An Improved Model for the Dynamic Routing Effect Algorithm for Mobility Protocol

An ad-hoc network is a packet radio network in which individual mobile nodes perform routing functions. Typically, an ad-hoc networking concept allows users wanting to communicate with each other while forming a temporary network, without any form of centralized administration. Each node participating in the network performs both the host and router function, and willing to forward packets for other nodes. For this purpose a routing protocol is needed. A novel approach utilizes the uniqueness of such a network i. e. distance, location and speed of the nodes, introducing a Distance Routing Effect Algorithm for Mobility (DREAM). The protocol uses the distance effect and the mobility rate as a means to assure routing accuracy. When data needs to be exchanged between two nodes, the directional algorithm sends messages in the recorded direction of the destination node, guaranteeing the delivery by following the direction. The improved algorithm suggested within this thesis project includes an additional parameter, direction of travel, as a means of determining the location of a destination node. When data needs to be exchanged between two nodes, the directional algorithm sends messages in the recorded direction of the destination node, guaranteeing the delivery by following the direction. The end result is an enhancement to the delivery ratio, of the sent to the received packet. This also allows the reduction in the number of control packets that need to be distributed, reducing the overall control overhead of the Improved Dream protocol

A Methodology for Deriving System Requirements Using Agent Based System Modeling

In this paper, we duscuss a method to derive the requirements for developing an Industrial Automation and Constrol System (IACS). An IACS has software components and associated hardware, which together implement the required monitoring, supervision and control of operations an a production plant. The requirements of such a system are multi-dimensional and may require multiple layers of abstraction. For this domain, we propose an agent-based modeling adopting an agent-based modeling approach is the implicit flexibility afforded by agents and the negotiation techniques that can be implemented to streamline the change management process associated with requirements modeling and analysis. This paper utilizes modeling constructs from UML/SysML to model and visualize the interactions among the agents. The types of agents and their roles are discussed in detail

Development of a Finite Element Model for the study of impact behaviour of sandwich panels

Sandwich structures based on Fibre Reinforced Polymer (FRP) skins bonded to either side of a low density core material, such as polymer foams are finding increasing use in aerospace and marine industries. It is necessary to study the impact response of sandwich structures in order to ensure the reliability and safety of these structures. It is particularly important due to the susceptibility of sandwich structures to damage, including Barely Visible Impact Damage (BVID) caused by foreign object impact. The study of the behaviour of sandwich structures to impact loading is usually accomplished by experimental testing, for example in a drop tower setup. However, experiments are time consuming and expensive. It requires instruments such as strain gauges and high speed cameras to find stress and deformation state of the structure. Experimental costs can be reduced by using numerical methods, which can help in predicting the energy absorption and peak loads for a given combination of materials and geometry. A finite element (FE) analysis provides the capability to model the impact event, including the contribution of the individual elements of the sandwich panel to the energy absorption. The damage inflicted on a sandwich plate is a complex phenomenon due to the different damage mechanisms involved: matrix cracking, tensile and compressive fibre breakage, delamination, core crushing and shear, etc. An accurate FE analysis requires including complex material models capable of capturing the mechanical behaviour of the facesheets as well as the core. The purpose of this work is to develop a numerical model of sandwich panels with Kevlar FRP facesheets and core of Rohacell foam, subjected to low velocity impact loading. An approach for modelling sandwich structures in the commercial finite element code LS-DYNA is presented. The force and energy absorption characteristics of the sandwich structure are analysed

Cost benefit analysis of computer aided engineering implementation in bespoke engineering business.

Advanced Computer Aided Engineering (CAE) is a field that expands continuously, concurrently with technology growth. Exceptional benefits are available by implementing the techniques in the business activities. Design capability is the biggest asset to any engineering organisation and it is more important to maintain and update constantly. It is evident that during 1990 to 2010, the pace of technology growth reached its peak value and contributes to rapidly improving business growth patterns. Despite many limitations, it is interesting to see a bespoke engineering firm improve in performance and their benefits coming from the implementation of these advanced CAE techniques.The thesis describes a two year partnership project between Sheffield Hallam University and Joseph Rhodes Limited, Wakefield in which 3-Dimensional Computer Aided Design (CAD) modelling, dynamic simulation, Finite Element Analysis (FEA) and 3D CAD animation were applied to four company machines i.e. rubber die press, knuckle joint press, HME Coining press and clay extrusion machine to enhance both pre- and post order processes. Direct cost savings of £114,000 were achieved due to savings in designer's time and materials for major components as a consequence of improved stress analysis.The project transformed the company's traditional method of 2D drawing methods to 3D methods with massive improvement in design standards. It also helps the designers to develop innovative design ideas with greater confidence and reliability. In addition to direct savings, improvements in tendering and quotation documentation due to 3D CAD were instrumental in increasing the overall company turnover by 300% from £7 million in 2007 to £21 million in 2010 with net profit averaged about £3 million. On conclusion of the project 6 designers were regularly using advanced CAE tools and techniques

Impact damage resistance of novel adhesively bonded natural fibre composite:Steel hybrid laminates

Synthetic fibre reinforcements are increasingly replaced with plant fibres but an improvement in the mechanical performance of biocomposites is required. Flax composite exhibits fibre failure and perforation even at low impact energies. This paper investigates the viability of improving the impact resistance of flax-epoxy biocomposite by hybridisation with a thin metal layer. High-speed cameras and optical microscopy were used to measure the dissipated energy and to identify the different damage modes. The impact response of hybrid biocomposites was compared to a reference GFRP composite and monolithic biocomposites and it was shown that the deformation and damage is significantly reduced in the hybrid configuration. Additionally, a numerical model was developed in Abaqus/Explicit and validated in terms of the displacement history and damage modes. The study reveals the effect of various material configurations and thicknesses on impact damage resistance and proves that the penetration resistance of biocomposites is improved by hybrid construction.publishedVersionPeer reviewe

Mechanical properties and structural health monitoring performance of carbon nanotube-modified FRP composites:A review

This article provides an extensive review of key publications covering topics of fabrication methods, enhancement of mechanical properties, and applications of CNT-modified FRP materials in structural health monitorin

Intraperitoneal rectal perforation presenting as fetal ascites – a rare occurrence

Spontaneous perforation of the rectum presenting as fetal ascites is an extremely rare occurrence. We report the case of an infant where antenatally detected fetal ascites was attributable to intraperitoneal rectal perforation. Investigations directed to identify common causes of this condition did not reveal any aetiology. Patient underwent surgical colostomy formation on day two of life, which was reversed at six weeks of age. We suggest that meconium ascites and peritonitis should be considered as differential diagnoses in fetuses with ascites and, if the neonate requires a laparotomy, the rectal area should be thoroughly inspected to exclude this entity