scholarly journals A Fast Tomographic Reconstruction Method for Flame Temperature Distribution Measurement Based on Direct Solution Algorithm

2021 ◽  
Vol 9 ◽  
Author(s):  
Biao Zhang ◽  
Wei-Jian Peng ◽  
Jian Li ◽  
Zhi-Hao Li ◽  
Chuan-Long Xu
Keyword(s):  
Temperature Distribution ◽  
Least Squares ◽  
Structural Characteristics ◽  
Flame Temperature ◽  
Solution Algorithm ◽  
Qr Factorization ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Direct Solution ◽  
Reconstruction Algorithms

The rapid and accurate measurement of the flame temperature distribution is of great significance to the structural design and health diagnosis of the engine. Aiming at the low reconstruction efficiency of traditional flame temperature distribution reconstruction algorithms, a Direct Solution algorithm for flame temperature distribution reconstruction is proposed in this paper based on the structural characteristics of the reconstruction equations. By setting several numerical cases, the performance of the Direct Solution algorithm and some commonly used traditional algorithms, such as Simultaneous Algebraic Reconstruction Technique (SART), Least Squares QR-factorization (LSQR) algorithm, Non-Negative Least Squares QR-factorization (NNLS) algorithm, is compared in the reconstruction of the flame temperature distribution. The results show that the efficiency of the Direct Solution method is 169.4, 7.4, and 3483.3 times higher than that of the SART, LSQR, and NNLS algorithms under the condition of 40 × 40 grids. In addition, with the increase of the number of grids, the growth rate of the reconstruction time of the Direct Solution algorithm is much lower than that of other algorithms. The overall reconstruction accuracy of the Direct Solution algorithm is better than that of SART and LSQR algorithms. This shows that it has an excellent comprehensive performance and has a great application prospect in the rapid reconstruction of the temperature distribution.

BIFURCATION ANALYSIS OF ITERATIVE IMAGE RECONSTRUCTION METHOD FOR COMPUTED TOMOGRAPHY

2008 ◽  
Vol 18 (04) ◽  
pp. 1219-1225 ◽  
Author(s):  
TETSUYA YOSHINAGA ◽  
YOSHIHIRO IMAKURA ◽  
KEN'ICHI FUJIMOTO ◽  
TETSUSHI UETA
Keyword(s):  
Computed Tomography ◽  
Image Reconstruction ◽  
Computational Method ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Algebraic Reconstruction Technique ◽  
Reconstruction Algorithms ◽  
Iterative Image Reconstruction ◽  
Multiplicative Algebraic Reconstruction Technique ◽  
Algebraic Reconstruction

Of the iterative image reconstruction algorithms for computed tomography (CT), the power multiplicative algebraic reconstruction technique (PMART) is known to have good properties for speeding convergence and maximizing entropy. We analyze here bifurcations of fixed and periodic points that correspond to reconstructed images observed using PMART with an image made of multiple pixels and we investigate an extended PMART, which is a dynamical class for accelerating convergence. The convergence process for the state in the neighborhood of the true reconstructed image can be reduced to the property of a fixed point observed in the dynamical system. To investigate the speed of convergence, we present a computational method of obtaining parameter sets in which the given real or absolute values of the characteristic multiplier are equal. The advantage of the extended PMART is verified by comparing it with the standard multiplicative algebraic reconstruction technique (MART) using numerical experiments.

Alternative pulmonary artery reconstruction technique in the arterial switch operation

2021 ◽  
Author(s):  
Hisayuki Hongu ◽  
Masaaki Yamagishi ◽  
Yoshinobu Maeda ◽  
Keiichi Itatani ◽  
Masatoshi Shimada ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Arterial Switch Operation ◽  
Late Complication ◽  
Late Complications ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Arterial Switch ◽  
Switch Operation ◽  
Longitudinal Extension

