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Investigation of sediment transport pattern and beach morphology in the vicinity of submerged groyne

H. Afsoos Biria,M. A. Lashteh Neshaei,A. Ghabraei,M. A. Mehrdad

《结构与土木工程前沿(英文)》 2015年 第9卷 第1期   页码 82-90 doi: 10.1007/s11709-014-0275-5

摘要: Marine structures, such as Groynes, Sea walls and Detached Breakwaters, are constructed in coast of area to improve coast stability against bed erosions due to changing wave and current pattern. Marine mechanisms and interaction with the hydraulic structures need to be intensively studied. Groynes are one of the most prominent structures that are used in shore protection and littoral sediment. The main hydraulic function of the groyne is to control the long shore current and littoral sediment transport. This structure can be submerged and provide the necessary beach protection without negative aesthetic impact. However, for submerged structures adopted for beach protection, the shoreline response to these structures is not well understood. The objective of this study is to predict sediment transport in the vicinity of submerged groyne and comparison with non-submerged groyne focusing on a part of the coast at Dahane Sar Sefidrood, Guilan Province, Iran, where serious coast erosion has been occurred. The simulations were designed using a one-line model which can be used as a first approximation of shoreline prediction in the vicinity of groyne. The results of the proposed model are compared with experimental data to determine the shape of the coast. The results of predicted beach deformation show that when submerged groyne construct in the beach, sediment accumulation will be slightly less than the non-submerged groyne; because transfer coefficient for the submerged groyne is more than non-submerged groyne. This result will cause more sediment passing on submerged groyne. Finally, the result of the present study show that using submerged groyne is an efficient way to control the sediment and beach erosion without causing severe environmental effect on the coast.

关键词: submerged groyne     non-submerged groyne     beach morphology     Dahane Sar Sefidrood     sediment transport    

Restoration of hyper-eutrophic water with a modularized and air adjustable constructed submerged plant

Jinzhong LI, Xueju LI, Shujuan SUN, Xuegong LIU, Suiliang HUANG

《环境科学与工程前沿(英文)》 2011年 第5卷 第4期   页码 573-584 doi: 10.1007/s11783-011-0363-x

摘要: A modularized and air adjustable constructed submerged plant bed (CSPB) which can be used to restore the eutrophic water is introduced in this paper. This plant bed helps hydrophyte grow under poor conditions such as frequently changed water depth, impaired water transparency, algae bloom and substantial duckweed in summer, which are not naturally suitable for growing hydrophyte. This pilot study in Waihuan River of Tianjin, China, revealed that reduction of Chemical Oxygen Demand (COD), Total Nitrogen (TN) and Total Phosphorus (TP) by the use of CSPB could be reached 30%–35%, 35%–40%, 30%–40% respectively in the growing season (from March to October) and 5%–10%, 5%–15%, 7%–20% respectively in the winter (from November to February) when the detention time was 6 d. The relationships between the concentration of COD, TN, TP and the detention time fit the first-order kinetic equation well and the coefficients of determination ( ) were all above 0.9. The attenuation coefficients k of the kinetic equation were a function of the water temperature. When the water temperature was quite low or quite high, was not significantly changed with increasing or decreasing water temperature. While when the temperature was in a moderate range, an increase or decrease of water temperature would lead to a rapid increase or decrease in .

关键词: modularized and air adjustable constructed submerged plant bed     water purification     eco-restoration techniques     aquatic plants     eutrophication    

Dynamic performance of submerged floating tunnel with different mooring styles subjected to anchor cable

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0932-7

摘要: Submerged floating tunnels (SFTs) are novel structures for transportation across long- and deep-strait regions. Owing to severe wave and current excitation as well as the effects of underwater structures and corrosion, the risk of local anchor cable failure is high, which can result in the progressive failure of the entire structure. In this study, experimental and numerical investigations are conducted to analyze the dynamic behavior of an SFT with different mooring styles under local cable failure. A custom-designed cable failure device and the birth-and-death element method are used to simulate cable failure (i.e., progressive failure) via experiments and numerical simulation, respectively. A physical-scale segmental model of an SFT with different mooring styles under anchor cable failure is developed in this study. A segmental and entire-length mathematical model is developed using the ANSYS program to perform the numerical simulation. The results of the segmental numerical and experimental models indicate good agreement. The dynamic response of an SFT with different mooring styles under cable failure is comprehensively investigated by investigating the effects of key parameters (wave period, buoyant weight ratio, and cable failure mechanism). Moreover, the progressive failure of the SFT under cable failure is investigated via a segment model test and a numerical simulation of its entire length. The present study can serve as a reference for the safer designs of the SFT mooring style.

