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Regulated emission characteristics of in-use LNG and diesel semi-trailer towing vehicles under real driving conditions using PEMS

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Journal of Environmental Sciences 2020年第2期32卷 155-164页

作者： Liqun Lv Yunshan Ge Zhe Ji Jianwei Tan Xin Wang Lijun Hao Zhiwei Wang Mengzhu Zhang Chunjie Wang Haidan Liu National Laboratory of Auto Performance&Emission Test School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China Vehicle Emission Control Center Chinese Research Academy of Environmental SciencesBeijing 100081China Tangshan Environmental monitoring centre Tangshan 063000China

On-road driving emissions of six liquefied natural gas(LNG) and diesel semi-trailer towing vehicles(STTVs) which met China Emission Standard IV and V were tested using Portable Emission Measurement System(PEMS) in northern *** characteristics of these vehicles under real driving conditions were analyzed and proved that on-road emissions of heavy-duty vehicles(HDVs) were underestimated in the *** were large differences among LNG and diesel vehicles, which also existed between China V vehicles and China IV *** factors showed the highest level under real driving conditions, which probably be caused by frequent acceleration, deceleration, and *** emission factors ranged from 2.855 to 20.939 g/km based on distance-traveled and 6.719–90.557 g/kg based on fuel consumption during whole tests, which were much higher than previous researches on chassis *** was inferred from tests that the fuel consumption rate of the test vehicles had a strong correlation with NOx emission, and the exhaust temperature also affected the efficiency of Selected Catalytic Reduction(SCR) aftertreatment system, thus changing the NOx emission *** emission factors of LNG vehicles were 2.012–10.636 g/km, which were much higher than that of diesel vehicles(0.029–0.185 g/km).Unburned CH4 may be an important reason for this *** on-road emission tests, especially CH4 emission test should be carried out in subsequent *** addition, the Particulate Number(PN) emission factors of diesel vehicles were at a very high level during whole tests, and Diesel Particulate Filter(DPF)should be installed to reduce PN emission.

关键词： Semi-trailer towing vehicles Regulated emission PEMS

Methods for automatic identification and extraction of terraces from high spatial resolution satellite data(China-GF-1)

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International Soil and Water Conservation Research 2017年第1期5卷 17-25页

作者： Yi Zhang Mingchang Shi Xin Zhao Xiaojing Wang Zhidong Luo Yuan Zhao Beijing Forestry University Beijing 100083China Beijing Datum Technology Development CO. LTD.Beijing 100084China monitoring centre of Soil and Water Conservation Ministry of Water ResourcesBeijing 100053China

Terraces are effective measures to control soil and water loss on hillslopes and play significant roles in water storage,soil conservation and increasing of crop *** the launch of comprehensive management engineering of transforming slopes into terraces in China,the area of terraces is continuously *** plan for soil and water conservation in a scientific way and ensure rational soil and water conservation measures,it is important to determine a timely and accurate inventory of the spatial distribution of the existing ***-resolution satellite data(China GF-1)was used in this study to automatically identify and extract *** edge characteristics statistics algorithm,template-matching algorithm and the Fourier transformation algorithm were *** results suggest that the template-matching algorithm,based on high gray features of terraces,has higher identification accuracy and lower extraction miss rate,and is able to determines the complete map spots,which works well for identification and extraction of typical *** Fourier transformation algorithm,based on the texture of the terraces,is easily affected by gray changes on the terrace field surfaces and field ridges and is hardly reliable as a stand-alone technique for terrace *** this study,we focused on an area near Hengshan County,Yulin of Shanxi Province,and performed field validation of the terrace automatic identification and extraction *** results suggest that the accuracy of automatic identification and extraction of the terraces is greater than 80%.The method proposed is helpful to meet the requirements for planning and monitoring soil and water conservation projects.

