检索结果-南通市图书馆

基于磨齿机床在线测量系统的探头标定方法研究

在线全文

学校读者我要写书评

暂无评论

制造技术与机床 2017年第11期 28-31页

作者：汪中厚徐阐刘欣荣王冰青曹欢马雅鹤上海理工大学机械工程学院上海200093

基于在线测量机床系统误差提出一种测量探头的高精度标定方法。选用标准量棒作为标定参考,首先测量量棒同一截面位置上的不同点来获取测量数据,然后根据最小二乘法对测量数据进行测量圆拟合,最后将拟合圆心坐标进行几何处理,得到测量探... 详细信息

基于在线测量机床系统误差提出一种测量探头的高精度标定方法。选用标准量棒作为标定参考,首先测量量棒同一截面位置上的不同点来获取测量数据,然后根据最小二乘法对测量数据进行测量圆拟合,最后将拟合圆心坐标进行几何处理,得到测量探头中心坐标。该标定方法简单有效、适用范围广,可有效解决标定时探头自由度较少的问题,为测量仪上探头的标定提供参考。

关键词：在线测量探头标定最小二乘法测量圆拟合

耕作方式和秸秆还田对砂姜黑土碳库及玉米小麦产量的影响

在线全文

学校读者我要写书评

暂无评论

农业工程学报 2019年第14期35卷 112-118页

作者：叶新新王冰清刘少君马超李军利柴如山熊启中李虹颖郜红建安徽农业大学资源与环境学院农田生态保育与污染防控安徽省重点实验室合肥230036 安徽省农业科学院土壤肥料研究所合肥230001

长期秸秆还田免耕覆盖措施导致沿淮区域砂姜黑土耕层变浅、下表层(10~30cm)容重增加、土壤养分不均衡等问题凸显,限制了小麦-玉米周年生产力的提高。耕作和秸秆还田措施合理的搭配组合是解决这一问题的有效方法。通过8年的小麦-玉米一... 详细信息

长期秸秆还田免耕覆盖措施导致沿淮区域砂姜黑土耕层变浅、下表层(10~30cm)容重增加、土壤养分不均衡等问题凸显,限制了小麦-玉米周年生产力的提高。耕作和秸秆还田措施合理的搭配组合是解决这一问题的有效方法。通过8年的小麦-玉米一年两熟田间试验,设置4个处理:1)玉米季免耕-小麦季免耕秸秆不还田(N);2)玉米季深耕-小麦季深耕秸秆不还田(D);3)玉米季秸秆免耕覆盖还田+小麦秸秆免耕覆盖还田(NS);4)玉米季秸秆免耕覆盖还田+小麦季秸秆深耕还田(DS)。通过分析作物收获后不同土壤深度(0~60cm)总有机碳(TOC)、颗粒态碳(POC)、微生物生物量碳(MBC)、易氧化态碳(KMnO4-C)、可溶性有机碳(DOC)和土壤碳库管理指数(CPMI),并结合小麦-玉米的周年产量变化,以期获得培肥砂姜黑土的最佳模式。研究结果表明:1)相对于长期免耕措施(N),DS处理能够提高0~30cm土层TOC、POC、MBC、KMnO4-C等组分含量和CPMI;而NS措施仅提高土壤表层(0~10cm)TOC、活性有机碳组分含量和CPMI;2)DS处理显著提升了小麦-玉米的周年生产力,其麦玉的周年产量均值分别比N、D和NS处理高出14.7%、12.9%和8.5%;3)MBC和KMnO4-C对于耕作和秸秆还田措施都是较为敏感指示因子。总的来说,玉米季小麦秸秆覆盖还田+小麦季玉米秸秆深耕还田(DS)是改善沿淮地区砂姜黑土土壤碳库、提高小麦-玉米周年产量的一种有效农田管理模式。

关键词：作物耕作秸秆土壤碳库作物产量

Application of FTIR two-dimensional correlation spectroscopy(2D-COS)analysis in characterizing environmental behaviors of microplastics:A systematic review

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2025年第1期147卷 200-216页

作者： Shuang Peng Feipeng wang Dongbin Wei Cuiping wang Haijun Ma Yuguo Du Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China North Minzu University Yinchuan 750001China

Microplastics(MPs)are ubiquitous in the environment,continuously undergo aging processes and release toxic chemical *** the environmental behaviors of MPs is critical to accurately evaluate their long-term ecological *** twodimensional correlation spectroscopy(2D-COS)is a powerful tool for MPs studies,which can dig more comprehensive information hiding in the conventional one-dimensional spectra,such as infrared(IR)and Raman *** recent applications of 2D-COS in analyzing the behaviors and fates of MPs in the environment,including their aging processes,and interactions with natural organicmatter(NOM)or other chemical substances,were summarized *** main requirements and limitations of current approaches for exploring these processes are discussed,and the corresponding strategies to address these limitations and drawbacks are proposed as ***,new trends of 2D-COS are prospected for analyzing the properties and behaviors of MPs in both natural and artificial environmental processes.

