In industry, establishing methods to estimate lumbar burden is required for the safety validation of assist devices aiming at reducing the risk of low back pain in manual lifting tasks. However, estimating lumbar burden is difficult even when without using the devices. This paper proposes a method to estimate lumbar moment, one of the components of the burden, with modeling lumbar spine as an elastic beam. The modeling enables to estimate the moment without using body parameters, e.g. center of mass in link segmented models, which can affect the accuracy. Measurement experiment was conducted for estimating the moment with the proposed method under the movement of subjects’ leaning forward, backward with and without handling loads. The results indicated that lumbar moments were able to be estimated with the proposed method in their maximum bending posture, though accuracy enhancement were needed as a part of future work.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The objective of this study is to develop a new method and tools required for the evaluation of the potential benefits of pre-impact safety restraint systems. A pre-crash sled system that can reproduce controlled pre-impact braking in combination with a variety of crash pulses was built. The sled can be customized from existing vehicles to examine a variety of restraint systems. In addition, a previously validated 50th percentile male Hybrid III dummy with a modified lumbar was employed to reconstruct realistic driver’s posture changes at the pre-impact braking phase. In order to evaluate the potential benefits of a pre-crash seatbelt (PSB), the modified dummy was placed on the sled with a standard seating posture and restrained by either a conventional seatbelt (SB) or a PSB controlled by a motor in the retractor. The sled system was then programmed to reach a steady speed of 64 km/h, followed by a 0.8 g deceleration and 0.8 seconds of duration, just before colliding against the barrier at the speed of 48 km/h. Increased forward travelling of the upper body at the pre-impact braking phase with the SB was measured in comparison to the PSB case. In the PSB case, full airbag deployment occurred before body-to-airbag contact, allowing the airbag in coordination with the belt to mitigate the neck loading optimally and to reduce a 15% of chest acceleration. In the SB case, body-to-airbag contact occurred before its complete deployment, causing increased neck forces and moments as well as chest acceleration. In contrast, equivalent chest deflections for both types of seatbelts were measured. In this research, a new pre-crash sled system with the potential to evaluate pre-crash safety restraint systems was developed. Crash tests with dummies were conducted in order to examine the effectiveness of a PSB. By controlling the posture change during an emergency braking, the reduction of neck and chest injury risk in front impacts was achieved. This confirms the potential of a PSB to enhance occupant protection.
Spatial distribution of transported sediment in channels with vegetation was investigated with attention focused on sediment sorting via field observation at the Kizu River. Results are summarized as follows.(1) Cross-sectional averaged bed elevation has not been changed in Kizu River. On the other hand, cross-sectional bed geometry has been changed dramatically because of the change of spatial distribution of transported sediment.(2) Sediment deposition near the boundary between vegetated area and non-vegetated area is much and the deposited sediment is overpass load.(3) Sediment deposition at the center of vegetated area is few and the deposited sediment is wash load.(4) Bed deformation in non-vegetated are caused principally by overpass load.(5) Downstream-fining of sediment size was observed in vegetated area located near main flow.
