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The construction of multi-component composites has become an attractive strategy for high-performance microwave absorption through balancing the magnetic and dielectric loss. However, the influences of different components on absorption performance are ambiguous, which has inevitably hampered the widespread applications of microwave absorbents. Herein, we rationally designed the multi-component absorbers of N-doped carbon composited with Fe/Fe3C nanoparticles, and systematically investigate the impacts of Fe/Fe3C nanoparticles and Fe-Nx moieties on the microwave-absorbing capacities. It is found that the coexisitence of Fe/Fe3C and Fe-Nx is indispensable to realize the strong microwave absorption ability by simultaneously enhancing the dielectric and magnetic loss in the frequency range of 2-18 GHz. As expected, our optimal absorber dispersed in paraffin with a filler loading of 15 wt% exhibits the minimum reflection loss (RLmin) value of -49 dB and the maximum effective absorption bandwidth (BWeff) value of 4.2 GHz at a low thickness. Our work specifies the importance and influence of the coexistence between the Fe-Nx configurations and Fe/Fe3C nanoparticles in the carbon-based composites for the superior microwave absorption and inspires the future fabrication of extraordinary materials in the electromagnetic field.

A novel lattice hydrodynamic model is proposed by integrating the cooperative deviation of density and optimal flux under vehicle to X (V2X) environment. According to the theoretical analysis, the stability conditions and the mKdV equations affected by the cooperative deviation of traffic information are explored. And the density wave, hysteresis loop and energy consumption of the traffic flow have been investigated via numerical simulation. The results indicate that the cooperative deviation of density and optimal flux can effectively alleviate the traffic congestion. More importantly, our new consideration can reduce fuel consumption and exhaust emission under the V2X environment.

We measure the significance of thermally pulsing asymptotic giant branch (TP-AGB) stars via the spectral energy distributions (SEDs) of a sample of post-starburst (PSB) galaxies at z = 0.2–0.7. Using ground- and space-based photometry from the 3D-HST catalog, as well as associated near-infrared (NIR) Hubble Space Telescope (HST) slitless grism spectroscopy, we evaluate the importance of TP-AGB stars in the SEDs of 177 PSB galaxies by fitting simple stellar populations with different levels of TP-AGB contributions. The grism spectra, despite their low resolution of R ∼ 100, enable the detection of molecular features specific to TP-AGB stars and thus improve constraints on their contribution. A majority (∼70%) of galaxies in the PSB sample show features indicative of TP-AGB stars, while the remainder does not and they are well fit by Bruzual & Charlot TP-AGB light models. Stacked spectra of sources classified to be the best fit by TP-AGB heavy/mild models reveal strong detections of NIR molecular features associated with TP-AGB stars. Additionally, we observe a tentative trend with redshift where more TP-AGB heavy galaxies are observed in the higher redshift PSB galaxy population. Finally, neglecting the contribution of TP-AGB stars can yield an over-prediction of stellar masses measured in the K-band ranging from 0.13–0.23 dex.

As the core device of power electronic equipment, IGBT (Insulated Gate Bipolar Transistor) is related to the reliability of the system, so its online health monitoring is particularly important. Due to the large amount of data and high sampling rate for IGBT online health monitoring, data transmission has become a major problem, the method of effectively reconstructing the original signal has become one of the current research hotspots. Based on the theory of compressed sensing, the acquisition of IGBT gate waveforms is studied in this paper. First, the theoretical principle of compressed sensing is expounded and analyzed, and the evaluation criteria for signal reconstruction performance are given. Then, from the theory and simulation, the sparseness of IGBT gate drive signals under different sparse bases and different measurement matrices are discussed and analyzed. Next, aiming at the shortcomings of the stagewise weak orthogonal matching pursuit algorithm, a SWOMP algorithm based on the backtracking strategy of different Sigmoid functions is proposed. Simulation and experimental results show that the improved SWOMP4 algorithm has the best reconstruction effect. Finally, the SWOMP4 algorithm is applied to the process of IGBT gate drive signal reconstruction. This paper mainly collects and reconstructs the IGBT gate drive signal through the improved SWOMP4 algorithm. The designed algorithm has high reconstruction accuracy and can be used in the IGBT module online health status system.

