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Probabilistic Response and Short-Term Extreme Load Estimation of Offshore Monopile Wind Turbine Towers by Probability Density Evolution Method

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China Ocean Engineering 2022年第3期36卷 363-371页

作者： ZHANG Hui XU ya-zhou School of Building Services Science and Engineering Xi’an University of Architecture and TechnologyXi’an 710055China School of Civil Engineering Xi’an University of Architecture and TechnologyXi’an 710055China

A new analysis framework based on probability density evolution method(PDEM)and its Chebyshev collocation solution are introduced to predict the dynamic response and short-term extreme load of offshore wind turbine(OWT)towers subjected to random sea *** regard to the stochastic responses,random function method is employed to generate samples of sea elevation,the probability density evolution equation(PDEE)is solved to calculate time-variant probability density functions of structural *** the probabilistic load estimation,a FAST model of NREL 5MW offshore turbine is established to obtain samples of bending moment at the tower *** equivalent extreme event theory is used to construct a virtual stochastic process(VSP)to assess the short-term extreme *** results indicate that the proposed approach can predict time-variant probability density functions of the structural responses,and shows good agreement with Monte Carlo ***,the predicted short-term extreme load can capture the fluctuation at the tail of the extreme value distribution,thus is more rational than results from the typical distribution ***,the proposed method shows good adaptation,precision and efficiency for the dynamic response analysis and load estimation of OWT towers.

关键词： offshore wind turbine probability density evolution method Chebyshev collocation matrix exponential Monte Carlo

Fabricating functionally graded Fe-Cr-Co permanent magnetic alloys via laser powder bed fusion

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Journal of Iron and Steel Research International 2024年第3期31卷 729-737页

作者： ya-zhou He ya-qing Hou Peng Shen Hao Zhang Dong zhou Hang Su Central Iron and Steel Research Institute Co. Ltd.Beijing 100081China Material Digital R&D Center China Iron and Steel Research Institute Group Co.Ltd.Beijing 100081China

Laser powder bed fusion(LPBF)in-situ alloying technology offers the possibility to construct gradient materials with varied structures and *** graded Fe-Cr-Co permanent magnetic alloys were fabricated by LPBF and in-situ alloying mixed powders of Fe,Cr,and Co *** effects of different Fe,Cr and Co contents on the microstructure,magnetic properties and hardness of Fe-Cr-Co alloys prepared by LPBF were *** as-built Fe-Cr-Co alloys present a single body-centered-cubic phase and have a homogeneous distribution of *** mechanical properties and magnetic properties of the compositionally graded sample show a gradient *** the increase in Cr content,the Vickers hardness of the sample increases,and the saturation magnetization of the sample *** optimal magnetic properties in an isotropic state are given as coercivity HcB=21.65 kA/m,remanence Br=0.70 T and energy product(BH)_(max)=5.35 kJ/m^(3),which are comparable to or higher than the reported magnetic properties in an isotropic state prepared by traditional powder *** in-situ alloying technology has the potential to further explore Fe-Cr-Co magnetic materials,such as those consisting of multiple or more constituent elements,and to maximize the compositional flexibility of magnetic materials.

关键词： Fe-Cr-Co alloy Laser powder bed fusion In-situ alloying Functional material Magnetic property

Water quality improvement of a lagoon containing mixed chemical industrial wastewater by micro-electrolysis-contact oxidization

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第5期12卷 390-398页

作者： ya-fei zhou Mao LIU Qiong wu College of Environmental Science and Engineering Nankai University Tianjin 300071 China The Eleventh Design & Research Institute of IT Co. Ltd Dalian Qffice Dalian 116600 China

A lagoon in the New Binhai District, a high-speed developing area, Tianjin, China, has long been receiving the mixed chemical industrial wastewater from a chemical industrial park. This lagoon contained complex hazardous substances such as heavy metals and accumulative pollutants which stayed over time with a poor biodegradability. According to the characteristics of wastewater in the lagoon, the micro-electrolysis process was applied to improve the biodegradability before the bioprocess treatment. By the orthogonal experimental study of main factors influencing the efficiency of the treatment method, the best control parameters were obtained, including pH=2.0, a volume ratio of Fe and reaction wastewater of 0.03750, a volume ratio of Fe and the granular activated carbon (GAC) of 2.0, a mixing speed of 200 r/min, and a hydraulic retention time (HRT) of 1.5 h. In the meantime, the removal rate of chemical oxygen demand (COD) was up to 64.6%, and NH4+-N and Pb in the influent were partly removed. After the micro-electrolysis process, the ratio of biochemical oxygen demand (BOD) to COD (B/C ratio) was greater than 0.6, thus providing a favorable basis for bioprocess treatment.

