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Articles 191641 - 191670 of 5154021

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Stability Of The Synchronization Manifold In An All-To-All Time Lag- Diffusively Coupled Oscillators, Adu A.M. Wasike Apr 2025

Stability Of The Synchronization Manifold In An All-To-All Time Lag- Diffusively Coupled Oscillators, Adu A.M. Wasike

Sultan Qaboos University Journal For Science

we consider a lattice system of identical oscillators that are all coupled to one another with a diffusive coupling that has a time lag. We use the natural splitting of the system into synchronized manifold and transversal manifold to estimate the value of the time lag for which the stability of the system follows from that without a time lag. Each oscillator has a unique periodic solution that is attracting.

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Anisotropy In Rfe2 Intermetallics: An Nmr Study, C Carboni Apr 2025

Anisotropy In Rfe2 Intermetallics: An Nmr Study, C Carboni

Sultan Qaboos University Journal For Science

The anisotropy of the Ho3+, Tb3+ and Tm3+ rare-earth ions in RFe2 compounds is investigated using the field dependence of the NMR spectra of 169Tm, 159Tb and 165Ho in polycrystalline TmFe2, TbFe2, HoFe2 and related pseudo-binary compounds. The very large hyperfine interaction in these ions dominates the NMR spectrum; the NMR frequencies in the 2 to 7 GHz range provide therefore a measure of the localized moment and its orientation in the crystal field. We compare the NMR measurements to single ion computations that include magnetostriction. KEYWORDS:

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Transform Domain Characterization Of Dual Group Codes Of Cyclic Group Codes Over Elementary Abelian Groups, Adnan Abdulla Zain Apr 2025

Transform Domain Characterization Of Dual Group Codes Of Cyclic Group Codes Over Elementary Abelian Groups, Adnan Abdulla Zain

Sultan Qaboos University Journal For Science

The group of characters of an elementary Abelian group has been used to define duality between its subgroups, which in turn is extended to duality between group codes. The transform domain description of the dual codes of cyclic group codes of length over has been developed in this paper. Several example codes and their duals have been presented also.

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Incidence Matrices Of X-Labled Graphs And An Application, W.S. Jassim Apr 2025

Incidence Matrices Of X-Labled Graphs And An Application, W.S. Jassim

Sultan Qaboos University Journal For Science

In this work, we have made some modifications on the definition of the incidence matrices of a directed graph, to let the incidence matrices to be more confident for X – Labeled graphs. The new incidence matrices are called the incidence matrices of X – Labeled graphs, and we used the new definition to give a computer program for Nickolas`s Algorithm .

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General Screened Coulomb Potential : Nonperturbative Solutions, Lalit Kumar Sharma, Philip Monowe, Samuel Chimidza Apr 2025

General Screened Coulomb Potential : Nonperturbative Solutions, Lalit Kumar Sharma, Philip Monowe, Samuel Chimidza

Sultan Qaboos University Journal For Science

Using nonperturbative solutions, the binding energies for different atoms have been evaluated for the screened Coulomb potentials. The variation of the wavefunction with distance has also been studied. The results obtained are in excellent agreement with earlier calculations.

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Ornithopod And Sauropod Dinosaur Remains From The Maastrichtian Al-Khod Conglomerate, Sultanate Of Oman, Ann S. Schulp, Patrick M.O'Connor, David B. Weishampel, Abdul Razak Al Sayigh, Abdulrahman Al-Harthy, John W.M. Jagt, Axel F. Hartman Apr 2025

Ornithopod And Sauropod Dinosaur Remains From The Maastrichtian Al-Khod Conglomerate, Sultanate Of Oman, Ann S. Schulp, Patrick M.O'Connor, David B. Weishampel, Abdul Razak Al Sayigh, Abdulrahman Al-Harthy, John W.M. Jagt, Axel F. Hartman

Sultan Qaboos University Journal For Science

Fieldwork in the Upper Cretaceous (Maastrichtian) Al-Khod Conglomerates in the Sultanate of Oman led to the discovery of a large bone fragment tentatively identified as a partial distal left humerus of a sauropod and an ornithopod dorsal vertebra. The very fragmentary state of preservation of the dorsal vertebra makes specific attribution difficult, but it shows remarkable similarities to the rhabdodontid dinosaurs Rhabdodon and Zalmoxes.

