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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.
21

Rekultivace území zasažených těžbou a jejich možné začlenění do projektu KPÚ / Reclamation of land affected by mining and their possible integration into project of comprehensive land adjustment

MATOUŠKOVÁ, Jana January 2015 (has links)
The aim of this thesis is detailed description of solved reclamation in the selected location Cep II after gravel extraction. The part of thesis solves property settlements on the parcels concerned. The literary review outlines generally issue of mining and its impact on the landscape and ways of deal with these negative impacts. Besides the classical methods of reclamation (agricultural, forestry and hydrological reclamation) is described a method of using spontaneous restoration. There is also particularised the possibility of incorporating suitably reclaimed parcels into territorial system of ecological stability in terms of land adjustment.
22

Land Privatization, Tenure Security, and Food Security in Rural Burkina Faso

Gardiner, Elizabeth N. January 2020 (has links)
No description available.
23

Problematika rozvodu manželství a jeho důsledků / The issues of marriage divorce and its consequences

Němeček, Eduard January 2013 (has links)
Mr. Eduard Němeček, MD Divorce issue and its consequences Diploma Thesis 5. Summary: This work proposes a closer look at the divorce-related topics with consequential impacts both on financial situation of divorced spouses and destinies of minor children as resulting from divorced marriages in Czech Republic. Till date, this issue has been solved in different ways at both district and regional courts. In our republic, a more unifying element is represented by decisions of the Supreme and Constitutional Courts. This is a very serious social phenomenon which, according to statistics affects a large number of parents, children, but also childless partners. Yet from ancient times this phenomenon is known to be socially undesirable being almost entirely rejected by the Catholic Church in its canon law. The increase in divorces has resulted namely from the advancement procedure of society. It is a societal phenomenon known to occur irrelatively of the states and political systems, from the totalitarian regimes through those autocratic, up to highly democratic systems of developed countries worldwide. During the creation of this work, up to 40% of marriages have been critically monitored as expected to be ended in divorce. It's a long-term social phenomenon that surpassed all political systems from the...
24

