Han F.,China University of Mining and Technology |
Zhang Y.,Tianjin Academy of Environmental science
Journal of Computational and Theoretical Nanoscience | Year: 2016
Environmental carrying capacity of Chinese cities is of great significance in the social prediction and social management. The change regulation of the environmental carrying capacity in Chinese cities is various from year to year. Previous research use the multiple linear regression (MLR) method to develop a series of prediction models for the prediction of environmental carrying capacity. However, results are not accurate enough. It is highly difficult to measure the impacts of different independent variables because of the randomness of social science. Therefore, the MLR approach may not quite suitable for adapting the actual applications. Here, we present two strong models in order to improve the prediction precision of the environmental carrying capacity of Chinese cities. Artificial neural networks (ANNs) and grey model GM (1, 1) prediction is proposed. We use general regression neural network (GRNN) and multi-layer feed-forward neural network (MLFN) models as the trained ANN models. Best net search approach is used for searching the most suitable ANN model according to the RMSE and training time. GM (1, 1) model is proposed using the number sequence of the year, which is dependent to various independent variables. Results show that both the ANNs and GM (1, 1) can be effectively used for the prediction of the environmental carrying capacity of Chinese cities. Under different conditions can we decide to use a certain suitable prediction model. Copyright © 2016 American Scientific Publishers All rights reserved.
Liu S.,Tianjin University of Technology |
Wang X.,Tianjin University of Technology |
Zhao W.,Tianjin Academy of Environmental science |
Wang K.,Tianjin University of Technology |
And 2 more authors.
Journal of Alloys and Compounds | Year: 2013
A series of composite photocatalysts comprised of ZnO nanorods core and ZnS-Ag2S heterostructural shell layer with different Ag 2S/ZnS molar ratios have been synthesized via the combination of a low-temperature hydrothermal growth and cation exchange technique. The core/shell nanorods, with the diameters of about 150 nm and the lengths of ranging from a few 100 nm to several micrometers, were fabricated by coating the ZnO nanorods with a layer of ZnS and Ag2S composite shell mainly consisting of nanocrystals with the diameters of about 5-8 nm. The characterization from SEM, TEM, EDX, XPS, and UV-Vis DRS reveals that the molar ratio of Ag2S/ZnS in shell layer strongly affects the morphologies, distribution of components, photo absorption, and photocatalytic performance of the ZnO/ZnS-Ag2S core/shell nanorods. Due to the coupling with low bandgap material Ag2S, the ZnO/ZnS-Ag2S nanorods have a much higher solar-simulated light absorption capability than that of ZnO/ZnS. As a result, the as-prepared ZnO/ZnS-Ag2S nanocomposites exhibited much higher catalytic efficiency for the hydrogen production from glycerol aqueous solution. The superior photo absorption properties and photocatalytic performance of the ZnO/ZnS-Ag2S core/shell nanorods may be ascribed to the heterostructure, which enhanced the separation of photo-induced electron-hole pairs. © 2013 Elsevier B.V. All rights reserved.
Yang Y.,Tianjin Academy of Environmental science |
Chen Y.,Tianjin Academy of Environmental science |
Zhang X.,Beijing Normal University |
Ongley E.,Beijing Normal University |
And 2 more authors.
Environmental Pollution | Year: 2012
Agricultural non-point source (NPS) pollution has been recently identified by the Chinese government as a major source of aquatic pollution. Methodologies commonly used to make basin-wide or area-wide assessments are problematic and regional distinctions have not been made relative to rainfall and runoff. Using a typical agricultural county in the Hai River basin of the North China Plan we developed methodology to estimate potential load and delivered load for crops (field crops + rice), animal production, rural living and from atmospheric N input. We use scenarios to allow for uncertainty in delivery to estimate the relative roles of different rural forms of pollution. Livestock raising is the major source of NPS pollution. Despite a 75% rural population, rural living contributes almost nothing to surface water pollution. While over-fertilization is typical, nutrient runoff from crops is low. Our results have implications for policies now under development for NPS control in China. © 2012 Elsevier Ltd. All rights reserved.
