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Two-decadal shifts in phytoplankton functional taxa (2002–2022) in response to extreme marine heatwaves

Optics Express 2025年第10期33卷 21961-21978页

作者： Ronglong Chen Deyong Sun Shengqiang Wang Yongjun Jia Muhammad Bilal Shuyan Lang Zhenghao Li State Key Laboratory of Climate System Prediction and Risk Management Nanjing University of Information Science and Technology Nanjing 210044 China School of Marine Sciences Nanjing University of Information Science and Technology Nanjing 210044 China Key Laboratory of Space Ocean Remote Sensing and Application Ministry of Natural Resources Beijing 100081 China National Satellite Ocean Application Service Beijing 100081 China Architecture and City Design Department College of Design and Built Environment King Fahd University of Petroleum and Minerals (KFUPM) Dhahran 31261 Saudi Arabia Interdisciplinary Research Center for Aviation & Space Exploration (IRC-ASE) King Fahd University of Petroleum and Minerals (KFUPM) Dhahran 31261 Saudi Arabia

Phytoplankton play a crucial role in the primary productivity of ocean ecosystems, rendering changes in their populations particularly consequential. The effects of extreme sea surface temperature (SST) on phytoplankton are noteworthy. However, the direct characterization of total biomass by chlorophyll for analysis is inaccurate for phytoplankton functional taxa (PFTs) with different sensitivity to SST. Through the method of Diagnostic pigment analysis (DPA), these organisms can be classified into six primary functional taxa based on their distinctive pigments, which play a vital role in elucidating their ecological functions and dynamics. This study employed optical remote sensing to reconstruct daily concentrations and occupancy of six PFTs in the Eastern China Marginal Sea (ECMS) over the past 20 years. Causal analyses were conducted to identify regions with varying sensitivity to SST changes and further explore the corresponding impacts on phytoplankton concentrations. Results revealed that high-causality areas in the Bohai Sea (BS) and Yellow Sea (YS) were primarily located in nearshore waters. In contrast, high-causality regions in the East China Sea (ECS) were farther offshore, while nearshore areas exhibited lower causality. The high-causality subregions experienced significant fluctuations in phytoplankton concentrations, particularly during marine heatwave (MHW) events, with a prevailing trend of decline in taxon concentrations driven by elevated SST. In comparison, low-causality subregions displayed weaker synchronization with SST changes, as other factors influenced taxa concentrations more prominently. Notably, while phytoplankton concentrations fluctuated significantly during extreme MHW events, they eventually reverted to baseline levels. However, with the increasing frequency and intensity of MHWs due to global warming, the capacity for phytoplankton to recover under such repeated stress remains uncertain. This study emphasizes the necessity of furt

关键词： Absorption coefficient Optical absorption Optical properties Remote sensing Spatial resolution Strain

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Experimental study on the sub-channel void fraction characteristics of bubbly flow in rod bundles

Experimental study on the sub-channel void fraction characte...

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2020 International Conference on Nuclear Engineering, ICONE 2020, collocated with the ASME 2020 Power Conference

作者： Ren, Quan-Yao Pu, Zeng-Ping Zheng, Mei-Yin Su, Min Chen, Ping Pan, Liang-Ming He, Hui He, Qing-Che Science and Technology on Reactor System Design Technology Laboratory Chengdu China Chongqing China

ISBN: (纸本)9780791883785

The gas-liquid two-phase flow behaviors are always associated with its dynamic void fraction, such as flow resistance, heat transfer coefficient, phase distribution, critical heat flux etc. As regard to the commercial PWR and BWR, rod bundles are the typical geometry, which contains many subchannels for coolant flowing. In present study, the sub-channel void fraction was measured in 5×5 rod bundles with the subchannel impedance void meter consisting of 12 strip electrodes. Based on the measured void fraction in different sub-channels, the void fraction dynamics, PDF (probability distribution function) and CDF (cumulative distribution function) curves were analyzed to make clear the effect of superficial gas and liquid velocity, flow development and casing tube. The empirical correlation for PDF of dynamic sub-channel void fraction has been developed, which showed good fitness with PDF and CDF curves and satisfying accuracy of averaged void fraction. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Void fraction

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Analysis of RCS depressurization effects on containment temperature for Qinshan phase II nuclear power plant 22

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2014 22nd International Conference on Nuclear Engineering, ICONE 2014

