Structural and mechanical properties of geopolymers made of aluminosilicate powder with different SiO2/Al2O3 ratio: Molecular dynamics simulation and microstructural experimental study
作者:
Wang, Rui;Wang, Jingsong* ;Dong, Teng;Ouyang, Gaoshang
期刊:
Construction and Building Materials ,2020年240:117935- ISSN:0950-0618
通讯作者:
Wang, Jingsong
作者机构:
[Wang, Rui] Univ South China, Sch Resource Environm & Safety Engn, Hengyang 421001, Hunan, Peoples R China.;[Ouyang, Gaoshang; Wang, Jingsong; Dong, Teng] Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.;[Wang, Jingsong] Univ South China, Yangtze Delta Res Inst, Zhuji 311800, Zhejiang, Peoples R China.
通讯机构:
[Wang, Jingsong] U;Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.
关键词:
Geopolymer;Aluminosilicate powder;SiO2/Al2O3 ratio;Molecular dynamics simulation;Structural properties;Mechanical properties
摘要:
In this study, the impacts of different SiO2/Al2O3 ratio on the molecular structural and mechanical properties of geopolymer were investigated by molecular dynamics and experiment. Complex composition of raw materials may affect the analysis of geopolymer gels. Therefore, pure aluminosilicate powder with different SiO2/Al2O3 ratio were synthesized by sol-gel method firstly. Then the prepared powder mixed with the activating agent of NaOH and sodium silicate to prepare geopolymer. After 28d curing age, chemical composition and crystalline phase of geopolymer were characterized by X-ray fluorescence(XRF) and X-ray Diffraction (XRD) respectively. Based on the above characterization results of geopolymer gel, different SiO2/Al2O3 ratio of molecular models were built. Finally, molecular dynamics were performed on the molecular models to study energy and temperature, simulated XRD, radial distribution function (RDF), distribution of bond length and bond angle and elastic modulus. Results showed that with the increases of SiO2/Al2O3 ratio, both stability of molecular structure and mechanical properties of geopolymer were decreased. © 2019 Elsevier Ltd
语种:
英文
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Optimal Receiver Placement for K-barrier Coverage in Passive Bistatic Radar Sensor Networks
作者:
Chen, Jiaoyan;Yang, Laurence T.;Deng, Xianjun* ;Hong, Xianggong;Yi, Lingzhi
期刊:
ACM Transactions on Internet Technology ,2020年20(3):24:1-24:23 ISSN:1533-5399
通讯作者:
Deng, Xianjun
作者机构:
[Hong, Xianggong; Chen, Jiaoyan] Nanchang Univ, Sch Informat & Engn, Nanchang 330031, Jiangxi, Peoples R China.;[Yang, Laurence T.] St Francis Xavier Univ, Dept Comp Sci, Antigonish, NS B2G 2W5, Canada.;[Deng, Xianjun] Univ South China, Sch Elect Engn, Hengyang 421001, Hunan, Peoples R China.;[Yi, Lingzhi] Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.
通讯机构:
[Deng, Xianjun] U;Univ South China, Sch Elect Engn, Hengyang 421001, Hunan, Peoples R China.
关键词:
K-barrier coverage;minimum receiver problem;Passive bistatic radar network
摘要:
The improvement of coverage quality in the construction of multiple-barrier coverage is a critical problem in a wireless sensor network. In this article, we investigate the K-barrier coverage construction problem in passive bistatic radar sensor networks. In contrast to traditional bistatic radar networks, the transmitters in a passive bistatic radar network are predeployed and noncooperative. To construct K barriers, we need to deploy receivers that couple with predeployed transmitters to build continuous barriers. In this work, we focus on the minimum number of receivers problem of constructing K-barrier coverage, where the minimum number of receivers is based on the predeployed transmitters. To handle this problem, we first investigate the optimal placement of receivers between adjacent transmitters for a sub-barrier formation and then determine the optimal placement of receivers for the one-barrier construction. For multiple-barrier coverage construction, we introduce a weighted transmitter graph (WTG) to describe the relation among different transmitters, where the weight in the graph is the minimum number of receivers needed for these two transmitters for a sub-barrier formation. Based on WTG, the minimum receivers problem changes to a problem of how to find K-disjoint paths with the minimum total weight in the graph. For large-scale networks, we also propose two efficient heuristic algorithms to solve the corresponding problem. Finally, we conduct extensive experiments to validate the correctness and the efficiency of the proposed algorithms. © 2020 ACM.
语种:
英文
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Fractal discrete fracture network model for the analysis of radon migration in fractured media
作者:
Feng, Shengyang* ;Wang, Hanqing;Cui, Yu;Ye, Yongjun;Liu, Yong* ;...
期刊:
Computers and Geotechnics ,2020年128:103810- ISSN:0266-352X
通讯作者:
Feng, Shengyang;Liu, Yong
作者机构:
[Cui, Yu; Ye, Yongjun; Yang, Rong; Feng, Shengyang; Wang, Hong; Liu, Yong; Feng, SY; Li, Xiangyang] Univ South China, Sch Resource Environm & Safety Engn, Hengyang 421001, Hunan, Peoples R China.;[Wang, Hanqing] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Cui, Yu] Hunan Prov Engn Technol Res Ctr Uranium Tailings, Hengyang 421001, Peoples R China.;[Li, Xiangyang] Hunan Prov Engn Res Ctr Radioact Control Technol, Hengyang 421001, Peoples R China.
通讯机构:
[Feng, SY; Liu, Y] U;Univ South China, Sch Resource Environm & Safety Engn, Hengyang 421001, Hunan, Peoples R China.
