Peng J.,Peking University |
Zong M.,Peking University |
Zong M.,Shanghai Urban Planning and Design Research Institute |
Hu Y.,Peking University |
And 2 more authors.
Sustainability (Switzerland) | Year: 2015
Landscape ecological risk assessment can effectively identify key elements for landscape sustainability, which directly improves human wellbeing. However, previous research has tended to apply risk probability, measured by overlaying landscape metrics to evaluate risk, generally lacking a quantitative assessment of loss and uncertainty of risk. This study, taking Liaoyuan City as a case area, explores landscape ecological risk assessment associated with mining cities, based on probability of risk and potential ecological loss. The assessment results show landscape ecological risk is lower in highly urbanized areas than those rural areas, suggesting that not only cities but also natural and semi-natural areas contribute to overall landscape-scale ecological risk. Our comparison of potential ecological risk in 58 watersheds in the region shows that ecological loss are moderate or high in the 10 high-risk watersheds. The 35 moderate-risk watersheds contain a large proportion of farmland, and the 13 low-risk watersheds are mainly distributed in flat terrain areas. Our uncertainty analyses result in a close range between simulated and calculated values, suggesting that our model is generally applicable. Our analysis has good potential in the fields of resource development, landscape planning and ecological restoration, and provides a quantitative method for achieving landscape sustainability in a mining city. © 2015 by the author; licensee MDPI, Basel, Switzerland.
Xiao J.,Shanghai JiaoTong University |
Gao X.,Shanghai Urban Planning and Design Research Institute |
Kong Q.-J.,Shanghai JiaoTong University |
Liu Y.,Shanghai JiaoTong University
Journal of Advanced Transportation | Year: 2014
This paper presents a multiple kernel support vector machine (MKL-SVM) ensemble algorithm to detect traffic incidents. It uses resampling technology to generate training set, test set, and training subset firstly; then uses different training subsets to train individual MKL-SVM classifiers; and finally introduces ensemble methods to construct MKL-SVM ensemble to detect traffic incidents. Extensive experiments have been performed to evaluate the performances of the four algorithms: standard SVM, SVM ensemble, MKL-SVM, and the proposed algorithm (MKL-SVM ensemble). The experimental results show that the proposed algorithm has the best comprehensive performances in traffic incidents detection. To achieve better performances, the proposed algorithm needs less individual classifiers to construct the ensemble than SVM ensemble algorithm. Thus, compared with SVM ensemble algorithm, the complexity of the ensemble classifier of the proposed algorithm is reduced greatly. Conveniently, the proposed algorithm also avoids the burden of selecting the appropriate kernel function and parameters. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.
Guo Y.,Tsinghua University |
Guo Y.,Shanghai Urban Planning and Design Research Institute |
Jia H.,Tsinghua University
Frontiers of Environmental Science and Engineering in China | Year: 2012
To improve the management of discharge pollutants loads in the reservoirs' watershed, an approach of the allowable pollutants loads calculation and its allocation, based on the water environment model, was proposed. Establishment of the approach framework was described at first. Under the guidance of this framework, two major steps were as follows: modeling and scenario analysis were involved and should be applied to support the decision of discharge loads management; Environmental Fluid Dynamic Code (EFDC) model was selected as the kernel model in this framework. In modeling step, spatial discretization for establishing cell map in model, data preprocessing, parameter calibration and uncertainty analysis (which is considered as the significantly relevant factor of the margin of safety (MOS)), were conducted. As a result of the research, the model-based approach presented as a combination of estimation and precise calculation, which contributed to scenario analysis step. Some integrated modules, such as scenario simulation, result analysis and plan optimization were implemented as cycles in the scenario analysis. Finally, allowable pollutant loads under various conditions were calculated. The Chaihe Reservoir in Liaoning Province, China was used as a case study for an application of the approach described above. Results of the Chaihe reservoir water quality simulation, show good agreement with field data and demonstrated that the approach used in the present study provide an efficient and appropriate methodology for pollutant load allocation. © 2012 Higher Education Press and Springer-Verlag Berlin Heidelberg.
Wang X.,Tongji University |
Jin Y.,Shanghai Urban Planning and Design Research Institute |
Abdel-Aty M.,University of Central Florida |
Tremont P.,Tongji University |
Chen X.,Tongji University
Transportation Research Record | Year: 2012
Traffic safety is beginning to receive increasing attention at the stage of transportation planning. Although the features of road networks are an essential aspect of transportation planning, studies of the safety effects of network patterns remain limited. In this study, macrolevel safety models were developed to explore the relationship between crash occurrence and several underlying variables, including demographic, land use, and road network variables. Different indices (e.g., the meshedness coefficient and closeness centrality) of network structures were developed to examine the effects of the network structure on safety at the zonal level. In many cases, a large percentage of the crash locations (especially for arterial crashes) was not related to the traffic analysis zones (TAZs) where drivers lived. To link crashes and features properly at the zonal level, crashes of each TAZ were modeled separately for non-state-maintained arterials (i.e., off-system roadways) and state-maintained arterials (i.e., on-system roadways). Several conditional autoregressive Bayesian models that incorporated the spatial correlation of nearby zones were developed. Estimation results showed that crashes occurring on non-state-maintained roads correlated more closely with the zonal network structure and the demographic characteristics inside the TAZ than did crashes occurring on state-maintained arterials; crashes on state-maintained arterials correlated more closely with the traffic and features of the major roads. The categorical variable generated from the meshedness coefficient captured well the nature of the relationship of network patterns to off-system road crashes. The results of this study indicate that both the roadway type and the structure of the road network should be considered when TAZ-level safety models are developed.
Zhou X.,Tongji University |
Zhou X.,Shanghai Urban Planning and Design Research Institute |
Chen X.,Tongji University |
Dong J.,University of Shanghai for Science and Technology
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2014
In accordance with the layout of Shanghai international shipping center and based on the optimization model for the freight collection and distribution system of ports with minimized generalized cost, this paper established a generalized cost function for road sections of various transportation forms including highway, waterway and railway as well as for transfer hubs. Major parameters were defined, the freight analyzing software STAN was used to realize the balanced distribution of the overall network and data concerning the handling capacity and distribution of major hub ports was thus obtained. The result showed that Shanghai international shipping center is developing into a multi-center port, that the overall service capacity for major hub ports has been enhanced and that though the proportion of waterway freight transportation is on the rise, the highway freight collection and distribution system still needs to expand its transportation scale.