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Correlation between tension softening relation and crack extension resistance in concrete

Xiufang ZHANG , Shilang XU ,

《结构与土木工程前沿（英文）》 2009年第3卷第3期页码 323-329 doi: 10.1007/s11709-009-0041-2

摘要： Changes of the material fracture energy consumption with crack propagation can be described by a crack extension resistance curve, one of the fundamental fracture criteria in crack mechanics. Recently, experimental observation of the fracture behavior in concrete was used to develop a new fracture criterion, the crack extension resistance curve, to analyze crack propagation during the entire concrete fracture process. The variation of the crack extension resistance is mainly associated with the energy consumption in the fracture process zone ahead of the stress-free crack tip. The crack extension resistance is then a function of the softening curve, which is a basic mechanical property in the fracture process zone. The relationship between the softening curve and the crack extension resistance curve is then analyzed based on results of three-point bending beams tests. The results indicate that the characteristic points of the crack extension resistance curve is closely related to the characteristic point on used tension softening curve.

关键词： concrete fracture process zone crack extension G_R resistance tension softening curve

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Preparation and characterization of hydrothermally engineered TiO

Kanchapogu Suresh, G. Pugazhenthi, R. Uppaluri

《化学科学与工程前沿（英文）》 2017年第11卷第2期页码 266-279 doi: 10.1007/s11705-017-1608-4

摘要： This work targets the preparation and characterization of an inexpensive TiO -fly ash composite membrane for oily wastewater treatment. The composite membrane was fabricated by depositing a hydrophilic TiO layer on a fly ash membrane via the hydrothermal method, and its structural, morphological and mechanical properties were evaluated. The separation potential of the composite membrane was evaluated for 100–200 mg·L synthetic oily wastewater solutions. The results show that the composite membrane has excellent separation performance and can provide permeate stream with oil concentration of only 0.26–5.83 mg·L . Compared with the fly ash membrane in the average permeate flux and performance index (49.97 × 10 m ·m ·s and 0.4620%, respectively), the composite membrane exhibits better performance (51.63 × 10 m ·m ·s and 0.4974%). For the composite ash membrane, the response surface methodology based analysis inferred that the optimum process parameters to achieve maximum membrane flux and rejection are 207 kPa, 200 mg·L and 0.1769 m·s for applied pressure, feed concentration and cross flow velocity, respectively. Under these conditions, predicted responses are 41.33 × 10 m ·m ·s permeate flux and 98.7% rejection, which are in good agreement with the values obtained from experimental investigations (42.84 × 10 m ·m ·s and 98.82%). Therefore, we have demonstrated that the TiO -fly ash composite membrane as value added product is an efficient way to recycle fly ash and thus mitigate environmental hazards associated with the disposal of oily wastewaters.

关键词： TiO₂-fly ash membrane oily wastewater fouling microfiltration

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分形模型参数与粗糙度参数Rasub>关系的研究

潘玉良,吴立群,张云电

《中国工程科学》 2004年第6卷第5期页码 49-51

摘要：

介绍了W－M分形模型参数（D,G,γ）的物理含义，研究了分形参数（D,G,γ）与粗糙度参数Rasub>之间的联系，导出了分形参数（D,G,γ）与粗糙度参数Rasub>关系式，用数值分析拟合方法验证了关系式的正确性。

关键词： W－M分形模型分形参数粗糙度Rasub>

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Non-thermal plasma for exhaust gases treatment

Elvia ALVA R.,Marquidia PACHECO P.,Fernando GÓMEZ B.,Joel PACHECO P.,Arturo COLÍN C.

《机械工程前沿（英文）》 2015年第10卷第3期页码 301-305 doi: 10.1007/s11465-015-0344-z

摘要：

This article describes a study on a non-thermal plasma device to treat exhaust gases in an internal combustion engine. Several tests using a plasma device to treat exhaust gases are conducted on a Honda GX200-196 cm³ engine at different rotational speeds. A plasma reactor could be efficient in degrading nitrogen oxides and particulate matter. Monoxide and carbon dioxide treatment is minimal. However, achieving 1%–3% degradation may be interesting to reduce the emission of greenhouse gases.

