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Search Results: 1 - 10 of 499931 matches for " M. K. Sharma "
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Comparative Finite Element Analysis of Jaipur Foot and Polyurethane Foot  [PDF]
Priya Sharma, Shubhda Sharma, S. Vidhya, M. K. Mathur
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510B106
Abstract:

FEA is amongst best methods that help users to solve complex problems. There are fixed number of nodes in each ele-ment of the model that define the element boundaries to which boundary condition and loads can be applied. The geo-metry of the structure, the load applications, stress and displacement gradients can be approximated in a accurate man-ner, if the mesh is finer. The problem with the foot was unusual cracks in JP Foot and early breakage of PU Foot due to crack propagation[1]. To solve this problem we modelled the foot using SolidWorks and performed FEA Analysis for single leg below knee amputee patients. After analysis, it has been concluded that JP Foot as compared to PU Foot has more stress bearing capacity but has less displacement threshold due to its material properties[2]. This work will lead to optimization of both the feet thus enhancing the durability of foot.

 

Evidence of double magicity of N=Z nuclei near the rp-process path
M. M. Sharma,J. K. Sharma
Physics , 2009,
Abstract: N=Z nuclei above Ni are understood to be waiting-point nuclei in the rp-process nucleosynthesis. Investigating the experimental isotope shifts in Kr isotopes near the proton drip-line, we have discovered that N=Z rp-process nuclei $^{68}$Se, $^{72}$Kr, $^{76}$Sr and $^{80}$Zr exhibit a significant shell gap both at the proton and neutron numbers in the deformed space with the consequence that pairing correlations for protons and neutrons vanish, thus lending a double-magic character to these nuclei. A significant number of nuclei in this region are also shown to exhibit neutron magicity at N = 34, 36, 38, and 40 in the deformed space.
Revelation of double magicity in N=Z nuclei in the rp-process region
M. M. Sharma,J. K. Sharma
Physics , 2010, DOI: 10.1063/1.3431413
Abstract: In rapid-proton capture (rp-process), N=Z nuclei above Ni are understood to act as waiting-point nuclei. The N=Z nuclei 68Se, 72Kr, 76Sr and 80Zr among others are known to give rise to a large-energy x-ray flux and peaks in abundances of these nuclei synthesized in the astrophysical rp-process. Investigating the experimental isotope shifts in Kr isotopes near the proton drip-line within the framework of the deformed Relativistic Hartree-Bogoliubov theory, we have discovered that N=Z rp-process nuclei 68Se, 72Kr, 76Sr and 80Zr exhibit large shell gap both at the proton and neutron numbers in the deformed space with the consequence that pairing correlations for protons and neutrons vanish. This lends a doubly magic character to these nuclei. A significant number of nuclei in this region are also shown to exhibit neutron magicity at N=34, 36, 38, and 40 in the deformed space. A unique case of concomitance of the double magicity and the shape-coexistence is found for 68Se.
Synthesis and Characterization of LPCVD Polysilicon and Silicon Nitride Thin Films for MEMS Applications
N. Sharma,M. Hooda,S. K. Sharma
Journal of Materials , 2014, DOI: 10.1155/2014/954618
Abstract: Inherent residual stresses during material deposition can have profound effects on the functionality and reliability of fabricated MEMS devices. Residual stress often causes device failure due to curling, buckling, or fracture. Typically, the material properties of thin films used in surface micromachining are not very well controlled during deposition. The residual stress, for example, tends to vary significantly for different deposition conditions; experiments were carried out to study the polysilicon and silicon nitride deposited by Low Pressure Chemical Vapor Deposition (LPCVD) method at wide range of process conditions. High temperature annealing effects on stress in case polysilicon are also reported. The reduced residual stress levels can significantly improve device performance, reliability, and yield as MEMS devices become smaller. 