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薄壁管壳体环矢挤压缩径工艺仿真分析与研究 被引量:2
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作者 王小芳 詹劲 +1 位作者 左小艳 李红军 《精密成形工程》 北大核心 2023年第7期229-236,共8页
目的针对空心薄壁件在缩径成形工序中力学性质难以观测且缩径成形加工效率较低的问题,提出一种使用18瓣环矢挤压模具进行环矢挤压一次性成形的缩径工艺,并研究了该工艺下薄壁管壳体的弹塑性变形规律。方法以外径6.3 mm、壁厚2 mm、颈缩... 目的针对空心薄壁件在缩径成形工序中力学性质难以观测且缩径成形加工效率较低的问题,提出一种使用18瓣环矢挤压模具进行环矢挤压一次性成形的缩径工艺,并研究了该工艺下薄壁管壳体的弹塑性变形规律。方法以外径6.3 mm、壁厚2 mm、颈缩宽度1 mm的小尺寸薄壁管壳体(Q255材料)为研究对象,基于Barlat'96屈服准则和M-K沟槽理论,结合L.H.Donnell理论,建立管壳体环矢挤压缩径的塑性微元应力模型,通过ANSYS软件建立环矢挤压缩径工艺有限元模型,并进行数值模拟分析,获得管壳体环矢挤压过程中内壁面和颈缩区厚度方向的应力分布规律;最后进行实验验证,利用千分尺测量外径,采用应力测定仪测量中心位点应力,验证了该工艺下仿真结果的准确性。结论颈缩区域宽径比越大,缩径成形越远离弹性区;内壁面的应力整体呈凸状分布;卸载后,壁厚方向的残余应力呈从外壁到内壁逐渐增大的线性分布趋势,缩径区中心点最大残余等效应力为319.76 MPa,分布在挤压部位的内表面;经实验验证,内壁面中心位点的最大残余应力为183 MPa,其与仿真分析结果(202.5 MPa)的吻合度高达91.5%,验证了仿真结果的准确性。该环矢挤压模具能够有效进行空心薄壁管壳体的一次性缩径成形,提高制造效率,该研究结果可为薄壁管件环矢挤压缩径成形的工艺设计及工程应用提供参考。 展开更多
关键词 薄壁管壳体 挤压 缩径成形 弹塑性变形 应力分布
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工业雷管薄壁壳环矢缩径力学性质模型研究
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作者 李红军 王小芳 +2 位作者 李巧敏 陈伟 左颖 《火工品》 CAS CSCD 北大核心 2023年第3期51-56,共6页
为研究工业雷管薄壁壳环矢挤压缩径成形工艺的力学性质,采用微元法结合弹塑性理论对环矢缩径成形工艺力学性质进行理论分析,并建立工业雷管薄壁壳环矢缩径有限元模型,利用ANSYS软件对缩径成形过程进行数值模拟,探究了管壳缩径成形的应... 为研究工业雷管薄壁壳环矢挤压缩径成形工艺的力学性质,采用微元法结合弹塑性理论对环矢缩径成形工艺力学性质进行理论分析,并建立工业雷管薄壁壳环矢缩径有限元模型,利用ANSYS软件对缩径成形过程进行数值模拟,探究了管壳缩径成形的应力应变分布规律,并通过试验对仿真模型的准确性进行了验证。结果表明:薄壁壳变形区最大等效应力出现在模具锥角与管壳接触的边线处;成形区的应力应变沿中心截面对称分布,随着位移进给量增加,应力应变沿纵截面线呈缓-快-缓的趋势增大,沿横截面线呈先减小再增大分布,内壁的最大应力及最大应变均略大于外壁。 展开更多
关键词 工业雷管 缩径成形 数值模拟 应力应变分布
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Prognositic value of anoikis and tumor immune microenvironment-related gene in the treatment of osteosarcoma
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作者 WANG Dong DENG Qing +7 位作者 PENG Yi TONG Zhaochen LI Zixin HUANG Liping ZENG Jin LI Jinsong MIAO Jinglei CHEN Shijie 《中南大学学报(医学版)》 CAS CSCD 北大核心 2024年第5期758-774,共17页
Objective:Osteosarcoma is a highly aggressive primary malignant bone tumor commonly seen in children and adolescents,with a poor prognosis.Anchorage-dependent cell death(anoikis)has been proven to be indispensable in ... Objective:Osteosarcoma is a highly aggressive primary malignant bone tumor commonly seen in children and adolescents,with a poor prognosis.Anchorage-dependent cell death(anoikis)has been proven to be indispensable in tumor metastasis,regulating the migration and adhesion of tumor cells at the primary site.However,as a type of programmed cell death,anoikis is rarely studied in osteosarcoma,especially in the tumor immune microenvironment.This study aims to clarify prognostic value of anoikis and tumor immune microenvironment-related gene in the treatment of osteosarcoma.Methods:Anoikis-related genes(ANRGs)were obtained from GeneCards.Clinical information and ANRGs expression profiles of osteosarcoma patients were sourced from the therapeutically applicable research to generate effective therapies and Gene Expression Omnibus(GEO)databases.ANRGs highly associated with tumor immune microenvironment were identified by the estimate package and the weighted gene coexpression network analysis(WGCNA)algorithm.Machine learning algorithms were performed to construct long-term survival predictive strategy,each sample was divided into high-risk and low-risk subgroups,which was further verified in the GEO cohort.Finally,based on single-cell RNA-seq from the GEO database,analysis was done on the function of signature genes in the osteosarcoma tumor microenvironment.Results:A total of 51 hub ANRGs closely associated with the tumor microenvironment were identified,from which 3 genes(MERTK,BNIP3,S100A8)were selected to construct the prognostic model.Significant differences in immune cell activation and immune-related signaling pathways were observed between the high-risk and low-risk groups based on tumor microenvironment analysis(all P<0.05).Additionally,characteristic genes within the osteosarcoma microenvironment were identified in regulation of intercellular crosstalk through the GAS6-MERTK signaling pathway.Conclusion:The prognostic model based on ANRGs and tumor microenvironment demonstrate good predictive power and provide more personalized treatment options for patients with osteosarcoma. 展开更多