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Behaviour Of Thermal Degradation Of Some Poly (4-Amino-2,6-Pyrimidinodithiocarbonate) Metal Complexes, Hussein M. Al-Maydama, Ali El-Shekeil, Ashour Al-Karbouly Apr 2025

Behaviour Of Thermal Degradation Of Some Poly (4-Amino-2,6-Pyrimidinodithiocarbonate) Metal Complexes, Hussein M. Al-Maydama, Ali El-Shekeil, Ashour Al-Karbouly

Sultan Qaboos University Journal For Science

The thermal decomposition behaviour of the Fe(II), Co(II) and Ni(II) complexes of poly[4-amino-2,6-pyrimidinodithiocarbamate] has been investigated by thermogravimetric analysis (TGA) at a heating rate of 10°C min-1 under nitrogen. The Coats-Redfern integral method is used to evaluate the kinetic parameters for the successive steps in the decomposition sequence observed in the TGA curves. The processes of thermal decomposition taking place in the three complexes are studied comparatively as the TGA and DTA curves indicate the difference in the thermal decomposition behaviour. The thermal stabilities for the release of the fragments at the successive steps in the sequential decomposition of these …

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Stability And Persistence Of Synchronization In A System With A Diffusive-Time-Lag Coupling, Adu A.M. Wasike Apr 2025

Stability And Persistence Of Synchronization In A System With A Diffusive-Time-Lag Coupling, Adu A.M. Wasike

Sultan Qaboos University Journal For Science

We study synchronization in the framework of invariant manifold theory for systems with a time lag. Normal hyperbolicity and its persistence in infinite dimensional dynamical systems in Banach spaces is applied to give general results on synchronization and its stability.

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Studies Of Surface Area And Pore Structure On Portland Cement Produced In Bajil And Amran, Yemen, A.M. Saad, Abdul-Basit A. Saleh, Fatima A. Al-Kadri, Abdulla S. Babaqi, Abdulla A. Basissa, S.A. Abo El-Enein Apr 2025

Studies Of Surface Area And Pore Structure On Portland Cement Produced In Bajil And Amran, Yemen, A.M. Saad, Abdul-Basit A. Saleh, Fatima A. Al-Kadri, Abdulla S. Babaqi, Abdulla A. Basissa, S.A. Abo El-Enein

Sultan Qaboos University Journal For Science

Portland cement pastes of various porosities were prepared using water/cement ratios of 0.30, 0.35, 0.40, 0.45, 0.50 and 0.55; and were hydrated for various time intervals ranging from 0.021 to 28 days. Pore structure and VL–t plots (plots of volume vs. thickness) of the hardened cement pastes were measured using nitrogen gas as the adsorbate. The results were found to be related to the mechanism of hydration as controlled by the pore system of the hardened pastes. Type ІІ adsorption isotherms of nitrogen were obtained for all hardened cement pastes. The adsorption-desorption isotherms indicated the existence of closed hysteresis loops …

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Simulation Of Decadal Precipitation Over Nairobi In Kenya, John Muthama Nzioka, Manene M. Moses, Ndetei Cornelius Joseph Apr 2025

Simulation Of Decadal Precipitation Over Nairobi In Kenya, John Muthama Nzioka, Manene M. Moses, Ndetei Cornelius Joseph

Sultan Qaboos University Journal For Science

In investigating Kenya rainfall variability and its relationship to other climatic elements it has become imperative to analyze the irregularly distributed rainfall events in time. To meet this requirement, this study used a stepwise regression technique. The study seeks to improve existing rainfall monitoring and prediction in Nairobi. Monthly rainfall data was fitted to several mathematical functions. The best mathematical model which best simulated the March-May (MAM) and October -December (OND) seasonal rainfall over the three stations of analysis was chosen using a stepwise regression technique. The value of R-squared for the best fit was computed to show the percentage …

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On Markov Modulated Mean-Reverting Price-Difference Models, W. P. Malcom, Lakhdar Aggoun, Mohamed Al-Lawati Apr 2025

