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Search Results: 1 - 10 of 2413 matches for " Khalid Murad "
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Distributed Adaptive Scheduling for Finite Horizon in Wireless Ad hoc Networks
Murad Khalid,Yufeng Wang,Xuan Hung Le,In-ho Ra
Journal of Communications , 2012, DOI: 10.4304/jcm.7.2.155-164
Abstract: A cooperative ratio-based scheduling scheme with minimal signaling that enhances network throughput and fairness in a wireless ad hoc network is presented in this paper. Throughput maximization problem under fairness constraint in a finite horizon is formulated as a novel multi-window optimization problem. Through analysis users' thresholds are shown to be time variant for throughput maximization with fairness in each time window. Simulation results clearly show that compared with non decision-based strategy, simple ratio-based scheme (SR) achieves within 1.6% of the global optimal value in terms of throughput and is scalable in terms of the number of nodes. Fairness index performance is marginally better than non decision-based strategy. Next, we show throughput degradation of SR scheme for asymmetric channels, and introduce general ratio-based scheme (GR) that adapts to provide higher throughput than fairness in a fully distributed manner for asymmetric channel conditions.
An Efficient Mutual Authentication and Access Control Scheme for Wireless Sensor Networks in Healthcare
Xuan Hung Le,Murad Khalid,Ravi Sankar,Sungyoung Lee
Journal of Networks , 2011, DOI: 10.4304/jnw.6.3.355-364
Abstract: Wireless sensor networks (WSNs) will play an active role in the 21th Century Healthcare IT to reduce the healthcare cost and improve the quality of care. The protection of data confidentiality and patient privacy are the most critical requirements for the ubiquitous use of WSNs in healthcare environments. This requires a secure and lightweight user authentication and access control. Symmetric key - based access control is not suitable for WSNs in healthcare due to dynamic network topology, mobility, and stringent resource constraints. In this paper, we propose a secure, lightweight public key - based security scheme, Mutual Authentication and Access Control based on Elliptic curve cryptography (MAACE). MAACE is a mutual authentication protocol where a healthcare professional can authenticate to an accessed node (a PDA or medical sensor) and vice versa. This is to ensure that medical data is not exposed to an unauthorized person. On the other hand, it ensures that medical data sent to healthcare professionals did not originate from a malicious node. MAACE is more scalable and requires less memory compared to symmetric key-based schemes. Furthermore, it is much more lightweight than other public key-based schemes. Security analysis and performance evaluation results are presented and compared to existing schemes to show advantages of the proposed scheme.
Coherence time-based cooperative MAC protocol 1 for wireless ad hoc networks
Khalid Murad,Wang Yufeng,Butun Ismail,Kim Hyung-jin
EURASIP Journal on Wireless Communications and Networking , 2011,
Abstract: In this article, we address the goal of achieving performance gains under heavy-load and fast fading conditions. CoopMACI protocol proposed in Proceedings of the IEEE International Conference on Communications (ICC), Seoul, Korea, picks either direct path or relay path based on rate comparison to enhance average throughput and delay performances. However, CoopMACI performance deteriorates under fading conditions because of lower direct path or relay path reliability compared to UtdMAC (Agarwal et al. LNCS, 4479, 415-426, 2007). UtdMAC was shown to perform better than CoopMACI in terms of average throughput and delay performances because of improved transmission reliability provided by the backup relay path. Although better than CoopMACI, UtdMAC does not fully benefit from higher throughput relay path (compared to the direct path), since it uses relay path only as a secondary backup path. In this article, we develop a cooperative MAC protocol (termed as instantaneous relay-based cooperative MAC--IrcMAC) that uses channel coherence time and estimates signal-to-noise ratio (SNR) of source-to-relay, relay-to-destination, and source-to-destination links, to reliably choose between relay path or direct path for enhanced throughput and delay performances. Unique handshaking is used to estimate SNR and single bit feedbacks resolve contentions among relay nodes, which further provides source node with rate (based on SNR) information on source-to-destination, source-to-relay, and relay-to-destination links. Simulation results clearly show that IrcMAC significantly outperforms the existing CoopMACI and the UtdMAC protocols in wireless ad hoc network. Results show average throughput improvements of 41% and 64% and average delay improvementd of 98.5% and 99.7% compared with UtdMAC and CoopMACI, respectively.