关键词:
Discrete fracture network;Fractal theory;Radon migration;Fractal dimension
摘要:
A novel model combined with fractal theory and the discrete fracture network (DFN) model is proposed to simulate radon migration in fractured media. In the novel model, the fracture center and length distribution are determined by a first-order model, and the fracture orientations are modeled with the von Mises-Fisher distribution. The model is further developed into a computer software that can calculate the radon diffusion coefficient and exhalation rate of fractured media. An outcrop map is used to validate the ability of the model to describe complex fractures, and radon migration in natural fractures at an outcrop site is predicted using the model. Results show that the model has good reliability and robustness. Evaluation of the representative elementary volume (REV) indicates the existence of REV during the modeling of radon migration in fracture networks. Following an exponential law, REV size decreases with the increase in the length exponent. © 2020
语种:
英文
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An investigation on physical, mechanical, leaching and radiation shielding behaviors of barite concrete containing recycled cathode ray tube funnel glass aggregate
作者:
Liu, Hualiang;Shi, Jianjun;Qu, Huiqiong;Ding, Dexin*
期刊:
Construction and Building Materials ,2019年201:818-827 ISSN:0950-0618
通讯作者:
Ding, Dexin
作者机构:
[Ding, Dexin; Shi, Jianjun; Liu, Hualiang] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Ding, Dexin; Shi, Jianjun; Liu, Hualiang] Cent S Univ, Sch Resources & Safety Engn, Changsha 410083, Hunan, Peoples R China.;[Ding, Dexin; Qu, Huiqiong] Univ South China, Nucl Resources Engn Coll, Hengyang 421001, Peoples R China.
通讯机构:
[Ding, Dexin] U;Univ South China, Nucl Resources Engn Coll, Hengyang 421001, Peoples R China.
关键词:
Waste cathode ray tube;Funnel glass;Barite concrete;Physical and mechanical behaviors;Dry shrinkage;Alkali-silica reaction expansion;Lead leaching;Radiation shielding;XCOM;MCNP
摘要:
In order to explore the feasibility of using hazardous waste cathode ray tube (CRT) funnel glass to replace high density mineral aggregates in the radiation shielding concrete, various barite concrete samples were prepared with portland cement, ground funnel glass sand as the substitute for barite aggregates, and fly ash as mineral admixtures, and the rates of funnel glass for fine and coarse (5–10 mm) barite aggregate were 25%, 50%, 75%, 100% and 10%, 20%, 30%, respectively. The work performance, mechanical properties, dry shrinkage, alkali-silica reaction (ASR) expansion and lead leaching were investigated, and the γ-ray attenuation coefficients were obtained by experiment, XCOM program and MCNP code. The results show that the slump, ASR expansion and lead leaching of the concrete increase while its apparent density, mechanical properties, dry shrinkage, and γ-ray shielding properties decrease with the increase of the rate of funnel glass. Adding fly ash to the concrete can inhibit the leaching of Pb, and reduce the ASR expansion. The concrete samples with 25–50% fine funnel glass sand or 10–20% 5–10 mm coarse aggregate have good performances. The results show that it's efficient, economical and environmental-benign to use funnel glass to produce the high density radiation shielding concrete. © 2019 Elsevier Ltd
语种:
英文
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Experimental Study on the Mechanical Properties and Crack Propagation of Jointed Rock Mass Under Impact Load
作者:
Zeng, Sheng;Jiang, Bowei;Sun, Bing
期刊:
Geotechnical and Geological Engineering ,2019年37(6):5359-5370 ISSN:0960-3182
通讯作者:
Sun, Bing(sunbingnh@126.com)
作者机构:
[Zeng, Sheng; Jiang, Bowei] School of Resource Environment and Safety Engineering, University of South China, Hengyang;421001, China;[Sun, Bing] School of Civil Engineering, University of South China, Hengyang;[Zeng, Sheng; Jiang, Bowei; Sun, Bing] 421001, China
通讯机构:
[Sun, B.] S;School of Civil Engineering, University of South China, Hengyang, China
关键词:
Crack propagation;Dynamic deformation;Impact load;Jointed rock mass;Rock mechanics
摘要:
A drop hammer impact test on jointed rock masses is carried out in this study. According to the analysis of the effect of different joints on the strength, the deformation and the damage of jointed rock masses, the law of the mechanical properties and crack propagation of jointed rock masses is observed under impact load. First, when the dip angle and the number of the joint are greater, the dynamic bearing capacity of rock masses will be weaker. Meanwhile the deformation and the damage of rock masses will increase. Then, when the impact load is small, the dynamic compression deformation of jointed rock mass is mainly due to the normal closure of joints. After the impact load increased, more microcracks are produced around the joints. These cracks will gradually spread along the joints and finally lead to the damage of jointed rock masses. Besides, the joint can increase the stress waves energy dissipation and weaken the propagation of the stress waves in the rock mass. The study provides a reference for the dynamic analysis of fractured rock masses and the excavation support of surrounding rock mass in deep mining of mines. © 2019, Springer Nature Switzerland AG.
语种:
英文
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Synthesis of polyethylenimine/graphene oxide for the adsorption of U(VI) from aqueous solution
作者:
Liu, Hongjuan* ;Zhou, Yuancheng;Yang, Yibo;Zou, Ke;Wu, Renjie;...
