Human factors in design of passenger seats for commercial aircraft: A review

Seat comfort and safety research since the early part of the century is reviewed. The approach blends empirical and theoretical human factors and technical knowledge of seated humans under static and dynamic conditions experienced on commercial aircraft

Performance of the resurfaced hip. Part 1: the influence of the prosthesis size and positioning on the remodelling and fracture of the femoral neck

Hip resurfacing is an established treatment for osteoarthritis in young active patients. Failure modes include femoral neck fracture and prosthesis loosening, which may be associated with medium-term bone adaptation, including femoral neck narrowing and densification around the prosthesis stem.Finite element modelling was used to indicate the effects of prosthesis sizing and positioning on the bone remodelling and fracture strength under a range of normal and traumatic loads, with the aim of understanding these failure modes better.The simulations predicted increased superior femoral neck stress shielding in young patients with small prostheses, which required shortening of the femoral neck to give an acceptable implant–bone interface. However, with a larger prosthesis, natural femoral head centre recreation in the implanted state was possible; therefore stress shielding was restricted to the prosthesis interior, and its extent was less sensitive to prosthesis orientation. With valgus orientation, the implanted neck strength was, at worst, within 3 per cent of its intact strength.The study suggests that femoral neck narrowing may be linked to a reduction in the horizontal femoral offset, occurring if the prosthesis is excessively undersized. As such, hip resurfacing should aim to reproduce the natural femoral head centre, and, for valgus prosthesis orientation, to avoid femoral neck fracture

LANGUAGE AND IDENTITY IN THE WEDDING CEREMONY OF BATAK TOBA

In this article, my attempt is to reveal language and identity in the wedding ceremony of Batak Toba based on the consideration that language is an important part of any society, because it enables people to communicate and express themselves. Language is an important source of continuity and identity in a culture. Batak Toba is one of the ethnic groups of Batak society. Identity is very important in Batak Toba wedding ceremony. The social identity can be directly identified through the family name which is attached to every person from birth. In a wedding ceremony, the specifics of identity can be identified through the roles, action and language used. The identities of those people involved in the ceremony are really very unique and is interesting to investigate. The language expressed, the role and action done will always be related to one’s own identity. The uniqueness of identity is always related to family name of the groom and the bride giver sides. This event shows the significance of language in preserving culture and on the other way round this wedding tradition is hoped to maintain the existence of Batak Toba language

Head for high speed spinner having a vacuum chuck

The head for a high-speed spinner is characterized by a substantially cylindrical body adapted to be mounted at the distal end of a vertically oriented drive shaft. A vacuum chuck with an upwardly facing chamber is circumscribed by an annular surface for receiving in supported relation a silicon chip. An ordered array of low-pressure cavities is defined about the periphery of the body and connected in communication with the chamber via radially extended bores in order to translate low pressures to the chamber as the head is angularly displaced. A pressure differential is thereby established across the chip for securing it to the head

A case-driven hypothesis for multi-stage crack growth mechanism in fourth-generation ceramic head fracture

Background Ceramic bearings are used in total hip arthroplasty due to their excellent wear behaviour and biocompatibility. The major concern related to their use is material brittleness, which significantly impacts on the risk of fracture of ceramic components. Fracture toughness improvement has contributed to the decrease in fracture rate, at least of the prosthetic head. However, the root cause behind these rare events is not fully understood. This study evaluated head fracture occurrence in a sizeable cohort of patients with fourth-generation ceramic-on-ceramic implants and described the circumstances reported by patients in the rare cases of head fracture. Methods The clinical survivorship of 29,495 hip prostheses, with fourth-generation ceramic bearings, was determined using data from a joint replacement registry. The average follow-up period was 5.2 years (range 0.1-15.6). Retrieval analysis was performed in one case for which the ceramic components were available. Results Clinical outcomes confirmed the extremely low fracture rate of fourth-generation ceramic heads: only two out of 29,495 heads fractured. The two fractures, both involving 36 mm heads, occurred without a concurrent or previous remarkable trauma. Considering the feature of the fractured head, a multi-stage crack growth mechanism has been hypothesized to occur following damage at the head-neck taper interface. Conclusions Surgeons must continue to pay attention to the assembly of the femoral head: achieving a proper head seating on a clean taper is a prerequisite to decrease the risk of occurrence of any damage process within head-neck junction, which may cause high stress concentration at the contact surface, promoting crack nucleation and propagation even in toughened ceramics

