Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 31921 - 31950 of 715204

Full-Text Articles in Entire DC Network

On Regression Estimators Using Extreme Ranked Set Samples, Hani M. Samawi, Ahmed Y.A. Al-Samarraie, Obaid M. Al-Saidy Apr 2025

On Regression Estimators Using Extreme Ranked Set Samples, Hani M. Samawi, Ahmed Y.A. Al-Samarraie, Obaid M. Al-Saidy

Sultan Qaboos University Journal For Science

Regression is used to estimate the population mean of the response variable, , in the two cases where the population mean of the concomitant (auxiliary) variable, , is known and where it is unknown. In the latter case, a double sampling method is used to estimate the population mean of the concomitant variable. We invesitagate the performance of the two methods using extreme ranked set sampling (ERSS), as discussed by Samawi et al. (1996). Theoretical and Monte Carlo evaluation results as well as an illustration using actual data are presented. The results show that if the underlying joint distribution of …

Go to article

Recursive Estimation Of A Discrete-Time Lotka-Volterra Predator-Prey Model, Lakhdar Aggoun Apr 2025

Recursive Estimation Of A Discrete-Time Lotka-Volterra Predator-Prey Model, Lakhdar Aggoun

Sultan Qaboos University Journal For Science

In this paper, using hidden Markov models, we estimate the number of individuals in a two-species (predator-prey) animal population using partial information provided by the so-called capture-recapture technique. Random samples of individuals are captured, tagged in some way and released. After some time other random samples are taken and the marked individuals are observed. Using this information, we estimate (recursively) the sizes of the two populations. Also, using the Expectation Maximization (EM) algorithm, the parameters of the model are updated.

Go to article

Realization Of A Simplified Controllability Computation Procedure: A Matlab- Simulink Based Tool, Ali Al-Lawati, Afaq Ahmed Apr 2025

Realization Of A Simplified Controllability Computation Procedure: A Matlab- Simulink Based Tool, Ali Al-Lawati, Afaq Ahmed

Sultan Qaboos University Journal For Science

With the use of MATLAB-SIMULINK a simple tool has been developed to compute the controllabilities of nodes as well as branches of digital system networks. The primary advantage of this tool may be for such conditions where the study of controllability analysis of a system with different possible designs is required to give an optimal design solution. The ease of network simulation procedures together with the simple methodologies for inputting the different assigned parameters to the respective elements of the system in dynamic environments, are additional attributes of this tool.

Go to article

On Group Codes Over Elementary Abelian Groups, Adnan A. Zain Apr 2025

On Group Codes Over Elementary Abelian Groups, Adnan A. Zain

Sultan Qaboos University Journal For Science

For group codes over elementary Abelian groups we present definitions of the generator and the parity check matrices, which are matrices over the ring of endomorphism of the group. We also lift the theorem that relates the parity check and the generator matrices of linear codes over finite fields to group codes over elementary Abelian groups. Some new codes that are MDS, self-dual, and cyclic over the Abelian group with four elements are given.

Go to article

Step-Wise Group Screening Designs With Unequal A-Priori Probabilities And Errors In Observations, M.M. Manene Apr 2025

Step-Wise Group Screening Designs With Unequal A-Priori Probabilities And Errors In Observations, M.M. Manene

Sultan Qaboos University Journal For Science

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.

Go to article

A Monte Carlo Method For Low Pressure Radio Frequency Discharges, Lahouaria Settaouti, Abderrahmane Settaouti Apr 2025

A Monte Carlo Method For Low Pressure Radio Frequency Discharges, Lahouaria Settaouti, Abderrahmane Settaouti

Sultan Qaboos University Journal For Science

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 …

Go to article

Characterizations Of K- Semimetric Spaces, Abdul M. Mohamad Apr 2025

Characterizations Of K- Semimetric Spaces, Abdul M. Mohamad

Sultan Qaboos University Journal For Science

In this paper, we prove, for a space X, the following are equivalent:1. X is a D1 space with a regular-Gδ-diagonal,2. X is a D2 space with a regular-Gδ-diagonal, 3. X is a semi-developable space with Gδ (3) -diagonal, 4. X is a D1-space with a Gδ(3)-diagonal, 5. X is a D2 -space with a Gδ(3)-diagonal, 6. X is a q, -space with a G*δ (2)-diagonal, 7. X is a semi-developable space with G*δ (2)-diagonal, 8. X is a semimetrizable, c-stratifiable space, 9. X is a c-Nagata -space, 10. X is a K-semimetrizable.

