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Wyniki wyszukiwania dla: DYNAMIC EQUATION
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Parallel implementation of the DGF-FDTD method on GPU Using the CUDA technology
PublikacjaThe discrete Green's function (DGF) formulation of the finite-difference time-domain method (FDTD) is accelerated on a graphics processing unit (GPU) by means of the Compute Unified Device Architecture (CUDA) technology. In the developed implementation of the DGF-FDTD method, a new analytic expression for dyadic DGF derived based on scalar DGF is employed in computations. The DGF-FDTD method on GPU returns solutions that are compatible...
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Verification of Formulas for Periods of Adjacent Buildings Used to Assess Minimum Separation Gap Preventing Structural Pounding during Earthquakes
PublikacjaInsufficient separation distance between adjacent buildings may lead to serious damages during earthquakes due to structural pounding. The best way to prevent collisions is to provide sufficiently large separation distance between the structures. In this paper, the periods of two closely-spaced linear and nonlinear buildings have been investigated so as to accurately assess the minimum in-between separation gap. A new equation...
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RANS-based design optimization of dual-rotor wind turbines
PublikacjaPurpose An improvement in the energy efficiency of wind turbines can be achieved using dual rotors. Because of complex flow physics, the design of dual-rotor wind turbines (DRWTs) requires repetitive evaluations of computationally expensive partial differential equation (PDE) simulation models. Approaches for solving design optimization of DRWTs constrained by PDE simulations are investigated. The purpose of this study is to determine...
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Testing Stability of Digital Filters Using Optimization Methods with Phase Analysis
PublikacjaIn this paper, novel methods for the evaluation of digital-filter stability are investigated. The methods are based on phase analysis of a complex function in the characteristic equation of a digital filter. It allows for evaluating stability when a characteristic equation is not based on a polynomial. The operation of these methods relies on sampling the unit circle on the complex plane and extracting the phase quadrant of a function...
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Effects of social media communication on brand equity and brand purchase intention
PublikacjaThe author studied the effect of two different social media communication on brand equity and brand purchase intention. A total of 504 data sets were generated through a standardized online-survey and analysed with structural equation modeling. The results of the empirical study showed that both firm-created and user-generated social media communication influenced brand equity, consequently impacting brand purchase intention. This...
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Relativity of arithmetic as a fundamental symmetry of physics
PublikacjaArithmetic operations can be defined in various ways, even if one assumes commutativity and associativity of addition and multiplication, and distributivity of multiplication with respect to addition. In consequence, whenever one encounters ‘plus’ or ‘times’ one has certain freedom of interpreting this operation. This leads to some freedom in definitions of derivatives, integrals and, thus, practically all equations occurring in...
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Flow structure, heat transfer and scaling analysis in the case of thermo-magnetic convection in a differentially heated cylindrical enclosure
PublikacjaThe experimental, numerical and scaling analysis in the case of thermo-magnetic convection in a thermosyphon-like enclosure filled with a paramagnetic fluid is presented. Visualization of temperature field together with the numerical simulation gave an information about the flow structure, which indicated “finger-like” structures of hot and cold streams advecting each other. Their number depended on the Rayleigh number and also...
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Determinants of the Internationalization of Family Firms - a Structural Eqquation Modeling Analysis
PublikacjaCurrently, international behaviors of family businesses (FBs) attract a growing interest of researchers. In an increasingly competitive environment, numerous FBs are forced to expand into foreign markets in search for ways to survive or grow. The article is both theoretical and empirical. In the theoretical part it presents theoretical concepts of FBs internationalization, especially determinants for their going international....
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Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines. Part I: Steady-state processes
PublikacjaThe article presents a possible method of detecting failures in the flow section and supply system of a naval gas turbine engine based on the exhaust gas temperature measured behind the gas generator. This temperature is a basic diagnostic parameter use for evaluating the technical state of the turbine engine in operation, and is monitored during engine start-ups, accelerations and decelerations of rotor units, and steady-load...
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Modified Preisach model of hysteresis in multi air gap ferrite core medium frequency transformer
PublikacjaThis article presents the modified Preisach model of hysteresis for a 3-phase medium frequency transformer in a 100 kW dual active bridge converter. The transformer magnetic core is assembled out of ferrite I-cores, which results in multiple parasitic air gaps. For this transformer, the hysteresis loops were measured and parameters of the Preisach model were determined. The Preisach distribution function is approximated with a...
