检索结果-南通市图书馆

钢渣粉低液固比固碳工艺及固碳钢渣粉对水泥基材料性能的影响

在线全文

学校读者我要写书评

暂无评论

材料导报 2024年第13期38卷 155-162页

作者：伍勇华匡玉峰易昂何娟原毅冰西安建筑科技大学材料科学与工程学院西安710055

矿物固碳进行CO_(2)捕集是减少温室效应的重要途径,钢铁生产企业利用钢渣与带有余热和CO_(2)的废气反应可以达到协同处置的效果。本工作研究了低液固比(润湿状态)条件下钢渣固碳的最佳工艺,确定出最佳固碳反应参数为反应温度100℃、液固... 详细信息

矿物固碳进行CO_(2)捕集是减少温室效应的重要途径,钢铁生产企业利用钢渣与带有余热和CO_(2)的废气反应可以达到协同处置的效果。本工作研究了低液固比(润湿状态)条件下钢渣固碳的最佳工艺,确定出最佳固碳反应参数为反应温度100℃、液固比9%、反应时间60 min、CO_(2)压力0.4 MPa。该工艺条件下,钢渣粉固碳率可达119.1 g CO_(2)/kg,固碳产物主要为方解石型碳酸钙。在此基础上,研究了掺入固碳钢渣粉对水泥净浆体积安定性、标准稠度需水量、凝结时间、胶砂强度和水化热的影响。结果表明:钢渣粉固碳后,体积安定性明显改善;固碳钢渣粉对水泥净浆标准稠度需水量无不利影响;与未固碳钢渣相比,固碳钢渣对水泥凝结硬化的延缓作用有所减弱,且随固碳率增大减弱效果增强;固碳钢渣粉在低掺量(10%)时,能提高水泥胶砂的3 d、7 d和28 d抗压强度,但掺量过高(>30%)时,会显著降低水泥胶砂的3 d、7 d和28 d抗压强度。XRD测试表明CaCO_(3)能够水化生成单碳型水化碳铝酸钙(C_(3)A·CaCO_(3)·11H_(2)O)和半碳型水化碳铝酸钙(C_(3)A·0.5CaCO_(3)·0.5Ca(OH)_(2)·11.5H_(2)O)。低液固比固碳有助于钢铁企业实现碳中和,也可以改善钢渣体积安定性,使钢渣粉得到更有效的利用。

关键词：钢渣矿物固碳固碳率体积安定性水化碳铝酸钙

基于CiteSpace的近十年国内外注意缺陷多动障碍认知功能的可视化分析

在线全文

学校读者我要写书评

暂无评论

中国儿童保健杂志 2024年第6期32卷 661-667,677页

作者：吴泳华于敬龙周康宁王俊宏北京中医药大学东直门医院北京100700

目的通过CiteSpace分析近十年国内外对注意缺陷多动障碍(ADHD)认知功能的研究现状、热点及发展趋势,为开展ADHD的后续研究提供借鉴和参考。方法运用CiteSpace软件检索Web Of Science(WOS)和CNKI、万方及维普数据库对近十年ADHD的认知功... 详细信息

目的通过CiteSpace分析近十年国内外对注意缺陷多动障碍(ADHD)认知功能的研究现状、热点及发展趋势,为开展ADHD的后续研究提供借鉴和参考。方法运用CiteSpace软件检索Web Of Science(WOS)和CNKI、万方及维普数据库对近十年ADHD的认知功能的相关文献,并进行文献计量学分析,对国家、机构和关键词等内容进行可视化展示。结果经筛选,共纳入2013—2022年文献4673篇,其中WOS文献4274篇,中文文献去重后共399篇,国际上发文量处于上升趋势,国内处于平稳发展状态;共纳入78个国家/地区、国外391所研究机构,以美国为代表的欧美国家的高等院校和医学中心发挥重要作用;纳入国内182所研究机构,主要以地区专科医院为主。国外关键词形成25个聚类标签;国内关键词形成8个聚类标签;国内分析共出现20个突现词;国外分析共出现25个突现词;关键词和聚类显示国内外该领域均以儿童或青少年为群体,关注ADHD共患病认知功能情况。国际上主要关注执行功能及其检测手段和基础研究方面;国内主要在干预疗效观察方面。研究重点和热点主要以生物学机制和临床研究为主。结论近十年对ADHD认知功能的研究,国际上研究更为全面和深入,国内目前处在平稳发展阶段,研究热点偏向不同,国内可借鉴国外发展经验,加大对神经生理学等基础研究的投入,并结果我国国情推进该领域的发展。

