Engineering Commons^™

Development Of A Mix Design Adjustment Method For Fiber Reinforced Concrete And Super High Performance Concrete Based On Excess Paste, Joe Malloy

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The main objective of this study was to develop a mix design adjustment method for Fiber Reinforced Concrete (FRC) that would maintain appropriate workability while improving hardened concrete performance. A literature review was conducted to examine existing methods for adjusting mix designs to account for fiber introduction. It was found that while increasing fine aggregate and cement paste content can make up for lost workability with the addition of fibers, no rational mix design adjustment method is available. Reference mix designs from the Nevada Department of Transportation and the Nebraska Department of Transportation were used, and this study focused on …

On I/O Performance And Cost Efficiency Of Cloud Storage: A Client's Perspective, Binbing Hou

LSU Doctoral Dissertations

Cloud storage has gained increasing popularity in the past few years. In cloud storage, data are stored in the service provider’s data centers; users access data via the network and pay the fees based on the service usage. For such a new storage model, our prior wisdom and optimization schemes on conventional storage may not remain valid nor applicable to the emerging cloud storage.

In this dissertation, we focus on understanding and optimizing the I/O performance and cost efficiency of cloud storage from a client’s perspective. We first conduct a comprehensive study to gain insight into the I/O performance behaviors …

A Framework To Predict The Dewatering Performance Of Large Scale Geotextile Tubes In The Field, Chinthoory Ganesalingam

Theses - ALL

Over the past two decades, geotextile tube dewatering technology has been widely used to handle high water content waste materials in a more sustainable and economical way. The function of a geotextiles tube in a dewatering project is to retain the solid particles inside the tube and release the effluent from the tube through the pores in its surface. Several small-scale (Pressure Filtration Test – PFT, Falling Head Test – FHT) and medium-scale (Geotextile Tube Dewatering Test – GDT, Hanging Bag Test – HBT) performance tests are available to predict the results of the geotextile tube dewatering process in the …

Simulation Of Blade Tip Grooving Effect On Performance Of Twin-Stage Variable-Pitch Axial Fan, Xuemin Ye, Jiankun Zhang, Chunxi Li

Journal of System Simulation

Abstract: For a twin-stage variable-pitch axial fan, a novel blade tip treatment carving a chute from the pressure side to suction side is proposed, and fan performance under different blade tip treatments is simulated to determine the excellent treatment. The effects of blade tip grooving in a single stage or both stages on fan performance and internal dynamics are examined. Numerical results show that both blade tip treatments can improve the fan performance; the overall promotion of fan performance illustrates that the best scheme is the blade tip grooving in the first stage followed by the blade tip grooving …

Improved Performance Of Ballasted Tracks Under Impact Loading By Recycled Rubber Mats, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn

Faculty of Engineering and Information Sciences - Papers: Part B

Ballasted tracks at transition locations such as approaches to bridges and road crossings experience increasing degradation and deformation due to dynamic and high impact forces, a key factor that decreases the stability and longevity of railroads. One solution to minimise ballast degradation at the transition zones is using rubber energy absorbing drainage sheets (READS) manufactured from recycled tyres. When placed beneath the ballast layer, READS distributes the load over wider area and attenuate of the load over a longer duration thus decreasing maximum stress, apart from reducing the energy transferred to the ballast and other substructure components. Subsequently, the track …

Use Of Geogrids And Recycled Rubber In Railroad Infrastructure For Enhanced Performance, Buddhima Indraratna, Yujie Qi, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn, Tim Neville, Fernanda Bessa Ferreira, Amir Shahkolahi

Faculty of Engineering and Information Sciences - Papers: Part B

Railway tracks are conventionally built on compacted ballast and structural fill layers placed above the natural (subgrade) foundation. However, during train operations, track deteriorations occur progressively due to ballast degradation. The associated track deformation is usually accompanied by a reduction in both load bearing capacity and drainage, apart from imposing frequent track maintenance. Suitable ground improvement techniques involving plastic inclusions (e.g., geogrids) and energy absorbing materials (e.g., rubber products) to enhance the stability and longevity of tracks have become increasingly popular. This paper presents the outcomes from innovative research and development measures into the use of plastic and rubber elements …

