(Ti_(60)Cr_(30)Nb_(10))_(100-x)Al_(x)轻质中熵合金的力学与腐蚀性能

研究轻质(Ti_(60)Cr_(30)Nb_(10))_(100-x)Al_(x)(x=0,5,7.5,10,摩尔分数,%)中熵合金在铸态和均匀化态下的显微组织、力学性能和腐蚀行为。结果表明,随着Al含量从0增加到10%(摩尔分数),铸态合金均由相同的相组成,即体心立方(BCC)相和少量TiCr2型Laves相组成。均匀化后,所有合金均由单相BCC组成。此外,(Ti_(60)Cr_(30)Nb_(10))_(95)A_(l5)中熵合金表现出在铸态和均匀态条件下最优异的力学性能,屈服强度分别约为1048 MPa和1017 MPa,同时保持超50%压缩应变。与TC4和铸态(Ti_(60)Cr_(30)Nb_(10))_(95)A_(l5)合金相比,均匀态(Ti_(60)Cr_(30)Nb_(10))_(95)A_(l5)合金表现出更优异的耐腐蚀性能,这主要归因于均匀的显微组织与化学成分。

细观初始孔隙缺陷对混凝土力学性能的影响

采用不同尺寸的EPS颗粒预制混凝土的初始孔隙率及初始孔径尺寸,系统开展4种初始孔隙率和5种初始孔径尺寸下混凝土的轴心抗压强度和弹性模量试验研究,并基于数值统计原理分析含初始缺陷混凝土力学性能的影响规律.结果表明:混凝土的轴心抗压强度和弹性模量降幅随初始孔隙率的增加呈近似线性上升趋势,混凝土的轴心抗压强度降幅随着初始孔径尺寸的增加呈近似对数上升趋势.同时考虑初始孔隙率和初始孔径尺寸的影响,混凝土在初始小孔径、高孔隙率下的损伤度低于其在初始大孔径、低孔隙率下的损伤度.相较初始孔径尺寸,初始孔隙率对混凝土轴心抗压强度和弹性模量的损伤更为显著.

增强小学数学教学逻辑性的关键问题探究

本文深入探讨了数学教学的逻辑性及其重要性,强调了数学教学应系统回答五个关键问题。首先,通过讲述故事、联系生活、互动游戏、动手实践和直面问题等策略有效引入新知识,明确“学什么”的问题;其次,通过阐明数学学习对未来生活和深入学习的必要性,解答“为什么学”的问题;在学习方法上,提倡独立思考、自由交流和研究体验,解决“怎样学”的问题;针对“学到什么”,关注学生表达学习结论、建构知识框架和学习效果评估的重要性;最后,强调数学学习的实际应用价值,包括基础性应用、多样化应用和创造性应用,解决“学了有什么用”的问题。

小学数学中量感培养的教学策略

《义务教育数学课程标准(2022年版)》新引入了“量感”核心素养,反映了对学生测量相关能力的重视,强调了量感在理解世界中的重要性。文章通过具体的案例分析,指出小学数学教师可以通过引领学生亲历度量实践活动,数学思考量感,通过估测活动增强量感的能力。这些策略促使学生通过体验、思考和应用,逐步深化对量感的理解,进而提升解决问题的能力。

Dietary Lipid Intervention in the Prevention of Brain Aging

As people live longer,the burden of aging-related brain diseases,especially dementia,is increasing.Brain aging increases the risk of cognitive impairment,which manifests as a progressive loss of neuron function caused by the impairment of synaptic plasticity via disrupting lipid homeostasis.Therefore,supplemental dietary lipids have the potential to prevent brain aging.This review summarizes the important roles of dietary lipids in brain function from both structure and mechanism perspectives.Epidemiological and animal studies have provided evidence of the functions of polyunsaturated fatty acids(PUFAs)in brain health.The results of interventions indicate that phospholipids—including phosphatidylcholine,phosphatidylserine,and plasmalogen—are efficient in alleviating cognitive impairment during aging,with plasmalogen exhibiting higher efficacy than phosphatidylserine.Plasmalogen is a recognized nutrient used in clinical trials due to its special vinyl ether bonds and abundance in the postsynaptic membrane of neurons.Future research should determine the dose-dependent effects of plasmalogen in alleviating brain-aging diseases and should develop extraction and storage procedures for its clinical application.

