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Liang J.-C.,National Tsing Hua University | Chen J.-C.,National Chiao Tung University | Zhang T.,Applied Research
Wireless Networks | Year: 2011

In this paper we propose a Distributed Hash Table (DHT)-based peer-to-peer resource discovery protocol designed for large-scale Mobile Ad-hoc NETwork (MANET). The proposed Mobile Resource Discovery Protocol (MRDP) uses a distributed dynamic clustering algorithm to adaptively and rapidly group nodes in a MANET for resource discovery purpose, and utilizes DHTs to efficiently cache resource information in a peer-to-peer manner. We provide a probabilistic lower bound on the performance of the MRDP. We also present simulation results under different scenarios to show that MRDP has low message overheads and its performance is highly insensitive to the size of the MANET. These characteristics make MRDP suitable for large-scale MANETs. © 2010 Springer Science+Business Media, LLC.


Ferrebee E.C.,University of Illinois at Urbana - Champaign | Brand A.S.,University of Illinois at Urbana - Champaign | Kachwalla A.S.,University of Illinois at Urbana - Champaign | Roesler J.R.,University of Illinois at Urbana - Champaign | And 2 more authors.
Transportation Research Record | Year: 2014

Roller-compacted concrete (RCC) pavement has renewed interest among designers as a sustainable pavement option with the potential to lower total cement content, incorporate recycled aggregates, reduce road closure time, and decrease total project costs. One main design challenge is whether RCC can achieve the same performance life as conventional Portland cement concrete (PCC) pavement with similar slab thickness. This research investigated the strength and fracture properties of RCC containing virgin aggregates and fractionated reclaimed asphalt pave-ment (FRAP) relative to conventional PCC to address this design challenge. The compressive and split tensile strengths of the RCC mixes showed similar strengths to the same constituents in PCC. RCC containing FRAP had lower strengths than did RCC with virgin aggregates. The critical stress intensity factor and the initial and total fracture energies were not statistically different between the RCC mixes containing virgin and F RAP aggregates. Overall, the RCC fracture properties were found to lie significantly higher than those of conventional PCC. At lower stress ratios RCC fatigue data from laboratory beam tests predict lower fatigue life relative to PCC; this result translates to a thicker RCC pavement, large-scale testing has shown that the flexural capacity of PCC slabs is strongly related to the concrete fracture properties despite differences in beam flexural strength. Because these RCC fracture properties were shown to be higher than similar constituents used in conventional paving concrete, RCC designs could employ similar PCC fatigue curves for certain conditions, such as when (lie RCC fracture properties are equivalent to or greater than those of conventional PCC.


Younis O.M.,Applied Research | Krunz M.M.,University of Arizona | Ramasubramanian S.,University of Arizona
IEEE/ACM Transactions on Networking | Year: 2011

We consider surveillance applications in which sensors are deployed in large numbers to improve coverage fidelity. Previous research has studied how to select active sensor covers (subsets of nodes that cover the field) to efficiently exploit redundant node deployment and tolerate unexpected node failures. Little attention was given to studying the tradeoff between fault tolerance and energy efficiency in sensor coverage. In this work, our objectives are twofold. First, we aim at rapidly restoring field coverage under unexpected sensor failures in an energy-efficient manner. Second, we want to flexibly support different degrees of redundancy in the field without needing centralized control. To meet these objectives, we propose design guidelines for applications that employ distributed cover-selection algorithms to control the degree of redundancy at local regions in the field. In addition, we develop a new distributed technique to facilitate switching between active covers without the need for node synchronization. Distributed cover selection protocols can be integrated into our referred to as resilient online coverage (ROC) framework. A key novelty in ROC is that it allows every sensor to control the degree of redundancy and surveillance in its region according to current network conditions. We analyze the benefits of ROC in terms of energy efficiency and fault tolerance. Through extensive simulations, we demonstrate the effectiveness of ROC in operational scenarios and compare its performance with previous surveillance techniques. © 2010 IEEE.


Heiselberg H.,Applied Research
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

Itinerant ferromagnetism in cold Fermi gases with repulsive interactions is studied applying the Jastrow-Slater approximation generalized to finite polarization and temperature. For two components at zero temperature, a second-order transition is found at akF0.90 compatible with results of quantum-Monte-Carlo (QMC) calculations. Thermodynamic functions and observables, such as the compressibility and spin susceptibility and the resulting fluctuations in number and spin, are calculated. For trapped gases, the resulting cloud radii and kinetic energies are calculated and compared to recent experiments. Spin-polarized systems are recommended for effective separation of large ferromagnetic domains. Collective modes are predicted and tricritical points are calculated for multicomponent systems. © 2011 American Physical Society.


Jia Z.,Applied Research
2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010 | Year: 2010

Convergence of optical and wireless systems with higher bandwidth is one of the most promising solutions for increasing the existing capacity and mobility in next-generation access networks. Some specific topics that will be highlighted include photonic generation and processing technologies toward high flexibility, integration, and spectrum efficiency. ©2010 IEEE.

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