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
Nickel-based single-crystal superalloys are the key materials for the manufacturing and development of advanced aeroengines. Rhenium is a crucial alloying element in the advanced nickel-based single-crystal superalloy...Nickel-based single-crystal superalloys are the key materials for the manufacturing and development of advanced aeroengines. Rhenium is a crucial alloying element in the advanced nickel-based single-crystal superalloys for its special strengthening effects. The addition of Re could effectively enhance the creep properties of the single-crystal superalloys; thus, the content of Re is considered as one of the characteristics in different-generation single-crystal superalloys. Owing to the fundamental importance of rhenium to nickel-based single-crystal superalloys, much progress has been made on understanding of the effect of rhenium in the single-crystal superalloys. While the effect of Re doping on the nickelbased superalloys is well documented, the origins of the socalled rhenium effect are still under debate. In this paper,the effect of Re doping on the single-crystal superalloys and progress in understanding the rhenium effect are reviewed. The characteristics of the d-states occupancy in the electronic structure of Re make it the slowest diffusion elements in the single-crystal superalloys, which is undoubtedly responsible for the rhenium effect, while the postulates of Re cluster and the enrichment of Re at the c/c0 interface are still under debate, and the synergistic action of Re with other alloying elements should be further studied.Additionally, the interaction of Re with interfacial dislocations seems to be a promising explanation for the rhenium effect. Finally, the addition of Ru could help suppress topologically close-packed（TCP） phase formation and strengthen the Re doping single-crystal superalloys.Understanding the mechanism of rhenium effect will be beneficial for the effective utilization of Re and the design of low-cost single-crystal superalloys.展开更多
In this paper we discuss neural network-based matrix effect correction in energy dispersive X-ray fluorescence (EDXRF) analysis,with detailed algorithm to classify the samples.The method can correct the matrix effect ...In this paper we discuss neural network-based matrix effect correction in energy dispersive X-ray fluorescence (EDXRF) analysis,with detailed algorithm to classify the samples.The method can correct the matrix effect effectively through classifying the samples automatically,and influence of X-ray absorption and enhancement by major elements of the samples is reduced.Experiments for the complex matrix effect correction in EDXRF analysis of samples in Pangang showed improved accuracy of the elemental analysis result.展开更多
Steel strips are the main of steel products and flatness is an important quality indicator of steel strips. Flatness control is the key and highly difficult technique of strip mills. The bottle-neck restricting the im...Steel strips are the main of steel products and flatness is an important quality indicator of steel strips. Flatness control is the key and highly difficult technique of strip mills. The bottle-neck restricting the improvement of flatness control techniques is that the research on flatness theories and control mathematic models is not in accordance with the requirement of technique developments. To build a simple, rapid and accurate explicit formulation control model has become an urgent need for the development of flatness control technique. This paper puts forward the conception of dynamic effective matrix based on the effective matrix method for flatness control proposed by the authors under the consideration of the influence of the change of parameters in roiling processes on the effective matrix, and the concept is validated by industrial productions. Three methods of the effective matrix generation are induced： the calculation method based on the flatness prediction model; the calculation method based on the data excavation in rolling processes and the direct calculation method based on the network model. A fuzzy neural network effective matrix model is built based on the clusters, and then the network structure is optimized and the high-speed-calculation problem of the dynamic effective matrix is solved. The flatness control scheme for cold strip mills is proposed based on the dynamic effective matrix. On stand 5 of the 1 220 mm five-stand 4-high cold strip tandem mill, the industrial experiment with the control methods of tilting roll and bending roll is done by the control scheme of the static effective matrix and the dynamic effective matrix, respectively. The experiment result proves that the control effect of the dynamic effective matrix is much better than that of the static effective matrix. This paper proposes a new idea and method for the dynamic flatness control in the rolling processes of cold strip mills and develops the theory and model of the flatness control effective matrix method.展开更多
