The global (absolute) stability of nonlinear systems with negative
feedbacks and positive descriptor linear parts is addressed. Transfer
matrices of positive descriptor linear systems are analyzed. The
characteristics u = f(e) of the
nonlinear parts satisfy the condition
k₁e
≤ f(e) ≤ k₂e
for some positive k₁, k₂.
It is shown that the nonlinear feedback systems are globally
asymptotically stable if the Nyquist plots of the positive descriptor
linear parts are located in the right-hand side of the circles (–¹/k₁,
–¹/k₂).
The observation inflation effect consists in the fact that observing an action being performed can create false memories that this action has actually been performed by the observer. The present study examined the relationship between this effect and interrogative suggestibility. A procedure based on the Gudjonsson Suggestibility Scale was used to assess two kinds of suggestibility: the tendency to yield to suggestive questions (Yield) and the tendency to change answers after feedback (Shift). The participants first watched a film depicting a woman performing simple activities and performed various activities themselves during the film. In order to determine whether the observation inflation effect occurred, the participants performed a source-monitoring test. The observation inflation effect was replicated. Observation inflation correlated positively with Yield but not with Shift. This pattern of results can be explained by the fact these two indicators are different aspects of interrogative suggestibility. Shift is more related to social influence, while Yield is more cognitive in its nature.
The global stability of discrete-time nonlinear systems with descriptor positive linear parts and positive scalar feedbacks is addressed. Sufficient conditions for the global stability of standard and fractional nonlinear systems are established. The effectiveness of these conditions is illustrated on numerical examples.
It is shown that in uncontrollable linear system ẋ = Ax + Bu it is possible to assign arbitrarily the eigenvalues of the closed-loop system with state feedbacks u = Kx, K ∈ ℜn⨉m if rank [A B] = n. The design procedure consists in two steps. In the step 1 a nonsingular matrix M ∈ ℜn⨉m is chosen so that the pair (MA,MB) is controllable. In step 2 the feedback matrix K is chosen so that the closed-loop matrix Ac = A − BK has the desired eigenvalues. The procedure is illustrated by simple example.
Despite the large number of studies conducted on teachers’ oral corrective feedback, the findings of these studies have been mainly limited to cognitive orientations rooted in experimental designs and the verbal discourse of the teacher as the main object of inquiry. Considering teachers’ affective concerns regarding their corrective feedback and the shift from negative psychology to positive psychology in the field of second/foreign language teaching as well as the entirety of the teacher’s corrective repertoire, in this case study, we aimed to explore the enjoyment building capacity of a teacher’s multimodal corrective feedback in a university general English course. We video-recorded the teacher’s multimodal corrective feedback including verbal and nonverbal semiotic resources like gesture, gaze, and posture while observing the learners’ emotional experiences for eight sessions. We also conducted stimulated recall interviews with some learners and collected their written journals about the experiences of enjoyment with regard to the teacher’s multimodal corrective feedback scenarios. The teacher’s multimodal corrective feedback was analyzed through systemic functional multimodal discourse analysis (SF-MDA) and the content of the interview transcripts as well as the written journals were qualitatively analyzed. The findings indicated that the teacher’s inherent multimodality in his corrective feedback broadened the main dimensions of enjoyment by raising the learners’ attention to their errors, heightening their focus on the correct form, and increasing the salience of his corrective feedback. Further arguments regarding the findings are discussed.
In this paper, the issue related to control of the plant with nonconstant parameters is addressed. In order to assure the unchanged response of the system, an adaptive state feedback speed controller for permanent magnet synchronous motor is proposed. The model-reference adaptive system is applied while the Widrow-Hoff rule is used as adjustment mechanism of controller’s coefficients. Necessary modifications related to construction of the cost function and formulas responsible for adjustment of state feedback speed controller’s coefficients are depicted. The impact of adaptation gain, which is the only parameter in proposed adjustment mechanism, on system behaviour is experimentally examined. The discussion about computational resources consumption of the proposed adaptation algorithm and implementation issues is included. The proposed approach is utilized in numerous experimental tests on modern SiC based drive with nonconstant moment of inertia. Comparison between adaptive and nonadaptive control schemes is also shown.
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