Periodic response of nonlinear systems

A procedure is developed to determine approximate periodic solutions of autonomous and non-autonomous systems. The trignometric collocation method (TCM) is formalized to allow for the analysis of relatively small order systems directly in physical coordinates. The TCM is extended to large order systems by utilizing modal analysis in a component mode synthesis strategy. The procedure was coded and verified by several check cases. Numerical results for two small order mechanical systems and one large order rotor dynamic system are presented. The method allows for the possibility of approximating periodic responses for large order forced and self-excited nonlinear systems

Theoretical studies of the atomic transitions in boron-like ions: Mg VIII, Si X and S XII

In this paper, we have carried out the calculations of the weighted oscillator strengths and the transition probabilities for a few low-lying transitions of boron-like ions: Mg VIII, Si X and S XII which are astrophysically important, particularly, in the atmospheres of the solar corona. We have employed an all-order relativistic many-body theory called the relativistic coupled-cluster theory to calculate very precisely these atomic quantities of astrophysical interest. We have reported for the first time the transition probabilities for some forbidden transitions which are unavailable in the literature; either theoretically or experimentally. We also discuss the physical effects associated with these transitions. Our data can be used for the identification of spectral lines arising from the coronal atmospheres of Sun and Sun-like stars having an extended corona.Comment: 8 pages, 4 table

Study of resistance pattern of isolated micro-organisms towards commonly used anti-microbial agents in medical intensive care unit of a tertiary care teaching hospital

Background: The objective of the study was to find out different types of biological samples from admitted patients tested for culture and sensitivity (C&S), prevalence of different types of organisms isolated from those samples, and to analyze the resistance pattern of those isolated organisms against commonly used or tested anti-microbial agents (AMAs).Methods: Following institutional ethics committee approval and written informed consent, adult patients of both genders, receiving AMAs were enrolled from June 2014 to July 2015 and followed up daily till they were in medical intensive care unit (MICU). Demographic data, diagnosis, culture-sensitivity (antibiogram) and other investigation reports and treatment details were recorded. Descriptive statistical analysis of collected data was done.Results: Of the 514 samples (from 600 patients enrolled) sent for C&S testing, 143 were reported as sterile while from the rest 371 samples, 504 organisms were isolated; commonly isolated organisms were Pseudomonas aeruginosa (30%), Acinetobacter baumannii (23%), Klebsiella pneumoniae (16%), Providencia sp. (7.1%), Escherichia coli (5.7%), and Enterobacter sp. (4.2%). Samples were sent in 63% of enrolled patients, the commonest being broncho-alveolar lavage (48% of total). Microbial resistance was high for cephalosporins (ceftriaxone, cefepime, ceftazidime), carbapenems (meropenem, imipenem), penicillins (piperacillin), quinolones (ciprofloxacin, levofloxacin), aminoglycosides (gentamicin, netilmicin, amikacin) and cotrimoxazole. Most organisms were sensitive to colistin (100%), polymyxin B (92%) and tigecycline (69%).Conclusions: The information regarding commonly isolated organisms and their resistant pattern would aid in rational selection of AMAs and thus the present study is useful to clinicians managing MICU and the hospital infection committee to plan future policies regarding AMA use in MICU

Intrinsic Electric Dipole Moments of Paramagnetic Atoms: Rubidium and Cesium

The electric dipole moment (EDM) of paramagnetic atoms is sensitive to the intrinsic EDM contribution from that of its constituent electrons and a scalar--pseudo-scalar (S-PS) electron-nucleus interactions. The electron EDM and the S-PS EDM contribution to atomic EDM scales as Z^3. Thus, the heavy paramagnetic atomic systems will exhibit large enhancement factors. However, the nature of the coupling is so small that it becomes an interest of high precision atomic experiments. In this work, we have computed the EDM enhancement factors of the ground states of Rb and Cs due to both the electron EDM and the S-PS EDM using the relativistic coupled-cluster (RCC) theory. The importance of obtaining the precise enhancement factors and the experimental results in deducing a reliable limit on the electron EDM is emphasized.Comment: 4 pages, 1 figur

The electron electric dipole moment enhancement factors of Rubidium and Caesium atoms

The enhancement factors of the electric dipole moment (EDM) of the ground states of two paramagnetic atoms; rubidium (Rb) and caesium (Cs) which are sensitive to the electron EDM are computed using the relativistic coupled-cluster theory and our results are compared with the available calculations and measurements. The possibility of improving the limit for the electron EDM using the results of our present work is pointed out.Comment: AISAMP7 Conference paper, Accepted in Journal of Physics: Conference Series: 200

Rotating compact star with superconducting quark matter

A compact star with superconducting quark core, the hadron crust and the mixed phase between the two is considered. The quark meson coupling model for hadron matter and the color flavor locked quark model for quark matter is used in order to construct the equation of state for the compact star. The effect of pairing of quarks in the color flavor locked phase and the mixed phase on the mass, radius, and period of the rotating star is studied.Comment: 11 pages, 5 figure

FABRICATION, CHARACTERIZATION AND FINITE ELEMENT ANALYSIS OF ALUMINIUM BASED METAL MATRIX COMPOSITES FOR AUTOMOBILE CLUTCH HUB

Experiments have been conducted under laboratory condition to assess the mechanical characteristics of the hybrid composites with aluminium matrix A356 alloy, reinforced with Graphite and Flyash. This has been possible by fabricating the samples through usual stir casting technique. Scanning electron microscopy was used for microstructure analysis. Chemical characterization of both matrix and composites was carried out by using Energy Dispersive x-ray Spectroscopy., hardness, Density tensile and compression studies were carried out on both the alloy and composites.  Improved hardness and compression properties were observed for all the composites. Interestingly improved tensile properties were observed for all the composites than alloy. Dispersion of Graphite and Flyash particles in aluminium matrix improves the hardness of the matrix material and also the mechanical behavior of the composite