Att använda maskininlärning för att detektera vapen eliminerar en konstant mänsklig övervakning, vilket också kan leda till en lägre responstid till polis. I den här rapporten undersöks hur en vapendetektor kan konstrueras och byggas som en del av en klient-server-lösning. / With the progress of deep learning methods the last couple of years, object detectionrelated tasks are improving rapidly. Using object detection for detecting guns in schoolsremove the need for human supervision and hopefully reduces police response time. Thispaper investigates how a gun detection system can be built by reading frames locally andusing a server for detection. The detector is based on a pre-trained SSD model and throughtransfer learning is taught to recognize guns. The detector obtained an Average Precisionof 51.1% and the server response time for a frame of size 1920 x 1080 was 480 ms, but couldbe scaled down to 240 x 135 to reach 210 ms, without affecting the accuracy. A non-gunclass was implemented to reduce the number of false positives and on a set of 300 imagescontaining 165 guns, the number of false positives dropped from 21 to 11.

With the progress of deep learning methods the last couple of years, object detection related tasks are improving rapidly. Using object detection for detecting guns in schools remove the need for human supervision and hopefully reduces police response time. This paper investigates how a gun detection system can be built by reading frames locally and using a server for detection. The detector is based on a pre-trained SSD model and through transfer learning is taught to recognize guns. The detector obtained an Average Precision of 51.1% and the server response time for a frame of size 1920 x 1080 was 480 ms, but could be scaled down to 240 x 135 to reach 210 ms, without affecting the accuracy. A non-gun class was implemented to reduce the number of false positives and on a set of 300 images containing 165 guns, the number of false positives dropped from 21 to 11.

The Multiple Streams model developed by John Kingdon (1995) and Nikolaos Zahariadis (2007) provides a valuable framework for understanding the nature of policy change. This investigation draws extensively upon the Multiple Streams framework in order to understand the development of gun-control policy initiatives under President Barack Obama. The investigation uses a case-study approach with in-depth analysis of four different mass-shooting events that took place in the United States between 2009 and 2012. Reconstruction of the shooting events and detailed parsing of the Obama administration’s official responses to each incident, when viewed through the Multiple Streams lens, clearly explain why Obama’s aggressive policy initiative was so delayed in its emergence in spite of several shootings and the President’s clearly stated belief that gun-reform was a necessary step for the federal government. While the term “policy change” is broad and may encompass all sorts of governmental responsiveness, the term herein should be interpreted in the narrowest sense: exclusively encompassing legislative initiatives. Ultimately, the investigation concludes that numerous factors, but most prominently concerns about the timing and results of the 2010 Midterm and 2012 General Elections, prevented an aggressive pursuit of gun-reform prior to January 2013. The tragic shooting of 28 people in Newtown, Connecticut, then served as a prime focusing event for the President to aggressively engage a long-standing goal.

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Neste trabalho analisa-se o problema do transporte do feixe de elétrons em canhões de elétrons, estruturas periódicas de ímãs permanentes e em coletores de simples e múltiplos estágios. Essa análise é de relevância em projetos de dispositivos de micro-ondas de potência dos tipos amplicador klystron e válvula TWT. Determina-se a dinâmica das partículas a partir da solução da equação da trajetória que é derivada da força de Lorentz e da conservação de energia. A equação da trajetória obtida é diferencial de segunda ordem, não-linear e independentemente do tempo para o potencial generalizado. Utiliza-se o método de Runge-Kutta de 4a Ordem para integrar a equação da trajetória das partículas. Obtém-se o potencial escalar elétrico a partir da solução da equação de Poisson. Numericamente, obtêm-se os po- tenciais escalares elétricos e magnéticos, por meio do Método de Elementos Finitos (MEF). Ao longo do movimento de uma partícula, obtida a partir da solução da equação da trajetória, deposita-se carga elétrica. Utilizam-se macropartículas, uma vez que é praticamente impossível modelar cada partícula do problema, a partir do método Partícula na Célula (Particle in Cell - PIC). Neste caso, tem-se um problema acoplado para o potencial escalar elétrico e as trajetórias das macropartículas, uma vez que, as trajetórias das macropartículas dependem dos potenciais e estes, por sua vez, dependem das trajetórias. À convergência deste problema acoplado utiliza-se o Método das Aproximações Sucessivas (MAS). A plataforma desenvolvida, baseada nos métodos acima, compõe-se