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Full-Text Articles in Science and Technology Studies
A Bi-Level Decision Model For Customer Churn Analysis, Ya Gao, Guangquan Zhang, Jie Lu, Jun Ma
A Bi-Level Decision Model For Customer Churn Analysis, Ya Gao, Guangquan Zhang, Jie Lu, Jun Ma
Faculty of Engineering and Information Sciences - Papers: Part A
This paper develops a bi-level decision model and a solution approach to optimizing service features for a company to reduce its customer churn rate. First, a bi-level decision model, together with its modeling approach, are developed to describe the gaming relationship between decision makers in a company (service provider) and its customers. Then, a practical solution approach to reaching solutions for the bi-level-modeled customer churn problem is developed. Finally, experiments and case studies are conducted to illustrate the bi-level decision model and the solution approach.
Practical Fabrication And Analysis Of An Optimized Compact Eight-Channel Silicon Arrayed-Waveguide Grating, Hongqiang Li, Yaoting Bai, Xiaye Dong, Enbang Li, Yang Li, Wenqian Zhou, Yu Liu
Practical Fabrication And Analysis Of An Optimized Compact Eight-Channel Silicon Arrayed-Waveguide Grating, Hongqiang Li, Yaoting Bai, Xiaye Dong, Enbang Li, Yang Li, Wenqian Zhou, Yu Liu
Faculty of Engineering and Information Sciences - Papers: Part A
We have designed, fabricated, and characterized a 1 x 8 ultrasmall compact arrayed-waveguide grating (AWG) on silicon-on-insulator (SOI) in a fiber grating demodulation integration microsystem. The miniature AWG, consisting of Si photonic wire waveguides, was designed using the complete modeling simulation in the beam propagation method. The device was fabricated on an SOI substrate and evaluated in the wavelength range around 1.55 μm, with an effective area of 230 x 160 μm. Clear demultiplexing characteristics were observed with a channel spacing of 1.91 nm. The influence of the waveguide widths on crosstalk defined by adjacent channel crosstalk and phase error …
Experimental Demonstration And Analysis Of Compact Silicon-Nanowire-Based Couplers, Hongqiang Li, Xiaye Dong, Yaoting Bai, Enbang Li, Yang Li, Yu Liu, Wenqian Zhou
Experimental Demonstration And Analysis Of Compact Silicon-Nanowire-Based Couplers, Hongqiang Li, Xiaye Dong, Yaoting Bai, Enbang Li, Yang Li, Yu Liu, Wenqian Zhou
Faculty of Engineering and Information Sciences - Papers: Part A
Compact 2 x 2 couplers based on silicon nanowires are fabricated and tested. They include a directional (X) coupler, a cross-gap coupler (CGC), and a multimode interference (MMI) coupler. The length of the X coupler's parallel film waveguide is 1 μm. The theoretical minimum excess loss of the X coupler is 0.73 dB, whereas its experimental value is 1.0817 dB. CGC has a coupling region length of 24 μm. The minimum excess loss of CGC, which is 0.6 dB in theory, is experimentally determined to be 0.6737 dB. Taper waveguides are used as input/output waveguides for the MMI coupler. The …
Analysis Of Axisymmetric Cup Forming Of Metal Foil And Micro Hydroforming Process, Hideki Sato, Kenichi Manabe, Dongbin Wei, Zhengyi Jiang
Analysis Of Axisymmetric Cup Forming Of Metal Foil And Micro Hydroforming Process, Hideki Sato, Kenichi Manabe, Dongbin Wei, Zhengyi Jiang
Faculty of Engineering and Information Sciences - Papers: Part A
A novel forming method "micro hydromechanical deep drawing (MHDD)" is focused to improve the tribological property and forming limit. In this study, a theoretical model for MHDD is developed to investigate the size effect on deformation behavior in micro hydromechanical deep drawing. The effects of fluid pressure, the difference of friction coefficients at inner pockets and outer pockets are considered in the investigation on the size effect of tribological property. The friction force decreases as the scale factor decreases in MHDD process. It is also found that the tribological property in micro scale can be improved by applying the fluid …
Thermal Defect Analysis On Distribution Transformer Using A Rlc Network And Thermography, Geoffrey O. Asiegbu, Ahmed M. A Haidar, Kamarul Hawari
Thermal Defect Analysis On Distribution Transformer Using A Rlc Network And Thermography, Geoffrey O. Asiegbu, Ahmed M. A Haidar, Kamarul Hawari
Faculty of Engineering and Information Sciences - Papers: Part A
