Investigation of the properties of the flux and interaction of ultrahigh-energy cosmic rays by the method of local-muon-density spectra

A new method for studying extensive air showers is considered. The method is based on the phenomenology of the localmuon density. It is shown that measurement ofmuon-density spectra at various zenith angles makes it possible to obtain information about the energy spectrum, mass composition, and interaction of cosmic rays over a broad range of energies (10¹⁵–10¹⁸ eV) by using a single array of comparatively small size. The results obtained from a comparison of experimental data on muon bundles from the DECOR coordinate detector with the results of simulation performed under various assumptions on the properties of the primary flux and for various hadron-interaction models are presented, and possible versions of the interpretation of these results are discussed.     

Study of photons reflection on rough surface

The purpose of this paper is to study the probability distribution of photon reflection on rough surface experimentally and theoretically. We showed experimentally that for photon reflection on rough surface, the distribution was characterized by the ratio τ/σ, which was defined as the “correlation roughness” of the reflecting surface. Quantitative experimental results based on single-photon counter are compared to the Monte Carlo simulation results. At last, how the intensity of low light-level can be retrieved from photon counting results using improved models is shown.     

Heavy doping effects on donor-acceptor spectra of polar semiconductors at low temperatures

The heavy doping effects on donor-acceptor (DA)-pair spectra at small DA-pair distances R are investigated, basing on an effective screened impurity potential model given by Morgan and on the results of the R-dependent electron (hole)—longitudinal optical phonon interaction energy obtained by Kartheuser et al. It is suggested that the deviation of the electron—hole recombination energy by dense impurities (or at small R), found from the energy of the emitted photon for a zero-phonon transition, results from the band-gap narrowing effect.At large R, we have found that the energy gap of the pure ZnSe crystal is equal to 2.827 eV, in good agreement with observed results. Finally, at small R, our numerical results applied to ZnSe doped with ln and Li impurities are compared with other theories and with observed results.     

Thermoreflectance spectra of the ferroelectric phase of semiconducting SbSI

Thermoreflectance measurements on SbSI between 2.2 and 3.0 eV are reported at 110°K. Strong polarization effects have been found to depend on the orientation of the electric vector with respect to the c-axis. Correlations, between present results and previously reported reflectivity and its logarithmic derivative results are presented.     

视觉估计显示器gamma在Internet网络上的应用

使用自行开发出的基于Web的gamma估计程序,分别通过Internet对CRT和LCD显示器在暗、微暗和办公环境三种观察环境下,进行了视觉估计显示器gamma精确度研究实验.实验得出：不同实验者估计偏差范围,对CRT和LCD显示器分别是0.13和0.20|估计与测量结果的平均误差范围,对CRT和LCD显示器分别是0.07和0.17|gamma估计基本与观察环境无关|观察视角对LCD显示器gamma值影响很大|显示器的“亮度”和“对比度”设置,不影响视觉估计结果.     

Vibration analysis of annular-like plates

The existence of eccentricity of the central hole for an annular plate results in a significant change in the natural frequencies and mode shapes of the structure. In this paper, the vibration analysis of annular-like plates is presented based on numerical and experimental approaches. Using the finite element analysis code Nastran, the effects of the eccentricity, hole size and boundary condition on vibration modes are investigated systematically through both global and local analyses. The results show that analyses for perfect symmetric conditions can still roughly predict the mode shapes of “recessive” modes of the plate with a slightly eccentric hole. They will, however, lead to erroneous results for “dominant” modes. In addition, the residual displacement mode shape is verified as an effective parameter for identifying damage occurring in plate-like structures. Experimental modal analysis on a clamped-free annular-like plate is performed, and the results obtained reveal good agreement with those obtained by numerical analysis. This study provides guidance on modal analysis, vibration measurement and damage detection of plate-like structures.     

Sequence of structural phase transitions of CsInF4 crystal

In this work we employ calorimetric and dielectric techniques to study the sequence of structural phase transitions (SPTs) of CsInF₄ crystal in the temperature range from 450 to 250 K. Our results show three first-order SPTs. Based on these results and on direct interferometric observation of the domain patterns, we discuss the elastic state of CsInF₄ phases.     