de duas ferramentas computacionais. A primeira, XMGUN, dedica-se ao projeto de: canhões de elétrons com grades e grades de sombreamento; e coletores de simples e múltiplos estágios considerando, ainda, a emissão de elétrons secundários. A segunda, XMAGUN, volta-se ao projeto de estruturas periódicas com ímãs permanentes. Afere-se o desempenho da ferramenta computacional XMGUN com o diodo plano de Pierce operando na condição em que a corrente é limitada pelas cargas espaciais. Por sua vez, verica-se o desempenho do XMAGUN por meio de simulações com estruturas do tipo PPM separadas pelo vácuo e na presença de pole pieces. Os resultados obtidos em todas as simulações convergiram satisfatoriamente para as soluções analíticas. Utilizando o XMGUN, projeta-se um canhão de elétrons com 30 kV de tensão de anodo e uma perveância de 1,37 Perv com capacidade de fornecer uma corrente elétrica de 7,1 A. Esse canhão tem uma malha com 2796 elementos e 5057 nós. As principais características geométricas do canhão de elétrons são: raio do catodo rc=14,6 mm; raio do disco do catodo rk =6,2 mm; e ângulo do eletrodo de focalização = 37. Neste caso, a velocidade transversal normalizada e o alcance do feixe zw observados são de 0,068 e 26,88 mm respectivamente. Obtém-se uma concordância superior a 93% em corrente e perveância com o EGUN. Utilizando, ainda, o XMGUN, são simulados coletores de simples e múltiplos estágios. O coletor de simples estágio apresenta 1612 nós e 2969 elementos, e o de 4 (quatro) estágios, 2496 nós e 4257 elementos. As tensões dos eletrodos do 1o, 2o, 3o e 4o estágio são de 9,45 kV, 8,65 kV, 6,45 kV e 3,45 kV respectivamente. Durante as simulações, devido à emissão de elétrons secundários, observa-se, para o coletor de simples estágio, macropartículas penetrando na região de deriva, fenômeno este indesejado, e não observado para o coletor de 4 (quatro) estágios. Considerando o XMAGUN, projeta-se um arranjo periódico com pole pieces e 5 (cinco) ímãs permanentes, capaz de fornecer um campo magnético, no centro da estrutura, de 0,42 T. Neste caso, a geometria do arranjo periódico obtida é: raio interno rm1 e externo rm2 do ímã permanente são iguais a 3,5 mm e 7,5 mm respectivamente; raio externo do pole piece r3 = 7,5 mm ; raio interno rf1 e externo rf2 da ponteira do pole piece são 1,6 mm e 3,05 mm respectivamente; espessura do ímã permanente T=2,95 mm; período magnético L =8,5 mm. A remanência do ímã permanente utilizada é de Br=0,85 T. A malha dessa estrutura periódica magnética apresenta pouco mais de 20.000 nós e 40.000 elementos. / In this paper we analyze the problem of transport of the electron beam in electron guns, periodic arrays of permanent magnets and collectors of simple and multiple stages. This analysis is of relevance in the design of power microwave devices such as klystron amplier and TWT valve. The dynamics of particles is determined from the solution of the equation of the trajectory that is derived from the Lorentz force and energy conservation law. The equation of the trajectory obtained is differential of second-order, non-linear and time independent for the generalized potential. It is used the Runge-Kutta 4th order method to integrate the equation of the trajectory of the particles. The electric scalar potential is obtained from the solution of the Poisson equation. Numerically, we obtain the electric and magnetic scalar potentials, using the Finite Element Method (FEM). Throughout the motion of a particle, obtained from the solution of the equation of the trajectory, electrical charge it is deposited. Macroparticles are used, since it is virtually impossible to model each particle of the problem, based on Particle in Cell scheme (Particle in Cell - PIC). In this case, there is a coupled problem for the electric scalar potential and the trajectories of the macroparticles, since these trajectories depend on the potential and the potential, in turn, depends on the trajectories. In order to abtain the convergence of this coupled problem, it used the Method of Successive Approximations (MSA). The platform developed, based on the above methods, consists of two computational tools. The rst, XMGUN, is dedicated to the project of: electron guns with grids and shadow-grids, and collectors of simple and multiple stages, where secondary electrons emission is considered. The second, XMAGUN, is used to the design of periodic permanent magnets structures. The XMGUN was benchmarked against the plan Pierce diode under space charge limited condiction. In turn, the XMAGUN was benchmarked against PPM like structures, separated by a vacuum and in the presence of pole pieces. The results, in all simulations, converged satisfactorily to the analytical solu- tions. Using XMGUN, it is designed an electron gun with 30 kV anode voltage, 1.37 Perv capable of supplying an electric current of 7.1 A. This gun has a mesh with 2796 elements and 5057 nodes. The main geometric characteristics of the electron gun are: cathode radius rc = 14.6 mm; cathode disc radius rk = 6.2 mm; and half cone angle = 37. In this case, the normalized transverse velocity and beam-waist distance from