scholarly journals VOLUMETRIC CELLS: A FRAMEWORK FOR A BIO-INSPIRED GEOMETRIC MODELLING METHOD TO SUPPORT HETEROGENEOUS LATTICE STRUCTURES

2020 ◽  
Vol 1 ◽  
pp. 295-304
Author(s):  
N. Letov ◽  
Y. F. Zhao
Keyword(s):  
Cell Division ◽  
Use Cases ◽  
Geometric Modelling ◽  
Lattice Structures ◽  
Geometrical Modelling ◽  
Modelling Method ◽  
Heterogeneous Lattice ◽  
Modelling Approaches

AbstractCurrent geometrical modelling approaches are unable to handle complex geometrical objects such as heterogeneous lattice structures. In this work, a framework for a novel bio-inspired geometric modelling method is proposed. The method can potentially support geometric modelling of heterogeneous lattice structures. The method utilises discretisation algorithms that are based on cell division processes encountered in nature. The method is verified on two 2D use-cases.

scholarly journals Recent Advances in Material and Geometrical Modelling in Dental Applications

2018 ◽  
Vol 6 (6) ◽  
pp. 1138-1144
Author(s):  
Waleed M. S. Al Qahtani ◽  
Salah A Yousief ◽  
Mohamed I. El-Anwar
Keyword(s):  
Computer Aided Design ◽  
New Technology ◽  
Dental Materials ◽  
Geometric Modelling ◽  
Cad System ◽  
Geometrical Modelling ◽  
Recent Advances ◽  
Wide Range ◽  
Computer Aided ◽  
Dental Applications

This article touched, in brief, the recent advances in dental materials and geometric modelling in dental applications. Most common categories of dental materials as metallic alloys, composites, ceramics and nanomaterials were briefly demonstrated. Nanotechnology improved the quality of dental biomaterials. This new technology improves many existing materials properties, also, to introduce new materials with superior properties that covered a wide range of applications in dentistry. Geometric modelling was discussed as a concept and examples within this article. The geometric modelling with engineering Computer-Aided-Design (CAD) system(s) is highly satisfactory for further analysis or Computer-Aided-Manufacturing (CAM) processes. The geometric modelling extracted from Computed-Tomography (CT) images (or its similar techniques) for the sake of CAM also reached a sufficient level of accuracy, while, obtaining efficient solid modelling without huge efforts on body surfaces, faces, and gaps healing is still doubtable. This article is merely a compilation of knowledge learned from lectures, workshops, books, and journal articles, articles from the internet, dental forum, and scientific groups' discussions.

scholarly journals Additive Manufacturing of Heterogeneous Lattice Structures: An Experimental Exploration

2019 ◽  
Vol 1 (1) ◽  
pp. 669-678
Author(s):  
Francesco Leonardi ◽  
Serena Graziosi ◽  
Riccardo Casati ◽  
Francesco Tamburrino ◽  
Monica Bordegoni
Keyword(s):  
Fused Deposition Modeling ◽  
Bending Test ◽  
Lattice Structures ◽  
Three Point Bending ◽  
Fused Deposition ◽  
Heterogeneous Structures ◽  
Unit Cells ◽  
Deposition Modeling ◽  
Multiple Unit ◽  
Heterogeneous Lattice

Abstract3D printed heterogeneous lattice structures are beam-and-node based structures characterised by a variable geometry. This variability is obtained starting from a periodic structure and modifying the relative density of the unit cells or by combining unit cells having different shapes. While several consolidated design approaches are described to implement the first approach, there are still computational issues to be addressed to combine different cells properly. In this paper, we describe a preliminary experimental study focused on exploring the design issues to be addressed as well as the advantages that this second type of heterogeneous structures could provide. The Three-Point-Bending test was used to compare the behaviour of different types of heterogeneous structures printed using the Fused Deposition Modeling (FDM) technology. Results demonstrated that the possibility of combining multiple unit cells represents a valid strategy for performing a more effective tuning of the material distribution within the design space. However, further studies are necessary to explore the behaviour of these structures and develop guidelines for helping designers in exploiting their potential.

scholarly journals 3D phytomer-based geometric modelling method for plants—the case of maize

