Direct growth of GaN films on Si(001) substrate at low temperatures (620~720℃) by electron cyclotron resonance (ECR) microwave plasma enhanced metalorganic chemical vapor deposition (PEMOCVD).The crystalline phase s...Direct growth of GaN films on Si(001) substrate at low temperatures (620~720℃) by electron cyclotron resonance (ECR) microwave plasma enhanced metalorganic chemical vapor deposition (PEMOCVD).The crystalline phase structures of the films are investigated.The results of high resolution transmission electron microscopy (HRTEM) and X ray diffraction (XRD) indicate that high c axis oriented crystalline wurtzite GaN is grown on Si(001) but there is an amorphous layer formed naturally at GaN/Si interface.Both faces of the amorphous layer are flat and sharp,and the thickness of the layer is 2nm approximately cross the interface.The analysis supports that β GaN phase is not formed owing to the N x Si y amorphous layer induced by the reaction between N and Si during the initial nucleation stage.The results of XRD and atomic force microscopy (AFM) indicate that the conditions of substrate surface cleaned in situ by hydrogen plasma,GaN initial nucleation and subsequent growth are very important for the crystalline quality of GaN films.展开更多
In this study, the flow characteristics and behaviors of virgin and recycled Inconel powder for powder-bed additive manufacturing (AM) were studied using different powder characterization techniques. The results rev...In this study, the flow characteristics and behaviors of virgin and recycled Inconel powder for powder-bed additive manufacturing (AM) were studied using different powder characterization techniques. The results revealed that the particle size distribution (PSD) for the selective laser melting (SLM) process is typically in the range from 15 μm to 63 μm. The flow rate of virgin Inconel powder is around 28 s·(50 g)^-1. In addition, the packing density was found to be 60%. The rheological test results indicate that the virgin powder has reasonably good flowability compared with the recycled powder. The inter-relation between the powder characteristics is discussed herein. A propeller was successfully printed using the powder. The results suggest that Inconel powder is suitable for AM and can be a good reference for researchers who attempt to pro- duce AM powders.展开更多
The data of 16o national meteorological observatory stations including the long-term monthly temperature data in China were analyzed to study the seasonal variation of the spatial temperature structures across China i...The data of 16o national meteorological observatory stations including the long-term monthly temperature data in China were analyzed to study the seasonal variation of the spatial temperature structures across China in the past half century. It is found that temperature structures differ between seasons: a latitude temperature pattern in winter and a landform temperature pattern in summer, which indicate that the effect of landform on temperature structure is much stronger in summer than that in winter and the effect of latitudinal temperature is much stronger in winter than that in summer. The mechanisms of the seasonal difference in temperature structures are also discussed in this paper.展开更多
The gasification industries make use of biomass residue as feedstock to produce synthesis gas,but the gasification of this waste biomass generates tons of ash everyday.Performance properties and agglomeration behavior...The gasification industries make use of biomass residue as feedstock to produce synthesis gas,but the gasification of this waste biomass generates tons of ash everyday.Performance properties and agglomeration behavior of corncob ash(CCA) collected from the gasification of corncobs in a pilot-scale gasification station were investigated by using some experimental methods.Based on the chemical composition results,the agglomeration tendency of CCA from combustion and gasification process was also analyzed.Chemical analysis shows that the fly ash is mainly composed of inorganic matters formed by K,Mg,Ca,Na,Fe,Al,S,etc.The agglomeration characteristics indicate that the slagging degree increases with the increase of ashing temperature,and the slagging tendency of these CCA samples from gasification or combustion is different with various slagging indices.All CCA samples from combustion or gasification can cause slagging/fouling problems in thermal conversion systems.The applications of CCA are closely related to its performances,and CCA has the potential to be used in various fields,for example,as a material for ceramic products and activated carbon,as an adsorbent,as a crude fertilizer,and as a structural material.展开更多