Source model of the 2018 M_(w)7.5 Papua New Guinea earthquake constrained by InSAR measurements: Insight into a blind rupture beneath the New Guinea Highlands

The Southern Highland Fold and Thrust Belt(SHFTB),the boundary of the Australian plate and the New Guinea Highland block,significantly contributes to the convergent deformation along the plate bound-ary.However,due to the lack of observation data,the detailed slip pattern of the SHFTB and the orogenic mechanism beneath the New Guinea Highlands remains controversial.On 25 February 2018,the M_(w)7.5 Papua New Guinea(PNG)earthquake struck the southeastern segment of the SHFTB.The detailed rupture characteristics of this event is significant for further clarifying the inter-seismic slip pattern along the SHFTB.Here,the coseismic deformation field of this earthquake was obtained using high-resolution ALOS-2 satellite images.We find that the 2018 M_(w)7.5 PNG earthquake ruptured a large-scaled fault(SHFTB)extending to the lower crust(deeper than 20 km)beneath the New Guinea Highlands,with a dip angle of 24°.The slips on the fault plane are equivalent to moment magnitudes of M_(w)7.51.Three major asperities with thrust-dominated slip of up to 3.94 m are detected on the fault plane.This finding implies that the slip pattern on the eastern segment of the SHFTB is dominated by thrust,rather than with significant sinistral movement,as previously reported.The tectonic deformation across the New Guinea Highlands is possibly concentrated on the large-scale fault SHFTB and primarily controls the intra-continental orogeny in the central Papua New Guinea.

Efficient concentration of trace analyte with ordered hotspot construction for a robust and sensitive SERS platform

Surface-enhanced Raman scattering(SERS)platform,which enables trace analyte detection,has important application prospects.By structuring/modifying the surface of the SERSsubstrate,analyte in highly diluted solutions can be concentrated into localized active areas for highly sensitive detection.However,subject to the difficulty of the fabrication process,itremains challenging to balance hot-spot construction and the concentration capacity of analyte simultaneously.Therefore,preparing SERS substrates with densely ordered hot spots andefficient concentration capacity is of great significance for highly sensitive detection.Herein,we propose an Ag and fluoroalkyl-modified hierarchical armour substrate(Ag/F-HA),which has a double-layer stacking design to combine analyte concentration with hotspot construction.The microarmour structure is fabricated by femtosecond-laser processing to serve as asuperhydrophobic and low-adhesive surface to concentrate analyte,while the anodic aluminium oxide(AAO)template creates a nanopillar array serving as dense and ordered hot spots.Under the synergistic action of hot spots and analyte concentration,Ag/F-HA achieves a detectionlimit down to 10^(-7)M doxorubicin(DOX)molecules with a RSD of 7.69%.Additionally,Ag/F-HA exhibits excellent robustness to resist external disturbances such as liquid splash or abrasion.Based on our strategy,SERS substrates with directional analyte concentrations are further explored by patterning microcone arrays with defects.This work opens a way to the realistic implementation of SERS in diverse scenarios.

A chromosome-level genome assembly for Chinese plum‘Wushancuili'reveals the molecular basis of its fruit color and susceptibility to rain-cracking

Chinese plum(Prunus salicina Lindl.)originates from China and makes a large contribution to the global production of plums.The P.salicina‘Wushancuili'has a green coloration and high fruit quality and is economically important in eliminating poverty and protecting ecology in the Yangtze River Three Gorges Reservoir.However,rain-induced cracking(rain-cracking,literally skin cracking caused by rain)is a limitation to‘Wushancuili'fruit production and causes severe losses.This study reported a high-quality‘Wushancuili'genome assembly consisting of a 302.17-Mb sequence with eight pseudo-chromosomes and a contig N50 of 23.59 Mb through the combination of Illumina sequencing,Pacific Biosciences HiFiⅢsequencing,and high-throughput chromosome conformation capture technology.A total of 25109 protein-coding genes are predicted and 54.17%of the genome is composed of repetitive sequences.‘Wushancuili'underwent a remarkable orthoselection during evolution.Gene identification revealed that loss-of-function in four core MYB10 genes results in the anthocyanin deficiency and absence of red color,revealing the green coloration due to the residual high chlorophyll in fruit skin.Besides,the occurrence of cracking is assumed to be closely associated with cell wall modification and frequently rain-induced pathogen enrichment through transcriptomic analysis.The loss of MYB10 genes might render fruit more susceptible to pathogen-mediated cracking by weakening the epidermal strength and reactive oxygen species(ROS)scavenging.Our findings provided fundamental knowledge regarding fruit coloration and rain-cracking and will facilitate genetic improvement and cultivation management in Chinese plums.

