• Title/Summary/Keyword: Integral transforms

Search Result 127, Processing Time 0.021 seconds

Computation of Green's Tensor Integrals in Three-Dimensional Magnetotelluric Modeling Using Integral Equations (적분방정식을 사용한 3차원 MT 모델링에서의 텐서 그린 적분의 계산)

  • Kim, Hee Joon;Lee, Dong Sung
    • Economic and Environmental Geology
    • /
    • v.27 no.1
    • /
    • pp.41-47
    • /
    • 1994
  • A fast Hankel transform (FHT) algorithm (Anderson, 1982) is applied to numerical evaluation of many Green's tensor integrals encountered in three-dimensional electromagnetic modeling using integral equations. Efficient computation of Hankel transforms is obtained by a combination of related and lagged convolutions which are available in the FHT. We express Green's tensor integrals for a layered half-space, and rewrite those to a form of related functions so that the FHT can be applied in an efficient manner. By use of the FHT, a complete or full matrix of the related Hankel transform can be rapidly and accurately calculated for about the same computation time as would be required for a single direct convolution. Computing time for a five-layer half-space shows that the FHT is about 117 and 4 times faster than conventional direct and multiple lagged convolution methods, respectively.

  • PDF

Elastic Wave Propagation in Monoclinic System Due to Harmonic Line Load

  • Kim, Yong-Yun
    • The Journal of the Acoustical Society of Korea
    • /
    • v.17 no.2E
    • /
    • pp.47-52
    • /
    • 1998
  • An analysis of dynamic responses is carried out on monoclinic anisotropic system due to a buried harmonic line source. The load is in the form of a normal stress acting along an arbitrary axis on the plane of symmetry within the orthotropic materials: In case that the line load is acting along the symmetry axis normal to the plane of symmetry, plane wave equation is coupled with verital shear wave and longitudinal wave. However, if the line load is acting along an arbitrary axis normal to the plane of symmetry, plane wave equation is coupled with vertical shear wave, longitudinal wave and horizontal shear wave. We first considered the equation of motion in a reference coordinate system, where the line load is coincident with a symmetry axis of the orthotropic material. Then the equation of motion is transformed into one with respect to general coordinate system with azimuthal angle by using transformation tensor. Plane wave solutions of monoclinic systems are derived for infinite media. Finally complete solutions for the plane harmonic wave are obtained by calculating the inverse of the integral transforms, in which bulk wave poles are avoided by deforming the contour of the integration to the complex plane. Numerical results for examples of orthotropic material belonging to monoclinic symmetry are demonstrated.

  • PDF

ON THE ANALOGS OF BERNOULLI AND EULER NUMBERS, RELATED IDENTITIES AND ZETA AND L-FUNCTIONS

  • Kim, Tae-Kyun;Rim, Seog-Hoon;Simsek, Yilmaz;Kim, Dae-Yeoul
    • Journal of the Korean Mathematical Society
    • /
    • v.45 no.2
    • /
    • pp.435-453
    • /
    • 2008
  • In this paper, by using q-deformed bosonic p-adic integral, we give $\lambda$-Bernoulli numbers and polynomials, we prove Witt's type formula of $\lambda$-Bernoulli polynomials and Gauss multiplicative formula for $\lambda$-Bernoulli polynomials. By using derivative operator to the generating functions of $\lambda$-Bernoulli polynomials and generalized $\lambda$-Bernoulli numbers, we give Hurwitz type $\lambda$-zeta functions and Dirichlet's type $\lambda$-L-functions; which are interpolated $\lambda$-Bernoulli polynomials and generalized $\lambda$-Bernoulli numbers, respectively. We give generating function of $\lambda$-Bernoulli numbers with order r. By using Mellin transforms to their function, we prove relations between multiply zeta function and $\lambda$-Bernoulli polynomials and ordinary Bernoulli numbers of order r and $\lambda$-Bernoulli numbers, respectively. We also study on $\lambda$-Bernoulli numbers and polynomials in the space of locally constant. Moreover, we define $\lambda$-partial zeta function and interpolation function.

Non-stationary vibration and super-harmonic resonances of nonlinear viscoelastic nano-resonators

  • Ajri, Masoud;Rastgoo, Abbas;Fakhrabadi, Mir Masoud Seyyed
    • Structural Engineering and Mechanics
    • /
    • v.70 no.5
    • /
    • pp.623-637
    • /
    • 2019
  • This paper analyzes the non-stationary vibration and super-harmonic resonances in nonlinear dynamic motion of viscoelastic nano-resonators. For this purpose, a new coupled size-dependent model is developed for a plate-shape nano-resonator made of nonlinear viscoelastic material based on modified coupled stress theory. The virtual work induced by viscous forces obtained in the framework of the Leaderman integral for the size-independent and size-dependent stress tensors. With incorporating the size-dependent potential energy, kinetic energy, and an external excitation force work based on Hamilton's principle, the viscous work equation is balanced. The resulting size-dependent viscoelastically coupled equations are solved using the expansion theory, Galerkin method and the fourth-order Runge-Kutta technique. The Hilbert-Huang transform is performed to examine the effects of the viscoelastic parameter and initial excitation values on the nanosystem free vibration. Furthermore, the secondary resonance due to the super-harmonic motions are examined in the form of frequency response, force response, Poincare map, phase portrait and fast Fourier transforms. The results show that the vibration of viscoelastic nanosystem is non-stationary at higher excitation values unlike the elastic ones. In addition, ignoring the small-size effects shifts the secondary resonance, significantly.

