Sep 12th, 2007| 04:31 pm | Posted by hlee
From arxiv/astro-ph:0709.1359,
A robust morphological classification of high-redshift galaxies using support vector machines on seeing limited images. I Method description by M. Huertas-Company et al.
Machine learning and statistical learning become more and more popular in astronomy. Artificial Neural Network (ANN) and Support Vector Machine (SVM) are hardly missed when classifying on massive survey data is the objective. The authors provide a gentle tutorial on SVM for galactic morphological classification. Their source code GALSVM is linked for the interested readers.
Continue reading ‘[ArXiv] SVM and galaxy morphological classification, Sept. 10, 2007’ »
Sep 4th, 2007| 10:55 pm | Posted by hlee
From arxiv/astro-ph:0708.4274v1
Comparison of decision tree methods for finding active objects by Y. Zhao and Y. Zhang
The authors (astronomers) introduced and summarized various decision three methods (REPTree, Random Tree, Decision Stump, Random Forest, J48, NBTree, and AdTree) to the astronomical community.
Continue reading ‘[ArXiv] Decision Tree, Aug. 31, 2007’ »
Jul 2nd, 2007| 06:07 pm | Posted by hlee
From arXiv/astro-ph:0706.4484
Spectroscopic Surveys: Present by Yip. C. overviews recent spectroscopic sky surveys and spectral analysis techniques toward Virtual Observatories (VO). In addition that spectroscopic redshift measures increase like Moore’s law, the surveys tend to go deeper and aim completeness. Mainly elliptical galaxy formation has been studied due to more abundance compared to spirals and the galactic bimodality in color-color or color-magnitude diagrams is the result of the gas-rich mergers by blue mergers forming the red sequence. Principal component analysis has incorporated ratios of emission line-strengths for classifying Type-II AGN and star forming galaxies. LyЮБ identifies high z quasars and other spectral patterns over z reveal the history of the early universe and the characteristics of quasars. Also, the recent discovery of 10 satellites to the Milky Way is mentioned.
Continue reading ‘[ArXiv] Spectroscopic Survey, June 29, 2007’ »
Tags:
bimodality,
chi-square minimization,
Classification,
CMD,
Estimation,
machine learning,
massive data,
model based,
PCA,
spectral analysis,
spectroscopic,
survey,
VO Category:
arXiv,
Astro,
Bayesian,
Data Processing,
Fitting,
Frequentist,
Methods,
Spectral |
Comment
Jun 25th, 2007| 01:27 pm | Posted by hlee
One of the papers from arxiv/astro-ph discusses kernel regression and model selection to determine photometric redshifts astro-ph/0706.2704. This paper presents their studies on choosing bandwidth of kernels via 10 fold cross-validation, choosing appropriate models from various combination of input parameters through estimating root mean square error and AIC, and evaluating their kernel regression to other regression and classification methods with root mean square errors from literature survey. They made a conclusion of flexibility in kernel regression particularly for data at high z.
Continue reading ‘[ArXiv] Kernel Regression, June 20, 2007’ »
Tags:
AIC,
BIC,
Classification,
cross-validation,
kernel,
photometric redshifts,
regression,
SDSS Category:
arXiv,
Frequentist,
Galaxies,
Stat |
Comment