Photonuclear reactions on the cadmium isotopes <Superscript>106,108</Superscript>Cd at the bremsstrahlung endpoint energy of 55.5 MeV

The gamma-activation technique was used to measure the absolute yields of photonuclear reactions on the cadmium isotopes ^106,108Cd. The results obtained in this way were compared with the results of the calculations based on the statistical model. For reactions on the isotope ¹⁰⁸Cd, agreement between these theoretical and experimental results is good, but the experimental ratio of the yields of photoproton and photoneutron reactions on the isotope ¹⁰⁶Cd differs substantially from its theoretical counterpart. The results of our present study are discussed from the point of view of the production of bypassed nuclei in the p-process of nucleosynthesis.     

The attenuation of ultrasound in water-alcohol mixtures by the method of streaming

Experimental results on the attenuation of ultrasound in polar-polar liquid, that is, water-alcohol mixtures, by the method of streaming are presented. A comparative study of the results obtained by this method and those obtained by other methods has been made. Results of the present investigations agree well with those obtained by other workers. From the observed attenuation data, the bulk viscosity coefficients ‘b’ of the mixtures have been determined using Eckart's formalism on streaming.Satisfactory results could be obtained in the cases of water/methyl alcohol, and water/ethyl alcohol mixtures at all percentage compositions of mixtures but in the case of water/n-propyl alcohol satisfactory results could not be obtained at 5% to 40% mixture compositions. This observation bears the similarity with the cases of pure non-polar liquids. Here the observed results have been attempted to be explained, at least on the basis of relevant physical principles, in terms of dipole moment and dielectric constant.     

Tm3+掺杂光纤激光制冷的理论分析

近年来，掺Tm³⁺：ZBLANP玻璃已成为固体材料激光冷却领域中最有希望的新材料之一，但有关掺Tm³⁺：ZBLANP光纤的激光冷却尚未见到理论研究与实验报道.本文采用一个简单的理论模型，就Tm³⁺：ZBLANP光纤的激光冷却进行了理论研究与分析，讨论了量子效率、抽运功率、背景吸收、出射荧光波长变化和环境黑体辐射等对激光制冷效果的影响，得到了一些有趣的重要结果，可为掺Tm³⁺：ZBLANP光纤的激光冷却实验提供可靠的理论 关键词： 固体激光冷却 反斯托克斯荧光 3+：ZBLANP光纤')" href="#">掺Tm³⁺：ZBLANP光纤     

Theoretical investigation of the influence of isotope mass on chemicurrents during adsorption of H on K(110)

Using our recently developed method for calculation of electron–hole (e–h) spectra in adsorption on metal surfaces [Phys. Rev. B 19:165407, 2009], we investigate the system H/K(110). Comparing to our previous results for H/Al(111), we show that the narrower conduction band of K in contrast to Al leads to notable differences in the excitation spectra of electrons and holes. We also find that our results do not obey the scaling of the number of excited charge carriers above a certain energy barrier with the particle's velocity, which is in our case mainly depending on the isotope mass. Instead, we find a different (approximately m^1/6 rather than m^1/2) scaling. Extrapolating our results to adsorbates with large masses, we expect larger electronic excitations than from the “forced oscillator” approach. This makes the electronic dissipation channel for energy more important even for heavy adsorbates. Our results are in qualitative agreement with other theoretical and experimental results.     

CH4-O2-N2预混气体爆炸二维数值模拟

 利用CFD软件,基于ISAT算法和简化的甲烷氧化基元反应模型,建立了CH₄-O₂-N₂预混气体的二维湍流爆炸模型。数值计算结果表明,该模型较好地模拟了CH₄-O₂-N₂预混气体在高温气团作用下的点火、燃烧和爆炸过程。计算中,考察了高温点火气团的初始温度和混合气体初始组分对CH₄-O₂-N₂预混气体燃烧和爆炸过程的影响。结果表明：高温气团的初始温度对CH₄-O₂-N₂预混气体的点火延迟时间和燃烧初始阶段有重要影响,但对CJ爆燃没有影响;惰性气体N₂的加入,降低了混合气体的反应活性,导致点火延迟时间增大,燃烧反应速度、爆炸超压和重要自由基浓度都随之减小。相同条件下爆炸超压峰值的计算结果与实验测量结果符合较好。     

TiO2电子结构与其双折射性、各向异性 关联的理论研究

采用基于密度泛函理论的第一性原理平面波超软赝势方法对锐钛矿相TiO₂的晶体结构、能带结构、态密度等电子结构进行了理论分析, 在此基础上对介电函数、能量损失函数、光电导率等光学性质进行系统的理论计算, 分析了TiO₂双折射现象、各向异性与电子结构之间的关联, 其结果与文献报道的相关实验结果相符合, 从理论上探讨了TiO₂电子结构和其双折射现象、各向异性的特征.     

