Calibration of On-Board Energy Measurement Systems Installed in Locomotives for AC Distorted Current and High Voltage Waveforms and Determination of Its Uncertainty Budget

Periodic calibrations of Energy Measurement Systems (EMS) installed in locomotives must be carried out to demonstrate the required accuracy established in the EN 50463-2 standard according to European Parliament and Council Directive 2008/57/EC on the interoperability of rail systems within the Community. As a result of the work performed in the “MyRailS” EURAMET project an AC calibration facility was developed consisting of a fictive power source was developed. This fictive power source can generate distorted sinusoidal voltages up to 25 kV-50 Hz and 15 kV-16.7 Hz as well as distorted sinusoidal currents up to 500 A with harmonic content up to 5 kHz or phase-fired current waveform stated in EN50463-2 standard. These waveforms are representative of those that appear during periods of acceleration and breaking of the train. Reference measuring systems have been designed and built consisting of high voltage and high current transducers adapted to multimeters, which function as digital recorders to acquire synchronized voltage and current signals. An approved procedure has been developed and an in-depth uncertainty analysis has been performed to achieve a set of uncertainty formulas considering the influence parameters. Different influence parameters have been analyzed to evaluate uncertainty contributions for each quantity to be measured: rms voltage, rms current, active power, apparent power and non-active power of distorted voltage and current waveforms. The resulting calculated global expanded uncertainty for the developed Energy Measuring Function calibration set up has been better than 0.5% for distorted waveforms. This paper is focused on presenting the complete set of expressions and formulas developed for the different influence parameters, necessary for uncertainty budget calculation of an Energy Measuring Function calibration.

Electrical Harmonic Energy Measurement Based on Wavelet Packet Decomposition and Reconstruction Algorithm

In order to study the accurate measurement of electric energy in complex industrial field, a method of harmonic electric energy measurement based on wavelet packet decomposition and reconstruction algorithm, as well as the calculation formula of harmonic power and the principle of harmonic electric energy measurement are proposed. Using db42 wavelet function to carry out harmonic energy metering simulation analysis, the results show that: The fundamental frequency of the simulation signal is 50 Hz, two-layer wavelet packet transform is adopted, the simulation input signals within 40 fundamental wave cycles are taken, and the sampling frequency fs is 800 Hz. Conclusion: The three-phase harmonic energy metering device based on virtual instrument technology has realized the measurement of each harmonic active power and reactive power, and the accuracy reaches 0.2 s.

Quantitative Aspects of Computed Tomography

<p>Computed tomographic (C.T.) images are stored digitally as arrays of C.T. numbers, the elements of which are strongly related to the linear X-ray attenuation coefficients of the corresponding tissue volumes in the patient. This thesis is concerned with this quantitative information. Relating measured C.T. numbers to the properties of materials requires the ability to compute attenuation coefficients from compositions and densities. Numerical techniques have been used in the present work to produce formulae which are much simpler and more accurate than those currently used. Dual energy computed tomography permits the computation of parameters such as tissue densities and effective atomic numbers which may have more clinical relevance than the attenuation coefficient. A dual energy capability has been developed for the Wellington Hospital G.E. 8800 scanner. A simple algorithm has been developed for computing electron densities from dual energy C.T. scans. A spine mineral measurement procedure has been developed for the 8800 scanner which reports both single and dual energy bone measurements. A computationally efficient algorithm has been derived for the calculation of true mineral concentration and cancellous tissue density from dual energy C.T. measurements. Measurements on 31 volunteers compare well with published normal ranges for single energy C.T. Both single energy C.T. spine mineral densitometry and dual photon absorptiometry are prone to errors due to variable fat content, leading to ambiguity in interpreting the results of measurements on patients with anorexia nervosa. Measurements on 68 anorexic patients gave an average single energy value 18 % lower than that for the volunteers. The average mineral concentration determined from dual energy measurements was 19% lower, confirming that there is a genuine loss of mineral. Neither the single or dual energy mineral measurements showed any protective effect from the use of estrogen contraceptive pills, but both measurements correlated positively with the level of exercise at the time of examination, and with the duration of high calcium intake during adolescence. The dual energy mineral measurement showed no significant improvement in patients who had recovered from anorexia nervosa. Differences in image texture seen in C.T. images of the vertebral body reflect differences in the gross structure of the cancellous bone tissue. An in vivo study on vertebrae from 9 sheep was not useful in correlating the C.T. appearances of the cancellous tissue with scanning electron microscope (SEM) images of the same tissue because the characteristic appearances noted in humans were not present in the sheep specimens. However correlations between C.T. measurements of sheep vertebrae and trabecular bone volumes determined from SEM images of the same sections give linear regression correlation coefficients of 0.87 for the single energy measurement and 0.81 for the dual energy measurement. A study using human tissue is under way, but insufficient specimens had become available at the time of writing to be reported in detail here.</p>

