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A three-dimensional two-level gradient smoothing meshfree method for rainfall induced landslide simulations

Dongdong WANG, Jiarui WANG, Junchao WU, Junjun DENG, Ming SUN

《结构与土木工程前沿（英文）》 2019年 第13卷 第2期   页码 337-352 doi: 10.1007/s11709-018-0467-5

摘要： A three-dimensional two-level gradient smoothing meshfree method is presented for rainfall induced landslide simulations. The two-level gradient smoothing for meshfree shape function is elaborated in the three-dimensional Lagrangian setting with detailed implementation procedure. It is shown that due to the successive gradient smoothing operation without the requirement of derivative computation in the present formulation, the two-level smoothed gradient of meshfree shape function is capable of achieving a given influence domain more efficiently than the standard gradient of meshfree shape function. Subsequently, the two-level smoothed gradient of meshfree shape function is employed to discretize the weak form of coupled rainfall seepage and soil motion equations in a nodal integration format, as provides an efficient three-dimensional regularized meshfree formulation for large deformation rainfall induced landslide simulations. The exponential damage and pressure dependent plasticity relationships are utilized to describe the failure evolution in landslides. The plastic response of soil is characterized by the true effective stress measure, which is updated according to the rotationally neutralized objective integration algorithm. The effectiveness of the present three-dimensional two-level gradient smoothing meshfree method is demonstrated through numerical examples.

关键词： meshfree method     landslide     rainfall     three-dimensional two-level gradient smoothing     nodal integration    

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Velocity gradient elasticity for nonlinear vibration of carbon nanotube resonators

Hamid M. SEDIGHI, Hassen M. OUAKAD

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1520-1530 doi: 10.1007/s11709-020-0672-x

摘要： In this study, for the first time, we investigate the nonlocality superimposed to the size effects on the nonlinear dynamics of an electrically actuated single-walled carbon-nanotube-based resonator. We undertake two models to capture the nanostructure nonlocal size effects: the strain and the velocity gradient theories. We use a reduced-order model based on the differential quadrature method (DQM) to discretize the governing nonlinear equation of motion and acquire a discretized-parameter nonlinear model of the system. The structural nonlinear behavior of the system assuming both strain and velocity gradient theories is investigated using the discretized model. The results suggest that nonlocal and size effects should not be neglected because they improve the prediction of corresponding dynamic amplitudes and, most importantly, the critical resonant frequencies of such nanoresonators. Neglecting these effects may impose a considerable source of error, which can be amended using more accurate modeling techniques.

关键词： velocity gradient elasticity theory     nanotube resonators     differential-quadrature method     nonlinear vibration    

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过渡区提取方法综述

刘锁兰,杨静宇

《中国工程科学》 2007年 第9卷 第9期   页码 89-96

摘要：

图像分割是图像理论发展的瓶颈， 过渡区是指图像中介于目标和背景之间的 特殊区域，借助于过渡区的确定进行图像 分割。主要介绍了过渡区提取的两大类方法 ：基于梯度的方法和基于非梯度的方法， 并对提取效果以及存在的问题做了简要分析。

关键词： 过渡区     提取     图像分割     梯度法     非梯度法    

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prediction and optimization design of sustainable concrete based on squirrel search algorithm-extreme gradient

