Surface topography

The diagnostic study of spinal deformities has long been a focus of medical science. For a clear condition assessment of scoliotic patients X-ray images are used. Disadvantages of X-ray inspections, however, make methodological research, which can lead to fast and cost-efficient examinations without harmful radiation, reasonable. HISTORY: In 1874, after LORD RAYLEIGH had studied the resultant pattern, the so-called moiré fringes of two overlapping grids, he concluded that the phenomenon could be useful for measurement purposes. Beyond industrial applications further research, about a hundred years later, proposed moiré topography for measurement of the human body. AIMS AND METHODS: The aim of this publication, based on thorough study of resources, is to present the basic theory of the moiré method and its application in scoliosis. The two main methods − the shadow and projection moiré − of moiré technique are described in detail. Moreover, the paper presents KAMAL's algorithm suggesting to calculate the plane angle of curvature in single-curve scoliosis cases and proposes directions for further research and developments. RESULTS: The significant advantages of the moiré method are that it is fast, non-invasive, portable, cost-efficient and has no harmful radiation. A moiré technique chosen and algorithmized well can be convenient for substitution or as a complement of X-ray images in scoliosis. However, it is a limitation that a methodological standard which could lead to generally reliable results has not been created yet. Furthermore, the amount of labour required for the evaluation of moiré images is not inconsiderable. To achieve further success of the moiré method a dedicated partnership of engineers and physicians, respectively the application of technical-biomedical knowledge is needed.

Abstract: Purpose: To rationalize the use of surfactants by preparing Salbutamol sulphate microspheres using two types of surfactants, Tween 80 and Span 80 and study their effects on different characteristics of the microspheres. Methods: Microspheres containing Salbutamol sulphate was ...

We describe several examples where we use cross-correlation functions to quantify the similarity of 2D surface profiles or of 3D areal surface topography images. The applications have included (1) the manufacture of standard reference material (SRM) bullets and casings, (2) methods to assess whether bullets or casings have been fired by the same firearm, and (3) research to quantify similarities or differences between profiles of the same surface measured by different techniques or between a master surface and its replicas. The cross-correlation maximum is the functional parameter used to quantify similarity. A second parameter, called the relative profile (2D) difference or relative areal topography (3D) difference, may also be used to quantify differences and to recognize the ambiguous condition when two results have different vertical (z-) scales but identical shapes. Most of these examples have been applied in support of ballistics inspection methods in crime labs, but the methods are generally useful for estimating the accuracy of surface replication techniques or the ability of different surface topography instruments to measure the same surface and provide the same result. The instruments used in these studies were a stylus instrument and a Nipkow-disk type confocal microscope. Cross-correlation functions may also be used to assess differences resulting from the use of different filters to modify the same surface profile or topography image.

X-ray fluorescence spectrometry is a common technique in determining the elemental composition of lithic materials. With the exception of glassy volcanic rocks like obsidian, most rock types are prepared for analysis by conversion of specimens to powder or glass in order to reduce the effects of irregular surface topography and internal inhomogeneity. Concern for artefact conservation necessitates a less destructive

Engine downsizing is desired for modern heavy-duty vehicles to enhance fuel economy and reduce emissions. However, the smaller engines usually cannot overcome the parasitic loads during engine start-up. A new clutch system is designed to disconnect the downsized engine from the parasitic losses prior to the idling speed. A multi-scale, multi-physics model is developed to study the clutch system. Multi-body dynamics is used to study the combined translational-rotational motions of the clutch components. A micro-scale contact model is incorporated to represent the frictional characteristics of the sliding surfaces. Although the clutch is designed for dry contact operation, leakage of actuating hydraulic fluid can affect the interfacial frictional characteristics. These are integrated into the multi-body dynamic analysis through tri-bometric studies of partially wetted surfaces using fresh and shear-degraded lubricants. Multi-scale simulations include sensitivity analysis of key operating parameters, such as contact pressure. This multi-physics approach is not hitherto reported in the literature. The study shows the importance of adhesion in dry clutch engagement, enabling full torque capacity. The same is also noted for any leakage of significantly shear-degraded lubricant into the clutch interfaces. However, the ingression of fresh lubricant into the contact is found to reduce the clutch torque capacity.

Determination of dry pressure drops is often the preliminary diagnostic tool for characterizing structured packing-containing columns. One conventional approach that ushered in this area evolves around the use of Ergun expressions along with mandatory experimental pressure drops for the fitting of some empirical constants characterizing a given packing. This method is strictly representational, and incapable of predicting the impact on

Three-dimensional surface roughness of mating parts of engineering assemblies has a significant influence on their functional behaviour. Studies on load bearing capacity in elastohydrodynamic contacts, gap flow analysis in precision hydraulic assemblies using modeled 3D fluid continuum micro gap geometry, etc., have made it possible to quantify the effect of certain 3D surface roughness parameters on frictional behaviour of the assemblies. This set forth the need for artificially generated three-dimensional engineering surfaces having prescribed roughness values for a better understanding and prediction of tribological problems. In this paper, an algorithm is developed for the numerical generation of three-dimensional anisotropic surfaces with prescribed 3D surface roughness parameters. The procedures employ either the Non-linear Conjugate Gradient Method (NCGM) or 2-D Digital Filter method. The results show that both the methods can adequately produce surfaces at small correlation distances, while at higher correlation distances the NCGM yields better results. Comparison between model-simulated output and measurement results of three-dimensional surface roughness of engineering surface show a good match, supporting the validity of the model.

Although surface finish can be a critical variable in clinical performance, there is a dearth of information regarding surface characteristics of teeth prepared for artificial crowns. This study characterized teeth prepared for complete cast restorations using three representative types of rotary instruments. One hundred and five standardized tooth preparations for complete crowns were performed using a modified milling machine on extracted human teech with diamond, tungsten carbide, and tungsten carbide finishing burs of similar shape (n = 35). The prepared dentin was analyzed with a surface profilometer and a scanning electron microscope (SEM). Differences between rotary instrument groups were determined with parametric ANOVA and Tukey's Studentized Range (HSD). Statistically significant differences in the surface topography of prepared teeth were seen. Mean surface roughnesses (Ra) were 8.6 and 6.8 μm for teeth prepared with diamond and tungsten carbide burs. Teeth completed with finishing burs appeared to result in a smoother surface (1.2 μm).

While there has been significant progress in the treatment of ischemic heart failure, it remains a significant health and economic problem worldwide. In this paper, we present the challenges of modelling ischemic heart failure and introduce a user-friendly software system that will be a sub-set of the Virtual Pathological Heart environment which is currently being developed under the FP7 VPH2