An empirical study on evolutionary feature selection in intelligent tutors for learning concept detection

Concept map mining (CMM) has emerged as a new research area with recent developments in computational intelligence in educational technology. CMM includes the following steps: extracting the learning concepts from educational content, specifying relations among them, and generating a concept map as a result. The purpose of this study was to develop a mechanism using data mining technique to determine the features that characterize a learning concept extracted automatically from a single educational text. The 3 major features that distinguish the real learning concepts from other sequences of strings are detected by using a hybrid system of a feed‐forward neural network and some evolutionary algorithms. Ant colony optimization and genetic algorithm and particle swarm optimization are used as a binary feature selection method. In addition, the aforementioned methods are hybridized to get better accuracy and precision. The performance comparisons with two different state‐of‐the‐art algorithms have been made from the viewpoint of a typical classification problem.     

Realisation of nth-order current transfer function employing ECCIIs and application examples

In this article, a universal nth-order current-mode filter employing electronically tunable second-generation current conveyors (ECCIIs) and grounded passive elements is proposed. As the current gain of the ECCII can be controlled electronically by adjusting the ratio of its DC bias currents, it is possible to tune all the coefficients of the transfer function independently. SPICE simulation results using TSMC 0.35 μm CMOS process model are included to verify the theory. Furthermore, a design example of a fourth-order video band filter is given to illustrate the application of the introduced topology in analog circuit design.     

Embankment Dam on Liquefiable Foundation—Dynamic Behavior and Densification Remediation

Earthquake-induced liquefaction is a major concern for embankment dam safety. Many liquefaction-induced earth embankment failures or near failures have been reported around the world during various earthquakes. Such embankment damages were particularly destructive when the underlying saturated granular soils liquefied, resulting in cracking, settlement, lateral spreading, and slumping of the embankment. Through a series of four highly instrumented geotechnical centrifuge model tests, seismic behavior of a zoned embankment dam with saturated sandy soil foundation was studied under moderate earthquake conditions. The beneficial effects of foundation densification were investigated. Valuable insights into the dynamic behavior of the employed embankment–foundation systems are provided. Test results suggest that there may be an optimum depth of densification treatment beneath an earth dam beyond which the reduction of the earthquake-induced deformations are relatively minor and that relatively small and isolated zones (e.g., at depth) of loose material within a densified volume of soil may not impair the overall effectiveness of treatment and do not necessarily result in damaging displacements.     

Effect of transverse shear strains on plates resting on elastic foundation using modified Vlasov model

A four-noded quadrilateral (PBQ4) and an eight-noded quadrilateral (PBQ8) plate bending element based on Mindlin plate theory are adopted for the analysis of thin and thick plates resting on elastic foundation using modified Vlasov model. The terms of vertical deflection stiffness matrix and shear deformation stiffness matrix of the subsoil are evaluated using finite element method, and presented in explicit forms. Selective reduced integration technique is used in addition to full integration technique for both the types of the elements to avoid shear-locking problem that occurs under the thin plate limit. It has been demonstrated that the performance of the eight-noded quadrilateral element is excellent for thin and thick plates on elastic foundation when selective-reduced integration technique is used. General conclusion can be drawn from the results that the effect of the shear strain on the behavior of the plate resting on subsoil is always quite small for free plates compare to the supported ones.