The sulfate-methane interface is an important biogeochemical identification interface for the areas with high methane flux and containing gas hydrate. Above the sulfate-methane interface, the sulfate concentration in ...The sulfate-methane interface is an important biogeochemical identification interface for the areas with high methane flux and containing gas hydrate. Above the sulfate-methane interface, the sulfate concentration in the sediment is consumed progressively for the decomposition of the organic matter and anaerobic methane oxidation. Below the sulfate-methane interface, the methane concentration increases continuously with the depth. Based on the variation characters of the sulfate and methane concentration around the sulfate-methane interface, it is feasible to estimate the intensity of the methane flux, and thereafter to infer the possible occurrence of gas hydrate. The geochemical data of the pore water taken from the northern slope of the South China Sea show the sulfate-methane interface is relatively shallow, which indicates that this area has the high methane flux. It is considered that the high methane flux is most probably caused by the occurrence of underlying gas hydrate in the northern slope of the South China Sea.展开更多
The refractive indices of disordered (Al xGa 1-x ) 0 51 In 0 49 P,which is grown by low-pressure organometallic vapor phase epitaxy and lattice-matched to GaAs substrate,have been determined by measurin...The refractive indices of disordered (Al xGa 1-x ) 0 51 In 0 49 P,which is grown by low-pressure organometallic vapor phase epitaxy and lattice-matched to GaAs substrate,have been determined by measuring their reflectance spectra when the wavelength ranges between 0 5 to 2 5 micrometer.A single-oscillator dispersion model is used to verify the experiment data and calculate the reflectance spectrum.The refractive indices are used to analyze the waveguide of strain quantum well GaInP/AlGaInP visible laser diode.The simulated far field pattern is consistent with the experimental results very well.展开更多
The hygroscopic properties of mixed aerosol particles are crucial for the application of remote sensing products of aerosol optical parameters in the study of air quality and climate at multiple scales. In this study,...The hygroscopic properties of mixed aerosol particles are crucial for the application of remote sensing products of aerosol optical parameters in the study of air quality and climate at multiple scales. In this study, the authors investigated aerosol optical properties as a func tion of relative humidity （RH） for two representative me tropolises： Beijing and Hong Kong. In addition to the RH data, mass concentrations of PM10 （particulate matter up to 10 utm in diameter） and aerosol scattering extinction coefficient （aext） data were used. The relationship between the mass scattering extinction efficiency （MEE, defined as O＇ext/PMl0） and RH can be expressed by regression func tions asf= 1.52x ＋ 0.29 （re= 0.77）,f= 1.42x ＋ 1.53 （re= 0.58）,f= 1.19x ＋ 0.65 （re= 0.59）, andf= 1.58x ＋ 1.30 （re = 0.61） for spring, summer, autumn, and winter, respec tively, in Beijing. Here, f represents MEE, x represents I/（1-RH）, and the coefficients of determination are pre sented in parentheses. Conversely, in Hong Kong, the corresponding functions are f= 1.98x- 1.40 （r^2= 0.55）,f = 1.32x - 0.36 （r^2 = 0.26）,f= 1.87x - 0.65 （r^2 = 0.64）, and f= 2.39x - 1.47 （r^2 = 0.72）, respectively. The MEE values for Hong Kong at high RHs （RH 〉 70%） are higher than those for Beijing, except in summer; this suggests that aerosols in Hong Kong are more hygroscopic than those in Beijing for the other three seasons, but the aerosol hy groscopicity is similarly high in summer over both cities. This study describes the effects of moisture on aerosol scattering extinction coefficients and provides a potential method of studying atmospheric visibility and ground level air quality using some of the optical remote sensing products of satellites.展开更多
Gas outbursts in underground mining occur under conditions of high gas desorption rate and gas content,combined with high stress regime, low coal strength and high Young's modulus. This combination of gas and stre...Gas outbursts in underground mining occur under conditions of high gas desorption rate and gas content,combined with high stress regime, low coal strength and high Young's modulus. This combination of gas and stress factors occurs more often in deep mining. Hence, as the depth of mining increases, the potential for outburst increases. This study proposes a conceptual model to evaluate outburst potential in terms of an outburst indicator. The model was used to evaluate the potential for gas outburst in two mines, by comparing numerical simulations of gas flow behavior under typical stress regimes in an Australian gassy mine extracting a medium-volatile bituminous coal, and a Chinese gassy coal mine in Qinshui Basin(Shanxi province) extracting anthracite coal. We coupled the stress simulation program(FLAC3D) with the gas simulation program(SIMED II) to compute the stress and gas pressure and gas content distribution following development of a roadway into the targeted coal seams. The data from gas content and stress distribution were then used to quantify the intensity of energy release in the event of an outburst.展开更多
The knowledge of flow regime is very important for quantifying the pressure drop, the stability and safety of two-phase flow systems. Based on image multi-feature fusion and support vector machine, a new method to ide...The knowledge of flow regime is very important for quantifying the pressure drop, the stability and safety of two-phase flow systems. Based on image multi-feature fusion and support vector machine, a new method to identify flow regime in two-phase flow was presented. Firstly, gas-liquid two-phase flow images including bub- bly flow, plug flow, slug flow, stratified flow, wavy flow, annular flow and mist flow were captured by digital high speed video systems in the horizontal tube. The image moment invariants and gray level co-occurrence matrix texture features were extracted using image processing techniques. To improve the performance of a multiple classifier system, the rough sets theory was used for reducing the inessential factors. Furthermore, the support vector machine was trained by using these eigenvectors to reduce the dimension as flow regime samples, and the flow regime intelligent identification was realized. The test results showed that image features which were reduced with the rough sets theory could excellently reflect the difference between seven typical flow regimes, and successful training the support vector machine could quickly and accurately identify seven typical flow regimes of gas-liquid two-phase flow in the horizontal tube. Image multi-feature fusion method provided a new way to identify the gas-liquid two-phase flow, and achieved higher identification ability than that of single characteristic. The overall identification accuracy was 100%, and an estimate of the image processing time was 8 ms for online flow regime identification.展开更多
