Dynamic hybrid simulation of batch processes driven by a scheduling module

Simulation is now a CAPE tool widely used by practicing engineers for process design and control. In particular, it allows various offline analyses to improve system performance such as productivity, energy efficiency, waste reduction, etc. In this framework, we have developed the dynamic hybrid simulation environment PrODHyS whose particularity is to provide general and reusable object-oriented components dedicated to the modeling of devices and operations found in chemical processes. Unlike continuous processes, the dynamic simulation of batch processes requires the execution of control recipes to achieve a set of production orders. For these reasons, PrODHyS is coupled to a scheduling module (ProSched) based on a MILP mathematical model in order to initialize various operational parameters and to ensure a proper completion of the simulation. This paper focuses on the procedure used to generate the simulation model corresponding to the realization of a scenario described through a particular scheduling.     

Journey in the <Emphasis Type=Italic>Ostrinia</Emphasis> World: From Pest to Model in Chemical Ecology

The European corn borer Ostrinia nubilalis (ECB; Lepidoptera: Crambidae) is a widely recognized pest of agricultural significance over much of the northern hemisphere. Because of the potential value of pheromone-based control, there has been considerable effort devoted to elucidation of the ECB chemical ecology. The species is polymorphic regarding its female-produced pheromone. Partly because of this feature, over the years the ECB has become a model to study pheromone evolution. This review should assist in identifying new areas of pheromone research by providing an overview of the literature produced on this subject for the ECB since the late 1960’s.     

Microstructural study of aged ferrite powders for sensing layers

Nanosized powders of La_0.80Sr_0.20Fe_0.95Cu_0.05O_3?w were investigated in terms of structural, morphological, chemical and surface properties by using several characterization techniques. The XPS and IR measurements showed the presence of surface hydroxide and carbonates species. After calcination of the powders at 900 °C the amount of carbonates decreased but was still significant. The sensing activity of thick film based on La_0.80Sr_0.20Fe_0.95Cu_0.05O_3?w was tested as a function of relative humidity and the results indicate that (i) after one year of ambient storage the sensing material lost quite completely its sensitivity to humidity, (ii) the sensing activity of the film was mostly re-activated after a thermal treatment at 900 °C for 2 h, and (iii) the huge shift of the detection limit to low RH caused by the presence of 5 mol% Cu is also restored.     

Semiclosed-Cell Mullite Foams: Preparation and Macro- and Micromechanical Characterization

The preparation and characterization of the properties of mullite ceramic foams suitable for diesel exhaust filtration systems are described. Two foams of different cell sizes, 32 and 61 ppi (pores per inch), were prepared from slurries by the replication process with polyurethane sponges as the templates. The microstructure and the dependence of the porosity and the mechanical properties on the preparation and resulting foam cell size and normalized density are discussed. In addition the micro- and macromechanical properties have been characterized using instrumented indentation techniques; with sharp (Berkovich) and small spherical-tipped indenters the hardness and modulus of the dense strut materials have been measured. The macroproperties have been measured with a large sapphire indenter, ∼5 mm radius using a load partial-unloading technique. The latter enables the modulus and the contact pressure versus penetration to be measured. These values are compared with traditional bulk measurements for crushing strength and elastic modulus. The results are discussed in terms of available theoretical treatments of the indentation of brittle porous materials.     

FePO Catalysts for the Selective Oxidative Dehydrogenation of Isobutyric Acid into Methacrylic Acid

This review presents the iron phosphorus oxides used as catalysts for isobutyric acid oxidative dehydrogenation. Research on this catalytic system has been developed in the last decade and many publications have been devoted to this reaction, as it can be a step in a new process of production of methyl methacrylate. We emphasize particularly the nature of the active phase, the active centers, and the role of water and promoters. The mechanistic aspects of the reaction, which corresponds to an extension of the Mars and van Krevelen mechanism with a special role of water partial pressure, are discussed.     

Modification of hydrophobic/hydrophilic properties of Vulcan XC72 carbon powder by grafting of trifluoromethylphenyl and phenylsulfonic acid groups

Carbon supports (glassy carbon and Vulcan XC72 powder) were modified by electrochemical and spontaneous grafting of phenylsulfonic acid (PSA) or trifluoromethylphenyl (TFMP) groups via diazonium ion reduction. The effectiveness of the grafting was confirmed electrochemically, by XPS measurements and elemental analyses. The hydrophobic or hydrophilic character of carbon surfaces was evidenced by measuring the contact angles of drops of different liquids (water, ethylene glycol and glycerol) in heptane. The surface energy was calculated and it was found, for example, that spontaneous grafting of a glassy carbon surface by PSA groups led to an increase by a factor 20 of the surface energy compared with an unmodified glassy carbon surface. The study of the grafting of such groups on XC72 carbon powder indicated that a very low grafting ratio (in wt%) led to a significant change in the macroscopic properties of the powder. Thermogravimetric analysis coupled with mass spectroscopy measurements (TGA-MS) showed that these grafted layers were thermally stable even in the presence of dispersed platinum nanoparticles. It was shown by cyclic voltammetry that the carbon substrate modification did not affect the electrochemical behavior of platinum catalyst, since the same active surface area was determined on Pt-XC72, Pt-PSA-XC72 and Pt-TFMP-XC72 catalysts.     

Real-time spatial processing of sounds for music, multimedia and interactive human-computer interfaces

This paper gives an overview of the principles and methods for synthesizing complex 3D sound scenes by processing multiple individual source signals. Signal-processing techniques for directional sound encoding and rendering over loudspeakers or headphones are reviewed, as well as algorithms and interface models for synthesizing and dynamically controling room reverberation and distance effects. A real-time modular spatial-sound-processing software system, called Spat, is presented. It allows reproducing and controling the localization of sound sources in three dimensions and the reverberation of sounds in an existing or virtual space. A particular aim of the Spatialisateur project is to provide direct and computationally efficient control over perceptually relevant parameters describing the interaction of each sound source with the virtual space, irrespective of the chosen reproduction format over loudspeakers or headphones. The advantages of this approach are illustrated in practical contexts, including professional audio, computer music, multimodal immersive simulation systems, and architectural acoustics.