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Pseudospectral Model Predictive Control for Exo-atmospheric Guidance
Rahman, Tawfiqur,Zhou, Hao,Yang, Liang,Chen, Wanchun The Korean Society for Aeronautical and Space Scie 2015 International Journal of Aeronautical and Space Sc Vol.16 No.1
This paper suggests applying pseudospectral model predictive method for exo-atmospheric guidance. The method is a fusion of pseudospectral law and model predictive control, in which a two point boundary value problem is formulated using model predictive approach and solved by applying pseudospectral law. In this work, the method is applied to exo-atmospheric guidance with specific target requirement. The existing exo-atmospheric guidance methods suffice general requirements for guidance, but cannot ensure specific target constraints; whereas, the presented method is able to do so. The proposed guidance law is assessed through simulation of perturbed cases, and the tests suggest that the method is able to operate semi-autonomously under control and thrust vector perturbations.
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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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Wang Xianguo,Yao Xiaolu,Zhao Ahui,Yang Mingming,Zhao Wanchun,LeTourneau Melissa K.,Dong Jian,Gao Xiang 한국유전학회 2021 Genes & Genomics Vol.43 No.10
Background Phosphoinositide-specifc phospholipase C proteins mediate environmental stress responses in many plants. However, the potential of PI-PLC genes involved with abiotic stress tolerance in wheat remains un-explored. Objective To study TaPLC1 genetic relation with wheat drought and heat resistance. Methods The seedlings were treated with PI-PLC inhibitor U73122 at the single leaf stage. The seedlings were treated with drought and heat stress at the two leaf stage, and some physiological indexes and the expression profle of TaPLC1 gene were determined. And the TaPLC1 overexpression vector was transferred to Arabidopsis and selected to T3 generation for drought and heat stress treatment. Results After 4 h of drought and heat stress, the SOD activity, MDA and soluble sugar content of the two cultivars with inhibitor were higher than those without inhibitor, the chlorophyll content decreased. CS seedlings showed signifcant wilting phenomenon, and TAM107 showed slight wilting. After the elimination of drought and heat stress, all seedling wilting gradually recovered, while the leaf tips of the two varieties treated with inhibitors began to wilt and turn yellow, which was more signifcant 5 days after the drought and heat stress, while the degree of spring wilting and yellow in CS was earlier than that in TAM107. The expression patterns of TaPLC1 gene were diferent in the two cultivars, but the expression levels reached the maximum at 30 min of heat stress. The change of TaPLC1 expression in TAM107 without inhibitor treatment was signifcantly greater than that in CS. The expression level of TaPLC1 in the two cultivars under stress was signifcantly diferent between the two cultivars treated with inhibitor and untreated, and was lower than that of the normal plants under normal conditions. These results indicated that inhibition of TaPLC1 gene expression could enhance the sensitivity of seedlings to stress. In Arabidopsis, the root lengths of transgenic and wild-type seedlings were shortened after drought stress treatment, but the root lengths of transgenic plants decreased slightly. And the expression of TaPLC1 gene was signifcantly increased after drought and heat stress. This indicated that overexpression of TaPLC1 improved drought resistance of Arabidopsis. Conclusions The results of this study suggest that TaPLC1 may be involved in the regulation mechanism of drought and heat stress in wheat.
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Pseudospectral Model Predictive Control for Exo-atmospheric Guidance
Tawfiqur Rahman,Hao Zhou,Liang Yang,Wanchun Chen 한국항공우주학회 2015 International Journal of Aeronautical and Space Sc Vol.16 No.1
This paper suggests applying pseudospectral model predictive method for exo-atmospheric guidance. The method is a fusion of pseudospectral law and model predictive control, in which a two point boundary value problem is formulated using model predictive approach and solved by applying pseudospectral law. In this work, the method is applied to exo-atmospheric guidance with specific target requirement. The existing exo-atmospheric guidance methods suffice general requirements for guidance, but cannot ensure specific target constraints; whereas, the presented method is able to do so. The proposed guidance law is assessed through simulation of perturbed cases, and the tests suggest that the method is able to operate semi-autonomously under control and thrust vector perturbations.
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Wan, Chun,Shen, Yong-Chun,Liu, Meng-Qi,Yang, Ting,Wang, Tao,Chen, Lei,Yi, Qun,Wen, Fu-Qiang Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.9
The diagnosis of malignant mesothelioma (MM) remains a clinical challenge and the fluorescence in situ hybridization (FISH) assay has been reported to be one promising tool. The present meta-analysis aimed to establish the overall diagnostic accuracy of FISH for diagnosing MM. After a systematic review of English language studies, the sensitivity, specificity and other measures of accuracy of FISH in the diagnosis of MM were pooled using random-effects models. Summary receiver operating characteristic curves were applied to summarize overall test performance. Nine studies met our inclusion criteria, the pooled sensitivity and specificity for FISH for diagnosing MM being 0.72 (95% CI 0.67-0.76) and 1.00 (95% CI 0.98-1.00), respectively. The positive likelihood ratio was 34.5 (95% CI 14.5-82.10), the negative likelihood ratio was 0.24 (95% CI 0.16-0.36), and the diagnostic odds ratio was 204.9 (95% CI 76.8-546.6), the area under the curve being 0.99. Our data suggest that the FISH assay is likely to be a useful diagnostic tool for confirming MM. However, considering the limited studies and patients included, further large scale studies are needed to confirm these findings.
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