Testing a four-dimensional variational data assimilation method using an improved intermediate coupled model for ENSO analysis and prediction

A four-dimensional variational (4D-Var) data assimilation method is implemented in an improved intermediate coupled model (ICM) of the tropical Pacific. A twin experiment is designed to evaluate the impact of the 4D-Var data assimilation algorithm on ENSO analysis and prediction based on the ICM. The model error is assumed to arise only from the parameter uncertainty. The “observation” of the SST anomaly, which is sampled from a “truth” model simulation that takes default parameter values and has Gaussian noise added, is directly assimilated into the assimilation model with its parameters set erroneously. Results show that 4D-Var effectively reduces the error of ENSO analysis and therefore improves the prediction skill of ENSO events compared with the non-assimilation case. These results provide a promising way for the ICM to achieve better real-time ENSO prediction.     

硅硼镁铝矿复杂（高次）孪晶的微结构研究

本文用透射电子显微技术研究了硅硼镁铝矿的显微结构特征。研究结果表明:该矿物发育复杂(高次)生长孪晶,即(202)孪晶,(280)(202)二次孪晶,(04I)(280)(202)三次孪晶和(443)四次孪晶。并阐明了矿物高次孪晶的相互结构关系。同时,在TEM明场象中观察到了该矿物复杂孪晶对应的结晶形态。笔者还总结了低对称复杂孪晶显微结构的分析方法。     

天然金刚石孪晶的X射线衍射与形貌研究

本文利用X射线衍射和形貌术方法研究了辽南天然金刚石孪晶体。发现晶体中存在有孪晶界、位错、生长带和亚结构等多种缺陷。文中对部分位错进行了详细讨论,并确定其特征量;同时还分析各种缺陷的空间分布特点及其与孪晶界面的关系。     

Sloped multi‐roller isolation devices for seismic protection of equipment and facilities

The rolling motion of mutually orthogonal rollers respectively sandwiched between two bearing plates in which one or both have V‐shaped sloping surfaces makes the sloped rolling‐type isolation device have an excellent in‐plane seismic isolation performance. In this study, the sloped rolling type isolation device in which a single roller moves between two V‐shaped sloping surfaces along each principle horizontal direction is refined by incorporating multi‐roller, built‐in damping, and pounding prevention mechanisms. The associated dynamic behavior is further clarified, and a simplified twin‐flag hysteretic model, which can be easily applied in most commercial computational tools is then proposed. Seismic simulation tests on the refined isolation devices (i.e. the sloped multi‐roller isolation devices) with different design parameters such as sloping angles of bearing plates and built‐in damping capabilities, together with a raised floor system by employing the sloped multi‐roller isolation devices, were conducted. Not only is the efficiency of the sloped multi‐roller isolation devices in seismically protecting the important objects, but also the practicability and accuracy of the proposed simplified numerical model in predicting the seismic responses of the sloped multi‐roller isolation devices is experimentally verified. Copyright © 2014 John Wiley & Sons, Ltd.     

地下水位循环变化时隧道开挖对群桩的长期影响研究

为解决地下水位随季节升降变化时隧道开挖对邻近桩基的长期影响难题,通过三维离心模型试验,研究了地下水位循环变化时隧道对群桩的长期影响。主要分析水位循环变化时地表长期沉降、桩顶长期附加沉降、桩身长期附加弯矩和附加轴力的变化规律。试验结果表明：在隧道附近,地下水位循环变化尤其是降水对地表长期沉降影响更为明显。地表长期附加沉降随着地下水位循环次数增加而增大,且呈衰减式变形,即使经过3次水位升降循环也不能稳定;桩基长期附加沉降显著,其附加沉降量占总沉降量的50%以上;前、后桩的长期附加轴力基本为正值,桩总轴力增加,对既有受压桩极为不利,附加轴力拐点位置及最大值有所区别;经过3次地下水位循环变化后,前、后桩桩身弯矩反弯点个数减少,但桩身最大附加弯矩均明显变大,当达到极限弯矩,桩身出现塑性铰,这对穿越厚软弱层地基中的既有受压柔性桩极为危险。     

SAGD平行井套管内磁引导模拟实验

SAGD平行井是稠油开采的重要方法,它对两井的空间轨迹要求较高。相比较常规随钻仪器,借助于MGT磁定位的磁引导技术有利于进一步提高钻孔轨迹检测精度和检测效率。目前还未见国产同类成熟仪器应用的报道。主要介绍了室外套管地面模拟实验,研究轨迹精度与套管内磁响应之间的关系,为仪器的实际应用提供修正数据和技术支撑。实验以通电螺线管作为磁发射源,并置于φ139.7 mm套管中,以磁传感器为接收源,采集数据,最后由电脑解析数据算出两者的相对位置。实验时不断改变传感器与套管的相对位置,以模拟钻头钻进的真实情况。实验共采集了18种形态,共198点位数据。在修正前,计算的总距离平均误差在7%左右,平面误差为9.4%左右。修正后误差为之前的一半。结果表明,计算点能够真实反映轨迹的实际方向。     

苏州与上海孪生城市模式的形成机理及其区域效应

在对美国进行大量实证分析的基础上,艾伦从理论上推导出的孪生城市模式丰富和发展了区域空间结构理论。1990年代以后,苏州在跨国公司投资作用下的快速崛起,已与上海初步构成了一种功能上互补的共生关系,即孪生城市模式。这一模式的形成主要导源于以下两方面的原因。从行政原因上看,苏州与上海由于分属两个省级行政单元,经营成本、产业政策自1980年代以来一直有着较为明显的差异;从经济原因上看,苏州与上海仅距不到90 km、位居上海都市圈的内圈层,且离虹桥机场约50 km。苏州的快速崛起以至于苏沪孪生城市的形成,产生了多方面的区域效应。苏州与无锡本是一对水平相当、产业性质类似的城市,现已出现了明显的差异化发展态势,从而为在此基础上城市合理分工的形成奠定了基础;苏州位居省级行政单元的交界,因此苏州与作为省会城市的南京构成了广义上的双核结构模式;上述因素的综合作用,使得我们可以构建起沪宁沿线城市合理分工的多重空间组合模式。     

水泥土(砼)抗压试件尺寸表面约束对强度的影响

推导了圆柱体试件和长（立）方体试件,分别在不同表面摩擦力和不同高宽（径）比下基于双剪屈服准则下抗压强度的理论计算公式,并与实验结果比较所得结果与实验结果甚为吻合。其理论计算与实验结果都说明,试件尺寸的不同与表面抹油与否对水泥土抗压强度均有一定的影响。其高宽（径）越大,其强度越低且越趋于一定值。试件上下表面不摸油其抗压强度略高抹油情况。