Numerical estimations, structural-dynamical

Fuzzy logic has its ingredients similar to the brain that deals with inexact information after the perception and fundamental inspirations about the phenomenon concerned. Fuzzy logicians have the opportunity for dynamic and numerical model free estimators for any engineering event. They are structured numerical estimators. Since, in engineering, estimations and predictions are the most... 

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The treatment of uncertainties requires the use of probabilistic methods, estimating the probability of exceeding response targets for the different performance requirements, for example, on an annual basis. The dynamic structural responses are highly nonlinear, and their time history must be found by numerical (e.g., finite elements) analysis for the duration of the earthquake. In a thorough analysis, the nonlinearity of the response is further increased when the interactions between the structure and the foundations are included. It is not possible to establish an explicit relationship between the intervening variables and the dynamic responses, and results can only be obtained in a discrete manner, given specific values of the structural variables and a particular earthquake record. Reliability calculations depend on simulations... 

In ordm to improve our teovdedge on possdble detonation medianisms, we anal3rze energetic and electronic characteristics of an e q>losive molecule by quantum chemistry calculations and spectroscopy data, the crystalline structure of energetic crystals by visualization on micro computers, their effects on experimental detonation parameter, while energy transfer processes are defined and their efficiency, if possible is estimated by molecular dynamics and numerical simulations. 

Vibratory loads induced by the impact should be evaluated by means of a specific dynamic analysis of structures and equipment, with account taken of the material properties of reinforced concrete subjected to dynamic loads (stiffness and damping). The floor response spectra should be calculated for all the main structural elements of the buildings which house safety related equipment. Appropriate transfer functions should be evaluated for the estimation of the vibratory action transferred to any safety related equipment. The numerical model should be specifically validated for the dynamic transient analysis, so as to guarantee a proper representation of the vibratory field at least in the frequency range in which the power spectrum of the load function has major contributions. 

The problems of response variability and reliability of structures with stochastic properties under dynamic loading are currently the subject of extensive research in the fields of computational stochastic dynamics and earthquake engineering. Both problems deal with the computation of the statistical characteristics of the response and have important practical applications, such as the estimation of seismic fragility curves which are used to assess the vulnerability of structures due to earthquakes. As the existing analytical methods for the evaluation of structural response variability and reliability can only be used in few special cases, this chapter is mainly focused on approximate methods and simulation. A numerical example involving a steel frame is also provided to illustrate the presented theoretical concepts. 

The possible point-defect structures, migration properties,. . . are so numerous in intermetallic compounds that experiment alone cannot solve the problem. Unfortunately, theory here is still in its infancy. For example, the commonly used Miedema and bond-breaking semiempirical models to estimate point-defect formation energies are quite contradictory. It is only recently, since the 1980s, that more sophisticated theoretical methods have been developed and seem to be able to predict point-defect structures and properties with some accuracy. Great progress can be expected from the combined use of Monte-Carlo and molecular-dynamics simulations (Rey-Losada et al., 1993). 

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