Based on the high order nonlinear and dispersive wave equation with a dissipative term, a numerical model for nonlinear waves is developed, It is suitable to calculate wave propagation in water areas with an arbitrari...Based on the high order nonlinear and dispersive wave equation with a dissipative term, a numerical model for nonlinear waves is developed, It is suitable to calculate wave propagation in water areas with an arbitrarily varying bottom slope and a relative depth h/L(0)less than or equal to1. By the application of the completely implicit stagger grid and central difference algorithm, discrete governing equations are obtained. Although the central difference algorithm of second-order accuracy both in time and space domains is used to yield the difference equations, the order of truncation error in the difference equation is the same as that of the third-order derivatives of the Boussinesq equation. In this paper, the correction to the first-order derivative is made, and the accuracy of the difference equation is improved. The verifications of accuracy show that the results of the numerical model are in good agreement with those of analytical Solutions and physical models.展开更多
An approximation approach is proposed for realizing an arbitrarily shaped acoustic cloak.Based on the effective medium theory,the designed cloak is a discrete layered structure using homogeneous isotropic materials.Th...An approximation approach is proposed for realizing an arbitrarily shaped acoustic cloak.Based on the effective medium theory,the designed cloak is a discrete layered structure using homogeneous isotropic materials.The performance of the cloak is simulated,and the results demonstrate that the cloak possesses properties of low-reflection outside the cloak and wavefront-bending in the cloak shell.This work proves the feasibility of realizing an arbitrarily shaped acoustic cloak using normal materials.展开更多
The aim of the present study is to develop an efficient weak form quadrature element for free vibration analysis of arbitrarily shaped membranes.The arbitrarily shaped membrane is firstly mapped into a regular domain ...The aim of the present study is to develop an efficient weak form quadrature element for free vibration analysis of arbitrarily shaped membranes.The arbitrarily shaped membrane is firstly mapped into a regular domain using blending functions,and the displacement in the element is assumed as the trigonometric functions.Explicit formulations are worked out for nodes of any type and a varying number of nodes.For verifications,results are compared with exact solutions and data obtained by other numerical methods.It is demonstrated that highly accurate frequencies can be obtained with a small number of nodes by present method.展开更多
Csiszar's strong coding theorem for discrete memoryless scarce is generalized to arbitrarily varying source.We also determine the asymptotic error exponent for arbitrarily wrying source.
This paper presents a new method for solving the vibration of arbitrarily shaped membranes with ela.stical supports at points. The reaction forces of elastical supports at points are regarded as unknown external force...This paper presents a new method for solving the vibration of arbitrarily shaped membranes with ela.stical supports at points. The reaction forces of elastical supports at points are regarded as unknown external forces acting on the membranes. The exact solution of the equation of motion is given which includes terms representing the unknown reaction forces. The frequency equation is derived by the use of the linear relationship of the displacements with the reaction forces of elastical supports at points. Finally the calculating formulae of the frequency equation of circular membranes are analytically performed as examples and the inherent frequencies of circular membranes with symmetric elastical supports at two points are numerically calculated.展开更多
The capturability of an arbitrarily maneuvering target featuring speed superiority over an interceptor is analyzed for Augmented Pure Proportional Navigation(APPN)and RetroAugmented Proportional Navigation(RAPN)guidan...The capturability of an arbitrarily maneuvering target featuring speed superiority over an interceptor is analyzed for Augmented Pure Proportional Navigation(APPN)and RetroAugmented Proportional Navigation(RAPN)guidance.This paper focuses on intercepting arbitrary maneuvers to study more general interception problems.A comparative analysis of the capture region between head-on interception related to APPN and head-pursuit interception related to RAPN is proposed.The results indicate that RAPN performs better than APPN in capturability.It is concluded that increasing the target velocity,which increases the velocity ratio,significantly weakens the capturability of the interceptor,and the average acceleration and relative distance affect the location of the capture region but not its size.The analysis is based on prior knowledge of the target maneuver,which inevitably leads to deviations from actual maneuvers in practical engagement,so a deviation analysis is implemented.The effective capture region shrinks as the absolute value of acceleration deviation increases,and the RAPN has a better deviation fault tolerance compared with the APPN.The results reveal that a larger relative distance can weaken the deviation fault tolerance,and the target velocity has opposite effects on head-on and head-pursuit interception.展开更多
