Find Research Output

Research Output
  • All
  • Scholar Profiles
  • Research Units
  • Research Output
Department Publication Year Content Type Data Sources

81.Micro-Cracks Identification and Characterization on the Sheds of Composite Insulators by Fractal Dimension

Author:Jin, H;Lv, ZK;Yuan, ZK;Wei, ZX;Wang, C;Wang, C;Tu, YP;Li, F;Chen, T;Xiao, P


Abstract:The phenomenon of micro-cracks on the sheds is due to aging of the composite insulator. With the development of the Unmanned Aerial Vehicle (UAV) technology, the online aging characterization based on micro-cracks turns out to be a reality. In this article, the micro-cracks identification and characterization on the sheds of composite insulators based on visible spectrum image was studied. At first, the shed area was segmented after graying and binarization operation. Then, the Laplace of Gaussian (LoG) operator and Otsu algorithm were used to extract the texture of micro-cracks. Box-counting method was used to calculate the fractal dimension of the micro-cracks on the composite insulator shed. The index of fractal dimension, a number between 1 and 2, can be used to describe the roughness and density of fractal dimension. The higher the fractal dimension was, the more severe the micro-cracks would be. The experimental results proved that the method proposed was feasible and effective on micro-cracks identification and characterization.

82.Effects of Biased Irradiation on Charge Trapping in HfO2 Dielectric Thin Films

Author:Mu, YF;Zhao, CZ;Lu, QF;Zhao, C;Qi, YF;Lam, S;Mitrovic, IZ;Taylor, S;Chalker, PR


Abstract:This paper reports the low-dose-rate radiation response of Al-HfO2/SiO2-Si MOS devices, in which the gate dielectric was formed by atomic layer deposition (ALD) with 5-nm equivalent oxide thickness. The degradation of the devices was characterized by a pulse capacitance-voltage (CV) and on-site radiation response technique under continuous gamma (gamma) ray exposure at a relatively low dose rate of 0.116 rad (HfO2)/s. Compared with conventional CV measurements, the proposed measurements extract significant variations of flat-band voltage shift of the hafnium based MOS devices. The large flat-band voltage shift is mainly attributed to the radiation-induced oxide trapped charges, which are not readily compensated by bias-induced charges produced over the measurement timescales (for timescales less than 5 ms). A negative flat-band voltage shift up to -1.02 V was observed under a positive biased irradiation with the total dose up to 40 krad (HfO2) and with the electric field of 0.5 MV/cm. This is attributed to net positive charge generation in the HfO2 oxide layer. The generated charges are transported towards the HfO2/SiO2 interface, and then form effective trapped holes in the HfO2. Similarly, a positive flat-band voltage shift up to 1.1 V was observed from irradiation under negative bias with an electric field of -0.5 MV/cm. The positive shift is mainly due to the accumulation of trapped electrons. Analyses of the experimental results suggest that both hole and electron trapping can dominate the radiation response performance of the HfO2-based MOS devices depending upon the applied bias. It was also found there was no distinct border traps with irradiation in all cases.

83.Some notes on the incompleteness theorem and shape grammars

Author:Theodoros, Dounas

Source:Communications in Computer and Information Science,2013,Vol.369 CCIS

Abstract:The paper presents a critique of the Shape Grammar paradigm viewed through the lens of the incompleteness theorem of Go¨del. Shape Grammars have been extensively researched through many lenses. Their productive systemic nature was the focus of the first papers along with more recent treatises in the field while their use in analysis of known building styles has been extensive and a proven mechanism for style analysis. It is surprising though that use of Shape Grammars in actual design in practice however has been minimal. The architectural community has not actively used the paradigm in the design of real buildings, probably because of the rigid analytical approach to style and rules, following from the academic analysis that the paradigm has been subjected to. However I propose that there is another underlying reason, other than the rigid approach to construct a Shape Grammar. The nature of the concurrent application and creation of the rules lies close to the incompleteness theorem of Go¨del, that uses a multitude of Turing Machines to prove that a from a set of True Axioms-A-we will never be able to determine if all sentences are true, without having to invent new axioms, outside the initial set-A-, thus unproven in terms of their true or false nature. Negation of this possibility drives us to the conclusion that true Design can never be feature-complete and thus can never be placed in a trusted framework that we all agree or believe it to be the complete truth. © 2013 Springer-Verlag Berlin Heidelberg.

