Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Journal Article (12)
- Conference Paper (8)
- Ac (4)
- Calorimetric (3)
- Htsc (3)
-
- Current (2)
- Different (2)
- High (2)
- Loss (2)
- Losses (2)
- Measurement (2)
- Method (2)
- Methods (2)
- Polypyrrole (2)
- Rate (2)
- Robot (2)
- Robots (2)
- Scara (2)
- Trajectories (2)
- Velocity (2)
- Wires (2)
- 2 (1)
- Accuracy (1)
- Actuators (1)
- Adaptive (1)
- Alternating (1)
- Application (1)
- Applications (1)
- Approach (1)
- Behaviour (1)
Articles 1 - 20 of 20
Full-Text Articles in Engineering
Innovative Calorimetric Ac Loss Measurement Of Htsc For Power Applications, K See, C Cook, S Dou
Innovative Calorimetric Ac Loss Measurement Of Htsc For Power Applications, K See, C Cook, S Dou
Christopher Cook
The applications of high-temperature superconductors (HTS) in electric power components have been widely reported and various studies have been made to define their alternating current (AC) losses-a key design parameter for many practical high power electrical engineering applications. However, very few studies over the range 25 to 45 K have been conducted even though this is one of the favored temperature ranges for cost-effective applications of HTS. Methods and techniques used to characterize and measure these losses have been so far grouped into `electrical' and `calorimetric' approaches with external conditions set to resemble the application conditions. In this paper, we …
Transport Critical Current Of Mgb2 Wires: Pulsed Current Of Varying Rate Compared To Direct Current Method, K See, X Xu, J Horvat, C Cook, S. Dou
Transport Critical Current Of Mgb2 Wires: Pulsed Current Of Varying Rate Compared To Direct Current Method, K See, X Xu, J Horvat, C Cook, S. Dou
Christopher Cook
The measurement of transport critical current (Ic) forMgB2 wires and tapes has been investigated with two different techniques, the conventional four-probe arrangement with direct current (DC) power source, and a tailored triangle pulse at different rates of current change. The DC method has been widely used and practiced by various groups, but suffers from inevitable heating effects when high currents are used at low magnetic fields. The pulsed current method has no heating effects, but the critical current can depend on the rate of the current change (dI/dt) in the pulse. Our pulsed current measurements with varying dI/dt show that …
Drilling Of Carboncomposites Using Aoneshotdrillbit. Part I: Five Stage Representation Of Drilling And Factors Affecting Maximum Force And Torque, Marta Fernandes, C. Cook
Drilling Of Carboncomposites Using Aoneshotdrillbit. Part I: Five Stage Representation Of Drilling And Factors Affecting Maximum Force And Torque, Marta Fernandes, C. Cook
Christopher Cook
The thrust force and torque produced during drilling contain important information related to the quality of the hole and the wear of the drillbit[1]. In this paper, the force and torque produced during drilling of carbon fibre using a ‘oneshot’ drillbit is investigated. The signals in the time domain were divided into stages and common problems and defects associated with each stage discussed. It is also shown how tool wear and thickness of the workpiece affect the thrust force and torque throughout the drilling process. The findings of this paper are used to develop a mathematical model of the maximum …
Measurements Of Ac Losses In Htsc Wires Exposed To An Alternating Field Using Calorimetric Methods, Tri Hardono, Christopher Cook, Jian Xun Jin
Measurements Of Ac Losses In Htsc Wires Exposed To An Alternating Field Using Calorimetric Methods, Tri Hardono, Christopher Cook, Jian Xun Jin
Christopher Cook
Calorimetric methods for AC loss measurement for short superconducting wires have been investigated. The design, operation and results obtained from an experimental calorimeter are described. With these methods the total loss of a short superconducting sample exposed to a 50 Hz alternating field, both perpendicular and axial, have been measured with an accuracy of microwatts per centimeter. The sample is a 6 centimeter long (Bi,Pb)SrCaCuO-2223 silver-sheathed multifilamentary wire prepared by powder-in-tube techniques. The hysteresis part of the loss may be obtained by taking the eddy current component of the silver sheath from the total loss and by neglecting the coupling …
Magnetic Saturable Reactor Type Hts Fault Current Limiter For Electrical Application, Jian Xun Jin, S Dou, Christopher Cook, C Grantham, M Apperley, Timothy Beales
Magnetic Saturable Reactor Type Hts Fault Current Limiter For Electrical Application, Jian Xun Jin, S Dou, Christopher Cook, C Grantham, M Apperley, Timothy Beales
Christopher Cook
An electricalfaultcurrentlimiter (FCL) developed based on the principle of a magneticsaturablereactor requires a high current ampere-turn coil as its dc bias, and this coil is necessary to use a high temperature superconducting (HTS) winding. This HTS FCL has been studied, and identified with several advantages compared to other HTS FCLs, and therefore is further considered for its practical industry application.
