• Title/Summary/Keyword: Curved boundaries

Search Result 42, Processing Time 0.021 seconds

Groundwater Flow Model for the Pollutant Transport in Subsurface Porous Media Theory and Modeling (지하다공질(地下多孔質) 매체(媒體)속에서의 오염물질이동(汚染物質移動) 해석(解析)을 위한 지하수(地下水)흐름 모형(模型))

  • Cho, Won Cheal
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.9 no.3
    • /
    • pp.97-106
    • /
    • 1989
  • This paper is on the modeling of two-dimensional groundwater flow, which is the first step of the development of Dynamic System Model for groundwater flow and pollutant transport in subsurface porous media. The particular features of the model are its versatility and flexibility to deal with as many real-world problems as possible. Points as well as distributed sources/sinks are included to represent recharges/pumping and rainfall infiltrations. All sources/sinks can be transient or steady state. Prescribed hydraulic head on the Dirichlet boundaries and fluxes on Neumann or Cauchy boundaries can be time-dependent or constant. Sources/sinks strength over each element and node, hydraulic head at each Dirichlet boundary node and flux at each boundary segment can vary independently of each other. Either completely confined or completely unconfined aquifers, or partially confined and partially unconfined aquifers can be dealt with effectively. Discretization of a compound region with very irregular curved boundaries is made easy by including both quadrilateral and triangular elements in the formulation. Large-field problems can be solved efficiently by including a pointwise iterative solution strategy as an optional alternative to the direct elimination solution methed for the matrix equation approximating the partial differential equation of groundwater flow. The model also includes transient flow through confining leaky aquifers lying above and/or below the aquifer of interest. The model is verified against three simple cases to which analytical solutions are available. The groundwater flow model shall be combined with the model of pollutant transport in subsurface porous media. Then the combined model, with the applications of the Eigenvalue technique and the Dynamic system theory, shall be improved to the Dynamic System Model which can simulate the real groundwater flow and the pollutant transport accurately and effectively for the analyses and predictions.

  • PDF

Techniques of Automatic Finite Element Mesh Generation on Surface Primitives (원시곡면 위의 유한요소망 자동생성 기법)

  • 이재영
    • Korean Journal of Computational Design and Engineering
    • /
    • v.1 no.3
    • /
    • pp.189-202
    • /
    • 1996
  • Complex geometric shapes can be defined simply and efficiently by combining and operating various surface primitives. These primitives and their intersection curves are used in finite element mesh generation to form an easy and intuitive procedure for finite element modelling of curved surfaces. This paper proposes techniques of automatic mesh generation on surface primitives with arbitrarily shaped boundaries and control curves, which may be created by surface to surface intersection. A method of automatic mesh generation on plane, which was previously developed by the author, has been modified for application to the surface mesh generation. Owing to the mesh generation-wise differences between planes and surfaces, the surfaces should be transformed into conceptual plane so that the modified plane mesh generation method can be applied. Surface development, mapping and mesh reconstruction are the key techniques suggested in this paper. The selection of the technique to apply can be determined automatically on the basis of the developability, existence of singularity and other characteristics of the surfaces on which the mesh is to be generated. The suggested techniques were implemented into parts of mesh generation functions of the finite element software, MacTran. Their validity and practicality were manifested by the actual use of this software.

  • PDF

NUMERICAL STUDY ON THE CHARACTERISTICS OF NON-NEWTONIAN FLUID FLOW OVER OBSTACLE (장애물 주위의 비뉴턴 유체의 유동특성에 관한 수치적 연구)

  • Kim, Hyung Min
    • Journal of computational fluids engineering
    • /
    • v.19 no.4
    • /
    • pp.61-67
    • /
    • 2014
  • Since the most of the existing non-Newtonian models are not adequate to apply to the lattmce Boltzmann method, it is a challenging task from both the theoretical and the numerical points of view. In this research the hydro-kinetic model was modified and applied to the 3-D moving sphere in the circular channel flow and the characteristics of the shear thinning effect by the HK-model was evaluated and the condition of ${\Gamma}$ in the model was suggested for the stable simulation to generate non-trivial prediction in three dimension strong shear flows. On the wall boundaries of circular channel the curved wall surface treatment with constant velocity condition was applied and the bounceback condition was applied on the sphere wall to simulate the relative motion of the sphere. The condition is adequate at the less blockage than 0.7 but It may need to apply a multi-scale concept of grid refinement at the narrow flow region. to obtain the stable numerical results.

