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TENCON 2003. Conference on Convergent Technologies for the Asia-Pacific Region

Date 15-17 Oct. 2003

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  • Fast convergence LMS adaptive filters employing fuzzy partial updates

    Publication Year: 2003 , Page(s): 1334 - 1337 Vol.4
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (369 KB)  

    This paper presents a method to improve the performance of reduced calculation adaptive filters. We use the sequential partial update method to achieve low computation complexity. Furthermore, we include the variable step-size approach to aim last convergence. The variable step size approach is based on a fuzzy method to determine the appropriate step-size on each iteration step. By using the proposed method, the adaptive filter converges faster while pretending the steady state error as the previously proposed reduced calculation adaptive filler. The instantaneous step size is determined from the present square of the error signal to produce sudden changing. Additional rule or conditions are included to prevent the adaptive algorithm to become unstable. Simulation results are presented to compare the performance of the new approach, the fixed step-size LMS algorithm and sequential partial update LMS (S-LMS) algorithms. View full abstract»

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  • Line harmonics reduction using neural based controller for shunt active filters

    Publication Year: 2003 , Page(s): 1554 - 1557 Vol.4
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (318 KB) |  | HTML iconHTML  

    Harmonic distortion is a form of electrical noise. It is a superposition of signals, which are of multiples of fundamental frequency. Proliferation of large power electronic systems results in increased harmonic distortion. Harmonic distortion results in reduction of power quality and system stability. This paper presents neural based proportional integral (PI) control applicable for active power filters for single-phase systems, which are comprised of multiple nonlinear loads. The active filter is based on a single-phase inverter with four controllable switches, a standard H-bridge inverter. The AC side of the inverter is connected in parallel with the other nonlinear loads through a filter inductance. The DC side of the inverter is connected to a filter capacitor. The neural Pl controller is used to shape the current through the filter inductor such that the line current is in phase with and of the same shape as the input voltage. Simulation results prove that the injected harmonics are greatly reduced and system efficiency and power factor are improved. View full abstract»

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  • Static off state and conduction state charge imbalance in the superjunction power MOSFET

    Publication Year: 2003 , Page(s): 1455 - 1459 Vol.4
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB) |  | HTML iconHTML  

    The superjunction (SJ) layer for 600 V is analytically designed for perfect charge balance and compared with SJ MOSFET, where the channel region creates charge imbalance due to unsymmetrical drift layer. We estimated this imbalance created due to the channel region with the help simulation. In order to simulate the SJ MOSFET with physical limitations of the fabrication technology, we have deliberately introduced the imbalance in SJ drift layer by varying the doping density of p pillar and then of n drift layer up to 10% respectively. The effect of this imbalance on the off state and on the on state breakdown voltage of the device investigated in detail with the help of simulation. View full abstract»

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  • A fuzzy-neural approach to electricity load and spot-price forecasting in a deregulated electricity market

    Publication Year: 2003 , Page(s): 1479 - 1482 Vol.4
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (387 KB) |  | HTML iconHTML  

    Accurate short term load forecasting is crucial to the efficient and economic operation of modem electrical power systems. With the recent effort by many governments in the development of open and deregulated power markets, research in forecasting methods is getting renewed attention. Although long term and short term electric load forecasting has been of interest to the practicing engineers and researchers for many years, spot-price prediction is a relatively new research area. This paper examines the use of a neural-fuzzy inference method for the prediction of 24 hourly load and spot price for the next day. Publicly available data of the electricity market of the state of New South Wales, Australia is used in a case study. View full abstract»

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  • Information congestion

    Publication Year: 2003 , Page(s): 1595 - 1599 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (474 KB) |  | HTML iconHTML  

    This paper talks about information congestion in an enterprise. The various reasons for information congestion, strategies and guidelines like portals, content management systems, personalization and framework based solution to control information congestion in an enterprise. By keeping a futuristic view, this paper also demonstrates how business process modeling based on emerging standards like intelligent agents can address information congestion. View full abstract»

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  • Allpass lattice structure based second order digital IIR notch filter for removing DC and very low frequencies

    Publication Year: 2003 , Page(s): 1384 - 1385 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (255 KB) |  | HTML iconHTML  

