bluuebunny/crossref_metadata_2025 huggingface dataset:
Employment of Some Parameters to Enhance Laser-Drilling of Aluminum
Authors: Hamadi Oday A.
Published: May 2017

In this work, some parameters affecting drilling of aluminum samples by a pulsed Nd:YAG laser were studied. These parameters are multi-pulses irradiation, controlling sample temperature, low-pressure ambient and application of electric field on the sample. Results presented in this work explained that these parameters can enhance drilling process throughout increasing hole depth in aluminum samples at the same laser energy used for irradiation.
Fabric Preserving and Fabric Destroying Dolomitization: A case of Seawater Dolomitization
Authors: Al-Langawi Alham Jassim
Published: May 2017

This study is based on field, petrographic and geochemical investigations of Hajar Supergroup autochthonous rocks: Ruus Al Jibal Group- Musandam Peninsula, and Akhdar Group- Jebel Akhdar, Oman and U.A.E., and para-autochthonous Maqam Formation-Sumeini Group-Jebel Sumeini-U.A.E.  Petrographic evidence indicates that the rocks were deposited in a shallow marine shelf environment, particularly tidal flat, lagoon, reef, back-reef and shoal environments that were part of the Arabian Platform during Permian and Triassic times. However, they are almost entirely dolomitized and the rocks show different petrographic features ranging from perfect preservation of original texture by mimetic dolomitization to complete obliteration and destruction of the original limestones giving rise to inequicrystalline and equicrystalline fabrics.  Dolomites analyzed by geochemical methods were categorized on the basis of textural variations; crystal size, shape and impurity or inclusion distribution within crystals, and whether these crystals are found as rock forming (replacive) or cements. The dolomites display variations in stoichiometry, ordering and trace element concentrations indicating differences in dolomitizing fluid chemistry and recrystallization stages that prevailed through time. It indicates also that although dolomitization is pervasive, dolomites are petrographically and chemically immature. All the petrographic and geochemical evidence strongly indicates seawater and/or mixing zone dolomitization which may have been initiated soon after deposition of the host sediments.  Rocks showing preservation of allochems as well as the marine cements by mimetic dolomite crystals, suggest that dolomitization was early (at shallow depths) with very active marine-water circulation and occurred in a relatively short time.  Evidence from crystalline dolomites indicates several crystallization events at shallow burial depths, under marine waters modified by increased temperature and mixing probably with evaporitic brines. The only fluid capable of early dolomitization in the case of the Oman Mountains dolomites was warm seawater from the Tethys Ocean which was circulating in the subsurface. KEYWORDS:
he Direction of Spontaneous Magnetisation of Lanthanide Ions at a Site of Cubic Symmetry
Authors: Carboni C. , Al-Abry E. , Arafin S.
Published: May 2017

The zero temperature direction of spontaneous magnetisation of lanthanide ions at a site of cubic symmetry is investigated as a function of the electrostatic and magnetic interactions. For all the values of J between J = 3 and J = 8, two-dimensional diagrams giving the orientation of spontaneous magnetisation are obtained as a function of the parameters R representing the relative strength of the magnetic to electrostatic interaction and the parameter x representing the relative strength of the fourth to the sixth order terms in the crystal field. The boundaries between regions of the parameter space with different directions of spontaneous magnetisation are investigated. It is found that at some boundaries there is a gradual rotation of the direction of spontaneous magnetisation and that at other boundaries there is a sudden change of orientation of spontaneous magnetisation at a critical value of the (R,x) parameters. Two types of behaviour are observed when there is a critical value of (R,x). There are boundaries where there is at the critical value a degenerate plane in which all the orientations can be direction of spontaneous magnetisation and some boundaries where two different principal crystallographic axes can be direction of spontaneous magnetisation at the critical value. In the latter case there is a region near the boundary where an unstable equilibrium orientation for the magnetisation can be found.
A Procedure to Correct Errors in Depth Estimation from Slope Hale Slope Method
Authors: Al-Rawi Fitian R. , Al-Rahim Ali M.
Published: May 2017

The novel method named slope half slope for depth estimation of the causative magnetic field proposed by Peters (1949) has been investigated to determine the possible percent errors in depth estimation to magnetic sources situated at different latitudes. A sequence of models represented by thick dykes with various depths and with different values of field inclination (0 to 90°) has been used to estimate the percentage errors for the different inclination values. A procedure to correct the errors in depth estimate has been discussed. The calculated percent errors range between positive and negative values for the same angle of inclination at various depths. This raises difficulties to use a formula concerning the factor to adjust the estimated depths and to overcome this problem. Therefore, a new approach has been adopted to correct the estimated depth values. A relationship between the horizontal distance at the tangential point and center of the maximum slope with the actual and estimated depths is found. Two straight lines are plotted from this relation and they are intersected at a certain point for each inclination value. The location of this point defines whether the difference between the actual and the estimated depth values will be added to or subtracted from the estimated depth to get the actual depth. In real depth determination, the correct value is determined by defining the intersect point between the estimated depth and the horizontal distance and then calculating the difference from the actual slope line for the assigned inclination angle. Each inclination angle has its own relation and intersected point that can be used to determine the actual depth.
Action Plan for Monitoring, Mitigation and Management of Harmful Algal Blooms in the Coastal Waters of Oman
Authors: AlKindi A.Y.A , Al-Ghelani H.M.H. , Amer S. , Al-Akhzami Y.K
Published: May 2017

