Semiclassical quantization of multidimensional systems

Low order classical perturbation theory is used to obtain semiclassical eigenvalues for a system of three anharmonically coupled oscillators. The results in the low energy region studied here agree well with the "exact" quantum values. The latter had been calculated by matrix diagonalization using a large basis set

Diffusion at constant speed in a model phase space

We reconsider the problem of diffusion of particles at constant speed and present a generalization of the Telegrapher process to higher dimensional stochastic media ($d>1$), where the particle can move along $2^d$ directions. We derive the equations for the probability density function using the ``formulae of differentiation'' of Shapiro and Loginov. The model is an advancement over similiar models of photon migration in multiply scattering media in that it results in a true diffusion at constant speed in the limit of large dimensions.Comment: Final corrected version RevTeX, 6 pages, 1 figur

Sub-wavelength imaging: Resolution enhancement using metal wire gratings

An experimental evidence of subwavelength imaging with a "lens", which is a uniaxial negative permittivity wire medium slab, is reported. The slab is formed by gratings of long thin parallel conducting cylinders. Taking into account the anisotropy and spatial dispersion in the wire medium we theoretically show that there are no usual plasmons that could be exited on surfaces of such a slab, and there is no resonant enhancement of evanescent fields in the slab. The experimentally observed clear improvement of the resolution in the presence of the slab is explained as filtering out the harmonics with small wavenumbers. In other words, the wire gratings (the wire medium) suppress strong traveling-mode components increasing the role of evanescent waves in the image formation. This effect can be used in near-field imaging and detection applications.Comment: 12 pages, 6 figure

Solid Fuel rich Propellant Development for use in a Ramjet to Propel an Artillery Shell

This study describes the development of a fuel-rich propellant to be used in a solid fuel ramjet to provide active propulsion to a 155 mm artillery shell. Fuel-rich propellants consisting of aluminum, ammonium perchlorate and hydroxyl terminated polybutadiene were developed and their ballistic properties were measured to choose the appropriate fuel for the ramjet application. The attempts made were to enhance the burn rates of the propellant to provide required burn rates at lowest possible pressures in primary combustor of the ramjet. The propellant selection was done with reference of working time period of the base bleed unit, to calculate the required burn rate and corresponding pressure in primary combustor. It was observed that the fuel rich propellant of composition 35% ammonium perchlorate with 1 % Iron oxide embedded on it, 30 % mechanically activated aluminum with 10% polytetrafluoroethylene, and 25 % HTPB was found suitable for the above application. This provided the higher burn rates among all developed propellants with high pressure index of 0.58. This makes it suitable for the ramjet requiring higher burn rates at lower possible primary chamber pressures. The Young’s modulus and tensile strength of this propellant was measured to be 1.73 MPa and 0.24 MPa, respectively

Far Infrared Slab Lensing and Subwavelength Imaging in Crystal Quartz

We examine the possibility of using negative refraction stemming from the phonon response in an anisotropic crystal to create a simple slab lens with plane parallel sides, and show that imaging from such a lens should be possible at room temperature despite the effects of absorption that are inevitably present due to phonon damping. In particular, we consider the case of crystal quartz, a system for which experimental measurements consistent with all-angle negative refraction have already been demonstrated. Furthermore, we investigate the possibility of subwavelength imaging from such materials, and show that it should be possible for certain configurations.Comment: 12 pages, 10 figure

Magnifying perfect lens and superlens design by coordinate transformation

The coordinate transformation technique is applied to the design of perfect lenses and superlenses. In particular, anisotropic metamaterials that magnify two-dimensional planar images beyond the diffraction limit are designed by the use of oblate spheroidal coordinates. The oblate spheroidal perfect lens or superlens can naturally be used in reverse for lithography of planar subwavelength patterns.Comment: 8 pages, 8 figures, v2: submitted, v3: accepted by Physical Review

Synchronization of Grid Connected PV System Using PI Controller

Grid connected solar system consists ofconverters Circuits are organized in two differentways one is DC/DC boosters and another is PWMInverter. This combination results decrement ofQuality and efficiency of electric power, this paperreflects the use of a single phase 13- level photovoltaic (PV) inverter in solar system connected togrid with a pulse width-modulated (PWM) controlsystem. The rapid variations in radiation can beremunerated by Digital proportional-integralcontroller. This inverter gives a less harmonicdistortion and significant power factor over fivelevel inverters and is examined and experimentedthrough simulation

Alfisols of the Semi-Arid Tropics: Problems and Potentials

Alfisols are the third most important soil order in the world, covering 13.1% of the world area. In the semi-arid tropics, Alfisols cover a much larger area of potentially arable and grazable lands than Vertisols, which have until now received far more attention from ICRISAT researchers. About 62% of the world’s Alfisols are located in West Africa and Indi

Polymer thin film with in situ synthesized silver nanoparticles as a potent reusable bactericide

Silver nanoparticles are well-established antibacterial agents. However, an effective design and formulation that ensures: (i) ease of synthesis and fabrication, (ii) amenability to deployment over large surfaces of variable shape, (iii) high efficacy and (iv) multiple reuses with the possibility of periodic monitoring, is yet to emerge. A nanocomposite thin film of poly(vinyl alcohol) with silver nanoparticles generated within, through a soft-chemical in situ synthesis, is shown to be a good candidate to fulfil most of the above requirements. Efficient antibacterial activity, multiple reuses and facile monitoring of the film through spectroscopy and microscopy are demonstrated. Preliminary studies demonstrate the effective bactericidal action of the thin film coating on stirring rods