    In this paper, an allpass lattice structure based second order notch filter with notch at DC is designed. The filter perfectly removes the dc and the specified very low frequencies. It can be designed for a very sharp transition band thereby eliminating frequencies close to DC. The filter is simple to implement and the number of multipliers required is equal to one. For the purpose of illustration, the filter is designed to meet a cutoff frequency of 1 Hz for a sampling frequency 800 Hz and applied to remove the baseline wander in ECG signals. View full abstract»

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  • Object-based affine motion estimation

    Publication Year: 2003 , Page(s): 1343 - 1347 Vol.4
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (526 KB) |  | HTML iconHTML  

    Motion estimation and compensation form a major part in any video coding scheme. The video coding standard adopted for multimedia applications is the MPEG-4 wherein object-based motion estimation comes into play. However, MPEG-4 uses conventional motion estimation technique that can detect only pure translational motion along the image plane and fails to consider any complex motion that arises due to rotation, zooming, etc. An efficient way of detecting complex motion is by using the affine motion model. In this paper, we develop a scheme for estimating affine motion of object suitable for MPEG-4 video coding thereby achieving high quality. Simulation results demonstrate the efficiency of the proposed scheme in comparison to conventional object-based motion estimation techniques. View full abstract»

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  • Effect of wave function modulation on high frequency response characteristics of GaAs/AlAs quantum wells

    Publication Year: 2003 , Page(s): 1308 - 1310 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (313 KB)  

    The effect of wave function modulation on the high frequency response of GaAs/AlAs quantum wells with several thin barrier layers being inserted inside the well is studied. Carrier scattering by longitudinal optic phonons, deformation potential acoustic phonons and background-ionized impurities are considered. The wave function modulation induced inside the quantum wells is found to reduce the intersubband scattering strength and considerably enhance the ac mobility normalized by the dc mobility. The variation of the normalized ac mobility with the frequency of the applied field is found to be fairly constant up to certain frequency beyond which it drops down. View full abstract»

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  • An adaptive fuzzy filter system for smoothing noisy images

    Publication Year: 2003 , Page(s): 1614 - 1617 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (481 KB) |  | HTML iconHTML  

    This paper presents an adaptive fuzzy filter system that combines the outputs of several filters at any time. It is observed that each objective function associated with a filter yields differing capability in the filtering operation. Hence, all the objective functions are divided into 2 types: multiplicative type (Pi) and summation type (Sigma). In this paper, we present several filter combinations and show that each filter combination called hybrid filter, which consists of filters from both types, is effective in reducing Gaussian type and impulse noises. The outputs of the filters are combined depending upon the value of pixel compatibility, which is computed from the gray-level differences between the central pixel and its neighbours. View full abstract»

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  • Robust timing synchronization for OFDM based wireless LAN system

    Publication Year: 2003 , Page(s): 1558 - 1561 Vol.4
    Cited by:  Papers (10)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (379 KB) |  | HTML iconHTML  

    In this paper, a robust a and efficient frame detection and symbol timing synchronization technique suitable for IEEE 802.11a wireless LAN system is proposed. The proposed method does frame detection using a threshold comparison mechanism and performs orthogonal frequency division multiplexing (OFDM) symbol boundary detection using correlation techniques. This algorithm is a novel combination of self and cross correlation information to achieve symbol timing synchronization. The proposed algorithm can robustly detect the symbol boundary even under low SNRs, high frequency offset, and multipath. View full abstract»

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  • A parameterisable VHDL model of an avionics data bus

    Publication Year: 2003 , Page(s): 1604 - 1608 Vol.4
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (429 KB) |  | HTML iconHTML  

    This paper presents a behavioural model of a serial data bus of an avionics mission system. Such models are essential not only for the design and synthesis of the bus, they are also very important for determining the behaviour and performance of the bus prior to implementation. Various important aspects of the associated protocol standard have been captured in the model including three important message types. One important feature of the model is the parameterisation of key system parameters. This makes the model very flexible for simulating different model sizes and payloads with ease. Simulations have been carried out for different model sixes and payloads. The results obtained indicate the validity of the model. Furthermore, data about bus performance have also been obtained from simulations. View full abstract»

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  • In vivo assessment of osteoporosis in women by impulse response technique

