Head and facial injuries constitute a substantial portion of bicyclist injuries. Helmets reduce bicyclists' head and facial injuries, but not to the same extent for all injury types and locations. Current safety standards for bicycle helmets around the world, including EN1078 (Europe), CPSC 16 CFR 1203 (United States), JIS T8134 (Japan), AS/NZS 2063 (Australia and New Zealand) and GB 24429 (China), prescribe a standard test line or area for impact attenuation assessment that has limited coverage to head and face. The middle and lower part of the face, which are not protected by most existing helmet designs, are susceptible to soft tissue injuries, fractures and mandibular loading that can cause diffuse brain injury and basilar skull fracture. This study aims to quantify bicyclist head impact locations based on the Germ.an In-Depth Accident Study (GIDAS). Knowing which part of the head is impacted most frequently can inform future test method development and helmet designs beyond existing standards requirement. [from Introduction]

The aim of this research was to produce a reliable finite element model of a helmet, that could be used to simulate approval tests as well as impacts to investigate the safety offered. A 2D and 3D mesh was generated from the CAD file of an Easton Synergy 380 with HyperWorks, and then checked referring to standard parameter values. A few specimens cut from the liner were tested with the Instron Electropuls E3000 (Instron, High Wycombe, Great Britain) machine to determine Young’s modulus, Poisson’s ratio and the density of the EPP. The numerical model was characterised with appropriate materials with Ls-PrePost, such as ABS for the shell, EPP for the liner and steel for the impact anvil. The foam was implemented both with the *063_CRUSHABLE_FOAM and the *126_MODIFIED_HONEYCOMB card, in two different configurations. The helmet model was coupled with a finite element model of a HIII head form and three impact scenarios were set up. Backward, lateral and pitched impact were simulated and results were compared with those obtained from the experimental tests carried on at the MIPS. The two configurations were tested in all the three scenarios. The correlation between numerical and experimental results was evaluated by analysing the linear and rotational acceleration, and the rotational velocity, recorded by the accelerometer positioned inside the HIII headform. The parameters used were the Pearson correlation coefficient, the peak linear acceleration score, the shape of the curves, the time occurrence of peaks and the percentage of the difference between them. The first configuration showed good correlation scores (>85%) for the backward and lateral impact, for the rotational velocity and acceleration, while lower values were recorded for the pitched impact simulation. Lower values (70.88% and 77.76%) were obtained for the peak linear acceleration score, which stress the need for modifications of the contact definition in Ls-PrePost or a more detailed material testing. Worse results were recorded for the second configuration, but the smaller computational time required suggests that more attempts should be done in this direction.

Background: Every country has seen an increase in motorcycle accidents over the years due to social and economic differences as well as regional variations in transportation circumstances. One common mode of transportation for those in the middle class is a motorbike.  Every motorbike rider is legally required to wear a helmet when driving a bike. However, some people on bikes used to ignore their safety, which resulted in them violating traffic rules by driving the bike without a helmet. The policeman tried to address this issue manually, but it was ineffective and proved to be quite challenging in practical circumstances. Therefore, automating this procedure is essential if we are to effectively enforce road safety. As a result, an automated system was created employing a variety of techniques, including Convolutional Neural Networks (CNN), the Haar Cascade Classifier, the You Only Look Once (YOLO), the Single Shot multi-box Detector (SSD), etc. In this study, YOLOv3 and Haar Cascade Classifier are used to compare motorcycle helmet and license plate detection.  Objectives: This thesis aims to compare the machine learning algorithms that detect motorcycles’ license plates and helmets. Here, the Haar Cascade Classifier and YOLO algorithms are used on the US License Plates and Helmet Detection datasets to train the models. The accuracy is obtained in detecting the helmets and license plates of the motorcycles and analyzed.  Methods: The experiment method is chosen to answer the research question. An experiment is performed to find the accuracy of the models in detecting the helmets and license plates of motorcycles. The datasets utilized for this are from Kaggle, which included 764 pictures of two distinct classes, i.e., with and without a helmet, along with 447 unique license plate images. Before training the model, preprocessing techniques are performed on US License Plates and Helmet Detection datasets. Now the datasets are divided into test and train datasets where the test data set size is considered to be 20% and the train data set size is 80%. The models are trained using 80% pre-processed training datasets and using the Haar Cascade Classifier and YOLOv3 algorithms. An observation is made by giving the 20% test data to the trained models. Finally, the prediction results of these two models are recorded and the accuracy is measured by generating a confusion matrix.   Results: The efficient and best algorithm for detecting the helmets and license plates of motorcycles is identified from the experiment method. The YOLOv3 algorithm is considered more accurate in detecting motorcycles' helmets and license plates based on the results.  Conclusions: Models are trained using Haar Cascade and YOLOv3 algorithms on US License Plates and Helmet Detection training datasets. The accuracy of the models in detecting the helmets and license plates of motorcycles is checked by using the testing datasets. The model trained using the YOLOv3 algorithm has high accuracy; hence, the Neural network-based YOLOv3 technique is thought to be the best and most efficient.