1. Introduction The deposition of thin films is an important field of Micro Electro Mechanical Systems (MEMS) or micro system technology. Most of the thin films exhibit stress after deposition. This stress has many different causes. Most films are deposited at elevated temperature. If the thermal expansions of the film and substrate are not identical there will be stress between them after cooling. Other sources are lattice mismatch, crystallization, atomic peening, incorporation of foreign atoms, microscopic voids, variation of interatomic spacing with crystal size, crystallite coalescence at grain boundaries, phase transformations, and texture effect. Sometimes this stress is called internal stress or residual stress. This stress may cause problem for thin film technology. It changes the behavior of the thin films often in an uncontrolled manner (Figure 1 shows the one of the structure under stress), reducing the yields and long term durability and sometimes causing fracture. Many researchers had investigated the mechanical response of thin films, for example. Frequently, each particular investigation involving MEMS tends to be device dependent; type of film used and deposition methods adopted, and introduces new fundamental questions. Progress in this field has leaned towards providing more specific technological solutions rather than generating a basic understanding of mechanical behavior. Figure 1: Effect of residual stress on free standing structure. In the recently developed technology of microsystem, more and more standing thin film structures are used, for example, resonator, movable parts in surface micromachining, thin film membranes, and cantilever beams in transduction [1, 2]. For these applications, the
On partition function in Astronomy \& Astrophysics
M. K. Sharma,Monika Sharma,Suresh Chandra
Physics , 2015,
Abstract: In order to analyze spectrum from the interstellar medium (ISM), spectrum of the molecule of interest is recorded in a laboratory, and accurate rotational and centrifugal distortion constants are derived. By using these constants, one can calculate accurate partition function. However, in the same paper, where these constants are derived, the partition function is calculated by using a semi-empirical expression. We have looked into the details of this semi-empirical expression and compared the values, obtained from it, with the accurate ones. As an example, we have considered the case of Methanimine (CH$_2$NH) which is detected in a number of cosmic objects. It is found that for the kinetic temperature $T > 120$ K, the semi-empirical expression gives large value as compared to the accurate one. The deviation becomes about 25\% larger than the accurate one at the kinetic temperature of 400 K.
Some observations about the MOLSCAT
M. K. Sharma,Monika Sharma,Suresh Chandra
Physics , 2015,
Abstract: For calculation of cross sections for collisional transitions between rotational levels in a molecule, a computer code, MOLSCAT has been developed by Hutson \& Green (1994). For the transitions between rotational levels in H$_2$CS due to collisions with He atom, we have calculated cross sections under the CS approximation. In the MOLSCAT, there is provision to input more than one values of total energies. Here, for example, we are interested in the cross sections for total energy 11 cm$^{-1}$. The calculations have been done for the single energy 11 cm$^{-1}$ and for eight combinations, having energies (11, 12), (12, 11), (10, 11), (11, 10), (11, 12, 13), (9, 10, 11), (10, 11, 12), (9, 10, 11, 12, 13) cm$^{-1}$. We have found that the cross sections for 11 cm$^{-1}$, in general, differ from one another in all the 9 calculations. The reason for the difference in the results appears that the MOLSCAT uses the intermediate data of calculations for one energy, in the calculations for other energies. Under such circumstances, the possible suggestion can be to run the MOLSCAT for a single energy at a time.
Short-Term Orbit Prediction with J2 and Mean Orbital Elements  [PDF]
Shraddha Gupta, M. Xavier James Raj, R. K. Sharma
International Journal of Astronomy and Astrophysics (IJAA) , 2011, DOI: 10.4236/ijaa.2011.13018
Abstract: An analytical theory for calculating perturbations of the orbital elements of a satellite due to J2 to accuracy up to fourth power in eccentricity is developed. It is observed that there is significant improvement in all the orbital elements with the present theory over second-order theory. The theory is used for computing the mean orbital elements, which are found to be more accurate than provided by Bhatnagar and taqvi’s theory (up to second power in eccentricity). Mean elements have a large number of practical applications.
