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Effect of loading rate on shear strength parameters of mechanically and biologically treated waste

《环境科学与工程前沿（英文）》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1595-7

摘要：

● Mechanical behavior of MBT waste affected by loading rate was investigated.

关键词： Mechanically and biologically treated waste     Landfill     Triaxial test     Loading rate     Axial strain     Shear strength parameter    

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Reconsideration on the effect of nitrogen on mixed culture polyhydroxyalkanoate production toward high organic loading

Zhiqiang Chen, Lizhi Zhao, Ye Ji, Qinxue Wen, Long Huang

《环境科学与工程前沿（英文）》 2019年 第13卷 第4期 doi: 10.1007/s11783-019-1135-2

摘要：

Effect of nitrogen on mixed culture PHA production was reconsidered.

Enrichment history of PHA accumulating culture was discussed.

Higher PHA content and biomass growth were achieved in presence of nitrogen.

Enrichment strategy toward higher PHA accumulation was investigated.

Microbial community succession in PHA accumulation phase was investigated.

关键词： Polyhydroxyalkanoate (PHA)     Organic loading rate     Nitrogen content     Biomass growth     Enrichment history    

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Microbial community dynamics at high organic loading rates revealed by pyrosequencing during sugar refinery

Liguo Zhang, Qiaoying Ban, Jianzheng Li

《环境科学与工程前沿（英文）》 2018年 第12卷 第4期 doi: 10.1007/s11783-018-1045-8

摘要：

High strength sugar refinery wastewater was treated in a mesophilic UASB.

Pyrosequencing reveals microbial community succession with OLR increase.

Diversity of microbial communities in OLR12 is much higher than those in OLR36 and OLR54.0 kgCOD/(kg VSS·d).

Fermentative bacteria could deal with increasing OLR through the increase of microbial diversity and quantity.

Hydrogen-producing acotogens and methanogens mainly coped with high OLR shocks by increasing the quantity of community

关键词： Upflow anaerobic sludge blanket     Sugar refinery wastewater     Organic loading rate     Pyrosequencing     Microbial community structure    

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Start-up of PN-anammox system under low inoculation quantity and its restoration after low-loading rate

Guoliang Zhang, Liang Zhang, Xiaoyu Han, Shujun Zhang, Yongzhen Peng

《环境科学与工程前沿（英文）》 2021年 第15卷 第2期 doi: 10.1007/s11783-020-1324-z

摘要： Abstract • PN-A was start-up under low inoculation amount and a higher NRR was achieved. • PN-anammox system was successfully restored by aggressive sludge discharge. • Increase in granular sludge was the important factor to rapid recovery. • Enrichment of AOB and AnAOB in granular sludge favors the stable operation. Partial nitritation (PN)-anaerobic ammonium oxidation (anammox) is a promising pathway for the biological treatment of wastewater. However, the destruction of the system caused by excessive accumulation of nitrate in long-term operation remains a challenge. In this study, PN-anammox was initialized with low inoculation quantity in an air-lift reactor. The nitrogen removal rate of 0.71 kgN/(m3·d) was obtained, which was far higher than the seed sludge (0.3 kgN/(m3·d)). Thereafter, excess nitrate build-up was observed under low-loading conditions, and recovery strategies for the PN-anammox system were investigated. Experimental results suggest that increasing the nitrogen loading rate as well as the concentration of free ammonium failed to effectively suppress the nitrite oxidation bacteria (NOB) after the PN-anammox system was disrupted. Afterwards, effluent back-flow was added into the reactor to control the up-flow velocity. As a result, an aggressive discharge of sludge that promoted the synergetic growth of functional bacteria was achieved, leading to the successful restoration of the PN-anammox system. The partial nitritation and anammox activity were in balance, and an increase in nitrogen removal rate up to 1.07 kgN/(m3·d) was obtained with a nitrogen removal efficiency of 82.4% after recovery. Besides, the proportion of granular sludge (over 200 mm) increased from 33.67% to 82.82%. Ammonium oxidation bacteria (AOB) along with anammox bacteria were enriched in the granular sludge during the recovery period, which was crucial for the recovery and stable operation of the PN-anammox system.

