Separation of Test-Free Propositional Dynamic Logics over Context-Free Languages

For a class L of languages let PDL[L] be an extension of Propositional Dynamic Logic which allows programs to be in a language of L rather than just to be regular. If L contains a non-regular language, PDL[L] can express non-regular properties, in contrast to pure PDL. For regular, visibly pushdown and deterministic context-free languages, the separation of the respective PDLs can be proven by automata-theoretic techniques. However, these techniques introduce non-determinism on the automata side. As non-determinism is also the difference between DCFL and CFL, these techniques seem to be inappropriate to separate PDL[DCFL] from PDL[CFL]. Nevertheless, this separation is shown but for programs without test operators.Comment: In Proceedings GandALF 2011, arXiv:1106.081

Towards an Airframe Noise Prediction Methodology: Survey of Current Approaches

In this paper, we present a critical survey of the current airframe noise (AFN) prediction methodologies. Four methodologies are recognized. These are the fully analytic method, CFD combined with the acoustic analogy, the semi-empirical method and fully numerical method. It is argued that for the immediate need of the aircraft industry, the semi-empirical method based on recent high quality acoustic database is the best available method. The method based on CFD and the Ffowcs William- Hawkings (FW-H) equation with penetrable data surface (FW-Hpds ) has advanced considerably and much experience has been gained in its use. However, more research is needed in the near future particularly in the area of turbulence simulation. The fully numerical method will take longer to reach maturity. Based on the current trends, it is predicted that this method will eventually develop into the method of choice. Both the turbulence simulation and propagation methods need to develop more for this method to become useful. Nonetheless, the authors propose that the method based on a combination of numerical and analytical techniques, e.g., CFD combined with FW-H equation, should also be worked on. In this effort, the current symbolic algebra software will allow more analytical approaches to be incorporated into AFN prediction methods

American Society of Clinical Oncology Summit on Addressing Obesity Through Multidisciplinary Provider Collaboration: Key Findings and Recommendations for Action

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139117/1/oby21987.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139117/2/oby21987_am.pd

Propositional dynamic logic of looping and converse is elementarily decidable

Propositional dynamic logic is a formal system for reasoning about the before—after behavior of regular program schemes. An extension of propositional dynamic logic which includes both an infinite looping construct and a converse or backtracking construct is considered and it is proved that the satisfiability problem for this logic is elementarily decidable. In order to establish this result, deterministic two-way automata on infinite trees are defined, and it is shown how they can be simulated by nondeterministic one-way automata. The satisfiability problem for propositional dynamic logic of looping and converse is then reduced to the emptiness problem for these two-way automata

Aeroacoustic Experiments in the Langley

A phased microphone array was used in the Langley Low-Turbulence Pressure Tunnel to obtain the radiated acoustic field from high-lift wing configurations that included a slat and a part-span flap. The data included noise localization maps and acoustic spectra