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Adsorption dynamics of ethane from air in structured fixed beds with different microfibrous composites

Chinese Journal of Chemical Engineering 2023年第1期53卷 14-24页

作者： Huan Xiang Huiping Zhang PengFei Liu Ying Yan School of Chemistry and Chemical Engineering Guangdong Provincial Key Laboratory of Green Chemical Product TechnologySouth China University of TechnologyGuangzhou 510640China Energy and Bioproducts Research Institute(EBRI) Aston UniversityBirmingham B47ETUnited Kingdom

Adsorption dynamics of ethane in two granular fixed beds and structured fixed beds with microfibrous composites was studied.5A zeolite membrane 5A/PSSF(paper-like sintered stainless steel fiber)and microfibrous entrapped activated carbon(MEAC)composites were prepared by wet layup papermaking/sintering technique and in-situ hydrothermal method.Microfibrous composites were characterized by X-ray diffraction,scanning electron microscopy and N2 adsorption/desorption.Structured fixed beds were designed by filling granular adsorbents(5A zeolite or activated carbon)and microfibrous composites at the inlet and outlet of the beds,respectively.Effects of flow rate,bed height and structure on the breakthrough curves were investigated.The length of unused bed(LUB)was determined,and Yoon–Nelson model was used to fit the breakthrough curves.The experimental results showed ethane was effectively adsorbed on the granular adsorbents and microfibrous composites.Both composites could decrease the LUB values and enhance bed utilization.All breakthrough curves fitted well to Yoon–Nelson model,with correlation coefficient exceeding 0.89.The adsorption rate of ethane could be improved in the structured fixed beds,which showed an enhanced mass transfer efficiency for ethane adsorption.LUB values of structured fixed beds with 5A/PSSF composites were larger,the bed utilization values were lower,and the adsorption rate constants were higher than those with MEAC composites under the same conditions.

关键词： 5A zeolite membrane Microfibrous entrapped activated carbon Ethane Structured fixed bed Adsorption dynamics

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Rural vehicle emission as an important driver for the variations of summertime tropospheric ozone in the Beijing-Tianjin-Hebei region during 2014-2019

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Journal of Environmental Sciences 2022年第4期34卷 126-135页

作者： Yifei Song Yuanyuan Zhang Junfeng liu Chenglong Zhang Chengtang liu PengFei Liu Yujing Mu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Center for Excellence in Urban Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

Tropospheric ozone(O_(3))pollution is increasing in the Beijing-Tianjin-Hebei(BTH)region despite a significant decline in atmospheric fine aerosol particles(PM_(2.5))in recent years.However,the intrinsic reason for the elevation of the regional O_(3)is still unclear.In this study,we analyzed the spatio-temporal variations of tropospheric O_(3)and relevant pollutants(PM_(2.5),NO_(2),and CO)in the BTH region based on monitoring data from the China Ministry of Ecology and Environment during the period of 2014-2019.The results showed that summertime O_(3)concentrations were constant in Beijing(BJ,0.06μg/(m^(3)·year))but increased significantly in Tianjin(TJ,9.09μg/(m^(3)·year))and Hebei(HB,6.06μg/(m3·year)).Distinct O_(3)trends between Beijing and other cities in BTH could not be attributed to the significant decrease in PM_(2.5)(from-5.08 to-6.32μg/(m3·year))and CO(from-0.053 to-0.090 mg/(m^(3)·year))because their decreasing rates were approximately the same in all the cities.The relatively stable O_(3)concentrations during the investigating period in BJ may be attributed to a faster decreasing rate of NO_(2)(BJ:-2.55μg/(m^(3)·year);TJ:-1.16μg/(m^(3)·year);HB:-1.34μg/(m3·year)),indicating that the continued reduction of NOx will be an effective mitigation strategy for reducing regional O_(3)pollution.Significant positive correlations were found between daily maximum8 hr average(MDA8)O_(3)concentrations and vehicle population and highway freight transportation in HB.Therefore,we speculate that the increase in rural NO_(x)emissions due to the increase in vehicle emissions in the vast rural areas around HB greatly accelerates regional O_(3)formation,accounting for the significant increasing trends of O_(3)in HB.

