• Title, Summary, Keyword: non-symmetry

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Solution of Eigenproblems for Non-proportional Damping Systems by Lanczos Method (Lanczos 방법에 의한 비비례 감쇠 시스템의 고유치 해석)

  • 김만철;정형조;오주원;이인원
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.283-290
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    • 1998
  • A solution method is presented to solve the eigenproblem arising in tile dynamic analysis of non-proportional damping systems with symmetric matrices. The method is based on tile use of Lanczos method to generate a Krylov subspace of trial vectors, witch is then used to reduce a large eigenvalue problem to a much smaller one. The method retains the η order quadratic eigenproblem, without the need to the method of matrix augmentation traditionally used to cast the problem as a linear eigenproblem of order 2n. In the process, the method preserves tile sparseness and symmetry of the system matrices and does not invoke complex arithmetics, therefore, making it very economical for use in solving large problems. Numerical results are presented to demonstrate the efficiency and accuracy of the method.

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The Crystal Structure of Fenbufen, 3-(4-biphenylylcarbonyl)propionic acid ($C_{16}H_{14}O_3$), A Non-steroidal Antiinflammatory Agent

  • Kim, Yang-Bae;Park, Il-Yeong;Park, Yang-Hwan
    • Archives of Pharmacal Research
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    • v.11 no.2
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    • pp.127-133
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    • 1988
  • The crystal structure of fenbufen was determined by X-ray diffraction techniuques. The compound was recrystallized in orthorhombic crystal system, space group $Pca2_1$ a = 31. 918(10), b = 5.550 (2), c = 15.078 (9) ${\AA}, D_m$= $1.26, {\D_x$= 1.264 g/$\textrm{cm}^3$, and Z = 8. The structure was solved by direct methods and refined by least squares procedure to the final R value of 0.051 for 1780 independent reflections. Two molecules in the asymmetric unit are related by a pseudo center of symmetry and dimerized via O-H...O hydrogen bonds. The carbonyl group attached to the phenyl ring is nearly coplanar to the ring. In the crystal the molecules are arranged in paralle stacks in the a direction.

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PRIMORDIAL BLACKHOLE AS A SEED FOR THE COSMIC MAGNETIC FIELD

  • LA DAIL;PARK CHANGBOM
    • Journal of The Korean Astronomical Society
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    • v.29 no.2
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    • pp.83-91
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    • 1996
  • We present a model that rotating primordial blackholes(PBHs) produced at the end of inflation generate the random, non-oriented primordial magnetic field. PBHs are copiously produced as the Universe completes the cosmic phase transition via bubble nucleation and tunneling processes in the extended inflation hypothesis. The PBHs produced acquire angular momentum through the mutual tidal gravitational interaction. For PBHs of mass less than 1013g, one can show that the evaporation (photon) luminosity of PBHs exceeds the Eddington limit. Thus throughout the lifetime of the rotating PBH, radiation flow from the central blackhole along the Kerr-geodesic exerts torque to ambient plasma. In the process similar to the Bierman's battery mechanism electron current reaching up to the horizon scale is induced. For PBHs of Grand Unified Theories extended inflation with the symmetry breaking temperature of $T_{GUT}\;\~\;10^{10}$ GeV, which evaporate near decoupling, we find that they generate random, non-oriented magnetic fields of $\~10^{-11}G$ on the last-scattering surface on (the present comoving) scales of $\~O(10)Mpc$.

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MONTE-CARLO SIMULATION OF NEUTRON STAR ORBITS IN THE GALAXY

  • TAANI, ALI
    • Publications of The Korean Astronomical Society
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    • v.30 no.2
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    • pp.583-584
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    • 2015
  • In this paper, the numerical results concerning different orbits of a 3D axisymmetric non-rotating galactic potential are presented. We use $Paczy{\acute{n}}ski^{\prime}s$ gravitational potential with different birth velocity distributions for the isolated old Neutron Star (NS) population. We note some smooth non-constant segments corresponding to regular orbits as well as the characterization of their chaoticity. This is strongly related to the effect of different kick velocities due to supernovae mass-loss and natal kicks to the newly-formed NS. We further confirm that the dynamical motion of the isolated old NSs in the gravitational field becomes obvious, with some significant diffraction in the symmetry of their orbital characteristics.

