bluuebunny/crossref_metadata_2025 huggingface dataset:
Chiral Polyhedra Derived from Coxeter Diagrams and Quaternions
Authors: Koca Mehmet , Koca Nazife Ozdes , Al-Shueili Muna
Published: May 2017

There are two chiral Archimedean polyhedra, the snub cube and snub dodecahedron together with their dual Catalan solids, pentagonal icositetrahedron and pentagonal hexacontahedron. In this paper we construct the chiral polyhedra and their dual solids in a systematic way. We use the proper rotational subgroups of the Coxeter groups and to derive the orbits representing the solids of interest. They lead to the polyhedra tetrahedron, icosahedron, snub cube, and snub dodecahedron respectively. We prove that the tetrahedron and icosahedron can be transformed to their mirror images by the proper rotational octahedral group so they are not classified in the class of chiral polyhedra. It is noted that vertices of the snub cube and snub dodecahedron can be derived from the vectors, which are linear combinations of the simple roots, by the actions of the proper rotation groupsand  respectively. Their duals are constructed as the unions of three orbits of the groups of concern. We also construct the polyhedra, quasiregular in general, by combining chiral polyhedra with their mirror images. As a by-product we obtain the pyritohedral group as the subgroup the Coxeter group and discuss the constructions of pyritohedrons. We employ a method which describes the Coxeter groups and their orbits in terms of quaternions.
Numerical Experience with Damped Quasi-Newton Optimization Methods when the Objective Function is Quadratic
Authors: Al-Baali Mehiddin , Purnama Anton
Published: May 2017

A class of damped quasi-Newton methods for nonlinear optimization has recently been proposed by extending the damped-technique of Powell for the BFGS method to the Broyden family of quasi-Newton methods. It has been shown that this damped class has the global and superlinear convergence property that a restricted class of 'undamped' methods has for convex objective functions in unconstrained optimization. To test this result, we applied several members of the Broyden family and their corresponding damped methods to a simple quadratic function and observed several useful features of the damped-technique. These observations and other numerical experiences are described in this paper. The important role of the damped-technique is shown not only for enforcing the above convergence property, but also for improving the performance of efficient, inefficient and divergent undamped methods substantially (significantly in the latter case). Thus, some appropriate ways for employing the damped-technique are suggested.
Global Search Strategies for Solving Multilinear Least-Squares Problems
Authors: Andersson Mats , Burdakov Oleg , Knutsson Hans , Zikrin Spartak
Published: May 2017

The multilinear least-squares (MLLS) problem is an extension of the linear least-squares problem. The difference is that a multilinear operator is used in place of a matrix-vector product. The MLLS is typically a large-scale problem characterized by a large number of local minimizers. It originates, for instance, from the design of filter networks. We present a global search strategy that allows for moving from one local minimizer to a better one. The efficiency of this strategy is illustrated by the results of numerical experiments performed for some problems related to the design of filter networks.
The Squared Slacks Transformation in Nonlinear Programming
Authors: Armand Paul , Orban Dominique
Published: May 2017

In this short paper, we recall the use of squared slacks used to transform inequality constraints into equalities and several reasons why their introduction may be harmful in many algorithmic frameworks routinely used in nonlinear programming. Numerical examples performed with the sequential quadratic programming method illustrate those reasons. Our results are reproducible with state-of-the-art implementations of the methods concerned and mostly serve a pedagogical purpose, which we believe will be useful not only to practitioners and students, but also to researchers.
Model Calibration in Option Pricing
Authors: Loerx Andre , Sachs Ekkehard W.
Published: May 2017

We consider calibration problems for models of pricing derivatives which occur in mathematical finance. We discuss various approaches such as using stochastic differential equations or partial differential equations for the modeling process. We discuss the development in the past literature and give an outlook into modern approaches of modelling. Furthermore, we address important numerical issues in the valuation of options and likewise the calibration of these models. This leads to interesting problems in optimization, where, e.g., the use of adjoint equations or the choice of the parametrization for the model parameters play an important role.
Superstatistics in Random Matrix Theory
Authors: Abul-Magd A.Y.
Published: May 2017

Random matrix theory (RMT) provides a successful model for quantum systems, whose classical counterpart has chaotic dynamics. It is based on two assumptions: (1) matrix-element independence, and (2) base invariance. The last decade witnessed several attempts to extend RMT to describe quantum systems with mixed regular-chaotic dynamics. Most of the proposed generalizations keep the first assumption and violate the second. Recently, several authors have presented other versions of the theory that keep base invariance at the expense of allowing correlations between matrix elements. This is achieved by starting from non-extensive entropies rather than the standard Shannon entropy, or by following the basic prescription of the recently suggested concept of superstatistics. The latter concept was introduced as a generalization of equilibrium thermodynamics to describe non-equilibrium systems by allowing the temperature to fluctuate. We here review the superstatistical generalizations of RMT and illustrate their value by calculating the nearest-neighbor-spacing distributions and comparing the results of calculation with experiments on billiards modeling systems in transition from order to chaos.
The Induction of Electric Currents in a Conducting Spherical Cap with Geomagnetic Applications: A Semi-analytical Approach for the Axisymmetric Case
Authors: Ashour A.A. , Abou-Dina M.S. , Ghaleb A.F.
Published: May 2017