关键词： Tropospheric ozone The Beijing-Tianjin-Hebei region Spatio-temporal trends Rural vehicle emission

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The behavior of a lithospheric magnetization and magnetic field model

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Earth and Planetary Physics 2023年第1期7卷 66-73页

作者： PengFei Liu Yi Jiang Qing Yan Ann MHirt State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacaoChina CNSA Macao Center for Space Exploration and Science MacaoChina Institute of Geophysics ETH ZürichSonneggstrasse 5CH-8095 ZürichSwitzerland

The Earth’s“lithosphere”is its outer shell,made up of the Earth’s crust and outermost mantle.The part of the Earth’s magnetic field that originates in the lithosphere consists of a superposition of magnetic anomalies with a broad spectrum of sizes and intensities,which arise from geological and tectonic features.The lithospheric magnetic field is known from surface observations,and on larger scales from above-surface measurements.The increase in recent decades of satellites dedicated to measuring the Earth’s magnetic field has improved significantly our models of the Earth’s magnetic environment.Based on these increasing observations,a number of comprehensive field models have been constructed,some of which focus solely on the lithosphere,such as the MF model series.We present a map of lithospheric magnetic anomalies at 400 km altitude,based on a vertically integrated magnetization model.This height was chosen because it is the expected orbital altitude of the Macao Science Satellite-1(MSS-1)mission.The model presented herein indicates that the amplitude of the lithospheric anomalies at 400 km altitude is between-14.8 n T and 18.2 n T.This information is useful because it provides a reference for the lithospheric source of the Earth’s magnetic field that contributes to the magnetic measurements made from satellite instruments.The low inclination orbit of the MSS-1 mission will provide information that is sensitive to lateral variation within the lithosphere;these variations arise from plate tectonic features with longitudinal extent.In conclusion,the new MSS-1mission will provide valuable information in detecting compositional variations in the lithosphere,and in delineating large-scale geological structures.

关键词： vertically integrated magnetization lithospheric magnetic field field model MSS-1

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A review of low-carbon technologies and projects for the global cement industry

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Journal of Environmental Sciences 2024年第2期136卷 682-697页

作者： Yangyang Guo Lei Luo Tingting liu Liwei Hao Yinming Li PengFei Liu Tingyu Zhu CAS Key Laboratory of Green Process and Engineering Institute of Process EngineeringInnovation Academy for Green ManufactureChinese Academy of SciencesBeijing 100190China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China State Key Laboratory of Solid Waste Reuse for Building Materials Beijing Building Materials Academy of Sciences ResearchBeijing 100041China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou 341000China

Carbon dioxide(CO_(2))emissions from the cement industry account for 26%of the total industrial emissions,and the need to develop low-carbon techniques within the cement industry is extremely urgent.Low-carbon projects and technologies for the cement industry in different regions and countries have been thoroughly reviewed in this manuscript,and the low-carbon development concept for each county has been analyzed.For developing countries such as China and India,energy saving and efficiency enhancement are currently the key points,while for developed countries and regions such as Europe,more efforts have been focused on carbon capture,utilization,and storage(CCUS).Global CCUS projects have been previously conducted,and the majority of CCUS projects are currently performed in Europe where major projects such as the CEMCAP,CLEANKER,and IEILAC projects represent the latest research progress in cement production technologies and low-carbon technologies for the global cement industry.The development of low-carbon cement technologies has changed from focusing on the end point to instead focusing on the source and process through the exploration of hydrogen and solar energies,and more disruptive and original technologies are expected to be developed,particularly in the cement industry in China.

关键词： Cement industry CO_(2)emissions Low carbon development Projects Carbon capture utilization and storage

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Research on hunting stability and bifurcation characteristics of nonlinear stochastic wheelset system

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Applied Mathematics and Mechanics(English Edition) 2023年第3期44卷 431-446页

作者： Peng WANG Shaopu YANG Yongqiang liu PengFei Liu Xing ZHANG Yiwei ZHAO State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Traffic and Transportation Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

A stochastic wheelset model with a nonlinear wheel-rail contact relationship is established to investigate the stochastic stability and stochastic bifurcation of the wheelset system with the consideration of the stochastic parametric excitations of equivalent conicity and suspension stiffness.The wheelset is systematized into a onedimensional(1D)diffusion process by using the stochastic average method,the behavior of the singular boundary is analyzed to determine the hunting stability condition of the wheelset system,and the critical speed of stochastic bifurcation is obtained.The stationary probability density and joint probability density are derived theoretically.Based on the topological structure change of the probability density function,the stochastic Hopf bifurcation form and bifurcation condition of the wheelset system are determined.The effects of stochastic factors on the hunting stability and bifurcation characteristics are analyzed,and the simulation results verify the correctness of the theoretical analysis.The results reveal that the boundary behavior of the diffusion process determines the hunting stability of the stochastic wheelset system,and the left boundary characteristic value cL=1 is the critical state of hunting stability.Besides,stochastic D-bifurcation and P-bifurcation will appear in the wheelset system,and the critical speeds of the two kinds of stochastic bifurcation decrease with the increase in the stochastic parametric excitation intensity.

