检索结果-南通市图书馆

On the convergence of tracking differentiator with multiple stochastic disturbances

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第2期67卷 157-169页

作者： zehao wu Huacheng ZHOU Baozhu GUO Feiqi DENG School of Mathematics and Big Data Foshan University School of Mathematics and Statistics Central South University Academy of Mathematics and Systems Science Chinese Academy of Sciences Systems Engineering Institute South China University of Technology

This paper investigates the convergence, noise-tolerance, and filtering performance of a tracking differentiator in the presence of multiple stochastic disturbances for the first time. We consider a general case wherein the input signal is corrupted by additive colored noise, and the tracking differentiator is disturbed by additive colored noise and white noise. The tracking differentiator is shown to track the input signal and its generalized derivatives in the mean square sense. Further, the almost sure convergence can be achieved when the stochastic noise affecting the input signal is vanishing. Herein, numerical simulations are performed to validate the theoretical results.

关键词： tracking differentiator convergence noise-tolerance filtering performance multiple stochastic disturbances

Effect of Three-High Rotary Piercing Process on Microstructure,Texture and Mechanical Properties of Magnesium Alloy Seamless Tube

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第6期37卷 953-968页

作者： Xiaofeng Ding zehao wu Tong Li Jianxun Chen Yuanhua Shuang Baosheng Liu Heavy Machinery Engineering Research Center of Education Ministry Taiyuan University of Science and TechnologyTaiyuan030024China College of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan030024China

Mg alloy seamless tubes(MASTs)were prepared through three-high rotary piercing process,effect of billet temperature,feed angle and plug advance on microstructure,texture and mechanical properties of tubes were *** effect on the deformation mechanism and improving mechanical properties mechanism of this process for MASTs were *** results show that the grain size could be refined to 11.3-31.1%of the initial grain size and the microstructure was more uniform due to the accumulation of *** formation of high strain gradient at the grain boundary activated the non-basal *** piercing process could change the grain orientation of as-extruded billet and eliminate the initial basal texture to produce new favorable *** the process could accelerate the continuous dynamic recrystallization *** piercing,yield strength of pierced tubes decreased by 6.7%,ultimate tensile strength(UTS)and elongation increased by 32.4 and 45%,respectively,at optimal *** plate-shapedβ_(1)-Mg_(17)Al_(12) orientation transformed from basal plates to prismatic plates,facilitating the increase in UTS and *** decrease size of nanoscale precipitates could reduce the cracking *** critical resolved shear stress ratios of pyramidal(10−11)slip and(11−22)slip to basal slip for the sample including prismatic plates both decreased compared to that including basal *** could enhance the ductility of tube ***,grain boundary sliding could contribute to a better ductility via coordinating deformation and reducing stress concentration during piercing process.

关键词： Mg alloy tube Rotary piercing Microstructure Texture Mechanical properties

水泥分解炉SNCR脱硝系统的深度强化学习多目标优化控制研究

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国电机工程学报 2024年第12期44卷 4815-4825,I0017页

作者：刘定平吴泽豪广东省能源高效低污染转化工程技术研究中心(华南理工大学) 广东省广州市510640

选择性非催化还原(selective non-catalytic reduction,SNCR)脱硝过程的工艺参数优化可以有效减少水泥分解炉NO_(x)排放和脱硝运行成本。以某水泥分解炉为研究对象,建立基于LightGBM的NO_(x)浓度预测模型,以脱硝成本和NO_(x)浓度最小化... 详细信息

