Search results for: DISCRETE WAVELET TRANSFORM
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Conley-Morse graphs for a population model with harvesting. Case Hj-S1: Harvesting juveniles only, survival rates of juveniles and adults add up to 1
Open Research DataThis dataset contains selected results of rigorous numerical computations conducted in the framework of the research described in the paper "Global dynamics in a stage-structured discrete population model with harvesting" by E. Liz and P. Pilarczyk: Journal of Theoretical Biology, Vol. 297 (2012), pp. 148–165, doi: 10.1016/j.jtbi.2011.12.012.
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Conley-Morse graphs for a population model with harvesting. Case Ha-S1: Harvesting adults only, survival rates of juveniles and adults add up to 1
Open Research DataThis dataset contains selected results of rigorous numerical computations conducted in the framework of the research described in the paper "Global dynamics in a stage-structured discrete population model with harvesting" by E. Liz and P. Pilarczyk: Journal of Theoretical Biology, Vol. 297 (2012), pp. 148–165, doi: 10.1016/j.jtbi.2011.12.012.
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Conley-Morse graphs for a population model with harvesting. Case Ha-Se: Harvesting adults only, equal survival rates of juveniles and adults
Open Research DataThis dataset contains selected results of rigorous numerical computations conducted in the framework of the research described in the paper "Global dynamics in a stage-structured discrete population model with harvesting" by E. Liz and P. Pilarczyk: Journal of Theoretical Biology, Vol. 297 (2012), pp. 148–165, doi: 10.1016/j.jtbi.2011.12.012.
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Integration and verification of meteorological observations and NWP model data for the local GNSS tomography
PublicationGNSS meteorology applies the Global Navigation Satellite Systems (GNSS) to derive information about the state of the atmosphere (particularly troposphere). The tomography is one of the methods used in GNSS meteorology. The input data of GNSS tomography are the signal troposphere delays, results of GNSS data processing and additionally meteorological observations and Numerical Weather Prediction (NWP) models data. Different types...
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Reclaimed Rubber/Poly(ε‐caprolactone) Blends: Structure, Mechanical, and Thermal Properties
PublicationThe amount of elastomeric waste, especially from tires is constantly increasing on a global scale. The recycling of these residua should be considered a priority. Compounding the waste rubbers with other polymers can be an excellent alternative to reuse waste materials. This procedure requires solving the issue of the lack of compatibility between the waste rubber particles and other polymers. Simultaneously, there is a claim for...
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Insights into Compatibilization of Poly(ε-caprolactone)-based Biocomposites with Diisocyanates as Modifiers of Cellulose Fillers
PublicationThis study aimed to analyze the impact of cellulose fillers’ modification with diisocyanates on the performance of composites based on the poly(ε-caprolactone) (PCL) matrix. Four most commonly used diisocyantes (isophorone, hexamethylene, toluene, and methylene diphenyl) were applied as modifiers of cellulose fillers (5 and 15 wt% per mass of filler). Modified fillers were introduced in the amount of 30 wt% into the PCL matrix....
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Roughness evaluation of turned composite surfaces by analysis of the shape of Autocorrelation Function
PublicationIn this paper, the application of an Autocorrelation Function for the characterisation of surface topography was validated. The roughness evaluation of turned composite surfaces was supported by sophisticated studies of the Autocorrelation Function properties, considering especially the shape of the function. Details were measured with the optical method. The selection of the surface roughness evaluation procedures was carried...
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A Comprehensive Analysis of Impedance of the Electrochemical Cell
PublicationA comprehensive impedance characteristics of two electrodes electrochemical cell has been pre sented. In this method a multisinusoidal current excitation signal is used. The change of potential of both the electrodes are all registered as a function of time. The proposed method gives the possibility of determining the impedance of both electrodes individually as well as the impedance of a twoelectrode system. Additional application...
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Chemical composition, antioxidant and anticancer effects of the seeds and leaves and indigo (polygonum tinctorium Ait.) Plant
PublicationSeeds and leaves of indigo (Polygonum tinctorium Ait.) plant were investigated and compared with another medicinal plant named prolipid for their properties such as chemical composition, antioxidant, and anticancer effects by Fourier transform infrared, three-dimensional fluorescence spectroscopy, and electrospray ionization-MS in negative mode. It was found that polyphenols, flavonoids, and flavanols were significantly higher...