Modelling Of Polypyrrole Actuators, Mehrdad Bahrami Samani, Geoffrey Spinks, Philip Whitten, Christopher Cook
Modelling Of Polypyrrole Actuators, Mehrdad Bahrami Samani, Geoffrey Spinks, Philip Whitten, Christopher Cook
Christopher Cook
Conducting polymers (CP) are a promising area in the field of micro actuators, and have potential applications in micro robotics. Their properties are modelled as having an electro-chemical active component and a passive viscoelastic component. Methods exist to model the passive component as a configuration of springs and dashpots and the electro-active effects as a strain generator. Typically, the strain is assumed to be proportional to the charge transferred, and the two components are assumed to be independent. We show that there is a significant interaction between the two components for polypyrrole actuators, by observing the dynamic elastic modulus whilst …
Quartz Crystal Microbalance Study Of Volume Changes And Modulus Shift In Electrochemically Switched Polypyrrole, Mehrdad Bahrami-Samani, Christopher Cook, John Madden, Geoffrey Spinks, Philip Whitten
Quartz Crystal Microbalance Study Of Volume Changes And Modulus Shift In Electrochemically Switched Polypyrrole, Mehrdad Bahrami-Samani, Christopher Cook, John Madden, Geoffrey Spinks, Philip Whitten
Christopher Cook
The performance of conducting polymers as actuators is determined by a complicated series of molecular processes that occur as a result of oxidation and reduction of the polymer. In particular, the amount of actuation strain generated for a given voltage stimulus is determined by the number and type of ions (and solvent) that enter and leave the polymer and changes in the mechanical properties (particularly elastic modulus) of the polymer. In this paper, we present the effects of cyclic voltammetry on the shear modulus and volume of polypyrrole in two different electrolytes: propylene carbonate and an ionic liquid. An electrochemical …
Calorimetric Methods For Measuring Ac Losses In Htsc Tapes Carrying Currents, T Hardono, Christopher Cook, Jian Xun Jin
Calorimetric Methods For Measuring Ac Losses In Htsc Tapes Carrying Currents, T Hardono, Christopher Cook, Jian Xun Jin
Christopher Cook
Power engineering applications of HTSC tapes are often restricted by AC losses. Both direct and indirect methods have been used to measure AC losses in short samples. This paper reports on the development of a direct calorimetric method for AC loss measurement techniques for short tapes based on measurements of slight temperature increases of the sample. This method has the advantage of measuring total losses in the HTSC sample. The test rig discussed here consists of a calorimeter and associated data collection and analysis equipment. The calorimeter uses a sensitive temperature sensor and an ohmic heater, needed for the calibration …
A Monocular Approach To Depth Maps Generation, H Shi, Fazel Naghdy, Christopher Cook
A Monocular Approach To Depth Maps Generation, H Shi, Fazel Naghdy, Christopher Cook
Christopher Cook
In this paper, amonocularapproach for generation of the depthmaps of an object using computer vision is proposed. In this technique the object is immersed in a colour liquid and a single plan view is captured by a CCD camera. Due to the absorption property of the colour liquid, the intensity of the pixels of the captured image is modulated by the depths of the object along the camera axis. The depthmaps are generated from the grey level image by consecutive segmentation of the image into binary images at various thresholds. The depthmaps produced are parallel layers located in planes normal …
Drilling Of Carbon Composites Using A One Shot Drill Bit. Part 2 Empirical Modeling Of Maximum Thrust Force, Marta Fernandes, Christopher Cook
Drilling Of Carbon Composites Using A One Shot Drill Bit. Part 2 Empirical Modeling Of Maximum Thrust Force, Marta Fernandes, Christopher Cook
Christopher Cook
In order to extend tool life and improve quality of hole drilling in carboncomposite materials, a better understanding of ‘oneshot’ hole drilling is required. This paper describes the development of an empirical model of the maximum thrust force and torque produced during drilling of carbon fiber with a ‘oneshot’ drillbit. Shaw's simplified equations are adapted in order to accommodate for tool wear and used to predict maximum thrust force and torque in the drilling of carboncomposite with a ‘oneshot’ drillbit. The mathematical model is dependent on the number of holes drilled previously, the geometry of the drillbit, the feed used …