The objective is to introduce a semi-analytical method for solving axisymmetric problems of electromagnetic induction in thin spherical caps placed in a time-varying magnetic field due to an axial magnetic dipole or in a time-varying uniform axial magnetic field. This method provides approximate solutions to mathematically difficult mixed boundary-value problems governing the induction of electric currents in thin sheets, for arbitrary angles of the cap. Numerical results are given and discussed. The best approximations were obtained for sheets with integrated conductivity decreasing to zero towards the edge of the sheet. The case of uniform conductivity, characterized by weak singularities of the induced magnetic vector potential at the rim of the cap, yielded relatively large errors and is dealt with separately within an improved model. The method may be adequately extended to deal with other problems involving more complicated geometries, arbitrary electric conductivity distributions and inducing magnetic fields, in two or three dimensions, for various geophysical applications.
Optimised Methods for Quantitative Analysis of Solasodine and its Glycoside Solamargine by High Performance Liquid Chromatography
Authors: Al-Sinani Sana S. , Eltayeb Elsadig A.
Published: May 2017

Improved and simplified HPLC conditions for the determination and quantification of both the steroidal glycoalkaloid (solamargine) and its aglycone (solasodine) are described. The best isocratic conditions were developed using a C18 column and methanol in combination with an ammonium dihydrogen phosphate buffer. The isocratic conditions were shown to be more reproducible, less time consuming and to give sharper peaks (better separation). The effects of adjusting solvent: buffer ratio, buffer pH and buffer molarity were evaluated.
Effects of Pesticide Temephos on the Liver of Aphanius dispar (Rüppell 1828) (Pisces: Cyprinodontidae): A Microscopic Study
Authors: Ba-Omar Taher A. , Al-Kharusi Iman , Victor Reginald
Published: May 2017

The effects of  the pesticide temephos, at different concentrations, on the liver of Aphanius dispar, (Rüppell 1828) a cyprinodont fish, have been described. The changes in the liver tissue after exposure to 1 ppm, 5 ppm, 10 ppm and 25 ppm concentrations of temephos have been presented. Light and transmission electron microscopy showed that the degeneration of the liver cells commenced after exposure to 1 ppm and steadily progressed to show maximum changes at 25 ppm. Histopathological changes included the dilation of sinusoids, an increase in the number of lipid droplets and cytoplasmic vacuolation, pyknosis of the nuclei and focal necrosis. These results falsify the claim that temephos is a non-systemic poison.
Synthesis of Doped and non-Doped Nano MgO Ceramic Membranes
Authors: Labib Shiraz
Published: May 2017

Doped and non-doped MgO coated thin films on alumina substrates were prepared using a chelating sol-gel method under controlled conditions to prepare nanomaterials with unprecedented properties. The effect of doping of ZnO on thermal, surface and structural properties was investigated using DTA-TG, BET and XRD respectively. Also microstructural studies and coating thickness measurements of MgO thin film were conducted using SEM. An increase in the thermal stability of MgO with increasing ZnO doping percent was observed. The increase of ZnO doping percent showed a marked decrease in the average particle size of MgO powder as a result of the replacement of some Mg2+ by Zn2+ which has similar ionic radius as Mg2+. This decrease in particle size of MgO was also related to the decrease of the degree of MgO crystalinity. The increase of ZnO doping also showed a marked decrease in coating thickness values of the prepared membranes. This decrease was related to the  mechanism of ZnO doping into a MgO crystal lattice.
Neorotalia omanensis and Operculina musawaensis from the Sultanate of Oman
Authors: Al-Sayigh Abdul Razak Siddiq
Published: May 2017

Two new species of larger benthic foraminifera, Neorotalia omanensis n. sp. and Operculina musawaensis n. sp. are described and illustrated from the eastern Oman Mountains. N. omanensis n. sp. occurs in the Musawa Formation in association with the planktonic foraminifera Morozovella edgari and Truncarotaloides topilensis indicating an early to middle Eocene age (P10-P13). Operculina musawaensis n. sp. occurs in the Abat Formation in association with the planktonic foraminifera Acarinina esnaensis and A. soldadensis indicating an early Eocene age (P6).  This is the first known record showing the presence of genus Neorotalia in the Middle East. Representatives of the larger foraminiferal genus Linderina sp. are also described and illustrated from the Musawa Formation and compared with the published Linderina species in the surrounding countries.
Homotopy Perturbation Method For Fractional Shallow Water Equations
Authors: Al-Khaled Kamel , Al-Safeen M. K.
Published: May 2017