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Fast High-Impedance Spectroscopy Method Using SINC Signal Excitation
PublicationIn this paper the method of fast impedance spectroscopy of technical objects with high impedance (|Zx| > 1 Gohm) is evaluated by means of simulation and practical experiment. The method is based on excitation of an object with a sinc signal and sampling response signals proportional to current flowing through and voltage across the measured impedance. The object impedance spectrum is obtained with use of continuous Fourier transform...
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Structural and luminescence properties of B2O3-Bi2O3-AlF3 glass doped with Eu3+, Tb3+ and Tm3+ ions
PublicationThe B2O3-Bi2O3-AlF3 glass system doped with Eu3+, Tb3+, Tm3+ and triply doped with Eu3+/Tm3+/Tb3+ ions in different molar ratios were successfully synthesized. Glass transition and crystallization temperatures were examined by Differential Scanning Calorimetry (DSC) measurements. X-ray Diffraction (XRD) confirmed the amorphous character of the samples. Fourier Transform Infrared Spectroscopy (FTIR) revealed that the glass matrix...
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Jeffreys heat conduction in coupled semispaces subjected to interfacial heating
PublicationA Jeffreys heat conduction problem for coupled semispaces subjected to the action of an interfacial heat source was defined. An analytical solution of the problem was derived for a polynomial specific power of the heat source using the Laplace transform approach. The asymptotic and parametric analysis was performed for different ratios of thermal conductivities , thermal diffusivities , thermal relaxation times and coefficients...
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Analytical Study of Sliding Instability due to Velocity- and Temperature-Dependent Friction
PublicationThe 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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HISTORY OF INITIAL ENERGY AND WATER NETWORK DEVELOPMENT IN QATAR
PublicationQatar: A country which had to be associated with neighboring countries like UAE or Saudi Arabia for people to know about it, stands proud today due to the ample production and exporting of Black Gold. A country with almost no vegetation or suitable weather to harvest crops, turned from being heavily dependent on trading Pearls to exporting natural oil and gas to all over the globe. The paper outlines in details the history of the...
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Structure-rheology relationship of fully bio-based linear polyester polyols for polyurethanes - Synthesis and investigation
PublicationThe synthesis of polyols from renewable substances as an alternative for petrochemical-based polyols play important matter in the polyurethane industry. In this work, the fully bio-based linear polyester polyols with different catalyst amounts were synthesized via two-step polycondensation method. The effect of various catalyst content on the structure and rheological behavior were established. Fourier Transform Infrared Spectroscopy,...
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Analyzing energy/performance trade-offs with power capping for parallel applications on modern multi and many core processors
PublicationIn the paper we present extensive results from analyzing energy/performance trade-offs with power capping observed on four different modern CPUs, for three different parallel applications such as 2D heat distribution, numerical integration and Fast Fourier Transform. The CPU tested represent both multi-core type CPUs such as Intel⃝R Xeon⃝R E5, desktop and mobile i7 as well as many-core Intel⃝R Xeon PhiTM x200 but also server, desktop...
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Determination of modifier contents in polymer-modified bitumens and in samples collected from the roads using high performance gel permeation/size exclusion chromatography
PublicationThis paper describes application of high performance gel permeation/size exclusion chromatography (HP-GPC/SEC) for the determination of content of polymer modifiers in modified road bitumens. The obtained results were compared with the measurements based on the procedure recommended by the American Association of State Highway and Transportation Officials, which employs Fourier transform mid-infrared spectroscopy (mid-IR FTIR)....
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Improvement of opipramol base solubility by complexation with β-cyclodextrin
PublicationOpipramol (OPI), a tricyclic antidepressant and anxiolytic compound, is administered orally in the form of a dihydrochloride. Salt form of the drug has a higher solubility in water and hence bioavailability and stability. A similar effect can be achieved by closing the hydrophobic part of the drug molecule in the cyclodextrin cavity. The paper presents opipramol inclusion complexes with beta-cyclodextrin (β-CD) in 1:1 molar ratio....
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Chemical modifications of graphene and their influence on properties of polyurethane composites: a review
PublicationPolyurethane composites are materials of great interest nowadays due to their wide range of available forms and applications in industry. Controlling and achieving unique properties via matrix modifications and addition of various specific nanofillers seems be one of the key elements to success. The purpose of this work is to briefly present some examples of graphene nanoderivatives, their syntheses, properties and influence on...
