Engineering Commons^™

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

David Yuill

Sludge Cycling Between Aerobic, Anoxic And Anaerobic Regimes To Reduce Sludge Production During Wastewater Treatment: Performance, Mechanisms, And Implications, Galilee Semblante, Faisal Ibney Hai, Huu H. Ngo, Wenshan Guo, Sheng-Jie You, William Price, Long Nghiem

Faisal I Hai

Alternate cycling of sludge in aerobic, anoxic, and anaerobic regimes is a promising strategy that can reduce the sludge yield of conventional activated sludge (CAS) by up to 50% with potentially lower capital and operating cost than physical- and/or chemical-based sludge minimisation techniques. The mechanisms responsible for reducing sludge yield include alterations to cellular metabolism and feeding behaviour (metabolic uncoupling, feasting/fasting, and endogenous decay), biological floc destruction, and predation on bacteria by higher organisms. Though discrepancies across various studies are recognisable, it is apparent that sludge retention time, oxygen-reduction potential of the anaerobic tank, temperature, sludge return ratio and loading …

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 …

Performance Of Adjustable Speed Drives Subject To Regular Voltage Fluctuations, Kun Zhao, Philip Ciufo, Sarath Perera

Dr Philip Ciufo

The impact of power quality disturbances on customer equipment has been a topic of interest to equipment manufacturers, electricity utilities, customers and to those involved in the development of electromagnetic compatibility standards. Recently, a new interest has developed in the possible impact of voltage fluctuations on customer equipment because of suggestions to relax voltage fluctuation limits and hence the flicker limits in power systems. With a view to contribute to this understanding, this paper investigates the performance of an adjustable speed drive (ASD) when subjected to sinusoidal regular voltage fluctuations. When the ASD is operating in open loop mode, the …

Human Performance Engineering Approach, Dotan I. Shvorin

Dr. Dotan Shvorin

Joint Map Registration And High Resolution Image Estimation Using A Sequence Of Undersampled Images, Russell C. Hardie, Kenneth J. Barnard, Ernest E. Armstrong

Russell C. Hardie

n many imaging systems, the detector array is not sufficiently dense to adequately sample the scene with the desired field of view. This is particularly true for many infrared focal plane arrays. Thus, the resulting images may be severely aliased. This paper examines a technique for estimating a high-resolution image, with reduced aliasing, from a sequence of undersampled frames. Several approaches to this problem have been investigated previously. However, in this paper a maximum a posteriori (MAP) framework for jointly estimating image registration parameters and the high-resolution image is presented. Several previous approaches have relied on knowing the registration parameters …

Performance Of Solid Oxide Iron-Air Battery Operated At 550°C, Xuan Zhao, Yunhui Gong, Xue Li, Nansheng Xu, Kevin Huang

Kevin Huang

“Metal-air” batteries have garnered much attention in recent years due to their high intrinsic specific energy and use of inexhaustible and storage-free oxygen source -air- for the “metal-oxygen” reaction. In this study, we report theperformance of a new type of all solid-state “iron-air” battery operated at 550°C. The results show that CeO2 nanoparticles incorporated into the Fe-Fe3O4 redox-couple can improve the specific energy (Wh/kg) and round trip efficiency by 15% and 29%, respectively, over the baseline Fe-Fe3O4 battery. Use of supported Fe-Fe3O4 nanoparticles as the redox couple can increase the specific energy and round-trip efficiency by 13% and 48% over …

Superior Perovskite Oxide-Ion Conductor; Strontium- And Magnesium-Doped Lagao3: Iii, Performance Tests Of Single Ceramic Fuel Cells, Kevin Huang, Robin Tichy, John Goodenough, Christopher Milliken

Kevin Huang

No abstract provided.

Performance Of Vapor-Fed Direct Dimethyl Ether Fuel Cell Utilizing High Temperature Polybenzimidazole Polymer Electrolyte Membrane, Jay Neutzler, Guoging Qian, Kevin Huang, Brian Benicewicz

Kevin Huang

No abstract provided.

