安全阀性能检测系统的测量不确定度

分析了安全阀性能检测系统中的主要误差因素，对安全阀动作性能和排量系数的测量不确定度进行了初步计算。

误差与不确定度刍议

测量不确定度是现代误差理论的核心和最新发展。不确定度与误差有千丝万缕的联系，不确定度的标准偏差、合成、传播和扩展均是误差分析方法的推广并依赖于误差理论。但是，不确定度表征的是测量结果的分散性，误差是测量结果与被测量的真值之差。前者恒为正，后者可正可负。由于真值不可知，测量误差不可能准确知道，而测量不确定度则可定量评定。因此，两者不是一回事，切不可将误差等同于不确定度。

J_2级经纬仪竖盘指标自动补偿误差不确定度

介绍了按照ＪＪＧ４１４—９４《光学经纬仪》检定、校准Ｊ２级经纬仪竖盘指标自动补偿误差时，依据“’９３国际指南”要求，对其测量不确定度进行的分析、计算。

Research into Uncertainty in Measurement of Seawater Chemical Oxygen Demand by Potassium Iodide-Alkaline Potassium Permanganate Determination Method

Using the glucose and L-glutamic-acid to prepare the standard substance according to the ratio of 1：1, and the artificial seawater and the standard substance to prepare a series of standard solutions, the distribution pattern of uncertainty in measurement of seawater COD is obtained based on the measured results of the series of standard solutions by the potassium iodide-alkaline potassium permanganate determination method. The distribution pattern is as follows： Uncertainty in measurement is big and not constant at the high end, but small and constant at the low end.

Passive target tracking with intermittent measurement based on random finite set

In the tracking problem for the maritime radiation source by a passive sensor,there are three main difficulties,i.e.,the poor observability of the radiation source,the detection uncertainty(false and missed detections)and the uncertainty of the target appearing/disappearing in the field of view.These difficulties can make the establishment or maintenance of the radiation source target track invalid.By incorporating the elevation information of the passive sensor into the automatic bearings-only tracking(BOT)and consolidating these uncertainties under the framework of random finite set(RFS),a novel approach for tracking maritime radiation source target with intermittent measurement was proposed.Under the RFS framework,the target state was represented as a set that can take on either an empty set or a singleton; meanwhile,the measurement uncertainty was modeled as a Bernoulli random finite set.Moreover,the elevation information of the sensor platform was introduced to ensure observability of passive measurements and obtain the unique target localization.Simulation experiments verify the validity of the proposed approach for tracking maritime radiation source and demonstrate the superiority of the proposed approach in comparison with the traditional integrated probabilistic data association(IPDA)method.The tracking performance under different conditions,particularly involving different existence probabilities and different appearance durations of the target,indicates that the method to solve our problem is robust and effective.

扫描开关检测方法探讨

介绍了扫描开关的主要用途,对扫描开关的检测项目、检测仪器和检测方法进行讨论,重点说明所采用检测方法的原理,给出了扫描开关的检测数据,并分析了扫描开关检测结果不确定度。

Comparison of GUF and Monte Carlo methods to evaluate task-specific uncertainty in laser tracker measurement

Measurement uncertainty plays an important role in laser tracking measurement analyses. In the present work, the guides to the expression of uncertainty in measurement(GUM) uncertainty framework(GUF) and its supplement, the Monte Carlo method, were used to estimate the uncertainty of task-specific laser tracker measurements. First, the sources of error in laser tracker measurement were analyzed in detail, including instruments, measuring network fusion, measurement strategies, measurement process factors(such as the operator), measurement environment, and task-specific data processing. Second, the GUM and Monte Carlo methods and their application to laser tracker measurement were presented. Finally, a case study involving the uncertainty estimation of a cylindricity measurement process using the GUF and Monte Carlo methods was illustrated. The expanded uncertainty results(at 95% confidence levels) obtained with the Monte Carlo method are 0.069 mm(least-squares criterion) and 0.062 mm(minimum zone criterion), respectively, while with the GUM uncertainty framework, none but the result of least-squares criterion can be got, which is 0.071 mm. Thus, the GUM uncertainty framework slightly underestimates the overall uncertainty by 10%. The results demonstrate that the two methods have different characteristics in task-specific uncertainty evaluations of laser tracker measurements. The results indicate that the Monte Carlo method is a practical tool for applying the principle of propagation of distributions and does not depend on the assumptions and limitations required by the law of propagation of uncertainties(GUF). These features of the Monte Carlo method reduce the risk of an unreliable measurement of uncertainty estimation, particularly in cases of complicated measurement models, without the need to evaluate partial derivatives. In addition, the impact of sampling strategy and evaluation method on the uncertainty of the measurement results can also be taken into account with Monte Carlo method, which plays a guiding role in measurement planning.

