According to the basic idea of dual-complementarity, in a simple and unified way proposed by the author, various energy principles in theory of elastic materials with voids can be established systematically, In this p...According to the basic idea of dual-complementarity, in a simple and unified way proposed by the author, various energy principles in theory of elastic materials with voids can be established systematically, In this paper, an important integral relation is given, which can be considered essentially as the generalized pr- inciple of virtual work. Based on this relation, it is possible not only to obtain the principle of virtual work and the reciprocal theorem of work in theory of elastic materials with voids, but also to derive systematically the complementary functionals for the eight-field, six-field, four-field and two-field generalized variational principles, and the principle of minimum potential and complementary energies. Furthermore, with this appro ach, the intrinsic relationship among various principles can be explained clearly.展开更多
According to the basic idea of dual-complementarity,in a simple and unified way proposed by the author,some basic principles in dynamic theory of elastic materials with voids can be established sys- tematically.In thi...According to the basic idea of dual-complementarity,in a simple and unified way proposed by the author,some basic principles in dynamic theory of elastic materials with voids can be established sys- tematically.In this paper, an important integral relation in terms of convolutions is given,which can be con- sidered as the generalized principle of virtual work in mechanics.Based on this relation,it is possible not on- ly to obtain the principle of virtual work and the reciprocal theorem in dynamic theory of elastic materials with voids,but also to derive systematically the complementary functionals for the eight-field,six-field, four-field and two-field simplified Gurtin-type variational principles.Furthermore,with this approach,the in- trinsic relationship among various principles can be explained clearly.展开更多
The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/stra...The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.展开更多
In this paper, the theory of materi als with elastic range by Lucchesi and Podio_Guidugli(1988) has been generalized . It has also shown that there are some difficulties on the definition of back s tress as the “cen...In this paper, the theory of materi als with elastic range by Lucchesi and Podio_Guidugli(1988) has been generalized . It has also shown that there are some difficulties on the definition of back s tress as the “center” of the yield surface in the Cauchy space. The back stres s tensor is Lagrangian,and must be defined in the Lagrangian stress space.展开更多
The Limu tin deposits located in the Nanling tin and tungsten-polymetallic ore belt are now facing resource depletion after decades of exploitation.Peripheral mineral exploration therefore has become an urgent task.Us...The Limu tin deposits located in the Nanling tin and tungsten-polymetallic ore belt are now facing resource depletion after decades of exploitation.Peripheral mineral exploration therefore has become an urgent task.Using mineral exploration around the Limu crisis mines as an example,we introduce a breakthrough method of how the three-field theory,i.e.,the material,energy and spatial fields,is applied to intensively studies areas,a history of years of mineral exploitation and complex ore-forming systems.Taking a cue from Limu regional metallogeny,we based our investigation on the metallogenic information from geology,geophysics,geochemistry and remote sensing.We conducted our study of the three-field integrated information system,associated with metallogenic prognoses from deposits,with assignments and calculations which correct and allocate synthetic metallogenic prognosis by relying on GIS.We submitted a synthetic metallogenic prognosis map of tin in Limu where we delineated three ore target areas.A breakthrough was achieved by finding about 4785 t of tin metal outside the Shiziling deposit,which has been confirmed by drilling.The successful application in Limu shows that this three-field theory is of scientific and practical importance and deserves to be extended to utilization.展开更多
Oilfield M currently has a comprehensive water cut of 73.2%after more than 20 years of development,the reservoir is experiencing both edge-bottom water flooding and injection water flooding,with diverse types of injec...Oilfield M currently has a comprehensive water cut of 73.2%after more than 20 years of development,the reservoir is experiencing both edge-bottom water flooding and injection water flooding,with diverse types of injected water and complex flooding patterns,necessitating the research on logging evaluation methods for water-flooded layers.By introducing the variable multiple injection water material balance theory and combining it with the rock-electric relationship,an analysis of the water flooding mechanism in the study area was conducted.This led to the establishment of the variation characteristics between formation resistivity,water production rate,and saturation