检索结果-南通市图书馆

Leakage detection of oil tank using terahertz spectroscopy

Science China(Technological Sciences) 2021年第9期64卷 1947-1952页

作者： QIN FanKai CHEN SiTong CHEN Ru ZHAN HongLei miao XinYang XIANG WenFeng ZHAO kun College of New Energy and Materials China University of PetroleumBeijing 102249China Beijing Key Laboratory of Optical Detection Technology for Oil and Gas China University of PetroleumBeijing 102249China Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection Petroleum and Chemical Industry FederationChina University of PetroleumBeijing 102249China Detection and Beijing Key Laboratory of Failure Corrosionand Protection of Oil/Gas FacilitiesChina University of PetroleumBeijing 102249China

The necessity for safety in oil-gas storage and transportation has led to increasing technical requirements for on-line monitoring of damaged pores and oil leakage from tanks. In this study, the severity of damage of the oil tank at the micron level was detected by terahertz time-domain spectroscopy(THz-TDS), which is of great significance for the early detection and prevention of oil leakage. The THz amplitude(EP) was related to the severity of damaged according to the THz-TDS measurement of oil tanks with various degrees of damage, including intact, partially damaged, completely damaged, and seriously damaged *** and scattering effects co-occurred when the THz wave penetrated the tanks, with the collective tendencies being used to expressly monitor oil leakage from tanks. When the oil tank was damaged to form micron-level pores and the crude oil had not overflowed, the pore size was close to THz wavelength and the Mie scattering effect was obvious. After further destruction of the pores, the crude oil gradually spilled over and the scattering effect was gradually transformed from Mie scattering to Rayleigh scattering. In addition, the polar molecules in crude oil have strong resonance under the irradiation of THz wave, and the THz wave has strong attenuation. Eventually, surface tension of the oil flattens the surface of the tank, the scattering effect is gradually suppressed and replaced by the absorption effect. Absorption and scattering caused by THz waves passing through tanks coexist and have competing relationships. The change rule of EPcan successfully prove the phenomenon and can be considered as an important alternative for application to predict the degree of tank damage. Therefore, in this study, the detection of pores as small as micrometers on the oil tank was expected to greatly prevent oil leakage accidents and improve the safety of oil and gas storage and transportation.

关键词： absorption scattering terahertz spectroscopy oil tank leakage

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Visualization of Two-dimensional Single Chains of Hybrid Polyelectrolytes on Solid Surface

引用

Chinese Journal of Polymer Science 2021年第6期39卷 716-724,I0006页

作者： Lan-Lan Zhang Wen-Ke miao Li-Jun Ren Yu-kun Yan Wei Wang Center for Synthetic Soft Materials Key Laboratory of Functional Polymer Materials of the Ministry of Education and Institute of Polymer ChemistryCollege of ChemistryNankai UniversityTianjin 300071China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Nankai UniversityTianjin 300071China

The polyacidic character of polyoxometalate(POM)clusters endows high ionic conductivity,making these clusters good candidates for solar and fuel *** bonding of clusters to polymer chains creates poly(POM)s that are polyelectrolytes with both cluster functions and polymer ***,solution-processable poly(POM)s are expected to be used as key materials in advanced *** understanding of poly(POM)s will optimize the preparation process and improve device ***,we report a study of the first linear poly(POM)s by directly visualizing the chains using scanning transmission electron *** with traditional polymers,individual clusters of poly(POM)s can be directly visualized because of the resistance to electron-beam damage and the high contrast of the tungsten POM ***,cluster aggregates with diverse shapes were *** the number of clusters in the aggregates allowed the degree of polymerization and molecular weight distribution to be determined,and studying the aggregate shapes revealed the presence of a curved semirigid chain in *** study of shape diversity revealed that strong interactions between clusters determine the diverse chain shapes formed during solution *** insight is critical to understanding the formation of poly(POM)films from solutions as key functional materials,especially for fuel and solar cells.

关键词： Polyelectrolyte Polyacidic cluster Functional hybrid Chain Scanning transmission electron microscopy

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

CSLabel： An Approach for Labelling Mobile App Reviews

引用

Journal of Computer Science & Technology 2017年第6期32卷 1076-1089页

作者： Li Zhang Xin-Yue Huang jing Jiang Ya-kun Hu State Key Laboratory of Software Development Environment Beihang University Beijing 100191 China