Automated dual source systems for measurement of DC resistance standards

A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratories without cryogenic current comparators(CCC)or direct current comparators(DCC)bridges.Behavior of this bridge is evaluated by comparing its measured values with the unknown resistor values obtained by another method.The accuracy of the introduced bridge is in the level of 10-5 for the 1 mΩresistor,and in the level of 10-4 for the 10 mΩ,100 mΩand 1Ωresistors.Moreover,a dual voltage sources system for the measurement of DC standard resistors from 1 kΩto 100 MΩis also presented.In this system,a modification is made on the modified Wheatstone bridge to evaluate its performance by adding another digital multimeter to measure the ratio between the unknown and the standard resistors simultaneously.This bridge is verified by comparing the measured values of 10 kΩresistor obtained by the two methods with its actual value.The bridge accuracy is in the level of 10-6 except for the 1 kΩresistor,and the bridge asymmetry is also evaluated.It is found the asymmetry is in the level of 10-6 for the resistors from 10 kΩto 100 MΩand in the level of 10-5 for 1 kΩresistors.The introduced bridges operations are controlled by LabVIEW programs designed specially for this purpose,and the expanded uncertainty is also evaluated for all measurement results.

High-precision inductance measurement system based on double-excitation auto-balancing bridge

In order to achieve high precision measurement of inductance in a wide frequency range,a method of inductance measurement based on double-excitation auto-balancing bridge is proposed.In this method,the direct digital synthesizer(DDS)as signal generator is used as the bridge excitation source,and the bridge is automatically balanced by adjusting and measuring the voltage ratio.Using standard resistors,the system can achieve high precision measurement of four-terminal pair inductors in the frequency range of 100Hz-100kHz.Aiming at the low efficiency of bridge balancing,an iterative balancing algorithm based on the steepest descent method is proposed.In order to suppress the interference caused by the initial phase change and non-integer periodic sampling,the high-precision measurement of the complex impedance of inductance is realized based on the all-phase fast Fourier transform(apFFT).Finally,the corresponding measurement system is built and the inductance measurement experiment is carried out.The experimental results show that the relative error of the system for inductance measurement can be as low as 0.009%,and the optimal relative measurement uncertainty of the system can reach 9.89×10^(-4)compared with 5×10^(-5)of commercial impedance analyzer.

Uncertainty Calculation of Roundness Assessment by Automatic Differentiation in Coordinate Metrology

Reomtly, Coordinate bieasuring Machines （CMMs） are widely used to measure roundness errors. Roundness is calculated from a large number of points collected from the profiles of the parts. According to the Guide to the Expression of Uncertainty in Measta- meat （GUM）, all measurement results must have a stated uncertainty associated the titan. However, no CMMs give the uncertainty value of the roundness, because no suitable measrement uncertainty calculation procedure exists. In the case of roundness raeasurement in coordinate metrology, this paper suggests the algorithms for the calculation of the measurement uncertainty of the roudness deviation based on the two mainly used association criteria, LSC and MZC. The calculation of the sensitivity coefficients for the uncertainty calculatiion can be done by autnatic differentiation, in order to avoid introducing additional emars by the traditional difference quotient approxima- tions. The proposed methods are exact and need input data only as the nrasured coordinates of the data points and their associated un- certainties.

Calculation of Measurement Uncertainty for Stiffness Modulus of Asphalt Mixture

Asphalt mixture is a highly heterogeneous material, which is one of the reasons for high measurements uncertainty when subjected to tests. The results of such tests are often unreliable, which may lead to making bad professional judgments. They can be avoided by carrying out reliable analyses of measurement uncertainty adequate for the research methods used and conducted before the actual research is done. This paper presents the calculation of measurements uncertainty using as an example--the determination of the stiffness modulus of the asphalt mixture, which, in turn, was accomplished using the indirect tension method. The paper also shows the employment of the basic methods of statistical analysis, such as testing two mean values and conformity tests. Essential concepts in measurements uncertainty have been compiled and the determination of the stiffness module parameters are discussed. It has been demonstrated that the biggest source of error in the stiffness modulus measuring process is the displacement measure. The aim of the research was to find the measurement uncertainty for stiffness modulus by an indirect tensile test and the presentation of examples of the used statistical methods.

