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Plasma-assisted oxidation of benzoic acid

Anna Khlyustova, Nikolay Sirotkin

《化学科学与工程前沿（英文）》 2020年 第14卷 第4期   页码 513-521 doi: 10.1007/s11705-019-1825-0

摘要： Plasma-assisted oxidation of organic compounds is one of the developing technologies for wastewater treatment. Plasmas effectively accelerate degradation processes due to plasma generated reactive species and ultra-violet radiation. Oxidation of benzoic acid in aqueous solutions by the atmospheric pressure glow discharge and underwater diaphragm discharge was studied and monitored by fluorescence and spectrophotometric methods. Discharge type and solution pH affect the formation rates of mono- and dihydroxybenzoic acids. Dihydroxyl derivatives were formed only by glow discharge action. The yields of hydroxyl radical were estimated on the kinetics data for the hydroxylation of benzoic acid. The steps of the hydroxylation processes and further oxidation were described.

关键词： atmospheric pressure glow discharge     underwater diaphragm discharge     oxidation     benzoic acid     hydroxyl radical    

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Finite element modeling of thermo-active diaphragm walls

Yi RUI, Mei YIN

《结构与土木工程前沿（英文）》 2020年 第14卷 第3期   页码 646-663 doi: 10.1007/s11709-020-0584-9

摘要： There are two major challenges faced by modern society: energy security, and lowering carbon dioxide gas emissions. Thermo-active diaphragm walls have a large potential to remedy one of these problems, since they are a renewable energy technology that uses underground infrastructure as a heat exchange medium. However, extensive research is required to determine the effects of cyclic heating and cooling on their geotechnical and structural performance. In this paper, a series of detailed finite element analyses are carried out to capture the fully coupled thermo-hydro-mechanical response of the ground and diaphragm wall. It is demonstrated that the thermal operation of the diaphragm wall causes changes in soil temperature, thermal expansion/shrinkage of pore water, and total stress applied on the diaphragm wall. These, in turn, cause displacements of the diaphragm wall and variations of the bending moments. However, these effects on the performance of diaphragm wall are not significant. The thermally induced bending strain is mainly governed by the temperature differential and uneven thermal expansion/shrinkage across the wall.

关键词： thermo-active diaphragm wall     finite element analysis     thermo-hydro-mechanical coupling     ground source heat pump    

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Parametric sensitivity analysis of cellular diaphragm wall

Xi CHEN, Wei XU

《结构与土木工程前沿（英文）》 2012年 第6卷 第4期   页码 358-364 doi: 10.1007/s11709-012-0177-3

摘要： The deformation law of the cellular diaphragm wall in deep foundation pits was studied through numerical simulation. Based on the example of the dock wall in engineering, the full three-dimensional finite element model was used to simulate the excavation of the foundation pit. Interaction between the cellular diaphragm wall and the soil was also taken into account in the calculation. The results indicated that the maximum lateral displacement, which is the evaluation index of sensitivity analysis, appeared on the top of the interior longitudinal wall with an excavation depth of 10 m. The centrifuge model test was carried out to study the deformation regulation for a cellular diaphragm wall. The most sensitive factor was found by adjusting the length of the partition wall, the spacing of the partition wall and the thickness of the wall. In the end, a suggestion was proposed to optimize the cellular diaphragm by adjusting the length of the partition wall.

关键词： cellular diaphragm wall     sensitivity analysis     optimization     centrifuge model test    

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Diaphragm wall-soil-cap interaction in rectangular-closed- diaphragm-wall bridge foundations

Hua WEN, Qiangong CHENG, Fanchao MENG, Xiaodong CHEN

《结构与土木工程前沿（英文）》 2009年 第3卷 第1期   页码 93-100 doi: 10.1007/s11709-009-0015-4

摘要： Rectangular-closed-diaphragm-wall foundation is a new type of bridge foundation. Diaphragm wall-soil-cap interaction was studied using a model test. It was observed that the distribution of soil resistance under the cap is not homogeneous. The soil resistance in the corner under the cap is larger than that in the border; and that in the center is the smallest. The distribution of soil resistance under the cap will be more uniform, if the sectional area of soil core is enlarged within a certain range. Due to the existence of cap, there is a “weakening effect” in inner shaft resistance of the upper wall segments, and there is “enhancement effect” in the lower wall segments and in toe resistance. The load shearing percentage of soil resistance under the cap is 10%-20%. It is unreasonable to ignore the effects of the cap and the soil resistance under the cap in bearing capacity calculations.

