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Electrical Engineering, 2008. ICEE 2008. Second International Conference on

Date 25-26 March 2008

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Displaying Results 1 - 25 of 64
  • A comparative evaluation of hybrid input current waveshaping methods for single-phase rectifier

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (722 KB) |  | HTML iconHTML  

    This paper presents a comparative evaluation of hybrid current waveshaping methods for single-phase rectifier. The simulation results show that the hybrid method can further lower the input current components and THDi of a single-phase diode rectifier as compared with the three passive current waveshaping method by P. D. Ziogas, Ji Yanchao (improved method-1) and H. A. Kazem (improved method-2) . Still the same sequence for improvement is valid in the case of hybrid methods. The relevant input current and voltage waveforms, the input current total harmonic distortion and the input power factor value are derived from the computer simulation or theoretical analysis. View full abstract»

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  • A Gm-C anti-aliasing filter for digital radio receivers

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (507 KB) |  | HTML iconHTML  

    Analog integrated filters are mainly used in a stage prior to A/D convertors in analog-digital systems as anti-aliasing filters. This paper presents a 3rd order transconductance-C (Gm-C) anti aliasing filter (AAF) as part of the front-end analog circuits of DRB receivers. In the present work we have minimized the power consumption and the number of transistors in such circuits. The anti-aliasing filter is designed and simulated using 0.18 um CMOS technology. The circuit consumed 233.25 micro Watts through a 1.8 V power supply with a cut-off frequency of 22.5 MHz. View full abstract»

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  • A method for coverage control in wireless sensor networks with two degrees of freedom

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (537 KB) |  | HTML iconHTML  

    Sensor networks specifications are highly dependent on the application defined for the network. In this paper we tried to achieve a predefined coverage percentage using a simple selection algorithm in order to cover the desired percentage using a minimum number of active sensors and thus achieving to a higher life time for the whole network. The main advantage of this sensor-based algorithm is its selections that do not need a centralized coordination and thus increase the independence of each node from the whole network. In addition the networkpsilas robustness is increased and it becomes more resistant to unpredictable problems. Another advantage of the algorithm is that it does not need any sensor to locate the geographic location of each node. This algorithm leads finally to the possibility of more application and better usage of a presented wireless sensor network. View full abstract»

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  • A multi-channel wideband direct-conversion receiver using synchronization signal from a tunable injection locked oscillator

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (619 KB) |  | HTML iconHTML  

    Synchronization is a challenging issue facing industrial designers that has not been researched often by academic researchers. The conventional techniques are phase-locked loop (PLL), digital PLL, or direct-digital synthesis (DDS). With any one or a combination of these techniques, high performance can be achieved at the expense of complexity or cost. In this paper, another technique, the injection locking technique, is explored to provide synchronization for a direct-conversion receiver. More specifically, signal synchronization is achieved with a selectable dielectric-resonator injection locked oscillator (DRILO) designed at a free running frequency of 3.634 GHz. The receiver developed was able to recover the carrier and IQ signals from 3.58 GHz, 3.63 GHz and 3.69 GHz with 50 Msps to 63 Msps QPSK modulated signals. The receiver designed as such is novel and simple, and can find applications in many modern communications such as WiMax. It can also overcome frequency synchronization problems faced in OFDM systems. View full abstract»

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  • A new algorithm for voice activity detection based on wavelet packets

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1227 KB) |  | HTML iconHTML  

    Speech constitutes much of the communicated information; most other perceived audio signals do not carry nearly as much information. Indeed, much of the non-speech signals maybe classified as dasianoisepsila in human communication. The process of separating conversational speech and noise is termed voice activity detection (VAD). This paper describes a new approach to VAD which is based on the wavelet packet transform (WPT). Our algorithm utilizes the differences between spectral distribution of human speech (voice) and general noise. First, the algorithm performs wavelet transform on the signal resulting in its decomposition into subbands using coefficients of WPT, then it detects the voice within the signal by comparing the subband energy of components between detail and approximation coefficients. Computer simulation results are given to illustrate the effectiveness of our new VAD algorithms. View full abstract»

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  • A new method for summation of short time CAF’s based on RLCS motion

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (789 KB) |  | HTML iconHTML  

    Cross ambiguity function is a common method for joint estimation of TDOA/FDOA. CAF performance degrades in wideband situation. The maximum likelihood estimator in wideband model contains data resampling. Because of intensive computational burden data resampling isnpsilat viewed as a practical method. Calculation of short time CAFs and summation of them is suggested as a practical alternative method. Different summation methods were suggested for compensation of TDOA variation in the integration time. In this paper first with an experimental test we find the areas in which FDOA variations is noticeable and we indicate that these regions are big enough not to be ignored. Then a new method for summation of sequential CAFs is presented. The proposed method compensates variation of both TDOA and FDOA together and via this method, detection ability of peak in combined CAF is improved. The proposed method is based on recti linear constant speed (RLSC) motion. View full abstract»

