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This paper describes the use of a pressure-actuated liquid metal switching mechanism to alter the polarization characteristics of printed circuit antennas. The mechanism is applied to a truncated corner patch antenna and an annular slot antenna to provide switching between linear and circular polarization.

Metamaterials have been shown to exhibit frequency and spatial dispersion. (A. Alu, arxiv.org/ftp/arxiv/papers/1012/1012.1351.pdf) In a frequency and spatially dependent medium the permittivity (e(ω, k)) and permeability (μ(ω, k)) are dependent on ω the frequency dependence and k a potential with the periodicity of the lattice in a crystal or unit cell in a metamaterial. Spatial dispersion is also dependent on the ratio period (a) of the lattice or unit cell and the free space wavelength (λ 0 ) of the incident wave where a/λ 0 < 1(V. Ginzburg, Physics Reports (Review Section of Physics Letters, 194, 12 (1990)). In this work we demonstrate the behavior of the longitudinal and transverse spatial modes in a metamaterial and show the affect of the spatial modes on the loss and negative refraction in the medium. To demonstrate the longitudinal and transverse behavior in the metamaterial we ran parametric simulations changing the geometric dimension of SRRs and wire post keeping the period of the unit cells constant. The Figure below shows a unit cell used in the simulation and the results from the simulations of e (ω, k) and μ (ω, k) for 3 unit cells. The Figure (a), (b), and (c) below also shows how the spatial dispersion varied in the unit cell as the geometrical dimensions of the SRRs and wire post were changed. The unit cells for Figure (a) and (b) were to used fabricate into slab and wedge prism structures to demonstrate the interaction of the longitudinal and transverse spatial waves with the incident wave in the medium. The frequency response and polarization behavior of the slabs and refractive behavior of the wedges were measured. Using the simulated and measured results, we are able to show the interaction between the longitudinal and transverse spatial wave and the incident wave propagating in the metamaterial and how the spatial waves affect the losses and negative refraction in the metamaterial.

An approach is suggested for arguing that a system is dependable. The key idea is to structure the system so that critical requirements are localized in small, reliable subsets of the system's components called trusted bases. This paper describes an idiom for modeling systems with trusted bases, and a technique for analyzing a dependability argument---the argument that a trusted base is sufficient to establish a requirement.

Force feedback interfaces for virtual reality are required to be “transparent”, which means that the interfaces must be light in weight but strong in stiffness. We introduced a new 6-dof parallel manipulator with such a feature. As compared to all existing 6-dof 3-legged parallel manipulators, this new system has all actuators located on the ground for a very light structure. The system has a considerably simple kinematics relationship. Another feature is that the system's interior singularity is independent on the position of the end-effector. The complete direct and inverse kinematics analysis, and workspace analysis are given in this work.

A technique is presented for obtaining a specification from a requirement through a series of incremental steps. The starting point is a Problem Frame description involving a requirement on the phenomena of the problem domain, and a decomposition of the environment into domains, connected to one another and to the machine being implemented by shared phenomena. In each step, the requirement is moved towards the machine, leaving behind a trail of 'breadcrumbs' in the form of domain assumptions. Eventually, the transformed requirement references only phenomena at the interface of the machine and can therefore serve as a specification. Each step is justified by an implication that can be mechanically checked, ensuring that, if the machine obeys the derived specification and the domain assumptions are valid, the requirement will hold. The technique is applied to the logging subproblem of a radiotherapy system.

Summary form only given. Can software really be made dependable? And if it was, would we be able to recognize it? For the last two years, the author had been chairing a study of the National Academy of Sciences on dependable software, and have had the opportunity to hear - in a workshop held last year, and in open sessions of the committee - anecdotes and viewpoints that have often surprised him. The conclusions of the committee are not made public until the final report is out. In this talk, therefore, some of the things heard are shared, and draw some connections to requirements engineering.

Lightweight formal modeling and automatic analysis were used to explore the design of the intentional naming system (INS), a new scheme for resource discovery in a dynamic networked environment. We constructed a model of INS in Alloy a lightweight relational notation, and analyzed it with the Alloy Constraint Analyzer, a fully automatic simulation and checking tool. In doing so, we exposed several serious flaws in both the algorithm of INS and the underlying naming semantics. We were able to characterize the conditions under which the existing INS scheme works correctly, and evaluate proposed fixes.