关键词： diaphragm wall     bridge foundation     low cap     interaction    

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Power performance of circular piezoelectric diaphragm generators

TANG Kehong, KAN Junwu, YANG Zhigang, CHENG Guangming, PENG Taijiang

《机械工程前沿（英文）》 2008年 第3卷 第4期   页码 434-440 doi: 10.1007/s11465-008-0069-3

摘要： Energy generation performance of a piezoelectric generator depends mainly on several elements such as the structural style, boundary conditions, geometry parameters, materials, vibration-source frequency, and external load. To obtain the optimal energy-harvesting device, the Raleigh method is used to establish the analysis model of circular piezoelectric composite diaphragms. Simply supported and clamped boundary conditions were considered. The relationships between the output power and the structural parameters of piezoelectric composite diaphragms, and the external load resistance and frequency were shown. Given the correlative material parameters and boundary conditions, the output power, using structural parameters, external load, or vibrating frequency as variables, can be calculated. Simulation results show that there are optimal structural parameters and load for a composite diaphragm to achieve the maximum output power. A piezoelectric diaphragm generator with given dimensions tends to achieve higher output power under clamped boundary conditions than that under simply supported boundary conditions.

关键词： clamped boundary     energy-harvesting     composite diaphragm     piezoelectric composite     maximum    

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behavior of stiffened joints between concrete-filled steel tubular column and steel beam with narrow outer diaphragm

Chunyan QUAN,Wei WANG,Jian ZHOU,Rong WANG

《结构与土木工程前沿（英文）》 2016年 第10卷 第3期   页码 333-344 doi: 10.1007/s11709-016-0357-7

摘要： This paper presented an investigation on a stiffened joint in practical engineering which was between concrete-filled steel tubular column and steel beam with narrow outer diaphragm and partial joint penetration welds. Through the low-frequency cyclic loading test, the cyclic behavior and failure mode of the specimen were investigated. The results of the test indicated the failure mode and bearing capacity of the specimen which were influenced by the axial compression ratio of the concrete-filled tubular column. On the contrary, the inner diaphragm and inner stiffeners had limited impacts on the hysteretic behavior of the joint. There was no hysteresis damage fracture on the narrow outer diaphragm connected to the concrete-filled steel tubular column with partial joint penetration welds. Due to the excellent ductility and energy dissipating capacity, the proposed joint could be applied to the seismic design of high-rise buildings in highly intensive seismic region, but axial compression ratio should be controlled to avoid unfavorable failure modes.

关键词： narrow outer diaphragm     concrete-filled tubular column     joint     inner and outer stiffening     cyclic behavior    

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Turbidity-adaptive underwater image enhancement method using image fusion

《机械工程前沿（英文）》 2022年 第17卷 第3期 doi: 10.1007/s11465-021-0669-8

摘要： Clear, correct imaging is a prerequisite for underwater operations. In real freshwater environment including rivers and lakes, the water bodies are usually turbid and dynamic, which brings extra troubles to quality of imaging due to color deviation and suspended particulate. Most of the existing underwater imaging methods focus on relatively clear underwater environment, it is uncertain that if those methods can work well in turbid and dynamic underwater environments. In this paper, we propose a turbidity-adaptive underwater image enhancement method. To deal with attenuation and scattering of varying degree, the turbidity is detected by the histogram of images. Based on the detection result, different image enhancement strategies are designed to deal with the problem of color deviation and blurring. The proposed method is verified by an underwater image dataset captured in real underwater environment. The result is evaluated by image metrics including structure similarity index measure, underwater color image quality evaluation metric, and speeded-up robust features. Test results exhibit that the method can correct the color deviation and improve the quality of underwater images.

