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The effect of texture and irrigation on the soil moisture vertical-temporal variability in an urban artificial

Xiaofeng ZHANG,Xu ZHANG,Guanghe LI

《环境科学与工程前沿(英文)》 2015年 第9卷 第2期   页码 269-278 doi: 10.1007/s11783-014-0672-y

摘要: Soil moisture variability in natural landscapes has been widely studied; however, less attention has been paid to its variability in the urban landscapes with respect to the possible influence of texture stratification and irrigation management. Therefore, a case study was carried out in the Beijing Olympic Forest Park to continuously monitor the soil in three typical profiles from 26 April to 11 November 2010. The texture stratification significantly affected the vertical distribution of moisture in the non-irrigated profile where moisture was mostly below field capacity. In the profile where irrigation was sufficient to maintain moisture above field capacity, gravity flow led to increased moisture with depth and thus eliminated the influence of texture. In the non-irrigated sites, the upper layer (above 80 cm) exhibited long-term moisture persistence with the time scale approximating the average rainfall interval. However, a coarse-textured layer weakened the influence of rainfall, and a fine-textured layer weakened the influence of evapotranspiration, both of which resulted in random noise-like moisture series in the deeper layers. At the irrigated site, frequent irrigation neutralized the influence of evapotranspiration in the upper layer (above 60 cm) and overshadowed the influence of rainfall in the deeper layer. As a result, the moisture level in the upper layer also behaved as a random noise-like series; whereas due to deep transpiration, the moisture of the deep layer had a persistence time-scale longer than a month, consistent with characteristic time-scales found for deep transpiration.

关键词: moisture vertical distribution     moisture temporal variation     texture stratification     irrigation     meteorological forcing     urban landscape    

Reliability analysis of the control system of large-scale vertical mixing equipment

YANG Mingjin, LI Xiwen, LI Shaoping, YANG Shuzi

《机械工程前沿(英文)》 2008年 第3卷 第2期   页码 133-138 doi: 10.1007/s11465-008-0037-y

摘要: The control system of vertical mixing equipment is a concentrate distributed monitoring system (CDMS). A reliability analysis model was built and its analysis was conducted based on reliability modeling theories such as the graph theory, Markov process, and redundancy theory. Analysis and operational results show that the control system can meet all technical requirements for high energy composite solid propellant manufacturing. The reliability performance of the control system can be considerably improved by adopting a control strategy combined with the hot spared redundancy of the primary system and the cold spared redundancy of the emergent one. The reliability performance of the control system can be also improved by adopting the redundancy strategy or improving the quality of each component and cable of the system.

关键词: composite     redundancy     monitoring     vertical     technical    

Performance of vertical axis water turbine with eye-shaped baffle for pico hydropower

Zhuohuan HU, Dongcheng WANG, Wei LU, Jian CHEN, Yuwen ZHANG

《能源前沿(英文)》 2022年 第16卷 第4期   页码 683-696 doi: 10.1007/s11708-020-0689-9

摘要: A series of inline pico hydropower systems, which could be used in confined space, especially for water distribution networks (WDNs), was designed and investigated. The turbine with an eye-shaped vertical water baffle was developed to evaluate the hydraulic performance. A three-dimensional dynamic mesh was employed and the inlet velocity was considered as the inlet boundary condition, whereas the outlet boundary was set as the outflow. Then, numerical simulations were conducted and the standard turbulence model was found to be the best capable of predicting flow features through the comparison with the experimental results. The effects of the opening diameter of the water baffle and installation angle of the rotor on the flow field in the turbine were investigated. The results suggested that the water baffle opening at = 30 mm and the rotor at a 52° angle could achieve the highest efficiency of 5.93%. The proper eye-shaped baffle not only accelerates the fluid flow and generates positive hydrodynamic torque, but also eliminates the flow separation. The scheme proposed in this paper can be exploited for practical applications in the water pipelines at various conditions and power requirements.

关键词: vertical axis water turbine     eye-shaped     vertical water baffle     pico hydropower    

Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and

Shuvankar DAS; Debarghya CHAKRABORTY

《结构与土木工程前沿(英文)》 2022年 第16卷 第8期   页码 1040-1055 doi: 10.1007/s11709-022-0841-1

摘要: In the present study, the stability of a vertical rock escarpment is determined by considering the influence of undercut. Lower bound finite element limit analysis in association with Power Cone Programming (PCP) is applied to incorporate the failure of rock mass with the help of the Generalized Hoek-Brown yield criterion. The change in stability due to the presence of undercut is expressed in terms of a non-dimensional stability number (σci/γH). The variations of the magnitude of σci/γH are presented as design charts by considering the different magnitudes of undercut offset (H/vu and wu/vu) from the vertical edge and different magnitudes of Hoek-Brown rock mass strength parameters (Geological Strength Index (GSI), rock parameter (mi,), Disturbance factor (D)). The obtained results indicate that undercut can cause a severe stability problem in rock mass having poor strength. With the help of regression analysis of the computed results, a simplified design equation is proposed for obtaining σci/γH. By performing sensitivity analysis for an undisturbed vertical rock escarpment, we have found that the undercut height ratio (H/vu) is the most sensitive parameter followed by GSI, undercut shape ratio (wu/vu), and mi. The developed design equation as well as design charts can be useful for practicing engineers to determine the stability of the vertical rock escarpment in the presence of undercut. Failure patterns are also presented to understand type of failure and extent of plastic state during collapse.

