Tang Yiping

Image Matching for Geomorphic Measurement Based on SIFT and RANSAC Methods

To effectively realize the image feature matching for geomorphic reverse measurement and rebuilding, a new matching scheme is presented, where the SIFT method are adopted to implement initial geomorphic image matching by going through five stages: scale-space construction, scale-space extrema detection, orientation assignment, keypoint descriptor and feature vector matching. Then, in order to eliminate the wrong matching features existing in the initial matching process, RANSAC algorithm is applied. The experimental results show that this algorithm can effectively improve the accuracy and efficiency of geomorphic image matching.

Nano‐TiO2‐modified photosensitive resin for RP

Purpose – The purpose of this paper is to improve the mechanical and thermal properties of photosensitive resin for rapid prototyping (RP) by modifying with nano‐TiO2.Design/methodology/approach – The silane coupling agent was selected to treat the surface of anatase nano‐TiO2 particles. The IR spectrum showed that the hydroxyl (−OH) group on the surface of nano‐TiO2 reacted with the coupling agent effectively. The effects of TiO2 content on the curing depth and viscosity of the photosensitive resin were studied by experiments. The mechanical properties including tensile strength, tensile modulus, flexural strength and hardness were tested according to ASTM standards. The thermal stability of modified photosensitive resin was tested by differential scanning calorimetry.Findings – The comprehensive performance of the modified photosensitive resin was good when TiO2 content was at 0.25 per cent, the tensile strength was increased by 89 per cent from 25.26  to 47.82 MPa, the tensile modulus increased by 18 p...

A Cutter Layout Optimization Method for Full-Face Rock Tunnel Boring Machine

A cutter layout optimization strategy for full-face rock tunnel boring machine(TBM)is proposed,to overcome the difficulty that the original design proposal usually can not meet the balance challenge of cutter head forces as well as the rock breaking amount of each cutter.In the strategy the position radius and position angle are solved separately.The layout scheme sets are established by grouping the cutters and exerting micro-adjustment for the position angle and radius,considering the requirements of design proposal,number of scheme sets and the computing rate.The best layout pattern is achieved by selecting the layout scheme following weighted grey target way.The TB880E TBM cutter layout proposal are optimized,compared with the computational results of the original layout design,the eccentric moment decreases by 65%.Since the cutter layout pattern are not adjusted,the optimization strategy enables to avoid stress concentration in some degree without harm to structural stiffness.A cutter layout optimization strategy for full-face rock tunnel boring machine (TBM) is proposed, to overcome the drawback that the original design usually can not meet the balance requirements for cutter head forces and the rock breaking amount of each cutter. The layout schemes are designed by grouping the cutters and exerting micro-adjustment for the position angle and radius. The best layout is achieved by selecting the layout schemes using grey relational analysis and the TB880E TBM cutter layout are optimized. Compared with the computational results of the original layout design, the eccentric moment decreases by 65%. It is concluded that the position angle plays a main role in cutter layout optimization, and the cutter layout exerts obvious influence on cutter head performance. The optimization strategy can avoid stress concentration without doing harm to structural stiffness.

An Image Matching Method on Photography Measurement

The image feature matching is a critical step in photography measurement and rebuilding. Based on the Characteristics of topography measurement, a new topography feature matching algorithm is presented in this paper. In the algorithm, the stereo images to be matched are partitioned, and then the region matching process is used to these partitioned image pairs. Based on the region matching, the corner feature matching operation is then processed, which involves relaxed iteration algorithm, zero-crossing method and least squares median algorithms to eliminate the ill matching points. Three groups of topography photography measurement images are used in image matching experiment, the experiment results shows that this algorithm can effectively improve the computation efficiency and matching accuracy, thus has a wide applications in the area based on the principle of stereo vision, such as: topography photography measurement, urban planning, etc.

Visualization of resist flow fields in microlithography by using defocusing digital particle image velocimetry

Abstract. The resist filling behavior is crucial to the quality of the final imprinted pattern in micro/nanolithography. To obtain resist flow fields, a three-dimensional (3-D) defocusing digital particle image velocimetry (DDPIV) system was set up to realize the visualization of the resist filling process. Three-dimensional motion trajectories and velocity vectors of tracer particle sets were calculated to characterize this microscale flow phenomena. The results show that the particles’ maximum velocity is located in the region below the mold corner, and the region leans to the mold cavity. Meanwhile, the squeezed resist will first move along the mold moving direction, and then fills the mold cavity in an upward moving tendency when it passes through the mold corner. The feasibility of using the DDPIV system to investigate the resist filling behavior was confirmed. The results will help to understand the resist filling behavior and provide useful instruction for the selection of process parameters and mold structure optimization.

A new slicing method of reverse engineering based on the principle of refraction and reflection

The traditional slicing method of reverse engineering has been used in product measure from time immemorial. This method however has the disadvantage of low contrast of the cross-sectional pictures of an object. In order to overcome the said shortcoming, a new slicing method of reverse engineering, based on the principle of refraction and reflection of a prism, has been propounded. According to the reflectivity of the object, one of the illuminating methods—straight illuminating or inclined illuminating—is adopted. These methods can enable one to obtain the image of the cross-section of a bright object with a dark background or the opposite. Experiments have proved to show the advantages of this new slicing method for high contrast of the cross-sectional pictures. To eliminate geometrical distortions caused by the refraction and reflection of the prism, a mathematical transformation model can be set up to correct the image by using relevant software. Eventually, a RP model of a temporomandibular joint fabricated according to its slicing pictures is illustrated.