Containing Lorentz invariance violation(LIV),a new form of the fermions dynamic equation under the background of the curved space-time of the arbitrarily accelerating black hole,is studied.Firstly,we consider the new ...Containing Lorentz invariance violation(LIV),a new form of the fermions dynamic equation under the background of the curved space-time of the arbitrarily accelerating black hole,is studied.Firstly,we consider the new form of the fermions dynamic equation with arbitrary spin containing LIV in curved space-time,and research the fermions dynamic equation with spin-1/2containing LIV.On this basis,according to the semi-classical theory and black hole quantum tunneling radiation theory,the quantum tunneling radiation of the arbitrarily accelerating Kinnersly black hole is modified correctly,and the corrected physical quantities such as black hole temperature and quantum tunneling rate are deeply discussed.The fermions dynamic equation with arbitrary spin in the arbitrarily accelerating black hole space-time and its solution are explained in detail.In order to further obtain the correction effect of the Planck scale,this article considers beyond the semi-classical theory and further obtains new expressions of the black hole temperature and tunneling radiation rate.展开更多
Through deriving expressions relating the dip-angle ( m) of the lower boundary of a layer to the acoustic velocity (υm) of the layer and other pre-determinable parameters, υm and m can be taken as simultaneously ite...Through deriving expressions relating the dip-angle ( m) of the lower boundary of a layer to the acoustic velocity (υm) of the layer and other pre-determinable parameters, υm and m can be taken as simultaneously iterative variables while solving Shah 's equations . Consequently the previous method of computing υm and m presented by ZHANG S . is improved [1] , and the accuracy of solutions increased greatly.展开更多
When the error probability is less than 2--"", the minimum compression rate(r-optimal rate) of arbitrarily varying source with a fidelity criterion is determined. Thisgeneralizes the result of Arutyunyan and...When the error probability is less than 2--"", the minimum compression rate(r-optimal rate) of arbitrarily varying source with a fidelity criterion is determined. Thisgeneralizes the result of Arutyunyan and Mekaushll] for discrete memoryless source witha fidelity criterion, and is called strong coding theorem of arbitrarily varying source witha fidelity criterion. We also determine the asymptotic error exponellt for arbitrarily varying source with a fidelity criterion. This generalizes Marton’s result in [2] for discretememoryless source with a fidelity criterion.展开更多
A simplified equation for the axisymmetry problems of ring shells of elliptical cross section under arbitrarily distributed loads in complex form has been obtained. The equation is equivalent to the exact equations wi...A simplified equation for the axisymmetry problems of ring shells of elliptical cross section under arbitrarily distributed loads in complex form has been obtained. The equation is equivalent to the exact equations within the error range of the thin shell theory, with the singularities at the points of meridional extreme values eliminated. The equivalent integral equations and the numerical solutions are given. Three examples of expansion joints, ring shells under hydro-pressure and sealing ring of semi-elliptical cross section are calculated and compared with the exact solutions and the experimental results.展开更多
Hypothesis testing for arbitrarily varying source (AVS), which is to decide between the two hypotheses for the varying behavior of the distribution of AVS, is considered in this paper. We determine the best asymptotic...Hypothesis testing for arbitrarily varying source (AVS), which is to decide between the two hypotheses for the varying behavior of the distribution of AVS, is considered in this paper. We determine the best asymptotic exponent of the second kind of error probability when the first kind of error probability is fixed. This result generalizes the well-known lemma of Stein in statistics. As a corollary, Strassen’s coding theorem for AVS is obtained.展开更多
In this article, a formulation for a hollow cylinder reinforced with an electroelastic layer is investigated. The hollow cylinder and its electro-elastic coating are under the Saint-Venant torsional loading. First, th...In this article, a formulation for a hollow cylinder reinforced with an electroelastic layer is investigated. The hollow cylinder and its electro-elastic coating are under the Saint-Venant torsional loading. First, the solution to the problem containing a Volterra-type screw dislocation is obtained by using the Fourier transform. The problem is then reduced to a set of Cauchy singular integral equations by the distributed dislocation method. Finally, several examples are presented to show the effect of the electro-elastic coating on the reduction of the stress intensity factors at the crack tips.展开更多
