共检索到 34

The aerosol scattering phase function (ASPF), a crucial element of aerosol optical properties, is pivotal for radiative forcing calculations and aerosol remote sensing detection. Current detection methods for the ASPF include multi-sensor detection, single-sensor rotational detection and imaging detection. However, these methods face challenges in achieving high-resolution full-angle measurement, particularly for small forward (i.e., less than 10 degrees) or backward (i.e., more than 170 degrees) scattering angles in open path. In this work, a full-angle ASPF detection system based on the multi-field-of-view Scheimpflug lidar technique has been proposed and demonstrated. A 450 nm continuous-wave semiconductor laser was utilized as the light source and four CMOS image sensors were employed as detectors. To detect the full-angle ASPF, four receiving units capture angular scattering signals across different angle ranges, namely 0 degrees-20 degrees, 10 degrees-96 degrees, 84 degrees-170 degrees, 160 degrees-180 degrees, respectively. The influence of the relative illumination and angular response of the used image sensors have been corrected, and a signal stitching algorithm was developed to obtain a complete 0-180 degrees angular scattering signal. Atmospheric measurements have been conducted by employing the full-angle ASPF detection system in open path. The experimental results of the ASPF have been compared with the AERONET data from the Socheongcho station and simulated ASPF based on the typical aerosol models in mainland China, showing excellent agreement. The promising results demonstrated in this work have shown a great potential for detecting the full-angle ASPF in open path.

期刊论文 2025-12-01 DOI: 10.1016/j.optlastec.2025.113386 ISSN: 0030-3992

Distinguishing the origin of lunar water ice requires in situ isotopic measurements with high sensitivity and robustness under extreme lunar conditions; however, challenges such as uncertain water contents and isotopic fractionation induced by regolith particles restrict isotopic analysis. Herein, we present a miniaturized tunable diode laser absorption spectrometer (TDLAS) developed as the core prototype for the Chang'E-7 Lunar Soil Water Molecule Analyzer (LSWMA). The wavelength range of the instrument is 3659.5-3662.0 cm-1, and the system integrates a Herriott cell for stable multi-isotope (H2 16O, H2 18O, H2 17O, and HD16O) detection and employs regolith samples of known isotopic experiments to quantify adsorption-induced fractionation. Performance evaluations demonstrated a dynamic water detection range of 0.01-2 wt % and isotope precision up to 1.3 parts per thousand for delta D (30.5 s), 0.77 parts per thousand for delta 18O (36 s), and 0.75 parts per thousand for delta 17O (21.5 s) with extended averaging. Repeated injections of three types of standard water revealed a volume-dependent deviation (Delta delta D up to -59.5 parts per thousand) attributed to multilayer adsorption effects, while simulated lunar soil experiments identified additional isotopic fractionation (Delta delta D up to -12.8 parts per thousand) caused by particle binding. These results validate the ability of the spectrometer to resolve subtle isotopic shifts under lunar conditions, providing critical data for distinguishing water origins and advancing future resource utilization strategies.

期刊论文 2025-06-10 DOI: 10.1021/acssensors.5c01115 ISSN: 2379-3694

Meteorites provide access to information on the formation and evolution of planetary bodies which is otherwise difficult to study. The unique nature of these samples and their relative scarcity means that non-destructive analysis techniques are needed to study their properties. This paper uses the laser ultrasound technique spatially resolved acoustic spectroscopy to non-destructively determine both the crystal orientation and the single crystal elastic constants (Cif) of a sample of the Gibeon meteorite. There are no published values to directly compare the results of this study, as non-destructive measurements of the single crystal elasticity on granular material have not been possible. Therefore, comparisons with theoretical values for man-made iron-nickel alloys are given showing the Cif values are in the expected range. There are studies providing bulk elastic properties of meteorites, and so calculated bulk properties derived from the single crystal elasticity measurements are compared and also agree well.

