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Data driven prediction of fragment velocity distribution under explosive loading conditions
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作者 Donghwan Noh Piemaan Fazily +4 位作者 Songwon Seo Jaekun Lee Seungjae Seo Hoon Huh Jeong Whan Yoon 《Defence Technology(防务技术)》 2025年第1期109-119,共11页
This study presents a machine learning-based method for predicting fragment velocity distribution in warhead fragmentation under explosive loading condition.The fragment resultant velocities are correlated with key de... This study presents a machine learning-based method for predicting fragment velocity distribution in warhead fragmentation under explosive loading condition.The fragment resultant velocities are correlated with key design parameters including casing dimensions and detonation positions.The paper details the finite element analysis for fragmentation,the characterizations of the dynamic hardening and fracture models,the generation of comprehensive datasets,and the training of the ANN model.The results show the influence of casing dimensions on fragment velocity distributions,with the tendencies indicating increased resultant velocity with reduced thickness,increased length and diameter.The model's predictive capability is demonstrated through the accurate predictions for both training and testing datasets,showing its potential for the real-time prediction of fragmentation performance. 展开更多
关键词 Data driven prediction Dynamic fracture model Dynamic hardening model fragmentATION fragment velocity distribution High strain rate Machine learning
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Characterization of combined blast-and fragments-induced synergetic damage in polyurea coated liquid-filled container
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作者 Chen Tao Chong Ji +3 位作者 Xin Wang Juan Gu Yuting Wang Changxiao Zhao 《Defence Technology(防务技术)》 2025年第1期201-224,共24页
Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves a... Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and fragments.To explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied experimentally.The microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were analyzed.The simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in detail.Finally,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared.Results showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the container.The polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between holes.Under the close-in blast,the detonation shock wave reached the LFC before the fragment.Polyurea does not all have an enhanced effect on the protection of LFC.The presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the container.The combined action has an enhancement effect on the deformation of the LFC.The depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition. 展开更多
关键词 POLYUREA Prefabricated fragment Liquid-filled container Hydrodynamic ram Cumulative effect
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Investigation on dynamic response of liquid-filled cylindrical shellstructures under the action of combined blast and fragments loading
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作者 Zhujie Zhao Hailiang Hou +4 位作者 Dian Li Xiaowei Wu Yongqing Li Zhenghan Chen Linzhi Wu 《Defence Technology(防务技术)》 2025年第7期334-354,共21页
