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International Symposium on Telecommunications, IST

作者： Hossein Hatefi Ardakani Zahra Ghattan Kashani Mohammad Keramat Amirkalaee Jalil Rashed-Mohassel Iran Telecommunications Research Center Tehran Iran Center of Excellence on Applied Electromagnetic Systems Electrical and Computer Engineering Department University of Tehran Tehran Iran

In this paper, a generic multilayer structure containing metals, dielectrics and graphene sheets is considered and analyzed. The spectral domain techniques (SDTs) have been known as an efficient method for analysis of planar structures. But since the existence of graphene sheet imposes a new boundary condition; the conventional SDTs cannot deal with it. Therefore, a spectral-based method is proposed by applying the two dimensional Fourier transform to the fields equations. First, without loss of generality, a graphene sheet described with a conductivity tensor is assumed to be placed between two arbitrary dielectric layers. A generalized transformation matrix is then calculated where relates the electromagnetic fields of the top layer in terms of the ones of the bottom layer. It is shown that considering the tangential electric fields as supporting field components makes an easier analysis and results in more simplified expressions. The proposed method is evaluated through some examples. Some novel characteristics are observed which are promising in providing new applications.

关键词： Graphene Equations Dielectrics Conductivity Nonhomogeneous media Mathematical model Electric fields

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Cross-layer throughput optimization for delay and QoS constrained applications

Cross-layer throughput optimization for delay and QoS constr...

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MILCOM, Military Communications Conference

作者： E. Adebola O. Olabiyi A. Annamalai Center of Excellence for Communication Systems Technology Research (CECSTR) Department of Electrical and Computer Engineering Prairie View A and M University TX USA

In this article we recast the problem of throughput optimization in cross-layer architecture for delay sensitive applications. Unified mathematical framework was developed for maximizing user throughput in generalised wireless environment. The optimization variables adapted include symbol rate (at the application layer), packet length (at the MAC layer), constellation size (at the physical layer) and number of retransmissions of M-PSK digital modulation schemes. We derive optimization equations for each of the above degrees of freedom in closed-form which maximizes the throughput subject to a prescribed packet loss probability constraint. Interior-point optimization algorithm was used to solve the resultant constrained non-linear optimization problem. Numerical results reveal that no successful packet decoding is possible at very low average signal-to-noise (SNR) regime as the packet loss constraint is not met when channel condition is very bad irrespective of adaption. At moderately low SNR, it is sufficient to adapt packet length while keeping symbol rate fixed at the maximum value while joint optimization of both the number of retransmissions and the constellation size parameters while keeping the packet length at an appropriate value is required in the high average SNR regime, to achieve maximum throughput over a myriad of wireless fading environments. Results also showed that the tighter the packet loss constraint, the lower the throughput becomes.

关键词： Decision support systems

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Joint-design of PHY/MAC layers for throughput optimization

Joint-design of PHY/MAC layers for throughput optimization

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Consumer Communications and Networking Conference, CCNC IEEE

作者： O. Olabiyi E. Adebola A. Annamalai O. Odejide Center of Excellence for Communication Systems Technology Research (CECSTR) Department of Electrical and Computer Engineering Prairie View A and M University TX USA

This article develops a unified analytical framework for maximizing the user throughput of a cooperative multi-relay network over generalized wireless channels using the symbol rate, packet length and constellation size of M-ary PSK/QAM digital modulation schemes as optimization variables. Optimization equations for each of the above degrees of freedom are derived in closed-form. A low-complexity discrete optimization algorithm for finding the “optimal” parameter-triplet is also developed to solve the resulting non-linear joint optimization problem. Numerical results reveal that it is sufficient to adapt the number of cooperating relay nodes as well as the symbol rate in the low SNR regime while a joint-optimization of both the packet length and the constellation size parameters is desirable in the high SNR regime to achieve the maximum throughput.

关键词： Signal to noise ratio Throughput Relays Optimization Fading Modulation Equations

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Linear regression based statistical approach for detecting proportion of component gases in manhole gas mixture

Linear regression based statistical approach for detecting p...

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International Symposium on Physics and Technology of Sensors (ISPTS)

作者： Varun Kumar Ojha Paramartha Dutta Hiranmay Saha Sugato Ghosh Department of Computer & System Sciences Visva-Bharati University Santiniketan India Center of Excellence for Green Energy & Sensor Systems Bengal Engineering & Science University Shibpur India

