深井密封容器的耐压计算     

李翠霞  蔡庆福  李树德 《大地测量与地球动力学》2007,27(Z1):119-121

运用经典和近代材料力学的理论对深井密封容器的耐压性能进行计算，根据计算结果及相关材料的特性，对科研课题所需的材料进行初步筛选，给出一定安全系数下容器的最小壁厚。  相似文献   

利用泥芯示踪九连墩楚墓青铜器的产地          下载免费PDF全文

魏国锋  秦颍  姚政权  王昌燧  胡雅丽  黄凤春 《岩石矿物学杂志》2011,30(4):701-715

探讨了利用青铜器内残留的陶范或泥芯示踪青铜器产地的可行性。采用偏光显微镜、XRD、XRF、NAA等技术手段,测试分析了湖北九连墩楚墓青铜器内的泥芯,发现九连墩外来风格青铜器的泥芯,在物相、微观结构、化学成分、植硅体组合等方面与本地风格青铜器的泥芯有较大差异。外来风格青铜器的泥芯,其CaO含量很高,达6%以上,而Na2O的含量相对较低,这一富钙、贫钠的特点,与中国黄土的典型特征极为吻合。结合泥芯中的植硅体组合特征,推测九连墩外来风格的青铜器很可能来自中国北方黄土堆积地区,系当地铸造后输入到楚国的。本研究表明利用青铜器内的泥芯或陶范残留,可望有效地示踪青铜器的产地。  相似文献   

一种智能化的避台航线设计方法     

汤青慧  陈戈  刘艳艳 《中国海洋大学学报(自然科学版)》2011,41(6):104-108

为提高船舶气象导航自动化水平,实现避台决策由经验型向智能型转变,提出1种高效、稳定的绕避台风航线规划算法。基于电子海图平台实现GPS、数字化气象信息的多源信息集成,直观显示船舶和台风当前位置和运动态势,基于栅格模型设计避台航线自动生成算法,实现避台航线在线实时规划。仿真结果表明,该方法能够根据气象信息及时重建环境模型并获取新的最优航线,算法对环境的复杂性不敏感,具有稳定性好、求解规模大、效率高的特点。  相似文献   

Xylem anatomy and hydraulic conductivity of three co-occurring desert phreatophytes     

A. RzepeckiF. Zeng  F.M. Thomas 《Journal of Arid Environments》2011,75(4):338-345

The tree species Populus euphratica, the shrub Tamarix ramosissima and the sub-shrub Alhagi sparsifolia are phreatophytes that grow along the southern fringe of the Taklamakan Desert (NW China). We hypothesised that in the shoot xylem of these species, the fraction of conduits with a large cross-sectional area and the hydraulic conductivity decrease in the sequence A. sparsifolia > T. ramosissima > P. euphratica according to the different ground water distances at the typical sites of the species’ occurrence. The theoretical hydraulic conductivity related to the total cross-sectional xylem area (k_ttot) or to the cross-sectional area of the conduits (k_tcond) was computed using a modified Hagen-Poiseuille equation. The percentage of wide conduits and k_tcond were highest in A. sparsifolia, and smallest, in P. euphratica. With regard to k_ttot, the diffuse-porous to semi-ring-porous P. euphratica occupied an intermediate position due to an increased percentage of conducting area related to the total cross-sectional xylem area. This figure as well as k_ttot were lowest in the semi-ring-porous to ring-porous T. ramosissima. The k_ttot values corresponded to the leaf area-related hydraulic conductivity calculated from measurements in the field. Altogether, our results match the typical occurrence of the species with respect to the ground water depth.  相似文献   

Semi‐explicit rate‐dependent modeling of damage‐avoidance steel connections using HF2V damping devices     

Geoffrey W. Rodgers  J. Geoffrey Chase 《地震工程与结构动力学》2011,40(9):977-992

A rate‐dependent modeling technique is developed for moment resisting steel connections that utilize non‐linear viscous dampers. First, a model of the Maxwell‐type is developed that considers the non‐linear viscous damper and connection flexibility for translational motion. This model is compared with experimental results at several input motion frequencies to validate the results. The model is then extended to represent an exterior steel beam‐to‐column connection using damage‐avoidance design and non‐linear viscous dampers. By including terms to represent structural member and connection flexibility, using appropriate geometric transformations the model can be formulated to give the overall lateral load‐drift structural performance. Validation analysis shows good agreement between experimental observations and the model predictions. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

船只目标SAR、HFSWR和AIS多手段融合探测的点迹关联分析   总被引：3，自引：1，他引：2  

纪永刚  张杰  孟俊敏  王祎鸣 《海洋学报(英文版)》2014,33(9):73-81

A space-borne synthetic aperture radar （SAR）, a high frequency surface wave radar （HFSWR）, and a ship automatic identification system （AIS） are the main remote sensors for vessel monitoring in a wide range. These three sensors have their own advantages and weaknesses, and they can complement each other in some situations. So it would improve the capability of vessel target detection to use multiple sensors including SAR, HFSWR, and A/S to identify non-cooperative vessel targets from the fusion results. During the fusion process of multiple sensors＇ detection results, point association is one of the key steps, and it can affect the accuracy of the data fusion and the efficiency of a non-cooperative target＇s recognition. This study investigated the point association analyses of vessel target detection under different conditions： space- borne SAR paired with AIS, as well as HFSWR, paired with AIS, and the characteristics of the SAR and the HFSWR and their capability of vessel target detection. Then a point association method of multiple sensors was proposed. Finally, the thresholds selection of key parameters in the points association （including range threshold, radial velocity threshold, and azimuth threshold） were investigated, and their influences on final association results were analyzed.  相似文献   

