scholarly journals From scattering theory to complex wave dynamics in non-Hermitian PT -symmetric resonators

2013 ◽  
Vol 371 (1989) ◽  
pp. 20120194 ◽  
Author(s):  
Henning Schomerus
Keyword(s):  
Scattering Theory ◽  
Single Channel ◽  
Multiple Wave ◽  
Wave Dynamics ◽  
Complex Eigenvalues ◽  
Complex Wave ◽  
Energy Domain ◽  
Multiple Wave Scattering ◽  
The Time Domain ◽  
Time And Energy

I review how methods from mesoscopic physics can be applied to describe the multiple wave scattering and complex wave dynamics in non-Hermitian -symmetric resonators, where an absorbing region is coupled symmetrically to an amplifying region. Scattering theory serves as a convenient tool to classify the symmetries beyond the single-channel case and leads to effective descriptions that can be formulated in the energy domain (via Hamiltonians) and in the time domain (via time evolution operators). These models can then be used to identify the mesoscopic time and energy scales that govern the spectral transition from real to complex eigenvalues. The possible presence of magneto-optical effects (a finite vector potential) in multi-channel systems leads to a variant (termed symmetry) that imposes the same spectral constraints as symmetry. I also provide multi-channel versions of generalized flux-conservation laws.

scholarly journals A Multi-Class Automatic Sleep Staging Method Based on Photoplethysmography Signals

Entropy ◽  
2021 ◽  
Vol 23 (1) ◽  
pp. 116
Author(s):  
Xiangfa Zhao ◽  
Guobing Sun
Keyword(s):  
Time Domain ◽  
Single Channel ◽  
Kappa Statistic ◽  
Gradient Boosting ◽  
Sleep Staging ◽  
Challenging Problem ◽  
Sleep State ◽  
Light Gradient ◽  
Gradient Boosting Machine ◽  
The Time Domain

Automatic sleep staging with only one channel is a challenging problem in sleep-related research. In this paper, a simple and efficient method named PPG-based multi-class automatic sleep staging (PMSS) is proposed using only a photoplethysmography (PPG) signal. Single-channel PPG data were obtained from four categories of subjects in the CAP sleep database. After the preprocessing of PPG data, feature extraction was performed from the time domain, frequency domain, and nonlinear domain, and a total of 21 features were extracted. Finally, the Light Gradient Boosting Machine (LightGBM) classifier was used for multi-class sleep staging. The accuracy of the multi-class automatic sleep staging was over 70%, and the Cohen’s kappa statistic k was over 0.6. This also showed that the PMSS method can also be applied to stage the sleep state for patients with sleep disorders.

Application of Population-Based Techniques to Identification of Diffusive and Convective Parameters in Timber Drying

2021 ◽  
Vol 412 ◽  
pp. 163-176
Author(s):  
Kerolyn L. Holek ◽  
Paulo S.B. Zdanski ◽  
Miguel Vaz Jr.
Keyword(s):  
Inverse Problem ◽  
Process Parameters ◽  
Moisture Transfer ◽  
Transfer Problem ◽  
Wood Properties ◽  
Population Based ◽  
Optimization Techniques ◽  
The Time Domain ◽  
Coupled Solution ◽  
Time And Energy

Timber drying consists of reducing the moisture content up to a level required by the intended application of the wood product. A proper drying operation is essential to reduce time and energy, as well as to prevent defects. Numerical simulation of this class of problems constitutes an important tool available to the process engineer to define the best drying schedule. However, a successful prediction requires knowledge of the wood properties and additional process parameters. This work is inserted within this framework and aims at discussing strategies do determine material and process parameters using inverse problem techniques. The timber drying process accounts for the fully coupled solution of the heat and mass (moisture) transfer problem, whereas the inverse problem is solved within the time domain based on population-based optimization techniques.

scholarly journals All-optical attosecond time domain interferometry

2020 ◽  
Author(s):  
Zhen Yang ◽  
Wei Cao ◽  
Yunlong Mo ◽  
Huiyao Xu ◽  
Kang Mi ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Time Domain ◽  
Optical Pulse ◽  
Precision Measurements ◽  
Optical Interferometer ◽  
Transition Dipole ◽  
Interferometric Technique ◽  
All Optical ◽  
Energy Domain ◽  
Time And Energy

Abstract Interferometry, a key technique in modern precision measurements, has been used for length measurement in engineering metrology and astronomy. An analogous time-domain interferometric technique would represent a significant complement to spatial domain applications and require the manipulation of interference on extreme time and energy scales. Here, we report an all-optical interferometer using laser-driven high order harmonics as attosecond temporal slits. By controlling the phase of the temporal slits with an external field, a time domain interferometer that preserves attosecond temporal and hundreds of meV energy resolution is implemented. We apply this exceptional temporal resolution to reconstruct the waveform of an arbitrarily polarized optical pulse, and utilize the provided energy resolution to interrogate the abnormal character of the transition dipole near the Cooper minimum in argon. This novel attosecond interferometry paves the way for high precision measurements in the time energy domain using all-optical approaches.

Multiple wave scattering from fractal aggregates

2004 ◽  
Vol 19 (2) ◽  
pp. 421-425 ◽  
Author(s):  
Gabor Korvin ◽  
Klavdia Oleschko
Keyword(s):  
Wave Scattering ◽  
Fractal Aggregates ◽  
Multiple Wave ◽  
Multiple Wave Scattering

scholarly journals Enhancement of Single-Channel Periodic Signals in the Time-Domain

2012 ◽  
Vol 20 (7) ◽  
pp. 1948-1963 ◽  
Author(s):  
Jesper Rindom Jensen ◽  
Jacob Benesty ◽  
Mads Græsbøll Christensen ◽  
Søren Holdt Jensen
Keyword(s):  
Time Domain ◽  
Single Channel ◽  
Periodic Signals ◽  
The Time Domain
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