Processing map for hot working of spray formed and hot isostatically pressed Al–Li alloy (UL40)

The hot deformation behavior of spray formed + HIPed Al–Li (UL40) alloy was studied using processing map technique. The map has been interpreted in terms of the microstructural processes occurring in situ with deformation, based on the values of a dimensionless parameter η which is an efficiency index of energy dissipation through microstructural processes. An instability criterion has also been applied to demarcate the flow instability regions in the processing map using another parameter (ξ). Both the parameters (η and ξ) were computed from the experimental data generated by compression tests conducted at various temperature and strain rate combinations over the hot working range (375–575 °C and 3 × 10⁻⁴ to 1 s⁻¹) of the present material. The processing map exhibits three distinct η domains without any unstable flow conditions under the investigated temperature and strain rate conditions. The dominant microstructural mechanisms corresponding to these domains were identified to be extended dynamic recovery, grain boundary cavitation and flow localization. The stress–strain, microstructure and hot ductility recorded under the deformation conditions of these domains were correlated to the microstructural processes. The ‘safe window’ for hot working of HIPed UL40 material has been identified based on these results. Further, the significance of HIPing on the hot workability has been enunciated by comparing the results of the present material with the as-spray formed material.     

Investigations of the optical absorption spectra of porous silicon layers on the Silicon backing by the nondestructive photoacoustic method

This paper presents a series of experimental photoacoustic spectra of porous silicon layers on the crystalline silicon and their numerical analysis performed in the proposed two layer model. The goal of the analysis was to calculate the optical absorption coefficient spectra of porous silicon from the photoacoustic spectra of the porous silicon layer on the silicon backing. The character of the observed optical absorption band associated with the porous silicon was revealed.     

MATLAB用于激光光束质量分析

介绍了利用CCD、计算机并基于MATLAB开发的激光光束质量分析的软件,详细地介绍了该软件的组成、实现的基本功能及其特点。     

Creation and control of high-dimensional multi-partite classically entangled light

Vector beams, non-separable in spatial mode and polarisation, have emerged as enabling tools in many diverse applications, from communication to imaging. This a...     

An Efficient Implementation and Analysis of Tail-Biting Convolution Coding Algorithm for OFDM Based System in Terms of Speed,Memory and Peak-to-Average Power Ratio Using DSP

Wireless Personal Communications - Fourth Generation (4G) mobile communication system uses Orthogonal Frequency Division Multiplexing (OFDM). With this technique, high data rate demands are...     

Genotyping by Sequencing Reveals Genetic Relatedness of Southwestern U.S. Blue Maize Landraces

Maize has played a key role in the sustenance and cultural traditions of the inhabitants of the southwestern USA for many centuries. Blue maize is an important component of the diverse landraces still cultivated in the region but the degree to which they are related is unknown. This research was designed to ascertain the genotypic, morphological, and phenotypic diversity of six representative southwestern blue maize landraces. Their genotypic diversity was examined using tunable genotyping-by-sequencing (tGBS™). A total of 81,038 high quality SNPs were identified and obtained through tGBS. A total of 45 morphological and biochemical traits were evaluated at two locations in New Mexico. The varieties Los Lunas High and Flor del Rio were genetically less related with other southwestern landraces whereas diffusion between Navajo Blue, Hopi Blue, Yoeme Blue, and Taos Blue demonstrated that these landraces were genetically related. Phenotypic variability was highest for kernel traits and least for plant traits. Plant, ear, and kernel traits were fairly consistent within and across locations. Principal component analysis and tGBS showed that Corn Belt variety ‘Ohio Blue’ was distinctly different from southwestern landraces. Genotypic analysis displayed that southwestern landraces are genetically closely related, but selection has resulted in differing phenotypes. This study has provided additional insight into the genetic relatedness of southwestern blue maize landraces.     

Identifying the Activity Origin of a Cobalt Single-Atom Catalyst for Hydrogen Evolution Using Supervised Learning

Single-atom catalysts (SACs) have become the forefront of energy conversion studies, but unfortunately, the origin of their activity and the interpretation of the synchrotron spectrograms of these materials remain ambiguous. Here, systematic density functional theory computations reveal that the edge sites—zigzag and armchair—are responsible for the activity of the graphene-based Co (cobalt) SACs toward hydrogen evolution reaction (HER). Then, edge-rich (E)-Co single atoms (SAs) were rationally synthesized guided by theoretical results. Supervised learning techniques are applied to interpret the measured synchrotron spectrum of E-Co SAs. The obtained local environments of Co SAs, 65.49% of Co-4N-plane, 13.64% in Co-2N-armchair, and 20.86% in Co-2N-zigzag, are consistent with Athena fitting. Remarkably, E-Co SAs show even better HER electrocatalytic performance than commercial Pt/C at high current density. Using the joint effort of theoretical modeling, thorough characterization of the catalysts aided by supervised learning, and catalytic performance evaluations, this study not only uncovers the activity origin of Co SACs for HER but also lays the cornerstone for the rational design and structural analysis of nanocatalysts.     

Photocatalytic activity of metal nanoparticle-decorated titanium dioxide for simultaneous H2 production and biodiesel wastewater remediation

A set of metal nanoparticle-decorated titanium dioxide(M_x/TiO_2; where x is the percent by mass, %)photocatalysts was prepared via the sol-immobilization in order to enhance the simultaneous hydrogen(H_2)production and pollutant reduction from real biodiesel wastewater. Effect of the metal nanoparticle(NP) type(M = Ni, Au, Pt or Pd) and, for Pd, the amount(1 %–4 %) decorated on the surface of thermal treated commercial TiO_2(T_(400)) was evaluated. The obtained results demonstrated that both the type and amount of decorated metal NPs did not significantly affect the pollutant reduction, measured in terms of the reduction of chemical oxygen demand(COD), biological oxygen demand(BOD) and oil grease levels, but they affected the H_2 production rate from both deionized water and biodiesel wastewater, which can be ranked in the order of Pt_1/T_(400) Pd_1/T_(400) Au_1/T_(400) Ni_1/T_(400). This was attributed to the high difference in work function between Pt and the parent T_(400). However, the difference between Pt_1/T_(400) and Pd_1/T_(400) was not great and so from an economic consideration, Pd/TiO_2 was selected as appropriate for further evaluation. Among the four different Pd x/TiO_2 photocatalysts, the Pd_3/TiO_2 demonstrated the highest activity and gave a high rate of H_2 production(up to135 mmol·h_(-1)) with a COD, BOD and oil grease reduction of 30.3%, 73.7% and 58.0%, respectively.