• Title, Summary, Keyword: directionality

Search Result 230, Processing Time 0.033 seconds

Analysis of hurricane directionality effects using event-based simulation

  • Huang, Zhigang;Rosowsky, David V.
    • Wind and Structures
    • /
    • v.3 no.3
    • /
    • pp.177-191
    • /
    • 2000
  • This paper presents an approach for evaluating directionality effects for both wind speeds and wind loads in hurricane-prone regions. The focus of this study is on directional wind loads on low-rise structures. Using event-based simulation, hurricane directionality effects are determined for an open-terrain condition at various locations in the southeastern United States. The wind speed (or wind load) directionality factor, defined as the ratio of the N-year mean recurrence interval (MRI) wind speed (or wind load) in each direction to the non-directional N-year MRI wind speed (or wind load), is less than one but increases toward unity with increasing MRI. Thus, the degree of conservatism that results from neglecting directionality effects decreases with increasing MRI. It may be desirable to account for local exposure effects (siting effects such as shielding, orientation, etc.) in design. To account for these effects in a directionality adjustment, the factor described above for open terrain would need to be transformed to other terrains/exposures. A "local" directionality factor, therefore, must effectively combine these two adjustments (event directionality and siting or local exposure directionality). By also considering the direction-specific aerodynamic coefficient, a direction-dependent wind load can be evaluated. While the data necessary to make predictions of directional wind loads may not routinely be available in the case of low-rise structures, the concept is discussed and illustrated in this paper.

Automatic Conversion of Triangular Meshes Into Quadrilateral Meshes with Directionality

  • Itoh, Takayuki;Shimada, Kenji
    • International Journal of CAD/CAM
    • /
    • v.1 no.1
    • /
    • pp.11-21
    • /
    • 2002
  • This paper presents a triangular-to-quadrilateral mesh conversion method that can control the directionality of the output quadrilateral mesh according to a user-specified vector field. Given a triangular mesh and a vector field, the method first scores all possible quadrilaterals that can be formed by pairs of adjacent triangles, according to their shape and directionality. It then converts the pairs into quadrilateral elements in order of the scores to form a quadrilateral mesh. Engineering analyses with finite element methods occasionally require a quadrilateral mesh well aligned along the boundary geometry or the directionality of some physical phenomena, such as in the directions of a streamline, shock boundary, or force propagation vectors. The mesh conversion method can control the mesh directionality according to any desired vector fields, and the method can be used with any existing triangular mesh generators.

Painterly Rendering with Directional Stroke (영역 분할 및 병합을 이용한 방향성을 가지는 스트로크 생성에 관한 연구)

  • Cha, Jeong Seob;Lee, Hyo Keun;Park, Young Sup;Yoon, Kyung Hyun
    • Journal of The Korea Computer Graphics Society
    • /
    • v.8 no.1
    • /
    • pp.21-28
    • /
    • 2002
  • This paper presents a brush stroke direction creation method to distill painterly expressions from picture images. In actual paintings, each brush stroke has the same directionality in one segmented area. but directionality changes in the area of image border edges. This study employed the following methods to implement the directionality of the brush stroke area by: (1) detecting edge in input images, (2) region splitting and merging based on quad-tree division method, and (3) composing a direction map to create brush strokes with the same directionality in the segmented area. The results of the implementation enabled the simulation of the directionality of the stroke area shown in actual paintings.

  • PDF

Asymmetric Directionality of Broadband Ship Radiation Noise at Bow-Stern Aspect (광대역 선박방사소음의 선수-선미 비대칭 방향성)

  • Lee, Keunhwa;Kim, Minkyu;Seong, Woojae
    • The Journal of the Acoustical Society of Korea
    • /
    • v.34 no.5
    • /
    • pp.343-350
    • /
    • 2015
  • In this paper, we perform a study on the directionality of broadband ship radiation noise, mainly resulting from propeller cavitation. By examining a few foreign studies for ship radiation noise and domestic data measured in Korean waters, it is reconfirmed that the asymmetric directionality of the ship radiation noise at bow and stern aspect is observed commonly. In order to explore the reason of this asymmetric directionality, a numerical analysis, based on the acoustic boundary element method, is applied into the geometric form equal to the commercial ship used in the domestic experiment. The numerical result demonstrates that the diffraction of the propeller cavitation noise by ship is a primary cause of the bow-stern asymmetry in the directionality of ship radiation noise.

