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Uncertainty of concrete strength in shear and flexural behavior of beams using lattice modeling

《结构与土木工程前沿（英文）》 2023年第17卷第2期页码 306-325 doi: 10.1007/s11709-022-0890-5

摘要： This paper numerically studied the effect of uncertainty and random distribution of concrete strength in beams failing in shear and flexure using lattice modeling, which is suitable for statistical analysis. The independent variables of this study included the level of strength reduction and the number of members with reduced strength. Three levels of material deficiency (i.e., 10%, 20%, 30%) were randomly introduced to 5%, 10%, 15%, and 20% of members. To provide a database and reliable results, 1000 analyses were carried out (a total of 24000 analyses) using the MATLAB software for each combination. Comparative studies were conducted for both shear- and flexure-deficit beams under four-point loading and results were compared using finite element software where relevant. Capability of lattice modeling was highlighted as an efficient tool to account for uncertainty in statistical studies. Results showed that the number of deficient members had a more significant effect on beam capacity compared to the level of strength deficiency. The scatter of random load-capacities was higher in flexure (range: 0.680–0.990) than that of shear (range: 0.795–0.996). Finally, nonlinear regression relationships were established with coefficient of correlation values (R²) above 0.90, which captured the overall load–deflection response and level of load reduction.

关键词： lattice modeling shear failure flexural failure uncertainty deficiency numerical simulation

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Modeling nanostructured catalyst layer in PEMFC and catalyst utilization

Jiejing ZHANG, Pengzhen CAO, Li XU, Yuxin WANG

《化学科学与工程前沿（英文）》 2011年第5卷第3期页码 297-302 doi: 10.1007/s11705-011-1201-1

摘要： A lattice model of the nanoscaled catalyst layer structure in proton exchange membrane fuel cells (PEMFC) was established by Monte Carlo method. The model takes into account all the four components in a typical PEMFC catalyst layer: platinum (Pt), carbon, ionomer and pore. The elemental voxels in the lattice were set fine enough so that each average sized Pt particulate in Pt/C catalyst can be represented. Catalyst utilization in the modeled catalyst layer was calculated by counting up the number of facets of Pt voxels where “three phase contact” are met. The effects of some factors, including porosity, ionomer content, Pt/C particle size and Pt weight percentage in the Pt/C catalyst, on catalyst utilization were investigated and discussed.

关键词： catalyst layer PEM fuel cell lattice model Monte Carlo method catalyst utilization

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Compressive behavior and energy absorption of polymeric lattice structures made by additive manufacturing

Sheng WANG, Jun WANG, Yingjie XU, Weihong ZHANG, Jihong ZHU

《机械工程前沿（英文）》 2020年第15卷第2期页码 319-327 doi: 10.1007/s11465-019-0549-7

摘要： Lattice structures have numerous outstanding characteristics, such as light weight, high strength, excellent shock resistance, and highly efficient heat dissipation. In this work, by combining experimental and numerical methods, we investigate the compressive behavior and energy absorption of lattices made through the stereolithography apparatus process. Four types of lattice structures are considered: (i) Uniform body-centered-cubic (U-BCC); (ii) graded body-centered-cubic (G-BCC); (iii) uniform body-centered-cubic with -axis reinforcement (U-BCCz); and (iv) graded body-centered-cubic with -axis reinforcement (G-BCCz). We conduct compressive tests on these four lattices and numerically simulate the compression process through the finite element method. Analysis results show that BCCz has higher modulus and strength than BCC. In addition, uniform lattices show better energy absorption capabilities at small compression distances, while graded lattices absorb more energy at large compression distances. The good correlation between the simulation results and the experimental phenomena demonstrates the validity and accuracy of the present investigation method.

关键词： lattice structure polymer compressive behavior additive manufacturing simulation

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Simulation of interfacial Marangoni convection in gas-liquid mass transfer by lattice Boltzmann method

Shuyong CHEN, Xigang YUAN, Bo FU, Kuotsung YU

《化学科学与工程前沿（英文）》 2011年第5卷第4期页码 448-454 doi: 10.1007/s11705-011-1142-8

摘要： Interfacial Marangoni convection has significant effect on gas-liquid and/or liquid-liquid mass transfer processes. In this paper, an approach based on lattice Boltzmann method is established and two perturbation models, fixed perturbation model and self-renewable interface model, are proposed for the simulation of interfacial Marangoni convection in gas-liquid mass transfer process. The simulation results show that the concentration contours are well consistent with the typical roll cell convection patterns obtained experimentally in previous studies.