关键词： turbidity     underwater image enhancement     image fusion     underwater robots     visibility    

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The behavior of a rectangular closed diaphragm wall when used as a bridge foundation

Qiangong CHENG, Jiujiang WU, Zhang SONG, Hua WEN

《结构与土木工程前沿（英文）》 2012年 第6卷 第4期   页码 398-420 doi: 10.1007/s11709-012-0175-5

摘要： The rectangular closed diaphragm (RCD) wall is a new type of bridge foundation. Compared to barrette foundation, measuring the performance of RCD walls is relatively complicated because of their incorporation of a soil core. Using the FLAC3D software, this paper investigates the deformation properties, soil resistance and skin friction of a laterally loaded RCD wall as well as the settlement, axial force and load-sharing ratio of a vertically loaded RCD wall. Special attention is given to the analysis of factors that influence the performance of the soil core. It was found that under lateral loading, the RCD wall behaves as an end-bearing friction wall during the entire loading process. The relative displacement between the wall body and the soil core primarily occurs below the rotation point, and the horizontal displacement of the soil core is greater than that of the wall body. Under vertical loading, the degree of inner skin friction around the bottom of the soil core and the proportion of the loading supported by the soil core increase with increased cross-section size. The wall depth is directly proportional to the loading supported by the outer skin friction and the tip resistance of the wall body and is inversely proportional to the loading borne by the soil core.

关键词： diaphragm wall     soil core     bridge foundation     FLAC3D     bearing behavior    

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Soil arching effect of Lattice-Shaped Diaphragm Wall as bridge foundation

Jiujiang WU, Lingjuan WANG, Qiangong CHENG

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 446-454 doi: 10.1007/s11709-017-0397-7

摘要： As a new type of bridge foundation, Lattice-Shaped Diaphragm Wall (hereinafter for LSDW) is highly concerned in relevant construction area but its research is far from achievement. Based on PFC , the soil arching effect of LSDWs is studied thoroughly in this paper and the special attention is given to its influencing factors. It turns out to be that a differential wall-soil settlement can be found at the lower location of soil core of an LSDW which is one of the trigger factors of soil arching; meanwhile, the differential settlement degree can reflect the exertion degree of soil arching; the shape of soil arching is basically a hemisphere which can be explained by the theory proposed by Hewlett and Randolph; normally, the chamber number is a negative factor for the development of soil arching; the soil arching effect is significantly influenced by the distance of two adjacent wall elements and the foundation depth, and a relatively large or small value of these factors is disadvantageous to the exertion of soil arching; in addition, the soil arching effect increase with the growth of stiffness and friction coefficient of particles and the friction coefficient of particles has insignificant influence on the development of soil arching effect compared with particle stiffness.

关键词： LSDW     soil arching     PFC2D     shape of soil arching     influencing factors    

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水下交通隧道的设计与施工

王梦恕

《中国工程科学》 2009年 第11卷 第7期   页码 4-10

摘要：

综合论述了水下隧道在穿越江河湖海时所有的优势，介绍了水下交通隧道的设计与施工概况，讨论了水下隧道勘察设计、施工的几项关键技术，详细介绍了水下隧道施工的常用方法。

关键词： 水下隧道     设计     施工    

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Centrifuge experiment and numerical analysis of an air-backed plate subjected to underwater shock loading

Zhijie HUANG, Xiaodan REN, Zuyu CHEN, Daosheng LING

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1350-1362 doi: 10.1007/s11709-019-0559-x

