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Full-Text Articles in Science and Technology Studies

Coupled Discrete Element-Finite Difference Method For Analysing The Load-Deformation Behaviour Of A Single Stone Column In Soft Soil, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn, Scott W. Sloan Jan 2015

Coupled Discrete Element-Finite Difference Method For Analysing The Load-Deformation Behaviour Of A Single Stone Column In Soft Soil, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn, Scott W. Sloan

Faculty of Engineering and Information Sciences - Papers: Part A

Experimental studies and numerical modelling of the deformation of soft clay stabilised by stone columns have been conducted over the past few decades. Continuum-based numerical models have provided valuable insight into the prediction of settlement, lateral deformation, and stress and strain-rate dependent behaviour of stone columns at a macroscopic scale, but because they consist of granular material such as crushed rock, gravel, and waste rock aggregates, their behaviour is influenced by inter-particle micromechanics and cannot be modelled properly using these models. In this paper a novel coupled model of the discrete element method (DEM) and finite difference method (FDM) is ...


Study On Surface Asperity Flattening In Cold Quasi-Static Uniaxial Planar Compression By Crystal Plasticity Finite Element Method, Hejie Li, Zhengyi Jiang, Dongbin Wei, Jianzhong Xu, Xiaoming Zhang, Dianyao Gong, Jingtao Han Jan 2015

Study On Surface Asperity Flattening In Cold Quasi-Static Uniaxial Planar Compression By Crystal Plasticity Finite Element Method, Hejie Li, Zhengyi Jiang, Dongbin Wei, Jianzhong Xu, Xiaoming Zhang, Dianyao Gong, Jingtao Han

Faculty of Engineering and Information Sciences - Papers: Part A

In order to study the surface asperity flattening in a quasi-static cold uniaxial planar compression, the experimental results of atomic force microscope and electron backscattered diffraction have been employed in a ratedependent crystal plasticity model to analyze this process. The simulation results show a good agreement with the experimental results: in this quasi-static deformation process, lubrication can hinder the surface asperity flattening process even under very low deformation rate. However, due to the limitation of the model and some parameters, the simulation results cannot predict all the properties in detail such as S orientation {123}and the maximum stress in ...


A Study Of The Behaviour Of Fresh And Coal Fouled Ballast Reinforced By Geogrid Using The Discrete Element Method, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn Jan 2015

A Study Of The Behaviour Of Fresh And Coal Fouled Ballast Reinforced By Geogrid Using The Discrete Element Method, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn

Faculty of Engineering and Information Sciences - Papers: Part A

Geogrids are widely used in ballasted rail tracks for reinforcement and stabilisation. During train operation, ballast becomes contaminated or fouled due to infiltration of fines from the surface, mud pumping from the subgrade, and degradation, which decreases the performance of the geogrids. This paper presents the results of a laboratory and numerical simulation to study the effect that coal fines have on the interface between ballast and geogrid. The stress-strain behaviour of fresh and fouled ballast reinforced by geogrid was investigated via a series of large scale direct shear tests in the laboratory and numerical simulations using the Discrete Element ...


Phase Unwrapping Method Based On Multiple Fringe Patterns Without Use Of Equivalent Wavelengths, Limei Song, Yulan Chang, Jiangtao Xi, Qinghua Guo, Xin-Jun Zhu, Xiaojie Li Jan 2015

Phase Unwrapping Method Based On Multiple Fringe Patterns Without Use Of Equivalent Wavelengths, Limei Song, Yulan Chang, Jiangtao Xi, Qinghua Guo, Xin-Jun Zhu, Xiaojie Li

Faculty of Engineering and Information Sciences - Papers: Part A

In order to decrease the noise enhancement in the process of phase unwrapping, we present a new phase unwrapping approach for multiple wavelength phase shift profilometry. In this approach, a series of fringe images with only three wavelengths are captured by the 3D measurement system, and it does not need to calculate the equivalent wavelengths and the equivalent phases. As a result, the noise enhancement is avoided, leading to improved precision in the absolute phase map recovery. Experiment results demonstrate that the proposed method is more robust and effective compared to the existing TWPSP method.


A Tensor-Based Subspace Wall Clutter Mitigation Method For Through-The-Wall Radar Imaging, Fok Hing Chi Tivive, Abdesselam Bouzerdoum Jan 2015

A Tensor-Based Subspace Wall Clutter Mitigation Method For Through-The-Wall Radar Imaging, Fok Hing Chi Tivive, Abdesselam Bouzerdoum

Faculty of Engineering and Information Sciences - Papers: Part A

In through-the-wall radar imaging, targets behind the wall reflect weak electromagnetic signals that are obscured by the strong returns from exterior wall, rendering the detection and classification of indoor stationary targets very difficult. In this paper, a tensor-based subspace method is proposed for wall clutter mitigation. The radar signals received from the antenna array are transformed into a data tensor. Higher-order singular value decomposition is used to segregate the wall reflections from the target returns. Simulation and experimental results show that the proposed method is effective in removing reflections backscattered from both homogeneous and heterogeneous walls.