Affect Classification Using Genetic-Optimized Ensembles Of Fuzzy Artmaps

Faculty of Engineering University of Malaya

Training neural networks in distinguishing different emotions from physiological signals frequently involves fuzzy definitions of each affective state. In addition, manual design of classification tasks often uses sub-optimum classifier parameter settings, leading to average classification performance. In this study, an attempt to create a framework for multi-layered optimization of an ensemble of classifiers to maximize the system's ability to learn and classify affect, and to minimize human involvement in setting optimum parameters for the classification system is proposed. Using fuzzy adaptive resonance theory mapping (ARTMAP) as the classifier template, genetic algorithms (GAs) were employed to perform exhaustive search for the …

Influences Of Flame-Retardant Fillers On Fire Protection And Mechanical Properties Of Intumescent Coatings

Faculty of Engineering University of Malaya

A combination of acrylic binder and flame-retardant ingredients was used to synthesize the solvent-borne intumescent coatings designed for steel substrates. The influences of individual and various combinations of flame-retardant fillers on the fire protection and mechanical properties of the coatings were characterized by using Bunsen burner, thermogravimetric analysis, limiting oxygen index, field emission scanning electron microscopy, freeze thaw cycles, static immersion and pull-off type equipment. It was found that the combination of aluminium hydroxide (Al(OH)(3)) and titanium dioxide (TiO2) has significantly improved the fire protection, thermal stability and water resistance of the coating. This formulation had an LOI value of …

High Performance Pure Sulfur Honeycomb-Like Architectures Synthesized By A Cooperative Self-Assembly Strategy For Lithium Sulfur Batteries, Xin Liang, Mohammad Kaiser, Konstantin Konstantinov, Richard Tandiono, Zhaoxiang Prof Zhaoxiang Wang, Hua-Kun Liu, S X. Dou, Jiazhao Wang

Shi Xue Dou

Honeycomb-like pure sulfur architectures were synthesized by a cooperative self-assembly strategy, in which a soft template is used to form the porous structure. Their electrochemical performance is significantly improved comparing with the commercial sulfur powder and the as-prepared sulfur without honeycomb morphology. There has been no report on using a soft template to prepare honeycomb-like sulfur particles.

Thermoelectric Performance Of N-Type (Pbte)0.75(Pbs)0.15(Pbse)0.1 Composites, Sima Aminorroaya Yamini, Heng Wang, Dianta Ginting, David R. G Mitchell, S X. Dou, G. Jeffrey Snyder

Shi Xue Dou

Lead chalcogenides (PbQ, Q = Te, Se, S) have proved to possess high thermoelectric efficiency for both n-type and p-type compounds. Recent success in tuning of electronic band structure, including manipulating the band gap, multiple bands, or introducing resonant states, has led to a significant improvement in the thermoelectric performance of p-type lead chalcogenides compared to the n-type ones. Here, the n-type quaternary composites of (PbTe)0.75(PbS)0.15(PbSe)0.1 are studied to evaluate the effects of nanostructuring on lattice thermal conductivity, carrier mobility, and effective mass variation. The results are compared with the similar ternary systems of (PbTe)1-x(PbSe)x, (PbSe) 1-x(PbS)x, and (PbS)1-x(PbTe)x. The …

Thermoelectric Performance Of Tellurium-Reduced Quaternary P-Type Lead-Chalcogenide Composites, Sima Aminorroaya Yamini, Heng Wang, Zachary M. Gibbs, Yanzhong Pei, David R. G Mitchell, S X. Dou, G. Jeffrey Snyder

Shi Xue Dou

A long-standing technological challenge to the widespread application of thermoelectric generators is obtaining high-performance thermoelectric materials from abundant elements. Intensive study on PbTe alloys has resulted in a high figure of merit for the single-phase ternary PbTe-PbSe system through band structure engineering, and the low thermal conductivity achieved due to nanostructuring leads to high thermoelectric performance for ternary PbTe-PbS compounds. Recently, the single-phase p-type quaternary PbTe-PbSe-PbS alloys have been shown to provide thermoelectric performance superior to the binary and ternary lead chalcogenides. This occurs via tuning of the band structure and from an extraordinary low thermal conductivity resulting from high-contrast …

High-Performance Sodium-Ion Batteries And Sodium-Ion Pseudocapacitors Based On Mos2/Graphene Composites, Yunxiao Wang, Shulei Chou, David Wexler, Hua-Kun Liu, S X. Dou