Graphene-Based Conductor Materials: Assessment of the Electrical Conductivity

Rizzi, Leo 05 August 2021 (has links)
In the application as conductor materials, metals such as copper or aluminum represent the state of the art. This applies for example to high-voltage lines, motor windings or the infrastructure in cities. However, metals, and especially copper, are expensive and heavy. Graphene-based conductor materials (GCMs) represent a cost-competitive and highly conductive alternative to metallic conductors. GCMs are mechanically flexible, lightweight and corrosion-resistant. But in order to fully exploit the potential of their electrical conductivity, a systematic material optimization is required. In this thesis, the electrical conductivity of GCMs is investigated in simulations and experiments. Using a simplified model of a GCM, the theoretical maximum value of the conductivity is derived mathematically. Furthermore, the dependence of the conductivity on microscopic material parameters is quantified. For a deeper insight, finite element simulations are used to study more realistic as well as defective geometries. The meaningful modeling of physical parameters as statistical distributions requires structures with tens of thousands of graphene flakes. To this end, an efficient network model is designed and implemented. The network model is further used to compare results with the literature, to consider surface contacts and to perform an exemplary material evaluation. From the simulation results, specific guidelines for the production of highly conductive GCMs are derived. In order to validate the simulations and to evaluate the potential of GCMs experimentally, a process chain for the preparation of graphene films is set up. Liquid graphene or graphene oxide dispersions are chosen as the starting materials, since large amounts of graphene can be processed in this way. The sizes of the graphene flakes are varied via centrifugation. Hydriodic acid is employed and evaluated as a reducing agent, as is thermal treatment. Scanning electron microscopy, Raman microscopy and an eddy current measurement of the conductivity are used for material characterization. Two studies on the dependence of the electrical conductivity on microscopic parameters are experimentally realized. The results show good agreement with the prediction by the network model and thus support the previously established theoretical description. / In der Anwendung als Leitermaterialien werden nach dem Stand der Technik Metalle wie Kupfer oder Aluminium eingesetzt. Dies betrifft beispielsweise Hochspannungsleitungen, Motorwicklungen oder die Infrastruktur in Städten. Insbesondere im Fall von Kupfer handelt es sich um ein teures und schweres Material. Graphen-basierte Leitermaterialien (GCMs, engl. graphene-based conductor materials) stellen eine potentiell günstige und hoch leitfähige Alternative dar, die metallische Leiter ersetzen kann. GCMs sind mechanisch flexibel, wesentlich leichter als Metalle und korrosionsbeständig. Um das Potential ihrer elektrischen Leitfähigkeit voll auszuschöpfen bedarf es jedoch einer gezielten Materialoptimierung. In der vorliegenden Arbeit wird die elektrische Leitfähigkeit von GCMs systematisch in Simulationen und Experimenten untersucht. Mit einem vereinfachten Modell eines GCMs wird der theoretische Maximalwert der Leitfähigkeit mathematisch hergeleitet. Weiterhin wird die Abhängigkeit der Leitfähigkeit von mikroskopischen Materialparametern quantifiziert. In Finite Elemente Simulationen werden realistischere sowie defektbehaftete Geometrien betrachtet und die Erkenntnisse aus dem analytischen Modell erweitert. Die sinnvolle Modellierung von physikalischen Eingangsgrößen als statistische Verteilungen erfordert Strukturen mit mehreren Zehntausend Graphenplättchen. Zu diesem Zweck wird ein effizientes Netzwerkmodell konzeptioniert und implementiert. Mit dem Modell werden darüberhinaus Ergebnisse mit der Literatur verglichen, Oberflächenkontakte betrachtet und eine beispielhafte Materialbewertung durchgeführt. Weiterhin werden konkrete Richtlinien zur Herstellung von hochleitfähigen GCMs abgeleitet. Um die Simulationen zu validieren und das Potential von GCMs experimentell zu bewerten, wird eine Prozesskette zur Herstellung von Graphenfilmen aufgebaut. Dabei werden flüssige Graphen- oder Graphenoxiddispersionen als Ausgangsmaterial gewählt, da in dieser Art große Mengen Graphen verarbeitet werden können. Mittels Zentrifugierung werden die Größen der Graphenplättchen variiert. Iodwasserstoffsäure wird als Reduktionsmittel eingesetzt und bewertet, ebenso wie eine thermische Materialbehandlung. Zur Materialcharakterisierung werden Rasterelektronenmikroskopie, Raman-Mikroskopie und eine Wirbelstrommessung der Leitfähigkeit eingesetzt. Zwei Studien zur Abhängigkeit der Leitfähigkeit von mikroskopischen Parametern werden experimentell realisiert. Die Ergebnisse zeigen gute Übereinstimmung zur Vorhersage durch das Netzwerkmodell und untermauern so die zuvor beschriebenen Wirkzusammenhänge.
25

Structure Property Relations and Finite Element Analysis of Ram Horns: A Pathway to Energy Absorbent Bio-Inspired Designs

Trim, M W (Michael Wesley) 06 August 2011 (has links)
A recently emerging engineering design approach entails studying the brilliant design solutions found in nature with an aim to develop design strategies that mimic the remarkable efficiency found in biological systems. This novel engineering approach is referred to as bio-inspired design. In this context, the present study quantifies the structure-property relations in bighorn sheep (Ovis canadensis) horn keratin, qualitatively characterizes the effects of a tapered spiral geometry (the same form as in a ram’s horn) on pressure wave and impulse mitigation, describes the stress attenuation capabilities and features of a ram’s head, and compares the structures and mechanical properties of some energy absorbent natural materials. The results and ideas presented herein can be used in the development of lightweight, energy absorbent, bio-inspired material designs. Among the most notable conclusions garnered from this research include: Horn keratin behaves in an anisotropic manner similar to a long fiber composite. Moisture content dominates the material behavior of horn keratin more than anisotropy, age, and stress-state. This makes moisture content the most influential parameter on the mechanical behavior of horn keratin. Tapered geometries mitigate the impulse generated by a stress wave due to the convergent boundary and a continually decreasing cross sectional area such that greater uniaxial stresses and subsequent axial deformation arises. Furthermore, the tapered geometry introduces small shear stresses that further decrease the impulse. Spiral geometries attenuate the impulse generated by a stress wave by the introduction of shear stresses along the length of the spiral. These shear stresses introduce transverse displacements that function to lessen the impulse. When both a taper and spiral geometry are used in a design, their synergistic effects multiplicatively reduce the impulse Tough natural materials have a high porosity, which makes them light-weight, while increasing their compressive energy absorption ability. Biomaterials whose functions include protection and energy absorption feature a multiscale, hierarchical, composite structure. The constituent materials are arranged in such ways to achieve a synergistic effect, where the properties of the composite exceed the properties of its constituents. Biological materials are therefore not confined to the law of mixtures.

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