bluuebunny/crossref_metadata_2025 huggingface dataset:
Cation Distribution in Natural Chromites from Oman
Authors: Al-Alawi Z. , Gismelseed A.M. , Yousif A.A. , Worthing M.A. , Sutherland H.H. , Rais A.M. , El-Zain M.E. , Al-Rawas A.D.
Published: May 2017

Two specimens or natural chromite from the Oman ophiolite were studied using Mossbauer Spectroscopy (MS), X-ray Diffraction (XRD). and Scanning Electron Microscopy (SEM). The diffraction patterns obtained at room temperature showed that the two specimens have a face-centered cubic spinal structure. Their Mossbauer spectra at 295 K. 160 K and 78 K have been fitted to three doublets. assigned to two Fe 2+ at the tetrahedral (A1+,A2) sites and one Fe1+ at the octahedral (B) site. The ferrous-ferric ratio obtained from the Mossbauer analysis together with the atomic concentration derived from the microprobe data are used to derive the chemical formulae for the two specimens. The data also supports also supports  a model of ordered caution distribution in the specimens examined.
Modern Concrete Wall-Units with Improved Thermal Resistance for Housing in Hot Climate
Authors: Pierzchlewicz J.
Published: May 2017

New wall-units have been designed at the Civil Engineering Department of SQU, with improved and reliable thermal insulation properties for construction of buildings in hot climatic conditions. as in the Sultanate of Oman. The thermal resistance of many types of concrete units has been analyzed. Hundreds of various types of the new concrete hollow blocks as well as six-column sections made of these wall-units have been tested in full scale. The relationship of compressive strength of the new concrete hollow blocks, walls made of these units and cube samples has been investigated. The wall columns have been tested under axial load and with various eccentricities. The types of column failure have been studied. The aim of the test was to determine the characteristic compressive strength of the new concrete hollow blocks and the characteristic compressive strength of masonry made of these hollow blocks. The results of the test have shown that the new wall-units could have been used Successfully for construction of the walls in buildings.
Histopathological and Ultrastructural Changes in the Liver and Gills of the Killifish Aphanius Dispar (Cyprinodontidae) Exposed to Aflatoxin B1
Authors: Al-Azri Horiya H. , Ba-Omar Taher , Elshafie Abdulkadir , Barry Michael J
Published: May 2017

Aflatoxin B1 (AFB1) is a mycotoxin which can cause serious toxicity to animals and humans.  The aim of this study was to investigate the effects of AFB1 in Aphanius dispar fish and measure residues in tissues after in vivo exposure. Aphanius dispar were fed diets containing 50, 100, 150 and 200 µg AFB1/kg for 10, 20 and 30 days. At the end of the experiment, the liver and gills were dissected out and processed for light and electron microscopy. During the experiment, no external changes or unusual behavior were observed in the fish. Histopathological and ultrastructural changes in liver appeared under all four treatments: 50, 100, 150 and 200 µg AFB1/kg. Gill tissues were affected at high doses of 100,150 and 200 µg AFB1/kg. Accumulation of AFB1 residues in liver and gill tissues was found to be related to a dose and duration of exposure.
Synthesis and Characterization of Some Macrocylic Complexes Incorporating Indole and 2,2'-Bipyridine or 1,10-Phenanthroline
Authors: Khan Muhammad S. , Al-Rasbi Nawal K. , Constable Edwin C.
Published: May 2017

Complexes of anionic pentadentate macrocyclic ligands by the template condensation of bis(hydrazino)2,2'-bipyridine or 1,10-phenanthroline with an indoledialdehyde have been synthesized. The new Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) macrocyclic complexes have been characterized by analytical and spectroscopic techniques and by conductivity and magnetic susceptibility measurements.
Mobilization and Redistribution of Elements in Laterites of Semail Ophiolite, Oman: A Mass Balance Study
Authors: Al Khirbash Salah , Semhi Khadija
Published: May 2017

Several samples of laterites were collected from four paleosol profiles, Ibra, East Ibra, Al-Russayl, and Tiwi representing the vertical lithological variation within each profile. The mineralogical and geochemical composition of laterites in every section revealed differences in thickness and redistribution of elements reflecting different conditions of weathering processes. Elemental mass balance was calculated for every profile relative to the parent rock. The results indicated redistribution of elements from the surface to deeper zones with an enrichment of elements in the saprolite and oxide zones. Among the different sections, the profile of East Ibra composite 1 and 2 is characterized by high concentration of all elements compared to the other profiles. Sc/Fe ratio in different zones indicates low values for the profile of Tiwi profile 1, Ibra profile and Al-Russayl composite 2 and 3 profile due to the significant enrichment of Fe in these zones independently of redox conditions. Large fluctuations characterize Th/U ratios and reflect redox condition more reduced in Tiwi area than in East Ibra and Al-Russayl areas.
Investigation of the Direction of Spontaneous Magnetisation at 0 K in HoCo2 and TmFe2
Authors: Carboni Carlo , Al-Abri Eman
Published: May 2017