Robust Adaptive Control For Industrial Robots - A Decentralized System Method, M Liu, Christopher Cook
Robust Adaptive Control For Industrial Robots - A Decentralized System Method, M Liu, Christopher Cook
Christopher Cook
An adaptive control approach is presented for the tracking control of industrial robots. The approach utilizes the fact that a robot model can be described by equations that are linear in the system's unknown parameters. Taking uncertainties into account, the resulting controller has the property of robustness. The proof of stability and analytical results of the boundness of position tracking errors are given. By introducing filter operations in state measurements, the approach avoids the difficulty of measuring the accelerations of the robots' actuators. Simulation results are also presented
Comparison Of Rotary Valve And Blowtank Feed Rate Capacities, David Hastie, Peter Wypych, Ian Frew, Christopher Cook
Comparison Of Rotary Valve And Blowtank Feed Rate Capacities, David Hastie, Peter Wypych, Ian Frew, Christopher Cook
Christopher Cook
Rotary valves and blowtanks are widely used in industry for the pneumatic conveying of products, each having their pros and cons depending on the required application. This paper aims to show the differing results that can be obtained when conveying a product through a common pipeline using either a drop-through rotary valve or a bottom discharge blowtank. The rotary valve system has a number of issues, the main one being air leakage effects, whereas the blowtank system does not as it is an enclosed unit. The results of these experiments showed dramatic differences in product tonnage.
Dynamics Characteristics Of A Scara Robot Subject To Nc2 Velocity Trajectories With Different Payloads, M Ibrahim, Christopher Cook
Dynamics Characteristics Of A Scara Robot Subject To Nc2 Velocity Trajectories With Different Payloads, M Ibrahim, Christopher Cook
Christopher Cook
This paper presents a computer study that was conducted on the dynamics of arobot of aSCARA geometrical configuration. All links of this robot were moving in NC2 (Numerical Control 2) velocitytrajectories. The study was conducted to investigate the effect of payload variation on the gravitational (potential) as well as inertial and centripetal/coriolis (kinetic) forces. The results of these effects are discussed. All the simulation software was written in extended ANSI FORTRAN 77 and run on an HP 9000/550 computer using the UNIX operating system.
Dynamic Behaviour Of A Scara Robot With Links Subjected To Different Velocity Trajectories, Christopher Cook, M Ibrahim, A Tieu
Dynamic Behaviour Of A Scara Robot With Links Subjected To Different Velocity Trajectories, Christopher Cook, M Ibrahim, A Tieu
Christopher Cook
The dynamics of a mechanical manipulator have the inherent characteristics of being highly non-linear and strongly coupled due to the interaction of the inertial, centripetal, coriolis and gravitational forces. These characteristics produce difficulties in predicting the dynamic behaviour of a given manipulator's structure. These interactive forces depend largely on the geometrical configuration and operational conditions of a manipulator. Therefore, it is essential to investigate the dynamics behaviour under different conditions in order to obtain an optimal design. This paper presents a study of the dynamics behaviour of a robot's arm with particular reference to the mechanical manipulator being designed by …
Novel Ac Loss Measurement Of High T C Superconducting Long Wire, Jian Xun Jin, S Dou, T Hardono, Christopher Cook
Novel Ac Loss Measurement Of High T C Superconducting Long Wire, Jian Xun Jin, S Dou, T Hardono, Christopher Cook
Christopher Cook
A novel method for AC loss measurement of a long length high Tc superconducting (HTSC) wire has been investigated. An 8 m long (Bi,Pb)2Sr2Ca2Cu3O10+x Ag clad multifilament wire was selected to prepare a special sample in which the inductive voltage induced by AC transport currents can be cancelled. Consequently the resistive voltage of the HTSC long wire can be measured. The HTSC sample has been tested at 77 K with AC transport currents up to 3Ic and at various frequencies from 10 Hz to 1 kHz. The loss of the (Bi,Pb)2Sr2Ca2Cu3O10+x Ag clad wire related to its zero field AC …