关键词： PN-anammox     Granular sludge     Excess nitrate build-up     Recovery strategy for partial nitrification     Aggressive discharge of sludge    

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Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration

Jun WU,Xuemei LIU

《结构与土木工程前沿（英文）》 2015年 第9卷 第3期   页码 323-340 doi: 10.1007/s11709-015-0301-2

摘要： This paper presents a combined experimental and numerical study on the damage and performance of a soft-hard-soft (SHS) multi-layer cement based composite subjected to blast loading which can be used for protective structures and infrastructures to resist extreme loadings, and the composite consists of three layers of construction materials including asphalt concrete (AC) on the top, high strength concrete (HSC) in the middle, and engineered cementitious composites (ECC) at the bottom. To better characterize the material properties under dynamic loading, interface properties of the composite were investigated through direct shear test and also used to validate the interface model. Strain rate effects of the asphalt concrete were also studied and both compressive and tensile dynamic increase factor (DIF) curves were improved based on split Hopkinson pressure bar (SHPB) test. A full-scale field blast test investigated the blast behavior of the composite materials. The numerical model was established by taking into account the strain rate effect of all concrete materials. Furthermore, the interface properties were also considered into the model. The numerical simulation using nonlinear finite element software LS-DYNA agrees closely with the experimental data. Both the numerical and field blast test indicated that the SHS composite exhibited high resistance against blast loading.

关键词： high strength concrete (SHS)     engineered cementitious composite     interface     blast test     strain rate effect    

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Shear-critical reinforced concrete columns under various loading rates

Witarto WITARTO,Liang LU,Rachel Howser ROBERTS,Y. L. MO,Xilin LU

《结构与土木工程前沿（英文）》 2014年 第8卷 第4期   页码 362-372 doi: 10.1007/s11709-014-0083-y

摘要： This paper presents an experimental study of shear-governed reinforced concrete columns subjected to different loading rates. Four typical short columns were tested cyclically with loading rate of 0.05, 1, 3, and 5 Hz, simulating seismic load. Test result indicated that the loading rate does not affect the column behavior when the rate is up to 5 Hz. Furthermore, Carbon Nano-Fiber Aggregates (CNFAs) were utilized as internal sensors to detect the damage in the column. The test result shows that the CNFAs work well sensing the structural behavior. The CNFA output was further quantitatively correlated to the structural damage level. Finally, a finite element analytical model was constructed to describe the behavior of short columns with shear failure. The analytical model successfully modeled the cyclic loading test results.

关键词： reinforced concrete columns     shear failure     loading rate     Carbon Nano-Fiber Aggregates (CNFAs)     finite element analysis     OpenSees    

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Continuous biohydrogen production from diluted molasses in an anaerobic contact reactor