The direction of spontaneous magnetisation at 0 K across a phase orientation boundary in rare-earth laves phase compounds is computed as a function of the ratio of magnetic to electrostatic interactions. The phase boundary and range of parameters used for the computation correspond to the portion of the orientational phase diagram where experimental data can be obtained. In the series of pseudo-binary compounds (Gdx Ho1-x )Co2 and (Yx Ho1-x )Co2 the range of parameters covers the continuous transition from the <100> to the <110> orientations. The nmr measurements on this series show that the direction of spontaneous magnetisation is at intermediate orientation between the <100> and <110> directions. The material TmFe2, which is in the vicinity of a discontinuous orientational boundary, is also discussed.
Rolling Optimization Method for Humanoid Robots
Authors: Zaier Riadh
Published: May 2017

In this paper, a method of optimizing the rolling amplitude needed for a stable and smooth walking movement of a humanoid robot is considered. The optimization algorithm was based on minimizing a cost function defined by the rolling overshoot. The amplitude of the rolling during locomotion was calculated using the lateral zero moment point (ZMP) position. The initial value of the rolling was the static rolling that corresponds to the position of the ZMP at the center of the support polygon. The algorithm consisted of performing a ZMP calculation at two points that correspond to single support phases. Simplifying the robot as an inverted pendulum, the gyro feedback controller parameters were tuned to have a passive-like walking motion and a faster response of the robot state to the equilibrium point at single support phase. Experimental results, using HOAP-3 of Fujitsu, showed that the algorithm was successfully implemented along with the locomotion controller. With the optimal rolling technique, the humanoid robot could exhibit a stable and smooth walking movement.
Geological Assessment of the Khor Kharfot Sediments, Western Dhofar Region, Sultanate of Oman
Authors: Abbasi Iftikhar A.
Published: May 2017

Khor Kharfot is part of a coastal estuarine wetland system located in the western part of the Dhofar Governorate preserving a pristine ecosystem supporting a distinct vegetation and animal habitat. A sand barrier along the khor (local term for wetlands) mouth controls the mixing of fresh and marine water in the enclosed lagoon. In order to understand the geological controls on the khor formation, a geological map of the khor barrier and inlet area is prepared. The khor is bounded by Cretaceous and Tertiary carbonate rock sequences which are cut by a number of faults. The khor mouth and barrier are comprised of late Holocene deposits divided into seven units including i) beach sand, ii) beach sand mixed with wadi gravels, iii) scree and coastal dunes, iv) lagoon, v) soil and boulders, vi) wadi gravels, and vii) talus. The khor developed as an open estuary which changed to a barrier dominated lagoon due to falling fresh water supplies as a consequence of dwindling Khareef rains. The lagoon water is brackish due to the mixing of fresh and marine water and supports a distinct flora and fauna.
Two Dimensional Short Time Hartley Transforms
Authors: Sundararajan Narasimman , Ebrahimi A. , Vasudha Nannappa
Published: May 2017

The Hartley transform, as in the case of the Fourier transform, is not suitably applicable to non-stationary representations of signals whose statistical properties change as a function of time. Hence, different versions of 2-D short time Hartley transforms (STHT) are given in comparison with the short time Fourier transform (STFT). Although the two different versions of STHT defined here with their inverses are equally applicable, one of them is mathematically incorrect/incompatible due to the incorrect definition of the 2-D Hartley transform in literature. These definitions of STHTs can easily be extended to multi-dimensions. Computations of the STFT and the two versions of STHTs are illustrated based on 32 channels (traces) of synthetic seismic data consisting of 256 samples in each trace. Salient features of STHTs are incorporated.
Reduction of Linear Functional Systems using Fuhrmann's Equivalence
Authors: Boudellioua Mohamed S.
Published: May 2017

Functional systems arise in the treatment of systems of partial differential equations, delay-differential equations, multidimensional equations, etc. The problem of reducing a linear functional system to a system containing fewer equations and unknowns was first studied by Serre. Finding an equivalent presentation of a linear functional system containing fewer equations and fewer unknowns can generally simplify both the study of the structural properties of the linear functional system and of different numerical analysis issues, and it can sometimes help in solving the linear functional system. In this paper, Fuhrmann's equivalence is used to present a constructive result on the reduction of under-determined linear functional systems to a single equation involving a single unknown. This equivalence transformation has been studied by a number of authors and has been shown to play an important role in the theory of linear functional systems.
An Improved Mnemonic Device for Thermodynamic Relations
Authors: Kim Younghun , Selvaraj Rengaraj
Published: May 2017

An improved mnemonic device for thermodynamic relations between state variables and potentials was proposed in the form of a thermodynamic circle. Based on separating the Born square into an inner square (T, P, V, and S) and an outer circle (G, A, U, and H), relations such as Legendre transforms, Maxwell equations, equations to compute variables, and differential equations for thermodynamic variables can be recalled easily. The thermodynamic circle has a cross-arrow at its center and can be used to intuitively determine the sign of all thermodynamic relations.
Combined Effects of Hall Current and Heat Transfer on Peristaltic Transport of a Nanofluid in a Vertical Tapered Channel Through a Porous Medium
Authors: Abdellateef Ahmed I. , Ul Haque Syed Z.
Published: May 2017

