It is significant to develop a robot hand with high rigidity by a 6-DOF parallel manipulator（PM）.However,the existing6-DOF PMs include spherical joint which has less capability of pulling force bearing,less rotation...It is significant to develop a robot hand with high rigidity by a 6-DOF parallel manipulator（PM）.However,the existing6-DOF PMs include spherical joint which has less capability of pulling force bearing,less rotation range and lower precision under alternately heavy loads.A novel 6-DOF PM with three planar limbs and equipped with three fingers is proposed and its kinematics and statics are analyzed systematically.A 3-dimension simulation mechanism of the proposed manipulator is constructed and its structure characteristics is analyzed.The kinematics formulae for solving the displacement,velocity,acceleration of the platform,the active legs and the fingers are established.The statics formulae are derived for solving the active forces of PM and the finger mechanisms.An analytic example is given for solving the kinematics and statics of proposed manipulator and the analytic solved results are verified by the simulation mechanism.It is proved from the error analysis of analytic solutions and simulation solutions that the derived analytic formulae are correct and provide the theoretical and technical foundations for its manufacturing,control and application.展开更多
Objective To study mechanics characteristics of two cooperative reconfigurable planetary robots when they get across an obstacle, and to find out the relationship between the maximum height of a stair with the configu...Objective To study mechanics characteristics of two cooperative reconfigurable planetary robots when they get across an obstacle, and to find out the relationship between the maximum height of a stair with the configuration of the two-robot, and to find some restrictions of kinematics for the cooperation. Methods Multirobot cooperation theory is used in the whole study process. Inverse kinematics of the robot is used to form a desired configuration in the cooperation process. Static equations are established to analyze the relations between the friction factor, the configuration of robots and the maximum height of a stair. Kinematics analysis is used to find the restrictions of the two collaborative robots in position, velocity and acceleration. Results 3D simulation shows that the two cooperative robots can climb up a stair under the condition of a certain height and a certain friction factor between robot wheel and the surface of the stair. Following the restrictions of kinematics, the climbing mission is fulfilled successfully and smoothly. Conclusion The maximum height of a stair, which the two cooperative robots can climb up, is involved in the configuration of robots, friction factor between the stair and the robots. The most strict restriction of the friction factor does not appear in the horizontal position. In any case, the maximum height is smaller than half of the distance between the centroid of robot1 with the centroid of robot2. However, the height can be higher than the radius of one robot wheel, which profit from the collaboration.展开更多
Hydrogen （H） defect interactions have been investigated by molecular statics sim- ulations in tungsten （W）, including H-H interactions and interactions between H and W self- interstitial atoms. The interactions be...Hydrogen （H） defect interactions have been investigated by molecular statics sim- ulations in tungsten （W）, including H-H interactions and interactions between H and W self- interstitial atoms. The interactions between H and small H-vacancy clusters are also demonstrated; the binding energies of an H, a vacancy and a self-interstitial W to an H-vacancy cluster depend on the H-to-vacancy ratio. We conclude that H bubble formation needs a high concentration of H in W for the H bubble nucleation and growth, which are also governed by the H-to-vacancy ratio of the cluster. The vacancy first combines with H atoms and a cluster forms, then the H-vacancy cluster goes through the whole process of vacancy capture, H capture, and vacancy capture again, and as a result the H-vacancy cluster grows larger and larger. Finally, the H bubble forms.展开更多
This work presents a new science called atomic and molecular reaction statics (AMRS). There are four parts for AMRS, i.e. the group theoretical derivation of mo- lecular electronic states, the principle of microscopic...This work presents a new science called atomic and molecular reaction statics (AMRS). There are four parts for AMRS, i.e. the group theoretical derivation of mo- lecular electronic states, the principle of microscopic reversibility, the principle of microscopic transitivity and the optimum energy process rule. AMRS has been developed for about twenty years.展开更多
The analogy between the human body and architectural structures dates all the way back to ancient times and has significantly shaped the design of buildings and structures.The article examines the body’s historical i...The analogy between the human body and architectural structures dates all the way back to ancient times and has significantly shaped the design of buildings and structures.The article examines the body’s historical influence on how structures are perceived and designed,demonstrating how the body shapes the"technical truth"dimension of structural design while oblivious to the importance of an"artistic truth"or perceptual dimension.This article aims to connect recent neuroscience findings and their implications for structural design through graphic statics and its design methods.Finally,this article proposes an equilibrium-based structural design approach for designing embodied structures based on graphic statics.展开更多
Starting from the foundational static traits underlying the growth and development of flue-cured tobacco, this research conducts a systematic examination of the phenomena and theoretical principles associated with env...Starting from the foundational static traits underlying the growth and development of flue-cured tobacco, this research conducts a systematic examination of the phenomena and theoretical principles associated with environment-driven adaptive changes during its cultivation. It was found that environmental variables-including temperature, light, and moisture-elicit directional shifts in static traits ( e.g. , chemical composition, morphological architecture, and leaf tissue structure) toward enhanced environmental adaptation, characterized by graduality, juvenility, similarity, and correlativity. Upon alterations in ambient conditions, flue-cured tobacco modulates its static traits through integrated physical, chemical, and biological-genetic mechanisms, aiming to optimize resource utilization, mitigate environmental constraints, and preserve internal homeostasis alongside metabolic balance. The investigation further reveals that the adaptive scope of flue-cured tobacco to field environments is malleable and can be extended and elevated via adaptive conditioning commencing at the juvenile stage. In addition, the adaptive alignment between static traits and environmental parameters exerts a substantial impact on the plant s growth dynamics, yield performance, and quality attributes. Beyond its relevance to flue-cured tobacco, the proposed theory offers a meaningful framework for elucidating the pervasive adaptive strategies employed by plants and broader biological systems in response to environmental contingencies.展开更多
