We review the predictions of quark models for multiquark configurations that are bound or resonant states,and compare different methods for estimating the properties of resonances.
Geometrical configurations play a crucial role in dual-atom catalysts(DACs)for electrocatalytic applications.Significant progress has been made to design DACs electrocatalysts with various geometri-cal configurations,...Geometrical configurations play a crucial role in dual-atom catalysts(DACs)for electrocatalytic applications.Significant progress has been made to design DACs electrocatalysts with various geometri-cal configurations,but in-depth understanding the relationship between geometrical configurations and metal-metal interaction mechanisms for designing targeted DACs is still required.In this review,the recent progress in engineering of geometrical configurations of DACs is systematically summarized.Based on the polarity of geometrical configuration,DACs can be classified into two different types that are homonuclear and heteronuclear DACs.Furthermore,with regard to the geometrical configurations of the active sites,homonuclear DACs are identified into adjacent and bridged configurations,and heteronuclear DACs can be classified into adjacent,bridged,and separated configurations.Subsequently,metal-metal interactions in DACs with different geometrical configurations are introduced.Additionally,the applications of DACs in different electrocatalytic reactions are discussed,including the oxygen reduction reaction(ORR),oxygen evolution reaction(OER),hydrogen evolution reaction(HER),and other catalysis.Finally,the future challenges and perspectives for advancements in DACs are high-lighted.This review aims to provide inspiration for the design of highly effcient DACs towards energy relatedapplications.展开更多
Field reversed configuration(FRC)is widely considered as an ideal target plasma for magnetoinertial fusion.However,its confinement and stability,both proportional to the radius,will deteriorate inevitably during radia...Field reversed configuration(FRC)is widely considered as an ideal target plasma for magnetoinertial fusion.However,its confinement and stability,both proportional to the radius,will deteriorate inevitably during radial compression.Hence,we propose a new fusion approach based on axial compression of a large-sized FRC.The axial compression can be made by plasma jets or plasmoids converging onto the axial ends of the FRC.The parameter space that can reach the ignition condition while preserving the FRC's overall quality is studied using a numerical model based on different FRC confinement scalings.It is found that ignition is possible for a large FRC that can be achieved with the current FRC formation techniques if compression ratio is greater than 50.A more realistic compression is to combine axial with moderate radial compression,which is also presented and calculated in this work.展开更多
Fixed-bed reactors are generally considered the optimal choice for numerous multi-phase catalytic reactions due to their excellent performance and stability.However,conventional fixed beds often encounter challenges r...Fixed-bed reactors are generally considered the optimal choice for numerous multi-phase catalytic reactions due to their excellent performance and stability.However,conventional fixed beds often encounter challenges related to inadequate mass transfer and a high pressure drop caused by the non-uniform void fraction distribution.To enhance the overall performance of fixed beds,the impact of different packing configurations on performance was investigated.Experimental and simulation methods were used to investigate the fluid flow and mass transfer performances of various packed beds under different flow rates.It was found that structured beds exhibited a significantly lower pressure drop per unit length than conventional packed beds.Furthermore,the packing configurations had a critical role in improving the overall performance of fixed beds.Specifically,structured packed beds,particularly the H-2 packing configuration,effectively reduced the pressure drop per unit length and improved the mass transfer efficiency.The H-2 packing configuration consisted of two parallel strips of particles in each layer,with strips arranged perpendicularly between adjacent layers,and the spacing between the strips varied from layer to layer.展开更多
The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe distance.To guarantee collision avoidance,the safety distance should be calcula...The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe distance.To guarantee collision avoidance,the safety distance should be calculated using the state-of-the-art space-time separation principle that separates the Emergency Braking(EB)trajectories of two successive units during the whole EB process.In this case,the minimal safety distance is usually numerically calculated without an analytic formulation.Thus,the constrained VCTS control problem is hard to address with space-time separation,which is still a gap in the existing literature.To solve this problem,we propose a Distributed Economic Model Predictive Control(DEMPC)approach with computation efficiency and theoretical guarantee.Specifically,to alleviate the computation burden,we transform implicit safety constraints into explicitly linear ones,such that the optimal control problem in DEMPC is a quadratic programming problem that can be solved efficiently.For theoretical analysis,sufficient conditions are derived to guarantee the recursive feasibility and stability of DEMPC,employing compatibility constraints,tube techniques and terminal ingredient tuning.Moreover,we extend our approach with globally optimal and distributed online EB configuration methods to shorten the minimal distance among VCTS.Finally,experimental results demonstrate the performance and advantages of the proposed approaches.展开更多