In this paper, the homotopy perturbation method is adopted to find explicit and numerical solutions for systems of non-linear fractional shallow water equations. The fractional derivatives are described in the Caputo sense. We apply both the homotopy perturbation method and the homotopy analysis method, to solve  certain shallow water equations with time-fractional derivatives, and explicitly construct convergent power series solutions. The  results obtained reveal that these  methods are  both very effective and simple for finding approximate solutions. Some numerical examples and plots are presented to illustrate the efficiency and reliability of these methods.
Velocity Profiles for Flow of Omani Crude Oils and Other Liquids
Authors: Arafin Sayyadul , Mujibur Rahman S. M.
Published: May 2017

Velocity profiles of Newtonian immiscible liquids undergoing laminar flow between two horizontal plates under pressure gradient are investigated using a momentum balance equation. The differential equation describing the flow has been solved and equations for the velocity profiles of a two-layer and three-layer liquid systems are presented. As examples, we show flow patterns of two-layer water-crude oil system and three-layer system involving water, tetrachloromethane, xylene, cyclopentane and hexane. A distinctive pattern is noticeable between the velocity profiles of heavy (API 19.19) and light (API 40.89) Omani crude oils.
The Effect of Salinity on Solamargine and Solasonine Contents of Solanum incanum Plants Grown in Oman
Authors: Al Sinani Sana S. , Eltayeb Elsadig A.
Published: May 2017

In addition to its traditional medicinal importance, Solanum incanum (thorn apple) is also a rich source of important cytotoxic glycoalkaloids such as solamargine and solasonine. The effect of salinity stress on solamargine and solasonine production by Solanum incanum plants grown in soil has been investigated. Salinity stress has been applied by adding NaCl to the soil, in concentrations: 0.0 (control), 75, 150, and 225 mM for 8 weeks. HPTLC method was used for analysis of solamargine and solasonine in leaves, stem and roots. A positive correlation was observed between 150 mM NaCl salinity and production of solamargine and solasonine in leaves. In roots, solamargine content was not affected by NaCl treatment, whereas solasonine content increased with a short-term salinity treatment. However, salinity seems to reduce the production of solamargine and solasonine in the roots of Solanum incanum. The possibility of using NaCl as an efficient and economical elicitor of glycoalkaloid production in Solanum incanum plants is rejected on the basis of the results obtained.
Recognition of Minerals Using Multispectral Remote Sensing Data: A Case Study in the Sultanate of Oman
Authors: Rajendran Sankaran , Nasir Sobhi
Published: May 2017

The present study demonstrates the capability of a multispectral sensor for the detection of the minerals in the rocks surrounding the Rusayl and Al Jafnayn regions, Sultanate of Oman. The study of spectral absorptions of rocks and minerals in the visible and near infrared (VNIR) and short wavelength infrared (SWIR) spectral bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) using the Spectral Angle Mapper (SAM) supervised image classification technique has provided information on the occurrence of minerals in the rock types of the regions. The study shows the occurrence of carbonate minerals in the limestone formations and of poorly altered silicate minerals in the basic dyke rocks of the study regions. The analysis of minerals over the ancient terraces and recent alluvial deposits show that the deposit materials are derived from the dykes and foliated gabbro source rocks. The image interpretation is compared to the geological map, verified in the field and confirmed through laboratory analyses. The satellite data and the image processing techniques used have potential in the recognition of minerals in the rocks of the study region and could be used in similar arid regions elsewhere in the world.
A Test for Dominance
Authors: Dorvlo Atsu S.S.
Published: May 2017

In some selection situations a simple majority is not enough to indicate that one item dominates the others. In this paper we develop a simple procedure for testing the dominance of one item with respect to others in a multi option situation. Expressions are given for computing the relevant p-values. The procedure is illustrated.
The Stratigraphy and Structure of the Madamar-Salakh-Qusaybah Range and Natif-Fahud Area in the Oman Mountains
Authors: Hanna S.S. , Smewing J.D.
Published: May 2017

Melanges and debris flows with clasts derived from the top of the Natih Formation found in shales in the base of the Aruma Group indicate that a period of Structural growth on the platform took place during Aruma deposition in the Late Cretaceous. In this respect the platform in the Jebel Salakh area may have undergone a similar period of structural growth in the Late Cretaceous to the Fahud area where a syn-Aruma normal fault down throwing to the South accounts for a difference in the stratigraphic thickness of the Aruma of 1 km. A younger series of debris flows in the Aruma of the Sufrat al Khays area to the South of Jehel Salakh is dated as Campanian/Maastrichtian. The clasts in these flows were derived exclusively from the Simsima limestones. Natih-derived elasts are conspicuously absent. This is taken to indicate that the Madamar-Salakh Qusaybah range was covered by Aruma sediments at this time and did not form the distinctive positive feature seen at present - i.e. Madamar-Salakh-Qusaybah range folding though partly Late Cretaceous is mainly Post-Manslrichtian in age. This Post Maastrichtian event in the Madamar-Salakh-Qusaybah range produced a series of doubly-plunging anticlines in the Cretaceous strata- These folds show a high degree of brittle extension in the form of normal faults and extensional fractures, The faults are delineated by fault gouge with visibly interconnected void space. In the subsurface, if such fractures were developed in a fold closure similar to those seen at the surface in the Madamar-Salakh-Qusaybah range. then they could provide preferred conduits for oil flow and the harrier to fluid flow provided by the Aruma shale seal could lead to a hydrocarbon accumulation.
Effect of Compositional Grading On reservoir Performance
Authors: Al-Rumhy M. , Al-Bemani A. , Boukadi F.
Published: May 2017

