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Tobias M Bockers - One of the best experts on this subject based on the ideXlab platform.

  • thiel fixation preserves the non linear Load deformation characteristic of spinal motion segments but increases their flexibility
    Journal of The Mechanical Behavior of Biomedical Materials, 2011
    Co-Authors: Hansjoachim Wilke, Karin Werner, Kim Haussler, Michael Reinehr, Tobias M Bockers
    Abstract:

    Abstract Human cadaveric specimens are recommended as the best option for in-vitro tests. However, fresh human spine specimens are often difficult to obtain. Further problems are the potential risk of infection and they can only be used over a limited test period. Therefore, the use of embalmed specimens is often discussed. The most common method is formalin fixation. However, this type of embalming can result in failure, because the biomechanical properties of the tissue is partially influenced. In recent years the development of the new method, the fixation according to Thiel, could provide an alternative to fresh or formalin-fixed specimens. The aim of the present study is to compare the biomechanical properties between fresh and Thiel-fixed spine specimens, and to compare the data to previous data of a test with formalin fixation. For the study, six L1–L2 spinal segments from 16-week-old calves were biomechanically tested. The parameters, range of motion and neutral zone, were determined in flexion/extension, right/left lateral bending and left/right axial rotation. The results showed that the specimens kept their Non-Linear Load–deformation-characteristic after Thiel fixation. The range of motion of Thiel-fixed specimens increased relative to the unembalmed state by approximately 22% in flexion–extension, 23% in lateral bending ( p 0.05 ) and 45% in axial rotation ( p 0.05 ). In conclusion, the results still suggest a preference for fresh cadaveric spine specimens for quantitative biomechanical in-vitro testing, because they provide the best physiological conditions. However, for preliminary tests, which may only be used for orientation, embalmed specimens using the Thiel fixation method might serve as an alternative. Compared to formalin-fixated specimens which become approximately 5 times stiffer and completely lose their Non-Linear Load–deformation-characteristic, as found in a previous study; the Thiel fixation maintains the Non-Linear Load–deformation-characteristic but increases the range of motion.

Lieven Vandevelde - One of the best experts on this subject based on the ideXlab platform.

Kamalakanta Mahapatra - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive-Fuzzy Controller Based Shunt Active Filter for Power Line Conditioners
    TELKOMNIKA (Telecommunication Computing Electronics and Control), 2011
    Co-Authors: Karuppanan Pitchaivijaya, Kamalakanta Mahapatra
    Abstract:

    This paper presents a novel Fuzzy Logic Controller (FLC) in conjunction with Phase Locked Loop (PLL) based shunt active filter for Power Line Conditioners (PLCs) to improve the power quality in the distribution system. The active filter is implemented with current controlled Voltage Source Inverter (VSI) for compensating current harmonics and reactive power at the point of common coupling. The VSI gate control switching pulses are derived from proposed Adaptive-Fuzzy-Hysteresis Current Controller (HCC) and this method calculates the hysteresis bandwidth effectively using fuzzy logic.  The bandwidth can be adjusted based on compensation current variation, which is used to optimize the required switching frequency and improves active filter substantially. These shunt active power filter system is investigated and verified under steady and transient-state with Non-Linear Load conditions. This shunt active filter is in compliance with IEEE 519 and IEC 61000-3 recommended harmonic standards.

  • pll with fuzzy logic controller based shunt active power filter for harmonic and reactive power compensation
    India International Conference on Power Electronics 2010 (IICPE2010), 2011
    Co-Authors: P Karuppanan, Kamalakanta Mahapatra
    Abstract:

    This paper presents a novel fuzzy logic controller in conjunction with phase locked loop synchronization based shunt Active Power Filter (APF) for harmonics and reactive power compensation in the distribution grid due to the Non-Linear Loads. The Mamdani-type fuzzy logic is adpted and this controller is linguistic description, so it does not require a mathematical calculations. The active power filter is implemented with current controlled voltage source inverter (VSI) and is connected at the point of common coupling for compensating current harmonics by injecting equal but opposite harmonic components. The desired reference current(s) are extracted using FLC with PLL-algorithm and this method maintains the dc-side capacitor voltage of the inverter nearly constant. The VSI gate switching signals are derived from adaptive-hysteresis current controller. The adaptive-hysteresis controller changes the bandwidth based on instantaneous compensation current variation; it is used to optimize the required switching frequency. The shunt APF system is investigated and the performances parameters are verified under different Non-Linear Load conditions.

