资源类型

期刊论文 1172

会议视频 40

会议信息 2

年份

2024 4

2023 80

2022 102

2021 114

2020 83

2019 93

2018 77

2017 102

2016 87

2015 80

2014 33

2013 47

2012 40

2011 30

2010 38

2009 37

2008 26

2007 24

2006 20

2005 11

展开 ︾

关键词

发展战略 17

能源 9

2035年 6

可持续发展 6

智能制造 6

中国航天 5

技术预见 5

2023全球十大工程成就 4

“走出去” 4

中国铁路“走出去” 4

发展 4

2035 3

S-N曲线 3

WTO 3

信息技术 3

农业科学 3

工程科技 3

核能 3

环境 3

展开 ︾

检索范围：

排序： 展示方式：

Modern developments related to nanotechnology and nanoengineering of concrete

Konstantin SOBOLEV

《结构与土木工程前沿（英文）》 2016年 第10卷 第2期   页码 131-141 doi: 10.1007/s11709-016-0343-0

摘要： This paper reports on modern developments related to nanotechnology of cement and concrete. Recent advances in instrumentation and design of advanced nano-composite materials is discussed. New technological directions and historical milestones in nanoengineering and nanomodi?cation of cement-based materials are presented. It is concluded that there is a strong potential of nanotechnology to improve the performance of cement-based materials.

关键词： nanotechnology     cement     concrete     nanoparticle     nano-composite     nanomodification     carbon nanotubes     C-S-H gel     photocatalyst    

HTML PDF 收藏

Quantification of hydration products in cementitious materials incorporating silica nanoparticles

GOEL,S. K. BHATTACHARYYA,G. MISHRA

《结构与土木工程前沿（英文）》 2016年 第10卷 第2期   页码 162-167 doi: 10.1007/s11709-015-0315-9

摘要： In the present work, silica nanoparticles (30-70nm) were supplemented into cement paste to study their influence on degree of hydration, porosity and formation of different type of calcium-silicate-hydrate (C-S-H) gel. As the hydration time proceeds, the degree of hydration reach to 76% in nano-modified cement paste whereas plain cement achieve up to 63% at 28 days. An influence of degree of hydration on the porosity was also determined. In plain cement paste, the capillary porosity at 1hr is ~48%, whereas in silica nanoparticles added cement is ~35 % only, it revealed that silica nanoparticles refines the pore structure due to accelerated hydration mechanism leading to denser microstructure. Similarly, increasing gel porosity reveals the formation of more C-S-H gel. Furthermore, C-S-H gel of different Ca/Si ratio in hydrated cement paste was quantified using X-ray diffractometer and thermogravimetry. The results show that in presence of silica nanoparticles, ~24% C-S-H (Ca/Si<1.0) forms, leading to the formation of polymerised and compact C-S-H. In case of plain cement this type of C-S-H was completely absent at 28 days. These studies reveal that the hydration mechanism of the cement can be tuned with the incorporation of silica nanoparticles and thus, producing more durable cementitious materials.

关键词： degree of hydration     porosity     calcium-silicate-hydrate (C-S-H)     silica nanoparticles    

HTML PDF 收藏

Microstructural and photocatalytic characterization of cement-paste sol-gel synthesized titanium dioxide

Elena CERRO-PRADA,Miguel MANSO,Vicente TORRES,Jesús SORIANO

《结构与土木工程前沿（英文）》 2016年 第10卷 第2期   页码 189-197 doi: 10.1007/s11709-015-0326-6

摘要： A route for the in paste synthesis of TiO loaded cement is described. TiO sols are blended with fresh cement paste as an alternative process to add photocatalytic functionality to cement. The modification of cement paste structure after the addition of TiO sols is analyzed by XRD, SEM and TGA. As a particular microstructural feature, TiO containing calcium silicate hydrate (C-H-S) particles are identified as networking centers of a C-S-H gel fiber matrix. The increase of the TiO sol concentration induces a decrease of pore size and an increase in the specific surface area in the cement composites. The photocatalytic activity of the TiO /cement system is evaluated from the degradation of Methylene Blue (MB) under UV irradiation, monitored through the absorbance at 665 nm. The results show that, although TiO phases reveal no long range order structure, the cement paste exothermal treatment in presence of hydrate products and alkaline conditions leads to a photocatalytic composite. Such new cement matrix may be twofold advantageous since it additionally promotes the formation of C-S-H gel, main determinant of cement mechanical properties.

