Auxetic materials have been extensively studied for their design,fabrication and mechanical properties.These material systems exhibit unique mechanical characteristics such as high impact resistance,shear strength,and...Auxetic materials have been extensively studied for their design,fabrication and mechanical properties.These material systems exhibit unique mechanical characteristics such as high impact resistance,shear strength,and energy absorption capacity.Most existing auxetic materials are two-dimensional(2D)and demonstrate half-auxetic behavior,characterized by a negative Poisson's ratio when subjected to either tensile or compressive forces.Here,we present novel three-dimensional(3D)auxetic mechanical metamaterials,termed coupling chiral cuboids,capable of achieving negative Poisson's ratio under both tension and compression.We perform experiments,theoretical analysis,and numerical simulations to validate the wholly auxetic response of the proposed coupling chiral cuboids.Parametric studies are carried out to investigate the effects of structural parameters on the elastic modulus and Poisson's ratio of the coupling chiral cuboids.The results imply that the Poisson's ratio sign-switching from negative to positive can be implemented by manipulating the thickness of Z-shaped ligaments.Finally,the potential application of the coupling chiral cuboids as inner cores for impact-resistant sandwich panels is envisioned and validated.Test results demonstrate a remarkable 49.3%enhancement in energy absorption compared to conventional solidmaterials.展开更多
To enhance the efficiency of wind energy harvesters,aerodynamic modifications to bluff bodies prove highly effective.This study introduces two innovative galloping piezoelectric energy harvesters(GPEHs)equipped with t...To enhance the efficiency of wind energy harvesters,aerodynamic modifications to bluff bodies prove highly effective.This study introduces two innovative galloping piezoelectric energy harvesters(GPEHs)equipped with two symmetrical splitters on a cuboid bluff body:GPEH with upstream splitters(GPEH-US)and GPEH with downstream splitters(GPEH-DS).Wind tunnel experiments evaluated the impact of splitter angle and length on energy harvesting performance across varying wind speeds.The results indicate that larger splitter angles and shorter lengths are more favorable for energy harvesting in GPEH-US.The optimal configuration,determined as GPEH-US with α=90°,L=0.4D,reduces the threshold wind speed,expands the effective wind speed range for energy harvesting,and increases maximum voltage and power output by over 99%,301%,respectively,compared with conventional GPEH.Conversely,GPEH-DS are less effective for energy harvesting but demonstrate potential in vibration control applications.Computational fluid dynamics(CFD)simulations using the OpenFOAM toolbox qualitatively elucidate the physical mechanisms driving these results.A larger splitter angle enables secondary small-scale vortices(SV)to absorb more energy,accelerates boundary layer separation,intensifies and disorderly vortex shedding,enhances aerodynamic instability,and improves energy harvesting performance.展开更多
As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X =Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. T...As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X =Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. The perovskite materials with ID and 2D shapes were widely prepared and studied for Fabry-Perot mode and whispering-gallery-mode (WGM) microcavities, but cuboid-shape is rarely reported. In this work, we successfully fabricated single crystal cuboid-shaped MAPbBr3 perovskite w让h different morphologies, named microcuboid-MAPbBr3 (M-MAPbBr3) and multi-step-MAPbBr3 (MSMAPbBr3), via solvothermal method. Furthermore, the as-prepared *crystals excitonic recombination lifetime under different pumping energy density was studied by time-resolved photoiuminescence (TRPL). Based on controllable morphology and remarkable lasing properties, these cuboid shaped single crystal perovskite could be a promising candidate for small laser, and other optoelectronic devices.展开更多
The drag on non-spherical particles is an important basic parameter for multi-phase flows such as in biomass combustion, chemical blending, and mineral processing. Though there is much experimental research on such pa...The drag on non-spherical particles is an important basic parameter for multi-phase flows such as in biomass combustion, chemical blending, and mineral processing. Though there is much experimental research on such particles, there are few results for cuboids. This paper presents data for cuboids with a square base in static glycerin-water solutions of various volume concentrations. Complex motions were observed and characterized. A dimensionless expression is given for terminal velocity ut as a function of Archimedes number Ar which is used to develop an accurate correlation for friction factor CD. The accuracy of the correlation is 7.9% compared to experimental data in the literature. For both square plates and square rods, the terminal velocity per unit mass, ut/mp, was used to characterize the influence of narticle geometry on velocity, which was shown to be linear.展开更多
