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Driving mechanism and boundary control of urban sprawl

Dongmei JIANG,Xiaoshun LI,Futian QU,Mingyan LI,Shaoliang ZHANG,Yunlong GONG,Xiaoping SHI,Xin CHEN

《环境科学与工程前沿（英文）》 2015年 第9卷 第2期   页码 298-309 doi: 10.1007/s11783-014-0639-z

摘要： Since the reform and opening-up, China’s economy has achieved remarkable development and so does the urbanization. However, there is an unavoidable contradiction between urban sprawl and the protection of arable land and the environment. By redefining the urban sprawl boundary, this paper is to provide a solution for the conflict above on the China’s urbanization context. The ideal boundary, moderate boundary and limit boundary are defined for urban sprawl in space. Taking Nanjing city as a case, the three urban sprawl boundaries are estimated in this paper based on the calculation of agricultural land resources value in Nanjing. The results show that 1) the integrated value of agricultural (cultivated) land resources in Nanjing is 1.55 × 10 CNY·hm , the economic value accounts for only 8.74% of the integrated value, while 91.26% of the integrated value has not revealed itself due to the existing institutional arrangements, policy distortions, and imperfect land market; 2) it is difficult to define the ideal and moderate boundaries due to the relatively low price of North Nanjing. In South Nanjing the land price is expensive and the ideal, moderate and limit boundaries are expanded to Jiangning, Qixia, and Yuhuatai; 3) the city scale of South Nanjing should be limited within 5.82 × 10 hm , which is roughly the same as the designated size of 5.81 × 10 hm in the urban planning. It is suggested that the rational scope of urban expansion should be controlled within the moderate boundary.

关键词： urban sprawl     rational expansion     driving forces     boundary control     Nanjing    

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Numerical study and control method of interaction of nucleation and boundary layer separation in condensing

Liansuo AN , Zhi WANG , Zhonghe HAN ,

《能源前沿（英文）》 2009年 第3卷 第3期   页码 254-261 doi: 10.1007/s11708-009-0047-4

摘要： The spontaneous nucleation flow in turbine cascade was numerically studied. The model was implemented within a full Navier–Stokes viscous flow solution procedure and the process of condensation was calculated by the quadrature method of moments that shows good accuracy with very broad size distributions. Results were presented for viscous and inviscous flow, showing the influence of boundary layer separation and wake vortices on spontaneous nucleation. The results show that the degree of flow separation in wet steam flow is greater than that in superheated steam flow due to condensation shock and that the loss cannot be neglected. Furthermore, the impact of boundary layer separation and wake vortices on velocity profiles and its implications for profile loss were considered. The calculations showed that layer separation and wake vortices influence nucleation rate, leading to different droplet distributions. A method for controlling homogeneous nucleation and for reducing degree of flow separation in high-speed transonic wet steam flow was presented. The liquid phase parameter distribution is sensitive to the suction side profile of turbine cascade, which impacts the nucleation rate distribution leading to different droplet distributions and affects the degree of flow separation. The numerical study provides a practical design method for turbine blade to reduce wetness losses.

关键词： wet steam     two-phase flow     spontaneous condensation     numerical simulation     flow separation     profile loss    

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Chemically reactive solute transfer in a boundary layer slip flow along a stretching cylinder

Swati Mukhopadhyay

《化学科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 385-391 doi: 10.1007/s11705-011-1101-4

摘要： This paper presents the distribution of a solute undergoing a first order chemical reaction in an axisymmetric laminar boundary layer flow along a stretching cylinder. Velocity slip condition at the boundary is used instead of no-slip condition. Similarity transformations are used to convert the partial differential equations corresponding to momentum and concentration into highly nonlinear ordinary differential equations. Numerical solutions of these equations are obtained by the shooting method. The velocity decreases with increasing slip parameter. The skin friction as well as the mass transfer rate at the surface is larger for a cylinder than for a flat plate.

