Dechlorination of 2,4-dichlorophenol by nickel nanoparticles under the acidic conditions

Metal nanoparticles are effective for remediation of contamination with a range of compounds including chlorinated organics.However,the sorption process of the passivation oxide layers on the metal nanoparticle surfaces may result in incomplete degradation of contaminants.This phenomenon can be prevented by an acidic washing procedure or reaction in an acidic medium.In this paper,nickel nanoparticles manufactured via the carbonyl powder process were analyzed using scanning electron microscopy,transmission electron microscopy,X-ray diffraction and energy-dispersive X-ray spectroscopy.The sorption and degradation of 2,4-dichlorophenol (2,4-DCP) by nickel nanoparticles under acidic conditions was then investigated.Transmission electron microscopy and XRD results showed that the nickel nanoparticles range in size from 10 to 20 nm,and a thin passivation layer of NiO is present on the surface.This oxide layer can be removed by pretreatment washing with acidic solutions.It was indicated that dechlorination was the key reaction pathway for degradation of 2,4-DCP by nickel nanoparticles under acidic conditions.The main degradation products were 4-Chlorophenol,2-Chlorophenol,and Phenol,and among these,Phenol was dominant.The acidic medium promoted degradation by providing an appropriate pH,and H+ may be involved in the reaction.Dechlorination of 2,4-DCP by nickel nanoparticles under the acidic condition follows the second order kinetic model,and the rate constants at 298,306,316 K are 0.02,0.2 and 0.3 (g L h)-1,respectively.     

基于能值分析的湖州市可持续发展水平研究

采用能值分析理论探讨1993-2007年湖州市可持续发展水平指标EsI的变化情况,定量研究湖州市的可持续发展水平.研究表明,湖州市可持续发展水平指数从1993年的102下降到2006年的4.09;其中1993-1995年以及1998-2000年快速下降,1995一1998年缓慢上升,2000年之后该指标缓慢下降;指标缓...     

基于混沌加密和连词替换的文本水印算法

提出了一种基于连词替换的文本水印嵌入方法。首先,要让水印信息通过混沌系统得到加密信息,再把加密信息与密钥进行异或运算得到待嵌入信息,然后对再对载体文本进行分词等预处理,找到所有符合替换规则的连词,根据待嵌入信息和连词替换表确定文本中的嵌入位置,修改后生成含水印文本。其特点是水印嵌入灵活,隐蔽性好,对于各种水印攻击有较强...     

科技企业孵化器建设管理水平和创业孵化能力新要求探讨

分析了《科技企业孵化器认定和管理办法》的制定背景、重要意义、基本内容、主要特点,提出了提升科技企业孵化器建设管理水平和创业孵化能力的新要求。     

Detecting non-stationarity for auscultation signal of traditional Chinese medicine

The information about the nonstationarity of the aus-cultation signal is utilized in this paper to objectively and auto-matically identify healthy people and patients with qi-deficiency or yin-deficiency. In order to characterize the nonstationarity of the sound signal,the nonlinear cross-prediction method is used to extract features from the signal. A feature selection method based on conditional mutual information maximization criterion (CMIM) is implemented to find an optimal feature set. By means of the support vector machine (SVM) classifier,three common states (healthy,qi-deficiency and yin-deficiency) in traditional Chinese medicine are distinguished using the feature set,and a satisfactory classification accuracy of 80% is achieved in the experiment. In conclusion,the analysis based on the nonstationarity of the sound signal provides an alternative and outstanding approach to the objective auscultation of traditional Chinese medicine (TCM).     

基于EMD的概率数据top-k相似性连接

选取EMD(earth mover’s distance)作为度量概率数据相似性的标准.EMD具有抗噪性好,对概率分布间的微小偏移不敏感等优良特性,但却具有三次方的复杂度.针对此问题,提出EMD-kJoin算法,在相似性搜索方面,基于线性规划的对偶理论为概率数据构建索引,避免不必要的EMD求精计算;在处理流程方面,以复杂度较低的范围查询为主要操作,并逐步缩小搜索阈值.通过使用真实数据集对EMD-k Join进行测试,证明EMD-k Join极大提高了基于EMD的概率数据top-k相似性连接操作的执行效率.     

基于MapReduce的关系型数据仓库并行查询

针对MapReduce框架与传统关系型数据库兼容性不好的问题,提出了一种基于分块结构的分布式关系数据库ChunkDB.并对MapReduce架构进行了扩展设计,使ChunkDB与MapReduce有效结合,将MapReduce的扩展性、易操作性、高并行性与关系数据库的索引等查询优化优势相结合.实验证明基于MapReduce的ChunkDB数据库能够为数据仓库应用提供快速高效的并行查询.     

基于改进C-V模型的脑组织提取算法

通过对水平集算法C-V模型进行三方面改进,提出一种基于改进C-V模型的脑组织提取算法.首先,通过改进经典的距离函数,在保证准确度的同时,可以在很大程度上加快距离函数的收敛,提高分割速度.其次,改进了收敛结果的唯一性,使边缘停止在欲提取的目标类灰度上,用于去除脑脊液,使脑灰质、白质的提取更加准确.最后,提出了迭代收敛的动...     

探析“用工荒”

"用工荒"在近几年愈演愈烈,分析"用工荒"的成因,探索破解"用工荒"的途径,对于中国经济的发展有着积极的意义。     

急斜特厚煤层动力学失稳现场声发射监测

急斜特厚煤层开采扰动区(Mining Disturbed Zone,MDZ)煤岩应力与变形规律复杂,采动影响下局部煤岩层滑移造成应力集中,使煤岩体产生"强烈"的动力学失稳与破坏.以大洪沟煤矿B3+6急斜特厚煤层综放开采为工程背景,通过现场声发射(acoustic emission,AE)监测,分析采动条件下煤岩介质动力学失稳及破坏规律,为制定解危对策提供科学依据.