德国屋面工人职业技能培训制度概述

介绍了德国屋面工人职业技能培训制度。在德国,屋面工人职业技能培训由培训公司和政府办的职业学校负责;希望从事屋面行业的人员经3年学徒期培训后,可以继续深造成为屋面技师。     

Generic Pickling and Minimization

This paper presents generic pickling and minimization mechanisms that are provided as services similar to garbage collection. Pickling is used to externalize and internalize data. Minimization means to maximize the sharing in arbitrary data structures. The paper introduces the notion of an abstract store as a formal basis for the algorithms, and analyzes design decisions for the implementation aspects of pickling and minimization. The mechanisms presented here are fully implemented in the Alice programming system.     

Palladium/perovskite/zirconia catalytic premixed fiber burners for efficient and clean natural gas combustion

The present work was aimed at developing and testing – under realistic operating conditions on a specifically assembled pilot plant – a novel generation of catalytic premixed fiber burners for low-environmental-impact natural gas combustion. The adoption of a palladium-LaMnO₃-zirconia catalyst developed on purpose, where zirconia acts as a structural promoter and the noble metal/perovskite synergism is effectively exploited, led to enhanced performances with respect to non-catalyzed burners. In particular, lower CO and NO_x emissions were recorded over a wide field of operating conditions (basically excess of air with respect to the stoichiometric condition and nominal heat power).

Also, the effect of ageing and poisoning induced by sulfur compounds added as odorants in the natural gas network was studied, with promising indications as regards the burners durability: the overall performance, in terms of pollutant emissions, appeared to have slightly improved after prolonged exposure to SO₂ and high temperatures.     

Classifying EEG and ECoG signals without subject training for fast BCI implementation: comparison of nonparalyzed and completely paralyzed subjects.

We summarize results from a series of related studies that aim to develop a motor-imagery-based brain-computer interface using a single recording session of electroencephalogram (EEG) or electrocorticogram (ECoG) signals for each subject. We apply the same experimental and analytical methods to 11 nonparalysed subjects (eight EEG, three ECoG), and to five paralyzed subjects (four EEG, one ECoG) who had been unable to communicate for some time. While it was relatively easy to obtain classifiable signals quickly from most of the nonparalyzed subjects, it proved impossible to classify the signals obtained from the paralyzed patients by the same methods. This highlights the fact that though certain BCI paradigms may work well with healthy subjects, this does not necessarily indicate success with the target user group. We outline possible reasons for this failure to transfer.     

Efficient unbalanced merge-sort

Sorting algorithms based on successive merging of ordered subsequences are widely used, due to their efficiency and to their intrinsically parallelizable structure. Among them, the merge-sort algorithm emerges indisputably as the most prominent method. In this paper we present a variant of merge-sort that proceeds through arbitrary merges between pairs of quasi-ordered subsequences, no matter which their size may be. We provide a detailed analysis, showing that a set of n elements can be sorted by performing at most n⌊logn⌋ key comparisons. Our method has the same optimal asymptotic time and space complexity as compared to previous known unbalanced merge-sort algorithms, but experimental results show that it behaves significantly better in practice.     

ARGES: Radial segregation and helical instabilities in metal halide lamps studied under microgravity conditions in the International Space Station

HID lamps (High-Intensity Discharge) are gaining ground in the lighting industry because of their very high energy efficiency (up to 40%). In these lamps, which are operated in the arc regime and which are contained in a ceramic balloon, filled with argon or xenon, mercury, and salts of various rare earth metals and iodine), de-mixing occurs. This de-mixing is driven by differences in diffusion velocities of molecules and atoms. Furthermore, helical instabilities might occur in the lamp. Both phenomena are severely modified under 1 G conditions: convection will bend a horizontally burning arc channel upwards, and a vertically burning arc channel will exhibit convective cells. This makes it impossible to study these phenomena on the ground. If a proper understanding of these phenomena is to be gained, experiments under microgravity are necessary. The main objectives of the experiment are: (1) determination of the critical factors for the onset of helical instabilities in HID lamps and (2) characterisation of the radial de-mixing processes by radially resolved high-resolution emission spectroscopy. To this end, special hardware has been designed and built which houses a very compact high-resolution spectrometer, a video camera and a caroussel with 20 lamps in it. The lamps are measured consecutively. The experiments have been performed successfully by the Dutch astronaut André Kuipers on board the International Space Station during the Dutch Soyuz Mission “DELTA” on 24 and 25 April 2004. Especially the helical instabilities part yielded immediate and surprising results: the arc channel does bend, but does not rotate under microgravity. This fact is very important in improving the performance of the lamps, especially since the instabilities occur mainly in the most efficient lamps.     

Pin-Contact Behaviour of Composite Sandwich Structures Under Compressive Bearing Load

The aim this research is to investigate the pin-sandwich contact behaviour of some sandwich composites structures when submitted to compressive bearing loads. A preliminary set of flatwise and edgewise compressive tests and three point flexural tests were performed to get information on the mechanical behaviour of the sandwich structures under different load conditions. The influence of two different manufacturing procedures on the bearing strength is evidenced. The experiments show that the bearing loads increase with the pin diameter, while the bearing stress depends in a different way of the pin diameter for the two kind of procedures employed. In addition a simplified numerical model is proposed to evaluate the stress/strain distribution in the sandwich structure under compressive bearing load, by employing a commercial code. The comparison of numerical results with experiments shows the accuracy of the model.     

Calcium ions enclosed in casein phosphopeptide aggregates are directly involved in the mineral uptake by differentiated HT-29 cells

Casein phosphopeptides (CPPs) display the ability to form aggregates with calcium and promote the mineral uptake in models of intestinal cells. The present study aimed to clarify which fraction of calcium, CPPs – bound or free, is directly involved. A commercial preparation of calcium enriched CPPs was employed. The free intracellular calcium was monitored at the single cell level by fura-2 fluorescence. Results showed that calcium enriched CPPs formed aggregates and promoted mineral uptake by the cells at a stable level regardless of the amount of extracellular calcium, indicating that the fraction of calcium bound to CPPs was responsible of the bioactivity. The decalcified CPPs bind free calcium available in solution, form aggregates and promote the mineral uptake by the cells, but are dependent on extracellular calcium.     

Citation Analysis of Cuban Research. Part 1. A Case Study: The Cuban Journal of Agricultural Science

Bibliometric analyses of research in developing countries are interesting for various reasons. The situation of Cuba is rather exceptional. The Cuban Journal of Agricultural Science (CJAS) is the only Cuban research journal, indexed by the Institute of Scientific Information's Web of Science (WoS). We explore the possibilities of a citation analysis for Cuban research publications in general and for those in CJAS in particular. For the period 1988–1999, we find that this journal represents 14% of Cuban research publications, cited in the WoS. We remark that the number of self citations is relatively high and even increases since 1995. The results are classified by disciplines and we use a co-citation matrix to discuss the different observed citation patterns.