• 제목/요약/키워드: techno-functional

검색결과 265건 처리시간 0.031초

Dynamic analysis of a functionally graded tapered rotating shaft under thermal load via differential quadrature finite elements method

  • Fethi, Hadjoui;Ahmed, Saimi;Ismail, Bensaid;Abdelhamid, Hadjoui
    • Advances in aircraft and spacecraft science
    • /
    • 제10권1호
    • /
    • pp.19-49
    • /
    • 2023
  • The present study proposes a theoretical and numerical investigation on the dynamic response behaviour of a functional graded (FG) ceramic-metal tapered rotor shaft system, by the differential quadrature finite elements method (DQFEM) to identify the natural frequencies for modelling and analysis of the structure with suitable validations. The purpose of this paper is to explore the influence of heat gradients on the natural frequency of rotation of FG shafts via three-dimensional solid elements, as well as a theoretical examination using the Timoshenko beam mode, which took into account the gyroscopic effect and rotational inertia. The functionally graded material's distribution is described by two distribution laws: the power law and the exponential law. To simulate varied thermal conditions, radial temperature distributions are obtained using the nonlinear temperature distribution (NLTD) and exponential temperature distribution (ETD) approaches. This work deals with the results of the effect on the fundamental frequencies of different material's laws gradation and temperature gradients distributions. Attempts are conducted to identify adequate explanations for the behaviours based on material characteristics. The effect of taper angle and material distribution on the dynamic behaviour of the FG conical rotor system is discussed.

Dynamic intelligent control of composite buildings by using M-TMD and evolutionary algorithm

  • Chen, ZY;Meng, Yahui;Wang, Ruei-Yuan;Peng, Sheng-Hsiang;Yang, Yaoke;Chen, Timothy
    • Steel and Composite Structures
    • /
    • 제42권5호
    • /
    • pp.591-598
    • /
    • 2022
  • The article deals with the possibilities of vibration stimulation. Based on the stability analysis, a multi-scale approach with a modified whole-building model is implemented. The motion equation is configured for a controlled bridge with a MDOF (multiple dynamic degrees of freedom) Tuned Mass Damper (M-TMD) system, and a combination of welding, excitation, and control effects is used with its advanced packages and commercial software submodel. Because the design of high-performance and efficient structural systems has been of interest to practical engineers, systematic methods of structural and functional synthesis of control systems must be used in many applications. The smart method can be stabilized by properly controlling the high frequency injection limits. The simulation results illustrate that the multiple modeling method used is consistent with the accuracy and high computational efficiency. The M-TMD system, even with moderate reductions in critical pressure, can significantly suppress overall feedback on an unregulated design.

Static and stress analyses of bi-directional FG porous plate using unified higher order kinematics theories

  • Mohamed, Salwa;Assie, Amr E.;Mohamed, Nazira;Eltaher, Mohamed A.
    • Steel and Composite Structures
    • /
    • 제45권3호
    • /
    • pp.305-330
    • /
    • 2022
  • This article aims to investigate the static deflection and stress analysis of bi-directional functionally graded porous plate (BDFGPP) modeled by unified higher order kinematic theories to include the shear stress effects, which not be considered before. Different shear functions are described according to higher order models that satisfy the zero-shear influence at the top and bottom surfaces, and hence refrain from the need of shear correction factor. The material properties are graded through two spatial directions (i.e., thickness and length directions) according to the power law distribution. The porosities and voids inside the material constituent are described by different cosine functions. Hamilton's principle is implemented to derive the governing equilibrium equation of bi-directional FG porous plate structures. An efficient numerical differential integral quadrature method (DIQM) is exploited to solve the coupled variable coefficients partial differential equations of equilibrium. Problem validation and verification have been proven with previous prestigious work. Numerical results are illustrated to present the significant impacts of kinematic shear relations, gradation indices through thickness and length, porosity type, and boundary conditions on the static deflection and stress distribution of BDFGP plate. The proposed model is efficient in design and analysis of many applications used in nuclear, mechanical, aerospace, naval, dental, and medical fields.

