Towards a new schedulability technique of real-time systems modeled by P-time Petri nets

In this paper, a novel schedulability analysis technique of real-time systems is presented. The developed approach is based on the consideration of the reachability graph of the (untimed) underlying Petri net of the studied model. The schedulability analysis is then conducted in two steps. Once a feasible firing sequence (called occurrence sequence) is highlighted, this sequence is then described under an algebraic form of type Ax?≤?b. The particular features of matrix A lead to a bimonotone linear inequality system. A bimonotone linear inequality is a linear inequality with at most two nonzero coefficients that are of opposite signs (if both different from zero). Thus, deciding whether a firing sequence is schedulable or not takes the form of the solution of a single-source shortest path problem which can be polynomially solved via the Bellman–Ford algorithm.     

Exploitation of patent information in R&D output analysis for policymaking

Scientometrics - This paper provides an insight into the growing importance and conditions of studying R&D output and impacts as well as the internationalisation of R&D. Focusing on...     

Diffusion coefficients of additives in polymers. I. Correlation with geometric parameters

Diffusion coefficients of a broad range of molecules with molecular weight ranging from 100 to 800 g/mol have been measured in polypropylene, by solid/solid contact methods (without liquid contact), at 40°C. The behaviors of the different molecules are compared to those of linear alkanes. The diffusion coefficients are correlated to parameters describing size, shape, and flexibility of the molecules. The concept of weighted fractionated volume is introduced using molecular modeling. It enables the classification of the molecules according to modes of molecule displacement (crawling, jumps, or dual mode). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2422–2433, 2001     

Transposition of an Exothermic Reaction From a Batch Reactor to an Intensified Continuous One

The implementation of chemical syntheses in a batch or semi-batch reactor is generally limited by the removal or the supply of heat. A way to enhance thermal performances is to develop multifunctional devices like heat exchanger/reactors. In this work, a novel heat exchanger/reactor is characterized in terms of residence time, pressure drops, and thermal behavior in order to estimate its capacities to perform an exothermic reaction: the oxidation of sodium thiosulfate by hydrogen peroxide. Experimental results highlight the performances of the heat exchanger/reactor in terms of intensification, which allows the implementation of the oxidation reaction at extreme operating conditions. These conditions are finally compared to the ones of a classical batch reactor.     

Prediction of the thermal conductivity anisotropy of Si nanofilms. Results of several numerical methods

The purpose of this work is to predict the in-plane and cross-plane thermal properties of crystalline silicon films. Several thicknesses from 20 nm to 6 μm and mean temperatures between 20 and 500 K have been investigated. Heat transport properties in silicon films have been studied through three different techniques: a semi-analytical method based upon the Kinetic Theory, a deterministic solution of the Boltzmann Transfer Equation (BTE) through the Discrete Ordinate Method and a statistical handling of the BTE by means of Monte Carlo Method. Each technique requires a model for the bulk material dispersion curves and the collision times of the different scattering processes. The three techniques have been validated through their correct prediction of silicon bulk thermal conductivity. Comparisons with in-plane thermal conductivity calculations and measurements have been also discussed. Thus, the cross-plane thermal conduction properties have been predicted. The expected temperature and thickness variations of the thermal conduction properties have been observed: the cross-plane thermal conduction appears to be less efficient than the in-plane thermal conduction, which proves that a significant anisotropy exists.     

Two-step water splitting thermochemical cycle based on iron oxide redox pair for solar hydrogen production

This study deals with solar hydrogen production from the two-step iron oxide thermochemical cycle (Fe₃O₄/FeO). This cycle involves the endothermic solar-driven reduction of the metal oxide (magnetite) at high temperature followed by the exothermic steam hydrolysis of the reduced metal oxide (wustite) for hydrogen generation. Thermodynamic and experimental investigations have been performed to quantify the performances of this cycle for hydrogen production. High-temperature decomposition reaction (metal oxide reduction) was performed in a solar reactor set at the focus of a laboratory-scale solar furnace. The operating conditions for obtaining the complete reduction of magnetite into wustite were defined. An inert atmosphere is required to prevent re-oxidation of Fe(II) oxide during quenching. The water-splitting reaction with iron(II) oxide producing hydrogen was studied to determine the chemical kinetics, and the influence of temperature and particles size on the chemical conversion. A conversion of 83% was obtained for the hydrolysis reaction of non-stoichiometric solar wustite Fe_(1−y)O at 575 °C.     

Is correspondence reflected in the author position? A bibliometric study of the relation between corresponding author and byline position

Bibliometric indicators are increasingly used to fund and evaluate scientific research. Since the number of authors in a paper and the number of has increased it is difficult to determine the individual contribution of authors. Suggested approaches include the study of author position or the corresponding author. Our findings show that the corresponding author is most likely to appear first and then last in the byline. The results are dependent on number of authors in a paper and national differences exist. This underscores the need to take into account both the number of authors on a paper and their position in the byline to be accurate when measuring author contribution.     

A new adaptive procedure for using chemical probes to characterize mixing

The iodide–iodate chemical probe method is modified by a novel adaptive procedure to investigate the mixing abilities of two compact curved-duct reactors. Both reactors have a rectangular cross section; the first has smooth curvature (called the wavy duct) and the second has sharper bends (zigzag duct). In the conventional procedure, this method is used to characterize local micro-mixing, and for all experiments (for different Reynolds numbers and injection points) the reagent initial concentrations are kept at the same values. Even with wall injection, the selectivity of the chemical system is generally improved by increasing the flow Reynolds number. Nevertheless, two limitations encountered in using chemical probes (with the conventional protocol) to characterize the mixing abilities of the present reactors that prevent the conventional protocol of the chemical probe from discriminating between the mixing abilities of the two mockups. First, the duct walls are corrugated, so that the wall injection used to measure local micro-mixing is affected by the wall roughness, independently of the Reynolds number. Second, the flow Reynolds numbers are relatively low due to the small size of the duct sides, so that the measurements are inevitably hindered by meso-mixing effects. The challenge is thus to adapt the chemical method for characterizing the global mixing, by enlarging the measurement volume so as to capture and take into account all mixing scales. In the new adaptive procedure, the kinetics of the second reaction are adjusted in such a way as to impose the same reactive volume for different Reynolds numbers, leading to more relevant results for the segregation index X_S. Experimental results reveal that the mixing performance of the zigzag channel as assessed by this method is slightly above that of the wavy one. Finally, the segregation index in both reactors is related to the mixing time t_m by using a physical model in the literature.