温度仪表失控保护方法

通过对钟罩式气体流量标准装置的不确定度分析，确定了该标准装置的合成标准不确定和扩展不确定度，为气体流量计的检定提供了依据。     

钟罩式气体流量标准装置的不确定度评定

通过对钟罩式气体流量标准装置的不确定度分析，确定了该标准装置的合成标准不确定度和扩展不确定度，为气体流量计的检定提供了依据。     

微型计算机在气体流量标准装置上的应用

一、概述我厂校验各式气体流量计是采用传统的操作方法,即用钟罩式(又称浮筒式)气体流量标准装置作为标准容器,在校验时配合秒表,管路联接(见图1)。由一人操纵调节开关1,按被校流量计2的某一校验点保持流量恒定,气流经流量计2、导管8旋入浮筒4,使浮筒均恒上升,带动刻度盘6进转(刻度盘的刻线是按浮筒的容积进行定度的,以升为单位);由另一人用秒表选定并记录浮筒在一定容积范围内此V_1到V_2的运动时间t,然后按定义公     

平均值-极差控制图在音速喷嘴式气体流量标准装置测量过程中的应用

音速喷嘴式气体流量标准装置是气体流量重要的计量标准，其测量过程的情况直接反映了装置的准确性、重复性、稳定性。使用控制图可以记录装置的测量过程，并由此判断其测量过程是否处于受控状态。本文介绍了平均值-极差控制图在音速喷嘴式气体流量标准装置测量过程中的应用。     

正压法音速喷嘴气体流量标准装置的建立

介绍了一种正压法音速喷嘴(临界流流量计)气体流量标准装置.详细论述了其工作原理、各个分系统组成及其功能特点.分析了该装置的测量不确定度,并通过试验验证了该装置的计量性能技术指标.     

正压法音速喷嘴气体流量标准装置压力调节改造

正压法音速喷嘴气体流量标准装置由于能提供尽量接近使用工况的校准条件,近年得到了广泛的应用。但由于其前端采用空压机供气,系统压力不易控制。本文提供了一种解决系统压力波动和控制系统压力的方法。该方法采用稳压装置前加带反馈的流量调节阀。改造后系统压力可以得到很好的控制。     

自力式压力调节阀在正压法音速喷嘴标准装置中的应用

保持喷嘴前滞止压力稳定是正压法音速喷嘴气体流量标准装置设计中的关键问题,本文中采用自力式压力调节阀对装置中压力进行调节控制,取得预期的效果.     

成飞公司通过波音公司D1-9000A评审

1999年 1 1月 1 5日至 1 8日 ,波音公司根据与成飞公司的转包生产合同 ,派遣评审组按波音公司Ｄ1 -90 0 0Ａ《先进质量体系》标准的要求 ,逐条评审了成飞公司质量体系的符合性。评审内容包括 :质量体系文件、质量审核检查单、内部审核报告和对生产现场进行抽查等。　　由于成飞公司对评审工作组织严密、安排得当及配合有力 ,从而使波音公司评审组提前完成全部评审工作。在 1 1月 1 8日召开的末次会议上 ,评审组高度评价了成飞公司在质量体系建设上取得的成功 ,认为成飞公司已拥有一个符合Ｄ1 -90 0 0Ａ要求的质量体系 ,并向成飞公司颁发了生…     

主动式活塞液体流量标准装置设计中测量不确定度评估

主动式活塞液体流量标准装置是容积时间法标准装置的一种.本文叙述了主动式活塞液体流量标准装置在设计中进行的测量不确定度评估.     

特殊孔板设计的应用

引言在工业生产中,标准节流装置应用十分广泛,但是只有在符合标准要求的技术条件下,才能使用标准节流装置正确地测量流量。而在工程实际应用中,当雷诺数远小于标准推荐使用的最小雷诺数、标准节流装置的流量系数变化过大而不能使用时,需要采用一些非标准形式     

粒子分离器气动特性数值研究

本文利用张量分析建立了三维贴体坐标系上的通用输运方程;采用贴体网格计算了粒子分离器二相流的三维流场;建立了三维的粒子运动轨迹微分方程,理论上分析了粒子分离器结构设计对其性能的影响,与试验结果吻合较好。     

座舱蒙皮外表面气动加热的物理仿真研究

座舱蒙皮外表面气动加热的物理仿真是座舱热特性试验研究的重要基础。把平行射流理论应用于座舱蒙皮外表面气动加热的物理仿真,提出了气动加热物理仿真的新方法。该方法能够满足座舱动态热特性物理仿真的需要,且在人力、物力上较省。提出了用数学仿真控制座舱热特性试验的方法。这些方法已成功地应用于飞机座舱热载荷和热特性试验中。     

Stable Supervisory-Adaptive Controller for Spinning Satellite using Only Magnetorquers

In this paper, an adaptive controller for spinning satellites has been designed to achieve high attitude accuracy. In the cases which magnetorquers are used as actuators, the generated torque is perpendicular to the Earth's magnetic field, so a satellite is not completely controllable. In addition, the maximum value of achievable torque is limited due to capacity of magnetorquers. Hence, implementation of adaptive control law causes attitude error in system and also decreases the speed of response. To overcome these problems, a supervisory-adaptive controller has been designed. In this regard, sliding control has been used as a supervisory controller to correct the control signal applicable to magnetorquers. As a result of this method, stability of the system has been proved, output error has been decreased, and speed of response has been increased.     

