Inverse Problems最新文献_第5页

Direct inversion of the Longitudinal ray transform for 2D residual elastic strain fields 直接反演二维残余弹性应变场的纵向射线变换

IF 2.1 2区数学

Inverse Problems Pub Date : 2024-06-17 DOI: 10.1088/1361-6420/ad52bb

C M Wensrich, S Holman, M Courdurier, W R B Lionheart, A P Polyakova and I E Svetov

引用次数: 0

A novel Newton method for inverse elastic scattering problems 用于反弹性散射问题的新型牛顿法

IF 2.1 2区数学

Inverse Problems Pub Date : 2024-06-11 DOI: 10.1088/1361-6420/ad4dda

Yan Chang, Yukun Guo, Hongyu Liu and Deyue Zhang

引用次数: 0

Reconstruction of inhomogeneous media by an iteration algorithm with a learned projector 利用迭代算法和学习投影器重建非均质介质

IF 2.1 2区数学

Inverse Problems Pub Date : 2024-06-10 DOI: 10.1088/1361-6420/ad4f0b

Kai Li, Bo Zhang, Haiwen Zhang

{"title":"Reconstruction of inhomogeneous media by an iteration algorithm with a learned projector","authors":"Kai Li, Bo Zhang, Haiwen Zhang","doi":"10.1088/1361-6420/ad4f0b","DOIUrl":"https://doi.org/10.1088/1361-6420/ad4f0b","url":null,"abstract":"This paper is concerned with the inverse problem of reconstructing an inhomogeneous medium from the acoustic far-field data at a fixed frequency in two dimensions. This inverse problem is severely ill-posed (and also strongly nonlinear), and certain regularization strategy is thus needed. However, it is difficult to select an appropriate regularization strategy which should enforce some <italic toggle=\"yes\">a priori</italic> information of the unknown scatterer. To address this issue, we plan to use a deep learning approach to learn some <italic toggle=\"yes\">a priori</italic> information of the unknown scatterer from certain ground truth data, which is then combined with a traditional iteration method to solve the inverse problem. Specifically, we propose a deep learning-based iterative reconstruction algorithm for the inverse problem, based on a repeated application of a deep neural network and the iteratively regularized Gauss–Newton method (IRGNM). Our deep neural network (called the learned projector in this paper) mainly focuses on learning the <italic toggle=\"yes\">a priori</italic> information of the <italic toggle=\"yes\">shape</italic> of the unknown contrast with a normalization technique in the training processes and is trained to act like a projector which is helpful for projecting the solution into some feasible region. Extensive numerical experiments show that our reconstruction algorithm provides good reconstruction results even for the high contrast case and has a satisfactory generalization ability.","PeriodicalId":50275,"journal":{"name":"Inverse Problems","volume":"63 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Feasibility of acousto-electric tomography 声电断层扫描的可行性

IF 2.1 2区数学

Inverse Problems Pub Date : 2024-06-03 DOI: 10.1088/1361-6420/ad4669

Bjørn Jensen, Adrian Kirkeby and Kim Knudsen

{"title":"Feasibility of acousto-electric tomography","authors":"Bjørn Jensen, Adrian Kirkeby and Kim Knudsen","doi":"10.1088/1361-6420/ad4669","DOIUrl":"https://doi.org/10.1088/1361-6420/ad4669","url":null,"abstract":"In acousto-electric tomography (AET) the goal is to reconstruct the electric conductivity in a domain from electrostatic boundary measurements of corresponding currents and voltages, while the domain is perturbed by a time-dependent acoustic wave, thus taking advantage of the acousto-electric effect. We approach the AET reconstruction in two steps: First, the interior power density is obtained from boundary measurements by solving a linear inverse and ill-posed problem; second, the interior conductivity is reconstructed from the power density by solving a non-linear and well-posed problem. Mathematically these inverse problems are fairly well understood, and reconstruction methods work well on synthetic data. This is in contrast to experimental findings. An effect can indeed be observed and data can be collected. However, the acousto-electric coupling is very weak, and consequently, the change in the measured voltage due to the acoustic perturbation might be too small compared to the background noise for viable reconstructions. In this paper, we take one step towards understanding the feasibility of AET. We provide an in-silico model of the coupled physics scenario based on standard models for the individual phenomena. Moreover, we formulate and implement numerically a full reconstruction method for the inverse problem via the two steps. We perform computational experiments with realistically chosen parameters from the context of medical imaging. The focus is on understanding the role of the acousto-electric coupling parameter and the signal-to-noise ratio (SNR). The critical signal strength is analyzed and the omnipresent Johnson–Nyquist noise is estimated. We obtain both positive and negative findings; we can reconstruct features even under severe noise conditions, but we also find that the SNR one is likely to face in practice is too low to obtain useful reconstructions.","PeriodicalId":50275,"journal":{"name":"Inverse Problems","volume":"14 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141252489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Effect of Electroconvulsive Therapy on Frontal QRS-T Angle in Psychiatric Patients. 电休克疗法对精神病患者额叶 QRS-T 角的影响