Vertical orthogonal joints are a common feature in shallow crustal rocks.There are several competing theories for their formation despite the ubiquity.We examined the exceptional exposures of orthogonal joints in flat...Vertical orthogonal joints are a common feature in shallow crustal rocks.There are several competing theories for their formation despite the ubiquity.We examined the exceptional exposures of orthogonal joints in flat-lying Ordovician limestone beds from the Havre-Saint-Pierre Region in Quebec,Canada(north shore of Saint-Lawrence River)to test conceptual models of joint formation in a natural setting.In the region,the spacing of cross-joints is consistently larger than the spacing of systematic joints by a factor of 1.5 approximately.The joint-spacing-to-bed-thickness ratios(s/t)are much larger in these beds(s/t=4.3 for systematic joints,and 6.4 for cross-joints)than those in higher strained strata along the south shore of the Saint-Lawrence River(s/t=1),highlighting the effect of tectonic strain in decreasing fracture spacing and block size.The high values of s/t indicate that cross-joint formation was unlikely caused by a switch from compression to tension once a critical s/t ratio for systematic joints was reached(as hypothesized in previous studies).We proposed a new model for the formation of orthogonal joint systems where the principal stress axes locally switch during the formation of systematic fractures.The presence of ladder-shaped orthogonal joints suggests a state of effective stress withσ_(1)^(∗)≫0>σ_(2)^(∗)>σ_(3)^(∗)and whereσ_(2)^(∗)-σ_(3)^(∗)is within the range of fracture strength variability at the time of fracture.This research provides a new mechanical model for the formation of orthogonal joint systems and cuboidal blocks.展开更多
Most of the current computing methods used to determine the magnetic field of a uniformly magnetized cuboid assume that the observation point is located in the upper half space without a source. However, such methods ...Most of the current computing methods used to determine the magnetic field of a uniformly magnetized cuboid assume that the observation point is located in the upper half space without a source. However, such methods may generate analytical singularities for conditions of undulating terrain. Based on basic geomagnetic field theories, in this study an improved magnetic field expression is derived using an integration method of variable substitution, and all singularity problems for the entire space without a source are discussed and solved. This integration process is simpler than that of previous methods, and final integral results with a more uniform form. AT at all points in the source-flee space can be calculated without requiring coordinate transformation; thus forward modeling is also simplified. Corresponding model tests indicate that the new magnetic field expression is more correct because there is no analytical singularity and can be used with undulating terrain.展开更多
Three-dimensional medical image visualization becomes an essential part for medical field, including computer aided diagnosis, surgery planning and simulation, artificial limb surgery, radiotherapy planning, and teach...Three-dimensional medical image visualization becomes an essential part for medical field, including computer aided diagnosis, surgery planning and simulation, artificial limb surgery, radiotherapy planning, and teaching etc. In this paper, marching cubes algorithm is adopted to reconstruct the 3-D images for the CT image sequence in DICOM format under theVC++6.0 and the visual package VTK platform. The relatively simple interactive operations such as rotation and transfer can be realized on the platform. Moreover, the normal vector and interior point are calculated to form the virtual clipping plane, which is then used to incise the 3-D object. Information of the virtual slice can be obtained, in the mean while the virtual slice images are displayed on the screen. The technique can realize the real time interaction extraction of virtual slice on 3-D CT image. The cuboids structured can be zoomed, moved and eircumrotated by operating mouse to incise the 3-D reconstruction object. Real time interaction can be realized by clipping the reconstruction object. The coordinates can be acquired by the mouse clicking in the 3D space, to realize the point mouse pick-up as well angle and distance interactive measurement. We can get quantitative information about 3-D images through measurement.展开更多
A simplified method is proposed for analyzing the overpressure history of an optional point on the walls of a closed cuboid due to its internal optional point-explosion. Firstly, the overpressure histories of all node...A simplified method is proposed for analyzing the overpressure history of an optional point on the walls of a closed cuboid due to its internal optional point-explosion. Firstly, the overpressure histories of all nodes on the walls of a cube with a side-length of 2 m are computed under a reference-charge explosion at each node of its inner space using the LS-DYNA software, and then are collected to form a reference database. Next, with the thought of the isoparametric finite element, an interpolating algori...展开更多
Cuboid fractures due to the particular bone anatomy and its protected location in the midfoot are rare, and they are usually associated with complex injuries of the foot. Clinical examination to diagnose these fractur...Cuboid fractures due to the particular bone anatomy and its protected location in the midfoot are rare, and they are usually associated with complex injuries of the foot. Clinical examination to diagnose these fractures should be detailed and the differential diagnosis, especially in the case of vague symptoms, should include the exclusion of all lateral foot pain causes. Conventional radiographs do not always reveal occult fractures, which can be under diagnosed especially in children. In this case, further investigation including magnetic resonance imaging or scintigraphy may be required. The treatment of these injuries depends on the particular fracture characteristics. Non-displaced isolated fractures of the cuboid bone can be effectively treated conservatively by immobilization and by avoiding weight bearing on the injured leg. In the case of shortening of the lateral column> 3 mm or articular displacement > 1 mm, surgical management of the fracture is mandatory in order to avoid negative biomechanical and functional consequences for the foot and adverse effects such as arthritis and stiffness as well as painful gait. In this review, an update on diagnosis and management of cuboid fractures is presented.展开更多
