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A simulation software for efficient analysis and rapid planning of multi-satellite earth observation mission is designed to solve the problem that it is difficult to make fast decisions for multi-target and multi-constraint earth observation mission. The software is developed with C++ programming language, which has the advantages of modular design, good portability, fast running speed and less occupation of resources. Meanwhile, the input and output interfaces of the software adopt the file format of an extensible mark-up language, which can easily realize cross-platform (Windows, Linux, etc.) data exchange. The simulation results show that the software has high execution speed and precision.

In order to reduce the frequency of high-frequency Doppler signal light, the electronic bandwidth of a data acquisition system is reduced. This paper mainly describes the principle and experimental verification results of optical multistage cascade frequency reduction technology. The bandwidth requirement of the detector and the oscilloscope is reduced by the method of "relaying" the measured beat frequency signal between multiple electronic channels. Aiming to achieve the requirement of ultra-high speed measurement of 22 km/s, the requirement of the original signal frequency as high as 28 GHz electrical bandwidth is reduced to the acquisition and recording system with only 8 GHz bandwidth. A complete velocity profile of up to 11.47 km/s is measured on a three-stage light gas gun with velocity measurement accuracy of 1%. [ABSTRACT FROM AUTHOR]

This paper presents a method to enhance extended interaction oscillator (EIO) output power based on a dual-cavity parallel structure (DCPS). This stucture consists of two conventional ladder-line structures in parallel through a connecting structure, which improves the coupling efficiency between the cavities. The dual output power fusion structure employs an H-T type combiner as the output coupler, which can effectively combine the two input waves in phase to further increase the output power. The dispersion characteristics, coupling impedance, and field distribution of the DCPS are investigated through numerical and simulation calculations, and the optimal operating parameters and output structure are obtained by PIC simulation. At an operating voltage of 12.6 kV, current density of 200 A/ cm 2 , and longitudinal magnetic field of 0.5 T, the DCPS EIO exhibits an output power exceeding 600 W at a frequency of 140.6 GHz. This represents a nearly three-fold enhancement compared with the 195 W output of the conventional ladder-line EIO structure. These findings demonstrate the significant improvement in output power and interaction efficiency achieved by the DCPS for the EIO device. [ABSTRACT FROM AUTHOR]

As artificially engineered subwavelength periodic structures, terahertz (THz) metasurface devices exhibit an equivalent dielectric constant and dispersion relation akin to those of natural materials with specific THz absorption peaks, describable using the Lorentz model. Traditional verification methods typically involve testing structural arrays using reflected and transmitted optical paths. However, directly detecting the dielectric constant of individual units has remained a significant challenge. In this study, we employed a THz time-domain spectrometer-based scattering-type scanning near-field optical microscope (THz-TDS s-SNOM) to investigate the near-field nanoscale spectrum and resonant mode distribution of a single-metal double-gap split-ring resonator (DSRR) and rectangular antenna. The findings reveal that they exhibit a dispersion relation similar to that of natural materials in specific polarization directions, indicating that units of THz metasurface can be analogous to those of molecular structures in materials. This microscopic analysis of the dispersion relation of artificial structures offers new insights into the working mechanisms of THz metasurfaces. [ABSTRACT FROM AUTHOR]

The study of high-pressure sound velocity is an important part of shock wave physics, and the study of ultra-high pressure sound velocity of iron is of great significance to many research fields such as geophysics, solid state physics, and crystallography. At present, the measurement of sound velocity is usually carried out by the catch-up sparse wave method and windowed VISAR technology, which is complex in structure and not highly adaptable. In particular, for the ultra-high pressure sonic velocity measurement of metals, it is limited by the loading platform and window materials and cannot realize the high temperature and high-pressure environment of the earth's inner core. In this paper, the sound velocity measurement of iron under high temperature and high-pressure environment (78 GPa) is realized based on the two-stage light gas cannon experimental platform. The side-side sparse wave method was used to establish a coupling model of high-spatially resolved optical group and fiber bundle. A multiplexed all-fiber laser interferometry velocity measurement system (DISAR) was built, and the spatial resolution was better than 20 μm. In this paper, we will provide a feasible route for a method for measuring the high spatiotemporal resolution velocity. [ABSTRACT FROM AUTHOR]