under different reservoir types and different salinities of injected water in the area;using the semi-permeable membrane capillary pressure experiment,the relationship between the original formation resistivity and the oil column height was established,deriving the relationship between the water production rate and the formation resistivity drop rate,combining the analysis of the water flooding mechanism mentioned above,allowing for a quantitative assessment of the level of water flooding;optimizing the mixed formation water resistivity calculation model to accurately determine parameters such as remaining oil saturation and water production rate,a set of identification and quantitative evaluation methods for waterflooded layers in Oilfield M was formed.The interpretation accuracy reached 87.5%,providing strong technical support for selecting perforation layers in the oilfield and avoiding highly flooded layers.This is of significant application value for the remaining oil evaluation and efficient development of water-flooded layers in overseas clastic rock oilfields.展开更多
The mechanical response of the human arterial wall under the combined loading of inflation, axial extension, and torsion is examined within the framework of the large deformation hyper-elastic theory. The probability ...The mechanical response of the human arterial wall under the combined loading of inflation, axial extension, and torsion is examined within the framework of the large deformation hyper-elastic theory. The probability of the aneurysm formation is explained with the instability theory of structure, and the probability of its rupture is explained with the strength theory of material. Taking account of the residual stress and the smooth muscle activities, a two layer thick-walled circular cylindrical tube model with fiber-reinforced composite-based incompressible anisotropic hyper-elastic materials is employed to model the mechanical behavior of the arterial wall. The deformation curves and the stress distributions of the arterial wall are given under normal and abnormal conditions. The results of the deformation and the structure instability analysis show that the model can describe the uniform inflation deformation of the arterial wall under normal conditions, as well as formation and growth of an aneurysm under abnormal conditions such as the decreased stiffness of the elastic and collagen fibers. From the analysis of the stresses and the material strength, the rupture of an aneurysm may also be described by this model if the wall stress is larger than its strength.展开更多
Since the seminal work by Kojima et al. in 2009, solar cells based on hybrid organic-inorganic perovskites have attracted considerable attention and experienced an exponential growth, with photovoltaic efficiencies as...Since the seminal work by Kojima et al. in 2009, solar cells based on hybrid organic-inorganic perovskites have attracted considerable attention and experienced an exponential growth, with photovoltaic efficiencies as of today reaching above 22%. Despite such an impressive development, some key scientific issues of these materials, including the presence of toxic lead, the poor long-term device stability under heat and humidity conditions, and the anomalous hysteresis of the current-voltage curves shown by various solar cell devices, still remain unsolved and constitute an important focus of experimental and theoretical researchers throughout the world. Density functional theory calculations have been successfully applied to exploring structural and electronic properties of semiconductors, complementing the experimental results in search and discovery of novel functional materials. In this review, we summarize the current progress in perovskite photovoltaic materials from a theoretical perspective. We discuss design of lead-free perovskite materials, humidity-induced degradation mechanisms and possible origins for the observed solar cell hysteresis, and assess future research directions for advanced perovskite solar cells based on computational materials design and theoretical understanding of intrinsic properties.展开更多
Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosi...Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.展开更多
In this study, free and forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by carbon nanotubes （CNTs） under magnetic field based on modify couple stress theory （MCST） with temper...In this study, free and forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by carbon nanotubes （CNTs） under magnetic field based on modify couple stress theory （MCST） with temperature-variable material propertiesis presented. Also, the boundary conditions at two ends of nano-composite rotating pressurized microbeam reinforced by CNTs are considered as simply supported. The governing equations are obtained based on the Hamilton＇s principle and then computed these equations by using Navier＇s solution. The magnetic field is inserted in the thickness direction of the nano-composite microbeam. The effects of various parameters such as angular velocity, temperature changes, and pressure between of the inside and outside, the magnetic field, material length scale parameter, and volume fraction of nanocomposite microbeam on the natural frequency and response systemare studied. The results show that with increasing volume fraction of nano-composite microbeam, thickness, material length scale parameter, and magnetic fields, the natural frequency increases. The results of this research can be used for optimization of micro-structures and manufacturing sensors, displacement fluid, and drug delivery.展开更多
Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalcogenides(TMDs) materials and improving device performance to desired properties. However, the meth...Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalcogenides(TMDs) materials and improving device performance to desired properties. However, the methods in defect controlcurrently face challenges with overly large operational areas and a lack of precision in targeting specific defects. Therefore,we propose a new method for the precise and universal defect healing of TMD materials, integrating real-time imaging withscanning transmission electron microscopy (STEM). This method employs electron beam irradiation to stimulate the diffusionmigration of surface-adsorbed adatoms on TMD materials grown by low-temperature molecular beam epitaxy (MBE),and heal defects within the diffusion range. This approach covers defect repairs ranging from zero-dimensional vacancydefects to two-dimensional grain orientation alignment, demonstrating its universality in terms of the types of samples anddefects. These findings offer insights into the use of atomic-level focused electron beams at appropriate voltages in STEMfor defect healing, providing valuable experience for achieving atomic-level precise fabrication of TMD materials.展开更多
Spectroscopic and fluorescence properties of Nd 3＋ ions in sodium fluoroborate（SFB） glasses were prepared and characterized through optical absorption,emission and decay measurements.The energy level analysis was c...Spectroscopic and fluorescence properties of Nd 3＋ ions in sodium fluoroborate（SFB） glasses were prepared and characterized through optical absorption,emission and decay measurements.The energy level analysis was carried out using free-ion Hamiltonian model.Experimental oscillator strengths were determined by measuring the area encompassed by the absorption peaks recorded for 1.0 mol.% Nd 3＋-doped glasses.The Judd-Ofelt parameters（2,4,6） were used to evaluate the laser characteristic parameters such as radiative transition probability（A R）,radiative decay time（τ R）,fluorescence branching ratio（β R） and stimulated emission cross-section（σ e） for the 4 F 3/2 metastable state.The fluorescence spectra for different concentrations of Nd 3＋ ions were recorded by exciting the samples at 514.5 nm Ar ＋ ion laser.展开更多
Material Engagement Theory (MET) theorizes artefacts as the emergent outcomes of non-linear processes of formation in which both human and non-human forms of agency are involved. It has proved a useful framework for e...Material Engagement Theory (MET) theorizes artefacts as the emergent outcomes of non-linear processes of formation in which both human and non-human forms of agency are involved. It has proved a useful framework for exploring the architectural design process – which typically involves the mobilisation of multiple tools and materialities – but has not yet been applied to urban design. This paper argues that MET can be applied to the analysis of urban form, helping explain the distributed processes of urban formation. In sketching out an outline theory of urban material engagement, the paper facilitates a dialogue between MET and two theories of urban morphogenesis – SIRN and Space Syntax theory – which explain formal emergence in the urban surface and the urban grid, respectively. Exploring these theories’ analyses of urban formation – and the relationship between urban form and urban social behaviour – the paper outlines a theoretical synthesis which centres on the artefactual nature of urban form.展开更多
The growing interest in the material flow(MF)theory has invoked much interesting research in recent years.Although the MF theory is relatively new,a review of the related literature from a historical perspective shows...The growing interest in the material flow(MF)theory has invoked much interesting research in recent years.Although the MF theory is relatively new,a review of the related literature from a historical perspective shows that MF theory represents a new stage of the evolutionary development of interrelated subjects such as Physical Distribution(PD),Logistics,and Supply Chain Management(SCM).The purpose of this paper is to provide a summative review of the evolution of the subjects of PD,Logistics,and SCM,and their new development,MF theory.The paper aims at tracing how concepts and findings in PD,Logistics,SCM,and MF have been developed and have evolved.The study shows that PD evolved to Logistics in middle of the 1980s;starting from the late 1990s,Logistics has evolved to SCM;and today PD,Logistics,and SCM can be considered to be under the umbrella provided by a new theory called MF theory.This paper points out that MF theory is a necessity to deal with the overwhelming complexity of material flow systems in the global economy of the twenty-first century.展开更多