Thermoelectric (TE) materials enable precise, noiseless, and moving-part-free waste heat recovery and solid-state refrigeration through the Seebeck and Peltier effects [1–3]. The efficiency of TE materials is typical...Thermoelectric (TE) materials enable precise, noiseless, and moving-part-free waste heat recovery and solid-state refrigeration through the Seebeck and Peltier effects [1–3]. The efficiency of TE materials is typically evaluated by a dimensionless figure of merit (ZT = S2σT/(κe+ κl)), which depends on the delicate interplay among the electrical conductivity (σ), Seebeck coefficient (S), lattice thermal conductivity (κl), and electronic thermal conductivity (κe) [4].展开更多
The accumulation and circulation of carbon and hydrogen contribute to the chemical evolution of ice giant planets.Species separation and diamond precipitation have been reported in carbon-hydrogen systems and have bee...The accumulation and circulation of carbon and hydrogen contribute to the chemical evolution of ice giant planets.Species separation and diamond precipitation have been reported in carbon-hydrogen systems and have been verified by static and shock compression experiments.Nevertheless,the dynamic formation processes underlying these phenomena remain insufficiently understood.In combination with a deep learning model,we demonstrate that diamonds form through a three-step process involving dissociation,species separation,and nucleation processes.Under shock conditions of 125 GPa and 4590 K,hydrocarbons decompose to give hydrogen and low-molecular-weight alkanes(CH_(4) and C_(2)H_(6)),which escape from the carbon chains,resulting in C/H species separation.The remaining carbon atoms without C-H bonds accumulate and nucleate to form diamond crystals.The process of diamond growth is associated with a critical nucleus size at which the dynamic energy barrier plays a key role.These dynamic processes of diamond formation provide insight into the establishment of a model for the evolution of ice giant planets.展开更多
This paper presents the variational physics-informed neural network(VPINN)as an effective tool for static structural analyses.One key innovation includes the construction of the neural network solution as an admissibl...This paper presents the variational physics-informed neural network(VPINN)as an effective tool for static structural analyses.One key innovation includes the construction of the neural network solution as an admissible function of the boundary-value problem(BVP),which satisfies all geometrical boundary conditions.We then prove that the admissible neural network solution also satisfies natural boundary conditions,and therefore all boundary conditions,when the stationarity condition of the variational principle is met.Numerical examples are presented to show the advantages and effectiveness of the VPINN in comparison with the physics-informed neural network(PINN).Another contribution of the work is the introduction of Gaussian approximation of the Dirac delta function,which significantly enhances the ability of neural networks to handle singularities,as demonstrated by the examples with concentrated support conditions and loadings.It is hoped that these structural examples are so convincing that engineers would adopt the VPINN method in their structural design practice.展开更多
Conventional rolled Mg-Al alloy sheets typically exhibit strong basal textures that remain and may even strengthen after recrystallization annealing due to the preferential growth of basal-oriented grains,resulting in...Conventional rolled Mg-Al alloy sheets typically exhibit strong basal textures that remain and may even strengthen after recrystallization annealing due to the preferential growth of basal-oriented grains,resulting in poor formability at room temperature.Therefore,the knowledge of recrystallization and grain growth is critical for modifying textures of Mg-Al alloy sheets.The static recrystallization and texture evolution in a cold-rolled dilute Mg-1Al(wt.%)alloy during various annealed temperatures ranging from 300℃ to 450℃,have been investigated using the quasi in-situ electron backscatter diffraction(EBSD)method.The as-rolled Mg-1Al alloy shows a dominant basal texture,which weakens and broadens in the rolling direction(RD)during the subsequent annealing,accompanied by the formation of{1010}texture component.Particularly,the {1010} texture component is more pronounced after annealing at high temperatures.The quasi in-situ EBSD results show that recrystallized grains are mainly induced by shear bands,which exhibit a wide spectrum of orientations with c-axis tilt angles ranging 20°-45°from the normal direction(ND).Orientations of shear band-induced recrystallized grains are retained during the entire recrystallization process,resulting in a reduction in the texture intensity.Moreover,recrystallized grains belonging to the {1010}texture component grow preferentially compared to those with other orientations,which is attributed to low energy grain boundaries,especially grain boundaries with∼30°misorientation angles.Furthermore,the high temperature annealing facilitates the rapid growth of grain boundaries having a 30°misorientation angle,leading to the occurrence of distinct {1010} texture after annealing at 450℃ for 1 h.The results provide insights for texture modification of rare earth-free low-alloyed Mg alloys by controlling annealing parameters.展开更多
Main cable displacement-controlled devices(DCDs)are key components for coordinating the vertical deformation of the main cable and main girder in the side span of continuous suspension bridges.To reveal the mechanical...Main cable displacement-controlled devices(DCDs)are key components for coordinating the vertical deformation of the main cable and main girder in the side span of continuous suspension bridges.To reveal the mechanical action mechanisms of DCD on bridge structures,a three-span continuous suspension bridge was taken as the engineering background in this study.The influence of different forms of DCD on the internal force and displacement of the components in the side span of the bridge and the structural dynamic characteristics were explored through numerical simulations.The results showed that the lack of DCD caused the main cable and main girder to have large vertical displacements.The stresses of other components were redistributed,and the safety factor of the suspenders at the side span was greatly reduced.The setting of DCD improved the vertical stiffness of the structure.The rigid DCD had larger internal forces,but its control effect on the internal forces at the side span was slightly better than that of the flexible DCD.Both forms of DCD effectively coordinated the deformation of the main cable and main girder and the stress distribution of components in the side span area.The choice of DCD form depends on the topographic factors of bridge sites and the design requirements of related components at the side span.展开更多
