• 제목/요약/키워드: Temperature inversion

검색결과 302건 처리시간 0.034초

A new method solving the temperature field of concrete around cooling pipes

  • Zhu, Zhenyang;Qiang, Sheng;Chen, Weimin
    • Computers and Concrete
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    • 제11권5호
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    • pp.441-462
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    • 2013
  • When using the conventional finite element method, a great number of grid nodes are necessary to describe the large and uneven temperature gradients in the concrete around cooling pipes when calculating the temperature field of mass concrete with cooling pipes. In this paper, the temperature gradient properties of the concrete around a pipe were studied. A new calculation method was developed based on these properties and an explicit iterative algorithm. With a small number of grid nodes, both the temperature distribution along the cooling pipe and the temperature field of the concrete around the water pipe can be correctly calculated with this new method. In conventional computing models, the cooling pipes are regarded as the third boundary condition when solving a model of concrete with plastic pipes, which is an approximate way. At the same time, the corresponding parameters have to be got by expensive experiments and inversion. But in the proposed method, the boundary condition is described strictly, and thus is more reliable and economical. And numerical examples were used to illustrate that this method is accurate, efficient and applicable to the actual engineering.

Extraction of Effective Carrier Velocity and Observation of Velocity Overshoot in Sub-40 nm MOSFETs

  • Kim, Jun-Soo;Lee, Jae-Hong;Yun, Yeo-Nam;Park, Byung-Gook;Lee, Jong-Duk;Shin, Hyung-Cheol
    • JSTS:Journal of Semiconductor Technology and Science
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    • 제8권2호
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    • pp.115-120
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    • 2008
  • Carrier velocity in the MOSFET channel is the main driving force for improved transistor performance with scaling. We report measurements of the drift velocity of electrons and holes in silicon inversion layers. A technique for extracting effective carrier velocity which is a more accurate extraction method based on the actual inversion charge measurement is used. This method gives more accurate result over the whole range of $V_{ds}$, because it does not assume a linear approximation to obtain the inversion charge and it does not limit the range of applicable $V_{ds}$. For a very short channel length device, the electron velocity overshoot is observed at room temperature in 37 nm MOSFETs while no hole velocity overshoot is observed down to 36 nm. The electron velocity of short channel device was found to be strongly dependent on the longitudinal field.

AN ELECTROMAGNETIC FREE CONVECTION FLOW OF A MICROPOLAR FLUID WITH RELAXATION TIME

  • Zakaria, M.
    • Journal of applied mathematics & informatics
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    • 제8권2호
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    • pp.539-550
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    • 2001
  • In the present investigation, we study the influence of a transverse magnetic field through a porous medium. Laplace transform techniques are used to derive the solution in the Laplace transform domain. The inversion process is carried out using a numerical method based on Fourier series expansions. Numerical computations for the temperature, the microrotation and the velocity distributions as well as for the induced magnetic and electric fields and carried out and represented graphically.

아닐링법에 의한 지구물리자료의 역산 (Inversion of Geophysical Data via Simulated Annealing)

  • 김희준
    • 자원환경지질
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    • 제28권3호
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    • pp.305-309
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    • 1995
  • There is a deep and useful connection between thermodynamics (the behavior of systems with many degrees of freedom in thermal equilibrium at a finite temperature) and combinational or continuous optimization (finding the minimum of a given multiparameter function). At the heart of the method of simulated annealing is an analogy with the way that liquids freeze and crystallize, or metals cool and anneal. This paper provides a detailed description of simulated annealing. Although computationaly intensive, when it is carefully implemented, simulated annealing is found to give superior results to more traditional methods of nonlinear optimization.

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Periodic domain formation in $>LiNbO_3$ single crystals during growth

  • Park, Jong-Koen
    • 한국결정성장학회:학술대회논문집
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    • 한국결정성장학회 1998년도 PROCEEDINGS OF THE 14TH KACG TECHNICAL MEETING AND THE 5TH KOREA-JAPAN EMGS (ELECTRONIC MATERIALS GROWTH SYMPOSIUM)
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    • pp.23-26
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    • 1998
  • The domain formation phenomena of {{{{ { LiLbO}_{ 3} }}}} crystals was investigated and the method for the periodic domain formation in {{{{ { LiLbO}_{ 3} }}}} single crystals during growth was proposed in this study. The strees-induced domain formation mechanism was proposed and explained. The strong piezoelectric effect of{{{{ { LiLbO}_{ 3} }}}} at elevated temperature would be the direct driving force for the inversion of the tensile component of the internal stresses can inverse the original direction of the spontaneous polarization.

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비대칭 아크 플라즈마의 온도 분포 측정 (Temperature Measurement of asymmetric arc plasma by abel inversion)

  • 조영태;나석주
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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    • pp.109-111
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    • 2004
  • 아크 플라즈마의 온도 분포를 측정하는 방법으로 개발된 CCD 카메라를 이용한 온도 측정 방법을 비대칭 플라즈마의 온도 분포 측정에 적용하기 위해 비대칭 플라즈마의 데이터 변환에 이용 가능한 아벨 역산 방법을 개발하였다. 비대칭 플라즈마 중 V-groove 상의 아크는 타원형의 플라즈마로 볼 수가 있으므로 타원형의 단면을 가지는 플라즈마에 대해 온도 측정을 수행하고 그 결과로서 모재로 전달되는 아크의 열속(heat flux)의 분포를 예측 할 수 있었다.

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Hysteretic behavior in polymer stabilized ferroelectric liquid crystal

  • Lee, Ji-Hoon;Lim, Tong-Kun
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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    • pp.334-337
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    • 2005
  • We have found that the hysteretic behavior of a polymer stabilized ferroelectric liquid crystal system coincides with Blinov et. al's model qualitatively. The hysteresis inversion frequency could be promoted up to 7000 Hz by connecting external capacitor and resistor in serial. In addition, the influence of temperature and the amplitude of the applied field on hysteresis-free switching of the cell could be minimized.

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Skin compatible Microemulsions obtained by a new PIT -Nano- Technology Approach

  • Jorg Schreiber;Ulrich Kux;Anja Eitrich;Wittern, Klaus-Peter;Yvonne Cierpisz
    • 대한화장품학회:학술대회논문집
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    • 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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    • pp.392-404
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    • 2003
  • A new technology to achieve o/w microemulsions allows the formulation of transparent products with low surfactant content. The PIT Nanotechnology approach gives cosmetic/pharmaceutical o/w microemulsions in one step with a broad variety of surfactants, cosurfactants and oil phases.

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