摘要：
Black phosphorous (BP), the most thermodynamically stable allotrope of phosphorus, is a high-mobility layered semiconductor with direct band-gap determined by the number of layers from 0.3 eV (bulk) to 2.0 eV (single layer). Therefore, BP is considered as a natural candidate for broadband optical applications, particularly in the infrared (IR) and mid-IR part of the spectrum. The strong light-matter interaction, narrow direct band-gap, and wide range of tunable optical response make BP as a promising nonlinear optical material, particularly with great potentials for infrared and mid-infrared opto-electronics. Herein, we experimentally verified its broadband and enhanced saturable absorption of multi-layer BP (with a thickness of similar to 10 nm) by wide-band Z-scan measurement technique, and anticipated that multi-layer BPs could be developed as another new type of two-dimensional saturable absorber with operation bandwidth ranging from the visible (400 nm) towards mid-IR (at least 1930 nm). Our results might suggest that ultra-thin multi-layer BP films could be potentially developed as broadband ultra-fast photonics devices, such as passive Q-switcher, mode-locker, optical switcher etc. (C) 2015 Optical Society of America
作者机构：
[Yang, Shengxiang] School of Computer Science and Informatics, De Montfort University, Leicester LE1 9BH, United Kingdom;[Zheng, Jinhua] College of Information Engineering, Xiangtan University, Xiangtan 411105, China;[Liu, Xiaohui; Li, Miqing] Department of Information Systems and Computing, Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom
摘要：
Balancing convergence and diversity plays a key role in evolutionary multiobjective optimization (EMO). Most current EMO algorithms perform well on problems with two or three objectives, but encounter difficulties in their scalability to many-objective optimization. This paper proposes a grid-based evolutionary algorithm (GrEA) to solve many-objective optimization problems. Our aim is to exploit the potential of the grid-based approach to strengthen the selection pressure toward the optimal direction while maintaining an extensive and uniform distribution among solutions. To this end, two concepts-grid dominance and grid difference-are introduced to determine the mutual relationship of individuals in a grid environment. Three grid-based criteria, i.e., grid ranking, grid crowding distance, and grid coordinate point distance, are incorporated into the fitness of individuals to distinguish them in both the mating and environmental selection processes. Moreover, a fitness adjustment strategy is developed by adaptively punishing individuals based on the neighborhood and grid dominance relations in order to avoid partial overcrowding as well as guide the search toward different directions in the archive. Six state-of-the-art EMO algorithms are selected as the peer algorithms to validate GrEA. A series of extensive experiments is conducted on 52 instances of nine test problems taken from three test suites. The experimental results show the effectiveness and competitiveness of the proposed GrEA in balancing convergence and diversity. The solution set obtained by GrEA can achieve a better coverage of the Pareto front than that obtained by other algorithms on most of the tested problems. Additionally, a parametric study reveals interesting insights of the division parameter in a grid and also indicates useful values for problems with different characteristics.
期刊：
SIGNAL PROCESSING,2011年91(4):949-954 ISSN：0165-1684
通讯作者：
Li, CQ
作者机构：
[Lo, Kwok-Tung; Li, Chengqing] Department of Electronic and Information Engineering, Hong Kong Polytechnic University, Hong Kong, Hong Kong;[Li, Chengqing] College of Information Engineering, Xiangtan University, Xiangtan 411105, Hunan, China
摘要：
Recently, an image scrambling encryption algorithm of pixel bit based on chaos map was proposed. Considering the algorithm as a typical binary image scrambling/permutation algorithm exerting on plaintext of size M x (8N), this paper proposes a novel optimal method to break it with some known/chosen-plaintexts. The spatial complexity and computational complexity of the attack are only O(32 . MN) and O(16 . n(0) . MN) respectively, where no is the number of known/chosen-plaintexts used. The method can be easily extended to break any permutation-only encryption scheme exerting on plaintext of size M x N and with L different levels of values. The corresponding spatial complexity and computational complexity are only O(MN) and O(inverted right perpendicularlog(L)(MN)inverted left perpendicular . MN) respectively. In addition, some specific remarks on the performance of the image scrambling encryption algorithm are presented. (C) 2010 Elsevier B.V. All rights reserved.
