数据挖掘中聚类算法的研究简

随着信息技术的不断发展,数据挖掘在我们的工作和生活中的应用也越来越广泛,目前聚类算法在数据挖掘中则是一个热点研究领域。本文深入研究了现阶段比较成熟的几种聚类算法,总结了这些算法的优缺点以及适用范围,提出用来评价聚类算法性能优劣的指标,也是今后聚类算法研究的出发点。     

Measurement of minimum angle of resolution (MAR) in the stereoscopic display using the optotype of stereoscopic stimuli

In stereoscopic images, the crossing point of the viewing directions of the two eyes determines the perceived depth. Assuming that accommodation is affected by the positions of the crossing point, the effect of crossing point on minimum angle of resolution (MAR) was investigated. For 40 participants, MAR was measured by two‐alternative forced choice where Snellen optotype E of up and down directions were used as two kinds of stimuli. As the crossing point of the viewing direction of the left and right eyes moves farther from the sample display, the ability to identify the direction of letter E decreases at the optotype of the same line thickness. The change of MAR shows linear trends with respect to the optical power change that are the reciprocal of the distance from the participant to the crossing points located out of screen and on screen.     

Moisture adsorption characteristics of a thin bed of polycrystalline potash pellets: Part I. Experimental study

This study is an experimental investigation of heat and moisture transfer within a packed bed of polycrystalline, porous potash pellets. Experiments were first performed to determine the moisture uptake characteristics on individual pellets subject to a step-change in relative humidity. Then a bed of pellets was subjected to flows of humid air on the upper boundary and a cold impermeable surface on the lower boundary resulting in a temperature gradient across the bed. Temperature and moisture content were measured within the bed. It was found that moisture uptake is less for potash pellets and they are less likely to cake than granular and standard potash when subjected to the same ambient air conditions. This is due to the porous nature of the pellet and its nearly uniform size and spherical shape.     

二硝基芘异构体在模拟大气条件下的光化学反应

本文研究了二硝基芘异构体在模拟大气条件下的光化学反应，结果表明反应速率呈二级动力学关系，除光源变化的影响外，二硝基芘异构体在不同气氛中，反应速率不同，存在着氧的猝灭和氧化作用，而不同的异构体之间，相应的反应速度也不同。光解产物中存在硝基羟基类化合物、醌类和二聚体。毒理实验表明，光解产物致突变性下降。     

防止氟化铝母液脱硅工艺中铝、氟消耗方法研究

在氟化铝母液中添加氯化铝等可溶性铝盐,可有效地阻止钠,氟,铝间冰晶石固体物质的形成,从而达到防止氟化铝脱硅工艺中铝,氟的损耗,确保氟硅酸钠的产品质量,同时提高母液利用的经济效益。     

N-十六烷基乙二胺二乙酸钠的合成及性能研究

采用大量无水乙二胺与1－Br－十六烷反应合成N－十六烷基乙二胺，然后与过量氯乙酸作用制备N－十六烷基乙二胺二乙酸，用NaOH中和，即得N－十六烷基乙二胺二乙酸钠。该产物在硬水中的差示稳定性为333，优于LAS。在相同测试条件下，产物的去污力高于LAS，发泡力明显低于LAS。     

局部表面改性紫铜方柱阵列池沸腾传热特性和机理

以局部表面改性的紫铜直方柱和梯度方柱阵列为研究对象，实验研究了表面润湿性、表面形貌和表面活性剂对池沸腾换热性能和气泡生长特性的影响。实验工质为去离子水，浓度分别为100、200、400、800 mg·L^-1的异丙醇溶液和正庚醇溶液。实验结果表明：方柱阵列表面镀银之后润湿性变差，表面产生的气泡数量减少。向去离子水中添加异丙醇或正庚醇后，在热通量为66.1～202 kW·m^-2时，气泡脱离直径变小、数目减少，而当热通量增至413 kW·m^-2时，活性剂能够有效阻碍气泡合并，故池沸腾传热系数随着浓度增加先减小后增大。上下层宽分别0.5 mm和1 mm、间距为2 mm的梯度方柱阵列结构有助于气泡的合并，但由于促进了固体表面气膜的形成，从而降低了沸腾换热性能。     

Preparation and properties of electrospun poly(vinyl alcohol)/silver fiber web as wound dressings

A novel wound dressing material was prepared by electrospinning poly(vinyl alcohol) (PVA)/AgNO₃ aqueous solution into nonwoven webs and then treating the webs by heat or UV radiation. Through SEM, TEM, and XPS analyses, it was observed that the silver (Ag) nanoparticles were generated and existed in the near surface of the electrospun nanofibers. It was found that heat treatment as well as UV radiation reduced the Ag⁺⁺⁺ ions in the electrospun PVA/AgNO₃ fiber web into the Ag nanoparticles. Also the heat treatment improved the crystallinity of the electrospun PVA fiber web and so it made the web unsolved in moisture environment. Therefore, it was concluded that the only heat treated electrospun PVA/AgNO₃ fiber web was a good material as wound dressings because it had structural stability in moisture environment as well as excellent antimicrobial ability and, quick and continuous release of the effectiveness. POLYM. ENG. SCI., 47:43–49, 2007. © 2006 Society of Plastics Engineers     

海水反渗透淡化系统的能耗

通过对海水反渗透淡化系统（SWRO）吨水成本的分析，提出降低SWRO能耗的解决措施，采用能量透平装置（TURBO）或压力转换器（PE）回收浓水的能量传递于进水，不仅可以降低吨水电耗，也可减小一次性投资。值得关注的是，压力转换器，回收效率可达94％，在海水淡化系统中对于降低能耗有更重要的意义。     

非炭黑橡胶补强填料的应用研究进展

介绍非炭黑橡胶补强填料白炭黑、粘土、碳酸钙和短纤维的应用研究进展。白炭黑以其优良的补强性能成为最主要的白色、透明补强填充剂。白炭黑与硅烷偶联剂并用于轮胎胎面胶中，在降低轮胎滚动阻力的同时可改善轮胎的耐磨性和抗湿滑性。粘土／橡胶纳米复合材料具有良好的加工性能、优异的物理性能及阻隔性能等，广泛用于轮胎内胎、气密层、胶带、胶鞋等制品。碳酸钙尤其是超细活性碳酸钙已成为性能较好、白度高的橡胶补强填充剂之一，随着橡胶制品向品种齐全、用途广泛和色彩丰富方向发展，其应用将更加广泛。短纤维补强橡胶复合材料既具有橡胶的弹性，又有纤维的强度和刚度，制品具有高强度、高模量、耐撕裂、抗溶胀等优良性能，其复合材料已用于轮胎胎圈包布胶、三角胶、内衬层和胎面及胶管和输送带等产品。