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Mohammad Saleh Tavazoei - One of the best experts on this subject based on the ideXlab platform.

  • Criteria for Response monotonicity preserving in approximation of fractional order systems
    IEEE CAA Journal of Automatica Sinica, 2016
    Co-Authors: Mohammad Saleh Tavazoei
    Abstract:

    In approximation of fractional order systems, a significant objective is to preserve the important properties of the original system. The monotonicity of time Frequency Responses is one of these properties whose preservation is of great importance in approximation process. Considering this importance, the issues of monotonicity preservation of the step Response and monotonicity preservation of the Magnitude-Frequency Response are independently investigated in this paper. In these investigations, some conditions on approximating filters of fractional operators are found to guarantee the preservation of step Magnitude-Frequency Response monotonicity in approximation process. These conditions are also simplified in some special cases. In addition, numerical simulation results are presented to show the usefulness of the obtained conditions.

  • Magnitude–Frequency Responses of fractional order systems: properties and subsequent results
    IET Control Theory & Applications, 2016
    Co-Authors: Mohammad Saleh Tavazoei
    Abstract:

    This study deals with the properties of Magnitude–Frequency Responses in fractional order systems. Using Phragmen–Lindelof theorem in complex analysis, it is shown that the supremum of the Magnitude–Frequency Response of a fractional system with a commensurate order less than one cannot be greater than that of its integer order bounded-input, bounded-output stable counterpart. Further results are also obtained on Magnitude–Frequency Response of stable/unstable fractional order systems. Moreover, it is found that the supremum (infimum) of the Magnitude-scaling Frequency of the family of fractional order systems having a fixed structure and different orders in the range (0, 2) is a piecewise logarithmically convex (concave) function of the scaling Frequency. On the basis of the properties of Magnitude–Frequency Responses in fractional order systems, some sample consequent results which are useful in analysis of fractional order circuits and systems are derived. These results are validated by various numerical examples.

  • Algebraic conditions for monotonicity of Magnitude-Frequency Responses in all-pole fractional order systems
    IET Control Theory & Applications, 2014
    Co-Authors: Mohammad Saleh Tavazoei
    Abstract:

    This study deals with the investigation of the Magnitude-Frequency Responses of all-pole fractional order systems in the viewpoint of extrema existence in these Responses. In this investigation, a sufficient algebraic condition, two necessary algebraic conditions, and a necessary and sufficient algebraic condition are obtained to guarantee the non-existence of extrema in the Magnitude-Frequency Response of all-pole fractional order systems. Some examples are presented to show the effectiveness of the results of the paper.

B. Nowrouzian - One of the best experts on this subject based on the ideXlab platform.

  • Theory and design of LDI lattice digital and switched-capacitor filters
    IEE Proceedings G Circuits Devices and Systems, 1992
    Co-Authors: B. Nowrouzian
    Abstract:

    The paper presents a new method for the exact design and synthesis of lossless discrete-integrator (LDI) lattice digital and switched-capacitor (SC) filters. In the proposed design method, the entire digital and SC filter synthesis is performed directly in the discrete-time z-domain without any recourse to the concept of a continuous-time analogue prototype reference filter. Two LDI lattic e digital filter structures are proposed, one of which employs a Foster-type and the other a Cauer-type (leapfrog) configuration. Both of these structures require at most n+1 digital multipliers and n+1 unit delays, where n represents the order of the transfer function to be realised. Similarly, the corresponding LDI lattice SC filters require at most n+2 operational amplifiers (single- or double-ended). A practical example is given to illustrate the design method and to compare the hardware requirement and the Magnitude-Frequency Response sensitivity in the passband of the LDI lattice digital and SC filters with those of the corresponding bilinear LDI ladder digital and SC filters. It is shown that the proposed lattice filters exhibit superior sensitivity features despite their low hardware requirements.