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Physico‐Mechanical Properties and Flammability of PUR/PIR Foams Containing Expandable Graphite Core‐Shell Composite Particles
PublicationIn this work, polyurethane/polyisocyanurate (PUR/PIR) foams were modified by two types of expandable graphite (EG) core-shell composite particles. The pulverized EG core-shell composite particles were prepared during emulsion polymerization using methyl methacrylate or glycidyl methacrylate for the synthesis of the polymeric shells (poly(methyl methacrylate) (PMMA) and poly (glycidyl methacrylate) (PGMA)), and then the obtained EG_PMMA...
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Shear band evolution phenomena in direct shear test modelled with DEM.
PublicationA direct shear test is widely used in the geotechnical engineering field. It is an easy and quick test to measure the shear properties of soil. This test often replaces more expensive and difficult tri-axial shear test. Despite that the direct shear test is known and used for a long time, it is still not well investigated at the grain scale. This paper deals with the micro behaviour of the cohesionless sand inside the direct shear...
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Average Redundancy of the Shannon Code for Markov Sources
PublicationIt is known that for memoryless sources, the average and maximal redundancy of fixed–to–variable length codes, such as the Shannon and Huffman codes, exhibit two modes of behavior for long blocks. It either converges to a limit or it has an oscillatory pattern, depending on the irrationality or rationality, respectively, of certain parameters that depend on the source. In this paper, we extend these findings, concerning the Shannon...
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The model of end-to-end call setup time calculation for Session Initiation Protocol
PublicationEnd-to-end call setup delay is one of the most important grade of service (GoS) parameters for VoIP networks with Session Initiation Protocol (SIP). A typical subscriber wants to have a connection established as soon as possible. From the operator's perspective call setup time is also crucial because he needs to know how probability of successful packet transmission on SIP links is related to a call setup delay. Then he can make...
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Optimal spindle speed determination for vibration reduction during ball-end milling of flexible details
PublicationIn the paper a method of optimal spindle speed determination for vibration reduction during ball-end milling of flexible details is proposed. In order to reduce vibration level, an original procedure of the spindle speed optimisation, based on the Liao–Young criterion, is suggested. As the result, an optimal, constant spindle speed value is determined. For this purpose, on-stationary computational model of machining process is...
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Comparison of Average Energy Slope Estimation Formulas for One-dimensional Steady Gradually Varied Flow
PublicationTo find the steady flow water surface profile, it is possible to use Bernoulli’s equation, which is a discrete form of the differential energy equation. Such an approach requires the average energy slope between cross-sections to be estimated. In the literature, many methods are proposed for estimating the average energy slope in this case, such as the arithmetic mean, resulting in the standard step method, the harmonic mean and...
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Pounding between Inelastic Three-Storey Buildings under Seismic Excitations
PublicationStructural interactions between adjacent, insufficiently separated buildings have been repeatedly observed during damaging ground motions. This phenomenon, known as the structural pounding, may result in substantial damage or even total collapse of structures. The aim of the present paper is to show the results of the nonlinear numerical analysis focused on pounding between inelastic three-storey buildings under seismic excitations....
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Sensing the onset of epoxy coating degradation with combined Raman spectroscopy/atomic force microscopy/electrochemical impedance spectroscopy
PublicationThe paper presents the results of investigation on epoxy resin durability upon 12-week exposure to UV radiation. The aim was early determination of the onset of epoxy degradation and for this purpose an epoxy film on steel substrate systems were periodically inspected using Raman spectroscopy, atomic force microscopy and electrochemical impedance spectroscopy. The behaviour of examined polymer could be divided into three periods: immunity,...
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An algorithm to generate high dense packing of particles with various shapes
PublicationDiscrete Element Method (DEM) is one of available numerical methods to compute movement of particles in large scale simulations. The method has been frequently applied to simulate the cases of grain or bulk material as the major research issue. The paper describes a new method of generating high dense packing with mixed material of two different shape used in DEM simulation. The initial packing is an important parameter to control,...
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A model of fuel combustion process in the marine reciprocating engine work space taking into account load and wear of crankshaft-piston assembly and the theory of semi-Markov processes
PublicationThe ar ticle analyses the operation of reciprocal internal combu stion engines, with mar ine engines u sed a s an example. The analysis takes into account types of energy conversion in the work spaces (cylinders) of these engines, loads of their crankshaft-piston assemblies, and types of fuel combustion which can take place in these spaces during engine operation. It is highlighted that the analysed time-dependent loads of marine...