关键词： interfacial Marangoni convection lattice Boltzmann method gas-liquid mass transfer

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slip investigation based on finite element modelling verified by experimental results on wind turbine lattice

Saleh YAGHOOBI, Ahmad SHOOSHTARI

《结构与土木工程前沿（英文）》 2018年第12卷第3期页码 341-351 doi: 10.1007/s11709-017-0393-y

摘要：

Slippage corresponds to the relative displacement of a bolted joint subjected to shear loads since the construction clearance between the bolt shank and the bolthole at assembly can cause joint slip. Deflections of towers with joint slippage effects is up to 1.9 times greater than the displacements obtained by linear analytical methods. In this study, 8 different types of joints are modelled and studied in the finite element program, and the results are verified by the experimental results which have been done in the laboratory. Moreover, several types of joints have been modelled and studied and load-deformation curves have also been presented. Finally, joint slip data for different types of angles, bolt diameter and bolt arrangements are generated. Thereupon, damping ratios (z) for different types of connections are reported. The study can be useful to help in designing of wind turbine towers with a higher level of accuracy and safety.

关键词： Joint slip cyclic loading Finite element modelling Experimental joint behavior damping ratios (

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URANS simulation of the turbulent flow in tight lattice bundle

Yiqi YU, Yanhua YANG

《能源前沿（英文）》 2011年第5卷第4期页码 404-411 doi: 10.1007/s11708-011-0165-7

摘要： The flow structure in tight lattice is still of great interest to nuclear industry. An accurate prediction of flow parameter in subchannels of tight lattice is likable. Unsteady Reynolds averaged Navier Stokes (URANS) is a promising approach to achieve this goal. The implementation of URANS approach will be validated by comparing computational results with the experimental data of Krauss. In this paper, the turbulent flow with different Reynolds number (5000–215000) and different pitch-to-diameter( / ) (1.005–1.2) are simulated with computational fluid dynamics (CFD) code CFX12. The effects of the Reynolds number and the bundle geometry ( / ) on wall shear stress, turbulent kinetic energy, turbulent mixing and large scale coherent structure in tight lattice are analyzed in details. It is hoped that the present work will contribute to the understanding of these important flow phenomena and facilitate the prediction and design of rod bundles.

关键词： tight rod bundle flow structure unsteady Reynolds averaged Navier Stokes (URANS)

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Robust topology optimization of multi-material lattice structures under material and load uncertainties

Yu-Chin CHAN, Kohei SHINTANI, Wei CHEN

《机械工程前沿（英文）》 2019年第14卷第2期页码 141-152 doi: 10.1007/s11465-019-0531-4

摘要： Enabled by advancements in multi-material additive manufacturing, lightweight lattice structures consisting of networks of periodic unit cells have gained popularity due to their extraordinary performance and wide array of functions. This work proposes a density-based robust topology optimization method for meso- or macro-scale multi-material lattice structures under any combination of material and load uncertainties. The method utilizes a new generalized material interpolation scheme for an arbitrary number of materials, and employs univariate dimension reduction and Gauss-type quadrature to quantify and propagate uncertainty. By formulating the objective function as a weighted sum of the mean and standard deviation of compliance, the tradeoff between optimality and robustness can be studied and controlled. Examples of a cantilever beam lattice structure under various material and load uncertainty cases exhibit the efficiency and flexibility of the approach. The accuracy of univariate dimension reduction is validated by comparing the results to the Monte Carlo approach.

关键词： robust topology optimization lattice structures multi-material material uncertainty load uncertainty univariate dimension reduction

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超轻折叠夹层圆柱壳的制备及力学性能测试 Article

李万欣, 郑青, 范华林, 冀宾

《工程（英文）》 2020年第6卷第2期页码 196-204 doi: 10.1016/j.eng.2019.11.008

摘要：

在本研究中，我们设计、制备和测试了两种新型折叠夹层圆柱壳。格栅夹芯具有周期性的“之”字形波纹，其脊线与谷线沿着轴向或环向延伸。通过自由振动和轴向压缩试验，我们研究了圆柱壳的固有频率、自由振动模态、承载能力和失效模式。通过减小局部蒙皮周期单元的尺寸，折叠格栅夹芯能有效地抑制折叠夹层圆柱壳的局部屈曲；通过提高夹层的剪切刚度，折叠格栅夹芯能有效地提高折叠夹层圆柱壳整体的抗屈曲性能。圆柱壳在材料失效模式下失效，其具有良好的承载能力。轴向折叠夹层圆柱壳具有更高的承载能力，而环向折叠夹层圆柱壳具有更高的固有频率。这两种折叠格栅内芯为工程师设计有强度或振动要求的夹层圆柱壳提供了一种选择。本研究也为大尺寸折叠结构的制作和工程应用提供了一种可行的方法。

