VNIR image simulation based on low-level flight image data

<正>A simulation method for visible and near infrared(VNIR) image is mentioned.The VNIR image obtained by low-level flight is adopted as data resource.After atmospheric correction,the ground reflectivity can be deducted.The simulation method consists of four steps:radiative transfer,spatial resolution,modulation transfer function,and noise simulation.The image of satellite-borne or high-level air-borne sensor could be generated by the simulation method from VNIR image.Experiment is carried out to test the method using an airship as platform.The resulting simulated image is compared to the image with quickbird panchromatic band.The result shows that simulation images enables one to effectively reproduce the entire process of remote sensing of the Earth.The method can be used to simulate VNIR image at satellite level at the same area and the same wavelength.     

Micromagnetic Simulation of Transfer Curve in Giant-Magnetoresistive Head

The transfer curve of the giant-magnetoresistive （GMR） magnetic head represents its most important property in applications, and it is calculated by the micromagnetic modeling of the free layer and the pinned layer in the heart of the GMR head. Affections of the bias hard magnetic layer and the anti-ferromagnetic pinning layer are modeled by effective magnetic fields. The simulated transfer curve agrees with experiment quite well, therefore the values of these effective magnetic fields can be determined by the model. A synthetic antiferromagnetic spin valve structure GMR head is also analyzed for comparison.     

Maximal symmetry and mass generation of Dirac fermions and gravitational gauge field theory in six-dimensional spacetime

The relativistic Dirac equation in four-dimensional spacetime reveals a coherent relation between the dimensions of spacetime and the degrees of freedom of fermionic spinors. A massless Dirac fermion generates new symmetries corresponding to chirality spin and charge spin as well as conformal scaling transformations. With the introduction of intrinsic W-parity, a massless Dirac fermion can be treated as a Majorana-type or Weyl-type spinor in a six-dimensional spacetime that reflects the intrinsic quantum numbers of chirality spin. A generalized Dirac equation is obtained in the six-dimensional spacetime with a maximal symmetry. Based on the framework of gravitational quantum field theory proposed in Ref. [1] with the postulate of gauge invariance and coordinate independence, we arrive at a maximally symmetric gravitational gauge field theory for the massless Dirac fermion in six-dimensional spacetime. Such a theory is governed by the local spin gauge symmetry SP(1,5) and the global Poincar′e symmetry P(1,5)= SO(1,5) P~(1,5) as well as the charge spin gauge symmetry SU(2). The theory leads to the prediction of doubly electrically charged bosons. A scalar field and conformal scaling gauge field are introduced to maintain both global and local conformal scaling symmetries. A generalized gravitational Dirac equation for the massless Dirac fermion is derived in the six-dimensional spacetime. The equations of motion for gauge fields are obtained with conserved currents in the presence of gravitational effects. The dynamics of the gauge-type gravifield as a Goldstone-like boson is shown to be governed by a conserved energy-momentum tensor, and its symmetric part provides a generalized Einstein equation of gravity. An alternative geometrical symmetry breaking mechanism for the mass generation of Dirac fermions is demonstrated.     

Urban road area recognition in ITS based on mean shift method

A color-based visual technique is described based on the mean shift image segmentation method providing relevant information for robust localization of the visible road area in Urban Intelligent Transportation System (U-ITS). The traffic image sequences are firstly trained to extract the background and then segmented into separated parts by the mean shift method as initialization, regions with the number of pixels not less than a threshold and with more uniform surfaces with the "same" color compared to their environment are filtered as recognized road area. The algorithm given in this paper can present road area recognition with arbitrary shapes, which is fit for unstructured road applications in urban cities very well.     

A passive synthetic aperture phase correction algorithm for the asymmetric twin-line array sonar

A passive synthetic aperture based on phase correction algorithm for solving the port-starboard discrimination problem in the non-aligned towed twin-line array sonar,is de- scribed.This method creates a virtual array through applying the estimated phase correction into one array of twin-line arrays.Because the synthetic virtual array is aligned with the other array in twin-line arrays,the right port-starboard discriminated results can be obtained by array processing based on the new synthetic twin-line array.The effect of proposed method has been shown by simulated and sea-trials results in towed twin-line array sonar.With low extra computational loads,the proposed method is easy to apply to the practice.     

Refractivity estimation from radar sea clutter

This paper addresses the problem of estimating lower atmospheric refractivity under the nonstandard propagation conditions frequently encountered in low altitude maritime radar applications. The vertical structure of the refractive environment is modeled by using a five-parameter model, and the horizontal structure is modeled as range-independent. The electromagnetic propagation in the troposphere is simulated by using a split-step fast Fourier transform based on parabolic approximation to the wave equation. A global search marked as a modified genetic algorithm (MGA) for the 5 environmental parameters is performed by using a genetic algorithm (GA) integrated with a simulated annealing technique. The retrieved results from simulated runs demonstrate the ability of this method to make atmospheric refractivity estimations. A comparison with the classical GA and the Bayesian Markov Chain Monte Carlo (Bayesian-MCMC) technique shows that the MGA can not only shorten the inverse time but also improve the inverse precision. For real data cases, the inversion values do not match the reference data very well. The inverted profile, however, can be used to synoptically describe the real refractive structure.     