期刊:
Applied Surface Science ,2019年471:88-95 ISSN:0169-4332
通讯作者:
Liu, Hongjuan;Xie, Shuibo
作者机构:
[Xia, Ke; Liu, Hongjuan; Yang, Yibo; Wu, Renjie; Zhou, Yuancheng; Zou, Ke] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Xie, Shuibo; Liu, HJ] Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium Mi, Hengyang 421001, Peoples R China.;[Xie, Shuibo] Univ South China, Hunan Prov Key Lab Pollut Control & Resources Reu, Hengyang 421001, Peoples R China.
通讯机构:
[Liu, HJ; Xie, SB] U;Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium Mi, Hengyang 421001, Peoples R China.
关键词:
Adsorption;Graphene oxide;Polyethyleneimine;U(VI)
摘要:
Polyethyleneimine (PEI)/graphene oxide (GO) was synthesized through a self-assembly method with the formation of the amide group –CONH– between –NH 2 on PEI and –COOH on GO. The formation was confirmed by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The oxygen- and nitrogen-containing functional groups of PEI/GO were involved in the adsorption of U(VI), as determined under the FT-IR and XPS analyses of PEI/GO and U(VI)-adsorbed PEI/GO. The pH, contact times, and initial concentration, which are the factors influencing the removal of U(VI), were investigated. The adsorption of U(VI) onto PEI/GO was fitted well with the pseudo-second-order kinetic model and Langmuir isotherm model. The maximum sorption capacities of U(VI) on PEI/GO (145.14 mg·g −1 ) at pH = 7 and T = 303 K were higher than that of U(VI) on GO (94.61 mg·g −1 ). This study provides a novel and simple method for synthesizing GO derivatives with efficient adsorption performances of U(VI) from aqueous solution. © 2018
语种:
英文
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废玻璃粉混凝土力学性能研究
作者:
李松;焦楚杰;甘元初
期刊:
工程科学与技术 ,2019年51(5):199-205 ISSN:2096-3246
通讯作者:
Jiao, Chujie(jiaochujie@sina.com)
作者机构:
[李松; 焦楚杰] School of Civil Eng., Guangzhou Univ., Guangzhou;510006, China;[甘元初] School of Civil Eng., Univ. of South China, Hengyang;421001, China;[李松; 焦楚杰] 510006, China
通讯机构:
[Jiao, C.] S;School of Civil Eng., Guangzhou Univ., Guangzhou, China
关键词:
废玻璃粉混凝土;抗压强度;劈拉强度;弹性模量;泊松比
摘要:
为实现城市固体垃圾废玻璃资源化,以不同掺量废玻璃粉取代水泥,按标准试验方法研究了C30与C50两种强度等级的废玻璃粉混凝土(waste glass powder concrete,WGPC)各类强度变形指标.试验发现:C30WGPC在废玻璃粉掺量在25%~30%之间时,抗压强度同比降低幅度最大,达到了21.7%,C30WGPC替代水泥掺量可在0~25%以内,C50WGPC最佳掺量可大于25%;废玻璃粉的掺入改善了混凝土的脆性性能,随着试配强度等级的提高脆性会有所增大,C50WGPC轴压强度与抗压强度关系式可以近似地进行普通混凝土两者关系的换算;另外,WGPC弹性模量公式适用于计算普通混凝土的弹性模量,WGPC泊松比与普通混凝土泊松比相差不大.试验结果表明废玻璃粉可较大掺量试配强度等级较高的混凝土,并为WGPC的工程应用提供基础参数.
语种:
中文
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氧化石墨烯及其复合材料对水中放射性核素的吸附
作者:
刘红娟;吴仁杰;谢水波;刘迎九
期刊:
材料工程 ,2019年47(10):22-32 ISSN:1001-4381
通讯作者:
Xie, Shui-Bo(xiesbmr@263.net)
作者机构:
[刘红娟; 吴仁杰] Institute of Nuclear Science and Technology, University of South China, Hengyang;Hunan;421001, China;[谢水波] Key Discipline Laboratory for National Defence for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang;[刘迎九] Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang
通讯机构:
[Xie, S.-B.] K;Key Discipline Laboratory for National Defence for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang, Hunan, China
关键词:
氧化石墨烯;放射性核素;吸附;改性材料;废水
摘要:
在核能和核技术的快速发展过程及应用中产生了大量放射性废水,其对生态环境会造成潜在的污染,因此对放射性废水处理技术的研究对保护环境有着重要的意义。氧化石墨烯及其复合材料具有比表面积高、官能团丰富、吸附能力强、化学稳定性好等优点,在放射性废水处理领域受到广泛关注。本文综述了近年来有关氧化石墨烯及其复合材料对水中放射性核素吸附的研究现状及进展,介绍了氧化石墨烯及其复合材料对放射性核素的吸附容量、吸附等温模型、吸附热力学、影响因素和吸附机理。最后分析了氧化石墨烯及其复合材料处理放射性核素在辐射稳定性和高吸附选择性等方面面临的问题和挑战,探讨了推动该类材料今后实际放射性废水处理中工程应用的重点研究方向,如完善的产业体系和积极研发相匹配的成套水处理工艺及设备等。
语种:
中文
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The study of migration velocity of Cs-135 and Se-79 in intact rock(Open Access)
作者:
H LING;L CHEN;W M CHEN;L YUN
期刊:
IOP Conference Series: Materials Science and Engineering ,2019年592(1):371-377 ISSN:1757-8981
作者机构:
[L YUN; W M CHEN; H LING; L CHEN] Beijing Research Institute of Uranium Geology, CNNC, Beijing, 100029, China;[H LING] Hunan Provincial Key Laboratory of Pollution Control and Resources Technology, University of South China, Hengyang, 421001, China
会议名称:
第二届制造技术,材料和化学工程国际学术会议(MTMCE 2019)
会议时间:
2019-06-14
会议地点:
中国湖北武汉
会议论文集名称:
Proceedings of 2019 2nd International Conference on Manufacturing Technology, Materials and Chemical Engineering (MTMCE 2019)
摘要:
The migration characteristics of highly mobile nuclides in natural barrier are the key concerns in the long-term safety assessment of geological disposal facilities. This paper focused on typical granite in Beishan area for geological disposal of high-level radioactive waste, and established a computational model for the release and migrate of nuclides after closure of repository by GoldSim. The migration characteristics of Cs-135 and Se-79 were analyzed by Monte Carlo stochastic simulation. The results show that the migration characteristics of Cs-135 and Se-79 in intact rock are direct influenced by hydraulic conductivity and hydraulic gradient, the migration velocity are 2.47×10<sup>-4</sup>m/a and 9.61×10<sup>-4</sup>m/a when the hydraulic conductivity correspond to 5.74 ×10<sup>-9</sup> m/s. The analysis of the results shows that the migration characteristics can provide feedback guidance for the site selection and design of the disposal repository.<br/> ©Published under licence by IOP Publishing Ltd.
