中国晚新生代碱性玄武岩中贯穿双晶贵橄榄石

B80年代至今,在研究我国北方晚新生代碱性重武岩过程中,首先在内蒙的达里诺尔和黑龙江的科洛火山岩中观察到具贯穿双晶的贵橄榄石,最初认为是一种偶然现象。     

Paleostress fields from calcite twins in the Pyeongan Supergroup, South Korea

Abstract   Paleostress fields of the Late Paleozoic to Early Mesozoic Pyeongan Supergroup that is distributed along the northeastern part of the Ogcheon Belt in South Korea were investigated using the calcite strain gauge (CSG) technique. Combining the results of this study with those of other studies investigating the relationship between twin strain, twin density and width, which are used as indicators of deformation conditions in the natural low-temperature deformation of limestone, it was estimated that calcite twins in the study area were probably formed at temperatures lower than 170°C. From two samples, two different principal paleostress directions were inferred from calcite twins, while only one direction was inferred from two other samples. This result suggests that deformation occurred during two or more different tectonic events in the Pyeongan Supergroup during the Mesozoic era. The maximum shortening axis was oriented in two directions, northeast–southwest and northwest–southeast, respectively, which coincide well with the paleostress directions inferred from the stress inversion for many fault sets. Combining the results of the paleostress analysis from this and other studies, we hypothesize that the directions of the maximum shortening axis in the Pyeongan Supergroup changed from northeast–southwest during the pre-Daebo orogeny period (Late Triassic period) to northwest–southeast during the syn-Daebo orogeny period (Early Jurassic to Early Cretaceous period) in the Mesozoic era.     

一种反条纹长石的形成机制及其冷却史

对承德黑山苏长岩中反条纹长石进行显微镜研究表明,钾长石条纹具乳滴状和细脉状两种形式。前者在成核后的生长中,或多或少趋向等轴状,是一种非共格的离溶作用,而后者对主晶有确定的取向。在透射电镜下,此类条纹与其主晶界面的应变能,说明它是半共格离溶的。斜长石主晶是‘e斜长石’组成的两相交生体,即所谓Bφggild交生。本文还讨论了它的冷却史及由它表明的地质环境。     

复式钢管混凝土外肋环板节点抗剪承载力研究

在已有理论和试验研究的基础上,对复式钢管混凝土外肋环板节点的抗剪受力性能进行分析。建立了节点核心区的抗剪受力模型,将节点域抗剪贡献分为三部分:节点域内外钢管腹板的抗剪贡献、节点主要连接件竖向肋板与锚固腹板的抗剪贡献以及节点域混凝土的抗剪贡献,推导了复式钢管混凝土柱节点屈服抗剪承载力和极限抗剪承载力的计算公式,为复式钢管混凝土柱节点的工程设计提供承载力计算方法。理论得到的节点屈服剪力和极限剪力值与试验结果进行了对比,并提出抗剪能力储备系数这一新指标反映节点的抗剪切破坏能力,量化地解释了节点发生梁铰破坏后抗剪能力的安全储备。得出此类新型节点在破坏时抗剪储备能力充足,可保证节点达到良好延性的破坏模式,说明节点设计符合强剪弱弯的抗震设计原则。     

新型双船起重拆除平台试验研究

拆除大型海上结构物是一项非常复杂且充满挑战的工程。现提出一种新型海上平台拆除方案,该方案利用三条半潜船来代替具有重型起重装置的单一船舶,通过两艘相同的半潜船将平台上层建筑托起,随后运至第三艘半潜船上完成平台拆除。在风浪流作用下,半潜船和平台的所处方位和运动姿态一直处于动态变化中,这对船舶调节压载的稳定性以及双船运动的同步性提出了要求。为了确保该方案的高效性和安全性,设计了一套完整的模型试验装置,包括船舶模型、平台拆卸辅助设备、六自由度运动采集与分析系统、控制系统、无线通讯系统以及测量系统。开展了相应的水池试验,试验结果验证了双船起重拆除平台方案中双船协同运输这一关键环节的可行性和安全性。     