By performing a molecular dynamics simulation, fragmentation of Cu_n clusters scattering from a single-crystal Cu（111） surface is studied. The interactions among copper atoms are modeled by tight-binding potential, ...By performing a molecular dynamics simulation, fragmentation of Cu_n clusters scattering from a single-crystal Cu（111） surface is studied. The interactions among copper atoms are modeled by tight-binding potential, and the positions of the copper clusters at each time step are calculated by integrating the Newton equations of motion. The percentage of unfragmented clusters depends on the incident velocities, angles of incidence, and surface structure. The influence of surface structure on the fragment distribution is discussed, and the clusters appear to be more stable under an axial channeling condition. The fragment distribution shifting toward the small fragment range for cluster scattering along a random direction is confirmed, indicating that the cluster undergoes more intensive fragmentation.展开更多
The stable structures and energies of Ni clusters were investigated using particle swarm optimization(PSO)combined with simulated annealing(SA).Sutton-Chen many-body potential was used in describing the interatomic in...The stable structures and energies of Ni clusters were investigated using particle swarm optimization(PSO)combined with simulated annealing(SA).Sutton-Chen many-body potential was used in describing the interatomic interactions.The simulation results indicate that the structures of Ni clusters are icosahedral-like and binding energy per atom tends to approach that of bulk materials when the atoms number increases.The stability of Ni clusters depends not only on size but also on symmetrical characterization.The structure stability of Nin clusters increases with the increase of total atom number n.It is also found that there exists direct correlation between stability and geometrical structures of the clusters,and relatively higher symmetry clusters are more stable.From the results of the second difference in the binding energy,the clusters at n=3 is more stable than others,and the magic numbers effect is also found.展开更多
Light and heavy clusters are calculated for warm stellar matter in the framework of relativistic mean-field models, in the single-nucleus approximation. The cluster abundances are determined from the minimization of t...Light and heavy clusters are calculated for warm stellar matter in the framework of relativistic mean-field models, in the single-nucleus approximation. The cluster abundances are determined from the minimization of the free energy. In-medium effects of light cluster properties are included by introducing an explicit binding energy shift analytically calculated in the Thomas–Fermi approximation, and the coupling constants are fixed by imposing that the virial limit at low density is recovered. The resulting light cluster abundances come out to be in reasonable agreement with constraints at higher density coming from heavy-ion collision data. Some comparisons with microscopic calculations are also shown.展开更多
The geometric, electronic, and photoabsorption properties of some hydrogenated silicon clusters are investigated. The density functional theory with generalized gradient approximation fimctional is applied. Our study ...The geometric, electronic, and photoabsorption properties of some hydrogenated silicon clusters are investigated. The density functional theory with generalized gradient approximation fimctional is applied. Our study shows that the geometric structures of them relax with their increasing sizes. Synchronously, the polarizations of Si-H bonds become weak slowly but overlap populations increase. In Mulliken population analysis, we find a distinctive passivation effect （some electrons are transferred from outer Si atoms to the central Si with four-coordinate Si atoms）. Owing to the quantum confinement, the energy gap and the lowest excitation energy increase with the decreasing sizes. For nanometer scale cluster, the transition from the highest occupied molecular orbital to the lowest unoccupied molecular orbital state is usually prohibited.展开更多
The traditional Chinese medicine of Radix Hedysari plays an important role in invigorating gas for ascending, benefiting blood for promoting production of fluid, and promoting circulation for removing obstruction in c...The traditional Chinese medicine of Radix Hedysari plays an important role in invigorating gas for ascending, benefiting blood for promoting production of fluid, and promoting circulation for removing obstruction in collaterals, which is consistent with the principle of treatment for osteoporosis. This study is designed to investigate the bioactive components on increasing peak bone mass (PBM) by exploring the spectrum-effect relationship between chromatography fingerprints and effect. Multiple indicators are selected to evaluate the pharmacological activity. In fingerprints, 21 common peaks are obtained, five of which are identified. Furthermore, gray relational analysis (GRA) is a quantitative method of gray system theory and is used to describe the correlation degree of common peaks and pharmacological activities with relational value. 21 components are then divided into three different regions, of which ononin and calycosin play an extremely significant role in increasing PBM. In addition, factor analysis and hierarchical cluster analysis (HCA) are used to screen the optimal producing area for Radix Hedysari. This provides a comprehensive and efficient method to improve the quality evaluation of Radix Hedysari, confirming the bioactive components for PBM-enhancement and further develop its medicinal value.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.
