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Embankment dam foundation analysis for the decrease of internal erosion likelihood

Marc SMITH

《结构与土木工程前沿（英文）》 2012年第6卷第4期页码 431-436 doi: 10.1007/s11709-012-0183-5

摘要： A zoned embankment dam is founded on clay underlain by a sand deposit. Major seepage phenomena were noticed in the foundation downstream from the dam where the vertical seepage forces in the sand layer were expected to exceed the downward forces due to the overlying clay. Modern technologies were applied to delineate critical zones to help design optimal rehabilitation measures. A global electromagnetic survey was carried out to detect and map the main sources, pathways and exits of seepage. Based on these global findings, a more detailed analysis was then conducted to identify zones where thickness of the foundation clay is minimal, pore pressures in sand are higher and thus where the factor of safety against uplift is lower and internal erosion is more likely to occur. Clay thickness evaluation required the determination of land surface as well as clay-sand contact elevations. A laser airborne survey was performed to model the land surface elevation. Data concerning the clay-sand contact elevation came from the interpreted stratigraphy based on a series of boreholes and cone penetration tests. This data was combined in a geostatistical model along with the measured piezometric levels in the foundation. This resulted in a contour map showing factors of safety against uplift over the entire downstream area. The use of modern technologies, namely electromagnetic and laser surveys as well as geostatistical tools, was instrumental in defining the limits of an otherwise spread-out problem and to provide an optimal solution, in terms of costs and effectiveness, for the long-term stabilization of the foundation.

关键词： seepage detection geostatistical analysis dam monitoring internal erosion LIDAR survey

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3D finite element method (FEM) simulation of groundwater flow during backward erosion piping

Kristine VANDENBOER,Vera van BEEK,Adam BEZUIJEN

《结构与土木工程前沿（英文）》 2014年第8卷第2期页码 160-166 doi: 10.1007/s11709-014-0257-7

摘要： Backward erosion piping is an important failure mechanism for cohesive water retaining structures which are founded on a sandy aquifer. At present, the prediction models for safety assessment are often based on 2D assumptions. In this work, a 3D numerical approach of the groundwater flow leading to the erosion mechanism of backward erosion piping is presented and discussed. Comparison of the 2D and 3D numerical results explicitly demonstrates the inherent 3D nature of the piping phenomenon. In addition, the influence of the seepage length is investigated and discussed for both piping initiation and piping progression. The results clearly indicate the superiority of the presented 3D numerical model compared to the established 2D approach. Moreover, the 3D numerical results enable a better understanding of the complex physical mechanism involved in backward erosion piping and thus can lead to a significant improvement in the safety assessment of water retaining structures.

关键词： backward erosion piping groundwater flow 3D finite element method (FEM)

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Cylindrical particulate internal flows: A review

Lizhong HUANG, Xiang GAO, Jianzhong LIN

《机械工程前沿（英文）》 2012年第7卷第4期页码 385-393 doi: 10.1007/s11465-012-0354-z

摘要：

The study of cylindrical particulate internal flows has wide industrial applicability hence received much attention. This article reviews the cylindrical particulate internal flows over the past twenty years. The research is related to the cylindrical particulate flows in the straight channel, curved channel and rotational channel. Finally, several open research issues have been identified.

关键词： cylindrical particulate flow internal flow

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Current progress on internal medicine in China—2006 Part I

YAO Dingkang, ZHU Liang, ZHAO Xue, MEI Changlin

《医学前沿（英文）》 2007年第1卷第3期页码 235-247 doi: 10.1007/s11684-007-0046-y

摘要： The growing interest has been placed in the current state of Chinaºs internal medicine from all over the world. Many data of internal medicine in China were collected by searching through some of the most prominent medical magazines published in China in 2006. Because there are many researches on the field of internal medicine, just some representative reports focusing on this topic were selected in this paper. In part I of this study, a summary of the advances made in cardiology, respiration diseases, and gastroenterology was presented.