Transport Properties of the Layer Manganite La1.5Ca1.5Mn2-xFexO7  [PDF]
M. P. Sharma, Anjali Krishnamurthy, Bipin K. Srivastava
World Journal of Condensed Matter Physics (WJCMP) , 2011, DOI: 10.4236/wjcmp.2011.14022
Abstract: Layered perovskite manganite ceramics with a nominal chemistry La1.5Ca1.5Mn2-xFexO7(x = 0.0, 0.05, 0.1, 0.3, 0.5) were prepared using sol-gel method. The manganese ions are highly mixed states of Mn3+ and Mn4+. It is found that the Mn3+/Mn4+ ratio decreases with the Fe doping content increasing. The conductivity and magnetoresistance (MR) were studied. The sample of x = 0.05 shows metal insulator transition (MIT) at 135 K. The MIT peak temperature (Tp) shifts towards higher temperature with increasing applied magnetic field. All the samples can be well fitted to the variable-range hopping (VRH) model. The maximum value of MR (%) [ρ(0) - ρ(H)]/ρ(0) × 100 for x = 0.05 is 34% (105 K, 7 kOe).
Prolactin and Male Fertility: The Long and Short Feedback Regulation
M. K. Gill-Sharma
International Journal of Endocrinology , 2009, DOI: 10.1155/2009/687259
Abstract: In the last 20 years, a pituitary-hypothalamus tissue culture system with intact neural and portal connections has been developed in our lab and used to understand the feedback mechanisms that regulate the secretions of adenohypophyseal hormones and fertility of male rats. In the last decade, several in vivo rat models have also been developed in our lab with a view to substantiate the in vitro findings, in order to delineate the role of pituitary hormones in the regulation of fertility of male rats. These studies have relied on both surgical and pharmacological interventions to modulate the secretions of gonadotropins and testosterone. The interrelationship between the circadian release of reproductive hormones has also been ascertained in normal men. Our studies suggest that testosterone regulates the secretion of prolactin through a long feedback mechanism, which appears to have been conserved from rats to humans. These studies have filled in a major lacuna pertaining to the role of prolactin in male reproductive physiology by demonstrating the interdependence between testosterone and prolactin. Systemic levels of prolactin play a deterministic role in the mechanism of chromatin condensation during spermiogenesis.
Application of Cox Proportional Hazards Model in Case of Tuberculosis Patients in Selected Addis Ababa Health Centres, Ethiopia
Kabtamu Tolosie,M. K. Sharma
Tuberculosis Research and Treatment , 2014, DOI: 10.1155/2014/536976
Abstract: Introduction. Tuberculosis (TB) is a chronic infectious disease and mainly caused by mycobacterium tuberculosis (MTB). It has been one of the major causes of mortality in Ethiopia. The objective of the study was to identify factors that affect the survival of the patients with tuberculosis who started treatment for tuberculosis. Methods. This was a retrospective study in six randomly selected health centres in Addis Ababa, Ethiopia. The data were obtained from medical records of TB patients registered from September 2012 to August 2013 and treated under directly observed treatment surgery (DOTS) strategy. Kaplan Meier plots, logrank tests, and Wilcoxon tests were used to assess the survival pattern. Cox proportional hazards model for multivariable analysis was discussed. Results. Out of the total 826 registered TB patients, 105 (12.71%) died during the study period and 712 (87.29%) were censored. Based on Kaplan Meier survival curves, logrank test, and Wilcoxon test, it was found that the patients had statistically significant differences in survival experience with respect to age, body weight at initiation of treatment, TB patient category, and HIV status. Multivariable Cox hazards regression analysis revealed that the covariates age, TB patient category, HIV, and age by HIV interaction were significant risk factors associated with death status in TB patients. Conclusion. Deaths of individuals with diseases especially HIV coinfected and nonnew TB cases were high. Therefore, this needs to strengthen the follow-up of patients with TB treatment from the day of anti-TB treatment initiation to completion days. 1. Introduction Tuberculosis (TB) is the leading cause of death from a single bacterial species among adults around the world. The World Health Organization (WHO) estimated that one-third of the world population is infected with Mycobacterium tuberculosis, with 9.4 million new cases and 1.3 million deaths in 2009 [1]. Reducing death, eliminating disease, and preventing the development of drug-resistant TB are the major goals of TB control [2]. TB-related death is often referred to as a TB control indicator [3]. Although the developed countries in Europe and North America have well-equipped treatment facilities and provide free and sufficient anti-TB drugs, treatment success rates there are still below WHO’s goal of 85%, which may be because of the relatively high death rates. In those countries, TB cases are found in the relatively higher age group and are associated with comorbidities [4]. In previous studies, even in developed countries with good
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