Diffuse interstellar bands (DIBs) have always been a mysterious existence in astronomical research. In this work, we provide more DIB samples to slightly uncover this mystery. With the LAMOST medium-resolution survey (MRS) spectra, we detected three DIBs λ6379, λ6614, and λ6660, obviously superimposed on the spectra of 11,003 stars. These spectra cover spectral types from O to K, which can provide a large number of candidates for further research on DIBs. The sample shows a clear positive correlation between the strength of DIBs and extinction, which agrees with the result in the literature. In addition, there exist two peaks in each of the velocity distribution of these three DIBs, and the velocity differences between two peaks of each pair are consistent. The reason for the two velocity components is due to the Galactic rotation.

Agricultural picking robots have ushered in a good development period, and the research on the related technologies is becoming more and more practical. Based on this, this paper designs a crop identification and localization method based on binocular vision and deep learning supplemented by FPGA hardware platform. This paper firstly introduces the necessity of the technology for recognition and localization, then introduces the theoretical knowledge of camera calibration, stereo matching, and convolutional neural networks, etc. Finally, the implementation of relevant algorithms and the system architecture model are carried out. The method designed in this paper can provide technical support for agricultural picking robots, which can contribute to the development of picking robots.

This work is to retrieve emission-line spectra from the “Unknown” data set in LAMOST DR7 V1.2, most of which are low signal-to-noise ratios spectra. In the work, we perform emission line search and redshift calculations on the Unknown data set to get possible emission line galaxy spectra. Taking the galaxy spectra released by LAMOST as templates, the Product Quantization (PQ) based approximate nearest neighbor (ANN) search is used to retrieve the nearest neighbors of each spectrum. We keep the spectra for which the calculated redshift and the published redshift of the template meet the threshold, and 16,188 spectra with emission lines are obtained from the LAMOST DR7 Unknown data set. After visual inspection of spectra 10,266 spectra are left, in which 5828 spectra are identified as emission-line galaxies, 1782 spectra show ionization nebula features, and other 2656 are not clearly classified. Among 5828 spectra, 5720 can be found in Strasbourg astronomical Data Center catalog, Sloan Digital Sky Survey catalog, or NASA/IPAC Extragalactic Database catalog. The 108 spectra (corresponding to 106 unique coordinates of R.A. and decl.) which have no record in these three databases are new discoveries; for the 1782 spectra showing ionization nebula features, most of them have radial velocities less than 150 kilometers per second. We check them with the latest version of WISE H ii catalog V2.0 (short for HIICat V2) and 985 out of the 1782 spectra belong to 72 H ii regions. Of these H ii regions, 43 were previously identified while the other 29 are newly identified in this work including 797 newly observed spectra. Besides, there are still 2656 spectra that cannot be clearly classified although they have obvious emission lines and with small redshift. Finally, 106 new emission-line galaxies and 29 new Galactic H ii regions are identified, and we conclude that the ANN method sped up by the PQ algorithm is efficient in solving the problem of pairing spectra with massive data set to figure out their classes. We present our result at the link http://paperdata.china-vo.org/LY_paper/Work2/pressWork2_last.zip.

The working mechanism of a half-bridge SiC MOSFETs two chips parallel module is studied. Its parasitic inductance of the power module is simulated by using the Ansoft Q3D Extractor software, and its heat transfer mechanism is simulated using the finite element software ANSYS software. Aiming at reducing the parasitic inductance, a new topology of power chips inside the module is designed, which places the chips that are in the same working circuit loop in close vicinity to reduce the whole circuit length and area. Meanwhile, the thermal characteristics are also analyzed. Considering the factors of parasitic inductance and heat dissipation, the optimal module design scheme is finally determined.

