Large eddy simulation cooperated with the second order full extension ETG(Euler-Taylor-Galerkin) finite element method was applied to simulate the flow around two square cylinders arranged side by side at a spacing ra...Large eddy simulation cooperated with the second order full extension ETG(Euler-Taylor-Galerkin) finite element method was applied to simulate the flow around two square cylinders arranged side by side at a spacing ratio of (1.5.) The second order full extension ETG finite element method was developed by Wang and He. By means of Taylor expansion of terms containing time derivative, time derivative is replaced by space derivative. The function of it is equal to introducing an artificial viscosity term. The streamlines of the flow at different moments were obtained. The time history of drag coefficient, lift coefficient and the streamwise velocity on the symmetrical points were presented. Furthermore, the symmetrical problem of the frequency spectrum of flow around two square cylinders arranged side by side were studied by using the spectral analysis technology. The data obtained at the initial stage are excluded in order to avoid the influence of initial condition on the results. The power spectrums of drag coefficient, lift coefficient, the streamwise velocity on the symmetrical points were analyzed respectively. The results show that although the time domain process of dynamic parameters is non-symmetrical, the frequency domain process of them is symmetrical under the symmetrical boundary conditions.展开更多
An innovative design of electric suspensions was developed in this study to help realize slow active suspension easily and quickly.This design was driven by screw through double slider-rod arranged symmetrically as a ...An innovative design of electric suspensions was developed in this study to help realize slow active suspension easily and quickly.This design was driven by screw through double slider-rod arranged symmetrically as a substitute for two springs.Based on a mathematical modeling,suspension parameters were introduced for a certain type of wheeled vehicles.The functions and its mechanism in regulating terrain clearance and adjusting attitudes were subsequently explained respectively,together with its semi-active control mechanism and characteristics In conclusion,our data in the study show that the new mechanical design of suspensions not only could realize adjusting terrain clearance and static vehicle pose,but also had an ideal stiffness that could realize a semi-active suspension function through adjusting suspension＇s stiffness.Therefore it can bequite suitable for off-road wheeled vehicles and military wheeled vehicles.展开更多
cases of postherpetic neuralgia were treated with arranged electro acupuncture and 30 cases with medicine as control. All cases were HIV carriers. The 6 point behavioral rating scale (BRS 6) was used to observe the ef...cases of postherpetic neuralgia were treated with arranged electro acupuncture and 30 cases with medicine as control. All cases were HIV carriers. The 6 point behavioral rating scale (BRS 6) was used to observe the effect before and after treatment. The results indicate arranged electro acupuncture can cure or reduce the severe pain of postherpetic neuralgia of HIV carriers and the effect was better than medicine.展开更多
The numerical method is used to calculate the flow around two square cylinders arranged side-by-side and the mean and fluctuating aerodynamic forces, and Strouhal numbers and power spectrum of lift force and drag forc...The numerical method is used to calculate the flow around two square cylinders arranged side-by-side and the mean and fluctuating aerodynamic forces, and Strouhal numbers and power spectrum of lift force and drag force are obtained. An improved MAC method proposed by Chen Suqin et al.,which uses three order upwind scheme to discretize the convection term and uses multigrid method to solve the Poisson equation for pressure is applied to simulate the flow around two square cylinders arranged side-by-side. Results show that the interference characteristic of two square cylinders arranged side-by-side is completely different with the different spacing ratio. When the spacing ratio is smaller than a certain critical value, the gap flow between two cylinders is biased to one side in a stable or unstable manner.展开更多
Taking the three-riser group arranged in tandem as the research subject,an experimental study was carried out on the risers arranged in tandem.The purpose is to explore the sensitivity of the dynamic response of each ...Taking the three-riser group arranged in tandem as the research subject,an experimental study was carried out on the risers arranged in tandem.The purpose is to explore the sensitivity of the dynamic response of each riser to spacing ratio and reveal the physical mechanism of riser groups under the interference effect.The spacing ratios of the adj acent risers are 4.0,5.0,6.0,and 8.0.At the spacing between the risers of 4.0D,the strong feedback effect increases the cross-flow(CF) displacement amplitude of the upstream riser.The shielding effect is the key factor affecting the interference effect on the midstream and downstream risers.At low reduced velocities,the shielding area initially appears,the displacement amplitude of the midstream and downstream risers varies greatly,the vibration of the two risers is still dominated by the first-order mode,and the transition between adjacent vibration modes is restrained.The multi-frequency superposition phenomenon is very significant at high reduced velocities.The most sensitive interference spacing under the test conditions is obtained.Due to the separation of the incoming flow and the double shielding effect of the upstream and midstream risers,the regular vortex-induced vibration in the wake area of the downstream riser is broken,and the vibration in the two directions is weakened.In general,the interference effect is more significant for the CF vibration of the three-riser groups than the in-line(IL) vibration.展开更多
This study proposed a design and optimization strategy for a tandem arranged cascade using the Non-dominated Sorting Genetic Algorithm(NSGA) Ⅱ multi-objective optimization algorithm and Back Propagation(BP) neural ne...This study proposed a design and optimization strategy for a tandem arranged cascade using the Non-dominated Sorting Genetic Algorithm(NSGA) Ⅱ multi-objective optimization algorithm and Back Propagation(BP) neural network technology. The NASA Stage 35 was employed as the initial bench mark in the present study and five geometric control parameters were working as the optimization parameters aiming to enhance the aerodynamic performance in terms of total pressure rise and efficiency. Results showed that the feasibility and capability of the proposed optimization strategy was successfully examined. In view of the fact that the initial tandem cascade(directly scaling down from NASA Stage 35) cannot guarantee the aerodynamic performance, first optimization trial was conducted to optimize the initial design. Results showed that the optimum can improve the flow quality whereas the separation on the blade is decayed or even eliminated particularly at the tip and root regions. However, compared with the initial tandem design, the enhancement in total pressure ratio(0.47%) and efficiency(1%) are too small to be noticed. Second investigation was particularly emphasizing on a high turning tandem compressor with an increment by 28°. The pressure rise and efficiency were augmented by 1.44% and 2.34%(compared to the initial tandem design), respectively. An important conclusion can be drawn that the optimization strategy is worthy to be used in high turning compressors with a considerable performance improvement.展开更多
