http://www.mecheng.adelaide.edu.au/anvc/ List of the last 10 recently entered Projects for the ANVC group. &lt;br&gt;&lt;font size=1&gt;&lt;b&gt;Hint:&lt;/b&gt; You can pass the options through the URL by modifying the URL such that &quot;.php&quot; is replaced with &quot;.php?itcount=20&amp;shorttitle=1&amp;dateprefix=0&quot; &lt;/font&gt; en-us Automated (mailto:) Pierre Dumuid (mailto:pierre.dumuid@adelaide_xx_edu_xx_au) Copyright 2008, Adelaide University Thu Aug 21 8:41:21 EIT 2008 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=61 <p></p> 2008--0-1-T14: 1:3:+00:00 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=62 <p>During the lift-off of a launch vehicle, the acoustic pressure fluctuations caused by the engine exhaust gases produce high noise levels inside the cavity of the fairing and can damage the payload inside the fairing. Hence reducing the noise transmitted into the payload bay is an important area of research. This study investigates the external acoustic pressure excitations on the fairing of a launch vehicle during the lift-off acoustic environment. In particular, it investigates the external sound pressure levels in the low frequency range from 50Hz to 400Hz, on the fairing during the lift-off of a launch vehicle. </p> Mir Md Maruf Morshed, Colin Hansen, Anthony Zander 2008--0-1-T14: 1:3:+00:00 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=1 <p>Active noise control systems aim to reduce noise by creating anti-noise using controller driven loudspeakers. Early work in the field of active noise control focussed on achieving global control where the objective was to reduce the noise throughout the entire acoustic domain of interest, for instance a car interior. Global control does not always attenuate the noise to an acceptable level in practical problems, especially in modally dense enclosures and in sound fields which have a large spatial variance. In this case, local control might be the only feasible solution. Unfortunately, local control generally achieves the greatest noise reductions at the error sensor locations, which might not always be the location where the maximum attenuation is required. Furthermore, the zone of quiet around the error sensors tends to be very small. Two methods to overcome the problems encountered in local active noise control systems are currently under investigation. The first method aims to extend the zone of quiet by using either an energy density control strategy or a spatial control strategy. The second method, called virtual sensing, aims to move the zone of quiet away from the physical microphones to the desired location of maximum attenuation. Both methods have the potential to improve the performance of a local active noise control system. This project is focussed on developing new and improved sensing and control methodologies for local active noise control systems by combining both methods.</p> Ben Cazzolato and Dick Petersen 2008--0-1-T11: 0:8:+00:00 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=54 <p>There are applications where it would be beneficial to use structural transducers for acoustic/noise sensing. Such systems may include systems where the sound source is a radiating structure, such as in vehicle cabins. For instance, structural transducers can be attached to the structure inside a vehicle cabin and a virtual sensing strategy can be used to predict the acoustic properties within the cabin. This virtual sensing strategy can then be combined with an active vibration/noise control method for reducing the noise level inside the cabin. A virtual sensing and control method will be developed for the purpose of creating multiple zones of quiet for systems where the noise is radiated from a complex radiating structure, allowing the method to be used for practical applications.</p> Dunant Halim and Ben Cazzolato 2008--0-1-T11: 0:8:+00:00 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=59 <p>An Australian Acoustical Society educational grant has sponsored the development of an interface between the Boundary Element code <A HREF="http://www.mecheng.adelaide.edu.au/anvc/helm3d/">Helm3D</A> and the numerical simulation pre/post processor GiD. Helm3D is a text driven three-dimensional BEM code written in Fortran, available with purchase of a relatively inexpensive book, and GiD, although a commercial product, has a limited node demo version freely available. A tutorial has been written that demonstrates the capability of BEM as well as teaches the fundamentals of acoustics in two application areas: interior acoustics and external acoustic radiation. It is envisaged that the availability of the interface and tutorial will accelerate the uptake of BEM by the wider acoustics community.</p> Rick Morgans, Laura Brooks 2008--0-1-T11: 0:8:+00:00 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=53 <p>The applicability of Active Noise Control (ANC) systems to minimise low frequency noise in enclosures has been a key area of interest in recent years and is now reasonably well understood. Local control at one or more points within an enclosure, such as a mining vehicle cabin, has successfully been achieved through the use of loudspeakers as control sources. However, typical ANC systems struggle to adapt quickly and smoothly as the required location of control is moved. Additionally, the control sources tend to be omnidirectional, resulting in locations away from the zone of interest being adversely affected by the presence of the control source. Therefore, any additional people in the enclosure, but not within the zone of control, may actually experience even higher levels of discomfort than they would without a control system in place. This project intends to ameliorate these problems through beam-forming using an array of conventional loudspeakers.