Based on thermoacoustic theory, a coupled thermal-mechanical model for graphene films is established, and the analytical solutions for thermal-acoustic radiation from a graphene thin film are obtained. The sound press...Based on thermoacoustic theory, a coupled thermal-mechanical model for graphene films is established, and the analytical solutions for thermal-acoustic radiation from a graphene thin film are obtained. The sound pressure of the graphene film generator on different substrates is measured, and the measurement data is compared with the theoretical results. The frequency response from the experimental results is consistent with the theoretical ones, while the measured values are slightly lower than the theoretical ones. Therefore, the accuracy of the proposed theoretical model is verified. It is shown that thermal-acoustic radiation from a graphene thin film reveals a wide frequency response. The sound pressure level increases with the frequency in the low frequency range, while the sound pressure varies smoothly with frequency in the high frequency range. Thus it can be used as excellent thermal generator. When the thermal effusivity of the substrate is smaller, then the sound pressure of grapheme films will be higher. Furthermore, the sound pressure decreases with the increase of heat capacity per unit area of grapheme films. Results will contribute to the mechanism of graphene films generator and its applications in the design of loudspeaker and other related areas.展开更多
This paper demonstrates a new interpretation of the material purchasing management system(MPMS) from the perspective of complex adaptive systems(CAS).Within the framework of CAS,the authors design the self-adaptive me...This paper demonstrates a new interpretation of the material purchasing management system(MPMS) from the perspective of complex adaptive systems(CAS).Within the framework of CAS,the authors design the self-adaptive mechanism of the MPMS responding to the changing environment,such as the change of the price,by using risk measurement theory,modern portfolio theory(MPT) and the information of the material's modifying priority.As a bottom-up systems view,CAS focuses on the individual level and studies system's overall complexity by analyzing the mutual competition and adaptation among the individuals.This paper demonstrates a quantitative description of CAS by discussing the MPMS which can be viewed as a kind of CAS,and makes numerical simulations of Daqing oilfield MPMS.Compared to the benchmarks,the authors set the simulations show that the self-adaptive mechanism adapts well to the change of the material's market price.Hence,this paper accomplishes a numerical simulation of CAS's quantitative self-adaptive mechanism responding to the environment's change.展开更多
基金The project supported by the National Natural Science Foundation of China
文摘According to the basic idea of dual-complementarity, in a simple and unified way proposed by the author, various energy principles in theory of elastic materials with voids can be established systematically, In this paper, an important integral relation is given, which can be considered essentially as the generalized pr- inciple of virtual work. Based on this relation, it is possible not only to obtain the principle of virtual work and the reciprocal theorem of work in theory of elastic materials with voids, but also to derive systematically the complementary functionals for the eight-field, six-field, four-field and two-field generalized variational principles, and the principle of minimum potential and complementary energies. Furthermore, with this appro ach, the intrinsic relationship among various principles can be explained clearly.
基金The project supported by the Foundation of Zhongshan University Advanced Research Center
文摘According to the basic idea of dual-complementarity,in a simple and unified way proposed by the author,some basic principles in dynamic theory of elastic materials with voids can be established sys- tematically.In this paper, an important integral relation in terms of convolutions is given,which can be con- sidered as the generalized principle of virtual work in mechanics.Based on this relation,it is possible not on- ly to obtain the principle of virtual work and the reciprocal theorem in dynamic theory of elastic materials with voids,but also to derive systematically the complementary functionals for the eight-field,six-field, four-field and two-field simplified Gurtin-type variational principles.Furthermore,with this approach,the in- trinsic relationship among various principles can be explained clearly.
基金Project(50575143)supported by the National Natural Science Foundation of ChinaProject(20040248005)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.
文摘In this paper, the theory of materi als with elastic range by Lucchesi and Podio_Guidugli(1988) has been generalized . It has also shown that there are some difficulties on the definition of back s tress as the “center” of the yield surface in the Cauchy space. The back stres s tensor is Lagrangian,and must be defined in the Lagrangian stress space.
