Lower extremity injuries in vehicle-pedestrian collisions using a legform impactor model

Though the bumper of a vehicle plays a major role in protecting the vehicle body against damage in low speed impacts,many bumpers,particularly in large vehicles,are too stiff for pedestrian protection.In designing a bumper for an automobile,pedestrian protection is as important as bumper energy absorption in low speed collisions.To prevent lower extremity injuries in car-pedestrian collisions,it is important to determine the loadings that car front structures impart on the lower extremities and the mechanisms by which injury is caused by these loadings.The present work was focused on gaining more insight into the injury mechanisms leading to both ligament damage and bone fracture during bumper-pedestrian collisions.The European Enhanced Vehicle-safety Committee (EEVC) legform impactor model was introduced and validated against EEVC/WG17 criteria.The collision mechanism between a bumper and this legform impactor was investigated numerically using LS-DYNA software.To identify the effect of the bumper beam material on leg injuries,four analyses were performed on bumpers that had the same assembly but were made from different materials.

Theoretical investigation of some parameters into the behavior of quantum dot solar cells

The main goal of this paper is to determine the accurate values of two parameters namely the surface generation–recombination rate and the average total number of electrons density generated in the i-region. These values will enhance the performance of quantum dot solar cells（QDSCs）. In order to determine these values, this paper concentrates on the optical generation lifetime, the recombination lifetime, and the effective density state in QDs. Furthermore, these parameters are studied in relation with the average total number of electrons density. The values of the surface generation–recombination rate are found to be negative, which implies that the generation process is dominant in the absorption quantum dot region. Consequently, induced photocurrent density relation with device parameters is determined. The results ensure that QDSCs can have higher response photocurrent and then improve the power conversion efficiency. Moreover, the peak value of the average total number of electrons density is achieved at the UV range and is extended to the visible range, which is adequate for space and ground solar applications.

The effect of multi-intermediate bands on the behavior of an InAs_(1-x)N_x/GaAs(1-y)Sb_y quantum dot solar cell

A mathematical model of quantum dot intermediate band solar cells （QDIBSCs） is investigated using two intermediate bands （IBs）. These two IBs arise from the quantum dot （QD） semiconductor material within the bandgap energy. Some parameters such as the width of the QD （WQD） and the barrier thickness or the inter-dot distances between the QDs （BT） are studied to show their influence on the performance of the QDIBSC. The timeindependent Schr6dinger equation, which is solved using the Kronig-Penney model, is used to determine the posi- tion and bandwidth energies of the two IBs. In our proposed model, the cubic shape of the QDs from InAs0.9N0.1 and the barrier or host semiconductor material from GaAs0.98Sb0.02 are utilized. It is shown from the results obtained that changing the parameters WQD and Bx has more influence on the bandwidth energy for the first IB, A 1, than in the case of the second IB, A2. The optimum power conversion efficiencies （PCEs） of the QDIBSCs with two IBs for the model under study are 58.01% and 73.55% at 1 sun and maximum solar concentration, respectively. One can observe that, in the case of the two IBs, an improvement of the PCE is achieved.