An experimental investigation of damage detection of CFRP using an electrical resistance change method

This study investigated damage detection, location, and quantification in carbon fibre composite laminate structures

Q-learning based distributed denial of service detection

Distributed denial of service (DDoS) attacks the target service providers by sending a huge amount of traffic to prevent legitimate users from getting the service. These attacks become more challenging in the software-defined network paradigm, due to the separation of the control plane from the data plane. Centralized software defined networks are more vulnerable to DDoS attacks that may cause the failure of all networks. In this work, a new approach is proposed based on q-learning to enhance the detection of DDoS attacks and reduce false positives and false negatives. The results of this work are compared with entropy detection in terms of the number of received packets to detect the attack and also the continuity of service for legitimate users. Moreover, these results indicate that the proposed system detects the DDoS attack from flash crowds and redirects the traffic to the edge of the data center. A second controller is used to redirect traffic to a honeypot server that works as a mirror server. This guarantees the continuity of service for both normal and suspected traffic until further analysis is done. The results indicate an increase of up to 50% in the throughput compared to other approaches

Semantic reasoning in cognitive networks for heterogeneous wireless mesh systems

The next generation of wireless networks is expected to provide not only higher bandwidths anywhere and at any time but also ubiquitous communication using different network types. However, several important issues including routing, self-configuration, device management, and context awareness have to be considered before this vision becomes reality. This paper proposes a novel cognitive network framework for heterogeneous wireless mesh systems to abstract the network control system from the infrastructure by introducing a layer that separates the management of different radio access networks from the data transmission. This approach simplifies the process of managing and optimizing the networks by using extendable smart middleware that automatically manages, configures, and optimizes the network performance. The proposed cognitive network framework, called FuzzOnto, is based on a novel approach that employs ontologies and fuzzy reasoning to facilitate the dynamic addition of new network types to the heterogeneous network. The novelty is in using semantic reasoning with cross-layer parameters from heterogeneous network architectures to manage and optimize the performance of the networks. The concept is demonstrated through the use of three network architectures: 1) wireless mesh network; 2) long-term evolution (LTE) cellular network; and 3) vehicular ad hoc network (VANET). These networks utilize nonoverlapped frequency bands and can operate simultaneously with no interference. The proposed heterogeneous network was evaluated using ns-3 network simulation software. The simulation results were compared with those produced by other networks that utilize multiple transmission devices. The results showed that the heterogeneous network outperformed the benchmark networks in both urban and VANET scenarios by up to 70% of the network throughput, even when the LTE network utilized a high bandwidth

Cognitive network framework for heterogeneous wireless mesh systems

Heterogeneous wireless mesh networks (WMN) provide an opportunity to secure higher network capacity, wider coverage and higher quality of service (QoS). However, heterogeneous systems are complex to configure because of the high diversity of associated devices and resources. This thesis introduces a novel cognitive network framework that allows the integration of WMNs with long-term evolution (LTE) networks so that none of the overlapped frequency bands are used. The framework consists of three novel systems: the QoS metrics management system, the heterogeneous network management system and the routing decision-making system. The novelty of the QoS metrics management system is that it introduces a new routing metric for multi-hop wireless networks by developing a new rate adaptation algorithm. This system directly addresses the interference between neighbouring nodes, which has not been addressed in previous research on rate adaptation for WMN. The results indicated that there was a significant improvement in the system throughput by as much as to 90%. The routing decision-making system introduces two novel methods to select the transmission technology in heterogeneous nodes: the cognitive heterogeneous routing (CHR) system and the semantic reasoning system. The CHR method is used to develop a novel reinforcement learning algorithm to optimise the selection of transmission technology on wireless heterogeneous nodes by learning from previous actions. The semantic reasoning method uses ontologies and fuzzy-based semantic reasoning to facilitate the dynamic addition of new network types to the heterogeneous network. The simulation results showed that the heterogeneous network outperformed the benchmark networks by up to 200% of the network throughput

Maxillary Artery Pseudoaneurysm as a Complication of Maxillofacial Injuries: Report of three cases and literature review

