A Single Image 3D Reconstruction Method Based on a Novel Monocular Vision System

Three-dimensional (3D) reconstruction and measurement are popular techniques in precision manufacturing processes. In this manuscript, a single image 3D reconstruction method is proposed based on a novel monocular vision system, which includes a three-level charge coupled device (3-CCD) camera and a ring structured multi-color light emitting diode (LED) illumination. Firstly, a procedure for the calibration of the illumination’s parameters, including LEDs’ mounted angles, distribution density and incident angles, is proposed. Secondly, the incident light information, the color distribution information and gray level information are extracted from the acquired image, and the 3D reconstruction model is built based on the camera imaging model. Thirdly, the surface height information of the detected object within the field of view is computed based on the built model. The proposed method aims at solving the uncertainty and the slow convergence issues arising in 3D surface topography reconstruction using current shape-from-shading (SFS) methods. Three-dimensional reconstruction experimental tests are carried out on convex, concave, angular surfaces and on a mobile subscriber identification module (SIM) card slot, showing relative errors less than 3.6%, respectively. Advantages of the proposed method include a reduced time for 3D surface reconstruction compared to other methods, demonstrating good suitability of the proposed method in reconstructing surface 3D morphology

Topology Optimization of Spatially Compliant Mechanisms with an Isomorphic Matrix of a 3-UPC Type Parallel Prototype Manipulator

A novel topology optimization approach is proposed in this paper for the design of three rotational degree-of-freedom (DOF) spatially compliant mechanisms, combining the Jacobian isomorphic mapping matrix with the solid isotropic material with penalization (SIMP) topological method. In this approach, the isomorphic Jacobian matrix of a 3-UPC (U: universal joint, P: prismatic joint, C: cylindrical joint) type parallel prototype manipulator is formulated. Subsequently, the orthogonal triangular decomposition and differential kinematic method is applied to uncouple the Jacobian matrix to construct a constraint for topology optimization. Firstly, with respect to the 3-UPC type parallel prototype manipulator, the Jacobian matrix is derived to map the inputs and outputs to be used for initializing the topology optimization process. Secondly, the orthogonal triangular decomposition with the differential kinematic method is used to reconstruct the uncoupled mapping matrix to derive the 3-UPC type parallel prototype manipulator. Finally, a combination of the solid isotropic material with penalization (SIMP) method and the isomorphic mapping matrix is applied to construct the topological model. A typical three rotational DOF spatially compliant mechanism is reported as a numerical example to demonstrate the effectiveness of the proposed method

Molybdenum and Tungsten nitrosyl complexes in hydrogen activation

Two transition-metal hydride complexes of the type M(dippe)(2)(NO)(H)] M = W (2a), Mo (2b); dippe = 1,2-bis(di-isopropylphosphanyl)ethane] have been prepared by the reaction of M(dippe)(2)(NO)(Cl)] M = W (1a), Mo (1b)] with LiBH4. The nitrosyl groups of the tungsten complexes la and 2a are capable to coordinate a LiBH4 molecule to form the stable adducts W(dippe)(2)(Cl)(NO center dot center dot center dot LiBH4) (1c) and W(dippe)(2)-(H)(NO center dot center dot center dot LiBH4) (2c). Addition of ethylenediamine to a toluene solution of 2c led to rupture of the 2c adduct and afforded 2a in good yield. After the interaction of 2a with H(Et2O)]BF4], the stable seven-coordinated cationic dihydride W(dippe)(H)(2)(dippe)(NO)]BF4] (6a) was isolated. The reaction between 2b and H(Et2O)]BF4] led to the formation of Mo(dippe)(2)(NO)(FBF3)] (6b) in which BF4- was found to be coordinated to the metal centre. The H(Et2O)(2)]BAr4F] Ar-F = 3,5-(CF3)(2)C6H3] acid interacted with 2a to yield the seven-coordinated complex W(dippe)(H)(2)(dippe)(NO)]-BAr4F] (5a) similar to 6a. In the reaction between 2b and H(Et2O)(2)]BAr4F], the 16e(-) five-coordinated complex Mo-(dippe)(2)(NO)]BAr4F] (4b) was formed. X-ray diffraction revealed that 4a has a weak agostic interaction trans to the NO ligand. Complex 4b was found to react rapidly with hydrogen gas under ambient conditions to form the dihydride complex Mo(dippe)(H)(2)(dippe)(NO)]BAr4F] (5b), which is unstable in the absence of a hydrogen atmosphere. The equilibrium constant for the reversible reaction of 4b with hydrogen was found to be K = 2.6 bar(-1) at 25 degrees C. Complex 4b was tested as a catalyst for acetone hydrogenation; a maximum TON of 7 was found