The time evolution of coal structure during low temperature oxidation was investigated by oxidizing coal samples in air at 120℃ for periods of up to 14 days. The structure of the oxidized coal samples was char- acter...The time evolution of coal structure during low temperature oxidation was investigated by oxidizing coal samples in air at 120℃ for periods of up to 14 days. The structure of the oxidized coal samples was char- acterized by Fourier transform infrared spectroscopy (FFIR) and curve fitting analysis. The results show that carboxyl and ether groups are the main oxygen containing moieties in oxidized coal. Ethers are most abundant during the first 3 days of oxidation, thereafter carboxyl groups predominate. The content of carboxyl and ester functionality increases with oxidation time. The other oxygen containing groups vary in concentration over time. The amount of hydroxyl groups first decreases then increases and finally decrease again during the oxidation. The aliphatic structure and the degree of branching of the aliphatic chains is reduced as the oxidation proceeds. The proportion of aromatic structure increases with oxida- tion time. Obvious decomposition of aromatic rings occurs after about 9 days of oxidation. The aryl ester bands and the CH3/CH2 ratio both have a good linear relationship to oxidation time.展开更多
Efforts to speed up China's coal bed methane (CBM) exploration developments related to production safety, optimization of energy structures, prevention of energy waste and reduction of greenhouse gas emissions are...Efforts to speed up China's coal bed methane (CBM) exploration developments related to production safety, optimization of energy structures, prevention of energy waste and reduction of greenhouse gas emissions are all of great significance. In order to strengthen CBM exploration and development in China and to encourage increased growth in the CBM industry, we firstly give a general overview of the recent technological innovations and other developments in CBM exploration in the U.S., Canada and other countries. Using this background information as the starting point, we further present observations and analyses of CBM exploration and development, preferential policies, technical support and implications of R&D for CBM development in China. The results show that the problems related to CBM exploration technology development and lack of a complete set of management policies are still the major issues slowing down the growth of domestic CBM industry. Development of resource exploration and technology, R&D and establishment of favorable government policy to support the industry and the creation of a relevant information platform, etc. are finally recommended.展开更多
C1 chemistry is the essence of coal chemistry and natural gas chemistry. Catalytic methods to efficiently convert C1 molecules into fuels and chemicals have been extensively studied. Syngas(CO +H_2) conversion is t...C1 chemistry is the essence of coal chemistry and natural gas chemistry. Catalytic methods to efficiently convert C1 molecules into fuels and chemicals have been extensively studied. Syngas(CO +H_2) conversion is the most important industrial reaction system in C1 chemistry, and Fe and Co catalysts, two major industrial catalysts, have been the focus of fundamental research and industrial application. In the last decade, considerable research efforts have been devoted to discoveries concerning catalyst structure and increasing market demands for olefins and oxygenates. Since the development of efficient catalysts would strongly benefit from catalyst design and the establishment of a new reaction system, this review comprehensively overviews syngas conversion in three main reactions, highlights the advances recently made and the challenges that remain open, and will stimulate future research activities. The first part of the review summarizes the breakthroughs in Fischer-Tropsch synthesis regarding the optimization of activity and stability, determination of the active phase, and mechanistic studies. The second part overviews the modulation of catalytic structure and product selectivity for Fischer-Tropsch to olefins(FTO). Catalysts designed to produce higher alcohols, as well as to tune product selectivity in C1 chemistry, are described in the third section. Finally, present challenges in syngas conversion are proposed, and the solutions and prospects are discussed from the viewpoint of fundamental research and practical application. This review summarizes the latest advances in the design, preparation, and application of Fe/Co-based catalysts toward syngas conversion and presents the challenges and future directions in producing value-added fuels.展开更多