作者： Lili, Liu Ming, Zhang Jian, Deng Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Chengdu China

ISBN: (纸本)9780791845936

A severe accident code was applied for modeling of a typical pressurized water reactor (PWR) nuclear power plant, and the effects of RCS depressurization on the gas temperature of the relief tank cell in the containment during a station blackout (SBO) induced accident was analyzed. The sensitivity calculation indicated that the hydrogen generation rate obviously increased due to RCS depressurization in a critical stage. The results show that RCS depressurization can play an important role in hydrogen generation rate and total accumulation, and the temperature of the containment atmosphere is highly influenced by hydrogen combustion. High temperature induced by hydrogen combustion may degrade the equipment and instruments capabilities. Based on this analysis, a feasible strategy of RCS depressurization for mitigating the accident consequence is provided for developing the capacity of the SBO treatment of Qinshan Phase II Nuclear Power Plant (QSP-II NPP). Copyright © 2014 by ASME.

关键词： Nuclear power plants

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Theoretical research on two-phase flow instability in parallel rectangular channels under periodic perturbation

Theoretical research on two-phase flow instability in parall...

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2020 International Conference on Nuclear Engineering, ICONE 2020, collocated with the ASME 2020 Power Conference

作者： Qian, Libo Deng, Jian Huang, Tao Cai, Rong Science and Technology on Reactor System Design Technology Laboratory Npic Chengdu Sichuan China

ISBN: (纸本)9780791883785

A theoretical model for Density Wave Oscillations (DWOs) flow instability in parallel rectangular channels under periodic heaving motion is established with a lumped mathematical model based on homogenous hypothesis. The parallel rectangular channels comprise of the entrance section, the heating section, the riser section and the upper- and lower plenums, which guarantee the isobaric pressure drop condition between channels and the model consists of boiling channel model, pressure drop model, parallel channel model, additional pressure drop model generated by heaving motions, the constitutive and numerical models. The effect of periodic perturbation is introduced through additional pressure drop in the momentum equation. The model is validated with experimental data of a twin-rectangular-channel flow instability experiment under static condition. Then the flow instability in parallel-rectangular-channel system is studied under periodic perturbation and the margin of flow instability and the threshold power of the system under static condition is calculated as basis condition for comparison. The effect of the amplitude and period of perturbation is analyzed analytically and the results show that the amplitude and period of perturbation shows little effect on flow instability. While when the additional pressure difference introduced by heaving motion is comparable with that under static condition, the effect of amplitude becomes stronger. And the period of perturbation strongly effects the threshold power when it is identical to that of natural period of the system, which can be explained by resonance between the perturbation and the system. And this effect is even stronger when the asymmetric heating condition is introduced. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Pressure drop

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Study on material selection of reactor pressure vessel of SCWR

Study on material selection of reactor pressure vessel of SC...

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Energy Materials 2014

作者： Shuli, Ma Ying, Luo Qinwei, Yin Changxiang, Li Guofu, Xie Science and Technology on Reactor System Design Technology Laboratory NPIC Chengdu610041 China

ISBN: (纸本)9781119027942

This paper first analyzes the feasibility of SA-508 Grade 3 Class 1 Steel as an alternative material for Supercritical Water-Cooled reactor (SCWR) reactor Pressure Vessel (RPV). This kind of steel is limited to be applied in SCWR RPV due to its quenching property, though large forging could be accomplished by domestic manufacturers in forging aspect. Therefore, steels with higher strength and better quenching property are needed for SWCR RPV. The chemical component of SA-508 Gr.3 Cl.2 steel is similar to that of SA-508 Gr.3 Cl.1 steel, and more appropriate matching of strength and toughness could be achieved by the adjusting the elements contents, as well as proper control of tempering temperature and time. In light of the fact that Cl.2 steel has been successfully applied to steam generator, it could be an alternative material for SWCR RPV. SA-508 Gr.4N steel with high strength and good toughness is another alternative material for SCWR RPV. But large amount of research work before application is still needed for the lack of data on welding and irradiation etc.

