Research on Neck Response of Elderly Drivers in Rear Collision.

In order to study the neck response of elderly drivers in rear collision, a finite element model for elderly neck was built. By comparing the cadaver experiment data in the literature, the simulation reliability of the head and neck model of the elderly under dynamic load was verified. Through the C-NCAP rear-end collision test on the elderly model, the study showed that the neck of the elderly driver had good dynamic response characteristics. The verified finite element model was used to analyze the head and neck collision response and injury risk of the elderly under different distances between the head and the headrest (vertical distance and horizontal distance). By analyzing the head and neck injuries of occupants at different distances, it was found that when the horizontal distance was 50 mm, and the vertical distance was between +10 and ~+20 mm, the headrest could play the best role in protecting the neck of the elderly driver and could reduce the degree of injury of the elderly driver in the process of rear collision.

Occupant kinematics and biomechanics during frontal collision in autonomous vehicles-can rotatable seat provides additional protection?

In a highly autonomous vehicle (HAV), the rotatable seat is likely to be designed to facilitate ease of communication between the occupants. We hypothesize that the protective effects of current restraint systems vary among different seating configurations and that by using the rotational seat to alter the occupant's orientation in accordance with the direction of impact, occupants will be better protected. Moreover, in HAVs, it's likely that an imminent impact could be detected at a time of 200 ms, or even longer, prior to the initial contact. The availability of this additional time could be used strategically to actively position the occupants into a safer position for impact.Finite element simulations were performed using the THUMS model to test the hypothesis. The simulation results indicated that during a frontal impact, the backward-facing occupant is safer than occupants in other seating orientations. Moreover, 200 ms is sufficient to rotate the occupant by ±45° and ±90° without introducing additional injuries. Finally, the timing of the post-rotation impact also plays a role in injury risk of the rear-facing impact. Further studies are needed to optimize the rotating seat parameters in order to maintain occupant posture and improve crash safety in HAVs.

Internal Biomechanical Study of a 70-Year-Old Female Human Lumbar Bi-Segment Finite Element Model and Comparison with a Middle-Aged Male Model.

The main purpose of this article is to study the biomechanics of spine tissue in elderly female. In this study, the L3-L5 lumbar bi-segmental finite element model for elderly female was obtained from the Advanced Human Modeling Laboratory of the Bioengineering Center at Wayne State University. The effects of flexion and extension on bone geometry, distribution of ligament fibers, location of nucleus, and changes in intervertebral disc height were studied by comparing the results obtained before and after the update of older female and middle-aged male models. For the purpose of comparing the calculated range of motion (ROM) with the experimental data, additional calculations for axial rotation and lateral bending were performed. The study found that the parameters of the model affected the deformation of the disc herniation, ligament and intervertebral disc, and the axial force carrying capacity of the model. The three predicted ROMs are usually similar to the experimental results. Only the older female model has a slightly larger ROM. Therefore, older women are more vulnerable to lumbar spine injuries than men.

A Taylor-Affine Arithmetic for analyzing the calculation result uncertainty in accident reconstruction.

In order to analyze the uncertainty of a reconstructed result, the Interval Algorithm (IA), the Affine Arithmetic (AA) and the Modified Affine Arithmetic (MAA) were introduced firstly, and then a Taylor-Affine Arithmetic (TAA) was proposed based on the MAA and Taylor series. Steps of the TAA, especially in analyzing uncertainty of a simulation result were given. Through the preceding five numerical cases, its application was demonstrated and its feasibility was validated. Results showed that no matter other methods (The IA, AA, the Upper and Lower bound Method, the Finite Difference Method) work well or bad, the TAA work well, even under the condition that the MAA cannot work in some cases because of the division/root operation in these models. Furthermore, in order to make sure that the result obtained from the TAA can be very close to the accurate interval, a simple algorithm was proposed based on the sub-interval technique, its feasibility was validated by two other numerical cases. Finally, a vehicle-pedestrian test was given to demonstrate the application of the TAA in practice. In the vehicle-pedestrian test, the interval [35.5, 39.1]km/h of the impact velocity can be calculated according to steps of the TAA, such interval information will be more useful in accident responsibility identification than a single number. This study will provide a new alternative method for uncertainty analysis in accident reconstruction.