关键词: dynamic behaviors     submerged floating tunnel     cable failure     mooring style     progressive failure    

Performance of bioferric-submerged membrane bioreactor for dyeing wastewater treatment

ZOU Haiyan, XI Danli

《环境科学与工程前沿(英文)》 2007年 第1卷 第3期   页码 374-380 doi: 10.1007/s11783-007-0064-7

摘要: Adding iron salt or iron hydroxide to sludgemixed liquor in an aeration tank of a conventional activated sludge processes (bioferric process) can simultaneously improve the sludge s filterability and enhance the system s treatment capacity. In view of this, Fe(OH) was added to a submerged membrane bioreactor (SMBR) to enhance the removal efficiency and to mitigate membrane fouling. Bioferric process and SMBR were combined to create a novel process called Bioferric-SMBR. A side-by-side comparison study of Bioferric-SMBR and common SMBR dealing with dyeing wastewater was carried out. Bioferric-SMBR showed potential superiority, which could enhance removal efficiency, reduce membrane fouling and improve sludge characteristic. When volumetric loading rate was 25% higher than that of common SMBR, the removal efficiencies of Bioferric-SMBR on COD, dye, and NH-N were 1.0%, 9.5%, and 5.2% higher than that of common SMBR, respectively. The trans-membrane pressure of Bioferric-SMBR was only 36% of that in common SMBR while its membrane flux was 25% higher than that of common SMBR. The stable running period in Bioferric-SMBR was 2.5 times of that in common SMBR when there was no surplus sludge discharged. The mixed liquor suspended solids concentration of Bioferric-SMBR was higher than that of common SMBR with more diversified kinds of microorganisms such as protozoans and metazoans. The mean particle diameter and specific oxygen uptake rate of Bioferric-SMBR were 3.10 and 1.23 times the common SMBR, respectively.

关键词: hydroxide     surplus     aeration     SMBR     Bioferric process    

The role of single deformed bubble on porous foam tray with submerged orifices on the mass transfer enhancement

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 2127-2143 doi: 10.1007/s11705-023-2363-3

摘要: Foam trays with porous submerged orifices endow bubbles uniformly distributed, which are considered attractive column internals to enhance the gas-liquid mass transfer process. However, its irregular orifice and complex gas-liquid flow make it lack pore-scale investigations concerning the transfer mechanism of dynamic bubbling. In this work, the actual porous structure of the foam tray is obtained based on micro computed tomography technology. The shape, dynamic, and mass transfer of rising bubbles at porous orifices are investigated using the volume of fluid and continue surface force model. The results demonstrate that the liquid encroaching on the gas channels causes the increasing orifices velocity, which makes the trailing bubble easily detach from the midst of the leading bubble and causes pairing coalescence. Additionally, we found that the central breakup regimes significantly improve the gas-liquid interface area and mass transfer efficiency. This discovery exemplifies the mechanism of mass transfer intensification for foam trays and serves to promote its further development.

关键词: bubble formation     porous submerged orifices     process intensification     foam tray    

Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1480-1493 doi: 10.1007/s11709-021-0776-y

摘要: In waterfront geotechnical engineering, seismic and drainage conditions must be considered in the design of retaining structures. This paper proposes a general analytical method to evaluate the seismic active earth pressure on a retaining wall with backfill subjected to partial steady seepage flow under seismic conditions. The method comprises the following steps: i) determination of the total head, ii) upper bound solution of seismic active earth thrust, and iii) deduction for the earth pressure distribution. The determination of total head h(x,z) relies on the Fourier series expansions, and the expressions of the seismic active earth thrust and pressure are derived by using the upper bound theorem. Parametric studies reveal that insufficient drainage and earthquakes are crucial factors that cause unfavorable earth pressure. The numerical results confirm the validity of the total head distribution. Comparisons indicate that the proposed method is consistent with other relevant existing methods in terms of predicting seismic active earth pressure. The method can be applied to the seismic design of waterfront retaining walls.

关键词: seismic active earth pressure     partial seepage flow     pore pressure     anisotropy     upper bound theorem    

Submerged arc plasma system combined with ozone oxidation for the treatment of wastewater containing

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-020-1384-0

摘要:

• Submerged arc plasma was introduced in terms of wastewater treatment.

