Coupling and comparing a spatially- and temporally-detailed eutrophication model with an ecosystem network model: An initial application to Chesapeake Bay

Coastal waters are modeled for a variety of purposes including eutrophication remediation and fisheries management. Combining these two approaches provides insights which are not available from either approach independently. Coupling is confounded, however, by differences in model formulations and “currencies.” We present here an initial coupling of a spatially- and temporally-detailed eutrophication model, CE-QUAL-ICM, with a network fisheries model, Ecopath. We list commonalities between the models and present algorithms and software for the exchange of information. The models are applied to the central portion of Chesapeake Bay for a contemporary summer period. After comparison of the representations of Chesapeake Bay by the two models, an illustrative example one-way, off-line, coupling is presented. In an initial examination of a 20% increase in predation on phytoplankton by a small, highly-exploited fish (Atlantic menhaden, Brevoortia tyrannus), computed reduction in phytoplankton biomass is accompanied by increased production due to enhanced nutrient recycling. Minimal impact on the structure of the food web or on biomass of higher-trophic level organisms is computed. The algorithms and software can be adapted to alternate eutrophication models and Ecopath applications and provide the first, necessary, steps for subsequent coupling with the time-variable Ecosim model.     

黄河信息资源共享服务系统设计与实现

为了有效组织和管理黄委局域网内各类分布异构的数据资源,解决在网络环境下的异构信息资源整合问题,促进信息共享与利用,开发建设了黄河信息资源共享服务系统。黄河信息资源具有内容形式复杂多样、异构、海量与分布式存储的特征,因此在系统的开发过程中,通过采用统一标准,引入基于语义的信息资源管理和信息服务机制,把本体的语义推理能力有效地与元数据信息相结合,从而建立语义统一的全局模式,达到屏蔽底层数据库异构现象的目的。该系统由应用系统、应用支撑平台、中心节点和分节点构成,具有数据汇交、查询浏览、数据下载、数据目录服务、用户管理和访问统计等功能。     

Multi-agent based path planning for first responders among moving obstacles

Natural or man-made disasters can cause different kinds of moving obstacles (e.g., fires, plumes, floods), which make some parts of the road network temporarily unavailable. After such incidents occur, responders have to go to different destinations to perform their tasks in the environment affected by the disaster. Therefore they need a path planner that is capable of dealing with such moving obstacles, as well as generating and coordinating their routes quickly and efficiently. In this paper, we present a novel approach for using a multi-agent system for navigating one or multiple responders to one or multiple destinations in the presence of moving obstacles. Our navigation system supports information collection from hazard simulations, spatio-temporal data processing and analysis, connection with a geo-database, and route generation in dynamic environments affected by disasters. We design and develop a set of software geospatial agents that assist emergency actors in dealing with the spatio-temporal data required for emergency navigation, based on their roles in the disaster response. One of the key components of the system is the path planning module, which combines the modified A* algorithm, insertion heuristics, and auction algorithm to calculate obstacle-avoiding routes for multiple responders with multiple destinations. A spatial data model is designed to support the storage of information about the tasks and routes produced during the disaster response. Our system has been validated using four navigation cases. Some preliminary results are presented in this paper and show the potential of the system for solving more navigation cases.     

基于IHA/RVA法的修水流域上游大型水库影响下的枯水变异研究

根据水文变异指标法及变化范围法(IHA/RVA),对江西修水流域上游两个大型水库启用日期差异进行组合,定量计算、分析了水利工程影响下的修水流域上游枯水流量的时序变异特征,探讨了水利工程建设前后导致的水文变异程度,揭示了对河流生态系统至关重要的低流量范围内多个枯水情势高改变度的存在,为水库生态调度与河流生态保护提供了有益的参考。     

State-sponsored and spontaneous urbanization in Fujian province of China, 1982–2010

This paper examines unbalanced urbanization process in Fujian province from 1982 to 2010 from the perspective of dual-track urbanization. The analysis is mainly based on 67 county-level units. The spontaneous track of urbanization is a new process of urbanization in China emerged in the reform period. It plays an important role in linking urban and rural areas but also creates problems of rural-urban integration and social cohesion. This paper examines the relative roles of spontaneous and state-sponsored urbanization and their impacts on the spatial pattern and structure of urbanization in Fujian. It is found that rural to urban migration plays the most significant role while state-sponsored urbanization and rural urbanization play equal roles in the process of urbanization. There was a significant shift of state-sponsored urbanization from county-level cities and counties to urban areas of central cities, Fuzhou and Xiamen, and from inland area to coastal area after 1990. There have also been significant shift and growth of temporary population towards the central cities in the reform period. The shift from small towns to large urban areas is clear in both tracks of urbanization.     

Understanding farmer cooperatives' self-inspection behavior to guarantee agri-product safety in China

Both global and domestic markets place increasing importance on the quality and safety of food products that are produced in China. The presence of microbial agents, toxic animal and plant products and chemical contamination remain because of the existence of small and dispersed farmers, who are not educated to use agricultural inputs correctly. This inability raises the issue of safety control in the agricultural sector. This study proposes that cooperatives' self-inspection of agricultural products before they enter the market can better organize small farmers to utilize a standardized production and safety management system. Therefore, we attempt to explore the factors that influence farmer cooperatives' self-inspection behavior. An Ordered Logistic Regression Model is employed to estimate the factors that influence cooperatives' choices of inspection frequency. The results show that the respondents expressed a medium to high level of implementing self-inspection but a lower level of concern in testing products by batch. The regression results indicate that subjective norms from the social environment, the perceived behavioral control of managers, ability and rules including input management, production documentation, and social demographic variables, significantly affect cooperatives' self-inspection behavior. The future implementation of safety inspection depends on the extent to which subjective norms, ability, and internal rules can improve agri-product safety in China.     