A simple algorithm for analyzing uncertainty of accident reconstruction results.

In order to analyzing the uncertainty in accident reconstruction, based on the theory of extreme value and the convex model theory, the uncertainty analysis problem is turn to an extreme value problem. In order to calculate the range of the dependent variable, the extreme value in the definition domain and on the boundary of the definition domain are calculated independently, and then the upper and lower bound of the dependent variable can be given by these obtained extreme values. Based on such idea and through analyzing five numerical cases, a simple algorithm for calculating the range of an accident reconstruction result was given; appropriate results can be obtained through the proposed algorithm in these cases. Finally, a real world vehicle-motorcycle accident was given, the range of the reconstructed velocity of the vehicle was calculated by employing the Pc-Crash, the response surface methodology and the new proposed algorithm, the range was [66.1-67.3] km/h. This research will provide another choice for uncertainty analysis in accident reconstruction.

Demonstration of 6.25 Gbaud advanced modulation formats with subcarrier multiplexed technique on silicon Mach-Zehnder modulator.

Silicon Mach-Zehnder modulators (Si MZMs) with good linearity are designed and fabricated. 6.25 Gbaud Nyquist 16, 32 and 64-Quadrature Amplitude Modulation (QAM) optical signals were successfully generated by intensity modulation from the Si MZM, and the effective data rates are 22.61 Gb/s, 28.26 Gb/s and 33.91 Gb/s respectively. The subcarrier multiplexed technique and direct detection scheme were employed in this experiment. After 53.1 km transmission, the BERs of 16-QAM and 32-QAM are both below the 7% hard-decision forward error correction limit, while the back-to-back BER of 64-QAM is well below the 20% soft-decision forward error correction limit. These results demonstrated that the Si MZM can be used in the high-capacity low-cost short-haul intensity modulation and direct detection system.

Low-voltage, high speed, compact silicon modulator for BPSK modulation.

A low voltage, high speed, compact silicon Mach-Zehnder Interferometer (MZI) modulator for Binary Phase Shift Keying (BPSK) modulation has been demonstrated. High modulation efficiency, VπLπ equals to 0.45V·cm, was obtained in a 1mm length device owing to a higher doping concentration and low-loss traveling-wave electrode. 25 Gb/s non-return-to-zero(NRZ)-BPSK with 6Vpp RF driving signal was achieved. Driven by a very low 3Vpp RF signal, the 10 Gb/s NRZ-BPSK was also realized benefiting from the high modulation efficiency and the low-voltage driving scheme. The power consumption for the BPSK modulation was as low as 0.118 W. These results prove that the silicon modulator is suitable for advanced communication system with low power consumption.

Experimental demonstration of a single-carrier frequency division multiple address based PON (SCFDMA-PON) architecture.

We introduce a novel architecture for next generation passive optical network (PON) base on the Single-carrier Frequency Division Multiple Address (SC-FDMA) technique. Both downstream and upstream SCFDMA-PON transmissions (5 Gb/s total, 2.5 Gb/s for each user) are experimentally demonstrated over 22.2 km standard single mode fiber and an additional simulated 1:32 optical splitter. We also test the tolerance range of the synchronization error and prove it matches the cyclic prefix period in our scheme, which means the packet transmission accuracy from different optical network units can be relaxed in the upstream.

Bidirectional 60-GHz radio-over-fiber systems with downstream OFDMA and wavelength reuse upstream SC-FDMA.

We have proposed and experimentally demonstrated a 60-GHz bidirectional radio-over-fiber system with downstream orthogonal frequency division multiplexing address (OFDMA) and wavelength reuse upstream single-carrier frequency division multiple address (SC-FDMA). In the downstream, a 3-dB optical coupler is used for two-carrier injection-locking a distributed feedback (DFB) laser in order to realize the single-sideband modulation. In the upstream, the weakly modulated one of the two downstream carriers is filtered out for wavelength reuse. Transmission of 9.65-Gb/s 16-QAM downstream OFDMA on 60-GHz carrier and 5-Gb/s QPSK upstream SC-FDMA (2.5 Gb/s for each user) are both successfully demonstrated over 53-km standard single mode fiber without chromatic dispersion compensation. The crosstalk between the downstream OFDMA and the upstream SC-FDMA can be neglected.