30,205 research outputs found
Digital computer processing of X-ray photos
Digital computers correct various distortions in medical and biological photographs. One of the principal methods of computer enhancement involves the use of a two-dimensional digital filter to modify the frequency spectrum of the picture. Another computer processing method is image subtraction
Man-machine interactive imaging and data processing using high-speed digital mass storage
The role of vision in teleoperation has been recognized as an important element in the man-machine control loop. In most applications of remote manipulation, direct vision cannot be used. To overcome this handicap, the human operator's control capabilities are augmented by a television system. This medium provides a practical and useful link between workspace and the control station from which the operator perform his tasks. Human performance deteriorates when the images are degraded as a result of instrumental and transmission limitations. Image enhancement is used to bring out selected qualities in a picture to increase the perception of the observer. A general purpose digital computer, an extensive special purpose software system is used to perform an almost unlimited repertoire of processing operations
Augmented information in a theory of ambiguity, credibility and inflation
Monetary policy - United States ; Money supply
Automobile Prices, Gasoline Prices, and Consumer Demand for Fuel Economy
The relationship between gasoline prices and the demand for vehicle fuel efficiency is important for environmental policy but poorly understood in the academic literature. We provide empirical evidence that automobile manufacturers price as if consumers respond to gasoline prices. We derive a reduced-form regression equation from theoretical micro-foundations and estimate the equation with nearly 300,000 vehicle-week-region observations over the period 2003-2006. We find that vehicle prices generally decline in the gasoline price. The decline is larger for inefficient vehicles, and the prices of particularly efficient vehicles actually rise. Structural estimation that ignores these effects underestimates consumer preferences for fuel efficiency.Automobiles, Gasoline, Consumer Preference, Demand, Fuel Efficiency
Coherent Perfect Rotation
Two classes of conservative, linear, optical rotary effects (optical activity
and Faraday rotation) are distinguished by their behavior under time reversal.
In analogy with coherent perfect absorption, where counterpropagating light
fields are controllably converted into other degrees of freedom, we show that
only time-odd (Faraday) rotation is capable of coherent perfect rotation in a
linear and conservative medium, by which we mean the complete transfer of
counterpropagating coherent light fields into their orthogonal polarization.
This highlights the necessity of time reversal odd processes (not just
absorption) and coherence in perfect mode conversion and may inform device
design.Comment: 4 pages, 2 figure
Music enrichment for gifted children in the first grade
Thesis (Ed.M.)--Boston Universit
Macroscale and Nanoscale Photoelectrochemical Behavior of p-Type Si(111) Covered by a Single Layer of Graphene or Hexagonal Boron Nitride
Two-dimensional (2D) materials may enable a general approach to the introduction of a dipole at a semiconductor surface as well as control over other properties of the double layer at a semiconductor/liquid interface. Vastly different properties can be found in the 2D materials currently studied due in part to the range of the distribution of density-of-states. In this work, the open-circuit voltage (V_(oc)) of p-Si–H, p-Si/Gr (graphene), and p-Si/h-BN (hexagonal boron nitride) in contact with a series of one-electron outer-sphere redox couples was investigated by macroscale measurements as well as by scanning electrochemical cell microscopy (SECCM). The band gaps of Gr and h-BN (0–5.97 eV) encompass the wide range of band gaps for 2D materials, so these interfaces (p-Si/Gr and p-Si/h-BN) serve as useful references to understand the behavior of 2D materials more generally. The value of V_(oc) shifted with respect to the effective potential of the contacting solution, with slopes (ΔV_(oc)/ΔE_(Eff)) of −0.27 and −0.38 for p-Si/Gr and p-Si/h-BN, respectively, indicating that band bending at the p-Si/h-BN and p-Si/Gr interfaces responds at least partially to changes in the electrochemical potential of the contacting liquid electrolyte. Additionally, SECCM is shown to be an effective method to interrogate the nanoscale photoelectrochemical behavior of an interface, showing little spatial variance over scales exceeding the grain size of the CVD-grown 2D materials in this work. The measurements demonstrated that the polycrystalline nature of the 2D materials had little effect on the results and confirmed that the macroscale measurements reflected the junction behavior at the nanoscale
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