Robust load balancing under traffic uncertainty��tractable models and efficient algorithms

Routing configurations that have been optimized for a nominal traffic scenario often display significant performance degradation when they are subjected to real network traffic. These degradations are due to the inherent sensitivity of classical optimization techniques to changes in model parameters combined with the significant traffic variations caused by demand fluctuations, component failures and network reconfigurations. In this paper, we review important sources for traffic variations in data networks and describe tractable models for capturing the associated traffic uncertainty. We demonstrate how robust routing settings with guaranteed performance for all foreseen traffic variations can be effectively computed via memory efficient iterative techniques and polynomial-time algorithms. The techniques are illustrated on real data from operational IP networks.     

Automatic laser-based identification for UF6 cylinders

We present a laser item identification system (L2IS), installed in a real facility on trial, that is capable of automatically monitoring all transfers of uranium hexafluoride (UF₆) cylinders between different process areas. Each cylinder has a unique ‘fingerprint’ represented by the 3D micro-structure of its surface which remains intact even under extreme environmental conditions. L2IS automatically identifies each cylinder through exploring the 3D frontal surface acquired by the laser scanner. The system is composed of a portable unit (operated in attended mode) and a fixed installed unit (operated without inspector presence). The efficiency and accuracy of our identification system were evaluated on a large dataset acquired during several years including a full year of field testing.     

Isocyanates,aminoisocyanates and amines from fires—a screening of common materials found in buildings

Isocyanates, aminoisocyanates and amines were quantified from the combustion of 24 different materials or products typically found in buildings. Small‐scale combustion experiments were conducted in the cone calorimeter, where generally well‐ventilated combustion conditions are attained. Measurements were further made in two different full‐scale experiments. Isocyanates and amino‐compounds were sampled using an impinger‐filter sampling system with a reagent solution of di‐n‐butylamine in toluene. Filter and impinger solution were analysed separately using LC‐MS technique. Further the particulate distribution in the smoke gases was determined by impactor technique, and selected gaseous compounds quantified by FTIR. It was found in the small‐scale that isocyanates were produced from the majority of the materials tested. The highest concentration was found for glass wool insulation, and further high concentrations were found for PUR products, particleboard, nitrile rubber and melamine. Lower concentrations were found for wood and cable‐products. Amino‐isocyanates and amines were generally found from PUR products only. The distribution of isocyanates between the particulate‐ and fluid phases varied for the different materials and a tendency to enrichment of particles was seen for some of the materials. Further, when comparing the potential health hazard between isocyanates and other major fire gases (based on NIOSH IDLH‐values) it was found that isocyanates in several cases represented the greatest hazard. Copyright © 2003 John Wiley & Sons, Ltd.     

德国钢铁工业空气质量控制

到目前为止,在德国管理钢铁公司空气质量控制工作发展的主要管理文件是联邦排放物控制法及关于空气质量控制的补充技术说明(TA Luft).TA Luft法规,最近于2002年进行了修订,具体包括从预防角度而明确设立的总的及与工厂有关的排放限度,排放目标和将现存的工厂升级到目前技术水平的时间限制.这些条款由许多联邦州的政府当局统一执行,已经使德国全国范围的空气质量控制几乎同时达到一个高水平.报告描述了德国钢铁工业和Duisburg地区Thyssenkrupp Stahl的结构性发展,以及在该地区已生效的相关空气质量控制措施.具有里程碑意义的事件包括生产方法的变化,吹氧工艺的引入,辅助除尘技术的应用和一致推广,CO2排放控制工作和一些方面的发展(如炼焦技术方面).为控制PCDD/PCDF排放而进行的吸附基烧结厂废气净化及含铁残余物如沉积粉尘、污泥的处理.到目前为止已获得的多层经验,既有肯定的也有否定的,指出需要加强技术和管理方面的国际合作.     

Transformation approach to numerically integrating PDEs by means of WDF principles

As has been shown, attractive methods for numerically integrating partial differential equations (PDEs) resulting from physical problems can be obtained by simulating the actual physical passive (conservation of energy) dynamical system by means of a discrete passive dynamical system, and this in such a way that the full parallelism and the exclusively local nature of the interconnections (principle of action at proximity) are preserved. An alternative approach for developing such methods is presented which, while still using principles of the same type as those on which multidimensional wave digital filters (WDFs) are based, involves appropriate transformations of the original coordinates of the physical problem at hand. This alternative approach is not only easier to apply than the one referred to above but also more general; it is illustrated on the one hand by the same examples as those that have been used for the other approach, and on the other by showing the applicability to Maxwell's equations.     

The effects of selected aldehydes, ketones and carboxylic acids on off-flavours in water

The effects of selected aldehydes, ketones and carboxylic acids on the development of off‐flavours in water were studied. Combinations of hexanal, octanal, 2‐octanone, 5‐nonanone, hexanoic acid and nonanoic acid were rated by the off‐flavour intensities they created in water at concentrations just at or below the threshold value of each analyte. Two different sensory panels evaluated the off‐flavours induced by different combinations of the analytes. The observations of the two panels agreed well. From these studies, it could be concluded that aldehydes play an important role in the development of off‐flavours intensities in water. There were synergistic effects between aldehydes and ketones, as well as between aldehydes and carboxylic acids. Small amounts of aldehydes and carboxylic acids – well below their respective threshold values – caused an increase in the off‐flavour intensity. No synergism between ketones and carboxylic acids could be observed.     

A Molecular Perspective on the d-Band Model: Synergy Between Experiment and Theory

The d-band model of Hammer and Nørskov (Nature 376:238, 1995 [3]) relating adsorption energies to the d-band position, and the adsorption energies to barriers in catalytic reactions, has been extremely successful in predicting reactivities and catalysts. In the present contribution we review recent combined experimental and theoretical work on chemical bond-formation at surfaces. We focus on the adsorbate and how the adsorbate electronic structure can be rehybridized through mixing with unoccupied states to generate the radical state, real or virtual, that can then form electron pairs with the metal d-states, as described by the d-band model. We discuss five important bonding situations: (i) atomic radical, (ii) diatomics with unsaturated π-systems (Blyholder model), (iii) unsaturated hydrocarbons (Dewar–Chatt–Duncanson model), (iv) lone–pair interactions, and (v) saturated hydrocarbons (physisorption). Where the d-band model predicts trends along the series of transition metals, the present work provides intuitive tools for predicting trends among different adsorbates.