23 resultados para Calabi-Yau manifold

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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We describe a new model which is based on the concept of cognizing theory. The method identifies subsets of the data which are embedded in arbitrary oriented lower dimensional space. We definite manifold covering in biomimetic pattern recognition, and study its property. Furthermore, we propose this manifold covering algorithm based on Biomimetic Pattern Recognition. At last, the experimental results for face recognition demonstrates that the correct rejection rate of the test samples excluded in the classes of training samples is very high and effective.

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The tensile deformation and failure of polymer bonded explosives (PBXs), a particulate composite, is studied in this paper. Two HMX-based PBXs with different binder were selected for study. A diametric compression test, in which a disc-shaped specimen is loaded diametrically, was chosen to generate tensile failure in the materials. The quasi-static tensile properties and the tensile creep properties were studied by using conventional displacement transducers to measure the lateral strain along the horizontal diameter. The whole-field in-plane creep deformation was measured by using the technique of high resolution moire´ interferometry. Real time microscopic examination was conducted to monitor the process of deformation and failure of PBXs by using a scanning electron microscope equipped with a loading stage. A manifold method (MM) was used to simulate the deformation and failure of PBX samples under the diametric compression test, including the crack initiation, crack propagation and final cleavage fracture. The mechanisms of deformation and failure of PBXs under diametric compression were analyzed. The diametric compression test and the techniques developed in this research have proven to be applicable to the study of tensile properties of PBXs.

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We discuss the transversal heteroclinic cycle formed by hyperbolic periodic pointes of diffeomorphism on the differential manifold. We point out that every possible kind of transversal heteroclinic cycle has the Smalehorse property and the unstable manifolds of hyperbolic periodic points have the closure relation mutually. Therefore the strange attractor may be the closure of unstable manifolds of a countable number of hyperbolic periodic points. The Henon mapping is used as an example to show that the conclusion is reasonable.

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Static optical transmission is restudied by postulation of the optical path as the proper element in a three-dimensional Riemannian manifold (no torsion); this postulation can be applied to describe the light-medium interactive system. On the basis of the postulation, the behaviors of light transmitting through the medium with refractive index n are investigated, the investigation covering the realms of both geometrical optics and wave optics. The wave equation of light in static transmission is studied modally, the postulation being employed to derive the exact form of the optical field equation in a medium (in which the light is viewed as a single-component field). Correspondingly, the relationships concerning the conservation of optical fluid and the dynamic properties are given, and some simple applications of the theories mentioned are presented.

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By generalization of the methods presented in Part I of the study [J. Opt. Soc. Am. A 12, 600 (1994)] to the four-dimensional (4D) Riemannian manifold case, the time-dependent behavior of light transmitting in a medium is investigated theoretically by the geodesic equation and curvature in a 4D manifold. In addition, the field equation is restudied, and the 4D conserved current of the optical fluid and its conservation equation are derived and applied to deduce the time-dependent general refractive index. On this basis the forces acting on the fluid are dynamically analyzed and the self-consistency analysis is given.

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Yb:Gd2SiO5 (Yb:GSO) exhibits a large fundamental manifold splitting. Its long-wavelength emission band around 1088 nm, which has the largest emission cross section, encounters the lowest reabsorption losses caused by thermal population of the terminal laser level. As a result, low-threshold and tunable continuous-wave Yb:GSO lasers were demonstrated. A slope efficiency up to 86% and a pumping threshold as low as 127 mW were achieved for a continuous-wave Yb:GSO laser at 1092.5 nm under the pump of a high-brightness laser diode. A continuous tunability between 1000 and 1120 nm was realized with an SF14 prism as the intracavity tuning element. (c) 2006 American Institute of Physics.

