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1.
Dynamic scheduling for multi-site companies: a decisional approach based on reinforcement multi-agent learning 总被引:1,自引:0,他引:1
N. Aissani A. Bekrar D. Trentesaux B. Beldjilali 《Journal of Intelligent Manufacturing》2012,23(6):2513-2529
In recent years, most companies have resorted to multi-site or supply-chain organization in order to improve their competitiveness and adapt to existing real conditions. In this article, a model for adaptive scheduling in multi-site companies is proposed. To do this, a multi-agent approach is adopted in which intelligent agents have reactive learning capabilities based on reinforcement learning. This reactive learning technique allows the agents to make accurate short-term decisions and to adapt these decisions to environmental fluctuations. The proposed model is implemented on a 3-tier architecture that ensures the security of the data exchanged between the various company sites. The proposed approach is compared to a genetic algorithm and a mixed integer linear program algorithm to prove its feasibility and especially, its reactivity. Experimentations on a real case study demonstrate the applicability and the effectiveness of the model in terms of both optimality and reactivity. 相似文献
2.
Detection of Virulence Genes and Growth Potential in Listeria monocytogenes Strains Isolated from Ricotta Salata Cheese
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Valentina Coroneo Valentina Carraro Nadhem Aissani Adriana Sanna Alessandra Ruggeri Sara Succa Barbara Meloni Antonella Pinna Clara Sanna 《Journal of food science》2016,81(1):M114-M120
Ricotta Salata is a traditional ripened and salted whey cheese made in Sardinia (Italy) from sheep's milk. This product is catalogued as ready‐to‐eat food (RTE) since it is not submitted to any further treatment before consumption. Thus, foodborne pathogens, such as Listeria monocytogenes, can represent a health risk for consumers. In September 2012, the FDA ordered the recall of several batches of Ricotta Salata imported from Italy linked to 22 cases of Listeriosis in the United States. This study was aimed at evaluating the presence and virulence properties of L. monocytogenes in 87 samples of Ricotta Salata produced in Sardinia. The ability of this product to support its growth under foreseen packing and storing conditions was also evaluated in 252 samples. Of the 87 samples 17.2% were positive for the presence of L. monocytogenes with an average concentration of 2.2 log10 cfu/g. All virulence‐associated genes (prfA, rrn, hlyA, actA, inlA, inlB, iap, plcA, and plcB) were detected in only one isolated strain. The Ricotta Salata samples were artificially inoculated and growth potential (δ) was assessed over a period of 3 mo. The value of the growth potential was always >0.5 log10 cfu/g under foreseen packing and storing conditions. This study indicates that Ricotta Salata supports the L. monocytogenes growth to levels that may present a serious risk to public health, even while stored at refrigeration temperatures. 相似文献
3.
Thérèse Barbier Sarra Aissani Nicolas Weber Cédric Pasquier Jacques Felblinger 《Magma (New York, N.Y.)》2018,31(5):677-688
Purpose
To evaluate the function of an active implantable medical device (AIMD) during magnetic resonance imaging (MRI) scans. The induced voltages caused by the switching of magnetic field gradients and rectified radio frequency (RF) pulse were measured, along with the AIMD stimulations.Materials and methods
An MRI-compatible voltage probe with a bandwidth of 0–40 kHz was designed. Measurements were carried out both on the bench with an overvoltage protection circuit commonly used for AIMD and with a pacemaker during MRI scans on a 1.5 T (64 MHz) MR scanner.Results
The sensor exhibits a measurement range of?±?15 V with an amplitude resolution of 7 mV and a temporal resolution of 10 µs. Rectification was measured on the bench with the overvoltage protection circuit. Linear proportionality was confirmed between the induced voltage and the magnetic field gradient slew rate. The pacemaker pacing was recorded successfully during MRI scans.Conclusion
The characteristics of this low-frequency voltage probe allow its use with extreme RF transmission power and magnetic field gradient positioning for MR safety test of AIMD during MRI scans.4.
Jae Yong Jung Taous Khan Joong Kon Park Ho Nam Chang 《Korean Journal of Chemical Engineering》2007,24(2):265-271
In order to improve bacterial cellulose (BC) production yield by increasing the cell density, a new fermentation system using
a spin filter was developed and its performance characteristics were tested. Fermentations were carried out in a fermenter
equipped with a 6 flat-blade turbine impeller and a spin filter consisting of a cylinder surrounded by stainless steel mesh
and whose stainless steel bottom was attached to the agitator shaft. This new fermentation assembly was tested under different
experimental conditions for BC production by Gluconacetobacter hansenii PJK. In periodical perfusion culture without pH control,
the BC production and the total cell mass increased with the culture time to 3.07 and 5.65 g/L, respectively, at 140 h of
cultivation. The BC production was also tested at adjusted pH and pH 5 was found optimum for maximum BC production. At pH
5, in periodical perfusion culture, the BC production and the total cell mass reached to 4.57 and 11.52 g/L, respectively,
after 140 h of cultivation. This amount of BC production was 2.9 times higher than that obtained in a conventional jar fermenter.
The productivity improved and was 0.044 g/L·h at 68 h of cultivation. 相似文献
5.
Saliha Gachi Aissani Mouloud Baudin Thierry Helbert Anne.Laure Brisset François Gautrot Sébastien Mathon Marie-Hélène Bradai Djamel Boubenider Fouad 《Russian Journal of Non-Ferrous Metals》2020,61(5):523-533
Russian Journal of Non-Ferrous Metals - The microstructure and texture of 7075-T6 FSW weld with optimal parameters are investigated using optical microscopy, electron back scatter diffraction and... 相似文献
6.