关键词： cement composites     photocatalytic TiO2     sol-gel     C-S-H gel     microstructure    

HTML PDF 收藏

Effect of a commercial dispersion of multi walled carbon nanotubes on the hydration of an oil well cementing paste

Ocar Aurelio MENDOZA REALES,William C.PEARL Jr,Maria D. M. PAIVA,CristianeR.

《结构与土木工程前沿（英文）》 2016年 第10卷 第2期   页码 174-179 doi: 10.1007/s11709-015-0324-8

摘要： This work studies the influence of a commercial dispersion of multi wall carbon nanotubes (MWCNT) on the hydration of a class G cement paste, at room and elevated down-hole temperatures. The MWCNT dispersion was produced with a solids concentration of 3.0 % by mass and an anionic surfactant as dispersing agent. Cement pastes with water-to-cement ratio of 0.45 and additions of solid MWCNT by mass of cement up to 0.50 % were studied. Isothermal calorimetry results showed a clear retardation of the hydration of cement caused by the surfactant contained in the MWCNT dispersion. Nevertheless, thermogravimetric evaluations showed that once the hydration reaction resumed, the retardation effect of the surfactant did not have a negative impact on the amount of hydration products precipitated. It was concluded that the commercial MWCNT dispersion presents a good potential to be applied in oil well cement pastes.

关键词： carbon nanotubes     surfactant     retardation     combined water     C-S-H    

HTML PDF 收藏

Uncertainty propagation analysis by an extended sparse grid technique

JIA, C. JIANG, C. M. FU, B. Y. NI, C. S. WANG, M. H. PING

《机械工程前沿（英文）》 2019年 第14卷 第1期   页码 33-46 doi: 10.1007/s11465-018-0514-x

摘要： In this paper, an uncertainty propagation analysis method is developed based on an extended sparse grid technique and maximum entropy principle, aiming at improving the solving accuracy of the high-order moments and hence the fitting accuracy of the probability density function (PDF) of the system response. The proposed method incorporates the extended Gauss integration into the uncertainty propagation analysis. Moreover, assisted by the Rosenblatt transformation, the various types of extended integration points are transformed into the extended Gauss-Hermite integration points, which makes the method suitable for any type of continuous distribution. Subsequently, within the sparse grid numerical integration framework, the statistical moments of the system response are obtained based on the transformed points. Furthermore, based on the maximum entropy principle, the obtained first four-order statistical moments are used to fit the PDF of the system response. Finally, three numerical examples are investigated to demonstrate the effectiveness of the proposed method, which includes two mathematical problems with explicit expressions and an engineering application with a black-box model.

关键词： uncertainty propagation analysis     extended sparse grid     maximum entropy principle     extended Gauss integration     Rosenblatt transformation     high-order moments analysis    

HTML PDF 收藏

A Bayesian modeling approach to bi-directional pedestrian flows in carnival events

S. Q. XIE, S. C. WONG, William H. K. LAM

《工程管理前沿（英文）》 2017年 第4卷 第4期   页码 483-489 doi: 10.15302/J-FEM-2017023

摘要： Bi-directional pedestrian flows are common at crosswalks, footpaths, and shopping areas. However, the properties of pedestrian movement may vary in urban areas according to the type of walking facility. In recent years, crowd movements at carnival events have attracted the attention of researchers. In contrast to pedestrian behavior in other walking facilities, pedestrians whose attention is attracted by carnival displays or activities may slow down and even stop walking. The Lunar New Year Market is a traditional carnival event in Hong Kong held annually one week before the Lunar New Year. During the said event, crowd movements can be easily identified, particularly in Victoria Park, where the largest Lunar New Year Market in Hong Kong is hosted. In this study, we conducted a video-based observational survey to collect pedestrian flow and speed data at the Victoria Park Lunar New Year Market on the eve of the Lunar New Year. Using the collected data, an extant mathematical model was calibrated to capture the relationships between the relevant macroscopic quantities, thereby providing insight into pedestrian behavior at the carnival event. Bayesian inference was employed to calibrate the model by using prior data obtained from a previous controlled experiment. Results obtained enhance our understanding of crowd behavior under different conditions at carnival events, thus facilitating the improvement of the safety and efficiency of similar events in the future.