Go to article

Synchronization And Oscillator Death In Diffusively Coupled Lattice Oscillators, Adu A.M. Wasike Apr 2025

Synchronization And Oscillator Death In Diffusively Coupled Lattice Oscillators, Adu A.M. Wasike

Sultan Qaboos University Journal For Science

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.

Go to article

Steady State Analysis Of A Upfc As Voltage Regulator For Optimal Position In The Transmission Line, S. Ali Al-Mawsawi, Mohammed R. Qader Apr 2025

Steady State Analysis Of A Upfc As Voltage Regulator For Optimal Position In The Transmission Line, S. Ali Al-Mawsawi, Mohammed R. Qader

Sultan Qaboos University Journal For Science

It has recently been illustrated that the Unified Power Flow Controller (UPFC) installation location plays an important role in effecting nonlinearly in the UPFC steady state performance of the system. A Pulse Width Modulation (PWM) based on UPFC as a voltage regulator is modeled and analyzed to investigate the optimal position in the transmission line. From the study made in this paper, it is shown that the location of UPFC plays a significant part in effecting nonlinearly. It is also found from the simulation results that the distribution of the active and reactive power flows can be controlled by varying …

Go to article

Metrization Of Weakly Developable Spaces, Abdul M. Mohamad Apr 2025

Metrization Of Weakly Developable Spaces, Abdul M. Mohamad

Sultan Qaboos University Journal For Science

In this note, we present metrization of weak developability.

Go to article

A Fluid Film Squeezed Between Two Parallel Plane Surfaces Subject To Normal Oscillations, E. A. Hamza Apr 2025

A Fluid Film Squeezed Between Two Parallel Plane Surfaces Subject To Normal Oscillations, E. A. Hamza

Sultan Qaboos University Journal For Science

We study the motion which results when a fluid film is squeezed between two parallel surfaces in relative motion. Particular attention is given to the special case where one surface is fixed and the other is impulsively accelerated from a state of rest to a state of sinusoidal oscillations in a direction normal to its plane. In addition to the presentation of analytic solutions which are based on the regular perturbation technique and on the linearised analysis of the resulting nonlinear partial differential equation, a numerical solution of the full nonlinear equation based on a finite-difference scheme is obtained. The …

Go to article

Periodic Solutions Of A System Of Delay Differential Equations For A Small Delay, Adu A.M. Wasike, Wandera Ogana Apr 2025

Periodic Solutions Of A System Of Delay Differential Equations For A Small Delay, Adu A.M. Wasike, Wandera Ogana

Sultan Qaboos University Journal For Science

We prove the existence of an asymptotically stable periodic solution of a system of delay differential equations with a small time delay t > 0. To achieve this, we transform the system of equations into a system of perturbed ordinary differential equations and then use perturbation results to show the existence of an asymptotically stable periodic solution. This approach is contingent on the fact that the system of equations with t = 0 has a stable limit cycle. We also provide a comparative study of the solutions of the original system and the perturbed system. This comparison lays the ground for …

Go to article

Deletion Designs, Michael Kamau Gachii, John Wycliff Odhiambo, Anne Wachira Apr 2025

Deletion Designs, Michael Kamau Gachii, John Wycliff Odhiambo, Anne Wachira

Sultan Qaboos University Journal For Science

In this paper a method of constructing a class of flexible single replicate factorial designs in blocks is given. Simple expressions for calculating loss of information on low order interactions is presented.

