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Articles 132181 - 132210 of 187665

Full-Text Articles in Engineering

A Variable Stiffness Mr Damper For Vibration Suppression, Xianzhou Zhang, Weihua Li, Yang Zhou Jan 2009

A Variable Stiffness Mr Damper For Vibration Suppression, Xianzhou Zhang, Weihua Li, Yang Zhou

Faculty of Engineering - Papers (Archive)

This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness damper and analysis its applications in vibration suppression. The MR fluid isolator used a MR valve control unit and bladders to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The effective stiffness and damping coefficients of the isolator under various magnetic fields were identified and the dynamic performances of isolator were evaluated with simulation. …

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Thz Generation By Optical Rectification Involving High-Index Planes, Krunal Radhanpura, Stuart Hargreaves, Roger A. Lewis Jan 2009

Thz Generation By Optical Rectification Involving High-Index Planes, Krunal Radhanpura, Stuart Hargreaves, Roger A. Lewis

Faculty of Engineering - Papers (Archive)

We report a theoretical and experimental study of the generation of THz radiation by optical rectification from high-index planes of GaAs crystals.

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Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic Jan 2009

Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic

Faculty of Engineering - Papers (Archive)

We have systematically studied the flux pinning behavior of MgB2 bulks synthesized by direct diffusion of Mg into pressed pellets of high purity crystalline B powder, with and without mixing with C and SiC nanoparticles, at a reaction temperature of 850degC for 10 hrs. All of the samples showed very high purity and high density, but their microstructure and flux pinning behavior showed significant differences. It was found that the pure MgB2 agrees with the deltaTc pinning model, nano-C doped MgB2 agrees with the deltal pinning model, while the SiC+MgB2 composite agrees …

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Microstructure And Mechanical Properties Of Thermomechanically Processed Trip Steel, Ilana B. Timokhina, Peter D. Hodgson, Hossein Beladi, E V. Pereloma Jan 2009

Microstructure And Mechanical Properties Of Thermomechanically Processed Trip Steel, Ilana B. Timokhina, Peter D. Hodgson, Hossein Beladi, E V. Pereloma

Faculty of Engineering - Papers (Archive)

The strengthening mechanism responsible for the unique combination of ultimate tensile strength and elongation in a multiphase Fe-0.2C-1.5Mn-1.2Si-0.3Mo-0.6Al-0.02Nb (wt%) steel was studied. The microstructures with different volume fractions of polygonal ferrite, bainite and retained austenite were simulated by controlled thermomechanical processing. The interrupted tensile test was used to study the bainitic ferrite, retained austenite and polygonal ferrite behaviour as a function of plastic strain. X-ray analysis was used to characterise the volume fraction and carbon content of retained austenite. Transmission electron microscopy was utilised to analyse the effect of bainitic ferrite morphology on the strain induced transformation of retained austenite …

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Quantitative Description Of Critical Current Density In Ybco Films And Multilayers, Alexey V. Pan, Serhiy Pysarenko, S X. Dou Jan 2009

Quantitative Description Of Critical Current Density In Ybco Films And Multilayers, Alexey V. Pan, Serhiy Pysarenko, S X. Dou

Faculty of Engineering - Papers (Archive)

The vortex pinning model based on the presence of the large number of edge dislocations in high quality YBa2Cu3O7 (YBCO) films and multilayers has been refined. By introducing the pinning potential of a chain of individual edge dislocations, we have been able not only to describe the critical current density dependence on the applied magnetic field over its entire range, but also to extract the microstructural parameters in the films, such as inter-dislocation spacing and average domain size, without employing sophisticated microstructural analysis. The model applicability and its results have been verified with the help …

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Spin Wave Scattering And Interface Magnetism In Superconducting-Ferromagnet-Superconducting Hybrid Structures, Gustavo A. Alvarez, Xiaolin Wang, T Puzzer, Germanas Peleckis, S. X. Dou Jan 2009

