Molecular dynamics simulation on flow behavior of nanofluids between flat plates under shear flow condition

Molecular dynamic model of nanofluid between flat plates under shear flow conditions was built. The nanofluid model consisted of 12 spherical copper nanoparticles with each particle diameter of 4 nm and argon atoms as base liquid. The Lennard–Jones (LJ) potential function was adopted to deal with the interactions between atoms. Thus, the motion states of nanoparticles during the process of flowing were obtained and the flow behaviors of nanofluid between flat plates at different moments could be analyzed. The simulation results showed that an absorption layer of argon atoms existed surrounding each nanoparticle and would accompany with the particle to move. The absorption layer contributed little to the flow of nanoparticles but much to the heat transferring in nanofluids. Another phenomenon observed during shear flowing process was that the nanoparticles would vibrate and rotate besides main flowing with liquid argon and these micro-motions could strengthen partial flowing in nanofluids.     

一种基于码本聚类的低复杂度用户选择算法

现有块对角化(BD)预编码系统用户选择算法较少考虑利用已选用户与剩余用户之间的关系来排除不可选用户.针对这点不足,给出了一种采用码本聚类的低复杂度用户选择算法( CodeGreedy算法).该算法采用弦距离刻画用户信道的相关性,以此为依据将用户划分到不同码本空间中,聚集在同一码本空间的用户信道具有较强的相关性,形成互斥...     

合成氨工艺参数优化技术开发及应用

以氨净值为响应值,影响响应值的17个过程参数为变量,经逐步回归选入触媒温度左3,触媒温度左4,循环CH_4%,H/N,NH_3%(进口)5个过程参数建立预测方程,并根据该方程对响应值的拟合结果和误差分布对样本进行分类。在此基础上,采取图形显示技术和统计分析的方法对分类样本集的过程参数进行比对分析,由此获取优类信息制订优化的工艺参数方案,经仿真验证后用于指导合成氨装置的生产试验。试验结果与试验前的对照期比较,氨净值均值由13.86提高到14.54,吨氨气耗减少15.9887m~3,吨氨电耗减少15.8kWh,节能效益十分明显     

网络时代知识产权犯罪问题研究及其对策

侵犯知识产权是互联网上一股来势凶猛的暗流!使传统的刑事法律受到挑战,迫切需要相关各界作出及时回应,从意识、法律和技术上加以遏制,以保护知识产权人的权利,进而维护全社会的科学技术和文学艺术的进步.     

动画动态定位在网页上的方法

网页上经常会显示一些动画,如重要信息或广告等。本文用JavaScript实现了使动画固定在网页画面的相对位置上,不会被移出画面。     

Polycrystalline diamond MESFETs by Au-mask technology for RF applications

Metal-semiconductor field effect transistors (MESFETs) were fabricated on H-terminated polycrystalline diamond.The DC characteristics of the p-channel MESFET showed a maximum drain current density of 204 mA/mm at a gate-source voltage of 6 V,and a maximum transconductance of 20 mS/mm at a gate-source voltage of 1.5 V.The small signal S-parameters of MESFET with 2 100 m gate width and 2 m gate length were measured.An extrinsic cut-off frequency (fT) of 1.7 GHz and the maximum oscillation frequency (fmax) of 2.5 GHz were obtained,which was the first report on diamond MESFETs with RF characteristics in China.     

The oxidation state of sulfur detected in Na2O-CaO-SiO2 float glass by X-ray absorption near edge structure spectra

The oxidation state of sulfur is detected in Na2O-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure (XANES) spectra at the sulfur K edge. The measured spectra show the only presence of S6+ in the Na2O-CaO-SiO2 float glass and the oxidation state of sulfur do not change with the increase of glass depth. It is also found that, after the melt has gone through the molten tin bath, the S6+ is the dominant species, but S2- is also present on both surfaces. It is not certain whether cation bonds to S2- or not, because there are many cations dissolved in the melted tin which makes the spectrum complicated.     

C*-代数中Moore-Penrose逆及Bott-Duffin逆的扰动分析

设A为C*-代数,a,-a=a δa∈A并且a 存在,‖a ‖‖δa‖<1。定义-a是a的稳定扰动,当且仅当-aA∩(1-aa )A={0}。此时-a 存在,并且‖-a ‖的上界被给出。对于B-D广义逆a p,在给出一般表达式的前提下,对于一类具有“p-零”性质的B-D广义逆,得到了‖-a p‖的一个上界。     

SiO2(am)在FoCa粘土和MX-80粘土中扩散实验的模拟

不定形二氧化硅[Amorphous Silica，简称SiO2（am）]是高放废物玻璃固化体在处置后，发生降解的主要产物。对SiO2（am）在FbCa粘土和MX-80粘土柱中的扩散迁移进行了实验研究，结果显示：在粘土柱中有大量的SiO2（am）沉淀产生；土柱中总Si增加量与时间的关系基本为线性正相关关系。采用CRUNCH程序对上述扩散迁移实验进行了模拟，模拟内容包括：溶液和岩相中Si浓度变化、总的筋增加量与时间的关系以及实验期间孔隙率的变化；同时分析了有效扩散系数对结果的影响。结果说明，使用CRUNCH程序进行反应迁移模拟是可行的；但是实验中pH值测量时机不适当；另外由于土样本身Si含量较高，易对土柱总Si的分析结果产生影响，这些因素需进一步实验时改进。     

65Mn热轧窄带钢的试轧

介绍了天津钢铁有限公司带钢厂开发带钢新品种,用65Mn弹簧钢试轧优质碳素结构钢钢带的工艺情况。总结了试轧过程存在的问题,提出了改进措施。