Дисертації: "Octahedron"

1

Vaidya, Rohan. "Optimum Support Structure Generation for Additive Manufacturing using Unit Cell Structures and Support Removal Constraint." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490354059543447.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Artavia, Marco [Verfasser], Dieter [Akademischer Betreuer] Kirschke, Harald [Akademischer Betreuer] Grethe, and Martin [Akademischer Betreuer] Banse. "Stochastic multi-market modeling with "efficient quadratures" : Does the rotation of Stroud's octahedron matter? / Marco Antonio Artavia Oreamuno. Gutachter: Dieter Kirschke ; Harald Grethe ; Martin Banse." Berlin : Humboldt Universität zu Berlin, Landwirtschaftlich-Gärtnerische Fakultät, 2014. http://d-nb.info/1048114392/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Valle, Raciel. "Polygonal Complexes with Octahedral Links." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306345474.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Melbourne, I. "Bifurcation problems with octahedral symmetry." Thesis, University of Warwick, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383295.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Zhang, Paul S. M. Massachusetts Institute of Technology. "Octahedral fields for feature-aligned cross-fields." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/128305.

Повний текст джерела

Анотація:

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, February, 2020
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 59-61).
We present a method for designing smooth cross fields on surfaces that automatically align to sharp features of an underlying geometry. Our approach introduces a novel class of energies based on a representation of cross fields in the spherical harmonic basis. We provide theoretical analysis of these energies in the smooth setting, showing that they penalize deviations from surface creases while otherwise promoting intrinsically smooth fields. We use these new energies to generate feature-aligned cross fields and demonstrate the applicability of our method to quad-meshing.
by Paul Zhang.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Sgambellone, Mark Allan. "Photochemistry and Photophysics of Octahedral Ruthenium Complexes." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366111201.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Jupp, Kathleen M. "Dynamically sourced intensity in octahedral nickel(II) complexes." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241013.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Childers, Kevin Ronald. "Octahedral Extensions and Proofs of Two Conjectures of Wong." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5314.

Повний текст джерела

Анотація:

Consider a non-Galois cubic extension K/Q ramified at a single prime p > 3. We show that if K is a subfield of an S_4-extension L/Q ramified only at p, we can determine the Artin conductor of the projective representation associated to L/Q, which is based on whether or not K/Q is totally real. We also show that the number of S_4-extensions of this type with K as a subfield is of the form 2^n - 1 for some n >= 0. If K/Q is totally real, n > 1. This proves two conjectures of Siman Wong.

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Quarmby, I. C. "Electron-transfer reactions of octahedral manganese (I) carbonyl complexes." Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233742.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Santiso, Quiñones Gustavo. "Octahedral versus trigonal prismatic rearrangements in MoF6 and WF6 derivatives." [S.l.] : [s.n.], 2005. http://www.diss.fu-berlin.de/2005/11/index.html.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Cross, Jasmine Mary. "Synthesis and analysis of pseudo-octahedral metal complexes as anticancer agents." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12772/.

Повний текст джерела

Анотація:

Chemotherapy is one of the most predominantly used treatments for cancer. Identifying desirable features required of anticancer agents has rapidly developed alongside our growing understanding of the disease. Metal complexes are of interest as drug candidates as they provide advantages over purely organic systems via modular synthesis, variable geometries and oxidation states. Currently, platinum drugs such as cisplatin remain the most common metal-based treatments, despite their known toxicity towards healthy cells. Viable complexes are therefore sought as alternatives that overcome the limitations of platinum drugs. The synthesis and analysis of three piano-stool metal complex series are described, each investigating a distinct mechanism of action. Firstly, pyridylphosphinate complexes were employed as potential DNA-binding agents. The complexes possess a labile monodentate halide ligand, which exchanges intracellularly, forming the aqua species, enabling the binding of DNA. The metal, arene and ligand substituents were varied to tune the properties of the complexes. Of the resulting systems, few displayed notable cytotoxicity, and these complexes were pursued no further. The bulk of this thesis focusses on HDAC enzymes as a discrete target for anticancer therapy. New complexes were developed incorporating arene-metal motifs along with ligands designed to trigger HDAC inhibition. The biological properties of this series were explored and revealed moderate to good cytotoxicity, as well as HDAC inhibition to be the likely mechanism of action. Structural modifications of the parent complexes were devised to optimise selectivity between HDAC enzyme isoforms. Relative to the ligand alone, an increase in specificity of the metal-ligand complexes was observed, successfully demonstrating the benefits of incorporating a metal-arene motif. Biological assays including cellular uptake, catalytic domain selectivity and uptake mechanism are reported to examine the varied behaviour of these complexes. Hypoxic activation was the final mechanism of action studied. Two complexes were synthesised possessing a reducible protecting group, to produce the active species selectively under conditions of hypoxia. Such activity was utilised to minimise off-target binding and enhance tumour region selectivity.

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Tidwell, Paul H. "Design and construction of a double-octahedral variable geometry truss manipulator." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/74544.