In reservoirs with thickness exceeding fifty meters, compositional guiding has been found to cause significant variation in performance. Main fluid properties, governing the magnitude of reservoir performance, such as density; formation volume factor and fluid viscosity experience variation due to varying fluid composition along the hydrocarbon column. These variations cause erroneous estimation of stock-tank oil in place and may infer reservoir engineers to consider inappropriate secondary oil recovery methods, for example. In the presence of gravity segregation within the oil column, heavy ends will form a heavy oil blanket in the lower part of the reservoir. Such a scenario may result in poor displacement and an earlier breakthrough when water drive is the dominant fluid flow mechanism. In this paper reservoir performance due to varying reservoir fluid composition has been examined using  reservoir simulation analysis and recommendations for better characterization of reservoir fluid sampling are outlined.
Magnetism in Iron-Zirconium Systems
Authors: Elzain M.E. , Al-Yousif A.D. , Gismelseed A.M.
Published: May 2017

The discrete variational method is used to solve the Khon-Sham equation in the spin-polarized local density approximation for Fe-Zr and Fe-Zr-H clusters, representing iron-zirconium and hydrogenated iron-zirconium alloys. The local  magnetic moment and hyperfine field at the Fe site were found to decrease, whereas the contact charge density and occupation number were found to increase with Zr contents. The Zr site in clusters with high Fe contents acquires a negative magnetic moment. When H is trapped at an interstitial site next-neighboring an Fe atom, the magnetic moment and hyperfine field are enhanced, while the contact charge density is reduced. ‘The opposite occurs when H occupies a neighboring interstitial site to Fe. For Zr atoms the local magnetic moment is found to become less negative with H at the neighboring position. We conclude from this calculation that H is trapped in Fe-Zr systems at positions which are nearest to Zr and next-nearest to Fe atoms.
A Unique Common Coupled Fixed Point Theorem for Four Maps in Partial b-Metric-Like Spaces
Authors: Khan Mohammad S. , Rao Konduru P.R. , Parvathi Kandipalli V.S.
Published: May 2017

We prove the existence of a unique common coupled fixed point theorem for four mappings satisfying a general contractive condition on partial b-metric-like spaces. We also give an example to illustrate our main theorem. Our theorem generalizes and improves the theorem of [1].
Spin Torque Oscillator for High Performance Magnetic Memory
Authors: Sbiaa Rachid , Bouziane Khaled
Published: May 2017

A study on spin transfer torque switching in a magnetic tunnel junction with perpendicular magnetic anisotropy is presented. The switching current can be strongly reduced under a spin torque oscillator (STO), and its use in addition to the conventional transport in magnetic tunnel junctions (MTJ) should be considered. The reduction of the switching current from the parallel state to the antiparallel state is greater than in  the opposite direction, thus minimizing the asymmetry of the resistance versus current in the hysteresis loop. This reduction of both switching current and asymmetry under a spin torque oscillator occurs only during the writing process and does not affect the thermal stability of the free layer.
Energy Management through Heat Integration: a Simple Algorithmic Approach for Introducing Pinch Analysis
Authors: Al-Azri Nasser A.
Published: May 2017

Pinch analysis is a methodology used for minimizing energy and material consumption in engineering processes. It features the identification of the pinch point and minimum external resources. Two common established approaches are used to identify these features: the graphical approach and the algebraic method, which are time-consuming and susceptible to human and calculation errors when used for a large number of process streams. This paper presents an algorithmic procedure to heat integration based on the algebraic approach. The algorithmic procedure is explained in a didactical manner to introduce pinch analysis for students and novice researchers in the field. Matlab code is presented, which is also intended for developing a Matlab toolbox for process integration.
Numerical Wave Solutions for Nonlinear Coupled Equations using Sinc-Collocation Method
Authors: Al-Khaled Kamel
Published: May 2017

In this paper, numerical solutions for nonlinear coupled Korteweg-de Vries(abbreviated as KdV) equations are calculated by the Sinc-collocation method. This approach is based on a global collocation method using Sinc basis functions. The first step is to discretize time derivative of the KdV equations by a classic finite difference formula, while the space derivatives are approximated by a weighted scheme. Sinc functions are used to solve these two equations. Soliton solutions are constructed to show the nature of the solution. The numerical results are shown to demonstrate the efficiency of the newly proposed method.
Thermal and Transport Properties of Mafic and Ultramafic Rocks of Oman Ophiolite
Authors: Arafin Sayyadul , Singh Ram N.
Published: May 2017

