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Long-term behavior and safety assessment of Sance Rockfill Dam

Marta DOLEZALOVA, Ivo HLADIK

《结构与土木工程前沿（英文）》 2011年 第5卷 第1期   页码 79-89 doi: 10.1007/s11709-010-0010-9

摘要： Safety assessment of the 62 m high Sance Rockfill Dam based on long-term monitoring results and their simulation by numerical models is presented in the paper. Unexpectedly large settlements and horizontal movements of the crest together with the steep downstream slope questioned the safety of the dam. Calibrated 2D and 3D models fitting the monitoring results were applied for the safety assessment of the dam including slope stability analysis and estimation of the clay core cracking and hydraulic fracturing hazard. The modeling results contributed to the rehabilitation concept and project of the dam.

关键词： rockfill dam     path dependence     creep     calibration     cracking     hydraulic fracturing hazard    

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Experimental research on the creep behavior and bearing capacity of repeatedly prestressed concrete beam

SHAO Xudong, LI Lifeng, YANG Jianjun

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 305-311 doi: 10.1007/s11709-007-0040-0

摘要： In the prestress tensioning process of medium or short span prestressed concrete beam bridges, there are always many serious problems, such as the camber of straight beam being too large, curved beam going crosswise, and columns of rigid beam bridge cracking, that can be commonly seen because of its greater additional stress in prestressing. To solve the above problems, a new concept of repeatedly prestressed bridge structure was innovatively proposed in this work. It was proved, through theoretical and experimental comparison between this new structure and the traditional prestressed structure, that the application of repeated prestressing technology can greatly improve the mechanical and deformational performance of the low height beam during construction and long-term use. Furthermore, a kind of computational formula to calculate creep strain and deformation due to repeated prestressing in terms of time was derived in this paper and the bearing capacity of this new structure has been tested. Finally, the work concludes that there is a bright application prospect for this new structure for medium and short span prestressed beam bridges to control deformations.

关键词： computational     cracking     technology     prestressed concrete     application prospect    

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Assessment of fracture process in forta and polypropylene fiber-reinforced concrete using experimental analysis and digital image correlation

Seyed Hamid KALALI; Hamid ESKANDARI-NADDAF; Seyed Ali EMAMIAN

《结构与土木工程前沿（英文）》 2022年 第16卷 第12期   页码 1633-1652 doi: 10.1007/s11709-022-0876-3

摘要： This paper aims to characterize the evolution of the fracture process and the cracking behavior in Forta-Ferro (FF) and Polypropylene (PP) fiber-reinforced concrete under the uniaxial compressive loading using experimental analysis and digital image correlation (DIC) on the surface displacement. For this purpose, 6 mix designs, including two FF volume fractions of 0.10, and 0.20% and three PP volume fractions of 0.20, 0.30, and 0.40%, in addition to a control mix were evaluated according to compressive strength, modulus of elasticity, toughness index, and stress-strain curves. The influence of fibers on the microstructural texture of specimens was analyzed by scanning electron microscope (SEM) imaging. Results show that FF fiber-reinforced concrete specimens demonstrated increased ductility and strength compared to PP fiber. DIC results revealed that the major crack and fracture appeared at the peak load of the control specimen due to brittleness and sudden gain of large lateral strain, while a gradual increase in micro-crack quantity at 75% of peak load was observed in the fiber specimens, which thenbegan to connect with each other up to the final fracture. The accuracy of the results supports DIC as a reliable alternative for the characterization of the fracture process in fiber-reinforced concrete.

关键词： fiber-reinforced concrete     forta-ferro and polypropylene fiber     fracture process     cracking behavior     digital image correlation    

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Effects of microfine aggregate in manufactured sand on bleeding and plastic shrinkage cracking of concrete

Branavan ARULMOLY; Chaminda KONTHESINGHA; Anura NANAYAKKARA

《结构与土木工程前沿（英文）》 2022年 第16卷 第11期   页码 1453-1473 doi: 10.1007/s11709-022-0877-2

摘要： Construction industries have started to utilize manufactured sand (MS) as an effective alternative for river sand in concrete. High-grade parent rocks are crushed to obtain MS, which also produces a considerable amount of microfine aggregate (MFA). The higher percentage of MFA could lead to both positive and negative effects on the performance of cement-based mixes. This research was done to examine the influence of varying MFA levels, specifically 0%, 3%, 6%, 9%, and 12% (by weight) as the partial replacements of MS on bleeding and plastic shrinkage cracking of concrete. In addition to the varying MFA levels, some concrete mixes also included fly ash (FA) and superplasticizer to investigate the effect of free-water content in the mixes. The bleeding test data were taken as on-site measurements, while the cracks from the plastic shrinkage cracking test were evaluated using an image processing technique. The results concluded that the MFA replacements and the effective water-to-cement ratio have a significant effect on the selected concrete properties. With the increasing replacement levels, cumulative bleeding and crack initiation life gradually decreased, while a progressive increase was observed for crack width, crack length, and crack area.

