Papers by Keyword: Curvature

Abstract: In order to achieve fast and accurate face recognition, firstly, this paper extracts face contour lines based on face contour feature to achieve treat a human face shape classification, thereby reducing the measured face search range. Secondly, using the method of Gabor wavelet to extract local texture on face when range was approximately determined, then matching with the face library whose range has been narrowed. Experiments show that this parallel approach not only achieved rapid recognition, but also achieve a high recognition rate due to a combination of the two methods.

Abstract: In this study, the finite element software ANSYS was used to analyze the mechanical behavior of local sharp-notched circular tubes under cyclic bending. The local sharp-notched depths include: 0.2, 0.4, 0.6, 0.8 and 1.0 mm, and the local sharp-notched directions include: 0, 30, 60 and 90 degrees. According to the experimental result, the notch depth has no influence on the moment-curvature relationship. But the notch depth increases, the unsymmetrical phenomenon of the ovalization-curvature relationship becomes more obvious and the speed of ovalization accelerates. In addition, the ovalization-curvature relationship becomes symmetrical when the direction angle increases. The ANSYS analysis was compared with the experimental finding. Although some differences between the experimental and simulated results, but both trends were very similar.

Abstract: The 3D models obtained from laser radar are often used to analyze the objects’ reconstruction. Due to the target’s structure and the viewing angle, multi-angle scan are demanded to cover target’s whole surface, which means data got from different directions need to be spliced together. The ICP algorithm can register accurately. But if the surface of target is complex, such as aircrafts, the direct use of ICP algorithm is difficult to complete. In this paper, the corresponding points are found by the point features: normal vector, curvature and point feature histogram descriptor. The initial registration with rotation matrix and translation vector calculated from the corresponding points can be achieved. Then, improved ICP algorithm can be used to register accurately. This method is accurate and reliable with the test of aircrafts data.

Abstract: The main objective of the presented study and simulations conducted was to investigate the prospect of using B-spline curves for the automatic parking, i.e. self-driving, or intelligent vehicles. We consider the problem of parallel parking for a non-holonomic vehicle with a known maximum path curvature. The relationship between the properties of the path and the geometry of corresponding parking spot is revealed. The unique properties of B-splines are exploited to synthesize a path that is smooth and of continuous curvature. The contributions of this project are in the generations of better, smooth continuous paths. This improves passenger comfort during the parallel parking maneuver and allow vehicles to park in tighter spots by increasing the feasible range of the parking manoeuver.

Abstract: Laser peen forming, is a purely mechanical forming method achieved through the use of laser energy to form metal plate with small curvatures. Experiments were performed to investigate the effect of pre-bending on the plate bending deformation induced by laser peen forming. The pre-bending of plate was accomplished by a fixture with the cambered top surface. The pre-bending curvature radius is calculated and is used to design cambered surface. The LPF experiments are performed with Nd: YAG laser with overlapping laser spots. It is found that the convex deformation can be induced after laser shocks. And its curvature radius in the elastically elongated direction can be greatly increased by applying pre-bending, while in the perpendicular direction, the curvature radius is decreased.

Abstract: This paper focuses on the study of the curvatures of deflector installed on the below receiving device to effect the dust amount from the free falling particle stream. The deflector curvature was artificially controlled to limit the fugitive dust direction which was generated by the collision between the free falling bulk materials and the receiving device. This method was used to improve efficiency of the dust control system to exhaust fugitive dust, and to achieve the targets of energy conservation and emissions reduction. The experimental method was adopted to explore the relationship between the deflector curvature and the producing dust quantity. The experimental results indicated that, the dust suppression effect containing deflector contained a certain radian was more remarkable, when the height of the free falling of bulk materials was constant. The producing dust quantity decreased slightly with the deflector curvature increasing, and then increased rapidly. When the deflector curvature was 0.045 cm-1 or 0.060cm-1, the minimum of producing dust quantity could be obtained, and the dust removal effect might be significant.

Abstract: The roller straightening process is a common method for straightening long products like beams after rolling and cooling. This process often causes an adverse residual stress state. All previous investigations operate only with the roller adjustment as correcting variable. However, this cannot properly describe the consequences on the cross section of the beam during bending. The present paper presents a concept to consider the development of curvature during the straightening process. In finite element analyses using Abaqus/Standard a beam with a rectangular cross section and simplified material properties is modeled for a fundamental and clear demonstration. The theo-retically determined residual stress state depends on the development of curvature during straight-ening. Vice versa it is possible to design a trend of curvature with the goal of tailoring the final re-sidual stress distribution to the desired optimum. The necessary roller adjustment is found in a simulation using the Abaqus user subroutine UAMP, where the curvature is permanently tuned by controlling the roller adjustment. The residual stress state resulting from these 1D considerations (“the theoretical stress state”) is verified in a subsequent 2D analysis giving the “actual stress state”. A comparison of the theoretical and the actual residual stress state illustrates the influence of the roller contact. The concept presented in this work can be applied to complex cross sections in com-bination with realistic material properties. However, for this purpose a large amount of calculation resources due to an extensive 3D modeling are needed.

Abstract: Blood pressure is one of the most important indexes for human beings health. This paper presents an optimized algorithm to measure arterial blood pressure based on oscillometric technique. The bilateral filter and Gaussian-fitting method are respectively expressed to apply in noise eliminating, oscillation pulse extracting and curve fitting. The systolic pressure and diastolic pressure are determined by combination of proportional coefficient method, maximum slope method and curvature method. Moreover, a judgment for arrhythmias is employed in heart rate calculation. Experimental results have proved the precision and accuracy of the algorithm.

Abstract: A method for computing lines of curvature and umbilical points is proposed. These properties, derived for NURBS surfaces, are useful in shape modeling for both aesthetic and functional characteristics evaluation. Moreover, the application to the ship-hull design and to the progressive additional lens design, of umbilics and lines of curvature are investigated.

Abstract: Travelling wave thermoacoustic heat engines have been reported to have a higher efficiency than the standing wave ones. The former are generally large systems which consist of toroidal shape resonators. While standing wave heat engines are inherently smaller, a reduction in size could be considered which may involve curvatures as compared to the straight tube conventional systems. However, as with the streaming losses in the travelling wave resonators, losses due to the curvature may be generated. This study involves preliminary experimental measurements using the Particle Image Velocimetry (PIV) method to analyze the velocity profiles in a standing wave resonator before and after a ninety degree curvature. This design can reduce the space generally occupied by the straight standing wave resonator. The overall length of the resonator fits a quarter wavelength wave based on the straight closed-end tube type. The working gas is air at 1 atmospheric pressure. Results have shown that the velocity profiles after the stack but before the curvature exhibit clear straight paths up just as reported elsewhere. Signs of disordered motion could be observed just before the bend and the pattern continues until after the curvature. The results are obtained before one periodic cycle and before the acoustic wave front hit the tube end. The trend is expected to affect the overall thermoacoustic performance of the engine as returning gas particles interact with the oncoming particles that pass by the curvature.