Abstract OBJECTIVES Late complications of arterial switch operations (ASO) for transposition of the great arteries, such as neo-pulmonary artery (PA) stenosis and/or neoaortic regurgitation, have been reported. We developed an alternative reconstruction method called the longitudinal extension (LE) method to prevent PA bifurcation stenosis (PABS). METHODS We identified 48 patients diagnosed with transposition of the great arteries and performed ASO using the Lecompte manoeuvre for neo-PA reconstruction. In 9 consecutive patients (from 2014), the LE method was performed (LE). Before 2014, conventional techniques were performed in 39 patients (C). The median body weight and age in the LE and C groups were 3.0 and 3.1 kg and 12 and 26 days, respectively. In the LE group, 1 patient underwent bilateral PA banding before ASO. In C, PA banding and arch repair were performed in 1 patient each. Patients who received concomitant procedures were included. RESULTS The median follow-up in LE and C groups was 1.9 and 10.1 years, respectively. Early mortality/late death was not found in group LE and in 1 patient in group C. Only 1 case required ascending aorta sliding plasty in LE, and 8 patients needed PA augmentation for PABS in C. The median velocity of right/left PA was measured as 1.6/1.9 m/s in LE and 2.1/2.3 m/s in C, so it showed a lower value in LE. CONCLUSIONS Excellent mid-term results were obtained with the LE method. It was considered a useful procedure in preventing PABS, which is a primary late complication of ASO. Further follow-up and investigations are needed.

scholarly journals Fractional Differential Equation-Based Instantaneous Frequency Estimation for Signal Reconstruction

2021 ◽  
Vol 5 (3) ◽  
pp. 83
Author(s):  
Bilgi Görkem Yazgaç ◽  
Mürvet Kırcı
Keyword(s):  
Differential Equation ◽  
Fractional Differential Equation ◽  
Frequency Estimation ◽  
Signal Reconstruction ◽  
Reconstruction Method ◽  
Reconstruction Algorithms ◽  
Instantaneous Frequency Estimation ◽  
Proposed Model ◽  
Fractional Differential ◽  
Instantaneous Frequencies

In this paper, we propose a fractional differential equation (FDE)-based approach for the estimation of instantaneous frequencies for windowed signals as a part of signal reconstruction. This approach is based on modeling bandpass filter results around the peaks of a windowed signal as fractional differential equations and linking differ-integrator parameters, thereby determining the long-range dependence on estimated instantaneous frequencies. We investigated the performance of the proposed approach with two evaluation measures and compared it to a benchmark noniterative signal reconstruction method (SPSI). The comparison was provided with different overlap parameters to investigate the performance of the proposed model concerning resolution. An additional comparison was provided by applying the proposed method and benchmark method outputs to iterative signal reconstruction algorithms. The proposed FDE method received better evaluation results in high resolution for the noniterative case and comparable results with SPSI with an increasing iteration number of iterative methods, regardless of the overlap parameter.

A Bounded Variation Approach to Inverse Interferometry

1995 ◽  
Author(s):  
B. G. Fitzpatrick ◽  
S. L. Keeling ◽  
S. G. Rock
Keyword(s):  
Least Squares ◽  
Flow Measurement ◽  
Optical Methods ◽  
Optical Data ◽  
Reconstruction Technique ◽  
Direct Inversion ◽  
Variation Approach ◽  
Mathematical Techniques ◽  
Traditional Approaches ◽  
Least Squares Techniques

Abstract A least squares reconstruction technique is examined for determining flow-field densities from optical data. Nonintrusive optical methods have long been used for flow visualization; however, the goal of this work is to devise mathematical techniques with which optical data can be used for quantitative flow measurement. The ill-posedness of density computation from interferogram measurements is recognized as a serious limitation in direct inversion methods. Here, least squares techniques employing compactness constraints are developed to avoid the difficulties encountered in traditional approaches.

scholarly journals Source reconstruction for bioluminescence tomography via L1∕2 regularization

2018 ◽  
Vol 11 (02) ◽  
pp. 1750014 ◽  
Author(s):  
Jingjing Yu ◽  
Qiyue Li ◽  
Haiyu Wang
Keyword(s):  
Image Quality ◽  
Matching Pursuit ◽  
Imaging Modality ◽  
Reconstruction Algorithm ◽  
Reconstruction Method ◽  
Reconstruction Algorithms ◽  
Preclinical Research ◽  
Bioluminescence Tomography ◽  
Comparison Results ◽  
Stable Reconstruction