Flexoelectricity refers to the link between electrical polarization and strain gradient fields in piezoelectric materials,particularly at the nano-scale.The present investigation aims to comprehensively focus on the s...Flexoelectricity refers to the link between electrical polarization and strain gradient fields in piezoelectric materials,particularly at the nano-scale.The present investigation aims to comprehensively focus on the static bending analysis of a piezoelectric sandwich functionally graded porous(FGP)double-curved shallow nanoshell based on the flexoelectric effect and nonlocal strain gradient theory.Two coefficients that reduce or increase the stiffness of the nanoshell,including nonlocal and length-scale parameters,are considered to change along the nanoshell thickness direction,and three different porosity rules are novel points in this study.The nanoshell structure is placed on a Pasternak elastic foundation and is made up of three separate layers of material.The outermost layers consist of piezoelectric smart material with flexoelectric effects,while the core layer is composed of FGP material.Hamilton’s principle was used in conjunction with a unique refined higher-order shear deformation theory to derive general equilibrium equations that provide more precise outcomes.The Navier and Galerkin-Vlasov methodology is used to get the static bending characteristics of nanoshells that have various boundary conditions.The program’s correctness is assessed by comparison with published dependable findings in specific instances of the model described in the article.In addition,the influence of parameters such as flexoelectric effect,nonlocal and length scale parameters,elastic foundation stiffness coefficient,porosity coefficient,and boundary conditions on the static bending response of the nanoshell is detected and comprehensively studied.The findings of this study have practical implications for the efficient design and control of comparable systems,such as micro-electromechanical and nano-electromechanical devices.展开更多
In recent decades,control performance monitoring(CPM)has experienced remarkable progress in research and industrial applications.While CPM research has been investigated using various benchmarks,the historical data be...In recent decades,control performance monitoring(CPM)has experienced remarkable progress in research and industrial applications.While CPM research has been investigated using various benchmarks,the historical data benchmark(HIS)has garnered the most attention due to its practicality and effectiveness.However,existing CPM reviews usually focus on the theoretical benchmark,and there is a lack of an in-depth review that thoroughly explores HIS-based methods.In this article,a comprehensive overview of HIS-based CPM is provided.First,we provide a novel static-dynamic perspective on data-level manifestations of control performance underlying typical controller capacities including regulation and servo:static and dynamic properties.The static property portrays time-independent variability in system output,and the dynamic property describes temporal behavior driven by closed-loop feedback.Accordingly,existing HIS-based CPM approaches and their intrinsic motivations are classified and analyzed from these two perspectives.Specifically,two mainstream solutions for CPM methods are summarized,including static analysis and dynamic analysis,which match data-driven techniques with actual controlling behavior.Furthermore,this paper also points out various opportunities and challenges faced in CPM for modern industry and provides promising directions in the context of artificial intelligence for inspiring future research.展开更多
Herein,a one-pot chemical reduction method was reported to prepare folic acid(FA)-stabilized silver nanoclusters(FA@Ag NCs),in which FA,hydrazine hydrate,and silver nitrate were used as capping agent,reducing agent,an...Herein,a one-pot chemical reduction method was reported to prepare folic acid(FA)-stabilized silver nanoclusters(FA@Ag NCs),in which FA,hydrazine hydrate,and silver nitrate were used as capping agent,reducing agent,and precursor,respectively.Several technologies were employed to investigate the structures and optical properties of FA@Ag NCs,including transmission electron microscopy(TEM),X-ray photoelectron spectrometer(XPS),Fourier transform infrared spectrometer(FTIR),X-ray diffractometer(XRD),fluorescence spectrometer,and ultraviolet visible absorption spectrometer.FA@Ag NCs were suggested to be highly dispersed and spherical with a size of around 2.8 nm.Moreover,the maximum excitation and emission wavelengths of FA@Ag NCs were 370 and 447 nm,respectively.Under the optimal detection conditions,FA@Ag NCs could be used to effectively detect malachite green with the linear detection range of 0.5-200μmol·L^(-1).The detection limit was 0.084μmol·L^(-1).The fluorescence-quenching mechanism was ascribed to the static quenching.The detection system based on FA@AgNCs was successfully used for the detection of malachite green in actual samples with good accuracy and reproducibility.展开更多
Due to their superior properties, the interest in nanostructures is increasing today in engineering. This study presents a new two-noded curved finite element for analyzing the in-plane static behaviors of curved nano...Due to their superior properties, the interest in nanostructures is increasing today in engineering. This study presents a new two-noded curved finite element for analyzing the in-plane static behaviors of curved nanobeams. Opposite to traditional curved finite elements developed by using approximate interpolation functions, the proposed curved finite element is developed by using exact analytical solutions. Although this approach was first introduced for analyzing the mechanical behaviors of macro-scale curved beams by adopting the local theory of elasticity, the exact analytical expressions used in this study were obtained from the solutions of governing equations that were expressed via the differential form of the nonlocal theory of elasticity. Therefore, the effects of shear strain and axial extension included in the analytical formulation are also inherited by the curved finite element developed here. The rigidity matrix and the consistent force vector are developed for a circular finite element. To demonstrate the applicability of the method, static analyses of various curved nanobeams subjected to different boundary conditions and loading scenarios are performed, and the obtained results are compared with the exact analytical ones. The presented study provides an accurate and low computational cost method for researchers to investigate the in-plane static behavior of curved nanobeams.展开更多
Background The rapid development of intensive layer breeding has intensified odor pollution that must be paid attention to for the green transformation of the industry. This study used Jingfen No.6 laying hens as the ...Background The rapid development of intensive layer breeding has intensified odor pollution that must be paid attention to for the green transformation of the industry. This study used Jingfen No.6 laying hens as the model to systematically evaluate the regulatory effect of compound microalgal powder(Chlorella vulgaris:Spirulina platensis:Haematococcus pluvialis = 3:1:1, 1:3:1, 1:1:3) on ammonia(NH3) emissions from laying hen manure.Results Through analysis of the static NH3production in manure, it was found that the NH3emissions within 24 h in the experimental group with 0.50% compound microalgal powder added were reduced to 6.27–16.84 mg(vs. control: 28.29 mg), achieving a 40.47%–77.84% reduction. GC/MS and 16S rRNA sequencing analyses indicated that the compound microalgal powder intervened in the remodeling of the microbial community and nitrogen metabolism network in manure, driving the transformation from inorganic nitrogen to organic nitrogen, mitigated the proliferation of NH3-producing bacteria(such as Escherichia coli, Klebsiella pneumoniae, Kurthia, and Proteus), and increased the abundance of acid-producing bacteria(such as Leuconostocaceae and Lactobacillaceae). The Spirulina platensis powder group had the best emission reduction effect(reduced by 77.84%), and its mechanism was closely related to the mitigation of Gram-negative bacteria activity by phycocyanin and increased synthesis of aromatic compounds, such as 2,3,5-trimethyl-6-ethylpyrazine.Conclusions This study revealed the mechanism by which the compound microalgal powder reduces NH3emissions by regulating the proliferation of acid-producing bacteria, reshaping the nitrogen metabolism network, and mitigating the activity of NH3-producing bacteria, while providing theoretical and data support for the development of environmentally friendly feed.展开更多
