Employing friction stir welding (FSW) technology to join small plate blanks into larger ones, followed by a spinning process, adeptly surpasses the dimensional constraints of traditionally rolled ...plate blanks. This innovative approach paves the way for the fabrication of large and super-sized thin-walled rotary components, with significant implications in the aerospace sector. In this methodology, the number and layout of welds critically influence the precision of forming in spun workpieces, which could be pivotal in the success of spun tailor-welded blanks (TWBs). Consequently, dedicated experimental research into the spin forming of TWBs, varying in weld numbers and configurations, is essential. This investigation employed annealed 2195 Al–Li alloy plates as the material for experimentation. Four types of blanks with varying weld distributions and increasing weld numbers were designed, prepared through multiple FSW processes, followed by spinning. Comprehensive measurements of weld torsion angles, surface morphology, thickness variations, and forming accuracy of the workpieces post-spinning were conducted. The results show that with the increase of the number of welds, the weld torsion angle of the workpiece after spinning decreases. The spinning process can significantly reduce the surface morphology of the weld area. The thickness of the weld area is thinner than that of the non-weld area, and the superposition of the welds will aggravate the thickness reduction. In addition, the accuracy deviation of the workpiece mainly occurs in the initial and final stages of spinning forming. A negative accuracy deviation occurs at the beginning of the spinning, and a positive accuracy deviation is observed at the end of the spinning stage. In the spinning stage, the welding area appears slight bulge. As the number of welding seams increases, the accuracy of the workpiece decreases.
In this paper, we construct a uniform formula for the Riemann solutions of the simplified Chapman-Jouguet model. Firstly, we define a new functional, and then, we obtain that the Riemann solutions ...can be expressed by the maximum value point of this functional, while Riemann solutions may contain some of strong detonation waves, Chapman-Jouguet detonation waves and contact discontinuities. Finally, Chapman-Jouguet deflagration waves are also discussed.
In this article, we prove the existence and obtain the expression of its solution formula of global smooth solution for non-homogeneous multi-dimensional（m-D） conservation law with unbounded initial ...value; our methods are new and essentially different with the situation of bounded initial value.
Utilizing multi-pass friction stir processing with recirculating water cooling, pure copper plates were processed to successfully synthesize catalysts with distinct grain sizes. An exhaustive ...investigation into their intrinsic structures and properties was conducted. Analyses using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) revealed that Cu-4.85 exhibits a preferred (111) crystallographic orientation along with a high dislocation density. Transmission electron microscopy (TEM) images clearly identified the types of dislocations present within Cu-4.85. Density functional theory (DFT) calculations further demonstrated that Cu-4.85 displays lower Gibbs free energy at the hollow site on the (111) plane, thereby facilitating the H* adsorption process. Collectively, this study delves into the cooperative influence of grain size, crystal orientation and dislocation density on the electrocatalytic hydrogen evolution (HER) performance. It was found that Cu-4.85 demonstrates exceptional HER activity, characterized by a reduced overpotential and a low Tafel slope. The study elucidates the mechanism of H atom adsorption in Cu-4.85 during the HER process, furnishing theoretical foundations for enhancing HER catalytic performance and offering significant theoretical and experimental insights for the design and fabrication of copper catalytic electrodes.
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•Underwater FSP produced Cu-4.85 with (111) orientation and high dislocation density.•Grain size orientation and dislocation density synergistically enhance HER performance.•DFT shows lower Gibbs free energy for H* adsorption at (111) hollow sites.
We investigate the global expression and structure of admissible weak solutions of an n dimensional non-homogeneous scalar conservation law with the initial data that has two constant states, ...separated by an n−1 dimensional smooth manifold. We obtain the unique global existence of non-self-similar solutions. It is the first result about the global structure of non-self-similar shock waves and rarefaction waves of n dimensional non-homogeneous scalar conservation law. The shock wave and the rarefaction wave can be directly expressed and studied by a global implicit function. Finally, we give some applications to discover some interesting phenomena.
We are concerned with the minimal entropy conditions for one-dimensional scalar conservation laws with general convex flux functions. For such scalar conservation laws, we prove that a single ...entropy-entropy flux pair
(
η
(
u
)
,
q
(
u
)
)
(\eta (u),q(u))
with
η
(
u
)
\eta (u)
of strict convexity is sufficient to single out an entropy solution from a broad class of weak solutions in
L
l
o
c
∞
L^\infty _{\mathrm { loc}}
that satisfy the inequality:
η
(
u
)
t
+
q
(
u
)
x
≤
μ
\eta (u)_t+q(u)_x\leq \mu
in the distributional sense for some non-negative Radon measure
μ
\mu
. Furthermore, we extend this result to the class of weak solutions in
L
l
o
c
p
L^p_{\mathrm {loc}}
, based on the asymptotic behavior of the flux function
f
(
u
)
f(u)
and the entropy function
η
(
u
)
\eta (u)
at infinity. The proofs are based on the equivalence between the entropy solutions of one-dimensional scalar conservation laws and the viscosity solutions of the corresponding Hamilton-Jacobi equations, as well as the bilinear form and commutator estimates as employed similarly in the theory of compensated compactness.
