Studies on some generalizations of line graph and the power domination problem in graphs

Department of Mathematics, Cochin University of Science and Technology

Survey of coral lagoons of Laksbadweep Atolls using line intercept transect (LIT) technique

The present study aims at surveying the coral lagoons of four islands viz. Kavarathi, Kalpeni, Kadmat and Agathi, which include quantitative survey of the major benthic forms using Line Intercept Transect (LIT) technique and hydrographical study of these lagoon waters The distribution of PHC in the lagoons has also been followed to understand, the effects of introduction of flat bottomed ferry boats to the islands.From a biological monitoring stand point for the assessment of manmade disturbance of the coral reefs, it IS highly essential to identify faunal assemblages which will contain 'flag-stones' specIes as indicators of such disturbances. Among the known faunal assemblages In coral reefs the most diverse groups of sensitive species belongs to bryozoan assemblage. Therefore, the most common species of bryozoans distributed along the atolls and reef flats were collected and described in this work Along with this, bryozoans associated with coral from other parts of Indian ocean have also been added so as to provide a comprehensive picture of the distribution of bryozoans in the coral reefs.

Self-consistent theory of current and voltage noise in multimode ballistic conductors

Electron transport in a self-consistent potential along a ballistic two-terminal conductor has been investigated. We have derived general formulas which describe the nonlinear current-voltage characteristics, differential conductance, and low-frequency current and voltage noise assuming an arbitrary distribution function and correlation properties of injected electrons. The analytical results have been obtained for a wide range of biases: from equilibrium to high values beyond the linear-response regime. The particular case of a three-dimensional Fermi-Dirac injection has been analyzed. We show that the Coulomb correlations are manifested in the negative excess voltage noise, i.e., the voltage fluctuations under high-field transport conditions can be less than in equilibrium.

Nuclei beyond the drip line

In the Thomas-Fermi model, calculations are presented for nuclei beyond the nuclear drip line at zero temperature. These nuclei are in equilibrium by the presence of an external gas, as may be envisaged in the astrophysical scenario. We find that there is a limiting asymmetry beyond which these nuclei can no longer be made stable.

Establishment and characterization of India's first marine fish cell line (SISK) from the kidney of sea bass (Lates calcarifer)

A continuous cell line (SISK) from kidney of sea bass, Lates calcarifer, has been established and characterized. The cell line was maintained in Leibovitz' L-15 supplemented with 15% fetal bovine serum. This cell line has been subcultured more than 100 times over a period of 2 years. The SISK cell line consists of predominantly of epithelial-like cells. These cells showed strong positive for epithelial markers such as cytokeratin 19 and pancytokeratin. The cells were able to grow at temperature between 25 and 32 °C with optimum temperature of 28 °C. The growth rate of sea bass kidney cells increased as the FBS proportion increased from 2% to 20% at 28 °C with optimum growth at the concentrations of 15% or 20% FBS. The distribution of chromosome number was 30 to 56 with a modal peak at 48 chromosomes. Polymerase chain reaction products were obtained from SISK cells and tissues of sea bass with primer sets of microsatellite markers of sea bass. Five fish viruses were tested on this cell line to determine its susceptibility to these viruses and this was found to be susceptible to MABV NC1 and nodavirus, and the infection was confirmed by RT-PCR and CPE. This suggests that the SISK cell line has good potential for the isolation of various fish viruses. This cell line has been shown to be susceptible to bacterial extracellular products. The SISK cell line is the India's first marine fish cell line.

k-NN based On-Line Handwritten Character recognition system

On-line handwriting recognition has been a frontier area of research for the last few decades under the purview of pattern recognition. Word processing turns to be a vexing experience even if it is with the assistance of an alphanumeric keyboard in Indian languages. A natural solution for this problem is offered through online character recognition. There is abundant literature on the handwriting recognition of western, Chinese and Japanese scripts, but there are very few related to the recognition of Indic script such as Malayalam. This paper presents an efficient Online Handwritten character Recognition System for Malayalam Characters (OHR-M) using K-NN algorithm. It would help in recognizing Malayalam text entered using pen-like devices. A novel feature extraction method, a combination of time domain features and dynamic representation of writing direction along with its curvature is used for recognizing Malayalam characters. This writer independent system gives an excellent accuracy of 98.125% with recognition time of 15-30 milliseconds

