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Electrical and Computer Engineering (ICECE), 2010 International Conference on

Date 18-20 Dec. 2010

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Displaying Results 1 - 25 of 199
  • Author index

    Page(s): 1 - 7
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  • [Front and back cover]

    Page(s): c4
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  • [CD cover]

    Page(s): 1
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  • Technical sessions: ICECE 2010

    Page(s): 1 - 16
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  • [Front cover]

    Page(s): c1
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  • [Copyright notice]

    Page(s): 1 - 2
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  • ICECE 2010 Committees

    Page(s): 1 - 2
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  • Memristors based on an organic monolayer of molecules and a thin film of solid electrolytes

    Page(s): 761 - 764
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1079 KB) |  | HTML iconHTML  

    The memristor is a fundamental circuit element (along with capacitor, resistor and inductor) whose conductance is dependent on the previous functioning history. The concept was postulated almost four decades ago and was actually fabricated only recently. We report the fabrication of memristive junctions using an insulating film of a monolayer of cadmium stearate deposited using the Langmuir-Blodgett method in the gap of an inert electrode and a chalcogenide solid electrolyte. The thickness of the organic monolayer is about 2.8nm and its presence helps ensure a constant gap size between the electrodes. We used an energetic plasma process to create the chalcogenide solid electrolyte using sulfur (S) containing plasma for converting thin films of copper (Cu) into a mix of covelite phase CuS and chalcocite phase Cu2S. View full abstract»

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  • Analysis of resistances and transconductance of SiC MESFET considering fabrication parameters and mobility as a function of temperature

    Page(s): 5 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (778 KB) |  | HTML iconHTML  

    In this paper, we have analyzed the resistances (specific on-resistance and drain to source resistance) and transconductance of SiC MESFET. Source diffusion, channel, drift region, epi-layer and substrate resistances those contribute to the specific on-resistance have been analyzed. Effect of change in the junction depth due to post annealing on the implant range parameter is also considered. Half of change in the junction depth is added to the implant range parameter (before annealing). Straggle parameter is changed by diffusion coefficient and annealing time. Temperature dependency of mobility is also considered in all parameters. The variation of transconductance taking the drain to source voltage as a parameter has also been analyzed. Our analysis provides in-depth knowledge about the operation and characteristics of the high-power SiC MESFETs. View full abstract»

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  • Chromatic dispersion compensation using linearly chirped apodized fiber Bragg grating

    Page(s): 9 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (735 KB) |  | HTML iconHTML  

    In this paper, we have proposed an analytical model to compensate the chromatic dispersion in an optical transmission system using apodized fiber Bragg grating (FBG). Here we have presented an optimization process of the apodization strength factor of apodized FBG based dispersion compensation. It is demonstrated that a proper choice of the apodization strength factor results in minimum deviation of the dispersion from the required level and maximum reflection bandwidth. It is found that using a linear chirped hyperbolic tangent apodized FBG with apodization strength in the range of 0.7 - 0.8 can compensate dispersion up to 400ps. View full abstract»

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  • 3D temperature distribution of SiC MESFET using Green's function

    Page(s): 13 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (705 KB) |  | HTML iconHTML  

    A three-dimensional (3D) analytical model is derived in this paper to predict the temperature distribution in silicon carbide (SiC) MESFET. The analytical results are almost similar to the simulation results obtained by Atlas. The model describes the influence of the structural parameter and input power on temperature distribution. In some previous papers, analytical solution was obtained by the customary variable-separation method where a long calculation is needed. But by using Green's function, we get a model that is many times faster and even hand calculation is possible. The results can be used for optimization of the thermal design of SiC MESFET. View full abstract»

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  • AC properties of Mn0.5Zn0.5Fe2O4

    Page(s): 17 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (716 KB) |  | HTML iconHTML  

    Mn0.5Zn0.5Fe2O4 has been synthesized by the solid solution route. The synthesized sample was characterized by complex permeability, complex permittivity, complex impedance, conductance and quality factor. The complex permeability spectrum followed Snoke's law. The ac permittivity decreases monotonically with increasing frequency. The ac conductivity mechanism is discussed on the basis of a hopping electron model. View full abstract»

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  • Analysis of base transit time for a bipolar junction transistor considering base current

    Page(s): 20 - 24
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (889 KB) |  | HTML iconHTML  

