Spherically symmetric trapping horizons, the Misner-Sharp mass and black hole evaporation

Understood in terms of pure states evolving into mixed states, the possibility of information loss in black holes is closely related to the global causal structure of spacetime, as is the existence of event horizons. However, black holes need not be defined by event horizons, and in fact we argue that in order to have a fully unitary evolution for black holes, they should be defined in terms of something else, such as a trapping horizon. The Misner-Sharp mass in spherical symmetry shows very simply how trapping horizons can give rise to black hole thermodynamics, Hawking radiation and singularities. We show how the Misner-Sharp mass can also be used to give insights into the process of collapse and evaporation of locally defined black holes.Comment: 9 pages, 10 figure

Textile Fingerprinting for Dismount Analysis in the Visible, Near, and Shortwave Infrared Domain

The ability to accurately and quickly locate an individual, or a dismount, is useful in a variety of situations and environments. A dismount\u27s characteristics such as their gender, height, weight, build, and ethnicity could be used as discriminating factors. Hyperspectral imaging (HSI) is widely used in efforts to identify materials based on their spectral signatures. More specifically, HSI has been used for skin and clothing classification and detection. The ability to detect textiles (clothing) provides a discriminating factor that can aid in a more comprehensive detection of dismounts. This thesis demonstrates the application of several feature selection methods (i.e., support vector machines with recursive feature reduction, fast correlation based filter) in highly dimensional data collected from a spectroradiometer. The classification of the data is accomplished with the selected features and artificial neural networks. A model for uniquely identifying (fingerprinting) textiles are designed, where color and composition are determined in order to fingerprint a specific textile. An artificial neural network is created based on the knowledge of the textile\u27s color and composition, providing a uniquely identifying fingerprinting of a textile. Results show 100% accuracy for color and composition classification, and 98% accuracy for the overall textile fingerprinting process

The causal structure of dynamical charged black holes

We study the causal structure of dynamical charged black holes, with a sufficient number of massless fields, using numerical simulations. Neglecting Hawking radiation, the inner horizon is a null Cauchy horizon and a curvature singularity due to mass inflation. When we include Hawking radiation, the inner horizon becomes space-like and is separated from the Cauchy horizon, which is parallel to the out-going null direction. Since a charged black hole must eventually transit to a neutral black hole, we studied the neutralization of the black hole and observed that the inner horizon evolves into a space-like singularity, generating a Cauchy horizon which is parallel to the in-going null direction. Since the mass function is finite around the inner horizon, the inner horizon is regular and penetrable in a general relativistic sense. However, since the curvature functions become trans-Planckian, we cannot saymore about the region beyond the inner horizon, and it is natural to say that there is a 'physical' space-like singularity. However, if we assume an exponentially large number of massless scalar fields, our results can be extended beyond the inner horizon. In this case, strong cosmic censorship and black hole complementarity can be violated.Comment: 23 pages, 23 figure

Relationship between temporary emotion of students and performance in learning through comparing facial expression analytics

This paper presents a study on temporary emotion of students and their performance related to learning activities. This paper elucidates different kinds of facial expressions elicited during the activities: quiz and a movie trailer with the help of existing facial expression analyzing applications. The user’s expressions are recorded as video while watching the movie trailer and doing the quiz. The video is processed by different applications which gives the score for different emotions. The results obtained are studied to find which emotion is mostly prevalent among the user in different situations. From this study, it is shown that students experience seemingly different emotions during the activity. The emotions they portrayed were confusion, sadness, anger and neutral. This study explores the use of affective computing for further comprehension of students’ emotion in learning environment

No-boundary measure and preference for large e-foldings in multi-field inflation

The no-boundary wave function of quantum gravity usually assigns only very small probability to long periods of inflation. This was a reason to doubt about the no-boundary wave function to explain the observational universe. We study the no-boundary proposal in the context of multi-field inflation to see whether the number of fields changes the situation. For a simple model, we find that indeed the no-boundary wave function can give higher probability for sufficient inflation, but the number of fields involved has to be very high.Comment: 16 pages, 2 figure

Prototype ultrasonic wayfinder with haptic feedback for an IOT environment

Pervasive computing and the Internet of Things (IoT) have stimulated the development of many new assistive devices. It is possible to incorporate sensors such as acoustic, inductive, capacitive, temperature, humidity, pressure, location, and many more. Haptic feedback provides a person with sensory information through the skin using vibration or force-feedback responses. Commercial organizations have moved very quickly into this design space, particularly Sunu (smart-watch), HandSight (cameras on glove), and others. Arduino and Raspberry Pi are examples of the computing platforms currently in use. Sonar or ultrasonic transducers enable the production of lighter equipment with improved functionalities. Sonar as a means of assistive navigation has been used extensively in maritime environments to detect animals (D'Amico and Pittenger, 2009, Evans and Awbrey, 1988). As an assistive technology, there are projects for the blind which upgrade their walking sticks with an ultrasonic sensor (Amemiya and Sugiyama, 2010). Similar projects have been undertaken worldwide and most devices can only provide one or two designated functions. The size of the completed device is small enough to embed on a shoe, a walking stick, or on a wheelchair. A sonar sensor can detect something less than a meter from an individual user. This study uses a glove to attach a sonar sensor on a Raspberry Pi 0, whereas the Tacit glove (Hoefer, 2011) carries two sonar sensors with an Arduino controller actuating vibrating motors on a glove

Learning Experiences in an International Email Exchange Project

This study examines students’ learning experience in a semester-long email exchange project as a normal class activity between U.S. and Korean social work undergraduate students in fall 2008 and fall 2009. We used a content analysis to analyze the qualitative data of the email content and of the end-of-semester surveys. The study found this email exchange helped students develop cross-cultural understanding; enhance their knowledge of social or social justice issues in both countries; learn the social work profession and its commonalities and differences in both countries; and expand their interest in other countries. This study also suggests ways to modify the project for a better learning experience in the future, based on students’ end-of-semester surveys and instructors’ reflections on the activities