语种:
中文
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Thermal driven flows inside a square enclosure saturated with nanofluids: Convection heat functions and transfer rate revisions from a homogenous model
作者:
Wang, Lei;Zhang, Dong-Dong;Zhao, Fu-Yun* ;Liu, Di;Wang, Han-Qing
期刊:
Numerical Heat Transfer, Part B: Fundamentals ,2019年75(4):265-288 ISSN:1040-7790
通讯作者:
Zhao, Fu-Yun
作者机构:
[Wang, Lei; Zhang, Dong-Dong; Zhao, Fu-Yun] Wuhan Univ, Minist Educ, Key Lab Hydraul Machinery Transients, Wuhan, Hubei, Peoples R China;[Wang, Lei; Zhang, Dong-Dong; Zhao, Fu-Yun] Wuhan Univ, Hubei Key Lab Waterjet Theory & New Technol, Wuhan, Hubei, Peoples R China;[Wang, Lei; Zhang, Dong-Dong; Zhao, Fu-Yun] Wuhan Univ, Sch Power & Mech Engn, Wuhan 430072, Hubei, Peoples R China;[Liu, Di] China Univ Petr, Coll Pipeline & Civil Engn, Qingdao, Shandong, Peoples R China;[Wang, Han-Qing] Univ South China, Sch Civil Engn, Hengyang, Hunan, Peoples R China
通讯机构:
[Zhao, Fu-Yun] W;Wuhan Univ, Sch Power & Mech Engn, Wuhan 430072, Hubei, Peoples R China.
摘要:
In former theoretical researches of nanofluid flows, numerical investigations could not agree with experimental observations, particularly regarding whether the mixing nanoparticles will enhance or deteriorate the heat transfer. In the present work, thermal driven buoyancy flows of nanofluids in a square enclosure were modeled by the use of homogeneous assumptions and the effective kinematic viscosity and thermal conductivity formulas. Thoroughly developed heat transfer coefficient is subsequently proposed, aiming to critically evaluate the performance of nanofluid heat transport. Numerical results are presented over a wide range of thermal Rayleigh number (10(3) <= Ra <= 10(6)) and nanoparticles volume fraction (0.001 <= phi <= 0.04). Present modeling results accurately predict both the enhancement and deterioration of the natural convection heat transfer, fully validated by former experimental observations. Overall, mathematical models and Nusselt number definitions proposed in the present work effectively enhance the reliability of numerical modeling researches on the nanofluid heat transfer. Present clarification research on the Nusselt unifications could benefit future development of thermal carrier fluid enhanced by nano-particles.
语种:
英文
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Wind driven “pumping” fluid flow and turbulent mean oscillation across high-rise building enclosures with multiple naturally ventilated apertures
作者:
Zhong, Huai-Yu;Zhang, Dong-Dong;Liu, Yang;Liu, Di;Zhao, Fu-Yun* ;...
期刊:
Sustainable Cities and Society ,2019年50:101619- ISSN:2210-6707
通讯作者:
Zhao, Fu-Yun
作者机构:
[Zhong, Huai-Yu; Zhao, Fu-Yun; Liu, Yang; Zhang, Dong-Dong] Wuhan Univ, Minist Educ, Key Lab Hydraul Machinery Transients, Wuhan, Hubei, Peoples R China.;[Zhong, Huai-Yu; Zhao, Fu-Yun; Liu, Yang; Zhang, Dong-Dong] Wuhan Univ, Hubei Key Lab Waterjet Theory & New Technol, Wuhan, Hubei, Peoples R China.;[Zhong, Huai-Yu; Zhao, Fu-Yun; Liu, Yang; Zhang, Dong-Dong] Wuhan Univ, Sch Power & Mech Engn, Dong Hu Southern Rd, Wuhan 430072, Hubei, Peoples R China.;[Liu, Di] China Univ Petr, Coll Pipeline & Civil Engn, Qingdao, Shandong, Peoples R China.;[Li, Yuguo] Univ Hong Kong, Dept Mech Engn, Pokfulam Rd, Hong Kong, Peoples R China.
通讯机构:
[Zhao, Fu-Yun] W;Wuhan Univ, Sch Power & Mech Engn, Dong Hu Southern Rd, Wuhan 430072, Hubei, Peoples R China.