Zhao W.,Tianjin Academy of Environmental science |
Wang X.,Tianjin University of Technology |
Sang H.,Tianjin Academy of Environmental science |
Wang K.,Tianjin University of Technology
Chinese Journal of Chemistry | Year: 2013
Bi-doped TiO2 nanotubes with variable Bi/Ti ratios were synthesized by hydrothermal treatment in 10 mol·L-1 NaOH (aq.) through using Bi-doped TiO2 particles derived from conventional sol-gel method as starting materials. The effects of Bi content on the morphology, textural properties, photo absorption and photocatalytic activity of TiO2 nanotubes were investigated. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) observations of the obtained samples revealed the formation of titanate nanotube structure doped with Bi, which exists as a higher oxidation state than Bi3+. Bi-doping TiO2 nanotubes exhibited an extension of light absorption into the visible region and improved photocatalytic activities for hydrogen production from a glycerol/water mixed solution as compared with pure TiO2 nanotubes. There was an optimal Bi-doped content for the photocatalytic hydrogen production, and high content of Bi would retard the phase transition of titanate to anatase and result in morphology change from nanotube to nanobelt, which in turn decreases the photocatlytic activity for hydrogen evolution. Copyright © 2013 SIOC, CAS, Shanghai & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Su W.,The Third Railway Survey and Design Institute Group Corporation |
Pan X.,The Third Railway Survey and Design Institute Group Corporation |
Ye P.,Tianjin Academy of Environmental science
Zhongguo Tiedao Kexue/China Railway Science | Year: 2013
Based on multi-channel aligned array sound source identification system and multi-channel noise vibration real-time acquisition analysis system, the noise source, the distribution of spatial sound field and the reduction effect of noise barrier were tested and analyzed under train operation state for Beijing-Tianjin intercity and Jing-Hu high-speed railway. The sound source of high-speed train is equivalent to lower part noise and upper part noise. The noise of lower part mainly includes wheel rail noise and the aerodynamic noise of car body, and its sound source is equivalent to 0.6 m above rail surface. The noise of upper part is mainly pantograph-catenary noise, and its sound source is equivalent to 3.3 m above rail surface. Therefore, the acoustic computing model for the noise barrier of high-speed railway is proposed, which is based on dual sound source as the equivalent sound source and 1250 Hz as the equivalent frequency. The correction and calculation formula for the insertion loss and extension part of noise barrier is given. The obtained acoustic computing result of sound barrier agrees well with the measured result.
Yu H.,Tianjin Research Institute for Water Transport Engineering |
Tao L.,Tianjin Academy of Environmental science
Advanced Materials Research | Year: 2011
A novel method with two steps for preparing high efficiency fluorescence nanocrystals (NCs)-encoded microspheres was developed. First, a series of polystyrene (PS) microspheres from 1 μm to 5 μm in diameter were prepared by dispersion polymerization; then, after a swelling process with CdSe NCs of different size the PS microspheres were encoded quantitatively. This method for fluorescence-encoding of microspheres was shown to have the following outstanding characteristics: (1) An emulsion containing CdSe NCs and swelling agents (chloroform) are firstly used for introduction of NCs into microspheres. (2) The embedded nanocrystals remain their original properties and they are not simply absorbed onto the surface of the microspheres but being carried into the inner of microspheres and so the NCs cannot be released or leaked out easily. As-prepared fluorescence-encoded microspheres could conjugate with proteins by some further surface modification, so they have a great potential to be applied to such fields as biochemistry, molecular biology, cell biology, immunology, etc. In addition, the method could be operated easily and reproducibly. © (2011) Trans Tech Publications, Switzerland.
Li W.,Nankai University |
Li W.,Tianjin Academy of Environmental Science |
Peng Y.,Liaoning Provincial Environmental Monitoring Center |
Shi J.,Nankai University |
And 3 more authors.
Atmospheric Environment | Year: 2011
In this study, concentrations of polycyclic aromatic hydrocarbons (PAHs) associated with PM 10 were measured to examine the status, characteristics and sources of atmospheric PAH pollution in the industrial Northeast Region of China. Mean concentrations of total PAHs were 65.5, 40.0, 73.0 and 436.7 ng m -3 in the four seasons respectively. The calculated BaPeq concentrations in winter all exceeded the national standard, imposing serious PAH exposure risk. PAH concentrations varied between the cities, but PAH concentrations in different functional areas within a city did not show significant difference. In general, particulate PAH profiles were dominated by 4- and 5-ring compounds. Elevated proportions of 3-ring PAHs and 5-ring PAHs were found in winter and in summer respectively. Diagnostic ratios and principal component analysis (PCA) were used to identify potential sources of PAHs. Coal combustion activities were the main contributors of particle-associated PAHs in this region. © 2011 Elsevier Ltd. All rights reserved.