Huvudskador inom alpin skidsport är bland de allvarligaste skador som kroppen utsätts för. Tidigare studier på huvudskador som genomförts på grenar såsom Störtlopp, Super-G, Storslalom, Skicross, Freestyle och Snowboard visar att standarder som finns på skyddsutrustning inte är tillräckliga. Ännu har ingen videoanalys genomförts på disciplinen Slalom med fokus på huvudets islag med underlaget under olyckor trots att dylika händelser har rapporterats. Certifieringar av hjälmar inom dessa discipliner skiljer sig och har genom åren påverkats av studier och forskning. Detta har resulterat i regeländringar och ökade krav på säkerhetsstandarder satta av Internationella Skidförbundet (FIS). Videoanalyser av olyckstillfällen inom snösport omfattar en hel del antaganden vilket medför problematik för okända variabler då de sker genom rekonstruktioner. De variabler som är kända utnyttjas för att uppskatta dessa okända värden. Denna avhandling syftade till att rekonstruera olyckor i slalomdisciplinen för att undersöka vilka hastigheter som faktiskt uppstår vid huvudkollison mot underlaget, samt därefter utröna eventuella samband mellan utövarens färdhastighet och underlagets lutning. Detta för att möjligen påverka eller upplysa om de faktiska hastigheter som uppstår för att validera de standardiserade certifieringar som idag är stadgade. Resultatet av den här studien visar tendenser på att en minskad lutning på underlaget ger en högre islagshastighet för huvudet mot underlaget. Färdhastigheten enskilt påverkar inte i lika stor uträckning som lutningen men bidrar till att öka islagshastigheten. I ett av de åtta analyserade fallen uppmättes 5,94 m/s, vilket överskred de testkrav för hjälmar satta till 5,42 m/s enligt EN-1007:2007 Klass B skyddscertifiering. / Head injuries in alpine skiing are the most serious injuries exposed to the human body. Previous studies applied to Downhill, Super-G, Giant Slalom, Skicross, Freestyle and Snowboard shows that safety standards on protection equipment may not be enough. In the slalom discipline no such video analysis studies have yet been deployed on head impacts in the Slalom discipline, although several incidents have been reported. Certifications for helmets in the respective disciplines differ and each of them have become influenced by studies and research throughout the years. This has resulted in rule changes and increased standards set by the International Ski Federation (FIS). Video analysis of athletes in snow sports causes problems with unknown variables based on rough reconstruction of past events, which lead to assumptions. To estimate these unknown values known variables play a critical role. This thesis aimed to reconstruct accidents in the slalom discipline to investigate the velocities for head collisions normal to the ground. Hence evaluate the relationship between the athlete’s travel speeds and the slope angle. This is to influence or inform about the speeds that arise to validate the standardized certifications that are currently stipulated. The result of this study shows tendencies that head collisions on lower slope angle results in a higher impact velocity. The travel speed alone does not affect to the same extent as the slope angle, but in combination the effect is to a greater degree. In one of the eight cases the impact velocity exceeded 5,42 m/s for the absorptions test according to EN-1007:2007 Class B certification, the highest measured value was 5,94 m/s. / <p>Betygsdatum 2023-06-07</p>

No description available.

A study of moisture management in helmet padding compositions. Paddings popularly consist of a polyurethane foam in combination with an inner fabric worn next to skin. The materials consisted of one polyurethane foam and four different fabrics. Tests of moisture management and related properties were performed. The polyurethane foam showed no signs of moisture transport abilities. Among the fabrics, the more porous, mesh-like ones performed the best. The polyurethane foam did not show to have any significant influence on the moisture management of the fabrics.