关键词： pedestrian flow model     bi-directional interactions     empirical studies     Bayesian inference    

HTML PDF 收藏

Full-band error control and crack-free surface fabrication techniques for ultra-precision fly cutting of large-aperture KDP crystals

H. ZHANG, S. F. WANG, C. H. AN, J. WANG, Q. XU

《机械工程前沿（英文）》 2017年 第12卷 第2期   页码 193-202 doi: 10.1007/s11465-017-0448-8

摘要：

Large-aperture potassium dihydrogen phosphate (KDP) crystals are widely used in the laser path of inertial confinement fusion (ICF) systems. The most common method of manufacturing half-meter KDP crystals is ultra-precision fly cutting. When processing KDP crystals by ultra-precision fly cutting, the dynamic characteristics of the fly cutting machine and fluctuations in the fly cutting environment are translated into surface errors at different spatial frequency bands. These machining errors should be suppressed effectively to guarantee that KDP crystals meet the full-band machining accuracy specified in the evaluation index. In this study, the anisotropic machinability of KDP crystals and the causes of typical surface errors in ultra-precision fly cutting of the material are investigated. The structures of the fly cutting machine and existing processing parameters are optimized to improve the machined surface quality. The findings are theoretically and practically important in the development of high-energy laser systems in China.

关键词： ultra-precision fly cutting     large-aperture KDP crystals     spatial frequency     processing error    

HTML PDF 收藏

A density functional theory study of methane activation on MgO supported NiM cluster: role of M on C–H

《化学科学与工程前沿（英文）》 2022年 第16卷 第10期   页码 1485-1492 doi: 10.1007/s11705-022-2169-8

摘要： Methane activation is a pivotal step in the application of natural gas converting into high-value added chemicals via methane steam/dry reforming reactions. Ni element was found to be the most widely used catalyst. In present work, methane activation on MgO supported Ni–M (M = Fe, Co, Cu, Pd, Pt) cluster was explored through detailed density functional theory calculations, compared to pure Ni cluster. CH4 adsorption on Cu promoted Ni cluster requires overcoming an energy of 0.07 eV, indicating that it is slightly endothermic and unfavored to occur, while the adsorption energies of other promoters M (M = Fe, Co, Pd and Pt) are all higher than that of pure Ni cluster. The role of M on the first C–H bond cleavage of CH4 was investigated. Doping elements of the same period in Ni cluster, such as Fe, Co and Cu, for C–H bond activation follows the trend of the decrease of metal atom radius. As a result, Ni–Fe shows the best ability for C–H bond cleavage. In addition, doping the elements of the same family, like Pd and Pt, for CH4 activation is according to the increase of metal atom radius. Consequently, C–H bond activation demands a lower energy barrier on Ni–Pt cluster. To illustrate the adsorptive dissociation behaviors of CH4 at different Ni–M clusters, the Mulliken atomic charge was analyzed. In general, the electron gain of CH4 binding at different Ni–M clusters follows the sequence of Ni–Cu (–0.02 e) < Ni (–0.04 e) < Ni–Pd (–0.08 e) < Ni–Pt (–0.09 e) < Ni–Co (–0.10 e) < Ni–Fe (–0.12 e), and the binding strength between catalysts and CH 4 raises with the CH4 electron gain increasing. This work provides insights into understanding the role of promoter metal M on thermal-catalytic activation of CH4 over Ni/MgO catalysts, and is useful to interpret the reaction at an atomic scale.

关键词： CH4 dissociation     Ni–M     C–H bond activation     charge transfer    

HTML PDF 收藏

施工现场安全危险源实时监控与安全风险预测方法研究

LAM,李启明,Michael C. H. YAM,David A. S. CHEW

《中国工程科学》 2010年 第12卷 第3期   页码 68-72

摘要：

对国内外建筑业施工现场安全风险的研究进行了文献综述，针对目前研究的不足之处，提出了施工现场安全危险源实时监控和安全风险实时预测的示意性模型，并详细解释了该模型的含义和方法。研究将提供一种基于前馈信号的施工现场安全危险源实时监控和安全风险实时预测的方法；并通过将现有研究的视角引入到施工现场关键安全危险源的前馈信号上，为进一步的研究打下良好的理论基础。

关键词： 施工现场     安全风险     实时预测     前馈信号     信号检测理论    

HTML PDF 收藏

基于S3C2410的GPRS数据终端的设计

孙学用

《中国工程科学》 2007年 第9卷 第12期   页码 94-96

摘要： 提出了以S3C2410处理器为核心，以SIM100-E为GPRS通信模块,构建了一套嵌入式Internet数据终端的方案，对其硬件构成及工作流程进行了讨论，描述了其软件层次结构，并详细讲解了基于该平台的

