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1

Identity-Based Multi-Proxy Signature Scheme in the Standard Model

Gu K., Jia W., Zhang J.

Fundamenta Informaticae

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2017

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Vol. 150, nr 2

179--210

EN

Multi-proxy signature is a variant of proxy signature, which allows that a delegator (original signer) may delegate his signing rights to many proxy signers. Comparing with proxy signatures, multi-proxy signatures can effectively prevent that some of proxy signers abuse signing rights. Also, with the rapid development of identity-based cryptography, identity-based multi-proxy signature (IBMPS) schemes have been proposed. Comparing with proxy signature based on public key cryptography, IBMPS can simplify key management and be used for more applications. Presently, many identity-based multi-proxy signature schemes have been proposed, but most of them are constructed in the random oracle model. Also, the existing security model for identity-based multi-proxy signature is not enough complete according to the Boldyreva et al.’s work. In this paper, we present a framework for IBMPS on n + 1 users (n is the number of proxy signers participating in signing), and show a detailed security model for IBMPS. Under our framework, we present an identity-based multi-proxy signature scheme in the standard model. Comparing with other identity-based multi-proxy signature schemes, the proposed scheme has more complete security.

2

Automatic tracking of neural stem cells in sequential digital images

Zhang T., Jia W., Zhu Y., Yang J.

Biocybernetics and Biomedical Engineering

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2016

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Vol. 36, no. 1

66--75

EN

Neural stem cells are the cells that give rise to the main cell types of the nervous system. Due to their varying size and shape, and random movement, the tracking of these cells in suspension in video sequences is challenging. This paper develops an automatic tracking system for neural stem cells. The system first detects and localizes cells in the image sequence, followed by a feature extraction step for the subsequent cell tracking. Then, the system tracks inactive cells using an improved mean shift algorithm, divisive cells through a context-based technique, and active cells by means of dynamic local prediction (DLP) and gray prediction (GP) algorithms. Experimental results show that the proposed system not only improves the accuracy of fast moving tracking, but also constructs accurately the trajectories of the cell movement and reduces the iterations during the center searching.

3

Design of one-dimensional dielectric and magnetic photonic crystal filters with broad omnidirectional filtering band

Qiang H., Jiang L., Jia W., Li X.

Optica Applicata

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2011

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Vol. 41, nr 1

63--77

EN

A new kind of one-dimensional (1D) photonic crystal (PC) filter is reported in this paper. This kind of a filter is a dimerlike heterostructure constructed by two 1D dielectric and magnetic PCs. Compared with traditional filters based upon 1D pure dielectric PCs, the new one has the advantage of extending the omnidirectional filtering (ODF) band and simplifying the structure due to its large wave impedance contrast between the composites and the reasonable arrangement of the layer thicknesses and the number of periods. To design such a filter, we adopted a combined method by the transmission matrix method and the decimal genetic algorithm, and finally we obtained a high-precision 1D PC filter design which not only shows a very broad relative ODF band of 1.496, but also has a simple structure with less total number of layers and less total thickness. The simplification of structure is conductive to device fabrication. Besides, an example with low dispersive and low dissipative magnetic material for microwave application is also discussed.

4

Genetic algorithm for band gap optimization under light line in two-dimensional photonic crystal slab

Jia W., Jiang L., Li H., Zheng G., Li X.

Optica Applicata

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2009

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Vol. 39, nr 3

481-488

EN

An optimization algorithm is used to design a two-dimensional photonic crystal slab for large absolute band gaps under light line. In this procedure, the unit cell of the crystal is composed of a number of circular holes in silicon substrate arranged in hexagonal lattice. By optimizing the location and radius of circular hole in the unit cell, we present four designs considering different circular hole numbers. The genetic algorithm finally yielded a photonic crystal with an absolute common band gap of 0.0788(2c/a) at the mid-frequency of 0.3714(2c/a).