Go to article

Regression Estimator Using Double Ranked Set Sampling, Hani M. Samawi, Eman M. Tawalbeh Apr 2025

Regression Estimator Using Double Ranked Set Sampling, Hani M. Samawi, Eman M. Tawalbeh

Sultan Qaboos University Journal For Science

The performance of a regression estimator based on the double ranked set sample (DRSS) scheme, introduced by Al-Saleh and Al-Kadiri (2000), is investigated when the mean of the auxiliary variable X is unknown. Our primary analysis and simulation indicates that using the DRSS regression estimator for estimating the population mean substantially increases relative efficiency compared to using regression estimator based on simple random sampling (SRS) or ranked set sampling (RSS) (Yu and Lam, 1997) regression estimator. Moreover, the regression estimator using DRSS is also more efficient than the naïve estimators of the population mean using SRS, RSS (when the correlation …

Go to article

Design Of All Optical Packet Switching Networks, Hussein T. Mouftah Apr 2025

Design Of All Optical Packet Switching Networks, Hussein T. Mouftah

Sultan Qaboos University Journal For Science

Optical switches and wavelength converters are recognized as two of the most important DWDM system components in future all-optical networks. Optical switches perform the key functions of flexible routing, reconfigurable optical cross-connect (OXC), network protection and restoration, etc. in optical networks. Wavelength Converters are used to shift one incoming wavelength to another outgoing wavelength when this needs to be done. Always residing in optical switches, they can effectively alleviate the blocking probability and help solve contention happening at the output port of switches. The deployment of wavelength converters within optical switches provides robust routing, switching and network management in optical …

Go to article

Biological Effects Of Em Radiations From Mobile Phones, Adel A. Ali, Ahmed M. Al-Naamany Apr 2025

Biological Effects Of Em Radiations From Mobile Phones, Adel A. Ali, Ahmed M. Al-Naamany

Sultan Qaboos University Journal For Science

Direct health effects could result following exposure to RF by thermal (heating effects). Recent Studies have shown that there are public fears on effects that can be caused mainly by holding mobile phones close to the body, or as a result of possible non-thermal effects from both phones and base stations. This paper offers an overview on the biological effects of electromagnetic radiation caused by mobile phones. Exposures of individuals to RF radiation from these sources will depend upon their proximity and may be above those from mobile phone base stations, although still well below guidelines. From a review of …

Go to article

Simulation Of M-Sequence’S Properties Through Matlab-Simulink, A. Ahmad, M. J. Al-Mushrafi, S. Al-Busaidi Apr 2025

Simulation Of M-Sequence’S Properties Through Matlab-Simulink, A. Ahmad, M. J. Al-Mushrafi, S. Al-Busaidi

Sultan Qaboos University Journal For Science

Based on an analytical study of the theory of m-sequences, a tool is developed to facilitate practicing engineers to either generate m-sequence for its application, or to test applied m-sequence, or both. The developed test–kit simulates all the properties of m-sequences including number of 1s and 0s, the run lengths, pulse periods as well as autocorrelation properties. This simplified tool is developed using MATLAB–SIMULINK with required codes as well as desired blocks. The model is cost-effective and the output files of the generated SIMULINK models can be utilized in any software program or simulation procedures.

Go to article

Development And Application Of Back-Propagation-Based Artificial Neural Network Models In Solving Engineering, Saleh Mohammed Al-Alawi Apr 2025

Development And Application Of Back-Propagation-Based Artificial Neural Network Models In Solving Engineering, Saleh Mohammed Al-Alawi

Sultan Qaboos University Journal For Science

Artificial Neural Networks (ANNs) are computer software programs that mimic the human brain's ability to classify patterns or to make forecasts or decisions based on past experience. The development of this research area can be attributed to two factors, sufficient computer power to begin practical ANN-based research in the late 1970s and the development of back-propagation in 1986 that enabled ANN models to solve everyday business, scientific, and industrial problems. Since then, significant applications have been implemented in several fields of study, and many useful intelligent applications and systems have been developed. The objective of this paper is to generate …

Go to article

Experimental Modeling Of Monolithic Resistors For Silicon Ics With A Robust Optimizer-Driving Scheme, Philippe Leduc, Didier Magnon, Fabrice Guitton Apr 2025