关键词： GPRS；嵌入式Internet；S3C2410；SIM100-E    

HTML PDF 收藏

基于中国族群的个性化增材制造全膝关节置换假体设计 Article

徐振星, 梁国穗, 秦江辉, 石杜芳, P. Augut, 黄文扬, 周冠豪, 黄雪莹, 陈致远, 赖毓霄, 容树恒, 秦岭, 张颖恺

《工程（英文）》 2021年 第7卷 第3期   页码 386-394 doi: 10.1016/j.eng.2020.02.017

摘要：

目前市场上大多数全膝关节置换（TKR）假体是根据高加索人的体型设计的。大量研究表明，不同种族之间的人体解剖结构不同，中国的TKR患者与现有进口假体并不匹配。本研究测量了52名中国男性和女性的膝关节计算机断层扫描（CT）图像。通过定义参数和几何尺寸，进行相关性分析。从测量结果中识别出关键参数。测量膝关节详细几何形状的坐标数据。基于与所标识的关键参数相关的解剖坐标系统，生成了可变形的三维（3D）膝关节模型。然后根据分析结果设计假体，进行表面匹配分析、切骨分析和尸体试验，并将其与商业假体产品进行比较以验证我们的设计。本研究设计的股骨组件与两种商业器械相比，具有更高的准确性[均方根比（RMS PS）为（1.08 ± 0.20） mm]，而切除的骨量最低（27 412 mm3）。这项研究为基于族群的患者特定的股骨假体设计提出了一种新方法。使用一个易于获取的尺寸[即上髁宽度（ECW）]作为输入，可以根据分析的测量数据设计特定患者的股骨假体，并通过增材制造（AM）方法进行制造。同时，在原始CT扫描数据中将重建的股骨表面与原股骨表面进行比较。在所有数据中，重建的股骨表面的平均RMS PS距离为（1.10 ± 0.18）mm，这与使用多个X射线照片作为输入数据的其他统计形状建模方法相当。目前市场上对基于中国族群人体测量的膝关节假体有很大需求。本研究基于中国族群人体测量学，设计出更适合中国患者的膝关节假体，并保留了更多的骨量，这是迈向个性化膝关节假体增材制造的重要一步。

关键词： 增材制造     基于族群的设计     全膝关节置换     膝关节假体     人体测量    

HTML PDF 收藏

Analysis of the double-layer α-Si:H emitter with different doping concentrations for α-Si:H/c-Si heterojunction

Haibin HUANG,Gangyu TIAN,Tao WANG,Chao GAO,Jiren YUAN,Zhihao YUE,Lang ZHOU

《能源前沿（英文）》 2017年 第11卷 第1期   页码 92-95 doi: 10.1007/s11708-016-0432-8

摘要： Double-layer emitters with different doping concentrations (DLE) have been designed and prepared for amorphous silicon/crystalline silicon (α-Si:H/c-Si) heterojunction solar cells. Compared with the traditional single layer emitter, both the experiment and the simulation (AFORS-HET, http://www.paper.edu.cn/html/releasepaper/2014/04/282/) prove that the double-layer emitter increases the short circuit current of the cells significantly. Based on the quantum efficiency (QE) results and the current-voltage-temperature analysis, the mechanism for the experimental results above has been investigated. The possible reasons for the increased current include the enhancement of the QE in the short wavelength range, the increase of the tunneling probability of the current transport and the decrease of the activation energy of the emitter layers.

关键词： double-layer emitter     α-Si:H/c-Si heterojunction solar cell     short circuit current     quantum efficiency     current-voltage-temperature    

HTML PDF 收藏

Photoelectrocatalytic generation of H and S from toxic HS by using a novel BiOI/WO nanoflake array photoanode

《能源前沿（英文）》 2021年 第15卷 第3期   页码 744-751 doi: 10.1007/s11708-021-0775-7

摘要： In this paper, a photoelectrocatalytic (PEC) recovery of toxic H2S into H2 and S system was proposed using a novel bismuth oxyiodide (BiOI)/ tungsten trioxide (WO3) nano-flake arrays (NFA) photoanode. The BiOI/WO3 NFA with a vertically aligned nanostructure were uniformly prepared on the conductive substrate via transformation of tungstate following an impregnating hydroxylation of BiI3. Compared to pure WO3 NFA, the BiOI/WO3 NFA promotes a significant increase of photocurrent by 200%. Owing to the excellent stability and photoactivity of the BiOI/WO3 NFA photoanode and I–/I 3− catalytic system, the PEC system toward splitting of H2S totally converted S2– into S without any polysulfide ( Sx n−) under solar-light irradiation. Moreover, H2 was simultaneously generated at a rate of about 0.867 mL/(h·cm). The proposed PEC H2S splitting system provides an efficient and sustainable route to recover H2 and S.

