A method to eliminate the matching problem and improve the spectral property of Talbot spectrometer

2022 ◽  
Vol 148 ◽  
pp. 106755
Author(s):  
Yixuan Li ◽  
Yu Huang ◽  
Haochen Li ◽  
Xiaohu Yang ◽  
Zhanfeng Li ◽  
...  
2009 ◽  
Vol 35 (2) ◽  
pp. 186-192 ◽  
Author(s):  
Zhi-Bo TIAN ◽  
Li-Xin TANG ◽  
Yi-Ming REN ◽  
Yong-Ming ZHAO ◽  
Cheng-Xin WU
Keyword(s):  

2018 ◽  
pp. 48-52
Author(s):  
S. V. Popov ◽  
G. N. Devyatkov

When designing radioelectronic devices, that are included in the composition of various systems, it is important to solve broadband matching problem and filtering problem. However, usually these problems are separated and not considered together. Moreover, the synthesis of filters does not take into account the behavior of impedances of the generator and the load in the stopbands. The solution of the complex problem is actual, since it allows expanding the functionality of the device, which can greatly simplify the construction of the radio engineering product. It should be noted that in the known literature solution of this problem in such a formulation is not considered. The aim of the work is to develop a synthesis method and algorithm of broadband devices that connect arbitrary immitances of the generator and the load, and these devices should perform simultaneously functions of both matching and filtering in reactive lumped electric element base and in distributed electric element base, limited only by transmission lines with T-waves. In this paper, a two-stage automated method of synthesis presented here stage allows at the first to adequately find a good initial solution to the posed problem (determining structure and parameters of the broadband matching and filtering quadrupole), in the second stage this approach allows to find the optimal solution to the complex problem, taking into account the constraints on physical and circuit realizability. In this work, the synthesis of broadband matching and filtering devices in lumped and distributed electrical element basis is carried out, and these devices connect complex impedances of the source and the load. The characteristics of the devices obtained after the synthesis show that the solution of the complex problem of matching and filtering gives a significant improvement in filtering properties with small losses in the level of transmitted power.


Electronics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 65
Author(s):  
Quan Zhao ◽  
Ling Tong ◽  
Bo Gao

The classical two-channel push-pull chirp transform spectrometer (CTS) has been widely applied in satellite-borne remote sensing systems for earth observation and deep space exploration. In this paper, we present two simplified structures with single M(l)-C(s) CTS arrangements for the spectral analysis of stationary signals. A simplified CTS system with a single M(l)-C(s) arrangement and a time delay line was firstly developed. Another simplified structure of CTS with a M(l)-C(s) arrangement and a frequency conversion channel was also developed for spectral analysis of stationary signals. Simulation and experiment results demonstrate that the two simplified arrangements can both realize spectrum measurement for the stationary signals and obtain the same frequency resolution, amplitude accuracy and system sensitivity as that of the classical two-channel push–pull CTS system. Compared to the classical CTS structure, the two simplified arrangements require fewer devices, save power consumption and have reduced mass. The matching problem between the two channels can be avoided in the two simplified arrangements. The simplified CTS arrangements may have potential application in the spectrum measurement of stationary signals in the field of aviation and spaceflight.


Author(s):  
Geir Evensen

AbstractIt is common to formulate the history-matching problem using Bayes’ theorem. From Bayes’, the conditional probability density function (pdf) of the uncertain model parameters is proportional to the prior pdf of the model parameters, multiplied by the likelihood of the measurements. The static model parameters are random variables characterizing the reservoir model while the observations include, e.g., historical rates of oil, gas, and water produced from the wells. The reservoir prediction model is assumed perfect, and there are no errors besides those in the static parameters. However, this formulation is flawed. The historical rate data only approximately represent the real production of the reservoir and contain errors. History-matching methods usually take these errors into account in the conditioning but neglect them when forcing the simulation model by the observed rates during the historical integration. Thus, the model prediction depends on some of the same data used in the conditioning. The paper presents a formulation of Bayes’ theorem that considers the data dependency of the simulation model. In the new formulation, one must update both the poorly known model parameters and the rate-data errors. The result is an improved posterior ensemble of prediction models that better cover the observations with more substantial and realistic uncertainty. The implementation accounts correctly for correlated measurement errors and demonstrates the critical role of these correlations in reducing the update’s magnitude. The paper also shows the consistency of the subspace inversion scheme by Evensen (Ocean Dyn. 54, 539–560 2004) in the case with correlated measurement errors and demonstrates its accuracy when using a “larger” ensemble of perturbations to represent the measurement error covariance matrix.


2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Daniel Vert ◽  
Renaud Sirdey ◽  
Stéphane Louise

AbstractThis paper experimentally investigates the behavior of analog quantum computers as commercialized by D-Wave when confronted to instances of the maximum cardinality matching problem which is specifically designed to be hard to solve by means of simulated annealing. We benchmark a D-Wave “Washington” (2X) with 1098 operational qubits on various sizes of such instances and observe that for all but the most trivially small of these it fails to obtain an optimal solution. Thus, our results suggest that quantum annealing, at least as implemented in a D-Wave device, falls in the same pitfalls as simulated annealing and hence provides additional evidences suggesting that there exist polynomial-time problems that such a machine cannot solve efficiently to optimality. Additionally, we investigate the extent to which the qubits interconnection topologies explains these latter experimental results. In particular, we provide evidences that the sparsity of these topologies which, as such, lead to QUBO problems of artificially inflated sizes can partly explain the aforementioned disappointing observations. Therefore, this paper hints that denser interconnection topologies are necessary to unleash the potential of the quantum annealing approach.


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