Engineering Commons^™

Simplified Models Of Fault Effects On Unitary Air-Conditioning Equipment For Use In Building Simulation Tools, David Yuill, Mehdi Mehrabi

David Yuill

Bayesian Learning And Predictability In A Stochastic Nonlinear Dynamical Model, John Parslow, Noel Cressie, Edward P. Campbell, Emlyn Jones, Lawrence Murray

Professor Noel Cressie

Bayesian inference methods are applied within a Bayesian hierarchical modelling framework to the problems of joint state and parameter estimation, and of state forecasting. We explore and demonstrate the ideas in the context of a simple nonlinear marine biogeochemical model. A novel approach is proposed to the formulation of the stochastic process model, in which ecophysiological properties of plankton communities are represented by autoregressive stochastic processes. This approach captures the effects of changes in plankton communities over time, and it allows the incorporation of literature metadata on individual species into prior distributions for process model parameters. The approach is applied …

Applying A Novel Combination Of Techniques To Develop A Predictive Model For Diabetes Complications, Mohsen Sangi, Khin Than Win, Farid Shirvani, Mohammad-Reza Namazi-Rad, Nagesh Shukla

Nagesh Shukla

No abstract provided.

A Lifetime Individual Sampling Model (Ism) For Heroin Use And Treatment Evaluation In Australia, Nagesh Shukla, Van Hoang, Marian Shahanan, Alison Ritter, Vu Lam Cao, Pascal Perez

Nagesh Shukla

Illicit drug use has created an enormous burden at societal, family and personal levels. Every year a significant amount of resources is allocated for treatment and the consequences of illicit drug use in Australia and around the world. Heroin is one of the major forms of illicit drugs that are used illegally. Several independent heroin treatment strategies or interventions exist and state-of-the-art research demonstrates their efficacy and relative cost-effectiveness. However, assessing total potential gains and burden from providing all treatment interventions or varying the mix of heroin treatments has never been attempted. Furthermore, the need to include multiple treatments, multiple …

A Novel Integrated Model To Measure Supplier Performance Considering Qualitative And Quantitative Criteria Used In The Supplier Selection Process, Alptekin Ulutas, Senevi Kiridena, Peter Gibson, Nagesh Shukla

Nagesh Shukla

Supplier evaluation has become a significant topic over the past few decades, as companies have become more outsourced oriented. However, previous research on this topic has not paid adequate attention to the limitations associated with the availability of accurate and reliable data relating to the performance of potential suppliers. In an attempt to address this issue, this paper proposes a novel supplier evaluation model that can handle imprecise quantitative and qualitative data. Additionally, Decision Maker's judgement regarding both qualitative and quantitative criteria are incorporated into this model so that a more comprehensive and realistic assessment of supplier performance can be …

Fault Diagnosis In Multi-Station Assembly Systems Using An Agent-Based Simulation Model, Nagesh Shukla, Manoj Tiwari, Darek Ceglarek

Nagesh Shukla

Today’s automotive industries require quick ramp-up in order to shorten the time to market and fulfill greater demand for product variety. Since, dimensional tolerance problems are one of the main causes for delay during ramp-up in multi-station assembly systems; hence, rapid diagnosis of faults contributing to dimensional errors is of significant concern. This paper presents an agent-based simulation model (ABSM) which integrates model-based and data-based diagnostics for fault diagnosis and correction in multi-station assembly processes. The fault causing variation sources, their effects on dimensional accuracy, diagnosis from sensors data and corrective actions in multi-station assembly systems are simulated using proposed …

The Impacts Of Climate Change Policies On The Transportation Sector

Faculty of Engineering University of Malaya

This study examines the impact of carbon tax and its alternative, energy tax, on both the Malaysian economy and the transport sector, using a CGE (Computable General Equilibrium) framework. In order to achieve government revenue neutrality, two schemes for revenue recycling, namely lump-sum transfer and labour tax recycling, are employed. The simulation's results show that the carbon tax policy is more effective than the energy tax policy in reducing carbon emissions; because it is less expensive. The negative impact of the carbon tax, on real GDP (Gross Domestic Product) and investment, is less than the energy tax in both recycling …

