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Ren Y.,Chinese Institute of Urban Environment | Wei X.,Chinese Institute of Urban Environment | Wei X.,University of British Columbia | Pan J.,Fujian Forestry Investigating and Planning Institute | And 4 more authors.
Forest Ecology and Management | Year: 2011

Rapid growth of the Chinese urban population and the expansion of urban areas have led to changes in urban forest structure and composition, and consequently changes in vegetation carbon storage. The purpose of this study is to quantify the effects of urbanization on vegetation carbon storage in Xiamen, a city located in southern China. Data used for this study were collected from 39,723 sample plots managed according to the forest management planning inventory program. Data from these plots were collected in 4 non-consecutive years: 1972, 1988, 1996 and 2006. The study area was divided into three zones, which were defined according to their level of urbanization: the urban core, the suburban zone, and the exurban zone. Total vegetation carbon storage and the vegetation carbon density for each study period were calculated for each zone. Our results show that urban vegetation carbon storage has increased by 865,589.71. t during the period from 1972 to 2006 (34 years) in Xiamen, with a rapid increase between 1972 and 1996, then relatively little change between 1996 and 2006. The increase in vegetation carbon storage is mainly due to the large percentages of the suburban and exurban areas which exist in Xiamen city, and the implementation of reforestation programs in these two zones. The percentage of total regional carbon storage in the city center (urban core), suburbs and exurbs was 5%, 23% and 72%, respectively. This demonstrates that the exurbs store the majority of vegetation carbon, and thus play a critical role in the vegetation carbon storage of the study area. The intensification of urbanization in the future will likely expand the urban core and reduce the area of the suburbs and exurbs, and thus potentially decrease total vegetation carbon storage. This article concludes with a discussion of the implications of these results for vegetation carbon management and urban landscape planning. © 2011 Elsevier B.V.


Chen B.,Liming Vocational University | Chen B.,Fujian University of Technology
Journal Wuhan University of Technology, Materials Science Edition | Year: 2015

A self-made 2-acrylamide-2-methyl propylene sulfonic (AMPS)-modified polyacrylic acid superplasticizer and two other commercially available superplasticizers with different molecular structures are used in this study to investigate the effect of an AMPS-modified polyacrylic acid superplasticizer on the properties of concrete materials. In the experiments, initial and 1.5 h slumps over time after admixtion are determined by adding different dosages of three superplasticizers into the premixed concrete to characterize the slump loss resistance of the premixed concrete. The water-reducing rates of three different types of concrete are determined to characterize the water-reducing capacity of the concrete with each superplasticizer. The 3, 7 and 28 d compressive strength is determined to characterize the mechanical properties of the concrete with each superplasticizer. In the meanwhile, 1, 1.5 and 2.0 h slump loss rates over time after admixtion are determined by adding different dosages of the three superplasticizers into the high-performance concrete (HPC) to characterize the slump loss resistance of HPC. The 7, 28, 60 and 90 d compressive strength is determined to characterize the compressive properties of HPC with each superplasticizer. The dry shrinkage rates of three different types of HPC are determined with each superplasticizer. Electric flux after standard curing for 56 d and chloride ion diffusion coefficient after curing for 28 d of HPC are determined to characterize the impermeability of HPC with each superplasticizer. The cross-section was examined using a scanning electron microscopy (SEM) system. Results demonstrate that the AMPS-modified polyacrylic acid superplasticizer has better water-reducing effect and slump than the two commercially available polyacrylic acid superplasticizers. The AMPS-modified polyacrylic acid superplasticizer also shows significant improvement of the compressive strength, especially in comprehensive performance of HPC. In conclusion, the AMPS-modified polyacrylic acid superplasticizer is particularly suitable for the preparation of HPC. © 2015, Wuhan University of Technology and Springer-Verlag Berlin Heidelberg.


