An application of the A-4DEnVar to coupled parameter optimization

In variational methods, coupled parameter optimization (CPO) often needs a long minimization time window (MTW) to fully incorporate observational information, but the optimal MTW somehow depends on the model nonlinearity. The analytical four-dimensional ensemble-variational (A-4DEnVar) considers model nonlinearity well and avoids adjoint model. It can theoretically be applied to CPO. To verify the feasibility and the ability of the A-4DEnVar in CPO, “twin” experiments based on A-4DEnVar CPO are conducted for the first time with the comparison of four-dimensional variational (4D-Var). Two algorithms use the same background error covariance matrix and optimization algorithm to control variates. The experiments are based on a simple coupled ocean-atmosphere model, in which the atmospheric part is the highly nonlinear Lorenz-63 model, and the oceanic part is a slab ocean model. The results show that both A-4DEnVar and 4D-Var can effectively reduce the error of state variables through CPO. Besides, two methods produce almost the same results in most cases when the MTW is less than 560 time steps. The results are similar when the MTW is larger than 560 time steps and less than 880 time steps. The largest MTW of 4D-Var and A-4DEnVar are 1 200 time steps. Moreover, A-4DEnVar is not sensitive to ensemble size when the MTW is less than 720 time steps. A-4DEnVar obtains satisfactory results in the case of highly nonlinear model and long MTW, suggesting that it has the potential to be widely applied to realistic CPO.     

Numerical study of pillar stresses and interaction effects for twin rock caverns

Large underground caverns are increasingly being considered for the construction of industrial facilities and transportation infrastructure in order to optimize the use of surface land in large urban cities. Due to the geological constraints underground, it is sometimes necessary to construct a cavern close to an existing cavern. Pillars serve as an underground support element in twin caverns, without which it is difficult to sustain the weight of the overburden materials. If the strength of a pillar is exceeded, it will fail, and the load that it carried will be transferred and thereby contribute to the collapse of the twin caverns. The lack of confinement in slender pillars also contributes to the complete collapse of pillars at relatively low stress magnitudes. From a design point of view, understanding the pillar failure mechanism and the interaction effect between twin caverns is essential. This paper presents a numerical investigation on the influence of various design parameters on twin cavern interaction. Pillar performances with respect to the changes to the maximum principal stress in the pillar, the peak vertical stress, and the peak principal stress difference in the pillar core are studied in order to examine the failure mechanisms and to identify situations in which there is significant cavern interaction and overlap of the plastic zones. Copyright © 2014 John Wiley & Sons, Ltd.     

基于虚幻引擎的智能矿山数字孪生系统云渲染技术

HTML5、WebGL、云渲染等技术为浏览器、移动端、XR等多种终端的可视化渲染提供了重要技术支撑。本文分析比较了其优缺点,并采用虚幻引擎4的云渲染技术,采用某煤矿的倾斜摄影、BIM、巷道、设备、三维地质模型开展了系统设计与测试,分析了云渲染的效率和效果,实现了数字孪生云渲染技术在智能矿山的应用。     

激光扫描与无人机空地一体融合测量应用

测量是工程项目建设的重要基础,贯穿从规划设计、施工到竣工整个工程建设的全生命周期。近年来,越来越多的工程开始考虑全流程利用数字孪生进行项目管理应用。传统的测量方法存在外业周期长和成果抽象难等缺点,难以进行可视化表达。本文利用Trimble SX10三维影像激光扫描仪结合无人机进行空地一体融合测量,并总结了相应的技术方法和流程。与传统测量手段相比,本文方法不仅缩短了测绘周期,解决了夜间光学测绘的难题,成果还可数字可视化表达。     

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。     

Modulation of Twin Tropical Cyclogenesis by the MJO Westerly Wind Burst during the Onset Period of 1997／98 ENSO

The modulation of twin tropical cyclogenesis in the Indian-western Pacific Oceans by the Madden-Julian Oscillation (MJO) during the onset period of 1997/98 ENSO is explored for the period of September 1996 to June 1997 based on daily OLR, NCEP/NCAR wind vector, and JTWC best track datasets. The MJO westerly wind burst associated with its eastward propagation can result in a series of tropical cyclogeneses in a multi-day interval. Only in the transition seasons are pairs of tropical cyclones observed in both the tropical sectors of the Indian-western Pacific Oceans. Two remarkable twin tropical cyclogeneses probably modulated by the MJO westerly wind burst are found: one is observed in the Indian Ocean in the middle of October 1996, and the other is observed in the Western Pacific Ocean in late May 1997. The twin tropical cyclogenesis in mid-October 1996 is observed when the super cloud cluster separates into two isolated clusters by the enhanced westerly wind, which is accompanied by two independent vortices in the equatorial tropical sectors. The other one, in late-May 1997, however, is characterized by one cyclonic flow that later results in another cyclonic cell in its opposite equatorial sector. Thus, there are two very important conditions for twin cyclogenesis: one is the MJO westerly wind straddling the equator, and the other is the integral super cloud cluster, which later splits into two cloud convective clusters with independent vortices.     

A series solution for surface motion amplification due to underground twin tunnels: incident SV waves

A series solution of displacement response of the ground surface in the presence of underground twin tunnels subjectcd to excitation of incident plane SV waves is derived by using Fourier-Bessel series expansion method. The numerical parametric study shows that underground twin tunnels significantly amplify the nearby surface ground motion. It is suggested that the effect of subways on ground motion should be considered when the subways are planned and designed.     

天然水晶片中双晶纹的成因及其鉴定意义

从结晶学入手，分析了双晶纹的成因，探讨了合成水晶中双晶纹形成的可能性，提出了双晶纹可以作为天然水晶片的鉴定依据之一。     

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。     

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。