On-Line Handwritten Character Recognition using Kohonen Networks

This paper presents an efficient Online Handwritten character Recognition System for Malayalam Characters (OHR-M) using Kohonen network. It would help in recognizing Malayalam text entered using pen-like devices. It will be more natural and efficient way for users to enter text using a pen than keyboard and mouse. To identify the difference between similar characters in Malayalam a novel feature extraction method has been adopted-a combination of context bitmap and normalized (x, y) coordinates. The system reported an accuracy of 88.75% which is writer independent with a recognition time of 15-32 milliseconds

Slot Line Fed Dipole Antenna For Wide Band Applications

A slot line fed planar dipole antenna with a parasitic strip for wide band applications is presented. The presented antenna offers a 2:1 VSWR bandwidth from 1.66 to 2.71 GHz covering the DCS/ PCS/UMTS and IEEE 802.11b/g bands with a gain better than 6.5 dBi. The uniplanar design, simple feeding, and high gain make it a versatile antenna for wireless applications

FEM based Virtual Prototyping and Design of Third Harmonic Excitation System for Low Voltage Brushless Alternators

Salient pole brushless alternators coupled to IC engines are extensively used as stand-by power supply units for meeting in- dustrial power demands. Design of such generators demands high power to weight ratio, high e ciency and low cost per KVA out- put. Moreover, the performance characteristics of such machines like voltage regulation and short circuit ratio (SCR) are critical when these machines are put into parallel operation and alterna- tors for critical applications like defence and aerospace demand very low harmonic content in the output voltage. While designing such alternators, accurate prediction of machine characteristics, including total harmonic distortion (THD) is essential to mini- mize development cost and time. Total harmonic distortion in the output voltage of alternators should be as low as possible especially when powering very sophis- ticated and critical applications. The output voltage waveform of a practical AC generator is replica of the space distribution of the ux density in the air gap and several factors such as shape of the rotor pole face, core saturation, slotting and style of coil disposition make the realization of a sinusoidal air gap ux wave impossible. These ux harmonics introduce undesirable e ects on the alternator performance like high neutral current due to triplen harmonics, voltage distortion, noise, vibration, excessive heating and also extra losses resulting in poor e ciency, which in turn necessitate de-rating of the machine especially when connected to non-linear loads. As an important control unit of brushless alternator, the excitation system and its dynamic performance has a direct impact on alternator's stability and reliability. The thesis explores design and implementation of an excitation i system utilizing third harmonic ux in the air gap of brushless al- ternators, using an additional auxiliary winding, wound for 1=3rd pole pitch, embedded into the stator slots and electrically iso- lated from the main winding. In the third harmonic excitation system, the combined e ect of two auxiliary windings, one with 2=3rd pitch and another third harmonic winding with 1=3rd pitch, are used to ensure good voltage regulation without an electronic automatic voltage regulator (AVR) and also reduces the total harmonic content in the output voltage, cost e ectively. The design of the third harmonic winding by analytic methods demands accurate calculation of third harmonic ux density in the air gap of the machine. However, precise estimation of the amplitude of third harmonic ux in the air gap of a machine by conventional design procedures is di cult due to complex geome- try of the machine and non-linear characteristics of the magnetic materials. As such, prediction of the eld parameters by conven- tional design methods is unreliable and hence virtual prototyping of the machine is done to enable accurate design of the third har- monic excitation system. In the design and development cycle of electrical machines, it is recognized that the use of analytical and experimental methods followed by expensive and in exible prototyping is time consum- ing and no longer cost e ective. Due to advancements in com- putational capabilities over recent years, nite element method (FEM) based virtual prototyping has become an attractive al- ternative to well established semi-analytical and empirical design methods as well as to the still popular trial and error approach followed by the costly and time consuming prototyping. Hence, by virtually prototyping the alternator using FEM, the important performance characteristics of the machine are predicted. Design of third harmonic excitation system is done with the help of results obtained from virtual prototype of the machine. Third harmonic excitation (THE) system is implemented in a 45 KVA ii experimental machine and experiments are conducted to validate the simulation results. Simulation and experimental results show that by utilizing third harmonic ux in the air gap of the ma- chine for excitation purposes during loaded conditions, triplen harmonic content in the output phase voltage is signi cantly re- duced. The prototype machine with third harmonic excitation system designed and developed based on FEM analysis proved to be economical due to its simplicity and has the added advan- tage of reduced harmonics in the output phase voltage.