关键词： internal medicine Chinaºs internal respiration gastroenterology cardiology

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Unified cycle model of a class of internal combustion engines and their optimum performance characteristics

Shiyan ZHENG

《能源前沿（英文）》 2011年第5卷第4期页码 367-375 doi: 10.1007/s11708-011-0170-x

摘要： The unified cycle model of a class of internal combustion engines is presented, in which the influence of the multi-irreversibilities mainly resulting from the adiabatic processes, finite-time processes and heat leak loss through the cylinder wall on the performance of the cycle are taken into account. Based on the thermodynamic analysis method, the mathematical expressions of the power output and efficiency of the cycle are calculated and some important characteristic curves are given. The influence of the various design parameters such as the high-low pressure ratio, the high-low temperature ratio, the compression and expansion isentropic efficiencies etc. on the performance of the cycle is analyzed. The optimum criteria of some important parameters such as the power output, efficiency and pressure ratio are derived. The results obtained from this unified cycle model are very general and useful, from which the optimal performance of the Atkinson, Otto, Diesel, Dual and Miller heat engines and some new heat engines can be directly derived.

关键词： internal combustion engine irreversibility power output efficiency optimization

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抗磨蚀材料失效过程的微观特性

王飚,王宇栋,张自华,何筱奎,诸小丽

《中国工程科学》 2001年第3卷第8期页码 82-86

摘要：

用光学显微镜、扫描电镜、电子探针和X射线衍射，对抗汽蚀较优的硼不锈钢堆焊层和抗磨蚀较优的碳化钨陶瓷堆焊层的原样、汽蚀后样和磨蚀后样进行了微观分析研究。结果表明，硼不锈钢堆焊层是较好的抗汽蚀材料，但抗磨蚀效果不理想；碳化钨对磨蚀损坏有良好的屏障作用；磨蚀坑是气泡溃灭产生的脉冲式法向负压力和脉冲式泥沙冲击切向分力联合作用的结果。

关键词：抗汽蚀抗磨蚀微观特性

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Effect of land use and land cover change on soil erosion and the spatio-temporal variation in Liupan

Bin QUAN, M. J. M. R?MKENS, Rui LI, Fang WANG, Jie CHEN

《环境科学与工程前沿（英文）》 2011年第5卷第4期页码 564-572 doi: 10.1007/s11783-011-0348-9

摘要： The Liupan Mountains are located in the southern Ningxia Hui Autonomous Region of China, that forms an important divide between landforms and bio-geographic regions. The populated part of the Liupan Mountain Region has suffered tremendous ecological damage over time due to population pressure, excessive demand and inappropriate use of agricultural land resources. To present the relationship between land use/cover change and spatio-temporal variation of soil erosion, data sets of land use between the late 1980s and 2000 were obtained from Landsat Thematic Mapper (TM) imagery, and spatial models were used to characterize landscape and soil erosion conditions. Also, soil erosion in response to land use and land cover change were quantified and analyzed using data from geographical information systems and remote sensing. Soil erosion by water was the dominant mode of soil loss, while soil erosion by wind was only present on a relatively small area. The degree of soil erosion was classified into five severity classes: slight, light, moderate, severe, and very severe. Soil erosion in the Liupan Mountain Region increased between the late 1980s and 2000, both in terms of acreage and severity. Moderate, severe, and very severe eroded areas accounted for 54.86% of the total land area. The lightly eroded area decreased, while the moderately eroded area increased by 368817 ha (22%) followed by severe erosion with 146552 ha (8.8%), and very severe erosion by 97067.6 ha (5.8%). Soil loss on sloping cropland increased with slope gradients. About 90% of the cropland was located on slopes less than 15°. Most of the increase in soil erosion on cropland was due to conversion of steep slopes to cropland and degradation of grassland and increased activities. Soil erosion was severe on grassland with a moderate or low grass cover and on dry land. Human activities, cultivation on steep slopes, and overgrazing of pastures were the main reasons for the increase in erosion severity.

关键词： land use/land cover change soil erosion geographical information system remote sensing Liupan Mountain Region

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An Empirical Study on the Internal Control Efficiency of Listed Engineering Companies

Zhi-wen Wang,Jing Tong

《工程管理前沿（英文）》 2015年第2卷第2期页码 159-164 doi: 10.15302/J-FEM-2015026

摘要： The authors carried out an empirical study on the internal control efficiency of publically listed engineering companies in China. This study presents an exploration of the relationship of independent director ratios, audit committee quality and auditor independence with the internal control efficiency of publically listed engineering companies and forward suggestions and recommendations on raising the internal control efficiency of publically listed engineering companies.