选择性非催化还原(selective non-catalytic reduction,SNCR)脱硝过程的工艺参数优化可以有效减少水泥分解炉NO_(x)排放和脱硝运行成本。以某水泥分解炉为研究对象,建立基于LightGBM的NO_(x)浓度预测模型,以脱硝成本和NO_(x)浓度最小化为优化目标,采用深度确定性策略梯度(deep deterministic policy gradient,DDPG)算法对水泥分解炉掺烧污泥协同SNCR脱硝过程的相关工艺参数进行优化控制建模。结果表明,NO_(x)浓度预测模型均方根误差(root mean squared error,RMSE)为6.8,平均绝对百分比误差(mean absolute percentage error,MAPE)为3.48%;采用DDPG算法可以对相关工艺参数进行优化,喷氨量和污泥掺烧量分别为427.87 L/h和9.78 t/h时,NO_(x)排放浓度为225.99 mg/(Nm^(3)),脱硝运行成本为1 747.8元/h。该优化结果与其他优化算法结果和常规工况对比,NO_(x)排放浓度和脱硝运行成本均呈现不同程度下降;对模型进行仿真及效果验证可知,所建立模型能输出合理的喷氨量和污泥掺烧量组合,减少SNCR出口NO_(x)浓度波动,有效降低NO_(x)排放浓度和脱硝成本,可实现对SNCR脱硝系统的多目标优化控制。该结果可为基于智能算法的水泥分解炉SNCR脱硝的多目标优化控制设计提供一定参考。

关键词：喷氨污泥掺烧选择性非催化还原优化控制 LightGBM 强化学习深度确定性策略梯度

Extended state observer for uncertain lower triangular nonlinear systems subject to stochastic disturbance

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Control Theory and Technology 2016年第3期14卷 179-188页

作者： zehao wu Baozhu GUO Key Laboratory of Systems and Control Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

The extended state observer （ESO） is the most important part of an emerging control technology known as active disturbance rejection control to this day, aiming at estimating ＂total disturbance＂ from observable measured output. In this paper, we construct a nonlinear ESO for a class of uncertain lower triangular nonlinear systems with stochastic disturbance and show its convergence, where the total disturbance includes internal uncertain nonlinear part and external stochastic disturbance. The numerical experiments are carried out to illustrate effectiveness of the proposed approach.

关键词： Extended state observer stochastic disturbance lower triangular nonlinear systems

Practical tracking of MIMO uncertain stochastic systems driven by colored noises via active disturbance rejection control

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2022年第6期65卷 203-217页

作者： Chunwan LV Zhengyong OUYANG zehao wu Feiqi DENG Mingqing XIAO School of Mathematics and Big Data Foshan University Systems Engineering Institute South China University of Technology Department of Mathematics Southern Illinois University

This study addresses the practical tracking problem for a class of multi-input multi-output(MIMO) uncertain stochastic systems driven by colored noises via the active disturbance rejection control approach. The extended state observer is designed to estimate in real time the unmeasurable states and the stochastic total disturbance of each subsystem, including unknown coupling system dynamics between subsystems, colored noises, and uncertainty caused by partly unknown control parameters. Active disturbance rejection controllers based on the timely estimation of the extended state observer and compensation are then designed, guaranteeing the mean square practical convergence of the tracking errors. Some numerical simulations are performed to validate the effectiveness of the proposed control strategy.

关键词： uncertain stochastic systems active disturbance rejection control extended state observer tracking colored noise

An inorganic liquid crystalline dispersion with 2D ferroelectric moieties

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2024年第5期11卷 254-263页

作者： Ziyang Huang zehao Zhang Rongjie Zhang Baofu Ding Liu Yang Keyou wu Youan Xu Gaokuo Zhong Chuanlai Ren Jiarong Liu Yugan Hao Menghao wu Teng Ma Bilu Liu Shenzhen Graphene Centre Shenzhen Key Laboratory of Advanced Layered Materials for Value-added ApplicationsTsinghua-Berkeley Shenzhen Institute and Institute of Materials ResearchTsinghua Shenzhen International Graduate School Tsinghua University Institute of Technology for Carbon Neutrality Faculty of Materials Science and Engineering Shenzhen Institute of Advanced Technology Chinese Academy of Sciences School of Physics and Institute for Quantum Science and Engineering School of Chemistry and Institute of Theoretical ChemistryHuazhong University of Science and Technology Xi'an Research Institute of High Technology Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Department of Applied Physics Hong Kong Polytechnic University

