The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform

Gregoire Sissoko - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Incident Illumination Angle on Capacitance of a Silicon Solar Cell under Frequency Modulation
    Research Journal of Applied Sciences Engineering and Technology, 2013
    Co-Authors: Amary Thiam, Martial Zoungrana, H. Ly Diallo, Amadou Diao, N. Thiam, S. Gueye, M. M. Deme, M. Sarr, Gregoire Sissoko
    Abstract:

    The aim of this study is to present a theoretical study of a silicon solar cell under frequency modulation. Solving the continuity equation lead to the analytical expressions of the minority carriers' density, the photocurrent and the photo voltage. The photocurrent and the photo voltage are plotted versus the modulation frequency in a semi-logarithmic scale for various incidence angles; the dynamic impedance of the solar cell is then derived. The Nyquist Diagram of the impedance is plotted for various incidence angles, leading to the determination of the series and parallel resistances. The determination of the diffusion capacitance is also made based on the Bode Diagram of the solar cell impedance. The influence of the modulation frequency and the incidence angle on the diffusion capacitance and the series and parallel resistances is then exhibited.

  • three dimensional study of a polycrystalline silicon solar cell the influence of the applied magnetic field on the electrical parameters
    Semiconductor Science and Technology, 2011
    Co-Authors: A Dieng, I Zerbo, M Wade, A S Maiga, Gregoire Sissoko
    Abstract:

    In this paper, we present a theoretical 3D study of a polycrystalline silicon solar cell in frequency modulation under polychromatic illumination and applied magnetic field. The influence of the applied magnetic field on the diode current density, Jd, and both electric power–photovoltage and photocurrent–photovoltage characteristics are discussed. The Nyquist Diagram permitted us to determine the electrical parameters such as the series resistance Rs and parallel equivalent resistance Rp of a polycrystalline silicon solar cell. The Bode Diagram is then used to calculate the cut-off frequency, capacitance C and inductance L. It has been shown that, under a magnetic field, the solar cell behavior is like that of a low-pass filter.

Baorong Hou - One of the best experts on this subject based on the ideXlab platform.

  • impedimetric immunosensor doped with reduced graphene sheets fabricated by controllable electrodeposition for the non labelled detection of bacteria
    Biosensors and Bioelectronics, 2011
    Co-Authors: Yi Wan, Dun Zhang, Zhifeng Lin, Yi Wang, Baorong Hou
    Abstract:

    A facile, sensitive and reliable impedimetric immunosensor doped with reduced graphene sheets (RGSs) and combined with a controllable electrodeposition technique was developed for the selective detection of marine pathogenic sulphate-reducing bacteria (SRB). The morphology of RGSs and the electrochemical properties of RGSs-doped chitosan (CS) nanocomposite film were investigated by atomic force microscopy. Fourier transform infrared spectroscopy, and cyclic voltammetry (CV). Electrochemical impedance spectroscopy and CV were used to verify the stepwise assembly of the sensor system. Faradic impedance spectroscopy for charge transfer for the redox probe Fe(CN)(6)(3-/4-) was done to determine SRB concentrations. The diameter of the Nyquist Diagram that is equal to the charge-transfer resistance (R(ct)) increased with increasing SRB concentration. A linear relationship between Rct and SRB concentration was obtained in the SRB concentration range of 1.8 x 10(1) to 1.8 x 10(7) cfu/ml. The impedimetric biosensor gave a distinct response to SRB, but had no obvious response to Vibrio angillarum. It showed a high selectivity for the detection of the pathogen. Based on a combination of the biocompatibility of CS and good electrical conductivity of RGSs, a nanocomposite film with novel architecture was used to immobilize biological and chemical targets and to develop a new type of biosensor. (C) 2010 Elsevier B.V. All rights reserved.