关键词： stochastic wheelset system stochastic average method singular boundary hunting stability stochastic Hopf bifurcation

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Experimental investigation of rigid confinement effects of radial strain on dynamic mechanical properties and failure modes of concrete

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International Journal of Mining Science and Technology 2021年第5期31卷 939-951页

作者： PengFei Liu Xiaoping Zhou Qihu Qian School of Civil Engineering Chongqing UniversityChongqing 400044China School of Civil Engineering Wuhan UniversityWuhan 430072China PLA University of Science and Technology Nanjing 210007China

In this study,to confirm the effect of confining pressure on dynamic mechanical behavior and failure modes of concrete,a split Hopkinson pressure bar dynamic loading device was utilized to perform dynamic compressive experiments under confined and unconfined conditions.The confining pressure was achieved by applying a lateral metal sleeve on the testing specimen which was loaded in the axial direction.The experimental results prove that dynamic peak axial stress,dynamic peak lateral stress,and peak axial strain of concrete are strongly sensitive to the strain rate under confined conditions.Moreover,the failure patterns are significantly affected by the stress-loading rate and confining pressure.Concrete shows stronger strain rate effects under an unconfined condition than that under a confined condition.More cracks are created in concrete subjected to uniaxial dynamic compression at a higher strain rate,which can be explained by a thermal-activated mechanism.By contrast,crack generation is prevented by confinement.Fitting formulas of the dynamic peak stress and dynamic peak axial strain are established by considering strain rate effects(50–250 s-1)as well as the dynamic confining increase factor(DIFc).

关键词： Strain rate effect Multiaxial loading Dynamic peak axial stress Thermo-activated mechanism Dynamic increase factor

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Seismic assessment of RC frames infilled with innovative CFS walls considering seismic orientation effect

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Science China(Technological Sciences) 2023年第2期66卷 417-428页

作者： liu pengfei LI LuXi School of Civil Engineering Shenyang Jianzhu UniversityShenyang 110168China Guangzhou University-Curtin University Joint Research Centre for Structural Monitoring and Protection Against Multi-Dynamic Hazards School of Civil EngineeringGuangzhou UniversityGuangzhou 510006China

The metal tailings porous concrete cold-formed steel(MCFS)wall is an innovative cold-formed steel(CFS)wall with good thermal and mechanical properties,which has the potential to be widely utilized as the infilled wall(IW).In this paper,the MCFS walls are adopted in the reinforced concrete(RC)frame,and the seismic performance of the building subjected to ground motions with various incidence angles are investigated.Three-dimensional finite element model of the studied building is developed with full consideration of the in-plain(IP)and out-of-plane(OP)behavior of MCFS walls.Incremental dynamic analysis is conducted to obtain the deformation responses of frames and damage ratios of MCFS walls under the combined effect of seismic intensity and orientation.Fragility curves are generated to assess the seismic performance of the building and investigate the effect of ground motion orientation.The results validate the superior performance of infilled MCFS walls,and reveal that the seismic orientation has a considerable impact on the response along each reference axis of the structure.Furthermore,different incidence angles induce up to 10.2%and 14.4%variations in the median Sa(T1)of fragilities for the frames in X and Y axes,and the corresponding change rates in the median Sa(T1)for the walls are 13.5%and 15.1%,respectively.However,for the overall performance of the building,the seismic orientation effect is less significant.The rates of changes in median Sa(T1)are less than 4%for both frames and MCFS walls.

关键词： metal tailings porous concrete CFS wall RC frame in-plane out-of-plane orientation effect

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Rice disease identification method based on improved CNN-BiGRU

Artificial Intelligence in Agriculture

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Artificial Intelligence in Agriculture 2023年第3期9卷 100-109页

作者： Yang Lu Xiaoxiao Wu PengFei Liu Hang Li Wanting liu Colloge of Information and Electrical Engineering Heilongjiang Bayi Agricultural UniversityDaqingHeilongjiang 163319China Artificial Intelligence Energy Research Institute Northeast Petroleum UniversityDaqingHeilongjiang 163318China Sanya Offshore Oil and Gas Research Institute Northeast Petroleum UniversitySanyaHainan 572025China

In the field of precision agriculture,diagnosing rice diseases from images remains challenging due to high error rates,multiple influencing factors,and unstable conditions.While machine learning and convolutional neural networks have shown promising results in identifying rice diseases,they were limited in their ability to explain the relationships among disease features.In this study,we proposed an improved rice disease classification method that combines a convolutional neural network(CNN)with a bidirectional gated recurrent unit(BiGRU).Specifically,we introduced a residual mechanism into the Inception module,expanded the module's depth,and integrated an improved Convolutional Block Attention Module(CBAM).We trained and tested the improved CNN and BiGRU,concatenated the outputs of the CNN and BiGRU modules,and passed them to the classification layer for recognition.Our experiments demonstrate that this approach achieves an accuracy of 98.21%in identifying four types of rice diseases,providing a reliable method for rice disease recognition research.

