一种安全协议的规范化设计方法     

邓帆  李益发  张文政 《武汉大学学报(信息科学版)》2010,(5)

提出了应用组合方法进行安全协议的规范化设计,给出了协议中基件与组件的定义,分析了组件的安全属性,及基于组件设计能实现相应安全目标的单步协议;定义了组合规则,确保不同的单步协议能够组合成为一个复合协议,同时各个单步协议还能实现各自的安全目标。至此,根据具体的应用背景选择合适的单步协议,按照组合规则组合后,便可得到满足需求的安全协议。该方法可将一个复杂协议分解为若干基于组件的简单单步协议,使得协议的设计与分析都易于实现。  相似文献   

基于改进反应位移法的盾构隧道横向抗震规律研究     

许有俊  车彦文  田治旺  崔广琴 《震灾防御技术》2017,12(3):613-624

在地震动作用下,小间距盾构隧道夹土层区域的动力反应影响结构的内力与变形,而反应位移法未考虑夹土层弹簧参数的变化,本文针对这一误差来源,提出了改进反应位移法。一方面在反应位移法合理内容的基础上完善计算模型,另一方面通过数值计算将改进反应位移法与动力时程法进行对比分析,并拟合理论模型对改进的方法进行修正。结果表明,两种算法下结构的地震响应规律一致;间距d≥8m时,结构地震动反应变化不明显,可按反应位移法计算;理论模型提高了改进反应位移法计算结果的精度。  相似文献   

非开挖水平定向钻进软件设计研究   总被引：1，自引：0，他引：1  

周从明  黄中权 《煤田地质与勘探》2005,33(1):76-78

轨迹设计是非开挖水平定向钻进管线铺设施工的关键。本文应用动态规划原理, 对轨迹最优化设计进行了深入研究。根据工程实际需要, 设计出一套水平定向钻进软件, 实现了轨迹最优化设计、施工图设计、竣工图处理、施工记录表填写及轨迹查询等功能, 集设计、优化、出图于一体。实践证明, 该软件能很好地满足水平定向钻进工程的要求。   相似文献   

Spatial and Temporal Variations in Earthquake Stress Drops between the 2008 Wenchuan and 2013 Lushan Earthquakes     

WU Weiwei  LONG Feng  LIANG Mingjian  WEI Yaling  SUN Wei  CHEN Xuefen  ZHAO Jing 《《地质学报》英文版》2020,94(5):1635-1650

As a case study of spatial and temporal variations in earthquake stress drops between the 2008 Ms 8.0 Wenchuan and 2013 Ms 7.0 Lushan earthquakes, we computed 1828 stress-drop values for earthquakes with magnitudes 1.7 ≤ ML ≤ 5.0 during an eight-year time span before and after major earthquakes. We divide the study area into three subregions (the southern segment of the Longmen Shan fault zone; the southwestern junction of the Longmen Shan and Sichuan Basin; and the southwestern margin of the Sichuan Basin) and calculate individual event stress drops in each. The results show that regions of alternating high and low stress drop are found on either side of the southwestern segment of the Longmen Shan fault zone. During the two-year period after the 2008 Ms 8.0 Wenchuan earthquake, the stress state of the southern Longmen Shan fault shows no significant change. A marked increase in stress level appears about 18 months before the 2013 Ms 7.0 Lushan earthquake near the Lushan hypocenter zone. Two months after the Ms 7.0 event, the stress drops suddenly attenuate, with significantly less seismic energy release per event. We find that changes in the patterns of high and low stress drop values are consistent with the process of stress accumulation or transfer from the pre-mainshock to post-mainshock periods. The results indicate that major earthquakes are the dominant cause of temporal and spatial evolution in stress levels. Stress drop variations show obvious temporal and spatial patterns that may suggests subtle changes in the character of stress fields on faults and spatial variations related to local intense compression and tectonic effects.  相似文献   