Shi Xue Dou

Sodium-ion energy storage, including sodium-ion batteries (NIBs) and electrochemical capacitive storage (NICs), is considered as a promising alternative to lithium-ion energy storage. It is an intriguing prospect, especially for large-scale applications, owing to its low cost and abundance. MoS2 sodiation/desodiation with Na ions is based on the conversion reaction, which is not only able to deliver higher capacity than the intercalation reaction, but can also be applied in capacitive storage owing to its typically sloping charge/discharge curves. Here, NIBs and NICs based on a graphene composite (MoS2/G) were constructed. The enlarged d-spacing, a contribution of the graphene matrix, and the …

Ultra-High Performance, High-Temperature Superconducting Wires Via Cost-Effective, Scalable, Co-Evaporation Process, Ho-Sup Kim, Sang-Soo Oh, Hong-Soo Ha, Dojun Youm, Seung-Hyun Moon, Jung Ho Kim, S X. Dou, Yoon-Uk Heo, Sung-Hun Wee, Amit Goyal

Shi Xue Dou

Long-length, high-temperature superconducting (HTS) wires capable of carrying high critical current, Ic, are required for a wide range of applications. Here, we report extremely high performance HTS wires based on 5 μm thick SmBa2Cu3O7 − δ (SmBCO) single layer films on textured metallic templates. SmBCO layer wires over 20 meters long were deposited by a cost-effective, scalable co-evaporation process using a batch-type drum in a dual chamber. All deposition parameters influencing the composition, phase, and texture of the films were optimized via a unique combinatorial method that is broadly applicable for co-evaporation of other promising complex materials containing several cations. …

Performance Monitoring Of A Permeable Reactive Barrier (Prb) For The Remediation Of Acidic Groundwater In Acidic Sulfate Soil (Ass) Terrain, Laura Banasiak, Buddhima Indraratna

Laura J Banasiak Dr

The treatment of acidic drainage contaminated with potentially toxic metals such as dissolved aluminium (Al) and iron (Fe) resulting from pyrite oxidation in acid sulfate soil (ASS) is a challenging problem requiring novel engineering solutions. Traditional remediation techniques of lime neutralization, groundwater manipulation (e.g. fixed-level weirs), tidal buffering (e.g. modified floodgates) are unsuitable due to their inherent inability to prevent pyrite oxidation and treat acid previously generated, as well as the risk of flooding during heavy rainfall events. As an alternative, the first permeable reactive barrier (PRB) with recycled concrete aggregates as the reactive material was installed in 2006 in …

Performance And Prediction Of Surcharge And Vacuum Consolidation Via Prefabricated Vertical Drains With Special Reference To Highways, Railways And Ports, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Xueyu Geng

Cholachat Rujikiatkamjorn

Much of the world’s essential infrastructure is built along congested coastal belts that are composed of highly compressible and weak soils up to significant depths. Soft alluvial and marine clay deposits have very low bearing capacity and excessive settlement characteristics, with obvious design and maintenance implications on tall structures and large commercial buildings, as well as port and transport infrastructure. Stabilising these soft soils before commencing construction is essential for both long term and short term stability. A system of vertical drains combined with vacuum pressure and surcharge preloading has become an attractive ground improvement alternative in terms of both …

Performance And Prediction Of Marine Clay Treated With Vacuum And Surcharge Consolidation At Port Of Brisbane, Buddhima Indraratna, A S. Balasubramaniam, Harry Poulos, Cholachat Rujikiatkamjorn, Jayantha Ameratunga

Cholachat Rujikiatkamjorn

During the past decade, the application of vacuum preloading for stabilising soft coastal clay and other low-lying estuarine soils has become popular in Australia. The cost-effectiveness isa major factor in most projects in view of the significantly reduced time for achieving high degree of consolidation. Due to an increase in trade activities at the Port of Brisbane, new facilities on Fisherman Islands at the mouth of the Brisbane River will be constructed on the new outer area (235 ha) adjacent to the existing port facilities via land reclamation. A vacuum assited surcharge load and conventional surcharge scheme in conjunction with …

Track Stabilisation With Geosynthetics And Geodrains, And Performance Verification Through Field Monitoring And Numerical Modelling, Buddhima Indraratna, S Nimbalkar, Cholachat Rujikiatkamjorn

Cholachat Rujikiatkamjorn

All over the world, ballasted railway tracks form one of the major transportation networks designed to provide heavy haul freight and passenger traffic. However, large cyclic loading from heavy axle trains operating at high speeds often causes excessive deformation and degradation of ballast, as well as unacceptable differential settlement of compressible foundation and, or pumping of the soft subgrade soils. The problem becomes more severe under high impact loads due to rail or wheel imperfections, causing accelerated ballast breakage. A proper understanding of load transfer mechanisms and their effects on track deformations are essential prerequisites for minimising maintenance costs. The …