Icosahedral quasicrystals are the most important and thermodynamically stable in all about 200 kinds of quasicrystals currently observed. Beyond the scope of classical elasticity, apart from a phonon displacement fiel...Icosahedral quasicrystals are the most important and thermodynamically stable in all about 200 kinds of quasicrystals currently observed. Beyond the scope of classical elasticity, apart from a phonon displacement field, there is a phason displacement field in the elasticity of the quasicrystal, which induces an important effect on the mechanical properties of the material and makes an analytical solution difficult to obtain. In this paper, a finite element algorithm for the static elasticity of icosahedral quasicrystals is developed by transforming the elastic boundary value problem of the icosahedral quasicrystals into an equivalent variational problem. Analytical and numerical solutions for an icosahedral A1-Pd-Mn quasicrystal cuboid subjected to a uniaxial tension with different phonon-phason coupling parameters are given to verify the validity of the numerical approach. A comparison between the analytical and numerical solutions of the specimen demonstrates the accuracy and efficiency of the present algorithm. Finally, in order to reveal the fracture behavior of the icosahedral A1-Pd-Mn quasicrystal, a cracked specimen with a finite size of matter is investigated, both with and without phonon-phason coupling. Meanwhile, the geometry factors are calculated, including the stress intensity factor and the crack opening displacement for the finite-size specimen. Computational results reveal the importance of pbonon-phason coupling effect on the icosahedral A1-Pd-Mn quasicrystal. Furthermore, the finite element procedure can be used to solve more complicated boundary value problems.展开更多
The dynamics of granular material discharging from a cuboid but thin hopper,including the hopper flow and granular jet,are investigated via discrete element method(DEM)simulations.The slot width is varied to study its...The dynamics of granular material discharging from a cuboid but thin hopper,including the hopper flow and granular jet,are investigated via discrete element method(DEM)simulations.The slot width is varied to study its influence on the flow.It is found the flow in the cuboid hopper has similarity with the flow in two-dimensional(2D)hopper.When the slot width is large,the flowrate is higher than the predicted value from Beverloo’s law and the velocity distribution is not Gaussian-like.For granular jet,there is a transition with varying slot width.For large slot width,there is a dense core in the jet and the variations of velocities and density are relatively small.Finally,the availability of continuum model is assessed and the results show that the performance with large slot width is better than that with small slot width.展开更多
To systematically assess the rockburst proneness considering specimen shape,multiple groups of laboratory tests were performed on 5 rock materials in cylindrical and cuboid shapes.The linear energy storage(LES)law of ...To systematically assess the rockburst proneness considering specimen shape,multiple groups of laboratory tests were performed on 5 rock materials in cylindrical and cuboid shapes.The linear energy storage(LES)law of both cylindrical and cuboid rock specimens under uniaxial compressive load was confirmed,and the energy storage coefficient was found to be unrelated to specimen shape.On the basis of LES law,two rockburst proneness indexes,namely the strain energy storage index(W_(et))and the potential energy of elastic strain(PES),were modified.Subsequently,the W_(et),PES,peak-strength strain energy storage index(W_(et))p,and peak-strength potential energy of elastic strain(PESp)were used to assess the rockburst proneness of the cylindrical and cuboid specimens.In addition,the fragment ejection course of specimens under test was recorded by a high-speed camera.Then,the rockburst proneness judgments obtained from the 4 indexes were compared with the qualitative data during rock destruction.The results show that,under similar stress conditions,specimen shape has an ignorable effect on the rockburst proneness as a whole.The judgment accuracy of the two modified indexes,especially that of the PESp,is favorably improved to evaluate the rockburst proneness of both cylindrical and cuboid specimens.However,misjudgment ofW_(et)^(p)and PESp may still occur in the assessment of rockburst proneness as these two indexes only consider the energy state before rock peak strength and the W_(et)^(p)is formulated in a ratio form.展开更多
Traveling Salesman Problem (TSP) is one of the most widely studied real world problems of finding the shortest (minimum cost) possible route that visits each node in a given set of nodes (cities) once and then returns...Traveling Salesman Problem (TSP) is one of the most widely studied real world problems of finding the shortest (minimum cost) possible route that visits each node in a given set of nodes (cities) once and then returns to origin city. The optimization of cuboid areas has potential samples that can be adapted to real world. Cuboid surfaces of buildings, rooms, furniture etc. can be given as examples. Many optimization algorithms have been used in solution of optimization problems at present. Among them, meta-heuristic algorithms come first. In this study, ant colony optimization, one of meta-heuristic methods, is applied to solve Euclidian TSP consisting of nine different sized sets of nodes randomly placed on a cuboid surface. The performance of this method is shown in tests.展开更多