In-memory computing is highly expected to break the von Neumann bottleneck and memory wall. Memristor with inherent nonvolatile property is considered to be a strong candidate to execute this new computing paradigm. In this work, we have presented a reconfigurable nonvolatile logic method based on one-transistor-two-memristor device structure, inhibiting the sneak path in the large-scale crossbar array. By merely adjusting the applied voltage signals, all 16 binary Boolean logic functions can be achieved in a single cell. More complex computing tasks including one-bit parallel full adder and set–reset latch have also been realized with optimization, showing simple operation process, high flexibility, and low computational complexity. The circuit verification based on cadence PSpice simulation is also provided, proving the feasibility of the proposed design. The work in this paper is intended to make progress in constructing architectures for in-memory computing paradigm.

According to the analysis on the working principle of the load-sensing hydraulic system with multi-way valve and constant-difference relief pressure-compensated valve in the load-sensing circuit, it is concluded that there are two working conditions during the operation of the system, load-sensing condition and constant pressure supply condition. Without considering the effect of balance valves, the load boundaries of the forward and backward motion of two conditions were derived, as well as the whole load boundary. The selection principle of balance valves was studied and analyzed to expand the load boundaries. The above conclusions can be applied to this type of load-sensing hydraulic system with any valve-controlled cylinder structure and also provide the theoretical guidance for the design and apply of the system.

In view of the shortage of models of practical installation and teaching AIDS in the teaching and training of traditional naval ship diesel engines, the 3D printing technology is integrated with the educational concept of this course, and a multi-functional diesel engine teaching AIDS model suitable for classroom teaching is designed and manufactured, and its design method and process are expounded. A set of models of diesel engine teaching AIDS are designed and manufactured by using this method and applied in classroom teaching. The teaching effect is good, the learners’ enthusiasm is stimulated, and the teaching and training quality is improved.

We report the detection of a large sample of high-$\alpha$-metal-rich stars on the low giant branch with $2.60.2$ than the comparison group. These properties strongly indicate its connection with the outer bar/bulge region at $R=3-5$ kpc. A tentative interpretation of this special group is that its stars were formed in the X-shaped bar/bulge region, close to its corotation radius, where radial migration is the most intense, and brings them to present locations at 9 kpc and beyond. Low eccentricities and slightly outward radial excursions of its stars are consistent with this scenario. Its kinematics (cold) and chemistry ($[\alpha/Fe]$ $\sim 0.1$) further support the formation of the instability-driven X-shaped bar/bulge from the thin disk., Comment: 13 pages, 8 figures, accepted for publication in Research in Astronomy and Astrophysics

Reconciling economic development with ecological environmental protection has always been a hot issue of the whole society. However, existing studies only consider the impact of per capita income on environmental pollution, while ignoring the existence of income gap and its possible impact on environmental pollution. Therefore, the paper focuses on the specific analysis of the relationship between income gap and environmental pollution in 48 countries and revising the EKC theory. The empirical analysis results show that: there is an M-shaped relationship between the income gap and the per-capita carbon emissions, and the three turning points are 0.27, 0.36 and 0.52; there is an N-shaped relationship between the per-capita income and the per-capita carbon emissions, and the two turning points are 5218.65 and 13766.50 international dollars; the per-capita carbon emissions increases significantly as the per-capita energy consumption increases; and there is a significant negative relationship between the urbanization rate and the per-capita carbon emissions, which provide theoretical reference for the government to formulate corresponding policy measures.

