Rear Cabin Research Articles

Process of cabin smoke and flame propagation and emergency evacuation characteristics of personnel during sudden fire of Boeing 737

Cabin fires and emergency evacuation of personnel are hot topics in aviation safety. To obtain the characteristics of cabin fires and personnel evacuation, a study is conducted on the Boeing 737, and the results show that after the fire occurs, smoke first spreads towards the top and then rapidly spreads towards both ends of the cabin. The propagation speed of smoke is greater than that of flame, as the spread of flame is limited by the oxygen concentration in the cabin. Although the partition between business class and economy class has a significant obstructive effect on the spread of smoke, the effectiveness of the partition in blocking heat and high temperature transfer is limited. When a fire occurs in the cabin and emergency evacuation is required, it takes 80.5 s to evacuate all personnel when all eight cabin doors are open. But when emergency hatches fail to open, it is not until 164.8 s that all personnel in the cabin are evacuated, mainly because people in the economy class can only be evacuated through the front and rear cabin doors, which reduces the evacuation rate. The research on cabin fire and emergency evacuation of personnel can provide reference for fire monitoring and firefighting rescue.

Ambulance Traffic Crashes in Japan: Characteristics of Casualties and Efforts to Improve Ambulance Safety

Background An ambulance traffic crash not only leads to injuries among emergency medical service (EMS) professionals but also injures patients or their companions during transportation. We aimed to describe the incidence of ambulance crashes, seating location, seatbelt use for casualties (ie, both fatal and nonfatal injuries), ambulance safety efforts, and to identify factors affecting the number of ambulance crashes in Japan. Methods We conducted a nationwide survey of all fire departments in Japan. The survey queried each fire department about the number of ambulance crashes between January 1, 2017, and December 31, 2019, the number of casualties, their locations, and seatbelt usage. Additionally, the survey collected information on fire department characteristics, including the number of ambulance dispatches, and their safety efforts including emergency vehicle operation training and seatbelt policies. We used regression methods including a zero-inflated negative binomial model to identify factors associated with the number of crashes. Results Among the 726 fire departments in Japan, 553 (76.2%) responded to the survey, reporting a total of 11,901,210 ambulance dispatches with 1,659 ambulance crashes (13.9 for every 100,000 ambulance dispatches) that resulted in a total of 130 casualties during the 3-year study period (1.1 in every 100,000 dispatches). Among the rear cabin occupants, seatbelt use was limited for both EMS professionals (n = 3/29, 10.3%) and patients/companions (n = 3/26, 11.5%). Only 46.7% of the fire departments had an internal policy regarding seatbelt use. About three-fourths of fire departments (76.3%) conducted emergency vehicle operation training internally. The output of the regression model revealed that fire departments that conduct internal emergency vehicle operation training had fewer ambulance crashes compared to those that do not (odds of being an excessive zero −2.20, 95% CI: −3.6 to −0.8). Conclusion Two-thirds of fire departments experienced at least one crash during the study period. The majority of rear cabin occupants who were injured in ambulance crashes were not wearing a seatbelt. Although efforts to ascertain seatbelt compliance were limited, Japanese fire departments have attempted a variety of methods to reduce ambulance crashes including internal emergency vehicle operation training, which was associated with fewer ambulance crashes.

차량용 공기 순환 장치가 후석 승객의 온열 쾌적성에 미치는 영향에 관한 연구

Recently, automotive industry in Southeast Asia and India has enlarged and lifestyle has been changed, with time spending in an automotive showing a gradual increase. Accordingly, thermal comfort that passengers feel inside the cabin of an automotive is more important than other region. Current air-conditioning system is dependent on the cool-down performance of an HVAC located inside the front instrument panel that supplies cold air from the front cabin to the rear cabin. Therefore, front seat passengers and rear seat passengers can feel thermal comfort quite differently because of solar radiation through windows, air flow velocities, and blowing air path in the cabin. In this study, to increase thermal comfort for rear passengers, especially those in 2nd row and 3rd row seats, an air-circulator was developed. The air-circulator was subjected to computational fluid analysis to find the appropriate airflow volume, air distribution rate, and air direction for passengers in 2nd row and 3rd row seats. Air-conditioning system cool-down performance, PMV, and subjective evaluation of thermal comfort of vehicle experiments were also carried out. As the result, roof top mounted air-circulator was optimized by computational analysis and experimental study. It was a quite good solution for improving cabin thermal comfort for passengers in 2nd row and 3rd row seats with cost effectiveness and a compact package.