This paper investigates the flux-pinning-induced stress behaviors in a long superconducting slab with a central cuboid hole.The distribution of flux density is analytically derived for the critical current density of ...This paper investigates the flux-pinning-induced stress behaviors in a long superconducting slab with a central cuboid hole.The distribution of flux density is analytically derived for the critical current density of Kim model by considering the effects of the hole.The concentration of stress for both of the zero-field cooling(ZFC)and the field cooling(FC)magnetization processes are investigated through numerical simulation by using finite element method.The results indicate the potential failure mode varies with the height-width ratio and the dimensions of the hole.Different to the case of infinite hole height,the stress concentration behavior for the FC process is more critical when the dimensions of the hole are similar.The findings in this paper are useful for understanding of the degrade mechanism of superconductor in service and the design of new system.展开更多
Two novel Co-based clusters with the 2-(hydroxylmethyl)pyridine(hmpH)ligand,formulated as[Co_(3)(hmp)_(6)(hmpH)]×2NO_(3)×3H_(2)O(ZTU-3)and[Co_(4)(hmp)_(4)(CH3CO_(2))2(H_(2)O)_(4)]×2NO_(3)(ZTU-4),have be...Two novel Co-based clusters with the 2-(hydroxylmethyl)pyridine(hmpH)ligand,formulated as[Co_(3)(hmp)_(6)(hmpH)]×2NO_(3)×3H_(2)O(ZTU-3)and[Co_(4)(hmp)_(4)(CH3CO_(2))2(H_(2)O)_(4)]×2NO_(3)(ZTU-4),have been successfully synthesized and structurally characterized.ZTU-3 features a triangular core geometry,while ZTU-4 exhibits a cuboidal core geometry.In addition,the magnetic properties of ZTU-3 and ZTU-4 are also all investigated.展开更多
The goal of our research was to determine a coupling between information theory, geometry and multi-dimensional projections. This was accomplished after preliminary mathematics was presented to determine an alternativ...The goal of our research was to determine a coupling between information theory, geometry and multi-dimensional projections. This was accomplished after preliminary mathematics was presented to determine an alternative method for the illustration of multi-dimensional spaces. That was developed with a unique series that gives structure to integer exponents of power sets. The desired coupling is concisely illustrated in a single figure which includes three cyclic phases that are isomorphic to the three phases of Euclidian, rectangular cuboids. The series enables projections between n- and m-dimensional volumes. The associated figure also illustrates how vertical and/or horizontal symmetry breaking or symmetry emits or absorbs information.展开更多
This paper introduces a novel concept of information as the logarithm of a countable subset drawn from an uncountable power set,where the countable subset represents“bits”(or mass)and the power set represents the“i...This paper introduces a novel concept of information as the logarithm of a countable subset drawn from an uncountable power set,where the countable subset represents“bits”(or mass)and the power set represents the“image”(or structure).Experimentally,the macroscopic deformation of author-related information-bearing materials is reported,showing a physical manifestation of this relationship between information and structure.Theoretically,a multidirectional projection function with floor functions creates directional cuboid volumes,connecting countable information to spatial structures.The observed conversion of information to mechanical energy associated with this deformation displays energy scales much greater than the thermodynamic limits set by Landauer’s Principle for information erasure.This significant increase indicates a potentially different and more efficient mechanism for utilizing the physical consequences of information,suggesting a potential change in the approach to energy transduction.展开更多
In this paper,we investigate the possibility of using the heterogeneous materials,with cuboid metallic inclusions inside a dielectric substrate(host)to control the effective permittivity.We find that in the gigahertz ...In this paper,we investigate the possibility of using the heterogeneous materials,with cuboid metallic inclusions inside a dielectric substrate(host)to control the effective permittivity.We find that in the gigahertz range,such a material demonstrates a significantly larger permittivity compared to the pure dielectric substrate.Three principal orientations of microscale cuboid inclusions have been taken into account in this study.The highest permittivity is observed when the orientation provides the largest polarization(electric dipole moment).The detrimental side effect of the metallic inclusion,which leads to the decrease of the effective magnetic permeability,can be suppressed by the proper choice of shape and orientation of the inclusions.This choice can in fact reduce the induced current and hence maximize the permeability.The dissipative losses are shown to be negligible in the relevant range of frequencies and cuboid dimensions.展开更多
基金support of the National Key R&D Program of China(2023YFC3008100)the Startup Fund of the One-Hundred Talent Program at the Zhejiang University.A.H.A.acknowledges the support of the National Science Foundation(NSF)CAREER award(CMMI-2235494).
