53 research outputs found

    Nematic crossover in BaFe2_2As2_2 under uniaxial stress

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    Raman scattering can detect spontaneous point-group symmetry breaking without resorting to single-domain samples. Here we use this technique to study BaFe2As2\mathrm{BaFe_2As_2}, the parent compound of the "122" Fe-based superconductors. We show that an applied compression along the Fe-Fe direction, which is commonly used to produce untwinned orthorhombic samples, changes the structural phase transition at temperature TsT_{\mathrm{s}} into a crossover that spans a considerable temperature range above TsT_{\mathrm{s}}. Even in crystals that are not subject to any applied force, a distribution of substantial residual stress remains, which may explain phenomena that are seemingly indicative of symmetry breaking above TsT_{\mathrm{s}}. Our results are consistent with an onset of spontaneous nematicity only below TsT_{\mathrm{s}}.Comment: 4 pages, 4 figure

    OmniObject3D: Large-Vocabulary 3D Object Dataset for Realistic Perception, Reconstruction and Generation

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    Recent advances in modeling 3D objects mostly rely on synthetic datasets due to the lack of large-scale realscanned 3D databases. To facilitate the development of 3D perception, reconstruction, and generation in the real world, we propose OmniObject3D, a large vocabulary 3D object dataset with massive high-quality real-scanned 3D objects. OmniObject3D has several appealing properties: 1) Large Vocabulary: It comprises 6,000 scanned objects in 190 daily categories, sharing common classes with popular 2D datasets (e.g., ImageNet and LVIS), benefiting the pursuit of generalizable 3D representations. 2) Rich Annotations: Each 3D object is captured with both 2D and 3D sensors, providing textured meshes, point clouds, multiview rendered images, and multiple real-captured videos. 3) Realistic Scans: The professional scanners support highquality object scans with precise shapes and realistic appearances. With the vast exploration space offered by OmniObject3D, we carefully set up four evaluation tracks: a) robust 3D perception, b) novel-view synthesis, c) neural surface reconstruction, and d) 3D object generation. Extensive studies are performed on these four benchmarks, revealing new observations, challenges, and opportunities for future research in realistic 3D vision.Comment: Project page: https://omniobject3d.github.io

    Temperature-independent thermal radiation

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    Thermal emission is the process by which all objects at non-zero temperatures emit light, and is well-described by the classic Planck, Kirchhoff, and Stefan-Boltzmann laws. For most solids, the thermally emitted power increases monotonically with temperature in a one-to-one relationship that enables applications such as infrared imaging and non-contact thermometry. Here, we demonstrate ultrathin thermal emitters that violate this one-to-one relationship via the use of samarium nickel oxide (SmNiO3), a strongly correlated quantum material that undergoes a fully reversible, temperature-driven solid-state phase transition. The smooth and hysteresis-free nature of this unique insulator-to-metal (IMT) phase transition allows us to engineer the temperature dependence of emissivity to precisely cancel out the intrinsic blackbody profile described by the Stefan-Boltzmann law, for both heating and cooling. Our design results in temperature-independent thermally emitted power within the long-wave atmospheric transparency window (wavelengths of 8 - 14 um), across a broad temperature range of ~30 {\deg}C, centered around ~120 {\deg}C. The ability to decouple temperature and thermal emission opens a new gateway for controlling the visibility of objects to infrared cameras and, more broadly, new opportunities for quantum materials in controlling heat transfer.Comment: Main text and supplementar

    Alcohol consumption, DNA methylation and colorectal cancer risk:Results from pooled cohort studies and Mendelian randomization analysis

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    Alcohol consumption is thought to be one of the modifiable risk factors for colorectal cancer (CRC). However, the causality and mechanisms by which alcohol exerts its carcinogenic effect are unclear. We evaluated the association between alcohol consumption and CRC risk by analyzing data from 32 cohort studies and conducted two-sample Mendelian randomization (MR) analysis to examine for casual relationship. To explore the effect of alcohol related DNA methylation on CRC risk, we performed an epigenetic MR analysis with data from an epigenome-wide association study (EWAS). We additionally performed gene-alcohol interaction analysis nested in the UK Biobank to assess effect modification between alcohol consumption and susceptibility genes. We discovered distinct effects of alcohol on CRC incidence and mortality from the meta-analyses, and genetic predisposition to alcohol drinking was causally associated with an increased CRC risk (OR = 1.79, 95% CI: 1.23-2.61) using two-sample MR approaches. In epigenetic MR analysis, two alcohol-related CpG sites (cg05593667 and cg10045354 mapped to COLCA1/COLCA2 gene) were identified causally associated with an increased CRC risk (P < 8.20 × 10-4 ). Gene-alcohol interaction analysis revealed that carriage of the risk allele of the eQTL (rs3087967) and mQTL (rs11213823) polymorphism of COLCA1/COLCA2 would interact with alcohol consumption to increase CRC risk (PInteraction  = .027 and PInteraction  = .016). Our study provides comprehensive evidence to elucidate the role of alcohol in CRC and highlights that the pathogenic effect of alcohol on CRC could be partly attributed to DNA methylation by regulating the expression of COLCA1/COLCA2 gene

    Dual‐channel pre‐regulator structure for the bandgaps in high step‐down DC‐DC converters

