The aerodynamic behavior of tens of axial flow fans incorporated with air-cooled condensers in a power plant is different from that of an individual fan.Investigation of the aerodynamic characteristics of axial flow f...The aerodynamic behavior of tens of axial flow fans incorporated with air-cooled condensers in a power plant is different from that of an individual fan.Investigation of the aerodynamic characteristics of axial flow fan array benefits its design optimization and running regulation.Based on a representative 2600 MW direct-dry cooling power plant,the flow rate of each fan and the overall flow rate of the fan array are obtained in the absence of ambient wind and at various wind speeds and directions,using CFD simulation.The cluster factor of each fan and the average cluster factor of the fan array are calculated and analyzed.Results show that the cluster factors are different from each other and that the cluster effect with ambient wind is significantly different from the cluster effect with no wind.The fan at the periphery of the array or upwind of the ambient wind generally has a small cluster factor.The average cluster factor of the array decreases with the increasing wind speeds and also varies widely with wind direction.The cluster effect of the axial flow fan array can be applied to optimize the design and operation of air-cooled condensers in a power plant.展开更多
The geometric and electronic properties of some hydrogenated silicon clusters in the presence of oxygen on the surface have been investigated.The density functional theory with generalized gradient approximation funct...The geometric and electronic properties of some hydrogenated silicon clusters in the presence of oxygen on the surface have been investigated.The density functional theory with generalized gradient approximation functional was applied in our calculations.By calculating the total energy,the double bond Si=O is shown to be more stable than the bridge bond Si-O-Si for large size oxidized clusters.The results of Mulliken population analysis indicate that a so-called passivation effect is enhanced by oxidization effects.From the energy band structures and density of states,we find that some localized states are induced by the p-orbital of O atom mainly and reduce the energy gaps substantially.展开更多
Taking Chongzuo City of Guangxi Zhuang Autonomous Region as an example, the employment effect of the resource-abundant industrial cluster in southwestern Guangxi Province is analyzed according to the data from the Cho...Taking Chongzuo City of Guangxi Zhuang Autonomous Region as an example, the employment effect of the resource-abundant industrial cluster in southwestern Guangxi Province is analyzed according to the data from the Chongzuo Statistical Yearbook , Guangxi Statistical Yearbook from 2003 to 2008 and the data from the relevant sections of Chongzuo City, and the four employment effects of industrial cluster--the spatial expansion effect of employment chain, optimizing effect of employment structure, the multiplier effect of employment absorption and the effect of improving the quality of labors and the degree of the intensity of employment and location quotient of employment. Results show that the employment absorption of sugar industry in Chongzuo City is stable and upward slightly, and it shows strong employment effect; the sugar industry in Chongzuo is not only competitive, but also has a great share of market in employment, so it owns strong absorption of employment. The countermeasures for improving the employment level of resource-abundant and industrial cluster in southwest of Guangxi Province are put forward, including elongating industrial chain and widening employment space; strengthening various kinds of formal and informal training to improve the employment capability of laborers; laying stress on industrial structure and optimizing the employment structure; strengthening the construction of the industrial economic zone towards ASEAN(Association of Southeast Asian Nations), and fully displaying the regional advantages of the offshore border.展开更多
2-（2,3-Dihydroxpropyliminomethyl）6-methoxyphenol（H3L）, trimethylacetic acid（Hpiv）, Gd（NO3）3·6 H2O and Co（NO3）2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2（L...2-（2,3-Dihydroxpropyliminomethyl）6-methoxyphenol（H3L）, trimethylacetic acid（Hpiv）, Gd（NO3）3·6 H2O and Co（NO3）2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2（L）2（μ3-OH）2（piv）6]·2 Hpiv·2 CH3OH（1）. X-ray crystallographic analysis reveals that compound 1 was found to be a butterfly heterometallic tetranuclear cluster. The crystal(C64H108Co2Gd2N2O28, Mr = 1785.88) belongs to the triclinic crystal system, space group P1 with a =11.9798（6）, b = 12.0877（5）, c = 15.0367（7） ?, α = 67.320（4）°, β = 81.583（4）°, γ = 75.201（4）°, V =1939.62（18） ?3, Z = 1, T = 293.15 K, R = 0.048 and w R = 0.144 for 16299 observed reflections with I > 2σ（I）. In magnetization study, heterometallic 1 exhibits magnetocaloric effect（MCE） of 14.75 J·kg-1·K-1 at 2 K for ΔH = 5 T, while it does not show non-linear response of the ac-susceptibilities.展开更多
Microclusters from different structures of silicon and carbon are studied by SIMS under UHV conditions in the mass range below M=200. The sputtered mass spectra of ions Sin+, Cn+ and Cn were obtained from the 10 keV O...Microclusters from different structures of silicon and carbon are studied by SIMS under UHV conditions in the mass range below M=200. The sputtered mass spectra of ions Sin+, Cn+ and Cn were obtained from the 10 keV O2+ primary beam bombardment. Comparisons of each spectrum in each group have shown the strong structure effects on the cluster patterns. A brief discussion on the results has been given.展开更多