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  • A novel control scheme for voltage multiplier based X-ray power supply

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1130 KB) |  | HTML iconHTML  

    A dual-mode input voltage modulation (IVM) control scheme for a three-phase ZCS series resonant (SR) inverter fed three-phase voltage multiplier based DC-DC converter for X-ray power generator is proposed. The three-phase ZCS SR inverter is formed by connecting three single-phase ZCS SR inverters in parallel and delaying the gating signals by 120deg with respect to each other. It operates at constant frequency & duty ratio. The lower arms of all the three single-phase inverters (i.e. which make three-phase ZCS-SR inverter) are connected to a common holding capacitor CH and the voltage VH across it, is controlled by a control circuit. At the turn ON of the converter, the control circuit clamp voltage VH to 0V, causing inverter to see full input voltage and output voltage to rise with maximum speed. As the output voltage reaches 80% of target voltage value, the voltage VH is raised from 0V to (VH)ref, thereby reducing the effective input voltage to inverter. As a result the rise rate of output voltage slow downs and the over shoot is prevented. Experimental results based on the laboratory scale-down prototype are presented to verify the effectiveness of proposed dual-mode IVM control scheme. View full abstract»

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  • A PSCAD/EMTDC model for distributed static series compensator (DSSC)

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (743 KB) |  | HTML iconHTML  

    This paper presents a detailed PSCAD/EMTDC simulation model of the distributed static series compensator (DSSC); A small, light weight cylinder that clamps directly onto the transmission line conductor and has the ability to alter the impedance of the power lines in order to increase power transfer capability and maximize economic value of the transmission system. The DSSC has the potential to function like a SSSC (static synchronous series compensator) but at a much lower cost and higher reliability, however more testing is needed before wide scale deployment. Hence a graphic-based model suitable for electromagnetic transient studies is presented in the professionalpsilas tool for power system simulation program PSCAD/EMTDC which can be a starting point to carry out extensive simulation studies. The performance and accuracy of the model is validated by simulation and comprehensive results are presented. View full abstract»

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  • A robust voice activity detection based on wavelet transform

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (856 KB) |  | HTML iconHTML  

    Voice activity detection is an important step in some speech processing systems, such as speech recognition, speech enhancement, noise estimation, speech compression ... etc. In this paper a new voice activity detection algorithm based on wavelet transform is proposed. In this algorithm we use the energy in each sub band, and by two methods we extract feature vector from these values. Experimental results demonstrate advantage over different VAD methods. View full abstract»

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  • A transform domain based Least Mean Mixed-Norm algorithm to improve adaptive beamforming

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB) |  | HTML iconHTML  

    In this paper, an adaptive beamforming algorithm based on least mean mixed norm (LMMN) algorithm and self-orthogonalizing transform is presented. In the proposed algorithm, LMMN is used to improve the convergence rate of conventional LMS algorithm. Whereas, discreet sine transform is used as self-orthogonalizing transform to address the eigen-spread problem. The simulation results are the evidence of significantly improvement in the convergence rate and mean squared error (MSE) performance of the proposed algorithm. View full abstract»

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  • Algorithms and hardware design of modern numeric overcurrent and distance relays

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (579 KB) |  | HTML iconHTML  

    There has been a significant change in design of protective relays over the past years, due to the advancement in microprocessor and signal processing technology. Due to the advancements in digital technology and decrease in digital hardware prices numeric relays are now available and being used for power system protection. This paper describes fundamental design for a numeric relay and presents algorithms to be used for different protection schemes i.e. overcurrent protection, distance protection, differential protection. View full abstract»

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  • Analysis of the induced EMF in permanent magnet brushless motors

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1135 KB) |  | HTML iconHTML  

    The performance of permanent magnet brushless DC motors depends on their winding and magnetic designs. The conductor distribution and flux density distribution profiles determine the shape of induced EMF waveform. The shape of the induced EMF of the machine can be used to predict its torque performance. This paper presents a new method to analyze the induced EMF of the permanent magnet brushless motors including the effect of fringing and leakage flux. The Fourier harmonic method is used to analyze the induced EMF. The induced EMF is constructed in time using the harmonics for few typical machine designs. View full abstract»

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  • Biomechanical bipedal model with asymmetrical reference trajectories for sit-to-stand task