Promoter MgO on 10% CeO2/Al2O3 oxygen carrier was investigated for direct partial oxidation of methane to syngas in molten salt. The MgO content of 0.5%, 1%, 2%, 3% and 4% on the 10%CeO2/Al2O3 oxygen carriers in exper...Promoter MgO on 10% CeO2/Al2O3 oxygen carrier was investigated for direct partial oxidation of methane to syngas in molten salt. The MgO content of 0.5%, 1%, 2%, 3% and 4% on the 10%CeO2/Al2O3 oxygen carriers in experiments were prepared at the temperature of 750℃, respectively. The methane conversion, H2 and CO selectivity was measured on these prepared oxygen carriers at different reaction temperature. The results showed that the 3% MgO on 10%CeO2/Al2O3 had the best activity, and the CH4 conversion and CO selectivity reached 92.58% and 87.64% at 875℃, respectively. The effect of different calcination temperature on 3% MgO as promoter on 10% CeO2/Al2O3 oxygen carrier was investigated. The results of BET indicated that oxygen carrier had the largest surface area at 750℃. When the calcined temperature was too high there would be a negative effect on oxygen carrier activity.展开更多
In this work, Zr-M(M=Cu, Mn, Ce) type sulfur transfer agent was prepared by impregnation method. Under the condition similar to that in the regenerator of FCC units, the influence of different active metal components ...In this work, Zr-M(M=Cu, Mn, Ce) type sulfur transfer agent was prepared by impregnation method. Under the condition similar to that in the regenerator of FCC units, the influence of different active metal components and their contents on sulfur transfer agent were investigated. Moreover, the crystalline structure of sulfur transfer agent was characterized by X-ray diffraction(XRD) and Fourier transforms infrared spectroscopy(FT-IR). The result showed that the Zr-Mn sulfur transfer agent could effectively reduce the SO2 content in FCC regenerator flue gas, featuring high SO2 adsorption capacity. The sulfur transfer agent was inactivated in 40—60 min during the test. In the course of reduction reaction, after several reaction cycles, the formation of SO2 ceased and only H2 S was detected as the reduction product.展开更多
Glycerol pyrolysis is carried out in a fixed bed reactor filled with alumina oxide. The packing material diameter was examined according to each one, but in general it was varied between 0.1-5.0 mm. The reaction tempe...Glycerol pyrolysis is carried out in a fixed bed reactor filled with alumina oxide. The packing material diameter was examined according to each one, but in general it was varied between 0.1-5.0 mm. The reaction temperature was varied in the range of 700-900 ℃, the reaction time from 10 to 50 min and flow rate of carrier gas from 0 to 60 mL/min. The process parameters listed above （factors） were used to evaluate the syngas production yield （response）. Also, syngas properties such as composition and heat value were evaluated. The experiments were carried out according to a 23 factorial design plus three central points. At last, a technical-economical analysis is carried out to examine the feasibility of syngas production from glycerol pyrolysis considering not only feedstock, catalyst and energy required costs but also conventional procedures used nowadays to produce syngas such as water electrolysis and natural gas catalytic reform.展开更多
During the 15th Conference of the Parties （COP 15）, Parties agreed that reducing emissions from deforesta- tion and forest degradation and enhancing ＇removals of greenhouse gas emission by forests＇ （REDD＋） in d...During the 15th Conference of the Parties （COP 15）, Parties agreed that reducing emissions from deforesta- tion and forest degradation and enhancing ＇removals of greenhouse gas emission by forests＇ （REDD＋） in developing countries through positive incentives under the United Nations Framework Convention on Climate Change （UNFCCC） was capable of dealing with global emissions. As REDD＋ seeks to lower emissions by stopping deforestation and for- est degradation with an international payment tier according to baseline scenarios, opportunities for ecosystem benefits such as slowing habitat fragmentation, conservation of forest biodiversity, soil conservation may be also part of this effort. The primary objective of this study is to evaluate ecosystem-based benefits of REDD＋, and to identify the rela- tionships with carbon stock changes. To achieve this goal, high resolution satellite images are combined with Normal- ized Difference Vegetation Index （NDVI） to identify historical deforestation in study area of Central Kalimantan, In- donesia. The carbon emissions for the period of 2000-2005 and 2005-2009 are 2.73 ×10^5 t CO2 and 1.47× 10^6 t CO2 respectively, showing an increasing trend in recent years. Dring 2005-2009, number of patches （NP）, patch density （PD）, mean shape index distribution （SHAPE_MN） increased 30.8%, 30.7% and 7.6%. Meanwhile, largest patch index （LPI）, mean area （AREA MN）, area-weighted mean of shape index distribution （SHAPE_AM）, neighbor distance （ENN_MN） and interspersion and juxtaposition index （IJI） decreased by 55.3%, 29.7%, 15.8%, 53.4% and 21.5% re- spectively. The area regarding as positive correlation between carbon emissions and soil erosion was approximately 8.9 x l03 ha corresponding to 96.0% of the changing forest. These results support the view that there are strong syner- gies among carbon loss, forest fragmentation and soil erosion in tropical forests. Such mechanism of REDD＋ is likely to present opportunities for multiple benefits that fall outside the scope of carbon stocks.展开更多
