基于ANSYS和响应面法的抗滑桩结构可靠性分析

在深入分析可靠度指标的几何意义和响应面法的基本思想的基础上,提出了基于ANSYS和响应面法的可靠度算法与步骤。分析了陕西省吴起县大路沟巨型黄土滑坡的工程地质条件,根据滑坡的工程地质勘察资料和滑坡治理工程的设计资料,建立了基于ANSYS的抗滑桩桩土体系有限元模型,经过自重作用下桩土结构有限元分析,验证了该有限元模型的有效性。在此基础上,选取滑体土重度、滑面土内聚力c和内摩擦角、滑面以下土的压缩模量Es;4个随机变量,基于响应面(中心复合设计CCD)法和通用有限元软件ANSYS平台,建立了抗滑桩的可靠度分析模型,并研制了对应算法。工程算例结果表明:当试验点数量N=25时,抗滑桩结构的失效概率Pf=0.35%,可靠度指标=2.70,从而验证了基于ANSYS和CCD响应面法建立抗滑桩可靠度计算模型及算法是可行的。     

Al-Cu-Fe alloys in the solar system: Going inside a Khatyrka-like micrometeorite (KT01) from the Nubian Desert,Sudan

A recently described micrometeorite from the Nubian desert (Sudan) contains an exotic Al-Cu-Fe assemblage closely resembling that observed in the Khatyrka chondrite (Suttle et al., 2019; Science Reports 9:12426). We here extend previous investigations of the geochemical, mineralogical, and petrographic characteristics of the Sudan spherule by measuring oxygen isotope ratios in the silicate components and by nano-scale transmission electron microscopy study of a focused ion beam foil that samples the contact between Al-Cu alloys and silicates. O-isotope work indicates an affinity to either OC or CR chondrites, while ruling out a CO or CM precursor. When combined with petrographic evidence we conclude that a CR chondrite parentage is the most likely origin for this micrometeorite. SEM and TEM studies reveal that the Al-Cu alloys mainly consist of Al metal, stolperite (CuAl), and khatyrkite (CuAl₂) together with inclusions in stolperite of a new nanometric, still unknown Al-Cu phase with a likely nominal Cu₃Al₂ stoichiometry. At the interface between the alloy assemblage and the surrounding silicate, there is a thin layer (200 nm) of almost pure MgAl₂O₄ spinel along with well-defined and almost perfectly spherical metallic droplets, predominantly iron in composition. The study yields additional evidence that Al-Cu alloys, the likely precursors to quasicrystals in Khatyrka, occur naturally. Moreover, it implies the existence of multiple pathways leading to the association in reduced form of these two elements, one highly lithophile and the other strongly chalcophile.     

Preparation,Characterization and Pharmacokinetics of Fluorescence Labeled Propylene Glycol Alginate Sodium Sulfate

A rapid and sensitive fluorescence labeling method was developed and validated for the microanalysis of a sulfated polysaccharide drug,namely propylene glycol alginate sodium sulfate （PSS）,in rat plasma.Fluorescein isothiocyanate （FITC） was selected to label PSS,and 1,6-diaminohexane was used to link PSS and FITC in order to prepare FITC-labeled PSS （F-PSS） through a reductive amination reaction.F-PSS was identified by UV-Vis,FT-IR and ^1H-NMR spectrum.The cell stability and cytotoxicity of F-PSS were tested in Madin-Darby canine kidney （MDCK） cells.The results indicated that the labeling efficiency of F-PSS was 0.522%±0.0248% and the absolute bioavailability was 8.39%.F-PSS was stable in MDCK cells without obvious cytotoxicity.The method was sensitive and reliable; it showed a good linearity,precision,recovery and stability.The FITC labeling method can be applied to investigating the absorption and metabolism of PSS and other polysaccharides in biological samples.     

白冠破碎空间分布模式的统计推断

白冠空间分布模式分析是海浪破碎统计研究的前提。本文提出利用空间点过程统计分析工具研究白冠空间分布模式,并结合实际白冠破碎观测录像资料,计算观测数据的L-函数和K-函数,与Markov chain Monte Carlo(MCMC)方法生成的模拟包迹进行比较,推断得出其白冠空间分布模式类型为空间齐次Poisson过程。研究表明空间点过程统计分析工具适用于白冠破碎研究。     

基于主成分和BP神经网络的智利竹筴鱼渔场预报模型研究

东南太平洋智利竹筴鱼Trachurus murphyi是我国大型拖网渔船队的重要捕捞对象。准确预报中心渔场是提高渔业生产能力的重要工作。本文根据2003—2009年我国船队在东南太平洋海域捕捞智利竹筴鱼的渔捞日志数据,结合海洋遥感获得的海表温度(SST)和海面高度(SSH)等海洋环境因子,利用主成分和BP神经网络方法对智利竹筴鱼中心渔场预报模型进行了研究。研究利用主成分分析法(PCA)得到累计贡献率在90%以上样本的主成分,综合考虑模型测试的精度与速度,基于原始样本和经PCA处理后的主成分分别建立了BP模型,其最优BP模型结构分别为5∶10∶1和3∶7∶1。研究结果表明,经PCA处理后的主成分所建立的BP神经网络模型在训练结果和测试结果上均要优于用原始样本建立的BP神经网络模型,两者的预报准确率分别为67%和60%。     