Mechanical Performance Of Ppy Helix Tube Microactuator, Mehrdad Bahrami Samani, Geoffrey Spinks, Christopher Cook
Mechanical Performance Of Ppy Helix Tube Microactuator, Mehrdad Bahrami Samani, Geoffrey Spinks, Christopher Cook
Christopher Cook
Conducting polymer actuators with favourable properties such as linearity, high power density and compliance are of increasing demand in micro applications. These materials generate forces over two times larger than produced by mammalian skeletal muscles. They operate to convert electro chemical energy to mechanical stress and strain. On the other hand, the application of conducting polymers is limited by the lack of a full description of the relation between four essential parameters: stress, strain, voltage and current. In this paper, polypyrrole helix tube micro actuator mechanical characteristics are investigated. The electrolyte is propylene carbonate and the dopant is TBA. PF6. …
Improved Positional Accuracy Of Robots With High Nonlinear Friction Using A Modified Impulse Controller, Stephen Van Duin, Christopher Cook, Zheng Li, Gursel Alici
Improved Positional Accuracy Of Robots With High Nonlinear Friction Using A Modified Impulse Controller, Stephen Van Duin, Christopher Cook, Zheng Li, Gursel Alici
Christopher Cook
This paper presents a modified impulse controller to improve the steady state positioning of a SCARA robot having characteristics of high nonlinear friction. A hybrid control scheme consisting of a conventional PID part and an impulsive part is used as a basis to the modified controller. The impulsive part uses short width torque pulses to provide small impacts of force to overcome static fiction and move a robot manipulator towards its reference position. It has been shown that this controller can greatly improve a robot’s accuracy in position tracking. However, the system in attempting to reach steady state will inevitably …
Postgraduate And Undergraduate Mechatronics' Courses At The University Of Wollongong, C. Cook, Fazel Naghdy, F. De Boer
Postgraduate And Undergraduate Mechatronics' Courses At The University Of Wollongong, C. Cook, Fazel Naghdy, F. De Boer
Christopher Cook
This paper outlines the University's involvement with industry based manufacturing projects, and how this has lead to the recent establishment of postgraduate and undergraduate mechatronics degrees. The nature of the industrial projects is described with examples of specific problems, test equipment and experimental rigs given. This work can be used to explain the reasons for the design of the mechatronics courses at Wollongong. A new teaching methodology particularly suitable for mechatronic's education is also discussed.
Characterisation And Bending Modeling Of Conducting Polymer Actuators For Use In Micro/Nano Manipulation, G. Alici, B. Mui, C. Cook
Characterisation And Bending Modeling Of Conducting Polymer Actuators For Use In Micro/Nano Manipulation, G. Alici, B. Mui, C. Cook
Christopher Cook
As research efforts towards making functional micro/nano robotics system gather more momentum, there is an increasing need for new actuators that can not only be suitable to miniaturization, but also be free from sliding and rolling elements so that they can generate a motion resolution and accuracy in a submicron range. Conducting polymer actuators have many features to satisfy such a strict requirements. Before introducing them to the micro/nano robotics world, it is necessary to investigate into their actuation mechanism and the smallest displacement they can generate. In this paper, we report on the characterization and modelling of a strip-type …
Results Of Ac Loss Tests On Twisted And Untwisted Htsc Tape Exposed To An External Field, T. Hardono, C. Cook, F. Darmann
Results Of Ac Loss Tests On Twisted And Untwisted Htsc Tape Exposed To An External Field, T. Hardono, C. Cook, F. Darmann
Christopher Cook
This paper presents the results of magnetic losstests on twisted and untwisted 37 multifilaments tapes exposed to an alternating field at power frequencies. The losses are measured using calorimetric methods, which are capable of measuring losses in short tapes with the accuracy of several microwatts per centimeter of tape. The losses of the tape due to the longitudinal field of the untwisted tape agree well with theoretical calculations. The measurement results on the twisted filament tape, with 50-mm twist pitch, show that the losses are slightly lower than that in the untwisted tape. This is due to the reduction of …