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MEMORY EFFECT ANALYSIS USING PIECEWISE CUBIC B-SPLINE OF TIME FRACTIONAL DIFFUSION EQUATION
PublikacjaThe purpose of this work is to study the memory effect analysis of Caputo–Fabrizio time fractional diffusion equation by means of cubic B-spline functions. The Caputo–Fabrizio interpretation of fractional derivative involves a non-singular kernel that permits to describe some class of material heterogeneities and the effect of memory more effectively. The proposed numerical technique relies on finite difference approach and cubic...
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FPGA Acceleration of Matrix-Assembly Phase of RWG-Based MoM
PublikacjaIn this letter, the field-programmable-gate-array accelerated implementation of matrix-assembly phase of the method of moments (MoM) is presented. The solution is based on a discretization of the frequency-domain mixed potential integral equation using the Rao-Wilton-Glisson basis functions and their extension to wire-to-surface junctions. To take advantage of the given hardware resources (i.e., Xilinx Alveo U200 accelerator card),...
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Diffusion equations with spatially dependent coefficients and fractal Cauer-type networks
PublikacjaIn this article, we formulate and solve the representation problem for diffusion equations: giving a discretization of the Laplace transform of a diffusion equation under a space discretization over a space scale determined by an increment h > 0, can we construct a continuous in h family of Cauer ladder networks whose constitutive equations match for all h > 0 the discretization. It is proved that for a finite differences discretization...
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Minimal parameter implicit solvent model for ab initioelectronic-structure calculations
PublikacjaAbstract - We present an implicit solvent model for ab initio electronic-structure calculations which is fully self-consistent and is based on direct solution of the nonhomogeneous Poisson equation. The solute cavity is naturally defined in terms of an isosurface of the electronic density according to the formula of Fattebert and Gygi (J. Comput. Chem., 23 (2002) 662). While this model depends on only two parameters, we demonstrate...
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Valence and lowest Rydberg electronic states of phenol investigated by synchrotron radiation and theoretical methods
PublikacjaWe present the experimental high-resolution vacuum ultraviolet (VUV) photoabsorption spectra of phenol covering for the first time the full 4.3–10.8 eV energy-range, with absolute cross sections determined. Theoretical calculations on the vertical excitation energies and oscillator strengths were performed using time-dependent density functional theory and the equation-of-motion coupled cluster method restricted to single and double...
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Solving Boundary Value Problems for Second Order Singularly Perturbed Delay Differential Equations by ε-Approximate Fixed-Point Method
PublikacjaIn this paper, the boundary value problem for second order singularly perturbed delay differential equation is reduced to a fixed-point problem v = Av with a properly chosen (generally nonlinear) operator A. The unknown fixed-point v is approximated by cubic spline vh defined by its values vi = vh(ti) at grid points ti, i = 0, 1, ... ,N. The necessary for construction the cubic spline and missing the first derivatives at the boundary...
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Quantifying wage effects of offshoring: import- versus export-based measures of production fragmentation
PublikacjaIn this paper we examine the implications of international fragmentation of production on wages in the light of recent methodological developments in offshoring measurement. In particular, we compare the results stemming from two ways of quantifying offshoring – the traditional one based on import statistics and the one obtained from the decomposition of gross exports and input-output information. In the empirical part of our study,...
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Brand loyalty creation in the social network. Does the product category matter?
PublikacjaThe final goal of all marketers’ effort is to achieve a high level of loyalty toward their brands. Social network brand sites are increasingly attracting the attention of scientists and managers intrigued by their potential application for brand loyalty creation. The aim of this research, based on European sample, is to fill the gap in understanding the product category loyalty and brand loyalty relation as an output of brand identification...
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Determination of dryout localization using a five-equation model of annular flow for boiling in minichannels
PublikacjaDetailed studies have suggested that the critical heat flux in the form of dryout in minichannels occurs when the combined effects of entrainment, deposition, and evaporation of the film make the film flow rate go gradually and smoothly to zero. Most approaches so far used the mass balance equation for the liquid film with appropriate formulations for the rate of deposition and entrainment respectively. It must be acknowledged...
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Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
PublikacjaThe results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 104 Ra 1.3 106 and the Prandtl (Pr) number varied from 4.4 to 176....
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Effect of Axial Porosities on Flexomagnetic Response of In-Plane Compressed Piezomagnetic Nanobeams
PublikacjaWe investigated the stability of an axially loaded Euler–Bernoulli porous nanobeam considering the flexomagnetic material properties. The flexomagneticity relates to the magnetization with strain gradients. Here we assume both piezomagnetic and flexomagnetic phenomena are coupled simultaneously with elastic relations in an inverse magnetization. Similar to flexoelectricity, the flexomagneticity is a size-dependent property. Therefore,...