A uniform arrangement of individual piles is commonly adopted in the conventional pile group foundation,and basin-shaped settlement is often observed in practice.Large differential settlement of pile groups will decre...A uniform arrangement of individual piles is commonly adopted in the conventional pile group foundation,and basin-shaped settlement is often observed in practice.Large differential settlement of pile groups will decrease the use-safety requirements of building,even cause the whole-building tilt or collapse.To reduce differential settlement among individual piles,non-uniformly arranged pile groups can be adopted.This paper presents a finite element analysis on the response of pile groups with different layouts of individual piles in pile groups.Using the userdefined subroutine FRIC as the secondary development platform,a softening model of skin friction and a hyperbolic model of end resistance are introduced into the contact pair calculation of ABAQUS software.As to the response analysis of a single pile,the reliability of the proposed secondary development method of ABAQUS software is verified using an iterative computer program.The reinforcing effects of individual piles is then analyzed using the present finite element analysis.Furthermore,the response of non-uniformly arranged pile groups,e.g.,individual piles with variable length and individual piles with variable diameter,is analyzed using the proposed numerical analysis method.Some suggestions on the layout of individual piles are proposed to reduce differential settlement and make full use of the bearing capacity of individual piles in pile groups for practical purposes.展开更多
To ensure the safe transportation of radioactive materials,numerous countries have established specific standards.For the transfer of fissile materials,it is imperative that the material within the packaging remains i...To ensure the safe transportation of radioactive materials,numerous countries have established specific standards.For the transfer of fissile materials,it is imperative that the material within the packaging remains in a subcritical state during routine,normal,and accidental transport conditions.In the event of an accident,the rods within the storage tank may become rearranged,introducing uncertainty that must be accounted for to ensure that criticality analysis results are conservative.Historically,this uncertainty was addressed overly conservatively due to limited research on non-uniform arrangement scenarios,which proved unsuitable for criticality safety analysis of spent fuel packages.This paper introduced three distinct methods to non-uniformly rearrange fuel rods—Uniform Arrangement by Blocks,Layer-by-Layer Determination,and Birdcage Deformation—and meticulously evaluates the influences of rod rearrangement on the effective multiplication factor of neutrons,k eff,utilizing the Monte Carlo method.Ultimately,this study presents a holistic method capable of encompassing the entire spectrum of potential effects stemming from the rearrangement of fuel rods during rods mispositioning accident.By augmenting the safety margin,this approach proves to be adeptly suited for the criticality safety analysis of nuclear fuel transport containers.展开更多
Word cloud visualization is a compelling graphical representation that visually depicts the frequency of words within a given text or dataset[1].Research on word clouds focuses on two main aspects.The first emphasizes...Word cloud visualization is a compelling graphical representation that visually depicts the frequency of words within a given text or dataset[1].Research on word clouds focuses on two main aspects.The first emphasizes processing words,such as using the latent Dirichlet allocation(LDA)algorithm to uncover topics in the documents[2],while the second involves visual impact through striking word arrangements[3,4].In the realm of extensive biomedical data,effectiveknowledge delivery to biologists is crucial.展开更多
Eliminating the nonselective permeation path inside the mixed-matrix membranes(MMMs)is critical for fabrication of gas separation membranes.We demonstrate that by utilizing the phase separation of block copolymers,we ...Eliminating the nonselective permeation path inside the mixed-matrix membranes(MMMs)is critical for fabrication of gas separation membranes.We demonstrate that by utilizing the phase separation of block copolymers,we are able to introduce metal-organic polyhedrons(MOPs)with precise pore sizes into a polymer matrix and form an ordered layered structure.We also prove that,by arranging MOP cages into a continuous nanosheet-like layer structure,we are able to generate repeated MOP-effective pathways and deplete the MOP-free permeation pathways,thus enhancing the gas-separation efficiency of MMMs.展开更多
Foreign-funded overseas industrial parks(OIPs)are crucial for attracting foreign investment and promoting globalization in developing countries.However,large-scale land acquisition for these parks generates conflicts ...Foreign-funded overseas industrial parks(OIPs)are crucial for attracting foreign investment and promoting globalization in developing countries.However,large-scale land acquisition for these parks generates conflicts between developers and local stakeholders,increasing development costs.A qualitative multicase study was conducted in this study to analyze the land transaction trajectories of China's OIPs.Four OIPs were selected to reveal the underlying mechanisms from the perspectives of institutional arrangements,governance mechanisms,and enterprise heterogeneity.The findings indicate that in host countries with insufficient institutional development,local governments are more inclined to directly engage in OIP land acquisition.High-level intergovernmental mechanisms facilitate land acquisition processes,although their efficacy depends largely on administrative power allocation across parks in host countries.The results also indicate that enterprise characteristics significantly influence land acquisition,where microscale private enterprises lacking political connections often employ low-cost,bottom-up strategies by leveraging international experience.In summary,policy-makers in developing countries should prioritize enhancing OIP governance to mitigate transaction costs,promote diversified land supply,and optimize land allocation.By depicting China's OIP land acquisition processes,this study deepens the academic understanding of OIP governance in developing countries and related international land transactions,offering practical OIP management insights for governments in both host and parent countries.展开更多
All-inorganic lead-free Cs_(2)AgBiBr_(6) double perovskite is a promising semiconductor for photodetection in daily life due to its outstanding photoelectrical properties,non-toxicity,and high stability.Compared with ...All-inorganic lead-free Cs_(2)AgBiBr_(6) double perovskite is a promising semiconductor for photodetection in daily life due to its outstanding photoelectrical properties,non-toxicity,and high stability.Compared with its organic-inorganic hybrid analogs,the fabrication method for Cs_(2)AgBiBr_(6) is not well developed.Solution-processed Cs_(2)AgBiBr_(6) films usually exhibit loosened morphology with small grains,many pin-holes,and abundant nonradiative defects.In particular,the disordered arrangements of Ag/Bi cations are thermodynamically favorable in Cs_(2)AgBiBr_(6),which contribute to the formation of self-trapped excitons and heavily restrict charge transport.Here in this work,a modified green antisolvent engineering strat-egy with phenethyl-ammonium bromide(PEABr)dissolved isopropyl alcohol(IPA)solution is developed to prepare high-quality Cs_(2)AgBiBr_(6) films.The PEABr/IPA treatment results in compact morphology with enlarged grains and promotes the ordered arrangements of Ag/Bi cations with improved charge transport.Through optimization,the target self-powered photodetector exhibits a responsivity of 0.38 AW−1,a spe-cific detectivity of 1.9×10^(12) Jones,a response time of 54/63μs,and a linear dynamic range of 107 dB,which is among the best-performing self-powered photodetectors based on lead-free perovskites.Our work thus provides a facile and green fabrication method for high-performance optoelectronic devices based on eco-friendly Cs_(2)AgBiBr_(6).展开更多
