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Carlier J.,University Of Technology Of Compigne | Hermes F.,University of Tunis | Moukrim A.,University Of Technology Of Compigne | Ghedira K.,Institute Superieur Of Gestion Of Tunis
Computers and Industrial Engineering | Year: 2010

This paper investigates the one-machine sequencing problem in a workshop where the machine has to satisfy the no-idle constraint, that is, the machine must process jobs without interruption. The objective is to minimize the makespan. Each job has a release date for which it is available for processing on the machine and a delivery time during which it must remain in the system after being processed by the machine. This problem has been studied without adding the no-idle constraint. It is solved in polynomial time, when the preemption of jobs is allowed, applying Jackson's rule. But, when the preemption of jobs is not allowed, it becomes strongly NP-hard. Although, it can be solved in a very short time using Carlier's branch and bound algorithm. Below, we propose to adapt Carlier's branch and bound method in order to calculate an optimal nonpreemptive schedule for the problem when adding the no-idle constraint. © 2010 Elsevier Ltd. All rights reserved.


Chen D.,Beijing University of Technology | Bonis M.,University of Technology of Compigne | Zhang F.,Harbin Institute of Technology | Dong S.,Harbin Institute of Technology
Precision Engineering | Year: 2011

This paper proposes a thermo-mechanical error model of a hydrostatic spindle for a high precision machine tool. By predicting the variation of motion error induced by thermal effects on a machine worktable during machining, this model allows deeper insights into the underlying mechanisms that result in evolutions of the spindle accuracy. The heat power generated in the spindle elements and the coefficients of convection heat transfer over its outer surface have been evaluated. Then, the distribution of temperature and deformation of the spindle have been simulated by a finite element coupled thermo-elastic model, from which the influence on notably spindle stiffness variation was deduced. Experimental measurement of the thrust plate axial displacement under thermal expansion is in close agreement with the computed axial thermal expansion. © 2011 Elsevier Inc.


Masson M.-H.,University of Picardie Jules Verne | Masson M.-H.,French National Center for Scientific Research | Denoeux T.,University Of Technology Of Compigne | Denoeux T.,French National Center for Scientific Research
International Journal of Approximate Reasoning | Year: 2011

In this paper, belief functions, defined on the lattice of intervals partitions of a set of objects, are investigated as a suitable framework for combining multiple clusterings. We first show how to represent clustering results as masses of evidence allocated to sets of partitions. Then a consensus belief function is obtained using a suitable combination rule. Tools for synthesizing the results are also proposed. The approach is illustrated using synthetic and real data sets. © 2010 Elsevier Inc. All rights reserved.


Grimi N.,University Of Technology Of Compigne | Mamouni F.,Sultan Moulay Slimane University | Lebovka N.,University Of Technology Of Compigne | Lebovka N.,Ukrainian Academy of Sciences | And 2 more authors.
Journal of Food Engineering | Year: 2011

The purpose of this study was to compare the effects of pulsed electric field (PEF) on apple juice characteristics (turbidity, polyphenolic content and antioxidant capacities). The pressing was used as a standard method for juice extraction. Experiments were carried out at a constant pressure (P = 3 bar) using a laboratory press cell. Two different methods for PEF application at 400 V/cm were investigated (PEF treatment of whole samples before cutting and PEF treatment of apple slices after cutting). PEF treatment resulted in increase of the juice yield from 44 g/100 g apple (untreated samples) to 58 g/100 g apple (treatment of whole apples) and 64 g/100 g apple (treatment of slices) after 30 min of pressing. The analysis of pH and conductivity showed no significant difference between untreated and PEF-treated samples. However, the total soluble matter content of juice increased after PEF treatment. The obtained turbidity and transmittance data evidence a noticeable improvement of juice clarity for PEF-treated samples. The PEF pre-treatment was accompanied by an increase of the content of polyphenols and intensification of the antioxidant capacities of juice. Most of these effects (juice clarity and content of antioxidants) were more pronounced for the whole treated apples as compared to untreated apples and PEF-treated apple slices. The evolution of apple browning before and after PEF treatment was more pronounced for whole samples. PEF treatment accelerates browning. The obtained data can contribute to the determination of an optimum time for PEF application. The results evidence that PEF-enhanced expression is promising for production of higher quality juices. PEF treatment of whole apples reduces the energy consumption and is advantageous for industrial applications as compared to the treatment of apple slices. PEF combined with pressing can become a good alternative to traditional process. © 2010 Elsevier Ltd. All rights reserved.