Electrical transformers are vital components found virtually in most power-operated equipments. These transformers spontaneously radiate heat in both operation and steady-state mode. Should this thermal radiation inherent in transformers rises above allowable threshold a reduction in efficiency of operation occurs. In addition, this could cause other components in the system to malfunction. The aim of this work is to detect the remote causes of this undesirable thermal rise in transformers such as oil distribution transformers and ways to control this prevailing thermal problem. Oil transformers consist of these components: windings usually made of copper or aluminum conductor, the core normally …
Rectifier Capacitor Filter Stress Analysis When Subject To Regular Voltage Fluctuations, Kun Zhao, Phil Ciufo, Sarath Perera
Rectifier Capacitor Filter Stress Analysis When Subject To Regular Voltage Fluctuations, Kun Zhao, Phil Ciufo, Sarath Perera
Faculty of Engineering and Information Sciences - Papers: Part A
Lamp flicker levels which arise as a result of voltage fluctuations can exceed limits set by appropriate standards. New lamp types such as compact fluorescent lights (CFLs) are less sensitive to voltage fluctuations as their flicker characteristics are considerably different compared to those of the traditional incandescent lamp. These differences could support the moderation of the present voltage fluctuation and flicker standards and hence the associated limits. The potential detrimental effects on electrical equipment which may be caused by relaxation of these limits should be investigated before any changes to the present standards take place. The impact of voltage fluctuations …
Experimental Analysis Of The Magnetic Flux Characteristics Of Saturated Core Fault Current Limiters, Jeffrey W. Moscrop
Experimental Analysis Of The Magnetic Flux Characteristics Of Saturated Core Fault Current Limiters, Jeffrey W. Moscrop
Faculty of Engineering and Information Sciences - Papers: Part A
A fault current limiter (FCL) is a device that is designed to reduce the impact of fault currents on electricity networks and increase the availability of such networks to consumers. One particular FCL technology that is currently attracting worldwide attention, from both researchers and commercial engineering companies, is the saturated core FCL. This device utilizes the change in permeability between the saturated and unsaturated states of a magnetic core to provide both low steady state losses and effective fault current limiting. Typically the core is saturated using an electromagnetic coil, which can be either superconducting or non-superconducting. Although there have …
Trace Elements In The Si Furnace-Part Ii: Analysis Of Condensate In Carbothermal Reduction Of Quartz, Elena Dal Martello, Gabriella Tranell, Oleg Ostrovski, Guangqing Zhang, Ola Raaness, Rune Berg Larsen, Kai Tang, Pramod Koshy
Trace Elements In The Si Furnace-Part Ii: Analysis Of Condensate In Carbothermal Reduction Of Quartz, Elena Dal Martello, Gabriella Tranell, Oleg Ostrovski, Guangqing Zhang, Ola Raaness, Rune Berg Larsen, Kai Tang, Pramod Koshy
Faculty of Engineering and Information Sciences - Papers: Part A
Silicon feedstock for production of solar-grade silicon should be as pure as possible to decrease the cost of manufacturing of solar cells. Impurities in quartz, carbonaceous materials, electrodes, and refractories are mostly present in the form of oxides. These oxides can be reduced to volatile gaseous compounds in presence of SiO(g) and CO(g) atmosphere and potentially leave the furnace or stay in the condensed reaction products, metal, and slag. This work investigates the conditions under which volatile impurities report to the gas phase in laboratory experiments with lumpy and pelletized mixtures of SiO2, SiC, and Si at 1923 K and …
Analysis Of Elemental Segregation In A Microalloyed Cast Steel, Jingwei Zhao, Zhengyi Jiang, Dongbin Wei
Analysis Of Elemental Segregation In A Microalloyed Cast Steel, Jingwei Zhao, Zhengyi Jiang, Dongbin Wei
Faculty of Engineering and Information Sciences - Papers: Part A
Quantitative investigation is made on the elemental segregation in different zones of a heavy microalloyed cast steel by energy dispersive X-ray spectroscopy. It is demonstrated that C shows serious segregation tendency than that of Mn and Si, and the degree of C segregation in the surface zone is higher than that in the central zone. C enrichment is generally observed at both dendrite arm and grain boundaries, and more C segregation at dendrite arm boundary in contrast to that at grain boundary is found in this steel. The distribution of C concentration shows a decreased trend from root to tip …
Encoding Navigable Speech Sources: A Psychoacoustic-Based Analysis-By-Synthesis Approach, Xiguang Zheng, Christian Ritz, Jiangtao Xi
Encoding Navigable Speech Sources: A Psychoacoustic-Based Analysis-By-Synthesis Approach, Xiguang Zheng, Christian Ritz, Jiangtao Xi
Faculty of Engineering and Information Sciences - Papers: Part A