    Consideration of base current makes the analytical modeling of base transit time for a bipolar junction transistor intractable, as such model requires knowledge of the majority hole current density, the recombination mechanism in the base and the injection of carriers from the base contact. All these effects along with bandgap narrowing, velocity saturation, Webster effect etc. makes the differential equation for minority carrier density third order or higher, nonlinear, non-homogeneous and of variable-coefficient. In this work, all these difficulties have been successfully overcome and therefore, an analytical model has been developed. The model results show that the consideration of base current increases the base transit time up to 5 - 8% even in the low-injection condition. View full abstract»

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  • Techniques of minimizing parasitics for the enhancement of modulation bandwidth of an oxide-confined VCSEL

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (686 KB) |  | HTML iconHTML  

    In this work, three different structures of a VCSEL e.g., (i) without any confinement, (ii) with oxide confinement and (iii) with oxide implantation have been investigated with the aim of improving the modulation performance. At first, same radius has been considered for both the active region and the oxide layer. For 3 mA injection current, a high modulation bandwidth is obtained for a VCSEL without any confinement compared to the above mentioned other two structures. Due to additional pole in the oxide-confined VCSEL the roll-off of the response curve increases and because of high parasitics the modulation bandwidth decreases. The parasitics of an oxide-confined VCSEL have been minimized by considering proton implantation in addition to the oxide layer. It is observed that due to such modification in the structure the modulation bandwidth of such a VCSEL increases. Next, for the same aperture radius the effect of variation of injection current on the modulation performance for the above mentioned three different structures of a VCSEL have been investigated with the aim of minimizing the parasitics for the enhancement of modulation bandwidth. It is found that with the increase of injection current the modulation bandwidth of a VCSEL increases by minimizing the parasitics. At 5.65μm aperture radius of an oxide-confined VCSEL a maximum modulation bandwidth of 9.5 GHz is obtained at an injection current value of 9 mA. In addition to this, the parasitics are also minimized by decreasing the radius of the oxide aperture of an oxide-confined VCSEL. A maximum modulation bandwidth of 10 GHz is obtained for an oxide-confined VCSEL by decreasing the oxide aperture radius up to 3μm at a value of injection current of 2.5 mA only. View full abstract»

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  • A single polarization fiber with ultra flattened dispersion and high birefringence

    Page(s): 25 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (751 KB) |  | HTML iconHTML  

    A novel design of a single polarization fiber is proposed in this work. The fiber comprises an elliptical core with a central air-hole and side air holes. Analysis of different polarization properties of the newly designed fiber has been performed both with and without the presence of thermal stress. The investigation shows that the new design has larger birefringence compared to conventional side-hole fiber. When thermal stress is taken into account, the fiber shows higher birefringence, no change in group velocity dispersion and lower polarization mode dispersion. These findings might serve as a ground for justification of the new design and also for its potential applications. View full abstract»

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  • A physically based compact model for eigenenergy in in rich In1−xGaxAs MOSFETs using modified Airy function approximation

    Page(s): 29 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1213 KB) |  | HTML iconHTML  

    We propose a compact model for calculating the quantized energy levels in InGaAs MOSFETs with Al2O3 gate dielectric. The model is based on the modified Airy function approximation, originally developed for Si nano-MOSFETs. The parameters of the model are extracted from numerical results calculated by self-consistent solution of one-dimensional Schrödinger and Poisson equation including the effect of wave function penetration into the gate dielectric. It is found that the compact model parameters are not sensitive to the variations in the In content in the channel layer and to the substrate doping density. Therefore, constant values of the parameters are proposed for both electrons and holes. View full abstract»

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  • Impact of chipshape on the performance of DS-OCDMA in dispersive fiber medium

    Page(s): 33 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB) |  | HTML iconHTML  

    Chipshape-dependent bit error rate (BER) performance of direct sequence optical code division multiple access is analytically studied in fiber optic communication with cascaded in-line optical amplifiers in presence of group velocity dispersion. In our analysis, supper-Gaussian, and Hyperbolic-Secant shaped optical orthogonal codes are employed as address sequence. Avalanche photodiode is used in an optical correlator receiver for optoelectronic conversion. The BER performance is determined as a function of received signal power, number of simultaneous users, and fiber length on account of receiver, optical amplifier, and multiuser access interference noises. The numerical results show that the BER performance of the system is highly dependent on the chipshape. The power penalty suffered by the system is evaluated at BER of 10-9. It is found that the proposed system suffered minimum penalty when Hyperbolic-Secant shaped chip used instead of supper-Gaussian shaped chip. View full abstract»

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  • Incoherent crosstalk analysis in fiber Bragg grating based optical add/drop multiplexer in optical networks

    Page(s): 37 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (744 KB) |  | HTML iconHTML  