At evaluating the combat effectiveness of the defense system, target′s probability to penetrate the defended area is a primary care taking index. In this paper, stochastic model to compete the probability that targe...At evaluating the combat effectiveness of the defense system, target′s probability to penetrate the defended area is a primary care taking index. In this paper, stochastic model to compete the probability that target penetrates the defended area along any flight path is established by the state analysis and statistical equilibrium analysis of stochastic service system theory. The simulated annealing algorithm is an enlightening random search method based on Monte Carlo recursion, and it can find global optimal solution by simulating annealing process. Combining stochastic model to compete the probability and simulated annealing algorithm, this paper establishes the method to solve problem quantitatively about combat configuration optimization of weapon systems. The calculated result shows that the perfect configuration for fire cells of the weapon is fast found by using this method, and this quantificational method for combat configuration is faster and more scientific than previous one based on principle via map fire field.展开更多
Aim To obtain an optimizing range of the main configuration parameters of double swirls combustion system (DSCS) Methods To analyze the influence of DS combustion cham-ber configuration parameters on fuel spray and mi...Aim To obtain an optimizing range of the main configuration parameters of double swirls combustion system (DSCS) Methods To analyze the influence of DS combustion cham-ber configuration parameters on fuel spray and mixing by means of the fuel jet developmentperiphery charts obtained by the high speed photography with a modeling test device deve-loped by authors,and to examine it by the tests on a single cylinder diesel engine.Resultsand Conclusion The mixing process can be divided into four phases.The optimizing range of the ration of the inner chamber diameter to the cylinder bore,d2/D,is 0.4-0.7; and the outerchamber diameter,d1 the height of the circular ridge to the piston top face,h1,the radius of outer/inner chamber circle,R1,R2 ,the max depth of outer/inner chamber bowl,H1,H2,etc. are also important展开更多
A mechanics system consisting of three mass points on sphere S 2 is considered. The configuration space of the system is a fibre bundle over S 2 . It is proved that first Chern class of the bundle is -2 c 1...A mechanics system consisting of three mass points on sphere S 2 is considered. The configuration space of the system is a fibre bundle over S 2 . It is proved that first Chern class of the bundle is -2 c 1(γ) where γ is the canonical line bundle over the complex projective space CP 1=S 2 , which shows the bundle is non trivial. The information about the first Chern class makes the cohomology groups and homotopy groups of the configuration space worked out. In addition the effects of these topolo gical properties of the configuration space on the behavior in large scale of the system, as the number of equilibrium positions, periodic orbits and reduced phase space, are discussed.展开更多
Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteri...Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteristics of the metal plasma which consists of metal ions coming from cathode and generated by vacuum discharge. In this research, the generation characteristics of the metal plasma generated by vacuum discharge are discussed for four patterns of electrode configurations, i.e. cone-mesh electrode setup, cone-cross line electrode setup, cone-line electrode setup and cone-ring electrode setup. Characteristics of the metal plasma, such as elec- tron density, electron temperature, space potential, ion energy, are measured by the probe method for discussing the impacts of different electrode configurations on the density of generated metal plasma. Moreover, the diffusion velocities of the metal plasma are measured for cathode materials of Pb, Al, and Cu, respectively. The experimental results indicate that the plasma generated by the discharge of cone-ring electrode configuration possesses the maximum density and the metal plasma generated by the Al cathode possesses the fastest diffusion velocity and the highest kinetic energy.展开更多
