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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Variabilita křídelní žilnatiny vážek (Insecta: Odonata) - geometricko-morfometrická studie / Variation in dragonfly wing venation with application of geometric morphometrics (Insecta: Odonata)

Přibylová, Petra January 2015 (has links)
The pattern of wing venation in dragonflies (Odonata) bears a set of characters commonly used in systematics. The aim of this thesis is to identify the wing venation variability of dragonflies by various methods of geometric morphometric. The wing venation variability was examined on the level of suborder, family, species and also in respect to dimorphism through the principal component analysis (PCA), redundancy analysis (RDA) and centroid size. Data set consisting of images of 46 dragonfly species, belonging to 43 genera and 24 families was obtained from institutional entomological collections. The research carried out that Zygoptera have a large variety of wing contours. The wing venation variability of Epiprocta is shown primarily in the costa and node area. Between sexes there is no noticeable difference in shape or structure of the wing. The ratio between wing length and width and the pterostigma shape is dependent on dragonfly body size. Key words: Odonatoptera, Odonata, Epiprocta, Zygoptera, wing venation, variability, geometric morphometrics
2

Morfologie a evoluce vybraných skupin Palaeodictyopterida (Insecta: Palaeoptera) / Morphology and evolution of selected groups of Palaeodictyopterida (Insecta: Palaeoptera)

Pecharová, Martina January 2017 (has links)
Palaeodictyopterida is remarkable insect superorder, which formed a significant part of the diversity of upper Palaeozoic insects, but disappeared by the end of the Permian. The main synapomorphy of the superorder is the piercing-sucking mouthparts in the form of a rostrum consisting of five styles. This rostrum was probably used to pierce on plant tissue and for the juice sucking. The same type of mouthparts shared by adults was present also in larvae of Palaeodictyopterida. The external copulatory organs of the superorder members was also showed some morphological interests. The male genitalia consist of a pair of gonostyli and two penial lobes, similarly to the genitalia of recent Ephemeroptera. The female genitalia of Palaeodictyopterida are developed in a form of the ovipositor that can be compared with the endophytic ovipositor of some recent Odonata. This morphological features support placement of Palaeodictyopterida as sister group of Odonatoptera + Panephemeroptera. The main aim of the work was to describe new representatives of the order Megasecoptera, the second largest group of Palaeodictyopterida. Wing venation of Megasecoptera exhibits a reduction of the longitudinal and transverse veins in comparison with the order Palaeodictyoptera. Other body structures were examined mainly in the...
3

Discovering the Complex Aerodynamics of Flapping Flight with Bio-kinematics Using Boltzmann and Eulerian Methods

Feaster, Jeffrey Oden 31 August 2017 (has links)
The cross-sectional geometry of an insect wing has historically been simplified to a rectangular, elliptic, or having a streamlined airfoil shape. Up until this point, no analysis has utilized a morphologically accurate insect wing. As such, there remains significant questions as to whether or not there are aerodynamic benefits to the wing vein structure accompanying the already known structural improvements. The present study uses a bumblebee specimen (Bombus pensylvanicus) acquired by the author, scanned using a skyscan microCT scanner, and post-processed for computational analysis. The resulting geometry captures the naturally occurring vein structures present in the bee wing and is used to better understand aerodynamic effects of biological corrugation. The aerodynamics associated with a morphologically accurate bee wing geometry are explored in two and three dimensions for the first time. Multiple methodologies are validated with experimental results presented in the literature to capture the fluid dynamics in two dimensions including the Lattice-Boltzmann method and unstructured dynamic remeshing using a Navier-Stokes approach. The effects of wing cross-section are compared first with common geometries used in the literature in two dimensions and then between cross-sections extracted at different locations along the wing span. A three-dimensional methodology is validated and used to compare the true bee wing with one using a rectangular cross-section in symmetric hovering. The influence of spanwise cross-section is revisited in three dimensions and compared to the results found in two-dimensions for the same kinematics in forward flight. The final focus of the dissertation is the first simulation of a morphologically accurate wing using kinematics described in the literature. / PHD / Insect flight has been an area of fascination and interest, going through phases of observation, experimentation and most recently, computational analysis. The modern paradigm for computational fluid dynamics analysis of insect flight uses an accurate planform of the wing with the cross-section simplified to an airfoil, ellipse, or rectangular plate. In reality, insect wings exhibit a vein structure which yields a complex geometry. The vein system along the wing has already been proven to have structural benefits, arresting crack propagation and adding to the overall stiffness of the wing, yet the aerodynamic properties have remained notably unexplored. The present work uses a scanned three-dimensional representation of a bee wing to explore the possible influences wing cross-section has on aerodynamic performance, and establishes a validated computational methodology to do so in two and three dimensions. The presented work begins by comparing and evaluating the forces and flow field around two-dimensional representations of the true wing with cross-sections common to the literature. Based on the results from the two-dimensional cross-sectional study, there were distinct differences observed between geometries which motivated further study into geometric variation with spanwise location. The comparison across spanwise location for the true bee wing determined that there were numerous coincident structures present along the wing, lending credence to the possibility that the vein structure is also of aerodynamic benefit. The analysis then moved to three dimensions, re-investigating cross-sectional effects in hovering and then evaluating spanwise variation in two and three dimensions. The dissertation concludes with the first analysis of a true bee wing using kinematics described in the literature.
4

