Inductive Algebras for Finite Heisenberg Groups

A characterization of the maximal abelian sub-algebras of matrix algebras that are normalized by the canonical representation of a finite Heisenberg group is given. Examples are constructed using a classification result for finite Heisenberg groups.Comment: 5 page

Flux pump for HTS rotating machinery applications

High Temperature Superconducting (HTS) machines offer several benefits over the conventional machines. With the advent of YBCO materials, research and development in HTS applications has gained significant impetus. The application of flux pump has its own advantages over the conventional mechanism for magnetic field generation in superconductors. This paper reviews few relevant works and presents preliminary results from experiments carried out to provide justification on the application of flux pump for generating magnetic flux in a rotating machine

Demosaicing of Color Images by Accurate Estimation of Luminance

Digital cameras acquire color images using a single sensor with Color filter Arrays. A single color component per pixel is acquired using color filter arrays and the remaining two components are obtained using demosaicing techniques. The conventional demosaicing techniques existent induce artifacts in resultant images effecting reconstruction quality. To overcome this drawback a frequency based demosaicing technique is proposed. The luminance and chrominance components extracted from the frequency domain of the image are interpolated to produce intermediate demosaiced images. A novel Neural Network Based Image Reconstruction Algorithm is applied to the intermediate demosaiced image to obtain resultant demosaiced images. The results presented in the paper prove the proposed demosaicing technique exhibits the best performance and is applicable to a wide variety of images

The Design of Control Strategy for Blended Series-Parallel Power-Split PHEV – a Simulation Study

Electric Vehicles (EVs) have been extensively researched to reduce the fuel consumption and tailpipe emission. The series-parallel power-split Plug-in Electric Vehicle (PHEV) has been considered as one of the most suitable candidates. It contains both an internal combustion engine (ICE) and an electrical storage system (ESS) to achieve a better driving performance. The energy management system (EMS) is significant for a PHEV to improve the efficiency of the whole system. Electric vehicle mode (EV), charging depletion (CD) and charging sustaining (CS) modes will be discussed to build a control strategy in this study. This control strategy will be implemented with the state of charge (SoC) to show its impact through a simulation study

Properties of a New Dental Porcelain

A high strength dental porcelain OPTEC, HSP™ has recently been introduced for use in the fabrication of crowns, three-unit anterior bridges with a single pontic, inlays, on lays, veneers, etc., without a metal substrate. This investigation reports the results of our research involving the characterization of the structure properties and thermally induced transformations of this porcelain. It has been found that the material possesses superior strength and other properties relative to conventional porcelains. The improved properties appear to result from the presence of a very fine and relatively dense distribution of leucite crystals. Scanning electron microscopy indicates, however, that the new product needs additional optimization to improve uniformity of crystallite distribution. Scanning electron microscopy and X-ray diffraction studies also reveal well defined structural and crystallographic transformations during thermal treatment at selected temperature ranges. The primary transformation appears to be crystallization of metastable sanidine from the glass matrix. The crystallization of sanidine leads to a translucent to opaque transition. The transformations appear to follow the phase transitions expected from the phase diagrams

Inductive algebras and homogeneous shifts

Inductive algebras for the irreducible unitary representations of the universal cover of the group of unimodular two by two matrices are classified. The classification of homogeneous shift operators is obtained as a direct consequence. This gives a new approach to the results of Bagchi and Misra

Voltage Response Measurements for the Diagnosis of Insulation Condition in Power Transformer

A large proportion of existing transformers within electric utilities are approaching the end of their design life. Insulation degradation continues to be a major concern for these transformers. Insulation materials degrade at higher temperatures in the presence of oxygen and moisture. The degradation from thermal stress affects electrical, chemical and mechanical properties. Utility engineers use a number of modern diagnostic techniques to assess the insulation condition of aged transformers. Among them Dissolved Gas Analysis (DGA), Degree of Polymerisation (DP) measurement and Furan analysis by the High Performance Liquid Chromatography (HPLC) are frequently used. In recent years, new diagnostic methods have been promoted to complement the classical insulation resistance, power frequency dissipation factor and polarisation index measurements. These new methods are based on time or frequency domain polarisation measurements. In frequency domain measurement, a sinusoidal voltage is applied and the complex dielectric constant is determined from the amplitude and phase of the current flowing through the sample. On the other hand, time domain measurements are conducted by the application of a step voltage across the insulation sample. Time domain measurements based on polarisation and depolarisation current measurements and return voltage measurements have gained significant attention over the last several years. Particularly, there has been growing interest in the condition assessment of transformer insulation by the Return Voltage Method (RVM). In recent times decay voltage measurement has also been proposed to monitor the moistening process of insulation after polarising the insulation for a long time. Polarisation and depolarisation currents have two components - conductive current and polarisation current. The conductive component provides information about the intensity of the conduction process and the polarisation component provides the intensity of the polarisation processes within a defined time range. It is difficult to separate the two components of currents and the measurement of such small current is also sensitive to electromagnetic disturbances. The principle of the voltage response method is based on the measurement of the discharge and return voltages of the insulation. From the magnitude and shape of the voltage curves the quality of insulation affected by moisture and ageing can be predicted. Moisture content of the insulation can be estimated from the decay voltage measurement, while progress of thermal ageing can be estimated from the return voltage measurement. The two measurements can be conducted independently and hence conduction and polarisation processes can be investigated independently. In this research project we have investigated a number of transformers of different ages with the return voltage and decay voltage techniques. A brief analysis of the decay and return voltage methods will first be outlined in this paper. Then results from the two groups of measurements (one from the decay voltage and the other from the return voltage) will be presented