Heat Strain with Two Different Ventilation Vests During a Simulated 3-Hour Helicopter Desert Mission.

BACKGROUND: The study investigated the heat strain of personnel operating in the rear cabin of a helicopter during desert-climate missions, and to what extent the strain can be mitigated by use of battery-driven ventilation vests.METHODS: Eight men undertook 3-h simulated flight missions in desert conditions (45C, 10% humidity, solar radiation). Each subject participated in three conditions wearing helicopter flight equipment, including body armor, and either: a ventilation vest with a 3-dimensional mesh (Vent-1), a ventilation vest with a foam sheet incorporating channels to direct the air flow (Vent-2), or a T-shirt (NoVent); each mission comprised a 10-min walk, followed by sitting for 30 min, kneeling on a vibration platform for 2 h, and finally 30 min of sitting. Core temperature, heart rate, skin temperatures and heat flux, oxygen uptake, sweating rate, and subjective ratings were recorded. Evaporative capacity and thermal resistance of the garments were determined using a thermal manikin.RESULTS: All subjects completed the NoVent and Vent-1 conditions, whereas in the Vent-2 condition, one subject finished prematurely due to heat exhaustion. The increase in core temperature was significantly (P 0.01) greater in Novent (0.93C) and Vent-2 (0.88C) than in Vent-1 (0.61C). Evaporative capacity was significantly higher for Vent-1 (7.8 g min1) than for NoVent (4.1 g min1) and Vent-2 (4.4 g min1).DISCUSSION: Helicopter personnel may be at risk of heat exhaustion during desert missions. The risk can be reduced by use of a ventilation vest. However, the cooling efficacy of ventilation vests differs substantially depending on their design and ventilation concept.Grönkvist M, Mekjavic I, Ciuha U, Eiken O. Heat strain with two different ventilation vests during a simulated 3-hour helicopter desert mission. Aerosp Med Hum Perform. 2021; 92(4):248256.

Study on local thermal sensation and model applicability in vehicle cabin under different driving states

An experimental study on the dynamic thermal environment and front and rear occupants’ local thermal sensation of the vehicle cabin in automatic air conditioning mode under different driving states in summer is conducted. Experimental results show: air temperature, occupant skin temperature and local thermal sensation are all affected by crew position, body part and driving status. Driving increases the heat flux between the vehicle body and the air outside. Driving helps reduce body part differences and improves uniformity of front and rear cabin. Local thermal sensation and local skin temperature show a good linear relationship. But the linear correlation coefficient is affected by crew position, body part, driving state and air conditioning conditions. When the air conditioning system in vehicle cabin adopts the automatic mode, the local thermal sensation under different driving status of the same body part can be unified under the same one exponential function. And the static model is more suitable to describe local thermal sensation than the dynamic model, which means that only need to consider non-uniformity and ignore transient. Substituting the local skin temperature under driving condition into a static model fitted with idle condition can predict the body’s local thermal sensation well.

Safety issues faced by paramedics in ambulances in Saudi Arabia

Background: According to the National Highway Traffic Safety Administration, the risk of accident-related fatalities in the rear of an ambulance is more than five times greater than it is in the front seat. The main objective of this research was to assess ambulance design safety and identify limitations that endanger emergency medical service (EMS) providers in Saudi Arabia during their day-to-day work, especially in the rear cabin. Methods: An observational cross-sectional study was conducted via online surveys filled by EMS providers and a checklist filled out by supervisors, section heads, and chiefs, in Saudi Arabia, from March 2020 to April 2020. Additionally, a retrospective review was also conducted on reports by various US and international safety organizations. Results: A total 861 participants (832 surveys and 29 checklists) were enrolled. EMS providers expressed significant challenges in terms of ensuring their own safety as well as that of the patients due to the current ambulance design, where 79% (22/29) of checklist participants and 87% (718/861) of survey participants indicated dissatisfaction with the current ambulance designs. Conclusion: Practically, the design of the current ambulances is often unsafe for providing emergency medical treatment, and therefore the rear cabin is a dangerous environment for both the patient and the EMS provider.

