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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.
51

In-Bore Acceleration Measurements of an Electromagnetic Gun Launcher

Bukowski, Edward F., Brown, T. Gordon, Brosseau, Tim, Brandon, Fred J. 10 1900 (has links)
ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / The US Army Research Laboratory has been involved in the design and implementation of electromagnetic gun technology for the past several years. One of the primary factors of this research is an accurate assessment of in-bore structural loads on the launch projectiles. This assessment is essential for the design of mass-efficient launch packages for electromagnetic guns. If not properly accounted for, projectile failure can result. In order to better understand the magnitude of the in-bore loads, a data-recorder was integrated with an armature and on-board payload that included tri-directional accelerometers and magnetic field sensors. Several packages were launched from an electromagnetic railgun located at Aberdeen Proving Ground, MD. Substantial effort was placed on soft-catching the rounds in order to facilitate data recovery. Analysis of the recovered data provided acceleration and magnetic field data acquired during the launch event.
52

The development of an electron gun for performing ultrafast electron diffraction experiments

Erasmus, Nicolas 12 1900 (has links)
Thesis (MSc (Physics))--Stellenbosch University, 2009. / ENGLISH ABSTRACT: This thesis aims to comprehensively discuss ultrafast electron di raction and its role in temporally resolving ultrafast dynamics on the molecular level. Theory on electron pulses and electron pulse propagation will be covered, but the main focus will be on the method, equipment and experimental setup required to generate sub-picosecond electron pulses, which are needed to perform time resolved experiments. The design and construction of an electron gun needed to produce the electron pulses will be shown in detail, while preliminary pulse characterization experiments will also be illustrated. An introduction into the theory of electron diffraction patterns and how to interpret these diffraction patterns will conclude the thesis. / AFRIKAANSE OPSOMMING: Hierdie tesis het ten doel om ultravinnige elektrondi raksie deeglik te bespreek asook die rol wat dit speel om ultravinnige tyd-dinamika op 'n molekulêre vlak op te los. Die teorie van elektonpulse en die voortplanting van elektronpulse sal gedek word, maar die fokus sal op die metode, gereedskap en eksperimentele opstelling wees wat benodig is om sub-pikosekonde elektronpulse te genereer. Die ontwerp en konstruksie van 'n elektrongeweer, wat benodig word om elektronpulse te produseer, sal in detail bespreek word, terwyl aanvanklike pulskarakterisasie eksperimente ook illustreer sal word. 'n Inleiding tot die teorie van elektrondi raksie patrone en hoe om hulle te interpreteer sal die tesis afsluit.
53

The detection of concealed firearm carrying through CCTV : the role of affect recognition

Blechko, Anastassia January 2011 (has links)
This research aimed to explore whether the recognition of offenders with a concealed firearm by a human operator might be based on the recognition of affective (negative) state derived from non-verbal behaviour that is accessible from CCTV images. Since a firearm is concealed, it has been assumed that human observers would respond to subtle cues which individuals inherently produce whilst carrying a hidden firearm. These cues are believed to be reflected in the body language of those carrying firearms and might be apprehended by observers at a conscious or subconscious level. Another hypothesis is that the ability to recognize the carrier of concealed firearm in the CCTV footage might be affected by other factors, such as the skills in decoding an affective state of others and the viewpoint of observation of the surveillance targets. In order to give a theoretical and experimental basis for these hypotheses the first objective was to examine the extant literature to determine what is known about recognition of affect from non-verbal cues (e.g. facial expressions and body movement), and how it can be applied to the detection of human mal-intent. A second objective was to explore this subject in relation to the detection of concealed firearm carrying through performing a number of experimental studies. The studies employed experts, i.e. CCTV operators and mainly the lay people as participants. Also, various experimental techniques such as questionnaires and eye-tracking registration were used to investigate the topic. The results show that human observers seem to use visual indicators of affective state of surveillance targets to make a decision whether or not the individuals are carrying a concealed firearm. The most prominent cues were face, and upper body of surveillance targets, gait, posture and arm movements. The test of decoding ability did not show sufficient relationship with the ability to detect a concealed firearm bearer. The performance on the task might be view dependent. Further research into this topic will be needed to generate strategies that would support reliable detection of concealed firearm carrying through employing of related affective behavioural cues.
54