AoB Plants ◽  
2021 ◽  
Vol 13 (5) ◽  
Author(s):  
Weiliang Wen ◽  
Yongjian Wang ◽  
Sheng Wu ◽  
Kai Liu ◽  
Shenghao Gu ◽  
...  
Keyword(s):  
In Silico ◽  
3D Models ◽  
Geometric Modelling ◽  
Crop Breeding ◽  
Functional Differences ◽  
Modelling Method ◽  
Maize Plants ◽  
Technical Basis ◽  
Modelling Methods ◽  
Modelling Efficiency

Abstract Geometric plant modelling is crucial in in silico plants. Existing geometric modelling methods have focused on the topological structure and basic organ profiles, simplifying the morphological features. However, the models cannot effectively differentiate cultivars, limiting FSPM application in crop breeding and management. This study proposes a 3D phytomer-based geometric modelling method with maize (Zea Mays) as the representative plant. Specifically, conversion methods between skeleton and mesh models of 3D phytomer are specified. This study describes the geometric modelling of maize shoots and populations by assembling 3D phytomers. Results show that the method can quickly and efficiently construct 3D models of maize plants and populations, with the ability to show morphological, structural and functional differences among four representative cultivars. The method takes into account both the geometric modelling efficiency and 3D detail features to achieve automatic operation of geometric modelling through the standardized description of 3D phytomers. Therefore, this study provides a theoretical and technical basis for the research and application of in silico plants.

Challenges and Opportunities in Geometric Modelling of Complex Bio-Inspired 3D Objects Designed for Additive Manufacturing

2021 ◽  
pp. 1-27
Author(s):  
Nikita Letov ◽  
Pavan Tejaswi Velivela ◽  
Siyuan Sun ◽  
Yaoyao Fiona Zhao
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Geometric Modelling ◽  
Survey Paper ◽  
Engineering Software ◽  
Modelling Method ◽  
Geometric Objects ◽  
Computer Aided ◽  
Challenges And Opportunities

Abstract Ever since its introduction over five decades ago, geometric solid modelling has been crucial for engineering design purposes and is used in engineering software packages such as computer-aided design (CAD), computer-aided manufacturing (CAM), computer-aided engineering (CAE), etc. Solid models produced by CAD software have been used to transfer geometric information from designers to manufacturers. Since the emergence of additive manufacturing (AM), a CAD file can also be directly uploaded to a three-dimensional (3D) printer and used for production. AM techniques allow manufacturing of complex geometric objects such as bio-inspired structures and lattice structures. These structures are shapes inspired by nature and periodical geometric shapes consisting of struts interconnecting in nodes. Both structures have unique properties such as significantly reduced weight. However, geometric modelling of such structures has significant challenges due to the inability of current techniques to handle their geometric complexity. This calls for a novel modelling method that would allow engineers to design complex geometric objects. This survey paper reviews geometric modelling methods of complex structures to support bio-inspired design created for AM which includes discussing reasoning behind bio-inspired design, limitations of current modelling approaches applied to bio-inspired structures, challenges encountered with geometric modelling and opportunities that these challenges reveal. Based on the review, a need for a novel geometric modelling method for bio-inspired geometries produced by AM is identified. A framework for such bio-inspired geometric modelling method is proposed as a part of this work.

Miura-Base Rigid Origami: Parameterizations of First-Level Derivative and Piecewise Geometries

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Joseph M. Gattas ◽  
Weina Wu ◽  
Zhong You
Keyword(s):  
Geometric Modelling ◽  
Matlab Toolbox ◽  
Plate Structures ◽  
Widespread Application ◽  
The Relationship ◽  
Modelling Approaches

Miura and Miura-derivative rigid origami patterns are increasingly used for engineering and architectural applications. However, geometric modelling approaches used in existing studies are generally haphazard, with pattern identifications and parameterizations varying widely. Consequently, relationships between Miura-derivative patterns are poorly understood, and widespread application of rigid patterns to the design of folded plate structures is hindered. This paper explores the relationship between the Miura pattern, selected because it is a commonly used rigid origami pattern, and first-level derivative patterns, generated by altering a single characteristic of the Miura pattern. Five alterable characteristics are identified in this paper: crease orientation, crease alignment, developability, flat-foldability, and rectilinearity. A consistent parameterization is presented for five derivative patterns created by modifying each characteristic, with physical prototypes constructed for geometry validation. It is also shown how the consistent parameterization allows first-level derivative geometries to be combined into complex piecewise geometries. All parameterizations presented in this paper have been compiled into a matlab Toolbox freely available for research purposes.