The air quality directive （2008/50/EC （of the European Parliament and of the Council of 21 May 2008）） requires European Member States to design appropriate AQPs （air quality plans） for zones and agglomerations w...The air quality directive （2008/50/EC （of the European Parliament and of the Council of 21 May 2008）） requires European Member States to design appropriate AQPs （air quality plans） for zones and agglomerations where the air quality does not comply with the limit values and to assess possible emission reduction measures to decrease concentration levels. The Portuguese agglomeration of Porto Litoral is one of the several European Union urban areas that had to develop and implement AQPs to reduce particulate matter （PM10）. The AQPs were initially designed based on a scenario approach and using an air quality model, which was applied over the study region for the reference situation with the current PM10 emissions, and for a reduction scenario with PM10 emissions re-estimated considering the implementation of abatement measures. Aiming to cost-efficiently optimize Porto Litoral PM10 abatement measures, the assessment procedure was repeated using an optimization approach based on the RIAT ＋ （regional integrated assessment tool ＋）. Porto Litoral urban area＇s technical and non-technical measures were characterized （including associated costs） and, through the application of the air quality model to 20 emissions abatement scenarios, S-R （source-receptor） relationships were created. This paper comparatively describes the air quality plans designed to improve PM10 levels in the Porto Litoral agglomeration based on both the scenario analysis and the optimization approach.展开更多
The research works of methane concentration in water column of the Okhotsk Sea from 1984 to 2005 were reviewed.And some regularities of methane distribution in water column in the North-East Sakhalin slope of the Okho...The research works of methane concentration in water column of the Okhotsk Sea from 1984 to 2005 were reviewed.And some regularities of methane distribution in water column in the North-East Sakhalin slope of the Okhotsk Sea were concluded.展开更多
In this study, we selected 9 typical coal samples with different metamorphic grades as the study subjects,measured their initial 30-min gas desorption at 30℃ and different pressure using a self-developed gas adsorpti...In this study, we selected 9 typical coal samples with different metamorphic grades as the study subjects,measured their initial 30-min gas desorption at 30℃ and different pressure using a self-developed gas adsorption/desorption device. Based on the characteristics of gas desorption from coal samples, we proposed a direct fitting method for measurement of gas content in coalbed, analyzed the effects of sampling time on the measurement results and determined the reasonable sampling time of coal samples with different metamorphic grades at different gas adsorption pressure at equilibrium. The results show that (1)the error of gas contents obtained using the direct fitting method relative to that obtained using indirect method is less than 10%, which meets the actual on-site requirements and verifies the feasibility of the direct fitting method;(2) when the relative error is controlled within ±10%, the reasonable sampling time of coal samples is linearly related to the gas adsorption pressure at equilibrium;(3) the reasonable sampling time of coal samples with the same metamorphic grade exhibits a shortening trend with increasing gas adsorption pressure at equilibrium;(4) for coal samples with similar gas adsorption pressure at equilibrium, the reasonable sampling time of coal samples displays a shortening trend with increasing metamorphic grade. Overall, the study provides a basis for improving the measurement accuracy of gas content in coalbed.展开更多
In the Greater Casablanca, road transport is the second largest emissions source of gaseous pollutants and particles after the industry [ 1 ]. The emitters are mobile and include different categories of vehicles in ci...In the Greater Casablanca, road transport is the second largest emissions source of gaseous pollutants and particles after the industry [ 1 ]. The emitters are mobile and include different categories of vehicles in circulation, in the road network of the region [2]. Air emissions from road transport considered in this study are the exhaust emissions from combustion of fuel during vehicle movement. This is mainly SO2 （sulfur dioxide）, NOx （nitrogen oxides）, CO （carbon monoxide）, CO2 （carbon dioxide）, SP （suspended particulate） [3], VOC （volatile organic compounds）, benzene, lead Pb and cadmium. These emissions depend mainly on the technology of the vehicle （type, fuel, engine size, and age）, the vehicle speed, the engine temperature and ambient temperature [4].展开更多
A systematic investigation of the microstructure of CrA1CxN1-x coatings as a function of carbon contents was conducted. Quaternary CrA1CxN1-x coatings were deposited on Si wafers by a hybrid coating system combining a...A systematic investigation of the microstructure of CrA1CxN1-x coatings as a function of carbon contents was conducted. Quaternary CrA1CxN1-x coatings were deposited on Si wafers by a hybrid coating system combining an arc-ion plating technique and a DC reactive magnetron sputtering technique using Cr and AI targets in the Ar/N2/CH4 gaseous mixture. The effect of carbon content on microstructure of CrA1C^N~ x coatings was investigated with instrumental analyses of X-ray diffraction, X-ray photoelectron, and high-resolution transmission electron microscopy. The results show that the carbon content of CrA1CxN1-x coatings linearly increases with increasing CH4/（CH4/N2） gas flow rate ratio. The surface roughness of the CrA1CxN1-x coating layer decreases with the increase of carbon content.展开更多
Charcoal gasification could mitigate the energetic problems in the rural zones since these regions have considerable amounts of wood, which is the base of such a fuel available. This paper presents some CFD （computat...Charcoal gasification could mitigate the energetic problems in the rural zones since these regions have considerable amounts of wood, which is the base of such a fuel available. This paper presents some CFD （computational fluid dynamic） predictions of the experimental results obtained from the fixed bed gasification of charcoal made in a pilot-scale downdraft reactor using air, which was designed and built by the Research Group in Clean Development Mechanisms and Energy Management, from the National University of Colombia. The quality of the syngas obtained from the process was evaluated through the CO and CO2 percentages measured in its composition. The performance at various air flow rates （measured at the system entrance, through an analog flow meter） is evaluated with the help of 11 thermocouples, which give the information to create a temperature profile, and three load cells to measure the solid fuel conversion rate. To simulate the process, the information from temperature profile, charcoal proximate analysis, air flow meter and load cells were taken as inputs and the syngas composition was obtained as the result from the calculation. The domain was defined as 2D with an axis-symmetric description, using quads as mesh elements. The calculation and results were performed in a CFD commercial code widely used for this type of simulations： ANSYS FLUENT. The predictions made by the software were validated with the experimental results obtained in the laboratory.展开更多
