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Search results for: MEAN ERRORS OF DISPLACEMENTS
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Weak Stability of Centred Quadratic Stochastic Operators
PublicationWe consider the weak convergence of iterates of so-called centred quadratic stochastic operators. These iterations allow us to study the discrete time evolution of probability distributions of vector-valued traits in populations of inbreeding or hermaphroditic species, whenever the offspring’s trait is equal to an additively perturbed arithmetic mean of the parents’ traits. It is shown that for the existence of a weak limit, it...
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High-temperature kinetics study of 430L steel powder oxidized in air at 600–850 °C
PublicationThe 430L stainless steel powder with a mean particle size of 95 μm was studied to determine its high-temperature oxidation properties. Continuous thermogravimetric measurements were carried out for 100 h in air at temperatures in the range of 600–850 °C. Even though a considerable amount of Cr (up to ˜5 wt.% Cr) inside the grains was depleted – especially inside small grains – no breakaway oxidation was observed. This indicates...
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Wideband Off-Body Channel Characteristics with Dynamic User
PublicationThis paper presents the preliminary results of a dynamic off-body channel characterisation study, based on wideband measurements at 5.8 GHz in an indoor environment. The Channel Impulse Response (CIR) was measured for a scenario with the user approaching and departing from the off-body antenna. A CIR deconvolution procedure was performed jointly in two polarisations, and the received signal power, Cross-Polarisation Discrimination...
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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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Proportional-Derivative and Model-Based Controllers for Control of a Variable Mass Manipulator
PublicationIn the paper, numerical analysis of dynamics of a variable mass manipulator is presented. A revolute joints composed manipulator is considered. Payload of the gripper is considered as the only element characterized by unknown value of its mass (variable between subsequent operations). As in other cases of the revolute joints composed manipulators, its behaviour dependents significantly on the pose of the manipulator. When the manipulator...
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Bi-GRU-APSO: Bi-Directional Gated Recurrent Unit with Adaptive Particle Swarm Optimization Algorithm for Sales Forecasting in Multi-Channel Retail
PublicationIn the present scenario, retail sales forecasting has a great significance in E-commerce companies. The precise retail sales forecasting enhances the business decision making, storage management, and product sales. Inaccurate retail sales forecasting can decrease customer satisfaction, inventory shortages, product backlog, and unsatisfied customer demands. In order to obtain a better retail sales forecasting, deep learning models...
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The correlation of fractal dimension to fracture surface slope for fatigue crack initiation analysis under bending-torsion loading in high-strength steels
PublicationIn this study, the fractal dimension of fatigue fracture surfaces is investigated in order to find an alternative failure loading indicator. Some of many metrological factors are generalized by reducing the fracture surface structure to one factor and develop an entire fracture surface procedure by analyzing the impact of surface slope and calculation resolution. Three notched geometries are studied under cyclic bending-torsion:...
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Computational Complexity and Its Influence on Predictive Capabilities of Machine Learning Models for Concrete Mix Design
PublicationThe design of concrete mixtures is crucial in concrete technology, aiming to produce concrete that meets specific quality and performance criteria. Modern standards require not only strength but also eco-friendliness and production efficiency. Based on the Three Equation Method, conventional mix design methods involve analytical and laboratory procedures but are insufficient for contemporary concrete technology, leading to overengineering...
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Effective Air Quality Prediction Using Reinforced Swarm Optimization and Bi-Directional Gated Recurrent Unit
PublicationIn the present scenario, air quality prediction (AQP) is a complex task due to high variability, volatility, and dynamic nature in space and time of particulates and pollutants. Recently, several nations have had poor air quality due to the high emission of particulate matter (PM2.5) that affects human health conditions, especially in urban areas. In this research, a new optimization-based regression model was implemented for effective...
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Self-assessment of competencies of students and graduates participating in didactic projects – Case study
PublicationAim/purpose: the aim of this article is to examine the opinions of students and graduates of the faculty of economics of a technical university as regards their selfassessment of their preparation for entering the modern labour market. All the respondents participated during their studies in didactic projects aimed at improving their competencies taking into account the expectations of potential employers. Design/methodology/approach:...
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Measured and predicted freeze-thaw days frequencies in climate change conditions in central Poland
PublicationThe rate of progression of geomorphological phenomena is greatly influenced by freeze-thaw processes. In the face of air temperature increasing over the past few decades, a question of the future impact of these processes arises, notably in the temperate and cold climate zones. Using the mean, maximum and minimum daily air temperature data in the period 1951–2018 obtained from three weather stations located in the vicinity of Jeziorsko...