Bioluminescence tomography (BLT) is an important noninvasive optical molecular imaging modality in preclinical research. To improve the image quality, reconstruction algorithms have to deal with the inherent ill-posedness of BLT inverse problem. The sparse characteristic of bioluminescent sources in spatial distribution has been widely explored in BLT and many L1-regularized methods have been investigated due to the sparsity-inducing properties of L1 norm. In this paper, we present a reconstruction method based on L[Formula: see text] regularization to enhance sparsity of BLT solution and solve the nonconvex L[Formula: see text] norm problem by converting it to a series of weighted L1 homotopy minimization problems with iteratively updated weights. To assess the performance of the proposed reconstruction algorithm, simulations on a heterogeneous mouse model are designed to compare it with three representative sparse reconstruction algorithms, including the weighted interior-point, L1 homotopy, and the Stagewise Orthogonal Matching Pursuit algorithm. Simulation results show that the proposed method yield stable reconstruction results under different noise levels. Quantitative comparison results demonstrate that the proposed algorithm outperforms the competitor algorithms in location accuracy, multiple-source resolving and image quality.

scholarly journals Augmenting Signaling Pathway Reconstructions

2020 ◽  
Author(s):  
Tobias Rubel ◽  
Anna Ritz
Keyword(s):  
Signaling Pathways ◽  
Signaling Pathway ◽  
Protein Interactions ◽  
Cellular Response ◽  
Ground Truth ◽  
Protein Interaction Data ◽  
Reconstruction Method ◽  
Reconstruction Algorithms ◽  
Molecular Systems ◽  
Pathway Reconstruction

AbstractSignaling pathways drive cellular response, and understanding such pathways is fundamental to molecular systems biology. A mounting volume of experimental protein interaction data has motivated the development of algorithms to computationally reconstruct signaling pathways. However, existing methods suffer from low recall in recovering protein interactions in ground truth pathways, limiting our confidence in any new predictions for experimental validation. We present the Pathway Reconstruction AUGmenter (PRAUG), a higher-order function for producing high-quality pathway reconstruction algorithms. PRAUG modifies any existing pathway reconstruction method, resulting in augmented algorithms that outperform their un-augmented counterparts for six different algorithms across twenty-nine diverse signaling pathways. The algorithms produced by PRAUG collectively reveal potential new proteins and interactions involved in the Wnt and Notch signaling pathways. PRAUG offers a valuable framework for signaling pathway prediction and discovery.

Combustion Optimization for the ALSTOM GT13E2 Gas Turbine

2006 ◽  
Author(s):  
Ch. Steinbach ◽  
N. Ulibarri ◽  
M. Garay ◽  
H. Lu¨bcke ◽  
Th. Meeuwissen ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Flame Temperature ◽  
Air Entrainment ◽  
Flame Stabilization ◽  
Flame Stability ◽  
Nox Emissions ◽  
Combustion Control ◽  
Control Logic ◽  
The Individual ◽  
Combustion Optimization

The NOx emissions of low NOx premix combustors are not only determined by the burner design, but also by the multi burner interaction and the related distribution of air and fuel flows to the individual burners. Often the factors that have a positive impact on NOx emission have a negative impact on the flame stability, so the main challenge is to find an optimum point with the lowest achievable NOx while maintaining good flame stability. The hottest flame zones are where most of the NOx is formed. Avoiding such zones in the combustor (by homogenization of the flame temperature) reduces NOx emissions significantly. Improving the flame stability and the combustion control allows the combustor to operate at a lower average flame temperature and NOx emissions. ALSTOM developed a combustion optimization package for the GT13E2. The optimization package development focused on three major issues: • Flame stability; • Homogenization of flame temperature distribution in the combustor; • Combustion control logic. The solution introduced consists of: • The reduction of cooling air entrainment in the primary flame zone for improved flame stability; • The optical measurement of the individual burner flame temperatures and their homogenization by burner tuning valves; • Closed loop control logic to control the combustion dependent on the pulsation signal. This paper shows how fundamental combustion research methods were applied to derive effective optimization measures. The flame temperature measurement technique will be presented along with results of the measurement and their application in homogenization of the combustor temperature distribution in an engine equipped with measures to improve flame stabilization. The main results achieved are: • Widening of the main burner group operation range; • Improved use of the low NOx operation range; • NOx reduction at the combustor pulsation limit and hence, large margins to the European emission limit (50 mg/m3 @ 15%O2).

Non-intrusive Load Monitoring Based on the Graph Least Squares Reconstruction Method

2021 ◽  
pp. 1-1
Author(s):  
Xiaoyang Ma ◽  
Diwen Zheng ◽  
Ying Wang ◽  
Yang Wang ◽  
Hong Luo
Keyword(s):  
Least Squares ◽  
Reconstruction Method ◽  
Load Monitoring
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