关键词：注意缺陷多动障碍认知功能 CiteSpace 研究热点

在线全文

学校读者我要写书评

暂无评论

基于重采样和混合集成学习的不平衡窃电检测

电网技术 2024年第2期48卷 730-739页

作者：游文霞梁皓杨楠李清清吴永华李文武三峡大学电气与新能源学院湖北省宜昌市443002 国网湖北省电力有限公司咸宁供电公司湖北省咸宁市437000 国网湖北省电力有限公司孝感供电公司湖北省孝感市432000

针对电力用户类别不平衡导致窃电检测具有偏向性问题,该文提出一种基于重采样和混合集成学习的不平衡窃电检测模型。首先以Easy-ensemble混合集成学习框架为基础确定最佳采样子集数;然后通过重采样自适应策略,即根据用户用电数据集的不... 详细信息

针对电力用户类别不平衡导致窃电检测具有偏向性问题,该文提出一种基于重采样和混合集成学习的不平衡窃电检测模型。首先以Easy-ensemble混合集成学习框架为基础确定最佳采样子集数;然后通过重采样自适应策略,即根据用户用电数据集的不平衡度以及最佳采样子集数确定检测模型的重采样方式,使用电数据达到平衡;最后按照先串行集成减小偏差、后并行集成降低方差的混合集成方式,对重采样后的均衡样本进行窃电检测。算例对比分析表明所提检测模型通过重采样和混合集成有效解决了传统集成算法在不平衡窃电检测中的偏向问题,降低了由于用电数据的不平衡性对集成结果的影响,提高了用户类别不平衡的窃电检测效果,在多种不平衡度下模型的准确率、F1值和G均值均表现优异。

关键词：窃电检测不平衡数据重采样集成学习 Easy-Ensemble集成框架

维普期刊数据库博看期刊

MOSSBAUER EFFECT STUDY OF YBa_(2)Cu_(3-x)Sn_(x)O_(7-y)SYSTEM

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1991年第8期4卷 139-142页

作者： WANG Genmiao ZHANG Han ZHANG Qirui wu yonghua Center of Structure and Element Analysis University of Science and Technology of China

Mssbauer spectra measurements reveal that Sn exists in YBa_2Cu_(3_x)Sn_xO_(7_y) system (x=0.05,0.10,0.20,0.30 and 0.40)in form of Sn^(4+) and occupies Cu(1)and Cu(2)*** relative rate at which Sn^(4+) occupies Cu(1)or Cu(2)sites varies with *** superconductivity transition temperature,T_c,depresses slightly due to the substitution of Cu for Sn.

关键词： Y-Ba-Cu-O system Mossbauer spectrum substitution superconductivity transition temperature

纳米C-S-H/PCE对蒸养UHPC力学性能增强机理研究

在线全文

学校读者我要写书评

暂无评论

硅酸盐通报 2024年第8期43卷 2797-2805页

作者：伍勇华易昂何娟匡玉峰原毅冰西安建筑科技大学材料科学与工程学院西安710055

目前超高性能混凝土(UHPC)制品的力学性能有待进一步提升,采用纳米C-S-H/PCE对UHPC进行增强在理论上是一种可行的技术途径。本文研究了蒸养条件下掺入以聚羧酸(PCE)为分散剂的纳米水化硅酸钙(C-S-H/PCE)对UHPC力学性能的影响,通过测试... 详细信息

