Investigation of Detonative Combustion Characteristics

AbstractThe pressure and deflagration-to-detonation transition (DDT) characteristics of acetylene and oxygen flame were studied in a detonation tube. The pressure history and the flame velocity along the tube were measured with high frequency pressure transducers and ion probes. By analyzing the data recorded in the experiment, the detonation wave pressure, post-wave pressure and DDT distance were obtained, together with the effects of the initial pressure varying from 2 104 Pa to 105 Pa, equivalence ration from 0.3 to 1.0, and mixture concentration from 60% to 100%. It was found that the detonation pressure was decreased respectively with the decrease of initial pressure, equivalence ratio and mixture concentration, but the DDT distance was enlarged. The DDT distance was found particularly sensitive to mixture concentration

Exploring the Υ(6S)→χbJϕ\Upsilon (6S)\rightarrow \chi _{bJ}\phi Υ ( 6 S ) → χ b J ϕ and Υ(6S)→χbJω\Upsilon (6S)\rightarrow \chi _{bJ}\omega Υ ( 6 S ) → χ b J ω hidden-bottom hadronic transitions

In this work, we investigate the hadronic loop contributions to the $\Upsilon(6S) \to \chi_{bJ} \phi~(J=0,1,2)$ along with $\Upsilon(6S) \to \chi_{bJ} \omega~(J=0,1,2)$ transitions. We predict that the branching ratios of $\Upsilon(6S) \to \chi_{b0} \phi$, $\Upsilon(6S) \to \chi_{b1} \phi$ and $\Upsilon(6S) \to \chi_{b2} \phi$ are $(0.68 \sim 4.62) \times 10^{-6}$, $(0.50 \sim 3.43) \times 10^{-6}$ and $(2.22 \sim 15.18) \times 10^{-6}$, respectively and those of $\Upsilon(6S) \to \chi_{b0} \omega$, $\Upsilon(6S) \to \chi_{b1} \omega$ and $\Upsilon(6S) \to \chi_{b2} \omega$ are $(0.15 \sim 2.81) \times 10^{-3}$, $(0.63 \sim 11.68) \times 10^{-3}$ and $(1.08 \sim 20.02) \times 10^{-3}$, respectively. Especially, some typical ratios, which reflect the relative magnitudes of the predicted branching ratios, are given, i.e., for $\Upsilon(6S)\to \chi_{bJ}\phi$ transitions, $\mathcal{R}^\phi_{10}={\mathcal{B}[\Upsilon(6S) \to \chi_{b1} \phi]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b0} \phi]} \approx 0.74$, $\mathcal{R}^\phi_{20}= {\mathcal{B}[\Upsilon(6S) \to \chi_{b2} \phi]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b0} \phi]} \approx 3.28$, and $\mathcal{R}^\phi_{21} = {\mathcal{B}[\Upsilon(6S) \to \chi_{b2} \phi]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b1} \phi]} \approx 4.43$, and for $\Upsilon(6S)\to \chi_{bJ}\omega$ transitions, $\mathcal{R}^\omega_{10}={\mathcal{B}[\Upsilon(6S) \to \chi_{b1} \omega]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b0} \omega]} \approx 4.11$, $\mathcal{R}^\omega_{20}= {\mathcal{B}[\Upsilon(6S) \to \chi_{b2} \omega]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b0} \omega]} \approx 7.06$, and $\mathcal{R}^\omega_{21} = {\mathcal{B}[\Upsilon(6S) \to \chi_{b2} \omega]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b1} \omega]} \approx 1.72$. With the running of BelleII in the near future, experimental measurement of these two kinds of transitions will be a potential research issue.Comment: 10 pages, 10 figures and 1 table. Accepted by Eur. Phys. J.

Realization of the Single-pair-Weyl Phonons with the Maximum Charge Number in Acoustic Crystals

To observe the Weyl phonon (WP) with the maximum charge and to design a realistic material structure containing only single-pair-WPs have long been considered two challenges in the field of topology physics. Here we have successfully designed an acoustic crystal to realize the single-pair-WPs with the maximum charge for the first time. Our theoretical simulations on acoustic band dispersions demonstrate that protected by the time-reversal symmetry ($\cal T$) and the point group symmetries, a WP with the charge -4 ($\mathcal{C}=-4$) and another WP with $\mathcal{C}=+4$ are located at the high-symmetry point $\Gamma$ and R, respectively, with the absence of any other kinds of WPs. Moreover, the singe-pair-WPs obtained here are designed by the simplest two-band mode, and the related quadruple-helicoid Fermi acrs can be observed clearly in experiments, since they aren't covered by any bulk bands and hybridized by other kinds of WPs. Our theoretical results provide a reliable acoustic crystal to study the topological properties of the single-pair-WPs with the maximum charge for experimentalists in this field.Comment: 7 pages; 4 figure