Stress-Strain State in the Zone of Load Transfer in a Composite Specimen under Uniaxial Tension

The stress-strain state in the zone of load transfer in a uniaxially stretched specimen made of a unidirectional epoxy carbon-fiber-reinforced plastic (CFRP) is investigated. A parametric analysis of the influence of geometric and mechanical characteristics of the specimen on its stress-strain state is performed by means of finite-element modeling. The parameters allowing us to significantly reduce the dangerous concentration of transverse and tangential stresses are revealed. The mechanical tensile characteristics of a high-strength pultruded unidirectional CFRP are determined experimentally, and the size effect of its strength is estimated.     

ATLAS electromagnetic calorimetry and performance of electron/photon detection

The European Physical Journal C - The design constraints and the target physics performance of the ATLAS Electromagnetic Calorimeter are reviewed, and the construction status is summarized....     

K X-ray production cross sections for 40-180 keV protons

Considering the importance of the X-ray production cross sections for the determination of the element concentrations in a given material, we have measured them experimentally for Al Si, Sc, Ti, V, Fe, Co, Ni and Cu bombarded by protons with energies ranging from 40 to 180 keV. This revised version was published online in July 2006 with corrections to the Cover Date.     

Index Heuristics for Multiclass M/G/1 Systems with Nonpreemptive Service and Convex Holding Costs

We consider the optimal service control of a multiclass M/G/1 queueing system in which customers are served nonpreemptively and the system cost rate is additive across classes and increasing convex in the numbers present in each class. Following Whittle's approach to a class of restless bandit problems, we develop a Langrangian relaxation of the service control problem which serves to motivate the development of a class of index heuristics. The index for a particular customer class is characterised as a fair charge for service of that class. The paper develops these indices and reports an extensive numerical investigation which exhibits strong performance of the index heuristics for both discounted and average costs.     

A novel approach to the acoustic characterisation of porous road surfaces

Porous road surfaces offer an effective means of reducing the generation and propagation of noise from road traffic. However, the porosity of these surfaces can deteriorate over time, leading to a reduction in their noise reducing properties. Efficient methods are therefore required for monitoring this performance. Existing techniques for performing in-situ measurements of acoustic absorption are unsuitable for use within the traffic stream. Static measurements using time domain Maximum Length Sequence (MLS) based techniques have been demonstrated to offer advantages over traditional techniques, presenting the opportunity for measurements under dynamic conditions. This paper describes the design of a system for carrying out dynamic MLS-based measurements. Results are presented which demonstrate that stable dynamic measurements can be carried out at speeds of up to 30 km/h.     

Untersuchungen zur Wechselwirkung von gasf?rmigem molekularem Iod mit Silberoberfl?chen mittels XPS und AES

Summary The adsorption of gaseous molecular iodine on clean silver surfaces proceeds in the first stage by dissociative chemisorption. After the formation of half a monolayer of chemisorbed iodine atoms the formation of silver iodide begins, which forms a very regular overlayer on top of the substrate. Both iodine species can be distinguished due to a difference in chemical shift of the M₄N₄, ₅N₄, ₅-Auger transitions. After completion of this overlayer further iodine uptake is slowed down significantly. Above an overlayer thickness of about 10 nm a further progress of the reaction cannot be followed anymore due to the limited information depth of XPS.     

Construction algorithms for polynomial lattice rules for multivariate integration

We introduce a new construction algorithm for digital nets for integration in certain weighted tensor product Hilbert spaces. The first weighted Hilbert space we consider is based on Walsh functions. Dick and Pillichshammer calculated the worst-case error for integration using digital nets for this space. Here we extend this result to a special construction method for digital nets based on polynomials over finite fields. This result allows us to find polynomials which yield a small worst-case error by computer search. We prove an upper bound on the worst-case error for digital nets obtained by such a search algorithm which shows that the convergence rate is best possible and that strong tractability holds under some condition on the weights.

We extend the results for the weighted Hilbert space based on Walsh functions to weighted Sobolev spaces. In this case we use randomly digitally shifted digital nets. The construction principle is the same as before, only the worst-case error is slightly different. Again digital nets obtained from our search algorithm yield a worst-case error achieving the optimal rate of convergence and as before strong tractability holds under some condition on the weights. These results show that such a construction of digital nets yields the until now best known results of this kind and that our construction methods are comparable to the construction methods known for lattice rules.

We conclude the article with numerical results comparing the expected worst-case error for randomly digitally shifted digital nets with those for randomly shifted lattice rules.