Relevant factors in the design of composite ballistic helmets

[EN] In this paper, the design methodology of composite ballistic helmets has been enhanced considering biomechanical requirements by means of finite element analysis. Modern combat helmets lead to a new type of non-penetrating injury, the Behind Helmet Blunt Trauma (BHBT), generated by the deformation of the inner face of the helmet, the so-called backface deformation (BFD). Current standard testing methodologies use BFD as the main measure in ballistic testing. Nonetheless, this work discusses the relationship between this mechanical parameter and the head trauma (BHBT) by studying different head injury criteria. A numerical model consisting of a helmet and a human head is developed and validated with experimental data from literature. The consequences of non-penetrating high-speed ballistic impacts upon the human head protected by an aramid combat helmet are analysed, concluding that the existing testing methodologies fail to predict many types of head injuries. The influence of other parameters like bullet velocity or head dimensions is analysed. Usually, a single-sized helmet shell is manufactured and the different sizes are adjusted by varying the foam pad thickness. However, one of the conclusions of this work is that pad thickness is critical to avoid BHBT and must be considered in the design process.The authors thank the financial support received from the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Regional Development Fund (ERDF-FEDER) through the project RTC-2015-3887-8, and from the Conselleria d'Educació, Investigació, Cultura i Esport of the Generalitat Valenciana through the program PROMETEO 2016/007.Palomar-Toledano, M.; Lozano-Mínguez, E.; Rodriguez-Millán, M.; Miguélez, MH.; Giner Maravilla, E. (2018). Relevant factors in the design of composite ballistic helmets. Composite Structures. 201:49-61. https://doi.org/10.1016/j.compstruct.2018.05.076S496120

Improving Online Interactions: Lessons from an Online Anatomy Course with a Laboratory for Undergraduate Students

An online section of a face-to-face (F2F) undergraduate (bachelor\u27s level) anatomy course with a prosection laboratory was offered in 2013-2014. Lectures for F2F students (353) were broadcast to online students (138) using Blackboard Collaborate (BBC) virtual classroom. Online laboratories were offered using BBC and three-dimensional (3D) anatomical computer models. This iteration of the course was modified from the previous year to improve online student-teacher and student-student interactions. Students were divided into laboratory groups that rotated through virtual breakout rooms, giving them the opportunity to interact with three instructors. The objectives were to assess student performance outcomes, perceptions of student-teacher and student-student interactions, methods of peer interaction, and helpfulness of the 3D computer models. Final grades were statistically identical between the online and F2F groups. There were strong, positive correlations between incoming grade average and final anatomy grade in both groups, suggesting prior academic performance, and not delivery format, predicts anatomy grades. Quantitative student perception surveys (273 F2F; 101 online) revealed that both groups agreed they were engaged by teachers, could interact socially with teachers and peers, and ask them questions in both the lecture and laboratory sessions, though agreement was significantly greater for the F2F students in most comparisons. The most common methods of peer communication were texting, Facebook, and meeting F2F. The perceived helpfulness of the 3D computer models improved from the previous year. While virtual breakout rooms can be used to adequately replace traditional prosection laboratories and improve interactions, they are not equivalent to F2F laboratories

Enabling Programmer-Controlled Combined Memory Consistency for Parallel Code Optimization

Approved for public release; distribution is unlimlted. _ P ublic reporting b&en for this coI!ecHon of lnform~tion k estlnuted to wvrege 1 hour per response, including the time for reviewing inskuctions, sesrrhing existing data sow, g&wring and minbhing the d&d neded and coq&thg and reviewing the collectIon Infbrmnlion. Send comment4 mgudlng this burden atimate or my ok aspea of this colktion of information