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P-NiSe/MoSe2 exhibits excellent HER properties due to the modulation of the electronic structure by P doping and the synergistic effect arising from the heterostructure.

Context. Olivine responds to space weathering in the fastest and most profound way, which results in significant space weathering spectral alteration effects (SWSAEs) on airless silicate bodies. Although Mg-rich olivine (Fa10) has been subjected to extensive studies, SWSAEs of Fe-rich (Fa# > 20) or Fa-dominant (Fa# ⩾ 50) olivine are still poorly understood. Aims. We aim to systematically characterize the space weathering effects and the associated spectral alterations of Fe-rich olivine on the surface of Phobos and the Moon. Methods. We conducted nanosecond pulsed laser irradiation experiments on a set of synthetic Fe-rich olivine (Fa29, Fa50, Fa71, and Fa100) with energy levels simulated for Phobos and the Moon and analyzed the irradiated olivine for microscopic characteristics and near-infrared (NIR) and Raman spectroscopy. Results. Micron-level thick alteration layers are found in Fa100 compared to those hundreds of nanometers thick in Fa29, Fa50, and Fa71. With increasing irradiation energy levels and Fa# values, nanophase iron (np-Fe0) particles increase in size but decrease in quantity. The np-Fe0 formed via in situ decomposition are ubiquitously present, while those formed via vapor deposition are primarily found in Fa29 but rarely in Fa# ⩾ 50. The size fraction of intermediate (10–40 nm) and large (40–60 nm) np-Fe0 proportionally increases with Fa# values. The NIR spectra of weathered olivine show darkening over reddening in most cases, but Fa100 under the most irradiated condition shows brightening-reddening spectral effects. The Raman spectra of weathered olivine show a reduction in intensity without peak shifts. Conclusions. The Fa# values of olivine are a more critical factor in controlling the SWSAEs on Phobos than those on the Moon. If Phobos and Deimos contain substantial Fe-rich or Fa-dominant olivine, similar to Mars, thick alteration rims and large np-Fe0 formed via space weathering may cause darkening-reddening and potentially brightening-reddening spectral effects on the Martian moons.

Structured light measurement (SLM) has been widely used in acquiring the three-dimensional (3D) shape of objects because of its high precision and high speed. However, the intensity based structured light coding strategies like sinusoidal patterns is difficult to measure transparent and shiny objects with high dynamic range surface reflectance due to inaccurate light intensity information. Divergent multi-line structured light projection and traditional gray-code method avoids this problem by extracting lines. However, traditional gray-code method requires additional many patterns to distinguish the order of lines, which reduces the measurement efficiency. To overcome defects, this paper proposes a line-encoded few-pattern SLM method in measuring shiny and transparent objects. In this method, we simultaneously extract the edge line, the center line and obtain their orders by projecting only five patterns. Many experiments were implemented to prove its accuracy and robustness. Because only five patterns are required, the proposed method greatly accelerate the process of reconstruction, which is indispensable for 3D real-time reconstruction. We conducted a dental model dynamic scanning experiment to prove it.

Phase shifting profilometry (PSP) is widely applied in three-dimensional (3D) shape measurement because of its high precision and simple hardware configuration. However, the gamma effect of commercial digital projector usually causes nonlinear periodical phase error. In this paper, we propose an approach named as Exponential Taylor Series Method (ETSM) to eliminate the gamma distortion. The ETSM sets the input fringe pattern intensity as an exponential Taylor series function. Along with the decoding algorithm proposed, the nonlinear phase error caused by the gamma effect can be eliminated theoretically. Simulations and experiments are conducted to verify the ETSM’s performances by comparing with the conventional method of PSP and another method based on exponent. The results show that the ETSM greatly reduces the phase error caused by gamma distortion without any additional work or pre-process. The ETSM also performs better in resisting the noise due to its quasi-sinusoidal intensity distribution of the captured fringe patterns.

As a generalized extension of Pawlak’s rough set model, the multigranulation decision-theoretic rough set model in ordered information systems utilizes the basic set assignment function to construct probability measure spaces through dominance relations. It is an effective tool to deal with uncertain problems and widely used in practical decision problems. However, when the scale of dataset is large, it takes a lot of time to characterize the approximations of the target concept, as well as complicated calculation processes. In this paper, we develop a novel model called local multigranulation decision-theoretic rough set in an ordered information system to overcome the above-mentioned limitation. Firstly, to reduce the computing time of the information granule independent of the target concept, we only use the characterization of the elements in the target concept to approximate this target concept. Moreover, the corresponding local multigranulation decision-theoretic rough set in an ordered information system is addressed according to the established local model, and the comparisons are made between the proposed local algorithm and the algorithm of original multigranulation decision-theoretic rough set in ordered information systems. Finally, the validity of the local approximation operators is verified through the experimental evaluation using six datasets coming from the University of California-Irvine (UCI) repository.