  • monitoring microbial populations of sulfate reducing bacteria using an impedimetric immunosensor based on agglutination assay
    Talanta, 2009
    Co-Authors: Yi Wan, Dun Zhang, Baorong Hou
    Abstract:

    An impedimetric immunosensor was fabricated for rapid and non-labeled detection of sulfate-reducing bacteria, Desulforibrio caledoiensis (SRB) by immobilizing lectin-Concanavalin A using an agglutination assay. The immobilization of lectin was conducted using amine coupling on the surface of a gold (Au) electrode assembled with 11-Mercaptounclecanoic acid. Electrochemical impedance spectroscopy (EIS) was used to verify the stepwise assembly of the sensor system. The work conditions of the impedimetric immunosensor, such as pH of the buffer solutions and the incubation time of lectin, were optimized. Faradic impedance spectra for charge transfer for the redox probe Fe(CN)(6)(3-/4-) were measured to determine SRB concentrations. The diameter of the Nyquist Diagram that is equal to the charge-transfer resistance (RI) increased with increasing SRB concentration. A linear relationship between R(ct) and SRB concentration was obtained in SRB concentration range of 1.8 to 1.8 x 10(7) cfu/ml. The variation of the SRB population during the growth process was also monitored using the impedimetric immunosensor. This approach has great potential for simple, low-cost. and time-saving monitoring of microbial populations. (C) 2009 Elsevier B.V. All rights reserved.

Alireza Karimi - One of the best experts on this subject based on the ideXlab platform.

  • Fixed-orderH∞ControllerDesign forNonparametricModels byConvexOptimization 1
    2016
    Co-Authors: Alireza Karimi, Gorka Galdos
    Abstract:

    A new approach for robust fixed-order H ∞ controller design by convex optimization is proposed. Linear time-invariant single-input single-output systems represented by nonparametric models in the frequency domain are considered. It is shown that the H ∞ robust performance condition can be represented by a set of linear or convex constraints with respect to the parameters of a linearly parameterized controller in the Nyquist Diagram. Multimodel and frequency-domain uncertainty can be considered straightforwardly in the proposed approach. The proposed method is compared with the standard H ∞ control problem by a simulation example on an unstable system.

  • h gain scheduled controller design for rejection of time varying narrow band disturbances applied to a benchmark problem
    European Journal of Control, 2013
    Co-Authors: Alireza Karimi, Zlatko Emedi
    Abstract:

    A new method for H-infinity gain-scheduled controller design by convex optimization is proposed that uses only frequency-domain data. The method is based on loop shaping in the Nyquist Diagram with constraints on the weighted infinity-norm of closed-loop transfer functions. This method is applied to a benchmark for adaptive rejection of multiple narrow-band disturbances. First, it is shown that a robust controller can be designed for the rejection of a sinusoidal disturbance with known frequency. The disturbance model is fixed in the controller, based on the internal model principle, and the other controller parameters are computed by convex optimization to meet the constraints on the infinity-norm of sensitivity functions. It is shown next that a gain scheduled-controller can be computed for a finite set of disturbance frequencies by convex optimization. An adaptation algorithm is used to estimate the disturbance frequency which adjusts the parameters of the internal model in the controller. The simulation and experimental results show the good performance of the proposed control system.

  • rst controller design by convex optimization using frequency domain data
    IFAC Proceedings Volumes, 2011
    Co-Authors: Gorka Galdos, Alireza Karimi, R Longchamp
    Abstract:

    A new robust fixed-order RST controller design approach by convex optimization is proposed in this paper. Only frequency-domain data are considered in the approach for linear time-invariant single-input single-output systems. It is shown that performance specifications given as the infinity norm of the weighted sensitivity functions can be represented as convex constraints in the Nyquist Diagram. One of the advantage of the proposed method is that it can deal directly with multi-model uncertainty. Moreover, a solution to a real industrial problem is given showing the effectiveness of the method.

  • robust controller design by linear programming with application to a double axis positioning system
    Control Engineering Practice, 2007
    Co-Authors: Alireza Karimi, Marc Kunze, R Longchamp
    Abstract:

    Abstract A linear programming approach is proposed to tune fixed-order linearly parameterized controllers for stable LTI plants. The method is based on the shaping of the open-loop transfer function in the Nyquist Diagram. A lower bound on the crossover frequency and a new linear stability margin which guarantees lower bounds for the classical robustness margins are defined. Two optimization problems are proposed and solved by linear programming. In the first one the robustness margin is maximized for a given lower bound on the crossover frequency, whereas in the second one the closed-loop performance in terms of the load disturbance rejection is optimized with constraints on the new stability margin. The method can directly consider multi-model as well as frequency-domain uncertainties. An application to a high-precision double-axis positioning system illustrates the effectiveness of the proposed approach.

Josep M Guerrero - One of the best experts on this subject based on the ideXlab platform.

