• 제목/요약/키워드: UD

검색결과 293건 처리시간 0.024초

The critical buckling load of reinforced nanocomposite porous plates

  • Guessas, Habib;Zidour, Mohamed;Meradjah, Mustapha;Tounsi, Abdelouahed
    • Structural Engineering and Mechanics
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    • 제67권2호
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    • pp.115-123
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    • 2018
  • By using the first order shear deformation plate theory (FSDT) in the present paper, the effect of porosity on the buckling behavior of carbon nanotube-reinforced composite porous plates has been investigated analytically. Two types of distributions of uniaxially aligned reinforcement material are utilized which uniformly (UD-CNT) and functionally graded (FG-CNT) of plates. The analytical equations of the model are derived and the exact solutions for critical buckling load of such type's plates are obtained. The convergence of the method is demonstrated and the present solutions are numerically validated by comparison with some available solutions in the literature. The central thesis studied and discussed in this paper is the Influence of Various parameters on the buckling of carbon nanotube-reinforced porous plate such as aspect ratios, volume fraction, types of reinforcement, the degree of porosity and plate thickness. On the question of porosity, this study found that there is a great influence of their variation on the critical buckling load. It is revealed that the critical buckling load decreases as increasing coefficients of porosity.

Implication of rubber-steel bearing nonlinear models on soft storey structures

  • Saiful Islam, A.B.M.;Hussain, Raja Rizwan;Jumaat, Mohammed Zamin;Mahfuz ud Darain, Kh.
    • Computers and Concrete
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    • 제13권5호
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    • pp.603-619
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    • 2014
  • Soft storey buildings are characterised by having a storey that has a large amount of open space. This soft storey creates a major weak point during an earthquake. As the soft stories are typically associated with retail spaces and parking garages, they are often on the lower levels of tall building structures. Thus, when these stories collapse, the entire building can also collapse, causing serious structural damage that may render the structure completely unusable. The use of special soft storey is predominant in the tall building structures constructed by several local developers, making the issue important for local building structures. In this study, the effect of the incorporation of an isolator on the seismic behaviour of tall building structures is examined. The structures are subjected to earthquakes typical of the local city, and the isolator is incorporated with the appropriate isolator time period and damping ratio. A FEM-based computational relationship is proposed to increase the storey height so as to incorporate the isolator with the same time period and damping ratio for both a lead rubber bearing (LRB) and high-damping rubber bearing (HDRB). The study demonstrates that the values of the FEM-based structural design parameters are greatly reduced when the isolator is used. It is more beneficial to incorporate a LRB than a HDRB.

Micro Finance and Economic Development: The Role of Microfinance Institutions Outreach in Pakistan

  • ZEB, Naveeda;JALAL, Raja Nabeel-Ud-Din;FAYYAZ, Um-E-Roman;ZAHEER, Muhammad Asif
    • The Journal of Asian Finance, Economics and Business
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    • 제8권5호
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    • pp.117-126
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    • 2021
  • Microfinance focuses on economic development at a minute level. Microfinance is adopted to reduce the poverty level in the economic system. This study is conducted to investigate the microfinance institutions' outreach, its growth, and challenges faced by the Microfinance Banks (MFBs) and Microfinance Institutions (MFIs). Data is collected from MFBs and MFIs working in Muzaffarabad as well as from interviews and focus group discussions. Findings are based upon lending, headcount ratio, offers, the value of their offer, and the possible growth chances of microfinance in Muzaffarabad. In addition to this, the challenges associated with microfinance outreach have been highlighted during analysis and guidelines have been provided to the MFBs and MFIs to increase their outreach. The sector is financially unstable which is attributable to its reliance on conventional sources of funding. The industry faces several endogenous as well as exogenous challenges from its environment which obstructs its growth. Further, it helps the policymakers to work on the development of the region and provide the base for further future research work.

Nonlinear vibration analysis of carbon nanotube reinforced composite plane structures

  • Rezaiee-Pajand, Mohammad;Masoodi, Amir R.;Rajabzadeh-Safaei, Niloofar
    • Steel and Composite Structures
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    • 제30권6호
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    • pp.493-516
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    • 2019
  • This paper is dedicated to nonlinear static and free vibration analysis of Uniform Distributed Carbon Nanotube Reinforced Composite (UD-CNTRC) structures under in-plane loading. The authors have suggested an efficient six-node triangular element. Mixed Interpolation of Tensorial Components (MITC) approach is employed to alleviate the membrane locking phenomena. Moreover, the behavior of the well-known LST element is considerably improved by applying an additional linear interpolation on the strain fields. Based on the rule of mixture, the properties of CNTRC are obtained. In this study, only the uniform distributed CNTs are employed through the thickness direction of element. To achieve the natural frequencies and shape modes, the eigenvalue problem is also solved. Using Total Lagrangian Principles, large amplitude free vibration is considered based on the first normalized mode shape of structure. Different well-known plane problem benchmarks and some proposed ones are studied to validate the accuracy and capability of authors' formulations. In addition, the effects of length to the height ratio of beam, CNT's characteristics, support conditions and normalized amplitude parameter on the linear and nonlinear vibration parameters are investigated.

