Research on Tomography by Using Seismic Reflection Wave in Laneway

AbstractAs a necessary step and an integral part of works in laneway, the geological prediction is an important means of reducing disaster losses and geological disasters in the works in laneway. This paper mainly discusses tunnel reflection tomography by using seismic reflection wave in laneway. The speed of elastic wave in front of tunnel face and the three-dimensional images can be figured out when the detector check the reflection of elastic wave from the focal points on the tunnel face. The location, size and depth of cave can be ascertained. According to the forecasts of laneway works in the Iron Mine Xishimen, tunnel reflection tomography by using seismic reflection wave can well forecast engineering geology and hydro-geological conditions in front of tunnel face. It will help to supply positive guidance for working plan and construction measures in laneway. Therefore, the construction safety and speed can be ensured, helping to lead to great practical significance and significant economic benefits

4,6-Dimethyl­pyrimidin-2(1H)-one–urea–water (1/1/1)

In the crystal structure of the title compound, C6H8N2O·CH4N2O·H2O, mol­ecules are linked via N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds, forming a three–dimensional framework

Review on the development of kelp industry in Shandong province: A comparative perspective

Shandong and Fujian are two important provinces regarding the development of the seaweed industry, which shared three-fourths of the national seaweed yield in the year 2020. The present study has analyzed the overall situation of the seaweed industry in Shandong and Fujian provinces by comparing annual output, farming area, and species structure. The current status of Laminaria japonica cultivation in two provinces is also compared to the production process, industrial organization, progress, and innovation. On this foundation, the following development strategies are proposed for the seaweed industry in Shandong Province: (1) change the mindset based on the present industrial basis, (2) retain and transform innovative achievements, (3) enhance the services of associations and organizations and (4) construct brands based on current market share

Identifying the Riemann zeros by periodically driving a single qubit

The Riemann hypothesis, one of the most important open problems in pure mathematics, implies the most profound secret of prime numbers. One of the most interesting approaches to solve this hypothesis is to connect the problem with the spectrum of the physical Hamiltonian of a quantum system. However, none of the proposed quantum Hamiltonians have been experimentally feasible.Here, we report the first experiment to identify the first non-trivial zeros of the Riemann zeta function and the first two zeros of P\'olya's fake zeta function, using a novel Floquet method, through properly designed periodically driving functions. According to this method, the zeros of these functions are characterized by the occurrence of crossings of quasi-energies when the dynamics of the system are frozen. The experimentally obtained zeros are in excellent agreement with their exact values. Our study provides the first experimental realization of the Riemann zeros, which may provide new insights into this fundamental mathematical problem.Comment: 5 pages, 7 figure

Chaos-assisted two-octave-spanning microcombs

Since its invention, optical frequency comb has revolutionized a broad range of subjects from metrology to spectroscopy. The recent development of microresonator-based frequency combs (microcombs) provides a unique pathway to create frequency comb systems on a chip. Indeed, microcomb-based spectroscopy, ranging, optical synthesizer, telecommunications and astronomical calibrations have been reported recently. Critical to many of the integrated comb systems is the broad coverage of comb spectra. Here, microcombs of more than two-octave span (450 nm to 2,008 nm) is demonstrated through χ^((2)) and χ^((3)) nonlinearities in a deformed silica microcavity. The deformation lifts the circular symmetry and creates chaotic tunneling channels that enable broadband collection of intracavity emission with a single waveguide. Our demonstration introduces a new degree of freedom, cavity deformation, to the microcomb studies, and our microcomb spectral range is useful for applications in optical clock, astronomical calibration and biological imaging

2,2′-(Butane-1,4-di­yl)diisoquinolinium tetra­chloridozincate(II)

The crystal of the title compound, (C22H22N2)[ZnCl4], consists of 2,2′-(butane-1,4-di­yl)diisoquinolinium organic cations and [ZnCl4]2− complex anions. The cation is located across a twofold axis and the ZnII atom of the anion is located on the other twofold axis. The centroid–centroid distance between parallel pyridine rings of neighboring mol­ecules is 3.699 (3) Å, but the face-to-face separation of 3.601 (3) Å suggests there is no significant π–π stacking in the crystal structure