Multilayer structure of tantalum anodic oxide films formed in dilute phosphoric acid

An investigation has been made of the multilayer structure of anodic oxide films on pure tantalum, formed up to various voltages with a constant current density of 1.0 mA cm^-2 in 1.0 × 10^-2 N H₃PO₄ at 20°C. For the study, infrared reflectance spectra (IRRS) were recorded and the optical thickness measuring method was successfully applied using the wavelengths of optical interference maxima and a chemical film stripper (concentrated ammonium hydrogen difluoride aqueous solution).The conclusions are that: (1) tantalum anodic oxide films anodized in dilute phosphoric acid consist of three layers, irrespective of the formation voltage; (2) the innermost layer is uniform whatever the anodization voltage; (3) phosphate anions are incorporated in both the outermost and middle layers but not in the innermost layer; (4) all three layers grow from the initial formation stage and the growth rates are nearly equal; (5) for formation voltages below 100 V the middle layer has an unchanging chemical structure, but above 100 V its chemical structure changes with the voltage; (6) the outermost layer appears to vary in chemical structure over all anodization voltages.     

Turbulent fluid flow phenomena in metals processing operations: Mathematical description of the fluid flow field in a bath caused by an impinging gas jet

A mathematical representation is developed for describing the flow field in liquids or melts, agitated by a symmetrically placed impinging gas jet. The problem is formulated by the statement of the axi-symmetrical turbulent fluid flow equations using the Prandtl-Komogorov model for the eddy viscosity. The resultant differential equations are solved numerically and the computed results are shown to be in reasonable agreement with experimental data reported in the literature. This problem is thought to be relevant to various metals refining operations and the results should also be helpful for the interpretation of laboratory scale studies in which molten metals are contacted with impinging gas jets.     

A new approach for solving singular systems in topology optimization using Krylov subspace methods

In topology optimization, elements without any contribution to the improvement of the objective function vanish by decrease of density of the design parameter. This easily causes a singular stiffness matrix. To avoid the numerical breakdown caused by this singularity, conventional optimization techniques employ additional procedures. These additional procedures, however, raise some problems. On the other hand, convergence of Krylov subspace methods for singular systems have been studied recently. Through subsequent studies, it has been revealed that the conjugate gradient method (CGM) does not converge to the local optimal solution in some singular systems but in those satisfying certain condition, while the conjugate residual method (CRM) yields converged solutions in any singular systems. In this article, we show that a local optimal solution for topology optimization is obtained by using the CRM and the CGM as a solver of the equilibrium equation in the structural analysis, even if the stiffness matrix becomes singular. Moreover, we prove that the CGM, without any additional procedures, realizes convergence to a local optimal solution in that case. Computer simulation shows that the CGM gives almost the same solutions obtained by the CRM in the case of the two-bar truss problem.     

Characterization of the vibrational damping loss factor and viscoelastic properties of ethylene–propylene rubbers reinforced with micro‐scale fillers

The influence of microscale fillers on ethylene–propylene rubbers (EPR) was examined with respect to their vibrational damping capacity and viscoelastic properties. The vibrational damping and dynamic mechanical properties of reinforced EPR were studied in systematic and comparative ways that reinforced the evidence of a direct relation between the vibrational damping loss factor and its mechanical damping loss factor. In this study, the sensitivity of the vibrational damping loss factor of reinforced EPR was quantified with respect to the variation in thickness, filler type, and filler content. Dynamic mechanical relaxation behaviors were also analyzed. The viscoelastic properties in terms of the storage modulus, loss modulus, mechanical damping loss factor, and frequency dependence of molecular relaxation showed interesting results with the filler types and compositions that had good correspondence with the vibrational damping behaviors. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3058–3066, 2001     

A matched filter approximation for SC/MMSE iterative equalizers

This letter proposes a new iterative ISI equalization algorithm that offers low computational complexity: order L² with channel memory length L. The proposed algorithm is an extension of Reynolds and Wang's SC/MMSE (soft canceler followed by MMSE filter) equalizer: approximations are used properly to reduce the computational complexity. It is shown that the approximations used in the proposed algorithm do not cause any serious performance degradations from the trellis-based iterative equalization algorithms     

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by Pd complex with diimine ligands

Pd complexes with diimine ligands were investigated as novel Pd catalysts for direct synthesis of diphenyl carbonate by oxidative carbonylation of phenol using carbon monoxide and air. Best efficiency was obtained by using a PdCl₂(ArN=CH–)₂ or PdCl₂(ArN=CMe–)₂/Mn(TMHD)₃/(Ph₃P=)₂NBr system where TOF reached 8.08 and 8.00 mol-DPC/mol-Pd h, respectively. The efficiency was increased with increases in the CO pressure.     

蜘蛛丝研究与应用概述

尽管研究人员欣赏蜘蛛丝经过4亿年进化而形成的卓越性能，但以蜘蛛的速度纺蜘蛛丝还未实现商业化运作。一些科学小组正在寻找提高纺丝速度的途径，包括快速去除蛋白液中水分和迫使蛋白分子更快排列的技术。科学家们还希望通过同时纺几百根丝来加工复丝。研究人员和生物学家们正在利用毛虫、酵母、细菌、母牛和仓鼠、苜蓿草和山羊等的转基因技术来进行各种蜘蛛丝品种的试验，最终目的是开发出模仿或超越天然丝所有性能的蜘蛛丝。这些丝将拥有更广泛的应用领域，从医用缝合线到防弹背心。     

Superconducting Magnetic Filter: Performance, Recovery, and Design

Due to the development of superconducting magnets, the magnetic filtration process is now undergoing its biggest evolution since its conception. In Japan, the first industrial superconducting magnetic filter has been successfully applied for factory wastewater treatment. Much effort in both theory and practice is needed to further contribute to the new developments of this high gradient magnetic filtration process. In this substantial review, we have collected the most important theoretical and practical data about magnetic filtration, its recovery and design to establish a good framework for further development of this amazing technology.