Search Results (98)

Research on helicopter stability is essential for the design of flotation systems and serves as a primary basis for evaluating wind and wave resistance. The drainage volume method and fluid–solid coupling method are commonly used for calculating floating characteristics. However, the drainage volume method ignores the flexibility of airbags and their interaction with the helicopter, while the fluid–solid coupling method is computationally intensive. In contrast, the analysis of a helicopter’s hydrostatic floating characteristics is a static problem. It suffices to obtain relevant results when the helicopter reaches a stationary state, without the need to accurately simulate the dynamic process of achieving that state. Therefore, this paper proposes an equivalent calculation method, in which the hydrostatic effect of water on the helicopter is represented by the hydrostatic pressure applied across the entire flotation system. The finite element method (FEM) is then employed to determine the final static state, and the results are compared with those from the drainage volume method and available experimental data to validate the reliability of the proposed approach. To elucidate the influence mechanism of airbags and flexible connecting straps on the lateral static stability of helicopters, this paper analyzes airbag positions at various heeling angles and examines the impact of different internal airbag pressures. The results indicate that the main factor affecting lateral static stability is the displacement of the airbags. This displacement causes variations in the airbag’s buoyancy and center of buoyancy, thereby reducing the lateral heeling moment. Full article

Snowboard Big Air (SBA), recognized as an Olympic discipline since 2018, emphasizes maneuver difficulty as a key scoring criterion, requiring athletes to integrate technical skill with adaptive responses to dynamic environments in order to perform complex aerial rotations. The takeoff phase is critical, determining both flight trajectory and rotational performance through coordinated lower limb extension and upper body movements. Despite advances in motion analysis technology, quantitative assessment of key takeoff parameters remains limited. This study investigates parameters related to performance, joint kinematics, and rotational kinetics during the SBA takeoff phase to identify key factors for success and provide practical guidance to athletes and coaches. Eleven athletes from the Chinese national snowboard team performed multiple backside tricks (720°, 1080°, 1440°, and 1800°) at an outdoor dry slope with airbag landings. Three-dimensional motion capture with synchronized cameras was used to collect data on performance, joint motion, and rotational kinetics during takeoff. The results showed significant increases in most measured metrics with rising trick difficulty from 720° to 1800°. The findings reveal that elite SBA athletes optimize performance in high-difficulty maneuvers by increasing the moment of inertia, maximizing propulsion, and refining joint kinematics to enhance rotational energy and speed. These results suggest that training should emphasize lower limb power, core and shoulder strength, flexibility, and coordination to maximize performance in advanced maneuvers. Full article

Side impacts tend to produce more severe injuries than frontal collisions, particularly for vulnerable occupants such as children. Despite this, there is a limited number of studies and developments focused on side impact protection systems, and existing airbag evaluations often rely on destructive and high-cost test methods. This study introduces a novel, cost-effective, and nondestructive experimental testbed designed to evaluate curtain airbags for vehicles in segments B, C, D, and E. The main objective is to develop an adjustable mechanical structure that replicates the side frame geometry of multiple vehicles, allowing the mounting and evaluation of various curtain airbags under realistic conditions. The prototype, capable of withstanding deployment forces of up to 7000 N, was tested with a 3-year-old child dummy, recording a peak head acceleration of 136.17 g, corresponding to AIS level 2. Deployment speeds reached 7.77 m/s, with inflation times between 29 and 36 ms—values that fall within the range reported in previous experimental and numerical studies. The testbed demonstrated consistency in its performance metrics and offers a valuable tool for enhancing child occupant safety in side impacts. Furthermore, it provides a measurable Head Injury Criterion (HIC) range that can be used to interpret injury severity in child occupants. This work contributes significantly to the development of flexible and safe testing methodologies for side airbag systems, reducing the reliance on full-scale crash testing. Full article