Rotary steering systems(RSSs)have been increasingly used to develop horizontal wells.A static push-the-bit RSS uses three hydraulic modules with varying degrees of expansion and contraction to achieve changes in the p...Rotary steering systems(RSSs)have been increasingly used to develop horizontal wells.A static push-the-bit RSS uses three hydraulic modules with varying degrees of expansion and contraction to achieve changes in the pushing force acting on the wellbore in different sizes and directions within a circular range,ultimately allowing the wellbore trajectory to be drilled in a predetermined direction.By analyzing its mathematical principles and the actual characteristics of the instrument,a vector force closed-loop control method,including steering and holding modes,was designed.The adjustment criteria for the three hydraulic modules are determined to achieve rapid adjustment of the vector force.The theoretical feasibility of the developed method was verified by comparing its results with the on-site application data of an imported rotary guidance system.展开更多
Understanding the reinforcement effect of the newly developed prestressed reinforcement components(PRCs)(a system composed of prestressed steel bars(PSBs),protective sleeves,lateral pressure plates(LPPs),and anchoring...Understanding the reinforcement effect of the newly developed prestressed reinforcement components(PRCs)(a system composed of prestressed steel bars(PSBs),protective sleeves,lateral pressure plates(LPPs),and anchoring elements)is technically significant for the rational design of prestressed subgrade.A three-dimensional finite element model was established and verified based on a novel static model test and utilized to systematically analyze the influence of prestress levels and reinforcement modes on the reinforcement effect of the subgrade.The results show that the PRCs provide additional confining pressure to the subgrade through the diffusion effect of the prestress,which can therefore effectively improve the service performance of the subgrade.Compared to the unreinforced conventional subgrades,the settlements of prestressreinforced subgrades are reduced.The settlement attenuation rate(Rs)near the LPPs is larger than that at the subgrade center,and increasing the prestress positively contributes to the stability of the subgrade structure.In the multi-row reinforcement mode,the reinforcement effect of PRCs can extend from the reinforced area to the unreinforced area.In addition,as the horizontal distance from the LPPs increases,the additional confining pressure converted by the PSBs and LPPs gradually diminishes when spreading to the core load bearing area of the subgrade,resulting in a decrease in the Rs.Under the singlerow reinforcement mode,PRCs can be strategically arranged according to the local areas where subgrade defects readily occurred or observed,to obtain the desired reinforcement effect.Moreover,excessive prestress should not be applied near the subgrade shoulder line to avoid the shear failure of the subgrade shoulder.PRCs can be flexibly used for preventing and treating various subgrade defects of newly constructed or existing railway lines,achieving targeted and classified prevention,and effectively improving the bearing performance and deformation resistance of the subgrade.The research results are instructive for further elucidating the prestress reinforcement effect of PRCs on railway subgrades.展开更多
The accuracy of the full-scale aircraft static tests is greatly influenced by the aircraft attitude.This paper proposes an aircraft attitude optimization method based on the characteristics of the test.The aim is to a...The accuracy of the full-scale aircraft static tests is greatly influenced by the aircraft attitude.This paper proposes an aircraft attitude optimization method based on the characteristics of the test.The aim is to address three typical problems of ttitude control in the full-scale aircraft static tests:(1)The coupling of rigid-body displacement and elastic deformation after large deformation,(2)the difficulty of characterizing the aircraft attitude by measurable structure,and(3)the insufficient adaptability of the center of gravity reference to complex loading conditions.The methodology involves the establishment of two observation coordinate systems,a ground coordinate system and an airframe coordinate system,and two deformation states,before and after airframe deformation.A subsequent analysis of the parameter changes of these two states under different coordinate systems is then undertaken,with the objective being to identify the key parameters affecting the attitude control accuracy of large deformation aircraft.Three optimization objective functions are established according to the test loading characteristics and the purpose of the test:(1)To minimize the full-scale aircraft loading angle error,(2)to minimize the full-scale aircraft loading additional load,and(3)to minimize the full-scale aircraft loading wing root additional bending moment.The optimization calculation results are obtained by using the particle swarm optimization algorithm,and the typical full-scale aircraft static test load condition of large passenger aircraft is taken as an example.The analysis of the results demonstrates that by customizing the measurable structure of the aircraft as the observation point for the aircraft attitude,and by obtaining the translational and rotational control parameters of the observation point during the test based on the optimization objective function,the results are reasonable,and the project can be implemented and used to control the aircraft's attitude more accurately in complex force test conditions.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51175447)Key Planned Project of Hebei Province,China(Grant No.11962127D)
文摘It is significant to develop a robot hand with high rigidity by a 6-DOF parallel manipulator（PM）.However,the existing6-DOF PMs include spherical joint which has less capability of pulling force bearing,less rotation range and lower precision under alternately heavy loads.A novel 6-DOF PM with three planar limbs and equipped with three fingers is proposed and its kinematics and statics are analyzed systematically.A 3-dimension simulation mechanism of the proposed manipulator is constructed and its structure characteristics is analyzed.The kinematics formulae for solving the displacement,velocity,acceleration of the platform,the active legs and the fingers are established.The statics formulae are derived for solving the active forces of PM and the finger mechanisms.An analytic example is given for solving the kinematics and statics of proposed manipulator and the analytic solved results are verified by the simulation mechanism.It is proved from the error analysis of analytic solutions and simulation solutions that the derived analytic formulae are correct and provide the theoretical and technical foundations for its manufacturing,control and application.