《结构与土木工程前沿（英文）》   页码 1310-1325 doi: 10.1007/s11709-023-0997-3

摘要： Concrete is the most commonly used construction material. However, its production leads to high carbon dioxide (CO2) emissions and energy consumption. Therefore, developing waste-substitutable concrete components is necessary. Improving the sustainability and greenness of concrete is the focus of this research. In this regard, 899 data points were collected from existing studies where cement, slag, fly ash, superplasticizer, coarse aggregate, and fine aggregate were considered potential influential factors. The complex relationship between influential factors and concrete compressive strength makes the prediction and estimation of compressive strength difficult. Instead of the traditional compressive strength test, this study combines five novel metaheuristic algorithms with extreme gradient boosting (XGB) to predict the compressive strength of green concrete based on fly ash and blast furnace slag. The intelligent prediction models were assessed using the root mean square error (RMSE), coefficient of determination (R2), mean absolute error (MAE), and variance accounted for (VAF). The results indicated that the squirrel search algorithm-extreme gradient boosting (SSA-XGB) yielded the best overall prediction performance with R2 values of 0.9930 and 0.9576, VAF values of 99.30 and 95.79, MAE values of 0.52 and 2.50, RMSE of 1.34 and 3.31 for the training and testing sets, respectively. The remaining five prediction methods yield promising results. Therefore, the developed hybrid XGB model can be introduced as an accurate and fast technique for the performance prediction of green concrete. Finally, the developed SSA-XGB considered the effects of all the input factors on the compressive strength. The ability of the model to predict the performance of concrete with unknown proportions can play a significant role in accelerating the development and application of sustainable concrete and furthering a sustainable economy.

关键词： sustainable concrete     fly ash     slay     extreme gradient boosting technique     squirrel search algorithm     parametric analysis    

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Vibration analysis of nano-structure multilayered graphene sheets using modified strain gradient theory

Amir ALLAHBAKHSHI,Masih ALLAHBAKHSHI

《机械工程前沿（英文）》 2015年 第10卷 第2期   页码 187-197 doi: 10.1007/s11465-015-0339-9

摘要：

In this paper, for the first time, the modified strain gradient theory is used as a new size-dependent Kirchhoff micro-plate model to study the effect of interlayer van der Waals (vdW) force for the vibration analysis of multilayered graphene sheets (MLGSs). The model contains three material length scale parameters, which may effectively capture the size effect. The model can also degenerate into the modified couple stress plate model or the classical plate model, if two or all of the material length scale parameters are taken to be zero. After obtaining the governing equations based on modified strain gradient theory via principle of minimum potential energy, as only infinitesimal vibration is considered, the net pressure due to the vdW interaction is assumed to be linearly proportional to the deflection between two layers. To solve the governing equation subjected to the boundary conditions, the Fourier series is assumed for w=w(x, y). To show the accuracy of the formulations, present results in specific cases are compared with available results in literature and a good agreement can be seen. The results indicate that the present model can predict prominent natural frequency with the reduction of structural size, especially when the plate thickness is on the same order of the material length scale parameter.

关键词： graphene     van der Waals (vdW) force     modi- fied strain gradient elasticity theory     size effect parameter    

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Development of an axial-type fan with an optimization method

Chong-hyun CHO, Soo-yong CHO, Chaesil KIM,

《能源前沿（英文）》 2009年 第3卷 第4期   页码 414-422 doi: 10.1007/s11708-009-0038-5

摘要： An axial-type fan that operates at a relative total pressure of 671Pa and a static pressure of 560Pa with a flowrate of 416.6m/min is developed using an optimization technique based on the gradient method. Prior to the optimization of the fan blade, a three-dimensional axial-type fan blade is designed based on the free-vortex method along the radial direction. Twelve design variables are applied to the optimization of the rotor blade, and one design variable is selected for optimizing a stator which is located behind the rotor to support a fan-driving motor. The total and static pressure are applied to the restriction condition with the operating flowrate on the design point, and the efficiency is chosen as the response variable to be maximized. Through these procedures, an initial axial-fan blade designed by the free vortex method is modified to increase the efficiency with a satisfactory operating condition. The optimized fan is tested and compared with the performance obtained with the same class fan to figure out the optimization effect. The test results show that the optimized fan not only satisfies the restriction conditions but also operates at the same efficiency even though the tip clearance of the optimized fan is greater than 30%. The experimental and numerical tests show that this optimization method can improve the efficiency and operating pressures on axial-type fans.