scholarly journals 3D CITYLUR: MODELLING 3D CITY LAND-USE REGULATIONS TO SUPPORT ISSUING A PLANNING PERMIT

2021 ◽  
Vol VIII-4/W2-2021 ◽  
pp. 113-120
Author(s):  
S. Emamgholian ◽  
J. Pouliot ◽  
D. Shojaei
Keyword(s):  
Land Use ◽  
Open Space ◽  
Physical World ◽  
Boundary Representation ◽  
Geometric Modelling ◽  
Information Need ◽  
Land Use Regulations ◽  
Building Height ◽  
Gis Environment ◽  
Modelling Approaches

Abstract. The applications and understanding of Land-use Regulations (LuR) are more communicable when they are linked to the digital representation of the physical world. In order to support issuing a planning permit and move towards the establishment of automated planning permit checks, this paper investigates how LuRs related to a planning permit process can be modelled in 3D called 3D CityLuR. 3D CityLuR serves as a 3D model for representing LuRs’ legal extents on a city scale. It is formed based on multiple geometric modelling approaches representing LuRs, which can provide a better cognitive understanding of LuRs and subsequently facilitate LuR automatic checks. To this purpose, according to LuRs’ descriptions and characteristics explained in related planning documents, key parameters representing LuRs’ extent are identified (e.g. maximum distance in overlooking or maximum allowed height in building height regulations). Accordingly, to automatically model each LuR, a geometric modelling approach (e.g. Boundary Representation (B-Rep), CSG, and extrusion) that best fits with the identified key parameters is proposed. In addition, to combine 3D CityLuR with an integrated BIM-GIS environment, the level of information need in terms of geometries and semantics is specified. Finally, the paper results in a showcase for five LuRs including building height, energy efficiency protection, overshadowing open space, overlooking, and noise impacts regulations. The showcase is a proof of concept for determining how these LuRs can be modelled in 3D and combined with 3D city models based on the selected geometric modelling approaches, identified parameters, and level of information need.

A Survey of Modeling and Optimization Methods for Multi-Scale Heterogeneous Lattice Structures

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Yuan Liu ◽  
Guolei Zheng ◽  
Nikita Letov ◽  
Yaoyao Fiona Zhao
Keyword(s):  
Geometric Modeling ◽  
Optimization Design ◽  
Optimization Methods ◽  
Lattice Structures ◽  
Modeling And Optimization ◽  
Multi Scale ◽  
Advantages And Disadvantages ◽  
Material Optimization ◽  
The Relationship ◽  
Heterogeneous Lattice

Abstract This paper aims to provide a comprehensive review of the state-of-the-art modeling and optimization methods for multi-scale heterogeneous lattice structures (MSHLS) to further facilitate the more design freedom. In this survey, a design process including optimization and modeling for MSHLS is proposed. Material composition and multi-scale geometric modeling methods for representation of material and geometry information are separately discussed. Moreover, the optimization methods including multi-scale and multi-material optimization design methods, as well as the simulation methods suitable for MSHLS are, respectively, reviewed. Finally, the relationship, advantages, and disadvantages of MSHLS modeling and optimization methods are summarized with discussion and comparison, which provides a guidance to further take advantage of MSHLS to improve the performance and multifunctional purpose of production for software developers and researchers concerning the design approaches and strategies currently available.

The Ultrastructure of the Nuclear Events of Binary Fission in Paramecium bursaria and the Effects of Colchicine on Cell Division

1974 ◽  
Vol 32 ◽  
pp. 276-277
Author(s):  
L. M. Lewis
Keyword(s):  
Cell Division ◽  
Nuclear Envelope ◽  
Condensed Chromatin ◽  
Binary Fission ◽  
Paramecium Bursaria ◽  
Nuclear Events ◽  
Division Axis

The effects of colchicine on extranuclear microtubules associated with the macronucleus of Paramecium bursaria were studied to determine the possible role that these microtubules play in controlling the shape of the macronucleus. In the course of this study, the ultrastructure of the nuclear events of binary fission in control cells was also studied.During interphase in control cells, the micronucleus contains randomly distributed clumps of condensed chromatin and microtubular fragments. Throughout mitosis the nuclear envelope remains intact. During micronuclear prophase, cup-shaped microfilamentous structures appear that are filled with condensing chromatin. Microtubules are also present and are parallel to the division axis.

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