基金This workis supported in part by the Hi-tech Research and Development Programof China (2002AA422130) .
文摘Objective To study mechanics characteristics of two cooperative reconfigurable planetary robots when they get across an obstacle, and to find out the relationship between the maximum height of a stair with the configuration of the two-robot, and to find some restrictions of kinematics for the cooperation. Methods Multirobot cooperation theory is used in the whole study process. Inverse kinematics of the robot is used to form a desired configuration in the cooperation process. Static equations are established to analyze the relations between the friction factor, the configuration of robots and the maximum height of a stair. Kinematics analysis is used to find the restrictions of the two collaborative robots in position, velocity and acceleration. Results 3D simulation shows that the two cooperative robots can climb up a stair under the condition of a certain height and a certain friction factor between robot wheel and the surface of the stair. Following the restrictions of kinematics, the climbing mission is fulfilled successfully and smoothly. Conclusion The maximum height of a stair, which the two cooperative robots can climb up, is involved in the configuration of robots, friction factor between the stair and the robots. The most strict restriction of the friction factor does not appear in the horizontal position. In any case, the maximum height is smaller than half of the distance between the centroid of robot1 with the centroid of robot2. However, the height can be higher than the radius of one robot wheel, which profit from the collaboration.
基金supported by National Natural Science Foundation of China(Nos.51171008 and 11405201)the National Magnetic Confinement Fusion Program of China(No.2013GB1090)
文摘Hydrogen （H） defect interactions have been investigated by molecular statics sim- ulations in tungsten （W）, including H-H interactions and interactions between H and W self- interstitial atoms. The interactions between H and small H-vacancy clusters are also demonstrated; the binding energies of an H, a vacancy and a self-interstitial W to an H-vacancy cluster depend on the H-to-vacancy ratio. We conclude that H bubble formation needs a high concentration of H in W for the H bubble nucleation and growth, which are also governed by the H-to-vacancy ratio of the cluster. The vacancy first combines with H atoms and a cluster forms, then the H-vacancy cluster goes through the whole process of vacancy capture, H capture, and vacancy capture again, and as a result the H-vacancy cluster grows larger and larger. Finally, the H bubble forms.
文摘This work presents a new science called atomic and molecular reaction statics (AMRS). There are four parts for AMRS, i.e. the group theoretical derivation of mo- lecular electronic states, the principle of microscopic reversibility, the principle of microscopic transitivity and the optimum energy process rule. AMRS has been developed for about twenty years.
基金This study was funded by the China Scholarship Council(Grant No.202008170012).
文摘The analogy between the human body and architectural structures dates all the way back to ancient times and has significantly shaped the design of buildings and structures.The article examines the body’s historical influence on how structures are perceived and designed,demonstrating how the body shapes the"technical truth"dimension of structural design while oblivious to the importance of an"artistic truth"or perceptual dimension.This article aims to connect recent neuroscience findings and their implications for structural design through graphic statics and its design methods.Finally,this article proposes an equilibrium-based structural design approach for designing embodied structures based on graphic statics.
基金Supported by Changsha Tobacco Company Science and Technology Project(2020-2024A04).
文摘Starting from the foundational static traits underlying the growth and development of flue-cured tobacco, this research conducts a systematic examination of the phenomena and theoretical principles associated with environment-driven adaptive changes during its cultivation. It was found that environmental variables-including temperature, light, and moisture-elicit directional shifts in static traits ( e.g. , chemical composition, morphological architecture, and leaf tissue structure) toward enhanced environmental adaptation, characterized by graduality, juvenility, similarity, and correlativity. Upon alterations in ambient conditions, flue-cured tobacco modulates its static traits through integrated physical, chemical, and biological-genetic mechanisms, aiming to optimize resource utilization, mitigate environmental constraints, and preserve internal homeostasis alongside metabolic balance. The investigation further reveals that the adaptive scope of flue-cured tobacco to field environments is malleable and can be extended and elevated via adaptive conditioning commencing at the juvenile stage. In addition, the adaptive alignment between static traits and environmental parameters exerts a substantial impact on the plant s growth dynamics, yield performance, and quality attributes. Beyond its relevance to flue-cured tobacco, the proposed theory offers a meaningful framework for elucidating the pervasive adaptive strategies employed by plants and broader biological systems in response to environmental contingencies.