关键词： Microplastics(MPs) 2D-COS application Aging processes Interactions

Adsorption of typical NDMA precursors by superfine powdered activated carbon:Critical role of particle size reduction

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2025年第1期147卷 101-113页

作者： Ying wang Zhichen Zhang Zhihang Yin Jun wang Xiaojian Zhang Chao Chen State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Research Institute for Environmental Innovation(Suzhou) TsinghuaSuzhou 215163China

Control of N-nitrosodimethylamine(NDMA)in drinking water could be achieved by removing its precursors as one practical ***,superfine powdered activated carbons with a diameter of about 1μm(SPACs)were successfully prepared by grinding powdered activated carbon(PAC,D50=24.3μm)and applied to remove model NDMA precursors,***(RAN)and nizatidine(NIZ).Results fromgrain diameter experiments demonstrated that the absorption velocity increased dramatically with decreasing particle size,and the maximum increase in k2 was 26.8-folds for RAN and 33.4-folds for ***,kinetic experiments explained that rapid absorption could be attributed to the acceleration of intraparticle diffusion due to the shortening of the diffusion ***,performance comparison experiments suggested that the removal of RAN and NIZ(C_(0)=0.5 mg/L)could reach 61.3%and 60%,respectively,within 5 min,when the dosage of SAPC-1.1(D_(50)=1.1μm)was merely 5 mg/L,while PAC-24.3 could only eliminate 17.5%and 18.6%.The adsorption isotherm was well defined by Langmuir isotherm model,indicating that the adsorption of RAN/NIZ was a monolayer coverage *** adsorption of RAN or NIZ by SAPC-1.1 and PAC-24.3 was strongly pH dependent,and high adsorption capacity could be observed under the condition of pH>pk_(a)+*** coexistence of humic acid(HA)had no significant effect on the adsorption performance because RAN/NIZ may be coupled with HA and removed *** coexistence of anions had little effect on the adsorption *** study is expected to provide an alternative strategy for drinking water safety triggered by NDMA.

关键词： Adsorption NDMA Kinetics Superfine powdered activated carbon Intraparticle diffusion Drinking water

Mercury contents and potential exposure risk of rice-containing food products

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2025年第2期148卷 683-690页

作者： Xin wang Yingjun wang Yaqi Zhang Ziyan Liu Xiaomeng Ji Yong Cai Shandong Key Laboratory of Environmental Processes and Health School of Environmental Science and EngineeringShandong UniversityQingdao 266237China Department of Chemistry&Biochemistry Florida International UniversityMiamiFL 33199USA

Mercury(Hg),especially methylmercury(MeHg),accumulation in rice grain due to rice paddy possessing conditions conducive to Hg methylation has led to human Hg exposure through consumption of rice-based daily *** addition to being a food staple,rice is widely used as a raw material to produce a vast variety of processed food *** is known about Hg levels in snacking rice-food products and potential Hg exposure from consumption of them,besides previous studies on infant rice *** to provide complementary information for a more complete assessment on Hg exposure risk originated from Hgcontaining rice,this study determined total Hg(THg)and MeHg levels in 195 rice-containing and rice-free processed food products covering all major types of snack foods marketed in China and the estimated daily intake(EDI)of dietary Hg from the consumption of these *** results clearly showed THg and MeHg contents in rice-containing foods were significantly higher than rice-free products,suggesting the transfer of Hg and MeHg from the rice to the end products,even after manufacturing ***,significant positive correlations were observed between THg,MeHg,or MeHg/THg ratio and rice content for samples containing multiple grains as ingredients,further indicating the deciding role of rice for Hg levels in the end food *** the EDI of THg and MeHg via ricebased food products were relatively low compared to the reference dose,it should be considered these snacking food products would contribute additive Hg intake outside of the daily regular meals.

关键词： Mercury Methylmercury Processed food products Rice Dietary exposure

Wafer‑Scale Vertical 1D GaN Nanorods/2D MoS_(2)/PEDOT:PSS for Piezophototronic Effect‑Enhanced Self‑Powered Flexible Photodetectors

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano-Micro Letters 2025年第3期17卷 102-116页