  • Design of general-order shaping transfer functions for Bode-type variable-amplitude digital equalizers
    1998 Midwest Symposium on Circuits and Systems (Cat. No. 98CB36268), 1
    Co-Authors: A.t.c. Fuller, B. Nowrouzian
    Abstract:

    In the design of Bode-type variable-amplitude digital equalizers, the constituent shaping transfer function is usually required to satisfy certain prescribed Magnitude-Frequency Response characteristics. These characteristics include: a "passband" with a prespecified maximum gain, a "stopband" with unity, gain, and a single prespecified gain at the passband edge(s). This paper presents a novel approximation technique for the design of general-order shaping transfer functions with maximally flat or equiripple lowpass, highpass, or bandpass Magnitude-Frequency Response characteristics. This is achieved by first deriving a corresponding normalized prototype lowpass shaping transfer function, and then by applying a lowpass-to-lowpass, lowpass-to-highpass, or lowpass-to-bandpass Frequency transformation to obtain the desired (denormalized) shaping transfer function. These shaping transfer functions can be employed in the design of variable-amplitude digital equalizers having Magnitude-Frequency Responses with sharp transition bands and reduced inter-band interference in the corresponding digital graphic equalizers.

  • ISCAS (5) - A novel approach to the exact design of first- and second-order Bode-type variable-amplitude bilinear-LDI switched-capacitor equalizers
    2005 IEEE International Symposium on Circuits and Systems, 1
    Co-Authors: B. Nowrouzian, Arthur T. G. Fuller, M.n.s. Swamy
    Abstract:

    This paper presents a novel approach to the exact design of first- and second-order Bode-type variable-amplitude (VA) bilinear-LDI switched-capacitor (SC) equalizers. The proposed design approach is based on the realization of the VA equalizer transfer function as the transfer function of a Frequency-independent two-terminal-pair SC network at its input terminal-pair when its output terminal-pair is terminated in a (Frequency-dependent) SC one-terminal-pair realization of the dual of the equalizer shaping impedance function. The resulting first-order equalizers produce fan-shaped lowpass or highpass Magnitude-Frequency Responses, while the resulting second-order equalizer produces a bump-shaped (bandpass) Magnitude-Frequency Response. The salient feature of the proposed SC equalizers is that only a single variable capacitor is required to control the fan amplitude in the first-order equalizers and the bump amplitude in the second-order equalizer. Moreover, these equalizers remain BIBO stable for all possible values of the variable capacitor. In addition, they exhibit the important practical feature that a geometrically symmetric change in the value of the variable capacitor causes a corresponding arithmetically symmetric change in the logarithmic Magnitude-Frequency Response of the VA equalizer. An application example is given to illustrate the main results.

  • Design of FIR digital filters using weighted peak-constrained least-squares optimization
    Engineering Solutions for the Next Millennium. 1999 IEEE Canadian Conference on Electrical and Computer Engineering (Cat. No.99TH8411), 1
    Co-Authors: B. Nowrouzian
    Abstract:

    This paper is concerned with the application of the peak constrained least-squares (PCLS) optimization to the design of finite-impulse-Response (FIR) digital filters. The salient feature of the PCLS optimization is that it permits the simultaneous min-max (MM) and least-squares (LS) optimization in a single run, leading to the design of digital filters exhibiting equal-ripple passband and minimum energy stopband Magnitude-Frequency Response characteristics. The PCLS optimization proves to be particularly effective for the design of FIR digital filters having a large number of coefficients (both for symmetric as well as asymmetric digital filters), typically taking a small number of iterations to converge to the final optimal digital filter.