关键词： plasma treatment NO_x CO CO₂ particulate matter vehicle

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Denitrification performance and sulfur resistance mechanism of Sm–Mn catalyst for low temperature NH-SCR

《化学科学与工程前沿（英文）》 2023年第17卷第5期页码 617-633 doi: 10.1007/s11705-022-2258-8

摘要： MnO_x and Sm–Mn catalysts were prepared with the coprecipitation method, and they showed excellent activities and sulfur resistances for the selective catalytic reduction of NO_x by NH₃ between 50 and 300 °C in the presence of excess oxygen. 0.10Sm–Mn catalyst indicated better catalytic activity and sulfur resistance. Additionally, the Sm doping led to multi-aspect impacts on the phases, morphology structures, gas adsorption, reactions process, and specific surface areas. Therefore, it significantly enhances the NO conversion, N₂ selectivity, and sulfur resistance. Based on various experimental characterization results, the reaction mechanism of catalysts and the effect of SO₂ on the reaction process about the catalysts were extensively explored. For 0.10Sm–Mn catalyst, manganese sulfate and sulfur ammonium cannot be generated broadly under the influence of SO₂ and the amount of surface adsorbed oxygen. The Bronsted acid sites strengthen significantly due to the addition of SO₂, enhancing the sulfur resistance of the 0.10Sm–Mn catalyst.

关键词： MnO_x Sm–Mn catalyst NH₃-SCR sulfur resistance

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Ductile extension of 3-D external circumferential cracks in pipe structures

Wuchao YANG, Xudong QIAN

《结构与土木工程前沿（英文）》 2011年第5卷第3期页码 294-303 doi: 10.1007/s11709-011-0115-9

摘要： This study investigates the ductile fracture resistance of 3-D external circumferential cracks in the wall of a steel pipe under remote tension, using a damage-mechanism model originally proposed by Gurson and Tvergaard. The ductile crack extension utilizes an element extinction technique implemented in the computational cell framework. The key parameter for the computational cell method, i.e., the initial porosity ratio , is calibrated using both the fracture resistance and the load-deformation responses obtained from fracture tests of multiple single-edge bend [SE(B)] specimens made of high-strength steel, HY80, which has a yield strength of 630 MPa. The fracture resistance along the 3-D semi-elliptical crack front is computed from the calibrated cell model. Based on the similarity concept in the near-tip stress-strain fields, this study demonstrates that an equivalent 2-D axi-symmetric model provides conservative estimations of the fracture resistance for 3-D circumferential cracks in pipes.

关键词： ductile fracture computational cell method G-T model J-R curve

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Adsorption characteristics of ciprofloxacin onto g-MoS2sub><