Slip rate and interseismic coupling along the Moxi-Shimian segment of the Xianshuihe fault, Eastern Qinghai-Xizang Plateau

On September 5,2022,the Luding M6.8 earthquake occurred in the Moxi-Shimian segment of the Xianshuihe fault,coinciding with the historical ruptured zone of the 1786 Moxi earthquake.Its seis-mogenic environment provides a foundation for comprehending the mechanism of the earthquake and its future hazard.In the Moxi-Shimian segment,we establish a series of near-field Global Navigation Satellite Systems(GNsS)stations to enhance the spatial resolution of observational data for the inversion of the interseismic kinematic parameters.In this study,with an elastic screw dislocation model con-strained by GNsS observations,the slip rate of the Moxi-Shimian segment is estimated to be 10.9±1.0 mm/yr,while the locking depth is 15.7±6.2 km.Additionally,we utilize a block-dislocation model to invert the interseismic fault coupling along the Kangding-Moxi-Shimian segment.The result indicates a gradual deepening of the locking depth along the section from Kangding to Shimian.The coseismic rupture of the 2022 event occurred within the high coupling regions in the Kangding-Moxi-Shimian segment,which indicates that the rupture kinematics in this event might be controlled by the interseismic deformation.The seismic moment accumulated within the ruptured zone of the Luding earthquake since 1786 ranges in[1.42-3.40]×10^(19) N-m,which is significantly greater than the seismic moment released during the 2022 event.As a result,we infer that the Luding earthquake released only a portion of the accumulated energy within the original rupture zone since 1786,indicating that the 2022 event has not caused a complete rupture in the Moxi-Shimian segment.Consequently,there remains a substantial seismic hazard in this area.

Dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates

Interactive holography offers unmatched levels of immersion and user engagement in the field of future display.Despite of the substantial progress has been made in dynamic meta-holography,the realization of real-time,highly smooth interactive holography remains a significant challenge due to the computational and display frame rate limitations.In this study,we introduced a dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates.To our knowledge,this is the first reported practical dynamic interactive metasurface holographic system.We spa-tially divided the metasurface device into multiple distinct channels,each projecting a reconstructed sub-pattern.The switching states of these channels were mapped to bitwise operations on a set of bit values,which avoids complex holo-gram computations,enabling an ultra-high computational frame rate.Our approach achieves a computational frame rate of 800 kHz and a display frame rate of 23 kHz on a low-power Raspberry Pi computational platform.According to this methodology,we demonstrated an interactive dynamic holographic Tetris game system that allows interactive gameplay,color display,and on-the-fly hologram creation.Our technology presents an inspiration for advanced dynamic meta-holography,which is promising for a broad range of applications including advanced human-computer interaction,real-time 3D visualization,and next-generation virtual and augmented reality systems.

Atomic transport dynamics in crossed optical dipole trap

We study the dynamical evolution of cold atoms in crossed optical dipole trap theoretically and experimentally. The atomic transport process is accompanied by two competitive kinds of physical mechanics, atomic loading and atomic loss.The loading process normally is negligible in the evaporative cooling experiment on the ground, while it is significant in preparation of ultra-cold atoms in the space station. Normally, the atomic loading process is much weaker than the atomic loss process, and the atomic number in the central region of the trap decreases monotonically, as reported in previous research. However, when the atomic loading process is comparable to the atomic loss process, the atomic number in the central region of the trap will initially increase to a maximum value and then slowly decrease, and we have observed the phenomenon first. The increase of atomic number in the central region of the trap shows the presence of the loading process, and this will be significant especially under microgravity conditions. We build a theoretical model to analyze the competitive relationship, which coincides with the experimental results well. Furthermore, we have also given the predicted evolutionary behaviors under different conditions. This research provides a solid foundation for further understanding of the atomic transport process in traps. The analysis of loading process is of significant importance for preparation of ultra-cold atoms in a crossed optical dipole trap under microgravity conditions.

