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 70891 - 70920 of 1519340

Full-Text Articles in Entire DC Network

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

Intelligent Techniques For Power Systems Vulnerability Assessment, Mohamed A. El-Sharkawi Apr 2025

Intelligent Techniques For Power Systems Vulnerability Assessment, Mohamed A. El-Sharkawi

Sultan Qaboos University Journal For Science

With power grids considered national security matters, the reliable operation of the system is of top priority to utilities. This concern is amplified by the utility’s deregulation, which increases the system’s openness while simultaneously decreasing the applied degree of control. Vulnerability Assessment (VA) deals with the power system’s ability to continue to provide service in case of an unforeseen catastrophic contingency. Such contingencies may include unauthorized tripping, breaks in communication links, sabotage or intrusion by external agents, human errors, natural calamities and faults. These contingencies could lead to a disruption of service to part or all of the system. The …

Go to article

E-Business Development : A Strategic View, Saad Haj Bakry Apr 2025

E-Business Development : A Strategic View, Saad Haj Bakry

Sultan Qaboos University Journal For Science

E-business is becoming increasingly important for countries, organizations and individuals, as it gives them efficiency, and as it integrates them together, and with the world at large. This paper aims at providing a strategic view of the development of e-business. It starts by identifying e-business, and by reviewing its current progress. It then presents an e-business development profile, that defines the various elements associated with it. Based on the profile, the paper then provides future development guidelines, and identifies recommended plans.

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

Information Security Risks On A University Campus, Amer A. Al-Rawas, S. Millmore Apr 2025

Information Security Risks On A University Campus, Amer A. Al-Rawas, S. Millmore

Sultan Qaboos University Journal For Science

This paper is concerned with issues relating to security in the provision of information systems (IS) services within a campus environment. It is based on experiences with a specific known environment; namely Sultan Qaboos University. In considering the risks and challenges that face us in the provision of IS services we need to consider a number of interwoven subject areas. These are: the importance of information to campus communities, the types of information utilised, and the risk factors that relate to the provision of IS services. Based on our discussion of the risk factors identified within this paper, we make …

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

Comparative Study Of Load Frequency Controller Designs For Interconnected Power Systems, M. Albadi, A. Awladthani, B. Alomeiri, K. Ellithy Apr 2025

Comparative Study Of Load Frequency Controller Designs For Interconnected Power Systems, M. Albadi, A. Awladthani, B. Alomeiri, K. Ellithy

Sultan Qaboos University Journal For Science

This paper presents a comparative study of three different load frequency (LF) controller designs for interconnected power systems. They are the conventional integral controller, a controller based on the pole-placement technique, and a controller based on optimal control law. Each controller has been designed to improve the dynamic response of system frequency and tie line power flow under a sudden load change. The results obtained using a MATALB computer program show the effectiveness of the LF controller designs. The results also show that the combined optimal controller with conventional integral controller can provide good damping to the system and reduce …

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

Assessment Of The Electrical Systems Interconnection In The Arab World, M.H. Abderrazzaq Apr 2025

Assessment Of The Electrical Systems Interconnection In The Arab World, M.H. Abderrazzaq

Sultan Qaboos University Journal For Science

The international trend of interconnecting electric power systems has two dimensions; economical and technical. Electric power systems in the Arab World are not only eligible, but in need for having a unified power grid. The potentials, status and conditions of the existing and future interconnections in this region are overviewed. The development of the six countries interconnection project, including the completed phase of Jordan-Egypt submarine link, is discussed in details. Finally, the main technical problems, which either faced the first stages of the project or expected to face the interconnected systems in the subsequent stages, are highlighted.

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

A Modified Asynchronous Transfer Mode Fuzzy Policer, M.R.M. Rizk, H. Rashwan, A. Abdel Aziz Apr 2025

A Modified Asynchronous Transfer Mode Fuzzy Policer, M.R.M. Rizk, H. Rashwan, A. Abdel Aziz

Sultan Qaboos University Journal For Science

A Modified Fuzzy policer for Asynchronous Transfer Mode is introduced. In a preceding fuzzy policer model the time window (time interval where ATM cells are accepted in the policer) is not synchronized with the source activity. In the proposed one, the time windows are not consecutive but are triggered by the first arriving cell. The modified policer gives good improvement to the selectivity, and minimizes the congestion over the path. This improvement can be significant for multiple channels.