Influence of ground motion selection methods on seismic directionality effects

  • Cantagallo, Cristina;Camata, Guido;Spacone, Enrico
    • Earthquakes and Structures
    • /
    • v.8 no.1
    • /
    • pp.185-204
    • /
    • 2015
  • This study investigates the impact of the earthquake incident angle on the structural demand and the influence of ground motion selection and scaling methods on seismic directionality effects. The structural demand produced by Non-Linear Time-History Analyses (NLTHA) varies with the seismic input incidence angle. The seismic directionality effects are evaluated by subjecting four three-dimensional reinforced concrete structures to different scaled and un-scaled records oriented along nine incidence angles, whose values range between 0 and 180 degrees, with an increment of 22.5 degrees. The results show that NLTHAs performed applying the ground motion records along the principal axes underestimate the structural demand prediction, especially when plan-irregular structures are analyzed. The ground motion records generate the highest demand when applied along the lowest strength structural direction and a high energy content of the records increases the structural demand corresponding to this direction. The seismic directionality impact on structural demand is particularly important for irregular buildings subjected to un-scaled accelerograms. However, the orientation effects are much lower if spectrum-compatible combinations of scaled records are used. In both cases, irregular structures should be analyzed first with pushover analyses in order to identify the weaker structural directions and then with NLTHAs for different incidence angles.

Application of Directional Wavelet to Ocean Wave Image Analysis (방향 웨이브렛을 적용한 해양파 이미지 분석)

  • Kwon S. H.;Lee H. S.;Park J. S.;Ha M. K.
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.377-380
    • /
    • 2002
  • This paper presents the results of a study investigating methods of interpretation of wave directionality based on wavelet transforms. Two-dimensional discrete wavelet was used for the analysis. The proposed scheme utilizes a single frame of ocean waves to detect their directionality. This fact is striking considering the fact that traditional methods require long time histories of ocean wave elevation measured at various locations. The developed schemes were applied to the data generated from numerical simulations and video images to test the efficiency of the proposed scheme in detecting the directionality of ocean waves.

  • PDF

Development of UML Tool using WPF Framework and Forced-Directionality Graph Algorithm

  • Utama, Ahmad Zulfiana;Jang, Duk-Sung
    • Journal of Korea Multimedia Society
    • /
    • v.22 no.6
    • /
    • pp.706-715
    • /
    • 2019
  • This research implemented grammatical rules for relationship extraction from class diagram candidate. The problem statement is generated by our algorithm to yield class diagram and candidate relationship candidates. The relationships of class diagrams are extracted automatically from the problem statement by using Natural Language Processing (NLP). The extraction used the grammatical rules that obtained from various sources and translated into our algorithm. The performance evaluation of the extraction algorithm used ATM problem statements. The application captures the problem statement and draws automatically the relations of class diagrams using Forced-Directionality Graph algorithm. The performance evaluations show refining methods for class diagram and relationships extraction improve recall score.

Development of GUI Program for Analyzing Directional Spectrum Waves (방향 스펙트럼 파 해석을 위한 GUI 프로그램 개발)

  • 이진호;최재웅;강윤태;하문근
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.41 no.1
    • /
    • pp.1-7
    • /
    • 2004
  • GUI program for analyzing directional spectrum waves is introduced in this paper Basically, MLM (Maximum Likelihood Method) was used for this program which was additionally consisted of performing spectral and time domain analysis for two dimensional irregular waves. Moreover, the directionality of directional spectrum waves generated by single summation and double summation method was investigated based on MLM. The directionality from each summation method has good agreement compared with that of target wave spreading function in the case of single wide directional spectrum waves. In addition to this, the resolution of directionality in double summation method was investigated as introducing coherence function between each wave component

Fragility characteristics of skewed concrete bridges accounting for ground motion directionality

  • Jeon, Jong-Su;Choi, Eunsoo;Noh, Myung-Hyun
    • Structural Engineering and Mechanics
    • /
    • v.63 no.5
    • /
    • pp.647-657
    • /
    • 2017
  • To achieve this goal, two four-span concrete box-girder bridges with typical configurations of California highway bridges are selected as representative bridges: an integral abutment bridge and a seat-type abutment bridge. A detailed numerical model of the representative bridges is created in OpenSees to perform dynamic analyses. To examine the effect of earthquake incidence angle on the fragility of skewed bridges, the representative bridge models are modified with different skew angles. Dynamic analyses for all bridge models are performed for all earthquake incidence angles examined. Simulated results are used to develop demand models and component and system fragility curves for the skewed bridges. The fragility characteristics are compared with regard to earthquake incidence angle. The results suggest that the earthquake incidence angle more significantly affects the seismic demand and fragilities of the integral abutment bridge than the skewed abutment bridge. Finally, a recommendation to account for the randomness due to the ground motion directionality in the fragility assessment is made in the absence of the predetermined earthquake incidence angle.