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Comparative Study of Integer and Non-Integer Order Models of Synchronous Generator
PublikacjaThis article presents a comparison between integer and non-integer order modelling of a synchronous generator, in the frequency domain as well as in the time domain. The classical integer order model was compared to one containing half -order systems. The half-order systems are represented in a Park d-q axis equivalent circuit as impedances modelled by half-order transmittances. Using a direct method based on the approximation...
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Analysis of a caustic formed by a spherical reflector: Impact of a caustic on architectural acoustics
PublikacjaFocusing sound in rooms intended for listening to music or speech is an acoustic defect. Design recommendations provide remedial steps to effectively prevent this. However, there is a category of objects of high historical or architectural value in which the sound focus correction is limited or even abandoned. This also applies to indoor or outdoor concert shells, installations for teaching and acoustic presentations, etc. The...
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Corporate social responsibility practices incomes and outcomes: Stakeholders' pressure, culture, employee commitment, corporate reputation, and brand performance. A Polish–German cross‐country study
PublikacjaThis study aims to compare employee perception of corporate social responsibility (CSR) practice incomes and outcomes in the construction industry in Poland and Germany. It proposes a model that examines the influence of stakeholder pressure, culture, and CSR practices on company brand performance, reputation, and employee identification. The findings suggest that the structure of relationships varies for project‐managed construction...
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Discrete-continuous optimisation of an axial flow blood pump
PublikacjaThis paper presents results of discrete-continuous optimisation of an axial flow blood pump. Evolution Strategies (ES) are used as a global optimisation method in order to localise the optimal solution in relatively short time. The whole optimisation process is fully automated. This also applies to geometry modelling. Numerical simulations of the flow inside the pump is performed by means of the Reynolds-Average Navier-Stokes...
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Removal efficiency of phenol by ozonation process with calcium peroxide from aqueous solutions
PublikacjaPhenol has been introduced as a priority pollutant by the US Environmental Protection Agency. Advanced oxidation processes (AOPs) are one of the most efcient methods for removal of non-degradable organic pollutants in aqueous solutions. The removal efciencies of phenol and COD under optimal conditions pH=3, phenol concentration=5 mg/L, CaO2 concentration=0.025 mg/L, temperature 25 °C, 1 g/min ozonation rate and contact time=90...
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Determination of equivalent axle load factors with the use of strain energy of distortion
PublikacjaThe paper proposes a new method for calculation of equivalent axle load factors based on the analysis of strain energy of distortion induced in road pavements by traffic loads. The main advantage of the method is the more accurate calculation of the effects of multiple axles and super single versus dual tyres. The methodconsiders the location of critical points, at which strain energy of distortion reaches extreme values. When...
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Thermodynamic study of binary mixtures of 2-propanol with ionic liquids, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate and triethylhexylammonium bis(trifluoromethylsulfonyl)imide
PublikacjaIn this work, densities, speeds of sound, refractive indices and viscosities of three binary mixtures containing the ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)imide, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate and triethylhexyl-ammonium bis(trifluoromethylsulfonyl)imide, mixed with 2-propanol at wide temperature and composition ranges at atmospheric pressure have been measured. From these...
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The Discrete-Continuous, Global Optimisation of an Axial Flow Blood Pump
PublikacjaThis paper presents the results of the discrete-continuous optimisation of an axial flow blood pump. Differential evolution (DE) is used as a global optimisation method in order to localise the optimal solution in a relatively short time. The whole optimisation process is fully automated. This also applies to geometry modelling. Numerical simulations of the flow inside the pump are performed by means of the Reynolds-Average Navier-Stokes...
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Computationally Effcient Solution of a 2D Diffusive Wave Equation Used for Flood Inundation Problems
PublikacjaThis paper presents a study dealing with increasing the computational efficiency in modeling floodplain inundation using a two-dimensional diffusive wave equation. To this end, the domain decomposition technique was used. The resulting one-dimensional diffusion equations were approximated in space with the modified finite element scheme, whereas time integration was carried out using the implicit two-level scheme. The proposed...
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Market orientation and hotel performance: The mediating effect of creative marketing programs
PublikacjaThis work investigates the indirect effects between market orientation and hotel performance through creative marketing programs. The focus is on exploring the indirect effects between 1) customer orientation, competitor orientation, and cross-functional integration; and 2) hotel financial performance through two aspects of creative marketing programs, namely, novelty and meaningfulness. Through an empirical analysis using structural equation...