Go to article

Joint Symbol And Frame Synchronization For Direct- Detection Optical Communication Systems, Eesa M. Bastaki, Harry H. Tan Apr 2025

Joint Symbol And Frame Synchronization For Direct- Detection Optical Communication Systems, Eesa M. Bastaki, Harry H. Tan

Sultan Qaboos University Journal For Science

The problem of joint symbol and frame synchronization in direct-detection optical PPM communication systems under the assumption of known slot timing is considered here. The optimum maximum-likelihood (ML) and sub-optimum rules for this joint symbol and frame synchronization problem are derived. The reason of Georghiades's (1985) incorrect ML rule is discussed in this paper.

Go to article

Analysis Of Electrical Stresses In Ac Switches Used For Control Of Small Power Motors Present In Household Appliances, Yves Raingeaud, Franck Galtie, Laurent Gonthier, Jean Baillou Apr 2025

Analysis Of Electrical Stresses In Ac Switches Used For Control Of Small Power Motors Present In Household Appliances, Yves Raingeaud, Franck Galtie, Laurent Gonthier, Jean Baillou

Sultan Qaboos University Journal For Science

This paper describes a study on electric and thermal stresses induced in bidirectional switches used for control of small power motors present in household appliances, in order to find out the possible weakness of the current solution generally made of a triac and to determine the requirements for new dedicated devices in the ASDTM technology. First, a behavioral analysis of these motors must be performed and the interactions between the switch and the load have to be well defined.

Go to article

Robust Longitudinal Aircraft- Control Based On An Adaptive Fuzzy-Logic Algorithm, Abdel- Latif Elshafei Apr 2025

Robust Longitudinal Aircraft- Control Based On An Adaptive Fuzzy-Logic Algorithm, Abdel- Latif Elshafei

Sultan Qaboos University Journal For Science

To study the aircraft response to a fast pull-up manoeuvre, a short period approximation of the longitudinal model is considered. The model is highly nonlinear and includes parametric uncertainties. To cope with a wide range of command signals, a robust adaptive fuzzy logic controller is proposed. The proposed controller adopts a dynamic inversion approach. Since feedback linearization is practically imperfect, robustifying and adaptive components are included in the control law to compensate for modeling errors and achieve acceptable tracking errors. Two fuzzy systems are implemented. The first system models the nominal values of the system’s nonlinearity. The second system is …

Go to article

Multi-Agents Architecture For Scheduling And Control Of Robotic Manufacturing Systems, Brahim Bouzouia Apr 2025

Multi-Agents Architecture For Scheduling And Control Of Robotic Manufacturing Systems, Brahim Bouzouia

Sultan Qaboos University Journal For Science

This paper presents an innovative Multi-Agent approach related to an advanced real time control of flexible manufacturing systems. The proposed architecture is based on the paradigm of Distributed Intelligence and Multi-Agent Systems. The developed Multi-Agent prototype system integrates the following functions: Scheduling, dispatching, monitoring and error handling. A new negotiation protocol for manufacturing systems is presented in this paper. The purpose of this protocol is to assign dynamic operations to the resources of the Manufacturing System in order to accomplish the proposed tasks. This protocol is able to deal with exceptions.

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

Deregulation Of Electricity Supply Industry In Oman, Hamed S. Al-Maghderi, Bruce Ramsay Apr 2025

Deregulation Of Electricity Supply Industry In Oman, Hamed S. Al-Maghderi, Bruce Ramsay

Sultan Qaboos University Journal For Science

This paper examines the opportunities available and the conditions needed for the deregulation of the Electricity Supply Industry (ESI), with particular reference to the Sultanate of Oman. The paper highlights the general issues of regulation required to encourage competition in the ESI. After that, the discussion focuses on regulation methods in the privatized ESI by describing the regulators control through price caps setting for regulatees, the conduct regulation process, the rate of return regulation setting, and the spot market (the pool) contract. Finally, the prospects of restructuring and privatizing the ESI in the Sultanate of Oman are examined by reviewing …

Go to article

Neural-Network-Based Fuzzy Logic Navigation Control For Intelligent Vehicles, Ahcene Farah, Amine Chohra Apr 2025

Neural-Network-Based Fuzzy Logic Navigation Control For Intelligent Vehicles, Ahcene Farah, Amine Chohra