Thick and highly conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate films with ideal porous structure are fulfilling as electrodes for supercapacitors.However,the homogeneous micro-structure without the...Thick and highly conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate films with ideal porous structure are fulfilling as electrodes for supercapacitors.However,the homogeneous micro-structure without the aid of templates or composite presents a significant obstacle,due to the intrinsic softness of the dominant PSS component.In this study,we have successfully developed a porous configuration by employing a solvothermal approach with ethylene glycol(EG)as the solvent.The synergistic action of elevated pressure and temperature was crucial in prompting EG to tailor the microstructure of the PEDOT:PSS films by removing non-conductive PSS chains and improving PEDOT crystallinity,and the formation of a porous network.The resulting porous PEDOT:PSS films exhibited a high conductivity of 1644 S cm^(-1)and achieved a volumetric capacitance record of 270 F cm^(-3),markedly exceeding previous records.The flexible all-solid-state supercapacitor assembled by the films had an outstanding volumetric capacitance of 97.8 F cm^(-3)and an energy density of 8.7 mWh cm^(-3),which is best one for pure PEDOT:PSS-based supercapacitors.Grazing-incidence wide-angle X-ray scattering,X-ray photoelectron spectroscopy,and other characterizations were carried out to characterize the structure evolution.This work offers an effective novel method for conducting polymer morphology control and promotes PEDOT:PSS applications in energy storage field.展开更多
Atmospheric particle adsorption on insulator surfaces,coupled with humid environments,significantly affects contamination flashover,necessitating a clear understanding of the electric field distribution on insulator s...Atmospheric particle adsorption on insulator surfaces,coupled with humid environments,significantly affects contamination flashover,necessitating a clear understanding of the electric field distribution on insulator surfaces with adsorbed particles.This is crucial for accurately assessing insulator safety and informing critical decision-making.Although previous research has demonstrated that particle arrangement significantly influences the electric field distribution around transmission lines,an in-depth analysis of its effects on insulator surfaces remains lacking.To address this gap,this study establishes a composite insulator model to examine how three types of spherical contamination layers affect the electric field distribution on insulator surfaces under varying environmental conditions.The results reveal that in dry environments,the electric field strength at the apex of single-particle contamination layers increases with the particle size and relative permittivity.For the double-particle contamination layers,the electric field intensity on the insulator surface decreases as the particle spacing increases,and larger particles are more likely to attract smaller charged particles.For triple-particle contamination layers arranged in a triangular pattern,the maximum surface field strength is nearly double that of the chain-arranged particles.Furthermore,within the chain-arranged triple-particle contamination layers,a large-small-large size arrangement has a more pronounced impact on the surface electric field than a small-large-small size arrangement.In humid environments,the surface electric field strength of insulators decreases with increasing contamination levels.These findings are of significant theoretical and practical importance for ensuring the safe operation of power systems.展开更多
Liquefied natural gas storage and transportation as well as space propulsion systems have sparked inter-est in the martensitic transformation and behaviours of 316 L stainless steels(SS)under ultra-cryogenic deformati...Liquefied natural gas storage and transportation as well as space propulsion systems have sparked inter-est in the martensitic transformation and behaviours of 316 L stainless steels(SS)under ultra-cryogenic deformation.In this study,high-resolution transmission electron microscopy(HRTEM)and molecular dy-namics(MD)simulations were used to investigate the atomic arrangements and crystalline defects of deformation-induced γ-austenite→ε-martensite→α'-martensite and γ→α'martensitic transforma-tions in 316 L SS at 15 and 173 K.Theγ→εtransformation involves the glide of Shockley partial dislocations on(111)γplanes without a change in atomic spacing.The formation of anα'inclusion in a singleε-band is achieved by a continuous lattice distortion,accompanied by the formation of a tran-sition zone ofα'and the expansion of the average atomic spacings due to dislocation shuffling.Asα'grows further intoγ,the orientation relationship(OR)of theα'changes by lattice bending.This pro-cess follows the Bogers-Burgers-Olson-Cohen model despite it not occurring on intersecting shear bands.Stacking faults and twins can also serve as nucleation sites forα'at 173 K.We also found that direct transformation of γ→α'occurs by the glide of √6aγ[11(2)]/12 dislocations on every(111)γplane with misfit dislocations.Overall,this study provides,for the first time,insights into the atomic-scale mech-anisms of various two-step and one-step martensitic transformations induced by cryogenic deformation and corresponding local strain,enhancing our understanding of the role of martensitic transformation under ultra-cryogenic-temperature deformation in controlling the properties.展开更多
The miniaturization and high-power density of electronic devices presents new challenges in thermal management.The precise control of microstructure arrangement,particularly in boron nitride nanosheets(BNNS),is essent...The miniaturization and high-power density of electronic devices presents new challenges in thermal management.The precise control of microstructure arrangement,particularly in boron nitride nanosheets(BNNS),is essential for achieving efficient heat dissipation in highly thermally conductive composites within electrically insulating package.In this work,manganese ferrite was hydrothermally synthesized on BNNS,creating a layered structure in a magnetically responsive nanohybrid material named BNNS@M.This material was then integrated into a waterborne polyurethane(WPU)solution and shaped under a magnetic field to produce thermally conductive film.By altering the magnetic field direction,the mi-crostructure orientation of BNNS@M was controlled,resulting in anisotropic thermally conductive com-posite films with horizontal and vertical orientations.Specifically,under a vertical magnetic field,the film 30-Ve-BNNS@WPU,containing 30 wt.%BNNS@M,achieved a through-plane thermal conductivity of 8.5 W m^(−1)K^(−1)and an in-plane thermal conductivity of 1.8 W m^(−1)K^(−1),showcasing significant anisotropic thermal conductivity.Meanwhile,these films demonstrated excellent thermal stability,mechanical per-formance,and flame retardancy.Furthermore,employing Foygel’s theory elucidated the impact of filler arrangement on thermal conductivity mechanisms and the actual application of 5 G device chips and LED lamps emphasizing the potential of these thermally conductive films in thermal management appli-cations.This investigation contributes valuable design concepts and foundations for the development of anisotropic thermally conductive composites suitable for electron thermal management.展开更多
