The technology of multi-axis machining has been applied extensively to the manufacturing of dies, molds, and various aerospace components. For machining mechanical parts with complex, sculptured surfaces, the use of multi-axis machine tools is probably the only one solution for avoiding tool-part collision during machining. Since cutting force will be changed by cutter attitudes, the machined surface characteristic can also be affected by cutter attitudes. In this thesis, the major concern is focused on investigating the effect of the cutter attitude on machined surface roughness. Based on the relationship between the cutter incline angle and the enveloped condition in cutting, the correlation of the mean chip thickness and the cutter incline angle is observed. To identify the relationship between the cutter attitude and the workpiece surface roughness, experimental verification is performed by milling aluminum alloy material. By fixing the cutting depths and the width of tool paths, different spindle rotational speeds and cutter incline angles are taken to machine the workpieces. And then, the machined surfaces are measured for their surface roughness. Form the experimental results, it shows that the surface roughness will reach a peak value at a special cutter incline angle. The tendency between the surface roughness and the incline angle agrees with that between the mean chip thickness and the cutter attitude approximately.

This thesis first presents a novel and highly accurate methodology for investigating the kinetics of photoacid diffusion and catalyzed-deprotection of positive-tone chemically amplified resists during post exposure bake (PEB) by in-situ monitoring the change of resist and capacitance (RC) of resist film during PEB. Deprotection converts the protecting group to volatile group, which changes the dielectric constant of resist. So the deprotection rate can be extracted from the change of capacitance. The photoacid diffusivity is extracted from the resistance change because diffusivity determines the rate of change of the acid distribution. Furthermore, by comparing the R and C curves, the dependence of acid diffusivity on reaction state can be extracted. The kinetics of non-Fickean acid transportation, deprotection, free volume generation and absorption/escaping, and resist shrinkage is analyzed and a comprehensive model is proposed that includes these chemical/physical mechanisms. Then in this thesis a novel lithographic technique, liquid immersion contact lithography (LICL) is proposed and the simulations are performed to illustrate its main features and advantages. Significant depth-of-field (DOF) enhancement can be achieved for large pitch gratings with deep-UV light (λ=248nm) illumination with both TM and TE polarizations by liquid immersion. Better than 100nm DOF can be achieved by when printing 70nm apertures. The simulation results show that it is very promising to apply this technique in scanning near field optical microscopy. Finally, a rigorous, full vector imaging model of non-ideal mask is developed and the simulation of the imaging of such a mask with 2D roughness is performed. Line edge roughness (LER) has been a major issue limiting the performance of sub-100nm photolithography. A lot of factors contribute to LER, including mask roughness, lens imperfection, resist chemistry, process variation, etc. To evaluate the effect of mask roughness on LER, a rigorous full vector model has been developed by the author. We calculate the electromagnetic (EM) field immediately after a rough mask by using TEMPEST and simulate the projected wafer image with SPLAT. The EM field and wafer image deviate from those from an ideal mask. LER is finally calculated based on the projected image.

No description available.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 87-91). Also available on the Internet.

The flow of fluids over solid surfaces is an integral part of many technologies, and the analysis of such flows is important to the design and operation of these technologies. Solid surfaces, however, are generally rough at some scale, and analyzing the effects of such roughness on fluid flows represents a significant challenge. There are two fluid flow situations in which roughness is particularly important, because the fluid shear layers they create can be very thin, of order the height of the roughness. These are very high Reynolds number turbulent wall-bounded flows (the viscous wall layer is very thin), and very low Reynolds number lubrication flows (the lubrication layer between moving surfaces is very thin). Analysis in both of these flow domains has long accounted for roughness through empirical adjustments to the smooth-wall analysis, with empirical parameters describing the fluid dynamic roughness effects. The ability to determine these effects from a topographic description of the roughness is limited (lubrication) or non-existent (turbulence). The commonly used parameter, the equivalent sand grain roughness, can be determined in terms of the change in the rate of viscous energy dissipation caused by the roughness and is generally obtained by measuring the effects on a fluid flow. However, determining fluid dynamic effects from roughness characteristics is critical to effective engineering analysis. Characterization of this mapping from roughness topography to fluid dynamic impact is the main topic of the dissertation. Using the mathematical tools of shape calculus, we construct this mapping by defining the roughness functional and derive its first- and second- order shape derivatives, i.e., the derivatives of the roughness functional with respect to the roughness topography. The results of the shape gradient and complete spectrum of the shape Hessian are presented for the low Reynolds number lubrication flows. Flow predictions based on this derivative information is shown to be very accurate for small roughness. However, for the study of high Reynolds number turbulent flows, the direct extension of the current approach fails due to the chaotic nature of turbulent flows. Challenges and possible approaches are discussed for the turbulence problem as well as a model problem, the sensitivity analysis of the Lorenz system. / text

