Building oriented surface generation through IGES specification

This thesis focuses the use of Initial Graphics Exchange Specification to generate automatically three dimensional surfaces. Currently, different CAD systems utilize their own data formats to generate graphic databases which are not compatible with one another. Besides, most of the existing CAD systems require an interactive data input process which is very much time consuming. In order to solve above problems, an efficient algorithm has been developed in this research to automatically generate portable graphic database following ICES specifications. This portable graphic database can be adopted by different commercial CAD/CAM systems. Using the proposed method, the current design process can be upgraded from the interactive data input method to automatic modelling method that accelerates design process in surface generation significantly. The main objectives of this research are: (1) curtail the surface generation time, (2) reduce the memory space for data storage and communication. A user-friendly program has been written in FORTRAN 77 to apply the proposed algorithm. A case study illustrates the effectiveness of the proposed method

A study of how Chinese ink painting features can be applied to 3D scenes and models in real-time rendering

Past research findings addressed mature techniques for non-photorealistic rendering. However, research findings indicate that there is little information dealing with efficient methods to simulate Chinese ink painting features in rendering 3D scenes. Considering that Chinese ink painting has achieved many worldwide awards, the potential to effectively and automatically develop 3D animations and games in this style indicates a need for the development of appropriate technology for the future market. The goal of this research is about rendering 3D meshes in a Chinese ink painting style which is both appealing and realistic. Specifically, how can the output image appear similar to a hand-drawn Chinese ink painting. And how efficient does the rendering pipeline have to be to result in a real-time scene. For this study the researcher designed two rendering pipelines for static objects and moving objects in the final scene. The entire rendering process includes interior shading, silhouette extracting, textures integrating, and background rendering. Methodology involved the use of silhouette detection, multiple rendering passes, Gaussian blur for anti-aliasing, smooth step functions, and noise textures for simulating ink textures. Based on the output of each rendering pipeline, rendering process of the scene with best looking of Chinese ink painting style is illustrated in detail. The speed of the rendering pipeline proposed by this research was tested. The framerate of the final scenes created with this pipeline was higher than 30fps, a level considered to be real-time. One can conclude that the main objective of the research study was met even though other methods for generating Chinese ink painting rendering are available and should be explored

A theoretical and experimental study of the mechanism of axoplasmic convection in nerve fibers driven by peristaltic surface waves

In the study of cell biology, investigators have found that substances which are produced within the cell nucleus are sometimes found throughout the cell at points distant from the site of production. In the case of nerve cells (neurons), this is particularly dramatic because of the unusual elongated geometry of these cells. A neuron possesses a cylindrical tubular extension called an axon or axis cylinder which is characterized by a large length-to-diameter ratio (103-106). The existence of a continuous proximo-distal flow of axoplasm within these cylindrical axons has now been demonstrated by numerous investigators. In this study, engineering techniques are employed to explore the role of microperistalsis as a possible driving mechanism for this axoplasmic flow. An experimental technique for injecting axons (5-10 microns-diameter) with micropipettes under visual microscopic control has been perfected. A new technique for microcapillary tube viscometric measurements applicable to micro samples of biological materials is presented. Using these techniques, a flow curve has been obtained for the axoplasmic substance. The results of these experiments indicate that axoplasin behaves as a highly viscous, pseudo-plastic material. No evidence of significant time-dependent thixotropic or viscoelastic effects was apparent. A theoretical analysis of the peristaltic pumping of pseudoplastic fluids at low Reynolds numbers by means of an infinite train of sinusoidal peristaltic waves is. presented. Results are shown as a series of pump characteristic curves involving the geometrical properties of tlie wave and the flow properties of the pseudo-plastic fluid as parameters. Data obtained from experiments performed on a plane, two-dimensional model are used to confirm the theoretical results. Cinemicrographic evidence reported in the literature describing waves traveling over the surface of axons in culture is discussed. A study of the geometrical properties of the peristaltic waves taken from these motion picture data is presented. The viscometric data obtained from axoplasm are used to establish system resistance curves for axons idealized as uniform cylindrical tubes. These data are correlated with the theoretical pump characteristic curves to determine an expected flow rate. A comparison between the theoretical flow rates and the observed axonal flow rates gives quantitative support to the hypothesis that peristalsis is the mechanism for axoplasmic flow. In addition, it is shown that the peristaltic pumping of a pseudoplastic fluid depends only on the geometrical properties of the peristaltic waves and the flow behavior index of the fluid. For this case of axoplasm, this indicates that the theoretical flow speed of axoplasm is independent both of the consistency of the axoplasmic material and the diameter of the axon

