The Bonding Mechanism and Experimental Verification of Pilger Hot Rolling Clad Tube

In this paper, we focus on the bonding mechanism of bimetallic clad tube because of its low cost and comprehensive properties. The numerical simulation and the experiment are carried out from the diffusion behavior of carbon atoms in the metallurgical bonding process. Based on the dislocation density model of Kocks, the tube billets are rolled by pilger hot rolling; the outer tube is 06Cr19Ni10 stainless steel, the inner tube is Q235 carbon steel, and the wall thickness ratio is 1 : 1. The research shows that the diffusion ability of carbon atoms mainly depends on the degree of the plastic strain in the stainless steel hot rolling process; there is positive correlation between the thickness of bonding carburized layer and the dislocation density produced by plastic deformation of stainless steel. The thickness difference of circumferential carburized layer in the deformation zone is larger than that near the finishing zone. Furthermore, a lot of contaminants cannot be completely metallurgically bonded between 20% and 30% reduction ratios; the contaminants near the bonding layer are refined and completely bonded metallurgically between 30% and 60% reduction ratios; the contaminants are further refined above 60% to 70% reduction ratio

A Study on the Ultimate Strength and Failure Mode of Stiffened Panels

Different buckling failure modes of stiffened panels will result in differences in ultimate strengths. In this study, the benchmark model of the bottom of bulk carrier with appropriate initial imperfections, boundary conditions and mesh size are selected for a series of non-linear FE analyses. A failure mode discrimination method considering the change rule of ultimate strength and the stress and strain distribution of stiffened plates in ultimate limit state is proposed, and then the boundary function of the failure modes composed of four key parameters, λ, β, hw/tw, λe, is established. Based on this boundary function, the rapid identification of failure modes and the classification of ultimate strength under different failure modes can be realized. Furthermore, the ultimate strength formulas of stiffened panels for different failure modes are obtained by data analysis from many nonlinear finite element analyses

Ionic Current Behaviors of Dual Nano- and Micropipettes

Ionic current rectification (ICR) phenomena within dual glass pipettes are investigated for the first time. We demonstrate that the ionic flow presents different behaviors in dual nano- and micropipettes when the two channels are filled with the same electrolyte KCl and hung in air. Bare dual nanopipettes cannot rectify the ionic current because of their geometric symmetry, but the ICR can be directly observed based on bare dual micropipettes. The phenomena based on dual micropipettes could be explained by the simulation of the Poisson-Nernst-Plank equation. After modification with different approaches, the dual nanopipettes have asymmetric charge patterns and show various ICR behaviors. They have been successfully employed to fabricate various nanodevices, such as ionic diodes and bipolar junction transistors. Due to the simple and fast fabrication with high reproducibility, these dual pipettes can provide a novel platform for controlling ionic flow in nano- and microfluidics, fabrication of novel nanodevices, and detection of biomolecules

Global epidemiology of animal influenza infections with explicit virus subtypes until 2016: A spatio-temporal descriptive analysis

Influenza virus, with a global distribution, diverse animal host range and multiple virus subtypes, has caused several pandemics. To better prepare for the emergence of new subtypes and the possible threat of the next pandemic, the global status of animal influenza must be defined and documented. We created a global database of animal influenza events by searching scientific databases and the primary literature on animal influenza-related events up to and including 2016. The temporal, spatial and host distribution of animal influenza and the diversity of influenza subtypes in different regions were analyzed. A total of 70,472 records and 4712 events of animal influenza throughout the world were identified. Events involving subtypes H5N2, H7N7 and H7N9 were relatively constant, with a slow upward trend during the past decade. Asia was the region with the most clusters of events. Poultry was the main host reported in Asia and Africa, and wild birds in Europe and North America. We found that wild birds carried a very rich array of virus subtypes, a warning for the possible generation of reassortment viruses with pandemic potential. Influenza virus subtype diversity - a risk for virus reassortment - was greatest in Asia, North America and Europe. Our database provides a comprehensive overview of the historical and current status of animal influenza events throughout the world. Influenza surveillance needs to be strengthened in some countries and regions to prevent the emergence of new subtypes. Importantly, improvement of the global influenza surveillance system and structures to enable sharing of surveillance data is very much needed to prepare for the next pandemic