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On Estimating Regression Coefficients in Seemingly Unrelated Regression System

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Acta Mathematicae Applicatae Sinica 2015年第4期31卷 935-944页

作者： Li-chun wang Department of Mathematics Beijing Jiaotong University

In the system of m （m ≥ 2） seemingly unrelated regressions, we show that the Gauss-Markov estimator （GME） of any regression coefficients has unique simplified form, which exactly equals to the one- step covariance-adjusted estimator of the regression coefficients, and hence we conclude that for any finite k ≥ 2 the k-step covariance-adjusted estimator degenerates to the one-step covariance-adjusted estimator and the corresponding two-stage Aitken estimator has exactly one simplified form. Also, the unique simplified expression of the GME is just the estimator presented in the Theorem 1 of wang＇ work [1988]. A new estimate of regression coefficients in seemingly unrelated regression system, Science in China, Series A 10, 1033-1040].

关键词： seemingly unrelated regressions Causs-Markov estimator simplified form covariance-adjustedmethod

Constructing BaTiO_(3)/TiO_(2)@polypyrrole composites with hollow multishelled structure for enhanced electromagnetic wave absorbing properties

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International Journal of Minerals,Metallurgy and Materials 2023年第3期30卷 581-590页

作者： Dan Mao Zhen Zhang Mei Yang Zumin wang Ranbo Yu Dan wang State Key Laboratory of Biochemical Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China Department of Energy Storage Science and Engineering School of Metallurgical and Ecological EngineeringUniversity of Science and Technology BeijingBeijing 100083China University of Chinese Academy of Sciences Beijing 100049China

BaTiO_(3)/TiO_(2)@polypyrrole(PPy)composites with hollow multishelled structure(HoMS)were constructed to enhance the electromagnetic wave absorbing properties of BaTiO_(3)-based absorbing ***_(3)/TiO_(2)HoMSs were prepared by hydrothermal crystallization using TiO_(2)Ho MSs as ***,FeCl3 was introduced to initiate the oxidative polymerization of pyrrole monomer,forming BaTiO_(3)/TiO_(2)@PPy HoMSs *** electromagnetic wave absorbing properties of BaTiO_(3)/TiO_(2)HoMSs and BaTiO_(3)/TiO_(2)@PPy Ho MSs with different shell number were investigated using a vector network *** results indicate that BaTiO_(3)/TiO_(2)@PPy HoMSs exhibit improved microwave absorption compared with BaTiO_(3)/TiO_(2)*** particular,tripled-shelled BaTiO_(3)/TiO_(2)@PPy HoMS has the most excellent absorbing *** best reflection loss can reach up to-21.80 dB at 13.34 GHz with a corresponding absorber thickness of only 1.3 mm,and the qualified absorption bandwidth of tripled-shelled BaTiO_(3)/TiO_(2)@PPy HoMS is up to 4.2 *** work paves a new way for the development of high-performance composite microwave absorbing materials.

关键词： BaTiO_(3)/TiO_(2)@polypyrrole composites hollow multishelled structure electromagnetic wave absorbing

Comparison of Temperature Field Distribution between Cement Preclinkering Technology and Cement Precalcining Technology

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Journal of Wuhan University of Technology(Materials Science) 2016年第2期31卷 355-360页

作者：徐迅 wang Lan Country State Key Laboratory of Green Building Materials China Building Materials Academy Beijing 100024 China Country State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials Southwest University of Science and Technology Mianyang 62101O China

Through the comparison of calcination conditions between cement preclinkering technology and cement precalcining technology,we studied the characteristics of temperature field distribution of cement preclinkering technology systems including cyclone preheater,preclinkering furnace,and rotary *** used numericalsimulation method to obtain data of temperature field *** results are found by system *** ratio of tailcoalof cement preclinkering technology is about 70%,and raw mealtemperature can reach 1070 ℃.Shorter L/D kiln type of preclinkering technology can obtain more stable calcining zone *** highest solid temperature of cement preclinkering technology is higher than 80 ℃,and high temperature region（〉1450 ℃）length is 2 times,which is beneficialfor calcining clinker and higher clinker *** cement preclinkering technology can obtain more performance temperature filed,which improves both the solid-phase reaction and liquid-phase reaction.

