With positron annihilation radiation onedimension angular-correlation device,it ismeasured that positron annihilation radiationone dimension angular-correlation curves ofpolycrystal sodium ion conductor Na<sub>5...With positron annihilation radiation onedimension angular-correlation device,it ismeasured that positron annihilation radiationone dimension angular-correlation curves ofpolycrystal sodium ion conductor Na<sub>5</sub>Y<sub>1-x</sub>Cr<sub>x</sub>Si<sub>4</sub>O<sub>12</sub>（NYCS）system.After electronmomentum distribution curves arenormalized,linear parameters arecalculated.The parameters H,W and Sshow the change of Na<sup>+</sup> ion vacancyconcentration in NYCS series samples.Theresults show that parameters H,W and S ofone dimension angular-correlation curves ofthose samples vary greatly with Cr<sub>2</sub>O<sub>3</sub>contents.With Cr<sub>2</sub>O<sub>3</sub> content increasing,Hand S parameters increase,but W decreases,and reaches extremes at x=0.05;then withCr<sub>2</sub>0<sub>3</sub> adding continually,parameters H andS decrease gradually,parameter W increasesgradually.This shows that,in addtion toCr<sub>2</sub>O<sub>3</sub>,the conductivity has close展开更多
We are studying the motion of a random walker in generalised d-dimensional continuum with unit step length (up to 10 dimensions) and its projected one dimensional motion numerically. The motion of a random walker in l...We are studying the motion of a random walker in generalised d-dimensional continuum with unit step length (up to 10 dimensions) and its projected one dimensional motion numerically. The motion of a random walker in lattice or continuum is well studied in statistical physics but what will be the statistics of projected one dimensional motion of higher dimensional random walker is yet to be explored. Here in this paper, by addressing this particular type of problem, it shows that the projected motion is diffusive irrespective of any dimension;however, the diffusion rate is changing inversely with dimensions. As a consequence, it can be predicted that for the one dimensional projected motion of infinite dimensional random walk, the diffusion rate will be zero. This is an interesting result, at least pedagogically, which implies that though in infinite dimensions there is diffusion, its one dimensional projection is motionless. At the end of the discussion we are able to make a good comparison between projected one dimensional motion of generalised d-dimensional random walk with unit step length and pure one dimensional random walk with random step length varying uniformly between -h to h where h is a “step length renormalizing factor”.展开更多
1 Main Results Let Ω(?) R be a non-empty open subset with finite Lebesgue measure |Ω|1 and boundary Г= σΩ. We can write Ωas the union of its connected components, i.e., Ω= ∪Ij, where the open intervals Ij are ...1 Main Results Let Ω(?) R be a non-empty open subset with finite Lebesgue measure |Ω|1 and boundary Г= σΩ. We can write Ωas the union of its connected components, i.e., Ω= ∪Ij, where the open intervals Ij are pairwise disjoint and of length lj,. Since |Ω|1= sum from j=1 to ∞lj < +00, we can assume, without loss of generality, that l1 ≥l2 ≥…≥lk ≥…> 0. In this paper, we consider the eigenvalue problem of the p-Laplace operator with mixed boundary-value conditions, i.e.,展开更多
The Indo-Gangetic Plain(IGP)is one of the most seismically vulnerable areas due to its proximity to the Himalayas.Geographic information system(GIS)-based seismic characterization of the IGP was performed based on the...The Indo-Gangetic Plain(IGP)is one of the most seismically vulnerable areas due to its proximity to the Himalayas.Geographic information system(GIS)-based seismic characterization of the IGP was performed based on the degree of deformation and fractal dimension.The zone between the Main Boundary Thrust(MBT)and the Main Central Thrust(MCT)in the Himalayan Mountain Range(HMR)experienced large variations in earthquake magnitude,which were identified by Number-Size(NS)fractal modeling.The central IGP zone experienced only moderate to low mainshock levels.Fractal analysis of earthquake epicenters reveals a large scattering of earthquake epicenters in the HMR and central IGP zones.Similarly,the fault fractal analysis identifies the HMR,central IGP,and south-western IGP zones as having more faults.Overall,the seismicity of the study region is strong in the central IGP,south-western IGP,and HMR zones,moderate in the western and southern IGP,and low in the northern,eastern,and south-eastern IGP zones.展开更多