期刊论文 2025-06-01 DOI: 10.1016/j.scriptamat.2025.116666 ISSN: 1359-6462

The construction of a lunar base requires a huge amount of material, which cannot be entirely transported from Earth. Therefore, technologies are needed to build with locally available resources, such as the lunar regolith. One approach is to directly melt the lunar regolith on the surface and under the vacuum condition of the Moon, using laser radiation. In this article, a lunar regolith simulant is laser beam melted to two-dimensional singlelayer-structures using different ambient pressures from 0.05 mbar to 2000 mbar, laser process parameters from 60 W to 100 W laser power, and 1 mm s- 1 to 3 mm s- 1 feed rates. Additionally, the influence of the ambient gas was investigated using argon as an air alternative. The results show that the ambient pressure on the Moon is not negligible when studying the melting processes of lunar regolith on Earth. With decreasing ambient pressure, the appearance of the melted regolith simulant varies from a shiny to a matt surface. At the highest laser energy density, the thickness of a single-layer increases from 2.6 +/- 0.4 mm to 5.3 +/- 0.3 mm and the porosity of the melted regolith increases from 17.2 % to 52.2 % with decreasing ambient pressure. Additionally, mechanical properties are determined using 3-point bending tests. The maximum bending strength decreases by 60 % with the increased ambient pressure from 10 mbar to 2000 mbar. Consequently, the development of in-situ resource utilization technologies, which process the lunar regolith directly on the lunar surface, must consider the ambient pressure on the Moon. Otherwise, the processes will not work as expected from the experiments in Earth-based laboratories.

期刊论文 2025-03-01 DOI: 10.1016/j.actaastro.2024.11.057 ISSN: 0094-5765

In order to overcome the obstacles of poor wear resistance and complex preparation process of the traditional tillage soil-engaging parts, this study presents a powder laying-feeding multi-material additive manufacturing method based on selective laser melting (SLM), to fabricate the heterogeneous material tillage parts with 316 L stainless steel (316 L) as the part-body and high entropy alloys (HEAs)-diamond composites as the part-blade. The microstructures including SLM forming quality, interfacial bonding of heterogeneous material, graphitization of diamond and interfacial behavior of diamond/HEAs matrix are systematically investigated. The results indicate that, adopting medium laser energy density 79.4 J/mm(3) of the composites during same-layer deposition, the overlapping area of 316 L/composites exhibits metallurgical bonding with high relative density of the composites section. Only slight graphitization of diamond happens and similar to 2 mu m width diffusion zone forms between diamond and HEAs matrix, without harmful carbide formation. Moreover, compared with commercial 65Mn steel, the wear resistance (wear mass loss rate) and corrosion resistance (corrosion current density) of HEAs-diamond composites have been decreased by 28 times and 230 times, respectively. The hetero-material 316L-composites exhibits good interfacial bonding strength of 432.3 MPa with elongation of 11.2 %. This study not only results in a novel solution of tillage wear-resisting parts, but also provides a multi-material additive manufacturing technology for metallic heterogeneous components.

期刊论文 2025-02-05 DOI: 10.1016/j.jallcom.2025.178723 ISSN: 0925-8388

Permanently shadowed regions (PSRs) on the Moon are potential reservoirs for water ice, making them hot spots for future lunar exploration. The water ice in PSRs would cause distinctive changes in space weathering there, in particular reduction-oxidation processes that differ from those in illuminated regions. To determine the characteristics of products formed during space weathering in PSRs, the lunar meteorite NWA 10203 with artificially added water was irradiated with a nanosecond laser to simulate a micrometeorite bombardment of lunar soil containing water ice. The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness, poor stratification, the appearance of bubbles, and a reduced number of npFe0. Additionally, EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles (npFe0) in the amorphous rim with the involvement of water. The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface. In addition, it offers a reference for a new space weathering model that incorporates water in PSRs, which could be widespread on asteroids with volatiles.

期刊论文 2025-02-01 DOI: 10.1007/s11631-024-00746-7 ISSN: 2096-0956

Determining water concentrations in the polar regions of the Moon is one of the priority tasks of a number of space missions and, in particular, the Luna-27 mission. The complex of scientific equipment of the Luna-27 spacecraft includes time-of-flight laser ionization mass spectrometer LASMA-LR, the main task of which is to analyze the elemental composition of the regolith at the landing site. The design and configuration of the flight instrument is adapted for the analysis of regolith and was not originally intended for the study of volatile compounds. However, due to the importance of determining the water content in regolith, we reviewed some approaches to analyzing samples during lunar missions and assessed the applicability of LASMA-LR and the laser ionization mass spectrometry method in general for identifying water in regolith. It has been established that using this instrument it is possible to detect water in regolith, including determining its state (chemically bound and unbound water). Moreover, the conditions for sampling the regolith and delivering it to the soil receiving device of the instrument are critically important for the analysis, since under the conditions of the lunar surface, sublimation of ice is possible before the samples are analyzed. This technique has advantages over some other methods of analyzing water and/or ice used in space experiments, and can be used in the study of a number of planets and bodies of the Solar System.