Nonlinear analysis of viscoelastic micro-composite beam with geometrical imperfection using FEM: MSGT electro-magneto-elastic bending, buckling and vibration solutions

  • Alimirzaei, S.;Mohammadimehr, M.;Tounsi, Abdelouahed
    • Structural Engineering and Mechanics
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    • 제71권5호
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    • pp.485-502
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    • 2019
  • In this research, the nonlinear static, buckling and vibration analysis of viscoelastic micro-composite beam reinforced by various distributions of boron nitrid nanotube (BNNT) with initial geometrical imperfection by modified strain gradient theory (MSGT) using finite element method (FEM) are presented. The various distributions of BNNT are considered as UD, FG-V and FG-X and also, the extended rule of mixture is used to estimate the properties of micro-composite beam. The components of stress are dependent to mechanical, electrical and thermal terms and calculated using piezoelasticity theory. Then, the kinematic equations of micro-composite beam using the displacement fields are obtained. The governing equations of motion are derived using energy method and Hamilton's principle based on MSGT. Then, using FEM, these equations are solved. Finally the effects of different parameters such as initial geometrical imperfection, various distributions of nanotube, damping coefficient, piezoelectric constant, slenderness ratio, Winkler spring constant, Pasternak shear constant, various boundary conditions and three material length scale parameters on the behavior of nonlinear static, buckling and vibration of micro-composite beam are investigated. The results indicate that with an increase in the geometrical imperfection parameter, the stiffness of micro-composite beam increases and thus the non-dimensional nonlinear frequency of the micro structure reduces gradually.

Static and dynamic behavior of (FG-CNT) reinforced porous sandwich plate using energy principle

  • Medani, Mohammed;Benahmed, Abdelillah;Zidour, Mohamed;Heireche, Houari;Tounsi, Abdelouahed;Bousahla, Abdelmoumen Anis;Tounsi, Abdeldjebbar;Mahmoud, S.R.
    • Steel and Composite Structures
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    • 제32권5호
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    • pp.595-610
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    • 2019
  • This paper deals with the static and dynamic behavior of Functionally Graded Carbon Nanotubes (FG-CNT)-reinforced porous sandwich (PMPV) polymer plate. The model of nanocomposite plate is investigated within the first order shear deformation theory (FSDT). Two types of porous sandwich plates are supposed (sandwich with face sheets reinforced / homogeneous core and sandwich with homogeneous face sheets / reinforced core). Functionally graded Carbon Nanotubes (FG-CNT) and uniformly Carbon Nanotubes (UD-CNT) distributions of face sheets or core porous plates with uniaxially aligned single-walled carbon nanotubes are considered. The governing equations are derived by using Hamilton's principle. The solution for bending and vibration of such type's porous plates are obtained. The detailed mathematical derivations are provided and the solutions are compared to some cases in the literature. The effect of the several parameters of reinforced sandwich porous plates such as aspect ratios, volume fraction, types of reinforcement, number of modes and thickness of plate on the bending and vibration analyses are studied and discussed. On the question of porosity, this study found that there is a great influence of their variation on the static and vibration of porous sandwich plate.

JPEG Pleno: Providing representation interoperability for holographic applications and devices

  • Schelkens, Peter;Ebrahimi, Touradj;Gilles, Antonin;Gioia, Patrick;Oh, Kwan-Jung;Pereira, Fernando;Perra, Cristian;Pinheiro, Antonio M.G.
    • ETRI Journal
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    • 제41권1호
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    • pp.93-108
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    • 2019
  • Guaranteeing interoperability between devices and applications is the core role of standards organizations. Since its first JPEG standard in 1992, the Joint Photographic Experts Group (JPEG) has published several image coding standards that have been successful in a plethora of imaging markets. Recently, these markets have become subject to potentially disruptive innovations owing to the rise of new imaging modalities such as light fields, point clouds, and holography. These so-called plenoptic modalities hold the promise of facilitating a more efficient and complete representation of 3D scenes when compared to classic 2D modalities. However, due to the heterogeneity of plenoptic products that will hit the market, serious interoperability concerns have arisen. In this paper, we particularly focus on the holographic modality and outline how the JPEG committee has addressed these tremendous challenges. We discuss the main use cases and provide a preliminary list of requirements. In addition, based on the discussion of real-valued and complex data representations, we elaborate on potential coding technologies that range from approaches utilizing classical 2D coding technologies to holographic content-aware coding solutions. Finally, we address the problem of visual quality assessment of holographic data covering both visual quality metrics and subjective assessment methodologies.