In this study a new type of plug-in friction-stir lap welding (PFSLW) is proposed to prepare welded joints based on 4-mm-thick 6061-T6 aluminum alloy sheet. The differences in the cross-sectional ...morphology, microstructure, cross-sectional hardness and shear properties between the PFSLW joint and the normal friction-stir lap-welding (FSLW) joint are discussed. The results show that the cross-sectional morphology of the PFSLW joint has undergone changes. The PFSLW joint has a mechanical interlocking structure on the advancing side that is beneficial to the connection strength of the joint. The grain structure differs at the boundary between the thermo-mechanically affected zone (TMAZ) and the heat-affected zone (HAZ), and the PFSLW joints show a more pronounced bending deformation of the grain organization near the boundary. The microhardness of PFSLW joints was increased in the TMAZ and HAZ areas, and the lowest hardness is further away from the center of the weld. The failure load of the PFSLW joint has been improved, the microcracks part of the PFSLW joint has a ridge-like structure. In addition, the actual welding width of PFSLW joints was improved.
We are concerned with the minimal entropy conditions for one-dimensional scalar conservation laws with general convex flux functions. For such scalar conservation laws, we prove that a single ...entropy-entropy flux pair \((\eta(u),q(u))\) with \(\eta(u)\) of strict convexity is sufficient to single out an entropy solution from a broad class of weak solutions in \(L^\infty_{\rm loc}\) that satisfy the inequality: \(\eta(u)_t+q(u)_x\leq \mu\) in the distributional sense for some non-negative Radon measure \(\mu\). Furthermore, we extend this result to the class of weak solutions in \(L^p_{\rm loc}\), based on the asymptotic behavior of the flux function \(f(u)\) and the entropy function \(\eta(u)\) at infinity. The proofs are based on the equivalence between the entropy solutions of one-dimensional scalar conservation laws and the viscosity solutions of the corresponding Hamilton-Jacobi equations, as well as the bilinear form and commutator estimates as employed similarly in the theory of compensated compactness.
Host cellular receptors play key roles in the determination of virus tropism and pathogenesis. However, little is known about SARS-CoV-2 host receptors with the exception of ACE2. Furthermore, ACE2 ...alone cannot explain the multi-organ tropism of SARS-CoV-2 nor the clinical differences between SARS-CoV-2 and SARS-CoV, suggesting the involvement of other receptor(s). Here, we performed genomic receptor profiling to screen 5054 human membrane proteins individually for interaction with the SARS-CoV-2 capsid spike (S) protein. Twelve proteins, including ACE2, ASGR1, and KREMEN1, were identified with diverse S-binding affinities and patterns. ASGR1 or KREMEN1 is sufficient for the entry of SARS-CoV-2 but not SARS-CoV in vitro and in vivo. SARS-CoV-2 utilizes distinct ACE2/ASGR1/KREMEN1 (ASK) receptor combinations to enter different cell types, and the expression of ASK together displays a markedly stronger correlation with virus susceptibility than that of any individual receptor at both the cell and tissue levels. The cocktail of ASK-related neutralizing antibodies provides the most substantial blockage of SARS-CoV-2 infection in human lung organoids when compared to individual antibodies. Our study revealed an interacting host receptome of SARS-CoV-2, and identified ASGR1 and KREMEN1 as alternative functional receptors that play essential roles in ACE2-independent virus entry, providing insight into SARS-CoV-2 tropism and pathogenesis, as well as a community resource and potential therapeutic strategies for further COVID-19 investigations.
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•A membrane catalytic packed-bed reactor was designed for safe scalable alcohol oxidation.•The reactor performance was affected by the oxygen supply.•The main oxygen transfer ...resistance was in the bulk liquid within the bed.•An effectiveness factor was proposed to aid membrane reactor design.
A flat membrane microchannel reactor was designed and demonstrated for the safe and scalable oxidation of solvent-free benzyl alcohol with molecular oxygen on Au-Pd/TiO2 catalyst. The microchannel reactor employed a mesh-supported Teflon AF-2400 membrane, with gas and liquid channels on each side. Catalyst particles were packed in the liquid flow channel. Operation with 20 bara pressure difference between the gas and the liquid phases was possible at 120 °C. Pervaporation of organics through the membrane was experimentally measured to ensure that the organic vapour concentration remained below the lower flammability limit during the reaction. High oxygen pressure was shown to have a positive effect on reactor performance. A conversion of benzyl alcohol of 70% with 71% selectivity to benzaldehyde was obtained at 1150 gcat·s/galcohol, 8.4 bara oxygen pressure and 10 bara liquid pressure. The oxygen consumption rate was not significantly decreased when doubling the membrane thickness, indicating that the membrane generated only low resistance to oxygen mass transfer. When changing the catalyst particle size and the liquid flow rate, no significant effect was observed on the oxidation reaction rate. An effectiveness factor approach is proposed to assess the effect of oxygen permeation and transverse mass transfer on the catalyst packed in the membrane reactor, which suggests that the oxidation of benzyl alcohol on the highly active Au-Pd/TiO2 catalyst is controlled by the oxygen transverse mass transfer in the bulk liquid within the catalyst bed. Scale-up of the flat membrane microchannel reactor was demonstrated through increasing the liquid channel width by approximately ten times, which increased the reactor productivity by a factor of eight.
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