Experimental and MD simulation of 3-dodecyloxypropanamine and 3-tetradecyloxypropylamine adsorbed onto quartz (1 0 1) surface

In this paper, two surfactants, 3-dodecyloxypropanamine (DOPA) and 3-tetradecyloxypropylamine (TOPA), were synthesized and used as collectors in the quartz micro-flotation in the laboratory. Micro-flotation tests, FT-IR, XPS measurements, and ab initio Molecular Dynamics (MD) simulations were conducted to research DOPA, TOPA, and dodecylamine (DDA)'s adsorption mechanisms onto quartz (1 0 1) surfaces. The results of micro-flotation show that the adsorption of DOPA and TOPA onto quartz surface is more robust than that of DDA. The zeta-potential result shows that the DOPA/TOPA was adsorbed on quartz through electrostatic attraction. Then, MD simulation adsorption models were built to compare the computational properties of the three surfactants, such as the radial distribution function, and the interaction energies between the collectors and the quartz cleavage surface. The interaction energies of surfactants (RNH₃⁺ or RNH₂) on the quartz surface explained why the pH range of DOPA/TOPA is wider than that of DDA. XPS analyses and MD simulations confirmed that DOPA bonded with the (1 0 1) surface of quartz through three types of hydrogen bonds between the NH₂ of DOPA and the O atom of quartz. The hydrogen bonds of type A and type C were the most likely type and more potent than those of type B.     

国内外产品缺陷认定标准综述

本文对国内外产品缺陷认定标准进行论述,结合典型案例进行应用评析,通过梳理产品缺陷认定标准,可为我国产品缺陷认定标准制定和认定方法选择提供借鉴。     

Extended Fitts' law for 3D pointing tasks using 3D target arrangements

This study explored an extended 3D Fitts' model, which was more appropriate than the original Fitts' model for pointing tasks in 3D environment. The inclination angle and azimuth angle for spherical coordinate system were added to Fitts' original model formulation. Experiments were conducted by manipulating the distance to the target, the size of target, and the 3D target arrangement, which were described using the two angles of inclination (θ1) and azimuth (θ2). Given the starting point as the center of the coordinates, θ1 was the angle between the positive y-axis and the target location, while θ2 was the angle between the positive x-axis and the projected target location on the x–z plane. All four variables were found to be significant for the movement time (MT) (p < 0.0001). After incorporating the two variables, θ1 and θ2, into the original Fitts' model, the extended Fitts' model with 3D target arrangements for spherical coordinate system showed better agreement with the empirical data than previous models in terms of the correlation coefficient and the standard error of the residuals for the measured and predicted MTs.Relevance to industryThis study presents an extended Fitts' model with a higher degree of predictability than previous studies for pointing task in three-dimensional space. In many situations, people implement pointing tasks in a three-dimensional environment, so it is important for designers to predict human performance accurately. Instead of using Euclidean coordinate system, spherical coordinate system can be also used for 3D pointing tasks. The extended model with spherical coordinate system can be used during the design and evaluation stage of the development process to help designers and developers.     

ON STOCHASTIC CONVERGENCE THEOREMS FOR THE FUZZY C-MEANS CLUSTERING PROCEDURE∗

The fuzzy c-means clustering algorithm has been well studied for equal weight distributions on a finite set. Suppose that this situation is generalized to an arbitrary probability distribution on a finite dimensional Euclidean space, assuming that the second moment of the distribution is finite. Now choose ever larger finite random samples from this distribution and compute the standard optimal membership functions for a fuzzy partition into c clusters. Then the convergence of the cluster center points is established in the Hausdorff sense with probability one, provided that there is a unique optimal center point set. These optimal center points are the fixed point of a simple operator, and there is a corresponding iterative algorithm that generalizes the usual procedure.     

一种基于余弦定理的装备模拟相似度评估方法

为了构建完备的复杂电磁环境,经常使用模拟装备来扮演目标装备以满足要求。论文借鉴基于余弦定理的评估方法,对二者的关键参数进行定量分析与计算评判,量化评估了模拟装备的模拟相似度。结果表明,该种方法可有效解决二者的技术性能参数存在较大差异,导致其作战效能难以一致的现实难题。因此,这种方法可在一定程度上量化解决装备模拟逼真度评估的问题。     

消力塘透水底板脉动壁压幅值相似律研究

以底流消能情况下消力塘透水底板下表面脉动壁压为研究对象,设计了系列比尺(1∶1,1∶2,1∶4)模型试验,分析了透水底板脉动壁压强度、偏态系数、峰度系数以及概率密度函数沿程分布特征,并研究了系列比尺模型试验中脉动壁压幅值特性的相似律问题。结果表明,底流消能情况下消力塘透水底板脉动壁压幅值符合重力相似律。     

稳步推进长江流域综合管理的思考

在分析国外流域管理发展历程与现状的基础上,介绍了流域综合管理的概念、内涵、目标和任务。针对长江流域涉水事务管理现状和存在问题,从健全管理法规、创新管理体制、建立管理机制、完善管理制度、加强执法监督、提升管理能力等六个方面提出了推进长江流域综合管理的对策和措施。     

新环境保护法对强化水资源管理的作用与启示

全国人大常委会审议通过的新环境保护法在很多方面有重大创新和突破,建立了对经济技术政策的环境影响评价制度,强化了有关部门监测信息公开义务,建立了环境资源承载能力监测预警机制;赋予了有关部门查封、扣押的权力,建立了跨区域联合防治机制、"黑名单"制度等,完善了公益诉讼制度;设置了更加严厉的法律责任,创设了按日连续处罚和连带责任,增加规定地方政府及有关部门主要负责人"引咎辞职"的政治责任。这些规定对于水资源管理具有重要作用和启示,在水资源管理工作中应当积极运用该法有关规定,借鉴相关制度,完善相应的法规和政策措施,推进最严格水资源管理制度的有效实施。     

刘家峡水电站坝基承压水水位突降原因分析

介绍了刘家峡坝基承压水力突降情况,分析了承压水变化规律,揭示了承压水位突降是由于裂隙突然张开或裂隙的某一部位突然与相邻的上部裂隙潜水渗流或排水通道相连通造成的,阐明承压水与裂隙潜水的连通一般对大坝的安全不会构成威胁的观点。     

非对称模糊算法在微量紫外光度计中的应用

较传统的紫外可见分光光度计,微量紫外可见分光光度计具有体积小、分析速度快、需要样品体积小、便于测试高浓度溶液等优点.根据朗伯-比尔光吸收定律,得出吸光度相对误差和透射比误差之间的关系,可以针对不同浓度的待测溶液选择不同的测试光程来求得待测溶液的吸光度,有效提高了光度计的测量范围和精度.对同一待测溶液在不同测试光程下测试的结果中,应用非对称模糊算法选择出最合适的测试结果作为最终的测试结果.