  • ISCAS (1) - Design of arbitrary-order minimal operational-amplifier BIBO stable Bode-type variable-amplitude active-RC equalizers
    2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512), 1
    Co-Authors: B. Nowrouzian, Arthur T. G. Fuller, M.n.s. Swamy
    Abstract:

    This paper presents a new technique for the exact design and minimal operational-amplifier realization of arbitrary-order bounded-input-bounded-output (BIBO) stable Bode-type variable-amplitude (VA) active-RC equalizers. This technique is based on the realization of the VA equalizer transfer function directly as the voltage transfer function from port 1 to port 2 of an active-R three-port network when its port 3 is terminated in the active-RC realization of the corresponding (positive-real) shaping impedance function. The salient feature of the resulting VA active-RC equalizers is that they permit the continuous variation of the equalizer transfer function from the corresponding shaping transfer function to its inverse through the use of one single (positive) variable resistor only. In addition, they permit arithmetically symmetric changes in the logarithmic Magnitude-Frequency Response of the equalizer through geometrically symmetric changes in the value of the constituent variable resistor. An application example is given to illustrate the main results.

Christina Schlumbohm - One of the best experts on this subject based on the ideXlab platform.

  • Neurally Mediated Airway Constriction in Human and Other Species: A Comparative Study Using Precision-Cut Lung Slices (PCLS)
    2016
    Co-Authors: Annette D. Rieg, Sophie Seehase, Jan Spillner, Alberto Perez-bouza, Till Braunschweig, Thomas Schroeder, Marc Bernau, Verena Lambermont, Christina Schlumbohm, Katherina Sewald
    Abstract:

    The peripheral airway innervation of the lower respiratory tract of mammals is not completely functionally characterized. Recently, we have shown in rats that precision-cut lung slices (PCLS) respond to electric field stimulation (EFS) and provide a useful model to study neural airway Responses in distal airways. Since airway Responses are known to exhibit considerable species differences, here we examined the neural Responses of PCLS prepared from mice, rats, guinea pigs, sheep, marmosets and humans. Peripheral neurons were activated either by EFS or by capsaicin. Bronchoconstriction in Response to identical EFS conditions varied between species in Magnitude. Frequency Response curves did reveal further species-dependent differences of nerve activation in PCLS. Atropine antagonized the EFS-induced bronchoconstriction in human, guinea pig, sheep, rat and marmoset PCLS, showing cholinergic Responses. Capsaicin (10 mM) caused bronchoconstriction in human (4 from 7) and guinea pig lungs only, indicating excitatory non-adrenergic non-cholinergic Responses (eNANC). However, this effect was notably smaller in human responder (3067.1%) than in guinea pig (7965.1%) PCLS. The transient receptor potential (TRP) channel blockers SKF96365 and ruthenium red antagonized airway contractions after exposure to EFS or capsaicin in guinea pigs. In conclusion, the different species show distinct patterns of nerve-mediate

  • Neurally mediated airway constriction in human and other species: a comparative study using precision-cut lung slices (PCLS).
    PloS one, 2012
    Co-Authors: Marco Schlepütz, Annette D. Rieg, Sophie Seehase, Jan Spillner, Alberto Perez-bouza, Till Braunschweig, Thomas Schroeder, Marc Bernau, Verena Lambermont, Christina Schlumbohm
    Abstract:

    The peripheral airway innervation of the lower respiratory tract of mammals is not completely functionally characterized. Recently, we have shown in rats that precision-cut lung slices (PCLS) respond to electric field stimulation (EFS) and provide a useful model to study neural airway Responses in distal airways. Since airway Responses are known to exhibit considerable species differences, here we examined the neural Responses of PCLS prepared from mice, rats, guinea pigs, sheep, marmosets and humans. Peripheral neurons were activated either by EFS or by capsaicin. Bronchoconstriction in Response to identical EFS conditions varied between species in Magnitude. Frequency Response curves did reveal further species-dependent differences of nerve activation in PCLS. Atropine antagonized the EFS-induced bronchoconstriction in human, guinea pig, sheep, rat and marmoset PCLS, showing cholinergic Responses. Capsaicin (10 µM) caused bronchoconstriction in human (4 from 7) and guinea pig lungs only, indicating excitatory non-adrenergic non-cholinergic Responses (eNANC). However, this effect was notably smaller in human responder (30±7.1%) than in guinea pig (79±5.1%) PCLS. The transient receptor potential (TRP) channel blockers SKF96365 and ruthenium red antagonized airway contractions after exposure to EFS or capsaicin in guinea pigs. In conclusion, the different species show distinct patterns of nerve-mediated bronchoconstriction. In the most common experimental animals, i.e. in mice and rats, these Responses differ considerably from those in humans. On the other hand, guinea pig and marmoset monkey mimic human Responses well and may thus serve as clinically relevant models to study neural airway Responses.