Morfologie a taxonomie nově objevených zástupců skupiny Megasecoptera ze svrchního karbonu severní Číny (Insecta: Palaeodictyopteroida) / Megasecoptera: morphology and taxonomy of newly discovered specimens from Upper Carboniferous of northern China (Insecta: Palaeodictyopteroida)

Pecharová, Martina January 2013 (has links)
The extinct insect group of Palaeodictyopteroida (Insecta: Palaeoptera) comprised mainly phytophagous species and occurred from Upper Carboniferous to Upper Permian. Megasecoptera is one of several orders of belonging to this group. Although, the order Megasecoptera comprised over 20 described families, morphology of some body structures are insufficiently studied. The present thesis deals with evaluation of new material comprising the extensive set of 76 fossil insect specimens from the Upper Carboniferous (Bashkirian) of northern China. The fossils having excellent state of preservation of the wings and other body structures provide new insights concerning the external morphology of Megasecoptera. All studied specimens were attributed based on wing venation pattern into two known megasecopteran genera within families Brodiopteridae and Sphecopteridae. The aim of the present thesis is examine the morphology and variability of wing venation of two newly proposed species Brodioptera sp. n. and Cyclocelis sp. n. from site in northern China. In addition the following methods of geometric morphometrics based on landmarks were used for comparison of venational characters: a comparison of centroid size, procrustes analysis, principal component analysis and thin plate spline. Variability of wing venation...
5

Morfologie křídelní nervatury larválních stádií Palaeodictyoptera ze svrchního karbonu Polska / Palaeodictyoptera: morphology of immature wings from the Upper Carboniferous of Poland

Tippeltová, Zuzana January 2013 (has links)
Insect wings are very specific and unique structures in animal kingdom. Wing morphology is a result of long-standing complicated evolutionary process and until recently the way how the wings have evolved is not completely clarified. The flight ability is one of the most important event in insect history because it allows them to exploit new habitats, escape from predators or find the sexual partner. Here we present the newly discovered material consisting of Palaeodictyoptera immature wings from the Upper Carboniferous (Westphalian A) of Poland. This order became extinct in the end of Permian, however during the Late Paleozoic was remarkably diversified. Until recently, number of adult palaeodictyopterans have been described, however the immature stages are relatively unknown due to lack of suitable fossils. Immature wings present in this thesis have undoubtedly palaeodictyopterous affinities with atribution within superfamilies Breyeroidea and Homoiopteroidea. However, their familial assignment into Breyeriidae (morphotype A) and Homiopteridae (morphotype B) based on fore wing venation characters is not definite because of wing venation limits in early ontogenetic stages. The aim of the present work is a complex description of 14 new palaeodictyopteriids immature wings, and to point out certain important...

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