this study is a typological description of written formative feedback in an efl context in iran. twenty m.a. students of tefl participated in the study. they were required to summarize a scholarly article in each session on which the instructor would provide written corrective feedback (cf). written formative comments were extracted, coded, and categorized into various types, such as asking for...

Many physical systems can be modelled using linear 2 × 2 hyperbolic partial differential equations. The act of stabilizing systems of this type has therefore been subject to extensive research, and a number of techniques and feedback laws have been proposed in the literature. In this thesis, a full state feedback law for disturbance attenuation in such systems is derived, with actuation limited...

We try to stabilize equilibrium solutions of physical models described by a class of coupled first-order linear partial differential equations with nonlinear boundary conditions. These systems are distributed parameter systems in which spatio-temporal chaos occurs. In order to stabilize the equilibrium solutions of the systems, at first, we reduce the PDEs to discrete-time systems using the met...

We present a noncausal framework for model-based feedback stabilization of a large class of spatially developing boundary-layer 'ow systems. The systems considered are (approximately) parabolic in the spatial coordinate x. This facilitates the application of a range of established feedback control theories which are based on the solution of di6erential Riccati equations which march over a 8nite...

Linear stability of an incompressible triple-deck flow over a wall roughness is considered for disturbances of high frequency. The wall roughness consists of two relatively short obstacles placed far apart on an otherwise flat surface. It is shown that the flow is unstable to feedback or global mode disturbances. The feedback loop is formed by algebraically decaying disturbances propagating ups...

We consider boundary stabilization for one– dimensional systems of linear hyperbolic partial differential equations with relaxation structure. Such equations appear in many applications. By combining weighted Lyapunov functions, the structure is used to derive new stabilization results. The result is illustrated with an application to boundary stabilization of water flows in open canals.

In this paper, we investigate the effect of time delays in boundary or internal feedback stabilization of the multidimensional Schrödinger equation. In both cases, under suitable assumptions, we establish sufficient conditions on the delay term that guarantee the exponential stability of the solution. These results are obtained by using suitable energy functionals and some observability estimates.

Tracking of a reference signal (assumed bounded with essentially bounded derivative) is considered in a context of a class of nonlinear systems, with output y, described by functional differential equations (a generalization of the class of linear minimum-phase systems with positive high-frequency gain). The primary control objective is tracking with prescribed accuracy: given λ > 0 (arbitraril...

Future power systems are expected to have distributed energy resources (DERs). A price-based operation (PBO), where dynamic prices are used as the control signal, can be an alternative scheme to address challenging operational issues in the future power systems. In this paper, a decentralized framework for optimal PBO using a feedback control mechanism is proposed to determine the nodal prices ...