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Wyniki wyszukiwania dla: COMPOSITE PANELS, DAMAGE MECHANICS, ELASTO-PLASTICITY, EPS FOAM, NON-LOCAL THEORY, REINFORCED CONCRETE, CRACK BAND APPROACH
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Recent Achievements in Constitutive Equations of Laminates and Functionally Graded Structures Formulated in the Resultant Nonlinear Shell Theory
PublikacjaThe development of constitutive equations formulated in the resultant nonlinear shell theory is presented. The specific features of the present shell theory are drilling rotation naturally included in the formulation and asymmetric measures of strains and stress resultants. The special attention in the chapter is given to recent achievements: progressive failure analysis of laminated shells and elastoplastic constitutive relation...
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Probing Local Structural Changes by Sharp Luminescent Infrared Nanophosphor for Application in Light-Emitting Diodes
PublikacjaCr3+-doped infrared phosphors are promising candidates for next-generation phosphor-converted infrared light-emitting diodes (LEDs) because they can, in principle, tune and convert the luminescence spectra from an LED chip. However, most studies focus on broad-band Cr3+-doped phosphors, and the control mechanism of Cr3+-doped phosphors with sharp line emissions remains ambiguous. Here, we report LiGa5(1–x)Al5xO8:Cr3+ phosphors...
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Highly Integrable Planar-structured Printed Circularly Polarized Antenna for Emerging Wideband Internet of Things Applications in the Millimeter-Wave Band
PublikacjaThis paper proposes a numerically and experimentally validated printed wideband antenna with a planar geometry for Internet of Things (IoT) applications. This design tackles the challenges associated with deploying IoT sensors in remote areas or across extensive geographical regions. The proposed design exploits a coplanar-waveguide-fed modified microstrip line monopole for excitation of circularly polarized waves radiating in...
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Assessment of crack resistance of ship steels according to SEP 1390 standard
PublikacjaThe aim of the study was to evaluate the weldability of E36 nd NVE-36 steels by bending test according to SEP 1390. In the case of the specimen from E36 steel 9 external cracks were found, 5 of which were stopped in the fusion line and 4 in heat affected zone. In the case of the specimen from NVE-36 steel 8 external cracks were found, 4 of which were stopped in the fusion line and 4 in heat affected zone. Results of bending test...
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Predicting cutting power for band sawing process of pine and beech wood dried with the use of four different methods
PublikacjaWood drying is an important stage in the woodworking process. After drying, wood is subject to a re-sawing process, for which a high quality surface, low material loss, and high efficiency are often required. In this paper, forecasted values were presented of cutting power for the re-sawing process of pine and beech wood that were dried with four different methods. Forecasting of cutting power for an industrial band saw machine...
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A Circular Waveguide Dual-Mode Filter With Improved Out-of-Band Performance for Satellite Communication Systems
PublikacjaThis letter presents a novel design for a 3-D-printed circular waveguide dual-mode (CWDM) filter with a modified cavity shape. The modification leads to a wide spurious-free stopband, which is highly desirable for channel separation in waveguide contiguous output multiplexers (OMUXs) in satellite communication systems. The new resonant cavity design is a result of applying shape deformation to a basic circular cavity in order to...
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COMPOSITE FOOTBRIDGE - SYNERGY EFFECT IN COOPERATION BETWEEN UNIVERSITIES AND INDUSTRY
PublikacjaPaper presents conditions of science and industry cooperation in Poland (restrictions, barriers, good practice). A key role in initiation of collaboration between units has financial support. What is also important, it is much easier to create innovative solutions on the base of combining the potential of individuals. That is why many countries all over the world look for innovative solutions using budget funds to support grants...
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On the Equations of the Surface Elasticity Model Based on the Theory of Polymeric Brushes
PublikacjaMotivating by theory of polymers, in particular, by the models of polymeric brushes we present here the homogenized (continual) two-dimensional (2D) model of surface elasticity. A polymeric brush consists of an system of almost aligned rigid polymeric chains. The interaction between chain links are described through Stockmayer potential, which take into account also dipole-dipole interactions. The presented 2D model can be treated...