The influences of Hall currents and heat transfer on peristaltic transport of a nanofluid in a vertical porous tapered channel through a porous medium are investigated theoretically and graphically under the assumptions of low Reynolds number and long wavelength and the flow investigated is in a wavy frame of reference. Analytical solutions are obtained for temperature, axial velocity, stream function and pressure gradient. Graphical results are sketched for various embedded parameters.
Global Dynamics and Sensitivity Analysis of a Vector-Host-Reservoir Model
Authors: ELmojtaba Ibrahim M. , Biswas Santanu , Chattopadhyay Joydev
Published: May 2017

The role of animal reservoir in the disease dynamics is not yet properly studied. In the present investigation a mathematical model of a vector-host-reservoir is proposed and analyzed to observe the global dynamics of the disease. We observe that the disease free equilibrium is globally asymptotically stable if the basic reproduction number ( ) is less than unity whereas unique positive equilibrium is globally asymptotically stable if and transcritical bifurcation occurs at . Our numerical result suggests that the biting rate plays an important role for the propagation of the disease and the recovery rate has not such important contribution towards eradication of the disease. We also perform sensitivity analysis of the model parameters and the results suggest that the death rate of reservoir may be used as a control parameter to eradicate the disease.
Computational Study of Geometry, Solvation Free Energy, Dipole Moment, Polarizability, Hyperpolarizability and Molecular Properties of 2-Methylimidazole
Authors: Firoz Khan Mohammad , Rashid Ridwan Bin , Islam Shahidul M. , Rashid Mohammad A.
Published: May 2017

Ab initio calculations were carried out to study the geometry, solvation free energy, dipole moment, molecular electrostatic potential (MESP), Mulliken and Natural charge distribution, polarizability, hyperpolarizability, Natural Bond Orbital (NBO) energetic and different molecular properties like global reactivity descriptors (chemical hardness, softness, chemical potential, electronegativity, electrophilicity index) of 2-methylimidazole. B3LYP/6-31G(d,p) level of theory was used to optimize the structure both in the gas phase and in solution. The solvation free energy, dipole moment and molecular properties were calculated by applying the Solvation Model on Density (SMD) in four solvent systems, namely water, dimethylsulfoxide (DMSO), n-octanol and chloroform. The computed bond distances, bond angles and dihedral angles of 2-methylimidazole agreed reasonably well with the experimental data except for C(2)-N(1), C(4)-C(5) and N(1)-H(7) bond lengths and N(1)-C(5)-C(4) bond angle. The solvation free energy, dipole moment, polarizability, first order hyperpolarizability, chemical potential, electronegativity and electrophilicity index of 2-methylimidazole increased on going from non-polar to polar solvents. Chemical hardness also increased with increasing polarity of the solvent and the opposite relation was found in the case of softness. These results provide better understanding of the stability and reactivity of 2-methylimidazole in different solvent systems.
Fourth-Order Approximation of the Fundamental Matrix of Linear System of Differential Equations
Authors: Hussein A.M.
Published: May 2017

A fourth-order approximation to the fundamental matrix of a system of linear differential equations is presented in closed form as a matrix exponential. The matrix exponential is then discretized over the interval of integration l‘adc approximation together with the method of scaling and squaning (Moler et at 1978) is used to evaluate the matrix exponential. This approach is suitable for solving both initial and boundary value problems with mixed boundary conditions. The approximating matrix can also be used as an integrating operator for methods which require information about the solution along the discretized subintervals. An example of a boundary value problem with mixed boundary condition is presented.
Mycoflora and Mycotoxigenic Moulds of Pistachio Nuts for Human Consumption in the Sultanate of Oman
Authors: Elshafie A. E. , AL-Shally N. S.
Published: May 2017

Mycoflora of 75 cans of different batches and brands of pistachio nuts purchased in the Sultanate of Oman was studied. A number of fungi were isolated, with percentages of contaminated nuts [average between brands ] as follows: Aspergillus niger 14.8%, Penicillium spp. 13.6%, A flavus 9.7%, A nidulans 1.6%, and < l % for Cladosporium cladosporoides, Alternaria alternata , A ochraceeus and Ulocadium consortiale. Significant differences were found among the batches and brands contaminated by A flavus. A flatoxin B, was found only in one sample out of 1.5 assayed at a level of 2 ug/kg.
Quantitative Analysis of Clay Minerals Using X-Ray Diffraction Technique. Part 1
Authors: Al-Rawas Amer , Sutherland Hector , Hago A.W. , Basma Adnan , Al-Shihi Badar
Published: May 2017

Qualitative and quantitative analysis of clay minerals are important in the evaluation of the swelling potential of expansive soils A relatively simple method for the quantification of clay minerals of Al-Khod (Northern Oman) using an X-ray diffraction method is described in detail in this paper. The method is based on the additions of known internal standards to the clay sample. The clay investigated in this study contained montmorillonite, palygorskite, illtte and kaolinite. Internal standards of these minerals were mixed with the clay at different proportions and intensities of reflected peak areas were measured. It was found that the peak areas intensities relate linearly with additions of different proportions of standards. From these intensities, the clay minerals present in the clay of Al-khod were estimated.
Computer-Aided Design for Estimating Foundation Uplift on Expansion Soils
Authors: A. Basma Adnan , Al-Rawas Amer Ali
Published: May 2017

