利用虚拟现实技术再现海洋自然地理环境

虚拟现实技术是当代计算机科学的一个研究热点,将虚拟现实技术引入到测绘领域中,为测绘保障提供了一个全新的手段。本文首先分析虚拟现实发展现状,然后着重介绍了虚拟现实技术的系统组成,以及相配套的硬,软件。最后,讨论海洋自然地理环境虚拟现实系统的设计等。     

地学可视化探讨

提出了关于地学可视化的研究框架。地学可视化包括地图可视化、地理信息系统（ Ｇ Ｉ Ｓ） 可视化及其在专业应用领域的可视化。地图可视化与 Ｇ Ｉ Ｓ可视化是地学可视化理论和技术的２ 个基础部分。地学多维图解是从非可视化角度提出的,关于图的地学知识表达、获取及其图的地学问题解的求证原理和方法,是地学可视化的高一级发展阶段。地图可视化中的信息表达交流模型和地理视觉认知决策模型的研究,将从理论上促进地学多维图解模型的进一步发展。基于虚拟现实技术和计算机网络技术的虚拟地理环境是地学可视化、地学多维图解理论和技术发展的最后集成系统。     

中国区域虚拟水战略优势度评价

提出虚拟水战略优势度的概念并对其概念内涵及影响因素进行分析,从4个方面构建包含12个具体指标的综合定量评价指标体系;运用数学方法对中国31个省级行政区虚拟水战略优势度进行定量评价.发现中国虚拟水战略优势度存在显著的地域差异,区域优势度等级存在"两头多,中间少"的结构特点和"东部高、西部低","南部和北部高、中间低"带状空间分布规律.其中北方4省市和东南8省区优势度最大,是全球虚拟水战略背景对其影响最深远的区域,也是中国虚拟水研究及虚拟水战略实践的关键区域.     

基于虚拟现实和物联网的水闸自动化监控系统

利用虚拟现实和物联网技术,根据水闸调度数学模型和制定的闸门运行调度模式来控制闸门的运行,在虚拟现实环境中展示闸门的实时运行状态,并通过传感器实时获取闸门运行、水位、流量等数据,和闸门调度方案的一致性进行检测,对异常信息及时捕获和定位,实现自动化监控的目的。以南京市三汊河河口闸的闸控管理系统建设为例,基于虚拟现实和物联网技术建立的水利闸门自动化监控系统,可以提高水闸调度运行响应速度和能力,实现在线优化调度,提高系统的可靠性和稳定性,保证控制命令的正确执行。     

高频面波方法的若干新进展

面波多道分析方法(MASW)通过分析高频瑞雷波确定浅地表剪切波速度.在过去的20年中,由于该方法具有非侵入性、无损、高效及价格低的特点,越来越受到浅地表地球物理和地质工程学界的重视,视为未来最有希望的技术之一.这篇综述论文将介绍中国地质大学(武汉)浅地表地球物理团队近年来在研究高频面波的传播理论和应用中取得的部分成果.非几何波是一种仅存在于浅地表介质,尤其是未固结的沉积物中的独特的地震波.它的存在对快速而准确地获得表层S波速度有一定价值.我们的研究表明非几何波是一种具有频散特性的泄漏波.泄漏波的存在可能导致将其误认为瑞雷波的基阶或高阶能量,从而造成模式误判.这种模式误判会导致错误的反演结果.我们通过求取高基阶分离后的瑞雷波格林函数证明虚震源法瑞雷波勘探的可行性.这个结果将极大地降低野外瑞雷波勘探成本.勒夫波多道分析方法(MALW)中未知参数比瑞雷波的少,这使得勒夫波的频散曲线比瑞雷波的简单.因此,勒夫波反演更稳定,非唯一性更低.勒夫波数据生成的能量图像通常比瑞雷波的清晰,并具有更高的分辨率,从而可以更容易地拾取精确的勒夫波的相速度.利用雅克比矩阵分析波长与探测深度的关系表明对相同波长的基阶模式而言,瑞雷波的探测深度是勒夫波的1.3~1.4倍;而两种波的相同波长的高阶模式波的探测深度相同.我们也尝试了时间域勒夫波反演.按照勒夫波分辨率将地球模型剖分成了不同尺寸的块体,利用反卷积消除了地震子波对勒夫波波形的影响,通过更新每个块体的S波速度来拟合勒夫波波形,从而获得地下S波速度模型.该方法不基于水平层状模型假设,适用于任意二维介质模型.     