Mapping subsurface conditions within the near-shore zone of an Arctic delta using ground penetrating radar

This paper demonstrates the capabilities of ground penetrating radar (GPR) to map and resolve shallow subsurface features in the near-shore zone: (i) ice conditions (floating or bottom fast); (ii) water bathymetry; (iii) sedimentary structures; and (iv) interfaces between frozen and unfrozen sediment. These features were resolved in the near-shore zone of the Mackenzie Delta, N.W.T., Canada, using multi-frequency (50, 100 and 250 MHz) GPR data collected in winter (2005 and 2006). The capability of GPR to resolve subsurface features in the near-shore zone was strongly controlled by bottom-fast and floating ice conditions. The latter were discriminated using a novel approach involving the energy return from the base of ice and the presence of ice-bottom multiples. Beneath zones of bottom-fast ice, sedimentary structures and interfaces between frozen and unfrozen sediment were discriminated by reflection geometry and amplitude. Beneath floating ice, water depths were measured to depths greater than 5 m using a multi-layer depth calculation. Overall, this research demonstrates that baseline information for geotechnical investigations and climate change research in Arctic coastal zones can be greatly enhanced with GPR data.     

A method for analyzing pollution control policies: Application to SO2 emissions in China

Market-based pollution control mechanisms such as pollution levy and cap and trade have received increasing attention from both academics and practitioners. A good understanding of the optimal pollution price under these mechanisms is a premise for regulators to make sound pollution control policies. In this paper, we propose a method for deriving the optimal pollution price for a given pollution target. This method consists of two steps that integrate cost function estimation and market equilibrium analysis: First, historical data is used to estimate the pollution abatement cost functions of the polluters; second, market models are used to solve the equilibrium pollution price under each control mechanism. For illustration, we apply the method to investigate SO₂ emission control policies in China, using a dataset of SO₂ emissions and abatement costs from three major industry sectors (Electricity, Gas, and Water Supply; Manufacturing; and Mining). Our analysis shows that the optimal levy rate is significantly higher than the actual rate adopted by the Chinese government. For example, the optimal levy rate should be 4.92 RMB/kg, while the actual rate is 1.26 RMB/kg in 2010. As a result, the actual emission structure is much less efficient: The overall cost savings would be 49.7% for all three sectors during 2006–2010 if the optimal emission structure is achieved. These findings have useful policy implications for the Chinese government. In addition, the method may be applied to analyze control policies at different aggregate levels (for example, provincial economies) or for other pollutants (for example, CO₂ and chemical oxygen demand).     

Urban form breeds neighborhood vibrancy: A case study using a GPS-based activity survey in suburban Beijing

In this paper, we present a formal analysis of the neighborhood vibrancy created by urban form. We use Geographic Information Systems (GIS) to develop quantitative measures of urban form and define neighborhood vibrancy based on a GPS-based activity survey in suburban Beijing. An Urban Form index was adopted to determine that our measures of urban form capture meaningful differences in the characteristics of urban neighborhoods – differences that may have direct impacts on neighborhood vibrancy. Specifically, high density and mixed land use are strongly positively correlated with neighborhood vibrancy, whereas developed external traffic systems are negative. However, a thorough inter-circulation system and convenient accessibility do not always boost neighborhood vibrancy. These factors lose efficacy when gated neighborhoods are selected and surrounding facilities are distributed far away. Our study argues that urban planners, using their professional judgment, can contribute to urban vitality at the neighborhood scale.     

Comparison of Radiometric Quality of GF-1 Satellite Image in Snow-covered Area of Manasi River Basin

Radiometric quality of satellite’s image is closely related to its monitoring capability.GF-1 is the first satellite of China’s high-resolution earth observation system and has an important application value in monitoring mountain snow.In this paper,we compare the radiometric quality of GF-1 satellite image to the similar overseas high-resolution satellite SPOT-6 and RapidEye in snow-covered area of Manasi River Basin.The results could provide some advices for future GF series satellites’ development in China.Using the image statistical features,average gradient,information entropy,and SNR,the radiometric quality of the three satellite images is compared.The results show that the GF-1’s image statistical features and average gradient has the best performance.However,the information entropy has a certain gap compared with the other two satellites due to the depth of radiation.GF-1 partially supersaturated during snow imaging,resulting in part of region having zero value.After removing these outliers,GF-1 image’s SNR is re-estimated and found to be significantly superior to other satellites in the blue,red,and panchromatic bands,whereas,the green and near-infrared bands still have a certain gap compared to SPOT-6,but similar to RapidEye.Overall,the radiometric quality of GF-1 image in the mountainous snow-covered area has basically reached the level of similar satellites in the world and some indicators are even better than other satellite images.Limited to the depth of radiation and the range of radiation energy accepted by the sensor,an over-saturation phenomenon will appear in some snow-covered regions,the follow-up can be further improved in this regard.