Bhim Singh - One of the best experts on this subject based on the ideXlab platform.

  • control of 3 leg vsc based 3 phase 4 wire dstatcom using modified instantaneous symmetrical component theory
    International Journal of Automation and Power Engineering, 2013
    Co-Authors: Sunil Kumar, Bhim Singh
    Abstract:

    This paper deals with a 3‐leg VSC (Voltage Source Converter) with a zigzag transformer as a DSTATCOM (Distribution Static Compensator) for Load compensation in 3‐phase 4‐ wire distribution system using ISCT (Instantaneous Symmetrical Component Theory) based control algorithm which is modified for the voltage regulation and used with indirect current control technique. The DSTATCOM is controlled to compensate the reactive power, harmonics currents, the neutral current and balance the unbalanced Loads in the distribution system. Simulations are performed for the various Load conditions such as a reactive linear Load, an unbalanced Load and a non‐linear Load in PFC (Power Factor Correction) as well as in ZVR (Zero Voltage Regulation) modes in MATLAB environment using SIMULINK and SimPowerSystem toolbox. Extensive tests have been performed on a developed prototype of DSTATCOM to validate the control algorithm.

  • digital signal processor implementation and performance evaluation of split capacitor four leg and three h bridge based three phase four wire shunt active filters
    Iet Power Electronics, 2011
    Co-Authors: Vinod Khadkikar, Ambrish Chandra, Bhim Singh
    Abstract:

    In this paper a comprehensive study on the three-phase four-wire (3P4W) shunt active power filter (APF) is carried out on the basis of three system configurations. These three two-level voltage source inverter topologies are compared for 3P4W shunt APF, namely, split capacitor (2C), four-leg (4L) and three single-phase H-bridges (3HB). The performance of all three topologies, under an unbalanced Non-Linear Load condition, is evaluated with a detailed digital signal processor (DSP)-based experimental investigation. The steady-state as well as dynamic performance of APF is studied to compensate for current harmonics, reactive power, current unbalance and neutral current. The advantages and limitations offered by each of the topologies are also discussed in brief.

  • control of 4 leg vsc based dstatcom using modified instantaneous symmetrical component theory
    International Conference on Pervasive Services, 2009
    Co-Authors: Sunil Kumar, Bhim Singh
    Abstract:

    In this paper, a 4-leg VSC (voltage source converter) based DSTATCOM (Distribution Static Compensator) is used for the Load compensation and neutral current compensation in 3-phase 4-wire distribution system. For extracting the reference source currents, Instantaneous Symmetrical Component Theory (ISCT) based control algorithm is modified for voltage regulation and used with indirect current control technique for controlling the DSTATCOM currents. The DSTATCOM is controlled for power factor correction and voltage regulation at PCC (point of common coupling). Simulations are performed for various Load conditions such as a reactive linear Load, an unbalanced Load and a Non-Linear Load in Power Factor Correction (PFC) mode and in Zero Voltage Regulation (ZVR) mode in MATLAB environment using SIMULINK and Sim Power System (SPS) toolbox.

Naimish Zaveri - One of the best experts on this subject based on the ideXlab platform.

  • Comparison of control strategies for DSTATCOM in three-phase, four-wire distribution system for power quality improvement under various source voltage and Load conditions
    International Journal of Electrical Power & Energy Systems, 2012
    Co-Authors: Tejas Zaveri, Bhavesh R. Bhalja, Naimish Zaveri
    Abstract:

    This paper presents comparison of three different control strategies to generate reference current components for Distribution Static Compensator (DSTATCOM). Reference currents are tracked by a three-phase voltage source converter in a hysteresis band control scheme. These methods are instantaneous reactive power (IRP) theory, symmetrical component (SC) theory and an improved instantaneous active and reactive current component (IARCC) theory. The performance of three methods has been evaluated under various source voltage and Load conditions with new IEEE Standard 1459 power definitions. A comparative study of their performance in terms of rms value of source current, Total Harmonic Distortion (THD), supply power factor and compensator ratings is also presented. A three-phase, four-wire distribution system supplying linear as well as Non-Linear Load is considered for simulation study which is carried out using MATLAB/SIMULINK software. Under balanced and sinusoidal source voltage conditions, all three control strategies similar performance while an improved IARCC theory outperforms, particularly, under unbalanced and distorted source voltage conditions.