关键词： internal control efficiency board of directors independent directors audit committee

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水轮机抗磨蚀金属材料的优化设计

王飚,张自华,王宇栋

《中国工程科学》 2000年第2卷第2期页码 64-67

摘要：

对抗磨蚀金属材料的基础研究表明，在10种常用结构材料的金属中，以钨、钴、铬的抗气蚀性最佳；生产应用研究结果表明，钨系材料中的火焰喷焊WC-M硬面陶瓷材料，铬系材料中的电镀稀土铬硬面材料，钴系材料中的等离子喷焊CoCrWC硬面材料，都是抗磨蚀性能较优，成本较低，并可进入工业应用的水轮机抗磨蚀结构材料。

关键词：水轮机磨蚀材料设计

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水机材料的抗磨蚀性判据研究

王飚,王宇栋,张自华,叶献国

《中国工程科学》 2003年第5卷第7期页码 58-61

摘要：

为了证实水机材料的抗磨蚀和抗空蚀性能与材料的常规宏观性能之间的相依关系，选取4种具代表性的材料（碳化钨涂层、NiCr合金涂层、硼不锈钢涂层和钛），进行空蚀和磨蚀试验，并测试了它们的硬度和抗腐蚀性。试验结果表明，材料的空蚀和磨蚀抗力与硬度和抗腐蚀性有着紧密的相依关系：高硬度是抗磨蚀性优的第一判据，较强的抗腐蚀性是第二判据；高抗腐蚀性是抗空蚀性优的第一判据，较高的硬度是第二判据。

关键词：水机材料磨蚀判据

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Effects of alfalfa coverage on runoff, erosion and hydraulic characteristics of overland flow on loess

Shufang WU, Pute WU, Hao FENG, G. P. Merkley

《环境科学与工程前沿（英文）》 2011年第5卷第1期页码 76-83 doi: 10.1007/s11783-011-0282-x

摘要： An evaluation of the interactions between vegetation, overland and soil erosion can provide valuable insight for the conservation of soil and water. An experiment was conducted to study water infiltration, runoff generation process, rate of sediment erosion, and hydrodynamic characteristics of overland flow from a sloping hillside with different draw-off discharges from alfalfa and control plots with 20° slope. The effect of alfalfa on runoff and sediment transport reduction was quantitatively analyzed. Alfalfa was discussed for its ability to reduce the overland flow scouring force or change the runoff movement. Compared to the bare-soil plots, alfalfa plots generated a 1.77 times increase in infiltration rate. Furthermore, the down-slope water infiltration rate for the bare soil plots was higher than in the up-slope, while the opposite was found in the alfalfa plots. In addition, alfalfa had a significant effect on runoff and sediment yield. In comparison to the control, the runoff coefficient and sediment transportation rate decreased by 28.3% and 78.4% in the grass slope, respectively. The runoff generated from the alfalfa and bare-soil plots had similar trends with an initial increase and subsequent leveling to a steady-state rate. The transport of sediment reduced with time as a consequence of the depletion of loose surface materials. The maximum sediment concentration was recorded within the first few minutes of each event. The alfalfa plots had subcritical flow while the bare-soil plots had supercritical flow, which indicate that the capability of the alfalfa slope for resisting soil erosion and sediment movement was greater than for bare soil plots. Moreover, the flow resistance coefficient and roughness coefficient for the alfalfa plots were both higher than for the bare-soil plots, which indicate that overland flow in alfalfa plots had retarded and was blocked, and the flow energy along the runoff path had gradually dissipated. Finally, the ability to erode and transport sediment had decreased.

关键词： alfalfa soil erosion runoff and sedimentation soil water infiltration overland flow hydrodynamic characteristics

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Advances in polishing of internal structures on parts made by laser-based powder bed fusion

《机械工程前沿（英文）》 2023年第18卷第1期 doi: 10.1007/s11465-022-0724-0

摘要： The internal structures of metallic products are important in realizing functional applications. Considering the manufacturing of inner structures, laser-based powder bed fusion (L-PBF) is an attractive approach because its layering principle enables the fabrication of parts with customized interior structures. However, the inferior surface quality of L-PBF components hinders its productization progress seriously. In this article, process, basic forms, and applications relevant to L-PBF internal structures are reviewed comprehensively. The causes of poor surface quality and differences in the microstructure and property of the surface features of L-PBF inner structures are presented to provide a perspective of their surface characteristics. Various polishing technologies for L-PBF components with inner structures are presented, whereas their strengths and weaknesses are summarized along with a discussion on the challenges and prospects for improving the interior surface quality of L-PBF parts.

