Study of Contact Parameters in Metal-on-plastic Hip Endoprothesis with a New Analytical Method of Contact Mechanics

Author(s):  
Myron Chernets ◽  
Jaroslaw Zubrzycki

Author(s):  
Raja R. Katta ◽  
Andreas A. Polycarpou ◽  
Jorge V. Hanchi

A contact mechanics-based elastic-plastic impact model which considers slider corner – head disk interaction has been proposed. This model estimates the impact contact parameters accounting for the plastic deformation effects of the realistic thin-film disk media. These properties were utilized for the elastic-plastic impact model to estimate the contact parameters. Very high impact velocities and/or small slider corner radii resulted is extremely high contact depths where the disk substrate mostly dominated the impact and the effect of layers could not be seen. At lower impact velocities and higher corner radii, the impact damage was relatively smaller. The effect of the thin-film layers, which are stiffer than the substrate, was clearly observed.



Author(s):  
Lior Kogut ◽  
Robert L. Jackson

Statistical and fractal approaches for characterizing surface topography have been used widely in contact mechanics. In the present study, an attempt is made to compare between contact mechanics results obtained with statistical and fractal approaches to characterize surface topography. Specifically, a three-dimensional fractal surface was generated and statistical surface parameters were extracted using different sampling resolutions. Contact mechanics simulations were performed using the simulated fractal surface and statistical surfaces represented by the extracted statistical surface parameters. Purely elastic contact is studied in order to eliminate the influence of the individual asperity mechanical response on the obtained results. Therefore, differences in the simulated contact area and load can be related solely to the different approach employed for surface characterization. The influence of surface characterization approaches on the contact parameters and the resulting predictions is discussed in the contents of the presented results.



Author(s):  
John A. Trotter

Hemoglobin is the specific protein of red blood cells. Those cells in which hemoglobin synthesis is initiated are the earliest cells that can presently be considered to be committed to erythropoiesis. In order to identify such early cells electron microscopically, we have made use of the peroxidatic activity of hemoglobin by reacting the marrow of erythropoietically stimulated guinea pigs with diaminobenzidine (DAB). The reaction product appeared as a diffuse and amorphous electron opacity throughout the cytoplasm of reactive cells. The detection of small density increases of such a diffuse nature required an analytical method more sensitive and reliable than the visual examination of micrographs. A procedure was therefore devised for the evaluation of micrographs (negatives) with a densitometer (Weston Photographic Analyzer).



Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.



Planta Medica ◽  
2008 ◽  
Vol 74 (09) ◽  
Author(s):  
K Miyagi ◽  
T Fujise ◽  
N Koga ◽  
K Wada ◽  
M Yano ◽  
...  


Author(s):  
Jianqi Li ◽  
Yu Zhou ◽  
Jianying Li

This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.



The Synergist ◽  
2000 ◽  
Vol 11 (8) ◽  
pp. 26 ◽  
Author(s):  
Robert P. Streicher ◽  
Christopher M. Reh ◽  
Rosa Key-Schwartz ◽  
Paul C. Schlecht ◽  
Mary Ellen Cassinelli ◽  
...  
Keyword(s):  




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