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排序方式: 共有151条查询结果,搜索用时 15 毫秒
1.
This paper presents a new scheduling method for manufacturing system based on the Timed Petri Net model and a reactive fast graph search algorithm. The following two typical problems are addressed in this paper. (1) Minimization of the maximum completion time. (2) Minimization of the total tardiness. As for the problem (1), a new search algorithm which combines the RTA∗ and a rule-based supervisor is proposed. As for problem (2), the original Petri Net model is converted to its reverse model and the algorithm developed for the problem (1) is applied, regarding the due date as the starting time in the reverse model. Some numerical experiments are carried out to demonstrate usefulness of our algorithm. 相似文献
2.
In the present study, to remove methylene blue (MB) from aqueous solution, some agricultural residues and cheap bioadsorbents such as sawdust of palm trees, eucalyptus, and sour lemon were used. To do this, significant parameters like contact time, temperature, pH, initial concentration, and adsorbent dosage were checked. The results affirmed that the best conditions for MB adsorption from aqueous solution were obtained such as the temperature of 25?°C, pH of 8, adsorbent dosage of 2g/L, contact time of 120?minutes, and dye concentration of 5?mg/l which under these conditions the adsorption efficiencies determined were 95.8, 93.4, and 92.8% using sawdust of palm tree, eucalyptus, and sour lemon, respectively. Also, the equilibrium behavior of adsorbents showed that the Freundlich model could better predict the adsorption behavior of the process due to having a larger correlation coefficient (R2). The maximum biosorption capacities by Langmuir isotherm model were also obtained 54, 53.5, and 52.4?mg/g for sawdust of palm trees, eucalyptus, and lemon, respectively, which were significant amounts. In addition, kinetic behavior of adsorption showed that pseudo-second-order model can describe the kinetics of the adsorption process better than the pseudo-first-order model. Moreover, kinetic, equilibrium, and thermodynamic behaviors of adsorption affirmed that the biosorption process was desirable, physisorption, spontaneous, and exothermic. 相似文献
3.
针对传统的DEA模型在评估过程中并未考虑决策者对相关指标权重的偏好,将最优最差方法(BWM)嵌入到传统DEA模型中,基于决策者偏好排序的判断矩阵,构建一种含有偏好的DEA-BWM评价方法。首先在保持传统DEA方法的优势基础上,构建了CCR-BWM评价模型对各DMU进行评价。同时考虑为了便于各决策单元在统一权重基础上相互比较,构建了CSW-BWM公共权重模型。另外考虑决策单元自评和互评,构建了NCE-BWM中立型交叉效率。然后采用min-max方法分别将上述三种多目标评价模型转换为单目标线性规划进行求解。最后,选择一组算例对三种模型的有效性与合理性进行验证。 相似文献
4.
《Arabian Journal of Chemistry》2020,13(1):298-307
The present study is intended to adopt a facile method for preparing a sulphonated green carbon catalyst from date pits biomass. Catalyst synthesis involves in situ carbonization and sulphonation and it has been characterized by following techniques such as XRD, SEM, EDX, TEM, FTIR, TGA, and BET. Surface and internal morphology results exhibited that the synthesized sulphonated carbon material possesses a mesoporous structure, while activated carbon possesses a microporous structure. Furthermore, the Fourier transform infrared (FTIR) spectra confirmed the presence of acidic groups (OH, COOH, and SO3H) in synthesized sulphonated carbon material. Sulphonated carbon material exhibited high acidity (4.7 mmol/g) and good thermal stability. The application of this catalyst for the tertiary butylation of phenol without using any solvent has been investigated. The phenol alkylation reaction showed maximum conversion at reaction condition: temperature (140 °C) with 2 bar (nitrogen gas) pressure with maximum phenol conversion 79.27 wt%, with 68.01% selectivity towards 4TBP+2,4TBP, which is used as an intermediate in antioxidants. The catalyst exhibits comparable catalytic performance up to five reaction cycles. Thus it can be concluded that waste date pits can be successfully employed for green catalyst synthesis and used for reactions involving large molecules. 相似文献
5.
Natasha Flyer Zhen Qin Roger Temam 《Numerical Methods for Partial Differential Equations》2012,28(6):1996-2009
This article is the numerical counterpart of a theoretical work in progress Qin and Teman, Applicable Anal (2011), 1–19, related to the approximation of evolution hyperbolic equations with incompatible data. The Korteweg‐de Vries and Schrödinger equations with incompatible initial and boundary data are considered here. For hyperbolic equations, the lack of regularity (compatibility) is known to produce large numerical errors which propagate throughout the spatial domain, destroying convergence. In this article, we numerically test the effectiveness of the penalty‐based method proposed in Qin and Teman, Applicable Anal (2011), 1–19, which replaces the hyperbolic equations with incompatible data by a system with compatible data. We observe that convergence is increased. As explained in the text, in the case of the Schrödinger equation, the impact of incompatible (nonregular) data is most severe, and the authors are not aware of any other method that can handle such severe incompatible data. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2011 相似文献
6.
7.
SigmaPlot软件在化学实验数据处理中的应用 总被引:1,自引:0,他引:1
SigmaPlot是功能强大的数据分析和科学绘图软件,通过实例,初步介绍了SigmaPlot处理实验数据的方法和结果。结果表明,用SigmaPlot对实验数据作处理,解决了化学实验中数据多、处理麻烦、手工作图误差大等问题,使处理过程简单、快捷,提高了效率和准确性。 相似文献
8.
We study bicriteria problems of minimizing maximum tardiness and total due date assignment cost in various scheduling environments. We assume that each job can be assigned a different due date without any restriction, and that each due date assignment cost is a non-decreasing function of the quoted due date. We settle the complexity of most of the problems studied by either proving that they are NP-hard or finding a polynomial time solution for them. We also include approximation and non-approximability results for several parallel-machine problems. 相似文献
9.
10.
工件有到达时间的两机器自由作业稠密时间表 总被引:2,自引:0,他引:2
对于两机器自由作业加工总长问题,工件带有到达时间,我们证明了稠密时间表的性能比为1.5。 相似文献