Understanding the mechanical properties and multiscale failure mechanism of frozen soft rock is an important prerequisite for the construction safety of tunnels,artificially frozen ground and other infrastructure in c...Understanding the mechanical properties and multiscale failure mechanism of frozen soft rock is an important prerequisite for the construction safety of tunnels,artificially frozen ground and other infrastructure in cold regions.In this study,the triaxial compression test are performed on mudstone in the weakly cemented soft rock strata in the mining area of western China,and the mechanical characteristics and failure mechanism of weakly cemented mudstone are systematically investigated under the combined action of freezing and loading.Furthermore,the quantitative relationship between the microstructural parameters and the macroscopic strength and deformation parameters is established based on fractal theory.Thus,the failure mechanism of frozen weakly cemented mudstone is revealed on both micro- and macro-scales.The results show that temperature and confining pressure significantly affects the elastic modulus and peak strength of weakly cemented mudstone.With decreasing temperature,the compressive strength increases,while the corresponding peak strain decreases gradually.On the deformation curve,the plastic deformation stage is shortened,and the brittle fracture feature at the post-peak stage is more prominent,and the elastic modulus correspondingly increases with decreasing temperature.Under low-temperature conditions,most of the weakly cemented mudstone undergoes microscopic shear failure along the main fracture surface.The micro-fracture morphology characteristics of weakly cemented mudstone under different temperatures are quantified via the fractal dimension,and an approximately exponential relationship can be obtained among the fractal dimension and the temperature,compressive strength and elastic modulus.展开更多
In this paper, the initial boundary value problem of a class of nonlinear generalized Kolmogorov-Petrovlkii-Piskunov equations is studied. The existence and uniqueness of the solution and the bounded absorption set ar...In this paper, the initial boundary value problem of a class of nonlinear generalized Kolmogorov-Petrovlkii-Piskunov equations is studied. The existence and uniqueness of the solution and the bounded absorption set are proved by the prior estimation and the Galerkin finite element method, thus the existence of the global attractor is proved and the upper bound estimate of the global attractor is obtained.展开更多
This paper presents a new dimension reduction strategy for medium and large-scale linear programming problems. The proposed method uses a subset of the original constraints and combines two algorithms: the weighted av...This paper presents a new dimension reduction strategy for medium and large-scale linear programming problems. The proposed method uses a subset of the original constraints and combines two algorithms: the weighted average and the cosine simplex algorithm. The first approach identifies binding constraints by using the weighted average of each constraint, whereas the second algorithm is based on the cosine similarity between the vector of the objective function and the constraints. These two approaches are complementary, and when used together, they locate the essential subset of initial constraints required for solving medium and large-scale linear programming problems. After reducing the dimension of the linear programming problem using the subset of the essential constraints, the solution method can be chosen from any suitable method for linear programming. The proposed approach was applied to a set of well-known benchmarks as well as more than 2000 random medium and large-scale linear programming problems. The results are promising, indicating that the new approach contributes to the reduction of both the size of the problems and the total number of iterations required. A tree-based classification model also confirmed the need for combining the two approaches. A detailed numerical example, the general numerical results, and the statistical analysis for the decision tree procedure are presented.展开更多
We develop a cosmological model in a physical background scenario of four time and four space dimensions ((4+4)-dimensions or (4+4)-universe). We show that in this framework the (1+3)-universe is deeply connected with...We develop a cosmological model in a physical background scenario of four time and four space dimensions ((4+4)-dimensions or (4+4)-universe). We show that in this framework the (1+3)-universe is deeply connected with the (3+1)-universe. We argue that this means that in the (4+4)-universe there exists a duality relation between the (1+3)-universe and the (3+1)-universe.展开更多
Lyapunov exponents,Lyapunov dimension and general dimensions have been determined from a time series of electrodynamic cone loudspeaker.It is found that a low-dimensional chaotic at tractor has one positive largest ex...Lyapunov exponents,Lyapunov dimension and general dimensions have been determined from a time series of electrodynamic cone loudspeaker.It is found that a low-dimensional chaotic at tractor has one positive largest exponent,and the Lyapunov dimension is in concordance with the Hausdorff dimension which calculated by general correlation integrated method.展开更多
