Design of a Dual-Band Sectoral Antenna for Hiperlan2 Application Using Double Layers of Metallic Electromagnetic Band Gap (M-EBG) Materials as a Superstrate

A novel design of a sectoral antenna that utilizes a double layer Metallic Electromagnetic Band Gap (M-EBG) as a superstrate for dual band directivity enhancement is presented in this paper. We obtain the different operating frequencies by adjusting the distance of the lower M-EBG layer from printed patch antenna and also the height between upper and lower M-EBG layers. This antenna operates according to a sectoral radiation pattern form presenting a half power beamwidth of at least 60∘. The proposed structure presents more than 17 dB directivity enhancement at 5.25 GHz and 5.65 GHz as compared to those of a patch antenna with 9 dB directivity. The principle is explained and applied to a Hiperlan2 antenna

Self-Powered Wireless Sensing for Smart Infrastructure

Effective sensing of environmental parameters or conditions rely on wireless connectivity of spatially distributed autonomous sensors to acquire and transmit data to a main location. To date, the majority of sensing and wireless transmission devices rely on wired connections or batteries that require periodic replacement, which is not entirely true to the concept of an autonomous embedded sensing network. Advances made towards the development of low-power microcontrollers, sensing devices and ultra low-power wireless technologies open the opportunity for substituting depletable batteries with low levels of locally-harvested kinetic, light, or thermal energy to power the sensing and transmission functions of a network. The predominant approach to using locally-harvested power has been to use an auxiliary harvester, solar or mechanical power, to operate vibration or ow sensing and transmission devices. In contrast, it would be more advantageous, in terms of size or volume of sensing element or in terms of availability of power, to use the same device to sense a physical quantity over a specific time period and to harvest energy that can be used to operate itself as a sensor and to power the transmission of the acquired signal over other periods. In this work, we will present examples of self-powered wireless sensors of air speed, water flow and vibrations

Multi-Fidelity Modeling and Simulation of Wave Energy Converters

Equations governing the response of wave energy converters (WECs) consist of partial differential equations and nonlinear boundary conditions that model the wave absorption, which is commonly used for classification of WECs, wave radiation and diffraction as required for prediction of wave energy generation by WEC farms, the converter’s response and the transduction mechanism. To date, the modeling and simulation of WECs or WEC arrays are based on linear wave theory, which assumes irrotational flow and limits the analysis for design to small wave amplitudes. In contrast, it is desirable to operate WECs in large waves under resonance conditions that would lead to large amplitude motions for effective energy conversion. With large amplitude waves and motions or responses, the linear and irrotational flow assumptions would not be valid. In this talk, we present a review and examples of (1) physics-based multi-fidelity modeling and simulation procedures that could be performed to develop effective control and optimization strategies for different types of WECs, and (2) nonlinear phenomena that can be exploited to enhance the performance of WECs

Homogenization of dislocation dynamics

In this paper we consider the dynamics of dislocations with the same Burgers vector, contained in the same glide plane, and moving in a material with periodic obstacles. We study two cases: i) the particular case of parallel straight dislocations and ii) the general case of curved dislocations. In each case, we perform rigorously the homogenization of the dynamics and predict the corresponding effective macroscopic elasto-visco-plastic flow rule

Near-forward Raman scattering by bulk and surface phonon-polaritons in the model percolation-type ZnBeSe alloy

We study the bulk and surface phonon-polaritons of the Zn0.67Be0.33Se zincblende alloy by near-forward Raman scattering. The short (Be-Se) bond exhibits a distinct percolation doublet in the conventional backscattering Raman spectra, corresponding to a three-mode behavior in total [1(Zn-Se),2(Be-Se)] for Zn0.67Be0.33Se. This offers an opportunity to achieve a refined understanding of the phonon-polariton modes of a zincblende alloy beyond the current two-mode approximation, corresponding to a [1(Zn-Se),1(Be-Se)] description in the present case. The discussion is supported by contour modeling of the Raman signals of the multi-mode bulk and surface phonon-polaritons within the formalism of the linear dielectric response

An integrated life cycle costing database: a conceptual framework

Life cycle costing (LCC) is a management technique that has been available to the industry for some time, but despite this it continues to languish in obscurity. Some clients, most apparently from the public sector, are fostering the technique by commissioning studies based on the LCC appraisal techniques. However, the majority of building designs are still currently produced unsullied by thoughts of maintenance implications, life expectancy or energy consumption. Recent technological developments, particularly in Web, Virtual Reality (VR), and Object Oriented technologies and mathematical and computational modelling techniques will undoubtedly help in resolving some of the problems associated with life cycle costing techniques. This paper outlines a conceptual framework for an innovative system that facilitates the implementation of LCC in various design and occupancy stages. This system is being developed within an EPSRC-funded research project, undertaken through a joint collaboration between the Robert Gordon University and the University of Salford

Generation of Bianchi type V cosmological models with varying Λ\Lambda-term

Bianchi type V perfect fluid cosmological models are investigated with cosmological term $\Lambda$ varying with time. Using a generation technique (Camci {\it et al.}, 2001), it is shown that the Einstein's field equations are solvable for any arbitrary cosmic scale function. Solutions for particular forms of cosmic scale functions are also obtained. The cosmological constant is found to be decreasing function of time, which is supported by results from recent type Ia supernovae observations. Some physical aspects of the models are also discussed.Comment: 16 pages, 3 figures, submitted to CJ

The Non-Trivial Effective Potential of the `Trivial' lambda Phi^4 Theory: A Lattice Test

The strong evidence for the `triviality' of (lambda Phi^4)_4 theory is not incompatible with spontaneous symmetry breaking. Indeed, for a `trivial' theory the effective potential should be given exactly by the classical potential plus the free-field zero-point energy of the shifted field; i.e., by the one-loop effective potential. When this is renormalized in a simple, but nonperturbative way, one finds, self-consistently, that the shifted field does become non-interacting in the continuum limit. For a classically scale-invariant (CSI) lambda Phi^4 theory one finds m_h^2 = 8 pi^2 v^2, predicting a 2.2 TeV Higgs boson. Here we extend our earlier work in three ways: (i) we discuss the analogy with the hard-sphere Bose gas; (ii) we extend the analysis from the CSI case to the general case; and (iii) we propose a test of the predicted shape of the effective potential that could be tested in a lattice simulation.Comment: 22 pages, LaTeX, DE-FG05-92ER40717-

Oral manifestations of inflammatory bowel disease

Inflammatory bowel diseases (IBD), including Crohn\u2019s disease and ulcerative colitis, have important extraintestinal manifestations, notably in the oral cavity. These oral manifestations can constitute important clinical clues in the diagnosis and management of IBD, and include changes at the immune and bacterial levels. Aphthous ulcers, pyostomatitis vegetans, cobblestoning and gingivitis are important oral findings frequently observed in IBD patients. Their presentations vary considerably and might be well diagnosed and distinguished from other oral lesions. Infections, drug side effects, deficiencies in some nutrients and many other diseases involved with oral manifestations should also be taken into account. This article discusses the most recent findings on the oral manifestations of IBD with a focus on bacterial modulations and immune changes. It also includes an overview on options for management of the oral lesions of IBD