In recent years, seismic design of structures has been undergoing significant changes as a result of increasing demand for optimization and minimizing the level of damage and reducing the cost of structural repairs, the development of analytical methods and the remarkable improvements of computer performance have been among the factors which influenced the design of structures. A lot of research has been conducted on the development of better braces with perfect elastoplastic behavior. The inventions and development of buckling restrained braces have been the results of these researches. In this study, the performance of Buckling Restrained Environmental Braces (BRB) in highrise buildings were evaluated applying Nonlinear Time-history dynamics analysis with three pairs of acceleration and compared with conventional concentrically braced frame (CBF). The studied structures are 20, 40, and 60 stories building which braces were utilized peripherally. The acquired results reveal that the application of Buckling Restrained Brace Frames (BRB) instead of conventional braces frame (CBF) in high-rise steel buildings ameliorates hysteresis behavior of the braces and reduces lateral displacements and increase the capacity of base shear as well.

This paper presents delay-dependent stability analysis for some types of Nonlinear Time-delay systems. Motivated by Lyapunov-Krasovskii functionals and the related theorems on stability of Time-delay systems, we introduce a new procedure for generating such functionals. The main reason for considering Lyapunov-Krasovskii functionals is the less conservatism of this method. The obtained conditions are sufficient and local. Applying the introduced procedure on a typical system with Time-invariant parameters derives more results and a numerical example presents the capability of the method.

In this paper, an almost new control approach called terminal synergetic control which works based on user defined manifold is applied to a Nonlinear helicopter model. Stability analysis is convestigated using Lyapunov stability theory. Synergetic controller is applied to this Nonlinear fifth-order helicopter model to control height and angle. Simulation results showed that it has faster and smoother response in tracking reference inputs in comparison to sliding mode control, intelligent autopilot controller and feedback linearization method.

Recent developments in the theory of Nonlinear dynamics have paved the way for analyzing signals generated from Nonlinear biological systems. The main purpose of the present work is based on the analysis of the ECG signal, initially extracting the features of ECG, which are used for the detection and/or classification of ECGs. For this work, Correlation Dimension (D2), Largest Lyapunov Exponent (LLE), Ap-proximate Entropy (ApEn), Sample Entropy (SampEn) and Poincare plot methods were used from Nonlinear Time series analysis to characterize human ECG signals obtained from 24 hour-Holter recording. Four groups of ECG signals have been investigated. D2 and LLE are increasingly used to classify ECG signals. ECG Time series were classified according to the results obtained from computation of above chaotic features. Our results, obtained from clinical data, improved the previous studies, which allow one to distinguish between healthy group and patients groups with more confidence than the standard methods for heart rate Time series and gain more significant understanding of heart dynamics using Entropy features and Poincare plot along with D2 and LLE.

This study presents the effects of project uncertainties on non-linear Time-cost tradeoff (TCT) profile of real life engineering projects by the fusion of fuzzy logic and artificial neural network (ANN) models with hybrid meta-heuristic (HMH) technique, abridged as Fuzzy-ANN-HMH. Nonlinear Time-cost relationship of project activities is dealt with ANN models. ANN models are then integrated with HMH technique to search for Pareto-optimal Nonlinear TCT profile. HMH technique incorporates simulated annealing in the selection process of multi objective genetic algorithm. Moreover, in real life engineering projects, uncertainties like management experience, labor skills, and weather conditions are commonly involved, which affect the duration and cost of the project activities. Fuzzy-ANN-HMH analyses responsiveness of Nonlinear TCT profile with respect to these uncertainties. A comparison of Fuzzy-ANN-HMH is made with another method in literature to solve Nonlinear TCT problem and the superiority of Fuzzy-ANN-HMH is demonstrated by results. The study gives project planners to carry out the best plan that optimizes Time and cost to complete a project under uncertain environment.

Increasing number of diagnostic and therapeutic applications of finite amplitude ultrasound in medicine and biology has motivated researchers toward more accurate modeling and more efficient simulation of Nonlinear ultrasound regime. One of the most widely used Nonlinear models for propagation of 3D diffractive sound beams in dissipative media is the KZK (Khokhlov, Kuznetsov, Zabolotskaya) parabolic Nonlinear wave equation. Various numerical algorithms have been developed to solve the KZK equation. Generally, these algorithms fall into one of the three main categories: frequency domain, Time domain and combined Time-frequency domain. The intrinsic parabolic approximation in the KZK equation imposes limiting accuracy in the solution to the diffraction term of the KZK equation particularly for field points close to the source or in far off-axis region. In this work we developed a novel generalized Time domain numerical algorithm to solve the diffraction term of the KZK equation. The algorithm solves the Laplacian operator of the KZK equation in the 3D Cartesian coordinates using novel 5-point Implicit Backward Finite Difference (IBFD) and 5-point Crank-Nicolson Finite Difference (CNFD) techniques. This leads to a more uniform discretization of the Laplacian operator which in turn results in a more accurate solution to the diffraction term in the KZK equation. Comparison between results obtained with the new algorithm and the previously-published data for rectangular ultrasound sources is presented.