文摘The Limu tin deposits located in the Nanling tin and tungsten-polymetallic ore belt are now facing resource depletion after decades of exploitation.Peripheral mineral exploration therefore has become an urgent task.Using mineral exploration around the Limu crisis mines as an example,we introduce a breakthrough method of how the three-field theory,i.e.,the material,energy and spatial fields,is applied to intensively studies areas,a history of years of mineral exploitation and complex ore-forming systems.Taking a cue from Limu regional metallogeny,we based our investigation on the metallogenic information from geology,geophysics,geochemistry and remote sensing.We conducted our study of the three-field integrated information system,associated with metallogenic prognoses from deposits,with assignments and calculations which correct and allocate synthetic metallogenic prognosis by relying on GIS.We submitted a synthetic metallogenic prognosis map of tin in Limu where we delineated three ore target areas.A breakthrough was achieved by finding about 4785 t of tin metal outside the Shiziling deposit,which has been confirmed by drilling.The successful application in Limu shows that this three-field theory is of scientific and practical importance and deserves to be extended to utilization.
基金supported by Research on Reservoir Formation Patterns and Risk Exploration in Key Overseas Basins(25ZYGJCJ011)。
文摘Oilfield M currently has a comprehensive water cut of 73.2%after more than 20 years of development,the reservoir is experiencing both edge-bottom water flooding and injection water flooding,with diverse types of injected water and complex flooding patterns,necessitating the research on logging evaluation methods for water-flooded layers.By introducing the variable multiple injection water material balance theory and combining it with the rock-electric relationship,an analysis of the water flooding mechanism in the study area was conducted.This led to the establishment of the variation characteristics between formation resistivity,water production rate,and saturation under different reservoir types and different salinities of injected water in the area;using the semi-permeable membrane capillary pressure experiment,the relationship between the original formation resistivity and the oil column height was established,deriving the relationship between the water production rate and the formation resistivity drop rate,combining the analysis of the water flooding mechanism mentioned above,allowing for a quantitative assessment of the level of water flooding;optimizing the mixed formation water resistivity calculation model to accurately determine parameters such as remaining oil saturation and water production rate,a set of identification and quantitative evaluation methods for waterflooded layers in Oilfield M was formed.The interpretation accuracy reached 87.5%,providing strong technical support for selecting perforation layers in the oilfield and avoiding highly flooded layers.This is of significant application value for the remaining oil evaluation and efficient development of water-flooded layers in overseas clastic rock oilfields.
基金Project supported by the National Natural Science Foundation of China (Nos.10772104 and 10872045)the Innovation Project of the Shanghai Municipal Education Commission (No.09YZ12)the Shanghai Leading Academic Discipline Project (No.S30106)
文摘The mechanical response of the human arterial wall under the combined loading of inflation, axial extension, and torsion is examined within the framework of the large deformation hyper-elastic theory. The probability of the aneurysm formation is explained with the instability theory of structure, and the probability of its rupture is explained with the strength theory of material. Taking account of the residual stress and the smooth muscle activities, a two layer thick-walled circular cylindrical tube model with fiber-reinforced composite-based incompressible anisotropic hyper-elastic materials is employed to model the mechanical behavior of the arterial wall. The deformation curves and the stress distributions of the arterial wall are given under normal and abnormal conditions. The results of the deformation and the structure instability analysis show that the model can describe the uniform inflation deformation of the arterial wall under normal conditions, as well as formation and growth of an aneurysm under abnormal conditions such as the decreased stiffness of the elastic and collagen fibers. From the analysis of the stresses and the material strength, the rupture of an aneurysm may also be described by this model if the wall stress is larger than its strength.
基金support of the National Natural Science Foundation of China,grant nos.21473183 and 21303079the Foundation for Polish Science,grant no.42.2016,for support through the START 2016 program+1 种基金US National Science Foundation,grant no.CHE-1565704US Department of Energy,grant no.DE-SC0014429,for financial support
文摘Since the seminal work by Kojima et al. in 2009, solar cells based on hybrid organic-inorganic perovskites have attracted considerable attention and experienced an exponential growth, with photovoltaic efficiencies as of today reaching above 22%. Despite such an impressive development, some key scientific issues of these materials, including the presence of toxic lead, the poor long-term device stability under heat and humidity conditions, and the anomalous hysteresis of the current-voltage curves shown by various solar cell devices, still remain unsolved and constitute an important focus of experimental and theoretical researchers throughout the world. Density functional theory calculations have been successfully applied to exploring structural and electronic properties of semiconductors, complementing the experimental results in search and discovery of novel functional materials. In this review, we summarize the current progress in perovskite photovoltaic materials from a theoretical perspective. We discuss design of lead-free perovskite materials, humidity-induced degradation mechanisms and possible origins for the observed solar cell hysteresis, and assess future research directions for advanced perovskite solar cells based on computational materials design and theoretical understanding of intrinsic properties.