anode zw are 0.068 and 26.88 mm respectively. An agreement above 93% in current and perveance is found when compared with EGUN. XMGUN is also used to simulate single and multi stage collectors. The single-stage collector has 1612 nodes and 2969 elements, while the 4 (four) stages collector has 2496 nodes and 4257 we elements. The collector electrode voltages of the 1st, 2nd, 3rd and 4th stage are 9.45 kV 8.65 kV 3.45 kV 6.45 kV, respectively. During the simulations, due to yield of secondary electrons, for the single stage collector, it is observed macroparticles entering into the drift region, a phenomenon unwanted, and not observed for the 4 (four) stage collector. Whereas XMAGUN is projected at a periodic arrangement with pole pieces and 5 (ve) permanent magnets, capable of providing a magnetic eld in the center of the structure was 0.42 T. In this case, the geometry of the periodic arrangement is obtained: inner and outer radius of the permanent magnet rm1 = 3.5 mm and 7.5 mm respectively rm2 =; outer radius of the pole piece r3 = 7.5 mm, internal radius and external tip of the pole piece rf1=rf2 =1.6 mm and 3.05 mm respectively; permanent magnet thickness T = 2.95 mm magnetic period L = 8.5 mm. The remanence of the permanent magnet used is Br = 0.85 T. The net periodic structure of magnetic features little more than 20,000 nodes and 40,000 elements.

Main goal of diploma work "Feasibility Study of Shooting Range for Tactical Shooting and Gun and Ammunition Store" was discovered, if the project is realizable and in which conditions. Used methodology is text analysis mostly of laws, but also expert texts and publications. Next used methodology is collecting and evaluation of information, which relate with establishment and operation of a shooting range and gun shop, also with creation of a financial plan from different sources. The work closely engage in necessary factors for successful establishment of a shooting range and gun shop, feasibility study, investment and operational costs, incomes, balance sheet, profit and loss statement, basic financial indicators and cash flow. End of the work contains report of feasibility which is summarized benefits and threats of the project.

Neste trabalho analisa-se o problema do transporte do feixe de elétrons em canhões de elétrons, estruturas periódicas de ímãs permanentes e em coletores de simples e múltiplos estágios. Essa análise é de relevância em projetos de dispositivos de micro-ondas de potência dos tipos amplicador klystron e válvula TWT. Determina-se a dinâmica das partículas a partir da solução da equação da trajetória que é derivada da força de Lorentz e da conservação de energia. A equação da trajetória obtida é diferencial de segunda ordem, não-linear e independentemente do tempo para o potencial generalizado. Utiliza-se o método de Runge-Kutta de 4a Ordem para integrar a equação da trajetória das partículas. Obtém-se o potencial escalar elétrico a partir da solução da equação de Poisson. Numericamente, obtêm-se os po- tenciais escalares elétricos e magnéticos, por meio do Método de Elementos Finitos (MEF). Ao longo do movimento de uma partícula, obtida a partir da solução da equação da trajetória, deposita-se carga elétrica. Utilizam-se macropartículas, uma vez que é praticamente impossível modelar cada partícula do problema, a partir do método Partícula na Célula (Particle in Cell - PIC). Neste caso, tem-se um problema acoplado para o potencial escalar elétrico e as trajetórias das macropartículas, uma vez que, as trajetórias das macropartículas dependem dos potenciais e estes, por sua vez, dependem das trajetórias. À convergência deste problema acoplado utiliza-se o Método das Aproximações Sucessivas (MAS). A plataforma desenvolvida, baseada nos métodos acima, compõe-se de duas ferramentas computacionais. A primeira, XMGUN, dedica-se ao projeto de: canhões de elétrons com grades e grades de sombreamento; e coletores de simples e múltiplos estágios considerando, ainda, a emissão de elétrons secundários. A segunda, XMAGUN, volta-se ao projeto de estruturas periódicas com ímãs permanentes. Afere-se o desempenho da ferramenta computacional XMGUN com o diodo plano de Pierce operando na condição em que a corrente é limitada pelas cargas espaciais. Por sua vez, verica-se o desempenho do XMAGUN por meio de simulações com estruturas do tipo PPM separadas pelo vácuo e na presença de pole pieces. Os resultados obtidos em todas as simulações convergiram satisfatoriamente para as soluções analíticas. Utilizando o XMGUN, projeta-se um canhão de elétrons com 30 kV de tensão de anodo e uma perveância de 1,37 Perv com capacidade de fornecer uma corrente elétrica de 7,1 A. Esse canhão tem uma malha com 2796 elementos e 5057 nós. As principais características geométricas do canhão de elétrons são: raio do catodo rc=14,6 mm; raio do disco do catodo rk =6,2 mm; e ângulo do eletrodo de focalização = 37. Neste caso, a velocidade transversal normalizada e o alcance do feixe zw observados são de 0,068 e 26,88 mm respectivamente. Obtém-se uma concordância superior a 93% em corrente e perveância com o EGUN. Utilizando, ainda, o XMGUN, são