An input–output table based analysis on the virtual water by sectors with the five northwest provinces in China

Virtual water refers to the volumes of water required to produce a commodity or service. It reflects human’s actual consumption of water resources and therefore has certain significance in water resources management. Over the years, the concept of virtual water has caught the attentions of water manager and decision maker. In order to utilize this concept, the accounting and estimation of virtual water is the foundation that lies in this issue. Till now, the accounting methods mainly include the method provided by Food and Agriculture Organization of the United Nations (FAO), water footprint and input–output analysis method. In this paper, we chose Northwest China, which is a typical arid region that is facing with rapid economic development, as the study area and built an Input–Output (IO) analysis method to estimate virtual water among different industry sectors in the northwest China. The accounting and estimation results could be used to give suggestions to increase water use efficiency and promote virtual water trade in the study area. Comparison of the proposed method with other prevailing method was also analyzed. The introduced method could be utilized for accounting and estimation of virtual water by sectors, with its superiority in characterizing industrial water consumption and the accounting results could lend certain credence to the water resource management and industrial transformation for the future economic development of northwest China.     

Dynamic simulation of hydrokinetic hammer based on virtual prototyping technology

This study presented the specified steps of comprehensively analyzing the hydraulic-driven hammer system with the application of the Virtual Prototype Technology. By comparing the simulation results with experimental phenomena and data, the correctness of simulation analysis conclusion is verified. Meanwhile, by -means of its perfect visualization, the internal work process which can not be seen before is simulated. The mechanism of some abnormal phenomena encountered during the experiment is explained.     

Virtual globes for UAV-based data integration: Sputnik GIS and Google Earth™ applications

The integration of local measurements and monitoring via global-scale Earth observations has become a new challenge in digital Earth science. The increasing accessibility and ease of use of virtual globes (VGs) represent primary advantages of this integration, and the digital Earth scientific community has adopted this technology as one of the main methods for disseminating the results of scientific studies. In this study, the best VG software for the dissemination and analysis of high-resolution UAV (Unmanned Aerial Vehicle) data is identified for global and continuous geographic scope support. The VGs Google Earth and Sputnik Geographic Information System (GIS) are selected and compared for this purpose. Google Earth is a free platform and one of the most widely used VGs, and one of its best features its ability to provide users with quality visual results. The proprietary software Sputnik GIS more closely approximates the analytical capacity of a traditional GIS and provides outstanding advantages, such as DEM overlapping and visualization for its dissemination.     

Evaluation of Surface Air Temperature Change over China and the Globe during the Twentieth Century in IAP AGCM4.0

Based on time series and linear trend analysis, the authors evaluated the performance of the fourth generation atmospheric general circulation model developed at the Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP AGCM4.0), in simulating surface air temperature (SAT) during the twentieth century over China and the globe. The numerical experiment is conducted by driving the model with the observed sea surface temperature and sea ice. It is shown that IAP AGCM4.0 can simulate the warming trend of the global SAT, with the major warming regions in the high latitudes of the Northern Hemisphere and the mid-latitudes of the Southern Hemisphere. While the simulated trend over the whole globe is close to the observation, the model under-estimates the observed trend over the continents. More-over, the model simulates the spatial distribution of SAT in China, with a bias of approximately-2°C in eastern China, but with a more serious bias in western China. Compared with the global mean, however, the correlation coefficient between the simulation and observation in China is significantly lower, indicating that there is large uncertainty in simulating regional climate change.