Omer Shezad Salman Khan Taous Khan Joong Kon Park 《Korean Journal of Chemical Engineering》2009,26(6):1689-1692
The current study investigated fed-batch cultivation for the increased productivity of bacterial cellulose (BC) sheets by
Gluconacetobacter hansenii PJK in static conditions using chemically defined medium and waste from beer fermentation broth. Fermentations were carried
out in a 3 L jar fermenter without any impeller for 30 days. In the proposed fed-batch cultivation, 500 mL of the medium was
initially inoculated with pre-culture in a jar fermenter while a fresh medium was fed periodically. BC production was also
done by using batch cultivation which was used as a control for comparison. The results obtained revealed an overall of 2–3
times increase in BC production in fed-batch cultivation compared to batch cultivation after 30 days of cultivation. During
these experiments, it was found that waste from beer fermentation broth is a superior medium for the BC production using fed-batch
cultivation. The production of water soluble oligosaccharides as useful by-products was also monitored during these investigations.
Fed-batch cultivation and waste from beer fermentation was also found superior for the production of these by-products. According
to literature search and to the best of our knowledge, it is the first report of using fed-batch cultivation for BC production
in static conditions. 相似文献
7.
A successful enantioseparation of d,l-phenylalanine (Phe) was achieved for the first time by using d-Phe imprinted P(MAA-co-EGDMA) microbeads as HPLC stationary phase. The d-Phe imprinted microbeads were prepared by a novel modified suspension polymerization method without derivatization of the water-soluble template molecule. This preparation method was employed in order to capture template molecules in organic phase droplets during polymerization. The prepared d-Phe imprinted P(MAA-co-EGDMA) microbeads were packed into an empty stainless steel column, which was used for the separation of the Phe enantiomers. The selection of a suitable mobile phase, mobile phase composition, pH and flow rate were investigated for determining the best resolution of the Phe enantiomers. Baseline separation was achieved using an organic–aqueous buffer (EtOH–acetate buffer) solution as a mobile phase. Separation factors of more than 2.56, with a resolution of 1.38, were obtained with a mobile phase containing 9–18% (v/v) EtOH in a 0.030 M acetate buffer solution. d-Phe imprinted microbeads were superior to the majority of the reported molecularly imprinted polymers with respect to chiral separation abilities. The column backpressure was less than 300 psi. 相似文献
8.
Mamoun Fellah Linda Aissani Mohammed Abdul Samad Said Mechacheti Mohamed Zine Touhami Alex Montagne 《金属精饰学会汇刊》2017,95(5):261-268
Binary Cr-N, Zr-N and Cr-Zr-N films were synthesised using a R.F. reactive magnetron sputtering technique by co-sputtering Cr and Zr. The crystalline structure, morphology, mechanical and tribological properties of the films as a function of Zr content were characterised by X-ray diffraction, microanalysis X (WDS, EDS), X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, nanoindentation, scratch adhesion and pin-on-disc sliding wear tests. The residual stress was calculated with the Stoney formula. The Cr-Zr-N films exhibit a two-phase microstructure, containing a cubic (CrN, ZrN) with hexagonal (Cr2N, Zr2N) phases, as shown by X-ray diffraction. As the Zr content increased, a columnar and compact structure is developed with a low surface roughness. The results reveal that the mechanical and tribological properties of the films were found to depend on the Zr content and the hardness (maximum 26.3?GPa) is greatly improved in comparison with CrN and ZrN films, especially at 31?at.-% Zr. In the scratch test, the hardest film (Cr0.18Zr0.31N0.47) exhibited an adhesive failure at Lc2?=?34.3?N. 相似文献
9.
Task Assignment in distributed server systems focuses on the policy that assigns the tasks reached these systems in order to improve the response time. These tasks, generally, have the property that there is a tiny fraction (about 3%) of the large tasks that makes half (50%) of the total load. However, this property creates additional problems: the large tasks make the load difficult to balance among the servers, and the small tasks will be delayed by the large ones when they are in the same queue. In this paper, we propose a new policy for the Web clusters that we call Partitioning Large Tasks (PLT) and which deals with these problems mostly under a high traffic demand and a high variability of task sizes. PLT partitions each large task into fragments and assigns them to be processed in a parallel way and completing at the same time to improve the mean response time, and separates the small tasks from the large tasks to avoid being delayed. Performance tests show a significantly improvement in performance of PLT over the existing task assignment policies. 相似文献
10.
Functional biopolymers produced by biochemical technology considering applications in food engineering 总被引:5,自引:0,他引:5
Polysaccharides are widely used in foods as thickening, gelling, stabilizing, emulsifying, and water-binding agents. The majority
of the polysaccharides currently employed in the food industry are derived from plants and seaweeds. Recently, microbial polysaccharides
have emerged as an important set of biothickeners for foods. These biopolymers have overcome to great extent the flaws associated
with the plants and seaweeds polysaccharides. This relatively new class of biopolymers has unique rheological properties because
of their potential of forming very viscous solutions at low concentrations and pseudoplastic nature. This review deals with
the current applications of these microbial biopolymers in the food industry with a special focus on the commonly used important
exopolysaccharides in this area. 相似文献