Improved Unit Commitment with Accurate Dynamic Scenarios Clustering Based on Multi-Parametric Programming and Benders Decomposition

Stochastic unit commitment is one of the most powerful methods to address uncertainty. However, the existingscenario clustering technique for stochastic unit commitment cannot accurately select representative scenarios,which threatens the robustness of stochastic unit commitment and hinders its application. This paper providesa stochastic unit commitment with dynamic scenario clustering based on multi-parametric programming andBenders decomposition. The stochastic unit commitment is solved via the Benders decomposition, which decouplesthe primal problem into the master problem and two types of subproblems. In the master problem, the committedgenerator is determined, while the feasibility and optimality of generator output are checked in these twosubproblems. Scenarios are dynamically clustered during the subproblem solution process through the multiparametric programming with respect to the solution of the master problem. In other words, multiple scenariosare clustered into several representative scenarios after the subproblem is solved, and the Benders cut obtainedby the representative scenario is generated for the master problem. Different from the conventional stochasticunit commitment, the proposed approach integrates scenario clustering into the Benders decomposition solutionprocess. Such a clustering approach could accurately cluster representative scenarios that have impacts on theunit commitment. The proposed method is tested on a 6-bus system and the modified IEEE 118-bus system.Numerical results illustrate the effectiveness of the proposed method in clustering scenarios. Compared withthe conventional clustering method, the proposed method can accurately select representative scenarios whilemitigating computational burden, thus guaranteeing the robustness of unit commitment.

基于故障树的火电厂脱硝系统故障分析方法

脱硝系统在火电厂运行过程中扮演着重要角色,系统的正常运行以及故障预防措施的制定对火电厂正常工作具有重要意义。提出了一种基于故障树的火电厂脱硝系统故障分析方法。通过分析脱硝系统的工作原理确定全部故障事件,并根据故障事件之间的逻辑关系建立脱硝系统故障树,通过定性和定量分析确定系统的薄弱环节,对火电厂脱硝系统的各种故障制定应对方案,为企业安全生产提供指导意见。

Cooperative maneuver decision making for multi-UAV air combat based on incomplete information dynamic game

Cooperative autonomous air combat of multiple unmanned aerial vehicles(UAVs)is one of the main combat modes in future air warfare,which becomes even more complicated with highly changeable situation and uncertain information of the opponents.As such,this paper presents a cooperative decision-making method based on incomplete information dynamic game to generate maneuver strategies for multiple UAVs in air combat.Firstly,a cooperative situation assessment model is presented to measure the overall combat situation.Secondly,an incomplete information dynamic game model is proposed to model the dynamic process of air combat,and a dynamic Bayesian network is designed to infer the tactical intention of the opponent.Then a reinforcement learning framework based on multiagent deep deterministic policy gradient is established to obtain the perfect Bayes-Nash equilibrium solution of the air combat game model.Finally,a series of simulations are conducted to verify the effectiveness of the proposed method,and the simulation results show effective synergies and cooperative tactics.

妊娠高血压合并急性心肌梗死救治1例并文献复习

妊娠高血压合并急性心肌梗死的救治具有一定挑战性。本文讨论1例34岁妊娠高血压患者突发急性ST段抬高型心肌梗死(下壁)时的救治难点,提供成功救治危及该高龄孕产妇与胎儿的心血管重疾的经验与依据。本文同时检索国内外类似病例报道,冀以探讨此类少见但风险极高的孕产妇合并心血管疾病的处理策略。

Prediction of the viscosity of natural gas at high temperature and high pressure using free-volume theory and entropy scaling

Eighteen models based on two equations of state(EoS),three viscosity models,and four mixing rules were constructed to predict the viscosities of natural gases at high temperature and high pressure(HTHP)conditions.For pure substances,the parameters of free volume(FV)and entropy scaling(ES)models were found to scale with molecular weight,which indicates that the ordered behavior of parameters of Peng-Robinson(PR)and Perturbed-Chain Statistical Associating Fluid Theory(PC-SAFT)propagates to the behavior of parameters of viscosity model.Predicting the viscosities of natural gases showed that the FV and ES models respectively combined with MIX4 and MIX2 mixing rules produced the best accuracy.Moreover,the FV models were more accurate for predicting the viscosities of natural gases than ES models at HTHP conditions,while the ES models were superior to PRFT models.The average absolute relative deviations of the best accurate three models,i.e.,PC-SAFT-FV-MIX4,tPR-FVMIX4,and PC-SAFT-ES-MIX2,were 5.66%,6.27%,and 6.50%,respectively,which was available for industrial production.Compared with the existing industrial models(corresponding states theory and LBC),the proposed three models were more accurate for modeling the viscosity of natural gas,including gas condensate.

