轮胎与不平路面相互作用形成有效路面不平度的机理与应用分析

研究了轮胎与路面相互作用时有效路面不平度的形成机理,分析了有效路面谱计算方法及影响因素。研究表明,原路面不平度,路面压实量和轮变量是影响有效路面不平度的关键所在,举例说明了在车辆系统住址计算中有效路面谱的实际应用。     

荷载激励半刚性基层沥青路面声效响应分析

为了通过由沥青路面在冲击荷载作用下的声效特征差异识别路面层间连续状态,从而适时进行预防性养护,采用ABAQUS有限元从材料塑性变形、温度、土基等方面分析半刚性基层沥青路面不连续病害产生机制,建立半刚性基层沥青路面板体振动微分方程和强迫振动方程,求得其稳态解,并对板体振动时的声效响应及其敏感性因素进行分析。结果表明:激励荷载大小、板体尺寸、板体连续状态、不连续区域面积等较冲击加载方式、板体模量等因素对荷载激励产生声效特征响应更为强烈、敏感,板体振动声效特征频带基本集中在500 Hz之内;基于沥青路面在冲击荷载下因连续状态不同引起的声效特征差异性原理,开发的半刚性基层沥青路面结构层连续性检测仪的识别准确率达到96%。     

一种面向管道堵塞不均衡样本集的主动学习方法

针对城市排水管道堵塞检测识别过程中有标签的样本数量较少,人工标注管道数据样本成本高昂,以及管道堵塞数据集中存在明显的类别不均衡问题,提出基于主动学习的方法以解决上述问题.同时,将极限随机树作为基分类器,对未标注样本集进行分类识别;样本查询策略选择将分类熵和余弦相似度相结合的样本采样策略.该方法使得模型在主动学习的过程中...     

表面粗糙度对镍镀层结合性能的影响

对玻璃基双层镍表面进行阳极活化以提高镍层之间的结合强度。阳极活化液组成和工艺条件为:NiCl2·6H2O 100 g/L,H3BO3 25 g/L,pH 4.0,温度45°C,阳极电流密度10~30 mA/cm2,时间5~15 min。研究了电流密度和处理时间对镍镀层表面形貌、孤岛结合力、表面粗糙度和界面结合强度的影响,探讨了双层镍表面粗糙度和界面结合强度的关系。结果表明,在30 mA/cm2下阳极活化10 min后,双层镍的界面结合强度为629.8 MPa,比盐酸活化试样高了近2倍。镍层表面粗糙度与界面结合强度之间有明显的对应关系,表面粗糙度越大,界面结合强度越高。采用阳极活化法可有效提高微机电系统微器件的可靠性。     

浅谈钢结构表面处理处理的粗糙度

对钢结构防腐技术的研究表明：涂装前表面处理质量对涂层寿命（即防腐蚀效果）的影响最大。文章介绍了表面处理中对清洁度和粗糙度的要求,尤其就粗糙度的概念、作用、控制、评定等若干问题提出看法,供同行参考。     

微流道粗糙壁面对流动阻力和控制的影响

研究了3种粗糙单元(三角形、矩形、三角形与矩形交错混合)壁面对微流道内流动和摩擦阻力的影响。利用二维模型模拟了量纲一泊肃叶数与粗糙单元的几何特性和分布的关系。结果发现:在模拟条件下,粗糙壁面摩擦阻力(泊肃叶数)总是大于光滑壁面的摩擦阻力;壁面粗糙单元的高度对摩擦阻力的影响较大,可有近乎指数型的增长,粗糙单元的长度和间隔的影响居中,而雷诺数的影响较小。说明壁面粗糙度可有效改变槽道内的流动状态,增大混合效率。     

Scale-sensitive fractal analysis of the surface roughness of bloomed chocolate

The surface roughness of stored chocolate bars was studied by scanning laser microscopy and area-scale fractal analysis. Topographic data were expressed by the statistical average roughness (Sa), by two parameters from area-scale analyses—the fractal complexity (Asfc) and the scale of the rough-to-smooth transition (SRC)—and by the relative area as a function of scale. The roughness measured with Asfc showed extremely low correlation with the SRC, indicating that these two parameters can be considered to be independent. Asfc appeared to have some correlation (R ²=0.82) with the Sa, indicating that for these data Asfc and Sa are somewhat related. As surface roughness (Asfc) increased during storage, gloss decreased in a linear fashion (R ²=0.96), which is consistent with the proposal that surface roughness is intimately related to gloss. The scales of observation from about 0.5 to 100 μm² were characteristic of the fat bloom interaction with chocolate surface and with the gloss. Fractal analysis provides parameters (Asfc and relative area) that are better than conventional arithmetic mean roughness for describing the surface changes during storage of chocolate. Both the complexity (Asfc) and the relative areas showed strong correlations with gloss (0.96 and 0.94, respectively), which is consistent with a facet-based scattering model.     

