School of Mechanical & Mining Engineering Publications  UQ eSpace
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A partial velocity approach to subcycling structural dynamics
http://espace.library.uq.edu.au/view/UQ:64888
Subcycling, or the use of different timesteps at different nodes, can be an effective way of improving the computational efficiency of explicit transient dynamic structural solutions. The method that has been most widely adopted uses a nodal partition. extending the central difference method, in which small timestep updates are performed interpolating on the displacement at neighbouring large timestep nodes. This approach leads to narrow bands of unstable timesteps or statistical stability. It also can be in error due to lack of momentum conservation on the timestep interface. The author has previously proposed energy conserving algorithms that avoid the first problem of statistical stability. However, these sacrifice accuracy to achieve stability. An approach to conserve momentum on an element interface by adding partial velocities is considered here. Applied to extend the central difference method. this approach is simple. and has accuracy advantages. The method can be programmed by summing impulses of internal forces, evaluated using local element timesteps, in order to predict a velocity change at a node. However, it is still only statistically stable, so an adaptive timestep size is needed to monitor accuracy and to be adjusted if necessary. By replacing the central difference method with the explicit generalized alpha method. it is possible to gain stability by dissipating the high frequency response that leads to stability problems. However. coding the algorithm is less elegant, as the response depends on previous partial accelerations. Extension to implicit integration, is shown to be impractical due to the neglect of remote effects of internal forces acting across a timestep interface. (C) 2002 Elsevier Science B.V. All rights reserved.
20070814T19:28:08Z
Daniel, W. J. T.

A ParticleOnly Hybrid Method for NearContinuum Flows
http://espace.library.uq.edu.au/view/UQ:9908
EPSM is a particle simulation method for the simulation of the Euler equations. EPSM is used here as part of a hybrid EPSM/DSMC method for the simulation of near continuum flows. It is used where the flow gradients are not large and the flow is expected to be in an equilibrium state. The gradient of local mean free path has been used to detect those regions where EPSM can be invoked. Results are presented for the unsteady flow of a gas in a shock tube with Knudsen numbers in the initial state of 0.01 and 0.002 either side of the diaphragm (based on the length of the initial lowpressure region). The results for the hybrid method are very close to those for pure DSMC. The execution speed of the hybrid code is 1.75 times that of standard DSMC.
20050215T00:00:00Z
Macrossan, Michael N.

A particle simulation method for the BGK equation
http://espace.library.uq.edu.au/view/UQ:95336
20070823T23:36:10Z
Macrossan, M. N.

A performance evaluation of the CRCMining/P&H electric mining shovel monitor
http://espace.library.uq.edu.au/view/UQ:101869
20070823T20:29:18Z
Reid, A. W.; Chiodi, V.; Hall, A. S.; McAree, P. R.

A Personal Journey towards Interdisciplinary Engineering Education Research: Lessons learned for undergraduate education
http://espace.library.uq.edu.au/view/UQ:204004
20100422T12:07:50Z
Nicola Sochacka; Walter, J.

A perturbation solution for forced convection in a porous saturated duct
http://espace.library.uq.edu.au/view/UQ:119821
Fully developed forced convection through a porous medium bounded by two isoflux parallel plates is investigated analytically on the basis of a BrinkmanForchheimer model. The matched asymptotic expansion method is applied for small values of the Darcy number. For the case of large Darcy number the solution for the BrinkmanForchheimer momentum equation is found in terms of an asymptotic expansion. With the velocity distribution determined, the energy equation is solved using the same asymptotic technique. The results for limiting cases are found to be in good agreement with those available in the literature and the numerical results obtained here.
20071023T18:20:18Z
Hooman, Kamel

A phenomenological approach to the quality index of AlSiMg casting alloys
http://espace.library.uq.edu.au/view/UQ:141345
A simple continuum mechanics model relating the quality index,* Q, to parameters of the deformation curve of alloys A356/357 is presented. The model incorporates the limiting effect of particle cracking on the ductility on a phenomenological base and it is used to predict the behaviour of the quality index as the material is strengthened by either ageing or increased content of Mg. The analysis shows that for every temper there is a matrix strength that maximises the Qvalue. For strong alloys the model suggests that peak ageing can reduce Q. This effect is stronger when the ductility of the material is low. The possibility of using the quality index to optimise the combination of the alloy chemical composition and temper is discussed.
20080610T12:20:00Z
Caceres, C. H.

