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Stable Model Order Reduction Method for Fractional-Order Systems Based on Unsymmetric Lanczos Algorithm

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IEEE/CAA Journal of Automatica Sinica 2019年第2期6卷 485-492页

作者： Zhe gao the College of Light Industry Liaoning University

This study explores a stable model order reduction method for fractional-order systems. Using the unsymmetric Lanczos algorithm, the reduced order system with a certain number of matched moments is generated. To obtain a stable reduced order system, the stable model order reduction procedure is discussed. By the revised operation on the tridiagonal matrix produced by the unsymmetric Lanczos algorithm, we propose a reduced order modeling method for a fractional-order system to achieve a satisfactory fitting effect with the original system by the matched moments in the frequency domain. Besides, the bound function of the order reduction error is offered. Two numerical examples are presented to illustrate the effectiveness of the proposed method.

关键词： Fractional-order systems order reduction stable reduced order systems unsymmetric Lanczos algorithm

不均衡小样本下多特征优化选择的生命体触电故障识别方法

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电工技术学报 2024年第7期39卷 2060-2071页

作者：高伟饶俊民全圣鑫郭谋发福州大学电气工程与自动化学院福州350108 智能配电网装备福建省高校工程研究中心福州350108

针对现有的剩余电流保护装置无法有效识别触电事故的问题,该文提出了一种不均衡小样本下多特征优化选择的生命体触电故障识别方法。首先通过变分自编码器(VAE)对实验收集到的生命体触电小样本数据进行增殖以实现正负样本均衡;然后在时... 详细信息

针对现有的剩余电流保护装置无法有效识别触电事故的问题,该文提出了一种不均衡小样本下多特征优化选择的生命体触电故障识别方法。首先通过变分自编码器(VAE)对实验收集到的生命体触电小样本数据进行增殖以实现正负样本均衡;然后在时域上提取能够反映波形动态变化特性的23个特征量,并利用高斯核Fisher判别分析(GKFDA)与最大信息系数(MIC)法从中选择最优表达特征组;最后,提出基于遗忘因子的在线顺序极限学习机(FOS-ELM)算法实现生命体触电行为的鉴别。实验结果表明,所提方法利用不均衡小样本触电数据集就可以训练出一个优秀的分类模型,诊断准确率可达98.75%,诊断时间仅为1.33 ms。其优良的性能结合在线增量式学习分类器设计,使得模型具备新知识学习能力,具有极好的工程应用前景。

关键词：剩余电流保护装置生命体触电故障多特征优化选择基于遗忘因子的在线顺序极限学习机(FOS-ELM) 不均衡小样本

HEXAGONAL METRIC FOR LINEAR CODES OVER A FINITE FIELD

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Journal of Systems Science & Complexity 2011年第3期24卷 593-603页

作者： Ying gao School of Mathematics and Systems Science Beihang University LMIB of the ministry of Education Beijing 100191 China

This paper consider Hexagonal-metric codes over certain class of finite fields. The Hexagonal metric as defined by Huber is a non-trivial metric over certain classes of finite fields. Hexagonal-metric codes are applied in coded modulation scheme based on hexagonal-like signal constellations. Since the development of tight bounds for error correcting codes using new distance is a research problem, the purpose of this note is to generalize the Plotkin bound for linear codes over finite fields equipped with the Hexagonal metric. By means of a two-step method, the author presents a geometric method to construct finite signal constellations from quotient lattices associated to the rings of Eisenstein-Jacobi （E J） integers and their prime ideals and thus naturally label the constellation points by elements of a finite field. The Plotkin bound is derived from simple computing on the geometric figure of a finite field.