关键词：折叠夹层圆柱壳制备力学试验

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Soil arching effect of Lattice-Shaped Diaphragm Wall as bridge foundation

Jiujiang WU, Lingjuan WANG, Qiangong CHENG

《结构与土木工程前沿（英文）》 2017年第11卷第4期页码 446-454 doi: 10.1007/s11709-017-0397-7

摘要： As a new type of bridge foundation, Lattice-Shaped Diaphragm Wall (hereinafter for LSDW) is highly concerned in relevant construction area but its research is far from achievement. Based on PFC , the soil arching effect of LSDWs is studied thoroughly in this paper and the special attention is given to its influencing factors. It turns out to be that a differential wall-soil settlement can be found at the lower location of soil core of an LSDW which is one of the trigger factors of soil arching; meanwhile, the differential settlement degree can reflect the exertion degree of soil arching; the shape of soil arching is basically a hemisphere which can be explained by the theory proposed by Hewlett and Randolph; normally, the chamber number is a negative factor for the development of soil arching; the soil arching effect is significantly influenced by the distance of two adjacent wall elements and the foundation depth, and a relatively large or small value of these factors is disadvantageous to the exertion of soil arching; in addition, the soil arching effect increase with the growth of stiffness and friction coefficient of particles and the friction coefficient of particles has insignificant influence on the development of soil arching effect compared with particle stiffness.

关键词： LSDW soil arching PFC^2D shape of soil arching influencing factors

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Design and applications of morphing aircraft and their structures

《机械工程前沿（英文）》 2023年第18卷第3期 doi: 10.1007/s11465-023-0750-6

摘要： Morphing aircraft can adaptively regulate their aerodynamic layout to meet the demands of varying flight conditions, improve their aerodynamic efficiency, and reduce their energy consumption. The design and fabrication of high-performance, lightweight, and intelligent morphing structures have become a hot topic in advanced aircraft design. This paper discusses morphing aircraft development history, structural characteristics, existing applications, and future prospects. First, some conventional mechanical morphing aircraft are examined with focus on their morphing modes, mechanisms, advantages, and disadvantages. Second, the novel applications of several technologies for morphing unmanned aerial vehicles, including additive manufacturing for fabricating complex morphing structures, lattice technology for reducing structural weight, and multi-mode morphing combined with flexible skins and foldable structures, are summarized and categorized. Moreover, in consideration of the further development of active morphing aircraft, the paper reviews morphing structures driven by smart material actuators, such as shape memory alloy and macro-fiber composites, and analyzes their advantages and limitations. Third, the paper discusses multiple challenges, including flexible structures, flexible skins, and control systems, in the design of future morphing aircraft. Lastly, the development and application of morphing structures in the aerospace field are discussed to provide a reference for future research and engineering applications.

关键词： morphing aircraft additive manufacturing lattice structure smart material flexible structure flexible skin

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♮-convexity and its applications in operations

Xin CHEN

《工程管理前沿（英文）》 2017年第4卷第3期页码 283-294 doi: 10.15302/J-FEM-2017057

摘要： -convexity, one of the central concepts in discrete convex analysis, receives significant attentions in the operations literature in recent years as it provides a powerful tool to derive structures of optimal policies and allows for efficient computational procedures. In this paper, we present a survey of key properties of -convexity and some closely related results in lattice programming, several of which were developed recently and motivated by operations applications. As a new contribution to the literature, we establish the relationship between a notion called -differential monotonicity and -convexity. We then illustrate the techniques of applying -convexity through a detailed analysis of a perishable inventory model and a joint inventory and transshipment control model with random capacities.