Electro-optical effect-based liquid crystal devices have been extensively used in optical modulation techniques, in which the Kerr coefficient reflects the sensitivity of the liquid crystals and determines the strength of the device's operational electric field. The Peterlin–Stuart theory and the O'Konski model jointly indicate that a giant Kerr coefficient could be obtained in a material with both a large geometrical anisotropy and an intrinsic polarization, but such a material is not yet reported. Here we reveal a ferroelectric effect in a monolayer two-dimensional mineral vermiculite. A large geometrical anisotropy factor and a large inherent electric dipole together raise the record value of Kerr coefficient by an order of magnitude, till 3.0 × 10-4mV-2. This finding enables an ultra-low operational electric field of10～2–10～4V m-1and the fabrication of electro-optical devices with an inch-level electrode separation, which has not previously been practical. Because of its high ultraviolet stability（decay <1% under ultraviolet exposure for 1000 hours）, large-scale production, and energy efficiency, prototypical displayable billboards have been fabricated for outdoor interactive scenes. This work provides new insights for both liquid crystal optics and two-dimensional ferroelectrics.

关键词： 2D materials layered minerals vermiculite ferroelectric inorganic liquid crystal Kerr coefficient

Ultrafine ordered L1_(2)-Pt-Co-Mn ternary intermetallic nanoparticles as high-performance oxygen-reduction electrocatalysts for practical fuel cells

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第6期93卷 157-165,I0005页

作者： Enping Wang Liuxuan Luo Yong Feng Aiming wu Huiyuan Li Xiashuang Luo Yangge Guo zehao Tan Fengjuan Zhu Xiaohui Yan Qi Kang Zechao Zhuang Daihui Yang Shuiyun Shen Junliang Zhang China-UK Low Carbon College Shanghai Jiao Tong UniversityShanghai 201306China Institute of Fuel Cells Key Laboratory for Power Machinery and Engineering of MOESchool of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Tangfeng Energy Technology Co.Ltd. Shanghai 201306China State Key Laboratory of Advanced Chemical Power Sources Guizhou Meiling Power Sources Co.Ltd.Zunyi 563003GuizhouChina School of Chemistry and Chemical Engineering Chongqing UniversityChongqing 400044China Institute of New Energy for Vehicles School of Materials Science and EngineeringTongji UniversityShanghai 201804China Department of Chemical Engineering Columbia UniversityNY 10027USA

The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction(ORR)compared to the disordered atomic structures in ordinary solid-solution alloy ***,through a facile and scalable synthetic method,a series of carbon-supported ultrafine Pt_3Co_(x)Mn_(1-x)ternary INPs are prepared in this work,which possess the"skin-like"ultrathin Pt shells,the ordered L1_(2) atomic structure,and the high-even dispersion on supports(L1_(2)-Pt_3Co_(x)Mn_(1-x)/~SPt INPs/C).Electrochemical results present that the composition-optimized L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C exhibits the highest electrocata lytic activity among the series,which are also much better than those of the pristine ultrafine Pt/***,it also has a greatly enhanced electrochemical *** addition,the effects of annealing temperature and time are further *** importantly,such superior ORR electrocatalytic performance of L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C are also well demonstrated in practical fuel *** characterization analyses further reveal the major origins of the greatly enhanced ORR electrocata lytic performance:the Pt-Co-Mn alloy-induced geometric and ligand effects as well as the extremely high L1_(2) atomic-ordering *** work not only successfully develops a highly active and stable ordered ternary intermetallic ORR electrocatalyst,but also elucidates the corresponding"structure-function"relationship,which can be further applied in designing other intermetallic(electro)catalysts.

