Development of face surrogate for impact protection design for cyclist
Bicycle usage for exercise, recreation, and commuting to work in Australia shows that pedal cycling is the fourth most popular activity with 10.6% increase in participants between 2001 and 2007. As with other means of transport, accident and injury becomes common although mandatory bicycle helmet wearing has been introduced. The research aims to develop a face surrogate made of sandwich of rigid foam and rubber sheets to represent human facial bone under blunt impact. The facial surrogate will serve as an important test device for further development of facial-impact protection for cyclist. A test procedure was developed to simulate the energy of impact and record data to evaluate the effect of impact on facial bones. Drop tests were performed to establish a suitable combination of materials. It was found that the sandwich structure of rigid extruded-polystyrene foam (density of 40 kg/m with a pattern of 6-mm-holes), Neoprene rubber sponge, and Abrasaflex rubber backing, had impact characteristics comparable to that of human facial bone. In particular, the foam thickness of 30 mm and 25 mm was found suitable to represent human zygoma (cheekbone) and maxilla (upper-jaw bone), respectively. Keywords—Facial impact protection, face surrogate, cyclist, accident prevention
Maxillofacial fractures sustained in bicycle accidents.
PURPOSE
The purpose of this study was to analyze maxillofacial fractures sustained in bicycle accidents by demographics, cause of injury, site and severity of fractures, injuries to other sites of the body, and treatment modalities.


PATIENTS AND METHODS
Data on 307 patients treated for maxillofacial fractures sustained in bicycle accidents in the Department of Oral and Maxillofacial Surgery, Nara Medical University from 1981 through 2009 were analyzed retrospectively.


RESULTS
The patients were 166 males and 141 females (average age, 30.9 years). Causes of injury were a fall on a level surface in 169 patients, an automobile accident in 56, fall from 1 level to another in 28, and a motorcycle accident in 24. One hundred seventy-five fractures were observed in the mandible, 117 in the midface, and 15 in the mandible and midface. In the mandible, fracture lines were exclusively observed at the condyle. In the midface, the zygoma was most frequently involved. The Facial Injury Severity Scale ranged from 1 to 7 (average, 1.88). Injuries at other sites of the body were found in 47 patients and were frequently found in automobile and motorcycle accidents. Maxillomandibular fixation was most frequently chosen in 81 patients, followed by observation in 76 and open reduction and internal fixation in 71. The Facial Injury Severity Scale was highest in patients treated by open reduction and internal fixation, followed by those treated by maxillomandibular fixation.


CONCLUSIONS
Maxillofacial fractures sustained in a bicycle accident frequently occurred by falling on a level surface and were not so serious in most cases; however, in accidents with motor vehicles, injuries to other sites of the body were observed at a higher rate.
Modeling of chemical reactors—XXIX mixing-cell model for packed bed reactors. Steady state considerations. Problems of multiplicity
Abstract The axial heat and mass transfer in tubular catalytic reactors may be described by mixing-cell model and diffusion model as well. The diffusion description yields for a strong exothermic reaction and adiabatic conditions three steady state profiles, on the other hand the mixing-cell model gives rise to more than three steady states. A simple numerical and graphical analysis for mixing-cell model is presented.