Stiffness Performance Of Polyethylene Terephthalate Modified Asphalt Mixtures Estimation Using Support Vector Machine-Firefly Algorithm

Faculty of Engineering University of Malaya

Predicting asphalt pavement performance is an important matter which can save cost and energy. To ensure an accurate estimation of performance of the mixtures, new soft computing techniques can be used. In this study, in order to estimate the stiffness property of Polyethylene Terephthalate (PET) modified asphalt mixture, different soft computing methods were developed, namely: support vector machine-firefly algorithm (SVM-FFA), genetic programming (GP), artificial neural network (ANN) and support vector machine. The support vector machine-firefly algorithm (SVM-FFA) is a metaheuristic search algorithm developed according to the socially dashing manners of fireflies in nature. To develop the models, experiments were performed. …

A Multi-Physics Model For Solid Oxide Iron-Air Redox Flow Battery: Simulation Of Discharge Behavior At High Current Density, Meng Guo, Xuan Zhao, Ralph White, Kevin Huang

Kevin Huang

A rigorous physics-based mathematical model for a solid oxide iron-air redox flow battery system is presented in this paper. The modeled flow battery system combines a Fe-FeO redox couple as the energy storage unit and a regenerative solid oxide fuel cell as the electrical functioning unit in a 2D axial symmetric geometry. This model was developed from fundamental theories of reaction engineering in which basic transport phenomena and chemical/electrochemical kinetics are included. The model shows good agreement with the experimental data. Simulation results for the chemical, electrochemical and transport behavior of the battery are discussed.

Application Of Fano Resonance Effects In Optical Antennas Formed By Regular Clusters Of Nanospheres

Faculty of Engineering University of Malaya

This paper describes an analytical model developed to study the Fano resonance effect in clusters of spherical plasmonic nanoparticles under local excitation. The model depicted the case of a parallel single dipole emitter that was near-field coupled to a pentamer or heptamer cluster of nanospheres. Spatial polarization and field distributions of the optical states and resonance spectra for these cluster configurations were calculated. It was discovered that polarization interference between the nanoparticles triggered the formation of a second peak in the directivity spectra at 690 nm, and this in turn provided a mechanism for the occurrence of subradiant mode effects. …

Decision Support System For The Glaucoma Using Gabor Transformation

Faculty of Engineering University of Malaya

Increase in intraocular pressure (IOP) is one of the causes of glaucoma which can lead to blindness if not detected and treated at an early stage. Glaucoma symptoms are not always obvious; hence patients seek treatment only when the condition progressed significantly. Early detection and treatment will decrease the chances of vision loss due to glaucoma. This paper proposes a novel automated glaucoma diagnosis method using various features extracted from Gabor transform applied on digital fundus images. In this work, we have used 510 images to classify into normal and glaucoma classes. Various features namely mean, variance, skewness, kurtosis, energy, …

An Accelerated And Accurate Three-Dimensional Ray Tracing Using Red-Black Tree With Facet Mining And Object Bouncing Techniques

Faculty of Engineering University of Malaya

Recent trends show that it is a major challenge to predict the exact propagation path accurately and efficiently for three-dimensional (3D) indoor environments. Therefore, this study introduces a new 3D ray tracing algorithm based on a red-black tree with facet mining and object bouncing techniques. The red-black tree data structure offers a faster object searching operation while repeatedly performing intersection tests. On the other hand, extensive ray-facet intersection tests can be eliminated by using object and facet bouncing techniques, whereas the facet mining makes it easier to trace the transmitted ray paths accurately. The proposed method is compared with ray …

Conceptual Model Describing Smear Zone Caused By Mandrel Action, Cholachat Rujikiatkamjorn, Made Ardana, Buddhima Indraratna, S Leroueil