Small storage space for photographs in formal documents is increasingly necessary in today＇s needs for huge amounts of data communication and storage. Traditional compression algorithms do not sufficiently utilize th...Small storage space for photographs in formal documents is increasingly necessary in today＇s needs for huge amounts of data communication and storage. Traditional compression algorithms do not sufficiently utilize the distinctness of formal photographs. That is, the object is an image of the human head, and the background is in unicolor. Therefore, the compression is of low efficiency and the image after compression is still space-consuming. This paper presents an image compression algorithm based on object segmentation for practical high-efficiency applications. To achieve high coding efficiency, shape-adaptive discrete wavelet transforms are used to transformation arbitrarily shaped objects. The areas of the human head and its background are compressed separately to reduce the coding redundancy of the background. Two methods, lossless image contour coding based on differential chain, and modified set partitioning in hierarchical trees （SPIHT） algorithm of arbitrary shape, are discussed in detail. The results of experiments show that when bit per pixel （bpp）is equal to 0.078, peak signal-to-noise ratio （PSNR） of reconstructed photograph will exceed the standard of SPIHT by nearly 4dB.展开更多
Hu (1979) proposed a two-dimensional, unsteady . homogeneous coastal upwelling model with finite constant depth . Lu and Zhao (1985) extended Hu’s model by specifying a linear bottom slope. A three-dimensional .unste...Hu (1979) proposed a two-dimensional, unsteady . homogeneous coastal upwelling model with finite constant depth . Lu and Zhao (1985) extended Hu’s model by specifying a linear bottom slope. A three-dimensional .unsteady .homogeneous .coastal upwelling model on f- plane with arbitrarily linear bottom slope is suggested in this paper as an extension of Lu and Zhao’s model. The solution for such a problem has been obtained . and the properties of upwelling and horizontal current are examined .展开更多
Collision of two general geodesic particles around the Kerr–Newman black hole is studied and the center-of-mass(c.m.)energy of the non-marginally and marginally bound critical particles in the direct collision and th...Collision of two general geodesic particles around the Kerr–Newman black hole is studied and the center-of-mass(c.m.)energy of the non-marginally and marginally bound critical particles in the direct collision and the last stable orbit collision scenarios is obtained.The constraint conditions that arbitrarily high c.m.energy can be obtained for the near-horizon collision of two general geodesic particles in the extremal Kerr–Newman black hole is found,and it is noted that the charge decreases the value of the latitude in which arbitrarily high c.m.energy can occur.展开更多
We propose an efficient method to create multipartite spin entangled states in quantum dots coupled to a nano electro-mechanical resonator array.Our method,based on the interaction between electron spins confined in q...We propose an efficient method to create multipartite spin entangled states in quantum dots coupled to a nano electro-mechanical resonator array.Our method,based on the interaction between electron spins confined in quantum dots and the motion of magnetized nano electro-mechanical resonators,can enable a coherent spin-spin coupling over long distances and in principle be applied to an arbitrarily large number of electronic spins.展开更多
The effect of correlated fading reduces the performance gain in multi-antenna communications. Diversity combining is a well-known technique to reduce the effect of correlation. But still, it is an open problem to quan...The effect of correlated fading reduces the performance gain in multi-antenna communications. Diversity combining is a well-known technique to reduce the effect of correlation. But still, it is an open problem to quantify as the diversity scheme is more efficient in enhancing the security of cellular multicast network mitigating the effects of correlation. Motivated by this issue, this paper considers a secure wireless multicasting scenario through correlated cellular networks in the presence of multiple eavesdroppers. The selection combining (SC) and switch and stay combining (SSC) techniques are considered in dual arbitrarily correlated Nakagami-m fading channels. The closed-form analytical expressions for the probability of non-zero secrecy multicast capacity and the secure outage probability for multicasting are derived to understand the insight into the effects of correlation on the SC and SSC diversity schemes and to quantify which diversity scheme is more efficient in enhancing the security of correlated multicast networks. The results show that, although the diversity gain reduces the effect of correlation, the diversity gain provided by the SC diversity scheme is more significant in mitigating the effect of correlation compared to the SSC diversity scheme. Due to the selection mechanism of SC diversity, it is more sensitive to the change of SNR of the eavesdropper’s channel compared to the case of the SSC diversity scheme.展开更多
Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticit...Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticity in the vacuum bounded by them. The geometry resulting from an arbitrarily extended Casimir plates along their axis of rotation is similar to van Stockum spacetime. We observe closed timelike curves (CTC’s) forming in the exterior of the system resulting from frame dragging. The exterior geometry of this system is similar to Kerr geometry, but because of violation of ANEC, the Cauchy horizon lies outside the system unlike Kerr blackholes, giving more emphasis on whether spacetime is multiply connected at the microscopic level.展开更多
An ultra-simple and miniaturized spectrometer using an arbitrarily shaped pinhole as diffraction element reconstructs a broadband spectrum from the information of diffraction of monochromatic radiation by clever compu...An ultra-simple and miniaturized spectrometer using an arbitrarily shaped pinhole as diffraction element reconstructs a broadband spectrum from the information of diffraction of monochromatic radiation by clever computational reconstruction algorithms.This circumvents complex calibration procedures and paves the way to cost-effective on-chip spectrometers combining fast acquisition without significant loss in spectral resolution.展开更多
基金This research was financially supported by China National Key Basic Research Project "Circulation Principal and Mathematic Model" (Grant No. 1999043810) Guangdong Science and Technology Innovation Project: "Disaster Diagnoses of Sea Walls" (99B07102G)
文摘Based on the high order nonlinear and dispersive wave equation with a dissipative term, a numerical model for nonlinear waves is developed, It is suitable to calculate wave propagation in water areas with an arbitrarily varying bottom slope and a relative depth h/L(0)less than or equal to1. By the application of the completely implicit stagger grid and central difference algorithm, discrete governing equations are obtained. Although the central difference algorithm of second-order accuracy both in time and space domains is used to yield the difference equations, the order of truncation error in the difference equation is the same as that of the third-order derivatives of the Boussinesq equation. In this paper, the correction to the first-order derivative is made, and the accuracy of the difference equation is improved. The verifications of accuracy show that the results of the numerical model are in good agreement with those of analytical Solutions and physical models.
文摘An approximation approach is proposed for realizing an arbitrarily shaped acoustic cloak.Based on the effective medium theory,the designed cloak is a discrete layered structure using homogeneous isotropic materials.The performance of the cloak is simulated,and the results demonstrate that the cloak possesses properties of low-reflection outside the cloak and wavefront-bending in the cloak shell.This work proves the feasibility of realizing an arbitrarily shaped acoustic cloak using normal materials.
基金supported by the National Natural Science Foundation of China(Nos.52005256,12072154)the Natural Science Foundation of Jiangsu Province(No.BK20190394)+1 种基金the Jiangsu Post-Doctoral Research Funding Program(No.2020Z437)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘The aim of the present study is to develop an efficient weak form quadrature element for free vibration analysis of arbitrarily shaped membranes.The arbitrarily shaped membrane is firstly mapped into a regular domain using blending functions,and the displacement in the element is assumed as the trigonometric functions.Explicit formulations are worked out for nodes of any type and a varying number of nodes.For verifications,results are compared with exact solutions and data obtained by other numerical methods.It is demonstrated that highly accurate frequencies can be obtained with a small number of nodes by present method.
文摘Csiszar's strong coding theorem for discrete memoryless scarce is generalized to arbitrarily varying source.We also determine the asymptotic error exponent for arbitrarily wrying source.
文摘This paper presents a new method for solving the vibration of arbitrarily shaped membranes with ela.stical supports at points. The reaction forces of elastical supports at points are regarded as unknown external forces acting on the membranes. The exact solution of the equation of motion is given which includes terms representing the unknown reaction forces. The frequency equation is derived by the use of the linear relationship of the displacements with the reaction forces of elastical supports at points. Finally the calculating formulae of the frequency equation of circular membranes are analytically performed as examples and the inherent frequencies of circular membranes with symmetric elastical supports at two points are numerically calculated.
基金the National Natural Science Foundation of China(No.62073335)the Science Fund for Distinguished Young People in Shaanxi Province,China(No.2022JC-42)the China Postdoctoral Science Foundation(Nos.2017M613201,2019T120944 and 2020M683737).