</p> Laura Brooks 2008--0-1-T11: 0:8:+00:00 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=13 <p>Electric motors account for 95% of all prime movers in industrialised nations, and among these, three-phase induction motors consume typically 40 to 50% of all the generated electric energy. Induction motors are inherently reliable and require minimum maintenance. However like other motors, they eventually deteriorate and fail. This is mainly due to a combination of environmental, duty and installation related factors. The principal aim of this project, which is funded by The Australian Research Council and National Instruments is to use hardware and custom-built signal processing and classification software tools to provide the necessary technology for the effective diagnosis and prediction of incipient failures in induction motors. This is being achieved by Developing a comprehensive database of non-invasive sensor measurements of motors with known faults. Analysing this database to obtain a detailed understanding of the effect of the faults on each sensor output. Developing fault detection techniques to distinguish faults under practical operating conditions of motors, including light load. Implementation of a continuous monitoring system with remote access capability.</p> Colin Hansen 2008--0-1-T11: 0:8:+00:00 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=14 <p>Magnetic bearings are very attractive in industrial environments because they are practically frictionless and have very low energy losses. However, they have a tendency to become unstable and require a very sophisticated control system to keep them operational. To be able to avoid catastrophic failures with a high degree of certainty, it is necessary to develop a better understanding of the non-linear phenomena that characterise the behaviour of this class of bearing. The aim of this project, funded by the Australian Research Council is to gain insight into the effects of non-linearities on the dynamic behaviour of active magnetic bearings(AMBs), and the influence of non-linearities on their performance. Attention is being focussed on stability analysis, bifurcation control, malfunction diagnosis, determination of stable operating conditions, prediction of AMB performance, and on aspects of non-linear dynamic behaviour including bifurcations, coexistence of multiple solutions and amplitude-modulated motions. Specific aims of the project are to: 1) investigate the effects of geometric coupling and non-linear force relationships on the dynamic behaviour of the AMBs; 2) investigate the effects of the non-linear force relationship incorporating time delays, saturation of magnetic material, saturation of power amplifier, limitation of the control current, and eddy current effect, respectively, on the dynamic behaviour and the performance of the AMBs; 3) investigate the effects of the combination of three or more components of non-linearity on the dynamic behaviour and performance of the AMBs; 4) determine the stability region of the AMBs, the critical values of time delays, and the parameter regimes for normal operation of the AMBs; 5) analyze the non-linear response of rotor-AMB systems under primary, sub-harmonic, and super-harmonic resonance conditions; 6) explore the parameter regions for existence of multiple solutions, investigate local and global bifurcations, and periodically- and chaotically-amplitude modulated responses; 7) develop a non-linear control approach from the viewpoint of bifurcation control to control saddle-node and Hopf bifurcations, thereby eliminating the occurrence of jump phenomena and amplitude modulated responses; 8) investigate the effect of the non-linearities on the dynamic behaviour of self-sensing magnetic bearings, and develop an appropriate model for the precise estimation of the rotor position; 9) investigate the transient and steady state dynamic behaviour of the AMBs during pole failures; 10) investigate the influence of the non-linearities on the controller design; 11) provide a precise model for the design of control system; and 12) provide guidelines for the design of control system after developing a thorough understanding of the non-linear dynamics of the AMBs.</p> Colin Hansen 2008--0-1-T11: 0:8:+00:00 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=57 <p>The aim of this study is to design an Adaptive Helmholtz Resonator (AHR), which when fixed on the exhaust duct attenuates the fan and blower noise within the frequency range of 180 Hz to 350 Hz. An AHR has a variable resonance frequency that is achieved by altering its physical dimensions such as the cavity volume or neck length or neck cross- sectional area by the help of a control system, in order to track the changing frequencies of the noise.</p> Sarabjeet Singh, Carl Howard 2008--0-1-T11: 0:8:+00:00 http://www.mecheng.adelaide.edu.au/anvc/projectabstract.php?UID=56 <p>Many techniques for controlling the noise radiated by large structures require a large number of inputs to the controller to produce global attenuation. Unfortunately, processing the large number of inputs required is often beyond the capabilities of current controllers. In attempting to overcome this problem, many researchers have adopted various modal-filtering-type techniques. Such techniques involve resolving a small number of important global quantities (traditionally structural modes) from a large number of sensor measurements. However, current approaches require detailed structural information at the design stage. Determining this for complex, real-world structures may be very difficult, preventing many techniques from going beyond the laboratory. This project involves developing a new sensing system strategy, where a radiated sound field is decomposed using multipole radiation patterns, thereby alleviating the need for detailed structural information. This project involves using structural based measurements allowing for sensors and actuators to be built into the structure to produce a so called smart structure.</p> Nick Burgan 2008--0-1-T11: 0:8:+00:00