Seismic reflection study of recessional moraines beneath Lake Superior and their relationship to regional deglaciation

Approximately 8000 km of continuous seismic reflection profiles throughout Lake Superior were examined for evidence of recessional moraines and other ice-margin deposits associated with the retreat of late Wisconsin ice. These features are correlated with the record of glacial-lake evolution in western Lake Superior. An offlapping sequence of glacial and glacial-lacustrine dediments overlying bedrock is recognized in west-central Lake Superior that is progressively younger to the northeast. The sequence underlies more recent glaical-lacustrine and postglacial sediments. Four facies are recognized on the basis of geomorphologic and acoustic properties and are interpreted to represent a southwest-to-northeast assemblage of: proglacial stratified drift (facies A), drift in major end moraines (facies B), till deposited as glacial retreat resumed, or possibly late-stage ablation till (facies C), and basal till (facies D). The prominent moraines of facies B are unusually thick and are believed to mark the ice-margin shorelines of successive major proglacial lakes that formerly occupied parts of western Lake Superior. The moraines are tentatively correlated with Glacial Lake Duluth (unit 1), Glacial Lake Washburn (unit 2), and Glacial Lake Beaver Bay (unit 3), the most prominent of lakes drained via the progressively lower outlets via the Moose Lake/ Brule-St. Croix Rivers, the Huron Mountains, and the Au Train-Whitefish regions, respectively.     

Point defects and non-stoichiometry in forsterite

Existing experimental evidence suggests that in pure Mg-forsterite with a fixed Mg/Si ratio, vacancies and interstitials on the Mg sublattice are the dominant intrinsic point defects, while O vacancies and conduction-band electrons are the primary oxygen-deficient defects. Orthopyroxene appears to dissolve readily in pure Mg-forsterite at high temperatures, the change in Mg/Si ratio being accommodated by Mg vacancies and Si interstitials; as a consequence, upper-mantle forsterite may be substantially non-stoichiometric. It is postulated that the amount of Fe that can be oxidized in the forsterite phase is directly related to the excess Si present, either incorporated in the structure, or available from another phase richer in SiO₂ such as pyroxene.     

Evidences for a low-velocity core-mantle transition zone

Using the spectral ratios $\text{P}\text{PcP}\text{,}\text{ScS}{}_{\mathrm{n+1}}\text{ScS}{}_{\mathrm{n}}\text{,}\text{sScS}{}_{\mathrm{n+1}}\text{sScS}{}_{\mathrm{n}}\text{and}\text{SKS}\text{ScS}$, models for the core-mantle boundary are found. The models have close similarity with each other, implying an irregular surface with lateral variation in the core-mantle properties. The models are characterized by two to four low-velocity, high-density layers imbedded between the mantle and the core half space. The velocities of the imbedded layers decrease towards the core boundary with a lower bound of 9.3 km/sec for the compressional wave and 3.5 km/sec for the shear wave. The models fitted to the empirical data support the hypothesis of a finite rigid outer core with a higher bound for the shear velocity of 1.4 km/sec. Based on this finite rigidity in the outer core and a layered core-mantle transition zone, the value of Q for the whole mantle is 2,000. For the outer core Q ranges from 100–1,000 , which may indicate that it is chemically zoned.     

海滩剖面监测技术的应用研究

结合传统水准测量的手段,介绍了一种海滩剖面监测的可行方案,并给出了数据处理方法,为威海核电厂工程的选址提供了参考.     

基于置信度的地址匹配方法初探

针对市域地址数据特点,文章在地址编码和地址匹配现有研究成果的基础上,参照济南市地址使用习惯,提出了一种基于置信度的地址匹配方法。该方法以地址数据库为基础,依托规范化地址编码,利用分词算法和置信度筛选的方法匹配数据,通过人机交互的方式扩充地址库,实现了地址的自动匹配定位,提高了匹配的正确性。     

城市地理编码数据库的研究与实践

地理编码数据库是地理编码技术的重要组成部分,它直接影响到地址匹配的效果。本文在青岛市地址体系的分析研究的基础上,详细阐述了青岛市地理编码数据库的建设流程,包括地址数据获取、地址数据标准化、地址数据入库和地址数据库组织的建设,并对地址数据的更新提出了建议。     

多层级地址语义模型构建及其在疫情防控中的应用

目前城市各部门汇集了大量的地址数据,地址数据呈现多头管理和建设的局面,且没有从地理实体的源头处出发,导致成果无法集约共建及统一共享。本文基于以应用为导向的精细化管理需求,建立多层级地址语义模型和地址资源库,将地址资源库与地理实体挂接,形成地址到栋或单元级的房屋实体唯一地理基座,进而全面支撑智慧城市的建设、运营及管理,并在新冠肺炎疫情防控中进行了积极应用。     

一种基于低功耗蓝牙的室内定位技术

本文提出了一种基于蓝牙基站的室内定位解决方案。该技术方案中,蓝牙基站由低功耗蓝牙模块组成,在需要定位的室内空间均匀部署一定数量的蓝牙基站,每个蓝牙基站可以创建一个信号区域,并周期性地向外界广播自己独有的与位置信息对应的mac(media access control)地址和RSSI(Received Signal Strength Indication)值。当携带有蓝牙终端设备的用户进入该信号区域,就会接收蓝牙基站广播的RSSI值和mac地址,然后通过基于泰勒级数线性化的最小二乘迭代算法进行精确定位。实验结果表明,该系统定位精度在2.5 m以内,满足绝大多数的室内定位需求。     

智慧广州时空云平台地名地址引擎功能及应用

在广州市标准地名地址数据库设计与建立的基础上,面向智慧城市时空云平台管理人员、各政府部门等用户,分别开发了基于C/S架构的离线、基于B/S架构的在线地名地址匹配功能,并以广州市“四标四实”工作为例,详细阐述了标准地名地址数据库及其匹配引擎在智慧城市中的具体应用。     

基于查找表的激光雷达图像快速绘制算法

传统雷达图像的绘制一般采用直接的实时坐标变换算法,这种算法效率较低,而且无法从根本上解决雷达图像的死地址和显示盲区现象根据激光雷达特点以及图像绘制需求,设计并实现了一种基于查找表的激光雷达图像快速算法,能大大提高激光雷达图像的绘制速度,并能够较好地解决图像的死地址和显示盲区现象.