84.From geometrically to algebraically described hyperbolic paraboloids: An optimisation-based analysis of the Philips Pavilion


Source:RE: Anthropocene, Design in the Age of Humans - Proceedings of the 25th International Conference on Computer-Aided Architectural Design Research in Asia, CAADRIA 2020,2020,Vol.1

Abstract:In this paper, we present a procedure to derive algebraic parameters from geometrically described truncated hyperbolic paraboloid surfaces. The procedure uses parametric modelling and optimisation to converge on close algebraic approximations of hyperbolic paraboloid geometry through a successive breakdown of vast search spaces. We illustrate this procedure with its application to the surfaces of the 1958 Philips Pavilion designed by Le Corbusier and Iannis Xenakis. This application yielded previously unavailable parametric data of this building in algebraic form. It highlights the power of the parametric design and optimisation toolkit, both in terms of automated search and epistemological enablement.

85.Forecast of Freight Volume in Xi'an Based on Gray GM (1,1) Model and Markov Forecasting Model

Author:Yang, F;Tang, XY;Gan, YX;Zhang, XD;Li, JC;Han, X


Abstract:Due to the continuous improvement of productivity, the transportation demand of freight volume is also increasing. It is difficult to organize freight transportation efficiently when the freight volume is quite large. Therefore, predicting the total amount of goods transported is essential in order to ensure efficient and orderly transportation. Aiming at optimizing the forecast of freight volume, this paper predicts the freight volume in Xi'an based on the Gray GM (1, 1) model and Markov forecasting model. Firstly, the Gray GM (1, 1) model is established based on related freight volume data of Xi'an from 2000 to 2008. Then, the corresponding time sequence and expression of restore value of Xi'an freight volume can be attained by determining parameters, so as to obtain the gray forecast values of Xi'an's freight volume from 2009 to 2013. In combination with the Markov chain process, the random sequence state is divided into three categories. By determining the state transition probability matrix, the probability value of the sequence in each state and the predicted median value corresponding to each state can be obtained. Finally, the revised predicted values of the freight volume based on the Gray-Markov forecasting model in Xi'an from 2009 to 2013 are calculated. It is proved in theory and practice that the Gray-Markov forecasting model has high accuracy and can provide relevant policy bases for the traffic management department of Xi'an.

86.Polygonal rotopulsators of the curved n-body problem

Author:Tibboel, P


Abstract:We revisit polygonal positive elliptic rotopulsator solutions and polygonal negative elliptic rotopulsator solutions of the n-body problem in H-3 and S-3 and prove the existence of these solutions and prove that the masses of these rotopulsators have to be equal if the rotopulsators are of nonconstant size and show that the number of negative elliptic relative equilibria of this type is finite, as is the number of positive elliptic relative equilibria if an upper bound on the size of the relative equilibrium is imposed. Additionally, we prove that a class of negative hyperbolic rotopulsators is in fact a subclass of the class of polygonal negative elliptic rotopulsators. Published by AIP Publishing.

87.Editorial for the special issue on modern aspects of financial engineering

Author:Goncu, A


89.Chinese EFL academics' perceptions of research quality: a phenomenological study

Author:Xie, JM;Postlethwaite, K


Abstract:This paper explores how Chinese academics, working in the field of English as Foreign Language Education in universities in China, conceptualise research quality. The paper uses a phenomenological approach and four qualitative methods (survey, interview, focus groups and document analysis) to investigate what a sample of these scholars perceive as high-quality research. We found that the participants viewed quality through various lenses and identified several different criteria. We categorised their elaboration of the criteria under three headings: methodology, contextualisation and impact. The participants nominated many general criteria that were similar to western standards of research quality, especially in relation to methodology; however, some contextual criteria were specific to the Chinese context. The paper indicates that there is much in the university research community that could be altered to enable people who are directly involved in research to disseminate their criteria for research quality, and potentially to affect and develop the quality of educational research in the Chinese context, and/or elsewhere.

90.Minimum and Maximum Principle Sufficiency for a Nonsmooth Variational Inequality

Author:Wu, ZL;Lu, Y


Abstract:In this paper, the minimum and maximum principle sufficiency properties for a nonsmooth variational inequality problem (NVIP) are studied. We discuss the relationship among the solution set of an NVIP and those defined by its dual problem and relevant gap functions. For a pseudomonotone NVIP, the weaker sharpness of its solution set has been shown to be sufficient for it to have minimum principle sufficiency property. As special cases, pseudomonotonicity(*) and pseudomonotonicity(+) of the relevant bifunction have been characterized, from which the minimum and maximum principle sufficiency properties have also been characterized.