Sheng CHANG, Jianzheng LI, Feng LIU

《环境科学与工程前沿（英文）》 2011年 第5卷 第1期   页码 140-148 doi: 10.1007/s11783-010-0258-2

摘要： An anaerobic contact reactor (ACR) system comprising a continuous flow stirred tank reactor (CSTR) with settler to decouple the hydraulic retention time (HRT) from solids retention time (SRT) was developed for fermentative hydrogen production from diluted molasses by mixed microbial cultures. The ACR was operated at various volumetric loading rates (VLRs) of 20–44 kgCOD·m ·d with constant HRT of 6 h under mesophilic conditions of 35°C. The SRT was maintained at about 46–50 h in the system. At the initial VLR of 20 kgCOD·m ·d , the hydrogen production rate dropped from 22.6 to 1.58 L·d as the hydrogen was consumed by the hydrogentrophic methanogen. After increasing the VLR to 28 kgCOD·m ·d and discharging the sludge for 6 consecutive times, the hydrogentrophic methanogens were eliminated, and the hydrogen content reached 36.4%. As the VLR was increased to 44 kgCOD·m ·d , the hydrogen production rate and hydrogen yield increased to 42.1 L·d and 1.40 mol H ·molglucose-consumed , respectively. The results showed that a stable ethanol-type fermentation that favored hydrogen production in the reactor was thus established with the sludge loading rate (SLR) of 2.0–2.5 kgCOD·kgMLVSS ·d . It was found that the ethanol increased more than other liquid fermentation products, and the ethanol/acetic acid (mol/mol) ratio increased from 1.27 to 2.45 when the VLR increased from 28 to 44 kgCOD·m ·d , whereas the hydrogen composition decreased from 40.4% to 36.4%. The results suggested that the anaerobic contact reactor was a promising bioprocess for fermentative hydrogen production.

关键词： fermentative hydrogen production     anaerobic contact reactor (ACR)     sludge loading rate (SLR)     butyric acid-type fermentation     ethanol-type fermentation    

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enhanced damage plasticity model for predicting the cyclic behavior of plain concrete under multiaxial loading

Mohammad Reza AZADI KAKAVAND, Ertugrul TACIROGLU

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1531-1544 doi: 10.1007/s11709-020-0675-7

摘要： Some of the current concrete damage plasticity models in the literature employ a single damage variable for both the tension and compression regimes, while a few more advanced models employ two damage variables. Models with a single variable have an inherent difficulty in accounting for the damage accrued due to tensile and compressive actions in appropriately different manners, and their mutual dependencies. In the current models that adopt two damage variables, the independence of these damage variables during cyclic loading results in the failure to capture the effects of tensile damage on the compressive behavior of concrete and vice-versa. This study presents a cyclic model established by extending an existing monotonic constitutive model. The model describes the cyclic behavior of concrete under multiaxial loading conditions and considers the influence of tensile/compressive damage on the compressive/tensile response. The proposed model, dubbed the enhanced concrete damage plasticity model (ECDPM), is an extension of an existing model that combines the theories of classical plasticity and continuum damage mechanics. Unlike most prior studies on models in the same category, the performance of the proposed ECDPM is evaluated using experimental data on concrete specimens at the material level obtained under cyclic multiaxial loading conditions including uniaxial tension and confined compression. The performance of the model is observed to be satisfactory. Furthermore, the superiority of ECDPM over three previously proposed constitutive models is demonstrated through comparisons with the results of a uniaxial tension-compression test and a virtual test.

关键词： damage plasticity model     plain concrete     cyclic loading     multiaxial loading conditions    

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Anaerobic treatment of fresh leachate from a municipal solid waste incinerator by upflow blanket filter reactor

Pinjing HE, Min LI, Suyun XU, Liming SHAO,

《环境科学与工程前沿（英文）》 2009年 第3卷 第4期   页码 404-411 doi: 10.1007/s11783-009-0149-6

摘要： This paper describes the feasibility of fresh leachate treatment by an upflow blanket filter (UBF). Through dilution and partial effluent recycling, the organic loading rates increased from 0.51to 14.56kg COD/(m·d), meanwhile the corresponding hydraulic retention time decreased from 9.0d to 3.6d. The reactor was able to achieve steady-state within 80d. Based on the distribution of COD fluxes in the process, it was concluded that anabolism was the main pathway of COD removal in the initial phase (1―33d), accounting for 57%―85% of total COD removed. As the anaerobic consortium of bacteria reached steady-state (after 70―86d), the majority of COD removed was transformed into methane, because the specific methane yield was close to the theoretical value (0.36L CH/(g COD)).