Free vibration analysis of FGM plates using an optimization methodology combining artificial neural networks and third order shear deformation theory

  • Mohamed Janane Allah;Saad Hassouna;Rachid Aitbelale;Abdelaziz Timesli
    • Steel and Composite Structures
    • /
    • 제49권6호
    • /
    • pp.633-643
    • /
    • 2023
  • In this study, the natural frequencies of Functional Graded Materials (FGM) plates are predicted using Artificial Neural Network (ANN). A model based on Third-order Shear Deformation Theory (TSDT) and FEM is used to train the ANN model. Different training methods are tested to simulate input and output dependency. As this is a parametric model, several architectures and optimization algorithms were tested. The proposed model allows us to minimize the CPU time to evaluate candidate material properties for FGM plate material selection and demonstrate their influence on dynamic behavior. Consequently, the time required for the FGM design process (candidate materials for material selection) and the geometric optimization of the FGM structure would remain reasonable. The ANN model can help industries to produce FGM plates with good mechanical properties of the selected materials. I addition, this model can be used to directly predict vibration behavior by testing a large number of FGM plates, representing all possible combinations of metals and ceramics in today's industry, without having to solve any eigenvalue problems.

New method environment for art design of nanocomposite brick facade of the building

  • Jie Xia;Gholamreza Soleimani Jafari;F. Ghoroughi
    • Steel and Composite Structures
    • /
    • 제51권5호
    • /
    • pp.499-507
    • /
    • 2024
  • The paper delves into an emerging paradigm shift in architectural design, focusing on the development of a cutting-edge methodological framework for the artistic enhancement of nanocomposite brick facades in building construction. This innovative approach represents a fusion of art and science, harnessing the potential of advanced nanotechnology to redefine the aesthetic and functional properties of building exteriors. Central to this new methodology is the integration of state-of-the-art materials and fabrication techniques, aimed at not only elevating the visual appeal of architectural structures but also enhancing their structural robustness and environmental sustainability. By leveraging the unique characteristics of nanocomposite materials, the proposed method opens up new possibilities for pushing the boundaries of traditional brick facade design. Through a meticulous exploration of the intricacies involved in implementing this novel approach, the paper elucidates the transformative impact it can have on the architectural landscape. By marrying creativity with technical precision, the method environment for art design of nanocomposite brick facades promises to usher in a new era of sustainable, visually captivating, and structurally resilient building facades that are poised to redefine the very essence of architectural aesthetics.

A review on dynamic characteristics of nonlocal porous FG nanobeams under moving loads

  • Abdulaziz Saud Khider;Ali Aalsaud;Nadhim M. Faleh;Abeer K. Abd;Mamoon A.A. Al-Jaafari;Raad M. Fenjan
    • Steel and Composite Structures
    • /
    • 제50권1호
    • /
    • pp.15-24
    • /
    • 2024
  • This research presents dynamical reaction investigation of pore-dependent and nano-thickness beams having functional gradation (FG) constituents exposed to a movable particle. The nano-thickness beam formulation has been appointed with the benefits of refined high orders beam paradigm and nonlocal strain gradient theory (NSGT) comprising two scale moduli entitled nonlocality and strains gradient modulus. The graded pore-dependent constituents have been designed through pore factor based power-law relations comprising pore volumes pursuant to even or uneven pore scattering. Therewith, variable scale modulus has been thought-out until process a more accurate designing of scale effects on graded nano-thickness beams. The motion equations have been appointed to be solved via Ritz method with the benefits of Chebyshev polynomials in cosine form. Also, Laplace transform techniques help Ritz-Chebyshev method to obtain the dynamical response in time domain. All factors such as particle speed, pores and variable scale modulus affect the dynamical response.

An approximate method for aerodynamic optimization of horizontal axis wind turbine blades

  • Ying Zhang;Liang Li;Long Wang;Weidong Zhu;Yinghui Li;Jianqiang Wu
    • Wind and Structures
    • /
    • 제38권5호
    • /
    • pp.341-354
    • /
    • 2024
  • This paper presents a theoretical method to deal with the aerodynamic performance and pitch optimization of the horizontal axis wind turbine blades at low wind speeds. By considering a blade element, the functional relationship among the angle of attack, pitch angle, rotational speed of the blade, and wind speed is derived in consideration of a quasi-steady aerodynamic model, and aerodynamic loads on the blade element are then obtained. The torque and torque coefficient of the blade are derived by using integration. A polynomial approximation is applied to functions of the lift and drag coefficients for the symmetric and asymmetric airfoils respectively, where specific expressions of aerodynamic loads as functions of the angle of attack (which is a function of pitch angle) are obtained. The pitch optimization problem is investigated by considering the maximum value problem of the instantaneous torque of a blade as a function of pitch angle. Dynamic pitch laws for HAWT blades with either symmetric or asymmetric airfoils are derived. Influences of parameters including inflow ratio, rotational speed, azimuth, and wind speed on torque coefficient and optimal pith angle are discussed.