Free Vibration Analysis of Arbitrarily Shaped Plates with Free Edges Using Non-dimensional Dynamic Influence Functions: the case that straight and curved boundaries are mixed (무차원 동영향 함수를 이용한 자유단 경계를 가진 임의 형상 평판의 진동해석 : 직선 및 곡선 경계가 혼합된 경우)

  • Choi, Jang-Hoon;Kang, Sang-Wook
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2005.06a
    • /
    • pp.534-537
    • /
    • 2005
  • Free Vibration Analysis using Non-dimensional Dynamic Influence Function (NDIF) is extended to arbitrarily shaped plates including polygonal plates. Since the corners of polygonal plates have indefinite normal directions and additional boundary conditions related to a twisting moment at a corner along with moment and shear force zero conditions, it is not easy to apply the NDIF method to polygonal plates wi th the free boundary condition. Moreover, owing to the fact that the local polar coordinate system, which has been introduced for free plates with smoothly varying edges, cannot be employed for the straight edges of the polygonal plates, a new coordinate system is required for the polygonal plates. These problems are solved by developing the new method of modifying a corner into a circular arc and setting the normal direction at the corner to an average value of normal direct ions of two edges adjacent to the corner. Some case studies for plates with various shapes show that the proposed method gives credible natural frequencies and mode shapes for various polygons that agree well with those by an exact method or FEM (ANSYS).

  • PDF

A Reference Trajectory Generation Method with Piecewise Constant Acceleration Condition for the Curved Flight of a Drone (드론의 곡선 비행을 위한 구간별 등가속 조건의 기준 궤적 생성 방법)

  • Jang, Jong Tai;Gong, Hyeon Cheol;Lyou, Joon
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.22 no.3
    • /
    • pp.233-240
    • /
    • 2016
  • This paper describes a three-dimensional reference trajectory generation method for giving commands to an unmanned air vehicle (UAV). The trajectory is a set of consecutive curves with constant acceleration during each interval and passing through via-points at specified times or speeds. The functional inputs are three-dimensional positions and times (or speeds) at via-points, and velocities at both boundaries. Its output is the time series of position values satisfying the piecewise constant acceleration condition. To be specific, the shape of the trajectory, known as the path, is first represented by splines using third degree polynomials. A numeric algorithm is then suggested, which can overcome the demerits of cubic spline method and promptly generate a piecewise constant acceleration trajectory from the given path. To show the effectiveness of the present scheme, trajectory generation cases were treated, and their speed calculation errors were evaluated.

The 2021 Australian/New Zealand Standard, AS/NZS 1170.2:2021

  • John D. Holmes;Richard G.J. Flay;John D. Ginger;Matthew Mason;Antonios Rofail;Graeme S. Wood
    • Wind and Structures
    • /
    • v.37 no.2
    • /
    • pp.95-104
    • /
    • 2023
  • The latest revision of AS/NZS 1170.2 incorporates some new research and knowledge on strong winds, climate change, and shape factors for new structures of interest such as solar panels. Unlike most other jurisdictions, Australia and New Zealand covers a vast area of land, a latitude range from 11° to 47°S climatic zones from tropical to cold temperate, and virtually every type of extreme wind event. The latter includes gales from synoptic-scale depressions, severe convectively-driven downdrafts from thunderstorms, tropical cyclones, downslope winds, and tornadoes. All except tornadoes are now covered within AS/NZS 1170.2. The paper describes the main features of the 2021 edition with emphasis on the new content, including the changes in the regional boundaries, regional wind speeds, terrain-height, topographic and direction multipliers. A new 'climate change multiplier' has been included, and the gust and turbulence profiles for over-water winds have been revised. Amongst the changes to the provisions for shape factors, values are provided for ground-mounted solar panels, and new data are provided for curved roofs. New methods have been given for dynamic response factors for poles and masts, and advice given for acceleration calculations for high-rise buildings and other dynamically wind-sensitive structures.

Chaotic phenomena in the organic solar cell under the impact of small particles

  • Jing, Pan;Zhe, Jia;Guanghua, Zhang
    • Steel and Composite Structures
    • /
    • v.46 no.1
    • /
    • pp.15-31
    • /
    • 2023
  • Organic solar cells utilized natural polymers to convert solar energy to electricity. The demands for green energy production and less disposal of toxic materials make them one of the interesting candidates for replacing conventional solar cells. However, the different aspects of their properties including mechanical strength and stability are not well recognized. Therefore, in the present study, we aim to explore the chaotic responses of these organic solar cells. In doing so, a specific type of organic solar cell constructed from layers of material with different thicknesses is considered to obtain vibrational and chaotic responses under different boundaries and initial conditions. A square plate structure is examined with first-order shear deformation theory to acquire the displacement field in the laminated structure. The bounding between different layers is considered to be perfect with no sliding and separation. On the other hand, nonlocal elasticity theory is engaged in incorporating the structural effects of the organic material into calculations. Hamilton's principle is adopted to obtain governing equations with regard to boundary conditions and mechanical loadings. The extracted equations of motion were solved using the perturbation method and differential quadrature approach. The results demonstrated the significant effect of relative glass layer thickness on the chaotic behavior of the structure with higher relative thickness leading to less chaotic responses. Moreover, a comprehensive parameter study is presented to examine the effects of nonlocality and relative thicknesses on the natural frequency of square organic solar cell structure.

