Yun S.,Xian University of Architecture and Technology |
Lim S.,Yonsei University
Journal of Solid State Chemistry | Year: 2011
The application of electrospun nanofibers in electronic devices is limited due to their poor adhesion to conductive substrates. To improve this, a seed layer (SD) is introduced on the FTO substrate before the deposition of the electrospun composite nanofibers. This facilitates the release of interfacial tensile stress during calcination and enhances the interfacial adhesion of the AZO nanofiber films with the FTO substrate. Dye-sensitized solar cells (DSSC) based on these AZO nanofiber photoelectrodes have been fabricated and investigated. An energy conversion efficiency (η) of 0.540.55% has been obtained under irradiation of AM 1.5 simulated sunlight (100 mW/cm2), indicating a massive improvement of η in the AZO nanofiber film DSSCs after SD-treatment of the FTO substrate as compared to those with no treatment. The SD-treatment has been demonstrated to be a simple and facile method to solve the problem of poor adhesion between electrospun nanofibers and the conductive substrate. © 2010 Elsevier Inc. All rights reserved.
Huang G.,Xian University of Architecture and Technology
Swarm and Evolutionary Computation | Year: 2016
To solve some complicated function optimization problems, an artificial infectious disease optimization algorithm based on the SEIQR epidemic model is constructed, it is called as the SEIQR algorithm, or SEIQRA in short. The algorithm supposes that some human individuals exist in an ecosystem; each individual is characterized by a number of features; an infectious disease (SARS) exists in the ecosystem and spreads among individuals, the disease attacks only a part of features of an individual. Each infected individual may pass through such states as susceptibility (S), exposure (E), infection (I), quarantine (Q) and recovery (R). State S, E, I, Q and R can automatically and dynamically divide all people in the ecosystem into five classes, it provides the diversity for SEIQRA; that people can be attacked by the infectious disease and then transfer it to other people can cause information exchange among people, information exchange can make a person to transit from one state to another; state transitions can be transformed into operators of SEIQRA; the algorithm has 13 legal state transitions, which corresponds to 13 operators; the transmission rules of the infectious disease among people is just the logic to control state transitions of individuals among S, E, I, Q and R, it is just the synergy of SEIQRA, the synergy can be transformed into the logic structure of the algorithm. The 13 operators in the algorithm provide a native opportunity to integrate many operations with different purposes; these operations include average, differential, expansion, chevy, reflection and crossover. The 13 operators are executed equi-probably; a stable heart rhythm of the algorithm is realized. Because the infectious disease can only attack a small part of organs of a person when it spreads among people, the part variables iteration strategy (PVI) can be ingeniously applied, thus enabling the algorithm to possess of high performance of computation, high suitability for solving some kinds of complicated optimization problems, especially high dimensional optimization problems. Results show that SEIQRA has characteristics of strong search capability and global convergence, and has a high convergence speed for some complicated functions optimization problems. © 2015 Elsevier B.V. All rights reserved.
Gao D.,Xian University of Architecture and Technology |
Zhang X.,Xian Jiaotong University |
Gao W.,Shaanxi Normal University
ACS Applied Materials and Interfaces | Year: 2013
In this work, the uniform bundle-shaped microtubes composed of six half-pipes are synthesized for the first time in hydrothermal solutions via an intentional delayed phase transition pathway induced by Mn2+ doping. The structural and kinetic factors that govern the phase and shape evolution of NaYF4 microcrystals have been carefully studied, and the influences of Mn2+ to RE3+ ratio, the amount of trisodium citrate, and the pH value in conjunction with the intrinsic character of RE3+ ions on the phase and shape evolution are systematically discussed. It is found that the proper Mn2+ to RE3+ ratio is mainly responsible for delayed phase transition process and induces interior density gradient of solid aggregate for creating hollow bundle-shaped microtubes. While the amount of trisodium citrate and the pH value are the keys for the shape control of the NaYF4 microcrystals such as prismatic microtubes, prismatic short rods, thin plates, and particles. The up and downconversion emissions were obtained independent of whether α- or β-NaYF4:Er 3+/Yb3+ samples doped with Mn2+, but the significant tuning of output color was only obtained in cube NaYF4 nanoparticles rather than in hexagonal microtubes via adjusting the amount of Mn2+ ions. These spectral measurements and EDX analyses indicate that the distribution or concentration of Mn2+ in hexagonal phase solid solution has changed, which supports Ostwald ripening growth mechanism and rules out agglomeration or oriented attachment growth mechanism. We designed crystal growth mode by simply addition of dopant may provide a versatile approach for fabricating a wide range of hollow nano/microcrystals and thus bring us a clearer understanding on the interaction between the dopant reagents and the nano/microcrystals. © 2013 American Chemical Society.
Zhang X.H.,Xian University of Architecture and Technology
European Physical Journal B | Year: 2012
We investigate the coherent electronic transport properties of square-shaped zigzag graphene nanoconstrictions (ZGNC) under transverse strain using recursive Green's function method. We find that the low-bias conductance of ZGNCs is monotonically dependent on the strain in contrast to that of zigzag graphene nanoribbons (ZGNRs), which is unaffected by strain. This result suggests that ZGNCs can be used as elementary building blocks in graphene nanomechanical system devices. In addition, a simplified analytical model is employed to qualitatively explain the strain tuning of the low-bias conductance of ZGNCs. © EDP Sciences, Societá Italiana di Fisica, Springer-Verlag 2012.
Li D.H.W.,City University of Hong Kong |
Yang L.,Xian University of Architecture and Technology |
Lam J.C.,City University of Hong Kong
Energy | Year: 2012
Studies on the impact of climate change on energy use in buildings in the different parts of the world were reviewed. Potential mitigation and adaptation measures were discussed and further research work suggested. In severe cold climates reduction in heating requirement would outweigh the modest increase in summer cooling. In the hot summer and cold winter climate zones where both winter heating and summer cooling requirements are important, the magnitude of reduction in heating and the magnitude of increase in cooling could be comparable. The most significant impact on energy use in the built environment would occur in the hot summer and warm winter climates where building energy use is dominated by cooling requirement. Raising the summer set point temperature and reducing the lighting load density would have great energy savings and hence mitigation potential. Space heating is provided largely by oil- or gas-fired boiler plants whereas space cooling mainly relies on electricity. This would result in a shift towards more electrical demand and could have important implications for the nationwide energy and environmental policy for the built environment. © 2012 Elsevier Ltd.