환경관리주의 환경교육에 대한 비판적 고찰 - 원인규명에서 해결기제로의 전환을 위하여 - (A Critical Approach on Environmental Education Biased to Environmental Possibilism - From Clearing up the Cause to Problem-Solving Mechanism -)

  • 김태경
    • 한국환경교육학회지:환경교육
    • /
    • 제18권3호
    • /
    • pp.59-74
    • /
    • 2005
  • We can't deny Korean EE has basically developed on the basis of Environmental Possibilism (Environmental management or Reformism) in lots of aspects. I would show three representative proofs here, the first, the philosophy of Korean EE has been mainly focused on dichotomy of human-techno centrism and eco-centrism with no considering other alternative environmentalism since 4th Formal Curriculum, 1981. The second, simultaneously, the concept of EE has not distinguished from it of Science education. (Furthermore, unfortunately some says EE has been a part of Science education, although there should be many differences on its contextual aspect.) And the third one is that the limit of possibilism which market economists have worried, has scarcely mentioned in various kinds of EE-related teaching materials. Possibilism is basically likely to be accompanied by science and economics-oriented approach, and in this aspect this dichotomy, human-techno centrism and eco-centrism, has come from perspectives of Economical development process and over-addicted belief to Science. So it is enough to say that Korean EE has basically developed with biased to Environmental possibilism, in other words, biased to preference to it. And I'll critically focus on these two axes of possibilism, Science and Economics and its dichotomy. Of course, we should accept there are so many same parts in its contents between EE and Science, but we should know its contextual differences for triangular position of environmentalism suitable to EE and also overcome science-dependant approach to EE. Although science-dependant approach to EE and dichotomy could provide some tools for clearing up the causes of environmental problem, especially always it has insisted fundamental causes of environmental problem originated in human faults and over-use of eco-source or over-economic development, but now it is old-fashioned discourse, furthermore it come to have unavoidable limits in the debates of problem-solving mechanism to environmental problems. The paramount important thing is to supply the ways or thoughtful mechanism for solving or coordinating the Environmental problems, not just searching for cause of it. But scientific approach and its dichotomy based on possibilism have continuously born cause & effect in EE-related discourse. So there are so much needs to transfer from continuous bearing of cause & effect to constructive alternatives at least in environmentalism of EE. Traditionally, dichotomical division in EE Environmentalism, human-techno centrism and eco-centrism, couldn't have Provided any answers to our real society, it just gives us only cause & effects of Environmental problems. And also we can't find the description on the limits of capitalism market approach to Environmental problems especially in Korean EE text books, other teaching materials and its teaching-learning process, although market approach economist has been proved its fault beyond its functional merits as Environmental management tools. So we should introduce other alternative Environmental philosophy instead of Possibilism such as eco-socialism insisted by Schmacher M. and Boochin etc, or marxist-environmentalism for relative and comparative views to market-thought such as commodification. In this aspect we need to accept Oriental philosophy based on moderation(中庸) as new another alternatives with the reflection that we have recognized monism as representative Oriental philosophical environmentalism. Fundamentally monism has done its role with providing relative concepts to Dichotomy Enlightenment, but we can't say it has been core concept for understanding of oriental environmentalism, and we can't distinguish monism from oriental philosophy itself, just because oriental thought itself was basically monism. So conceptual difference should be recognized between EE and Science education in teaching-learning process on the basis of life-philosophy(Philosophie des Lebens) from epistemology. For this transformation, we should introduce existentialism in Science education, in other words, only existential Science education based on phenomenology or interpretivism can be EE. And simultaneously we need some ways for overcoming of scientific foundationalism which has been tradition making science not stand on existentialism, formulating and featuring of almost all of natural things and its phenomenon from after enlightenment in western world, but it has malfunctioned in fixing conception of science just into essentialism itself. And we also introduce integrated approach to science and society for EE like STS. Those are ways for overcoming of Environmental possibilism in EE.

