检索结果-南通市图书馆

Synthesis and Flocculation of Polyacrylamide with Low Water Absorption for Non-dispersible Underwater Concrete

Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1404-1413页

作者： LI Hongling YAN Na sun guowen ZHENG Haorui YANG Xinyu Depantment of Chemistry and Miaterials Engineering Xinxiang Normal CollegeXinxiang 453003China School of Materials Science and Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China Hebei Key Laboratory of Advanced Materials for Transportation Engineering and Environment Shijiazhuang 050043China

The polyacrylamide which is directly added into concrete shows strong water absorption property.Thus the construction of underwater constructure would demand high amount of water,resulting in poor workability of concrete and strength shrinkage after hardening.Herein,a kind of anionic polyacrylamide(APAM)grafted with water reducing functional group(-COOH)was synthesized at low temperatures by partial factor design and response surface design.The structure and morphology of APAM were characterized by UV,FTIR and SEM methods.The experimental results show that the molecular weight of the synthesized APAM could reach 11 million,under the condition that the temperature was 35℃,the pH value was 8,the monomer concentration was 27wt%,the initiator dosage was 0.6wt%,and the monomer ratio(n(AM):n(AA))was 3.When the APAM was applied into the underwater slurry,it presented good flocculation and low water demand.When the dosage was 1%of the mass of the cement,the water demand increased by 12%,which could meet the self-leveling and anti-dispersity of the underwater slurry at the same time.This technology provides technical guidance for the large-scale industrial production of polyacrylamide for underwater concrete construction while achieving environmental protection during production.

关键词： non-dispersible underwater concrete anionic polyacrylamide partial factor design response surfacedesign flocculation

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

Internal Curing Mechanism of Sepiolite in Cement Paste

引用

Journal of Wuhan University of Technology(Materials Science) 2023年第4期38卷 857-864页

作者：许晨席王彩辉 LI Wenhao sun Kaili ZHANG Guangxing sun guowen KONG Lijuan Hebei Key Laboratory of New Materials for Collaborative Development of Traffic Engineering and Environment Shijiazhuang050043China China State Construction Technical Center Beijing101300China China Railway 18th Bureau Group Co.Ltd Tianjin300222China

In order to explore the internal curing mechanism of sepiolite in cement-based materials,the effects of sepiolite on the water consumption of standard consistency,setting time,viscosity,strength,pore structure characteristics,micro-hardness characteristics and two-dimensional surface characteristics of cement paste were studied,respectively.The experimental results show that the water consumption of standard consistency increases linearly with the increase of sepiolite content.The setting time and viscosity are also lengthened and increased with the addition of sepiolite,respectively.When the content of sepiolite exceeds 5%,the strength of the specimen increases significantly.The BET results show that the pore structure of the interfacial transition zone(ITZ)in hardened cement paste(HCP)with sepiolite is optimized after curing for28 d and its pore volume content with below 10 nm is decreased,especially for the specimen with a lower watercement ratio.The characteristics of microhardness and strength of specimens have the same law.Backscattered electron image(BSE-IA)shows that the ITZ of the specimen with sepiolite is denser and the unhydrated cement particles are less than the reference specimen.

关键词： sepiolite cement paste internal curing

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

Transient Damping of Virtual Synchronous Generator for Enhancing Synchronization Stability during Voltage Dips

引用

CES Transactions on Electrical Machines and Systems 2024年第2期8卷 143-151页

作者： Shitao sun Yu Lei guowen Hao Yi Lu Jindong Liu Zhaoxin Song Jie Zhang North China Electric Power Research Institute Co. Ltd. State Grid Xinyuan Co. Ltd. Hebei Fengning Pumped Storage Energy Co. Ltd.

Virtual synchronous generators(VSGs) are widely introduced to the renewable power generation, the variablespeed pumped storage units, and so on, as a promising gridforming solution. It is noted that VSGs can provide virtual inertia for frequency support, but the larger inertia would worsen the synchronization stability, referring to keeping synchronization with the grid during voltage dips. Thus, this paper presents a transient damping method of VSGs for enhancing the synchronization stability during voltage dips. It is revealed that the loss of synchronization(LOS) of VSGs always accompanies with the positive frequency deviation and the damping is the key factor to remove LOS when the equilibrium point exists. In order to enhance synchronization stability during voltage dips, the transient damping is proposed, which is generated by the frequency deviation in active power loop. Additionally, the proposed method can realize seamless switching between normal state and grid fault. Moreover, detailed control design for transient damping gain is given to ensure the synchronization stability under different inertia requirements during voltage dips. Finally, the experimental results are presented to validate the analysis and the effectiveness of the improved transient damping method.

