Advanced Materials Research Vols. 457-458

Abstract: RF-MEMS resonator can meet the development of communication and attract great attention now. Applied to electric system, mechanical resonator caused some difficulties to the circuit design， the electric parameters should be extracted. Through mechanical-electrical analogy the electronic parameter is extracted and the electrical equivalent circuit established. ANSYS is used to simulate the vibration of the disk. Using the electronic parameters, an oscillator is designed and simulated.

Abstract: HfC-based precursors with a range of carbon/metal oxide ratios were prepared from polymerization and copolymerization of metal containing monomers during solution-based synthesis. Heat treatments were given to the precursors to produce HfC powders. FTIR was used to record the infra-red spectra of the preceramic powders. HfC powders were assessed using X-ray diffraction and scanning electron microscopy.

Abstract: For the flexible roll forming of the control system, this paper introduces a method that machine vision bind to the flexible roll forming control system. The detection method for sheet metal forming is image acquisition, image processing and other means for the extraction of sheet metal forming in some time section contour curve. Compare extraction section contour curve with the moment theory section contour curve in the control system, get the deviation value and feedback to the control system that interpolation arithmetic to realize closed loop control.

Abstract: A new kind of acoustic imaging technique was discussed in this article. The basic theory of acoustic imaging was stated and some result of simulation including the images of point source and plane wave in the imaging system was shown. The result of simulation of point source and plane wave prove that it is feasible in certain range of acoustic imaging. In high frequent band, we can get a obvious contrast between source and background and high resolution.

Abstract: Trip steel is broadly used in automobile manufacturing with its high strength and enhanced formability. For the variable section parts with protrusion and hole, roll forming is a kind of feasible way to realize continuous parts manufacturing, In the paper, with deep understanding of roll forming process and reasonable simplification, the FEM model of a multi-step variable section roll forming of 600MPa trip steel parts with protrusion and hole is established to analyze the mechanics and the deformation characteristics of the forming procedure. Equivalent stress, equivalent strain, sheet thickness and springback amount are extracted from the simulation result and studied comparatively, which is of great importance to understand the appearance of the forming defects. In addition, the forming load and torque of the rollers can also be obtained to guide the design of the variable section roll forming product line.

Abstract: How to manufacture high accuracy, complex section, high strength steel products is the current challenge of flexible roll forming technology. This article introduced opening NC system application in flexible roll forming, both in software and in hardware. As the core module of the software system, the interpolation module was discussed. The article mainly focused on how to establish track simulation module. According to the algorithm, we calculated the roller displacement and rotation angle using VC++. At last the simulation processes and results were presented, which prove the trace interpolation algorithm is correct and feasible.

Abstract: The goal of the present study was to investigate the degradation of hydroxyethyl chitosan-g-poly(D,L-lactide) (HECS-g-PDLLA) copolymers in vitro. For this purpose, HECS-g-PDLLA copolymers were firstly synthesized by bulk ring-opening polymerization with different n_D,L-lactide:n_{aminoglucoside} feed ratio. Then, a series of poly(D,L-lactide), chitosan and HECS-g-PDLLA copolymers films were prepared by solution casting method, and their degradation were carried out in vitro in saline water at 37 °C. The degradation properties were investigated by measurement of pH value, weight loss, and changes in the composition and structure of the HECS-g-PDLLA copolymers films with time. Results showed that the degradation of the HECS-g-PDLLA copolymers occurred firstly on the poly(D,L-lactide) side chains. The degradation rate of the graft copolymers obviously faster than that of CS, and can be controlled by changing the value of n_D,L-lactide:n_{aminoglucoside}. Due to the alkalinity of CS, the pH value of saline water for HECS-g-PDLLA copolymers degradation higher than that of PDLLA.

Abstract: A series of Ni-Ru bimetallic catalysts over La₂O₂CO₃ are prepared by an impregnation method. The catalytic properties are evaluated in ethanol steam reforming reaction from 350 to 700 °C under atmospheric pressure. Ni-Ru/La₂O₂CO₃ containing 6 wt% Ni and 3 wt% Ru is found to be more efficient, and Ni-La composite oxide could be formed in the catalyst. Ru is more active in the ethanol dehydration reaction to form ethylene than Ni. The presence of Ru could improve the selectivity for hydrogen of Ni catalyst. TG results reveal that Ni-Ru/La₂O₂CO₃ has excellent resistance to carbon deposition.

Abstract: Research was done on durability of two common kinds of carbon fiber reinforced polymer (CFRP) sheets. Eight groups of 40 sheets were tested in recent 3 years. Influence to strength, extensibility and modulus of CFRP sheets was investigated in nature aging environment of east China. Results indicate that strength、young’s modulus and extensibility of CFRP sheets deteriorated owing to climatic factors. An average value of aging residual strength semi-experienced math model is used to study time-dependent deterioration on fiber reinforced polymer affected by climatic factors of east China. Nonlinear fit parameter is used in retain rate curve equation to predict service life of CFRP. Further research is still going on.

Abstract: It’s common to see the dispute caused by pile driving construction vibration effect, which has become a concern of social problems. The paper analyzes the mechanism and law of ground vibration caused by the pile driving construction. Combined with the engineering practice, discussion about the defects in the criteria of vibration detection is presented. It is necessary to do assessment study on impact of pile driving vibration on surrounding houses. Project practice indicates that application of assessment study on impact of pile driving vibration on surrounding houses is an effective management.