INCREASING THE COST-EFFECTIVENESS OF IN VITRO RESEARCH THROUGH THE USE OF TITANIUM IN THE DEVICE FOR MEASURING THE ELECTRICAL PARAMETERS OF CELLS

Currently, various methods are used to assess the biocompatibility of materials. After an in-depth and detailed review of the literature, the method used in the research was selected. As part of the experiments, a method based on the analysis of the values ​​of electrical parameters of cell cultures measured in the presence of electrodes was used. The electrode is a structure made of a thin layer of metallization. It measures the change in resistance, impedance and capacity of a mixture of cells and the substance in which they are grown. The plate containing the electrode assembly is called the measurement matrix. Currently, commercially used test matrices are made of gold or platinum. However, their high price means that large-scale research is significantly limited. In order to increase the access to the widespread use of this method, it was decided that it was necessary to use cheaper materials, reducing the necessary costs of conducting experiments. Considering this, an attempt was made to use a different conductive material to build matrices compatible with the ECIS® Z-Theta measurement system. Their use would enable in vitro research on living cells. In the presented work, titanium was used as a material that may turn out to be an alternative to the materials currently used. Its application to the production of matrices will allow to study the influence of this metal on the behavior of cells.

Generation of test matrices with specified eigenvalues using floating-point arithmetic

This paper concerns test matrices for numerical linear algebra using an error-free transformation of floating-point arithmetic. For specified eigenvalues given by a user, we propose methods of generating a matrix whose eigenvalues are exactly known based on, for example, Schur or Jordan normal form and a block diagonal form. It is also possible to produce a real matrix with specified complex eigenvalues. Such test matrices with exactly known eigenvalues are useful for numerical algorithms in checking the accuracy of computed results. In particular, exact errors of eigenvalues can be monitored. To generate test matrices, we first propose an error-free transformation for the product of three matrices YSX. We approximate S by ${S^{\prime }}$ S ′ to compute ${YS^{\prime }X}$ Y S ′ X without a rounding error. Next, the error-free transformation is applied to the generation of test matrices with exactly known eigenvalues. Note that the exactly known eigenvalues of the constructed matrix may differ from the anticipated given eigenvalues. Finally, numerical examples are introduced in checking the accuracy of numerical computations for symmetric and unsymmetric eigenvalue problems.

Statistical Assessment of Parameters Affecting Firebrand Pile Heat Transfer to Surfaces

Firebrands are known to cause ignition of structures far from the primary fire front, resulting in significant damage to structures before firefighting can be attempted. To make structures more resilient to firebrand ignition, a better understanding of the heat transfer from firebrands to surfaces is needed. This paper provides a statistical assessment of different factors expected to have an impact on the heat flux from firebrand piles to a flat surface. The factors included in the study were wood moisture content, wood type (hardwood or softwood), wood density, wood state (live, dead, or artificial), wind speed, pile mass, firebrand diameter, and firebrand length. Using design of experiments, test matrices were developed that permitted a statistical analysis to be performed on the data. This statistical analysis was used to quantify which factors had a statistically significant impact on the heat flux from the pile as well as ranking the importance of the different factors. Artificial firebrands were found to have statistically higher heat fluxes compared with natural firebrands. Other factors that had a statistically significant impact on the heat flux were wind speed, firebrand length, and firebrand length-diameter interaction. Firebrand aspect ratio (related to the firebrand length-diameter interaction) is directly related to the pile porosity, which is a measure of the volume of air in the pile. Increasing the aspect ratio (which increases the pile porosity) results in higher heat fluxes across a larger region of the pile and was found to be an important factor. Firebrand diameter and pile mass were found to affect the burning duration but not as significantly as other parameters. The number of firebrands in the pile was also observed to potentially affect the heat flux, with a critical number required to reach the highest heat flux for a given firebrand geometry.

The effect of dietary fibers on the viscoelastic properties of the gluten-free cookie dough

The significance of inclusion of associated dietary fibres in various amounts to the formulations of gluten-free rice test mixtures based on rheological profile of hydrated fibrous-flour composite mixtures was investigated. To assess the viscoelasticity of fiber-enriched rice-based test matrices, dual fundamental (dynamic oscillatory and creep recovery tests) and empirical (consistency and viscometric profile) rheological approaches were adopted. The obtained functional variables were analyzed for the dependence on the hydration of the dough and dietary fibres, as well as for the correlations within the parameters of both small and large deformation tests. The aqueous competition of fiber macromolecules, exhibiting different water binding and gelling capacities, led to additive, synergistic and/or antagonistic effects on the basic rheological properties.

Review on ducted fans for compound rotorcraft

ABSTRACTThis paper presents a survey of published works on ducted fans for aeronautical applications. Early and recent experiments on full- or model-scale ducted fans are reviewed. Theoretical studies, lower-order simulations and high-fidelity CFD simulations are also summarised. Test matrices of several experimental and numerical studies are compiled and discussed. The paper closes with a summary of challenges for future ducted fan research.

An implicit algorithm for computing the minimal Gersgorin set

In this paper we present a new algorithm for the computation of the minimal Gersgorin set that can be considered an extension of the results from [5]. While the general approach to calculation of the boundary of the minimal Gersgorin set is kept, the core numerical calculation is changed. Namely, the problem is formulated in such a way that the eigenvalue computations are replaced by LU decompositions, allowing the algorithm to be used for larger matrices more efficiently. To illustrate the benefits, we compare both algorithms on several test matrices.

Enlarged GMRES for solving linear systems with one or multiple right-hand sides

We propose a variant of the generalized minimal residual (GMRES) method for solving linear systems of equations with one or multiple right-hand sides. Our method is based on the idea of the enlarged Krylov subspace to reduce communication. It can be interpreted as a block GMRES method. Hence, we are interested in detecting inexact breakdowns. We introduce a strategy to perform the test of detection. Furthermore, we propose a technique for deflating eigenvalues that has two benefits. The first advantage is to avoid the plateau of convergence after the end of a cycle in the restarted version. The second is to have very fast convergence when solving the same system with different right-hand sides, each given at a different time (useful in the context of a constrained pressure residual preconditioner). We test our method with these deflation techniques on academic test matrices arising from solving linear elasticity and convection–diffusion problems as well as matrices arising from two real-life applications, seismic imaging and simulations of reservoirs. With the same memory cost we obtain a saving of up to $50 \%$ in the number of iterations required to reach convergence with respect to the original method.