    Publication Year: 2003 , Page(s): 1395 - 1398 Vol.4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (399 KB) |  | HTML iconHTML  

    Osteoporosis in women is increasingly being recognized as an important health issue. The dynamic characteristics of bone which provides quantitative information concerning the mechanical properties of" the bone along with measurement of bone mineral density (GMO) can help in the early detection and better diagnosis of osteoporosis. In the present study quantitative assessment of osteoporosis is carried out by impulse response test on the tibial bone of 42 women subjects (age = 44.5±11.6 years). The stress waves arc generated in the tibial bone by the impact of impulse force hammer arc monitored by accelerometers, and are analyzed in the frequency domain. The natural frequency of stress wave signal is significantly decreased in osteopenia and osteoporosis subjects indicating decrease in mechanical strength of the bone and bone mineral mass. Regression analysis shows a moderately significant negative correlation between natural frequency and age. The natural frequency of stress wave signal shows a good correlation with calcaneus stiffness index (SI) and T-score measured by quantitative ultrasound technique. View full abstract»

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  • Incorporating dynamic behavior in SMTP

    Publication Year: 2003 , Page(s): 1293 - 1297 Vol.4
    Cited by:  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB) |  | HTML iconHTML  

    The all-pervasive and ubiquitous email is essentially static in nature. An email once sent remains as such and the sender no longer has any control over it. There is no mechanism available for changing any portion of the email that is obsolete: instead a new email has to be sent, thus cluttering the receiver's mailbox. In this paper, the authors have proposed an extension to SMTP that would let the sender of an email safely replace and in some cases, remove emails sent by him. The underlying motivation and a concise, yet reasonably comprehensive implementation mechanism has been described here. View full abstract»

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  • Data-aided timing offset estimation for frequency selective fading channels

    Publication Year: 2003 , Page(s): 1530 - 1534 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB) |  | HTML iconHTML  

    In this paper, a novel algorithm for timing offset estimation is proposed for GSM and GPRS handsets, especially for multipath channels with large delay-spread. The timing offset leads to errors in the channel response estimation with a consequent increase in the overall bit error rate (BER). Thus, timing synchronization and tracking are crucial for satisfactory functioning of burst mode mobile communication receivers. In the proposed technique, minimum residual error energy concept is used for capturing multi-path delay profile and correlation based method is used for fine timing offset. Some simulation results are provided to illustrate the effectiveness of the proposed method. View full abstract»

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  • Speech coding a new approach

    Publication Year: 2003 , Page(s): 1483 - 1485 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (395 KB) |  | HTML iconHTML  

    Text-to-speech synthesis, based on ESNOLA, uses signal dictionary having raw sound signals representing parts of phonemes. State-phase analysis for detection of voiced region along with detection of pitch also may be used for extraction of the most appropriate signal elements automatically from continuous speech in real time. The signal elements at the voiced zone are perceptual-pitch-periods. These signal are coded by simply inserting one information byte at the beginning of each element. The decoding is done using the information bit. The intervening signals are regenerated by linear estimation from the two perceptual-pitch-periods. This coding induces a ten-fold information reduction without significant loss of naturalness. View full abstract»

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  • VHDL based design of an FDWT processor

    Publication Year: 2003 , Page(s): 1609 - 1613 Vol.4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (449 KB) |  | HTML iconHTML  

    This paper presents the hardware design of a forward discrete wavelet transform (FDWT) processor using VHDL. The design is based on the JPEG2000 standard and utilises the lossless features of FDWT. This is a reversible algorithm, which means there is no loss of information while compressing and transmitting the image information. This paper presents the hardware architecture of the processor as well ns the design of its constituent components in VHDL. The architecture does not comprise any hardware multiplier unit and therefore suitable for development of high-performance image processors. Simulations show that one block of an image can be transformed up to 5 levels of computation using this FDWT processor. View full abstract»

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  • Architecture of a software radio system based on cluster of workstations

    Publication Year: 2003 , Page(s): 1439 - 1444 Vol.4
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB) |  | HTML iconHTML  

