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ABSTRACT: We introduce a theoretical framework that predicts the optimum planting density and maximal yield for an annual crop plant. Two critical parameters determine the trajectory of plant growth and the optimal density, , where canopies of growing plants just come into contact, and competition: (i) maximal size at maturity, , which differs among varieties due to artificial selection for different usable products; and (ii) intrinsic growth rate, g, which may vary with variety and environmental conditions. The model predicts (i) when planting density is less than , all plants of a crop mature at the same maximal size, , and biomass yield per area increases linearly with density; and (ii) when planting density is greater than , size at maturity and yield decrease with -4/3 and -1/3 powers of density, respectively. Field data from China show that most annual crops, regardless of variety and life form, exhibit similar scaling relations, with maximal size at maturity, , accounting for most of the variation in optimal density, maximal yield, and energy use per area. Crops provide elegantly simple empirical model systems to study basic processes that determine the performance of plants in agricultural and less managed ecosystems.
Proceedings of the National Academy of Sciences 08/2012; 109(39):15823-8. · 9.68 Impact Factor
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Mingsong Wang,
Jiliang Zhu,
Wenliang Zhu,
Bo Zhu, Jing Liu,
Xiaohong Zhu,
Yunti Pu,
Ping Sun,
Zifan Zeng,
Xuhai Li,
Daqing Yuan,
Shengyun Zhu,
Giuseppe Pezzotti
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ABSTRACT: The dielectric constant and electrical conductivity of a composite of two insulators, poly(1,1-difluoroethylene) (yellow) and K(2)CO(3) (white), increased dramatically near the percolation threshold f(c) (f=concentration of K(2)CO(3)). This intriguing phenomenon can be interpreted in terms of interface percolation caused by the formation of chemically activated interfaces.
Angewandte Chemie International Edition 08/2012; 51(36):9123-7. · 13.45 Impact Factor
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IEEE Transactions on Multimedia 01/2012; 14(3-2):883-895. · 1.93 Impact Factor
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SCIENCE CHINA Information Sciences. 01/2012; 55:501-511.
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ABSTRACT: Providing security services for multicast, such as traffic integrity, authentication, and confidentiality, requires securely distributing a group key to group receivers. In the literature, this problem is called multicast key distribution (MKD). A famous MKD protocol-one-way function tree (OFT)-has been found vulnerable to collusion attacks. Solutions to prevent these attacks have been proposed, but at the cost of a higher communication overhead than the original protocol. In this paper, we prove falsity of a recently-proposed necessary and sufficient condition for a collusion attack on the OFT protocol to exist by a counterexample and give a new necessary and sufficient condition for nonexistence of any type of collusion attack on it. We instantiate the general notion of OFT to obtain a particular type of cryptographic construction named homomorphic one-way function tree (HOFT). We propose two structure-preserving graph operations on HOFTs, tree product and tree blinding. One elegant quality possessed by HOFTs is that handling (adding, removing, or changing) leaf nodes in a HOFT can be achieved by using tree product without compromising its structure. We provide algorithms for handling leaf nodes in a HOFT. Employing HOFTs and related algorithms, we put forward a collusion-resistant MKD protocol without losing any communication efficiency compared to the original OFT protocol. We also prove the security of our MKD protocol in a symbolic security model.
IEEE Transactions on Information Forensics and Security 10/2011; · 1.34 Impact Factor
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ABSTRACT: Behavior analysis across multi-cameras becomes more and more popular with the rapid development of camera network in video surveillance. In this paper, we propose a novel unsupervised graph matching framework to associate trajectories across partially overlapping cameras. Firstly, trajectory extraction is based on object extraction and tracking and is followed by a homographic projection to a mosaic-plane. And we extract appearance and spatio-temporal features for trajectory description. Then a robust graph matching algorithm based on reweighted random walk is adopted for trajectory association. The association is formulated as node ranking and selection on an association graph whose nodes represent candidate correspondences of trajectories. Finally, the pairs of corresponding trajectories in overlapping regions are fused by an adaptive averaging scheme, in which trajectories with more observations and longer length is given higher weight. Experiments and comparison on real scenarios demonstrate the effectiveness of the proposed approach.
Image and Graphics (ICIG), 2011 Sixth International Conference on; 09/2011
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ABSTRACT: The modelling and verifying of hybrid systems attract more and more attentions recently. Hybrid automaton is widely used to model discrete and continuous behaviors of hybrid systems. In this paper, a hybrid interface automaton(HIA) is proposed based on hybrid automaton to model the interface behaviors of hybrid components. According to the interface type of components, we define two kinds of HIA to model interface behaviors respectively. The RHIA(Reactive HIA) is used to model the interface behavior of reactive component and AHIA(Active HIA) for active components. In addition, some composition operations for component interface models are given to facilitate component based software development. The main contribution is to describing a composable model of component interfaces with formal methods, which allows static compatibility checking for some kinds of components composition with their interface models. To illustrate the approach, a case study railroad gate control of CBTC is discussed.
Computers, Networks, Systems and Industrial Engineering (CNSI), 2011 First ACIS/JNU International Conference on; 06/2011
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IEEE Transactions on Information Forensics and Security. 01/2011; 6:980-991.
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IACR Cryptology ePrint Archive. 01/2011; 2011:575.
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2011 18th Asia Pacific Software Engineering Conference, Ho Chi Minh, Vietnam, December 5-8, 2011; 01/2011
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Proceedings of the IEEE Congress on Evolutionary Computation, CEC 2011, New Orleans, LA, USA, 5-8 June, 2011; 01/2011
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J. Comput. Sci. Technol. 01/2011; 26:528-537.
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Eighth International Conference on Fuzzy Systems and Knowledge Discovery, FSKD 2011, 26-28 July 2011, Shanghai, China; 01/2011
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Inf. Process. Lett. 01/2011; 111:423-428.
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SCIENCE CHINA Information Sciences. 01/2011; 54:1207-1217.
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Proceedings of the 19th International Conference on Multimedea 2011, Scottsdale, AZ, USA, November 28 - December 1, 2011; 01/2011
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Proceedings of the 10th IEEE International Conference on Cognitive Informatics and Cognitive Computing, ICCI*CC 2011, 18-20 August 2011, Banff, Alberta, Canada; 01/2011
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IEEE Trans. Circuits Syst. Video Techn. 01/2011; 21:853-866.
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J. Comb. Optim. 01/2011; 22:674-683.
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01/2011