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Magnetoacoustic Heating in Nonisentropic Plasma Caused by Different Kinds of Heating-Cooling Function
PublikacjaThe nonlinear phenomena which associate with magnetoacoustic waves in a plasma are analytically studied. A plasma is an open system with external inflow of energy and radiation losses. A plasma’s flow may be isentropically stable or unstable. The nonlinear phenomena occur differently in dependence on stability or instability of a plasma’s flow. The nonlinear instantaneous equation which describes dynamics of nonwave entropy mode...
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The linkage between knowledge risk management and organizational performance
PublikacjaThe purpose of this study is to examine the effect of knowledge risk management (KRM) on organizational performance, with measures considered as “softer” measures of performance, i.e. innovativeness, responsiveness, sustainability, and agility. Data were collected using an online questionnaire sent to private and public orga- nizations located all over the world. The analysis and hypotheses testing were performed using structural...
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Crank–Nicolson FDTD Method in Media Described by Time-Fractional Constitutive Relations
PublikacjaIn this contribution, we present the Crank-Nicolson finite-difference time-domain (CN-FDTD) method, implemented for simulations of wave propagation in media described by time-fractional (TF) constitutive relations. That is, the considered constitutive relations involve fractional-order (FO) derivatives based on the Grünwald-Letnikov definition, allowing for description of hereditary properties and memory effects of media and processes....
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Simulating coherent light propagation in a random scattering materials using the perturbation expansion
PublikacjaMultiple scattering of a coherent light plays important role in the optical metrology. Probably the most important phenomenon caused by multiple scattering are the speckle patterns present in every optical imaging method based on coherent or partially coherent light illumination. In many cases the speckle patterns are considered as an undesired noise. However, they were found useful in various subsurface imaging methods such as...
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Use of structural equation modeling in quantitative research in the field of management and economics: A bibliometric analysis in the systematic literature review
PublikacjaPURPOSE: This paper aims to provide a comprehensive review of scholarly research focusing on using quantitative methods and particularly structural equation modeling (SEM) in management and economics studies, as well as provide a bibliometric agenda including the time horizon of individual publications, the highest citation rate, geographic and industry areas, methodological context, and keywords. METHODOLOGY: A systematic literature...
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Impact of diffusion coefficient averaging on solution accuracy of the 2D nonlinear diffusive wave equation for floodplain inundation
PublikacjaIn the study, the averaging technique of diffusion coefficients in the two-dimensional nonlinear diffusive wave equation applied to the floodplain inundation is presented. As a method of solution, the splitting technique and the modified finite element method with linear shape functions are used. On the stage of spatial integration, it is often assumed that diffusion coefficient is constant over element and equal to its average...
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Pressure-induced phase transitions in LnTe (Ln=La, Gd, Ho, Yb) and AmTe
PublikacjaThe structural behaviour under compression of different lanthanide (La, Gd, Ho, Yb) and actinide (Am) monochalcogenides is studied by means of in situ high-pressure x-ray diffraction. All the investigated compounds crystallize at ambient conditions within a cubic (B1) NaCl-type structure but show different behaviours at high pressures. LaTe and AmTe undergo B1 to B2 (CsCl-type structure) phase transitions, starting at 9 GPa and...
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User-generated images and its impact on consumer-based brand equity and on purchase intention
PublikacjaResearchers and brand managers have limited knowledge of the effects that different types of user-generated content (UGC) have on consumers’ perception of brands and behavior. In this study we investigated 301 authors of a specific category of UGC, i.e., user-generated images (UGI) on a social networking site to confirm the relationships of four drivers reported in literature (co-creation, empowerment, community, and self-concept)...
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Acoustic streaming caused by some types of aperiodic sound. Buildup of acoustic streaming
PublikacjaThe analysis of streaming caused by aperiodic sound of different types (switched on at transducer sound or sound determined by initial conditions) is undertaken. The analysis bases on analytical governing equation for streaming Eulerian velocity, which is a result of decomposition of the hydrodynamic equations into acoustic and non-acoustic parts. Its driving force (of acoustic nature) represents a sum of two terms; one is the...
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Solvation of ionic liquids based on N -methyl- N -alkylmorpholinium cations in N,N -dimethylformamide and N,N -dimethylacetamide – Volumetric and compressibility studies
PublikacjaDensity and sound velocity of the solutions of ionic liquids based on N-alkyl-N-methyl- morpholinium cations: N-ethyl- -methylmorpholinium bis(trifluoromethanesulfonyl)imide, N-butyl-Nmethylmorpholinium bis(trifluoromethanesulfonyl)imide, N-octyl-N-methyl -morpholinium bis(trifluor omethanesulfonyl)imide and N-decyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide in N, N-dimethylformamide and N,N-dimethylacetamide were...