期刊论文 2024-10-01 DOI: 10.1134/S0038094624700436 ISSN: 0038-0946

The study of volatiles and the search for water are the primary objectives of the Luna-27 mission, which is planned to land on the south pole of the Moon in 2028. Here we present the tunable Diode Laser Spectrometer (DLS-L) that will be onboard the lander. The DLS-L will perform isotopic analysis of volatiles that are pyrolytically evolved from regolith. This article dives into the design of the spectrometer and the characterisation of isotopic signature retrieval. We look forward to expanding our knowledge of Lunar geochemistry by measuring D/H, 18O/17O/16O, 13C/12C ratios in situ, which would be the one-of-a-kind direct study of the lunar soil isotopy without sample contamination.

期刊论文 2024-09-01 DOI: 10.1016/j.pss.2024.105935 ISSN: 0032-0633

Sudden leaks often occur when constructing shield tunnels within saturated sandy cobble strata. Therefore, it is important to examine the reasons for water seepage and understand the mechanisms behind such problems. This paper presents a study that combines laser scanning technology with the Python programming language to create software for monitoring tunnel deformation. The software was employed in a practical subway tunnel scenario, successfully acquiring deformation data pertaining to the tunnel's structural segment through the analysis of point cloud data from the tunnel lining. Furthermore, the seepage-stress coupling theory was employed to establish a three-dimensional model of shield tunnel excavation, interlinking groundwater and stratigraphic factors with the sequence of shield tunnel excavation. The origins and mechanisms of water damage resulting from seepage and leakage are explicated through an examination of the seepage field, displacement field, and deformation of the tunnel structure pre- and post-excavation. Additionally, on-site monitoring data is considered. The mechanism of tunnel leakage is outlined as follows: Tunnel excavation completion induces alterations in the seepage field, leading to an accelerated inflow of groundwater into the soil beneath the tube sheet during shield excavation. The tube sheet of the shield tunnel, composed of sand and gravel layers, experiences vertical elliptical deformation that exacerbates shifts in the displacement field due to tunnel deformation's inception and progression. Excessive tube sheet deformation triggers fracture cracks, ultimately engendering the creation of seepage channels. These channels, in turn, foster seepage and water damage. The results of this paper provide a reference for preventing and remedying water infiltration and leakage in shield tunnels constructed of sandy cobble strata.

期刊论文 2024-07-01 DOI: 10.1016/j.tust.2024.105784 ISSN: 0886-7798

Carbonate minerals are ubiquitous in nature, and their dissolution impacts many environmentally relevant processes including preferential flow during geological carbon sequestration, pH buffering with climate-change induced ocean acidification, and organic carbon bioavailability in melting permafrost. In this study, we advance the atomic level understanding of calcite dissolution mechanisms to improve our ability to predict this complex process. We performed high pressure and temperature (1300 psi and 50 degrees C) batch experiments to measure transient dissolution of freshly cleaved calcite under H2O, H+, and H(2)CO(3)(-)dominated conditions, without and with an inhibitory anionic surfactant present. Before and after dissolution experiments, we measured dissolution etch-pit geometries using laser profilometry, and we used density functional theory to investigate relative adsorption energies of competing species that affect dissolution. Our results support the hypothesis that calcite dissolution is controlled by the ability of H2O to preferentially adsorb to surface Ca atoms over competing species, even when dissolution is dominated by H+ or H2CO3. More importantly, we identify for the first time that adsorbed H+ enhances the role of water by weakening surface Ca-O bonds. We also identify that H2CO3 undergoes dissociative adsorption resulting in adsorbed HCO3- and H+. Adsorbed HCO3- that competes with H2O for Ca acute edge sites inhibits dissolution, while adsorbed H+ at the neighboring surface of CO3 enhances dissolution. The net effect of the dissociative adsorption of H2CO3 is enhanced dissolution. These results will impact future efforts to more accurately model the impact of solutes in complex water matrices on carbonate mineral dissolution.

期刊论文 2024-06-22 DOI: 10.1021/acs.est.4c00162 ISSN: 0013-936X
  • 首页
  • 1
  • 2
  • 3
  • 4
  • 末页
  • 跳转
当前展示1-10条  共34条,4页