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Chongchong Wang,Liang Yang,Jinglin Li,Hong Zhao,Wanchun Chen 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.4
This paper aims at proposing an entry guidance algorithm for high lift-to-drag ratio entry vehicle, which is based on linear pseudospectral model predictive control and differential flatness theory. The algorithm consists of two phases: descent phase and glide phase. First, the longitudinal plane of the entry process is differentially flat, and the nonlinear system in the longitudinal plane can be transformed into a linear system using the properties of the differential flat system. Then, considering quadratic performance index, the entry longitudinal plane guidance problem is transformed into a linear optimal control problem with terminal constraints. Collocation with Legendre–Gaussian points is used to translate them into a set of algebraic equations. And then, the guidance commands of longitudinal plane, which reduce terminal errors, can be derived in an analytical manner in the form of polynomials. Finally, the heading angle error corridor is used to control the lateral plane motion to obtain the final guidance commands. To evaluate the guidance performance and robustness of the proposed algorithm, nominal trajectory simulation and Monte Carlo simulation were carried out for different target positions. The results show that this method has high computational efficiency, high numerical accuracy, strong adaptability, and robustness, which is applicable for many entry scenarios.
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An Efficient Indexing Structure for Multidimensional Categorical Range Aggregation Query
( Jian Yang ),( Chongchong Zhao ),( Chao Li ),( Chunxiao Xing ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.2
Categorical range aggregation, which is conceptually equivalent to running a range aggregation query separately on multiple datasets, returns the query result on each dataset. The challenge is when the number of dataset is as large as hundreds or thousands, it takes a lot of computation time and I/O. In previous work, only a single dimension of the range restriction has been solved, and in practice, more applications are being used to calculate multiple range restriction statistics. We proposed MCRI-Tree, an index structure designed to solve multi-dimensional categorical range aggregation queries, which can utilize main memory to maximize the efficiency of CRA queries. Specifically, the MCRI-Tree answers any query in O(nkn-1) I/Os (where n is the number of dimensions, and k denotes the maximum number of pages covered in one dimension among all the n dimensions during a query). The practical efficiency of our technique is demonstrated with extensive experiments.
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( Yu Wang ),( Wen Zhou ),( Chongchong Yu ),( Weijun Su ) 한국정보처리학회 2021 Journal of information processing systems Vol.17 No.1
Alzheimer’s disease (AD) is an insidious and degenerative neurological disease. It is a new topic for AD patients to use magnetic resonance imaging (MRI) and computer technology and is gradually explored at present. Preprocessing and correlation analysis on MRI data are firstly made in this paper. Then kernel principal component analysis (KPCA) is used to extract features of brain gray matter images. Finally supervised classification schemes such as AdaBoost algorithm and support vector machine algorithm are used to classify the above features. Experimental results by means of AD program Alzheimer’s Disease Neuroimaging Initiative (ADNI) database which contains brain structural MRI (sMRI) of 116 AD patients, 116 patients with mild cognitive impairment, and 117 normal controls show that the proposed method can effectively assist the diagnosis and analysis of AD. Compared with principal component analysis (PCA) method, all classification results on KPCA are improved by 2%-6% among which the best result can reach 84%. It indicates that KPCA algorithm for feature extraction is more abundant and complete than PCA.
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Block Compressed Sensing of Self-adaptive Measurement and Combinatorial Optimization
Li Mingxing,Chen Xiuxin,Su Weijun,Yu Chongchong 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.5
The block compressed sensing has brought forth the problem that the reconstructed image is of lower quality compared with that of the compressed sensing. A new method is proposed in this paper, named as Block Compressed Sensing of Self-adaptive Measurement and Combinatorial Optimization, which capably solves the problem. According to different sparsity of each image block, we firstly measure the blocks by using different projections; then, we choose measurement with the optimal reconstruction as the final measurement. Eventually, reconstruct the original image using the optimal measurement we got. The proposed method outperforms the compressed sensing in terms of real-time and better reconstruction quality is achieved than the block compressed sensing. Our experimental results verify the superiority of the proposed method.
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Purification and Identification of a Natural Antioxidant Protein from Fertilized Eggs
Shaohua Yang,Lulu Wang,Ying Wang,Xiaoqian Ou,Zhaoyuan Shi,Chongchong Lu,Wei Wang,Guoqing Liu 한국축산식품학회 2017 한국축산식품학회지 Vol.37 No.5
Fertilized hen eggs are rich in a variety of bioactive ingredients. In this study, we aimed to obtain an antioxidant protein from fertilized eggs and the radical scavenging abilities on 1, 1- diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical (•OH), superoxide anion (O2-•) were used to evaluate the antioxidant activity of the purified protein. During 20 d of incubation, the radical scavenging ability of protein extracted from fertilized eggs exhibited significantly differences and the protein on day 16 showed higher antioxidant capacity. Based on this, the antioxidant protein of the samples on day 16 were isolated for the follow-up study. With a molecular weight 43.22 kDa, the antioxidant protein was purified by Diethylaminoethyl cellulose -52 (DEAE-52) column and Sephadex G-100. The LC-MS analysis showed that the purified protein molecular weight was 43.22 kDa, named D2-S. The sequence of amino acids was highly similar to ovalbumin and the coverage reached to 84%. The purified protein showed a radical scavenging rate of 52.34±3.27% on DPPH and 63.49±0.25% on •OH, respectively. Furthermore, the C-terminal amino acid sequence was NAVLFFGRCVSP, which was consistent with the sequence of ovabumin. These results here indicated that purified protein may be a potential resource as a natural antioxidant.
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