ObjectiveTo study basic pattern of normal youth in gait analysis.Methods28 healthy young persons as experimental subjects were studied. The gait analysis system based on digital video and digital image processing was employed to obtain kinematic parameters.ResultsThe means and standard deviations of kinematic parameters of normal youth were obtained. The differences of gait patterns between males and females were compared. The correlations between gait parameters and height, weight were analyzed respectively.Conclusions It is recommended that the values of the gait parameters and the trends obtained can be used as a standard gait pattern of normal youth. Statistically significant differences exist between the males and the females for most of the gait parameters. Furthermore, the differences of the values of gait parameters between the males and the females are not led only by the difference of height except very few parameters.

Edge detection is an absolutely necessary step in medical image processing, and the use of differential operators to detect edge is one of the most common and effective methods. In this paper are analyzed the frequency features of the Roberts operator, Prewitt operator, Sobel operator and Laplacian operator from the viewpoint of frequency domain, and it is proposed that the frequency features of the differential operators should be considered when differential operator is being used and/or constructed. Because edge detection operator is sensitive to the edge type, the appropriate operator should be adopted in different edge type detection. Finally, the importance and necessity of selecting edge detection operator are validated in the MRI image edge processing.
Algorithms ; Brain ; pathology ; Humans ; Image Enhancement ; methods ; Image Interpretation, Computer-Assisted ; methods ; Image Processing, Computer-Assisted ; Magnetic Resonance Imaging ; Pattern Recognition, Automated ; methods

OBJECTIVETo study micro morphology and element-mixing distribution of different alloys welded in laser and analyze the feasibility of laser welding different alloys.

METHODSAlloys and titanium were matched into 4 groups: Au-Pt with Ni-Cr; Au-Pt with pure Ti; pure Ti with Ni-Cr; Ni-Cr with Co-Cr. They were welded in laser. Changes in metallography after hybridization of crystalline grain, ranges of heat-affected zone and pores were observed through SEM with ultra-thin windowed X-ray energy atlas. Meanwhile 10 testing points were chosen with area of 300 micro m x 900 micro m along the welding surface from the side A alloy to the side B alloy, than the element mixing distribution and tendency were analyzed with X-ray energy atlas.

RESULTS1. Hybridization of different alloys: (l) in the group of Au-Pt with Ti, there was titanium element mixing into Au-Pt tissue gradually and evenly on the Au-Pt side of the interface without clear boundary and increasing in size of crystalline grain. However, there was titanium crystalline grain increasing in size, irregular morphology and small sacks on the titanium side with clear boundary. (2) in the group of Ni-Cr with Ti, there was mixing regularly, slow transition and interlocks between crystalline grains on the Ni-Cr side of the in terface. Poor transition, clear boundary and small cracks were observed on titanium side. (3) in the group of Co-Cr with Ni-Cr, there was good transition, obscure boundary on both sides resulting from network, cylinder and branch structure growing. 2. Element-mixing distribution of different alloys. In fusion zone, the metal elements in matched groups mixed well and hybridized into new alloys except titanium blocks. The location of wave peak depended on the composition of alloys. Most of elements were from the alloy far from the fusion zone.

CONCLUSIONThe hybridization between pure titanium and any other alloys is not good The effect of laser welding different alloys is ideal except with pure titanium.

Alloys ; Chromium Alloys ; chemistry ; Dental Alloys ; chemistry ; Dental Soldering ; Titanium ; chemistry ; Welding