By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L...By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.展开更多
The vicinage effects are studied for a fast nitrogen diatomic molecular cluster in a high-density plasma target.A variety of plasma parameters are discussed with regard to stopping power ratio,molecular axis deflectio...The vicinage effects are studied for a fast nitrogen diatomic molecular cluster in a high-density plasma target.A variety of plasma parameters are discussed with regard to stopping power ratio,molecular axis deflection and Coulomb explosion.Emphasis is placed on the vicinage effects on Coulomb explosion and stopping power for a nitrogen cluster in plasmas.The results indicate that vicinage effects influence the correlation between ions in the cluster,and the Coulomb explosion will proceed faster with higher projectile speed,lower plasma density and higher plasma temperature.Comparing hydrogen and nitrogen molecular ions for Coulomb explosion and deflection angle under the same set of parameters,one can find that the nitrogen ion has faster Coulomb explosion and stronger deflection of molecular axis due to the contribution of charge.In the initial stage of the Coulomb explosion the stopping power ratio has a higher value due to enhanced vicinage effects while in the later stage the stopping power ratio approaches one,indicating that the vicinage effects disappear and the ions in the cluster simply behave as independent atomic ions in the plasma.展开更多
This study aims to propose a method for quantitatively evaluating the influence which the obstruction of sea breezes by clusters of high-rise buildings has on the urban heat island effect using a weather simulation mo...This study aims to propose a method for quantitatively evaluating the influence which the obstruction of sea breezes by clusters of high-rise buildings has on the urban heat island effect using a weather simulation model and Geographic Information Systems (GIS). Specifically, a method of evaluating the influence of the obstruction of sea breeze by high-rise buildings on the urban heat island effect was proposed. In the method, two scenarios that imagine urban forms which differ with regard to whether or not they contain high-rise buildings are created and weather simulation is conducted, and the results of the simulations are comparatively analyzed focusing on temperature and wind speed. Evaluation was conducted in two stages, and Shiodome of Minato City in the Tokyo Metropolis was selected as the region for evaluation. In two stages of evaluation, a rise in temperature of approximately 0.3 K and a reduction in wind speed of approximately 1 m/s were observed in a region approximately five to ten kilometers square downwind of high-rise buildings in the period 6 PM to 9 PM, and a higher temperature caused by the obstruction of sea breeze by high-rise buildings was identified. The fact that such a higher temperature was confirmed in the time period from 6 PM onwards, in which the temperature decreases, reveals that obstruction of sea breeze by high-rise buildings dulls the decrease in temperature which occurs from evening onwards, and influences nighttime urban heat island formation.展开更多
首先基于2008—2022年中国268个地级市的面板数据,构建超效率SBM-DDF模型系统测度城市碳排放效率;然后采用渐进双重差分法(generalized difference in differences,DID)实证检验国家创新型城市试点政策对碳排放效率的影响效应,在此期间...首先基于2008—2022年中国268个地级市的面板数据,构建超效率SBM-DDF模型系统测度城市碳排放效率;然后采用渐进双重差分法(generalized difference in differences,DID)实证检验国家创新型城市试点政策对碳排放效率的影响效应,在此期间通过安慰剂检验、平行趋势假设检验、工具变量法等多种稳健性方法确保测量结果的可靠性与稳健性;最后从城市群分布、资源禀赋特征以及机器人安装密度等维度开展异质性分析,以揭示政策效应的区域差异,与此同时,研究还构建调节效应模型,探讨人力资本水平、创业活力与产业数字化在政策实施过程中所发挥的内在作用机制。研究结果表明:1)国家创新型城市试点政策显著提升了城市碳排放效率,尤其长三角、成渝和珠三角等城市群,碳排放效率增幅均超过3%,远高于长江中游和京津冀城市群,而在非资源型城市及机器人安装密度较高的城市中,试点政策效果更加显著;2)机制分析显示,试点政策通过提升人力资本质量、激发创业动能和加快产业数字化进程,进一步推动了碳排放效率的持续改善。本研究不仅验证了国家创新型城市试点政策在促进绿色低碳转型中的积极作用,也为推广区域差异化减碳路径与完善创新驱动发展战略提供了有益参考。展开更多
基金supported by the National Basic Research Program of China (2009CB219804)the National Key Technology R&D Program of China (2011BAA04B02)
文摘The aerodynamic behavior of tens of axial flow fans incorporated with air-cooled condensers in a power plant is different from that of an individual fan.Investigation of the aerodynamic characteristics of axial flow fan array benefits its design optimization and running regulation.Based on a representative 2600 MW direct-dry cooling power plant,the flow rate of each fan and the overall flow rate of the fan array are obtained in the absence of ambient wind and at various wind speeds and directions,using CFD simulation.The cluster factor of each fan and the average cluster factor of the fan array are calculated and analyzed.Results show that the cluster factors are different from each other and that the cluster effect with ambient wind is significantly different from the cluster effect with no wind.The fan at the periphery of the array or upwind of the ambient wind generally has a small cluster factor.The average cluster factor of the array decreases with the increasing wind speeds and also varies widely with wind direction.The cluster effect of the axial flow fan array can be applied to optimize the design and operation of air-cooled condensers in a power plant.