  • PDF

ICNP의 후향적 개발방법에 의한 한국의 학교간호현상 (Development of School Health Nursing Phenomena in Korea by Retrospective Method of ICNP)

  • 김영임;양순옥;왕명자;김정남;김현숙;박태남;정미자;현혜진
    • 지역사회간호학회지
    • /
    • 제13권4호
    • /
    • pp.595-607
    • /
    • 2002
  • The objectives of this study were to identify the phenomena of school health nursing at schools in Korea and to contribute to building a school health domain of International Classification for Nursing Practice. A retrospective method was used in this study to develop ICNP during the period from July to October 200l. The procedure of the study involved choosing nursing phenomena using preliminary terms from the reports on the field of school health nursing practice documented by nursing students in 10 different nursing colleges. The detail procedures of the study were as follows. 1) Choosing nursing phenomena by using preliminary terms 2) Choosing the characteristics of school health nursing practice from the selected nursing phenomena 3) In order to make a consensus regarding the appropriate characteristics of phenomena. 15 study group members re-categorized the nursing phenomena through 5 times of cyber meetings and 3 times of formal meetings. 4) To verify each characteristic, 5 community nursing faculties and 25 school health nurses participated in the procedure to give scores on nursing characteristics. 5) Classification of the definite nursing phenomena and characteristics. Following the 5 step procedures, school health nursing phenomena were categorized into human and environmental domains. Human domains were classified into human behavioral and functional domains. Environmental domains were classified into physical and psychosocial domains. The essential characteristics of each phenomena were selected when it obtains the mean score of 3.0 or over at the related characteristics. The human behavioral domain consisted of 7 phenomena including risk for spinal disorder, inadequate dietary habit, inadequate weight control, smoking and substance abuse, inadequate stress management, inadequate sex related coping strategies and inadequate accident management. The human functional domain consisted of 6 phenomena including inadequate eye care and visual management, risk for respiratory disorder, inadequate dental health care, inappropriate infectious disease control, risk for gastrointestinal disorder, and lack of sexual identity. The physical environmental domain consisted of 6 phenomena including risk for incident at inside classroom, risk for incident at outside classroom, risk for incident around school, risk for exposure to hazardous facilities around school. inadequate garbage and disposal management, and inadequate physical environment for learning. The psychosocial domain included impaired social interaction at school. Each phenomenon was composed of 2 to 8 characteristics and all phenomena will include a total number of 85 characteristics. The phenomena of school health nursing in Korea partially confirmed school health architecture of ICNP. Further study on verification of school health nursing phenomena in Korea needs to be done to support the findings of this study through review of literature on nursing classifications or field studies.

  • PDF

분류된 천연유기물질을 이용한 막 오염 특성 평가 (Effect of Fractionated Organic Matter on Membrane Fouling)

  • 이병구;손희종;노재순;황영도;정철우;강임석
    • 대한환경공학회지
    • /
    • 제27권12호
    • /
    • pp.1321-1326
    • /
    • 2005
  • 낙동강 원수의 경우 소수성 물질이 43%, 친수성 물질이 39%, 반친수성 물질이 18%를 차지하고 있는 것으로 나타났으며, 소수성 물질을 세분화하여 조사한 결과 fulvic acid는 62%, humic acid는 38%로 나타났으며, 또한, 카르복실기는 64%, 페놀기는 36%를 차지하고 있는 것으로 나타났다. 친수성 물질을 세분화하여 조사한 결과 HPI-N이 44%, HPI-C가 56%를 차지하고 있었다. 친수성 유기물질 중 HPI-C에 비하여 HPI-N이 막 오염을 더욱 많이 유발하였으며, 소수성 유기물질에서는 HA가 FA에 비하여 막 오염을 더 많이 유발하였으며, 작용기에 따른 막 오염 현상을 살펴보면 카르복실기의 경우 페놀기에 비하여 투과 flux 감소가 크게 나타나고 있다. 공극의 크기가 커질수록 공극 속으로 전달되는 고분자 유기물이 많이 발생하며 이러한 고분자 유기물이 공극을 막아버리는 현상에 의하여 투과 flux 감소가 발생하는 것으로 나타났다. 또한 공극의 크기가 상대적으로 큰 막의 경우 투과되는 양이 공극이 작은 막 보다 상대적으로 많기 때문에 운전초기에 많은 양의 유기물이 막으로 전달되어 막의 표면과 공극에 흡착되어 막의 공극의 크기가 커짐에 따라 투과 flux 감소가 크게 나타났다.