Physical Sciences and Engineering

Multilevel inverter is a very popular in various fields like FACTS devices,HVDC systems, industrial drives,photovoltaic systems etc. It has a large number of advantages like low stress on switches,lower harmonics,low switching losses etc. There are different topologies available like neutral point or diode clamped inverter, flying capacitor inverter etc. each having numerous disadvantages and advantages. The efficiency of this inverter is greatly improved by minimising the number of switches of the configuration used.

Ceramic powders of lead titanate, co- doped with copper (Pb0.9Cu0.1TiO3) and cobalt or zinc, of a perovskite structure were prepared by the sol-gel process by adopting the mode of the destabilization of colloidal solution. The effect of temperature and dopants on the structure of the obtained samples was studied by X-ray diffraction (RX), Raman spectroscopy and scanning electron microscopy (SEM). Analysis of the samples with fluorescence spectroscopy shows that Zn simultaneously occupies the sites A (Cu) and B (Ti) of the structure, creating oxygen vacancies.

Des échantillons de Pb(X0.20,Ti0.80)O3 (X= Lanthane, Magnésium, Manganèse, Calcium, Cuivre, Bismuth et Vanadium) ont été élaborés par la voie solide conventionnelle. Les températures de calcination, pour les différents échantillons élaborés, ont été choisies dans l’intervalle [800 °C, 900 °C]. La durée de calcination a été de 4 heures. La caractérisation par spectroscopie de diffraction des rayons X montre l’effet de l’élément dopant sur la phase cristalline, la température de calcination et la taille des cristallites des poudres fines élaborées.

The exact mechanism of mental fatigue is still not well understood even with the long history of neuroscience and psychology. It is said a human being undergoes mental fatigue when he or she just had a prolonged session of focusing on particular sustained attention task and this could particularly dangerous for certain tasks such as driving. Directed Attention Fatigue (DAF) is caused by an identified mechanic and was described a tug of war between bottom up attention mode and top down attention mode where DAF will cause decrease focus on the task on hand.

In this work, a novel hybrid method for the solutions of system of ordinary differential equations is presented here.The method creates trial solutions in genetic programming on grammatical evolution.The trial solutions are enhanced periodically using a local optimization procedure.

Measurement and control of surface roughness are important in many fields, such as magnetic media, semiconductor processing and optics. Typical roughness measurements are performed using stylus profilers, non-contact optical profilers, or scanning probe microscopes (SPM).An experimental approach for surface roughness evaluation based on the speckle pattern imaging has been attempted in this work by a simple configuration of setup consisting of laser, laboratory spectrometer, Beam Expander and CCD camera.

Antifouling refers to the process of control of fouling which occurs on liquid-solid surfaces. The term ‘fouling’ indicates an undesirable natural succession process during biofilm formation, in which a submerged surface or membranes becomes encrusted with material from the surrounding environment. It mainly involves microorganisms and their by-products developed on the surface by conditioning, attachment, biofilm formation followed by colonization. The accumulation of micro and macrofoulers on immersed structures results in economic as well as environmental losses.

In this paper we made a study on prime po-radicals in partially ordered ternary semiring and characterized these ideals. Mathematics Subject Classification: 16Y30, 16Y99.

In modern days the infrastructure of a country defines its true development, thus making construction sector more prominent. Countries like India are thus solemnly dependent on its construction sector for its rapid development. World-wide there are various building evaluation tools that focus on different areas of sustainable development and are designed for different types of projects. This research attempts to understand the various Green building rating system assessment criteria that need to be considered during comparison.

Due to the advent of new technologies, devices, and communication means like social networking sites, the amount of data produced by mankind is growing rapidly every year. The amount of data produced by us from the beginning of time till 2003 was 5 billion gigabytes. If you pile up the data in the form of disks it may fill an entire football field. The same amount was created in every two days in 2011, and in every ten minutes in 2013. This rate is still growing enormously.