关键词： axial-type fan     gradient method     free-vortex method     design variable     total pressure     static pressure     operating flowrate    

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Predicting shear strength of slender beams without reinforcement using hybrid gradient boosting trees

Thuy-Anh NGUYEN; Hai-Bang LY; Van Quan TRAN

《结构与土木工程前沿（英文）》 2022年 第16卷 第10期   页码 1267-1286 doi: 10.1007/s11709-022-0842-0

摘要： Shear failure of slender reinforced concrete beams without stirrups has surely been a complicated occurrence that has proven challenging to adequately understand. The primary purpose of this work is to develop machine learning models capable of reliably predicting the shear strength of non-shear-reinforced slender beams (SB). A database encompassing 1118 experimental findings from the relevant literature was compiled, containing eight distinct factors. Gradient Boosting (GB) technique was developed and evaluated in combination with three different optimization algorithms, namely Particle Swarm Optimization (PSO), Random Annealing Optimization (RA), and Simulated Annealing Optimization (SA). The findings suggested that GB-SA could deliver strong prediction results and effectively generalizes the connection between the input and output variables. Shap values and two-dimensional PDP analysis were then carried out. Engineers may use the findings in this work to define beam's geometrical components and material used to achieve the desired shear strength of SB without reinforcement.

关键词： slender beam     shear strength     gradient boosting     optimization algorithms    

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Gradient-based compressive image fusion

Yang CHEN,Zheng QIN

《信息与电子工程前沿（英文）》 2015年 第16卷 第3期   页码 227-237 doi: 10.1631/FITEE.1400217

摘要： We present a novel image fusion scheme based on gradient and scrambled block Hadamard ensemble (SBHE) sampling for compressive sensing imaging. First, source images are compressed by compressive sensing, to facilitate the transmission of the sensor. In the fusion phase, the image gradient is calculated to reflect the abundance of its contour information. By compositing the gradient of each image, gradient-based weights are obtained, with which compressive sensing coefficients are achieved. Finally, inverse transformation is applied to the coefficients derived from fusion, and the fused image is obtained. Information entropy (IE), Xydeas’s and Piella’s metrics are applied as non-reference objective metrics to evaluate the fusion quality in line with different fusion schemes. In addition, different image fusion application scenarios are applied to explore the scenario adaptability of the proposed scheme. Simulation results demonstrate that the gradient-based scheme has the best performance, in terms of both subjective judgment and objective metrics. Furthermore, the gradient-based fusion scheme proposed in this paper can be applied in different fusion scenarios.

关键词： Compressive sensing (CS)     Image fusion     Gradient-based image fusion     CS-based image fusion    

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Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

《结构与土木工程前沿（英文）》   页码 1326-1340 doi: 10.1007/s11709-023-0014-x

摘要： Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

关键词： strain relationship concrete    

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图引导正则最小化的随机超梯度的交替方向方法 None

Qiang LAN, Lin-bo QIAO, Yi-jie WANG

《信息与电子工程前沿（英文）》 2018年 第19卷 第6期   页码 755-762 doi: 10.1631/FITEE.1601771

摘要： 提出并比较额外梯度交替方向的几种随机变体方法，称为带拉格朗日函数（SEGL）的随机超梯度交替方向法和带增广拉格朗日函数（SEGAL）的随机超梯度交替方向法。这些方法由两个大规模凸目标函数组成，可最小化图形引导的优化问题。机器学习中一些重要应用遵循图导引优化公式等作为线性回归、逻辑回归、Lasso结构化扩展以及结构化正则化逻辑回归的原则。通过融合逻辑回归和图形引导正则化回归，在几类数据集上进行了试验。试验结果表明所提算法优于其他竞争算法，且在实际应用中，SEGAL比SEGL性能更好。

关键词： 随机优化；图形引导最小化；超梯度法；融合逻辑回归；图导向正则化逻辑回归    

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Preparation of hydrogels with uniform and gradient chemical structures using dialdehyde cellulose and