关键词： bismuth oxyiodide (BiOI)/ tungsten trioxide (WO3) nano-flake arrays (NFA)     photoelectrocatalytic (PEC)     H2S splitting     H2     S    

HTML PDF 收藏

Modeling of alkali-silica reaction in concrete: a review

WANG, Q.C. SUN, C.H. ZHANG, D.R.J. OWEN

《结构与土木工程前沿（英文）》 2012年 第6卷 第1期   页码 1-18 doi: 10.1007/s11709-012-0141-2

摘要： This paper presents a comprehensive review of modeling of alkali-silica reaction (ASR) in concrete. Such modeling is essential for investigating the chemical expansion mechanism and the subsequent influence on the mechanical aspects of the material. The concept of ASR and the mechanism of expansion are first outlined, and the state-of-the-art of modeling for ASR, the focus of the paper, is then presented in detail. The modeling includes theoretical approaches, meso- and macroscopic models for ASR analysis. The theoretical approaches dealt with the chemical reaction mechanism and were used for predicting pessimum size of aggregate. Mesoscopic models have attempted to explain the mechanism of mechanical deterioration of ASR-affected concrete at material scale. The macroscopic models, chemo-mechanical coupling models, have been generally developed by combining the chemical reaction kinetics with linear or nonlinear mechanical constitutive, and were applied to reproduce and predict the long-term behavior of structures suffering from ASR. Finally, a conclusion and discussion of the modeling are given.

关键词： alkali-silica reaction (ASR)     modeling     concrete     mesoscopic     macroscopic    

HTML PDF 收藏

Development progress of China’s 600 km/h high-speed magnetic levitation train

《工程管理前沿（英文）》 2022年 第9卷 第3期   页码 509-515 doi: 10.1007/s42524-022-0199-z

摘要： . {{custom_ra.content}} . . . {{article.highlightEn}} . . . {{article.abstractEn}} . . . {{article.authorSummayEn}} . . . . .

关键词： 600 km/h high-speed magnetic levitation train     development history     technological innovation    

HTML PDF 收藏

标题 作者 时间 类型 操作

Modern developments related to nanotechnology and nanoengineering of concrete

Konstantin SOBOLEV

期刊论文

Quantification of hydration products in cementitious materials incorporating silica nanoparticles

GOEL,S. K. BHATTACHARYYA,G. MISHRA

期刊论文

Microstructural and photocatalytic characterization of cement-paste sol-gel synthesized titanium dioxide

Elena CERRO-PRADA,Miguel MANSO,Vicente TORRES,Jesús SORIANO

期刊论文

Effect of a commercial dispersion of multi walled carbon nanotubes on the hydration of an oil well cementing paste

Ocar Aurelio MENDOZA REALES,William C.PEARL Jr,Maria D. M. PAIVA,CristianeR.

期刊论文

Uncertainty propagation analysis by an extended sparse grid technique

JIA, C. JIANG, C. M. FU, B. Y. NI, C. S. WANG, M. H. PING

期刊论文

A Bayesian modeling approach to bi-directional pedestrian flows in carnival events

S. Q. XIE, S. C. WONG, William H. K. LAM

期刊论文

Full-band error control and crack-free surface fabrication techniques for ultra-precision fly cutting of large-aperture KDP crystals

H. ZHANG, S. F. WANG, C. H. AN, J. WANG, Q. XU

期刊论文

A density functional theory study of methane activation on MgO supported NiM cluster: role of M on C–H

期刊论文

施工现场安全危险源实时监控与安全风险预测方法研究

LAM,李启明,Michael C. H. YAM,David A. S. CHEW

期刊论文

基于S3C2410的GPRS数据终端的设计

孙学用

期刊论文

基于中国族群的个性化增材制造全膝关节置换假体设计

徐振星, 梁国穗, 秦江辉, 石杜芳, P. Augut, 黄文扬, 周冠豪, 黄雪莹, 陈致远, 赖毓霄, 容树恒, 秦岭, 张颖恺

期刊论文

Analysis of the double-layer α-Si:H emitter with different doping concentrations for α-Si:H/c-Si heterojunction

Haibin HUANG,Gangyu TIAN,Tao WANG,Chao GAO,Jiren YUAN,Zhihao YUE,Lang ZHOU

期刊论文

Photoelectrocatalytic generation of H and S from toxic HS by using a novel BiOI/WO nanoflake array photoanode

期刊论文

Modeling of alkali-silica reaction in concrete: a review

WANG, Q.C. SUN, C.H. ZHANG, D.R.J. OWEN

期刊论文

Development progress of China’s 600 km/h high-speed magnetic levitation train

期刊论文