关键词： Constacyclic codes constant weight hexagonal metric Plotkin bound

Earth-moon Trajectory Optimization Using Solar Electric Propulsion

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Chinese Journal of Aeronautics 2007年第5期20卷 452-463页

作者： gao Yang Academy of Opto-Electronics Chinese Academy of Sciences Beijing 100080 China

The optimization of the Earth-moon trajectory using solar electric propulsion is presented. A feasible method is proposed to optimize the transfer trajectory starting from a low Earth circular orbit （500 km altitude） to a low lunar circular orbit （200 km altitude）. Due to the use of low-thrust solar electric propulsion, the entire transfer trajectory consists of hundreds or even thousands of orbital revolutions around the Earth and the moon. The Earth-orbit ascending （from low Earth orbit to high Earth orbit） and lunar descending （from high lunar orbit to low lunar orbit） trajectories in the presence of J2 perturbations and shadowing effect are computed by an analytic orbital averaging technique. A direct/indirect method is used to optimize the control steering for the trans-lunar trajectory segment, a segment from a high Earth orbit to a high lunar orbit, with a fixed thrust-coast-thrust engine sequence. For the trans-lunar trajectory segment, the equations of motion are expressed in the inertial coordinates about the Earth and the moon using a set of nonsingular equinoctial elements inclusive of the gravitational forces of the sun, the Earth, and the moon. By way of the analytic orbital averaging technique and the direct/indirect method, the Earth-moon transfer problem is converted to a parameter optimization problem, and the entire transfer trajectory is formulated and optimized in the form of a single nonlinear optimization problem with a small number of variables and constraints. Finally, an example of an Earth-moon transfer trajectory using solar electric propulsion is demonstrated.

关键词： trajectory optimization solar electric propulsion analytic orbital averaging technique direct/indirect method

The observational constraint on constant-roll inflation

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Science China(Physics,Mechanics & Astronomy) 2018年第7期61卷 38-43页

作者： Qing gao School of Physical Science and Technology Southwest University Chongqing 400715 China

We discuss the constant-roll inflation with constant ∈1 and constant η. By using the method of Bessel function approximation, the analytical expressions for the scalar and tensor power spectra, the scalar and tensor spectral tilts, and the tensor to scalar ratio are derived up to the first order of ∈1. The model with constant ∈2 is ruled out by the observations at the 3σ confidence level, and the model with constant η is consistent with the observations at the 1σ confidence level. The potential for the model with constant η is also obtained from the Hamilton-Jacobi equation. Although the observations constrain the constant-roll inflation to be the slow-roll inflation, the ns-r results from the constant-roll inflation are not the same as those from the slow-roll inflation even when η- 0.01.

关键词： constant-roll inflation cosmological perturbations cosmological constraints

Study on magneto-elastic-plastic deformation characteristics of ferromagnetic rectangular plate with simple supports

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Acta Mechanica Sinica 2009年第1期25卷 139-147页

作者： Yuanwen gao Key Laboratory of Mechanics on Disaster and Environment inWestern China College of Civil Engineering and MechanicsLanzhou University 730000 Lanzhou China

In this paper, the magnetic-elastic-plastic deformation behavior is studied for a ferromagnetic plate with simple supports. The perturbation formula of magnetic force is first derived based on the perturbation technique, and is then applied to the analysis of deformation characteristics with emphasis laid on the analyses of modes, symmetry of deformation and influences of incident angle of applied magnetic field on the plate deformation. The theoretical analyses offer explanations why the configuration offer- romagnetic rectangular plate with simple supports under an oblique magnetic field is in-wavy type along the x-direction, and why the largest deformation of the ferromagnetic plate occurs at the incident angle of 45°for the magnetic field. A numerical code based on the finite element method is developed to simulate quantitatively behaviors of the nonlinearly coupled multi-field problem. Some characteristic curves are plotted to illustrate the magneto--elastic-plastic deflections, and to reveal how the deflections can be influenced by the incident angle of applied magnetic field. The deformation characteristics obtained from the numerical simulations are found in good agreement with the theoretical analyses.