The Gulf of Oman, an ecologically and economically rich ecosystem, is frequently impacted by occurrences of harmful algal blooms. Recent studies indicate an increase in the number of causative species and harmful impacts. Many red tide incidents in Oman have been found leading to hypoxia. The frequent bloom forming species here are Karenia selliformis, Nitzschia pungens, Prorocentrum arabianum and Trichodesmium erythraeum. We review work carried out in this area, and we propose here a Management Action Plan for not only an effective monitoring system for harmful algal blooms (HABs), but also mitigation of their adverse impacts and rapid response system.
Studies of Surface Area and Pore Structure on Portland Cement Produced in Bajil and Amran, Yemen
Authors: Saad A.M. , Saleh Abdul-Basit A. , Al-Kadri Fatima A. , Babaqi Abdulla S. , Basissa Abdulla A. , El-Enein S.A. Abo
Published: May 2017

Portland cement pastes of various porosities were prepared using water/cement ratios of 0.30, 0.35, 0.40, 0.45, 0.50 and 0.55; and were hydrated for various time intervals ranging from 0.021 to 28 days.  Pore structure and VL–t plots (plots of volume vs. thickness) of the hardened cement pastes were measured using nitrogen gas as the adsorbate. The results were found to be related to the mechanism of hydration as controlled by the pore system of the hardened pastes. Type ІІ adsorption isotherms of nitrogen were obtained for all hardened cement pastes. The adsorption-desorption isotherms indicated the existence of closed hysteresis loops for most of the investigated samples and in some other cases, these isotherms were fully reversible.
Stability and Persistence of Synchronization in a System with a Diffusive-Time-Lag Coupling
Authors: Wasike Adu A.M.
Published: May 2017

We study synchronization in the framework of invariant manifold theory for systems with a time lag.  Normal hyperbolicity and its persistence in infinite dimensional dynamical systems in Banach spaces is applied to give general results on synchronization and its stability.
Stability of The Synchronization Manifold in An All-To-All Time LAG- Diffusively Coupled Oscillators
Authors: Wasike Adu A.M.
Published: May 2017

we consider a lattice system of identical oscillators that are all coupled to one another with a diffusive coupling that has a time lag. We use the natural splitting of the system into synchronized manifold and transversal manifold to estimate the value of the time lag for which the stability of the system follows from that without a time lag. Each oscillator has a unique periodic solution that is attracting.
Integumentary Histology of the Amphibious Blenny, Isteblennius edentulus (Forester and Schneider, 1801)
Authors: Ba-Omar Taher , Al-Riyami Maisoon M.
Published: May 2017

The skin of the amphibious blenny, Istiblennius edentulus, was studied using both light and scanning electron microscopy. Rich vascularisation was found immediately below the epidermis and the dermis. Surface epithelial cells displayed microridges in a fingerprint-like pattern.  It was speculated that this increased surface area may aid in the adhesion of mucous secretions as well as to increase the surface area for gas exchange. The number of pores on the dorsal side (6.3x103 per mm2) was significantly higher than that on the ventral side (4.3x103 per mm2). The thickness of the skin on the dorsal side was measured at 31.6±10.0µm and that on the ventral side was 32.9 ± 7.8µm.
Screening and Purification of a Chymotrypsin Inhibitor from Entrolobium Saman Seeds
Authors: Maqtari Maher Ali. , Saad A.B. Mohamed.
Published: May 2017

A chymotrypsin inhibitor was isolated and purified from the seeds of Enterolobium saman  (Leguminaceae family) by extraction with 100 mM phosphate buffer, heat treatment, ammonium sulphate precipitation, ion-exchange chromatography on DEAEcellulose and filtration through Sephadex G-75. The final preparation appeared to be homogeneous by both chromatographic and electrophoretic analyses. ESCI had a molecular weight of about 17,890 and an isoelectric point of 5.8. ESCI inhibited bovine chymotrypsin at an inhibitor-enzyme molar ratio of 1:2. The inhibition mode of chymotrypsin inhibitor was competitive on bovine chymotrypsin. Investigation has been carried out on the complex formed between chymotrypsin and chymotrypsin inhibitor by physico-chemical methods. An apparent dissociation constant (Ki) of 9.05 X 10-8 M has been calculated for the complex. This enzyme-  inhibitor complex was isolated by gel filtration on Sephadex G-75 and a molecular weight of 43.000 was estimated for the complex. The inhibitor did not have any effect on other proteinases, such as papain, bromelin, elastase, α -amylase, trypsin and pepsin. The chemical modification of lysine residues indicated that –NH2  groups are not essential for the activity of ESCI toward chymotrypsin. The inhibitor was an acidic protein and was stable over a wide pH range of 2-12 and temperature range of 10o C-97o C.
Comparison of the Physiological age of Adult Resting Versus Flying Culex Quinquefasciatus (Diptera: Culicidae)
Authors: Roberts D.M.
Published: May 2017

