脉冲双星PSR1913＋16—1993年诺贝尔物理学奖

本文介绍了１９９３年诺贝尔物理学获奖者，简述脉冲星和脉冲双星后，讨论ＰＳＲ１９１３＋１６对爱因斯坦广义相对论及引力辐射的可信的验证，给出了最新观测结果。     

A.Hulse,J.H.Taylor以脉冲双星PSR1913＋16的发现获1993年诺贝尔物理学奖

ＰＳＲ１９１３＋１６的发现为我们提供了一个理想的太空实验室。对它的研究使得我们第一次有机会了解强引力场的性质并与现存理论比较。它也提供了第一个对引力波存在的定量的证据。爱因斯坦的广义相对论完满地通过了这一系列实验检验。这一获得１９９３年诺贝尔物理学奖的重大成果也提供了一个基础研究与高、新技术结合，各基础研究领域相互渗透的典型例子。     

胡宁最早对双星系统的引力辐射效应作出理论预言

胡宁最早对双星系统的引力辐射效应作出理论预言关洪（中山大学物理系，广州５１０２７５）两位美国物理学家Ｊ．Ｈ．Ｔａｙｌｏｒ和Ｒ．Ａ．Ｈｕｌｓｅ由于对射电脉冲双星ＰＳＲ１９１３－１６的发现和长期观察，从所测定的周期变化率取得了引力辐射存在的第一个证据，从...     

黑洞及其在天体物理中的作用（下）

本文下篇介绍黑洞在天体物理中的作用及其观测证认情况，以类星体为代表的活动星系和Ｘ射线双星这两类典型高能天体的能源机制及各种基本特征，可以由黑洞吸积模型来成功地解释。     

关于行星运动模型疑问引发的思考

由学生的一个疑问入手, 简要分析行星运动模型与双星模型之间的关系     

引力辐射阻尼对双星轨道要素变化的影响——对过近星点时刻的影响

在文献［１］研究的基础上对双星引力辐射阻尼的效应又做了进一步研究．首先给出文献［１］的主要结果及其更正，然后利用文献［１］的结果又给出引力辐射阻尼对双星过近星点时刻的影响。结果表明，引力辐射阻尼对双星过近星点时刻不仅产生周期变化的效应，而且还产生长期变化的效应，这后者的效应使得双星过近星点时刻提前。最后利用所推出的结果对三颗双星（Ｙ Ｃｙｇ，ＰＳＲ２３０２＋２４．ＰＳＲＩ９１３＋１６）做了数值的长期效应的计算。 关键词：     

引力波与广义相对论

介绍了引力波的广义相对论理论基础.介绍如何通过双星周期的时间改变间接检测引力辐射,如何利用引力波的偏振效应直接检测引力波.     

Anomalous power flow and "ghost" sources

It is demonstrated that EM radiation from complex sources can result in real power in restricted regions of space flowing back towards the sources, thereby mimicking "ghost" sources. This counterintuitive mechanism of radiation does not rely on backward waves, as ordinary waves carry the power. Ways to harness the effect by making it directional are presented, together with selected applications, of which deception is a prime example due to the nature of the phenomenon. The concept can be applied to other areas, such as mechanics, acoustics, etc., and can be realized with available technology.     

Acoustic waves in structure "piezoelectric plate-polymeric nanocomposite film"

Paper is devoted to the investigation of SH(0) acoustic waves propagating in structure "piezoelectric plate-polymeric nanocomposite film". The analysis was carried out by the example of the polymeric nanocomposite film based on high-pressure polyethylene with various contents of CdS nanoparticles and lithium tantalate and lithium niobate plate. The resonant attenuation of investigated waves for the certain ratios of plate and film thicknesses was found. The obtained results open the prospects of the development of structures for SH(0) waves consisting of nanocomposite polymeric substrates and thin piezoelectric plates. Such structures may be useful for development of various thermostable chemical and biological sensors and signal processing devices.     

Direct observation of a "devil's staircase" in wave-particle interaction

We report the experimental observation of a "devil's staircase" in a time-dependent system considered as a paradigm for the transition to large-scale chaos in the universality class of Hamiltonian systems. A test electron beam is used to observe its non-self-consistent interaction with externally excited wave(s) in a traveling wave tube (TWT). A trochoidal energy analyzer records the beam energy distribution at the output of the interaction line. An arbitrary waveform generator is used to launch a prescribed spectrum of waves along the slow wave structure (a 4 m long helix) of the TWT. The resonant velocity domain associated to a single wave is observed, as well as the transition to large-scale chaos when the resonant domains of two waves and their secondary resonances overlap. This transition exhibits a "devil's staircase" behavior for increasing excitation amplitude, due to the nonlinear forcing by the second wave on the pendulum-like motion of a charged particle in one electrostatic wave.     