On Markov Modulated Mean-Reverting Price-Difference Models, W. P. Malcom, Lakhdar Aggoun, Mohamed Al-Lawati

Sultan Qaboos University Journal For Science

In this paper we develop a stochastic model incorporating a double-Markov modulated mean-reversion model. Unlike a price process the basis process X can take positive or negative values. This model is based on an explicit discretisation of the corresponding continuous time dynamics. The new feature in our model is that we suppose the mean reverting level in our dynamics as well as the noise coefficient can change according to the states of some finite-state Markov processes which could be the economy and some other unseen random phenomenon.

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Action Plan For Monitoring, Mitigation And Management Of Harmful Algal Blooms In The Coastal Waters Of Oman, A.Y.A Alkindi, H.M.H. Al-Ghelani, S. Amer, Y.K Al-Akhzami Apr 2025

Action Plan For Monitoring, Mitigation And Management Of Harmful Algal Blooms In The Coastal Waters Of Oman, A.Y.A Alkindi, H.M.H. Al-Ghelani, S. Amer, Y.K Al-Akhzami

Sultan Qaboos University Journal For Science

The Gulf of Oman, an ecologically and economically rich ecosystem, is frequently impacted by occurrences of harmful algal blooms. Recent studies indicate an increase in the number of causative species and harmful impacts. Many red tide incidents in Oman have been found leading to hypoxia. The frequent bloom forming species here are Karenia selliformis, Nitzschia pungens, Prorocentrum arabianum and Trichodesmium erythraeum. We review work carried out in this area, and we propose here a Management Action Plan for not only an effective monitoring system for harmful algal blooms (HABs), but also mitigation of their adverse impacts and rapid response system.

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Review Of Health Information Systems In Oman, Mohammed Elhadi, Ahmed Al-Hosni, Khaled Day, Adbullah Al-Hamadani, Abdulrahman Al-Toqi, Nasser Al-Shamli, Ali Al-Hashmi Apr 2025

Review Of Health Information Systems In Oman, Mohammed Elhadi, Ahmed Al-Hosni, Khaled Day, Adbullah Al-Hamadani, Abdulrahman Al-Toqi, Nasser Al-Shamli, Ali Al-Hashmi

Sultan Qaboos University Journal For Science

This paper is a review of Oman's major Health Information Systems (HISs) and their enabling technologies. The work assesses the scope, functionality, security, and interoperability of the used systems. The review aids in achieving the objectives of HIS systems of improving the global quality of health care, attaining increased coordination between health care providers and consumers, promoting the use of guidelines and policies, and improving the speed of simultaneous access and distribution of medicalrecords and other resources. This paper, which can be considered as a building block towards the development of a nation-wide health care system, studies existing systems and …

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Application Of Neural Networks To Data Mining, Zlatinka Svetoslavova Kovacheva Apr 2025

Application Of Neural Networks To Data Mining, Zlatinka Svetoslavova Kovacheva

Sultan Qaboos University Journal For Science

Data Mining accomplishes nontrivial extraction of implicit, previously unknown, and potentially useful information of data. The aim of data mining is to discover knowledge out of data and present it in a form that is easily comprehensible to humans. Neural Networks are analytic techniques capable of predicting new observations from other observations after executing a process of so-called learning from existing data. Neural Network techniques can also be used as a component of analyses designed to build explanatory models. Now there is neural network software that uses sophisticated algorithms directly contributing to the model building process. The latest developments in …

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Soft Chemistry Routes To New Nanosize Materials, Khaled Melghit Apr 2025

Soft Chemistry Routes To New Nanosize Materials, Khaled Melghit

Sultan Qaboos University Journal For Science

The old classical method for preparing inorganic materials is by the ceramic route or solid state reaction. It consists of mixing the starting materials at an elevated temperature. This method has been used for preparing numerous new materials until today. Three decades ago, the materials science community was aware of soft chemistry synthesis or chimie douce, especially with the emergence of nanotechnology field. Instead of the classical method, which involves high temperature, soft chemistry techniques use lower temperatures. In general, starting materials are dissolved in a liquid phase and different parameters such as pH, temperature and reaction time are adjusted …

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Kähler Manifolds Positive Ricci Curvature, Boudjemaa Anchouche Apr 2025

Kähler Manifolds Positive Ricci Curvature, Boudjemaa Anchouche

Sultan Qaboos University Journal For Science

The aim of this paper is to give an overview of some results obtained in the field of Kähler manifolds of positive Ricci curvature.

