Magnetorheological dampers have received a great deal of attention in the last two decades due to their being a potential technology to conduct semi-active control. It is therefore vitally important to understand the dynamic behavior of such devices whose nonlinear hysteresis is a rather complicated phenomenon. Hence, this paper aims at conducting a comparative evaluation of the currently available parametric models that have been widely used to develop control algorithms that take maximum advantage of the unique features of MR dampers. The comparisons showed that the simple algebraic parametric models exhibited considerably better predictions than the much more complicated ordinary differential parametric models.

A 5-year review of 101 cases of zygomatico-orbital fractures is presented. The epidemiology, fracture patterns, treatment modalities, and complications were evaluated in this retrospective study. A majority of fractures were sustained by males and resulted from trauma inflicted during altercations and traffic accidents. The most common fracture pattern was tripod fracture and the most common associated facial fractures were mandibular fractures. Open reduction and rigid fixation was the most frequently employed treatment modality. Depending on the stability of reduced zygoma, one, two and three-point fixations were applied. Orbital floor exploration was performed in 41 cases. Ten out of 16 orbital floor bone defects required reconstruction. In these cases orbital floor was reconstructed with 1.5-mm porous polyethylene implant. Although we encountered a few complications related to the incisions for open reduction, the rate of complication in which correction was difficult (e.g. facial asymmetry) was lower with this approach when compared with the literature.

Magnetorheological (MR) dampers have attracted the interest of suspension designers and researchers because of their variable damping feature, mechanical simplicity, robustness, low power consumption and fast response. This study deals with the optimal configuration of an MR damper using the Taguchi experimental design approach. The optimal solutions of the MR damper are evaluated for the maximum dynamic range and the maximum damper force separately. The MR dampers are constrained in a cylindrical container defined by radius and height. The optimal damper configurations obtained from this study are fabricated and tested for verification. The verification tests show that the dampers provide the specified damper force and dynamic range.

Transplantation of mesenchymal stem cells promotes maturity of the distracted callus. The new experimental model, which allowed to test the mandible as a system by simulating in vivo loading conditions, revealed differences in the mechanical behavior of the halves of mandible.

In this paper, a switching control approach for active vibration isolation systems is proposed. The switching involves two regimes. In the first regime, no feedback control is applied thereby giving a low sensitivity to noise. In the second regime, active control induces improved disturbance rejection properties, but at the cost of increased noise sensitivity. Conditions for the stability of the switching closed-loop system are formulated whereas the stability analysis provides design rules for tuning the switching controller. Given this novel active vibration isolation approach, improved isolation performance is obtained with substantially less control authority in comparison to the case of linear (or non-switching) feedback control. Performance analysis is based on multi-resolution time-frequency analysis using measurements taken from a commercial vibration isolation system. Index Terms-Absolute stability, discontinuous variable gains, input-to-state stability, switching systems, vibration isolation, wavelet analysis.