作者： Xin Tang Hongsheng Jiang Zhengliang Lin Xuan wang Wenliang wang Guoqiang Li State Key Laboratory of Luminescent Materials and Devices South China University of TechnologyGuangzhou 510640People’s Republic of China Department of Electronic Materials School of Materials Science and EngineeringSouth China University of TechnologyGuangzhou 510640People’s Republic of China

van der Waals(vdW)heterostructures constructed by lowdimensional(0D,1D,and 2D)materials are emerging as one of the most appealing systems in next-generation flexible ***,hand-stacked vdW-type photodetectors are not compatible with large-areaarray fabrication and show unimpressive performance in self-powered ***,vertical 1D GaN nanorods arrays(NRAs)/2D MoS_(2)/PEDOT:PSS in wafer scale have been proposed for self-powered flexible photodetectors arrays *** as-integrated device without external bias under weak UV illumination exhibits a competitive responsivity of 1.47 A W^(−1)and a high detectivity of 1.2×10^(11)Jones,as well as a fast response speed of 54/71μs,thanks to the strong light absorption of GaN NRAs and the efficient photogenerated carrier separation in type-II ***,the strain-tunable photodetection performances of device have been ***,the device at−0.78%strain and zero bias reveals a significantly enhanced photoresponse with a responsivity of 2.47 A W^(−1),a detectivity of 2.6×10^(11)Jones,and response times of 40/45μs,which are superior to the state-of-the-art self-powered flexible *** work presents a valuable avenue to prepare tunable vdWs heterostructures for self-powered flexible photodetection,which performs well in flexible sensors.

关键词： Vertical nanorod arrays van der Waals heterostructure Piezophototronic effect Self-powered photodetection Flexible sensors

Performance analysis of two-way relay mixed RF/FSO system with co-channel interference

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2025年第2期21卷 85-89页

作者： wang Zhuo School of Optoelectronic Engineering Changchun University of Science and TechnologyChangchun 130022China

In this paper,the performance of a two-way relay (TWR) mixed radio frequency/free space optical (RF/FSO) system with co-channel interference (CCI) is *** from interference-limited one-way relay (OWR) system,CCIs should be considered at both relay and users in TWR ***,opportunistic user schedule is applied to select the user with the largest signal to interference plus noise ratio (SINR).Exact and asymptotic outage probability (OP) is *** bit error rate (BER) is further presented to evaluate the overall *** results show that the performance of a TWR system is dominated by the uplink or downlink whose performance is severer.

关键词： FSO channel system

Spatiotemporal evolution of wildfire activity during the Paleocene-Eocene Thermal Maximum in China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2025年第2期68卷 509-522页

作者： Xue-Ting wang Zuoling CHEN Linlin CUI Xu wang State Key Laboratory of Lithospheric and Environmental Coevolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences College of Earth and Planetary SciencesBeijing 100049China Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China

The Paleocene-Eocene Thermal Maximum(PETM)was the most prominent warming event in the Cenozoic and serves as a geological analog for the current global warming driven by anthropogenic CO_(2)emissions from burning fossil *** a primary disruptor of Earth's ecosystems,wildfire activity affects the balance of ecosystems,the global carbon cycle,and climate ***,studying the evolution and driving mechanisms of wildfires during the PETM is essential for predicting wildfire activity under global warming scenarios and for understanding the carbon cycle in the context of wildfire *** research on wildfires during the PETM has mainly focused on the Northern Hemisphere,particularly Europe and North America,whereas studies on Chinese mainland remain *** this study,we analyzed black carbon(BC)concentration and carbon isotope(δ13C)in the Beigou section of the Nanyang Basin and the Xilutian section of the Fushun Basin to reconstruct the spatiotemporal evolution of wildfires in arid/semi-arid and humid *** integrated these findings with those of previous studies on the paleoclimate of the research area to elucidate the driving mechanisms behind wildfire *** results indicate that wildfire activity weakened at the onset of the PETM,with the negative carbon isotope period characterized by low wildfire activity,except for a brief resurgence in the Nanyang *** the recovery phase of the PETM,wildfire activity gradually increased,returning to the pre-PETM *** prolonged low wildfire state was likely caused by extremely high temperatures and precipitation as well as the resulting vegetation *** the PETM recovery phase,increased wildfire activity transformed“short-term carbon sinks”of the biological-atmospheric carbon cycle into“long-term carbon sinks”through the burial of *** process of carbon sink conversion may have acted as a negative feedback mechanism,contributing to carbon sequestration and the e

关键词： PETM Wildfire Carbon cycle Nanyang Basin Fushun Basin

同方期刊数据库

Photoinduced radical sulfur dioxide insertion with asymmetric cyclization of alkenes:accessingβ-chiral sulfones bearing S-stereocentric cyclic sulfinamides

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1期68卷 257-263页

作者： Jiapian Huang Chenxin wang Xu wang Xiaoyu Zhou Wei Xiao Jie Wu School of Pharmaceutical and Chemical Engineering&Institute for Advanced Studies Taizhou UniversityTaizhou 318000China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang 453007China

The generation of variousβ-chiral sulfones bearing chiral cyclic sulfinamides through photoredox-catalyzed sulfur dioxide insertion with asymmetric radical cyclization is *** method features a broad substrate scope and excellent *** studies reveal that the dispersion interaction between sulfinyl group and CH_(2)SO_(2)Ph group plays a crucial role in the stereoselectivity control.

关键词： β-chiral sulfones chiral cyclic sulfinamides sulfur dioxide insertion asymmetric radical cyclization stereoselectivity