Phase-based stereo matching (PSM) is a vital step in binocular structured light. PSM is hard to strike a balance between efficiency and accuracy, especially because of the absolute phase matrix’s (APM) double data type. It means that PSM needs more run time and memory than conventional intensity images’ stereo matching. In this paper, we propose a modified absolute difference (AD)-Census algorithm called the fixed window aggregation AD-Census (FWA-AD-Census) to balance the contradiction between efficiency and accuracy in PSM. The FWA-AD-Census aggregates matching cost in a fixed support window instead of an adaptive support window in AD-Census. We analyze the reason why PSM is more suitable to aggregate the matching cost in a fixed support window. Simulations and experiments are conducted to verify the FWA-AD-Census’s performances by comparing the FWA-AD-Census with two other local stereo matching algorithms. One is the AD-Census, which is more accurate but less efficient. Its matching cost is aggregated in an adaptive support window. Another is the sum of absolute difference (SAD), which is more efficient but less accurate, and its matching cost is aggregated in a fixed support window. Theoretical analysis and experimental results both indicate that the proposed algorithm can achieve similar accuracy to the AD-Census with less run time.

The conventional multi-frequency heterodyne method is one of the most widely used methods in non-contact 3D measurement. However, it needs to project different phase-shifting patterns with different frequencies, so a large number of patterns are required. For most conventional methods, the fringe period number of the projected patterns is usually small due to its limited noise tolerance, though a larger fringe period number always means higher accuracy. We propose a two-step phase-shifting demodulation algorithm based on an intensitygradient. In this method, only two patterns for each frequency are required. With the intensity gradient of the two patterns, we obtain the wrapped phase of each frequency. Next, the absolute phase is retrieved from the three wrapped phases with the heterodyne algorithm. Because only two patterns are required for each frequency, the proposed method is more robust and has higher measuring speed compared with the traditional three-frequency four-step heterodyne method. Simulations and experiments prove the feasibility and effectiveness of the method, and demonstrate that the proposed method extends the noise tolerance and achieves highprecision with only half of the patterns required by the traditional three-frequency four-step method.

This paper presents a new fringe projection method for surface-shape measurement that uses novel fringe-width encoded fringe patterns. Specifically, the projection patterns are adjusted with the width of the fringe as the codeword. The wrapped phase with coding information is obtained by using the conventional wrapped phase calculation method, and the fringe order can be identified from the wrapped phase. After the fringe order is corrected based on the region growing algorithm, the fringe order and the wrapped phase can be directly used to reconstruct the surface. Static and dynamic measurements demonstrated the ability of the method to perform 3D shape measurement with only three projected patterns, single camera and projector in the least case.

Without the protection of the atmosphere, the soils on lunar surfaces undergo a series of optical, physical, and chemical changes during micrometeorite bombardment. To simulate the micrometeorite-bombardment process and analyze the impact characteristics, four types of rocks, including terrestrial basalt and anorthosite supposed to represent lunar rock, an H-type chondrite (the Huaxi ordinary chondrite) and an iron meteorite (the Gebel Kamil iron meteorite) supposed to represent micrometeorite impactors, are irradiated by a nanosecond-pulse laser in a high vacuum chamber. Based on laser irradiation experiments, the laser pits are found to be of different shapes and sizes which vary with the rock type. Many melt and vapor deposits are found on the mineral surfaces of all the samples, and nanophase iron (npFe) or Fe-Ni alloy particles are typically distributed on the surfaces of ilmenite, kamacite or other minerals near kamacite. By analyzing the focused ion beam (FIB) ultrathin slices of laser pits with a transmission electron microscope (TEM), the results show that the subsurface structures can be divided into three classes and that npFe can be easily found in Fe-bearing minerals. These differences in impact characteristics will help determine the source material of npFe and infer the type of micrometeorite impactors. During micrometeorite bombardment, in the mare regions, the npFe are probably produced simultaneously from lunar basalt and micrometeorites with iron-rich minerals, while the npFe in the highlands regions mainly come from micrometeorites.

Accurately and quickly obtaining the three-dimensional (3D) shape information of objects has become increasingly important in various scientific fields. However, simultaneously achieving the high-resolution and high-speed 3D shape measurement of unknown objects remains challenging in practice. In this Letter, we propose a novel variant shifting-phase method for 3D optical measurement. Based on a digital fringe projection system, the method performs a point-wise high-resolution measurement of objects by projecting only four intensity-coded patterns. We can retrieve the wrapped phases and their corresponding fringe orders simultaneously from these four patterns, and do not require any pre-acquired information of the object. The experimental results successfully demonstrate the effectiveness of the easy-to-operate method.