基金supported by the major research program from the State Ministry of Science and Technology (No. 2009CB939901)
文摘The geometric and electronic properties of some hydrogenated silicon clusters in the presence of oxygen on the surface have been investigated.The density functional theory with generalized gradient approximation functional was applied in our calculations.By calculating the total energy,the double bond Si=O is shown to be more stable than the bridge bond Si-O-Si for large size oxidized clusters.The results of Mulliken population analysis indicate that a so-called passivation effect is enhanced by oxidization effects.From the energy band structures and density of states,we find that some localized states are induced by the p-orbital of O atom mainly and reduce the energy gaps substantially.
基金Supported by Important Special Research Projects of Guilin University of Electronic Technology (UF09022y)Special Subjects of Guangxi Human Social Science Research Center (XWSKYB2010006)Natural Science Fund of Guangxi Normal University for Nationalities(XYYB2010006)
文摘Taking Chongzuo City of Guangxi Zhuang Autonomous Region as an example, the employment effect of the resource-abundant industrial cluster in southwestern Guangxi Province is analyzed according to the data from the Chongzuo Statistical Yearbook , Guangxi Statistical Yearbook from 2003 to 2008 and the data from the relevant sections of Chongzuo City, and the four employment effects of industrial cluster--the spatial expansion effect of employment chain, optimizing effect of employment structure, the multiplier effect of employment absorption and the effect of improving the quality of labors and the degree of the intensity of employment and location quotient of employment. Results show that the employment absorption of sugar industry in Chongzuo City is stable and upward slightly, and it shows strong employment effect; the sugar industry in Chongzuo is not only competitive, but also has a great share of market in employment, so it owns strong absorption of employment. The countermeasures for improving the employment level of resource-abundant and industrial cluster in southwest of Guangxi Province are put forward, including elongating industrial chain and widening employment space; strengthening various kinds of formal and informal training to improve the employment capability of laborers; laying stress on industrial structure and optimizing the employment structure; strengthening the construction of the industrial economic zone towards ASEAN(Association of Southeast Asian Nations), and fully displaying the regional advantages of the offshore border.
基金supported by the National Natural Science Foundation of China(No.21771043,51572050 and 21601038)Guangxi Natural Science Foundation(No.2015GXNSFDA139007 and 2016GXNSFAA380085)Guangxi Key Laboratory of Electrochemical and Magnetochemical Functional Materials(EMFM20162107)
文摘2-（2,3-Dihydroxpropyliminomethyl）6-methoxyphenol（H3L）, trimethylacetic acid（Hpiv）, Gd（NO3）3·6 H2O and Co（NO3）2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2（L）2（μ3-OH）2（piv）6]·2 Hpiv·2 CH3OH（1）. X-ray crystallographic analysis reveals that compound 1 was found to be a butterfly heterometallic tetranuclear cluster. The crystal(C64H108Co2Gd2N2O28, Mr = 1785.88) belongs to the triclinic crystal system, space group P1 with a =11.9798（6）, b = 12.0877（5）, c = 15.0367（7） ?, α = 67.320（4）°, β = 81.583（4）°, γ = 75.201（4）°, V =1939.62（18） ?3, Z = 1, T = 293.15 K, R = 0.048 and w R = 0.144 for 16299 observed reflections with I > 2σ（I）. In magnetization study, heterometallic 1 exhibits magnetocaloric effect（MCE） of 14.75 J·kg-1·K-1 at 2 K for ΔH = 5 T, while it does not show non-linear response of the ac-susceptibilities.