关键词： L^&natur -convexity lattice programming perishable inventory models random capacity

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可移动光学晶格时钟让时间变得更精确

Dana Mackenzie

《工程（英文）》 2020年第6卷第11期页码 1210-1211 doi: 10.1016/j.eng.2020.08.008

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一个格上不经意传输协议的量子安全性分析 Article

Mo-meng LIU, Juliane KRÄMER, Yu-pu HU, Johannes BUCHMANN

《信息与电子工程前沿（英文）》 2017年第18卷第9期页码 1348-1369 doi: 10.1631/FITEE.1700039

摘要：不经意传输协议（oblivious transfer, OT）因其简易的密码功能广泛应用于安全多方计算。以往OT协议都是基于传统数论问题（例如，离散对数，大数分解问题）所构造的，随着量子计算技术的发展，基于传统困难问题的OT协议安全性受到极大的威胁。因此，人们转而考虑使用后量子密码技术替代以往OT协议所依赖的传统困难问题。目前，已有一些基于后量子密码体制的OT协议被提出。然而，大多数后量子密码构造只在假设传统敌手存在的环境下证明其方案安全性。在本文中，我们在量子敌手存在的环境下，证明一个基于格公钥密码的OT协议（[PVW08]）的安全性。首先我们使用量子平移定理（[Unr10]）证明该协议的安全性可以完全平移到量子环境中，此外，我们还使用其他两个专用于分析后量子密码原语的分析模型（[HSS11]，[Son14]）从不同的角度对该协议进行安全性分析，从而保证我们给出的量子安全证明的正确性。我们的成果可以看作对后量子密码协议分析模型的一个实际应用实例。

关键词：不经意传输；后量子；格公钥；带差错学习；通用可复合

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Numerical study on natural convection in a square enclosure containing a rectangular heated cylinder

Jianhua LU, Zhaoli GUO, Zhenhua CHAI, Baochang SHI,

《能源前沿（英文）》 2009年第3卷第4期页码 373-380 doi: 10.1007/s11708-009-0078-x

摘要： In this paper, the natural convection in a square enclosure with a rectangular heated cylinder is investigated via the lattice Boltzmann method. A detailed study is conducted on the effect of the cylinder width and the Rayleigh number on the fluid flow and heat transfer. The flow structures and heat transfer patterns are classified into eight buoyant regimes, i.e., four steady regimes, two periodic regimes, one multiple periodic regime, and one chaos regime, two of which are reported for the first time.

关键词： natural convection buoyant regime heated cylinder lattice Boltzmann

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一种基于新型耦合映像格子系统和DNA运算的图像压缩加密方案 Research Article

李媛媛1,游晓庆2,卢剑权3,楼俊钢4,5

《信息与电子工程前沿（英文）》 2023年第24卷第6期页码 813-827 doi: 10.1631/FITEE.2200645

摘要：本文提出一种基于混合线性-非线性耦合逻辑映像格子（NMLNCML）系统和DNA运算的有效图像加密方案。所提出的NMLNCML系统增强了系统的混沌特性，适用于图像加密。该加密系统具有大量的密钥空间；对密钥的敏感性高；对选择明文攻击、统计学攻击和差分攻击具有很强的抵抗能力；并且对一定程度的噪声和数据丢失有很好的鲁棒性。提出的图像密码系统采用置乱—压缩—扩散的架构。首先，通过离散小波变换将普通图像变换为稀疏系数矩阵，并对系数矩阵执行与明文相关的Arnold置乱。然后，采用半张量积（STP）压缩感知对系数矩阵进行压缩和加密。最后，通过DNA随机编码、DNA加法，和位XOR运算来扩散压缩系数矩阵。NMLNCML系统用于在压缩传感的STP测量矩阵和DNA操作中的伪随机序列中生成混沌元素。SHA-384函数用于产生明文密钥，从而使所提出的加密算法对原始图像高度敏感。仿真结果和性能分析验证了该方案的安全性和有效性。

关键词：压缩感知；耦合映像格子（CML）；DNA运算；半张量积

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标题作者时间类型操作

Uncertainty of concrete strength in shear and flexural behavior of beams using lattice modeling

期刊论文

Modeling nanostructured catalyst layer in PEMFC and catalyst utilization

Jiejing ZHANG, Pengzhen CAO, Li XU, Yuxin WANG

期刊论文

Compressive behavior and energy absorption of polymeric lattice structures made by additive manufacturing

Sheng WANG, Jun WANG, Yingjie XU, Weihong ZHANG, Jihong ZHU

期刊论文

Simulation of interfacial Marangoni convection in gas-liquid mass transfer by lattice Boltzmann method