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Electronic structure and rovibrational predissociation of the 2^1Π state in KLi
PublikacjaAdiabatic potential energy curves of the 3^1Σ^+, 3^3Σ^+, 2^1Π and 2^3Π states correlating for large internuclear distance with the K(4s) + Li(2p) atomic asymptote were calculated. Very good agreement between the calculated and the experimental curve of the 2^1Π state allowed for a reliable description of the dissociation process through a small (∼20 cm−1 for J = 0) potential energy barrier. The barrier supports several rovibrational...
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Assessing groundwater vulnerability to pollution in the Puck region (denudation moraine upland) using vertical seepage method
PublikacjaDegradation of groundwater quality can cause a serious water supply and environmental problems. The identify of potential groundwater pollution can be determined by assessment of groundwater vulnerability method. The assessment of groundwater vulnerability to pollution was based on estimation of migration time of potential conservative contamination through the vadose zone. Area of investigation is a type of denudation moraine...
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Social Capital, Human Capital, Tacit Knowledge, and Innovations: A Polish-US Cross-Country Study
PublikacjaThis study measures the relationship between human and social capital (internal and external) and tacit knowledge sharing's influence on innovativeness among knowledge workers employed in Polish (n=1050) and US (n=1118) organizations. The structural equation modeling method revealed that internal social capital matters more for organizational innovativeness in the US. In Poland, both external and internal were important. Specifically,...
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Analytical Study of Sliding Instability due to Velocity- and Temperature-Dependent Friction
PublikacjaThe instability of sliding causes deterioration of performance characteristics of tribosystems and is undesired. To predict its occurrence, the motion of a body of a one-degree-of-freedom system with friction is investigated about the steady sliding equilibrium position. The motion equation is formulated with the friction coefficient dependent on the sliding velocity and contact temperature changing due to transient heat conduction...
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Thermodynamic study of binary mixtures of toluene with ionic liquids, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-butylpyridinium bis(trifluoromethylsulfonyl)imide
PublikacjaDensities, refractive indices and viscosities at 293.15, 298.15, 303.15, 308.15 and 313.15 K of binary mixtures of toluene with 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-butylpyridinium bis(trifluoromethylsulfonyl)imide have been measured over the miscible region at p = 0.1 MPa. From the experimental data, values of excess molar volume,...
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Guessing Intrinsic Forwarding Trustworthiness of Wireless Ad Hoc Network Nodes
PublikacjaA novel node misbehavior detection system called GIFTED is proposed for a multihop wireless ad hoc network (WAHN) whose nodes may selfishly refuse to forward transit packets. The system guesses the nodes’ intrinsic forwarding trustworthiness (IFT) by analyzing end-to-end path performance rather than utilizing unreliable and incentive incompatible low-layer mechanisms. It can work with occasional IFT jumps, directional antennae,...
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On the Dynamics of a Visco–Piezo–Flexoelectric Nanobeam
PublikacjaThe fundamental motivation of this research is to investigate the effect of flexoelectricity on a piezoelectric nanobeam for the first time involving internal viscoelasticity. To date, the effect of flexoelectricity on the mechanical behavior of nanobeams has been investigated extensively under various physical and environmental conditions. However, this effect as an internal property of materials has not been studied when the...
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NON-LINEAR MASTIC CHARACTERISTICS BASED ON THE MODIFIED MSCR (MULTIPLE STRESS CREEP RECOVERY) TEST
PublikacjaMastic containing asphalt in its composition is an example of a viscoelastic material. It is an effective binder in asphalt. It consists of a filler (<0.063 mm) and asphalt mixed in the right proportions. Just like in asphalt, its response depends on the temperature level, the load and stress time. Changing the stress stiffness of the mastic affects the non-linear course of the stress-strain relationship. Modelling of the non-linear...
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Performance assessment of OpenMP constructs and benchmarks using modern compilers and multi-core CPUs
PublikacjaConsidering ongoing developments of both modern CPUs, especially in the context of increasing numbers of cores, cache memory and architectures as well as compilers there is a constant need for benchmarking representative and frequently run workloads. The key metric is speed-up as the computational power of modern CPUs stems mainly from using multiple cores. In this paper, we show and discuss results from running codes such as:...