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Zhao C.,China Urban Construction Design and Research Institute | Fu G.,CAS Institute of Geographical Sciences and Natural Resources Research | Fu G.,CSIRO | Liu X.,Beijing Forestry University | Fu F.,North China University of Technology
Building and Environment | Year: 2011

Eleven sites, representing different urban morphologies across central Beijing, are used to simulate urban heat island effects and explore the relationship between urban planning indicators and climate indicators such as daily maximum and minimum surface temperatures. The results indicate that mesoscale urban planning indicators can explain the majority of the urban climate differences among the sites. For example, green cover ratio and floor area ratio can explain 94.47-98.57% of the variance for daily maximum surface temperature, green cover ratio and building height can explain 98.94-99.12% of the variance for daily minimum surface temperature, and floor area ratio, green cover ratio and building density together can explain 99.49-99.69% of the variance for time of peak surface temperature. Furthermore, green cover ratio is identified as the most significant urban planning indicator affecting the urban thermal environment. © 2010 Elsevier Ltd. Source


Gao X.,Chinese Research Academy of Environmental Sciences | Liu X.,China Urban Construction Design and Research Institute | Wang W.,Tsinghua University
Renewable Energy | Year: 2016

Biodegradation of particulate organics is considered to be as an essential factor in the anaerobic co-digestion performance and biogas recovery of biowaste. To determine the rate-limiting step of particulate organics hydrolysis during co-digestion of municipal biowaste and waste activated sludge (WAS), the particle size distribution of organic compounds before and after digestion was examined for a mesophilic co-digestion system. As organic load rate increased and hydraulic retention time decreased, the removal rate of big-size particulate organics did not change significantly, indicating that the disintegration of big particles is not the rate-limiting step, while soluble organics accumulated in the digestate. This implies that the enzymatic hydrolysis of soluble organics is the rate-limiting step in the hydrolysis process. Addition of WAS to substrate did not significantly change the removal rate of particulate organics >420 μm, while the residual content of particulate organics 0.45-74 μm in size increased because the non-biodegradable organics in WAS were in this size range. After biodegradability enhancement of WAS by hydrothermal pretreatment, the removal rate of particulate organics increased significantly. Thus, biodegradability enhancement is more effective than particle size reduction in optimizing the co-digestion process with WAS in practice. © 2016 Elsevier Ltd. All rights reserved. Source


Sun W.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Sun W.,Chinese Academy of Sciences | Han X.,China Urban Construction Design and Research Institute | Sheng K.,Shandong University of Technology | And 2 more authors.
Journal of Mountain Science | Year: 2012

China is a mountainous country, and Southwest mountain areas cover the most mountain areas in China and have the most serious problems. Taking Zhaotong city as the study area, based on 902 rural household questionnaires of 11 villages in 2 counties and Tobit model, this paper analyzes the geographical differences and influencing factors of energy consumption for non-production purposes of rural households living in different terrain conditions. This research finds that: (1) Coal takes up the main part of energy consumption in valley areas and coal consumption is mainly affected by per capita cultivated land area, household income, proportion of rural household energy expenditure in total expenditure, coal price, and family population size. Firewood takes up the main part of energy consumption in high mountain areas and firewood consumption is mainly affected by per capita firewood forest area, distance to purchase coal, household income, electricity price, and coal price. (2) Only when the distance is greater than 20 kilometers, that is the average distance of rural households living in middle mountain areas (1,600m~1,800m) to purchase coal, the transportation condition has a significant impact on coal consumption. (3) In high mountain areas, prices of coal and electricity are the main factors influencing energy consumption choice of rural households. Too high prices of coal and electricity would to some extent lead rural households to choose firewood as the main energy consumption type. Compared to coal, rural households prefer to choose electricity. © 2012 Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg. Source


Liu P.,Beijing Jiaotong University | Guo M.,Beijing Jiaotong University | Guo M.,China Academy of Building Research | Li T.,Beijing Jiaotong University | And 2 more authors.
Gongcheng Lixue/Engineering Mechanics | Year: 2012

Similar to the multi-grid composite wall reinforced by steel bars, an improved multi-grid composite wall reinforced by light steels is proposed, where the steel bars in grid beams and columns are replaced by light steels. To apply the improved composite in large-bay high-rise buildings, its seismic performance should be examined. 1/2 scale multi-grid composite walls reinforced by light steels, as well as by steel bars, were tested under reversed cyclic loading. Damage procedures, load-bearing capacity and ductility were compared. It is found that both kinds of walls fail in shear, and the damage propagates from the filling blocks to grids made up of grid beams and columns, and finally to the edged frame. Compared with using steel bars, using light steels to reinforce composite walls, with a 17% increase of steel, generated a yielding capacity of 54.3% larger and an ultimate capacity of 53.1% larger. The stiffness behavior and energy dissipation capacity of the improved composite wall were better too, while the ductility capacity of the two composite walls was almost the same. Source


Chen T.,Tsinghua University | Jin Y.,Tsinghua University | Qiu X.,China Urban Construction Design and Research Institute | Chen X.,Tsinghua University
Expert Systems with Applications | Year: 2014

The product safety of food-waste feed is the key factor limiting the development of its industrial chain. In this paper, we construct a method based on data from the testing of food-waste feed with comprehensive evaluation of its product safety by integrating fuzzy mathematics effectively, i.e.; the entropy method (EM), and the model of the analytic hierarchy (AHP) process. Furthermore, a hierarchical three-level evaluation-index system including biological-safety and chemical-safety considerations is first established via data analysis, data surveys and expert experiential investigation as well, with an actual case in China being fully applied. In addition, we apply the EM and AHP process to calculate the weights of the individual evaluation indices. Finally, through the dimensionless treatment of test data from samples, we determine the degree of membership of each test value relative to the different levels of safety using a trapezoidal membership function. By adopting the developed three-level model of fuzzy mathematics for comprehensive evaluation, we derive the safety grades of tested samples. The comprehensive evaluation method developed in this paper can effectively overcome the shortcomings of traditional single-factor evaluation and offer the qualitative and quantitative advantages of expert survey and basic data research as well. As a result, it is considerably applicable for the product-safety analysis and production control of animal feed generated from food waste. © 2014 Elsevier Ltd. All rights reserved. Source

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