IF 1.1 2区数学

Inverse Problems Pub Date : 2024-05-29 eCollection Date: 2024-01-01 DOI: 10.29399/npa.28443

Ülker Atılan Fedai, Halil Fedai

{"title":"The Effect of Electroconvulsive Therapy on Frontal QRS-T Angle in Psychiatric Patients.","authors":"Ülker Atılan Fedai, Halil Fedai","doi":"10.29399/npa.28443","DOIUrl":"10.29399/npa.28443","url":null,"abstract":"Introduction: Electroconvulsive therapy (ECT) is one of the biological therapies that is well tolerated and has a low risk of complications. Acute cardiovascular complications related to ECT such as ventricular arrhythmia, myocardial infarction and cardiac arrest have been recorded. Increased frontal QRS-T (fQRS-T) angle was associated with ventricular arrhythmia, sudden cardiac death and total mortality. In this study, we aimed to evaluate the effect of ECT on the myocardium using electrocardiography (ECG) parameters such as fQRS-T angle, QRS duration, QT and QTc interval.Methods: A total of 108 patients diagnosed with bipolar disorder (n=36), depressive disorder (n=70) and schizophrenia (n=2) who underwent ECT were included in this study. 12-lead surface ECG of all patients were taken before the ECT, 15 min. after ECT and 24 hour after ECT.Results: QRS duration, QT interval and corrected QT (QTc) interval were not changed significantly during the follow-up period. However, we found that, fQRS-T angle was significantly increased 15 minutes after ECT compared to baseline angle (p<0.001). We also detected that this increase in fQRS-T angle 15 minutes after ECT was significantly reduced 24 hours after ECT (p=0.031). Meanwhile, there was no significant difference between baseline and 24th hour fQRS-T angle (p=0.154).Conclusions: In our study, a significant increase in fQRS-T angle was observed 15 min after ECT. However, the fQRS-T angle was found to return to normal after 24 hours. Our findings may indicate that ECT does not have a permanent side effect on the risk of cardiovascular events according to the fQRS-T angle.","PeriodicalId":50275,"journal":{"name":"Inverse Problems","volume":"27 1","pages":"135-140"},"PeriodicalIF":1.1,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11165600/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82794533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Inversion of the attenuated momenta ray transform of planar symmetric tensors 平面对称张量的衰减矩射线变换反演

IF 2.1 2区数学

Inverse Problems Pub Date : 2024-05-27 DOI: 10.1088/1361-6420/ad49cc

Hiroshi Fujiwara, David Omogbhe, Kamran Sadiq and Alexandru Tamasan

引用次数: 0

Inverse problem of recovering a time-dependent nonlinearity appearing in third-order nonlinear acoustic equations * 恢复三阶非线性声学方程中出现的随时间变化的非线性的逆问题 *

IF 2.1 2区数学

Inverse Problems Pub Date : 2024-05-23 DOI: 10.1088/1361-6420/ad49cd

Song-Ren Fu, Peng-Fei Yao and Yongyi Yu

引用次数: 0

Stability and statistical inversion of travel time tomography 旅行时间断层摄影的稳定性和统计反演