Experimental Verification to Obtain Intrinsic Thermal Diffusivity by Laser-Flash Method

There is a need to obtain highly reliable values of thermophysical properties. The thermal conductivity of solids is often calculated from the thermal diffusivity, specific heat, and density, respectively, measured by the laser-flash method, differential scanning calorimetry, and Archimedes’ method. The laser-flash method is one of the most well-known methods for measuring the thermal diffusivity of solids above room temperature. This method is very convenient to measure the thermal diffusivity without contact in a short time. On the other hand, it is considered as an absolute reference measurement method, in particular, because only measurements of basic quantities such as time, temperature, length, and electrical quantities are required, and because the uncertainty of measurement can be analytically evaluated. However, it could be difficult in some cases to obtain reliable thermal-diffusivity values. The measurement results can indeed depend on experimental conditions; in particular, the pulse heating energy. A procedure to obtain the intrinsic thermal-diffusivity value was proposed by National Metrology Institute of Japan (NMIJ). Here, “intrinsic” means unique for the material, independent of measurement conditions. In this method, apparent thermal-diffusivity values are first measured by changing the pulse heating energy at the same test temperature. Then, the intrinsic thermal diffusivity is determined by extrapolating these apparent thermal diffusivities to a zero energy pulse. In order to verify and examine the applicability of the procedure for intrinsic thermal-diffusivity measurements, we have measured the thermal diffusivity of some materials (metals, ceramics) using the laser-flash method with this extrapolation procedure. NMIJ and Laboratoire National de Metrologie et d’essais (LNE) have laser-flash thermal-diffusivity measurement systems that are traceable to SI units. The thermal diffusivity measured by NMIJ and LNE on four materials shows good agreement, although they used different measurement systems and different analysis methods of the temperature-rise curve. Experimental verification on the procedure was carried out using the measured results. Some problems and considered solutions for laser-flash thermal-diffusivity measurements are discussed.     

A novel bi-level hierarchy towards available-to-promise in mixed-model assembly line sequencing problems

This article addresses advanced available-to-promise (AATP) in mixed-model assembly line sequencing problems. In the developed framework, customers are prioritized with respect to 11 defined criteria using the technique for order of preference by similarity to ideal solution (TOPSIS) method, and order quantities are calculated using a nonlinear mathematical program. Next, a mixed binary nonlinear mathematical program is developed to determine the optimum sequence of the optimized order quantities to minimize the total lateness. Since the proposed models are intractable, a hybrid genetic algorithm–simulated annealing method is also developed. Finally, an industrial case study is reported, the results of which validate the developed AATP framework.     

Synthesis of Lead(II) Minoxidil Coordination Polymer: A New Precursor for Lead(II) Oxide and Lead(II) Hydroxyl Bromide

A new lead(II) coordination polymer, [PbBr₂(C₉H₁₅N₅O)]_n (1), where C₉H₁₅N₅O is (2,4-diamino-6-piperidine-1-yl) pyrimidine N-oxide (minoxidil) is synthesized and characterized. Polymer 1 is synthesized in methanol by sonochemical and hydrothermal methods from lead(II) acetate, KBr and the minoxidil ligand. The crystal structure of [PbBr₂(C₉H₁₅N₅O)]_n indicates a syndiotactic coordination polymer. The Pb(II) atom lies on a mirror plane; the mirror plane is perpendicular to the pyrimidine ring bisecting the piperidine ring. N–H···O intramolecular and C–H···Br, N–H···N strong intermolecular interactions were observed. Micro-rods of PbO and nano-plates of PbOHBr were prepared by thermal decomposition of the nano-structured [PbBr₂(C₉H₁₅N₅O)]_n as a precursor. Characterization of the products was carried out using X-ray crystallography, elemental analysis, FTIR spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis and thermal analysis. The sonochemical method resulted in a significant reduction of reaction time, reaction temperature and particle sizes of the products.     

Application of Hyperspectral Technique for Color Classification Avocados Subjected to Different Treatments

In this study, the applicability of hyperspectral technique, a fast and non-destructive, novel method was investigated for the color discrimination of avocados subjected to different treatments. Fruits like avocados are coated with edible films to extend their shelf life. Using different formulations of coating with varying pectin, beeswax, and sorbitol contents, nine different coating preparations with potential to influence the ripening behavior of avocados were developed. Avocados were coated with these formulations, air-dried, and stored at room temperature. Concurrently, the reflectance responses of the avocado fruits were measured in 2,151 wavebands (350 to 2500 nm) with a field spectroradiometer. To tackle the co-linearity that exists between the spectral observations, aggregated 10- and 20-nm data sets were used. Using a stepwise procedure, the most effective wavebands capable of discriminating treatment effects were selected. By applying a discrimination procedure with a well-chosen subset of the selected wavebands, treatments were correctly classified with more than 92% accuracy.     

Elimination of mercury by adsorption onto activated carbon prepared from the biomass material

Following the previous work (Kaghazchi et al., 2010 [11]), dealing with applying a combination of two kinds of agricultural wastes to produce a new adsorbent, this study is dedicated to investigate the details of mercury adsorption process from aquatic medium by this adsorbent. So the Mix-ZC activated carbon (the sample prepared by chemical activation of a mixture of pistachio-nut shells and licorice residues impregnated with zinc chloride) was selected for doing a series of batch adsorption experiments on it. Equilibrium isotherms, such as Freundlich, Langmuir, Dubinin–Redushkevich and Temkin have been tested. Kinetic studies based on Lagergren first-order, pseudo-second-order rate expressions and intra-particle diffusion studies have been done. The mechanisms of mercury adsorption onto this adsorbent under the operating conditions were also studied.     

Synthesis of small-band gap poly(3,4-ethylenedioxythiophene methine)s using acidic ionic liquids as catalyst

Poly(3,4-ethylenedioxythiophene methine)s were synthesized in the presence of acidic ionic liquids for the first time. The polymers were obtained in good yields and viscosities ranging which were soluble in most common solvents such as NMP, THF, CH₂Cl₂, p-dioxane, chloroform, etc. The polymer structures were confirmed by FT-IR, UV–Vis-NIR, ¹H-NMR spectra, elemental and thermogravimetric analysis techniques. The thermal gravimetric analysis showed that the polymers had a fairly good thermal stability. The optical and electrochemical band gaps of the synthesized polymers were 1.16–2.3 and 1.7–2.05 eV, respectively. The electrochemical impedance spectroscopy studies were shown that polymers conductivity was greatly increased after doping of polymers with iodine.     

Cloud service selection using cloud service brokers: approaches and challenges

Cloud computing users are faced with a wide variety of services to choose from. Consequently, a number of cloud service brokers (CSBs) have emerged to help users in their service selection process. This paper reviews the recent approaches that have been introduced and used for cloud service brokerage and discusses their challenges accordingly. We propose a set of attributes for a CSB to be considered effective. DifFerent CSBs' approaches are classified as either single service or multiple service models. The CSBs are then assessed, analyzed, and compared with respect to the proposed set of attributes. Based on our studies, CSBs with multiple service models that support more of the proposed effective CSB attributes have wider application in cloud computing environments.