The lack of systematic and scientific top-level arrangement in the field of civil aircraft flight test leads to the problems of long duration and high cost.Based on the flight test activity,mathematical models of flig...The lack of systematic and scientific top-level arrangement in the field of civil aircraft flight test leads to the problems of long duration and high cost.Based on the flight test activity,mathematical models of flight test duration and cost are established to set up the framework of flight test process.The top-level arrangement for flight test is optimized by multi-objective algorithm to reduce the duration and cost of flight test.In order to verify the necessity and validity of the mathematical models and the optimization algorithm of top-level arrangement,real flight test data is used to make an example calculation.Results show that the multi-objective optimization results of the top-level flight arrangement are better than the initial arrangement data,which can shorten the duration,reduce the cost,and improve the efficiency of flight test.展开更多
In nature,cavitation bubbles typically appear in clusters,engaging in interactions that create a variety of dynamicmotion patterns.To better understand the behavior ofmultiple bubble collapses and the mechanisms of in...In nature,cavitation bubbles typically appear in clusters,engaging in interactions that create a variety of dynamicmotion patterns.To better understand the behavior ofmultiple bubble collapses and the mechanisms of interbubble interaction,this study employs molecular dynamics simulation combined with a coarse-grained force field.By focusing on collapsemorphology,local density,and pressure,it elucidates how the number and arrangement of bubbles influence the collapse process.The mechanisms behind inter-bubble interactions are also considered.The findings indicate that the collapse speed of unbounded bubbles located in lateral regions is greater than that of the bubbles in the center.Moreover,it is shown that asymmetrical bubble distributions lead to a shorter collapse time overall.展开更多
1T-MoS_(2)nanosheets,with metallic conductivity and high capacity,hold great potential for lithium-ion capacitors(LICs),but suffer from sluggish reaction kinetics due to dense stacking.Herein,1T-MoS_(2)nanosheets with...1T-MoS_(2)nanosheets,with metallic conductivity and high capacity,hold great potential for lithium-ion capacitors(LICs),but suffer from sluggish reaction kinetics due to dense stacking.Herein,1T-MoS_(2)nanosheets with enlarged interlayer spacing,vertically bonded to reduced graphene oxide(rGO)(1T-MoS_(2)/rGO),were designed using a hydrothermal-assisted dispersion and intercalation strategy.The active nitrogen species derived from N,N-dimethylformamide(DMF)not only bridge the rGO and MoS_(2)through strong Mo-N-C bonds to promote the formation of dispersed MoS_(2)nanosheets,but also intercalate into the MoS_(2)structure,further enlarging the interlayer spacing.This unique structure synergistically enhances meso-and microscale mass transfer outside and inside of the few-layered nanosheets,significantly improving electrochemical reaction kinetics and reducing the kinetic mismatch between the anode and cathode.Consequently,the resulting 1T-MoS_(2)/rGO achieves a capacity of 500 mAh g^(-1)after 500 cycles at 5 A g^(-1)and a high rate performance of 587 mAh g^(-1)at a high rate of 10 A g^(-1).Moreover,the assembled 3D vertical 1T-MoS_(2)/rGO//AC LIC delivers a high energy density of 100.3 Wh kg^(-1)at a power density of1.0 kW kg^(-1),and long cycle stability with capacity retention as high as 91.02%after 5000 cycles at 2 A g^(-1).This work provides a generalizable strategy for engineering two-dimensional material-based electrodes,offering new insights into high-performance energy storage systems.展开更多
The migration and transformation of hexavalent chromium(Cr(VI))in the environment are regulated by pyrite(FeS2).However,variations in pyrite crystal facets influence the adsorption behavior and electron transfer betwe...The migration and transformation of hexavalent chromium(Cr(VI))in the environment are regulated by pyrite(FeS2).However,variations in pyrite crystal facets influence the adsorption behavior and electron transfer between pyrite and Cr(VI),thereby impacting the Cr(VI)reduction performance.Herein,two naturally common facets of pyritewere synthesized hydrothermally to investigate the facet-dependent mechanisms of Cr(VI)reduction.The experimental results revealed that the{111}facet exhibited approximately 1.30–1.50 times higher efficiency in Cr(VI)reduction compared to the{100}facet.Surface analyses and electrochemical results indicated that{111}facet displayed a higher iron-sulfur oxidation level,which was affected by its superior electrochemical properties during the reaction with Cr(VI).Density functional theory(DFT)calculations demonstrated that the narrower band gap and lower work function on{111}facet were more favorable for the electron transfer between Fe(II)and Cr(VI).Furthermore,different adsorption configurations were observed on{100}and{111}surfaces due to the unique arrangements of Fe and S atoms.Specifically,O atoms in Cr_(2)O_(7)^(2−)directly bound with the S sites on{100}but the Fe sites on{111}.According to the density of states(DOS),the Fe site had better reactivity than the S site in the reaction,which appeared to be related to the fracture of S-S bonds.Additionally,the adsorption configuration of Cr_(2)O_(7)^(2−)on{111}surface showed a stronger adsorption energy and a more stable coordination mode,favoring subsequent Cr(VI)reduction process.These findings provide an in-depth analysis of facet-dependent mechanisms underlying Cr(VI)reduction behavior,offering new insights into studying environmental interactions between heavy metals and natural minerals.展开更多
文摘Large eddy simulation cooperated with the second order full extension ETG(Euler-Taylor-Galerkin) finite element method was applied to simulate the flow around two square cylinders arranged side by side at a spacing ratio of (1.5.) The second order full extension ETG finite element method was developed by Wang and He. By means of Taylor expansion of terms containing time derivative, time derivative is replaced by space derivative. The function of it is equal to introducing an artificial viscosity term. The streamlines of the flow at different moments were obtained. The time history of drag coefficient, lift coefficient and the streamwise velocity on the symmetrical points were presented. Furthermore, the symmetrical problem of the frequency spectrum of flow around two square cylinders arranged side by side were studied by using the spectral analysis technology. The data obtained at the initial stage are excluded in order to avoid the influence of initial condition on the results. The power spectrums of drag coefficient, lift coefficient, the streamwise velocity on the symmetrical points were analyzed respectively. The results show that although the time domain process of dynamic parameters is non-symmetrical, the frequency domain process of them is symmetrical under the symmetrical boundary conditions.
