Effect of grinding-induced cyclic heating on the hardened layer generation in the plunge grinding of a cylindrical component

This paper discusses the effects of the grinding-induced cyclic heating on the properties of the hardened layer in a plunge cylindrical grinding process on the high strength steel EN26. It was found that a multi-pass grinding brings about a uniform and continuous hardened layer along the circumference of the cylindrical workpiece. An increase of the number of grinding passes, leads to a thicker layer of hardening, a larger compressive residual stress and a deeper plastic deformation zone. Within the plastic deformation zone, the martensitic grains are refined by the thermo-mechanical loading, giving rise to a hardness of 12.5% higher than that from a conventional martensitic transformation. The coupled effects of heat accumulation and wheel wear in the multi-pass grinding are the main causes for the thickening of the hardened layer. A too small infeed per workpiece revolution would result in insufficient grinding heat, and in turn, bring about an undesirable tempered hardened layer and a reduction of its hardness.     

Geo-electrical survey of masonry

The geo-electrical measuring technique is frequently used for restoration purposes. However, this technique as developed in geology cannot be used without adaptations. The structure that is analysed has geometrical boundaries which influence the measurements and can lead to errors in the interpretation if they are not taken into account. This is illustrated by practical and theoretical tests. In an extensive test programme other aspects of the technique are also considered, such as the influence of electrode configuration and of moisture content.     

Joint spectrum management and constrained partial crosstalk cancellation in a multi-user xDSL environment

In modern DSL systems, crosstalk is a major source of performance degradation. Crosstalk cancellation techniques have been proposed to mitigate the effect of crosstalk. However, the run-time complexity of these crosstalk cancellation techniques grows with the square of the number of lines. Therefore one has to be selective in cancelling crosstalk to reduce complexity. Secondly, crosstalk cancellation requires signal-level coordination between transmitters or receivers, which is not always available. Because of accessibility constraints, crosstalk between certain lines cannot be cancelled and so has to be mitigated through spectrum management. After a complexity study, this paper presents a solution for the joint spectrum management and constrained partial crosstalk cancellation problem. The complexity of the partial crosstalk cancellation part of the problem is reduced based on a line selection and user independence observation. However, to fully benefit from these observations, power loading has to be applied in the spectrum management part. We therefore also consider ON/OFF power loading, which has a low complexity and shows only a minor performance degradation compared to normal power loading. The resulting algorithm will be compared to currently available algorithms for independent spectrum management and partial crosstalk cancellation.     

Epoxidation of olefines with PDMS membranes containing zeolite occluded manganese diimine complexes

A new composite catalyst for selective epoxidation of olefins with tert-butyl hydroperoxide (tBHP) is reported. The catalyst contains manganese diimine complexes (cis-Mn bis-2,2′-Bipyridyl), occluded within a NaY zeolite, in turn incorporated in a polydimethylsiloxane membrane (cis-[Mn(bpy)₂]²⁺-NaY-PDMS). The three-step synthesis consists of a Mn²⁺exchange of NaY, ligand sorption to form cis-[Mn(bpy)₂]²⁺-NaY and incorporation of the latter in a PDMS membrane. The major differences between [Mn(bpy)₂]²⁺-NaY as such and occluded in PDMS are observed in the sorption and catalytic characteristics. With the membrane system, the use of a solvent becomes obsolete. Whereas optimal cyclohexene oxidation with [Mn(bpy)₂]²⁺-NaY occurs with hydrogen peroxide in acetone, tBuOOH proves to be a better oxidant for [Mn(bpy)₂]²⁺-NaY-PDMS. The reactions in batch and fed-batch reactors are discussed. A simple regeneration procedure, monitored by FT-IR spectroscopy is proposed.     

A model-free control structure for the on-line tuning of the semi-active suspension of a passenger car

Comfort and road handling of a passenger car can be improved by replacing its passive suspension by a controlled semi-active suspension. The selection of an appropriate control structure is crucial, since it determines the complexity of the control design and parameter tuning process.This paper presents a flexible and transparent model-free control structure based on (1) physical insights in the car and semi-active suspension dynamics used to linearise and decouple the system, and (2) decentralised linear feedback. The resulting controller can be tuned on-line intuitively using a limited number of physically interpretable parameters.The simplicity of the control structure and the absence of any model of either the car or the shock absorber yields that the code of the controller can run on a low-cost DSP with a minimum amount of memory. The evaluation of experienced test-pilots states that the car with tuned controller behaves naturally, yields comfortable ride on a wide variety of calibrated evaluation tracks and yet is well controlled during all handling manoeuvres.     

Modelling of aluminium scrap melting in a rotary furnace

In a typical secondary aluminium process, the scrap feed is charged into a rotary furnace, melting and mixing under a salt layer in the furnace. The complexity in such a pyrometallurgical process is due not only to the high temperature effect and the complex chemical reactions, but also to the highly complex scrap feed with a distributed nature of aluminium types, compositions, sizes, shapes, paintings and other contaminations. In this study, user sub-models, which represent the distributed nature of the scrap feed, were developed and integrated into a computational fluid dynamics (CFD) based process model of a rotary furnace. Aluminium scrap was classified into several groups depending on their properties, e.g., size, establishing a discretized population balance model (PBM). The melting behaviour of aluminium scrap was simulated with the exchange of information between the melting sub-model and the CFD calculations. In addition, the sub-model for scrap burn-off was also developed and integrated in the CFD framework providing distributed burn-off rates. Simulations of the melting process were made to model the flow and thermal phenomena in such a furnace, and the influence of the scrap size, shape and quality, as well as burn-off rate were studied.     

Water management in the Flemish steel industry: the Arcelor Gent case

Steel production is an energy- and water-intensive process: large quantities of water are used for cooling, process and environmental-technical applications. In the mid-1990s, Arcelor Gent, a large integrated carbon steel producing company in Flanders (Belgium), started a number of water-related projects: the existing water infrastructure was adapted: the water from the coke plant was biologically treated; canal water was demineralised using reverse osmosis; waste water from the blast furnaces was neutralised with alkaline water from the steel plant. As a result of these projects, the quantity of discharged waste water was reduced by a factor of 2 (water recycling doubled from a factor of 10 to a factor of 20), and the discharge of pollutants decreased. Also resource consumption decreased: lime used in the steel plant, could be recovered to precipitate Zn in the waste water of the blast furnaces. Arcelor Gent obtained for these projects several Environmental Awards.     

The Cold Chain,one link in Canada’s food safety initiatives

The Cold Chain has always played an important role in food safety within the global market. The Canadian government has recognized it has an important role in the food continuum. In partnership with industry, national voluntary enhanced food safety systems, based on Codex Alimentarius (HACCP) principles, are being developed within Canada. These efforts will contribute towards food safety and will build confidence in foodstuffs grown, prepared and sold at all levels of trade and abroad.