Spin Wave Scattering And Interface Magnetism In Superconducting-Ferromagnet-Superconducting Hybrid Structures, Gustavo A. Alvarez, Xiaolin Wang, T Puzzer, Germanas Peleckis, S. X. Dou

Faculty of Engineering - Papers (Archive)

In this work we report on interlayer spin-polarized transport studies carried out on YBa2Cu3O7-δ/La2/3Sr1/3MnO3/YBa2Cu3O7-δ thin film multilayers. Anisotropic YBa2Cu3O7-δ high-temperature superconductors (YBCO) and the manganite La2/3Sr1/3MnO3 (LSMO) are layered metallic systems where the c-axis interlayer current transport occurs via sequential tunneling of charge carriers. The temperature dependence of the resistance R(T) for different applied fields shows that these heterostructures are clearly influenced by both the insulator-to-metal …

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Hydrothermal Synthesis And Optical, Magnetic And Supercapacitance Properties Of Nanoporous Cobalt Oxide Nanorodes, Guoxiu Wang, Xiaoping Shen, Josip Horvat, Bei Wang, Hao Liu, David Wexler, Jane Yao Jan 2009

Hydrothermal Synthesis And Optical, Magnetic And Supercapacitance Properties Of Nanoporous Cobalt Oxide Nanorodes, Guoxiu Wang, Xiaoping Shen, Josip Horvat, Bei Wang, Hao Liu, David Wexler, Jane Yao

Faculty of Engineering - Papers (Archive)

Nanoporous cobalt oxide nanorods were synthesized by a hydrothermal method. Transmission electron microscopy analysis showed that the individual Co3O4 nanorods have a nanoporous structure, consisting of the textured aggregations of nanocrystals. Optical properties of Co3O4 nanorods were characterized by Raman and UV−vis spectroscopy. Magnetic property measurement shows that Co3O4 nanorods have a low Néel transition temperature of 35 K. We observed quite significant exchange bias for nanoporous Co3O4 nanorods, indicating the existence of magnetic coupling between the nanocrystals in Co3O4 nanorods. When applied as electrode …

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Simulation Of Impulsive Loading On Column Using Inflatable Airbag Technique, Alexander Remennikov, J Y Richard Liew, Kong Sih Ying, K W. Kang Jan 2009

Simulation Of Impulsive Loading On Column Using Inflatable Airbag Technique, Alexander Remennikov, J Y Richard Liew, Kong Sih Ying, K W. Kang

Faculty of Engineering - Papers (Archive)

The purpose of this study was to simulate impulsive loading on columns by an innovative lab-based experimental technique that utilises inflatable airbags. Mild and stainless steel hollow sectioin columns with effective lengths of 955mm and under simply supported condition were used in this study.

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An Age-Based Inspection And Replacement Policy For Heterogeneous Components, Philip A. Scarf, Cristiano A. V. Cavalcante, Richard A. Dwight, Peter Gordon Jan 2009

An Age-Based Inspection And Replacement Policy For Heterogeneous Components, Philip A. Scarf, Cristiano A. V. Cavalcante, Richard A. Dwight, Peter Gordon

Faculty of Engineering - Papers (Archive)

This paper considers a hybrid maintenance policy for a single component from a heterogeneous population. The component is placed in a socket, and the component and socket together comprise the system. The s-population of components consists of two sub-populations with different failure characteristics. By supposing that a component may be in a defective but operating state, so that there exists a delay time between defect arrival and component failure, we consider a novel maintenance policy that is a hybrid of inspection and replacement policies. There are similarities in this approach with the concept of ldquoburn-inrdquo maintenance. The policies are …

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Superconductivity Of Various Borides: The Role Of Stretched C-Parameter, Monika Mudgel, V P. Awana, H Kishan, I Felner, Gustavo A. Alvarez, G L. Bhalla Jan 2009

