Defense Notices

Event Studies in finance have focused on traditional news headlines to assess the impact an event has on a traded company. The increased proliferation of news and information produced by social media content has disrupted this trend. Although researchers have begun to identify trading opportunities from social media platforms, such as Twitter, almost all techniques use a general sentiment from large collections of tweets. Though useful, general sentiment does not provide an opportunity to indicate specific events worthy of affecting stock prices.

The surface-elevation of ice sheets and sea ice is currently measured using both satellite and airborne radar altimeters. These measurements are used for generating mass balance estimates of ice sheets and thickness estimates of sea ice. However, due to the penetration of the altimeter signal into the snow there is ambiguity between the surface tracking point and the actual surface location which produces errors in the surface elevation measurement. In order to address how the penetration of the signal affects the shape of the return waveform, it is important to study the effect sub-surface scattering and seasonal variations in properties of snow have on the return waveform to correctly interpret the satellite radar altimeter data. To address this problem, an ultra-wide bandwidth Ku-band radar altimeter was developed at the Center for Remote Sensing of Ice Sheets (CReSIS). The Ku-band altimeter operates over the frequency range of 12 to 18 GHz providing very fine resolution to measure ice surface and resolve the sub-surface features of the snow. It is designed to encompass the frequency band of satellite radar altimeters. The data from Ku-band altimeter can be used to simulate satellite radar altimeter data, and these simulated waveforms can help us understand the effect of signal penetration and sub-surface scattering on low bandwidth satellite altimeter returns. The extensive dataset collected as a part of the Operation Ice Bridge (OIB) campaign can be used to interpret satellite radar altimeter data over surfaces with varying snow conditions. The goal of this research is to use waveform modeling and data inter-comparisons of full and reduced bandwidth data products from Ku-band radar altimeter to investigate the effect of signal penetration and snow conditions on surface tracking using threshold and waveform fitting retracking algorithms to improve the retrieval of surface elevation from satellite radar altimeters.

High rate data transmission is very common in cellular and wireless local area networks. It is achievable because of its wired backbone where only the first or the last hop is wireless, commonly known as wireless “last-mile” link. With this type of infrastructure network, it is not surprising to achieve the desired performance of wirelessly-transmitted video. However, the current challenge is to transmit an enunciated and a high quality real time video over multiple wireless hops in an ad hoc network. The performance of multiple wireless hops to transmit a high quality video is limited by data rate, bandwidth of wireless channel and interference from adjacent channels. These factors constrain the applications for a wireless multihop network but are fundamental to military tactical network solutions. The project addresses and studies the effect of packet sensitivity, latency, bitrate and bandwidth on the quality of video for line of sight and non-line of sight test scenarios. It aims to achieve the best visual user experience at the receiver end on transmission over multiple wireless hops. Further, the project provides an algorithm for placement of drones in sub-terrain environment to stream real time videos for border surveillance to monitor and detect unauthorized activity.

The Treatise on Invertebrate Paleontology (TIP) is a definitive work completed by more than 300 authors in the field of Paleontology, covering all categories of invertebrate animals. The digital version for TIP is consisted of multiple PDF files, however, these files are just a clone of paper version and are not well formatted, which makes it hard to extract structured data using only straightforward methods. In order to make fossil and extant records in TIP organized and searchable from a web interface, a digital library which is called Invertebrate Paleontology Knowledgebase (IPKB) was built for information sharing and querying in TIP. It is consisted of a database which stores records of all fossils and extant invertebrate animals, and a web interface which provides an online access. 
The existing IPKB system provides a general framework for TIP information showing and searching, however, it has very limited search functions, only allowing users querying by pure text. Details of structural properties in the fossil descriptions are not carefully taken into consideration. Moreover, sometimes users cannot provide correct and rich enough query terms. Although authors of TIP are all paleontologists, the expected users of IPKB may not be that professional. 
In order to overcome this limitation and bring more powerful search features into the IPKB system, in this thesis, we present a content-based search function, which allow users to search using textual ontology descriptions and images of fossils. First, this thesis describes the work done by previous research on IPKB system. Except for the original text and image processing approaches, we also present our new efforts on improving these original methods. Second, this thesis presents the algorithm and approach adopted in the construction of content-based search system for IPKB. The search functions in the old IPKB system did not consider the differences among morphological details of certain regions of fossils. Three major parts are discussed in detail: (1) Textual ontology based search. (2) Image based search. (3) Text-image based search. 

Participation in social networking sites has dramatically increased in recent years. Services such as Linkedin, Facebook, or Twitter allow millions of individuals to create online profiles and share personal information with vast networks of friends - and, often, unknown numbers of strangers. The relation between privacy and a person’s social network is multi-faced. At certain occasions we want information about ourselves to be know only to a limited set of people, and not to strangers. Privacy implications associated with online social networking depend on the level of identifiability of the information provided, its possible recipients, and its possible uses. Even social networking websites that do not openly expose their users’ identities may provide enough information to identify profile’s owner. 