Satisfaction with the performance of emergency medical services: a case study in Tabriz

Objective: Assessing patients’ satisfaction with emergency medical services (EMSs) is an important managerial point of view. The present study aimed to assess the patients’ satisfaction with EMS in Tabriz, Iran. Methods: This is a descriptive-analytic study that was done in the prehospital emergency and disaster management center of Tabriz University of Medical Sciences. In this study, from May to December 2017, we included 659 patients who were transferred to hospitals with our prehospital emergency services. A valid and reliable questionnaire was used to evaluate the satisfaction of patients about the performance of prehospital EMSs. Results: Data of 659 patients were evaluated. Trauma was the most common cause of contact with 115 and help request (33.83%). The results indicated that patients’ level of satisfaction was good and very good. The highest level of satisfaction was related to the treatment of patients and use of medical equipment in the ambulance (n=578 patients, 87.7%) as well as the treatment practiced by the emergency medical technicians (EMTs) (n=575 patients, 87.24%). However, the lowest level of satisfaction was related to the absence of an active EMT in the rear cabin when transferring patients to the hospital (n=337 patients, 51.14%) and transfer of the patient from the accident scene to the ambulance (n=410 patients, 62.21%). Conclusion: Patients’ satisfaction with EMS was optimal. The minimum and maximum satisfaction rates were related to the absence of an active EMT in the rear cabin, treatment of the patient, and use of medical equipment.

A study of snow accumulating on the bogie and the effects of deflectors on the de-icing performance in the bogie region of a high-speed train

The operation of high-speed trains in ice and snow weather results in a large amount of snow accumulation with ice on the bogies, which will pose a risk to the safety of high-speed trains. In this paper, the snow accumulating on the bogie has been investigated using a numerical simulation method based on the Realizable k - ε turbulence model and Discrete Phase Model (DPM). The accuracy of mesh resolution and methodology of CFD was validated by the experimental results of wind tunnel tests. The DPM was used to investigate the mechanism of snow accumulation on the bogie by analysing the characteristics of movement of snow particles. Based on this analysis, two deflectors with the angles of 2.58° and 5.14° were designed, and the anti-snow effect of deflectors for the bogies was compared with numerical results. The results show that lots of snow particles underneath the bogie have direct impacts on the equipment of the bogie, causing massive snow accumulation on the bottom surface. A small amount of snow particles turn back to the region above the bogie from the rear cabin cover, which leads to little snow accumulation on the upper surface of the bogie. The number of particles accumulating on the bottom surface of the bogie is much more than that on the top. Application of deflectors with different angles can improve the anti-snow performance in the bogie region of high-speed trains. The deflector with an angle of 5.14° has the better anti-snow performance. It can reduce the snow accumulation on the whole bogie surfaces by 49.34%, while on the primary heat-producing devices, such as calipers and motors, by 42.47% and 47.40%, respectively.

Częstość występowania wypadków przy pracy wśród ratowników medycznych w latach 2001–2013 na podstawie rejestru wybranego szpitala

Paramedics are exposed to a number of factors that may have a direct or indirect impact on the risk of an accident at work. The aim of the study was to analyze the incidence of accidents at work among paramedics as well as to discuss risk factors and measures to prevent such cases. The data on accidents at work were obtained from unpublished internal hospital documentation. The results were subjected to statistical analysis. In the years 2001-2013 there were 40 events, including 6 collective accidents, in which 41 paramedics of the emergency department were injured. On average, around 3 accidents involving paramedics occurred each year. The accidents happened most frequently in the evening and at night and in the winter months (statistically insignificant relationship). Incorrect behavior of the paramedics was the most common cause of an accident (75.6%) and musculoskeletal injuries (75%) most frequently of upper and lower limbs (55%) were the most common effects of an accident. In none of the cases safety regulations were breached by employees or employer. Accidents among paramedics can be prevented by changing the interior design of and the medical equipment installation in the rear cabin of the ambulance, conducting regular training to upgrade the skills of paramedics and enriching their knowledge about health and safety in their widest meaning. Med Pr 2016;67(2):213-221.

Impact of a three-dimensional air-conditioning system on thermal comfort: An experimental study

This paper investigates the impact of a three-dimensional (3D) air-conditioning (AC) system on cabin thermal comfort. Current AC systems are dependent on the cooling performance of Heating, Ventilation, and Air-Conditioning (HVAC) systems located inside the front instrument panel and supplying cold air from the front to the rear cabin. This results in a difference in perceived thermal comfort between the front and back seats due to a number of factors, including solar radiation through the windows, blower air path, and individual environmental differences. The 3D AC system was designed to improve the thermal comfort of passengers. In order to simulate the 3D AC system, an auxiliary blower was adapted for rear passengers. A cooling performance test and thermal comfort evaluation were conducted, with the blower at various positions in the cabin. According to the experiment results, four positions of the auxiliary blower showed cooling comfort ratings similar to those of the current HVAC system environment, and the thermal comfort ratings in the 3D AC experiment showed improvement. In other words, 3D AC system can reduce energy consumption, because it can reach the set temperature with less AC system operation.

