Predictive Duty Cycle Adaptation for Wireless Camera Networks

Wireless sensor networks (WSN) typically employ dynamic duty cycle schemes to efficiently handle different patterns of communication traffic in the network. However, existing duty cycling approaches are not suitable for event-driven WSN, in particular, camera-based networks designed to track humans and objects. A characteristic feature of such networks is the spatially-correlated bursty traffic that occurs in the vicinity of potentially highly mobile objects. In this paper, we propose a concept of indirect sensing in the MAC layer of a wireless camera network and an active duty cycle adaptation scheme based on Kalman filter that continuously predicts and updates the location of the object that triggers bursty communication traffic in the network. This prediction allows the camera nodes to alter their communication protocol parameters prior to the actual increase in the communication traffic. Our simulations demonstrate that our active adaptation strategy outperforms TMAC not only in terms of energy efficiency and communication latency, but also in terms of TIBPEA, a QoS metric for event-driven WSN

Does Exchange Rate Variability Matter for Welfare? A Quantitative Investigation of Stabilization Policies

This paper evaluates quantitatively the potential welfare gains from monetary policy and fixed exchange rate rules in a two-country sticky-price model. The first finding is that the gains from stabilization tend to be small in the types of economic environments emphasized in recent theoretical literature. The analysis goes on to identify two types of economies in which the welfare implications of risk are larger: where agents exhibit habits, and where international asset markets exhibit asymmetry in the form of “original sin.” In the habits case, monetary policy aimed solely at inflation stabilization is optimal. But in the original sin case there are potentially large welfare gains from also eliminating exchange rate volatility.exchange rate risk, second order approximation

A Parallel Histogram-based Particle Filter for Object Tracking on SIMD-based Smart Cameras

We present a parallel implementation of a histogram-based particle filter for object tracking on smart cameras based on SIMD processors. We specifically focus on parallel computation of the particle weights and parallel construction of the feature histograms since these are the major bottlenecks in standard implementations of histogram-based particle filters. The proposed algorithm can be applied with any histogram-based feature sets—we show in detail how the parallel particle filter can employ simple color histograms as well as more complex histograms of oriented gradients (HOG). The algorithm was successfully implemented on an SIMD processor and performs robust object tracking at up to 30 frames per second—a performance difficult to achieve even on a modern desktop computer

Consumption, Housing Collateral, and the Canadian Business Cycle

Using Bayesian methods, we estimate a small open economy model in which consumers face limits to credit determined by the value of their housing stock. The purpose of this paper is to quantify the role of collateralized household debt in the Canadian business cycle. Our findings show that the presence of borrowing constraints improves the performance of the model in terms of overall goodness of fit. In particular, the presence of housing collateral generates a positive correlation between consumption and house prices. Finally we find that housing collateral induced spillovers account for a large share of consumption growth during the housing market boom-bust cycle of the late 1980s.Business fluctuations and cycles; Credit and credit aggregates; Transmission of monetary policy

Quadratic to linear magnetoresistance tuning in TmB4

The change of a material's electrical resistance (R) in response to an external magnetic field (B) provides subtle information for the characterization of its electronic properties and has found applications in sensor and storage related technologies. In good metals, Boltzmann's theory predicts a quadratic growth in magnetoresistance (MR) at low B, and saturation at high fields. On the other hand, a number of nonmagnetic materials with weak electronic correlation and low carrier concentration for metallicity, such as inhomogeneous conductors, semimetals, narrow gap semiconductors and topological insulators, two-dimensional electron gas (2DEG) show positive, non-saturating linear magnetoresistance (LMR). However, observation of LMR in single crystals of a good metal is rare. Here we present low-temperature, angle dependent magnetotransport in single crystals of the antiferromagnetic metal, TmB4. We observe large, positive and anisotropic MR(B), which can be tuned from quadratic to linear by changing the direction of the applied field. In view of the fact that isotropic, single crystalline metals with large Fermi surface (FS) are not expected to exhibit LMR, we attribute our observations to the anisotropic FS topology of TmB4. Furthermore, the linear MR is found to be temperature-independent, suggestive of quantum mechanical origin.Comment: 14 pages, 5 figures, Accepted version of PR