This study discusses high-carbon characteristics, the unsustainability of China's development, and the fact that China needs to transform its development mode. China's low-carbon transition must include indust...This study discusses high-carbon characteristics, the unsustainability of China's development, and the fact that China needs to transform its development mode. China's low-carbon transition must include industry structure adjustment, energy saving and efficiency increases, energy structure improvement, carbon sink development, adaptation capability, and low-carbon pilot schemes.Low-carbon urbanization is a key measure in China's low-carbon transition. China's urbanization faces high-carbon risks. Thus, this study presents a roadmap for transforming urbanization into a low-carbon one. The transition to low-carbon urbanization is a common trend in the developing world. There is a lot of room for international cooperation.展开更多
Palm kernel shell(PKS)biochars with different levels of carbon conversion were initially prepared using a tube furnace,after which the reactivity of each sample was assessed with a thermogravimetric analyzer under a C...Palm kernel shell(PKS)biochars with different levels of carbon conversion were initially prepared using a tube furnace,after which the reactivity of each sample was assessed with a thermogravimetric analyzer under a CO_2 atmosphere.The pore structure and carbon ordering of each biochar also examined,employing a surface area analyzer and a Raman spectroscopy.Thermogravimetric results showed that the gasification index R_sof the PKS biochar decreased from 0.0305 min^(-1) at carbon conversion(x)=20% to 0.0278 min^(-1)at x=40%.The expansion of micropores was the dominant process during the pore structure evolution,ad mesopores with sizes ranging from 6 to 20,48 to 50 nm were primarily generated during gasification under a CO_2/H_2O mixture.The proportion of amorphous carbon in the PKS biochar decreased significantly as x increased,suggesting that the proportion of ordered carbon was increased during the CO_2/H_2O mixed gasification.A significantly reduced total reaction time was observed when employing a CO_2/intermittent H_2O process along with an 83.46% reduction in the steam feed,compared with the amount required using a CO_2/H_2O atmosphere.展开更多
In this study, the structures and evolutions of moderate(MO) explosive cyclones(ECs) over the Northwestern Pacific(NWP) and Northeastern Pacific(NEP) are investigated and compared using composite analysis with cyclone...In this study, the structures and evolutions of moderate(MO) explosive cyclones(ECs) over the Northwestern Pacific(NWP) and Northeastern Pacific(NEP) are investigated and compared using composite analysis with cyclone-relative coordinates. Final Operational Global Analysis data gathered during the cold seasons(October–April) of the 15 years from 2000 to 2015 are used. The results indicate that MO NWP ECs have strong baroclinicity and abundant latent heat release at low levels and strong upper-level forcing, which favors explosive cyclogenesis. The rapid development of MO NEP ECs results from their interaction with a northern cyclone and a large middle-level advection of cyclonic vorticity. The structural differences between MO NWP ECs and MO NEP ECs are significant. This results from their specific large-scale atmospheric and oceanic environments. MO NWP ECs usually develop rapidly in the east and southeast of the Japan Islands; the intrusion of cold dry air from the East Asian continent leads to strong baroclinicity, and the Kuroshio/Kuroshio Extension provides abundant latent heat release at low levels. The East Asian subtropical westerly jet stream supplies strong upper-level forcing. While MO NEP ECs mainly occur over the NEP, the low-level baroclinicity, upper-level jet stream, and warm ocean currents are relatively weaker. The merged cyclone associated with a strong middle-level trough transports large cyclonic vorticity to MO NEP ECs, which favors their rapid development.展开更多
A new silica sol binder was obtained by mixing the acid-modified aluminium sulfate and water glass. The effect of SiO2 concentration in sodium silicate, pH value and polymerization was investigated. The new silica sol...A new silica sol binder was obtained by mixing the acid-modified aluminium sulfate and water glass. The effect of SiO2 concentration in sodium silicate, pH value and polymerization was investigated. The new silica sol binder, which possessed abundant pore volume and suitable acid amount, was an ideal component for preparing cracking catalyst. As a result, the corresponding catalyst comprising the new binder showed excellent performance. Compared with the reference sample, the liquefied petroleum gas(LPG) and propylene yield obtained over this catalyst increased by 3.49 and 1.20 percentage points, respectively. The perfect pore structure and suitable Lewis acid amount of new silica sol were the possible reason leading to its outstanding performance.展开更多
