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Fitzhugh-Nagumo；混沌；分数阶；磁通量 1

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Discontinuous mechanical behaviors of existing shield tunnel with stiffness reduction at longitudinal

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 37-52 doi: 10.1007/s11709-022-0920-3

摘要： An analytical model is proposed to estimate the discontinuous mechanical behavior of an existing shield tunnel above a new tunnel. The existing shield tunnel is regarded as a Timoshenko beam with longitudinal joints. The opening and relative dislocation of the longitudinal joints can be calculated using Dirac delta functions. Compared with other approaches, our method yields results that are consistent with centrifugation test data. The effects of the stiffness reduction at the longitudinal joints (α and β), the shearing stiffness of the Timoshenko beam GA, and different additional pressure profiles on the responses of the shield tunnel are investigated. The results indicate that our proposed method is suitable for simulating the discontinuous mechanical behaviors of existing shield tunnels with longitudinal joints. The deformation and internal forces decrease as α, β, and GA increase. The bending moment and shear force are discontinuous despite slight discontinuities in the deflection, opening, and dislocation. The deflection curve is consistent with the additional pressure profile. Extensive opening, dislocation, and internal forces are induced at the location of mutation pressures. In addition, the joints allow rigid structures to behave flexibly in general, as well as allow flexible structures to exhibit locally rigid characteristics. Owing to the discontinuous characteristics, the internal forces and their abrupt changes at vulnerable sections must be monitored to ensure the structural safety of existing shield tunnels.

关键词： tunnel–soil interaction     discontinuous analysis     longitudinal joints     existing shield tunnel     Timoshenko beam     Dirac delta function    

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Bending and vibration of a discontinuous beam with a curvic coupling under different axial forces

Heng LIU, Jie HONG, Dayi ZHANG

《机械工程前沿（英文）》 2020年 第15卷 第3期   页码 417-429 doi: 10.1007/s11465-019-0584-4

摘要： The transverse stiffness and vibration characteristics of discontinuous beams can significantly differ from those of continuous beams given that an abrupt change in stiffness may occur at the interface of the former. In this study, the equations for the deflection curve and vibration frequencies of a simply supported discontinuous beam under axial loads are derived analytically on the basis of boundary, continuity, and deformation compatibility conditions by using equivalent spring models. The equation for the deflection curve is solved using undetermined coefficient methods. The normal function of the transverse vibration equation is obtained by separating variables. The differential equations for the beam that consider moments of inertia, shearing effects, and gyroscopic moments are investigated using the transfer matrix method. The deflection and vibration frequencies of the discontinuous beam are studied under different axial loads and connection spring stiffness. Results show that deflection decreases and vibration frequencies increase exponentially with increasing connection spring stiffness. Moreover, both variables remain steady when connection spring stiffness reaches a considerable value. Lastly, an experimental study is conducted to investigate the vibration characteristics of a discontinuous beam with a curvic coupling, and the results exhibit a good match with the proposed model.

关键词： discontinuous beam     bending stiffness     transverse vibration     axial loads     gyroscopic moments    

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Erratum to: Bending and vibration of a discontinuous beam with a curvic coupling under different axial

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0709-z

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A continuous/discontinuous deformation analysis (CDDA) method based on deformable blocks for fracture

Yongchang CAI, Hehua ZHU, Xiaoying ZHUANG

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 369-378 doi: 10.1007/s11709-013-0222-x

摘要： In the framework of finite element meshes, a novel continuous/discontinuous deformation analysis (CDDA) method is proposed in this paper for modeling of crack problems. In the present CDDA, simple polynomial interpolations are defined at the deformable block elements, and a link element is employed to connect the adjacent block elements. The CDDA is particularly suitable for modeling the fracture propagation because the switch from continuous deformation analysis to discontinuous deformation analysis is natural and convenient without additional procedures. The SIFs (stress intensity factors) for various types of cracks, such as kinked cracks or curved cracks, can be easily computed in the CDDA by using the virtual crack extension technique (VCET). Both the formulation and implementation of the VCET in CDDA are simple and straightforward. Numerical examples indicate that the present CDDA can obtain high accuracy in SIF results with simple polynomial interpolations and insensitive to mesh sizes, and can automatically simulate the crack propagation without degrading accuracy.