基金financially supported by the National Basic Research Program of China(No.2009CB623701)the National Natural Science Foundation of China(Nos.11374174,50971075 and 51390471)
文摘Nickel-based single-crystal superalloys are the key materials for the manufacturing and development of advanced aeroengines. Rhenium is a crucial alloying element in the advanced nickel-based single-crystal superalloys for its special strengthening effects. The addition of Re could effectively enhance the creep properties of the single-crystal superalloys; thus, the content of Re is considered as one of the characteristics in different-generation single-crystal superalloys. Owing to the fundamental importance of rhenium to nickel-based single-crystal superalloys, much progress has been made on understanding of the effect of rhenium in the single-crystal superalloys. While the effect of Re doping on the nickelbased superalloys is well documented, the origins of the socalled rhenium effect are still under debate. In this paper,the effect of Re doping on the single-crystal superalloys and progress in understanding the rhenium effect are reviewed. The characteristics of the d-states occupancy in the electronic structure of Re make it the slowest diffusion elements in the single-crystal superalloys, which is undoubtedly responsible for the rhenium effect, while the postulates of Re cluster and the enrichment of Re at the c/c0 interface are still under debate, and the synergistic action of Re with other alloying elements should be further studied.Additionally, the interaction of Re with interfacial dislocations seems to be a promising explanation for the rhenium effect. Finally, the addition of Ru could help suppress topologically close-packed（TCP） phase formation and strengthen the Re doping single-crystal superalloys.Understanding the mechanism of rhenium effect will be beneficial for the effective utilization of Re and the design of low-cost single-crystal superalloys.
基金supported by the National Natural Science Foundation of China (No.40574059)the Ministry of Education (No.NCET-04-0904)
文摘In this paper we discuss neural network-based matrix effect correction in energy dispersive X-ray fluorescence (EDXRF) analysis,with detailed algorithm to classify the samples.The method can correct the matrix effect effectively through classifying the samples automatically,and influence of X-ray absorption and enhancement by major elements of the samples is reduced.Experiments for the complex matrix effect correction in EDXRF analysis of samples in Pangang showed improved accuracy of the elemental analysis result.
基金supported by National Natural Science Foundation of China(Grant No. 50675186)Hebei Provincial Major Natural Science Foundation of China (Grant No. E2006001038)
文摘Steel strips are the main of steel products and flatness is an important quality indicator of steel strips. Flatness control is the key and highly difficult technique of strip mills. The bottle-neck restricting the improvement of flatness control techniques is that the research on flatness theories and control mathematic models is not in accordance with the requirement of technique developments. To build a simple, rapid and accurate explicit formulation control model has become an urgent need for the development of flatness control technique. This paper puts forward the conception of dynamic effective matrix based on the effective matrix method for flatness control proposed by the authors under the consideration of the influence of the change of parameters in roiling processes on the effective matrix, and the concept is validated by industrial productions. Three methods of the effective matrix generation are induced： the calculation method based on the flatness prediction model; the calculation method based on the data excavation in rolling processes and the direct calculation method based on the network model. A fuzzy neural network effective matrix model is built based on the clusters, and then the network structure is optimized and the high-speed-calculation problem of the dynamic effective matrix is solved. The flatness control scheme for cold strip mills is proposed based on the dynamic effective matrix. On stand 5 of the 1 220 mm five-stand 4-high cold strip tandem mill, the industrial experiment with the control methods of tilting roll and bending roll is done by the control scheme of the static effective matrix and the dynamic effective matrix, respectively. The experiment result proves that the control effect of the dynamic effective matrix is much better than that of the static effective matrix. This paper proposes a new idea and method for the dynamic flatness control in the rolling processes of cold strip mills and develops the theory and model of the flatness control effective matrix method.