关键词： distribution of COD fluxes     effluent recycling     leachate     methane yield     organic loading rate     upflow blanket filter    

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Axisymmetric loading on nanoscale multilayered media

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 152-164 doi: 10.1007/s11709-022-0895-0

摘要： Multilayered nanoscale structures are used in several applications. Because the effect of surface energy becomes nontrivial at such a small scale, a modified continuum theory is required to accurately predict their mechanical behaviors. A Gurtin–Murdoch continuum model of surface elasticity is implemented to establish a computational scheme for investigating an elastic multilayered system under axisymmetric loads with the incorporation of surface/interface energy. Each layer stiffness matrix is derived based on the general solutions of stresses and displacements obtained in the form of the Hankel integral transform. Numerical solutions to the global equation, which are formulated based on the continuity conditions of tractions and displacements across interfaces between layers, yield the displacements at each layer interface and on the top surface of the multilayered medium. The numerical solutions indicate that the elastic responses of multilayered structures are affected significantly by the surface material properties of both the top surface and interfaces, and that they become size dependent. In addition, the indentation problem of a multilayered nanoscale elastic medium under a rigid frictionless cylindrical punch is investigated to demonstrate the application of the proposed solution scheme.

关键词： functionally graded layer     Gurtin–Murdoch surface elasticity     multilayered medium     size dependency     stiffness matrix    

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Data-driven approach to solve vertical drain under time-dependent loading

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 696-711 doi: 10.1007/s11709-021-0727-7

摘要： Currently, the vertical drain consolidation problem is solved by numerous analytical solutions, such as time-dependent solutions and linear or parabolic radial drainage in the smear zone, and no artificial intelligence (AI) approach has been applied. Thus, in this study, a new hybrid model based on deep neural networks (DNNs), particle swarm optimization (PSO), and genetic algorithms (GAs) is proposed to solve this problem. The DNN can effectively simulate any sophisticated equation, and the PSO and GA can optimize the selected DNN and improve the performance of the prediction model. In the present study, analytical solutions to vertical drains in the literature are incorporated into the DNN–PSO and DNN–GA prediction models with three different radial drainage patterns in the smear zone under time-dependent loading. The verification performed with analytical solutions and measurements from three full-scale embankment tests revealed promising applications of the proposed approach.

关键词： vertical drain     artificial neural network     time-dependent loading     deep learning network     genetic algorithm     particle swarm optimization    

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Comparison and harmonization of building wind loading codes among the Asia-Pacific Economies

Yaojun GE, Shuyang CAO, Xinyang JIN

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 402-410 doi: 10.1007/s11709-013-0230-x

摘要： This paper reviews wind loading codes and standards in the Asia-Pacific Region, in particular in the 15 countries and areas. A general description of wind loading model is given as a famous wind loading chain described by four variables including velocity pressure, exposure factor, pressure coefficient, and gust response factor. Through the APEC-WW Workshops and the extensive calculations for three examples of low, medium and high rise buildings, these four important variables of wind loads are evaluated and compared with statistical parameters, mean values and coefficients of variation. The main results of the comparison show some differences among the 15 economies, and the reasons and further incorporation are discussed and suggested.

关键词： wind loading     codification     velocity pressure     exposure factor     pressure coefficient     gust response factor    

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Solution to economic dispatch problem with valve-point loading effect by using catfish PSO algorithm

K. MURALI,T. JAYABARATHI

《能源前沿（英文）》 2014年 第8卷 第3期   页码 290-296 doi: 10.1007/s11708-014-0305-y

摘要： This paper proposes application of a catfish particle swarm optimization (PSO) algorithm to economic dispatch (ED) problems. The ED problems considered in this paper include valve-point loading effect, power balance constraints, and generator limits. The conventional PSO and catfish PSO algorithms are applied to three different test systems and the solutions obtained are compared with each other and with those reported in literature. The comparison of solutions shows that catfish PSO outperforms the conventional PSO and other methods in terms of solution quality though there is a slight increase in computational time.

