• Title/Summary/Keyword: Key element

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On the receding contact plane problem for bi-FGM-layers indented by a flat indenter

  • Cong Wang;Jie Yan;Rui Cao
    • Structural Engineering and Mechanics
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    • v.85 no.5
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    • pp.621-633
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    • 2023
  • The major objective of this paper is to study the receding contact problem between two functional graded layers under a flat indenter. The gravity is assumed negligible, and the shear moduli of both layers are assumed to vary exponentially along the thickness direction. In the absence of body forces, the problem is reduced to a system of Fredholm singular integral equations with the contact pressure and contact size as unknowns via Fourier integral transform, which is transformed into an algebraic one by the Gauss-Chebyshev quadratures and polynomials of both the first and second kinds. Then, an iterative speediest descending algorithm is proposed to numerically solve the system of algebraic equations. Both semi-analytical and finite element method, FEM solutions for the presented problem validate each other. To improve the accuracy of the numerical result of FEM, a graded FEM solution is performed to simulate the FGM mechanical characteristics. The results reveal the potential links between the contact stress/size and the indenter size, the thickness, as well as some other material properties of FGM.

An Implementation of Security Key Management System by LDAP (LDAP을 이용한 보안 키 관리 시스템 구현)

  • Yoon, Sung-Jung;Kim, Geon-Ung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.3
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    • pp.437-445
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    • 2006
  • The security key management function is a key element to secure network environment, and many protocols include IPSec, HIP, etc. demand this function. There are two solutions to provide the key management function in the network layer, one is a method for storing security key material in the directory, and the other is a method for storing security key material in DNS. In this paper we present an implementation of key management system by LDAP. We deployed the open source solutions for directory service(OpenLDAP), cryptographic algorithm (FLINT/C), IPSec(FreeS/WAN), and verified the key management system by the encrypted message exchange and the interoperability test by un daemon.

Nonlinear vibration analysis of composite laminated trapezoidal plates

  • Jiang, Guoqing;Li, Fengming;Li, Xinwu
    • Steel and Composite Structures
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    • v.21 no.2
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    • pp.395-409
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    • 2016
  • Nonlinear vibration characteristics of composite laminated trapezoidal plates are studied. The geometric nonlinearity of the plate based on the von Karman's large deformation theory is considered, and the finite element method (FEM) is proposed for the present nonlinear modeling. Hamilton's principle is used to establish the equation of motion of every element, and through assembling entire elements of the trapezoidal plate, the equation of motion of the composite laminated trapezoidal plate is established. The nonlinear static property and nonlinear vibration frequency ratios of the composite laminated rectangular plate are analyzed to verify the validity and correctness of the present methodology by comparing with the results published in the open literatures. Moreover, the effects of the ply angle and the length-high ratio on the nonlinear vibration frequency ratios of the composite laminated trapezoidal plates are discussed, and the frequency-response curves are analyzed for the different ply angles and harmonic excitation forces.

Nonlinear time history analysis of a pre-stressed concrete containment vessel model under Japan's March 11 earthquake

  • Duan, An;Zhao, Zuo-Zhou;Chen, Ju;Qian, Jia-Ru;Jin, Wei-Liang
    • Computers and Concrete
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    • v.13 no.1
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    • pp.1-16
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    • 2014
  • To evaluate the behavior of the advanced unbonded pre-stressed concrete containment vessel (UPCCV) for one typical China nuclear power plant under Japan's March 11 earthquake, five nonlinear time history analysis and a nonlinear static analysis of a 1:10 scale UPCCV structure have been carried out with MSC.MARC finite element program. Comparisons between the analytical and experimental results demonstrated that the developed finite element model can predict the earthquake behavior of the UPCCV with fair accuracy. The responses of the 1:10 scale UPCCV subjected to the 11 March 2011 Japan earthquakes recorded at the MYG003 station with the peak ground acceleration (PGA) of 781 gal and at the MYG013 station with the PGA of 982 gal were predicted by the dynamic analysis. Finally, a static analysis was performed to seek the ultimate load carrying capacity for the 1:10 scale UPCCV.

Experimental and theoretical behaviour analysis of steel suspension members subjected to tension and bending

  • Kmet, Stanislav;Tomko, Michal;Bin, Molinne
    • Steel and Composite Structures
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    • v.13 no.4
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    • pp.343-365
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    • 2012
  • Steel suspension members subjected to tension and bending offer an economical and efficient alternative for many structural problems. This paper is concerned with the elastic and elastic-plastic behaviour of suspension members with bending stiffness subjected to vertical point and uniformly distributed loads. An experimental study is described which focuses on the response of three suspension members with various T-shaped steel hot rolled sections and geometric configurations. The tests enable direct assessment of the influence of a key parameter such as the sag-to-span ratio on the response of suspension members. Detailed nonlinear finite-element models are generated to provide a tool for theoretical analyses and to facilitate further understanding of the behaviour. Results demonstrate that experimentally obtained responses can generally be closely predicted numerically because there are relatively good agreements between finite element and tests results. The results and observations of subsequent numerical parametric studies offer an insight into the key factors that govern the behaviour of suspension members with bending stiffness in the elastic-plastic range.