平台运动下悬垂立管动力响应及疲劳损伤特性试验研究   总被引：1，自引：0，他引：1  

吴天昊  付世晓  张智奇  何玥 《海洋工程》2018,36(3):18-25

悬垂立管因其经济性被广泛应用在深海油气开发中。悬垂立管在顶端平台运动作用下,会不断产生横流向以及顺流向动力响应,循环累积造成疲劳损伤。为了研究悬垂立管在平台运动作用下的疲劳损伤特性,开展了大尺度悬垂立管模型试验。采用小波分析、模态分析、雨流计数法等方法处理分析试验数据。分析平台运动下无内流作用下大尺度悬垂立管动力响应及疲劳损伤特性,发现横流向弯曲应变结果较为复杂,局部呈现行波特性,主导频率具有时变性。相比之下,顺流向弯曲应变结果比较有规律性,整体呈现行波特性,主导频率不具有时变性,并始终保持与顶端平台运动频率相同。平台运动引发的悬垂立管涡激振动疲劳损伤和KC数有关。各点面内疲劳损伤值延管长分布趋势和面内应变RMS延管长分布趋势相似。横流向(CF方向)的疲劳损伤的数量级为顺流向(IL方向)的10-2倍左右。  相似文献   

Stress analysis of top tensioned riser under random waves and vessel motions     

Xiaomin Li  Haiyan Guo  Fanshun Meng 《中国海洋大学学报(英文版)》2010,9(3):251-256

The bending stresses of top tensioned riser(TTR)under combined excitations of currents, random waves and vessel motions are presented in this paper, and the effect of the internal flowing fluid on the riser stresses is also considered. The computation programs which are used to solve the differential equations in the time domain are compiled and the principal factors of concern including the angular movements at the upper and lower ends of the riser, lateral displacements and bending stresses are presented. Then the effects of current velocity, random wave, top tension, vessel mean offset, low frequency motion and internal flow velocity on the bending stresses of the riser are analyzed in detail.  相似文献   

Dynamic responses of top tensioned riser under combined excitation of internal solitary wave, surface wave and vessel motion     

GUO Haiyan  ZHANG Li  LI Xiaomin  LOU Min 《中国海洋大学学报(英文版)》2013,12(1):6-12

An investigation on the dynamic response of a top tensioned riser (TTR) under combined excitation of internal solitary wave, surface wave and vessel motion is presented in this paper. The riser is idealized as a tensioned slender beam with dynamic boundary conditions. The KdV-mKdV equation is chosen to simulate the internal solitary wave, and the vessel motion is analysed by using the method proposed by Sexton. Using finite element method, the governing equation is solved in time domain with Newmark-β method. The computation programs for solving the differential equations in time domain are compiled and numerical results are obtained, including dimensionless displacement and stress. The action of internal solitary wave on the riser is like a slow powerful impact, and is much larger than those of surface wave and vessel motion. When the riser is under combined excitation, it vibrates at frequencies of both surface wave and vessel motion, and the vibration is dominated by internal solitary wave. As the internal solitary wave crest passes by the centre of the riser, the maximum displacement and stress along the riser occur. Compared to the lower part, the displacement and stress of the riser in the upper part are much larger.  相似文献   

Experimental testing of a rocking timber shear wall with slip‐friction connectors          下载免费PDF全文

Wei Y. Loo  Chern Kun  Pierre Quenneville  Nawawi Chouw 《地震工程与结构动力学》2014,43(11):1621-1639

Allowing a structure to uplift and rock during an earthquake is one way in which activated forces can be capped and damage to the structure avoided or minimised. Slip‐friction connectors (also known as slotted‐bolt connectors) were originally developed for use in steel construction, but for this research have been adapted for use as hold‐downs in an experimental 2.4 m × 2.4 m rigid timber shear wall. A novel approach is used to achieve the desired sliding threshold in the connectors, and the wall uplifts when this threshold is reached. From a series of quasi‐static cyclic tests, it is shown that slip‐friction connectors can impart ductile and elasto‐plastic characteristics to what would otherwise be essentially brittle structures. Because forces on the wall were capped by the slip‐friction connectors to levels well below the design level, no damage to the wall was observed. Self‐centring potential was also found to be excellent. The slip‐friction connectors themselves are of a unique design and have proven to be robust and durable, adequately performing their duty even after almost 14 m of cumulative travel under high contact pressures. To resist base shear without unduly affecting rocking behaviour, a new type of shear‐key is proposed and implemented, and a procedure developed to quantify its influence on overall wall behaviour. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献