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Effect of a less permeable stronger soil layer on the stability of non-homogeneous unsaturated slopes

Nabarun DEY, Aniruddha SENGUPTA

《结构与土木工程前沿（英文）》 2020年第14卷第6期页码 1462-1475 doi: 10.1007/s11709-020-0674-8

摘要： Slope failure occurs due to an increase in the saturation level and a subsequent decrease in matric suction in unsaturated soil. This paper presents the results of a series of centrifuge experiments and numerical analyses on a 55° inclined unsaturated sandy slope with less permeable, stronger silty sand layer inclusion within it. It is observed that a less permeable, stronger silty sand layer in an otherwise homogeneous sandy soil slope hinders the infiltration of water. The water content of the slope just above the stronger layer increases significantly, compared to elsewhere. No shear band is found to initiate in a homogeneous sandy soil slope, whereas for a non-homogeneous slope, they initiate just above the less pervious, stronger layer. A discontinuity of the shear zone is also observed for the case of a non-homogeneous soil slope. The factor of safety of a non-homogeneous, unsaturated soil slope decreases because of the less permeable, stronger layer. It decreases significantly if this less permeable, stronger soil layer is located near the toe of the slope.

关键词： non-homogeneous slope stronger soil layer factor of safety centrifuge model test unsaturated soils

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施工导流工程风险的保险费用厘定方法研究

陈志鼎,胡志根

《中国工程科学》 2011年第13卷第4期页码 106-112

摘要：

在分析导流工程风险因素、综合风险率和工程保险期限的基础上，研究导流工程失效后淹没基坑造成损失的次数及其分布规律，提出导流系统失效后的总损失服从非齐次复合Poisson过程，建立基于导流工程保险损失的聚合风险模型，给出施工导流工程保险费用的厘定方法及其数学表达，为水利水电工程保险费的厘定提供理论方法。

关键词：导流风险工程保险保险费非齐次复合Poisson过程

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基于随机有限集的非齐次马尔可夫链联合概率数据关联滤波器 Research Articles

朱昀1,2,梁爽3,吴晓军1,2,杨红红1,2

《信息与电子工程前沿（英文）》 2021年第22卷第8期页码 1114-1126 doi: 10.1631/FITEE.2000209

摘要：提出一种启发式方法，通过随机有限集理论优化数据关联跟踪算法的后验密度。具体而言，提出一种改进的联合概率数据关联滤波方法，即最近邻集合联合概率数据关联方法（NNSJPDA）。为提高边缘化的准确性，利用一种基于Kullback-Leibler散度的最近邻方法，对所有可能的数据关联事件中的目标标签进行转换。此外，进一步考虑目标标签向量的分布。后验密度转换后，可得到目标标签向量的转移矩阵。该转移矩阵随时间变化，使得目标标签向量分布的传播遵循非齐次马尔可夫链。证明了该链本质上是双随机的，并推导了相应定理。通过举例和仿真，验证了所提方法的有效性。本文结果可推广到相同随机有限集框架下的其他数据关联方法。

关键词：目标跟踪；滤波理论；随机有限集理论；贝叶斯方法；马尔可夫链

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灰色斜率关联度的改进

党耀国,刘思峰,刘斌,米传民

《中国工程科学》 2004年第6卷第3期页码 41-44

摘要：

研究了单指标数据序列的几种无量纲化变换及其性质，提出了一种对灰色斜率关联度的改进模型，改进后的关联度能够反映序列的正、负相关关系，并且对原始序列进行无量纲化变换处理时不影响关联系数及关联度的值，还研究了改进的关联度及关联系数的性质。该方法充分利用了序列各时点的信息及正、负相关性，所得关联分析结果较为客观可靠，并且易于在计算机上实现。

关键词：关联度斜率无量纲化变换数据序列

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Capacity analysis for cognitive heterogeneous networks with ideal/non-ideal sensing