Randall R.B.,University of New South Wales | Antoni J.,University of Technology of Compigne
Mechanical Systems and Signal Processing | Year: 2011

This tutorial is intended to guide the reader in the diagnostic analysis of acceleration signals from rolling element bearings, in particular in the presence of strong masking signals from other machine components such as gears. Rather than being a review of all the current literature on bearing diagnostics, its purpose is to explain the background for a very powerful procedure which is successful in the majority of cases. The latter contention is illustrated by the application to a number of very different case histories, from very low speed to very high speed machines. The specific characteristics of rolling element bearing signals are explained in great detail, in particular the fact that they are not periodic, but stochastic, a fact which allows them to be separated from deterministic signals such as from gears. They can be modelled as cyclostationary for some purposes, but are in fact not strictly cyclostationary (at least for localised defects) so the term pseudo-cyclostationary has been coined. An appendix on cyclostationarity is included. A number of techniques are described for the separation, of which the discrete/random separation (DRS) method is usually most efficient. This sometimes requires the effects of small speed fluctuations to be removed in advance, which can be achieved by order tracking, and so this topic is also amplified in an appendix. Signals from localised faults in bearings are impulsive, at least at the source, so techniques are described to identify the frequency bands in which this impulsivity is most marked, using spectral kurtosis. For very high speed bearings, the impulse responses elicited by the sharp impacts in the bearings may have a comparable length to their separation, and the minimum entropy deconvolution technique may be found useful to remove the smearing effects of the (unknown) transmission path. The final diagnosis is based on "envelope analysis" of the optimally filtered signal, but despite the fact that this technique has been used for 40 years in analogue form, the advantages of more recent digital implementations are explained. © 2010 Elsevier Ltd.All rights reserved.


Sbodio M.L.,Hewlett - Packard | Martin D.,SRI International | Moulin C.,University Of Technology Of Compigne
Journal of Web Semantics | Year: 2010

This paper describes a novel approach to the description and discovery of Semantic Web services. We propose SPARQL as a formal language to describe the preconditions and postconditions of services, as well as the goals of agents. In addition, we show that SPARQL query evaluation can be used to check the truth of preconditions in a given context, construct the postconditions that will result from the execution of a service in a context, and determine whether a service execution with those results will satisfy the goal of an agent. We also show how certain optimizations of these tasks can be implemented in our framework. © 2010 Elsevier B.V. All rights reserved.


Risbet M.,University Of Technology Of Compigne | Feissel P.,University Of Technology Of Compigne | Roland T.,INSA Toulouse | Brancherie D.,University Of Technology Of Compigne | Roelandt J.-M.,University Of Technology Of Compigne
Procedia Engineering | Year: 2010

In the context of development of a numerical model, to accurately predict the fatigue life of a structural component, it is fundamental to consider both the initiation stage and the propagation stage of micro-cracks. Such a development requires dedicated experimental tools both to provide the physical understanding needed for designing models and to validate the proposed approaches and models. Thus, this paper presents the experimental means that need to be used for such a purpose. The approach is based on the analysis of displacement field measurements by digital image correlation (DIC) during low-cycle fatigue tests. A specific filtering tool is also presented to minimize the committed errors when derivative operation is performed for strain calculation. Therefore, in this quite recent application of DIC, the reproducibility of the method has to be questioned and validated, with help of some more conventional strain measurements devices. It seems that the experimental conditions have to be carefully controlled, so that the results can be interpreted in terms of mechanical phenomena. © 2010 Published by Elsevier Ltd.