A porosimetric study of subsurface carboxy oxidation in anodes
http://espace.library.uq.edu.au/view/UQ:318239
Carbon dioxide generated at the electrolytic face of operating anodes permeates the anode structure and reacts to form carbon monoxide. This gasification increases anode porosity and generates a reaction porosity profile, with internal attack decreasing to the limit of C02 permeation into the anode. Mercury porosimetry has been used to establish the mechanism of reaction porosity generation and to define an active pore size range within the anode structure. In all anodes studied, porosity generated by subsurface oxidation was largely in the submicrometre region of the anode pore volume distribution. A model of the anode structure is proposed to account for reaction in these fine pores.
20131128T21:20:15Z
Sadler, B. A; Algie, S. H.

A possible biodegradable magnesium implant material
http://espace.library.uq.edu.au/view/UQ:128772
The different hydrogen evolution rates for Mg immersed in simulated body fluid solutions with and without phosphates signify that the constituents of the body fluid could play different roles in the biodegradation of a magnesium implant. Currebtly, there is still a lack of fundamental understanding of the corrosion behavior of magnesium in the body fluid.
20080218T17:10:48Z
Song, G. L.; Song, S. Z.

Apparatus to Determine Static and Dynamic Elastic Moduli
http://espace.library.uq.edu.au/view/UQ:8832
Conclusions 1. The apparatus makes it possible to concurrently measure ES and ED of cylindrical rock specimens under triaxial conditions in the NX Hoek cell. 2. Accuracy of the apparatus is comparable to usual dynamic modulus testing. 3. Preliminary test results for one particular rock type, show that under triaxial conditions the differences between E D and E S are smaller at high confining pressures than at low confining pressures. Circumstantial evidence suggests that microcracks and microfissures are responsible for this phenomenon. Further work needs to be undertaken in other rock types to substantiate these preliminary findings.
20051220T00:00:00Z
Howarth, D. F.

Applicability of equal channel angular pressing (ECAP) processing to light metals
http://espace.library.uq.edu.au/view/UQ:196304
Equal channel angular pressing (ECAP) is the most promising severe plastic deformation (SPD) technique for fabrication of bulk ultrafine grain materials, compaction of powders nearer to theoretical density, and property enhancement of tubular materials.
20100223T10:00:40Z
Anumalasetty, Venkata Nagasekhar

Applicability of new calcium based material for thermal energy storage
http://espace.library.uq.edu.au/view/UQ:313653
20131108T15:19:15Z
Liu, Wenqiang; Feng, Bo; Wang, Geoff X.

Applicability of viscous and inviscid flow solvers to the hypersonic REST inlet
http://espace.library.uq.edu.au/view/UQ:293426
This paper investigates the applicability of the quicklook inviscid CFD solver Cart3D when analysing a hypersonic REST inlet. The applicability is determined by comparing the inviscid Cart3D solution to that calculated using the full viscous solution methods in the CFD++ software package. Cart3D utilises mesh adaptation, taking the human out of the loop during the meshing process, while the CFD++ domain is manually meshed using MIME grid generator. In CFD++ the viscous effects are captured using a RANS realizable k turbulence model chosen through validation studies and literature review. The captured viscous effects, such as shock boundary layer interactions, are shown to significantly affect the internal inlet flow field. This highlights that the applicability of the inviscid code is limited to the external region about the compression wedge up to the crotch. The trends in mass capture sensitivity to angle of attack and sideslip angle are consistent for both codes. A byproduct of this study is the understanding of appropriate analysis methodologies that may be applied to efficiently investigate future REST inlet design iterations.
20130311T16:18:20Z
Aagon, A.; Abeynayake, D.; Smart, M.