关键词： Ferromagnetic rectangular plate Deformation characteristics Magneto-elastic-plastic coupling - Plastic yield

Influence of the Northeast Cold Vortex on Flooding in Northeast China in Summer 2013

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Journal of Meteorological Research 2018年第2期32卷 172-180页

作者： Jing gao Hui gao Inner Mongolia Climate Center Hohhot 010051 National Climate Center China Meteorological Administration Beijing 100081

Severe flooding occurred in Northeast China（NEC） in summer 2013. Compared with the rainfall climatology of the region, the rainy season began earlier in 2013 and two main rainy periods occurred from late June to early July and from mid July to early August, respectively. During the summer season of 2013, the western Pacific subtropical high（WPSH） was located farther westward, which strengthened the southerly winds on its west side in the lower troposphere. Under this circulation pattern, more water vapor was transported to North China and NEC. Another moisture transport pathway to NEC was traced to the cross-equatorial flow over the Bay of Bengal. In mid–high latitudes in summer 2013, the Northeast Cold Vortex（NECV） was much stronger and remained stable over NEC. Thus, the cold air flow from its northwest side frequently met with the warm and wet air from the south to form stronger moisture convergence at lower levels in the troposphere, resulting in increased precipitation over the region. Correlation analysis indicated that the NECV played a more direct role than the WPSH. Synoptic analyses of the two heaviest flood cases on 2 and 16 July confirmed this conclusion. The four wettest summers in NEC before 2000 were also analyzed and the results were consistent with the conclusion that both the WPSH and the NECV led to the intense rainfall in NEC, but the NECV had a more direct role.

关键词： flood Northeast China Northeast Cold Vortex westem Pacific subtropical high

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西藏产业经济发展耦合协调度分析

高原农业 2025年第1期9卷 133-140页

作者：高坤周芳西藏农牧学院植物科学学院西藏农牧学院资源与环境学院西藏林芝860000

通过选取2011-2021年西藏三大产业总值作为指标数据,运用耦合协调度模型对西藏产业经济发展耦合作用进行实证分析。结果表明,2011-2021年西藏产业经济发展指数总体呈上升趋势,第一产业综合指数年均增长4.5%,依然是西藏经济发展中的基础... 详细信息

通过选取2011-2021年西藏三大产业总值作为指标数据,运用耦合协调度模型对西藏产业经济发展耦合作用进行实证分析。结果表明,2011-2021年西藏产业经济发展指数总体呈上升趋势,第一产业综合指数年均增长4.5%,依然是西藏经济发展中的基础性产业;第二产业综合指数年均增长率为4.1%,其提供的设施保障能力不断加强;第三产业综合指数年均增长高达12.5%,其经济带动效果作用不断提升;西藏三大产业与经济发展的协调度由0.144提高到0.94,总体呈现水平向上的趋势,其协同互动发展机制正不断完善。在未来的发展中,西藏仍需要完善第一产业基础性功能,提升第二产业的自主创新能力,稳定第三产业对经济增长的推动作用,注重产业协调发展,促进西藏经济高质量发展。

关键词：西藏产业经济发展耦合协调度灰色关联度

An artificial immune and incremental learning inspired novel framework for performance pattern identification of complex electromechanical systems

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Science China(Technological Sciences) 2020年第1期63卷 1-13页

作者： WANG RongXi gao Xu gao JianMin gao ZhiYong CHEN Kun PENG CaiYuan State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong UniversityXi'an 710049China Xi'an Thermal Power Research Institute Co. Ltd.Xi'an 710054China

Performance pattern identification is the key basis for fault detection and condition prediction,which plays a major role in ensuring safety and reliability in complex electromechanical systems(CESs).However,there are a few problems related to the automatic and adaptive updating of an identification *** to solve the problem of identification model updating,a novel framework for performance pattern identification of the CESs based on the artificial immune systems and incremental learning is proposed in this paper to classify real-time monitoring data into different performance ***,an unsupervised clustering technique is used to construct an initial identification ***,the artificial immune and outlier detection algorithms are applied to identify abnormal data and determine the type of immune ***,incremental learning is employed to trace the dynamic changes of patterns,and operations such as pattern insertion,pattern removal,and pattern revision are designed to realize automatic and adaptive updates of an identification *** effectiveness of the proposed framework is demonstrated through experiments with the benchmark and actual pattern identification *** an unsupervised and self-adapting approach,the proposed framework inherits the preponderances of the conventional methods but overcomes some of their drawbacks because the retraining process is not required in perceiving the pattern ***,this method can be flexibly and efficiently used for performance pattern identification of the ***,the proposed method provides a foundation for fault detection and condition prediction,and can be used in other engineering applications.

关键词： performance pattern identification complex electromechanical systems artificial immune incremental learning data classification