A Fully Vectorial Effective Index Method for Accurate Dispersion Calculation of Photonic Crystal Fibres

A fully vectorial effective index method is developed for accurate dispersion calculation of photonic crystal fibres （PCFs）. In order to improve the accuracy of the model, different values for the effective core radius are used when PCFs have different fibre parameters. The accuracy of our approach is demonstrated by comparing our results with other numerical and experimental results reported in literature. It is found that the accuracy of the fully vectorial effective index method is improved and our results agree well with accurate numerical results obtained by other methods as well as the previously reported experimental data.     

Deformed Potential Energy of Super Heavy Element Z = 120 in a Generalized Liquid Drop Model

The macroscopic deformed potential energy for super-heavy elements Z=120 is determined within a generalized liquid drop model (GLDM). The shell correction is calculated with the Strutinsky method and the microscopic single particle energies are derived from the shell model in an axially deformed Woods-Saxon potential with the same quasi-molecular shape. The total potential energy of a nucleus is calculated by the macro-microscopic method as the summation of the liquid-drop energy and the Strutinsky shell correction. The theory is adopted to describe the deformed potential energies in a set of cold reactions. The neck in the quasi-molecular shape is responsible to the deep valley of the fusion barrier due to shell corrections. In the cold fusion path, the double-hump fusion barrier is predicted by the shell correction and complete fusion events may occur. The results show that some of projectile-target combinations in the entrance channel, such as ^50Ca ^252Fm→120 and 58Fe 244 pu→^302 120 , favour the fusion reaction, which can be considered as candidates for the synthesis of super heavy nuclei Z=120 and the former might be the best cold fusion reaction to produce the nucleus ^302 120among them.     

Novel method for correcting light intensity fluctuation in the TDLAS system

A novel method for online correction of light intensity fluctuation in a practical tunable diode laser ab-sorption spectroscopy(TDLAS)system with wavelength modulation is presented.The proposed method is developed according to the linear relation between peaks at multiple frequencies of sine modulation in the power spectral density of the demodulated second-harmonic(2f)signal and the incident light intensity.Those peaks are demonstrated experimentally and explained as residual power at the first-harmonic and third-harmonic frequencies after 2f demodulation of the residual amplitude modulation signal due to the limited integrating time constant of the lock-in-amplifier.This method can achieve real-time correction of light intensity fluctuations with only little calculation.It can work well in a very large range of light intensity and has great potential applications in the wavelength modulation spectroscopy system.     

Study of BESⅢ MUC offline software with cosmic-ray data

Cosmic-ray data of 90 M events have been collected and used for calibration,alignment as well as detector tuning. A special tracking algorithm for the BESⅢ muon counter is developed and verified with Monte-Carlo simulation and then further confirmed with the cosmic-ray data. The obtained strip resolutions are in good agreement with the design values. A new alignment approach for the BESⅢ muon counter is confirmed with the cosmic-ray data and proposed to be used in future analysis of experimental data.     

Acoustic performance prediction of Helmholtz resonator with conical neck

There is no accurate analytical approach for the acoustic performance prediction of Helmholtz resonator with conical neck,which has broad band acoustic attenuation performance in the low frequency range.To predict the acoustic performance of the resonator accurately,a general theory model based on the one-dimensional analysis approach with acoustic length corrections is developed.The segmentation method is used to calculate the acoustic parameters for sound propagation in conical tubes.And then,an approximate formula is deduced to give accurate correction lengths for conical tubes with difierent geometries.The deviations of the resonance frequency between the transmission loss results obtained by the general theory with acoustic lengths correction and the results from the finite element method and experiments are less than 2 Hz,which is much better than the results from one-dimensional approach without corrections.The results show that the method of acoustic length correction for the conical neck greatly improved the accuracy of the one-dimensional analysis approach,and it will be quick and accurate to predict the sound attenuation property of Helmholtz resonator with conical neck.     

A differential evolution approach for parameter extraction of solar cell from current-voltage characteristics

This letter presents an approach based on differential evolution （DE） algorithm for determining the solar cell model parameters from current-voltage （I - V） characteristics. The validity of this approach has been confirmed with experimental and simulated I - V data. It was demonstrated that the I - V curve derived from the parameters extracted by the DE approach is in good agreement with the experimental or simulated I - V data. A low objective function value as well as a high parameter precision can be obtained by the DE algorithm.     

Study of BESⅢ MUC offine software with cosmic-ray data

Cosmic-ray data of 90 M events have been collected and used for calibration,alignment as well as detector tuning. A special tracking algorithm for the BESⅢ muon counter is developed and verified with Monte-Carlo simulation and then further confirmed with the cosmic-ray data. The obtained strip resolutions are in good agreement with the design values. A new alignment approach for the BESⅢ muon counter is confirmed with the cosmic-ray data and proposed to be used in future analysis of experimental data.     

