An advanced reconfigurable controller improved by a multiple model architecture is proposed as a tool to achieve fault tolerance in complex nonlinear systems. The most complete adaptive critic design, Globalized Dual ...
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An advanced reconfigurable controller improved by a multiple model architecture is proposed as a tool to achieve fault tolerance in complex nonlinear systems. The most complete adaptive critic design, Globalized Dual Heuristic Programming (GDHP), constitutes a highly flexible nonlinear adaptive controller responsible for the generation of new control solutions for novel plant dynamics introduced by unknown faults. Working on a higher hierarchical level, the proposed supervisor makes use of two quality indexes to perform fault detection, identification and isolation based on the knowledge stored in a dynamic model bank. In the event of abrupt known faults, such knowledge is then used to greatly reduce the reconfiguration time of the GDHP controller. The synergy of the proposed supervisor and GDHP goes beyond, as solutions designed by the controller to previously unknown faults are autonomously added to the model bank. The fine interrelations among the algorithm's subsystems are illustrated in a rich numerical simulation of a MIMO nonlinear system subject to different fault scenarios.
This paper presents a novel technique to linearize frequency multipliers for use with modulated signals. Using amplitude and phase mapping functions, a modulated signal may be translated to an integer multiple of the ...
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This paper presents a novel technique to linearize frequency multipliers for use with modulated signals. Using amplitude and phase mapping functions, a modulated signal may be translated to an integer multiple of the carrier frequency with minimal distortion. To validate this technique, a sch.ttky-diode frequency tripler was built to transmit digital signals at 2.46 GHz with an 820 MHz input carrier frequency. Measured results show that with an IS-95B input signal, the digital predistorter achieved 26 dB of improvement in the Adjacent Channel Power Ratio (ACPR) at 2.46 GHz. Its output Error Vector Magnitude (EVM) was 13% with predistortion, whereas it was near 100% without predistortion. Additionally, an adaptive digital predistorter was designed, and simulation showed a 40 dB improvement in IMD with 4-tone signal input.
In general, the hardware memory consistency model in a multiprocessor system is not identical to the memory model at the programming language level. Consequently, the programming language memory model must be mapped o...
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In general, the hardware memory consistency model in a multiprocessor system is not identical to the memory model at the programming language level. Consequently, the programming language memory model must be mapped onto the hardware memory model. Memory fence instructions can be inserted by the compiler where needed to accomplish this mapping. We have developed and implemented several fence insertion and optimization algorithms in our Pensieve compiler project. We present the different fence insertion optimization techniques that were used in this system to guarantee sequential consistency at the language level, and compare them using performance data. Our techniques target two hardware relaxed memory consistency models provided by SMPs based on IBM Power 3 and Intel Pentium 4. Our fence insertion optimization shows up to 17.2% and 32.7% performance improvement on average, with the IBM PowerPC and Intel Pentium 4 (Xeon) multiprocessors respectively.
This paper examines the problem of modelling and resynthesis of voiced song with the goal of improving the subjective performance quality. A set of methods is introduced based on the sinusoidal model for speech which ...
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This paper examines the problem of modelling and resynthesis of voiced song with the goal of improving the subjective performance quality. A set of methods is introduced based on the sinusoidal model for speech which enables precise modification of spectral characteristics as well as vibrato structure while maintaining the original speech quality and naturalness of the voice. Spectral characteristics are modified by modelling the formant structure with a set of asymmetric generalized Gaussians. Subjective tests were conducted which show that the proposed methods are effective in providing high quality modifications to vocal characteristics.
A slow frequency-hopping (FH) spread-spectrum (SS) system with trellis-coded interleaved continuous phase modulation (CPM) is proposed, where the phase is continuous during each hop interval. The proposed system provi...
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A slow frequency-hopping (FH) spread-spectrum (SS) system with trellis-coded interleaved continuous phase modulation (CPM) is proposed, where the phase is continuous during each hop interval. The proposed system provides power- and bandwidth-efficient anti-jam capability in the presence of partial-band noise jamming. The proposed receivers use coherent or non-coherent iterative demodulation and decoding along with jammer state information. Furthermore, an iterative jamming state estimation technique is proposed to provide robust anti-jam performance.
The increasing amount of music being stored in digital formats calls for increasingly more creative methods for music information retrieval. One subset of music retrieval methods relies on storing a melody in a pitch ...
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The increasing amount of music being stored in digital formats calls for increasingly more creative methods for music information retrieval. One subset of music retrieval methods relies on storing a melody in a pitch contour representation. Most often, this contour information is generated either from symbolic format (MIDI) or from raw audio after a pitch transcription step. In this paper, we propose a method of extracting pitch contour information from musical audio without an intermediate transcription step by combining a musically-tuned constant Q transform with cross-correlation. When tested on a database of 520 monophonic music recordings, our method generates pitch contours from raw audio data with up to 98% accuracy.
The current paper proposes an improved reproduction algorithm that can produce a realistic image of a real scene based on the spectral distribution of light and objects, as perceived by human eyes. First, a backward r...
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The current paper proposes an improved reproduction algorithm that can produce a realistic image of a real scene based on the spectral distribution of light and objects, as perceived by human eyes. First, a backward ray tracing method is used where the spectral distribution of objects and illuminants is used to represent the physical characteristics in the real world. Next, an improved shading model is proposed based on applying Bouguer-Beer's law to consider the optical absorptive property of transparent objects. Finally, instead of a constant ambient light term, a new ambient light term is defined that considers the diffuse reflection of neighboring objects.
The progress in information and communication technology (ICT), sensors and embedded computing is discussed. Experimental applications that characterize the demand placed on emerging computational techniques and infra...
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The progress in information and communication technology (ICT), sensors and embedded computing is discussed. Experimental applications that characterize the demand placed on emerging computational techniques and infrastructure are described. Experimental environments provide an environment that can be used to naturally understand events. Employing new techniques to deal with live spatiotemporal data streams will enable ICT to address many real-world problems. The application of ICT to problems in mainstream human society produces new scientific and business challenges.
This paper addresses the problem of robust control design for a single-phase uninterruptible power supply by means of state feedback. Sufficient conditions are given for the existence of a robust stabilizing control g...
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This paper addresses the problem of robust control design for a single-phase uninterruptible power supply by means of state feedback. Sufficient conditions are given for the existence of a robust stabilizing control gain that assures: a) the closed-loop system pole location inside a circle on the left-hand of the complex plane if the load is considered as an uncertain time-invariant or slow time-varying parameter;b) at least the stability of the closed-loop system if the load is considered as an arbitrary time-varying parameter. The robust control conditions are formulated in terms of a set of linear matrix inequalities easily solved using specialized softwares. Design examples and simulation results illustrate the method proposed.
A methodology for designing reliable RF circuits is proposed. A model to predict hot carrier and soft breakdown effects on CMOS device parameters in RF circuits is developed. Hot carrier and soft breakdown effects are...
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A methodology for designing reliable RF circuits is proposed. A model to predict hot carrier and soft breakdown effects on CMOS device parameters in RF circuits is developed. Hot carrier and soft breakdown effects are evaluated experimentally with 0.16 μm CMOS technology. Device stress measurement and SpectreRF simulation are conducted to evaluate the impact of hot carrier and soft breakdown effects on RF circuits such as low noise amplifier and voltage-controlled oscillator performance. Two design techniques to build reliable RF circuits are proposed and verified.
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