Research on storing raster metadata in spatial database

Storage of raster metadata is a key topic in spatial database. Although there are a few of abstract standards on raster metadata, there is not implement standard about it. This paper concludes three storage models implemented in current spatial databases and discusses their advantages and disadvantages. After that analyzing, the paper proposes a mixed storage method which is used the relational table to store structured metadata and used XML to store non-structured metadata, and gives its implementation solution. © 2010 IEEE.

浅论实现基于MapX的灌溉信息系统的关键技术

现代化的灌溉用水管理是实现农业高效用水的重要措施之一,它可实现灌溉水资源的合理配置和灌溉系统的优化调度,达到节水增产目的,使有限的水资源获得最大的效益。采用手工方式进行灌溉用水管理,难以及时提供水资源利用最优化方案,因此急需研制出具有网络通信功能的可视化操作界面的灌溉信息管理系统,为灌区水资源评价和利用、规划等工作奠定良好的数据基础。GIS不仅具有强大的空间数据管理功能,还具有丰富的多元地学数据分析处理能力和直观的图形显示效果,因此利用GIS进行灌区的管理与建设将会有效提高灌区的工作效率和经济效益。笔者在实践调研的基础上,根据灌溉信息管理系统的功能规划及结构设计,利用MapX组件工具开发了陕西省冯家山灌区灌溉信息系统,对提高灌溉用水的管理效率进行了实例尝试,并着重对下列关键技术的运用进行了实践与思考:(1)阐述了利用可视化编程工具结合数据库管理技术、地理信息系统组件技术、网络通信技术等进行系统开发的过程;(2)着重介绍了基于MapX组件的空间数据库的建立与关联技术、灌溉管理信息的网络通信实现技术;(3)最后对在灌溉管理工作中运用GIS技术进行科学管理等相关问题进行了有益的探讨。

基于Geodatabase和Arcengine的海岛空间数据库的设计与实现

本文对山东省海岛进行了研究，认识了山东省不同地区海岛的自然环境、资源和开发利用的总体状况。通过对大量的海岛调查资料的整理、分析，提出了利用Geodatabase数据模型构建山东省海岛空间数据库来组织和存储海岛数据的方案，采用GIS软件平台ArcEngine和程序开发语言研发山东省海岛管理信息系统。 山东省是我国海岛资源比较丰富的省份。从整体来看，山东省海岛地理位置优越，气候条件好，海岛类型分为基岩岛、沙岛和人工岛，其中大部分海岛为基岩岛，沙岛主要分布在黄河三角洲北侧的滨州和潍坊昌邑。山东省海岛拥有丰富的渔业资源、水产资源、旅游资源、土地资源、港口资源、地下卤水资源、贝壳砂资源等，依据这些资源优势，海岛的开发也集中在养殖业开发、旅游开发、港口资源开发等。 Geodatabase数据模型能够有效地定义、组织空间数据，ArcSDE技术提供了空间数据存储在商业关系型数据库的通道，Geodatabase数据模型和ArcSDE技术使得使用同一大型的关系型数据库统一存储空间数据和属性数据成为可能。本文采用Geodatabase数据模型、ArcSDE技术、SQL Server数据库，设计了海岛数据的统一存储和管理模型，通过数据处理和入库建立了山东省海岛空间数据库。 本文还基于GIS软件平台ArcEngine组件和程序开发语言VB.NET完成了山东省海岛管理信息系统的开发。该系统实现了海岛数据的访问和加载、海岛地图的显示和操作、海岛数据的多种方式的查询显示、地图的几何量算功能以及海岛专题资料的集成与综合分析，同时系统也提供数据图层的标注、图层颜色的设置，图层的移动、删除功能。这些功能的实现对山东省海岛的开发、管理提供了有用的平台，为决策部门提供服务。

基于GIS的高速公路养护管理信息系统的设计与开发

China is experiencing a rapid development of highway ever since 1990s. By the end of 2004, the total length of the highway summed up to 33 thousand kilometers, ranking 2n in the world. After the open of highway, the accumulation of time and traffic causes the decrease of its capability. To ensure its good quality, security and operation functions, we should take some reasonable measures to maintain it periodically. At present, a big problem is that the traditional maintain measures can no longer meet the increasing requirements. Due to the characters of highway, the relationship of various maintenance data and geographic positions is even closer than any others. If we wan to improve the quality and efficiency of the maintenance work, particularly when there is need for decision-making, a great number of data that is related to geographic positions are absolutely necessary. Evidently, Geographical Information System (GIS) has incomparably advantages in dealing with these spatial information. As a result, a management system for highway maintenance work based on GIS became inevitable for the development of the maintenance of highway. The purpose of this paper is to establish a management system for highway maintenance work base on Geographical Information System (GIS), Global Positioning System (GPS) and spatial database, to manage all kinds of problems encountered in the work, and to provide support on information and methods. My study mainly includes: (1) Analysis on the current status of the maintenance and management work; overview on the history of domestic and international highway maintenance management systems; identifying the necessity and importance for establishing a management system for highway maintenance work based on GIS. (2) Based on the requirement analysis, I proposed a general design for this management system, and discussed the objective, design principles, framework, systematical structure and function design. (3) Outdoor data collection is not only a prime way to understand the current situation of the road, but also an important method for data update after the system is put into use. This paper also intends to establish a set of plan to collect data efficiently and precisely which is based on GIS and GPS technologies. (4) The maintenance management database is a supporting platform for various maintenance decision-makings. Such decisions need the support of a great amount of data, which would cause other problems, such as the diversity of the data source, difference of data formats. This paper also discussed how to deal with these problems and establish such a database. (5) To propose an approach to assess the condition of pavement, based on GIS and related maintenance models. Among all the maintenance models, the two for assessing and forecasting pavement condition are the most important and mature. This paper also analyzed these two models and introduced them in terms of the integration of models. (6) This paper took the Guangshen Highway for example, explaining how to realize a GIS for management of highway maintenance work.

