The design of equipment and thermal routines for annealing glass particles

Equipment for annealing casework sized glass particles is described. Investigations were carried out using a simple muffle furnace, a temperature programmed furnace and a metal sample holder. Because they produced a uniform and reproducible thermal environment, best results were obtained from a combination of the temperature programmed furnace and the metal sample holder. Refractive index changes for window and toughened glass specimens were investigated and a simple, reproducible annealing routine for casework was devised.     

The examination of glass particles using the interference objective. Part 2: A survey of flat and curved surfaces

The microscopical examination of original surfaces on casework sized glass particles using an interference objective and the interpretation of their interferograms is discussed. To reduce subjectivity, a numerical criterion was devised to assess the curvature of glass particles and this was then applied to a survey of window, container, tableware and vehicle glasses. Objects with curved surfaces produced particles that were distinctly curved while those from surfaces of both modern and old windows were clearly identifiable as flat. Apparently flat surfaces from tableware and containers almost always yielded specimens that were detectably curved. In addition, there was no evidence that a fracture surface would be confused with an original surface from a plain flat glass.In a ‘blind’ trial to assess the interferometric routines, three examiners correctly identified flat and curved surfaces on 15 particles derived from a selection of glass objects.     

An investigation into the relationship between edge counts and the variability of the refractive index of glass. Part I: Edge morphology

The effect of glass fragment morphology on the variability of refractive index values in five different glass objects was investigated. Data are presented that suggest that the variability of refractive index values is increased when fragment edge morphology becomes unsuitable for phase contrast microscopy.     

The statistical interpretation of refractive index measurements II: The multiple source problem

The method proposed by Grove [1] for comparing measurements made on control and recovered fragments is extended to deal with the possibility that the recovered fragments may originally have come from more than one source. The cases of two and four recovered fragments are examined in detail. Simulation results are given which show that the discriminatory power of the method varies with the number of sources and with the distribution of the fragments over those sources. It is greatest when the recovered fragments come from one source.     

诗意化之魅力悲剧——评《玻璃动物园》

《玻璃动物园》是一曲抒情、诗意的造型戏剧，再现19世纪30年代美国人生存状况。在该剧中，剧作家运用了多维艺术表现手法突出剧中人物的梦想之现实回味、悲剧之生存超越等悲剧主题，展示了该剧诗意化之艺术魅力，揭示了人类存在的意义：不断追求理想，为实现自己的理想而奋斗。     

Automatic Refractive Index Measurement of Glass particles

An automatic instrument for Glass Refractive Index Measurement (GRIM), developed by Foster and Freeman Ltd., has been evaluated and adapted to meet the requirements of the UK Forensic Science Service. The apparatus is microprocessor controlled and uses the signal from a CCTV camera to detect the match temperature of the glass. Prototypes were evaluated at the Metropolitan Police Forensic Science Laboratory, at the Central Research Establishment, Home Office Forensic Science Service and at the Home Office Forensic Science Laboratory, Aldermaston. The performance of GRIM was compared to that of the Mettler apparatus currently in use with special regard to precision and long-term stability. GRIM was found to be well suited for operational use.     

Bayesian mixture modelling for glass refractive index measurement

Glass is a common type of physical evidence in forensic science. Broken glass recovered from a suspect may have similar physical characteristics to glass collected at a crime scene and therefore can be used as evidence. Statistical treatment of this evidence involves computing a measure of the weight of evidence. This may be done in a Bayesian framework that incorporates information from the circumstances of the crime. One of the most crucial quantities in this calculation is the assessment of the relative rarity of the characteristics of the glass, essentially the probability distribution used to model the physical characteristics of recovered glass. Typical characteristics used in casework are the elemental composition of glass and the refractive index measurement. There is a considerable body of scientific literature devoted to the modelling of this information. For example a kernel density estimation has been used to model the background population of glass based on the refractive index measurement and a multivariate Gaussian finite mixture model has been used to model the elemental composition of glass. In this paper, we present an alternative approach, the Dirichlet Process Mixture Model, to model the glass refractive index measurement in a Bayesian methodology. A key advantage is that using this method allows us to model the probability density distribution of refractive index measurements in a more flexible way.     

动车玻璃破碎痕迹分析

动车运行过程中发生车窗玻璃破碎的情况具有突然性,对铁路运输安全有一定影响,并极易受到公众高度关注。动车玻璃破碎有的是人为因素引起,有的是非人为因素引起,判明玻璃破碎的原因,确定案事件性质,是采取有效措施,消除安全隐患的前提。笔者结合海南环岛高铁2010年以来发生的89起动车玻璃破碎案事件现场勘查实践以及广深线48起动车玻璃破碎案事件资料,对玻璃自爆、飞砟、弹弓弹射钢珠、抛石击打造成玻璃破碎的形成机制和痕迹特征进行了分析总结;针对抛石击打与飞砟形成玻璃破碎痕迹的区分难点,对两者因击打角度和方式不同、击打物的体积和质量的不同而形成痕迹的差异进行了深入探讨。