Time-Domain Fluorescence Molecular Tomography: A FEM-diffusion based Forward Model

2006 ◽  
Author(s):  
Feng GAO ◽  
Huijuan ZHAO ◽  
Yukari TANIKAWA ◽  
Andhi Marjono ◽  
Yukio YAMADA
Keyword(s):  
Time Domain ◽  
Forward Model ◽  
Fluorescence Molecular Tomography

scholarly journals Comparison of observed borehole temperatures in Antarctica with simulations using a forward model driven by climate model outputs covering the past millennium

2020 ◽  
Author(s):  
Zhiqiang Lyu ◽  
Anais J. Orsi ◽  
Hugues Goosse
Keyword(s):  
Surface Temperature ◽  
Antarctic Peninsula ◽  
Time Domain ◽  
Climate Model ◽  
Forward Model ◽  
Model Data ◽  
West Antarctica ◽  
Data Comparison ◽  
Borehole Temperature ◽  
The Time Domain

Abstract. The reconstructed surface temperature series from boreholes in Antarctica have significantly contributed to our understanding of centennial and multi-decadal temperature changes and thus provides us a good way to evaluate the climate model ability to reproduce low-frequency climate variability. However, up to now, there were no systematic model-data comparisons based on temperature from boreholes at regional or local scale in Antarctica. Here, we discuss two different ways to perform such a comparison using boreholes measurements and the corresponding reconstructions of surface temperature at West Antarctic Ice Sheet (WAIS), Larissa, Mill Island and Styx in Antarctica. The standard approach is to compare climate model outputs at the grid point closest to each site with the reconstructions in the time domain derived from the direct borehole temperature observations. Although some characteristics of the reconstructions, for instance the non-uniform smoothing, limit to some extent the model-data comparison, several robust features can be evaluated. In addition, a more direct model-data comparison based on the temperature measured in the boreholes is conducted using a forward model that simulates explicitly the subsurface temperature profiles when driven with climate model outputs. This comparison in the depth domain provides many consistent signals with those in the time domain, but also suggest some information that we cannot extract from the comparison in the time domain. The major results from these comparisons are used to define some metrics derived from the borehole temperature data for future model-data comparison, and demonstrate the spatial representativity of the sites chosen for the metrics. The long term cooling trend in West Antarctica from 1000 to 1600 CE (−1.0 °C) is generally reproduced by the models, but often with a weaker amplitude. The 19th century cooling in the Antarctic Peninsula (−0.94 °C) is not reproduced by any of the models, which tend to show warming instead. The trend over the last 50 years is generally well reproduced in West Antarctica and at Larissa (Antarctic Peninsula), but overestimated at other sites. The wide range of simulated trends indicates the importance of internal variability on the observed trends, and show the value of model-data comparison to investigate the response to forcings.

scholarly journals A Depth-recognizable Time-domain Fluorescence Molecular Tomography in Reflective Geometry

2021 ◽  
Author(s):  
Jiaju Cheng ◽  
PENG ZHANG ◽  
Chuangjian Cai ◽  
yang gao ◽  
Jie Liu ◽  
...  
Keyword(s):  
Time Domain ◽  
Fluorescence Molecular Tomography

Time-domain induced polarization forward modeling and an apparent spectral parameter solution based on the Weibull growth model

Geophysics ◽  
2020 ◽  
Vol 85 (5) ◽  
pp. D145-D155
Author(s):  
Qingxin Meng ◽  
Xiangyun Hu ◽  
Heping Pan ◽  
Huolin Ma ◽  
Miao Luo
Keyword(s):  
Growth Model ◽  
Time Domain ◽  
Forward Modeling ◽  
Induced Polarization ◽  
Forward Model ◽  
Model Parameters ◽  
Time Varying ◽  
Basic Algorithm ◽  
Cole Model ◽  
Physical Principles

The application of the Cole-Cole model within time-domain induced polarization (TDIP) forward field modeling shows that the model parameters can characterize time-varying states of the TDIP field and support observed data analysis. The Cole-Cole model contains real and imaginary parts, and it requires a frequency-to-time conversion for TDIP forward modeling. However, the TDIP field is usually expressed by a real number, and its intuitive time-varying states field intensity increases with charging time. Therefore, the forward model should be constructed in a simpler form. We have aimed to develop a forward model using mathematical functions not based on physical principles. The Weibull (WB) growth model, which is primarily used to describe the time-varying curve features in regression analysis, is introduced into the basic algorithm of the TDIP forward model. Subsequently, a forward expression of the TDIP effect is established. Based on the time-varying shape and scale parameters, this expression describes the time-varying rate and relaxation states of the TDIP fields. Furthermore, based on the extensively used conjugate gradient optimization, an apparent WB parameter scheme is initiated to calculate the spectral parameters that represent the relaxation and time-varying rate obtained from the multi-time-channel TDIP data. Finally, this scheme is applied to interpret the different simulated and actual TDIP data. The results demonstrate that the WB growth model can be used for the TDIP forward model without involving physical principles, the model parameters without specific physical significance can be used to represent the time-varying states of TDIP fields, and apparent WB parameters can be used to discern different TDIP observed data. The setting of the TDIP forward model and model parameters can actually be more flexible and diverse, so as to obtain simpler forward expressions and ensure a highly efficient inverse solution.

