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赵剑琦 《中国科学院研究生院学报》2010,27(3):323-330
研究了非吸收椭球形粒子尺度分布的反演问题.对于连续消光谱,得到了尺度分布与消光系数之间一个新的变换关系.对于离散消光谱,给出了基于Gamma分布展开的粒子尺度分布函数的级数表示,其中展开系数可通过求解相应的约束线性方程组来确定.在某种给定的反演精度下,实施积分所需的最短应测量波长与最小可反演粒径成正比.数值试验表明,本文所发展的解析技术是有效的,可容忍消光谱约5%的随机误差. 相似文献
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基于惠更斯-菲涅耳光学积分公式,结合光学传递矩阵,以矩形光阑为例,分析了透镜摆放位置对夫琅和费衍射光强分布的影响。所得结论与信息光学相关结果一致,但计算过程省去了复杂的积分变换,适宜在普通物理和光学教学中推广。 相似文献
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本文主要介绍了HTML5及基于HTML5的Canvas技术,利用该技术设计并实现了3D粒子图形动画,并介绍了3D动画的实现原理及步骤,展示了动画运行效果。 相似文献
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3D Studio MAX中共有6种粒子系统,基本粒子系统为Spray(喷射)和Snow(雪),高级粒子系统包括Vlizzard(摹风雪)、PArray(粒子列阵)、Pcloud(粒子云)和Super Spray(超级喷射).动力系统和粒子系统的结合可以将3D Studio MAX发挥到极至. 相似文献
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在磁性Fe3O4纳米粒子存在下,利用烯烃聚合后过渡金属催化剂α-二亚胺钯在温和条件下催化环戊烯原位聚合,通过聚环戊烯(PCP)在磁性纳米粒子表面原位异相成核结晶,成功获得一系列PCP包覆磁性Fe3O4纳米粒子。分别通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、热重分析(TGA)、差示扫描量热分析(DSC)、扫描电镜(SEM)和透射电镜(TEM)技术对产物结构进行了表征,结果表明PCP已成功包覆于磁性Fe3O4纳米粒子表面,所得复合型磁性纳米粒子仍具有较好的磁性能。 相似文献
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网络并发式流量特征具有信号时间可预测性,通过对网络流量的解卷积测度特征提取,提高对网络流量的预测性能。传统法方法采用粒子群优化算法实现对网络流量的特征测度盲解卷积分析,对原始信号的统计信息提取效果不好。提出一种基于粒子群退化重采样的网络流量解卷积测度提取算法,构建并发式网络流量序列采集模型,设计粒子退化重采样技术,将每个粒子的当前适应度值与其自身的个体最优值进行比较,如果优于个体最优值,得到粒子当前最优位置。仿真实验表明,采用该算法,收敛速度很快,在粒子群进化50代以内就可以实现成功收敛,对流量序列的测度特征提取结果准确,预测精度较高,展示了算法的优越性能。 相似文献
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In this work, we demonstrate the use of stereolithographic 3D printing to fabricate millifluidic devices, which are used to engineer particles with multiple compartments. As the 3D design is directly transferred to the actual prototype, this method accommodates 3D millimeter-scaled features that are difficult to achieve by either lithographic-based microfabrication or traditional macrofabrication techniques. We exploit this approach to produce millifluidic networks to deliver multiple fluidic components. By taking advantage of the laminar flow, the fluidic components can form liquid jets with distinct patterns, and each pattern has clear boundaries between the liquid phases. Afterwards, droplets with controlled size are fabricated by spraying the liquid jet in an electric field, and subsequently converted to particles after a solidification step. As a demonstration, we fabricate calcium alginate particles with structures of (1) slice-by-slice multiple lamellae, (2) concentric core-shells, and (3) petals surrounding the particle centers. Furthermore, distinct hybrid particles combining two or more of the above structures are also obtained. These compartmentalized particles impart spatially dependent functionalities and properties. To show their applicability, various ingredients, including fruit juices, drugs, and magnetic nanoparticles are encapsulated in the different compartments as proof-of-concepts for applications, including food, drug delivery, and bioassays. Our 3D printed electro-millifluidic approach represents a convenient and robust method to extend the range of structures of functional particles. 相似文献
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全息投影是一种利用干涉和衍射原理记录并再现物体真实的三维图像,观看者可以无需像现在的影院需要通过佩戴3D眼镜才能观看影片,从而实现真正的3D投影。然而全息投影的技术是一个展示平台,而真正观看的还是影片本身的内容,现在的技术对于全息三维场景成本还非常之高,需要大量的全息投影仪进行配合,但虚拟角色的技术结合全息投影已经相对成熟,并且运用面非常广。本文就全息投影技术中虚拟角色的制作与设计要点进行相关的分析以及论述。 相似文献
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We demonstrate an evaporation-based microfluidic strategy to produce oil-free cell containing hydrogel particles. Perfluoro-n-pentane, which is used as the continuous oil phase to generate cell-containing hydrogel (Extracel) particles, is removed at an elevated temperature. Human colon cancer cells (HCT116) encapsulated in the hydrogel particles show higher viability than cells encapsulated in particles that are produced via a non-evaporative oil phase. In addition, single HCT116 cells can be cultured for a week in such particles and respond to inflammatory stimuli, highlighting the potential applications of the developed strategy for 3D cell culture, drug testing, and cell-based drug delivery. 相似文献
