The present study investigates the dynamic response of single-cylinder reciprocating engines. In particular, simpli ed models of the classical slider-crank mechanism are examined, which take into account the exibility of the connecting rod. Moreover, a main new feature of these models is that both the driving and the resisting moments are expressed as functions of the crankshaft motion, instead of prescribing the rotation of the crank. The equations of motion are rst derived by application of Hamilton's principle. These equations are then discretized geometrically and put in their nal form by applying Galerkin's method. Owing to the large rotations exhibited by the mechanism members and the form of the driving and the resisting moments, the resulting equations of motion involve strong non-linearities. As a consequence, their solution is obtained in both the time and the frequency domain by employing appropriate numerical methodologies. In particular, these methodologies include either determination of transient response by employing direct integration techniques or direct determination of complete branches of periodic steady state response by applying suitable methodologies. The rst set of numerical results refers to the special case where the angular velocity of the engine crank can be considered as virtually constant. This case can be analysed more easily and provides valuable insight into some important aspects of the system dynamics. Then, the emphasis is shifted to the general case, corresponding to non-ideal forcing conditions. In all cases, the attention is focused on examining the in uence of the parameters of the system on its dynamics during intervals with transient (run-up or run-down) or under periodic steady state conditions.
As Information Technology (IT) and Engineering advances are becoming widely available, other scientific disciplines are taking advantage of them. Especially, medicine can benefit greatly from applications of IT or Engineering or their combination. Nevertheless, medical professionals lack the required IT-expertise and training. This fact poses several problems, both in the initial acceptance of novel technologies and their subsequent efficient use. This work presents an IT system, as applied to Total Hip Arthroplasty (THA)preoperative planning. The system is designed to provide insight to the patient's anatomy, as well as assist the operating surgeon with the selection, design and fitting of orthopedic implants. Furthermore, special care has been given to ease of use and hiding the complexities involved when cross discipline expertise is required.
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