目前超高性能混凝土(UHPC)制品的力学性能有待进一步提升,采用纳米C-S-H/PCE对UHPC进行增强在理论上是一种可行的技术途径。本文研究了蒸养条件下掺入以聚羧酸(PCE)为分散剂的纳米水化硅酸钙(C-S-H/PCE)对UHPC力学性能的影响,通过测试水化热、水化产物、微观形貌和孔结构等对其机理进行了分析。结果表明,掺入3.0%(质量分数)纳米C-S-H/PCE可以显著提高蒸养UHPC的抗压强度和抗折强度。掺入纳米C-S-H/PCE可以促进UHPC的早期水化,生成更多的水化硅酸钙(C-S-H)凝胶,使水化放热温峰增高,并缩短达到水化温峰的时间。掺入纳米C-S-H/PCE可有效改善蒸养UHPC的孔结构,在掺量为3.0%(质量分数)时总孔隙率最小,有害孔比例最低。该研究可为纳米C-S-H/PCE在蒸养UHPC中的应用提供参考。

关键词：纳米C-S-H/PCE 超高性能混凝土孔结构水化放热蒸汽养护

维普期刊数据库博看期刊

Upper mantle SH velocity structure beneath Qiangtang Terrane by modeling triplicated phases

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2008年第20期53卷 3211-3218页

作者： ZHANG RuiQing wu QingJu LI yonghua ZENG RongSheng Institute of Geophysics China Earthquake Administration Beijing 100081 China

我们嘘由比较地区性的距离在西方的 Qiangtang 岩层下面为上面的披风抑制波浪速度结构有合成震动图的地震 triplicated 波形，基于中介，事件(∼220 km ) 由 INDEPTH-III 地震数组记录了。ATIP 模型揭示一个低速度的异例与直到在在在上... 详细信息

我们嘘由比较地区性的距离在西方的 Qiangtang 岩层下面为上面的披风抑制波浪速度结构有合成震动图的地震 triplicated 波形，基于中介，事件(∼220 km ) 由 INDEPTH-III 地震数组记录了。ATIP 模型揭示一个低速度的异例与直到在在在上面的披风的 410 km 的深度上面的 190 270 km 和一个相对小的速度坡度的深度的 −4% 变化，它与以前的结果一致。在有另外的地质的研究的联合，我们建议最高的岩流圈的深度是 190 km，变瘦的大规模岩石圈都不发生在西方的 Qiangtang 岩层，除以外， Qiangtang 岩层作为稳定的欧亚大陆有一样的有点上面的披风结构。

关键词：剪切速度结构三重相转变带上地幔岩层西藏高原

Characteristics of Surface Solar Radiation under Different Air Pollution Conditions over Nanjing, China: Observation and Simulation

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2019年第10期36卷 1047-1059页

作者： Hao LUO Yong HAN Chunsong LU Jun YANG yonghua wu Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration School of Atmospheric Physics Nanjing University of Information Science and Technology Nanjing 210044 China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies School of Atmospheric Sciences Sun Yat-sen University Guangzhou 510275 China State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China NOAA-CREST City College of the City University of New York New York 10031 USA

Surface solar radiation (SSR) can affect climate, the hydrological cycle, plant photosynthesis, and solar power. The values of solar radiation at the surface reflect the influence of human activity on radiative climate and environmental effects, so it is a key parameter in the evaluation of climate change and air pollution due to anthropogenic disturbances. This study presents the characteristics of the SSR variation in Nanjing, China, from March 2016 to June 2017, using a combined set of pyranometer and pyrheliometer observations. The SSR seasonal variation and statistical properties are investigated and characterized under different air pollution levels and visibilities. We discuss seasonal variations in visibility, air quality index (AQI), particulate matter (PM10 and PM2.5), and their correlations with SSR. The scattering of solar radiation by particulate matter varies significantly with particle size. Compared with the particulate matter with aerodynamic diameter between 2.5 μm and 10 μm (PM2.5-10), we found that the PM2.5 dominates the variation of scattered radiation due to the differences of single-scattering albedo and phase function. Because of the correlation between PM2.5 and SSR, it is an effective and direct method to estimate PM2.5 by the value of SSR, or vice versa to obtain the SSR by the value of PM2.5. Under clear-sky conditions (clearness index ≥0.5), the visibility is negatively correlated with the diffuse fraction, AQI, PM10, and PM2.5, and their correlation coefficients are ?0.50,?0.60,?0.76, and ?0.92, respectively. The results indicate the linkage between scattered radiation and air quality through the value of visibility.

