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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.
211

Vliv tonizace v rozcvičení na výkon u florbalistů / Effect of toning in warm-up on performance of floorball players

Králíčková, Kateřina January 2019 (has links)
Title: Effect of toning in warm-up on performance of floorball players Objectives: Find out the influence of toning in warm-up before performance in exercises aimed at determining the action speed, explosive power of legs and agility of floorball players. Methods: A total of 20 floorball player aged 17 - 27 years participated in two measurements, one week apart. On the test day each proband passed one of two types of warm-up, non-toning warm-up and toning warm-up, and the next test day passed the second type of warm-up. The warm-up was follwed by three tests, the 20 m run, the jump from place and the shuttle run. For analysis of results was used statistics methods. Results: The first hypothesis was confirmed for the group of probands aged 17-19 years in the overall performance, 10 m run, 20 m run and jump from place. The second hypothesis was confirmed in the overall performance for all probands, then for the group of probands aged 17-19 years and for the group of probands aged 20-24 years. The second hypothesis was confirmed in the 10 and 20 m run for all probands, in the 10 m, 20 m run and in the jump from the place for the group of probands aged 17-19 years, in the 10 and 20 m run for group of probands aged 20-24 years. According to Cohen's d the results of the 10 and 20 m run were the most...
212

De(ter)mined? A Qualitative Research of Gender Mainstreaming Practices in Humanitarian Mine Action in Ukraine

Gajan, Sophia Katharina January 2021 (has links)
Ukraine belongs to the most landmine contaminated countries in the world. Therefore, humanitarian mine action (HMA) is an important area of work for Ukraine’s humanitarian protection cluster. In Ukraine, landmine contamination produces gendered insecurities and vulnerabilities. Casualties are predominantly men, while the affected population has a high proportion of vulnerable people, including women, the elderly, displaced and the disabled.  This study investigates which strategies were applied by organisations in the Ukraine’s mine action sub-cluster in order to respond to gendered insecurities and vulnerabilities to landmine contamination and by empowering vulnerable groups through their programmes. It is based on semi-structured interviews with representatives of HMA operators and international organisations in Ukraine. The main findings are that HMA operators in Ukraine considered gender and diversity to reach marginalised groups for operational purposes, such as internally displaced people (IDPs) and the elderly, by conducting household visits and deploying diverse teams. While operators adopted an evidence-based approach to explosive ordnance risk education (EORE), programmes predominantly focused on children, despite the largest at-risk group being adult men. More than in operations, gender mainstreaming was visible in operators’ efforts to offer equal employment opportunities in the HMA sector, supporting the affected population socio-economically. However, for meaningful participation in decision making in the sector, more time and continuous effort is required to help women advance even further into senior roles of impact.  Challenges to adequately mainstream gender were the lack of a centralised information management system and difficulties accessing the affected population. Particularly since early 2020, gender mainstreaming in community interaction has been severely limited due to COVID-19 related contact restrictions. Technological solutions were identified as the main opportunity for continued community interaction and EORE amid these access restrictions.
213

Silová tonizace v softballu žen / Power tonisation in women's softball

Pfeifer, Jan January 2021 (has links)
Title: The force toning in women's softball Objectives: The aim of this study was to demonstrate post-activation potentiation (PAP) following the muscle toning during the strenght training. The toning effect on upper limb explosive force was analyzed following application of two different degrees of resistence. Methods: In this study, we applied randomized selection for the subject to minimize the effect of possible ambiguities such as gender, training status, and player maturity. A homo- -geneous group of well-trained women with the most developed technical response was accepted. (Czech national team, Women's softball). We used the contrast method, where the data were analyzed to determine the effect of different resistance degrees and a fixed rest interval for the strength-dynamic exercise. It is a sticking out of medicine ball in sitting position, which was performed by women of the highest player level. The measurement was processed by using the direct method of dynamic efforts. We compared the explosive force with a medicine ball sticking forward in relation to the distance of the sticking medicine ball by the tested person. Results: The measurement has shown that the PAP generated by toning protocol has a sig- -nificant impact on enhancing the response in explosive drills. The exercise for...
214