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Sensitivity analysis in design process of sandwich U-shaped composite footbridge
PublikacjaThe structure of the sandwich composite footbridge of a 14 metre span length and U-shaped cross-section was analysed. Sensitivity analysis was performed to support the design process of this innovative object. Linear discrete sensitivity analysis was performed by means of finite element method. The influence of vari-ation of several design variables i.e. thicknesses of inner and outer laminates on the mid-span deflection, as-sumed...
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In-situ and ex-situ resistance measurements of polypyrrole film using double-band electrode
PublikacjaMany in-situ techniques are performed in order to determine the resistance of conducting polymer film. However, the resistance measured in solution can be the combination of polymer resistance and that of other components, such as resistance of supporting electrolyte. Therefore, in this work, the influence of the solution on the resistance of polypyrrole (PPy) film has been studied. PPy film was electrchemically synthesized onto...
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Local Nusselt number evaluation in the case of jet impingement
PublikacjaJet impingement still is one of demanding cases regarding computational fluid dynamics, due to its highly turbulent behaviour, with occurrence of turbulent-laminar transition. Even recently developed methods exhibit some drawbacks – RANS based simulations lack accuracy, LES and DNS based ones require too much computational time. Hybrid methods also exist, but their development and validation is in progress. Nevertheless, CFD application...
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Electronically Excited States in Solution via a Smooth Dielectric Model Combined with Equation-of-Motion Coupled Cluster Theory
PublikacjaWe present a method for computing excitation energies for molecules in solvent, based on the combination of a minimal parameter implicit solvent model and the equation-of-motion coupled-cluster singles and doubles method (EOM-CCSD). In this method, the solvent medium is represented by a smoothly varying dielectric function, constructed directly from the quantum mechanical electronic density using only two tunable parameters. The...
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Speed management on local government managed roads – research, recommendations and guidelines
PublikacjaCommissioned by the National Road Safety Council Secretariat, the project “Guidelines for speed management on local government managed roads” studied car driver be haviour when subjected to selected speed management measures such a local speed restrictions, surveillance, traffic calming and restricted speed areas. In addition, analyses were conducted on the impact of selected me asures...
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Cross-Cultural Interactions between Expatriates and Local Managers in the Light of Positive Organizational Behaviour
PublikacjaThe main purpose of this article is to identify the ‘individual positive deviance’ presented by expatriates and local managers in their mutual cooperation. The theoretical basis for the publication is the discussion of the Positive Organizational Behaviour (POB) essence and the application of this approach in the area of expatriation. Attitudes, behaviour, working style and personality traits of employees of different nationalities...
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From Advice and Consultation to Local Co-governance. The Case of Advisory Councils in Polish Cities
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Non-stoichiometric magnetite as catalyst for the photocatalytic degradation of phenol and 2,6-dibromo-4-methylphenol – a new approach in water treatment
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Verification of the criteria for evaluation of water and frost resistance of asphalt concrete
PublikacjaThe paper presents the results of field investigation - condition survey of existing pavements and the results of laboratory tests on water and frost resistance of samples cored from the these pavements. The purpose of testing was to verify the criteria for evaluation of the resistance of asphalt concrete to the action of water and frost by way of comparing the results of field and laboratory tests, followed by evaluation of their...
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Structural Health Monitoring of Composite Shell Footbridge for Its Design Validation
PublikacjaThe paper presents the structural health monitoring system of the composite bridge for pedestrians and cyclists. The footbridge was designed and manufactured within the FOBRIDGE project. It is the first bridge in the world, which is classified as a consistent single element structural girder, made of sandwich shells, entirely produced in a single cycle. The developed structural health monitoring system, supported design process,...
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Pedestrian safety management using the risk-based approach
PublikacjaThe paper presents a concept of a multi-level pedestrian safety management system. Three management levels are distinguished: strategic, tactical and operational. The basis for the proposed approach to pedestrian safety management is a risk-based method. In the approach the elements of behavioural and systemic theories were used, allowing for the development of a formalised and repeatable procedure integrating the phases of risk...
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EMI mitigation of GaN power inverter leg by local shielding techniques
PublikacjaThis paper presents local shielding techniques applied to a half-bridge inverter leg with the aim to reduce the common mode (CM) current noise at converter’s DC input. The research study is conducted for 650V Enhancement mode Gallium Nitride (GaN) power transistor switches. Main contributors of parasitic capacitances referred to the inverter-leg middle point node are identified. Then, shielding solutions are proposed to reduce...
