The Experts below are selected from a list of 90909 Experts worldwide ranked by ideXlab platform
Bijan Shirinzadeh - One of the best experts on this subject based on the ideXlab platform.
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robust adaptive constrained motion tracking control of piezo actuated flexure based mechanisms for micro nano manipulation
IEEE Transactions on Industrial Electronics, 2011Co-Authors: Hwee Choo Liaw, Bijan ShirinzadehAbstract:This paper presents a robust adaptive constrained motion tracking control methodology for piezo-actuated flexure-based micro/nano manipulation mechanisms. This unique control approach is established for the tracking of desired motion trajectories in a constrained environment exhibiting some degree of uncertain stiffness. The control methodology is also formulated to accommodate not only the parametric uncertainties and unknown force Conversion Function, but also nonlinearities including the hysteresis effect and external disturbances in the motion systems. In this paper, the equations for the dynamic modeling of a flexure-hinged four-bar micro/nano manipulation mechanism operating in a constrained environment are established. A lumped parameter dynamic model that combines the piezoelectric actuator and the micro/nano manipulation mechanism is developed for the formulation of the control methodology. Stability analysis of the proposed closed-loop system is conducted and the convergence of the motion tracking errors is proven theoretically. Furthermore, precise motion tracking ability in following a desired motion trajectory is demonstrated in the experimental study. An important advantage of this control approach is that it does not require the exact values for the system parameters and the force Conversion Function in the physical realization. This proposed constrained motion tracking control methodology is very useful for applications demanding high-precision motion tracking with force sensing and feedback.
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robust generalised impedance control of piezo actuated flexure based four bar mechanisms for micro nano manipulation
Sensors and Actuators A-physical, 2008Co-Authors: Hwee Choo Liaw, Bijan ShirinzadehAbstract:This paper presents a novel robust generalised impedance control methodology for piezo-actuated flexure-based four-bar micro/nano manipulation mechanisms. This control approach is proposed for compliant manipulation in which desired motion and force trajectories are controlled to achieve a specified generalised impedance. The control methodology is also formulated to accommodate not only the parametric uncertainties and unknown force Conversion Function, but also non-linearities including the hysteresis effect and external disturbances in the motion systems. In this paper, the equations for dynamic modelling of a flexure-hinged four-bar micro/nano mechanism making contact with its environment are established. A lumped parameter dynamic model that combines the piezoelectric actuator and the micro/nano mechanism is established for the formulation of the proposed control methodology. The stability of the control approach is analysed, and the convergence of the tracking errors to achieve the generalised impedance is proven theoretically. Desirable control performances in following the desired motion and force trajectories are demonstrated in the experimental study. An important advantage of this control methodology is that this approach does not require the exact values for the system parameters and the force Conversion Function in the physical realisation. This proposed compliant manipulation control methodology is useful for the implementation of high performance flexure-based micro/nano manipulation applications demanding for both sensing and control of motion and force trajectories.
Hwee Choo Liaw - One of the best experts on this subject based on the ideXlab platform.
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robust adaptive constrained motion tracking control of piezo actuated flexure based mechanisms for micro nano manipulation
IEEE Transactions on Industrial Electronics, 2011Co-Authors: Hwee Choo Liaw, Bijan ShirinzadehAbstract:This paper presents a robust adaptive constrained motion tracking control methodology for piezo-actuated flexure-based micro/nano manipulation mechanisms. This unique control approach is established for the tracking of desired motion trajectories in a constrained environment exhibiting some degree of uncertain stiffness. The control methodology is also formulated to accommodate not only the parametric uncertainties and unknown force Conversion Function, but also nonlinearities including the hysteresis effect and external disturbances in the motion systems. In this paper, the equations for the dynamic modeling of a flexure-hinged four-bar micro/nano manipulation mechanism operating in a constrained environment are established. A lumped parameter dynamic model that combines the piezoelectric actuator and the micro/nano manipulation mechanism is developed for the formulation of the control methodology. Stability analysis of the proposed closed-loop system is conducted and the convergence of the motion tracking errors is proven theoretically. Furthermore, precise motion tracking ability in following a desired motion trajectory is demonstrated in the experimental study. An important advantage of this control approach is that it does not require the exact values for the system parameters and the force Conversion Function in the physical realization. This proposed constrained motion tracking control methodology is very useful for applications demanding high-precision motion tracking with force sensing and feedback.
