Central University of Kerala

About: Central University of Kerala is a education organization based out in Kāsaragod, India. It is known for research contribution in the topics: Population & Catalysis. The organization has 556 authors who have published 881 publications receiving 7474 citations.

Cluster Dependent Classifiers for Online Signature Verification

Abstract: In this paper, the applicability of notion of cluster dependent classifier for online signature verification is investigated. For every writer, by the use of a number of training samples, a representative is selected based on minimum average distance criteria centroid across all the samples of that writer. Later k-means clustering algorithm is employed to cluster the writers based on the chosen representatives. To select a suitable classifier for a writer, the equal error rate EER is estimated using each of the classifier for every writer in a cluster. The classifier which gives the lowest EER for a writer is selected to be the suitable classifier for that writer. Once the classifier for each writer in a cluster is decided, the classifier which has been selected for a maximum number of writers in that cluster is decided to be the classifier for all writers of that cluster. During verification, the authenticity of the query signature is decided using the same classifier which has been selected for the cluster to which the claimed writer belongs. In comparison with the existing works on online signature verification, which use a common classifier for all writers during verification, our work is based on the usage of a classifier which is cluster dependent. On the other hand our intuition is to recommend to use a same classifier for all and only those writers who have some common characteristics and to use different classifiers for writers of different characteristics. To demonstrate the efficacy of our model, extensive experiments are carried out on the MCYT online signature dataset DB1 consisting signatures of 100 individuals. The outcome of the experiments being indicative of increased performance with the adaption of cluster dependent classifier seems to open up a new avenue for further investigation on a reasonably large dataset.

Theoretical and computational study of instability in streaming negative ion plasma under static magnetic field

Abstract: The instability and electrostatic wave modes generation in a cold negative ion plasma which streams across a static magnetic field has been analysed by fluid dynamical model and computer simulation technique. In the theoretical approach, we observed different kinds of acoustic modes and cyclotron modes at an oblique angle to the static magnetic field. At some critical wave number, the positive and negative ion acoustic modes split up into two, fast and slow waves. The value of critical wave numbers and wave growth rates depends on the plasma streaming velocity, electron concentration in the system, and magnetic field intensity. In the presence of high intense external magnetic fields, we observed a wave coupling between different electrostatic modes. With the help of computer simulation performed by the Particle In Cell method, we confirmed the presence of theoretically proposed wave modes and studied the evolution of instability in detail.

Copepod crustaceans parasitizing marine fish of the Kerala coast, India

Abstract: с июля 2013 г. по февраль 2019 г. Выявлено сто видов копепод, относящихся к 31 роду восьми семейств, обитающих на 85 видах рыб, относящихся к 65 родами 34 семейств. Копеподы отряда Siphonostomatoida — преобладающие паразиты, относящиеся к пяти семействам: Caligidae, Lernaeopodidae, Lernanthropidae, Pennellidae и Pseudocycnidae. Семейства Caligidae и Lernanthropidae — наиболее разнообразные семейства, каждое из которых включает 29 видов и относящихся к восьми и пяти родам, соответственно. Роды Caligus и Lernanthropus, насчитывающие 20 и 21 видов — самые разнообразные рода сифоностоматоидных копепод. Все 26 видов девяти родов поецилостомовых циклопоид относятся к семействам Bomolochidae, Chondracanthidae и Ergasilidae. Большое разнообразие копепод, паразитирующих на рыбах, указывает на необходимость проведение тщательного комплексного исследования разнообразия, специфичности к хозяевам и экологии копепод не только вдоль побережья Кералы, но и у берегов других районов Индии.