Effects Of Geosynthetic Reinforcement On Performance Of Ballasted Rail Track, Pongpipat Anantanasakul, Buddhima Indraratna, Sanjay S. Nimbalkar, Tim Neville

Buddhima Indraratna

The 'field' performance of different geosynthetics to reinforce ballasted rail tracks was investigated. An extensive monitoring program was undertaken on fully instrumented track sections constructed near Singleton, New South Wales. Four types of geosynthetics were installed at the ballast-subballast interface of track sections located on subgrades with three distinctly different values of stiffness. It was found that geogrids could decrease vertical settlements of the ballast layer with obvious benefits of improved track stability and decreased maintenance cost. It was also found that the effectiveness of reinforcing geogrids increased when the subgrade stiffness decreased. Keywords: Geosynthetic, Reinforcement, Rail track, Ballast.

Performance And Prediction Of Marine Clay Treated With Vacuum And Surcharge Consolidation At Port Of Brisbane, Buddhima Indraratna, A S. Balasubramaniam, Harry Poulos, Cholachat Rujikiatkamjorn, Jayantha Ameratunga

Buddhima Indraratna

During the past decade, the application of vacuum preloading for stabilising soft coastal clay and other low-lying estuarine soils has become popular in Australia. The cost-effectiveness isa major factor in most projects in view of the significantly reduced time for achieving high degree of consolidation. Due to an increase in trade activities at the Port of Brisbane, new facilities on Fisherman Islands at the mouth of the Brisbane River will be constructed on the new outer area (235 ha) adjacent to the existing port facilities via land reclamation. A vacuum assited surcharge load and conventional surcharge scheme in conjunction with …

Performance And Prediction Of Vacuum Combined Surcharge Consolidation At Port Of Brisbane, Buddhima Indraratna, Jayantha Ameratunga, Cholachat Rujikiatkamjorn, Harry G. Poulos, A S. Balasublamaniam

Buddhima Indraratna

During the past decade, the application of vacuum pressure for stabilising soft coastal clay and other low-lying estuarine soils has become increasingly popular in Australia, mainly due to the proven costeffectiveness in view of the significantly reduced time for achieving a high degree of consolidation and enhanced shear strength. Due to an increase in trade activities at the Port of Brisbane, new facilities on Fisherman Islands at the mouth of the Brisbane River will be constructed on the new outer area (235ha) adjacent to the existing port facilities via land reclamation. A scheme of vacuum assisted surcharge load in conjunction …

Field Monitoring Of Performance Of Ballasted Rail Track With Geosynthetic Reinforcement, P Anantanasakul, B Indraratna, S S. Nimbalkar, T Neville

Buddhima Indraratna

Large cyclic stresses induced from heavy traffic can cause significant degradation of rail tracks, leading to poor track geometry and safety. Inclusion of resilient materials such as geosynthetics to reinforce the track substructure has been observed in the laboratory to be viable at reducing the impact of such adverse effects. Despite this, the ‘field’ performance of different geosynthetics to reinforce ballasted tracks has not been investigated in a systematic manner. An extensive field study was therefore undertaken on experimental track sections near Singleton, New South Wales. Four types of geosynthetics were installed at the ballast-subballast interface of track sections constructed …

Track Stabilisation With Geosynthetics And Geodrains, And Performance Verification Through Field Monitoring And Numerical Modelling, Buddhima Indraratna, S Nimbalkar, Cholachat Rujikiatkamjorn

Buddhima Indraratna

All over the world, ballasted railway tracks form one of the major transportation networks designed to provide heavy haul freight and passenger traffic. However, large cyclic loading from heavy axle trains operating at high speeds often causes excessive deformation and degradation of ballast, as well as unacceptable differential settlement of compressible foundation and, or pumping of the soft subgrade soils. The problem becomes more severe under high impact loads due to rail or wheel imperfections, causing accelerated ballast breakage. A proper understanding of load transfer mechanisms and their effects on track deformations are essential prerequisites for minimising maintenance costs. The …

