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Search Results: 1 - 10 of 7357 matches for " Rachana Gupta "
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Gap Functions and Error Bounds for Set-Valued Vector Quasi Variational Inequality Problems  [PDF]
Rachana Gupta, Aparna Mehra
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.812135
Abstract:
One of the classical approaches in the analysis of a variational inequality problem is to transform it into an equivalent optimization problem via the notion of gap function. The gap functions are useful tools in deriving the error bounds which provide an estimated distance between a specific point and the exact solution of variational inequality problem. In this paper, we follow a similar approach for set-valued vector quasi variational inequality problems and define the gap functions based on scalarization scheme as well as the one with no scalar parameter. The error bounds results are obtained under fixed point symmetric and locally α-Holder assumptions on the set-valued map describing the domain of solution space of a set-valued vector quasi variational inequality problem.
Nanocrystallization and Amorphization Induced by Reactive Nitrogen Sputtering in Iron and Permalloy
Rachana Gupta,Mukul Gupta
Physics , 2004, DOI: 10.1103/PhysRevB.72.024202
Abstract: Thin films of iron and permalloy Ni80Fe20 were prepared using an Ar+N2 mixture with magnetron sputtering technique at ambient temperature. The nitrogen partial pressure, during sputtering process was varied in the range of 0 to 100%, keeping the total gas flow at constant. At lower nitrogen pressures RN2<33% both Fe and NiFe, first form a nanocrystalline structure and an increase in nitrogen partail pressure results in formation of an amorphous structure. At intermediate nitrogen partial pressures, nitrides of Fe and NiFe were obtained while at even higher nitrogen partial pressures, nitrides themselves became nanocrystalline or amorphous. The surface, structural and magnetic properties of the deposited films were studied using x-ray reflection and diffraction, transmission electron microscopy, polarized neutron reflectivity and using a DC extraction magnetometer. The growth behavior for amorphous film was found different as compared with poly or nanocrystalline films. The soft-magnetic properties of FeN were improved on nanocrystallization while those of NiFeN were degraded. A mechanism inducing nanocrystallization and amorphization in Fe and NiFe due to reactive nitrogen sputtering is discussed in the present article.
Iron self-diffusion in FeZr/$^{57}$FeZr multilayers measured by neutron reflectometry: Effect of applied compressive stress
Mukul Gupta,Ajay Gupta,Sujoy Chakravarty,Rachana Gupta,Thomas Gutberlet
Physics , 2006, DOI: 10.1103/PhysRevB.74.104203
Abstract: Iron self-diffusion in nano-composite FeZr alloy has been investigated using neutron reflectometry technique as a function of applied compressive stress. A composite target of (Fe+Zr) and (57Fe+Zr) was alternatively sputtered to deposit chemically homogeneous multilayer (CHM) structure, [Fe75Zr25/57Fe75Zr25]10. The multilayers were deposited on to a bent Si wafer using a 3-point bending device. Post-deposition, the bending of the substrate was released which results in an applied compressive stress on to the multilayer. In the as-deposited state, the alloy multilayer forms an amorphous phase, which crystallizes into a nano-composite phase when heated at 373 K. Bragg peaks due to isotopic contrast were observed from CHM, when measured by neutron reflectivity, while x-ray reflectivity showed a pattern corresponding to a single layer. Self-diffusion of iron was measured with the decay of the intensities at the Bragg peaks in the neutron reflectivity pattern after thermal annealing at different temperatures. It was found that the self-diffusion of iron slows down with an increase in the strength of applied compressive stress.