Traumatic maxillary artery pseudoaneurysm is an uncommonly reported complication in the field of oral and maxillofacial surgery. It is usually discovered incidentally, either early after trauma or weeks-to-months later. Quick recognition and prompt management are essential to avoid devastating consequences. In this paper, we report three uncommon cases of maxillary artery pseudoaneurysm recognised during the surgical management of maxillofacial injuries in Muscat, Oman. All cases presented as sudden brisk bleeding during the intraoperative surgical repair and were subsequently diagnosed and successfully managed by endovascular embolisation with platinum coils. This case report highlights the clinical presentation, diagnosis and management of maxillary artery pseudoaneurysm, in addition to a brief review of the literature.Keywords: Maxillofacial Injuries; Maxillary Artery; Pseudoaneurysm; Mandibular Condyle; Angiography; Therapeutic Embolization; Case Report; Oman

Analysis of Novel Techniques of Drag Reduction and Stability Increase for Sport Utility Vehicles using Computational Fluid Dynamics

The main objective of this study is to investigate ways to reduce the aerodynamic drag coefficient and to increase the stability of road vehicles using three-dimensional Computational Fluid Dynamics (CFD) simulation. Two baseline models, the Ahmed body and the Land Rover Discovery 4, were used in these simulations. The effects of model scale and slant angle were investigated for the Ahmed body in addition to a new technique to measure the drag coefficient used in the experiments has been investigated numerically in this study. Many new aerodynamic devices and external design modifications were used for the Land Rover Discovery 4. ANSYS Meshing was used to create a variety of mesh cases for mesh optimization and ANSYS Fluent software was used to simulate all models. Different sizes of computational domain were used in order to study the effect of the blockage ratio on the aerodynamic behaviour. The range of Reynolds numbers used in this study for the Ahmed body was between 3 × 105 and 30 × 105 similar to the experimental studies. The uniform free stream velocity of air at the inlet ranging from 100km/h to 140km/h was used for the Land Rover Discovery 4. Reynolds-averaged Navier–Stokes equations (RANS) and Large Eddy Simulation (LES) turbulence models were used to establish the most appropriate turbulence model for the Ahmed body geometry. Only RANS was used for the Land Rover Discovery 4. In general, the trend of drag coefficient as a function of the Reynolds number for the Ahmed body was in good agreement with the experiments, whereas LES simulation results were closer to the experimental data. The drag and lift coefficients obtained from ANSYS Fluent for the baseline of the Land Rover Discovery 4 were validated with experimental data. It is found that the use of modern aerodynamic add-on devices and modifications has a significant effect in reducing the aerodynamic drag coefficient

Effect of Fuel on the Structural and Optical Properties of MgO Nanoparticles Prepared by Auto–Combustion of Sol-Gel Method

Magnesium nitrate as precursor and citric acid as fuel are used as a starting material for the preparation  magnesium oxide (MgO) nanoparticles via sol- gel of auto–combustion  method.  X-ray diffraction patterns indicate that the obtain (MgO) nanoparticles are in good crystallinity and show that the all grain size was decreases with increasing of concentration citric acid as fuel. The crystallite size was calculated using Scherrer and Williamson-Hall formula at difference ratios of fuel which have maximum crystallite size (13.55 nm) and  (14.26 nm) respectively. The SEM images for MgO powder prepared with fuel (Citric acid) at three various molar ratios show the morphology of the oxides is mostly spherical with some agglomeration. The optical properties  show that  the transmittance decrease with increase the fuel amount and  additives ammonia and fuel played an important role in the combustion. Keywords: MgO , Nanoparticles , Sol-Gel, Auto–Combustion, Structural , Optica

Temporomandibular Joint Ankylosis as a Complication of Neonatal Septic Arthritis : Report of two cases

Temporomandibular joint (TMJ) ankylosis as a complication of neonatal septic arthritis is rarely reported in the literature. We report two clinical cases of unilateral TMJ ankylosis occurring in paediatric patients subsequent to neonatal septic arthritis. The first case was a 15-month-old male infant who presented to the Sultan Qaboos University Hospital, Muscat, Oman, in May 2010. According to the published English scientific literature, he is the youngest person yet to be diagnosed with this condition. The second case was a five-year-old female who presented to the Al-Nahda Hospital, Muscat, Oman, in October 2011. Both cases presented with facial asymmetry and trismus. They subsequently underwent gap arthroplasty and interpositional temporalis muscle and fascia grafts which resulted in an immediate improvement in mouth opening. Postoperatively, the patients underwent active jaw physiotherapy which was initially successful. Both patients were followed up for a minimum of two years following their surgeries