关键词： manufactured sand     fresh concrete     microfines     admixtures     shrinkage     cracking    

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FUNCTIONAL GAIN OF FRUIT NETTED-CRACKING IN AN INTROGRESSION LINE OF TOMATO WITH HIGHER EXPRESSION OF

《农业科学与工程前沿（英文）》 2021年 第8卷 第2期

摘要：

Fruit cracking is a major disorder that affects the integrity of fruit and reduces the commercial value of tomato and other fleshy fruit. Here, we have found a novel fruit ‘netted-cracking’ (FNC) phenotype in tomato introgression line IL4-4 which is present in neither the donor parent (LA0716) nor the receptor parent (M82). An F2 population was generated by crossing IL4-4 with M82 to genetically characterize the FNC gene and this showed that a single dominant gene determined fruit netted-cracking. Further map-based cloning narrowed down the FNC locus to a 230 kb region on chromosome 4. Sequencing and annotation analysis show that FNC(Solyc04 g082540) was the most likely candidate gene. Functional characterization of FNC by overexpressing FNCAC and FNCIL4-4resulted in the fruit netted-cracking phenotype, suggesting that the FNC transcript level results in the functional gain of fruit netted-cracking. These findings were further confirmed by FNC ortholog in netted-cracking pepper and melon, indicating a common regulatory mechanism in different plant species. Furthermore, cytoplasm and nucleus-localized FNC indicates increased expression of genes involved in suberin, lignin, lipid transport and cell wall metabolism. These findings provide novel genetic insights into fruit netted-cracking and offer a way to promote molecular improvement toward cracking resistant cultivars.

 

关键词： fine mapping / fruit netted-cracking / introgression line / transcript level    

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Theoretical study on the confine-stiffening effect and fractal cracking of square concrete filled steel

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1317-1336 doi: 10.1007/s11709-021-0763-3

摘要： Tension stress in steel-concrete composite is widely observed in engineering design. Based on an experimental program on tension performance of three square concrete-filled tubes (SCFT), the tension theory of SCFT is proposed using a mechanics-based approach. The tension stiffening effect, the confining strengthening effect and the confining stiffening effect, observed in tests of SCFTs are included in the developed tension theory model. Subsequently, simplified constitutive models of steel and concrete are proposed for the axial tension performance of SCFT. Based on the MSC.MARC software, a special fiber beam-column element is proposed to include the confining effect of SCFTs under tension and verified. The proposed analytical theory, effective formulas, and equivalent constitutive laws are extensively verified against three available tests reported in the literature on both global level (e.g., load-displacement curves) and strain level. The experimental verification proves the accuracy of the proposed theory and formulations in simulating the performance of SCFT members under tension with the capability to accurately predict the tensile strength and stiffness enhancements and realistically simulate the fractal cracking phenomenon.

关键词： square concrete filled tubes     confine-stiffening     confine-strengthening     fractal cracking     fracture    

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Hierarchical approach for fatigue cracking performance evaluation in asphalt pavements

Ibrahim ONIFADE, Yared DINEGDAE, Björn BIRGISSON

《结构与土木工程前沿（英文）》 2017年 第11卷 第3期   页码 257-269 doi: 10.1007/s11709-017-0410-1

摘要： In this paper, a hierarchical approach is proposed for the evaluation of fatigue cracking in asphalt concrete pavements considering three different levels of complexities in the representation of the material behaviour, design parameters characterization and the determination of the pavement response as well as damage computation. Based on the developed hierarchical approach, three damage computation levels are identified and proposed. The levels of fatigue damage analysis provides pavement engineers a variety of tools that can be used for pavement analysis depending on the availability of data, required level of prediction accuracy and computational power at their disposal. The hierarchical approach also provides a systematic approach for the understanding of the fundamental mechanisms of pavement deterioration, the elimination of the empiricism associated with pavement design today and the transition towards the use of sound principles of mechanics in pavement analysis and design.

