5篇
您的检索式：作者名="Chunkai Zhang"
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| 1 | A low-energy ion spectrometer with half-space entrance for three-axis stabilized spacecraft显示文摘A low-energy ion spectrometer(LEIS) for use aboard three-axis stabilized spacecraft has been developed to measure ion energy per charge distribution in three-dimensional space with good energy-, angular-and temporal-resolutions. For the standard top-hat electrostatic analyzer used widely in space plasma detection, three-axis stabilized spacecraft makes it difficult to obtain complete coverage of all possible ion arrival directions. We have designed angular scanning deflectors supplementing to a cylindrically symmetric top-hat electrostatic analyzer to provide a half-space field of view as 360°×90°(–45°–+45°), and fabricated the LEIS flight model for detecting magnetospheric ions in geosynchronous orbit. The performance of this payload has been evaluated in detail by a series of simulation and environmental tests, and the payload has also been calibrated through laboratory experiments using a low-energy ion source. The results show that capabilities of the LEIS payload are in accordance with the requirements of a magnetospheric mission. | HU RenXiang SHAN Xu YUAN GuangYuan WANG ShuWen ZHANG WeiHang QI Wei CAO Zhe LI YiRen CHEN ManMing YANG XiaoPing WANG Bo SHAO SiPei LI Feng ZHONG XiaoQing FAN Dan HAO XinJun FENG ChangQing SU ZhenPeng SHEN ChengLong LI Xin DAI GuYue QIU BingLin PAN ZongHao LIU Kai XU ChunKai LIU ShuBin AN Qi ZHANG TieLong WANG YuMing CHEN XiangJun | 2019 | Science China(Technological Sciences)2019，62，6： | 1 |
| 2 | Effect of a second metal (Y, K, Ca, Mn or Cu) addition on the carbon dioxide reforming of methane over nanostructured palladium catalysts显示文摘 | Chunkai Shi Peng Zhang | 2011 | Applied Catalysis B Environmental2011，，： | 1 |
| 3 | Research of Detection Algorithm for Time Series Abnormal Subsequence显示文摘The recent advancements in sensor technology have made it possible to collect enormous amounts of data in real time.How to find out unusual pattern from time series data plays a very important role in data mining.In this paper,we focus on the abnormal subsequence detection.The original definition of discord subsequences is defective for some kind of time series,in this paper we give a more robust definition which is based on the k nearest neighbors.We also donate a novel method for time series representation,it has better performance than traditional methods(like PAA/SAX)to represent the characteristic of some special time series.To speed up the process of abnormal subsequence detection,we used the clustering method to optimize the outer loop ordering and early abandon subsequence which is impossible to be abnormal.The experiment results validate that the algorithm is correct and has a high efficiency. | Chunkai Zhang Haodong Liu Ao Yin | 2017 | 国际计算机前沿大会会议论文集2017，，1： | 0 |
| 4 | A Classification Method of Imbalanced Data Base on PSO Algorithm显示文摘In order to improve the performance of the resampling algorithm in imbalanced data learning and the optimal combination of the weight coefficients of the base classifiers in the ensemble classification algorithm,a new algorithm based on particle swarm optimization(PSO)is proposed.In traditional sampling method,sampling rate is often set artificially.This would make the final classification can’t get a optimal solution.By using the particle swarm optimization algorithm,the sampling rate of the boundary samples and the safety samples are optimized to obtain the optimal over sampling rate self-adaptivly,the weekness of setting sampling rate of traditional method would be overcome. | Junru Lu Chunkai Zhang Fengxing Shi | 2016 | 国际计算机前沿大会会议论文集2016，，2： | 0 |
| 5 | Outsourced Privacy-Preserving Anomaly Detection in Time Series of Multi-Party显示文摘Anomaly detection has practical significance for finding unusual patterns in time series.However,most existing algorithms may lose some important information in time series presentation and have high time complexity.Another problem is that privacy-preserving was not taken into account in these algorithms.In this paper,we propose a new data structure named Interval Hash Table(IHTable)to capture more original information of time series and design a fast anomaly detection algorithm based on Interval Hash Table(ADIHT).The key insight of ADIHT is distributions of normal subsequences are always similar while distributions of anomaly subsequences are different and random by contrast.Furthermore,to make our proposed algorithm fit for anomaly detection under multiple participation,we propose a privacy-preserving anomaly detection scheme named OP-ADIHT based on ADIHT and homomorphic encryption.Compared with existing anomaly detection schemes with privacy-preserving,OP-ADIHT needs less communication cost and calculation cost.Security analysis of different circumstances also shows that OP-ADIHT will not leak the privacy information of participants.Extensive experiments results show that ADIHT can outperform most anomaly detection algorithms and perform close to the best results in terms of AUC-ROC,and ADIHT needs the least time. | Chunkai Zhang Wei Zuo Peng Yang Ye Li Xuan Wang | 2022 | China Communications2022，19，2： | 0 |
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