关键词:
Full CFD simulation;Single-sided ventilation;Vortex shedding;Contaminant dispersion
摘要:
This paper presents a study on the impact of incoming wind velocity magnitudes and horizontal aperture separations on natural ventilation flows in a single-sided wind-driven naturally ventilated building with two apertures (SS2) on the rear wall or the front wall. Both the velocity fields and the contaminant concentration fields were simulated and investigated. The present study is based on CFD simulations with unsteady Reynolds-averaged Navier-Stokes (URANS) SST k-ω model. A vortex shedding flow mechanism has been identified when the two apertures are mounted either on the rear wall or on the front wall, through which the air flow oscillates at a certain rate. CFD results further demonstrate that the oscillating frequency increases with the incoming wind magnitude and is nearly independent of the horizontal aperture separations. For the same building configuration, the root mean square (r.m.s) of the non-dimensional ventilation flow rate is independent of the incoming wind speed, whereas it decreases when the horizontal aperture separation is reduced. The time-averaged contaminant concentration fields also validated the different ventilation performance of different aperture configurations. This novel ventilation mechanism could be applied to alleviate the poor ventilation performance of buildings with single-sided apertures.
语种:
英文
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磁性介孔TiO_2/氧化石墨烯复合材料的制备及其对U(Ⅵ)的吸附
作者:
毕玉玺;凌辉;唐振平;谢严兴
期刊:
复合材料学报 ,2019年36(9):2176-2186 ISSN:1000-3851
通讯作者:
Tang, Zhenping(1578988350@qq.com)
作者机构:
[毕玉玺; 唐振平; 谢严兴] Hunan Provincial Key Laboratory of Pollution Control and Resources Technology, University of South China, Hengyang;421001, China;[凌辉] CNNC, Beijing Research Institute of Uranium Geology, Beijing;100029, China;[毕玉玺; 唐振平; 谢严兴] 421001, China
通讯机构:
[Tang, Z.] H;Hunan Provincial Key Laboratory of Pollution Control and Resources Technology, University of South China, Hengyang, China
关键词:
氧化石墨烯(GO);磁性介孔TiO2;吸附;解吸;共存离子
摘要:
以氧化石墨烯(GO)、纳米Fe_3O_4、钛酸四丁酯(TBOT)为原料,合成了磁性介孔TiO_2/GO(Fe_3O_4 @TiO_2/GO)复合材料,用其处理浓度为10mg·L~(-1)的含U(Ⅵ)废水。研究了Fe_3O_4@TiO_2/GO复合材料中GO含量、溶液初始pH值、Fe_3O_4@TiO_2/GO复合材料投加量、反应时间、U(Ⅵ)初始浓度及共存离子对U(Ⅵ)吸附的影响。结果表明:在pH值为6、GO质量分数为60wt%、Fe_3O_4@TiO_2/GO复合材料投加量为10mg的条件下, Fe_3O_4@TiO_2/GO复合材料对U(Ⅵ)的吸附效果最佳,较同等条件下磁性介孔Fe_3O_4@TiO_2复合材料和GO的吸附量分别高了10.99mg·g~(-1)和1.91mg·g~(-1)。Fe_3O_4@TiO_2/GO复合材料对U(Ⅵ)的吸附180min即达到平衡,准二级动力学模型和Freundlich吸附等温模型能很好地描述其吸附过程。解吸实验表明,经5次吸附-解吸后, U(Ⅵ)的吸附率仍高达90.86%,说明Fe_3O_4@TiO_2/GO复合材料具有较高的循环利用性能。
语种:
中文
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A wind-driven gas exchange rate model
作者:
Duan, Zhiyong*
期刊:
Environmental Engineering Science ,2019年36(3):344-349 ISSN:1092-8758
通讯作者:
Duan, Zhiyong
作者机构:
[Duan, Zhiyong] Univ South China, Sch Civil Engn, Hengyang 421000, Hunan, Peoples R China.
通讯机构:
[Duan, Zhiyong] U;Univ South China, Sch Civil Engn, Hengyang 421000, Hunan, Peoples R China.
关键词:
gas exchange rate;water quality modeling;wind-driven
摘要:
The dissolved oxygen is a major factor influencing the water quality of a water body. The gas exchange rate determines the speed that the low soluble gases, including dissolved oxygen, transfer from atmosphere to water. The wind-driven gas exchange rate model is important for the water quality modeling in water bodies such as lakes and estuaries when the wind is the predominant factor. Although empirical formulae have been developed for wind-driven gas exchange rate, they cannot explain the mechanisms of wind-driven gas exchange rate. The empirical formulae are normally limited in their applicability due to the specific experimental conditions under which they were established. This study is to develop a mechanistic wind-driven gas exchange rate model for the general application ranges. This mechanistic wind-driven gas exchange rate model correlates the gas exchange rate with the hydrodynamic parameters based on the surface renewal mechanism and the two-film transfer mechanism. The gas exchange rate values predicted with this model show reasonable agreements with the experimental data in the wind-driven gas exchange systems. This model can be applied for water bodies with wind blowing over the water surface as the predominant factor influencing the exchange rate of the low soluble gases. © 2019 Mary Ann Liebert, Inc., publishers.
语种:
英文
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Sulfate attack resistance of sustainable concrete incorporating various industrial solid wastes
作者:
Tang, Zhuo;Li, Wengui* ;Ke, Guojun;Zhou, John L.;Tam, Vivian W. Y.