Quantitative Aspects of Computed Tomography

<p>Computed tomographic (C.T.) images are stored digitally as arrays of C.T. numbers, the elements of which are strongly related to the linear X-ray attenuation coefficients of the corresponding tissue volumes in the patient. This thesis is concerned with this quantitative information. Relating measured C.T. numbers to the properties of materials requires the ability to compute attenuation coefficients from compositions and densities. Numerical techniques have been used in the present work to produce formulae which are much simpler and more accurate than those currently used. Dual energy computed tomography permits the computation of parameters such as tissue densities and effective atomic numbers which may have more clinical relevance than the attenuation coefficient. A dual energy capability has been developed for the Wellington Hospital G.E. 8800 scanner. A simple algorithm has been developed for computing electron densities from dual energy C.T. scans. A spine mineral measurement procedure has been developed for the 8800 scanner which reports both single and dual energy bone measurements. A computationally efficient algorithm has been derived for the calculation of true mineral concentration and cancellous tissue density from dual energy C.T. measurements. Measurements on 31 volunteers compare well with published normal ranges for single energy C.T. Both single energy C.T. spine mineral densitometry and dual photon absorptiometry are prone to errors due to variable fat content, leading to ambiguity in interpreting the results of measurements on patients with anorexia nervosa. Measurements on 68 anorexic patients gave an average single energy value 18 % lower than that for the volunteers. The average mineral concentration determined from dual energy measurements was 19% lower, confirming that there is a genuine loss of mineral. Neither the single or dual energy mineral measurements showed any protective effect from the use of estrogen contraceptive pills, but both measurements correlated positively with the level of exercise at the time of examination, and with the duration of high calcium intake during adolescence. The dual energy mineral measurement showed no significant improvement in patients who had recovered from anorexia nervosa. Differences in image texture seen in C.T. images of the vertebral body reflect differences in the gross structure of the cancellous bone tissue. An in vivo study on vertebrae from 9 sheep was not useful in correlating the C.T. appearances of the cancellous tissue with scanning electron microscope (SEM) images of the same tissue because the characteristic appearances noted in humans were not present in the sheep specimens. However correlations between C.T. measurements of sheep vertebrae and trabecular bone volumes determined from SEM images of the same sections give linear regression correlation coefficients of 0.87 for the single energy measurement and 0.81 for the dual energy measurement. A study using human tissue is under way, but insufficient specimens had become available at the time of writing to be reported in detail here.</p>

Research Progress on Calculation and Control of Unaccounted for Gas of Natural Gas Pipeline Network

At present, volume measurement is still used in transfer measurement of natural gas in China, so the calculation and management of Unaccounted for Gas are based on volume measurement. With the change of natural gas measurement method from volume measurement to energy measurement, the calculation and management of Unaccounted for Gas based on energy measurement will be paid more and more attention. This paper investigates the calculation methods and management measures of Unaccounted for Gas based on volume measurement in China and Unaccounted for Gas based on energy measurement in other countries, and compares the research progress. The results show that: the general principles of Unaccounted for Gas calculation in China and other countries are basically the same, but the calculation formulas are not completely the same. All countries consider the input gas, output gas, line pack variation and self-consumption gas. On this basis, Italy considers the known leakage, and Britain considers the known leakage and the daily calorific value shrinkage caused by its settlement rules. In order to reduce Unaccounted for Gas, the UK regularly verifies meter, carries out the research on Unaccounted for Gas baseline, and actively participates in the global Unaccounted for Gas benchmarking. Australia replaces the old main line and reduces the operation pressure of pipeline, which significantly reduces Unaccounted for Gas. The calculation methods and control measures of Unaccounted for Gas based on energy measurement in Italy, Britain and Australia can be used for reference in China.