The Fusion-Driven Subcritical System(FDS)is a subcritical nuclear energy systemdrived by fusion neutron source.In this paper,an advanced plasma configuration for FDS systemhas been proposed,which aims at high beta,hig...The Fusion-Driven Subcritical System(FDS)is a subcritical nuclear energy systemdrived by fusion neutron source.In this paper,an advanced plasma configuration for FDS systemhas been proposed,which aims at high beta,high bootstrap current and good confinement.Afixed-boundary equilibrium code has been used to obtain ideal equilibrium configuration.In order展开更多
Streamline box girders are widely applied in the design and construction of long-span bridges all over the world. In order to study the influence of modifications of aerodynamic configuration and accessory components ...Streamline box girders are widely applied in the design and construction of long-span bridges all over the world. In order to study the influence of modifications of aerodynamic configuration and accessory components on flutter and vortex-induced vibration （VIV）, more than 60 cases were tested through a 1：50 scale section model. The test results indicates that the aerodynamic configuration and accessory components of streamline box girders can signifi- cantly affect the wind-induced vibration of bridge, which is in good agreement with the experience of past researchers. From the tests carried out, it is observed that if the horizontal angle of the inclined web of the streamline box girder is below 16°, the critical flutter wind speed of bridge will increase remarkably, and the VIV will diminish. The test results also show that the 15° inclined web can restrain the formation of vortex near the tail, and consequently improve the performance of aerodynamic stability of long-span bridges. Finally, a new streamline box girder with 15° inclined web was presented and strongly recommended in the aerodynamic configuration design of long-span bridges.展开更多
Experimental investigations into the effects of the magnetic field configuration near the channel exit on the plume of Hall thrusters were conducted. The magnetic field configuration near the channel exit is character...Experimental investigations into the effects of the magnetic field configuration near the channel exit on the plume of Hall thrusters were conducted. The magnetic field configuration near the channel exit is characterized by the inclination angle between the magnetic field lines and the thruster radial direction. Different inclination angles were obtained by varying the current ratio in the coils. The plume divergence angles were measured by a dual-directed probe. The results showed that the plume divergence angle increased obviously with the increase in the magnitude of the inclination angle near the channel exit. Therefore, in order to optimize the magnetic field for reducing plume divergence, the magnitude of the inclination angle should be reduced as much as possible. It suggests that the magnetic field configuration near the channel exit is another important factor that affects plume divergence.展开更多
A series of experimental results of field-reversed configurations(FRCs) on a KMAX(Keda Mirror with AXisymmetricity) tandem mirror machine are reported.Single-side FRC translation processes with three different gas spe...A series of experimental results of field-reversed configurations(FRCs) on a KMAX(Keda Mirror with AXisymmetricity) tandem mirror machine are reported.Single-side FRC translation processes with three different gas species were measured by avalanche photodiodes.Consistent with the theoretical prediction, the measured FRC speeds were inversely proportional to the square root of the ion mass.However, the speeds of the hydrogen FRC increased even in a uniform magnetic field region while the speeds of the helium and argon FRCs decreased.Possible mechanisms are discussed.The speed of the second pass due to the reflection of the mirror fields was found to be ~1/3 of the first pass speed.The internal magnetic fields were measured for a colliding-merging argon FRC, and the results show that, even for very slowmoving FRCs, merging can occur.展开更多
The Helimak of USA is a plasma physics experimental device designed and built by CASIPP. Its configuration of magnetic field is of very importance during the operation of this device. In this paper, the influence of m...The Helimak of USA is a plasma physics experimental device designed and built by CASIPP. Its configuration of magnetic field is of very importance during the operation of this device. In this paper, the influence of magnetic permeability on configuration of magnetic field will be discussed due to the effect of weld metal in the vacuum vessel of Helimak, and some conclusion is useful for some engineering designs of the fusion experimental device.展开更多
ARINC653 systems, which have been widely used in avionics industry, are an important class of safety-critical applications. Partitions are the core concept in the Arinc653 system architecture. Due to the existence of ...ARINC653 systems, which have been widely used in avionics industry, are an important class of safety-critical applications. Partitions are the core concept in the Arinc653 system architecture. Due to the existence of partitions, the system designer must allocate adequate time slots statically to each partition in the design phase. Although some time slot allocation policies could be borrowed from task scheduling policies, no existing literatures give an optimal allocation policy. In this paper, we present a partition configuration policy and prove that this policy is optimal in the sense that if this policy fails to configure adequate time slots to each partition, nor do other policies. Then, by simulation, we show the effects of different partition configuration policies on time slot allocation of partitions and task response time, respectively.展开更多
