Cycle II.5 aircraft aero-optical turbulent boundary-layer/shear-layer measurements

The aero-optical effects associated with propagating a laser beam through aircraft turbulent boundary layers and shear layers were examined. Observed laser optical performance levels were compared with those inferred from aerodynamic measurements of unsteady densities and correlation lengths within these random flows. Optical instrumentation included a fast shearing interferometer (FSI). A 9 cm diameter collimated helium neon laser beam made a double pass through the aircraft random flow via an airfoil mirror located one meter from the fuselage. Typical aircraft turbulent boundary layer thickness measured 0.3 meters. Averaging many FSI generated modulation transfer functions (MTFs) and Fourier transforming, this average yields the expected far field intensity degradation associated with an aircraft mounted laser system. Aerodynamic instrumentation included fine wire probes to measure unsteady temperature and mass flux. A laser doppler velocimeter measured unsteady velocity within the flows. An analysis of these data yielded point measurements of unsteady density and correlation length

Induced voltage in an open wire

A puzzle arising from Faraday's law is considered and solved concerning the question which voltage is induced in an open wire with a time-varying homogeneous magnetic field. In contrast to closed wires where the voltage is determined by the time variance of magnetic field and enclosed area, in an open wire we have to integrate the electric field along the wire. It is found that the longitudinal electric field contributes with 1/3 and the transverse field with 2/3 to the induced voltage. In order to find the electric fields the sources of the magnetic fields are necessary to know. The representation of a homogeneous and time-varying magnetic field implies unavoidably a certain symmetry point or symmetry line which depend on the geometry of the source. As a consequence the induced voltage of an open wire is found to be the area covered with respect to this symmetry line or point perpendicular to the magnetic field. This in turn allows to find the symmetry points of a magnetic field source by measuring the voltage of an open wire placed with different angles in the magnetic field. We present exactly solvable models for a symmetry point and for a symmetry line, respectively. The results are applicable to open circuit problems like corrosion and for astrophysical applications

Inviscid Flow Field Effects: Experimental results

The aero-optical distortions due to invisid flow effects over airborne laser turrets is investigated. Optical path differences across laser turret apertures are estimated from two data sources. The first is a theoretical study of main flow effects for a spherical turret assembly for a Mach number (M) of 0.6. The second source is an actual wind tunnel density field measurement on a 0.3 scale laser turret/fairing assembly, with M = 0.75. A range of azimuthal angles from 0 to 90 deg was considered, while the elevation angle was always 0 deg (i.e., in the plane of the flow). The calculated optical path differences for these two markedly different geometries are of the same order. Scaling of results to sea level conditions and an aperture diameter of 50 cm indicated up to 0.0007 cm of phase variation across the aperture for certain forward look angles and a focal length of F = -11.1 km. These values are second order for a 10.6 micron system

Innovations in energy and climate policy: lessons from Vermont

We ask in this article: how can planners and policymakers replicate Vermont’s energy and climate policies? We begin by explaining the research methods utilized for this article—mainly research interviews with a pool of experts, coupled with a targeted literature review. We then analyze the success of Vermont energy policy across four areas: energy efficiency, renewable energy, the smart grid, and energy governance. The following sections first explain how Vermont accomplished these successes, next identify a number of remaining barriers and elements of Vermont’s approach that may not be replicable, and finally present the article’s conclusions

Allocating Transmission to Mitigate Market Power in Electricity Networks

We ask what conditions transmission contracts increase or mitigate market power. We show that the allocation process of transmission rights is crucial. In an efficient arbitraged uniform price auction, generators will only obtain contracts that mitigate their market power. However, if generators inherit transmission contracts or buy them in a ‘pay-as-bid’ auction, then these contracts can enhance market power. In the two-node network case, banning generators from holding transmission contracts that do not correspond to delivery of their own energy mitigates market power. Meshed networks differ in important ways as constrained links no longer isolate prices in competitive markets from market manipulation. The paper suggests ways of minimising market power considerations when designing transmission contracts.electricity, contracts, auction, network, transmission

Is Innovation King at the Antitrust Agencies? The Intellectual Property Guidelines Five Years Later

The Microsoft antitrust case focused public attention on the role of antitrust enforcement in preserving the forces of innovation in high-technology markets. Traditionally, regulators focused on whether companies artificially hiked prices or reduced output. Now, they're increasingly likely to look first at whether corporate behavior aids or impedes innovation. In this paper, we examine whether innovation has displaced short-term price effects as the focus of antitrust enforcement by the Department of Justice and the Federal Trade Commission and, to the extent that it has, whether enforcement actions are any different as a result. We also ask whether enforcement actions in the area of intellectual property and innovation have been consistent with the 1995 DOJ/FTC Antitrust Guidelines for the Licensing of Intellectual Property [IP Guidelines]. Finally, we consider whether recent enforcement actions identify key areas in which additional guidance from the Agencies would be desirable. We address these questions first in merger cases and then in non-merger cases.

Integrated structure/control law design by multilevel optimization

A new approach to integrated structure/control law design based on multilevel optimization is presented. This new approach is applicable to aircraft and spacecraft and allows for the independent design of the structure and control law. Integration of the designs is achieved through use of an upper level coordination problem formulation within the multilevel optimization framework. The method requires the use of structure and control law design sensitivity information. A general multilevel structure/control law design problem formulation is given, and the use of Linear Quadratic Gaussian (LQG) control law design and design sensitivity methods within the formulation is illustrated. Results of three simple integrated structure/control law design examples are presented. These results show the capability of structure and control law design tradeoffs to improve controlled system performance within the multilevel approach

Collective Choice and Control Rights in Firms

Recent writers have asserted that firms controlled by workers are rare because workers have diverse preferences over firm policies, and thus suffer from high transaction costs in making collective decisions. This is contrasted with firms controlled by investors, who all support the goal of wealth maximization. However, the source of the asymmetry between capital and labor has not been clearly identified. For example, firms could attract labor inputs by selling transferable shares, and well-known unanimity theorems from the finance literature carry over to models of this kind. We resolve this puzzle by arguing that because financial capital is exceptionally mobile, capital markets are sufficiently competitive to induce unanimity. The lower mobility of human capital implies that labor markets are monopolistically competitive and hence that unanimity cannot be expected in labor-managed firms. Moreover, such firms are vulnerable to takeover by investors while capital-managed firms are substantially less vulnerable to takeover by workers.capitalist firms, labor-managed firms, collective choice, preference heterogeneity, unanimity, voting, membership markets, control rights

Sparse Approximation Via Iterative Thresholding

The well-known shrinkage technique is still relevant for contemporary signal processing problems over redundant dictionaries. We present theoretical and empirical analyses for two iterative algorithms for sparse approximation that use shrinkage. The GENERAL IT algorithm amounts to a Landweber iteration with nonlinear shrinkage at each iteration step. The BLOCK IT algorithm arises in morphological components analysis. A sufficient condition for which General IT exactly recovers a sparse signal is presented, in which the cumulative coherence function naturally arises. This analysis extends previous results concerning the Orthogonal Matching Pursuit (OMP) and Basis Pursuit (BP) algorithms to IT algorithms