科创中国

As the popularization of dual ring fieldbus,the optimized dual ring synchronization methods are still in short.The current synchronization methods are generally established in traditional industrial fieldbus,in which transmission is commonly considered in single track,the two-way transmitting cannot take full effect,and would result in unwanted idle load on equipment lines.In stamp-transferring part,the synchronizing algorithm is not properly processed to diminish the latency,so the real-time performance of entire system cannot be ensured.To support the synchronization control of stations in the CNC system,a real-time time synchronization method for dual ring fieldbus in the CNC system is designed in this paper.In this method a synchronizing message transmission scheme based on dual ring architecture and the synchronization algorithm between master and secondary stations are integrated.In the scheme,the clock models of both master and secondary stations are optimized with corresponding modules and the stamp data transmission based on the dual ring fieldbus is devised exclusively,so the transmitting efficiency improves with less idle work.In the algorithm,all the secondary stations can accomplish the consistent state with master station by updating clock discrepancy information in one communication cycle,and it takes the advantage of two-way transmitting and makes the best use of dual ring structure,so the real-time performance of the system can be promoted while retaining the precision of synchronization.To evaluate the performance,the costs of the method and errors during synchronizing are noted and analyzed based on the actual running environment in the industrial fieldbus.The results show that it reduces communication cost and ensures the smoothness of the system with low lag effects under heavy load.The proposed time synchronization method optimizes the architecture of sync message transmission in dual ring fieldbus,and improves the efficiency of time synchronization in the stations of CNC system.

Bearing ring is the crucial component of bearing. With regard to such problems as material waste, low efficiency and high energy consumption in current process of producing large bearing ring, a new process named "casting-rolling compound forming technology" is researched by taking the typical 42CrMo slew bearing as object. Through theoretical analysis, the design criteria of the main casting-rolling forming parameters are put forward at first. Then the constitutive relationship model of as-cast 42CrMo steel and its mathematical model of dynamic recrystallization are obtained according to the results of the hot compression experiment. By a coupled thermal-mechanical finite element model for radial-axial rolling of bearing ring, the fraction of dynamic recrystallization is calculated and recrystallized grains size are predicated. Meanwhile, the effects of the initial rolling temperature and feed rate of idle roll on material microstructure evolution are analyzed. Finally, the industrial rolling experiment is designed and performed, based on the simulation results. In addition, mechanical and metallographic tests are conducted on rolled bearing ring to get the mechanical parameters and metallographic structure. The experimental data and results show that the mechanical properties of bearing ring produced by casting-rolling compound forming technology are up to industrial standard, and a qualified bearing ring can be successfully formed by employing this new technology. Through the study, a process of forming large bearing ring directly by using casting ring blank is obtained, which could provide an effective theoretical guidance for manufacturing large ring parts. It also has an edge in saving material, lowering energy and improving efficiency.

介绍了机械式紧密纺的作用原理,对比了机械式、负压式紧密纺的优缺点.叙述了机械式紧密纺在上海-企业中的应用实例,对老机进行机械式紧密纺改造投资少、见效快,有节能和环保优势,具有推广潜力.

Dual mechanical port machine(DMPM), as a novel electromechanical energy conversion device, has attracted widespread attention. DMPM with spoke type permanent magnet arrangements(STPM-DMPM), which is one of several types of DMPM, has been of interest recently. The unique coupling characteristics of STPM-DMPM are beneficial to improving system performance, but these same characteristics increase the difficulties of control. Now there has been little research about the control of STPM-DMPM, and this has hindered its practical application. Based on a mathematical model of STPM-DMPM, the coupling characteristics and the merits and demerits of such devices are analyzed as applied to a hybrid system. The control strategies for improving the disadvantages and for utilizing the advantage of coupling are researched. In order to weaken the interaction effect of torque outputs in the inner motor and the outer motor that results from coupling in STPM-DMPM, a decoupling control method based on equivalent current control is proposed, and independent torque control for the inner motor and outer motor is achieved. In order to solve address the problem of adequately utilization of coupling, minimizing the overall copper loss of the inner motor and the outer motor of STPM-DMPM is taken as the optimization objective for optimal control, and the purpose of utilizing the coupling adequately and reasonably is achieved. The verification tests of the proposed decoupling control and optimal control strategies are carried out on a prototype STPM-DMPM, and the experimental results show that the interaction effect of torque outputs in the inner motor and the outer motor can be markedly weakened through use of the control method. The overall copper loss of the inner motor and the outer motor can be markedly reduced through use of the optimal control method, while the power output remains unchanged. A breakthrough in the control problem of STPM-DMPM is accomplished by combining the control methods. Good performance in the control of STPM-DMPM will enhance its practicality, particularly as applied to hybrid systems.

Due to the insufficiency of utilizing knowledge to guide the complex optimal searching, existing genetic algorithms fail to effectively solve excavator boom structural optimization problem. To improve the optimization efficiency and quality, a new knowledge-based real-coded genetic algorithm is proposed. A dual evolution mechanism combining knowledge evolution with genetic algorithm is established to extract, handle and utilize the shallow and deep implicit constraint knowledge to guide the optimal searching of genetic algorithm circularly. Based on this dual evolution mechanism, knowledge evolution and population evolution can be connected by knowledge influence operators to improve the configurability of knowledge and genetic operators. Then, the new knowledge-based selection operator, crossover operator and mutation operator are proposed to integrate the optimal process knowledge and domain culture to guide the excavator boom structural optimization. Eight kinds of testing algorithms, which include different genetic operators, are taken as examples to solve the structural optimization of a medium-sized excavator boom. By comparing the results of optimization, it is shown that the algorithm including all the new knowledge-based genetic operators can more remarkably improve the evolutionary rate and searching ability than other testing algorithms, which demonstrates the effectiveness of knowledge for guiding optimal searching. The proposed knowledge-based genetic algorithm by combining multi-level knowledge evolution with numerical optimization provides a new effective method for solving the complex engineering optimization problem.

目的 应用二维应变技术(2 DS)分析双腔起搏器置入前、后左室局部心肌的应变特点.方法 应用二维应变软件测量33例置入双腔起搏器患者术前、后的心尖四腔长轴左室壁各个节段的心肌纵向收缩期峰值应变(S)与应变率(SR).结果 与术前比较,双腔起搏器患者术后的后间隔中间段及心尖段、侧壁中间段及心尖段的心肌纵向收缩期峰值应变(S)与应变率(SR)均明显升高,差异均具有统计学意义(P均<0.05);其余左室壁节段置入双腔起搏器前、后的应变(S)与应变率(SR)差异均无统计学意义(P均>0.05).结论 置入双腔起搏器后,左室壁各节段心肌纵向运动的形变能力是不完全一致的.