Phase formation, thermal stability and magnetic moment of cobalt nitride thin films
Rachana Gupta,Nidhi Pandey,Akhil Tayal,Mukul Gupta
Physics , 2015,
Abstract: Cobalt nitride (Co-N) thin films prepared using a reactive magnetron sputtering process by varying the relative nitrogen gas flow (\pn) are studied in this work. As \pn~increases, Co(N), \tcn, Co$_3$N and CoN phases are formed. An incremental increase in \pn, after emergence of \tcn~phase at \pn=10\p, results in a continuous expansion in the lattice constant ($a$) of \tcn. For \pn=30\p, $a$ maximizes and becomes comparable to its theoretical value. An expansion in $a$ of \tcn, results in an enhancement of magnetic moment, to the extent that it becomes even larger than pure Co. Though such higher (than pure metal) magnetic moment for Fe$_4$N thin films have been theoretically predicted and evidenced experimentally, higher (than pure Co) magnetic moment are evidenced in this work and explained in terms of large-volume high-moment model for tetra metal nitrides.
Depletion of Forest Resources and Wildlife Population with Habitat Complexity: A Mathematical Model  [PDF]
Rachana Pathak
Open Journal of Ecology (OJE) , 2018, DOI: 10.4236/oje.2018.811034
Abstract: Nowadays, management and regulation of natural resources like agriculture, fisheries, forestry and wildlife is one of the popular topics in research. The evolution of humankind is largely dependent on the quality of the environment and the resources it provides; but numerous human-induced factors, and climate change may drastically alter the conditions of human sustainability. This paper deals with effect of numerous human-induced activities on the depletion of forestry resources and wildlife population with habitat complexity. A nonlinear mathematical model is proposed and analyzed. In modeling process, we assume that the growth rate of wildlife population wholly depends on forestry biomass. It is depleted by human-induced activities. Local stability analysis of the mathematical model along with the persistence of the system is checked by using theory of nonlinear ordinary differential equations and Butler-McGhee lemma. Analytical results obtained are justified numerically through numerical simulation. Important parameters are investigated and variation of variables with change in these parameters is determined.
HYPHENATED TECHNIQUE- A BOON TO ANALYTICAL WORLD
Rachana R. Joshi* Krishna R. Gupta and Shitalkumar S. Patil
International Journal of Pharmaceutical Sciences and Research , 2012,
Abstract: Traditional analytical approaches including HPLC (High-Performance Liquid Chromatograph), GC (Gas Chromatograph), UV (Ultraviolet) detection, etc., have become insufficient to effectively handle the growing number of challenges in analyses of species- specificity and sensitivity. Modern analytical technique referred to as hyphenated techniques, originate from the traditional use of molecule or element specific detection in electrophoresis or chromatography. Currently the most common techniques for trace element speciation include a combination of separation technique coupled with a detection technique that is more sensitive. Earlier such hyphenated techniques were the coupling of separation of a special sample preparation off-line and later adding a detection technique. Presently, the hyphenated technique is developed from the coupling of a separation technique (Chromatography) and an on-line spectroscopic detection technology. Hyphenated techniques combine chromatographic and spectral methods to exploit the advantages of both. Chromatography produces pure or nearly pure fractions of chemical components in a mixture. Spectroscopy produces selective information for identification using standards or library spectra. These hyphenated techniques offer shorter analysis time, higher degree of automation, higher sample throughput, better reproducibility, reduction of contamination because it is a closed system, Enhanced combined selectivity and therefore higher degree of information. The remarkable improvements in hyphenated analytical methods over the last two decades have significantly broadened their applications in the analysis of biomaterials, especially natural products. In this article, recent advances in the applications of various hyphenated techniques, e.g., GC-MS, LC-MS, LC-FTIR, LC-NMR, CE-MS, etc. in the context of pre-isolation analyses of crude extracts or fraction from various natural sources, isolation and on-line detection of natural products, chemotaxonomic studies, chemical fingerprinting, quality control of herbal products, dereplication of natural products, and metabolomic studies are discussed with appropriate examples.