Organizational ethical climate is an effective way to solve organizational ethical problems and dilemmas. Therefore study on our organizational ethical climate has the great significance to solve ethical problems and ...Organizational ethical climate is an effective way to solve organizational ethical problems and dilemmas. Therefore study on our organizational ethical climate has the great significance to solve ethical problems and dilemmas faced by the organization and staff. Through semi-structured interview, structural interview and questionnaire survey and other methods this study gets to understand internal structural elements of organizational ethical climate under Chinese cultural background, and constructs organizational ethical climate questionnaire, which has good reliability and validity; carries out surveys in large scale by using the revised questionnaire, and recycles 709 valid questionnaires. The results of exploratory factor analysis and confirmatory factor analysis show that Chinese organizational ethical climate' s internal structure includes five factors: egoism, altruism, independence orientated, organizational system orientated, and law and code orientated.展开更多
As well as shock wave and bubble pulse loading, cavitation also has very significant influences on the dynamic response of surface ships and other near-surface marine structures to underwater explosive loadings. In th...As well as shock wave and bubble pulse loading, cavitation also has very significant influences on the dynamic response of surface ships and other near-surface marine structures to underwater explosive loadings. In this paper, the acoustic-structure coupling method embedded in ABAQUS is adopted to do numerical analysis of underwater explosion considering cavitation. Both the shape of bulk cavitation region and local cavitation region are obtained, and they are in good agreement with analytical results. The duration of reloading is several times longer than that of a shock wave. In the end, both the single computation and parallel computation of the cavitation effect on the dynamic responses of a full-scale ship are presented, which proved that reloading caused by cavitation is non-ignorable. All these results are helpful in understanding underwater explosion cavitation effects.展开更多
It is a consensus of international community to promote the development of low carbon economy in order to face the challenges of climate change. According to the features of nuclear energy, the greenhouse gas (GHG) ...It is a consensus of international community to promote the development of low carbon economy in order to face the challenges of climate change. According to the features of nuclear energy, the greenhouse gas (GHG) emission of nuclear energy chain and other energy chain are compared and analyzed, and the results indicate that the GHG emission of nuclear power chain is the least in all types of power generation. The status of nuclear power development and the potential benefit in GHGs emission reduction by developing nuclear power in China are also analyzed. Active nuclear power development is a smart choice for constructing low-carbon energy structure and for addressing global climate changes in China.展开更多
In this work,a comprehensive comparison regarding the impacts of M(M=Cu,Co,Mn)substitution for Ni on the structures and the hydrogen storage kinetics of the nanocrystalline and amorphous Mg20Ni10-xMx(M=Cu,Co,Mn; x=0-4...In this work,a comprehensive comparison regarding the impacts of M(M=Cu,Co,Mn)substitution for Ni on the structures and the hydrogen storage kinetics of the nanocrystalline and amorphous Mg20Ni10-xMx(M=Cu,Co,Mn; x=0-4)alloys prepared by melt spinning has been carried out.The analysis of XRD and TEM reveals that the as-spun(M=None,Cu)alloys display an entire nanocrystalline structure,whereas the as-spun(M=Co,Mn)alloys hold a mixed structure of nanocrystalline and amorphous structure when M content x=4,indicating that the substitution of M(M=Co,Mn)for Ni facilitates the glass formation in the Mg2Ni-type alloy.Besides,all the as-spun alloys have a major phase of Mg2Ni but M(M=Co,Mn)substitution brings on the formation of some secondary phases,MgCo2 and Mg phases for M=Co as well as MnNi and Mg phases for M=Mn.Based upon the measurements of the automatic Sieverts apparatus and the automatic galvanostatic system,the impacts engendered by M(M=Cu,Co,Mn)substitution on the gaseous and electrochemical hydrogen storage kinetics of the alloys appear to be evident.The gaseous hydriding kinetics of the alloys first rises and then declines with the growing of M(M=Cu,Co,Mn)content.Particularly,the M(M= Mn)substitution results in a sharp drop in the hydriding kinetics when x=4.The M(M=Cu,Co,Mn)substitution ameliorates the dehydriding kinetics dramatically in the order(M=Co)>(M=Mn)>(M=Cu).The electrochemical kinetics of the alloys visibly grows with M content rising for(M=Cu,Co),while it first increases and then declines for(M=Mn).展开更多