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Comparative study on total nitrogen prediction in wastewater treatment 1 plant and effect of various feature selection methods on machine learning algorithms performance
PublicationWastewater characteristics prediction in wastewater treatment plants (WWTPs) is valuable and can reduce the number of sampling, energy, and cost. Feature Selection (FS) methods are used in the pre-processing section for enhancing the model performance. This study aims to evaluate the effect of seven different FS methods (filter, wrapper, and embedded methods) on enhancing the prediction accuracy for total nitrogen (TN) in the WWTP...
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A Comparability of Renal Length and Volume Measurements in MRI and Ultrasound in Children
PublicationIntroduction: Despite the significant increase in use of magnetic resonance imaging (MRI) in children, there is still a lack of normal reference values of renal size in this method and reference values are being interpolated from the ultrasound (US) studies. The study provides comparative analysis of agreement in renal length and volume measurements between MRI and ultrasound. Materials and Methods: Ninety-three children with a...
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ARIMA vs LSTM on NASDAQ stock exchange data
PublicationThis study compares the results of two completely different models: statistical one (ARIMA) and deep learning one (LSTM) based on a chosen set of NASDAQ data. Both models are used to predict daily or monthly average prices of chosen companies listed on the NASDAQ stock exchange. Research shows which model performs better in terms of the chosen input data, parameters and number of features. The chosen models were compared using...
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Structured deformation of granular material in the state of active earth pressure
PublicationThe paper focuses on the ability of granular materials to undergo structured deformation by analysing the data from the retaining wall model tests and discrete element simulations. The structured deformation means the movement of a granular material which produces a stable, regular pattern of multiple shear bands. The paper's primary purpose is to study this kind of deformation for the selected data representing the state of active...
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The process of identification of the track's geometrical layout and the alignment project based on the of satellite measurements
PublicationIn the paper a methodology of restoring of railway track’s geometrical shape in a horizontal plane on the base of conducted mobile satellite surveying was presented. The authors proposed a calculating algorithm for designing the track sections placed in horizontal arcs. In the algorithm an analytical methodology with mathematical formulas is applied. The procedure has an universal character, i.e. provides the possibility of varying...
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Satellite inventory of tram track geometrical layout
PublicationIn the paper a methodology of restoring of railway track’s geometrical shape in a horizontal plane on the base of conducted mobile satellite surveying was presented. The authors proposed a calculating algorithm for designing the track sections placed in horizontal arcs. In the algorithm an analytical methodology with mathematical formulas is applied. The procedure has an universal character, i.e. provides the possibility of varying...
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Experimental study on polymer mass used to repair damaged structures
PublicationA new method of repairing damaged structures by injecting the cracks with specially designed polymer mass (flexible two-component grout based on polyurethane resin) has been recently proposed. The technique is mainly dedicated to damaged masonries, especially historical structures where minimum intervention is permitted. The cracks are filled with the special injection, forming the flexible joints bonding the disrupted structural...
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The influence of the place of residence on the behavior and transport preferences of the inhabitants of the agglomeration
PublicationTransport behaviors and preferences have an impact on modal split, which is why they should form the basis for shaping the public transport offer. Achieving the goals of sustainable mobility requires taking into account differences in transport behavior and preferences characterizing residents from different areas of the agglomeration. Analyzing differences in behaviors and preferences, the possibilities and limitations resulting...
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Thermal failure of a second rotor stage in heavy duty gas turbine
PublicationThe impulse mode of operation and the supply of various types of fuels causes frequent failures even in the heavy duty gas turbines. The paper presents the ravages of second rotor stage failure in a gas turbine. The excessive thermal elongation rise caused by fuel change was indicated as the main cause. We applied nonlinear numerical analysis, preceded by thermodynamic calculations of the turbine and visual inspection of the effects...
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Estimation of nonstructural stiffness in instrumented steel frames
PublicationLateral stiffness of nonstructural components may significantly influence the initial stiffness of the entire structure and consequently alter its dynamic characteristics. While methods for simulating structural members are well-established, approaches for modeling nonstructural components that also participate in seismic response are notably less developed. In this paper a simplified, physically-intuitive approach for estimating...