Application and comparison of metaheuristic techniques to reactive power planning problem
http://espace.library.uq.edu.au/view/UQ:224808
This paper presents the application and comparison of metaheuristic techniques to reactive power planning (RPP) problem which involves optimal allocation and combination of tobeinstalled VAr sources to satisfy voltage constraints during normal and contingency states for multiple load levels. The main objective of the proposed RPP problem is to minimize the investment cost through balanced installation of SCs and SVCs while keeping a specified security level and minimizing the amount of load shedding. The problem is formulated as a large scale mixed integer nonlinear programming problem, which is a nonsmooth and nondifferentiable optimization problem using conventional optimization techniques and induces lots of local minima. Among the metaheuristic techniques, genetic algorithm (GA), particle swarm optimization (PSO) and evolutionary particle swarm optimization (EPSO) are applied to solve the RPP problem. To investigate the effectiveness of the metaheuristic techniques, the proposed approaches have been successfully tested on IEEE14 buses, as well as IEEE57 buses test system. The results obtained are compared and the effectiveness of each technique has been illustrated.
20101216T09:00:33Z
Eghbal, Mehdi; Yorino, Naoto; Zoka, Yoshifumi; ElAraby, E. E.

Application of a knowledge and geographical information based system to the environmental impact assessment of an opencast coal mining project
http://espace.library.uq.edu.au/view/UQ:140379
20080610T11:27:05Z
Li, S.; Dowd, P.; Birth, W. J.

Application of a new hot tearing analysis to horizontal direct chill cast magnesium alloy AZ91
http://espace.library.uq.edu.au/view/UQ:148588
20080606T14:40:24Z
Grandfield, J.; Davidson, C. J.; Taylor, J. A.

Application of a new hot tearing analysis to horizontal direct chill cast magnesium alloy AZ91
http://espace.library.uq.edu.au/view/UQ:96647
20070824T00:42:10Z
Grandfield, J. F.; Davidson, C. J.; Taylor, J. A.

Application of artificial neural networks in foundry industry
http://espace.library.uq.edu.au/view/UQ:186772
20091117T14:02:18Z
Wang, Gui; Huang, Tianyou; et al.

Application of baby deck initiation to reduce coal damage during cast blasting
http://espace.library.uq.edu.au/view/UQ:140406
20080610T11:28:31Z
Kanchibotla, S. S.; Scott, A.

Application of Bayesian approach for damage characterization in beams utilizing guided waves
http://espace.library.uq.edu.au/view/UQ:316869
A Bayesian approach for characterizing the damage in beams utilizing guided waves is presented. The proposed methodology treats the damage location, length, depth and the Young's modulus of the material as unknown model parameters. A twostage optimization approach is applied for damage characterization using simulated annealing algorithm to first guarantee that the solution is close to the global optimum, followed by a standard simplex search method that maximizes the probability density function of a damage scenario conditional on the measurement data. One advantage of the proposed method is that instead of only pinpointing the damage location and extent, the uncertainty associated with the damage characterization results is also quantified. A series of comprehensive numerical case studies utilizing the spectral finite element method to model the wave propagation and scattering at the step damage are used to examine the accuracy and robustness of the proposed methodology. The studies include investigations of the influence of practical situations such as the effects of measurement noise, uncertainty of Young's modulus due to the temperature change, and interference of boundary reflections and scattered waves on the damage characterization results.
20131128T00:01:38Z
Ng, C.T.; Veidt, M.; Lam, H. F.

Application of bulk coal selfheating tests to longwall operations
http://espace.library.uq.edu.au/view/UQ:99865
20070824T13:00:03Z
Beamish, B. B.; Phillips, J. D. A.; Brown, M.; Millers, D.

