Image matching of firearm fingerprints

A spent cartridge case exhibits characteristic markings (firearm fingerprint) that can be used to identify the type and possibly make of weapon in which the cartridge was fired. This report details research into the use of discriminant analysis for the purpose of matching spent rim-fire cartridge cases to specific make and model firearms. The discrimination and classification are based on several scalar shape parameters for the two-dimensional silhouette of the firing pin (FP) impression-- shape factor calculated from the second order moment of inertia, G factor calculated from the distance transform, and the P2A factor- as well as the distance between the centre of the cartridge case and the centroid of the FP impression, and the orientation of the principal centroidal axes associated with the FP impression. Classification results for two case studies are detailed: (i) 3 different make/model weapons producing different shaped FP impressions, and (ii) 5 different make/model weapons each producing a rectangular FP impression

The influence of firearms and ammunition properties on the effectiveneses of automated ballistic correlations

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2020.Esta pesquisa investiga propriedades físicas, mecânicas e geométricas de armas de fogo e munições, para determinar quais são os fatores que mais influênciam a eficácia de correlações balísticas automatizadas, que são realizadas por sistemas que correlacionam deformações plásticas impressas nos componentes de munição durante o processo de disparo. Para possibilitar este estudo 1684 componentes de munição, disparados com diferentes tipos de munição de revólveres .38SPL, e pistolas 9x19mm e .40S&W, foram digitalizados nos sistemas de identificação balística Arsenal® , Evofinder® , e IBIS® . Um critério de eficácia, baseado na acurácia das listas de resultado disponibilizadas pelos sistemas, foi utilizado para medir o grau de influência de parâmetros das armas e das munições na eficácia das correlações automatizadas. Um decaimento exponencial foi encontrado para a eficácia como função do tamanho do banco de dados em diversos calibres e sistemas. Devido aos valores e características do decaimento observado a influência do crescimento do banco de dados mostrou-se menos crítica do que anteriormente considerada. Análise de variança (ANOVA) suporta influência significativa da dureza dos projéteis, uma maior diferença na dureza entre os projéteis comparados resultando em 0.16, 0.18 e 0.13 menor eficácia nos sistemas Arsenal®, Evofinder®, e IBIS®. Composição e tipo de projétil, tipo de cano, fabricante da arma, calibre, número de padrões cadastrados, e tipos de correlações realizadas em cada sistema foram fatores adicionais com influência relevante na eficácia das correlações com projéteis. ANOVA revelou variação estatisticamente significativa também da energia de disparo nas correlações de estojos por marca de culatra, resultando em média 0.04, 0.006, e 0.09 decréscimo na eficácia de cada sistemas. Já por pino percutor, não houve evidência contra a hipótese nula, com exceção do sistema IBIS®, com variação de 0.12 na eficácia em função da energia de disparo. Adicionalmente, uma relação entre a velocidade do projétil, e consequentemente da energia de disparo, foi estabelecida com a massa e composição do propelente, a massa do projétil, o tipo e comprimento do cano, e o arrasto ao que o projétil é submetido dentro do cano. Outros fatores com influência relevante na correlação com estojos foram o tipo de estojo, calibre, número de padrões cadastrados, tipos de correlações realizadas, profundidade da marca de percussão, e presença da marca de bigorna. Uma comparação de eficácia pelo fabricante da arma revelou que a unicidade e reprodutibilidade das marcas geradas não são os únicos fatores para uma correta correlação tanto com projéteis quanto com estojos, uma vez que se obteve diferenças de desempenho significativas entre os sistemas avaliados. Ou seja, os fatores que influenciam a deformação plástica afetarão a eficácia da correlação, mas as possibilidades de identificação correta também dependem da precisão e da capacidade dos algoritmos empregados. Os resultados permitiram a identificação de diferenças em desempenho e fatores de influência que podem ser utilizados para refinar os sistemas, bem como para o estabelecimento de protocolos de operação dos sistemas por calibre, visando desta forma aumentar a probabilidade de identificação da arma fonte.This research investigates the physical, mechanical and geometric properties of firearms and ammunition, to determine which are the factors that most influence the effectiveness of automated ballistic correlations, which are performed by systems that correlate plastic deformations printed on the ammunition components during firing. To enable this study, 1684 ammunition components, fired with different types of ammunition from .38SPL revolvers, and 9x19mm and .40S&W pistols, were digitized in the Arsenal®, Evofinder®, and IBIS® ballistic identification systems. An effectiveness criterion, based on the accuracy of the result lists made available by the systems, was used to measure the degree of influence of firearms and ammunition properties on the effectiveness of automated correlations. An exponential decay was found for effectiveness as a function of the database size in various calibers and systems. Due to the values and characteristics of the observed decay, the influence of the database growth proved to be less critical than previously considered. Variance analysis (ANOVA) supports significant influence of bullet hardness, a greater difference in hardness between the compared bullets resulting in 0.16, 0.18 and 0.13 decrement in the effectiveness of Arsenal®, Evofinder ®, and IBIS®. Bullet composition and type, barrel type, firearm manufacturer, caliber, number of registered test-fires, and types of correlations performed in each system were additional factors with a meaningful influence on the effectiveness of the bullet correlations. ANOVA also revealed a statistically significant impact of the discharge energy in the cartridge case correlations by breech face, resulting in average 0.04, 0.006, and 0.09 decrease in effectiveness of each system. For the firing pin correlations, there was no evidence against the null hypothesis, with the exception of the IBIS® system, with a variation of 0.12 in effectiveness as a function of the discharge energy. In addition, a relationship between the velocity of the bullet, and consequently the discharge energy, was established with the mass and composition of the propellant, the mass of the bullet, the type and length of the barrel, and the drag to which the bullet is subjected within the barrel. Other factors with a relevant influence on the cartridge case correlations were the type of cartridge case, caliber, number of registered test-fires, types of correlations performed, depth of the firing pin mark, and presence of the anvil mark. A comparison of effectiveness by the firearm manufacturer revealed that the uniqueness and reproducibility of the marks generated are not the only factor for a correct correlation with both bullet and cartridge cases, since significant performance differences were found between the systems assessed. That is, the factors that influence plastic deformation will affect the correlation effectiveness, but the possibilities of correct identification also depend on the accuracy and capabilities of the employed algorithms. The results allowed the identification of differences in performance and parameters of influence that can be used to refine the systems, as well as for the establishment of operation protocols of the systems by caliber, aiming in this way to increase the likelihood of identification of the source firear