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Using Minimum Actuators to Control Shape and Stress of a Double Layer Spherical Model Under Gravity and Lateral Loadings
PublicationSpherical domes are picturesque structures built in developed countries to attract tourists. Due to horizontal and vertical overloading, the structures’ attractive shapes may be disturbed, and some members' stress may exceed the elastic level. In this paper, the shape and stress of a deformed double-layer spherical numerical model due to simultaneous lateral and vertical loadings are controlled, meanwhile, the number of actuators...
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Static Shape and Stress Control of Trusses with Optimum Time, Actuators and Actuation
PublicationTraditional shape and stress control of structures use many actuators and require enormous time to find reasonable solutions that need designers to input specific target displacement and stress. This study employs a linear technique to static shape and stress control of pin-jointed assemblies as a theoretical advancement to prior works and provides a comparative analysis against previously established works. The study evaluates...
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Przyczyny uszkodzeń i sposób naprawy posadzki ze styrobetonu
PublicationW artykule opisano uszkodzenia, badania i sposób naprawy posadzki wykonanej na istniejącym stropie żelbetowym o powierzchni ok. 1050 m2 i podłożu ze styrobetonu. W posadzce stwierdzono znaczne uszkodzenia w postaci zarysowań, odspojeń i nierówności. W celu określenia ich przyczyn wykonano badania in situ oraz badania laboratoryjne. Stwierdzono, że przyczyną powstania uszkodzeń są błędy wykonawcze. Wykonano próbną naprawę uszkodzeń...
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Detection of vehicles stopping in restricted zones in video from surveillance cameras
PublicationAn algorithm for detection of vehicles that stop in restricted areas, e.g. excluded by traffic rules, is proposed. Classic approaches based on object tracking are inefficient in high traffic scenes because of tracking errors caused by frequent object merging and splitting. The proposed algorithm uses the background subtraction results for detection of moving objects, then pixels belonging to moving objects are tested for stability....
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The Effect of Flexible Pavement Mechanics on the Accuracy of Axle Load Sensors in Vehicle Weigh-in-Motion Systems
PublicationWeigh-in-Motion systems are tools to prevent road pavements from the adverse phenomena of vehicle overloading. However, the effectiveness of these systems can be significantly increased by improving weighing accuracy, which is now insufficient for direct enforcement of overloaded vehicles. Field tests show that the accuracy of Weigh-in-Motion axle load sensors installed in the flexible (asphalt) pavements depends on pavement temperature...
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Measurements of fundamental properties of homogeneous tissue phantoms
PublicationWe present the optical measurement techniques used in human skin phantom studies. Their accuracy and the sources of errors in microscopic parameters’ estimation of the produced phantoms are described. We have produced optical phantoms for the purpose of simulating human skin tissue at the wavelength of 930 nm. Optical coherence tomography was used to measure the thickness and surface roughness and to detect the internal inhomogeneities....
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Computationally Effcient Solution of a 2D Diffusive Wave Equation Used for Flood Inundation Problems
PublicationThis 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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Space-Time Conservation Method applied to numerical solution of water hammer equations
PublicationArtykuł poświęcony jest metodzie czasoprzestrzennych objętości skończonych (STC) zastosowanej do przypadku uderzenia hydraulicznego w stalowym przewodzie pracującym pod ciśnieniem. Metoda STC ze względu na swoje własności numeryczne - m.in. wysoką dokładność - może być interesującą alternatywą dla tradycyjnych metod numerycznych, szczególnie w przypadku, gdy efekty numeryczne mają bardzo silny wpływ na rozwiązanie, tym samym utrudniając...
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Solution of the dike-break problem using finite volume method and splitting technique
PublicationIn the paper the finite volume method (FVM) is presented for the solution of two-dimensional shallow water equations. These equations are frequently used to simulate the dam-break and dike-break induced flows. The applied numerical algorithm of FVM is based on the wave-propagation algorithm which ensures a stable solution and simultaneously minimizes the numerical errors. The dimensional decomposition according to the coordinate...
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Hybrid Technique Combining the FDTD Method and Its Convolution Formulation Based on the Discrete Green's Function
PublicationIn this letter, a technique combining the finite-difference time-domain (FDTD) method and its formulation based on the discrete Green's function (DGF) is presented. The hybrid method is applicable to inhomogeneous dielectric structures that are mutually coupled with wire antennas. The method employs the surface equivalence theorem in the discrete domain to separate the problem into a dielectric domain simulated using the FDTD method...
