Predictive feedback control and Fitts' law

Fitts’ law is a well established empirical formula, known for encapsulating the “speed-accuracy trade-off”. For discrete, manual movements from a starting location to a target, Fitts’ law relates movement duration to the distance moved and target size. The widespread empirical success of the formula is suggestive of underlying principles of human movement control. There have been previous attempts to relate Fitts’ law to engineering-type control hypotheses and it has been shown that the law is exactly consistent with the closed-loop step-response of a time-delayed, first-order system. Assuming only the operation of closed-loop feedback, either continuous or intermittent, this paper asks whether such feedback should be predictive or not predictive to be consistent with Fitts law. Since Fitts’ law is equivalent to a time delay separated from a first-order system, known control theory implies that the controller must be predictive. A predictive controller moves the time-delay outside the feedback loop such that the closed-loop response can be separated into a time delay and rational function whereas a non- predictive controller retains a state delay within feedback loop which is not consistent with Fitts’ law. Using sufficient parameters, a high-order non-predictive controller could approximately reproduce Fitts’ law. However, such high-order, “non-parametric” controllers are essentially empirical in nature, without physical meaning, and therefore are conceptually inferior to the predictive controller. It is a new insight that using closed-loop feedback, prediction is required to physically explain Fitts’ law. The implication is that prediction is an inherent part of the “speed-accuracy trade-off”

The Strategic Role of Human Resources Development in the Management of Organizational Crisis

Together with the global economic crisis, the impact of organizational crises on human capital and its performances has become increasingly obvious. From this perspective, the strategic role of human resources’ development is crucial, being analyzed in this article. It provides the conceptual basis for human resource management practitioners, to understand how to strengthening and developing human potential enables the construction of crisis management skills, manifested at the institutional level.strategic development, human resources, institutional crisis, organizational stress, professional training.

Dichotomous Hamiltonians with Unbounded Entries and Solutions of Riccati Equations

An operator Riccati equation from systems theory is considered in the case that all entries of the associated Hamiltonian are unbounded. Using a certain dichotomy property of the Hamiltonian and its symmetry with respect to two different indefinite inner products, we prove the existence of nonnegative and nonpositive solutions of the Riccati equation. Moreover, conditions for the boundedness and uniqueness of these solutions are established.Comment: 31 pages, 3 figures; proof of uniqueness of solutions added; to appear in Journal of Evolution Equation

Weak topologies for Carath\'eodory differential equations. Continuous dependence, exponential Dichotomy and attractors

We introduce new weak topologies and spaces of Carath\'eodory functions where the solutions of the ordinary differential equations depend continuously on the initial data and vector fields. The induced local skew-product flow is proved to be continuous, and a notion of linearized skew-product flow is provided. Two applications are shown. First, the propagation of the exponential dichotomy over the trajectories of the linearized skew-product flow and the structure of the dichotomy or Sacker-Sell spectrum. Second, how particular bounded absorbing sets for the process defined by a Carath\'eodory vector field $f$ provide bounded pullback attractors for the processes with vector fields in the alpha-limit set, the omega-limit set or the whole hull of $f$. Conditions for the existence of a pullback or a global attractor for the skew-product semiflow, as well as application examples are also given.Comment: 34 page

High Inflation and the Nominal Anchors of an Open Economy

A high inflation process is usually due to a real imbalance and cannot be cured without a correction of real furamenta1s. Yet it can be characterized as a quasi-stable nominal process which gets divorced from the real system in what Patinkin could call a valid classical dichotomy. This paper extends the existing seignorage model approach to multiple inflationary equilibria by rationalizing a high inflation equilibrium as well as its stability as the outcomes of sub-optimization by a 'soft' government. It considers the advantages as well as the weaknesses of using the exchange rate as the key nominal anchor in the various stages of stabilization to low (or zero) inflation. Finally the rationale for using multiple nominal anchors is also discussed. Applications of the theoretical arguments are illustrated from recent high inflation and stabilization experience.