Zhenyu Yang, Rong Xing, Wenjun Zhou, Lizhong Zhu

《环境科学与工程前沿（英文）》 2020年第14卷第3期 doi: 10.1007/s11783-019-1218-0

摘要： The g-MoS2 coated composites (g-MoS2-BC) were synthesized. The coated g-MoS2 greatly increased the adsorption ability of biochar. The synergistic effect was observed for CIP adsorption on g-MoS2-RC700. The adsorption mechanisms of CIP on g-MoS2-BC were proposed. The g-MoS2 coated biochar (g-MoS2-BC) composites were synthesized by coating original biochar with g-MoS2 nanosheets at 300°C(BC300)/700°C (BC700). The adsorption properties of the g-MoS2-BC composites for ciprofloxacin (CIP) were investigated with an aim to exploit its high efficiency toward soil amendment. The specific surface area and the pore structures of biochar coated g-MoS2 nanosheets were significantly increased. The g-MoS2-BC composites provided more π electrons, which was favorable in enhancing the π-π electron donor-acceptor (EDA) interactions between CIP and biochar. As a result, the g-MoS2-BC composites showed faster adsorption rate and greater adsorption capacity for CIP than the original biochar. The coated g-MoS2 nanosheets contributed more to CIP adsorption on the g-MoS2-BC composites due to their greater CIP adsorption capacity than the original biochar. Moreover, the synergistic effect was observed for CIP adsorption on g-MoS2-BC700, and suppression effect on g-MoS2-BC300. In addition, the adsorption of CIP onto g-MoS2-BC composites also exhibited strong dependence on the solution pH, since it can affect both the adsorbent surface charge and the speciation of contaminants. It was reasonably suggested that the mechanisms of CIP adsorption on g-MoS2-BC composites involved pore-filling effects, π-π EDA interaction, electrostatic interaction, and ion exchange interaction. These results are useful for the modification of biochar in exploiting the novel amendment for contaminated soils.

关键词： Adsorption Ciprofloxacin g-MoS₂ nanosheets Biochar Soil remediation

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g-CN-coated MnO hollow nanorod cathode for stable aqueous Zn-ion batteries

《化学科学与工程前沿（英文）》 2023年第17卷第2期页码 217-225 doi: 10.1007/s11705-022-2214-7

摘要： Aqueous zinc-ion batteries are attracting considerable attention because of their high safety compared with conventional lithium-ion batteries. Manganese-based materials have been widely developed for zinc-ion batteries cathode owning to their low cost, high security and simple preparation. However, the severe volume expansion and poor stability during charging and discharging limit the further development of manganese-based cathodes. Herein, superior α-MnO₂@g-C₃N₄ was successfully prepared for stable zinc-ion batteries (ZIBs) cathode by introducing g-C₃N₄ nanosheets. Compared with pure α-MnO₂, α-MnO₂@g-C₃N₄ has a specific capacity of 298 mAh·g^–1 at 0.1 A·g^–1. Even at 1 A·g^–1, the α-MnO₂@g-C₃N₄ still retains 100 mAh·g^–1 (83.4% retention after 5000 cycles), implying its excellent cycling stability. The α-MnO₂@g-C₃N₄-based cathode has the highest energy density (563 Wh·kg^–1) and power energy density (2170 W·kg^–1). This work provides new avenues for the development of a wider range of cathode materials for ZIBs.

关键词： α-MnO₂ hollow nanorods g-C₃N₄ heterojunction aqueous Zn-ion batteries

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Al2sub>O3sub>-Mxsub>Oysub>硬面陶瓷涂层的喷焊制备及性能研究

王飚,王宇栋,李慧玲,张自华

《中国工程科学》 2002年第4卷第9期页码 75-80

摘要：

在碳钢母材上，用氧乙炔焰喷焊镍包铝合金粉末制取预涂层，喷焊50% Al2sub>O3sub>+50% Ni的复合粉末制取过渡层，用等离子喷焊Al2sub>O3sub> - Mxsub>Oysub>复合粉末制取最终涂层。

关键词： Al2sub>O3sub>-Mxsub>Oysub> 涂层等离子抗腐蚀抗磨损

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基于实时CT扫描技术的CO2sub>和N2sub>交替注入条件下煤吸附膨胀和解吸收缩规律研究 Article

张广磊, P.G. Ranjith, Herbert E. Huppert

《工程（英文）》 2022年第18卷第11期页码 88-95 doi: 10.1016/j.eng.2022.03.010

摘要：

深部煤层是分布最广泛的适宜二氧化碳（CO2sub>）地质封存的地层之一，且通常位于大型CO2sub>排放源附近。将CO2sub>注入到煤层中具有巨大的CO2sub>封存潜力，同时可以提高煤层气的采收率（CO2sub>-ECBM）。本文采用原位同步辐射X射线显微CT扫描技术，首次在原位条件下直接证明了注入氮气（N2sub>）可以置换解吸CO2sub>并减小因CO2sub>吸附引起的煤基质膨胀研究结果表明，煤层中注入经过简单处理的烟道气（主要成分为N2sub>和CO2sub>），是技术上可行的CO2sub>-ECBM 替代方案。其次，N2sub>的存在可以使煤层保持较高的渗透率，实现长期CO2sub>注入封存和煤层气增产。