This study designs four types of liquid-filled cylindrical shell structures to investigate their protection characteristics against explosive shock waves and high-speed fragments.Bare charge and charge-driven prefabri... This study designs four types of liquid-filled cylindrical shell structures to investigate their protection characteristics against explosive shock waves and high-speed fragments.Bare charge and charge-driven prefabricated fragments are employed to examine the damage under blast shock waves and combined blast and fragments loading on various liquid-filled cylindrical shell structures.The test results are compared to numerical calculations and theoretical analysis for the structure's deformation,the liquid medium's movement,and the pressure waves'propagation characteristics under different liquid-filling methods.The results showed that the filling method influences the blast protection and the struc-ture's energy absorption performance.The external filling method reduces the structural deformation,and the internal filling method increases the damage effect.The gapped internal filling method improves the structure's energy absorption efficiency.The pressure wave loading on the liquid-filled cylindrical shell structure differs depending on filling methods.Explosive shock waves and high-speed fragments show a damage enhancement effect on the liquid-filled cylindrical shell structure,depending on the thickness of the internal liquid container layer.The specific impulse on the inner surface of the cylindrical shell positively correlates to the radial deformation of the cylindrical shell structure,and the external liquid layer limits the radial structural deformation. 展开更多
关键词 Blast wave Combined blast and fragments loading Filling method Liquid-filled structure Dynamic response
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Impact safety of CL-20-based explosive charge using detonation driving high velocity fragments
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作者 Gangling Jiao Tianchu Wang +3 位作者 Longjie Huang Chuanguo Ma Rui Liu Pengwan Chen 《Defence Technology(防务技术)》 2025年第6期298-305,共8页
The impact safety of explosive charges has been focused in these decades. The fragment impact is widely used to evaluate the response of explosive charges. In our work, the explosive detonation driving technique was u... The impact safety of explosive charges has been focused in these decades. The fragment impact is widely used to evaluate the response of explosive charges. In our work, the explosive detonation driving technique was used to generate a high velocity fragment with large mass. When the fragment masses are10 g, 16 g, 25 g, and 50 g, the highest velocity of fragments can reach 2400 m/s, 2100 m/s, 1900 m/s, and1400 m/s, respectively. The high velocity fragment with large mass was used to evaluate the safety of two kinds of CL-20 based explosive charges. The effects of the fragment mass and velocity were analyzed.Especially, the reaction extent was obtained based on visible phenomenon. The CL-20-based explosive charge containing Al had a higher safety level than that without Al. It was because Al had good ductility,and further improved the mechanical property of the material. Also, the numerical simulation was conducted to understand the reaction characteristics of the CL-20-based explosive charge. The results showed that as the fragment mass and velocity increased, the reaction became more violent. 展开更多
关键词 Impact safety Detonation driving fragments CL-20-Based explosive charge Reaction characteristics
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Application of gurney and flight of fragment calculations for water jet velocities in explosive applications
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作者 Rachel L.Bauer Tate B.Friedrich Catherine E.Johnson 《Defence Technology(防务技术)》 2025年第7期68-78,共11页
This study investigates the application of Gurney and flight of fragment equations,typically used to predict metal fragment velocities,in modeling the water jet behavior.Three shotgun cartridge sizes were used as the ... This study investigates the application of Gurney and flight of fragment equations,typically used to predict metal fragment velocities,in modeling the water jet behavior.Three shotgun cartridge sizes were used as the energy source:2.59 g,5.83 g,and 7.13 g.Two configurations were tested:standard(full-barrel water load)and"negative 8"(partial water load).High-speed footage captured water column velocities,and Gurney models,including