文摘Auxetic materials have been extensively studied for their design,fabrication and mechanical properties.These material systems exhibit unique mechanical characteristics such as high impact resistance,shear strength,and energy absorption capacity.Most existing auxetic materials are two-dimensional(2D)and demonstrate half-auxetic behavior,characterized by a negative Poisson's ratio when subjected to either tensile or compressive forces.Here,we present novel three-dimensional(3D)auxetic mechanical metamaterials,termed coupling chiral cuboids,capable of achieving negative Poisson's ratio under both tension and compression.We perform experiments,theoretical analysis,and numerical simulations to validate the wholly auxetic response of the proposed coupling chiral cuboids.Parametric studies are carried out to investigate the effects of structural parameters on the elastic modulus and Poisson's ratio of the coupling chiral cuboids.The results imply that the Poisson's ratio sign-switching from negative to positive can be implemented by manipulating the thickness of Z-shaped ligaments.Finally,the potential application of the coupling chiral cuboids as inner cores for impact-resistant sandwich panels is envisioned and validated.Test results demonstrate a remarkable 49.3%enhancement in energy absorption compared to conventional solidmaterials.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52271282,51909189 and 52277227)supported by the Open fund of Key Laboratory of Low-grade Energy Utilization Technologies and Systems,Ministry of Education of China,Chongqing University,(Grant No.LLEUTS-202410)+2 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010846)the Shenzhen Science and Technology Programme(Grant Nos.RCYX20231211090210018,WDZC20231125203917001)the Tsinghua Shenzhen International Graduate School via the Scientific Research Start-Up Funds(Grant No.QD2021023C).
文摘To enhance the efficiency of wind energy harvesters,aerodynamic modifications to bluff bodies prove highly effective.This study introduces two innovative galloping piezoelectric energy harvesters(GPEHs)equipped with two symmetrical splitters on a cuboid bluff body:GPEH with upstream splitters(GPEH-US)and GPEH with downstream splitters(GPEH-DS).Wind tunnel experiments evaluated the impact of splitter angle and length on energy harvesting performance across varying wind speeds.The results indicate that larger splitter angles and shorter lengths are more favorable for energy harvesting in GPEH-US.The optimal configuration,determined as GPEH-US with α=90°,L=0.4D,reduces the threshold wind speed,expands the effective wind speed range for energy harvesting,and increases maximum voltage and power output by over 99%,301%,respectively,compared with conventional GPEH.Conversely,GPEH-DS are less effective for energy harvesting but demonstrate potential in vibration control applications.Computational fluid dynamics(CFD)simulations using the OpenFOAM toolbox qualitatively elucidate the physical mechanisms driving these results.A larger splitter angle enables secondary small-scale vortices(SV)to absorb more energy,accelerates boundary layer separation,intensifies and disorderly vortex shedding,enhances aerodynamic instability,and improves energy harvesting performance.
基金supported by the National Natural Science Foundation of China(11674023,51331002,51622205,61675027,61505010,51502018,51525202 and 51432005)111 Project(B170003)+2 种基金the National Key Research and Development Program of China(2016YFA0202703)Beijing Natural Science Foundation(4181004 and 4182080)the ‘‘Thousand Talents” Program of China for Pioneering Researchers and Innovative Teams(U1404619)
文摘As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X =Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. The perovskite materials with ID and 2D shapes were widely prepared and studied for Fabry-Perot mode and whispering-gallery-mode (WGM) microcavities, but cuboid-shape is rarely reported. In this work, we successfully fabricated single crystal cuboid-shaped MAPbBr3 perovskite w让h different morphologies, named microcuboid-MAPbBr3 (M-MAPbBr3) and multi-step-MAPbBr3 (MSMAPbBr3), via solvothermal method. Furthermore, the as-prepared *crystals excitonic recombination lifetime under different pumping energy density was studied by time-resolved photoiuminescence (TRPL). Based on controllable morphology and remarkable lasing properties, these cuboid shaped single crystal perovskite could be a promising candidate for small laser, and other optoelectronic devices.
基金supported by the Major Program of the National Natural Science Foundation of China with Grant No. 10632070
文摘The drag on non-spherical particles is an important basic parameter for multi-phase flows such as in biomass combustion, chemical blending, and mineral processing. Though there is much experimental research on such particles, there are few results for cuboids. This paper presents data for cuboids with a square base in static glycerin-water solutions of various volume concentrations. Complex motions were observed and characterized. A dimensionless expression is given for terminal velocity ut as a function of Archimedes number Ar which is used to develop an accurate correlation for friction factor CD. The accuracy of the correlation is 7.9% compared to experimental data in the literature. For both square plates and square rods, the terminal velocity per unit mass, ut/mp, was used to characterize the influence of narticle geometry on velocity, which was shown to be linear.
