scholarly journals New electrical tomographic method to determine dampness in historical buildings

2016 ◽  
Vol 65 (2) ◽  
pp. 273-283 ◽  
Author(s):  
Tomasz Rymarczyk ◽  
Przemysław Adamkiewicz ◽  
Karol Duda ◽  
Jakub Szumowski ◽  
Jan Sikora
Keyword(s):  
Inverse Problem ◽  
Nondestructive Method ◽  
Forward Model ◽  
Laboratory Model ◽  
Brick Wall ◽  
Historical Buildings ◽  
Topological Methods ◽  
Wall Structures ◽  
Gradient Technique ◽  
Tomographic Method

Abstract This paper presents a new, nondestructive method of testing brick wall dampness in wall structures. The setup was used to determine the moisture in a specially built laboratory model. Topological methods and the gradient technique are used to optimize the approach. A forward model of a wall was constructed to solve the inverse problem resulting in moisture buildup inside the wall.

scholarly journals Monitoring of Thermal and Moisture Processes in Various Types of External Historical Walls

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 505 ◽  
Author(s):  
Dariusz Bajno ◽  
Lukasz Bednarz ◽  
Zygmunt Matkowski ◽  
Krzysztof Raszczuk
Keyword(s):  
Masonry Wall ◽  
Design Guidelines ◽  
Masonry Walls ◽  
Historical Buildings ◽  
Wall Structures ◽  
Mutual Comparison ◽  
Energy Audits ◽  
Biological Corrosion ◽  
Comfort Parameters ◽  
The Impact

In order to create and make available the following: Design guidelines, recommendations for energy audits, data for analysis and simulation of the condition of masonry walls susceptible to biological corrosion, deterioration of comfort parameters in rooms, or deterioration of thermal resistance, the article analyzes various types of masonry wall structures occurring in and commonly used in historical buildings over the last 200 years. The summary is a list of results of particular types of masonry walls and their mutual comparison. On this basis, a procedure path has been proposed which is useful for monitoring heat loss, monitoring the moisture content of building partitions, and improving the hygrothermal comfort of rooms. The durability of such constructions has also been estimated and the impact on the condition of the buildings that have been preserved and are still in use today was assessed.

scholarly journals Extraction of Weak Scatterer Features Based on Multipath Exploitation in Radar Imagery

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Muhannad Almutiry ◽  
Lorenzo Lo Monte ◽  
Michael C. Wicks
Keyword(s):  
Inverse Problem ◽  
Model Simulation ◽  
Forward Model ◽  
Secondary Source ◽  
Scene Modeling ◽  
Scattering Effects ◽  
Measurement Domain ◽  
Radar Imagery ◽  
Nonlinear Matrix ◽  
Multipath Scattering

We proposed an improved solution to two problems. The first problem is caused by the sidelobe of the dominant scatterer masking a weak scatterer. The proposed solution is to suppress the dominant scatterer by modeling its electromagnetic effects as a secondary source or “extra dependent transmitter” in the measurement domain. The suppression of the domain scatterer reveals the presence of the weak scatterer based on exploitation of multipath effects. The second problem is linearizing the mathematical forward model in the measurement domain. Improving the quantity of the prediction, including multipath scattering effects (neglected under the Born approximation), allows us to solve the inverse problem. The multiple bounce (multipath) scattering effect is the interaction of more than one target in the scene. Modeling reflections from one target towards another as a transmitting dipole will add the multiple scattering effects to the scattering field and permit us to solve a linear inverse problem without sophisticated solutions of a nonlinear matrix in the forward model. Simulation results are presented to validate the concept.

scholarly journals Reconstruction of Depolarization Pattern in Myocardial Infarction Cases Using Two Cascaded Stages of Artificial Neural Networks

2021 ◽  
Vol 2128 (1) ◽  
pp. 012016
Author(s):  
Nihal A. Mabrouk ◽  
Abdelreheem M. Khalifa ◽  
Abdelmenem A. Nasser ◽  
Moustafa H. Aly
Keyword(s):  
Myocardial Infarction ◽  
Neural Networks ◽  
Inverse Problem ◽  
Artificial Neural Networks ◽  
Electrical Activity ◽  
Heart Diseases ◽  
Three Dimensional ◽  
The Body ◽  
Forward Model ◽  
Artificial Neural