从疲劳试验寿命到结构安全寿命

1.可靠度与寿命分布分散系数 先考虑固定试验条件下的寿命分散,将疲劳寿命T这一随机变量的概率分布函数记为F(t),其密度函数为f(t),那么在某个时刻t_R,结构可靠度(即存活概率)R为     

基于信息融合的航空发动机剩余寿命预测

利用航空发动机状态监测信息,考虑到信息本身具有的误差性和随机性等特点,采用贝叶斯线性模型融合了监测信息,实现了综合利用多源信息的进行航空发动机性能衰退评估;以性能衰退评估结果为输入变量,建立基于Gamma随机过程的可靠性评估模型,预测在指定性能可靠性水平下的剩余寿命.通过算例,分析了不同监测参数对剩余寿命预测的影响.该方法能将性能监测与可靠性分析集成到一个框架中,充分利用了多种状态监测信息,结果更加准确,更符合控制航空发动机维修决策风险的实际.      

一种安全的身份认证模型的研究与实现

研究分析了Radius身份认证协议,就其在安全性方面的不足给出了解决办法,同时根据给出的解决方案构建一种身份认证模型,最后对新构建的模型进行安全性分析,通过实例证明该模型是安全的、可靠的、实现简单的、并具有很强的实用价值。     

尾迹与涡轮叶栅边界层的相互作用

通过实验和数值模拟的手段研究了尾迹与边界层的相互作用,其中上游叶排尾迹的模拟是通过在涡轮叶栅前设置周期性运动的圆柱实现的.研究表明,上游尾迹对涡轮叶栅边界层的发展有显著影响,在其作用下,吸力面边界层提前转捩,分离得到明显的抑制,利用尾迹与边界层相互作用的非定常效应可以明显提高低压涡轮叶栅气动负荷.      

某型串列静子的三维气动数值优化设计

针对某型高负荷轴流压气机串列静子近轮毂处存在的分离,利用自行开发的压气机三维气动数值优化设计平台,选择复合形优化方法,通过修改串列静子近轮毂处的三维积叠方式对串列静子进行了优化设计.结果表明,优化设计取得了良好效果,在消除分离的同时,有效提高了压气机的整体性能.      

Achieving security in integrated circuit card applications realityor desire?

It has always been claimed that smart cards provide a really high level of security, considering them as a tamper-proof device, with the possibility to auto-block some or all of the services it provides. Unfortunately, nowadays some hackers appear to have demonstrated the lack of security involved in some applications where Integrated Circuit Cards (ICC) have been used. This has led to the opinion that smart cards are not secure enough, and their security is only in the minds of the commercial companies involved with the technology. In this paper, the author explains the reasons why this hacking has succeeded. For example, sometimes memory cards have been used instead of smart cards, or very old smart cards have been issued and not renewed, or the development team involved has not used basic security techniques, such as diversified keys. The author also gives clues to achieve a high level of security depending on the final application, and the environment in which it is going to be used     

Preliminary design and optimization of slotted tube grain for solid rocket motor

In this paper,design and optimization technique of slotted tube grain for solid rocket motors has been discussed.In doing so,the design objectives and constraints have been set,geometric parameters identified,performance prediction parameters calculated,thereafter preliminary designs completed and finally optimal design reached.Geometric model for slotted tube grain configuration has been developed.Average thrust has been taken as the objective function with constraints of burning time,mass of propellant,fixed length and diameter of chamber case.Lumped parameter method has been used for calculating the performance prediction parameters.A set of preliminary designs has been completed and an analysis of these results conducted.Although all the preliminary results fulfill the design requirements in terms of objective function and constraints,however in order to attain the optimal design,Sequential quadratic programming optimization technique has been adopted.As the slotted tube grain geometry is totally dependent upon various independent variables and each of these variables has a bearing on explicit characteristic of grain designing,hence affects of the independent variables on performance parameters have been examined,thus variation laws have been developed.Basing on the variation laws and the analysis of preliminary design results,upper and lower limits have been defined for the independent geometric variables and an initial guess provided for conducting optimization.Results attained exhibits that an optimal result has been attained and the value of objective function has been maximized.All the design constraint limits have also been met while ensuring sound values of volumetric loading fraction,web fraction and neutrality.This methodology of design and optimization of slotted tube grain for solid rocket motors can be used by engineers as a reference guide for actual design and engineering purposes.