Smoothed Surfaces Research Articles

Evaluation of Relation between Friction Coefficient and Oil Film Thickness of Ground Gear

Matsumoto's equation, which determines the ratio of the friction coefficient between boundary lubrication and fluid lubrication by the ratio of the maximum height roughness and minimum oil film thickness, is often used to predict the friction coefficient on gear tooth surfaces. Recently, however, several papers using gears with highly smoothed tooth surfaces have reported discrepancies between the measured friction coefficient of tooth surface and Matsumoto's equation. It seems that the problem of how to determine the boundary lubrication friction coefficient lies behind these discrepancies. In this paper, the coefficient of tooth friction is determined under a wide range of lubrication conditions using ground spur gears, and the experimental results are compared with the calculation results of Matsumoto's equation to reevaluate the relationship between the two. The friction coefficient of boundary lubrication was found to vary with surface roughness of tooth surface.

Computer Modelling And Experimental Research of Led Optical Systems

The paper considers the problem of design of modern light devices (LDs) based on LEDs and their optical systems (OSs). LEDs optical systems provide developers with opportunities to implement a variety of modern lighting tasks. In the market of competing products, it is often necessary to calculate and produce LED optics for specific lighting problems. The main one is the formation of a given distribution of illumination over the surface of the object. In comparison with existing lens and reflective OSs, individual projects with their own developed elements can give the desired result. The most popular services in LED lighting are the development of LED optics according to the customer’s specifications, lighting of the simulated product, development of 3D models for further production. The main stage in its development is the calculation and modelling of the OS. The results of this process are largely determined by the complex of lighting, thermal and functional characteristics of LDs. The development of modern LED LDs is inextricably linked with the use of specialized software. The article describes a mathematical model of the geometry of an OS that allows researcher to specify its shape for further design and provides a fast and accurate lighting calculation. To model objects, triangulation grids are often used, which makes it possible to fine tune their shape. To simplify the process of forming smoothed 3D surfaces, an edge was introduced as an auxiliary element of a triangulation grid. It makes it possible to simplify the process of approximating smooth surfaces without increasing the density of this grid. The developed software allows you to build optical surface models, perform ray tracing and calculate photometric body (PB). The article describes the simulation of LED OSs by the example of secondary LED optics. Computer simulation and prototyping of LED modules (LEDMs) for road lighting was carried out. 3D-models, a PB and curves of luminous intensity of LEDMs are received. The thermal imager an experimental study of the luminous and thermal characteristics of these modules was carried out. The results of the experiment showed very good agreement with the calculated models.

Terror Terroir: Building Disruptive Possibilities in Ivan Vladislavić’s The Folly

Summary Ivan Vladislavić’s 1993 novel The Folly has received less critical attention than his other writing. The novel was republished recently and, in this article, I read The Folly as a text that, from the vantage point of 1993, stages white South African suburbia as a site fraught with tensions. In the novel, the appearance of a drifter on a terrain vague dissolves the certainties of a suburban neighbourhood, creating an inchoate but gnawing sense of threat that finds expression in the Malgas family. I argue that white suburbs are under-examined cultural sites whose mundanity disguises their disci- plining principles. I draw on experiences of inhabiting ‘white space’ as a Black person to read Vladislavić’s novel as parodying white unease towards spaces that disrupt the taut or smoothed surfaces of suburbia. This unease is reflected most visibly in the post-apartheid evolution of such suburbs into lifestyle clusters, security estates and other configurations of life that are arranged around the alleviation of white middle- class anxieties.

Room-temperature wafer scale bonding using smoothed Au seal ring surfaces for hermetic sealing

We evaluated room-temperature bonding characteristics of electroplated Au surfaces smoothed by the lift-off and imprint methods. As a result, we found that smoothed surfaces enable strong bonding; on the other hand, electroplated rough surfaces result in very weak bonding. In transmission electron microscopy observations, no delamination was observed at the bonding interface bonded at room temperature using a smooth surface prepared by the lift-off method. Moreover, the hermeticity of the bonding interface prepared using smoothed surfaces was evaluated using diaphragm structures. As a result, we confirmed that good hermetic sealing was achieved using the electroplated Au surface smoothed by the lift-off method.