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (699 KB) |  | HTML iconHTML  

    Human bipedal models behave symmetrically as well as asymmetrically depending upon nature of movement, task and orientation of the body. A bipedal model with full symmetry of limbs and movement is very redundant engineering design which has lots of unstable eigenvalues and poles. To avoid redundancy asymmetry is introduced which imposes coordination and controller design problem. In this paper, we are presenting a biomechanical bipedal model with 13 generalized coordinates of joint angles of right and left limbs in sagittal and frontal plane, a left foot translation. This model has no moment in right foot translation and asymmetrical reference trajectories in right and left limbs. An optimal controller design provides the feedback torque for stable sit-to-stand movement. Our results indicate the applicability of this model for stroke patients or subjects with paraplegic limbs. View full abstract»

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  • Capacity analysis for voice and queue management differences in IEEE 802.11 and 802.11e WLAN standards

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (595 KB) |  | HTML iconHTML  

    Voice over IP (VoIP) has become very popular in recent years. Different coding, error and compensations schemes have been developed to increase the number and quality of voice connections over IP networks. This research work is an investigative study to find out maximum number of possible voice calls supported by quality of service aware IEEE 802.11e and basic 802.11 WLAN standards. Apart from quantitative capacity analysis this paper provides simulation study of differences of queue management at medium access layer between IEEE 802.11 and 802.11e WLAN standards. View full abstract»

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  • Chaos control of voltage fluctuations in DC Arc Furnaces using time-delay feedback control

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (593 KB) |  | HTML iconHTML  

    The goal is to control a chaotic behavior of DC arc furnaces. The time-delay feedback control (TDFC) technique of such chaos will be presented. The system is found exponentially stable under the novel proposed control whilst the fast transient response is maintained. Such a physical restriction is also satisfied when the control signal has to be constructed. The performance is found satisfactory whilst the chaos behavior is also omitted. View full abstract»

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  • Comparative analysis of different distortion reduction techniques for parametric loudspeaker based on self-demodulation of amplitude modulated ultrasound waves

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (871 KB) |  | HTML iconHTML  

    A highly focused sound beam can be created from the nonlinear interaction of ultrasound waves by using a parametric loudspeaker. An audio signal is produced by the self-demodulation of amplitude modulated sound waves in air. Several preprocessing techniques have been discussed in previous literature to reduce distortion. A comparative analysis of these preprocessing techniques is presented in this paper. Some preceding preprocessing techniques rely on equalization and square-rooting. Newer techniques, instead of using only simple AM, have an additional AM signal with a carrier that is orthogonal to the original one. It will be clearly seen that the distortion of the modified AM is greatly reduced from the normal AM. Simulation results show the effectiveness of the preprocessing techniques. View full abstract»

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  • Comparison of interaction of GVD and SPM between normal and anomalous dispersion regimes of single mode fiber

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (685 KB) |  | HTML iconHTML  

    The quality of the optical pulse propagating through single mode fiber is degraded due to fiber loss, group velocity dispersion (GVD) and self phase modulation (SPM). We present and compare our results of the variation in peak power (and hence broadening or compression of the pulse) of a Gaussian pulse propagating through single mode fiber in normal versus anomalous dispersion regimes; both for lossless and lossy fibers. The effects of fiber loss, GVD and SPM are modeled using nonlinear Schrodinger equation (NLSE). We used split step Fourier method to solve NLSE numerically. The patterns of changes in peak power with the propagated distance are quite different in normal and anomalous regimes. Our results show that it is possible to either compress or obtain the input pulse almost in its original form at certain propagated distances in anomalous dispersion regime; while it is not possible in normal dispersion regime. View full abstract»

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  • Control of torque in switched reluctance motor

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (753 KB) |  | HTML iconHTML  

    Switched reluctance motor is gaining large interest of industry due to it mechanical simplicity, ruggedness behavior and low cost. On the other hand its advantages are over shadowed by need of intelligent control for its inherent issues like torque ripple, acoustic noise and high non linear characteristics. This paper focuses on torque ripple issue and its reduction through phase current control. Two quadrant and four quadrant chopper operation is discussed mathematically and simulated in Matlab, results aided with graphs are discussed to conclude which drive provides better control over phase currents. View full abstract»

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  • Decentralized Robust Control of a MIMO system using parametric & non-diagonal interaction uncertainty modeling