关键词： fatigue cracking     energy based     crack initiation     mechanistic approach     pavement analysis    

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Influence of surface cracking, anchor head profile, and anchor head size on cast-in headed anchors in

《结构与土木工程前沿（英文）》   页码 1163-1187 doi: 10.1007/s11709-023-0987-5

摘要： In this study, the concrete cone capacity, concrete cone angle, and load–displacement response of cast-in headed anchors in geopolymer concrete are explored using numerical analyses. The concrete damaged plasticity (CDP) model in ABAQUS is used to simulate the behavior of concrete substrates. The tensile behavior of anchors in geopolymer concrete is compared with that in normal concrete as well as that predicted by the linear fracture mechanics (LFM) and concrete capacity design (CCD) models. The results show that the capacity of the anchors in geopolymer concrete is 30%–40% lower than that in normal concrete. The results also indicate that the CCD model overestimates the capacity of the anchors in geopolymer concrete, whereas the LFM model provides a much more conservative prediction. The extent of the difference between the predictions by the numerical analysis and those of the above prediction models depends on the effective embedment depth of the anchor and the anchor head size. The influence of concrete surface cracking on the capacity of the anchor is shown to depend on the location of the crack and the effective embedment depth. The influence of the anchor head profile on the tensile capacity of the anchors is found to be insignificant.

关键词： cast-in anchor     concrete cone capacity     geopolymer concrete     head size     surface crack     anchor profile    

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催化裂解架起了炼油与化工之间的桥梁

李再婷

《中国工程科学》 1999年 第1卷 第2期   页码 67-71

摘要：

催化裂解是以石油中的重油为原料，用催化方法生产丙烯等基本有机化工原料的技术。在世界上我国首先研究开发了此新工艺及催化剂，并于1990年成功进行了工业示范。迄今，国内外已有七套应用该技术的工业装置建成并投产。生产的丙烯等化工原料已分别用来合成了高质量的聚丙烯、聚乙烯及丙烯腈等化学品。目前催化裂解已可应用更重质的原料，如常压渣油，并开发出能适合不同原料的多种催化剂。文中重点介绍了应用该技术在泰国建成的一套催化裂解装置的生产情况。

关键词： 催化裂解     石油化学工业     丙烯     异丁烯    

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A novel fluid catalytic cracking process for maximizing

Youhao Xu, Shouye Cui

《化学科学与工程前沿（英文）》 2018年 第12卷 第1期   页码 9-23 doi: 10.1007/s11705-017-1696-1

摘要： The maximizing iso-paraffins (MIP) developed by RIPP has improved gasoline quality to meet the demand of motor gasoline specification. A concept that two different reaction zones include cracking zone and conversion zone is proposed as the fundamental of MIP by research on fluid catalytic cracking (FCC) reaction chemistry. Based on the concept, the MIP process is featured by applying a novel sequential two-zone riser in conjunction with proprietary catalyst and engineering technique. The developed MIP process can not only improve gasoline yield or gasoline plus propylene yields but also produce gasoline with a higher content of -paraffins and a lower content of sulfur. A minimum octane number loss is achieved when MIP gasoline is treated by downstream desulfurization technology (RSDS/S Zorb). The combination of MIP and RSDS/S Zorb processes creates a very competitive route, which is different from the technical route used by other developed countries, to upgrade the quality of motor gasoline with the lowest economic costs in China. In just one decade, the processing capacity of MIP units has accounted for about 60% of the domestic total processing capacity of FCC units. The MIP process is gradually becoming a new generation of FCC technology.

关键词： gasoline     iso-paraffins     FCC     desulfurization     octane number    

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靶向生产低碳烯烃的催化裂化技术——反应机理、生产方案和工艺展望 Review

许友好, Yanfen Zuo, Wenjie Yang, Xingtian Shu, Wei Chen, Anmin Zheng

《工程（英文）》 2023年 第30卷 第11期   页码 100-109 doi: 10.1016/j.eng.2023.02.018

摘要：

Light olefins are important organic building blocks in the chemicals industry. The main low-carbon olefin production methods, such as catalytic cracking and steam cracking, have considerable room for improvement in their utilization of hydrocarbons. This article provides a thorough overview of recent studies on catalytic cracking, steam cracking, and the conversion of crude oil processes. To maximize the production of light olefins and reduce carbon emissions, the perceived benefits of various technologies are examined. Taking olefin generation and conversion as a link to expand upstream and downstream processes, a targeted catalytic cracking to olefins (TCO) process is proposed to meet current demands for the transformation of oil refining into chemical production. The main innovations of this process include a multiple feedstock supply, the development of medium-sized catalysts, and a diameter-transformed fluidized-bed reactor with different feeding schemes. In combination with other chemical processes, TCO is expected to play a critical role in enabling petroleum refining and chemical processes to achieve low carbon dioxide emissions.

