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151.
152.
153.
In the real-world application of face recognition system, owing to the difficulties of collecting samples or storage space of systems, only one sample image per person is stored in the system, which is so-called one sample per person problem. Moreover, pose and illumination have impact on recognition performance. We propose a novel pose and illumination robust algorithm for face recognition with a single training image per person to solve the above limitations. Experimental results show that the proposed algorithm is an efficient and practical approach for face recognition. 相似文献
154.
During the design process of Blu-ray disc optical pick-up (BD OPU), the optical system and the collimator lens design is especially important. This paper designs an optical system and some lenses for the BD OPU, including collimator lens, beam shaping lens for laser beam shaping, and cylinder lens for signal detecting. In this OPU, we use a triplet lens to collimate the laser beam. At the same time, we build a series of assembly jigs to make sure that each lens can be put into the OPU basement properly. At last, we get the reading spot image and S-curve photo of OPU, which can be used to read Blu-ray disc (BD). 相似文献
155.
Two vertical-cavity surface-emitting lasers(VCSELs) are mutually coupled through a partially transparent mirror (PTM) placed in the pathway. The PTM plays the role of external mirror,which controls the feedback strength and coupling strength.We numerically simulate this system by establishing a visible SIMULINK model.The results demonstrate that the anticipation synchronization is achieved and it can tolerate some extent frequency detuning.Moreover,the system shows similar chaos-pass filtering effect on unidirectionally coupled system even both VCSELs are modulated.This system allows simultaneously bidirectional secure message transmission on public channels. 相似文献
156.
Lü Baida & PAN Liuzhan . Institute of Laser Physics Chemistry Sichuan University Chengdu China . Department of Physics Luoyang Normal College Luoyang China . State Key Laboratory of Laser Technology Huazhong University of Science Technology Wuhan China Correspondence should be addressed to L Baida 《中国科学G辑(英文版)》2004,47(1):24-35
Inrecentyearsanewbranchofmodernphysicalopticscalledsingularoptics[1]hasbeendeveloped.In2002theworkinsingularopticswasextendedfrommonochromaticlighttospatiallyfullycoherentandpolychromaticlightbyGburetal.[2—4].Itwasfoundthat,whenaconverging,spatiallyfullycoherentandpolychromaticsphericalwaveisdiffractedatanaperture,anomalousspectralchangestakeplaceclosetozerosoftheintensityinthefarfield;i.e.thespectrumisredshiftedatsomepoints,blueshiftedatothers,andsplitintotwolineselsewhere.Thepredictionsofsp… 相似文献
157.
Simple Entanglement Measure for Multipartite Pure States 总被引:3,自引:0,他引:3
Feng Pan Feng Pan Feng Pan Dan Liu Guoying Lu J. P. Draayer 《International Journal of Theoretical Physics》2004,43(5):1241-1247
A simple entanglement measure for multipartite pure states is formulated based on the partial entropy of a series of reduced density matrices. Use of the proposed new measure to distinguish disentangled, partially entangled, and maximally entangled multipartite pure states is illustrated. 相似文献
158.
An economical magnetocardiogram (MCG) system is built in our laboratory. It mainly consists of a MCG data acquisition stage equipped with two high-To superconducting quantum interference device (SQUID) magnetometers, a data processing stage with digital filtering and a one-layer μ-metal magnetically shielded room in conjunction with a high-Tc SQUID based active compensation. Experimental results show that a noise level of pico-tesla in MCG profiles, which is necessary for clinical applications, may be achieved with the system. Moreover, stable and convenient operations of the system are demonstrated with simulating MCG measurements. 相似文献
159.
Dependence of bimodal size distribution on temperature and optical properties of InAs quantum dots grown on vicinal GaAs (100) substrates by using MOCVD 下载免费PDF全文
Self-assembled InAs quantum dots (QDs) are grown on vicinal GaAs (100)
substrates by using metal-organic chemical vapour deposition (MOCVD). An
abnormal temperature dependence of bimodal size distribution of InAs quantum
dots is found. As the temperature increases, the density of the small dots
grows larger while the density of the large dots turns smaller, which is
contrary to the evolution of QDs on exact GaAs (100) substrates. This trend
is explained by taking into account the presence of multiatomic steps on the
substrates. The optical properties of InAs QDs on vicinal GaAs(100)
substrates are also studied by photoluminescence (PL) . It is found that
dots on a vicinal substrate have a longer emission wavelength, a narrower PL
line width and a much larger PL intensity. 相似文献
160.
We study some typical defect problems in one-dimensional (1D) hexagonal and two-dimensional (2D) octagonal quasicrystals.
The first part of this investigation addresses in detail a uniformly moving screw dislocation in a 1D hexagonal piezoelectric
quasicrystal with point group 6mm. A general solution is derived in terms of two functions φ
1, φ
2, which satisfy wave equations, and another harmonic function φ
3. Elementary expressions for the phonon and phason displacements, strains, stresses, electric potential, electric fields and
electric displacements induced by the moving screw dislocation are then arrived at by employing the obtained general solution.
The derived solution is verified by comparison with existing solutions. Also obtained in this part of the investigation is
the total energy of the moving screw dislocation. The second part of this investigation is devoted to the study of the interaction
of a straight dislocation with a semi-infinite crack in an octagonal quasicrystal. Here the crack penetrates through the solid
along the period direction and the dislocation line is parallel to the period direction. We first derive a general solution
in terms of four analytic functions for plane strain problem in octagonal quasicrystals by means of differential operator
theory and the complex variable method. All the phonon and phason displacements and stresses can be expressed in terms of
the four analytic functions. Then we derive the exact solution for a straight dislocation near a semi-infinite crack in an
octagonal quasicrystal, and also present the phonon and phason stress intensity factors induced by the straight dislocation
and remote loads.
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