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Search results for: BAFFLE FACTOR
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The Design of Cavity Resonators and Microwave Filters Applying Shape Deformation Techniques
PublicationThis article introduces shape deformation as a new approach to the computer-aided design (CAD) of high-frequency components. We show that geometry deformation opens up new design possibilities and offers additional degrees of freedom in the 3-D modeling of microwave structures. Such design flexibility is highly desirable if the full potential of additive manufacturing (AM) is to be exploited in the fabrication of RF and microwave...
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The lanthanide influence on selected properties of BaLnCo2O6-δ
PublicationThe subject of research of this dissertation are cobalt oxides with a double perovskite structure with a general formula BaLnCo2O6-δ, where Ln stands for La, Pr, Nd, Sm, Gd, Tb, Dy. The aim of the study was to verify the ability of these materials to form the protonic defects, as well as to identify the factors determining this ability. As part of the work, materials from the proposed group were synthesised and characterized. To...
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Application of chemometric modeling for ionic liquid-based ultrasonic-assisted dispersive liquid-liquid microextraction: Analysis of fosetyl-aluminum in fruit and vegetable samples
PublicationThis manuscript presents a new method for selective extraction and determination of fosetyl-aluminum in fruits and vegetable samples based on ultrasonic-assisted dispersive liquid-liquid microextraction method using ionic liquids (IL-UA-DLLME). A UV-Visible spectrophotometer was used for detection and quantification. Plants used for sample collection were grown under controlled conditions in a greenhouse. Central composite design...
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Vertical Temperature Stratification of the Gulf of Gdansk Water
PublicationThe Baltic Sea is characterized by variable hydroacoustic conditions, which depend on hydrological conditions throughout the year. The temperature of the water is the factor that has the greatest impact on the changes in the speed of the sound in this basin. Even at a small depth, we can observe a large temperature gradient affecting the accuracy of the conducted research using hydroacoustic devices. A characteristic feature of...
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Organizational IT Competency, Knowledge Workers and Knowledge Sharing
PublicationIT competency plays a vital role in knowledge management processes. Information technology affects an organization’s ability to store and recall knowledge that has been made explicit through codification, including different forms such as written documents, reports, presentations, patents, formulas, etc. This study aims to measure the influence of a company’s IT competency dimensions such as IT-knowledge,...
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Ion conduction in beryllium-alumino-silicate glasses doped with sodium or sodium and lithium ions
PublicationElectrical properties of beryllium-alumino-silicate glasses containing sodium ions or sodium and lithium ions were studied with impedance spectroscopy technique over a frequency range from 10 mHz to 1 MHz and at temperature range from 213 to 473 K. The frequency- and temperature-dependent conductivity spectra of individual single alkali glasses were superimposed by means of the Summerfield scaling. Mixed-alkali glasses do not overlap...
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Surface finite viscoelasticity and surface anti-plane waves
PublicationWe introduce the surface viscoelasticity under finite deformations. The theory is straightforward generalization of the Gurtin–Murdoch model to materials with fading memory. Surface viscoelasticity may reflect some surface related creep/stress relaxation phenomena observed at small scales. Discussed model could also describe thin inelastic coatings or thin interfacial layers. The constitutive equations for surface stresses are...
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On well-posedness of the first boundary-value problem within linear isotropic Toupin–Mindlin strain gradient elasticity and constraints for elastic moduli
PublicationWithin the linear Toupin–Mindlin strain gradient elasticity we discuss the well-posedness of the first boundary-value problem, that is, a boundary-value problem with Dirichlet-type boundary conditions on the whole boundary. For an isotropic material we formulate the necessary and sufficient conditions which guarantee existence and uniqueness of a weak solution. These conditions include strong ellipticity written in terms of higher-order...
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Strong ellipticity conditions and infinitesimal stability within nonlinear strain gradient elasticity
PublicationWe discuss connections between the strong ellipticity condition and the infinitesimal instability within the nonlinear strain gradient elasticity. The strong ellipticity (SE) condition describes the property of equations of statics whereas the infinitesimal stability is introduced as the positive definiteness of the second variation of an energy functional. Here we establish few implications which simplify the further analysis...
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Ellipticity of gradient poroelasticity
PublicationWe discuss the ellipticity properties of an enhanced model of poroelastic continua called dilatational strain gradient elasticity. Within the theory there exists a deformation energy density given as a function of strains and gradient of dilatation. We show that the equilibrium equations are elliptic in the sense of Douglis–Nirenberg. These conditions are more general than the ordinary and strong ellipticity but keep almost all...
