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Full-Text Articles in Engineering
Experimental Evaluation Of Adaptive And Variable Structure Control Of Piezoelectric Actuation Systems For Micro/Nano Manipulation, Hwee Choo Liaw, Bijan Shirinzadeh, Denny Oetomo, Gursel Alici
Experimental Evaluation Of Adaptive And Variable Structure Control Of Piezoelectric Actuation Systems For Micro/Nano Manipulation, Hwee Choo Liaw, Bijan Shirinzadeh, Denny Oetomo, Gursel Alici
Gursel Alici
This paper proposes and evaluates an adaptive technique and a variable structure control approach for piezoelectric actuation systems to track specified motion trajectories. The proposed control methodologies are formulated to accommodate unknown or uncertain system parameters, nonlinearities including the hysteresis effect, and external disturbances in the piezoelectric actuation systems without any form of feed-forward compensation. In this study, both control methodologies are demonstrated to possess a promising motion tracking ability experimentally. In comparison, the variable structure control approach is evaluated to be superior to the adaptive technique in the motion tracking control. With the ability to track motion trajectories under …
Special Class Of Positive Definite Functions For Formulating Adaptive Micro/Nano Manipulator Control, Hwee Choo Liaw, Denny Oetomo, Gursel Alici, Bijan Shirinzadeh
Special Class Of Positive Definite Functions For Formulating Adaptive Micro/Nano Manipulator Control, Hwee Choo Liaw, Denny Oetomo, Gursel Alici, Bijan Shirinzadeh
Gursel Alici
This paper presents a special class of positive definite functions for the formulation of adaptive control strategies, specifically in the research of an effective control algorithm for piezoelectric actuation systems in micro/nano manipulation. To deal with the control problems of unknown system parameters, nonlinear hysteresis effects, and disturbances in the piezoelectric actuation systems, an adaptive control methodology is proposed. Using the saturation function derived from a positive definite function to formulate the control methodology, the closed-loop system stability can be guaranteed. Furthermore, the control methodology is proposed to track a desired motion trajectory in position, velocity, and acceleration. In this …
Contact State Determination For Robotic-Based Cylindrical Pair Height Adjustment Under Dynamic Conditions, Prasan I. De Waas Tilakaratna, Bijan Shirinzadeh, Gursel Alici
Contact State Determination For Robotic-Based Cylindrical Pair Height Adjustment Under Dynamic Conditions, Prasan I. De Waas Tilakaratna, Bijan Shirinzadeh, Gursel Alici
Gursel Alici
This paper investigates fine motion strategies associated with the height adjustment manipulations of a cylindrical pair which can be utilised in dynamic assembly and reconfigurable workholding systems. The outer link of the cylindrical pair is held by the end-effector of a 6DOF serial articulated robot. The environment which holds the inner link can be dynamic. Formulations capable of identifying the type of contact between the links and parameters vital for control purposes based on the force and torque data provided by a wrist mounted F/T sensor are established for a generic spatial case. Experimental results indicate that the established methodology …
Robust Control Framework For Piezoelectric Actuation Systems In Micro/Nano Manipulation, Hwee Choo Liaw, Denny Oetomo, Bijan Shirinzadeh, Gursel Alici
Robust Control Framework For Piezoelectric Actuation Systems In Micro/Nano Manipulation, Hwee Choo Liaw, Denny Oetomo, Bijan Shirinzadeh, Gursel Alici
Gursel Alici
Micro/nano manipulation has been identified as one of the key enabling technologies for many emerging challenges. Within this scope, piezoelectric actuators have played major roles in achieving the required nano-resolution motion. This paper proposes a robust control framework for piezoelectric actuation systems to follow specified motion trajectories. The basic concept associated with this methodology lies in the specification of a target performance and the robust control scheme formulation for piezoelectric actuation systems to ensure the convergence of the position tracking error to zero. This control methodology is attractive as its implementation requires only the knowledge of the estimated system parameters …
Evaluation Of Control Techniques For Dip Transfer Gas Metal Arc Welding, Gary Dean, John Norrish, Christopher D. Cook
