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Search Results: 1 - 10 of 685913 matches for " S. A. Al-Ameen "
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Some biochemical effects of Aloe vera leaves on tissues in normal mice
M. G. Matti,S. A. Al-Ameen,S. H. Rashed
Iraqi Journal of Veterinary Sciences , 2010,
Abstract: This research was carried out mainly to investigate the effects of the aqueous extract and proteinous fractions of Aloe veraleaves on cholesterol, acetycholinesterase in brain, glycogen, glutathione in liver and malonaldehyde levels in heart in normalmale albino mice. The antioxidant properties and inhibition of acetylcholine-sterase in tissue were detected. Intraperitonealadministration of Aloe vera extract in concentration of 400 mg/kg significantly decreased the levels of AchE in brain by (-88.27%) and glutathione content in liver by (-35.48%), and increased the levels of glycogen in liver and malonaldehyde inheart by (22.60%, 85.50%) respectively. At a concentration of 300 mg/kg Aloe vera extract significantly increased the level ofcholesterol in brain by (24.39%). These results clearly show the antioxidant property of the extract of Aloe vera leaves.
Scattering theory with a natural regularization: Rediscovering the J-matrix method
A. D. Alhaidari,H. Bahlouli,M. S. Abdelmonem,F. S. Al-Ameen,T. H. Al-Abdulaal
Physics , 2006, DOI: 10.1016/j.physleta.2006.12.027
Abstract: In three dimensional scattering, the energy continuum wavefunction is obtained by utilizing two independent solutions of the reference wave equation. One of them is typically singular (usually, near the origin of configuration space). Both are asymptotically regular and sinusoidal with a phase difference (shift) that contains information about the scattering potential. Therefore, both solutions are essential for scattering calculations. Various regularization techniques were developed to handle the singular solution leading to different well-established scattering methods. To simplify the calculation the regularized solutions are usually constructed in a space that diagonalizes the reference Hamiltonian. In this work, we start by proposing solutions that are already regular. We write them as infinite series of square integrable basis functions that are compatible with the domain of the reference Hamiltonian. However, we relax the diagonal constraint on the representation by requiring that the basis supports an infinite tridiagonal matrix representation of the wave operator. The hope is that by relaxing this constraint on the solution space a larger freedom is achieved in regularization such that a natural choice emerges as a result. We find that one of the resulting two independent wavefunctions is, in fact, the regular solution of the reference problem. The other is uniquely regularized in the sense that it solves the reference wave equation only outside a dense region covering the singularity in configuration space. However, asymptotically it is identical to the irregular solution. We show that this natural and special regularization is equivalent to that already used in the J-matrix method of scattering.
Volterra-Fredholm Integral Equation with Carleman Kernel in Position and Time
A.K. Khamis,M.A. Al-Ameen
Journal of Engineering and Applied Sciences , 2012,
Abstract: In this study, we introduce an efficient method to find and discuss an approximate solution of the integral equation of type Volterra-Fredholm in the space L2[a, b] x [0, T]. The kernel of Fredholm is considered in position and represented in a logarithmic form, while the kernel of Volterra is taken in time as a continuous function. Using a numerical method we obtain a linear system of Fredholm integral equations is position which will be solved.
Q-A: Towards the Solution of Usability-Security Tension in User Authentication
Mahdi Nasrullah Al-Ameen,S M Taiabul Haque,Matthew Wright
Computer Science , 2014,
Abstract: Users often choose passwords that are easy to remember but also easy to guess by attackers. Recent studies have revealed the vulnerability of textual passwords to shoulder surfing and keystroke loggers. It remains a critical challenge in password research to develop an authentication scheme that addresses these security issues, in addition to offering good memorability. Motivated by psychology research on humans' cognitive strengths and weaknesses, we explore the potential of cognitive questions as a way to address the major challenges in user authentication. We design, implement, and evaluate Q-A, a novel cognitive-question-based password system that requires a user to enter the letter at a given position in her answer for each of six personal questions (e.g. "What is the name of your favorite childhood teacher?"). In this scheme, the user does not need to memorize new, artificial information as her authentication secret. Our scheme offers 28 bits of theoretical password space, which has been found sufficient to prevent online brute-force attacks. Q-A is also robust against shoulder surfing and keystroke loggers. We conducted a multi-session in-lab user study to evaluate the usability of Q-A; 100% of users were able to remember their Q-A password over the span of one week, although login times were high. We compared our scheme with random six character passwords and found that login success rate in Q-A was significantly higher. Based on our results, we suggest that Q-A would be most appropriate in contexts that demand high security and where logins occur infrequently (e.g., online bank accounts).