Large deposits of cement raw material and resources like limestone, gypsum and shales/clays found from the Koh Sulaiman area of South Punjab (Saraikistan) and Balochistan Provinces, Pakistan. The installation of cemen...Large deposits of cement raw material and resources like limestone, gypsum and shales/clays found from the Koh Sulaiman area of South Punjab (Saraikistan) and Balochistan Provinces, Pakistan. The installation of cement industries especially in South Punjab/Saraikistan Province due to close occurrences of resources should develop the area and increase the export. The Koh Sulaiman regions of South Punjab (Saraikistan) have huge gypsum deposits which deserve for further exploitation. Pakistan is agricultural country and fertility of cultivated lands is vital. Fertilizer resources like phosphate deposits are moderate but the deposits of phosphate and potash bearing rocks are very vast and need their further explorations and exploitation in the Indus Basin. Pakistan has very large construction, dimension and decor stone deposits like limestone, marble, dolomite and igneous rocks like granite, dolerite, serpentine, etc. which needs further exploitation for the development of the areas and increase export. Pakistan is spending a lot of earnings for importing glass, glass wares, pottery, clay, etc. while Pakistan has these resources which needs exploitation of own resources. The best structures and geotectonic elements like the Northern and Western Indus Sutures and Karakoram Suture and Indus placers which are rich in gemstones and jewelry resources. To increase gems and jewelry export, these industries requires reduction in gemstones smuggling and encouragement for gem appraisal and jewelry industry at high level for value addition. In short, Pakistan is rich in natural resources but poor in development. Try should be made to develop and export the own mineral commodities like cement, gypsum, marble, gemstones and jewelry.展开更多
An one-dimension al three-tile quasilattice model is introduced.A multifractal spectral behavior has been found analytically and confirmed by the numerical simulation.The renormalixaction-group method has been used to...An one-dimension al three-tile quasilattice model is introduced.A multifractal spectral behavior has been found analytically and confirmed by the numerical simulation.The renormalixaction-group method has been used to study the asymptotical behavior of the spectrum,a pseudo-seven-cycle of trace map is found.展开更多
Scatterers often exhibit aspect or frequency dependence which affects the micro-Doppler shift in scattering response.For cone-cylinder targets, sliding-type scatterers which slide on the edge discontinuity with the ch...Scatterers often exhibit aspect or frequency dependence which affects the micro-Doppler shift in scattering response.For cone-cylinder targets, sliding-type scatterers which slide on the edge discontinuity with the change of the incident angle are the most dominant nonideal scattering models. A method is proposed to discriminate among the scatterers on the cone-cylinder target based on the deviation degree of micro-Doppler from sinusoid.By extracting the amplitude and initial phase, the micro-Doppler is estimated as sinusoid. Then the deviation degree is evaluated by the error between the extracted sinusoidal micro-Doppler and the actual micro-Doppler curve. Threshold for the classification is determined with the simulation data. After classification, the micro-Doppler features of sliding-type scatterers are exploited to estimate the target dimensions. The influence of parameters errors and noise on estimation of target dimensions is also illustrated with the simulation data.展开更多
Recent developments in in situ nuclear magnetic resonance(NMR)spectroscopy under extreme conditions have led to the observation of a wide variety of physical phenomena that are not accessible with standard high-pressu...Recent developments in in situ nuclear magnetic resonance(NMR)spectroscopy under extreme conditions have led to the observation of a wide variety of physical phenomena that are not accessible with standard high-pressure experimental probes.However,inherent di-or quadrupolar line broadening in diamond anvil cell(DAC)-based NMR experiments often limits detailed investigation of local atomic structures,especially if different phases or local environments coexist.Here,we describe our progress in the development of high-resolutionNMRexperiments in DACs using one-and two-dimensional homonuclear decoupling experiments at pressures up to the megabar regime.Using this technique,spectral resolutions of the order of 1 ppm and below have been achieved,enabling high-pressure structural analysis.Several examples are presented that demonstrate the wide applicability of this method for extreme conditions research.展开更多
Various methods for evaluating the fractal curves were reviewed and simulated on computer. It is shown box-counting and power spectrum methods generally give poor measuring results, while yard and variation methods co...Various methods for evaluating the fractal curves were reviewed and simulated on computer. It is shown box-counting and power spectrum methods generally give poor measuring results, while yard and variation methods could obtain good results. However,owing to multiple influencing factors, further study needs to be done before widespread application of variation method. In order to improve the measuring accuracy of yard method, a new method has been propoed to measure the fractal dimension by changing the instrumental resolutions.展开更多
