algorithm is improved in output optimization, network linearization implication optimization and adding momentum, and then astringe speed of BP algorithm.

本文介绍了磨损的分类以及磨粒的生成机理、磨粒的形态特征，应用摩擦学系统分析的观点，确定磨粒边缘数字特征为磨粒的识别特征参数；根据磨粒图像的特征，利用计算机图像处理技术对磨粒图像进行预处理、分割、轮廓参数的提取，采用傅立叶级数展开式提取磨粒四个形状特征参数：圆形度、散射度、凹度、细长度；针对 BP(Back-Propagation)神经网络收敛速度慢的特点，对现行的 BP 算法进行改进，并通过实验验证改进后的网络收敛速度快；研究设计了磨粒图像采集系统；利用 BP 算法建立磨损磨粒自动识别算法模型 AWPRM(Auto Wear Particle Recognition Model)。

The experimental results showed that SiC ultrafine powder was synthesized at 1500℃for 120 minutes by used rare earth lanthanum as additive. Its primary particle size was about 100nm and aggregated particle size was about 360nm and the particle shape was regulation, non-aggregation and well dispersibility. While the rare earth ceria used as the additive, SiC ultrafine powder was synthesized at 1500℃for 150 minutes but the particle shape was irregulation and seriously agglomerated and had numerous crystal whiskers.

实验结果表明：以稀土镧为添加剂时，在1500℃×120min合成工艺下，可以合成出一次粒径为100nm左右，二次粒径为360nm的SiC细粉，且SiC粉体颗粒形状规则，无团聚，分散性好；以稀土铈为添加剂时，在1500℃×150min合成工艺下，也可以得到单相的SiC，但SiC粉体颗粒形状不规则，有大量晶须存在，且团聚严重。

Moreover, nano-scale SiO〓 particle is as seed, styrene-acrylate-acrylic acid emulsion polymerization and soapless acrylic emulsion are studied from varying the level of SiO〓 particle and reaction temperature, particle size of these emulsions are determined and SiO〓 content of participating polymerization is also determined. Kinetic study is carried out in the presence of nano-scale SiO〓 particle.

此外用原位聚合法制备了纳米SiO〓/苯乙烯-丙烯酸酯复合乳液和无皂丙烯酸乳液，研究了不同SiO〓含量、反应温度等对聚合反应稳定性的影响，测定了所得乳胶粒的粒径，分析了在乳液中SiO〓含量，并进行了在SiO〓存在下乳液聚合反应的动力学研究。

Finally, he air velocity, the velocity of the wood particle, the relative velocity between the air and the wood particle, the wood particle's residence time and the variations of the particle's velocity along radial and circle are measured. The ISD of particles is analyzed on dynamics.

最后，测量了气流速度、刨花速度、刨花与气流间的相对速度、刨花在半环内的停留时间及刨花在半环内沿径向和周向的速度分布，并地基础上进行了刨花对撞流干燥的动力学分析。

Finally, the air velocity, the velocity of the wood particle, the relative velocity between the air and the wood particle, the wood particle's residence time and the variations of the particle's velocity along radial and circle are measured.

最后，测量了气流速度、刨花速度、刨花与气流间的相对速度、刨花在半环内的停留时间及刨花在半环内沿径向和周向的速度分布，并在实验基础上进行了刨花对撞流干燥的动力学分析。

Finally,the air velocity,the velocity of the wood particle, the relative velocity between the air and the wood particle,the wood particle's residence time and the variations of the particle's velocity along radial and circle are measured. The ISD of particles is analyzed on dynamics.

最后，测量了气流速度、刨花速度、刨花与气流间的相对速度、刨花在半环内的停留时间及刨花在半环内沿径向和周向的速度分布，并地基础上进行了刨花对撞流干燥的动力学分析。

Article 144 The Government of the Hong Kong Special Administrative Region shall maintain the policy previously practised in Hong Kong in respect of subventions for non-governmental organizations in fields such as education, medicine and health, culture, art, recreation, sports, social welfare and social

第一百四十四条香港特别行政区政府保持原在香港实行的对教育、医疗卫生、文化、艺术、康乐、体育、社会福利、社会工作等方面的民间团体机构的资助政策。原在香港各资助机构任职的人员均可根据原有制度继续受聘。

Small wonder, then, that the Chinese spend more in the shop than any other group of foreign visitors do .

这样的小惊喜，使中国顾客比任何国家的人消费得更多。