共查询到19条相似文献,搜索用时 187 毫秒
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先进实验超导托卡马克(EAST)作为国际上具有类似国际热核聚变实验堆(ITER)等离子体位型的全超导托卡马克之一,最近发展和建成了一套挤压成冰气动加速高频弹丸注入系统(PI-50),主要在EAST上用于等离子体边界局域模控制和芯部加料。PI-50弹丸注入器含有两个弹丸注入模块,并且配备了完善的供气系统。整个弹丸注入器的主要设计参数:发射弹丸频率为1~50 Hz可调,弹丸的尺寸为Φ1.5 mm×1.8 mm、Φ1.5 mm×1.5 mm和Φ1.5 mm×1.2 mm,弹丸发射速度为150~250 m/s。最近该系统已经完成了台面测试,获得了初步的测试结果。目前,PI-50系统的辅助真空抽气系统、低温系统、弹丸传输管道以及该系统本身已经全部安装到EAST实验现场。相关的联机调试将会在2017年EAST下半年的物理实验中进行。 相似文献
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^3He低温热力学性质实验数据综述;液氧密度标准计量装置的研制;液氮温区重力辅助深冷回路热管的实验研究;液氢管路绝热设计与效果分析;液化天然气冷能利用发电技术浅析;行波热声发动机驱动的脉管制冷机研究;EAST超导托卡马克热负荷波动对低温系统液氦槽的影响 相似文献
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吕步云 《制冷空调与电力机械》2002,23(3):44-45,57
从一个实际开发的产品,分析了采用双压缩机系统组成小型中央空调机组的电器回路组成和控制电路功能,叙述双压缩机系统运行的控制特点。 相似文献
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跟踪系统中多闭环控制模式的分析和实现 总被引:1,自引:0,他引:1
实现高精度跟踪,尤其在外界干扰力矩下,必须增加系统刚度来提高系统的扰动抑制能力.提出将加速度反馈引入常规的跟踪系统控制方式中,实现了由电流环、加速度环、速度环、位置环构成的四闭环控制模式.高增益的加速度反馈为系统提供一个响应更快、带宽更宽的内环,克服了单纯速度反馈带宽窄的特性.首先从理论上分析和证明了该方法的意义,多闭环控制模式可以提高系统的刚度,从而增强系统的抗扰动能力;同时,在加速度反馈的基础上研制前馈控制器,能够进一步提高大速度目标的跟踪性能.在某一实际的系统中对多闭环控制模式进行了实验验证,结果表明:同以往的控制方法相比扰动抑制带宽由15 Hz 提高到30 Hz ;并且在10 Hz 以下频率获得了-30 dB 抑制能力. 相似文献
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Jan Riezebos 《国际生产研究杂志》2013,51(5):1455-1477
POLCA is a material control system designed for make-to-order or engineer-to-order companies. These firms have to cope with a high variety of customised products, and strong pressure to provide short throughput times. POLCA constrains the amount of work in progress on the shop floor in order to achieve a short average shop floor throughput time. Earlier work has shown that the POLCA system has the capability to reduce both the average shop floor throughput time and the average total throughput time, but it is only effective if the POLCA system has been appropriately designed. The design of the POLCA system is therefore being investigated and discussed in this paper. We give an extensive literature review and give attention to the authorisation mechanisms of POLCA, the design of control loops, the route-specific capacity signals (POLCA cards), and specific facilities needed to use the POLCA system in practice. Finally, we report on the design of a POLCA system in practice, the first complete implementation of POLCA in The Netherlands, and present the quick scan that was used in the design of the POLCA system for this SME. 相似文献
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The objectives of this article are: (1) to develop the fault trees for control loops in a way that they all appear in a proper form and as modules in the fault tree for the whole system; and also (2) to modularize each control loop in a system properly to establish its unit model. These two methods are essentially equivalent. Either of them can be applied to facilitate constructing fault trees for the whole system. To accomplish such equivalent or parallel objectives, we will first take the feedback and feedforward control loops in the heat exchanger system as examples and then: (1) construct the fault trees of deviations in controlled variable for the two control loops in the way that all of their non-basic terminal events should be deviations in variables on those streams that connect to the loop from their outside in the system; and (2) establish the unit model for each of such two loops. One of the purposes of (2), which will not be addressed here, is to regard each control loop as a dummy unit and hence reduce the system to facilitate system input and fault tree construction eventually for complete automation purpose. 相似文献