infinitely tamped and open-faced configurations,combined with the flight of fragment model were used to assess prediction accuracy.Results showed charge strength significantly affects water column velocity,with higher strengths yielding greater stability and velocity retention over distance.The infinitely tamped Gurney model closely predicted experimental velocities,deviating by as little as 1.4%for standard charges and 2.8% for negative 8 charges.Additionally,interesting dynamics such as a 1-2°rise in jet height and the rear overtaking the front was observed.These findings have significant implications for optimizing PAN disruptors and enhancing performance in high-velocity fluid applications and explosive breaching systems. 展开更多
关键词 Gurney calculations Water driven projectile Flight of fragment Incompressible fluid dynamics Optical velocity measurement
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A novel detection method for warhead fragment targets in optical images under dynamic strong interference environments
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作者 Guoyi Zhang Hongxiang Zhang +4 位作者 Zhihua Shen Deren Kong Chenhao Ning Fei Shang Xiaohu Zhang 《Defence Technology(防务技术)》 2025年第1期252-270,共19页
A measurement system for the scattering characteristics of warhead fragments based on high-speed imaging systems offers advantages such as simple deployment,flexible maneuverability,and high spatiotemporal resolution,... A measurement system for the scattering characteristics of warhead fragments based on high-speed imaging systems offers advantages such as simple deployment,flexible maneuverability,and high spatiotemporal resolution,enabling the acquisition of full-process data of the fragment scattering process.However,mismatches between camera frame rates and target velocities can lead to long motion blur tails of high-speed fragment targets,resulting in low signal-to-noise ratios and rendering conventional detection algorithms ineffective in dynamic strong interference testing environments.In this study,we propose a detection framework centered on dynamic strong interference disturbance signal separation and suppression.We introduce a mixture Gaussian model constrained under a joint spatialtemporal-transform domain Dirichlet process,combined with total variation regularization to achieve disturbance signal suppression.Experimental results demonstrate that the proposed disturbance suppression method can be integrated with certain conventional motion target detection tasks,enabling adaptation to real-world data to a certain extent.Moreover,we provide a specific implementation of this process,which achieves a detection rate close to 100%with an approximate 0%false alarm rate in multiple sets of real target field test data.This research effectively advances the development of the field of damage parameter testing. 展开更多
关键词 Damage parameter testing Warhead fragment target detection High-speed imaging systems Dynamic strong interference disturbance suppression Variational bayesian inference Motion target detection Faint streak-like target detection
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Enhancing rock fragmentation prediction in mining operations:A hybrid GWO-RF model with SHAP interpretability 被引量:3
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作者 ZHANG Yu-lin QIU Yin-gui +2 位作者 ARMAGHANI Danial Jahed MONJEZI Masoud ZHOU Jian 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第8期2916-2929,共14页