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (755 KB) |  | HTML iconHTML  

    This work describes the design of robust decentralized controllers for a multivariable system by considering the parametric uncertainty due to parametric variation and interaction uncertainty due to non-diagonal elements of a plant. First the plant is considered for uncertainty modeling. Then three methodologies are used to design decentralized Hinfin controllers and decentralized Hinfin fixed order decentralized controllers. The performances of these methodologies are compared for a highly coupled three tank system. The close loop system is analyzed for uncertainty, Hinfin norm reduction, Nominal Performance (NP), robust performance (RP), nominal stability (NS) and robust stability (RS). The system has achieved 100% RS and NS, and remarkable RP, NP, Hinfin norm reduction and time domain performance. View full abstract»

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  • Design & implementation of a standard gain horn antenna for optimized gain and radiation pattern using MathCAD & HFSS

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (977 KB) |  | HTML iconHTML  

    This paper is about the design and implementation of a standard gain horn antenna using MathCAD & High frequency structure simulator (HFSS) Software. The horn was designed by implementing a procedure in MathCAD. Simulation & optimization of the horn was carried out in HFSS based on finite element method (FEM). The reason to simulate the horn in HFSS is the fact to achieve optimum gain and equal radiation patterns in both E-plane & H-plane (pencil beam). Itpsilas also easy in HFSS to optimize the various dimensions of the horn for optimum results. After the simulation & optimization, the horn was manufactured and tested. The results of the finalized simulation and actually manufactured horn are very close to each other. View full abstract»

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  • Design of low switching loss PWM boost converter

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1125 KB) |  | HTML iconHTML  

    This paper presents an improved design of zero-current-switching PWM soft-commutation cell. The proposed converter features soft commutation of the active switches at zero current. It incorporates the most desirable properties of conventional PWM and soft-switching resonant techniques. Besides operating at constant frequency and with reduced commutation losses, the proposed converter has no additional current stresses. The principle of operation, theoretical analysis and simulation results of the proposed ZCS-PWM boost converter using Power MOSFETpsilas are presented to verify the performance of the proposed converter. View full abstract»

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  • Design, optimization and development of X-band microstrip patch antenna array for high gain, low sidelobes and impedance matching

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (844 KB) |  | HTML iconHTML  

    The objective was to design and fabricate a four element X-band microstrip array centered at 7.5 GHz which has high gain, low sidelobe levels and is simultaneously well matched to the source. The design starts with formulation in Matlabreg for single element patch antenna. The design was then simulated and optimized in Agilentpsilas advanced design system (ADS) for high gain by making the patch resonating at the same center frequency but with larger dimensions. An array of four such elements was designed in ADS Momentum. Inter element spacing and feed line was optimized for good impedance matching, low sidelobes and high gain. By using method of moments (MoM) the effect of mutual coupling among the elements was taken into account. The array was manufactured, tested in anechoic chamber and results were compared with simulations. View full abstract»

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  • Developing a tagset for Pashto part of speech tagging

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    While building a machine translation system, the embedded part-of-speech (POS) tagger deserves special attention. The ever first tagset discussed here is created in accordance with the EAGLES guidelines. These guidelines were written for the languages of European Union. They can also be applied to Pashto language. This paper presents the creation process of Pashto tagset, which helps in the development of a POS tagger. View full abstract»

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  • Distribution system monitoring using remote point simplex differential event data transmission at real time tokens

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (477 KB) |  | HTML iconHTML  

    A remote point simplex data acquisition system has been proposed to monitor a distribution system from its grid station. Data is concentrated at the remote end then transmitted to central receiver for processing. A facility is incorporated to record the currents of all transformers associated to a distribution system. Data received can be used for on-line monitoring of the distribution system, analysis of system losses and planning to decrease line losses. This data can be further be used for optimal planning of distribution system and distribution system expansion. This can provide improvement in the distribution system performance and significant benefits to the utility. The proposed token networking of the remote end transmitters and differential event recording technique reduce the data records. View full abstract»

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  • Efficient utilization of solar energy for domestic applications

    Page(s): 1 - 3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB) |  | HTML iconHTML  

    Shortage of energy is dangerously affecting the economic growth of the developing countries. Oil, gas and coal reserves are being depleted rapidly and are affecting the environment. Embargo and safety requirements limit the development of nuclear energy. Renewable energy resources need to be embedded with the conventional generation. A lot has been said and done on solar energy. However emphasis has been on the conversion to electricity using photovoltaic cells. In the present work, it is proposed that efficient use of solar energy would be to utilize it for direct heating and cooling. Solar chillers based on solar heating coupled with gas firing are proposed for urban houses. Solar pumps for irrigation in the rural areas should be used. This would reduce the demand of electricity hungry air conditioners and diesel hungry tube wells. View full abstract»

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