Recent Developments in Ultra-Wideband Sources and Antennas

2003 ◽  
pp. 369-379 ◽  
Author(s):  
William D. Prather ◽  
Carl E. Baum ◽  
Jane M. Lehr ◽  
Robert J. Torres ◽  
Tyrone C. Tran ◽  
...  
Keyword(s):  
Ultra Wideband ◽  
Recent Developments

scholarly journals A Review on Graphene-Based Light Emitting Functional Devices

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4217
Author(s):  
Muhammad Junaid ◽  
M. H. Md Khir ◽  
Gunawan Witjaksono ◽  
Zaka Ullah ◽  
Nelson Tansu ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Ultra Wideband ◽  
Optical Modulators ◽  
Active Materials ◽  
Linear Dispersion ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Theoretical Investigations ◽  
Recent Developments ◽  
Potential Applications

In recent years, the field of nanophotonics has progressively developed. However, constant demand for the development of new light source still exists at the nanometric scale. Light emissions from graphene-based active materials can provide a leading platform for the development of two dimensional (2-D), flexible, thin, and robust light-emitting sources. The exceptional structure of Dirac’s electrons in graphene, massless fermions, and the linear dispersion relationship with ultra-wideband plasmon and tunable surface polarities allows numerous applications in optoelectronics and plasmonics. In this article, we present a comprehensive review of recent developments in graphene-based light-emitting devices. Light emissions from graphene-based devices have been evaluated with different aspects, such as thermal emission, electroluminescence, and plasmons assisted emission. Theoretical investigations, along with experimental demonstration in the development of graphene-based light-emitting devices, have also been reviewed and discussed. Moreover, the graphene-based light-emitting devices are also addressed from the perspective of future applications, such as optical modulators, optical interconnects, and optical sensing. Finally, this review provides a comprehensive discussion on current technological issues and challenges related to the potential applications of emerging graphene-based light-emitting devices.

Recent Developments in Ultra-Wideband Sources and Antennas

2005 ◽  
pp. 393-397 ◽  
Author(s):  
William D. Prather ◽  
Carl E. Baum ◽  
Jane M. Lehr ◽  
Robert J. Torres ◽  
Tyrone C. Tran ◽  
...  
Keyword(s):  
Ultra Wideband ◽  
Recent Developments

scholarly journals Ultra-Wideband Networking

2021 ◽  
pp. 565-569
Author(s):  
Prachi Kandalkar
Keyword(s):  
Narrow Band ◽  
Broad Band ◽  
Wide Band ◽  
Ultra Wideband ◽  
Ultra Wide Band ◽  
Future Change ◽  
Wireless Applications ◽  
Advantages And Disadvantages ◽  
The World ◽  
Recent Developments

Ultra broad band (UWB) has emerged as a leading technology for potential wireless applications due to recent developments in wideband impulse technology, low power and communication. When opposed to traditional narrow band networks, ultra-wide band (UWB) wireless communications takes a completely different approach to wireless communication. The technology is generating a lot of buzz around the world. This paper outlines the characteristics, its applications, and advantages and disadvantages. It main focuses on the future change of UWB.

scholarly journals Recent developments in simulation-driven multi-objective design of antennas

2015 ◽  
Vol 63 (3) ◽  
pp. 781-789
Author(s):  
S. Koziel ◽  
A. Bekasiewicz
Keyword(s):  
Ultra Wideband ◽  
Kriging Interpolation ◽  
High Fidelity ◽  
Simulation Data ◽  
Simulation Accuracy ◽  
Multi Objective ◽  
Advantages And Disadvantages ◽  
Recent Developments ◽  
Response Correction ◽  
Em Simulation

Abstract This paper addresses computationally feasible multi-objective optimization of antenna structures. We review two recent techniques that utilize the multi-objective evolutionary algorithm (MOEA) working with fast antenna replacement models (surrogates) constructed as Kriging interpolation of coarse-discretization electromagnetic (EM) simulation data. The initial set of Pareto-optimal designs is subsequently refined to elevate it to the high-fidelity EM simulation accuracy. In the first method, this is realized point-by-point through appropriate response correction techniques. In the second method, sparsely sampled high-fidelity simulation data is blended into the surrogate model using Co-kriging. Both methods are illustrated using two design examples: an ultra-wideband (UWB) monocone antenna and a planar Yagi-Uda antenna. Advantages and disadvantages of the methods are also discussed.

scholarly journals Uncertainty Characterisation of Mobile Robot Localisation Techniques using Optical Surveying Grade Instruments

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2274 ◽  
Author(s):  
Benjamin McLoughlin ◽  
Harry Pointon ◽  
John McLoughlin ◽  
Andy Shaw ◽  
Frederic Bezombes
Keyword(s):  
Ground Truth ◽  
Position Estimation ◽  
Ultra Wideband ◽  
Optimal Position ◽  
Total Station ◽  
Positioning Systems ◽  
Recent Developments ◽  
Sensor Measurement ◽  
Uncertainty Models ◽  
Robotic Total Station

Recent developments in localisation systems for autonomous robotic technology have been a driving factor in the deployment of robots in a wide variety of environments. Estimating sensor measurement noise is an essential factor when producing uncertainty models for state-of-the-art robotic positioning systems. In this paper, a surveying grade optical instrument in the form of a Trimble S7 Robotic Total Station is utilised to dynamically characterise the error of positioning sensors of a ground based unmanned robot. The error characteristics are used as inputs into the construction of a Localisation Extended Kalman Filter which fuses Pozyx Ultra-wideband range measurements with odometry to obtain an optimal position estimation, all whilst using the path generated from the remote tracking feature of the Robotic Total Station as a ground truth metric. Experiments show that the proposed method yields an improved positional estimation compared to the Pozyx systems’ native firmware algorithm as well as producing a smoother trajectory.