The LAMOST II survey began in the fall of 2018, and LAMOST formally released the obtained medium-resolution spectra (MRS) as well as catalogs of stellar parameters and radial velocities (RV) derived from the MRS in the seventh LAMOST data release (DR7). Compared with the RVs and parameters from high-resolution SDSS14/APOGEE spectra, nearly no RV discrepancy was found, with only dispersion around one km s−1. The T eff of MRS was 27.79 K systematically lower than that of APOGEE, and the 1σ difference was approximately 60.40 K. For metallicity, the [Fe/H] of the MRS was 0.11 dex poorer than that of APOGEE, with a dispersion of 0.07 dex. More apparently, the offset of log g was 0.14 dex, and the scatter was 0.23 dex. The gravities of APOGEE have been corrected through seismological data. Similarly, in this study, we tried to calibrate LAMOST MRS log g with the Kepler data for red clump stars and red giant branch stars based on two fitted calibration relations. In addition, we found log g of a small fraction late-K type giants mistakenly measured as dwarfs, and vice versa, on the HR diagram generated with LAMOST T eff and Gaia absolute magnitudes. This was because the MRS parameters were measured from blue band spectra only. The measurements of log g for late-K stars can be significantly improved by adding red spectra.

In the process of successful establishment and development of service ecosystem organization, manufacturing companies not only pay attention to their own resources, business models and competitive advantages, but also pay attention to the positioning in the manufacturing service ecosystem and the symbiosis with other members of the system to achieve complementarity and symbiotic development of resources among members. Based on this, we take the manufacturing service ecosystem in the transformation and upgrading of the manufacturing enterprises in China as the research object, and comprehensively uses the theory of evolutionary game and ecosystem to study the symbiotic evolutionary stability of the manufacturing service ecosystem. Through simulation, we find that integrator is more sensitive to the change of rights than supplier. Our conclusions have certain reference for manufacturing companies to improve the collaborative operation efficiency of manufacturing service ecosystem.

Spoken language understanding (SLU) in multi-turn task-oriented dialogue systems usually needs to take historical contextual information into account. To achieve this, current approaches encode dialogue utterances with contextual information to improve the accuracy of slot filling and intent detection. However, this kind of approach ignores the different influences of contextual information on dialogue utterances. Some utterances with independent context will be misunderstood due to the addition of noisy contextual information. In this paper, we propose a Dual Semantics model(CSD) that is based on dual semantics. Each dialogue utterance is encoded based on independent semantics and contextual semantics, where the contributions of these two semantic information are dynamically decided. A large number of experiments on two datasets verify the effectiveness of our approach. Specifically, the accuracy of slot filling at the KVRET dataset increases by 3.3% compared to the baseline model. A dataset of psychological service appointments(PSA), is further collected for the verification of our approach. Compared with existing methods, the accuracy is improved by 4.9% on this dataset.

As to the hot research aspect of soil remediation, this review elaborated the progress in the application of nanomaterials in heavy metals and organics-contaminated soil remediation, and discussed the ecological safety of nanomaterials usage as well. The mechanism of nanomaterial-based soil remediation mainly includes adsorption, complexation, transformation, etc. The activities of nanomaterials could be enhanced by modification methods. Iron based nanoparticles such as zero-valent iron (nZVI), iron oxide and iron sulphide showed promising application prospect but also possible toxicity to soil ecosystem. However, biologically synthesized nanomaterials are more effective and safer, which has been demonstrated in many studies. Therefore, bio-nanomaterials which can not only meet the requirements of soil recovery, but also contribute to soil fertility is urgently needed.

Noble metals nanoparticles (NMNPs) due to unique physical and chemical properties have attracted intense scientific interest for wide applications. Nanosphere lithography demonstrates a feasible strategy to achieve various metal nanostructures. In this paper, ZnO array is fabricated by magnetron sputtering method based on self-assemble polystyrene spheres (PSs) array. The thermal decomposition is used to achieve ZnO shell arrays by removing polystyrene spheres (PSs). The size of ZnO shell arrays can be controlled by changing the size of PS spheres. Disordered Au nanoballs coated on ZnO shell array are fabricated by electron beam deposition and the thermal decomposition to enhance optical properties of ZnO shell array. Optical properties, Morphology and chemical composition of Au nanoballs coated on ZnO shell array are analyzed by UV–vis Spectrophotometer, SEM and XRD. Based on localized surface plasmon resonance (LSPR) of the metal nanoparticles, the optical properties of ZnO shell array are enhanced by disordered Au nanoballs. Hence, it can be potentially applied in related optoelectronic devices.