Mobile apps （applications） have become a popular form of software, and the app reviews by users have become an important feedback resource. Users may raise some issues in their reviews when they use apps, such as a functional bug, a network lag, or a request for a feature. Understanding these issues can help developers to focus on users＇ concerns, and help users to evaluate similar apps for download or purchase. However, we do not know which types of issues are raised in a review. Moreover, the amount of user reviews is huge and the nature of the reviews＇ text is unstructured and informal. In this paper, we analyze 3 902 user reviews from 11 mobile apps in a Chinese app store -- 360 Mobile Assistant, and uncover 17 issue types. Then, we propose an approach CSLabel that can label user reviews based on the raised issue types. CSLabel uses a cost-sensitive learning method to mitigate the effects of the imbalanced data, and optimizes the setting of the support vector machine （SVM） classifier＇s kernel function. Results show that CSLabel can correctly label reviews with the precision of 66.5%, the recall of 69.8%, and the F1 measure of 69.8%. In comparison with the state-of-the-art approach, CSLabel improves the precision by 14%, the recall by 30%, the F1 measure by 22%. Finally, we apply our approach to two real scenarios： 1） we provide an overview of 1 076 786 user reviews from 1 100 apps in the 360 Mobile Assistant and 2） we find that some issue types have a negative correlation with users＇ evaluation of apps.

关键词： mobile app user review classification

来源：

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

The effect of oxidation on physicochemical properties and aqueous stabilization of multiwalled carbon nanotubes：comparison of multiple analysis methods

引用

Science China Chemistry 2016年第11期59卷 1498-1507页

作者： Luqing Zhang Minhao Wang jing Fang kun Yang Daohui Lin Department of Environmental Science Zhejiang UniversityHangzhou 310058China School of Environmental Science and Engineering Zhejiang Gongshang UniversityHangzhou 310012China Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control Zhejiang UniversityHangzhou 310058China

Surface oxidation can alter physicochemical properties of multiwalled carbon nanotubes(MWCNTs) and influence their aqueous *** techniques have been used to characterize the physicochemical properties and aqueous stabilization of ***,the relationship between the change in physicochemical property and the aqueous stabilization of MWCNTs merits more studies,and the multiple characterization techniques have not been well *** study systematically and comparatively investigated the effect of oxidation on the physicochemical properties and aqueous stabilization of MWCNTs using multiple analysis *** surface area,disclosed tube ends,defects on the sidewalls,disruption of the electronic structure,and removal of metal catalysts and amorphous carbon were observed for the oxidized MWCNTs(o-MWCNTs) using the multipoint Brunauer-Emmett-Teller(BET) method,transmission electron microscope observation,Raman spectroscopy,UV-Vis spectroscopy,and thermogravimetric *** oxidation-time-dependent increase in oxygen content of the MWCNTs was verified by the methods of elemental analysis,mass difference calculation,and X-ray photoelectron spectroscopy(XPS).Fourier transform infrared spectroscopy,XPS,and the Boehm titration were employed to study the functionalities on the MWCNT *** the limitations of these techniques,the results indicated that the dramatic increase in carboxyl groups was mainly responsible for the significant increase in oxygen content after the *** dissociation of the grafted functional groups increased electronegativity of the o-MWCNTs and facilitated the aqueous stabilization of o-MWCNTs through electrostatic *** oxidation affected the UV-Vis absorbance of MWCNT *** absorbances at 800 nm of the stabilized MWCNT suspensions had a good correlation with the MWCNT concentrations and could be used to quantify the MWCNT *** findings of this work are expected to boo

关键词： carbon nanomaterials acid treatment characterization techniques colloidal behavior

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Comparison of Two Methods to Assess the Size Structure of Phytoplankton Community Assemblages, in Liaodong Bay, China

引用

Journal of Ocean University of China 2019年第5期18卷 1207-1215页

作者： SONG Lun WU jing DU jing LI Nan WANG kun WANG Peng State Key Laboratory of Urban Water Resource and Environment School of EnvironmentHarbin Institute of TechnologyHaerbin 150090China Key Laboratory of Marine Biological Resources and Ecology Liaoning Ocean and Fisheries Science Research Institute Dalian 116023China

Liaodong Bay is one of the largest semi-enclosed bays located in Bohai Sea,in northeast *** is an important feeding and spawning place,even wintering and breeding migration base for many marine *** size structure of phytoplankton communities is a key feature of marine ecosystems and can be used as an indicator for algae disaster,but the methods to evalute is still ***,we compared the size-fractionated chlorophyll-a method with a high-throughout sequencing method in an evaluation of the size structure of phytoplankton assemblages in Liaodong Bay,China,in *** proportion of picophytoplankton was estimated at just 19%according to the results based on size-fractionated chlorophyll-a,which likely represents a severe *** sequencing method confirmed that many kinds of phytoplankton species appeared in more than one size-fractionated filter membrane,with some even dominating where the filter membrane pore size was greater than the individual phytoplankton *** to the sequencing method,the phytoplankton assemblages in Liaodong Bay were dominated by picophytoplankton(average proportion=44%),followed by the nanophytoplankton(average 32%),a composition that is more consistent with other *** sequencing method provides a more robust way to assess the size structure and taxonomic diversity of marine phytoplankton communities.