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robust generalised impedance control of piezo actuated flexure based four bar mechanisms for micro nano manipulation
Sensors and Actuators A-physical, 2008Co-Authors: Hwee Choo Liaw, Bijan ShirinzadehAbstract:This paper presents a novel robust generalised impedance control methodology for piezo-actuated flexure-based four-bar micro/nano manipulation mechanisms. This control approach is proposed for compliant manipulation in which desired motion and force trajectories are controlled to achieve a specified generalised impedance. The control methodology is also formulated to accommodate not only the parametric uncertainties and unknown force Conversion Function, but also non-linearities including the hysteresis effect and external disturbances in the motion systems. In this paper, the equations for dynamic modelling of a flexure-hinged four-bar micro/nano mechanism making contact with its environment are established. A lumped parameter dynamic model that combines the piezoelectric actuator and the micro/nano mechanism is established for the formulation of the proposed control methodology. The stability of the control approach is analysed, and the convergence of the tracking errors to achieve the generalised impedance is proven theoretically. Desirable control performances in following the desired motion and force trajectories are demonstrated in the experimental study. An important advantage of this control methodology is that this approach does not require the exact values for the system parameters and the force Conversion Function in the physical realisation. This proposed compliant manipulation control methodology is useful for the implementation of high performance flexure-based micro/nano manipulation applications demanding for both sensing and control of motion and force trajectories.
Suzannah Rutherford - One of the best experts on this subject based on the ideXlab platform.
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a method and on line tool for maximum likelihood calibration of immunoblots and other measurements that are quantified in batches
PLOS ONE, 2016Co-Authors: Steven S Andrews, Suzannah RutherfordAbstract:Experimental measurements require calibration to transform measured signals into physically meaningful values. The conventional approach has two steps: the experimenter deduces a Conversion Function using measurements on standards and then calibrates (or normalizes) measurements on unknown samples with this Function. The deduction of the Conversion Function from only the standard measurements causes the results to be quite sensitive to experimental noise. It also implies that any data collected without reliable standards must be discarded. Here we show that a “1-step calibration method” reduces these problems for the common situation in which samples are measured in batches, where a batch could be an immunoblot (Western blot), an enzyme-linked immunosorbent assay (ELISA), a sequence of spectra, or a microarray, provided that some sample measurements are replicated across multiple batches. The 1-step method computes all calibration results iteratively from all measurements. It returns the most probable values for the sample compositions under the assumptions of a statistical model, making them the maximum likelihood predictors. It is less sensitive to measurement error on standards and enables use of some batches that do not include standards. In direct comparison of both real and simulated immunoblot data, the 1-step method consistently exhibited smaller errors than the conventional “2-step” method. These results suggest that the 1-step method is likely to be most useful for cases where experimenters want to analyze existing data that are missing some standard measurements and where experimenters want to extract the best results possible from their data. Open source software for both methods is available for download or on-line use.
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a novel method and simple on line tool for maximum likelihood calibration of immunoblots and other measurements that are quantified in batches
bioRxiv, 2015Co-Authors: Steven S Andrews, Suzannah RutherfordAbstract:Experimental measurements require calibration to transform measured signals into physically meaningful values. The conventional approach has two steps: the experimenter deduces a Conversion Function using measurements on standards and then calibrates (or normalizes) measurements on unknown samples with this Function. The deduction of the Conversion Function from only the standard measurements causes the results to be quite sensitive to experimental noise. It also implies that any data collected without reliable standards must be discarded. Here we show that a new "1-step calibration method" reduces these problems for the common situation in which samples are measured in batches, where a batch could be an immunoblot (Western blot), an enzyme-linked immunosorbent assay (ELISA), a sequence of spectra, or a microarray, provided that some sample measurements are replicated across multiple batches. The 1- step method computes all calibration results iteratively from all measurements. It returns the most probable values for the sample compositions under the assumptions of a statistical model, making them the maximum likelihood predictors. It is less sensitive to measurement error on standards and enables use of some batches that do not include standards. In direct comparison of both real and simulated immunoblot data, the 1-step method consistently exhibited smaller errors than the conventional "2-step" method. These results suggest that the 1-step method is likely to be most useful for cases where experimenters want to analyze existing data that are missing some standard measurements and where experimenters want to extract the best results possible from their data. Simple open source software for both methods is available for download or on-line use.
Sandro Morasca - One of the best experts on this subject based on the ideXlab platform.