Relatively little is known about the physiological age of resting mosquitoes. In this study, Culex quinquefasciatus Say had a similar proportion of males (75%) in the resting as in the flying population (76%), but among the females, there were significant differences between the physiological age of the resting and flying populations. The proportion of unfed  females (51%)  was significantly smaller  in the resting than in the flying female group (82%).  By contrast, in the resting group, there were much higher proportions of blood-fed (28% compared with 4%) and to a lesser extent gravid (21% compared with 14%) females. Of the blood-fed females, most of the resting individuals were freshly blood-fed. Both males and females entered the resting traps throughout the day (but none were collected after sunset), with the main peak around dawn. The flying population showed two circadian peaks: a larger peak at dawn and smaller peak after sunset. This indicates a different pattern from that shown in other studies and demonstrates the significant geographic variation within this pan-tropical species.
On the Existence of Evolutionary Learning Equilibriums
Authors: Choudhury Masudul Alam
Published: May 2017

The usual kinds of Fixed-Point Theorems formalized on the existence of competitive equilibrium that explain much of economic theory at the core of economics can operate only on bounded and closed sets with convex mappings. But these conditions are hardly true of the real world of economic and financial complexities and perturbations. The category of learning sets explained by continuous fields of interactive, integrative and evolutionary behaviour caused by dynamic preferences at the individual and institutional and social levels cannot maintain the assumption of closed, bounded and convex sets. Thus learning sets and multi-system inter-temporal relations explained by pervasive complementarities and  participation between variables and entities, and evolution by learning, have evolutionary equilibriums. Such a study requires a new methodological approach. This paper formalizes such a methodology for evolutionary equilibriums in learning spaces. It briefly points out the universality of learning equilibriums in all mathematical structures. For a particular case though, the inter-systemic interdependence between sustainable development and ethics and economics in the specific understanding of learning domain is pointed out.
A Superlinearly Convergent Penalty Method with Nonsmooth Line Search for Constrained Nonlinear Least Squares
Authors: Mahdavi-Amiri Nezam , Ansari Mohammad Reza
Published: May 2017

Recently, we have presented a projected structured algorithm for solving constrained nonlinear least squares problems, and established its local two-step Q-superlinear convergence. The approach is based on an adaptive structured scheme due to Mahdavi-Amiri and Bartels of the exact penalty method. The structured adaptation also makes use of the ideas of Nocedal and Overton for handling the quasi-Newton updates of projected Hessians and appropriates the structuring scheme of Dennis, Martinez and Tapia. Here, for robustness, we present a specific nonsmooth line search strategy, taking account of the least squares objective. We also discuss the details of our new nonsmooth line search strategy, implementation details of the algorithm, and provide comparative results obtained by the testing of our program and three nonlinear programming codes from KNITRO on test problems (both small and large residuals) from Hock and Schittkowski, Lukšan and Vlček and some randomly generated ones due to Bartels and Mahdavi-Amiri. The results indeed affirm the practical relevance of our special considerations for the inherent structure of the least squares.
A New Sparse Quasi-Newton Update Method
Authors: Cheng Minghou , Dai Yu-Hong , Diao Rui
Published: May 2017

Based on the idea of maximum determinant positive definite matrix completion, Yamashita proposed a sparse quasi-Newton update, called MCQN, for unconstrained optimization problems with sparse Hessian structures. Such an MCQN update keeps the sparsity structure of the Hessian while relaxing the secant condition. In this paper, we propose an alternative to the MCQN update, in which the quasi-Newton matrix satisfies the secant condition, but does not have the same sparsity structure as the Hessian in general. Our numerical results demonstrate the usefulness of the new MCQN update with the BFGS formula for a collection of test problems. A local and superlinear convergence analysis is also provided for the new MCQN update with the DFP formula.
CG Versus MINRES: An Empirical Comparison
Authors: Chin-Lung Fong David , Saunders Michael
Published: May 2017

For iterative solution of symmetric systems  the conjugate gradient method (CG) is commonly used when A is positive definite, while the minimum residual method (MINRES) is typically reserved for indefinite systems. We investigate the sequence of approximate solutions  generated by each method and suggest that even if A is positive definite, MINRES may be preferable to CG if iterations are to be terminated early. In particular, we show for MINRES that the solution norms  are monotonically increasing when A is positive definite (as was already known for CG), and the solution errors  are monotonically decreasing. We also show that the backward errors for the MINRES iterates  are monotonically decreasing.
Local Projection Stabilization Method for Incompressible Flow Problems
Authors: Essefi A.M. , Nafa K.
Published: May 2017

We analyze Local Projection Stabilization (LPS) methods for the solution of Stokes problem using equal order finite elements. We investigate their convergence, stability and accuracy properties. The resulting stabilized method is shown to lead to optimal rates of convergence for both velocity and pressure approximations. We distinguish two classes of LPS methods: one-level and two-level methods. Numerical examples using bilinear interpolations are presented to validate the analysis and assess the accuracy of both approaches.
First Steps in Mesh WiFi Network Design by Genetic Algorithm
Authors: Reed Martin B. , Nash Stuart
Published: May 2017

Given a mesh of wireless nodes for WiFi customers covering a city district, we describe a genetic algorithm-based approach to the problem of selecting a small fixed number of nodes as gateways to the internet, and linking the remaining nodes to the gateways either directly or by 'hopping', to create an efficient mesh network structure. The algorithm uses a modification of k-means clustering to allocate nodes to gateways.
A Wavelet-based Energetic Approach for the Analysis of Electroencephalogram
Authors: Siddiqi Abul Hasan , Sevindir Hulya Kodal
Published: May 2017