基金The authors express their gratitude to the Natural Sciences and Engineering Research Council of Canada for financial support through a Discovery Grant(Grant No.06408).
文摘Vertical orthogonal joints are a common feature in shallow crustal rocks.There are several competing theories for their formation despite the ubiquity.We examined the exceptional exposures of orthogonal joints in flat-lying Ordovician limestone beds from the Havre-Saint-Pierre Region in Quebec,Canada(north shore of Saint-Lawrence River)to test conceptual models of joint formation in a natural setting.In the region,the spacing of cross-joints is consistently larger than the spacing of systematic joints by a factor of 1.5 approximately.The joint-spacing-to-bed-thickness ratios(s/t)are much larger in these beds(s/t=4.3 for systematic joints,and 6.4 for cross-joints)than those in higher strained strata along the south shore of the Saint-Lawrence River(s/t=1),highlighting the effect of tectonic strain in decreasing fracture spacing and block size.The high values of s/t indicate that cross-joint formation was unlikely caused by a switch from compression to tension once a critical s/t ratio for systematic joints was reached(as hypothesized in previous studies).We proposed a new model for the formation of orthogonal joint systems where the principal stress axes locally switch during the formation of systematic fractures.The presence of ladder-shaped orthogonal joints suggests a state of effective stress withσ_(1)^(∗)≫0>σ_(2)^(∗)>σ_(3)^(∗)and whereσ_(2)^(∗)-σ_(3)^(∗)is within the range of fracture strength variability at the time of fracture.This research provides a new mechanical model for the formation of orthogonal joint systems and cuboidal blocks.
基金supported by China Geological Survey Northeastern Tarim Aeromagnetic and Aerogravity comprehensive survey project(No.12120115039401)
文摘Most of the current computing methods used to determine the magnetic field of a uniformly magnetized cuboid assume that the observation point is located in the upper half space without a source. However, such methods may generate analytical singularities for conditions of undulating terrain. Based on basic geomagnetic field theories, in this study an improved magnetic field expression is derived using an integration method of variable substitution, and all singularity problems for the entire space without a source are discussed and solved. This integration process is simpler than that of previous methods, and final integral results with a more uniform form. AT at all points in the source-flee space can be calculated without requiring coordinate transformation; thus forward modeling is also simplified. Corresponding model tests indicate that the new magnetic field expression is more correct because there is no analytical singularity and can be used with undulating terrain.
基金National 973 Basic Research Program of Chinagrant number:2010CB732600+4 种基金Major Research Equipment Fund of the Chinese Academy of Sciences and Knowledge Innovation Project of the Chinese Academy of Sciences,2008 Shenzhen Controversial Technology Innovation Research Projectsgrant number:FG200805230224AConcentration plan of innovation sources of Shenzhen-R&D projects of international cooperation on science and technologygrant number:ZYA200903260065ANatural Science Foundation of Guangdong Province,China 8478922035-X0007007
文摘Three-dimensional medical image visualization becomes an essential part for medical field, including computer aided diagnosis, surgery planning and simulation, artificial limb surgery, radiotherapy planning, and teaching etc. In this paper, marching cubes algorithm is adopted to reconstruct the 3-D images for the CT image sequence in DICOM format under theVC++6.0 and the visual package VTK platform. The relatively simple interactive operations such as rotation and transfer can be realized on the platform. Moreover, the normal vector and interior point are calculated to form the virtual clipping plane, which is then used to incise the 3-D object. Information of the virtual slice can be obtained, in the mean while the virtual slice images are displayed on the screen. The technique can realize the real time interaction extraction of virtual slice on 3-D CT image. The cuboids structured can be zoomed, moved and eircumrotated by operating mouse to incise the 3-D reconstruction object. Real time interaction can be realized by clipping the reconstruction object. The coordinates can be acquired by the mouse clicking in the 3D space, to realize the point mouse pick-up as well angle and distance interactive measurement. We can get quantitative information about 3-D images through measurement.
基金Supported by National Natural Science Foundation of China (No. 50678116)National Key Technology R&D Program of China (No. 2006BAJ13B02)Tianjin Municipal Major Project of Application Foundation and Frontal Technology Research (No. 08JCZDJC19500)
文摘A simplified method is proposed for analyzing the overpressure history of an optional point on the walls of a closed cuboid due to its internal optional point-explosion. Firstly, the overpressure histories of all nodes on the walls of a cube with a side-length of 2 m are computed under a reference-charge explosion at each node of its inner space using the LS-DYNA software, and then are collected to form a reference database. Next, with the thought of the isoparametric finite element, an interpolating algori...
