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1
Content available remote Effects of Sample Size, Sample Accuracy and Environmental Variables on Predictive Performance of MaxEnt Model
Li Y., Ding C.
Polish Journal of Ecology
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2016
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Vol. 64, nr 3
303--312
EN
The availability of sample data, together with detailed environmental factors, has fueled a rapid increase in predictive modeling of species geographic distributions and environmental requirements. We founded that MaxEnt model has provided different descriptions of potential distributions based on different sample size, sample accuracy and environmental background. We used six combinations based on three sample data set and two kinds of environmental variables to estimate the potentially suitable areas of Brown Eared Pheasant (Crossoptilon mantchuricum) in MaxEnt model. The results show that the complex variables provided the higher AUC value and accurate potential distribution than simple variables based on the same size of samples. Complicated environmental factors combined with moderate size and accurate sample, can predict better results. The model results were scabrous based on simple environmental factors. Furthermore, big sample size and simple prediction environmental factors will reduce the prediction accuracy, whereas small samples provided a conservative description of ecological niche. Here, we highlighted that considering the big size and high accuracy of sample and many environmental factors of a species to minimize error when attempting to infer potential distributions from current data in MaxEnt model.
2
Content available Effect of dispersion order on the spectral degree of polarization of stochastic electromagnetic pulsed beams
Wang H., Ding C., Zhang Y., Zhao Z., Pan L.
Optica Applicata
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2014
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Vol. 44, nr 1
147--158
EN
The analytical expression for the cross-spectral density function of stochastic electromagnetic Bessel–Gauss pulsed beams through a dispersive aperture lens is derived and used to study the changes in the spectral degree of polarization in an optical focus system. The changes in the spectral degree of polarization at the focal plane and on the z-axis are performed in the case of dispersion-free, dispersion of the first, second, and higher orders, respectively. It is shown that the dispersion affects the peak value of the spectral degree of polarization, and the higher order dispersion leads to a more obvious effect on the peak value of the spectral degree of polarization at the focal plane. On the z-axis, the spectral degree of polarization in the dispersion-free case is different form that in the dispersion case, however, the dispersion of different orders almost has the same effect on the spectral degree of polarization. The results obtained in this paper may be crucial for high precision laser detection.
3
Content available Delay-dependent dissipative control for stochastic singular systems with state delay
Ding C., Li Q.
Archives of Control Sciences
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2013
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Vol. 23, no. 3
281--293
EN
The problem of delay-dependent dissipative analysis and control for stochastic singular systems with state delay is investigated in this paper. Delay-dependent dissipative condition for the stochastic singular systems with state delay is obtained by employing singular stochastic Lyapunov and LMI-based methods. Based on this condition, a delay-dependent dissipative controller is presented. A numerical example is provided to demonstrate the effectiveness of the proposed approach.
4
Content available remote Effects of Pinus massonian plantations on soil macroarthropods in degraded ultisol, Subtropical China
Ding C., Hu F., Zhou J., Cao Z., Li H., Dai Z.
Archives of Environmental Protection
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2008
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Vol. 34, no. 3
17-20
EN
In the degraded red soil of subtropical China, restoration activities during the last century have mainly relied on extensive plantations of Pinus massonian. We analyze the changes in the soil macroarthropods in P. massonian plantations and the possible relationships between these changes and soil chemical parameters. The study revealed significant differences in the abundance of soil macroarthropods between the P. massonian plantations and the natural regenerated mesophilous herbosa (Nl). The sharply differentiated pattern of soil macroarthropods seems closely linked to soil chemistry. Significant correlations of the abundance of soil macroarthropods with soil parameters suggest that their populations could have been affected by P massonian. The total abundance, the abundance of Hymenoptera and Termite were less in the P. massonian plantations when compared to the natural regenerated mesophilous herbosa (Nl). This survey showed that P.massonian could adversely affect the decomposer community which could lower the nutrient cycling rate, thus P.massonian may not be an ideal plantation for restoration of eroded Ultisol, Subtropical China.
5
Content available remote Secret Sharing Schemes with Nice Access Structures
Ding C., Salomaa A.
Fundamenta Informaticae
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2006
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Vol. 73, nr 1-2
51-63
EN
Secret sharing schemes, introduced by Blakley and Shamir independently in 1979, have a number of applications in security systems. One approach to the construction of secret sharing schemes is based on coding theory. In principle, every linear code can be used to construct secret sharing schemes. But only well structured linear codes give secret sharing schemes with nice access structures in the sense that every pair of participants plays the same role in the secret sharing. In this paper, we construct a class of good linear codes, and use them to obtain a class of secret sharing schemes with nice access structures.
6
Content available remote On Some Problems of Mateescu Concerning Subword Occurrences
Ding C., Salomaa A.
Fundamenta Informaticae
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2006
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Vol. 73, nr 1-2
65-79
EN
The paper investigates inference based on quantities |w|u, the number of occurrences of a word u as a scattered subword of w. Parikh matrices recently introduced are useful tools for such investigations. We introduce and study universal languages for Parikh matrices. We also obtain results concerning the inference from numbers |w|u to w, as well as from certain entries of a Parikh matrix to other entries.
7
Content available remote Construction and enumeration of all binary duadic codes of length p(m)*
Ding C., Lam K.Y., Xing Ch.
Fundamenta Informaticae
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1999
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Vol. 38, Nr 1,2
149-161
EN
In this paper we present a binary-tree approach to the construction of all binary duadic codes of length n = pm. We also calculate the number of binary duadic codes of length n = pm, where p =+1 mod 8 is a prime.
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