文摘Direct growth of GaN films on Si(001) substrate at low temperatures (620~720℃) by electron cyclotron resonance (ECR) microwave plasma enhanced metalorganic chemical vapor deposition (PEMOCVD).The crystalline phase structures of the films are investigated.The results of high resolution transmission electron microscopy (HRTEM) and X ray diffraction (XRD) indicate that high c axis oriented crystalline wurtzite GaN is grown on Si(001) but there is an amorphous layer formed naturally at GaN/Si interface.Both faces of the amorphous layer are flat and sharp,and the thickness of the layer is 2nm approximately cross the interface.The analysis supports that β GaN phase is not formed owing to the N x Si y amorphous layer induced by the reaction between N and Si during the initial nucleation stage.The results of XRD and atomic force microscopy (AFM) indicate that the conditions of substrate surface cleaned in situ by hydrogen plasma,GaN initial nucleation and subsequent growth are very important for the crystalline quality of GaN films.
基金financial support provided by A*STAR Additive Manufacturing Centre (AMC) Initiative: Work package 1-High temperature materials development for 3D additive manufacturing (142680088)
文摘In this study, the flow characteristics and behaviors of virgin and recycled Inconel powder for powder-bed additive manufacturing (AM) were studied using different powder characterization techniques. The results revealed that the particle size distribution (PSD) for the selective laser melting (SLM) process is typically in the range from 15 μm to 63 μm. The flow rate of virgin Inconel powder is around 28 s·(50 g)^-1. In addition, the packing density was found to be 60%. The rheological test results indicate that the virgin powder has reasonably good flowability compared with the recycled powder. The inter-relation between the powder characteristics is discussed herein. A propeller was successfully printed using the powder. The results suggest that Inconel powder is suitable for AM and can be a good reference for researchers who attempt to pro- duce AM powders.
基金supported NKBRSF,PR China,No.2002CB111507The National Key of Science and Technology,No.2004BA508B22+2 种基金the Chinese National Natural Science Foundation(90302006,90511026)the Hundred Talents Program(2004401,KZCX3-SW-339)of the Chinese Academy of Sciencesthe Project for 0utstanding Scientists(40121101)of the National Natural Science Foundation of China.
文摘The data of 16o national meteorological observatory stations including the long-term monthly temperature data in China were analyzed to study the seasonal variation of the spatial temperature structures across China in the past half century. It is found that temperature structures differ between seasons: a latitude temperature pattern in winter and a landform temperature pattern in summer, which indicate that the effect of landform on temperature structure is much stronger in summer than that in winter and the effect of latitudinal temperature is much stronger in winter than that in summer. The mechanisms of the seasonal difference in temperature structures are also discussed in this paper.
基金Project(2013020137)supported by the Natural Science Foundation of Liaoning Province,ChinaProject(2015-36)supported by Rural Energy Comprehensive Construction Foundation of the Ministry of Agriculture,China
文摘The gasification industries make use of biomass residue as feedstock to produce synthesis gas,but the gasification of this waste biomass generates tons of ash everyday.Performance properties and agglomeration behavior of corncob ash(CCA) collected from the gasification of corncobs in a pilot-scale gasification station were investigated by using some experimental methods.Based on the chemical composition results,the agglomeration tendency of CCA from combustion and gasification process was also analyzed.Chemical analysis shows that the fly ash is mainly composed of inorganic matters formed by K,Mg,Ca,Na,Fe,Al,S,etc.The agglomeration characteristics indicate that the slagging degree increases with the increase of ashing temperature,and the slagging tendency of these CCA samples from gasification or combustion is different with various slagging indices.All CCA samples from combustion or gasification can cause slagging/fouling problems in thermal conversion systems.The applications of CCA are closely related to its performances,and CCA has the potential to be used in various fields,for example,as a material for ceramic products and activated carbon,as an adsorbent,as a crude fertilizer,and as a structural material.