基金Supported by the National Sci-Tech Support Plan(2015BAD21B05)China Scholarship Council(201408320127)
文摘Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.
基金the Iranian Nanotechnology Development Committee for their financial supportthe University of Kashan (463855/7)
文摘In this study, free and forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by carbon nanotubes （CNTs） under magnetic field based on modify couple stress theory （MCST） with temperature-variable material propertiesis presented. Also, the boundary conditions at two ends of nano-composite rotating pressurized microbeam reinforced by CNTs are considered as simply supported. The governing equations are obtained based on the Hamilton＇s principle and then computed these equations by using Navier＇s solution. The magnetic field is inserted in the thickness direction of the nano-composite microbeam. The effects of various parameters such as angular velocity, temperature changes, and pressure between of the inside and outside, the magnetic field, material length scale parameter, and volume fraction of nanocomposite microbeam on the natural frequency and response systemare studied. The results show that with increasing volume fraction of nano-composite microbeam, thickness, material length scale parameter, and magnetic fields, the natural frequency increases. The results of this research can be used for optimization of micro-structures and manufacturing sensors, displacement fluid, and drug delivery.
基金the Beijing Natural Science Foundation(Grant Nos.JQ24010 and Z220020)the Fundamental Research Funds for the Central Universities,and the National Natural Science Foundation of China(Grant No.52273279)Project supported by the Electron Microscopy Laboratory of Peking University,China for the use of Nion U-HERMES200 scanning transmission electron microscopy.We thank Materials Processing and Analysis Center,Peking University,for assistance with TEM characterization.The electron microscopy work was through a user project at Center of Oak Ridge National Laboratory(ORNL)for Nanophase Materials Sciences(CNMS),which is a DOE Office of Science User Facility.
文摘Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalcogenides(TMDs) materials and improving device performance to desired properties. However, the methods in defect controlcurrently face challenges with overly large operational areas and a lack of precision in targeting specific defects. Therefore,we propose a new method for the precise and universal defect healing of TMD materials, integrating real-time imaging withscanning transmission electron microscopy (STEM). This method employs electron beam irradiation to stimulate the diffusionmigration of surface-adsorbed adatoms on TMD materials grown by low-temperature molecular beam epitaxy (MBE),and heal defects within the diffusion range. This approach covers defect repairs ranging from zero-dimensional vacancydefects to two-dimensional grain orientation alignment, demonstrating its universality in terms of the types of samples anddefects. These findings offer insights into the use of atomic-level focused electron beams at appropriate voltages in STEMfor defect healing, providing valuable experience for achieving atomic-level precise fabrication of TMD materials.
文摘Spectroscopic and fluorescence properties of Nd 3＋ ions in sodium fluoroborate（SFB） glasses were prepared and characterized through optical absorption,emission and decay measurements.The energy level analysis was carried out using free-ion Hamiltonian model.Experimental oscillator strengths were determined by measuring the area encompassed by the absorption peaks recorded for 1.0 mol.% Nd 3＋-doped glasses.The Judd-Ofelt parameters（2,4,6） were used to evaluate the laser characteristic parameters such as radiative transition probability（A R）,radiative decay time（τ R）,fluorescence branching ratio（β R） and stimulated emission cross-section（σ e） for the 4 F 3/2 metastable state.The fluorescence spectra for different concentrations of Nd 3＋ ions were recorded by exciting the samples at 514.5 nm Ar ＋ ion laser.
