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Wyniki wyszukiwania dla: abyssal engineering
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Fast multi-objective design optimization of microwave and antenna structures using data-driven surrogates and domain segmentation
PublikacjaPurpose Strategies and algorithms for expedited design optimization of microwave and antenna structures in multi-objective setup are investigated. Design/methodology/approach Formulation of the multi-objective design problem oriented towards execution of the population-based metaheuristic algorithm within the segmented search space is investigated. Described algorithmic framework exploit variable fidelity modeling, physics- and...
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Rapid multi-objective optimization of antennas using nested kriging surrogates and single-fidelity EM simulation models
PublikacjaEver increasing performance requirements make the design of contemporary antenna systems a complex and multi-stage process. One of the challenges, pertinent to the emerging application areas but also some of the recent trends (miniaturization, demands for multi-functionality, etc.), is the necessity of handling several performance figures such as impedance matching, gain, or axial ratio, often over multiple frequency bands. The...
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Expedited antenna optimization with numerical derivatives and gradient change tracking
PublikacjaDesign automation has been playing an increasing role in the development of novel antenna structures for various applications. One of its aspects is electromagnetic (EM)-driven design closure, typically applied upon establishing the antenna topology, and aiming at adjustment of geometry parameters to boost the performance figures as much as possible. Parametric optimization is often realized using local methods given usually reasonable...
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Random field modelling of mechanical behaviour of corroded thin steel plate specimens
PublikacjaThe objective of this work is to explore the possibility of corrosion degradation modelling of thin steel plate specimens with the use of random field approach. The mechanical properties are obtained via the nonlinear Finite Element Analysis with the use of an explicit dynamic solver. The fully nonlinear material model is adopted to obtain the proper stress-strain response. Sensitivity analysis considering the main statistical...
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Application of shifted Chebyshev polynomial-based Rayleigh–Ritz method and Navier’s technique for vibration analysis of a functionally graded porous beam embedded in Kerr foundation
PublikacjaPresent study is dealt with the applicability of shifted Chebyshev polynomial based Rayleigh-Ritz method and Navier’s technique on free vibration of Functionally Graded (FG) beam with uniformly distributed porosity along the thickness of the beam. The material properties such as Young’s modulus, mass density, and Poisson’s ratio are also considered to vary along the thickness of the FG beam as per the power-law exponent model....
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Validation study on a new semi-empirical method for the prediction of added resistance in waves of arbitrary heading in analyzing ship speed trial results
PublikacjaThis paper describes an open and extensive validation study carried out by the Specialist Committee on Ships in Operation at Sea (SOS) of the International Towing Tank Conference (ITTC) on the newly developed SHOPERA-NTUA-NTU-MARIC (SNNM) wave-added resistance prediction method. The SNNM method aims at a simple, fast and transparent determination of the added resistance in regular waves of arbitrary encounter directions, even when...
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Indoor accelerated controlled corrosion degradation test of small- and large-scale specimens
PublikacjaThe work presented here is a part of a long-term project analysing the structural behaviour of ageing marine structures. An accelerated corrosion degradation set-up was developed to reproduce corroded marine structural specimens of different degrees of degradation, controlling various natural factors, i.e., temperature, oxygen content, salinity, and flow velocity. The nine stiffened plates of 1.2 m length and 30 small scale specimens...
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Incremental dynamic analysis and fragility assessment of buildings founded on different soil types experiencing structural pounding during earthquakes
PublikacjaThe effect of the soil type on buildings experiencing pounding during earthquakes is investigated in this study using the incremental dynamic analysis and fragility assessment methods. Three 3-D structures with different number of storeys (4, 6 and 8) were considered in this study. Three pounding scenarios between these three buildings were taken into account, i.e. pounding between 4-storey and 6-storey buildings, between 4-storey...