Nearly 3.5 million kids play youth football every year in the United States, many in independent organizations with few or no rules for limiting head impact exposure in practices or competition. Studies have found potential long-term effects of repetitive head impact exposure from a young age, even in the absence of concussion. The best methods for reducing head impact exposure include a multi-pronged approach: limiting contact through rules changes, teaching proper technique for contact when it does occur, and designing equipment with better protective capabilities. Four youth football teams were studied for one season each using helmet mounted accelerometer arrays. Head acceleration data indicated that youth teams often have a small subset of players who account for a disproportionately large number of high-risk head impacts. As few as six players (6%) accounted for over 50% of all high-risk impacts seen in practice sessions. Technique used during tackling and tackle-absorption had considerable effect on head acceleration. Both the tackler and ball carrier were found to be at greater risk for high magnitude head impacts when exhibiting poor form as defined by specific tackling recommendation criteria. These data suggest that individualized interventions encouraging proper form, especially for a subset of impact-prone players, may be beneficial in reducing high magnitude head impact exposure for an entire youth football team. This is especially critical because a majority of high-risk impacts are experienced in practice at the youth level. Results from this work could be applied by coaching staffs in youth football leagues to increase the safety of their athletes. / MS / Nearly 3.5 million kids play youth football every year in the United States, many in independent organizations with few or no rules for limiting head impact exposure in practices or competition. Studies have found potential long-term effects of repetitive head impact exposure from a young age, even in the absence of concussion. The best methods for reducing head impact exposure include a multi-pronged approach: limiting contact through rules changes, teaching proper technique for contact when it does occur, and designing equipment with better protective capabilities. Four youth football teams were studied for one season each using helmet mounted accelerometer arrays. Head acceleration data indicated that youth teams often have a small subset of players who account for a disproportionately large number of high-risk head impacts. As few as six players (6%) accounted for over 50% of all high-risk impacts seen in practice sessions. Technique used during tackling and tackle-absorption had considerable effect on head acceleration. Both the tackler and ball carrier were found to be at greater risk for high magnitude head impacts when exhibiting poor form as defined by specific tackling recommendation criteria. These data suggest that individualized interventions encouraging proper form, especially for a subset of impact-prone players, may be beneficial in reducing high magnitude head impact exposure for an entire youth football team. This is especially critical because a majority of high-risk impacts are experienced in practice at the youth level. Results from this work could be applied by coaching staffs in youth football leagues to increase the safety of their athletes.

Ce travail de recherche porte sur la compréhension du traumatisme crânien (TC) dans les sports de glisse alpins dans l’objectif d’améliorer et d’encadrer la conception et l’évaluation des casques de ski. Il s’est décomposé en quatre étapes :Etudier les accidents de ski conduisant au TC en identifiant des typologies d’accidents de ski et de snowboard conduisant fréquemment à l’apparition de TC. A partir d’un questionnaire rempli dans 10 cabinets médicaux et 3 hôpitaux, dix scénarios d’accident ont été identifiés ainsi que les zones de la tête les plus impactées. Cette analyse est complétée par des mesures de vitesse des skieurs.Identifier les conditions d’impact de la tête en reproduisant numériquement la cinématique de ces accidents avec un modèle multicorps de skieur. Deux types d’impact ressortent de cette analyse: les impacts sur neige, majoritaires (70%) et plutôt de faibles gravités et les impacts lors de collisions, plus rares, mais souvent plus graves.Évaluer la capacité des casques à réduire le TC en combinant approches expérimentales (impact de tête instrumentée sur neige) et simulations par éléments finis (reproduction d’impacts réalistes avec un modèle d’humain virtuel). Le casque réduit efficacement le risque de TC grave lors d’impact contre un obstacle rigide, mais son efficacité reste limitée lors d’impacts contre de la neige.Explorer des pistes d’amélioration du casque. Trois solutions ont été proposées, évaluées expérimentalement et numériquement et optimisées au regard des deux impacts cibles « neige » et « obstacle ». Le prototype proposé réduit de 30% les niveaux d’accélération de la tête lors de ces impacts par rapport aux casques traditionnels. / The aim of the project was to better understand traumatic brain injury (TBI) in alpine sports in order to improve the design and the evaluation of helmets. The work was divided in four main steps: Study skiing and snowboarding accidents leading to TBI: Ten scenarios were identified with a survey available in 10 medical centers and in 3 hospitals. The frontal and occipital zones were the most impacted parts of the head. Speed measurements were performed on ski slopes to complete the accident conditions analysis.Identify head impact conditions during these accidents: We reproduced the kinematics of these accidents using a numerical model of skier and snowboarder (multibody model). We identified two types of impact: impacts against the snow are the most frequent (70%) and are associated with mild TBI whereas impacts during collision are less frequent but are more likely to induce severe TBI. Evaluate helmet effectiveness in reducing the TBI combining experimental approach (Impacts of an instrumented head against the snow) and finite element simulations (Realistic head impacts reproduced numerically using a human model). Helmets were good at reducing the risk of severe TBI during an impact against a rigid obstacle. However the effectiveness of the helmets at reducing injury risk during an impact against the snow was limited. Improve helmet design: Three solutions were studied. These solutions were proposed, evaluated experimentally and numerically and optimized regarding the two targeted impacts “snow” and “obstacle”. The prototype of the optimized helmet reduces by 30% the acceleration of the head during these impacts compared to traditional helmets.