On-line analytical processing with conceptual information systems

A conceptual information system consists of a database together with conceptual hierarchies. The management system TOSCANA visualizes arbitrary combinations of conceptual hierarchies by nested line diagrams and allows an on-line interaction with a database to analyze data conceptually. The paper describes the conception of conceptual information systems and discusses the use of their visualization techniques for on-line analytical processing (OLAP).

A finite state model for on-line analytical processing in triadic contexts

About ten years ago, triadic contexts were presented by Lehmann and Wille as an extension of Formal Concept Analysis. However, they have rarely been used up to now, which may be due to the rather complex structure of the resulting diagrams. In this paper, we go one step back and discuss how traditional line diagrams of standard (dyadic) concept lattices can be used for exploring and navigating triadic data. Our approach is inspired by the slice & dice paradigm of On-Line-Analytical Processing (OLAP). We recall the basic ideas of OLAP, and show how they may be transferred to triadic contexts. For modeling the navigation patterns a user might follow, we use the formalisms of finite state machines. In order to present the benefits of our model, we show how it can be used for navigating the IT Baseline Protection Manual of the German Federal Office for Information Security.

Klassifikationsgestützte on-line Adaption eines robusten beobachterbasierten Fehlerdiagnoseansatzes für nichtlineare Systeme

Diese Arbeit behandelt die Problemstellung der modellbasierten Fehlerdiagnose für Lipschitz-stetige nichtlineare Systeme mit Unsicherheiten. Es wird eine neue adaptive Fehlerdiagnosemethode vorgestellt. Erkenntnisse und Verfahren aus dem Bereich der Takagi-Sugeno (TS) Fuzzy-Modellbildung und des Beobachterentwurfs sowie der Sliding-Mode (SM) Theorie werden genutzt, um einen neuartigen robusten und nichtlinearen TS-SM-Beobachter zu entwickeln. Durch diese Zusammenführung lassen sich die jeweiligen Vorteile beider Ansätze miteinander kombinieren. Bedingungen zur Konvergenz des Beobachters werden als lineare Matrizenungleichungen (LMIs) abgeleitet. Diese Bedingungen garantieren zum einen die Stabilität und liefern zum anderen ein direktes Entwurfsverfahren für den Beobachter. Der Beobachterentwurf wird für die Fälle messbarer und nicht messbarer Prämissenvariablen angegeben. Durch die TS-Erweiterung des in dieser Arbeit verwendeten SM-Beobachters ist es möglich, den diskontinuierlichen Rückführterm mithilfe einer geeigneten kontinuierlichen Funktion zu approximieren und dieses Signal daraufhin zur Fehlerdiagnose auszuwerten. Dies liefert eine Methodik zur Aktor- und Sensorfehlerdiagnose nichtlinearer unsicherer Systeme. Gegenüber anderen Ansätzen erlaubt das Vorgehen eine quantitative Bestimmung und teilweise sogar exakte Rekonstruktion des Fehlersignalverlaufs. Darüber hinaus ermöglicht der Ansatz die Berechnung konstanter Fehlerschwellen direkt aus dem physikalischen Vorwissen über das betrachtete System. Durch eine Erweiterung um eine Betriebsphasenerkennung wird es möglich, die Schwellenwerte des Fehlerdiagnoseansatzes online an die aktuelle Betriebsphase anzupassen. Hierdurch ergibt sich in Betriebsphasen mit geringen Modellunsicherheiten eine deutlich erhöhte Fehlersensitivität. Zudem werden in Betriebsphasen mit großen Modellunsicherheiten Falschalarme vermieden. Die Kernidee besteht darin, die aktuelle Betriebsphase mittels eines Bayes-Klassikators in Echtzeit zu ermitteln und darüber die Fehlerschwellen an die a-priori de nierten Unsicherheiten der unterschiedlichen Betriebsphasen anzupassen. Die E ffektivität und Übertragbarkeit der vorgeschlagenen Ansätze werden einerseits am akademischen Beispiel des Pendelwagens und anderseits am Beispiel der Sensorfehlerdiagnose hydrostatisch angetriebener Radlader als praxisnahe Anwendung demonstriert.