Pre-Crash and In-Crash Car Occupant Safety Assessment

Tens of millions are annually injured in Road Traffic Accidents (RTAs) worldwide, while the estimated number of RTA fatalities amounted to 1.35 million in 2016. In Europe, car occupants hold the largest share (48%) of fatalities among all road users. The high fatality and injury numbers motivate the work of enhancing road traffic safety. A holistic safety assessment approach, considering both the pre- and the in-crash phase of a crash, has the potential to enhance real-world occupant protection evaluation, as well as facilitate the development of effective countermeasures. In standardized car occupant safety assessments, occupant surrogates of standardized anthropometries are employed in standardized postures, with the seat adjusted to a single predefined position. The vehicle is then subjected to predefined crash configurations with meticulously described impact points and angles. In contrast, real-world traffic crashes involve occupants of different shapes and sizes, who adjust the position of the seat and their posture on the seat differently, and the vehicles are subjected to diverse crash configurations (multiple impact locations, impact directions, and speed combinations). The overall aim of this thesis is to develop and apply methods, spanning from the pre-crash to the in-crash phase, capable of evaluating and enhancing the real-world occupant protection of future vehicles.The introduction of crash-avoidance systems has the potential to alter the crash configurations that future vehicles will be exposed to. A method for predicting crash configurations has been developed in this thesis and applied to highway driving, and urban intersection crashes. Performing counterfactual simulations of digitized real-world crashes, with and without the addition of a conceptual Automatic Emergency Braking system, provides a prediction of the remaining crashes. The use of a novel crash configuration definition, along with a purpose-designed clustering method, facilitates the reduction of the number of predicted crash configurations without sacrificing coverage of the diverse real-world situations. Three predicted crash configurations, representative of urban intersection crashes, were further analyzed during the in-crash phase. A Human Body Model was positioned in a wide range of occupant postures identified from the literature. The findings suggest that the lower extremity postures had the largest overall influence on the lower extremities, pelvis, and whole-body responses for all crash configurations. In the evaluated side-impacts, leaning the torso in the coronal plane affected the torso and head kinematics by changing the interaction with the vehicle’s interior. Additionally, in far-side impacts supporting the occupant’s arm on the center console resulted in increased torso excursions. Moreover, the upper extremity responses were consistently sensitive to posture variations of all body regions

ACTING ON THE NEED OF A CLIENT, CAREGIVER, AND PRACTITIONER SEATING AND MOBILITY GUIDE

There is a significant need for individuals with a disability and specific mobility limitations to require a wheeled mobility device. Wheeled mobility devices allow individuals to gain and/or maintain independence and engagement in occupations. The evaluation, prescription, and fitment of wheeled mobility devices are complex, requiring clients and caregivers to use and maintain these devices in specific ways. Barriers caregivers face can include not positioning the client properly in the wheeled mobility device, damaged or missing wheelchair parts, or improper positioning of the straps and belts, affecting posture, which could lead to secondary complications

Car Safety for Children Aged 4-12 : real world evaluations of long-term injury outcome, head injury causation scenarios, misuse, and pre-crash maneuver kinematics