Electroencephalography (EEG) is the recording of electrical activity along the scalp produced by the firing of neurons within the brain. The main application of EEG is in the case of epilepsy, as epileptic activity can create clear abnormalities on a standard EEG study. EEG signals, like many biomedical signals, are highly non-stationary by their nature. Wavelet analysis has found a prominent position in the investigation of biomedical signals for its ability to analyze such signals, in particular EEG signals. Wavelet transform is capable of separating the signal energy among different frequency bands (i.e., different scales), achieving a good compromise between temporal and frequency resolution. The present study is an attempt at better understanding of the mechanism causing the epileptic disorder and accurate prediction of the occurrence of seizures. In the present paper we identify typical patterns of energy redistribution before and during a seizure using multi-resolution wavelet analysis.
An Annotated Checklist of the Mammals of Kuwait
Authors: Cowan Peter J.
Published: May 2017

An annotated checklist of the mammals of Kuwait is presented, based on the literature, personal communications, a Kuwait website and a blog and the author’s observations. Twenty five species occur, a further four are uncommon or rare visitors, six used to occur whilst another two are of doubtful provenance. This list should assist those planning desert rehabilitation, animal reintroduction and protected area projects in Kuwait.
Volatile Compounds of the Leaves and Flowers of Lavandula dhofarensis A.G. Miller
Authors: Williams John R. , Fatope Majekodunmi O. , Al-Kindy Salma M.Z. , Suliman Fakhr Eldin O. , Al-Saidi Salim H.
Published: May 2017

The leaves and flowers of Lavandula dhofarensis were collected from the Dhofar region of Oman and hydro-distilled to give low boiling volatiles, which did not condense at 10 oC.  The dichloromethane extract of the hydrosol was analyzed by GC/FID and GC/MS. Sixty four compounds were identified in the volatiles of the leaves, accounting for 78.7% of the total.  The major components were caryophyllene oxide (8.0%), germacrene (7.9%), spathulenol (7.8%), and b-caryophyllene (6.6%). Eighty six compounds were also identified in the volatiles of the leaves plus flowers, comprising 94.5% of the total. The major compounds were camphor (12.9%), viridiflorol (10.5%), a-terpinyl acetate (7.5%), valerenal (7.2%), a-gurjunene (5.6%), and spathulenol (5.5%). Compounds such as linalool, linalyl acetate, 1,8-cineole, and b-ocimene, which are usually found as the major components of lavender oils, were either absent or detected at low levels  (<0.1%) in the hydrosol of L. dhofarensis. This investigation showed that the fragrance essence of L. dhofarensis is different from the other Lavandula species. L. dhofarensisis is regionally endemic to wetter areas of Oman.
Ferrocenylethynyl - a versatile platform for new molecules to novel materials
Authors: Shah Hakikulla H. , Al-Belushi Rayya A. , Khan Muhammad S.
Published: May 2017

Ferrocenylethynyl is a key starting material for the synthesis of fascinating new molecules and novel functional materials. It combines the robust and redox-active ferrocene moiety with the rigid-rod ethynyl unit. The ferrocene center provides chemically and electrochemically switchable material properties whereas the ethynyl backbone facilitates electron delocalization along the molecule, yielding materials with the potential for a wide range of applications from sensors to bio-organometallics and pharmaceuticals, from catalysts to nonlinear optical materials, and from fuel additives to chelating agents. However, lifetime performances and costs still need to be optimized to make ferrocenylethynyl-based materials commercially competitive. Efficient synthetic methods are already in place which could play a key role in the progress of these materials. This review discusses the main approaches adopted in the synthesis of ferrocenylethynyl-based molecules and materials. Representative examples of each method are reported, highlighting its significant achievements together with the open issues and challenges to be faced by future researchers in this area.
Facile and Surfactant-Free Synthesis of Hierarchical ZnO Microstructures
Authors: Qi Kezhen , Wang Ruidan , Fu Jiaqi , Chen Ke , Zuo Chunying
Published: May 2017

Hierarchical ZnO crystals with flower-like microstructures were successfully synthesized via a facile hydrothermal route without using any surfactants. The morphology of these microstructures can be easily controlled by adjusting the pH of the reaction solution. The products were characterized by X-ray powder diffraction (XRD) and scanning electron microscope (SEM). Furthermore, a possible growth mechanism of ZnO hierarchical microstructures was proposed.
Hydromagnetic Boundary Layer Flow and Heat Transfer Characteristics of a Nanofluid over an Inclined Stretching Surface in the Presence of a Convective Surface: A Comprehensive Study
Authors: Rahman Mohammad M. , Al-Hatmi Mohammed M.
Published: May 2017