Superconductivity Of Various Borides: The Role Of Stretched C-Parameter, Monika Mudgel, V P. Awana, H Kishan, I Felner, Gustavo A. Alvarez, G L. Bhalla

Faculty of Engineering - Papers (Archive)

The superconductivity of MgB2, AlB2, NbB2+x, and TaB2+x is intercompared. The stretched c-lattice parameter (c = 3.52 Å) of MgB2 in comparison to NbB2.4 (c = 3.32 Å) and AlB2 (c = 3.25 Å) decides empirically the population of their π and σ bands and as a result their transition temperature Tc values, respectively, at 39 and 9.5 K for the first two and no superconductivity for the later. The nonstoichiometry induces an increase in c parameter with Boron excess both in NbB …

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Magnetic Glassy Behaviour In Ferroelectric Relaxor Type Solid Solutions: Magnetelectric Relaxor, Zhenxiang Cheng, Xiaolin Wang, Gustavo A. Alvarez, S. X. Dou, Shujun Zhang, Thomas R. Shrout Jan 2009

Magnetic Glassy Behaviour In Ferroelectric Relaxor Type Solid Solutions: Magnetelectric Relaxor, Zhenxiang Cheng, Xiaolin Wang, Gustavo A. Alvarez, S. X. Dou, Shujun Zhang, Thomas R. Shrout

Faculty of Engineering - Papers (Archive)

Perovskite solid solution ceramics with compositions of 0.9Pb(Fe0.5Nb0.5)O3–0.1PbTiO3, 0.6Pb(Ni1/3Nb2/3)O3–0.4PbTiO3, and 0.6Pb(Co1/3Nb2/3)O3–0.4PbTiO3 were synthesized by the traditional solid state reaction method. Ferroelectric measurements revealed that these samples have well saturated polarization-electrical field loops. Dielectric measurements showed that abnormal dielectric peaks at their Curie temperature were frequency dependent. Both characteristics indicate that these samples are relaxor type ferroelectric materials. Field cooled and zero field cooled magnetization measurements revealed that the 0.6Pb(Ni1/3Nb2/3)O3–0.4PbTiO3 and …

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Behaviour Of Eccentric Loading Of Frp Confined Fibre Steel Reinforced Concrete Columns, Muhammad N. S Hadi Jan 2009

Behaviour Of Eccentric Loading Of Frp Confined Fibre Steel Reinforced Concrete Columns, Muhammad N. S Hadi

Faculty of Engineering - Papers (Archive)

This paper presents results of testing 16 specimens, 12 of which as columns under different eccentricitiesand four as beams under four point loading regime. All 16 specimens were circular in cross section andwere made of reinforced concrete. Four specimens served as reference specimens and were just made ofreinforced concrete. The next four specimens were wrapped with carbon fibre reinforced polymers(CFRP). The next four specimens had steel fibres added to the concrete. The final four specimens werereinforced with steel fibres and wrapped with CFRP. From each group of specimens, one specimen wastested as a column under a concentric load, the second …

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Project Based Learning In The First Year Engineering Curriculum, Brad Stappenbelt, Chris Rowles Jan 2009

Project Based Learning In The First Year Engineering Curriculum, Brad Stappenbelt, Chris Rowles

Faculty of Engineering - Papers (Archive)

This paper examines the implementation of a project-based learning approach in the first year engineering curriculum at the University of Western Australia (UWA). As part of this initiative, the Engineers Without Borders (EWB) Challenge was employed as the focus of student activity within the core undergraduate unit Introduction to Professional Engineering. This unit is the foundation of the professional development component of the engineering degree at UWA. The EWB Challenge provided students with the opportunity to learn about professional engineering whilst contributing towards a real international development project. To create a successful project based learning environment, a comprehensive tutor training …

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Optimization Of Nominal Mixing Ratio Of Mg To B In Fabrication Of Magnesium Diboride Bulk, Yun Zhang, Cheng Lu, Sihai Zhou, Kookchae Chung, Wenxian Li Jan 2009