关键词： Light olefins     Steam cracking     Catalytic cracking     TCO process     Oil processing revolution    

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Study on reformulation of fluid catalytic cracking gasoline and increasing production of light olefins

YAN Pingxiang, MENG Xianghai, GAO Jinsen, XU Chunming, SUI Zhiyu

《化学科学与工程前沿（英文）》 2008年 第2卷 第1期   页码 74-79 doi: 10.1007/s11705-008-0016-1

摘要： The effects of reaction temperature, mass ratio of catalyst to oil, space velocity, and mass ratio of water to oil on the product distribution, the yields of light olefins (light olefins including ethylene, propylene and butylene) and the composition of the fluid catalytic cracking (FCC) gasoline upgraded over the self-made catalyst GL in a confined fluidized bed reactor were investigated. The experimental results showed that FCC gasoline was obviously reformulated under appropriate reaction conditions. The olefins (olefins with C atom number above 4) content of FCC gasoline was markedly reduced, and the aromatics content and octane number were increased. The upgraded gasoline met the new standard of gasoline, and meanwhile, higher yields of light olefins were obtained. Furthermore, higher reaction temperature, higher mass ratio of catalyst to oil, higher mass ratio of water to oil, and lower space velocity were found to be beneficial to FCC gasoline reformulation and light olefins production.
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Formation of coke in thermal cracking of jet fuel under supercritical conditions

ZHU Yuhong, YU Caixiang, LI Zimu, MI Zhentao, ZHANG Xiangwen

《化学科学与工程前沿（英文）》 2008年 第2卷 第1期   页码 17-21 doi: 10.1007/s11705-008-0024-1

摘要： Continuous-flow reactor experiments were carried out to study coke formation from thermal cracking of home-made jet fuel RP-3 under supercritical conditions. The mechanism and precursor of coke forming were analyzed. The starting cracking temperature of RP-3 fuel was determined to be 471.8°C by differential scanning calorimetry (DSC). Temperature-programmed oxidation and scanning electron microscopy (SEM) characterizations of the stressed tubes showed that there are three different coke species including chemisorbed carbon, amorphous carbon and filamentous coke in the solid deposits. More than 90% of coke deposits are carried away by the supercritical fluid, which has strong capabilities of extraction for coke deposits and their precursors. There were 17.1 wt-% of iron and 11.1 wt-% of chromium found on the coke surface detected by energy dispersive spectroscopy (EDS) which suggests carburetion on alloy. RP-3 fuel and its cracking liquids were analyzed by GC-MS,which showed that the content of alkyl benzene and alkyl naphthalene increased evidently in cracking liquids.

关键词： dispersive spectroscopy     different     extraction     calorimetry     filamentous    

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Thermal cracking of waste printed wiring boards for mechanical recycling by using residual steam preprocessing

Yao CHEN, Jinhui LI, Huabo DUAN, Zhishi WANG

《环境科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 167-174 doi: 10.1007/s11783-011-0308-4

摘要： Mechanical waste-processing methods, which combine crushing and separation processes for the recovery of valuable materials, have been widely applied in waste printed wiring board (PWB) treatment. However, both the high impact toughness and the tensile and flexural strengths of whole PWB with a laminated structure result in great energy consumption and severe abrasion of the cutters during multi-level crushing. In addition, the high temperatures occurring in continual crushing probably cause the decomposition of the polymer matrix. A thermal-crack method using residual steam as the heating medium has been developed to pre-treat waste PWBs. This treatment reduces the mechanical strength in order to improve the recovery rate of valuable materials in subsequent mechanical recycling. The changes of the PWBs’ macro-mechanical properties were studied to evaluate thermal expansion impacts associated with changes in temperature, and the dynamic dislocation micro-structures were observed to identify the fracture mechanism. The results showed that thermal cracking with steam at the temperature of 500 K can effectively attenuate the mechanical properties of waste PWBs, by reducing the impact, tensile and flexural strengths respectively, by 59.2%, 49.3% and 51.4%, compared to untreated PWB. Thermal expansion can also facilitate the separation of copper from glass fiber by reducing peel resistance by 95.4% at 500 K. It was revealed that the flexural fracture was a transverse cracking caused by concentrated stress when the heating temperature was less than 500 K, and shifted to a vertical cracking after exceeding 500 K.