Aqueous Dispersions Of Reduced Graphene Oxide And Multi Wall Carbon Nanotubes For Enhanced Glucose Oxidase Bioelectrode Performance, Willo Grosse, Joffrey Champavert, Sanjeev Gambhir, Gordon G. Wallace, Simon E. Moulton

Gordon Wallace

Aqueous dispersions of reduced graphene oxide (rGO) and multi walled carbon nanotubes (MWCNT) were fabricated through a modified chemical reduction method. The significant advantage of the method developed here is the omission of any stabilising compound or organic solvent to obtain stable rGO-MWCNT dispersions. Significantly biological entities, in this case the enzyme glucose oxidase (GOx), can be successfully incorporated into the dispersion. These dispersions were characterised using XPS, SEM, zeta potential and particle size measurements which showed that the dispersion stability is not sacrificed with the addition of GOx, and significantly, the electrical properties of the rGO and MWCNTs are …

Evaluation Of Encapsulating Coatings On The Performance Of Polypyrrole Actuators, Sina Naficy, Nicholas Stoboi, Philip G. Whitten, Geoffrey M. Spinks, Gordon G. Wallace

Gordon Wallace

Conjugated polymer actuators are electroactive materials capable of generating force and movement in response to an applied external voltage. Many potential biomedical and industrial applications require these actuators to operate in a liquid environment. However, immersion of uncoated conducting polymer actuators in non-electrolyte liquids greatly reduces their operating lifetime. Here, we demonstrate the use of spray coating as an effective and simple method to encapsulate polypyrrole (PPy) tri-layer bending actuators. Poly(styrene-b-isobutylene-b-styrene) (SIBS) was used as an encapsulating, compliant spray coating on PPy actuators. A significant enhancement in actuator lifetime in both air and water was observed by encapsulating the actuators. …

Cation Exchange At Semiconducting Oxide Surfaces: Origin Of Light-Induced Performance Increases In Porphyrin Dye-Sensitized Solar Cells, Matthew J. Griffith, Kenji Sunahara, Akihiro Furube, Attila J. Mozer, David L. Officer, Pawel Wagner, Gordon G. Wallace, Shogo Mori

Gordon Wallace

The origin of simultaneous improvements in the short-circuit current density (Jsc) and open-circuit voltage (Voc) of porphyrin dye-sensitized TiO2 solar cells following white light illumination was studied by systematic variation of several different device parameters. Reduction of the dye surface loading resulted in greater relative performance enhancements, suggesting open space at the TiO2 surface expedites the process. Variation of the electrolyte composition and subsequent analysis of the conduction band potential shifts suggested that a light-induced replacement of surface-adsorbed lithium (Li+) ions with dimethylpropylimidazolium (DMPIm+) ions was responsible for an increased electron lifetime by decreasing the recombination with the redox mediator. …

A Facile Route To Synthesize Transition Metal Oxide/Reduced Graphene Oxide Composites And Their Lithium Storage Performance, Chongjun Zhao, Shulei Chou, Yunxiao Wang, Cuifeng Zhou, Hua-Kun Liu, S X. Dou

Shi Xue Dou

Transition metal oxide (Mn3O4, Fe2O3, Co3O4, and ZnO) and reduced graphene oxide (RGO) composites were successfully synthesized via a hydrothermal method using the direct reaction between the corresponding metal powder and graphene oxide (GO). In this process, the GO can be reduced by transition metal powder in water, and the nanosized metal oxide can be obtained, and homogeneously mixed with and wrapped by RGO to form a metal oxide/RGO composite at the same time. X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning and transmission electron microscopy were used to characterize the as-prepared materials. The different experimental parameters, including reactants, …

Synergetic Combination Of Limd With Chpd For The Production Of Economical And High Performance Mgb2 Wires, Minoru Maeda, Md Shahriar Ai Hossain, Ashkan Motaman, Jung Ho Kim, Anna Kario, Matt Rindfleisch, Mike Tomsic, S X. Dou

Shi Xue Dou

We propose an economical fabrication concept, the localized internal magnesium diffusion (IMD) method. Instead of using a single magnesium (Mg) rod in the center of a metal sheath tube, we use large-sized Mg particles (20-50 mesh) mixed well with cheap 97% crystalline boron powder to fill the metal sheath tube. After a repeated drawing process, the coarse Mg is elongated along the core wire axis of the metal sheath tube. Textured MgB2 grains are then formed during the sintering process. In the localized IMD process, however, there is still a need to improve the overall density. In order to increase …