Optimal Hankel Norm Model Reduction by Truncation of Trajectories

We show how optimal Hankel-norm approximations of dynamical systems allow for a straightforward interpretation in terms of system trajectories. It is shown that for discrete time single-input systems optimal reductions are obtained by cutting 'balanced trajectories', i.e., by disconnecting the past and future in the input-output pairs relating to left- and right singular vectors of the system. A self-contained proof of optimality is given, and formulas are derived in terms of Faddeev sequences. Some parallels with the literature are briefly indicated.Optimal Hankel norm approximation;Balancing;Linear systems;l2-systems;Faddeev sequences

A multi-sensor system for robotics proximity operations

Robots without sensors can perform only simple repetitive tasks and cannot cope with unplanned events. A multi-sensor system is needed for a robot to locate a target, move into its neighborhood and perform operations in contact with the object. Systems that can be used for such tasks are described

A direct comparison of metonymic and metaphoric relations in adjective–noun pairs

Theories on metaphor and metonymy make different claims about the nature of the underlying processes in the computation of these two types of language use, i.e., whether they differ or not. Experimental investigations of metonymy and metaphor have generally not compared these two phenomena in a straightforward manner among others due to structural variability. To overcome this shortcoming, we conducted a study in German that used adjective–noun combinations to contrast metaphor and metonymy directly in an ERP-study during reading for comprehension. By combining three different nouns with one adjective in predicative position we construed adjective–noun pairs with literal (the baby was lively), metonymic (the eyes were lively) or metaphoric (the speed was lively) relations. The data revealed a more pronounced N400 for the metaphoric relations in comparison to the literal controls. We argue that the enhanced cost for metaphors reflects the activation process of two unrelated domains via mapping or extended predication. The metonymic adjective–noun pairs only showed a small trend to differ from the other two conditions. This might indicate that metonymies require mapping processes or shifts only within a single domain or domain matrix. Moreover, in contrast to previous studies, we did not find a Late Positivity. We explain this result with regard to different discourse representational consequences arising during combinatorial processing

Affine Parameter-Dependent Lyapunov Functions for LPV Systems with Affine Dependence

This paper deals with the certification problem for robust quadratic stability, robust state convergence, and robust quadratic performance of linear systems that exhibit bounded rates of variation in their parameters. We consider both continuous-time (CT) and discrete-time (DT) parameter-varying systems. In this paper, we provide a uniform method for this certification problem in both cases and we show that, contrary to what was claimed previously, the DT case requires a significantly different treatment compared to the existing CT results. In the established uniform approach, quadratic Lyapunov functions, that are affine in the parameter, are used to certify robust stability, robust convergence rates, and robust performance in terms of linear matrix inequality feasibility tests. To exemplify the procedure, we solve the certification problem for $\mathscr{L}_2$-gain performance both in the CT and the DT cases. A numerical example is given to show that the proposed approach is less conservative than a method with slack variables.Comment: 8 pages, 3 figure

Aircraft Cyber Security and Information Exchange Safety Analysis for Department of Commerce

The Federal Aviation Administration’s (FAA) Next Generation Air Transportation (NextGen) program is a long-term modernization and transformation of the current National Airspace System (NAS) into a more effective and coordinated decision-making system. NextGen provides a more reliable, secure, and dependable aviation capability for both users and operators ensuring more capacity, throughput, and safety. This research delineates a high-level Safety Risk Assessment (SRA) related to NextGen technologies, specifically Aircraft Communications Addressing and Reporting System (ACARS) as well as Aircraft Access to System Wide Information Management (SWIM) network (AAtS). Other communication mediums such as Mode-S or ADS-B transponder are also data exchange and broadcast capabilities in the aircraft can also be prone to lower level safety risks primarily because of an inability to ensure information security

Photon-graviton pair conversion

We consider the conversion of gravitons and photons as a four-wave mixing process. A nonlinear coupled systems of equations involving two gravitons and two photons is obtained, and the energy exchange between the different degrees of freedom is found. The scattering amplitudes are obtained, from which a crossection for incoherent processes can be found. An analytical example is given, and applications to the early Universe are discussed.Comment: 5 pages, slightly modified as compared to v1, to appear in Class. Quantum Grav. as a Letter to the Edito

Nanoscale broadband transmission lines for spin qubit control

The intense interest in spin-based quantum information processing has caused an increasing overlap between two traditionally distinct disciplines, such as magnetic resonance and nanotechnology. In this work we discuss rigourous design guidelines to integrate microwave circuits with charge-sensitive nanostructures, and describe how to simulate such structures accurately and efficiently. We present a new design for an on-chip, broadband, nanoscale microwave line that optimizes the magnetic field driving a spin qubit, while minimizing the disturbance on a nearby charge sensor. This new structure was successfully employed in a single-spin qubit experiment, and shows that the simulations accurately predict the magnetic field values even at frequencies as high as 30 GHz.Comment: 18 pages, 8 figures, 1 table, pdflate