An integration architecture for the automation of a continuous production complex

The development of integrated automation systems for continuous production plants is a very complicated process. A variety of factors must be taken into account, such as their different components (e.g., production units control systems, planning systems, financial systems, etc.), the interaction among them, and their different behavior (continuous or discrete). Moreover, the difficulty of this process is increased by the fact that each component can be viewed in a different way depending on the kind of decisions to be made, and its specific behavior. Modeling continuous production complexes as a composition of components, where, in turn, each component may also be a composite, appears to be the simplest and safest way to develop integrated automation systems. In order to provide the most versatile way to develop this kind of system, this work proposes a new approach for designing and building them, where process behavior, operation conditions and equipment conditions are integrated into a hierarchical automation architecture.     

Supervisory control design based on hybrid systems and fuzzy events detection. Application to an oxichlorination reactor

This paper presents a supervisory control scheme based on hybrid systems theory and fuzzy events detection. The fuzzy event detector is a linguistic model, which synthesizes complex relations between process variables and process events incorporating experts' knowledge about the process operation. This kind of detection allows the anticipation of appropriate control actions, which depend upon the selected membership functions used to characterize the process under scrutiny. The proposed supervisory control scheme was successfully implemented for an oxichlorination reactor in a vinyl monomer plant. This implementation has allowed improvement of reactor stability and reduction of raw material consumption.     

Interaction of time-harmonic SH waves with a crack-like inclusion: edge region analysis

Elastodynamic stress concentration near the tips of a crack-like inclusion of finite length generated by the diffraction of high-freqency time-harmonic SH waves is analyzed. It is shown that the stress intensity factors at the tips of inclusion are provided by the fields describing the solution of the static boundary value problem for a semi-infinite strip and edge waves travelling between the two inclusion tips. The solution to the problem is expressed in a closed form that is computationally effective and yields accurate results in the resonance region of dimensionless wave numbers. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effective control of Listeria monocytogenes by combination of nisin formulated and slowly released into a broth system

In order to identify conditions for efficient food preservation by nisin, the sensitivity of Listeria monocytogenes to this preservative was studied under the following three model conditions: (1) the instantaneous addition of nisin into broth medium to simulate the formation of nisin in foods, (2) the slow delivery of nisin solution into broth medium using a pump to simulate the slow release of nisin from packaging materials to foods, (3) a combination of the two delivery methods. Based on the following results, we conclude that the antimicrobial effectiveness of nisin strongly depends on its mode of delivery. The instantaneous and slow methods for adding nisin inhibited L. monocytogenes, but over time of exposure, L. monocytogenes developed tolerance to nisin. Our data indicate that cells treated with instantaneously added nisin developed resistance to higher concentrations of nisin (200 IU/ml), compared to cells treated with slowly added nisin at the same total amount of the antimicrobial. Further studies indicated that nisin-tolerant cells recovered from treatments in which 200 IU/ml nisin was added instantaneously were likely to be mutants, which became resistant to the bacteriocin. In contrast, when 200 IU/ml of the antimicrobial was added slowly to the cells, only a temporary tolerance was developed; these cells became nisin-sensitive after passage through nisin-free medium. Due to the development of nisin-resistant cells, excessive amounts of nisin in the model system did not further inhibit L. monocytogenes. These results signify that excess nisin in foods does not necessarily improve the efficiency of controlling L. monocytogenes. Our data suggest that the combination of packaging material containing nisin used in conjunction with nisin-containing foods will provide the most effective means of preventing L. monocytogenes growth.     

Plastic deformation of invar alloys

Heavy cold-rolling (95% reduction) of a 64Fe36Ni Invar alloy results in a decrease in magnetization and magnetic hyperfine field at the Fe nucleus, and an increase in electrical resistivity and x-ray line width. These changes are explained by a transition of iron atoms from a high volume-high spin electronic configuration to a low volume-low spin configuration during the deformation process.     

Equilibrium shapes and quasi-static formation of bubbles at submerged orifice

A detailed analysis of the effect of chamber volume, orifice radius, orifice submergence and contact angle on quasi-static formation of bubbles is presented. It is shown, that many aspects of slow bubble formation, involving phenomena leading to various modes of the bubble release, as well as the maximum orifice diameter which sustains a bubble at equilibrium, can be explained on the basis of information on equilibrium shapes and conditions. Scaling rules enabling adoption of results for water to other liquids are also presented.     

Typical models: minimising false beliefs

A knowledge system S describing a part of real-world does, in general, not contain complete information. Reasoning with incomplete information is prone to errors since any belief derived from S may be false in the present state of the world. A false belief may suggest wrong decisions and lead to harmful actions. So, an important goal is to make false beliefs as unlikely as possible. This work introduces the notions of typical atoms and typical models, and shows that reasoning with typical models minimises the expected number of false beliefs over all ways of using incomplete information. Various properties of typical models are studied, in particular, correctness and stability of beliefs suggested by typical models, and their connection to oblivious reasoning.     

Hydrogen effects on the spall strength and fracture characteristics of amorphous Fe-Si-B alloy at very high strain rates

A novel approach is suggested, using laser-induced shock wave measurements to estimate the effects of cathodic hydrogen charging on the mechanical properties and fracture characteristics of materials. This approach is applied to (1) determine the dominant mechanism of hydrogen embrittlement (HE) in an amorphous Fe₈₀B₁₁Si₉ alloy; and (2) estimate the effects of the high pressures involved in cathodic charging. The dynamic spall strength of an amorphous Fe₈₀B₁₁Si₉ alloy shocked before and after hydrogenation by a high-power laser to very high pressures (tens of giga Pascals) is measured. The dynamic spall strength of crystalline iron is measured as well for comparison. An optically recording velocity interferometer system (ORVIS) is used to measure the profile of the free surface velocity in time. The spall strength and the strain rate are calculated from the measurement of the free surface velocity as a function of time. Fracture characteristics are studied by scanning electron microscopy (SEM). The main conclusions are (1) the most reasonable mechanism of HE in the amorphous Fe-Si-B alloy is the high-pressure bubble formation; (2) the high pressures involved in cathodic hydrogen charging or laser-induced shock waves measurements may have similar effects on fracture characteristics; and (3) at very high strain rates, the spall strength is determined mainly by the interatomic bonds.     

ATEC: automatic evaluation of machine translation via word choice and word order

We propose a novel metric ATEC for automatic MT evaluation based on explicit assessment of word choice and word order in an MT output in comparison to its reference translation(s), the two most fundamental factors in the construction of meaning for a sentence. The former is assessed by matching word forms at various linguistic levels, including surface form, stem, sound and sense, and further by weighing the informativeness of each word. The latter is quantified in term of the discordance of word position and word sequence between a translation candidate and its reference. In the evaluations using the MetricsMATR08 data set and the LDC MTC2 and MTC4 corpora, ATEC demonstrates an impressive positive correlation to human judgments at the segment level, highly comparable to the few state-of-the-art evaluation metrics.