An analytic configuration interaction method based on variationally optimized internally orthogonalized modified Laguerre orbitals is presented. We have developed the corresponding computer code. For application, we s...An analytic configuration interaction method based on variationally optimized internally orthogonalized modified Laguerre orbitals is presented. We have developed the corresponding computer code. For application, we study the 1s2s ^1S isoelectronic sequence from helium to neon, and compare with other methods. By taking into account the Eekart upper-bound theorem, we obtained more accurate and more intuitively understandable results than Hartree-Fock and multi-configuration Hartree-Fock reported results.展开更多
Configurational information entropy(CIE)theory was employed to determine the neutron-skin thickness of neutron-rich calcium isotopes.The nuclear density distributions and fragment cross sections in 350 MeV/u ^(40-60)C...Configurational information entropy(CIE)theory was employed to determine the neutron-skin thickness of neutron-rich calcium isotopes.The nuclear density distributions and fragment cross sections in 350 MeV/u ^(40-60)Ca+^(9)Be projectile fragmentation reactions were calculated using a modified statistical abrasion-ablation model.CIE quantities were determined from the nuclear density,isotopic,mass,and charge distributions.The linear correlations between the CIE determined using the isotopic,mass,and charge distributions and the neutron-skin thickness of the projectile nucleus show that CIE provides new methods to extract the neutron-skin thickness of neutron-rich nuclei.展开更多
Developing the highly active, cost-effective, environmental-friendly, and ultra-stable nonprecious electrocatalysts for hydrogen evolution reaction(HER) is distinctly indispensable for the large-scale practical applic...Developing the highly active, cost-effective, environmental-friendly, and ultra-stable nonprecious electrocatalysts for hydrogen evolution reaction(HER) is distinctly indispensable for the large-scale practical applications of hydrolytic hydrogen production. Herein, we report the synthesis of well-integrated electrode, NiV layered double hydroxide nanosheet array grown in-situ on porous nickel foam(abbreviated as in-NiV-LDH/NF) via the facile one-step hydrothermal route. Interestingly, the valence configuration of vanadium(V) sites in such NiV-LDH are well dominated by the innovative use of NF as the reducing regulator, achieving the reassembled in-NiV-LDH/NF with a high proportion of trivalent V ions(V3+), and then an enhanced intrinsic electrocatalytic HER activity. The HER testing results show that the in-NiVLDH/NF drives the current densities of 10 and 100 mA cm-2 at extremely low overpotentials of 114 and 245 mV without iR-compensation respectively, even outperforms commercial 20 wt% Pt/C at the large current density of over 80 mA cm-2 in alkaline media, as well as gives robust catalytic durability of at least 100 h in both alkaline and neutral media. More importantly, this work provides a fresh perspective for designing bimetal(oxy) hydroxides electrocatalysts with efficient hydrogen generation.展开更多
Spatial distributions of plasma parameters such as electron density, electron temperature and electric potential were investigated using a commercial simulation software （COMSOLTM） to predict the effects of antenna ...Spatial distributions of plasma parameters such as electron density, electron temperature and electric potential were investigated using a commercial simulation software （COMSOLTM） to predict the effects of antenna configuration in a large area inductively cou- pled plasma （ICP） system for flat panel displays. Nine planar antenna sets were evenly placed above a ceramic window. While the electron density was influenced by both the input current and gas pressure, the electron temperature and electric potential were dominantly affected by the gas pressure.展开更多
Single- and double-null divertor configurations in HL-2A are simulated by SWEQU equilibrium code. Lower divertor discharges in the first physics campaign have been achieved by two kinds of power supply method of multi...Single- and double-null divertor configurations in HL-2A are simulated by SWEQU equilibrium code. Lower divertor discharges in the first physics campaign have been achieved by two kinds of power supply method of multipole-field coils. Single-null divertor configuration has been identified by visible photography, target probe arrays and the reconstructed magnetic surface. Magnetic separatrix and minor radius of plasma column are obtained by a reconstructed code of multiple current filaments using 18 Mirnov signals.展开更多
文摘We review the predictions of quark models for multiquark configurations that are bound or resonant states,and compare different methods for estimating the properties of resonances.