基金Project supported by the National Natural Science Foundation of China(Grant No.11405166)
文摘By performing a molecular dynamics simulation, fragmentation of Cu_n clusters scattering from a single-crystal Cu（111） surface is studied. The interactions among copper atoms are modeled by tight-binding potential, and the positions of the copper clusters at each time step are calculated by integrating the Newton equations of motion. The percentage of unfragmented clusters depends on the incident velocities, angles of incidence, and surface structure. The influence of surface structure on the fragment distribution is discussed, and the clusters appear to be more stable under an axial channeling condition. The fragment distribution shifting toward the small fragment range for cluster scattering along a random direction is confirmed, indicating that the cluster undergoes more intensive fragmentation.
基金Project(60371046)supported by the National Natural Science Foundation of China
文摘The stable structures and energies of Ni clusters were investigated using particle swarm optimization(PSO)combined with simulated annealing(SA).Sutton-Chen many-body potential was used in describing the interatomic interactions.The simulation results indicate that the structures of Ni clusters are icosahedral-like and binding energy per atom tends to approach that of bulk materials when the atoms number increases.The stability of Ni clusters depends not only on size but also on symmetrical characterization.The structure stability of Nin clusters increases with the increase of total atom number n.It is also found that there exists direct correlation between stability and geometrical structures of the clusters,and relatively higher symmetry clusters are more stable.From the results of the second difference in the binding energy,the clusters at n=3 is more stable than others,and the magic numbers effect is also found.
基金partly supported by the FCT(Portugal)Project No.UID/FIS/04564/2016by former NewCompStar,COST Action MP1304.H.P.is supported by FCT(Portugal)under Project No.SFRH/BPD/95566/2013the Organizers of IWND 2018 for the opportunity to present this work,as well as the financial support received
文摘Light and heavy clusters are calculated for warm stellar matter in the framework of relativistic mean-field models, in the single-nucleus approximation. The cluster abundances are determined from the minimization of the free energy. In-medium effects of light cluster properties are included by introducing an explicit binding energy shift analytically calculated in the Thomas–Fermi approximation, and the coupling constants are fixed by imposing that the virial limit at low density is recovered. The resulting light cluster abundances come out to be in reasonable agreement with constraints at higher density coming from heavy-ion collision data. Some comparisons with microscopic calculations are also shown.
基金supported by the Hebei North University Foundation (No.200706)
文摘The geometric, electronic, and photoabsorption properties of some hydrogenated silicon clusters are investigated. The density functional theory with generalized gradient approximation fimctional is applied. Our study shows that the geometric structures of them relax with their increasing sizes. Synchronously, the polarizations of Si-H bonds become weak slowly but overlap populations increase. In Mulliken population analysis, we find a distinctive passivation effect （some electrons are transferred from outer Si atoms to the central Si with four-coordinate Si atoms）. Owing to the quantum confinement, the energy gap and the lowest excitation energy increase with the decreasing sizes. For nanometer scale cluster, the transition from the highest occupied molecular orbital to the lowest unoccupied molecular orbital state is usually prohibited.
基金supported by the National Natural Science Funds of China(Grant No.81703664)Science and Technology Funds of Lanzhou,China(Grant No.201603111)
文摘The traditional Chinese medicine of Radix Hedysari plays an important role in invigorating gas for ascending, benefiting blood for promoting production of fluid, and promoting circulation for removing obstruction in collaterals, which is consistent with the principle of treatment for osteoporosis. This study is designed to investigate the bioactive components on increasing peak bone mass (PBM) by exploring the spectrum-effect relationship between chromatography fingerprints and effect. Multiple indicators are selected to evaluate the pharmacological activity. In fingerprints, 21 common peaks are obtained, five of which are identified. Furthermore, gray relational analysis (GRA) is a quantitative method of gray system theory and is used to describe the correlation degree of common peaks and pharmacological activities with relational value. 21 components are then divided into three different regions, of which ononin and calycosin play an extremely significant role in increasing PBM. In addition, factor analysis and hierarchical cluster analysis (HCA) are used to screen the optimal producing area for Radix Hedysari. This provides a comprehensive and efficient method to improve the quality evaluation of Radix Hedysari, confirming the bioactive components for PBM-enhancement and further develop its medicinal value.