基金supports from the Department of Education of Liaoning Province (LJ242510147006)
文摘Thermoelectric (TE) materials enable precise, noiseless, and moving-part-free waste heat recovery and solid-state refrigeration through the Seebeck and Peltier effects [1–3]. The efficiency of TE materials is typically evaluated by a dimensionless figure of merit (ZT = S2σT/(κe+ κl)), which depends on the delicate interplay among the electrical conductivity (σ), Seebeck coefficient (S), lattice thermal conductivity (κl), and electronic thermal conductivity (κe) [4].
基金supported by the National Natural Science Foundation of China(Grant Nos.12534013,12047561,and 12104507)the Science and Technology Innovation Program of Hunan Province(Grant Nos.2025ZYJ001 and 2021RC4026)the National University of Defense Technology Research Fund Project.
文摘The accumulation and circulation of carbon and hydrogen contribute to the chemical evolution of ice giant planets.Species separation and diamond precipitation have been reported in carbon-hydrogen systems and have been verified by static and shock compression experiments.Nevertheless,the dynamic formation processes underlying these phenomena remain insufficiently understood.In combination with a deep learning model,we demonstrate that diamonds form through a three-step process involving dissociation,species separation,and nucleation processes.Under shock conditions of 125 GPa and 4590 K,hydrocarbons decompose to give hydrogen and low-molecular-weight alkanes(CH_(4) and C_(2)H_(6)),which escape from the carbon chains,resulting in C/H species separation.The remaining carbon atoms without C-H bonds accumulate and nucleate to form diamond crystals.The process of diamond growth is associated with a critical nucleus size at which the dynamic energy barrier plays a key role.These dynamic processes of diamond formation provide insight into the establishment of a model for the evolution of ice giant planets.
基金supported by the National Natural Science Foundation of China(Nos.12072118 and12372029)。
文摘This paper presents the variational physics-informed neural network(VPINN)as an effective tool for static structural analyses.One key innovation includes the construction of the neural network solution as an admissible function of the boundary-value problem(BVP),which satisfies all geometrical boundary conditions.We then prove that the admissible neural network solution also satisfies natural boundary conditions,and therefore all boundary conditions,when the stationarity condition of the variational principle is met.Numerical examples are presented to show the advantages and effectiveness of the VPINN in comparison with the physics-informed neural network(PINN).Another contribution of the work is the introduction of Gaussian approximation of the Dirac delta function,which significantly enhances the ability of neural networks to handle singularities,as demonstrated by the examples with concentrated support conditions and loadings.It is hoped that these structural examples are so convincing that engineers would adopt the VPINN method in their structural design practice.
基金by National Natural Science Foundation of China(Nos.52271103,52334010 and 52271031)Jilin Scientific and Technological Development Program(Nos.20220301026GX,20210201115GX and 20210301041GX).
文摘Conventional rolled Mg-Al alloy sheets typically exhibit strong basal textures that remain and may even strengthen after recrystallization annealing due to the preferential growth of basal-oriented grains,resulting in poor formability at room temperature.Therefore,the knowledge of recrystallization and grain growth is critical for modifying textures of Mg-Al alloy sheets.The static recrystallization and texture evolution in a cold-rolled dilute Mg-1Al(wt.%)alloy during various annealed temperatures ranging from 300℃ to 450℃,have been investigated using the quasi in-situ electron backscatter diffraction(EBSD)method.The as-rolled Mg-1Al alloy shows a dominant basal texture,which weakens and broadens in the rolling direction(RD)during the subsequent annealing,accompanied by the formation of{1010}texture component.Particularly,the {1010} texture component is more pronounced after annealing at high temperatures.The quasi in-situ EBSD results show that recrystallized grains are mainly induced by shear bands,which exhibit a wide spectrum of orientations with c-axis tilt angles ranging 20°-45°from the normal direction(ND).Orientations of shear band-induced recrystallized grains are retained during the entire recrystallization process,resulting in a reduction in the texture intensity.Moreover,recrystallized grains belonging to the {1010}texture component grow preferentially compared to those with other orientations,which is attributed to low energy grain boundaries,especially grain boundaries with∼30°misorientation angles.Furthermore,the high temperature annealing facilitates the rapid growth of grain boundaries having a 30°misorientation angle,leading to the occurrence of distinct {1010} texture after annealing at 450℃ for 1 h.The results provide insights for texture modification of rare earth-free low-alloyed Mg alloys by controlling annealing parameters.
基金The National Natural Science Foundation of China(No.52338011)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX23_0067).
文摘Main cable displacement-controlled devices(DCDs)are key components for coordinating the vertical deformation of the main cable and main girder in the side span of continuous suspension bridges.To reveal the mechanical action mechanisms of DCD on bridge structures,a three-span continuous suspension bridge was taken as the engineering background in this study.The influence of different forms of DCD on the internal force and displacement of the components in the side span of the bridge and the structural dynamic characteristics were explored through numerical simulations.The results showed that the lack of DCD caused the main cable and main girder to have large vertical displacements.The stresses of other components were redistributed,and the safety factor of the suspenders at the side span was greatly reduced.The setting of DCD improved the vertical stiffness of the structure.The rigid DCD had larger internal forces,but its control effect on the internal forces at the side span was slightly better than that of the flexible DCD.Both forms of DCD effectively coordinated the deformation of the main cable and main girder and the stress distribution of components in the side span area.The choice of DCD form depends on the topographic factors of bridge sites and the design requirements of related components at the side span.
基金This work was supported by the Le Quy Don Technical University Research Fund(Grant No.23.1.11).