Optimal Design of Equivalent Water Depth Truncated Mooring System Based on Baton Pattern Simulated Annealing Algorithm简

The highest similarity degree of static characteristics including both horizontal and vertical restoring force-displacement characteristics of total mooring system, as well as the tension-displacement characteristics of the representative single mooring line between the truncated and full depth system are obtained by annealing simulation algorithm for hybrid discrete variables （ASFHDV, in short）. A“baton” optimization approach is proposed by utilizing ASFHDV. After each baton of optimization, if a few dimensional variables reach the upper or lower limit, the boundary of certain dimensional variables shall be expanded. In consideration of the experimental requirements, the length of the upper mooring line should not be smaller than 8 m, and the diameter of the anchor chain on the bottom should be larger than 0.03 m. A 100000 t turret mooring FPSO in the water depth of 304 m, with the truncated water depth being 76 m, is taken as an example of equivalent water depth truncated mooring system optimal design and calculation, and is performed to obtain the conformation parameters of the truncated mooring system. The numerical results indicate that the present truncated mooring system design is successful and effective.     

Numerical Simulation of Dynamic Response of A Net Cage for Flatfish in Waves简

A numerical model of flatfish cage is built based on the lumped mass method and the principle of rigid body kinematics. To validate the numerical model, a series of physical model tests are conducted in the wave flume. The numerical results correspond well with the data sets from physical model test. The effect of weight of bottom frame, height of fish net and net shape on motion responses of fish cage and tension force on mooring lines is then analyzed. The results indicate that the vertical displacements of float collar and bottom frame decrease with the increase in the weight of bottom frame; the maximum tension force on mooring lines increases with the increasing weight of bottom frame. The inclination angles of float collar and bottom frame decrease with the increasing net height; the maximum tension force increases obviously with the increase of net height.     

中国东南部与川渝陕甘地区夏季降水 30～60天CISO的反相现象

利用1979～2010年NCEP/NCAR逐日再分析资料和我国753站逐日降水资料,研究了中国东南部和川渝陕甘地区夏季降水30～60天气候季节内振荡（Climatological IntraSeasonal Oscillation,CISO）的反相现象。结果显示两个区域夏季降水CISO在7月中旬之前存在显著的反相关系,且在传播特征上有明显差异。川渝陕甘地区降水局地低频振荡显著,中国东南部降水CISO北传特征清晰。低频环流分析表明,对流层低层低频槽、脊的更替形成了川渝陕甘地区降水CISO的“驻相”振荡,低频气旋式、反气旋式环流位置的移动则产生了中国东南部降水CISO的北传。CISO垂直环流显示上升支与下沉支正好处于川渝陕甘地区与中国东南部,较好地反映了低频降水在两区域的相反变化。中国东南部、长江中下游与川渝陕甘地区三者之间存在动力学上的关联,这可部分地解释川渝陕甘地区和中国东南部之间降水CISO的反相关系。这种反相关系的形成还与气候态下的西太平洋副热带高压和贝加尔湖附近大陆高压脊的季节内变化有关。揭示中国东南部与川渝陕甘地区之间降水CISO的反相现象对于丰富人们对我国夏季风区低频振荡局地特征的认识和理解降水季节内振荡产生机制有重要意义。     

基于.Net的人地挂钩动态监测监管系统的设计与实现

人地挂钩是统筹城乡发展中土地利用方面所采用的新政策,是一种新的土地管理模式,新的城乡互动发展模式。采用ArcgGIS开发平台,ASP.net,c#等技术建立的河南省人地挂钩动态监测监管系统,能够对全省土地综合整治试点项目、人地挂钩指标交易实现在线监管和实时监控,加大了人地挂钩工作中的透明度,提高了工作效率,为中原经济区"三化"进程提供有力的保障。     

Modeling Users' Behavior for Testing the Performance of a Web Map Tile Service

Web Map Tile Services (WMTS) are widely used in many fields to quickly and efficiently visualize geospatial data for public use. To ensure that a WMTS can successfully fulfill users' expectations and requirements, the performance of a service must be measured to track latencies and bottlenecks that may downgrade the overall quality of service (QoS). Traditional synthetic workloads used to evaluate WMTS applications are usually generated by repeated static URLs, through randomized requests, or by an access log replay. These three methods do not take request characteristics and users' behaviors into consideration, while access logs are not available for systems still under development. Thus, the evaluation outcomes obtained by these methods cannot represent the real performance of online WMTS applications. In this article a new workload model named HELP (Hotspot/think‐timE/Length/Path) is proposed to measure the performance of a prototype WMTS. This model describes how users browse a WMTS map and statistically characterizes complete map navigation behaviors. Then, the HELP model is implemented in HP LoadRunner and used to generate a synthetic workload to evaluate the target WMTS. Experimental results illustrate that the performance representation of the HELP workload is more accurate than that of the other two models, and how a bottleneck in the target system was identified. Additional statistical analysis of request logs and “hotspots” visualizations further validate the proposed HELP workload.