关键词： cement preclinkering technology temperature field distribution kiln production heat balance solve the equation

Metal-organic framework-derive d carbon-base d composites for electromagnetic wave absorption:Dimension design and morphology regulation

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Journal of Materials Science & Technology 2023年第1期132卷 223-251页

作者： Yujie Ren Xin wang Jiaxin Ma Qi Zheng Lianjun wang Wan Jiang State Key Laboratory for Modification of Chemical Fibers and Polymer Materials and College of Materials Science and Engineering Donghua UniversityShanghai 201620China Institute of Functional Materials Donghua UniversityShanghai 201620China Engineering Research Center of Advanced Glasses Manufacturing Technology Ministry of EducationDonghua UniversityShanghai 201620China

Developing highly efficient microwave absorbing materials(MAMs)to ameliorate the electromagnetic(EM)response and facilitate energy absorption is crucial in both the civil and military ***-organic framework(MOF)derived nanoporous carbon composites have emerged as advanced MAMs ow-ing to their rich porosity,tunable compositions,facile functionalization,and morphology ***-gether with the flourishing development of composition-tuning strategy,the rational dimension design and elaborate control over the architectures have also evolved into an effective approach to regulating their EM ***,we provide a comprehensive review of the recent advances in using di-mension and morphology modulation to adjust the microwave attenuation capacities for MOF-derived carbon *** underlying design rules and unique advantages for the MAMs of various dimen-sions were discussed with the selection of representative work,providing general concepts and insight on how to efficiently tune the ***,the fundamental dimension-morphology-function relationship was also ***,the challenges and perspectives of dimension design and mor-phology control over MOF-derived MAMs were also presented.

关键词： MOF-derived carbon composites Electromagnetic microwave absorption Dimension design Morphology regulation

Study of white-light flares observed by Hinode

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Chinese Journal of Astronomy and Astrophysics 2009年第2期9卷 127-132页

作者： Hai-Min wang Space Weather Research Lab Center for Solar Terrestrial Research New Jersey Institute of Technology Newark NJ 07102 USA

White-light flares are considered to be the most energetic flaring events that are observable in the optical broad-band continuum of the solar spectrum. They have not been commonly observed. Observations of white-light flares with sub-arcsecond resolution have been very rare. The continuous high resolution observations of Hinode provide a unique opportunity to systematically study the white-light flares with a spatial resolution around 0.2 arcsec. We surveyed all the flares above GOES magnitude C5.0 since the launch of Hinode in 2006 October. 13 of these kinds of flares were covered by the Hinode G-band observations. We analyzed the peak contrasts and equivalent areas （calculated via integrated excess emission contrast） of these flares as a function of the GOES X-ray flux, and found that the cut-off visibility is likely around M1 flares under the observing limit of Hinode. Many other observational and physical factors should affect the visibility of white-light flares; as the observing conditions are improved, smaller flares are likely to have detectable white-light emissions. We are cautious that this limiting visibility is an overestimate, because G-band observations contain emissions from the upper atmosphere. Among the 13 events analyzed, only the M8.7 flare of 2007 June 4 had near-simultaneous observations in both the G-band and the blue continuum. The blue continuum had a peak contrast of 94% vs. 175% in G-band for this event. The equivalent area in the blue continuum is an order of magnitude lower than that in the G-band. Very recently, Jess et al. studied a C2.0 flare with a peak contrast of 300% in the blue continuum. Compared to the events presented in this letter, that event is probably an unusual white-light flare： a very small kernel with a large contrast that can be detected in high resolution observations.

关键词： Sun activity - Sun flares - Sun magnetic fields

Design,Hydrodynamic Analysis,and Testing of a Bio-inspired Movable Bow Mechanism for the Hybrid-driven Underwater Glider

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Journal of Bionic Engineering 2023年第4期20卷 1493-1513页

作者： Yanhui wang Yudong Guo Shaoqiong Yang Tongshuai Sun Xi wang Huihui Zhou Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education Tianjin UniversityTianjin300072China The Joint Laboratory of Ocean Observing and Detection Laoshan LaboratoryQingdao266237China

Hybrid-driven Underwater Glider(HUG)is a new type of underwater vehicle which integrates the functions of an Autonomous Underwater Glider(AUG)and an Autonomous Unmanned Vehicle(AUV).Although HUG has the characteristics of long endurance distance,its maneuverability still has room to be *** work introduces a new movement form of the neck of the underwater creature into HUG and proposes a parallel mechanism to adjust the attitude angle and displacement of the HUG’s bow,which can improve the steering ***,the influence of bow movement and rotation on the hydrodynamic force and flow field of the whole machine is analyzed by using the Computational Fluid Dynamics(CFD)*** degree of freedom,attitude control range and movement amount of the Movable Bow Mechanism(MBM)are obtained,and then the design of MBM is completed based on these ***,the kinematic and dynamic models of MBM are established based on the closed vector method and the Lagrange equation,respectively,which are fully verified by comparing the results of simulation in Matlab and Adams software,then a Radial Basis Function(RBF)neural network adaptive sliding mode controller is designed to improve the dynamic response effect of the output parameters of ***,a prototype of MBM is manufactured and *** kinematic,dynamics model and controller are verified by experiments,which provides a basis for applying MBM in HUGs.