"Lagrange functions": a family of powerful basis sets for real-space order-N electronic structure calculations

Plane waves have unparalleled simplicity and systematic convergence by a single monotonic parameter, the energy cutoff, but they are limited to speriodic systems and require Fourier transforms that scale as N(2)logN, where N is the number of atoms. Real-space methods for order-N scaling are computationally complex and convergence depends on several variables. Here we introduce and demonstrate "Lagrange functions" as a family of analytical, complete, and orthonormal basis sets that are suitable for efficient, accurate, real-space, order-N electronic structure calculations. Convergence is controlled by a single monotonic parameter, the dimension of the basis set, and computational complexity is lower than that of plane waves.     

Approximate expressions for viscous attenuation in marine sediments: relating Biot's "critical" and "peak" frequencies

Simple approximate relations are proposed for the viscous attenuation per cycle of the fast compressional and shear waves in the low-to-intermediate frequency range. Corresponding closed-form formulas are derived for frequencies at which maximum viscous attenuation per cycle occurs according to the Biot-Stoll theory of elastic wave propagation in marine sediments. In the new formulas, Biot's approximation [M. A. Biot, J. Acoust. Soc. Am. 34, 1254-1264 (1962)] for the frequency-dependent viscosity correction factor F(f) and the assumption of relatively low specific loss (Q(-1)<(0.2) [J. Geertsma and D. C. Smith, Geophysics 26(2), 169-181 (1962)] are used to provide an accurate representation of the fast compressional and shear wave attenuation from low frequencies through a transition region extending to two or three times Biot's critical frequency f(c). The approximate viscodynamic behavior of marine sediments for the fast compressional and shear waves shows similarities to that of a "homogeneous relaxation" process for an anelastic linear element [A. M. Freudenthal and H. Geiringer, Encyclopedia of Physics (Springer-Verlag. 1958), Vol. 6].     

Oscillations and Waves in a Nonlinear System with the 1/<Emphasis Type="Italic">f</Emphasis> Spectrum

Numerical methods are used to study a spatially distributed system of two nonlinear stochastic equations that simulate interacting phase transitions. Conditions for self-oscillations and waves are determined. The 1/f and 1/k spectra of extreme fluctuations are formed when waves emerge and move under the action of white noise. The distribution of the extreme fluctuations corresponds to the maximum entropy, which is proven by the stability of the 1/f and 1/k spectra. The formation and motion of waves under external periodic perturbation are accompanied by spatiotemporal chaotic resonance in which the domain of periodic pulsations is extended under the action of white noise.     

外表面应力自由的充液有限壁厚井孔中的声场及其频散曲线的“平台”特征

为了开发一种新型标准刻度井,对外表面应力自由的充液有限壁厚井孔中的声场进行了更加深入的研究,计算分析了这种圆柱形封闭声波导结构中的声场和多阶对称模式波的频散特性。结果表明:充液有限壁厚井孔中高阶对称模式波的相速度频散曲线在一定频率范围内出现“平台”现象;当声源激发主频大于5 kHz且慢度时间相关法(STC)的窗长取4到5个周期时,得到全波波形中的“首波”速度与高阶模式波相速度频散曲线上的“平台”区域速度接近,该“平台”区域的速度与有限壁厚管材的纵波速度相差百分比随管材泊松比增加呈指数型上升;通过选择合适的管材材料以及改变其几何尺寸,可在一定频率范围内控制对称模式波相速度频散曲线的“平台”宽度、位置及平稳度。这一研究可为建立行业标准的声速刻度井提供新思路。      

Comment on "Rigorous solution for transient propagation of electromagnetic waves through a medium: causality plus diffraction in time"

In a previous Letter [Opt. Lett. 25, 995 (2000)], Xiao claimed to have found a "rigorous solution for transient propagation of electromagnetic waves through a medium." We show that Xiao's results apply strictly only to vacuum, which serves as a reference medium in classical electromagnetics.     

A spinor equation of the pure electromagnetic field. II

Spinor equations, previously found valid and interesting in dealing with plane waves of light, are applied to spherical waves. It is found that the spinors pertaining to light do not form outgoing spherical waves, as the vectors do, but they can form standing spherical waves, which the vectors usually cannot. The spinors disclose details (hidden variables) which are hidden from the accepted theories of the subatomic scale.