Conforming and nonconforming finite element methods for biharmonic inverse source problem

This paper deals with the numerical approximation of the biharmonic inverse source problem in an abstract setting in which the measurement data is finite-dimensional. This unified framework in particular covers the conforming and nonconforming finite element methods (FEMs). The inverse problem is analysed through the forward problem. Error estimate for the forward solution is derived in an abstract set-up that applies to conforming and Morley nonconforming FEMs. Since the inverse problem is ill-posed, Tikhonov regularisation is considered to obtain a stable approximate solution. Error estimate is established for the regularised solution for different regularisation schemes. Numerical results that confirm the theoretical results are also presented.

Cortical Source Analysis of Event-Related Potentials: A Developmental Approach

Cortical source analysis of electroencephalographic (EEG) signals has become an important tool in the analysis of brain activity. The aim of source analysis is to reconstruct the cortical generators (sources) of the EEG signal recorded on the scalp. The quality of the source reconstruction relies on the accuracy of the forward problem, and consequently the inverse problem. An accurate forward solution is obtained when an appropriate imaging modality (i.e., structural magnetic resonance imaging – MRI) is used to describe the head geometry, precise electrode locations are identified with 3D maps of the sensor positions on the scalp, and realistic conductivity values are determined for each tissue type of the head model. Together these parameters contribute to the definition of realistic head models. Here, we describe the steps necessary to reconstruct the cortical generators of the EEG signal recorded on the scalp. We provide an example of source reconstruction of event-related potentials (ERPs) during a face-processing task performed by a 6-month-old infant. We discuss the adjustments necessary to perform source analysis with measures different from the ERPs. The proposed pipeline can be applied to the investigation of different cognitive tasks in both younger and older participants.

Efficient production of human neutrophils from iPSCs that prevent murine lethal infection with immune cell recruitment

Neutrophils play an essential role in innate immune responses to bacterial and fungal infections and loss of neutrophil function can increase the risk of acquiring lethal infections in clinical settings. Here, we show that engineered neutrophil-primed progenitors derived from human induced pluripotent stem cells (iPSCs) can produce functional neutrophil-like cells at a clinically applicable scale that can act rapidly in vivo against lethal bacterial infections. Using five different mouse models, we systematically demonstrated that these neutrophil-like cells migrate to sites of inflammation and infection and increase survival against bacterial infection. In addition, we found that these human neutrophil-like cells can recruit murine immune cells. This system potentially provides a straight-forward solution for patients with neutrophil deficiency-an off-the-shelf neutrophil transfusion. This platform should facilitate the administration of human neutrophils for a broad spectrum of physiological and pathological conditions.

Stochastic Particle Tracking Application in Different Urban Areas in Central Europe: The Milano (IT) and Jaworzno (PL) Case Study to Secure the Drinking Water Resources

Urban areas are typically characterized by the presence of industrial sites, which are often sources of groundwater contamination, posing a serious threat for the groundwater. In such cases, a crucial step is to find a link between the contaminant sources and freshwater supply wells at risk. As a part of the AMIIGA Project, two different stochastic approaches were applied to assess drinking water supply wells vulnerability in Functional Urban Areas in the presence of several chlorinated hydrocarbons sources in an alluvial aquifer in Milano and a pesticide mega site in a complex geological setting in Poland. In the first case study, the innovative Pilot Point Null-Space Monte Carlo forward particle tracking was used, applying a forward solution instead of the classical backtracking, while in the second case was chosen the classical Monte Carlo methodology. Both case studies represent useful application examples, allowing an effective prioritization of expensive remediation actions in order to protect freshwater wells.

A Comparison Study of Explicit and Implicit 3-D Transient Electromagnetic Forward Modeling Schemes on Multi-Resolution Grid

This study compares the efficiency of 3-D transient electromagnetic forward modeling schemes on the multi-resolution grid for various modeling scenarios. We developed time-domain finite-difference modeling based on the explicit scheme earlier. In this work, we additionally implement 3-D transient electromagnetic forward modeling using the backward Euler implicit scheme. The iterative solver is used for solving the system of equations and requires a proper initial guess that has significant effect on the convergence. The standard approach usually employs the solution of a previous time step as an initial guess, which might be too conservative. Instead, we test various initial guesses based on the linear extrapolation or linear combination of the solutions from several previous steps. We build up the implicit scheme forward modeling on the multi-resolution grid, which allows for the adjustment of the horizontal resolution with depth, hence improving the performance of the forward operator. Synthetic examples show the implicit scheme forward modeling using the linearly combined initial guess estimate on the multi-resolution grid additionally reduces the run time compared to the standard initial guess approach. The result of comparison between the implicit scheme developed here with the previously developed explicit scheme shows that the explicit scheme modeling is more efficient for more conductive background models often found in environmental studies. However, the implicit scheme modeling is more suitable for the simulation with highly resistive background models, usually occurring in mineral exploration scenarios. Thus, the inverse problem can be solved using more efficient forward solution depending on the modeling setup and background resistivity.

