• 제목/요약/키워드: Complex numbers

검색결과 444건 처리시간 0.028초

A NOTE ON GENOCCHI-ZETA FUNCTIONS

  • Park, Kyoung-Ho
    • 호남수학학술지
    • /
    • 제31권3호
    • /
    • pp.399-405
    • /
    • 2009
  • In this paper, we study the Genoochi-zeta functions which are entire functions in whole complex s-plane these zeta functions have the values of the Genocchi numbers and the Genoochi polynomials at negative integers respectively. That is ${\zeta}_G(1-k)={\frac{G_k}{k}}$ and ${\zeta}_G(1-k,x)={\frac{G_k(x)}{k}}$.

연속섬유강화 플라스틱 복합재료의 반구형 압축성형성에 관한 연구 (A Study on the Hemisphere-Type Compression Molding for Continous Fiber-Reinforced Polymeric Composites)

  • 임용진;오영준;김이곤
    • 한국복합재료학회:학술대회논문집
    • /
    • 한국복합재료학회 1999년도 추계학술발표대회 논문집
    • /
    • pp.149-153
    • /
    • 1999
  • During a hemisphere-type compression molding, the wrinkles are caused by complex stress condition. It is very important to clarify the degree of wrinkles in order to have good products. In this paper, the effects of numbers of needling and initial area on the degree of wrinkles are studied. the degree of wrinkle is expressed as nonhomogeneity.

  • PDF

Truncated Complex Moment Problem with Data in a Circle

  • Lee, Sang-Hun;Sim, Jung-Hui
    • Kyungpook Mathematical Journal
    • /
    • 제45권2호
    • /
    • pp.241-247
    • /
    • 2005
  • Let ${\gamma}{\equiv}\left{{\gamma}_{ij}\right}(0{\leq}i+j{\leq}2n)$ be a collection of complex numbers with ${\gamma}_{00}>0$ and ${\gamma}_{ji}={\bar{\gamma}}_{ij}$. The truncated complex moment problem for ${\gamma}$ entails finding a positive Borel measure ${\mu}$ supported in the complex plane ${\mathbb{C}}$ such that ${\gamma}_{ij}={\int}{\bar{z}}^{i}z^jd{\mu}(z)(0{\leq}i+j{\leq}2n)$. We solve this truncated moment problem with data in a circle and discuss the behavior of data in an extended moment matrix.

  • PDF

등온가열 수평원관내 융해과정동안의 열적 불안정성 (Thermal instability during the melting process in an isothermally heated horizontal cylinder)

  • 정재동;유호선;이준식
    • 대한기계학회논문집B
    • /
    • 제20권6호
    • /
    • pp.2046-2056
    • /
    • 1996
  • The constrained melting inside an isothermally heated horizontal cylinder has been repeatedly investigated in many studies only for the moderate Rayleigh numbers. This study extends the range of Rayleigh numbers to systematically investigate the transition during melting processes, especially focusing on the complex multi-cellular flow pattern and thermal instability. The enthalpy-porosity formulation, with appropriate source terms to account for the phase change, is employed. For low Rayleigh numbers, initially developed single-cell base flow keeps the flow stable. For moderate Rayleigh numbers, even small disturbances in balance between thermal buoyance force and viscous force result in branched flow structure. For high Rayleight numbers, Benard type convection is found to develop within a narrow gap between thee wall and the unmelted solid. The marginal Rayleigh number and the corresponding wave number are in excellent agreement with those from linear stability theory.

ON NONSINGULAR EMBRY QUARTIC MOMENT PROBLEM

  • Li, Chungji;Sun, Xiaoyun
    • 대한수학회보
    • /
    • 제44권2호
    • /
    • pp.337-350
    • /
    • 2007
  • Given a collection of complex numbers ${\gamma}{\equiv}\{{\gamma}ij\}$ $(0{\leq}i+j{\leq}2n,\;|i-j|{\leq}n)$ with ${\gamma}00>0\;and\;{\gamma}ji=\bar{\gamma}ij$, we consider the moment problem for ${\gamma}$ in the case of n=2, which is referred to Embry quartic moment problem. In this note we give a partial solution for the nonsingular case of Embry quartic moment problem.

Complex Shaped PM-parts by Warm Flow Compaction Process

  • Veltl, Georg;Petzoldt, Frank
    • 한국분말야금학회:학술대회논문집
    • /
    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
    • /
    • pp.203-204
    • /
    • 2006
  • There is an increasing demand for PM-processes with the capability to produce parts of higher complexity than with conventional press and sinter technology in high production numbers. Warm-flow-compaction (WFC) makes use of improved flowability of powders when blended in an appropriate ratio with fine powder fractions and lubricating binders. Here the process is shown with examples of PM-Steels. General features possible with the process like pressing of undercuts and threaded bores are shown.

  • PDF

코팅 조건에 따른 BST 박막의 표면 이미지 특성 (The Surface Image Properties of BST Thin Film by Depositing Conditions)

  • 홍경진;기현철;오수홍;조재철
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
    • /
    • pp.107-110
    • /
    • 2002
  • The optical memory devices of BST thin films to composite $(Ba_{0.7}\;Sr_{0.3})TiO_{3}$ using sol-gel method were fabricated by changing of the depositing layer number on $Pt/Ti/SiO_{2}/Si$ substrate. The structural properties of optical memory devices to be ferroelectric was investigated by fractal analysis and 3-dimension image processing. The thickness of BST thin films at each coating numbers 3, 4 and 5 times was $2500[\AA]$, $3500[\AA]$ and $3800[\AA]$. BST thin films exhibited the most pronounced grain growth. The surface morphology image was roughness with coating numbers. The thin films increasing with coating numbers shows a more textured and complex configuration.

  • PDF

A Fuzzy TOPSIS Approach Based on Trapezoidal Numbers to Material Selection Problem

  • Celik, Erkan;Gul, Muhammet;Gumus, Alev Taskin;Guneri, Ali Fuat
    • Journal of Information Technology Applications and Management
    • /
    • 제19권3호
    • /
    • pp.19-30
    • /
    • 2012
  • Material selection is a complex problem in the design and development of products for diverse engineering applications. This paper is aimed to present a fuzzy decision making approach to deal with the material selection in engineering design problems. A fuzzy multi criteria decision-making model is proposed for solving the material selection problem. The proposed model makes use of fuzzy TOPSIS (Technique for Order reference by Similarity to Ideal Solution) with trapezoidal numbers for evaluating the criteria and ranking the alternatives. And result is compared with fuzzy VIKOR (VlseKriterijumska Optimizacija I Kompromisno Resenje in Serbian, means Multi criteria Optimisation and Compromise Solution) which is proposed by Jeya Girubha and Vinodh [2012]. The present paper is aimed to also improve literature of fuzzy decision making for material selection problem.