An experiment for the study of the Gouy effect for the squeezed vacuum

An experiment is proposed for the study of the Gouy effect associated with the wave function for the squeezed vacuum state of light. The proposed experiment relies on the connection between the phase of the wave function and the phase of an appropriately defined field amplitude.     

LAMOST光纤定位单元定位精度检测技术研究

对 L AMOST光纤定位系统光纤定位单元提出了单元定位精度非接触检测的装置。检测装置采用面阵CCD传感器 ,通过检测光纤端部出射光斑的特征点以表征定位单元上光纤端部位置。检测算法采用灰度加权平均法 ,可以达到亚像素级的检测精度。介绍了提高检测精度的主要措施 ,装置选用白光照明 ,对所采集的图像采用多次平均的方法 ,提高了装置的稳定性。     

Method for calculating the complete expansion of the Glauber amplitude for nucleus-nucleus scattering

A method for calculating the complete expansion of the Glauber amplitude for nucleus-nucleus scattering processes is proposed. An example of the calculation of the elastic differential cross section is given as an illustration.     

New method for the evaluation of the RKR potential-integrals for diatomic molecules

We present a new method for the evaluation of the RKR potential-integrals for diatomic molecules. This method is straightforward and fast, and the calculations can be performed to an accuracy better than any other method.     

Mapping of the roughness exponent for the fuse model for fracture

The roughness exponent for fracture surfaces in the fuse model has been thought to be universal for narrow threshold distributions and has been important in the numerical studies of fracture roughness. We show that the fuse model gives a disorder dependent roughness exponent for narrow disorders when the lattice is influencing the fracture growth. When the influence of the lattice disappears, the local roughness exponent approaches zeta(local)=0.65+/-0.03 for distribution with a tail toward small thresholds, but with large jumps in the profiles giving corrections to scaling on small scales. For very broad disorders the distribution of jumps becomes a Lévy distribution and the Lévy characteristics contribute to the local roughness exponent.     

Correcting the concept of denseness for the bootstrap

One way of stating the bootstrap theory is to say that hadrons are ‘dense’. In order for this to have a truly physical meaning, and in order for the abstract idea of infinite cardinality to be rigorously self-consistent, it is necessary to redefine the concept of denseness to mean that size is increasing as velocity.     

Method for the selection of sentence materials for efficient measurement of the speech reception threshold

A method is described to select sentence materials for efficient measurement of the speech reception threshold (SRT). The first part of the paper addresses the creation of the sentence materials, the recording procedure, and a listening experiment to evaluate the new speech materials. The result is a set of 1272 sentences, where every sentence has been uttered by two male and two female speakers. In the second part of the paper, a method is described to select subsets with properties that are desired for an efficient measurement of the SRT. For two speakers, this method has been applied to obtain two subsets for measurement of the SRT in stationary noise with the long-term average spectrum of speech. Lastly, a listening experiment has been conducted where the two subsets (each comprising 39 lists of 13 sentences each) are directly compared to the existing sets of Plomp and Mimpen [Audiology 18, 43-52 (1979)] and Smoorenburg [J. Acoust. Soc. Am. 91, 421-437 (1992)]. One of the outcomes is that the newly developed sets can be considered as equivalent to these existing sets.     

Calibration of the X-Ray spectroheliograph Mg XII for the 0.84 nm spectral line for the TESIS experiment

The spectroheliograph for monochromatic imaging of the solar corona at the 0.84 nm resonance line of a Mg XII ion is a part of the TESIS instrumentation onboard the CORONAS-PHOTON satellite. The main optical elements of the spectroheliograph are the focusing crystalline mirror and imaging detector based on a CCD array. The optical scheme of the spectroheliograph, procedure, and results of calibrations of the optical elements within the working spectral range are presented. Diffraction efficiency and the rocking curve of the crystalline mirror, sensitivity, and radiation hardness of the detector were measured. It was found that the diffraction efficiency is 10%, the width of the rocking curve is ～3′, the detector sensitivity is 31 ADC units per photon, and the radiation hardness is better than 10⁷ rad within the working spectral range.     

On the problems of the application of atomic-force microscopes for studying the surface roughness of elements for imaging optics

The key problems of applying atomic-force microscopes when studying the surface roughness of elements for imaging optics are discussed. Special attention is paid to optics of ultrahigh spatial resolution with an operating wavelength of no shorter than 100 nm. It is proposed that a specialized microscope for optical applications equipped with a tetraaxial goniometer be developed.     

利用超格子模型对布拉格光纤的研究

为了研究布拉格光纤的模式特征和传输特性,提出了超格子模型,利用傅里叶级数表示光纤横向折射率分布,利用平面波展开法分析布拉格光纤的能带结构,基于厄米-主斯函数的局域正交函数展开法,从全矢量耦合波动方程出发,得到关于模式传播常量和电场展开系数的本征方程,从而分析布拉格光纤的模式特征。以高折射率芯布拉格光纤为例,实现了该算法,得到基模与二次模的横向电场分布、基模色散曲线和模式双折射。基模的模式双折射可用于衡量算法的精度,结果表明该算法精度较高。超格子模型不仅可以用于研究高折射率芯布拉格光纤,而且同样可以研究低折射率区域导光的布拉格光纤。     

Mechanisms for the SAR Imaging of the Ocean

We perform a comparative analysis of two mechanisms for the formation of a synthetic aperture radar (SAR) image of the ocean, which are related to orbital velocities on the surface. It is shown that the mechanism of fluctuations of the effective density of scatterers, which is commonly accepted at present as the physical basis for the SAR diagnostics of roughness, actually works only in the case of a sufficiently flat swell. In the presence of wind roughness, the dominant role is played by another mechanism, namely, fluctuations of the number of surface elements whose images are randomly shifted and superimposed in the image plane due to orbital velocities. In the case of a developed wind roughness propagated in the azimuthal direction, the power contributions of two above-mentioned mechanisms to the SAR imaging of the ocean differ by about two orders of magnitude.     