Arthur T. G. Fuller - One of the best experts on this subject based on the ideXlab platform.

  • Design of first- and second-order bode-type wave-digital variable-amplitude equalizers
    Canadian Journal of Electrical and Computer Engineering, 1998
    Co-Authors: Arthur T. G. Fuller, Behrouz Nowrouzian
    Abstract:

    This paper presents a synthesis technique for the design of first- and second-order Bode-type wave-digital (WD) variable-amplitude equalizers. The proposed first-order equalizer consists of one unit-delay and two digital multipliers and produces a fan-shaped Magnitude-Frequency Response, while the proposed second-order equalizer consists of two unit-delays and three digital multipliers and produces a bump-shaped Magnitude-Frequency Response. The salient feature of the resulting WD equalizers is that only a single digital variable multiplier is required to control the fan amplitude in the first-order equalizer and the bump amplitude in the second-orderequalizer without changing their other important Magnitude-Frequency Response characteristics (e.g., the cut-off Frequency in the fan equalizer and the centre Frequency and quality factor in the bump equalizer). Moreover, these equalizers remain bounded-input bounded-output (BIBO) stable (under infinite-precision arithmetic) for all possible values of the variable multiplier. In addition, they exhibit the important practical feature that a geometrically symmetric change in the value of the variable multiplier causes a corresponding arithmetically symmetric change in the logarithmic Magnitude-Frequency Response of the equalizer. Application examples are given to illustrate the main results.

  • ISCAS (5) - A novel approach to the exact design of first- and second-order Bode-type variable-amplitude bilinear-LDI switched-capacitor equalizers
    2005 IEEE International Symposium on Circuits and Systems, 1
    Co-Authors: B. Nowrouzian, Arthur T. G. Fuller, M.n.s. Swamy
    Abstract:

    This paper presents a novel approach to the exact design of first- and second-order Bode-type variable-amplitude (VA) bilinear-LDI switched-capacitor (SC) equalizers. The proposed design approach is based on the realization of the VA equalizer transfer function as the transfer function of a Frequency-independent two-terminal-pair SC network at its input terminal-pair when its output terminal-pair is terminated in a (Frequency-dependent) SC one-terminal-pair realization of the dual of the equalizer shaping impedance function. The resulting first-order equalizers produce fan-shaped lowpass or highpass Magnitude-Frequency Responses, while the resulting second-order equalizer produces a bump-shaped (bandpass) Magnitude-Frequency Response. The salient feature of the proposed SC equalizers is that only a single variable capacitor is required to control the fan amplitude in the first-order equalizers and the bump amplitude in the second-order equalizer. Moreover, these equalizers remain BIBO stable for all possible values of the variable capacitor. In addition, they exhibit the important practical feature that a geometrically symmetric change in the value of the variable capacitor causes a corresponding arithmetically symmetric change in the logarithmic Magnitude-Frequency Response of the VA equalizer. An application example is given to illustrate the main results.