STUDY ON THE SPATIAL PATTERNS OF LAND-USE CHANGE AND ANALYSES OF DRIVING FORCES IN NORTHEASTERN CHINA DURING 1990-2000

Land-use change is an important aspect of global environment change. It is, in a sense, the direct result of human activities influencing our physical environment. Supported by the dynamic serving system of national resources, including both the environment database and GIS technology, this paper analyzed the land-use change in northeastern China in the past ten years (1990 - 2000). It divides northeastern China into five land-use zones based on the dynamic degree (DD) of land-use: woodland/grassland - arable land conversion zone, dry land - paddy field conversion zone, urban expansion zone, interlocked zone of farming and pasturing, and reclamation and abandoned zone. In the past ten years, land-use change of northeastern China can be generalized as follows: increase of cropland area was obvious, paddy field and dry land increased by 74. 9 and 276. 0 thousand ha respectively; urban area expanded rapidly, area of town and rural residence increased by 76. 8 thousand ha; area of forest and grassland decreased sharply with the amount of 1399. 0 and 1521. 3 thousand ha respectively; area of water body and unused land increased by 148. 4 and 513. 9 thousand ha respectively. Besides a comprehensive analysis of the spatial patterns of land use, this paper also discusses the driving forces in each land-use dynamic zones. The study shows that some key biophysical factors affect conspicuously the conversion of different land- use types. In this paper, the relationships between land- use conversion and DEM, accnmlated temperature(>= 10 degrees C) and precipitation were analysed and represented. We conclude that the land- use changes in northeast China resulted from the change of macro social and economic factors and local physical elements. Rapid population growth and management changes, in some sense, can explain the shaping of woodland/grassland - cropland conversion zone. The conversion from dry land to paddy field in the dry land - paddy field conversion zone, apart from the physical elements change promoting the expansion of paddy field, results from two reasons: one is that the implementation of market-economy in China has given farmers the right to decide what they plant and how they plant their crops, the other factor is originated partially from the change of dietary habit with the social and economic development. The conversion from paddy field to dry land is caused primarily by the shortfall of irrigation water, which in turn is caused by poor water allocation managed by local governments. The shaping of the reclamation and abandoned zone is partially due to the lack of environment protection consciousness among pioneer settlers. The reason for the conversion from grassland to cropland is the relatively higher profits of fanning than that of pasturing in the interlocked zone of farming and pasturing. In northeastern China, the rapid expansion of built-up areas results from two factors: the first is its small number of towns; the second comes from the huge potential for expansion of existing towns and cities. It is noticeable that urban expansion in the northeastern China is characterized by gentle topographic relief and low population density. Physiognomy, transportation and economy exert great influences on the urban expansion.

NDVI spatial pattern and its differentiation on the Mongolian Plateau

GIMMS NDVI database and geo-statistics were used to depict the spatial distribution and temporal stability of NDVI on the Mongolian Plateau. The results demonstrated that: (1) Regions of interest with high NDVI indices were distributed primarily in forested mountainous regions of the east and the north, areas with low NDVI indices were primarily distributed in the Gobi desert regions of the west and the southwest, and areas with moderate NDVI values were mainly distributed in a middle steppe strap from northwest to southeast. (2) The maximum NDVI values maintained for the past 22 years showed little variation. The average NDVI variance coefficient for the 22-year period was 15.2%. (3) NDVI distribution and vegetation cover showed spatial autocorrelations on a global scale. NDVI patterns from the vegetation cover also demonstrated anisotropy; a higher positive spatial correlation was indicated in a NW-SE direction, which suggested that vegetation cover in a NW-SE direction maintained increased integrity, and vegetation assemblage was mainly distributed in the same specific direction. (4) The NDVI spatial distribution was mainly controlled by structural factors, 88.7% of the total spatial variation was influenced by structural and 11.3% by random factors. And the global autocorrelation distance was 1178 km, and the average vegetation patch length (NW-SE) to width (NE-SW) ratio was approximately 2.4:1.0.