Повний текст джерела

Анотація:

This thesis deals with the design and construction of a variable geometry truss (VGT) of the double-octahedral (pyramid-pyramid) geometry. The truss is expected to be the focus of several experimental research projects. In this thesis, a kinematic model is formulated, and the forward and inverse kinematic problems are solved. Issues of motor and instrumentation choices are addressed. Dimensional choices and the important problems of joint design are examined. A computer simulation is performed for force and vibration analysis. A fully collapsible double-octahedral variable geometry truss with three degrees of freedom was built using NC machining technologies. An improved second generation twenty-one degree-of-freedom truss will be built based on this original test article.
Master of Science

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Schumer, Benjamin N., Marcelo B. Andrade, Stanley H. Evans, and Robert T. Downs. "A new formula and crystal structure for nickelskutterudite, (Ni,Co,Fe)As-3, and occupancy of the icosahedral cation site in the skutterudite group." MINERALOGICAL SOC AMER, 2017. http://hdl.handle.net/10150/623060.

Повний текст джерела

Анотація:

We propose a new formula for the mineral nickelskutterudite, based on our observation that either (or both) Co or Fe3+ are essential structure constituents. The crystal structure of nickelskutterudite, (Ni,Co,Fe) As-3, cubic, Im (3) over bar, Z = 8: a = 8.2653(6) angstrom, V = 564.65(7) angstrom, has been refined to R-1 = 1.4% for 225 unique reflections I > 2 sigma(1) collected on a Bruker X8 four-circle diffractometer equipped with fine-focus, sealed tube MoKa radiation and an APEX-II CCD detector. This is the first report of the crystal structure of nickelskutterudite. Nickelskutterudite, a member of the skutterudite group of isostructural minerals, adopts a distorted perovskite structure with notably tilted octahedra and an unoccupied to partially occupied icosahedral metal site. In the structure of nickelskutterudite, there is one metal (B) site occupied by Ni, Co, or Fe in octahedral coordination with six As atoms. Procrystal electron density analysis shows each As anion is bonded to two cations and two As anions, resulting in a four-membered ring of bonded As with edges 2.547 and 2.475 angstrom. The extreme tilting of BAs6 octahedra is likely a consequence of the As-As bonding. The nickelskutterudite structure differs from the ideal perovskite structure (A(4)B(4)X(12)) in that As4 anion rings occupy three of the four icosahedral cages centered on the A sites. There are reported synthetic phases isomorphous with skutterudite with the other A site completely occupied by a cation (AB(4)X(12)). Electron microprobe analyses of nickelskutterudite gave an empirical chemical formula of (Ni0.62Co0.28Fe0.12)(Sigma 1.02)(AS(2.95)S(0.05))(Sigma 3.00) normalized to three anions. Pure NiAs3 nickelskutterudite, natural or synthesized, has not been reported. In nature, nickelskutterudite is always observed with significant Co and Fe, reportedly because all non-bonded valence electrons must be spin-paired. This suggests that nickelskutterudite must contain Co3+ and Fe2+, consistent with previous models since Ni4+ cannot spin-pair its seven non-bonded electrons, Co3+ and Fe2+, which can spin-pair all non-bonded electrons, are required to stabilize the structure. No anion deficiencies were found in the course of this study so, including the structurally necessary Co and Fe, the chemical formula of nickelskutterudite (currently given as NiAs3-x, by the IMA) should be considered (Ni,Co,Fe)As-3.

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Knapp, Meghan C. "Investigations into the structure and properties of ordered perovskites, layered perovskites, and defect pyrochlores." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1149097068.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Pelzer, Blake Patrick. "An octahedral tiling on the ideal boundary of the complex hyperbolic plane." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3854.

Повний текст джерела

Анотація:

Thesis (Ph. D.) -- University of Maryland, College Park, 2006.
Thesis research directed by: Mathematics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Boeer, Angelika. "Anisotropy in Molecular Magnetism- Magnetic Exchange Coupling of Octahedral Cobalt (II) Ions." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503050.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Matsui, Tsuneo, Takanori Nagasaki, Shunsuke Muto, Yuji Arita, Tsuyoshi Ito, Masahito Yoshino, Kazuyoshi Tatsumi, et al. "Thermoelectric properties of Ba3Co2O6(CO3)0.7 containing one-dimensional CoO6 octahedral columns." AIP, 2009. http://hdl.handle.net/2237/20785.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Simmons, Christie. "The Quantum Dynamics of H2 in a C60 Lattice." Oberlin College Honors Theses / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1125601106.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Li, Iila Jingjiao. "Flexible polyhedra : exploring finite mechanisms of triangulated polyhedra." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/271806.

