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Circulation Background and Genesis Mechanism of a Cold Vortex over the Tibetan Plateau during Late April 2018

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Advances in Atmospheric Sciences 2024年第6期41卷 1201-1216页

作者： Duming GAO Jiangyu MAO Guoxiong WU Yimin LIU State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province Institute of Plateau MeteorologyChina Meteorological AdministrationChengdu 610072China Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China

A cold vortex occurred over the northeastern Tibetan Plateau(TP)on 27 April 2018 and subsequently brought excessive rainfall to the spring farming area in southern China when moving *** study investigates the genesis mechanism of the cold TP vortex(TPV)by diagnosing reanalysis data and conducting numerical *** demonstrate that the cold TPV was generated in a highly baroclinic environment with significant contributions of positive potential vorticity(PV)forcing from the tropopause and diurnal thermodynamic impact from the *** a positive PV anomaly in the lower stratosphere moved towards the TP,the PV forcing at the tropopause pushed the tropospheric isentropic surfaces upward,forming isentropic-isplacement ascent and reducing static stability over the *** descent of the tropopause over the TP also produced a tropopause folding over the northeastern TP associated with a narrow high-PV column intruding downwards over the TPV genesis site,resulting in ascending air in the free ***,in conjunction with the descending air in the valley area during the night,produced air stretching just at the TPV genesis *** the surface cooling at night increased the surface static stability,the aforementioned vertical air-stretching thus converted the produced static stability to vertical ***,the cold TPV was generated over the valley at night.

关键词： tropopause PV forcing air column stretching static stability vertical vorticity

Benchmark experiment on slab^(238)U with D-T neutrons for validation of evaluated nuclear data

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Nuclear Science and Techniques 2024年第2期35卷 145-159页

作者： Yan-Yan Ding Yang-Bo Nie Yue Zhang Zhi-Jie Hu Qi Zhao Huan-Yu Zhang Kuo-Zhi Xu Shi-Yu Zhang Xin-Yi Pan Chang-Lin Lan Jie Ren Xi-Chao Ruan Key Laboratory of Nuclear Data China Institute of Atomic EnergyBeijing 102413China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China institute of fluid Physics China Academy of Engineering PhysicsMianyang 62100China

A benchmark experiment on^(238)U slab samples was conducted using a deuterium-tritium neutron source at the China institute of Atomic *** leakage neutron spectra within energy levels of 0.8-16 MeV at 60°and 120°were measured using the time-of-flight *** samples were prepared as rectangular slabs with a 30 cm square base and thicknesses of 3,6,and 9 *** leakage neutron spectra were also calculated using the MCNP-4C program based on the latest evaluated files of^(238)U evaluated neutron data from CENDL-3.2,ENDF/B-Ⅷ.0,JENDL-5.0,and *** on the comparison,the deficiencies and improvements in^(238)U evaluated nuclear data were *** results showed the following.(1)The calculated results for CENDL-3.2 significantly overestimated the measurements in the energy interval of elastic scattering at 60°and 120°.(2)The calculated results of CENDL-3.2 overestimated the measurements in the energy interval of inelastic scattering at 120°.(3)The calculated results for CENDL-3.2 significantly overestimated the measurements in the 3-8.5 MeV energy interval at 60°and 120°.(4)The calculated results with JENDL-5.0 were generally consistent with the measurement results.

关键词： Leakage neutron spectra Uranium D-T neutron source Evaluated nuclear data

Deep electrical structures of Qinzhou-Fangcheng Junction Zone in Guangxi and seismogenic environment of the 1936 Lingshan M6^(3/4)earthquake

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Science China Earth Sciences 2024年第2期67卷 584-603页

作者： Bin ZHOU Chunheng YAN Yan ZHAN Xiangyu SUN Sha LI Xiang WEN Yajun MO Yongdong YUAN Yuan YUAN Meili HUANG Earthquake Agency of Guangxi Zhuang Autonomous Region Nanning530022China State Key Laboratory of Earthquake dynamics Institute of GeologyChina Earthquake AdministrationBeijing100029China Guangxi Geophysical Survey institute Liuzhou545005China

