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FIR system identification with set-valued and precise observations from multiple sensors

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Science China(Information Sciences) 2019年第5期62卷 179-194页

作者： hang Zhang Ting wang Yanlong ZHAO Key Laboratory of Systems and Control Academy of Mathematics and Systems ScienceChinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences

This paper considers the system identification problem for FIR(finite impulse response) systems with set-valued and precise observations received from multiple sensors. A fusion estimation algorithm based on some suitable identification algorithms for different types of observations is proposed. In particular, least square method is chosen for FIR systems with precise observations, while empirical measure method and EM algorithm are chosen for FIR systems with set-valued observations in the cases of periodic and general system inputs, respectively. Then, the quasi-convex combination estimator(QCCE) fusing the two different estimators by a linear combination with appropriate weights is constructed. Furthermore, the convergence properties are theoretically analyzed in terms of strong consistency and asymptotic efficiency. The fused estimator QCCE is proved to achieve the Cram′er-Rao(CR) lower bound asymptotically under periodic inputs. Extensive numerical simulations validate the superiority of the fusion estimation algorithm under both periodic and general inputs.

关键词： system identification FIR system set-valued precise fusion estimation quasi-convex combination estimator

Methane reforming with CO_2 to syngas over CeO_2-promoted Ni/Al_2O_3-ZrO_2 catalysts prepared via a direct sol-gel process

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Journal of Natural Gas Chemistry 2011年第1期20卷 1-8页

作者： Hansheng Li hang Xu Jinfu wang School of Chemical Engineering and the Environment Beijing Institute of Technology Beijing 100081 China Department of Chemical Engineering Tsinghua University Beijing 100084 China

CeO2-promoted Ni/Al2O3-ZrO2 （Ni/Al2O3-ZrO2-CeO2） catalysts were prepared by a direct sol-gel process with citric acid as gelling agent. The catalysts used for the methane reforming with CO2 was studied by infrared spectroscopy （IR）, thermal gravimetric analysis （TGA）, microscopic analysis, X-ray diffraction （XRD） and temperature-programmed reduction （TPR）. The catalytic performance for CO2 reforming of methane to synthesis gas was investigated in a continuous-flow micro-reactor under atmospheric pressure. TGA, IR, XRD and microscopic analysis show that the catalysts prepared by the direct sol-gel process consist of Ni particles with a nanostructure of around 5 nm and an amorphous-phase composite oxide support. There exists a chemical interaction between metallic Ni particles and supports, which makes metallic Ni well dispersed, highly active and stable. The addition of CeO2 effectively improves the dispersion and the stability of Ni particles of the prepared catalysts, and enhances the adsorption of CO2 on the surface of catalysts. The catalytic tests for methane reforming with CO2 to synthesis gas show that the Ni/Al2O3-ZrO2-CeO2 catalysts show excellent activity and stability compared with the Ni/Al2O3 catalyst. The excellent catalytic activity and stability of the Ni/Al2O3-ZrO2-CeO2 are attributed to the highly, uniformly and stably dispersed small metallic Ni particles, the high reducibility of the Ni oxides and the interaction between metallic Ni particles and the composite oxide supports.

关键词： methane reforming with CO2 syngas Ni-based catalyst CeO2 sol-gel process

High-entropy intermetallics:from alloy design to structural and functional properties

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Rare Metals 2022年第6期41卷 1989-2001页

作者： hang wang Quan-Feng He Yong Yang Department of Mechanical Engineering City University of Hong KongHong Kong 999077China Department of Materials Science and Engineering.City University of Hong Kong Hong Kong 999077China Department of Advanced Design and System Engineering.City University of Hong Kong Hong Kong 999077China

Conventional intermetallics are strong but ***,multi-principal element intermetallics,also termed as high-entropy intermetallics(HEIs)in the recent high-entropy alloy literature,are strong but malleable,some of which even show appreciable ductility and fracture toughness at room *** this article,we provide a focused review on the recent researches on HEIs,from the fundamentals,such as the concept of HEIs,the formation rules to the structural and functional properties of *** results hitherto reported clearly show that the HEIs with distinct properties could be a promising material for future structural and functional applications.