Повний текст джерела

Анотація:

In a quest to design novel deployable structures, flexible polyhedra provide interesting insights. This work follows the discovery of flexible polyhedra and aims to make flexible polyhedra more useful. The dissertation describes how flexible polyhedra can be made. The flexible polyhedra first considered in this dissertation have a rotational degree of freedom. The range of this rotational movement is measured and maximised in this work by numerical maximisation. All polyhedra are established computationally: an iterative solution method is used to find vertex coordinates; several clash detecting methods are described to define whether each rotational position of a flexible polyhedron is physically possible; then a range of motion is defined between occurrences of clashes at the two ends; finally, an optimisation tool is used to maximise the range of motion. By using these tools, the range of motion of two types of simplest flexible polyhedra are maximised. The first type is a series of flexible polyhedra generalised from the Steffen flexible polyhedron. The range of motion of this type is improved to double that of Steffen’s original, from 27° to 59°. Another type of flexible polyhedron is expanded from a model provided by Tachi. Based on the understanding of Steffen’s flexible polyhedron, optimisation parameters are carefully given. This new type has achieved a wider range of motion, so now the range of motion of flexible polyhedron is tripled to 80°. After enlarging the range of motion of the degree of freedom in the 1-dof systems, the dissertation found multiple degrees of freedom in one polyhedron. The multiple mechanisms can be even repetitive, so that an n-dof polyhedron is found. A polyhedron of two degrees of freedom is first presented. Then, a unit cell for any number of mechanisms is found. As a repetitive structure, a 3-dof polyhedron is presented. Finally, this work presents the possibility of configuring a flexible polyhedral torus and a closed polyhedral surface that is able to flex without the need to stop.

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Lin, Zhijie [Verfasser], and Eric [Akademischer Betreuer] Meggers. "Asymmetric synthesis and applications of octahedral metal complexes / Zhijie Lin. Betreuer: Eric Meggers." Marburg : Philipps-Universität Marburg, 2013. http://d-nb.info/1035502313/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Sreekantan, Nair Lalithambika Sreeju [Verfasser]. "Electronic Structure of Cobalt Octahedral Complexes in Aqueous Solution / Sreeju Sreekantan Nair Lalithambika." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1190087898/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Jackson, Lee. "Some structural and physical properties of two-dimensional antiferromagnets and other octahedral structures." Thesis, University of Essex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386095.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Schott, Daniele. "NMR studies of octahedral ruthenium hydride and silyl complexes : reactivity and dynamic behaviour." Thesis, University of York, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274490.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Mansour, Saber E. (Saber El-Sayed). "The Nature of Intermediates Produced Through Ligand-Substitution Reactions of Octahedral Metal Carbonyls." Thesis, North Texas State University, 1986. https://digital.library.unt.edu/ark:/67531/metadc331634/.

Повний текст джерела

Анотація:

Pulsed laser time-resolved ligand-substitution photochemistry for (DTO)W(CO)4, (DTN)W(CO)4, and (NP)Mo(CO)4 (DTO = 2,2,7,7-tetramethyl-3,6-diathiaoctane; DTN = 2,2,8,8- tetramethyl-3,7-diathianonane; NP = l-diethylamino-2- diphenylphosphinoethane) proceeds via initial fission of the W-S and Mo-P bonds, affording Cs and C4v five-coordinate intermediates for DTN and NP but largely Cs for DTO. The rates of reaction of these intermediates, via chelate ring closure and competitive bimolecular interaction with Lewis bases (= L, alkylphosphines and alkyl phosphites) for the Cs intermediates and via bimolecular interaction of L with the C4v intermediates, together with activation parameters for these processes have been determined. The rates of interactions at the Cs intermediates are significantly faster than at the C4v intermediates.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Ashford, Neil F. "Kinetic studies of polyene exchange and substitution in low valent octahedral metal complexes." Thesis, Keele University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.716856.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Driscoll, Daniel J. "Atomistic simulation and experimental studies of complex oxide materials containing tetrahedral and octahedral units." Thesis, University of Surrey, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422906.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Eng, Hank W. "The crystal and electronic structures of oxides containing d0 transition metals in octahedral coordination." Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1070570079.

Повний текст джерела

Анотація:

Thesis (Ph. D.)--Ohio State University, 2003.
Title from first page of PDF file. Document formatted into pages; contains xx, 180 p.; also includes graphics. Includes bibliographical references (p. 139-145).

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Vlassiadi, Ekaterini [Verfasser], and Andreas [Gutachter] Hirsch. "Synthesis of Novel Fullerene Architectures with Mixed Octahedral Addition Pattern / Ekaterini Vlassiadi ; Gutachter: Andreas Hirsch." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2017. http://d-nb.info/1141381249/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Park, Chulhoon. "Parallel implementation of hierarchical tetrahedral - octahedral (HTO) subdivision for 3-D finite element mesh refinement." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99529.