This paper presents a strategy for computation of super-convergent solutions of multi-dimensional problems in the finite element method(FEM) by recursive application of the one-dimensional(1D) element energy projectio...This paper presents a strategy for computation of super-convergent solutions of multi-dimensional problems in the finite element method(FEM) by recursive application of the one-dimensional(1D) element energy projection(EEP) technique. The main idea is to conceptually treat multi-dimensional problems as generalized 1D problems,based on which the concepts of generalized 1D FEM and its consequent EEP formulae have been developed in a unified manner. Equipped with these concepts, multi-dimensional problems can be recursively discretized in one dimension at each step, until a fully discretized standard finite element(FE) model is reached. This conceptual dimension-bydimension(D-by-D) discretization procedure is entirely equivalent to a full FE discretization. As a reverseD-by-D recovery procedure, by using the unified EEP formulae together with proper extraction of the generalized nodal solutions, super-convergent displacements and first derivatives for two-dimensional(2D) and three-dimensional(3D) problems can be obtained over the domain. Numerical examples of 3D Poisson's equation and elasticity problem are given to verify the feasibility and effectiveness of the proposed strategy.展开更多
Laser–plasma instability(LPI)is one of the main obstacles to achieving predictable and reproducible fusion at high gain through laser-driven inertial confinement fusion(ICF).In this paper,for the first time,we show a...Laser–plasma instability(LPI)is one of the main obstacles to achieving predictable and reproducible fusion at high gain through laser-driven inertial confinement fusion(ICF).In this paper,for the first time,we show analytically and confirm with three-dimensional particle-incell simulations that angular incoherence provides suppression of the instability growth rate that is additional to and much stronger than that provided by the well-known temporal and spatial incoherence usually used in ICF studies.For the model used in our calculations,the maximum field ratio between the stimulated Raman scattering and the driving pulses drops from 0.2 for a Laguerre–Gaussian pulse with a single nonzero topological charge to 0.05 for a super light spring with an angular momentum spread and random relative phases.In particular,angular incoherence does not introduce extra undesirable hot electrons.This provides a novel method for suppressing LPI by using light with an angular momentum spread and paves the way towards a low-LPI laser system for inertial fusion energy with a super light spring of incoherence in all dimensions of time,space,and angle,and may open the door to the use of longer-wavelength lasers for inertial fusion energy.展开更多
The structural evolutions of the organisms during the development of billions of years endow them with remarkable thermal-regulation properties,which have significance to their survival against the outer versatile env...The structural evolutions of the organisms during the development of billions of years endow them with remarkable thermal-regulation properties,which have significance to their survival against the outer versatile environment.Inspired by the nature,there have been extensive researches to develop thermoregulating materials by mimicking and utilizing the advantages from the natural organisms.In this review,the latest advances in thermal regulation of bioinspired microstructures are summarized,classifying the researches from dimension.The representative materials are described with emphasis on the relationship between the structural features and the corresponding thermal-regulation functions.For one-dimensional materials,wild silkworm cocoon fibers have been involved,and the reasons for unique optical phenomena have been discussed.Pyramid cone structure,grating and multilayer film structure are chosen as typical examples of two-dimensional bionics.The excellent thermal performance of the three-dimensional network frame structures is the focus.Finally,a summary and outlook are given.展开更多
We propose a one-dimensional optical lattice model to simulate and explore two-dimensional topological phases with ultracold atoms,considering the phases of the hopping strengths as an extra dimension.It is shown that...We propose a one-dimensional optical lattice model to simulate and explore two-dimensional topological phases with ultracold atoms,considering the phases of the hopping strengths as an extra dimension.It is shown that the model exhibits nontrivial phases,and corresponding two chiral-edge states.Moreover,we demonstrate the connections between changes in the topological invariants and the Dirac points.Furthermore,the topological order detected by the particle pumping approach in cold atoms is also investigated.The results obtained here provide a feasible and flexible method of simulating and exploring high-dimensional topological phases in lowdimension systems via the controllable phase of the hopping strength.展开更多