Application of coupled vibration on detection of fatigue cracks in welded structures
http://espace.library.uq.edu.au/view/UQ:102235
20070823T20:47:36Z
Liu, D.; Gurgenci, H.; Veidt, M.

Application of EBSD and TEM to determine eutectic solidification mechanisms
http://espace.library.uq.edu.au/view/UQ:96476
20070824T00:35:13Z
Nogita, K.; Dahle, A. K.; Drennan, J.

Application of edgetoedge matching model to grain refinement in MgAl based alloys
http://espace.library.uq.edu.au/view/UQ:75648
20070815T05:58:48Z
Zhang, M. X.; Kelly, P. M.; Qian, Ma; Taylor, J. A.

Application of edgetoedge matching model to understand the inplane texture of TiSi2 (C49) thin films on (001)(Si) surface
http://espace.library.uq.edu.au/view/UQ:79571
The edgetoedge matching model, which was originally developed for predicting crystallographic features in diffusional phase transformations in solids, has been used to understand the formation of inplane textures in TiSi2 (C49) thin films on Si single crystal (001)si surface. The model predicts all the four previously reported orientation relationships between C49 and Si substrate based on the actual atom matching across the interface and the basic crystallographic data only. The model has strong potential to be used to develop new thin film materials. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
20070815T08:26:13Z
Zhang, M.; Kelly, P. M.

Application of fault tree analysis to coal spontaneous combustion
http://espace.library.uq.edu.au/view/UQ:237248
Fault tree analysis is a powerful risk assessment tool for identifying root causes of an unwanted event that can then be managed with appropriate control measures. This method has been applied to the analysis of a spontaneous combustion event for the five year mine plan of the new Abel Mine, Newcastle, Australia. A team of people with diverse backgrounds provided input to the analysis, which was facilitated by a risk management consultant. The team consisted of the Technical Services Manager – Underground Operations, the Project Manager, The Undermanager, the Ventilation Officer, a Mining Technician and Fire Officer (representing the underground operators), a ventilation consultant and a coal spontaneous combustion expert. The resulting fault tree has provided the mine with a clear set of controls that can be incorporated into a spontaneous combustion management plan. This approach sets a new benchmark for the coal industry and produces a generic model that is robust enough to be transferable to any mine by adjustment of the site specific parameters. Some of the branches of the fault tree will be presented in this paper to raise the awareness of the coal industry to the comprehensive nature of this approach to risk management.
20110318T09:35:37Z
Beamish, Basil; Sutherland, Tony; Coull, Michael; Walker, David; Day, Gary; Shales, Craig; Cracker, Roger; Rowland, John; Smith, John

Application of genetic algorithms to hypersonic flight control
http://espace.library.uq.edu.au/view/UQ:3067
This paper presents an application of genetic algorithms to the design of a longitudinal flight controller for a hypersonic accelerator vehicle which is to be used to launch small satellites. A feature of hypersonic airbreathing flight vehicles is the high level of engine integration with the airframe. As a result, maintenance of vehicle attitude is not simply an issue of stability, but also one of propulsive effectiveness, which itself varies with flight conditions and the vehicle attitude. There is therefore, limited scope for departure from optimum operating conditions. This, together with the extreme flight conditions, performance uncertainty, and the inherent instability of the vehicle, contributes to a demanding control task. We examine the capacity of a genetic algorithm in designing a fuzzy logic controller for the task of closed loop flight control. With a fixed, present control structure the design task is to configure the control surface through selection of the rule consequents and input scaling. The genetic algorithm uses a collection of simulated flight responses in its formulation of the objective function. This allows the generation of a controller design without linearization of the vehicle model and dynamics. Stability augmentation is shown through flight simulation at the lowspeed end of the hypersonic trajectory and also at a higher flight speed.
20060427T11:06:33Z
Austin, K. J.; Jacobs, P. A.

Application of genetic algorithms to hypesonic flight control
http://espace.library.uq.edu.au/view/UQ:97617
20070824T01:24:24Z
Austin, K.J.; Jacobs, P.A.