关键词： Memetic algorithm (MA) Neural network (NN) learning Back propagation (BP) Extremal optimization (EO) Levenberg-Marquardt (LM) gradient search Basic oxygen furnace (BOF)

Accumulation and elimination of iron oxide nanomaterials in zebrafish(Danio rerio) upon chronic aqueous exposure

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Journal of Environmental Sciences 2015年第4期27卷 223-230页

作者： yang Zhang Lin Zhu ya zhou Jimiao Chen Key Laboratory of Pollution Processes and Environmental Criteria Ministry of Education Tianjin Key Laboratory of Environmental Remediation and Pollution Control College of Environmental Science and Engineering Nankai University

A 52-day continuous semi-static waterborne exposure（test media renewed daily） regimen was employed to investigate the accumulation and elimination profiles of two iron oxide nanomaterials（nano-Fe2O3 and nano-Fe3O4） in zebrafish（Danio rerio）. Adult zebrafish were exposed to nanomaterial suspensions with initial concentrations of 4.0 and 10.0 mg/L for28 days and then were moved to clean water for 24 days to perform the elimination experiment. Fe content was measured in fish body and feces to provide data on accumulation and elimination of the two iron oxide nanomaterials in zebrafish. The experiment revealed that：（1） high accumulation of nano-Fe2O3 and nano-Fe3O4 were found in zebrafish, with maximum Fe contents, respectively, of 1.32 and 1.25 mg/g for 4.0 mg/L treatment groups and 1.15 and 0.90 mg/g for 10.0 mg/L treatment groups;（2） accumulated nanoparticles in zebrafish can be eliminated efficiently（the decrease of body burden of Fe conforms to a first-order decay equation） when fish were moved to nanoparticle-free water,and the elimination rates ranged from 86% to 100% by 24 days post-exposure; and（3）according to analysis of Fe content in fish excrement in the elimination phase, iron oxide nanomaterials may be adsorbed via the gastrointestinal tract, and stored for more than12 days.

关键词： Iron oxide nanomaterials Zebrafish Chronic exposure Accumulation Elimination

Theoretical and experimental study of surface texturing with laser machining

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Advances in Manufacturing 2021年第4期9卷 538-557页

作者： ya-zhou Mao Jian-Xi yang Jin-Chen Ji School of Mechatronics Engineering Henan University of Science and TechnologyLuoyang 471003HenanPeople’s Republic of China School of Mechanical and Mechatronic Engineering University of Technology SydneySydneyNSW 2007Australia

To explore the forming process and mechanism of the surface texture of laser micropits,this paper presents the thermal model of laser machining based on the Neumann boundary conditions and an investigation on the effects of various parameters on the *** surface profile and quality of the formed micropits were analyzed using NanoFocus 3D equipment through a design of experiment(DOE).The results showed that more intense melting and splashing occurred with higher power density and narrower pulse ***,the compressive stress is an important indicator of the damage effects,and the circumferential thermal stress is the primary factor influencing the diameter *** the process of laser machining,not only did oxides such as CuO and ZnO generate,the energy distribution also tended to decrease gradually from region#1 to region#3 based on an energy dispersive spectrometer(EDS)*** factors significantly affecting the surface quality of the micropit surface texture are the energy and pulse *** relationship between taper angle and energy is appropriately *** on the formation process and mechanism of the surface texture of laser micropits provides important guidance for precision machining.