Peiwen Liu, Carsten Mai, Kai Zhang

《化学科学与工程前沿（英文）》 2018年 第12卷 第3期   页码 383-389 doi: 10.1007/s11705-018-1718-7

摘要：

Hydrogels with precisely designed structures represent promising materials with a broad application spectrum, such as for sensor, tissue engineering and biomimetic technology. However, with highly reactive compounds, the preparation of hydrogels still needs an efficient approach for desired distribution of each component within hydrogels. In addition, a method for in situ preparation of gradient hydrogels is still lacking. Herein, we report the formation of hydrogels with either uniform or gradient internal structures via a novel, simple but very efficient method by aerating ammonia gas (NH3 gas) into the solution of dialdehyde cellulose (DAC) and a diamine. As-prepared hydrogels exhibited uniform microscopic and chemical structure or gradient distribution of functional groups. Due to lots of aldehyde groups on DAC chains, functional hydrogels can be prepared by using diverse diamines. For instance, hydrogels prepared by using 1,6-hexanediamine as a cross-linker were responsive to pH values. Moreover, this controllable process of aerating NH3 gas allows the in situ formation of gradient hydrogels; for instance, by using cyanamide as a reaction counterpart, gradient hydrogels with gradient distributions of cyanide groups were prepared.

关键词： hydrogel     uniform     gradient     dialdehyde cellulose     ammonia gas     diamine    

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Effects of gradient concentration on the microstructure and electrochemical performance of LiNi

Wenming Li, Weijian Tang, Maoqin Qiu, Qiuge Zhang, Muhammad Irfan, Zeheng Yang, Weixin Zhang

《化学科学与工程前沿（英文）》 2020年 第14卷 第6期   页码 988-996 doi: 10.1007/s11705-020-1918-9

摘要： Nickel(Ni)-rich layered materials have attracted considerable interests as promising cathode materials for lithium ion batteries (LIBs) owing to their higher capacities and lower cost. Nevertheless, Mn-rich cathode materials usually suffer from poor cyclability caused by the unavoidable side-reactions between Ni ions on the surface and electrolytes. The design of gradient concentration (GC) particles with Ni-rich inside and Mn-rich outside is proved to be an efficient way to address the issue. Herein, a series of LiNi Co Mn O (LNCM622) materials with different GCs (the atomic ratio of Ni/Mn decreasing from the core to the outer layer) have been successfully synthesized via rationally designed co-precipitation process. Experimental results demonstrate that the GC of LNCM622 materials plays an important role in their microstructure and electrochemical properties. The as-prepared GC3.5 cathode material with optimal GC can provide a shorter pathway for lithium-ion diffusion and stabilize the near-surface region, and finally achieve excellent electrochemical performances, delivering a discharge capacity over 176 mAh·g at 0.2 C rate and exhibiting capacity retention up to 94% after 100 cycles at 1 C. The rationally-designed co-precipitation process for fabricating the Ni-rich layered cathode materials with gradient composition lays a solid foundation for the preparation of high-performance cathode materials for LIBs.

关键词： gradient concentration     Ni-rich     LiNi0.6Co0.2-Mn0.2O2     electrochemical performance     lithium-ion battery    

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灵活可变的运动图像的分割算法

赵彦玲,张之超,高振,张庆超

《中国工程科学》 2006年 第8卷 第5期   页码 84-87

摘要：

运动图像的分割在基于内容的视频编码及视频检索中占有重要的地位。利用运动图像帧中的时空域信息，提出了一种分割运动对象的方法。其最大的特点是灵活性，可以根据序列的实际情况来选择算法。实验证明分割效果较好并节省了处理时间。

关键词： 时空结合     运动区域     运动对象     形态梯度算子     灵活性    

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Experimental investigation on possibility of oxygen enrichment by using gradient magnetic fields