In the mining industry,precise forecasting of rock fragmentation is critical for optimising blasting processes.In this study,we address the challenge of enhancing rock fragmentation assessment by developing a novel hy... In the mining industry,precise forecasting of rock fragmentation is critical for optimising blasting processes.In this study,we address the challenge of enhancing rock fragmentation assessment by developing a novel hybrid predictive model named GWO-RF.This model combines the grey wolf optimization(GWO)algorithm with the random forest(RF)technique to predict the D_(80)value,a critical parameter in evaluating rock fragmentation quality.The study is conducted using a dataset from Sarcheshmeh Copper Mine,employing six different swarm sizes for the GWO-RF hybrid model construction.The GWO-RF model’s hyperparameters are systematically optimized within established bounds,and its performance is rigorously evaluated using multiple evaluation metrics.The results show that the GWO-RF hybrid model has higher predictive skills,exceeding traditional models in terms of accuracy.Furthermore,the interpretability of the GWO-RF model is enhanced through the utilization of SHapley Additive exPlanations(SHAP)values.The insights gained from this research contribute to optimizing blasting operations and rock fragmentation outcomes in the mining industry. 展开更多
关键词 BLASTING rock fragmentation random forest grey wolf optimization hybrid tree-based technique
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Double casing warhead with sandwiched charge:The axial distribution of fragments velocities 被引量:1
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作者 Ping Ye Yongxiang Dong +5 位作者 Qitian Sun Peizhuo Shi Wang Yao Yongnan Li Yujing Li Mingze Li 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第4期201-216,共16页
The double casing warhead with sandwiched charge is a novel fragmentation warhead that can produce two groups of fragments with different velocity,and the previous work has presented a calculation formula to determine... The double casing warhead with sandwiched charge is a novel fragmentation warhead that can produce two groups of fragments with different velocity,and the previous work has presented a calculation formula to determine the maximum fragment velocity.The current work builds on the published formula to further develop a formula for calculating the axial distribution characteristics of the fragment velocity.For this type of warhead,the simulation of the dispersion characteristics of the detonation products at different positions shows that the detonation products at the ends have a much larger axial velocity than those in the middle,and the detonation products have a greater axial dispersion velocity when they are closer to the central axis.The loading process and the fragment velocity vary with the axial position for both casing layers,and the total velocity of the fragments is the vector sum of the radial velocity and the axial velocity.At the same axial position,the acceleration time of the inner casing is greater than that of the outer casing.For the same casing,the fragments generated at the ends have a longer acceleration time than the fragments from the middle.The proposed formula is validated with the X-ray radiography results of the four warheads previously tested experimentally and the 3D smoothedparticle hydrodynamics numerical simulation results of several series of new warheads with different configurations.The formula can accurately and reliably calculate the fragment velocity when the lengthto-diameter ratio of the charge is greater than 1.5 and the thickness of the casing is less than 20%its inner radius.This work thus provides a key reference for the theoretical analysis and the design of warheads with multiple casings. 展开更多
关键词 Double casing warhead Sandwiched charge fragment velocity Rarefaction wave Gurney formula Explosive loading
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Fracture behavior and mechanism of highly fragmented steel cylindrical shell under explosive loading
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作者 Kang Wang Peng Chen +5 位作者 Xingyun Sun Yufeng Liu Jiayu Meng Xiaoyuan Li Xiongwei Zheng Chuan Xiao 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第6期122-132,共11页
