University of Winnipeg

About: University of Winnipeg is a education organization based out in Winnipeg, Manitoba, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 3235 authors who have published 6413 publications receiving 150564 citations. The organization is also known as: U of W.

Sleep and Wakeup Strategies in Solar-Powered Wireless Sensor/Mesh Networks: Performance Analysis and Optimization

Abstract: A queuing analytical model is presented to investigate the performances of different sleep and wakeup strategies in a solar-powered wireless sensor/mesh network where a solar cell is used to charge the battery in a sensor/mesh node. While the solar radiation process (and, hence, the energy generation process in a solar cell) is modeled by a stochastic process (i.e., a Markov chain), a linear battery model with relaxation effect is used to model the battery capacity recovery process. Developed based on a multidimensional discrete-time Markov chain, the presented model is used to analyze the performances of different sleep and wakeup strategies in a sensor/mesh node. The packet dropping and packet blocking probabilities at a node are the major performance metrics. The numerical results obtained from the analytical model are validated by extensive simulations. In addition, using the queuing model, based on a game-theoretic formulation, we demonstrate how to obtain the optimal parameters for a particular sleep and wakeup strategy. In this case, we formulate a bargaining game by exploiting the trade-off between packet blocking and packet dropping probabilities due to the sleep and wakeup dynamics in a sensor/mesh node. The Nash solution is obtained for the equilibrium point of sleep and wakeup probabilities. The presented queuing model, along with the game-theoretic formulation, would be useful for the design and optimization of energy-efficient protocols for solar-powered wireless sensor/mesh networks under quality-of-service (QoS) constraints

Accurate Determination of the Neutron Skin Thickness of ^{208}Pb through Parity-Violation in Electron Scattering.

Abstract: We report a precision measurement of the parity-violating asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{208}Pb. We measure A_{PV}=550±16(stat)±8(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(Q^{2}=0.00616 GeV^{2})=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is R_{n}-R_{p}=0.283±0.071 fm. The result also yields the first significant direct measurement of the interior weak density of ^{208}Pb: ρ_{W}^{0}=-0.0796±0.0036(exp)±0.0013(theo) fm^{-3} leading to the interior baryon density ρ_{b}^{0}=0.1480±0.0036(exp)±0.0013(theo) fm^{-3}. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.

The impact of IFRS on accounting quality in a regulated market : an empirical study of China

Abstract: As more countries consider the adoption of International Financial Reporting Standards (IFRS) that are based on practices prevalent in the English-speaking countries with free markets, it’s increasingly important to understand the impact of IFRS on countries of different institutional, economic, and political environments. This article reports a study that examines the impact of IFRS on accounting quality in a regulated market, China, where new substantially IFRS-convergent accounting standards became mandatory for listed firms in 2007. Accounting quality is examined for the period 2005 to 2008 with only firms mandated to follow the new standards. The empirical results generally indicate that accounting quality improved with decreased earnings management and increased value relevance of accounting measures in China since 2007. Firms audited by the Big Four are expected to have higher quality before the standard change evidenced quality improvement to a smaller extent. Further analysis shows that such chan...

Parallel random number generation for VLSI systems using cellular automata

Abstract: A novel random number generation (RNG) architecture of particular importance in VLSI for fine-grained parallel processing is proposed. It is demonstrated that efficient parallel pseudorandom sequence generation can be accomplished using certain elementary one-dimensional cellular automata (two binary states per site and only nearest-neighbor connections). The pseudorandom numbers appear in parallel from various cells in the cellular automaton on each clock cycle and pass standard empirical random number tests. Applications have been demonstrated in the design and analysis of special-purpose accelerators for Monte Carlo simulation of large intractable systems. In addition, significant advantages in pseudorandom built-in self-test of VLSI circuits using cellular automata based RNGs have been demonstrated. >

Forest biomass of china: an estimate based on the biomass–volume relationship

Abstract: In this study, a method was developed to estimate the forest biomass of China based on the relationship between stand biomass and volume. Biomass-volume relationships were quantified for all the main forest types in China using 758 sets of data obtained from direct field measurements. These relationships were used to convert volume measurements into total biomass values (above- and belowground dry masses) based on 1984-1988 forest inventory data for China. The latter had been compiled from more than 250000 permanent and temporary field plots across the country. This data contained information on forest area and timber volume for each ape class and site class for all forest types at the provincial level. As a result, the total forest biomass of China was estimated as 9103 Tg (1 Tg 10(12) g), with 8592, 326, and 185 Tg from forests, special product plantations, and bamboo Forests, respectively. The area-weighted mean biomass density was 84 Mg/ha (1 Mg = 10(6) g). For comparison, two additional estimates, one based on the mean biomass density method and another based on the mean ratio of biomass to stem volume, were also derived. Compared to the biomass-volume relationship method, the mean biomass density method considerably overestimated the forest biomass of China (by 59.6%), while the mean ratio of biomass to stem volume method slightly underestimated it (by 12.1%). Despite the small forest biomass value due to a low forest cover, the area-weighted mean biomass density was comparable to those of other regions in the middle and high latitudes except in the United States. We believe that our study provided not only an appropriate estimate of forest biomass for China, but also an improved methodology for estimating forest biomass at the regional, national, and global level.