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On the material symmetry group for micromorphic media with applications to granular materials
PublicationWithin the framework of the theory of nonlinear elastic micromorphic continua we introduce the new definition of the local material symmetry group. The group consists of ordered triples of second- and third-order tensors describing such changes of a reference placement that cannot be recognized with any experiment. Using the definition we characterize the micromorphic isotropic media, micromorphic fluids, solids and special intermediate...
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On the peculiarities of anti-plane surface waves propagation for media with microstructured coating
PublicationWe discuss new type of surface waves which exist in elastic media with surface energy. Here we present the model of a coating made of polymeric brush. From the physical point of view the considered model of surface elasticity describes a highly anisotropic surface coating. Here the surface energy model could be treated as 2D reduced strain gradient continuum as surface strain energy depends on few second spatial derivatives of...
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Linear Micropolar Elasticity Analysis of Stresses in Bones Under Static Loads
PublicationWe discuss the finite element modeling of porous materials such as bones using the linear micropolar elasticity. In order to solve static boundary-value problems, we developed new finite elements, which capture the micropolar behavior of the material. Developed elements were implemented in the commercial software ABAQUS. The modeling of a femur bone with and without implant under various stages of healing is discussed in details
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On Non-holonomic Boundary Conditions within the Nonlinear Cosserat Continuum
PublicationWithin the framework of the nonlinear micropolar elastic continuum we discuss non-holonomic kinematic boundary conditions. By non-holonomic boundary conditions we mean linear relations between virtual displacements and virtual rotations given on the boundary. Such boundary conditions can be used for modelling of complex material interactions in the vicinity of the boundaries and interfaces.
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On Dynamic Boundary Conditions Within the Linear Steigmann-Ogden Model of Surface Elasticity and Strain Gradient Elasticity
PublicationWithin the strain gradient elasticity we discuss the dynamic boundary conditions taking into account surface stresses described by the Steigmann–Ogden model. The variational approach is applied with the use of the least action functional. The functional is represented as a sum of surface and volume integrals. The surface strain and kinetic energy densities are introduced. The Toupin–Mindlin formulation of the strain gradient elasticity...
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On Anti-Plane Surface Waves Considering Highly Anisotropic Surface Elasticity Constitutive Relations
PublicationWithin the framework of highly anisotropic surface elasticity model we discuss the propagation of new type of surface waves that are anti-plane surface waves. By the highly anisotropic surface elasticity model we mean the model with a surface strain energy density which depends on incomplete set of second derivatives of displacements. From the physical point of view this model corresponds to a coating made of a family of parallel...
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A Nonlinear Model of a Mesh Shell
PublicationFor a certain class of elastic lattice shells experiencing finite deformations, a continual model using the equations of the so-called six-parameter shell theory has been proposed. Within this model, the kinematics of the shell is described using six kinematically independent scalar degrees of freedom — the field of displacements and turns, as in the case of the Cosserat continuum, which gives reason to call the model under consideration...
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Two- and three-dimensional elastic networks with rigid junctions: modeling within the theory of micropolar shells and solids
PublicationFor two- and three-dimensional elastic structures made of families of flexible elastic fibers undergoing finite deformations, we propose homogenized models within the micropolar elasticity. Here we restrict ourselves to networks with rigid connections between fibers. In other words, we assume that the fibers keep their orthogonality during deformation. Starting from a fiber as the basic structured element modeled by the Cosserat...
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Strongly anisotropic surface elasticity and antiplane surface waves
PublicationWithin the new model of surface elasticity, the propagation of anti-plane surface waves is discussed. For the proposed model, the surface strain energy depends on surface stretching and on changing of curvature along a preferred direction. From the continuum mechanics point of view, the model describes finite deformations of an elastic solid with an elastic membrane attached on its boundary reinforced by a family of aligned elastic...
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Minimal surfaces and conservation laws for bidimensional structures
PublicationWe discuss conservation laws for thin structures which could be modeled as a material minimal surface, i.e., a surface with zero mean curvatures. The models of an elastic membrane and micropolar (six-parameter) shell undergoing finite deformations are considered. We show that for a minimal surface, it is possible to formulate a conservation law similar to three-dimensional non-linear elasticity. It brings us a path-independent...