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第一类曲面积分有重要的数学意义和物理背景,文章利用变量替换和函数的对称性对第一类曲面积分进行研究,给出了第一类曲面积分的逐项积分法等多种解法的应用。 相似文献
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本文给出了波色-爱因斯坦统计和费米-狄拉克统计中常用的积分以及一类形如的积分求解方法,对这些积分采用了新的方法进行了详细推导并给出一般性结论。 相似文献
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石家庄市秋季可吸入颗粒物垂直分布特征的研究 总被引：3，自引：0，他引：3
本文研究了石家庄市秋季可吸入颗粒物质量浓度垂直分布和粒度分布特征。结果表明，环境空气中可吸入颗粒物的众径为0.2μm～1.0μm，比表面积为3536.2～4396.06 m2/kg，PM2.5/PM10高达71.28％～81.14％； 细小颗粒物累积百分含量随高度增加而增加，PM2.5和PM10累积分布随高度增加呈现出对数增加的规律；采样高度1.5m时中位径（D50）>1μm，大于1.5m时 D50均<1μm。不同高度降尘的比表面积为336.55～790.06m2/kg，PM2.5/PM10为19.46～22.47％，D50为9.66～13.78μm，D98在34.93～53.48μm之间。 相似文献
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William Squire 《Journal of The Franklin Institute》1975,299(5):315-322
A modified Romberg procedure for evaluating complex integrals is applied to the computation of the Schwarz-Christoffel transformation. An iterative procedure proposed by Wassmuth is used to determine the constants of the transformation for flow past a polygonal boundary. The flow in a rectangular cavity and past a rectangular bump are computed. 相似文献
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In this paper, 3D particle focusing in a straight channel with asymmetrical expansion–contraction cavity arrays (ECCA channel) is achieved by exploiting the dean-flow-coupled elasto-inertial effects. First, the mechanism of particle focusing in both Newtonian and non-Newtonian fluids was introduced. Then particle focusing was demonstrated experimentally in this channel with Newtonian and non-Newtonian fluids using three different sized particles (3.2 μm, 4.8 μm, and 13 μm), respectively. Also, the effects of dean flow (or secondary flow) induced by expansion–contraction cavity arrays were highlighted by comparing the particle distributions in a single straight rectangular channel with that in the ECCA channel. Finally, the influences of flow rates and distances from the inlet on focusing performance in the ECCA channel were studied. The results show that in the ECCA channel particles are focused on the cavity side in Newtonian fluid due to the synthesis effects of inertial and dean-drag force, whereas the particles are focused on the opposite cavity side in non-Newtonian fluid due to the addition of viscoelastic force. Compared with the focusing performance in Newtonian fluid, the particles are more easily and better focused in non-Newtonian fluid. Besides, the Dean flow in visco-elastic fluid in the ECCA channel improves the particle focusing performance compared with that in a straight channel. A further advantage is three-dimensional (3D) particle focusing that in non-Newtonian fluid is realized according to the lateral side view of the channel while only two-dimensional (2D) particle focusing can be achieved in Newtonian fluid. Conclusively, this novel Dean-flow-coupled elasto-inertial microfluidic device could offer a continuous, sheathless, and high throughput (>10 000 s−1) 3D focusing performance, which may be valuable in various applications from high speed flow cytometry to cell counting, sorting, and analysis. 相似文献
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K.S. Bajaj 《Journal of The Franklin Institute》1975,300(3):193-196
A method for simulation by resistive networks is given for numbers like nm and n?m for 0 < m < 1. The method is based on Cauchy-type integral representations for irrational functions. An algorithm to get networks from Cauchy-type integrals is used in the paper. A similar method is used for simulation of transcendental numbers. Tapered resistive networks are obtained, which are easier to build by using integrated circuit technology. 相似文献