Повний текст джерела

Анотація:

Parallel computing is being used more and more frequently in 3-D finite element (FE) mesh generation in electromagnetics, due to its improvements in efficiency. When applying parallel computing, the computational problem usually needs to be broken into discrete pieces, so that it can be solved simultaneously with multiple compute resources. Less time is then required than with a single compute resource. In this thesis, an algorithm for hierarchical tetrahedral---octahedral (HTO) subdivision was studied and implemented with a parallel message passing interface (MPI). The data structure was designed in such a way as to store the geometric data during the mesh computation. Also, broadcasting and data gathering was used to build up the final geometric file. The experimental results and the enhancement of system performance are presented, comparing sequential computing with parallel computing. The program was implemented in C language/MPI, and the results obtained have made use of the CLUMEQ1 supercomputer Centre facilities at McGill University.
1CLUMEQ stands for Consortium Laval UQAM McGill and Eastern Quebec for high performance computing.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Liu, Xiao-Hua. "Calamitic octahedral manganese(I) and rhenium(I) metallomesogens and side chain liquid crystalline poly(ferrocenylsilanes)." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264433.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Vlassiadi-Kasotaki, Ekaterini [Verfasser], and Andreas [Gutachter] Hirsch. "Synthesis of Novel Fullerene Architectures with Mixed Octahedral Addition Pattern / Ekaterini Vlassiadi ; Gutachter: Andreas Hirsch." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2017. http://d-nb.info/1141381249/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Yadav, Priti. "Multiscale Modelling of Proximal Femur Growth : Importance of Geometry and Influence of Load." Doctoral thesis, KTH, Strukturmekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209149.

Повний текст джерела

Анотація:

Longitudinal growth of long bone occurs at growth plates by a process called endochondral ossification. Endochondral ossification is affected by both biological and mechanical factors. This thesis focuses on the mechanical modulation of femoral bone growth occurring at the proximal growth plate, using mechanobiological theories reported in the literature. Finite element analysis was used to simulate bone growth. The first study analyzed the effect of subject-specific growth plate geometry over simplified growth plate geometry in numerical prediction of bone growth tendency. Subject-specific femur finite element model was constructed from magnetic resonance images of one able- bodied child. Gait kinematics and kinetics were acquired from motion analysis and analyzed further in musculoskeletal modelling to determine muscle and joint contact forces. These were used to determine loading on the femur in finite element analysis. The growth rate was computed based on a mechanobiological theory proposed by Carter and Wong, and a growth model in the principal stress direction was introduced. Our findings support the use of subject- specific geometry and of the principal stress growth direction in prediction of bone growth. The second study aimed to illustrate how different muscle groups’ activation during gait affects proximal femoral growth tendency in able-bodied children. Subject-specific femur models were used. Gait kinematics and kinetics were acquired for 3 able-bodied children, and muscle and joint contact forces were determined, similar to the first study. The contribution of different muscle groups to hip contact force was also determined. Finite element analysis was performed to compute the specific growth rate and growth direction due to individual muscle groups. The simulated growth model indicated that gait loading tends to reduce neck shaft angle and femoral anteversion during growth. The muscle groups that contributes most and least to growth rate were hip abductors and hip adductors, respectively. All muscle groups’ activation tended to reduce the neck shaft and femoral anteversion angles, except hip extensors and adductors which showed a tendency to increase the femoral anteversion. The third study’s aim was to understand the influence of different physical activities on proximal femoral growth tendency. Hip contact force orientation was varied to represent reported forces from a number of physical activities. The findings of this study showed that all studied physical activities tend to reduce the neck shaft angle and anteversion, which corresponds to the femur’s natural course during normal growth. The aim of the fourth study was to study the hypothesis that loading in the absence of physical activity, i.e. static loading, can have an adverse effect on bone growth. A subject-specific model was used and growth plate was modeled as a poroelastic material in finite element analysis. Prendergast’s indicators for bone growth was used to analyse the bone growth behavior. The results showed that tendency of bone growth rate decreases over a long duration of static loading. The study also showed that static sitting is less detrimental than static standing for predicted cartilage-to-bone differentiation likelihood, due to the lower magnitude of hip contact force. The prediction of growth using finite element analysis on experimental gait data and person- specific femur geometry, based on mechanobiological theories of bone growth, offers a biomechanical foundation for better understanding and prediction of bone growth-related deformity problems in growing children. It can ultimately help in treatment planning or physical activity guidelines in children at risk at developing a femur or hip deformity.

QC 20170616

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Evans, James R. "The electric field gradient of octahedral iron in layer silicates: theory with applications to Mossbauer spectroscopy." Thesis, University of Ottawa (Canada), 2001. http://hdl.handle.net/10393/22144.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Yaguchi, Momo. "The Effect of Lattice Strain in Electrochemical Oxidations Catalyzed by Au-PdPt Core-shell Octahedral Nanoparticles." Thesis, Boston College, 2012. http://hdl.handle.net/2345/2928.