基金supported by the Shaanxi Provincial Project of Special Foundation of Key Disciplinesthe Scientific Research Program Funded by Shaanxi Provincial Education Commission (No. 09JK583)the Seed Fund of Xi’an University of Science and Technology (No. 200745)
文摘The time evolution of coal structure during low temperature oxidation was investigated by oxidizing coal samples in air at 120℃ for periods of up to 14 days. The structure of the oxidized coal samples was char- acterized by Fourier transform infrared spectroscopy (FFIR) and curve fitting analysis. The results show that carboxyl and ether groups are the main oxygen containing moieties in oxidized coal. Ethers are most abundant during the first 3 days of oxidation, thereafter carboxyl groups predominate. The content of carboxyl and ester functionality increases with oxidation time. The other oxygen containing groups vary in concentration over time. The amount of hydroxyl groups first decreases then increases and finally decrease again during the oxidation. The aliphatic structure and the degree of branching of the aliphatic chains is reduced as the oxidation proceeds. The proportion of aromatic structure increases with oxida- tion time. Obvious decomposition of aromatic rings occurs after about 9 days of oxidation. The aryl ester bands and the CH3/CH2 ratio both have a good linear relationship to oxidation time.
基金the continuous supply of funds to the National Science and Technology Major Project-Developing Great Oil & Gas Field and Coal Bed Gas (No. 2008ZX05)
文摘Efforts to speed up China's coal bed methane (CBM) exploration developments related to production safety, optimization of energy structures, prevention of energy waste and reduction of greenhouse gas emissions are all of great significance. In order to strengthen CBM exploration and development in China and to encourage increased growth in the CBM industry, we firstly give a general overview of the recent technological innovations and other developments in CBM exploration in the U.S., Canada and other countries. Using this background information as the starting point, we further present observations and analyses of CBM exploration and development, preferential policies, technical support and implications of R&D for CBM development in China. The results show that the problems related to CBM exploration technology development and lack of a complete set of management policies are still the major issues slowing down the growth of domestic CBM industry. Development of resource exploration and technology, R&D and establishment of favorable government policy to support the industry and the creation of a relevant information platform, etc. are finally recommended.
文摘C1 chemistry is the essence of coal chemistry and natural gas chemistry. Catalytic methods to efficiently convert C1 molecules into fuels and chemicals have been extensively studied. Syngas(CO +H_2) conversion is the most important industrial reaction system in C1 chemistry, and Fe and Co catalysts, two major industrial catalysts, have been the focus of fundamental research and industrial application. In the last decade, considerable research efforts have been devoted to discoveries concerning catalyst structure and increasing market demands for olefins and oxygenates. Since the development of efficient catalysts would strongly benefit from catalyst design and the establishment of a new reaction system, this review comprehensively overviews syngas conversion in three main reactions, highlights the advances recently made and the challenges that remain open, and will stimulate future research activities. The first part of the review summarizes the breakthroughs in Fischer-Tropsch synthesis regarding the optimization of activity and stability, determination of the active phase, and mechanistic studies. The second part overviews the modulation of catalytic structure and product selectivity for Fischer-Tropsch to olefins(FTO). Catalysts designed to produce higher alcohols, as well as to tune product selectivity in C1 chemistry, are described in the third section. Finally, present challenges in syngas conversion are proposed, and the solutions and prospects are discussed from the viewpoint of fundamental research and practical application. This review summarizes the latest advances in the design, preparation, and application of Fe/Co-based catalysts toward syngas conversion and presents the challenges and future directions in producing value-added fuels.
文摘This study discusses high-carbon characteristics, the unsustainability of China's development, and the fact that China needs to transform its development mode. China's low-carbon transition must include industry structure adjustment, energy saving and efficiency increases, energy structure improvement, carbon sink development, adaptation capability, and low-carbon pilot schemes.Low-carbon urbanization is a key measure in China's low-carbon transition. China's urbanization faces high-carbon risks. Thus, this study presents a roadmap for transforming urbanization into a low-carbon one. The transition to low-carbon urbanization is a common trend in the developing world. There is a lot of room for international cooperation.
