16 research outputs found
A Graph Traversal Based Framework for Sequential Logic Implication with an Application to C-Cycle Redundancy Identification
Coordinated Science Laboratory was formerly known as Control Systems LaboratorySemiconductor Research Corporation / SRC 96-DP-109 and SRC 97-DS-482DARPA / DABT63-95-C-0069Hewlett-Packar
Crowdsourced Adaptive Surveys
Public opinion surveys are vital for informing democratic decision-making,
but responding to rapidly changing information environments and measuring
beliefs within niche communities can be challenging for traditional survey
methods. This paper introduces a crowdsourced adaptive survey methodology
(CSAS) that unites advances in natural language processing and adaptive
algorithms to generate question banks that evolve with user input. The CSAS
method converts open-ended text provided by participants into Likert-style
items and applies a multi-armed bandit algorithm to determine user-provided
questions that should be prioritized in the survey. The method's adaptive
nature allows for the exploration of new survey questions, while imposing
minimal costs in survey length. Applications in the domains of Latino
information environments and issue importance showcase CSAS's ability to
identify claims or issues that might otherwise be difficult to track using
standard approaches. I conclude by discussing the method's potential for
studying topics where participant-generated content might improve our
understanding of public opinion.Comment: 25 pages, 5 figure
Prefix Recoding: a Front-end Compression Technique for Simple Prefix B-trees
This study examines the effect of receding common prefixes of shortest separators and thus extending the alphabet and compressing both the sequence set and the simple prefix B-tree index. The purpose of the study is to investigate the effect on a simple prefix B-tree of receding prefixes with a shorter symbol that maintains collating sequence order.Computing and Information Science
Object-based video representations: shape compression and object segmentation
Object-based video representations are considered to be useful for easing the process of multimedia content production and enhancing user interactivity in multimedia productions. Object-based video presents several new technical challenges, however.
Firstly, as with conventional video representations, compression of the video data is a
requirement. For object-based representations, it is necessary to compress the shape of
each video object as it moves in time. This amounts to the compression of moving
binary images. This is achieved by the use of a technique called context-based
arithmetic encoding. The technique is utilised by applying it to rectangular pixel blocks and as such it is consistent with the standard tools of video compression. The blockbased application also facilitates well the exploitation of temporal redundancy in the sequence of binary shapes. For the first time, context-based arithmetic encoding is used in conjunction with motion compensation to provide inter-frame compression. The method, described in this thesis, has been thoroughly tested throughout the MPEG-4 core experiment process and due to favourable results, it has been adopted as part of the MPEG-4 video standard.
The second challenge lies in the acquisition of the video objects. Under normal conditions, a video sequence is captured as a sequence of frames and there is no inherent information about what objects are in the sequence, not to mention information relating to the shape of each object. Some means for segmenting semantic objects from general video sequences is required. For this purpose, several image analysis tools may be of help and in particular, it is believed that video object tracking algorithms will be important. A new tracking algorithm is developed based on piecewise polynomial motion representations and statistical estimation tools, e.g. the expectationmaximisation method and the minimum description length principle
A contribution to characterizing and calibrating the pointing control system of the SOFIA telescope
SOFIA, the Stratospheric Observatory for Infrared Astronomy, is an airborne observatory that will study the universe in the infrared spectrum. A Boeing 747-SP aircraft will carry a 2.5 m telescope designed to make sensitive infrared measurements of a wide range of astronomical objects. It will fly at and above 12 km, where the telescope collects radiation in the waveÆ length range from 0.3 micrometers to 1.6 millimeters of the electromagnetic spectrum. During flight, a door will be opened to allow clear optical observations from the cavity environment where the telescope is mounted. The telescope pointing control is achieved during science observations by an array of sensors including three imagers, gyroscopes and accelerometers. In addition, throughout alignment and calibration of the telescope assembly, the High-speed Imaging Photometer for Occultation (HIPO) is used as a reference instrument. A theoretical concept has been developed to compensate the perturbations in the airborne environment and to correct them within the attitude control loop. A set of Cartesian reference frames is established to describe and manipulate the orientations of the various subsystems, sensor and pointing orientations.thesi
An Investigation into the Implementation and Performance of Spectrally Shaped Orthogonal Frequency Division Multiplex
Orthogonal Frequency Division Multiplex (OFDM) is a flexible, robust multi-carrier
modulation scheme. The orthogonal spectral shaping and spacing of OFDM sub-carriers
ensure that their spectra can be over-lapped without leading to undesirable inter-carrier
interference. Conventional OFDM systems have non-band limited Sinc(x) shaped subcarrier
spectra. An alternative form of OFDM, referred to hereafter as Spectrally Shaped
OFDM, employs band limited Nyquist shaped sub-carrier spectra. The research described
in this thesis investigates the strengths and weaknesses of Spectrally Shaped OFDM as a
potential modulation scheme for future mobile radio applications.
From this research a novel Digital Signal Processing architecture for modulating and
demodulating Spectrally Shaped OFDM sub-carriers has been derived which exploits the
combination of a complex Discrete Fourier Transform (DFT) and PolyPhase Network
(PPN) filter. This architecture is shown to significantly reduce the minimum number of
computations required per symbol compared to previous designs.
Using a custom coded computer simulation, the effects of varying the key parameters of
the novel architecture's PolyPhase Filter (PPN) filter an the overall system complexity,
spectral performance and system signal-to-distortion have been extensively studied. From
these studies it is shown that compared to similar conventional OFDM systems, Spectrally
Shaped OFDM systems possess superior out-of-band spectral qualities but significantly
worse Peak-to-Average-Power-Ratio (PAPR) envelope performance. lt is also shown that
the absolute value of the end PPN filter coefficients (dependent on the roll-off factor of the
sub-carrier spectral shaping) dictate the system signal-to-distortion ratio when no time-domain
windowing of the PPN filter coefficients is applied. Finally the effects of a both time
and frequency selective fast fading channels on the modulation scheme's uncoded Bit
Error Rate (BER) versus Signal-to-Noise (SNR) performance are simulated. The results
obtained indicate that Spectrally Shaped OFDM is more robust (lower BER) to
frequency-selective fading than time-selective fading
Computer Science Principles with C++
This textbook is intended to be used for a first course in computer science, such as the College Boardâs Advanced Placement course known as AP Computer Science Principles (CSP). This book includes all the topics on the CSP exam, plus some additional topics. It takes a breadth-first approach, with an emphasis on the principles which form the foundation for hardware and software. No prior experience with programming should be required to use this book. This version of the book uses the C++ programming language.https://rdw.rowan.edu/oer/1025/thumbnail.jp