The present article proposes the issues in designing an intelligent recognizer for detecting proportion of component gases in manhole gas mixture. The major components found in manhole gas mixture are Hydrogen Sulfide (H 2 S), Ammonia (NH 3 ), Methane (CH 4 ), Carbon Dioxide (CO 2 ), Nitrogen Oxide (NO x ), and Carbon Monoxide (CO). The manhole gas is formed after the decomposition of waste products, domestic garbage etc. into the sewer pipelines which are built for exhausting these waste products out of our cities and towns. The manholes are built across these pipelines for cleaning purpose. Thus safety for the people working in this field is a matter of concern because all the above mentioned gases are harmful gases and they are potent to loss of human lives. Also detection of these gas components is of primary concern today as because a short exposure of these components with human physiology results endanger to their lives. So our focus is on developing an intelligent gas recognition system which can recognize multiple gases simultaneously. A gas sensor array is an array of sensors, consisting of two or more electrical type semiconductor gas sensors. Response of electrical type semiconductor gas sensors in presence of gases are either the change in resistance or change in voltage of the sensor. At an instant a gas sensor array contains as many sensors as many individual gases we are targeting to detect. Use of multiple gas sensors and presence of multiple gases together results cross-sensitivity. The cross-sensitivity is an overlapping effect of one gas on another sensor. We adopt linear regression based statistical approach to deal with issues of simultaneous detection of multiple gases notwithstanding cross-sensitivity issue.

关键词： Gas detectors Gases Sensor arrays Linear regression Sensitivity

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TDIE solver based on novel closed-form time-domain Green's functions for half-space problem

TDIE solver based on novel closed-form time-domain Green's f...

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International Symposium on Antenna Technology and Applied Electromagnetics and the Canadian Radio Science Meeting, ANTEM/URSI

作者： Amir Nader Askarpour Mohsen Ghaffari-Miab Reza Faraji Dana Felipe Valdés Eric Michielssen Center of Excellence on Applied Electromagnetic Systems School of ECE College of Engineering University of Tehran Tehran Iran Electrical Engineering and Computer Science Department University of Michigan Ann Arbor MI USA

New closed-form expressions for time-domain Green's functions (TDGFs) for sources and observers residing in the interface of a half-space medium are presented. The proposed closed-form TDGF's characterize scalar and vector potentials due to infinitesimal horizontal electric dipoles with Dirac delta temporal signature. The closed-form TDGFs are numerically validated by comparison with data derived using the Cagniard-de Hoop method. They also are used in a high-order accurate, marching-on-in-time-based time-domain integral equation (TDIE) solver. This TDIE solver calls for the computation of convolutions of TDGFs with temporal basis functions. Here, these convolutions too are cast in closed-form, assuming that the temporal basis function is a quadratic B-Spline (QBS). Numerical examples that demonstrate the applicability of the proposed scheme to the problem of scattering from planar PEC structures residing in the interface of a half-space medium are presented.

关键词： Vectors Electric potential Time domain analysis Green's function methods Equations Observers Educational institutions

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Spin-3 quasinormal modes of the BTZ black hole

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Physical Review D 2012年第8期85卷 084007-084007页

作者： Yun Soo Myung Yong-Wan Kim Young-Jai Park Institute of Basic Science and School of Computer Aided Science Inje University Gimhae 621-749 Korea Department of Physics and Center for Quantum Spacetime Sogang University Seoul 121-742 Korea Department of Service Systems Management and Engineering Sogang University Seoul 121-742 Korea

Using the operator approach, we obtain quasinormal modes (QNMs) of the Bañados-Teitelboim-Zanelli black hole in spin-3 topologically massive gravity by solving the first-order equation of motion with the transverse-traceless condition. We find that these are different from those obtained when solving the second-order differential equation for the third-rank tensor of spin-3 field subject to suitable boundary conditions and having the sign ambiguity of mass. However, it is shown clearly that two approaches to the left-moving QNMs are identical, while the right-moving QNMs of solving the second-order equation are given by descendants of the operator approach.

关键词： BLACK holes (Astronomy) NUCLEAR spin ASTROPHYSICS GRAVITY DIFFERENTIAL equations BOUNDARY value problems OPERATOR theory

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Carbon-Nanotube-Based FR-4 Patch Antenna as a Bio-Material Sensor

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Procedia engineering 2012年 41卷 724-728页

作者： Ahmad Mohammadi Alyani Ismail Mohd Adzir Mahdi Raja Syamsul Azmir Raja Abdullah Maryam Mohd Isa Amir Reza Sadrolhosseini Department of Computer and Communication Systems Engineering Faculty of Engineering Universiti Putra Malaysia 43400 Selangor Malaysia Department of Electrical & Electronics Engineering Faculty of EngineeringUniversiti Putra Malaysia 43400 Selangor Malaysia Center of Excellence for Wireless and Photonics Networks (WiPNet) Faculty of Engineering Universiti Putra Malaysia 43400UPM Serdang Malaysia

This paper presents the development and design of proximity coupled feed patch antenna as a bio-sensor. This sensor system consists of a two-layer Flame Retardant (FR-4) patch antenna coated with Multi Walled Carbon Nanotubes (MWCNTs) for absorbing bio-molecules. The best design of patch antenna is chosen based on simulation results using computer Simulation Technology (CST) microwave studio software. After adding bio-material on the top of antenna and interaction with MWCNTs based on the changes in the effective dielectric constant, the resonant frequency of patch antenna is changed. Experimental results have shown 1 MHz change in resonant frequency of patch antenna upon exposure to ethanol. Based on operating frequency (5 GHz) this technique can be used in network sensor systems to measure bio-materials in future research.