关键词: undercut     vertical escarpment     stability     Hoek-Brown yield criterion     PCP    

Evacuation strategies for vertical ship lift during initial fire: Integrated application of stairs and

Shu CHEN, Menghan SHANG, Jianping WANG

《工程管理前沿(英文)》 2021年 第8卷 第1期   页码 135-147 doi: 10.1007/s42524-020-0125-1

摘要: Vertical ship lifts (VSLs) are widely used in navigation facilities worldwide because of their efficiency and low cost. Although several researchers have investigated fire evacuation strategies for reducing potential safety hazards in VSLs, an effective and integrated application of stairs and elevators when a fire occurs in a VSL is necessary. Several evacuation routes were analyzed according to VSL structure and evacuation times in this study. Objective function corresponding to the minimum vertical evacuation time and related simulation model was subsequently developed to obtain a cooperative evacuation plan considering different numbers of evacuees. The Three Gorges ship lift was used as an example, and simulation results indicate that number of evacuees and exit selection are the main influencing factors of the total evacuation time in the stair- and elevator-coordinated evacuation mode. Furthermore, the distance between people trapped in ship reception chamber and evacuation exits affects evacuees’ choice of exits. The proposed model can provide a theoretical reference for evacuation research during initial fire events in VSLs.

关键词: vertical ship lift     initial fire     fire evacuation     numerical simulation     stair     elevator    

Removal of arsenic by pilot-scale vertical flow constructed wetland

《环境科学与工程前沿(英文)》 2021年 第15卷 第4期 doi: 10.1007/s11783-021-1435-1

摘要:

• VFCWs are effective for the treatment of arsenic-containing wastewater.

关键词: Constructed wetland     Arsenic     Removal efficiency     Mass balance    

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    

Decontamination efficiency and root structure change in the plant-intercropping model in vertical-flow

Yonghua CHEN, Xiaofu WU, Mingli CHEN, Kelin LI, Jing PENG, Peng ZHAN

《环境科学与工程前沿(英文)》 2013年 第7卷 第6期   页码 906-912 doi: 10.1007/s11783-013-0579-z

摘要: Subtropical climatic conditions can contribute to the death of the aerial parts of constructed wetland plants in winter. This presents a barrier to the widespread application of constructed wetland and is an issue that urgently needs to be solved. Three contrasting experiments, the plant-intercropping model (A), the warm-seasonal plant model (B), and the non-plant model (C), were studied in terms of their efficiency in removing pollutants, and the change in root structure of plants in the plant-intercropping model within the vertical-flow constructed wetlands. The results indicate that model A was able to solve the aforementioned problem. Overall, average removal rates of three pollutants (COD , total nitrogen (TN) and total phosphorous (TP)) using model A were significantly higher than those obtained using models B and C ( <0.01). Moreover, no significant differences in removal rates of the three pollutants were detected between A and B during the higher temperature part of the year ( >0.05). Conversely, removal rates of the three pollutants were found to be significantly higher using model A than those observed using model B during the lower temperature part of the year ( <0.01). Furthermore, the morphologies and internal structures of plant roots further demonstrate that numerous white roots, whose distribution in soil was generally shallow, extend further under model A. The roots of these aquatic plants have an aerenchyma structure composed of parenchyma cells, therefore, roots of the cold-seasonal plants with major growth advantages used in A were capable of creating a more favorable vertical-flow constructed wetlands media-microenvironment. In conclusion, the plant-intercropping model (A) is more suitable for use in the cold environment experienced by constructed wetland during winter.