Optimization Of Nominal Mixing Ratio Of Mg To B In Fabrication Of Magnesium Diboride Bulk, Yun Zhang, Cheng Lu, Sihai Zhou, Kookchae Chung, Wenxian Li

Faculty of Engineering - Papers (Archive)

In this paper bulk magnesium diboride (MgxB2) with x varying from 0.9 to 1.3 was prepared by solid state reaction. The Mg:B mixing ratio for ideal MgB2 is 1:2. The samples were sintered at 800degC for 60 h. Quantitative X-ray diffraction (XRD) analysis was performed to obtain the lattice parameters, the microstrain, and the weight fraction of impurities using the Rietveld refinement method. It has been found that the fraction of pure MgB2 phase increases from x = 0.9 to x = 1.1, and then decreases with further increases in x. Mg1.1B …

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Increased Superconductivity For Cnt Doped Mgb2 Sintered In 5t Pulsed Magnetic Field, Wenxian Li, Ying Li, Rong Hua Chen, Rong Zeng, Lin Lu, Yun Zhang, Michael Tomsic, Matthew Rindfleisch, S. X. Dou Jan 2009

Increased Superconductivity For Cnt Doped Mgb2 Sintered In 5t Pulsed Magnetic Field, Wenxian Li, Ying Li, Rong Hua Chen, Rong Zeng, Lin Lu, Yun Zhang, Michael Tomsic, Matthew Rindfleisch, S. X. Dou

Faculty of Engineering - Papers (Archive)

The superconductivity of carbon nanotube (CNT) doped MgB2 sintered in pulsed magnetic field (PMF) was investigated with Raman scattering measurements and Raman spectral fit analysis. Although the carbon (C) substitution for the boron (B) is increased for the sample sintered in PMF, its superconductivity is advanced comparing with the sample sintered without PMF. The improved critical transition temperature, Tc, is attributed to the strengthening of the electron-phonon coupling (EPC) in MgB2, as reflected by the broadened E 2g mode in the Raman spectra, because the carbon atoms are homogeneously distributed in the boron planes.

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Carbon Nanotube Network Modified Carbon Fibre Paper For Li Ion Batteries, Jun Chen, Jiazhao Wang, Andrew I. Minett, Yong Liu, Carol M. Lynam, Hua-Kun Liu, G G. Wallace Jan 2009

Carbon Nanotube Network Modified Carbon Fibre Paper For Li Ion Batteries, Jun Chen, Jiazhao Wang, Andrew I. Minett, Yong Liu, Carol M. Lynam, Hua-Kun Liu, G G. Wallace

Faculty of Engineering - Papers (Archive)

Here we report on the direct deposition of large quantities of highly porous carbon nanotube networks onto a carbon fibre paper support; subsequently utilised as the anode in a Li-ion battery application showing improved long-term performance and chemical stability with a significant fully reversible capacity of 546mAh/g.

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Development Of A Force Sensor Working With Mr Elastomers, Weihua Li, Kosta Kostidis, Xianzhou Zhang, Yang Zhou Jan 2009

Development Of A Force Sensor Working With Mr Elastomers, Weihua Li, Kosta Kostidis, Xianzhou Zhang, Yang Zhou

Faculty of Engineering - Papers (Archive)

This paper presents the development of a new force sensor with MR elastomer as a sensing element. One key element in this study was to find a suitable material with high sensing capabilities which can be used for developing a sensor. Thus different MR elastomers, with ingredients of carbonyl iron particle, graphite, silicone oil and silicone rubber, were manufactured and measured with a modified rheometer. The effects of additives on the sensing capabilities were systematically investigated and an optimal MR elastomer sample was selected for design and manufacturing of a force sensor prototype. The development sensor prototype consists of three …