Performance Evaluation Of Intermittently Cfrp Wrapped Square And Circularised Square Reinforced Concrete Columns Under Different Loading Conditions, Anh Duc Mai, M Neaz Sheikh, Muhammad N. S Hadi

Faculty of Engineering and Information Sciences - Papers: Part B

This paper presents the results of an experimental investigation on square and circularised square rein-forced concrete (RC) columns intermittently wrapped with carbon fibre reinforced polymer (CFRP)under different loading conditions. Twelve RC specimens consisting of eight square RC specimenswith 150mm150mm cross-section and 800mm height and four circularised square RC specimenswith 212mm diameter and 800 mm height were tested under concentric axial load, eccentric axialload and four-point flexural load. The test results showed that intermittent wrapping increased thestrength and ductility of square RC specimens. The test results also showed that circularisation com-bined with intermittent wrapping significantly improved the strength and ductility of …

Structure And Electrochemical Performance Modulation Of A Lini0.8co0.1mn0.1o2 Cathode Material By Anion And Cation Co-Doping For Lithium Ion Batteries, Rong Li, Yong Ming, Wei Xiang, Chunliu Xu, Guilin Feng, Yongchun Li, Yanxiao Chen, Zhenguo Wu, Ben-He Zhong, Xiaodong Guo

Australian Institute for Innovative Materials - Papers

Ni-rich layered transition metal oxides show great energy density but suffer poor thermal stability and inferior cycling performance, which limit their practical application. In this work, a minor content of Co and B were co-doped into the crystal of a Ni-rich cathode (LiNi0.8Co0.1Mn0.1O2) using cobalt acetate and boric acid as dopants. The results analyzed by XRD, TEM, XPS and SEM reveal that the modified sample shows a reduced energy barrier for Li+ insertion/extraction and alleviated Li+/Ni2+ cation mixing. With the doping of B and Co, corresponding enhanced cycle stability was achieved with a high capacity retention of 86.1% at 1.0C …

Performance Evaluation Of Non-Gps Based Localization Techniques Under Shadowing Effects, Ngoc M. Nguyen, Le Chung Tran, Farzad Safaei, Son Lam Phung, Peter James Vial, Nam N. Huynh, Anne N. Cox, Theresa Harada, Johan Barthelemy

Faculty of Engineering and Information Sciences - Papers: Part B

Non-GPS localization has gained much interest from researchers and industries recently because GPS might fail to meet the accuracy requirements in shadowing environments. The two most common range-based non-GPS localization methods, namely Received Signal Strength Indicator (RSSI) and Angle-of-Arrival (AOA), have been intensively mentioned in the literature over the last decade. However, an in-depth analysis of the weighted combination methods of AOA and RSSI in shadowing environments is still missing in the state-of-the-art. This paper proposes several weighted combinations of the two RSSI and AOA components in the form of pAOA + qRSSI, devises the mathematical model for analyzing shadowing …

Frequency Domain Characterization And Performance Bounds Of Alms Loop For Rf Self-Interference Cancellation, Anh Tuyen Le, Le Chung Tran, Xiaojing Huang, Y J. Guo, J (Yiannis) Vardaxoglou

Faculty of Engineering and Information Sciences - Papers: Part B

Analog Least Mean Square (ALMS) loop is a promising method to cancel self-interference (SI) in in-band fullduplex (IBFD) systems. In this paper, the steady state analyses of the residual SI powers in both analog and digital domains are firstly derived. Eigenvalue decomposition is then utilized to investigate the frequency domain characteristics of the ALMS loop. Our frequency domain analyses prove that the ALMS loop has an effect of amplifying the frequency components of the residual SI at the edges of the signal spectrum in the analog domain. However, the matched filter in the receiver chain will reduce this effect, resulting …

Performance Simulation And Evaluation Of Net Zero Energy Buildings In An Australian Coastal Climate, Joel Anderson, Duane A. Robinson, Zhenjun Ma

