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991.
992.
使用Levenberg-Marquardt训练函数的神经网络算法在复合材料板上进行声发射定位,采用声波到达时间作为输入向量,训练得到了到达各个传感器的声波触发时间与板上坐标的良好的映射关系。考虑到波形衰减,用传统的固定门槛提取的到达时间容易与实际情况偏差较大,讨论了一种相对准确的适合工程使用的到达时间提取方法。 相似文献
993.
994.
Cheng Chang Lian-Fang Feng Xue-Ping Gu Cai-Liang Zhang Xi Chen Guo-Hua Hu 《American Institute of Chemical Engineers》2022,68(4):e17572
The molecular weight distribution (MWD) of polymers is a target of the optimization and control of industrial polymerization processes, as it dictates the processability and properties of polymers. A method, named as segment probability method, is developed to calculate the MWD of polycondensates produced by monomers of types A2 and B2 in a continuous reactor. It considers a growing chain as being composed of A and B segments in the middle of the chain and two terminal segments at the chain ends. It calculates the propagation probabilities of these different types of segments upon taking into account both the polycondensation and side reaction kinetics as well as the residence time distribution of the continuous reactor. The method is validated by poly(butylene terephthalate) (PBT) obtained from an industrial polymerization process composed of a continuous esterification reactor. The MWDs of the PBT calculated by this method are in agreement with those measured by size exclusion chromatography with mean square errors less than 10%. 相似文献
995.
Kaiyun Fu Sunyang Wang Zhenbin Gu Yushu Liu Tianming Zai Shijie Li Xianfu Chen Minghui Qiu Yiqun Fan 《American Institute of Chemical Engineers》2022,68(2):e17471
Membrane absorption (MA) has a great prospect for CO2 capture. In MA modeling, conventional one-dimensional (1D)- and two-dimensional (2D)-models make simplification of membrane contactor (MC) geometry. Geometry simplification allows an easy process modeling and numerical solution, however, is only reasonable for particular MCs. Here, efforts are underway to quantify the geometry effect on the MA-CO2 performance. First, we proposed a rigorous 3D model without geometry simplification for simulating the MA-CO2 process in real MCs and then validated it with experimental data. More importantly, we highlighted a preferable hybrid model in which two correction factors were introduced to a 2D model to make the simulation results approximately equal to the 3D simulation values. The correction factors were correlated with dimensionless fluid dynamic parameters for characterizing the geometry effects on flowing fluids. Such hybrid modeling contributes to characterizing the influence of geometry on the MA-CO2 performance and improving computation accuracy-efficiency combinations. 相似文献
996.
以环氧丙烯酸酯( G500-P)、三乙烯四胺( TETA)和烯丙基二甘醇二碳酸酯( CR-39)为反应体系,通过反应诱导相分离法制备了微米级环氧丙烯酸酯微球( EAMs)消光母液。改变反应体系中 G500-P的用量,可在较大范围内控制 EAMs的粒径。通过 UV固化的方法将复配的消光母液与透明 UV固化涂料制成光扩散膜,探究了 CR-39与 G500-P不同质量比时制得的消光母液以及母液添加量对光扩散膜光学性能的影响,并对光扩散膜的实际消光效果进行了分析。结果表明:当选用 CR-39与 G500-P质量比为 7∶3制得的消光母液,添加量为 10%时,光扩散膜的透过率达到 84. 2%,同时雾度高达 85. 4%,光扩散膜兼具高透过率与高雾度。与传统直接共混微球的方式相比,添加消光母液能有效解决微球在共混过程中团聚的问题。 相似文献
997.