  • ISCAS (1) - Design of arbitrary-order minimal operational-amplifier BIBO stable Bode-type variable-amplitude active-RC equalizers
    2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512), 1
    Co-Authors: B. Nowrouzian, Arthur T. G. Fuller, M.n.s. Swamy
    Abstract:

    This paper presents a new technique for the exact design and minimal operational-amplifier realization of arbitrary-order bounded-input-bounded-output (BIBO) stable Bode-type variable-amplitude (VA) active-RC equalizers. This technique is based on the realization of the VA equalizer transfer function directly as the voltage transfer function from port 1 to port 2 of an active-R three-port network when its port 3 is terminated in the active-RC realization of the corresponding (positive-real) shaping impedance function. The salient feature of the resulting VA active-RC equalizers is that they permit the continuous variation of the equalizer transfer function from the corresponding shaping transfer function to its inverse through the use of one single (positive) variable resistor only. In addition, they permit arithmetically symmetric changes in the logarithmic Magnitude-Frequency Response of the equalizer through geometrically symmetric changes in the value of the constituent variable resistor. An application example is given to illustrate the main results.

  • ISCAS (1) - A novel approach to the design and synthesis of general-order Bode-type variable-amplitude active-RC equalizers
    Proceedings of the 2003 International Symposium on Circuits and Systems 2003. ISCAS '03., 1
    Co-Authors: B. Nowrouzian, Arthur T. G. Fuller
    Abstract:

    This paper presents a novel approach to the exact design and synthesis of general-order active-RC Bode-type variable-amplitude (VA) equalizers. The proposed design approach is based on, (a) the realization of the VA equalizer transfer function as the input-pair transmittance of a two-pair signal-flow network having the shaping transfer function as its output-pair terminating transmittance, and (b) the realization of the output-pair terminating transmittance in terms of a singly-terminated positive-real impedance function. The resulting VA active-RC equalizers permit the continuous variation of the equalizer transfer function from the shaping transfer function to its inverse through the use of a single positive variable resistor only.. In addition, they exhibit the important practical feature that a geometrically symmetric change in the value of the variable resistor causes a corresponding arithmetically symmetric change in the logarithmic Magnitude-Frequency Response of the equalizer. An application example is given to illustrate the main results.

  • ISCAS (2) - A novel approach to the design of higher-order Bode-type variable-amplitude wave-digital equalizers
    ISCAS 2001. The 2001 IEEE International Symposium on Circuits and Systems (Cat. No.01CH37196), 1
    Co-Authors: B. Nowrouzian, Arthur T. G. Fuller
    Abstract:

    This paper presents a novel approach to the design of higher-order Bode-type variable-amplitude (VA) wave-digital (WD) equalizers. This approach is based on, (a) the derivation of a corresponding continuous-time VA equalizer transfer function from a set of high-level system design specifications, (b) the development of an analog prototype reference network suitable for a corresponding WD equalizer realization, and (c) the transformation of the analog prototype reference network to the desired VA WD equalizer through the use of the bilinear Frequency transformation. The salient feature of the resulting VA WD equalizers is that they permit the continuous variation of the WD equalizer transfer function from a shaping transfer function to its inverse while requiring one single variable digital multiplier only. In addition, they exhibit the important practical feature that a geometrically symmetric change in the value of the variable digital multiplier causes a corresponding arithmetically symmetric change in the logarithmic Magnitude-Frequency Response of the WD equalizer. An application example is given to illustrate the main results.

Xinhai Zou - One of the best experts on this subject based on the ideXlab platform.

  • Hyperfine Intrinsic Magnitude and Phase Response Measurement of Optical Filters Based on Electro-Optical Harmonics Heterodyne and Wiener–Lee Transformation
    Journal of Lightwave Technology, 2019
    Co-Authors: Xinhai Zou, Shangjian Zhang, Zhiyao Zhang, Shuang Liu, Dejun Chen, Yong Liu
    Abstract:

