scholarly journals Research on the Application of NS2 Network Simulation Based on Clustering Algorithm

2015 ◽  
Vol 7 (1) ◽  
pp. 1210-1215
Author(s):  
Mao Shengli
2016 ◽  
Author(s):  
Eric Lombaert ◽  
Thomas Guillemaud ◽  
Emeline Deleury

AbstractPopulation genetic methods are widely used to retrace the introduction routes of invasive species. The unsupervised Bayesian clustering algorithm implemented in STRUCTURE is amongst the most frequently use of these methods, but its ability to provide reliable information about introduction routes has never been assessed. We used computer simulations of microsatellite datasets to evaluate the extent to which the clustering results provided by STRUCTURE were misleading for the inference of introduction routes. We focused on the simple case of an invasion scenario involving one native population and two independently introduced populations, because it is the sole scenario with two introduced populations that can be rejected when obtaining a particular clustering with a STRUCTURE analysis at K = 2 (two clusters). Results were classified as “misleading” or “non-misleading”. We then investigated the influence of two demographic parameters (effective size and bottleneck severity) and different numbers of loci on the type and frequency of misleading results. We showed that misleading STRUCTURE results were obtained for 10% of our simulated datasets and at a frequency of up to 37% for some combinations of parameters. Our results highlighted two different categories of misleading output. The first occurs in situations in which the native population has a low level of diversity. In this case, the two introduced populations may be very similar, despite their independent introduction histories. The second category results from convergence issues in STRUCTURE for K = 2, with strong bottleneck severity and/or large numbers of loci resulting in high levels of differentiation between the three populations.


2021 ◽  
Author(s):  
Rakesh Veerabhadrappa ◽  
Imali T. Hettiarachchi ◽  
Samer Hanoun ◽  
Dawei Jia ◽  
Simon G. Hosking ◽  
...  

Abstract Simulation-based training utilising visual displays are common in many defence and civil domains. The performance of individuals in these tasks depends on their ability to employ effective visual strategies. Quantifying the performance of the trainees is vitally important when assessing training effectiveness and developing future training requirements. The approach, attitudes and processes of an individual’s learning varies from one to another. In this light, some visual strategies may be better suited to the dynamics of a task environment than others, the result of which could be observed in the superior performance outcomes of some individuals. In this study, eye gaze data is used to investigate the relationship between performance outcomes and visual strategies. In an attempt to emulate real operational settings, a challenging task environment using multiple targets that had minimal salient features was selected for the study. Eye gaze of participants performing a simulation-based unmanned aerial vehicle (UAV) refuelling task was used to facilitate the investigation. Cross recurrence quantification analysis (CRQA) and Epistemic network analysis (ENA) were employed on eye gaze data to provide spatial-temporal mapping of visual strategies. A CRQA measure of recurrence rate was used to observe participants’ fixation interest on various regions of the task environment. The recurrence behaviours were categorised into cases of visual strategies using an unsupervised clustering algorithm. This article discusses the relationship between the visual strategy cases and performance outcomes to observe which are the most effective. Using the relationship between recurrence rates and performance outcomes, we demonstrate and discuss a gaze-based measure that could objectively quantify performance.


Sign in / Sign up

Export Citation Format

Share Document