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Local material symmetry group for first- and second-order strain gradient fluids
PublicationUsing an unified approach based on the local material symmetry group introduced for general first- and second-order strain gradient elastic media, we analyze the constitutive equations of strain gradient fluids. For the strain gradient medium there exists a strain energy density dependent on first- and higher-order gradients of placement vector, whereas for fluids a strain energy depends on a current mass density and its gradients....
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Fiscal decentralization in the European Countries: a cluster analysis approach
PublicationThe scope of public authority depend on many factors. One of them is a declaration, usually expressed in the constitution of a given country (Sferlea, 2014, Libman, 2010, Nehmelman, Vetzo, 2016) of the application of the decentralisation principle in the performance of public tasks. Despite this declaration, the structure of the public sector and the tasks carried out at different levels in particular countries are not identical....
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Proposition of the methodology for Data Acquisition, Analysis and Visualization in support of Industry 4.0
PublicationIndustry 4.0 offers a comprehensive, interlinked, and holistic approach to manufacturing. It connects physical with digital and allows for better collaboration and access across departments, partners, vendors, product, and people. Consequently, it involves complex designing of highly specialized state of the art technologies. Thus, companies face formidable challenges in the adoption of these new technologies....
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Optimization-Based High-Frequency Circuit Miniaturization through Implicit and Explicit Constraint Handling: Recent Advances
PublicationMiniaturization trends in high-frequency electronics have led to accommodation challenges in the integration of the corresponding components. Size reduction thereof has become a practical necessity. At the same time, the increasing performance demands imposed on electronic systems remain in conflict with component miniaturization. On the practical side, the challenges related to handling design constraints are aggravated by the...
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GVC and wage dispersion. Firm-level evidence from employee-employer database
PublicationResearch background: Wage inequalities are still part of an interesting policy-oriented research area. Given the developments in international trade models (heterogeneity of firms) and increasing availability of micro-level data, more and more attention is paid to wage differences observed within and be-tween firms. Purpose of the article: The aim of the paper is to address the research gap concerning limited cross-country evidence...
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Various approaches to a human preference analysis in a digital signage display design
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Low-energy positron scattering from gas-phase benzene
PublicationIn this paper we are presenting calculations of the elastic cross section of positrons with gas-phase benzene for the energy range from 0.25 eV to 9.0 eV. The calculations are done with the molecular R-matrix method for positron-scattering from poly-atomic molecules using a scaling factor to scale the electron-positron interaction. The scaling factor influences the position of the poles of the R-matrix. We adjust the scaling factor...
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Wpływ równości nawierzchni i dynamicznego oddziaływania pojazdów ciężkich na trwałość zmęczeniową nawierzchni podatnych
PublicationPodczas ruchu pojazdu obserwuje się odchylenia nacisków osi pojazdów od nacisku statycznego, co jest spowodowane nierównościami nawierzchni. Dynamiczne obciążenia pojazdów w większym stopniu wytężają konstrukcję nawierzchni drogowej. Rozkład obciążeń dynamicznych ma kształt rozkładu normalnego i jest opisywany poprzez obciążenie statyczne oraz wskaźniki dynamiczne DI lub DLC. Wraz z pogorszeniem równości i zwiększeniem prędkości...
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The Polish adaptation of the Burnout Assessment Tool (BAT-PL) by W. Schaufeli et al.
PublicationAim. The study aimed to present the Polish version of the Burnout Assessment Tool (BAT-PL) by Schaufeli et al. and to assess its validity and reliability. The tool measures the core symptoms of burnout (BAT-C): exhaustion, mental distance, cognitive and emotional impairment, and its secondary symptoms (BAT-S): psychosomatic complaints and psychological distress. Method. The participants were 255 nursing staff members. The construct...
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Upgrading low value-added activities in global value chains: a functional specialisation approach
PublicationThis paper aims to identify patterns of functional specialisation (FS) in global value chains (GVCs) and determinants of upgrading them for selected Central Eastern European (CEE) economies. By combing the World Input-Output Database with data on occupations, we reveal a new FS pattern among subgroups of CEEs. Poland and Slovakia have an unfavourable GVC position and specialise in low value-added fabrication function. In contrast,...