  • multirate resonant controllers for grid connected inverters with harmonic compensation function
    IEEE Transactions on Industrial Electronics, 2019
    Co-Authors: Chuan Xie, Xin Zhao, Jianxiao Zou, Josep M Guerrero
    Abstract:

    Resonant controller (RSC) is one of the most popular approaches for ac current/voltage control due to the high performance of zero steady-state tracking error. However, it suffers from heavy computational burden issue when multiple RSCs are demanded to control multiple harmonics. To alleviate this issue, a down-sampled multirate RSCs (MRRSCs) scheme is proposed for controlling power inverters, e.g., grid-connected inverters and active power filters. The proposed control scheme is composed of an inner control loop with a fast sampling rate, which is identical to the switching frequency, and an array of paralleled MRRSCs-based external control loop with a reduced sampling rate. With the reduced sample rate, the MRRSCs can be executed alternatively in the dq -frame, such that the computational burden can be significantly reduced per cycle. Moreover, to reinforce the wide frequency adaptability of the MRRSC, its central resonant frequency is online updated according to the output of the phase-locked loop. In the paper, the equivalent single-rate closed-loop model of the overall system is developed, based on which the controller parameters are designed employing the Nyquist Diagram and root locus. Finally, experiments are performed on a grid-connected inverter to validate the superiority of the proposed scheme.

Yi Wan - One of the best experts on this subject based on the ideXlab platform.

  • impedimetric immunosensor doped with reduced graphene sheets fabricated by controllable electrodeposition for the non labelled detection of bacteria
    Biosensors and Bioelectronics, 2011
    Co-Authors: Yi Wan, Dun Zhang, Zhifeng Lin, Yi Wang, Baorong Hou
    Abstract:

    A facile, sensitive and reliable impedimetric immunosensor doped with reduced graphene sheets (RGSs) and combined with a controllable electrodeposition technique was developed for the selective detection of marine pathogenic sulphate-reducing bacteria (SRB). The morphology of RGSs and the electrochemical properties of RGSs-doped chitosan (CS) nanocomposite film were investigated by atomic force microscopy. Fourier transform infrared spectroscopy, and cyclic voltammetry (CV). Electrochemical impedance spectroscopy and CV were used to verify the stepwise assembly of the sensor system. Faradic impedance spectroscopy for charge transfer for the redox probe Fe(CN)(6)(3-/4-) was done to determine SRB concentrations. The diameter of the Nyquist Diagram that is equal to the charge-transfer resistance (R(ct)) increased with increasing SRB concentration. A linear relationship between Rct and SRB concentration was obtained in the SRB concentration range of 1.8 x 10(1) to 1.8 x 10(7) cfu/ml. The impedimetric biosensor gave a distinct response to SRB, but had no obvious response to Vibrio angillarum. It showed a high selectivity for the detection of the pathogen. Based on a combination of the biocompatibility of CS and good electrical conductivity of RGSs, a nanocomposite film with novel architecture was used to immobilize biological and chemical targets and to develop a new type of biosensor. (C) 2010 Elsevier B.V. All rights reserved.

  • monitoring microbial populations of sulfate reducing bacteria using an impedimetric immunosensor based on agglutination assay
    Talanta, 2009
    Co-Authors: Yi Wan, Dun Zhang, Baorong Hou
    Abstract:

    An impedimetric immunosensor was fabricated for rapid and non-labeled detection of sulfate-reducing bacteria, Desulforibrio caledoiensis (SRB) by immobilizing lectin-Concanavalin A using an agglutination assay. The immobilization of lectin was conducted using amine coupling on the surface of a gold (Au) electrode assembled with 11-Mercaptounclecanoic acid. Electrochemical impedance spectroscopy (EIS) was used to verify the stepwise assembly of the sensor system. The work conditions of the impedimetric immunosensor, such as pH of the buffer solutions and the incubation time of lectin, were optimized. Faradic impedance spectra for charge transfer for the redox probe Fe(CN)(6)(3-/4-) were measured to determine SRB concentrations. The diameter of the Nyquist Diagram that is equal to the charge-transfer resistance (RI) increased with increasing SRB concentration. A linear relationship between R(ct) and SRB concentration was obtained in SRB concentration range of 1.8 to 1.8 x 10(7) cfu/ml. The variation of the SRB population during the growth process was also monitored using the impedimetric immunosensor. This approach has great potential for simple, low-cost. and time-saving monitoring of microbial populations. (C) 2009 Elsevier B.V. All rights reserved.