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An Overview Of Some Practical Quasi-Newton Methods For Unconstrained Optimization, M. Al-Baali, H. Khalfan Apr 2025

An Overview Of Some Practical Quasi-Newton Methods For Unconstrained Optimization, M. Al-Baali, H. Khalfan

Sultan Qaboos University Journal For Science

Quasi-Newton methods are among the most practical and efficient iterative methods for solving unconstrained minimization problems. In this paper we give an overview of some of these methods with focus primarily on the Hessian approximation updates and modifications aimed at improving their performance.

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Experimental Design For Nonlinear Problems, K.M Abdelbasit Apr 2025

Experimental Design For Nonlinear Problems, K.M Abdelbasit

Sultan Qaboos University Journal For Science

Experimental designs for nonlinear problems have to a large extent relied on optimality criteria originally proposed for linear models. Optimal designs obtained for nonlinear models are functions of the unknown model parameters. They cannot, therefore, be directly implemented without some knowledge of the very parameters whose estimation is sought. The natural way is to adopt a sequential or Bayesian approach. Another is to utilize available estimates or guesses. In this article we provide a brief historical account of the subject, discuss optimality criteria commonly used for nonlinear models, the associated problems and ways of overcoming them. We also discuss issues …

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Screening Of Antioxidant And Radical Scavenging Activities Of Some Omani Medicinal Plants, Saleh Al-Busafi, Mubarak Al-Riyami, Khadija Al-Ouwaisi, Abdulkhader Hisham Apr 2025

Screening Of Antioxidant And Radical Scavenging Activities Of Some Omani Medicinal Plants, Saleh Al-Busafi, Mubarak Al-Riyami, Khadija Al-Ouwaisi, Abdulkhader Hisham

Sultan Qaboos University Journal For Science

n-Butanol extracts of nine medicinal plants, Cressa cretica, Ziziphus spina-christ, Acacia tortilis, Tephrosia haussknechti, Aristolochiae bracteolata, Citrullus colocynthis, Teucrium mascatense, Rhazya stricta and Nerium oleander, found in Oman were screened for their antioxidant activity using phosphomolybdenum complex assays and their radical scavenging activity using DPPH assays. Ocimumi basilicum, a plant with well documented antioxidant activity, was used as a reference. A. tortilis, and T. haussknechti extracts possessed very high antioxidant activity (AOA) and high radical scavenging activity (RSA).

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The Direction Of Spontaneous Magnetisation Of Lanthanide Ions At A Site Of Cubic Symmetry, C. Carboni, E. Al-Abry, S. Arafin Apr 2025

The Direction Of Spontaneous Magnetisation Of Lanthanide Ions At A Site Of Cubic Symmetry, C. Carboni, E. Al-Abry, S. Arafin

Sultan Qaboos University Journal For Science

The zero temperature direction of spontaneous magnetisation of lanthanide ions at a site of cubic symmetry is investigated as a function of the electrostatic and magnetic interactions. For all the values of J between J = 3 and J = 8, two-dimensional diagrams giving the orientation of spontaneous magnetisation are obtained as a function of the parameters R representing the relative strength of the magnetic to electrostatic interaction and the parameter x representing the relative strength of the fourth to the sixth order terms in the crystal field. The boundaries between regions of the parameter space with different directions of …

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Limits Of The Efficiency Of Imaging With Obstructing Apertures, A.T. Mohammed Apr 2025

Limits Of The Efficiency Of Imaging With Obstructing Apertures, A.T. Mohammed

Sultan Qaboos University Journal For Science

Two-dimensional numerical solutions are carried out to asses the quality of obstructing apertures in terms of the diffraction limited resolution. This include the quality of the point spread function (psf), the modulation transfer function (MTF), and an image of double lines. These are average intensity of the psf (AI), maximum intensity of the psf,(MI), full width at half maximum of the psf (FW) average frequency components of MTF (AFC), and average side loops of an image of a double lines. The results indicate that the separation of the two lines becomes recognizable using central obstruction of radius equal to or …

