Search Results (11)

With the rapid development of the general aviation industry in China, the influence of high-impact aeronautical weather events, such as aircraft icing, on flight safety has become more and more prominent. On 1 March 2021, an aircraft conducting weather modification operations crashed over Ji’an City, due to severe icing. Using multi-source meteorological observations and atmospheric numerical simulations, we analyzed the meteorological causes of this icing accident. The results indicate that a cold front formed in northwestern China and then moved southward, which is the main weather system in the icing area. Based on the icing index, we conducted an analysis of the temperature, relative humidity, cloud liquid water path, effective particle radius, and vertical flow field, it was found that aircraft icing occurred behind the ground front, where warm-moist airflows rose along the front to result in a rapid increase of water vapor in 600–500 hPa. The increase of water vapor, in conjunction with low temperature, led to the formation of a cold stratiform cloud system. In this cloud system, there were a large number of large cloud droplets. In addition, the frontal inversion increased the atmospheric stability, allowing cloud droplets to accumulate in the low-temperature region and forming meteorological conditions conducive to icing. The Weather Research and Forecasting model was employed to provide a detailed description of the formation process of the atmospheric conditions conducive to icing, such as the uplifting motion along the front and supercooled water. Based on a real case, we investigated the formation process of icing-inducing meteorological conditions under the influence of a front in detail in this study and verified the capability of a numerical model to simulate the meteorological environment of frontal icing, in order to provide a valuable reference for meteorological early warnings and forecasts for general aviation. Full article

Frontal crash tests are an essential element in assessing vehicle safety. They simulate a collision that occurs when the front of the bus hits another vehicle or an obstacle. In recent years, much attention has been paid to the frontal crash testing of city buses, especially after a series of accidents resulting in deaths and injuries. Unlike car manufacturers, most bus bodybuilders do not include deformation zones in their designs. The next two regulations are widely used to assess whether a structure can withstand impact loading: UNECE Regulation No. 29—United Nations Economic Commission for Europe (UNECE R29) and the New Car Assessment Program (NCAP), which is more typical of car crash tests. The main goal of the research is to develop an applicable methodology for a frontal impact simulation on a city bus, considering UNECE R29 requirements for the passenger’s safety and distinctive features of the low-entry body layout. Among the contributions to current knowledge are such research results as: unlike suburban and intercity buses, city buses are characterized by lower stiffness in the event of a frontal collision, and therefore, when developing new models, it is necessary to lay deformation zones (currently absent from most city buses). Maximum deformation values in the bus front part are reached earlier for R29 (137 ms) than for most impacts tested by NCAP (170–230 ms) but have higher values: 577 mm vs. 150–250 mm for the sills tested. Such a short shock absorption time and high deformations indicate a significantly lighter front part of a low-entry and low-floor bus compared with classic layouts. Furthermore, it is unjustified to use the R29 boundary conditions of trucks to attach the bus with chains behind its frontal axe both in natural tests and appropriate finite element simulation—the scheme of fixing the city bus should be accordingly adapted and normatively revised. Full article

Individuals with obstructive sleep apnea (OSA) face increased accident risks due to excessive daytime sleepiness. PERCLOS, a recognized drowsiness detection method, encounters challenges from image quality, eyewear interference, and lighting variations, impacting its performance, and requiring validation through physiological signals. We propose visual-based scoring using adaptive thresholding for eye aspect ratio with OpenCV for face detection and Dlib for eye detection from video recordings. This technique identified 453 drowsiness (PERCLOS ≥ 0.3 || CLOSDUR ≥ 2 s) and 474 wakefulness episodes (PERCLOS < 0.3 and CLOSDUR < 2 s) among fifty OSA drivers in a 50 min driving simulation while wearing six-channel EEG electrodes. Applying discrete wavelet transform, we derived ten EEG features, correlated them with visual-based episodes using various criteria, and assessed the sensitivity of brain regions and individual EEG channels. Among these features, theta–alpha-ratio exhibited robust mapping (94.7%) with visual-based scoring, followed by delta–alpha-ratio (87.2%) and delta–theta-ratio (86.7%). Frontal area (86.4%) and channel F4 (75.4%) aligned most episodes with theta–alpha-ratio, while frontal, and occipital regions, particularly channels F4 and O2, displayed superior alignment across multiple features. Adding frontal or occipital channels could correlate all episodes with EEG patterns, reducing hardware needs. Our work could potentially enhance real-time drowsiness detection reliability and assess fitness to drive in OSA drivers. Full article