关键词： Internetallics High-entropy alloys Phase formation Mechanical properties Functional properies

Model prediction of the effect of in-mold electromagnetic stirring on negative segregation under bloom surface

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International Journal of Minerals,Metallurgy and Materials 2020年第3期27卷 319-327页

作者： Yu-kun Huo Li-hua Zhao hang-hang An Min wang Chang-dong Zou State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China National Engineering Research Center of Flat Rolling Equipment University of Science and Technology BeijingBeijing 100083China Institute of Research of Iron and Steel(IRIS)of Shasteel of Jiangsu Province Zhangjiagang 215625China

Aiming at the problem of negative segregation under a bloom surface, a coupling macrosegregation model considering electromagnetic field, flow, heat, and solute transport was established based on the volume average method to study the effect of in-mold electromagnetic stirring(M-EMS) on the negative segregation under the bloom surface. In the model, the influence of dendrite structure on the flow and solute transport was described by the change of permeability. The model was validated by the magnetic induction intensity of M-EMS and carbon segregation experiment. The results show that the solute C in the solidified shell in the turbulent zone of the bloom undergoes two negative segregations, whereby the first is caused by nozzle jet, and the second by the M-EMS. The severities of the negative segregation caused by M-EMS at different currents and frequencies are also different, and the larger the current is, or the smaller the frequency is, the more serious will be the negative *** the M-EMS, the solute C distribution in the liquid phase of the bloom is more uniform, but the mass fraction of C in the liquid phase is higher than that without M-EMS.

关键词： continuous casting in-mold electromagnetic stirring bloom negative segregation numerical simulation

Thermal transport mechanism of electrons and phonons in pristine and defective HfB_(2)

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Rare Metals 2023年第11期42卷 3651-3661页

作者： Ao wang Shou-hang Li Hua Bao Global Institute of Future Technology Shanghai Jiao Tong UniversityShanghai200240China University of Michigan-Shanghai Jiao Tong University Joint Institute Shanghai Jiao Tong UniversityShanghai200240China College of Mechanical Engineering Donghua UniversityShanghai201620China

Hafnium diboride(HfB_(2))is an important metallic ceramic that works in harsh environments,due to its high strength and thermal *** the thermal conductivity of HfB_(2) has been measured,the experimental results are ***,the thermal transport mechanism of HfB_(2) is not well *** this work,we study the thermal transport in both pristine and defective HfB_(2) from first-principles *** the pristine HfB_(2),the room-temperature thermal conductivities are 175.0 and 157.7 W·m^(-1)·K^(-1)on a-and c-axes,respectively,where the contributions from electron and phonon are *** Lorenz number is significantly smaller than the Sommerfeld value and shows a temperature dependence,which demonstrates that the Wiedemann-Franz law cannot be used to estimate electronic thermal *** phonon-isotope and the phonon-electron scattering are non-negligible compared to the phonon-phonon *** the defective HfB_(2),the grain size effects are negligible with length scales larger than 1μ*** pore can limit thermal conductivity when its occupancy is larger than 10%.The vacancy is found to induce scattered results in *** phonon thermal conductivity significantly reduces even with only 1%vacancy,while the electronic thermal conductivity is not sensitive to the *** study provides an in-depth understanding of the thermal transport in HfB_(2),and the revealed mechanisms provide important guidance on the design of HfB_(2)-based materials.

关键词： Thermal conductivity Electrical transport properties Boltzmann transport equation Vacancy scattering First-principles calculation

New groups of solutions to the Whitham-Broer-Kaup equation

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Applied Mathematics and Mechanics(English Edition) 2020年第11期41卷 1735-1746页

作者： Yaji wang hang XU Q.SUN State Key Lab of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Australian Research Council Centre of Excellence for Nanoscale BioPhotonics School of ScienceRMIT UniversityMelbourneVIC 3001Australia

The Whitham-Broer-Kaup model is widely used to study the tsunami *** classical Whitham-Broer-Kaup equations are re-investigated in detail by the generalized projective Riccati-equation method.20 sets of solutions are obtained of which,to the best of the authors’knowledge,some have not been reported in *** analysis of the planar dynamical systems is then used to show different phase portraits of the traveling wave solutions under various parametric conditions.

