检索结果-南通市图书馆

Rapid estimation of soil heavy metal nickel content based on optimized screening of near-infrared spectral bands

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geochimica 2020年第1期39卷 116-126页

作者： Qian Lu Shijie wang Xiaoyong Bai Fang Liu Shiqi Tian Mingming wang jinfeng wang State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of Sciences99 Lincheng West RoadGuiyang 550081Guizhou ProvincePeople's Republic of China College of Resource and Environment Guizhou UniversityGuiyang 550000China

In near-infrared spectroscopy,the traditional feature band extraction method has certain ***,a band extraction method named the three-step extraction method was *** method combines characteristic absorption bands and correlation coefficients to select characteristic bands corresponding to various spectral forms and then uses stepwise regression to eliminate meaningless *** least squares regression(PLSR)and extreme learning machine(ELM)models were used to verify the effect of the band extraction *** show that the differential transformation of the spectrum can effectively improve the correlation between the spectrum and nickel(Ni)*** correlation coefficients were above 0.7 and approximately 20%higher than those of other transformation *** model effect established by the feature variable selection method based on comprehensive spectral transformation is only slightly affected by the spectral transformation *** types of spectral transformation,the RPD values of the proposed method were all within the same *** RPD values of the PLSR model were concentrated between 1.6 and 1.8,and those of the ELM model were between 2.5 and2.9,indicating that this method is beneficial for extracting more complete spectral *** combination of the three-step extraction method and ELM algorithm can effectively retain important bands associated with the Ni content of the *** model based on the spectral band selected by the three-step extraction method has better prediction ability than the other *** ELM model of the first-order differential transformation has the best prediction accuracy(RP^2=0.923,RPD=3.634).The research results provide some technical support for monitoring heavy metal content spectrum in local soils.

关键词： Heavy metal Band extraction Partial least squares regression Extreme learning machine Near infrared spectroscopy

Hyperspectral estimation model of soil Pb content and its applicability in different soil types

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2020年第3期39卷 423-433页

作者： Shiqi Tian Shijie wang Xiaoyong Bai Dequan Zhou Qian Lu Mingming wang jinfeng wang School of Geography and Environmental Sciences Guizhou Normal UniversityGuiyang 550081Guizhou ProvincePeople’s Republic of China State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of Sciences99 Lincheng West RoadGuiyang 550081Guizhou ProvincePeople’s Republic of China Puding Karst Ecosystem Observation and Research Station Chinese Academy of SciencesPuding 562100Guizhou ProvincePeople's Republic of China

In order to obtain Pb content in soil quickly and efficiently,a multivariate linear regression(MLR) and a principal component regression(PCR) Pb content estimation model were established on the basis of hyperspectral techniques,and their applicability in different soil types was *** indicated that Pb exhibited strong spatial heterogeneity in the study area,and more than 82% of the samples exceeded the background *** addition,the pollution range was *** was sensitive in the nearinfrared band,and the correlation of absorbance(AB) was most significant of all the transformed *** models achieved optimal stability and reliability when AB was used as an independent *** with the PCR model,the stability,fitting accuracy,and predictive power of the MLR model were superior with a coefficient of determination,root mean square error,and mean relative error of 0.724%,24.92%,and 28.22%,*** models could be applied to different soil types;however,MLR had better applicability compared with *** PCR model that distinguished different soil types had better reliability than one that did ***,the model established via hyperspectral techniques can achieve largearea,rapid,and efficient soil Pb content monitoring,which can provide technical support for the treatment of heavy metal pollution in soil.

关键词： Hyperspectral data Heavy metal Pb.Estimation

Optimization design and experiment on ripple surface type pickup finger of precision maize seed metering device

在线全文

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2017年第1期10卷 61-71页

作者： wang Jinwu Tang Han wang jinfeng Li Xin Huang Huinan College of Engineering Northeast Agricultural UniversityHarbin 150030China

A ripple surface type pickup finger was designed to improve the performance of pickup finger precision maize seed metering device and to provide a solution for precision maize *** main structure and working principle of seed metering device were detailed in this *** dimension size distributions of maize seeds in different types were studied,the gestures of seeds clamped by pickup finger were analyzed,and the clamping dynamical model of pickup finger was established by theoretical *** optimize the structural parameters of ripple surface type pickup finger,the discrete element method(DEM)model of pickup finger precision maize seed metering device was established by the discrete element software *** numerical simulations of orthogonal seeding performance experiments were conducted to analyze the influences of these factors on the quality of *** rotational speed,wavelength of ripple surface and amplitude of ripple surface were selected as the experimental *** average seeding qualified index and the average seeding coefficient of variation on four different types of maize seeds were chosen for evaluating the seeding *** results showed that,the average seeding qualified index was 93.35%and the average seeding coefficient of variation was 11.23%under conditions of the 25 r/min rotational speed,8 mm wavelength of ripple surface and 2 mm amplitude of ripple *** the same condition,the bench test was done which showed that the results of test and simulation were *** maximum error of qualified index was 1.95%and the qualified index of improved seed metering device exceeded the original one by 12.34%.The working performance can meet the requirements of precision maize seeding.