摘要： In this study, systematic centrifuge experiments and numerical studies are conducted to investigate the effect of shock loads due to an underwater explosion on the dynamic responses of an air-backed steel plate. Numerical simulations with three different models of pressure time history generated by underwater explosion were carried out. The first model of pressure time history was measured in test. The second model to predict the time history of shock wave pressure from an underwater explosion was created by Cole in 1948. Coefficients of Cole’s formulas are determined experimentally. The third model was developed by Zamyshlyaev and Yakovlev in 1973. All of them are implemented into the numerical model to calculate the shock responses of the plate. Simulated peak strains obtained from the three models are compared with the experimental results, yielding average relative differences of 21.39%, 45.73%, and 13.92%, respectively. The Russell error technique is used to quantitatively analyze the correlation between the numerical and experimental results. Quantitative analysis shows that the simulated strains for most measurement points on the steel plate are acceptable. By changing the scaled distances, different shock impulses were obtained and exerted on the steel plate. Systematic numerical studies are performed to investigate the effect of the accumulated shock impulse on the peak strains. The numerical and experimental results suggest that the peak strains are strongly dependent on the accumulated shock impulse.

关键词： underwater explosion     centrifuge experiment     shock load     dynamic response     accumulated shock impulse    

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Effects of thermocline on performance of underwater glider’s power system propelled by ocean thermal

Hai YANG, Jie MA,

《能源前沿（英文）》 2009年 第3卷 第4期   页码 472-479 doi: 10.1007/s11708-009-0052-7

摘要： The thermal glider’s changeable volume produces propelling force to power the glider’s descending and ascending through the thermocline. The different depth, thickness, and intensity of the thermocline at different seasons and locations affect the working processes of the glider’s power system. Based on the enthalpy method, a mathematical model of the underwater glider’s power system was established and the time efficiency of operation was introduced, so that the effects of different thermoclines on the underwater glider’s power system were analyzed theoretically. The simulation result shows that the thermocline affects the transition time of the phase change processes of working fluids within the thermal engine tubes. There exist the threshold values of the thermocline’s depth and upper thickness for the power system’s operation. A depth or upper thickness of the thermocline less than the corresponding threshold leads the power system to work abnormally. To keep the power system working efficiently, a glider must be kept in warm surface water for a certain period before it moves through cold water, so that the time efficiency of operation is reduced. A less time efficiency of operation is unfavorable to the thermal glider to penetrate through the ocean currents.

关键词： mathematical     underwater glider     system working     certain     corresponding threshold    

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Detecting large-scale underwater cracks based on remote operated vehicle and graph convolutional neural

Wenxuan CAO; Junjie LI

《结构与土木工程前沿（英文）》 2022年 第16卷 第11期   页码 1378-1396 doi: 10.1007/s11709-022-0855-8

摘要： It is of great significance to quickly detect underwater cracks as they can seriously threaten the safety of underwater structures. Research to date has mainly focused on the detection of above-water-level cracks and hasn’t considered the large scale cracks. In this paper, a large-scale underwater crack examination method is proposed based on image stitching and segmentation. In addition, a purpose of this paper is to design a new convolution method to segment underwater images. An improved As-Projective-As-Possible (APAP) algorithm was designed to extract and stitch keyframes from videos. The graph convolutional neural network (GCN) was used to segment the stitched image. The GCN’s m-IOU is 24.02% higher than Fully convolutional networks (FCN), proving that GCN has great potential of application in image segmentation and underwater image processing. The result shows that the improved APAP algorithm and GCN can adapt to complex underwater environments and perform well in different study areas.

关键词： underwater cracks     remote operated vehicle     image stitching     image segmentation     graph convolutional neural network    

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Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