Chen B.,Liming Vocational University | Chen B.,Fujian University of Technology
Journal Wuhan University of Technology, Materials Science Edition | Year: 2015

A self-made AMPS-modified polyacrylic acid superplasticizer and two others of the same type but with different molecular structures, which are commercially available, are used in this study to investigate the effect of a 2-acrylamide-2-methyl propylene sulfonic (AMPS)-modified polyacrylic acid superplasticizer on the properties of cement-based materials. In the experiments, initial fluidity, 1 and 2 h fluidity over time after admixtion, bleeding rate of the net cement mortar, and adsorption capacity and rate of cement particles are determined by adding different dosages of the three superplasticizers into the cement paste to characterize the dispersivity and the dispersion retention capability of each superplasticizer. Water-reducing rates of three kinds of mortars are simultaneously determined to characterize the water-reducing capacity of each superplasticizer, as well as the 3 and 28 d compressive strengths to characterize the compression resistance. Results show that water-reducing effect and fluidity better maintain the capability of the AMPS-modified polyacrylic acid superplasticizer than the two commercially available polyacrylic acid superplasticizers, and the compressive strengths after 3 and 28 d show significant growth. In conclusion, the effects of water reduction and strengthening of the AMPS-modified polyacrylic acid superplasticizer are evidently better than those of the two commercially available polyacrylic acid superplasticizers. © 2015, Wuhan University of Technology and Springer-Verlag Berlin Heidelberg.


Chen B.,Liming Vocational University | Chen B.,Fujian University of Technology
Journal Wuhan University of Technology, Materials Science Edition | Year: 2013

A 2-acrylamide-2-methyl propylene sodium sulfonic (AMPS)-modified polyacrylic acid superplasticizer was synthesized using aqueous solution polymerization with the major monomers including the self-made active macromers polyethylene glycol mono-methyl ether acrylate acrylic (MPEGAA), acrylic acid (AA), AMPS, and sodium methyl allyl sulfonate (SMAS). The ratios of the monomers were determined using an orthogonal experiment. This research focused on the effects of the dosages of different macromers, the polymerization conditions, and the length of MPEGAA side chains on the properties of the AMPS-modified polyacrylic acid superplasticizer. The best polymerization conditions of the AMPS-modified polyacrylic acid superplasticizer are when (n(MPEGAA):n(SMAS): n(AMPS):n(AA) equals 0.1:0.1:0.2:0.65, the molecular weight of monomethoxypolyethylene glycol is 1 200, the initiator ammonium persulfate accounts for 5% of the total mass of the polymerized monomers, the polymerization temperature is 80 C, and the reaction time is 4 h. The AMPS-modified polyacrylic acid superplasticizer synthesized in the best conditions exhibited excellent dispersivity and dispersion retainability. When the dosage ratio was 0.24%, the initial fluidity was 400 mm and the fluidity had nearly no loss after 1 h. © 2013 Wuhan University of Technology and Springer-Verlag Berlin Heidelberg.


Chen B.,Liming Vocational University | Chen B.,Fujian University of Technology
Journal Wuhan University of Technology, Materials Science Edition | Year: 2013

A macromer, methoxypolyethylene glycol acrylate (MPEGAA), was synthesized by direct esterification using methoxypolyethylene glycol (MPEG-1200) and acrylic acid (AA) as the main materials. MPEGAA was then used to prepare a polyacrylic acid superplasticizer modified with 2-acrylamido-2-methylpropane sulfonic acid (AMPS). A single-factor test was performed to investigate the effects of the molar ratio of acid to alcohol (n(AA)/n(MPEG)), inhibitor amount, catalyst amount, temperature, and time of esterification on the synthesis of MPEGAA. The experimental results showed that the optimal esterification conditions were as follows: n(AA)/n(MPEG), 3.5:1; amount of hydroquinone (as an inhibitor), 1.2%; amount of para-toluenesulfonic acid (as a catalyst), 5.5%; reaction temperature, 95 C; and reaction time, 6 h. The AMPS-modified polyacrylic acid superplasticizer prepared under the optimal esterification conditions enabled the achievement and maintenance of high cement dispersibility. At an admixture amount of 0.15%, the cement paste fluidity was initially as high as 300 mm, and then decreased to 315 mm after 1 h and to 290 mm after 2 h. © 2013 Wuhan University of Technology and Springer-Verlag Berlin Heidelberg.