基金supported by the Natural Science Foundation of China (22179062,52125202,and U2004209)the Natural Science Foundation of Jiangsu Province (BK20230035)+1 种基金the Fundamental Research Funds for the Central Universities (30922010303)the Intergovernmental Cooperation Projects in the National Key Research and Development Plan of the Ministry of Science and Technology of PRC (2022YFE0196800)
文摘Geometrical configurations play a crucial role in dual-atom catalysts(DACs)for electrocatalytic applications.Significant progress has been made to design DACs electrocatalysts with various geometri-cal configurations,but in-depth understanding the relationship between geometrical configurations and metal-metal interaction mechanisms for designing targeted DACs is still required.In this review,the recent progress in engineering of geometrical configurations of DACs is systematically summarized.Based on the polarity of geometrical configuration,DACs can be classified into two different types that are homonuclear and heteronuclear DACs.Furthermore,with regard to the geometrical configurations of the active sites,homonuclear DACs are identified into adjacent and bridged configurations,and heteronuclear DACs can be classified into adjacent,bridged,and separated configurations.Subsequently,metal-metal interactions in DACs with different geometrical configurations are introduced.Additionally,the applications of DACs in different electrocatalytic reactions are discussed,including the oxygen reduction reaction(ORR),oxygen evolution reaction(OER),hydrogen evolution reaction(HER),and other catalysis.Finally,the future challenges and perspectives for advancements in DACs are high-lighted.This review aims to provide inspiration for the design of highly effcient DACs towards energy relatedapplications.
基金supported by National Natural Science Foundation of China(No.12175226)。
文摘Field reversed configuration(FRC)is widely considered as an ideal target plasma for magnetoinertial fusion.However,its confinement and stability,both proportional to the radius,will deteriorate inevitably during radial compression.Hence,we propose a new fusion approach based on axial compression of a large-sized FRC.The axial compression can be made by plasma jets or plasmoids converging onto the axial ends of the FRC.The parameter space that can reach the ignition condition while preserving the FRC's overall quality is studied using a numerical model based on different FRC confinement scalings.It is found that ignition is possible for a large FRC that can be achieved with the current FRC formation techniques if compression ratio is greater than 50.A more realistic compression is to combine axial with moderate radial compression,which is also presented and calculated in this work.
文摘Fixed-bed reactors are generally considered the optimal choice for numerous multi-phase catalytic reactions due to their excellent performance and stability.However,conventional fixed beds often encounter challenges related to inadequate mass transfer and a high pressure drop caused by the non-uniform void fraction distribution.To enhance the overall performance of fixed beds,the impact of different packing configurations on performance was investigated.Experimental and simulation methods were used to investigate the fluid flow and mass transfer performances of various packed beds under different flow rates.It was found that structured beds exhibited a significantly lower pressure drop per unit length than conventional packed beds.Furthermore,the packing configurations had a critical role in improving the overall performance of fixed beds.Specifically,structured packed beds,particularly the H-2 packing configuration,effectively reduced the pressure drop per unit length and improved the mass transfer efficiency.The H-2 packing configuration consisted of two parallel strips of particles in each layer,with strips arranged perpendicularly between adjacent layers,and the spacing between the strips varied from layer to layer.
基金supported by the National Natural Science Foundation of China(52372310)the State Key Laboratory of Advanced Rail Autonomous Operation(RAO2023ZZ001)+1 种基金the Fundamental Research Funds for the Central Universities(2022JBQY001)Beijing Laboratory of Urban Rail Transit.