Minimizing structural vibrations with Input Shaping (TM)

A new method for commanding machines to move with increased dynamic performance was developed. This method is an enhanced version of input shaping, a patented vibration suppression algorithm. This technique intercepts a command input to a system command that moves the mechanical system with increased performance and reduced residual vibration. This document describes many advanced methods for generating highly optimized shaping sequences which are tuned to particular systems. The shaping sequence is important because it determines the trade off between move/settle time of the system and the insensitivity of the input shaping algorithm to variations or uncertainties in the machine which can be controlled. For example, a system with a 5 Hz resonance that takes 1 second to settle can be improved to settle instantaneously using a 0.2 shaping sequence (thus improving settle time by a factor of 5). This system could vary by plus or minus 15% in its natural frequency and still have no apparent vibration. However, the same system shaped with a 0.3 second shaping sequence could tolerate plus or minus 40% or more variation in natural frequency. This document describes how to generate sequences that maximize performance, sequences that maximize insensitivity, and sequences that trade off between the two. Several software tools are documented and included

ANALYSIS AND APPLICATION OF CAPACITIVE DISPLACEMENT SENSORS TO CURVED SURFACES

Capacitive displacement sensors have many applications where non-contact, high precision measurement of a surface is required. Because of their non-contact nature they can easily measure conductive surfaces that are flexible or otherwise unable to be measured using a contact probe. Since the output of the capacitance gage is electrical, data points can be collected quickly and averaged to improve statistics. It is often necessary for capacitive displacement sensors to gage the distance from a curved (non-flat) surface. Although displacements can easily be detected, the calibration of this output can vary considerably from the flat case. Since a capacitance gage is typically factorycalibrated against a flat reference, the experimental output contains errors in both gain and linearity. A series of calibration corrections is calculated for rectifying this output. Capacitance gages are also limited in their overall displacement travel. A support stage is described that, along with control electronics, allow the properties of the capacitance gage to be combined with an interferometer to overcome this displacement limitation. Finally, an application is proposed that would make use of the capacitance sensor and support stage assembly

Application of superconducting coils to the NASA prototype magnetic balance

Application of superconducting coils to a general purpose magnetic balance was studied. The most suitable currently available superconducting cable for coils appears to be a bundle of many fine wires which are transposed and are mechanically confined. Sample coils were tested at central fields up to .5 Tesla, slewing rates up to 53 Tesla/ sec and frequencies up to 30 Hz. The ac losses were measured from helium boil-off and were approximately 20% higher than those calculated. Losses were dominated by hysteresis and a model for loss calculation which appears suitable for design purposes is presented along with computer listings. Combinations of two coils were also tested and interaction losses are reported. Two feasible geometries are also presented for prototype magnetic balance using superconductors

Fluid mechanics of continuous flow electrophoresis

The following aspects of continuous flow electrophoresis were studied: (1) flow and temperature fields; (2) hydrodynamic stability; (3) separation efficiency, and (4) characteristics of wide gap chambers (the SPAR apparatus). Simplified mathematical models were developed so as to furnish a basis for understanding the phenomena and comparison of different chambers and operating conditions. Studies of the hydrodynamic stability disclosed that a wide gap chamber may be particularly sensitive to axial temperature variations which could be due to uneven heating or cooling. The mathematical model of the separation process includes effects due to the axial velocity, electro-osmotic cross flow and electrophoretic migration, all including the effects of temperature dependent properties

Graphical user interface for image processing

A user friendly, menu driven, highly interactive X Windows package for Image Processing Applications using Motif Widget Set under Motif Window Manager is developed. Modules related to Segementation, Enhancement, Representation, Transformations are developed. The above routines are useful for image manipulation. The current gray scale/binary image is displayed on the window. Online histogram is provided so that the user can change the threshold value interactively. The OSF/Motif toolkit is used efficiently and also Xlib calls to display the image by allocating colormap. An on-line image manipulation help menu facility is incorparated in the tool to make it more versatile