先进制造技术的核心技术

产品设计思想创新和设计技术创新是先进制造技术的核心。在研究先进制造技术的体系和特点的基础地先进制造技术的设计思想和设计技术的主要内容。     

应用先进制造技术推进企业发展

先进制造技术是制造业赖以生存和发展的技术支撑,是高技术走向实际应用的接口、桥梁和通道,是提高企业国际竞争力的根本要素。企业只有应用先进制造技术才能适应新形势需要,才能进一步发展。     

先进制造系统适度递阶的协同控制的理论研究

随着全球化生产的形成,竞争的压力越来越大,制造企业也从传统的大批量生产转向单件、小批量的生产,用户需求多样化,个性化,这使得企业变得越来越复杂。传统企业采用的递阶式控制结构已无法对多变的市场环境作出响应,而现在比较流行的分布式结构由于技术条件的限制,还存在许多不足。本文提出了一种适度递阶的协同控制方法,它综合了递阶式和分布式控制的优点,因而具有更强的生命力。同时还给出了相应的控制基本结构和控制机理。     

Linear Analysis of Thermo-hydraulic Instabilities of the Advanced Heavy Water Reactor (AHWR)

Analysis was carried out to predict the threshold of instability for Ledinegg type and density wave oscillations for the Indian Advanced Heavy Water Reactor (AHWR) which is a Natural Circulation Pressure Tube Type Boiling Water Reactor. The mathematical model considers homogeneous two-phase flow and the conservation equations are solved analytically to obtain the steady state thermo-hydraulic characteristics and flow stability map. The model was applied for the AHWR concept after it had been validated with the test data obtained from a simple forced circulation loop with small parallel boiling channels and from the High Temperature Loop (PNC). The results indicate that the proposed design configuration of the AHWR may experience both Ledinegg type (static instability) and Type-I and Type-II density wave oscillations depending on the operating condition. The effects of various geometric and operating parameters on these types of instabilities were studied. It can be seen from the results that the Ledinegg type instability is suppressed with an increase in pressure and disappears when the operating pressure is higher than 0.7MPa. But the density wave instability may occur even at 7 MPa. In addition, it is found that for parallel multiple channels operating under natural circulation condition, the stability of density wave instability is not always enhanced by increasing the throttling coefficients at the inlet of channels.     

APC先进控制系统在焦化装置的应用

APC先进控制系统是一类基于数学模型的预估控制系统,是用多变量线性模型来描述过程的动态特性、用模型预测过程输出轨迹与希望轨迹的距离作为控制质量指标,求得最优的控制策略。利用先进控制技术满足装置安全平稳操作的要求、提高装置加工能力和高附加值产品收率,是国内外炼化企业普遍采用的技术手段。洛阳石化延迟焦化装置设计加工能力为140×104t/a,该装置采用APC先进控制后,增强了装置的抗干扰能力,提高了装置生产的平稳性,减轻了操作人员的工作负荷。但在焦炭塔预热、切塔、大吹汽等重要操作节点,生产工况变化较大,APC先进控制系统存在一定程度的滞后性,造成控制系统紊乱。根据系统热量和物料变化,提出了操作变量和被控变量在各重要操作节点的设置原则,在不切除APC控制系统的情况下,通过改变变量上、下限数值,来增强装置的抗干扰能力。通过对比APC先进控制系统投用前后的产品质量、关键操作参数,装置实现了卡边控制,目的产品收率、处理能力和装置效益得到提高,分馏系统和吸收稳定系统的稳定性有所增强。     

An introduction to Chinese manufacturing research institutions

The manufacturing environment has dramatically changed in the last few years. Worldwide competition among manufacturers and the development of new manufacturing technologies have contributed to today's competitive situation in many manufacturing areas. Advanced computer technology is the driver that has made global manufacturing competition possible. In this paper, the current research of advanced manufacturing technology at major institutions in China is introduced.     

Feasibility study of polyurethane shape-memory polymer actuators for pressure bandage application

Abstract

The feasibility of laboratory-synthesized polyurethane-based shape-memory polymer (SMPU) actuators has been investigated for possible application in medical pressure bandages where gradient pressure is required between the ankle and the knee for treatment of leg ulcers. In this study, using heat as the stimulant, SMPU strip actuators have been subjected to gradual and cyclic stresses; their recovery force, reproducibility and reusability have been monitored with respect to changes in temperature and circumference of a model leg, and the stress relaxation at various temperatures has been investigated. The findings suggest that SMPU actuators can be used for the development of the next generation of pressure bandages.     

自动变负荷及优化控制在空分设备中的应用

综述国内外大型空分设备的自动变负荷及优化控制技术的发展状况,分析自动变负荷及优化控制技术的难点,结合国内首套国产空分装置的自动变负荷及优化控制应用情况,对空分设备自动变负荷及优化控制的系统结构和操作流程等进行了较全面的阐述。     

Reliability analysis of plane elasticity problems by stochastic spline fictitious boundary element method

In this paper a stochastic spline fictitious boundary element method (SFBEM) is proposed for reliability analysis of plane elasticity problems in conjunction with the advanced first-order-second-moment (AFOSM) method. The AFOSM method has been demonstrated to be a reliable and practical approach to the structural reliability analysis, yielding results of reasonable accuracy for the engineering applications. And as a modified method for the conventional indirect boundary element method, SFBEM can provide accurate numerical solutions at high efficiency in deterministic analyses. For the purpose of structural reliability analysis, SFBEM is introduced during the iteration process of the AFOSM method, to obtain the required values of structural responses and their derivations with respect to the random variables considered. The use of SFBEM in the formulation of the AFOSM method makes it unnecessary to construct an explicit expression to the implicit limit state function of the problem, leading to a higher efficiency and better accuracy. The present approach is validated by comparing calculated solutions with those of Monte Carlo simulation for a number of example problems and a good agreement of the results is achieved.     

Degradation of sulfamethoxazole in water by solar photo-Fenton. Chemical and toxicological evaluation

In this work, the photocatalytic degradation of the antibiotic sulfamethoxazole (SMX) by solar photo-Fenton at pilot plant scale was evaluated in distilled water (DW) and in seawater (SW). Degradation and mineralization of SMX were strongly hindered in SW compared to DW. The influence of H₂O₂ and iron concentration on the efficiency of the photocatalytic process was evaluated. An increase in iron concentration from 2.6 to 10.4 mg L⁻¹ showed only a slight improvement in SMX degradation and mineralization. However, an increase in H₂O₂ concentration up to 120 mg L⁻¹ during photo-Fenton in DW decreased SMX solution toxicity from 85% to 20%, according to results of Daphnia magna bioassays. The same behaviour was not observed after photo-Fenton treatment in SW. Despite 45% mineralization in SW, toxicity increased from 16% to 86% as shown by Vibrio fischeri bioassays, which suggests that the intermediates generated in SW are different from those in DW. A SMX degradation pathway during the photo-Fenton treatment in DW is proposed.