Tao HUANG, Ying-lei TENG, Meng-ting LIU, Jiang LIU

《信息与电子工程前沿（英文）》 2015年第16卷第1期页码 1-11 doi: 10.1631/FITEE.1400129

摘要： Due to irregular deployment of small base stations (SBSs), the interference in cognitive heterogeneous networks (CHNs) becomes even more complex; in particular, the uncertainty of spectrum mobility aggravates the interference context. In this case, how to analyze system capacity to obtain a closed-form expression becomes a crucial problem. In this paper we employ stochastic methods to formulate the capacity of CHNs and achieve a closed-form expression. By using discrete-time Markov chains (DTMCs), the spectrum mobility with respect to the arrival and departure of macro base station (MBS) users is modeled. Then an integral method is proposed to derive the interference based on stochastic geometry (SG). Also, the effect of sensing accuracy on network capacity is discussed by concerning false-alarm and miss-detection events. Simulation results are illustrated to show that the proposed capacity analysis method for CHNs can approximate the conventional sum methods without rigorous requirement for channel station information (CSI). Therefore, it turns out to be a feasible and efficient way to capture the network capacity in CHNs.

关键词： Cognitive heterogeneous networks Markov chain Stochastic geometry Homogeneous Poisson point process (HPPP)

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Control of homogeneous charge compression ignition combustion in a two-cylinder gasoline direct injection

WANG Zhi, WANG Jianxin, SHUAI Shijin, MA Qingjun, TIAN Guohong

《能源前沿（英文）》 2007年第1卷第3期页码 311-315 doi: 10.1007/s11708-007-0045-3

摘要： Homogeneous charge compression ignition (HCCI) has challenges in ignition timing control, combustion rate control, and operating range extension. In this paper, HCCI combustion was studied in a two-cylinder gasoline direct injection (GDI) engine with negative valve overlap (NVO). A two-stage gasoline direct injection strategy combined with negative valve overlap was used to control mixture formation and combustion. The gasoline engine could be operated in HCCI combustion mode at a speed range of 800–2 200 r/min and load, indicated mean effective pressure (IMEP) range of 0.1–0.53 MPa. The engine fuel consumption is below 240 g/(kW

关键词： Homogeneous control combustion consumption extension

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Bioengineering protection mechanism of city rock slope and its laboratory test

Desong JIANG, Minghua ZHAO, Chong JIANG,

《结构与土木工程前沿（英文）》 2009年第3卷第4期页码 414-421 doi: 10.1007/s11709-009-0055-9

摘要： Based on the features of rock slope bioengineering protection, the ecology protection mechanism of the urban rock slope was discussed with the mechanics effect of plants and rock slope, and the reinforcement action mechanism of rock slope by plant root system was analyzed as well. Then, the corresponding mechanical model was proposed, from which the formula to calculate the increased shearing strength of the root system-earth compound body was derived. Moreover, the side slope rainfall interception, the runoff lagging, the soil antiseepage, and the soil layer consolidating effect were studied, respectively. Furthermore, the indoor model experiment of urban crag rock slope ecology protection was designed and completed, in which various grasses to plant in slope with different angles, solid earth forms, and the different strengthening earth mechanism were studied. Finally, the present method was applied in an engineering project, from which the antiwashing behavior of three kind of grasses (i.e., the Bahiagrass, the tall fescue, and the Bermudagrass) planted in the slope with an angle of 38°, 48°, and 58°, respectively, and different strengthening structures (i.e., the diamond wire netting, the geocell and the three-dimensional network) were obtained. The application results also show that the effect of geocell structure is the best one followed by the three-dimensional net and the diamond wire net. The antiwashing capability per unit area has a critical slope angle of about 25°. The reinforcing effect of Bermudagrass is better than the Bahiagrass and tall fescue.

关键词： indoor engineering project protection mechanism different runoff lagging

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Liquid discharge plasma for fast biomass liquefaction at mild conditions: The effects of homogeneous

Sen Wang, Shiyun Liu, Danhua Mei, Rusen Zhou, Congcong Jiang, Xianhui Zhang, Zhi Fang, Kostya (Ken) Ostrikov