simulados coletores de simples e múltiplos estágios. O coletor de simples estágio apresenta 1612 nós e 2969 elementos, e o de 4 (quatro) estágios, 2496 nós e 4257 elementos. As tensões dos eletrodos do 1o, 2o, 3o e 4o estágio são de 9,45 kV, 8,65 kV, 6,45 kV e 3,45 kV respectivamente. Durante as simulações, devido à emissão de elétrons secundários, observa-se, para o coletor de simples estágio, macropartículas penetrando na região de deriva, fenômeno este indesejado, e não observado para o coletor de 4 (quatro) estágios. Considerando o XMAGUN, projeta-se um arranjo periódico com pole pieces e 5 (cinco) ímãs permanentes, capaz de fornecer um campo magnético, no centro da estrutura, de 0,42 T. Neste caso, a geometria do arranjo periódico obtida é: raio interno rm1 e externo rm2 do ímã permanente são iguais a 3,5 mm e 7,5 mm respectivamente; raio externo do pole piece r3 = 7,5 mm ; raio interno rf1 e externo rf2 da ponteira do pole piece são 1,6 mm e 3,05 mm respectivamente; espessura do ímã permanente T=2,95 mm; período magnético L =8,5 mm. A remanência do ímã permanente utilizada é de Br=0,85 T. A malha dessa estrutura periódica magnética apresenta pouco mais de 20.000 nós e 40.000 elementos. / In this paper we analyze the problem of transport of the electron beam in electron guns, periodic arrays of permanent magnets and collectors of simple and multiple stages. This analysis is of relevance in the design of power microwave devices such as klystron amplier and TWT valve. The dynamics of particles is determined from the solution of the equation of the trajectory that is derived from the Lorentz force and energy conservation law. The equation of the trajectory obtained is differential of second-order, non-linear and time independent for the generalized potential. It is used the Runge-Kutta 4th order method to integrate the equation of the trajectory of the particles. The electric scalar potential is obtained from the solution of the Poisson equation. Numerically, we obtain the electric and magnetic scalar potentials, using the Finite Element Method (FEM). Throughout the motion of a particle, obtained from the solution of the equation of the trajectory, electrical charge it is deposited. Macroparticles are used, since it is virtually impossible to model each particle of the problem, based on Particle in Cell scheme (Particle in Cell - PIC). In this case, there is a coupled problem for the electric scalar potential and the trajectories of the macroparticles, since these trajectories depend on the potential and the potential, in turn, depends on the trajectories. In order to abtain the convergence of this coupled problem, it used the Method of Successive Approximations (MSA). The platform developed, based on the above methods, consists of two computational tools. The rst, XMGUN, is dedicated to the project of: electron guns with grids and shadow-grids, and collectors of simple and multiple stages, where secondary electrons emission is considered. The second, XMAGUN, is used to the design of periodic permanent magnets structures. The XMGUN was benchmarked against the plan Pierce diode under space charge limited condiction. In turn, the XMAGUN was benchmarked against PPM like structures, separated by a vacuum and in the presence of pole pieces. The results, in all simulations, converged satisfactorily to the analytical solu- tions. Using XMGUN, it is designed an electron gun with 30 kV anode voltage, 1.37 Perv capable of supplying an electric current of 7.1 A. This gun has a mesh with 2796 elements and 5057 nodes. The main geometric characteristics of the electron gun are: cathode radius rc = 14.6 mm; cathode disc radius rk = 6.2 mm; and half cone angle = 37. In this case, the normalized transverse velocity and beam-waist distance from anode zw are 0.068 and 26.88 mm respectively. An agreement above 93% in current and perveance is found when compared with EGUN. XMGUN is also used to simulate single and multi stage collectors. The single-stage collector has 1612 nodes and 2969 elements, while the 4 (four) stages collector has 2496 nodes and 4257 we elements. The collector electrode voltages of the 1st, 2nd, 3rd and 4th stage are 9.45 kV 8.65 kV 3.45 kV 6.45 kV, respectively. During the simulations, due to yield of secondary electrons, for the single stage collector, it is observed macroparticles entering into the drift region, a phenomenon unwanted, and not observed for the 4 (four) stage collector. Whereas XMAGUN is projected at a periodic arrangement with pole pieces and 5 (ve) permanent magnets, capable of providing a magnetic eld in the center of the structure was 0.42 T. In this case, the geometry of the periodic arrangement is obtained: inner and outer radius of the permanent magnet rm1 = 3.5 mm and 7.5 mm respectively rm2 =; outer radius of the pole piece r3 = 7.5 mm, internal radius and external tip of the pole piece rf1=rf2 =1.6 mm and 3.05 mm respectively; permanent magnet thickness T = 2.95 mm magnetic period L = 8.5 mm. The remanence of the permanent magnet used is Br = 0.85 T. The net periodic structure of magnetic features little more than 20,000 nodes and 40,000 elements.