The tectonic position of the southwest section of the Qinzhou Bay-Hangzhou Bay Tectonic Junction Zone(QHTJZ)can be determined by examining the Qinzhou-Fangcheng Junction Zone(QFJZ)in *** zone is significant because it was the location of the largest earthquake ever recorded in the inland region of South China,specifically the 1936 Lingshan M6^(3/4)earthquake in ***,this region serves as an optimal location for researching the origins of intraplate earthquakes in South *** study presents a display of a broadband magnetotelluric(MT)prospecting profile that traverses the Guangxi QFJZ and the Lingshan earthquake zone,extending from the northwest(NW)to the southeast(SE).A resistivity structure model was generated using three-dimensional(3D)inversion technology along the *** main faults in QFJZ were analyzed in terms of their deep extension forms and tectonic *** analysis was performed by integrating the results obtained from geology,gravity,wave velocity ratio,Global Position System(GPS),and geothermal *** results showed that(1)the Dongzhong-Xiaodong fault(DXf),the eastern Fangcheng-Lingshan fault(FLf2),and the eastern Hepu-Beiliu fault(HBf2)were all trans-crustal deep faults,and crust-mantle ductile shear zones developed in the deep *** electrical boundary zones,DXf and HBf2,were *** inclined towards the northwest,while HBf2 inclined towards the *** FangchengLingshan fault(FLf)exhibits a tectonic style resembling a“flower”shape in the upper *** the deeper section,it is characterized by an electrical boundary zone that gradually slopes towards the southeast direction.(2)The Hunan-Guangxi Passive Continental Margin(HGPCM)on the NW side of DXf had a stratified resistivity structure and relatively stable Bouguer gravity anomalies,which conformed to the quasi-craton tectonic attribute of the local failure at the southeastern margin of the Yangtze Block(YB).The southeastern side of this bloc

关键词： South China Block Qinzhou-Fangcheng Junction Zone Magnetotelluric 1936 Lingshan M6^(3/4)earthquake Deep seismogenic environment

Comparing two IBM implementations for the simulation of uniform packed beds

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Particuology 2024年第3期86卷 1-12页

作者： Christian Gorges Maximilian Brommer Christin Velten Siegmar Wirtz Enric Illana Mahiques Viktor Scherer Katharina Zahringer Berend van Wachem Mechanical Process Engineering Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany Department of Energy Plant Technology Ruhr-Universitat BochumUniversitatsstraBe 15044780BochumGermany Laboratory of fluid dynamics and Technical Flows Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany

Nowadays,the design of fixed packed bed reactors still relies on empirical correlations,which,especially for small tube to particle diameter ratios,are mostly too inaccurate because of the presence of wall ***,the simulation of fixed packed bed reactors plays an important role to predict and control the flow and process parameters in such,nowadays and in the *** of its straightforward applicability to non-uniform packings with particles of arbitrary shapes,the immersed boundary method(IBM)has advantages over other numerical methods and is used more and more *** paper compares two approaches of IBMs for the simulation of fixed bed reactors with spherical shaped *** classic,smooth approach is compared to the straightforward to implement blocked-off method for velocity fields above the fixed bed for particle Reynolds numbers of 300 and *** from experimental inline PIV-measurements of the reactor to be simulated serve as a basis for *** good agreement with the experiment is found for both simulation methodologies with higher resolutions,considering the more stable flow at a particle Reynolds number of *** in the different IBM approaches occurred for the more unsteady flow at a particle Reynolds number of *** to the blocked-off method,the smooth IBM reflects the formation of additional jets and recirculation zones better right above the bed,though increasing the fluid mesh resolution improves the accuracy of the blocked-off ***,a more diffusive behaviour is found for the blocked-off simulations due to the stairstep representation,which is avoided by using interpolation stencils as in the smooth *** higher mesh refinement in the blocked-off IBM this effect can be reduced,but this also increases the computational effort.