Thermal and other physical properties of rocks and minerals are of considerable significance for deriving mineralogical and compositional models of the Earth's mantle. We have determined these properties for the mafic rock such as gabbro and ultramafic rock like harzburgite of the Oman ophiolite suite by utilizing the Debye characteristic property ,Θ-
4D Pyritohedral Symmetry
Authors: Koca Nazife O. , Al Qanobi Amal J.H. , Koca Mehmet
Published: May 2017

We describe an extension of the pyritohedral symmetry in 3D to 4-dimensional Euclidean space and construct the group elements of the 4D pyritohedral group of order 576 in terms of quaternions. It turns out that it is a maximal subgroup of both the rank-4 Coxeter groups W (F4) and W (H4), implying that it is a group relevant to the crystallographic as well as quasicrystallographic structures in 4-dimensions. We derive the vertices of the 24 pseudoicosahedra, 24 tetrahedra and the 96 triangular pyramids forming the facets of the pseudo snub 24-cell. It turns out that the relevant lattice is the root lattice of W (D4). The vertices of the dual polytope of the pseudo snub 24-cell consists of the union of three sets: 24-cell, another 24-cell and a new pseudo snub 24-cell. We also derive a new representation for the symmetry group of the pseudo snub 24-cell and the corresponding vertices of the polytopes.
Model-Tracing Based Approach to Intelligent Program Diagnosis
Authors: Ramadhan Haider Ali
Published: May 2017

Model-tracing based approach to intelligent program diagnosis and tutoring emphasizes the fact that the student’s design decisions are traced as the students develops the program Systems based on this model monitor the user's actions as the moves along the solution path, automatically  analyzes partial solutions for semantic errors and misconceptions, and offers guidance whenever he deviates from  the correct solution path. In this way, the system always checks to see if the student is following a design path of an idea model. Buggy paths are pruned as soon as they are discovered. Through this approach to automatic diagnosis and tutoring a model-tracing system can (1) diagnose very specific errors and misconceptions, and provide clear advice and explanation within proper and immediate context (2) simplify the engineering of automatic diagnosis by preventing multiple bugs and errors. However, this approach is very directive and interventionist. The users highly constrained in the solutions that can be developed, since he must conforms to the task decomposition and coding sequence enforced by model-tracing systems. This paper critically looks at model-tracing and suggests several solutions and guidelines for bypassing the  shortcomings associated with the approach.
Calibration of Transit Operations Planning (TOP) Model and Evaluation of Bus Transit Route Performance in Riyadh
Authors: Koushki P.A. , Ali G.A. , Al-Nuaim Y.A.
Published: May 2017

Public transit systems provide mobility for a large percentage of urban residents very cost-effectively and with minimum negative impact on the environment. ln spite of their vital and indispensable services; however , The majority of transit systems worldwide suffer from financial neglect and are forced to rely heavily on government subsidies for survival. In response to the rapidly shrinking funds and subsidy levels transit managements have to focus attention on ways to improve service operations. The management of public transit systems in Saudi Arabia is no exception to this trend. This study is aimed at evaluating the service performance of a sample of regular (fixed-route, fixed schedule) bus transit routes in Riyadh, Saudi Arabia. Utilizing a microcomputer-based program, the bus transit service operational measures of fare, headway, vehicle size and routing were analyzed. To account for the socio-economic and cultural differences of transit ridership in Riyadh, time/cost elasticities of demand as well as walk time and bus travel time parameters of the model were calibrated. Evaluation of the impact of changes in service operational measures suggested that no change in operational variables could improve the very low productivity of one of the sample study routes. A cost-reduction strategy which includes the use of smaller vehicles and less-frequent service runs should improve the low productivity of this route. Findings also indicated that a small increase in fare would pay for the total operation and maintenance costs of the other routes. The authors, however, do not recommend an increase in fare for a variety of reasons; the low income level of the captive riderships, the enormous financial resources of the country , and the multi-dimentional role of transit systems in providing urban mobility with minimum negative impacts on the  environment.
Recurrence Relations for the Equilibrium Means of Distributions Arising in Chemical Reactions
Authors: Elsheikh E.K.
Published: May 2017

In this paper we derive recurrence relations that describe how the equilibrium mean of the number molecules of a reactant varies with each of the parameters defining the initial state for four basic reversible chemical reactions. In essence, the relations provide a rationale for updating the equilibrium mean following the addition (or removal) of a molecule of one of the types involved in the reaction, there being a relation for each type. With a new parameterization introduced for each reaction, the relations provide a convenient means of evaluating the means, variances and other important moments without any need to work out the underlying distributions. As an application, the relations are used to numerically assess-approximate expressions for the means and variances.
Effect of Wind Environment on the response of Buildings in Oman
Authors: Qamaruddin Mohammed , Al-Oraimi Salem K.
Published: May 2017