基金Supported by the Key Project of the Natural Science Foundation of Shandong Province(ZR2015QZ02)the Key Research&Development Program of Shandong Province(2016GSF117005)+1 种基金the introduction of scientific and technological innovation team of Ningxia Hui Autonomous Region(2016)Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2017-K22)
文摘Palm kernel shell(PKS)biochars with different levels of carbon conversion were initially prepared using a tube furnace,after which the reactivity of each sample was assessed with a thermogravimetric analyzer under a CO_2 atmosphere.The pore structure and carbon ordering of each biochar also examined,employing a surface area analyzer and a Raman spectroscopy.Thermogravimetric results showed that the gasification index R_sof the PKS biochar decreased from 0.0305 min^(-1) at carbon conversion(x)=20% to 0.0278 min^(-1)at x=40%.The expansion of micropores was the dominant process during the pore structure evolution,ad mesopores with sizes ranging from 6 to 20,48 to 50 nm were primarily generated during gasification under a CO_2/H_2O mixture.The proportion of amorphous carbon in the PKS biochar decreased significantly as x increased,suggesting that the proportion of ordered carbon was increased during the CO_2/H_2O mixed gasification.A significantly reduced total reaction time was observed when employing a CO_2/intermittent H_2O process along with an 83.46% reduction in the steam feed,compared with the amount required using a CO_2/H_2O atmosphere.
基金the National Natural Science Foundation of China for financial support (Nos. 41275049 and 41775042)
文摘In this study, the structures and evolutions of moderate(MO) explosive cyclones(ECs) over the Northwestern Pacific(NWP) and Northeastern Pacific(NEP) are investigated and compared using composite analysis with cyclone-relative coordinates. Final Operational Global Analysis data gathered during the cold seasons(October–April) of the 15 years from 2000 to 2015 are used. The results indicate that MO NWP ECs have strong baroclinicity and abundant latent heat release at low levels and strong upper-level forcing, which favors explosive cyclogenesis. The rapid development of MO NEP ECs results from their interaction with a northern cyclone and a large middle-level advection of cyclonic vorticity. The structural differences between MO NWP ECs and MO NEP ECs are significant. This results from their specific large-scale atmospheric and oceanic environments. MO NWP ECs usually develop rapidly in the east and southeast of the Japan Islands; the intrusion of cold dry air from the East Asian continent leads to strong baroclinicity, and the Kuroshio/Kuroshio Extension provides abundant latent heat release at low levels. The East Asian subtropical westerly jet stream supplies strong upper-level forcing. While MO NEP ECs mainly occur over the NEP, the low-level baroclinicity, upper-level jet stream, and warm ocean currents are relatively weaker. The merged cyclone associated with a strong middle-level trough transports large cyclonic vorticity to MO NEP ECs, which favors their rapid development.
基金the Department of Science and Technology Management of PetroChina for providing financial support
文摘A new silica sol binder was obtained by mixing the acid-modified aluminium sulfate and water glass. The effect of SiO2 concentration in sodium silicate, pH value and polymerization was investigated. The new silica sol binder, which possessed abundant pore volume and suitable acid amount, was an ideal component for preparing cracking catalyst. As a result, the corresponding catalyst comprising the new binder showed excellent performance. Compared with the reference sample, the liquefied petroleum gas(LPG) and propylene yield obtained over this catalyst increased by 3.49 and 1.20 percentage points, respectively. The perfect pore structure and suitable Lewis acid amount of new silica sol were the possible reason leading to its outstanding performance.