关键词： waste printed wiring board (PWB)     residue steam     thermal-crack     mechanical properties    

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Catalytic cracking of endothermic fuels in coated tube reactor

LI Jia, ZOU Jijun, ZHANG Xiangwen, GUO Wei, MI Zhentao

《化学科学与工程前沿（英文）》 2008年 第2卷 第2期   页码 181-185 doi: 10.1007/s11705-008-0032-1

摘要： Suspensoid of HZSM-5 or HY zeolites mixed with a self-made ceramic-like binder was coated on the inner wall of a tubular reactor by gas-aided fluid displacement technology. The coated zeolites were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The coating thickness is 10–20 ?m and the particle size of the zeolites is in the range of 1–5 ?m. In the coated reactor, cracking of endothermic fuels including -dodecane and aviation fuel RP-3 was carried out separately under supercritical conditions at 600°C and 625°C to investigate their heat sinks and conversion of catalytic reactions. For the reaction catalyzed by HY(25% mass fraction) coating, the heat sink capacity of -dodecane are 815.7 and 901.9 kJ/kg higher than that of the bare tube at 600°C and at 625°C, respectively. Conversion of -dodecane also increases from 42% to 60% at 600°C and from 66% to 80% at 625°C. The coated zeolite can significantly inhibit the carbon deposition during supercritical cracking reactions.

关键词： HZSM-5     self-made ceramic-like     gas-aided     Conversion     Suspensoid    

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标题 作者 时间 类型 操作

Long-term behavior and safety assessment of Sance Rockfill Dam

Marta DOLEZALOVA, Ivo HLADIK

期刊论文

Experimental research on the creep behavior and bearing capacity of repeatedly prestressed concrete beam

SHAO Xudong, LI Lifeng, YANG Jianjun

期刊论文

Assessment of fracture process in forta and polypropylene fiber-reinforced concrete using experimental analysis and digital image correlation

Seyed Hamid KALALI; Hamid ESKANDARI-NADDAF; Seyed Ali EMAMIAN

期刊论文

Effects of microfine aggregate in manufactured sand on bleeding and plastic shrinkage cracking of concrete

Branavan ARULMOLY; Chaminda KONTHESINGHA; Anura NANAYAKKARA

期刊论文

FUNCTIONAL GAIN OF FRUIT NETTED-CRACKING IN AN INTROGRESSION LINE OF TOMATO WITH HIGHER EXPRESSION OF

期刊论文

Theoretical study on the confine-stiffening effect and fractal cracking of square concrete filled steel

期刊论文

Hierarchical approach for fatigue cracking performance evaluation in asphalt pavements

Ibrahim ONIFADE, Yared DINEGDAE, Björn BIRGISSON

期刊论文

Influence of surface cracking, anchor head profile, and anchor head size on cast-in headed anchors in

期刊论文

催化裂解架起了炼油与化工之间的桥梁

李再婷

期刊论文

A novel fluid catalytic cracking process for maximizing

Youhao Xu, Shouye Cui

期刊论文

靶向生产低碳烯烃的催化裂化技术——反应机理、生产方案和工艺展望

许友好, Yanfen Zuo, Wenjie Yang, Xingtian Shu, Wei Chen, Anmin Zheng

期刊论文

Study on reformulation of fluid catalytic cracking gasoline and increasing production of light olefins

YAN Pingxiang, MENG Xianghai, GAO Jinsen, XU Chunming, SUI Zhiyu

期刊论文

Formation of coke in thermal cracking of jet fuel under supercritical conditions

ZHU Yuhong, YU Caixiang, LI Zimu, MI Zhentao, ZHANG Xiangwen

期刊论文

Thermal cracking of waste printed wiring boards for mechanical recycling by using residual steam preprocessing

Yao CHEN, Jinhui LI, Huabo DUAN, Zhishi WANG

期刊论文

Catalytic cracking of endothermic fuels in coated tube reactor

LI Jia, ZOU Jijun, ZHANG Xiangwen, GUO Wei, MI Zhentao

期刊论文