Faculty of Engineering and Information Sciences - Papers: Part B

Net zero energy buildings (NZEB) are becoming more common, and as new energy saving designs and technologies become available, the ability to estimate overall energy use and understand the impact on operation of building appliances will become important. This paper outlines simulation results of performance improvements achieved by modifying various components (glazing, lighting, thermal comfort settings) of two tertiary education NZEBs and a typical modern commercial building. The DesignBuilder models' thermal performance and energy consumption were validated using real data from case study buildings. The work shows validating models of smaller, less conven-tional, buildings is more difficult than for larger …

Dual Effects Of Tisio4composite Nanoparticles On Dispersionstability And Lubrication Performance Of Vegetable Oil‐In‐Water Emulsions, Reza Taheri, Buyung Kosasih, Hongtao Zhu, Anh Kiet Tieu

Faculty of Engineering and Information Sciences - Papers: Part B

Vegetable oil-in-water emulsions are potential metal-working lubricants. These emulsions are susceptible to oil-water phase separation due to the oil droplets' coalescence. In this study, we enhance the dispersion stability and lubricity of such emulsions with TiSiO4 nanoparticles (NPs). With 1 vol% soybean oil, stable emulsions are obtained with 0.25 to 0.75 wt% NPs, attributed to formation of shielding layers of NPs around the droplets. Lowest friction and wear are obtained without and with 0.25 wt% NPs, respectively. With increasing the NPs' mass fraction, NP-shielded droplets become less attracted to metal surfaces. Association of NPs within boundary film is also found …

Probing Fretting Performance Of Dlc And Mos2 Films Under Fluid Lubrication, Wenhua Zhuang, Hao Li, Wen Li, Xiaoqiang Fan, Jifan He, Zhenbing Cai, Wang Fu, Guangan Zhang, Shanhong Wan, Minhao Zhu

Faculty of Engineering and Information Sciences - Papers: Part B

Transition from onefold to synergistic lubrication for solving fretting wear and fatigue problems is of great practical significance, because fluids can regulate fretting regime for minimizing wear, solid films can restrain nucleation and formation of crack. Here synergistic lubrication coatings were prepared using diamond-like carbon (DLC) and molybdenum disulfide (MoS2) films as anti-wear/fatigue layer, and high-performance lubricants (including silicone oil, ionic liquids, multialkylated cyclopentanes and perfluoropolyethers (PFPE)) as flowable lubrication layer. Their fretting performance was evaluated in detail and fretting mechanism was revealed by surface/interface analysis techniques. Results determine the synergistic lubrication coatings with good anti-wear and anti-fatigue abilities, deriving …

Study On Performance Evaluation Of Co2 Heat Pump System Integrated With Thermal Energy Storage For Space Heating, Zhihua Wang, Yuxin Zheng, Fenghao Wang, Mengjie Song, Zhenjun Ma

Faculty of Engineering and Information Sciences - Papers: Part B

CO2 heat pumps have drawn a great deal of attention owing to their advantages of high efficiency and environmental friendly for heating water under low ambient temperature. However, the system performance is not desirable and shows a lower COP for space heating, especially for a radiator as heating terminal, due to the higher inlet water temperature at the gas cooler, which causes a large throttle loss when the refrigerant flow through the throttling device. To tackle this issue, a transcritical CO2 heat pump system integrated with thermal energy storage (TES) systems was developed in this paper. The heating performance of …

Influence Of Soil Clogging On The Performance Of Jute Fibre Drains Installed In Ballina Clay, Thanh Trung Nguyen, Buddhima Indraratna, John Philip Carter

Faculty of Engineering and Information Sciences - Papers: Part B

Biodegradable prefabricated vertical drains (BPVD) made from naturally occurring materials such as jute and coconut (coir) fibre not only have favourable engineering characteristics but also not detri-mental to the natural environment thanks to their biodegradability. Although the use of these natural fibre drains has been proposed for several decades, their application is still very limited. One of major reasons for this is because they are usually composed of individual fibres with large openings which can trap fine soils while discharging pore pressure, consequently reducing the hydraulic conductivity of the drain. This study therefore aims to clarify how soil can clog …

