指针式压力表全自动检定系统的研制

本文介绍了一种指针式压力表全自动检定系统。该系统包括标准压力自动产生系统及仪表示值自动判读系统两部分。该系统检定速度快、检定效率高,可用以检定０～１６ＭＰａ、０．４级以下的压力表。本系统的研制对于改善目前国内压力表检定工作的落后状况,实现压力表检定的自动化具有重要意义。     

一种低成本的液压测试方法

目前,在国内的航空发动机试验台上对液体压力的测量主要有两种方法：一是使用普通的国产硅压阳传感器＋数据采集系统的“中式”方案,二是采用进口的成套式的数字化液体压力测量系统的“西式”方案。前者有采购成本低的优点,但维护校准工作量大,测点增加灵活性差,后者使用维护方便,但采购成本居高不下。本文在详细分析了它们的各自优势和不足后,提出了一种新的组合型的测试方案,该方案可以在确保原来两种测试系统的主要优点,并满足车台对液压测量的实际精度要求的基础上,将压力测试系统的采购成本降至原来的四成左右。为广大压力测试方面的工程技术人员提供了一种新的低成本选择方案。     

Development of remote calibration system for pressure standard

A remote calibration technology for disseminating pressure standard has been developed. In the remote calibration, a transfer standard is transported from a calibration laboratory to a client’s site where a calibration item is used. Using the transfer standard and the internet, the calibration item is calibrated on site. For the remote calibration, integrated transfer standards were newly developed in different pressure ranges. Each transfer standard includes a pressure controller, two or three precise pressure transducers, environmental measurement devices and an inclinometer in one box. Also the calibration protocol was examined to perform the remote calibration efficiently using the transfer standard. In order to prove the effectiveness of the remote calibration, the demonstration experiments were performed domestically and internationally. Here, the calibration protocol for the remote calibration and the functional overview of the newly developed transfer standards are described. The experimental results are also shown.     

A calibration system for PTU devices

Devices measuring pressure, temperature and humidity simultaneously are known as PTU devices. There are hardly any commercial calibration systems for the PTU devices available for low temperatures (<0 °C). To obtain more comprehensive data on the performance of PTU devices, a new calibration system is developed at MIKES. In this PTU Apparatus, pressure, temperature and humidity can be controlled simultaneously so that all combinations over the ranges are possible. The nominal ranges of the system are the following: absolute pressure 500–1100 hPa, temperature −52 °C to +80 °C and relative humidity 10–95%. The target uncertainties (k = 2) of the pressure, temperature and humidity are 10 Pa, 0,1–0,3 °C and 1–3% RH, respectively. The construction and operation as well as the results of operational tests of the PTU Apparatus are reported in this paper.     

压力传感器动态性能分析与动态补偿

在对炮口冲击波测试中，压力传感器的动态性能指标是否满足测量要求至关重要。本文通过GLS(SF)方法建立压力传感器的数学模型，并由数学模型求出动态性能指标。然而该传感器的动态性能指标不能满足测量要求，针对此问题本文采用零极点相消的方法设计出动态补偿滤波器，明显提高了该传感器的动态性能，最终解决了该冲击波的测量问题。     

Air flow rate thermal control system at low pressure drop

Low pressure drop thermal Mass Flow Controllers are generally thought to fulfill needs concerning the realization of a dynamic reference gas mixture generator for accurate gas analysis. A small air flow rate at low pressure drop must be controlled in a stable and precise way in the generator. True operative pressure drop limits, set point reproducibility, calibration needs and flow rate stability during operations were investigated for a low pressure drop thermal Mass Flow Controller. The flow rate bias due to late calibration and flow rate short-term stability were measured and discussed. The Allan method was used to calculate stability during operation. Calibration uncertainty, bias for late calibration, stability and set point reproducibility were composed to calculate the total uncertainty of the flow rate as a function of the operation time. Results show that it is possible to operate below the target uncertainty stated for a dynamic generator of gas mixtures down to 100 Pa pressure drop. Stability gives the main contribution to total uncertainty at very short operation times, while calibration uncertainty gives the main contribution to total uncertainty at normal operation times. The calibration uncertainty at 0.1% is low enough to assure the target uncertainty for operation times over 10 s. Daily verification of calibration enhances the reliability of the measurement. An accurate voltmeter is necessary for the reproducibility of the set point.     

Analysis of pressure distribution for the various gas flow vacuum system in the range from 1 Pa to 133 Pa

The measurement and control of gas flow are critical in many manufacturing processes. Semiconductor manufacturers, in particular, require a number of different process gases for etching, deposition, oxidation, doping and inerting applications. In many of these, as well as other industrial and research processes including measurement of partial pressures with residual gas analyzers (RGAs), calibration of vacuum gauges, and conductance of a conductance-reducer , accurate measurement and stability of the gas pressure within the reaction vacuum chamber is essential. In the present work, pressure distribution in the chamber of a newly developed flow control system was investigated for three gases (Ar, N₂, and He) range from 1 Pa to 133 Pa. For all the gases, the relative deviations in pressure distribution near the gas inlet and outlet were in the range of −1.3% and 1.2% respectively.     