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convertibility of Function points into cosmic Function points a study using piecewise linear regression
Information & Software Technology, 2011Co-Authors: Luigi Lavazza, Sandro MorascaAbstract:Background: COSMIC Function Points and traditional Function Points (i.e., IFPUG Function Points and more recent variation of Function Points, such as NESMA and FISMA) are probably the best known and most widely used Functional Size Measurement methods. The relationship between the two kinds of Function Points still needs to be investigated. If traditional Function Points could be accurately converted into COSMIC Function Points and vice versa, then, by measuring one kind of Function Points, one would be able to obtain the other kind of Function Points, and one might measure one or the other kind interchangeably. Several studies have been performed to evaluate whether a correlation or a Conversion Function between the two measures exists. Specifically, it has been suggested that the relationship between traditional Function Points and COSMIC Function Points may not be linear, i.e., the value of COSMIC Function Points seems to increase more than proportionally to an increase of traditional Function Points. Objective: This paper aims at verifying this hypothesis using available datasets that collect both FP and CFP size measures. Method: Rigorous statistical analysis techniques are used, specifically Piecewise Linear Regression, whose applicability conditions are systematically checked. The Piecewise Linear Regression curve is a series of interconnected segments. In this paper, we focused on Piecewise Linear Regression curves composed of two segments. We also used Linear and Parabolic Regressions, to check if and to what extent Piecewise Linear Regression may provide an advantage over other regression techniques. We used two categories of regression techniques: Ordinary Least Squares regression is based on the usual minimization of the sum of squares of the residuals, or, equivalently, on the minimization of the average squared residual; Least Median of Squares regression is a robust regression technique that is based on the minimization of the median squared residual. Using a robust regression technique helps filter out the excessive influence of outliers. Results: It appears that the analysis of the relationship between traditional Function Points and COSMIC Function Points based on the aforementioned data analysis techniques yields valid significant models. However, different results for the various available datasets are achieved. In practice, we obtained statistically valid linear, piecewise linear, and non-linear Conversion formulas for several datasets. In general, none of these is better than the others in a statistically significant manner. Conclusions: Practitioners interested in the Conversion of FP measures into CFP (or vice versa) cannot just pick a Conversion model and be sure that it will yield the best results. All the regression models we tested provide good results with some datasets. In practice, all the models described in the paper - in particular, both linear and non-linear ones - should be evaluated in order to identify the ones that are best suited for the specific dataset at hand.
Banjong Boonchom - One of the best experts on this subject based on the ideXlab platform.
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non isothermal kinetics of the thermal decomposition of sodium oxalate na2c2o4
Journal of Thermal Analysis and Calorimetry, 2012Co-Authors: Nopsiri Chaiyo, Banjong Boonchom, Rangson Muanghlua, Surasak Niemcharoen, Panpailin Seeharaj, Naratip VittayakornAbstract:The thermal transformation of Na2C2O4 was studied in N2 atmosphere using thermo gravimetric (TG) analysis and differential thermal analysis (DTA). Na2C2O4 and its decomposed product were characterized using a scanning electron microscope (SEM) and the X-ray diffraction technique (XRD). The non-isothermal kinetic of the decomposition was studied by the mean of Ozawa and Kissinger–Akahira–Sunose (KAS) methods. The activation energies (Eα) of Na2C2O4 decomposition were found to be consistent. Decreasing Eα at increased decomposition temperature indicated the multi-step nature of the process. The possible Conversion Function estimated through the Liqing–Donghua method was ‘cylindrical symmetry (R2 or F1/2)’ of the phase boundary mechanism. Thermodynamic Functions (ΔH*, ΔG* and ΔS*), calculated by the Activated complex theory and kinetic parameters, indicated that the decomposition step is a high energy pathway and revealed a very hard mechanism.
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study of kinetics and thermodynamics of the dehydration reaction of alpo4 h2o
Journal of Thermal Analysis and Calorimetry, 2010Co-Authors: Banjong Boonchom, Samart KongtaweelertAbstract:Abstract The kinetics and thermodynamics of the thermal dehydration of aluminum phosphate monohydrate, AlPO4 · H2O were studied using thermogravimetry (TG-DTG-DTA) at four heating rates in dry air atmosphere. The activation energies of the dehydration step of AlPO4 · H2O were calculated through the methods of Friedman (FR) and Flynn–Wall–Ozawa (FWO) and the possible Conversion Function has been estimated through the Achar and Li–Tang equations. The independent activation energies on extent of Conversions and the better kinetic model of the dehydration reaction for AlPO4 · H2O indicate single kinetic mechanism and the F 2.05 model as a simple n-order reaction of “chemical process or mechanism no-invoking equation”, respectively. The positive values of ΔH# and ΔG# for the dehydration reaction show that it is endothermic and non-spontaneous process and it is connected with the introduction of heat. The kinetic and thermodynamic Functions calculated for the dehydration reaction by different techniques and met...