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1

Yellowfin tuna (Thunnusalbacares) fishing ground forecasting model based on bayes classifier in the South China Sea

Zhou W., Li A., Ji S., Qiu Y.

Polish Maritime Research

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2017

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S 2

140--146

EN

Using the yellowfin tuna (Thunnusalbacares,YFT)longline fishing catch data in the open South China Sea (SCS) provided by WCPFC, the optimum interpolation sea surface temperature (OISST) from CPC/NOAA and multi-satellites altimetric monthly averaged product sea surface height (SSH) released by CNES, eight alternative options based on Bayes classifier were made in this paper according to different strategies on the choice of environment factors and the levels of fishing zones to classify the YFT fishing ground in the open SCS. The classification results were compared with the actual ones for validation and analyzed to know how different plans impact on classification results and precision. The results of validation showed that the precision of the eight options were 71.4%, 75%, 70.8%, 74.4%, 66.7%, 68.5%, 57.7% and 63.7% in sequence, the first to sixth among them above 65% would meet the practical application needs basically. The alternatives which use SST and SSH simultaneously as the environmental factors have higher precision than which only use single SST environmental factor, and the consideration of adding SSH can improve the model precision to a certain extent. The options which use CPUE’s mean ± standard deviation as threshold have higher precision than which use CPUE’s 33.3%-quantile and 66.7%-quantile as the threshold

2

Nonlinear inverse solution by the look-up table method for Risley-prism-based scanner

Li A., Sun W., Gao X.

Optica Applicata

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2016

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Vol. 46, nr 4

501--515

EN

A pair of rotation Risley prisms can perform superior optical pointing and tracking functions with large visual field and high accuracy. Crucial to the function implementation are the nonlinear inverse solutions to the double-prism orientation angles for tracking a given target trajectory. In the paper, a novel look-up table method is proposed to solve this problem. Because there are two groups of solutions to the rotation angles achieved from an arbitrary target point, a "jump" phenomenon occurs and generates the discontinuous curves of multi-group rotation angle solutions. According to the mapping relation between the coordinate values of the target point and the corresponding rotation angles of two prisms, we can establish the continuous solution curves by adding constraints and employing an optimization algorithm. Experimental results validate the obtained inverse solutions applicable to scan a trajectory close to the given one within an error threshold. The proposed look-up table method can provide foundation for the continuous control of the Risley-prism-based scanner in its inverse applications.Keywords: Risley prism, look-up table method, inverse solution, scanner.

3

Structural analysis of shearing mirror assembly in a lateral double-shearing interferometer

Li A., Luan Z., Jiang X., Bian Y., Wang L., Liu L.

Optica Applicata

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2011

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Vol. 41, nr 3

701--715

EN

By the finite element analysis method, the deformation and stress of the double-shearing mirror assembly is studied to validate the feasibility of the opto-mechanical structure. The side axial deformations (within A400 mm) of the upper semicircular mirror and the lower one are both up to micrometer order along the Y-direction under gravitational action. The equivalent stresses of two semicircular mirrors are more concentrated in the contact areas, but far less than the admissible stress of K9 material. The axial deformations of double-shearing mirror surfaces induced by the temperature rise are very serious, which are the major error sources for the measurement accuracy. The experimental results further validate the analysis conclusions available and show the opto-mechanical design to be reasonable.

4

Integrated design for large-scale opto-mechanical structure

Li A., Bian Y., Liang Y., Zhu Y.

Optica Applicata

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2009

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Vol. 39, nr 2

383-389

EN

An integrated design method is discussed which thoroughly considers related parameters of the various subsystems in order to optimize the overall system that mainly consists of opto-mechanical structure CAD, CAE and the integrated information platform PDM. Based on the parameter drive of the virtual main model, the method focuses on the model transformation and data share among different design and analysis steps, and so the concurrent simulation and design optimization are carried out. As an example of application, the integrated design for a large-scale opto-mechanical structure is introduced, including optical design, structure design and analysis, which further validates the advantages of the method. Due to comprehensive consideration of the design and analysis process by CAD and CAE based on PDM, the integrated design well attains the structure optimization with high efficiency.