In this paper we investigate numerically the hydromagnetic boundary layer flow and heat transfer characteristics of a nanofluid using three types of nanoparticles (copper, aluminium oxide and titanium dioxide) having various shapes (spherical, cylindrical, arbitrary, etc) by considering three kinds of base fluids (water, ethylene glycol and engine oil) over a nonlinear inclined stretching surface, taking into account the effect of convective surface condition. Using similarity transformations, the governing nonlinear partial differential equations of the physical model are transformed into non-dimensional ordinary differential equations which are solved for local similar solutions using the very robust computer algebra software, Maple 13. The numerical simulation is carried out to investigate the role of the pertinent parameters on the flow and temperature fields as well as on the rate of heat transfer and on the rate of shear stress. The results show that the addition of nanoparticles to the base fluid may not always increase the rate of heat transfer. It depends significantly on the surface convection, type of base fluid and nanoparticles.  The finding of this study will open a gate for better understanding of nanofluid characteristics.
Projection of Polyhedra onto Coxeter Planes Described with Quaternions
Authors: Al-Ajmi Mudhahir , Koca Mehmet , Salasel Hashima Bait Bu
Published: May 2017

3-dimensional convex uniform polyhedra have been projected onto their corresponding Coxeter planes defined by the simple roots of the Coxeter diagram ,
Some Improved Estimators in Double Sampling Using two Auxiliary Variables
Authors: Ahmed Mohammad S.
Published: May 2017

Dash and Mishra [1] suggested an improved class of estimators without defining the optimum estimator. However, they gave the wrong Taylor’s series expression of their class of estimator and their minimum mean squared error expressions are also incorrect. Here we show that Ahmed et al.’s [2] class of chain estimators is more efficient than Dash and Mishra’s [1], with minimum mean squared error.
The Seroprevalence of Human Toxoplasmosis in Oman
Authors: Idris M.A. , Al-Jaedy S.S. , Al-Dhahry S.H.S.
Published: May 2017

The prevalence of Toxoplasma 1gG antibodies was studied in three age groups (children. blood donors and pregnant women) in Oman. The highest prevalence rate was shown by pregnant women (39.5%). followed by children (2l%) and lastly by blood donors ( I0. 5%). Prevalence rates were analyzed by age groups and showed no significant difference. Furthermore. a comparative sensitivity analysis between the three tests, ELISA 1gG. DA and MEIA Toxo 1gG was performed. There was no significant difference between them.
Ghost Crabs of Oman ( Crustacea : Brachyura :Ocypodidae)
Authors: Clayton D.A.
Published: May 2017

The sandy beaches of the coasts of Oman support five species of Ocypode ghost crabs.  Ocypode cordimanus is found on supra-littoral sand dunes while O. saratan O. rotundata, and O. platytarsis  occur on the open beaches. O. jousseamei is largely restricted to marine inlets or khawrs. The present records represent range extensions for all five species. The species composition of the Ocypode assemblages of Oman is unique and clearly distinct from that of either East Africa or India. A description of the Species. including at key for their identification is provided.
Filter Representation of Normal Lattice
Authors: Yallaoui B.
Published: May 2017

In this paper we will investigate the properties of normality lattices and their relationships to zero-one measures. We will establish necessary and sufficient conditions for lattices to be normal. These properties are then investigated in the case of separated lattices.
Antibacterial and Antifungal Activities of Cyanobacterial Strains Isolated from Hot Springs in Oman
Authors: Sherwani1 Neelam , Abed Raeid M.M. , Dobretsov Sergey , Mary Sheji
Published: May 2017

In this study, cyanobacterial microbial mats from five hot springs in Oman, namely Al Kasfah Rustaq, Al Thwara Nakhl, Al–Ali Hammam, Gala and Bowsher, were characterized using direct microscopy. Nine monoclonal cyanobacterial cultures were obtained and their extracts in butanol, dichloromethane (DCM) and hexane were screened for antibacterial and antifungal activities. Direct microscopy revealed the presence of 12 different unicellular and filamentous morphotypes, with different distribution in the various mats. Temperature seems to be one of the most important parameters that accounts for the differences in cyanobacterial composition of the mats. Cells of the nine isolates and their aqueous supernatants were subsequently extracted with butanol, DCM and hexane. Dried extracts were tested against nine bacterial (i.e. gram +ve Staphylococcus aureus, Bacillus subtilis and gram –ve, Escherichia coli, Klebsiella pneumoniae, Salmonella choleraesuis, S. enterica, Psuedomonas aeruginosa, Providencia stuartii, and  Acinetobacter calcoaceticus) and two fungal pathogens (Rhizoctonia solani and Pythium sp.). All isolates exhibited antibacterial and antifungal activities, which depended mainly on the type of cyanobacterial culture, type of solvent used and the pathogen tested. The highest antibacterial activity was observed in Phormidium species, and butanol was found to be the most appropriate solvent to extract bioactivity from these cyanobacterial species. The results of this study suggest that thermal springs in Oman harbor diverse types of cyanobacteria, which may constitute an important source of antibacterial and antifungal compounds. Further investigation is needed to purify these compounds and find their chemical compositions and modes of action.
Crystal Field Parameters and Optical Parameters of Nd3+ in Sodium Bismuth Silicate Glass
Authors: Thomas Vinoy , Sofin Ramakrishna P.G.P.S. , Allen Mathew , Thomas Hysen
Published: May 2017