Yinteng Shi Lin Ai Haonan Shi Xiaoyu Gu Yujun Han Jixiang Chen 《Frontiers of Chemical Science and Engineering》2022,16(4):443
Carbon-coated Ni, Co and Ni-Co alloy catalysts were prepared by the carbonization of the metal doped resorcinol-formaldehyde resins synthesized by the one-pot extended Stöber method. It was found that the introduction of Co remarkably reduced the carbon microsphere size. The metallic Ni, Co, and Ni-Co alloy particles (mainly 10–12 nm) were uniformly distributed in carbon microspheres. A charge transfer from Ni to Co appeared in the Ni-Co alloy. Compared with those of metallic Ni and Co, the d-band center of the Ni-Co alloy shifted away from and toward the Fermi level, respectively. In the in-situ aqueous phase hydrodeoxygenation of methyl palmitate with methanol as the hydrogen donor at 330 °C, the decarbonylation/decarboxylation pathway dominated on all catalysts. The Ni-Co@C catalysts gave higher activity than the Ni@C and Co@C catalysts, and the yields of n-pentadecane and n-C6–n-C16 reached 71.6% and 92.6%, respectively. The excellent performance of Ni-Co@C is attributed to the electronic interactions between Ni and Co and the small carbon microspheres. Due to the confinement effect of carbon, the metal particles showed high resistance to sintering under harsh hydrothermal conditions. Catalyst deactivation is due to the carbonaceous deposition, and the regeneration with CO2 recovered the catalyst reactivity. 相似文献
998.
根据舞钢300 mm厚板辊式淬火线工艺特点,结合以往采用淬火槽生产大厚度临氢Cr-Mo钢的经验及其性能要求,对钢板成分设计和正火加速冷却过程关键工艺参数进行研究,确定了大厚度临氢Cr-Mo钢板在舞钢300 mm厚板淬火线合适的正火加速冷却工艺,成功实现了大厚度临氢Cr-Mo钢板的批量生产.检验结果表明:由300 mm厚板辊式淬火线生产的大厚度临氢Cr-Mo钢板,力学性能稳定,完全满足严格的使用要求,同时板型控制效果良好,在国内临氢压力容器制造领域得到广泛应用. 相似文献
999.
Geometric error compensation for five-axis ball-end milling by considering machined surface textures
Guoqiang Fu Tengda Gu Hongli Gao Yu’an Jin Xiaolei Deng 《The International Journal of Advanced Manufacturing Technology》2018,99(5-8):1235-1248
Arbitrarily adjusting tool poses during error compensation may affect the quality of surface textures. This paper presents one tool center limitation-based geometric error compensation for five-axis ball-end milling to avoid the unexpected machined textures. Firstly, the mechanism of cutter location generation with cuter contact (CC) trajectory is analyzed. Due to zero bottom radius of ball-end cutter, CC points of the surface are only related to the tool center of the cutter. Realizing that, tool center limitation method of ball-end milling is established based on the generation of movements of all axes in order to ensure the machined textures. Then, geometric error compensation of ball-end milling is expressed as optimizing rotation angles of rotary axes by limiting tool centers of cutter locations. Next, particle swarm optimization (PSO) is intergraded into the geometric error compensation to obtain the compensated numerical control (NC) code. The limited region for particles of rotation angles is established, and moving criterion with a mutation operation is presented. With the help of the tool center limitation method, fitnesses of all particles are calculated with the integrated geometric error model. In this way, surface textures are considered and geometric errors of the machine tool are reduced. At last, cutting experiments on five-axis ball-end milling are carried out to testify the effectiveness of the proposed geometric error compensation. 相似文献
1000.
Effect of forces on dynamic metal transfer behavior of cable-type welding wire gas metal arc welding
Zhidong Yang Chenfu Fang Yong Chen Bin Liu Qingxian Hu Xiaoyan Gu 《The International Journal of Advanced Manufacturing Technology》2018,97(1-4):81-90
A cable-type welding wire (CWW) gas metal arc welding (GMAW) method was proposed as a novel approach, using CWW for the consumable electrode. Droplet transfer influences the welding process, and the forces on the droplet were analyzed to elucidate the metal transfer phenomenon observed during the welding process. The effects of the arc pressure, rotating force, and welding parameters were analyzed to understand the metal transfer. The special structure of the CWW affected the arc characteristics and forces during metal transfer as part of the welding process. The droplet formed by droplets from each thin wire, the arc, and electromagnetic forces on droplet formation and the coupling process were analyzed. The arc pressure and rotating forces are beneficial to metal transfer and increase the droplet transfer frequency. The droplet size decreases with increasing welding parameters. 相似文献