Ant colony systems for the single-machine total weighted earliness tardiness scheduling problem

Single-machine weighted earliness tardiness scheduling is a prevalent problem in just-in-time production environments. Yet, the case with distinct due dates is strongly NP-hard. Herein, it is approximately solved using ASV, an ant colony-based system with a reduced number of ants and of colonies and with daemon actions that explore the search space around the ants using a variable neighborhood search (VNS). The numerical investigation provides computational proof of the utility of the daemon actions. In addition, it infers that these latter can be applied either to the initial or to subsequent colonies. Furthermore, it highlights the importance of using ant colony optimization as the multiple restart engine of VNS. Finally, it shows that ASV obtains the optimum for most small-sized instances. It has a 0.2 % average deviation from the optimum over all benchmark instances.     

Minimising total weighted earliness and tardiness on parallel machines using a hybrid heuristic

Scheduling jobs with different processing times and distinct known due dates on parallel machines (which may be idle) so as to minimise the total weighted earliness and tardiness is NP-hard. It occurs frequently in industrial settings with a just-in-time production environment. Here, small instances of this problem are tackled via an exact mixed-integer program, whereas larger instances are approximately solved using hybrid algorithms. The computational investigation discerns what makes a difficult instance, and demonstrates the efficiency of the approach.     

Effect of elaboration parameters of a membrane ceramic on the filtration process efficacy

The formation of the flat membrane from kaolin and potassium phosphate was investigated with a particular focus on the appropriate elaboration parameters and the effect of their separation performance. The first step consisted in the fabrication of flat ceramic membrane supports from mechanochemicaly-treated kaolin (K) and starch (S). The mechanical properties, permeability and porosity of these supports were studied as a function of the milling time of kaolin, the starch content, the sintering temperature and time. The optimization of the elaboration parameters led to the fabrication of supports from kaolin milled for 30 min and 5% starch at sintering temperature of 1100 °C and sintering time of 1 h. In the second step, the potassium phosphate was added as a binder in the kaolin- 5% starch mixture. In this case, we noted the improvement of the permeability without reduction of the mechanical strength and porosity. Also, the separation performances and the fouling of membranes elaborated with different potassium phosphates were evaluated using Bovine Serum Albumin (BSA) solution.     

Automatic layout of statecharts

Graphical notations are widely used for system specification. The usefulness of these notations depends primarily on their readability. Hence, automatic methods are needed to obtain efficient and understandable graphical representations of requirements. In this paper, we present an algorithm that automatically generates layouts of statecharts. We assume that relevant information is stored in a structure that we call a decomposition tree, and we draw the graph that models a statechart in a hierarchical fashion. Our approach excludes diagrams with inter‐level transitions. Copyright © 2001 John Wiley & Sons, Ltd.     

Effect of E-Glass fibre and ply orientation on the mechanical behaviour of FRP composites used for pressure pipe

The main goals of this experimental investigation were to compare the mechanical behaviour of resins reinforced with different woven fabrics (bidirectional and quadriaxial rovings), manufactured with the classical hand lay-up process, and to find the more appropriate industrial pressure pipe. In order to realize such applications, several mechanical properties need to be evaluated. So, a focus was essentially done on the evaluation of the effect of resin and E-Glass fibre ply orientation on the mechanical properties such as tensile strength and flexural strength of the studied composite laminates. An experimental failure analysis was carried out to observe the crack paths and failure mechanisms in the investigated laminate composites. From the main results, it was found that the composites based on R500 fabrics show the best behaviour in tensile while the laminates based on RM fabrics present the best flexural properties. The quadriaxial composite laminates (QA/VE and QA/UP) with stacking sequences of [0°, +45°, 90°, ?45°] present a very ductile tensile behaviour and the highest interlaminar fracture resistance. Consequently, they can be more appropriate for the industrial pressure pipe.     