Carbon stars are excellent kinematic tracers of galaxies and can serve as a viable standard candle, so it is worthwhile to automatically search for them in a large amount of spectra. In this paper, we apply the efficient manifold ranking algorithm to search for carbon stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) pilot survey, whose performance and robustness are verified comprehensively with four test experiments. Using this algorithm, we find a total of 183 carbon stars, and 158 of them are new findings. According to different spectral features, our carbon stars are classified as 58 C-H stars, 11 C-H star candidates, 56 C-R stars, ten C-R star candidates, 30 C-N stars, three C-N star candidates, and four C-J stars. There are also ten objects which have no spectral type because of low spectral quality, and a composite spectrum consisting of a white dwarf and a carbon star. Applying the support vector machine algorithm, we obtain the linear optimum classification plane in the J - H versus H - K-s color diagram which can be used to distinguish C-H from C-N stars with their J - H and H - K-s colors. In addition, we identify 18 dwarf carbon stars with their relatively high proper motions, and find three carbon stars with FUV detections likely have optical invisible companions by cross matching with data from the Galaxy Evolution Explorer. In the end, we detect four variable carbon stars with the Northern Sky Variability Survey, the Catalina Sky Survey and the LINEAR variability databases. According to their periods and amplitudes derived by fitting light curves with a sinusoidal function, three of them are likely semiregular variable stars and one is likely a Mira variable star.

Hypervelocity stars are believed to be ejected out from the Galactic center through dynamical interactions between (binary) stars and the central supermassive black hole(s). In this paper, we report 19 low mass F/G/K type hypervelocity star candidates from over one million stars found in the first data release of the LAMOST regular survey. We determine the unbound probability for each candidate using a Monte-Carlo simulation by assuming a non-Gaussian proper-motion error distribution, and Gaussian heliocentric distance and radial velocity error distributions. The simulation results show that all the candidates have unbound possibilities over 50% as expected, and one of them may even exceed escape velocity with over 90% probability. In addition, we compare the metallicities of our candidates with the metallicity distribution functions of the Galactic bulge, disk, halo and globular clusters, and conclude that the Galactic bulge or disk is likely the birth place for our candidates.

A sample of 70 E+A galaxies is selected from 37 206 galaxies in the second data release of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). This sample is selected according to the criteria for E+A galaxies defined by Goto, and each of these objects is further visually identified. In this sample, most objects are low redshift E+A galaxies with z < 0.25 , and are located in an area of the sky with high Galactic latitude and magnitude from 14 to 18 mag in the g , r and i b ands. A stellar population analysis of the whole sample indicates that the E+A galaxies are characterized by both young and old stellar populations (SPs), and the metal rich SPs have relatively higher contributions than the metal-poor ones. Additionally, a morphological classification of these objects is performed based on images taken from the Sloan Digital Sky Survey .

We have compared stellar parameters, including temperature, gravity and metallicity, for common stars in the LAMOST DR2 and SDSS DR12/APOGEE datasets. It is found that the LAMOST dataset provides a more well-defined red clump feature than the APOGEE dataset in the T eff versus log g diagram. With this advantage, we have separated red clump stars from red giant stars, and attempt to establish calibrations between the two datasets for the two groups of stars. The results show that there is a good consistency in temperature with a calibration close to the one-to-one line, and we can establish a satisfactory metallicity calibration of [Fe/H] APOGEE = 1.18[Fe/H] LAMOST + 0.11 with a scatter of ~ 0.08 dex for both the red clump and red giant branch samples. For gravity, there is no correlation for red clump stars between the two datasets, and scatters around the calibrations of red giant stars are substantial. We found two main sources of scatter in log g for red giant stars. One is a group of stars with 0.00253 × T eff − 8.67 −1 and log g APOGEE = 0.000874× T eff,LAMOST +0.588×log g LAMOST −3.117 (σ = 0.167) for [Fe/H] < −1. The calibrations are valid for stars with T eff = 3800 − 5400 K and log g = 0 − 3.8 dex, and are useful in work aiming to combine the LAMOST and APOGEE datasets in a future study. In addition, we find that an SVM method based on asteroseismic log g is a good way to greatly improve the accuracy of gravity for these two regions, at least in the LAMOST dataset.

