Comparison of the predicted performance of typical HF and VHF Yagi-Uda antennas with the theoretical limit of all their elements being driven

2000 ◽  
Author(s):  
M.J. Underhill
Keyword(s):  
Theoretical Limit

New Aspects in the Design of Electron Optical Magnification Systems

1972 ◽  
Vol 30 ◽  
pp. 606-607
Author(s):  
Willem H.J. Andersen
Keyword(s):  
Electron Microscope ◽  
Imaging System ◽  
Chromatic Aberration ◽  
Research Tool ◽  
Energy Losses ◽  
Objective Lens ◽  
Theoretical Limit ◽  
Optical Magnification ◽  
Chromatic Aberrations ◽  
High Degree

Electron microscope design, and particularly the design of the imaging system, has reached a high degree of perfection. Present objective lenses perform up to their theoretical limit, while the whole imaging system, consisting of three or four lenses, provides very wide ranges of magnification and diffraction camera length with virtually no distortion of the image. Evolution of the electron microscope in to a routine research tool in which objects of steadily increasing thickness are investigated, has made it necessary for the designer to pay special attention to the chromatic aberrations of the magnification system (as distinct from the chromatic aberration of the objective lens). These chromatic aberrations cause edge un-sharpness of the image due to electrons which have suffered energy losses in the object.There exist two kinds of chromatic aberration of the magnification system; the chromatic change of magnification, characterized by the coefficient Cm, and the chromatic change of rotation given by Cp.

“Getting High Resolution Out of A High Voltage Microscope”

1980 ◽  
Vol 38 ◽  
pp. 822-825
Author(s):  
David J. Smith
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Voltage ◽  
Theoretical Limit ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Technological Advances ◽  
Potential Improvement ◽  
Lower Voltage

The initial attractions of the high voltage electron microscope (HVEM) stemmed mainly from the possibility of considerable increases in electron penetration through thick specimens compared with conventional 100KV microscopes, although the potential improvement in resolution associated with the decrease in election wavelength had been fully appreciated for many years (eg. Cosslett, 1946)1, even if not realizable in practice. Subsequent technological advances enabled the performance of lower voltage machines to be brought closer to the theoretical limit, to be followed in turn by more recent projects which have been successful, eventually, in achieving even higher resolution with dedicated higher voltage instruments such as those at Kyoto (500KV)2, Munich (400KV)3, Ibaraki (1250KV)4 and Cambridge (600KV)5. It does not necessarily follow however that the performance of journal high voltage microscopes can be easily upgraded, retrospectively, to the same level, as will be discussed in detail below.

scholarly journals Two-dimensional or passivation treatment: the effect of Hexylammonium post deposition treatment on 3D halide perovskite-based solar cells

2021 ◽  
Author(s):  
Stav Rahmany ◽  
Lioz Etgar
Keyword(s):  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Two Dimensional ◽  
Theoretical Limit ◽  
Halide Perovskite ◽  
Passivation Treatment ◽  
Post Deposition

Much effort has been made to push the power conversion efficiency of perovskite solar cells (PSCs) towards the theoretical limit. Recent studies have shown that post deposition treatment of barrier...

Biomass Pyrolysis in Sealed Vessels. Fixed-Carbon Yields from Avicel Cellulose That Realize the Theoretical Limit

2016 ◽  
Vol 30 (1) ◽  
pp. 480-491 ◽  
Author(s):  
Sam Van Wesenbeeck ◽  
Charissa Higashi ◽  
Maider Legarra ◽  
Liang Wang ◽  
Michael Jerry Antal
Keyword(s):  
Biomass Pyrolysis ◽  
Theoretical Limit ◽  
Fixed Carbon

Coupled Granular/Continuous Media – Results and Challenges

MRS Advances ◽  
2017 ◽  
Vol 2 (49) ◽  
pp. 2661-2668
Author(s):  
Horia Gavrila ◽  
Doina Elena Gavrila
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
Magnetic Recording ◽  
Granular Media ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Theoretical Limit ◽  
Perpendicular Recording ◽  
Perpendicular Magnetic Recording ◽  
Longitudinal Recording

ABSTRACTWhile the most promising longitudinal recording systems cannot surpass the theoretical limit of about 200 Gb/in2 for areal recording density and the demand for higher densities is permanently increasing, the perpendicular magnetic recording constitutes the realistic issue to the longitudinal one. The perpendicular magnetic recording offers significant advantages, the most important being stronger write and read fields, and therefore the use of media of higher anisotropy, smaller grain size, higher signal-to-noise ratio, and a better thermal stability. Unfortunately, the perpendicular recording has to cope some important physical and technological difficulties. To overcome them, many ingenious solutions were proposed. In this paper the coupled granular/continuous (CGC) media, a subtle association of the continuous and, respectively, granular media, are analysed from the viewpoint of their magnetic and recording properties. The challenges and possible improvements of CGC media are discussed.

scholarly journals Information Theoretical Limit of Media Forensics: The Forensicability

2016 ◽  
Vol 11 (4) ◽  
pp. 774-788 ◽  
Author(s):  
Xiaoyu Chu ◽  
Yan Chen ◽  
Matthew C. Stamm ◽  
K. J. Ray Liu
Keyword(s):  
Theoretical Limit ◽  
Media Forensics

Single-domain magnetically hard Sm2Co17 single crystals with magnetic energy equal to the theoretical limit

1979 ◽  
Vol 22 (6) ◽  
pp. 664-666
Author(s):  
A. V. Deryagin ◽  
E. A. Barabanova ◽  
N. V. Kudrevatykh ◽  
V. N. Moskalev
Keyword(s):  
Single Crystals ◽  
Magnetic Energy ◽  
Single Domain ◽  
Theoretical Limit ◽  
Magnetically Hard
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