Abstract Our paper introduces a new technique for diagnosis of various heart diseases without the need of highly experts to investigate the electrocardiogram (ECG). Using the same electrodes of the ECG machine, it will be able to transmit directly the electrical activity inside the heart to a moving picture. Our technique is based on artificial intelligence algorithm using artificial neural networks (ANN). Finding the trans-membrane potential (TMP) inside the heart from the body surface potential (BSP) is known as the inverse problem of ECG. To have a unique solution for the inverse problem the data used should be obtained from a forward model. A three dimensional (3-D) model of cellular activation whole heart embedded in torso is simulated and solved using COMSOL Multiphysics software. In our previous paper, one ANN succeeded in displaying the wave propagation on the surface of a normal heart. In this paper, we used a configuration of ANNs to display different cases of heart with myocardial infarction (MI). To check the system accuracy, eight MI cases with different sizes and locations in the heart are simulated in the forward model. This configuration proved to be highly accurate in displaying each MI case -size and location- presenting the infarction as an area with no electrical activity.

scholarly journals Frequency Shifting Model for Diffuse Optical Tomography

2021 ◽  
Author(s):  
Huseyin Ozgur Kazanci
Keyword(s):  
Inverse Problem ◽  
Frequency Domain ◽  
Continuous Wave ◽  
Model Problem ◽  
Optical Tomography ◽  
Diffuse Optical Tomography ◽  
Solution Space ◽  
Forward Model ◽  
Problem Solution ◽  
Frequency Shifting

Abstract Diffuse Optical Tomography (DOT) imaging technique has been interesting research field for researchers since it has uncertainties in the solution space. DOT modality is unsolved scientific problem. Inverse problem solution and image reconstruction has never been in its best quality. Reconstructed images have low spatial resolution. Scattering nature of diffusive light is the obscuring effect for DOT modality. DOT has 3 functional sub-branches which of these are Continuous Wave (CW), Time-Resolved (TR), and Frequency-Domain (FD). In this work, one new approach to Frequency Domain Diffuse Optical Tomography (FDDOT) biomedical optic imaging modality is presented to the readers. Frequency Shifting data were added to the forward model problem which basically has source-detector couplings and number of imaging voxels. 100 MHz center core light modulation frequency was selected. 169 source-detector matches were used on back-reflected imaging geometry. Absorption coefficient ma was selected 0.1 cm− 1. Scattering coefficient µs was selected 100 cm− 1. 1 micrometer x, y, z cartesian grid coordinates were used in each direction for imaging tissue-like simulation media. The total of 100 frequency shift was added to the forward model problem which has 5 Hz frequency step. 2 inclusion objects were embedded inside the imaging simulation phantom. 2 inclusion images were successfully reconstructed with the low contrast to noise ratio (CNR) error and position error (PE). Frequency shifting technique is first applied for FDDOT here. This technique has increased the total number of equations in the forward model problem; hence it is helping to solve the inverse problem. In this work, the positive effect of using multi frequency methodology was observed. Differentiation of 2 embedded inclusions was successfully completed and illustrated in this work.

scholarly journals NONDESTRUCTIVE METHOD TO DETERMINE MOISTURE AREA IN HISTORICAL BUILDING

2017 ◽  
Vol 7 (1) ◽  
pp. 68-71 ◽  
Author(s):  
Tomasz Rymarczyk ◽  
Przemysław Adamkiewicz
Keyword(s):  
Finite Element Method ◽  
Sensitivity Analysis ◽  
Finite Element ◽  
Nondestructive Method ◽  
Brick Wall ◽  
Building Structures ◽  
The Finite Element Method ◽  
Historical Building ◽  
One Step ◽  
Real Building

This paper presents a nondestructive method of brick wall dampness testing in real building structures. The proposed algorithm was used to determine the moisture of test brick walls on the specially models. The finite element method has been used to solve the forward problem. The algorithm is initialized by using one step methods and topological sensitivity analysis. There was constructed the forward model and solved the inverse for visualization of moisture inside objects.

scholarly journals Analysis of the Impact of Model Nonlinearities in Inverse Problem Solving

2008 ◽  
Vol 65 (9) ◽  
pp. 2803-2823 ◽  
Author(s):  
T. Vukicevic ◽  
D. Posselt
Keyword(s):  
Inverse Problem ◽  
Numerical Analysis ◽  
Probability Density ◽  
Prior Knowledge ◽  
Nonlinear Model ◽  
Model Error ◽  
Forward Model ◽  
Time Space ◽  
Analysis Technique ◽  
The Impact