Improved Performance Of Ballasted Tracks At Transition Zones: A Review Of Experimental And Modelling Approaches, Buddhima Indraratna, Muhammad Babar Sajjad, Ngoc Trung Ngo, A Correia, Richard B. Kelly

Faculty of Engineering and Information Sciences - Papers: Part B

Track transitionssuch as bridge approaches, road crossings and shifts from slab track to ballasted track are common locations wheretrack degradation accelerates due to dynamic and high impact forces; as a consequence there is higher differential settlement. Thesetypes of discontinuities cause an abrupt change in the structural responseof the track due mainly tovariations in stiffness and track damping. Track transitionzones are prone to an accelerated deterioration of track material and geometrythat leads to increased maintenance costs.Track deteriorationalso leads to vehicle degradation due to enhanced acceleration, low frequency oscillation, and high frequency vibrations. While ballastdeterioration is amajor factor affecting thestability and longevity …

Thermoelectric Performance Of Single-Phase Tellurium-Reduced Quaternary (Pbte)0.55(Pbs)0.1(Pbse)0.35, Laaya Shaabani, Graeme Blake, Andrew Manettas, Shokat Keshavarzi, Sima Aminorroaya-Yamini

Australian Institute for Innovative Materials - Papers

Lead chalcogenide quaternary systems have been shown to provide high thermoelectric (TE) efficiency superior to those of binary andternary lead chalcogenides, arising from both altered electronic band structures and a reduction in lattice thermal conductivity. Here, we have synthesized single-phase samples of the quaternary compound (PbTe)0.55(PbS)0.1(PbSe)0.35 dopedwith Na and characterized their TE properties. We show that the dopant solubility is limited to 1 at. %. A very low lattice thermal conductivity of∼0.6 Wm−1K−1at 850 K is achieved at all dopant concentrations because of phonon scattering from point defects associated with solute atoms with high contrastatomic mass. As a result, a …

Understanding The Structure-Property-Performance Relationship Of Silicon Negative Electrodes, Jiazhi Hu

Theses and Dissertations--Chemical and Materials Engineering

Rechargeable lithium ion batteries (LIBs) have long been used to power not only portable devices, e.g., mobile phones and laptops, but also large scale systems, e.g., electrical grid and electric vehicles. To meet the ever increasing demand for renewable energy storage, tremendous efforts have been devoted to improving the energy/power density of LIBs. Known for its high theoretical capacity (4200 mAh/g), silicon has been considered as one of the most promising negative electrode materials for high-energy-density LIBs. However, diffusion-induced stresses can cause fracture and, consequently, rapid degradation in the electrochemical performance of Si-based negative electrodes. To mitigate the detrimental effects …

Speech Interfaces And Pilot Performance: A Meta-Analysis, Kenneth A. Ward

International Journal of Aviation, Aeronautics, and Aerospace

As the aviation industry modernizes, new technology and interfaces must support growing aircraft complexity without increasing pilot workload. Natural language processing presents just such a simple and intuitive interface, yet the performance implications for use by pilots remain unknown. A meta-analysis was conducted to understand performance effects of using speech and voice interfaces in a series of pilot task analogs. The inclusion criteria selected studies that involved participants performing a demanding primary task, such as driving, while interacting with a vehicle system to enter numbers, dial radios, or enter a navigation destination. Compared to manual system interfaces, voice interfaces reduced …

The Effect Of Communication And Vehicle Properties On The Search Performance Of A Swarm Of Unmanned Aerial Vehicles, Jenna E. Newcomb, Andrew Ning

Faculty Publications

An unmanned aerial vehicle (UAV) swarm allows for a more time-efficient method of searching a specified area than a single UAV or piloted plane. There are a variety of factors that affect how well an area is surveyed. We specifically analyzed the effect both vehicle properties and communication had on the swarm search performance. We used non-dimensionalization to examine the effect vehicle properties had on search performance so the results can be applied to any domain size with any number and type of vehicle. We found that even if vehicles could only sense 10% of the grid area at any …