关键词： economic dispatch (ED)     valve point loading     catfish particle swarm optimization (PSO)     optimization    

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Effect of Fe loading quantity on reduction reactivity of nano zero-valent iron supported on chelating

Jialu SHI,Shengnan YI,Chao LONG,Aimin LI

《环境科学与工程前沿（英文）》 2015年 第9卷 第5期   页码 840-849 doi: 10.1007/s11783-015-0781-2

摘要： In this study, nanoscale zero-valent iron (NZVI) were immobilized within a chelating resin (DOW 3N). To investigate the effect of Fe loading on NZVI reactivity, three NZVI-resin composites with different Fe loading were obtained by preparing Fe(III) solution in 0, 30 and 70% (v/v) ethanol aqueous, respectively; the bromate was used as a model contaminant. TEM reveals that increasing the Fe loading resulted in much larger size and poor dispersion of nanoscale iron particles. The results indicated that the removal efficiency of bromate and the rate constant ( ) were decreased with increasing the Fe loading. For the NZVI-resin composite with lower Fe loading, the removal efficiency of bromate declined more significantly with the increase of DO concentrations. Under acidic conditions, decreasing the pH value had the most significant influence on NZVI-R3 with highest Fe loading for bromate removal; however, under alkaline conditions, the most significant influence of pH was on NZVI-R1 with lowest Fe loading. The effects of co-existing anions , and were also investigated. All of the co-existing anions showed the inhibition to bromate reduction.

关键词： nanoscale zero valent iron     loading quantity     reduction     chelating resin     bromated    

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The combined effects of biomass and temperature on maximum specific ammonia oxidation rate in domestic

《环境科学与工程前沿（英文）》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1411-9

摘要：

• Actual SAORs was determined using MLVSS and temperature.

关键词： Specific ammonia oxidation rate     Sequencing batch reactor     Biomass     Temperature coefficient     Model simulation    

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标题 作者 时间 类型 操作

Effect of loading rate on shear strength parameters of mechanically and biologically treated waste

期刊论文

Reconsideration on the effect of nitrogen on mixed culture polyhydroxyalkanoate production toward high organic loading

Zhiqiang Chen, Lizhi Zhao, Ye Ji, Qinxue Wen, Long Huang

期刊论文

Microbial community dynamics at high organic loading rates revealed by pyrosequencing during sugar refinery

Liguo Zhang, Qiaoying Ban, Jianzheng Li

期刊论文

Start-up of PN-anammox system under low inoculation quantity and its restoration after low-loading rate

Guoliang Zhang, Liang Zhang, Xiaoyu Han, Shujun Zhang, Yongzhen Peng

期刊论文

Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration

Jun WU,Xuemei LIU

期刊论文

Shear-critical reinforced concrete columns under various loading rates

Witarto WITARTO,Liang LU,Rachel Howser ROBERTS,Y. L. MO,Xilin LU

期刊论文

Continuous biohydrogen production from diluted molasses in an anaerobic contact reactor

Sheng CHANG, Jianzheng LI, Feng LIU

期刊论文

enhanced damage plasticity model for predicting the cyclic behavior of plain concrete under multiaxial loading

Mohammad Reza AZADI KAKAVAND, Ertugrul TACIROGLU

期刊论文

Anaerobic treatment of fresh leachate from a municipal solid waste incinerator by upflow blanket filter reactor

Pinjing HE, Min LI, Suyun XU, Liming SHAO,

期刊论文

Axisymmetric loading on nanoscale multilayered media

期刊论文

Data-driven approach to solve vertical drain under time-dependent loading

期刊论文

Comparison and harmonization of building wind loading codes among the Asia-Pacific Economies

Yaojun GE, Shuyang CAO, Xinyang JIN

期刊论文

Solution to economic dispatch problem with valve-point loading effect by using catfish PSO algorithm

K. MURALI,T. JAYABARATHI

期刊论文

Effect of Fe loading quantity on reduction reactivity of nano zero-valent iron supported on chelating

Jialu SHI,Shengnan YI,Chao LONG,Aimin LI

期刊论文

The combined effects of biomass and temperature on maximum specific ammonia oxidation rate in domestic

期刊论文