Trends in Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 228-229
Author(s):  
C. Colliex ◽  
P. Trebbia
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Analytical Technique ◽  
Recent Developments ◽  
Quantitative Results ◽  
Electron Microscopes ◽  
Electron Energy Loss ◽  
Primary Electrons

The physical foundations for the use of electron energy loss spectroscopy towards analytical purposes, seem now rather well established and have been extensively discussed through recent publications. In this brief review we intend only to mention most recent developments in this field, which became available to our knowledge. We derive also some lines of discussion to define more clearly the limits of this analytical technique in materials science problems.The spectral information carried in both low ( 0<ΔE<100eV ) and high ( >100eV ) energy regions of the loss spectrum, is capable to provide quantitative results. Spectrometers have therefore been designed to work with all kinds of electron microscopes and to cover large energy ranges for the detection of inelastically scattered electrons (for instance the L-edge of molybdenum at 2500eV has been measured by van Zuylen with primary electrons of 80 kV). It is rather easy to fix a post-specimen magnetic optics on a STEM, but Crewe has recently underlined that great care should be devoted to optimize the collecting power and the energy resolution of the whole system.

Filaments and membranes in the mitotic apparatus

1983 ◽  
Vol 41 ◽  
pp. 544-547
Author(s):  
Kent McDonald
Keyword(s):  
Intermediate Filaments ◽  
Mitotic Spindle ◽  
Mitotic Apparatus ◽  
Light Microscope Level ◽  
Microtubule Associated Proteins ◽  
Recent Developments ◽  
Associated Proteins ◽  
Force Generator ◽  
Spindle Function ◽  
Antibody Technology

At the light microscope level the recent developments and interest in antibody technology have permitted the localization of certain non-microtubule proteins within the mitotic spindle, e.g., calmodulin, actin, intermediate filaments, protein kinases and various microtubule associated proteins. Also, the use of fluorescent probes like chlorotetracycline suggest the presence of membranes in the spindle. Localization of non-microtubule structures in the spindle at the EM level has been less rewarding. Some mitosis researchers, e.g., Rarer, have maintained that actin is involved in mitosis movements though the bulk of evidence argues against this interpretation. Others suggest that a microtrabecular network such as found in chromatophore granule movement might be a possible force generator but there is little evidence for or against this view. At the level of regulation of spindle function, Harris and more recently Hepler have argued for the importance of studying spindle membranes. Hepler also believes that membranes might play a structural or mechanical role in moving chromosomes.

Software pattern recognition applied to nanodiffraction patterns from a STEM instrument

1986 ◽  
Vol 44 ◽  
pp. 694-695
Author(s):  
G.Y. Fan ◽  
J.M. Cowley
Keyword(s):  
Image Processing ◽  
Pattern Recognition ◽  
Computer Software ◽  
Processing System ◽  
Light Level ◽  
Host Computer ◽  
Low Light ◽  
Image Processing System ◽  
Recent Developments ◽  
On Line

In recent developments, the ASU HB5 has been modified so that the timing, positioning, and scanning of the finely focused electron probe can be entirely controlled by a host computer. This made the asynchronized handshake possible between the HB5 STEM and the image processing system which consists of host computer (PDP 11/34), DeAnza image processor (IP 5000) which is interfaced with a low-light level TV camera, array processor (AP 400) and various peripheral devices. This greatly facilitates the pattern recognition technique initiated by Monosmith and Cowley. Software called NANHB5 is under development which, instead of employing a set of photo-diodes to detect strong spots on a TV screen, uses various software techniques including on-line fast Fourier transform (FFT) to recognize patterns of greater complexity, taking advantage of the sophistication of our image processing system and the flexibility of computer software.

High-resolution microscopy of twin boundaries in gold

1987 ◽  
Vol 45 ◽  
pp. 260-261
Author(s):  
William Krakow ◽  
David A. Smith
Keyword(s):  
High Resolution ◽  
Specimen Preparation ◽  
Gold Films ◽  
Boundary Area ◽  
Transmission Electron ◽  
Recent Developments ◽  
Tilt Boundaries ◽  
High Resolution Microscopy ◽  
Twist Boundaries

Recent developments in specimen preparation, imaging and image analysis together permit the experimental determination of the atomic structure of certain, simple grain boundaries in metals such as gold. Single crystal, ∼125Å thick, (110) oriented gold films are vapor deposited onto ∼3000Å of epitaxial silver on (110) oriented cut and polished rock salt substrates. Bicrystal gold films are then made by first removing the silver coated substrate and placing in contact two suitably misoriented pieces of the gold film on a gold grid. Controlled heating in a hot stage first produces twist boundaries which then migrate, so reducing the grain boundary area, to give mixed boundaries and finally tilt boundaries perpendicular to the foil. These specimens are well suited to investigation by high resolution transmission electron microscopy.

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