Doubly-Charged Xe Ions Evidenced by Time Resolved RPA Measurement in the Far Field Plume of a Low-Power HET

2015 ◽  
Vol 55 (7) ◽  
pp. 529-537 ◽  
Author(s):  
T. Gibert ◽  
L. Balika ◽  
F. Diop ◽  
A. Bouchoule
Keyword(s):  
Low Power ◽  
Far Field ◽  
Time Resolved ◽  
Doubly Charged

Compact, Low-Power and Fully Reconfigurable 10 ps Resolution, 160 Range, Time-Resolved Single-Photon Counting System

2016 ◽  
Vol 16 (10) ◽  
pp. 3827-3833 ◽  
Author(s):  
Davide Tamborini ◽  
Mauro Buttafava ◽  
Alessandro Ruggeri ◽  
Franco Zappa
Keyword(s):  
Low Power ◽  
Single Photon ◽  
Photon Counting ◽  
Counting System ◽  
Time Resolved ◽  
Single Photon Counting

scholarly journals Numerical Prediction of Far-Field Combustion Noise from Aeronautical Engines

Acoustics ◽  
2019 ◽  
Vol 1 (1) ◽  
pp. 174-198 ◽  
Author(s):  
Mélissa Férand ◽  
Thomas Livebardon ◽  
Stéphane Moreau ◽  
Marlène Sanjosé
Keyword(s):  
Temperature Field ◽  
Low Power ◽  
Combustion Chamber ◽  
High Power ◽  
Acoustic Propagation ◽  
Combustion Noise ◽  
Far Field ◽  
Low Frequencies ◽  
Turboshaft Engine ◽  
Good Agreement

A hybrid methodology combining a detailed Large Eddy Simulation of a combustion chamber sector, an analytical propagation model of the extracted acoustic and entropy waves at the combustor exit through the turbine stages, and a far-field acoustic propagation through a variable exhaust temperature field was shown to predict far-field combustion noise from helicopter and aircraft propulsion systems accurately for the first time. For the single-stream turboshaft engine, the validation was achieved from engine core to the turbine exit. Propagation to the far field was then performed through a modeled axisymmetric jet. Its temperature modified the acoustic propagation of combustion noise significantly and a simple analytical model based on the Snell–Descarte law was shown to predict the directivity for axisymmetric single jet exhaust accurately. Good agreement with measured far-field spectra for all turboshaft-engine regimes below 2 kHz stresses that combustion noise is most likely the dominant noise source at low frequencies in such engines. For the more complex dual-stream turbofan engine, two regime computations showed that direct noise is mostly generated by the unsteady flame dynamics and the indirect combustion noise by the temperature stratification induced by the dilution holes in the combustion chamber, as found previously in the turboshaft case. However, in the turboengine, direct noise was found dominant at the combustor exit for the low power case and equivalent contributions of both combustion noise sources for the high power case. The propagation to the far-field was achieved through the temperature field provided by a Reynolds-Averaged Navier–Stokes simulation. Good agreement with measured spectra was also found at low frequencies for the low power turboengine case. At high power, however, turboengine jet noise overcomes combustion noise at low frequencies.

scholarly journals Low-Power Far-Field Wireless Powering for Wireless Sensors

2013 ◽  
Vol 101 (6) ◽  
pp. 1397-1409 ◽  
Author(s):  
Zoya Popovic ◽  
Erez Avigdor Falkenstein ◽  
Daniel Costinett ◽  
Regan Zane
Keyword(s):  
Low Power ◽  
Wireless Sensors ◽  
Far Field ◽  
Wireless Powering

Mechanisms of evolution of the propeller wake in the transition and far fields

2011 ◽  
Vol 682 ◽  
pp. 5-53 ◽  
Author(s):  
M. FELLI ◽  
R. CAMUSSI ◽  
F. DI FELICE
Keyword(s):  
Transition Region ◽  
Mutual Inductance ◽  
Transitional Region ◽  
Far Field ◽  
Time Resolved ◽  
Tip Vortices ◽  
Far Fields ◽  
Propeller Wake ◽  
Wake Instability ◽  
Blade Geometry

In the present study the mechanisms of evolution of propeller tip and hub vortices in the transitional region and the far field are investigated experimentally. The experiments involved detailed time-resolved visualizations and velocimetry measurements and were aimed at examining the effect of the spiral-to-spiral distance on the mechanisms of wake evolution and instability transition. In this regard, three propellers having the same blade geometry but different number of blades were considered. The study outlined dependence of the wake instability on the spiral-to-spiral distance and, in particular, a streamwise displacement of the transition region at the increasing inter-spiral distance. Furthermore, a multi-step grouping mechanism among tip vortices was highlighted and discussed. It is shown that such a phenomenon is driven by the mutual inductance between adjacent spirals whose characteristics change by changing the number of blades.

scholarly journals Real-time observation of a correlation-driven sub 3 fs charge migration in ionised adenine

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Erik P. Månsson ◽  
Simone Latini ◽  
Fabio Covito ◽  
Vincent Wanie ◽  
Mara Galli ◽  
...  
Keyword(s):  
Real Time ◽  
Charge Redistribution ◽  
Many Body ◽  
Charge Migration ◽  
Time Resolved ◽  
Molecular Reactivity ◽  
Time Observation ◽  
A Charge ◽  
Doubly Charged ◽  
Real Time Observation

AbstractSudden ionisation of a relatively large molecule can initiate a correlation-driven process dubbed charge migration, where the electron density distribution is expected to rapidly move along the molecular backbone. Capturing this few-femtosecond or attosecond charge redistribution would represent the real-time observation of electron correlation in a molecule with the enticing prospect of following the energy flow from a single excited electron to the other coupled electrons in the system. Here, we report a time-resolved study of the correlation-driven charge migration process occurring in the nucleic-acid base adenine after ionisation with a 15–35 eV attosecond pulse. We find that the production of intact doubly charged adenine – via a shortly-delayed laser-induced second ionisation event – represents the signature of a charge inflation mechanism resulting from many-body excitation. This conclusion is supported by first-principles time-dependent simulations. These findings may contribute to the control of molecular reactivity at the electronic, few-femtosecond time scale.

Time-resolved detection of far-field THz-radiation patterns: spatially restricted coherence of surface field THz emitters

1999 ◽  
Author(s):  
F. Hilbk-Kortenbruck ◽  
Peter H. Bolivar ◽  
Rainer Martini ◽  
Henricus P. M. Pellemans ◽  
Heinrich Kurz
Keyword(s):  
Thz Radiation ◽  
Far Field ◽  
Radiation Patterns ◽  
Time Resolved ◽  
Surface Field

scholarly journals Numerical Simulation of the Whole Thermal Lensing Process with Z-Scan-Based Methods Using Gaussian Beams

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5533
Author(s):  
Georges Boudebs
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Thermal Lensing ◽  
Gaussian Beams ◽  
Far Field ◽  
General Study ◽  
Temperature Estimation ◽  
Time Resolved ◽  
Thermal Phase ◽  
Order Of Magnitude

A general study of the diffracted far field due to thermal lens heating using Gaussian beams is presented. The numerical simulation considers the whole system, including both the optical and the thermal parameters. It is shown that the existing simplified relations found in the literature and used up to now only give the order of magnitude of the thermo-optical coefficients. More accurate, simplified formulas are derived to measure the induced thermal phase shift when working with Z-scan-based methods. Temperature estimation in absorbing media turn out to be more reliable whether using time-resolved or steady-state techniques. The extension of the calculation to the image formation in a 4f system is also addressed.

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