Phase transitions and dielectric relaxations in superionic protonic conductor HUP (H3OUO2PO4.3H2O) in the broad frequency range (10-2-1010 Hz)

1987 ◽  
Vol 48 (8) ◽  
pp. 1325-1336 ◽  
Author(s):  
J.C. Badot ◽  
A. Fourrier-Lamer ◽  
N. Baffier ◽  
Ph. Colomban
Author(s):  
Noah H. Schiller ◽  
Sz-Chin Steven Lin ◽  
Randolph H. Cabell ◽  
Tony Jun Huang

This paper describes the design of a thin plate whose thickness is tailored in order to focus bending waves to a desired location on the plate. Focusing is achieved by smoothly varying the thickness of the plate to create a type of lens, which focuses structure-borne energy. Damping treatment can then be positioned at the focal point to efficiently dissipate energy with a minimum amount of treatment. Numerical simulations of both bounded and unbounded plates show that the design is effective over a broad frequency range, focusing traveling waves to the same region of the plate regardless of frequency. This paper also quantifies the additional energy dissipated by local damping treatment installed on a variable thickness plate relative to a uniform plate.


1985 ◽  
Vol 112 ◽  
pp. 405-410
Author(s):  
Edward T. Olsen ◽  
Anatoly Lokshin ◽  
Samuel Gulkis

One component of the NASA search for microwave signals of extraterrestrial intelligent origin will be an all sky survey at a significantly low limiting flux over a broad frequency range. We are currently designing an overall strategy which will permit this survey to be: (1) carried out using existing antennas in less than 3 years of observation time, (2) uniform in sensitivity (within 0.5 db) over the celestial sphere for any given frequency, and (3) complete to 6×10−23 W/m2 or better over the frequency range 1.2GHz⩽ν⩽10GHz with a frequency resolution of 32 Hz.


2020 ◽  
Vol 499 (3) ◽  
pp. 3434-3444
Author(s):  
Qian Zheng ◽  
Xiang-Ping Wu ◽  
Quan Guo ◽  
Melanie Johnston-Hollitt ◽  
Huanyuan Shan ◽  
...  

ABSTRACT The Square Kilometre Array (SKA) will be the first low-frequency instrument with the capability to directly image the structures of the epoch of reionization (EoR). Indeed, deep imaging of the EoR over five targeted fields of 20 sq deg each has been selected as the highest priority science objective for SKA1. Aiming at preparing for this highly challenging observation, we perform an extensive pre-selection of the ‘quietest’ and ‘cleanest’ candidate fields in the southern sky to be suited for deep imaging of the EoR using existing catalogues and observations over a broad frequency range. The candidate fields should meet a number of strict criteria to avoid contaminations from foreground structures and sources. The candidate fields should also exhibit both the lowest average surface brightness and smallest variance to ensure uniformity and high-quality deep imaging over the fields. Our selection eventually yields a sample of 7 ‘ideal’ fields of 20 sq deg in the southern sky that could be targeted for deep imaging of the EoR. Finally, these selected fields are convolved with the synthesized beam of SKA1-low stations to ensure that the effect of sidelobes from the far-field bright sources is also weak.


1983 ◽  
Vol 23 (2) ◽  
pp. 158-164 ◽  
Author(s):  
G. M. Smith ◽  
R. L. Bierman ◽  
S. J. Zitek

2011 ◽  
Author(s):  
Koen Vansant ◽  
Rapha\agl Hallez ◽  
Hadrien B\aeriot ◽  
Michel Tournour ◽  
Gert Massa ◽  
...  

2011 ◽  
Vol 279 ◽  
pp. 49-53
Author(s):  
Yu Сhao Li ◽  
Xiang Сai Ge ◽  
Sie Chin Tjong

The dielectric relaxation behavior of poly (vinylidene fluoride) based composites filled with beta silicon carbide nanoparticles were investigated over a wide frequency range and temperature intervals. The composites exhibited dielectric relaxations in the tested frequency range and the relaxations of composites can be well described via the modulus formalism of dielectric spectroscopy. Further, activation energy determined from the isothermal dielectric relaxations tended to decrease with increasing SiC indicating the promotion of SiC to the dipole relaxations of PVDF.


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