定容式流导法微流量校准装置

定容式流导法微流量校准装置是气体微流量的计量标准,可采用定容法和流导法对气体微流进行校准,校准范围为(5×10-2～5×10-11)Pa·m3/s,合成标准不确定度为0.56%～1.7%.     

动态流导法真空校准装置的性能测试

介绍了动态流导法真空校准装置的校准原理、校准方法,测试了性能指标,校准了分离规和磁悬浮转子规.实验结果表明,校准范围为(2.6×10-7～2.4×10-1)Pa,不确定度小于1.4%,磁悬浮转子规的校准结果与德国PTB的校准结果的一致性好于1.6%.     

动态流量法超高真空标准装置

研制成功的动态流量法超高真空标准装置是一台用来校准真空规的绝对真空计量标准。装置由校准系统、微流量计系统、抽气系统和计算机控制系统组成。校准系统采用四球结构 ,校准球室直径为50 0mm。极限真空度为 6 5× 10 - 9Pa ,校准范围为 10 - 2 ～ 10 - 7Pa ,不确定度为 3% (10 - 2 ～ 10 - 6 Pa)和10 % (10 - 7Pa)。     

现场真空校准装置性能研究

研制了一台校准范围为10~(-5)~10~5Pa的现场真空校准装置。将不同种类单一成分的校准气体引入装置上游室,通过几何尺寸为微米量级激光小孔的衰减,建立校准用标准压力p_(std)。上游室压力变化范围为1~10~3Pa,相应地,校准室内对应的标准压力范围10~(-5)~10~(-2)Pa(N2),测量不确定度为2.4%。另外,该装置可采用与标准真空计直接比较进行动态或静态校准,其极限真空度为10~(-6)Pa量级。对装置暴露大气后的抽气性能、静态压升及其主要计量特性进行了实验研究。实验结果表明,该装置外形尺寸以及质量分别为475 mm×420 mm×800 mm、37.8 kg,校准范围为1.9×10~(-5)~1.0×10~5Pa,相对合成标准不确定度为2.8%~0.40%。     

用定容式气体流量计进行真空规校准方法的研究

提出了一种采用定容式气体流量计校准真空规的方法,并对校准装置进行了不确定度的分析。定容式气体流量计有2种工作模式:采用定容法模式可以提供(10-8～10-2)Pa.m3/s的流量,采用固定流导法模式可以提供(10-6～10-11)Pa.m3/s的流量,2种方法组合提供的标准流量范围变宽,延伸了流量下限。定容式气体流量计相对于恒压式气体流量计,有结构简单、操作方便等特点。采用定容式气体流量计校准真空规的范围为(10-6～10-2)Pa,合成标准不确定度为(0.67～1.74)%。并用恒压式气体流量计校准同一分离规进行了比较,2个校准结果一致性好于5.7%。     

正压漏孔校准装置的研制

作者对正压漏孔校准方法作了研究,为了对不同示漏气体的正压漏孔进行精确校准,建立了一套改进型的PΔV/t漏孔校准装置,并对该装置进行了不确定度的分析.该装置校准范围1×10-4 Pa m3/s～1×10-7 Pa m3/s,在漏率2×10-6 Pa m3/s时系统总误差小于4.0%.     

真空计量标准的研制与应用

兰州物理研究所研制了一系列真空标准装置,可用于真空规、方向规、分压力质谱计、真空漏孔和正压漏孔的校准.其静态膨胀法真空标准装置、动态流量法真空标准装置及超高/极高真空校准装置是用于真空规校准的三套基础标准,覆盖的校准范围为(10-10～105)Pa;程控式真空规校准装置适用于工业部门,其校准范围为(10-4～105)Pa;为实现质谱计的校准,研制了一台具有三路相同独立进样系统的分压力质谱计校准装置,标准分压力通过磁悬浮转子规以两种不同的方法进行测量,该校准装置可实现(10-7～10-1)Pa范围内的分压力校准;为实现真空漏孔的校准,研制了恒压式气体微流量标准装置和固定流导法气体微流量标准装置.恒压式气体微流量标准装置的校准范围为(10-8>～10-2)Pa·m3/s,同定流导法气体微流量标准装置的校准范围为(10-10～10-5)Pa·m3/s,漏孔漏率的校准通过比较被校漏孔和标准气体微流量计在一台四极质谱计上引起示漏气体离子流的大小计算得到;为实现正压漏孔的校准,研制了一台正压漏孔校准装置,采用定容法和定量气体动态比较法对正压漏孔进行校准,校准范围为(5 × 10-5～10-1)Pa·m3/s;研制了一台定向流真空校准装置,实现对方向规的校准和非平衡态分子流的研究,装置的校准范围为(10-7～10-1)Pa.     

电推进系统工质气体微流量校准装置的设计

通过实验和理论分析,结合电推进系统工质气体微流量的实际使用情况,提出了绝压定容升压法及差压定容升压法两种电推进系统工质气体微流量的校准方法,设计了电推进系统工质气体微流量校准装置,装置采用双通道对称结构,包括抽气系统、校准系统、容积测量系统、稳压系统、多工质气路转换系统、恒温及烘烤系统、数据采集系统等,校准范围为5×10~(-5)～5×10~(-1)Pa·m~3/s,入口压力为0.2～0.5 MPa,出口压力为100 Pa～0.2 MPa,扩展不确定度小于2.0%(k=2),校准气体为Xe、Kr、Ar、He和N_2,可以满足电推进系统的计量需求。     

