Results 31 to 40 of about 407,494 (154)

不同连接形式的钢管混凝土节点抗连续倒塌与抗震综合能力分析

open access: yesJianzhu Gangjiegou Jinzhan, 2022
为研究钢管混凝土结构抗连续倒塌与抗震综合防御能力,采用有限元软件ABAQUS建立了6个不同连接形式的钢管混凝土节点有限元模型,在合理选取钢材和混凝土材料本构模型的基础上,对比分析竖向荷载作用下各节点抗连续倒塌破坏特征,获得各类节点的抗倒塌承载力和破坏特征。在此基础上,计算各节点在水平低周往复荷载作用下的滞回性能,获得其承载力曲线、刚度退化、延性、耗能能力等抗震性能指标。研究结果表明:竖向荷载作用下,栓焊混合外环板式和内隔板式节点的抗连续倒塌能力较好;水平往复荷载作用下 ...
王景玄, 王文琦
doaj  

Fabrication‐Driven Oxidation Pathways in Y/Hf‐Modified High‐Entropy Alloys: From Elemental Segregation to Oxide Homogeneity

open access: yesRare Metals, Volume 45, Issue 2, February 2026.
ABSTRACT This study elucidates the oxidation mechanisms governing Y/Hf‐doped AlCoCrFeNiTi high‐entropy alloys (HEAs) and reveals the pivotal role of fabrication processes in dictating high‐temperature oxidation behavior. We demonstrate that casting and spark plasma sintering (SPS) promote Y/Hf segregation, resulting in heterogeneous oxide formation and
Huaqing Yi   +5 more
wiley   +1 more source

速度管柱带压起管技术研究与管材性能评价

open access: yesShiyou jixie, 2015
连续管速度管柱是油田排水采气的主体技术之一,连续管使用一定年限后需要起出,而国内速度管柱带压起管技术尚属空白。鉴于此,研制了φ38.1 mm速度管柱起管所需的管塞和滚压式重载连接器等关键工具。通过室内试验验证了关键工具结构的可行性,并在苏里格气田成功实施2口井的带压起管现场作业,最后对起出的连续管进行性能评价。室内试验和现场应用结果表明,该速度管柱带压起管技术解决了速度管柱管内封堵和上提解卡的核心问题,满足现场带压起管作业要求。
周忠城   +6 more
doaj  

Giant Tunability of Individual Magnetic Skyrmion Size via an Oscillating Local Magnetic Field

open access: yesRare Metals, Volume 45, Issue 2, February 2026.
ABSTRACT Magnetic skyrmions hold great promise as memory and computing elements in future spintronic devices. Despite the demonstration of various devices, techniques for addressable and high‐precision manipulation of individual skyrmions remain scarce.
Cai‐Hong Xie   +13 more
wiley   +1 more source

连续管钻井系统摩阻计算方法与试验研究

open access: yesShiyou jixie, 2015
连续管应用越来越广泛,但是由于连续管管径小、流阻大等特点,系统性地研究连续管钻井系统摩阻压降已迫在眉睫。基于理论研究,筛选相关计算模型,得到了符合连续管钻井实际的摩阻计算模型;筛选了4种数值模拟计算模型,并进行多盘管规格和多流量的数值模拟计算,通过分析计算结果与理论计算的误差,采用标准κepsilon模型作为数值模拟计算模型更为合适。开展了连续管钻井系统盘管摩阻压降试验,将理论计算、数值模拟计算与试验数据进行比较,在绝大多数试验流量测点处,它们的误差范围均在10%以下 ...
周博   +5 more
doaj  

CHINA’S LAND FINANCE AS ACTIVE MODE OF LAND DEVELOPMENT AND INFRASTRUCTURE DELIVERY: Reality, History and Prospects

open access: yesInternational Journal of Urban and Regional Research, Volume 50, Issue 1, Page 191-220, January 2026.
Abstract Henry George advocated for capturing land value increases for public ends. The active approach of public authorities organizing and financing land development can help capture higher land value increases, as Hartman and Spit indicate. However, this approach hardly happens in developing countries, where the coalition of private developers and ...
Nannan Xu
wiley   +1 more source

连续管水平井钻磨作业力学分析

open access: yesShiyou jixie, 2014
连续管在水平井钻磨作业时,易发生屈曲变形而使轴向力传递效率降低,严重时可能由于轴向力降为0而发生自锁。在充分考虑屈曲、摩擦、弯矩、内外液体阻力等因素的影响下,建立了连续管在水平井钻磨作业过程中的力学模型,并分别推导出直段和弯曲段有效轴向力、接触力和摩阻力的数学模型。由所得的理论模型计算可知,连续管失稳屈曲类型主要是螺旋屈曲;改变连续管初始端的注入力大小对最大注入深度和增加钻压几乎没有影响,而不同管柱尺寸对等效轴向力分布影响很大。研究结果对连续管现场作业有借鉴意义。
张仕民   +5 more
doaj  

Continuities in policy change: The case of squatter housing redevelopment strategies in Türkiye

open access: yesReview of Policy Research, Volume 43, Issue 1, January 2026.
Abstract The introduction of the neoliberal agenda in the 1980s marked a milestone for urban studies, where the neoliberal framework became widely accepted as both given and explanatory for understanding urban phenomena. This tendency often obscured policy continuities rooted in the historical and social contexts of specific geographies.
Fatma Süphan Somalı, Ufuk Poyraz
wiley   +1 more source

一种连续流动超极化氙气体发生及样品原位处理装置

open access: yes, 2007
一种连续流动超极化氙气体发生及样品原位处理装置,其特征在于,由碱金属蒸发器和激光泵浦室组成;其中,碱金属蒸发器为一内部放置有碱金属的石英密封管,该石英密封管的一端连接样品处理气体阀,另一端连接一激光泵浦室;该激光泵浦室为一石英密封管,其一端通过一冷凝管连接至核磁共振仪的核磁探头;石英密封管外部套设一加热套,该加热套与温控仪连接;激光泵浦室与一激光器相连接。本实用新型提供的连续流动超极化氙气体发生及样品原位处理装置,适于催化材料孔结构与催化过程研究,利用激光泵浦超极化氙技术 ...
包信和   +4 more
core  

连续介质力学与断裂

open access: yes, 1982
在这篇文章里,我们结合断裂问题回顾连续介质办学的发展,并指出,为了更深地理解和描述断裂现象,还需要进一步完善连续介质力学。 一、经典弹塑性理论应用于断裂时的局限性和Grifith的理论 现讨论一维应变条件下裂纹的扩展问题。我们假设 1.材料是均匀的,就是说,所讨论的材料是没有内部结构的; 2.材料是弹性的 ...
郑哲敏
core   +2 more sources

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