The foundation of the theory of the universe dark energy and its nature  [PDF]
Murad Shibli
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.33023
Abstract: Surprisingly recent astronomical observations have provided strong evidence that our universe is not only expanding, but also is expanding at an accelerating rate. This paper pre- sents a basis of the theory of universe space- time dark energy, a solution of Einstein’s cosmological constant problem, physical interpretation of universe dark energy and Einstein’s cosmological constant Lambda and its value ( = 0.29447 × 10-52 m-2), values of universe dark energy density 1.2622 × 10-26 kg/m3 = 6.8023 GeV, universe critical density 1.8069 × 10-26 kg/m3 = 9.7378 GeV, universe matter density 0.54207 × 10-26 kg/m3 = 2.9213 GeV, and universe radiation density 2.7103 × 10-31 kg/m3 = 1.455 MeV. The interpretation in this paper is based on geometric modeling of space-time as a perfect four- dimensional continuum cosmic fluid and the momentum generated by the time. In this modeling time is considered as a mechanical variable along with other variables and treated on an equal footing. In such a modeling, time is considered to have a mechanical nature so that the momentum associated with it is equal to the negative of the universe total energy. Since the momentum associated with the time as a mechanical variable is equal to the negative system total energy, the coupling in the time and its momentum leads to maximum increase in the space-time field with 70.7% of the total energy. Moreover, a null paraboloid is obtained and interpreted as a function of the momentum generated by time. This paper presents also an interpretation of space-time tri-dipoles, gravity field waves, and gravity carriers (the gravitons). This model suggests that the space-time has a polarity and is composed of dipoles which are responsible for forming the orbits and storing the space-time energy-momentum. The tri-di- poles can be unified into a solo space-time dipole with an angle of 45 degrees. Such a result shows that the space-time is not void, on the contrary, it is full of conserved and dynamic energy-momentum structure. Furthermore, the gravity field waves is modeled and assumed to be carried by the gravitons which move in the speed of light. The equivalent mass of the graviton (rest mass) is found to be equal to 0.707 of the equivalent mass of the light photons. Such a result indicates that the lightest particle (up to the author’s knowledge) in the nature is the graviton and has an equivalent mass equals to 2.5119 x 10-52 kg. Based on the fluidic nature of dark energy, a fourth law of thermodynamics is proposed and a new physical interpretation of Kepler’s Laws are presented. Additionally,
In Vivo Dynamic Image Characterization of Brain Tumor Growth Using Singular Value Decomposition and Eigenvalues  [PDF]
Murad Shibli
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.43026
Abstract: This paper presents a dynamic image approach to characterize the growth of brain cancer invasion of tumor gliomas cells using singular value decomposi-tion (SVD) technique. Such a dynamic image is identi-fied by the white and grey matter displayed by mag-netic resonance (MR) images of the patient brain taken at different times. SVD components and prop-erties have been analyzed for different brain images. It is figured out that the growth of tumor cells is quantized by the SVD eigenvalues. Since SVD geo-metrically interprets an ellipsoid transformation, then the higher the eigenvalues, the more of tumor growth is. In vivo SVD dynamic imaging offers a more pre-dictive model to assess the tumor therapy than con-ventional technologies. Furthermore, an efficient dy-namic white-black indicator of the tumor growth rate is constructed based on the change in the diagonal eigenvalues matrices of two MR images taken at dif-ferent times. Finally, SVD image processing results are demonstrated to verify the effectiveness of the applied approach that can be implemented for each individual patient.
