Ghost imaging in the frequency domain with a high brilliance coherent monochromatic source: a novel approach to extend spectroscopy sensitivity beyond detectors limits

Author(s):  
Marco Chiarini ◽  
Alberto Parini ◽  
Francesca Braglia ◽  
Lorella Braglia ◽  
Sandro Braglia ◽  
...  
Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7093
Author(s):  
Jie Cao ◽  
Dong Zhou ◽  
Fanghua Zhang ◽  
Huan Cui ◽  
Yingqiang Zhang ◽  
...  

Computational ghost imaging (CGI), with the advantages of wide spectrum, low cost, and robustness to light scattering, has been widely used in many applications. The key issue is long time correlations for acceptable imaging quality. To overcome the issue, we propose parallel retina-like computational ghost imaging (PRGI) method to improve the performance of CGI. In the PRGI scheme, sampling and reconstruction are carried out by using the patterns which are divided into blocks from designed retina-like patterns. Then, the reconstructed image of each block is stitched into the entire image corresponding to the object. The simulations demonstrate that the proposed PRGI method can obtain a sharper image while greatly reducing the time cost than CGI based on compressive sensing (CSGI), parallel architecture (PGI), and retina-like structure (RGI), thereby improving the performance of CGI. The proposed method with reasonable structure design and variable selection may lead to improve performance for similar imaging methods and provide a novel technique for real-time imaging applications.


Author(s):  
S. Arzanpour ◽  
N. Eslaminasab ◽  
B. Shubert ◽  
A. Narimani ◽  
M. F. Golnaraghi

In this paper, we examine a linear one degree of freedom engine mount to obtain optimum mount parameters in a passive configuration. An engine mount is a device that may be used to isolate vehicle body from the engine vibrations - forced excitation, while minimizing the effects of road-induced disturbances on the engine - base excitation. The linearity of the system allows us to analyze the frequency and time response characteristics in both excitation cases analytically. Optimal damping and stiffness values for the isolator are obtained by minimizing certain cost functions in the frequency and time domains, respectively. In the frequency domain the cost function is based on the root mean square (RMS) of the absolute acceleration and relative displacement in the frequency domain, and in the time domain it is based on the transmitted acceleration and displacement. The time and frequency responses of the isolator are optimized by varying the stiffness and damping ratios for both base and forced excitation cases. These optimal values are obtained, and the results are verified numerically. In this case, although the mathematical model is linear, it is interesting to note that the time and frequency optimal values are not the same. As a result, this exercise shows that no passive-mount is adequate to perfectly deal with all application specs and isolation criteria. In this paper, a novel approach is suggested to select the mount parameters for various passive or active configurations.


Geophysics ◽  
1996 ◽  
Vol 61 (3) ◽  
pp. 666-682 ◽  
Author(s):  
Michael S. Zhdanov ◽  
Peter Traynin ◽  
John R. Booker

A new method of the resistivity imaging based on frequency‐domain electromagnetic migration is developed. Electromagnetic (EM) migration involves downward diffusion of observed EM fields whose time flow has been reversed. Unlike downward analytical continuation, migration is a stable procedure that accurately restores the phase of the upgoing field inside the Earth. This method is indented for the processing and interpretation of EM data collected for both TE and TM modes of plane‐wave excitation. Until recently, the method could be applied only for determining the position of anomalous structures and for finding interfaces between layers of different conductivity. There were no well developed approaches to the resistivity imaging, which is the key problem in the inversion of EM data. We provide a novel approach to determining not only the position of anomalous structures but their resistivity as well. The main difficulty in the practical realization of this approach is determining the background resistivity distribution for migration. We discuss the method of the solution of this problem based on differential transformation of apparent resistivity curves. The final goal of migration is to provide a first order interpretation using a computational effort equivalent to a forward modeling calculation.


2012 ◽  
Vol 41 (13) ◽  
pp. 31-35
Author(s):  
H. B.Kekre ◽  
Archana B. Patankar ◽  
Aniruddh Munde ◽  
Disha Madhrani ◽  
Dheeraj Nagpal

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