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Fang Y.,Nanjing Agricultural University | Fang Y.,Zhejiang Provincial Key Laboratory of Forestry Intelligent Monitoring and Information Technology | Lu Z.,Nanjing Agricultural University | Lin L.,Zhejiang Provincial Key Laboratory of Forestry Intelligent Monitoring and Information Technology | Feng H.,Laboratory of Science and Technology on Information Transmission and Dissemination in Communication Networks
ICIC Express Letters, Part B: Applications | Year: 2015

Air-coupled ultrasonic imaging technique is utilized in the nondestructive testing of solid wood board aiming to solve the problem of coupling the sound wave from its generation transducer to material under test (and back to a detection transducer). At first, the correlation between the amplitude of the received signals and the properties of the wood board is presented. The imaging system used in this study is also described. Then experiments were carried out by employing Metasequoia Glyptostroboides board in order to investigate their effect on the transmission of ultrasonic. The parameters of the received signals are highly relevant to the properties of the wood board. Knot, hole, heartwood and sapwood have been shown clearly in the obtained images, allowing the determination of the position, shape and even size. The air-coupled ultrasonic technique has shown promise for nondestructive testing of solid wood board. ©, 2015 ICIC Express Letters Office.All Rights Reserved. Source


Hu J.,Beijing Forestry University | Hu J.,Zhejiang Agriculture And forestry University | Hu J.,Zhejiang Provincial Key Laboratory of Forestry Intelligent Monitoring and Information Technology | Zhou J.,Zhejiang Agriculture And forestry University | And 2 more authors.
International Journal of Earth Sciences and Engineering | Year: 2014

The effect of temperature on the growth and development of plants can’t be ignored. Thus, understanding the distribution of temperature can improve the yield of crops, using the appropriate means of cultivation. In our paper, a quad tree optimized BP neural networks is used to analysis the temperature data collected from Tianmu Mountain of Hangzhou. Through repeated experiments which adopt the optimized BP neural network model, has proved it is sufficient enough to make a trustful temperature prediction, and the prediction based on this model can be applied to other fields with nonlinear features well. © 2014 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved. Source


Gu Z.,Zhejiang University | Zhu X.,Zhejiang University | Wu X.,Zhejiang University | Wu X.,Zhejiang Provincial Key Laboratory of Forestry Intelligent Monitoring and Information Technology | Chen D.,Zhejiang University
Chinese Journal of Sensors and Actuators | Year: 2016

It is simple to estimate the locations of sensor nodes by using the time measurements which are widely used in sensor networks. However there is a drift and deviation of the time clock, which leads to inaccurate time measurement. Based on the clock drift and deviation model, a joint linear estimation method for time synchronization and node localization is proposed, including the least squares (LS) and the weighted least squares (WLS) method. The simulations tested the running time of the designed algorithm and analyzed the impacts of the noises on the estimation error with the joint estimation method. The results show that the LS and WLS linear estimation algorithms run faster than the SDP algorithm, and the LS and WLS linear estimation methods have high stability and accuracy in low noise conditions. © 2016, Editorial Office of Chinese Journal of Sensors and Actuators. All right reserved. Source


Yuan X.,Zhejiang Agriculture And forestry University | Wu X.,Zhejiang Agriculture And forestry University | Wu X.,Zhejiang Provincial Key Laboratory of Forestry Intelligent Monitoring and Information Technology | Wang G.,Zhejiang Agriculture And forestry University | Wang G.,Zhejiang Provincial Key Laboratory of Forestry Intelligent Monitoring and Information Technology
Chinese Journal of Sensors and Actuators | Year: 2014

Based on the localization model with received signal strength indication (RSSI), an accurate localization computation approach of target node position is proposed. Transforming the nonlinear optimization function depicted by RSSI localization model as the estimation problem of linear least square method, the localization results are directly represented as algebraic solutions. The localization approaches of unconstrained linear least square (ULLS) method are proposed with known and unknown transmission power of target node. The parameters of ULLS method are further optimized, then the constrained linear least square (CLLS) method is put forward to improve the localization accuracy. The simulations demonstrate the validity of the localization computation method and test the impacts of signal strength noises on localization error. The results also show that the localization error of CLLS method is less than that of ULLS method and very close to the Cramer-Rao low bound (CRLB) of localization error. ©, 2014, Guojia Jiaowei Quanguo Gaoxiao Chuangan Jishu Yanjiuhui. All right reserved. Source


Wu X.,Zhejiang Agriculture And forestry University | Wu X.,Zhejiang Provincial Key Laboratory of Forestry Intelligent Monitoring and Information Technology | Wang G.,Zhejiang Agriculture And forestry University | Dai D.,Zhejiang Agriculture And forestry University | And 2 more authors.
Journal of Network and Computer Applications | Year: 2014

Energy signal levels received at multiple beacon sensors are proportional to the distances that the signals have traveled to reach the sensors, so the sensor of acoustic source can be uniquely located. Transforming the nonlinear equations to linear equations, LLS, ULSC and CLSC algorithms are all algebraic closed-form solutions for acoustic energy-based localization. We apply these algorithms to acoustic energy-based localization and propose the corresponding best linear unbiased estimator with certain or uncertain beacon positions. The simulations show that LLS and ULSC algorithms have the same position accuracy. Compared with the inferior performance of LLS and ULSC algorithms, CLSC algorithm can attain the position CRLB which provides optimal position accuracy. © 2014 Elsevier Ltd. Source

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