This paper presents a psychoacoustic-based analysis-by-synthesis approach for compressing navigable speech sources. The approach targets multi-party teleconferencing applications, where selective reproduction of individual speech sources is desired. Based on exploiting sparsity of speech in the perceptual time-frequency domain, multiple speech signals are encoded into one mono mixture signal, which can be further compressed using a standard speech codec. Using side information indicating the active speech source for each time frequency instant enables flexible decoding and reproduction. Objective results highlight the importance of considering perception when exploiting the sparse nature of speech in the time-frequency domain. Results show that this sparsity, …
Security Analysis Of A Single Sign-On Mechanism For Distributed Computer Networks, Guilin Wang, Jiangshan Yu, Qi Xie
Security Analysis Of A Single Sign-On Mechanism For Distributed Computer Networks, Guilin Wang, Jiangshan Yu, Qi Xie
Faculty of Engineering and Information Sciences - Papers: Part A
Single sign-on (SSO) is a new authentication mechanism that enables a legal user with a single credential to be authenticated by multiple service providers in a distributed computer network. Recently, Chang and Lee proposed a new SSO scheme and claimed its security by providing well-organized security arguments. In this paper, however, we demonstrative that their scheme is actually insecure as it fails to meet credential privacy and soundness of authentication. Specifically, we present two impersonation attacks. The first attack allows a malicious service provider, who has successfully communicated with a legal user twice, to recover the user's credential and then …
Choosing An Optimal Model For Failure Data Analysis By Graphical Approach, Tieling Zhang, Richard Dwight
Choosing An Optimal Model For Failure Data Analysis By Graphical Approach, Tieling Zhang, Richard Dwight
Faculty of Engineering and Information Sciences - Papers: Part A
Many models involving combination of multiple Weibull distributions, modification of Weibull distribution or extension of its modified ones, etc. have been developed to model a given set of failure data. The application of these models to modeling a given data set can be based on plotting the data on Weibull probability paper (WPP). Of them, two or more models are appropriate to model one typical shape of the fitting plot, whereas a specific model may be fit for analyzing different shapes of the plots. Hence, a problem arises, that is how to choose an optimal model for a given data …
Finite Element Analysis Of Roll Bit Behaviors In Cold Foil Rolling Process, Liang Hao, Zhengyi Jiang, Dongbin Wei, Xiawei Cheng
Finite Element Analysis Of Roll Bit Behaviors In Cold Foil Rolling Process, Liang Hao, Zhengyi Jiang, Dongbin Wei, Xiawei Cheng
Faculty of Engineering and Information Sciences - Papers: Part A
To investigate roll bite behaviors in cold foil rolling process, a 2D elasto-plastic finite model is established using FEM software ABAQUS. Contact pressure distribution and roll contour in roll bite are also presented, which demonstrate that foil rolling process is different from conventional strip rolling process. The contact area is composed of entry elastic zone, entry plastic zone, an extensive neutral zone, exit plastic zone and exit elastic zone. It conforms to the results of Fleck foil rolling theory. Elastic deformation and work hardening of foil in roll bite are taken into account. The effect of rolling parameters, such as …
Microtexture Based Analysis Of Surface Asperity Flattening Behavior Of Annealed Aluminum Alloy In Uniaxial Planar Compression, Hejie Li, Zhengyi Jiang, Dongbin Wei, Xiaoming Zhang
Microtexture Based Analysis Of Surface Asperity Flattening Behavior Of Annealed Aluminum Alloy In Uniaxial Planar Compression, Hejie Li, Zhengyi Jiang, Dongbin Wei, Xiaoming Zhang
Faculty of Engineering and Information Sciences - Papers: Part A
During the uniaxial planar compression of annealed aluminum alloy, a novel approach to determine surface asperity flattening (roughness Ra) is employed by analyzing the evolution of surface microtexture. With an increase in gauged reduction, surface asperity tends to be flattened, and strain hardening increases. Lubrication can constrain the surface asperity flattening process. Development of surface asperity features shows the obvious dependency on [111] orientation. In-grain slips contribute significantly to the evolution of surface microtexture. Influence of deformation twins (brass orientation) on the evolution of microtexture is not obvious under our current experimental conditions.