Design of a High Accurate Aircraft Ground-based Landing System
Ahmad Abbas Al-Ameen Salih1,a and Amzari Zhahir
International Journal of Engineering Trends and Technology , 2013,
Abstract: The rapid increase in aviation industry requires parallel effective plans, programs and designs of systems and facilities nationwide to fulfill the increasing needs for safe air transportation. Aircraft landing remains a problem for a long time all over the world. Systems that aircraft rely on in landing are unreliable to perform a precise guidance due to many limitations such as inaccuracy, unreliability and dependency. In low visibility conditions, when pilots are unable to see the runway, the aircrafts are diverted to another airport. However, low visibility can also affect all airports in the vicinity, forcing aircrafts to land in low visibility conditions depending on Instrument Flight Rules (IFR). Aircraft approach and landing are the most hazardous portions of flight; accidents records indicate that approximately 50 percent of the accidents occur during aircraft landing. Aircraft landing Category III C is not yet in operation anywhere in the world. It requires landing with no visibility or runway visual range.Currently, Global Positioning System (GPS) is the main navigation system used all over the world for aircraft navigation, approach and landing. However, in aircraft approach and landing phase, the accuracy of GPS is not sufficient to perform a perfect landing due to the possibility of aircraft to be drifted out of the runway. The accuracy of GPS could be improved to 3 meter by sending correction. Improved accuracy has not been able to meet ICAO standards for aircraft automatic landing. In this paper, aircraft landing systems characteristics, performance and accuracies have been studied and compared for the purpose of assessinglimitations and drawbacks. An aircraft landing system with improved performance is proposed to meet ICAO standards for all-weather aircraft landing required and recommended practices with high accuracy to perform full automatic landing for aircrafts
An Intelligent Fire Alert System using Wireless Mobile Communication
Mahdi Nasrullah Al-Ameen
Computer Science , 2013,
Abstract: The system has come to light through the way of inspiration to develop a compact system, based on the fundamental ideas of safety, security and control. Once this system is installed to operation specifying temperature and smoke threshold, in case of any emergency situation due to increasing temperature and/or smoke at place surpassing the threshold, the system immediately sends automatic alert-notifications to the users, concerned with the situations. The user gets total control over the system through mobile SMS, even from the distant location, that to change the threshold, turn on/off the feature of sending 'alert notification' and also to reset the system after the emergency situation is overcome. Before executing any command (through SMS) from the user, the system asks for the preset password to verify an authorized user. The security issues have been considered with utter attention in this system to ensure its applicability in industries and business organizations, where security is an important concern. Hence, the fundamental ideas of safety, security and control have been entirely ensured through the system, which have definitely worked as the gear moving factor to look for a new dimension of an 'Intelligent Fire Alert System'.
A Comprehensive Study of the GeoPass User Authentication Scheme
Mahdi Nasrullah Al-Ameen,Matthew Wright
Computer Science , 2014,
Abstract: Before deploying a new user authentication scheme, it is critical to subject the scheme to comprehensive study. Few works, however, have undertaken such a study. Recently, Thorpe et al. proposed GeoPass, the most promising of a class of user authentication schemes based on geographic locations in online maps. Their study showed very high memorability (97%) and satisfactory resilience against online guessing, which means that GeoPass has compelling features for real-world use. No comprehensive study, however, has been conducted for GeoPass or any other location-based password scheme. In this paper, we present a systematic approach for the detailed evaluation of a password system, which we implement to study GeoPass. We conducted three separate studies to evaluate the suitability of GeoPass for widespread use. First, we performed a field study over two months, in which users in a real-world setting remembered their location-passwords 96% of the time and showed improvement with more login sessions. Second, we conducted a study to test how users would fare with multiple location-passwords and found that users remembered their location-passwords in less than 70% of login sessions, with 40% of login failures due to interference effects. Third, we conducted a study to examine the resilience of GeoPass against shoulder surfing. Our participants played the role of attackers and had an overall success rate of 48%. Based on our results, we suggest suitable applications of GeoPass in its current state and identify aspects of GeoPass that must be improved before widespread deployment could be considered.