Nanosecond and femtosecond UV laser ablation of polymers: Influence of molecular weight

We examine the nanosecond and femtosecond UV laser ablation of poly(methyl methacrylate) (PMMA) as a function of molecular weight (M_w). For laser ablation with nanosecond laser pulses, at the excimer wavelengths 248 nm and 193 nm, we show that high temperatures develop; yet the dynamics of material ejection differs depending on polymer M_w. The results on the nanosecond ablation of polymers are accounted within the framework of bulk photothermal model and the results of molecular dynamics simulations. Turning next to the 248 nm ablation with 500 fs laser pulses, the ablation threshold and etching rates are also found to be dependent on polymer M_w. In addition, ablation results in morphological changes of the remaining substrate. Plausible mechanisms are advanced.     

Vibration of simply supported cylindrical shells with longitudinal stiffeners

The vibration of simply supported cylindrical shells stiffened by discrete longitudinal stiffeners is investigated by using an energy method. Vlasov's thin walled beam theory is used for stringers. Shell theories based on Donnell's approximate theory and Flügge's more exact theory are used for the skin and numerical results indicate that Donnell's approximate theory gives excellent results for the stiffened shells. Sinusoidal wave form is considered in the longitudinal direction, and mode shapes in the circumferential direction are represented by Fourier series. Numerical results on frequencies and mode shapes computed for a shell stiffened by various number of stiffeners are presented and compared favorably with existing experimental results and other analytical solutions.     

光场的非傍轴性对光谱移动和光谱开关的影响

利用瑞利衍射积分公式，推导出多色高斯光束被硬边光阑衍射后光谱的解析公式，傍轴近似的光谱公式可作为特例得到.着重研究了束腰宽度与中心波长之比w₀/λ₀和截断参数δ对光谱移动和光谱开关的影响.结果表明，只有当w₀/λ₀和δ满足一定条件时，傍轴近似结果才与非傍轴结果一致.光场的非傍轴性会引起光谱移动不同和产生光谱开关的临界位置变化. 关键词： 非傍轴光场 高斯光束 光谱移动 光谱开关     

Numerical Method of Determining the Cutoff Frequency and Mode Speckle Pattern of Optical Waveguides

Based on a numerical solution of the nonstationary wave equation, an algorithm for determining the eigenfunctions and eigenvalues of the LP_im modes of axially symmetric optical waveguides is suggested. The cutoff frequency of the LP₁₁ mode of different waveguides is determined using the algorithm constructed. The results obtained are compared with the well-known analytical formulas and results of numerical calculations for the equivalent step-index waveguide model. Based on the analytical results obtained, an eigenfunction and eigenvalue search algorithm is suggested for a waveguide with a two-dimensional refractive index profile (in particular, for an axially nonsymmetric waveguide).__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 11–16, January, 2005.     

不同滤波方法在去趋势波动分析中去噪的应用比较

研究了连续噪声和尖峰噪声对去趋势波动分析的影响,发现噪声的存在使得双对数曲线在尺度较小时发生了"转折"现象.针对这一问题,文中采用三种不同滤波方法对理想时间序列进行了实验,结果表明,多级Vondrak滤波得到的高频序列与真实噪声序列无论是在强度还是在演变趋势上都展现出惊人的一致性,低频滤波序列的去趋势波动分析结果与真实信号十分接近,多级Vondrak滤波基本上能够消除由于噪声所引起的"转折"现象,而且这一研究结果对于滤波周期阈值的依赖性并不太大.多点滑动加权平均滤波虽然能够在一定程度上减轻噪声对于去趋势波动的影响,但不能从根本上消除由于噪声所引起的"转折"现象.快速傅里叶滤波在选择合适的滤波周期阈值时,能够基本消除噪声对去趋势波动分析的影响,但是由于其滤波结果对于滤波周期阈值的依赖较大,在实际应用中滤波周期阈值的选取比较困难.因此,多级Vondrak滤波是消除噪声对去趋势波动分析结果影响的一种有效的途径. 关键词： 多级Vondrak滤波 去趋势波动分析 多点滑动加权平均滤波 快速傅里叶滤波     

Comparison of microscopic calculations of solid neutron star matter

At the Urbana Workshop on “dense neutron matter” it was agreed that each group involved should check the many-body techniques so far employed on a test problem, outlined by H. A. Bethe. This paper reports the results using the t-matrix and variational approaches. Satisfactory agreement is obtained. Comparison with the results of other groups is discussed.