This work presents a methodology to determine in-situ heave of foundations due to soil expansion. A total of 206 soil specimens from a semi-arid region (lrbid city in northern Jordan) were tested in the laboratory to produce a model for predicting the swell percent, SP. The results indicate that SP is strongly dependent on the placement conditions (initial water content and dry unit weight), clay content of the soil and the initial applied pressure. Utilizing this model, an Advanced BASIC computer program was written to evaluate in-situ heave. It was verified using actual field data: The program provides a Simple means for approximately determining foundation heave.
BMOA Characterization with Families of Cauchy Transforms
Authors: Abu Muhanna Yusuf , Yallaoui El-Bachir
Published: May 2017

In this paper we prove a number of results on Cauchy transforms of generalized type given by Borel measures supported on the class of analytic functions mapping the unit disc into the unit desk.
A New record of Hydroptila cruciata Ulmer in southern Oman with notes on its Larval Biology
Authors: Victor R.
Published: May 2017

Fourth and fifth instar larvae of a hydroptilid richoptcran, Hydroprtila Ulmer 1912 were collected in the Sultanate of Oman for the first time. The fifth instar larva constructs a purse-case With filamentous algae. Notes on the habitat characteristics and the larval biology of this species are given.
Ultrastructural Changes in the Epithelium of the Stomach of Aphanius dispar (Cyprinodontidae), Due to Stress from Starvation
Authors: Ba-Omar Taher A. , Victor Reginald
Published: May 2017

Ultrastructural changes in the epithelium of the stomach  of Aphanius dispar, a cyprinodont fish, due to starvation have been described.  The changes in the epithelium after 24, 48, 72, 96, and 120 hours have been discussed.  The  degeneration of the epithelial cells commenced after 24 hours and steadily progressed till 96 hours at which the maximum change was observed. Changes in response to starvation include the disappearance of lipid droplets, mitochondrial damage, goblet cells degeneration, morphological aberration of the nuclei  and overall abnormalities  in the structural integrity of the rugae.  This study confirms that stress due to starvation causes significant pathomorphological changes in the stomach in four days.
Surface Plasmons for Probing Optical Data of Multi- Layered Thin Films
Authors: Rais A. , Sellai A.
Published: May 2017

In this paper, we show how optical excitation of surface plasmons (SPs) can be used to obtain optical and geometrical parameters of specific layers in multi-layered thin film systems. The optimum coupling phenomenon between incoming p-polarized light and SPs appears as a minimum in the reflectance that is calculated using a standard matrix formalism. The sensitive dependence of the reflectance minimum on optical and geometrical parameters suggests that they can be determined accurately by fitting the measured attenuated total reflectance (ATR) to the matrix-calculated reflectance using the Simplex minimization method. The procedure is applied to the multi-layered system: Prism / Air gap / Al-oxide / Al / GaAs. At fixed incident light wavelength, the fitting parameters are the Al-oxide optical constant and the thickness of the air gap, Al-oxide and Al layers. Fortran codes are implemented for the reflectance calculations and the fitting procedures. The results show that the theoretical reflectance fits well the measured ATR at 633 nm wavelength. Moreover, the modeled Al-oxide optical constant at this wavelength agrees well with the literature. However, the reflectance fits are less good at 590 nm and 458 nm wavelengths and their modeled Al-oxide optical constants show a dispersion effect in disagreement with the literature. The modeled geometrical parameters are consistent with the nominal values.
Homochiral Acyl Isocyanates as Diagnostic NMR Probes for the Enantiomeric Purity of Chiral Alcohols
Authors: Roos Gregory H. P. , Donovanb Anthony R.
Published: May 2017

The first reported acyl and sulfonylisocyanates were developed and tested in reactions with chiral alcohols to afford diastereomeric carbamates. NMR analysis of these investigates the chemical shift discrimination that would allow these activated isocyanates to be used as diagnostic probes of enantiomeric purity.
Intelligent Systems for Active Program Diagnosis
Authors: Ramadhan Haider Ali , Shihab Khalil
Published: May 2017

Intelligent program diagnosis systems are computer programs capable of analyzing logical and design-level errors and misconceptions in programs. Upon discovering the errors, these systems provide intelligent feedback and thus guide the users in the problem-solving process. Intelligent program diagnosis systems are classified by their primary means of program analysis. The most distinct split is between those systems that are unable to analyze partial code segments as they are provided by the user and must wait until the entire solution code is completed before attempting any diagnosis, and those that are capable of analyzing partial solutions and providing proper guidance whenever an error or misconception is encountered. This paper gives an overview of the field and then critically compares work accomplished on several closely related active diagnosis systems, emphasizing such issues as the representation techniques used to capture the domain knowledge required for the diagnosis, ability to handle the diagnosis of partial code segments of the solutions, features of the user interfaces, and methodologies used in conducting the diagnosis process. Finally the paper presents a detailed discussion on issues related to active program diagnosis along with various design considerations to improve the engineering of this approach to intelligent diagnosis. The discussion presented in this paper tackles the issues referred above within the context of DISCOVER, an intelligent system for programming by discovery.
Photovoltaic Cells and Systems: Current State and Future Trends
Authors: Bourdoucen Hadj , Jervase Joseph A. , Al-Badi Abdullah , Gastli Adel , Malik Arif
Published: May 2017