We report the discovery of 64 luminous infrared galaxies, based on new observations of 20 square degrees from the LAMOST Complete Spectroscopic Survey of Pointing Area at the Southern Galactic Cap and the WISE 22 μ m catalog from the AllWISE Data Release. Half of them are classified as late-type spirals and the others are classified as peculiar/compact galaxies. The peculiar/compact galaxies tend to exhibit higher luminosities and lower stellar masses. We also separate AGNs from HII galaxies in a simple way by examining LAMOST spectra. Those cases show that host AGNs are easily distinguished from others in the mid-infrared color-color diagrams.

We present a spectroscopic catalog of 93 619 M dwarfs from the first data release of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) general survey. During sample selection, M giant contamination was eliminated using 2MASS photometry and CaH/TiO molecular indices. For each spectrum, the spectral subtype and values are provided including radial velocity, Hα equivalent width, a series of prominent molecular band indices, and the metal–sensitive parameter ζ, as well as distances and the space motions for high S/N objects. In addition, Hα emission lines are measured to examine the magnetic activity properties of M dwarfs and 7179 active ones are found. In particular, a subsample with significant variation in magnetic activity is revealed through observations from different epochs. Finally, statistical analysis for this sample is performed, including the metallicity classification, the distribution of molecular band indices and their errors.

We quantify and correct systematic errors in PPMXL proper motions using extragalactic sources from the first two LAMOST data releases and the Veron-Cetty & Veron Catalog of Quasars. Although the majority of the sources are from the Veron catalog, LAMOST makes important contributions in regions that are not well-sampled by previous catalogs, particularly at low Galactic latitudes and in the south Galactic cap. We show that quasars in PPMXL have measureable and significant proper motions, which reflect the systematic zero-point offsets present in the catalog. We confirm the global proper motion shifts seen by Wu, Ma, & Zhou (2011), and additionally find smaller-scale fluctuations of the QSO-derived corrections to an absolute frame. We average the proper motions of 158,106 extragalactic objects in bins of 3x3 degrees and present a table of proper motion corrections., Accepted for publication in RAA; 12 pages, 6 figures (Fig. 1 at reduced resolution); full table of corrections available in online journal, with arxiv ancillary files (as ASCII table), or by request

We report on the first investigation into kinematics and chromospheric activity of M dwarfs from the Guo Shou Jing Telescope (also called the Large Sky Area Multi-Object Fiber Spectroscopic Telescope – LAMOST) data release one (DR1). The sample comprises 71 304 M dwarfs. Their fundamental parameters such as spectral types, radial velocities, important molecular band indices and magnetic activities are measured. Their distances are determined by a spectroscopic parallax relation. Space motion ( U , V , W ) and Galactocentric cylindrical coordinates ( R, θ, Z ) for the M dwarfs are also computed. We examine velocity dispersion as a function of height from the Galactic plane and find that all three components of velocity dispersion increase with height as measured with respect to the Galactic plane. The investigation into chromospheric activities along the height from the Galactic plane confirms that M dwarfs closer to the Galactic plane are more likely to be active. We take a pure kinematical approach to select thin disk stars and thick disk stars from our sample, then to investigate the differences in properties between these two populations. Our analysis is in excellent agreement with previous studies and leads to a better understanding of the structure of the Galactic disk.