탄소섬유 복합재 피로수명의 통계적 특성 연구 (A Study on Statistical Characteristics of Fatigue Life of Carbon Fiber Composite)

  • 주영식;이원준;서보휘;임승규
    • 한국항공우주학회지
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    • 제47권1호
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    • pp.35-40
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    • 2019
  • 본 연구의 목적은 항공기 구조개발에 널리 적용되고 있는 탄소섬유 복합재의 피로특성을 확인하고, 실기체 피로시험에 활용되고 있는 자료를 획득하는 것이다. 복합재 구조의 내구성 및 손상허용성의 평가는 주로 피로시험을 통하여 이루어지며, 실기체 피로시험에 적용되고 있는 파라미터에는 피로수명계수와 하중증대계수가 있다. 탄소섬유/에폭시 일방향 및 직물형 복합재로 시편을 제작하였으며, 응력비와 적층패턴을 달리하여 피로시험을 수행하였다. Sendeckyj 모델을 적용한 와이블 분포와 개별적인 피로수명에 대한 와이블 분포를 이용하여 형상 파라미터를 분석하였다. 또한 신뢰도를 고려한 피로수명계수와 하중증대계수를 평가하였다.

Islamic Work Ethics and Employee Performance: The Role of Islamic Motivation, Affective Commitment, and Job Satisfaction

  • AFLAH, Kuntarno Noor;SUHARNOMO, Suharnomo;MAS'UD, Fuad;MURSID, Ali
    • The Journal of Asian Finance, Economics and Business
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    • 제8권1호
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    • pp.997-1007
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    • 2021
  • This study aims to redesign and find out the role of Islamic work ethics in influencing Islamic motivation, affective commitment, job satisfaction, and employee performance. Respondents in this study are populations of various cross-sectoral and cross-profession employees, such as government and private workers, soldiers, educators (teachers and lecturers) in various offices in Central Java. 220 questionnaires were distributed to all respondents, but the number of the returned questionnaires was 200. Thus, totally, this study analyzed 200 questionnaires. Data are analyzed using Structural Equation Modelling (SEM). The results show that the eight hypotheses are accepted: there is a positive and significant influence of Islamic work ethics on Islamic motivation; there is a positive and significant effect of Islamic work ethics on job satisfaction; there is a positive and significant effect of Islamic work on affective commitment; there is a positive and significant influence of Islamic motivation on affective commitment; there is a positive and significant influence of Islamic motivation on job satisfaction; there is a positive and significant effect of job satisfaction on employee performance; there is a positive and significant effect of affective commitment on employee performance; there is a positive and significant influence of Islamic motivation on employee performance.

Perceived Enjoyment, Application Self-efficacy, and Subjective Norms as Determinants of Behavior Intention in Using OVO Applications

  • WINARNO, Wahyu Agus;MAS'UD, Imam;PALUPI, Trias Widya
    • The Journal of Asian Finance, Economics and Business
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    • 제8권2호
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    • pp.1189-1200
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    • 2021
  • This study examines the role of perceived enjoyment, self-efficacy, and subjective norms as determinants of behavioral intention to use the OVO application. This study's target population is the users of the OVO application who have used it as an electronic transaction. This study's population was the OVO application users as an electronic transaction tool in Jember Regency. Samples were randomly selected at the time of the survey with specific criteria. The survey location is determined at the Plaza because it is a shopping center that mostly has payments at OVO partner merchants. The model empirically tested using data gathered from 150 respondents of OVO users. The research model was tested by using the structural equation modeling (SEM) approach. The results showed that all constructs in the original TAM model were statistically significant. Subjective norm has a positive effect on perceived usefulness, and perceived enjoyment positively affects perceived ease of use of OVO applications. On the other hand, applications' self-efficacy does not affect the perceived ease of using OVO applications for electronic transactions. This condition shows that subjective norms are dominant external individual perspectives compared to self-efficacy, which are personal internal characteristics in determining the behavioral intention of using OVO applications in electronic transactions.