This paper discusses a method of modeling individual differences in cognitive control by developing models that differ in control structure. Such a strategy for modeling behavior is necessitated when tasks are complex and individual differences in performance vary on many measures of performance. For these tasks, merely adjusting a parameter to fit various groups of subjects may be impractical ...

In the engineering database system, multiple versions of a design including engineering drawings should be managed efficiently. The paper proposes an extended spatial data structure for efficient management of multiversion engineering drawings. The R-tree is adapted as a basic data structure. The efficient mechanism to manage the difference between drawings is introduced to the R-tree to elimin...

I present a model of expert comprehension performance for 2 × 2 “interaction” graphs typically used to present data from two-way factorial research designs. Developed using the ACT-R cognitive architecture, the model simulates the cognitive and perceptual operations involved in interpreting interaction graphs and provides a detailed characterisation of the information extracted from the diagram...

Presents an interview conducted with Maruthi R. Akella.

The nature and types of information in a dynamic battle eld environment ranges from georeferenced satellite images and terrain elevation to maps containing terrain features like roads, enemy unit deployment, activities and targets to spatio-temporal objects like logistic, tactical, and collection management plans. E cient processing of queries over such objects in a database requires support of...

There exist many access control models in the literature, and several models are emerging each year. Yet, there is no formal taxonomy to compare the administrative features of these models. We propose a novel formalism to compare access control administration models based on their expressivity in a) administrative decentralization and b) conflict resolution. The contribution is a taxonomy by wh...

We investigate two well-known basic optimal control problems for chemotherapeutic cancer treatment modified by introducing a timedependent “resistance factor”. This factor should be responsible for the effect of the drug resistance of tumor cells on the dynamical growth for the tumor. Both optimal control problems have common pointwise but different integral constraints on the control. We show ...

2. Direct Adaptive Control of Scalar Plant. Let us begin with a simple scalar adaptive system, ẋp(t) = apxp(t) + kpu(t) (1) where xp(t) ∈ R is the plant state, u(t) ∈ R is the control input, ap ∈ R is an unknown scalar and only the sign of kp ∈ R is known. For the direct adaptive controller we choose a reference model as ẋm(t) = amxm(t) + kmr(t)− l(x(t)− xm(t)). (2) All of the parameter above a...