关键词： Damping Voltage fluctuations Control design Switches Power system stability Stability analysis Synchronous generators

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Quantitative Calculation of Hydration Products for Binary Slag-Portland Cement System

引用

Journal of Wuhan University of Technology(Materials Science) 2014年第5期29卷 972-979页

作者：蒋金洋 sun guowen sun Wei Jiangsu Key Laboratory of Construction Materials Southeast University School of Materials Science and Engineering Shijiazhuang Tiedao University

The reaction models and the quantitative calculation on the volume fraction of hydration products for binary ground granulated blast-furnace slag （GGBFS） cement system are presented, in which two important factors are taken into account, i e, the reactivity of GGBFS influenced by its chemical compositions and the partial replacement of aluminum phase in calcium silicate hydrate （C-S-H） gel. A simplified treatment is further suggested towards the quantification. In particular, when the replacement level of GGBFS is lower than 70%, the ratio of calcium over silica （C/S） is set at 1.5 or at 1.2 otherwise. The validity of the proposed model is addressed in terms of the contents of calcium Portlandite and non-evaporable water.

关键词： Portland cement GGBFS reaction model hydration product

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

Numerical calculation and influencing factors of the volume fraction of interfacial transition zone in concrete

引用

Science China(Technological Sciences) 2012年第6期55卷 1515-1522页

作者： sun guowen sun Wei ZHANG YunSheng LIU ZhiYong Jiangsu Key Laboratory of Construction Materials Southeast UniversityNanjing 211189China

The determination of volume fraction of interfacial transition zone(ITZ) is very important for investigating the quantitative relationship between the microstructure and macroscopical property of concrete.In this paper,based on Lu and Torquato's most nearest surface distribution function,a calculating process of volume fraction of ITZ is given in detail according to the actual sieve curve in concrete.Then,quantitative formulas are put forward to measure the influencing factors on the ITZ volume fraction.In order to validate the given model,the volume fractions of ITZ obtained by numerical calculation are compared with those by computer simulation.The results show that the two are in good agreement.The order of the factors influencing the ITZ volume fraction is the ITZ thickness,the volume fraction of aggregate and the maximum aggregate diameter for Fuller gradation in turn.The ITZ volume fraction obtained from the equal volume fraction(EVF) gradation is always larger than that from the Fuller gradation for a given volume fraction of aggregate.

关键词：界面过渡区体积分数影响因素数值计算计算机模拟大骨料定量关系微观结构

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

应用颊脂垫联合邻近软组织瓣修复老年大型口腔上颌窦瘘

引用

口腔医学研究 2024年第4期40卷 321-324页

作者：徐泽东孙国文南京大学医学院附属口腔医院南京市口腔医院口腔颌面外科江苏南京210008

目的:评价应用颊脂垫瓣联合邻近软组织瓣,同期修补由骨髓炎或肿瘤切除术中造成的老年大型口腔上颌窦瘘的临床效果。方法:收集南京大学医学院附属口腔医院口腔颌面外科2020年1月~2022年12月收治的术中并发大型(最大直径大于4 cm)口腔上... 详细信息

目的:评价应用颊脂垫瓣联合邻近软组织瓣,同期修补由骨髓炎或肿瘤切除术中造成的老年大型口腔上颌窦瘘的临床效果。方法:收集南京大学医学院附属口腔医院口腔颌面外科2020年1月~2022年12月收治的术中并发大型(最大直径大于4 cm)口腔上颌窦瘘患者8例,患者年龄62~84岁。回顾性分析应用颊脂垫瓣联合颊侧推进瓣或腭黏膜瓣覆盖缺损,术后随访对疗效进行评估。结果:全部病例修复成功,未见软组织瓣坏死、穿孔、感染及上颌窦炎鼻窦炎,随访3个月颌面部基本对称,经张口训练后,张口度恢复正常。结论:颊脂垫瓣联合邻近软组织瓣是方便可靠的修复老年大型口腔上颌窦瘘方法,值得临床推广。

关键词：老年口腔上颌窦瘘颊脂垫邻近软组织瓣

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

DeepLabV3_DHC:城市无人机遥感图像语义分割

引用

激光与光电子学进展 2024年第4期61卷 384-393页

作者：孙国文罗小波张坤强重庆邮电大学计算机科学与技术学院重庆空间大数据智能技术工程研究中心重庆400065 昆明理工大学信息工程与自动化学院云南昆明650500

高分辨率无人机遥感图像具有极为丰富的语义和地物特征,在语义分割中容易出现目标分割不全、边缘信息缺失、分割精度不足等问题。为了解决上述问题,基于DeepLabV3_plus模型提出改进的DeepLabV3_DHC。首先,利用多种主干网络进行下采样,... 详细信息

高分辨率无人机遥感图像具有极为丰富的语义和地物特征,在语义分割中容易出现目标分割不全、边缘信息缺失、分割精度不足等问题。为了解决上述问题,基于DeepLabV3_plus模型提出改进的DeepLabV3_DHC。首先,利用多种主干网络进行下采样,采集图像的低级特征和高级特征。其次,将原模型的atrous spatial pyramid pooling(ASPP)全部替换成深度可分离混合空洞卷积,同时添加自适应系数,减弱网格效应。之后,抛弃传统上采样的双线性插值法,替换为可学习的密集上采样卷积。最后,在低级特征中串联注意机制。选用多种主干网络进行实验,数据集选用四川省隆昌市地区的部分图像,采用平均交并比和类别平均像素准确率作为评价指标。实验结果表明:所提方法不仅具有较高的分割精度,而且减少了计算量和参数量。