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It is known that a phase-perturbed object field from a fractal-like rough surface illuminated by a partially coherent beam generates speckle on the image plane. In this works, aberration effects on Gaussian speckle on the image plane in both perfectly and partially coherent systems are theoretically and experimentally investigated. Theory shows that the second order statistics of Gaussian laser speckle are independent of odd-functional aberrations, but they do affect Gaussian speckle contrast in a partially coherent system. Furthermore, it is theoretically derived that field statistics of Gaussian laser speckle generally become non-circular Gaussian due to aberrations, and an aberration effect is asymptotically ignorable for very weak or strong roughness. A brute force simulation method is introduced for non-Gaussian speckle in a partially coherent imaging system, where speckle irradiance is calculated from a quasi-monochromatic extended incoherent source. The source is modeled as a collection of independent point sources distributed on a regular grid. The partially coherent speckle pattern is calculated from the incoherent sum of coherent speckle patterns in the image plane generated from each point source. Speckle contrasts from a brute force model show good agreement with theoretical and experimental results. It is determined that non-Gaussian speckle contrast is strongly dependent on Hurst exponent of fractal rough surfaces using brute force simulations. The concept of a contributing object area at a fixed image point effectively explains the speckle contrast dependency. Measuring spherical aberrations using Gaussian laser speckle is discussed as one of applications and future works of the present study.

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New nanomaterials and nanoparticles are currently under investigation as lubricants or lubricant additives due to their unusual properties compared to traditional materials. One of the objectives of this work is to investigate the tribological properties of these materials in relation to surface topography. Chemical etching and metal evaporation methods were employed to prepare surfaces with various topographies. Surfaces were sheared with the use of a nanotribometer and characterized with an atomic force and scanning electron microscopes. For a system consisting of ZnS nanowires dispersed in dodecane sheared across ductile surfaces, it was found that the geometry of the nanowire relative to the surface topography plays a significant role. Moreover, for brittle surfaces, it was found that beyond a certain roughness the frictional properties remain unchanged. In addition, this work is also intended to explore novel lubricants with nanoparticle additives in efforts to control friction and wear. A system consisting of silica nanoparticles dispersed in ionic liquids was examined at various concentrations. It was found that an optimum concentration of nanoparticles exists and yields the best tribological properties. Such work represents an important step in understanding the tribological properties of nanoparticle lubricant additives in general; one that may ultimately provide the guidelines necessary for designing novel, low-friction, and wear-controlling nanoparticle-based lubrication systems that minimize energy and material losses due to friction.

From previous research, it has been proven that rock roughness and closure are two important factors for stability of backfilled stope and exposed backfill. In order to estimate the important parameters of roughness, several investigations have been conducted in other scientific fields to study roughness. The results showed that the important roughness parameters are application-dependent. In geology and rock mechanics the Joint Roughness Coefficient (JRC) is a critical factor that incorporates the roughness in stability problems. Although JRC is widely used, it is very subjective and highly depends on the experience of the individual conducting the analysis. During the last several decades there were attempts to use different methods such as fractal geometry, Fourier analysis, analytical methods, etc. to convert a random surface profile into a JRC. The goal of the current research is to estimate with greater accuracy the contribution of roughness to the shear strength of the interface at the paste-rock contact when backfilling. Four hundred and fifty backfill samples were constructed and tested in a shear box. The variables of the tests are three: binder percentage, roughness and cure time. From the test results the importance of each of those parameters to the final shear strength of the paste-rock interface was estimated. The normal stress that acts on the samples is also a critical factor. From the tests that were tried, it was concluded that there are limits in normal stress for which roughness is important. / Thesis (Master, Mining Engineering) -- Queen's University, 2009-08-27 16:07:21.916