Optimization of the Mechanical and Optical Properties of Tunable Optical Sensor Arrays (TOSA) for a Nanospectrometer in the Visible and Near Infrared Spectral Range

Tunable Optical Sensor Arrays (TOSA) based on Fabry-Pérot (FP) filters, for high quality spectroscopic applications in the visible and near infrared spectral range are investigated within this work. The optical performance of the FP filters is improved by using ion beam sputtered niobium pentoxide (Nb2O5) and silicon dioxide (SiO2) Distributed Bragg Reflectors (DBRs) as mirrors. Due to their high refractive index contrast, only a few alternating pairs of Nb2O5 and SiO2 films can achieve DBRs with high reflectivity in a wide spectral range, while ion beam sputter deposition (IBSD) is utilized due to its ability to produce films with high optical purity. However, IBSD films are highly stressed; resulting in stress induced mirror curvature and suspension bending in the free standing filter suspensions of the MEMS (Micro-Electro-Mechanical Systems) FP filters. Stress induced mirror curvature results in filter transmission line degradation, while suspension bending results in high required filter tuning voltages. Moreover, stress induced suspension bending results in higher order mode filter operation which in turn degrades the optical resolution of the filter. Therefore, the deposition process is optimized to achieve both near zero absorption and low residual stress. High energy ion bombardment during film deposition is utilized to reduce the film density, and hence the film compressive stress. Utilizing this technique, the compressive stress of Nb2O5 is reduced by ~43%, while that for SiO2 is reduced by ~40%. Filters fabricated with stress reduced films show curvatures as low as 100 nm for 70 μm mirrors. To reduce the stress induced bending in the free standing filter suspensions, a stress optimized multi-layer suspension design is presented; with a tensile stressed metal sandwiched between two compressively stressed films. The stress in Physical Vapor Deposited (PVD) metals is therefore characterized for use as filter top-electrode and stress compensating layer. Surface micromachining is used to fabricate tunable FP filters in the visible spectral range using the above mentioned design. The upward bending of the suspensions is reduced from several micrometers to less than 100 nm and 250 nm for two different suspension layer combinations. Mechanical tuning of up to 188 nm is obtained by applying 40 V of actuation voltage. Alternatively, a filter line with transmission of 65.5%, Full Width at Half Maximum (FWHM) of 10.5 nm and a stopband of 170 nm (at an output wavelength of 594 nm) is achieved. Numerical model simulations are also performed to study the validity of the stress optimized suspension design for the near infrared spectral range, wherein membrane displacement and suspension deformation due to material residual stress is studied. Two bandpass filter designs based on quarter-wave and non-quarter-wave layers are presented as integral components of the TOSA. With a filter passband of 135 nm and a broad stopband of over 650 nm, high average filter transmission of 88% is achieved inside the passband, while maximum filter transmission of less than 1.6% outside the passband is achieved.

Grupo de trabajo on line de prevenci??n de riesgos

Se presenta experiencia educativa que propone el proceso de formaci??n y desarrollo de un grupo de trabajo formado por profesorado de las distintas etapas educativas. Lo realiza la Delegaci??n de Educaci??n de Granada. El objetivo principal es: fomentar una aut??ntica cultura preventiva mediante la promoci??n de la mejora de la educaci??n en dicha materia en todos los ??mbitos educativos.