The precision of the kernel independent component analysis( KICA) algorithm depends on the type and parameter values of kernel function. Therefore,it's of great significance to study the choice method of KICA'...The precision of the kernel independent component analysis( KICA) algorithm depends on the type and parameter values of kernel function. Therefore,it's of great significance to study the choice method of KICA's kernel parameters for improving its feature dimension reduction result. In this paper, a fitness function was established by use of the ideal of Fisher discrimination function firstly. Then the global optimal solution of fitness function was searched by particle swarm optimization( PSO) algorithm and a multi-state information dimension reduction algorithm based on PSO-KICA was established. Finally,the validity of this algorithm to enhance the precision of feature dimension reduction has been proven.展开更多
文摘With positron annihilation radiation onedimension angular-correlation device,it ismeasured that positron annihilation radiationone dimension angular-correlation curves ofpolycrystal sodium ion conductor Na<sub>5</sub>Y<sub>1-x</sub>Cr<sub>x</sub>Si<sub>4</sub>O<sub>12</sub>（NYCS）system.After electronmomentum distribution curves arenormalized,linear parameters arecalculated.The parameters H,W and Sshow the change of Na<sup>+</sup> ion vacancyconcentration in NYCS series samples.Theresults show that parameters H,W and S ofone dimension angular-correlation curves ofthose samples vary greatly with Cr<sub>2</sub>O<sub>3</sub>contents.With Cr<sub>2</sub>O<sub>3</sub> content increasing,Hand S parameters increase,but W decreases,and reaches extremes at x=0.05;then withCr<sub>2</sub>0<sub>3</sub> adding continually,parameters H andS decrease gradually,parameter W increasesgradually.This shows that,in addtion toCr<sub>2</sub>O<sub>3</sub>,the conductivity has close
文摘We are studying the motion of a random walker in generalised d-dimensional continuum with unit step length (up to 10 dimensions) and its projected one dimensional motion numerically. The motion of a random walker in lattice or continuum is well studied in statistical physics but what will be the statistics of projected one dimensional motion of higher dimensional random walker is yet to be explored. Here in this paper, by addressing this particular type of problem, it shows that the projected motion is diffusive irrespective of any dimension;however, the diffusion rate is changing inversely with dimensions. As a consequence, it can be predicted that for the one dimensional projected motion of infinite dimensional random walk, the diffusion rate will be zero. This is an interesting result, at least pedagogically, which implies that though in infinite dimensions there is diffusion, its one dimensional projection is motionless. At the end of the discussion we are able to make a good comparison between projected one dimensional motion of generalised d-dimensional random walk with unit step length and pure one dimensional random walk with random step length varying uniformly between -h to h where h is a “step length renormalizing factor”.
基金the NNSP (10025107) of China and the 973 Projects.
文摘1 Main Results Let Ω(?) R be a non-empty open subset with finite Lebesgue measure |Ω|1 and boundary Г= σΩ. We can write Ωas the union of its connected components, i.e., Ω= ∪Ij, where the open intervals Ij are pairwise disjoint and of length lj,. Since |Ω|1= sum from j=1 to ∞lj < +00, we can assume, without loss of generality, that l1 ≥l2 ≥…≥lk ≥…> 0. In this paper, we consider the eigenvalue problem of the p-Laplace operator with mixed boundary-value conditions, i.e.,
文摘The Indo-Gangetic Plain(IGP)is one of the most seismically vulnerable areas due to its proximity to the Himalayas.Geographic information system(GIS)-based seismic characterization of the IGP was performed based on the degree of deformation and fractal dimension.The zone between the Main Boundary Thrust(MBT)and the Main Central Thrust(MCT)in the Himalayan Mountain Range(HMR)experienced large variations in earthquake magnitude,which were identified by Number-Size(NS)fractal modeling.The central IGP zone experienced only moderate to low mainshock levels.Fractal analysis of earthquake epicenters reveals a large scattering of earthquake epicenters in the HMR and central IGP zones.Similarly,the fault fractal analysis identifies the HMR,central IGP,and south-western IGP zones as having more faults.Overall,the seismicity of the study region is strong in the central IGP,south-western IGP,and HMR zones,moderate in the western and southern IGP,and low in the northern,eastern,and south-eastern IGP zones.