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A Knowledge-Induced Operator Model, M.A. Choudhury, S.I. Zaman, Yaqoub Al-Nassar Apr 2025

A Knowledge-Induced Operator Model, M.A. Choudhury, S.I. Zaman, Yaqoub Al-Nassar

Sultan Qaboos University Journal For Science

Learning systems are in the forefront of analytical investigation in the sciences. In the social sciences they occupy the study of complexity and strongly interactive world-systems. Sometimes they are diversely referred to as symbiotics and semiotics when studied in conjunction with logical expressions. In the mathematical sciences the methodology underlying learning systems with complex behavior is based on formal logic or systems analysis. In this paper relationally learning systems are shown to transcend the space-time domain of scientific investigation into the knowledge dimension. Such a knowledge domain is explained by pervasive interaction leading to integration and followed by continuous evolution …

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A Procedure To Correct Errors In Depth Estimation From Slope Hale Slope Method, Fitian R. Al-Rawi, Ali M. Al-Rahim Apr 2025

A Procedure To Correct Errors In Depth Estimation From Slope Hale Slope Method, Fitian R. Al-Rawi, Ali M. Al-Rahim

Sultan Qaboos University Journal For Science

The novel method named slope half slope for depth estimation of the causative magnetic field proposed by Peters (1949) has been investigated to determine the possible percent errors in depth estimation to magnetic sources situated at different latitudes. A sequence of models represented by thick dykes with various depths and with different values of field inclination (0 to 90°) has been used to estimate the percentage errors for the different inclination values. A procedure to correct the errors in depth estimate has been discussed. The calculated percent errors range between positive and negative values for the same angle of inclination …

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Synchronization And Persistence In Diffusively Coupled Lattice Oscillators, Adu A.M. Wasike, K.T. Rotich Apr 2025

Synchronization And Persistence In Diffusively Coupled Lattice Oscillators, Adu A.M. Wasike, K.T. Rotich

Sultan Qaboos University Journal For Science

We consider the synchronization and persistence of a system of identical lattice oscillators that are diffusively coupled to their nearest neighbours. Each subsystem has a compact global attractor. This is done in the framework of invariant manifold theory. Normal hyperbolicity and its persistence are applied to obtain general conditions for the stability and robustness of the synchronization manifold. AMS(MOS) Subject classifications: 37C80, 37D10.

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Evaluation Of Seminal Fluid Parameters, Reproductive Hormones And Testicular Biopsy For Non-Obstructive Azoospermic Patients With Sertoli Cell Only Syndrome, Naso S. Qhraman, Muhammad-Baqir M-R. Fakhrildin, Dhaher H. Bra Apr 2025

Evaluation Of Seminal Fluid Parameters, Reproductive Hormones And Testicular Biopsy For Non-Obstructive Azoospermic Patients With Sertoli Cell Only Syndrome, Naso S. Qhraman, Muhammad-Baqir M-R. Fakhrildin, Dhaher H. Bra

Sultan Qaboos University Journal For Science

The aims of this study were (i) to determine the seminal fluid parameters, levels of serum reproductive hormones, testicular size and diameter of seminiferous tubules depending on multiple testicular biopsies from non-obstructive azoospermic (NOA) patients, and (ii) to assess the effect of smoking on concentrations of serum reproductive hormones. Thirty four NOA patients were involved in the present study. The selection of patients was based on an average of 2 pelleting seminal analysis, reproductive hormones profile and diagnostic testicular biopsy. A detailed questionnaire was used to obtain a thorough history from the patients. The results of this study showed that …

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Investigation Of Facies Types And Associations Of Kuhlan Red Bed Formation In Nw Yemen: A New Hypothesis For Origin And Depositional Environment, Mohammed A. Al-Wosabi, Sa’Ad Z. Al-Mashaikie Apr 2025