An Application Of Mathematical Morphology Operators As Features Extraction Method For Low Speed Slew Bearing Condition Monitoring, Wahyu Caesarendra, Dwi B. Wibowo, Mochammad Ariyanto, Joga D. Setiawan Jan 2015

An Application Of Mathematical Morphology Operators As Features Extraction Method For Low Speed Slew Bearing Condition Monitoring, Wahyu Caesarendra, Dwi B. Wibowo, Mochammad Ariyanto, Joga D. Setiawan

Faculty of Engineering and Information Sciences - Papers: Part A

This paper presents a new application of mathematical morphology (MM) operators for low speed slew bearing condition monitoring. The MM operators were used as a signal processing step and feature extraction method for bearing vibration signals. Four basic MM operators; erosion, dilation, closing and opening, were studied. This paper also investigates another potential MM operator, namely gradient operator. Two common time domain features in bearing condition monitoring, namely root mean square (RMS) and kurtosis, were extracted from the processed signal. The study shows that the changes in bearing condition can be clearly detected from the extracted features (RMS and kurtosis ...


Improved Method For Estimation Of Multiple Parameters In Self-Mixing Interferometry, Yan Gao, Yanguang Yu, Jiangtao Xi, Qinghua Guo, Jun Tong, Sheng Tong Jan 2015

Improved Method For Estimation Of Multiple Parameters In Self-Mixing Interferometry, Yan Gao, Yanguang Yu, Jiangtao Xi, Qinghua Guo, Jun Tong, Sheng Tong

Faculty of Engineering and Information Sciences - Papers: Part A

There are two categories of applications for self-mixing interference (SMI)-based sensing: (1) estimation of parameters associated with a semiconductor laser (SL) and (2) measurement of the metrological quantities of the external target. To achieve high resolution sensing, each category of applications requires knowledge from the other. This paper proposes an improved method that can simultaneously measure the parameters of an SL and the target movement in arbitrary form. Starting with the existing SMI model, we derive a new matrix equation for the measurement. The measurement matrix is built by employing all the available data samples obtained from an SMI ...


Shadow Removal Method For Phase-Shifting Profilometry, Lei Lu, Jiangtao Xi, Yanguang Yu, Qinghua Guo, Yongkai Yin, Limei Song Jan 2015

Shadow Removal Method For Phase-Shifting Profilometry, Lei Lu, Jiangtao Xi, Yanguang Yu, Qinghua Guo, Yongkai Yin, Limei Song

Faculty of Engineering and Information Sciences - Papers: Part A

In a typical phase-shifting profilometry system for the three-dimensional (3D) shape measurement, shadows often exist in the captured images as the camera and projector probe the object from different directions. The shadow areas do not reflect the fringe patterns which will cause errors in the measurement results. This paper proposed a new method to remove the shadow areas from taking part in the 3D measurement. With the system calibrated and the object reconstructed, the 3D results are mapped on a point-by-point basis into the corresponding positions on the digital micro-mirror device (DMD) of the projector. A set of roles are ...


Sensitivity Of Collapsed Arc Qa Method For Delivery Errors In Volumetric Modulated Arc Therapy (Vmat), Tony Young, Aitang Xing, Philip J. Vial, David Thwaites, Lois C. Holloway, Sankar Arumugam Jan 2015

Sensitivity Of Collapsed Arc Qa Method For Delivery Errors In Volumetric Modulated Arc Therapy (Vmat), Tony Young, Aitang Xing, Philip J. Vial, David Thwaites, Lois C. Holloway, Sankar Arumugam

Faculty of Engineering and Information Sciences - Papers: Part A

In this paper the sensitivity of an Electronic Portal Imaging Device (EPID) to detecting introduced Volumetric Arc Therapy (VMAT) treatment errors was studied using the Collapsed Arc method. Two clinical Head and Neck (H& N) and Prostate treatment plans had gantry dependent dose and MLC errors introduced to the plans. These plans were then delivered to an Elekta Synergy Linear Accelerator EPID and compared to the original treatment planning system Collapsed Arc dose matrix. With the Collapsed Arc technique the EPID was able to detect MLC errors down to 2mm and dose errors of down to 3% depending on the ...


Simple Method For Measuring The Linewidth Enhancement Factor Of Semiconductor Lasers, Yuanlong Fan, Yanguang Yu, Jiangtao Xi, Ginu Rajan, Qinghua Guo, Jun Tong Jan 2015

Simple Method For Measuring The Linewidth Enhancement Factor Of Semiconductor Lasers, Yuanlong Fan, Yanguang Yu, Jiangtao Xi, Ginu Rajan, Qinghua Guo, Jun Tong

Faculty of Engineering and Information Sciences - Papers: Part A

A simple method for measuring the linewidth enhancement factor (LEF) of semiconductor lasers (SLs) is proposed and demonstrated in this paper. This method is based on the self-mixing effect when a small portion of optical signal intensity emitted by the SL reflected by the moving target re-enters the SL cavity, leading to a modulation in the SL's output power intensity, in which the modulated envelope shape depends on the optical feedback strength as well as the LEF. By investigating the relationship between the light phase and power from the well-known Lang and Kobayashi equations, it was found that the ...


A Practical Tuning Method For The Robust Pid Controller With Velocity Feed-Back, Emre Sariyildiz, Haoyong Yu, Kouhei Ohnishi Jan 2015

A Practical Tuning Method For The Robust Pid Controller With Velocity Feed-Back, Emre Sariyildiz, Haoyong Yu, Kouhei Ohnishi

Faculty of Engineering and Information Sciences - Papers: Part B

Proportional-Integral-Derivative (PID) control is the most widely used control method in industrial and academic applications due to its simplicity and efficiency. Several different control methods/algorithms have been proposed to tune the gains of PID controllers. However, the conventional tuning methods do not have sufficient performance and simplicity for practical applications, such as robotics and motion control. The performance of motion control systems may significantly deteriorate by the nonlinear plant uncertainties and unknown external disturbances, such as inertia variations, friction, external loads, etc., i.e., there may be a significant discrepancy between the simulation and experiment if the robustness is ...