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Towards solving heterogeneous fleet vehicle routing problem with time windows and additional constraints: real use case study
PublicationIn advanced logistic systems, there is a need for a comprehensive optimization of the transport of goods, which would reduce costs. During past decades, several theoretical and practical approaches to solve vehicle routing problems (VRP) were proposed. The problem of optimal fleet management is often transformed to discrete optimization problem that relies on determining the most economical transport routes for a number of vehicles...
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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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Micro-modelling of shear localization during quasi-static confined granular flow in silos using DEM
PublicationThe paper deals with the quasi-static confined flow of cohesionless sand in a plane strain model silo with parallel walls and a slowly movable bottom. Numerical modelling was carried out by the discrete element method (DEM) using spheres with contact moments to approximately capture a non-uniform shape of sand particles. Different initial void ratios of sand and silo wall roughness grades were employed. Regular triangular grooves...
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EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF CONCRETE BEHAVIOUR AT MESO-LEVEL DURING QUASI-STATIC SPLITTING TENSION
PublicationThe paper describes experimental and numerical results of quasi-static splitting tensile tests on concrete specimens at meso-scale level. The loading strip was made of plywood or steel. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: 3D x-ray micro-computed tomography, 2D scanning electron microscope and manual 2D digital microscope. The discrete element method was used to directly...
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A constitutive law for concrete with smooth transition from continuous into discontinuous cracks’ description
PublicationPaper presents a constitutive model for concrete that combines a continuous and discontinuous crack’s description to simulate the concrete under tensile dominated loads. In a continuum regime, two different constitutive laws were used. First, a plasticity model with the Rankine failure criterion and an associated flow rule was used. Second, a constitutive law based on isotropic damage mechanics was formulated. Both model alternatives...
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Simulations of hydro-fracking in rock mass at meso-scale using fully coupled DEM/CFD approach
PublicationThe paper deals with two-dimensional (2D) numerical modelling of hydro-fracking (hydraulic fracturing) in rocks at the meso-scale. A numerical model was developed to characterize the properties of fluid-driven fractures in rocks by combining the discrete element method (DEM) with computational fluid dynamics (CFD). The mechanical behaviour of the rock matrix was simulated with DEM and the behaviour of the fracturing fluid flow...
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Subharmonic solutions for a class of Lagrangian systems
PublicationWe prove that second order Hamiltonian systems with a potential of class C1, periodic in time and superquadratic at infinity with respect to the space variable have subharmonic solutions. Our intention is to generalise a result on subharmonics for Hamiltonian systems with a potential satisfying the global Ambrosetti-Rabinowitz condition from [P. H. Rabinowitz, Proc. Roy. Soc. Edinburgh Sect. A, 114 (1990), 33-38]. Indeed, we weaken...
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The Arnold conjecture in $ \mathbb C\mathbb P^n $ and the Conley index
Publicationn this paper we give an alternative, purely Conley index based proof of the Arnold conjecture in CP^n asserting that a Hamiltonian diffeomorphism of CP^n endowed with the Fubini-Study metric has at least (n+1) fixed points.
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Wild oscillations in a nonlinear neuron model with resets: (I) Bursting, spike-adding and chaos
PublicationIn a series of two papers, we investigate the mechanisms by which complex oscillations are generated in a class of nonlinear dynamical systems with resets modeling the voltage and adaptation of neurons. This first paper presents mathematical analysis showing that the system can support bursts of any period as a function of model parameters, and that these are organized in a period-incrementing structure. In continuous dynamical...
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Detecting coupling directions with transcript mutual information: A comparative study
PublicationCausal relationships are important to understand the dynamics of coupled processes and, moreover, to influence or control the effects by acting on the causes. Among the different approaches to determine cause-effect relationships and, in particular, coupling directions in interacting random or deterministic processes, we focus in this paper on information-theoretic measures. So, we study in the theoretical part the difference between...
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Mieszanie w klasie niejednorodnych łańcuchów Markowa i kwadratowych operatorów stochastycznych
PublicationRozprawa doktorska poświęcona jest zagadnieniu asymptotycznych własności w klasie nieskończenie wymiarowych niejednorodnych łańcuchów Markowa z czasem dyskretnym oraz w klasie kwadratowych operatorów stochastycznych. W pierwszej kolejności definiowane są różne rodzaje asymptotycznego zachowania (mieszania) niejednorodnych łańcuchów Markowa odpowiadające zbieżności w normowej i mocnej topologii operatorowej oraz omówione są relacje...
