Full‐polarisation three‐dimensional pattern synthesis for conformal conical arrays with dynamic range ratio constraint by using the initialisations based on equivalence theorem

2015 ◽  
Vol 9 (15) ◽  
pp. 1659-1666 ◽  
Author(s):  
Yunxiang Zhang ◽  
Zhiqin Zhao ◽  
Zaiping Nie ◽  
Qing Huo Liu
Keyword(s):  
Dynamic Range ◽  
Three Dimensional ◽  
Equivalence Theorem ◽  
Pattern Synthesis

scholarly journals An Improved Pattern Synthesis Iterative Method in Planar Arrays for Obtaining Efficient Footprints with Arbitrary Boundaries

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2358
Author(s):  
Aarón Ángel Salas-Sánchez ◽  
Cibrán López-Álvarez ◽  
Juan Antonio Rodríguez-González ◽  
María Elena López-Martín ◽  
Francisco José Ares-Pena
Keyword(s):  
Dynamic Range ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Test Cases ◽  
Pattern Synthesis ◽  
Maximum Order ◽  
Space Applications ◽  
Planar Arrays ◽  
Aperture Distribution

In the present paper, an iterative technique devoted to reproducing efficient footprints with arbitrary boundaries for planar arrays is addressed. The methodology here depicted is based on exploiting the nature of the continuous aperture distribution by expressing it as a Fourier series of moderately high orders. In this manner, the resulting illumination boundary is defined by a target three-dimensional flat-topped pattern composed of stretching and shrinking modified circular Taylor patterns and the maximum order of the series to obtain a good reconstruction is determined by means of the iterative process. Examples and comparisons with the previous literature were conducted by analyzing square and rectangular contoured beams as test cases. Additionally, interesting potentials regarding space applications from a geostationary satellite are outlined by means of the EuTELSAT (European Telecommunications Satellite Organization) European coverage case study. In such a way, its numerical approach was analyzed by including subarray architectures and discussing improvements about dynamic range ratio of the excitations without critical power losses within the illumination region.

Foundations of Advanced Neuroanatomy: Technical Guidelines for Specimen Preparation, Dissection, and 3D-Photodocumentation in a Surgical Anatomy Laboratory

2019 ◽  
Author(s):  
Luciano César PC Leonel ◽  
Lucas P. Carlstrom ◽  
Christopher S. Graffeo ◽  
Avital Perry ◽  
Carlos Diogenes Pinheiro-Neto ◽  
...  
Keyword(s):  
Oral Tradition ◽  
Dynamic Range ◽  
Tap Water ◽  
Three Dimensional ◽  
High Dynamic Range ◽  
Surgical Anatomy ◽  
Lessons Learned ◽  
Specimen Preparation ◽  
Technological Advances ◽  
Key Steps

Abstract Objective This study was aimed to provide a key update to the seminal works of Prof. Albert L. Rhoton Jr., MD, with particular attention to previously unpublished insights from the oral tradition of his fellows, recent technological advances including endoscopy, and high-dynamic range (HDR) photodocumentation, and, local improvements in technique, we have developed to optimize efficient neuroanatomic study. Methods Two formaldehyde-fixed cadaveric heads were injected with colored latex to demonstrate step-by-step specimen preparation for microscopic or endoscopic dissection. One formaldehyde-fixed brain was utilized to demonstrate optimal three-dimensional (3D) photodocumentation techniques. Results Key steps of specimen preparation include vessel cannulation and securing, serial tap water flushing, specimen drainage, vessel injection with optimized and color-augmented latex material, and storage in 70% ethanol. Optimizations for photodocumentation included the incorporation of dry black drop cloth and covering materials, an imaging-oriented approach to specimen positioning and illumination, and single-camera stereoscopic capture techniques, emphasizing the three-exposure-times-per-eye approach to generating images for HDR postprocessing. Recommended tools, materials, and technical nuances were emphasized throughout. Relative advantages and limitations of major 3D projection systems were comparatively assessed, with sensitivity to audience size and purpose specific recommendations. Conclusion We describe the first consolidated step-by-step approach to advanced neuroanatomy, including specimen preparation, dissection, and 3D photodocumentation, supplemented by previously unpublished insights from the Rhoton fellowship experience and lessons learned in our laboratories in the past years such that Prof. Rhoton's model can be realized, reproduced, and expanded upon in surgical neuroanatomy laboratories worldwide.

scholarly journals Ab initiostructure determination of nanocrystals of organic pharmaceutical compounds by electron diffraction at room temperature using a Timepix quantum area direct electron detector

2016 ◽  
Vol 72 (2) ◽  
pp. 236-242 ◽  
Author(s):  
E. van Genderen ◽  
M. T. B. Clabbers ◽  
P. P. Das ◽  
A. Stewart ◽  
I. Nederlof ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Room Temperature ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Direct Methods ◽  
Liquid Nitrogen Temperature ◽  
High Dynamic Range ◽  
Electron Diffraction Data ◽  
High Signal

Until recently, structure determination by transmission electron microscopy of beam-sensitive three-dimensional nanocrystals required electron diffraction tomography data collection at liquid-nitrogen temperature, in order to reduce radiation damage. Here it is shown that the novel Timepix detector combines a high dynamic range with a very high signal-to-noise ratio and single-electron sensitivity, enablingab initiophasing of beam-sensitive organic compounds. Low-dose electron diffraction data (∼0.013 e− Å−2 s−1) were collected at room temperature with the rotation method. It was ascertained that the data were of sufficient quality for structure solution using direct methods using software developed for X-ray crystallography (XDS,SHELX) and for electron crystallography (ADT3D/PETS,SIR2014).