Jianli M.,Tongji University |
Jianli M.,Tianjin Academy of Environmental Science |
Youcai Z.,Tongji University |
Jinmei W.,Tianjin Academy of Environmental Science |
Li W.,Tongji University
Construction and Building Materials | Year: 2010
Solidification/stabilization (S/S) is considered to be a well-established disposal technique to reduce sludge handling and disposal obstacles. In this work, the sewage sludge was solidified at variable proportions with magnesium oxychloride cement (denoted as MOC thereinafter) as reagent. The mortar prism samples of 40 × 40 × 160 mm in dimension were prepared and hardened for 24 h at room temperature. Unconfined compressive strength after 10-day curing time, initial and final setting time, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and toxicity leachability of the samples, were used to characterize the macroscopic and microscopic effects caused by the solidified products on the MOC hydration process. The results revealed that the magnesium hydration of phase 3, phase 5 and other hydration components in CS developed a crystallizing network in the hydrated solidified products, which not only enhanced the strength of CS but also prevented the precipitation of heavy metal ions from CS. © 2009 Elsevier Ltd. All rights reserved.
Tang J.,Nankai University |
Lu X.,Tianjin Academy of Environmental science |
Sun Q.,Nankai University |
Zhu W.,Nankai University
Agriculture, Ecosystems and Environment | Year: 2012
In this paper, aging process of petroleum-contaminated soil was characterized during 210. d of attenuation under different conditions: clean soil spiked with petroleum (Run 1), clean soil spiked with petroleum and humic acid (Run 2), quartz sand spiked with petroleum (Run 3) and petroleum-contaminated saline soil from an oil field (Run 4). An initial increase of pH was found before 60. d of aging. Total petroleum hydrocarbon (TPH) content decreased with the process of aging and the degradation rates for the 4 runs were 61%, 60%, 24% and 20% after 210. d of aging, respectively. The saturated fraction of petroleum hydrocarbons was most degraded in Run 1 in clean soil; while addition of humic acid enhanced the degradation of aromatic fraction and asphaltene and polar fraction. Addition of TPH in soil resulted in the increase of the dehydrogenase activity at the initial period of aging. A significant negative correlation was found between bacteria count and TPH content during aging process and fungi number was only increased at certain time of aging. The biological toxicity increased at the middle of aging process of 30-60. d as determined by plant growth and luminescent bacteria experiment. The result suggested that proper regulation on the influencing factors such as particle size and salinity was important for the management of contaminated soils and could enhance the natural attenuation of the petroleum pollutants. © 2012 Elsevier B.V.
Gu Z.-Y.,Nankai University |
Wang G.,Tianjin Academy of Environmental science |
Yan X.-P.,Nankai University
Analytical Chemistry | Year: 2010
Metal-organic frameworks (MOFs) are one kind of highly porous crystalline materials, which are constructed by metal-containing inorganic nodes and organic linkers. With large surface area and high thermal stability, MOFs have great potential as sorbents for the preconcentration of trace analytes. However, such application of MOFs to the analysis of real samples has not been reported before. Here we report the utilization of MOF-5 as sorbent for in-field sampling and preconcentration of atmospheric formaldehyde before thermal desorption (TD) GC/MS (TD-GC/ MS) determination without the need for any chemical derivatization. MOF-5 gave a 53 and 73 times better concentration effect than Tenax TA (organic polymers) and Carbograph 1TD (graphitized carbon black), respectively, for TD-GC/MS determination of formaldehyde. MOF-5 showed good performance for in-field sampling and preconcentration of formaldehyde from air samples with a relative humidity less than 45%. The collected formaldehyde on MOF-5 sorbent was stable for at least 72 h at room temperature before TD-GC/MS analysis. One tube packed with 300 mg of MOF-5 lasted 200 cycles of adsorption/TD without significant loss of collection ef-ficiency. The breakthrough volume of such a tube was 1.2 L of 28.35 mg m-3 formaldehyde at a sampling flow rate of 100 mL min-1. The use of MOF-5 for in-field sampling and preconcentration in combination with TD-GC/MS for the determination of formaldehyde offered a linear range covering 3 orders of magnitude, and a detection limit of 0.6 μ g m-3. The precision for six replicate cycles of in-field sampling and preconcentration for TD-GC/MS determination using one 300 mg MOF-5 packed tube ranged from 2.8% to 5.3%. The tube-to-tube reproducibility of three MOF-5 tubes prepared in parallel was 7.7%. The developed method was applied to analysis of local indoor and outdoor air samples for formaldehyde and validated by the standard method TO-11A of the United States Environmental Protection Agency. The concentration of formaldehyde and the recovery of spiked formaldehyde in the air samples ranged from 12 to 48 μ gm-3, and from 93% to 107%, respectively. © 2010 American Chemical Society.