深海超长沉积物柱状取样系统关键技术优化及应用          下载免费PDF全文

张建兴  栾振东  卢新亮  连超  张鑫 《海洋科学进展》2023,41(1)

作为深海科学研究的重要基础装备,深海超长沉积物柱状取样系统在海底地形地貌、海洋地质构造、气候环境变化等研究领域发挥了重要作用,其在海底矿产资源勘探、海洋工程地质勘察等方面展现了巨大应用价值。针对传统超长柱状沉积物取样系统在作业过程中存在的盲目采样、安全隐患大、甲板作业空间受限等问题,自主研制了一套适用于深海的超长可控可视沉积物柱状取样系统,该系统具有液压锤击、立式收放和实时监控功能,能获取连续、超长、具有精准姿态方位信息的柱状沉积物样品。现通过对独立排缆方式、取样管快速拆装、样品封堵、低扰动取样刀头等关键技术细节进行优化,解决了样品扰动大、取样率低的问题,提高了取样作业效率与样品质量,且降低了作业安全风险。2017—2021年,该取样系统搭载不同母船在南海1 700,1 725 和1 778 m水深分别获取了15.25、16.01和15.83 m的长柱状沉积物样品。该设备的成熟应用,可为我国深海探测研究提供技术支持。  相似文献   

Late Pleistocene environmental information on the Diexi paleo-dammed lake of the upper Minjiang River in the eastern margin of the Tibetan Plateau,China     

WANG Lan-sheng  WANG Xiao-qun  SHEN Jun-hui  YIN Guan  CUI Jie  XU Xiang-ning  ZHANG Zhi-long  WAN Tao  WEN Li-wang 《山地科学学报》2020,17(5):1172-1187

In 1999, Diexi paleo-dammed lake(2349 m a.s.l.) was discovered around Diexi town along the Minjiang River in Sichuan province. Diexi is located where the eastern edge of the Tibetan Plateau and the Sichuan Basin meet. The dammed lake was formed during the Last Glacial Maximum of the Late Pleistocene(~30,000 years ago) and began to empty about 15,000 years ago. The lacustrine sediments(up to 240 m thick) preserve abundant paleoenvironment information. In this paper, a mass of oxygen isotopes and 14 C dating from drilled cores are analyzed and discussed. The δ18 O curve on the paleo climate from this section is comparable with the coeval paleo climatic curves of ice cores and karsts in China and others. Furthermore, the physical model testing has confirmed that the disturbed zones in the core are caused by strong earthquakes occurred at least 10 times, which implies strong crustal deformation, as an important driving force, affecting climate change. This study provides a new window to observe East Asian monsoon formation, paleoenvironmental evolution and the global climate change.  相似文献   

Columbitization of fluorcalciopyrochlore by hydrothermalism at the Saint-Honoré alkaline complex,Québec (Canada): New insights on halite in carbonatites     

《Ore Geology Reviews》2017

Niobium (Nb) in carbonatite is mainly hosted in fluorcalciopyrochlore and columbite-(Fe). Information related to Nb petrogenesis is useful for understanding the processes related to Nb mineralization and carbonatite evolution. The Saint-Honoré, Quebec, alkaline complex offers a rare opportunity for studying these processes as the complex is not affected by post-emplacement deformation, metamorphism nor weathering. Columbite-(Fe) is shown to be an alteration product of fluorcalciopyrochlore (columbitization). Columbitization is characterized by the leaching of Na and F from the A- and Y-sites of the pyrochlore crystal structure. As alteration increases, Fe and Mn are slowly introduced while Ca is simultaneously leached. Leached Ca and F then crystallize as inclusions of calcite and fluorite within the columbite-(Fe). A-site cations and vacancies in the crystal structure of fresh and altered pyrochlores demonstrate that pyrochlore alteration is hydrothermal in origin. Moreover, halite is a ubiquitous mineral in the Saint-Honoré alkaline complex. Petrographic evidence shows that halite forms in weakly altered pyrochlores, suggesting halite has a secondary origin. As alteration increases, halite is expelled by the hydrothermal fluid and is carried farther into the complex, filling factures throughout the carbonatite. The hydrothermal hypothesis is strengthened by significant enrichments in Cl and HREEs in columbite-(Fe). Chlorine is most likely introduced by a hydrothermal fluid that increases the solubility of REEs.  相似文献   