Neodymium doped sodium bismuth silicate glasses were prepared by the melt quench technique. Optical absorption spectra of the Nd3+ion in the present glassy systems were recorded in the UV-Vis-NIR region. Taylor series expansion method was adopted for theoretical evaluation of various crystal field parameters such as the Slater-Condon (F2,F4,F6), spin orbit and Racah parameters (E1,E2,E3). Oscillator strength and electric dipole line strength of the observed transitions were evaluated with the help of Judd-Ofelt (JO) theory. Radiative transition probability (A), total radiative transition probability (At), radiative life time (trad), branching ratios (b) and integrated absorption (sa) cross section for stimulated emission between the meta stable state 4F3/2 and 4IJ ( J= 15/2,13/2,11/2 and 9/2) levels were calculated using JO parameters. Optical basicity of the glass was found to increase with the addition of  bismuth.
A Note on Using Partitioning Techniques for Solving Unconstrained Optimization Problems on Parallel Systems
Authors: Al-Baali Mehiddin , Triki Chefi
Published: May 2017

We deal with the design of parallel algorithms by using variable partitioning techniques to solve nonlinear optimization problems. We propose an iterative solution method that is very efficient for separable functions, our scope being to discuss its performance for general functions. Experimental results on an illustrative example have suggested some useful modifications that, even though they improve the efficiency of our parallel method, leave some questions open for further investigation.
A Priori Error Estimates for Mixed Finite Element Schemes for the Wave Equation
Authors: Karaa Samir
Published: May 2017

A family of implicit-in-time mixed finite element schemes is presented for the numerical approximation of the acoustic wave equation. The mixed space discretization is based on the displacement form of the wave equation and the time-stepping method employs a three-level one-parameter scheme. A rigorous stability analysis is presented based on energy estimation and sharp stability results are obtained. A convergence analysis is carried out and optimal a priorierror estimates for both displacement and pressure are derived.
Mapping Methods to Solve a Modified Korteweg-de Vries Type Equation
Authors: Krishnan Edamana. V.
Published: May 2017

In this paper, we employ mapping methods to construct exact travelling wave solutions for a modified Korteweg-de Vries equation. We have derived periodic wave solutions in terms of Jacobi elliptic functions, kink solutions and singular wave solutions in terms of hyperbolic functions.
Effects of Age, Breed and Sex on Haematological Parameters of Growing Omani Goat Breeds
Authors: I. Osman Nur El Huda , Al-Busaidi Rashid M. , Johnson Eugene H.
Published: May 2017

Sixty seven healthy growing goat kids of three Omani breeds, born and raised in Sultan Qaboos University Agricultural Experiment Station, were used to study the effects of age, breed and sex on haematological parameters. Blood samples were collected at several times from the first to 25 weeks to study the following parameters: Red Blood Cells (RBCs), White Blood Cells (WBCs), Packed Cell Volume (PCV), Haemoglobin (Hb), Mean Cell Volume (MCV), Mean Cell Haemoglobin Concentration (MCHC) and Mean Cell Haemoglobin (MCH). At birth, MCV and MCH levels were significantly higher in Batina (BAT) kids than both Jabal Akhdar (JA) and Dhofari (DOF), but there were no breed differences in the rest of the haematological values. There were significant breed differences in RBC, MCH, WBC, MCV at different ages, with Hb and PCV being highly significant at all ages. All blood parameters changed with time but showed different patterns in all breeds. There was no effect of sex on RBC, MCHC, PCV, Hb or WBC, but female kids had significantly higher MCH and MCV values at week 12. This study indicates that haematology parameters in Omani goat kids could be affected by age, breed and sex.
Nodulation of Medicago Sativa L. by Different Rhizobium Strains in the Sultanate of Oman
Authors: Elshafie A.E. , Victor R. , Al-Mugbali N.
Published: May 2017

Three native Rhizobium strains were isolated from Musandam. Buraimi and the Agricultural Experiment Station at Sultan Qaboos University in the Sultanate of Oman. An internationally known Rhizobium strain (TAI. 1373} was obtained from the Nitrogen Fixation for Tropical Agriculture I.egume Collection at the University of Hawaii. U.S.A-. for comparison. The different abilities of the strains to nodulate  Medicago sativa I. were investigated. Different plant parameters namely, the fresh and dry weights of the shoot (g/plant ). the number of nodules per plant and the nitrogenase  activity (u mole C2H2/sample/3hours) were measured. The results showed that the native Rhizobia were capable of nodulating M saliva. But inoculation with effective known strains such as TAL1373 enhanced nodulation.
Distributed Simulation of Open Cyclic Queuing Networks
Authors: Harous Saad
Published: May 2017

In this paper we present the results of an experimental performance study of distributed simulation of open cyclic queuing networks using a minor variation of the deadlock detection and recovery based algorithm of Chandy and Misra. One major part of this study is to determine the effect of overhead on distributed simulation. Moreover, we measure certain refined notions of ideal speedup ratio." These ratios are more refined than just the number of processors in the sense that they capture the potentially achievable speedups of distributed simulation more closely.
IGBT Based DC/DC Converter
Authors: Akherraz M.
Published: May 2017