Optimization of an SRF Gun for High Bunch Charge Applications at ELBE

Lu, Pengnan 29 May 2017 (has links) (PDF)
As a cutting-edge technology for photoinjectors, SRF guns are expected to provide CW electron beams with high bunch charge and low emittance, which is critical to the development of future FELs, ERLs and 4th/5th generation light sources. However, existing research has not explored the full potential of SRF guns as predicted by theory. Currently, the research activities at ELBE focus on solving technological challenges of a 3.5 cell SRF gun as well as applying it to high-bunch-charge experiments. This thesis aims to optimize the ELBE SRF gun and the relevant beam transport for future high-bunch-charge applications at pELBE, nELBE, TELBE and CBS experimental stations. Chapter 1 describes the demands of these applications on the SRF gun in detail. Chapter 2 outlines the development of a simulation tool based on ASTRA and Elegant, followed by the optimized gun parameters and the beam transport for the four experimental stations. Chapter 3 introduces beam diagnostic methods and data processing applied in this thesis. Chapter 4 presents results of experiments, including the pulse length measurement of the UV laser for generating electrons from the photcathode, the commissioning of ELBE SRF Gun II, a verification experiment on the LSC effect conducted at PITZ and a beam transport experiment with the bunch charge of 200 pC. Simulation results have determined the effect of each SRF gun parameter on the beam quality and have provided optimized settings according to the requirements in Chapter 1. Experimentally, the LSC effect was confirmed at PITZ, in agreement with simulations which indicated that LSC significantly influences beam quality. The performance of ELBE SRF Gun II was improved and a beam with a bunch charge of 200 pC and an emittance of 7.7 μm from ELBE SRF Gun II has been transported through ELBE without visible beam loss. The development of the simulation tool and beam diagnostics will serve further research at ELBE. Results of both simulations and experiments enrich the understanding of the existing SRF gun as well as the ELBE beamline and will guide continuing improvements. Already, ELBE SRF Gun II can deliver twice the bunch charge and lower emittance compared to the thermionic injector routinely used for ELBE. Ongoing modifications and development of the gun-cavity and photocathodes are expected to provide still further improvements. Progress on high-bunch-charge experiments at ELBE can be expected by applying the SRF gun.
55

Analýza statických a dynamických způsobů střelby / Analyzis of static and dynamic of shooting

Szmek, Patrik January 2012 (has links)
Title: Analyzis of static and dynamik of shooting Objectives:. Epp, ppc, ipsc, los Methods: V práci bylo zaměřeno na porovnání jednotlivých disciplín a porovnání a ovlivňování jednotlivých typů střelby. Results: Ukázalo se a také potvrdilo, že jestliže chce střelec dosahovat vynikáních výsledku, musí se prioritně zaměřit na jeden druh střelby, nejlépe na určitou disciplínu. Keywords: shouting, gun, training, difference, deportment
56

Analýza statických a dynamických způsobů střelby / Analyzis of static and dynamic of shooting

Szmek, Patrik January 2013 (has links)
Title: Analyzis of static and dynamik of shooting Objectives:. Epp, ppc, ipsc, los Methods: V práci bylo zaměřeno na porovnání jednotlivých disciplín a porovnání a ovlivňování jednotlivých typů střelby. Results: Ukázalo se a také potvrdilo, že jestliže chce střelec dosahovat vynikáních výsledku, musí se prioritně zaměřit na jeden druh střelby, nejlépe na určitou disciplínu. Keywords: shouting, gun, training, difference, deportment
57

Gun Violence and Gun Sense

Bernard, Julia M., Copp, Martha, Powers, Vicki 15 March 2017 (has links)
The panelists will be sharing information about gun violence in the U.S, proposed firearm legislation in Tennessee, research examining gun violence patterns in other states, and education to help parents and others prevent unintentional shootings by children.
58