Photovoltaics is the process of converting solar energy into electrical energy. Any photovoltaic system invariably consists of solar cell arrays and electric power conditioners. Photovoltaic systems are reliable, quiet, safe and both environmentally benign and self-sustaining. In addition, they are cost-effective for applications in remote areas. This paper presents a review of solar system components and integration, manufacturing, applications, and basic research related to photovoltaics. Photovoltaic applications in Oman are also presented. Finally, the existing and the future trends in technologies and materials used for the fabrication of solar cells are summarized.
Converged Networking: A Review of Concepts and Technologies
Authors: Ahmed Ali Adel , Al-Naamany Ahmed M.
Published: May 2017

Converged networking is an emerging technology thrust that integrates voice, video, and data traffic on a single network. Converged networking encompasses several aspects, all of which are related to the aggregation of networking activity. Such aspects include, Payload convergence, Protocol convergence, Physical convergence, Device convergence, Application convergence, Technology convergence, etc. In recent years the Internet has developed into a global data network that is highly accepted as a multimedia information platform, which has the potential to develop into an alternative carrier network in the future. Several convergence scenarios have been recently proposed, ranging from integrating communication services and computer application into two separate networks, to building a seamless multimedia network, which converges the Central Office based network and the Internet in a single network, thereby enabling telecommunications operators and service provider's tremendous investment in existing network infrastructure to be fully utilized. This paper offers introduction and review of the networking technologies. The paper presents the existing multiple networks into two infrastructures: an ATM/Frame Relay (Ethernet)- based corporate network with integrated voice, video, and data traffic and an Internet-based network for secure intranet, extranet and remote access. This work is aimed at summarizing the internetworking basics and technologies which are essential for the emerging converged networking systems. The specific areas addressed here are networking basics, networking technologies, types of traffic, and convergence of computer and communication networks.
Electromagnetic Modeling of the Propagation Characteristics of Satellite Communications Through Composite Precipitation Layers, Part II: Results of Computer Simulations
Authors: Al-Rizzo H.M. , Al-Hafid H.T. , Tranquilla J.M.
Published: May 2017

A versatile Propagation Simulation Program (PSP) is developed to assess the degrading effects caused by the concurrent occurrences of an arbitrary mixture of ice plates and needles, melting snow and raindrops which may impede the reliability of dual-polarized satellite communications systems carrying independent channels on a single radio path. Specifically, results are presented for the Cross Polarization Discrimination (XPD) due to ice and rain, differential attenuation, Da, and differential phase shift, Df, due to rain and average specific attenuation, a, and phase shift, f , due to the melting layer at hitherto unconsidered frequencies. The inclusion of an ice-cloud medium is found to possess significant effects on rain-induced XPD even for low ice concentrations, particularly at low fade levels. The relative contribution of the melting layer on rain-induced attenuation is extensively studied for frequencies from 1 to 100 GHz and rain rates below 20 mm/h.
Flow Past A Rotating Circular Cylinder and A Rotlet Using the Finite-Difference Method
Authors: El Bashir T. B. A.
Published: May 2017

In this paper the flow generated by a rotlet in the presence of a circular cylinder is considered. We introduce a transformation which simplifies the equations and boundary conditions. We use the finite-difference method to obtain results in excellent agreement with all the available analytical results. Results are presented for Reynolds numbers, based on the diameter of the cylinder, in the range 0 ≤ Re ≤ 20 and the rotational parameter, α , in the range 0 ≤α ≤ 3 and strength of rotlet, β , in the range 0 ≤ β ≤ 3 . The results are found to be applicable over a wide range of values of α and β . The calculated values of the drag, lift and moment coefficients and the general nature of the streamline patterns are in good agreement with analytical results . The method is then utilized to obtain new results for which no analytical solution is possible.
Plasma Analysis in Normal Green Sea Turtles, Chelonia mydas, During two Different Periods of Nesting at Ras Al- Hadd, Sultanate of Oman
Authors: AlKindi Abdulaziz.Y.A. , Mahmoud Ibrahim.Y. , Khan Humaid
Published: May 2017

Plasma composition which includes total protein, cholesterol, lactate, glucose, uric acid, urea, CO2, and electrolytes (Ca++, K+, Na+, Mg++, PO4-3, Cl-), and plasma osmolarity were analyzed in normal adult nesting green turtles Chelonia mydas. Blood samples were collected in June-October at the peak of the nesting season and in November-May during the non-peak period. Plasma electrolytes values, except for PO4-3 and Cl- were significant between the two periods. Values for total proteins and uric acid were significantly different during the two periods but urea values were insignificant. Osmolarity was unchanged during the two periods. During nesting the sea turtles undergo strenuous and exhaustive exercise and like other lung breathing reptiles, they ventilate intermittently, thus, they rely on anaerobic metabolism during the nesting exercise. Plasma concentrations of lactate and CO2 were significant but glucose values remained stable and unchanged during the two nesting periods. Higher concentrations of total protein during June compared to October may be related to the type and the availability of diet in the waters near the nesting sites. High concentrations of electrolytes and lactate are perhaps related to more stressful conditions during June because of higher crowding and intense competition for nesting sites. The aim of this study was to analyze the role of these parameters during nesting activity to evaluate changes under two different crowding conditions and gather information for future population health assessments.
Determination of Sugar and Mineral Contents in some Omani Fruits
Authors: Z.Al-Kindy Salma M , Abdulnour Abdulrahman O , Al-Rasbi Maryam M.
Published: May 2017