DIGITAL TECHNOLOGIES AND RANKINGS AS TOOLS OF THE COMPETITIVENESS IN THE EDUCATIONAL SERVICES MARKET

  • Djakona, Antonina;Lavrov, Ruslan;Anisimova, Liudmyla;Koval, Oksana;Polkhovska, Maryna;Shumaieva, Svitlana
    • International Journal of Computer Science & Network Security
    • /
    • v.21 no.11
    • /
    • pp.49-58
    • /
    • 2021
  • Globalization of higher education deepens the competition in the global educational services market. Competition between higher education institutions is based on the use of a wide range of activities and tools that are constantly evolving and becoming more complex. Digitalization significantly transforms the approaches to competition between universities in educational, research and marketing activities. Digital technologies are becoming an integral part of this competition. In addition, in the current conditions of globalization of the scientific and educational space, numerous rankings of universities have become an important tool of the competition; the most significant rankings of universities are as follows: Academic Ranking of World Universities (China), Times Higher Education Rankings of Universities (Great Britain), Webometrics (Spain). In the article, the key principles of the formation of world rankings of universities are analyzed, the main sources of information resources for their compilation are determined. The authors have concluded that the improvement of the position of educational institutions in the world rankings of universities should be implemented within the framework of the state educational policy. The key positive effects of universities due to increasing the competitiveness level of the national higher education system are specified.

A "Dynamic Form-Finding" Approach to Environmental-Performance Building Design

  • Yao, Jia-Wei;Lin, Yu-Qiong;Zheng, Jing-Yun;Yuan, Philip F.
    • International Journal of High-Rise Buildings
    • /
    • v.7 no.2
    • /
    • pp.145-151
    • /
    • 2018
  • Newly-designed high-rise buildings, both in China and abroad, have demonstrated new innovations from the creative concept to the creative method. from the creative concept to the creative method. At the same time, digital technology has enabled more design freedom in the vertical dimension. "Twisting" has gradually become the morphological choice of many city landmark buildings in recent years. The form seems more likely to be driven by the interaction of aesthetics and structural engineering. Environmental performance is often a secondary consideration; it is typically not simulated until the evaluation phase. Based on the research results of "DigitalFUTURE Shanghai 2017 Workshop - Wind Tunnel Visualization", an approach that can be employed by architects to design environmental-performance buildings during the early stages has been explored. The integration of a dynamic form-finding approach (DFFA) and programming transforms the complex relationship between architecture and environment into a dialogue of computer language and dynamic models. It allows the design to focus on the relationship between morphology and the surrounding environment, and is not limited to the envelope form itself. This new concept of DFFA in this research consists of three elements: 1) architectural form; 2) integration of wind tunnel and dynamic models; and 3) environmental response. The concept of wind tunnel testing integrated with a dynamic model fundamentally abandons the functional definition of the traditional static environment simulation analysis. Instead it is driven by integral environmental performance as the basic starting point of morphological generation.

Autopoietic Machinery and the Emergence of Third-Order Cybernetics (자기생산 기계 시스템과 3차 사이버네틱스의 등장)

  • Lee, Sungbum
    • Cross-Cultural Studies
    • /
    • v.52
    • /
    • pp.277-312
    • /
    • 2018
  • First-order cybernetics during the 1940s and 1950s aimed for control of an observed system, while second-order cybernetics during the mid-1970s aspired to address the mechanism of an observing system. The former pursues an objective, subjectless, approach to a system, whereas the latter prefers a subjective, personal approach to a system. Second-order observation must be noted since a human observer is a living system that has its unique cognition. Maturana and Varela place the autopoiesis of this biological system at the core of second-order cybernetics. They contend that an autpoietic system maintains, transforms and produces itself. Technoscientific recreation of biological autopoiesis opens up to a new step in cybernetics: what I describe as third-order cybernetics. The formation of technoscientific autopoiesis overlaps with the Fourth Industrial Revolution or what Erik Brynjolfsson and Andrew McAfee call the Second Machine Age. It leads to a radical shift from human centrism to posthumanity whereby humanity is mechanized, and machinery is biologized. In two versions of the novel Demon Seed, American novelist Dean Koontz explores the significance of technoscientific autopoiesis. The 1973 version dramatizes two kinds of observers: the technophobic human observer and the technology-friendly machine observer Proteus. As the story concludes, the former dominates the latter with the result that an anthropocentric position still works. The 1997 version, however, reveals the victory of the techno-friendly narrator Proteus over the anthropocentric narrator. Losing his narrational position, the technophobic human narrator of the story disappears. In the 1997 version, Proteus becomes the subject of desire in luring divorcee Susan. He longs to flaunt his male egomaniac. His achievement of male identity is a sign of technological autopoiesis characteristic of third-order cybernetics. To display self-producing capabilities integral to the autonomy of machinery, Koontz's novel demonstrates that Proteus manipulates Susan's egg to produce a human-machine mixture. Koontz's demon child, problematically enough, implicates the future of eugenics in an era of technological autopoiesis. Proteus creates a crossbreed of humanity and machinery to engineer a perfect body and mind. He fixes incurable or intractable diseases through genetic modifications. Proteus transfers a vast amount of digital information to his offspring's brain, which enables the demon child to achieve state-of-the-art intelligence. His technological editing of human genes and consciousness leads to digital standardization through unanimous spread of the best qualities of humanity. He gathers distinguished human genes and mental status much like collecting luxury brands. Accordingly, Proteus's child-making project ultimately moves towards technologically-controlled eugenics. Pointedly, it disturbs the classical ideal of liberal humanism celebrating a human being as the master of his or her nature.