The porous medium has an important effect on hydrate formation.In this paper,the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (...The porous medium has an important effect on hydrate formation.In this paper,the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (SDS) existing in the system.The results show that A-type zeolite can influence methane hydrate formation.At the temperature of 273.5 K and pressure of 8.3 MPa,the distilled water with A-type zeolite can form methane hydrate with gaseous methane in 12 hours.The formation process of the system with A-type zeolite was quite steady and the amount of A-type zeolite can influence the gas storage capacity significantly.The adding of A-type zeolite with 0.067 g·(g water)-1 into 2×10-3 g·g-1 SDS-water solution can increase the gas storage capacity,and the maximum increase rate was 31%.Simultaneously the promotion effect on hydrate formation of 3A-type zeolite is much more obvious than that of 5A-type zeolite when the water adding amounts are 0.033 g·g-1 and 0.067 g·g-1 at the experimental conditions.展开更多
The future change of September Arctic sea-ice volume,simulated by 30 state-of-the-art climate models from the Coupled Model Intercomparison Project Phase 5（CMIP5）,is examined,which depends on both ice extent and ice...The future change of September Arctic sea-ice volume,simulated by 30 state-of-the-art climate models from the Coupled Model Intercomparison Project Phase 5（CMIP5）,is examined,which depends on both ice extent and ice thickness.In comparison with the September sea-ice extent,the September sea-ice volume has larger spread in the historical simulation but faster convergence in the projection simulation,especially in the context of increasing greenhouse gas emissions.This indicates that the ice volume might be more sensitive to external forcings than the ice extent.Using the averaged projection of those climate models from the 30 CMIP5 models that can better reflect the ‘observed＇ sea-ice volume climatology and variability,it is shown that the September sea ice volume will decrease to ~3000 km3 in the early 2060 s,and then level off under a medium-mitigation scenario.However,it will drop to ~3000 km3 in the early 2040 s and reach a near-zero ice volume in the mid-2070 s under a high-emission scenario.With respect to the historical condition,the reduction of the ice volume,associated with increasing greenhouse gas emissions,is more rapid than that of the ice extent during the twenty-first century.展开更多
This study presents the first demonstration project in China for treatment of coal-bed methane(CBM) co-produced water and recycling.The work aims to provide a research and innovation base for solving the pollution pro...This study presents the first demonstration project in China for treatment of coal-bed methane(CBM) co-produced water and recycling.The work aims to provide a research and innovation base for solving the pollution problem of CBM extraction water.The reverse osmosis(RO) unit is applied to the treatment of CBM co-produced water.The results indicate that system operation is stable,the removal efficiency of the total dissolved solids(TDS) is as high as 97.98%,and Fe,Mn,and F-are almost completely removed.There is no suspended solids(SS) detected in the treated water.Furthermore,a model for the RO membrane separation process is developed to describe the quantitative relationship between key physical quantities-membrane length,flow velocity,salt concentration,driving pressure and water recovery rate,and the water recovery restriction equation based on mass balance is developed.This model provides a theoretical support for the RO system design and optimization.The TDS in the CBM co-produced water are removed to meet the "drinking water standards" and "groundwater quality standards" of China and can be used as drinking water,irrigation water,and livestock watering.In addition,the cost for treatment of CBM co-produced water is assessed,and the RO technology is an efficient and cost-effective treatment method to remove pollutants.展开更多
According to IPCC （Intergovemmental Panel on Climate Change） Fourth Report, carbon dioxide emissions from the combustion of fossil fuels have been identified as the major contributor to global warming and climate ch...According to IPCC （Intergovemmental Panel on Climate Change） Fourth Report, carbon dioxide emissions from the combustion of fossil fuels have been identified as the major contributor to global warming and climate change. One of the new approaches for capturing carbon dioxide and subsequently lowering the emissions is based on gas hydrate crystallization. Gas hydrates have a large capacity for the storage of gases which also resemble an attractive method for gas filtration. The basis of the separation is the selective partition of the target component between the hydrate phase and the gaseous phase. It is expected that carbon dioxide is preferentially encaged into the hydrate crystal phase compared to the other components. In the present paper, after a comparison of gas hydrates with existing capture technologies, a novel apparatus for gas hydrate production is illustrated and results of a first set of experimental applications of the reactor for CO2 hydrate formation and separation are presented. In particular, the effects of two different promoters were investigated. Results show that the reactor allows a good level of temperature control, resulting in rapid hydrate formation and mild operating conditions. Results are a basis for setting up a procedure for CO2 separation and capture.展开更多
文摘The sulfate-methane interface is an important biogeochemical identification interface for the areas with high methane flux and containing gas hydrate. Above the sulfate-methane interface, the sulfate concentration in the sediment is consumed progressively for the decomposition of the organic matter and anaerobic methane oxidation. Below the sulfate-methane interface, the methane concentration increases continuously with the depth. Based on the variation characters of the sulfate and methane concentration around the sulfate-methane interface, it is feasible to estimate the intensity of the methane flux, and thereafter to infer the possible occurrence of gas hydrate. The geochemical data of the pore water taken from the northern slope of the South China Sea show the sulfate-methane interface is relatively shallow, which indicates that this area has the high methane flux. It is considered that the high methane flux is most probably caused by the occurrence of underlying gas hydrate in the northern slope of the South China Sea.