    An electro-optical heterodyne scheme is proposed and demonstrated for Magnitude- and phase-Frequency Response measurement of optical filters based on harmonics heterodyne and Wiener–Lee transformation. The method consists of an acousto-optic Frequency shifter and a phase modulator located in a Frequency-shifted heterodyne interferometer. The minimum phase-Frequency Response is simultaneously extracted from the measured Magnitude–Frequency Response with the help of Kramers–Kronig relations and the Wiener–Lee transformation. As compared with the single-sideband-based or double-sideband-based methods, our method eliminates small-signal assumption and features an immunity to undesired spurious sidebands, enabling harmonic sideband sweeping with even-folded measuring Frequency range. Prior to the conventional Frequency-shifted heterodyne methods, the method enables simultaneous extraction of intrinsic Magnitude and phase Frequency Responses for most optical filters by introducing the Wiener–Lee transformation. A phase-shifted fiber Bragg grating is measured for extracting the Frequency Responses in the proof-of-concept experiment with the Frequency resolution up to 50 kHz and Frequency range of 80 GHz by using a Frequency-swept modulation of 20 GHz.

  • Wideband and High-Resolution Measurement of Magnitude-Frequency Response for Optical Filters Based on Fixed-Low-Frequency Heterodyne Detection
    IEEE Photonics Journal, 2017
    Co-Authors: Xinhai Zou, Shangjian Zhang, Heng Wang, Zhiyao Zhang, Yali Zhang, Shuang Liu, Yong Liu
    Abstract:

    A high-resolution electrical method is proposed for Magnitude-Frequency Response measurement of optical filters based on fixed-low-Frequency heterodyne detection. The method consists of an acousto-optic Frequency shifter and two phase modulators located in a Mach–Zehnder interferometer architecture. The modulation sidebands in the test arm pass through the optical filter under test and heterodyne with the Frequency-shifted modulation sidebands in the reference arm, which allows extracting the Magnitude-Frequency Response of the optical filter from two fixed-Frequency heterodyne electrical components in the low-Frequency region. In the demonstration, the Magnitude-Frequency Response of a phase-shifted fiber Bragg grating (FBG) is experimentally extracted from low-Frequency heterodyne signals fixed at 69.5 and 70.5 MHz, respectively, with hyperfine resolution up to 50 kHz and wide Frequency range of 140 GHz. The proposed electrical method enables wideband Magnitude-Frequency Response measurement for both band-pass and band-stop filters with low-Frequency detection. Moreover, it features not only the immunity to modulation nonlinearity but the bidirection sweeping with doubled measurement range as well. Besides, the method only needs to receive and analyze low-Frequency signals at two fixed frequencies, which largely speeds up the swept Frequency measurement.

  • a self reference and high resolution method for measuring the Magnitude Frequency Response of optical filters
    Wireless and Optical Communications Conference, 2016
    Co-Authors: Xinhai Zou, Shangjian Zhang, Heng Wang, Yali Zhang
    Abstract:

    A self-reference method for measuring the Magnitude Frequency Response of optical filters is proposed based on nested heterodyne interferometer, which enables high-resolution measurement in the electrical domain with doubled measuring Frequency range.

  • WOCC - A self-reference and high-resolution method for measuring the Magnitude Frequency Response of optical filters
    2016 25th Wireless and Optical Communication Conference (WOCC), 2016
    Co-Authors: Xinhai Zou, Shangjian Zhang, Heng Wang, Yali Zhang, Yongliu
    Abstract:

    A self-reference method for measuring the Magnitude Frequency Response of optical filters is proposed based on nested heterodyne interferometer, which enables high-resolution measurement in the electrical domain with doubled measuring Frequency range.

  • Hyperfine Magnitude Response measurement for optical filters based on low-Frequency detection
    2016 IEEE Photonics Conference (IPC), 2016
    Co-Authors: Shangjian Zhang, Xinhai Zou, Heng Wang, Yali Zhang, Yong Liu, Chong Zhang, John E. Bowers
    Abstract:

    An electrical method for characterizing optical filters is proposed and demonstrated based on low-Frequency detection, which enables Magnitude Frequency Response measurement with hyperfine resolution up to 50 kHz and doubled measuring Frequency range in the electrical domain.