Asymmetric flows of non-Newtonian fluids in symmetric stenosed artery

  • Hun Jung;Park, Jong-Wook;Park, Chan-Guk
    • Korea-Australia Rheology Journal
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    • v.16 no.2
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    • pp.101-108
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    • 2004
  • The hemodynamics behavior of the blood flow is influenced by the presence of the arterial stenosis. If the stenosis is present in an artery, normal blood flow is disturbed. In the present study, the characteristics of pulsatile flow in the blood vessel with stenosis are investigated by the finite volume method. For the validation of numerical model, the computation results are compared with the experimental ones of Ojha et al. in the case of 45% stenosis with a trapezoidal profile. Comparisons between the measured and the computed velocity profiles are favorable to our solutions. Finally, the effects of stenosis severity and wall shear stress are discussed in the present computational analysis. It can be seen, where the non-dimensional peak velocity is displayed for all the stenosis models at a given severity of stenosis, that it is exponentially increased. Although the stenosis and the boundary conditions are all symmetric, the asymmetric flow can be detected in the more than 57% stenosis. The instability by a three-dimensional symmetry-breaking leads to the asymmetric separation and the intense swirling motion downstream of the stenosis.

Approximate Analysis of MAC Protocol with Multiple Self-tokens in a Slotted Ring

  • Sakuta, Makoto;Sasase, Iwao
    • Journal of Communications and Networks
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    • v.5 no.3
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    • pp.249-257
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    • 2003
  • Ring networks are very commonly exploited among local area and metropolitan area networks (LAN/MAN), whereas cells or small fixed-size packets are widely used in synchronized ring networks. In this paper, we present an analytical method for evaluating the delay-throughput performance of a MAC protocol with multiple self-tokens in a slotted ring network under uniform traffic. In our analysis, we introduce the stationary probability, which indicates the number of packets in a node. Also, it is assumed that each node has a sufficiently large amount of self-tokens, and a slotted ring has the symmetry. The analytical results with respect to delay-throughput performance have similar values to computer simulated ones. Furthermore, in order to achieve fair access under non-uniform traffic, we propose an adaptive MAC protocol, where the number of self-tokens in a node dynamically varies, based on the number of packets transmitted within a specified period. In the proposed protocol, when the number of packets transmitted by a node within a specified period is larger than a specified threshold, the node decreases the number of self-tokens in a per-node distributed method. That results in creating free slots in the ring, thus all nodes can obtain an equal opportunity to transmit into the ring. Performance results obtained by computer simulation show that our proposed protocol can maintain throughput fairness under non-uniform traffic.

Gait Asymmetry in Children with Down Syndrome (다운증후군 아동들의 보행 비대칭성 연구)

  • Lim, Bee-Oh;Han, Dong-Ki;Seo, Jung-Suk;Eun, Seon-Deok;Kwon, Young-Hoo
    • Korean Journal of Sport Biomechanics
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    • v.16 no.2
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    • pp.145-151
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    • 2006
  • A large interindividual variability and some abnormally kinematic patterns at the lower extremity were the main features of the gait in children with Down syndrome. The purposes of this study were to investigate the gait asymmetry and biomechanical difference between dominant leg and non dominant leg in children with Down syndrome. Seven boys with Down Syndrome(age: $120{\pm}0.9yrs$, weight $34.4{\pm}8.4kg$, leg length: $68.7{\pm}5.0cm$) participated in this study. A 10.0 m ${\times}$ 1.3 m walkway with a firm dark surface was built and used for data collection. Three-dimensional motion analyses were performed to obtain the joint angles and range of motions. The vertical ground reaction forces(%BW) and impulses($%BW{\cdot}s$) were measured by two force plates embedded in the walkway. Asymmetry indices between the legs were computed for all variables. After decision the dominant leg and the non dominant leg with max hip abduction angle, paired samples t-test was employed for selected kinematic and ground reaction force variables to analyze the differences between the dominant leg and the non dominant leg. The max hip abduction angle during the swing phase showed most asymmetry, while the knee flexion angle at initial contact showed most symmetry in walking and running. The dominant leg showed more excessive abduction of hip in the swing phase and more flat-footed contact than the non dominant leg. Vertical peak force in running showed more larger than those of in walking, however, vertical impulse showed more small than walking due to decrease of support time. In conclusion, the foot of dominant leg contact more carefully than those of non dominant leg. And also, there are no significant difference between the dominant leg and the non dominant leg in kinematic variables and ground reaction force due to large interindividual variability.