文摘The refractive indices of disordered (Al xGa 1-x ) 0 51 In 0 49 P,which is grown by low-pressure organometallic vapor phase epitaxy and lattice-matched to GaAs substrate,have been determined by measuring their reflectance spectra when the wavelength ranges between 0 5 to 2 5 micrometer.A single-oscillator dispersion model is used to verify the experiment data and calculate the reflectance spectrum.The refractive indices are used to analyze the waveguide of strain quantum well GaInP/AlGaInP visible laser diode.The simulated far field pattern is consistent with the experimental results very well.
基金supported by the"Strategic Priority Research Program" of the Chinese Academy of Sciences (Grant No. XDA05040000)the National Natural Science Foundation of China (Grant Nos. 40775002 and 41175020)the National High Technology Research and Development Program of China (863 Program, Grant No. SQ2010AA1221583001)
文摘The hygroscopic properties of mixed aerosol particles are crucial for the application of remote sensing products of aerosol optical parameters in the study of air quality and climate at multiple scales. In this study, the authors investigated aerosol optical properties as a func tion of relative humidity （RH） for two representative me tropolises： Beijing and Hong Kong. In addition to the RH data, mass concentrations of PM10 （particulate matter up to 10 utm in diameter） and aerosol scattering extinction coefficient （aext） data were used. The relationship between the mass scattering extinction efficiency （MEE, defined as O＇ext/PMl0） and RH can be expressed by regression func tions asf= 1.52x ＋ 0.29 （re= 0.77）,f= 1.42x ＋ 1.53 （re= 0.58）,f= 1.19x ＋ 0.65 （re= 0.59）, andf= 1.58x ＋ 1.30 （re = 0.61） for spring, summer, autumn, and winter, respec tively, in Beijing. Here, f represents MEE, x represents I/（1-RH）, and the coefficients of determination are pre sented in parentheses. Conversely, in Hong Kong, the corresponding functions are f= 1.98x- 1.40 （r^2= 0.55）,f = 1.32x - 0.36 （r^2 = 0.26）,f= 1.87x - 0.65 （r^2 = 0.64）, and f= 2.39x - 1.47 （r^2 = 0.72）, respectively. The MEE values for Hong Kong at high RHs （RH 〉 70%） are higher than those for Beijing, except in summer; this suggests that aerosols in Hong Kong are more hygroscopic than those in Beijing for the other three seasons, but the aerosol hy groscopicity is similarly high in summer over both cities. This study describes the effects of moisture on aerosol scattering extinction coefficients and provides a potential method of studying atmospheric visibility and ground level air quality using some of the optical remote sensing products of satellites.
基金CSIRO Energy TechnologyChina Scholarship CouncilChina Fundamental Research Foundation for National University of China University of Geosciences (No.CUGL120258)
文摘Gas outbursts in underground mining occur under conditions of high gas desorption rate and gas content,combined with high stress regime, low coal strength and high Young's modulus. This combination of gas and stress factors occurs more often in deep mining. Hence, as the depth of mining increases, the potential for outburst increases. This study proposes a conceptual model to evaluate outburst potential in terms of an outburst indicator. The model was used to evaluate the potential for gas outburst in two mines, by comparing numerical simulations of gas flow behavior under typical stress regimes in an Australian gassy mine extracting a medium-volatile bituminous coal, and a Chinese gassy coal mine in Qinshui Basin(Shanxi province) extracting anthracite coal. We coupled the stress simulation program(FLAC3D) with the gas simulation program(SIMED II) to compute the stress and gas pressure and gas content distribution following development of a roadway into the targeted coal seams. The data from gas content and stress distribution were then used to quantify the intensity of energy release in the event of an outburst.
基金Supported by the National Natural Science Foundation of China （50706006） and the Science and Technology Development Program of Jilin Province （20040513）.