关键词： surface solar radiation air pollution particulate matter visibility radiative transfer

A preliminary study on thermoluminescence characteristics of sediments from the North Pacific

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2007年第3期26卷 56-72页

作者： LU Huahua SHI Xuefa wu yonghua YANG Gang WEI Jianwei REN Xiangwen Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Key Laboratory of Marine Sedimentology and Environmental Geology First Institute of Oceanography State Oceanic Administration Qingdao 260061 China Graduate School Chinese Academy of Sciences Beijing 100049 China

Thirty-eight surficial deposit samples were collected from the equatorial North Pacific, and the natural thermoluminescence （TL） characteristics of both bulk and clay fraction samples （〈 2μm fractions） were studied by the FJ427 - AI automatic TL Dosimeter for the first time. With the measurements of clay mineral composition, element composition by XRD and ICP, the correlations between TL intensity and sedimentary environment proxies were analyzed, such as water depth, ratio of FeO to Fe2 O3 contents, LOI, and major clay mineral concentration, and it was found the bulk sample＇ s TL signal was stronger than the clay ones. Usually, increase in the clay components may result in the decrease of TL intensity. From the shape of TL curves, the pelagic sediments can be divided into two groups： the majority group has two glow peaks, in general, the first peak is broad and flat, but the second narrow and sharp; the minority group only has a single peak because the first is absent. The peak centers of TL curves are almost fixed, falling in the temperature sections 230 ~ 260 and 390 ~ 405℃ respectively. Lorentz model packed in the Origin 7.5 was chosen to deal with the TL curves. From the processing results, three parameters （H, C and A ） , corresponding to the height, center, and kurtosis of TL curve, were obtained to describe the curve characteristics. The correlations between TL curve parameters and sedimentary environment proxies were also calculated. On the basis of the above work, the relationship between TL characteristics and sediment type, mineral composition, sedimentary environment of surface sediments was discussed in the study area, and a conclusion is： sediments from the environment of shallower water, higher organic contents and weaker reductivity have stronger TL signals.

关键词： North Pacific surface sediments thermoluminescence sedimentary environment clay minerals

Rock magnetic property of gravity core CSH1 from the northern Okinawa Trough and the effect of early diagenesis

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2007年第5期26卷 54-65页

作者： GE Shulan SHI Xuefa wu yonghua LEE Tehquei XIONG Yingqian SAITO Yoshiki Marine Sedimentation and Environmental Geology Key Laboratory of State Oceanic Administration First Institute of Oceanography State Oceanic Administration Qingdao 266061 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Earth Sciences Taipei China Geology Survey of Japan Tsukuba 306 - 8567 Japan

Detailed rock magnetic investigations were undertaken at 2 -4 cm interval for the gravity core CSHI （with a length of 17.36 m） from the northern Okinawa Trough. Time-scale of the core was constructed by two characteristic tephras and foraminferal assemblages, indicating an age of 50 ka for the bottom of the core. Except for three tephras and abrupt decrease in surface, there are little changes in all kinds of rock magnetic parameters that can be correlated to the climate change for the last 50 ka. Different from the common sediments, most S-ratios （S equals the negative ratio of IRM-0.3T to SIRM, which is an indicator of low coercivity content） of the sediments are smaller than 0. 9, which implies a substantial amount of magnetic minerals with high coercivity. The existence of iron sulphide （ greigite or pyrrhotite） is revealed by representative susceptibility - temperature curves showing 200 350 ℃ Curie temperature in addition to 580 ℃ of magnetite, and also by awful smell during heating and dark heating products. Both the occurrence of authigenic iron sulphide and quick decrease of magnetic parameters near the surface clearly show that sediments from Core CSHI have undergone early diagenesis. The featureless magnetic changes of the whole core except for three tephras mean that the post-depositonal alteration is so strong that most original signals have been destroyed. For the same reason, the organic matter in sediment and sulphate in pore water must have been consumed along with dissolution, precipitation of iron and manganese happening sequencially during the redox reaction series. Great caution must be taken when using these altered chemical parameters for the interpretation of climatic changes.

关键词： northern Okinawa Trough gravity core of CSHI rock magnetic property characteristic tephra early diagenesis