关键词: Thermal plasma     Submerged arc plasma     Wastewater     Ozone     Phenol     Highly energetic electron    

潜运沉管建闸方法

周君亮

《中国工程科学》 2000年 第2卷 第11期   页码 78-83

摘要:

潜运沉管建闸适用在航运发达的顺直河道上建设水工建筑物。闸位取在原来航道上,闸室和闸门口径可以与航道等宽,运行期不碍航;闸室的钢筋混凝土的浇筑,预埋、闸门和启闭设备的安装和调试等都可在预制场内完成;预制场灌水后,确定闸身潜运时的有效质量和底板底高程,使潜运及在航道内的定位工作十分简便;可以水上拆装和动水开关闸门;施工风险小,施工期短,临时工程少,工程造价省。

关键词: 潜运沉管     建闸方法     水上拆装闸门    

Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model

Fangyue LI, Joachim BEHRENDT, Knut WICHMANN, Ralf OTTERPOHL

《环境科学与工程前沿(英文)》 2009年 第3卷 第2期   页码 226-235 doi: 10.1007/s11783-009-0008-5

摘要: In this study, a mathematical model was established to predict the formation of the soluble microbial product (SMP) in a submerged membrane bioreactor. The developed model was calibrated under the reference condition. Simulation results were in good agreement with the measured results under the reference condition. The calibrated model was then used in the scenario studies to evaluate the effect of three chosen operating parameters: hydraulic retention time (HRT), dissolved oxygen concentration, and sludge retention time (SRT). Simulation results revealed that the SMP dominated the soluble organic substances in the supernatant. The scenario studies also revealed that the HRT can be decreased to 1 h without deteriorating the effluent quality; dissolved oxygen concentration in the reactor can be kept at 2-3 mg/L to maintain the effluent quality, reduce the content of SMP, and minimize operating costs; the optimal SRT can be controlled to 10-15 d to achieve complete nitrification process, less membrane fouling potential, and acceptable organic removal efficiency.

关键词: hybrid activated sludge model (ASM)     membrane bioreactor (MBR)     soluble microbial product (SMP)    

用改进的Boussinesq方程模拟潜堤上的波浪变形

郑永红,沈永明,吴修广,游亚戈

《中国工程科学》 2004年 第6卷 第4期   页码 34-40

摘要:

研究了一种改进的Boussinesq方程,采用预报校正格式对该方程进行了数值离散,并对淹没潜堤上的波浪变形进行了数值模拟,从数值模拟结果和实测值的比较结果来看,该方程能较好地模拟波浪在潜堤上传播时波面的变形过程,可以用于实际中的波浪问题计算。这种改进的Boussinesq方程本身及其求解方法需做进一步的完善。研究结果为实际应用Boussinesq方程来研究复杂地形上的波浪传播提供一定的理论指导。

关键词: 改进的Boussinesq方程     数值模拟     波浪变形     潜堤    

ratio and alcohol ethoxylate dosage on methane production in treatment of low-strength wastewater by a submerged

Yulun Nie, Xike Tian, Zhaoxin Zhou, Yu-You Li

《环境科学与工程前沿(英文)》 2017年 第11卷 第6期 doi: 10.1007/s11783-017-0947-1

摘要: The effects of food to microorganism (F/M) ratio and alcohol ethoxylate (AE) dosage on the methane production potential were investigated in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor (SAnMBR). The fate of AE and its acute and/or chronic impact on the anaerobic microbes were also analyzed. The results indicated that AE had an inhibitory effect to methane production potential (lag-time depends on the AE dosage) and the negative effect attenuated subsequently and methane production could recover at F/M ratio of 0.088–0.357. VFA measurement proved that AE was degraded into small molecular organic acids and then converted into methane at lower F/M ratio (F/M<0.158). After long-term acclimation, anaerobic microbe could cope with the stress of AE by producing more EPS (extracellular polymeric substances) and SMP (soluble microbial products) due to its self-protection behavior and then enhance its tolerance ability. However, the methane production potential was considerably decreased when AE was present in wastewater at a higher F/M ratio of 1.054. Higher AE amount and F/M ratio may destroy the cell structure of microbe, which lead to the decrease of methane production activity of sludge and methane production potential.

关键词: Anaerobic membrane bioreactor AnMBR     F/M ratio     Surfactant     Wastewater     Methane production     Influence    

Energy reduction of a submerged membrane bioreactor using a polytetrafluoroethylene (PTFE) hollow-fiber

Taro Miyoshi, Thanh Phong Nguyen, Terumi Tsumuraya, Hiromu Tanaka, Toru Morita, Hiroki Itokawa, Toshikazu Hashimoto

《环境科学与工程前沿(英文)》 2018年 第12卷 第3期 doi: 10.1007/s11783-018-1018-y

摘要: In this study, we modified a polytetrafluoroethylene (PTFE) hollow-fiber membrane element used for submerged membrane bioreactors (MBRs) to reduce the energy consumption during MBR processes. The high mechanical strength of the PTFE membrane made it possible to increase the effective length of the membrane fiber from 2 to 3 m. In addition, the packing density was increased by 20% by optimizing the membrane element configuration. These modifications improve the efficiency of membrane cleaning associated with aeration. The target of specific energy consumption was less than 0.4 kWh·m in this study. The continuous operation of a pilot MBR treating real municipal wastewater revealed that the MBR utilizing the modified membrane element can be stably operated under a specific air demand per membrane surface area (SAD ) of 0.13 m ·m ·hr when the daily-averaged membrane fluxes for the constant flow rate and flow rate fluctuating modes of operation were set to 0.6 and 0.5 m ·m ·d , respectively. The specific energy consumption under these operating conditions was estimated to be less than 0.37 kWh·m . These results strongly suggest that operating an MBR equipped with the modified membrane element with a specific energy consumption of less than 0.4 kWh·m is highly possible.