关键词： boundary layer     stretching cylinder     partial slip     mass transfer     similarity solution    

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Controlling nested wrinkle morphology through the boundary effect on narrow-band thin films

Hanyang XU, Tielin SHI, Guanglan LIAO, Qi XIA

《机械工程前沿（英文）》 2019年 第14卷 第2期   页码 235-240 doi: 10.1007/s11465-017-0458-6

摘要： We describe the formation of nested wrinkles created by the thermal mismatch between a narrow-band thin film and a compliant substrate. When a film is described as “narrow-band”, it literally means that the film band width is much shorter than its length; more precisely, it means that the width is comparable with the wavelength of the wrinkles. A silicon mask was used during film sputtering to create narrow-band films on poly (dimethylsiloxane) substrate, thus creating regular boundaries to steer local stresses and control wrinkle morphology. Disordered nano-scale wrinkles were found nested within highly ordered micro-scale sinusoidal wrinkles. The formation of nested wrinkles was explained through the amplitude and wavelength saturation of nano-scale wrinkles. The disordered morphology of nano-scale wrinkles and the highly ordered morphology of micro-scale wrinkles were explained by using the boundary effect.

关键词： nested and hierarchical wrinkles     morphology     amplitude saturation     boundary effect    

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输出受限的柔性海洋立管自适应神经网络边界控制 Research Article

余初阳1,楼旭阳1,马艺飞1,叶倩2,张今旗3

《信息与电子工程前沿（英文）》 2022年 第23卷 第8期   页码 1229-1238 doi: 10.1631/FITEE.2100586

摘要： 针对具有未知非线性扰动和输出限制的柔性海洋立管系统，提出一种基于自适应神经网络的边界控制方法抑制振动。首先，通过偏微分方程分布参数系统描述柔性海洋立管系统的动态特性。为补偿非线性扰动对系统影响，利用径向基神经网络构造一个基于神经网络的边界控制器以减少振动。在所提边界控制器下，基于李亚普诺夫方法，保证柔性海洋立管系统一致有界。该方法为其他柔性机器人系统的边界控制提供了一种集成神经网络的思路。最后，通过数值仿真验证所提方法的有效性。

关键词： 海洋立管系统；偏微分方程；神经网络；输出限制；边界控制；未知扰动    

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Approaching the upper boundary of driver-response relationships: identifying factors using a novel framework

《环境科学与工程前沿（英文）》 2023年 第17卷 第6期 doi: 10.1007/s11783-023-1676-2

摘要：

● A novel framework integrating quantile regression with machine learning is proposed.

关键词： Driver-response     Upper boundary of relationship     Interpretable machine learning     Quantile regression     Total phosphorus     Chlorophyll a    

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Comparison of indirect boundary element and finite element methods A case study: Shiraz-Esfahan railway

Amin MANOUCHEHRIAN, Mohammad Fatehi MARJI, Mohsen MOHEBBI

《结构与土木工程前沿（英文）》 2012年 第6卷 第4期   页码 385-392 doi: 10.1007/s11709-012-0173-7

摘要： Because of the high importance of transportation tunnels, most precise analyses of stress concentration and displacement around them are essential to provide safety of them as much as possible. Recently, various numerical methods such as finite element method (FEM), discrete element method (DEM), finite difference method (FDM) and boundary element method (BEM) have been used extremely in geosciences problems, but among these numerical methods, BEM has been used less than others because the computational algorithm is not so straightforward. This paper suggests the implementation of the indirect boundary element method (IBEM) as a formulation of BEM to analyze displacement around Shiraz-Esfahan railway tunnel in Zagros Mountains southwest of Iran. For this purpose, this tunnel has been modeled numerically using two-dimensional fictitious stress method (TWOFS) algorithm. To validate the results, they were compared with FEM results as a commonly used numerical method. Results of current theoretical study have shown that the presented approach using IBEM is reasonably accurate and can be used for analysis of displacement in geosciences problems. In rock mechanics, for problems with a low ratio of boundary surface to volume, FEM is not very well suited and may be cumbersome, but use of such a proposed IBEM approach can be particularly attractive.