An in-depth understanding of the fracture behavior and mechanism of metallic shells under internal explosive loading can help develop material designs for warheads and regulate the quantity and mass distribution of th... An in-depth understanding of the fracture behavior and mechanism of metallic shells under internal explosive loading can help develop material designs for warheads and regulate the quantity and mass distribution of the fragments formed.This study investigated the fragmentation performance of a new high-carbon silicon-manganese(HCSiMn)steel cylindrical shell through fragment recovery experiments.Compared with the conventional 45Cr steel shell,the number of small mass fragments produced by the HCSi Mn steel shell was significantly increased with a scale parameter of 0.57 g fitted by the Weibull distribution model.The fragmentation process of the HCSi Mn shell exhibited more brittle tensile fracture characteristics,with the microcrack damage zone on the outer surface being the direct cause of its high fragmentation.On the one hand,the doping of alloy elements resulted in grain refinement by forming metallographic structure of tempered sorbite,so that microscopic intergranular fracture reduces the characteristic mass of the fragments;on the other hand,the distribution of alloy carbides can exert a"pinning"effect on the substrate grains,causing more initial cracks to form and propagate along the brittle carbides,further improving the shell fragmentation.Although the killing power radius for light armored vehicles was slightly reduced by about 6%,the dense killing radius of HCSiMn steel projectile against personnel can be significantly increased by about 26%based on theoretical assessment.These results provided an experimental basis for high fragmentation warhead design,and to some extent,revealed the correlation mechanism between metallographic structure and shell fragmentation. 展开更多
关键词 Projectile fragmentation fragment mass distribution Fracture mode Metallographic structure Damage power
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Warhead fragments motion trajectories tracking and spatio-temporal distribution reconstruction method based on high-speed stereo photography
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作者 Pengyu Hu Jiangpeng Wu +3 位作者 Zhengang Yan Meng He Chao Liang Hao Bai 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第7期162-172,共11页
High speed photography technique is potentially the most effective way to measure the motion parameter of warhead fragment benefiting from its advantages of high accuracy,high resolution and high efficiency.However,it... High speed photography technique is potentially the most effective way to measure the motion parameter of warhead fragment benefiting from its advantages of high accuracy,high resolution and high efficiency.However,it faces challenge in dense objects tracking and 3D trajectories reconstruction due to the characteristics of small size and dense distribution of fragment swarm.To address these challenges,this work presents a warhead fragments motion trajectories tracking and spatio-temporal distribution reconstruction method based on high-speed stereo photography.Firstly,background difference algorithm is utilized to extract the center and area of each fragment in the image sequence.Subsequently,a multi-object tracking(MOT)algorithm using Kalman filtering and Hungarian optimal assignment is developed to realize real-time and robust trajectories tracking of fragment swarm.To reconstruct 3D motion trajectories,a global stereo trajectories matching strategy is presented,which takes advantages of epipolar constraint and continuity constraint to correctly retrieve stereo correspondence followed by 3D trajectories refinement using polynomial fitting.Finally,the simulation and experimental results demonstrate that the proposed method can accurately track the motion trajectories and reconstruct the spatio-temporal distribution of 1.0×10^(3)fragments in a field of view(FOV)of 3.2 m×2.5 m,and the accuracy of the velocity estimation can achieve 98.6%. 展开更多