Non-visual techniques for identifying sleep postures have become essential for enhancing sleep health. Conventional methods depend on a costly professional medical apparatus that is challenging to adapt for domestic use. This study developed an economical airbag mattress and introduced a method for detecting sleeping positions via restricted body pressure data. The methodology relies on distributed body pressure data obtained from barometric pressure sensors positioned at various locations on the mattress. Two combinations of base learners were chosen based on the complementary attributes of the model, each of which can be amalgamated through a soft-voting strategy. Additionally, the architectures of Autoencoder and convolutional neural networks were integrated, collectively constituting the base learning layer of the model. Gradient enhancement was utilized in the meta-learner layer to amalgamate the output of the basic learning layer. The experimental findings indicate that the suggested holistic learning model has high classification accuracy of up to 95.95%, precision of up to 96.13%, and F1 index of up to 95.01% in sleep posture recognition assessments and possesses considerable merit. In the subsequent application, the sleep monitoring device identified the sleep posture and employed an air conditioner and an air purifier to create a more comfortable sleep environment. The user can utilize the sleep posture data to improve the quality of sleep and prevent related diseases. Full article

Using multi-power supply units to power large-area electrothermal films can achieve high electrothermal power under low voltage. However, this method may result in poor contact between the electrodes and the electrothermal film, especially for films with large areas and curved surfaces, as well as for power supply units with small electrode spacing. This study found that the relative deviation between the measured value (R_M) and the theoretical value (R_P) of the parallel resistance, ${\displaystyle \frac{R_M-R_P}{R_P}}$, exceeds 12.8% when powering a planar Indium Tin Oxide (ITO) electrothermal film with an area of 5 cm × 5 cm and electrode spacing of less than 0.5 cm using four or more power supply units. This deviation is significantly higher than that observed for power supply units with electrode spacing ≥0.8 cm, where ${\displaystyle \frac{R_M-R_P}{R_P}}$ is 1.4% and 0.3% for spacings of 0.8 cm and 1.1 cm, respectively. By using fine sand, springs, and airbags as power supply pedestals, close contact between the electrodes and the electrothermal film can be achieved for large-area and curved-surface films due to the deformation of the sand, springs, or airbags under the heater’s weight. When an airbag power supply pedestal with twelve power supply units is used to power the bottom of an electrothermal ceramic teacup with a 20 cm² curved ITO transparent electrothermal film, the ${\displaystyle \frac{R_M-R_P}{R_P}}$ is 13.3% and the heating temperature reaches 83.1 °C. Full article

Car safety can be enhanced by enabling the Airbag Control Unit (ACU) to adaptively deploy different charges based on the occupant’s position once the crash occurs. In this context, monitoring the occupant’s position using a sensorized seat integrated with an Inertial Measurement Unit (IMU) offers a practical and cost-effective solution. However, certain challenges still need to be addressed. The adoption of sensorized seats in research and vehicle set-up is still under consideration. This study investigates an interface device that can be reconfigured to suit almost any seat model. This reconfigurability makes it easily adaptable to new vehicles under development and applicable to any passenger seat in the vehicle. This paper details the device’s design, including its programming using calibration and monitoring features, which significantly improves its reliability compared to earlier prototypes. Extensive testing through real driving experiments with multiple participants demonstrated an accuracy range of 45–100%. The testing involved both drivers and passengers, showcasing the device’s ability to effectively monitor various in-car scenarios. Full article

The subject of the present work is the development and implementation of a novel testing facility to carry out an experimental campaign on an advanced fuselage panel manufactured from both thermoplastic and metallic materials, as well as the validation of its numerical simulation. The experimental arrangement was specifically designed, assembled, and instrumented to have multi-axial loading capabilities. The investigated load cases comprised uniaxial in-plane compression, lateral distributed pressure, and their combination. The introduction of pressure was enabled by inflatable airbags, and compression was applied up to the onset of local skin buckling. Calibration of the load introduction and inspection equipment was performed in multiple steps to acquire accurate and representative measurements. Data were recorded by external sensors mounted on a hydraulic actuator and an optical Digital Image Correlation (DIC) system. A numerical simulation of the fuselage panel and the test rig was developed, and a validation study was conducted. In the Finite Element (FE) model, several of the experimental configuration’s supporting elements and their connections to the specimen were integrated as constraints and boundary conditions. Data procured from the tests were correlated to the simulation’s predictions, presenting low errors in most displacement/strain distributions. The results show that the proposed test rig concept is suitable for stiffened panel level testing and could be used for future studies on similar aeronautical components. Full article