This research sought to explore media framing theory, first introduced by Erving Goffman, which asserts that the media portray certain items in a way that affects awareness, salience and tone of those items. There has long been debate about media framing especially as it pertains to the framing of violent events. Mass shootings are of particular interest because of the graphic and often senseless nature of the crime. This study looked particularly at the 2011 Tucson, Arizona mass shooting. A content analysis of articles between February 7, 2010, and November 8, 2011, was conducted to explore media framing of gun control after the Tucson, Arizona mass shooting involving U. S. Representative Gabrielle Giffords. Results showed an equal amount of articles with a negative or neutral tone, with the tone shifting to being more frequently neutral after the shooting. The topic shifted toward legislation, adding further support to media framing theory. These findings have impacts for media and public relations.

The purpose of this qualitative ethnographic study was to explore citizen perceptions of the phenomenon of law enforcement shootings involving an imitation firearm. A secondary purpose was to document knowledge of current imitation firearm policies and thoughts on the effectiveness of said policies. Kingdon's multiple streams approach was used as the theoretical framework. This theory addressed the sources of power that influence policy decisions, the stakeholders involved in agenda setting, and factors that shape policy debates. Data were collected using a combination of secondary data analysis, field observations and semi structured, face-to-face interviews with 23 citizens. Sampling strategies included a combination of snowball, purposeful, and variation sampling to identify interviewees from four specific subject groups: law enforcement, parents of children aged 10-17-years-old, citizens with no law enforcement experience and no children aged 10-17-years-old, and leaders in the community. Results from domain and taxonomic coding revealed the themes of safety, responsibility, and accountability. Specifically, subjects wanted to ensure both law enforcement and citizens were safe in the community, they wanted to see parents take responsibility for their children, and they wanted to see legislation that held people accountable for their actions when using imitation firearms during the commission of a crime. Findings may be used for positive social change by enhancing imitation firearm policies, recognizing ways to improve data tracking, and identifying educational opportunities for both citizens and law enforcement. Enhanced firearm policies can also help mitigate unnecessary shootings and reduce community conflicts between citizens and police.

Today, the strength of the National Rifle Association (NRA) is understood by the general public and many scholars to be dependent on the Second Amendment of the U.S. Constitution, the right of individuals to own firearms. This dissertation challenges that understanding by focusing on three organizations, the NRA, the National Guard and the National Board for the Promotion of Rifle Practice (NBPRP). While each organization appears in today's world to be distinct and independent, this dissertation reveals how they garnered strength from a symbiotic relationship. The NRA was founded in 1871, originally as a marksmanship organization. The National Guard, which grew from the nation's militia, was formally established in the early twentieth century. The NBPRP was a small organization that was established in 1903 within the War Department at the encouragement of the NRA. Following passage in 1903 of legislation bringing state militia units under federal control, the newly formed National Guard became dependent on the NRA, which in turn leveraged that dependence to create a nationwide grassroots organization. The NBPRP was headed by the Assistant Secretary of War until 1916 when the position of the Director of Civilian Marksmanship was created, to be held by a U.S. Army or U.S. Marine Corps officer. The NRA acted as the surrogate of the NBPRB outside of the halls of government. At the same time, the NBRPB provided the NRA with a voice within those same halls that aided in the development of federal policy and budget positions related to firearms acquisition, competition, and training. The purpose of this dissertation is to reveal how the NRA was able to employ these two organizations to develop an exceptionally powerful grassroots organization that today is recognized as one of the most powerful special interest groups in America. Understanding how this powerful organization grew offers one perspective of how the bureaucracy that has been developed to support America's federal system of government is uniquely susceptible to special interest influence.