文摘The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe distance.To guarantee collision avoidance,the safety distance should be calculated using the state-of-the-art space-time separation principle that separates the Emergency Braking(EB)trajectories of two successive units during the whole EB process.In this case,the minimal safety distance is usually numerically calculated without an analytic formulation.Thus,the constrained VCTS control problem is hard to address with space-time separation,which is still a gap in the existing literature.To solve this problem,we propose a Distributed Economic Model Predictive Control(DEMPC)approach with computation efficiency and theoretical guarantee.Specifically,to alleviate the computation burden,we transform implicit safety constraints into explicitly linear ones,such that the optimal control problem in DEMPC is a quadratic programming problem that can be solved efficiently.For theoretical analysis,sufficient conditions are derived to guarantee the recursive feasibility and stability of DEMPC,employing compatibility constraints,tube techniques and terminal ingredient tuning.Moreover,we extend our approach with globally optimal and distributed online EB configuration methods to shorten the minimal distance among VCTS.Finally,experimental results demonstrate the performance and advantages of the proposed approaches.
文摘At evaluating the combat effectiveness of the defense system, target′s probability to penetrate the defended area is a primary care taking index. In this paper, stochastic model to compete the probability that target penetrates the defended area along any flight path is established by the state analysis and statistical equilibrium analysis of stochastic service system theory. The simulated annealing algorithm is an enlightening random search method based on Monte Carlo recursion, and it can find global optimal solution by simulating annealing process. Combining stochastic model to compete the probability and simulated annealing algorithm, this paper establishes the method to solve problem quantitatively about combat configuration optimization of weapon systems. The calculated result shows that the perfect configuration for fire cells of the weapon is fast found by using this method, and this quantificational method for combat configuration is faster and more scientific than previous one based on principle via map fire field.
文摘Aim To obtain an optimizing range of the main configuration parameters of double swirls combustion system (DSCS) Methods To analyze the influence of DS combustion cham-ber configuration parameters on fuel spray and mixing by means of the fuel jet developmentperiphery charts obtained by the high speed photography with a modeling test device deve-loped by authors,and to examine it by the tests on a single cylinder diesel engine.Resultsand Conclusion The mixing process can be divided into four phases.The optimizing range of the ration of the inner chamber diameter to the cylinder bore,d2/D,is 0.4-0.7; and the outerchamber diameter,d1 the height of the circular ridge to the piston top face,h1,the radius of outer/inner chamber circle,R1,R2 ,the max depth of outer/inner chamber bowl,H1,H2,etc. are also important
文摘A mechanics system consisting of three mass points on sphere S 2 is considered. The configuration space of the system is a fibre bundle over S 2 . It is proved that first Chern class of the bundle is -2 c 1(γ) where γ is the canonical line bundle over the complex projective space CP 1=S 2 , which shows the bundle is non trivial. The information about the first Chern class makes the cohomology groups and homotopy groups of the configuration space worked out. In addition the effects of these topolo gical properties of the configuration space on the behavior in large scale of the system, as the number of equilibrium positions, periodic orbits and reduced phase space, are discussed.
文摘Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteristics of the metal plasma which consists of metal ions coming from cathode and generated by vacuum discharge. In this research, the generation characteristics of the metal plasma generated by vacuum discharge are discussed for four patterns of electrode configurations, i.e. cone-mesh electrode setup, cone-cross line electrode setup, cone-line electrode setup and cone-ring electrode setup. Characteristics of the metal plasma, such as elec- tron density, electron temperature, space potential, ion energy, are measured by the probe method for discussing the impacts of different electrode configurations on the density of generated metal plasma. Moreover, the diffusion velocities of the metal plasma are measured for cathode materials of Pb, Al, and Cu, respectively. The experimental results indicate that the plasma generated by the discharge of cone-ring electrode configuration possesses the maximum density and the metal plasma generated by the Al cathode possesses the fastest diffusion velocity and the highest kinetic energy.