Application of high porosity metal foams as aircooled heat exchangers to high heat load removal systems
http://espace.library.uq.edu.au/view/UQ:178858
A numerical study has been conducted to investigate the fluid flow and heat transfer of an aircooled metal foam heat exchanger under the high speed laminar jet confined by two parallel walls for which the range of the Reynolds number is 6001000. Two independent numerical solvers were used and crossvalidated being a FORTRAN code and the commercially available software CFDACE. The effects of local thermal nonequilibrium, thermal dispersion, porosity, and pore density on the heat transfer augmentation are examined for different Reynolds numbers. Application of energy flux vectors, for convection visualization, is also illustrated for a more comprehensive analysis of the problem. Finally, the performance of the metal foam heat exchanger is compared to that of conventional finned design. It is observed that the heat removal rate can be greatly improved at almost no excess cost.
20090701T12:01:53Z
Ejlali, Azadeh; Ejlali, Arash; Hooman, Kamel; Gurgenci, Hal

Application of inlet injection to a threedimensional Scramjet at Mach 8
http://espace.library.uq.edu.au/view/UQ:204329
An investigation of inlet injection in a scramjet having a threedimensional inlet and an elliptical combustion was undertaken. Experiments were conducted using a test flow simulating a Mach 8.1 flight condition with an altitude of 32 km. The objective was to determine the feasibility of reducing the combustionchamber length by injection of hydrogen fuel in the inlet. The study involved a selfstarting threedimensional inlet with an overall geometric contraction ratio of 5.80, of which 2.08 was internal. The fuel was injected through multiple portholes in the forward portion of the inlet to allow significant mixing upstream of the combustion chamber. The divergent elliptical combustion chamber had a length sized for fuel ignition and combustion only and used a fluiddynamic ignition scheme requiring no physical obstructions to the flowpath. Results indicated that inlet injection produced robust combustion at good combustion efficiency over a large fueling range up to an equivalence ratio of 0.92. A further key result was that no evidence of combustion was observed in the inlet. These experiments suggest that fuel injection in the inlet is a promising concept for higherspeed scramjet applications.
20100425T00:06:56Z
Turner, J. C.; Smart, M. K.

Application of leading practice spontaneous combustion assessment to exploration at the Doyles Creek project
http://espace.library.uq.edu.au/view/UQ:310906
20130925T11:14:38Z
Beamish, B.; Cambourn, G.; Lewis, G.; Edman, J.; Beamish, R.

Application Of Linear Fracture Mechanics To Timber Engineering
http://espace.library.uq.edu.au/view/UQ:10065
This paper describes the application of linear elastic fracture mechanics to the design of structural timber members. These include nonzero angle notches, glued lap joints and the butt joints of laminated timber members. The results of this research were used in the development of design rules given in AS 1720, the Australian Timber Engineering Design Code.
20041221T00:00:00Z
Leicester, R. H.

Application of metaheuristic methods to reactive power planning: A comparative study for GA, PSO and EPSO
http://espace.library.uq.edu.au/view/UQ:224805
This paper proposes the application of metaheuristic methods to Reactive Power Planning (RPP). RPP involves optimal allocation of reactive sources to satisfy voltage constraints during normal and contingency states. The main objective of the proposed RPP is to make a tradeoff between economy and security by determining the optimal combination of fast and slow controls (load shedding, new slow and fast VAR devices). The overall problem is formulated as a large scale mixed integer nonlinear programming problem. The proposed RPP problem is a combinatorial optimization problem, which cannot be solved easily by conventional optimization methods. Metaheuristic methods are reported to be efficient to solve combinatorial optimization problems. Among the wellknown metaheuristic methods, this paper discovers the efficiency of Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Evolutionary PSO (EPSO) in solving the proposed RPP problem. The proposed approaches have been successfully tested on IEEE 14 bus system and a comparative study is illustrated.
20101216T09:00:12Z
Eghbal, Mehdi; ElAraby, E. E.; Yorino, Naoto; Zoka, Yoshifumi