《化学科学与工程前沿（英文）》 2020年第14卷第5期页码 763-771 doi: 10.1007/s11705-019-1896-y

摘要： Non-thermal plasma exhibits unique advantages in biomass conversion for the sustainable production of higher-value energy carriers. Different homogeneous catalysts are usually required for plasma-enabled biomass liquefaction to achieve time-and energy-efficient conversions. However, the effects of such catalysts on the plasma-assisted liquefaction process and of the plasma on those catalysts have not been thoroughly studied. In this study, an electrical discharge plasma is employed to promote the direct liquefaction of sawdust in a mixture of polyethylene glycol 200 and glycerol. Three commonly used chemicals, sulfuric acid, nitric acid and sodium -toluene sulfate, were selected as catalysts. The effects of the type of catalyst and concentration on the liquefaction yield were examined; further, the roles of the catalysts in the plasma liquefaction process have been discussed. The results showed that the liquefaction yield attains a value of 90% within 5 min when 1% sulfuric acid was employed as the catalyst. Compared with the other catalysts, sulfuric acid presents the highest efficiency for the liquefaction of sawdust. It was observed that hydrogen ions from the catalyst were primarily responsible for the significant thermal effects on the liquefaction system and the generation of large quantities of active species; these effects directly contributed to a higher efficacy of the plasma-enabled liquefaction process.

关键词： discharge plasma biomass liquefaction catalyst homogeneous catalysts

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Efficiency of scalar and vector intensity measures for seismic slope displacements

Gang WANG

《结构与土木工程前沿（英文）》 2012年第6卷第1期页码 44-52 doi: 10.1007/s11709-012-0138-x

摘要： Ground motion intensity measures are usually used to predict the earthquake-induced displacements in earth dams, soil slopes and soil structures. In this study, the efficiency of various single ground motion intensity measures (scalar ) or a combination of them (vector ) are investigated using the PEER-NGA strong motion database and an equivalent-linear sliding-mass model. Although no single intensity measure is efficient enough for all slope conditions, the spectral acceleration at 1.5 times of the initial slope period and Arias intensity of the input motion are found to be the most efficient scalar for flexible slopes and stiff slopes respectively. Vector can incorporate different characteristics of the ground motion and thus significantly improve the efficiency over a wide range of slope conditions. Among various vector considered, the spectral accelerations at multiple spectral periods achieve high efficiency for a wide range of slope conditions. This study provides useful guidance to the development of more efficient empirical prediction models as well as the ground motion selection criteria for time domain analysis of seismic slope displacements.

关键词： seismic slope displacements intensity measures empirical prediction

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Evaluation and prediction of slope stability using machine learning approaches

《结构与土木工程前沿（英文）》 2021年第15卷第4期页码 821-833 doi: 10.1007/s11709-021-0742-8

摘要： In this paper, the machine learning (ML) model is built for slope stability evaluation and meets the high precision and rapidity requirements in slope engineering. Different ML methods for the factor of safety (FOS) prediction are studied and compared hoping to make the best use of the large variety of existing statistical and ML regression methods collected. The data set of this study includes six characteristics, namely unit weight, cohesion, internal friction angle, slope angle, slope height, and pore water pressure ratio. The whole ML model is primarily divided into data preprocessing, outlier processing, and model evaluation. In the data preprocessing, the duplicated data are first removed, then the outliers are filtered by the LocalOutlierFactor method and finally, the data are standardized. 11 ML methods are evaluated for their ability to learn the FOS based on different input parameter combinations. By analyzing the evaluation indicators R ², MAE, and MSE of these methods, SVM, GBR, and Bagging are considered to be the best regression methods. The performance and reliability of the nonlinear regression method are slightly better than that of the linear regression method. Also, the SVM-poly method is used to analyze the susceptibility of slope parameters.

关键词： slope stability factor of safety regression machine learning repeated cross-validation

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Effects of compression ratio on the combustion characteristics of a homogeneous charge compression ignition

SONG Ruizhi, ZHOU Longbao, LIU Shenghua, LI Wei, HU Tiegang

《能源前沿（英文）》 2007年第1卷第4期页码 463-467 doi: 10.1007/s11708-007-0068-0

摘要： The effects of homogeneous charge compression ignition (HCCI) engine compression ratio on its combustion characteristics were studied experimentally on a modified TY1100 single cylinder engine fueled with dimethyl ether. The resul

