排序方式: 共有26条查询结果,搜索用时 390 毫秒
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
下载免费PDF全文
![点击此处可从《Journal of food science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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.
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
5.
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
6.
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
7.
8.
9.
Taous Aissani Idris Yahiaoui Farouk Boudrahem Sabrina Ait Chikh Farida Aissani-Benissad Abdeltif Amrane 《分离科学与技术》2018,53(9):1423-1433
The major factors affecting the removal efficiency of sulfamethazine (SMT) by photocatalysis process in the presence of TiO2 P25 or ZnO, namely the pH, the amount of catalyst and the initial SMT concentration were examined. The obtained results showed the absence of adsorption of SMT on the catalysts and the absence of degradation of SMT by direct photolysis under UV light in the absence of catalyst. The variation of the pH solution in the range 4–9 did not cause any significant degradation of SMT. The optimal amounts of each catalyst were, respectively, 0.5 and 0.25 g/L for TiO2 P25 and ZnO. Increasing the initial SMT concentration impacted negatively the removal efficiency, which decreased from 31% to 13% and from 100% to 27% in the presence of TiO2 P25 and ZnO in the presence of 10 mg/L and 50 of SMT after 30-min reaction time, respectively. The obtained results showed better efficiency of ZnO than TiO2 P25 regarding both removal efficiency and chemical oxygen demand (COD) abatement. However, removal efficiency and COD abatement were not complete, even after 7 h of photocatalysis, about 92% and 41%, respectively. The biodegradability was examined after photocatalysis performed in the following conditions: [SMT]0 = 50 mg/L, pH = 6, T = 25°C, ω = 360 rpm and 0.5 g/L of TiO2 P25 or 0.25 g/L of ZnO. In these conditions, the removal efficiencies were, respectively, 26% and 41% in the presence of TiO2 P25 and 55 and 92% in the presence of ZnO after 4 and 7 h of pretreatment times, respectively. The BOD5/COD ratio increased substantially and, respectively, from 0 to 0.25 and from 0 to 0.16 in the presence of TiO2 P25 and ZnO after 7 h of irradiation. Even if the limit of biodegradability (0.4) was not achieved, a subsequent biological treatment was considered in the presence of TiO2 P25, leading to 58% COD abatement after a 28-day culture. 相似文献
10.
This work deals with cementation of silver onto iron grid in fixed bed reactor. The influence of several parameters is studied namely: initial concentration of silver [Ag+]0, flow rate, solution pH, and mass of iron. Moreover, their influence on the yield of the reaction of cementation is investigated statistically by the experimental design in view of industrial application. The estimation and the comparison of the parameter's effects are realised by using two‐level factorial design. The analysis of these effects permits to state that the most influential factor is the mass of iron with an effect of (+5.642), the second in the order is the initial concentration of silver ions (Ag+) with an effect of (+4.005), the third is the flow rate of the electrolytic solution with an effect of (+3.824). A central composite design methodology is employed to determine the optimum conditions for a silver cementation yield onto iron grid. For this end, the experimental results were approximated by a second‐order model as well as the surface contour plots and surface responses are drowned. The optimal conditions found for initial silver concentration, such as a flow rate, pH of the solution and mass of iron, are respectively: 21.25 mg/L, 4.43 L/min, 3.6 and 50 g. Under these conditions, the obtained silver cementation yield is 96.851%. 相似文献