Sultan Qaboos University Journal For Science

This paper proposes a Neural-Network-Based Fuzzy logic system for navigation control of intelligent vehicles. First, the use of Neural Networks and Fuzzy Logic to provide intelligent vehicles with more autonomy and intelligence is discussed. Second, the system for the obstacle avoidance behavior is developed. Fuzzy Logic improves Neural Networks (NN) obstacle avoidance approach by handling imprecision and rule-based approximate reasoning. This system must make the vehicle able, after supervised learning, to achieve two tasks: 1- to make one’s way towards its target by a NN, and 2- to avoid static or dynamic obstacles by a Fuzzy NN capturing the behavior …

Go to article

An Assessment Of Solid Waste And Landfilis In Muscat Area, Oman, Alaa El-Zawahry, Abulbasher M. Shahalam, Ramzi Taha, Turki Al-Busaidi Apr 2025

An Assessment Of Solid Waste And Landfilis In Muscat Area, Oman, Alaa El-Zawahry, Abulbasher M. Shahalam, Ramzi Taha, Turki Al-Busaidi

Sultan Qaboos University Journal For Science

The paper presents the results of a 1998 study of the solid waste generation within the greater Muscat City area. The recent data were compared with the available data from the last 10 years to assess the solid waste problems within the area. Five operating landfills were used as the data collection points. It appeared that through the last decade, the solid waste generation rate has increased sharply. However, the rate of waste production stabilized to 750 – 800 ton/day during the last three years of the 1990s. The rate amounts to 1.5 kg/person/day. Overall municipal waste volume decreased through …

Go to article

The Development Of A Database Management In Gis Applications In Oman, Osman Abdallah Osman Akif Apr 2025

The Development Of A Database Management In Gis Applications In Oman, Osman Abdallah Osman Akif

Sultan Qaboos University Journal For Science

The development of applying database management applications is currently underway within Geographical Information Systems (GIS) applications in the Sultanate of Oman.The establishment of a national database management system in Oman is considered as the backbone that is required within the Geographic Information System project in Oman. The principal of the GIS project in Oman was built upon unifying the used software packages over the sultanate which is ARC/INFO as GIS Package and ORACLE as database management software. These packages are used within the different participating Ministries in the GIS project in Oman.The participating ministries will handle information that are shared …

Go to article

Variation In Seedling Characteristics Of Five Populations Of Acacia Tortilis From The United Arab Emirates In Response To Increasing Sodium Chloride Concentrations, Fatma. M. Al-Ansari, Rashied. S. Modawi Apr 2025

Variation In Seedling Characteristics Of Five Populations Of Acacia Tortilis From The United Arab Emirates In Response To Increasing Sodium Chloride Concentrations, Fatma. M. Al-Ansari, Rashied. S. Modawi

Sultan Qaboos University Journal For Science

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 …

Go to article

Desert Nitrogen Cycles: Fecal Nitrogen From A Population Of The Sahelian Tree Locust In Oman, Michael D. Robinson Apr 2025

Desert Nitrogen Cycles: Fecal Nitrogen From A Population Of The Sahelian Tree Locust In Oman, Michael D. Robinson

Sultan Qaboos University Journal For Science

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 …

Go to article

Influence Of Aging Conditions On Fatigue Fracture Behaviour Of 6063 Aluminum Alloy, Rafiq Ahmed Siddiqui, Saeed Ali Al-Araimi, Ahmet Turgutlu Apr 2025

Influence Of Aging Conditions On Fatigue Fracture Behaviour Of 6063 Aluminum Alloy, Rafiq Ahmed Siddiqui, Saeed Ali Al-Araimi, Ahmet Turgutlu

Sultan Qaboos University Journal For Science

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 …

Go to article

Determination Of Sugar And Mineral Contents In Some Omani Fruits, Salma M. Z.Al-Kindy, Abdulrahman O. Abdulnour, Maryam M. Al-Rasbi Apr 2025

Determination Of Sugar And Mineral Contents In Some Omani Fruits, Salma M. Z.Al-Kindy, Abdulrahman O. Abdulnour, Maryam M. Al-Rasbi

Sultan Qaboos University Journal For Science

Omani fruits were analyzed for their reducing sugar, total sugar contents and some minerals. Among the minerals studied were Ca, Mg, Na, K and P. The amounts of total sugar and reducing sugar were within the range of values reported in the literature for the analysis of fruits conducted elsewhere. The amounts of the minerals differ from the reported literature values. This may be attributed to soil composition, climate and type of cultivar.

Go to article

First Prev Next Last