盾构机推进液压系统的闭环控制仿真分析

结合某型盾构机特点,提出盾构机推进系统的闭环控制容积调速技术.其工作原理是通过液压缸的反馈信号,调节比例变量泵的输出流量和比例减压阀的出口压力,满足系统的推进速度和压力要求,实现连续控制.在AMESim环境下对系统的比例变量泵、比例减压阀和液压缸进行模型构建,并对推进系统进行动态特性仿真分析.通过仿真结果验证仿真模型的正确性,同时说明该系统适应特性和响应特性良好,为实际工程需要提供依据.     

采样器气体流量闭环控制研究

针对传统采样器气体流量采用开环控制,随着抽气泵负载的增加引起气体流量的下降,导致采样气体体积误差偏大的问题,提出了闭环流量控制的气体采样器,并对其进行了研究。利用微型气体质量流量传感器、可调微型气泵及控制器组成了闭环控制系统,并结合带死区的增量PID控制算法和积分累积气体采样的方式,消除了采样流量由于负载的变化而引起的误差。最后通过实验证明了闭环控制的采样器气体流量具有较好的线性度及较高的精度。     

基于模糊PID的电子水泵在线检测流量控制研究

目的:针对电子水泵在线检测系统工作时流量稳定时间长、稳定误差大的问题,研究一种更加高效、稳定的流量控制方式。方法:在传统PID控制方法的基础上引入模糊控制策略,设计一种实时优化PID控制的比例、积分、微分参数的模糊PID控制器;基于模糊PID控制器的设计完成了阀门开度-流量模型及传递函数的建立,以及包含参数整定的模糊PID主体设计;搭建了系统仿真模型,对比模糊PID与传统PID的仿真效果,并进行实验验证。结果:实验结果表明,模糊PID使单点流量控制稳定误差下降至±0.8%,稳定时间缩短至100 s。结论:采用模糊控制的PID调节策略能够提高电子水泵在线检测系统中流量控制的稳定性,还提高了检测效率。     

燃料柱塞泵流动特性仿真分析与低噪声设计

鱼雷燃料泵在对燃料增压时不可避免地产生强烈的振动并传递至鱼雷壳体,使之成为鱼雷的激振源之一。为了指导燃料泵的减振降噪,利用液压系统仿真软件AMESim建立了与传统斜盘式柱塞泵结构及工作原理差异很大的燃料柱塞泵的液压模型。搭建燃料泵动态压力测试系统,测试了燃料泵出口的动态压力,并与泵出口压力仿真信号进行对比,验证了模型的正确性。在此基础上,进一步对泵出口压力、流量及柱塞腔压力动态过程进行仿真,确定出了既能削除柱塞腔尖峰压力又对泵出口压力流量无影响的错配角。以此为指导,制造出具有合理错配角的样机。对比测试表明新泵相对原泵,在全部十个测试位置振动能级均降低,最大降幅约5 dB。     

电液伺服系统的微分与积分滑模变结构控制

针对电液系统的非线性特性及其参数不确定性,在电液伺服系统的速度跟踪控制中,提出了一种非线性微分与积分滑模变结构控制(DI-SVSC)策略。在滑模控制中引入积分控制项,消除了传统滑模变结构控制需要被跟踪信号导数已知的假设,利用一非线性微分控制消除了系统的抖振现象。在积分滑模控制与非线性微分控制中,分别给出了切换函数、非线性微分系数及控制器的设计方法。仿真结果显示,该控制方法具有较强的鲁棒性及良好的跟踪性能。     

基于AMESim恒功率变量泵的仿真研究

为了优化恒功率变量泵的动态调节特性,根据力士乐的轴向柱塞变量双泵A8V0泵的结构和工作原理,建立了恒功率泵的变量调节机构的数学模型;利用仿真软件AMESim进行仿真,分析2个测量弹簧参数对泵动态特性的影响.通过分析现有2个弹簧作用的恒功率调节的不足,提出了3个弹簧作用的变量调节机构.仿真结果表明:2个弹簧的变量调节机构...     

电液主动悬架单元测控技术研究

对由流量伺服阀构成的电液主动悬架进行了系统分析,设计了基于力、位移作为主要测量和反馈信号的PID控制器,仿真和台架实验结果表明,利用PID控制器进行电液流量伺服结构主动悬架控制,机构简单可靠,对于簧上质量加速度有明显的衰减作用.     

并联驱动电液系统振动控制策略研究

针对并联驱动电液系统的内力耦合问题,建立了振动系统的动力学模型,分析了干扰耦合的产生原因。利用自由度分解实现了多个激振器的独立控制,通过内力反馈解耦控制消除系统在运行过程中产生的耦合内力。在此基础上,利用三状态控制器对系统进行加速度闭环控制,改善系统的动态特性;通过引入前馈逆模型控制策略拓展系统频宽,利用并联驱动电液试验台对振动控制策略进行实验验证,试验结果证明提出的控制策略能够提高振动控制精度。     

充液成形设备双闭环控制分析

目的 研究先进充液成形设备的精度控制技术,以满足充液成形过程中对成形介质压力及侧推油缸位置的高精度控制要求,并确保模具型腔的密封性和零件成形的稳定性。方法 基于PLC控制器下的PID闭环控制功能,将速度闭环和位置或压力闭环进行集成,开发应用于液压系统的双闭环控制方法。结果 使用双闭环控制方法,可以调整侧推油缸的位置控制精度及响应速度,并将精度控制在0.1 mm以内,也可调整增压装置的输出端压力控制精度,使精度达到0.3 MPa。结论 在利用充液成形设备进行液压成形的过程中,双闭环技术可以实现设备侧向密封的精确位置控制以及型腔内压力的精确控制。     

不确定电液位置伺服系统的动态面跟踪控制

针对一类含有动态不确定性的双作用液压缸电液伺服系统跟踪控制问题,采用动态面控制方法设计了一个鲁棒自适应跟踪控制器.由于在逆推设计过程中加入了低通滤波器使得该方法不用对模型非线性进行多次微分,因而设计方法简化.所设计的自适应鲁棒控制器不仅能保证闭环系统的半全局渐近稳定,使得输出渐近跟踪期望轨迹;而且,跟踪误差可以通过控制器的设计参数加以调整.数字仿真结果表明,控制系统对给定位置的跟踪具有良好的动态特性,对系统的不确定性,具有较强的鲁棒性.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.