## IMEKO Event Proceedings

Page 2 of 812 Results 11 - 20 of 8114

**1 %Omega;–10 k%Omega; High Precision Resistance Setup to calibrate Multifunction Electrical instruments**

A temperature controlled 1 %Omega;–10 k%Omega; Standard resistors setup was developed at National Institute of Metrological Research, (INRIM). The aim of this realization was the involvement of the setup resistors in the traceability transfer process to high accuracy multifunction electrical instruments used in Secondary Electrical Calibration Laboratories or even their use as primary Standards in high level Laboratories or Institutes. The 1 %Omega;–10 k%Omega; Standards are formed respectively by two 10 %Omega; and 100 k%Omega; parallel connected resistors nets inserted in a temperature controlled aluminium box. Construction details, temperature and power coefficients, stability data and preliminary mid-term use uncertainty budgets of the two setup Standards are given. Their first short time (2 h) stability were on the order of few parts of 10–8. A test to calibrate a multifunction calibrator gave satisfactory results.

**1 MHZ MODULE TRANSFORMER BRIDGE**

A transformer bridge to study low-loss dielectrics at the frequency 1 MHz is developed. The main components of the bridge: a ratio transformer and variable measuring standards of capacitance and conductance are made in the form of removable modules. The bridge measurement range by loss angle tangent *D* is 10^{-6} - 10^{-3} with the capacitance 1-1000 pF. Measurement uncertainty *D* is ± (2-3) &itimes; 10^{-6}, *k* = 2.

**10 MN BUILD-UP FORCE STANDARD MACHINE DEVELOPED IN CHINA**

The paper describes a 10 MN Build-up force standard machine developed in China. The BM has capacity of 10 MN compression, relative expanded uncertainty of 0.05% (*k* = 2, probability being about 95%) which has been evaluated based on characteristics of three load cells as reference as well as on force comparison with 20 MN hydraulic amplification force standard machine established at NIM being relative expanded uncertainty of 0.01% (*k* = 3), force fluctuation of less than ±0.002%,etc. The BM is driven by a hydraulic system with a technology patented in China, which makes loading speed quicker and much stable as well as unloading. The force measuring system is similar to the other BM such as 9 MN BM established by LNE/France, and one by INRIM/Italy, etc.

**100 N·m NEGATIVE STEP DYNAMIC TORQUE STANDARD MACHINE**

100 N·m negative step dynamic torque standard machine is used to calibrate the dynamic characteristics of torque transducer. Through measurement of negative step excitation time *τ*,it can get the inherent frequency *ω*_{n}. The paper describes the working principle, key technology, test data and the uncertainty analysis of the machine. The specification of machine is as follows: measurement range 100 N·m, *τ* ≤ 5ms, uncertainty *U* = 2.64%, *k*=2.

**2 TERMINAL DUAL SOURCE IMPEDANCE BRDIGE**

Two terminal dual source low frequency impedance bridge was configured using commercial voltage calibrators. The bridge performance was evaluated by measuring 1 to 1 resistance ratio at 1 kHz using 1 kΩ and 10 kΩ resistors. The AC resistance ratio was also measured at frequencies from 100 Hz to 100 kHz. The same bridge was used for measuring ratios of other impedance combinations by adjusting the phase between the voltage sources. This simple two terminal dual source impedance bridge proved its reliable and versatile measurement capability.

**2.5 V, 10-bit, 50-MS/s CMOS Pipeline Low Power A/D Converter**

In this paper, we present A/D converter for signal processing of infrared sensor and CMOS image sensor. The A/D converter implemented in a 0.25 um CMOS process provides a resolution of 10bits at a sampling rate of 50 MS/s while dissipating 67 mW from 2.5 V supply voltage.

This A/D converter is based on a pipelined architecture in which the number of bits converted per stage and the stage number are optimized to simultaneously achieve the desired linearity and reduce power consumption as well. Simulation results show that the A/D converter using 1.5 bit per stage MDAC with switched capacitors and dynamic comparators efficiently reduces the power consumption.

**25 kN·m TORQUE CALIBRATION MACHINE REACHES**

*U*_bmc = 0.008% USING NEW DESIGN FEATURESDue to the need to calibrate high-precision torque transducers also for production purposes, a suitable torque reference standard had to be built up. Using new design features and qualifying the calibration machine by self-contained measurements and advanced measurement uncertainty calculations, resulted in a best measurement capability of *U*_{bmc} = 0.008%.

**2D AND 3D APPROACH TO MEASURING ROUGHNESS PARAMETERS**

Contrary to the previous requirement to only monitor the changes, the need to understand the nature of the surface structure is more and more emphasised nowadays. There is already the possibility for 3D measurements, to a great extent owing to the development of electronics and computers. The contribution of this paper is in the analysis of the assessment of roughness using classical roughness parameters applied to 3D surfaces and an attempt to define the new parameters that would provide a more complete assessment of roughness with relation to the functional requirements met by the surface.

**2D and 3D numerical simulation results of vortex flowmeter under nonideal installation conditions**

An air test line of 50mm diameter was used in experiments covering two kinds of straight pipe length, and the numerical simulation results of vortex shedding frequency, which originated from the ANSYS FLUENT analysis results, were proved to be highly consistent with the experimental results. Based on this comparison, flow field simulation studies, including 13 pipe conditions, were carried out to establish the effect of upstream and downstream elbow fittings on the performance of the vortex flowmeter. The results indicated that the influences of the upstream straight pipe length were more obvious than the downstream straight pipe length. When there was an upstream elbow, the frequency value was greatly reduced, and the maximum error was -60.62%. The closer the elbow was to the vortex generator, the larger the decrease. The downstream elbows had a relatively small influence on the measurement results, and the maximum error was -13.23%. Considering the asymmetry of the 2D pipeline, the 3D simulations of part of the pipeline condition were further executed. The differences between 2D and 3D calculation results were analyzed, and the application value of different simulation results was explored.

**2D MEASUREMENTS OF PRIMARY SOOT DIAMETER IN DIFFUSION FLAMES BY TWO-DIMENSIONAL TIME RESOLVED LASER INDUCED INCANDESCENCE (2D TIRE-LII)**

Two dimensions primary soot diameter calculation in a laminar diffusion LPG flame by means of Laser Induced Incandescence (LII) is presented in present paper. LII is a high sensitive technique in which a high energy Nd-YAG laser sheet heats soot particles to a temperature of about 4000 K but without exceeding the sublimation temperature. Radiation from exited soot particles is acquired by means of an intensified CCD camera (low gate opening time of 10ns) synchronized with the laser pulse. By delaying the acquisition time with respect to laser pulse, LII signal decay as function of time has been reconstructed. Performing acquisition at two different wavelengths by means of two interferometric filters (Two color LII) a soot temperature behaviour (related to particles primary diameter) has been calculated. Using a self calibration method for optics and laser fluence and selfabsorption corrections for LII signal, bi dimensional quantitative measurements can be achieved for soot dimensions and distribution. Thanks to a center- of-mass alignment of flame within corrected images at different time steps, it is possible to achieve the soot decay curve for each pixel of images, thus obtaining two dimensional soot primary particles visualization.

Page 2 of 812 Results 11 - 20 of 8114