Electromagnetic dissociation of 3.7 A GeV^16O in nuclear emulsion

The electromagnetic dissociation (ED) of 3.7 A GeV {}^{16}O in nuclear emulsion is investigated with high statistics. It is found that the electromagnetically dissociated cross section increases with increasing beam energy, the charge distribution of projectile fragments is the same as the results at 60 and 200 A GeV, and the production probability of projectile fragments with charge 3≤Z≤5 is less than that of the other projectile fragments. These results can be well explained by use of Weizsacker and Williams method for calculating the ED contributions. The percentile abundance of various decay modes for ED at 3.7 A GeV is close to the result at 60 and 200 A GeV, but it is different from the result at 14.6 A GeV. The ED of 3.7 A GeV is mainly caused by the giant dipole and quadrupole resonance of E1 and E2, which can be qualitatively explained by the multiplicity distribution of projectile proton in ED. The multiplicity distribution of the α fragments in ED and nuclear events have different functional forms. This difference may be a consequence of the different reaction mechanism involved.     

Effective inhibit energetic cost in stimulated Raman shortcut-to-adiabatic passage

A shortcut to the adiabatic process is an effective method for quantum information processing.The fast and robust quantum information transfer can be implemented by this method.The energetic cost is an important measurement for the shortcut.In this paper,we investigate how to inhibit the energetic cost in stimulated Raman shortcut-to-adiabatic passage in a three-level system.The energetic cost can be manipulated by adjusting detuning of the system and the energetic cost takes the minimum with one-photon resonance condition.     

Energy and fine structure of 1s2np(n≤9) states for lithium-like systems from Z=11 to 20

A new variation method is extended to study the atomic systems with higher nuclear charges and in more highly excited states. The non-relativistic energies of 1s^2np (n≤9) states for the lithium-like systems from Z=11 to 20 are calculated using a full-core-plus-correlation method with multi-configuration interaction wavefunctions. Relativistic and mass-polarization effects on the energy are calculated as the first-order perturbation corrections. The fine structures are determined from the expectation values of spin-orbit and spin-other-orbit interaction operators in the Pauli－Breit approximation. The quantum-electrodynamics correction is also included. Our results are compared with experimental data in the literature.     

Relativistic interpretation of the nature of the nuclear tensor force

The spin-dependent nature of the nuclear tensor force is studied in detail within the relativistic HartreeFock approach. The relativistic formalism for the tensor force is supplemented with an additional Lorentz-invariant tensor formalism in the a-scalar channel, so as to take into account almost fully the nature of the tensor force brought about by the Fock diagrams in realistic nuclei. Specifically, the tensor sum rules are tested for the spin and pseudospin partners with and without nodes, to further understand the nature of the tensor force within the relativistic model. It is shown that the interference between the two components of nucleon spinors causes distinct violations of the tensor sum rules in realistic nuclei, mainly due to the opposite signs on the κ quantities of the upper and lower components, as well as the nodal difference. However, the sum rules can be precisely reproduced if the same radial wave functions are taken for the spin/pseudo-spin partners in addition to neglecting the lower/upper components,revealing clearly the nature of the tensor force.     

Energy levels of 1s~2n d(n≤9)states for lithium-like ions

The full-core plus correlation method with multi-configuration interaction wave functions is extended to the calculation of the non-relativistic energies of 1s²nd (n ≤ 9) states for the lithium isoelectronic sequence from Z = 11 to 20. Relativistic and mass-polarization effects on the energy are calculated as the first-order perturbation correction. The quantum-electrodynamics correction is also included. The fine structure splittings are determined from the expectation values of spin—orbit and spin—other-orbit interaction operators in the Pauli—Breit approximation. Combining the term energies of lowly excited states obtained with the quantum defects calculated by the single channel quantum defect theory, each of which is a smooth function of energy and approximated by a weakly varying function of energy, the ion potentials of highly excited states (n ≤ 6) are obtained with the semi-empirical iteration method. The results are compared with experimental data in the literature and found to be closely consistent with the regularity.     

Contributions of qqqq components to nucleon spin structure

The spin structure of nucleons is presented in the framework of an extended quark model which in addition to the conventional qqq structure also takes into account qqqq admixtures in the nucleon wave functions, where the qqqq components are in colored quark cluster configurations. The axial vector weak coupling constant and spin distributions for polarized nucleons as well as spin content are obtained for the lowest positive parity qqqq configurations in flavor-spin dependent interaction. In particular, the contributions of the down and strange quarks to the proton spin and the sum rule for polarized neutron are negative, in agreement with recent experiments.     

Investigation of Resistivity of Saturated Porous Media with Lattice Boltzmann Method

The lattice Boltzmann method is employed to study the electrical transport properties of saturated porous media.Electrical current flow through the porous media is simulated and the relationship between resistivity index and water saturation is derived. It is found that this kind of relation is not a straight line as described by the Archie equation with the parameter n being a constant in a log-log scale. A new equation is thus developed to formulate this relation with n being a function of porosity and water saturation. The comparisons between the results by lattice Boltzmann and by the laboratory experiments on rock samples demonstrate that this numerical method can provide an alternative way for the expensive laboratory experiments to investigate the electrical transport properties of saturated porous media and can be used to explore micro mechanisms more conveniently.