期刊：
Energy and Environmental Science,2014年7(2):655-661 ISSN：1754-5692
通讯作者：
Zhang, Q.(eqzhang@ntu.edu.sg)
作者机构：
[ Wang, Xinghui ; Susantyoko, Rahmat Agung ; Xiao, Qizhen ; Zhang, Qing ; Fan, Yu ] NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore;[Xiao, Qizhen ] Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105, China
关键词：
Assembling techniques - Electron transport - High specific capacity - Lithium-ion battery - Mechanical support - Multilayer structures - Scalable methods - Storage capacity
作者机构：
[Li, Chengqing ; Xie, Tao ; Liu, Yuansheng ] MOE Key Laboratory of Intelligent Computing and Information Processing, College of Information Engineering, Xiangtan University, Xiangtan 411105 Hunan, China;[ Chen, Michael Z. Q. ] Department of Mechanical Engineering, University of Hong Kong, Hong Kong, Hong Kong
摘要：
Recently, a novel image encryption scheme based on improved hyperchaotic sequences was proposed. A pseudo-random number sequence, generated by a hyper-chaos system, is used to determine two involved encryption functions, bitwise exclusive or (XOR) operation and modulo addition. It was reported that the scheme can be broken with some pairs of chosen plain-images and the corresponding cipher-images. This paper re-evaluates the security of the encryption scheme and finds that the encryption scheme can be broken with only one known plain-image. The performance of the known-plaintext attack, in terms of success probability and computation load, become even much better when two known plain-images are available. In addition, security defects on insensitivity of the encryption result with respect to changes of secret key and plain-image are also reported.
期刊：
IET CONTROL THEORY AND APPLICATIONS,2012年6(2):229-234 ISSN：1751-8644
通讯作者：
Lan, YH
作者机构：
[Zhou, Y.] School of Mathematics and Computational Science, Xiangtan University, Xiangtan, Hunan 411105, China;[Huang, H. -X.; Lan, Y. -H.] School of Information Engineering, Xiangtan University, Xiangtan, Hunan 411105, China
作者：
Wang, Qianxue;Yu, Simin;Li, Chengqing;Lu, Jinhu;Fang, Xiaole;Guyeux, Christophe;Bahi, Jacques M.
期刊：
IEEE Transactions on Circuits and Systems I: Regular Papers,2016年63(3):401-412 ISSN：1549-8328
通讯作者：
Yu, SM;Li, CQ;Lu, JH
作者机构：
[Bahi, Jacques M.; Guyeux, Christophe] Femto-st Institute, UMR 6174, University of Franche-Comté[Bahi, Jacques M.; Guyeux, Christophe] , Besancon, France;[Yu, Simin; Wang, Qianxue] College of Automation, Guangdong University of Technology, Guangzhou, China;[Fang, Xiaole] Land and Resources Technology Center of Guangdong Province, Guangzhou, China;[Li, Chengqing] College of Information Engineering, Xiangtan University, Xiangtan, China
通讯机构：
[Lu, JH] Chinese Acad Sci, Acad Math & Syst Sci, Beijing 100190, Peoples R China.;[Li, CQ] Xiangtan Univ, Coll Informat Engn, Xiangtan 411105, Peoples R China.;[Yu, SM] Guangdong Univ Technol, Coll Automat, Guangzhou 510006, Guangdong, Peoples R China.
关键词：
Chaotic encryption;dynamical degradation;FPGA implementation;high-dimensional digital chaotic system;random number generator
作者：
Fan, Yu;Zhang, Qing;Xiao, Qizhen;Wang, Xinghui;Huang, Kai
期刊：
Carbon,2013年59(00):264-269 ISSN：0008-6223
通讯作者：
Zhang, Q
作者机构：
[Huang, Kai] Key Laboratory of Quantum Engineering and Micro-Nano Energy Technology, Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan 411105, China;[Zhang, Qing; Xiao, Qizhen; Wang, Xinghui; Fan, Yu] Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore, Singapore
摘要：
We report a carbon nanotube (CNT)-silicon core-shell nanowire for lithium ion battery anodes. In this material, the core consists of vertically aligned CNTs synthesized through plasma enhanced chemical vapor deposition. The CNTs exhibit quite large diameters and large inter-wire spacing and are advantageous in strain accommodation and electrolyte access. The silicon shell is tailored with a thickness gradient along its length to eliminate excessive strain accumulation at the nanowire roots and cater for free space distribution in the CNT core array. In addition, the silicon shell exhibits a unique vertically opened pore structure, which is expected to have further improved strain accommodation and Li+ transport. As a result, the CNT-silicon anode demonstrates excellent cyclability with a capacity retention of more than 90% over 100 cycles. It also shows remarkable rate performance that is to our knowledge, the best among all core-shell nanowires reported. (C) 2013 Elsevier Ltd. All rights reserved.