关键词： Platinum Cobalt Manganese Oxygen reduction reaction Ordered intermetallic L1_(2)atomic structure Proton-exchange membrane fuel cell

基于FasterNet和YOLOv5改进的玻璃绝缘子自爆缺陷快速检测方法

在线全文

学校读者我要写书评

暂无评论

高电压技术 2024年第5期50卷 1865-1876页

作者：邬开俊徐泽浩单宏全兰州交通大学电子与信息工程学院兰州730070

为了实现对电力输电线路中绝缘子缺陷实时快速的巡检需求,提出了一种结合FasterNet-tiny和YOLOv5-s-v6.1网络模型改进的缺陷快速检测算法FasterNet-YOLOv5。首先引入参数量小推理速度更快的FasterNet网络替换原先的CSPDarkNet53主干网络... 详细信息

为了实现对电力输电线路中绝缘子缺陷实时快速的巡检需求,提出了一种结合FasterNet-tiny和YOLOv5-s-v6.1网络模型改进的缺陷快速检测算法FasterNet-YOLOv5。首先引入参数量小推理速度更快的FasterNet网络替换原先的CSPDarkNet53主干网络,加快网络的检测速度。然后结合由GhostNetv2网络提出的解耦全连接注意力机制(decoupled fully connected,DFC),在主干特征提取网络中设计了DFC-FasterNet模块,模块中的DFC Attention机制可以在特征提取过程中增大感受野,提升网络的检测精度。最后针对玻璃绝缘子自爆缺陷目标较小和背景较复杂的情况,重新设计Neck模块,提出BiFPN-F特征融合模块,使网络更精确地定位绝缘子缺陷区域。实验结果表明:改进后的算法可以快速精准定位,其均值平均精度(mean average precision,mAP)达到93.3%,相较于改进前提升5.67%,检测速度达到45.7 Hz,较改进前提升近1倍。同时与最新的YOLOv8n和YOLOv7-tiny相比,改进后的FasterNet-YOLOv5在自爆缺陷上的检测精度和速度更具优势,该文所提算法能够更快速地对绝缘子及其自爆缺陷实时定位识别。

关键词：缺陷检测 BiFPN-F FasterNet YOLOv5s DFC Attention PConv

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

平面S型轴伸贯流泵装置泵内流动特性研究

灌溉排水学报 2023年第3期42卷 90-96页

作者：全莉刘颖吴泽昊严杰扬州市勘测设计研究院有限公司江苏扬州225009

【目的】探究低扬程泵站平面S型泵装置内压力脉动特性和流动稳定性。【方法】采用软件CFX开展三维全流道数值模拟,湍流模型选择为RNG k-ε。采用快速傅里叶变换对压力信号进行处理,在Ansys后处理系统中对流场数据进行可视化处理。分析... 详细信息

【目的】探究低扬程泵站平面S型泵装置内压力脉动特性和流动稳定性。【方法】采用软件CFX开展三维全流道数值模拟,湍流模型选择为RNG k-ε。采用快速傅里叶变换对压力信号进行处理,在Ansys后处理系统中对流场数据进行可视化处理。分析了小流量工况0.8 Qd、设计工况Qd和大流量工况1.2 Qd等3个典型工况下泵装置内的流动特性、压力脉动特性和涡量分布特性。【结果】进水流道内水流流态稳定,流量工况主要影响出水流道内的流动稳定;叶轮内压力脉动激励源为叶轮的旋转作用,在叶轮进口脉动频率成分复杂,主频为叶频;而叶轮出口脉动幅值较小,存在明显的低频脉动;进水流道内水流涡量接近0,叶轮室、导叶室和出水流道内的涡量差别很大,受到叶轮的旋转扰动叶轮室内和导叶室内流场涡量最大。小流量工况下泵段和出水流道内的涡量差异最大,随着流量的增大涡量减小。【结论】涡量分布规律与泵装置内流态变化一致,这从能量的角度解释了不同流量工况下流动稳定差异的原因。研究结果对充分了解平面S型泵装置内流动特性和流动稳定机理提供理论指导,对工程运行提供借鉴意义。

关键词：平面S型轴伸贯流泵涡量压力脉动流动特性数值模拟