Повний текст джерела

Анотація:

Thesis advisor: Chia-kuang Frank Tsung
Pt-based alloy and core-shell nanoparticles have been intensively studied to regulate its size and shape. It has known that these nanoparticles show enhanced catalytic activity in various important fields such as heterogeneous catalysis, and electrochemical energy storage including fuel cells and metal-air batteries. Here, we report a facile hydrothermal synthesis of sub-10 nm PdPt alloy and sub-20 nm Au@PdPt core-shell structures. By using a mild reducing agent in aqueous solution, metal precursors are co-reduced. Specific gases are introduced during the synthesis to optimize the reaction conditions. The PdPt alloy and Au@PdPt core-shell nanostructures were characterized and confirmed by TEM, HRTEM, EDS, ICP-OES and XRD. The resulting PdPt and Au@PdPt particles are monodispersed single crystalline and octahedral shape enclosed by (111) facets. The electrocatalytic activity for the oxidation of formic acid was tested. It was found that the catalytic activity toward the formic acid oxidation of Au@PdPt core-shell particles were much higher than those of PdPt alloy particles. In addition, Pt-rich compositions were the most active in both PdPt alloy and Au@PdPt core-shell nanoparticles. Further studies on thinner alloy-shell core-shell nanoparticles reveal that there is a volcano-curve relationship between the lattice strain strength related to alloy-shell thickness and the catalytic performance. It is proposed that there are three key parameters that can determine the catalytic activity: the alloy composition, the presence of the gold core, and the thickness of alloy-shell
Thesis (MS) — Boston College, 2012
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Lorenz, Michael, Gerald Wagner, Vera Lazenka, Peter Schwinkendorf, Hiwa Modarresi, Bael Margriet J. Van, André Vantomme, Kristiaan Temst, Oliver Oeckler, and Marius Grundmann. "Correlation of magnetoelectric coupling in multiferroic BaTiO3-BiFeO3 superlattices with oxygen vacancies and antiphase octahedral rotations." American Institute of Physics, 2015. https://ul.qucosa.de/id/qucosa%3A31214.

Повний текст джерела

Анотація:

Multiferroic (BaTiO3-BiFeO3) × 15 multilayer heterostructures show high magnetoelectric (ME) coefficients aME up to αME up to 24 V/cm·Oe at 300 K. This value is much higher than that of a single-phase BiFeO3 reference film (αME = 4.2 V/cm·Oe). We found clear correlation of ME coefficients with increasing oxygen partial pressure during growth. ME coupling is highest for lower density of oxygen vacancy-related defects. Detailed scanning transmission electron microscopy and selected area electron diffraction microstructural investigations at 300K revealed antiphase rotations of the oxygen octahedra in the BaTiO3 single layers, which are an additional correlated defect structure of the multilayers.

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Shen, Xiaodong [Verfasser], and Eric [Akademischer Betreuer] Meggers. "Octahedral Chiral-at-Metal Iridium and Rhodium Complexes as Versatile Asymmetric Catalysts / Xiaodong Shen. Betreuer: Eric Meggers." Marburg : Philipps-Universität Marburg, 2016. http://d-nb.info/1102354457/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Evans, R. James. "The electric field gradient of octahedral iron(2+) in layer silicates: Theory with applications to Moessbauer spectroscopy." Thesis, University of Ottawa (Canada), 2001. http://hdl.handle.net/10393/8968.

Повний текст джерела

Анотація:

New electronic structure calculations of the electric field gradient (EFG) at octahedral Fe2+ sites in layer silicates are discussed. These calculations were done with the aim of providing a link between quadrupole splitting distributions from Mossbauer spectroscopy and the physical distributions of local environments within the material. Various distortions were applied to FeO610- and Fe(OH)6 4- clusters to simulate different local environments and the corresponding EFG's calculated. The electronic structure calculations were performed with the General Atomic and Molecular Electronic Structure System (GAMESS) and a self-consistent-charge-Xalpha method. An analytic model of the EFG using a classical electrostatic point charge model and crystal field theory is used to complement the electronic structure calculations. There is good qualitative agreement between the electronic structure calculations, the analytic model, and with experimental quadrupole splittings in micas. A geometric model of the octahedral sheet in a layer silicate is described, based on isometric flattening and counter-rotation as the main distortions, which can have one, two, or three unique sites. EFG distributions are then calculated using a variety of cases based on the geometric model and the calculated EFG vs. distortion curves. The most realistic distribution results from a case that assumes two unique site-types in a ratio of 2:1, with the height of each site and the inter-cation distance held constant throughout the sheet and the Fe--O bond length of one site-type allowed to vary with a Gaussian distribution.

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Yoshida, Suguru. "Structure-Property Correlations in Complex Oxides with Broken Inversion Symmetry." Kyoto University, 2020. http://hdl.handle.net/2433/253287.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Grill, Nicolette Deannah. "ECONOMIC GEOLOGY OF THE SAN BERNARDINO MOUNTAINS, CALIFORNIA." CSUSB ScholarWorks, 2014. https://scholarworks.lib.csusb.edu/etd/102.