Recommendations for enhancing the role of the auditory modality for processing sonar data

Submarine warfare continues to pose a threat in present-day military operations. Visual displays play a dominant role for operator detection and classification of underwater and surface targets. However, the visual modality is ineffective for the detection of transient signals. In spite of quieter submarines, transient sounds such as hull popping are difficult to disguise, which makes them more likely to be detected via an auditory display. Operators tend to use auditory displays less often because several factors can impede effective aural processing. In this paper, the sonar problem is reviewed followed by some proposed techniques for making more effective use of the auditory modality for the presentation of sonar signals as a means of further improving operator detection and classification of targets. Some recommendations for augmenting the aural presentation of sonar signals over headphones are then discussed. Key research areas include: (1) a reduction of the sound level of the ambient noise in noisy environments should improve the likelihood that the operator will detect weak signals; (2) the provision to replay sound bites of interest and to compare these against a library of known archetypes should lead to increased accuracy in target classification; (3) the ability to present sonar beams in a three-dimensional auditory display where the spatial position of each sonar beam corresponds to the actual position of the source in the ocean should enable the operator to monitor multiple beams and increase his/her situational awareness. Ultimately, the viability of an auditory display is dependent on operator hearing acuity.     

Hydrodynamic symmetries for the Whitham equations for the sine-Gordon equation

The effective structure of the hydrodynamic symmetries for the Whitham equations, derived for simplest one-phase solutions of the sine-Gordon equation, is presented. This structure is analogous to the one, that was obtained for the Whitham equations for the KdV equation and the nonlinear Schrödinger equation (NSE). The hydrodynamic symmetries for the gas dynamic equations are described.     

On the continuity of the boosts for each orbit

The possibility of a continuous choice of the boost for each orbit is studied by making use of some mathematical theorems on fibre bundles and it is shown that this choice is possible only for massive particles.     

On the choice of the test structure for the electrical characterization of dielectrics for silicon solar cells

Surface passivation of Si solar cells is typically achieved by deposition of a dielectric layer. Via the investigation of Al₂O₃ passivation layers, we show that care must be taken when performing capacitance–voltage (C –V) measurements in order to obtain results that are meaningful at solar cell level. The passivation properties of a dielectric are not only affected by post‐deposition treatments but also by the presence and the nature of a metal covering the dielectric. Consequently, this Letter emphasizes how important it is to perform C –V measurements on a device structure that resembles as closely as possible that of the finished solar cell, using the same metal, deposition technique and thermal budget. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solution of the Percus-Yevick equation for the Widom-Rowlinson model

The Percus-Yevick equation for the Widom-Rowlinson model is solved exactly in one and three dimensions. In one dimension the direct correlation function is obtained explicitely. In three dimensions only the thermodynamic properties have been obtained so far implicitely in terms of elliptic integrals, and there is a maximum density beyond which the P.Y. equation has no solution and that before that density is ‘critical density’ at which the homogenous state becomes unstable.     

Representation of the spin in the Dirac equation for the electron

The conventional interpretation of the spin matrices contained in the Dirac equation for the electron is considered to be mostly unintelligible in the operational sense. It is shown that it appears that the interpretation is often illogical. The necessity of a more comprehensible interpretation of the concerned equation is implied.     

Calculation of the Green function for the Laplace equation

A modification of the traditional method of calculating the Green function in a layered medium is suggested that allows one to substantially increase its accuracy. In addition, a technique for calculating the Green function that makes it possible to control the accuracy of the calculated potential is offered. This technique is based on the properties of the Bessel and Struve functions. An example of calculation using the suggested technique is illustrated. The results may be extended for a wide class of problems the solution to which requires calculation of the Green function for the Laplace equation in a layered medium.     

Construction of the Jordan basis for the Baker map

The Jordan canonical form basis states for an invertible chaotic map, the Baker map, are constructed. A straightforwardly obtained recursion formula is presented for construction of the Jordan states and of the spectral decomposition of the Frobenius-Perron evolution operator. Comparison of this method with earlier, subdynamics techniques demonstrates that it is much more direct and simpler. The physical significance of the Jordan states is approached from the point of view of an entropy evolution equation. The method is also applied to the Bernoulli map, yielding its eigenstates more straightforwardly than done previously. (c) 1997 American Institute of Physics.     

Optics for the lattice of the compact storage ring for a Compton X-ray source

We present two types of optics for the lattice of a compact storage ring for a Compton X-ray source. The optics design for different operation modes of the storage ring are discussed in detail. For the pulse mode optics, an IBS-suppression scheme is applied to optimize the optics for lower IBS emittance growth rate; as for the steady mode, the method to control momentum compact factor is adopted [Gladkikh P, Phys. Rev. ST Accel. Beams 8, 050702] to obtain stability of the electron beam.