Group connectivity in line graphs

Tutte introduced the theory of nowhere zero flows and showed that a plane graph G has a face k-coloring if and only if G has a nowhere zero A-flow, for any Abelian group A with |A|≥k. In 1992, Jaeger et al. [9] extended nowhere zero flows to group connectivity of graphs: given an orientation D of a graph G, if for any b:V(G)?A with ∑_v∈V(G)b(v)=0, there always exists a map f:E(G)?A−{0}, such that at each v∈V(G), in A, then G is A-connected. Let Z₃ denote the cyclic group of order 3. In [9], Jaeger et al. (1992) conjectured that every 5-edge-connected graph is Z₃-connected. In this paper, we proved the following.

• (i) 

  Every 5-edge-connected graph is Z3-connected if and only if every 5-edge-connected line graph is Z3-connected.

• (ii) 

  Every 6-edge-connected triangular line graph is Z3-connected.

• (iii) 

  Every 7-edge-connected triangular claw-free graph is Z3-connected.

In particular, every 6-edge-connected triangular line graph and every 7-edge-connected triangular claw-free graph have a nowhere zero 3-flow.     

A novel monochromator for experiments with ultrashort X‐ray pulses

Aiming at advancing storage‐ring‐based ultrafast X‐ray science, over the past few years many upgrades have been undertaken to continue improving beamline performance and photon flux at the Femtoslicing facility at BESSY II. In this article the particular design upgrade of one of the key optical components, the zone‐plate monochromator (ZPM) beamline, is reported. The beamline is devoted to optical pump/soft X‐ray probe applications with 100 fs (FWHM) X‐ray pulses in the soft X‐ray range at variable polarization. A novel approach consisting of an array of nine off‐axis reflection zone plates is used for a gapless coverage of the spectral range between 410 and 1333 eV at a designed resolution of E/ΔE = 500 and a pulse elongation of only 30 fs. With the upgrade of the ZPM the following was achieved: a smaller focus, an improved spectral resolution and bandwidth as well as excellent long‐term stability. The beamline will enable a new class of ultrafast applications with variable optical excitation wavelength and variable polarization.     

云母1/4波片偏振干涉谱的研究

本文利用岛津UV301－PC分光光计，测定了云母1／4波片的偏振干波谱，该光谱和以往文献中的显著不同。本文对此进行了分析和解释，并由此得出了在考虑吸收的情况下的爱里方程表达形式。该将有助于测定某些晶体的吸光度。     

Recording of PIV images on photothermoplastic plates

In this paper we explore the possibility of utilizing commercially available photothermoplastic plates as recording support in Particle Image Velocimetry (PIV), to allow real time analysis of recorded data. An experimental apparatus has been developed which allows holographic recording and reconstruction of simulated PIV images. We show that double exposed photothermoplastic plates can successfully be analysed provided that a suitable recording/reconstruction scheme is used.     

Triangular arbitrage as an interaction among foreign exchange rates

We first show that there are in fact triangular arbitrage opportunities in the spot foreign exchange markets, analyzing the time dependence of the yen–dollar rate, the dollar–euro rate and the yen–euro rate. Next, we propose a model of foreign exchange rates with an interaction. The model includes effects of triangular arbitrage transactions as an interaction among three rates. The model explains the actual data of the multiple foreign exchange rates well.     

一种诊断复合材料层合板损伤的频响方法

本文首先选取对故障比较敏感,又能反映结构动力学特性的频响函数作为诊断故障的参数。通过计算无损板在给定模态下各单元的模态能量,求得每个单元对该阶模态下全板能量的贡献,并由模态实验得到损伤前后频响函数在各阶共振峰处的变化。分析发现两者之间存在内在联系,从而得到一种分析小损伤位置和范围的新方法。     

片式消声器的设计及其在环境噪声控制中的应用

本文从应用角度，对片式消声器的结构，消声机理，设计原则等作了较为全面的阐述，介绍了应用实例，结合工程实践，提出了一个估算存在气流时消声系数的经验公式。     

关于模糊预度量空间中的三角不等式

在L，R为一般三角模时，给出在模糊预一度量空间中三角不等式成立的一个必要条件，并用其给出模糊度量空间的一个不动点定理。     

Measuring the thickness and refractive index of a thick transparent plate by an unexpanded laser beam

The thickness and refractive index of a thick transparent plate are measured by using an unexpanded HeNe laser beam. The laser beam is incident at different angles onto the plate; and then two reflected beams; from the front and back surfaces; are received on a distant screen: the corresponding separations between them are measured. A theoretical relation between the refractive index; thickness; angle of incidence and separation is derived. This relation is experimentally verified and shows good agreement. The errors in the measured thickness and refractive index are analysed. The method is non-contact; non-destructive and low cost.