Повний текст джерела

Анотація:

The San Bernardino Mountains are well known for their rich mining history, especially, gold in the mid-1800s and the current mining of one of the world’s largest deposits of high purity limestone. The purpose of this study was to compile new, current, and historical data of the major economic resources that are present and mining that has gone on in the San Bernardino Mountains. It is estimated that historical mining of the Holcomb Valley recovered $457,660,000 of gold or about 350,000 troy ounces based on samples collected for this study and 2013 gold price. The current major geologic resource is the limestone deposits on the north slope of the San Bernardino Mountains. Presently, there are three operators: Omya, Specialty Minerals, and Mitsubishi Cement. The San Bernardino Mountains are well known for skarn gold deposits. New work indicates that the placer gold from Holcomb Valley is often of very high purity. Placer gold samples were analyzed using the scanning electron microscope and energy dispersive x-ray spectra to determine the purity of the gold. Rim and core analysis of the placer gold was used to determine if the gold was transported from its source and to give an estimate of transportation distance. Results show some of the placer gold of Holcomb Valley has been rounded and flattened by weathering and transportation with increased gold purity in the rims while other gold grains still sustain their octahedral crystalline structure. Rims range in gold purity from 84.26% to 100%, with core gold purity ranging from 79.51% to 99.79%. Gold samples were weighed, photographed, measured, and classified by shape, angularity and texture, to assess the effects of transportation. Gold weights where used to calculate an economic value of gold. Geographic Information System “GIS” was used to visually display geology, historical and current mine locations, locations of samples used in this study, and to help calculate the volume of the Holcomb Valley TsE rock unit, which is where the placer gold is deposited. Sediment sample 15 from TsE had the lowest gold value of .002 ounces per cubic yard. This value is inferred to represent the amount of gold remaining after mining. Based on this assumption and the estimated volume of TsE at 50,027,000 cubic yards, the estimated total weight of gold remaining in the deposit is about 100,000 troy ounces, with a dollar value of about $130,760,000, using gold values for 2013. Sample 17 had the highest gold value, with .014 ounces per cubic yard. This is inferred to represent the concentration of placer gold deposits within parts of Holcomb Valley that have never been mined. This yields a total weight of the deposit of roughly 700,000 troy ounces, with an estimated value of $915,320,000 using gold prices for 2013. The gold values were calculated using November 7, 2013 gold spot price of $1,307.60.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Zheng, Yu [Verfasser], and Eric [Akademischer Betreuer] Meggers. "Design of Novel Octahedral Stereogenic-at-Metal Complexes for Applications in Asymmetric Catalysis / Yu Zheng ; Betreuer: Eric Meggers." Marburg : Philipps-Universität Marburg, 2018. http://d-nb.info/1153881381/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Wang, Yifeng, Kyu Hyoung Lee, Hideki Hyuga, Hideki Kita, Katsuhiko Inaba, Hiromichi Ohta, and Kunihito Koumoto. "Enhancement of Seebeck coefficient for SrO(SrTiO_3)2 by Sm substitution: Crystal symmetry restoration of distorted TiO_6 octahedra." American Institite of Physics, 2007. http://hdl.handle.net/2237/11974.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Kavanagh, Christopher M. "Synthesis and structure-property relationships in rare earth doped bismuth ferrite." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3555.

Повний текст джерела

Анотація:

There has been significant interest in BiFeO₃ over the past decade. This interest has focused on the magnetic and electrical properties, which in the long term may prove useful in device applications. This thesis focuses on the synthesis, electrical characterisation, and structural origin of the electrical properties of rare earth doped bismuth ferrite. Two systems have been studied: BiFeO₃ doped with lanthanum and neodymium (Bi₁₋ₓREₓFeO₃ RE= La, Nd). Specific examples have been highlighted focusing on a detailed structural analysis of a lanthanum doped bismuth ferrite, Bi₀.₅La₀.₅FeO₃, and a neodymium analogue, Bi₀.₇Nd₀.₃FeO₃. Both adopt an orthorhombic GdFeO₃-type structure (space group: Pnma) with G-type antiferromagnetism. Structural variations were investigated by Rietveld refinement of temperature dependent powder neutron diffraction using a combination of both conventional “bond angle/bond length” and symmetry-mode analysis. The latter was particularly useful as it allowed the effects of A-site displacements and octahedral tilts/distortions to be considered separately. This in-depth structural analysis was complemented with ac-immittance spectroscopy using the multi-formulism approach of combined impedance and modulus data to correlate structural changes with the bulk electrical properties. This approach was essential due to the complex nature of the electrical response with contributions from different electroactive regions. The structural variations occur due to a changing balance between magnetic properties and other bonding contributions in the respective systems. This results in changes in the magnitude of the octahedral tilts, and A-site displacements giving rise to phenomena such as negative thermal expansion and invariant lattice parameters i.e., the invar effect. More specifically, analysis of Bi₀.₅La₀.₅FeO₃ highlights a structural link between changes in the relative dielectric permittivity and changes in the FeO₆ octahedral tilt magnitudes, accompanied by a structural distortion of the octahedra with corresponding A-site displacement along the c-axis; this behaviour is unusual due to an increasing in-phase tilt mode with increasing temperature. The anomalous orthorhombic distortion is driven by magnetostriction at the onset of antiferromagnetic ordering resulting in an Invar effect along the magnetic c-axis and anisotropic displacement of the A-site Bi³⁺ and La³⁺ along the a-axis. This contrasts with the neodymium analogue Bi₀.₇Nd₀.₃FeO₃ in which a combination of increasing A-site displacements in the ac-plane and decrease in both in-phase and anti-phase tilts combine with superexchange giving rise to negative thermal expansion at low temperature. The A-site displacements correlate with the orthorhombic strain. By carefully changing the synthesis conditions, a significant change in bulk conductivity was observed for a number for Bi₁₋ₓLaₓFeO₃ compositions. A series of Bi₀.₆La0.₄FeO₃ samples are discussed, where changes in the second step of the synthesis result in significantly different bulk conductivities. This behaviour is also observed in other compositions e.g. Bi₀.₇₅La₀.₂₅FeO₃. Changes in the electrical behaviour as a function of temperature are discussed in terms of phase composition and concentration gradients of defects. Activation energies associated with the conduction process(es) in Bi₁₋ₓLaₓFeO₃ samples, regardless of composition, fall within one of two broad regimes, circa. 0.5 eV or 1.0 eV, associated with polaron hopping or migration of charge via oxygen vacancies, respectively. The use of symmetry-mode analysis, in combination with conventional crystallographic analysis and electrical analysis using multi-formulism approach, presents a new paradigm for investigation of structure-property relationships in rare earth doped BiFeO₃.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

