共查询到20条相似文献，搜索用时 187 毫秒
1.
2.
通过对数据的分析处理从两个方面：重复性测量结果分析和平行性测量结果分析对激光粒度仪的性能进行了误差分析。重复性测量结果分析主要是对一台仪器的多个土样重复试验的测量数据进行分析处理,平行性测量结果分析主要是对两台仪器对同一土样进行试验的测量数据分析处理。两次分析的结果表明激光粒度仪的性能良好,在土工试验的颗粒分析中可以被推广使用。 相似文献
3.
4.
文章对开鲁气象站自动观测代替人工观测后气温要素进行了对比评估分析。分别对气温要素的观测值、日值、月值进行对比差值、差值平均值的对比分析。得出：开鲁气象站气温自动观测数据同人工卿．删精据-羁_有时问一贽性．可以同人工卿．测的信化历史数据连续使用． 相似文献
5.
针对旅行商(traveling salesman problem,TSP)是一个NP问题,本文使用改进的人工鱼群算法(improved artificial fish swarm algorithm,AFSA)进行线路的优化.首先阐述了TSP问题基本概念,其次针对基本的人工鱼群算法分别优化:(1)使用Laplace进行种群初始化,提高种群多样性;(2)使用正弦余弦算法取代觅食行为,保证算法在全局和局部范围内具有一定的平衡性;(3)利用人工蜂群算法对每一次迭代后的个体进行筛选,保证了算法的解的质量.仿真实验中本文算法在TSP路径规划方面具有一定的效果. 相似文献
6.
地面气象观测人工站与自动站记录差异浅析 总被引：1，自引：0，他引：1
自动与人工两种观测体制所获取的气象数据之间的差异,是仪器原理差异、观测时空的差异、采样方式的差异、人工观测人为误差造成的差异。自动观测的数据优于人工观测,更能反映大气中各要素的真实状况。 相似文献
7.
日前，陕西省政府副秘书长刘孝亲切会见了世界名云雾物理和人工影响天气专家、美国犹他大学教授Norihiko Fukuta。双方进行了友好的交谈，刘副秘书长代表省政府对Fukuta教授的来访表示欢迎，感谢他对陕西省气象事业所作的工作，并希望Fukuta教授能常来陕西，开展更多的合作与交流，促进气象事业的发展。Fukuta教授对陕西省的人工影响天气工作给了充分的肯定。 相似文献
8.
9.
经济的发展推动科技的进步,人工影响天气作业越来越多的被应用到气象灾害的防治中,通过合理的气候资源利用,满足地区需求情况。人工影响天气作业的增雨效果能够为有需求地区达到良好的抗旱作用。在贵州省部分地区容易出现干旱灾害,通过人工影响天气作业有效降低灾害损失。本文将就贵州的飞机人工增雨效果进行分析,总结人工增雨作业带来的效益,以及提出为了更好的开展人工影响天气作业技术的对策建议。 相似文献
10.
11.
Optical chromatography relies on the balance between the opposing optical and fluid drag forces acting on a particle. A typical configuration involves a loosely focused laser directly counter to the flow of particle-laden fluid passing through a microfluidic device. This equilibrium depends on the intrinsic properties of the particle, including size, shape, and refractive index. As such, uniquely fine separations are possible using this technique. Here, we demonstrate how matching the diameter of a microfluidic flow channel to that of the focusing laser in concert with a unique microfluidic platform can be used as a method to fractionate closely related particles in a mixed sample. This microfluidic network allows for a monodisperse sample of both polystyrene and poly(methyl methacrylate) spheres to be injected, hydrodynamically focused, and completely separated. To test the limit of separation, a mixed polystyrene sample containing two particles varying in diameter by less than 0.5 μm was run in the system. The analysis of the resulting separation sets the framework for continued work to perform ultra-fine separations. 相似文献
12.
以纯净硫酸锰溶液为原料,采用液相沉淀法,制备出前驱粉体氢氧化锰,再用液相氧化制得四氧化三锰的试验。并对比了焙烧法和一步法合成四氧化三锰的方法的优劣。并用XRD——X射线衍射仪、BET氮气吸附法、激光粒度测试仪(JL.1178)、原子吸收分光光度计(TAS系列)对产品进行分析测试,结果表明以前驱粉体氢氧化锰,采用液相氧化制得的四氧化三锰合符电子级四氧化三锰的标准。 相似文献
13.
This paper presents a mathematical model for laser-induced rapid electro-kinetic patterning (REP) to elucidate the mechanism for concentrating particles in a microchannel non-destructively and non-invasively. COMSOL®(v4.2a) multiphysics software was used to examine the effect of a variety of parameters on the focusing performance of the REP. A mathematical model of the REP was developed based on the AC electrothermal flow (ACET) equations, the dielectrophoresis (DEP) equation, the energy balance equation, the Navier-Stokes equation, and the concentration-distribution equation. The medium was assumed to be a diluted solute, and different electric potentials and laser illumination were applied to the desired place. Gold (Au) electrodes were used at the top and bottom of a microchannel. For model validation, the simulation results were compared with the experimental data. The results revealed the formation of a toroidal microvortex via the ACET effect, which was generated due to laser illumination and joule-heating in the area of interest. In addition, under some conditions, such as the frequency of AC, the DEP velocity, and the particle size, the ACET force enhances and compresses resulting in the concentration of particles. The conditions of the DEP velocity and the ACET velocity are presented in detail with a comparison of the experimental results. 相似文献
14.
