1,314 research outputs found
The Palomar Transient Factory: System Overview, Performance and First Results
The Palomar Transient Factory (PTF) is a fully-automated, wide-field survey
aimed at a systematic exploration of the optical transient sky. The transient
survey is performed using a new 8.1 square degree camera installed on the
48-inch Samuel Oschin telescope at Palomar Observatory; colors and light curves
for detected transients are obtained with the automated Palomar 60-inch
telescope. PTF uses eighty percent of the 1.2-m and fifty percent of the 1.5-m
telescope time. With an exposure of 60-s the survey reaches a depth of
approximately 21.3 in g' and 20.6 in R (5 sigma, median seeing). Four major
experiments are planned for the five-year project: 1) a 5-day cadence supernova
search; 2) a rapid transient search with cadences between 90 seconds and 1 day;
3) a search for eclipsing binaries and transiting planets in Orion; and 4) a
3-pi sr deep H-alpha survey. PTF provides automatic, realtime transient
classification and follow up, as well as a database including every source
detected in each frame. This paper summarizes the PTF project, including
several months of on-sky performance tests of the new survey camera, the
observing plans and the data reduction strategy. We conclude by detailing the
first 51 PTF optical transient detections, found in commissioning data.Comment: 12 pages, 11 figures, 3 tables, submitted to PAS
Cyber-Physical Systems and Smart Cities in India: Opportunities, Issues, and Challenges
A large section of the population around the globe is migrating towards urban settlements.
Nations are working toward smart city projects to provide a better wellbeing for the inhabitants.
Cyber-physical systems are at the core of the smart city setups. They are used in almost every system
component within a smart city ecosystem. This paper attempts to discuss the key components
and issues involved in transforming conventional cities into smart cities with a special focus on
cyber-physical systems in the Indian context. The paper primarily focuses on the infrastructural
facilities and technical knowhow to smartly convert classical cities that were built haphazardly due
to overpopulation and ill planning into smart cities. It further discusses cyber-physical systems as
a core component of smart city setups, highlighting the related security issues. The opportunities
for businesses, governments, inhabitants, and other stakeholders in a smart city ecosystem in the
Indian context are also discussed. Finally, it highlights the issues and challenges concerning technical,
financial, and other social and infrastructural bottlenecks in the way of realizing smart city concepts
along with future research directions
On Throughput for UAV Relay Assisted for Use in Disaster Communications
In this paper, the system performance of an energy harvesting (EH) unmanned aerial vehicle (UAV) system for use in disasters was investigated. The communication protocol was divided into two phases. In the first phase, a UAV relay (UR) harvested energy from a power beacon (PB). In the second phase, a base station (BS) transmitted the signal to the UR using non-orthogonal multiple access (NOMA); then, the UR used its harvested energy from the first phase to transfer the signal to two sensor clusters, i.e., low-priority and high-priority clusters, via the decode-and-forward (DF) technique. A closed-form expression for the throughput of the cluster heads of these clusters was derived to analyze the system performance. Monte Carlo simulations were employed to verify our approach
Big Data and the Internet of Things
Advances in sensing and computing capabilities are making it possible to
embed increasing computing power in small devices. This has enabled the sensing
devices not just to passively capture data at very high resolution but also to
take sophisticated actions in response. Combined with advances in
communication, this is resulting in an ecosystem of highly interconnected
devices referred to as the Internet of Things - IoT. In conjunction, the
advances in machine learning have allowed building models on this ever
increasing amounts of data. Consequently, devices all the way from heavy assets
such as aircraft engines to wearables such as health monitors can all now not
only generate massive amounts of data but can draw back on aggregate analytics
to "improve" their performance over time. Big data analytics has been
identified as a key enabler for the IoT. In this chapter, we discuss various
avenues of the IoT where big data analytics either is already making a
significant impact or is on the cusp of doing so. We also discuss social
implications and areas of concern.Comment: 33 pages. draft of upcoming book chapter in Japkowicz and Stefanowski
(eds.) Big Data Analysis: New algorithms for a new society, Springer Series
on Studies in Big Data, to appea
Harbingers of Exotic Transients: The Electromagnetic Follow-up of Gravitational-wave Transients & Transient Rates
Gravitational waves (GWs) provide a unique view of the universe. They directly probe the extreme gravity and extreme matter of compact objects like black holes (BHs) and neutron stars (NSs) which is not always possible from traditional electromagnetic (EM) wave astronomy. The cataclysmic coalescence of compact object binaries is one of the loudest individual sources of GWs that can be detected by the Laser Interferometer Gravitational wave Observatory (LIGO) and the Virgo Observatory. If one of the component is a NS, there is a possibility that the merger is bright in the EM spectrum. The relativistic astrophysics could launch a short gamma-ray burst, the radioactivity in the neutron rich ejecta could power a rapidly decaying optical transient called a kilonova. Hence, it is possible to jointly observe the same source via multiple messengers. It is this prospect of multi-messenger astronomy using GWs that is of great interest due to the rich science that can be extracted from such joint observations. In this thesis, I present the details of my work with the LIGO Scientific Collaboration and Virgo Collaboration in the context of multi-messenger astronomy. I also report my work on the time-domain astronomy front in the development of an observing strategy for the Zwicky Transient Facility (ZTF), and characterizing the detection efficiency of the intermediate Palomar Transient Factory (iPTF)
On Learning based Parameter Calibration and Ramp Metering of freeway Traffic Systems
Ph.DDOCTOR OF PHILOSOPH
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