基金funding support from Natural Science Foundation of Shandong Province(Grant No.ZR2021QE187).
文摘Understanding the mechanical properties and multiscale failure mechanism of frozen soft rock is an important prerequisite for the construction safety of tunnels,artificially frozen ground and other infrastructure in cold regions.In this study,the triaxial compression test are performed on mudstone in the weakly cemented soft rock strata in the mining area of western China,and the mechanical characteristics and failure mechanism of weakly cemented mudstone are systematically investigated under the combined action of freezing and loading.Furthermore,the quantitative relationship between the microstructural parameters and the macroscopic strength and deformation parameters is established based on fractal theory.Thus,the failure mechanism of frozen weakly cemented mudstone is revealed on both micro- and macro-scales.The results show that temperature and confining pressure significantly affects the elastic modulus and peak strength of weakly cemented mudstone.With decreasing temperature,the compressive strength increases,while the corresponding peak strain decreases gradually.On the deformation curve,the plastic deformation stage is shortened,and the brittle fracture feature at the post-peak stage is more prominent,and the elastic modulus correspondingly increases with decreasing temperature.Under low-temperature conditions,most of the weakly cemented mudstone undergoes microscopic shear failure along the main fracture surface.The micro-fracture morphology characteristics of weakly cemented mudstone under different temperatures are quantified via the fractal dimension,and an approximately exponential relationship can be obtained among the fractal dimension and the temperature,compressive strength and elastic modulus.
文摘In this paper, the initial boundary value problem of a class of nonlinear generalized Kolmogorov-Petrovlkii-Piskunov equations is studied. The existence and uniqueness of the solution and the bounded absorption set are proved by the prior estimation and the Galerkin finite element method, thus the existence of the global attractor is proved and the upper bound estimate of the global attractor is obtained.
文摘This paper presents a new dimension reduction strategy for medium and large-scale linear programming problems. The proposed method uses a subset of the original constraints and combines two algorithms: the weighted average and the cosine simplex algorithm. The first approach identifies binding constraints by using the weighted average of each constraint, whereas the second algorithm is based on the cosine similarity between the vector of the objective function and the constraints. These two approaches are complementary, and when used together, they locate the essential subset of initial constraints required for solving medium and large-scale linear programming problems. After reducing the dimension of the linear programming problem using the subset of the essential constraints, the solution method can be chosen from any suitable method for linear programming. The proposed approach was applied to a set of well-known benchmarks as well as more than 2000 random medium and large-scale linear programming problems. The results are promising, indicating that the new approach contributes to the reduction of both the size of the problems and the total number of iterations required. A tree-based classification model also confirmed the need for combining the two approaches. A detailed numerical example, the general numerical results, and the statistical analysis for the decision tree procedure are presented.
文摘We develop a cosmological model in a physical background scenario of four time and four space dimensions ((4+4)-dimensions or (4+4)-universe). We show that in this framework the (1+3)-universe is deeply connected with the (3+1)-universe. We argue that this means that in the (4+4)-universe there exists a duality relation between the (1+3)-universe and the (3+1)-universe.
文摘Lyapunov exponents,Lyapunov dimension and general dimensions have been determined from a time series of electrodynamic cone loudspeaker.It is found that a low-dimensional chaotic at tractor has one positive largest exponent,and the Lyapunov dimension is in concordance with the Hausdorff dimension which calculated by general correlation integrated method.