关键词: vertical-flow constructed wetlands     plant intercropping model     warm seasonal plant model    

Combined reticular blind drainage and vertical hierarchical drainage system for landfills located in

Wenjing LU,Zhonge FU,Yan ZHAO

《环境科学与工程前沿(英文)》 2016年 第10卷 第1期   页码 177-184 doi: 10.1007/s11783-014-0710-9

摘要: A novel water control technology that combines the features of a reticular blind drainage system and a vertical hierarchical drainage system is developed and applied in the Yanziyan Sanitary Landfill, which is located at an area (Loudi City, Hunan Province, China) with high rainfall and high groundwater level. The reticular blind drain system, which was installed on the bottom and side walls of the landfill site, can conveniently guide the flow of groundwater out of the site while preventing a disorganized flow of groundwater. The vertical hierarchical drainage system was installed to separate rainfall water and leachate in the landfill site, thus efficiently reducing the pressure of leachate treatment. The whole drainage system plays a key role in foundation stabilization by seepage control and separation and in the instant drainage of rainfall water. The leachate reduction efficiency of the drainage technology was calculated in terms of leachate production before (336519 m ) and after (29664 m ) technology application. Over 90% of leachate derived from rainfall water and groundwater inflow was avoided upon installation of the vertical hierarchical drainage and reticular blind drainage systems. The technology can thus be popularized and applied for water control in landfills located in areas with high rainfall and high groundwater level. The proposed technology can be used to alleviate the pressure of leachate treatment and to reduce the risk of instability.

关键词: landfill     reticular blind drain     vertical hierarchical drain     guidance and drainage     impermeable layer    

A novel ensemble model for predicting the performance of a novel vertical slot fishway

Aydin SHISHEGARAN, Mohammad SHOKROLLAHI, Ali MIRNOROLLAHI, Arshia SHISHEGARAN, Mohammadreza MOHAMMAD KHANI

《结构与土木工程前沿(英文)》 2020年 第14卷 第6期   页码 1418-1444 doi: 10.1007/s11709-020-0664-x

摘要: We investigate the performance of a novel vertical slot fishway by employing finite volume and surrogate models. Multiple linear regression, multiple log equation regression, gene expression programming, and combinations of these models are employed to predict the maximum turbulence, maximum velocity, resting area, and water depth of the middle pool in the fishway. The statistical parameters and error terms, including the coefficient of determination, root mean square error, normalized square error, maximum positive and negative errors, and mean absolute percentage error were employed to evaluate and compare the accuracy of the models. We also conducted a parametric study. The independent variables include the opening between baffles ( ), the ratio of the length of the large and small baffles, the volume flow rate, and the angle of the large baffle. The results show that the key parameters of the maximum turbulence and velocity are the volume flow rate and .

关键词: novel vertical slot fishway     parametric study     finite volume method     ensemble model     gene expression programming    

Cracking resistance performance of super vertical-distance pumped SFRC

JIANG Jinyang, SUN Wei, ZHANG Yunsheng, CHEN Cuicui, WANG Jing

《结构与土木工程前沿(英文)》 2008年 第2卷 第2期   页码 179-183 doi: 10.1007/s11709-008-0018-6

摘要: The mix ratio of steel fiber reinforced concrete (SFRC) was optimized using the principles that workability must meet the pumping demand and anti-cracking performance should be optimal. The effect of SFRC on the initial cracking load, the ultimate load and the crack width of the reinforced concrete (RC) member were analyzed in this paper. It was found that the admixture had good preservation of moisture and adhesion and the fibers distributed homogeneously in one hour out of the machine. According to the pumping results, the SFRC could be pumped vertically up to 306 m. Based on the standard computation formula of cracks, the maximum crack width of an RC member with 0.8% steel fiber (by volume) is about 32% lower than that of standard RC member. Through an experimental research on full-scale model tests for the steel and concrete composite anchorage zone on a pylon, the SFRC not only remarkably increases the crack resistance and the ultimate load, but the initial load also improves 33% approximately. It is also indicated that plastic shrinkage cracking of SFRC in which volume fraction of steel fibers is 0.8% can be restrained obviously and the unrestrained drying shrinkage can be diminished by about 50% at early age. The results confirmed that the SFRC can lessen the shrinkage crack of concrete and enhance markedly the direct tensile strength. Therefore, the SFRC can solve the key question of crack resistance for the anchorage zone of a bridge tower.

Nucleate boiling in two types of vertical narrow channels

Lei GUO, Shusheng ZHANG, Lin CHENG

《能源前沿(英文)》 2011年 第5卷 第3期   页码 250-256 doi: 10.1007/s11708-010-0128-4

摘要: To explore the mechanism of boiling bubble dynamics in narrow channels, we investigate 2-mm wide I- and Z-shaped channels. The influence of wall contact angle on bubble generation and growth is studied using numerical simulation. The relationships between different channel shapes and the pressure drop are also examined, taking into account the effects of gravity, surface tension, and wall adhesion. The wall contact angle imposes considerable influence over the morphology of bubbles. The smaller the wall contact angle, the rounder the bubbles, and the less time the bubbles take to depart from the wall. Otherwise, the bubbles experience more difficulty in departure. Variations in the contact angle also affect the heat transfer coefficient. The greater the wall contact angle, the larger the bubble-covered area. Therefore, wall thermal resistance increases, bubble nucleation is suppressed, and the heat transfer coefficient is lowered. The role of surface tension in boiling heat transfer is considerably more important than that of gravity in narrow channels. The generation of bubbles dramatically disturbs the boundary layer, and the bubble bottom micro-layer can enhance heat transfer. The heat transfer coefficient of Z-shaped channels is larger than that of the I-shaped type, and the pressure drop of the former is clearly higher.

