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"A Non-Iterative Formulation for 2D Optical Waveguide Discontinuity Problems Based On Padé Approximants"
Get PDFIn this letter, we propose a simple non-iterative formulation for the analysis of optical waveguide discontinuity problems. The formulation, which is based on rotated branch cut Padé approximation scheme, is both accurate and efficient. It is computationally fast due to its non-iterative nature. The effectiveness of the proposed approach is demonstrated by modeling an optical waveguide air facet. Calculations show good agreement with previously published results
WIRELESS FAIR QUEUING ALGORITHM FOR WINDOW-BASED LINK LEVEL RETRANSMISSION
Get PDFWireless networks have unreliable channels that experience bursty and location-dependent errors. Several fair queuing algorithms have been proposed in order to provide QoS in presence of errors in a fair manner. However, most of these algorithms are unpractical as they require perfect channel predication or do not work well with the Link Layer. Wireless Fair Queuing with Retransmission (WFQ-R) algorithm was recently suggested to address these problems by penalizing flows that use wireless resources without permission in the link layer. However, the WFQ-R algorithm is based on Stopand- Wait LLR scheme which also costs the network extensive delay and low utilization. In this paper, a new wireless fair queuing based on the WFQ-R algorithm is proposed to work with the window-based error control schemes in the link layer. The proposed algorithm has shown outstanding results compared with WFQ-R in terms of lower queuing delay, better throughput and fairly allocated resources
Bypass AODV: Improving Performance of Ad Hoc On-Demand Distance Vector (AODV) Routing Protocol in Wireless Ad Hoc Networks
Get PDFA speaker verification system for Arabic
Get PDFIn this thesis a new Speaker Verification System (SVS) methodology is developed. The objective is to develop a SVS system that achieves high identification accuracy with low storage requirements for the use in smart card-based systems. This proposed system combines the advantages of the simple structure of text-dependent systems and the performance of text-independent systems. The feature extraction utilized the Mel-Frequency Cepstrum Coefficients MFCC for its superior performance, and user template is based on a Vector Quantization codebook for fast and efficient pattern classification. A new adaptive threshold is also proposed to achieve improved performance with time and to mitigate temporarily changes in speaker voice. The system is trained and tuned for Arabic speakers using initially certain parts from the holy Qura'an. A sample of eighteen Arabic speakers is used to evaluate the system performance. The system achieves an accuracy of 0.01 for the False Acceptance Rate (FAR), and 0.04 for the False Rejection Rate (FRR)
Parallel Inverse Halftoning by Look-Up Table (LUT) Partitioning
Get PDFLook-Up Table (LUT) method for inverse halftoning is computation less, fast, and also yields goods results. It employs a single LUT that is stored in a ROM and contains pre-computed contone (gray level) values for inverse halftone operation. This paper proposes an algorithm that can perform parallel inverse halftone operation by partitioning the single LUT into N smaller Look-Up Tables (s-LUTs). Thereby, upto k (k≤N) pixels can be concurrently fetched from the halftone image, and their contone values can also be fetched concurrently from separate smaller Look-Up Tables (s-LUT). The parallelization increases the speed of inverse halftoning by upto k times while the total entries in all s-LUTs remains equal to the entries in the single LUT of the serial LUT method. Some degradation in image quality is possible due to pixel loss during parallel fetching. This is due to some contone values cannot be fetched in the same cycle because some other contone value is being fetched from the s-LUT. The complete implementation of the algorithm requires two CPLD devices for computational portion, external content addressable memories (CAM) and static RAMs to store s-LUTs
"A novel current-mode OTA-C universal filter"
Get PDFA novel mixed-mode biquad circuit is presented. The circuit uses six single-output- and one dual-output-operational transconductance amplifiers, two grounded capacitors; and can realize lowpass, highpass, bandpass, notch, lowpass-notch, highpass-notch and allpass responses from the same topology. The circuit can be driven by voltage or current and its output can be voltage or current. The parameters o and o / Qo enjoy independent electronic tunability. Simulation results are included
A novel current-mode OTA-C universal filter Vol. 2, 2007, pp. 279-284
Get PDFA novel current-mode biquad circuit is presented. The circuit uses two single-output-, one multiple-output-operational transconductance amplifiers (OTAs), two grounded capacitors and can realize lowpass, highpass, bandpass, notch, lowpass notch, highpass notch and allpass responses from the same topology. The parameters ωo and ωo/Qo enjoy independent electronic tunability. Simulation results are include
"Diffraction of Surface Plasmon Modes on Abruptly Terminated Metallic Nanowires,"
No full textSurface plasmon polariton modes on cylindrical nanowires remain accessible for applications even when the wire radius is only a small fraction of the wavelength. Abrupt wire termination constitutes a basic discontinuity that underlies many of the wire functions. The diffraction of the surface plasmon modes by the discontinuity is investigated. The near field around the termination plane is determined with no simplifying assumptions of the physical aspects of the diffraction process. The transmitted and reflected fields are calculated for wires in vacuum. Full conversion of the surface plasmon mode energy into light is shown to occur at specific values of the wire radius
Assessing Readiness of IP Networks to Support Desktop Videoconferencing Using OPNET
Get PDFOPNET is a powerful network design and simulation tool that has gained popularity in industry and academia. However, there exists no known simulation approach on how to deploy a popular real-time network service such as videoconferencing. This paper demonstrates how OPNET can be leveraged to assess the readiness of existing IP networks to support desktop videoconference. To date, OPNET does not have built-in features to support videoconferencing or its deployment. The paper offers remarkable details on how to model and configure OPNET for such a purpose. The paper considers two types of video traffic (viz. fixed and empirical video packet sizes). Empirical video packet sizes are collected from well-known Internet traffic traces. The paper presents in-depth analysis and interpretation of simulation results and shows how to draw proper engineering conclusions