An investigation has been carried out to study the effect of the wind parameters on the response of multistory buildings subjected to wind induced forces. This study is concerned with the wind response of the buildings located at six building sites in Sohar, Thumrait and Saiq regions of Oman. A typical plan of multistory-framed building has been chosen for the present investigation. The Wind and the other related data appropriate to these regions have been used in the analysis. It turns out from the present study that the response of the building located at a Site in a country terrain of a region has higher values than the response obtained for the same building if constructed in a town terrain of the same region With other parameter combinations remaining invariant. It is recommended that a database for the wind parameters, based on the available wind and other related data for different regions of Oman, should be developed for the design of buildings subjected to wind induced farces.
Constant Information Design for Binary Response Data
Authors: Abdelbasit K.A.
Published: May 2017

A major problem is designing experiments when the assumed model is nonlinear, is the dependence of the designs on the values of the unknown parameters we consider in this article designs for binary data and generalize the constant information criterion suggested by Fisher (1922). The criterion calls for designs that achieve a specific proportion of the total constant information. This leads to designs where dependence of Fisher’s information on the unknown parameters is very little, thus leading to constant variances. We show that such designs exist for any single parameter model, extending Fisher‘s result for the exponential model. We discuss the construction of such designs and investigate their performance as measured by the achievement of constant information. When two parameters are needed to specify the model , we show that experiments can be designed so that the determinant of the information matrix is independent of the parameters. Construction of designs and examining their performance are also investigated for the two parameter case.
Determination of Ascorbic Acid in Oman Citrus Fruits
Authors: Al-Kindi KS.M.Z. , Abdelnour A.O. , Al-Siyabi Rahma S.
Published: May 2017

Omani citrus fruits were analyzed for their Vitamin C (ascorbic and AA) content by a titration method involving  N-bromosuccinimide (NBS) as an oxidizing  agent and by high performance liquid  chromatography. Vitamin C content was also determined after storage at different temperatures. Vitamin C contents of the fruits were found to lie within  the values reported in the literature.
Spermatogenesis and Spermiogenesis of the Aphanius Dispar
Authors: Ba-Omar Taher A.
Published: May 2017

Light and transmission electron microscopy were used to study the structure of various stages of germ cells of the Aphanius dispar (Ruppell l828) in Oman. A dispar testes were of cystic type. Different stages of spermatogonia, spermatocytes and spermatids were observed within the cysts. Each cyst is occupied by a group of germ cells almost all in the same stage. The morphology and ultra structure of the nuclei and cytoplasmic organelles of the germ cells are described. Some flagella possessing lateral side fins and some biflagellated spermatozoa were seen.
Solvent Extraction of Uranium (VI) by Didodecylphosphoric Acid
Authors: Mousa Khaled , Khalili Fawwaz
Published: May 2017

Solvent extraction of uranium(Vl) ion from perchlorate solution using didodecylphosphorie acid, DDPA, in toluene diluent was studied. The effects of stripping nitric 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 UO2(CLO4)(HR2)(HR)2 where, (HR)2 represents the dimer of DDPA.
Applying Halstead's Metric to Oberon Language
Authors: Masoud Fawaz Ahmed
Published: May 2017

Oberon is a small, simple and difficult programming language. The guiding principle of Oberon was a quote from Albert Einstein: "Make it as simple as possible, but not simpler". Oberon language is based on few fundamental concepts that are easy to understand and use. It supports two programming paradigms: the procedural paradigm, and the object-oriented paradigm This paper provides the application of Halstead's software science theory to Oberon programs. Applying Halstead's metric to the Oberon language has provided the analysis and measurements for module and within module maintenance complexity of programs written in Oberon. This type of analysis provides a manager or programmer with enough information about the maintenance complexity of the Oberon programs. So they can be aware of how much effort they need to maintain a certain Oberon program. The maintenance complexity of the programs written in Oberon or any other language is based on counting the number of operators and operands within the statements of the tested program. The counting process is accomplished by a program written in C language- Results are obtained, analyzed, and discussed in detail.
Experimental Investigation and Failure Analysis of Fastened GRP under Bending Using Finite Element Method and Artificial Neural Networks
Authors: Abdennour C. Seibi , Al-Alawi M.
Published: May 2017

This paper presents a novel approach that predicts the strength and failure modes of jointed Glass Reinforced Polyester (GRP) samples under bending using Finite Element Method (FEM) and Artificial Neural Network (ANN). The mechanical behavior of fastened glass fiber reinforced plastics composites under bending have been experimentally investigated. Samples were obtained from Amiantit Oman, a manufacturing company operating in Russail Industrial Zone in the Sultanate of Oman. The experimental program involved the conduct of three point bending tests as well as bending tests of mechanically fastened joints under static loads. The experimental results showed that the dimensions of the specimen such as the bending span length, specimen width, and specimen pitch affect GRP strength and stiffness. FEM and ANN results predicted accurately the types of failure modes and their locations along the specimens and compared well with the experimental results.
On the Excitation of Instability Waves in Plane Poisuille Flow by a Concentrated Source at the Wall
Authors: Al-Maaitah Ayman
Published: May 2017