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Mechanism For Initiating Secondary Currents In Channel Flows, Shuqing Yang Jan 2009

Mechanism For Initiating Secondary Currents In Channel Flows, Shuqing Yang

Faculty of Engineering - Papers (Archive)

This study investigates the underlying mechanisms that initiate secondary flow in developing turbulent flow along a corner. This is done by theoretical examination of the total shear stress, which is the time-averaged product of instantaneous streamwise velocity U and the velocity Vn normal to the interface. The study shows that lines of zero total shear stress exist in the flow region, which delineate the region of secondary flow. Therefore, the flow region is dividable and eight vortices occur in a duct flow. The theoretical and experimental results show that the division line, separating the neighboring secondary currents in a corner, …

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Influence Of Heat Treatment On Superconductivity Of Mgb2 Bulk Sintered In Flowing Welding Grade Ar Atmosphere, Yun Zhang, Cheng Lu, Sihai Zhou, K. C. Chung, Y. K. Kim, S. X. Dou Jan 2009

Influence Of Heat Treatment On Superconductivity Of Mgb2 Bulk Sintered In Flowing Welding Grade Ar Atmosphere, Yun Zhang, Cheng Lu, Sihai Zhou, K. C. Chung, Y. K. Kim, S. X. Dou

Faculty of Engineering - Papers (Archive)

In this paper, MgB2 samples were sintered in flowing welding grade Ar. The effect of the sintering time varying from 10 minutes to 3 hours on superconductivity of MgB2 has been investigated. It has been found that both Hc2 and Hirr increase with the sintering time and they have linear relationships with microstrain. The sample sintered for 30 min exhibits the highest Jc at high fields. The reason can be attributed to the improved connectivity and the increased Hc2.

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Behavior Of Cemented Soft Clays In Undrained Situations, Suksun Horpibulsuk, Jirayut Suebsuk, Martin D. Liu Jan 2009

Behavior Of Cemented Soft Clays In Undrained Situations, Suksun Horpibulsuk, Jirayut Suebsuk, Martin D. Liu

Faculty of Engineering - Papers (Archive)

In this paper, a constitutive model for cemented clay is introduced. This model is designated as "Modified Structured Cam Clay (MSCC) model". In the model, the influence of cementation structure is incorporated into effective stress concept, yield function, hardening rule and plastic potential function to describe the mechanical behavior of cemented clay during strain-hardening and softening. The methodology of modeling the shear behavior of structured clay is simple, which is the same way as that of the other models of the Cam Clay family. The capability of the MSCC model is verified by comparing the simulated undrained shear response of …

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A Bio-Inspired Robotic Locomotion System Based On Conducting Polymer Actuators, Gursel Alici, Daniel Gunderson Jan 2009

A Bio-Inspired Robotic Locomotion System Based On Conducting Polymer Actuators, Gursel Alici, Daniel Gunderson

Faculty of Engineering - Papers (Archive)

This paper presents the conceptual design and testing of a bio-inspired locomotion system activated through ionic-type conducting polymer actuators, which can operate both in dry and wet environments. The locomotion system is proposed for a mini autonomous crawling device for applications typified by pipe inspection, search, inspection and data gathering in confined spaces, which require mini-robotic systems. The locomotion system is based on the cilia, which has a simple planar bending motion. This type of motion can be provided by bending-type polymer actuators (one-end fixed and the other-end free cantilever beam). The actuators mounted on a printed circuit board and …

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Variable Stiffness And Damping Mr Isolator, Xianzhou Zhang, Weihua Li, Xingyu Wang, Kosta Kostidis Jan 2009

Variable Stiffness And Damping Mr Isolator, Xianzhou Zhang, Weihua Li, Xingyu Wang, Kosta Kostidis

Faculty of Engineering - Papers (Archive)

This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness and damping isolator for vibration suppressions. The MR fluid isolator used a sole MR control unit to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, and a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The parameters of the model under various magnetic fields were identified and the dynamic performances of isolator were evaluated.