91.Artificial Bee Colony Algorithm with Time-Varying Strategy

Author:Qin, QD;Cheng, S;Zhang, QY;Li, L;Shi, YH


Abstract:Artificial bee colony (ABC) is one of the newest additions to the class of swarm intelligence. ABC algorithm has been shown to be competitive with some other population-based algorithms. However, there is still an insufficiency that ABC is good at exploration but poor at exploitation. To make a proper balance between these two conflictive factors, this paper proposed a novel ABC variant with a time-varying strategy where the ratio between the number of employed bees and the number of onlooker bees varies with time. The linear and nonlinear time-varying strategies can be incorporated into the basic ABC algorithm, yielding ABC-LTVS and ABC-NTVS algorithms, respectively. The effects of the added parameters in the two new ABC algorithms are also studied through solving some representative benchmark functions. The proposed ABC algorithm is a simple and easy modification to the structure of the basic ABC algorithm. Moreover, the proposed approach is general and can be incorporated in other ABC variants. A set of 21 benchmark functions in 30 and 50 dimensions are utilized in the experimental studies. The experimental results show the effectiveness of the proposed time-varying strategy.

92.Strong quantum confinement effect and reduced Frohlich exciton-phonon coupling in ZnO quantum dots embedded inside a SiO2 matrix

Author:Ning, JQ;Zheng, CC;Zhang, XH;Xu, SJ


Abstract:ZnO quantum dots (QDs) embedded in an amorphous SiO2 matrix were examined in depth by using variable-temperature photoluminescence (PL) and optical reflectance spectroscopies. Compared with ZnO bulk crystals, ZnO quantum dots with an average size of 4 nm exhibit a strong quantum confinement effect, evidenced by a large blue shift in both PL and reflectance peaks of excitons. More interestingly, a remarkably reduced long-range Frohlich interaction was revealed in ZnO QDs. These fascinating effects may make ZnO QDs a very appealing system in the fields of optoelectronics and others.

93.Privacy perception and protection on Chinese social media: a case study of WeChat

Author:Chen, ZT;Cheung, M


Abstract:In this study, the under-examined area of privacy perception and protection on Chinese social media is investigated. The prevalence of digital technology shapes the social, political and cultural aspects of the lives of urban young adults. The influential Chinese social media platform WeChat is taken as a case study, and the ease of connection, communication and transaction combined with issues of commercialisation and surveillance are discussed in the framework of the privacy paradox. Protective behaviour and tactics are examined through different perceptions of privacy in the digital age. The findings of this study suggest that users possess certain amount of freedoms on WeChat. However, users' individual privacy attitudes and behaviour in practice suggest they have a declined sense of their own freedom and right to privacy. A privacy paradox exists when users, while holding a high level of concerns, in reality do little to further the protection of their personal information on WeChat. We argue that once a user has ingrained part of their social engagement within the WeChat system, the incentive for them to remain a part of the system outweighs their requirement to secure their privacy online as their decision-making is largely based on a simple cost-benefit analysis. The power and social capital yielded via WeChat is too valuable to give up as WeChat is widely used not only for private conversations, but also for study or work-related purposes. It further blurs the boundaries between the public, the professional and the private, which is a rather unique case compared with other social media around the world.

94.A Centralized Reactive Power Compensation System for LV Distribution Networks

Author:Chen, SX;Eddy, YSF;Gooi, HB;Wang, MQ;Lu, SF


Abstract:A centralized reactive power compensation system is proposed for low voltage (LV) distribution networks. It can be connected with any bus which needs reactive power. The current industry practice is to locally install reactive power compensation system to maintain the local bus voltage and power factor. By centralizing capacitor banks together, it can help to maintain bus voltages and power factors as well as reduce the power cable losses. Besides, the centralized reactive power system can be easily expanded to meet any future load increase. A reasonably sized centralized reactive power compensation system will be capable of meeting the requirements of the network and the optimization algorithm proposed in this paper can help to find this optimal size by minimizing the expected total cost (ETCH). Different load situations and their respective probabilities are also considered in the proposed algorithm. The concept of the centralized reactive power compensation system is applied to a local shipyard power system to verify its effectiveness. The results show that an optimally sized centralized reactive power system exists and is capable of maintaining bus voltages as well as reducing the power losses in the distribution network. A significant power loss reduction can be obtained at the optimal capacity of the centralized reactive power compensation system in the case study.

95.Production of "biobetter" variants of glucarpidase with enhanced enzyme activity

Author:Al-Qahtani, AD;Bashraheel, SS;Rashidi, FB;O'Connor, CD;Romero, AR;Domling, A;Goda, SK


Abstract:Glucarpidase, also known as carboxypeptidase G(2), is a Food and Drug Administration-approved enzyme used in targeted cancer strategies such as antibody-directed enzyme prodrug therapy (ADEPT). It is also used in drug detoxification when cancer patients have excessive levels of the anti-cancer agent methotrexate. The application of glucarpidase is limited by its potential immunogenicity and limited catalytic efficiency. To overcome these pitfalls, mutagenesis was applied to the glucarpidase gene of Pseudomonas sp. strain RS-16 to isolate three novels "biobetter" variants with higher specific enzyme activity. DNA sequence analysis of the genes for the variants showed that each had a single point mutation, resulting in the amino acid substitutions: I100 T, G123S and T239 A. K-m, V-max and K-cat measurements confirmed that each variant had increased catalytic efficiency relative to wild type glucarpidase. Additionally, circular dichroism studies indicated that they had a higher alpha-helical content relative to the wild type enzyme. However, three different software packages predicted that they had reduced protein stability, which is consistent with having higher activities as a tradeoff. The novel glucarpidase variants presented in this work could pave the way for more efficient drug detoxification and might allow dose escalation during chemotherapy. They also have the potential to increase the efficiency of ADEPT and to reduce the number of treatment cycles, thereby reducing the risk that patients will develop antibodies to glucarpidase.