iPersea : The Improved Persea with Sybil Detection Mechanism
Mahdi Nasrullah Al-Ameen,Matthew Wright
Computer Science , 2014,
Abstract: P2P systems are highly susceptible to Sybil attacks, in which an attacker creates a large number of identities and uses them to control a substantial fraction of the system. Persea is the most recent approach towards designing a social network based Sybil-resistant DHT. Unlike prior Sybil-resistant P2P systems based on social networks, Persea does not rely on two key assumptions: (i) that the social network is fast mixing, and (ii) that there is a small ratio of attack edges to honest peers. Both assumptions have been shown to be unreliable in real social networks. The hierarchical distribution of node IDs in Persea confines a large attacker botnet to a considerably smaller region of the ID space than in a normal P2P system and its replication mechanism lets a peer to retrieve the desired results even if a given region is occupied by attackers. However, Persea system suffers from certain limitations, since it cannot handle the scenario, where the malicious target returns an incorrect result instead of just ignoring the lookup request. In this paper, we address this major limitation of Persea through a Sybil detection mechanism built on top of Persea system, which accommodates inspection lookup, a specially designed lookup scheme to detect the Sybil nodes based on their responses to the lookup query. We design a scheme to filter those detected Sybils to ensure the participation of honest nodes on the lookup path during regular DHT lookup. Since the malicious nodes are opt-out from the lookup path in our system, they cannot return any incorrect result during regular lookup. We evaluate our system in simulations with social network datasets and the results show that catster, the largest network in our simulation with 149700 nodes and 5449275 edges, gains 100% lookup success rate, even when the number of attack edges is equal to the number of benign peers in the network.
Towards Making Random Passwords Memorable: Leveraging Users' Cognitive Ability Through Multiple Cues
Mahdi Nasrullah Al-Ameen,Matthew Wright,Shannon Scielzo
Computer Science , 2015,
Abstract: Given the choice, users produce passwords reflecting common strategies and patterns that ease recall but offer uncertain and often weak security. System-assigned passwords provide measurable security but suffer from poor memorability. To address this usability-security tension, we argue that systems should assign random passwords but also help with memorization and recall. We investigate the feasibility of this approach with CuedR, a novel cued-recognition authentication scheme that provides users with multiple cues (visual, verbal, and spatial) and lets them choose the cues that best fit their learning process for later recognition of system-assigned keywords. In our lab study, all 37 of our participants could log in within three attempts one week after registration (mean login time: 38.0 seconds). A pilot study on using multiple CuedR passwords also showed 100% recall within three attempts. Based on our results, we suggest appropriate applications for CuedR, such as financial and e-commerce accounts.
ReDS: A Framework for Reputation-Enhanced DHTs
Ruj Akavipat,Mahdi N. Al-Ameen,Apu Kapadia,Zahid Rahman,Roman Schlegel,Matthew Wright
Computer Science , 2012, DOI: 10.1109/TPDS.2013.231
Abstract: Distributed Hash Tables (DHTs) such as Chord and Kademlia offer an efficient solution for locating resources in peer-to-peer networks. Unfortunately, malicious nodes along a lookup path can easily subvert such queries. Several systems, including Halo (based on Chord) and Kad (based on Kademlia), mitigate such attacks by using a combination of redundancy and diversity in the paths taken by redundant lookup queries. Much greater assurance can be provided, however. We describe Reputation for Directory Services (ReDS), a framework for enhancing lookups in redundant DHTs by tracking how well other nodes service lookup requests. We describe how the ReDS technique can be applied to virtually any redundant DHT including Halo and Kad. We also study the collaborative identification and removal of bad lookup paths in a way that does not rely on the sharing of reputation scores --- we show that such sharing is vulnerable to attacks that make it unsuitable for most applications of ReDS. Through extensive simulations we demonstrate that ReDS improves lookup success rates for Halo and Kad by 80% or more over a wide range of conditions, even against strategic attackers attempting to game their reputation scores and in the presence of node churn.
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