关键词： indirect boundary element method     finite element method     displacement     tunnel     case study    

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Engineering the grain boundary: a promising strategy to configure NiCoPO/NiCoP nanowire arrays for ultra-stable

《化学科学与工程前沿（英文）》 2022年 第16卷 第8期   页码 1259-1267 doi: 10.1007/s11705-021-2132-0

摘要： NiCoP4O12/NiCoP nanorod-like arrays with tunable grain boundary density and pores were synthesized by the processes composed of hydrothermal and pyrolysis, in which, the electron structure of Ni and Co atoms characterized by X-ray photoelectron spectroscopy was contemporaneous inverse manipulated. The optimized NiCoP4O12/NiCoP arrays have a high specific capacitance of 507.8 μAh∙cm–2 at 1 mA∙cm–2, and good rate ability of 64.7% retention at 30-folds increased current density. Importantly, an ultra-stable ability, 88.5% of retention after 10000 cycles, was achieved in an asymmetric cell assembled of the NiCoP4O12/NiCoP arrays with activated carbon. In addition, the energy and power densities of an asymmetric cell were higher than those of other work, demonstrating as-prepared NiCoP4O12/NiCoP arrays are promising electrodes for supercapacitors.

关键词： NiCo     array electrode     grain boundary     stability     supercapacitor    

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Slender reinforced concrete shear walls with high-strength concrete boundary elements

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 138-151 doi: 10.1007/s11709-022-0897-y

摘要： Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

关键词： slender walls     high-strength concrete     rectangular and barbell-shaped walls     cold joints    

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Hydrologic experiments and modeling of two laboratory bioretention systems under different boundary conditions

Ruifen Liu, Elizabeth Fassman-Beck

《环境科学与工程前沿（英文）》 2017年 第11卷 第4期 doi: 10.1007/s11783-017-0951-5

摘要： Hydrologic performance of bioretention systems is significantly influenced by the media composition and underdrain configuration. This research measured hydrologic performance of column-scale bioretention systems during a synthetic design storm of 25.9 mm, assuming a system area:catchment area ratio of 5%. The laboratory experiments involved two different engineered media and two different drainage configurations. Results show that the two engineered media with different sand aggregates were able to retain about 36% of the inflow volume with free drainage configuration. However, the medium with marine sand is better at delaying the occurrence of drainage than the one with pumice sand, denoting the better detention ability of the former. For both engineered media, an underdrain configuration with internal water storage (IWS) zone lowered drainage volume and peak drainage rate as well as delayed the occurrence of drainage and peak drainage rate, as compared to a free drainage configuration. The USEPA SWMM v5.1.11 model was applied for the free drainage configuration case, and there is a reasonable fit between observed and modeled drainage-rates when media-specific characteristics are available. For the IWS drainage configuration case, air entrapment was observed to occur in the engineered medium with marine sand. Filling of an IWS zone is most likely to be influenced by many factors, such as the structure of the bioretention system, medium physical and hydraulic properties, and inflow characteristics. More research is needed on the analysis and modeling of hydrologic process in bioretention with IWS drainage configuration.

关键词： Bioretention     Hydrologic process     Underdrain configuration     SWMM     Modeling    

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Influence of boundary conditions and turntable speeds on the stability of hydrostatic oil cavity

Zhaomiao LIU, Chengyin ZHANG, Feng SHEN

《机械工程前沿（英文）》 2011年 第6卷 第3期   页码 359-368 doi: 10.1007/s11465-011-0222-2

摘要：

The flow, bearing, and carrying capacity of the cycloidal hydrostatic oil cavity in hydrostatic turntable systems are numerically simulated, considering the rotation speeds of a turntable from 0 to 5 m/s and different boundary conditions. The vortex effect is weakened, and the stability of the oil cavity is enhanced with the increase in lubricant viscosity. However, the increase in inlet speed, depth, and inlet radius of the oil cavity causes the vortex effect to increase and the stability of oil cavity to reduce. With the increase in the oil film thickness, the carrying capacity of the oil cavity diminishes. The oil cavity pressure increases along the direction of the motion of the turntable; it is distributed unevenly because of the rotation of the turntable. With the increase in turntable speed, the location and size of the vortex scope in the oil cavity flow field and the strength of the vortex near the entrance gradually weaken and move away from the entry. The distribution of pressure is determined by the locations of the vortex. When the vortex is close to the wall, the wall pressure increases at its location. Otherwise, the wall pressure decreases first and then increases after the center of the vortex.

