Large-eddy Simulation of Near-field Dynamics in a Particle-laden Round Turbulent Jet

AbstractThis article investigates the near-field dynamics in a particle-laden round turbulent jet in a large-eddy simulation (LES). A point-force two-way coupling model is adopted in the simulation to reveal the particle modulation of turbulence. The particles mainly excite the initial instability of the jet and bring about the earlier breakup of vortex rings in the near-field. The flow fluctuating intensity either in the axial or in the radial directions is hence increased by particles. The article also describes the mean velocity modulated by particles. The changing statistical velocity induced by particle modulation implies the effects of modulation of the local flow structures. This study is expected to be useful to the control of two-phase turbulent jets

Fast Numerical Solutions of Gas-Particle Two-Phase Vacuum Plumes

The free molecule point source and Simons models coupled to the particle Lagrangian trajectory model are employed, respectively, to establish the fast solving method for gas-particle two-phase vacuum plumes. Density, velocity and temperature distributions of gas phase, and velocity and temperature of particles are solved to present the flow properties of two-phase plumes. The method based on free molecule point source model predicts the velocity and temperature distributions of vacuum plumes more reasonably and accurately than the Simons model. Comparisons of different drag coefficients show that Loth's drag formula can calculate exactly particle initial acceleration process for high Rer and Mr two-phase flows. The response characteristics of particles along their motion paths are further analyzed. Smaller particles can easily reach momentum equilibrium, while larger ones accelerate very difficultly. The thermal response is more relaxed than momentum response for different particle sizes. The present study is guidable to consider the effects of two-phase plumes on spacecraft in engineering

Stability analysis of backfilling in subsiding area and optimization of the stoping sequence

AbstractIn underground mining by sublevel caving method, the deformation and damage of the surface induced by subsidence are the major challenging issues. The dynamic and soft backfilling body increases the safety risks in the subsiding area. In this paper, taking Zhangfushan iron mine as an example, the ore body and the general layout are focused on the safety of backfilling of mined-out area. Then, we use the ANSYS software to construct a three-dimensional (3D) model for the mining area in the Zhangfushan iron mine. According to the simulation results of the initial mining stages, the ore body is stoped step by step as suggested in the design. The stability of the backfilling is back analyzed based on the monitored displacements, considering the stress distribution to optimize the stoping sequence. The simulations show that a reasonable stoping sequence can minimize the concentration of high compressive stress and ensure the safety of stoping of the ore body

Split Time Series into Patches: Rethinking Long-term Series Forecasting with Dateformer

Time is one of the most significant characteristics of time-series, yet has received insufficient attention. Prior time-series forecasting research has mainly focused on mapping a past subseries (lookback window) to a future series (forecast window), and time of series often just play an auxiliary role even completely ignored in most cases. Due to the point-wise processing within these windows, extrapolating series to longer-term future is tough in the pattern. To overcome this barrier, we propose a brand-new time-series forecasting framework named Dateformer who turns attention to modeling time instead of following the above practice. Specifically, time-series are first split into patches by day to supervise the learning of dynamic date-representations with Date Encoder Representations from Transformers (DERT). These representations are then fed into a simple decoder to produce a coarser (or global) prediction, and used to help the model seek valuable information from the lookback window to learn a refined (or local) prediction. Dateformer obtains the final result by summing the above two parts. Our empirical studies on seven benchmarks show that the time-modeling method is more efficient for long-term series forecasting compared with sequence modeling methods. Dateformer yields state-of-the-art accuracy with a 40% remarkable relative improvement, and broadens the maximum credible forecasting range to a half-yearly level

The spectrum of low-pTp_{T} J/ψJ/\psi in heavy ion collisions in a fractal description