Omani fruits were analyzed for their reducing sugar, total sugar contents and some minerals. Among the minerals studied were Ca, Mg, Na, K and P. The amounts of total sugar and reducing sugar were within the range of values reported in the literature for the analysis of fruits conducted elsewhere. The amounts of the minerals differ from the reported literature values. This may be attributed to soil composition, climate and type of cultivar.
A finite Volume Runge-Kutta Ellam Method for the Solution of Advection Diffusion Equations
Authors: Al-Lawatia Mohammed , Sharpley Robert C. , Wang Hong
Published: May 2017

We develop a finite volume characteristic method for the solution of the advection-diffusion equations which model the contaminant transport through porous medium. This method uses a second order Runge-Kutta approximation for the characteristics within the framework of the Eulerian Lagrangian localized adjoint methods (ELLAM). The derived scheme conserves mass, symmetrizes the governing equations and generates accurate numerical solutions even if large time steps are used.  Numerical experiments comparing several competitive methods using a standard test example are presented to illustrate the performance of the method.
A Modified Asynchronous Transfer Mode Fuzzy Policer
Authors: Rizk M.R.M. , Rashwan H. , Abdel Aziz A.
Published: May 2017

A Modified Fuzzy policer for Asynchronous Transfer Mode is introduced. In a preceding fuzzy policer model the time window (time interval where ATM cells are accepted in the policer) is not synchronized with the source activity. In the proposed one, the time windows are not consecutive but are triggered by the first arriving cell. The modified policer gives good improvement to the selectivity, and minimizes the congestion over the path. This improvement can be significant for multiple channels.
Joint Symbol and Frame Synchronization for Direct- Detection Optical Communication Systems
Authors: Bastaki Eesa M. , Tan Harry H.
Published: May 2017

The problem of joint symbol and frame synchronization in direct-detection optical PPM communication systems under the assumption of known slot timing is considered here. The optimum maximum-likelihood (ML) and sub-optimum rules for this joint symbol and frame synchronization problem are derived. The reason of Georghiades's (1985) incorrect ML rule is discussed in this paper.
Comparative Study of Load Frequency Controller Designs for Interconnected Power Systems
Authors: Albadi M. , Awladthani A. , Alomeiri B. , Ellithy K.
Published: May 2017

This paper presents a comparative study of three different load frequency (LF) controller designs for interconnected power systems. They are the conventional integral controller, a controller based on the pole-placement technique, and a controller based on optimal control law. Each controller has been designed to improve the dynamic response of system frequency and tie line power flow under a sudden load change. The results obtained using a MATALB computer program show the effectiveness of the LF controller designs. The results also show that the combined optimal controller with conventional integral controller can provide good damping to the system and reduce the overshoot.
Derivatized Pentadentate Macrocyclic Ligands and Their Transition Metal Complexes
Authors: Khan Muhammad S. , Al-Rasbi Nawal K. , Constable Edwin C. , Dale Adrian R. , Lewis Jack
Published: May 2017

The reaction of the pendant hydroxyethyl group in the planar pentadentate macrocyclic ligand,1,11-bis(2’-hydroxyethyl)-4,8;12,16;17,21-trinitrilo-1,2,10,11-tetraazacyclohenicosa- 2,4,6,9,12,14,18,20-octaene (L2), derived from the condensation of 2,6-pyridinedialdehyde with 6,6’-bis(2’ hydroxyethylhydrazino) -2,2’-bipyridine (L1), has been investigated. Esterification reactions are facile, and the reaction of the hydroxyethyl-substituted macrocycle with thionyl chloride yields a chloroethyl derivative. Metal complexes of the new derivatized macrocyclic ligands L3-6having general formula ML3-6X2.nH2O (M = Mn, Fe, Co, Ni, Cu, Zn) are readily prepared.
Effect of the Fineness of Artificial Pozzolana (Sarooj) on the Properties of Lime-Pozzolana Mixes
Authors: Hago Abdel Wahid , Al-Rawas Amer Ali , Al-Sidairi Awadh
Published: May 2017

Strength development of lime-pozzolana mortars is affected by the fineness of the pozzolan. This paper examines the effect of the fineness of artificial pozzolana on the strength development of lime-pozzolana mixtures. An artificial pozzolana produced by calcining clays from Oman was used in this study. The artificial pozzolana is locally known as “Sarooj”, and is currently being used in a big project for the restoration of historical monuments undertaken by the Omani Ministry of National Heritage and Culture. The artificial pozzolana was ground to various degrees of fineness, blended with hydrated lime with a ratio of 3:1, and the resulting mortar was used to make hardened mortar cubes. Strength of mortar cubes was measured at ages of 7, 14, 28 and 90 days of casting. The experimental results show that good artificial pozzolanas show a linear correlation between the Blaine fineness of the artificial pozzolana and the compressive strength, but such relationship does not exists for weak type pozzolanas. The fineness of the artificial pozzolana has its most significant effect on delayed strength gain, with more pronounced effect for good type pozzolan.
Mineralogy of the Tertiary Clay Deposits in Makkah and Rabigh Quadrangles, West Central Arabian Shield, Saudi Arabia
Authors: Basyoni M.H. , El Askary M.A. , Saad N.A. , Taj R.J.
Published: May 2017