关键词: Energy-saving     Membrane bioreactor     Polytetrafluoroethylene (PTFE) membrane     Hollow fiber     Power consumption    

Synthesis of Ag and Cd nanoparticles by nanosecond pulsed discharge in liquid nitrogen

Mahmoud Trad, Alexandre Nominé, Natalie Tarasenka, Jaafar Ghanbaja, Cédric Noël, Malek Tabbal, Thierry Belmonte

《化学科学与工程前沿(英文)》 2019年 第13卷 第2期   页码 360-368 doi: 10.1007/s11705-019-1802-7

摘要: The synthesis of CdO, Ag O (5 nm) and Ag (~20‒30 nm) nano-objects is achieved simultaneously by nanosecond-pulsed discharges in liquid nitrogen between one cadmium electrode and one silver electrode. Oxidation occurs when liquid nitrogen is fully evaporated and nanoparticles are in contact with the air. No alloy is formed, whatever the conditions, even though both elements are present simultaneously, as showed by time-resolved optical emission spectroscopy. This lack of reactivity between elements is attributed to the high pressure within the discharge that keeps each metallic vapor around the electrode it comes from. Each element exhibits a specific behavior. Cubic Cd particles, formed at 4 kV, get elongated with filamentary tips when the applied voltage reaches 7 and 10 kV. Cd wires are formed by assembly in liquid nitrogen of Cd nanoparticles driven by dipole assembly, and not by dielectrophoresis. On the contrary, silver spherical particles get assembled into 2D dendritic structures. The anisotropic growth of these structures is assumed to be due to the existence of pressure gradients.

关键词: spark discharges     submerged discharges     time-resolved optical emission spectroscopy     liquid nitrogen    

长江越江通道工程应实行桥隧并举

钱七虎,何益寿

《中国工程科学》 2001年 第3卷 第5期   页码 32-34

摘要:

长江越江交通通道工程对我国21世纪经济的稳定发展作用巨大,因此在越江交通通道工程方案的选择上不能唯桥是举,而要因地制宜和恰到好处地发挥桥梁和水下隧道各自的优势,总体上实行桥隧并举。

关键词: 长江越江交通通道     工程     桥梁     水下隧道    

标题 作者 时间 类型 操作

Investigation of sediment transport pattern and beach morphology in the vicinity of submerged groyne

H. Afsoos Biria,M. A. Lashteh Neshaei,A. Ghabraei,M. A. Mehrdad

期刊论文

Restoration of hyper-eutrophic water with a modularized and air adjustable constructed submerged plant

Jinzhong LI, Xueju LI, Shujuan SUN, Xuegong LIU, Suiliang HUANG

期刊论文

Dynamic performance of submerged floating tunnel with different mooring styles subjected to anchor cable

期刊论文

Performance of bioferric-submerged membrane bioreactor for dyeing wastewater treatment

ZOU Haiyan, XI Danli

期刊论文

The role of single deformed bubble on porous foam tray with submerged orifices on the mass transfer enhancement

期刊论文

Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

期刊论文

Submerged arc plasma system combined with ozone oxidation for the treatment of wastewater containing

期刊论文

潜运沉管建闸方法

周君亮

期刊论文

Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model

Fangyue LI, Joachim BEHRENDT, Knut WICHMANN, Ralf OTTERPOHL

期刊论文

用改进的Boussinesq方程模拟潜堤上的波浪变形

郑永红,沈永明,吴修广,游亚戈

期刊论文

ratio and alcohol ethoxylate dosage on methane production in treatment of low-strength wastewater by a submerged

Yulun Nie, Xike Tian, Zhaoxin Zhou, Yu-You Li

期刊论文

Energy reduction of a submerged membrane bioreactor using a polytetrafluoroethylene (PTFE) hollow-fiber

Taro Miyoshi, Thanh Phong Nguyen, Terumi Tsumuraya, Hiromu Tanaka, Toru Morita, Hiroki Itokawa, Toshikazu Hashimoto

期刊论文

Synthesis of Ag and Cd nanoparticles by nanosecond pulsed discharge in liquid nitrogen

Mahmoud Trad, Alexandre Nominé, Natalie Tarasenka, Jaafar Ghanbaja, Cédric Noël, Malek Tabbal, Thierry Belmonte

期刊论文

长江越江通道工程应实行桥隧并举

钱七虎,何益寿

期刊论文