关键词： Bio sensor patch antenna carbon nanotube sensor microwave sensor

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Detection of Proportion of Different Gas Components Present in Manhole Gas Mixture Using Backpropagation Neural Network

Detection of Proportion of Different Gas Components Present ...

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2012 International Conference on Information and Network Technology (ICINT 2012)

作者： Varun Kumar Ojha Paramartha Dutta Hiranmay Saha Sugato Ghosh Department of Computer and System Sciences Visva Bharati University SantiniketanWest BengalIndia Center of Excellence for Green Energy & Sensor Systems Bengal Engineering & Science University ShibpurWest BengalIndia

The article presents a concept of implementing an Intelligent System for detection of proportion of different components present in manhole gas *** determination of proportion of components in manhole gas mixture is important because the manhole gas mixture contains many poisonous gases namely Hydrogen sulfide (H 2 S),Ammonia (NH 3),Methane (CH 4),Carbon Dioxide (CO 2),Nitrogen Oxide (NO x),and Carbon Monoxide (CO).A very limited time exposure to any of these components with human beings may endanger their lives.A gas sensor array is used for recognition of multiple gases *** an instance the manhole gas mixture may contain many hazardous gas *** it is wise to use specific gas sensor for each gas component in the gas sensor *** of multiple gas sensors and presence of multiple gases together result in *** have used backpropagation algorithm to resolve the multiple gas detection and cross-sensitivity issue quite effectively.

关键词： manhole gas mixture,gas sensor array,cross-sensitivity,backpropagation

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Understanding mobile phone battery - Human interaction for developing world A perspective of feature phone users in Africa

Understanding mobile phone battery - Human interaction for d...

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Baltic Congress on Future Internet Communications (BCFIC Riga)

作者： Amandeep Dhir Puneet Kaur Nobert Jere Ibrahim A Albidewi Department of Computer Science and Engineering School of Science Aalto University Finland Department of Information and Service Economy School of Economics Aalto University Finland Telkom Center of Excellence in ICTD Computer Science Department University of Fort Hare South Africa Information Systems Department King Abdulaziz University Saudi Arabia

Mobile phone battery is well recognized as an open usability concern for both device manufacturers and end users. Due to the ubiquitous nature of mobile phones, battery related problems have received increasing attention in the scientific conferences. In our paper, we have presented the need for understanding and investigating Human Battery Interaction for Development (HBI4D). In our study we are mainly interested in the non-smartphone or feature phone users who belong from low income; low literacy and resource limited areas. This would enable us in understanding the existing design opportunities available for developing and designing energy efficient mobile battery solutions for emerging markets. Our work is first of its kind as almost all the existing work on battery efficiency is targeted towards smartphone users from western world. However, our work mainly comprises of users from emerging markets such as India, China and South Africa.

关键词： Batteries Mobile handsets Mobile communication Humans Energy efficiency Communities Educational institutions

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Design guidelines for pervasive computing: Implications of technology use in Africa

Design guidelines for pervasive computing: Implications of t...

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IEEE Annual Conference on Pervasive Computing and Communications Workshops (PerCom)

作者： Amandeep Dhir Nobert Jere Puneet Kaur Mikko Heiskala Ibrahim A Albidewi Daniyal M Alghazzawi Department of Computer Science and Engineering School of Science Aalto University Finland Telkom Center of Excellence in ICTD Computer Science Department University of Fort Hare South Africa Department of Information and Service Economy School of Economics Aalto University Finland Information Systems Department King Abdulaziz University Saudi Arabia

The fast economic growth lead by worlds emerging markets, has created the need for designing suitable Pervasive technology (aka PerComp), aimed at emerging markets. However, for designing suitable PerComp, it is essential to understand the implications of PerComp technology use in emerging market context. We studied information sharing practices and implications of technology use in two rural communities of South Africa. This enabled us in understanding some of the central issues significant for designing suitable PerComp for these markets. We found ICT is in abundance but still underutilized, oral communications are preferred means of sharing information and need for an invisible technology. In order to achieve the socio-economic progress of low income, low literacy and resource constraint regions of emerging market, it is important to first understand the implications of technology use before designing any technology aiming at these markets.

关键词： Communities Mobile handsets Privacy Educational institutions Oral communication Context Internet

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