The mineralogy of the Tertiary clay deposits in Makkah and Rabigh quadrangles was thoroughly investigated by X-ray diffraction and differential thermal and thermogravimetric analyses in addition to other techniques. Results show that the investigated samples are predominantly composed of montmorillonite (Ca++ and/or Mg++ rich variety) and kaolinite, associated with subordinate illite and minor chlorite. Mixed layer montmorillonite-illite is recorded only in two samples. The relative abundance of these minerals by X-ray diffraction analysis showed that the studied clay deposits are of three types. The first, which is the most common, is highly montmorillonitic, the second is made up of a mixture of montmorillonite followed by kaolinite and illite and the third is highly kaolinitic with some montmorillonite. Generally, kaolinite shows a southward increase in Makkah quadrangle while chlorite, as a minor component, shows a northward increase in Rabigh quadrangle.
Efficient Synthesis of the Plant Growth Regulator Ancymidol
Authors: Patzelt Heiko
Published: May 2017

The important cytochrome P450 inhibitor ancymidol is used as a plant growth retardant and has potential for various medicinal applications. However its high price sets economic limits to large-scale applications. Here a short and high-yielding synthesis is reported, providing ancymidol in substantial amounts in a cost- and time-efficient way.
A Monte Carlo Method for Low Pressure Radio Frequency Discharges
Authors: Settaouti Lahouaria , Settaouti Abderrahmane
Published: May 2017

There is increasing interest in glow discharges because of their importance to a large number of application fields, like the microelectronics industry, flat plasma display panel technology, the laser and light industry and analytical spectrochemistry. To improve the capabilities of rf glow discharges, a good understanding of the discharge physics is highly desirable. The typical calculated results include the radio frequency (rf) voltage, the electrical field distribution, the density of argon ions and electrons, the electron energy distribution function and information about the collision processes of the electrons with the Monte Carlo model. These results are presented throughout the discharge axis and as a function of time in the rf cycle. Moreover, we have investigated how many rf cycles have to be followed before a periodic steady state is reached.
Synchronization and Oscillator Death in Diffusively coupled lattice oscillators
Authors: Wasike Adu A.M.
Published: May 2017

We consider the synchronization and cessation of oscillation of a positive even number of planar oscillators that are coupled to their nearest neighbours on one, two, and three dimensional integer lattices via a linear and symmetric diffusion-like path. Each oscillator has a unique periodic solution that is attracting. We show that for certain coupling strength there are both symmetric and antisymmetric synchronization that corresponds to symmetric and antisymmetric non-constant periodic solutions respectively. Symmetric synchronization persists for all coupling strengths while the antisymmetric case exists for only weak coupling strength and disappears to the origin after a certain coupling strength.
Solvent Extraction of Thorium(IV) by Didodecylphoric Acid
Authors: Khalili Fawwaz I. , Mousa Khaled M. , Soudani Ehsan I.
Published: May 2017

Solvent extraction of Thorium (VI) ion from perchlorate solution using didodecylphosphoric acid, DDPA, in chloroform diluent was studied. The effects of stripping hydrochloric acid concentration, stripping time, extraction time, DDPA concentration, pH, ionic strength, supporting electrolyte and temperature on the extraction processes have been studied. From the distribution coefficient values at different temperatures,the enthalpy, the free energy and the entropy changes associated with the extraction processes were determined. The composition of the complex formed was established to be Th(ClO4)4-nRn(HR)5-n where, n=1 or 2 and (HR)2 represents the dimer of DDPA.
Step-Wise Group Screening Designs with Unequal A-Priori Probabilities and Errors in Observations
Authors: Manene M.M.
Published: May 2017

The performance of step-wise group screening with unequal a-priori probabilities in terms of the expected number of runs and the expected maximum number of incorrect decisions is considered. A method of obtaining optimal step-wise designs with unequal a-priori probabilities is presented for the case in which the direction of each defective factor is assumed to be known a -priori and observations are subject to error. An appropriate cost function is introduced and the value of the group size which minimizes the expected total cost is obtained.
Solution of a Nonlinear Functional Equation
Authors: Covachev Valery C. , Yurtsever H. Ali
Published: May 2017

In the present paper a generalization of a theorem of I.B. Risteski (2004) concerning the solution of a nonlinear functional equation is given. The proof is based on a parametric approach by introducing a parameter in an arbitrary set , and on a matrix method for solving linear functional equations.
Vector Directional Distance Rational Hybrid Filters for Color Image Restoration
Authors: Khriji L.
Published: May 2017

A new class of nonlinear filters, called vector-directional distance rational hybrid filters (VDDRHF) for multispectral image processing, is introduced and applied to color image-filtering problems. These filters are based on rational functions (RF). The VDDRHF filter is a two-stage filter, which exploits the features of the vector directional distance filter (VDDF), the center weighted vector directional distance filter (CWVDDF) and those of the rational operator. The filter output is a result of vector rational function (VRF) operating on the output of three sub-functions. Two vector directional distance (VDDF) filters and one center weighted vector directional distance filter (CWVDDF) are proposed to be used in the first stage due to their desirable properties, such as, noise attenuation, chromaticity retention, and edges and details preservation. Experimental results show that the new VDDRHF outperforms a number of widely known nonlinear filters for multi-spectral image processing such as the vector median filter (VMF), the generalized vector directional filters (GVDF) and distance directional filters (DDF) with respect to all criteria used.
Development of Asphalt Pavement Temperature Models for Oman
Authors: Hassan H.F. , Al-Nuaimi A.S. , Taha R. , Jafar T.M.A.
Published: May 2017