文摘Cuboid fractures due to the particular bone anatomy and its protected location in the midfoot are rare, and they are usually associated with complex injuries of the foot. Clinical examination to diagnose these fractures should be detailed and the differential diagnosis, especially in the case of vague symptoms, should include the exclusion of all lateral foot pain causes. Conventional radiographs do not always reveal occult fractures, which can be under diagnosed especially in children. In this case, further investigation including magnetic resonance imaging or scintigraphy may be required. The treatment of these injuries depends on the particular fracture characteristics. Non-displaced isolated fractures of the cuboid bone can be effectively treated conservatively by immobilization and by avoiding weight bearing on the injured leg. In the case of shortening of the lateral column> 3 mm or articular displacement > 1 mm, surgical management of the fracture is mandatory in order to avoid negative biomechanical and functional consequences for the foot and adverse effects such as arthritis and stiffness as well as painful gait. In this review, an update on diagnosis and management of cuboid fractures is presented.
基金Project supported by the National Natural Science Foundation of China(Grant No.11172319)the Scientific Fund of Chinese Universities(Grant Nos.2011JS046 and 2013BH008)+1 种基金the Opening Fund of State Key Laboratory of Nonlinear Mechanics,Program for New Century Excellent Talents in University,China(Grant No.NCET-13-0552)the National Science Foundation for Post-doctoral Scientists of China(Grant No.2013M541086)
文摘Icosahedral quasicrystals are the most important and thermodynamically stable in all about 200 kinds of quasicrystals currently observed. Beyond the scope of classical elasticity, apart from a phonon displacement field, there is a phason displacement field in the elasticity of the quasicrystal, which induces an important effect on the mechanical properties of the material and makes an analytical solution difficult to obtain. In this paper, a finite element algorithm for the static elasticity of icosahedral quasicrystals is developed by transforming the elastic boundary value problem of the icosahedral quasicrystals into an equivalent variational problem. Analytical and numerical solutions for an icosahedral A1-Pd-Mn quasicrystal cuboid subjected to a uniaxial tension with different phonon-phason coupling parameters are given to verify the validity of the numerical approach. A comparison between the analytical and numerical solutions of the specimen demonstrates the accuracy and efficiency of the present algorithm. Finally, in order to reveal the fracture behavior of the icosahedral A1-Pd-Mn quasicrystal, a cracked specimen with a finite size of matter is investigated, both with and without phonon-phason coupling. Meanwhile, the geometry factors are calculated, including the stress intensity factor and the crack opening displacement for the finite-size specimen. Computational results reveal the importance of pbonon-phason coupling effect on the icosahedral A1-Pd-Mn quasicrystal. Furthermore, the finite element procedure can be used to solve more complicated boundary value problems.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11705256 and 11905272)the National Postdoctoral Program for Innovative Talents,China(Grant No.BX201700258)+1 种基金Young Scholar of CAS“Light of West China”Program for Guanghui Yang(Grant No.2018-98)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA21010202)。
文摘The dynamics of granular material discharging from a cuboid but thin hopper,including the hopper flow and granular jet,are investigated via discrete element method(DEM)simulations.The slot width is varied to study its influence on the flow.It is found the flow in the cuboid hopper has similarity with the flow in two-dimensional(2D)hopper.When the slot width is large,the flowrate is higher than the predicted value from Beverloo’s law and the velocity distribution is not Gaussian-like.For granular jet,there is a transition with varying slot width.For large slot width,there is a dense core in the jet and the variations of velocities and density are relatively small.Finally,the availability of continuum model is assessed and the results show that the performance with large slot width is better than that with small slot width.
基金National Natural Science Foundation of China,Grant/Award Number:41877272Fundamental Research Funds for the Central Universities,Grant/Award Number:2242022k30054。
文摘To systematically assess the rockburst proneness considering specimen shape,multiple groups of laboratory tests were performed on 5 rock materials in cylindrical and cuboid shapes.The linear energy storage(LES)law of both cylindrical and cuboid rock specimens under uniaxial compressive load was confirmed,and the energy storage coefficient was found to be unrelated to specimen shape.On the basis of LES law,two rockburst proneness indexes,namely the strain energy storage index(W_(et))and the potential energy of elastic strain(PES),were modified.Subsequently,the W_(et),PES,peak-strength strain energy storage index(W_(et))p,and peak-strength potential energy of elastic strain(PESp)were used to assess the rockburst proneness of the cylindrical and cuboid specimens.In addition,the fragment ejection course of specimens under test was recorded by a high-speed camera.Then,the rockburst proneness judgments obtained from the 4 indexes were compared with the qualitative data during rock destruction.The results show that,under similar stress conditions,specimen shape has an ignorable effect on the rockburst proneness as a whole.The judgment accuracy of the two modified indexes,especially that of the PESp,is favorably improved to evaluate the rockburst proneness of both cylindrical and cuboid specimens.However,misjudgment ofW_(et)^(p)and PESp may still occur in the assessment of rockburst proneness as these two indexes only consider the energy state before rock peak strength and the W_(et)^(p)is formulated in a ratio form.