Individual-level space-time analyses of emergency department data using generalized additive modeling.

BackgroundAlthough daily emergency department (ED) data is a source of information that often includes residence, its potential for space-time analyses at the individual level has not been fully explored. We propose that ED data collected for surveillance purposes can also be used to inform spatial and temporal patterns of disease using generalized additive models (GAMs). This paper describes the methods for adapting GAMs so they can be applied to ED data.MethodsGAMs are an effective approach for modeling spatial and temporal distributions of point-wise data, producing smoothed surfaces of continuous risk while adjusting for confounders. In addition to disease mapping, the method allows for global and pointwise hypothesis testing and selection of statistically optimum degree of smoothing using standard statistical software. We applied a two-dimensional GAM for location to ED data of overlapping calendar time using a locally-weighted regression smoother. To illustrate our methods, we investigated the association between participants’ address and the risk of gastrointestinal illness in Cape Cod, Massachusetts over time.ResultsThe GAM space-time analyses simultaneously smooth in units of distance and time by using the optimum degree of smoothing to create data frames of overlapping time periods and then spatially analyzing each data frame. When resulting maps are viewed in series, each data frame contributes a movie frame, allowing us to visualize changes in magnitude, geographic size, and location of elevated risk smoothed over space and time. In our example data, we observed an underlying geographic pattern of gastrointestinal illness with risks consistently higher in the eastern part of our study area over time and intermittent variations of increased risk during brief periods.ConclusionsSpatial-temporal analysis of emergency department data with GAMs can be used to map underlying disease risk at the individual-level and view changes in geographic patterns of disease over time while accounting for multiple confounders. Despite the advantages of GAMs, analyses should be considered exploratory in nature. It is possible that even with a conservative cutoff for statistical significance, results of hypothesis testing may be due to chance. This paper illustrates that GAMs can be adapted to measure geographic trends in public health over time using ED data.

Soil surface roughness measurement—methods, applicability, and surface representation

In a laboratory rainfall simulator study soil surface roughness was measured using contact (roller chain, pin meter) and noncontact devices (laser scanner, photogrammetry). Soil surfaces with two initial roughness conditions (aggregates < 20 mm and < 63 mm) were investigated before and after 90 mm of simulated rainfall. Measured plot area was 50 by 55 cm. A comparison of soil roughness measurement techniques was undertaken with regard to data acquisition and computation efforts, resolution, precision and capability to represent soil surface features. As for the contact methods, resolution (cm range) and precision (mm range) is limited which constrains their application to calculation of simple surface parameters. Resolution and precision in the sub millimeter range could be obtained with the laser scanner, while for the photogrammetric method the measurement uncertainty was approximately 1–2 mm. Measurement time was highest (90 min) for the pin meter technique, though data were ready to use for analyses. Laser scanner measurements took 34 min. Several steps of data post-processing required 30 more minutes. Data acquisition was fastest for photogrammetry (5 min), but expert knowledge as well as special hard- and software were necessary for time-consuming photo analyses, taking about 120 min. The chain and pin meter were compared using a profile index. Profile lengths matched well for smooth surfaces; on rough surfaces, the chain meter gave shorter profile lines. Between profile index from chain measurements and the random roughness derived from pin meter data a polynomial regression could be found. Parameters of distributions of elevations as well as inclinations and depressions were used to compare the laser scanner and the photogrammetric technique. Generally the laser scanner was able to reproduce small aggregates as well as voids in between them, while DEM from stereophotos was smoothed between major aggregates. This led to skewed distributions of elevations and inclinations, as well as to a lower surface area (up to 39%), and a lower depression volume (up to 68%). Shapes of depressions were significantly different as well. The used photogrammetric technique is supposed to be successful in producing adequate DEMs for already smoothed surfaces, e.g. after rainfall events. The study revealed different fields of application and limitations of the compared devices. Using a non-adequate technique for certain situations will definitely have implications on further analyses concerning connectivity of runoff pathways, surface protection from raindrop impact or runoff detachment and sediment transport.