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Computer Support of Analysis of Optical Spectra Measurements
PublikacjaThe verification of measurement errors has a big impact on the assessment of the accuracy of conducted measurements and obtained results. In many cases, computer simulation results are compared with measurement results in order to evaluate measurement errors. The purpose of our research was to check the accuracy of measurements made with a Fabry–Perot interferometer working in the transmission mode. In the measurement setup, a...
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Temperature Fiber-Optic Sensor with ZnO ALD Coating
PublikacjaThis study presents a microsphere-based fiber-optic sensor with a ZnO Atomic Layer Deposition (ALD) coating thickness of 100 nm for temperature measurements. Metrological properties of the sensor were investigated over the temperature range of 100 °C to 300 °C, with a 10 °C step. An interferometric signal is used to control whether the microstructure is whole. Spectrum shift of a reflected signal is used to ascertain changes in...
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Impact of thermal loading into the structural performance of ships: A review
PublikacjaThe presented study reviews the recent advances done regarding the impact of thermal loading on the structural performance of ships. Firstly, the studies related to the mechanical and thermal properties of typical materials used in shipbuilding are outlined. Secondly, a brief introduction to the heat transfer analysis, Finite Element modelling and thermal stresses is provided. Finally, the review of papers dealing with the structural...
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Control of the bridge span vibration with high coefficient passive damper. Theoretical consideration and application
PublikacjaThe research was carried out due to the problem of vibration on the lively pedestrian drawbridge across the Motlawa River in the city of Gdansk. In the design stage, the main span of the footbridge showed unfavorable dynamic properties, which may create a comfort problem for pedestrians. The first vertical bending eigenfrequency was recognized as 1.64 Hz. The original design of the footbridge was equipped with a driving cylinder...
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A framework for accelerated optimization of antennas using design database and initial parameter set estimation
PublikacjaThe purpose of this paper is to exploit a database of pre-existing designs to accelerate parametric optimization of antenna structures is investigated. Design/methodology/approach The usefulness of pre-existing designs for rapid design of antennas is investigated. The proposed approach exploits the database existing antenna base designs to determine a good starting point for structure optimization and its response sensitivities....
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Experimental and computational study on mechanical behaviour of carpentry corner log joints
PublikacjaThis work concerns experimental and numerical research on carpentry joints used in historic wooden buildings in southeastern Poland and western Ukraine. These structures are mainly sacred buildings, and the types of corner log joints characteristic of this region are primarily saddle-notch and dovetail joints; thus, these two types of joints were analysed in this study. The modelling of historic timber structures is a complex...
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Implementation of Non-Probabilistic Methods for Stability Analysis of Nonlocal Beam with Structural Uncertainties
PublikacjaIn this study, a non-probabilistic approach based Navier’s Method (NM) and Galerkin Weighted Residual Method (GWRM) in term of double parametric form has been proposed to investigate the buckling behavior of Euler-Bernoulli nonlocal beam under the framework of the Eringen's nonlocal elasticity theory, considering the structural parameters as imprecise or uncertain. The uncertainties in Young’s modulus and diameter of the beam are...
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Experimental study on the selected aspects of bow thruster generated flow field at ship zero-speed conditions
PublikacjaThe paper presents the results of experimental study on the interaction between the bow thrusters understood as the flow field changes generated by bow tunnel thruster in deep water conditions operated as a single and twin units. The research was limited to zero-speed case for the ship dead in the water. The influence of the hull form and jet spread between the neighbouring thrusters for several combinations of the applied bow...
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An enhanced method in predicting tensile behaviour of corroded thick steel plate specimens by using random field approach
PublikacjaThe present work investigates the possibility of using random field techniques in modelling the mechanical behaviour of corroded thick steel plate specimens. The nonlinear Finite Element method, employing the explicit dynamic solver, is used to analyse the mechanical properties of typical specimens. A material model considering full nonlinearity is used to evaluate the stress-strain response. The influence of major governing parameters...