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Progress towards a unified approach to entanglement distribution
PublikacjaEntanglement distribution is key to the success of secure communication schemes based on quantum mechanics, and there is a strong need for an ultimate architecture able to overcome the limitations of recent proposals such as those based on entanglement percolation or quantum repeaters. In this work we provide a broad theoretical background for the development of such technologies. In particular, we investigate the question of whether...
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Experimental study on the effectiveness of polymer damper in damage reduction of temporary steel grandstand
PublikacjaA large number of accidents, involving collapses of temporary grandstands during different types of events, were observed in the past. If the synchronized movement of people is tuned with the natural frequency of the affected part of the structure, resonance might occur. It may lead to severe damages of grandstands, their collapse or panic among the spectators. The aim of the paper is to assess, through preliminary experimental...
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A novel dual-band rectifier circuit with enhanced bandwidth for RF energy harvesting applications
PublikacjaIn recent years, a rapid development of low-power sensor networks, enabling machine-to-machine communication in applications such as environmental monitoring, has been observed. Contemporary sensors are normally supplied by an external power source, typically in a form of a battery, which limits their lifespan and increases the maintenance costs. This problem can be addressed by harvesting and converting ambient RF energy into...
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A Novel Versatile Decoupling Structure and Expedited Inverse-Model-Based Re-Design Procedure for Compact Single-and Dual-Band MIMO Antennas
PublikacjaMultiple-input multiple-output (MIMO) antennas are considered to be the key components of fifth generation (5G) mobile communications. One of the challenges pertinent to the design of highly integrated MIMO structures is to minimize the mutual coupling among the antenna elements. The latter arises from two sources, the coupling in the free space and the coupling currents propagating on a ground plane. In this paper, an array of...
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THE INFLUENCE OF GESTALT THEORY ON ERNST CASSIRER’S PHENOMENOLOGY OF SYMBOLIC FORMS
PublikacjaIn the opinion of many scholars the notion of symbolic pregnancy is one of the key concepts in Ernst Cassirer’s philosophy of symbolic forms. Without a proper under-standing of its conceptual frame Cassirer’s philosophy lacks a consistent foundation. The notion symbolic pregnancy offers the mechanism of distinction of symbolic forms. The newest investigations (also in unpublished or less known, neglected writings of the philosopher)...
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Design of experiments approach for ultimate strength assessment of corroded stiffened plates
PublikacjaThe impact of corrosion degradation on the ultimate strength of stiffened plates subjected to compressive loading is investigated. The DoE technique is used considering different plate and column slenderness ratios and corrosion severity. The FE method, considering geometrical and material nonlinearities, is employed. A two-stage corrosion degradation model is adopted. Firstly, a uniform thickness loss is adopted to reflect the...
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Experimental tests and numerical simulations of full scale composite sandwich segment of a foot- and cycle- bridge
PublikacjaIn the paper experimental tests and numerical simulations of a full cross-section segment of ultimately designed foot-and cycle-bridge are presented. The experimental tests were conducted on element with length reduced to 3 m and unchanged (target) cross-section dimensions. The external skin of structure is GFRP laminate while internal core is PET foam. Several quasi-static tests were performed using hydraulic cylinder to generate...
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General Provisioning Strategy for Local Specialized Cloud Computing Environments
PublikacjaThe well-known management strategies in cloud computing based on SLA requirements are considered. A deterministic parallel provisioning algorithm has been prepared and used to show its behavior for three different requirements: load balancing, consolidation, and fault tolerance. The impact of these strategies on the total execution time of different sets of services is analyzed for randomly chosen sets of data. This makes it possible...
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Equivalent 4-node enhanced assumed strain and hybrid stress shell elements in 6-parameter theory
PublikacjaWe discuss the equivalence of semi-enhanced assumed strain (EAS) and semi-hybrid stress (SEM) shell finite elements. We use the general nonlinear 6-field shell theory with kinematics composed of generalized displacements composed of the translation field and the rotation field. Due to the presence of rotation tensor the elements have naturally six nodal engineering degrees of freedom. We propose interpolation for a strain field...
