Delhi Technological University

About: Delhi Technological University is a education organization based out in New Delhi, India. It is known for research contribution in the topics: Computer science & Control theory. The organization has 4427 authors who have published 6761 publications receiving 71035 citations. The organization is also known as: Delhi College of Engineering & DTU.

Emotion analysis of Twitter using opinion mining

Abstract: With the rise in use of micro-blogging sites like Twitter, people are able to express and share their opinions with each other on a common platform. Currently all work in opinion mining research has quantified & assessed the expression of opinion as positive, negative or neutral values, we intend to categorize the opinion on the basis of five emotions, namely Happiness, Anger, Fear, Sadness & Disgust, which have been globally accepted & defined in human psychology. This paper presents a method to assess these identified types of emotions in a tweet using opinion mining. A two-step approach is proposed, where firstly, to identify the sentiment; we extract the opinion words (a combination of the adjectives along with the verbs and adverbs) in the tweets and subsequently use a novel algorithm to find the emotion values of opinion words. The initial results show that it is a motivating technique, which may find potential applications in business intelligence, government policy making, amongst others.

Luminescence properties and exciton dynamics of core–multi-shell semiconductor quantum dots leading to QLEDs

Abstract: In this study, we grew CdSe core quantum dots (QDs) along with CdSe/ZnS/ZnS and CdSe/CdS/CdS core-multi-shell semiconductor QDs via successive ionic layer adsorption and reaction. The effects of the shell layers on the optical properties and exciton dynamics of the QDs were examined using steady-state and time-resolved measurements together with transient absorption (TA). The photoluminescence (PL) intensity and quantum yield (QY) of the synthesized QDs were enhanced by shell growth. The QY of the QDs increased from 23% to 41% with shell growth due to the decrease in nonradiative recombination sites, which was attributed to surface passivation by the shell layer. The average PL lifetime decreased with shell growth. This effect might be related to the reduction of electron and hole densities on the QD surfaces. The TA spectra show bleaching and photoinduced absorption, corresponding to the state-filling effect and trap states, respectively. The findings are essential for understanding the growth and applications of core-multi-shell QDs.