《机械工程前沿（英文）》 2010年 第5卷 第1期   页码 98-105 doi: 10.1007/s11465-009-0088-8

摘要： To study the requirements of the power supply in micro-arc oxidation (MAO) of magnesium alloy, many experiments were performed under the DC, unipolar, and ambipolar pulse output modes. Based on the experimental results and electric arc theory, the separate local arc discharge mechanism was put forward. It is considered that magnesium MAO process consists of three stages including anodic oxidation, micro-arc oxidation, and large-arc discharge in turn with increasing source voltage. The MAO film is composed of metal oxides that resulted from numerous discrete local arc discharges, which accumulate the non-equilibrium structure after undergoing sudden heating and cooling cycles. Separate local arc discharge is caused by the process in which the oxygen-based gas is ionized in the conduct channel bearing electric field intensity, changed from insulator to conductor that presents sharp negative resistance effect, and produced partially high temperature to ignite locally metal oxidation. The local arc discharge model is described as four courses: gas created from electrolysis, arc discharge, metals oxidization, and cooling and shrinking of oxides. The purpose of pulse supply is to inhibit the large-arc discharge by intervening proper cooling time, which cannot be actualized by a unipolar pulse mode because of the strong capacitive load characteristics but can be reached by an ambipolar pulse supply because the negative pulse period acts as cooling time. Using a discharge loop to remove the influence of load capacitive, a new type of pulse power supply for MAO is developed, so that the large-arc problem is resolved effectively, the film-forming efficiency is improved, and the pollution of the film and electrolyte caused by negative voltage is avoided.

关键词： micro-arc oxidation     local arc discharge     pulse power supply     magnesium alloy    

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Degradation of metronidazole by dielectric barrier discharge in an aqueous solution

Zhipeng Yang, Anxing Lai, Hangyu Chen, Youxiang Yan, Ye Yang, Weiwei Zhang, Lei Wang

《环境科学与工程前沿（英文）》 2019年 第13卷 第3期 doi: 10.1007/s11783-019-1117-4

摘要：

The discharge characteristics during the degradation of MNZ by DBD were investigated.

Increasing the discharge frequency can promote the degradation of MNZ.

MNZ removal reaches 99.1% at the initial concentration of 40 ppm within 120 min.

Coexisting organic matter inhibits the degradation of MNZ.

The energy efficiency of DBD for MNZ removal is higher than other technologies.

关键词： Dielectric barrier discharge     Antibiotic     Metronidazole     Water treatment    

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标题 作者 时间 类型 操作

Plasma-assisted oxidation of benzoic acid

Anna Khlyustova, Nikolay Sirotkin

期刊论文

Finite element modeling of thermo-active diaphragm walls

Yi RUI, Mei YIN

期刊论文

Parametric sensitivity analysis of cellular diaphragm wall

Xi CHEN, Wei XU

期刊论文

Diaphragm wall-soil-cap interaction in rectangular-closed- diaphragm-wall bridge foundations

Hua WEN, Qiangong CHENG, Fanchao MENG, Xiaodong CHEN

期刊论文

Power performance of circular piezoelectric diaphragm generators

TANG Kehong, KAN Junwu, YANG Zhigang, CHENG Guangming, PENG Taijiang

期刊论文

behavior of stiffened joints between concrete-filled steel tubular column and steel beam with narrow outer diaphragm

Chunyan QUAN,Wei WANG,Jian ZHOU,Rong WANG

期刊论文

Turbidity-adaptive underwater image enhancement method using image fusion

期刊论文

The behavior of a rectangular closed diaphragm wall when used as a bridge foundation

Qiangong CHENG, Jiujiang WU, Zhang SONG, Hua WEN

期刊论文

Soil arching effect of Lattice-Shaped Diaphragm Wall as bridge foundation

Jiujiang WU, Lingjuan WANG, Qiangong CHENG

期刊论文

水下交通隧道的设计与施工

王梦恕

期刊论文

Centrifuge experiment and numerical analysis of an air-backed plate subjected to underwater shock loading

Zhijie HUANG, Xiaodan REN, Zuyu CHEN, Daosheng LING

期刊论文

Effects of thermocline on performance of underwater glider’s power system propelled by ocean thermal

Hai YANG, Jie MA,

期刊论文

Detecting large-scale underwater cracks based on remote operated vehicle and graph convolutional neural

Wenxuan CAO; Junjie LI

期刊论文

Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

期刊论文

Degradation of metronidazole by dielectric barrier discharge in an aqueous solution

Zhipeng Yang, Anxing Lai, Hangyu Chen, Youxiang Yan, Ye Yang, Weiwei Zhang, Lei Wang

期刊论文