INVESTIGATION OF CHEMISTRY IN MATERIALS USING FIRST-PRINCIPLES METHODS AND MACHINE LEARNING FORCE FIELDS

Pilsun Yoo (11159943) 21 July 2021 (has links)
The first-principles methods such as density functional theory (DFT) often produce quantitative predictions for physics and chemistry of materials with explicit descriptions of electron’s behavior. We were able to provide information of electronic structures with chemical doping and metal-insulator transition of rare-earth nickelates that cannot be easily accessible with experimental characterizations. Moreover, combining with mean-field microkinetic modeling, we utilized the DFT energetics to model water gas shift reactions catalyzed by Fe3O4at steady-state and determined favorable reaction mechanism. However, the high computational costs of DFT calculations make it impossible to investigate complex chemical processes with hundreds of elementary steps with more than thousands of atoms for realistic systems. The study of molecular high energy (HE) materials using the reactive force field (ReaxFF) has contributed to understand chemically induced detonation process with nanoscale defects as well as defect-free systems. However, the reduced accuracy of the force fields canalso lead to a different conclusion compared to DFT calculations and experimental results. Machine learning force field is a promising alternative to work with comparable simulation size and speed of ReaxFF while maintaining accuracy of DFT. In this respect, we developed a neural network reactive force field (NNRF) that was iteratively parameterized with DFT calculations to solve problems of ReaxFF. We built an efficient and accurate NNRF for complex decomposition reaction of HE materials such as high energy nitramine 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX)and predicted consistent results for experimental findings. This work aims to demonstrate the approaches to clarify the reaction details of materials using the first-principles methods and machine learning force fields to guide quantitative predictions of complex chemical process.
215

UNDERSTANDING THE DECOMPOSITION PROCESSES OF HIGH-ENERGY DENSITY MATERIALS

Michael N Sakano (11173161) 23 July 2021 (has links)
<div>For decades, the response of high-energy (HE) density materials at extreme conditions of pressure and temperature from strong insults like burning or impact have been studied in depth by the shock community. Shock physicists aim to develop a fundamental understanding for coupled chemical and physical processes across orders of magnitude spatial and temporal regimes. In order to succeed, this requires extensive collaboration between experiments and simulations, ranging from the electronic to the engineering scales. The end goals would be to develop predictive multiscale models capable of explaining ignition and initiation of HE systems and composites. The collected works in this thesis detail my contributions to the field of HE materials, specifically addressing the chemical reactivity at the atomistic level using reactive molecular dynamics (MD) simulations.</div><div><div>Through this endeavor, we aim to develop a critical understanding for the decomposition processes of HE materials. We begin with a validation the reactive force field, ReaxFF, by addressing the very strong anisotropic shock sensitivity in 2,2-Bis[(nitrooxy)methyl]propane-1,3-diyl dinitrate (PETN) through direct comparison of time-evolved spectra between experiments and simulations. Such strong orientation dependence is thought to relate to the initial decomposition events. Therefore we compare spectra at three different shock pressures, where we observe similar timescales for the disappearance of the NO2 symmetric and antisymmetric stretch modes. A more detailed chemical species analysis indicates that the NO2 molecular species could be considered the primary intermediate which initiates the decomposition process. Furthermore, these results suggest that the combination of explicit MD simulations and ultrafast spectroscopy will be key to the development of a detailed understanding of chemistry at extreme conditions.</div></div><div><div>Following the validation study, we further our understanding of reactivity in HE systems by investigating the differences in kinetics between an ordered and disordered system. It has been shown that shocked material is often severely strained, causing a loss in crystalline order. This in turn results in the disordered materials, such as amorphous solids, having</div><div>faster reactivity due to their higher internal energy and/or lower thermal conductivity. Our results indicate that extra energy is required to break the long-range order in bulk crystalline systems, thus resulting in slower decomposition rates. Further analyses of thermal hotspots point towards slightly faster chemical propagation in the amorphous samples due to lower thermal conductivity. These results provide an understanding for how molecular disorder can be attributed to increased reactivity.</div></div><div><div>After developing an understanding for the initial decomposition processes of HE materials, we turn our attention to a growing interest in the community which is the developing reduced order chemistry models for use in multiscale efforts. Many schemes report mechanisms that are obtained from experiments, which can have large error bars depending on the apparatus and/or extraction technique, or from gas phase simulations, which may not be relevant at shock conditions. To circumvent these issues, we develop a coarse-grained chemical kinetics model from all-atom reactive MD simulations by taking advantage of an unsupervised dimensionality reduction machine learning technique called non-negative matrix factorization. Doing so allows us to represent the overall decomposition chemistry as latent concentrations akin to reactants, intermediates, and products, which we then use to extract kinetics parameters and heats of reaction. These values are implemented into a continuum model, where we could simulate the criticality of thermal hotspots at regimes beyond the reach of MD, as well as verify how uncertainties in the parameters vary as a function of hotspot sizes.</div></div><div><div>Finally, we close with significant progress made towards on-going and future work, where we address two of the most challenging ideas in the field of HE materials: 1) developing definitive chemistry models at extreme conditions, and 2) improving coarse-grained descriptions for multiscale modeling.</div></div>
216