基金National Sciences Foundation of China(No.10175068)
文摘The Fusion-Driven Subcritical System(FDS)is a subcritical nuclear energy systemdrived by fusion neutron source.In this paper,an advanced plasma configuration for FDS systemhas been proposed,which aims at high beta,high bootstrap current and good confinement.Afixed-boundary equilibrium code has been used to obtain ideal equilibrium configuration.In order
文摘Streamline box girders are widely applied in the design and construction of long-span bridges all over the world. In order to study the influence of modifications of aerodynamic configuration and accessory components on flutter and vortex-induced vibration （VIV）, more than 60 cases were tested through a 1：50 scale section model. The test results indicates that the aerodynamic configuration and accessory components of streamline box girders can signifi- cantly affect the wind-induced vibration of bridge, which is in good agreement with the experience of past researchers. From the tests carried out, it is observed that if the horizontal angle of the inclined web of the streamline box girder is below 16°, the critical flutter wind speed of bridge will increase remarkably, and the VIV will diminish. The test results also show that the 15° inclined web can restrain the formation of vortex near the tail, and consequently improve the performance of aerodynamic stability of long-span bridges. Finally, a new streamline box girder with 15° inclined web was presented and strongly recommended in the aerodynamic configuration design of long-span bridges.
基金supported by National Natural Science Foundation of China(No.50676026)the Program for Chair Professors of"Cheung Kong Scholars Program"of China in 2008
文摘Experimental investigations into the effects of the magnetic field configuration near the channel exit on the plume of Hall thrusters were conducted. The magnetic field configuration near the channel exit is characterized by the inclination angle between the magnetic field lines and the thruster radial direction. Different inclination angles were obtained by varying the current ratio in the coils. The plume divergence angles were measured by a dual-directed probe. The results showed that the plume divergence angle increased obviously with the increase in the magnitude of the inclination angle near the channel exit. Therefore, in order to optimize the magnetic field for reducing plume divergence, the magnitude of the inclination angle should be reduced as much as possible. It suggests that the magnetic field configuration near the channel exit is another important factor that affects plume divergence.
基金supported by the National Key R&D Program of China (Nos.2017YFA0402500 and 2017YFE0301802)National Natural Science Foundation (No.11475172)the Key Research Program of Frontier Sciences, CAS (No.QYZDJ-SSW-DQC010)
文摘A series of experimental results of field-reversed configurations(FRCs) on a KMAX(Keda Mirror with AXisymmetricity) tandem mirror machine are reported.Single-side FRC translation processes with three different gas species were measured by avalanche photodiodes.Consistent with the theoretical prediction, the measured FRC speeds were inversely proportional to the square root of the ion mass.However, the speeds of the hydrogen FRC increased even in a uniform magnetic field region while the speeds of the helium and argon FRCs decreased.Possible mechanisms are discussed.The speed of the second pass due to the reflection of the mirror fields was found to be ~1/3 of the first pass speed.The internal magnetic fields were measured for a colliding-merging argon FRC, and the results show that, even for very slowmoving FRCs, merging can occur.
文摘The Helimak of USA is a plasma physics experimental device designed and built by CASIPP. Its configuration of magnetic field is of very importance during the operation of this device. In this paper, the influence of magnetic permeability on configuration of magnetic field will be discussed due to the effect of weld metal in the vacuum vessel of Helimak, and some conclusion is useful for some engineering designs of the fusion experimental device.
基金supported by the National Natural Science Foundation of China under Grant No. 90718019the National High-Tech Research and Development Plan of China under Grant No. 2007AA010304
文摘ARINC653 systems, which have been widely used in avionics industry, are an important class of safety-critical applications. Partitions are the core concept in the Arinc653 system architecture. Due to the existence of partitions, the system designer must allocate adequate time slots statically to each partition in the design phase. Although some time slot allocation policies could be borrowed from task scheduling policies, no existing literatures give an optimal allocation policy. In this paper, we present a partition configuration policy and prove that this policy is optimal in the sense that if this policy fails to configure adequate time slots to each partition, nor do other policies. Then, by simulation, we show the effects of different partition configuration policies on time slot allocation of partitions and task response time, respectively.
基金Project supported by the National Natural Science Foundation of China （Grant No 10347126）. Acknowledgements Xiong Zhuang acknowledges the Greek State Scholarship Foundation （I.K.Y.） and the National Hellenic Research Foundation Scholarship that partially supported this work.