Experimental Modeling Of Monolithic Resistors For Silicon Ics With A Robust Optimizer-Driving Scheme, Philippe Leduc, Didier Magnon, Fabrice Guitton

Sultan Qaboos University Journal For Science

Today, an exhaustive library of models describing the electrical behavior of integrated passive components in the radio-frequency range is essential for the simulation and optimization of complex circuits. In this work, a preliminary study has been done on Tantalum Nitride (TaN) resistors integrated on silicon, and this leads to a single p-type lumped-element circuit. An efficient extraction technique will be presented to provide a computer-driven optimizer with relevant initial model parameter values (the "guess-timate"). The results show the unicity in most cases of the lumped element determination, which leads to a precise simulation of self-resonant frequencies.

Go to article

Design Of Ultra Fast Rce Photodetectors For Optical Communications Systems, Joseph A. Jervase, Hadj Bourdoucen Apr 2025

Design Of Ultra Fast Rce Photodetectors For Optical Communications Systems, Joseph A. Jervase, Hadj Bourdoucen

Sultan Qaboos University Journal For Science

Two key parameters for RCE photodetectors that govern their suitability for ultrafast optical communication systems are considered. These are the quantum efficiency and the bandwidth efficiency product. A closed analytical form has been derived for quantum efficiency, which incorporates the structural parameters of the photodetector. Based on the simulation results, an optimization and design procedure for these photodetectors has been developed.

Go to article

Characteristic And Non-Characteristic Harmonics, Harmonic Cancellations And Relevant International Standards In Variable Speed Drives, Syed M. Islam Apr 2025

Characteristic And Non-Characteristic Harmonics, Harmonic Cancellations And Relevant International Standards In Variable Speed Drives, Syed M. Islam

Sultan Qaboos University Journal For Science

This paper will present a review of characteristic harmonics in both single phase and three phase drive front end rectifiers, discuss recent research findings in identifying sources and production of non-characteristic harmonics and amplification of harmonic levels when the front end rectifiers are fed from non-ideal supply conditions. Significant amount of triplens may be generated due to unbalances in utility supply voltage wave form and anticipated harmonic levels may vary widely. The paper will also discuss international harmonic standards such as the AS 2279, IEEE 519, and IEC 61000 series applicable to rectifier loads. Finally, the paper will present techniques …

Go to article

Matlab And Pspice Dynamic Model Of Axial-Field Permanent-Magnet Motor, A.H. Al-Badi, A. Gastli Apr 2025

Matlab And Pspice Dynamic Model Of Axial-Field Permanent-Magnet Motor, A.H. Al-Badi, A. Gastli

Sultan Qaboos University Journal For Science

In this paper a dynamic model of the axial-field, permanent-magnet machine will be discussed. The model may be used to study the transient response with the machine operating as a motor or as a generator. Experimental results are compared with Matlab/Simulink and Pspice predictions for a number of conditions, including the complete starting transient. Excellent correlation is obtained which validated both modeling approaches.

Go to article

Towards Formulation Of A Complex Binary Number System, Tariq Jamil, David Blest, Amer Al-Habsi Apr 2025

Towards Formulation Of A Complex Binary Number System, Tariq Jamil, David Blest, Amer Al-Habsi

Sultan Qaboos University Journal For Science

For years complex numbers have been treated as distant relatives of real numbers despite their widespread applications in the fields of electrical and computer engineering. These days computer operations involving complex numbers are most commonly performed by applying divide-and-conquer technique whereby each complex number is separated into its real and imaginary parts, operations are carried out on each group of real and imaginary components, and then the final result of the operation is obtained by accumulating the individual results of the real and imaginary components. This technique forsakes the advantages of using complex numbers in computer arithmetic and there exists …

Go to article

A Finite Volume Runge-Kutta Ellam Method For The Solution Of Advection Diffusion Equations, Mohammed Al-Lawatia, Robert C. Sharpley, Hong Wang Apr 2025

A Finite Volume Runge-Kutta Ellam Method For The Solution Of Advection Diffusion Equations, Mohammed Al-Lawatia, Robert C. Sharpley, Hong Wang

Sultan Qaboos University Journal For Science

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.

