Search Results

You are looking at 1 - 10 of 61 items

  • Author: Lei Shi x
Clear All Modify Search

Abstract

In this paper, an object recognition method and a pose estimation approach using stereo vision is presented. The proposed approach was used for position based visual servoing of a 6 DoF manipulator. The object detection and recognition method was designed with the purpose of increasing robustness. A RGB color-based object descriptor and an online correction method is proposed for object detection and recognition. Pose was estimated by using the depth information derived from stereo vision camera and an SVD based method. Transformation between the desired pose and object pose was calculated and later used for position based visual servoing. Experiments were carried out to verify the proposed approach for object recognition. The stereo camera was also tested to see whether the depth accuracy is adequate. The proposed object recognition method is invariant to scale, orientation and lighting condition which increases the level of robustness. The accuracy of stereo vision camera can reach 1 mm. The accuracy is adequate for tasks such as grasping and manipulation.

Abstract

The semiconductor material Cobalt oxide (Co3O4) was selected for the experiment of artificial photosynthesis, but from sunlight capture to water splitting, the conversion efficiency of the whole process was below 10%. Doping is one of the methods to improve the conversion efficiency. In this paper we will calculate the conversion efficiency of exponential-doped Co3O4 film with different thickness. By solving continuity equation and compare the efficiency curves to find the best thickness, which can achieve highest conversion efficiency. Due to the regular pattern of exponential-doping is along the trend of the exponential function from one surface of the semiconductor layer to another. So, we can compare and find which surface under the illumination will show higher conversion efficiency and find the best film thickness. According to the result, the surface with lower doping concentration under the sunlight irradiate can get higher efficiency and the 4.4μm thickness layer show highest efficiency.

The development of a new strategy to immobilize the homogeneous chiral catalysts for enantioselective reactions is highly desirable in order to overcome some drawbacks of conventional approaches. In this lecture, a conceptually new strategy for heterogenization of homogeneous chiral catalysts (i.e., "self-supporting" approach) is presented. The concept focuses on the use of homochiral metal-organic coordination polymers generated by self-assembly of chiral multitopic ligands with metal ions as the heterogeneous catalysts, and thus obviating the need of any exogenous support. The application of this "self-supporting" strategy has been exemplified in heterogeneous catalysis of asymmetric carbonyl-ene, sulfoxidation, and epoxidation, as well as asymmetric hydrogenation reactions.

Abstract

Within effective field theory (EFT), the critical properties of a random transverse crystal field Ising model with bond dilution are studied on a square lattice. Under both weak and strong bond dilution conditions, we consider three cases (α = 0,±0.5) of a transverse crystal field ratio, obtaining global phase diagrams in T−D x space for changes in the random transverse crystal field concentration. The phase diagrams obtained for a weak bond dilution are very similar in shape to those of pure bond but with decreases in corresponding ordered phases and critical values. However, the phase diagrams for a strong bond dilution exhibit varieties, including a change in reentrant phenomenon, the occurrence of transverse crystal field degeneration, and the opposite direction crossover of temperature peak value.

Abstract

Electrical capacitance tomography (ECT) is considered to be a competitive measurement method. The imaging objects in ECT measurements are often in a time-varying process, and exploiting the prior information related to the dynamic nature is important for reconstructing high-quality images. Different from existing reconstruction models, in this paper a new model that incorporates the spatial correlation of the pixels by introducing the radial basis function (RBF) method, the dynamic behaviors of a timevarying imaging object, and the ECT measurement information is proposed to formulate the dynamic imaging problem. An objective functional that exploits the spatial correlation of the pixels, the combinational regularizer of the first-order total variation (FOTV) and the second-order total variation (SOTV), the multi-scale regularization, the spatial constraint, and the temporal correlation is proposed to convert the ECT imaging task into an optimization problem. A split Bregman iteration (SBI) method based iteration scheme is developed for solving the proposed objective functional. Numerical simulation results validate the superiority of the proposed reconstruction method on the improvement of the imaging quality.