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Shancheng, China

Ren S.,National University of Defense Technology | Chang W.,National University of Defense Technology | Liu X.,PLA Navy Submarine Academy
Progress In Electromagnetics Research M | Year: 2011

In order to ensure that SAR scene matching aided navigation system can acquire the position errors and yawing errors simultaneously, we propose an image matching algorithm based on Scale Invariant Feature Transform (SIFT). However, the SIFT is proposed for optical image, and its performance degrades when used in SAR image. To enhance the adaptability of SIFT, two ways are employed. One is the application of a preprocessing on image pairs before matching. The other is the establishment of a scale and rotation restriction criteria on tie-points after SIFT matching. Compared with other matching methods, experiment results show that the proposed method is much more suitable for SAR image and successes in matching performance improvement. Furthermore, the method can meet the real-time requirement. Source

Wu H.T.,University of Jinan | Jiang Y.S.,PLA Navy Submarine Academy | Cui Y.J.,University of Jinan | Zhang X.H.,University of Jinan | And 2 more authors.
Journal of Electronic Materials | Year: 2013

Microwave dielectric ceramics based on geikielite-type MgTiO3 were prepared by an aqueous sol-gel process. The precursor powders and dielectric ceramics were characterized by x-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and microwave methods. Highly reactive nanosized magnesium titanate powders with particle sizes of 20 nm to 40 nm were successfully obtained at 500 C as precursors. Sintering characteristics and microwave dielectric properties of MgTiO3 ceramics were studied as a function of sintering temperature from 1100 C to 1300 C. With increasing sintering temperature, the density, ε r, and Qf values increased, saturating at 1200 C with excellent microwave properties of ε r = 17.5, Qf = 156,300 GHz, and τ f = -44 ppm/ C. Correlations between the microstructure and dielectric properties of MgTiO3 ceramics were also investigated. © 2012 TMS. Source

Wu H.T.,University of Jinan | Jiang Y.S.,PLA Navy Submarine Academy | Yue Y.L.,University of Jinan
Ceramics International | Year: 2012

Trirutile-structure MgTa 2O 6 ceramics were prepared by aqueous sol-gel method and microwave dielectric properties were investigated. Highly reactive nanosized MgTa 2O 6 powders were successfully synthesized at 500°C in oxygen atmosphere with particle sizes of 20-40 nm. The evolution of phase formation was detected by DTA-TG and XRD. Sintering characteristic and microwave dielectric properties of MgTa 2O 6 ceramics were studied at different temperatures ranging from 1100 to 1300°C. With the increase of sintering temperature, density, ε r and Q·f values increased and saturated at 1200°C with excellent microwave properties of ε r ∼ 30.1, Q·f ∼ 57,300 GHz and τ f ∼ 29 ppm/°C. The sintering temperature of MgTa 2O 6 ceramics was significantly reduced by aqueous sol-gel process compared to conventional solid-state method. © 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Source

Jiang N.,National University of Defense Technology | Li Z.,PLA Navy Submarine Academy | Yang H.,National University of Defense Technology | Hu Y.,National University of Defense Technology
Guangxue Xuebao/Acta Optica Sinica | Year: 2012

The principle of polarization maintaining fiber (PMF) is analyzed and a three-dimensional model is established by utilizing the finite element method (FEM). The stress distribution and normalized birefringence are obtained through this model. Three pure-optical beat-length measuring systems are carried out for contrastive research and the advantages and disadvantages are described. Experimental results are in good agreement with the theoretical results. Then one simple and effective method to test the beat-length of high-birefringence photonic crystal fiber (Hi-Bi PCF) is chosen and the results indicate that its beat-length is about 1.2 mm. This research provides an effective theoretical method for the analysis of PMF and a convenient experimental system for the beat-length testing of complex structure PMF and Hi-Bi PCF. Source

Zhou M.,Dalian Naval Academy | Chu L.,PLA Navy Submarine Academy
Binggong Xuebao/Acta Armamentarii | Year: 2010

To optimize the torpedo trajectory of acoustic counter-countermeasure for noise jammer, the computing method and the model of jamming direction and distance of high-frequent noise jammer were proposed according to the analyses of jamming mechanism and efficiency direction. The jamming zone at a certain situation was simulated by the model through the example. The simulated results show that reasonable design of torpedo trajectory of acoustic counter-counter measure would enhance the contest effectiveness and the method provides a helpful reference for designing the acoustic countermeasure tactics of submarine and the torpedo trajectory of acoustic counter-countermeasure. Source

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