University of Virginia

About: University of Virginia is a education organization based out in Charlottesville, Virginia, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 52543 authors who have published 113268 publications receiving 5220506 citations. The organization is also known as: U of V & UVa.

Energy-efficient surveillance system using wireless sensor networks

Abstract: The focus of surveillance missions is to acquire and verify information about enemy capabilities and positions of hostile targets. Such missions often involve a high element of risk for human personnel and require a high degree of stealthiness. Hence, the ability to deploy unmanned surveillance missions, by using wireless sensor networks, is of great practical importance for the military. Because of the energy constraints of sensor devices, such systems necessitate an energy-aware design to ensure the longevity of surveillance missions. Solutions proposed recently for this type of system show promising results through simulations. However, the simplified assumptions they make about the system in the simulator often do not hold well in practice and energy consumption is narrowly accounted for within a single protocol. In this paper, we describe the design and implementation of a running system for energy-efficient surveillance. The system allows a group of cooperating sensor devices to detect and track the positions of moving vehicles in an energy-efficient and stealthy manner. We can trade off energy-awareness and surveillance performance by adaptively adjusting the sensitivity of the system. We evaluate the performance on a network of 70 MICA2 motes equipped with dual-axis magnetometers. Our results show that our surveillance strategy is adaptable and achieves a significant extension of network lifetime. Finally, we share lessons learned in building such a complete running system.

Ideology: Its Resurgence in Social, Personality, and Political Psychology:

Abstract: We trace the rise, fall, and resurgence of political ideology as a topic of research in social, personality, and political psychology. For over 200 years, political belief systems have been classified usefully according to a single left-right (or liberal-conservative) dimension that, we believe, possesses two core aspects: (a) advocating versus resisting social change and (b) rejecting versus accepting inequality. There have been many skeptics of the notion that most people are ideologically inclined, but recent psychological evidence suggests that left-right differences are pronounced in many life domains. Implicit as well as explicit preferences for tradition, conformity, order, stability, traditional values, and hierarchy-versus those for progress, rebelliousness, chaos, flexibility, feminism, and equality-are associated with conservatism and liberalism, respectively. Conservatives score consistently higher than liberals on measures of system justification. Furthermore, there are personality and lifestyle differences between liberals and conservatives as well as situational variables that induce either liberal or conservative shifts in political opinions. Our thesis is that ideological belief systems may be structured according to a left-right dimension for largely psychological reasons linked to variability in the needs to reduce uncertainty and threat.

Theory of plastic deformation: - properties of low energy dislocation structures

Abstract: Work-hardening phenomena are based on the very fundamental principles (i) that at the position of every dislocation axis the respective resolved shear stress cannot exceed the friction stress, including the self-stress of bowing dislocations, and (ii) that always that structure forms which among those accessible by the dislocations minimizes stored energy per unit length of dislocation line. Such dislocation structures have been named LEDSs. The corresponding work-hardening theory, the mesh length theory, is applicable to all materials deforming via gliding dislocations and to all types of deformation. Results previously achieved with the mesh length theory are summarized, and a number of new developments are discussed. Depending on the dislocation structures formed, the work-hardening behavior differs. Easily intersecting glide causes dislocation cell structures with almost dislocation-free cell interiors delineated by dislocation rotation boundaries. Pronounced planar glide causes Taylor lattices characterized by local planar order parallel to the one or perhaps two most highly stressed glide plane(s), no systematic lattice rotations, and overall uniform dislocation density. The most widely observed basic features of work hardening are explained in general terms. Specific applications are indicated for layer-type crystals, h.c.p. single crystals, single-crystal and polycrystalline pure f.c.c. metals and α-brass-type alloys, precipitation-hardened materials and steels. Included are the different stages of work hardening, dynamical effects in low temperature plasticity, the general characteristics of grain boundary strengthening and the Hall-Petch relationship. In addition, proposed explanations for (i) glide system interactions in polyslip resulting in microbands and affecting texture formation, and (ii) creep without stress dependence of dislocation density, are discussed.