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为保证航空相机光学系统的有效性和较高的成像质量,根据相机的热环境和结构特点进行了热控设计。采用热隔离等被动热控措施延长系统的热时间常数,降低光学系统对外部热环境变化的灵敏度。建立了镜头和窗口组件的传热模型和热阻网络模型,并对其在极端工况下的最大漏热率进行了分析计算,得到保持光学系统恒温所需的加热功率,根据计算结果设计了加热回路和分配加热功率。针对热控设计和航空相机的工况进行了稳态和瞬态仿真分析,对加热功率进行了优化。镜头和窗口的稳态温度分布均在(20±1)℃范围内,表明漏热补偿效果较好;瞬态分析结果表明,在飞行拍摄的过程中,温控系统将光学系统的温度控制在17.5℃~20.5℃范围内,满足热控指标要求,为提高光学系统的可靠性和热控设计优化提供了理论依据。 相似文献
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The excitation current of magnetic pole windings in magnetic flux pump needs to be generated by a control system. In this paper, the control system of pulse-type high temperature superconducting magnetic flux pump is discussed in detail. The control system consists of a control circuit and a drive circuit. A direct current power supply is the unique power supply of the drive circuit. The control circuit is powered by a computer through a USB interface of the computer. The control circuit receives commands from the computer and controls the drive circuit to generate different pulse waves. Each pulse wave generates a unique pulse-type traveling magnetic field and will pump magnetic flux into the superconducting loop. Experiments have been performed to examine the pumping effect of different pulse waves on both MgB2 and Bi-2223 superconducting loops using the proposed control system, and the best pulse wave has been found. The experimental results show that the magnetic flux pump can compensate current decay up to 32.5 A for MgB2 loop and 129 A for Bi-2223 loop. It indicates that the control system of the pulse-type magnetic flux pump is effective and feasible. 相似文献
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高精度位置随动系统的误差源分析 总被引:1,自引:0,他引:1
以经典三闭环控制系统为研究对象,对其误差源做了较为详尽的分析,将系统误差分为通过算法可调节的误差和通过算法无法调节的误差两大类.文中对舍入误差、传感器量测误差、采样率误差和带宽引入的误差这四种主要的误差源做了定量分析,并从物理运动学角度按由内环到外环的顺序分析了这几种误差在环间的传递与叠加.通过这种对误差的定量分析,可以直观的观察各类误差在总误差中所占的比重,为有针对性的设计系统提供了重要的理论依据.最后以某光电量测设备为控制对象进行了实验,实验结果表明该误差源分析理论是可行的. 相似文献
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Molecular fluctuations are known to affect dynamics of cellular systems in important ways. Studies aimed at understanding how molecular systems of certain regulatory architectures control noise therefore become essential. The interplay between feedback regulation and noise has been previously explored for cellular networks governed by a single negative feedback loop. However, similar issues within networks consisting of more complex regulatory structures remain elusive. The authors investigate how negative feedback loops manage noise within a biochemical cascade concurrently governed by multiple negative feedback loops, using the prokaryotic tryptophan (trp) operon system in Escherechia coli as the model system. To the authors knowledge, this is the first study of noise in the trp operon system. They show that the loops in the trp operon system possess distinct, even opposing, noise-controlling effects despite their seemingly analogous feedback structures. The enzyme inhibition loop, although controlling the last reaction of the cascade, was found to suppress noise not only for the tryptophan output but also for other upstream components. In contrast, the Repression (Rep) loop enhances noise for all systems components. Attenuation (Att) poses intermediate effects by attenuating noise for the upstream components but promoting noise for components downstream of its target. Regarding noise at the output tryptophan, Rep and Att can be categorised as noise-enhancing loops whereas Enzyme Inhibition as a noise-reducing loop. These findings suggest novel implications in how cellular systems with multiple feedback mechanisms control noise. [Includes supplementary material]. 相似文献
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针对惯性平台稳定回路中采用速率陀螺构成单速度环伺服控制系统的不足,本文提出采用直流测速机为电机转速测量反馈元件构成数字速度内环,采用陀螺为载体转速测量元件构成数字稳定外环组成双速度闭环串级控制结构.在常规的跟踪系统PI控制方式中,实现了由电流环,速度环,稳定环构成的三闭环控制模式,并和电流环,单速度稳定环构成的双闭环控制方式进行比较.实验结果表明:在扰动频率较高环境下,采用单速度环即可获得较好的稳定精度.而采用双速度环提高了系统对低频的抑制能力,并且对摩擦等非线性因素有更好的抑制作用. 相似文献