Application of metal foams in aircooled condensers for geothermal power plants: An optimization study
http://espace.library.uq.edu.au/view/UQ:243536
Optimized design of metal foam heat exchangers, as replacements for finnedtubes in aircooled condensers of a geothermal power plant, is presented here. Two different optimization techniques, based on first and second law (of thermodynamics) are reported. While the former aims at the highest heat transfer rate with as low pressure drop as possible, the latter minimizes the generated entropy in the thermodynamic system. Interestingly, the two methods lead to the same optimal design. The new design has been compared to the conventional aircooled condenser designed and optimized by using the commercially available software ASPEN. It is shown that while the heat transfer rate increases significantly (by an order of magnitude) compared to the finnedtube for the same main flow obstruction height, the pressure drop increase is within an acceptable range. Further comparison between the two systems are carried out, making use of Mahjoob and Vafai's performance factor developed specifically for metal foam heat exchangers. © 2011 Elsevier Ltd. All rights reserved.
20110711T14:17:00Z
Odabaee, Mostafa; Hooman, Kamel

Application of multiobjective evolutionary optimization algorithms to reactive power planning problem
http://espace.library.uq.edu.au/view/UQ:224809
This paper presents a new approach to treat reactive power (VAr) planning problem using multiobjective evolutionary algorithms (EAs). Specifically, strength Pareto EA (SPEA) and multiobjective particle swarm optimization (MOPSO) approaches have been developed and successfully applied. The overall problem is formulated as a nonlinear constrained multiobjective optimization problem. Minimizing the total incurred cost of the VAr planning problem and maximizing the amount of available transfer capability (ATC) are defined as the main objective functions. The aim is to find the optimal allocation of VAr devices in such a way that investment and operating costs are minimized and at the same time the amount of ATC is maximized. The proposed approaches have been successfully tested on IEEE 14 buses system. As a result a wide set of optimal solutions known as Pareto set is obtained and encouraging results show the superiority of the proposed approaches and confirm their potential to solve such a largescale multiobjective optimization problem.
20101216T09:00:42Z
Eghbal, Mehdi; Yorino, Naoto; Zoka, Yoshifumi; ElAraby, E. E.

Application of Pattern Recognition Approach on Phase I of the IASCASCE Structural Health Monitoring Benchmark Study
http://espace.library.uq.edu.au/view/UQ:175022
20090409T14:57:05Z
Ng, C. T.; Lam, H. F.

Application of phase equilibria to predict the softening behaviour of isp sinters
http://espace.library.uq.edu.au/view/UQ:163193
20090205T16:29:08Z
Zhao, B.; Jak, E.; Hayes, P. C.

Application of pure oxygen for the passivation of mild steel in high temperature and pressure Bayer liquor under conditions of disturbed flow
http://espace.library.uq.edu.au/view/UQ:174474
The passivation characteristics of sulfuric acid cleaned mild steel in spent Bayer liquor (pH 14.4 and 160 degrees C) are examined using a high pressure nickel flow loop. An entrained atmosphere of 99.90% v/v oxygen gas is incorporated as an experimental variable along with Reynolds number (141,700 and 50,950) and intensity of fluid now disturbance. State of passivation has been defined using criteria derived from transient polaristion resistance measurements an largescale polarisation, linear sweep voltammetry. In the majority of cases, oxygenation introduces instantaneous passivation of the mild steel on contact with the Bayer liquor. In comparison to deoxygenated and aerated electrolytes, this rapid rate of passivation can lead to LIP to an order of magnitude reduction in the quantity of charge associated with metal dissolution over 20 h. Although relative rates of corrosion when passive are low and largely independent of the level of flow disturbance, dissolution rates when passive are somewhat larger at the higher Reynolds number. (c) 2008 Elsevier Ltd. All rights reserved.
20090408T09:19:18Z
Kear, G.; Bremhorst, K.