Cholachat Rujikiatkamjorn

In this study the characteristics and extent of the smear zone are investigated using a large, undisturbed sample. The aim of using such a sample is to capture the realistic characteristics of the smear zone in relation to the in situ soil structure during the installation of prefabricated vertical drains (PVDs) using a mandrel. The extent of the smear zone for Bulli clay (New South Wales, Australia) is determined on the basis of normalised permeability (k(h)/k(hu)) and the reduction in the water content upon consolidation. The permeability and compressibility of the soil are investigated to determine the extent to which …

Conceptual Model Describing Smear Zone Caused By Mandrel Action, Cholachat Rujikiatkamjorn, Made Ardana, Buddhima Indraratna, S Leroueil

Buddhima Indraratna

In this study the characteristics and extent of the smear zone are investigated using a large, undisturbed sample. The aim of using such a sample is to capture the realistic characteristics of the smear zone in relation to the in situ soil structure during the installation of prefabricated vertical drains (PVDs) using a mandrel. The extent of the smear zone for Bulli clay (New South Wales, Australia) is determined on the basis of normalised permeability (k(h)/k(hu)) and the reduction in the water content upon consolidation. The permeability and compressibility of the soil are investigated to determine the extent to which …

Radial Consolidation Model Incorporating The Effects Of Vacuum Preloading And Non-Darcian Flow, Kourosh Kianfar, Buddhima Indraratna, Cholachat Rujikiatkamjorn

Buddhima Indraratna

A modified 150 mm Rowe cell equipped with pore water pressure measurement was used to capture the flow relationship during vacuum-assisted radial consolidation. Based on the measured data, a radial consolidation model incorporating the effects of vacuum preloading is proposed, based on a non-linear relationship between the flow velocity and hydraulic gradient. The predictions of the proposed consolidation model are then compared with the predictions based on Hansbo’s Darcian and non- Darcian models. The agreement between the proposed model and the measured data is shown, and the advantages of the proposed model compared with the existing models are discussed. An …

Leakage Resilient Authenticated Key Exchange Secure In The Auxiliary Input Model, Guomin Yang, Yi Mu, Willy Susilo, Duncan S. Wong

Professor Willy Susilo

Authenticated key exchange (AKE) protocols allow two parties communicating over an insecure network to establish a common secret key. They are among the most widely used cryptographic protocols in practice. In order to resist key-leakage attacks, several leakage resilient AKE protocols have been proposed recently in the bounded leakage model. In this paper, we initiate the study on leakage resilient AKE in the auxiliary input model. A promising way to construct such a protocol is to use a digital signature scheme that is entropically-unforgeable under chosen message and auxiliary input attacks. However, to date we are not aware of any …

Similarity-Based Search For Model Checking: A Pilot Study With Java Pathfinder, Elmin Ibrahimov, Jixing Wang, Zhiquan Zhou

Dr Zhiquan Zhou

When a model checker cannot explore the entire state space because of limited resources, model checking becomes a kind of testing with an attempt to find a failure (violation of properties) quickly. We consider two state sequences in model checking: (i) the sequence in which new states are generated, and (ii) the sequence in which the states generated in sequence (i) are checked for property violation. We observe that neighboring states in sequence (i) often have similarities in certain ways. Based on this observation we propose a search strategy, which generates sequence (ii) in such a way that similar states …

Experimental Investigation Of The 100 Kev X-Ray Dose Response Of The High-Temperature Thermoluminescence In Lif: Mg, Ti (Tld-100): Theoretical Interpretation Using The Unified Interaction Model, Jayde Livingstone, Y Horowitz, L Oster, H Datz, Michael Lerch, Anatoly Rosenfeld, A Horowitz

Michael L.F. Lerch

The dose response of LiF:Mg,Ti (TLD-100) chips was measured from 1 to 50 000 Gy using 100 keV X rays at the European Synchroton Radiation Facility. Glow curves were deconvoluted into component glow peaks using a computerised glow curve deconvolution (CGCD) code based on first-order kinetics. The normalised dose response, f(D), of glow peaks 4 and 5 and 5b (the major components of composite peak 5), as well as peaks 7 and 8 (two of the major components of the high-temperature thermoluminescence (HTTL) at high levels of dose) was separately determined and theoretically interpreted using the unified interaction model (UNIM). …