文摘Large deposits of cement raw material and resources like limestone, gypsum and shales/clays found from the Koh Sulaiman area of South Punjab (Saraikistan) and Balochistan Provinces, Pakistan. The installation of cement industries especially in South Punjab/Saraikistan Province due to close occurrences of resources should develop the area and increase the export. The Koh Sulaiman regions of South Punjab (Saraikistan) have huge gypsum deposits which deserve for further exploitation. Pakistan is agricultural country and fertility of cultivated lands is vital. Fertilizer resources like phosphate deposits are moderate but the deposits of phosphate and potash bearing rocks are very vast and need their further explorations and exploitation in the Indus Basin. Pakistan has very large construction, dimension and decor stone deposits like limestone, marble, dolomite and igneous rocks like granite, dolerite, serpentine, etc. which needs further exploitation for the development of the areas and increase export. Pakistan is spending a lot of earnings for importing glass, glass wares, pottery, clay, etc. while Pakistan has these resources which needs exploitation of own resources. The best structures and geotectonic elements like the Northern and Western Indus Sutures and Karakoram Suture and Indus placers which are rich in gemstones and jewelry resources. To increase gems and jewelry export, these industries requires reduction in gemstones smuggling and encouragement for gem appraisal and jewelry industry at high level for value addition. In short, Pakistan is rich in natural resources but poor in development. Try should be made to develop and export the own mineral commodities like cement, gypsum, marble, gemstones and jewelry.
基金Supported by the National Natural Science Foundation of China.
文摘An one-dimension al three-tile quasilattice model is introduced.A multifractal spectral behavior has been found analytically and confirmed by the numerical simulation.The renormalixaction-group method has been used to study the asymptotical behavior of the spectrum,a pseudo-seven-cycle of trace map is found.
基金supported by the National Natural Science Foundation of China(61271442)
文摘Scatterers often exhibit aspect or frequency dependence which affects the micro-Doppler shift in scattering response.For cone-cylinder targets, sliding-type scatterers which slide on the edge discontinuity with the change of the incident angle are the most dominant nonideal scattering models. A method is proposed to discriminate among the scatterers on the cone-cylinder target based on the deviation degree of micro-Doppler from sinusoid.By extracting the amplitude and initial phase, the micro-Doppler is estimated as sinusoid. Then the deviation degree is evaluated by the error between the extracted sinusoidal micro-Doppler and the actual micro-Doppler curve. Threshold for the classification is determined with the simulation data. After classification, the micro-Doppler features of sliding-type scatterers are exploited to estimate the target dimensions. The influence of parameters errors and noise on estimation of target dimensions is also illustrated with the simulation data.
基金We thank the German Research Foundation(Deutsche Forschungsgemeinschaft,DFG,Project Nos.DU954/11-1,DU393/13-1,DU393/9-2,andME5206/3-1)the Federal Ministry of Education and Research,Germany(BMBF,Grant No.05K19WC1)for financial support.T.M.thanks the Center for High Pressure Science and Technology Advanced Research for financial support.F.T.thanks the Swedish Research Council(VR)(Grant No.2019-05600)D.L.thanks the Alexander von Humboldt Foundation for financial support.N.D.thanks the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University(Faculty Grant SFO-Mat-LiU No.200900971).
文摘Recent developments in in situ nuclear magnetic resonance(NMR)spectroscopy under extreme conditions have led to the observation of a wide variety of physical phenomena that are not accessible with standard high-pressure experimental probes.However,inherent di-or quadrupolar line broadening in diamond anvil cell(DAC)-based NMR experiments often limits detailed investigation of local atomic structures,especially if different phases or local environments coexist.Here,we describe our progress in the development of high-resolutionNMRexperiments in DACs using one-and two-dimensional homonuclear decoupling experiments at pressures up to the megabar regime.Using this technique,spectral resolutions of the order of 1 ppm and below have been achieved,enabling high-pressure structural analysis.Several examples are presented that demonstrate the wide applicability of this method for extreme conditions research.
文摘Various methods for evaluating the fractal curves were reviewed and simulated on computer. It is shown box-counting and power spectrum methods generally give poor measuring results, while yard and variation methods could obtain good results. However,owing to multiple influencing factors, further study needs to be done before widespread application of variation method. In order to improve the measuring accuracy of yard method, a new method has been propoed to measure the fractal dimension by changing the instrumental resolutions.
