HIC Values Research Articles

Laser-induced fluorescence of macerals in relation to its hydrogen richness

On the basis of results from conventional elemental analyses and a unique technique (FAMM®; fluorescence alteration of multiple macerals), using a laser fluorescence microprobe, the fluorescence characteristics of various macerals are systematically related to hydrogen content. The amount of fluorescence from inertinite and vitrinite exponentially increases with HIC values. Although liptinite has high fluorescence and high HIC values, the relationship does not follow the same trend as defined for the other maceral groups. Because petroleum yields of a maceral mainly depend upon hydrogen richness, a correlation also exists between fluorescence, and gas to oil ratios from pyrolysis. Because individual organic entities are measured, the laser fluorescence microprobe has the benefit of accommodating heterogeneous organic matter in source rocks and enables determination of oil and gas yields of specific macerals.

Surface friction in near-vertex head and neck impact increases risk of injury

A computational head–neck model was developed to test the hypothesis that increases in friction between the head and impact surface will increase head and neck injury risk during near-axial impact. The model consisted of rigid vertebrae interconnected by assemblies of nonlinear springs and dashpots, and a finite element shell model of the skull. For frictionless impact surfaces, the model reproduced the kinematics and kinetics observed in near-axial impacts to cadaveric head–neck specimens. Increases in the coefficient of friction between the head and impact surface over a range from 0.0 to 1.0 resulted in increases of up to 40, 113, 9.8, and 43% in peak post-buckled resultant neck forces, peak moment at the occiput-C1 joint, peak resultant head accelerations, and HIC values, respectively. The most dramatic increases in injury-predicting quantities occurred for COF increases from 0.0 to 0.2, while further COF increases above 0.5 generally produced only nominal changes. These data suggest that safety equipment and impact environments which minimize the friction between the head and impact surface may reduce the risk of head and neck injury in near-vertex head impact.

Magnetic properties of single-domain SrFe12O19 particles synthesized by citrate precursor technique

Nanosize particles of SrFe12O19 have been synthesized by a citrate precursor technique with various Fe/Sr ratios of 12.0 to 9.0. X-ray diffraction (XRD) studies showed the formation of ultrafine, monophasic SrFe12O19 particles with comparable unit cell parameters. Magnetic clusters were observed by scanning electron microscopy and Branauer–Emmett–Teller surface area measurements. Mossbauer results reveal the ferrimagnetic and superparamagnetic nature and the change in hyperfine parameters with decline in particle size and Fe/Sr ratios. The magnetic properties of small SrFe12O19 particles (Fe/Sr=12.0) showed a considerable enhancement in TC from a bulk value of 750–883 K measured for 20–5.7 nm XRD particle size. The shift in Curie temperature is well defined by the finite size scaling formula [TC(D)−TC(∞)]TC(∞)−1=(D/D0)−1/ν with ν=0.75–0.02 and D0=1.52 nm. The change in Hic, σs, and σr values were observed with the decline in particle size and the Fe/Sr ratios where Hic of 6500 Oe is achieved for isotropic SrFe12O19 particles with a Fe/Sr ratio of 10.8. Such changes are explained by the additional Sr leading to the formation of a nonmagnetic layer around the particles which inhibits their growth, limiting them to single-domain size.

Mechanics of a mechanically triggered airbag head restraint system for occupant protection in rear end impact

The principal objective of head restraint systems is to minimise the severity of injuries to the occupant's head and neck in the event of rear impact. This can be achieved if the headrest is of adequate stiffness, appropriately absorbs the kinetic energy through the deformation of the material ahead of the support frame, allows a steady sinking of the head relative to the torso and eliminates the head rotation. This paper assesses these attributes and develops a criterion for qualifying head restraint systems. It presents some experimental results obtained from eighteen randomly selected existing headrests and compares the mechanics of failure, energy absorption capabilities and the HIC values with the developed mechanical airbag head restraint systems proposed herein for the first time. The study shows that airbag headrests protect occupants better than the existing stiff head restraint systems found in current vehicles.