With the advent of general-purpose programming tools and newer GPUs, programmers now have access to a more flexible general-purpose approach to using GPUs for something other than graphics. With single instruction stream, multiple data streams (SIMD), the same instruction is executed by multiple processors using different data streams. GPUs are SIMD computers that exploit data-level parallelism by applying the same operations to multiple items of data in parallel. There are many areas where GPUs can be used for general-purpose computing. We have chosen to focus on a project in the astrophysics area of scientific computing called N-body simulation which computes the evolution of a system of bodies that interact with each other. Each body represents an object such as a planet or a star, and each exerts a gravitational force on all the others. It is performed by using a numerical integration method to compute the interactions among the system of bodies, and begins with the initial conditions of the system which are the masses and starting position and velocity of every body. These data are repeatedly used to compute the gravitational force between all bodies of the system to show updates on screen. We investigate alternative implementation approaches to the problem in an attempt to determine the factors that maximize its performance, including speed and accuracy. Specifically, we compare an OpenCL approach to one based on using OpenGL Compute Shaders. We select these two for comparison to generate real-time interactive displays with OpenGL. Ultimately, we anticipate our results will be generalizable to other APIs (e.g., CUDA) as well as to applications other than the N-Body problem. A comparison of various numerical integration and memory optimization techniques is also included in our analysis in an attempt to understand how they work in the SIMD GPGPU environment and how they contribute to our performance metrics. We conclude that, for our particular implementation of the problem, taking advantage of efficiently using local memory considerably increases performance.

The number of vehicle manufacturers and the number of vehicles produced have been significantly increasing each year. With more vehicles on road, the number of accidents on the National Highways in the US increased notably. NHTSA (National Highway Traffic Safety Agency) is a federal agency which works towards preventing vehicle crashes and their attendant costs. They plan and execute several operations and control measures to find and solve the problems causing accidents. One such initiative is to analyze the primary causes of all the vehicle crashes and maintain a streamlined data of vehicle Identification catalog customized for DOT and NHTSA. Maintaining a data on about 250+ millions of vehicles and analyze them needs a robust database and an application for its maintenance. At StrongBridge Corporation, we developed VPICLIST, an application for NHTSA to assist their analytic projects with data entry and pattern decoding of VIN information catalog. The application employs precise pattern matching techniques to dump data into distributed databases which in turn collaborate to a central database of NHTSA. It allows decoding of VIN each at a time by the public and also decoding thousands of VINS simultaneously for internal use of NHTSA. To hold and operate upon several PBs of data, insertion and retrieval process of the application emulates a distributed architecture. The application is developed in Java and uses Oracle enterprise database for distributed small collections and NoSQL system for the central database.

The study of shear wave velocity (Vs) of near surface materials has been one of the primary areas of interest in seismic analyses. ‘Vs’ serves as the best indicator in evaluating the stiffness of a material from its shear modulus. One of the economical methods to obtain Vs profiling information is through the analysis of dispersion property of surface waves. SurfSeis4 - Software developed by the Kansas Geological Survey (KGS) utilizes Multichannel Analysis of Surface Waves (MASW) method to obtain shear wave velocity 2D (Surface location and depth) profiling. The profiling information is obtained in the form of a grid through inversion of dispersion curves. The Vs 2D map module of SurfSeis4, integrates the functionality of interpolating this grid to approximate the variation of shear wave velocity across the surface locations. The current project is an extension of the existing SurfSeis4 Vs 2D mapping module in its latest release of SurfSeis5 that incorporates topography in shear wave velocity variation and facilitates users with advanced image interpolation options.

One of the main components in switching power supply is switch. However, there are two main negative issues the switch will cause in a switching power supply. The first one is that the power dissipation of the switch will be unimaginable high, especially when the current go through the switch gets higher. Secondly, because there are so many parasitic inductances and capacitances in the circuit, transient will cause problems when the operating state of the switch changes. In this project, P-Spice is used to design a qualify swith and suppress the negative effect as much as possible. The purpose of this project is to design a switch for hardware design in switching power supplies. Therefore, all the components used in P-Spice simulation are the actual models which is able to get from electronic market, and all the situations which may be happen in hardware design will be consider in the simulation. Both Mosfet and bipolar transistor switch will be discussed in the project. The project will give solutions for reducing the power dissipation cause by the switch and transient problems.

Packet Filtering is a process of filtering the packets based on the filters rules that are being defines by the user. The focus of this project is to implement and compare the performance of two different packet filtering techniques (SFSA and PFSA), that uses FSA(finite state automaton) for the filtering process. Stateless FSA(SFSA) is a packet filtering technique where an FSA is generated based on the input packet and the filtering criteria. Then succeed early algorithm is applied to the automaton which simplifies by the automaton by shortening long trails to the the final state which reduces the packet filtering time. It also uses transition compaction algorithm which helps in avoiding certain areas in packet inspection which are not necessary for packet filtering. 
PFSA (predicates of FSA) does the filtering based on predicates generated by the predicate evaluator. In this filtering process the FSA generated as state transitions which depend on the input symbol and also the predicate value. In order to simplify the FSA algorithms like predicates Cartesian product and predicates anticipation algorithms are being used. These algorithms consider all states that are possible and merge them to make the FSA deterministic. There is also a proto FSA that is being generated for the predicates to speed up the filtering process.