1,371 research outputs found

    Executive computer program for linking independent computer programs: ODINEX

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    Program controls sequence of execution of network of program elements and maintains data base of common information which forms communication link among them. Approach is applicable to any multiple-program task

    High performance dash on warning air mobile, missile system

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    An aircraft-missile system which performs a high acceleration takeoff followed by a supersonic dash to a 'safe' distance from the launch site is presented. Topics considered are: (1) technological feasibility to the dash on warning concept; (2) aircraft and boost trajectory requirements; and (3) partial cost estimates for a fleet of aircraft which provide 200 missiles on airborne alert. Various aircraft boost propulsion systems were studied such as an unstaged cryogenic rocket, an unstaged storable liquid, and a solid rocket staged system. Various wing planforms were also studied. Vehicle gross weights are given. The results indicate that the dash on warning concept will meet expected performance criteria, and can be implemented using existing technology, such as all-aluminum aircraft and existing high-bypass-ratio turbofan engines

    Gap modification of atomically thin boron nitride by phonon mediated interactions

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    A theory is presented for the modification of bandgaps in atomically thin boron nitride (BN) by attractive interactions mediated through phonons in a polarizable substrate, or in the BN plane. Gap equations are solved, and gap enhancements are found to range up to 70% for dimensionless electron-phonon coupling \lambda=1, indicating that a proportion of the measured BN bandgap may have a phonon origin

    A holistic multi-scale approach to using 3D scanning technology in accident reconstruction

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    Three-dimensional scanning and documentation methods are becoming increasingly employed by law enforcement personnel for crime scene and accident scene recording. Three-dimensional documentation of the victim’s body in such cases is also increasingly used as the field of forensic radiology and imaging is expanding rapidly. These scanning technologies enable a more complete and detailed documentation than standard autopsy. This was used to examine a fatal pedestrian-vehicle collision where the pedestrian was killed by a van whilst crossing the road. Two competing scenarios were considered for the vehicle speed calculation: the pedestrian being projected forward by the impact or the pedestrian being carried on the vehicle’s bonnet. In order to assist with this, the impact area of the accident vehicle was scanned using laser surface scanning, the victim was scanned using postmortem CT and micro-CT and the data sets were combined to virtually match features of the vehicle to injuries on the victim. Micro-CT revealed additional injuries not previously detected, lending support to the pedestrian-carry theory

    Unboundedness and downward closures of higher-order pushdown automata

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    We show the diagonal problem for higher-order pushdown automata (HOPDA), and hence the simultaneous unboundedness problem, is decidable. From recent work by Zetzsche this means that we can construct the downward closure of the set of words accepted by a given HOPDA. This also means we can construct the downward closure of the Parikh image of a HOPDA. Both of these consequences play an important role in verifying concurrent higher-order programs expressed as HOPDA or safe higher-order recursion schemes

    Rise of the centrist: from binary to continuous opinion dynamics

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    We propose a model that extends the binary ``united we stand, divided we fall'' opinion dynamics of Sznajd-Weron to handle continuous and multi-state discrete opinions. Disagreement dynamics are often ignored in continuous extensions of the binary rules, so we make the most symmetric continuum extension of the binary model that can treat the consequences of agreement (debate) and disagreement (confrontation) within a population of agents. We use the continuum extension as an opportunity to develop rules for persistence of opinion (memory). Rules governing the propagation of centrist views are also examined. Monte Carlo simulations are carried out. We find that both memory effects and the type of centrist significantly modify the variance of average opinions in the large timescale limits of the models. Finally, we describe the limit of applicability for Sznajd-Weron's model of binary opinions as the continuum limit is approached. By comparing Monte Carlo results and long time-step limits, we find that the opinion dynamics of binary models are significantly different to those where agents are permitted more than 3 opinions
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