文摘An analytic configuration interaction method based on variationally optimized internally orthogonalized modified Laguerre orbitals is presented. We have developed the corresponding computer code. For application, we study the 1s2s ^1S isoelectronic sequence from helium to neon, and compare with other methods. By taking into account the Eekart upper-bound theorem, we obtained more accurate and more intuitively understandable results than Hartree-Fock and multi-configuration Hartree-Fock reported results.
基金supported by the National Natural Science Foundation of China(Nos.11975091 and U1732135)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province,China(No.21IRTSTHN011)。
文摘Configurational information entropy(CIE)theory was employed to determine the neutron-skin thickness of neutron-rich calcium isotopes.The nuclear density distributions and fragment cross sections in 350 MeV/u ^(40-60)Ca+^(9)Be projectile fragmentation reactions were calculated using a modified statistical abrasion-ablation model.CIE quantities were determined from the nuclear density,isotopic,mass,and charge distributions.The linear correlations between the CIE determined using the isotopic,mass,and charge distributions and the neutron-skin thickness of the projectile nucleus show that CIE provides new methods to extract the neutron-skin thickness of neutron-rich nuclei.
基金supported by the National Natural Science Foundation of China (Nos.21701107, 51672165)Natural Science Foundation of Shaanxi Province (2019JQ-018)+3 种基金Doctoral Scientific Research Startup Foundation of Shaanxi University of Science and Technology (2016QNBT-07)Platform construction Fund for Imported talent of Shaanxi University of Science and Technology (134080038)National Key R&D Program of China (2017YFB0308300)Xi’an Key Laboratory of Green Manufacture of Ceramic materials Foundation (2019220214SYS017CG039)。
文摘Developing the highly active, cost-effective, environmental-friendly, and ultra-stable nonprecious electrocatalysts for hydrogen evolution reaction(HER) is distinctly indispensable for the large-scale practical applications of hydrolytic hydrogen production. Herein, we report the synthesis of well-integrated electrode, NiV layered double hydroxide nanosheet array grown in-situ on porous nickel foam(abbreviated as in-NiV-LDH/NF) via the facile one-step hydrothermal route. Interestingly, the valence configuration of vanadium(V) sites in such NiV-LDH are well dominated by the innovative use of NF as the reducing regulator, achieving the reassembled in-NiV-LDH/NF with a high proportion of trivalent V ions(V3+), and then an enhanced intrinsic electrocatalytic HER activity. The HER testing results show that the in-NiVLDH/NF drives the current densities of 10 and 100 mA cm-2 at extremely low overpotentials of 114 and 245 mV without iR-compensation respectively, even outperforms commercial 20 wt% Pt/C at the large current density of over 80 mA cm-2 in alkaline media, as well as gives robust catalytic durability of at least 100 h in both alkaline and neutral media. More importantly, this work provides a fresh perspective for designing bimetal(oxy) hydroxides electrocatalysts with efficient hydrogen generation.
基金supported in part by the International Collaborative R&D Program (N0000678)the Industrial Strategic Technology Development Program (10041681) funded by the Ministry of Trade, Industry and Energy of Korea
文摘Spatial distributions of plasma parameters such as electron density, electron temperature and electric potential were investigated using a commercial simulation software （COMSOLTM） to predict the effects of antenna configuration in a large area inductively cou- pled plasma （ICP） system for flat panel displays. Nine planar antenna sets were evenly placed above a ceramic window. While the electron density was influenced by both the input current and gas pressure, the electron temperature and electric potential were dominantly affected by the gas pressure.
文摘Single- and double-null divertor configurations in HL-2A are simulated by SWEQU equilibrium code. Lower divertor discharges in the first physics campaign have been achieved by two kinds of power supply method of multipole-field coils. Single-null divertor configuration has been identified by visible photography, target probe arrays and the reconstructed magnetic surface. Magnetic separatrix and minor radius of plasma column are obtained by a reconstructed code of multiple current filaments using 18 Mirnov signals.