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Ship weather routing optimization with dynamic constraints based on reliable synchronous roll prediction
PublikacjaShip routing process taking into account weather conditions is a constrained multi-objective optimization problem and it should consider various optimization criteria and constraints. Formulation of a stability-related, dynamic route optimization constraint is presented in this paper. One of the key objectives of a cross ocean sailing is finding a compromise between ship safety and economics of operation. This compromise should...
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On ship roll resonance frequency
PublikacjaThe paper deals with the problem of modeling of rolling motion under a variety of excitation parameters. Special emphasis is put on the analysis and prediction of the frequency of the resonant mode of rolling, since it is often an essential issue in terms of motion of a ship related to her safety against capsizing or excessive amplitudes of roll. The research is performed for both free rolling and excited rolling and it is based...
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Estimation of nonstructural stiffness in instrumented steel frames
PublikacjaLateral 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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Towards evaluation of the Second Generation Intact Stability Criteria - examination of a fishing vessel vulnerability to surf-riding, based on historical capsizing
PublikacjaThe Second Generation Intact Stability Criteria (SGISC) are the latest achievements in the field of intact ship stability assessment. The criteria are the result of massive international cooperative efforts and extensive research that lasted more than 15 years. Even though they are based on a solid scientific foundation, the trial period has commenced to collect user experience and further validation. One of possible approaches...
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Determination of the dynamic critical maneuvering area in an encounter between two vessels: Operation with negligible environmental disruption
PublikacjaThis paper introduces the concept of Collision Avoidance Dynamic Critical Area (CADCA) for onboard Decision Support Systems (DSS). The indicator proposed is derived via identification of a minimum required maneuvering zone in an encounter between two vessels. The CADCA model accounts for ship maneuvering dynamics and associated hydrodynamic actions emerging from different rudder angles and forward speed effects. The method presented...
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Corrosion degradation monitoring of ship stiffened plates using guided wave phase velocity and constrained convex optimization method
PublikacjaThe study presents an experimental investigation on the corrosion degradation level assessment using nondestructive wave-based methods. The degradation level of ship structural elements has been assessed in two different ways. The first one is based on the spectral decomposition and zero-crossing incorporated reconstruction of the dispersion curve approach of the antisymmetric Lamb wave mode and the best matching of the theoretical...
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Uncertainty quantification of modal parameter estimates obtained from subspace identification: An experimental validation on a laboratory test of a large-scale wind turbine blade
PublikacjaThe uncertainty afflicting modal parameter estimates stems from e.g., the finite data length, unknown, or partly measured inputs and the choice of the identification algorithm. Quantification of the related errors with the statistical Delta method is a recent tool, useful in many modern modal analysis applications e.g., damage diagnosis, reliability analysis, model calibration. In this paper, the Delta method-based uncertainty...
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Automatic classification and mapping of the seabed using airborne LiDAR bathymetry
PublikacjaShallow coastal areas are among the most inhabited areas and are valuable for biodiversity, recreation and the economy. Due to climate change and sea level rise, sustainable management of coastal areas involves extensive exploration, monitoring, and protection. Current high-resolution remote sensing methods for monitoring these areas include bathymetric LiDAR. Therefore, this study presents a novel methodological approach to assess...
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Identification of the Vistula Mounting tower model using measured modal data
PublikacjaW pracy przedstawiono problem identyfikacji pięcioparametrowego modelu zabytkowej wieży twierdzy Wisłoujście. Poszukiwane parametry wyznaczono jako rozwiązanie problemu minimalizacji błędu średniokwadratowego pomierzonych dwóch pierwszych częstości i pierwszej postaci drgań własnych. Do tego celu wykorzystano hierarchiczną procedurę minimalizacji przy zastosowaniu analizy wrażliwości. Analiza numeryczna potwierdziła efektywność...
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Experimental and numerical identification of corrosion degradation of ageing structural components
PublikacjaThe study presents experimental and numerical identification of corrosion degradation of thin-walled structural components employing guided wave propagation. The steel structural components are subjected to through-thickness varying corrosion degradation levels. The developed approach using the non-destructive guided wave-propagation quantifies the equivalent average corrosion degradation level by exploring a limited number of...