Unified Modeling Approach of Kinematics, Dynamics and Control of a Free-Flying Space Robot Interacting with a Target Satellite  [PDF]
Murad Shibli
Intelligent Control and Automation (ICA) , 2011, DOI: 10.4236/ica.2011.21002
Abstract: In this paper a unified control-oriented modeling approach is proposed to deal with the kinematics, linear and angular momentum, contact constraints and dynamics of a free-flying space robot interacting with a target satellite. This developed approach combines the dynamics of both systems in one structure along with holonomic and nonholonomic constraints in a single framework. Furthermore, this modeling allows consid-ering the generalized contact forces between the space robot end-effecter and the target satellite as internal forces rather than external forces. As a result of this approach, linear and angular momentum will form holonomic and nonholonomic constraints, respectively. Meanwhile, restricting the motion of the space robot end-effector on the surface of the target satellite will impose geometric constraints. The proposed momentum of the combined system under consideration is a generalization of the momentum model of a free-flying space robot. Based on this unified model, three reduced models are developed. The first reduced dynamics can be considered as a generalization of a free-flying robot without contact with a target satellite. In this re-duced model it is found that the Jacobian and inertia matrices can be considered as an extension of those of a free-flying space robot. Since control of the base attitude rather than its translation is preferred in certain cases, a second reduced model is obtained by eliminating the base linear motion dynamics. For the purpose of the controller development, a third reduced-order dynamical model is then obtained by finding a common solution of all constraints using the concept of orthogonal projection matrices. The objective of this approach is to design a controller to track motion trajectory while regulating the force interaction between the space robot and the target satellite. Many space missions can benefit from such a modeling system, for example, autonomous docking of satellites, rescuing satellites, and satellite servicing, where it is vital to limit the con-tact force during the robotic operation. Moreover, Inverse dynamics and adaptive inverse dynamics control-lers are designed to achieve the control objectives. Both controllers are found to be effective to meet the specifications and to overcome the un-actuation of the target satellite. Finally, simulation is demonstrated by to verify the analytical results.
Dynamics and Controllability of Financial Derivatives: Towards Stabilization the Global Financial Systems Crisis  [PDF]
Murad Shibli
Journal of Mathematical Finance (JMF) , 2012, DOI: 10.4236/jmf.2012.21007
Abstract: This paper presents a new dynamic approach to control and stabilize the global financial derivatives. Since 2007 the Global Financial Economy has been experiencing what is said to be the worst financial crisis since the Great Depression in the 1930’s. The Bank of International Settlements (BIS) in Switzerland has recently reported that global outstanding derivatives have reached 1.14 quadrillion dollars: $548 Trillion in listed credit derivatives plus $596 trillion in notional OTC derivatives. Although the financial derivatives are governed by the celebrated parabolic partial differential Black- Scholes formula, but it is not clear how derivatives are controlled and stabilized. This paper investigates equilibrium, stability and control of financial derivatives. The analysis is based on the discretization of Balck-Scholes formula to a system of linear ordinary differential equations. It is found that such financial derivatives experience a drift which hardly can be brought to equilibrium state. Controllability and observability conditions of financial systems are proposed. Moreover, stability of such derivatives is tested by the virtue of Liapunov methodology. It is figured out that financial system should satisfy the quadratic form which can be interpreted as a conservation condition of financial instruments. Furthermore, a financial state-feedback control system is proposed. Such analysis shows that the financial derivatives system needs to be injected with cash to maintain its stability. These results may explain the shortfall of li-quidity needed to substitute for the 1.14 quadrillion dollars bubble. Finally, examples and simulation results are demonstrated to verify the effectiveness of the proposed approach.
