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1.
Leo Brewin 《General Relativity and Gravitation》2007,39(4):521-528
We show by an almost elementary calculation that the ADM mass of an asymptotically flat space can be computed as a limit involving
a rate of change of area of a closed 2-surface. The result is essentially the same as that given by David Brown and York (Phys.
Rev. D 55, 1977–1984 1997; Phys. Rev. D 47, 1407–1419 1993). We will prove this result in two ways, first by direct calculation from the original formula as given by
Arnowitt, Deser and Misner and second as a corollary of an earlier result by Brewin for the case of simplicial spaces. 相似文献
2.
本文阐述了语音合成专用集成电路(ASIC)的数字信号处理原理.采用波形自适应增量调制编码方法,研究并解决了语音信号的压缩与加密.用半定制标准单元CAD设计方法,CMOS工艺,完成了32K ROM 6秒语音ASIC芯片的设计. 相似文献
3.
ADM1023是由美国ANALOG DEVICES公司生产的温度监视芯片,该芯片具有高精度,双通道工作等特点,文中详细讨论了ADM1023的主要参数,结构性能,工作原理及应用设计等问题。 相似文献
4.
ITU-T与ANSI在SDH/SONET标准方面的进展,加快了世界各国在传输系统上的改造,其先进的OAM功能可用于建立具有故障保护的自愈环网络,这种自愈环包括分插复用器。ADM中的开关在其自愈环工作中起着重要作用。本文为确定其对ADM开关的需要,分析了自愈环结构2与原理,以此基础上,介绍了能明显减少硬件数量的新的空分交换方法。 相似文献
5.
Much work has focused on traffic grooming in SONET/WDM ring networks. Previous work has considered many aspects of traffic grooming, including minimizing the number of ADMs, minimizing the number of wavelengths, considering different traffic models, using different network architectures, incorporating switching capability and so on. In this work, we study traffic grooming in unidirectional ring networks with no switching capability under both uniform traffic and non-uniform traffic models to reduce electronic multiplexing costs. Based on the clustering notion, we derive a general and tighter lower bound for the number of ADMs required in traffic grooming under the uniform all-to-all traffic model. This bound reduces to special cases obtained in previous work. We also derive general, tighter, and closed form lower bounds for the number of ADMs required under two non-uniform traffic models: the distance-dependent traffic model and the non-uniform symmetric traffic model. Cost-effective multi-phase algorithms that exploit traffic characteristics are then designed and studied to efficiently groom traffic streams under different traffic models. Our numerical and simulation results show that the proposed multi-phase algorithms outperform existing traffic grooming algorithms by using a fewer number of ADMs. Our algorithms in several cases also achieve the lower bounds derived. 相似文献
6.
7.
D.D. Ganji M. Gorji M. Alipanah E. Farnad 《Numerical Methods for Partial Differential Equations》2010,26(6):1463-1475
As thermal conductivity plays an important role on fin efficiency, we tried to solve heat transfer equation with thermal conductivity as a function of temperature. In this research, some new analytical methods called homotopy perturbation method, variational iteration method, and Adomian decomposition method are introduced to be applied to solve the nonlinear heat transfer equations, and also the comparison of the applied methods (together) is shown graphically. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 相似文献
8.
In this paper we study a Hamiltonian function on the cotangent bundle of the space of Riemannian metrics on a 3-manifold M and prove the orbits of the constrained Hamiltonian dynamical system correspond to -manifolds foliated by hypersurfaces diffeomorphic to . 相似文献
9.
连续可变斜率增量调制编解码器的设计 总被引:3,自引:0,他引:3
连续可变斜率增量调制是一种性能良好的音节压扩自适应增量调制,非常适合语音信号的编解码,其硬件实现简单,抗噪声能力强,研究了连续可变斜率增量调制算法,并通过计算机模拟对系统参数及系统性能进行讨论和优化,给出了硬件实现的具体线路图,对模拟结果进行了讨论。 相似文献
10.
We give a conjecture on the lower bound of the ADM mass M by using the null energy condition. The conjecture includes a Penrose-like inequality $3M\geqslant \kappa { \mathcal A }/(4\pi )+\sqrt{{ \mathcal A }/4\pi }$ and the Penrose inequality $2M\geqslant \sqrt{{ \mathcal A }/4\pi }$ with ${ \mathcal A }$ the event horizon area and κ the surface gravity. Both the conjecture in the static spherically symmetric case and the Penrose inequality for a dynamical spacetime with spherical symmetry are proved by imposing the null energy condition. We then generalize the conjecture to a general dynamical spacetime. Our results raise a new challenge for the famous unsettled question in general relativity: in what general case can the null energy condition replace other energy conditions to ensure the Penrose inequality? 相似文献