A nested polyhedra model of turbulence

A discretization of the wave-number space is proposed, using nested polyhedra, in the form of alternating dodecahedra and icosahedra that are self-similarly scaled. This particular choice allows the possibility of forming triangles using only discretized wave-vectors when the scaling between two consecutive dodecahedra is equal to the golden ratio, and the icosahedron between the two dodecahedra is the dual of the inner dodecahedron. Alternatively, the same discretization can be described as a logarithmically spaced (with a scaling equal to the golden ratio), nested dodecahedron-icosahedron compounds. A wave-vector which points from the origin to a vertex of such a mesh, can always find two other discretized wave-vectors that are also on the vertices of the mesh (which is not true for an arbitrary mesh). Thus, the nested polyhedra grid can be thought of as a reduction (or decimation) of the Fourier space using a particular set of self-similar triads aranged approximately in a spherical form. For each vertex (i.e. discretized wave-vector) in this space, there are either 9 or 15 pairs of vertices (i.e. wave-vectors) with which the initial vertex can interact to form a triangle. This allows the reduction of the convolution integral in the Navier-Stokes equation to a sum over 9 or 15 interaction pairs. Transforming the equation in Fourier space, to a network of interacting nodes, that can be constructed as a numerical model, which evolves each component of the velocity vector on each node of the network. Such a model gives the usual Kolmogorov spectrum. Since the scaling is logarithmic, and the number of nodes for each scale is constant, a very large inertial range can be considered with a much lower number of degrees of freedom. Incidentally, by assuming isotropy and a certain relation between the phases, the model can be used to systematically derive three dimensional shell models

Adaptive Synchronization of Robotic Sensor Networks

The main focus of recent time synchronization research is developing power-efficient synchronization methods that meet pre-defined accuracy requirements. However, an aspect that has been often overlooked is the high dynamics of the network topology due to the mobility of the nodes. Employing existing flooding-based and peer-to-peer synchronization methods, are networked robots still be able to adapt themselves and self-adjust their logical clocks under mobile network dynamics? In this paper, we present the application and the evaluation of the existing synchronization methods on robotic sensor networks. We show through simulations that Adaptive Value Tracking synchronization is robust and efficient under mobility. Hence, deducing the time synchronization problem in robotic sensor networks into a dynamic value searching problem is preferable to existing synchronization methods in the literature.Comment: First International Workshop on Robotic Sensor Networks part of Cyber-Physical Systems Week, Berlin, Germany, 14 April 201

Designing and Documenting the Behavior of Software

The development and maintenance of today's software systems is an increasingly effort-consuming and error-prone task. A major cause of this problem is the lack of formal and human-readable documentation of software design. In practice, software design is often informally documented (e.g. texts in a natural language, `boxes-and-arrows' diagrams without well-defined syntax and semantics, etc.), or not documented at all. Therefore, the design cannot be properly communicated between software engineers, it cannot be formally analyzed, and the conformance of an implementation to the design cannot be formally verified.\ud \ud In this chapter, we address this problem for the design and documentation of the behavior implemented in procedural programs. We introduce a solution that consists of three components: The first component is a graphical language called VisuaL, which enables engineers to specify constraints on the possible sequences of function calls from a given program. Since the specifications may be inconsistent with each other, the second component of our solution is a tool called CheckDesign, which automatically\ud verifies the consistency between multiple specifications written in VisuaL. The third component is a tool called CheckSource, which automatically verifies that a given implementation conforms to the corresponding specifications written in VisuaL.\ud \ud This solution has been evaluated empirically through controlled experiments with 71 participants: 23 professional developers of ASML, and 49 Computer Science M.Sc. students. These experiments showed that, with statistical significance of 0.01, the solution reduced the effort of typical maintenance tasks by 75% and\ud prevented one error per 140 lines of source code

Economic modeling of carbon dioxide integrated pipeline network for enhanced oil recovery and geologic sequestration in the Texas Gulf Coast region

Naturally occurring CO2 is transported via pipelines to oil fields in West Texas to enhance production. A similar pipeline system is proposed for the Gulf Coast region of Texas. The CO2 would come from anthropogenic sources. Using GIS data, oil fields and CO2 sources are selected and a pipeline route is designed, taking into consideration rights of way and environmental sensitivities. We modified several pipeline cost models from the literature to capture recent construction cost escalations. Our resulting cost estimates agree with mid-to-high range cost quotes for pipelines reported to the Federal Energy Regulatory Commission by the companies.Bureau of Economic Geolog