Timing of UHP metamorphism in the Hong’an area,western Dabie Mountains,China: evidence from zircon U–Pb age,trace element and Hf isotope composition

The Hong’an area (western Dabie Mountains) is the westernmost terrane in the Qinling-Dabie-Sulu orogen that preserves UHP eclogites. The ages of the UHP metamorphism have not been well constrained, and thus hinder our understanding of the tectonic evolution of this area. LA-ICPMS U–Pb age, trace element and Hf isotope compositions of zircons of a granitic gneiss and an eclogite from the Xinxian UHP unit in the Hong’an area were analyzed to constrain the age of the UHP metamorphism. Most zircons are unzoned or show sector zoning. They have low trace element concentrations, without significant negative Eu anomalies. These metamorphic zircons can be further subdivided into two groups according to their U–Pb ages, and trace element and Lu–Hf isotope compositions. One group with an average age of 239 ± 2 Ma show relatively high and variable HREE contents (527 ≥ Lu_N ≥ 14) and ¹⁷⁶Lu/¹⁷⁷Hf ratios (0.00008–0.000931), indicating their growth prior to a great deal of garnet growth in the late stage of continental subduction. The other group yields an average age of 227 ± 2 Ma, and shows consistent low HREE contents and ¹⁷⁶Lu/¹⁷⁷Hf ratios, suggesting their growth with concurrent garnet crystallization and/or recrystallization. These two groups of age are taken as recording the time of prograde HP to UHP and retrograde UHP–HP stages, respectively. A few cores have high Th/U ratios, high trace element contents, and a clear negative Eu anomaly. These features support a magmatic origin of these zircon cores. The upper intercept ages of 771 ± 86 and 752 ± 70 Ma for the granitic gneiss and eclogite, respectively, indicate that their protoliths probably formed as a bimodal suite in rifting zones in the northern margin of the Yangtze Block. Young Hf model ages (T _DM1) of magmatic cores indicate juvenile (mantle-derived) materials were involved in their protolith formation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Static Analysis of Collision Strength of Offshore Platform

In this paper a numerical analysis method combining FEM incemental technique with limit analysis concept is proposed for the study of the static strength of offshore platform in collision. Large deformation and plasticity are accounted for and the limit yield surface expressed by generalized stress for a tubular section is derived. The modified stiffness matrix of space beam element is formulated by Plastic Node Method. The buckling behavior of beam columns can also be taken into account. It can trace the generation of plastic hinges during loading and finally the ultimate strength of offshore platform against collision is obtained.     

Elasto-Plastic Analysis of Tubular Joints of Offshore Platforms by Finite Element Method

The plastic node method is reformulated by the variational principle and is applied to elasto-plastic finite element analysis of tubular joints, eventually including the effect of internal and external gussets, stiffener rings, etc., if necessary. Four different joints are studied here in detail for the elasto-plastic behavior, the strain at the hot spot, the strain concentration factor around the intersection line, and the propagation of the plastic region with loading up to collapse in order to determine the ultimate strength, safety factor, and development of the plastic field. The present results are in good agreement with the experimental results.     

Underice Operation of SJT-5 ROV

- The authors have used a low-cost ROV of observation type for underice surveying of the Nen-Jiang Cross-river oil pipe line in the Da Qing oil field. The operation method, process and the safety measures for severe cold areas are presented. The fruitful tries and experience may be useful to ROV operators in severe cold areas.     

CHIMEHERB人工皮使用的体会

从1989年4月～1990年10月,我科在69例病人中使用CHIMEHERB人工皮,覆盖治疗了供皮区,Ⅱ°烧伤创面、脱痂创面的残余肉芽创面.临床应用表明:CHIMEHERB人工皮能加快创面的愈合,是目前较好的一种创面覆盖物,用人工皮覆盖创面2～3天后,人工皮干燥,不需再换药,可减轻病人的痛苦.     

Design of Mooring System for Oil Storage Vessels

The floating oil storage system has been proposed as a new facility for Strategic Petroleum Reserve (SPR) in China. Mooring is one of the key technologies to ensure the safety, reliability, and performance of the oil storage system. This paper describes the concept, analysis, design and reliability of the mooring system. For mooring system design of these oil vessels, analysis is essential of the behavior of the vessel in connection with mooring facilities of nonlinear resilience. A nonlinear mathematical model for analyzing a moored vessel is established and solved. Some results of numerical simulations are presented. Assessment of the safety regarding the mooring system in terms of failure probability is carried out. Another simulation model for calculating the failure probability of the mooring system is proposed. The design parameters that have an influence on the characteristics of the failure probability have been identified. The simulation results show that the mooring system has an annual reliab     

GPS RTK技术及其在管线勘控中的应用

针对GPS RTK技术应用中的工作条件、数据链传输、误差特性及质量控制等问题,结合管线勘控测量的作业特点,提出了提高RTK作业精度若干方法.     

Study on the characteristics of rock failure strain and acoustic emission field for two parallelling faults with the same slip direction including asperities

Introduction Concerning about research on grouped-earthquake seismogenic and occurrence, at present it is only limited on the stage of the theoretical analysis and numerical model. For instance, ZHANG (1987) simulated the grouped-earthquake generation and physical mechanism making use of spring-block principle. Applying for non-linear dynamic model, referring to Chinese continental plate as object, LI, et al (1997) performed the numerical simulation on the seismogenic and occurring of group…     

河南经济技术开发区发展前景与对策

文章阐述了经济技术开发区在区域经济发展过程中的作用。根据河南省经济技术开发区的发展现状和存在的问题，分析了加入WTO后开发区所面临的机遇和挑战，并在此基础上从开发区环境营造，运行机制，筹资方式，产业发展，城市建设等方面提出了加快河南省经济技术开发区发展的对策。     

鞍山市西郊区水位预测

根据鞍山市西郊区水文地质条件，建立了双层渗流二维平面系统的数学模型：应用Galerkin有限元法求解模型，从模型的计算结果可见该区观测点水位绝对误差较小，达到了规范要求的计算精度，同时，在此区内有一个大漏斗，在东南的铁西一带也有一个小漏斗。由于铁西一带是主要开采水源区，开采水量较大，所以漏斗逐渐向外扩大且水位有明显下降的趋势。这一变化规律与实际水位一致，说明计算水位基本上反映了实际水位空间变化的规律。因此根据模拟参数利用此模型对该地区进行了水位预测，共预测了四年的水位状况，并依据水位的预测结果对该区的水资源开发利用提出了合理建议。