FIBSIM – dynamic Monte Carlo simulation of compositional and topography changes caused by focused ion beam milling

A new simulation program is presented for focused ion beam (FIB) induced sputtering in two-dimensional targets. The model combines dynamic Monte Carlo simulation of the collision cascades with cell-based topography simulation. This approach takes the nonlocal nature of the sputtering process into account, and treats doping, damage formation and compositional changes self-consistently with the evolution of the surface. Two applications are presented: erosion of a sample edge, and milling of a hole into a multilayer target.     

航天飞机雷达测图计划大块区域无效数据填补方法

在总结国内外对SRTM无效数据填补方法的基础上,针对直接用低精度的GTOPO30数据进行镶嵌填充SRTM无效数据会产生边界不光滑,细节表现不好的问题,采用Laplacian迭代修复算法。该算法是经典的基于偏微分方程(PDE)的图像修复算法。实例对比验证表明,该方法在对SRTM大块无效数据填补效果上明显好于用GTOPO30数据直接填补的效果,是获取完整SRTM数据的有效方法之一。     

双向A*算法在军事路径规划中的应用

为了解决军事地理信息系统（MGIS）中在野外无道路情况下的路径规划问题,对已有方法的不足进行了分析,基于军事地形学理论和人工智能（AI）启发式搜索算法（A*算法）,提出了一种可以满足实际军事行动需要的路径规划方法。在数字高程图（DEM）和其他图层共同组成的数字地形图（DTM）中进行实验,证明该算法能够有效地根据用户指定的通行条件规划出一条优化的实际可行的路径,并可以求出通行路径所用的路程和时间。算法分别用单向和双向两种方式实现,并比较了两种实现方式性能的差异和使用时机。     

The ocular surface status in individuals having long-term exposure to ionizing X-radiations

PurposeThe present investigation was done to assess the status of tear film and corneal topography in individuals with long-term exposure to X-ray.MethodThis historical cohort study was carried out to compare the lacrimal and corneal findings between radiographers (n = 126) and non-radiographers (n = 172). Radiographers included individuals with at least 5 years of experience in radiography while subjects in the control group had no history of exposure to X-ray. The Ocular Surface Disease Index (OSDI) was filled out by all individuals. Besides, the Pentacam imaging of both eyes was done. Finally, the lacrimal tests including tear break-up time and Schirmer (with anesthesia) were performed for both eyes of the participants.ResultsThe mean values of the Schirmer and Tear breakup time (TBUT) in the radiographer group (Schirmer: 11.1 ± 3.2 mm, TBUT: 11.3 ± 4.1 s) were significantly lower than the values in control group (14.6 ± 8.1 mm, TBUT: 12.8 ± 4.8 s) (P < 0.0001). The mean OSDI score of the radiographers was significantly higher compared to the control group (24.1 ± 17.6, and 12.3 ± 12.4 respectively (P < 0.0001)). The corneal thickness in the center, inferior, superior, temporal and nasal parts was significantly higher in radiographers versus the control group. In addition, the maximum thickness difference was observed in temporal part (34.00 μm thicker) (P < 0.0001). On the other hand, the corneal eccentricity factor was lower in radiographers compared to the control group (P < 0.0001).ConclusionBased on the findings of this study, it is concluded that the radiographers have thicker and flatter corneas are than the corneas of the subjects in the control group. However, their corneas had no irregularities. Regarding the tear point, a higher prevalence of dry eye symptoms was observed in the radiographers compared to the control group.     

Atomic force microscopy study on eucaryotic ribosomes

It is tried to compare the effects of sample preparation on shapes and sizes of ribosomes deposited on mica.The apparent sizes of ribosomes in the atomic force microscopy (AFM) images are about 60nm in most cases,The height appears to be indifferent to the sample preparation method and image conditions.It is found that the dehydration may greatly affect the topography of ribosomes.The volumes of ribosomes are estimated after considering the convolution effects of AFM tip on the appearance of ribosomes.     

Influence of surface topography on friction characteristics in wet clutch applications

In heavily loaded wet clutches, such as in limited slip differentials, sintered friction materials are sometimes used due to their resilience at high loads and high temperatures as well as their competitive cost in comparison to alternative friction materials.During the lifetime of the clutch, changes in the friction materials’ topography occur. These changes will influence the friction characteristics of the clutch, and therefore affect the anti-shudder performance of the transmission system. This paper investigates the influence of, and classifies, changes in the topography of the sintered friction material.The topography is measured by utilizing vertical scanning interferometry. Different parameters are investigated in order to find relevant parameters correlating to the wear of the material.Results show that changes in the topography of the friction material do indeed influence the friction characteristics of the clutch and that it is possible to calculate relevant topography parameters that describe the amount of wear the material has been subjected to.     

Internet-based surface metrology algorithm testing system

This paper presents the development of an Internet-based surface metrology algorithm testing system. The system includes peer-reviewed surface analysis tools and a surface texture specimen database for parameter evaluation and algorithm verification. The system runs from a web site at the National Institute of Standards and Technology (NIST), USA. Companies, universities, and instrument manufacturers have Internet access to standard data sets and analysis tools located on a NIST server. The system serves to validate the accuracy of algorithms as well as the calculation of surface parameters in industry.     

含高副平面运动链图及其拓扑图的自动生成

在对含高副平面运动链进行分析的基础上，本文提出了最大基环的概念，从而避免了杆与杆之间的交叉，并由计算机自动生成了八杆以内、１—３个自由度，含１—２个高副的平面运动链图及其拓扑图。     

分子沉积(MD)膜表面形貌的测量及影响因素

利用原子力显微镜 (AFM)考察了单层磺化酞菁铜 (CuTsPc)MD膜硅表面随载荷和扫描速率变化的盒维数 ,对单层CuTsPcMD膜硅表面进行了表面形貌的测量 ,并分析了形貌信息中的摩擦力信息对表面形貌信号的影响。结果表明 ,单层CuTsPcMD膜硅表面具有较好的分形几何特性 ,分形是表面的固有属性 ;不同类型的硅表面具有的盒维数基本不变。表面形貌的信息里包含的摩擦力信息是表面形貌测量中的重要影响因素 ,载荷和扫描速率通过影响摩擦力对表面形貌的测量产生影响 ,但载荷影响程度不大 ,且没有较明显的规律 ;扫描速率增加能引起表面粗糙度和表面高度的降低。