Journal:Informatica
Volume 26, Issue 2 (2015), pp. 221–240
Abstract
Abstract
Nowadays the web can serve as a perfect technological environment for personalized learning which is suggested by educators and based on interactive learning objects. While a range of technological solutions for the development of integrated e-learning environments already exists, the most appropriate solutions require further improvement of the implementation of novel learning objects, unification of standardization and integration of learning environments, based on semantic web services that are still in the early stages of development. The aim of the research is to create a model for the development of semantic learning objects, connect it with the architecture of the educational system for semantic learning object design and to present the experimental part of the model’s impact on the course design process. The paper presents the research with the main question on how to improve the e-learning course with semantic learning objects by exploring the application of learning object design approaches, usability, performing modern training facilities and the learning object design model based on semantic web technologies.
Journal:Informatica
Volume 9, Issue 3 (1998), pp. 259–278
Abstract
This note presents an indirect adaptive control scheme applicable to nominally controllable non-necessarily inversely stable first-order continuous linear time-invariant systems with unmodelled dynamics. The control objective is to achieve a bounded tracking-error between the system output and a reference signal. A least-squares algorithm with normalization is used to estimate the plant parameters by using two additional design tools, namely: 1) a modification of the parameter estimates and 2) a relative adaptation dead-zone. The modification is based on the properties of the inverse of the least-squares covariance matrix and it uses an hysteresis switching function. In this way, the non-singularity of the controllability matrix of the estimated model of the plant is ensured. The relative dead-zone is used to turn off the adaptation process when an absolute augmented error is smaller than the value of an available overbounding function of the unmodelled dynamics contribution plus, eventually, bounded noise.
Journal:Informatica
Volume 9, Issue 2 (1998), pp. 173–194
Abstract
This paper addresses the study of the controllability and stability of the equilibrium in economic models which relate the unemployment level to the government expenditure. The interesting cases when the government expenditure is either bounded or a linear function of the national income are specifically considered. The relationships between both variables, namely, unemployment growth level and government expenditure is obtained by considering a Keynesian static model for the national income as well as a differential unemployment-inflation model of Phillips type. Both models are used to derive a new combined one by eliminating the common variable “taxes” which is driven by the investment and government expenditure.
Journal:Informatica
Volume 8, Issue 3 (1997), pp. 345–366
Abstract
Statistical properties are examined for a class of pipelined-block linear time-varying (LTV) and linear time-invariant (LTI) discrete-time systems. Pipelined-block equations are derived, using the general solution of LTV discrete-time system in state space. Afterwards, we analysed the state covariance and output covariance matrices of pipelined-block LTV and LTI discrete-time systems in state space. For this class of pipelined-block realizations expressions are found for calculation of characteristics of the roundoff noise. Finally, scaling in the pipelined LTV discrete-time systems in state space is considered.
Journal:Informatica
Volume 1, Issue 2 (1990), pp. 75–86
Abstract
This paper discusses the inversion of linear periodically time-varying (LPTV) digital filters using the idea of converting the LPTV filter to the block time-invariant filter. Explicit expressions are given to determine the inversion of LPTV filters. Controllability, observability and stability of the inversion of LPTV filters are discussed.