A Parameter Selection Method for Multi-Element Resonant Converters with a Resonant Zero Point

  • Wang, Yifeng;Yang, Liang;Li, Guodong;Tu, Shijie
    • Journal of Power Electronics
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    • v.18 no.2
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    • pp.332-342
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    • 2018
  • This paper proposes a parameter design method for multi-element resonant converters (MERCs) with a unique resonant zero point (RZP). This method is mainly composed of four steps. These steps include program filtration, loss comparison, 3D figure fine-tuning and priority compromise. It features easy implementation, effectiveness and universal applicability for almost all of the existing RZP-MERCs. Meanwhile, other design methods are always exclusive for a specific topology. In addition, a novel dual-CTL converter is also proposed here. It belongs to the RZP-MERC family and is designed in detail to explain the process of parameter selection. The performance of the proposed method is verified experimentally on a 500W prototype. The obtained results indicate that with the selected parameters, an extensive dc voltage gain is obtained. It also possesses over-current protection and minimal switching loss. The designed converter achieves high efficiencies among wide load ranges, and the peak efficiency reaches 96.9%.

An approach of evaluation and mechanism study on the high and steep rock slope in water conservancy project

  • Yang, Meng;Su, Huaizhi;Wen, Zhiping
    • Computers and Concrete
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    • v.19 no.5
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    • pp.527-535
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    • 2017
  • In this study, an aging deformation statistical model for a unique high and steep rock slope was proposed, and the aging characteristic of the slope deformation was better reflected. The slope displacement was affected by multiple-environmental factors in multiple scales and displayed the same tendency with a rising water level. The statistical model of the high and steep rock including non-aging factors was set up based on previous analyses and the study of the deformation and residual tendency. The rule and importance of the water level factor as a non-aging unit was analyzed. A partitioned statistical model and mutation model were established for the comprehensive cumulative displacement velocity with the monitoring study under multiple factors and multiple parameters. A spatial model was also developed to reflect and predict the whole and sectional deformation character by combining aging, deformation and space coordinates. A neural network model was built to fit and predict the deformation with a high degree of precision by mastering its feature of complexity and randomness. A three-dimensional finite element model of the slope was applied to approach the structure character using numerical simulations. Further, a three-dimensional finite element model of the slope and dam was developed, and the whole deformation state was analyzed. This study is expected to provide a powerful and systematic method to analyze very high, important and dangerous slopes.

Missing Elements in Surgical Pathology Reports: Breast, Colon and Stomach Cancers

  • Kadivar, Maryam;Rahimabad, Parnian Kheirkhah
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.3
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    • pp.1469-1472
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    • 2016
  • Cancer pathology reports play an important role in choice of patient care. They provide crucial information concerning diagnosis, therapy options, and prognosis. Professional pathology institutions, such as the College of American Pathologists (CAP), have developed checklists to ensure the presence of all the required elements in reports. In this study, 438 surgical pathology reports of patients with breast (148), colon (147), and stomach cancer (143) were evaluated with respect to the presence of mandated elements according to CAP checklists. The most common missing element in all the three types of cancer was 'staging' (73.6, 53.1, and 56.6% in breast, colon, and stomach cancer reports missed 'staging', respectively). The second most missing element was 'tumor site' in breast (64.2%) and stomach cancer (30.1%), and 'procedure' in colon cancer (29.3%). 'Perineural invasion' was the third most missing element in the three types of cancer (25.7, 17.0, and 22.4% in breast, colon, and stomach cancer, respectively). Only 11.4% of reports included all key elements required by CAP. The use of checklists was associated with higher rate of completeness. This study demonstrates that the key elements requiring the information on the requisition forms from the clinicians are commonly missed, leading to ambiguity.

Numerical Simulation of Interactions between Corrosion Pits on Stainless Steel under Loading Conditions

  • Wang, Haitao;Han, En-Hou
    • Corrosion Science and Technology
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    • v.16 no.2
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    • pp.64-68
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    • 2017
  • The interactions between corrosion pits on stainless steel under loading conditions are studied by using a cellular automata model coupled with finite element method at a mesoscopic scale. The cellular automata model focuses on a metal/film/electrolyte system, including anodic dissolution, passivation, diffusion of hydrogen ions and salt film hydrolysis. The Chopard block algorithm is used to improve the diffusion simulation efficiency. The finite element method is used to calculate the stress concentration on the pit surface during pit growth, and the effect of local stress and strain on anodic current is obtained by using the Gutman model, which is used as the boundary conditions of the cellular automata model. The transient current characteristics of the interactions between corrosion pits under different simulation factors including the breakdown of the passive film at the pit mouth and the diffusion of hydrogen ions are analyzed. The analysis of the pit stability product shows that the simulation results are close to the experimental conclusions.

Bonded-cluster simulation of tool-rock interaction using advanced discrete element method

  • Liu, Weiji;Zhu, Xiaohua;Zhou, Yunlai;Li, Tao;Zhang, Xiangning
    • Structural Engineering and Mechanics
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    • v.72 no.4
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    • pp.469-477
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    • 2019
  • The understanding of tool-rock interaction mechanism is of high essence for improving the rock breaking efficiency and optimizing the drilling parameters in mechanical rock breaking. In this study, the tool-rock interaction models of indentation and cutting are carried out by employing the discrete element method (DEM) to examine the rock failure modes of various brittleness rocks and critical indentation and cutting depths of the ductile to brittle failure mode transition. The results show that the cluster size and inter-cluster to intra-cluster bond strength ratio are the key factors which influence the UCS magnitude and the UCS to BTS ratio. The UCS to BTS strength ratio can be increased to a more realistic value using clustered rock model so that the characteristics of real rocks can be better represented. The critical indentation and cutting depth decrease with the brittleness of rock increases and the decreasing rate reduces dramatically against the brittleness value. This effort may lead to a better understanding of rock breaking mechanisms in mechanical excavation, and may contribute to the improvement in the design of rock excavation machines and the related parameters determination.