Fabrication of poly(methyl methacrylate) microfluidic chips by atmospheric molding.

A greatly simplified method for fabricating poly(methyl methacrylate) (PMMA) separation microchips is introduced. The new protocol relies on UV-initiated polymerization of the monomer solution in an open mold under ambient pressure. Silicon microstructures are transferred to the polymer substrate by molding a methyl methacrylate solution in a sandwich (silicon master/Teflon spacer/glass plate) mold. The chips are subsequently assembled by thermal sealing of the channel and cover plates. The new fabrication method obviates the need for specialized replication equipment and reduces the complexity of prototyping and manufacturing. Variables of the fabrication process were assessed and optimized. The new method compares favorably with common fabrication techniques, yielding high-quality devices with well-defined channel and injection-cross structures, and highly smoothed surfaces. Nearly 100 PMMA chips were replicated using a single silicon master, with high chip-to-chip reproducibility (relative standard deviations of 1.5 and 4.7% for the widths and depths of the replicated channels, respectively). The relatively high EOF value of the new chips (2.12 x 10(-4) cm(2) x V(-1) x s(-1)) indicates that the UV polymerization process increases the surface charge and hence enhances the fluidic transport. The attractive performance of the new CE microchips has been demonstrated in connection with end-column amperometric and contactless-conductivity detection schemes. While the new approach is demonstrated in connection with PMMA microchips, it could be applied to other materials that undergo light-initiated polymerization. The new approach brings significant simplification of the process of fabricating PMMA devices and should lead to a widespread low-cost production of high-quality separation microchips.

Electrochemical Properties of Ar+ Sputtered Polycrystalline Diamond Electrodes with Smoothed Surfaces

Abstract The initial rough, faceted surfaces of boron-doped conductive polycrystalline diamond electrodes were smoothed by Ar+ ion sputtering at very low energy (50 eV). A lower background current was measured at the modified electrodes with a mirror-like appearance than at the initial polycrystalline electrodes. The electrochemical responses to several redox systems also showed a morphological-dependence in some cases. Here, we discuss the electrochemical properties of the diamond electrodes with the smoothed surfaces from the point of view of a novel electrode material.

Erosion by pyroclastic flows on Lascar Volcano, Chile

Pyroclastic flows generated in the 19–20 April 1993 eruption of Lascar Volcano, Chile, produced spectacular erosion features. Scree and talus were stripped from the channels and steep slopes on the flanks of the volcano. Exposed bedrock and boulders suffered severe abrasion, producing smoothed surfaces on coarse breccias and striations and percussion marks on bedrock and large boulders. Erosional furrows developed with wavelengths of 0.5–2 m and depths of 0.1–0.3 m. Furrows commonly nucleated downstream of large boulders or blocks, which are striated on the upstream side, and thereby produced crag-and-tail structures. Erosive features were produced where flows accelerated through topographic restrictions or where they moved over steep slopes. The pyroclastic flows are inferred to have segregated during movement into lithic-rich and pumice-rich parts. Lithic-rich deposits occur on slopes up to 14°, whereas pumice-rich deposits occur only on slopes less than 4°, and mainly at the margins and distal parts of the 1993 fan. The lithic-rich deposits contain large (up to 1 m) lithic clasts eroded from the substrate and transported from the vent, whereas pumice-rich deposits contain only small (typically <2 cm) lithic clasts. These observations suggest that lithic clasts segregated to the base of the flows and were responsible for much of the erosive phenomena. The erosive features, distribution of lithic clasts and deposit morphology indicate that the 1993 flows were highly concentrated avalanches dominated by particle interactions. In some places the flows slid over the bedrock causing abrasion and long striations which imply that large blocks were locked in fixed positions for periods of about 1 s. However, shorter striae at different angles, impact marks, segregation of the deposits into pumice- and lithic-rich parts, and mixing of bedrock-derived lithic clasts throughout the deposits indicate that clasts often had some freedom of movement and that jostling of particles allowed internal mixing and density segregation to occur within the flows.