An Adaptive Bilateral Negotiation Model Based On Bayesian Learning, Chao Yu, Fenghui Ren, Minjie Zhang

Dr Fenghui Ren

Endowing the negotiation agent with a learning ability such that a more beneficial agreement might be obtained is increasingly gaining attention in agent negotiation research community. In this paper, we propose a novel bilateral negotiation model based on Bayesian learning to enable self-interested agents to adapt negotiation strategies dynamically during the negotiation process. Specifically, we assume that two agents negotiate over a single issue based on time-dependent tactic. The learning agent has a belief about the probability distribution of its opponent's negotiation parameters (i.e., the deadline and reservation offer). By observing opponent's historical offers and comparing them with the fitted …

An Investigation On The Impacts Of Density Currents On The Sedimentation In Dam Reservoirs Using Tcm Model; Case Study: Maroon Dam, Farhad Raof, Mohammad Naghshine, Ali Khoshrftar

Farhad Fakheri Raof

Sedimentation in dams' reservoirs is one of the most pressing concerns facing dams today. Maroon reservoir dam, located in Khuzestan Province, is one of the most important dams in this region. Since it is a new constructed dam, numerical simulation of sedimentation trend in its reservoirs could significantly help on a better utilization. To this end, TCM model which is capable to simulate density currents was used. The obtained results show that the dam loses about 91 million m3 of its reservoirs during a 50-year exploitation period.

Shear Strength Model For Sediment-Infilled Rock Discontinuities And Field Applications, Buddhima Indraratna, Wuditha N. Premadasa, Jan Anton Nemcik, Mylvaganam Jayanathan

Wuditha N Premadasa

Discontinuities have a great influence on the reduction of rock mass shear strength depending on the geometry, roughness and the nature of infill sediments. These discontinuities are generally filled with different types of sediments. When the infill sediments are saturated, they make a considerable impact on the overall strength of the rock mass. Most infilled discontinuities in the field are overconsolidated due to various factors such as climatic and weathering conditions, as well as hydrothermal alteration. The increase in the thickness of joint infill subdues the otherwise prominent role of joint roughness. This paper presents some of the existing mathematical …

Studying The Impact Of The Corner Propagation Model On Vanet Routing In Urban Environments, Abhinay Mukunthan, Craig Cooper, Farzad Safaei, D. Franklin, Mehran Abolhasan

Professor Farzad Safaei

Accurate modelling of the radio channel is often the most difficult aspect of a Vehicular Ad Hoc Network (VANET) simulation due to the large variability present in vehicular terrain. CORNER is a propagation model that calculates path-loss in an urban terrain with a large concentration of buildings, based on the position of the transmitter and receiver on a street map. This paper proposes additions to the CORNER propagation model to take selective multi-path fading into account and investigates the performance of the GPSR routing protocol under the CORNER propagation model in a realistic city environment.

Ignoring A Level In A Multilevel Model: Evidence From Uk Census Data, Mark Tramner, David Steel

Professor David Steel

Because of the inherent multilevel nature of census data, it is often appropriate to use multilevel models to investigate relationships between census variables. For a local population, the data available from the census allow a three-level nested model to be assumed, with an individual level (level 1), an enumeration district (ED) level (level 2), and a ward level (level 3). The consequences of ignoring one of the three levels in this model are assessed here theoretically. Empirical results, based on 1991 UK Census data, are also provided, comparing the variance components estimated from the three-level model with analyses based on …

An Introduction To Model-Based Survey Sampling With Applications, Raymond Chambers, Robert Clark

Robert Clark

No abstract provided.