关键词 Warhead fragment measurement High speed photography Stereo vision Multi-object tracking Spatio-temporal reconstruction
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A cloud model target damage effectiveness assessment algorithm based on spatio-temporal sequence finite multilayer fragments dispersion
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作者 Hanshan Li Xiaoqian Zhang Junchai Gao 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第10期48-64,共17页
To solve the problem of target damage assessment when fragments attack target under uncertain projectile and target intersection in an air defense intercept,this paper proposes a method for calculating target damage p... To solve the problem of target damage assessment when fragments attack target under uncertain projectile and target intersection in an air defense intercept,this paper proposes a method for calculating target damage probability leveraging spatio-temporal finite multilayer fragments distribution and the target damage assessment algorithm based on cloud model theory.Drawing on the spatial dispersion characteristics of fragments of projectile proximity explosion,we divide into a finite number of fragments distribution planes based on the time series in space,set up a fragment layer dispersion model grounded in the time series and intersection criterion for determining the effective penetration of each layer of fragments into the target.Building on the precondition that the multilayer fragments of the time series effectively assail the target,we also establish the damage criterion of the perforation and penetration damage and deduce the damage probability calculation model.Taking the damage probability of the fragment layer in the spatio-temporal sequence to the target as the input state variable,we introduce cloud model theory to research the target damage assessment method.Combining the equivalent simulation experiment,the scientific and rational nature of the proposed method were validated through quantitative calculations and comparative analysis. 展开更多
关键词 Target damage Cloud model fragments dispersion Effectiveness assessment Spatio-temporal sequence
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灾害风险应急管理敏捷能力的生成逻辑 被引量:4
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作者 韩广华 钱伟宏 《上海交通大学学报(哲学社会科学版)》 北大核心 2025年第3期64-78,共15页
灾害风险日益呈现出高频次、大规模、致灾复杂和高度不确定性等特征,客观上要求应急管理系统具备灵敏感知、快速应对和适应变化的敏捷能力。然而,应急管理系统的碎片化不利于打造其敏捷能力。为此,本文基于敏捷治理理论和复杂适应系统理... 灾害风险日益呈现出高频次、大规模、致灾复杂和高度不确定性等特征,客观上要求应急管理系统具备灵敏感知、快速应对和适应变化的敏捷能力。然而,应急管理系统的碎片化不利于打造其敏捷能力。为此,本文基于敏捷治理理论和复杂适应系统理论,从应急管理碎片化的现实图景出发,构建提升应急管理敏捷能力的逻辑框架:一是打造集中管理和分散决策相互均衡的应急管理系统架构;二是加强应急管理系统运行控制系统的规范性与衔接性;三是通过平台和技术支撑应急管理系统的敏捷效能。在这个基础上,本文提出了强化危机学习、推行包容性文化、强化实训演练、转变考核方式等保障措施,以加速形成应急管理敏捷能力。 展开更多
关键词 碎片化 敏捷性 应急管理 逻辑框架 复杂系统
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海域盾构隧道孤石和基岩凸起段的精细化爆破预处理方法研究 被引量:1
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作者 魏海霞 崔有权 +4 位作者 陈建福 杨小林 褚怀保 祝杰 陈士海 《爆破》 北大核心 2025年第1期81-88,158,共9页
海域盾构施工中常遇到大粒径孤石和基岩凸起段,通常采用爆破法进行预处理,爆破预处理的效果是盾构机顺利通过的关键。依托厦门轨道交通2号线工程,综合考虑海域孤石和基岩凸起段的覆盖层条件、爆破块度控制指标及海洋生物安全控制标准,... 海域盾构施工中常遇到大粒径孤石和基岩凸起段,通常采用爆破法进行预处理,爆破预处理的效果是盾构机顺利通过的关键。依托厦门轨道交通2号线工程,综合考虑海域孤石和基岩凸起段的覆盖层条件、爆破块度控制指标及海洋生物安全控制标准,提出了一种盾构隧道孤石和基岩凸起段的精细化爆破预处理方法。具体步骤包括:爆破孔网参数设计;炸药单耗、单孔装药量、平均块度尺寸的计算;装药结构及爆破网路设计;爆破块度分布效果预测;考虑生态环境影响进一步优化爆破方案。现场应用结果表明:爆破预处理后的块度在30 cm以内,满足盾构机推进的块度尺寸要求;盾构机在爆破预处理段能够顺利掘进,与正常段推进参数基本相近。实现了海域盾构隧道孤石和基岩凸起段的精细化、生态化、高效化和安全化爆破施工。 展开更多
关键词 海域盾构 孤石 基岩凸起段 爆破预处理 块度
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农村医养结合整体性治理及其实现路径 被引量:4
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作者 姬雄华 邓慧 《卫生经济研究》 北大核心 2025年第3期6-9,共4页
目前,我国农村医养结合存在治理理念未统一、组织结构协调不畅、政策保障不足、技术支撑乏力等治理碎片化问题。对此,应以整体性治理理论为指引,对标农村健康老龄化要求,统一治理理念、提升组织结构协同性、进行政策整合、搭建数字化平... 目前,我国农村医养结合存在治理理念未统一、组织结构协调不畅、政策保障不足、技术支撑乏力等治理碎片化问题。对此,应以整体性治理理论为指引,对标农村健康老龄化要求,统一治理理念、提升组织结构协同性、进行政策整合、搭建数字化平台,实现农村医养结合的整体性治理。 展开更多
关键词 治理碎片化 农村医养结合 整体性治理
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面向CFD计算的离心泵蜗壳模型优化方法
