A quasi-continuum (QC) method based on the embedded atom method (EAM) potential was employed to investigate the fatigue crack growth and expansion characteristics of single-crystal Fe and Ni under cyclic loading modes I and II. In particular, the crack growth and expansion characteristics of Fe and Ni under cyclic loading were evaluated in terms of atomic stress fields and force–distance curves...

Eyes and brains have evolved so as to extract from the natural word the sensible order that is crucial for survival. Accordingly, it makes good sense to consider the ecological basis of vision, arguing more or less implicitly for forces shaping visual organisation and processing that act with evolutionary or developmental timescales. Of course, visual systems are not normally blind to many quit...

Northeastern University Department of Electrical and Computer Engineering Doctor of Philosophy in Electrical Engineering Convex Relaxations for Robust Identification of Hybrid Models by Necmiye Ozay In order to extract useful information from a data set, it is necessary to understand the underlying model. This dissertation addresses two of the main challenges in identification of such models. F...

Polymer science is a so pervasive and relevant discipline in the contemporary scenario that it is unnecessary to spend much words to emphasize its role. As a matter of fact, it has been proposed to designate our time as the polymer age, to mark its distinction from previous mankind eras dominated by a series of diverse materials (the stone, the bronze, the iron ages) and to remark that our life...

We consider the 2 x 2 hyperbolic system of isentropic gas dynamics, in both Eulerian or Lagrangian variables (also called the p-system). We show that they can be reformulated as a kinetic equation, using an additional kinetic variable. Such a formulation was first obtained by the authors in the case of multidimensional scalar conservation laws. A new phenomenon occurs here, namely that the adve...

The purpose of this paper is to extend the results of [4] in order to achieve more versatile, convenient stability criteria for a wide class of finite-difference approximations to initial-boundary value problems associated with the hyperbolic system u, = Aux + Bu + i in the quarter plane x > 0, / > 0. With these criteria, stability is easily established for a large number of examples, where man...

Convenient stability criteria are obtained for difference approximations to initialboundary value problems associated with the hyperbolic system u, — Aux + Bu + t in the quarter plane x > 0, I > 0. The approximations consist of arbitrary basic schemes and a wide class of boundary conditions. The new criteria are given in terms of the outflow part of the boundary conditions and are independent o...

Vorticity dynamics of the three-dimensional incompressible Euler equations is cast into a quaternionic representation governed by the Lagrangian evolution of the tetrad consisting of the growth rate and rotation rate of the vorticity. In turn, the Lagrangian evolution of this tetrad is governed by another that depends on the pressure Hessian. In this representation, fluid particles carry ortho-...

Vorticity dynamics of the three-dimensional incompressible Euler equations is cast into a quaternionic representation governed by the Lagrangian evolution of the tetrad consisting of the growth rate and rotation rate of the vorticity. In turn, the Lagrangian evolution of this tetrad is governed by another that depends on the pressure Hessian. Together these form the basis for a direction of vor...

Writing instruction for engineering students involves differing perspectives and in some cases conflicting goals of many stakeholders including future employers, accrediting associations, writing center staff, and faculty in engineering, English, composition, and technical writing programs. These perspectives and conflicts can be addressed through a bottomup approach to WAC and WID: coursespeci...