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Journal of Environmental Sciences 2013年第3期25卷 531-536页

作者： Jinze lv Lizhong Zhu Department of Environmental Science Zhejiang University Zhejiang Province Key Laboratory of Organic Pollution Process and Control

Central ventilation and air conditioner systems are widely utilized nowadays in public places for air exchange and temperature control,which significantly influences the transfer of pollutants between indoors and *** study the effect of central ventilation and air conditioner systems on the concentration and health risk from airborne pollutants,a spatial and temporal survey was carried out using polycyclic aromatic hydrocarbons （PAHs） as agent *** the period when the central ventilation system operated without air conditioning （AC-off period）,concentrations of 2-4 ring PAHs in the model supermarket were dominated by outdoor levels,due to the good linearity between indoor air and outdoor air （rp〉0.769,p〈0.05）,and the slopes （1.2-4.54） indicated that ventilating like the model supermarket increased the potential health risks from low molecular weight *** the period when the central ventilation and air conditioner systems were working simultaneously （AC-on period）,although the total levels of PAHs were increased,the concentrations and percentage of the particulate PAHs indoors declined *** BaP equivalency （BaPeq） concentration indicated that utilization of air conditioning reduced the health risks from PAHs in the model supermarket.

关键词： particulate gaseous PAHs health risk public place

Error- and loss-tolerant bundle fragment authentication for space DTNs

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Frontiers of Computer Science 2014年第6期8卷 1012-1023页

作者： Xixiang lv Hui LI The National Key Lab of Integrated Services Networks Xidian University Xi'an 710071 China

To ensure the authenticity and integrity of bundles, the in-transit PDUs of bundle protocol （BP） in space delay/disruption-tolerant networks （DTNs）, the bundle security protocol specification （IRTF RFC6257） suggested using a digital signature directly over each bundle. However, when bundle fragment services are needed, this mechanism suffers from heavy computational costs, bandwidth overheads and energy consumption. In this paper, we address the fragment authentication issue for BP by exploiting the combination of RS error correction and erasure codes with the help of batch transmission characteristic of DTNs. The RS error correction and erasure codes are adopted to allow the receivers to locate the false/injected fragments and reconstruct the only one signature shared by all fragments of a bundle, even if some other fragments are lost or routed to a different path. Getting only partial authentic fragments, a DTN node is able to detect and filter the false/injected fragments, and authenticate the origin of a bundle as well. Such an approach tolerates high delays, unexpected link disruption and the BP nature of routing fragments of the same bundle possibly via different paths. The performance analysis demonstrates that both of our schemes, which follow our generic idea based on RS codes, significantly reduce bandwidth overheads and computational costs as compared to the prior works.

关键词： space-based delay tolerant networks bundle authentication information security.

Measurements of convection electric field in the inner magnetosphere

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Science China(Technological Sciences) 2018年第12期61卷 1866-1871页

作者： lv Xin LIU WenLong School of Space and Environment Beihang University

In this paper, we study the characteristic of large-scale convection electric field in the inner magnetosphere, using magnetospheric multiscale(MMS) observations between L=5 and L=8 over the period from September 1, 2015 to October 31, 2016,covering almost all magnetic local time(MLT). Observations show that the DC convection electric field generally has small variations in this region. We investigate whether the convection electric field is correlated with geomagnetic indices and solar wind parameters. It is found that, among the studied parameters, solar wind electric field, z component of interplanetary magnetic field, AE and Kp indices show good correlations with the averaged convection electric field. The results in this paper provide valuable information for understanding the role of electric field on the dynamics of the inner magnetosphere.

关键词： convection electric field inner magnetosphere

A direct probabilistic approach to solve state equations for nonlinear systems under random excitation

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Acta Mechanica Sinica 2016年第5期32卷 941-958页

作者： Zheng lv Zhiping Qiu Institute of Solid Mechanics Beihang University

In this paper, a direct probabilistic approach（DPA） is presented to formulate and solve moment equations for nonlinear systems excited by environmental loads that can be either a stationary or nonstationary random *** proposed method has the advantage of obtaining the response＇s moments directly from the initial conditions and statistical characteristics of the corresponding external excitations. First, the response＇s moment equations are directly derived based on a DPA, which is completely independent of the It？/filtering approach since no specific assumptions regarding the correlation structure of excitation are *** solving them under Gaussian closure, the response＇s moments can be obtained. Subsequently, a multiscale algorithm for the numerical solution of moment equations is exploited to improve computational efficiency and avoid much wall-clock time. Finally, a comparison of the results with Monte Carlo（MC） simulation gives good ***, the advantage of the multiscale algorithm in terms of efficiency is also demonstrated by an engineering example.

