101,670 research outputs found

    On the rigidity theorems for Lagrangian translating solitons in pseudo-Euclidean space II

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    Let uu be a smooth convex function in Rn\mathbb{R}^{n} and the graph Mβˆ‡uM_{\nabla u} of βˆ‡u\nabla u be a space-like translating soliton in pseudo-Euclidean space Rn2n\mathbb{R}^{2n}_{n} with a translating vector 1n(a1,a2,⋯ ,an;b1,b2,⋯ ,bn)\frac{1}{n}(a_{1}, a_{2}, \cdots, a_{n}; b_{1}, b_{2}, \cdots, b_{n}), then the function uu satisfies det⁑D2u=exp⁑{βˆ‘i=1nβˆ’aiβˆ‚uβˆ‚xi+βˆ‘i=1nbixi+c}onRn \det D^{2}u=\exp \left\{ \sum_{i=1}^n- a_i\frac{\partial u}{\partial x_{i}} +\sum_{i=1}^n b_ix_i+c\right\} \qquad \hbox{on}\qquad\mathbb R^n where aia_i, bib_i and cc are constants. The Bernstein type results are obtained in the course of the arguments.Comment: 9 page

    Multiple passages of light through an absorption inhomogeneity in optical imaging of turbid media

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    The multiple passages of light through an absorption inhomogeneity of finite size deep within a turbid medium is analyzed for optical imaging using the ``self-energy'' diagram. The nonlinear correction becomes more important for an inhomogeneity of a larger size and with greater contrast in absorption with respect to the host background. The nonlinear correction factor agrees well with that from Monte Carlo simulations for CW light. The correction is about 5050%-75% in near infrared for an absorption inhomogeneity with the typical optical properties found in tissues and of size of five times the transport mean free path.Comment: 3 figure

    Single-input and single-output (SISO) controller reduction based on the L1L_1-norm

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    This paper proposes a new method to solve the controller-reduction problem based on the L1L_1-norm. This method uses a reduced-order closed-loop system to deduce reduced-order controllers. The problem of obtaining the required lower-order closed-loop system was formulated as an L1L_1-norm optimization, and the conditions were provided for guaranteeing the internal stability and the existence of lower-order controllers from the obtained reduced-order closed-loop system. In addition, the particle swarm optimization and sequence linear programming were adopted to solve the resultant L1L_1-norm optimization. Two numerical examples demonstrated the effectiveness of the proposed method

    Vibration Powered Radiation of Quaking Magnetar

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    In juxtaposition with the standard model of rotation powered pulsar, the model of vibration powered magnetar undergoing quake-induced torsional Alfven vibrations in its own ultra strong magnetic field experiencing decay is considered. The presented line of argument suggests that gradual decrease of frequencies (lengthening of periods) of long-periodic pulsed radiation detected from a set of X-ray sources can be attributed to magnetic-field-decay induced energy conversion from seismic vibrations to magneto-dipole radiation of quaking magnetar.Comment: Text of talk presented at "Mini-Workshop on Pulsars", Nov. 12th, 2010; KIAA-PKU, Beijin
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