A theoretical and numerical analysis of the measured equation ofinvariance

The measured equation of invariance (MEI) has been previously introduced to efficiently and accurately handle the boundary truncation for finite methods. The present authors give a theoretical analysis that provides several important insights into the capabilities of the MEI. From the numerical study, they can explain why the MEI works better than one would expect. Both the theoretical and the numerical analyses demonstrate that the accuracy of the solution is dependent on the electrical size of the geometry as well as the distance between the mesh boundary and the geometry. From the analysis, the authors propose a new set of metrons that is less sensitive to the excitation than the previously proposed sinusoidal metrons     

The method of testing of XLPE cable insulation resistance to partial discharges and electrical treeing

The paper gives a method of model XLPE medium voltage cable insulation testing for partial discharges and electrical treeing with a point to plane test geometry. Based on this method, a comparative estimate of insulation resistance to treeing and partial discharges have been made. XLPE crosslinked by different methods (steam medium and hot nitrogen medium) and with varying contents of inorganic filler kaolin were tested. The characteristics of partial discharges were measured by means of a pulse height analyser characterized with a microscope. The data have been analysed statistically.     

An investigation of the usability of image-based CAPTCHAs using PROMETHEE-GAIA method

Multimedia Tools and Applications - Today, it is difficult to find an adequate Web site with a registration form that is not protected with some automated human proof test. One of the oldest...     

Impact of bias condition on 1/f noise of dual-gate depletion type MOSFET in linear region and consequences for noise diagnostic application and modelling

This paper presents experimental and numerical results for 1/f noise of depletion-type dual-gate MOSFET (DGMOSFET) in the linear region of the output I_D-V_DS characteristics. In this region, both DGMOSFET inner transistors operate in either linear or non-linear region each. Gate-to-gate interelectrode spacing influence is taken into account in I_D-V_DS modelling with the effective parameter m_eff = μ_eff2L_eff1/μ_eff1L_eff2. For low bias conditions, the parameter m_eff can be reduced to the ratio of inner transistors channel effective lengths. A model for the normalized 1/f noise parameter and methodology for its calculation valid for the DGMOSFET linear region have been proposed. Due to interdependence of the inner transistors bias condition, their participation in total noise is controlled by weighting factors. This fact must be taken into account in the noise diagnostic procedure for DGMOSFET analysis.     

A versatile, PC-based gamma ray monitor

This paper describes a new computer-based gamma ray monitor for laboratory and field measurements. The monitor consists of a universal peripheral device, and GM counter gamma ray probe, connected via USB to the PC. The peripheral device is generic; in addition to the GM probe, it accepts sensors for spectrometric measurements as well as sensors for the measurement of other environmental parameters. Owing to its low-power consumption, it is used with laptop or palmtop computer, as a portable field measurement instrument. The proposed solution has advantages over conventional instrument: (1) open architecture; (2) user-defined functions and (3) easy network connection.     

Engine oil contribution to diesel exhaust emissions

The reduction of harmful pollutant emissions as well as CO₂ emissions emanating from motor vehicles will be of considerable interest in the coming decades. Emissions legislation will be the guiding principle in the development of new technologies and vehicles. More attention will have to be paid to off‐road vehicles, especially tractors, if the production of healthy food and the maintenance of a cleaner environment are not to be compromised. Therefore, one the biggest challenges facing the automotive industry is to improve fuel economy, both to conserve natural resources and to limit pollutants and CO₂ emissions. Better fuel efficiency and consequently lower emissions will require new materials, new lubricants and low‐emission fuel. Engine lubricants help to improve vehicle efficiency but contribute engine exhaust emissions. This paper deals with the influence of engine lubricants on diesel exhaust emissions. Investigations have shown a clear effect of lubricant oil on emissions, which depends on lube oil characteristics, especially sulfur content, metal content, volatility and density. Copyright © 2006 John Wiley & Sons, Ltd.     

PD tests to measure the electrical treeing resistance of cableinsulation and erosion rate resistance of capacitor metalized films

The development of engineering PD tests to measure the resistance to destruction of power cables and capacitor dielectrics leads to improved dielectric design and more reliable equipment     

Low-frequency noise in thick-film resistors due to two-steptunneling process in insulator layer of elemental MIM cell

In this paper, it is assumed that low-frequency noise source in thick-film resistors are fluctuations of the trap occupations by electrons, tunneling through insulator layer of the elemental cell. Two conducting particles separated by a thin insulating layer form the elemental cell (MIM structure). Trap charge fluctuations are modulating the MIM cell barrier, thus modulating the tunneling current and barrier resistance. A low frequency noise model is proposed under the assumption that the space distribution of traps in thick-film resistor is symmetrical with respect to the central plane of the MIM cell. Numerical results show that in the presence of small number of traps in insulator layer of the elemental cell, 1/f noise is exhibited in a narrow frequency range (4-5 decades). A model is applied on the experimental results for noise in thick-film resistors and a method of evaluation of the trapping state's parameters is discussed based on noise measurements