关键词： Direct probabilistic approach Nonlinear dynamic system Nonstationary random process Response’s moments Multiscale algorithm

High-order discontinuous Galerkin method for applications to multicomponent and chemically reacting flows

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Acta Mechanica Sinica 2017年第3期33卷 486-499页

作者： Yu lv Matthias Ihme Department of Mechanical Engineering Stanford University

This article focuses on the development of a discontinuous Galerkin (DG) method for simulations of multicomponent and chemically reacting flows. Compared to aerodynamic flow applications, in which DG methods have been successfully employed, DG simulations of chemically reacting flows introduce challenges that arise from flow unsteadiness, combustion, heat release, compressibility effects, shocks, and variations in thermodynamic properties. To address these challenges, algorithms are developed, including an entropy-bounded DG method, an entropy-residual shock indicator, and a new formulation of artificial viscosity. The performance and capabilities of the resulting DG method are demonstrated in several relevant applications, including shock/bubble interaction, turbulent combustion, and detonation. It is concluded that the developed DG method shows promising performance in application to multicomponent reacting flows. The paper concludes with a discussion of further research needs to enable the application of DG methods to more complex reacting flows.

关键词： Discontinuous Galerkin method High-order schemes Reacting flows Multicomponent flows

A fast forward computational method for nuclear measurement using volumetric detection constraints

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Nuclear Science and Techniques 2024年第2期35卷 47-63页

作者： Qiong Zhang Lin-lv Lin University of Electronic Science and Technology of China Chengdu 610000China

Owing to the complex lithology of unconventional reservoirs,field interpreters usually need to provide a basis for interpretation using logging simulation *** the various detection tools that use nuclear sources,the detector response can reflect various types of information of the *** Monte Carlo method is one of the primary methods used to obtain nuclear detection responses in complex ***,this requires a computational process with extensive random sampling,consumes considerable resources,and does not provide real-time response ***,a novel fast forward computational method(FFCM)for nuclear measurement that uses volumetric detection constraints to rapidly calculate the detector response in various complex environments is ***,the data library required for the FFCM is built by collecting the detection volume,detector counts,and flux sensitivity functions through a Monte Carlo ***,based on perturbation theory and the Rytov approximation,a model for the detector response is derived using the flux sensitivity function method and a one-group diffusion *** environmental perturbation is constrained to optimize the model according to the tool structure and the impact of the formation and borehole within the effective detection ***,the method is applied to a neutron porosity tool for *** various complex simulation environments,the maximum relative error between the calculated porosity results of Monte Carlo and FFCM was 6.80%,with a rootmean-square error of 0.62 *** field well applications,the formation porosity model obtained using FFCM was in good agreement with the model obtained by interpreters,which demonstrates the validity and accuracy of the proposed method.

关键词： Nuclear measurement Fast forward computation Volumetric constraints

The Dragon Boat Festival绘本教学设计

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英语教师 2025年第1期 68-73页

作者：吕月云吴青梅(指导) 福建省泉州市鲤城区实验小学福建泉州362000 福建省普通教育研究室

一、教学内容。The Dragon Boat Festival选自翼渡英语分级阅读《文化中国英语学习绘本》系列初阶下。该绘本故事讲述了华华到屈原故里秭归县观看端午龙舟赛,并逐步了解秭归当地特有的端午节习俗的故事。

关键词：绘本教学绘本故事龙舟赛屈原故里端午节教学内容

颗粒弥散和核-壳共存的TiCN基金属陶瓷的制备

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复合材料学报 2020年第10期37卷 2552-2560页

作者：宋金鹏高姣姣吕明太原理工大学机械与运载工程学院及精密加工山西省重点实验室太原030024

为了制备具有良好综合力学性能的TiCN基金属陶瓷,研究了烧结温度对TiCN-HfN陶瓷微观结构和力学性能的影响,构建了颗粒弥散和核-壳共存的微观结构模型,揭示了材料的致密化机制、增硬机制、增韧补强机制。结果表明:在1 500℃下所制备的TiC... 详细信息