期刊:
Journal of Cleaner Production ,2019年218:810-822 ISSN:0959-6526
通讯作者:
Li, Wengui
作者机构:
[Tang, Zhuo; Li, Wengui; Zhou, John L.] Univ Technol Sydney, Ctr Built Infrastruct Res, Sch Civil & Environm Engn, Sydney, NSW 2007, Australia.;[Ke, Guojun] Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.;[Tam, Vivian W. Y.] Western Sydney Univ, Sch Comp Engn & Math, Penrith, NSW 2751, Australia.
通讯机构:
[Li, Wengui] U;Univ Technol Sydney, Ctr Built Infrastruct Res, Sch Civil & Environm Engn, Sydney, NSW 2007, Australia.
关键词:
Sustainable concrete;Waste glass powder;Coal gangue powder;Durability;Sulfate attack resistance
摘要:
Industrial solid wastes are inducing severe environmental problems, but the problem can be overcame by reusing them as construction materials. The sulfate resistances of sustainable concrete incorporating various solid waste materials, including waste glass powder (WGP), coal gangue powder (CGP) and fly ash (FA) were investigated in this study. Concrete mixes with different water to binder (w/b) ratios and containing various solid waste materials as partial replacement of Portland cement by ratios of 10%, 20%, and 30% were prepared. These mixes were immersed in the 5% Na<inf>2</inf>SO<inf>4</inf> solution for a total period of 22 months. The sulfate attack resistances were evaluated extensively based on visual appearance, mass change, compressive strength, splitting tensile strength, ultrasonic pulse velocity, mineralogy, and microstructure. The results indicate that regardless of the type and content of solid waste materials, the replacement of cement by solid waste materials exhibit a positive impact on the sulfate attack resistance. Under the same substitution level, WGP appear to be the most effective in offsetting the destructive effect of sulfate attack, followed by CGP and FA. Therefore, sustainable concrete incorporating solid waste materials can not only promote the recycling of solid waste, but also provide high sulfate attack resistance.<br/> ©2019 Elsevier Ltd
语种:
英文
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Dynamic responses of high-speed railway transition zone with various subgrade fillings
作者:
Hu, Ping;Zhang, Chunshun* ;Wen, Sen;Wang, Yonghe
期刊:
Computers and Geotechnics ,2019年108:17-26 ISSN:0266-352X
通讯作者:
Zhang, Chunshun
作者机构:
[Hu, Ping] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Zhang, Chunshun; Hu, Ping] Monash Univ, Dept Civil Engn, Melbourne, Vic 3800, Australia.;[Wen, Sen] Henan Univ, Sch Civil Engn & Architecture, Kaifeng 475004, Peoples R China.;[Wang, Yonghe] Cent S Univ, Sch Civil Engn, Changsha 410075, Hunan, Peoples R China.
通讯机构:
[Zhang, Chunshun] M;Monash Univ, Dept Civil Engn, Melbourne, Vic 3800, Australia.
关键词:
Dynamic analysis;High-speed railway;Subgrade fillings;Transition zone
摘要:
In order to explore more economic filling alternatives than typically used graded gravel + 5% cement in a high-speed railway transition zone, engineering properties of graded gravel (without cement) and A, B group filling (well graded coarse-grained soil with less than 30% of fine-grained soil) were tested. This is followed by the establishment of a 3D vertical coupling dynamic model of a tunnel-culvert-tunnel transition section based on the D'Alembert's principle of energy weak variation and the Lagrange scheme. The model results have been validated against the in situ measurements. The analysis from the model show that both graded gravel and A, B group filling are well-graded with high strengths, and the dynamic responses of the roadbed supported by the two fillings are both less than allowable values at the speed of 350 km/h. However, the curves of vertical displacement along the longitudinal transition section are great like a shape of “W” with the A, B group filling in the transition zone. Therefore, the graded gravel is recommended to be more suitable than the A, B group filling for the studied tunnel-culvert-tunnel transition zone. This recommendation may be applicable to the case with a rock subgrade underneath to support the transition zone. Comparatively, for a soil subgrade under the transition zone, our results indicate that graded gravel + 5% cement is still the best filling material, while the other two less stiffer filling materials would result in considerable fluctuations to the roadbed surface. © 2018 Elsevier Ltd
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英文
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Improving Anaerobic Digested Sludge Dewaterability through Gamma-Ray Irradiation and Struvite Precipitation
作者:
Wu, Yuqi;Jiang, Yinghe* ;Ke, Guojun
期刊:
Journal of Environmental Engineering ,2018年144(2):04017101-null ISSN:0733-9372
通讯作者:
Jiang, Yinghe
作者机构:
[Jiang, Yinghe; Wu, Yuqi] Wuhan Univ Technol, Sch Civil Engn & Architecture, Wuhan 430070, Hubei, Peoples R China.;[Wu, Yuqi; Ke, Guojun] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.
通讯机构:
[Jiang, Yinghe] W;Wuhan Univ Technol, Sch Civil Engn & Architecture, Wuhan 430070, Hubei, Peoples R China.
关键词:
Anaerobic digested sludge;Gamma-ray irradiation;Dewaterability;Struvite
摘要:
Anaerobic digestion is a generally used microbial process in wastewater treatment plants, and anaerobic digestion sludge often possesses unacceptable characteristics including high resistance to solid-liquid separation and high concentration of nutrients, such as phosphorus and nitrogen. Gamma-ray irradiation was used to improve the dewaterability of anaerobic digestion sludge, and the struvite (magnesium ammonium phosphate) precipitation method was utilized to recover increased orthophosphate (PO43 - P) and ammonium nitrogen (NH4+-N) from the postirradiation liquor. An absorbed dose of 5-15 kGy would be potentially successful for dewaterability improvement, and the optimal dewaterability occurred at 10 kGy, which could reduce the water content of sludge cake from 80.08 to 73.46%. The mechanism for the enhanced dewaterability was also analyzed, and the lysis of extracelluar polymeric substances and reduction of particle surface charges were found to be the major reasons. Furthermore, the recovery rate of PO43 - P and NH4+-N were 86.07 and 15.08%, respectively, under the condition of Mg/P of 1.8 (molar ratio), pH 9.6, and reaction time of 30 min.<br/> ©2017 American Society of Civil Engineers.