Go to article

Approximating The Tail Probability Of The T-Distribution: A Bayesian Approach, Mohammad Fraiwan Al-Saleh Apr 2025

Approximating The Tail Probability Of The T-Distribution: A Bayesian Approach, Mohammad Fraiwan Al-Saleh

Sultan Qaboos University Journal For Science

A Bayesian technique is used to approximate the tail probability of the t-distribution. A set of upper and lower bounds are obtained for this probability. Based on their simplicity and accuracy, these bounds are very adequate to use. Some members of these bounds are compared to some existing approximations. The possibility of using this new procedure for some other distributions is explored.

Go to article

State-Of-The-Art-Review Of Collapsible Soils, A. A. Al-Rawas Apr 2025

State-Of-The-Art-Review Of Collapsible Soils, A. A. Al-Rawas

Sultan Qaboos University Journal For Science

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 …

Go to article

A Comprehensive Review Of Boundary Integral Formulations Of Acoustic Scattering Problems, S.I. Zaman Apr 2025

A Comprehensive Review Of Boundary Integral Formulations Of Acoustic Scattering Problems, S.I. Zaman

Sultan Qaboos University Journal For Science

This is a review presenting an overview of the developments in boundary integral formulations of the acoustic scattering problems. Generally, the problem is formulated in one of two ways viz. Green’s representation formula, and the Layer-theoretic formulation utilizing either a simple-layer or a double-layer potential. The review presents and expounds the major contributions in this area over the last four decades. The need for a robust and improved formulation of the exterior scattering problem (Neumann or Dirichlet) arose due to the fact that the classical formulation failed to yield a unique solution at (acoustic) wave-numbers which correspond to eigenvalues (eigenfrequencies) …

Go to article

Modeling Flow And Transport In Unsaturated Porous Media: A Review, H.H. Al-Barwani, M. Al-Lawatia, E. Balakrishnan, A. Purnama Apr 2025

Modeling Flow And Transport In Unsaturated Porous Media: A Review, H.H. Al-Barwani, M. Al-Lawatia, E. Balakrishnan, A. Purnama

Sultan Qaboos University Journal For Science

Underground water is a vital natural resource and every effort should be made to understand ways and means of efficiently using and managing it. The unsaturated zone, bounded at its top by the land surface and below by the water table, is the region through which water, together with pollutant carried by the water, infiltrates to reach the groundwater. Therefore, various processes occurring within the unsaturated zone play a major role in determining both the quality and quantity of water recharging into the groundwater. Classical methods of predicting water flow and contaminant transport processes in unsaturated porous media are generally …

Go to article

Electromagnetic Modeling Of The Propagation Characteristics Of Satellite Communications Through Composite Precipitation Layers, Part1: Mathematical Formulation, H.M. Al-Rizzo, And Department Of Electrical And Electronics Engineering, College Of Engineering, Sultan Qaboos University, P.O. Box 33, Al Khod 123, Muscat, Sultanate Of Oman., H.T. Al-Hafid, J.M. Tranquilla Apr 2025

Electromagnetic Modeling Of The Propagation Characteristics Of Satellite Communications Through Composite Precipitation Layers, Part1: Mathematical Formulation, H.M. Al-Rizzo, And Department Of Electrical And Electronics Engineering, College Of Engineering, Sultan Qaboos University, P.O. Box 33, Al Khod 123, Muscat, Sultanate Of Oman., H.T. Al-Hafid, J.M. Tranquilla

Sultan Qaboos University Journal For Science

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 …

Go to article

Voltage Stability Analysis Of Muscat Power System During Summer Weather Conditions, K. Ellithy, A. Gastli, S. Al-Alawi, A. Al-Hinai, Z. Al-Abri Apr 2025

Voltage Stability Analysis Of Muscat Power System During Summer Weather Conditions, K. Ellithy, A. Gastli, S. Al-Alawi, A. Al-Hinai, Z. Al-Abri

Sultan Qaboos University Journal For Science

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 …

Go to article

First Prev Next Last