The Second Amendment: A States’ Right, for the People, Protected by the Federal Government

Hardwick, Marie 01 January 2019 (has links)
This thesis explores the creation of the Second Amendment and how it has been interpreted over time. The purpose of this thesis is to understand present-day debates over gun control and offer an interpretation of the right that best suits the modern era. By analyzing the history of gun ownership in the United States, it is clear that the intention of the Second Amendment was to extend the right to the individual and should not be limited to collective use. As the Bill of Rights was extended to protect the people from state governments, the history of states’ rights in the regulation of firearms should be taken into account. With a country divided in their views on gun control policy, states should maintain the power to regulate arms, with federal courts intervening only when legislation is particularly radical. This thesis offers an interpretation of the Second Amendment best suited for the nation on both historical and practical by investigating the most prominent debates today: individual vs. collective rights, federal vs. states’ rights. With all things considered, this thesis concludes the most suitable interpretation of the Second Amendment for the people is: a right of the people protected, as individuals, from federal infringement, and regulated by the states, that are checked by the federal courts only when deemed necessary.
59

Teacher-centred Classrooms and Passive Resistance: Implications for Inclusive Schooling

Sium, Bairu 07 January 2013 (has links)
This thesis is based on an ethnographic study conducted in a split grade five and six classroom in Toronto during the 1985/86 academic year. Data were collected through participatory observation, as well as through individual and focus group interviews. A group of eight activist African-Canadian high school students, as well as 26 Euro- Canadian “drop-backs” were also interviewed. The time during which I conducted the study was a period of intensive education activism of parents and the community in Toronto. I was interested in determining whether or not, and this activism was reflected at the school level, and if it was reflected, how. I also wanted to examine whether or not the historically supportive auxiliary role that parents played during this period was elevated to more substantive and meaningful active involvement in the education of their children during the last half of the 1980s. This study shows that activities in the classroom were driven by pre-packaged curriculum materials and were implemented with very few modifications. Coupled with teacher-centred practice, this closed the door for any diversifying opportunities that could have found their way into the classroom, not only from the homes of the children and the school community, but also from critics of the use of prepackaged material and, most importantly, from the students themselves. Furthermore, teacher-centred classroom discourse pushed students to develop a cynical attitude towards schooling. Having no say in what or how they were taught provided the children with few choices but to develop a coping mechanism of passive resistance. Their short-term survival strategies included appearing as though they were striding along, but not embracing their school experiences fully. By the same token, they were not challenged to think critically, to evaluate or to problem-solve. A link was also established between the students’ passive resistance at the elementary level with ‘fading out’ or ‘dropping out’ and successful resistance at the high school level.
60

Experimental investigation of the effects of electrical currents in small-scale contact regimes

Manley, Matthew Halperin 01 November 2011 (has links)
Railguns undergo excessive wear between the projectile and the electromagnetic launcher rails due to the hypersonic relative motion and very large current density involved. The wear effects at the small-scale on the rail-armature interface are not well known but need to be examined in order to support the development of a multishot launcher. Proposed contact regimes in the surface asperity interactions include solidsolid contact, liquid-metal lubricated contact, and arcing. In the present work, a modified Mesoscale Friction Tester (MFT) equipped with a probe and substrate was used to investigate experimentally the arcing and friction conditions that the rail-armature interface would experience. Copper probes with a range of radii of curvature were electrochemically etched and polished to submicrometer roughness. The minimum electrode distances for arcing to occur was found in air at atmospheric pressure and led to a modified Paschen curve where field emission of electrons was the dominant physical mechanism as opposed to Townsend avalanche of ionized gas. Arcing erosion was studied by varying the current, number of strikes, dwell time, and nearest electrode positions horizontally and vertically. Copper-copper friction with a constant normal force resulted in reduced wear when applying a constant current between the electrodes. / text

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