关键词： Immersed boundary method Packed bed reactor Uniform particle packing

Study on damage mechanism and damage distribution of the rear plate under impact of debris cloud

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Defence Technology（防务技术） 2024年第5期35卷 151-167页

作者： Chenyang Wu Xiaowei Chen Qiguang He State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyHaidian DistrictBeijing 100081China School of Mechatronical Engineering Beijing Institute of TechnologyHaidian DistrictBeijing 100081China institute of fluid Physics China Academy of Engineering PhysicsMianyang 621900SichuanChina

The debris cloud generated by the hypervelocity impact(HVI)of orbiting space debris directly threatens the spacecraft.A full understanding of the damage mechanism of rear plate is useful for the optimal design of protective *** this study,the hypervelocity yaw impact of a cylindrical aluminum projectile on a double-layer aluminum plate is simulated by the FE-SPH adaptive method,and the damage process of the rear plate under the impact of the debris cloud is analyzed based on the debris cloud *** damage process can be divided into the main impact stage of the debris cloud and the structural response of the rear *** main impact stage lasts a short time and is the basis of the rear plate *** the stage of structure response,the continuous deformation and inertial motion of the rear plate dominate the perforation of the rear *** further analyze the damage mechanism and damage distribution characteristics of the rear plate in ***,the connection between velocity space and position space of the debris cloud is established,which promotes the general analysis of the damage law of debris *** on the relationship,the features of typical damage areas are identified by the localized fine *** the cumulative effect and structural response cause the perforation of rear plate;in the non-perforated area,cratering by the impact of hazardous fragments is the main damage mode of the rear plate.

关键词： Damage of rear plate Debris cloud Secondary impact Hypervelocity yaw impact FE-SPH adaptive method

路面谱随机激励下的轮式发射系统动力学建模与仿真

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Acta Mechanica Sinica 2024年第5期40卷 161-174页

作者：伍根洋芮筱亭王国平江民王勋 institute of Launch dynamics Nanjing University of Science and Technology Nanjing China National Key Laboratory of Complex Multibody System dynamics Nanjing China

轮式发射系统行驶动力学建模与仿真是其动力学性能和试验设计的前提和基础,日益提高的轮式发射系统动态性能迫切需要一种快速高效的大型多体系统动力学计算方法。本文采用多体系统传递矩阵法建立了轮式发射系统的动力学模型,给出了相应... 详细信息

轮式发射系统行驶动力学建模与仿真是其动力学性能和试验设计的前提和基础,日益提高的轮式发射系统动态性能迫切需要一种快速高效的大型多体系统动力学计算方法。本文采用多体系统传递矩阵法建立了轮式发射系统的动力学模型,给出了相应的拓扑图和动力学方程,此外,通过快速傅里叶逆变换重构了平行车轮的路面不平度,结合蒙特卡罗方法对随机路面激励下轮式发射系统的动力学特性进行了模拟和讨论分析结果表明,随着路面不平度级别和行驶速度的增加,轮式发射系统的振动加速度幅值越大,在正常车速下,路面激励对车体的影响远大于车速。模态试验和行驶试验验证了动力学建模和仿真的正确性本文可拓展到其他包含概率不确定性的多体系统动力学建模和分析.

关键词：路面不平度行驶速度多体系统动力学加速度幅值路面激励行驶试验随机激励路面谱

Identifying and localizing of seismogenic electromagnetic anomalies from data observed by permanent MT stations

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Science China Earth Sciences 2024年第5期67卷 1698-1713页

作者： Bing HAN Wenbao HU Guoze ZHAO Ji TANG State Key Laboratory of Earthquake dynamics Institute of GeologyBeijing 100029China Key Laboratory of Exploration Technologies for Oil and Gas Resources of Ministry of Education Yangtze UniversityWuhan 430100China

In this research, an arbitrarily oriented electric dipole at subsurface is used to simulate Seismogenic Electromagnetic(SEM) radiation emanating from a seismic zone during its gestation phase. Analytical synthesis of responses at the Lijiang magnetotelluric(MT) station has revealed that SEM radiation could induce identifiable anomalies in the electromagnetic(EM)spectrum, apparent resistivity and phase within specific frequency bands. Background variations were extracted from long-term observation data of Dali and Lijiang MT stations, enabling the identification of SEM anomalies related to the Yunlong and Yangbi earthquakes. Multiple parameters of dipole sources at subsurface were obtained by applying the Differential Ant Colony Optimization(DACO) algorithm to anomalous data of two stations with multi-frequencies and various response functions. The spatial distribution of these predicted dipoles is predominantly clustered in or around the seismogenic area, with their azimuthal orientation aligning towards the seismogenic fault in general. This study has demonstrated the potential of using subsurface electric dipole simulations for SEM radiation analysis, offering a feasible approach for the prediction and understanding of seismogenic zones.

