Modeling and control of vehicle suspension system are high noteworthy from safety to comfort. In this paper, an analytical nonlinear half-vehicle model which is included quadratic tire stiffness, cubic suspension stiffness, and coulomb friction is derived based on fundamental physics. A hybrid fuzzy logic approach which combines fuzzy logic and PID controllers is designed for reducing the vibration levels of passenger seat and vehicle body. Performances of designed controllers have been evaluated by numerical simulations. Comparisons with classical PID control, Fuzzy Logic Control (FLC) and Hybrid Fuzzy-PID control (HFPID) have also been provided. Results of numerical simulations are evaluated in terms of time histories of displacement and acceleration responses and ride index comparison. A good performance for the Hybrid Fuzzy-PID controller with coupled rules (HFPIDCR) is achieved in simulation studies despite the nonlinearities.

In internal combustion engines, friction losses caused by piston ring and cylinder liner pair account for approximately 20% of total mechanical friction losses as reported in literature. A reduction in friction between piston ring and cylinder liner pair would therefore result in higher efficiency, lower fuel consumption and reduced emissions. In this study, the effects of different types of fuel which is contaminated to cylinder oil have been tested for investigating the friction behavior between piston ring and cylinder liners pair by a reciprocating tester depending on the load, revolution and temperature. The results showed that lubricant type and revolution have been found significant on friction behavior.

Background/Aim: Adipose-derived mesenchymal stem cells (AD-MSCs) have gained popularity for use in treating osteoarthritis (OA) although their long-term effects remain unsatisfactory for treating the end stages of OA. However, clinically injectable polyacrylamide hydrogels (PAHGs) remain in the joint indefinitely, which could make them ideal candidates as AD-MSC carriers. Our aim was to evaluate whether combinations of PAHG and AD-MSCs have positive effects on cell viability, thereby the potential of this combination prior to clinical use in OA treatment in addition to the effects of PAHG on human osteoblasts (HOBs). Methods: Cell lines of AD-MSCs of canine origin and HOBs were culture-expanded and seeded in 96well plates (0.5 x 10 5 cells/well). The PAHG substrate at doses of 2, 6, 10, 20, or 40 µL per 200 µL of sample were added to the wells, and their effects were compared to the positive and negative control groups and among substrate doses for each cell line. The experiments were repeated three times, and cell viability was studied using tetrazolium (MTT) method. Results: Cell viability in all dose groups was significantly greater than that of their negative control groups for both cell lines (P < 0.001). Among the different dose groups, significant dose-dependent viability increases were only observed for the HOB cell line (P < 0.001). The PAHG substrate was not lethal to AD-MSCs or HOBs up to the maximum assayed doses and had positive effects on the viability of these cell lines, including slight increases in proliferation. Conclusion: Combination of PAHG with AD-MSCs may have positive long-term effects for OA treatment. However, further trials are needed.