比较法校准氦真空参考漏孔漏率及合成不确定度评定

直接比对法是氦质谱检漏仪在稳定工作和引入气体相同条件下,将参考漏孔流出的氦气和标准漏孔提供的已知流量的氦气分别引入校准室中,用氦质谱检漏仪分别测量氦气产生的离子流,通过比较两次离子流的测量值计算出参考漏孔漏率的一种校准方法。这种校准范围为1×10-7Pa.m3/s~1×10-10Pa.m3/s。对同一参考漏孔,采用同样的校准测量,可以采用高斯分布统计的方法获得校准不确定度,其他不确定度分量由氦质谱检漏仪组成的校准装置决定,其合成相对不确定度可达到10%。     

便携式真空计校准装置

为了解决许多应用领域对真空度的现场校准需求,研制出便携式真空计校准装置.采用直径为200mm的球形容器作为校准室,用两台不同量程的电容薄膜真空计作为参考标准.为实现宽量程校准,装置集成了静态比对法、静态膨胀法及动态流量法三种校准方法.实验结果证实该装置的校准范围可达1×105～4× 10-6 Pa,合成标准不确定度为1.3％ ～4.7％.装置的外形尺寸为450 mm× 400 mm×750 mm,总重量小于40kg.总之,该装置具有体积小、重量轻、便携和成本低等优点.     

标准气体微流量计的性能测试

主要介绍标准微流量计的性能测试。测试结果表明；气体流量的测量范围为１７．１×１０－５～１．２２×１０－５ｐａ·Ｌ／ｓ，不确定度小于２％。     

动态灌液时间研究

阐述了动态灌装原理,推导了动态灌液时间计算公式,比较了理论动态灌液时间和实际短管灌液时间,为采用动态灌装法以提高生产能力提供了依据.     

COP-2协议的通过率分析

首先对空间数据系统咨询委员会定义的３种命令控制中以选择性重传为基础运行的ＣＯＰ－２协议作出分析，然后在协议中加入流控制机制，并对两种流控制模式的ＣＯＰ－２通过率进行了分析，最后讨论了系统参数对通过率的影响。     

Throughput centered prioritization of machines in transfer lines

In an environment of scarce resources and complex production systems, prioritizing is key to confront the challenge of managing physical assets. In the literature, there exist a number of techniques to prioritize maintenance decisions that consider safety, technical and business perspectives. However, the effect of risk mitigating elements—such as intermediate buffers in production lines—on prioritization has not yet been investigated in depth. In this line, the work proposes a user-friendly graphical technique called the system efficiency influence diagram (SEID). Asset managers may use SEID to identify machines that have a greater impact on the system throughput, and thus set prioritized maintenance policies and/or redesign of buffers capacities. The tool provides insight to the analyst as it decomposes the influence of a given machine on the system throughput as a product of two elements: (1) system influence efficiency factor and (2) machine unavailability factor. We illustrate its applicability using three case studies: a four-machine transfer line, a vehicle assembly line, and an open-pit mining conveyor system. The results confirm that the machines with greater unavailability factors are not necessarily the most important for the efficiency of the production line, as it is the case when no intermediate buffers exist. As a decision aid tool, SEID emphasizes the need to move from a maintenance vision focused on machine availability, to a systems engineering perspective.     

基于流量和时延的网络性能测量系统的研究

提出了一种间接测量网络吞吐率的新方法，建立了基于流量和时延的网络性能分析模型，基于这个模型对网络性能测量方法进行分析，设计并实现了一个基于流量和时延的网络性能测量系统，对网络性能进行了测量和分析。     

Pumping performance analysis on turbomolecular pump

The pumping speed, conductance, and throughput of turbomolecular pump are investigated by both experiment and numerical simulation. The mass flow rates varying from 0.2 to 19.2 sccm (standard cubic centimeter per minute) for various inlet pressures are conducted in experiment. The experimental and analytic pumping speeds versus the inlet pressures of turbomolecular pump for N₂ were revealed. The pumping speeds obtained from experimental and simulation analysis are consistent at inlet pressures ranged from 5 × 10⁻² to 8 × 10⁻² Pa. When the inlet pressure is below 10³ Pa, the conductance decreases because the flow enters the transition flow region. Finally, the influence of inlet pressure on the throughput is also reported.     

Effects of operating speed on production quality and throughput

A key determinant of a manufacturing system's performance is its operating speed. While it is generally assumed that overall production throughput increases with operating speed, this is not necessarily the case where quality deteriorates as a result of the higher speed. In this paper we derive a representative quality–speed relationship and examine the productivity implications. We develop models to capture the effects of rework, repair, and scrap on system throughput and illustrate the resulting trade-off between higher productivity and the need for additional processing. Empirical evidence is also presented to motivate the work.     

Local improvements that degrade system performance: case studies and discussion for throughput analysis

Much of our intuition about production system performance dynamics is grounded in an understanding of simple serial lines. For this reason, practitioners tend to rely on concepts and principles that have successfully guided the design and improvement of these lines, even in the analysis of significantly more complex systems. Based on this intuition, there is a natural tendency to believe that improving any specific feature of a system will result in comparable or improved overall performance. Unfortunately, this is not always the case. In this paper, we present three case study examples which demonstrate that local improvements to station speed or buffer capacity can result in an overall degradation of system performance for non-serial production systems.     

A methodology for throughput capacity analysis of a production facility considering environment condition

Throughput capacity of a production facility plays an important role in supporting managers and engineers in the decision making processes related to the design and optimization of a production plant. System throughput capacity is affected in complex ways by the reliability, maintainability, and capacity of its components. These in turn are considerably affected by operational environment such as ambient temperature, icing, dust, wind, etc. Therefore, in order to have an effective throughput capacity analysis (TCA), all influence factors (covariates) on these terms need to be identified; furthermore, their effect must be modeled and quantified by an appropriate statistical approach. The aim of this paper is to develop a methodology for throughput capacity analysis considering environment condition. A simple case study is used to demonstrate how the methodology can be applied in a real case.