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Aero-thermal heating constrained midcourse guidance using state-constrained model predictive static programming method

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Journal of Systems Engineering and Electronics 2018年第6期29卷 1263-1270页

作者： fu Bin GUO Hang CHEN kang fu Wenxing WU Xingyu YAN Jie School of Astronautics Northwestern Polytechnical UniversityXi’an 710072China Xi’an Microelectronic Technology Institute Xi’an 710065China

This paper proposes a multiple-constraints-guaranteed midcourse guidance law for the interception of the hypersonic targets. In traditional midcourse law design, the constraints of the aero-thermal heating are rarely taken into consideration. The performance of the infrared detection system may be degraded and the instability of the flight control system may be *** address this problem, a state-constrained model predictive static programming method is introduced such that both terminal constraints(position and angle) and optimal energy consumption can be ensured. As a result, a sub-optimal midcourse guidance,guaranteeing the aforementioned multiple-constraints to be never violated, is synthesized. Simulation results demonstrate the effectiveness of the proposed method.

关键词： midcourse guidance model predictive control optimal control state constraint

Measuring reliability under epistemic uncertainty:Review on non-probabilistic reliability metrics

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Chinese Journal of Aeronautics 2016年第3期29卷 571-579页

作者： kang Rui ZhangQingyuan zeng Zhiguo Enrico Zio Li Xiaoyang School of Reliability and Systems Engineering Beihang UniversityBeijing 100083China Energy Department Politecnico di MilanoMilano 20133Italy Chair on Systems Science and Energy Challenge Fondation Electricite'de France(EDF)Centrale SupelecUniversite'Paris-SucluyChatenay-MalabryParis 92290France

In this paper, a systematic review of non-probabilistic reliability metrics is conducted to assist the selection of appropriate reliability metrics to model the influence of epistemic uncertainty. Five frequently used non-probabilistic reliability metrics are critically reviewed, i.e., evidence- theory-based reliability metrics, interval-analysis-based reliability metrics, fuzzy-interval-analysis- based reliability metrics, possibility-theory-based reliability metrics （posbist reliability） and uncertainty-theory-based reliability metrics （belief reliability）. It is pointed out that a qualified reli- ability metric that is able to consider the effect of epistemic uncertainty needs to （ 1 ） compensate the conservatism in the estimations of the component-level reliability metrics caused by epistemic uncertainty, and （2） satisfy the duality axiom, otherwise it might lead to paradoxical and confusing results in engineering applications. The five commonly used non-probabilistic reliability metrics are compared in terms of these two properties, and the comparison can serve as a basis for the selection of the appropriate reliability metrics.

关键词： Belief reliability Epistemic uncertaintyEvidence theory Interval analysis Possibility theory Probability box Reliability metrics Uncertainty theory

Bayesian Estimation and Model Selection for the Spatiotemporal Autoregressive Model with Autoregressive Conditional Heteroscedasticity Errors

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Acta Mathematicae Applicatae Sinica 2023年第4期39卷 972-989页

作者： Bing SU fu-kang ZHU Ju HUANG Department of Statistics&Actuarial Science University of Hong KongHong Kong 999077China School of Mathematics Jilin UniversityChangchun 130012China National Energy Administration Information Center Beijing 100045China

The spatial and spatiotemporal autoregressive conditional heteroscedasticity(STARCH) models receive increasing attention. In this paper, we introduce a spatiotemporal autoregressive(STAR) model with STARCH errors, which can capture the spatiotemporal dependence in mean and variance simultaneously. The Bayesian estimation and model selection are considered for our model. By Monte Carlo simulations, it is shown that the Bayesian estimator performs better than the corresponding maximum-likelihood estimator, and the Bayesian model selection can select out the true model in most times. Finally, two empirical examples are given to illustrate the superiority of our models in fitting those data.

关键词： autoregressive conditional heteroscedasticity model Bayesian estimation model selection spatial ARCH model spatial panel model spatiotemporal model

Control for a Class of Stochastic Mechanical Systems Based on the Discrete-Time Approximate Observer

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Journal of Systems Science & Complexity 2019年第2期32卷 526-541页

作者： fu Xinxin kang Yu LI Pengfei YU Peilong Department of Automation University of Science and Technology of China

This paper investigates the observer-based control problem of a class of stochastic mechanical systems. The system is modelled as a continuous-time It o stochastic differential equation with a discrete-time output. Euler-Maruyama approximation is used to design the discrete-time approximate observer, and an observer-based feedback controller is derived such that the closed-loop nonlinear system is exponentially stable in the mean-square sense. Also, the authors analyze the convergence of observer error when the discrete-time approximate observer servers as a state observer for the exact system. Finally, a simulation example is used to demonstrate the effectiveness of the proposed method.

