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Short-Term Forecasting for Harbor Waterway Currents Speeds
Cheng Gong,Yan Lv,Chunjiang Zhang,Xiyuan Wang,Wei Huangfu,Zhongshan Zhang 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.12
The ocean currents speeds in the harbor waterway are directly related to the ability of the ship to in or out the harbor. Accurately predict the speeds can assist the ship to choose the right time for sailing. To solve this problem, we chose two models of linear and non-linear prediction. We had set sensors in Qinhuangdao for a long time, then using the collected data for training. Our test is using a lot of random data to train and predict with different steps and orders. The results show that both methods can use less original data to train the model, and finally achieve preferably prediction. According to the characteristics of Qinhuangdao harbor, Auto-Regressive (AR) model is more appropriate than Support Vector Regression (SVR) model.
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Emergency Broadcasting over CATV Channel using FM Subcarrier Technology
Yan Ma,Chunjiang Liu,SenHua Ding,Naiguang Zhang 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.12
Emergency broadcasting is of importance method to alert people when disaster happens, but the development of network is slow in Chinese rural areas. So it is necessary to propose an emergency broadcasting solution for Chinese rural areas based on the available network. In this paper, a method that adopts FM subcarrier technology over CATV channel to broadcast emergency message have been proposed. In the method, emergency program is transmitted by CATV channel and emergency order is carried in FM subcarrier. As usual, to communicate emergency message to the public efficiently and effectively, a complete emergency broadcasting system should have following functions such as parallel broadcasting, compatibility, robustness, security, and so on. In the context, to satisfy above requirements, corresponding system construction, communication scheme, and message transmission protocol have been proposed as well. To verify the practicability, the solutions have been test in Chinese rural areas MiYun and gain good results.
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Non-devastating Islanding Detection for Micro-grid Based on Mathematical Statistics
Xiaohuan Wang,Chunjiang Zhang,Wenchao Zhao,Xiao Mu 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Conventional passive islanding detection methods have disadvantages of non-detection zone (NDZ). Active ones can reduce or eliminate NDZ, but their operation mechanism is forcing the voltage or frequency into the fault range, which is a devastating islanding detection approach. However, the non-devastating islanding method without NDZ is desirable for micro-grid applications. A novel active islanding detection method based on mathematical statistics for three-phase inverter is proposed. In this paper, 0-1 sequence is used to modulate the PWM modulation wave by amplitude adjustment. Then the voltage of point of common coupling (PCC) is sampled and the variance based on mathematics features is calculated in real-time. According to the value of variance, the islanding can be determined. The proposed method not only conquers the disadvantage of the destroy that conventional active islanding detection methods result in to the utility grid, but also detects the islanding effectively when the DG power production match to the load power requirement. And it is quick and effective under the ideal and non-ideal utility grid and the false islanding also can be prevented. Simulation and experiment results verify the correctness and feasibility of the proposed method. This method is suitable for the grid-connected /stand-alone dual-mode micro-grid system.
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Hongyang Qing,Chunjiang Zhang,Xiuhui Chai,Hao He,Xiaohuan Wang 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.6
When a three-phase four-wire grid-connected energy storage inverter is connected to unbalanced or single-phase loads, a large grid-connected harmonic current is generated due to the existence of a zero-sequence channel. A controller design approach for grid-connected harmonic current suppression is proposed based on proportion–integral–repetitive (PI–repetitive) control for a three-level neutral point clamped (3L-NPC) three-phase four-wire inverter. By designing the variable parameters n (gain coeffi cient of the PI controller) and Qs (gain of the repetitive controller), the eff ect of the PI–repetitive controller gain on current harmonic suppression is analyzed using a three-dimensional amplitude gain curve. A simplifi ed impedance model in the d 0-frame for a three-phase four-wire inverter is proposed. Based on the impedance model in the d0-frame, the system stability is analyzed under diff erent PI–repetitive control gains by the generalized Nyquist criterion. Finally, the optimal controller design is obtained by a gain characteristic and system stability analysis. The controller obtained by this harmonic suppression analysis method can simultaneously ensure the best grid-connected current quality of the three-phase four-wireinverter and the dynamic stability of the system. Simulation and experimental results verify the effectiveness and correctness of the proposed controller design approach for grid-connected harmonic current suppression.
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Yao, Yuchang,Cai, Zhaowei,Zhang, Lifan,Zhao, Chunjiang,Wu, Keliang,Xu, Ningying,Liu, Gang,Wu, Changxin Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.8
Castration of male pig produces significant negative effects on skeletal muscle development. The androgen receptor (AR), two splice variants of insulin-like growth factor-I (IGF-I Ea and MGF) and the myostatin gene may play important roles in this process. In the present study, the expression of AR, IGF-I Ea, MGF and myostatin genes in three skeletal muscles, the brachialis, longissimus and semitendinosus, were studied using real-time quantitative RT-PCR. Our experimental design used 14 pairs of male Landrace sire${\times}$Yorkshire dam piglets. The two piglets in each pair were full sibs, one of which was castrated at 21 d of age; the other remained intact. The study group was divided into subgroups of equal size. Animals in the first subgroup were slaughtered at 147 d and those of the second at 210 d of age. Carcass weight and lean meat yield were similar between boars and barrows at 147 d of age (p>0.05), whereas barrows had lower carcass weight and less lean meat yield at 210 d of age (p<0.05). Castration caused down-regulation of AR gene expression at both 147 and 210 d of age (p<0.05). The two splice variants of the IGF-I gene from porcine skeletal muscle were cloned using RT-PCR, and it was found that MGF differs from IGF-I Ea in having a 52-base insert in the last coding exon of the mRNA. Both splice variants were down-regulated by castration only at 210 d of age (p<0.05). No differences in expression of the myostatin gene were observed between boars and barrows at either 147 or 210 d of age (p>0.05). These results suggest that the downregulation of AR, IGF-I Ea and MGF gene expression following castration helps to explain the negative effect of castration on skeletal muscle development.
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