The requirement to operate vehicles in low light and/or night environments whilst wearing night vision goggle (NVG) systems has become increasingly common during military operations. There is very limited research investigating injury risks associated with these systems during ground vehicle collisions. This study examined the injury risks associated with wearing the Australian Defence Force - Enhanced Combat Helmet (ECH) and NVG system, in frontal vehicle collisions. This project consisted of two components: (1) crash tests using a sled and (2) numerical simulations of impacts. Four dynamic sled tests were conducted using a 50th percentile, male, Hybrid III dummy positioned on a rigid seat. Frontal impact tests were performed at a 40 km/h change in velocity (*v) and 20 g deceleration. The test configurations were as follows: (a) Base; (no helmet or additional equipment); (b) ECH; and, (c) ECH and NVG. Condition (c) was carried out twice, to determine repeatability. The sled test protocols were reconstructed precisely with the numerical simulation package MADYMO and the simulations were shown to correlate well with the experimental results. Using this validated model, four parametric studies were undertaken to assess the influence of counterweights, seat cushion, seatbelt pre-tensioner, and the vehicle's *v and acceleration on injury risks. The study found that neck loads were within acceptable limits, with the exception of the neck extension moment, which was exceeded for all NVG conditions. Based on the parametric studies, no major improvements were observed in the neck extension moments with the use of counterweights or a seat cushion. In contrast the use of a seatbelt pre-tensioner was observed to decrease greatly this neck injury risk in certain scenarios. The study also identified that a *v of 15 km/h and peak acceleration of up to 14 g were required to keep the neck extension moment below the prescribed injury criteria. However, the high neck extension moment values may have been partially attributable to the stiff Hybrid III neck. This study identified a possible injury mechanism for soldiers using the ECH and NVG system during specific impact scenarios. The method applied in this project was designed to be repeatable.

This thesis reports on a design study, conducted for an advanced composite helmet shell for helicopter pilots. The helmet shell is expected to provide a level of protection against low velocity impacts with its weight criteria. Therefore, ergonomy, light weight, and the ability to withstand low velocity impact became the main issues for this study. For this purpose, an experimental program has been developed including low velocity impact tests on specimens. The drop height, drop weight, specimen stacking sequences and size were constant parameters. Test specimens were produced using the plate size of 220x220 mm having different thicknesses. Specimen materials were aramid, carbon, and a hybrid form of these two. Thus, the parameters of the study were specimen thickness and the material types. The impact tests are carried out on a specially designed test rig. The design decisions are made in accordance with the results of the experiments. In compliance with the lightweight and manufacturing criteria, the hybrid specimen was selected helmet shell. For the purpose of ergonomy a geometric design was also conducted from headfrom sizes of Turkish Army by using 3D design software. After specifying the composite material, manufactured helmet shell was tested in another test rig according to the ANSI Z90.1.1992. For the requirement of the acceleration level 300g, the helmet shell design was found to be successful at seven different and critical impact points.