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Investigation of use of hydrophilic/hydrophobic NADESs for selective extraction of As(III) and Sb(III) ions in vegetable samples: Air assisted liquid phase microextraction and chemometric optimization
PublicationIn this paper, a green, cost-effective sample preparation method based on air assisted liquid phase microextraction (AA-LPME) was developed for the simultaneous extraction of As(III) and Sb(III) ions from vegetable samples using hydrophilic/hydrophobic natural deep eutectic solvents (NADESs). Central composite design was used for the optimization of extraction factors including NADES volume, extraction cycle, pH, and curcumin concentration....
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Psychometric properties of the Bern illegitimate tasks scale using classical test and item response theories
PublicationCombining a classical test theory and an item response theory (IRT), this study aimed to investigate the psychometric properties of the Bern Illegitimate Tasks Scale (BITS) by measuring two conceptually separate dimensions capturing unnecessary tasks (perceived by employees as pointless) and unreasonable tasks (perceived as unfairly or inappropriately assigned). Data collected among Polish employees in two samples (N= 965 and N=...
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Thermal and technological aspects of double face grinding of C45 carbon steel
PublicationIn grinding, the contact zone temperature is a decisive factor influencing the achievable surface quality and the grinding tool wear. In contrast to other grinding processes, only few information regarding double face grinding with planetary kinematics when processing steel is known up to date. Since the successive substitution of in-dustrial double-sided lapping processes by double-sided grinding, it has become necessary to the...
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Compulsive sexual behavior and dysregulation of emotion
PublicationIntroduction Dysregulation of emotion (DE) is commonly seen in individuals suffering from compulsive sexual behavior (CSB), as well as represents a crucial element of its common comorbidities like mood, anxiety, and substance use disorders. Aim To investigate the links between CSB and DE. Methods A review of pertinent literature on CSB and DE was performed using EBSCO, PubMed, and Google Scholar databases. Main Outcome Measure...
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Classification of high-voltage varistors into groups of differentiated quality
PublicationThe research was aimed on defining a factor of quality for high-voltage varistors using Non-Destructive Testing (NDT) techniques, which could be applied during the production testing. The newly proposed parameter Q determined on the basis of the lowest resonant frequency fr measured within the preselected frequency range was taken into account. The parameter Q was defined for ZnO structures after firing, without metallized contacts....
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Should Polish banks be domesticated?
PublicationThe financial crisis revealed vulnerabilities in the regulation and supervision of the banking system. The overarching goal of the proposal (Bazylea III and CRD IV) is to strengthen the resilience of the EU banking sector. The effects of these regulations will be detrimental to the Polish banking system and economy. This follows from the fact that listed banks in Poland are subsidiaries of international banking groups. The article...
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Succinite, Baltic Amber: A Chemical Masterpiece of Nature
PublicationSuccinite, Baltic amber, is one of the most appreciated fossil resins. Its beauty has fascinated people since prehistoric times. It is a substance, and also gemstone, whose uniqueness is due to its compelling, though still not fully understood, physicochemical nature. In this article, some facts about the physical and chemical properties of succinite in order to find an answer for questions about the unique properties of this resin,...
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Evolving neural network as a decision support system — Controller for a game of “2048” case study
PublicationThe paper proposes an approach to designing the neuro-genetic self-learning decision support system. The system is based on neural networks being adaptively learned by evolutionary mechanism, forming an evolved neural network. Presented learning algorithm enables for a selection of the neural network structure by establishing or removing of connections between the neurons, and then for a finding the beast suited values of the network...
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Polarisation effects in low-energy positron–molecule scattering
PublicationThe UK molecular R-matrix method has been adapted to treat positron collisions from polyatomic targets. A simple empirical enhancement factor which corrects for the underestimation of electron–positron polarisation and correlation effects in the calculations performed with the static-plus-polarization model at low scattering energies is presented. Application of this model to positron scattering from carbon dioxide at energies...
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Islamskie finanse i bankowość: czynniki rozwoju oraz typowe ryzyka.
PublicationCelem artykułu jest przybliżenie oraz wyjaśnienie podłoża rozwoju i ekspansji islamskich finansów i bankowości. Artykuł można podzielić na dwie główne części. W pierwszej (w 2. rozdziale) dokonano wyjaśnienia źródeł pochodzenia finansów islamskich; a także wskazano czynniki mające wpływ na powstanie pierwszych zorganizowanych struktur oraz dalszą ekspansję finansów i bankowości islamskiej. Następnie w drugiej części artykułu (w...