    Wavelength division multiplexing (WDM) in optical fiber networks has gained wide acceptance as a means to handle the ever-increasing bandwidth demands of network users. An optical add-drop multiplexer (OADM) is an important device to add or drop wavelengths and crosstalk in OADM degrades the performance of WDM system. In this article we have developed an analytical model to study the incoherent crosstalk of a fiber Bragg grating based OADM. Results show that crosstalk, power penalty, relative intensity noise and bit error rate are minimum when the signals are added at Bragg wavelength and improve the system performance significantly. View full abstract»

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  • Outage probability of OFDMA based regenerative multihop transmission

    Page(s): 41 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (778 KB) |  | HTML iconHTML  

    This paper investigates outage probability of OFDMA multihop reverse links (from the mobile stations (MSs) to the base station (BS) through the intermediary relay stations (RSs)) under various conditions. A regenerative multihop relay network is considered between MS and BS. Flat Rayleigh fading scenarios are considered for each hop. Numerical results are obtained using two types of methods: deterministic simulation and partial Monte Carlo simulation. View full abstract»

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  • Reliability analysis of mobile communication system of Bangladesh

    Page(s): 45 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB) |  | HTML iconHTML  

    The use of mobile telephone in Bangladesh increased exponentially in the last couple of years. This paper presents an analysis of the reliability of mobile communication system of Bangladesh with a view to provide an idea about the reliability level of this system of communication to its customers as well as to its service providers. The analysis compares the reliability, in term of success rate, of mobile calls of different times of a day and also of different days of a week. It investigates the correlation between the reliability of mobile calls at different time and the traffic density at that time. The paper also compares the success rate of calls originating from or matured through different service providers. View full abstract»

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  • Design of a Duobinary encoder and decoder circuits for communication systems

    Page(s): 49 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (801 KB) |  | HTML iconHTML  

    This paper presents microcontroller based schematic circuit design of a complete duobinary encoder (duobinary code from binary bit) and duobinary decoder (binary from duobinary code) for data communication system. Binary code having two levels of bit sequence 1 and 0. On the other side Duobinary (DB) is a three-level code having 1, 0 and -1 levels. Using duobinary transmission instead of binary transmission, it can improve the system performance, bandwidth efficiency of output signal. View full abstract»

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  • Information-theoretic security in wireless multicasting

    Page(s): 53 - 56
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1504 KB) |  | HTML iconHTML  

    In this paper, a wireless multicast scenario is considered in which the transmitter sends a common message to a group of client receivers through quasi-static Rayleigh fading channel in the presence of an eavesdropper. The communication between transmitter and each client receiver is said to be secured if the eavesdropper is unable to decode any information. On the basis of an information-theoretic formulation of the confidential communications between transmitter and a group of client receivers, we define the expected secrecy sum-mutual information in terms of secure outage probability and provide a complete characterization of maximum transmission rate at which the eavesdropper is unable to decode any information. Moreover, we find the probability of non-zero secrecy mutual information and present an analytical expression for ergodic secrecy multicast mutual information of the proposed model. View full abstract»

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  • Analysis of Orthogonal Space-Time Block coding over Rayleigh fading channel

    Page(s): 57 - 61
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (809 KB) |  | HTML iconHTML  

    In this paper, a numerical method is presented to evaluate the bit error rate (BER) of different Orthogonal Space-Time Block Codes (OSTBCs) over Rayleigh fading channel for different transmission bit rate. The comparisons of Orthogonal Space-Time Block Codes are made with the equivalent uncoded Single-Input Single-Output (SISO) channel and uncoded space diversity. The result shows that a full rate code is more desirable than a lower rate code and OSTBC performs significantly over uncoded SISO channel and uncoded space diversity. View full abstract»

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  • Performance analysis of network coded bidirectional relaying in OFDM networks

    Page(s): 62 - 65
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    This paper focuses the performance of network-coded bidirectional relaying in OFDM networks. The fading channels between the base station-relay and relay-mobile station follow Rician and Nakagami-m distributions respectively. The outage probability expression is deduced for the non-identical-independent Rice-Nakagami-m fading channels. Neuro-Fuzzy based relay selection algorithm is used to select the best relay for the source and destination pair. The performance of the proposed network is compared with the traditional dual-hop network. Simulation results show that the network coded dual-hop system improves the throughput and network life time compared to the traditional dual-hop network. View full abstract»

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  • Electronics - what should we teach and why?

    Page(s): 66 - 69
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    The subject of electronics has developed so much over the years that the questions to be answered are: should Electronics be a one semester or two semester course, and what topics we should cover. The paper presents the issues to be considered in deciding on the course duration and the course topics. View full abstract»

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