文摘The capturability of an arbitrarily maneuvering target featuring speed superiority over an interceptor is analyzed for Augmented Pure Proportional Navigation(APPN)and RetroAugmented Proportional Navigation(RAPN)guidance.This paper focuses on intercepting arbitrary maneuvers to study more general interception problems.A comparative analysis of the capture region between head-on interception related to APPN and head-pursuit interception related to RAPN is proposed.The results indicate that RAPN performs better than APPN in capturability.It is concluded that increasing the target velocity,which increases the velocity ratio,significantly weakens the capturability of the interceptor,and the average acceleration and relative distance affect the location of the capture region but not its size.The analysis is based on prior knowledge of the target maneuver,which inevitably leads to deviations from actual maneuvers in practical engagement,so a deviation analysis is implemented.The effective capture region shrinks as the absolute value of acceleration deviation increases,and the RAPN has a better deviation fault tolerance compared with the APPN.The results reveal that a larger relative distance can weaken the deviation fault tolerance,and the target velocity has opposite effects on head-on and head-pursuit interception.
基金Supported by the National Natural Science Foundation of China under Grant No.U2031121.
文摘Containing Lorentz invariance violation(LIV),a new form of the fermions dynamic equation under the background of the curved space-time of the arbitrarily accelerating black hole,is studied.Firstly,we consider the new form of the fermions dynamic equation with arbitrary spin containing LIV in curved space-time,and research the fermions dynamic equation with spin-1/2containing LIV.On this basis,according to the semi-classical theory and black hole quantum tunneling radiation theory,the quantum tunneling radiation of the arbitrarily accelerating Kinnersly black hole is modified correctly,and the corrected physical quantities such as black hole temperature and quantum tunneling rate are deeply discussed.The fermions dynamic equation with arbitrary spin in the arbitrarily accelerating black hole space-time and its solution are explained in detail.In order to further obtain the correction effect of the Planck scale,this article considers beyond the semi-classical theory and further obtains new expressions of the black hole temperature and tunneling radiation rate.
文摘Through deriving expressions relating the dip-angle ( m) of the lower boundary of a layer to the acoustic velocity (υm) of the layer and other pre-determinable parameters, υm and m can be taken as simultaneously iterative variables while solving Shah 's equations . Consequently the previous method of computing υm and m presented by ZHANG S . is improved [1] , and the accuracy of solutions increased greatly.
文摘When the error probability is less than 2--"", the minimum compression rate(r-optimal rate) of arbitrarily varying source with a fidelity criterion is determined. Thisgeneralizes the result of Arutyunyan and Mekaushll] for discrete memoryless source witha fidelity criterion, and is called strong coding theorem of arbitrarily varying source witha fidelity criterion. We also determine the asymptotic error exponellt for arbitrarily varying source with a fidelity criterion. This generalizes Marton’s result in [2] for discretememoryless source with a fidelity criterion.
基金Project supported by the National Natural Science Foundation of China.
文摘A simplified equation for the axisymmetry problems of ring shells of elliptical cross section under arbitrarily distributed loads in complex form has been obtained. The equation is equivalent to the exact equations within the error range of the thin shell theory, with the singularities at the points of meridional extreme values eliminated. The equivalent integral equations and the numerical solutions are given. Three examples of expansion joints, ring shells under hydro-pressure and sealing ring of semi-elliptical cross section are calculated and compared with the exact solutions and the experimental results.
基金Supported by the Young Teacher Foundation of Chinese Educational Ministry and by the National Natural Science Foundation of China.
文摘Hypothesis testing for arbitrarily varying source (AVS), which is to decide between the two hypotheses for the varying behavior of the distribution of AVS, is considered in this paper. We determine the best asymptotic exponent of the second kind of error probability when the first kind of error probability is fixed. This result generalizes the well-known lemma of Stein in statistics. As a corollary, Strassen’s coding theorem for AVS is obtained.
文摘In this article, a formulation for a hollow cylinder reinforced with an electroelastic layer is investigated. The hollow cylinder and its electro-elastic coating are under the Saint-Venant torsional loading. First, the solution to the problem containing a Volterra-type screw dislocation is obtained by using the Fourier transform. The problem is then reduced to a set of Cauchy singular integral equations by the distributed dislocation method. Finally, several examples are presented to show the effect of the electro-elastic coating on the reduction of the stress intensity factors at the crack tips.