文摘The knowledge of flow regime is very important for quantifying the pressure drop, the stability and safety of two-phase flow systems. Based on image multi-feature fusion and support vector machine, a new method to identify flow regime in two-phase flow was presented. Firstly, gas-liquid two-phase flow images including bub- bly flow, plug flow, slug flow, stratified flow, wavy flow, annular flow and mist flow were captured by digital high speed video systems in the horizontal tube. The image moment invariants and gray level co-occurrence matrix texture features were extracted using image processing techniques. To improve the performance of a multiple classifier system, the rough sets theory was used for reducing the inessential factors. Furthermore, the support vector machine was trained by using these eigenvectors to reduce the dimension as flow regime samples, and the flow regime intelligent identification was realized. The test results showed that image features which were reduced with the rough sets theory could excellently reflect the difference between seven typical flow regimes, and successful training the support vector machine could quickly and accurately identify seven typical flow regimes of gas-liquid two-phase flow in the horizontal tube. Image multi-feature fusion method provided a new way to identify the gas-liquid two-phase flow, and achieved higher identification ability than that of single characteristic. The overall identification accuracy was 100%, and an estimate of the image processing time was 8 ms for online flow regime identification.
基金Acknowledgments： The work was supported by the National Nature Science Foundation of China （No. 50574046, 50164002） and National Natural Science Foundation of Major Research Projects （No. 90610035）, Natural Science Foundation of Yunnan Province （No. 2004E0058Q）, High School Doctoral Subject Special Science and Research Foundation of Ministry of Education （No. 20040674005）.
文摘Promoter MgO on 10% CeO2/Al2O3 oxygen carrier was investigated for direct partial oxidation of methane to syngas in molten salt. The MgO content of 0.5%, 1%, 2%, 3% and 4% on the 10%CeO2/Al2O3 oxygen carriers in experiments were prepared at the temperature of 750℃, respectively. The methane conversion, H2 and CO selectivity was measured on these prepared oxygen carriers at different reaction temperature. The results showed that the 3% MgO on 10%CeO2/Al2O3 had the best activity, and the CH4 conversion and CO selectivity reached 92.58% and 87.64% at 875℃, respectively. The effect of different calcination temperature on 3% MgO as promoter on 10% CeO2/Al2O3 oxygen carrier was investigated. The results of BET indicated that oxygen carrier had the largest surface area at 750℃. When the calcined temperature was too high there would be a negative effect on oxygen carrier activity.
基金supported by the research fund of the National Natural Science Foundation of China (21306162)the National Basic Research Program "973" Project of China (2010CB226903)Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province (AE201309)
文摘In this work, Zr-M(M=Cu, Mn, Ce) type sulfur transfer agent was prepared by impregnation method. Under the condition similar to that in the regenerator of FCC units, the influence of different active metal components and their contents on sulfur transfer agent were investigated. Moreover, the crystalline structure of sulfur transfer agent was characterized by X-ray diffraction(XRD) and Fourier transforms infrared spectroscopy(FT-IR). The result showed that the Zr-Mn sulfur transfer agent could effectively reduce the SO2 content in FCC regenerator flue gas, featuring high SO2 adsorption capacity. The sulfur transfer agent was inactivated in 40—60 min during the test. In the course of reduction reaction, after several reaction cycles, the formation of SO2 ceased and only H2 S was detected as the reduction product.
文摘Glycerol pyrolysis is carried out in a fixed bed reactor filled with alumina oxide. The packing material diameter was examined according to each one, but in general it was varied between 0.1-5.0 mm. The reaction temperature was varied in the range of 700-900 ℃, the reaction time from 10 to 50 min and flow rate of carrier gas from 0 to 60 mL/min. The process parameters listed above （factors） were used to evaluate the syngas production yield （response）. Also, syngas properties such as composition and heat value were evaluated. The experiments were carried out according to a 23 factorial design plus three central points. At last, a technical-economical analysis is carried out to examine the feasibility of syngas production from glycerol pyrolysis considering not only feedstock, catalyst and energy required costs but also conventional procedures used nowadays to produce syngas such as water electrolysis and natural gas catalytic reform.
基金Under the auspices of National Basic Research Program of China (No. 2012CB955800,2012CB955804)National Natural Science Foundation of China (No. 41171438)+2 种基金Foundation of Asia-Pacific Network for Global Change Research (No.EBLU2010-01NSY-Suneetha)Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA05050000)Science Foundation of Government of Henan Province & Ministry of Education (No. SBGJ090110,2010YBZR043)
文摘During the 15th Conference of the Parties （COP 15）, Parties agreed that reducing emissions from deforesta- tion and forest degradation and enhancing ＇removals of greenhouse gas emission by forests＇ （REDD＋） in developing countries through positive incentives under the United Nations Framework Convention on Climate Change （UNFCCC） was capable of dealing with global emissions. As REDD＋ seeks to lower emissions by stopping deforestation and for- est degradation with an international payment tier according to baseline scenarios, opportunities for ecosystem benefits such as slowing habitat fragmentation, conservation of forest biodiversity, soil conservation may be also part of this effort. The primary objective of this study is to evaluate ecosystem-based benefits of REDD＋, and to identify the rela- tionships with carbon stock changes. To achieve this goal, high resolution satellite images are combined with Normal- ized Difference Vegetation Index （NDVI） to identify historical deforestation in study area of Central Kalimantan, In- donesia. The carbon emissions for the period of 2000-2005 and 2005-2009 are 2.73 ×10^5 t CO2 and 1.47× 10^6 t CO2 respectively, showing an increasing trend in recent years. Dring 2005-2009, number of patches （NP）, patch density （PD）, mean shape index distribution （SHAPE_MN） increased 30.8%, 30.7% and 7.6%. Meanwhile, largest patch index （LPI）, mean area （AREA MN）, area-weighted mean of shape index distribution （SHAPE_AM）, neighbor distance （ENN_MN） and interspersion and juxtaposition index （IJI） decreased by 55.3%, 29.7%, 15.8%, 53.4% and 21.5% re- spectively. The area regarding as positive correlation between carbon emissions and soil erosion was approximately 8.9 x l03 ha corresponding to 96.0% of the changing forest. These results support the view that there are strong syner- gies among carbon loss, forest fragmentation and soil erosion in tropical forests. Such mechanism of REDD＋ is likely to present opportunities for multiple benefits that fall outside the scope of carbon stocks.