关键词： fracture     crack     propagation     deformable block     continuous/discontinuous deformation analysis (CDDA)    

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Simulation of blast induced crater in jointed rock mass by discontinuous deformation analysis method

Youjun NING, Xinmei AN, Jun YANG, Guowei MA,

《结构与土木工程前沿（英文）》 2010年 第4卷 第2期   页码 223-232 doi: 10.1007/s11709-010-0022-5

摘要： Rock blasting is a dynamic process accompanied with the propagations of shock waves and the dispersion of the explosion gas. This paper adopts the discontinuous deformation analysis (DDA) method to simulate the rock blasting process. A dynamic parameter adjustment and the non-reflecting boundary condition are implemented in the DDA method. The sub-block DDA method to simulate fracture problems is used. The blasting process in jointed rock mass is simulated by application of the explosion gas pressure on the expanding borehole walls and induced connected fracture surfaces around the boreholes. The blast craters with different overburdens are derived. The whole process including the explosion gas dispersion, borehole expansion, rock mass failure and cast, and the formation of the final blasting piles in rock blasting are well reproduced numerically. Parametric study for different overburdens is carried out, and the results are analyzed and discussed.

关键词： blast crater     jointed rock mass     explosion gas pressure     discontinuous deformation analysis (DDA) method    

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Effect of end-to-end invagination pancreaticojejunostomy with circle discontinuous U suture in pancreatic

ZHANG Xuewen, XUAN Wei, JIANG Tao, JI Degang, YANG Yongsheng, ZHANG Dan, XIE Yingjun, MENG Zihui, ZHAO Jisheng

《医学前沿（英文）》 2007年 第1卷 第1期   页码 46-48 doi: 10.1007/s11684-007-0009-3

摘要： The aim of this paper is to summarize the methods of pancreaticojejunostomy in the pancreatic operation and to study the safety and feasibility of a new operative method called end-to-end invagination pancreaticojejunostomy with circle discontinuous U suture to prevent fistula of pancreaticojejunostomy. Eight-three patients with pancreaticoduodenectomy in the 3rd Hospital, Jilin University from 2001 January to 2006 April were reviewed. The incidences of pancreatic fistula with different types of pancreaticojejunostomy were compared. The overall incidence rate of pancreatic fistula was 26.5% (22/83). No pancreatic fistula occurred in end-to-end invagination pancreaticojejunostomy with circle discontinuous U suture. The incidence rate of the fistula following end-to-end invagination pancreaticojejunostomy with circle discontinuous U suture was significantly lower than that of traditional end-to-end pancreaticojejunostomy [40%, (10/25), <0.01] and end-to-side pancreaticojejunostomy [27.3%, (12/44), <0.05], but no significant difference (>0.05) between traditional end-to-end pancreaticojejunostomy and end-to-side pancreaticojejunostomy was discovered. End-to-end invagination pancreaticojejunostomy with circle discontinuous U suture has a definite effect on avoiding pancreatic fistula following pancreaticojejunostomy and is worth being recommended. But the cases were limited, so this method would still need to be observed and confirmed further in the future.
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Three-dimensional modeling of borehole data cored from engineering rock mass

HE Manchao, LI Xueyuan, LIU Bin, XU Nengxiong

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 334-339 doi: 10.1007/s11709-007-0044-9

摘要： Vast data from the drilling and geophysical prospecting are reliable original information to describe the space state of engineering rock mass, and one of the main difficulties in three-dimensional (3D) modeling of engineering rock mass is the processing of the primary data. From the viewpoint of 3D modeling, the engineering rock masses are classified as four basic types according to their geometric characteristics of geologic structure: (1) continuum rock mass; (2) discontinuous rock mass; (3) overturned fold rock mass and (4) intrusive rock mass. Because drilling data are very important to describe the characters of multi-scale of the spatial data for rock mass, the rule of how to process drilling data is developed to help appropriately display them in the viewpoint of 3D space. According to the characteristics of rock mass layers, the processing method of drilling data for 3D modeling of engineering rock masses, along with the layer thicknesses, is also proposed, including the evaluation rules and the extensive direction for original borehole data. By this method, the typical 3D data modeled is completed and the model form of the engineering rock mass is developed. By this example, it is finally verified that the method presented is successful and feasible to process 3D engineering rock mass.

关键词： three-dimensional     discontinuous     primary     extensive direction     engineering    

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Adaptive simulation of wave propagation problems including dislocation sources and random media

Hassan YOUSEFI, Jamshid FARJOODI, Iradj MAHMOUDZADEH KANI

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1054-1081 doi: 10.1007/s11709-019-0536-4

摘要： An adaptive Tikhonov regularization is integrated with an h-adaptive grid-based scheme for simulation of elastodynamic problems, involving seismic sources with discontinuous solutions and random media. The Tikhonov method is adapted by a newly-proposed detector based on the MINMOD limiters and the grids are adapted by the multiresolution analysis (MRA) via interpolation wavelets. Hence, both small and large magnitude physical waves are preserved by the adaptive estimations on non-uniform grids. Due to developing of non-dissipative spurious oscillations, numerical stability is guaranteed by the Tikhonov regularization acting as a post-processor on irregular grids. To preserve waves of small magnitudes, an adaptive regularization is utilized: using of smaller amount of smoothing for small magnitude waves. This adaptive smoothing guarantees also solution stability without over smoothing phenomenon in stochastic media. Proper distinguishing between noise and small physical waves are challenging due to existence of spurious oscillations in numerical simulations. This identification is performed in this study by the MINMOD limiter based algorithm. Finally, efficiency of the proposed concept is verified by: 1) three benchmarks of one-dimensional (1-D) wave propagation problems; 2) P-SV point sources and rupturing line-source including a bounded fault zone with stochastic material properties.