Chen B.,Liming Vocational University | Chen B.,Fujian University of Technology
Journal Wuhan University of Technology, Materials Science Edition | Year: 2013

The regeneration aggregate, natural aggregate, P·O42.5 R Portland cement, coal fly ash, and slag powders S95 graining blast furnace, homemade P(AA-co-MA)/PEG carboxylic acid water reducing agent, were used together with recycled concrete aggregate in different regeneration rates to prepare recycled concrete (RC). The influences of different renewable aggregate ratios on the basic RC replacement mechanical properties, uniaxial compression stress and strain curve, and the elastic modulus and rebound value were investigated.The results show that RC mechanical properties decreases with renewable aggregate replacement rate increasing. The prolongation can reduce the reduced span. © 2013 Wuhan University of Technology and Springer-Verlag Berlin Heidelberg.


Li Y.-L.,Liming Vocational University | Ke A.-R.,Liming Vocational University | Lin S.-B.,Liming Vocational University | Ouyang N.,Liming Vocational University
International Journal of Polymeric Materials and Polymeric Biomaterials | Year: 2011

Polyacrylamide and poly(2-acrylamido-2-methyl propyl sulfonic acid) co-polymer[short as P(AM-co-AMPS)] superabsorbent materials were synthesized using 2-acrylamido-2-methyl propyl sulfonic acid and acrylamide as monomers, and P(AM-co-AMPS)/SiO2 hybrid superabsorbent materials were prepared using P(AM-co-AMPS) as the organic phase and SiO2 as the inorganic phase. The absorbent properties of these two kinds of superabsorbent materials were investigated. Fourier-transform infrared (FT-IR) and scanning electron microscopes (SEM) were used to characterize these two kinds of superabsorbent materials. The result shows that the SiO2 can disperse in P(AM-co-AMPS) polymer networks homogeneously. The water-absorbent ability of P(AM-co-AMPS)/SiO2 and P(AM-co-AMPS) is similar, but P(AM-co-AMPS)/SiO2 exhibits better acid, base, salt, organic solvents, and temperature tolerance than the P(AM-co-AMPS) dose. In addition, the swelling speed of P(AM-co-AMPS)/SiO2 is larger than that of P(AM-co-AMPS). Copyright © Taylor & Francis Group, LLC.


Xu L.,Liming Vocational University
MATEC Web of Conferences | Year: 2016

A connectionist investigation of irreversible Stirling heat pump cycles that includes both internal and external irreversibilities together finite heat capacities of external reservoirs was carried out. The thermoeconomic optimization for Stirling heat pump is reported. The heating load per unit total cost for the heat pump is proposed as objective functions for the optimization. The optimum performance parameters which maximize the objective functions are investigated. Since the optimization technique consists of both investment and energy consumption costs, the obtained results are more general and realistic. © 2016 The Authors, published by EDP Sciences.


Zeng R.,Liming Vocational University | Zeng H.,Hewlett - Packard
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Although anaglyphs have a big advantage that they can be presented using traditional single channel media such as print, film, display, etc., a media type must be determined as a pair of views is combined into a single image to minimize retinal rivalry and stereo crosstalk. Most of anaglyph maps and map tools are optimized for display and assumed using red-cyan filtered glasses for viewing. Due to the large difference between a display gamut and a printer gamut, red and cyan colors that are used to separate the left view and the right view are changed considerably as they are mapped from a display color space to a printer color space for printing and results in serious retinal rivalry. A solution using a special gamut mapping method to preserve the relative relationship of cyanish and reddish colors was developed to gamut map colors from display to printer. And the color characterization to balance neutral colors for specific red/cyan glasses is applied to further improve the color appearance. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Chen B.,Liming Vocational University
Applied Mechanics and Materials | Year: 2013

This paper sets forth from the effect analysis of the concrete raw materials and all kinds of the performance index tests. It makes further research and exploration of the mix proportion design of P (AA-co-MA)/PEG polycarboxylic copolymer and high performance concrete with composite admixture, combining the mixture of the high performance concrete as well as the performances such as the workability, the hardness of the cement setting and hardening and the endurance quality. It is found that mixing 1.46% P (AA-co-MA)/PEG polycarboxylic copolymer, 15% fly ash and 10% granulated blast furnace slag powder together and adding the mixture into the concrete can not only save the cement but also improve the performance of the concrete. The designed C30 mix proportion design of P (AA-co-MA)/PEG polycarboxylic copolymer and high performance concrete with composite admixture has been applied successfully in the high-rise building construction. © (2013) Trans Tech Publications, Switzerland.

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