scholarly journals First multispacecraft ion measurements in and near the Earth’s magnetosphere with the identical Cluster ion spectrometry (CIS) experiment

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1303-1354 ◽  
Author(s):  
H. Rème ◽  
C. Aoustin ◽  
J. M. Bosqued ◽  
I. Dandouras ◽  
B. Lavraud ◽  
...  
Keyword(s):  
Solar Wind ◽  
Angular Resolution ◽  
Dynamic Range ◽  
Ion Beam ◽  
Three Dimensional ◽  
Charge Composition ◽  
Ion Distribution ◽  
Central Plasma ◽  
Cluster Ion ◽  
High Level

Abstract. On board the four Cluster spacecraft, the Cluster Ion Spectrometry (CIS) experiment measures the full, three-dimensional ion distribution of the major magnetospheric ions (H+, He+, He++, and O+) from the thermal energies to about 40 keV/e. The experiment consists of two different instruments: a COmposition and DIstribution Function analyser (CIS1/CODIF), giving the mass per charge composition with medium (22.5°) angular resolution, and a Hot Ion Analyser (CIS2/HIA), which does not offer mass resolution but has a better angular resolution (5.6°) that is adequate for ion beam and solar wind measurements. Each analyser has two different sensitivities in order to increase the dynamic range. First tests of the instruments (commissioning activities) were achieved from early September 2000 to mid January 2001, and the operation phase began on 1 February 2001. In this paper, first results of the CIS instruments are presented showing the high level performances and capabilities of the instruments. Good examples of data were obtained in the central plasma sheet, magnetopause crossings, magnetosheath, solar wind and cusp measurements. Observations in the auroral regions could also be obtained with the Cluster spacecraft at radial distances of 4–6 Earth radii. These results show the tremendous interest of multispacecraft measurements with identical instruments and open a new area in magnetospheric and solar wind-magnetosphere interaction physics.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetopheric configuration and dynamics; solar wind - magnetosphere interactions)

scholarly journals Adaptive Binocular Fringe Dynamic Projection Method for High Dynamic Range Measurement

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 4023 ◽  
Author(s):  
Changzhi Yu ◽  
Fang Ji ◽  
Junpeng Xue ◽  
Yajun Wang
Keyword(s):  
Projection Method ◽  
Dynamic Range ◽  
Three Dimensional ◽  
High Dynamic Range ◽  
Fringe Projection ◽  
Range Measurement ◽  
Optimal Projection ◽  
Three Dimensional Measurement ◽  
High Dynamic ◽  
Adaptively Adjusting

Three-dimensional measurement with fringe projection sensor has been commonly researched. However, the measurement accuracy and efficiency of most fringe projection sensors are still seriously affected by image saturation and the non-linear effects of the projector. In order to solve the challenge, in conjunction with the advantages of stereo vision technology and fringe projection technology, an adaptive binocular fringe dynamic projection method is proposed. The proposed method can avoid image saturation by adaptively adjusting the projection intensity. Firstly, the flowchart of the proposed method is explained. Then, an adaptive optimal projection intensity method based on multi-threshold segmentation is introduced to adjust the projection illumination. Finally, the mapping relationship of binocular saturation point and projection point is established by binocular transformation and left camera–projector mapping. Experiments demonstrate that the proposed method can achieve higher accuracy for high dynamic range measurement.

Power Gain Pattern Synthesis of Array Antenna With Dynamic Range Ratio Restriction

2019 ◽  
pp. 1-1 ◽  
Author(s):  
Shiwen Lei ◽  
Haoquan Hu ◽  
Pu Tang ◽  
Bo Chen ◽  
Jing Tian ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Array Antenna ◽  
Power Gain ◽  
Pattern Synthesis

CT Multiscan: Using Small Area Detectors to Image Large Components

1995 ◽  
Author(s):  
E. A. Sivers ◽  
W. A. Ellingson ◽  
S. A. Snyder ◽  
D. A. Holloway
Keyword(s):  
Small Area ◽  
Dynamic Range ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Large Component ◽  
X Ray ◽  
Area Detector ◽  
Longest Path ◽  
Ceramic Components ◽  
X Ray Computed

The small size and dynamic range of the best two-dimensional X-ray detectors are impediments to the use of three-dimensional X-ray computed tomography (3D-XRCT) for 100% inspection of large ceramic components. The most common industrial 3D-XRCT systems use a “rotate-only” geometry in which the X-ray source and the area detector remain stationary while the component placed between them is rotated through 360°. This configuration offers the highest inspection speed and the best utilization of X-ray dose, but requires that the component be small enough to fit within the X-ray/detector “cone.” Also, if the object is very dense, the ratio of an unattenuated X-ray signal to that through the longest path in the component may exceed the dynamic range of the detector. To some extent, both of these disadvantages can be overcome by using “Multiscan CT,” i.e., scanning small overlapping regions of a large component separately while maximizing the X-ray dose to each. The overlapping scans can then be combined seamlessly into a single scan with optimal contrast.

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