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On reliability assessment of ship machinery system in different autonomy degree; A Bayesian-based approach
PublikacjaAnalyzing the reliability of autonomous ships has recently attracted attention mainly due to epistemic uncertainty (lack of knowledge) integrated with automatic operations in the maritime sector. The advent of new random failures with unrecognized failure patterns in autonomous ship operations requires a comprehensive reliability assessment specifically aiming at estimating the time in which the ship can be trusted to be left unattended....
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Actual field corrosion rate of offshore structures in the Baltic Sea along depth profile from water surface to sea bed
PublikacjaThe paper presents the results of field electrochemical investigations on the corrosion rate of carbon steel in seawater of the Baltic Sea at the location of the Baltic Beta production rig. The measurements were conducted throughout the year in seawater at different depths from the sea surface to the sea bed (about 75 m). The results revealed corrosion aggressiveness of the seawater along the entire depth profile. There was...
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Enhancing seismic performance of rigid and semi-rigid connections equipped with SMA bolts incorporating nonlinear soil-structure interaction
PublikacjaNowadays, using smart connections can improve the performance of buildings with some recentering features that are from the superelastic behavior of Shape Memory Alloys (SMAs). It seems that there is different rigidity between the designed connection and the real one in Steel Moment-Resisting Frames (SMRFs), which can be considered as a problematic issue due to the importance of connections in seismic performance assessment. This...
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Full-scale CFD simulations for the determination of ship resistance as a rational, alternative method to towing tank experiments
PublikacjaResults of ship resistance predictions obtained from towing tank experiments are affected by the method used to extrapolate from a model scale to a ship scale. Selection of method to determine a form factor is subjective and the extrapolation method is accurate for typical hull forms. For innovative hull forms the proper method for calculating the form factor is questionable. Moreover, the influence of the extrapolation method...
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A fast start-up of the organotrophic anammox process inoculated with constructed wetland sediment
PublikacjaOrganotrophic anaerobic ammonium oxidation (anammox) bacteria can utilize small volatile fatty acids with nitrate as electron acceptors with less energy consumption and no biomass production. To achieve a faster and stable start-up of organotrophic anammox process, in this study, the growth of organotrophic anammox bacteria seeded from hybrid constructed wetland (CW) sediment under different TOC/TN ratios and different chloramphenicol...
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25 years of research and experiences about the application of constructed wetlands in southeastern Poland
PublikacjaThis paper is a review of research and experiences related to the application of constructed wetland systems (CWs) in southeastern Poland in 1992–2016. On the basis of literature data, a comparison between pollutant removal efficiencies of one-stage and hybrid CWs was made. Some problems regarding the operation of these treatment plants were also presented. Data from various facilities indicate that one-stage CWs with horizontal...
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Reduced-cost surrogate modelling of compact microwave components by two-level kriging interpolation
PublikacjaFull-wave electromagnetic (EM) analysis is a versatile tool for evaluating the performance of high-frequency components. Its potential drawback is its high computational cost, inhibiting the execution of EM-driven tasks requiring massive simulations. The applicability of equivalent network models is limited owing to the topological complexity of compact microstrip components because of EM cross-coupling effects. Development of...
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Fast tolerance-aware design optimization of miniaturized microstrip couplers using variable-fidelity EM simulations and re-sponse features
PublikacjaManufacturing tolerances and other types of uncertainties may considerably affect operation and performance of microwave components and systems. Quantification of these effects is therefore an important part of the design process. It is even more important to obtain designs whose sensitivity to parameter deviations is reduced as much as possible. All of these require statistical analysis carried out at the level of electromagnetic...