Evaluation Of Control Techniques For Dip Transfer Gas Metal Arc Welding, Gary Dean, John Norrish, Christopher D. Cook
Christopher Cook
Dip transfer gas metal arc welding (GMAW) is used extensively for high productivity welding of thin sheet steel, and is also useful for positional welding of thicker section steels. Unfortunately in the past, the process has gained a reputation for fusion defects, which becomes more apparent when welding traditionally difficult materials such as coated steels. This reputation can be attributed in some instances to the method of control used and the changeable nature of variables crucial to controlling heat transfer during the welding process. The paper examines the relationship between weld fusion, heat input and current for coated steel welding …
Potential High Resolution Dosimeters For Mrt, E. Brauer-Krisch, Anatoly B. Rosenfeld, Michael L. Lerch, Marco Petasecca, M. Akselrod, J. Sykora, J. Bartz, M. Ptaszkiewicz, P. Olko, A. Berg, M. Wieland, S. Doran, T. Brochard, A. Kamlowski, G. Cellere, A. Paccagnella, Erik A. Siegbahn, Y. Prezado, I. Martinez-Rovira, A. Bravin, Laurent Dusseau, P. Berkvens
Potential High Resolution Dosimeters For Mrt, E. Brauer-Krisch, Anatoly B. Rosenfeld, Michael L. Lerch, Marco Petasecca, M. Akselrod, J. Sykora, J. Bartz, M. Ptaszkiewicz, P. Olko, A. Berg, M. Wieland, S. Doran, T. Brochard, A. Kamlowski, G. Cellere, A. Paccagnella, Erik A. Siegbahn, Y. Prezado, I. Martinez-Rovira, A. Bravin, Laurent Dusseau, P. Berkvens
Anatoly Rozenfeld
Microbeam Radiation Therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600 keV, produced by 2nd and 3rd generation synchrotron sources, such as the National Synchrotron Light Source (NSLS) in the U.S., and the European Synchrotron Radiation Facility (ESRF) in France, respectively. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. A small beam divergence and a filtered white beam spectrum in the energy range between 30 and 250 keV results in the advantage of steep dose gradients with a sharper penumbra than …
Simulation Of Low Dose Positron Emission Mammography Scanner For Global Breast Health Applications, W. J Ryder, I. N Wienberg, P. S Stepanov, A Reznik, M Urdaneta, E Anashkin, M. A Masoomi, Anatoly B. Rosenfeld
Simulation Of Low Dose Positron Emission Mammography Scanner For Global Breast Health Applications, W. J Ryder, I. N Wienberg, P. S Stepanov, A Reznik, M Urdaneta, E Anashkin, M. A Masoomi, Anatoly B. Rosenfeld
Anatoly Rozenfeld
Positron emission mammography ("PEM") is a breast imaging modality that typically involves the administration of relatively high doses of radiotracer. In order to reduce tracer costs and consider PEM for global screening applications, it would be helpful to reduce the required amount of administered radiotracer so that patient dose would be comparable to conventional x-ray mammograms. We performed GATE Monte Carlo investigations of several possible camera configurations. Increasing the detector thickness from 10 to 30 mm, increasing the camera surface area from 5 x 20cm2 to 20 x 20cm2, and applying depth-ofinteraction information to increase the acceptance angle, increased the …
A 3-D Microelectrode System For Dielectrophoretic Manipulation Of Microparticles, Dafeng Chen, Hejun Du, Haiqing Gong, Weihua Li
A 3-D Microelectrode System For Dielectrophoretic Manipulation Of Microparticles, Dafeng Chen, Hejun Du, Haiqing Gong, Weihua Li
Professor Weihua Li
This paper presents a microfluidic system for manipulation and separation of micron-sized particles based on the combined use of negative dielectrophoresis (DEP) and hydrodynamic forces. A 3-D microelectrode structure (so called paired electrode array) are constructed face to face on the top and bottom sides of the microchannel and driven with highfrequency AC voltage to generate dielectrophoretic gates. Depending on the relative strengths of the two forces, particles such as polystyrene beads or cells carrying by a laminar flow can either penetrate the gate or settle there. This gives rise to certain applications including selectively concentrating particles from the flow, …
A Variable Stiffness Mr Damper For Vibration Suppression, Xianzhou Zhang, Weihua Li, Yang Zhou
A Variable Stiffness Mr Damper For Vibration Suppression, Xianzhou Zhang, Weihua Li, Yang Zhou
Professor Weihua Li
This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness damper and analysis its applications in vibration suppression. The MR fluid isolator used a MR valve control unit and bladders to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The effective stiffness and damping coefficients of the isolator under various magnetic fields were identified and the dynamic performances of isolator were evaluated with simulation. …
