12,689 research outputs found
Time-Frequency Analysis Reveals Pairwise Interactions in Insect Swarms
The macroscopic emergent behavior of social animal groups is a classic example of dynamical self-organization, and is thought to arise from the local interactions between individuals. Determining these interactions from empirical data sets of real animal groups, however, is challenging. Using multicamera imaging and tracking, we studied the motion of individual flying midges in laboratory mating swarms. By performing a time-frequency analysis of the midge trajectories, we show that the midge behavior can be segmented into two distinct modes: one that is independent and composed of low-frequency maneuvers, and one that consists of higher-frequency nearly harmonic oscillations conducted in synchrony with another midge. We characterize these pairwise interactions, and make a hypothesis as to their biological function
Quantum Geometry and Quantum Gravity
The purpose of this contribution is to give an introduction to quantum
geometry and loop quantum gravity for a wide audience of both physicists and
mathematicians. From a physical point of view the emphasis will be on
conceptual issues concerning the relationship of the formalism with other more
traditional approaches inspired in the treatment of the fundamental
interactions in the standard model. Mathematically I will pay special attention
to functional analytic issues, the construction of the relevant Hilbert spaces
and the definition and properties of geometric operators: areas and volumes.Comment: To appear in the AIP Conference Proceedings of the XVI International
Fall Workshop on Geometry and Physics, Lisbon - Portugal, 5-8 September 200
Investment Strategies to Exploit Economic Growth in China
Since the beginning of the economic reforms two decades ago, the economy in China has enjoyed a real growth rate of 9.6 percent per year. We believe that China is only in the early stages of its rapid-growth period. China is likely to enjoy rapid growth for decades to come at rates well above those of any other large country in the world.
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RP Process Selection for Rapid Tooling in Sand Casting
The significant cycle-time improvements and geometrical capabilities of solid freeform
fabrication systems have led to applications in sand casting industry for design verification and
tooling. The time and cost effective deployment of rapid tooling processes using rapid
prototyping technology has thus becoming an emerging area to be studied. To make full use of
the advantages of rapid prototyping processes, the factors influencing the tooling approach must
be identified and understood. This understanding is then used to develop a decision-making
structure for RP process selection for rapid tooling in sand casting. In this manuscript we review
our work in evaluating and building a framework for tooling process selection for sand castingMechanical Engineerin
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