Security Analysis Of A Distributed Reprogramming Protocol For Wireless Sensor Networks, Yong Yu, Jianbing Ni, Ying Sun
Security Analysis Of A Distributed Reprogramming Protocol For Wireless Sensor Networks, Yong Yu, Jianbing Ni, Ying Sun
Faculty of Engineering and Information Sciences - Papers: Part A
Reprogramming for wireless sensor networks is essential to upload new code or to alter the functionality of existing code. To overcome the weakness of the centralized approach of the traditional solutions, He et al. proposed the notion of distributed reprogramming where multiple authorized network users are able to reprogram sensor nodes without involving the base station. They also gave a novel distributed reprogramming protocol called SDRP by using identity-based signature, and provided a comprehensive security analysis for their protocol. In this letter, unfortunately, we demonstrate that SDRP is insecure as the protocol fails to satisfy the property of authenticity and …
Sludge Formation In The Activated Sludge Process: Mathematical Analysis, Asma O. M Alharbi, Mark I. Nelson, Annette L. Worthy, Harvinder S. Sidhu
Sludge Formation In The Activated Sludge Process: Mathematical Analysis, Asma O. M Alharbi, Mark I. Nelson, Annette L. Worthy, Harvinder S. Sidhu
Faculty of Engineering and Information Sciences - Papers: Part A
One drawback associated with the activated sludge process is the production of 'sludge'. The expense for treating excess sludge can account for 50-60% of the running costs of a plant. Traditional methods for disposing of excess sludge, which include incineration, the use of landfill sites and dumping at sea are becoming increasingly regulated worldwide due to concerns about the presence of potentially toxic elements in it. Furthermore, a combination of the limited amount of land available for landfill, particularly in urban areas, with stringent legislation has seen the economic costs of using landfill sites increasing sharply. Thus there is a …
Rail Track Infrastructure For Enhanced Speed - Analysis Design And Construction Challenges, Buddhima Indraratna, Sanjay Shrawan Nimbalkar, Jayan Sylaja J S Vinod
Rail Track Infrastructure For Enhanced Speed - Analysis Design And Construction Challenges, Buddhima Indraratna, Sanjay Shrawan Nimbalkar, Jayan Sylaja J S Vinod
Faculty of Engineering and Information Sciences - Papers: Part A
Rail is one of the largest transportation modes offering freight and passenger traffic in rapidly developing nations, including India. Conscious efforts to improve productivity, modernization and technology upgrading have led to an impressive growth in railways. Large-scale physical modeling, sophisticated numerical modeling and full-scale field monitoring often provide significant knowledge to better understand track performance and to extend the current state-of-the-art in design. A series of large-scale laboratory tests were conducted to establish relationships between (i) ballast breakage and train speed, (ii) ballast fouling and strength and (iii) interface strength and geogrids. Comprehensive field trials were carried out on instrumented …
Reliability Modeling And Analysis For A Novel Design Of Modular Converter System Of Wind Turbines, Cai Wen Zhang, Tieling Zhang, Nan Chen, Tongdan Jin
Reliability Modeling And Analysis For A Novel Design Of Modular Converter System Of Wind Turbines, Cai Wen Zhang, Tieling Zhang, Nan Chen, Tongdan Jin
Faculty of Engineering and Information Sciences - Papers: Part A
Converters play a vital role in wind turbines. The concept of modularity is gaining in popularity in converter design for modern wind turbines in order to achieve high reliability as well as cost-effectiveness. In this study, we are concerned with a novel topology of modular converter invented by Hjort, Modular converter system with interchangeable converter modules. World Intellectual Property Organization, Pub. No. WO29027520 A2; 5 March 2009, in this architecture, the converter comprises a number of identical and interchangeable basic modules. Each module can operate in either AC/DC or DC/AC mode, depending on whether it functions on the generator or …