The paper addresses the excitation of instability waves in plane Poiseuille flow by means of a concentrated source at the wall. The aim of this paper is to investigate the relation between the source amplitude and the excited wave amplitude for  various flow and source parameters .The source is modeled by a time harmonic Dnae function and the generated disturbance is investigated By applying Founrier transform on the resulting linearized Navier-Stokes equation in the streamwise direction, the problem is resolved using inverse Fourier transform and the residue theorem. The theoretical formulation explains some observations by previous experiments on similar cases of excitation. Moreover, the calculations demonstrate that the disturbance amplitude increases as the excitation frequency decreases for a fixed Reynolds number, while, on the other hand, it  increases as Reynolds number decreases for a fixed frequency.
Endocrine, Physiological and Histopathological Responses of Fish and their Larvae to Stress with Emphasis on Exposure to Crude Oil and Various Petroleum Hydrocarbons
Authors: AL-Kindi A. Y. A. , Brown J.A. , Waring C.P.
Published: May 2017

Various endocrine and physiological responses of fish exposed to forceful physical and chemical stimuli are reviewed with emphasis on the effects of crude oils and their hydrocarbon constituents. The chemistry and toxicity of petroleum hydrocarbons are examined and methods for experimental exposure of fish to crude oil and petroleum hydrocarbons are considered. A variety of blood-borne parameters recognized as reliable tools in determining the relative severity of stress in fish are reviewed. The effects of stress and petroleum hydrocarbons on endocrine responses including changes in plasma catecholamines, corticosteroids, and thyroid hormones are reviewed. The physiological responses: changes in plasma glucose, osmotic and ionic regulation, blood oxygen, hematocrit and hemoglobin concentration are explored, and histopathological effects of crude oil on fish are reviewed. Recent studies of the effects of petroleum hydrocarbons on fish larvae are considered and the increased sensitivity of the early life stages of fish are highlighted.
State-of-the-Art-Review of Collapsible Soils
Authors: AL-Rawas A. A.
Published: May 2017

Collapsible soils are encountered in arid and semi-arid regions. Such soils cause potential construction problems due to their collapse upon wetting. The collapse phenomenon is primarily related to the open structure of the soil. Several soil collapse classifications based on parameters such as moisture content, dry density, Atterberg limits and clay content have been proposed in the literature as indicators of the soil collapse potential. Direct measurement of the magnitude of collapse, using laboratory and/or field tests, is essential once a soil showed indications of collapse potential. Treatment methods such as soil replacement, compaction control and chemical stabilization showed significant reduction in the settlement of collapsible soils. The design of foundations on collapsible soils depends on the depth of the soil, magnitude of collapse and economics of the design. Strip foundations are commonly used when collapsing soil extends to a shallow depth while piles and drilled piers are recommended in cases where the soil extends to several meters. This paper provides a comprehensive review of collapsible soils. These include the different types of collapsible soils, mechanisms of collapse, identification and classification methods, laboratory and field testing, treatment methods and guidelines for foundation design.
Geological and Engineering Classification Systems of Mudrocks
Authors: Al-Rawas Amer , Cheema Tariq , Al-Aghbari Mohammed
Published: May 2017

Mudrocks are a diverse group of very fine-grained argillaceous sedimentary rocks that are frequently encountered in most types of engineering projects. Upon excavation, the release of overburden stress and changes in the moisture content may cause certain apparently well indurated mudrocks to slake, producing a soil-like material. Because many mudrocks are nondurable, they have gained a reputation as problematic soft rocks. Geologists and engineers are confronted with the problem of selecting adequate parameters for accurately evaluating engineering behavior of mudrocks. The use of a single parameter (e.g. grain-size) is never considered to be enough and a combination of several parameters are normally preferred for the classification of mudrocks. Compressive strength, slake durability index, plasticity characteristics, swelling potential, absorption and density are some of the parameters that had been used by several investigators in the past. In order to overcome this problem, considerable research attention has recently been devoted to the use of geological properties (grain size, clay content and clay composition, texture, fracture frequency, degree of lamination, etc.) in conjunction with the engineering characteristics for classification purposes. This paper describes the origin and occurrence of mudrocks, and their different types of classification tests and systems.
State-of-the-Art Methods for Electric Power Systems Voltage Stability Analysis
Authors: Al-Khusaibi T.M. , Ellithy K. A. , Irving M.R.
Published: May 2017