关键词： hydrostatic oil cavity     flow state     oil cavity pressure     stability     vortex    

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Implementation of sinh method in integration space for boundary integrals with near singularity in potential

Guizhong XIE,Dehai ZHANG,Jianming ZHANG,Fannian MENG,Wenliao DU,Xiaoyu WEN

《机械工程前沿（英文）》 2016年 第11卷 第4期   页码 412-422 doi: 10.1007/s11465-016-0396-8

摘要：

As a widely used numerical method, boundary element method (BEM) is efficient for computer aided engineering (CAE). However, boundary integrals with near singularity need to be calculated accurately and efficiently to implement BEM for CAE analysis on thin bodies successfully. In this paper, the distance in the denominator of the fundamental solution is first designed as an equivalent form using approximate expansion and the original sinh method can be revised into a new form considering the minimum distance and the approximate expansion. Second, the acquisition of the projection point by Newton-Raphson method is introduced. We acquire the nearest point between the source point and element edge by solving a cubic equation if the location of the projection point is outside the element, where boundary integrals with near singularity appear. Finally, the subtriangles of the local coordinate space are mapped into the integration space and the sinh method is applied in the integration space. The revised sinh method can be directly performed in the integration element. A verification test of our method is proposed. Results demonstrate that our method is effective for regularizing the boundary integrals with near singularity.

关键词： computer aided engineering (CAE)     boundary element method (BEM)     near singularity     sinh method     coordinate transformation     integration space    

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A new meshless approach for bending analysis of thin plates with arbitrary shapes and boundary conditions

《结构与土木工程前沿（英文）》 2022年 第16卷 第1期   页码 75-85 doi: 10.1007/s11709-021-0798-5

摘要： An efficient and meshfree approach is proposed for the bending analysis of thin plates. The approach is based on the choice of a set of interior points, for each of which a basis function can be defined. Plate deflection is then approximated as the linear combination of those basis functions. Unlike traditional meshless methods, present basis functions are defined in the whole domain and satisfy the governing differential equation for plate. Therefore, no domain integration is needed, while the unknown coefficients of deflection expression could be determined through boundary conditions by using a collocation point method. Both efficiency and accuracy of the approach are shown through numerical results of plates with arbitrary shapes and boundary conditions under various loads.

关键词： plate     bending     meshless method     collocation    

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A way to explain the thermal boundary effects on laminar convection through a square duct

Liangbi WANG, Xiaoping GAI, Kun HUANG, Yongheng ZHANG, Xiang YANG, Xiang WU

《能源前沿（英文）》 2010年 第4卷 第4期   页码 496-506 doi: 10.1007/s11708-010-0020-2

摘要： A way using the reformulation of the energy conservation equation in terms of heat flux to explain the thermal boundary effects on laminar convective heat transfer through a square duct is presented. For a laminar convection through a square duct, it explains that on the wall surface, the velocity is zero, but convection occurs for uniform wall heat flux (UWHF) boundary in the developing region due to the velocity gradient term; for uniform wall temperature (UWT) boundary, only diffusion process occurs on the wall surface because both velocity and velocity gradient do not contribute to convection; for UWHF, the largest term of the gradient of velocity components (the main flow velocity) on the wall surface takes a role in the convection of the heat flux normal to the wall surface, and this role exists in the fully developed region. Therefore, a stronger convection process occurs for UWHF than for UWT on the wall surface. The thermal boundary effects on the laminar convection inside the flow are also detailed.