Faceting mechanisms of Si nanowires and gold spreading

We report detailed structural analysis of 〈111〉 oriented silicon nanowires (NWs) grown by UHV–CVD using the VLS process with a gold catalyst. STEM-HAADF observations have revealed an unexpected inhomogeneous distribution of gold nanoclusters on the NW surface. Gold is mainly distributed on three sides among the six {112}-sidewalls and is anchored on upward {111} facets. This original observation brought us a new comprehension of the faceting mechanisms. The stability of the 〈111〉 growth direction needs the formation of facets on {112}-sidewalls with energetically favorable planes. We demonstrate that the initial formation of covered facets with a three-fold symmetry is driven by the formation of {111} Au/Si interfaces between the nucleated Si NW and the Au droplet.     

Manufacturing and mechanical characterization of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/β-TCP/TiO<Subscript>2</Subscript> biocomposite as a potential bone substitute

This paper focuses on the mechanical characterization of a bioceramic based on commercial alumina (Al₂O₃) mixed with synthesized tricalcium phosphate (β-TCP) and commercial titania powder (TiO₂). The effect of β-TCP and TiO₂ addition on the mechanical performance was investigated. After a sintering process at 1600 °C for 1 h, various mechanical properties of the samples have been studied, such as compressive strength, flexural strength, tensile strength, elastic modulus, and fracture toughness. The measurements of the elastic modulus (E) and the tensile strength (σ _t ) were conducted using the modified Brazilian test while the compressive strength (σ _c ) was determined through a compression test. Also, semi-circular bending (SCB) specimens were used to evaluate the flexural strength (σ _f ) and the opening mode fracture toughness (K _IC). From the main results, it was found that the best mechanical performance is obtained with the addition of 10 wt.% TCP and 5 wt.% TiO₂. Alumina/10 wt.% tricalcium phosphate/5 wt.% titania composites displayed the highest values of mechanical properties and a good combination of compressive strength (σ _c ?≈?352 MPa), flexural strength (σ _f ?≈?98 MPa), tensile strength (σ _t ?≈?86.65 MPa), and fracture toughness (K _IC?≈?13 MPa m^1/2).     

Salt effects on Origanum majorana fatty acid and essential oil composition

BACKGROUND: The effects of salt on the essential oil yield and fatty acid composition of aerial parts of two marjoram varieties were investigated. Plants with 6 leaves were treated with NaCl (75mM). RESULTS: Salt treatment led to a reduction in aerial part growth. Salinity increased the fatty acid content more significantly in Tunisian variety (TV) than in Canadian variety (CV). CV showed an increase in double‐bond index (DBI) and a decrease in malondialdehyde content under salt stress, while the opposite was observed in TV. The DBI was mainly affected by a strong reduction in oleic and linoleic acids in TV, whereas a strong stimulation of linoleic acid in CV was observed. Salt decreased and increased the essential oil yield in TV and CV respectively. The main constituents of the essential oil of TV were trans‐hydrate sabinene and terpinen‐4‐ol, which showed a significant decrease under salt stress. In contrast, the main constituents of the essential oil of CV were sabinene and trans‐hydrate sabinene, which showed a significant decrease and increase respectively under salt stress. CONCLUSION: Marjoram oil is a rich source of many compounds such as essential oils and fatty acids, but the distribution of these compounds differed significantly between the two varieties studied. Copyright © 2011 Society of Chemical Industry     

Microdevice for Separation of Circulating Tumor Cells Using Embedded Magnetophoresis with V‐shaped Ni‐Co Nanowires and Immuno‐nanomagnetic Beads

The novelty of this study resides in a 6”‐wafer‐level microfabrication protocol for a microdevice with a fluidic control system for the separation of circulating tumor cells (CTCs) from human whole blood cells. The microdevice utilizes a lateral magnetophoresis method based on immunomagnetic nanobeads with anti‐epithelial cell adhesive molecule antibodies that selectively bind to epithelial cancer cells. The device consists of a top polydimethylsiloxane substrate for microfluidic control and a bottom substrate for lateral magnetophoretic force generation with embedded v‐shaped soft magnetic microwires. The microdevice can isolate about 93% of the spiked cancer cells (MCF‐7, a breast cancer cell line) at a flow rate of 40/100 mL/min with respect to a whole human blood/buffer solution. For all isolation, it takes only 10 min to process 400 mL of whole human blood. The fabrication method is sufficiently simple and easy, allowing the microdevice to be a mass‐producible clinical tool for cancer diagnosis, prognosis, and personalized medicine.