环境工程地质浅论

论述了工程地质与环境工程地质的相互关系，环境工程地质的内容及当前研究的任务。     

大地测量学的进展和我们的任务

在回顾现代大地测量和我国大地测量工作历史的基础上,对90年代我国大地测量任务,其中包括国家二期一等水准复测;国家GPS网布设;重力场参数精化;GPS卫星追踪站建立;沿海地区陆海相对垂直位移研究和青藏地区壳形变监测等理论和实践工作,作了论述。     

GPS-RTK作业的若干技术问题与思考

文章阐述了全球定位系统RTK作业的几种常用方式，对影响其实时流动作业的若干技术问题诸如转换参数的选择、参数的区域性、时间性、完整性和参数的检验等问题进行了讨论，并对影响RTK作业精度的主要误差源进行了分析。     

将高精度地理信息获取作为基础测绘重要战略任务的思考

高精度地理信息具有提供更高空间定位精度和更强空间关系表达能力的优势。“十四五”期间,高精度地理信息获取作为基础测绘重要战略任务,其相关成果将为经济社会发展和自然资源综合管理提供更好的空间参考依据。本文从高精度地理信息的获取进展出发,分析了高精度地理信息产品的需求形势和对基础测绘服务能力的提升作用,以及高精度地理信息获取和产品提供过程中遇到的问题,提出了提升高精度地理信息获取和产品提供能力的相关建议。     

1961—2016年祁连山区季节性干旱综合指数特征分析

采用Z指数和熵权理论,构建了干旱综合指数作为干旱强度评价标准,对祁连山区季节性干旱特征及其空间分布规律进行了深入剖析。结果表明:1961—2016年季节性干旱强度普遍减弱,其中春秋两季显著减弱,夏季明显减弱;尽管20世纪60—70年代、90年代为季节性干旱频发与重发时段,但从2000年以来夏旱与冬旱却比较频繁,不容忽视。干旱强度由强到弱依次为冬季、夏季、春季和秋季,冬季干旱程度最强;在干旱波动性上秋季最强,冬季次之,春季最弱。春夏秋三季南侧比北侧干旱,冬季北侧比南侧干旱,其中冬季干旱范围最为广泛,尤以酒泉为中心的北侧区域最为显著。在研究时段内祁连山南北两侧干旱强度逐渐减弱,南侧明显减弱,枯草期干旱强度减弱程度尤为显著。本研究为祁连山区干旱评价提供了参考依据。     

Toward Equal Opportunity of Primary Education: Introducing a Lottery into China’s Proximity-Based Enrollment System

A serious spatial inequality of educational opportunity in school enrollment persists worldwide. The use of random mechanisms in school allocation might improve spatial equality, with lotteries applied in some choice-based systems. China uses a proximity-based assignment, yet the optimization of spatial equality of educational opportunity by introducing a lottery has received little consideration. To achieve the maximum spatial equality of educational opportunity, in this study, a random proximity-based model was developed, and the swarm optimization method was used to solve the model. A case study in the Shijingshan district of Beijing was used to illustrate the model outputs. For comparison, a proximity-based model was also developed and solved. After introducing a lottery into a proximity-based enrollment system, the spatial disparity of educational opportunity was reduced by 70 percent. The average travel distance to school increased 3.5-fold but was still much less than the actual average distance of 4.3?km. Relaxing the maximum travel distance constraint could significantly improve spatial inequality. Although total equality was significantly improved, only 51 percent of students benefited from increased opportunities, which implies that the model could be adopted in a centralized institutional context, such as China, but might be ineffective in a democratic system.     

Inferring user tasks in pedestrian navigation from eye movement data in real-world environments

Eye movement data convey a wealth of information that can be used to probe human behaviour and cognitive processes. To date, eye tracking studies have mainly focused on laboratory-based evaluations of cartographic interfaces; in contrast, little attention has been paid to eye movement data mining for real-world applications. In this study, we propose using machine-learning methods to infer user tasks from eye movement data in real-world pedestrian navigation scenarios. We conducted a real-world pedestrian navigation experiment in which we recorded eye movement data from 38 participants. We trained and cross-validated a random forest classifier for classifying five common navigation tasks using five types of eye movement features. The results show that the classifier can achieve an overall accuracy of 67%. We found that statistical eye movement features and saccade encoding features are more useful than the other investigated types of features for distinguishing user tasks. We also identified that the choice of classifier, the time window size and the eye movement features considered are all important factors that influence task inference performance. Results of the research open doors to some potential real-world innovative applications, such as navigation systems that can provide task-related information depending on the task a user is performing.     

遥感影像处理特征及数据密集型任务调度算法研究

针对云计算技术在遥感影像处理中的应用问题,对于其任务特征以及调度问题进行了研究。首先定义了遥感影像处理工作流,并在特征分析的基础上对任务类型进行了划分,将任务划分为数据密集型和计算密集型两种。针对数据密集型任务调度问题,通过建立流程间的数据依赖度矩阵和数据集划分制定调度策略,设计了以减少数据传输次数为目标的调度算法。实验结果表明,该算法与随机算法相比,可以有效减少数据集、数据服务器数量和不同比例的固定数据集等多种情况下的数据传输次数,该算法能够满足常用数据密集型任务的调度需求,如计算航段信息、计算缩略图同名像点等。     

Implementation of the parallel mean shift-based image segmentation algorithm on a GPU cluster

The mean shift image segmentation algorithm is very computation-intensive. To address the need to deal with a large number of remote sensing (RS) image segmentations in real-world applications, this study has investigated the parallelization of the mean shift algorithm on a single graphics processing unit (GPU) and a task-scheduling method with message passing interface (MPI)+OpenCL programming model on a GPU cluster platform. This paper presents the test results of the parallel mean shift image segmentation algorithm on Shelob, a GPU cluster platform at Louisiana State University, with different datasets and parameters. The experimental results show that the proposed parallel algorithm can achieve good speedups with different configurations and RS data and can provide an effective solution for RS image processing on a GPU cluster.     

海域无人机监视监测业务流程设计

文章主要探讨海域无人机监视监测业务流程,针对目前海域动态监视监测工作中无人机管理模式及作业流程的现状,结合海域资源开发管理业务需求,阐述规范无人机作业流程的必要性。按照无人机监测任务的紧迫程度分为常规监测任务和应急监测任务,以规范无人机业务流程、提高无人机作业效率、保障无人机作业安全为目的,并结合无人机业务工作中的实际情况对两类监测任务的无人机作业流程进行了探讨与设计。