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Applications Of Hydraulic Properties Models On Microscopic Flow In Unsaturated Porous Media, Thidarat Bunsri, Muttucumaru Sivakumar, Dharmappa Hagare Jan 2009

Applications Of Hydraulic Properties Models On Microscopic Flow In Unsaturated Porous Media, Thidarat Bunsri, Muttucumaru Sivakumar, Dharmappa Hagare

Faculty of Engineering - Papers (Archive)

Several existing equations for solving the non-linear soil-hydraulic properties are introduced and validated to field and laboratory measured data. Models for non-linear hydraulic properties of unsaturated porous media arise from statistical and mathematical fit through the measured data and they can be expressed in forms of unsaturated permeability versus either pressure head or volumetric moisture content. This paper presents the difference models: Gardner, Knuze et al., Haverkamp et al., van Genuchten and Saxton et al. for calculation of hydraulic properties coefficients, typicallyunsaturated permeability. The accurate and computational efficiency of these five existing models are evaluated for a series of study …

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Synthesis And Magnetorheological Effect Of Fe3o4-Tio2 Nanocomposite, Jianhong Wei, C J Leng, Xianzhou Zhang, Weihua Li, Z Y Liu, J Shi Jan 2009

Synthesis And Magnetorheological Effect Of Fe3o4-Tio2 Nanocomposite, Jianhong Wei, C J Leng, Xianzhou Zhang, Weihua Li, Z Y Liu, J Shi

Faculty of Engineering - Papers (Archive)

Aimed to obtain a material with improved rheological property, the Fe3O4-TiO2 nanocomposites were prepared by a modified sol-gel processing. The structure and morphology of the Fe3O4-TiO2 nanocomposites were examined by transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and Fourier transform infrared spectroscopy (FT-IR) analysis, etc. The magnetic property and the magnetorheological properties of the coated particles were also examined in detail. The experimental results demonstrated that such materials exhibited favorable magnetorheological (MR) effect, and the MR performance of them were dependent on the relative content of TiO2 in …

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Mre Properties Under Shear And Squeeze Modes And Applications, Kristin Popp, Matthias Kroger, Weihua Li, Xianzhou Zhang, Prabuono B. Kosasih Jan 2009

Mre Properties Under Shear And Squeeze Modes And Applications, Kristin Popp, Matthias Kroger, Weihua Li, Xianzhou Zhang, Prabuono B. Kosasih

Faculty of Engineering - Papers (Archive)

Magnetorheological elastomers (MREs) are smart materials whose mechanical properties, like their modulus and elasticity, can be controlled by an external magnetic field. This feature has resulted in a number of novel applications, such as adaptive tuned dynamic vibration absorbers for suppressing unwanted vibrations over a wide frequency range. MRE-based devices operate in different modes, such as shear mode and squeeze mode; however, the study of mechanical performances of MREs under squeeze mode is very rare. This article aims to investigate MRE performances under both shear and squeeze modes. Experimental studies and simulations were conducted to analyze the MR effect in …

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Comparison Of Photoexcited P-Inas Thz Radiation Source With Conventional Thermal Radiation Sources, Michael Smith, Rajind Mendis, Rodney E. Vickers, Roger A. Lewis Jan 2009

Comparison Of Photoexcited P-Inas Thz Radiation Source With Conventional Thermal Radiation Sources, Michael Smith, Rajind Mendis, Rodney E. Vickers, Roger A. Lewis

Faculty of Engineering - Papers (Archive)

P-type InAs excited by ultrashort optical pulses has been shown to be a strong emitter of terahertz radiation. In a direct comparison between a p-InAs emitter and conventional thermal radiation sources, we demonstrate that under typical excitation conditions p-InAs produces more radiation below 1.2 THz than a globar. By treating the globar as a blackbody emitter we calibrate a silicon bolometer which is used to determine the power of the p-InAs emitter. The emitted terahertz power was found to be 98±10 nW in this experiment.