Road accidents are one of the leading causes of death worldwide, with significant repercussions on public health and the global economy. Fatal accidents can cause injuries in various anatomical areas with different dynamics. The thorax is one of the main sites involved in fatal accidents, due to the presence of vital organs such as the heart and lungs. Protective devices, such as seatbelts and airbags, also play a fundamental role in preventing chest injuries. However, external examination is often insufficient to determine the extent of internal trauma, resulting in significant difficulties in reconstructing the accident dynamics. In particular, in the absence of an autopsy, it is difficult to determine whether the driver or passengers were wearing protective devices, such as seatbelts, at the time of the accident. Diagnosing injuries secondary to protective devices, such as airbags, can also be complex without this assessment. Through a review of the literature, this work analyzes the different types of thoracic trauma that can be found at autopsy, providing indications to the forensic pathologist for the examination of these injuries. This review highlights the importance of the autopsy examination as a gold-standard investigation in the analysis of thoracic trauma from road accidents, in order to evaluate with certainty the injuries that caused death, and to facilitate the reconstruction of the dynamics for judicial purposes. Finally, an analysis of postmortem radiological investigations and of the role of protective measures in these events, such as the seatbelt and airbag, is provided. Full article

The expanding use of civilian unmanned aerial vehicles (UAVs) has brought forth a crucial need to address the safety risks they pose in the event of failure, especially when flying in populated areas. This paper reviews recent advancements in recovery systems designed for the emergency landing of civilian UAVs. It covers a wide range of recovery methods, categorizing them based on different recovery approaches and UAV types, including multirotor and fixed-wing. The study highlights the diversity of recovery strategies, ranging from parachute and airbag systems to software-based methods and hybrid solutions. It emphasizes the importance of considering UAV-specific characteristics and operational environments when selecting appropriate safety systems. Furthermore, by comparing various emergency landing systems, this study reveals that integrating multiple approaches based on the UAV type and mission requirements can achieve broader cover of emergency situations compared to using a single system for a specific scenario. Examples of UAVs that utilize emergency landing systems are also provided. For each recovery system, three key parameters of operating altitude, flight speed and added weight are presented. Researchers and UAV developers can utilize this information to identify a suitable emergency landing method tailored to their mission requirements and available UAVs. Based on the key trends and challenges found in the literature, this review concludes by proposing specific, actionable recommendations. These recommendations are directed towards researchers, UAV developers, and regulatory bodies, and focus on enhancing the safety of civilian UAV operations through the improvement of emergency landing systems. Full article

Cardiovascular diseases pose a significant threat to global health, and cardiac rehabilitation (CR) has become a critical component of patient care. Heart Rate Variability Biofeedback (HRVB) is a non-invasive approach that helps modulate the Autonomic Nervous System (ANS) through Resonance Frequency (RF) breathing, supporting CR for cardiovascular patients. However, traditional HRVB techniques rely heavily on manual RF selection and face-to-face guidance, limiting their widespread application, particularly in home-based CR. To address these limitations, we propose a remote human-computer collaborative HRVB system, “FreeResp”, which features autonomous RF adjustment through a simplified cognitive computational model, eliminating the reliance on therapists. Furthermore, the system integrates wearable technology and the Internet of Things (IoT) to support remote monitoring and personalized interventions. By incorporating tactile guidance technology with an airbag, the system assists patients in performing diaphragmatic breathing more effectively. FreeResp demonstrated high consistency with conventional HRVB methods in determining RF values (22/24) from 24 valid training samples. Moreover, a one-month home-based RF breathing training using FreeResp showed significant improvements in Heart Rate Variability (HRV) (p < 0.05). These findings suggest that FreeResp is a promising solution for home-based CR, offering timely and precise interventions and providing a new approach to long-term cardiovascular health management. Full article

The deployment of cluster mailboxes (CMs) in the U.S. has raised safety concerns for passengers in potential vehicular crashes involving CMs. This study investigated the crashworthiness of two types of CMs through nonlinear finite element simulations. Two configurations of CM arrangements were considered: a single- and a dual-unit setup. These CM designs were tested on flat-road conditions with and without a curb. A 2010 Toyota Yaris and a 2006 Ford F250, both in compliance with the Manual for Assessing Safety Hardware (MASH), were employed in the analysis. The simulations incorporated airbag models, seatbelt restraint systems, and a Hybrid III 50th percentile adult male dummy. The investigations focused on evaluating the safety of vehicle occupants in 32 impact scenarios and under MASH Test Level 1 conditions (with an impact speed of 50 km/h). The simulation results provided insights into occupant risk and determined the primary failure mode of the CMs. No components of the mailboxes were found intruding into the vehicle’s occupant compartment. For all considered cases, the safety factors remained within allowable limits, indicating only a marginal risk of potential injury to occupants posed by the considered CMs. Full article