文摘Material Engagement Theory (MET) theorizes artefacts as the emergent outcomes of non-linear processes of formation in which both human and non-human forms of agency are involved. It has proved a useful framework for exploring the architectural design process – which typically involves the mobilisation of multiple tools and materialities – but has not yet been applied to urban design. This paper argues that MET can be applied to the analysis of urban form, helping explain the distributed processes of urban formation. In sketching out an outline theory of urban material engagement, the paper facilitates a dialogue between MET and two theories of urban morphogenesis – SIRN and Space Syntax theory – which explain formal emergence in the urban surface and the urban grid, respectively. Exploring these theories’ analyses of urban formation – and the relationship between urban form and urban social behaviour – the paper outlines a theoretical synthesis which centres on the artefactual nature of urban form.
基金This study was supported by the Major Research Program of the National Natural Science Foundation of China[grant number 71132008]Planning Fund Program for Social Science in China,Ministry of Education of China[grant number 10YJA630059]+1 种基金National Key Technology Research and Development Program of the Ministry of Science and Technology of China[grant number 2013BAH11F00]the Program of the Institute for Industrial Security in China[grant number B13L00050].
文摘The growing interest in the material flow(MF)theory has invoked much interesting research in recent years.Although the MF theory is relatively new,a review of the related literature from a historical perspective shows that MF theory represents a new stage of the evolutionary development of interrelated subjects such as Physical Distribution(PD),Logistics,and Supply Chain Management(SCM).The purpose of this paper is to provide a summative review of the evolution of the subjects of PD,Logistics,and SCM,and their new development,MF theory.The paper aims at tracing how concepts and findings in PD,Logistics,SCM,and MF have been developed and have evolved.The study shows that PD evolved to Logistics in middle of the 1980s;starting from the late 1990s,Logistics has evolved to SCM;and today PD,Logistics,and SCM can be considered to be under the umbrella provided by a new theory called MF theory.This paper points out that MF theory is a necessity to deal with the overwhelming complexity of material flow systems in the global economy of the twenty-first century.
基金supported by the National Natural Science Foundation of China(51375321)Soochow University "Soochow Scholars" program(R513300116)
文摘Based on thermoacoustic theory, a coupled thermal-mechanical model for graphene films is established, and the analytical solutions for thermal-acoustic radiation from a graphene thin film are obtained. The sound pressure of the graphene film generator on different substrates is measured, and the measurement data is compared with the theoretical results. The frequency response from the experimental results is consistent with the theoretical ones, while the measured values are slightly lower than the theoretical ones. Therefore, the accuracy of the proposed theoretical model is verified. It is shown that thermal-acoustic radiation from a graphene thin film reveals a wide frequency response. The sound pressure level increases with the frequency in the low frequency range, while the sound pressure varies smoothly with frequency in the high frequency range. Thus it can be used as excellent thermal generator. When the thermal effusivity of the substrate is smaller, then the sound pressure of grapheme films will be higher. Furthermore, the sound pressure decreases with the increase of heat capacity per unit area of grapheme films. Results will contribute to the mechanism of graphene films generator and its applications in the design of loudspeaker and other related areas.
基金supported by Key laboratory of Management,Decision and Information Systems,Chinese Academy of Science
文摘This paper demonstrates a new interpretation of the material purchasing management system(MPMS) from the perspective of complex adaptive systems(CAS).Within the framework of CAS,the authors design the self-adaptive mechanism of the MPMS responding to the changing environment,such as the change of the price,by using risk measurement theory,modern portfolio theory(MPT) and the information of the material's modifying priority.As a bottom-up systems view,CAS focuses on the individual level and studies system's overall complexity by analyzing the mutual competition and adaptation among the individuals.This paper demonstrates a quantitative description of CAS by discussing the MPMS which can be viewed as a kind of CAS,and makes numerical simulations of Daqing oilfield MPMS.Compared to the benchmarks,the authors set the simulations show that the self-adaptive mechanism adapts well to the change of the material's market price.Hence,this paper accomplishes a numerical simulation of CAS's quantitative self-adaptive mechanism responding to the environment's change.