scholarly journals A linear, featured-data scheme for image reconstruction in time-domain fluorescence molecular tomography

2006 ◽  
Vol 14 (16) ◽  
pp. 7109 ◽  
Author(s):  
Feng Gao ◽  
Huijuan Zhao ◽  
Yukari Tanikawa ◽  
Yukio Yamada
Keyword(s):  
Image Reconstruction ◽  
Time Domain ◽  
Fluorescence Molecular Tomography ◽  
Data Scheme

scholarly journals Multimodal imaging combining time-domain near-infrared optical tomography and continuous-wave fluorescence molecular tomography

2020 ◽  
Vol 28 (7) ◽  
pp. 9860
Author(s):  
Wuwei Ren ◽  
Jingjing Jiang ◽  
Aldo Di Costanzo Mata ◽  
Alexander Kalyanov ◽  
Jorge Ripoll ◽  
...  
Keyword(s):  
Time Domain ◽  
Multimodal Imaging ◽  
Near Infrared ◽  
Continuous Wave ◽  
Optical Tomography ◽  
Fluorescence Molecular Tomography

Time-domain fluorescence molecular tomography based on experimental data

2009 ◽  
Author(s):  
Limin Zhang ◽  
Jiao Li ◽  
Feng Gao ◽  
Huiyuan He ◽  
Huijuan Zhao
Keyword(s):  
Experimental Data ◽  
Time Domain ◽  
Fluorescence Molecular Tomography

scholarly journals Comparison of observed borehole temperatures in Antarctica with simulations using a forward model driven by climate model outputs covering the past millennium

2020 ◽  
Vol 16 (4) ◽  
pp. 1411-1428
Author(s):  
Zhiqiang Lyu ◽  
Anais J. Orsi ◽  
Hugues Goosse
Keyword(s):  
Surface Temperature ◽  
Antarctic Peninsula ◽  
Time Domain ◽  
Climate Model ◽  
Forward Model ◽  
Model Data ◽  
West Antarctica ◽  
Data Comparison ◽  
Wide Range ◽  
The Time Domain

Abstract. The reconstructed surface-temperature time series from boreholes in Antarctica have significantly contributed to our understanding of multidecadal and centennial temperature changes and thus provide a good way to evaluate the ability of climate models to reproduce low-frequency climate variability. However, up to now, there has not been any systematic model–data comparison based on temperature from boreholes at a regional or local scale in Antarctica. Here, we discuss two different ways to perform such a comparison using borehole measurements and the corresponding reconstructions of surface temperature at the West Antarctic Ice Sheet (WAIS) Divide, Larissa, Mill Island, and Styx Glacier in Antarctica. The standard approach is to compare the surface temperature simulated by the climate model at the grid cell closest to each site with the reconstructions in the time domain derived from the borehole temperature observations. Although some characteristics of the reconstructions, for instance the nonuniform smoothing, limit to some extent the model–data comparison, several robust features can be evaluated. In addition, a more direct model–data comparison based on the temperature measured in the boreholes is conducted using a forward model that simulates explicitly the subsurface temperature profiles when driven with climate model outputs. This comparison in the depth domain is not only generally consistent with observations made in the time domain but also provides information that cannot easily be inferred from the comparison in the time domain. The major results from these comparisons are used to derive metrics that can be applied for future model–data comparison. We also describe the spatial representativity of the sites chosen for the metrics. The long-term cooling trend in West Antarctica from 1000 to 1600 CE (−1.0 ∘C) is generally reproduced by the models but often with a weaker amplitude. The 19th century cooling in the Antarctic Peninsula (−0.94 ∘C) is not reproduced by any of the models, which tend to show warming instead. The trend over the last 50 years is generally well reproduced in West Antarctica and at Larissa (Antarctic Peninsula) but overestimated at other sites. The wide range of simulated trends indicates the importance of internal variability in the observed trends and shows the value of model–data comparison to investigate the response to forcings.

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