Online Hop Timing Detection and Frequency Estimation of Multiple FH Signals

Zhi-Chao Sha,Zhang-Meng Liu,Zhi-Tao Huang,Yi-Yu Zhou 한국전자통신연구원 2013 ETRI Journal Vol.35 No.5

This paper addresses the problem of online hop timing detection and frequency estimation of multiple frequencyhopping (FH) signals with antenna arrays. The problem is deemed as a dynamic one, as no information about the hop timing, pattern, or rate is known in advance, and the hop rate may change during the observation time. The technique of particle filtering is introduced to solve this dynamic problem, and real-time frequency and direction of arrival estimates of the FH signals can be obtained directly, while the hop timing is detected online according to the temporal autoregressive moving average process. The problem of network sorting is also addressed in this paper. Numerical examples are carried out to show the performance of the proposed method.

A Construction Method of Gene Expression Data Based on Information Gain and Extreme Learning Machine Classifier on Cloud Platform

Wei Sha-Sha,Lu Hui-Juan,Jin Wei,Li Chao 보안공학연구지원센터 2014 International Journal of Database Theory and Appli Vol.7 No.2

Detecting the Hierarchical Community Structure Based on Advanced LPA

Pengtao Jia,Sha Chao,Shuang Qiu 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.8

LPA is a classical community detection algorithm with linear time complexity. It can be applied to networks whose community structure is known. However, the randomness of it's initial nodes causes a poor stability. In this paper, we proposed a new method to improve the algorithm by reordering the initial nodes. The advanced algorithm uses ascending order instead of descending order based on degree. It can improve the stability of the original algorithm and detect the hierarchical community structure of the complex network. We tested the algorithm on Zachary's karate network, Dolphins social network and American football network. The experiments confirmed that compared to the classical algorithm the improved algorithm has better performance in terms of rationality and accuracy.

Robust Unit Commitment with Virtual Synchronous Renewables

Zhang Wei-Chao,Sheng Wanxing,Duan Qing,Sha Guanglin,Zhang Yao,Huang Hanyan,Yan Xiangwu 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.6

With the increasing penetration of renewable energy sources and the consequent displacement of synchronous generators, the frequency stability of power systems deteriorates since RESs cannot participate in active power and frequency control. By emulating the outer characteristics of SGs and deloading a controllable margin, RESs can also keep headroom and provide frequency responses. This paper focuses on incorporating virtual synchronous renewables into the unit commitment to optimize the joint scheduling of energy production and spinning reserves. First, based on the interval representation of renewable uncertainty, the renewable output is decomposed into the stochastic and dispatchable portions. The dispatchable portion, defi ned as VSRs, can keep deterministic regulation headroom and participate in power balance regulation. Second, a robust security-constrained unit commitment model is proposed to achieve optimal scheduling in face of multiple uncertainties. The fl exibility of the pumped-storage hydro station is also considered. Third, the solution strategies which linearize the nonlinear terms in the objective function and constraints are introduced. Finally, the correctness and eff ectiveness of the robust unit commitment model are tested and verifi ed in the modifi ed 39-bus system.

Pore evolution characteristics of Chinese marine shale in the thermal simulation experiment and the enlightenment for gas shale evaluation in South China

Huiying Cui,Feng Liang,Chao Ma,Ningning Zhong,Yuliang Sha,Wei Ma 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.4

Although there are many similarities between the shale of Cambrian Qiongzhusi Formation and Ordovician Wufeng Formation–Silurian Longmaxi Formation in South China, including total organic carbon content (TOC) and thickness, the drilling results of shale gas exploration are very different. One of the reasons is the difference of the nano-pores number developed in organic matter between them. In order to reveal the causes, the black shale of Upper Proterozoic Xiamaling Formation in North China, which is similar to the marine source rock in Sichuan basin, was selected for the thermal simulation experiment, and the pore size and volume of the samples before and after the experiment were acquired by scanning electron microscopy (SEM) and nitrogen adsorption isotherm measurement. Through the SEM photographs, we found that the sizes of the organic pores in algae, dispersed organic matter and organic matter associated with clay minerals get bigger with the increasing maturity. The total pore volume, micro-pore volume and meso-pore volume of the shale acquired by nitrogen adsorption isotherm measurement increase with the increasing maturity, too. However, under the overburden pressure, micro-pore volume decreases at high maturity stage, indicating the pores in organic matter might be compressed. It is considered that the pore volume in organic matter of the shale of Qiongzhusi Formation might be compacted under greater confining pressure, which may be the reason why the pore structures of the two sets of marine shale in South China are different.

Study on flexible two-axis roll-bending process for component with non-circular section

Tao Zhang,Huapu Sha,Shihong Lu,Chao Du,Peng Chen 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.9

Two-axis roll-bending technology, with the advantages of small curvature radius, short straight section and high efficiency, is widely used in fields of aerospace and automobile. By adjusting indentation depth in two-axis roll-bending process, different curvature radius of circular and elliptic component can be formed. Roll-bending experiments and numerical simulations for component with circular and elliptic section are conducted. The results show that the forming curvature radius of circular component and its deviation both decrease with ascending indentation depth. The relationship between forming curvature radius and indentation depth is polynomial fitted. On this basis, ellipse parameter equation is established and different curvature radius at different position of the ellipse is achieved by adjustment of indentation depth. The relationship between indentation depth and forming time is obtained for elliptic component. Elliptic components with different sizes are formed. The stress distribution is uniform after roll-bending process and it increases with ascending indentation depth.

Identification of mountain-cultivated ginseng and cultivated ginseng using UPLC/oa-TOF MSE with a multivariate statistical sample-profiling strategy

Xu, Xin-fang,Cheng, Xian-long,Lin, Qing-hua,Li, Sha-sha,Jia, Zhe,Han, Ting,Lin, Rui-chao,Wang, Dan,Wei, Feng,Li, Xiang-ri The Korean Society of Ginseng 2016 Journal of Ginseng Research Vol.40 No.4

Background: Mountain-cultivated ginseng (MCG) and cultivated ginseng (CG) both belong to Panax ginseng and have similar ingredients. However, their pharmacological activities are different due to their significantly different growth environments. Methods: An ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS)-based approach was developed to distinguish MCG and CG. Multivariate statistical methods, such as principal component analysis and supervised orthogonal partial-least-squares discrimination analysis were used to select the influential components. Results: Under optimized UPLC-QTOF-MS/MS conditions, 40 ginsenosides in both MCG and CG were unambiguously identified and tentatively assigned. The results showed that the characteristic components of CG and MCG included ginsenoside Ra3/isomer, gypenoside XVII, quinquenoside R1, ginsenoside Ra7, notoginsenoside Fe, ginsenoside Ra2, ginsenoside Rs6/Rs7, malonyl ginsenoside Rc, malonyl ginsenoside Rb1, malonyl ginsenoside Rb2, palmitoleic acid, and ethyl linoleate. The malony ginsenosides are abundant in CG, but higher levels of the minor ginsenosides were detected in MCG. Conclusion: This is the first time that the differences between CG and MCG have been observed systematically at the chemical level. Our results suggested that using the identified characteristic components as chemical markers to identify different ginseng products is effective and viable.