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英文
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Thermal buoyancy driven flows inside the industrial buildings primarily ventilated by the mechanical fans: Local facilitation and infiltration
作者:
Mei, Shuo-Jun;Hu, Jiang-Tao;Liu, Di* ;Zhao, Fu-Yun* ;Wang, Han-Qing
期刊:
Energy and Buildings ,2018年175:87-101 ISSN:0378-7788
通讯作者:
Zhao, Fu-Yun;Liu, Di
作者机构:
[Hu, Jiang-Tao; Zhao, Fu-Yun; Mei, Shuo-Jun] Wuhan Univ, Key Lab Hydraul Machinery Transients, Minist Educ, Wuhan, Hubei, Peoples R China.;[Hu, Jiang-Tao; Zhao, Fu-Yun; Mei, Shuo-Jun] Wuhan Univ, Hubei Key Lab Waterjet Theory & New Technol, Wuhan, Hubei, Peoples R China.;[Hu, Jiang-Tao; Zhao, Fu-Yun; Mei, Shuo-Jun] Wuhan Univ, Sch Power & Mech Engn, Wuhan 430072, Hubei, Peoples R China.;[Liu, Di] China Univ Petr, Coll Pipeline & Civil Engn, Qingdao, Shandong, Peoples R China.;[Wang, Han-Qing] Univ South China, Sch Civil Engn, Hengyang, Hunan, Peoples R China.
通讯机构:
[Zhao, Fu-Yun] W;[Liu, Di] C;Wuhan Univ, Sch Power & Mech Engn, Wuhan 430072, Hubei, Peoples R China.;China Univ Petr, Coll Pipeline & Civil Engn, Qingdao, Shandong, Peoples R China.
关键词:
Local ventilated cooling;Mechanical assisted natural ventilation;Natural ventilation of industrial buildings;On-site measurements
摘要:
The turbine hall houses a number of components with intense heat release, resulting in a hot and humid air environment and making it very unpleasant for plant staffs to conduct maintenance work there, particularly at a hot outdoor environment. The traditional pure buoyancy driven natural ventilated could fulfil the overall heat exhausting requirement, however, creating hot environment at several positions due to the vortex airflow structure. As only part of the building need to be cooled, a localized cooling system with assisting mechanical fans is used. Buoyancy driven natural ventilated flows primarily occupying this turbine hall have been investigated by a computational fluid dynamics (CFD) model and an on-site measurement. The ventilation airflow is solved by 3D steady state Reynolds Averaged Navier-Stokes (RANS) equations in conjunction with the SST k-ω turbulence model. The numerical codes and procedures were validated by comparing with on-site measurements. The concept of mean age of air is used to evaluate the natural ventilated efficacy. Following that, the potential of using mechanical vents and slabs to cool equipment work area at this buoyancy driven natural ventilated hall is analysed. The simulation results show that the mechanical vents could decrease air temperature and increase air exchange efficiency at work area effectively on condition that the local airflow pattern is well organized, which is strongly related to the ejection direction and velocity. Present research could benefit future development of the ventilation design in the power plant buildings. © 2018 Elsevier B.V.
语种:
英文
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Buoyancy driven double diffusive moisture convection inside the fluid-porous-solid sandwiched building enclosure containing internal heating sources
作者:
Hu, Jiang-Tao;Mei, Shuo-Jun;Liu, Di;Zhao, Fu-Yun* ;Wang, Han-Qing
期刊:
International Journal of Heat and Mass Transfer ,2018年123:600-615 ISSN:0017-9310
通讯作者:
Zhao, Fu-Yun
作者机构:
[Hu, Jiang-Tao; Zhao, Fu-Yun; Mei, Shuo-Jun] Wuhan Univ, Minist Educ, Key Lab Hydraul Machinery Transients, Wuhan, Hubei, Peoples R China.;[Hu, Jiang-Tao; Zhao, Fu-Yun; Mei, Shuo-Jun] Wuhan Univ, Hubei Key Lab Waterjet Theory & New Technol, Wuhan, Hubei, Peoples R China.;[Hu, Jiang-Tao; Zhao, Fu-Yun; Mei, Shuo-Jun] Wuhan Univ, Sch Power & Mech Engn, Dong Hu Southern Rd, Wuhan 430072, Hubei, Peoples R China.;[Liu, Di] China Univ Petr, Coll Pipeline & Civil Engn, Qingdao, Shandong, Peoples R China.;[Wang, Han-Qing] Univ South China, Sch Civil Engn, Hengyang, Hunan, Peoples R China.
通讯机构:
[Zhao, Fu-Yun] W;Wuhan Univ, Sch Power & Mech Engn, Dong Hu Southern Rd, Wuhan 430072, Hubei, Peoples R China.