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Effect of polymer fibres reinforcement on selected properties of asphalt mixtures
PublikacjaThe paper presents selected results of the research program concerning fibre reinforced asphalt concrete. Aramid-polyalphaolefin fibres was used in this study. Selected properties responsible for low temperature cracking and resistance to permanent deformation are presented in this paper. Low temperature cracking susceptibility was evaluated with the results obtained from bending test of rectangular beams with constant rate of...
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The Impact of Ground Tire Rubber Oxidation with H2O2 and KMnO4 on the Structure and Performance of Flexible Polyurethane/Ground Tire Rubber Composite Foams
PublikacjaThe use of waste tires is a very critical issue, considering their environmental and economic implications. One of the simplest and the least harmful methods is conversion of tires into ground tire rubber (GTR), which can be introduced into different polymer matrices as a filler. However, these applications often require proper modifications to provide compatibility with the polymer matrix. In this study, we examined the impact...
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Influence of service ageing on polyester-reinforced polyvinyl chloride-coated fabrics reported through mathematical material models
PublikacjaIn this paper the coupled service (constructional tension) and environmental (sunlight, rainfalls, temperature variations) ageing influence on the polyester-reinforced polyvinyl chloride (PVC)-coated fabric VALMEX is studied. Two cases of the same fabric have been analyzed: one USED for 20 years on the real construction of the Forest Opera in Sopot (Poland), and one kept as a spare material (NOT USED). The following tests have...
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The use of a two-phase Monte Carlo material model to reflect the dispersion of asphalt concrete fracture parameters
PublikacjaThe work covers comprehensive laboratory tests of semi-circular bending (SCB) of asphalt concrete samples. The results of two test series, including four and 32 SCB specimens, indicate a substantial scatter of force–deflection (F-d) histories. The numerical analysis is aimed to reflect the maximum breaking load and fracture energy of the samples, pointing out their random character. The original simulation-based fictitious Monte...
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Modelling and FE-simulation of plastic ductile damage evolution in plates and shells
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Electrochemical behavior of a composite material containing 3D-structured diatom biosilica
Publikacja3D-structured diatom biosilica mixed with conducting carbon black was investigated as an active electrode material for lithium-ion batteries. Diatom biosilica was obtained by cultivation of the selected diatom species under laboratory conditions. Several instrumental techniques (XRD, FTIR, Raman, SEM-EDX, TGA) were used to characterize the physicochemical properties of applied biosilica. It was evidenced that the prepared new composite...
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Non-destructive inspection of ground anchors using guided wave propagation
PublikacjaThis paper deals with numerical and experimental investigations of specific problems of guided wave propagation in ground anchors. The research focuses on recognizing the phenomenon of the energy transfer between anchor components. Particular attention is paid to characteristic features of guided waves propagating in free and embedded parts of the tendon, at the interface between the tendon and the surrounding anchor body as well...
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Coupled nonlinear Schrödinger equations in optic fibers theory
PublikacjaIn this paper a detailed derivation and numerical solutions of CoupledNonlinear Schr¨odinger Equations for pulses of polarized electromagnetic wavesin cylindrical fibers has been reviewed. Our recent work has been compared withsome previous ones and the advantage of our new approach over other methods hasbeen assessed. The novelty of our approach lies is an attempt to proceed withoutloss of information within the frame of basic...
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Experimental and Numerical Investigation of Tensile and Flexural Behavior of Nanoclay Wood-Plastic Composite
PublikacjaIn this study, the effect of wood powder and nanoclay particle content on composites’ mechanical behavior made with polyethylene matrix has been investigated. The wood flour as a reinforcer made of wood powder was at levels of 30, 40, and 50 wt.%, and additional reinforcement with nanoclay at 0, 1, 3, and 5 wt.%. Furthermore, to make a composite matrix, high-density polyethylene was used at levels of 70, 60, and 50% by weight....
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Non-destructive Testing of Wooden Elements
PublikacjaExamining the condition of wooden elements is crucial from the perspective of proper structure performance. If the deterioration in the internal wood condition, which displays no symptoms visible from the outside, is detected, the further spread of the deterioration can be prevented. Test results often point to the necessity of conducting repairs and, renovations, replacing the structure of wooden beams, or even substituting a...