Application of radical farming to a 3D scramjet at Mach 8
http://espace.library.uq.edu.au/view/UQ:193205
20100119T13:55:44Z
Turner, James C.; Smart, Michael K.

Application of rapid prototyping technology
http://espace.library.uq.edu.au/view/UQ:186834
20091118T09:14:30Z
Chen, Bing; Wang, Gui

Application of Real Options in shortterm Mine Planning and Production scheduling
http://espace.library.uq.edu.au/view/UQ:201874
20100407T10:16:43Z
Li, Shuxing; Knights, Peter

Application of SEM/EBSD and FEGTEM/CBED to determine eutectic solidificaation mechanisms
http://espace.library.uq.edu.au/view/UQ:97569
20070824T01:21:21Z
Nogita, K.; Dahle, A. K.; Drennan, J.

Application of shaping filters
http://espace.library.uq.edu.au/view/UQ:101887
20070823T20:30:25Z
Reid, A. W.; Gurgenci, H.

Application of the Bayesian Approach in Crack Detection Utilizing Spatial Wavelet Transform
http://espace.library.uq.edu.au/view/UQ:176379
20090416T15:29:19Z
Lam, H. F.; Ng, C. T.

Application of the modified quasichemical model to solutions with strong shortrange ordering
http://espace.library.uq.edu.au/view/UQ:130119
The present study is concerned with analysis of a specific feature of the modified quasichemical solution model (MQSM). The analyzed feature is typical for binary solutions with very strong shortrange ordering. As demonstrated, a solid compound whose composition coincides with that of maximum ordering in the liquid is required for reasonable representation of phase equilibria in such a system. The limiting slopes of the liquidus curve of the compound are calculated. As a demonstrational example, the thermodynamic model for the system K2OSiO2 with the MQSM for the liquid phase is reoptimized. The new parameters of the thermodynamic model fit the available experimental data and represents reasonable phase relations for the entire compositional range. (c) 2007 Elsevier B.V. All rights reserved.
20080218T15:09:42Z
Saulov, D.N.

Application of wavelet parameters for impact damage detection in plates
http://espace.library.uq.edu.au/view/UQ:295033
In this study, ultrasonic guided waves were used in a laser vibrometer setup to measure impact damage responses in carbon fibre epoxy composite plates. The impact energies used resulted in internal delaminations, as well as small hairline cracks observed on the surface. By identifying a change in the baseline signal compared to the damage response signal and quantitatively characterising it, the impact damages in the specimens could be detected. Damage response could be determined from reflected peaks in the signal arriving after the initial pulse; however, the major difference found was a change in signal amplitude. In order to improve the observation of these changes, wavelet analysis was applied to the signals. Wavelet analysis provided efficient means of removing noise in the signals while allowing for useful data to be extracted from both the time and frequency domains. The maximum wavelet coefficient changes were also easily identified after normalisation to allow for the development of a quantitative index that corresponds to the damage. By relating the absorbed impact energy and the physical damage size to this index parameter, a method of characterising the damage was produced. In general, it was also found that the larger the impact energy and therefore the larger the physical damage area, the greater the calculated value of the Damage Index. This thus provides potential means of quantifying the impact damage in composites with improved efficiency compared to raw signals in the time domain.
20130327T12:50:02Z
Shelley, T. J.; Liew, C. K.

Applications of advanced analytics in process plants: Safer, smarter, sustainable operations
http://espace.library.uq.edu.au/view/UQ:176897
20090417T16:35:38Z
Bassan, J.; Knights, P.

Applications of cavitating waterjets
http://espace.library.uq.edu.au/view/UQ:148523
20080606T14:35:21Z
Meyer, T.; Tadic, D.

Applications of fuzzy logic in multiobjective decision support
http://espace.library.uq.edu.au/view/UQ:149474
20080606T15:33:12Z
Smith, P. N.

Applications of virtual reality in the minerals industry
http://espace.library.uq.edu.au/view/UQ:100068
20070823T19:12:44Z
Kizil, M. S.