关键词： precision maize planter seed metering device pickup finger ripple surface

Splitting positive definite mixed element method for viscoelasticity wave equation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2012年第4期7卷 725-742页

作者： Yang LIU Hong LI Wei GAO Siriguleng HE jinfeng wang School of Mathematical Sciences Inner Mongolia University Hohhot 010021 China School of Statistics and Mathematics Inner Mongolia Finance and Economics College Hohhot 010051 China

A splitting positive definite mixed finite element method is proposed for second-order viscoelasticity wave equation. The proposed procedure can be split into three independent symmetric positive definite integro-differential sub-system and does not need to solve a coupled system of equations. Error estimates are derived for both semidiscrete and fully discrete schemes. The existence and uniqueness for semidiscrete scheme are proved. Finally, a numerical example is provided to illustrate the efficiency of the method.

关键词： Viscoelasticity wave equation transformation splitting positive definite system mixed finite element method error estimate

Measurement and analysis of restitution coefficient between maize seed and soil based on high-speed photography

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2017年第3期10卷 102-114页

作者： wang Jinwu Tang Han wang jinfeng Jiang Dongxuan Li Xin College of Engineering Northeast Agricultural UniversityHarbin 150030China

The restitution coefficient is an important elementary physical parameter related to the research and development of agricultural *** kinematic model of maize seed in the falling and impacting processes was developed to measure the restitution coefficient between maize seed and soil.A test bench for measuring the restitution coefficient was designed and built referred to the theory of mirror *** velocities for impacting maize seed were measured and analyzed in a three-dimensional space via high-speed photography,and then restitution coefficients of in different impact conditions were *** this basis,this study took flat dent seed and round seed as *** factor tests were conducted to analyze the influences of these factors on the restitution *** impact angle,falling height,soil compaction,soil moisture,maize moisture content and different parts of seed were selected as test *** corresponding regression equations were obtained by *** results showed that,as the impact angle was bigger than 25°,the restitution coefficient increased with the increase of impact *** restitution coefficient had a linear decreasing trend with the increase of falling *** the soil compaction strength was 200-350 kPa,the restitution coefficient increased with the increase of soil *** the soil compaction strength was larger than 350 kPa,the changing trend of the restitution coefficient was relatively *** the soil moisture content was 13.5%-18%,the restitution coefficient decreased with the increase of soil *** the soil moisture content was 18%,the restitution coefficient was the *** the maize moisture content was 11%-16%,the restitution coefficient decreased with the increase of maize moisture *** rotational motion always occurred in falling process of flat dent seed and round *** probabilities of crown part and lateral part of maize seed impacting with soil were the highest

关键词： maize seed soil restitution coefficient mirror reflection high-speed photography measurement

江西省R&D经费投入的特征分析及提升对策研究

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

科技广场 2024年第2期 68-74页

作者：梅丁丁王金凤童金杰卢婷江西省科学技术信息研究所江西南昌330046

本文分析近年来江西省R&D经费投入的特征及问题,研究表明:江西省R&D经费投入总量和强度均保持较快增长,但还存在投入总量规模不大、结构不优、财政资金投入相对较少等问题,并从强化企业创新主体地位、加大财政资金支持力度、提升科技金... 详细信息

本文分析近年来江西省R&D经费投入的特征及问题,研究表明:江西省R&D经费投入总量和强度均保持较快增长,但还存在投入总量规模不大、结构不优、财政资金投入相对较少等问题,并从强化企业创新主体地位、加大财政资金支持力度、提升科技金融支持研发创新以及提升科技统计质量等方面提出了对策建议,为江西省提升全社会研发投入水平,加快创新型省份建设提供了决策参考。

关键词：科技统计 R&D投入创新型省份

Calibrations of Urbanization Level in China

在线全文

学校读者我要写书评

暂无评论

China CDC weekly 2022年第6期4卷 111-115页

作者： Yang wang jinfeng wang Yansui Liu Jie Li State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina Center for Regional Agriculture and Rural Development Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijingChina

Urbanization is the inevitable outcome of socioeconomic development,especially after the industrial revolution in 1760(1).Since the founding of the People’s Republic of China in 1949,the urbanization of China has made great *** speed and mass of urbanization and notably its relevant consequences,such as resource consumption and carbon emissions,has taken place in the most populous country in the world over the past three decades,which is raising increased concerns internationally(2)(Figure 1).Urbanization rate(in this article,this indicator refers to the population urbanization rate)is a common indicator of *** international organizations(such as the World Bank,World Health Organization,Food and Agriculture Organization of the United Nations,etc.)use urbanization as one of the important criteria for measuring productivity and economic growth in a country(1).China’s urbanization process can be described as the largest population migration in history and has also had an important impact on public *** the national population migrates from rural to urban areas,differences in lifestyle,environmental quality,social security,and accidental injuries have all been brought about and become more and more dramatic(3).

