各向异性介质填充波导散射特性的三维54参量边缘元分析

本文将54参量边缘元和"边界行进"及Galerkin法相结合,分析了各向异性介质填充波导的散射特性.该方法有效地提高了计算精度和效率,明显地降低了对内存的需求,并消除了伪解.文中给出的计算实例,很好地证实了本文方法的这些优点.     

三维PML吸收边界条件在微带线不连续性问题分析中的应用

将完全匹配层（PML）吸收边界条件从求解二维TE／TM模问题推广到求解三维混合模传输线问题,通过对各种三维微带线不连续性结构散射特性的计算表明,文中给出的电磁PML吸收边界条件保持了二维情况下宽带、高精度的优点,在复杂结构的FDTD分析中具有重要的实用意义。     

矿产勘查综合经济指标选择

矿产勘察的基本任务是根据国民经济和社会发展的需要及地质条件的可能,寻找和查明具有经济价值的工业矿床,为国民经济建设提供矿产资源依据,为矿山企业建设提供矿物原料基地和矿产储量。矿产勘察评价工作不仅是一个运用地质科学和有关自然科学的理论与方法,不断探索和认识矿床的过程,还是一项地质和技术经济的综合性实践活动。     

Investigations of deep resistivity structures at the Wairakei geothermal field

The Wairakei geothermal field was the proving ground for the use of electrical resistivity methods for geothermal exploration. At this site it was first demonstrated that a large contrast in resistivity existed between geothermal ground and the cold surroundings. Within the top 500 m of the geothermal field, low-resistivity (5–10 Ωm) reflects the effects of both the hot saline water in the pore spaces and the conductive rock-matrix. The first surveys at Wairakei used a Wenner array (a ∼550 m) to measure the resistivity values along tracks throughout the field; contour maps of the resistivities were used to estimate the lateral extent of the geothermal waters at a few hundred metres depth. In the late 1960s the Wenner array was superseded by the Schlumberger array (AB/2 = 500 m and 1000 m), which enabled deeper penetration and better definition of the extent of the geothermal waters. These early surveys showed that the bounds of the geothermal waters were often sharp, leading to the concept that a ‘resistivity boundary’ could be defined for New Zealand's liquid-dominated geothermal fields. As new methods of measuring electrical structure with greater precision became available, Wairakei was often chosen as the testing ground.     

塔尔沟地区1/5万矿产远景调查地质特征及找矿方向

祁连山西段塔尔沟地区,大地构造位置位于祁连山中间隆起带和北祁连地向斜带的结合部位。区域内构造发育,地层出露较齐全,前长城系是钨、钼、铜、铅、锌的主要赋矿层位;长城系朱龙关群浅变质低绿片岩相,是钨、钼、铜、铁的主要赋矿层位;蓟县系镜铁山群变质绿片岩相,是铁、铜矿床的主要赋矿层位。奥陶系阴沟群,为典型蛇绿岩建造,是北祁连火山岩型铜矿床的主要赋矿地层。因此,根据区域成矿条件和矿产分布规律分析,该区域为有色金属、黑色金属、贵金属矿产的产出地,矿产调查具有较好的前景。     

Performance of Active and Passive Methods for Measuring Low-Frequency Surface Wave Dispersion Curves

This paper examines the consistency between surface wave dispersion curves measured at wavelengths of up to 600 m using active and passive methods at sites in the Mississippi Embayment. Large-diameter (200 m) circular receiver arrays were deployed at five deep soil sites located in Tennessee, Arkansas, and Missouri to record ambient ground vibrations at low frequencies. Measurements were performed at the same locations using linear receiver arrays and actively generated low-frequency energy using the recently developed Network for Earthquake Engineering Simulation (NEES) field vibrator (termed Liquidator). Characteristics of the ambient wavefield measured at the five sites in the Mississippi Embayment are presented along with comparisons between the surface wave dispersion curves obtained from the active and passive measurements at each site. The ambient wavefield measurements exhibited peak levels in the frequency range of 1–5 Hz. Surface wave dispersion curves developed from frequency-wavenumber (f-k) processing of the active and passive methods were in good agreement at four of the sites, with phase velocities from the passive measurements within 5–10 % of the active-source measurements out to wavelengths of about 550 m. Improved comparisons were obtained at the fifth site by applying high-resolution f-k processing.     

包含定位长大裂隙的节理岵体连通率的计算及应用

岩体中节理面的分布情况极为复杂,除了那些大量呈随机分布的结构面外,尚有一些数量相对较少,但规模较大,利用近代勘探手段可以准确定位的长大裂隙。这些长大裂隙,对岩体的强度和稳定性起着举足轻重的作用。针对工程的实际情况,在应用网络模拟进行连通率分析计算时,将这些长大裂隙与随机结构面网络耦合在一上结,使连通率计算成果更加合理。     

含不连续面巷道的动力破坏过程数值分析

利用新近开发的动态版岩石破裂过程分析系统RFPA2D模拟了动力扰动下含不连续面巷道的破坏过程,从细观角度分析了不同宽度不连续面的岩石巷道在动力扰动下破坏的规律,并和未含不连续面巷道结构的相应情况进行比较,探讨了含不连续面巷道结构在动载荷作用下的力学特性,结果表明不连续面对应力波衰减作用明显,对巷道的稳定与破坏影响较大.     

双向载荷作用下无限大板中源于正方形孔的分支裂纹的应力强度因子

为研究源于正方形孔的一对分支裂纹问题提出一种边界元法,该边界元方法由Crouch与Starfield提出的常位移不连续单元和裂尖位移不连续单元构成.在该边界元方法的实施过程中,左、右裂尖位移不连续单元分别置于裂纹的左、右裂尖处,而常位移不连续单元则分布于除了裂尖位移不连续单元占据的位置之外的整个裂纹面及其他边界.算例说明,这种边界元法对计算平面弹性复杂裂纹的应力强度因子非常有效.给出的双向载荷作用下无限大板中源于正方形孔的一对分支裂纹的应力强度因子的详细数值结果,可以揭示双向载荷参数对应力强度因子的影响.     

Challenges and R&D opportunities of smart distribution grids in China

In this paper, 5 investigations on the current states of power distribution grids in China have been introduced that cover the surveys of the practical distribution asset utilization, the simultaneity factor of feeder loading, the load compositions and characteristics, the urban reliability and the integration of distributed generations of renewable resources. Based on the survey results in the investigations, 12 Facts are clearly presented. It shows that the challenges to modernize the distribution grids in China are to improve the asset utilization rates, the electricity efficiencies and the reliability of distribution systems, as well as to integrate increasing amount of variable distributed renewable resources. Furthermore based on the challenges, 8 R&D opportunities have been identified.