基金Supported by the Ministerial Level Research Foundation(4030.4)
文摘An innovative design of electric suspensions was developed in this study to help realize slow active suspension easily and quickly.This design was driven by screw through double slider-rod arranged symmetrically as a substitute for two springs.Based on a mathematical modeling,suspension parameters were introduced for a certain type of wheeled vehicles.The functions and its mechanism in regulating terrain clearance and adjusting attitudes were subsequently explained respectively,together with its semi-active control mechanism and characteristics In conclusion,our data in the study show that the new mechanical design of suspensions not only could realize adjusting terrain clearance and static vehicle pose,but also had an ideal stiffness that could realize a semi-active suspension function through adjusting suspension＇s stiffness.Therefore it can bequite suitable for off-road wheeled vehicles and military wheeled vehicles.
文摘cases of postherpetic neuralgia were treated with arranged electro acupuncture and 30 cases with medicine as control. All cases were HIV carriers. The 6 point behavioral rating scale (BRS 6) was used to observe the effect before and after treatment. The results indicate arranged electro acupuncture can cure or reduce the severe pain of postherpetic neuralgia of HIV carriers and the effect was better than medicine.
文摘The numerical method is used to calculate the flow around two square cylinders arranged side-by-side and the mean and fluctuating aerodynamic forces, and Strouhal numbers and power spectrum of lift force and drag force are obtained. An improved MAC method proposed by Chen Suqin et al.,which uses three order upwind scheme to discretize the convection term and uses multigrid method to solve the Poisson equation for pressure is applied to simulate the flow around two square cylinders arranged side-by-side. Results show that the interference characteristic of two square cylinders arranged side-by-side is completely different with the different spacing ratio. When the spacing ratio is smaller than a certain critical value, the gap flow between two cylinders is biased to one side in a stable or unstable manner.
基金financially supported by the National Natural Science Foundation of China (Grant No. 42177167)the Natural Science Foundation of Shandong Province (Grant No. ZR2019QEE008)。
文摘Taking the three-riser group arranged in tandem as the research subject,an experimental study was carried out on the risers arranged in tandem.The purpose is to explore the sensitivity of the dynamic response of each riser to spacing ratio and reveal the physical mechanism of riser groups under the interference effect.The spacing ratios of the adj acent risers are 4.0,5.0,6.0,and 8.0.At the spacing between the risers of 4.0D,the strong feedback effect increases the cross-flow(CF) displacement amplitude of the upstream riser.The shielding effect is the key factor affecting the interference effect on the midstream and downstream risers.At low reduced velocities,the shielding area initially appears,the displacement amplitude of the midstream and downstream risers varies greatly,the vibration of the two risers is still dominated by the first-order mode,and the transition between adjacent vibration modes is restrained.The multi-frequency superposition phenomenon is very significant at high reduced velocities.The most sensitive interference spacing under the test conditions is obtained.Due to the separation of the incoming flow and the double shielding effect of the upstream and midstream risers,the regular vortex-induced vibration in the wake area of the downstream riser is broken,and the vibration in the two directions is weakened.In general,the interference effect is more significant for the CF vibration of the three-riser groups than the in-line(IL) vibration.
基金financially supported by the National Natural Science Foundation of China(No.51376150)
文摘This study proposed a design and optimization strategy for a tandem arranged cascade using the Non-dominated Sorting Genetic Algorithm(NSGA) Ⅱ multi-objective optimization algorithm and Back Propagation(BP) neural network technology. The NASA Stage 35 was employed as the initial bench mark in the present study and five geometric control parameters were working as the optimization parameters aiming to enhance the aerodynamic performance in terms of total pressure rise and efficiency. Results showed that the feasibility and capability of the proposed optimization strategy was successfully examined. In view of the fact that the initial tandem cascade(directly scaling down from NASA Stage 35) cannot guarantee the aerodynamic performance, first optimization trial was conducted to optimize the initial design. Results showed that the optimum can improve the flow quality whereas the separation on the blade is decayed or even eliminated particularly at the tip and root regions. However, compared with the initial tandem design, the enhancement in total pressure ratio(0.47%) and efficiency(1%) are too small to be noticed. Second investigation was particularly emphasizing on a high turning tandem compressor with an increment by 28°. The pressure rise and efficiency were augmented by 1.44% and 2.34%(compared to the initial tandem design), respectively. An important conclusion can be drawn that the optimization strategy is worthy to be used in high turning compressors with a considerable performance improvement.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51778345 and 41877252)the Shandong Provincial Natural Science Foundation for Distinguished Young Scholars(No.JQ201811)+1 种基金the Key Laboratory of Geotechnical and Underground Engineering(Tongji University),Ministry of Education(No.KLE-TJGE-B1802)the Young Scholars Program of Shandong University(No.2017WLJH32).