关键词： size structure chlorophyll-a high-throughout sequencing Liaodong Bay

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Risk assessment of heavy metal contaminated soil in the vicinity of a lead/zinc mine

引用

Journal of Environmental Sciences 2005年第6期17卷 881-885页

作者： LI jing XIE Zheng-miao ZHU Yong-guan Ravi Naidu Institute for Soil and Water Resources and Environment Zhejiang University Hangzhou 310029 China Research Centre for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Centre for Environmental Risk Assessment and Remediation University of South Australia Mawson Lakes SA 5095 Australia

Heavy metal contamination of soils through anthropogenic activities is a widespread and serious problem confronting scientists and regulators throughout the world. In this study we investigated the distribution, chemical species and availability of lead, zinc, cadmium and copper in nine surface（0 to 20 cm） soils from near an abandoned lead/zinc mine tailings located in Shaoxing, Zhejiang, China. Total heavy metal contents ranged from 5271 to 16369 mg/kg for Pb, 387 to 1221 mg/kg for Zn, 3.0 to 9.3 mg/kg for Cd and 65 to 206 mg/kg for Cu. In general, all heavy metals exceeded China National Standards for Soil Environmental Quality of Heavy Metals by a factor of 3-65 times. Comparison of the heavy metal concentrations（Pb, Zn, Cd and Cu） with clay content revealed a strongly significant relationship while significant relationship（ P 〈 0.001 ） was also obtained between Cd ＋ Zn and Pb ＋ Cu. Solid phase speciation of the soils using Tessier procedure showed that the heavy metals were distributed in the order： residual 〉〉 organically complexed-Fe-Mn oxides occluded 〉 carbonate bound 〉 exchangeable 〉 water soluble. In the organic matter fraction, the ratio of Pb（29.1% ） to its total concentration in the soils was higher than those of Zn（4.70% ）, Cd（3.16% ） and Cu（9.50% ）. The percentages of the water soluble and the exchangeable fractions of Pb（1.80% ） and Cd（2.74% ） were markedly greater than those of Zn（0.10% ） and Cu（0.15% ）, suggesting that Pb and Cd are relatively more mobile and hence more toxic in the contaminated soils. Strongly significant relationships between H20-Pb, H20-Zn and H20-Cu, strong positive correlations between H20-Pb, H20-Zn, H20-Cu and organic matter in soil were found. The content of H20-Pb, H20-Zn, H20-Cu was negatively correlated with pH values. The similar negative relationships between pH values and exchangeable heavy metals were also recorded. It is suggested that increasing soil pH or liming the soil could decrease bioavailability of heavy met

关键词： fractionation heavy metal mining tailings risk assessment soil pollution

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Nonparametric estimation for contamination distribution

引用

Applied Mathematics(A Journal of Chinese Universities) 2008年第2期23卷 175-182页

作者： HUI Jun miao Bai-qi NING jing PENG Heng Dept. of Statist. and Finance Univ. of Sci. and Tech. of China Hefei 230026 China Dept. of Math. Hefei Univ. of Tech. Hefei 230009 China

In the paper, for the contamination distribution model F（x） = （1-α）F1（x）＋αF2（x）, the estimates of α and F1 （x） are studied using two different ways when F2 （x） is known and the strong consistency of th... 详细信息

关键词： contamination distribution strong consistency rate of consistency.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Target versus sub-target dose of renin–angiotensin system inhibitors on survival in elderly patients with heart failure with reduced ejection fraction: a systematic review and meta-analysis

引用

Journal of Geriatric Cardiology 2023年第6期20卷 469-478页

作者： Long-kun SUN jing KONG Xiao-Wei YANG jing WANG Peng-Fei ZHANG The Key Laboratory of Cardiovascular Remodeling and Function Research Chinese Ministry of EducationChinese National Health Commission and Chinese Academy of Medical SciencesThe State and Shandong Province Joint Key Laboratory of Translational Cardiovascular MedicineDepartment of CardiologyQilu HospitalCheeloo College of MedicineShandong UniversityJinanChina

