April 2009
Estimated optimization parameters of arrayed waveguide grating (AWG) for C-band applications
In the present paper, we will investigate theoretically the basic design parameters of silica-based arrayed waveguide grating (AWG) in the C-band’s spectral range (from 1.528 to 1.56 μm). We have demonstrated theoretically that the minimum the diffraction order m, the maximum the number of the input/output wavelength channels, and the maximum the number of the arrayed waveguides. Also, we have investigated the...
April 2009
Comparative study of microwave assisted and conventional synthesis of novel 2-quinoxalinone-3-hydrazone derivatives and its spectroscopic properties
A series of novel quinoxalin-2(1H)-one-3-hydrazone derivatives, 2a - 8d were synthesized via condensation of 3-hydrazinoquinoxalin-2(1H)-one, 1, with the corresponding ketones under microwave irradiation. The microwave assisted reaction was remarkably successful and gave hydrazones in higher yield at less reaction time compared to conventional heating method. The chemical structures of the compounds prepared were...
April 2009
Inhibitive and adsorption properties of ethanol extract of Colocasia esculenta leaves for the corrosion of mild steel in H2SO4
Inhibitive and adsorption properties of ethanol extract of Colocasia esculenta for the corrosion of mild steel in H2SO4 were investigated using weight loss, hydrogen evolution and IR methods of monitoring corrosion. The results obtained indicates that ethanol extract of C. esculenta is a good inhibitor for the corrosion of mild steel in H2SO4 and its inhibitive action is attributed to its...
April 2009
Equilibrium, kinetic and thermodynamic studies on the adsorption of phenol onto activated phosphate rock
Phosphate rock being locally abundant and cheap material in Jordan can be easily activated to become a promising adsorbent for phenol removal from aqueous solution. The phosphate rock before and after activation was characterized using XRD and IR techniques. The effects of various experimental parameters, such as initial phenol concentration, temperature, pH, contact time and adsorbent dose on the adsorption extent were...
April 2009
Relationship between global solar radiation and sunshine hours for Calabar, Port Harcourt and Enugu, Nigeria
April 2009
Elemental analysis of rice husk ash using X – ray fluorescence technique
Rice husk ash is one of the most silica rich raw materials containing about 90 – 98% silica after complete combustion among the family of other agro wastes. Ash samples from rice husks of five different origins were prepared at two different temperatures, 500 and 1000oC, respectively and the ash content was evaluated at each temperature. The interestingly high percentage of silica (taking up from the soil during...
April 2009
Adaptive lifting based image compression scheme for narrow band transmission system
To enable wireless internet and other data services using mobile appliances, there is a critical need to support content rich cellular data communication, including voice, text, image and video. However mobile communication of multimedia content has several bottlenecks including limited bandwidth of cellular networks, channel noise and battery constraints of the appliances. In this paper an efficient adaptive data codec...
April 2009
Matrices of the thermal and spectral variations for the fabrication materials based arrayed waveguide grating (awg) devices
In the present paper, we have investigated the basic forms of the matrices of the thermal and spectral variations of the refractive-index (RI) for three different fabrication materials such as lithium niobate, polymethyl metha acrylate (PMMA) and silica-doped that are based arrayed waveguide grating (AWG) device depends on curve fitting program. Then, we are able to study the transmission spectrum characteristics of...
April 2009
Optimizing planting areas using differential evolution (DE) and linear programming (LP)
The application of differential evolution (DE) algorithm to a constrained optimization problem of irrigation water use is presented in this study. Irrigation water, amounting to 10 Mm3 is optimized to irrigate 2500 ha of land where 16 different crops are planted on different areas of land. The crops are assumed not rain-fed but depend only on irrigation water. The DE which is an evolutionary based optimization...
April 2009
Speed-sensorless, adjustable-speed induction motor drive based on dc link measurement
This paper presents a new control strategy for three-phase induction motor which includes speed and torque control loops and the current regulation thereby overcoming the limitation of volts per hertz control drives. For close-loop control, the feedback signals including the rotor speed, flux and torque are not measured directly but are estimated by means of an algorithm. The inputs to this algorithm are the...
April 2009
The effect of Hibiscus anthocyanins on 2, 4-dinitrophenylhydrazine-induced hepatotoxicity in rabbits
This study examines the effects of anthocyanin extract of the dried calyces ofHibiscus sabdariffa Linn on the 2, 4-dinitrophenylhydrazine (2, 4-DNPH)-induced toxic side effects in rabbits liver. The side effects of DNPH which include tissue lipid peroxidation and depletion of antioxidant defenses were induced in rabbits with a single intraperitoneal administration of the toxicant (28 mg kg-1 body weight) at...
April 2009
Assessment of foundry properties of steel casting sand moulds bonded with the grade 4 Nigerian acacia species (gum arabic)
Gum Arabic is a plant gum exuded from bark of some species of trees called acacia species. Nigeria produces four different grades of material. Nigeria, the second largest producer in the world has no registered commercial uses for it. This research investigated the viability of casting steel in sand moulds bonded with grade 4 Nigerian gum Arabic. Sand specimens bonded with the material were subjected to...
April 2009
Vertical profiles of winds and electric fields triggered by tropical storms - under the hydrodynamic concept of air particle
Contrary to popular understanding, tropical storms are not just weather events that can easily be described by ground - or space - based observations. Instead the phenomena are a combination of complex physical processes that occur under the accuracy of temperature and humidity conditions. The water vapour originally produced by high temperatures, serves as a source of energy that maintains tropical storms, since this...
April 2009
An analytical expression for arbitrary derivatives of Gaussian functions exp(ax2)
In this study, an analytical expression for the arbitrary derivatives of Gaussian function is developed. Using this analytical expression developed within Rodrigues representation, an alternative expression is presented for the Hermite functions. With the help of the expression presented here the Hermite functions can easily be estimated. Key words: Arbitrary derivatives, Gaussian...
April 2009
FDTD studies of EM field enhancement in silver nano cylinders arranged in triangular geometry
Metallic nano structures exhibit interesting optical properties due to the coupling of surface plasmon resonances with the electromagnetic fields. Metal nano particles exhibit dramatic field enhancement in the vicinity of the nano particle which can be further increased by near field coupling between closely spaced particles. In this paper, we study a system made of 3 nano cylinders placed at the vertices of an...
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