Developing an acoustic sensing yarn for health surveillance in a military setting

Overexposure to high levels of noise can cause permanent hearing disorders, which have a significant adverse effect on the quality of life of those affected. Injury due to noise can affect people in a variety of careers including construction workers, factory workers, and members of the armed forces. By monitoring the noise exposure of workers, overexposure can be avoided and suitable protective equipment can be provided. This work focused on the creation of a noise dosimeter suitable for use by members of the armed forces, where a discrete dosimeter was integrated into a textile helmet cover. In this way the sensing elements could be incorporated very close to the ears, providing a highly representative indication of the sound level entering the body, and also creating a device that would not interfere with military activities. This was achieved by utilising commercial microelectromechanical system microphones integrated within the fibres of yarn to create an acoustic sensing yarn. The acoustic sensing yarns were fully characterised over a range of relevant sound levels and frequencies at each stage in the yarn production process. The yarns were ultimately integrated into a knitted helmet cover to create a functional acoustic sensing helmet cover prototype

Spartan Daily, September 11, 1975

Volume 65, Issue 3https://scholarworks.sjsu.edu/spartandaily/5991/thumbnail.jp

Usage pattern of personal stereo players and its potential effect on the hearing of teenagers in Hong Kong

A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, June 30, 2007.Thesis (B.Sc)--University of Hong Kong, 2007.Also available in print.published_or_final_versionSpeech and Hearing SciencesBachelorBachelor of Science in Speech and Hearing Science

Montana Kaimin, October 12, 1994

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/9789/thumbnail.jp