scholarly journals ALMA Band-to-band Phase Referencing: Imaging Capabilities on Long Baselines and High Frequencies

2020 ◽  
Vol 160 (2) ◽  
pp. 59
Author(s):  
Yoshiharu Asaki ◽  
Luke T. Maud ◽  
Edward B. Fomalont ◽  
William R. F. Dent ◽  
Loreto Barcos-Muñoz ◽  
...  
Keyword(s):  
High Frequencies ◽  
Long Baselines

Quasi-Periodic Oscillations in Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 77-88
Author(s):  
Edward L. Robinson
Keyword(s):  
Binary Systems ◽  
Outer Edge ◽  
Light Curves ◽  
Close Binary ◽  
Bright Spot ◽  
Dwarf Novae ◽  
Periodic Oscillations ◽  
High Frequencies ◽  
Short Period ◽  
Typical Time

Three distinct kinds of rapid variations have been detected in the light curves of dwarf novae: rapid flickering, short period coherent oscillations, and quasi-periodic oscillations. The rapid flickering is seen in the light curves of most, if not all, dwarf novae, and is especially apparent during minimum light between eruptions. The flickering has a typical time scale of a few minutes or less and a typical amplitude of about .1 mag. The flickering is completely random and unpredictable; the power spectrum of flickering shows only a slow decrease from low to high frequencies. The observations of U Gem by Warner and Nather (1971) showed conclusively that most of the flickering is produced by variations in the luminosity of the bright spot near the outer edge of the accretion disk around the white dwarf in these close binary systems.

ОСОБЕННОСТИ ПРОЕКТИРОВАНИЯ СВЧ-КЛЮЧЕЙ В РАЗНЫХ КОНСТРУКТИВНО-ТЕХНОЛОГИЧЕСКИХ БАЗИСАХ

2020 ◽  
Vol 96 (3s) ◽  
pp. 627-630
Author(s):  
А.Д. Калёнов ◽  
И.И. Мухин ◽  
В.В. Репин
Keyword(s):  
High Frequencies ◽  
Basic Parameters ◽  
Parasitic Effects ◽  
Soi Cmos

Представляется сравнение СВЧ-ключей, проектируемых в разных конструктивно-технологических базисах: КНИ, КМОП, биполярные и GaAs. Определенные трудности существуют при разработке ключей на сверхвысоких частотах, в разных технологиях необходимо учитывать различные эффекты. Наличие паразитных эффектов сильно осложняет разработку. В статье приводится оценка влияния паразитных эффектов на основные параметры СВЧ-ключей в разных конструктивно-технологических базисах. The paper offers a comparison of microwave keys designed in different structural and technological bases: SOI, CMOS, bipolar and GaAs. There are some difficulties in developing the keys to the ultra-high frequencies, in different technologies it is necessary to consider various effects. The presence of parasitic effects greatly complicates the development. The article provides an assessment of the influence of parasitic effects on the basic parameters of microwave keys in different structural and technological bases.

Signal Processing Enhanced Fiber Vibration Sensors

2013 ◽  
Vol 543 ◽  
pp. 302-305
Author(s):  
Daniele Tosi ◽  
Massimo Olivero ◽  
Alberto Vallan ◽  
Guido Perrone
Keyword(s):  
Signal Processing ◽  
Optical Fibers ◽  
Adaptive Filters ◽  
Spectral Estimation ◽  
Cost Effective ◽  
Fiber Sensors ◽  
High Frequencies ◽  
Vibration Sensors ◽  
Signal Processing Algorithms ◽  
Plastic Optical Fibers

The paper analyzes the feasibility of cost-effective fiber sensors for the measurement of small vibrations, from low to medium-high frequencies, in which the complexity of the measurement is moved from expensive optics to cheap electronics without losing too much performance thanks to signal processing algorithms. Two optical approaches are considered: Bragg gratings in standard telecom fibers, which represent the most common type of commercial fiber sensors, and specifically developed sensors made with plastic optical fibers. In both cases, to keep the overall cost low, vibrations are converted into variations of the light intensity, although this makes the received signal more sensitive to noise. Then, adaptive filters and advanced spectral estimation techniques are used to mitigate noise and improve the sensitivity. Preliminary results have demonstrated that the combined effect of these techniques can yield to a signal-to-noise improvement of about 30 dB, bringing the proposed approaches to the level of the most performing sensors for the measurement of vibrations.

scholarly journals A systematic review on the effect of low-dose radiation on hearing

2021 ◽  
Author(s):  
Srikanth Nayak ◽  
Arivudai Nambi ◽  
Sathish Kumar ◽  
P Hariprakash ◽  
Pradeep Yuvaraj ◽  
...  
Keyword(s):  
Systematic Review ◽  
Ionizing Radiation ◽  
Radiation Exposure ◽  
Low Dose ◽  
Behavioral Symptoms ◽  
National Council ◽  
Low Dose Radiation ◽  
Cochlear Function ◽  
High Frequencies ◽  
Dose Radiation

AbstractNumerous studies have documented the adverse effects of high-dose radiation on hearing in patients. On the other hand, radiographers are exposed to a low dose of ionizing radiation, and the effect of a low dose of radiation on hearing is quite abstruse. Therefore, the present systematic review aimed to elucidate the effect of low-dose ionizing radiation on hearing. Two authors independently carried out a comprehensive data search in three electronic databases, including PUBMED/MEDLINE, CINAHL, and SCOPUS. Eligible articles were independently assessed for quality by two authors. Cochrane Risk of Bias tool was used assess quality of the included studies. Two articles met the low-dose radiation exposure criteria given by Atomic Energy Regulatory Board (AERB) and National Council on Radiation Protection (NCRP) guidelines. Both studies observed the behavioral symptoms, pure-tone hearing sensitivity at the standard, extended high frequencies, and the middle ear functioning in low-dose radiation-exposed individuals and compared with age and gender-matched controls. One study assessed the cochlear function using transient-evoked otoacoustic emissions (TEOAE). Both studies reported that behavioral symptoms of auditory dysfunction and hearing thresholds at extended high frequencies were higher in radiation-exposed individuals than in the controls. The current systematic review concludes that the low-dose ionizing radiation may affect the hearing adversely. Nevertheless, further studies with robust research design are required to explicate the cause and effect relationship between the occupational low-dose ionizing radiation exposure and hearing.

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