Quantifying galactic morphological transformations in the cluster environment

Cervantes‐,Sodi, B.,Park, Changbom,Hernandez, X.,Hwang, Ho Seong Blackwell Publishing Ltd 2011 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.414 No.1

<P><B>ABSTRACT</B></P><P>We study the effects of the cluster environment on galactic morphology by defining a dimensionless angular momentum parameter, λ<SUB>d</SUB>, to obtain a quantitative and objective measure of galaxy type. The use of this physical parameter allows us to take the study of morphological transformations in clusters beyond the measurements of merely qualitative parameters, e.g. spiral/elliptical (S/E) ratios, to a more physical footing. To this end, we employ an extensive Sloan Digital Sky Survey sample (Data Release 7) with galaxies associated with Abell galaxy clusters. The sample contains 121 relaxed Abell clusters and over 51 000 individual galaxies, which guarantees a thorough statistical coverage over a wide range of physical parameters. We find that the median λ<SUB>d</SUB> value tends to decrease as we approach the cluster centre, with different dependences according to the mass of the galaxies and the hosting cluster; low‐ and intermediate‐mass galaxies show a strong dependence, while massive galaxies seem to show, at all radii, low λ<SUB>d</SUB> values. By analysing trends in λ<SUB>d</SUB> as functions of the nearest neighbour environment, clustercentric radius and velocity dispersion of clusters, we can identify clearly the leading physical processes at work. We find that in massive clusters (σ > 700 km s<SUP>−1</SUP>), the interaction with the cluster central region dominates, whilst in smaller clusters galaxy–galaxy interactions are chiefly responsible for driving galactic morphological transformations.</P>

Clues on the origin of galactic angular momentum from looking at galaxy pairs

Cervantes-Sodi, B.,Hernandez, X.,Park, Changbom Blackwell Publishing Ltd 2010 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.402 No.3

<P>ABSTRACT</P><P>We search for correlations between the spins in pairs of spiral galaxies, to study if the angular momentum gain for each galaxy was the result of tidal torques imprinted by the same tidal field. To perform our study we made use of a sample of galaxy pairs identified using the Sloan Digital Sky Survey. We find a weak, but statistically significant correlation between the spin magnitudes of neighbouring galaxies, but no clear alignment between their orientations. We show that events such as interactions with close neighbours play an important role in the value of the spin for the final configuration, as we find that these interactions tend to reduce the value of the λ spin parameter of late-type galaxies considerably, with dependence on the morphology of the neighbour. This implies that the original tidal field for each pair could have been similar, but the redistribution of angular momentum at later stages of evolution is important.</P>

Agent-Based Approach to Distributed Ensemble Learning of Fuzzy ARTMAP Classifiers

Cervantes, L.,Lee, J.-s.,Lee, J. SPRINGER-VERLAG 2007 ICHIT 2012 Vol.4496 No.-

Agent-Based Intelligent Decision Support for the Home Healthcare Environment

Cervantes, L.,Lee, Y.-S.,Yang, H.,Ko, S.-h.,Lee, J. SPRINGER-VERLAG 2007 ICHIT 2012 Vol.4413 No.-

THE GALACTIC SPIN OF AGN GALAXIES

Cervantes-Sodi, Bernardo,Hernandez, X.,Park, Changbom,Choi, Yun-Young IOP Publishing 2011 ASTROPHYSICAL JOURNAL LETTERS - Vol.735 No.1

<P>Using an extensive sample of galaxies selected from the Sloan Digital Sky Survey Data Release 5, we compare the angular momentum distribution of active galactic nuclei (AGNs) with non-AGN hosting late-type galaxies. To this end we characterize galactic spin through the dimensionless angular momentum parameter lambda, which we estimate through simple dynamical considerations. Using a volume-limited sample, we find a considerable difference when comparing the empirical distributions of lambda for AGNs and non-AGN galaxies, the AGNs showing typically low lambda values and associated dispersions, while non-AGNs present higher lambda values and a broader distribution. A more striking difference is found when looking at lambda distributions in thin M-r cuts; while the spin of non-AGN galaxies presents an anticorrelation with M-r, with bright (massive) galaxies having low spins, AGN host galaxies present uniform values of lambda at all magnitudes, a behavior probably imposed by the fact that most late-type AGN galaxies present a narrow range in color, with a typical constant lambda value. We also find that the fraction of AGN hosting galaxies in our sample strongly depends on galactic spin, increasing dramatically for decreasing lambda. For AGN host galaxies, we compute the mass of their supermassive black holes and find that this value tends to be higher for low spin galaxies, even at fixed luminosity, a result that could account, to a certain extent, for the spread on the luminosity-black-hole mass relation.</P>