Traumatic cervical pathology is an injury that emerges due to trauma or being subjected to constant impact loading, affecting the ligaments, muscles, bones, and spinal cord. In contact sports (the practice of American football, karate, boxing, and motor sports, among others), the reporting of this type of injury is very common. Therefore, it is imperative to have preventive measures so players do not suffer from such injuries, since bad practices or accidents can put their lives at risk. This research evaluated cervical and skull biomechanical responses during a frontal impact, taking into consideration injury caused by wear on the intervertebral disc. Intervertebral disc wear is a degenerative condition that affects human mobility; it is common in people who practice contact sports and it can influence the response of the cervical system to an impact load. The main objective of this work is to evaluate the effects caused by impact loading and strains generated throughout the bone structure (composed of the skull and the cervical spine). The numerical evaluation was developed using the finite element method and the construction of the biomodel from computational axial tomography. In addition, the numerical simulation allowed us to observe how the intervertebral disc’s wear affected the cervical region’s biomechanical response. In addition, a comparison could be made between a healthy system and a disc that had suffered wear. Finally, the analysis provided information valuable to understanding how an impact, force-related injury can be affected and enabled us to propose better physiotherapeutic procedures. Full article

The employment of breast silicone implants, both in aesthetic and reconstructive medicine, is widespread thanks to their recognized biocompatibility and durability. Some critical situations, for example, in the case of accidental impacts, may induce concerns by potential patients about their use. Dynamic tests reproducing frontal impacts at speeds up to 90 km/h, with anthropomorphic dummies carrying 330 cc prostheses and wearing safety belts, were conducted. Tests showed a significant probability of internal gel loss following implant damage at the highest speed. Moreover, considering that prostheses may remain implanted for many years, the effects of accelerated aging at 37 °C, 60 °C, 75 °C and 90 °C in physiological solution were also investigated. Tensile tests of the shell material and compressive tests of the full prosthesis showed evidence of variation in the prostheses’ mechanical characteristics after aging, which affects their stiffness, deformability and strength. These results stress the importance of medical investigations for possible damages of the implanted prostheses in the case of an accident. Full article

Recently, there has been a considerable rise in the popularity and use of electric scooters. Because of this, the number of accidents involving them has also risen. Head and neck injuries are the most common. The aim of the study was to determine the most frequent craniofacial injuries resulting from accidents involving electric scooters, and to identify the risk factors directly related to their placement and severity. The study carried out a retrospective analysis of the medical records of patients of the Clinic of Maxillofacial Surgery over 2019–2022, in terms of craniofacial injuries suffered as a result of e-scooter-related accidents. In the study population (31 cases), of which 61.3% were men, the median age was 27 years. At the time of the accident, 32.3% patients were under the influence of alcohol. Accidents were most common in the 21–30 age group; more often than not, they occurred during warm months and on weekends. The study identified a total of 40 fractures in the patients. The most common craniofacial injuries were mandibular fractures (37.5%), zygomatic-orbital fractures (20%) and frontal bone fractures (10%). A multidimensional correspondence analysis was also performed, which showed that at an age of under 30, alcohol consumption and female gender were associated with a higher likelihood of mandibular fracture. Proper education on the risks associated with the use of e-scooters is essential, with particular emphasis on the impact of alcohol on the driver. It is important to develop diagnostic and therapeutic algorithms for doctors, both in ED and in specialised departments. Full article

In this paper, a potential use of the basic parameters of a road collision in a forensic activity was analyzed. A selected case of a frontal, eccentric, and oblique collision between two motor vehicles was analyzed from the point of view of both a computer simulation and a model. The case has been presented as an attempt to identify the collision parameters necessary to conduct the analytical calculations useful in analyzing specific road accidents. The simulation results were obtained in V-SIM software, which is widely used in collision reconstructions by forensic experts and appraisers. It was further analyzed from the point of view of a mathematical model, with the use of the force–impulse method and avoiding the use of the coefficients of restitution in the normal and tangential directions versus the adopted coordinate frame. In the analytical calculations, apart from the masses and the velocities of vehicles, the collision angles and the vicarial coefficient of adhesion between the colliding vehicles (µ) are also important. The approach presented in the article enables an expert to verify the obtained results of a computer program simulation. Full article