Thermal fatigue on pistons induced by shaped high power laser. Part II: Design of spatial intensity distribution via numerical simulation

In the laser induced thermal fatigue simulation test on pistons, the high power laser was transformed from the incident Gaussian beam into a concentric multi-circular pattern with specific intensity ratio. The spatial intensity distribution of the shaped beam, which determines the temperature field in the piston, must be designed before a diffractive optical element (DOE) can be manufactured. In this paper, a reverse method based on finite element model (FEM) was proposed to design the intensity distribution in order to simulate the thermal loadings on pistons. Temperature fields were obtained by solving a transient three-dimensional heat conduction equation with convective boundary conditions at the surfaces of the piston workpiece. The numerical model then was validated by approaching the computational results to the experimental data. During the process, some important parameters including laser absorptivity, convective heat transfer coefficient, thermal conductivity and Biot number were also validated. Then, optimization procedure was processed to find favorable spatial intensity distribution for the shaped beam, with the aid of the validated FEM. The analysis shows that the reverse method incorporated with numerical simulation can reduce design cycle and design expense efficiently. This method can serve as a kind of virtual experimental vehicle as well, which makes the thermal fatigue simulation test more controllable and predictable. (C) 2007 Elsevier Ltd. All rights reserved.

The vector fields admitting one-parameter spatial symmetry group and their reduction

For a n-dimensional vector fields preserving some n-form, the following conclusion is reached by the method of Lie group. That is, if it admits an one-parameter, n-form preserving symmetry group, a transformation independent of the vector field is constructed explicitly, which can reduce not only dimesion of the vector field by one, but also make the reduced vector field preserve the corresponding ( n - 1)-form. In partic ular, while n = 3, an important result can be directly got which is given by Me,ie and Wiggins in 1994.

Numerical analysis of spatial evolution of the small signal gain in a chemical oxygen-iodine laser operating without primary buffer gas

A chemical oxygen iodine laser (COIL) that operates without primary buffer gas has become a new way of facilitating the compact integration of laser systems. To clarify the properties of spatial gain distribution, three-dimensional (3-D) computational fluid dynamics (CFD) technology was used to study the mixing and reactive flow in a COIL nozzle with an interleaving jet configuration in the supersonic section. The results show that the molecular iodine fraction in the secondary flow has a notable effect on the spatial distribution of the small signal gain. The rich iodine condition produces some negative gain regions along the jet trajectory, while the lean iodine condition slows down the development of the gain in the streamwise direction. It is also found that the new configuration of an interleaving jet helps form a reasonable gain field under appropriate operation conditions. (c) 2007 Elsevier Ltd. All rights reserved.

Spatial and Temporal Variation of LURR and Its Implication for the Tendency of Earthquake Occurrence in Southern California

Based on the theory of LURR and its recent development, spatial and temporal variation of Y/Y-c (value of LURR/critical value of LURR) in the Southern California region during the period from 1980 through March, 2001 was studied. According to the previous study on the fault system and stress field in Southern California, we zoned the Southern California region into 11 parts in each of which the stress field is almost uniform. With the time window of one year, time moving step of three months, space window of a circle region with a radius of 100 km and space moving step of 0.25 degree in latitude and longitude direction, the evolution of Y/Y-c were snapshot. The scanning results show that obvious Y/Y-c anomalies occurred before 5/6 of strong earthquakes considered with a magnitude of 6.5 or greater. The critical regions of Y/Y-c are near the epicenters of the strong earthquakes and the Y/Y-c anomalies occur months to years prior to the earthquakes. The tendency of earthquake occurrence in the California region is briefly discussed on the basis of the examination of Y/Y-c.

Assessment of bursting detection methods with LES database of turbulent channel flows

Validated by comparison with DNS, numerical database of turbulent channel flows is yielded by Large Eddy Simulation (LES). Three conventional techniques: uv quadrant 2, VITA and mu-level techniques for detecting turbulent bursts are applied to the identification of turbulent bursts. With a grouping parameter introduced by Bogard & Tiedemann (1986) or Luchik & Tiederman (1987), multiple ejections detected by these techniques which originate from a single burst can be grouped into a single-burst event. The results are compared with experimental results, showing that all techniques yield reasonable average burst period. However, uv quadrant 2 and mu-level are found to be superior to VITA in having large threshold-independent range.

An ultra-broadband spatially dispersed regenerative amplifier free from spatial chirp

An ultra-broadband Ti:sapphire regenerative amplifier based on spatially dispersed amplification is demonstrated experimentally. Departing from previous reports, a new design of the cavity gets the amplified pulse free from spatial chirp. Utilizing this new regenerative amplifier, chirped pulses with bandwidth (FWHM) of about 80 nm are obtained, and the bandwidth is limited only by that of the incident seed pulses.

Spatial longitudinal coherence length of a thermal source and its influence on lensless ghost imaging

The spatial longitudinal coherence length (SLCL), which is determined by the size of and the distance from the source, is introduced to investigate the longitudinal resolution of lensless ghost imaging. Its influence is discussed quantitatively by simulation. The discrepancy of position sensitivity between Scareelli et al. [Appl. Phys. Lett. 88, 061106 (2006)] and Basano and Ottonello [Appl. Phys. Lett. 88, 091109 (2006)] is clarified. (C) 2008 Optical Society of America.