Walking the Ridge of the Whorl

Naimon, David 24 June 2019 (has links)
In 2010, my wife and I were harmed in a bombing while traveling in India. Over a thousand people were attending the outdoor Hindu ceremony along the Ganges in Varanasi but when I woke up in the rubble no one was there. I searched for my wife amidst the concrete debris, found her unconscious, roused her, and we fled. This thesis is an examination of that gap in my experience, that unlived and unknown lapse of time-- between the moment I was blown off my feet by the blast wind until I stood up again-- and how it has reshaped my life. Circling that gap, a gap now filled with surrogate memories (e.g. others' accounts of the stampede after the explosion, photos of the destruction that we never saw first-hand), this thesis looks at the history that my wife and I unwittingly stumbled into, of the Babri Mosque and the Hindu-Muslim cycle of violence surrounding its existence, its destruction and the destruction's aftermath. Mainly, however it is about the marriage of two bombing victims, two bombing victims who have nearly the same physical injuries and thus for years have fooled themselves into believing they understand what the other is going through. It circles not only the unlived bombing "experience" but also the unspoken differences between how they've both been affected by the trauma. Blast wind physics, ear anatomy and physiology (the main site of their injuries), trauma research, and Hindu, Muslim and Buddhist history and comsology are all used in service of this investigation.
217

Conception et développement d'un micro détonateur électrique intégrant des nanothermites pour l'amorçage par impact d'explosifs secondaires / Design and development of a micro electrical detonator integrating nanothermites for impact ignition of secondary explosives