基于准连续介质方法模拟纳米多晶体Ni中裂纹的扩展

通过准连续介质方法模拟了纳米多晶体Ni中裂纹的扩展过程.模拟结果显示:裂纹尖端的应力场可以导致晶界分解、层错和变形孪晶的形成等塑性形变;在距离裂纹尖端越远的位置,变形孪晶越少;在裂纹尖端附近相同距离处,层错要远多于变形孪晶.这反映了局部应力的变化以及广义平面层错能对变形孪晶的影响.计算了裂纹尖端附近区域原子级局部静水应力的分布.计算结果表明:裂纹前端晶界处容易产生细微空洞,这些空洞附近为张应力集中区,并可能促使裂纹沿着晶界扩展.模拟结果定性地反映了纳米多晶体Ni中的裂纹扩展过程,并与相关实验结果符合得很好     

拉压性能不同材料圆环极限压力分析及应用

应用双剪应力强度理论对拉压异性材料制成的圆环进行了弹塑性应力分析, 得到了弹性极限内压力、弹塑性极限内压力与拉压比的关系式, 并举例说明了其在岩土材料抗拉强度测试中的应用。     

顾及地面POS信息的空地一体城市三维实景重建

实景三维模型为数字孪生提供了统一的数字空间底座。在城市场景中,贴近地面及在空中视角下被遮挡的地物是实景三维重建的难点。针对城市复杂空间环境和无人机飞行局限的问题,本文基于倾斜摄影与空地一体融合建模的基础理论,考虑POS信息对空地一体空三融合的影响,提出了一种顾及地面POS信息的城市实景三维重建方法,并使用此方法对佛山市历史文化街区进行了精细化建模。试验表明,与常规方法相比,该方法的模型效果好、效率高,对实景三维产品的生产与空间数据多尺度表达具有重要意义,可为数字孪生应用提供更精细的地理场景表现形式。     

智慧城市建设中的数字孪生与元宇宙探讨

随着城市管理和空间大数据、5G、人工智能等新型技术的深入结合,新型智慧城市相关的应用成为地理信息行业领域与社会重点关注的对象。本文主要介绍了智慧城市的背景与概念、理论与技术,阐述了数字城市、智慧城市及数字孪生城市三者的关系,总结了数字孪生城市现状及趋势,并探讨了元宇宙时代的智慧城市。智慧城市的萌芽期依靠空间信息技术、数据库技术、虚拟现实技术及计算机网络技术等构建数字城市,发展期在数字城市基础上融合人工智能技术、物联网技术、云技术及时空大数据技术等建设新型智慧城市,建设期结合新型智慧城市相关技术和实景三维技术等实现数字孪生。展望了跨时代的元宇宙智慧城市,或许会在数字孪生的基础上融合增强现实、扩展现实、脑机接口与体感设备等技术或设备,实现人类生活在两栖世界的美好憧憬。     

Paleostress reconstruction from calcite twin and fault–slip data using the multiple inverse method in the East Walanae fault zone: Implications for the Neogene contraction in South Sulawesi,Indonesia

A new approach for paleostress analysis using the multiple inverse method with calcite twin data including untwinned e-plane was performed in the East Walanae fault (EWF) zone in South Sulawesi, Indonesia. Application of untwinned e-plane data of calcite grain to constrain paleostress determination is the first attempt for this method. Stress states caused by the collision of the south-east margin of Sundaland with the Australian microcontinents during the Pliocene were successfully detected from a combination of calcite-twin data and fault–slip data. This Pliocene NE–SW-to-E–W-directed maximum compression activated the EWF as a reverse fault with a dextral component of slip with pervasive development of secondary structures in the narrow zone between Bone Mountain and Walanae Depression.