Investigation On Slab Continuous Straightening Technology And Deformation Analysis, Xingzhong Zhang, Hongtao Zhu, Wen Huang, Baojun Shi, Anh Kiet Tieu
Investigation On Slab Continuous Straightening Technology And Deformation Analysis, Xingzhong Zhang, Hongtao Zhu, Wen Huang, Baojun Shi, Anh Kiet Tieu
Faculty of Engineering and Information Sciences - Papers: Part A
A new method of setting continuous bending and straightening strain rate according to temperature subzone was brought forward. By making use of the high temperature creep character effectively during the continuous casting slab being straightened, a new model curve of continuous caster was developed. And by using theoretical and finite element method the strain and strain rate of the slab under multi-point straightening and the new continuous straightening were analysed. The result shows that for continuous straightening the strain rate of the slab is constant and lower than that of the slab under multi-point straightening, and the strain varies linearly. …
Analysis Of Interference Factors Of Air Turbine Cascades, Andrei Gareev, Prabuono Buyung Kosasih, Paul Cooper
Analysis Of Interference Factors Of Air Turbine Cascades, Andrei Gareev, Prabuono Buyung Kosasih, Paul Cooper
Faculty of Engineering and Information Sciences - Papers: Part A
This paper reports viscous compressible aerodynamics analysis of two-dimensional cascades (arrays of aerofoils).
Upper Bound Limit Analysis Of Lateral Pile Capacity, Hongyu Qin, Erwin Oh, Wei Dong Guo, P F. Dai
Upper Bound Limit Analysis Of Lateral Pile Capacity, Hongyu Qin, Erwin Oh, Wei Dong Guo, P F. Dai
Faculty of Engineering and Information Sciences - Papers: Part A
The upper bound method of plasticity limit analysis is used to estimate the ultimate capacity of laterally loaded long piles. Based on a generic limiting force (or the ultimate soil resistance per unit length) profile, both freehead and fixed-head piles are considered. The current solutions can be reduced to available solutions for some special cases. Design charts may be constructed to estimate the lateral capacity of piles in terms of plastic moment and the parameters describing the limiting force profile.
Comparative Analysis Of Dynamic Line Rating Models And Feasibility To Minimise Energy Losses In Wind Rich Power Networks, Mathew Simms, Lasantha Meegahapola
Comparative Analysis Of Dynamic Line Rating Models And Feasibility To Minimise Energy Losses In Wind Rich Power Networks, Mathew Simms, Lasantha Meegahapola
Faculty of Engineering and Information Sciences - Papers: Part A
Wind power generation has indicated an exponential increase during last two decades and existing transmission network infrastructure is increasingly becoming inadequate to transmit remotely generated wind power to load centres in the network. The dynamic line rating (DLR) is one of the viable solutions to improve the transmission line ampacity during high wind penetration without investing on an additional transmission network. The main objective of this study is to identify the basic differences between two main line rating standards, since transmission network service providers (TNSPs) heavily depend on these two standards when developing their line rating models. Therefore, a parameter …
Incremental Service Level Agreements Violation Handling With Time Impact Analysis, Azlan Ismail, Jun Yan, Jun Shen
Incremental Service Level Agreements Violation Handling With Time Impact Analysis, Azlan Ismail, Jun Yan, Jun Shen
Faculty of Engineering and Information Sciences - Papers: Part A
This research addresses a critical issue of service level agreement (SLA) violation handling, i.e., time constraint violation related to service-based systems (SBS). Whenever an SLA violation occurs to a service, it can potentially impact dependent services, leading to unreliable SBS. Therefore, an SLA violation handling support is much required to produce a robust and adaptive SBS. There are several approaches to realizing exceptions and faults handling support for SBS, focusing on the detection stage, the analysis stage, and the resolution stage. However, the current works have not considered the handling strategy that takes the impact information into account to reduce …