Levetiracetam-Loaded Biodegradable Polymer Implants In The Tetanus Toxin Model Of Temporal Lobe Epilepsy In Rats, Amy J. Halliday, Toni E. Campbell, Timothy S. Nelson, Karen J. Mclean, Gordon G. Wallace, Mark J. Cook

Gordon Wallace

Approximately one-third of people with epilepsy receive insufficient benefit from currently available anticonvulsant medication, and some evidence suggests that this may be due to a lack of effective penetration into brain parenchyma. The current study investigated the ability of biodegradable polymer implants loaded with levetiracetam to ameliorate seizures following implantation above the motor cortex in the tetanus toxin model of temporal lobe epilepsy in rats. The implants led to significantly shorter seizures and a trend towards fewer seizures for up to 1 week. The results of this study indicate that drug-eluting polymer implants represent a promising evolving treatment option for …

Simulation Model Of A Grid-Connected Single-Phase Photovoltaic System In Pscad/Emtdc, Brian K. Perera, Sridhar R. Pulikanti, Philip Ciufo, Sarath Perera

Dr Philip Ciufo

In this paper, a complete simulation model of a grid-connected single-phase two-stage photovoltaic (PV) system with associated controllers is presented. The simulation model is developed in PSCAD/EMTDC simulation program. The component models of the grid-connected PV system include a PV array, a dc-dc boost converter, a voltage source converter (VSC) and an LCL filter. Components of the LCL filter, the dc-link capacitor of the VSC and the inductor of the dc-dc boost converter are established theoretically and that are used in modelling the grid-connected PV system. The control architecture of the presented system incorporates a synchronous reference frame phase-locked-loop (s-PLL), …

Integrated Seat And Suspension Control For A Quarter Car With Driver Model, Haiping Du, Weihua Li, Nong Zhang

Professor Weihua Li

In this paper, an integrated vehicle seat and sus pension control strategy for a quarter car with driver model is proposed to improve suspension performance on driver ride comfort. An integrated seat and suspension model that includes a quarter-car suspension, a seat suspension, and a 4-degree-of freedom (DOM) driver body model is presented first. This in1 tegrated model provides a platform to evaluate ride comfort 1performance in terms of driver head acceleration responses under typical road disturbances and to develop an integrated control of seat and car suspensions. Based on the integrated model, an H∞ state feedback controller is designed …

A Microslip Model Of The Bonding Process In Ultrasonic Wire Bonders Part I: Transient Response, C M. Hu, N Guo, H Du, W H. Li, M Chen

Professor Weihua Li

Ultrasonic wire bonders with precision capillary tips are widely used for bonding electrical wires to IC chips and circuits. The industry is driving wire-bonding technology towards increased yields, decreased pitch, and ever decreasing cost. However, many technical and material issues will be involved in achieving these goals, such as bond quality monitoring, new failure modes, reliability problems in new plastic mold compounds, and increasing wire sweep problems, in particular lack of the quantitative understanding and validated mathematical model of the bonding process. In this paper, a microslip model is proposed for the bonding process based on the bonding pattern observed, …

A Novel Model To Measure Supplier Performance In The Supplier Selection Process, Alptekin Ulutas, Senevi Kiridena, Peter Gibson

Peter R Gibson

Supplier evaluation has become a significant topic over the past decades, as companies have started to become more outsourced oriented. However, previous research on this topic has not paid adequate attention to the limitations associated with availability of accurate and reliable data relating to the performance of potential suppliers. In an attempt to address this issue, this paper proposes a novel supplier evaluation model that can handle imprecise quantitative and qualitative data. Additionally, Decision Maker’s opinions regarding both qualitative and quantitative criteria are incorporated into this model so that a more comprehensive and realistic assessment of supplier performance can be …

Indoor Localisation Using A Context-Aware Dynamic Position Tracking Model, Montserrat Ros, Joshua Boom, Gavin De Hosson, Matthew D'Souza

Dr Montserrat Ros

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Indoor wireless localisation is a widely sought feature for use in logistics, health, and social networking applications. Low-powered localisation will become important for the next generation of pervasive media applications that operate on mobile platforms. We present an inexpensive and robust context-aware tracking system that can track the position of users in an indoor environment, using a wireless smart meter network. Our context-aware tracking system combines wireless trilateration with a …