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Coexistence Of Ferromagnetism And Cluster Glass State In Superconducting Ferromagnet Rusr2eu1.5ce0.5cu2o10, Rashmi Nigam, Alexey V. Pan, S X. Dou Jan 2009

Coexistence Of Ferromagnetism And Cluster Glass State In Superconducting Ferromagnet Rusr2eu1.5ce0.5cu2o10, Rashmi Nigam, Alexey V. Pan, S X. Dou

Faculty of Engineering - Papers (Archive)

Systematic dc and ac magnetic susceptibility measurements performed on RuSr2Eu1.5Ce0.5Cu2O10−δ (Ru1222) demonstrate a paramagnetic to ferromagnetic transition around 95 K. The third harmonic of the ac susceptibility reveals that the system undergoes a spin glass transition below 75 K. The features of the zero-field cooled and field cooled dc magnetization curves of Ru1222 material resemble those of a cluster glass state, rather than those of a canonical spin glass state. The magnetization versus applied field loops do not saturate, even at very high applied fields, resulting in the short range …

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Magnetic Phase Transitions In Pr1-Xluxmn2ge2 Compounds, S X. Dou, Jianli Wang, Maxim Avdeev, A J Studer, Rong Zeng, Stewart J. Campbell Jan 2009

Magnetic Phase Transitions In Pr1-Xluxmn2ge2 Compounds, S X. Dou, Jianli Wang, Maxim Avdeev, A J Studer, Rong Zeng, Stewart J. Campbell

Faculty of Engineering - Papers (Archive)

The effects of replacing Pr by Lu on the magnetic behaviour and structures of Pr1−xLuxMn2Ge2 (x = 0.2,x = 0.4) have been investigated using x-ray diffraction, Mössbauer spectroscopy, magnetization and neutron diffraction measurements. The substitution of Lu for Pr leads to a decrease in the lattice constants a, c and the unit cell volume V at room temperature with this contraction of the unit cell resulting in modifications of the Pr1−xLuxMn2Ge2 magnetic structures. Four and five magnetic phase transitions—linked primarily with …

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Generalization Of Acid Properties, Brahim Medjahed, Mourad Ouzzani, Ahmed Elmagarmid Jan 2009

Generalization Of Acid Properties, Brahim Medjahed, Mourad Ouzzani, Ahmed Elmagarmid

Cyber Center Publications

ACID (Atomicity, Consistency, Isolation, and Durability) is a set of properties that guarantee the reliability of database transactions [2]. ACID properties were initially developed with traditional, business-oriented applications (e.g., banking) in mind. Hence, they do not fully support the functional and performance requirements of advanced database applications such as computer-aided design, computer-aided manufacturing, office automation, network management, multidatabases, and mobile databases. For instance, transactions in computer-aided design applications are generally of long duration and preserving the traditional ACID properties in such transactions would require locking resources for long periods of time. This has lead to the generalization of ACID properties …

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Beyond K-Anonymity: A Decision Theoretic Framework For Assessing Privacy Risk, Guy Lebanon, Monica Scannapieco, Mohamed Fouad, Elisa Bertino Jan 2009

Beyond K-Anonymity: A Decision Theoretic Framework For Assessing Privacy Risk, Guy Lebanon, Monica Scannapieco, Mohamed Fouad, Elisa Bertino

Cyber Center Publications

An important issue any organization or individual has to face when managing data containing sensitive information, is the risk that can be incurred when releasing such data. Even though data may be sanitized before being released, it is still possible for an adversary to reconstruct the original data using additional information thus resulting in privacy violations. To date, however, a systematic approach to quantify such risks is not available. In this paper we develop a framework, based on statistical decision theory, that assesses the relationship between the disclosed data and the resulting privacy risk. We model the problem of deciding …

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