266 research outputs found

    High-performance geometric vascular modelling

    Get PDF
    Image-based high-performance geometric vascular modelling and reconstruction is an essential component of computer-assisted surgery on the diagnosis, analysis and treatment of cardiovascular diseases. However, it is an extremely challenging task to efficiently reconstruct the accurate geometric structures of blood vessels out of medical images. For one thing, the shape of an individual section of a blood vessel is highly irregular because of the squeeze of other tissues and the deformation caused by vascular diseases. For another, a vascular system is a very complicated network of blood vessels with different types of branching structures. Although some existing vascular modelling techniques can reconstruct the geometric structure of a vascular system, they are either time-consuming or lacking sufficient accuracy. What is more, these techniques rarely consider the interior tissue of the vascular wall, which consists of complicated layered structures. As a result, it is necessary to develop a better vascular geometric modelling technique, which is not only of high performance and high accuracy in the reconstruction of vascular surfaces, but can also be used to model the interior tissue structures of the vascular walls.This research aims to develop a state-of-the-art patient-specific medical image-based geometric vascular modelling technique to solve the above problems. The main contributions of this research are:- Developed and proposed the Skeleton Marching technique to reconstruct the geometric structures of blood vessels with high performance and high accuracy. With the proposed technique, the highly complicated vascular reconstruction task is reduced to a set of simple localised geometric reconstruction tasks, which can be carried out in a parallel manner. These locally reconstructed vascular geometric segments are then combined together using shape-preserving blending operations to faithfully represent the geometric shape of the whole vascular system.- Developed and proposed the Thin Implicit Patch method to realistically model the interior geometric structures of the vascular tissues. This method allows the multi-layer interior tissue structures to be embedded inside the vascular wall to illustrate the geometric details of the blood vessel in real world

    Biology And Phylogeny Of The Cassidinae Gyllenhal Sensu Lato (Tortoise And Leaf-Mining Beetles) (Coleoptera: Chrysomelidae)

    Get PDF
    A parsimony analysis was undertaken to test subfamily and tribal group concepts of Cassidinae (ca. 2000 genera, ca. 6000 species). An integrated account of their biology was synthesized from the primary literature. A detailed morphological study of adults, using Hemisphaerota palmarum Boheman as a model, formed the basis for evaluating characters previously utilized and for defining novel characters. The data matrix comprised 210 characters (from adults and immature stages, ecology and behavior), 6 outgroups, and 98 ingroup exemplar species (representing 94 genera and 39 of the 43 recognized cassidine tribes). Results support the monophyly of Cassidinae and place it as sister to Galerucinae. The classical Hispinae s.str. is paraphyletic whereas the classical Cassidinae s.str. is monophyletic if some Imatidiine genera are included. Four tribes—Aproidini, Delocraniini, Hemisphaerotini, and Notosacanthini—are well supported by many autapomorphies. Multiple genera were sampled to test the monophyly of 14 cassidine tribes. Seven were recovered as monophyletic: Anisoderini, Cassidini, Dorynotini, Eugenysini, Hispini, Omocerini, and Spilophorini. Relationships and character support of all cassidine tribes are discussed and compared with phylogenies proposed by Borowiec (1995) and Hsiao and Windsor (1999). The biological account and these phylogenetic results provide an opportunity for identifying some general trends and major innovations in the evolutionary history of Cassidinae. The alteration of the adult head from prognathy to hypognathy and the compaction of the body, legs, and various elytral-locking mechanisms are recurrent themes in adult morphology. Maternal care may have arisen once or twice. Seven trophic guilds are defined here for Cassidine larvae. They arise from two large radiations of leaf-mining and exophagous-feeding, a minor radiation in cryptic rolled-leaf feeding, and small generic and sub-generic specializations in stem mining, leaf scraping, petalophagy, and leaf-shelter chewers. Fecal shield construction and retention appear to be correlated with innovations in life history and in larval and pupal morphology, and they may have played an important role in cassidine diversification

    Development of well-behaved nonlinear structures

    Get PDF

    Mechanical Self-Assembly of a Strain-Engineered Flexible Layer: Wrinkling, Rolling, and Twisting

    Get PDF
    Self-shaping of curved structures, especially those involving flexible thin layers, has attracted increasing attention because of their broad potential applications in e.g. nanoelectromechanical/micro-electromechanical systems (NEMS/MEMS), sensors, artificial skins, stretchable electronics, robotics, and drug delivery. Here, we provide an overview of recent experimental, theoretical, and computational studies on the mechanical self-assembly of strain-engineered thin layers, with an emphasis on systems in which the competition between bending and stretchingenergy gives rise to a variety ofdeformations,such as wrinkling, rolling, and twisting. We address the principle of mechanical instabilities, which is often manifested in wrinkling or multistability of strain-engineered thin layers. The principles of shape selection and transition in helical ribbons are also systematically examined. We hope that a more comprehensive understanding of the mechanical principles underlying these rich phenomena can foster the development of new techniques for manufacturing functional three- dimensional structures on demand for a broad spectrum of engineering applications.Comment: 91 pages, 35 figures, review articl

    Annual Report of the Board of Regents of the Smithsonian Institution, showing the operations, expenditures, and condition of the Institution to July, 1897.

    Get PDF
    Annual Report of the Smithsonian Institution. 14 Apr. HD 575 (pts. 1-3), 55-2, v78-79 (pts. 1 and 2), 1228p. [3706-3708] Research related to the American Indian

    საქართველოს ამპელოგრაფია

    Get PDF
    The editing commission of the book decided to re-publish “Georgian Ampelography” as it was created the first time by N. Ketskhoveli, M. Ramishvili and D. Tabidze. However, the decision was made to complement the definitions of terms and toponyms with brief description and illustration reflecting the development of Georgian viticulture and enology from the 1960s to present day.The new edition of Georgian Ampelograpy is translated in english

    KINE[SIS]TEM'17 From Nature to Architectural Matter

    Get PDF
    Kine[SiS]tem – From Kinesis + System. Kinesis is a non-linear movement or activity of an organism in response to a stimulus. A system is a set of interacting and interdependent agents forming a complex whole, delineated by its spatial and temporal boundaries, influenced by its environment. How can architectural systems moderate the external environment to enhance comfort conditions in a simple, sustainable and smart way? This is the starting question for the Kine[SiS]tem’17 – From Nature to Architectural Matter International Conference. For decades, architectural design was developed despite (and not with) the climate, based on mechanical heating and cooling. Today, the argument for net zero energy buildings needs very effective strategies to reduce energy requirements. The challenge ahead requires design processes that are built upon consolidated knowledge, make use of advanced technologies and are inspired by nature. These design processes should lead to responsive smart systems that deliver the best performance in each specific design scenario. To control solar radiation is one key factor in low-energy thermal comfort. Computational-controlled sensor-based kinetic surfaces are one of the possible answers to control solar energy in an effective way, within the scope of contradictory objectives throughout the year.FC

    Fourth Annual Report of the Bureau of Ethnology to the Secretary of the Smithsonian Institution 1882-'83.

    Get PDF
    48-2Annual Report of the Bureau of Ethno logy. [2327] Research related to the American Indian; fourth annual report.1885-

    Fourth Annual Report of the Bureau of Ethnology to the Secretary of the Smithsonian Institution 1882-\u2783.

    Get PDF
    Annual Report of the Bureau of Ethnology. [2327] Research related to the American Indian; fourth annual report
    corecore