关键词： convective transport     heat transfer     mass transfer     laminar flow     thermal boundary effects    

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基于最小二乘法的EAST托卡马克光学等离子体边缘重建 None

Hao LUO, Zheng-ping LUO, Chao XU, Wei JIANG

《信息与电子工程前沿（英文）》 2018年 第19卷 第9期   页码 1124-1134 doi: 10.1631/FITEE.1700041

摘要： 重建等离子体位形是托卡马克装置中一个非常重要的课题。平衡与反演编码（equilibrium and fitting, EFIT）是部分托卡马克中常用的等离子体边缘重建方法。然而，这种磁方法有一些不可避免的缺点。提出一种光学等离子体边缘重建算法，将EFIT编码结果作为标准值学习光学重建模型。在边缘提取方面，传统边缘检测方法不能提取较清晰的等离子体边缘。因此，提出一种基于全局对比度的方法在图像平面提取等离子体边缘。这种方法对光照有很好的鲁棒性。用一个同阶多项式和一个转换矩阵拟合提取等离子体边缘和EFIT重建等离子体边缘。为在没有相机标定的前提下获取转换矩阵，用最小二乘法最小化光学边缘和EFIT重建边缘误差，得到一个数学模型，该数学模型将提取的等离子体边缘从一个图像平面转换到托卡马克极向平面。一旦获得这个转换矩阵，便可在捕获的任意图像重建光学等离子体边缘。展示了所提方法和EFIT之间的误差，并讨论不同多项式阶数的实验结果。

关键词： 光学等离子体重建；边缘检测；全局对比度；最小二乘法；EAST托卡马克    

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标题 作者 时间 类型 操作

Driving mechanism and boundary control of urban sprawl

Dongmei JIANG,Xiaoshun LI,Futian QU,Mingyan LI,Shaoliang ZHANG,Yunlong GONG,Xiaoping SHI,Xin CHEN

期刊论文

Numerical study and control method of interaction of nucleation and boundary layer separation in condensing

Liansuo AN , Zhi WANG , Zhonghe HAN ,

期刊论文

Chemically reactive solute transfer in a boundary layer slip flow along a stretching cylinder

Swati Mukhopadhyay

期刊论文

Controlling nested wrinkle morphology through the boundary effect on narrow-band thin films

Hanyang XU, Tielin SHI, Guanglan LIAO, Qi XIA

期刊论文

输出受限的柔性海洋立管自适应神经网络边界控制

余初阳1,楼旭阳1,马艺飞1,叶倩2,张今旗3

期刊论文

Approaching the upper boundary of driver-response relationships: identifying factors using a novel framework

期刊论文

Comparison of indirect boundary element and finite element methods A case study: Shiraz-Esfahan railway

Amin MANOUCHEHRIAN, Mohammad Fatehi MARJI, Mohsen MOHEBBI

期刊论文

Engineering the grain boundary: a promising strategy to configure NiCoPO/NiCoP nanowire arrays for ultra-stable

期刊论文

Slender reinforced concrete shear walls with high-strength concrete boundary elements

期刊论文

Hydrologic experiments and modeling of two laboratory bioretention systems under different boundary conditions

Ruifen Liu, Elizabeth Fassman-Beck

期刊论文

Influence of boundary conditions and turntable speeds on the stability of hydrostatic oil cavity

Zhaomiao LIU, Chengyin ZHANG, Feng SHEN

期刊论文

Implementation of sinh method in integration space for boundary integrals with near singularity in potential

Guizhong XIE,Dehai ZHANG,Jianming ZHANG,Fannian MENG,Wenliao DU,Xiaoyu WEN

期刊论文

A new meshless approach for bending analysis of thin plates with arbitrary shapes and boundary conditions

期刊论文

A way to explain the thermal boundary effects on laminar convection through a square duct

Liangbi WANG, Xiaoping GAI, Kun HUANG, Yongheng ZHANG, Xiang YANG, Xiang WU

期刊论文

基于最小二乘法的EAST托卡马克光学等离子体边缘重建

Hao LUO, Zheng-ping LUO, Chao XU, Wei JIANG

期刊论文