We investigate the ground- and excited-state properties of a two-dimensional charge-ordering system, and theoretically demonstrate that multielectron excitations by one photon occur substantially as ...a result of frustration effects. These multielectron excitations are naturally regarded as domain excitations, which involve a simultaneous excitation of a part of the system lattice. Furthermore, we show that such domain excitations not only suppress the original charge-ordering phase strongly but also enhance another phase of charge ordering. As a result of such a global change, the overall photoinduced optical conductivity spectra are also modified drastically from the original spectrum, with the modified spectra exhibiting midgap and gapless features.
•Tunnel blasting tests were conducted using advanced electronic detonators.•The superposition method reproduced the vibration waveforms in delay blasting.•The optimum delay interval was obtained from ...the waveform in single-shot blasting.•The vibration reduction method was validated at another tunnel construction site.
Blasting has been widely used for economical and rapid rock excavation in civil and mining engineering but has great loads, such as vibrations and noises, on the surrounding environment in the case of urban areas near dwellings and important structures. In this study, for the purpose of environmental load reduction, blasting tests were conducted at a tunnel construction site using advanced electronic detonators in which arbitrary ignition times could be set. The test results showed that the peak amplitude of the vibration waveform from each of the blast holes follows the Weibull distribution and that the wave propagation time depends on the location of the blast hole on the tunnel face. The superposition method proposed from these findings reproduced the vibration waveforms in delay blasting from the seed waveform recorded in single-shot blasting. The optimum delay interval determined accurately from the superposition method was almost equal to the one simply estimated from the method with the autocorrelation coefficient or a frequency analysis of the vibration waveform in single-shot blasting. These simple methods were validated at another tunnel construction site and found to be useful for estimating the optimum delay interval from single-shot blasting at each tunnel face on each day. This study is based on the practical consideration of actual tunnel blasting and construction, and these proposed methods will be widely applied to other tunnel construction sites.
•Tabs do not only enhance but also suppress jet entrainment and diffusion.•Tabs generally decreases entrainment velocity represented by velocity gradient.•Entrainment area significantly affects the ...entrainment rate.•Directional characteristics of jet diffusion can be controlled by optimizing tabs.
Effects of half delta-wing tabs on mixing and diffusion in an axisymmetric jet are experimentally investigated. The tabs are installed at the jet exit circumferentially with an equal interval. The number of the tab is varied from 1 to 6. The jet Reynolds number is set to 20,000. Instantaneous streamwise and radial (vertical or horizontal) velocities and temperature are mainly measured by a composite probe which consists of an X-type hot-wire and an I-type cold-wire. The results show that mixing with the ambient fluid is more enhanced with increasing the number of the tab near the jet exit. However, in the downstream region, it is suppressed in the cases with 4, 5, and 6 tabs and most suppressed in the case with 6 tabs, while it is most enhanced in the case with 3 tabs. The analysis based on the mean velocity distribution indicates that, although the spatially-averaged entrainment velocity is basically decreased by the tabs, the mixing and entrainment can be enhanced when the entrainment area is significantly increased. Thermal diffusion is more enhanced with increasing the number of the tab near the jet exit but, in the downstream region, it is equivalent or suppressed in the cases with the tabs. These results are caused by the mixed effects of the tabs: enhancement of not only mixing and diffusion but also the energy dissipation. The present study suggests that it is feasible to both promote and suppress mixing of the jet by the half delta-wing tabs, and directional characteristics of the jet diffusion can be controlled by optimizing configuration of the tabs.
We propose the detection of domain dynamics in a one-dimensional system by using high energy photons such as synchrotron radiation. The domain here means that of a different phase formed in the ...background of an original phase. Using high energy photons, it is expected that not only k=0 states with k being the momentum of its center of gravity motion, but also finite k states are possible to be detected. We theoretically demonstrate how they are observed, with nonresonant inelastic x-ray scattering and valence photoemission as concrete examples. In the former, we mainly detect charge excitations, particularly, the center of gravity and the spatial size of the domain as its basic two degrees of freedom, while, in the latter, spin excitations inside the domain also play an essential role.
Croconic acid crystals show proton displacive-type ferroelectricity with a large spontaneous polarization reaching 20 μC/cm^{2}, which originates from the strong coupling of proton and π-electron ...degrees of freedom. Such a coupling makes us expect a large polarization change by photoirradiations. Optical-pump second-harmonic-generation-probe experiments reveal that a photoexcited croconic-acid crystal loses the ferroelectricity substantially with a maximum quantum efficiency of more than 30 molecules per one absorbed photon. Based on density functional calculations, we theoretically discuss possible pathways toward the formation of a one-dimensional domain with polarization inversion and its recovery process to the ground state by referring to the dynamics of experimentally obtained polarization changes.
•Investigation of the dissipation scaling in the spatially developing mixing layer.•The scaling law differs between the upstream and downstream.•Dissipation coefficient of the turbulent kinetic ...energy Cε changes in the upstream.•Cϵ becomes a constant when large-scale structures reach a self-similarity.
Direct numerical simulation is conducted for a spatially developing shear mixing layer to investigate the spatial transition of the dissipation coefficient of the turbulent kinetic energy, Cϵ. The scaling law suggested by Goto and Vassilicos Phys. Rev. E 94, 053108 (2016), Cϵ∼Reλ−1, holds over a wide area in the upstream region (0.3 ≤ x/L0 ≤ 1.9, where x is the streamwise direction and L0 is the height of the computational domain), and Cϵ takes a constant value in the further downstream region, where Reλ is the turbulent Reynolds number based on Taylor’s microscale. Proper orthogonal decomposition (POD) analysis is performed to investigate the distributions of the streamwise length of the large-scale energy-containing structure, which is estimated from the cycle of the zero-crossing point of the time-series data composed of the sum of the POD modes until the cumulative energy rate exceeds 60 %. It is shown that Cϵ becomes a constant when the distributions of the length of the large-scale structure reach a self-similar state. This result suggests that it is necessary to satisfy the self-similarity of the distribution of the length of the large-scale energy-containing structure in order to apply the condition that Cϵ is a constant.
Ultrafast photoinduced transitions of a one-dimensional Mott insulator into two distinct electronic phases, metal and charge-density-wave (CDW) state, were achieved in a bromine-bridged Pd-chain ...compound Pd(en)2Br(C5-Y)2H2O (en=ethylenediamine and C5-Y=dialkylsulfosuccinate), by selecting the photon energy of a femtosecond excitation pulse. For the resonant excitation of the Mott-gap transition, excitonic states are generated and converted to one-dimensional CDW domains. For the higher-energy excitation, free electron and hole carriers are produced, giving rise to a transition of the Mott insulator to a metal. Such selectivity in photoconversions by the choice of initial photoexcited states opens a new possibility for the developments of advanced optical switching and memory functions.
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