Geometric optimization of the D-shape gallery openings on high arch dams against strong ground motions

  • Murat Cavuslu;Tuna Ulger;Berna Aksoy
    • Structural Engineering and Mechanics
    • /
    • v.92 no.5
    • /
    • pp.433-452
    • /
    • 2024
  • Arch dams are often preferred in narrow, high valleys due to their distinctively high and curved geometries, making them particularly effective for water retention. Consequently, assessing the seismic performance of these critical structures is essential. The presence of gallery openings within arch dams further heightens research interest, especially in regions of high seismic activity. This study presents a detailed three-dimensional (3D) numerical failure analysis of the Ermenek Dam, one of Turkey's largest arch dams. Using the finite-difference method, a 3D model is constructed, incorporating four distinct D-shaped gallery openings within the dam body. These openings are integrated into the model using specialized FLAC3D fish functions. To enhance simulation accuracy, the foundation is proportionally extended along the dam's base and sides. The Burgers creep material model is applied to assess both creep behavior and seismic response within the concrete body and foundation. Non-reflecting boundary conditions are imposed on the model boundaries to create realistic constraints. Numerical analyses are conducted on various gallery dimensions, evaluating 28 distinct geometries under ten different strong ground motions. The seismic analysis results indicate that damage may occur within the dam body when gallery height exceeds twice its width. Therefore, careful consideration of the geometrical dimensions of gallery openings is highly recommended during the modeling and analysis of arch dams.

Data interoperability between authoring software and BIM system focused on the office building in conceptual design phase (설계 초기 단계 형상정보 연동 데이터 호환체계 개발 - 오피스 매스를 중심으로)

  • Park, Jung-Dae
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.21 no.11
    • /
    • pp.494-500
    • /
    • 2020
  • Owing to the complexity of shapes and elements, some difficulties are found in the modeling and sharing phases in a project at the earlier design stages. This paper extends the boundaries by suggesting the data interoperability between 3D modeling software, McNeel Rhino 3D and BIM system, and Autodesk® Revit® Architecture. The main research methodology is to link the architectural form data in the NURBS supporting the 3DM format, especially for integrating surface properties into the mass family template of Revit. This algorithm-driven interoperability approach using visual programming, such as Dynamo in conjunction with Autodesk®, can be applicable in a theoretical part and also a practical use-case. This paper summarizes these results as sequence guidelines and project template recommendations suggesting an efficient design process to interoperate geometric data with the BIM system to manipulate and control the regular and curved form of office buildings.

Arabic Words Extraction and Character Recognition from Picturesque Image Macros with Enhanced VGG-16 based Model Functionality Using Neural Networks

  • Ayed Ahmad Hamdan Al-Radaideh;Mohd Shafry bin Mohd Rahim;Wad Ghaban;Majdi Bsoul;Shahid Kamal;Naveed Abbas
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.17 no.7
    • /
    • pp.1807-1822
    • /
    • 2023
  • Innovation and rapid increased functionality in user friendly smartphones has encouraged shutterbugs to have picturesque image macros while in work environment or during travel. Formal signboards are placed with marketing objectives and are enriched with text for attracting people. Extracting and recognition of the text from natural images is an emerging research issue and needs consideration. When compared to conventional optical character recognition (OCR), the complex background, implicit noise, lighting, and orientation of these scenic text photos make this problem more difficult. Arabic language text scene extraction and recognition adds a number of complications and difficulties. The method described in this paper uses a two-phase methodology to extract Arabic text and word boundaries awareness from scenic images with varying text orientations. The first stage uses a convolution autoencoder, and the second uses Arabic Character Segmentation (ACS), which is followed by traditional two-layer neural networks for recognition. This study presents the way that how can an Arabic training and synthetic dataset be created for exemplify the superimposed text in different scene images. For this purpose a dataset of size 10K of cropped images has been created in the detection phase wherein Arabic text was found and 127k Arabic character dataset for the recognition phase. The phase-1 labels were generated from an Arabic corpus of quotes and sentences, which consists of 15kquotes and sentences. This study ensures that Arabic Word Awareness Region Detection (AWARD) approach with high flexibility in identifying complex Arabic text scene images, such as texts that are arbitrarily oriented, curved, or deformed, is used to detect these texts. Our research after experimentations shows that the system has a 91.8% word segmentation accuracy and a 94.2% character recognition accuracy. We believe in the future that the researchers will excel in the field of image processing while treating text images to improve or reduce noise by processing scene images in any language by enhancing the functionality of VGG-16 based model using Neural Networks.