Glavier, Ludovic 13 January 2017 (has links)
Les systèmes pyrotechniques sont des éléments clés pour la réussite de la mise en orbite des satellites. Ils permettent de réaliser des fonctions vitales pour la phase de vol d'un lanceur spatial comme l'allumage des moteurs, la séparation d'étages ou la neutralisation. L'actionnement de ces systèmes pyrotechniques nécessite différents effets pyrotechniques comme la génération d'une flamme, d'une grande quantité de gaz et une onde de choc. Ces travaux de thèse interviennent à la suite d'une précédente thèse sur la conception d'un initiateur intelligent et sécurisés permettant de générer une flamme et une grande quantité de gaz mais pas une onde de choc, indispensable dans la réalisation de certaines fonctions pyrotechniques comme la séparation d'étages ou la neutralisation. L'initiateur est piloté par commandes numériques, il dispose d'un stockage local d'énergie, d'une barrière de sécurité mécanique, et d'un PyroMEMS permettant de convertir un signal électrique en un signal pyrotechnique. Cet initiateur est conçu pour remplacer les systèmes pyrotechniques actuellement utilisés sur Ariane 5 car ils sont lourds, encombrants, ils contiennent une grande quantité de substance pyrotechnique augmentant les coûts de fabrication et de stockage, pour finir, les détonateurs et les lignes de transmissions contiennent du plomb dont l'obsolescence est programmé par la réglementation Européenne REACh. L'objectif de ces travaux de thèse est de concevoir et de développer la fonction détonation à partir d'un PyroMEMS contenant moins de 50 µg de nanothermite Al / CuO dans un volume inférieur à 0,83 cm3. Après l'étude des méthodes d'amorçage d'explosif secondaire et de l'état de l'art des détonateurs existant, nous avons conçu une architecture fonctionnant sur la propulsion d'un projectile créant une onde de choc par impact. Le développement de cette fonction détonation a permis d'étudier le comportement de différentes nanothermites (Al / CuO, Al / Bi2O3, Al / MoO3 et Al / PTFE) dans l'optique de propulser le projectile. Un modèle de balistique intérieure est développé avec la combustion de nanothermite Al / Bi2O3 dopé avec du PTFE permettant de conclure qu'il n'est pas possible d'utiliser des nanothermites pour amorcer par impact un explosif secondaire tel que le RDX. Un système de propulsion basé sur la combustion du RDX initié par nanothermite est alors développé avec une étude de l'influence des paramètres dimensionnels. La réalisation d'un démonstrateur final qui permet d'amorcer en détonation du RDX démontre la faisabilité d'un tel dispositif et permet de valider des choix de conception. / Pyrotechnic systems are the keys for satellite launching on orbit. Those systems are used for engines ignition, stage separation and self-destruction. To activate those functions, different kinds of initiators are used to generate a flame, pressure from gas expansion and a shock wave. This work involved following a previous thesis on the design of a smart and safe initiator able to generate a flame and pressure form gas expansion but not a shock wave which is essential in achieving certain functions on launcher as stage separation or neutralization. The initiator is controlled by digital controls, it contain local energy source, a mechanical safety barrier and a PyroMEMS for electro-pyrotechnical conversion. This initiator is design to replace Ariane 5 current pyrotechnic systems because they are heavy, bulky, they contain a large amount of pyrotechnic substance increasing the cost of manufacturing and storage. Also detonators and transmission lines contain lead banned by the European REACh. The goal of these thesis works is to design the detonator function from the flame generated by the PyroMEMS containing 50 µg of Al / CuO nanothermite in a volume less than 0,83 cm3 without primary explosive. After the study of secondary explosive priming methods and the state of art of existing detonators, we designed an architecture running on propelling a projectile creating a shock wave through impact. The development of this detonation function was used to study the behavior of different nanothermites (Al / CuO, Al / Bi2O3, Al / MoO3 and Al / PTFE) with a view to propel the projectile. An interior ballistic model is developed with the combustion nanothermite Al / Bi2O3 doped with PTFE to conclude that it is not possible to use nanothermites to ignite in detonation by impact, by a shock to Detonation Transition) a secondary explosive such as RDX. A propulsion system based on the combustion of RDX initiated by nanothermite is then developed with a study of the influence of dimensional parameters. Achieving a final demonstrator allows to ignite in detonation RDX demonstrates the feasibility of such a device and to validate design choices.
218

Nanoplasmonic efficacy of gold triangular nanoprisms in measurement science: applications ranging from biomedical to forensic sciences

Liyanage, Thakshila 12 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Noble metal nanostructures display collective oscillation of the surface conduction electrons upon light irradiation as a form of localized surface plasmon resonance (LSPR) properties. Size, shape, and refractive index of the surrounding environment are the key features that control the LSPR properties. Surface passivating ligands on to the nanostructure can modify the charge density of nanostructures. Further, allow resonant wavelengths to match that of the incident light. This unique phenomenon called the “plasmoelectric effect.” According to the Drude model, red and blue shifts of LSPR peak of nanostructures are observed in the event of reducing and increasing charge density, respectively. However, herein, we report unusual LSPR properties of gold triangular nanoprisms (Au TNPs) upon functionalization with para-substituted thiophenols (X-Ph-SH, X = -NH2, -OCH3, -CH3, -H, -Cl, -CF3, and -NO2). Accordingly, we hypothesized that an appropriate energy level alignment between the Au Fermi energy and the HOMO or LUMO of ligands allows the delocalization of surface plasmon excitation at the hybrid inorganic-organic interface. Thus, provides a thermodynamically driven plasmoelectric effect. We further validated our hypothesis by calculating the HOMO and LUMO levels and work function changes of Au TNPs upon functionalization with para-substituted thiol. This reported unique finding then utilized to design ultrasensitive plasmonic substrate for biosensing of cancer microRNA in bladder cancer and cardiovascular diseases. In the discovery of early bladder cancer diagnosis platform, for the first time, we have been utilized to analyze the tumor suppressor microRNA for a more accurate diagnosis of BC. Additionally, we have been advancing our sensing platform to mitigate the false positive and negative responses of the sensing platform using surface-enhanced fluorescence technique. This noninvasive, highly sensitive, highly specific, also does not have false positives techniques that provide the strong key to detect cancer at a very early stage, hence increase the cancer survival rate. Moreover, the electromagnetic field enhancement of Surface-Enhanced Raman Scattering (SERS) and other related surface-enhanced spectroscopic processes resulted from the LSPR property. This dissertation describes the design and development of entirely new SERS nanosensors using a flexible SERS substrate based on the unique LSPR property of Au TNPs. The developed sensor shows an excellent SERS activity (enhancement factor = ~6.0 x 106) and limit of detection (as low as 56 parts-per-quadrillions) with high selectivity by chemometric analyses among three commonly used explosives (TNT, RDX, and PETN). Further, we achieved the programmable self-assembly of Au TNPs using molecular tailoring to form a 3D supper lattice array based on the substrate effect. Here we achieved the highest reported sensitivity for potent drug analysis, including opioids and synthetic cannabinoids from human plasma obtained from the emergency room. This exquisite sensitivity is mainly due to the two reasons, including molecular resonance of the adsorbate molecules and the plasmonic coupling among the nanoparticles. Altogether we are highly optimistic that our research will not only increase the patient survival rate through early detection of cancer but also help to battle the “war against drugs” that together are expected to enhance the quality of human life.
219