Manifestations and mechanisms of mountain glacier-related hazards     

Xin Wang  Qiao Liu  ShiYin Liu  GuangLi He 《寒旱区科学》2020,12(6):436-446

Mountain glacier-related hazards occur worldwide in response to increasing glacier instability and human activity intensity in modern glacierized regions. These hazards are characterized by their spatial aggregation and temporal repeatability. Comprehensive knowledge about mountain glacier-related hazards is critical for hazard assessment, mitigation, and prevention in the mountain cryosphere and downstream regions. This article systematically schematizes various mountain glacier-related hazards and analyzes their inherent associations with glacier changes. Besides, the processes, manifestations, and mechanisms of each of the glacier-related hazards are summarized. In the future, more extensive and detailed systematic surveys, for example, considering integrated ground-air-space patterns, should be undertaken for typical glacierized regions to enhance existing knowledge of such hazards. The use of coupled numerical models based on multi-source data is challenging but will be essential to improve our understanding of the complex chain of processes involved in thermal-hydrogeomorphic glacier-related hazards in the mountain cryosphere.  相似文献   

四川攀西地区铜矿主要类型、地质特征找矿标志与成矿预测   总被引：1，自引：0，他引：1  

覃瑜  周存中 《四川地质学报》2009,29(4):422-425

通过总结攀西地区铜矿主要成因类型及典型矿床成矿特征及找矿标志分析,根据各类型矿床成矿时代与分布,结合2007年四川省主要矿产成矿区带划分资料,对攀西地区Ⅳ、Ⅴ级成矿靶区进行了预测。  相似文献   

Improvement of surface albedo simulations over arid regions     

鲍艳  吕世华  张宇  孟宪红  杨胜朋 《大气科学进展》2008,25(3):481-488

To improve the simulation of the surface radiation budget and related thermal processes in arid regions, three sophisticated surface albedo schemes designed for such regions were incorporated into the Biosphere- Atmosphere Transfer Scheme （BATS）. Two of these schemes are functions of the solar zenith angle （SZA）, where the first one has one adjustable parameter defined as SZA1 scheme, and the second one has two empirical parameters defined as SZA2 scheme. The third albedo scheme is a function of solar angle and soil water that were developed based on arid-region observations from the Dunhuang field experiment （DHEX） （defined as DH scheme）. We evaluated the performance of the original and newly-incorporated albedo schemes within BATS using the in-situ data from the Oasis System Energy and Water Cycle Field Experiment that was carried out in JinTa, Gansu arid area （JTEX）. The results indicate that a control run by the original version of the BATS generates a constant albedo, while the SZA1 and SZA2 schemes basically can reproduce the observed diurnal cycle of surface albedo, although these two schemes still underestimate the albedo when SZA is high in the early morning and late afternoon, and overestimate it when SZA is low during noontime. The SZA2 scheme has a better overall performance than the SZA1 scheme. In addition, BATS with the DH scheme slightly improves the albedo simulation in magnitude as compared to that from the control run, but a diurnal cycle of albedo is not produced by this scheme. The SZA1 and SZA2 schemes significantly increase the surface absorbed solar radiation by nearly 70 W m^-2, which further raises the ground temperature by 6 K and the sensible heat flux by 35 W m^-2. The increased solar radiation, heat flux, and temperature are more consistent with the observations that those from the control run. However, a significant improvement in these three variables is not found in BATS with the DH scheme due to the neglect of the diurnal cycle of albedo. Further analysis indi  相似文献