关键词: nucleate boiling     narrow channel     numerical simulation     bubble dynamics    

Co-pyrolysis of oil sludge with hydrogen-rich plastics in a vertical stirring reactor: Kinetic analysis

《环境科学与工程前沿(英文)》 2022年 第16卷 第10期 doi: 10.1007/s11783-022-1570-3

摘要:

● Collaborative treatment of plastics and OS was established to improve oil quality.

关键词: Oily sludge     Pyrolysis     Polyethylene     H/Ceff ratio     Oil quality    

Correction to: Effect of undercut on the lower bound stability of vertical rock escarpment using finite

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0035-5

摘要: Correction to: Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and power cone programming

关键词: finite element power     stability rock escarpment    

Experimental study on the progressive failure and its anchoring effect of weak-broken rock vertical slope

Hehua ZHU, Qianwei XU, Wenqi DING, Feng HUANG

《结构与土木工程前沿(英文)》 2011年 第5卷 第2期   页码 208-224 doi: 10.1007/s11709-011-0111-0

摘要: To improve the understanding on the failure behavior and its anchoring effect of weak-broken rock slope, the rock of grade IV according to China is taken as reference prototype, and a series of model tests were carried out in laboratory. These tests can be divided into two categories, that is, with bolt reinforcement and without bolt reinforcement. In which, the stability of slope reinforced with different bolt diameter, different anchor length and different space are studied. The test results show that the collapse of slope is the combination of tension failure at the top and the compression-shearing failure at the bottom of the slope, and its failure process presents progressive characteristics. The contributions of bolt reinforcement are mainly reflected by the aspects of shear resistance, crack resistance and anti-extension. The reinforcement of blot not only can improve the vertical bearing capacity before failure, but also can reduce the vertical settlement and allow greater lateral rock wall deformation; what is more, the stress concentration degree in rock mass can be dispersed, which do help to improve the stability of slope rock mass.

关键词: progressive failure     weak-broken rock     slope     model test     bolt    

标题 作者 时间 类型 操作

The effect of texture and irrigation on the soil moisture vertical-temporal variability in an urban artificial

Xiaofeng ZHANG,Xu ZHANG,Guanghe LI

期刊论文

Reliability analysis of the control system of large-scale vertical mixing equipment

YANG Mingjin, LI Xiwen, LI Shaoping, YANG Shuzi

期刊论文

Performance of vertical axis water turbine with eye-shaped baffle for pico hydropower

Zhuohuan HU, Dongcheng WANG, Wei LU, Jian CHEN, Yuwen ZHANG

期刊论文

Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and

Shuvankar DAS; Debarghya CHAKRABORTY

期刊论文

Evacuation strategies for vertical ship lift during initial fire: Integrated application of stairs and

Shu CHEN, Menghan SHANG, Jianping WANG

期刊论文

Removal of arsenic by pilot-scale vertical flow constructed wetland

期刊论文

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

期刊论文

Decontamination efficiency and root structure change in the plant-intercropping model in vertical-flow

Yonghua CHEN, Xiaofu WU, Mingli CHEN, Kelin LI, Jing PENG, Peng ZHAN

期刊论文

Combined reticular blind drainage and vertical hierarchical drainage system for landfills located in

Wenjing LU,Zhonge FU,Yan ZHAO

期刊论文

A novel ensemble model for predicting the performance of a novel vertical slot fishway

Aydin SHISHEGARAN, Mohammad SHOKROLLAHI, Ali MIRNOROLLAHI, Arshia SHISHEGARAN, Mohammadreza MOHAMMAD KHANI

期刊论文

Cracking resistance performance of super vertical-distance pumped SFRC

JIANG Jinyang, SUN Wei, ZHANG Yunsheng, CHEN Cuicui, WANG Jing

期刊论文

Nucleate boiling in two types of vertical narrow channels

Lei GUO, Shusheng ZHANG, Lin CHENG

期刊论文

Co-pyrolysis of oil sludge with hydrogen-rich plastics in a vertical stirring reactor: Kinetic analysis

期刊论文

Correction to: Effect of undercut on the lower bound stability of vertical rock escarpment using finite

期刊论文

Experimental study on the progressive failure and its anchoring effect of weak-broken rock vertical slope

Hehua ZHU, Qianwei XU, Wenqi DING, Feng HUANG

期刊论文