Evolution of Generic Mathematical Models and Algorithms for the Surface Development and Manufacture of Complex Ducts

1995 ◽  
Vol 117 (2) ◽  
pp. 177-185 ◽  
Author(s):  
P. Sundar Varada Raj
Keyword(s):  
Mathematical Models ◽  
Cross Sections ◽  
Physical Modelling ◽  
Theoretical Determination ◽  
Spline Curve ◽  
Developable Surfaces ◽  
Surface Development ◽  
Cutting Out ◽  
Cad Cam

Complex ducts bound by developable surfaces can be obtained by cutting out the required developed shape on plane sheets and then wedge-bending or folding along certain lines called generators or rulings. The problem then reduces to the theoretical determination of the 2-D shape to be cut so that on folding along the rulings, the required 3-D surface is accurately obtained. The first step in the surface unfolding process is the determination of the parametric β-θ relationship between two adjacent cross-sections of the duct. The cross-sections of the duct can be planar or nonplanar and composed of conic or spline curve segments, placed anywhere in space. In this paper the requisite β-θ relationships of the most generic form have been derived and can be directly applied to any complex duct. Based on these relationships, an efficient and compact algorithm for surface-unfolding has also been derived. The application of this algorithm to numerous prototype cases has been shown. The theory has been verified by physical modelling of various ducts occurring in the field of hydroturbines, and now forms the basis of an Integrated CAD-CAM System.

ANALYSIS OF THE IMPACT OF BIOMATERIAL AND THE TECHNOLOGY OF PROSTHETIC CROWNS MANUFACTURING ON THE CONNECTION WITH VENEERING CERAMICS

Tribologia ◽  
2021 ◽  
Vol 293 (5) ◽  
pp. 17-25
Author(s):  
Anna M. RYNIEWICZ ◽  
Andrzej Ryniewicz ◽  
Łukasz Bojko ◽  
Wojciech Ryniewicz
Keyword(s):  
Penetration Depth ◽  
Cross Sections ◽  
Glass Ceramic ◽  
Testing Machine ◽  
Layered Structures ◽  
Micro Hardness ◽  
Hardness Tester ◽  
Cad Cam ◽  
The Impact

The aim of the study is to identify the endurance parameters of prosthetic crowns veneered with dedicated ceramics on metal, glass-ceramic, and ceramic frameworks. Metal frameworks were made using CAD/CAM milling technology and SLM technology, while the glass-ceramic and ceramic frameworks were produced using only the CAD/CAM milling technology. The research materials are samples replicating the layered structures of prosthetic crowns. The veneering procedure must ensure the adhesion of the ceramics to the loadbearing framework. The tests modelling the conditions of concentrated loads during chewing were carried out using the Instron 3345 testing machine. Determination of microhardness in cross-sections through layered structures of crowns was performed using the HMV Micro Hardness Tester. The comparison of force loading the indenter as a function of penetration depth indicates that the value of the maximum depth depends on the configuration of microhardness of the framework and dentine. The zirconium ceramics ZrO2 (3Y-TZP) – veneered with Elephant Sakura silica ceramics – should be indicated as the most advantageous material composition.

Theoretical determination of bound–free absorption cross sections in Ar+2

1977 ◽  
Vol 67 (6) ◽  
pp. 2860 ◽  
Author(s):  
Walter J. Stevens ◽  
Maureen Gardner ◽  
Arnold Karo ◽  
Paul Julienne
Keyword(s):  
Cross Sections ◽  
Absorption Cross ◽  
Theoretical Determination

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

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