文摘A uniform arrangement of individual piles is commonly adopted in the conventional pile group foundation,and basin-shaped settlement is often observed in practice.Large differential settlement of pile groups will decrease the use-safety requirements of building,even cause the whole-building tilt or collapse.To reduce differential settlement among individual piles,non-uniformly arranged pile groups can be adopted.This paper presents a finite element analysis on the response of pile groups with different layouts of individual piles in pile groups.Using the userdefined subroutine FRIC as the secondary development platform,a softening model of skin friction and a hyperbolic model of end resistance are introduced into the contact pair calculation of ABAQUS software.As to the response analysis of a single pile,the reliability of the proposed secondary development method of ABAQUS software is verified using an iterative computer program.The reinforcing effects of individual piles is then analyzed using the present finite element analysis.Furthermore,the response of non-uniformly arranged pile groups,e.g.,individual piles with variable length and individual piles with variable diameter,is analyzed using the proposed numerical analysis method.Some suggestions on the layout of individual piles are proposed to reduce differential settlement and make full use of the bearing capacity of individual piles in pile groups for practical purposes.
文摘To ensure the safe transportation of radioactive materials,numerous countries have established specific standards.For the transfer of fissile materials,it is imperative that the material within the packaging remains in a subcritical state during routine,normal,and accidental transport conditions.In the event of an accident,the rods within the storage tank may become rearranged,introducing uncertainty that must be accounted for to ensure that criticality analysis results are conservative.Historically,this uncertainty was addressed overly conservatively due to limited research on non-uniform arrangement scenarios,which proved unsuitable for criticality safety analysis of spent fuel packages.This paper introduced three distinct methods to non-uniformly rearrange fuel rods—Uniform Arrangement by Blocks,Layer-by-Layer Determination,and Birdcage Deformation—and meticulously evaluates the influences of rod rearrangement on the effective multiplication factor of neutrons,k eff,utilizing the Monte Carlo method.Ultimately,this study presents a holistic method capable of encompassing the entire spectrum of potential effects stemming from the rearrangement of fuel rods during rods mispositioning accident.By augmenting the safety margin,this approach proves to be adeptly suited for the criticality safety analysis of nuclear fuel transport containers.
基金supported by the National Key R&D Program of China(2022YFC2704304 and 2021YFF0702000)the National Natural Science Foundation of China(32341020 and 32341021)+1 种基金Hubei Innovation Group Project(2021CFA005)the Research Core Facilities for Life Science(HUST).
文摘Word cloud visualization is a compelling graphical representation that visually depicts the frequency of words within a given text or dataset[1].Research on word clouds focuses on two main aspects.The first emphasizes processing words,such as using the latent Dirichlet allocation(LDA)algorithm to uncover topics in the documents[2],while the second involves visual impact through striking word arrangements[3,4].In the realm of extensive biomedical data,effectiveknowledge delivery to biologists is crucial.
基金supported by Guangdong Natural Science Foundation(No.2018B030306039)the Recruitment Program of Guangdong(No.2016ZT06C322)and the 111 Project(No.B18023).
文摘Eliminating the nonselective permeation path inside the mixed-matrix membranes(MMMs)is critical for fabrication of gas separation membranes.We demonstrate that by utilizing the phase separation of block copolymers,we are able to introduce metal-organic polyhedrons(MOPs)with precise pore sizes into a polymer matrix and form an ordered layered structure.We also prove that,by arranging MOP cages into a continuous nanosheet-like layer structure,we are able to generate repeated MOP-effective pathways and deplete the MOP-free permeation pathways,thus enhancing the gas-separation efficiency of MMMs.
基金Philosophy and Social Science Planning Projects in Yunnan Province,No.QN202428China Postdoctoral Science Foundation,No.2024M752918。
文摘Foreign-funded overseas industrial parks(OIPs)are crucial for attracting foreign investment and promoting globalization in developing countries.However,large-scale land acquisition for these parks generates conflicts between developers and local stakeholders,increasing development costs.A qualitative multicase study was conducted in this study to analyze the land transaction trajectories of China's OIPs.Four OIPs were selected to reveal the underlying mechanisms from the perspectives of institutional arrangements,governance mechanisms,and enterprise heterogeneity.The findings indicate that in host countries with insufficient institutional development,local governments are more inclined to directly engage in OIP land acquisition.High-level intergovernmental mechanisms facilitate land acquisition processes,although their efficacy depends largely on administrative power allocation across parks in host countries.The results also indicate that enterprise characteristics significantly influence land acquisition,where microscale private enterprises lacking political connections often employ low-cost,bottom-up strategies by leveraging international experience.In summary,policy-makers in developing countries should prioritize enhancing OIP governance to mitigate transaction costs,promote diversified land supply,and optimize land allocation.By depicting China's OIP land acquisition processes,this study deepens the academic understanding of OIP governance in developing countries and related international land transactions,offering practical OIP management insights for governments in both host and parent countries.
基金supported by the National Natural Science Foundation of China(No.61704154)the Natural Science Foundation of Zhejiang Province(No.LY20F040006)the Open Foundation of the State Key Laboratory of Fluid Power and Mecha-tronic Systems(No.GZKF-202313).
文摘All-inorganic lead-free Cs_(2)AgBiBr_(6) double perovskite is a promising semiconductor for photodetection in daily life due to its outstanding photoelectrical properties,non-toxicity,and high stability.Compared with its organic-inorganic hybrid analogs,the fabrication method for Cs_(2)AgBiBr_(6) is not well developed.Solution-processed Cs_(2)AgBiBr_(6) films usually exhibit loosened morphology with small grains,many pin-holes,and abundant nonradiative defects.In particular,the disordered arrangements of Ag/Bi cations are thermodynamically favorable in Cs_(2)AgBiBr_(6),which contribute to the formation of self-trapped excitons and heavily restrict charge transport.Here in this work,a modified green antisolvent engineering strat-egy with phenethyl-ammonium bromide(PEABr)dissolved isopropyl alcohol(IPA)solution is developed to prepare high-quality Cs_(2)AgBiBr_(6) films.The PEABr/IPA treatment results in compact morphology with enlarged grains and promotes the ordered arrangements of Ag/Bi cations with improved charge transport.Through optimization,the target self-powered photodetector exhibits a responsivity of 0.38 AW−1,a spe-cific detectivity of 1.9×10^(12) Jones,a response time of 54/63μs,and a linear dynamic range of 107 dB,which is among the best-performing self-powered photodetectors based on lead-free perovskites.Our work thus provides a facile and green fabrication method for high-performance optoelectronic devices based on eco-friendly Cs_(2)AgBiBr_(6).