Asphalt pavements form an integral part of any transportation system. The structural capacity of the hot mix asphalt concrete layers depends on many factors including its temperature. Moreover, temperature can be a major contributor to several types of distresses. Therefore, temperature is a significant factor that affects the performance and life span of a pavement. The Sultanate of Oman's road network expanded at a phenomenal pace from approximately 10 km of paved roads in 1970 to 9,673 km in 2001. with the recent SHRP and LTTP research findings, it was necessary to investigate the applicability of the models developed from these research studies to Oman's environmental conditions and more generally to the Arabian Gulf climate. This paper presents the research undertaken to develop models to predict high and low asphalt pavement temperatures in Oman. A pavement monitoring station was set-up at the Sultan Qaboos University (SQU) campus to monitor air, pavement temperatures and solar radiation. Data were collected for 445 days. Daily minimum and maximum temperatures were recorded. A regression analysis was used to develop the low pavement temperature model. A stepwise regression was used to develop high temperature models using air temperature, solar radiation, and duration of solar radiation as independent variables. The developed models were compared with the SHRP and LTPP models. The SHRP and LTPP models were found to be more conservative than the developed models, which are more suitable for predicting pavement temperatures in Oman, and more generally in the Gulf region.
2D Idealisation of Hollow Reinforced Concrete Beams Subjected to Combined Torsion, Bending and Shear
Authors: Al-Nuaimi A.S. , Bhatt P.
Published: May 2017

This paper presents a finite element model for idealisation of reinforced concrete hollow beams using 2D plane elements. The method of ensuring compatibility between the plates using two-dimensional model to analyze this type of structures is discussed. Cross-sectional distortion was minimised by incorporating end diaphragms in the FE model. Experimental results from eight reinforced concrete hollow beams are compared with the non-linear predictions produced by a 2D in-house FE program. The beam dimensions were 300x300 mm cross section with 200x200 mm hollow core and 3800 mm long. The beam ends were filled with concrete to form solid end diaphragms to prevent local distortion. The beams were subjected to combined bending, torsion and shear. It was found that the two-dimensional idealisation of hollow beams is adequate provided that compatibility of displacements between adjoining plates along the line of intersection is maintained and the cross-sectional distortion is reduced to minimum. The results from the 2D in-house finite element program showed a good agreement with experimental results.
A Multi-Step Approach for Scheduling Tasks with Synchronization on Clusters of Computers
Authors: Arafeh B.R.
Published: May 2017

In this work, a two-step approach is adopted for scheduling tasks with synchronous inter-task communication. To that end, an efficient algorithm, called GLB-Synch, is introduced for mapping clusters and ordering tasks on processors. The algorithm used the information obtained during the clustering step for selecting a cluster to be mapped on the least loaded processor. A performance study has been conducted on the GLB-Synch algorithm by simulation. A multi-step scheduling setup has been performed based on a previously developed algorithm for clustering DAGs with synchronous communication, called NLC-SynchCom, and using synthesized DAGs. We have shown by analysis and experimentation that the GLB-Synch algorithm retains the same low complexity cost of the first step for clustering. The performance results highlight the drawback of synchronization on speedup scalability.
Inexpensive and Accurate Measuring Device forWater Constitute in Oil
Authors: Habli M. , Meribout M. , Al-Naamany A. , Al Busaidi K.
Published: May 2017

This paper presents an inexpensive and accurate measuring device for water constitute in oil. The new device is based on the relationship between the water constitute in oil and the pressure of a sample from the oil. Experimental results show that the device can attain a very high resolution that can reach up +/- 0.4% and it can be used to measure a full range of water percentage levels (0-100%). Experimental results showed good agreement with theory.
Direct Design of T-Beams for Combined Load of Bending and Torsion
Authors: Alnuaimi A. S. , Al-Jabri K.S. , Hago A.W.
Published: May 2017

Tests were conducted on five reinforced concrete T-beams subjected to combined load of bending and torsion. Elastic stress field in conjunction with Nielsen's 2D yield criterion for reinforced concrete subjected to in-plane forces were used in the Direct Design Method for the design of reinforcement. The beam dimensions were: flange width = 600mm, flange thickness = 150mm, web width = 200mm, total depth = 600mm and beam length = 5.2m. Required reinforcement calculated using the Direct Design Method was compared with the ACI and BSI codes. It was found that the Direct Design Method requires longitudinal reinforcement similar to the ACI code but less than the BSI code. In the transverse direction, the Direct Design Method requires much less reinforcement than both codes. The main variable studied was the ratio of the maximum twisting moment to the bending moment which was varied between 0.6 and 1.5. Good agreement was found between the design and experimental failure loads. Most of the longitudinal and transverse steel yielded or reached near yield stress when the design load was approached. All beams failed near the design loads and undergone ductile behaviour until failure. The results indicate that the Direct Design Method can be successfully used to design reinforced concrete T-beams for the combined effect of bending and torsion loads.