自蔓燃工艺制备纳米TiO2降解制药废水的研究

目前已报道的制备纳米二氧化钛的方法有气相氧化法[1,2]、水热法[1,3]和溶胶-凝胶(sol-gel)法[1,4,5]等。这些方法均以有机钛盐或无机钛盐为原料,制备成本高,不利于在废水处理中作光催化剂推广使用。溶胶—凝胶自蔓燃法(简称SAS)也称低温燃烧合成法,由于工艺简单、反应条件易于     

Scale-adaptive simulation of flow past wavy cylinders at a subcritical Reynolds number

The Xu & Yan scale-adaptive simulation (XYSAS) model is employed to simulate the flows past wavy cylinders at Reynolds number 8 × 10 3.This approach yields results in good agreement with experimental measurements.The mean flow field and near wake vortex structure are replicated and compared with that of a corresponding circular cylinder.The effects of wavelength ratios λ/D m from 3 to 7,together with the amplitude ratios a /D m of 0.091 and 0.25,are fully investigated.Owing to the wavy configuration,a maximum reduction of Strouhal number and root-meansquare (r.m.s) fluctuating lift coefficients are up to 50% and 92%,respectively,which means the vortex induced vibration (VIV) could be effectively alleviated at certain larger values of λ/D m and a /D m.Also,the drag coefficients can be reduced by 30%.It is found that the flow field presents contrary patterns with the increase of λ/D m.The free shear layer becomes much more stable and rolls up into mature vortex only further downstream when λ/D m falls in the range of 5-7.The amplitude ratio a /D m greatly changes the separation line,and subsequently influences the wake structures.     

一种基于血氧饱和度与鼾声检测的呼吸暂停监测系统设计

长期打鼾严重的人往往都患有呼吸暂停综合征, 该症状对人的身体健康有着极大的危害. 针对用鼾声实现呼吸暂停检测技术准确度不够的问题, 设计了一种基于血氧饱和度与鼾声检测相结合的呼吸暂停监测系统, 利用微控制器结合外部的血氧检测电路以及鼾声检测电路实现血氧饱和度的实时监测与鼾声片段的识别, 当监测到用户睡眠时正在打鼾同时血氧饱和度在一定程度上下降, 系统便可以识别出该打鼾者的呼吸暂停症状. 而对于患有呼吸暂停症状的打鼾者, 后续可以对其进行止鼾, 从而一定程度上可以缓解呼吸暂停症状. 整个系统在准确实时的血氧饱和度监测以及鼾声识别基础上, 可以较为方便准确地识别出打鼾者的呼吸暂停症状, 为呼吸暂停综合征的实时监测提供了一种新的方法.     

均匀设计中有重复试验的统计分析

本文先简要介绍有重复试验的回归分析理论及公式 ,再对一个例子重新给以计算及提出问题 ;最后笔者对此类数据的处理及 SAS统计软件包提出讨论意见 ,其中特别对常规的用平均数去取代试验结果的方法及当变量数超过样本数时用流行的逐步回归选取变量法提出批评。     

我国各地区城乡居民人均收入的对应分析

利用SAS软件 ,对我国 1999年度的城乡居民人均收入的统计资料进行了对应分析 ,又对城乡、东西部地区居民的收入进行了均值差异检验 ,得到了许多有意义的结果。     

SAS6.11版岭回归分析程序设计及其实例分析

应用岭回归分析可以解决自变量之间存在复共线性时的回归问题。本文给出了在SAS6.1 1及以上版本中实现岭回归分析的程序 ,用具体实例说明进行岭回归的方法     

两类判别的ROC曲线与SAS语句

在综合指标是正态分布条件下 ,本文给出求两类总体分界点的 ROC曲线 ,从中可以人为地决定一个分界点。同时给出求 ROC曲线及不同分界点时的错判率     

二次回归正交设计在天然橡胶复合材料制备工艺中的应用

本文通过二次回归正交设计,对天然橡胶复合材料制备工艺中有机土浓度、分散剂浓度、胶乳浓度和土填充量四个因子进行研究。结果表明,当有机土浓度取6.4%,分散剂浓度取50.7%,胶乳浓度取22.9%,土填充量取7.0%时,可以使天然橡胶复合材料的硬度达到最佳值。     

Analysis of the Initial Slope of the Small‐Angle Scattering Correlation Function of a Particle

The small‐angle scattering correlation function of a particle γ(r) results from scattering experiments. This function possesses a well‐defined slope γ′(0) at the origin. This slope is defined by the particle volume V and the whole surface area S of the particle via γ′(0) = –S/(4V). In this paper it is demonstrated that this slope defines the mean chord length of the particle, . This theorem involves non‐convex particles, especially the case of particles with hollow parts. Consequently, for a large class of particle shapes the mean chord length is defined in terms of V and S. This extension of the Cauchy theorem is developed by closer analysis of the set covariance C(r), of the small‐angle scattering correlation function γ(r), and of the so‐called linear erosion P(r) near the origin r→0. The cases of a single hollow sphere, of two touching spheres, and of the single hollow cylinder are discussed.