关键词： Approximate model discrete-time observer exponential stability stochastic nonlinear system

Nonlinearity analysis of piezoelectric micromachined ultrasonic transducers based on couple stress theory

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Acta Mechanica Sinica 2012年第1期28卷 104-111页

作者： Xin kang fu-Jun Yang Xiao-Yuan He Department of Applied Mechanics Nanjing University of Science and Technology210094 NanjingChina Department of Mechanical and Aeronautical Engineering University of CaliforniaDavis95616US Institute of Engineering Mechanics Southeast University210096 NanjingChina

This paper studies the static deformation behavior of a piezoelectric micromachined ultrasonic transducer （PMUT） actuated by a strong external electric field. The transducer membrane consists of a piezoelectric layer, a passive layer and two electrode layers. The nonlinearities of the piezoelectric layer caused by electrostriction under a strong electric field are analyzed. Because the thickness of the transducer membrane is on the microscale, the size dependence of the deformation behavior is evaluated using the couple stress theory. The results show that the optimal ratio of the top electrode diameter and the membrane diameter is around 0.674. It is also found that this optimal value does not depend on any other parameters if the thicknesses of the two electrodes are negligible compared with those of the piezo- electric and passive layers. In addition, the nonlinearities of the piezoelectric layer will become stronger along with the increase of the electric field, which means that softening of the membrane stiffness occurs when a strong external electric field is applied. Meanwhile, the optimal thickness ratio for the passive layer and the piezoelectric layer is not equal to 1.0 which is usually adopted by previous researchers. Because there exists size dependence of membrane deforma-tion, the optimal value of this thickness ratio needs to be greater than 1.0 on the microscale.

关键词： Piezoelectric micromachined ultrasonic trans- ducer (PMUT) Couple stress theory Static deformation - Nonlinearity analysis

A serialized civil aircraft R&D cost estimation model considering commonality based on BP algorithm

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Chinese Journal of Aeronautics 2022年第4期35卷 253-265页

作者： Yongjie ZHANG kang CAO Ke LIANG Yongqi zeng Wenjun DONG School of Aviation.Northwestern Polytechnical University Xi'an 710072China Shanghai Aircraft Design and Research Institute Shanghai 201210China

The common design of serial civil aircraft, an important strategy of modern civil aircraft research and develop-ment, minimizes the whole life cycle cost of civil aircraft through asset reuse and resource sharing. However, the existing estimating model for the R&D cost of civil aircraft ignores the effects of common design, so the value estimated by estimating derivative models is significantly inconsistent with the actual one. To solve this problem, a novel assessment method for civil aircraft commonality indicators is developed based on fuzzy set in the present study, exploiting the attributes and structural parameters of the aircraft to be assessed as input to determine the degree of membership that pertains to the commonality sub-interval as the commonality *** the BP(Back Propagation) neural network algorithm is adopted to establish the relationship between the common index and the decrease rate of the R&D cost of derivative models. The model employs over a dozen typical civil aircraft models(e.g., Boeing, Airbus, and Bombardier) as the sample data for network learning training to build a mature neural network model for estimating the R&D cost of novel derivative models. As revealed from the comparative analysis on the calculated results of the samples, the estimated results of the model given the effects of commonality in the present study exhibit higher estimation accuracy and value for future work.