文摘Flexoelectricity refers to the link between electrical polarization and strain gradient fields in piezoelectric materials,particularly at the nano-scale.The present investigation aims to comprehensively focus on the static bending analysis of a piezoelectric sandwich functionally graded porous(FGP)double-curved shallow nanoshell based on the flexoelectric effect and nonlocal strain gradient theory.Two coefficients that reduce or increase the stiffness of the nanoshell,including nonlocal and length-scale parameters,are considered to change along the nanoshell thickness direction,and three different porosity rules are novel points in this study.The nanoshell structure is placed on a Pasternak elastic foundation and is made up of three separate layers of material.The outermost layers consist of piezoelectric smart material with flexoelectric effects,while the core layer is composed of FGP material.Hamilton’s principle was used in conjunction with a unique refined higher-order shear deformation theory to derive general equilibrium equations that provide more precise outcomes.The Navier and Galerkin-Vlasov methodology is used to get the static bending characteristics of nanoshells that have various boundary conditions.The program’s correctness is assessed by comparison with published dependable findings in specific instances of the model described in the article.In addition,the influence of parameters such as flexoelectric effect,nonlocal and length scale parameters,elastic foundation stiffness coefficient,porosity coefficient,and boundary conditions on the static bending response of the nanoshell is detected and comprehensively studied.The findings of this study have practical implications for the efficient design and control of comparable systems,such as micro-electromechanical and nano-electromechanical devices.
基金supported in part by the National Natural Science Foundation of China(62125306)Zhejiang Key Research and Development Project(2024C01163)the State Key Laboratory of Industrial Control Technology,China(ICT2024A06)
文摘In recent decades,control performance monitoring(CPM)has experienced remarkable progress in research and industrial applications.While CPM research has been investigated using various benchmarks,the historical data benchmark(HIS)has garnered the most attention due to its practicality and effectiveness.However,existing CPM reviews usually focus on the theoretical benchmark,and there is a lack of an in-depth review that thoroughly explores HIS-based methods.In this article,a comprehensive overview of HIS-based CPM is provided.First,we provide a novel static-dynamic perspective on data-level manifestations of control performance underlying typical controller capacities including regulation and servo:static and dynamic properties.The static property portrays time-independent variability in system output,and the dynamic property describes temporal behavior driven by closed-loop feedback.Accordingly,existing HIS-based CPM approaches and their intrinsic motivations are classified and analyzed from these two perspectives.Specifically,two mainstream solutions for CPM methods are summarized,including static analysis and dynamic analysis,which match data-driven techniques with actual controlling behavior.Furthermore,this paper also points out various opportunities and challenges faced in CPM for modern industry and provides promising directions in the context of artificial intelligence for inspiring future research.
文摘Herein,a one-pot chemical reduction method was reported to prepare folic acid(FA)-stabilized silver nanoclusters(FA@Ag NCs),in which FA,hydrazine hydrate,and silver nitrate were used as capping agent,reducing agent,and precursor,respectively.Several technologies were employed to investigate the structures and optical properties of FA@Ag NCs,including transmission electron microscopy(TEM),X-ray photoelectron spectrometer(XPS),Fourier transform infrared spectrometer(FTIR),X-ray diffractometer(XRD),fluorescence spectrometer,and ultraviolet visible absorption spectrometer.FA@Ag NCs were suggested to be highly dispersed and spherical with a size of around 2.8 nm.Moreover,the maximum excitation and emission wavelengths of FA@Ag NCs were 370 and 447 nm,respectively.Under the optimal detection conditions,FA@Ag NCs could be used to effectively detect malachite green with the linear detection range of 0.5-200μmol·L^(-1).The detection limit was 0.084μmol·L^(-1).The fluorescence-quenching mechanism was ascribed to the static quenching.The detection system based on FA@AgNCs was successfully used for the detection of malachite green in actual samples with good accuracy and reproducibility.
基金supported by Scientific Research Projects Department of Istanbul Technical University.Project Number:MGA-2018-41546.Grant receiver:E.T.
文摘Due to their superior properties, the interest in nanostructures is increasing today in engineering. This study presents a new two-noded curved finite element for analyzing the in-plane static behaviors of curved nanobeams. Opposite to traditional curved finite elements developed by using approximate interpolation functions, the proposed curved finite element is developed by using exact analytical solutions. Although this approach was first introduced for analyzing the mechanical behaviors of macro-scale curved beams by adopting the local theory of elasticity, the exact analytical expressions used in this study were obtained from the solutions of governing equations that were expressed via the differential form of the nonlocal theory of elasticity. Therefore, the effects of shear strain and axial extension included in the analytical formulation are also inherited by the curved finite element developed here. The rigidity matrix and the consistent force vector are developed for a circular finite element. To demonstrate the applicability of the method, static analyses of various curved nanobeams subjected to different boundary conditions and loading scenarios are performed, and the obtained results are compared with the exact analytical ones. The presented study provides an accurate and low computational cost method for researchers to investigate the in-plane static behavior of curved nanobeams.
