Unmanned aerial vehicle (UAV) low-altitude remote sensing technology has recently been adopted in China. However, mapping accuracy and production processes of true digital orthophoto maps (TDOMs) generated by UAV images require further improvement. In this study, ground control points were distributed collected using a multi-rotor professional camera, at flight height 160 m above the designed sample distance (GSD) 0.016 m. A structure from motion (SfM), revised surface model (DSM) multi-view...

Urban construction land-use expansion is an important topic in the field of change research. In present study, temporal and spatial changes urban land use Chongqing area are analyzed, based on maps from 1975, 1987, 1995, 2000, 2010. Using gradient analysis, study was divided into nine buffer zones eight quadrants. The analyzed compactness different ranges directions, further fitted degrees gradients. results indicated that there a rapid growth period 2000–2010, for sharply increased at...

Abstract The reasonable layout of green infrastructure is conducive to the low-carbon, livable and high-quality sustainable development cities. framework spatio-temporal evolution characteristics prediction analysis Urban Green Infrastructure (UGI) was constructed by integrating morphological spatial pattern (MSPA) CA-Markov in study. We analyzed UGI Beijing from 1990 2019, predicted its future change trend 2030, put forward optimization scheme for ecological network UGI. area presented a...

In the study of spatiotemporal geographical phenomena, space–time interpolation method is widely applied, and demands for computing speed accuracy are increasing. For nonprofessional modelers, utilizing quickly a challenge. To solve this problem, classical ordinary kriging algorithm was selected expanded to algorithm. Using OpenCL framework integrate central processing unit (CPU) graphic (GPU) resources, parallel implemented, three experiments were conducted in work verify results. The...

Robust and real-time condition monitoring of the underground gas distribution network (ca. 3000 km) in Singapore is critical for interruption-free power generation. For this purpose, paper, we investigate optical techniques, based on distributed fiber optic sensors, recently proposed context pipeline monitoring. A detailed review these techniques their applications terms sensing range, spatial, temperature strain resolutions has been generalized. During leaks, Joule-Thomson (JT) cooling...

Water ingress problem caused by gas leaks in distribution pipeline is a rather thorny problem, which the companies typically encounter. Replacing existing faulty costly and troublesome. For pipelines, when leak happens, escapes from pipelines into free space or surrounding environment, results cooling of nearby area due to Joule-Thomson effect. Commercial distributed temperature sensing (DTS) system with appropriate operation method could be solution as it can achieve resolution 0.05°C. The...

The quantitative calculation of emulsified water fractions crude oil–water systems is great significance for the study flow characteristics multiphase pipelines. For a system with high fraction, fraction under different influencing factors was determined by emulsification experiments. It found that shearing conditions correlated well exergy loss rate and could be described power-law equation, in which two undetermined parameters relate to oil physicochemical properties. Six representative...

摘要： 压缩天然气的海上运输技术由于其经济效益而即将走向商业化。在运输船上的压强高达25 MPa的压力容器是其设计的重点。破前漏准则是维护压力容器完整性的一个重要方法。然而,在压力容器泄漏中发生的焦耳-汤姆逊效应所导致的裂纹周围金属温度的降温可能会影响到破前漏准则的有效性。对在压力容器的泄漏中发生的焦耳-汤姆逊效应做了相关的试验研究。因氩气不易燃烧且具有与甲烷相似的焦耳-汤姆逊系数而被选作试验气体。设计一个全新的用于压力容器泄漏试验的焦耳-汤姆逊测试系统。根据美国机械工程师学会(American Society of Mechanical Engineers, ASME)锅炉和压力容器规范设计和加工一个试验用的压力容器。采用液氮断裂方法在一块测试板上制作一个与自然裂纹相似的贯穿裂纹。在30 ℃的环境温度和9.1 MPa的最大内部压强下,测试板外表面沿裂纹方向测得的最低温度是12.5 ℃,沿裂纹对角线方向测得的最低温度是7.9 ℃,裂纹出口处得到的氩气的温度是-9.2 ℃;测试板内表面沿裂纹方向测得的最低温度是15 ℃,容器内部裂纹附近测得的氩气的温度是-7.1...

The cooling effect caused by the Joule-Thomson (JT) in leakage of pressure vessels has gained more and attention worries from natural gas transportation industries as it may influence validity conventional leak-before-break approach. Currently, (LBB) design codes for do not take into account subsequent low temperature depression drop fracture toughness aftermath a leak. This study is to ensure integrity compressed (CNG) containment marine being proposed transport highly pressurized (up 250...

The Yunshui Cave in Shangfang Mountain, Beijing, is a famous high-altitude karst cave northern China. As the third scientific survey of history, this first time to use latest LiDAR technology carry out related detection survey. Traditional measurement methods are limited by natural conditions and make it difficult reach destination. mainly rely on experience obtain data with strong subjectivity, making conduct quantitative research reproducible results current information era. Applying can...

The model environment is a key component that enables virtual geographic (VGE) to meet the scientific requirements for simulating dynamic phenomena and performing analyses. Considering comprehensiveness of processes replication model-based research, this paper proposes base framework VGE supports both construction modelling management, resulting in improved reproducibility. In framework, management includes metadata, creation, deposition, encapsulation, integration, adaptation; while focuses...

The advantage of the new compressed natural gas (CNG) marine transportation technology is less investment in infrastructure and greater flexibility. It highly competitive as compared to pipelines liquefied (LNG) transport for distances up 2,500 – 3,000 nautical miles. Due high pressure inside CNG containers, its safety first important factor be considered. Leak-before-break (LBB) an methodology maintaining integrity vessels. However, Joule-Thomson (JT) cooling effect occurred during a leak...

Suburbanization is an inevitable phenomenon during urbanization process at home and abroad. More more attention also paid to suburbanization issue in China as carries on. Unfortunately, the role of FDI important driving force urban renewal new district development configuration shape space has been neglected by current literature. Based on theoretical hypothesis mono-centric city, this paper incorporates into analytical framework suburbanization, constructs sprawl indexes municipal area...

Using airborne light detection and ranging (LiDAR) point cloud data for building reconstruction, is widely used in urban construction, planning dynamic monitoring, etc.So far, it still difficult to applied rapid modeling large areas.In this study, based on the GIS platform, with utilization of scale digital line graph (DLG) combined LiDAR data, a method established.The basic idea segment through histogram threshold analysis DTM test, then extract elevation from by use DLG, finally build 3D...

As the localized temperature drop induced by Joule-Thomson cooling effect in a leak causes reduction fracture toughness at crack front, leak-before-break approach that does not take this into account may be unconservative. In paper, argon was selected as experimental gas used experiment due to its incombustibility and similar coefficient of methane. An pressure vessel with design 250 bar designed fabricated. Liquid nitrogen cracking method employed fabricate realistic through-thickness test...

At present, most of the commercial 3D laser scanning measurement systems do work for a large area and big scene, but few shows their advantage in small or scene. In order to solve this shortage, we design light-small mobile system, which integrates GPS, INS, scanner digital camera other sensors, generate Point Cloud data target through filtering fusion. This system can be mounted on airborne terrestrial platform enables achieve goal getting rapidly reconstructing real model. Compared...