基金supported by the National Natural Science Foundation of China(No.51902134)Zhejiang Public Welfare Technology Application Research Program(No.LGJ22B040001)+1 种基金the Innovation Jiaxing Elite Leading Plan 2020,Jiaxing Public Welfare Technology Application Research Program(No.2023AY11051)the Fundamental Research Funds for the Jiaxing University(No.CD70519019,No.CDN70518005,No.CD70623018).
文摘Thick and highly conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate films with ideal porous structure are fulfilling as electrodes for supercapacitors.However,the homogeneous micro-structure without the aid of templates or composite presents a significant obstacle,due to the intrinsic softness of the dominant PSS component.In this study,we have successfully developed a porous configuration by employing a solvothermal approach with ethylene glycol(EG)as the solvent.The synergistic action of elevated pressure and temperature was crucial in prompting EG to tailor the microstructure of the PEDOT:PSS films by removing non-conductive PSS chains and improving PEDOT crystallinity,and the formation of a porous network.The resulting porous PEDOT:PSS films exhibited a high conductivity of 1644 S cm^(-1)and achieved a volumetric capacitance record of 270 F cm^(-3),markedly exceeding previous records.The flexible all-solid-state supercapacitor assembled by the films had an outstanding volumetric capacitance of 97.8 F cm^(-3)and an energy density of 8.7 mWh cm^(-3),which is best one for pure PEDOT:PSS-based supercapacitors.Grazing-incidence wide-angle X-ray scattering,X-ray photoelectron spectroscopy,and other characterizations were carried out to characterize the structure evolution.This work offers an effective novel method for conducting polymer morphology control and promotes PEDOT:PSS applications in energy storage field.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12064034 and 11562017)the Leading Talents Program of Science and Technology Innovation in Ningxia Hui Autonomous Region,China(Grant No.2020GKLRLX08)the Natural Science Foundation of Ningxia Hui Autonomous Region,China(Grant No.2024AAC05040)。
文摘Atmospheric particle adsorption on insulator surfaces,coupled with humid environments,significantly affects contamination flashover,necessitating a clear understanding of the electric field distribution on insulator surfaces with adsorbed particles.This is crucial for accurately assessing insulator safety and informing critical decision-making.Although previous research has demonstrated that particle arrangement significantly influences the electric field distribution around transmission lines,an in-depth analysis of its effects on insulator surfaces remains lacking.To address this gap,this study establishes a composite insulator model to examine how three types of spherical contamination layers affect the electric field distribution on insulator surfaces under varying environmental conditions.The results reveal that in dry environments,the electric field strength at the apex of single-particle contamination layers increases with the particle size and relative permittivity.For the double-particle contamination layers,the electric field intensity on the insulator surface decreases as the particle spacing increases,and larger particles are more likely to attract smaller charged particles.For triple-particle contamination layers arranged in a triangular pattern,the maximum surface field strength is nearly double that of the chain-arranged particles.Furthermore,within the chain-arranged triple-particle contamination layers,a large-small-large size arrangement has a more pronounced impact on the surface electric field than a small-large-small size arrangement.In humid environments,the surface electric field strength of insulators decreases with increasing contamination levels.These findings are of significant theoretical and practical importance for ensuring the safe operation of power systems.
基金supported by the Henry Royce Institute for Advanced Materials,funded through Engineering and Physical Sciences Research Council(EPSRC)grants EP/R00661X/1,EP/S019367/1,EP/P025021/1,and EP/P025498/1.
文摘Liquefied natural gas storage and transportation as well as space propulsion systems have sparked inter-est in the martensitic transformation and behaviours of 316 L stainless steels(SS)under ultra-cryogenic deformation.In this study,high-resolution transmission electron microscopy(HRTEM)and molecular dy-namics(MD)simulations were used to investigate the atomic arrangements and crystalline defects of deformation-induced γ-austenite→ε-martensite→α'-martensite and γ→α'martensitic transforma-tions in 316 L SS at 15 and 173 K.Theγ→εtransformation involves the glide of Shockley partial dislocations on(111)γplanes without a change in atomic spacing.The formation of anα'inclusion in a singleε-band is achieved by a continuous lattice distortion,accompanied by the formation of a tran-sition zone ofα'and the expansion of the average atomic spacings due to dislocation shuffling.Asα'grows further intoγ,the orientation relationship(OR)of theα'changes by lattice bending.This pro-cess follows the Bogers-Burgers-Olson-Cohen model despite it not occurring on intersecting shear bands.Stacking faults and twins can also serve as nucleation sites forα'at 173 K.We also found that direct transformation of γ→α'occurs by the glide of √6aγ[11(2)]/12 dislocations on every(111)γplane with misfit dislocations.Overall,this study provides,for the first time,insights into the atomic-scale mech-anisms of various two-step and one-step martensitic transformations induced by cryogenic deformation and corresponding local strain,enhancing our understanding of the role of martensitic transformation under ultra-cryogenic-temperature deformation in controlling the properties.
基金supported by the National Natural Science Foundation of China(No.22268025)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011985)the Applied Basic Research Program of Yunnan Province(Nos.202201AT070115,202201BE070001–031).
文摘The miniaturization and high-power density of electronic devices presents new challenges in thermal management.The precise control of microstructure arrangement,particularly in boron nitride nanosheets(BNNS),is essential for achieving efficient heat dissipation in highly thermally conductive composites within electrically insulating package.In this work,manganese ferrite was hydrothermally synthesized on BNNS,creating a layered structure in a magnetically responsive nanohybrid material named BNNS@M.This material was then integrated into a waterborne polyurethane(WPU)solution and shaped under a magnetic field to produce thermally conductive film.By altering the magnetic field direction,the mi-crostructure orientation of BNNS@M was controlled,resulting in anisotropic thermally conductive com-posite films with horizontal and vertical orientations.Specifically,under a vertical magnetic field,the film 30-Ve-BNNS@WPU,containing 30 wt.%BNNS@M,achieved a through-plane thermal conductivity of 8.5 W m^(−1)K^(−1)and an in-plane thermal conductivity of 1.8 W m^(−1)K^(−1),showcasing significant anisotropic thermal conductivity.Meanwhile,these films demonstrated excellent thermal stability,mechanical per-formance,and flame retardancy.Furthermore,employing Foygel’s theory elucidated the impact of filler arrangement on thermal conductivity mechanisms and the actual application of 5 G device chips and LED lamps emphasizing the potential of these thermally conductive films in thermal management appli-cations.This investigation contributes valuable design concepts and foundations for the development of anisotropic thermally conductive composites suitable for electron thermal management.