Abstract In this study, the relationship between nonlinear model properties and inverse problem solutions is analyzed using a numerical technique based on the inverse problem theory formulated by Mosegaard and Tarantola. According to this theory, the inverse problem and solution are defined via convolution and conjunction of probability density functions (PDFs) that represent stochastic information obtained from the model, observations, and prior knowledge in a joint multidimensional space. This theory provides an explicit analysis of the nonlinear model function, together with information about uncertainties in the model, observations, and prior knowledge through construction of the joint probability density, from which marginal solution functions can then be evaluated. The numerical analysis technique derived from the theory computes the component PDFs in discretized form via a combination of function mapping on a discrete grid in the model and observation phase space and Monte Carlo sampling from known parametric distributions. The efficacy of the numerical analysis technique is demonstrated through its application to two well-known simplified models of atmospheric physics: damped oscillations and Lorenz’s three-component model of dry cellular convection. The major findings of this study include the following: (i) Use of a nonmonotonic forward model in the inverse problem gives rise to the potential for a multimodal posterior PDF, the realization of which depends on the information content of the observations and on observation and model uncertainties. (ii) The cumulative effect of observations over time, space, or both could render the final posterior PDF unimodal, even with the nonmonotonic forward model. (iii) A greater number of independent observations are needed to constrain the solution in the case of a nonmonotonic nonlinear model than for a monotonic nonlinear or linear forward model for a given number of degrees of freedom in control parameter space. (iv) A nonlinear monotonic forward model gives rise to a skewed unimodal posterior PDF, implying a well-posed maximum likelihood inverse problem. (v) The presence of model error greatly increases the possibility of capturing multiple modes in the posterior PDF with the nonmonotonic nonlinear model. (vi) In the case of a nonlinear forward model, use of a Gaussian approximation for the prior update has a similar effect to an increase in model error, which indicates there is the potential to produce a biased mean central estimate even when observations and model are unbiased.

scholarly journals PEMETAAN STRUKTUR SITUS COT SIDI ABDULLAH PENINGGALAN KERAJAAN SAMUDERA PASAI BERDASARKAN SEBARAN MODEL RESISTIVITAS

2020 ◽  
Vol 12 (02) ◽  
pp. 115
Author(s):  
Agus Hari Pramana ◽  
Faisal Abdullah ◽  
Tomi Afrizal ◽  
Nazli Ismail
Keyword(s):  
Sea Water ◽  
Middle Part ◽  
Electrode Spacing ◽  
Dc Resistivity ◽  
Brick Wall ◽  
Model Resolution ◽  
Resistivity Method ◽  
Wall Structures ◽  
Method Model ◽  
Sand Material

Metode DC-Resistivity konfigurasi Wenner telah diaplikasikan pada situs cagar budaya Cot Sidi Abdullah (CSA) di Desa Kuta Krueng, Kecamatan Samudra Pasai, Kabupaten Aceh Utara. Data geolistrik diukur pada 8 lintasan sejajar dengan spasi lintasan 5 meter dari arah utara - selatan sepanjang situs dan spasi elektroda 0,5 meter. Berdasarkan hasil model penampang 2D diperoleh zona yang bersifat konduktif dengan kisaran nilai resistivitas 0,1 – 80 Ωm dan zona resistif dengan nilai reistivitas berkisar antara 100 – 600 Ωm dengan ketebalan lapisan 1 meter. Keberadaan zona yang relatif konduktif disebabkan oleh adanya intrusi air asin yang terdapat disekeliling daerah itu, yaitu area tambak dan sungai. Sedangkan zona resistif terdapat secara merata di semua lintasan yang umumnya berada di tengah–tengah lintasan dan dapat diprediksikan sebagai bagian dari situs yang tertimbun dibawah permukaan. Zona resistif berupa batu bata yang berada di sekeliling situs dan menahan intrusi air asin masuk ke tengah. Oleh karena itu bangunan Situs CSA diprediksi memiliki luasan sekitar 26 m x 35 m dengan bangunan sekeliling berupa batu bata dengan ketebalan dinding situs 1,5 meter. Sedangkan bagian tengah adalah timbunan pasir yang tidak dipengaruhi oleh air asin.Kata kunci: Metode geofisika, Arkeologi, Cot Sidi Abdullah, Metode DC - Resistivity, Resolusi Model, RekontruksiThe DC-Resistivity method with Wenner configurations was applied to the cultural heritages of Cot Sidi Abdullah (CSA) in Kuta Krueng Village, Samudra Pasai District, North Aceh Regency. Resistivity data were measured on 8 parallel lines with 5 meterline spacing from north to south of the sites and 0.5 meter electrode spacing. The 2D model results show that there are conductive region with the value of resistivity from 0.1-80 Ωm and resistive region with resistivity values ranging from 100 - 600 with a thickness of 1 meter. The existence of the relatively conductive region is caused by the sea water intrusions which is found surrounding the area, such as fish and river areas. However the resistive region is evenly found in all of the lines which are generally located in the middle of line and it was predicted as a part of Cot Sidi Abdullah site buried under the surface. The resistive region is consist of brick wall structures which surrounding the site can hold the sea water intrusions into the center of the sites. Therefore it can be concluded that the CSA Site has 26 m x 35 m areas which is surrounded by the brick structures with 1.5 meters thick. Howeverthe middle part of the site is filled with a sand material that is not affected by salt water.Key words: Geophysics Method, Archaeology, Cot Sidi Abdullah, DC- Resistivity Method, Model Resolution, Reconstruction

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