为了制备具有良好综合力学性能的TiCN基金属陶瓷,研究了烧结温度对TiCN-HfN陶瓷微观结构和力学性能的影响,构建了颗粒弥散和核-壳共存的微观结构模型,揭示了材料的致密化机制、增硬机制、增韧补强机制。结果表明:在1 500℃下所制备的TiCN-HfN材料具有颗粒弥散与核-壳共存的微观结构,其中弥散的颗粒为HfN,核为TiCN,壳主要为(Ti, Hf, Mo)CN固溶体;材料具有较好的性能,其相对密度为99.7%、硬度为20.6 GPa、抗弯强度为1 682.5 MPa、断裂韧度为8.5 MPa·m1/2;其致密化机制主要为颗粒和金属液相填充到烧结颈实现致密化,增硬机制主要为致密化和颗粒钉扎强化增硬,增韧补强机制主要为颗粒弥散和颗粒钉扎增韧、骨架结构和颗粒钉扎增强。

关键词： TiCN-HfN陶瓷颗粒弥散核-壳结构力学性能微观结构

Ultra-Short Wave Communication Squelch Algorithm Based on Deep Neural Network

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Big Data Mining and Analytics 2023年第1期6卷 106-114页

作者： Yuanxin Xiang Yi lv Wenqiang Lei Jiancheng lv College of Computer Science Sichuan UniversityChengdu 610000China Sichuan Research Institute Shanghai Jiao Tong UniversityChengdu 610000China

The squelch problem of ultra-short wave communication under non-stationary noise and low Signal-to-Noise Ratio(SNR)in a complex electromagnetic environment is still *** alleviate the problem,we proposed a squelch algorithm for ultra-short wave communication based on a deep neural network and the traditional energy decision *** proposed algorithm first predicts the speech existence probability using a three-layer Gated Recurrent Unit(GRU)with the speech banding spectrum as the *** it gets the final squelch result by combining the strength of the signal energy and the speech existence *** simulations and experiments are done to verify the robustness and effectiveness of the proposed *** simulate the algorithm in three situations:the typical Amplitude Modulation(AM)and Frequency Modulation(FM)in the ultra-short wave communication under different SNR environments,the non-stationary burst-like noise environments,and the real received signal of the ultra-short wave *** experimental results show that the proposed algorithm performs better than the traditional squelch methods in all the simulations and *** particular,the false alarm rate of the proposed squelch algorithm for non-stationary burst-like noise is significantly lower than that of traditional squelch methods.

关键词： squelch Gated Recurrent Unit(GRU) ultra-short wave communication

Synergism and anion-cation dual chemical substitution in heterostructure sprouted on MXene enable high-efficiency and stable overall water splitting

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Journal of Materials Science & Technology 2023年第16期147卷 207-216页

作者： Zepeng lv Jinshuai Fei Yang You Xuewei lv Qian Li Jie Dang College of Materials Science and Engineering Chongqing UniversityChongqing 400044China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China State Key Laboratory of Advanced Special Steels&Shanghai Key Laboratory of Advanced Ferrometallurgy School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

The exploration of novel,super-potent and low-cost electrocatalysts for water splitting has always been the kernel in the field of renewable ***,exfoliated Ti_(3)C_(2)T_(x) MXenes work as a substrate to vertically grow polypore N,Ni-Co2P nanoarrays(N,Ni-Co2P@TC)through an in situ interface-growth strategy and subsequent phosphorization and *** well-defined heterointerfaces with positive and negative ions co-modulation as coupled hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts for efficient overall water splitting are investigated,which possesses excellent durability even at a large current density(±500 mA cm^(-2)).For HER,suitable H_(2)O∗and H∗absorption energies and accelerated electronic transmission make N,Ni-Co2P@TC display a low overpotential of 27 mV at-10 mA cm^(-2) and Tafel slope of 38 mV dec^(–1) in 1 mol/L *** OER,the synergy of N,Ni-Co2P@TC with selfreconfiguration can give enhanced activity with a low overpotential of 232 mV at 10 mA cm^(-2) and a Tafel slope of 57 mV dec^(–1).Additionally,the excellent bifunctional activity allows easily combining for efficient overall water splitting with a low driving voltage(1.51 V)at 10 mA cm^(-2),and the electrolyzer can be driven by a 1.5 V AAA battery.

关键词： Synergism Chemical substitution Heterostructure Overall water splitting MXene