An Accuracy Improvement for the Clinical Test Result by United ISO-GUM and QE

This research developed the technology which united ISO-GUM （International Organization of Standard-Guide to Express of Uncertainty in Measurement） and QE （Quality Engineer） strategically and employed both feature efficiently. Although to tow technology of purpose use is same, each has future. The purpose is scheduled to improve the accuracy as a result of the clinical examinations. The result of research was used for diagnosis by equivalent Quality Control （eqQC） of the same level when and where, that are needed for broader-based medical system of the time of IT-era. Since National Institute of Standard and Technology （NIST） is recommend use of complicated operation by ISO-GUM for uniting, realization required the newest high quality computer technology. The algorithm of the complexity system of operation is that Fast Fourier Transform （FFT）, Inverse Fast Fourier Transform （IFFT） and Multi-variance Analysis （MA） are needed in Fig. 4. The main new improving points are changed of ambiguous expression method of data, and the pursuit which the cause of worsens accuracy put into data. All data with an assurance reported the final result for patient or donor. Medical laboratory quality system service is offered essential in the laboratory to be correct result for health care by Good Laboratory Practices （GLP） useful ISO 15189. Quality Assurance （QA） is achieved though system reliability.

Study of Stability of Saturated Salt Solutions Cells

This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. The study was carried out using three saturated salt solutions, which are Potassium Acetate 22.5%, Potassium Iodide 68.9% and Potassium Sulphate 97.3% to cover low, medium and high relative humidity. The study was carried out using different shapes and volumes half liter spherical, liter spherical and liter conical per each salt which was prepared. The apparatus which used in measurement system in the first time are the same which used after ten years. The results show that the change of relative humidity value after ten years ranged from 0.1% to 0.7%. This value is suitable within uncertainty ＋ 2%. The period of stability for each run for all cells was found to be more than five hours and this period enough for calibration. The measurements show that the cells are stable for more than ten years with accepted value.

Development of NIS Two-Temperature Humidity Generator

Abstract： This paper describes the development and characterization of a two-temperature （2-T）, constant pressure humidity generator It relies on the saturation of a stream of gas flowing over a water surface maintained at constant, well-known, temperature. It was built in order to improve the uncertainties of the dew-point temperature and humidity scales realization at the National Institute for Standard （NIS） in the dew-point range from -50 ℃ to ＋ 10 ℃. Several experiments were carried out in the above mentioned range in order to characterize the generator. Characterization comprised studies of its saturator efficiency, temperature stability and a comparison with a calibrated chilled-mirror hygrometer. The results of the efficiency tests showed good performance of the generator as described below. For uncertainty of measurements, a thorough analysis was also described representing estimations of contributions for all the sources that affecting measurements.

Theoretical analysis and verification of uncertainty of measurement on a cantilever coordinate measuring machine

A cantilever coordinate measuring machine(CCMM)is proposed according to the in-situ measurement requirement of workpieces with complex structures limited by the finite space of the5-axes computerized numerical control(CNC)processing site.Factors affecting uncertainty of measurement(UM)are classified and analyzed on the basis of uncertainty evaluation criteria,and the estimation technique of UM for measuring systems is presented.UM of the CCMM is estimated from the factors such as temperature,error motions as well as the mechanism deformations.Measurement results show that the actual measurement error is smaller than that of measurement requirement.

Some Peculiarities of the Preprocessing of Spectral Data and Images

Remotely sensed spectral data and images are acquired under significant additional effects accompanying their major formation process, which greatly determine measurement accuracy. In order to be used in subsequent quantitative analysis and assessment, this data should be subject to preliminary processing aiming to improve its accuracy and credibility. The paper considers some major problems related with preliminary processing of remotely sensed spectral data and images. The major factors are analyzed, which affect the occurrence of data noise or uncertainties and the methods for reduction or removal thereof. Assessment is made of the extent to which available equipment and technologies may help reduce measurement errors.