基金This work was supported by National Natural Science Foundation of China (No.60372066)
文摘Small storage space for photographs in formal documents is increasingly necessary in today＇s needs for huge amounts of data communication and storage. Traditional compression algorithms do not sufficiently utilize the distinctness of formal photographs. That is, the object is an image of the human head, and the background is in unicolor. Therefore, the compression is of low efficiency and the image after compression is still space-consuming. This paper presents an image compression algorithm based on object segmentation for practical high-efficiency applications. To achieve high coding efficiency, shape-adaptive discrete wavelet transforms are used to transformation arbitrarily shaped objects. The areas of the human head and its background are compressed separately to reduce the coding redundancy of the background. Two methods, lossless image contour coding based on differential chain, and modified set partitioning in hierarchical trees （SPIHT） algorithm of arbitrary shape, are discussed in detail. The results of experiments show that when bit per pixel （bpp）is equal to 0.078, peak signal-to-noise ratio （PSNR） of reconstructed photograph will exceed the standard of SPIHT by nearly 4dB.
文摘Hu (1979) proposed a two-dimensional, unsteady . homogeneous coastal upwelling model with finite constant depth . Lu and Zhao (1985) extended Hu’s model by specifying a linear bottom slope. A three-dimensional .unsteady .homogeneous .coastal upwelling model on f- plane with arbitrarily linear bottom slope is suggested in this paper as an extension of Lu and Zhao’s model. The solution for such a problem has been obtained . and the properties of upwelling and horizontal current are examined .
基金Supported by the Hunan Provincial Innovation Foundation for Postgraduate under Grant No CX2011B185.
文摘Collision of two general geodesic particles around the Kerr–Newman black hole is studied and the center-of-mass(c.m.)energy of the non-marginally and marginally bound critical particles in the direct collision and the last stable orbit collision scenarios is obtained.The constraint conditions that arbitrarily high c.m.energy can be obtained for the near-horizon collision of two general geodesic particles in the extremal Kerr–Newman black hole is found,and it is noted that the charge decreases the value of the latitude in which arbitrarily high c.m.energy can occur.
基金Supported by the National Basic Research Program of China under Grant No 2011CBA00200the National Natural Science Foundation of China under Grant Nos 11074243,10934006,10804104 and 10874163.
文摘We propose an efficient method to create multipartite spin entangled states in quantum dots coupled to a nano electro-mechanical resonator array.Our method,based on the interaction between electron spins confined in quantum dots and the motion of magnetized nano electro-mechanical resonators,can enable a coherent spin-spin coupling over long distances and in principle be applied to an arbitrarily large number of electronic spins.
文摘The effect of correlated fading reduces the performance gain in multi-antenna communications. Diversity combining is a well-known technique to reduce the effect of correlation. But still, it is an open problem to quantify as the diversity scheme is more efficient in enhancing the security of cellular multicast network mitigating the effects of correlation. Motivated by this issue, this paper considers a secure wireless multicasting scenario through correlated cellular networks in the presence of multiple eavesdroppers. The selection combining (SC) and switch and stay combining (SSC) techniques are considered in dual arbitrarily correlated Nakagami-m fading channels. The closed-form analytical expressions for the probability of non-zero secrecy multicast capacity and the secure outage probability for multicasting are derived to understand the insight into the effects of correlation on the SC and SSC diversity schemes and to quantify which diversity scheme is more efficient in enhancing the security of correlated multicast networks. The results show that, although the diversity gain reduces the effect of correlation, the diversity gain provided by the SC diversity scheme is more significant in mitigating the effect of correlation compared to the SSC diversity scheme. Due to the selection mechanism of SC diversity, it is more sensitive to the change of SNR of the eavesdropper’s channel compared to the case of the SSC diversity scheme.
文摘Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticity in the vacuum bounded by them. The geometry resulting from an arbitrarily extended Casimir plates along their axis of rotation is similar to van Stockum spacetime. We observe closed timelike curves (CTC’s) forming in the exterior of the system resulting from frame dragging. The exterior geometry of this system is similar to Kerr geometry, but because of violation of ANEC, the Cauchy horizon lies outside the system unlike Kerr blackholes, giving more emphasis on whether spacetime is multiply connected at the microscopic level.
文摘An ultra-simple and miniaturized spectrometer using an arbitrarily shaped pinhole as diffraction element reconstructs a broadband spectrum from the information of diffraction of monochromatic radiation by clever computational reconstruction algorithms.This circumvents complex calibration procedures and paves the way to cost-effective on-chip spectrometers combining fast acquisition without significant loss in spectral resolution.
