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Search Results: 1 - 10 of 494930 matches for " M. B. Lekala "
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Laser Surface Alloying of 316L Stainless Steel with Ru and Ni Mixtures
M. B. Lekala,J. W. van der Merwe,S. L. Pityana
International Journal of Corrosion , 2012, DOI: 10.1155/2012/162425
Abstract: The surfaces of AISI 316L stainless steel were laser alloyed with ruthenium powder and a mixture of ruthenium and nickel powders using a cw Nd:YAG laser set at fixed operating parameters. The microstructure, elemental composition, and corrosion characteristics of the alloyed zone were analyzed using optical and scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and corrosion potential measurements. The depth of alloyed zone was measured using the AxioVision program and found to be approximately 1.8?mm for all the alloyed specimens. Hardness profile measurements through the surface-substrate interface showed a significant increase from 160?HV for the substrate to a maximum of 247?HV for the alloyed layer. The sample laser alloyed with 80?wt% Ni-20?wt% presented the most noble corrosion potential of ?V and the lowest corrosion current density . 1. Introduction Minor additions of ruthenium to the bulk volume of steels resulted in a significant improvement of corrosion resistance in many reducing environments [1]. Ruthenium modified alloys possesses properties which render them candidate alloys to replacing the expensive nickel-based alloys which are currently used in more aggressive corrosion environments [2]. However, owing to the high-cost associated with ruthenium, bulk alloying is currently not a feasible means, although opportunities to explore the method exist. For instance, Streicher [3] observed a synergistic benefit when ruthenium and nickel were added together to steels. This observation offers an opportunity to reduce the amount of ruthenium per bulk volume added in the alloying process, yet presents significant improved corrosion resistance. Thus, minor additions of ruthenium together with nickel present an economically sound approach of modifying corrosion properties of alloys. Furthermore, since corrosion is a surface phenomenon, an equally cost-effective approach is to add these only on the surface, where protection is most required. Laser surface modification techniques have been extensively studied for selective improvement of surfaces for wear, hardness, and corrosion [4–7]. The laser surface alloying technique is particularly applicable in cases where a change in the chemical composition and microstructure of the surface is required. The laser surface alloying technique enables external alloying elements to be added into the bulk material via a laser generated melt pool. Generally, the external alloy material is either preplaced on the desired surface of the substrate or fed into the melt pool. The alloy
Three dimensional bosonic cluster states of Efimov character near the unitary
M. L. Lekala,B. Chakrabarti,S. K. Haldar,G. J. Rampho
Physics , 2015,
Abstract: We study three-dimensional bosonic cluster interacting through van der Waals potential at large scattering length. We use Faddeev-type decomposition of the many-body wave function which includes all possible two-body correlations. At large scattering length, a series of Efimov-like states appear which are spatially extended and exhibit the exponential dependence on the state number. We also find the existence of generalized Tjon lines for $N$- body clusters. Signature of universal behaviour of weakly bound clusters can be observed in experiments of ultracold Bose gases.
A correlated basis approach for trapped bosons with very large particle number and the validity of shape independent approximation
M. L. Lekala,B. Chakrabarti,T. K. Das,G. J. Rampho,R. M. Adam,S. K. Haldar
Physics , 2014,
Abstract: We study the ground state and the low-lying excitations of interacting Bose gas trapped in an isotropic harmonic potential for very small ($N \sim 3$) to very large particle number ($N \sim 10^7$). We use the correlated two-body basis function and shape dependent van der Waals interaction in our many-body calculation. We investigate the effect of inteatomic correlation and the accuracy of Gross-Pitaevskii equation. We present an exhastive study of the validity of the shape independent approximation (SIA) for wide range of particle number. Our calculated ground state energies are well comparable with the modified Gross-Pitaevskii (MGP) results which reestablishes the shape-independent property of dilute BEC for wide range of particle number starting from very few to few million. We calculate several low-lying excitations for large particle limit and compare its asympototic behaviour with the hydrodynamic model~\cite{Stringari, Dalfovo}.
Triatomic Molecular Systems and Three-body forces: The Ar_3 case
M. L. Lekala,S. A. Sofianos
Physics , 2004, DOI: 10.1063/1.1932952
Abstract: We performed bound state calculations to obtain the first few vibrational states for the Ar_3 molecular system. The equations used are of Faddeev-type and are solved directly as three-dimensional equations in configuration space, i.e. without resorting to an explicit partial wave decomposition. In addition to realistic pairwise interactions, we employ long range three-body forces. Our results are in good agreement with those obtained by other methods based on partial wave expansion and show a significant contribution of the three-body forces (>10%) to the binding energy and thus their inclusion is, in general, warranted in studying similar triatomic systems.
E-mail Communication for Provisional Sentence Summons
Roy Samuel Lekala
Journal of International Commercial Law and Technology , 2011,
Abstract: Traditional rules of evidence deny the admissibility of data messages on the mere ground that it is digitised. The South African Electronic Communication and Transaction Act (ECT) was enacted to enable the courts to admit data messages. South African legislation in this regard has followed a similar approach taken by the United Kingdom, the United States, Canada and the Model law. The use of electronic documents as evidence in court initially posed a number of conceptual challenges to the traditional statutory and common law in South Africa. On a close reference to provisional sentence summons in civil courts, South Africa has not yet amended the rules of civil practice to accommodate modern technology, for example, electronic discovery. The success of provisional sentence summons as one of the civil procedures to recover a debt is highly dependent on the liquidity of a document. Clearly, the authors of the definition of a liquid document may not have anticipated the development of technology to the extent that the traditional paper can be replaced completely by the electronic document. This paper seeks to discuss the challenges that may be faced by the courts when determining the admissibility of e-mail communication for the purpose of granting provisional sentence in South African civil courts. The ECT Act excludes liquid documents such as cheques and promissory notes. Therefore the focus of the paper is to discuss whether the requirements of a liquid document for purpose of provisional sentence summons can be met through the use of an e-mail evidence and the challenging aspects in that regard.
Lecture Notes of Möbuis Transformation in Hyperbolic Plane  [PDF]
Rania B. M. Amer
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.515215
Abstract:

In this paper, I have provided a brief introduction on M?bius transformation and explored some basic properties of this kind of transformation. For instance, M?bius transformation is classified according to the invariant points. Moreover, we can see that M?bius transformation is hyperbolic isometries that form a group action PSL (2, R) on the upper half plane model.

Petroleum Potentials of the Nigerian Benue Trough and Anambra Basin: A Regional Synthesis  [PDF]
M. B. Abubakar
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.51005
Abstract:

A review on the geology and petroleum potentials of the Nigerian Benue Trough and Anambra Basin is done to identify potential petroleum systems in the basins. The tectonic, stratigraphic and organic geochemical evaluations of these basins suggest the similarity with the contiguous basins of Chad and Niger Republics and Sudan, where commercial oil discovery have been made. At least two potential petroleum systems may be presented in the basins: the Lower Cretaceous petroleum system likely capable of both oil and gas generation and the Upper Cretaceous petroleum system that could be mainly gas-generating. These systems are closely correlative in temporal disposition, structures, source and reservoir rocks and perhaps generation mechanism to what obtains in the Muglad Basin of Sudan and Termit Basin of Niger and Chad Republics. They are very effective in planning future exploration campaigns in the basins.

Chemical Affinity and the Density of Energy Levels  [PDF]
M. B. Saikhanov
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.611149
Abstract: It is shown that the state of chemical equilibrium of a closed system corresponds to the minimum density of its energy levels.
Dynamic Monitoring and Optimization of Fault Diagnosis of Photo Voltaic Solar Power System Using ANN and Memetic Algorithm  [PDF]
B. Ganeshprabu, M. Geethanjali
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.711300
Abstract: Most of the photo voltaic (PV) arrays often work in harsh outdoor environment, and undergo various faults, such as local material aging, shading, open circuit, short circuit and so on. The generation of these faults will reduce the power generation efficiency, and when a fault occurs in a PV model, the PV model and the systems connected to it are also damaged. In this paper, an on-line distributed monitoring system based on XBee wireless sensors network is designed to monitor the output current, voltage and irradiation of each PV module, and the temperature and the irradiation of the environment. A simulation PV module model is established, based on which some common faults are simulated and fault training samples are obtained. Finally, a memetic algorithm optimized Back Propagation ANN fault diagnosis model is built and trained by the fault samples data. Experiment result shows that the system can detect the common faults of PV array with high accuracy.
Opening up das Schloβ: Creating Room for Thinking by Combining the Territorial Cohesion Discourse and the Debate on the European Union Polity  [PDF]
B. M. Hissink Muller
Art and Design Review (ADR) , 2016, DOI: 10.4236/adr.2016.43011
Abstract: To widen the debate about territorial cohesion, one can have a look at political science. We can namely critique the territorial cohesion discourse’s exclusion of reasoning about the political by showing the relevance of the simultaneous debate on the European Union polity. It thereby also comes forward that the concept’s power practices illustrate the bureaucratic, multi-level, polycentric, and network governance in flux that characterizes this polity. The territorial cohesion discourse might then exemplify how this opaque organization of governing leads to and is made possible by an associated form of expertise, which raises new questions on the role of social and spatial science in our society.
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