This research assessed a mechanical coupling for the ISOFIX Child Restraint System using the Finite Element Method (FEM) in a critical condition (simultaneous frontal and lateral collision). The mechanism was designed according to the R129 standard, and it consists of a set of springs and dampers that allows displacements in the three Cartesian axes (x, y, z) to dissipate a portion of the energy produced by a traffic accident. Two case studies are presented. The first one evaluates the behavior of the mechanism by applying the equivalent weight of a child and the LBB during a frontal and lateral impact according to the FMVSS 213 standard. The second evaluates the injuries generated in the head, neck, and thorax with a six-year Hybrid III model during a frontal impact when implementing the coupling system. The outcomes show that both axes reach a maximum deceleration of 23 G, and it remains from 17 G to 21 G in 30 ms. After 65 ms, it decreases from 17 G to 0 G. Overall, the injury rates are compared when using mechanical coupling with LBB and only LBB to analyze the system’s efficiency, showing a significant reduction in head and neck injuries, obtaining a 24% variation in the HIC_36, and reducing the neck range motion by 19.3°. Full article

The objective of this study was to apply an innovative technique to manufacture a plastic automotive component to reduce its weight and costs, and guarantee its design was safe. A frontal impact sled test was simulated, and the damages to the occupant’s legs were assessed, with specific reference to the dashboard’s glove box. The replacement of the current glove box with a new component fabricated using additive manufacturing was analyzed to evaluate its passive safety performance in the event of an automobile accident. The materials analyzed were polyamide and polypropylene, both reinforced with 5% basalt. The stiffness of the system was previously characterized by reproducing a subsystem test. Subsequently, the same rating test performed by the Euro NCAP (New Car Assessment Program) was reproduced numerically, and the main biomechanical parameters required by the Euro NCAP were estimated for both the current and the additive production of the component. Full article

Vehicle occupants were killed in 33% of all traffic accidents in Japan in 2017. Of the vehicles in vehicle-to-vehicle accidents, 54% were impacted from the front. In frontal impact accidents, when the lap belt moves away from the iliac crests of the pelvis of a vehicle occupant, the belt moves directly into the abdomen. Here, we investigated causes of abdominal injuries to vehicle occupants, because the abdomen is associated with the highest rates of severe injury and fatality. The purpose of this study was to clarify the correlation between downward movement of the seat and of the lap belt away from the iliac crests of a human occupant of a car, in the event of a frontal impact. We investigated this phenomenon by conducting simulations using an anthropomorphic 50th percentile male (AM50) human model wearing a three-point seatbelt. We set two deformable seat conditions: Vertical movement and lean forward movement. Our results revealed that the lap belt came off from both of the iliac crests during lean forward movement but only from one of the iliac crests during vertical movement. We concluded that abdominal injuries can be caused by downward movement together with forward rotation in the seat during vehicle-to-vehicle frontal impacts. Full article

The aim of this paper is to assess the safety performance of a lightweight hydrogen fuel cell city concept vehicle entitled Microcab [1]. The Microcab is a lightweight 4 seat hydrogen fuel cell concept vehicle with a combined mass (excluding passengers) of less than 800kg. The Microcab has a range of 180 miles; it includes a hydrogen fuel tank pressurised to 350 bar. The research focuses on urban accident scenarios; including frontal, lateral and compatibility loadcases. All loadcases utilise urban speeds, i.e. speeds ranging up to 40km/h for frontal impacts. The crashworthiness of the Microcab has been analysed using explicit non-linear Finite Element Analysis (FEA). The study concludes that within the limitations of the material parameter definitions and mass distributions; the crashworthiness in connection with urban accident scenarios is good. This includes aspects such as vehicle compatibility loadcases and protection of the hydrogen fuel tank e.g. for intrusion. The outcome of the study also suggests structural refinements for the future Microcab final production model; with an aim of further improving the vehicles’ crashworthiness. These refinements include raising the primary front crash structure to better align it with that of a Sports Utility Vehicle (SUV) as well as bracing the fuel cell area in case of a rear impact in order to better protect this vital component. It is also suggested that adhesive joints were suitable for structural crash integrity in all the loadcases studied within this paper, including low speed impact for repairability. A structural optimisation study has also been undertaken utilising Design Of Experiments (DOE), shape- size- and topology optimisation. DOE was employed to further improve the stiffness of the chassis with respect to safety, whilst minimising the mass increase. Topology optimisation models based on the maximum crash force magnitudes computed in the initial part of the study were also setup; the results of these suggested future changes to the Microcabs’ floor layout could be utilised to further enhance the vehicles crashworthiness. Full article