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Inspection and maintenance planning: an application of semi-Markov decision processes 总被引:1,自引:1,他引:0
CHRISTOPHE BERENGUER CHENGBIN CHU ANTOINE GRALL 《Journal of Intelligent Manufacturing》1997,8(5):467-476
In this paper, we consider a system which deteriorates stochastically from one time unit to another. The state of the system, which is a continuous random variable, can be observed only by inspection. The goal of this paper is to derive a predictive maintenance policy which indicates, at each inspection and according to the observed value, whether a preventive maintenance is necessary and when the next inspection should be done. The objective is to minimize the long-run average cost incurred by inspections, preventive maintenance and unexpected breakdowns. The problem is modelled by a semi-Markov decision process. Analytical properties are derived, and based on these properties, numerical methods are constructed to compute an optimal policy. 相似文献
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PREDICTION OF SOLIDS CIRCULATION RATE IN THE RISER OF AN INTERNALLY CIRCULATING FLUIDIZED BED (ICFB)
A predictive mathematical model based on pressure drop in the riser of an Internally Circulating Fluidized Bed (ICFB) is developed to predict solids circulation rate (Gs). The values of Gs predicted using the model agree well with the experimental data. The model also predicts well Gs at higher operating temperatures in the riser of an ICFB. 相似文献
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Edible composite films of wheat gluten and lipids: water vapour permeability and other physical properties 总被引:8,自引:0,他引:8
NATHALIE GONTARD† CHRISTOPHE DUCHEZ JEAN-LOUIS CUQ STÉPHANE GUILBERT‡ 《International Journal of Food Science & Technology》1994,29(1):39-50
Edible composite films comprised of wheat gluten as the structural matrix and various concentrations of different lipids as the moisture barrier component were tested for water vapour permeability, dispersion in water, opacity and mechanical properties. the effects of lipids on the functional properties of gluten-based composite films depended on the lipid characteristics and on the interactions between the lipid and the protein structural matrix. Beeswax, a solid and highly hydrophobic lipid, was the most effective lipid for improving moisture barrier properties of films; but these films were opaque, weak and disintegrated easily in water. Combining wheat gluten proteins with a diacetyl tartaric ester of monoglycerides reduced water vapour permeability, increased strength and maintained transparency. 相似文献
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Abstract In the search for more compact air/liquid heat exchangers, one possibility is to increase the heat transfer coefficient and surface area by a decrease of the size of the fluid channels. A practical example could be seen in the air/water cross-flow heat exchangers used in cars. For such exchangers, minimization of the total volume leads to a very thin structure, with a lot of small and short air channels. We have designed and patented a cross-flow heat transfer surface with microchannels that has such a structure and can be manufactured industrially at a reasonable cost by extrusion either in aluminum or in polymers. The thermo-hydraulic performance of the structure has been simulated using standard correlations and CFD codes, and prototypic structures are under investigation to validate simulations. Compared to classical heat exchangers, our design is superior in flexibility and compactness for air/liquid applications. 相似文献
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1Time-scale representation of voiced speech is applied to voice quality analysis, by introducing the Line of Maximum Amplitude
(LoMA) method. This representation takes advantage of the tree patterns observed for voiced speech periods in the time-scale
domain. For each period, the optimal LoMA is computed by linking amplitude maxima at each scale of a wavelet transform, using
a dynamic programming algorithm. A time-scale analysis of the linear acoustic model of speech production shows several interesting
properties. The LoMA points to the glottal closure instants. The LoMA phase delay is linked to the voice open quotient. The
cumulated amplitude along the LoMA is related to voicing amplitude. The LoMA spectral centre of gravity is an indication of
voice spectral tilt. Following these theoretical considerations, experimental results are reported. Comparative evaluation
demonstrates that the LoMA is an effective method for the detection of Glottal Closure Instants (GCI). The effectiveness of
LoMA analysis for open quotient, amplitude and spectral tilt estimations is also discussed with the help of some examples. 相似文献