Investigation Of Facies Types And Associations Of Kuhlan Red Bed Formation In Nw Yemen: A New Hypothesis For Origin And Depositional Environment, Mohammed A. Al-Wosabi, Sa’Ad Z. Al-Mashaikie

Sultan Qaboos University Journal For Science

Varieties of thirteen facies types were recognized in the Kuhlan Formation represented by red bed siliciclastic sequences of argillaceous sediments. Examination of the Kuhlan stratigraphic column included sequence relationships, lithology, sedimentary characters, structures and petrography of the dominant rock types. These facies types are grouped in three distinct associations of facies. The lower unit A comprises association of facies (Distal turbidites) represented by alternates of turbidity sequences including sandstone, siltstone and thick shale beds. These facies types confirm a regressive depositional environment in deep marine shelf conditions. There are three facies types which are identified as massive sandstone, cross-bedded sandstone …

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The Time Evolution Of A Constant Mass Of Air Pollutant Emitted By A Point Source, M.H.A. Hassan, I.A. Eltayeb Apr 2025

The Time Evolution Of A Constant Mass Of Air Pollutant Emitted By A Point Source, M.H.A. Hassan, I.A. Eltayeb

Sultan Qaboos University Journal For Science

The transient behaviour of a constant mass (i.e. a blob) of pollutant released from a point source at a height, , above ground level at time is studied. The time dependent atmospheric diffusion equation in the presence of diffusion in both horizontal and vertical directions is used to model the problem. The model is found to be governed by an initial-boundary-value problem for the concentration of the pollutant. The solution is obtained in closed form using integral transform methods. The solution is illustrated graphically using appropriate numerical integrations. As time passes, the pollutant blob moves with a central point of …

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Fabric Preserving And Fabric Destroying Dolomitization: A Case Of Seawater Dolomitization, Alham Jassim Al-Langawi Apr 2025

Fabric Preserving And Fabric Destroying Dolomitization: A Case Of Seawater Dolomitization, Alham Jassim Al-Langawi

Sultan Qaboos University Journal For Science

This study is based on field, petrographic and geochemical investigations of Hajar Supergroup autochthonous rocks: Ruus Al Jibal Group- Musandam Peninsula, and Akhdar Group- Jebel Akhdar, Oman and U.A.E., and para-autochthonous Maqam Formation-Sumeini Group-Jebel Sumeini-U.A.E. Petrographic evidence indicates that the rocks were deposited in a shallow marine shelf environment, particularly tidal flat, lagoon, reef, back-reef and shoal environments that were part of the Arabian Platform during Permian and Triassic times. However, they are almost entirely dolomitized and the rocks show different petrographic features ranging from perfect preservation of original texture by mimetic dolomitization to complete obliteration and destruction of the …

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Specific Heat Of Dy.40 Cu.37 Y.23 Amorphous Alloy At Low Temperatures, K.A. Mohammed Apr 2025

Specific Heat Of Dy.40 Cu.37 Y.23 Amorphous Alloy At Low Temperatures, K.A. Mohammed

Sultan Qaboos University Journal For Science

The low temperature specific heat of the magnetic Dy0.40Cu0.37Y0.23 amorphous alloy have been investigated in the temperature range 2 to 50 K. The magnetic contributions to the specific heat, magnetic entropy changes, ordering temperatures and the effective magnetic spin have been estimated for this magnetic amorphous alloy. The magnetic specific heat show broad anomaly at a certain temperature, Tm of about 28 K. The value of Tm is higher than Tf (=23.5 K) determined from low field ac susceptibility measurements. The magnetic entropy changes between 0 K and Tm are estimated to be 84 % of the maximum theoretical value. …

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Two New Measures Of Fuzzy Divergence And Their Properties, Om Parkash, P.K. Sharma, Subhash Kumar Apr 2025

Two New Measures Of Fuzzy Divergence And Their Properties, Om Parkash, P.K. Sharma, Subhash Kumar

Sultan Qaboos University Journal For Science

Several measures of directed divergence and their corresponding measures of fuzzy divergence are available in the exiting literature. Two new measures of fuzzy divergence have been developed and their desirable properties have been discussed.

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