Aerodynamic Drag Reduction for a Generic Truck Using Geometrically Optimized Rear Cabin Bumps

The continuous surge in gas prices has raised major concerns about vehicle fuel efficiency, and drag reduction devices offer a promising strategy. In this paper, we investigate the mechanisms by which geometrically optimized bumps, placed on the rear end of the cabin roof of a generic truck, reduce aerodynamic drag. The incorporation of these devices requires proper choices of the size, location, and overall geometry. In the following analysis we identify these factors using a novel methodology. The numerical technique combines automatic modeling of the add-ons, computational fluid dynamics and optimization using orthogonal arrays, and probabilistic restarts. Numerical results showed reduction in aerodynamic drag between 6% and 10%.

Noise, Vibration and Harshness (NVH) Study on Malaysian Armed Forces (MAF) Tactical Vehicle

Noise, Vibration and Harshness (NVH) is the study and modification of the noise and vibration characteristics of vehicles, particularly cars and trucks. NVH parameters which consist of noise (unwanted sound), vibration (mechanical oscillation) and harshness (severity or discomfort of noise or vibration) need to be evaluated in order to improve comfort and safety levels for vehicle occupants. In this paper, NVH study was conducted on Malaysian Armed Forces (MAF) tactical vehicles in order to ensure that the vehicles meet the requirements of the Occupational Safety and Health Administration (OSHA) and Directive 2002/44/EC. The project aim was to identify the preferable solution that can improve the NVH parameters of the vehicles in accordance to the standard and test protocols. A 4x4 Troop Transporter vehicle which carried 8 persons at the rear cabin was used in the NVH testing. The vibration parameters studied are hand arm vibration (HAV), focussing on vibration on the steering wheels of the vehicle, and whole body vibration (WBV), focussing on vibration on the seats. For noise, it was measured at the driver cabin and rear cabin of the vehicles. From the results, the HAV value for driver during idle speed was found to be higher than the others velocity. For WBV, vibration value for passenger 1 in rear cabin was highest compared to the other WBV test points.

1210 セミアクティブサスペンションを用いたトラクタの乗り心地改善

Recently, the development stage of agricultural vehicles such as the tractor has been focused on new demands to improve the cabin environment. Especially, the ride quality of the tractor is been looking for as an important factor. For this purpose, rubber bushes have installed between the cabin and the frame of the tractor to reduce road vibration to the cabin. However, this device doesn't sufficiently suppress vibration and there's a need to improve from a driver's standpoint. This paper shows the method to improve the ride quality by reducing the road vibration installing a semi-active suspension at the rear cabin mount position of the tractor. We investigated the effect of decrease in vibration of semi-active suspension applied the sky-hook control by an experiment and simulation method at one degree of freedom model, and driving test. The result shows that the semi-active suspension applied the sky-hook control will be able to realize the decrease in vibration.

Of human bandage

Of human bandage

Pulmonary fat and bone marrow embolism in aircraft accident victims

On 28 November 1979, an Air New Zealand DC10 aircraft crashed into Mt Erebus, Antarctica with the loss of 257 passengers and crew. Postmortem examinations were carried out on 231 victims in Auckland, 4641 kilometres north of the crash site, and lung tissue was present in 205 cases. Pulmonary fat emboli were present in 134 cases (65%), pulmonary bone marrow emboli in 60 (29%) and pulmonary edema in 76 cases (37%). Clear relationships were demonstrated, firstly between the extent of fat and bone marrow embolism, secondly between the extent of fat and bone marrow embolism and the presence of pulmonary edema, and thirdly between the extent of fat and bone marrow embolism and the extent of cardiovascular damage. It was apparent that death had occurred immediately following impact, and the extent of fat and bone marrow embolism varied inversely with the severity of the injuries found. The most severely injured victims were those seated in the rear cabin of the aircraft suggesting that this was the site of impact with the ground. Our studies show that pulmonary fat embolism occurs very rapidly after severe injury and is followed by increasing numbers of fat and bone marrow emboli depending on the nature of the mortal injuries.