文摘The air quality directive （2008/50/EC （of the European Parliament and of the Council of 21 May 2008）） requires European Member States to design appropriate AQPs （air quality plans） for zones and agglomerations where the air quality does not comply with the limit values and to assess possible emission reduction measures to decrease concentration levels. The Portuguese agglomeration of Porto Litoral is one of the several European Union urban areas that had to develop and implement AQPs to reduce particulate matter （PM10）. The AQPs were initially designed based on a scenario approach and using an air quality model, which was applied over the study region for the reference situation with the current PM10 emissions, and for a reduction scenario with PM10 emissions re-estimated considering the implementation of abatement measures. Aiming to cost-efficiently optimize Porto Litoral PM10 abatement measures, the assessment procedure was repeated using an optimization approach based on the RIAT ＋ （regional integrated assessment tool ＋）. Porto Litoral urban area＇s technical and non-technical measures were characterized （including associated costs） and, through the application of the air quality model to 20 emissions abatement scenarios, S-R （source-receptor） relationships were created. This paper comparatively describes the air quality plans designed to improve PM10 levels in the Porto Litoral agglomeration based on both the scenario analysis and the optimization approach.
文摘The research works of methane concentration in water column of the Okhotsk Sea from 1984 to 2005 were reviewed.And some regularities of methane distribution in water column in the North-East Sakhalin slope of the Okhotsk Sea were concluded.
基金the support of the National Natural Science Foundation of China(Nos.51674158,51604168 and 51504142)the Natural Science Foundation of Shandong Province(No.ZR2016EEQ18)+2 种基金the SDUST Research Fund(No.2015JQJH105)the Qingdao Postdoctoral Applied Research Project(No.2015204)the Taishan Scholar Talent Team Support Plan for Advantaged&Unique Discipline Areas
文摘In this study, we selected 9 typical coal samples with different metamorphic grades as the study subjects,measured their initial 30-min gas desorption at 30℃ and different pressure using a self-developed gas adsorption/desorption device. Based on the characteristics of gas desorption from coal samples, we proposed a direct fitting method for measurement of gas content in coalbed, analyzed the effects of sampling time on the measurement results and determined the reasonable sampling time of coal samples with different metamorphic grades at different gas adsorption pressure at equilibrium. The results show that (1)the error of gas contents obtained using the direct fitting method relative to that obtained using indirect method is less than 10%, which meets the actual on-site requirements and verifies the feasibility of the direct fitting method;(2) when the relative error is controlled within ±10%, the reasonable sampling time of coal samples is linearly related to the gas adsorption pressure at equilibrium;(3) the reasonable sampling time of coal samples with the same metamorphic grade exhibits a shortening trend with increasing gas adsorption pressure at equilibrium;(4) for coal samples with similar gas adsorption pressure at equilibrium, the reasonable sampling time of coal samples displays a shortening trend with increasing metamorphic grade. Overall, the study provides a basis for improving the measurement accuracy of gas content in coalbed.
文摘In the Greater Casablanca, road transport is the second largest emissions source of gaseous pollutants and particles after the industry [ 1 ]. The emitters are mobile and include different categories of vehicles in circulation, in the road network of the region [2]. Air emissions from road transport considered in this study are the exhaust emissions from combustion of fuel during vehicle movement. This is mainly SO2 （sulfur dioxide）, NOx （nitrogen oxides）, CO （carbon monoxide）, CO2 （carbon dioxide）, SP （suspended particulate） [3], VOC （volatile organic compounds）, benzene, lead Pb and cadmium. These emissions depend mainly on the technology of the vehicle （type, fuel, engine size, and age）, the vehicle speed, the engine temperature and ambient temperature [4].
基金Project supported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, KoreaProject (2010-0001-226) supported by NCRC(National Core Research Center) Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology
文摘A systematic investigation of the microstructure of CrA1CxN1-x coatings as a function of carbon contents was conducted. Quaternary CrA1CxN1-x coatings were deposited on Si wafers by a hybrid coating system combining an arc-ion plating technique and a DC reactive magnetron sputtering technique using Cr and AI targets in the Ar/N2/CH4 gaseous mixture. The effect of carbon content on microstructure of CrA1C^N~ x coatings was investigated with instrumental analyses of X-ray diffraction, X-ray photoelectron, and high-resolution transmission electron microscopy. The results show that the carbon content of CrA1CxN1-x coatings linearly increases with increasing CH4/（CH4/N2） gas flow rate ratio. The surface roughness of the CrA1CxN1-x coating layer decreases with the increase of carbon content.