Pre-impact fall detection during e-scooter riding is essential for rider safety. Both threshold-based and deep learning algorithms (supervised and unsupervised models) were developed in this study. Twenty participants performed normal driving maneuvers such as straight driving, speed bumps, clockwise roundabouts, and counterclockwise roundabouts, along with falls (abnormal driving maneuvers). A 6-axis IMU sensor (Xsens DOT, The Netherlands) was positioned at the T7 location to record data at 60 Hz. The approaches included threshold-based, supervised learning, and unsupervised learning models The threshold-based approach yielded an accuracy of 98.86% with an F1 score of 0.99, while the supervised model had a slightly lower performance, reaching 86.29% accuracy and an F1 score of 0.56. The unsupervised knowledge distillation model achieved 98.86% accuracy, an F1 score of 0.99, and a memory size of only 46 kB. All models demonstrated lead times of more than 250 ms, sufficient for airbag deployment. Full article

Research shows that treadmill shock-absorbing devices can reduce the impact of ground reaction forces on the knee and ankle joints during running. Most existing treadmills use fixed or passive shock absorption, meaning their shock-absorbing systems do not actively adjust to changes in ground reaction forces (GRFs). Methods: This study establishes a mathematical model integrating human motion biomechanics and treadmill running surfaces, analyzing the relationships between various parameters affecting the system. Ultimately, an optimal shock-absorbing treadmill control system is designed, utilizing a microcontroller as the main control unit, airbags for shock absorption, and a widely used foot pressure testing system. Objective: The goal is to more effectively prevent running injuries caused by excessive foot pressure. Compared to conventional shock absorption systems, this design features an active multilevel adjustment function with higher precision in regulation. Results: The experimental results demonstrate that the ground reaction force (GRF) generated by the optimal shock-absorbing treadmill control system is reduced by up to 10% compared to that of a conventional shock-absorbing treadmill. Conclusions: This leads to a smaller impact force on the knees due to foot pressure, resulting in better injury prevention outcomes. Full article

Active wearable devices such as protective smart belts have been proposed to reduce hip impact in the event of a fall. This study primarily evaluated the feasibility and acceptance of a specific protective belt among selected patients identified as being at risk of falling who were admitted to an ICS Maugeri Neurorehabilitation Unit from September 2022 to April 2023. According to previous institutional observations, the device was worn between the 6th and 21st days of recovery. Out of 435 admitted patients, 118 were considered eligible, but 101 declined to participate (about 50% refused to wear the belt without first trying it on; the other 50% found it too heavy or difficult to manage). Among the 17 patients who accepted (users), 9 used the belt correctly. The remaining eight patients refused to wear it after 24 h, due to discomfort. Out of 435 patients admitted, we observed at least one fall in 49 patients, of whom 5 were eligible patients; 1 was a user who had quickly refused to use the belt and fell with mild damage. Two non-eligible patients and one eligible non-user patient experienced falls resulting in hip fractures; only in the latter case could the use of the belt have limited the damage to the hip. Difficulties in recruiting patients and low acceptance of the proposed intervention present further challenges. Full article

One-shot devices are products that can only be used once. Typical one-shot devices include airbags, fire extinguishers, inflatable life vests, ammo, and handheld flares. Most of them are life-saving products and should be highly reliable in an emergency. Quality control of those productions and predicting their reliabilities over time is critically important. To assess the reliability of the products, manufacturers usually test them in controlled conditions rather than user conditions. We may rely on public datasets that reflect their reliability in actual use, but the datasets often come with missing observations. The experimenter may lose information on covariate readings due to human errors. Traditional missing-data-handling methods may not work well in handling one-shot device data as they only contain their survival statuses. In this research, we propose Multiple Imputation with Unsupervised Learning (MIUL) to impute the missing data using Hierarchical Clustering, k-prototype, and density-based spatial clustering of applications with noise (DBSCAN). Our simulation study shows that MIUL algorithms have superior performance. We also illustrate the method using datasets from the Crash Report Sampling System (CRSS) of the National Highway Traffic Safety Administration (NHTSA). Full article