This paper presents a literature survey on the subject of voltage stability analysis of power systems. The survey describes several published methods and techniques used to determine voltage stability indices. These indices predict proximity to voltage instability and collapse problems. The Q-V and P-V curves; singular value decomposition; modal analysis; test function; reduced determinant; loading margin by multiple power flow solutions; local load margins; thevenin/load impedance; and energy function are the methods which have been decribed in the paper. The methods described are based on the original work that first proposed them. They are based on the power-flow system model, where the variation of real and reactive powers are assumed to be the main parameters driving the system to voltage instability. Some of the described methods were applied on the IEEE 30-bus power system.
Electromagnetic Modeling of the Propagation Characteristics of Satellite Communications Through Composite Precipitation Layers, Part1: Mathematical Formulation
Authors: Al-Rizzo H.M. , Al-Hafid H.T. , Tranquilla J.M.
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.
Research Trends : Natural Products as Pest, Microbial Disease an Tumour Control Agents
Authors: Fatope M.O. , Al-Kindi Salma M. Z. , Abdulnour Abdulrahman O.
Published: May 2017

The zeal to conquer human, agronomic, and veterinary diseases or pests has always sustained research interests directed at finding new medications from under explored biodiversity. The adoption of bioassay methods, which correlate with prevention, inhibition and reversal of diseases or elimination of pests, in screening natural products for bioactive compounds is critical to the discovery of new medications. This article focuses on areas of natural products chemistry that connect academia with industry. It discusses the technical skills needed to find bioactive compounds from microbes, marine invertebrates, plants and insects, highlighting the mode of action of selected bioactive compounds and bioassay models for detecting them. It also reviews methods and prospects of genetic manipulation of organisms to produce unnatural natural products of therapeutic importance.
Variation in Seedling Characteristics of Five Populations of Acacia tortilis From the United Arab Emirates in Response to Increasing Sodium Chloride Concentrations
Authors: Al-Ansari Fatma. M. , Modawi Rashied. S.
Published: May 2017

Seeds of Acacia tortilis collected from 5 sites around the city of Al Ain in the United Arab Emirates were germinated in 4 concentrations of sodium chloride (0, 20, 90 and 150 mM of NaCl). Percent of germination, rate of germination, seedling moisture content, root and shoot lengths and seedling lengths were all significantly affected by salt stress. Seeds collected from the different sites were significantly different in their response to salinity conditions. Variations in the response of seedlings from different sites to the different salt treatments suggest an underlying genetic variability within the A. tortilis   populations, possibly resulting from variations in the prevailing local conditions. Urbanization in the area and the changing water table may have divided A. tortilis into distinct subpopulations that are significantly different in seedling characteristics and their response to saline conditions.
Desert Nitrogen Cycles: Fecal Nitrogen From a Population of the Sahelian Tree Locust in Oman
Authors: Robinson Michael D.
Published: May 2017

This research quantifies the amount of nitrogen deposited by the tree locust, Anacridium melanorhodon, during an irregular population outbreak in an Acacia tortilis woodland in Oman. The average standing crop of feces was 65.28g m-2. The mean fecal crude protein and nitrogen were respectively, 20.14 and 3.22 g/100 gash-free dry weight. A hectare of this woodland would contain approximately 1.1 kg of fecal nitrogen beneath the trees. This single contribution by the locusts equals about one-third of the total standing crop of detrital nitrogen under perennial vegetation in a hectare of the Mohave Desert of North America. This, and the fact that grasshoppers are diverse and seasonally abundant in deserts, suggests they may be important organisms in nitrogen cycles.
Influence of Aging Conditions on Fatigue Fracture Behaviour of 6063 Aluminum Alloy
Authors: Siddiqui Rafiq Ahmed , Al- Araimi Saeed Ali , Turgutlu Ahmet
Published: May 2017

Aluminum - Magnesium - Silicon (Al-Mg-Si) 6063 alloy was heat-treated using under aged, peak aged and overage temperatures. The numbers of cycles required to cause the fatigue fracture, at constant stress, was considered as criteria for the fatigue resistance. Moreover, the fractured surface of the alloy at different aging conditions was evaluated by optical microscopy and the Scanning Electron Microscopy (SEM). The SEM micrographs confirmed the cleavage surfaces with well-defined fatigue striations. It has been observed that the various aging time and temperature of the 6063 Al-alloy, produces different modes of fractures. The most suitable age hardening time and temperature was found to be between 4 to 5 hours and to occur at 460 K. The increase in fatigue fracture property of the alloy due to aging could be attributed to a vacancy assisted diffusion mechanism or due to pinning of dislocations movement by the precipitates produced during aging. However, the decrease in the fatigue resistance, for the over aged alloys, might be due to the coalescence of precipitates into larger grains.
Selection of Liner Materials and Design of Hazardous Water Facilities in Saudi Arabia
Authors: Abduljauwad Sahel N. , Dakkak Ali M.
Published: May 2017

Rapid development in Saudi Arabia has produced a broad spectrum of wastes.  In the last two decades, several refineries and petrochemical industries have been established. These industries have produced sludges and other toxic wastes which need proper planning for their handling and disposal. This paper covers design and selection of liner materials for two hazardous waste disposal sites. One of them is located in the Eastern Province of Saudi Arabia, while the second one is located in the Western part. The paper will present complete design details of the natural compacted and geosynthetic soil liners and the leachate collection and removal system for primary liners and leak detection/leachate collection and removal system for secondary liners.