关键词： MT responses Identifying SEM anomaly Vector electric dipole responses Localizing SEM sources by inversion

Availability evaluation of controller area networks under the influence of intermittent connection faults

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Frontiers of Information Technology & Electronic Engineering 2024年第4期25卷 555-568页

作者： Longkai WANG Leiming ZHANG Yong LEI State Key Laboratory of fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China The 14th Research institute of China Electronics Technology Group Corporation Nanjing 210039China

Controller area networks(CANs),as one of the widely used fieldbuses in the industry,have been extended to the automation field with strict standards for safety and *** practice,factors such as fatigue and insulation wear of the cables can cause intermittent connection(IC)faults to occur frequently in the CAN,which will affect the dynamic behavior and the safety of the ***,quantitatively evaluating the performance of the CAN under the influence of IC faults is crucial to real-time health monitoring of the *** this paper,a novel methodology is proposed for real-time quantitative evaluation of CAN availability when considering IC faults,with the system availability parameter being calculated based on the network state transition ***,the causal relationship between IC fault and network error response is constructed,based on which the IC fault arrival rate is ***,the states of the network considering IC faults are analyzed,and the deterministic and stochastic Petri net(DSPN)model is applied to describe the transition relationship of the ***,the parameters of the DSPN model are determined and the availability of the system is calculated based on the probability distribution and physical meaning of markings in the DSPN model.A testbed is constructed and case studies are conducted to verify the proposed methodology under various experimental *** results show that the estimation results obtained using the proposed method agree well with the actual values.

关键词： Controller area network Intermittent connection fault Arrival rate Deterministic and stochastic Petri net Availability evaluation

Deep-learning-assisted online surface roughness monitoring in ultraprecision fly cutting

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Science China(Technological Sciences) 2024年第5期67卷 1482-1497页

作者： SHEHZAD Adeel RUI XiaoTing DING YuanYuan ZHANG JianShu CHANG Yu LU HanJing CHEN YiHeng institute of Launch dynamics Nanjing University of Science and TechnologyNanjing210094China National Key Laboratory of Complex Multibody System dynamics Nanjing210094China Automotive Engineering Centre University of Engineering and TechnologyLahore54890Pakistan School of Science Nanjing University of Science and TechnologyNanjing210094China College of Engineering Peking UniversityBeijing100871China

Surface roughness is one of the most critical attributes of machined components,especially those used in high-performance *** surface roughness monitoring offers advancements comparable to post-process inspection methods,reducing inspection time and costs and concurrently reducing the likelihood of ***,online monitoring approaches for surface roughness are constrained by several limitations,including the reliance on handcrafted feature extraction,which necessitates the involvement of human experts and entails time-consuming ***,the prediction models trained under one set of cutting conditions exhibit poor performance when applied to different experimental *** address these challenges,this work presents a novel deep-learning-assisted online surface roughness monitoring method for ultraprecision fly cutting of copper workpieces under different cutting *** acceleration signals were acquired during each cutting experiment to develop two datasets,and no handcrafted features were *** deep learning models were developed and evaluated using standard performance metrics.A convolutional neural network stacked on a long short-term memory network outperformed all other network models,yielding exceptional results,including a mean absolute percentage error as low as 1.51%and an R2value of 96.6%.Furthermore,the robustness of the proposed model was assessed via a validation cohort analysis using experimental data obtained using cutting parameters different from those previously *** performance of the model remained consistent and commendable under varied conditions,asserting its applicability in real-world scenarios.

关键词： online surface roughness monitoring UPFC deep learning CNN-LSTM vibration signal