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Yang L.,Guangdong University of Technology | Yang L.,Nanjing Southeast University | Gao X.,Nanjing Southeast University | Alouini M.-S.,Electrical
IEEE Photonics Journal | Year: 2014

Free-space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short-range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over both weak and strong atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, average capacity, diversity order, and coverage are analyzed. Results show that the diversity order for the gamma-gamma fading is N min {α, β}/2, where N is the number of users, and α and β are the channel fading parameters related to the effective atmospheric conditions of the link. © 2009-2012 IEEE. Source

Pingle H.,Swinburne University of Technology | Wang P.-Y.,Swinburne University of Technology | Thissen H.,CSIRO | McArthur S.,Electrical | And 2 more authors.
Biointerphases | Year: 2015

Biofilm formation on medical implants and subsequent infections are a global problem. A great deal of effort has focused on developing chemical contrasts based on micro- and nanopatterning for studying and controlling cells and bacteria at surfaces. It has been known that micro- and nanopatterns on surfaces can influence biomolecule adsorption, and subsequent cell and bacterial adhesion. However, less focus has been on precisely controlling patterns to study the initial bacterial attachment mechanisms and subsequently how the patterning influences the role played by biomolecular adsorption on biofilm formation. In this work, the authors have used colloidal self-assembly in a confined area to pattern surfaces with colloidal crystals and used them as masks during allylamine plasma polymer (AAMpp) deposition to generate highly ordered patterns from the microto the nanoscale. Polyethylene glycol (PEG)-aldehyde was grafted to the plasma regions via "cloud point" grafting to prevent the attachment of bacteria on the plasma patterned surface regions, thereby controlling the adhesive sites by choice of the colloidal crystal morphology. Pseudomonas aeruginosa was chosen to study the bacterial interactions with these chemically patterned surfaces. Scanning electron microscope, x-ray photoelectron spectroscopy (XPS), atomic force microscopy, and epifluorescence micros­copy were used for pattern characterization, surface chemical analysis, and imaging of attached bacteria. The AAMpp influenced bacterial attachment because of the amine groups displaying a positive charge. XPS results confirm the successful grafting of PEG on the AAMpp surfaces. The results showed that PEG patterns can be used as a surface for bacterial patterning including investigating the role of biomolecular patterning on bacterial attachment. These types of patterns are easy to fabricate and could be useful in further applications in biomedical research. © 2015 American Vacuum Society. Source

Roy R.B.,University of Flensburg | Rokonuzzaman M.,Electrical | Hossam-E-Haider M.,Bangladesh Institute of Technology
2nd International Conference on Electrical Engineering and Information and Communication Technology, iCEEiCT 2015 | Year: 2015

Transformer is an indispensable component of power system which performs many functions such as voltage transformation, electrical isolation, noise decoupling and power quality improvement. However, at low frequencies (60/50 Hz), it is a bulky and expensive component. In this paper, the concept of electronic transformers is further extended and explored for its suitability in power systems. Though from the perspective of input/output behavior, the electronic transformer and the conventional transformer are identical but the PET has reduced size, losses, higher efficiency, improved voltage regulation and reduced voltage sag in comparison to those of conventional transformer. In the proposed design, three phase full wave converter and inverter are incorporated in both primary and secondary sides of the high frequency transformer. The PWM (pulse width modulation) is used for switching which manages synchronism between input and output and suppresses harmonics. The matrix converter is used in the proposed design which uses SVPWM (space vector pulse width modulation) for multiple switching. The SVPWM ensures maximum voltage transfer without harmonics in the output. The design and analysis of the proposed model of PET is done by using MATLAB-SIMULINK. It can be inferred from the steady state analysis of the simulation results that the PET has better voltage regulation than that of the conventional transformer. © 2015 IEEE. Source

Shukla P.,BITS Pilani Goa Campus | Ghodki D.,BITS Pilani Goa Campus | Manjarekar N.S.,Electrical | Singru P.M.,BITS Pilani Goa Campus
IFAC-PapersOnLine | Year: 2016

Minimization of car vibrations has been a topic of research over the years and many control strategies have been developed. Therefore, there needs to be a method for active vibration control in cars. This paper presents two methods for designing the controller for a quarter car model which would help in minimizing car vibrations and increasing passenger comfort subjected to road disturbances. The methodologies used are H-infinity and H-2 optimal control. The main aim of this article is to design a controller to control the response of a quarter car model to various road inputs. This is a non-linear model with 2 degrees of freedom. It is linearized and modelled as a disturbance rejection (regulatory) problem wherein the effect of disturbances are minimised. Different weighing functions have been considered to take the impact of road disturbances into account. The results are compared with the Proportional Integral Derivative (PID) controller designed using the same system parameters and performance specifications. The behaviour of the open loop and closed loop system is observed by examining the impulse and frequency responses in MATLAB. A detailed discussion is done with the choice of weighing functions. It is found that the disturbance rejection techniques suggested in this paper help in improving the system response. © 2016, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. Source

Rahmat M.F.,University of Technology Malaysia | Isa M.D.,Politeknik Kota Bharu | Sheikh U.U.,University of Technology Malaysia | Raja Hussin T.A.,Politeknik Kota Bharu | And 2 more authors.
International Journal of Tomography and Statistics | Year: 2011

Accuracy and stability of the image being reconstructed are very crucial in an electrical charge tomography system (EChT). To obtain the quality and quantitative information from the cross-sectional images of the solid flow materials in conveyor pipeline, a suitable reconstruction method is needed for EChT. The problem with the methods introduced before such as linear back projection (LBP), filtered back projection (FBP) and least square (LS) methods is that they are ill-posed due to the ill-conditioning of sensitivity matrix produced in the forward modeling. Thus, the images introduced by these methods are not accurate. This paper will introduce CCD Camera as an alternative method to generate image concentration profile of material distribution in gravity-dropped conveyor pipeline using digital image technique. This technique is easy to set up and is not influenced by environmental disturbances such as humidity, charge static, noise and others. This alternative method has been tested in electrical charge tomography measurement system. The results show that the image concentration profiles obtained from this technique is better than the image reconstructed by LBP and FBP methods. © 2011 by IJTS (CESER Publications). Source

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