关键词： CCS CO2sub>-ECBM 碳中和 X 射线成像煤渗透率

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Preparation and lithium storage performances of g-C

Zhengxu BIAN, Zehua TANG, Jinfeng XIE, Junhao ZHANG, Xingmei GUO, Yuanjun LIU, Aihua YUAN, Feng ZHANG, Qinghong KONG

《能源前沿（英文）》 2020年第14卷第4期页码 759-766 doi: 10.1007/s11708-020-0810-0

摘要： As the anode material of lithium-ion battery, silicon-based materials have a high theoretical capacity, but their volume changes greatly in the charging and discharging process. To ameliorate the volume expansion issue of silicon-based anode materials, g-C N /Si nanocomposites are prepared by using the magnesium thermal reduction technique. It is well known that g-C N /Si nanocomposites can not only improve the electronic transmission ability, but also ameliorate the physical properties of the material for adapting the stress and strain caused by the volume expansion of silicon in the lithiation and delithiation process. When g-C N /Si electrode is evaluated, the initial discharge capacity of g-C N /Si nanocomposites is as high as 1033.3 mAh/g at 0.1 A/g, and its reversible capacity is maintained at 548 mAh/g after 400 cycles. Meanwhile, the improved rate capability is achieved with a relatively high reversible specific capacity of 218 mAh/g at 2.0 A/g. The superior lithium storage performances benefit from the unique g-C N /Si nanostructure, which improves electroconductivity, reduces volume expansion, and accelerates lithium-ion transmission compared to pure silicon.

关键词： magnesium thermal reduction g-C₃N₄/Si nanocomposites volume expansion electroconductivity lithium-ion battery

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Metal-organic framework-based CO

Yujie Ban, Meng Zhao, Weishen Yang

《化学科学与工程前沿（英文）》 2020年第14卷第2期页码 188-215 doi: 10.1007/s11705-019-1872-6

摘要： A low-carbon economy calls for CO capture technologies. Membrane separations represent an energy-efficient and environment-friendly process compared with distillations and solvent absorptions. Metal-organic frameworks (MOFs), as a novel type of porous materials, are being generated at a rapid and growing pace, which provide more opportunities for high-efficiency CO capture. In this review, we illustrate a conceptional framework from material design and membrane separation application for CO capture, and emphasize two importance themes, namely (i) design and modification of CO -philic MOF materials that targets secondary building units, pore structure, topology and hybridization and (ii) construction of crack-free membranes through chemical epitaxy growth of active building blocks, interfacial assembly, ultrathin two-dimensional nanosheet assembly and mixed-matrix integration strategies, which would give rise to the most promising membrane performances for CO capture, and be expected to overcome the bottleneck of permeability-selectivity limitations.

关键词： CO₂ capture CO₂-philic MOFs crack-free membranes

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A CO and CO

Guoxing Chen, Marc Widenmeyer, Binjie Tang, Louise Kaeswurm, Ling Wang, Armin Feldhoff, Anke Weidenkaff

《化学科学与工程前沿（英文）》 2020年第14卷第3期页码 405-414 doi: 10.1007/s11705-019-1886-0

摘要： A series of novel dense mixed conducting ceramic membranes based on K NiF -type (La Ca ) (Ni Cu )O was successfully prepared through a sol-gel route. Their chemical compatibility, oxygen permeability, CO and CO tolerance, and long-term CO resistance regarding phase composition and crystal structure at different atmospheres were studied. The results show that higher Ca contents in the material lead to the formation of CaCO . A constant oxygen permeation flux of about 0.63 mL·min ·cm at 1173 K through a 0.65 mm thick membrane was measured for (La Ca ) (Ni Cu )O , using either helium or pure CO as sweep gas. Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO concentration. The membrane showed excellent chemical stability towards CO for more than 1360 h and phase stability in presence of CO for 4 h at high temperature. In addition, this membrane did not deteriorate in a high-energy CO plasma. The present work demonstrates that this (La Ca ) (Ni Cu )O membrane is a promising chemically robust candidate for oxygen separation applications.

