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Efficient simulation of spatially correlated non-stationary ground motions by wavelet-packet algorithm and spectral representation method

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Earthquake Engineering and Engineering Vibration 2024年第4期23卷 799-814页

作者： ji Kun Cao Xuyang Wang Suyang wen Ruizhi College of Civil and Transportation Engineering Hohai UniversityNanjing 210098China The Key Laboratory of Urban Security and Disaster Engineering of ministry of Education Beijing University of TechnologyBeijing 100022China Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China

Although the classical spectral representation method(SRM)has been widely used in the generation of spatially varying ground motions,there are still challenges in efficient simulation of the non-stationary stochastic vector process in *** first problem is the inherent limitation and inflexibility of the deterministic time/frequency modulation *** difficulty is the estimation of evolutionary power spectral density(EPSD)with quite a few *** tackle these problems,the wavelet packet transform(WPT)algorithm is utilized to build a time-varying spectrum of seed recording which describes the energy distribution in the time-frequency *** time-varying spectrum is proven to preserve the time and frequency marginal property as theoretical EPSD will do for the stationary *** the simulation of spatially varying ground motions,the auto-EPSD for all locations is directly estimated using the time-varying spectrum of seed recording rather than matching predefined EPSD *** the constructed spectral matrix is incorporated in SRM to simulate spatially varying non-stationary ground motions using efficient Cholesky decomposition *** addition to a good match with the target coherency model,two numerical examples indicate that the generated time histories retain the physical properties of the prescribed seed recording,including waveform,temporal/spectral non-stationarity,normalized energy buildup,and significant duration.

关键词： non-stationarity time-varying spectrum wavelet packet transform(WPT) spectral representation method(SRM) response spectrum spatially varying recordings

Composition Operators on α-Bloch Spaces of the Unit Ball

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Acta Mathematica Sinica,English Series 2007年第11期23卷 1991-2002页

作者： min Zhu ZHANG wen XU Department of Mathematics Nanjing Normal University Nanjing 210097 P. R. China Department of Mathematics Southeast University Nanjing 210096 P. R. China Department of Physics and Mathematics University of Joensuu Fin-80101 Joensuu Finland

The authors characterize the boundedness and compactness of composition operators between α-Bloch spaces of the unit ball.

关键词： α-Bloch space composition operator boundedness compactness

A passive current sensor employing self-biased magnetoelectric transducer and high-permeability nanocrystalline flux concentrator

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Rare Metals 2022年第7期41卷 2343-2348页

作者： ji-Tao Zhang Yu-Mei wen Ping Li Research Center of Sensors and Instruments College of Optoelectronic EngineeringChongqing UniversityChongqing 400044China Department of Smart Grids and Information Engineering College of Electric and Information EngineeringZhengzhou University of Light IndustryZhengzhou 450002China

A passive current sensor,consisting of SmFe_(2)/PZT/SmFe_(2)self-biased magnetoelectric(ME)composite and Fe_(73.5)Cu_(1)Nb_(3)Si_(13.5)B_(9)nanocrystalline flux concentrator for weak current detection at power-line frequency,was fabricated and *** magnetostrictive material of SmFe_(2)plate with large anisotropic constant provides a huge internal anisotropic field to bias the ME transducer in closed magnetic ***,the additional magnetomotive force induced by the internal field and the corresponding increased effective permeabil-ity contribute to the improvement of the *** results demonstrate that the presented sensor has a higher sensitivity of 152 mV·A^(-1)at 50 Hz with a slight nonlinearity of~0.01%full scale(FS)and matches well with the predicted *** presented current-sensing device exhibits approximately 2.3 times higher sensitivity than that of conventional ME composite with[Pb(Zr_(0.48),Ti_(0.52)O_(3)](PZT)and Terfenol-D plates serving as a key sensitive *** addition,time stabilities of the presented sensor were evaluated for a long period of 72 h and analyzed through mathematical statistics method,and favorable stabilities with an uncertainty of 0.5μV are obtained in continuous 1 h *** results provide a significant advancement toward promising application of the tri-layer self-biased ME laminate for power-line elec-tric cords monitoring.

关键词： Magnetoelectric effects Current sensor Magnetic flux concentrator Magnetostrictive rare earth iron alloys

Compound Product of Hypermatrices

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Journal of Systems Science & Complexity 2024年第1期37卷 169-183页

作者： CHENG Daizhan MENG min ZHANG Xiao ji Zhengping Key Laboratory of Systems and Control Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China Department of Control Science and Engineering School of Electronics and Information EngineeringTongji UniversityShanghai 201210China National Center for Mathematics and Interdisciplinary Sciences Chinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100149China.

The semi-tensor product(STP)of matrices is generalized to multidimensional arrays,called the compound product of *** product is first defined for three-dimensional hypermatrices with compatible orders and then extended to general *** different types of hyperdeterminants are introduced and certain properties are *** Lie groups and Lie algebras corresponding to the hypermatrix products are ***,these results are applied to dynamical systems.

关键词： Compound semi-tensor product hyperdeterminants hypereigenvalues and hypereigenvectors hypergeneral linear groups hypermatrices.

FCC DeSO_x and DeNO_x additive technology

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Journal of Environmental Sciences 2000年第3期12卷 310-318页

作者： wen Bin HE min-yuan Research Institute of Petroleum Processing SINOPECBeijing 100083China.

The fluid catalytic cracking(FCC) is the principal gasoline producing process in the refinery. Considerable amounts of harmful sulfur oxides and nitrogen oxides (SO x and NO x) are generated with the FCC operation. Impacted by strengthening environmental regulations and the current global emphasis on environmental protection and pollution abatement, refiners have been meaning to look for effective ways to control and reduce SO x and NO x emissions. FCC DeSO x and DeNO x additives is the most promising measure. The present paper reviews the developments in FCC DeSO x and DeNO x additive technology based on the respective authors' works, the future directions of the technology are also discussed.