关键词： adaptive wavelet     adaptive smoothing     discontinuous solutions     stochastic media     spurious oscillations     Tikhonov regularization     minmod limiter    

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Experimental study of pollution effect on the behavior of high voltage insulators under alternative current

Hani BENGUESMIA, Nassima M’ZIOU, Ahmed BOUBAKEUR

《能源前沿（英文）》 2021年 第15卷 第1期   页码 213-221 doi: 10.1007/s11708-017-0479-1

摘要： In this paper, the impact of the conductivity and the distribution of pollution on the behavior of the high voltage insulator cap and pin 1512L, artificially polluted is described. An experimental model in form of a disc is proposed. This experimental model reproduces the real model which is the 1512L insulator. Besides, a comparative study is presented. For this comparative study, different solutions are adopted to s`imulate the pollution (containing NaCl+ distilled water) that has different conductivities for a discontinuous distribution of the pollution on the insulator under an AC voltage. Furthermore, the influence of the pollution on the flashover voltage and the leakage current is studied. Finally, the behavior of real and experimental model of the insulator is investigated.

关键词： 1512L insulator     circular model     artificial pollution     flashover     leakage current     discontinuous pollution     high voltage    

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整数阶与分数阶非连续外磁通量的神经元动力学 Regular Papers

Karthikeyan RAJAGOPAL, Fahimeh NAZARIMEHR, Anitha KARTHIKEYAN, Ahmed ALSAEDI, Tasawar HAYAT, Viet-Thanh PHAM

《信息与电子工程前沿（英文）》 2019年 第20卷 第4期   页码 584-590 doi: 10.1631/FITEE.1800389

摘要： 提出一种改进Fitzugh-Nagumo神经元（MFNN）模型。在此模型基础上，研究了基于整数阶（案例A）与分数阶（案例B）的MFNN系统。在电磁感应和辐射作用下，记忆和感应呈现多种分布，证明该分数阶磁通量适用于非均匀扩散。整数阶非连续磁通量MFNN系统具有混沌和非混沌吸引子。系统动力学分析显示倍周期的产生和消失标志着反单调性，神经元动力学研究未曾报道此现象。在分数阶非连续磁通量MFNN系统中，混沌吸引子和周期吸引子无反单调性。

关键词： Fitzhugh-Nagumo；混沌；分数阶；磁通量    

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标题 作者 时间 类型 操作

Discontinuous mechanical behaviors of existing shield tunnel with stiffness reduction at longitudinal

期刊论文

Bending and vibration of a discontinuous beam with a curvic coupling under different axial forces

Heng LIU, Jie HONG, Dayi ZHANG

期刊论文

Erratum to: Bending and vibration of a discontinuous beam with a curvic coupling under different axial

期刊论文

A continuous/discontinuous deformation analysis (CDDA) method based on deformable blocks for fracture

Yongchang CAI, Hehua ZHU, Xiaoying ZHUANG

期刊论文

Simulation of blast induced crater in jointed rock mass by discontinuous deformation analysis method

Youjun NING, Xinmei AN, Jun YANG, Guowei MA,

期刊论文

Effect of end-to-end invagination pancreaticojejunostomy with circle discontinuous U suture in pancreatic

ZHANG Xuewen, XUAN Wei, JIANG Tao, JI Degang, YANG Yongsheng, ZHANG Dan, XIE Yingjun, MENG Zihui, ZHAO Jisheng

期刊论文

Three-dimensional modeling of borehole data cored from engineering rock mass

HE Manchao, LI Xueyuan, LIU Bin, XU Nengxiong

期刊论文

Adaptive simulation of wave propagation problems including dislocation sources and random media

Hassan YOUSEFI, Jamshid FARJOODI, Iradj MAHMOUDZADEH KANI

期刊论文

Experimental study of pollution effect on the behavior of high voltage insulators under alternative current

Hani BENGUESMIA, Nassima M’ZIOU, Ahmed BOUBAKEUR

期刊论文

整数阶与分数阶非连续外磁通量的神经元动力学

Karthikeyan RAJAGOPAL, Fahimeh NAZARIMEHR, Anitha KARTHIKEYAN, Ahmed ALSAEDI, Tasawar HAYAT, Viet-Thanh PHAM

期刊论文