The Fundamental Principle of Conservation of Physical Money: Its Violation and the GlobalFinancial System Collapse  [PDF]
Murad Al-Shibli
iBusiness (IB) , 2011, DOI: 10.4236/ib.2011.31013
Abstract: Over the last two years the world has witnessed a financial tsunami that rocked the global financial systems. This paper presents the fundamental principle of conservation of physical money of the global financial system that guarantees its equilibrium and stability. Similar to the principle of conservation of mass-energy systems and based on the commodity money concept, then the physical money cannot be created from nullity nor can be destroyed. As a result, violation of such a system will lead to a deficit in the financial system which cannot be paid off. Additionally, violation of gold standard and the breakage of the Bretton Woods system are the reason behind the current world financial crisis. Paying non-zero interest on money loans will violate this principle as well. The international banking system is volatile and over-valued since it is based on the fractional banking technique that banks do not actually need to have the money to back up the deposits their clients have made into their accounts. Instead, the banks are required only to keep a small fraction of such deposits on hand. The world Today’s reserves wealth of Gold, Silver and Copper is estimated by 8.63 Trillion US$ compared to 4.3 Trillion US$ in Currencies. Moreover The Bank of International Settlements (BIS) in Switzerland has recently reported that global outstanding derivatives have reached 1.14 quadrillion dollars: $548 Trillion in listed credit derivatives plus $596 trillion in notional OTC derivatives. Furthermore, by 2007 credit default swap total value has dramatically increased to an estimated $45 trillion to $62 trillion. Subprime mortgage crisis, credit crisis and banking closure all have resulted from the violation of conservation money. Taking into the account that the World's GDPs for all nations is approximately $50 trillion and all of the asset value of the world is only $190 Trillion, it can be seen easily that the over-valued $1140 trillion financial derivatives will lead in the near future to the collapse of the international financial system similar to Iceland, Greece, Ireland crises and potentially in Spain, Portugal, and Italy.
An Overview of Conventional and Non-Conventional Water Resources in Arid Region: Assessment and Constrains of the United Arab Emirates (UAE)  [PDF]
Ahmed A. Murad
Journal of Water Resource and Protection (JWARP) , 2010, DOI: 10.4236/jwarp.2010.22020
Abstract: The aridity, population growth, agriculture and industrial activities threaten the water resources in the United Arab Emirates (UAE). In UAE, groundwater quantity is reduced and its quality is also deteriorated due to the scanty of rainfall and over pumping for different uses. The deficit of groundwater is met by desalinated water and reused of treated wastewater. Agricultural activities have negative impacts on water resources and this causes reduction of groundwater quality as the agriculture the main land use in the UAE and it accounts for more than 70% of groundwater use. The treated wastewater is an alternative source for agricultural activities. To improve the current water situation, a national water resources strategy has been prepared and imple-mented to assist in achieve this target and maintain the country’s water security. This paper intends to give an overview of water resources in the UAE with emphasis on challenges facing the management of these resources.
The basic blocks of the universe matter: Boltzmann fundamental particle and energy quanta of dark matter and dark energy  [PDF]
Murad Shibli, Sohail Anwar
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.39099
Abstract: Recent astronomical NASA observations indicates that visible matter contributes only to about 4% of the universe total energy density, meanwhile, dark matter and dark energy contributes to 26% and 70% of the universe total energy, respectively, with an average density close to 10–26 kg/m3. This paper proposes an equation of state of dark energy and dark matter as one unified entity. This equation is derived based on the ideal gas equation, Boltzmann constant, Einstein energy-mass principle and based on the assumption that dark energy and dark matter behave as a perfect fluid. This analysis presents what could be the most fundamental particle and quanta of dark matter and dark energy. Considering NASA’s Cosmic Microwave Background Explorer (CMB) which estimated that the sky has an average temperature close to 2.7251 Kelvin, then the equivalent mass and energy of the proposed fundamental particle is determined. It is found that this candidate particle has an equivalent mass of 4.2141 × 10–40 Kg which is equivalent to 3.7674 × 10–23 J. Surprisingly, this value has the same order of Boltzmann constant KB = 1.38 ×10–23 J/K. This candidate particle could be the most fundamental and lightest particle in Nature and serves as the basic block of matter (quarks and gluons). Moreover, assuming a uniform space dark energy/dark matter density, then the critical temperature at which the dark matter has a unity entity per volume is determined as 34.983 × 1012 K. Analytically, it proposes that at this trillion temperature scale, the dark matter particles unified into a new quark-hydron particle. Finally, tentative experimental verification can be con ducted using the Relativistic Heavy Ion Collider (RHIC).
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