关键词： Terraces Remote sensing Edge characteristics Fourier transformation China-GF-1

An open compute and data federation as an alternative to monolithic infrastructures for big Earth data analytics

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Big Earth Data 2023年第3期7卷 812-830页

作者： Björn Backeberg ZdeněkŠustr Enol Fernández Gennadii Donchyts Arjen Haag J.B.Raymond Oonk Gerben Venekamp Benjamin Schumacher Stefan Reimond Charis Chatzikyriakou Deltares DelftThe Netherlands Nansen Environmental and Remote Sensing Center BergenNorway CESNET PragueCzech Republic EGI Foundation AmsterdamThe Netherlands SURF/SURFsara AmsterdamThe Netherlands Earth Observation Data centre for Water Resources monitoring GmbH ViennaAustria

An adequate compute and storage infrastructure supporting the full exploitation of Copernicus and Earth Observation datasets is currently not available in *** paper presents the cross-disciplinary open-source technologies being leveraged in the C-SCALE project to develop an open federation of compute and data providers as an alternative to monolithic infrastructures for processing and analysing Copernicus and Earth Observation *** critical aspects of the federation and the chosen technologies are elaborated upon:(1)federated data discovery,(2)federated access and(3)software *** these technologies the open federation aims to provide homogenous access to resources,thereby enabling its users to generate meaningful results quickly and *** will be achieved by abstracting the complexity of infrastructure resource access provisioning and orchestration,including discovery of data across distributed archives,away from the *** is needed because end-users wish to focus on analysing ready-to-use data products and models rather than spending their time on the setup and maintenance of complex and heterogeneous IT *** open federation will support processing and analysing the vast amounts of Copernicus and Earth Observation data that are critical for the implementation of the Destination Earth *** Twins vision for a high precision digital model of the Earth to model,monitor and simulate natural phenomena and related human activities.

关键词： Open compute and data federation big Earth data analytics federated data discovery federated access software distribution

The levels, sources and reactivity of volatile organic compounds in a typical urban area of Northeast China

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Journal of Environmental Sciences 2019年第5期31卷 121-134页

作者： Zhuobiao Ma Chengtang Liu Chenglong Zhang Pengfei Liu Can Ye Chaoyang Xue Di Zhao Jichen Sun Yiming Du Fahe Chai Yujing Mu Research Center for Eco-Environmental Sciences Chinese Academy of Sciences University of Chinese Academy of Sciences Center for Excellence in Regional Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences Shenyang Academy of Environmental Sciences Shenyang Environmental monitoring centre Chinese Research Academy of Environmental Sciences

Air concentrations of volatile organic compounds(VOCs) were continually measured at a monitoring site in Shenyang from 20 August to 16 September 2017. The average concentrations of alkanes, alkenes, aromatics and carbonyls were 28.54, 6.30, 5.59 and9.78 ppbv, respectively. Seven sources were identified by the Positive Matrix Factorization model based on the measurement data of VOCs and CO. Vehicle exhaust contributed the most(36.15%) to the total propene-equivalent concentration of the measured VOCs,followed by combustion emission(16.92%), vegetation emission and secondary formation(14.33%), solvent usage(10.59%), petrochemical industry emission(9.89%), petrol evaporation(6.28%), and liquefied petroleum gas(LPG) usage(5.84%). Vehicle exhaust, solvent usage and combustion emission were found to be the top three VOC sources for O_3 formation potential, accounting for 34.52%, 16.55% and 11.94%, respectively. The diurnal variation of the total VOCs from each source could be well explained by their emission characteristics,e.g., the two peaks of VOC concentrations from LPG usage were in line with the cooking times for breakfast and lunch. Wind rose plots of the VOCs from each source could reveal the possible distribution of the sources around the monitoring site. The O_3 pollution episodes during the measurement period were found to be coincident with the elevation of VOCs, which was mainly due to the air parcel from the southeast direction where petrochemical industry emission was found to be dominant, suggesting that the petrochemical industry emission from the southeast was probably a significant cause of O_3 pollution in Shenyang.

关键词： Volatile organic compounds Source apportionment Photochemical ozone formation Field measurement

Thermospheric neutral wind studies over the equatorial region:A review

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Earth and Planetary Physics 2025年第1期9卷 81-100页

作者： Siti Syazwani Nasuha Idahwati Sarudin Nurul Shazana Abdul Hamid Ahmad Fairuz Omar School of Physics Universiti Sains Malaysia11800 USMPulau PinangMalaysia Department of Applied Physics Faculty of Science and TechnologyUniversiti Kebangsaan Malaysia43600 UKM BangiSelangorMalaysia Space Science centre(ANGKASA) Institute of Climate ChangesUniversiti Kebangsaan Malaysia43600 UKM BangiSelangorMalaysia