薄膜式锰铜传感器——一种新型的超高压力传感器

文中综述了动态高压锰铜传感器最近十多年来的研究现状,着重介绍了一类新型的锰铜传感器———薄膜式锰铜传感器的研发进展。该类传感器的研制旨在提高传感器高压测试极限和缩短响应时间。目前已进行了直到80GPa以下的初步标定,响应时间最快达32ns     

Dynamic calibration method of high-pressure transducer based on quasi-δ function excitation source

This paper presents a dynamic calibration method of frequency response characteristics of high-pressure sensor. In this method, the pressure sensor was under high hydrostatic pressure in advance, then use the bullet impacted Hopkinson bar and generated quasi-δ function signal with small amplitude, which excited the sensor being calibrated. The excitation signal of sensor are collected, at the same time, output signal of the sensor are collected, and at last, the collected data are processed according to calibration principle and calculated the frequency response of the sensor being calibrated. This calibration method realized dynamic calibration of high pressure sensor under actual working pressure; it can realize the low limit frequency of the calibrated frequency range strictly reaches to zero frequency. This method can also be applied to acceleration sensor, transient high-temperature sensor, and other types of sensors. In this paper, the calibration principle of quasi-δ function dynamic calibration method is introduced. The relationship among pulse width of excitation signal, frequency range that can be calibrated and calibration precision is analyzed. The experimental results are also shown.     

A novel approach based on artificial neural network for calibration of multi-hole pressure probes

Imperfections in the manufacturing process of flow measuring probes affect their measuring behavior. Nevertheless, in order to provide the highest possible accuracy, each individual multi-hole pressure probe has to be calibrated before using them in turbomachinery. This paper presents a novel method based on artificial neural networks (ANN) to predict the flow parameters of multi-hole pressure probes. A two-stage ANN approach using multilayer perceptron (MLP) is proposed in this study. The two-stage prediction approach involves two MLP networks, which represent the calibration data and the prediction error. For a given set of inputs, outputs from both networks are combined to estimate the measured value. The calibration data of a 5-hole probe at RWTH Aachen was used to develop and validate the proposed ANN models and two-stage prediction approach. The results showed that the ANN can predict the flow parameters with high accuracy. Using the two-stage approach, the prediction accuracy was further improved compared to polynomial functions, i.e. a commonly used method in probe calibration. Furthermore, the proposed approach offers high interpolation capabilities while preventing overfitting (i.e. failure to fit new data). Unlike polynomials, it is shown that the ANN based method can provide accurate predictions at intermediate points without large oscillations.     

An initial investigation of the damped resonant behaviour of gas-operated pressure balances

The aim of this investigation into the damped resonant behaviour of the piston of gas-operated pressure balances is to provide insights into ways of improving the short-term performance of gas-operated pressure balances. Initial measurement results are reported for the damped resonant behaviour of two different pressure balances as a function of system volume. The pressure balances are operated using air in absolute mode at 100 kPa and the system volume is varied from about 10 mL to 250 mL. Values for the period, the logarithmic decrement λ and the Q of the oscillation are obtained by fitting the measured damped oscillatory motion of the piston height to a classical damped oscillator model. Results show that the damping is dominated by non-adiabatic pressure variations in the system volume and not by viscous damping of the vertical motion of the piston in the cylinder. The settling time for the oscillations to damp out is primarily determined by the period of oscillation with a lesser influence from variations in λ. Implications for improving pressure balance performance are discussed.     

一种高精度自动压力标准源的设计

通过设计一种高精度自动压力标准源,可满足准确度等级0．1级及以下压力传感器、数字压力计、压力表等压力仪器仪表的检定和校准工作,量程范围覆盖绝大多数常用压力仪器仪表的量程,具有造压迅速、稳定、便携、自动化程度高、操作方便快捷等特点,用于相关测试设备压力参数的现场及实验室计量保障,可极大的减轻计量人员的操作强度,提高仪器仪表的计量检定效率。     

Characterization of MEMS piezoresistive pressure sensors using AFM

Atomic force microscope (AFM) is adapted to characterize an ultrasensitive piezoresistive pressure sensor based on microelectromechanical system (MEMS) technology. AFM is utilized in contact mode to exert force on several different micromachined diaphragm structures using a modified silicon cantilever with a particle attached to its end. The applied force is adjusted by changing the trigger voltage during each engage step of the probe-tip on the diaphragm surface. The contact force is determined from the force plots obtained for each trigger voltage in advanced force mode. Low force values in the range of 0.3–5 μN have been obtained with this method. This force induces strain on the bridge-arm of the diaphragm where the polysilicon resistor is located. The resultant change in the resistance produced due to varying force/pressure is measured using a delta mode current–voltage (I–V) measurement set-up. The contact mode AFM in conjunction with a nanovoltmeter enables the calibration of very sensitive force sensors down to 0.3 μN.     