A 3-D Microelectrode System For Dielectrophoretic Manipulation Of Microparticles, Dafeng Chen, Hejun Du, Haiqing Gong, Weihua Li
A 3-D Microelectrode System For Dielectrophoretic Manipulation Of Microparticles, Dafeng Chen, Hejun Du, Haiqing Gong, Weihua Li
Professor Weihua Li
This paper presents a microfluidic system for manipulation and separation of micron-sized particles based on the combined use of negative dielectrophoresis (DEP) and hydrodynamic forces. A 3-D microelectrode structure (so called paired electrode array) are constructed face to face on the top and bottom sides of the microchannel and driven with highfrequency AC voltage to generate dielectrophoretic gates. Depending on the relative strengths of the two forces, particles such as polystyrene beads or cells carrying by a laminar flow can either penetrate the gate or settle there. This gives rise to certain applications including selectively concentrating particles from the flow, …
Bending Modeling And Its Experimental Verification For Conducting Polymer Actuators Dedicated To Manipulation Applications, Christopher Cook, Gursel Alici, Brian Mui
Bending Modeling And Its Experimental Verification For Conducting Polymer Actuators Dedicated To Manipulation Applications, Christopher Cook, Gursel Alici, Brian Mui
Christopher Cook
No abstract provided.
Novel Tooth Design For A Tubular Linear Motor For Machine Tool Axis, Philip Commins, Jeffrey Moscrop, Christopher Cook
Novel Tooth Design For A Tubular Linear Motor For Machine Tool Axis, Philip Commins, Jeffrey Moscrop, Christopher Cook
Christopher Cook
Permanent magnet tubular linear motors have shown potential for use as direct drives in high precision machine tools. These devices are capable of replacing the traditional ball screw, given their ability to overcome or reduce many of the fundamental mechanical properties that limit the precision performance of the ball screw. However, given the desire from industry to increase speed and acceleration, the physical size of the motor must be minimised while maintaining high force output to increase bandwidth in high precision applications. This paper presents a new optimal tooth design to reduce the frame size of a slotted tubular linear …
Graphene V2o5 Nh2o Xerogel Composite Cathodes For Lithium Ion Batteries, Guodong Du, Kuok Hau Seng, Zaiping Guo, Jun Liu, Wenxian Li, D Z. Jia, Christopher D. Cook, Z Liu, Hua-Kun Liu
Graphene V2o5 Nh2o Xerogel Composite Cathodes For Lithium Ion Batteries, Guodong Du, Kuok Hau Seng, Zaiping Guo, Jun Liu, Wenxian Li, D Z. Jia, Christopher D. Cook, Z Liu, Hua-Kun Liu
Christopher Cook
A layer structured V2O5·nH2O xerogel was synthesized via a simple green hydrothermal technique by dissolving commercial V2O5 powder in de-ionized water and hydrogen peroxide. Graphene–V2O5·nH2O xerogel composites were then prepared by mixing and filtration of as-prepared V2O5·nH2O xerogel and graphene in the desired ratio. The method is a cost effective and energy saving way to prepare nanostructured composites. Structure and morphology were investigated by X-ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, and transmission electron microscopy. Heat treatment at different temperatures could yield V2O5·nH2O xerogels with different amounts of crystal water, and the presence of graphene in the composites …
Simultaneous Activated Carbon Adsorption Within A Membrane Bioreactor For An Enhanced Micropollutant Removal, Xueqing Li, Faisal I. Hai, Long Nghiem
Simultaneous Activated Carbon Adsorption Within A Membrane Bioreactor For An Enhanced Micropollutant Removal, Xueqing Li, Faisal I. Hai, Long Nghiem
Faisal I Hai
Significant adsorption of sulfamethoxazole and carbamazepine to powdered activated carbon (PAC) was confirmed by a series of adsorption tests. In contrast, adsorption of these micropollutants to the sludge was negligible. The removal of these compounds in membrane bioreactor (MBR) was dependent on their hydrophobicity and loading as well as the PAC dosage. Sulfamethoxazole exhibited better removal rate during operation under no or low (0.1 g/L) PAC dosage. When the PAC concentration in MBR was raised to 1.0 g/L, a sustainable and significantly improved performance in the removal of both compounds was observed – the removal efficiencies of sulfamethoxazole and carbamazepine …