关键词： K₂NiF₄ structure oxygen permeation membrane CO₂ and CO resistances CO₂ plasma resistance long-term robustness

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Tuning nitrogen defects and doping sulfur in carbon nitride for enhanced visible light photocatalytic activity

《化学科学与工程前沿（英文）》 2023年第17卷第1期页码 93-101 doi: 10.1007/s11705-022-2175-x

摘要： Defect construction and heteroatom doping are effective strategies for improving photocatalytic activity of carbon nitride (g-C₃N₄). In this work, N defects were successfully prepared via cold plasma. High-energy electrons generated by plasma can produce N defects and embed sulfur atoms into g-C₃N₄. The N defects obviously promoted photocatalytic degradation performance that was 7.5 times higher than that of pure g-C₃N₄. The concentration of N defects can be tuned by different power and time of plasma. With the increase in N defects, the photocatalytic activity showed a volcanic trend. The g-C₃N₄ with moderate concentration of N defects exhibited the highest photocatalytic activity. S-doped g-C₃N₄ exhibited 11.25 times higher photocatalytic activity than pure g-C₃N₄. It provided extra active sites for photocatalytic reaction and improved stability of N defects. The N vacancy-enriched and S-doped g-C₃N₄ are beneficial for widening absorption edge and improving the separation efficiency of electron and holes.

关键词： g-C₃N₄ nitrogen defect sulfur doping photodegradation plasma

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Fracture resistance on aggregate bridging crack in concrete

ZHANG Xiufang, XU Shilang

《结构与土木工程前沿（英文）》 2007年第1卷第1期页码 63-70 doi: 10.1007/s11709-007-0006-2

摘要： Fracture toughening exhibited in quasi-brittle materials such as concrete is often mainly related to the action of aggregate bridging, which leads to the presence of a fracture process zone ahead of stress-free cracks in such materials. In this investigation, the fracture resistance induced by aggregate bridging, denoted by GI-bridging, is the primary focus. In order to quantitatively determine it, a general analytical formula is firstly developed, based on the definition of fracture energy by Hillerborg. After this, we further present the calculated procedures of determining this fracture resistance from the recorded load vs. crack opening displacement curve. Then, both numerical simulations and fracture experiments are performed on concrete three-point bending beams. Utilizing the obtained load against crack opening displacement curve, the value of G at any crack extension as well as the change of G with the crack extension is examined. It is found that G will firstly increase with the development of crack and then stay constant once the initial crack tip opening displacement reaches the characteristic crack opening displacement w0. The effects of material strength and specimen depth on this fracture resistance are also investigated. The results reveal that the values of G of different specimens at any crack propagation are strongly associated with the values of fracture energy of specimens. If the values of fracture energy between different specimens are comparable, the differences between G are ignored. Instead, if values of fracture energy are different, the G will be different. This shows that for specimens with different strengths, G will change greatly whereas for specimens that are different in depth, whether GI-bridging exhibits size effect depends on whether the fracture energy of specimens considered in the calculation of G is assumed to be a size-dependent material parameter.

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标题作者时间类型操作

Correlation between tension softening relation and crack extension resistance in concrete

Xiufang ZHANG , Shilang XU ,

期刊论文

Preparation and characterization of hydrothermally engineered TiO

Kanchapogu Suresh, G. Pugazhenthi, R. Uppaluri

期刊论文

分形模型参数与粗糙度参数Rasub>关系的研究

潘玉良,吴立群,张云电

期刊论文

Non-thermal plasma for exhaust gases treatment