关键词 ANOIKIS tumor immune microenvironment BIOINFORMATICS PROGNOSIS OSTEOSARCOMA
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保持细节特性的局部误差渐进网格简化算法 被引量:8
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作者 黄佳 温佩芝 +1 位作者 李丽芳 朱立坤 《计算机应用》 CSCD 北大核心 2016年第6期1704-1708,共5页
针对三维模型简化过程中生成渐进网格时存在局部区域精度与效率平衡优化的问题,提出一种基于局部区域环间法矢夹角变化的半边折叠渐进网格简化算法.首先,获取三维数据点的一环邻近点构成的邻域局部区域受重心度量距离约束的法矢,再获取... 针对三维模型简化过程中生成渐进网格时存在局部区域精度与效率平衡优化的问题,提出一种基于局部区域环间法矢夹角变化的半边折叠渐进网格简化算法.首先,获取三维数据点的一环邻近点构成的邻域局部区域受重心度量距离约束的法矢,再获取与一环邻域三角形集合点有交集的三角形集合作为二环邻域区域;然后,以这两个局部区域法矢点乘的值为边折叠的折叠代价,该值越小表示该区域越趋向于平面,应优先简化,否则予以保留;最后,采用三角形内角判断方法来保证简化后网格中三角形的正则度,以减小变形引起的误差.实验结果表明,所提算法在三维模型渐进网格简化中局部细节特性保持和效率上得到较好的平衡,能够满足实际应用的需要. 展开更多
关键词 渐进网格 间法 重心约束 细节保持 正则度
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浅谈几何教学中交错图形的思维问题
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作者 蒋志娴 《数学教学通讯(教师阅读)》 1990年第5期7-9,共3页
几何学是研究几何图形性质的一门科学,对几何图形的感知和分析能力是解几何题的关键。而几何图形往往是由基本几何图形交错而成,由于图形交错使几何概念的本质特征更为隐蔽,所以学生遇到这样的图形时往往产生错觉。
关键词 几何教学 思维问题 全等三角形 角边角公理 对应边 直观教具 公共边 彩色粉笔 感觉困难 矢环
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在探索中求完善
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《湖南教育(上旬)(A)》 1990年第12期28-28,共1页
自本刊第七期发表《这样的作文试题行吗》一文后,又一次引起了热烈的争议。争议集中在作文试题的形式上。作文命题形式走向多样化,这是语文教学改革的发展趋向。这道五年级作文试题的出题者。
关键词 作文命题 语文教学改革 五年级 出题者 七期 矢环 囊囊 性解 触发点
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Solution of Klein-Gordon Equation for Pseudo-Coulomb Potential Plus a New Ring-Shaped Potential
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作者 肖勇军 隆正文 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第1期54-56,共3页
Under the condition of an equal mixing of vector and scalar potentials, exact solutions of bound states of theKlein-Gordon equation with pseudo-Coulomb potential plus a new ring-shaped potential are presented. Simulta... Under the condition of an equal mixing of vector and scalar potentials, exact solutions of bound states of theKlein-Gordon equation with pseudo-Coulomb potential plus a new ring-shaped potential are presented. Simultaneously,energy spectrum equations are also obtained. It is shown that the radial equation and angular wave functions areexpressed by confluent hypergeogetric and hypergeogetric functions respectively. 展开更多
关键词 Pseudo-Coulomb potential plus a new ring-shaped potential bound states exact solution
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Collision avoidance planning in multi-robot system based on improved artificial potential field and rules 被引量:4
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作者 原新 朱齐丹 严勇杰 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第3期413-418,共6页
For real-time and distributed features of multi-robot system,the strategy of combining the improved artificial potential field method and the rules based on priority is proposed to study the collision avoidance planni... For real-time and distributed features of multi-robot system,the strategy of combining the improved artificial potential field method and the rules based on priority is proposed to study the collision avoidance planning in multi-robot systems. The improved artificial potential field based on simulated annealing algorithm satisfactorily overcomes the drawbacks of traditional artificial potential field method,so that robots can find a local collision-free path in the complex environment. According to the movement vector trail of robots,collisions between robots can be detected,thereby the collision avoidance rules can be obtained. Coordination between robots by the priority based rules improves the real-time property of multi-robot system. The combination of these two methods can help a robot to find a collision-free path from a starting point to the goal quickly in an environment with many obstacles. The feasibility of the proposed method is validated in the VC-based simulated environment. 展开更多
关键词 artificial potential field simulated annealing avoiding rules collision avoidance planning multirobots
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