CAI Jun, WANG Li, TONG Lige, SUN Shufeng, WU Ping

《化学科学与工程前沿（英文）》 2007年 第1卷 第3期   页码 271-276 doi: 10.1007/s11705-007-0049-x

摘要： This paper presents a novel method that uses the interception effect of gradient magnetic field on oxygen molecules to realize enrichment. The use of two opposite magnetic poles of two magnets at a certain distance forms a magnetic space having a field intensity gradient near its borders. When air injected into the magnetic space outflows from the magnetic space via its borders, oxygen molecules in the air will experience the interception effect of the gradient magnetic field, but nitrogen molecules will outflow from the magnetic space without hindrance. Thus, continuous oxygen enrichment is realized. The enrichment degree of oxygen reaches 0.65% when the inlet and outlet air flows are 40 mL/min and 20 mL/min, respectively, and the gas temperature is 298 K and the maximal product of magnetic flux density and its gradient is 563 T/m (the distance between two magnetic poles is 1 mm). When the gas temperature rises to 343 K, the enrichment degree drops to 0.32%; and when the maximal product of magnetic flux density and field intensity gradient drops to 101 T/m (the distance between two magnetic poles is 4 mm), the enrichment degree drops to 0.23%. The experimental results show that there is an optimal ratio between the inlet air flow and the outlet air flow. Under the experimental conditions in this paper, the value is about 2.0. It is demonstrated that the method presented in this paper can continuously enrich oxygen and has a higher enrichment degree than other oxygen-enrichment methods using magnetic separation.
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盐度差能：现状和新趋势

Olivier Schaetzle, Cees J. N. Buisman

《工程（英文）》 2015年 第1卷 第2期   页码 164-166 doi: 10.15302/J-ENG-2015046

摘要：

在本文中，我们概述了盐度梯度技术的最新发展情况。在描述最先进盐度梯度技术的发展现状之前，我们首先介绍了盐度差能概念。本文以盐度梯度技术新兴领域中的新趋势作为结尾。

关键词： 盐度差能，压力延缓渗透，反向电渗析    

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标题 作者 时间 类型 操作

A three-dimensional two-level gradient smoothing meshfree method for rainfall induced landslide simulations

Dongdong WANG, Jiarui WANG, Junchao WU, Junjun DENG, Ming SUN

期刊论文

Velocity gradient elasticity for nonlinear vibration of carbon nanotube resonators

Hamid M. SEDIGHI, Hassen M. OUAKAD

期刊论文

过渡区提取方法综述

刘锁兰,杨静宇

期刊论文

prediction and optimization design of sustainable concrete based on squirrel search algorithm-extreme gradient

期刊论文

Vibration analysis of nano-structure multilayered graphene sheets using modified strain gradient theory

Amir ALLAHBAKHSHI,Masih ALLAHBAKHSHI

期刊论文

Development of an axial-type fan with an optimization method

Chong-hyun CHO, Soo-yong CHO, Chaesil KIM,

期刊论文

Predicting shear strength of slender beams without reinforcement using hybrid gradient boosting trees

Thuy-Anh NGUYEN; Hai-Bang LY; Van Quan TRAN

期刊论文

Gradient-based compressive image fusion

Yang CHEN,Zheng QIN

期刊论文

Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

期刊论文

图引导正则最小化的随机超梯度的交替方向方法

Qiang LAN, Lin-bo QIAO, Yi-jie WANG

期刊论文

Preparation of hydrogels with uniform and gradient chemical structures using dialdehyde cellulose and

Peiwen Liu, Carsten Mai, Kai Zhang

期刊论文

Effects of gradient concentration on the microstructure and electrochemical performance of LiNi

Wenming Li, Weijian Tang, Maoqin Qiu, Qiuge Zhang, Muhammad Irfan, Zeheng Yang, Weixin Zhang

期刊论文

灵活可变的运动图像的分割算法

赵彦玲,张之超,高振,张庆超

期刊论文

Experimental investigation on possibility of oxygen enrichment by using gradient magnetic fields

CAI Jun, WANG Li, TONG Lige, SUN Shufeng, WU Ping

期刊论文

盐度差能：现状和新趋势

Olivier Schaetzle, Cees J. N. Buisman

期刊论文