Formation of iron nitride thin films with Al and Ti additives
Rachana Gupta,Akhil Tayal,Mukul Gupta,Ajay Gupta,M. Horisberger,J. Stahn
Physics , 2011, DOI: 10.1063/1.4718579
Abstract: In this work we investigate the process of iron nitride (Fe-N) phase formation using 2 at.% Al or 2 at.% Ti as additives. The samples were prepared with a magnetron sputtering technique using different amount of nitrogen during the deposition process. The nitrogen partial pressure (\pn) was varied between 0-50% (rest Argon) and the targets of pure Fe, [Fe+Ti] and [Fe+Al] were sputtered. The addition of small amount of Ti or Al results in improved soft-magnetic properties when sputtered using \pn $\leq$ 10\p. When \pn is increased to 50\p non-magnetic Fe-N phases are formed. We found that iron mononitride (FeN) phases (N at% $\sim$50) are formed with Al or Ti addition at \pn =50% whereas in absence of such addition \eFeN phases (N\pat$\sim$30) are formed. It was found that the overall nitrogen content can be increased significantly with Al or Ti additions. On the basis of obtained result we propose a mechanism describing formation of Fe-N phases Al and Ti additives.
Conservation of Forestry Biomass with the Use of Alternative Resource  [PDF]
Manju Agarwal, Rachana Pathak
Open Journal of Ecology (OJE) , 2015, DOI: 10.4236/oje.2015.54009
Abstract: The effect of the alternative resource and time delay on conservation of forestry biomass is studied by considering a nonlinear mathematical model. In this paper, interaction between forestry biomass, industrialization pressure, toxicant pressure and technological effort is proposed and analysed. We find out the critical value of delay and observe that there is Hopf bifurcation. Using the normal form theory and the center manifold theorem, we determine the stability and direction of the bifurcating periodic solutions. Numerical simulations are given to illustrate the analytical results.
Enabling Access to Welfare Services - the Place of Social Solidarity and Dialogue
Patni, Rachana
Social Work and Society , 2007,
Abstract: The welfare state in the UK presents immigrant communities with a set of institutions, which are potentially new and unknown. What is the best way to ensure that the questions of access to the welfare institutions are best managed? Trusting, understanding and feeling solidarity with the welfare state will obviously help with this problem. In order to shed light on this phenomenon, this paper presents a qualitative exploratory study dealing with elements of solidarity as perceived by members of the South Asian Community in the UK. Six indepth interviews with South Asian first generation immigrants who had never experienced mental health problems were conducted. They were asked questions about who their support networks would be in the event of them experiencing mental health problems. The thematic analysis of the interviews suggests that the respondents believed that solidarity and support ties are found to be present in families, within the south Asian community and also with welfare institutions. It is concluded that there although things are far from perfect, assimilation and integration based on dialogue is an observable positive aspect of mental health service provision in the UK.
Non-Communicating inactive rudimentary horn of the uterus presenting with dysmenorrhoea—a case report of successful laparoscopic excision  [PDF]
Rachana Dwivedi, Keerthi Perera, Padma Eedarapalli
Open Journal of Obstetrics and Gynecology (OJOG) , 2011, DOI: 10.4236/ojog.2011.14041
Abstract: Uterine developmental abnormalities can cause both obstetric and gynaecological complications. Non-functioning rudimentary uterine horn is a rare cause of dysmenorrhoea which usually starts after menarche. Cases with lateral/inferior arrangement of blood supply to the functioning rudimentary horn and lapascopic removal have been described in literature. Ours is a unique case of non-functioning rudimentary horn with an unusual medial arrangement of vasculature successfully treated by laparoscopic excision. We also present a brief review of the literature. The patient presented with irretractable dysmenorrhoea despite hormonal manipulation and analgesics. Following the diagnosis using laparoscopy and hysteroscopy and MRI, the left sided non-communicating rudimentary horn with inactive endometrium was removed laparoscopically. Her symptoms were resolved and this was followed by successful pregnancies. Diagnosis of rudimentary horn with inactive endometrium is difficult. Ultrasound is unreliable. MRI, 3D CT scan and 3D ultrasound are gaining popularity. Accurate, prior identification of the type using laparoscopy and hysteroscopy if necessary is essential. This helps in surgical planning. The laparoscopic approach is increasingly being used to resect these horns due to its safety and merits.
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