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Validation of Interpolation Algorithms for Multiscale UV-VIS Imaging Using UAV Spectrometer
PublicationIn this study, we present a comparison of popular methods for the interpolation of irregular spatial data in order to determine the applicability of each algorithm for hyperspectral reflectance estimation. The algorithms were benchmarked against a very high-resolution orthoimage from an RGB camera and medium-resolution satellite imagery from Sentinel-2A. We tested five interpolation algorithms: Triangulated Irregular Network (TIN),...
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Evaluation of the prediction ability of air pollutants based on the electronic nose responses
PublicationElectronic noses are able to perform on-line measurements of the toxic volatile compounds in air. Due to their low cost and compact size they can be placed in the areas exposed to pollution, outside the laboratory. Those advantages, on the other side, force the need for development of the reliable sensors data analysis procedures. One of the most important issues connected with electronic noses is the lack of stability of the gas...
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Methodology for the Correction of the Spatial Orientation Angles of the Unmanned Aerial Vehicle Using Real Time GNSS, a Shoreline Image and an Electronic Navigational Chart
PublicationUndoubtedly, Low-Altitude Unmanned Aerial Vehicles (UAVs) are becoming more common in marine applications. Equipped with a Global Navigation Satellite System (GNSS) Real-Time Kinematic (RTK) receiver for highly accurate positioning, they perform camera and Light Detection and Ranging (LiDAR) measurements. Unfortunately, these measurements may still be subject to large errors-mainly due to the inaccuracy of measurement of the optical...
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A New Approach to Capacitive Sensor Measurements Based on a Microcontroller and a Three-Gate Stable RC Oscillator
PublicationA complete smart capacitive sensor solution basedA complete smart capacitive sensor solution based on a microcontroller was developed. This approach includes the development of both the hardware and software. The hardware part comprises an 8-bit microcontroller equipped with two timers/counters and a three-gate stable RC relaxation oscillator. The software part handles system configuration, measurement control, communication control,...
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Comprehensive dimension scaling of multi-band antennas for operating frequencies and substrate parameters
PublicationIn this paper, low-cost and comprehensive redesign of multi-band antennas with respect to the operating frequencies and material parameters of the substrate is presented. Our approach exploits an inverse surrogate model identified based on a set of reference designs optimized at the level of coarse-discretization EM simulations of the antenna at hand. An iterative correction procedure is also implemented to account for the initial...
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Safety at railway level crossings and Vision Zero
PublicationIn this work, safety analysis at the railway level crossings is presented using advanced mathematical modelling. Resistivity of track subgrade panels is taken into account. The analysis does not refer to the assessment of the current regulations. Specific cases of generalized dynamic system are considered by introducing operations S=Δ, S=P defined in space C(N) of real sequences. In this model, generalized discrete exponential...
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Accurate PPCC-Based DoA Estimation Using Multiple Calibration Planes for WSN Nodes Equipped with ESPAR Antennas
PublicationIn this paper, we have introduced a new direction-of-arrival (DoA) estimation method, which relies on received signal strength (RSS) values measured at the output port of electronically steerable parasitic array radiator (ESPAR) antenna and uses the power pattern cross-correlation (PPCC) estimator. In the method, we have successfully incorporated measurements of ESPAR antenna's radiation patterns performed at multiple calibration...
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Accuracy of the Discrete Green's Function Formulation of the FDTD Method
PublicationThis paper reports an evaluation of the accuracy of the discrete Greens function (DGF) formulation of the finite-difference time-domain (FDTD) method. Recently, the closed-form expression for the DGF and its efficient numerical implementation were presented, which facilitates applications of the DGF in FDTD simulations of radiation and scattering problems. So far, the accuracy of the DGF formulation of the FDTD method has been...
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RMS-based damage detection in reinforced concrete beams: numerical simulations
PublicationImage-based damage detection methods using guided waves are well known and widely applied approaches in structural diagnostics. They are usually utilized in detection of surface damages or defects of plate-like structures. The article presents results of the study of applicability of imaging wave-based methods in detection in miniscule internal damage in the form of debonding. The investigations were carried out on numerical models...
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Module architecture as alternative approach to traditional construction processes
PublicationModule architecture today is a special type of building construction process that combines repetitive design, low-cost production based on prefabricated elements and fast erection. Module does not mean the same as modular. In general, module architecture today refers to the design of any system composed of separate components, manufactured before in factory, that can be connected together at the building site much faster than normally....
