Approach by localization and multiobjective evolutionaryoptimization for flexible job-shop scheduling problems

Traditionally, assignment and scheduling decisions are made separately at different levels of the production management framework. The combining of such decisions presents additional complexity and new problems. We present two new approaches to solve jointly the assignment and job-shop scheduling problems (with total or partial flexibility). The first one is the approach by localization (AL). It makes it possible to solve the problem of resource allocation and build an ideal assignment model (assignments schemata). The second one is an evolutionary approach controlled by the assignment model (generated by the first approach). In such an approach, we apply advanced genetic manipulations in order to enhance the solution quality. We also explain some of the practical and theoretical considerations in the construction of a more robust encoding that will enable us to solve the flexible job-shop problem by applying the genetic algorithms (GAs). Two examples are presented to show the efficiency of the two suggested methodologies     

Optimisation of xanthan gum production by palm date (Phoenix dactylifera L.) juice by-products using response surface methodology

The present study was undertaken investigate and optimise the possibility of xanthan gum production by Xanthomonas campestris NRRL B-1459 in batch experiments on date palm juice by-products. Using an experimental Response Surface Methodology complemented with a Central Composite Orthogonal Design, three major independent variables (date juice carbon source, nitrogen source and temperature) were evaluated for their individual and interactive effects on biomass and xanthan gum production. The optimal conditions selected were: 84.68 g/l for carbon source, 2.7 g/l for nitrogen source, and 30.1 °C for temperature. The experimental value obtained for xanthan production under these conditions was about 43.35 g/l, which was close to the 42.96 g/l value predicted by the model. Higher yields of biomass production could be obtained at 46.68 g/l for carbon source, 4.58 g/l for nitrogen source and 30 °C for temperature. The maximum value obtained for biomass production was 3.35 g/l, which was higher than the 2.98 g/l value predicted by the model. The xanthan formed was subjected to HPLC and TLC analyses and its molecular weight as well as pyruvate content were identified. The findings indicated that this polysaccharide contained glucose, glucoronic acid and mannose. Overall, the date palm juice by-products presented in the current study seem to exhibit promising properties that can open new pathways for the production of efficient and cost-effective xanthan gum.     

Actinides oxalate precipitation in emulsion modeling: From the drop scale to the industrial process

An original process of actinides coprecipitation based on pulsed flow column is studied. The novelty of this process lies in the confinement of the aqueous reagents in separated droplets, dispersed in an inert organic phase (W/O emulsion). Precipitation occurs inside drops when they coalesce. Besides the implementation of well-known technologies of the nuclear industry, this precipitation in emulsion process is particularly convenient for the control of supersaturation, and ensures the sticky precipitates’ confinement within drops, thereby limiting the fouling risk and its adverse consequences on productivity and safety.     

A Finite Volume Framework for Geometric Surface Processing

We present a surface denoising method using the vertex-centered finite volume method coupled with the mesh covariance fractional anisotropy. The approach is computationally fast and able to effectively remove undesirable noise while preserving prominent geometric features of a 3D mesh surface such as curved surface regions, sharp edges, and fine details. Extensive experimental results on various 3D models demonstrate the effectiveness of the proposed iterative algorithm, which yields satisfactory output results in just one single iteration.     

Approximation algorithm for the weighted flow-time minimization on a single machine with a fixed non-availability interval

In this article, we consider the non-resumable case of the single machine scheduling problem with a fixed non-availability interval. We aim to minimize the weighted sum of completion times. No polynomial 2-approximation algorithm for this problem has been previously known. We propose a 2-approximation algorithm with O(n²) time complexity where n is the number of jobs. We show that this bound is tight. The obtained result outperforms all the previous polynomial approximation algorithms for this problem.     

一种改进的Ribbon snake遥感图像道路网自动生成算法

针对树木或高大建筑物遮挡以及噪声等因素造成道路提取结果不完整的现象,根据道路的几何特征,在Snake模型中加入道路宽度信息,构造Ribbon Snake模型。为了克服模型对内部参数依赖性较大、容易受到复杂背景干扰影响的不足,采用B样条曲线对道路的平滑性进行约束,与Ribbon Snake相结合建立道路提取算法,通过调节控制点的数目增强曲线的灵活性。从改进的B样条Ribbon Snake的道路网分割结果可以看出,分割的结果更加平滑,精度更高,对噪声具有更好的鲁棒性。