摆辗机摆头运动学分析和运动轨迹的数值模拟

从摆动辗压机中摆头的结构出发．通过运动学分析给出摆头运动方程，采用数值方法对摆头运动轨迹进行数值模拟，为摆辗机结构设计和摆辗工艺的合理应用提供科学依据。     

Human Volunteer Kinematics in Rear-End Sled Collisions

Validation of new crash test dummies for rear-end collision testing requires human response data from pertinent test situations. Eleven human volunteers were exposed to 23 low-speed rear impacts to determine human response in well-defined test seats, and to quantify repeatability, variability and the effect of seat design on human response.

The results showed vertical motion of the volunteers’ H-point caused by ramping up along the seat, and an upward motion of the volunteers’ torso and head. The latter was caused by a combination of ramping up along the seatback and straightening of the thoracic kyphosis. During the first 100 ms, the volunteers flexed their necks. Thereafter, the volunteers extended their necks. These new data have proven to be useful in validation of rear-impact dummies.     

Fractionating dead reckoning: role of the compass,odometer, logbook,and home base establishment in spatial orientation

Rats use multiple sources of information to maintain spatial orientation. Although previous work has focused on rats’ use of environmental cues, a growing number of studies have demonstrated that rats also use self-movement cues to organize navigation. This review examines the extent that kinematic analysis of naturally occurring behavior has provided insight into processes that mediate dead-reckoning-based navigation. This work supports a role for separate systems in processing self-movement cues that converge on the hippocampus. The compass system is involved in deriving directional information from self-movement cues; whereas, the odometer system is involved in deriving distance information from self-movement cues. The hippocampus functions similar to a logbook in that outward path unique information from the compass and odometer is used to derive the direction and distance of a path to the point at which movement was initiated. Finally, home base establishment may function to reset this system after each excursion and anchor environmental cues to self-movement cues. The combination of natural behaviors and kinematic analysis has proven to be a robust paradigm to investigate the neural basis of spatial orientation.     

Influence of the Anterior and Middle Cranial Fossae on Brain Kinematics During Sagittal Plane Head Rotation

A 2D physical model of the human head was used to investigate how the irregular skull base structure affects brain kinematics during sagittal plane head dynamics. The model consisted of a rigid skull vessel with interchangeable skull base structures. One version of the model used a skull base mimicking the irregular geometry of the human. A second version used a skull base structure approximating the anterior and middle fossae as a flat surface. Silicone gel simulated the brain and was separated from the vessel by a paraffin layer which provided a slip condition at the interface between the gel and vessel. The model was exposed to 7600 rad/s² peak rotational acceleration with 6 ms pulse duration and 5° forced rotation. After 90° free rotation, the model was decelerated during 30 ms. Five repeated tests were conducted with each version. Rigid body displacement, shear strain and principal strains were determined from high-speed video recorded trajectories of grid markers located at different positions in the surrogate brain. The humanlike skull base reduced peak displacements of the inferior surfaces of the temporal and frontal lobes up to 87% and 48%, respectively. Up to 48% and 36% higher peak strains were obtained in the frontal and superior regions of the surrogate brain in the version containing the humanlike skull base. In contrast, the humanlike skull base decreased peak strain up to 28% in the central region of the surrogate brain. The results indicate that the irregular skull base offers natural protection of nerves and vessels passing through fissures and foramina in the cranial floor but also that it affects kinematics in different regions throughout the cerebrum. Implications of these results are discussed with respect to brain injury and modeling of head impact.