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Study of the atomic structure and morphology of the Pt3Co nanocatalyst
PublicationThe local structure and chemical disorder of a commercially available Pt3Co nanocatalyst supported on high surface area carbon were investigated. High-quality XAFS spectra were collected at the ELETTRA synchrotron XAFS 11.1 beamline. XAFS spectra analysis have been performed accounting for the reduction of the coordination number and degeneracy of three-body configurations, resulting from transmission electron microscopy (TEM)...
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On ''cheap smoothing'' opportunities in identification of time-varying systems
PublicationIn certain applications of nonstationary system identification the model-based decisions can be postponed, i.e. executed with a delay. This allows one to incorporate into the identification process not only the currently available information, but also a number of ''future'' data points. The resulting estimation schemes, which involve smoothing, are not causal. Despite the possible performance improvements, the existing smoothing...
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System Loss Model for Body-to-Body Networks in Indoor and Outdoor Environments
PublicationA system loss model for body-to-body networks in indoor and outdoor environments is proposed in this paper, based on measurements taken at 2.45 GHz. The influence of the type of environment, antenna visibility and user mobility on model parameters has been investigated. A significant impact of mutual antennas’ placement and their visibility is shown. The proposed model fits well to empirical data, with the average root mean square...
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Comparative analysis of numerical with optical soliton solutions of stochastic Gross–Pitaevskii equation in dispersive media
PublicationThis article deals with the stochastic Gross–Pitaevskii equation (SGPE) perturbed with multiplicative time noise. The numerical solutions of the governing model are carried out with the proposed stochastic non-standard finite difference (SNSFD) scheme. The stability of the scheme is proved by using the Von-Neumann criteria and the consistency is shown in the mean square sense. To seek exact solutions, we applied the Sardar subequation...
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Turmeric nanofiber-encapsulated natural product formulation act as a phytogenic feed additive—A study in broilers on growth performance, biochemical indices of blood, and E. coli in cecum
PublicationA phytogenic feed additive (PFA) formulation was prepared with bioactive molecules—curcuminoids, gingerol, and carvacrol by encapsulating in nanofiber isolated from turmeric spent (turmeric nanofiber, TNF). This formulation was completely characterized by scanning electron microscope, ultra performance liquid chromatography, and gas chromatography and evaluated for its efficacy. PFA-encapsulated TNF (PFA@TNF) considerably increased...
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Selected Aspects of Pavement Texture Influence on Tire Rolling Resistance
PublicationTire rolling resistance has a significant influence on fuel consumption in cars and trucks and on CO2 emissions. Rolling resistance depends on the tire construction, pavement texture and stiffness, as well as environmental and traffic conditions. This article presents a pilot study on the impact of pavement texture on the rolling resistance of passenger car tires. Reasons why Mean Profile Depth is not a good descriptor of pavement...
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Fiasko projektu inwestycyjnego spowodowane błędami rozpoznania stanu technicznego obiektu i wykonanej dokumentacji projektowej
PublicationRealizacja przedsięwzięć inwestycyjnych w istniejących obiektach budowlanych związana jest z koniecznością wykonania rzetelnej weryfikacji ich aktualnego stanu technicznego, użytych materiałów, wprowadzonych zmian oraz uszkodzeń powstałych w czasie eksploatacji. Pozyskane informacje są podstawą do podejmowania decyzji zarówno technicznych, jak i ekonomicznych związanych z planami inwestycyjnymi. Błędy popełnione przez inżynierów...
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Structural properties of hypothetical CeBa2Cu3O7 compound from LSDA+DMFT calculations
PublicationThe hypothetical stoichiometric CeBa2Cu3O7 (Ce123) compound, which has not been synthesized as a single phase yet, was studied by the density functional theory (DFT). We utilized a method which merges the local spin density approximation (LSDA) with the dynamical mean-field theory (DMFT) to account for the electronic correlations. The LSDA+DMFT calculations were performed in the high-temperature range. The particular emphasis was...
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Vibration surveillance for efficient milling of flexible details fixed in adjustable stiffness holder
PublicationThe paper presents the results of research related to the possibility of using an intelligent workpiece holder with adjustable stiffness, during end milling process. Machining a one side supported flexible workpiece will be performed with constant spindle speed and feed speed. In order to avoid hazardous vibration, stiffness of the especially designed spring (mounted in a workpiece holder) will be modified off-line. In order to...