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Dual-band Millimetre Wave MIMO Antenna with Reduced Mutual Coupling Based on Optimized Parasitic Structure and Ground Modification
PublikacjaIn this study, a high-isolation dual-band (28/38 GHz) multiple-input–multiple-output (MIMO) antenna for 5G millimeter-wave applications is presented. The antenna consists of two interconnected patches. The primary patch is connected to the inset feed, while the secondary patch is arc-shaped and positioned over the main patch, opposite to the feed. Both patches function in the lower 28 GHz band, while the primary patch is accountable...
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A strategy for GPS data processing in a precise local network during high solar activity
PublikacjaThis paper presents the analyses connected with reduction of errors from ionospheric refraction using GPS data from local satellite networks. This is particularly essential during rising solar activity. The Bernese GPS Software v. 4.2 was used, as an analytical tool. The test data included measurements from a geodynamic network SUDETES situated in the Sudety Mountains across the border between the Czech Republic and Poland. A local...
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Static and dynamic concrete calculations: Breakable aggregates in DEM model
PublikacjaThe paper deals with the calculations of a 3-point bending beam under static and dynamic loads. The real microstructure was obtained from laboratory tests using micro-tomography images. The quasi-static results were compared directly with experimental data at both macro and micro levels. Subsequently, higher strain rates were applied to investigate dynamic effects. The study focused on the influence of dynamic loading on the macroscopic...
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Comparative Analysis of Regular Grid Based Algorithms in the Design of Graphical Control Panels
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Subjective Perception of the Background Color and Layout in the Design of Typical Graphical Control Panels
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Modern GFRP Composite Footbridges
PublikacjaApplication of GFRP composites in civil engineering is still not large but already noticeable. Advantages of this material, such as: low volume weight, relatively high stiffness and strength, well fatigue resistance, easiness in shaping, high material damping and high environmental resistance, make it attractive for bridge and in particular foot-bridge designers. It is estimated that nowadays in the world there are realized hundreds...
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Automated Valuation Model based on fuzzy and rough set theory for real estate market with insufficient source data
PublikacjaObjective monitoring of the real estate value is a requirement to maintain balance, increase security and minimize the risk of a crisis in the financial and economic sector of every country. The valuation of real estate is usually considered from two points of view, i.e. individual valuation and mass appraisal. It is commonly believed that Automated Valuation Models (AVM) should be devoted to mass appraisal, which requires a large...
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An Approach to Mean Path Loss Model Estimation for Off-Body Channels
PublikacjaThis paper presents an approach to estimation of the mean path loss model parameters in off-body Body Area Networks channels. In this approach, the path loss exponent is constrained to a value obtained for the line-of-sight (LoS) propagation in the co-polarised channel, considering a generalised static scenario. The comparison of the goodness of fit between the proposed approach and other approaches, for a set of measurements obtained...
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Machine learning-based prediction of preplaced aggregate concrete characteristics
PublikacjaPreplaced-Aggregate Concrete (PAC) is a type of preplaced concrete where coarse aggregate is placed in the mold and a Portland cement-sand grout with admixtures is injected to fill the voids. Due to the complex nature of PAC, many studies were conducted to determine the effects of admixtures and the compressive and tensile strengths of PAC. Considering that a prediction tool is needed to estimate the compressive and tensile...
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Machine learning-based prediction of preplaced aggregate concrete characteristics
PublikacjaPreplaced-Aggregate Concrete (PAC) is a type of preplaced concrete where coarse aggregate is placed in the mold and a Portland cement-sand grout with admixtures is injected to fill the voids. Due to the complex nature of PAC, many studies were conducted to determine the effects of admixtures and the compressive and tensile strengths of PAC. Considering that a prediction tool is needed to estimate the compressive and tensile strengths...
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Discrete identification of continuous non-linear and non-stationary dynamical systems that is insensitive to noise correlation and measurement outliers
PublikacjaThe paper uses specific parameter estimation methods to identify the coefficients of continuous-time models represented by linear and non-linear ordinary differential equations. The necessary approximation of such systems in discrete time in the form of utility models is achieved by the use of properly tuned `integrating filters' of the FIR type. The resulting discrete-time descriptions retain the original continuous parameterization...