Uncertainty Estimation for the Determination of Trace Heavy Metals in Human Hair by Flame and Electrothermal Atomic Absorption Spectrometry

Trace element analysis on hair samples has been widely used to assess wildlife and human exposure to different contaminants present in the environment or at the workplace. Pollutants due to the presence of toxic metals in environment not only enter the body by breading, water, and foodstuff accumulates in hair, but they could be adsorbed directly on the hair from environment. In order to remove adsorbed elements and thus determine the internally bound elements correctly, hair sample must be washed. In the present work, we propose uncertainty estimation for the analytical results that are obtained from determination of cadmium, lead, copper, iron, manganese and nickel in human hair by flame and electrothermal atomic absorption spectrometry （FAAS and ETAAS）. To estimate the uncertainty of analytical result obtained, two types of bias are calculated in the assessment of trueness： a proportional bias and a constant bias. Nested design was applied for calculating proportional bias and Youden method to calculate the constant bias. The results we obtained for proportional bias are calculated from spiked samples. In this case, the concentration found is plotted against the concentration added and the slop of standard addition curve is an estimate of the method recovery. Estimated method of average recovery in human hair is： （1.019 ±0.026）, （0.918 ±0.014）, （1.073±0.016）, （1.0597± 0.017）, （1.073± 0.020） and （0.934± 0.117） for Cd, Pb, Mn, Ni, Fe and Cu respectively.

Measurement of the lifetimes of promptly produced Ω_(c)^(0) and Ξ_(c)^(0) baryons

A measurement of the lifetimes of theΩ_(c)^(0)andΞ_(c)^(0)baryons is reported using proton-proton collision data at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.4 fb;collected by the LHCb experiment.TheΩ_(c)^(0)andΞ_(c)^(0)baryons are produced directly from proton interactions and reconstructed in the p K^(-)K^(+)π^(+)nal state.TheΩ_(c)^(0)lifetime is measured to be 276.5±13.4±4.4±0.7 fs,and theΞ_(c)^(0)lifetime is measured to be 148.0±2.3±2.2±0.2 fs,where the first uncertainty is statistical,the second systematic,and the third due to the uncertainty on the D^(0)lifetime.These results con firm previous LHCb measurements based on semileptonic beauty-hadron decays,which disagree with earlier results of a four times shorterΩ_(c)^(0)lifetime,and provide the single most precise measurement of theΩ_(c)^(0)lifetime.

Characterization of a Powertrain Test Bed in the Context of Virtual Validation of Drivability

Technological trends in the automotive industry toward a software-defined and autonomous vehicle require a reassessment of today’s vehicle development process.The validation process soaringly shapes after starting with hardware-in-the-loop testing of control units and reproducing real-world maneuvers and physical interaction chains.Here,the road-to-rig approach offers a vast potential to reduce validation time and costs significantly.The present research study investigates the maneuver reproduction of drivability phenomena at a powertrain test bed.Although drivability phenomena occur in the frequency range of most up to 30∙Hz,the design and characteristics substantially impact the test setup’s validity.By utilization of modal analysis,the influence of the test bed on the mechanical characteristic is shown.Furthermore,the sensitivity of the natural modes of each component,from either specimen or test bed site,is determined.In contrast,the uncertainty of the deployed measurement equipment also affects the validity.Instead of an accuracy class indication,we apply the ISO/IEC Guide 98 to the measurement equipment and the test bed setup to increase the fidelity of the validation task.In conclusion,the present paper contributes to a traceable validity determination of the road-to-rig approach by providing objective metrics and methods.

Evaluation of measurement uncertainty based on grey system theory for small samples from an unknown distribution

To evaluate measurement uncertainty for small sample size and measurement data from an unknown distribution, we propose a grey evaluation method of measurement uncertainty based on the grey relation coefficient. The uncertainty of measurement is analyzed using grey system theory, and the defects of the grey evaluation model of measurement uncertainty (GEMU) are studied. We then establish an improved grey evaluation model of measurement uncertainty (IGEMU). Simulations show that the precision of IGEMU is greater than that of GEMU, and that sample size has only a small effect on the precision of IGEVU. In particular, IGEMU is applied to evaluating measurement uncertainty for small sample size and measurement data from an unknown distribution. The measurement uncertainty of total profile deviation, which is measured by the CNC gear measuring center, can be evaluated by a combination of IGEMU and the Monte Carlo method.