Thermospheric neutral winds(TNWs)refer to the neutral gases in the thermosphere circulating as tides,which play a crucial role in the dynamics of the thermosphere-ionosphere system(TIS).Global geospace neutral winds,particularly over the magnetic equator,have been a subject of study for several ***,despite the known importance of neutral winds,a comprehensive understanding and characterization of the winds is still *** ground-based and satellite missions have provided valuable information on the contribution of neutral winds to the global atmospheric ***,efforts in the global monitoring of neutral winds are still lacking,and the drivers behind the behavior of TNWs as well as their influence on the TIS remain *** address these knowledge gaps in the global circulation of TNWs,it is crucial to develop a deep understanding of the neutral wind characteristics over different *** low-latitude equatorial region in particular has been observed to exert complex influences on TNWs because of the unique effects of the Earth’s magnetic field at the dip *** neutral winds over this region will provide valuable insights into the unique dynamics and processes that occur in this region,thereby enhancing our understanding of their role in the overall dynamics of the ***,through empirical observations,an improved ability to accurately model and predict the behavior of this region can be *** review article addresses challenges in understanding equatorial winds by reviewing historical measurements,current missions,and the interactions of ionospheric and thermospheric phenomena,emphasizing the need for comprehensive measurements to improve global atmospheric dynamics and weather forecasting.

关键词： thermospheric neutral wind thermosphere-ionosphere system dip equator equatorial region

A Privacy-Preserving Image Retrieval Based on AC-Coefficients and Color Histograms in Cloud Environment

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Computers, Materials & Continua 2019年第1期58卷 27-43页

作者： Zhihua Xia Lihua Lu Tong Qiu H.J.Shim Xianyi Chen Byeungwoo Jeon Jiangsu Engineering centre of Network monitoring Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment TechnologySchool of Computer and SoftwareNanjing University of Information Science&TechnologyNanjing210044China College of Information&Communication Engineering Sungkyunkwan UniversityKorea

Content based image retrieval(CBIR)techniques have been widely deployed in many applications for seeking the abundant information existed in *** to large amounts of storage and computational requirements of CBIR,outsourcing image search work to the cloud provider becomes a very attractive option for many owners with small ***,owing to the private content contained in images,directly outsourcing retrieval work to the cloud provider apparently bring about privacy problem,so the images should be protected carefully before *** paper presents a secure retrieval scheme for the encrypted images in the YUV color *** this scheme,the discrete cosine transform(DCT)is performed on the Y *** resulting DC coefficients are encrypted with stream cipher technology and the resulting AC coefficients as well as other two color components are encrypted with value permutation and position *** the image owner transmits the encrypted images to the cloud *** receiving a query trapdoor form on query user,the server extracts AC-coefficients histogram from the encrypted Y component and extracts two color histograms from the other two color *** similarity between query trapdoor and database image is measured by calculating the Manhattan distance of their respective ***,the encrypted images closest to the query image are returned to the query user.

关键词： Image retrieval AC-coefficients histogram color histogram discrete cosine transform

Intraspecific variation in shoot flammability in Dracophyllum rosmarinifolium is not predicted by habitat environmental conditions

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Forest Ecosystems 2022年第2期9卷 178-185页

作者： Xinglei Cui Adrian M.Paterson George LW.Perry Sarah V.Wyse Md Azharul Alam Congde Huang Shixing Zhou Lin Xiao Changhong Lai Fang He Dongyu Cao Kate Marshall Timothy J.Curran Department of Pest-management and Conservation Lincoln UniversityLincoln7647New Zealand National Forestry and Grassland Administration Engineering Research centre for Southwest Forest and Grassland Fire Ecological Prevention College of ForestrySichuan Agricultural UniversityChengdu611130China School of Environment University of AucklandAuckland1142New Zealand Bio-Protection Research centre Lincoln UniversityLincoln7647New Zealand Sichuan Province Forestry and Grassland Environmental monitoring centre Chengdu610036China

Background:Flammability is a compound plant trait that can vary significantly across natural populations within *** intraspecific variation in flammability provides insights into the evolution of plant flam-mability and inform understanding of wildfire risk and behaviour in different ***:We measured four flammability variables,representing ignitibility(time to ignition),sustainability(total burning time),combustibility(maximum temperature during burning)and consumability(percentage of biomass consumed by fire)to assess the shoot-level flammability of Dracophyllum rosmarinifolium(***.)(Ericaceae),a polymorphic endemic species distributed throughout New *** examined the relationship between flammability components and a suite of climatic and geographic variables(elevation,latitude,mean annual temperature(MAT),mean annual rainfall(MAR)of the sample locations,etc.).Results:We measured shoot-level flammability components of 62 individuals across eight *** time,maximum temperature and burnt biomass were positively correlated with each other,while ignition score was independent of other flammability *** flammability components varied significantly across the eight *** habitat conditions we considered were not related to any of the shoot-level flammability components of ***:Intraspecific variation in flammability in *** may be a byproduct of selection on other functional traits,such as leaf size,shoot lipid content,indicating that plant flammability is an incidental result,rather than selected for,at least in ecosystems without fire as a selective force.