基金supported by the National Natural Science Foundation of China(Nos.51378293 and 51078199)
文摘This paper presents a strategy for computation of super-convergent solutions of multi-dimensional problems in the finite element method(FEM) by recursive application of the one-dimensional(1D) element energy projection(EEP) technique. The main idea is to conceptually treat multi-dimensional problems as generalized 1D problems,based on which the concepts of generalized 1D FEM and its consequent EEP formulae have been developed in a unified manner. Equipped with these concepts, multi-dimensional problems can be recursively discretized in one dimension at each step, until a fully discretized standard finite element(FE) model is reached. This conceptual dimension-bydimension(D-by-D) discretization procedure is entirely equivalent to a full FE discretization. As a reverseD-by-D recovery procedure, by using the unified EEP formulae together with proper extraction of the generalized nodal solutions, super-convergent displacements and first derivatives for two-dimensional(2D) and three-dimensional(3D) problems can be obtained over the domain. Numerical examples of 3D Poisson's equation and elasticity problem are given to verify the feasibility and effectiveness of the proposed strategy.
基金This work was supported by the National Key R&D Program of China(Grant No.2018YFA0404803)the National Natural Science Foundation of China(Grant Nos.11922515,11935008,11335013,and 12035002).
文摘Laser–plasma instability(LPI)is one of the main obstacles to achieving predictable and reproducible fusion at high gain through laser-driven inertial confinement fusion(ICF).In this paper,for the first time,we show analytically and confirm with three-dimensional particle-incell simulations that angular incoherence provides suppression of the instability growth rate that is additional to and much stronger than that provided by the well-known temporal and spatial incoherence usually used in ICF studies.For the model used in our calculations,the maximum field ratio between the stimulated Raman scattering and the driving pulses drops from 0.2 for a Laguerre–Gaussian pulse with a single nonzero topological charge to 0.05 for a super light spring with an angular momentum spread and random relative phases.In particular,angular incoherence does not introduce extra undesirable hot electrons.This provides a novel method for suppressing LPI by using light with an angular momentum spread and paves the way towards a low-LPI laser system for inertial fusion energy with a super light spring of incoherence in all dimensions of time,space,and angle,and may open the door to the use of longer-wavelength lasers for inertial fusion energy.
基金supported by the Top Young Talents of Ten Thousand Talents Plan,National Natural Science Foundation of China(51971133,51801121,51902200,and 52072241)the Shanghai Science and Technology Committee(19JC1410400,19ZR1425100).
文摘The structural evolutions of the organisms during the development of billions of years endow them with remarkable thermal-regulation properties,which have significance to their survival against the outer versatile environment.Inspired by the nature,there have been extensive researches to develop thermoregulating materials by mimicking and utilizing the advantages from the natural organisms.In this review,the latest advances in thermal regulation of bioinspired microstructures are summarized,classifying the researches from dimension.The representative materials are described with emphasis on the relationship between the structural features and the corresponding thermal-regulation functions.For one-dimensional materials,wild silkworm cocoon fibers have been involved,and the reasons for unique optical phenomena have been discussed.Pyramid cone structure,grating and multilayer film structure are chosen as typical examples of two-dimensional bionics.The excellent thermal performance of the three-dimensional network frame structures is the focus.Finally,a summary and outlook are given.
基金the National Natural Science Foundation of China(Grant No.11874190)。
文摘We propose a one-dimensional optical lattice model to simulate and explore two-dimensional topological phases with ultracold atoms,considering the phases of the hopping strengths as an extra dimension.It is shown that the model exhibits nontrivial phases,and corresponding two chiral-edge states.Moreover,we demonstrate the connections between changes in the topological invariants and the Dirac points.Furthermore,the topological order detected by the particle pumping approach in cold atoms is also investigated.The results obtained here provide a feasible and flexible method of simulating and exploring high-dimensional topological phases in lowdimension systems via the controllable phase of the hopping strength.
文摘The precision of the kernel independent component analysis( KICA) algorithm depends on the type and parameter values of kernel function. Therefore,it's of great significance to study the choice method of KICA's kernel parameters for improving its feature dimension reduction result. In this paper, a fitness function was established by use of the ideal of Fisher discrimination function firstly. Then the global optimal solution of fitness function was searched by particle swarm optimization( PSO) algorithm and a multi-state information dimension reduction algorithm based on PSO-KICA was established. Finally,the validity of this algorithm to enhance the precision of feature dimension reduction has been proven.
