57Fe Mössbauer study of amorphous and nanocrystalline Fe73.5Nb3Cu1Si13.5B9 after neutron irradiation

⁵⁷Fe Mössbauer spectroscopy is used to study neutron irradiation induced changes in the short-range order of Fe_73.5Nb₃Cu₁Si_13.5B₉ alloy. The samples are investigated in both amorphous and nanocrystalline states. Neutron irradiation leads to an increase of the standard deviation of a hyperfine field distribution (HFD), implying rearrangement of the atoms towards disordering. Simultaneously, changes in the average value of the hyperfine field and a net magnetic moment position occur as a consequence of a spin reorientation, atom mixing and microscopic stress centres which are introduced by neutron irradiation.     

Quantum HeisenbergS=1/2 spin glass with ferromagnetic coupling and random Dzyaloshinskii-Moriya interactions

By means of the generalized static replica symmetric spin glass theory, a quantum HeisenbergS=1/2 spin glass model with the infinite-ranged random Dzyaloshinskii-Moriya (DM) interaction and ferromagnetic coupling is investigated. The dependence of entropy, specific heat, susceptibility and the corresponding order parameters on temperature is studied numerically for different ferromagnetic interactions and fixed anisotropy. Two spin glass phases has been found including transverse and mixed spin glass phases. It has been shown that the local susceptibility exhibits double-cusp features for different ferromagnetic coupling (J ₀). Phase transition poins are found in the specific heat-temperature plane at various ferromagnetic coupling values. Additionally, the dependence of the spontaneous moment on temperature is calculated.     

高Jc Tl系2223相银包套带材的磁通钉扎和耗散

测量了Ｔｌ系２２２３相银包套超导带（Ｊ_c＝１．５×１０^４Ａ·ｃｍ^-2，７７Ｋ，０Ｔ）在０－０．８Ｔ磁场下电阻转变展宽，实验结果引用热激活磁通蠕动模型加以解释。磁场平行于带面（Ｈ∥ａｂ面）和磁场垂直于带面（Ｈ⊥ａｂ面）两种情况下，激活能与磁场之间满足幂指数关系：Ｕ_0∥＝０．２１ H^-0.3(eV),Ｕ_0⊥＝０．１5 H^-0.4(eV)，其中Ｈ的单位为ｋＧ。 关键词：     

Phase transitions on clean Si(110) surfaces

The properties of the structure of clean Si(110) surfaces have been investigated by LEED. The phase transitions between surface structures Si(110)?(4 × 5), Si(110)?(2 × 1) and Si(110)(5 × 1) take place at about 600 and 750°C. The time of reconstruction from the high temperature phase to the low temperature phase may exceed the time of the sample cooling. That explains why the Si(110)?(2 × 1) and the Si(110)?(5 × 1) superstructures may be seen at room temperature. Surface defects favour the retaining of high temperature phases on the surface at room temperature. The transition from the Si(110)?(5 × 1) structure to the Si(110)?(2× 1) structure and conversely in the temperature range of 720–750°C apparently occurs through formation of the intermediate structures Si(110)?(7 × 1) and Si(110)?(9 × 1). The models are given of superstructures observed by LEED.     

The temperature dependence of some thermodynamical quantities of ferromagnetic alloys in the region of magnetic phase transition

This paper deals with the behaviour of ferromagnetic alloys in the region of magnetic phase transition. The temperature dependences of spontaneous magnetization, magnetic susceptibility and specific heat are discused. The theoretical results are compared with experimental data.I wish to thank Professor L.Valenta for his kind guidance and advice given to me during my work on this paper.     

Absorption spectrum of CO2 in the 4.82-μm region

The absorption spectrum of CO₂ in the 4.82-μm region has been observed with a high-resolution spectrometer. The (11¹0, 03¹0)_I-00⁰0 transition and the “hot” transitions (12²0, 04²0)_I-01¹0 and (20⁰0, 04⁰0)_I-01¹0 have been calibrated. The effective rotational constants of the upper levels have been deduced with good accuracy.     

Arrangements on Parametric Surfaces II: Concretizations and Applications

We describe the algorithms and implementation details involved in the concretizations of a generic framework that enables exact construction, maintenance, and manipulation of arrangements embedded on certain two-dimensional orientable parametric surfaces in three-dimensional space. The fundamentals of the framework are described in a companion paper. Our work covers arrangements embedded on elliptic quadrics and cyclides induced by intersections with other algebraic surfaces, and a specialized case of arrangements induced by arcs of great circles embedded on the sphere. We also demonstrate how such arrangements can be used to accomplish various geometric tasks efficiently, such as computing the Minkowski sums of polytopes, the envelope of surfaces, and Voronoi diagrams embedded on parametric surfaces. We do not assume general position. Namely, we handle degenerate input, and produce exact results in all cases. Our implementation is realized using Cgal and, in particular, the package that provides the underlying framework. We have conducted experiments on various data sets, and documented the practical efficiency of our approach.     

On the Solutions of the Generalized Reaction-Diffusion Model for Bacterial Colony

In this paper, the Adomian’s decomposition method has been developed to yield approximate solution of the reaction-diffusion model of fractional order which describe the evolution of the bacterium Bacillus subtilis, which grows on the surface of thin agar plates. The fractional derivatives are described in the Caputo sense. The method introduces a promising tool for solving many linear and nonlinear fractional differential equations. In these schemes, the solution takes the form of a convergent series with easily computable components. Numerical results show that the approach is easy to implement and accurate when applied to partial differential equations of fractional order.     

A modified functional delta method and its application to the estimation of risk functionals

The classical functional delta method (FDM) provides a convenient tool for deriving the asymptotic distribution of statistical functionals from the weak convergence of the respective empirical processes. However, for many interesting functionals depending on the tails of the underlying distribution this FDM cannot be applied since the method typically relies on Hadamard differentiability w.r.t. the uniform sup-norm. In this article, we present a version of the FDM which is suitable also for nonuniform sup-norms, with the outcome that the range of application of the FDM enlarges essentially. On one hand, our FDM, which we shall call the modified FDM, works for functionals that are “differentiable” in a weaker sense than Hadamard differentiability. On the other hand, it requires weak convergence of the empirical process w.r.t. a nonuniform sup-norm. The latter is not problematic since there exist strong respective results on weighted empirical processes obtained by Shorack and Wellner (1986) [25], Shao and Yu (1996) [23], Wu (2008) [32], and others. We illustrate the gain of the modified FDM by deriving the asymptotic distribution of plug-in estimates of popular risk measures that cannot be treated with the classical FDM.     

Normal solvability of boundary value problems for a class of fourth-order operator-differential equations in a weighted space

In a weighted space, we find sufficient conditions for the normal solvability of a boundary value problem for a class of fourth-order operator-differential equations whose leading part has multiple characteristics. Note that these conditions are expressed in terms of properties of operator coefficients of the equation considered.