This paper presents an in-depth analytical and experimental investigation of an indirect DC-DC converter. The DC-AC conversion is a full bridge based on IGBT power modules, and the AC-DC conversion is done via a high  frequency AC link and a first diode bridge. The AC link, which consists of snubbing capacitors and a variable air-gap transformer, is analytically designed to fulfill Zero Voltage commutation requirement. The proposed converter is simulated using PSPICE and a prototype is designed built and tested in the laboratory. PSPICE simulation and experimental results are presented and compared.
On the Roles of Interatomic Interactions and Coordination Numbers on Einstein Temperatures of 3D Transition Metals
Authors: Khaleque M.A. , Bhuiyan G.M. , Rashid RI.M.A , Rahman S.M.M
Published: May 2017

We have investigated the roles of the coordination numbers and interatomic interactions on Einstien temperatures 0e for a number of bee 3d transition metals. We have employed a few of the popular transition metal pseudopotentials in the Calculations aiming at a comparative survey of the roles of these pseudopotentials on the Einstein temperature; the role of the neighboring atoms on the latter emerges as a by-product of the calculations.
Using Switching Linear Systems to Reach a Prespecified Traget
Authors: Benmerzouga A.
Published: May 2017

A conventional enumeration approach, and a new approach for the solution of the control of switched linear systems with input constraints are presented. The main objective in this work is to determine control sequences {U‘(K), i -l , M and  k –O, l, ….., N - l} which transfer the system from a given initial state X(0) to a specific target state Xt, (or to be as close as possible). Considering both the conventional enumeration and the new approach, extensive computer simulations are performed using the discrete time system obtained by sampling (or discretizing) a continuous system. The new approach is found to be more efficient than the enumeration one in terms of computations and computer storage and performs adequately under a variety of input data The procedure developed can be generalized and used to solve several versions of the switching control problem. In particular, a procedure using a quadratic cost function (distance) is given for problems with time-invariant coefficients.
A Comparative Analysis and Prediction of Traffic Accident Causalities in the Sultanate of Oman using Artificial Neural Networks and Statistical methods
Authors: Ali Galal A. , Al-Alawi Saleh M. , S.Bakheit Charles
Published: May 2017

Traffic accidents are among the major causes of death in the Sultanate of Oman This is particularly the case in the age group of I6 to 25. Studies indicate that, in spite of Oman's high population-per-vehicle ratio, its fatality rate per l0,000 vehicles is one of the highest in the world. This alarming Situation underlines the importance of analyzing traffic accident data and predicting accident casualties. Such steps will lead to understanding the underlying causes of traffic accidents, and thereby to devise appropriate measures to reduce the number of car accidents and enhance safety standards. In this paper, a comparative study of car accident casualties in Oman was undertaken. Artificial Neural Networks (ANNs) were used to analyze the data and make predictions of the number of accident casualties. The results were compared with those obtained from the analysis and predictions by regression techniques. Both approaches attempted to model accident casualties using historical  data on related factors, such as population, number of cars on the road and so on, covering the period from I976 to 1994. Forecasts for the years 1995 to 2000 were made using ANNs and regression equations. The results from ANNs provided the best fit for the data. However, it was found that ANNs gave lower forecasts relative to those obtained by the regression methods used, indicating that ANNs are suitable for interpolation but their use for extrapolation may be limited. Nevertheless, the study showed that ANNs provide a potentially powerful tool in analyzing and forecasting traffic accidents and casualties.
Constructing Node-Disjoint Routes in K-Ary N-Cubes
Authors: Day Khaled , Al-Ayyoub Abdel Elah
Published: May 2017

In this paper, a method for constructing node-disjoint (parallel) paths in k-ary n-cube interconnection networks is described. We start by showing in general how to construct parallel paths in any Cartesian product of two graphs based on known paths in the factor graphs. Then we apply the general result to build a complete set of parallel paths (i.e., as many paths as the degree of the network) between any two nodes of a k-ary n-cube which can be viewed as the Cartesian product of complete graphs. Each of the constructed paths is of length at most 2 plus the minimum distance between the two nodes. These parallel paths are useful in speeding-up the transfer of large amounts of data between two nodes and in offering alternate routes in cases of faulty nodes.
A Generalization of the Hypergeometric Distribution
Authors: Elsheikh E.K. , Benmerzouga A.
Published: May 2017

In this paper we introduce a modification of the hypergeometric distribution that caters for the case when the sampling scheme favours the inclusion of units of one of the two types involved, as opposed to the hypergeometric distribution under which all samples are equally likely. The properties of the resulting distribution, termed the generalized hypergeometric, are studied, including the derivation and numerical assessment of a normal approximation of the distribution.
Weak Complexes of Sulfur Compounds with Halide Ligands
Authors: Salama Salama B. , Wasif Saad
Published: May 2017

This review summarizes the study of the formation of SO2 -X- , SOCl2 -X- , SOBr2 -X- , SO2 Cl2 -X-  complexes (X-  = Cl- , Br- , I- , and SCN- ) in pure and mixed solvents of acetonitrile and dimethylsulfoxide over the past 30 years. Spectrometry (290nm-380nm) was the principal technique used for the investigation, since the enthalpies of formation Δ Hfo  of the above complexes are low ( -6.03   -22.51 kJ/mol ). The stability of the complexes depend on the nature of the solvent, acceptor properties of the sulfur compounds, the donor properties of the halide ions and the temperature of the reaction. Also, it was found that the extent of the iodide ion replacement reactions by the other halide depends on the nature of the solvent and the halide ions. SO2 -I-  + X- →  SO2 -X-  + I-  The structures of SO2 -X-  compounds are pyramidal, with X-  at the top of the pyramid, the S atom at the center, and the angle depends on the nature of the halide ion.
Voltage Stability Analysis of Muscat Power System During Summer Weather Conditions
Authors: Ellithy K. , Gastli A. , Al-Alawi S. , Al-Hinai A. , Al-Abri Z.
Published: May 2017