Child casualties in car crashes have decreased over the years. Nevertheless, occupant safety in rear seats, especially for children 4-12 years old, needs further attention because motor vehicle crashes remain the leading cause of death and long-term health consequences for children. The aim of this thesis was to obtain comprehensive knowledge of real-life situations for restrained, forward-facing, rear-seated children aged 4-12 years, in frontal car crashes as a basis for vehicle safety improvements to reduce long-term health consequences. The thesis is comprised of four studies based on child-specific data from Sweden and the US. Study I was based on injury data from insurance claim files, covering 2619 injured children in Sweden. Study II was an experimental study of restraint misuse, including 130 Swedish children. Study III analyzed crash data included 27 cases from two US databases, to determine injury causation scenarios. Study IV was a driving study of how pre-crash maneuvers affect child occupant kinematics with 16 children included. The results of Study I emphasized the importance of looking beyond acute, severe injuries and also examine injuries (regardless of initial injury severity) resulting in permanent medical impairment. The vast majority of injuries with the higher degree of permanent medical impairment were severe injuries to the head. The most frequent injuries leading to permanent medical impairment were minor injuries to the neck and head. To reduce the risk of head injuries among children in car crashes, a fundamental step is to ensure that vehicle restraint systems are adapted to the child, physically and behaviorally, and that the child is properly restrained. An experimental study (Study II) of children using integrated booster cushions compared to aftermarket belt positioning booster cushions, showed that misuse related to buckling up, a problem for decades, can be reduced to a minimum by the design of an integrated booster cushion. Minimizing misuse will lead to increases in proper positioning of the restraint on the child and may translate to reductions in head injury risk. Therefore, car manufacturers should focus on integrated booster cushions, preferably as standard equipment. Even with proper use, however, restrained children in rear seats sustained head injuries in frontal impacts by impacting their heads on the side interior and on the seat back in front of them. Oblique impacts and pre-crash steering maneuvers contributed to both these injurycausation scenarios (Study III). Therefore, pre-crash steering maneuvers were further explored in a driving study and it was confirmed that these common pre-crash maneuvers can result in an unstable restraint situation that may potentially compromise rear occupant safety in the event of a crash (Study IV). In conclusion, the primary recommendation as a result of this research is to protect the head and neck of child occupants from both minor and severe injuries, since all severity levels of injuries may result in long-term consequences. Frontal impacts, including oblique impacts or maneuvers prior to impact, need to be addressed to develop “tolerant” restraint systems. Furthermore, it is recommendable to design and use vehicle-built-in restraint systems to improve crash safety among children, by facilitating proper use of the restraint and placement on the child, as has been previously done for front-seated adults. To incentivize vehicle manufacturers to accelerate the implementation of child safety improvements within their vehicles, an assessment of child safety for 4-12-year-old children should be included in consumer rating programs and legal requirements

Infant Positioning and Its Effect on Development and Head Symmetry

Parents that do not provide their babies with a variety of proper body positions throughout everyday activities may increase their infant\u27s risk for motor development problems and abnormal head shaping. The purpose of this scholarly project was to create parental educational materials in order to increase parent awareness and prevention of common problems due to lack of proper infant positioning in everyday activities. The methodology used was an extensive research literature review, review of current professional resources on this topic, and this therapist\u27s clinical expertise. The clinical products developed from this evidence included: A parental Developmental Care Guide which is a complete informational booklet; an abridged Back to the Basics brochure emphasizing Tummy Time in the daily care routine; and a parental educational session on positioning and infant development presented in Microsoft® Powerpoint® format with an accompanying outcome evaluation survey of the educational benefits. Proper body positioning during an infant\u27s everyday activities can support development, including head symmetry. With the Back to Sleep Campaign endorsed by the American Academy of Pediatrics (AAP), it is important to provide a variety of other body positions throughout the day when the baby is awake and engaged in infant occupations such as feeding and playing. The desired result of this scholarly project is to increase parental awareness of the importance of positioning and its effect on supporting normal infant development and head shaping. The parent educational materials (quick reference/detailed guide, power point presentation, and evaluation) developed through this scholarly project will be provided within the hospital and day care settings to promote the infant motor development and head shaping as related to the infant daily care routine

The influence of the distance between the backrest of a chair and the position of the pelvis on the maximum pressure on the ischium and estimated shear force.

PURPOSE: For some people with leg disorders, the alternative to becoming bedridden is sitting in a wheelchair for long periods of time. The purpose of this study was to investigate the relation between the backrest of a chair and the position of the pelvis on the maximum pressure at the ischium and the estimated shear force encountered while sitting in a chair.METHODS: Ten healthy males aged 22.4 +/- 2.3 years without pathologies in the leg and/or trunk participated in this study. The subjects were instructed to sit in a chair and the pressure and shear forces were measured under three sitting conditions: In the standard position, a 5 cm forward position and a 10 cm forward position. The effects of the positions of the pelvis on the maximum pressure at the ischium were measured by an instrument for measuring pressure distribution and the shear forces were estimated using an experimental model proposed by us.RESULTS: Comparisons were made among the three sitting positions; the range of displacement of the maximum pressure point was not significant. The estimated shear force on the seat was 15.5 +/- 12.4 N in the standard position, 34.4 +/- 8.5 N in the 5-cm forward position, and 53.2 +/- 16.7 N in the 10 cm forward position. There were significant differences among the three values (p < 0.01).CONCLUSIONS: Displacing the pelvis forward and leaning against the backrest tends to increase the shear force and raise the risk of decubitus ulcers