关键词： Deep learning CNN-BiGRU Rice disease Feature relationship

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面向未来低碳道路养护的超薄罩面功能性研究综述

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Engineering 2024年第1期32卷 82-98页

作者： Meng Guo Rui Zhang Xiuli Du PengFei Liu State Key Laboratory of Bridge Engineering Safety and Resilience Beijing University of TechnologyBeijing 100124China The Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China Institute of Highway Engineering RWTH Aachen UniversityAachen 52074Germany

Highway maintenance mileage reached 5.25 million kilometers in China by2021.Ultra-thin overlay is one of the most commonly used maintenance technologies,which can significantly enhance the eco-nomic and environmental benefits of pavements.To promote the low-carbon development of ultra-thin overlays,this paper mainly studied the mechanism and influencing factors of several ultra-thin over-lay functions.Firstly,the skid resistance,noise reduction,rutting resistance,and crack resistance of ultra-thin overlays were evaluated.The results indicated that the high-quality aggregates improved the skid and rutting resistance of ultra-thin overlay by 5%-20%.The optimized gradations and modifed binders reduced noise of ultra-thin overlay by 0.4-6.0 dB.The high viscosity modified binders improved the rut-ting resistance of ultra-thin overlay by about 10%-130%.Basalt fiber improved the cracking resistance of ultra-thin overlay by more than 20%.Due to the thinner thickness and better road performance,the performance-based engineering cost of ultra-thin overlay was reduced by about 30%-40%compared with conventional overlays.Secondly,several environ mentally friendly functions of ultra-thin overlay were investigated,including snow melting and deicing,exhaust gas purification and pavement cooling.The lower thickness of ultra-thin overlay was conducive to the diffusion of chloride-based materials to the pavement surface.Therefore,the snow melting effect of self-ice-melting was better.In addition,the ultra-thin overlay mixture containing photocatalytic materials could decompose 20%-50%of the exhaust gas.The colored ultra-thin overlay was able to reduce the temperature of the pavement by up to 8.1C.The temperature difference between the upper and lower surfaces of the ultra-thin overlay containing thermal resistance materials could reach up to 12.8C.In addition,numerous typical global engineering applications of functional ultra-thin overlay were summarized.This review can help better understand the functionality of ultra-thin overla

关键词： Road maintenance Ultra-thin overlay Snow melting and deicing Exhaust gas purification Pavement cooling Low-carbon

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Evaluation of offline sampling for atmospheric C3-C11 non-methane hydrocarbons

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Journal of Environmental Sciences 2022年第3期34卷 132-140页

作者： Zhiguo liu Chengtang liu Zhouming He Yujing Mu Chenglong Zhang Yuanyuan Zhang PengFei Liu Yuzheng Wang Junfeng liu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Center for Excellence in Urban Atmospheric Environment Institute of Regional EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China Clear Science&Technology Co. LtdBeijing 100029China

The concentration variation of C3-C11 non-methane hydrocarbons(NMHCs)collected in several types of commercial flexible bags and adsorption tubes was systematically inves-tigated using a gas chromatography-flame ionization detector(GC-FID)system.The per-centage loss of each NMHC in the polyvinyl fluoride(PVF)bags was less than 5%during a 7-hr storage period;significant NMHCs loss was detected in aluminum foil composite film and fluorinated ethylene propylene bags.The thermal desorption efficiency of NMHCs for adsorption tubes filled Carbopack B and Carboxen1000 sorbents was greater than 95%at 300℃,and the loss of NMHCs in the adsorption tubes during 20-days storage at 4℃was less than 8%.The thermal desorption efficiency for C11 NMHCs in the adsorption tube filled with Carbograph 1 and Carbosieve SⅢabsorbents was less than 40%at 300℃,and pyrolysis of the absorbents at 330℃interfered significantly with the measurements of some alkenes.The loss of alkenes was significant when NMHCs were sampled by cryo-enrichment at-90℃in the presence of O3 for the online NMHC measurements,and negligible for enrichment us-ing adsorption tubes at 25℃.Although O_(3)scrubbers have been widely used to eliminate the influence of O_(3)on NMHC measurements,the loss of NMHCs with carbon numbers greater than 8 was more than 10%.Therefore,PVF bags and adsorption tubes filled Carbopack B and Carboxen1000 sorbents were recommended for the sampling of atmospheric NMHCs.

关键词： Non-methane hydrocarbons(NMHCs) Gas chromatography-flame ionization detector(GC-FID) Offline sampling Adsorption tubes Ozone scrubber

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