关键词：城市无人机遥感图像语义分割深度可分离混合空洞卷积密集上采样注意力机制网格效应

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

Investigation of the Interfacial Transition Zone between Aggregate-Cement Paste by AC Impedance Spectroscopy

引用

Journal of Wuhan University of Technology(Materials Science) 2016年第4期31卷 865-871页

作者：孔丽娟 hou lirong wang yuhua sun guowen School of Materials Science and Engineering Shijiazhuang Tiedao University Shijiazhuang 050043 China

Three different types and sizes of coarse aggregate were chosen,and the alternating current（AC） impedance of cement paste samples with and without aggregate was measured at different curing ages.Based on Song’s equivalent circuit model,the electrical properties from the AC impedance results were obtained,and the resistance of connected pores RCCP was used to characterize the microstructure of the interfacial transition zone（ITZ）.The results show that the RCCP of concrete sample with aggregate is lower than that of cement paste sample,which indicates that the introduction of aggregate in cement paste makes the ITZ porous.Furthermore,for the same type of aggregate,an increase in particle size leads to a more porous ITZ,which accounts for the “water effect” and a larger aggregate would accumulate a thicker water film around it.In addition,for the same size of aggregate,the physical interaction between aggregate and cement paste is dominant in early age,and the microstructure of the ITZ around limestone aggregate is denser,which mainly depends on its rough surface and high water absorption.However,the microstructures of the ITZ around granite and basalt aggregates are denser in later age,which may be due to their higher chemical activity,and the chemical interaction between them and cement paste resulting in the generation of more hydrates.AC impedance spectroscopy thus proves to be powerful for evaluation of the microstructure of the ITZ.

关键词： aggregate paste impedance hydration curing Paste limestone sizes characterize porous

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

以数智化赋能绿色电力证书一体化管控研究思考

引用

能源科技 2024年第2期22卷 65-69页

作者：孙国文国家能源集团电力营销中心有限公司北京100034

为顺利实现我国“双碳”目标,构建以新能源为主体的新型电力系统是关键举措,绿色电力证书(绿证)是体现可再生能源绿色价值的重要凭证。国家能源集团绿证管理面临责任主体众多、信息壁垒较厚、收益分配困难、数智化手段匮乏等问题,无法... 详细信息

为顺利实现我国“双碳”目标,构建以新能源为主体的新型电力系统是关键举措,绿色电力证书(绿证)是体现可再生能源绿色价值的重要凭证。国家能源集团绿证管理面临责任主体众多、信息壁垒较厚、收益分配困难、数智化手段匮乏等问题,无法最大化兑现绿证的环境价值。从绿证核发、需求侧、供应侧、数据治理、价格机制等方面建立一体化管控体系,并通过数智化手段,打造绿证全过程线上管理平台,为各市场主体购销绿证提供服务和支撑,最终实现国家能源集团绿证购销效益最大化。

关键词：绿色电力证书数智化价值机制可再生能源

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

Effect of Friction Reclaimed Materials of Waste Brake-shoe on Basic Performance of Mortar

引用

Journal of Wuhan University of Technology(Materials Science) 2017年第3期32卷 603-610页

作者：王彩辉 HUANG Dongjie FU Hua WU Hongya QIN Guoqiang sun guowen GUO Na School of Materials Science and Engineering Shijiazhuang Tiedao University He Bei Provincial Key Laboratory of Traffic Engineering Materials China Southern Railway (CSR) Group SHIJIAZHUANG Corporation Limited School of Postgraduates

Discarded train brake shoes mainly consist of steel-backed friction material. To be better reutilized, its essential features and its interaction in cement-based material need to be studied. Consequently, particle size analysis, SEM, IR and TGA were used to investigate two types of waste brake shoes, i e, mechanical grinding friction reclaimed material of waste brake-shoe（G-FRMWBS） and pyrolysis-friction reclaimed materials of waste brake-shoe（P-FRMWBS）. The latter exhibited less organic content, larger range of particle size distribution and smaller medium particle diameter. Both types contained inorganic particles of spherical and irregular shapes, striped with steel fiber. Upon isometric substituting fine aggregates, G-FRMWBS lifted the strength of mortar effectively that was increased by 16.6% and 17.5% when the replacing rate was 5%; the value went up to 19.2% and 19.2% when the replacing rate was 10%. Moreover, inclusion of FRMWBS enhanced the chloride penetration resistance, and optimized the pore characteristic and ITZ（interfacial transition zone） as well.

关键词： friction reclaimed materials of waste brake-shoe mortar strength porosity ITZ

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：