融合多尺度卷积和BiGRU网络的人类活动识别模型

基于深度学习的人类活动识别(HAR)方法在处理时间序列数据时存在手工特征提取过程复杂、复杂时序依赖性难以挖掘问题,如何有效自动提取人类活动的多尺度特征并挖掘时序前后的关联性特征,是提高HAR准确率的关键因素。为解决上述问题,提出一种多尺度一维卷积-双向门控循环单元(1DMCNN-BiGRU)模型。使用多尺度卷积提取精细化感知信号特征,同时融合双向门控循环单元(BiGRU)提取的前后整体信号的相关性特征,从而提高模型的识别准确率。在真实场景数据集USC-HAD、WISDM、PAMAP2上的实验结果表明,相较于次优的CNN-LSTM(Convolutional Neural Network with Long Short-Term Memory)模型,所提模型的识别准确率分别提高了1.06%、1.23%和1.71%,具有较高的识别准确度,验证了所提模型用于HAR的有效性。

Acousto-optic scanning spatial-switching multiphoton lithography

Nano-3D printing has obtained widespread attention owing to its capacity to manufacture end-use components with nano-scale features in recent years.Multiphoton lithography(MPL)is one of the most promising 3D nanomanufacturing technologies,which has been widely used in manufacturing micro-optics,photonic crystals,microfluidics,meta-surface,and mechanical metamaterials.Despite of tremendous potential of MPL in laboratorial and industrial applications,simultaneous achievement of high throughput,high accuracy,high design freedom,and a broad range of material structuring capabilities remains a long-pending challenge.To address the issue,we propose an acousto-optic scanning with spatial-switching multispots(AOSS)method.Inertia-free acousto-optic scanning and nonlinear swept techniques have been developed for achieving ultrahigh-speed and aberration-free scanning.Moreover,a spatial optical switch concept has been implemented to significantly boost the lithography throughput while maintaining high resolution and high design freedom.An eight-foci AOSS system has demonstrated a record-high 3D printing rate of 7.6×10^(7)voxel s^(-1),which is nearly one order of magnitude higher than earlier scanning MPL,exhibiting its promise for future scalable 3D nanomanufacturing.

Multi-foci metalens for spectra and polarization ellipticity recognition and reconstruction

Multispectral and polarized focusing and imaging are key functions that are vitally important for a broad range of optical applications.Conventional techniques generally require multiple shots to unveil desired optical information and are implemented via bulky multi-pass systems or mechanically moving parts that are difficult to integrate into compact and integrated optical systems.Here,a design of ultra-compact transversely dispersive metalens capable of both spectrum and polarization ellipticity recognition and reconstruction in just a single shot is demonstrated with both coherent and incoherent light.Our design is well suited for integrated and high-speed optical information analysis and can significantly reduce the size and weight of conventional devices while simplifying the process of collecting optical information,thereby promising for various applications,including machine vision,minimized spectrometers,material characterization,remote sensing,and other areas which require comprehensive optical analysis.

石灰岩-砂岩组合骨料混凝土力学特性试验研究

优质石灰岩骨料与地缘性砂岩骨料形成组合骨料,可提高资源利用率,具有良好的社会经济效益。设置5种不同石灰岩与砂岩质量占比组合,系统开展不同石灰岩与砂岩占比组合骨料对混凝土力学特性影响规律研究,为组合骨料的实际工程运用提供理论依据。研究表明,组合骨料中石灰岩与砂岩占比对混凝土抗压强度及弹性模量存在显著影响,而对其劈裂抗拉强度影响甚微。组合骨料混凝土抗压强度及弹性模量随石灰岩占比提高而增大,纯石灰岩骨料混凝土抗压强度及弹性模量较纯砂岩骨料混凝土分别增加了28.77%、36.23%,石灰岩骨料占比的提升显著提高了混凝土强度及刚度。石灰岩及砂岩骨料级配相近条件下,石灰岩骨料推荐低占比区间为0%~20%,且经济效益良好;推荐高占比区间为50%~80%,应尽量避开区间为20%~50%。