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    Abstract High step‐down DC‐DC converters require a robust and low power pre‐regulated supply for bandgap reference. This paper proposes a structure that comprised of two current paths to achieve energy efficient pre‐regulation under high and low input voltage conditions. The design eliminated large size resistors for current limiting which is usually required for high input supplies. The presented pre‐regulator structure combined with the bandgap circuit was realized with the TSMC 180‐nm BCD process. The measured results show the proposed structure has a wide input voltage range of 3.5–45 V, a temperature coefficient of 5.63 ppm/°C and typical average current consumption of 1.1 μA

    Study on the Influence of Farmer Social Capital on Cooperative Supply Willingness of Agricultural Disaster Reduction Public Goods——Based on the Investigation on 515 Farmers

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    Based on social capital theory, related factors of three dimensions(structure dimension, cognition dimension and relation dimension)of farmer social capital are taken as independent variables, and famer’s willingness to cooperatively supply agricultural disaster reduction public goods is taken as dependent variable. Taking 515 farmers in 27 villages of Hubei Province as investigation objects, the influence of farmer social capital on cooperative supply willingness of agricultural disaster reduction public goods is explored by Logistic regression model. Research results show that social solidarity, common value concept, social trust and reciprocal content have positive impact on farmer’s willingness of cooperative supply, while annual household income, number of agricultural disaster reduction public goods and social network have negative impact on farmer’s willingness of cooperative supply

    Study on the Effect of Fracturing Pump Start and Stop on Tubing Fluid-Structure Interaction Vibration in HPHT Wells via MOC

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    The processes of HTHP well fracturing, oil drive, and gas recovery are accompanied by the non-stationary flow of medium in the tubing, which may lead to periodic vibration and cause the failure and fatigue of the tubing, thread leakage, and bending deformation. In this paper, a fluid&ndash;structure interaction model with 4-equation was established, which considered the unsteady flow of fluid and the motion state of tubing during the periodic injection, pump start, and shutdown of fluid in the tubing. Further, the discrete solution of MOC was used to obtain the variation of fluid flow rate and pressure, tubing vibration rate, frequency, and additional stress with time. The resonance construction parameters corresponding to different tubing diameters were analyzed by discussing the effects of different start and shutdown times as well as pressure on the tubing vibration parameters. The results show that under the periodic injection condition, increasing the tubing diameter or start inside pressure would lead to a sharp increase in the axial additional stress of the tubing generated by fluid&ndash;structure interaction, which is not conducive to the safety protection of the tubing. When the pump was shutdown, excessively short operation times and high pressure in the tubing would lead to excessive transient loads in addition to resonance, which would cause damage to the pipeline. Finally, corresponding to the above analysis results, this paper proposes the optimal injection parameters to avoid the generation of resonance, which provides a theoretical basis and reference range for the safe service conditions of the tubing

    Study on the Effect of Fracturing Pump Start and Stop on Tubing Fluid-Structure Interaction Vibration in HPHT Wells via MOC

    No full text
    The processes of HTHP well fracturing, oil drive, and gas recovery are accompanied by the non-stationary flow of medium in the tubing, which may lead to periodic vibration and cause the failure and fatigue of the tubing, thread leakage, and bending deformation. In this paper, a fluid–structure interaction model with 4-equation was established, which considered the unsteady flow of fluid and the motion state of tubing during the periodic injection, pump start, and shutdown of fluid in the tubing. Further, the discrete solution of MOC was used to obtain the variation of fluid flow rate and pressure, tubing vibration rate, frequency, and additional stress with time. The resonance construction parameters corresponding to different tubing diameters were analyzed by discussing the effects of different start and shutdown times as well as pressure on the tubing vibration parameters. The results show that under the periodic injection condition, increasing the tubing diameter or start inside pressure would lead to a sharp increase in the axial additional stress of the tubing generated by fluid–structure interaction, which is not conducive to the safety protection of the tubing. When the pump was shutdown, excessively short operation times and high pressure in the tubing would lead to excessive transient loads in addition to resonance, which would cause damage to the pipeline. Finally, corresponding to the above analysis results, this paper proposes the optimal injection parameters to avoid the generation of resonance, which provides a theoretical basis and reference range for the safe service conditions of the tubing

    A novel GRU-TCN network based Interactive Behavior Learning of multi-energy Microgrid under incomplete information

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    The interactive operation of multi-energy Microgrid (MEMG) in energy market is facing more and more incomplete information decision-making requirements due to the enhanced privacy of users, which brings great challenges to the participation flexibility of MEMG in demand response programs. Meanwhile, considering the uncertainty of the external MEMG unit combination, the randomness of the environmental meteorology, the interactive characteristics of the external MEMGs are complex and time-varying. To solve these problems, a novel GRU-TCN network based Interactive Behavior Learning method for MEMG interactive operation is proposed. The proposed Interactive Behavior Learning framework needs merely externally available input information and historical interaction power data to efficiently predict the interaction power, which protects the data privacy of users. Besides, the GRU-TCN network also leverages the strengths of Recurrent Neural Network and Convolutional Neural Networks while incorporating the self-attention mechanism. This combination enables the GRU-TCN network to effectively capture the relationship between interactive power and the available resources data beyond the MEMG. The example analysis and test are carried out on a typical MEMG system, and the case study turns out that the proposed GRU-TCN network has the capability to capture coupling mechanisms even in the presence of incomplete information and present more accurate prediction of multi-energy interactive data
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