New developments in the inelastic analysis of quasistatic and dynamic problems

The computational aspects are examined for the numerical analysis of inelastic structures and continua. In this context, the tracing of quasistatic and dynamic motions is considered with particular emphasis on the interaction of nonlinear and transient problems. In the first part, explicit and implicit solution schemes are developed for the numerical integration of inelastic first-order rte processes governing creep, viscoelasticity and viscoplasticity. In the second part, the exposition is extended to second-order inertial problems and in particular to the field of dynamic plasticity, devoting special attention to the kinematics of finite deformation problems.     

Network design taking into account breakdowns and traffic overloads

Models and algorithms are presented enabling an evaluation of the traffic efficiency of a telephone network under abnormal working conditions and an optimization of network structures with reliability requirements.     

Outcome of type I acute aortic dissection operated after 70 years of age. A retrospective study of operated dissection of the aorta in the over 70 years old]

OBJECTIVE: To evaluate the different short-term complications after in vitro fertilization and embryo transfer. DESIGN: a retrospective study on 7 years in the fertility clinic of an university hospital. MATERIALS AND METHODS: Short-term medical complications were analysed after 1500 transvaginal ultrasonographically guided oocyte retrievals. RESULTS: Ovarian hyperstimulation syndrome (1.8%), pelvic infections (0.4%), intraperitoneal bleeding (0.2%) and adnexal torsions (0.13%) were observed. One case of adnexal torsion occurred during pregnancy (0.18%). Two unusual case of bowel endometriosis were encountered (0.13%). CONCLUSIONS: Short-term medical complications after in vitro fertilization and embryo transfer are rare (2.8%). This contrast with the high rate of multifetal pregnancies which increases maternal and perinatal morbidity and mortality and must be considered as the major complication of in vitro fertilization treatment.     

Nonlinear black-box models in system identification: Mathematical foundations

We discuss several aspects of the mathematical foundations of the nonlinear black-box identification problem. We shall see that the quality of the identification procedure is always a result of a certain trade-off between the expressive power of the model we try to identify (the larger the number of parameters used to describe the model, the more flexible is the approximation), and the stochastic error (which is proportional to the number of parameters). A consequence of this trade-off is the simple fact that a good approximation technique can be the basis of a good identification algorithm. From this point of view, we consider different approximation methods, and pay special attention to spatially adaptive approximants. We introduce wavelet and ‘neuron’ approximations, and show that they are spatially adaptive. Then we apply the acquired approximation experience to estimation problems. Finally, we consider some implications of these theoretical developments for the practically implemented versions of the ‘spatially adaptive’ algorithms.     

The diagnosis of patellar luxation in small animals

A standard diagnostic procedure for patellar luxation is described. It is based upon the patellar luxations grade 1 to 4, which have been published before, and contains additional definitions in terms of the animals positioning toward the examiner.