    Conventional software radio architectures cannot perform signal processing using application level software or have limited capability. To solve these problems, this paper proposes a new architecture that can perform signal processing using application level software on cluster of workstations. This paper introduces key technologies from RF to baseband. Especially, detail designs are given for core technologies of PCI card and parallel processing. Based on these principles, wireless voice communications for four standards are realized on the system. Theory and practice prove that this is a scalable, more ideal software radio and is a promising one with potential. View full abstract»

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  • Hybrid reconstruction in Bayesian domain

    Publication Year: 2003 , Page(s): 1424 - 1428 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (451 KB) |  | HTML iconHTML  

    Image reconstruction in Bayesian framework is far more advantageous over other reconstruction methods like convolution back projection, weighted least square method and maximum likelihood estimation. The power of Bayesian estimation ties in its ability to incorporate the prior distribution knowledge, enabling better reconstruction. Proper specification of clique potentials in Bayesian estimation plays a crucial role in the reconstruction process by favors the presence of desired characteristics in the image lattice like nearest neighbor interactions and homogeneity. Homogenous Markov random fields have been successfully used for modeling such interactions. Though reconstructions produced by such models are far more efficient, they often require large iterations for producing an approximate reconstruction. To deal with this problem, we have extended the Bayesian estimation in order to support sharp reconstruction. We propose to use sharp potential in Bayesian estimation once an approximate reconstruction is available using homogenous potentials in Bayesian domain The advantage of the proposed potential is its ability to recognize correlated nearest neighbors. The proposed reconstruction is a hybrid of both smooth and sharp potential in Bayesian framework and hence it is termed as hybrid reconstruction. Simulated experiments have shown that the proposed hybrid estimation method produces superior and sharp reconstruction as compared to the reconstruction produced by other Bayesian estimation methods. View full abstract»

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  • Accurate rotor position estimation for switched reluctance motor using ANFIS

    Publication Year: 2003 , Page(s): 1493 - 1497 Vol.4
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB) |  | HTML iconHTML  

    An efficient operation of the switched reluctance motor (SRM) can be achieved only by proper estimation of the rotor position. The rotor position information in switched reluctance motor (SRM) drives is essential for determining the switching instants for proper control of speed, torque and torque pulsations. Several sensorless control methods of rotor position estimation are available for SRM drives. Among them the flux-current method is mostly used to estimate the rotor position. In this paper, the rotor position estimation at standstill and during running conditions of a 6/4-pole SRM involving flux current method using adaptive network fuzzy inference system (ANFIS) is presented. View full abstract»

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  • Application of wavelet multiresolution analysis for classification of faults on transmission lines

    Publication Year: 2003 , Page(s): 1464 - 1469 Vol.4
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (542 KB) |  | HTML iconHTML  

    This paper presents a new method for classification of faults based on wavelet multiresolution analysis (MRA). Daubechies eight (D-8) wavelet transforms of the three phase currents on a transmission line fed from both ends are used. The summations of the 3rd level output of MRA detail signals of current in each phase extracted from the original signals are used as the criterion for the analysis. The effects of fault distance, fault inception angle and fault impedance are also examined. Extensive simulations are carried out to generate time domain input signal using EMTP (Microtran) on a 230 kV, 200 km long line fed from both ends and simulation results show that the proposed method is a simple, effective and robust method suitable for high impedance faults also. View full abstract»

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  • Autoregressive (AR) based power spectral analysis of heart rate time series signal (HRTS signal)

    Publication Year: 2003 , Page(s): 1391 - 1394 Vol.4
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (373 KB) |  | HTML iconHTML  

    Heart rate time series (HRTS) signal has been studied using auto-regressive (AR) based power spectrum. Twenty-five controls and twenty-five MI patients were taken for this study. From HRTS signal, 480 epochs of 32 seconds overlapping by a 31 seconds are extracted. Power spectrum is computed epoch-by-epoch and frequency domain HRTS signal parameters arc derived. These parameters show the discrimination between the controls and MI patients. The statistical results arc shown in the table below. From this study it can be concluded that the analysis of HRTS signal may lead to detection of MI in advance. View full abstract»

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  • Design optimization of inverter fed 3-phase squirrel cage induction motor

    Publication Year: 2003 , Page(s): 1303 - 1307 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (459 KB) |  | HTML iconHTML  