Effects of Eu3+ and Tb3+ Activator Ions on the Properties of SrSnO3 Phosphors (Eu3+와 Tb3+ 활성제 이온이 SrSnO3 형광체의 특성에 미치는 영향)

  • Kim, Jung Dae;Cho, Shinho
    • Korean Journal of Materials Research
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    • v.24 no.9
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    • pp.469-473
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    • 2014
  • $SrSnO_3$ phosphor powders were synthesized with two different contents of activator ions $Eu^{3+}$ and $Tb^{3+}$ using the solid-state reaction method. The structural, morphological, and optical properties of the phosphors were investigated using X-ray diffractometry, field-emission scanning electron microscopy, and fluorescence spectrophotometry, respectively. All the phosphors showed a cubic structure, irrespective of the type and the content ratio of activator ions. For $Eu^{3+}$-doped $SrSnO_3$ phosphors, the intensity of the 620 nm red emission spectrum resulting from the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ was stronger than that of the 595 nm orange emission signal due to the $^5D_0{\rightarrow}^7F_1$ transition in the range 0.01-0.05 mol of $Eu^{3+}$, but the ratio of the intensity was reversed in the range 0.10-0.20 mol of $Eu^{3+}$. The variation in the emission intensity indicates that the site symmetry of the $Eu^{3+}$ ions around the host crystal was changed from non-inversion symmetry to inversion. For the $Tb^{3+}$-doped $SrSnO_3$ phosphors under excitation at 281 nm, one strong green emission band at 550 nm and several weak bands were observed. These results suggest that the optimum red and green emission signals can be realized when the activator ion content for $Eu^{3+}$- or $Tb^{3+}$-doped $SrSnO_3$ phosphors is 0.20 mol and 0.15 mol, respectively.

Range Detection of Wa/Kwa Parallel Noun Phrase using a Probabilistic Model and Modification Information (확률모형과 수식정보를 이용한 와/과 병렬사구 범위결정)

  • Choi, Yong-Seok;Shin, Ji-Ae;Choi, Key-Sun
    • Journal of KIISE:Software and Applications
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    • v.35 no.2
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    • pp.128-136
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    • 2008
  • Recognition of parallel structure at early stage of sentence parsing can reduce the complexity of parsing. In this paper, we propose an unsupervised language-independent probabilistic model for recongition of parallel noun structures. The proposed model is based on the idea of swapping constituents, which replies the properties of symmetry (two or more identical constituents are repeated) and of reversibility (the order of constituents is inter-changeable) in parallel structures. The non-symmetric patterns that cannot be captured by the general symmetry rule are resolved additionally by the modifier information. In particular this paper shows how the proposed model is applied to recognize Korean parallel noun phrases connected by "wa/kwa" particle. Our model is compared with other models including supervised models and performs better on recongition of parallel noun phrases.

Photoluminescence Properties of BiNbO4:RE3+ (RE = Dy, Eu, Sm, Tb) Phosphors (BiNbO4:RE3+ (RE = Dy, Eu, Sm, Tb) 형광체의 광학 특성)

  • Lee, Sangwoon;Cho, Shinho
    • Journal of the Korean institute of surface engineering
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    • v.50 no.3
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    • pp.206-211
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    • 2017
  • $BiNbO_4:RE^{3+}$ (RE = Dy, Eu, Sm, Tb) phosphors were prepared by solid-state reaction at $1100^{\circ}C$ and their structural, photoluminescent, and morphological properties were investigated. XRD patterns exhibited that all the synthesized phosphors exhibited a triclinic system with a dominant (210) diffraction peak, irrespective of the type of activator ions. The surface morphologies of rare-earth-ion-doped $BiNbO_4$ phosphors were found to depend strongly on the type of activator ions. The $Eu^{3+}$ and $Dy^{3+}$ doped $BiNbO_4$ phosphors revealed a strong red (613 nm) emission resulting from the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ and a dominant yellow (575 nm) emission originating from the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transition of $Dy^{3+}$ respectively, which were the electric dipole transitions, indicating that the activator ions occupy sites of non-inversion symmetry in the $BiNbO_4$ phosphor. The main reddish-orange emission spectra of $Sm^{3+}$-doped $BiNbO_4$ phosphors were due to the $^4G_{5/2}{\rightarrow}^6H_{7/2}$ (607 nm) magnetic dipole transition, indicating that the $Sm^{3+}$ ions were located at inversion symmetry sites in the $BiNbO_4$ host lattice. As for $Tb^{3+}$-doped phosphors, green emission was obtained under excitation at 353 nm and its CIE chromaticity coordinates were (0.274, 0.376). These results suggest that multicolor emission can be achieved by changing the type of activator ions incorporated into the $BiNbO_4$ host crystal.