文摘Organizational ethical climate is an effective way to solve organizational ethical problems and dilemmas. Therefore study on our organizational ethical climate has the great significance to solve ethical problems and dilemmas faced by the organization and staff. Through semi-structured interview, structural interview and questionnaire survey and other methods this study gets to understand internal structural elements of organizational ethical climate under Chinese cultural background, and constructs organizational ethical climate questionnaire, which has good reliability and validity; carries out surveys in large scale by using the revised questionnaire, and recycles 709 valid questionnaires. The results of exploratory factor analysis and confirmatory factor analysis show that Chinese organizational ethical climate' s internal structure includes five factors: egoism, altruism, independence orientated, organizational system orientated, and law and code orientated.
基金Foundation item:Supported by the National Natural Science Foundation of China (Grant No. 50921001), National Key Basic Research Special Foundation of China (Grant No. 2010CB832704), Scientific Project for High-tech Ships: Key Technical Research on the Semi-planning Hybrid Fore-body Trimaran, Doctoral Research Foundation of Liaoning Province (Grant No. 20091012).
文摘As well as shock wave and bubble pulse loading, cavitation also has very significant influences on the dynamic response of surface ships and other near-surface marine structures to underwater explosive loadings. In this paper, the acoustic-structure coupling method embedded in ABAQUS is adopted to do numerical analysis of underwater explosion considering cavitation. Both the shape of bulk cavitation region and local cavitation region are obtained, and they are in good agreement with analytical results. The duration of reloading is several times longer than that of a shock wave. In the end, both the single computation and parallel computation of the cavitation effect on the dynamic responses of a full-scale ship are presented, which proved that reloading caused by cavitation is non-ignorable. All these results are helpful in understanding underwater explosion cavitation effects.
基金supported by the consulting project of Chinese Academy of Engineering entitled "The Key Issues of GHGs Emission for Different Power Energy in China"
文摘It is a consensus of international community to promote the development of low carbon economy in order to face the challenges of climate change. According to the features of nuclear energy, the greenhouse gas (GHG) emission of nuclear energy chain and other energy chain are compared and analyzed, and the results indicate that the GHG emission of nuclear power chain is the least in all types of power generation. The status of nuclear power development and the potential benefit in GHGs emission reduction by developing nuclear power in China are also analyzed. Active nuclear power development is a smart choice for constructing low-carbon energy structure and for addressing global climate changes in China.
基金Projects(51161015,51371094)supported by National Natural Science Foundations of ChinaProject(2011ZD10)supported by Natural Science Foundation of Inner Mongolia,China
文摘In this work,a comprehensive comparison regarding the impacts of M(M=Cu,Co,Mn)substitution for Ni on the structures and the hydrogen storage kinetics of the nanocrystalline and amorphous Mg20Ni10-xMx(M=Cu,Co,Mn; x=0-4)alloys prepared by melt spinning has been carried out.The analysis of XRD and TEM reveals that the as-spun(M=None,Cu)alloys display an entire nanocrystalline structure,whereas the as-spun(M=Co,Mn)alloys hold a mixed structure of nanocrystalline and amorphous structure when M content x=4,indicating that the substitution of M(M=Co,Mn)for Ni facilitates the glass formation in the Mg2Ni-type alloy.Besides,all the as-spun alloys have a major phase of Mg2Ni but M(M=Co,Mn)substitution brings on the formation of some secondary phases,MgCo2 and Mg phases for M=Co as well as MnNi and Mg phases for M=Mn.Based upon the measurements of the automatic Sieverts apparatus and the automatic galvanostatic system,the impacts engendered by M(M=Cu,Co,Mn)substitution on the gaseous and electrochemical hydrogen storage kinetics of the alloys appear to be evident.The gaseous hydriding kinetics of the alloys first rises and then declines with the growing of M(M=Cu,Co,Mn)content.Particularly,the M(M= Mn)substitution results in a sharp drop in the hydriding kinetics when x=4.The M(M=Cu,Co,Mn)substitution ameliorates the dehydriding kinetics dramatically in the order(M=Co)>(M=Mn)>(M=Cu).The electrochemical kinetics of the alloys visibly grows with M content rising for(M=Cu,Co),while it first increases and then declines for(M=Mn).