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作者 谈明高 蒋振清 +2 位作者 刘厚林 吴贤芳 邵晨 《排灌机械工程学报》 北大核心 2025年第3期231-237,共7页
由于离心泵蜗壳模型结构较为复杂,在进行三维建模的过程中会进行大量复杂的几何操作,导致在CAD模型表面会出现碎面,使后续CFD计算的网格划分环节难以进行.为了解决此问题,首先对蜗壳水力图和三维模型进行分析,结合蜗壳模型中的碎面特点... 由于离心泵蜗壳模型结构较为复杂,在进行三维建模的过程中会进行大量复杂的几何操作,导致在CAD模型表面会出现碎面,使后续CFD计算的网格划分环节难以进行.为了解决此问题,首先对蜗壳水力图和三维模型进行分析,结合蜗壳模型中的碎面特点,给出了碎面定义;然后通过构建蜗壳CAD模型的属性邻接图,并利用拓扑信息和几何信息的映射关系实现了碎面识别;最后基于几何面的优化方法,针对蜗壳模型中存在碎面较多的曲面类型,根据其几何参数进行相应的基面构造,并使用基面对存在碎面的曲面进行拟合,完成了碎面修复.基于Open CASCADE平台实现了蜗壳优化算法,结合不同类型蜗壳应用实例证明了方法的正确性和有效性.研究成果能够为离心泵CAD/CFD一体化设计提供良好的技术支撑. 展开更多
关键词 离心泵 蜗壳 CAD模型 碎面修复 碎面识别
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截锥形战斗部舱内静动态爆炸下载荷特性研究
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作者 张琦 李俊 +3 位作者 彭帅 施锐 陈威 李晓彬 《船海工程》 北大核心 2025年第4期26-31,共6页
为掌握截锥型战斗部舱内爆炸载荷特性,开展静、动爆下载荷特性比对模型试验,结合数值仿真分析,探讨动态爆炸舱内冲击波、破片等典型载荷规律。结果表明,当战斗部以278 m/s的速度爆炸时,在战斗部运动前方的舱壁正中心处,动爆冲击波超压... 为掌握截锥型战斗部舱内爆炸载荷特性,开展静、动爆下载荷特性比对模型试验,结合数值仿真分析,探讨动态爆炸舱内冲击波、破片等典型载荷规律。结果表明,当战斗部以278 m/s的速度爆炸时,在战斗部运动前方的舱壁正中心处,动爆冲击波超压峰值约为静爆的1.14倍,动爆状态下战斗部运动方向的冲击波存在明显的增强效应,动爆状态下近端壳体的破片速度约为静爆状态下近端壳体速度的122.67%,静爆状态下破片飞散角为在78.9°~95.7°范围内,动爆状态下破片飞散角在69.4°~75.8°范围内。动爆状态下破片的飞散角比静爆状态下呈现向战斗部的运动方向偏移约14.7°。 展开更多
关键词 舱室内爆 动态爆炸 冲击波 破片
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含初始损伤饱水花岗岩的冲击破坏规律
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作者 褚怀保 陈璐阳 +3 位作者 杨小林 王东辉 魏海霞 孙博 《爆炸与冲击》 EI CAS 北大核心 2025年第1期51-64,共14页
为研究饱水和初始损伤对冲击荷载下花岗岩宏观和微观破坏特征的影响,开展了X射线衍射、霍普金森和扫描电镜试验,利用分形维数对花岗岩的破碎块度和断口形貌进行了分析,探讨了图像放大倍数对分形维数的影响,分析了冲击荷载下饱水后花岗... 为研究饱水和初始损伤对冲击荷载下花岗岩宏观和微观破坏特征的影响,开展了X射线衍射、霍普金森和扫描电镜试验,利用分形维数对花岗岩的破碎块度和断口形貌进行了分析,探讨了图像放大倍数对分形维数的影响,分析了冲击荷载下饱水后花岗岩的微观致裂机制。结果表明:饱水后花岗岩中角闪石、钠长石、微斜长石和石英的占比减少,高岭石占比显著提高;随着初始损伤的增大,花岗岩的动态峰值应力逐渐减小,而破碎程度和块度分形维数逐渐增大,且初始损伤对块度分形维数的影响大于饱水的影响;随着初始损伤的增加,断口出现更多的微裂纹和碎屑,断口图像的分形维数也逐渐增加;放大倍数在400~3200范围内时,断口图像分形维数随着图像放大倍数的增大而增加,超过3200后,分形维数减小。 展开更多
关键词 岩石动力学 矿物成分 破碎块度 断口微观形貌 分形维数
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小组弥合缝隙:数字政府建设中科层困境的组织纾解 被引量:1
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作者 刘桂芝 张司杰 《东北师大学报(哲学社会科学版)》 北大核心 2025年第4期60-68,共9页
技术与组织互嵌互构。数字政府建设在赋能科层治理的同时,也面临着科层桎梏。基于“情境—策略”框架,对S省“数字强省建设领导小组”案例进行分析研究发现:数字政府建设中的科层困境表现为结构、行动、监督上的“条块缝隙”,包括建设... 技术与组织互嵌互构。数字政府建设在赋能科层治理的同时,也面临着科层桎梏。基于“情境—策略”框架,对S省“数字强省建设领导小组”案例进行分析研究发现:数字政府建设中的科层困境表现为结构、行动、监督上的“条块缝隙”,包括建设标准碎片化、部门信息孤岛、政策悬浮、问责与避责间的张力等问题。作为突破科层制藩篱的组织选择,领导小组应采取“以块统条”“条块联动”“块监督条”等策略弥合“条块缝隙”。在缝隙弥合的过程中,领导小组可通过政治注意力分配形塑共识、党政结构嵌入调整职责、组织吸纳技术赋能协同等多重机制重塑条块关系,为加快数字政府建设奠定了良好的科层组织基础。 展开更多
关键词 数字政府 科层困境 领导小组 条块重塑 缝隙弥合
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经营规模、黑土地保护技术采纳与农地经营效率——农地细碎化的调节效应 被引量:1
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作者 黄善林 邓月洪 《中国土地科学》 北大核心 2025年第1期70-81,共12页
研究目的:完善经营规模与农地经营效率的作用机制研究,为推动农业高质量发展、保障国家粮食安全提供理论基础。研究方法:基于东北典型黑土区——三江平原672份农户问卷调查数据,采用随机前沿模型、中介效应模型、调节效应模型进行分析... 研究目的:完善经营规模与农地经营效率的作用机制研究,为推动农业高质量发展、保障国家粮食安全提供理论基础。研究方法:基于东北典型黑土区——三江平原672份农户问卷调查数据,采用随机前沿模型、中介效应模型、调节效应模型进行分析。研究结果:(1)经营规模与农地经营效率之间存在“倒U型”关系。(2)黑土地保护技术采纳在经营规模对农地经营效率的影响中发挥部分中介作用。(3)农地细碎化在黑土地保护技术采纳对农地经营效率的影响中起负向调节作用。(4)黑土地保护技术采纳对不同农户农地经营效率的带动效果存在差异,较兼业户和非示范区农户而言,对纯农户和示范区农户的效率提升有更明显的推动作用。研究结论:研究区应推动农地适度规模,同时扩大地块规模、促进农地集中连片,并加快黑土地保护技术的推广应用,提高农户农业生产的专业化水平,助力农户农地经营效率的提升。 展开更多
关键词 经营规模 黑土地保护技术采纳 农地细碎化 农地经营效率 三江平原
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基于多组分DQMOM模型的FCC辅助纳米颗粒混合体系流化研究
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作者 陈巨辉 陈轲 +4 位作者 李丹 杨天一 ZHURAVKOV Michael LAPATSIN Siarhel 姜文锐 《化工学报》 北大核心 2025年第6期2616-2625,共10页
根据纳米颗粒团聚和破碎的影响因素,基于Gidaspow曳力模型,修正了Re的计算方法,提出多组分DQMOM模型。数值模拟微型流化床内纳米颗粒流动过程及聚团数量与聚团直径的变化,实验值与模拟结果吻合较好,验证了微型流化床模型的准确性和可靠... 根据纳米颗粒团聚和破碎的影响因素,基于Gidaspow曳力模型,修正了Re的计算方法,提出多组分DQMOM模型。数值模拟微型流化床内纳米颗粒流动过程及聚团数量与聚团直径的变化,实验值与模拟结果吻合较好,验证了微型流化床模型的准确性和可靠性。对SiO_(2)和ZnO混合纳米颗粒进行模拟,探究添加大颗粒改善流化效果。结果表明,混合颗粒中流化性能较好的颗粒占比较高时,整体的流化性能会有所提升。当SiO_(2)颗粒含量较高时,小粒径颗粒改善流化性能的效果更好;当ZnO颗粒含量较高时,大密度颗粒效果更好。当流化性能好的颗粒含量较高时,添加少量大颗粒就可以有效改善混合颗粒的流化性能。 展开更多
关键词 DQMOM方法 聚合与破碎 纳米颗粒 多组分 微型流化床
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