关键词： BP algorithm Civil aircraft R&D cost Common indicators fuzzy set Serialized civil aircraft

Machine learning and a computational fluid dynamic approach to estimate phase composition of chemical vapor deposition boron carbide

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Journal of Advanced Ceramics 2021年第3期10卷 537-550页

作者： Qingfeng zeng Yong GAO kang GUAN Jiantao LIU Zhiqiang FENG Science and Technology on Thermostructural Composite Materials Laboratory School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China MSEA International Institute for Materials Genome Gu’an 065500China School of Materials Science and Engineering South China University of TechnologyGuangzhou 510640China School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China eSchool of Mechanics and Engineering Southwest Jiaotong UniversityChengdu 610031China LMEE-UEVE UniversitéParis-SaclayEvry 91020France

Chemical vapor deposition is an important method for the preparation of boron *** of the correlation between the phase composition of the deposit and the deposition conditions (temperature,inlet gas composition,total pressure,reactor configuration,and total flow rate) has not been completely *** this work,a novel approach to identify the kinetic mechanisms for the deposit composition is *** leaning (ML) and computational fluid dynamic (CFD) techniques are utilized to identify core factors that influence the deposit *** has been shown that ML,combined with CFD,can reduce the prediction error from about 25% to 7%,compared with the ML approach *** sensitivity coefficient study shows that BHCl_(2 )and BCl_(3) produce the most boron atoms,while C_(2)H_(4) and CH_(4) are the main sources of carbon *** new approach can accurately predict the deposited boron-carbon ratio and provide a new design solution for other multi-element systems.

关键词： machine learning(ML) computational fluid dynamic(CFD) chemical vapor deposition boron carbide B/C ratio kinetic mechanisms

巩固、发展与抗日:中央红军东征期间与各方势力之周旋

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河北学刊 2025年第1期45卷 218-224页

作者：郑康奇南开大学历史学院

1935年底,红军在陕北会师后积极进行扩红与筹粮运动。与此同时,中共中央审时度势决定进行东征,以图缓解陕北地区兵员、粮源的紧张局面。1936年2至5月,中央红军东渡黄河与阎锡山部作战,蒋介石也借机派兵进入山西。在红军东征的过程中,双... 详细信息

1935年底,红军在陕北会师后积极进行扩红与筹粮运动。与此同时,中共中央审时度势决定进行东征,以图缓解陕北地区兵员、粮源的紧张局面。1936年2至5月,中央红军东渡黄河与阎锡山部作战,蒋介石也借机派兵进入山西。在红军东征的过程中,双方高层展开了一系列的斗争与博弈。中共在东征中积极争取张学良与杨虎城部,统一战线策略取得了成功。这一时期,国际政治局势变幻莫测,中国共产党与共产国际的关系也产生了一些微妙变化。在与国际国内各方的政治博弈中,中共的政策逐渐走向成熟,为第二次国共合作奠定了重要基础。

关键词：红军东征扩红政治势力抗日战争

In situ construction of Cu(Ⅰ)-Cu(Ⅱ) pairs for efficient electrocatalytic nitrate reduction reaction to ammonia

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Journal of Energy Chemistry 2025年第1期 106-113页

作者： Muyun Zheng Yuchi Wan Leping Yang Shen Ao Wangyang fu Zhengjun Zhang Zheng-Hong Huang Tao Ling Feiyu kang Ruitao Lv State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Institute of New Energy Materials and Engineering School of Materials Science and Engineering Fuzhou University Key Laboratory of Advanced Materials (MOE) School of Materials Science and Engineering Tsinghua University Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education Tianjin Key Laboratory of Composite and Functional Materials School of Materials Science and Engineering Tianjin University

Electrocatalytic nitrate reduction reaction （NO3-RR） to ammonia under ambient conditions is expected to be a green process for ammonia synthesis and alleviate water pollution *** report a CuO nanoparticles incorporated on nitrogen-doped porous carbon （CuO@NC） catalyst for *** of Cu（Ⅱ） is reduced to Cu（Ⅰ） during the NO3-RR process to construct Cu（Ⅰ）-Cu（Ⅱ） pairs,confirmed by in situ X-ray photoelectron spectroscopy （XPS） and Raman *** functional theory （DFT） calculations indicated that the formation of Cu（Ⅰ） could provide a reaction path with smaller energy barrier for NO3-RR,while Cu（Ⅱ） effectively suppressed the competition of hydrogen evolution reaction （HER）.As a result,CuO@NC catalyst achieved a Faradaic efficiency of 84.2% at -0.49 V versus reversible hydrogen electrode （RHE）,and a NH3yield rate of 17.2 mg *** -0.79 V ***,higher than the HaberBosch process (<3.4 g h-1g-1cat.).This work may open a new avenue for effective NO3-RR by modulating oxidation states.

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