Transverse momentum spectrum of particles in hadron gas are affected by flow, quantum and strong interaction effects. Previously, most models focus on only one of the three effects but ignore others. The unconsidered effects are taken into the fitted parameters. In this paper, we study the three effects together from a new fractal angle by physical calculation instead of data fitting. Near the critical temperature, the three effects induce $J/\psi$ and neighboring meson to form a two-meson structure. We set up a two-particle fractal (TPF) model to describe this structure. We propose that under the three effects, $J/\psi$-$\pi$ two-meson state, $J/\psi$ and $\pi$ two-quark states form a self-similarity structure. With evolution, the two-meson structure disintegrate. We introduce an influencing factor $q_{fqs}$ to describe the flow, quantum and strong interaction effects and an escort factor $q_2$ to describe the binding force and the three effects. By solving the probability and entropy equations, we obtain the values of $q_{fqs}$ and $q_2$ at different collision energies and centrality classes. By substituting the value of $q_{fqs}$ into distribution function, we obtain the transverse momentum spectrum of low-$p_T$ $J/\psi$ and find it in good agreement with experimental data. We also analyze the evolution of $q_{fqs}$ with the temperature. It is found that $q_{fqs}$ is larger than 1. This is because the three effects decrease the number of microstates. We also find $q_{fqs}$ decreases with decreasing the temperature. This is consistent with the fact that with the system expansion, the influence of the three effects decrease.Comment: 9 pages, 3 figure

Synthesis and antiviral activity of a series of novel N-phenylbenzamide and N-phenylacetophenone compounds as anti-HCV and anti-EV71 agents

AbstractA series of novel N-phenylbenzamide and N-phenylacetophenone compounds were synthesized and evaluated for their antiviral activity against HCV and EV71 (strain SZ-98). The biological results showed that three compounds (23, 25 and 41) exhibited considerable anti-HCV activity (IC50=0.57–7.12μmol/L) and several compounds (23, 28, 29, 30, 31 and 42) displayed potent activity against EV71 with the IC50 values lower than 5.00μmol/L. The potency of compound 23 (IC50=0.57μmol/L) was superior to that of reported compounds IMB-1f (IC50=1.90μmol/L) and IMB-1g (IC50=1.00μmol/L) as anti-HCV agents, and compound 29 possessed the highest anti-EV71 activity, comparable to the comparator drug pirodavir. The efficacy in vivo and antiviral mechanism of these compounds warrant further investigations

GPI-anchored single chain Fv - an effective way to capture transiently-exposed neutralization epitopes on HIV-1 envelope spike

<p>Abstract</p> <p>Background</p> <p>Identification of broad neutralization epitopes in HIV-1 envelope spikes is paramount for HIV-1 vaccine development. A few broad neutralization epitopes identified so far are present on the surface of native HIV-1 envelope spikes whose recognition by antibodies does not depend on conformational changes of the envelope spikes. However, HIV-1 envelope spikes also contain transiently-exposed neutralization epitopes, which are more difficult to identify.</p> <p>Results</p> <p>In this study, we constructed single chain Fvs (scFvs) derived from seven human monoclonal antibodies and genetically linked them with or without a glycosyl-phosphatidylinositol (GPI) attachment signal. We show that with a GPI attachment signal the scFvs are targeted to lipid rafts of plasma membranes. In addition, we demonstrate that four of the GPI-anchored scFvs, but not their secreted counterparts, neutralize HIV-1 with various degrees of breadth and potency. Among them, GPI-anchored scFv (X5) exhibits extremely potent and broad neutralization activity against multiple clades of HIV-1 strains tested. Moreover, we show that GPI-anchored scFv (4E10) also exhibited more potent neutralization activity than its secretory counterpart. Finally, we demonstrate that expression of GPI-anchored scFv (X5) in the lipid raft of plasma membrane of human CD4⁺T cells confers long-term resistance to HIV-1 infection, HIV-1 envelope-mediated cell-cell fusion, and the infection of HIV-1 captured and transferred by human DCs.</p> <p>Conclusions</p> <p>Thus GPI-anchored scFv could be used as a general and effective way to identify antibodies that react with transiently-exposed neutralization epitopes in envelope proteins of HIV-1 and other enveloped viruses. The GPI-anchored scFv (X5), because of its breadth and potency, should have a great potential to be developed into anti-viral agent for HIV-1 prevention and therapy.</p