8491719
DIAR: A Dynamic Interference Aware Routing Protocol for IEEE 802.11-Based Mobile Ad Hoc Networks
A fundamental issue impacting the performance of mobile ad hoc networks is the wireless interference among neighboring nodes. In this paper, we derive an interference aware metric NAVC based on the information collected from the IEEE 802.11 Medium Access Control (MAC) layer. We then propose a novel Dynamic Interference Aware Routing protocol (DIAR) building on NAVC and AODV [3]. Both mathematical analysis and experimental study indicate that NAVC can effectively predict available bandwidth and delay. Simulation results indicate that the overall system performance can be improved by DIAR compared to AODV.
16220987
The Effective Radius Model for Multi-hop Wireless Networks
In this paper, we introduce a novel model, termed as Effective Radius (ER), to calculate the expected number of t-hop neighbors in a multi-hop wireless network with a uniform node distribution on the average. This ER model is an analytical tool that recursively computes a t-hop effective radius for t=2, 3, ⋯. The total number of nodes covered by the disk with a t-hop effective radius equals to the expected number of nodes reachable through at most t hops in the original physical topology. We conduct extensive simulation studies to validate our model and the results demonstrate that the ER model is accurate and can be adaptive to different deployment scenarios. Our findings have interesting applications to the design and evaluation of multi-hop wireless networks.
15762592
Investigating the viability of mental models held by novice programmers
This paper describes an investigation into the viability of mental models used by novice programmers at the end of a first year Java programming course. The qualitative findings identify the range of mental models of value and reference assignment held by the participants. The quantitative analysis reveals that approximately one third of students held non-viable mental models of value assignment and only 17% of students held a viable mental model of reference assignment. Further, in terms of a comparison between the participants' mental models and their performance in in-course assessments and final examination, it was found that students with viable mental models performed significantly better than those with non-viable models. These findings are used to propose a more "constructivist" approach to teaching programming based on the integration of "cognitive conflict" and program visualisation.
12484784
Local Independent Factorization of Natural Scenes
In this paper, we study sparse representation of large-size natural scenes via local spatial dependency decomposition. We propose a local independent factorization model of natural scenes and develop a learning algorithm for adaptation of the synaptic weights. We investigate the dependency of neighboring location of the natural scene patches and derive learning algorithm to train the visual neural network. Some numerical experiments on natural scenes are performed to show the sparse representation of the visual sensory information.
14732000
Smallest Color-Spanning Objects
Motivated by questions in location planning, we show for a set of colored point sites in the plane how to compute the smallest-- by perimeter or area--axis-parallel rectangle and the narrowest strip enclosing at least one site of each color.
717524
Electronic marketplaces in Hong Kong's trading industry
Electronic marketplaces are important because of their potential to change industry structure, for example, by eliminating or altering the role of traditional intermediaries, leading to consolidation of fragmented industries or fragmentation of consolidated ones. Not solely a western phenomenon, there has been considerable electronic marketplace activity in Asia. Because supply chains in Asia are more fragmented than those in the US, many observers expect greater potential for electronic marketplace benefits, and hence adoption and impacts, in Asia. Still in their startup phase, it is too soon to expect to see evidence of industry structure change attributable to electronic marketplaces-such as declining prices for goods, reduction in the number of trading firms through bankruptcies or mergers and acquisitions, or systematic changes in the ways buyers conduct international sourcing. However, it is not too soon to start trying to understand the ways in which industry structure might change by looking at what the electronic marketplaces are trying to do. In particular, we are concerned with three theoretically motivated issues: 1) how well Asian marketplaces match theoretical characteristics believed likely to lead to changes in industry structure, 2) the electronic marketplaces' avowed strategic intents, and 3) their resources for success.
12744752
A method for repairing the inconsistency of fuzzy preference relations
This paper investigates the inconsistency problems of preference information about alternatives expressed as a fuzzy preference relation by a decision maker. An analysis method is presented to identify the inconsistency and weak transitivity of a fuzzy preference relation and to repair its inconsistency to reach weak transitivity. First, several definitions are given on additive consistency, inconsistency and weak transitivity of a fuzzy preference relation. Next, two methods derived from graph theory are presented to judge whether a fuzzy preference relation has weak transitivity or not. Then, an algorithm is developed to repair an inconsistent fuzzy preference relation and to make it become one with weak transitivity, via a synthesis matrix which reflects the relationship between the fuzzy preference relation with additive consistency and the initial one given by a decision maker. A convergence theorem is also given for the algorithm. Lastly, two numerical examples are shown to illustrate the proposed method.