The relation between particle size and the degree of polarization of the Tyndall beam created by suspension of non-uniform particulate substances was investigated for three materials (silica, granite, and calcite) ranging in size from one to fifty microns. The degree of polarization was found to be a function of the arithmetic mean diameter of the material. The optical property of birefringence was also found to be a determining factor although its effect was not studied quantitatively. It is shown that by combining the equation expressing the relation between particle size and strength of Tyndall beam with the mathematical relation between degree of polarization and particle size, an indirect method of obtaining a complete definition of particle size is given. Particle size values calculated from observed Tyndall readings and measurements of polarization were found to be within approximately ten per cent. of observed values. 相似文献
15.
高精度输出半导体激光器的温度控制系统设计 总被引：1，自引：0，他引：1
本文利用高信噪比的运算放大器、半导体制冷器,设计了一种激光器的温控系统,其能为半导体激光器提供高稳定度的恒温控制(ATC),从而提高了半导体激光器的使用寿命和输出波长的单一性。 相似文献
16.
Hasan Ebrahimi Shahmabadi Seyed Kazem Bagherpour Doun Seyed Ebrahim Alavi Mehri Mortazavi Zahra Saffari Maryam Farahnak Azim Akbarzadeh 《Indian journal of clinical biochemistry : IJCB》2014,29(3):357-361
Emulsion polymerization was used to synthesize poly butyl cyanoacrylate nanoparticles in presence of steric stabilizer dextran 70. Nanoparticles were characterized by particle size analysis, scanning electron microscopy and light microscopy. Polymerization factors affecting particle size and distribution such as dextran 70, polysorbate 80 (PS 80) and H+ concentration, polymerization time and temperature, and sonication were studied. Distinct concentrations of stabilizer were needed to produce proper nanoparticles. In this case, the appropriate value was 2 % of total volume. At pH 4 significant decrease in production efficiency demonstrated the substantial effect of H+ concentration on nanoparticles. Furthermore significant increases in particle size and distribution was observed at 50 °C compared to room temperature. 0.001 % (v/v) PS 80 represented notable influence on size and distribution. In addition, shaped nanoparticles were obtained by altering polymerization time from 5.5 h to 18 h. Finally, nanoparticle features were influenced by different factors. Appropriate manipulating of such factors can lead to obtaining desirable nanoparticles. 相似文献
17.
对比了醋酸乙烯（VAC）在传统聚合中和超声波辅助聚合中的单体转化率和乳液粒径分布的差别。在VAC聚合过程中外加超声波环境，单体转化率从92.5 %提高到98.8%，乳液粒子平均粒径从136.7nm减小到101.4nm。在超声波辅助VAC乳液聚合中，研究了引发剂浓度和反应温度对单体转化率及乳液粒径分布的影响。试验结果表明仅靠超声波产生的自由基不足以引发聚合反应，引发剂分解产生的自由基在引发聚合过程中起着重要的作用。简单介绍了超声波辅助乳液聚合的机理，超声波可以连续提供自由基，而这些自由基的作用是使死聚合物链变的有活性，导致单体具有较高的转化率。 相似文献
18.
Xinyu Lu Saurin Patel Meng Zhang Sang Woo Joo Shizhi Qian Amod Ogale Xiangchun Xuan 《Biomicrofluidics》2014,8(2)
Electrophoresis plays an important role in many applications, which, however, has so far been extensively studied in Newtonian fluids only. This work presents the first experimental investigation of particle electrophoresis in viscoelastic polyethylene oxide (PEO) solutions through a microchannel constriction under pure DC electric fields. An oscillatory particle motion is observed in the constriction region, which is distinctly different from the particle behavior in a polymer-free Newtonian fluid. This stream-wise particle oscillation continues until a sufficient number of particles form a chain to pass through the constriction completely. It is speculated that such an unexpected particle oscillating phenomenon is a consequence of the competition between electrokinetic force and viscoelastic force induced in the constriction. The electric field magnitude, particle size, and PEO concentration are all found to positively affect this viscoelasticity-related particle oscillation due to their respective influences on the two forces. 相似文献
19.
A size-selective cell sorting microfluidic device that utilizes optical force is developed. The device consists of a three-dimensional polydimethylsiloxane microstructure comprised of two crossed microchannels in a three-dimensional configuration. A line shaped focused laser beam is used for automatic size-selective cell sorting in a continuous flow environment. As yeast cells in an aqueous medium are fed continuously into a lower channel, the line shaped focused laser beam is applied (perpendicular to the direction of flow) at the junction of the two crossed channels. The scattering force of the laser beam was employed to push cells matching specific criteria upward from one channel to another. The force depends on the size of the cells, the laser power, and the fluid flow speed. The variation in size of yeast cells causes them to follow different routes at the intersection. For flow speeds below 30 μm∕s, all yeast cells larger than 3 μm were removed from the main stream. As a result, a high purity sample of small cells can be collected at the outlet of bottom channel. 相似文献
20.
本文采用有限元方法对金刚石/铜复合材料的传热性进行数值模拟,建立多颗粒二维随机分布复合材料测试模型,研究金刚石颗粒体积分数、颗粒半径、颗粒形貌、粒径比及界面因素对金刚石/铜复合材料传热性能的影响规律及机制。结果表明:金刚石/铜复合材料的热导率随着金刚石体积分数的增大而升高;热导率随着粒径的增大而呈现先升高后降低的规律;方形金刚石颗粒的复合材料热导率高于球形颗粒的复合材料;在金刚石体积分数一定时,适量配比细颗粒可提高材料热导率;对金刚石表面镀覆层新物质(W、Cr、Ti)来等效金刚石和铜二者物理结合时的界面热阻。 相似文献