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In this paper, we discuss tail asymptoticsproperties for a class of infinite phase type distributions based onprobability generating function or Laplace-Stieltjes transform. The results show that, unlike finite phase cases, the tail asymptotics for the infinite phase type distributions we considered do not decaygeometrically or exponentially.     

The effect of hydrogen on the recombination of Frenkel pair in tungsten: A theoretical insight

<正>Tungsten (W), with its primary advantages, is considered as the most promising candidate for plasma facing materials (PFMs) for the next generation of fusion devices such as ITER. However, continuous bombardment with 14.1 MeV neutron introduces Frenkel defects as the primary damage in W [1]. The Frenkel defects, composed of self-interstitial atoms (SIAs) and vacancies, can develop to extended defects such as voids and interstitial clusters, resulting in hardening, swelling and embrittlement of W, thus degrading the properties of W [2]. The recombination of SIAs and vacancies is an effective way to reduce the Frenkel defects in bulk W, which enhances the radiation resistance of W based on recent theoretical calculations [3,4]. The moving of the SIA to the vacancy could finish the recombination process through instantaneous or thermally activated way [3]. The instantaneous recombination region is an ellipse with the semi-minor axis of 5.4 ? and semi-major axis of 18 ? according to the molecular dynamics calculation [4].     

Sodium dodecyl sulfate sensitized electrochemical method for subnanomole level determination of ortho-phenylphenol at a novel disposable electrode

The electrochemical behavior of ortho-phenylphenol(OPP) at a disposable electrode(an improved wax-impregnated graphite electrode) in the presence of sodium dodecyl sulfate(SDS) was studied for the first time.The results demonstrated that the electrocatalytic oxidation process of OPP was accompanied with two-charge-two-proton transference.The electronic transmission coefficient(α) and diffusion coefficient(DR) for OPP were calculated to be 0.8126 and 3.61 × 10-2 cm2/s,respectively.The electrochemical signal ...     

Simplification and normalization of indexed differentials involving coordinate transformation

In nD differential geometry, basic geometric structures and properties are described locally by differentiable functions and equations with indices that obey Einstein summation convention. Although symbolic manipulation of such indexed functions is one of the oldest research topics in computer algebra, so far there exists no normal form reduction algorithm to judge whether two indexed polynomials involving indices of different coordinate systems are equal or not. It is a challenging task in computer algebra...     

Observation of the novel “three-pointed star” cage-like (H2O)5 cluster in a polymeric solid {[Ag2(bpp)2(H2O)2](chd)·9H2O} n

Coordination polymeric solid, {[Ag₂(bpp)₂(H₂O)₂](chd)·9H₂O} _n (1) (bpp = 1,3-bis(4-pyridyl) propane, H₂chd = 1,4-cyclo-hexanedicarboxylic acid), has been obtained by the solution phase ultrasonic synthesis techniques. The structure established through X-ray structural analysis shows that the compound traps an interesting 1D water tape built by the alternating ??three-pointed star?? cage-like pentameric and D _2h tetrameric clusters (C2/c, Z = 4; a = 30.37(2) ?, b = 9.271(5) ?, and c = 18.89(1) ?; ?? = 128.47°; V = 4164(4) ?³). The novelty of the present complex is the rarely crystallographic example of the cage-shaped water pentamer, which is usually ascribed to a less-stable species. A first-principle density functional theory (DFT) calculation demonstrates that the interconnectivity between cage-like pentamers and D _2h tetramers is beneficial for contribution to the structural stabilization of these less-stable water cluster species.     

Mixed symmetry states and isospin excitation in <Emphasis Type="Italic">N</Emphasis> = <Emphasis Type="Italic">Z</Emphasis> nucleus <Superscript>52</Superscript>Fe

The interacting boson model with isospin (IBM-3) was applied to study the band structure and electromagnetic transition properties of the low-lying states in the even-even N = Z nucleus ⁵²Fe. The isospin excitation states with T = 0, 1 and 2 were identified, and compared with the available data. The study shows that the 2₃⁺ state is the lowest mixed symmetry state in ⁵²Fe. The excitation energy of the second 0₂⁺ state with T = 0 in nucleus ⁵²Fe was identified. The model calculations with the data show a reasonably good agreement. Supported by the National Natural Science Foundation of China (Grant Nos. 10765001 and 10547003), the Natural Science Foundation of Inner Mongolian Autonomous Region of China (Grant No. 200607010111), and the Scientific Research Fund of Inner Mongolian Education Bureau (Grant Nos. NJZY07155 and NJZY07153)     

A study on the sharp knee and fine structures of cosmic ray spectra

The paper investigates the overall and detailed features of cosmic ray(CR) spectra in the knee region using the scenario of nuclei-photon interactions around the acceleration sources.Young supernova remnants can be the physical realities of such kind of CR acceleration sites.The results show that the model can well explain the following problems simultaneously with one set of source parameters:the knee of CR spectra and the sharpness of the knee,the detailed irregular structures of CR spectra,the so-calledc...     

应用似然函数比以及Fourier变换计算置信度的解析方法

新粒子寻找的实验结果要通过计算置信度来解释,置信度的定义或是基于新粒子与本底并存的假设,或是基于唯有本底存在的假设.通常的计算方法是产生大量的toy Monte Carlo实验,这些实验按照某种定义的估计值的大小以顺序排列,然后将真正观测到的实验的估计值与之相比较,从而得到置信度.本文则介绍一种新的计算方法,通过定义似然函数比为实验的估计值,并应用Fourier变换,用解析的方法计算出置信度,与toy Monte Carlo方法相比,解析方法可极大地提高计算的速度和精度.     

Stability and diffusion properties of self-interstitial atoms in tungsten:a first-principles investigation

Employing a first-principles method based on the density function theory,we systematically investigate the structures,stability and diffusion of self-interstitial atoms(SIAs) in tungsten(W).The <111> dumbbell is shown to be the most stable SIA defect configuration with the formation energy of ~9.43 eV.The on-site rotation modes can be described by a quite soft floating mechanism and a down-hill "drift" diffusion process from <110> dumbbell to <111> dumbbell and from <001> dumbbell to <110> dumbbell,respectively.Among different SIA configurations jumping to near neighboring site,the <111> dumbbell is more preferable to migrate directly to first-nearest-neighboring site with a much lower energy barrier of 0.004 eV.These results provide a useful reference for W as a candidate plasma facing material in fusion Tokamak.