摘要：
The paper deals with the forced oscillation of the fractional differential equation (D(a)(a)x)(t)f(1)(t,x(t)=v(t)f(2)(t,x(t)) for t>a >= 0 with the initial conditions (D(a)(a-k)x)(a)=b(k)(k=1,2,...,m-1) and lim(t -> a+)(l(a)(m-a)x)(t)=b(m), where D(a)(a)x is the Riemann-Liouville fractional derivative of order q of x, m-1<q <= m, m >= 1 is an integer, l(a)(m-a)x is the Riemann-Liouville fractional integral of order m-q of x, and b(k) (k=1,2,...,m) are/is constants/constant. We obtain some oscillation theorems for the equation by reducing the fractional differential equation to the equivalent Volterra fractional integral equation and by applying Young's inequality. We also establish some new oscillation criteria for the equation when the Riemann-Liouville fractional operator is replaced by the Caputo fractional operator. The results obtained here improve and extend some existing results. An example is given to illustrate our theoretical results.
摘要：
A study was conducted to demonstrate zinc oxide (ZnO) meso-mechano-thermo physical chemistry. ZnO exhibited strong piezoelectric and dilute magnetic properties dominating at sites of defects or varying with surface crystal morphology. ZnO provided an impact on applications in forthcoming technologies, such as biomedical sensors,6 actuators, solar cells, catalysis, energy harvesting, and photonic crystals. Experimental observations showed that the Young's modulus of ZnO nanostructures increased when the operating temperature dropped and the thermal effect was modeled based on the third law of thermodynamics. The modeling approaches implemented complemented the advanced models to provide consistent and deeper insight into the size, shape, temperature, and pressure effects on the known bulk ZnO properties and the emerging properties associated with the ndercoordinated atoms at the surfaces and defects of ZnO.
期刊：
SIGNAL PROCESSING,2016年118:203-210 ISSN：0165-1684
通讯作者：
Li, CQ
作者机构：
[Li, Chengqing] MOE (Ministry of Education), Key Laboratory of Intelligent Computing and Information Processing, College of Information Engineering, Xiangtan University, Xiangtan, Hunan, China
摘要：
In year 2000, an efficient hierarchical chaotic image encryption (HCIE) algorithm was proposed, which divides a plain-image of size M x N with T possible value levels into K blocks of the same size and then operates position permutation on two levels: intra-block and inter-block. As a typical position permutation-only encryption algorithm, it has received intensive attention. The present paper analyzes specific security performance of HCIE against ciphertext-only attack and known/chosen-plaintext attack. It is found that only O(inverted right perpendicularlog(T)(M center dot N/K)inverted left perpendicular) known/chosen plain-images are sufficient to achieve a good performance, and the computational complexity is O(M center dot N center dot inverted right perpendicularlog(T)(M center dot N/K)inverted left perpendicular), which effectively demonstrates that hierarchical permutation-only image encryption algorithms are less secure than normal (i.e., non-hierarchical) ones. Detailed experiment results are given to verify the feasibility of the known-plaintext attack. In addition, it is pointed out that the security of HCIE against ciphertext-only attack was much overestimated. (C) 2015 Elsevier B.V. All rights reserved.
作者机构：
[ Zhang, Leo Yu ] State Grid Electric Power Research Institute, Qinghe, Beijing 100192, China;[Li, Chengqing ; Ou, Rong ] College of Information Engineering, Xiangtan University, Xiangtan 411105 Hunan, China;[ Shu, Shi ; Zhang, Leo Yu ] School of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105 Hunan, China;[ Wong, Kwok-Wo ] Department of Electronic Engineering, City University of Hong Kong, Hong Kong, Hong Kong
期刊：
Physical Review A - Atomic, Molecular, and Optical Physics,2010年82(2) ISSN：1050-2947
通讯作者：
Li, Q
作者机构：
[Li, Qin; Chan, W. H.] Department of Mathematics, Hong Kong Baptist University, Kowloon, Hong Kong;[Li, Qin; Long, Dong-Yang] Department of Computer Science, Sun Yat-sen University, Guangzhou 510006, China;[Li, Qin] College of Information Engineering, Xiangtan University, Xiangtan 411105, China
摘要：
In this paper, the Crank-Nicolson (CN) difference scheme for the coupled nonlinear Schrodinger equations with the Riesz space fractional derivative is studied. The existence of this difference solution is proved by the Brouwer fixed point theorem. The stability and convergence of the CN scheme are discussed in the L-2 norm. When the fractional order is two, all those results are in accord with the difference scheme developed for the classical non-fractional coupled nonlinear Schrodinger equations. Some numerical examples are also presented. (C) 2013 Elsevier Inc. All rights reserved.
期刊：
INFORMATION SCIENCES,2012年182(1):220-242 ISSN：0020-0255
通讯作者：
Kwong, S
作者机构：
[Zheng, Jinhua; Li, Miqing; Shen, Ruimin] College of Information and Engineering, Xiangtan University, China;[Li, Ke; Kwong, Sam; Cao, Jingjing] Department of Computer Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong
通讯机构：
[Kwong, S] City Univ Hong Kong, Dept Comp Sci, Tat Chee Ave, Kowloon, Hong Kong, Peoples R China.