查看更多>>摘要：Laser assisted machining (LAM) is an effective method machining difficult-to-machine materials such as ceramics which uses a high power laser to focally heat a workpiece prior to material removal with a traditional cutting tool. A laser assisted machining experiment system was set up and a transient, three-dimensional heat transfer model was developed for LAM of silicon nitride using Finite Element Method to understand the thermal process of laser heating. The model was based on temperature-dependent thermophysical properties and the heat generated was neglected due to cutting which is assumed to be small compared to the heat generated by laser heating. The experiments were carried out to investigate the effects of operating parameters, such as laser power, laser translational speed, rotational speed, laser beam diameter and preheating time on temperature distribution. An infrared radiation thermometer was used to measure the surface temperature histories and the experimental results were in good agreement with predictions. The laser power and laser translational speed have the greatest influence on the temperature.
查看更多>>摘要：Diatomite-altapulgite composite nano-size adsorbent was prepared using natural diatomite and attapulgite through compounding, granulation, calcination and activation. After elementary characterization of this adsorbent by mercury porosimeter, batch tests were carried out to examine its removal mechanism of brilliant green. The influence of adsorbent concentration, contact time, pH, temperature and initial brilliant green concentration on the dye removal were investigated. Increase in adsorbent dosage led to increase in brilliant green adsorption due to increased number of adsorption sites. Maximum adsorption of brilliant green was found at adsorbent dosage of 100 g/L. Adsorption equilibrium attained within 2 h time. The pH variation studies showed that the adsorption process was highly pH dependent. The optimum pH for adsorption of brilliant green was found to be >7. The sorption of brilliant green decreased with the rise of temperature because adsorption process was exothermic. Adsorption isotherm studies showed that Langmuir model fitted the experimental data better than Freundlich model.
查看更多>>摘要：The advanced manufacturing technology of TiNiNb wide hysteresis shape memory alloy fastener ring was performed by using the tungsten inert gas (TIG) welding technique. It was found that transformation temperatures of the joint were about 20 ℃ higher than these of the base alloy, which should be ascribed to the heat treatment in the joint caused by welding. The strain recovery behavior of the ring after the diameter expanding process was studied. For the ring with the diameter expansion of 16% and without the heat treatment after welding, the strain recovery began at 55℃ and ended at 75℃. It is concluded that, by appropriate expanding diameter process. TIG welding technique is suitable for the production of TiNiNb wide hysteresis shape memory fastener ring.
查看更多>>摘要：By means of Friction stir welding (FSW), as-cast AM50 magnesium alloys were welded with travel speed of 50 mm/min and rotating rate of 1200 r/min. The thermal cycle was investigated by thermocouples and a paperless recorder. The results show that phenomenon of dual peaks and hysteresis exist in temperature curves of featured points at the starting part while only hysteresis in the middle part. The finishing part has the highest peak temperature while the starting part corresponds to the lowest one. Featured points for different depths in the same place share the same shape of temperature curves but with different peak temperature. The retaining time over recrystallization temperature at middle part is double that at finishing part.
查看更多>>摘要：In this paper, the TaCx coating with thickness around 1.2 μm was prepared by radio frequency magnetron sputtering technique on the 316L stainless steel substrate to improve its hemocompatibility. The structure and morphology of the coating were characterized by XRD and SEM. The XRD results indicated that TaCx, as a new species, appeared on the surface of the 316L stainless steel substrate. SEM images showed that the surface morphology of the TaCx coating was uniform and dense. The mechanical characteristics of the coating were measured by nanoindentation, giving a nanohardness of 13 GPa and a Young's modulus of 210 GPa. The adhesion strength of the TaCx coating to 316L stainless steel depended on the sputtering bias voltages and increased for a higher bias voltage. The hemocompatibility of the TaCx coating, as evaluated by platelet adhesion tests, was compared to that of the bare 316L stainless steel. The results indicated that the hemocompatibility of 316L stainless steel with TaCx coating was significantly improved as compared to the original one.
查看更多>>摘要：Silica gel was modified with polymerizable double bonds on the surface. Then the molecular imprinting polymer imprinted with D-Phenylalanin was grafted on the surface of modified silica gel. The molecularly imprinted polymer (MIP) based on the surface of silica gel was characterized by IR and scanning electron microscopy (SEM). The adsorption property of D-Phenylalanin by MIP was mearsured. The MIP with the combined functional monomers exhibited better adsorption properties and selectivity compared with the corresponding non-imprinted polymers or MIP with the single functional monomer. The material could be used in separation research field, such as packing material of high performance liquid chromatography, solid-phase extraction and so on.
查看更多>>摘要：Diamond wire saw was a tool which is used to cut the steel-based material, its grinding mechanism was researched in the paper. Based on technical characteristic of the diamond wire, a string of diamond beads in the cutting moment was detected by using the electron microscope. Wear figuration and invalidation reason of the diamond beads was analyzed, and mathematic relation among wear rate, feed velocity and cutting velocity of the diamond wire were educed, and reasonable cutting parameters were received. In order to validate the mathematic model, the experiment was finished. When the diamomd wire saw is used to cut the steel-based material, its two experiential formulas of radial feed force and tangent cutting force are educed by using the orthogonal regression method. In the formula, radial force and cutting force is increasing with augment of the workpiece breadth, ridial feed velocity and cutting velocity, and influence of the workpiece breadth to the cutting force is more than to the radial force. Meanwhile, experiment show yet that error between theory cutting(or feed) force and actual cutting(or feed) force is in the reasonable scope.
查看更多>>摘要：The orthogonal theories were carried out to analyze the effect of MDI, UF and FRW content on the mechanical and fire retardant properties of rice-straw hased boards in this paper. The interface alkaline treatment showed a significant effect on the surface bonding performance of rice-straw. The bonding property of rice-straw based boards increased with the increasing of resin content, especially for the effect of MDI content on MOR, MOE. The tendency of pkHRR decreased and the target for fire retardant realized by the FRW content increased. Based on analysis, the optimal technical parameters were obtained as MDI content 3%, UF content 6% and FRW fire retardant 10% separately.
查看更多>>摘要：In the paper, the knowledge-based architecture for product design with modules is suggested, which discovers and shares the product knowledge and design rules to increase the effectiveness/efficiency of the product design with modules. This solution approach involves modeling modular products knowledge, modular components selection, and feasible sequence of assembly. In modular products knowledge model, an object-oriented approach is introduced to capture the knowledge of modular product. In modules selection and feasible sequence of assembly, a reasoning mechanism is fabricated based on Protegee and JESS expert tool. Last, a particular case of bicycle design is studied through the use of this knowledge-based prototype system to prove the effectiveness/efficiency of product design with modules. However, a knowledge-based system of product design with modules is also implemented to provide adaptive design rules and share design knowledge in distributed environment. It will greatly enhance the competitive capability of companies trying to reduce the engineering design change.
查看更多>>摘要：Shortest path is the core issue in application of WebGIS. Improving the efficiency of the algorithm is an urgent requirement to be resolved at present. By the lossy algorithm analyzing, which is the current research focus of the shortest path algorithm to optimize, utilizing adjacency table of storage structures, restricted direction strategy and binary heap technology to optimize the algorithm, thereby reduce the scale of algorithm to improve the operating efficiency of algorithm. This scheme has been applied in the simulation of the data downloaded from the Guangdong Provincial Highway Network Information System and satisfactory results have been obtained.
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