关键词： Urbanization Figure founding

磁共振脂肪定量技术分析腹腔内脏脂肪含量与2型糖尿病关系的Meta分析

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

现代医学 2024年第5期52卷 687-694页

作者：王金凤王海静罗琳陈强原小军内蒙古科技大学包头医学院内蒙古包头014010 内蒙古科技大学包头医学院第一附属医院医学影像科内蒙古包头014010

目的:基于Meta分析评估磁共振脂肪定量技术在腹腔内脏脂肪含量与2型糖尿病(T2DM)关系中的效能,进而探讨以腹腔内脏脂肪含量预测T2DM发病的可行性。方法:检索PubMed、Embase、The Cochrane Library、知网和万方数据库自1995年1月1日至202... 详细信息

目的:基于Meta分析评估磁共振脂肪定量技术在腹腔内脏脂肪含量与2型糖尿病(T2DM)关系中的效能,进而探讨以腹腔内脏脂肪含量预测T2DM发病的可行性。方法:检索PubMed、Embase、The Cochrane Library、知网和万方数据库自1995年1月1日至2023年3月31日关于腹腔内脏脂肪与T2DM关系的中英文文献,依据纳入及排除标准独立筛选文献、提取数据并进行质量评估。最后采用STATA 12.0软件进行统计分析并绘制森林图。采用亚组分析的方法寻找异质性来源,绘制漏斗图以评估是否存在发表偏倚。结果:共纳入16篇文献。共1814例受试者,其中T2DM组759例,健康对照(HC)组1055例。T2DM患者的胰腺及肝脏异位脂肪沉积含量高于健康人群,且腹腔内脏脂肪含量亦高于健康人群。T2DM组患者的胰腺脂肪分数(PFF)[加权均数差(WMD)=2.71,95%CI 2.01~3.41]、肝脏脂肪分数(HFF)(WMD=6.03,95%CI 4.10~7.95)、腹腔内脏脂肪面积(VFA)(WMD=77.71,95%CI 39.98~115.43)及皮下脂肪组织面积(SFA)(WMD=27.72,95%CI 6.76~48.69)均大于HC组,且组间差异有统计学意义(P<0.01)。结论:T2DM患者的腹腔内脏脂肪组织、皮下脂肪组织、肝脏及胰腺脂肪含量明显高于健康人群。磁共振脂肪定量技术为定量测量腹腔内脏脂肪及异位脂肪沉积提供了一种有效的无创性方法指标,在未来用于脂肪定量科研中具有较大的发展前景。

关键词： 2型糖尿病脂肪核磁共振 Meta分析

贵金属载量对油电混合动力汽车尾气污染物排放特性的影响研究

在线全文

学校读者我要写书评

暂无评论

小型内燃机与车辆技术 2024年第4期53卷 49-54页

作者：李大成王金凤孙创王燕刘志敏王云中自环保科技股份有限公司四川成都611731

以某2.0T油电混合动力汽车的尾气排放特征和减排效果为研究重点,设计了同一系列不同Pd、Rh含量的三效催化剂,并对该系列催化剂老化前后的起燃性能、空燃比窗口特性以及WLTC循环的整车排放性能进行了测试。原始排放测试结果表明,该车型... 详细信息

以某2.0T油电混合动力汽车的尾气排放特征和减排效果为研究重点,设计了同一系列不同Pd、Rh含量的三效催化剂,并对该系列催化剂老化前后的起燃性能、空燃比窗口特性以及WLTC循环的整车排放性能进行了测试。原始排放测试结果表明,该车型排气温度在300~560℃,相对于燃油车,排气温度低,空燃比偏大,混合气整体偏稀燃;冷起动阶段,THC和NOx排放控制较难。引入该系列催化剂后,该车型的排放测试结果表明,催化剂的起燃性能与催化剂贵金属总含量呈线性关系;贵金属含量增加,能使污染物快速达到完全转化。新鲜催化剂的整车排放测试结果表明,THC和NOx的整车排放受贵金属总含量的影响比CO大。由催化剂老化后的整车排放测试结果可以看出,催化剂中,Pd含量对THC的整车排放影响较大,而Rh含量对NOx的整车排放影响较大;CO的整车排放受贵金属总含量的影响较小,当贵金属总含量超过2.21 g时,CO的整车排放基本相同。研究结果能够为油电混合动力汽车三效催化剂的研发和贵金属减量研究提供参考。

关键词：油电混合动力汽车三效催化剂贵金属含量 WLTC循环排放发动机台架