A Vector-based Cellular Automata Model for Simulating Urban Land Use Change

Cellular Automata(CA) is widely used for the simulation of land use changes. This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditional raster-based CA model. The cells of vector-based CA model are presented according to the shapes and attributes of geographic entities, and the transition rules of vector-based CA model are improved by taking spatial variables of the study area into consideration. The vector-based CA model is applied to simulate land use changes in downtown of Qidong City, Jiangsu Province, China and its validation is confirmed by the methods of visual assessment and spatial accuracy. The simulation result of vector-based CA model reveals that nearly 75% of newly increased urban cells are located in the northwest and southwest parts of the study area from 2002 to 2007, which is in consistent with real land use map. In addition, the simulation results of the vector-based and raster-based CA models are compared to real land use data and their spatial accuracies are found to be 84.0% and 81.9%, respectively. In conclusion, results from this study indicate that the vector-based CA model is a practical and applicable method for the simulation of urbanization processes.     

Integrated data processing method for GPS and INS field test over Rocky Mountain

IntroductionGPS/INS integrated system exploited the INSand differential GPS pseudo-range and carrierphase technique to promote the accuracy of thedynamic platform navigation and positioning,and increase the reliability and stabilization.Incalculation, Kal…     

Origin and Distribution of Grain Dolostone Reservoirs in the Cambrian Longwangmiao Formation, Sichuan Basin, China

Dolostones in the Cambrian Longwangmiao Formation have become one of the most significant gas exploration domains in China. Over a trillion cubic meters of gas reservoirs have been discovered in the Gaoshiti-Moxi area; however, the origins and distribution of the dolostone reservoirs are not well understood. This work discussed the geology and geochemistry of the dolostone reservoirs in the Longwangmiao Formation to determine their origin and distribution. Two understandings are acquired: firstly, a carbonate ramp provided excellent conditions for grain beach deposition, while the presence of a hypersaline lake was favorable for the contemporaneous dolomitization of grain beach deposits. Petrographic and geochemical evidence further confirm that the Longwangmiao dolostone was formed during the contemporaneous stage. Secondly, the reservoir characteristics indicate that the grain beach sediments provide material basis for the development of the Longwangmiao dolostone reservoirs. Reservoir dissolution simulation experiments show that the porosity of the reservoirs was formed by dissolution during contemporaneous and burial stages. The dissolution pores formed during the contemporaneous stage were controlled by sequence interfaces. The large scale dissolution vugs formed during the burial stage subsequently spread along the pre-existing porosity and fracture zones. This study therefore identified that the development of grain dolostone reservoirs in a shallow water ramp under arid climatic conditions generally met the following conditions: (1) reefal beach deposits lay a foundation for reservoir development; (2) superficial conditions are an important determining factor for reservoir porosity; and (3) burial conditions provide environment for porosity preservation and modification.     

Parameter regionalization of the FLEX-Global hydrological model

Global hydrological models(GHMs) are important tools for addressing worldwide change-related water resource problems from a global perspective. However, the development of these models has long been hindered by their low accuracy. In order to improve the streamflow simulation accuracy of GHMs, we developed a GHM—the FLEX-Global—based on the regionalization of hydrological model parameters. The FLEX-Global model is primarily based on the framework of the FLEX hydrological model coupled with the HAND-based Storage Capacity curve(HSC) runoff generation module to calculate net rainfall, and uses the global river-routing Ca Ma-Flood model to calculate river network routing. This new model allows for streamflow simulation at a spatial resolution of 0.5°×0.5° and a temporal resolution of 1 day in global catchments. To validate FLEX-Global accuracy, the FLEX-Global-simulated streamflow of 26 major rivers distributed in five different climate zones was compared with the observed data from the Global Runoff Data Center(GRDC). Next, the model performance of FLEXGlobal was further verified by comparing it with that of seven existing GHMs with varying accuracy in the five climate zones.Multi-metric evaluation indicated that the streamflow simulation accuracy was improved by the FLEX-Global model with regionalized parameters, especially in the tropical and dry climate zones. This newly-developed GHM with regionalized parameters can provide scientific support for the assessment of climate change impact, optimization of global water resource mangement, simulation of Earth's multi-sphere coupling, and implementation of the Inter-Sectoral Impact Model Intercomparison Project(ISIMIP).     

Investigation of Controlling Factors for Growth in Stromatolites of the Tieling Formation, Jixian, Tianjin

<正>Objective The Yan–Liao Aulacogen is located in the northern SinoKorean Plate,buried under huge Meso–Neoproterozoic sedimentation,and is widely distributed in Beijing,Tianjin and Hebei.In these strata,several microbial mats occur,represented by four stromatolite assemblages within the Upper Precambrian stratotype section at Jixian,Tianjin.     

New Discoveries of the Influence of Sedimentary Environment on Rearranged Hopanes in Source Rocks

<正>Objective The distribution of rearranged hopanes in hydrocarbon source rocks is influenced by thermal maturity and original source input,and is also controlled by depositional conditions.Through comparison of lacustrine and coal-bearing source rocks,this work attempted to analyze the composition and origin of rearranged hopanes in hydrocarbon source rocks.Taken the source rocks from     

Observations and Research on the Solar Radio Spectrum at Yunnan Observatory

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Reducing Influence of Gravity Model Error in Precise Orbit Determination of Low Earth Orbit Satellites

Based on the orbit integration and orbit fitting method, the influence of the characters of the gravity model, with different precisions, on the movement of low Earth orbit satellites was studied. The way and the effect of absorbing the influence of gravity model error on CHAMP and GRACE satellite orbits, using linear and periodical empirical acceleration models and the so-called "pseudo-stochastic pulses" model, were also analyzed.     

The multi-scale numerical modeling system for research on the relationship between urban planning and meteorological environment

Considering the urban characteristics, a customized multi-scale numerical modeling system is established to simulate the urban meteorological environment.THE system mainly involves three spatial scales;the urban scale, urban sub-domain scale, and single to few buildings scale. In it, different underlying surface types are employed, the building drag factor is used to replace its roughness in the influence on the urban wind field, the effects of building distribution, azimuth and screening of shortwave radiation are added, and the influence of anthropogenic heating is also taken into account. All the numerical tests indicate that the simulated results are reasonably in agreement with the observational data, so the system can be used to simulate the urban meteorological environment. Making use of it, the characteristics of the meteorological environment from the urban to urban sub-domain scales, even the among-buildings scale,can be recognized. As long as the urban planning scheme is given, the corresponding simulated results can be obtained so as to meet the need of optimizing urban planning.     

Spatio-temporal prediction of regional land subsidence via ConvLSTM

Land subsidence is a geohazard phenomenon caused by the lowering of land elevation due to the compression of the sinking land soil body, thus creating an excessive constraint on the safe construction and sustainable development of cities. The use of accurate and efficient means for land subsidence prediction is of remarkable importance for preventing land subsidence and ensuring urban safety. Although the current time-series prediction method can accomplish relatively high accuracy, the predicte...