Loginova K.V.,University Of Technology Of Compigne | Loginova K.V.,Ukrainian Academy of Sciences | Vorobiev E.,University Of Technology Of Compigne | Bals O.,University Of Technology Of Compigne | And 2 more authors.
Journal of Food Engineering | Year: 2011

This study describes experiments on pulsed electric field (PEF)-assisted water extraction of sugar from sugar beet using a pilot countercurrent extractor with 14 extraction sections. Cossettes were prepared from sugar beet by industrial knives and PEF treatment of the cossettes was done with electric field strength E varied between 100 and 600 V/cm. The total time of PEF treatment was tPEF = 50 ms. The effects of the main extraction parameters (temperature of extracting water and draft) on the extraction kinetics, as well as on the juice and cossette (pulp) characteristics, were investigated. The temperature of extraction from PEF-treated cossettes was varied from 30 to 70 °C; the draft was varied from 120 to 90%. The principal possibility of cold (at 30 °C) and moderate thermal (50-60 °C) extraction of sucrose from sugar beet cossettes treated by PEF was confirmed on the pilot countercurrent extractor. The purity of the juice obtained by cold and moderate thermal extraction was not lower than the purity of juice obtained by conventional hot water diffusion at 70 °C. The sugar beet pulp can be well exhausted by cold or mild thermal extraction of cossettes treated by PEF. Decrease of draft to 100-90% permitted increasing of the extracted juice concentration, but the cossettes were worse exhausted. The pulp obtained by cold extraction of PEF-treated cossettes had dryness >30%, which was noticeably higher than dryness of the pulp obtained by conventional hot water extraction technique. © 2010 Elsevier Ltd. All rights reserved.


Loginova K.V.,University Of Technology Of Compigne | Loginova K.V.,Ukrainian Academy of Sciences | Lebovka N.I.,University Of Technology Of Compigne | Lebovka N.I.,Ukrainian Academy of Sciences | Vorobiev E.,University Of Technology Of Compigne
Journal of Food Engineering | Year: 2011

This work discusses the temperature effects (T = 30-80 °C) on degradation of colorants and kinetics of their extraction from the red beet both untreated and treated by pulsed electric field (PEF). PEF treatment was done using the trains of monopolar rectangular 100 μs pulses with electric field strength E = 375-1500 V cm-1, and total treatment time t PEF = 0-0.2 s. The degradation of colorants and their extraction were characterized by means of absorbance and electrical conductivity measurements. PEF treatment was found effective for acceleration of the extraction of betalains and reducing the time of extraction. Electroporation was shown to be responsible for intensification of the release of colorants through aqueous extraction. © 2011 Elsevier Ltd. All rights reserved.


Tu Z.,University Of Technology Of Compigne | Ding L.,University Of Technology Of Compigne
Separation and Purification Technology | Year: 2010

This paper focuses on dynamic microfiltration of CaCO3 suspensions conducted on a modified multishaft disk (MSD) laboratory pilot, which permits to use polymeric membranes. In this study, rotating membrane disks were mounted on the upper shaft. The effect of disk rotating speed, transmembrane pressure (TMP), with or without metal disks on the lower shaft was investigated in terms of the permeate flux. The results showed that the permeate flux could be raised significantly in the presence of metal disks. Polymeric membranes were compared to ceramic ones. It seems that the polymeric membrane produces a higher filtrate flux, but it is prone to particle deposit. Consequently, the overlapping disk is more efficient to remove the membrane cake when using a polymeric membrane. Besides, mean shear rates at the membrane were estimated in this MSD module to investigate their influence on the filtrate flux. Shear rates in a filtration module with a disk (RD) rotating near a stationary membrane were also presented for comparison. The results indicated that in both modules the shear rate is the key parameter controlling the filtrate flux. In addition, it was found that less energy was consumed when using ceramic membranes. This difference would be very large in an industrial scale MSD system. © 2010 Elsevier B.V. All rights reserved.

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