96.Urban regeneration in the context of 'New Urbanisation': the case of Xietang Old Street, Suzhou Industrial Park, China

Author:Zhong, S


Abstract:Taking an unassuming case in Suzhou, China, this research examines approaches, strategies and outcomes of recent 'exemplary' regeneration practice in China. It answers the question whether the neo-liberal approaches of the old model have been transcended to honour human-centrality and sustainability in line with 'New Urbanisation principles. Based on surveys, in-depth interviews, a focus group and archival studies, the research finds that the incorporation of social policies into regeneration strategies by the local state, despite achievements in housing and welfare provision, has not helped to transform the top-down and non-participative nature of the old regeneration model.

97.Parametric investigation of polymethacrylate monolith synthesis and stability via thermogravimetric characterisation

Author:Acquah, C;Danquah, MK;Moy, CKS;Anwar, M;Ongkudon, CM


Abstract:Polymethacrylate monoliths are synthetic adsorbents with macroporous and mesoporous interconnected channels that can be engineered to target the hydrodynamic features of a wide range of molecular species. However, rigorous study into the effect of synthesis conditions on their thermal stability is limited. This work attempts to characterise the influence of key synthesis process variables on the stability of polymethacrylate monoliths using thermogravimetric analysis at a heating rate of 10 degrees C/min. Experimental results showed that the thermal stability of polymethacrylate monoliths increased with decreasing polymerisation temperature from 85 to 65 degrees C. Increasing the total porogen (P) to monomer (M) ratio increased the thermal stability of the monolith by >62%% and >50%% for P40/M60-P60/M40 and P60/M40-P80/M20, respectively. The impact of the initiator concentration, monomer variation, biporogen ratio, washing and activation of the monoliths was investigated. Nuclear magnetic resonance analyses conducted confirmed the hydrolysis of epoxy moieties on the monolith. (C) 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

98.Some remarks on a paper of Chetwynd and Hilton on critical star multigraphs

Author:Cariolaro, David

Source:Journal of Combinatorial Mathematics and Combinatorial Computing,2011,Vol.77

Abstract:In [A.G. Chetwynd and A.J.W. Hilton, Critical star multigraphs, Graphs and Combinatorics 2 (1986), 209-221] Chetwynd and Hilton started the investigations of the edge-chromatic properties of a particular class of multigraphs, which they called star multigraphs. A star multigraph is a multigraph such that there exists a vertex v* that is incident with each multiple edge. Star multigraphs turn out to be useful tools in the study of the chromatic index of simple graphs. The main goal of this paper is to provide shorter and simpler proofs of all the main theorems contained in the above mentioned paper. Most simplifications are achieved by means of a formula for the chromatic index recently obtained by the author and by a careful use of arguments involving fans.

99.Homogeneity-preserving property of harmonic sequences from surfaces into complex Grassmann manifolds

Author:Fei Jie;Zhang Wenjuan

Source:Frontiers of Mathematics in China,2017,Vol.12

Abstract:We prove that if phi is a homogeneous harmonic map from a Riemann surface M into a complex Grassmann manifold G(k,n), then the maps of the harmonic sequences generated by phi are all homogeneous.

100.Numerical Study to Examine the Effect of Porosity on In-Flight Particle Dynamics

Author:Kamnis, S;Gu, S;Vardavoulias, M


Abstract:High velocity oxygen fuel (HVOF) thermal spray has been widely used to deposit hard composite materials such as WC-Co powders for wear-resistant applications. Powder morphology varies according to production methods while new powder manufacturing techniques produce porous powders containing air voids which are not interconnected. The porous microstructure within the powder will influence in-flight thermal and aerodynamic behavior of particles which is expected to be different from fully solid powder. This article is devoted to study the heat and momentum transfer in a HVOF sprayed WC-Co particles with different sizes and porosity levels. The results highlight the importance of thermal gradients inside the particles as a result of microporosity and how HVOF operating parameters need to be modified considering such temperature gradient.
Total 5,486 results found
Copyright 2006-2020 © Xi'an Jiaotong-Liverpool University 苏ICP备07016150号-1 京公网安备 11010102002019号