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通过助熔剂固相反应法制备了5%Yb掺杂的硫氧化钇(Y2O2S)粉体。通过对其漫反射光谱和荧光光谱的测量,估算得Yb3+离子在Y2O2S晶格中的晶场分裂。由光谱数据计算得Yb3+离子的2F7/2能级在Y2O2S中的分裂值为709cm-1,适合于Yb3+离子的准三能级的激光运转。由5%Yb:Y2O2S的发射光谱拟合得出其峰位,峰高及峰宽。为了比较,相关的5%Yb:YAG的数据也被给出。

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An Ho3+-doped YAlO3 (Ho : YAP) single crystal has been grown by the Czochralski technique. The polarized absorption spectra, polarized fluorescence spectra and fluorescence decay curve of the crystal are measured at room temperature. The spectroscopic parameters are calculated based on Judd-Ofelt theory, and the effective phenomenological intensity parameters Omega(2,eff), Omega(4,eff) and Omega(6,eff) are obtained to be 2.89 x 10(-20), 2.92 x 10(-20) and 1.32 x 10(-20) cm(2), respectively. The room-temperature fluorescence lifetime of the Ho3+ 5I(7) -> I-5(8) transition is measured to be 8.1 ms. Values of the absorption and emission cross-sections with different polarizations are presented for the I-5(7) manifold, and the polarized gain cross-section curves are also provided and discussed.

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Organisms living in water are inevitably exposed to periods of hypoxia. Environmental hypoxia has been an important stressor having manifold effects on aquatic life. Many fish species have evolved behavioral, physiological, biochemical and molecular adaptations that enable them to cope with hypoxia. However, the molecular mechanisms of hypoxia tolerance in fish, remain unknown. in this study, we used suppression subtractive hybridization to examine the differential gene expression in CAB cells (Carassius auratus blastulae embryonic cells) exposed to hypoxia for 24 h. We isolated 2100 clones and identified 211 differentially expressed genes (e-value <= 5e-3; Identity > 45%). Among the genes whose expression is modified in cells, a vast majority involved in metabolism, signal transduction, cell defense, angiogenesis, cell growth and proliferation. Twelve genes encoding for ERO1-L, p53, CPO, HO-1, MKP2, PFK-2, cystatin B, GLUT1, BTG1, TGF beta 1, PGAM1, hypothetical protein F1508, were selected and identified to be hypoxia-induced using semi-quantitive RT-PCR and real-time PCR. Among the identified genes, two open reading frames (ORFs) encoding for CaBTG1 and Cacystatin B were obtained. The deduced amino acid sequence of CaBTG1 had 94.1%, 72.8%, 72.8%, 72.8%, 68.6% identity with that of DrBTG1, HsBTG1, BtBTG1, MmBTG1 and XIBTG1. Comparison of Cacystatin B with known cystatin B, the molecules exhibited 49.5 to 76.0% identity overall. These results may provide significant information for further understanding of the adaptive mechanism by which C. auratus responds to hypoxia. (c) 2008 Elsevier Inc. All rights reserved.

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We describe a new model which is based on the concept of cognizing theory. The method identifies subsets of the data which are embedded in arbitrary oriented lower dimensional space. We definite k-mean covering, and study its property. Covering subsets of points are repeatedly sampled to construct trial geometry space of various dimensions. The sampling corresponding to the feature space having the best cognition ability between a mode near zero and the rest is selected and the data points are partitioned on the basis of the best cognition ability. The repeated sampling then continues recursively on each block of the data. We propose this algorithm based on cognition models. The experimental results for face recognition demonstrate that the correct rejection rate of the test samples excluded in the classes of training samples is very high and effective.