关键词： homogeneous cylinder combustion compression dimethyl

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砂质边坡安全保障新技术研究

牛笑笛,杨广庆,刘伟超

《中国工程科学》 2017年第19卷第6期页码 86-91 doi: 10.15302/J-SSCAE-2017.06.013

摘要：

砂质边坡稳定性差，常规防护措施的防护效果较差。为了有效地对砂质边坡进行防护，笔者研制了一种新型固砂剂——TD–1。为了验证TD–1的固砂效果，笔者进行了配比优化试验、渗透试验、干湿循环试验和现场试验。试验结果表明：在磷酸硅、硅酸锂、硅溶胶掺入比例相同的条件下，固砂试样的强度随钾水玻璃模数的增加而增大；钾水玻璃的最佳添加量为固化砂质量的3%；加入改性剂的试样，强度有明显的增长；使用低模数钾水玻璃的试样，渗透能力相对更好；随着干湿循环次数的增加，试样的强度逐渐下降，经过3次循环之后，试样的强度基本趋于稳定。TD–1固砂剂还可与客土喷播技术结合使用，进行边坡绿化防护，固化产物有利于植物生长。

关键词：砂质边坡固砂剂室内试验现场试验

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Optimal CNN-based semantic segmentation model of cutting slope images

Mansheng LIN; Shuai TENG; Gongfa CHEN; Jianbing LV; Zhongyu HAO

《结构与土木工程前沿（英文）》 2022年第16卷第4期页码 414-433 doi: 10.1007/s11709-021-0797-6

摘要： This paper utilizes three popular semantic segmentation networks, specifically DeepLab v3+, fully convolutional network (FCN), and U-Net to qualitively analyze and identify the key components of cutting slope images in complex scenes and achieve rapid image-based slope detection. The elements of cutting slope images are divided into 7 categories. In order to determine the best algorithm for pixel level classification of cutting slope images, the networks are compared from three aspects: a) different neural networks, b) different feature extractors, and c) 2 different optimization algorithms. It is found that DeepLab v3+ with Resnet18 and Sgdm performs best, FCN 32s with Sgdm takes the second, and U-Net with Adam ranks third. This paper also analyzes the segmentation strategies of the three networks in terms of feature map visualization. Results show that the contour generated by DeepLab v3+ (combined with Resnet18 and Sgdm) is closest to the ground truth, while the resulting contour of U-Net (combined with Adam) is closest to the input images.

关键词： slope damage image recognition semantic segmentation feature map visualizations

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On the seismic stability analysis of reinforced rock slope and optimization of prestressed cables

Wenbo ZHENG, Xiaoying ZHUANG, Yongchang CAI

《结构与土木工程前沿（英文）》 2012年第6卷第2期页码 132-146 doi: 10.1007/s11709-012-0152-z

摘要： The evaluation of the seismic stability of high rock slopes is of vital importance to ensure the safe operation of the hydropower stations. In this paper, an equivalent pseudo-static force analysis based on the finite element method is developed to evaluate the seismic stability of reinforced rock slopes where the prestressed cables are modeled by the bar elements applied with nodal forces and bounded only at the anchored parts. The method is applied to analyze a high rock slope in south-west China and the optimization of cables. The stabilization effects of prestressed cables on the seismic stability of the slope are studied, the simulations of the concrete heading are discussed and the potential failure modes of the shear concrete plug are compared. Based on this, the optimization of cables is studied including the anchor spacing and inclined angles.

关键词： high rock slope reinforced system optimization prestressed cable seismicity

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Surficial stability analysis of soil slope under seepage based on a novel failure mode

《结构与土木工程前沿（英文）》 2021年第15卷第3期页码 712-726 doi: 10.1007/s11709-021-0729-5

摘要： Normally, the edge effects of surficial landslides are not considered in the infinite slope method for surficial stability analysis of soil slopes. In this study, the limit stress state and discrimination equation of an infinite slope under saturated seepage flow were analyzed based on the Mohr-Coulomb strength criterion. Therefore, a novel failure mode involving three sliding zones (upper tension zone, middle shear sliding zone, and lower compression zone) was proposed. Accordingly, based on the limit equilibrium analysis, a semi-analytical framework considering the edge effect for the surficial stability of a soil slope under downslope seepage was established. Subsequently, the new failure mode was verified via a numerical finite element analysis based on the reduced strength theory with ABAQUS and some simplified methods using SLIDE software. The results obtained by the new failure mode agree well with those obtained by the numerical analysis and traditional simplified methods, and can be efficiently used to assess the surficial stability of soil slopes under rainwater seepage. Finally, an evaluation of the infinite slope method was performed using the semi-analytical method proposed in this study. The results show that the infinite slope tends to be conservative because the edge effect is neglected, particularly when the ratio of surficial slope length to depth is relatively small.

关键词： soil slope seepage surficial failure mode stress state edge effects