基金supported by National Key Research and Development Program of China (Grant No.2023YFD1701700)approved by the Experimental Animal Ethics Committee of South China Agricultural University (Approval Number:2025f014)
文摘Background The rapid development of intensive layer breeding has intensified odor pollution that must be paid attention to for the green transformation of the industry. This study used Jingfen No.6 laying hens as the model to systematically evaluate the regulatory effect of compound microalgal powder(Chlorella vulgaris:Spirulina platensis:Haematococcus pluvialis = 3:1:1, 1:3:1, 1:1:3) on ammonia(NH3) emissions from laying hen manure.Results Through analysis of the static NH3production in manure, it was found that the NH3emissions within 24 h in the experimental group with 0.50% compound microalgal powder added were reduced to 6.27–16.84 mg(vs. control: 28.29 mg), achieving a 40.47%–77.84% reduction. GC/MS and 16S rRNA sequencing analyses indicated that the compound microalgal powder intervened in the remodeling of the microbial community and nitrogen metabolism network in manure, driving the transformation from inorganic nitrogen to organic nitrogen, mitigated the proliferation of NH3-producing bacteria(such as Escherichia coli, Klebsiella pneumoniae, Kurthia, and Proteus), and increased the abundance of acid-producing bacteria(such as Leuconostocaceae and Lactobacillaceae). The Spirulina platensis powder group had the best emission reduction effect(reduced by 77.84%), and its mechanism was closely related to the mitigation of Gram-negative bacteria activity by phycocyanin and increased synthesis of aromatic compounds, such as 2,3,5-trimethyl-6-ethylpyrazine.Conclusions This study revealed the mechanism by which the compound microalgal powder reduces NH3emissions by regulating the proliferation of acid-producing bacteria, reshaping the nitrogen metabolism network, and mitigating the activity of NH3-producing bacteria, while providing theoretical and data support for the development of environmentally friendly feed.
基金supported by the Opening Foundation of China National Logging Corporation(CNLC20229C06)the China Petroleum Technical Service Corporation's science project'Development and application of 475 rotary steering system'(2024T-001001)。
文摘Rotary steering systems(RSSs)have been increasingly used to develop horizontal wells.A static push-the-bit RSS uses three hydraulic modules with varying degrees of expansion and contraction to achieve changes in the pushing force acting on the wellbore in different sizes and directions within a circular range,ultimately allowing the wellbore trajectory to be drilled in a predetermined direction.By analyzing its mathematical principles and the actual characteristics of the instrument,a vector force closed-loop control method,including steering and holding modes,was designed.The adjustment criteria for the three hydraulic modules are determined to achieve rapid adjustment of the vector force.The theoretical feasibility of the developed method was verified by comparing its results with the on-site application data of an imported rotary guidance system.
基金supported by the National Natural Science Foundation of China(Grant Nos.51978672 and 52308335)the Natural Science Funding of Hunan Province(Grant No.2023JJ41054)the Natural Science Research Project of Anhui Educational Committee(Grant No.2023AH051170)。
文摘Understanding the reinforcement effect of the newly developed prestressed reinforcement components(PRCs)(a system composed of prestressed steel bars(PSBs),protective sleeves,lateral pressure plates(LPPs),and anchoring elements)is technically significant for the rational design of prestressed subgrade.A three-dimensional finite element model was established and verified based on a novel static model test and utilized to systematically analyze the influence of prestress levels and reinforcement modes on the reinforcement effect of the subgrade.The results show that the PRCs provide additional confining pressure to the subgrade through the diffusion effect of the prestress,which can therefore effectively improve the service performance of the subgrade.Compared to the unreinforced conventional subgrades,the settlements of prestressreinforced subgrades are reduced.The settlement attenuation rate(Rs)near the LPPs is larger than that at the subgrade center,and increasing the prestress positively contributes to the stability of the subgrade structure.In the multi-row reinforcement mode,the reinforcement effect of PRCs can extend from the reinforced area to the unreinforced area.In addition,as the horizontal distance from the LPPs increases,the additional confining pressure converted by the PSBs and LPPs gradually diminishes when spreading to the core load bearing area of the subgrade,resulting in a decrease in the Rs.Under the singlerow reinforcement mode,PRCs can be strategically arranged according to the local areas where subgrade defects readily occurred or observed,to obtain the desired reinforcement effect.Moreover,excessive prestress should not be applied near the subgrade shoulder line to avoid the shear failure of the subgrade shoulder.PRCs can be flexibly used for preventing and treating various subgrade defects of newly constructed or existing railway lines,achieving targeted and classified prevention,and effectively improving the bearing performance and deformation resistance of the subgrade.The research results are instructive for further elucidating the prestress reinforcement effect of PRCs on railway subgrades.
基金supported in part by the National Specialized Research Project(No.XXZ3-XX21-3).
文摘The accuracy of the full-scale aircraft static tests is greatly influenced by the aircraft attitude.This paper proposes an aircraft attitude optimization method based on the characteristics of the test.The aim is to address three typical problems of ttitude control in the full-scale aircraft static tests:(1)The coupling of rigid-body displacement and elastic deformation after large deformation,(2)the difficulty of characterizing the aircraft attitude by measurable structure,and(3)the insufficient adaptability of the center of gravity reference to complex loading conditions.The methodology involves the establishment of two observation coordinate systems,a ground coordinate system and an airframe coordinate system,and two deformation states,before and after airframe deformation.A subsequent analysis of the parameter changes of these two states under different coordinate systems is then undertaken,with the objective being to identify the key parameters affecting the attitude control accuracy of large deformation aircraft.Three optimization objective functions are established according to the test loading characteristics and the purpose of the test:(1)To minimize the full-scale aircraft loading angle error,(2)to minimize the full-scale aircraft loading additional load,and(3)to minimize the full-scale aircraft loading wing root additional bending moment.The optimization calculation results are obtained by using the particle swarm optimization algorithm,and the typical full-scale aircraft static test load condition of large passenger aircraft is taken as an example.The analysis of the results demonstrates that by customizing the measurable structure of the aircraft as the observation point for the aircraft attitude,and by obtaining the translational and rotational control parameters of the observation point during the test based on the optimization objective function,the results are reasonable,and the project can be implemented and used to control the aircraft's attitude more accurately in complex force test conditions.
