A Hybrid Meta-Heuristic for the Batching Problem in Just-In-Time Flow Shops

This paper is concerned with a batching problem encountered in the context of production smoothing in just-in-time manufacturing systems. The manufacturing system of interest is a multi-level system with a flow-shop at the final level. We develop a hybrid meta-heuristic method to solve the batching problem, which is known to be NP-hard. We hybridize strategic oscillation (SO) and path re-linking (PR) methods and compare the hybrid method's performance to two benchmark methods: a bounded dynamic programming method developed for the problem earlier and an implementation of robust tabu search (RTS) meta-heuristic. Through a computational study, we show that the proposed hybrid method is effective in solving the problem within several minutes of computer time and yielding near-optimal results.     

Photosensitivity and grating development in trans-4-stilbenemethanol-doped poly(methyl methacrylate) materials

This paper reports the photosensitivity of poly(methyl methacrylate) (PMMA) and its copolymer doped with trans-4-stilbenemethanol. UV irradiation of the doped-PMMA at 325 nm induced the trans- to cis-isomerization of the dopant. This process was confirmed by ¹H NMR spectra of trans-4-stilbenemethanol in CDCL₃ solvent before and after irradiation. The isomerization can be initiated by the irradiation with an intensity of 0.62 mW/cm². Photo-induced refractive index change of −0.0024 was obtained when a PMMA copolymer film doped with 5.1 wt% dopant was exposed to 325 nm light. Lorentz-Lorenz equation was used to estimate the refractive index of a trans-4-stilbenemethanol-PMMA composite and a trans-4-stilbenemethanol-PMMA copolymer composite from the mole refraction and van der Waals volume of each component. A slight elevation of molecular packing coefficient (K) for PMMA and its copolymer containing the dopant implies a denser aggregation as compared to the polymer without the dopant. Long period gratings were created in doped-PMMA films and doped-PMMA copolymer fibers using amplitude mask technique. Gratings were confirmed by microscopic observation and diffraction patterns.     

A TSP (1,2) application arising in cable assembly shops

One of the main operations in producing cable systems in the automotive industry is that of cutting/stripping/crimping. The most time-consuming activity in this operation is changing the heads whenever a different connector is to be crimped at either one of the ends. This set-up time is practically doubled when the heads at both ends are to be changed. Thus, one is faced with the problem of minimizing the total machine set-up time; which turns out to be a TSP where the distances between the nodes are either one or two. A simple and effective heuristic algorithm is developed that yields solutions, which are only a few percent above the optimum in the worst case.     

Light scattering by DNA structure due to phase transition

Modelling and numerical calculations of light scattering by the deoxyribonucleic acid (DNA) molecule were investigated using the transition matrix method at the phase transition region. In this model for a DNA molecule with helix structure, the electrical field was established and the transition matrix calculated for this field. Numerical computation of a simple cylindrical model, represented by adenine–thymine (A–T) and guanine–cytosine (G–C) formed with a lamellar-like helix, enabled important results to be obtained. These results were generalized for different molecular orientations with dielectric properties at the phase transition, which occurred due to the electric field changing. Finally, these results are associated with improved models for previous geometries.     

The formation of a metallosupramolecular porous helicate through salicylaldehydethiosemicarbazone: Synthesis,Characterization, Cytotoxic activity,DNA binding and DFT calculations

The reaction of salicylaldehyde‐S‐methylisothiosemicarbazone in the presence of ethylenediamine base and iron (III)chloride generated unforeseen homotopic dinuclear triple‐stranded iron (III)helicate. The synthesized helicate was characterized by elemental analysis, IR, UV–Vis spectroscopy, magnetic moment measurement, and evaluated cytotoxic activities against K562, HL‐60 and THP‐1 leukemia cells. In addition, solid‐state structure has been determined by single‐crystal X‐ray diffraction technique. In the complex, three dinucleating O, N, N, O donor ligands provide three diazine (═N─N═) bridges between the metal ions and facial O₃N₃ coordination spheres around them. The ligands are folded about the N ─ N single bond and coordinated to the two metal ions in a helical fashion to form the triple helical structure. In the crystal lattice, chains of centrosymmetric rings, which are connected to one another via π─π stacking interactions, are generated by C─H···O intermolecular interactions. The results are also confirmed by the density functional theory (DFT) calculations. The results obtained from the cytotoxicity test showed to be effective in low concentrations on the leukemia cells. An intercalative binding mode of helicate‐DNA complex was confirmed with the high intrinsic binding constant (K_b = 8×10⁶ M^?1) and competitive displacement assay of Ethidium bromide with high Ksv value.     

Preconcentration of Nickel and Cobalt Prior to Their Determination by Graphite Furnace Atomic Absorption Spectrometry Using the Water-Soluble Polymer Poly(Vinyl Pyrrolidinone)

The use of a water-soluble polymer, poly(vinyl pyrrolidinone) (PVP), for the preconcentration and separation of nickel and cobalt prior to their determination by graphite furnace atomic absorption spectrometry is described. For this purpose, the sample and the water-soluble polymer solutions were mixed, and the metal-bound polymer was precipitated by pouring the mixture into acetone. The precipitate was separated by decantation and dissolved with distilled-deionized water. The analyte elements were determined by graphite furnace atomic absorption spectrometry. The validity of the method was tested with spiked sea water and mineral water samples. The analytes added to the samples were quantitatively recovered within the range of 95% confidence limits. The proposed technique is fast, simple, precise and inexpensive. Its low blank values and high precision are other important advantages.     

On the theory of radiation of an infinitely long charged current-carrying thread in a uniaxial transparent crystal

The problem relating to the synchrotron radiation of a charged current-carrying thread in a uniaxial transparent crystal is considered here using the Sitenko-Kolomensky method. The formulas for the intensity of the synchrotron radiation and the limiting values of the formulas giving the intensity of the Cerenkov radiation of a thread moving uniformly and rectilinearly parallel to the optical axis of a crystal have been derived.     

Existence and uniqueness for a nonlinear inverse reaction‐diffusion problem with a nonlinear source in higher dimensions

This paper analyzes the existence and the uniqueness problem for an n‐dimensional nonlinear inverse reaction‐diffusion problem with a nonlinear source. A transformation is used to obtain a new inverse coefficient problem. Then, a parabolic differential operator L_λ is defined to establish the relation between the solution of L_λ = 0 and the new inverse problem. Following this, it is shown that the inverse problem has at least one solution in the class of admissible coefficients. Furthermore, it is proved that this solution is the unique solution of the undertaken inverse problem. A numerical example is given to illustrate ill‐posedness of the inverse problem. Copyright © 2013 John Wiley & Sons, Ltd.     

FAAS slurry analysis of lead and copper ions preconcentrated on titanium dioxide nanoparticles coated with a silver shell and modified with cysteamine

We report on the separation and preconcentration of lead(II) and copper(II) ions using silver-coated titanium dioxide nanoparticles modified with cysteamine, and their determination by slurry analysis via flame atomic absorption spectrometry. The ions were adsorbed via a conventional batch technique, and the ion-loaded slurry was separated and directly introduced into the spectrometer, thereby eliminating a number of drawbacks. The effects of pH, amount of sorbent, slurry volume, sample volume and other ions on the recovery were investigated. Under optimized experimental conditions, copper and lead can be recovered within the 95% confidence level in certificated waste water, but also in spiked sea water samples. The technique is fast, simple, and leads to complete elution. The limit of detection (3δ, at n?=?10) was 0.37 μg L^?1 for Cu(II), and 0.38 μg L^?1 for Pb(II).