BACKGROUND The efficiency of the target versus sub-target dose of renin–angiotensin system inhibitors(RASIs)in elderly patients with heart failure(HF)with reduced ejection fraction(HErEF)remains *** PubMed,Embase,and the Cochrane Central Register of Controlled Trials were searched from database inception through March 2022 for randomized controlled trials(RCTs)and observational studies considering the effect of the target versus sub-target dose of RASIs on survival in elderly patients(≥60 years)with *** primary outcome was all-cause *** secondary outcomes were cardiac mortality,HF hospitalization,and the composite endpoint of mortality or HF hospitalization.A meta-analysis was conducted to generate combined hazard ratio(HR)and 95%*** Seven studies(two RCTs and five observational studies)enrolling 16,634 patients were included.A pooled analysis suggested that the target versus sub-target dose of RASIs led to lower rates of all-cause mortality(HR=0.92,95%CI:0.87–0.98,I2=21%)and cardiac mortality(HR=0.93,95%CI:0.85–1.00,I2=15%)but not reduced rates of HF hospitalization(HR=0.94,95%CI:0.88–1.01,I2=0)and the composite endpoint(HR=1.03,95%CI:0.91–1.15,I2=51%).However,the target dose of RASIs was associated with a similar primary outcome(HR=0.85,95%CI:0.64–1.14,I2=0)in a subgroup of very elderly patients>75 years of *** Our analysis suggests that the target dose of RASIs has a better survival benefit in elderly patients with HFrEF compared to the sub-target dose of ***,the sub-target dose of RASIs is associated with a similar mortality rate in very elderly patients>75 years of *** high-quality and adequately powered RCTs are warranted.

关键词： patients analysis fraction

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Efficient construction of calcium fluoride nanoaggregates for enhanced water vapor adsorption

引用

Particuology 2024年第6期89卷 191-197页

作者： Dan-Lei Yang jing Cao Rong-kun Liu Jie-Xin Wang School of Life Sciences and Chemical Engineering Jiangsu Second Normal UniversityNanjing210013China State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing100029China Petrochemical Research Institute PetroChinaBeijing102206China

Calcium fluoride(CaF_(2))is an ideal adsorbent for the dehydration of gaseous hydrogen fluoride(HF)containing water *** this work,a novel CaF_(2)absorbent,spherical CaF_(2)nanoaggregates(NAs)with a closely packed structure,was proposed and efficiently fabricated by spray drying *** the building blocks of CaF_(2)NAs,the CaF_(2)nanoparticles(NPs)were prepared by the addition of excess calcium ions(Ca^(2+))or fluorine ions(F−)in the *** results indicated that the CaF_(2)NPs synthesized by excess Ca^(2+)and the corresponding NAs exhibited much better water vapor adsorption properties than their counterparts by excess F−,owing to higher zeta *** importantly,whether excess Ca^(2+)or F^(−),CaF_(2)NAs had further enhanced water vapor adsorption capacity compared to primary CaF_(2)NPs,possibly owing to their unique nano-micro secondary structures and higher surface *** work has great potential in the development of high-performance absorbents for separating moisture from corrosive gas HF.

关键词： CaF_(2)nanoaggregates Water vapor adsorption Spray drying

来源：

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

A giant central red disk galaxy at redshift z=0.76:Challenge to theories of galaxy formation

引用

Science China(Physics,Mechanics & Astronomy) 2021年第7期64卷 137-141页

作者： kun Xu ChengZe Liu YiPeng jing Marcin Sawicki Stephen Gwyn Department of Astronomy School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai200240China Tsung-Dao Lee Institute Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghai200240China Canada Research Chair Department of Astronomy&Physics and the Institute for Computational AstrophysicsSaint Mary’s UniversityHalifaxB3H 3C3Canada NRC-Herzberg Astronomy and Astrophysics National Research Council of CanadaVictoriaV9E 2E7Canada

We report a giant red central disk galaxy in the XMM-LSS north region. The region is covered with a rich variety of multi-band photometric and spectroscopic observations. Using the photometric data of the Canada-France-Hawaii Telescope Legacy Survey(CFHTLS) and spectroscopic observation of the baryon oscillation spectroscopic survey(BOSS), we find that the galaxy has a stellar mass of ~1011.6 M⊙. The galaxy has a red color and has an old stellar population, and thus its star formation has *** the photometric image data of the Hyper Suprime-Cam(HSC) Subaru Strategic Program, we demonstrate that its luminosity profile is perfectly described by a Sérsic form with n=1.22 consistent with that of a disk. We also analyze its environment based on the VIMOS Public Extragalactic Redshift Survey(VIPERS) photometric catalog, and find that its close neighbors are all less massive, indicating that our observed galaxy is sitting at the center of its dark matter host halo. Existence of such a giant red central disk galaxy seriously challenges the current standard paradigm of galaxy formation, as there is no known physical mechanism to explain the quenching of its star formation. This conclusion is supported by state-of-the-art hydrodynamical simulations of galaxy formation.

关键词： disk galaxies galaxy quenching massive galaxies

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：