Impact of deposit aging and surface roughness on thermal fouling: Distributed model

A kinetic model was recently proposed to describe the effect of aging on deposit thermal conductivity and the thermal performance of a shell‐and‐tube heat exchanger undergoing crude oil fouling. The model is adapted for implementation within a dynamic, distributed system with spatial and temporal distributions, relaxing several of the previous assumptions. The evolution of surface roughness is also considered, using conjectural linear and asymptotic functions. Simulations are performed for a single tube representative of a refinery exchanger. The results demonstrate the substantial effects over time of aging and roughness on heat transfer and pressure drop. Roughness effects yield apparently negative initial fouling resistances, as reported in some experimental tests. The importance of accounting for roughness dynamics in short time scale pilot plant scale tests and aging over longer time scales in industrial applications is highlighted. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

纳米碳酸钙的表面活化改性研究

本文主要介绍通过加入特定的表面改性剂,制得了表面改性的活性碳酸钙.并对活化过程中的一系列影响因素,如活化温度、活化时间、碳酸钙悬浊液浓度、表面改性剂用量进行了研究.     

Capillary bonding of wet surfaces - the effects of contact angle and surface roughness

Capillary bonding of wet solids through a water film is common and important for a variety of problems. An existing experimental technique for the measurement of capillary bonding forces was improved and used to show how fractional wetted area and capillary bonding force vary with water 'tension' for glass, polyethylene, and aluminum on porous ceramic. The effects of contact angle and roughness were explored. The results show that increasing the contact angle clearly reduces the capillary bonding, but the effects of surface roughness were much more complicated. Roughness can increase or decrease capillary bonding, depending on the exact conditions.     

Cohesive grains: Bridging microlevel measurements to macrolevel flow behavior via surface roughness

Significance Understanding fine‐particle flows relies on van der Waals cohesion modeling, requiring a method to consider measured surface roughness. A robust scheme to extract roughness parameters from AFM surface maps, achieving accurate predictions of microscale measured cohesion is proposed. Macroscale quantitative agreement is demonstrated by comparing defluidization predictions to measurements, which are sensitive to cohesion and system‐size independent. Agreement in both microscale and macroscale comparisons highlights the role of individual particle properties on bulk granular systems. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3529–3537, 2016     

The influence of some parameters on the surface roughness of thin copper foils using statistical analysis

The influence of nucleation potential, nucleation time, growth potential and substrate roughness on the surface roughness of thin copper foils deposited electrolytically on titanium substrates from a 83 g dm^–3 Cu²⁺ and 140 g dm^–3 H₂SO₄ solution at a temperature of 65 °C, using 2k⁴ factorial design, was studied. A mathematical model to determine the average surface roughness, a quality parameter of thin copper foils, was established. Statistical adjustment of the model enables its use in accurate prediction (error lower than 5%) of the average surface roughness of thin copper foils. The initial steps of copper nucleation and growth are particularly important for the quality of thin (18 m) copper foils, because during its manufacture, a rapid and homogeneous covering of the entire surface of the electrode becomes fundamental in order to obtain foils with a low surface roughness and a low degree of pinholes per unit area. Mechanisms for copper nucleation on titanium, based on the Thirsk and Harrison model for different experimental conditions, were determined with the aid of potentiostatic current transients. It was shown that the roughness of the thin copper foils is a function of not only the growth process, but also the nucleation process and that the lowest surface roughness is related to a pre-nucleation step at –0.590 V for 10 ms on a titanium substrate polished with 600-grit paper.     

Optical characterization of surface roughness of diamond by spectroscopic ellipsometry

Vacuum ultraviolet spectroscopic ellipsometry (SE) was performed on high-temperature and high-pressure (HPHT) synthesized Ib diamond samples with different polishing grades of different surface roughness, R_a [nm], which was measured by atomic force scanning microscopy (AFM). Observations showed that SE spectra systematically changed as a function of surface roughness. From this experimental result, we estimated the ideal dielectric function (DF) of diamond with a flat surface. Using this estimated DF, the optical thickness of a roughness layer was evaluated only from the SE data. It was shown that SE is an effective means of evaluating the thickness of a roughness layer and also the degree of surface modification without damaging the diamond surface, unlike the tip scanning of AFM measurements.