文摘Charcoal gasification could mitigate the energetic problems in the rural zones since these regions have considerable amounts of wood, which is the base of such a fuel available. This paper presents some CFD （computational fluid dynamic） predictions of the experimental results obtained from the fixed bed gasification of charcoal made in a pilot-scale downdraft reactor using air, which was designed and built by the Research Group in Clean Development Mechanisms and Energy Management, from the National University of Colombia. The quality of the syngas obtained from the process was evaluated through the CO and CO2 percentages measured in its composition. The performance at various air flow rates （measured at the system entrance, through an analog flow meter） is evaluated with the help of 11 thermocouples, which give the information to create a temperature profile, and three load cells to measure the solid fuel conversion rate. To simulate the process, the information from temperature profile, charcoal proximate analysis, air flow meter and load cells were taken as inputs and the syngas composition was obtained as the result from the calculation. The domain was defined as 2D with an axis-symmetric description, using quads as mesh elements. The calculation and results were performed in a CFD commercial code widely used for this type of simulations： ANSYS FLUENT. The predictions made by the software were validated with the experimental results obtained in the laboratory.
基金Supported by the National Natural Science Foundation of China （50876107）, the National Basic Research Program of China （2009CB219504）, NSFC-Guangdong Union Foundation （NSFC-U0733033） and CAS Program （KGCX2-YW-805）.
文摘The porous medium has an important effect on hydrate formation.In this paper,the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (SDS) existing in the system.The results show that A-type zeolite can influence methane hydrate formation.At the temperature of 273.5 K and pressure of 8.3 MPa,the distilled water with A-type zeolite can form methane hydrate with gaseous methane in 12 hours.The formation process of the system with A-type zeolite was quite steady and the amount of A-type zeolite can influence the gas storage capacity significantly.The adding of A-type zeolite with 0.067 g·(g water)-1 into 2×10-3 g·g-1 SDS-water solution can increase the gas storage capacity,and the maximum increase rate was 31%.Simultaneously the promotion effect on hydrate formation of 3A-type zeolite is much more obvious than that of 5A-type zeolite when the water adding amounts are 0.033 g·g-1 and 0.067 g·g-1 at the experimental conditions.
基金supported by the National Natural Science Foundation of China[grant numbers 41305097 and 41176169]the National Basic Research Program of China[973 program,grant number 2011CB309704]
文摘The future change of September Arctic sea-ice volume,simulated by 30 state-of-the-art climate models from the Coupled Model Intercomparison Project Phase 5（CMIP5）,is examined,which depends on both ice extent and ice thickness.In comparison with the September sea-ice extent,the September sea-ice volume has larger spread in the historical simulation but faster convergence in the projection simulation,especially in the context of increasing greenhouse gas emissions.This indicates that the ice volume might be more sensitive to external forcings than the ice extent.Using the averaged projection of those climate models from the 30 CMIP5 models that can better reflect the ‘observed＇ sea-ice volume climatology and variability,it is shown that the September sea ice volume will decrease to ~3000 km3 in the early 2060 s,and then level off under a medium-mitigation scenario.However,it will drop to ~3000 km3 in the early 2040 s and reach a near-zero ice volume in the mid-2070 s under a high-emission scenario.With respect to the historical condition,the reduction of the ice volume,associated with increasing greenhouse gas emissions,is more rapid than that of the ice extent during the twenty-first century.
基金Supported by the National Basic Research Program of China(2011ZX05060-0052009ZX05039-003)+2 种基金the National Natural Science Foundation of China(21106176)the President Fund of GUCAS(Y15101JY00)the National Science Foundation for Post-doctoral Scientists of China(20110490627)
文摘This study presents the first demonstration project in China for treatment of coal-bed methane(CBM) co-produced water and recycling.The work aims to provide a research and innovation base for solving the pollution problem of CBM extraction water.The reverse osmosis(RO) unit is applied to the treatment of CBM co-produced water.The results indicate that system operation is stable,the removal efficiency of the total dissolved solids(TDS) is as high as 97.98%,and Fe,Mn,and F-are almost completely removed.There is no suspended solids(SS) detected in the treated water.Furthermore,a model for the RO membrane separation process is developed to describe the quantitative relationship between key physical quantities-membrane length,flow velocity,salt concentration,driving pressure and water recovery rate,and the water recovery restriction equation based on mass balance is developed.This model provides a theoretical support for the RO system design and optimization.The TDS in the CBM co-produced water are removed to meet the "drinking water standards" and "groundwater quality standards" of China and can be used as drinking water,irrigation water,and livestock watering.In addition,the cost for treatment of CBM co-produced water is assessed,and the RO technology is an efficient and cost-effective treatment method to remove pollutants.
文摘According to IPCC （Intergovemmental Panel on Climate Change） Fourth Report, carbon dioxide emissions from the combustion of fossil fuels have been identified as the major contributor to global warming and climate change. One of the new approaches for capturing carbon dioxide and subsequently lowering the emissions is based on gas hydrate crystallization. Gas hydrates have a large capacity for the storage of gases which also resemble an attractive method for gas filtration. The basis of the separation is the selective partition of the target component between the hydrate phase and the gaseous phase. It is expected that carbon dioxide is preferentially encaged into the hydrate crystal phase compared to the other components. In the present paper, after a comparison of gas hydrates with existing capture technologies, a novel apparatus for gas hydrate production is illustrated and results of a first set of experimental applications of the reactor for CO2 hydrate formation and separation are presented. In particular, the effects of two different promoters were investigated. Results show that the reactor allows a good level of temperature control, resulting in rapid hydrate formation and mild operating conditions. Results are a basis for setting up a procedure for CO2 separation and capture.
