Archives-June 2014

The increased demand for the development of certain materials to be used in aerospace, military and medical industries justifies the execution of an extensive investigation to enhance the properties of such materials, especially the shape memory alloys (SMAs). Copper based SMAs are constantly receiving wide attention due to their low cost and important applications. This work is an attempt to enhance the fatigue life of CuZnAl shape memory alloys. A powder metallurgy technique was adopted to prepare samples. Alloying elements such as vanadium, nickel and germanium were used to improve the mechanical properties. Porosity, SEM, EDS, microhardness, compression and fatigue tests were conducted. Alloying with (0.4%wt.V) results in a significant increase in ultimate compressive strength of (33.6 %) in comparison with the reference sample. The reference (control) sample in this work has a substantial increase in ultimate compressive strength (100%) in comparison with a previously reported value in the literature. A microhardness test supports the ultimate compressive strength result and yields an improvement of (39%). These improvements are reflected positively on the fatigue behavior. The endurance limit of alloyed sample was improved by a factor of (23.3 %) in comparison with the reference sample.

In this work, an experimental study was carried to obtain the fatigue damage for aluminum alloy, 2024-T4 under rotating bending loading and stress ratio R= -1. The experiments were done at RT(room temperature) ,25oC ,and 200oC. A modified damage stress model was suggested to predict the fatigue life under elevated temperature which has been formulated to take into account the damage at different load levels. The microstructure and hardness of aluminium alloy after fatigue-creep interaction testing have been investigated. Attention has been paid to the role of the microstructure and hardness on the fatigue-creep strength of aluminum alloy. It has been shown that, there is a little effect of microstructure in the cyclic response of aluminum alloy, while the hardness has a significant effect on the fatigue-creep strength. This is described numerically.

Critical Discourse Analysis (CDA) is a type of discourse-analytical research that primarily investigates the way ideology, dominance, social power abuse, and inequality are enacted, reproduced, and resisted by text and talk (and, more recently, through visual images, sound and other forms of semiosis in the social and political context. This entails a diversity of approaches to CDA research, drawing on various linguistic analytic techniques and different social theories, although all involve some form of close textual (and/or multimodal) analysis. This paper attempts to provide an overview of CDA, the multiple meanings of CDA, and the most important models of CDA, namely Critical Linguistics and Social Model, Relational-Dialectic Model, Socio-cognitive Model, and Discourse-Historical Model.

In today's dynamic environment, proper strategies are not enough for companies and they should also be able to work in harmony with their environment. Innovation is one of the factors that allow companies to achieve sustainable competitive advantage through appropriate leadership style and knowledge absorptive capacity. The purpose of this study was to investigate the intermediary role of knowledge absorptive capacity between transactional leadership style and innovation. The population of the study included medium and large-scale manufacturing companies in the industrial estates of Mashhad County. The data were collected by means of a questionnaire. Structural equation modeling and partial least squares were used for data analysis. The results of the analyzing the questionnaires distributed among the sample population - 82 senior managers of companies - showed that there was a significant and positive relationship between transactional leadership and knowledge absorptive capacity as well as knowledge absorptive capacity and organizational innovation. Therefore, the significance of the intermediary role of knowledge absorptive capacity was confirmed.

In this paper we introduce the variant of domination called s- domination for semigraphs. The concept of s- domination is stronger than the concept of domination in semigraphs. We prove that the s- domination number of a semigraphs does not increase when a vertex is removed in a semigraphs. This is unlike in the case of domination. We also consider maximal independent sets in semigraphs and observe that they are exactly independent s- dominating sets in semigraphs. We prove some related results.

The Fourier transform infrared (FT-IR) and FT-Raman of 2-Amino thiazole (2-AT) have been recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been investigated with the help of ab initio and density functional theory (DFT) methods. The assignments of the vibrational spectra have been carried out. The optimized geometric bond lengths and bond angles obtained by computation show good agreement with experimental data of the relative compound. The computed parameters also show good agreement with experimental data. The calculated HOMO and LUMO energies also show that charge transfer occurs within the molecule. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the ?* and ?* antibonding orbital and second order delocalization energies E(2) confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. Finally the calculations results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Community policing is an effort between the security agents and the community that identifies and solves community problems such as insecurity issues. This paper thus discusses the challenges facing the local private security guards toward enhancing community policing. The study found that poor working conditions, poor pay, lack of recognition from the public, inadequate working facilities, and poor communication channels were among the major challenges facing private guards in Eldoret town. The study recommends that there is need for improving working conditions as well as communication.

Bulk single crystal of L-Valinium picrate (LVP) was successfully grown from aqueous solution by Sankaranarayanan -Ramasamy (SR) unidirectional growth method with dimensions of 12 mm diameter and 75 mm length. Single crystal X-ray diffraction studies and powder XRD analysis have been carried out to confirm the structure and perfection of the crystal. The optical absorption window and the cutoff wavelength of the LVP have been identified by UV–Vis–NIR studies. Photoluminescence studies indicate that the grown crystal has a green fluorescence emission. The mechanical asset of the grown crystal has been studied using Vicker’s microhardness tester. Dielectric studies have been carried out for the grown crystal and the results were discussed in detail.

State estimation in electrical distribution systems (EDSs) is an analyzing tool for estimating the state of it for close monitoring and controlling by distribution management system (DMS). In this paper, RESs integrated EDS’s state is estimated using the distribution system state estimation (DSSE) model. It is a minimization problem with equality and inequality constraints which describe the practical considerations of real time EDS. The objective of DSSE modeling and its minimization is to compute state variables. For minimizing the objective function of DSSE model Artificial Bee Colony (ABC) algorithm is used to estimate load and Renewable Energy Sources (RESs) output. The performance of the proposed work is evaluated on IEEE 33 bus test system using MATLAB working platform and compared with other evolutionary optimization algorithms.

This research was aimed at bio-ethanol production by fungi capable of producing cellulases and to convert pre-treated lingo-cellulosic material to fermentable sugars. The lingo-cellulosic material such as sugarcane bagasses, sugarcane leaves, rice husk or wheat bran were used as substrates. Fungi were isolated from soil samples collected from various regions. The pure cultures were screened for the ability to degrade cellulose. The fungi capable of cellulose production were identified as Trichoderma sp based on colony characters, microscopic observation and identification. The substrates were powdered and pretreated with fungal isolates using Mandels’ and Reese media. The substrates were used as a carbon source. Then optimization studies were carried out by using five bio-mass substrates at different pH, temperature and incubation period. Analysis was done by using Gas Chromatography. Sugarcane bagasses, Juice waste, Rice husk, Wheat bran, and Dry leaves were treated with Trichoderma isolates. Sugarcane bagasse and juice waste have shown highest concentrat ion of reducing sugars of 45.95 mg/g and 40.56 mg/g respectively and ethanol yield of 51.15 % and 46.5 % respectively. Dry leaves, Wheat bran and Rice husk have shown less reducing sugars of 33.32 mg/g, 30.32 mg/g, and 29.45 mg/g and ethanol yield 11.1 %, 7.15 %, and 6 % respectively as compared with sugarcane bagasse and juice waste.