3D colour visualization of label images using volume rendering techniques.

Volume rendering methods for the visualization of 3D image data sets have been developed and collected in a C library. The core algorithm consists of a perspective ray casting technique for a natural and realistic view of the 3D scene. New edge operator shading methods are employed for a fast and information preserving representation of surfaces. Control parameters of the algorithm can be tuned to have either smoothed surfaces or a very detailed rendering of the geometrical structure. Different objects can be distinguished by different colours. Shadow ray tracing has been implemented to improve the realistic impression of the 3D image. For a simultaneous representation of objects in different depths, hiding each other, two types of transparency mode are used (wireframe and glass transparency). Single objects or groups of objects can be excluded from the rendering (peeling). Three orthogonal cutting planes or one arbitrarily placed cutting plane can be applied to the rendered objects in order to get additional information about inner structures, contours, and relative positions.

Comparison of the smoothing and shaping of optics by plasma-assisted chemical etching and ion milling using the surface evolution theory

Plasma-assisted chemical etching (PACE) and ion milling (IM), originally developed for microelectronic fabrication, can now be used to shape or figure and smooth or polish optical and other surfaces with the unique advantage of doing so without mechanical contact. Using a recent theory of the temporal evolution of surfaces that is due to arbitrary additive or subtractive microscopic processes, the author critically compares the predicted and observed smoothing of PACE and IM in this paper to provide insight into their smoothing and other behavior. PACE removes > 10 mm(3)/min and smooths surfaces of considerable roughness (> 10-µm rms). It has produced smoothed surfaces to < 1.0-nm rms without generating electronic subsurface damage. The IM removal rate is > 10(3) times slower, is used primarily for making corrections of less than a micrometer, intrinsically generates electronic subsurface damage, and furthermore requires starting with a smooth surface (≈ 1.0 nm) to maintain smoothness. Both PACE and IM remove mechanical subsurface damage. In agreement with observation, it is shown theoretically that the central distinction between PACE and IM stems from substantial differences in their intrinsic smoothing.

Surface textures and rounding of quartz sand grains on intertidal sandbars, Bay of Fundy, Nova Scotia

Intertidal sands in the Minas Basin are mineralogically immature, and are generally medium grained and moderately well sorted. Quartz grains show a wide range of roundness: mean roundness is subangular, but rounded to well rounded grains are also present. The sands are derived mainly from coastal erosion of Pleistocene tills and outwash and Triassic sandstones.Scanning electron microscope examination of the surface textures of more than 40 samples of source materials and tidal sands reveals that although many of the textures are relict, tidal sands show high, smoothed surfaces with non-oriented V's, and low areas with 'patchy growths', neither of which are present on source sands. Rounding of grains is undoubtedly taking place in the tidal environments, but much of the roundness is inherited from Triassic source material, and new surface textures are developed most rapidly on grains already partly rounded.Average distances of grain transport in the layer of sand moving on the bar surface is of the order of 1 m per tidal cycle, and allowing for reworking of the entire mass of sand in the bars, this results in a long term transport rate of only about 10 m per year. For the distance of transport, sediment transport by tides is probably more efficient at rounding sand grains than transport by rivers, but less efficient than transport by waves or wind. Geologically long periods of reworking by tides would be necessary to produce texturally supermature sands.

Corrosion and Corrasion on Barton Creek, Austin, Texas

At a locality on Barton Creek, near Austin, Texas, the stream flows across horizontal layers of alternating hard and soft limestone. The bed-rock channel is incised by a number of long parallel grooves whose smoothed surfaces and U-shaped profiles are interpreted as a result of corrasion. On higher benches similar grooves occur at levels not now reached by the water of the stream, which are now being corroded by standing water, resulting in pitting of their smooth surfaces and in the formation of flat-floored, steep-walled basins known as tinajitas or etched potholes. The origin of the tinajitas is discussed. It is concluded that the features described are a result of the downward cutting of a youthful stream in a semi-arid climate, with a change from corra-sive work to corrosive work on the valley-side benches as the stream cuts below them.