关键词： Water cooled reactors

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Modeling of Mesoscale Creep Behaviors and Macroscale Creep Responses of Composite Fuels Under Irradiation Conditions

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Acta Mechanica Solida Sinica 2022年第6期35卷 1040-1054页

作者： Jing Zhang Jingyu Zhang Haoyu Wang Changbing Tang Pan Yuan Chunyu Yin Shurong Ding Yuanming Li Institute of Mechanics and Computational Engineering Department of Aeronautics and AstronauticsFudan UniversityShanghai200433China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu610213China

A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale creep responses,excluding the contributions of volumetric strain induced by the irradiation swelling deformations of fuel particles.A finite element(FE)modeling method for uniaxial tensile creep tests is established with the irradiation effects of nuclear materials taken into *** proposed models and simulation strategy are numerically implemented to a kind of composite nuclear fuel,and the predicted mesoscale creep behaviors and the macroscale creep responses are *** research results indicate that:(1)the macroscale creep responses and the mesoscale stress and strain fields are all greatly affected by the irradiation swelling of fuel particles,owing to the strengthened mechanical interactions between the fuel particles and the matrix.(2)The effective creep rates for a certain case are approximately two constants before and after the critical fission density,which results from the accelerated fission gas swelling after fuel grain recrystallization,and the effects of macroscale tensile stress will be more enhanced at higher temperatures.(3)The macroscale creep contributions from the fuel particles and matrix depend mainly on the current volume fractions varying with fission density.(4)As a function of the macroscale stress,temperature,initial particle volume fraction and particle fission rate,a multi-variable mathematical model for effective creep rates is fitted out for the considered composite fuels,which matches well with the FE *** study supplies important theoretical models and research methods for the multi-scale creep behaviors of various composite fuels and provides a basis for simulation of the thermal–mechanical behavior in related composite fuel elements and assemblies.

关键词： Composite fuels Effective irradiation creep rate model Homogenization creep theory Irradiation swelling Large deformation

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Transient fuel performance analysis of UO_(2)–BeO fuel with composite SiC coated with Cr cladding based on multiphysics method

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Nuclear science and Techniques 2023年第12期34卷 93-108页

作者： Chun‑Yu Yin Shi‑Xin Gao Sheng‑Yu Liu Rong Liu Guang‑Hui Su Li‑Bo Qian School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China School of Electric Power South China University of TechnologyGuangzhou 510640China

The transient multiphysics models were updated in CAMPUS to evaluate the accident-tolerant fuel performance under accident *** is a fuel performance code developed based on *** simulated results of the UO_(2)–Zircaloy fuel performance under accident conditions were compared with those of the FRAPTRAN code and the experimental data to verify the correctness of the updated ***,multiphysics models of the UO_(2)–BeO fuel and composite SiC coated with Cr(SiC_(f)/SiC-Cr)cladding were implemented in ***,the fuel performance of the three types of fuel cladding systems under Loss of Coolant Accident(LOCA)and Reactivity Insertion Accident(RIA)conditions was evaluated and compared,including the temperature distribution,stress distribution,pressure evolution,and cladding failure *** results showed that the fuel temperature of the UO_(2) fuel under accident conditions without pre-irradiation was lower after being combined with SiC_(f)/SiC-Cr ***,the centerline and outer surface temperatures of the UO_(2)–BeO fuel combined with SiC_(f)/SiC-Cr cladding reduced further under accident *** cladding temperature increased after the combination with the SiC_(f)/SiC-Cr cladding under accident conditions with *** addition,the use of SiC_(f)/SiC-Cr cladding significantly reduced the cladding hoop strain and plenum pressure.

关键词： Accident condition Fuel performance UO2–BeO fuel SiCf/SiC-Cr cladding

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Modeling of irradiation-induced damage and failure behaviors of fuel foil/cladding interface in UMo/Zr monolithic fuel plates

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Nuclear science and Techniques 2022年第5期33卷 16-29页

作者： Xiang-Zhe Kong Xiao-Bin Jian Feng Yan Chang-Bing Tang Zi-Xuan Guo Shu-Rong Ding Yuan-Ming Li Chun-Yu Yin Institute of Mechanics and Computational Engineering Department of Aeronautics and AstronauticsFudan UniversityShanghai 200433China Science and Technology On Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China