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Geotechnical characterization of soft soil deposits in Northern Poland
PublikacjaThis paper presents a geotechnical characterization of deltaic soft soil deposits in the Vistula Marshlands, northern Poland. It shows the limited applicability of organic soil classifications based on Cone Penetration Tests (CPTU) and Dilatometer Tests (DMT). None of the in-situ-based classifications correctly identifies peat. Analysis of the behaviour of contractive/dilative soil layers according to Robertson's updated classification...
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Full scale measurements of pressure field induced on the quay wall by bow thrusters – indirect method for seabed velocities monitoring
PublikacjaThe paper presents the results of full-scale experimental investigation of loads generated on the quay wall by bow thrusters during unberthing of a self-manoeuvring vessel. The presented research allowed for the comparison of the measurements results with generally accepted empirical prediction methods and confirmed the utility of the developed measuring setup for the on-line monitoring of jet induced loads. The conclusions from the...
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Prediction of manoeuvring abilities of 10000 DWT pod-driven coastal tanker
PublikacjaThis paper aims to present a new approach in the prediction of manoeuvring abilities of pod-driven ships. A new mathematical model of motions based on MMG methodology was developed and a new type of description of forces acting on azimuth drives is presented. Captive model tests of medium-size coastal tanker and pod open water tests were carried out in CTO S.A. (Ship Design and Research Centre S.A.) to obtain hull hydrodynamic derivatives...
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Equivalent standard manoeuvres for pod-driven ships
PublikacjaProcedures for carrying out the manoeuvring tests presented in International Maritime Organisation (IMO) resolution MSC.137(76) are based on the capabilities of ships with conventional steering-propulsion systems. Therefore they do not correspond to ships with other steering-propulsion devices, like pod drives. IMO is aware of this shortcoming and for ships with non-conventional steering and propulsion system may permit the use...
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Polish experience in operation of sludge treatment reed beds
PublikacjaSludge Treatment Reed Beds (STRBs) is the technology of sludge treatment, which is based on natural processes occurring in the environment, in specially designed and operated facilities to achieve benefits for the environment. Integrated dewatering and stabilization occur in reed systems. For economic and environmental reasons it is an attractive solution, especially in rural areas where there are no appropriate facilities. In...
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The efficiency and reliability of pollutant removal in a hybrid constructed wetland with giant miscanthus and Jerusalem artichoke in Poland
PublikacjaIn this paper, we analysed the pollutant removal efficiency and reliability of a vertical and horizontal flow hybrid constructed wetland (CW) planted with giant miscanthus and Jerusalem artichoke. The wastewater treatment plant, located in south-eastern Poland, treated domestic sewage at an average flow rate of 1.2m3·d−1. The tests were carried out during. 5-years of operation of the sewage treatment plant (2011–2016). During this...
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A Time Delay Controller Included Terminal Sliding Mode and Fuzzy Gain Tuning for Underwater Vehicle-Manipulator Systems
PublikacjaAn improved Time Delay Control (TDC) method for an Underwater Vehicle-Manipulator System (UVMS) is proposed. The proposed controller consists of three terms: a time-delay-estimation term that cancels nonlinearities of the UVMS dynamics, a Terminal Sliding Mode (TSM) term that provides a fast response and a PID term that reduces the tracking error. In addition the proposed controller uses fuzzy rules to adaptively tune the gains...
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Determination of Chemical Oxygen Demand (COD) at Boron-doped Diamond (BDD) Sensor by Means of Amperometric Technique
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Application of Bayesian Networks for Forecasting Future Model of Farm
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44 Years Hindcast of the sea level and circulation in the Baltic Sea
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Three-dimensional structure of wave-induced momentum flux in irrotational waves in combined shoaling-refraction conditions
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Wind-wave variability in a shallow tidal sea—Spectral modelling combined with neural network methods
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Labour Consumption of Production of Selected Fruit
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Verification of Economic and Agricultural Indicators With the Use of Statistical Methods on the Example of Individual Farms
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Phase-decoupled refraction–diffraction for spectral wave models
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