    Static inverter fed induction motor drive is an important competitor in the field of variable speed drives. Design optimization of a six-stepped three-phase inverter fed squirrel cage induction motor for minimum cost and maximum frequency operation is presented in this paper. Additional winding loss, core loss, stray loss and torque pulsations produced by harmonic voltages over a frequency-range that influence the design parameters are considered as constraints. In addition many important constraints at minimum frequency such as no-load power factor, locked rotor current and at maximum frequency pullout torque etc., are imposed to satisfy the performance characteristics. Nonlinear programming technique (NLP) employing Powell's unconstrained optimization method together with Zangwill's exterior penalty function formulation is applied to a mathematical model of an inverter fed 3-phase squirrel-cage induction motor with 11 design variables and a number of performance constraints. The optimal solution by this method efficiently proved the design optimization procedure adopted in this paper satisfying the constraints to predict the machine performance. View full abstract»

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  • Event based commanding

    Publication Year: 2003 , Page(s): 1288 - 1292 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    This paper presents the software system titled "event based commanding" developed for one of the ground automated mode of telecommanding operations for Indian geo-stationary satellites. Any satellite needs health monitoring, analyzing and controlling with respect to the requirement. Monitoring, analyzing and controlling is done by controller/operator as per the defined and necessary directives. As the number of satellites to be maintained is increasing, automation of ground control and commanding is required for responding quickly for spacecraft specific critical anomalies to avoid human made mistakes and also to reduce the required manpower. Event based commanding has been developed as part of overall automation of ground operations. The present software system provides the facility for defining, monitoring and executing events. An event consists of a logical expression with spacecraft health parameters and corresponding monitoring values and also the list of commands to be sent on the Occurrence of the event continuously for the given number of samples/times. This mode of commanding has been implemented for many of the geo-stationary satellites like INSAT-2C. INSAT-3B, INSATJC, KALPANA-I and INSAT-3A. The software in operation at MCF, Hassan has handled quite a few critical anomalies for INSAT-2C and INSAT-3B, by automatically taking over command control to uplink essential commands. The software has also been efficiently handling certain routine operations like thermal management of satellites. View full abstract»

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  • Integrated scheduling of hard real-time and multimedia tasks

    Publication Year: 2003 , Page(s): 1618 - 1622 Vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (513 KB) |  | HTML iconHTML  

    In this paper, we develop a tool for carrying out acceptance tests in a multiprocessor system, for workloads that include both sporadic hard tasks with specified resource requirements, and multimedia tasks with firm (m, k) guarantees. The tool is a two-level scheduler. The higher-level server planner generates server arrangements for the multimedia server, such that it can meet the (m, k) firm guarantees, and can execute optional task instances as well, while the lower-level feasibility checker determines the schedulability of the sporadic tasks under the specified server arrangement. The two levels iterate until schedulability is determined. The tool has been validated through simulation. View full abstract»

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  • Design of an embedded receiver for satellite-based real time voice and data messaging for efficient disaster management

    Publication Year: 2003 , Page(s): 1414 - 1418 Vol.4
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (410 KB) |  | HTML iconHTML  

    Disaster management is combination of various technological, infrastructural and administrative activities and communities have already recognized the need to improve capability for adopting and using real time communication systems for the benefit of all sectors of the community specially for the purpose of dissemination of warning messages predicting impending disaster. There is no denying the fact that satellite communication is a very important organ for modern telecommunication system in view of certain advantages ,viz., it is always on service, very large coverage and accessibility from any corner of the globe. Further, satellites are not prone to disaster and provide real time communication. Satellite-based real time voice and data messaging would be of immense help to people for dissemination of warning and related co-ordination activities. This paper describes design of a mission critical satellite receiver for real time satellite-based voice and data messaging system suitable for disaster management solutions. The receiver is used for disseminating the cyclone warning message in local languages to remote coastal villages of India from regional weather office using satellite backbone. Cyclone warning messages are meant for some specific remote location and broadcast warning message contains coded headers followed by voice or data files. The satellite receiver has been designed to demodulate L-band signal and decode the packetized data from the demodulated output. The receiver will play the audio only if its embedded algorithm matches the decoded data with its own identification number. View full abstract»

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