The Horizontal Loop Electromagnetic (HLEM) Response of Ifewara Transcurrent Fault,Southwestern Nigeria: A Computational Results

The need to accurately interpret geological models that approximate mineralized zones in a Basement Complex terrain necessitate the development of horizon loop electromagnetic method (HLEM) forward modeling solutions for such scenarios. The focus of the present work is on finding rapid forward modeling solutions for synthetic HLEM data as an aid in exploration for moderate to deep conductive mineral exploration targets.The main thrust is obtaining idealized HLEM models that are required for geological interpretation of the subsurface in such environment. The original HLEM equations developed by Wesley were extended to represent a horizontally stratified earth with a conductive approximated by shear zone. From these equations a computer program was written to calculate the HLEM responses for optimal conductor model with known values of coil separations (L), depth of burial (z) and angle of dip of the target.The thin conductive model was used because it is simple and suitable for different geological scenarios. The accuracy of the approximate forward solution has been confirmed for HLEM systems with various geometric ranges, frequencies and conductivities. Three models having varying overburden thickness, dip angle of target and source-receiver separation were used in the forward modeling. The effect of varying the dip angle,overburden thickness and coil separation was studied in all the three models used. The result obtained from the forward modeling showed that variation of the dip angle gave rise to changes in the amplitudes of the anomalies generated, while that of overburden and coil separation gave rise to changes in anomaly shape. Also, the geometry and position of the causative body were precisely delineated.

Estimation of Heat Flux in Two-Dimensional Nonhomogeneous Parabolic Equation Based on a Sufficient Descent Levenberg–Marquard Algorithm

The main work of this paper focuses on identifying the heat flux in inverse problem of two-dimensional nonhomogeneous parabolic equation, which has wide application in the industrial field such as steel-making and continuous casting. Firstly, the existence of the weak solution of the inverse problem is discussed. With the help of forward solution and dual equation, this paper proves the Lipchitz continuity of the cost function and derives the Lipchitz constant. Furthermore, in order to accelerate the convergence rate and reduce the running time, this paper presents a sufficient descent Levenberg–Marquard algorithm with adaptive parameter (SD-LMAP) to solve this inverse problem. At last, compared with other methods, the results of simulation experiment show that this algorithm can obviously reduce the running time and iterative number.

ENHANCING THE PERFORMANCE OF FISSION SOURCE CONVERGENCE WITH FUNCTIONAL EXPANSION TALLIES IN SERPENT 2 MONTE CARLO CODE

This paper presents an upgrade to the built-in response matrix based solver implemented in Serpent 2 Monte Carlo code aiming to improve the fission source convergence when obtaining the forward solution to the k-eigenvalue criticality source problems. The functional expansion tallies are introduced in an attempt to improve the accuracy of the cell-wise form factors that feed the response matrix solver, replacing the current mesh-based approach. The functional expansion tallies reconstruct the binning surface and collision tallies, by using high-order series expansion to represent the original and continuous spatial distributions. This new feature is implemented to Serpent 2 and tested by single-assembly and full-core PWR calculations (BEAVRS benchmark). The results show enhanced performance of the convergence acceleration methodology based on an improved initial guess of the fission source.

The Problems Faced with E-Procurement Management in Chipre and Turkey

The rapid development in communication technologies, is creating new possibilities in our commercial life. In particular, the development and expansion of the use of the internet has resulted in businesses conducting their commercial activities in an electronic environment. The new business concept, which we define as e-business, offers a wide range of market opportunities to both businesses and customers. In our article, it is aimed to establish a starting point for similar studies in the commercial relations with Turkey, which is the country with which 62% of imports and 57.2% of exports according to the end of 2018 data of the Trade Department of Northern Cyprus, by putting forward solution proposals in order to determine the similarities and differences in e-business managers Moreover, Turkey, which is among the 20 largest countries in the world economically, and Northern Cyprus, one of the world's smallest economies, may also have an effect on the problems faced with E-provision, whether economic size makes a difference or not. The survey was prepared for the senior managers of the businesses to which it was applied. The results of our survey showed that the managers in the two countries had similar thoughts about the problems of e-provisioning, and that the economic magnitude did not differ greatly on the problems of e-provisioning studies conducted in electronic environment.