关键词： Whitham-Broer-Kaup equation travelling wave bifurcation analysis projective Riccati-equation method

Special topic on research frontiers in porous organic polymers

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Science China Chemistry 2017年第8期60卷 997-998页

作者： Bao-hang Han Dong wang National Center for Nanoscience and Technology Beijing 100190China Institute of Chemistry Chinese Academy of SciencesBeijing 100190China

Porous organic polymers(POPs)are materials with covalently bonded,thermally stable backbones that exhibit large accessible surface areas and intriguing properties applicable to fields such as gas storage and separation,catalysis,and *** to analogous inorganic porous materials,POPs feature a wider range of pore size,larger surface area,readily available functional groups for post-synthesis functionalization,etc.,which enables their design for targeted applications.

关键词：有机聚合物多孔材料持久性有机污染物专题 POPs 表面积热稳定官能团

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爆炸切割网络传爆中的间隙与角度效应

火工品 2025年第1期 37-43页

作者：周晓鹏姜勇袁航中国船舶集团有限公司第七一三研究所河南郑州450015 河南省水下智能装备重点实验室河南郑州450015

为研究爆炸切割网络中传爆节点处传爆能力的关键影响因素,通过改变切割索对传爆药柱的传爆间隙进行了平板传爆试验,将试验结果结合仿真分析确定了JO-11C传爆药柱的仿真材料参数,并进一步分析了传播角度对传爆能力的影响。研究结果表明:... 详细信息

为研究爆炸切割网络中传爆节点处传爆能力的关键影响因素,通过改变切割索对传爆药柱的传爆间隙进行了平板传爆试验,将试验结果结合仿真分析确定了JO-11C传爆药柱的仿真材料参数,并进一步分析了传播角度对传爆能力的影响。研究结果表明:随着传爆间隙的增加,传爆能力下降,切割索对传爆药柱的最大传爆间隙区间为2.0~2.5 mm;同时,传爆角度的增大能够显著提高传爆能力。本研究为爆炸切割网络的传爆性能研究以及提高武器系统的可靠性提供了参考。

关键词：爆炸切割网络传爆间隙传爆角度传爆药柱仿真分析

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不同冷却方式下高温混凝土的动态力学特性

爆炸与冲击 2025年第1期45卷 1-15页

作者：吴栩霆王振周航张国凯李硕标南京理工大学机械工程学院江苏南京210094

为了研究高温混凝土在不同冷却方式下的动态力学特性,通过φ74 mm大口径分离式霍普金森压杆对不同冷却方式处理下不同温度的C30圆柱形混凝土试样进行了动态力学性能试验,得到了其在热、水、力联合作用下的力学特性,探究了冷却方式、温... 详细信息

为了研究高温混凝土在不同冷却方式下的动态力学特性,通过φ74 mm大口径分离式霍普金森压杆对不同冷却方式处理下不同温度的C30圆柱形混凝土试样进行了动态力学性能试验,得到了其在热、水、力联合作用下的力学特性,探究了冷却方式、温度和加载条件对平均应变率的影响,重点分析了高温混凝土在不同方式冷却后的动态应力-应变曲线,以及冷却方式、温度和加载速率对其破碎形态、动态抗压强度、弹性模量、峰值应变及一系列动态效应的影响。结果表明:水冷混凝土试样的平均应变率受温度的影响更明显,不同冷却方式下加载速度与平均应变率近似呈线性关系;当温度达到400℃及以上时,试样颜色发生明显改变,相同温度下,水冷试样比自然冷却试样的颜色更深,出现更多细微裂纹,骨料形态破坏更严重;不同冷却方式下混凝土的动态抗压强度均与加载速度成正比,与加热温度成反比;水冷混凝土试样的弹性模量损伤系数低于自然冷却试样;高温混凝土试样的峰值应变与加热温度成正比,与加载速度成反比,且水冷混凝土试样的峰值应变相对值要高于自然冷却试样;混凝土的动载荷增加因子与温度及加载速度均成正比,且温度越高,混凝土的应变率效应越明显;当温度在200℃时,混凝土耗能系数出现反弹现象。

关键词：冷却方式冲击高温混凝土分离式霍普金森压杆动态力学特性破坏形态