The spin of spiral galaxies in different environments

Bernardo Cervantes-Sodi 한국천문학회 2010 天文學會報 Vol.35 No.1

Flight Control Design using Incremental Nonlinear Dynamic Inversion with Fixed-lag Smoothing Estimation

Ludeña Cervantes Tito J.,최성환,김병수 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.4

In this study, a flight control design strategy based on incremental nonlinear dynamic inversion (INDI) and smoothing algorithm is presented. The INDI is an enhanced version of the nonlinear dynamic inversion technique with a better robust performance. It reduces the aircraft model dependence via the feedback information of the state derivative, that is, angular acceleration for the aircraft attitude motion (or angular velocity related to the wind axis parameters). However, the state derivatives cannot always be obtained by direct measurement, thus they need to be estimated on-line. Moreover, taking into account that INDI requires one-step delay of state derivative and the fact that the inertial measurement unit (IMU) operates faster than the flight control computer (FCC), there will be additional information that can be used to improve the estimation. Therefore, a fixed-lag smoothing algorithm based on a discrete Kalman filter is proposed for angular velocity and angular acceleration estimation. The smoother utilizes the state variable from the sensor measurement and thus dealing with noise and delay.

Quantifying galactic morphological transformations in the cluster environment

Bernardo Cervantes-Sodi,ChangbomPark,X.Hernandez 한국천문학회 2010 天文學會報 Vol.35 No.2

On dark matter haloes of barred disc galaxies

Bernardo Cervantes Sodi,Cheng Li,Changbom Park,Lixin Wang,Ye Lin 한국천문학회 2014 天文學會報 Vol.39 No.2

한국투자와 중국 산동연해도시발전 세미나 프로그램

Steve Cervantes 동국대학교 경영연구원 2009 경영과 사례연구 Vol.32 No.1

Ironically, throughout most of their history China and Korea were separated from one another. During the Choson dynasty, with the exception of annual and biannual tribute missions to China, contact was almost non-existent. Indeed, there were no two contiguous countries in the world that were as isolated from one another than China and Korea. Contact rapidly increased with China’s participation in the Korean War. After the cease-fire, however, given North Korea’s reclusive policies towards international relations, Chinese-North Korean contact was limited to Chinese technical-assistance missions to North Korea. While no diplomatic relations between China-South Korea, contact was limited. With China accepting an invitation to the 1988 Seoul Olympics, the beginning of a robust relationship between China and Korea began. Thereafter, in 1992, diplomatic relations consummated. Meanwhile major Korean investment had already begun in China’s Shandong region, with Korean Sanyang Food Co. establishing a joint venture with China’s Qingdao Second Food Co. in 1989. For the last twenty years trade and contact between China and Korea have significantly increased. Korean FDI in China is almost 10% of total FDI in China. Chinese comprise of the largest documented and undocumented migrants in Korea. They are also the largest group amongst foreign students at Korean universities. Although outward Chinese FDI has focused more on resource rich countries (Latin America and Africa) recently, when the world economy recoversand there is freer trade, Chinese outward FDI will increase in Korea. Hypothetically, I believe there is a parallel between Chinese and Korean trade relations and Mexican and American ones. During the post Mexican-American War there was indemnity between the two nations. Although they had diplomatic relations, and there were numerous Mexican migrant workers who immigrated to the United States, relations were nevertheless often strained. Like China and Korea, however, given globalization’s inherent creation for supply and demand, trade and diplomatic relations would have to improve. As such, the North American Free Trade Agreement (NAFTA) was signed in 1994 between Canada, Mexico, and the United States. Concerning trade, NAFTA is an economic miracle .In terms of combined purchasing power parity GDP of its members, as of 2007 the trade block is the largest in the world and second largest by nominal GDP comparison. Despite NAFTA’s economic success, there have been numerous trade disputes between Mexico and the United States concerning American farm subsidies and their adverse effects on Mexican farming. However, NAFTA has provided a definitive framework for how FDI and trade are conducted. Put it another way, NAFTA has established rules that all countries have deemed fair and transparent by all three parties. Moreover, numerous trade barriers were brought down With abundant growth in trade and FDI between China and Korea, it is inevitable that more transparent laws governing trade will need to be implemented, so China and Korea can both benefit. Likewise, China and Korea need a definitive framework for how trade and FDI should be conducted. Trade and FDI have grown so abundantly that it is now time to overcome past differences and implement an FTA or trade block between the two countries and perhaps even another country. As such, I believe that Chinese and Korean relations have reached the point where they can create a trade block even more ambitious than NAFTA. Unlike NAFTA, China and Korea’s trade block could include the free flow of migrants without visa restrictions. This would help facilitate the free flow of capital investment between the two countries. By simply easing visa restrictions coupled with China and Korea’s highly skilled labor, a Chinese-Korean trade block would quickly surpass NAFTA’s purchasing power parity and size.