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According to the research results reported in the past decades, it is well acknowledged that face recognition is not a trivial task. With the development of electronic devices, we are gradually revealing the secret of object recognition in the primate's visual cortex. Therefore, it is time to reconsider face recognition by using biologically inspired features. In this paper, we represent face images by utilizing the C1 units, which correspond to complex cells in the visual cortex, and pool over S1 units by using a maximum operation to reserve only the maximum response of each local area of S1 units. The new representation is termed C1 Face. Because C1 Face is naturally a third-order tensor (or a three dimensional array), we propose three-way discriminative locality alignment (TWDLA), an extension of the discriminative locality alignment, which is a top-level discriminate manifold learning-based subspace learning algorithm. TWDLA has the following advantages: (1) it takes third-order tensors as input directly so the structure information can be well preserved; (2) it models the local geometry over every modality of the input tensors so the spatial relations of input tensors within a class can be preserved; (3) it maximizes the margin between a tensor and tensors from other classes over each modality so it performs well for recognition tasks and (4) it has no under sampling problem. Extensive experiments on YALE and FERET datasets show (1) the proposed C1Face representation can better represent face images than raw pixels and (2) TWDLA can duly preserve both the local geometry and the discriminative information over every modality for recognition.

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本文从两个侧面研究了高聚物辐射交联与裂解反应。辐照高聚物分子量分布(MWD)的表征与研究。辐照高聚物MWD的研究对于辐射交联的理论与应用均有一定的意义。但由于长链支化的存在,实验准确测定MWD很困难。本文旨在运用SEC-LALLS技术来解决这一问题。为此,我们首先分析了长链支化存在下,SEC柱扩展效应对测定数据的影响,导出了一基本议程组。{c(t) = ∫g(t,τ) Co(τ)dτ (1) s(t) = ∫g(t,τ) So(τ) dτ τ = f(j)式中,t和τ均为流出时间,J为聚合物分子流体力学体积。g(t,τ)为柱扩展函数,f为标准校正函数,c(t)、s(t)分别为浓度和光散射响应函数,为可测量。Co(τ)、So(τ)分别为样品流体力学体积为f~(-1)(τ)的那部分分子的浓度及浓度与重均分子量的积。当样品为线型聚合物时,它就转化为相应的Tung和Yau方程。围绕(1)的解,我们分别利用最小二乘法拟合σ~2-T关系和Wiener滤波法解扩展方程,并用计算机模拟,检验了这些数值运算的可靠性。同时,还讨论了扩展效应、改正参数实验误差对测定结果的影响,为实际测定提供了依据。在此基础上,建议了以SEC-LALLS联用技术为核心的表征辐 照高聚物MWD的系统化方法。最后我们运用此方法初步研究了聚苯乙烯(PS)辐照后凝胶点前后溶胶性质的变化。从MWD的变化,证实反应初期参与交联反应的主要是较高分子量部分分子。低分子量分布的浓度在凝胶点前变化不大,而在凝胶点附近及以后变化较大,支化分布的变化证明这是由于小分子量部分被支化分子掩盖了的缘故。由平均分子量测点。我们观察到了凝胶点附近重均分子量变化急剧而数均分子量缓和这一现象,并求出反应G值。数学期望法在多分体系非线性交联反应中的应用。鉴于共混高聚物辐射交联技术的发展,本文运用数学期望法,系统地考虑了一类内涵很广的多组分体系的非线性交联反应。对于重均分子量及凝胶化条件,我们把它们归结为简单的矩阵运算各矩阵元的物理意义清晰、明确、可直接写出,这为不熟悉高分子反统计理论的工作者提供了方便。对于溶胶分数,我们给出了-非线性方程组,并就r元共混体系中,当初始分布皆为Flory分布时,给出了裂解和交联同时发生时的近似结果。特别地我们针对二元共混体系在实际应用中的广泛性,我们讨论了相结构,共混比的影响。最后,结合PDMS/EVA共混体系辐射交联的研究,提出了较为一般的共混体系溶胶分数分析方法。为了考察我们的方法的可靠性,文中我们还讨论了几个小分子参与的非线性交联反应体系,并与其它理论结果,作了对照,表明该方法的可靠性和直观性皆优于某些经典理论方法。

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Here we study fermionic zero modes in gauge and gravity backgrounds taking a two-dimensional compact manifold T-2 as extra dimensions. The result is that there exist massless Dirac fermions which have normalizable zero modes under quite general assumptions about these backgrounds on the bulk. Several special cases of gauge background on the torus are discussed and some simple fermionic zero modes axe obtained.