关键词:
Double diffusive convection;Thermal storage composite wall;Thermal conductivity ratio;Internal heat generation
摘要:
Double diffusive convection in an enclosure partially inserted with heat-generated porous layer and solid layer is investigated numerically. Moist air motions are simultaneously driven by the internal heat generation and external concentration difference imposed across the enclosure. Identical porous and solid layers are attached to the vertical walls, and the walls are held at constant temperatures and concentrations. The horizontal walls of the enclosure are assumed to be adiabatic and impermeable. The aspect ratio of the cavity is equal to 1.0 and the saturating fluid is moist air (Pr = 0.7 and Le = 0.8). Present research covers the range of Ra<inf>t</inf>from 10<sup>3</sup>to 10<sup>7</sup>, N from −10.0 to 10.0, Da from 10<sup>−9</sup>to 10<sup>−1</sup>, Φfrom −90°to 90°, and Kr<inf>f</inf>and Kr<inf>s</inf>from 0.1 to 10.0. The results show that the thermal and solutal buoyancy forces are always aiding with each other and the minus sign of N only has influence on the fluid orientations. For the vertical case, heat and moisture transfer of fluid/porous interface is analyzed as a function of the buoyancy ratio. Average Nusselt and Sherwood numbers are increasing functions of Ra<inf>t</inf>, N, Kr<inf>p</inf>and Kr<inf>s</inf>. Furthermore, volume averaged heat transfer rate as functions of inclination angle, for N >0.0, is presented like a sinusoid, where the maximum is near at Ф= 45°and 135°, whereas the minimum is located at Ф= 90°. Present research could benefit future development of sustainable building energy storage.<br/> ©2018 Elsevier Ltd
语种:
英文
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Dynamic responses of bridge–embankment transitions in high speed railway: Field tests and data analyses
作者:
Hu, Ping;Zhang, Chunshun;Chen, Shu Jian;Wang, Yonghe;Wang, Wei;...
期刊:
Engineering Structures ,2018年175:565-576 ISSN:0141-0296
通讯作者:
Duan, Wen Hui
作者机构:
[Hu, Ping] South China Univ, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Wang, Wei; Zhang, Chunshun; Hu, Ping; Duan, Wen Hui; Chen, Shu Jian] Monash Univ, Dept Civil Engn, Melbourne, Vic 3800, Australia.;[Wang, Yonghe] Cent S Univ, Sch Civil Engn, Changsha 410075, Hunan, Peoples R China.
通讯机构:
[Duan, Wen Hui] M;Monash Univ, Dept Civil Engn, Melbourne, Vic 3800, Australia.
关键词:
Ballastless track;Bridge–embankment transition;Data analysis;Dynamic response;High speed railway;Wavelet soft threshold
摘要:
By virtue of its high speed, steadiness, and quality experience, high speed railway (HSR) has grown rapidly. During that development, problems such as dynamic irregularity in the bridge–embankment transition have been exposed and have aroused keen attention. To study dynamic performance in bridge–embankment transition, field dynamic tests under 120 high speed vehicles running at speeds of 5–360 km/h were carried out. Then, processed signals were obtained from the original signals by a series of signal processing methods such as wavelet soft threshold filtering, Newton-Cortege integration, and five-thirds smoothing. Moreover, the statistical test data were analyzed in the time/frequency domain to obtain the frequency characteristics, the rules governing changes in dynamic responses along the longitudinal and depth directions, and the rules governing changes in dynamic responses with train speed, train running direction, vehicle axle load, and adjacent load. The results showed that (i) the concentration range of the first two main frequency was generally 0–50 Hz, (ii) particular attention should be paid to sections 7.5 m, 13 m and 25 m from the abutment tail, and (iii) importance should be attached to the bed surface layer. As well, 275 km/h was the critical train speed and acceleration was a sensitive dynamic index. Finally, the dynamic responses showed that a bridge–embankment transition with the subgrade filled with graded gravel + 5% cement satisfied design and operation requirements at speeds of 5–360 km/h. © 2018
语种:
英文
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Simultaneous determination of the radon diffusion coefficient and the free radon production rate from compact porous emanation media
作者:
Ye, Yong-jun* ;Wu, Wen-hao;Feng, Sheng-yang;Huang, Chun-huang;Li, Shi
期刊:
Building and Environment ,2018年144:66-71 ISSN:0360-1323
通讯作者:
Ye, Yong-jun
作者机构:
[Li, Shi; Ye, Yong-jun; Wu, Wen-hao; Feng, Sheng-yang] Univ South China, Sch Environm & Safety Engn, Hengyang 421001, Hunan, Peoples R China.;[Huang, Chun-huang] Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.;[Ye, Yong-jun] Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium Mi, Hengyang 421001, Hunan, Peoples R China.
通讯机构:
[Ye, Yong-jun] U;Univ South China, Sch Environm & Safety Engn, Hengyang 421001, Hunan, Peoples R China.
关键词:
Compact porous emanation media;Diffusion coefficient;Production rate;Radon
摘要:
The radon diffusion coefficient and the free radon production rate are important parameters for used to describe the migration of radon in porous emanation media. However, the method currently used to determine these two parameters is complicated. Based on a theory of the radon exhalation by diffusion from the inner and outer surfaces of a circular tube, a method to determine these two parameters in compact porous emanation media was proposed, and an experimental measuring device was designed and manufactured. The experimental device was used to simultaneously measure the radon exhalation rate from the inner and outer surfaces of a quarter-circular tubular concrete block filled with fine-grained uranium tailing sand. The measurements were used to calculate the radon diffusion coefficient and the free radon production rate. The result obtained by using this method shows that accuracy was within the accepted range of experimental error. This method has practical value for the simultaneous determination of the radon diffusion coefficient and the free radon production rate from compact porous emanation media. © 2018
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英文
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