关键词： Underwater glider Movable bow mechanism Hydrodynamic simulation Steering maneuverability

Ferrocene-induced switchable preparation of metal-nonmetal codoped tungsten nitride and carbide nanoarrays for electrocatalytic HER in alkaline and acid media

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Nano Research 2023年第2期16卷 2085-2093页

作者： Jian Zhou Fanfan wang Haiqing wang Shuxian Hu Weijia Zhou Hong Liu Institute for Advanced Interdisciplinary Research(iAIR) School of Chemistry and Chemical EngineeringUniversity of JinanJinan 250022China Department of Physics University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China

Transition metal nitride/carbide(TMN/C)have been actively explored as low-cost hydrogen evolution reaction(HER)electrocatalysts owing to their Pt-like physical and chemical ***,pure TMN/C suffers from strong hydrogen adsorption and lacks active centers for water ***,we developed a switchable WO_(3)-based in situ gas–solid reaction for preparing sophisticated Fe-N doped WC and Fe-C doped WN ***,the switch of codoping and phase can be effectively manipulated by regulating the amount of *** Fe-C-WN and Fe-N-WC exhibit robust electrocatalytic performance for HER in alkaline and acid electrolytes,*** collective collaboration of morphological,phase and electronic effects are suggested to be responsible for the superior HER *** smallest|ΔGH*|value of Fe-NWC indicates preferable hydrogen-evolving kinetics on the Fe-N-WC surface for HER under acid condition,while Fe-C-WN is suggested to be beneficial to the adsorption and dissociation of H_(2)O for HER in alkaline electrolyte.

关键词： gas–solid reaction tungsten nitride/carbide codoping phase regulation hydrogen evolution

Operation-area-constrained Adaptive Primary Frequency Support Strategy for Electric Vehicle Clusters

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Journal of Modern Power Systems and Clean Energy 2023年第6期11卷 1982-1994页

作者： Tianqi Liu Pengyu wang Qiao Peng Min Zhang Tengxin wang Jinhao Meng College of Electrical Engineering Sichuan UniversityChengdu 610065China Electric Power Research Institute State Grid Shanxi Electric Power CompanyTaiyuan 030001China

Due to their fast response and strong short-term power throughput capacity, electric vehicles(EVs) are promising for providing primary frequency support to power grids. However, due to the complicated charging demands of drivers, it is challenging to efficiently utilize the regulation capacity of EV clusters for providing stable primary frequency support to the power grid. Accordingly, this paper proposes an adaptive primary frequency support strategy for EV clusters constrained by the charging-behavior-defined operation area. First, the forced charging boundary of the EV is determined according to the driver's charging behavior, and based on this, the operation area is defined. This ensures full utilization of the available frequency support capacity of the EV. An adaptive primary frequency support strategy of EV clusters is then proposed. The output power of EV is adaptively regulated according to the real-time distance from the EV operating point to the forced charging boundary. With the proposed strategy, when the EV approaches the forced charging boundary, its output power is gradually reduced to zero. Then, the rapid state-of-charge declines of EVs and sudden output power reductions in EV clusters caused by forced charging to meet the driver's charging demands can be effectively avoided. EV clusters can then provide sustainable frequency support to the power grid without violating the driver's charging demands. Simulation results validate the proposed operation-area-constrained adaptive primary frequency support strategy, which outperforms the average strategy in terms of stable output maintenance and the optimal utilization of regulation capacities of EV clusters.

关键词： Primary frequency control frequency support electric vehicle vehicle-to-grid(V2G) operation area charging behavior

Application of nanozymes in problematic biofilm control:progress,challenges and prospects

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Frontiers of Environmental Science & Engineering 2024年第11期18卷 65-84页

作者： Junzheng Zhang Tong Dou Yun Shen Wenrui wang Luokai wang Xuanhao Wu Meng Zhang Dongsheng wang Pingfeng Yu College of Environmental and Resource Sciences Zhejiang UniversityHangzhou 310058China Innovation Center of Yangtze River Delta Zhejiang UniversityJiashan 314100China Department of Civil and Environmental Engineering The George Washington UniversityWashingtonDC 20052USA

Current microbial control strategies face challenges in keeping up with the escalation of microbial problems due to the presence of ***,there is an urgent need to develop effective and robust strategies to control problematic biofilms in water treatment and reuse ***,which have intrinsic biocatalytic activity and broad antibacterial spectra,hold promise for controlling resilient *** review summarizes the milestones of nanozyme studies and their applications as antibiofilm *** mechanisms behind the antibacterial,quorum quenching,and depolymerizing properties of nanozymes with different enzyme activities are ***,the surface and composition of nanozymes are crucial for their efficacy in biofilm control;thus,rationally designed nanozymes can increase their ***,the challenges of nanozymes as antibiofilm agents in realistic scenarios are investigated along with proposed strategies to overcome these *** of nanozyme-based biofilm control,such as machine learning-assisted nanozyme design,are also ***,this review highlights the potential of nanozymes as antibiofilm agents and provides insights into the future design of nanozymes for biofilm control.

关键词： Nanozymes Biofilm Antibacterial mechanisms Rational design Machine learning