Are gamma-ray bursts the sources of ultra-high energy cosmic rays?

We reconsider the possibility that gamma-ray bursts (GRBs) are the sources of the ultra-high energy cosmic rays (UHECRs) within the internal shock model, assuming a pure proton composition of the UHECRs. For the first time, we combine the information from gamma-rays, cosmic rays, prompt neutrinos, and cosmogenic neutrinos quantitatively in a joint cosmic ray production and propagation model, and we show that the information on the cosmic energy budget can be obtained as a consequence. In addition to the neutron model, we consider alternative scenarios for the cosmic ray escape from the GRBs, i.e., that cosmic rays can leak from the sources. We find that the dip model, which describes the ankle in UHECR observations by the pair production dip, is strongly disfavored in combination with the internal shock model because (a) unrealistically high baryonic loadings (energy in protons versus energy in electrons/gamma-rays) are needed for the individual GRBs and (b) the prompt neutrino flux easily overshoots the corresponding neutrino bound. On the other hand, GRBs may account for the UHECRs in the ankle transition model if cosmic rays leak out from the source at the highest energies. In that case, we demonstrate that future neutrino observations can efficiently test most of the parameter space – unless the baryonic loading is much larger than previously anticipated.     

Primordial black holes from monopoles connected by strings

Primordial black holes (PBHs) are known to be produced from collapsing cosmic defects such as domain walls and strings. In this paper we show how PBHs are produced in monopole-string networks.     

Cosmological models with the variable gravitational and cosmological constants

Cosmology with the gravitational and cosmological constants generalized as coupling scalars in Einsteins theory is considered. A general method of solving the field equations is given. Exact solution for Zeldovich fluid satisfying G=G ₀(R/R ₀) ⁿ is given.     

Nonlinear spinor field in Bianchi type-I Universe filled with viscous fluid: numerical solutions

We consider a system of nonlinear spinor and a Bianchi type I gravitational fields in presence of viscous fluid. The nonlinear term in the spinor field Lagrangian is chosen to be λ F, with λ being a self-coupling constant and F being a function of the invariants I an J constructed from bilinear spinor forms S and P. Self-consistent solutions to the spinor and BI gravitational field equations are obtained in terms of τ, where τ is the volume scale of BI universe. System of equations for τ and ε, where ε is the energy of the viscous fluid, is deduced. This system is solved numerically for some special cases.      

Point defects in crystalline zircon (zirconium silicate), ZrSiO<Subscript>4</Subscript>: electron paramagnetic resonance studies

This article outlines the present state of knowledge of paramagnetic defects in crystalline zircon as obtained mainly, but not exclusively, from electron paramagnetic resonance (EPR) studies in crystalline zircon (zirconium silicate, ZrSiO₄). The emphasis is on single-crystal studies where, in principle, unambiguous analysis is possible. Firstly, the crystallography of zircon is presented. Secondly, the relationships between available crystal-site symmetries and the symmetries of observed paramagnetic species in zircon, and how these observations lead to unambiguous assignments of point-group symmetries for particular paramagnetic species are detailed. Next, spin-Hamiltonian (SH) analysis is discussed with emphasis on the symmetry relationships that necessarily exist amongst the Laue classes of the crystal sites in zircon, the paramagnetic species occupying those sites and the SH itself. The final sections of the article then survey the results of EPR studies on zircon over the period 1960–2002.     

Features of coated diamonds from the Snap Lake/King Lake kimberlite dyke, Slave craton, Canada, as revealed by optical topography

Confocal photoluminescence (PL) and local absorption spectroscopy were used to study the types and spatial distribution of point defects in coated diamonds, the input of which is about 30% in the Snap Lake deposit, Canada. Nitrogen concentration is on the level of several hundreds of ppm in the core, with a nitrogen-poor layer in its outer part, whereas in the coat it is usually several times higher as a result of fast growth. Nitrogen defects in the core are strongly aggregated with N3, B and B′-forms dominating, whereas A-defects are typical of the coat. The rounded shape of the coated diamonds is a result of the combined effect of partial dissolution of the octahedral core and the “abnormal” growth of the coat, which produces a fibrous structure. Analysis of PL and PL excitation spectra showed that structureless yellow-green PL of the coat is likely to be due to nickel-nitrogen complexes with their fine structure broadened in the strain fields. The presence of irradiation/annealing products such as vacancies V⁰ and nitrogen-vacancy complexes NV⁻, N₂V₂ shows that the diamonds studied have undergone post-growth ionizing irradiation with further low-temperature annealing in natural conditions.     

裘布依公式在实际应用中的缺陷分析

主要通过对裘布依公式中：1）实际流量（Q）-降深（s）曲线与理论的差异,2）实际井径对流量的影响与理论的差异,3）井中最大流量,4）影响半径等问题的分析,指出裘布依公式的缺陷,并分别提出了一定的解决方案。同时还结合土力学的相关知识,从“达西定律的适用范围”,“渗透系数的不唯一性”,“地基沉降导致含水层变形”三个方面分析了公式的不足之处,更全面地对问题进行了剖析。     

含有腐蚀缺陷海底管道极限载荷分析

利用有限元弹塑性分析方法,对含有腐蚀缺陷的海底管道进行材料非线性和几何非线性分析,探讨了确定管道极限载荷的准则。在此基础上,给出含有腐蚀缺陷的海底管道的极限载荷,研究腐蚀长度、深度和宽度对海底管道极限载荷的影响,提出了含有腐蚀缺陷的受内压的海底管道的极限载荷计算公式,并与试验结果进行了比较,证明该方法是有效的。     

内置空心钢球的圆截面钢管混凝土柱抗震性能试验

为研究带空心钢球的钢管混凝土柱的抗震性能,以空心率和含钢率为参数,设计制作9个内置空心钢球的圆截面钢管混凝土柱和3个薄壁圆截面钢管混凝土柱,并进行拟静力试验,结合破坏形态通过延性系数和累积耗能等参数探讨了试件的抗震性能。研究结果表明:含钢率对内置空心钢球的薄壁圆形钢管混凝土柱极限荷载,峰前耗能的影响较大,空心率对试件延性系数,峰后耗能的影响显著;内置空心钢球的薄壁圆形钢管混凝土柱较实心薄壁圆形钢管混凝土柱极限荷载有所降低;试件水平荷载时程曲线的"V"字形波动的折线可以较直观的反映出结构损伤破坏过程,并在曲线数形与试验现象关联上和滞回曲线形成较好的一致性;可以通过优化内置空心钢球的大小和壁厚设计钢管混凝土柱,并取得与实心钢管混凝土柱同样的抗震性能,为同类钢管混凝土组合结构的设计提供了依据。     

软土地区基坑开挖引起桩基质量问题的判定与处理

软土地区在基坑开挖时常常引起桩基破坏等工程问题,特别是在沿海、沿江等软土地区发生较多。以江苏一个沿江电厂为工程实例,通过对桩基位移和桩身裂缝的数据统计分析,揭示了基坑开挖时桩基发生移位、倾斜甚至断桩的真实原因。通过桩基取心试验、超声波试验和开挖验证找到了产生桩身缺陷的原因。此外还结合工程实例,提出了桩基出现质量问题时,可采取补强注浆的方法进行补救和处理,实践证明提出的处理方法效果良好。