A systematic and general formulation of a Propagation Simulation Program (PSP) is developed for the coherent field of microwave and millimeter wave carrier signals traversing intermediate layered precipitation media taking into account the random behavior of particle size, orientation, shape and concentration distributions.  Based on a rigorous solution of the volumetric multiple-scattering integral equations, the formalism offers the capability of treating the potential transmission impairments on satellite-earth links and radar remote sensing generated by composite atmospheric layers of precipitation in conjunction with the finite polarization isolation of dual-polarized transmitting and receiving antennas. A multi-layered formulation is employed which encompasses an ensemble of discrete particles comprising an arbitrary mixture of ice crystals, melting snow and raindrops that may exist simultaneously along satellite-earth communication paths.
Effect of pH on the Removal of Chromium (Cr) (VI) by Sugar Cane Bagasse
Authors: Ahmed Khan Nasim , Ali Syed Iqbal , Ayub Sohail
Published: May 2017

The industrial estates in India are dominated by small and medium scale industries, which are posing a serious threat to the environment by virtue of discharging effluents of a polluting nature. The problems become severe due to the presence of heavy metals in the effluents. Chromium is widely used in a number of industries such as electroplating, metal finishing, cooling towers, dyes, paints, anodising and leather tanning industries. The toxicity of chromium (VI) is well known and is considered a hazard to the health of humans and animals. The presence of chromium (VI) in aquatic environments at high concentrations is also lethal to marine species. The treatment of chromium bearing effluents have been reported through several methods, such as chemical reduction,  precipitation, ion exchange, electrochemical reduction, evaporation, reverse osmosis and adsorption. However among these, adsorption is found to be highly effective, inexpensive and an easy method to operate. India is an agricultural country and generates a considerable amount of agricultural wastes such as sugar cane bagassess, coconut jute, nut shell, rice straw, rice husk, waste tea leaves, ground nut husk, crop wastes, peanut hulls and fertilizer wastes. Successful studies on these materials could be beneficial to developing countries and could be easily applied as adsorbents for the removal of chromium from wastewater. Most of the previous work highlights the use of commercial activated carbon but these adsorbents are relatively expensive and less feasible to be used in developing countries. Keeping these in view batch experiments have been designed to study the feasibility of sugar cane bagasse to remove chromium (VI) from the aqueous solutions. While evaluationg the impact of various parameters, such as adsorbent does, contact time, initial concentration and pH on chromium removal efficiency, the results indicate a prominent effect of pH on the chromium reduction by the adsorbent used in the present study.
Analysis of Electrical stresses in AC Switches Used for Control of Small Power Motors Present in Household Appliances
Authors: Raingeaud Yves , Galtie Franck , Gonthier Laurent , Baillou Jean
Published: May 2017

This paper describes a study on electric and thermal stresses induced in bidirectional switches used for control of small power motors present in household appliances, in order to find out the possible weakness of the current solution generally made of a triac and to determine the requirements for new dedicated devices in the ASDTM technology. First, a behavioral analysis of these motors must be performed and the interactions between the switch and the load have to be well defined.
Biological Effects of EM Radiations from Mobile Phones
Authors: Ali Adel A. , Al-Naamany Ahmed M.
Published: May 2017

Direct health effects could result following exposure to RF by thermal (heating effects). Recent Studies have shown that there are public fears on effects that can be caused mainly by holding mobile phones close to the body, or as a result of possible non-thermal effects from both phones and base stations.  This paper offers an overview on the biological effects of electromagnetic radiation caused by mobile phones. Exposures of individuals to RF radiation from these sources will depend upon their proximity and may be above those from mobile phone base stations, although still well below guidelines. From a review of the scientific literature, it is concluded that there were no established health effects from exposure to the RF fields from mobile phones. However, there are gaps in knowledge requiring further research, but current knowledge suggests that RF exposure to levels below the guidelines were not a risk to health.
Development and Application of Back-Propagation-Based Artificial Neural Network Models in Solving Engineering
Authors: Al-Alawi Saleh Mohammed
Published: May 2017

Artificial Neural Networks (ANNs) are computer software programs that mimic the human brain's ability to classify patterns or to make forecasts or decisions based on past experience.  The development of this research area can be attributed to two factors, sufficient computer power to begin practical ANN-based research in the late 1970s and the development of back-propagation in 1986 that enabled ANN models to solve everyday business, scientific, and industrial problems.  Since then, significant applications have been implemented in several fields of study, and many useful intelligent applications and systems have been developed.  The objective of this paper is to generate awareness and to encourage applications development using artificial intelligence-based systems.  Therefore, this paper provides basic ANN concepts, outlines steps used for ANN model development, and lists examples of engineering applications based on the use of the back-propagation paradigm conducted in Oman.  The paper is intended to provide guidelines and necessary references and resources for novice individuals interested in conducting research in engineering or other fields of study using back-propagation artificial neural networks.