文摘Microclusters from different structures of silicon and carbon are studied by SIMS under UHV conditions in the mass range below M=200. The sputtered mass spectra of ions Sin+, Cn+ and Cn were obtained from the 10 keV O2+ primary beam bombardment. Comparisons of each spectrum in each group have shown the strong structure effects on the cluster patterns. A brief discussion on the results has been given.
文摘By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.
基金supported by National Natural Science Foundation of China(Nos.11375034,11005025)the Fundamental Research Funds for the Central Universities of China(Nos.3132014231,3132013337)Natural Scientific Research Innovation Foundation in Harbin Institute of Technology,China(HIT.NSRIF.2009044)
文摘The vicinage effects are studied for a fast nitrogen diatomic molecular cluster in a high-density plasma target.A variety of plasma parameters are discussed with regard to stopping power ratio,molecular axis deflection and Coulomb explosion.Emphasis is placed on the vicinage effects on Coulomb explosion and stopping power for a nitrogen cluster in plasmas.The results indicate that vicinage effects influence the correlation between ions in the cluster,and the Coulomb explosion will proceed faster with higher projectile speed,lower plasma density and higher plasma temperature.Comparing hydrogen and nitrogen molecular ions for Coulomb explosion and deflection angle under the same set of parameters,one can find that the nitrogen ion has faster Coulomb explosion and stronger deflection of molecular axis due to the contribution of charge.In the initial stage of the Coulomb explosion the stopping power ratio has a higher value due to enhanced vicinage effects while in the later stage the stopping power ratio approaches one,indicating that the vicinage effects disappear and the ions in the cluster simply behave as independent atomic ions in the plasma.
文摘This study aims to propose a method for quantitatively evaluating the influence which the obstruction of sea breezes by clusters of high-rise buildings has on the urban heat island effect using a weather simulation model and Geographic Information Systems (GIS). Specifically, a method of evaluating the influence of the obstruction of sea breeze by high-rise buildings on the urban heat island effect was proposed. In the method, two scenarios that imagine urban forms which differ with regard to whether or not they contain high-rise buildings are created and weather simulation is conducted, and the results of the simulations are comparatively analyzed focusing on temperature and wind speed. Evaluation was conducted in two stages, and Shiodome of Minato City in the Tokyo Metropolis was selected as the region for evaluation. In two stages of evaluation, a rise in temperature of approximately 0.3 K and a reduction in wind speed of approximately 1 m/s were observed in a region approximately five to ten kilometers square downwind of high-rise buildings in the period 6 PM to 9 PM, and a higher temperature caused by the obstruction of sea breeze by high-rise buildings was identified. The fact that such a higher temperature was confirmed in the time period from 6 PM onwards, in which the temperature decreases, reveals that obstruction of sea breeze by high-rise buildings dulls the decrease in temperature which occurs from evening onwards, and influences nighttime urban heat island formation.
文摘首先基于2008—2022年中国268个地级市的面板数据,构建超效率SBM-DDF模型系统测度城市碳排放效率;然后采用渐进双重差分法(generalized difference in differences,DID)实证检验国家创新型城市试点政策对碳排放效率的影响效应,在此期间通过安慰剂检验、平行趋势假设检验、工具变量法等多种稳健性方法确保测量结果的可靠性与稳健性;最后从城市群分布、资源禀赋特征以及机器人安装密度等维度开展异质性分析,以揭示政策效应的区域差异,与此同时,研究还构建调节效应模型,探讨人力资本水平、创业活力与产业数字化在政策实施过程中所发挥的内在作用机制。研究结果表明:1)国家创新型城市试点政策显著提升了城市碳排放效率,尤其长三角、成渝和珠三角等城市群,碳排放效率增幅均超过3%,远高于长江中游和京津冀城市群,而在非资源型城市及机器人安装密度较高的城市中,试点政策效果更加显著;2)机制分析显示,试点政策通过提升人力资本质量、激发创业动能和加快产业数字化进程,进一步推动了碳排放效率的持续改善。本研究不仅验证了国家创新型城市试点政策在促进绿色低碳转型中的积极作用,也为推广区域差异化减碳路径与完善创新驱动发展战略提供了有益参考。