An investigation of quartz type pressure transducer behavior under continuous pressure conditions and metrological characterization

In this work the behavior of high accurate quartz based pressure transducer under the continuous pressure conditions was investigated and metrologically characterized. Paroscientific digiquartz pressure transducer which belongs to the pressure laboratory of INRIM was chosen as a device. First measurements were realized in INRIM and UME in 2005. Two different measurement procedures were applied. The pressure was applied at each pressure points approximately during 25 min to observe the behavior of transducer under applied continuous pressure conditions. The results of standard calibration procedure were compared with the results of applied continuous conditions procedure. The same measurements were repeated in INRIM and UME in 2010 to compare the results taken from 2005 to 2010 and the long term stability was evaluated.     

测压铜球温度修正方法研究

介绍了铜球准动态标定的含义及高低温铜球压力编表方法；针对塑性测压器材温度修正的两种思想－压力修正及变形量修正，运用量纲分析及相似理论推导了变形量修正方法环境温度对铜球压力影响的无量纲相似比；借助于不同环境温度下得到的测压铜球的准动态标定数据，运用回归分析技术导出了压力及变形量修正公式；并用两批次铜球的高低温准动态标定实验进行了验证及两种方法的比对。     

压痛阈测量仪的研制

介绍一种能定量检测人体不同部位压痛力度的新仪器。作为新的工具,它可方便地用于病人压痛阈值的检查和评价：用于人体经张的研究。该仪器采用受环境温度影响小的硅油做为传感器的太力传导介质,并设计出５种不同表面积的测压头,以满足不同测量部位的需要。该仪器还采用了数字锁定功能,方便了使用。     

Pressure control of hydraulic servo system using proportional control valve

The purpose of this study is to develope a control scheme for the hydraulic servo system which can rapidly control the pressure in a hydraulic cylinder with very short stroke. Compared with the negligible stroke of the cylinder in the system, the flow gain of the proportional pressure control valve constituting the hydraulic servo system is relatively large and the time delay on the response of the valve is quite long. Therefore, the pressure control system, in this study tends to get unstable during operations. Considering the above mentioned characteristics of the system, a two-degree-of-freedom control scheme, composed of the I-PDD²… feedback compensator and the feedforward controller, is proposed. The reference model scheme is used in deciding the parameters of the controllers. The validity of the proposed control scheme is confirmed through the experiments.     

核电用节流管伺服调压阀控制系统研究

介绍了节流管调控式调压阀用低功率高精度控制系统,包括系统原理与组成、以PLC为中枢的控制系统、软件设计和调试试验等,该控制系统功率低,控制精度高,可靠性好,满足核电用节流管伺服调压阀的使用要求。     

A study on the improvement of the load pressure feedback mechanism of the proportional pressure control valve

The proportional pressure control valve having versatile functions and higher performance is an essential component in the open loop controlled rear wheel steering gear of the four wheel steering system on a passenger car. In this study, the authors suggest a new type of load pressure feedback mechanism which can make it easy to change the control range of load pressure without changing the capacity of solenoid. The concept of the suggested mechanism, composed of the pressure chamber with throttles in series, was described. The mathematical model was derived from the rear wheel steering gear system consisting of a valve and a cylinder for the purpose of analyzing the valve characteristics. And the programme for computing the characteristic of the valve was developed. Experiments were carried out to confirm the performance of the valve and computations were performed to ascertain the usefulness of the developed programme. The results from the computations fairly coincide with those from the experiments. The results from the experiments and computations show that the performance of new valve is as good as that of the already developed one and the new valve has an advantage in the easiness in varying the control range of load pressure.     

Proficiency test for effective area determination of a pneumatic pressure balance in Mexico

A pneumatic pressure proficiency test for effective area determination of a pressure balance was performed among 4 accredited calibration laboratories in Mexico. CENAM provided the reference values (making initial and final calibrations) and was the pilot laboratory. The Mexican Accreditation Entity (ema) collaborated. The participants calibrated, by cross floating, a Wika pressure balance model CPB 5000 with accuracy class 0.015% of the reading in the range 0.7–7 MPa. The calibration pressures were 0.7, 1.4, 2.1 3.5, 4.2, 5.6 and 7.0 MPa. For A₀ and A_e, the normalized error equation was used to compare the results of the laboratories with CENAM’s reference values. The results obtained were satisfactory (E_n did not exceed the compatibility limit, −1 ⩽ E_n ⩽ 1).