关键词： Laser machining Thermal stress damage Surface texturing Design of experiment(DOE) Micropit

Calculation of Total Cross Section for Positron Scattering on Helium

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Chinese Physics Letters 1998年第3期15卷 180-182页

作者： zhou ya-jun PAN Shou-fu Institute of Atomic and Molecular Physics National Laboratory of Theoretical and Computational ChemistryJilin UniversityChangchun 130023

Total scattering cross sections for positron scattering on helium are calculated at intermediate energies and compared with experimental *** method used is the coupled-channels-optical method with an ab initio complex polarization potential,which takes all channels into *** results show that the ionization continuum and positronium formation rearrangment channels are very important parts in total scattering cross section of positron-helium collision.

关键词： positron collision method

Numerical design of an efficient Ho^(3+)-doped InF3 fiber laser at~3.2μm

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Journal of Electronic Science and Technology 2024年第3期22卷 35-46页

作者： Shi-Yuan zhou Hong-Yu Luo ya-zhou Wang Yong Liu State Key Laboratory of Electronic Thin Films and Integrated Devices School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu611731China DTU Electro Technical University of DenmarkKongens Lyngby2800Denmark

In this work,we theoretically unlock the potential of Ho^(3+)-doped InF3 fiber for efficient~3.2μm laser generation(from the ^(5)F_(4),^(5)S_(2)→^(5)F_(5) transition),by employing a novel dual-wavelength pumping scheme at 1150 nm and 980 nm,for the first *** clad-coupled 1150 nm pumping of 5 W,~3.2μm power of 3.6 W has been predicted with the optical-to-optical efficiency of 14.4%.Further efficient power scaling,however,is blocked by the output saturation with 980 nm *** alleviate this behavior,the cascaded ^(5)I_(5)→^(5)I_(6) transition,targeting~3.9μm,has been activated simultaneously,therefore accelerating the population circulation between the laser upper level ^(5)F_(4),^(5)S_(2) and long-lived ^(5)I_(6) level under 980 nm *** a result,enhanced~3.2μm power of 4.68 W has been obtained with optical-to-optical efficiency of 15.6%.Meanwhile the~3.9μm laser,yielding power of 2.76 W with optical-to-optical efficiency of 9.2%,is theoretically achievable as well with a moderate heat load,of which the performance is even better than the prior experimentally and theoretically reported Ho^(3+)-doped InF3 fiber lasers emitting at~3.9μm *** work demonstrates a versatile platform for laser generation at~3.2μm and~3.9μm,thus providing the new opportunities for many potential applications,e.g.,polymer processing,infrared countermeasures,and free-space communications.

关键词： Cascaded Fiber laser Holmium Mid-infrared

Positron Impact Ionization of Hydrogen, Sodium, and Potassium

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Chinese Physics Letters 1997年第5期14卷 348-351页

作者： zhou ya-jun PAN Shou-pu Institute of Atomic and Molecular Physics National Laboratory of Theoretical and Computational ChemistryJilin UniversityChangchun 130023

The total ionization cross sections for positron scattering by hydrogen,sodium,and potassium are calculated by applying an equivalent-local optical potential model from the ionization threshold to *** total ionization cross sections are in excellent agreement with the recent measurements of Jones et *** total ionization cross sections for sodium and potassium are compared with other theoretical calculations.

关键词： potassium ionization applying

Stability of the Phase Separation State for Compressible Navier-Stokes/Allen-Cahn System

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 45-74页

作者： ya-zhou Chen Hakho Hong Xiao-ding Shi Department of Mathematics College of Mathematics and PhysicsBeijing University of Chemical TechnologyBeijing100029China Institute of Mathematics State Academy of SciencesPyongyangKorea

This paper is concerned with the large time behavior of the Cauchy problem for Navier-Stokes/AllenCahn system describing the interface motion of immiscible two-phase flow in 3-D. The existence and uniqueness of global solutions and the stability of the phase separation state are proved under the small initial perturbations. Moreover, the optimal time decay rates are obtained for higher-order spatial derivatives of density,velocity and phase. Our results imply that if the immiscible two-phase flow is initially located near the phase separation state, then under small perturbation conditions, the solution exists globally and decays algebraically to the complete separation state of the two-phase flow, that is, there will be no interface fracture, vacuum, shock wave, mass concentration at any time, and the interface thickness tends to zero as the time t → +∞.

关键词： Navier-Stokes/Allen-Cahn system existence uniqueness large time behavior decay rate