An optical channel modeling of a single mode fiber

The evaluation of the optical channel model that accurately describes the single mode fibre as a coherent transmission medium is reviewed through analytical, numerical and experimental analysis. We used the numerical modelling of the optical transmission medium and experimental measurements to determine the polarization drift as a function of time for a fixed length of fibre. The probability distribution of the birefringence vector was derived, which is associated to the ‘Poole’ equation. The theory and experimental evidence that has been disclosed in the literature in the context of polarization mode dispersion – Stokes & Jones formulations and solutions for key statistics by integration of stochastic differential equations has been investigated. Besides in-depth definition of the single-mode fibre-optic channel, the modelling which concerns an ensemble of fibres each with a different instance of environmental perturbation has been analysed.     

The Effects of Heat Treatment on the Corrosion Behavior of HVOF-sprayed WC-17 wt % Co Coatings

Protection of Metals and Physical Chemistry of Surfaces - A WC-17 wt % Co coating was deposited onto a ST37 mild steel substrate by HVOF-spray technique and then vacuum heat treated at 1100°C....     

Thermal and electrical stability of TaN x diffusion barriers for Cu metallization

Amorphous TaN _x thin films (14 and 62 nm) were deposited by reactive sputtering on Si substrates. Crystallization and the metallurgical failure mechanism for Si/TaN _x /Cu metallization stacks were investigated by resistivity measurements, X-ray diffraction analysis, detailed electron microscopy and elemental depth profiling on samples annealed in 5 %H₂/95 %N₂ gas for 30 min at various temperatures ranging from 300 to 900 °C. Amorphous TaN _x thin films crystallized at 600 °C to hexagonal Ta₂N by a polymorphous transformation. Depending on film thickness, polycrystalline Ta₂N diffusion barriers were effective up to 700–800 °C. Failure occurred by diffusion of Cu to the Si/TaN _x interface to form Cu₃Si particles followed by outdiffusion of Si and formation of Cu₃Si and TaSi₂ precipitates on the outer surface. The TaN _x barriers were integrated in metal–oxide–semiconductor devices (Cu/10 nm TaN _x /26 nm SiO₂/Si) to evaluate their electrical failure after bias-temperature-stress (BTS) testing using capacitance–voltage and current–voltage measurements. The shift in flat-band voltage and the leakage current were monitored before and after BTS. The electrical test results were compared with compositional and morphological information obtained from elemental depth profiling and electron microscopy. No evidence of Cu diffusion to SiO₂ was found for capacitors with large leakage currents.     

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.