基金supported by the National Natural Science Foundation of China(62073267,61903305)the Fundamental Research Funds for the Central Universities(HXGJXM202214).
文摘The lack of systematic and scientific top-level arrangement in the field of civil aircraft flight test leads to the problems of long duration and high cost.Based on the flight test activity,mathematical models of flight test duration and cost are established to set up the framework of flight test process.The top-level arrangement for flight test is optimized by multi-objective algorithm to reduce the duration and cost of flight test.In order to verify the necessity and validity of the mathematical models and the optimization algorithm of top-level arrangement,real flight test data is used to make an example calculation.Results show that the multi-objective optimization results of the top-level flight arrangement are better than the initial arrangement data,which can shorten the duration,reduce the cost,and improve the efficiency of flight test.
基金funded by the Natural Science Foundation of China[U20A20292]Shandong Province Science andTechnology SMES InnovationAbility Improvement Project[2023TSGC0005]China Postdoctoral Science Foundation[2024M752697].
文摘In nature,cavitation bubbles typically appear in clusters,engaging in interactions that create a variety of dynamicmotion patterns.To better understand the behavior ofmultiple bubble collapses and the mechanisms of interbubble interaction,this study employs molecular dynamics simulation combined with a coarse-grained force field.By focusing on collapsemorphology,local density,and pressure,it elucidates how the number and arrangement of bubbles influence the collapse process.The mechanisms behind inter-bubble interactions are also considered.The findings indicate that the collapse speed of unbounded bubbles located in lateral regions is greater than that of the bubbles in the center.Moreover,it is shown that asymmetrical bubble distributions lead to a shorter collapse time overall.
基金the financial support from the National Natural Science Foundation of China(No.52225208 and 51802131)the Training Program for academic and technical leaders in major disciplines of Jiangxi Province-Young Talents(No.20212BCJ23021)the Natural Science Foundation of Jiangxi Province,China(No.20232BAB204020).
文摘1T-MoS_(2)nanosheets,with metallic conductivity and high capacity,hold great potential for lithium-ion capacitors(LICs),but suffer from sluggish reaction kinetics due to dense stacking.Herein,1T-MoS_(2)nanosheets with enlarged interlayer spacing,vertically bonded to reduced graphene oxide(rGO)(1T-MoS_(2)/rGO),were designed using a hydrothermal-assisted dispersion and intercalation strategy.The active nitrogen species derived from N,N-dimethylformamide(DMF)not only bridge the rGO and MoS_(2)through strong Mo-N-C bonds to promote the formation of dispersed MoS_(2)nanosheets,but also intercalate into the MoS_(2)structure,further enlarging the interlayer spacing.This unique structure synergistically enhances meso-and microscale mass transfer outside and inside of the few-layered nanosheets,significantly improving electrochemical reaction kinetics and reducing the kinetic mismatch between the anode and cathode.Consequently,the resulting 1T-MoS_(2)/rGO achieves a capacity of 500 mAh g^(-1)after 500 cycles at 5 A g^(-1)and a high rate performance of 587 mAh g^(-1)at a high rate of 10 A g^(-1).Moreover,the assembled 3D vertical 1T-MoS_(2)/rGO//AC LIC delivers a high energy density of 100.3 Wh kg^(-1)at a power density of1.0 kW kg^(-1),and long cycle stability with capacity retention as high as 91.02%after 5000 cycles at 2 A g^(-1).This work provides a generalizable strategy for engineering two-dimensional material-based electrodes,offering new insights into high-performance energy storage systems.
基金supported by the National Natural Science Foundation of China(No.42277256)the Natural Science Foundation of Hunan Province(No.2022JJ30710)+1 种基金Hunan Province Environmental Protection Research Program(No.HBKT-2021014)Guangdong Province Dabaoshan Mining Co.Ltd Technology Program(Semi-industrial test of 200T/time low-grade copper ore bio-heap leaching).
文摘The migration and transformation of hexavalent chromium(Cr(VI))in the environment are regulated by pyrite(FeS2).However,variations in pyrite crystal facets influence the adsorption behavior and electron transfer between pyrite and Cr(VI),thereby impacting the Cr(VI)reduction performance.Herein,two naturally common facets of pyritewere synthesized hydrothermally to investigate the facet-dependent mechanisms of Cr(VI)reduction.The experimental results revealed that the{111}facet exhibited approximately 1.30–1.50 times higher efficiency in Cr(VI)reduction compared to the{100}facet.Surface analyses and electrochemical results indicated that{111}facet displayed a higher iron-sulfur oxidation level,which was affected by its superior electrochemical properties during the reaction with Cr(VI).Density functional theory(DFT)calculations demonstrated that the narrower band gap and lower work function on{111}facet were more favorable for the electron transfer between Fe(II)and Cr(VI).Furthermore,different adsorption configurations were observed on{100}and{111}surfaces due to the unique arrangements of Fe and S atoms.Specifically,O atoms in Cr_(2)O_(7)^(2−)directly bound with the S sites on{100}but the Fe sites on{111}.According to the density of states(DOS),the Fe site had better reactivity than the S site in the reaction,which appeared to be related to the fracture of S-S bonds.Additionally,the adsorption configuration of Cr_(2)O_(7)^(2−)on{111}surface showed a stronger adsorption energy and a more stable coordination mode,favoring subsequent Cr(VI)reduction process.These findings provide an in-depth analysis of facet-dependent mechanisms underlying Cr(VI)reduction behavior,offering new insights into studying environmental interactions between heavy metals and natural minerals.