关键词： laser-based powder bed fusion polishing internal structures surface quality surface features post process additive manufacturing

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investigation of the chemical and electrochemical characteristics of planar solid oxide fuel cell with direct internal

Yuzhang WANG, Shilie WENG, Yiwu WENG

《能源前沿（英文）》 2011年第5卷第2期页码 195-206 doi: 10.1007/s11708-011-0148-8

摘要： A fully three-dimensional mathematical model of a planar solid oxide fuel cell (SOFC) with complete direct internal steam reforming was constructed to investigate the chemical and electrochemical characteristics of the porous-electrode-supported (PES)-SOFC developed by the Central Research Institute of Electric Power Industry of Japan. The effective kinetic models developed over the Ni/YSZ anode takes into account the heat transfer and species diffusion limitations in this porous anode. The models were used to simulate the methane steam reforming processes at the co- and counter-flow patterns. The results show that the flow patterns of gas and air have certain effects on cell performance. The cell at the counter-flow has a higher output voltage and output power density at the same operating conditions. At the counter-flow, however, a high hotspot temperature is observed in the anode with a non-fixed position, even when the air inlet flow rate is increased. This is disadvantageous to the cell. Both cell voltage and power density decrease with increased air flow rate.

关键词： planar solid oxide fuel cell (SOFC) direct internal reforming chemical reaction methane electrochemical

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The cavitation erosion damage process of dynamically loaded journal bearings

MA Yan-yan, CHENG Xian-hua

《机械工程前沿（英文）》 2006年第1卷第4期页码 461-464 doi: 10.1007/s11465-006-0059-2

摘要： The cavitation damage model was built using finite element analysis software MSC.Marc. This paper attempted to numerically analyze the action process based on damage mechanics when a jet created by bubble collapse acted on the bearing surface in the process of cavitation erosion. The numerical results show that the values of equivalent plastic strain and void volume fraction increase with time. The values of damage scalar are higher on the bearing surface and subsurface, and decrease when it approaches the interface of overlay and nickel layer. The strain history and damage evolvement of bearing material acted on by jet impact load can be calculated efficiently using the proposed method, which develops a new method of analyzing cavitation erosion failure of the bearing surface.

关键词： bearing fraction increase collapse process evolvement

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enhancement and acute biotoxicity removal through the treatment of pharmaceutical wastewater using a combined internal

Liang SUN, Can WANG, Min JI, Fen WANG

《环境科学与工程前沿（英文）》 2011年第5卷第3期页码 481-487 doi: 10.1007/s11783-011-0341-3

摘要： Actual pharmaceutical wastewater was treated using a combined ultrasonic irradiation (US) and iron/coke internal electrolysis (Fe/C) technology. A significant synergetic effect was observed, showing that ultrasonic irradiation dramatically enhanced the chemical oxygen demand (COD) removal efficiencies by internal electrolysis. The effects of primary operating factors on COD removal were evaluated systematically. Higher ultrasonic frequency and lower pH values as well as longer reaction time were favorable to COD removal. The ratio of biochemical oxygen demand (BOD) and COD (B/C) of the wastewater increased from 0.21 to 0.32 after US-Fe/C treatment. An acute biotoxicity assay measuring the inhibition of bioluminescence indicated that the wastewater with overall toxicity of 4.3 mg-Zn ·L was reduced to 0.5 mg-Zn ·L after treatment. Both the raw and the treated wastewater samples were separated and identified. The types of compounds suggested that the increased biodegradability and reduced biotoxicity resulted mainly from the destruction of N,N-2 dimethyl formamide and aromatic compounds in the pharmaceutical wastewater.

关键词： internal electrolysis ultrasonic pharmaceutical wastewater biodegradability acute biotoxicity