Betony s vyšší odolností vůči působení vysokých teplot / The concrete with a higher resistance to high temperatures

Mikulinec, David January 2012 (has links)
The result of this master’s thesis is acquaintance with the issues of cement concrete resistance to high temperatures. This work describes the processes ongoing in the structure of concrete at extreme thermal loads and analysis of effects of high temperatures on the individual components of reinforced concrete structures is given, then influence of high temperatures and fire on the aggregates, matrix, reinforcement steel and the resulting changes in their properties. In the experimental part is given design of composition of concrete with a higher resistance to high temperatures and subsequent verification of the physico-mechanical properties of sample of concrete after exposure to temperatures at intervals of 200 ° C, 400 ° C, 600 ° C and 900 ° C. In individual recipes were observed changes of volume weight, changes of compressive strength and tensile strength flexural , tensile strength of surface layers and the occurrence of cracks and then were compared the results of thermally loaded and unloaded samples. The benefit in this issue is to evaluate the surface appearance of samples after heat load - study of area of crack and measurement of their width - was used according to the methodology's authors Xing, Hebert, Noumowe a Ledesert given in Cement and Concrete Research. This methodology allows to quantify changes of surface, after temperature load.
220

PHASE FIELD CRYSTAL STUDIES OF STRAIN-MEDIATED EFFECTS IN THE THERMODYNAMICS AND KINETICS OF INTERFACES

Stolle, Jonathan F. E. 04 1900 (has links)
<p>In this dissertation, the Phase Field Crystal (PFC) Method is used to study a number of problems in which interfaces and elastic effects play important roles in alloys. In particular, the three topics covered in this work are grain boundary thermodynamics in alloys, dislocation-mediated formation of clusters in binary and ternary alloys, and solutal effects in explosive crystallization. Physical phenomena associated with grain boundaries, such as Read-Shockley-like behaviour and Gibbs adsorp- tion theorem, were shown to be accurately captured in both PFC- and XPFC-type models. In fact, a connection between the solute segregation behaviour and physical properties of the system—such as energy of mixing, mismatch, and undercooling—were shown. Also, grain boundary premelting was investigated. It was shown how solute can change the disjoining potential of a grain boundary and a mechanism for hysteresis in grain boundary premelting was discussed. Regarding the phenomenon of cluster formation, a general coexistence approach and a nucleation-like approach were used to describe the mechanism consistently with observations; the process is facilitated by lowering the energy increase associated with it. The final phenomenon studied was explosive crystallization. It was shown that the temperature oscillations due to unsteady motion of an interface could be captured with PFC-type models and that this behaviour leaves patterns, such as solute traces, in the material. The versatility of this PFC formalism was demonstrated by capturing the underlying physics and elucidating the role of misfit strain in altering interface oscillations during explosive crystallization. Finally, it was demonstrated in all projects how PFC model parameters relate to coarse-grained material properties, thereby connecting these phenomena on larger scales to atomistic-scale properties.</p> / Doctor of Philosophy (PhD)

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