Silicon-based anode materials enable the development of commercial lithium-ion batteries (LIBs) with higher gravimetric energy densities than are currently available. However, the inherently low electronic and ionic conductivity as well as large volume expansion upon lithiation of Si hinder their use in practical applications. Here we report a cation-disordered CuSi2P3 material, synthesized using high-energy ball milling, that shows improved stability, larger capacity, and higher ionic and electronic conductivity than pure Si. When used as an anode for LIBs, CuSi2P3 demonstrates a high reversible capacity of 2069 mA h g−1 with an initial Coulombic efficiency of 91% and a suitable working potential of 0.5 V (vs. Li+/Li). Further, after a two-step ball milling of CuSi2P3 with graphite, a yolk-shell structured carbon-coated CuSi2P3@graphene nanocomposite is formed that shows enhanced long-term cycling stability (1394 mA h g−1 after 1500 cycles at 2 A g−1; 1804 mA h g−1 after 500 cycles at 200 mA g−1) and rate capability (530 mA h g−1 at 50 A g−1), surpassing those for other Cu-Si, Cu-P, and Si-P compounds or single-component Si- and P-based composites. When coupled with a LiNi0.5Co0.2Mn0.3O2 (NCM) cathode in a full cell, the NCM//CuSi2P3 @graphene battery exhibits a high capacity of 140 mA h g−1 after 200 cycles, demonstrating the potential of CuSi2P3 anodes for the next-generation high-performance LIBs.

Carre algorithm is a classic phase shifting measurement method due to its advantage in resisting the error caused by inaccurate phase step. The conventional Carre algorithm only calculates the wrapped phase, so multiple frequencies are used to unwrap the phase so as to obtain the absolute phase, which increases the number of patterns and decreases the measuring speed. We propose a high-accuracy and 4-pattern phase retrieval method based on Carre algorithm. The phase step in Carre algorithm is encoded as a linear variable. With the linear phase step, we obtain both the wrapped phase and absolute phase simultaneously from only 4 patterns. The proposed method is non-sensitive to the errors in phase step, the same as the conventional Carre algorithm. In addition, because only 4 patterns are required for obtaining the wrapped phase and absolute phase, the proposed method is practical in high-speed 3D measurement. Experimental results demonstrate its performance in high accuracy (absolute accuracy is higher than 0.02 mm and relative accuracy is higher than 0.03%), efficiency (requires only 4 patterns) and robustness.

Diamond is a very promising material with exceptional properties for many high value-added applications especially due to the incorporation of impurities. As one of the most important impurities, nitrogen is widely found in natural and synthetic diamonds, and the control of nitrogen-related defects in diamond is definitely at the spotlight for its potentials in room temperature quantum applications. Since chemical vapor deposition (CVD) is one of the most promising techniques for diamond doping and realization of defect control, it is thus crucial to investigate the nitrogen impurities in as-grown CVD diamond. In this work, single-crystal diamonds were grown with different nitrogen concentration and the evolution of defects, morphologies and fundamental growth characteristics of the CVD diamond films was explored by various modern analysis and detection methods. It could be concluded that the introduction of nitrogen could result in an evident increase in supersaturation of the growth radicals at the growth interface, which would eventually distinctly promote the (100)-oriented diamond growth. In consequence, single-crystal diamonds of high crystalline quality and few carbonaceous impurities could be achieved at high growth rates with appropriate amounts of nitrogen addition. As the nitrogen concentration increased, the structure and content of the defects would evolve as well with the domination of point defects, probably leading to lattice deformation in the as-grown diamond films. The surface morphologies of the nitrogen-doped CVD diamond films could also be distinctly altered with the compromise between the development of step bunching process and the occurrence of two-dimensional growth, which would eventually lead to variations of the surface roughness and uniformity of the as-grown diamond films.

Fringe projection profilometry (FPP) has been extensively used to measure three-dimensional (3D) shape in recent years. Generally, high-frequency fringe patterns ensure high accuracy, while fewer patterns mean higher measuring speed in FPP. However, simultaneously meeting the high-frequency and few-patterns without any constraints are still big challenges, because several additional unwrapping patterns are needed to unwrap the high-frequency patterns. We propose a novel high-accuracy high-speed unconstrained method to obtain the 3D shape by projecting only four fringe patterns. The period of the fringe patterns in the proposed method reaches 70. The high frequency ensures the high measuring accuracy. Besides, only one additional pattern is used to unwrap the high-frequency patterns, ensuring the high measuring speed. This method calculates the absolute phase pixel by pixel independently without any pre-work or constraints, which is suitable for complex and isolated objects. The experimental results verify the high-speed and high-accuracy performance of our method.

In this paper, the Hard X-ray Modulation Telescope mission is introduced. Its primary objective is to perform the hard X-ray all sky survey of high resolution and high sensitivity. The expected angular resolution and position accuracy of the satellite are better than 10 ′ and 2 ′ , respectively. The preliminary mission design is analyzed. And a new attitude subsystem scheme is presented to meet the high precision demand of attitude determination. A conclusion is drawn that the mission design is feasible. The possible launch of it will significantly advance the astrophysical study.