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Phase transitions and critical phenomena: Universality and global multicritical phase diagrams from position-space renormalization-group studies

REA Auditado

The position-space renormalization-group (PSRG) approach has given impressive results in studies of phase transitions and critical phenomena. Most work has focussed on the local critical properties of rather simple models.

Tema: general: 

• Ciencias›Física

Power grid simulation, evaluation, and test framework

REA Auditado

The Virtual Power System Testbed (VPST) at the University of Illinois at Urbana-Champaign is part of the Trustworthy Cyber Infrastructure for the Power Grid (TCIP) and is maintained by members of the Information Trust
Institute (ITI). VPST is designed to be integrated with other testbeds across the country to explore performance and security of Supervisory Control and
Data Acquisition (SCADA) protocols and equipment.

Tema: general: 

• Ingeniería y Ciencias Aplicadas

The Structure of Secure Multi-Party Computation

REA Auditado

Secure multi-party computation is a conceptual framework in which distrusting parties engage in a protocol to securely perform a computational task. Depending on the precise model of security, different sets of tasks admit secure protocols. We take a complexity-theoretic approach to studying the inherent difficulty of securely realizing tasks in various standard security models. * We give the first alternate characterization of secure realizability in the framework of universally composable (UC) security.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ciencias Computacionales

Group formation and communication in mobile wi-fi networks

REA Auditado

Use of Wi-Fi-capable mobile handheld devices is gaining momentum in university campuses. In addition, students often work as a group to perform collaborative tasks on campus. Consequently, there is a demand for group communication applications in mobile devices and a need to provide middleware support for such group communication over mobile wireless networks. This paper presents three common grouping scenarios as observed in university campuses. We then present data dissemination strategies for these grouping scenarios.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ciencias Computacionales

Photoproduction of neutral pions in helium by 335 MEV Bremsstrahlung

REA Auditado

The differential cross section was measured for the, coherent production of neutral pions from He4 by photons to
an energy of 335 MeV. Bremsstrahlung from the University of
Illinois 340 MeV betatron impinged upon a gaseous He4 target
cooled to 20.4oK. The recoil nucleus was detected with a semiconductor
telescope in coincidence with at least one gamma
resulting from the decay of the neutral pion. The particle
events were recorded on photographic film in both analogue
and digital form.

Tema: general: 

• Ciencias›Física

Scalable collective message-passing algorithms

REA Auditado

Governments, universities, and companies expend vast resources
building the top supercomputers. The processors and interconnect
networks become faster, while the number of nodes grows exponentially. Problems of scale emerge, not least of which is
collective performance. This thesis identifies and proposes solutions for two major scalability problems. Our first contribution is a novel algorithm for process-partitioning
and remapping for exascale systems that has far better time and space
scaling than known algorithms.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ciencias Computacionales

Photoproduction of positive pions near threshold in hydrogen

REA Auditado

An experiment has been done to improve available
measurements of pi+ photoproduction cross sections very near
threshold 0 To do this, a 1410 hydrogen bubble chamber was
used in an X-ray beam with Emax = 230 MeV. Meson tracks could
be observed from their origins in the photon beam. Only
those events were used in which the '1T+ stopped and decayed
in the visible region of the chamber.
To suppress electron background, the X-ray beam from
the University of Illinois petatron was hardened before it
passed through the bubble chamber. Each X-ray pulse
contained a total energy of about 106 MeV.

Tema: general: 

• Ciencias›Física

Characterizing and leveraging people movement for content distribution in mobile Peer-to-Peer networks

REA Auditado

In this thesis, we present a framework to characterize and leverage people movement for improvements of content distribution in mobile Peer-to-Peer (P2P) networks.
Particularly, we study two
typical classes of people movement including the Schelling behavior and repetitive behavior. The Schelling behavior exists in real-world scenarios where co-located people collaboratively share mutual content interest when they are moving towards the same Point of Interest such as shopping mall, football stadium, and outdoor concert.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ciencias Computacionales

Photoproduction of charged pions from deuterium near threshold

REA Auditado

An experiment has been performed in order to improve existing
information on the behavior of the pi-photoproduction cross section near
threshold. To do this an X=ray beam from the University of Illinois
betatron was passed through a 14 inch liquid deuterium bubble chamber.
Each X ·-ray pulse (E max :: 230 MeV) contained a total energy of about
106 MeV. l'ne X."ray beam wa.s hardened by means of a. standard beam
. hardening technique to reduce the electron background. The X-ray beam
monitor was calibrated with an uncertainty of ± 2.4%.
A total of 140,000 usable photographs were taken.

Tema: general: 

• Ciencias›Física

Tools for acquired scene analysis and transmission

REA Auditado

Recent advancement in research and technology on virtual environments has significantly escalated users' expectations on this matter. This trend is easily witnessed, for example, by websites like twitter or facebook. Moreover, searching for 3D navigation in any search engine can provide an increasing number of instances where the full 3D models of cities are available to users for a virtual walk through. From research viewpoint, design of such virtual environments needs to address two key concepts of “user interface” and “data manipulation”.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ciencias Computacionales