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Dimensioning of vortex storm overflows
PublicationVortex flow control can be made as a rotational chamber, where the centrifugal force is a supporting factor. The paper presents a simplified, but experimentally verified, method of such device designing.
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CONDITIONS OF THE GREEN TRANSFORMATION. THE CASE OF THE EUROPEAN UNION
PublicationThe main purpose of the paper is to identify the factors that determine the course of green transformation and to assess the current stage and possible directions of change in subsequent years in EU countries. The literature lacks comprehensive studies that show the impact of diverse types of factors on the course of green transformation. For this purpose, two perspectives of the research – economic and environmental – are usually...
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Customer Assessment of Brand Valuation and Social Media
PublicationThe research problem engaged in this article is to determine whether contemporary consumers are able to assess brand equity in the overabundance of brands and products with similar features and qualities. The author argues that in the existing circumstances when differences between brands become insignificant the consumer is not capable of assessing their equity adequately. In order to verify the thesis the author has accepted...
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Impact of selected parameters of the fermentation process of wine and wine itself on the biogenic amines content: Evaluation by application of chemometric tools
PublicationThe demand for safer foods has promoted more research into biogenic amines (BAs) over the past few years, however, there are still some questions that remain unanswered. Despite the fact that BAs are present in wine and can cause toxic effect to the body, a shared regulation limiting the amounts of BAs in wine is still lacking. A detailed understanding of their presence in wine is also important for the food trade sector. Therefore,...
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Branża IT – wyzwania związane z zarządzaniem kapitałem ludzkim
PublicationArtykuł dotyczy procesów zarządzania kapitałem ludzkim w firmach IT, w których największe wyzwania wiążą się z dwoma obszarami: zatrudniania i zatrzymywania specjalistów IT w organizacji. Działy HR prześcigają się w stosowaniu coraz to nowszych rozwiązań, aby pozyskać oraz motywować kompetentnych informatyków do pracy na rzecz firmy. Głównym celem artykułu jest prezentacja działań dotyczących rekrutacji oraz motywowania pracowników...
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An evaluation and explanation of (in)efficiency in higher education institutions in Europe and the U.S. with the application of two-stage semi-parametric DEA
PublicationThis study uses data envelopment analysis (DEA) to evaluate the relative efficiency of 500 higher education institutions (HEIs) in ten European countries and the U.S. for the period between 2000 and 2010. Efficiency scores are determined using different input-output sets (inputs: total revenue, academic staff, administration staff, total number of students; outputs: total number of publications, number of scientific articles, graduates)...
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Urban flash flood hazard identification and assessment applying geospatial techniques and hydrodynamic modeling; Erbil city case study, Kurdistan Region of Iraq
PublicationThis dissertation aims to investigate the factors behind flash flooding in Erbil's central district, located in the Kurdistan Region of Iraq, and develop a methodology for assessing flood hazards in the city, despite limited data accessibility. In this thesis, each factor was investigated, including analyzing extreme precipitation events in the last two decades, including their spatial and temporal distribution of rainfall, intensity,...
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Separability Assessment of Selected Types of Vehicle-Associated Noise
PublicationMusic Information Retrieval (MIR) area as well as development of speech and environmental information recognition techniques brought various tools in-tended for recognizing low-level features of acoustic signals based on a set of calculated parameters. In this study, the MIRtoolbox MATLAB tool, designed for music parameter extraction, is used to obtain a vector of parameters to check whether they are suitable for separation of...
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Tuning a Hybrid GPU-CPU V-Cycle Multilevel Preconditioner for Solving Large Real and Complex Systems of FEM Equations
PublicationThis letter presents techniques for tuning an accelerated preconditioned conjugate gradient solver with a multilevel preconditioner. The solver is optimized for a fast solution of sparse systems of equations arising in computational electromagnetics in a finite element method using higher-order elements. The goal of the tuning is to increase the throughput while at the same time reducing the memory requirements in order to allow...
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The influence of climate change on the life insurance in the EU: A panel data approach
PublicationThe financial sector, as one of the most sensitive economic sectors, is alert to all trends and changes in the environment. The aim of the article is to study the impact of climate change on the life insurance market using panel data from 28 countries of the European Union (EU) for the last 9 years. This study is based on a panel model, where the amount of premiums under life insurance contracts is defined as a function of the...