关键词： FCC DeSO_x SO_x DeSO_x additive DeNO_x additive

Insight into the formation mechanism of levoglucosenone in phosphoric acid-catalyzed fast pyrolysis of cellulose

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Journal of Energy Chemistry 2020年第4期29卷 78-89页

作者： Bin Hu Qiang Lu Yu-ting Wu wen-luan Xie min-shu Cui ji Liu Chang-qing Dong Yong-ping Yang National Engineering Laboratory for Biomass Power Generation Equipment North China Electric Power UniversityBeijing 102206China

The catalytic fast pyrolysis of cellulose impregnated with phosphoric acid (H3PO4) offers a promising method for the selective production of levoglucosenone (LGO),a valuable anhydrosugar ***,the fundamental mechanism for selective LGO formation is ***,quantum chemistry calculations and catalytic fast pyrolysis experiments were performed to reveal the formation mechanism of LGO in H3PO4-catalyzed cellulose pyrolysis.H3PO4 significantly decreased the energy barriers of the pyrolytic reactions and altered the competitiveness of the LGO formation pathways,promoting LGO *** different pathways in the non-catalytic and H3P04-catalyzed conditions,LGO is mainly produced from the primary decomposition of glucose units of cellulose and secondary conversion of *** major catalytic formation pathways of LGO comprise similar reactions,with dehydration at the 3-OH+2-H site as the rate-determining ***,secondary conversion of 1,4;3,6-dianhydro-α-D-glucopyranose is not feasible for LGO formation,in contrast to previous *** addition,a high degree of polymerization is beneficial for the selectivity of LGO formation in the catalytic process,because the glycosidic bond is important for the formation of the bicyclic structure (1,5-and1,6-acetal rings).

关键词： Phosphoric acid Levoglucosenone Formation mechanism Density functional theory Py-GC/MS

Impact of photoneutrons on reactivity measurements for TMSR-SF1

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Nuclear Science and Techniques 2017年第6期28卷 101-107页

作者： Rui-min ji ming-Hai Li Yang Zou Gui-min Liu Shanghai Institute of Applied Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

The solid-fueled thorium molten salt reactor(TMSR-SF1) is a 10 MW_(th) test reactor design to be deployed in 5-10 years by the TMSR *** design combines coated particle fuel and molten FLiBe coolant for great intrinsic safety features and economic *** to a large amount of beryllium in the coolant salt,photoneutrons are produced by(y,n) reaction,hence the increasing fraction of effective delayed neutrons in the core by the photoneutrons originating from the long-lived fission *** of the delayed photoneutron groups are of long lifetime,so a direct effect is resulted in the transient process and reactivity *** study the impact of photoneutrons for TMSR-SF1,the effective photoneutron fraction is estimated using k-ratio method and performed by the Monte Carlo code(MCNP5) with ENDF/B-Ⅶ cross *** on the coupled neutronphoton point kinetics equations,influence of the photoneutrons is *** results show that the impact of photoneutrons is not negligible in reactivity *** considering photoneutrons in on-line reactivity measurement based on inverse point kinetics can result in overestimation of the positive reactivity and underestimation of the negative *** photoneutrons also lead to more waiting time for the doubling time *** the photoneutron precursors take extremely long time to achieve equilibrium,a "steady" power operation may not directly imply a "real" criticality.

关键词： TMSR-SF1 Delayed photoneutrons Coupled neutron-photon point kinetics Reactivity measurement

Wall-Attached Night Ventilation Combined with Phase Change Material Wallboard in Hot Summer:An Experimental Study on the Thermal Performance

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Journal of Thermal Science 2022年第2期31卷 318-331页

作者： ji wenhui YUAN Yanping LI Yajun YU min School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

Night ventilation is regarded as a promising cooling strategy by storing night cooling in the thermal mass of the ***,night ventilation performance in hot summer is restricted by the climatic *** this paper,we propose a new solution as the integration of wall-attached night ventilation(WANV)and phase change material wallboard(PCMW).The principle of the proposed system is to utilize the wall-attached jet ventilation to achieve forced convection and to adopt latent energy storage of PCMW to enlarge the energy storage density capabilities,and the coupling method is expected to improve the night ventilation *** experiments were conducted to evaluate the thermal performance of the hybrid system by evaluating indoor temperature history,thermal comfort time and cooling *** to the high thermal energy storage density capability of PCMW,it was found that the presence of PCMW has a negative influence on night cooling efficiency but still has a positive influence on the overall cooling *** proposed WANV combined with the PCMW system significantly increased the temperature decrease of room air and west wall inside surface during one hour's night ventilation by 94.97%and 67.74%,respectively,and reached an extension of 38.42%of indoor thermal comfort *** results highlight the potential of WANV integration of PCMW to improve the thermal performance of night ventilation.

关键词： night ventilation wall-attached jet ventilation phase change material wallboard thermal performance

General Solutions of Matrix Extension Associated with Multiple Channel Biorthogonal Wavelet Filters

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Acta Mathematica Sinica,English Series 2007年第7期23卷 1241-1250页

作者： wen Bin WEI min HUANG Department 4 Air Force Radar Academy Institute of Mathematics.Chinese Academu of Sciences

This paper is concerned with seeking the general solutions of matrix equation M（ξ）M＊（ξ） = Is for the construction of multiple channel biorthogonal wavelets, provided that some special solution of its is known.

关键词： matrix extension refinement equation biorthogonal wavelet