文摘Traveling Salesman Problem (TSP) is one of the most widely studied real world problems of finding the shortest (minimum cost) possible route that visits each node in a given set of nodes (cities) once and then returns to origin city. The optimization of cuboid areas has potential samples that can be adapted to real world. Cuboid surfaces of buildings, rooms, furniture etc. can be given as examples. Many optimization algorithms have been used in solution of optimization problems at present. Among them, meta-heuristic algorithms come first. In this study, ant colony optimization, one of meta-heuristic methods, is applied to solve Euclidian TSP consisting of nine different sized sets of nodes randomly placed on a cuboid surface. The performance of this method is shown in tests.
基金supported by the National Natural Science Foundation of China(Grants 11872257,11572358).
文摘This paper investigates the flux-pinning-induced stress behaviors in a long superconducting slab with a central cuboid hole.The distribution of flux density is analytically derived for the critical current density of Kim model by considering the effects of the hole.The concentration of stress for both of the zero-field cooling(ZFC)and the field cooling(FC)magnetization processes are investigated through numerical simulation by using finite element method.The results indicate the potential failure mode varies with the height-width ratio and the dimensions of the hole.Different to the case of infinite hole height,the stress concentration behavior for the FC process is more critical when the dimensions of the hole are similar.The findings in this paper are useful for understanding of the degrade mechanism of superconductor in service and the design of new system.
基金Supported by the National Natural Science Foundation of China(21861044 and 21601137)the Project funded by China Postdoctoral Science Foundation(2018M633426)the Project funded by Yunnan Province Postdoctoral Science Foundation
文摘Two novel Co-based clusters with the 2-(hydroxylmethyl)pyridine(hmpH)ligand,formulated as[Co_(3)(hmp)_(6)(hmpH)]×2NO_(3)×3H_(2)O(ZTU-3)and[Co_(4)(hmp)_(4)(CH3CO_(2))2(H_(2)O)_(4)]×2NO_(3)(ZTU-4),have been successfully synthesized and structurally characterized.ZTU-3 features a triangular core geometry,while ZTU-4 exhibits a cuboidal core geometry.In addition,the magnetic properties of ZTU-3 and ZTU-4 are also all investigated.
文摘The goal of our research was to determine a coupling between information theory, geometry and multi-dimensional projections. This was accomplished after preliminary mathematics was presented to determine an alternative method for the illustration of multi-dimensional spaces. That was developed with a unique series that gives structure to integer exponents of power sets. The desired coupling is concisely illustrated in a single figure which includes three cyclic phases that are isomorphic to the three phases of Euclidian, rectangular cuboids. The series enables projections between n- and m-dimensional volumes. The associated figure also illustrates how vertical and/or horizontal symmetry breaking or symmetry emits or absorbs information.
文摘This paper introduces a novel concept of information as the logarithm of a countable subset drawn from an uncountable power set,where the countable subset represents“bits”(or mass)and the power set represents the“image”(or structure).Experimentally,the macroscopic deformation of author-related information-bearing materials is reported,showing a physical manifestation of this relationship between information and structure.Theoretically,a multidirectional projection function with floor functions creates directional cuboid volumes,connecting countable information to spatial structures.The observed conversion of information to mechanical energy associated with this deformation displays energy scales much greater than the thermodynamic limits set by Landauer’s Principle for information erasure.This significant increase indicates a potentially different and more efficient mechanism for utilizing the physical consequences of information,suggesting a potential change in the approach to energy transduction.
基金The project was funded by the EPSRC Grant(EP/101490X/1)on synthetic materials and metamaterials studies.
文摘In this paper,we investigate the possibility of using the heterogeneous materials,with cuboid metallic inclusions inside a dielectric substrate(host)to control the effective permittivity.We find that in the gigahertz range,such a material demonstrates a significantly larger permittivity compared to the pure dielectric substrate.Three principal orientations of microscale cuboid inclusions have been taken into account in this study.The highest permittivity is observed when the orientation provides the largest polarization(electric dipole moment).The detrimental side effect of the metallic inclusion,which leads to the decrease of the effective magnetic permeability,can be suppressed by the proper choice of shape and orientation of the inclusions.This choice can in fact reduce the induced current and hence maximize the permeability.The dissipative losses are shown to be negligible in the relevant range of frequencies and cuboid dimensions.