关键词： Dracophyllum Fire Flammability Habitat

Near-field performance of chemical dissolution-front instability around a circular acid-injection-well in fluid-saturated porous media

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Science China(Technological Sciences) 2023年第7期66卷 2025-2035页

作者： ZHAO ChongBin HOBBS Bruce ORD Alison Computational Geosciences Research centre Central South UniversityChangsha 410083China Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment monitoring Ministry of EducationCentral South UniversityChangsha 410083China School of Earth and Environment University of Western AustraliaCrawleyWA 6009Australia

This paper investigates the near-field performance of chemical dissolution-front instability(CDFI) around a circular acidinjection-well in fluid-saturated porous media(FSPM) through using purely mathematical *** the mathematical governing equations of the CDFI problem involving radially divergent flow are briefly described,both analytical base solutions and perturbation solutions for the considered problem are mathematically *** analytical solutions lead to the theoretical expression of the perturbation induced dimensionless growth-rate and the following two new *** first new finding is that the critical Peclet number of a chemical dissolution system(CDS) associated with radially divergent flow in FSPM is not only a function of the permeability ratio between the undissolved and dissolved regions as well as the dimensionless wavenumber,but also a function of the circular chemical dissolution-front location relative to the circular acid-injection-well in *** second new finding is that as the direct result of considering a nonzero radius of the circular acid-injection-well,there exits a critical closeness number,which may be used to assess where the circular chemical dissolution-front starts becoming unstable in the CDS associated with radially divergent *** on these two new findings,a theoretical criterion of two parts has been *** first part of the established theoretical criterion answers the scientific question when a circular chemical dissolution-front can become unstable,while the second part of the established theoretical criterion answers the scientific question where a circular chemical dissolution-front can become *** applying the established theoretical criterion,a long-term existing mystery why the wormhole pattern of fractal nature and the compact pattern of fingering nature are formed at different locations away from the circular acid-injection-well circumference in fluid-saturated carbo

关键词： near-field performance circular injection well radially divergent flow analytical solutions dissolution-front instability porous media

Dynamic amplification factors for a system with multiple-degrees-of-freedom

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Earthquake Engineering and Engineering Vibration 2020年第2期19卷 363-375页

作者： Zhang Chao Hao Hong Bi Kaiming Yan Xueyuan College of Civil Engineering Fuzhou UniversityFuzhou 350108China centre for Infrastructure monitoring and Protection School of Civil and Mechanical EngineeringCurtin UniversityKent StreetBentley WA 6102Australia Key Laboratory of Urban Security and Disaster Engineering of MOE Beijing University of TechnologyBeijing 100124China

It is well-known that the responses of a structure are different when subjected to a static load or a sudden step *** dynamic amplification factor(DAF),which is defined as the ratio of the amplitude of the vibratory response to the static response,is normally used to depict the dynamic *** a single-degree-of-freedom system(SDOF)subjected to a sudden dynamic load,the maximum value of DAF is *** design guidelines therefore use 2 as an upper bound to consider the dynamic *** a civil engineering structure,which is normally a multiple-degrees-of-freedom(MDOF)system,the DAF may exceed 2 in certain *** adoption of 2 as the upper bond as suggested by the design guidelines therefore may lead to unsafe structural *** limited studies systematically investigate the DAF of a MDOF sysCorrespondence to:Bi Kaiming,centre for Infrastructure monitoring and Protection,School of Civil and Mechanical Engineering,Curtin University,Kent Street,Bentley WA 6102,Australia Tel:(+61)892665139 E-mail:***@*** study theoretically investigates the DAF of a MDOF system when it is subjected to a step load based on the fundamental theory of structural *** condition on which the DAF may exceed 2 is *** numerical examples and one experimental study of a cable-stayed bridge subjected to sudden cable loss are presented to illustrate the problem.

关键词： dynamic amplification factors(DAF) multiple-degrees-of-freedom(MDOF) step load