David Kimetto
THE USE OF STRAIN GAUGES IN THE KENYAN INDUSTRY FOR MEASUREMENT

The rapid development of micro-electronics has produced an increasing demand for small sensors offering high quality performance. Strain gauges are an important aid in all areas of experimental stress analysis, for determining the strain on the surface of components. In addition, the uses of strain gauges in the manufacture of transducers for measuring mechanical quantities has proven to be extremely reliable technology, giving excellent results.

Sergiej Taranow, Andrzej Olencki, Yuri Tesik
THE USE OF TEST SIGNAL FOR MINIMIZATION OF PULSE AND WIDE BAND AMPLIFIERS MULTIPLICATION ERROR

Pulse amplifiers are widely used in radio engineering. The first requirement to these amplifiers is to provide minimal distortion of rectangular pulse shape. The second is provision minimal multiplication error, which is important for measurements. The standard method, grounded on the usage of negative feedback, may be used for wide band periodical signals and unacceptable for amplification pulse signals due to a signal delete in the forward and backward branches. It is proposed to use for this problem solution, borrowed from cybernetic engineering, the adaptive method with small test signal for calibration. The paper illustrates the mechanism of acting, dynamic and static analysis, based on proposed the Method of Linearization by the Describing Functions.

Henk Jan Panneman, Cornelis W. Koreman, Sjoerd Toonstra, Floris Huijsmans
THE USE OF ULTRASONIC GAS FLOW METERING TECHNOLOGY FOR THE DEVELOPMENT OF ACCURATE ENERGY METERS FOR NATURAL GAS

Gasunie Research gained their years of experience in efficient energy utilization, gas transport and gas measurement as the in-house laboratory for N.V. Nederlandse Gasunie. This company, which was an integrated gas transport and trading company until the beginning of 2002, has been one of the largest gas suppliers in Europe for several decades. As part of this company, Gasunie Research has always striven to guarantee the continuity of the gas supply, to ensure the safety of gas transport and to enhance the added value of natural gas as a fuel. Gasunie Research developed a wealth of new technology for domestic, commercial and industrial end users, and for the energy sector itself. The expertise that Gasunie Research has acquired through these activities and the years of practical experience is now made available to third parties.
Energy measurement is one of the main tasks of gas transport companies. New challenges in the gas world confront gas transport companies with new requirements regarding energy measurement. (e.g. the variation in gas composition will be larger and will occur more frequently). These changes are the driving force for a number of new developments in energy metering. Present energy measurement systems for natural gas comprise of volume metering, volume conversion from field conditions to reference conditions and calorific value determination at reference conditions. The calorific value, H_SR , is mostly determined by compositional assay using a process gas chromatograph. The volume is commonly measured by a turbine flow meter, an ultrasonic flow meter or an orifice plate. The volume conversion factor is mostly determined from thermal equations of state, using the gas composition or some gas properties as input. The cost of ownership for accurate energy meters based on process gas chromatographs is high. These high costs were the main reason for Gastransport Services (the transportation company of N.V. Nederlandse Gasunie) and Ruhrgas AG to join forces on the development of new energy flow measurement methods.
These new methods are based on the measurement of three suitable properties (e.g. physical properties or component concentrations) and an accurate correlation between these properties and the gas composition. The inferred gas composition is used to compute a variety of gas properties like the superior calorific value, the density, the compression factor under reference and field conditions and the Wobbe-Index.
Within the joint project Gasunie Research focussed on the development of an energy meter based on velocity of sound measurements. The new meter is based on the measurement of the velocity of sound at high pressure (VOS_high), the velocity of sound at low pressure (VOS_low), and the molar fraction carbon dioxide (X_CO2). This combination is particularly suitable for stations with high pressure gas available (P > 40 bar).
In this paper results for the superior calorific value of natural gas obtained with both a dedicated double velocity of sound meter and with velocity of sound measurements obtained by an ultrasonic gas flow meter will be discussed.

Stuart Davidson
THE USE OF X-RAY PHOTOELECTRON SPECTROSCOPY TO ESTIMATE THE STABILITY OF PRIMARY MASS STANDARDS

Because it is still defined in terms of an artefact, the limit on the accuracy with which the SI unit of mass can be realised is largely limited by the surface stability of the kilogram standard. Not only is this true on the case of the International Prototype used to define the unit but also for national standard copies and indeed for mass standards in general. This paper describes the use of x-ray photoelectron spectroscopy (XPS) to study the accretion of contamination of the surfaces of standard masses. Angle resolved X-ray photoelectron spectroscopy (AR XPS) was used to characterise the surfaces of platinum-iridium and stainless steel mass standards stored either in air or in vacuum, or which have been transferred between the two media. Various analysis methods for XPS data have been compared both in terms of providing an overlayer thickness on the mass standard and in terms of analysing the composition of this layer of contamination.

Mladen Banovic, Zdenko Godec, Vilko Cindric
THE VALUE OF INFORMATION OBTAINED THROUGH TRANSFORMER MONITORING SYSTEM

Transformer reliability and availability are keys to a profitable process of power generation and transmission. On-line supervision of transformers improves their reliability, positively influencing correct and safe functioning of the whole power system. To achieve the desired transformer availability, the user should have information about the transformer state and operating conditions. Especially, he should have information about incipient faults before they escalate into failures. A transformer monitoring system with ability to supervise all the significant transformer parameters is the proper way to obtain valuable information, and on the basis of trustworthy information to achieve the desired reliability and availability, personnel and environment safety.
Diagnostics combined with monitoring information results in better diagnostic decisions and recommendations.
Information obtained through monitoring system enables also transformer producers to improve and optimize the design and the production process on the basis of real-time operating parameters, what results in better features of transformers.
The insurance companies scale insurance premium for equipment insurance according to the state of equipment, frequency of failures and other information based on risk evaluation. The monitoring system information could provide data for evaluation of the transformer state and prediction of possible failures, what is important for insurance.