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The low-frequency magnetic field emissions on-board of the vessel
Open Research DataThe data represents measurement results performed on board of the vessel. The acquired time-waveforms, corresponding to the instantaneous values of the magnetic field (MF) induction were acquired near the cable supplying the bow thruster motor. Data recording of the magnetic field density (MFD) emissions was carried out with a/d converters of the data...
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Isolation and structure of a covalent cross-link adduct between mitomycin C and DNA
PublicationA DNA cross-link adduct of the antitumor agent mitomycin C (MC) to DNA has been isolated and characterized; the results provide direct proof for bifunctional alkylation of DNA by MC. Exposure of MC to Micrococcus luteus DNA under reductive conditions and subsequent nuclease digestion yielded adducts formed between MC and deoxyguanosine residues. In addition to the two known monoadducts, a bisadduct was obtained. Reductive MC activation...
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Artificial intelligence in architectural education - green campus development research
PublicationThe rapid advancement of artificial intelligence (AI) technologies has introduced new possibilities and challenges in design education. This article explores the need for changes and adaptations in the teaching process of design as AI-related technologies, based on image generation, transform the creative process and offer novel opportunities. In a research-by-design studio in an architectural faculty in Poland, students who utilised...
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Properties of Different Varieties of Durian
PublicationDurian (Durio zibethinus Murr.), like many other exotic, tropical, and conventional fruits, is important in the prevention of different diseases. In this study, the characterization of the main bioactive compounds of the most popular cultivars of durian and their properties are described. The changes in the quality indices of the antioxidant status were determined by CUPRAC, ABTS, FRAP, DPPH, and ORAC assays. The profiling of phytochemicals...
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Nonlocalized thermal behavior of rotating micromachined beams under dynamic and thermodynamic loads
PublicationRotating micromachined beams are one of the most practical devices with several applications from power generation to aerospace industries. Moreover, recent advances in micromachining technology have led to huge interests in fabricating miniature turbines, gyroscopes and microsensors thanks to their high quality/reliability performances. To this end, this article is organized to examine the axial dynamic reaction of a rotating...
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Challenges for universities in the face of knowledge-based economy - directions for higher education institutions in the Baltic Sea Region
PublicationThe aim of this paper is to present new challenges that are faced by universities in the knowledge-based economy. There are several phenomena that can presently be observed like the need for life-long learning or interdisciplinary approach, and universities should prepare their graduates for those challenges. One of the crucial questions that universities need to ask is how to teach and what to teach. Knowledge becomes obsolete...
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Challenges for universities in the face of the knowledge-based economy - Directions for higher education institutions in the Baltic Sea Region
PublicationThe aim of this paper is to present new challenges that are faced by universities in the knowledge-based economy. There are several phenomena that can presently be observed like the need for life-long learning or interdisciplinary approach, and universities should prepare their graduates for those challenges. One of the crucial questions that universities need to ask is how to teach and what to teach. Knowledge becomes obsolete...
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Modification of thermal and rheological characteristics of bitumen by waste PET/GTR blends
PublicationWaste poly(ethylene terephthalate) (wPET)/ground tire rubber (GTR) blends with variable compositions were applied as low-cost modifiers into bitumen and their performance has been evaluated via morphological, thermal and rheological analyses. Depending on the weight ratio of wPET/GTR, dispersion of single/composite domains of waste polymers in the bitumen has promoted the interaction between bitumen and blend components. Fourier...
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Softwood-lignin/natural rubber composites containing novel plasticizing agent: Preparation and characterization
PublicationComposite materials based on natural rubber were obtained by using glycerolysate (decomposition prod- uct of polyurethane) as a novel plasticizer. In order to determine the effect of various lignin content, four different filler amounts were used, namely, 5 phr (parts per 100 parts of natural rubber) of lignin (WLI5G), 10 phr (WLI10G), 20 phr (WLI20G), and 40 phr (WLI40G). The reference specimen without lignin (WLI0G) was also...
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An investigation on the role of GMA grafting degree on the efficiency of PET/PP-g-GMA reactive blending: morphology and mechanical properties
PublicationGlycidyl methacrylate (GMA) has been grafted on polypropylene (PP) with the aid of styrene (St) comonomer, by changing dicumyl peroxide initiator content, GMA level, and St concentration. The performance of the resulting PP-g-GMA reactive material towards static and dynamic mechanical properties of poly (ethylene terephthalate) (PET) was monitored in terms of grafting reaction variables and compatibilizer content. Fourier transform...