SWANSON, DALE DORSETT. "ELECTROCHEMICAL AND SPECTROSCOPIC STUDIES OF THIOETHER COORDINATION COMPLEXES (CYCLIC VOLTAMMETRY, OCTAHEDRAL LOW-SPIN METALS, BLUE COPPER PROTEINS, ELECTRON PARAMAGNETIC RESONANCE)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188102.

Повний текст джерела

Анотація:

The bis 1,4,7-trithiacyclononane (1,4,7-TTCN) complexes of iron, cobalt, nickel and copper are reported in this work. Their properties have been examined using computer-controlled electrochemical and spectroscopic techniques. These TTCN complexes form readily, are unusually symmetrical and support electron transfer reactions at the metal center. The cobalt(II) complex is octahedral, low spin and symmetrical. Four oxidation states of cobalt-TTCN complex are observed; two one-electron transfer processes are reversible. Copper (II) bis 1,4,7-TTCN is unusually symmetrical evidenced by both solid phase and ambient temperature aqueous phase electron paramagnetic resonance spectra. An unusually high redox potential for the copper complex indicates extraordinary stability of the Cu(I) oxidation state but evidently not at the expense of Cu(II) stability. The complex also has a high formation constant compared to other copper-thioether complexes. This unusual strength of thioether donor is attributed to ligand geometry. The 1,4,7-TTCN molecule is the only known cyclic polythioether to have all sulfur atoms endodentate. This structure contributes to thermodynamic stability of complexes as the ground state configuration of the free ligand is maintained in the complex.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Fu, Chen [Verfasser], and Eric [Akademischer Betreuer] Meggers. "Contributions to the Asymmetric Synthesis of Octahedral Ruthenium(II) Complexes and to Bioactive Hexacoordinate Silicon Complexes / Chen Fu. Betreuer: Eric Meggers." Marburg : Philipps-Universität Marburg, 2014. http://d-nb.info/1064097421/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Cruchter, Thomas Josef [Verfasser], and Eric [Akademischer Betreuer] Meggers. "Design, Synthesis, and Application of a Nucleophilic Octahedral Stereogenic-Only-at-Metal Iridium(III) Catalyst / Thomas Josef Cruchter ; Betreuer: Eric Meggers." Marburg : Philipps-Universität Marburg, 2018. http://d-nb.info/1156461715/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Cruchter, Thomas [Verfasser], and Eric [Akademischer Betreuer] Meggers. "Design, Synthesis, and Application of a Nucleophilic Octahedral Stereogenic-Only-at-Metal Iridium(III) Catalyst / Thomas Josef Cruchter ; Betreuer: Eric Meggers." Marburg : Philipps-Universität Marburg, 2018. http://d-nb.info/1156461715/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Pearson, David Graham. "The petrogenesis of pyroxenites containing octahedral graphite and associated mafic and ultramafic rocks of the Beni Bousera peridotite massif, n. Morocco." Thesis, University of Leeds, 1989. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442187.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Zhang, Xuesong, and n/a. "Punching Shear Failure Analysis of Reinforced Concrete Flat Plates Using Simplified Ust Failure Criterion." Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20051104.153239.