Models to describe the damage and fracture behaviors of the interface between the fuel foil and cladding in UMo/Zr monolithic fuel plates were established and numerically *** effects of the interfacial cohesive strength and cohesive energy on the irradiationinduced thermal-mechanical behaviors of fuel plates were *** results indicated that for heterogeneously irradiated fuel plates:(1)interfacial damage and failure were predicted to be initiated near the fuel foil corner with higher fission densities,accompanied by the formation of a large gap after interface failure,which was consistent with some experimental observations;high tensile stresses in the fuel foil occurred near the edges of the failed interface,attributed to through-thickness cracking of the fuel foil,as found in some post-irradiation examinations;(2)the cohesive strength and cohesive energy of the interface both influenced the in-pile evolution behaviors of fuel plates;a lower cohesive strength or cohesive energy resulted in faster interfacial damage;(3)after interface fracture,the thickness of the whole plate increased to a greater degree(by~20%)than that of the samples without interfacial damage,which was attributed to the locally enhanced Mises stresses and the nearby creep deformations around the cracked *** study provided a theoretical basis for assessing failure in fuel elements.

关键词： UMo/Zr Irradiation-inducedthermo-mechanicalbehavior Numericalsimulation Cohesive model Interfacialfailure

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Development of high-strength,low-cost wrought Mg–2.0 mass% Zn alloy with high Mn content

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Progress in Natural science:Materials International 2016年第6期26卷 630-635页

作者： Fusheng.Pan Jianjun Mao Gen Zhang Aitao Tang Jia She College of Materials Science and Engineering Chongqing University National Engineering Research Center for Magnesium Alloys Chongqing University Chongqing Research Center for Advanced Materials Chongqing Academy of Science and Technology Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China

Mg–Zn–Mn-based alloys have received considerable attention because of their high creep resistance, strength,and good corrosion resistance. The alloying element Mn in Mg–Zn-based alloys is commonly less than 1 wt%. In the present study, the effect of high Mn content(1 wt% and 2 wt%) on the microstructures and mechanical properties of Mg–2Zn–0.3Sr extruded alloy was investigated. The results revealed that the high Mn content significantly increased the ultimate tensile strength, tensile yield strength, compress yield strength, and yield asymmetry of the alloy without affecting its ductility. The dynamically recrystallized(DRXed) grains of Mg–2Zn–0.3Sr were remarkably refined because of the large amount of fine Mn precipitates in the homogenized alloy. The improved strengths were mainly attributed to the fine DRXed grains according to the Hall–Petch effect and to the large amount of spherical and < 0001 > Mn precipitates through the precipitation and dispersion strengthening. The fine DRXed grains and numerous Mn precipitates effectively suppressed the extension twining, substantially enhanced the compress yield strength, and resulted in improved anisotropy.

关键词： Magnesium alloy Mg–Zn alloy Microstructure Ultra-fine grains Second phase Mechanical properties

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Optimization of spatial structure designs of control rod using Monte Carlo code RMC

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Frontiers in Energy 2021年第4期15卷 974-983页

作者： Hao LUO Mancang LI Shanfang HUANG Minyun LIU Kan WANG Department of Engineering Physics Tsinghua UniversityBeijing 100084China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology China National Nuclear Corporation Nuclear Power Institute of ChinaChengdu 610213China

Control rod is the most important approach to control reactivity in reactors,which is currently a cluster of pins filled with boron carbide(B4C).In this case,neutrons are captured in the outer region,and thus the inner absorber is ***,the lifetime of the control rod is challenged due to the high reactivity worth loss resulted from the excessive degradation of B4C in the high flux *** this work,some control rod designs are proposed with optimized spatial structures including the spatially mixed rod,radially moderated rod,and composite control rod with small-sized *** control rod worth and effective absorption cross section of these designs are computed using the Monte Carlo code RMC.A long-time depletion calculation is conducted to evaluate their burnup *** the spatially mixed rod,rare-earth absorbers are combined with B4C in spatial *** with the homogenous B4C rod,mixed designs ensure more sufficient reactivity worth in the lifetime of the *** minimum reactivity loss at the end of the cycle is only 1.8%from the dysprosium titanate rod,while the loss for pure B4C rod is nearly 12%.For the radially moderated design,a doubled neutronic efficiency is achieved when the volume ratio of moderator equals approximately 0.3,while excessive moderating may lead to the failure of control *** control rod with small-sized pins processes an enhanced safety performance and saves the investment in *** rod worth can be further enhanced by introducing small moderator pins,and the reactivity loss caused by the reduction of absorbers is sustainable.

关键词： control rod optimized spatial structure neutronic performance burnup stability

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