9,574 research outputs found
Granular approach to adaptivity in problem-based learning
Constructivist approach to learning has been around for quite some time. The constructivist theory has resulted in the development of a wide variety of learning environments, however the problem-based learning (PBL) environment is one of the most ideal and most popular area that implements the constructivism theory. PBL is an attractive approach to foster learner's critical problem solving and self-directed learning skills. However, it is difficult to implement effective PBL environments. A majority of existing PBL environments suffers from the fact that the students easily get inundated by the fine granularity of the problems and loose focus of overall aims of the learning process. This project has introduced student adaptivity technology into PBL environments to improve the effectiveness and efficiency of the learning process. To demonstrate the idea of PBL with student adaptivity, a web-based prototype is implemented in Process Costing, within the field of Accounting. Based on the architecture of the web-based intelligent educational systems, the problem base module is introduced. The basic architecture of the system is a typical three-tier, client-server structure. The client tier has the presentation interfaces that are implemented as HTML frames and run in a web browser. The application programs for performing adaptation, which were developed using PHP, reside in the middle layer, and communicate directly with the backend database: problem base, knowledge base that is the third tier. The web server as the communication channel also resides in the middle tier. With the system, students work on the real world costing calculation problems, and the system evaluates students' performance results on the problems to provide adaptation to the students. In summary, this project has successfully introduced the student adaptivity into the PBL environment. The strategies used in this thesis can be applied into the pure PBL educational systems to improve their adaptation capability
A Toy Model for Testing Finite Element Methods to Simulate Extreme-Mass-Ratio Binary Systems
Extreme mass ratio binary systems, binaries involving stellar mass objects
orbiting massive black holes, are considered to be a primary source of
gravitational radiation to be detected by the space-based interferometer LISA.
The numerical modelling of these binary systems is extremely challenging
because the scales involved expand over several orders of magnitude. One needs
to handle large wavelength scales comparable to the size of the massive black
hole and, at the same time, to resolve the scales in the vicinity of the small
companion where radiation reaction effects play a crucial role. Adaptive finite
element methods, in which quantitative control of errors is achieved
automatically by finite element mesh adaptivity based on posteriori error
estimation, are a natural choice that has great potential for achieving the
high level of adaptivity required in these simulations. To demonstrate this, we
present the results of simulations of a toy model, consisting of a point-like
source orbiting a black hole under the action of a scalar gravitational field.Comment: 29 pages, 37 figures. RevTeX 4.0. Minor changes to match the
published versio
About Adaptive Coding on Countable Alphabets: Max-Stable Envelope Classes
In this paper, we study the problem of lossless universal source coding for
stationary memoryless sources on countably infinite alphabets. This task is
generally not achievable without restricting the class of sources over which
universality is desired. Building on our prior work, we propose natural
families of sources characterized by a common dominating envelope. We
particularly emphasize the notion of adaptivity, which is the ability to
perform as well as an oracle knowing the envelope, without actually knowing it.
This is closely related to the notion of hierarchical universal source coding,
but with the important difference that families of envelope classes are not
discretely indexed and not necessarily nested.
Our contribution is to extend the classes of envelopes over which adaptive
universal source coding is possible, namely by including max-stable
(heavy-tailed) envelopes which are excellent models in many applications, such
as natural language modeling. We derive a minimax lower bound on the redundancy
of any code on such envelope classes, including an oracle that knows the
envelope. We then propose a constructive code that does not use knowledge of
the envelope. The code is computationally efficient and is structured to use an
{E}xpanding {T}hreshold for {A}uto-{C}ensoring, and we therefore dub it the
\textsc{ETAC}-code. We prove that the \textsc{ETAC}-code achieves the lower
bound on the minimax redundancy within a factor logarithmic in the sequence
length, and can be therefore qualified as a near-adaptive code over families of
heavy-tailed envelopes. For finite and light-tailed envelopes the penalty is
even less, and the same code follows closely previous results that explicitly
made the light-tailed assumption. Our technical results are founded on methods
from regular variation theory and concentration of measure
Adaptive Wireless Networking
This paper presents the Adaptive Wireless Networking (AWGN) project. The project aims to develop methods and technologies that can be used to design efficient adaptable and reconfigurable mobile terminals for future wireless communication systems. An overview of the activities in the project is given. Furthermore our vision on adaptivity in wireless communications and suggestions for future activities are presented
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