Повний текст джерела

Анотація:

Failure criteria play a vital role in the numerical analysis of reinforced concrete structures. The current failure criteria can be classified into two types, namely the empirical and theoretical failure criteria. Empirical failure criteria normally lack reasonable theoretical backgrounds, while theoretical ones either involve too many parameters or ignore the effects of intermediate principal stress on the concrete strength. Based on the octahedral shear stress model and the concrete tensile strength under the state of triaxial and uniaxial stress, a new failure criterion, that is, the simplified unified strength theory (UST), is developed by simplifiing the five-parameter UST for the analysis of reinforced concrete structures. According to the simplified UST failure criterion, the concrete strength is influenced by the maximum and intermediate principal shear stresses together with the corresponding normal stresses. Moreover, the effect of hydrostatic pressure on the concrete strength is also taken into account. The failure criterion involves three concrete strengths, namely the uniaxial tensile and compressive strengths and the equal biaxial compressive strength. In the numerical analysis, a degenerated shell element with the layered approach is adopted for the simulation of concrete structures. In the layered approach, concrete is divided into several layers over the thickness of the elements and reinforcing steel is smeared into the corresponding number of layers of equivalent thickness. In each concrete layer, three-dimensional stresses are calculated at the integration points. For the material modelling, concrete is treated as isotropic material until cracking occurs. Cracked concrete is treated as an orthotropic material incorporating tension stiffening and the reduction of cracked shear stiffness. Meanwhile, the smeared craclc model is employed. The bending reinforcements and the stirrups are simulated using a trilinear material model. To verify the correctness of the simplified UST failure criterion, comparisons are made with concrete triaxial empirical results as well as with the Kupfer and the Ottosen failure criteria. Finally, the proposed failure criterion is used for the flexural analysis of simply supported reinforced concrete beams. Also conducted are the punching shear analyses of single- and multi-column-slab connections and of half-scale flat plate models. In view of its accuracy and capabilities, the simplified UST failure criterion may be used to analyse beam- and slab-type reinforced concrete structures.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Aljaberi, Ahmed D. A. "Development and characterisation of an A-site deficient perovskite as alternative anode material for solid oxide fuel cells." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3690.

Повний текст джерела

Анотація:

The research presented in this thesis is a collection of many different, yet connected, parts that stemmed from the development of a new alternative material intended to be utilised as anode material in solid oxide fuel cells. The main part is the research conducted in the development and characterisation of the novel A-site deficient La₀.2₂Sr₀.₇₋ₓCaₓTiO₃. Calcium introduction resulted in reducing this perovskite unit cell volume which, at the beginning, enhanced its electrical conductivity in reducing conditions. However, the ideal cubic symmetry coud not be maintained, as in the starting material LA₀.₂Sr₀.₇TiO₃, as a result of the increased A-site ionic radius mismatch and two lower symmetries were observed at room temperature. These were the tetragonal I4/mcm for 0.1 ≤ x ≤ 0.35 and orthorhombic Pbnm for 0.4 ≤ x ≤ 0.7. Higher temperature NPD data showed that the orthorhombic samples transformed into higher symmetries with Pbnm → I4/mcm → Pm3-m phase transitions. Detailed crystallographic analysis is discussed; where the different unit cells showed changes to the tilts of the BO₆ octahedra, along with distortions to these octahedra. DC conductivity measurements showed a high electrical conductivity of 27.5 S/cm for a pre-reduced composition La₀.₂Sr₀.₂₅Ca₀.₄₅TiO₃ at 900°C and pO₂ = 10⁻¹⁹ atm. This material showed very encouraging features; which makes it a very promising anode material for SOFCs. A study was also done which explores the best renewable energy options for the United Arab Emirates given its local climate and other aspects. The reliance on seawater desalination is argued to by unsustainable for different reasons. Thus, water security should be a main element in the planning process for adopting renewable energy technologies. A system that combines different technologies; with a focus on fuel cells technology; is outlined which is thought of to be a very promising basis for a broader system that will secure power and water in a very environment friendly way. Different compositions of the system La₀.₂Sr₀.₇₋ₓCaₓTiO₃ were also studied using AC impedance spectroscopy in order to establish whether or not this system can show a ferroelectric behaviour. Results showed a variation in the dielectric constant of different samples with temperature; however, no Curie point was observed. Nonetheless, the results did show that the different compositions were very homogeneous when fully oxygenated and there were some indications of possible symmetry changes at sub-ambient temperatures. The final part of this thesis outlined the work done towards the development of a new analytical instrument. An existing TGA instrument was altered in order to provide a simultaneous thermogravimetric analysis and DC conductivity measurement for solid solutions at controlled temperature and oxygen partial pressure. Results were obtained for different samples of the system La₀.₂Sr₀.₇₋ₓCaₓTiO₃ which showed a great dependence of the electrical conductivity on the oxygen stoichiometry in these oxides. Also, a direct method is possible with this instrument to estimate the oxygen chemical diffusion coefficient using the electrical conductivity relaxation method. This new setup will be very useful for different electrochemical and thermal studies which can broaden the understanding of the different mechanisms that affect the performance of different solid state materials.

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Keitel, David [Verfasser]. "Improving robustness of continuous-gravitational-wave searches against signal-like instrumental artefacts and a concept for an octahedral gravitational-wave detector in space / David Keitel." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2015. http://d-nb.info/1068922990/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Дисертації з теми "Octahedron"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями