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total: 716
filtered: 646
Search results for: DISTURBANCE, STABILITY ANALYSIS, SLIDING MODE OBSERVER, SUPER TWISTING.
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Identification of dynamic parameters in the context of diagnostics of steel tank with different level of liquid.
PublicationThe paper presents an experimental study to identify the dynamic parameters of a water-filled tank model. The experimental modal analysis approach involving the excitation at one point of the structure and acquisition of vibra tions at selected points distri buted over the tank surface allowed to determine the resonance frequencies, mode shapes and damping ratios. The main aim of the research was to examine the influence of...
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Measurement system for nonlinear surface spectroscopy by atomic force microscopy for corrosion processes monitoring
PublicationIn addition to traditional imaging the surface, atomic force microscopy (AFM) enables wide variety of additional measurements. One of them is higher harmonic imaging. In tapping mode the nonlinear contact between tip and specimen results in higher frequency vibrations. More information available from the higher harmonics analysis proves to be helpful for more detailed imaging. Such visualization is especially useful for heterogeneous...
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Multi-source-supplied parallel hybrid propulsion of the inland passenger ship STA.H. Research work on energy efficiency of a hybrid propulsion system operating in the electric motor drive mode
PublicationIn the Faculty of Ocean Engineering and Ship Technology, Gdansk University of Technology, design has recently been developed of a small inland ship with hybrid propulsion and supply system. The ship will be propelled by a specially designed so called parallel hybrid propulsion system. The work was aimed at carrying out the energy efficiency analysis of a hybrid propulsion system operating in the electric motor drive mode and at...
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Modal Analysis of Planar Elliptical Resonator Deposited on Unshielded Dielectric Slab
PublicationModal analysis of isolated open planar elliptical patch placed on dielectric slab is presented in the paper. It applies concept of Illuminating Modes which is formulated for the case of two-side opened structure. The current on patch is expanded in basis functions in form of Mathieu radial and angular functions. The spectrum of excited modes for exemplary planar resonators is presented and discussed using the concept of power of...
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A SEARCH OF AN INDUCER GEOMETRY THAT IS BENEFICIAL FOR LIFTING PARAMETERS OF A LIFTED OBJECT OF A SELECTED SHAPE
PublicationThe literature describes acoustic levitation phenomena with the utilization of air squeeze film between the vibrating inducer and the lifted object. The objective of the study is to determine the shape of the inducer with vibration characteristics that would allow the levitation of an object of the assumed geometry. In this paper, the influence of the dimension ratio of the inducer on the frequency of the first mode of vibration...
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Series Passive Compensation of Common Mode Voltage in Multilevel Inverter Drives
PublicationThis paper presents an approach to the problem of a magnetic saturation of CM chokes that accompanies the method of passive compensation of a common mode (CM) voltage in an inverter drive system. Measurements have been provided in a drive system including multilevel inverters and the filter having sinusoidal output voltages and zero CM voltage. The theoretical analysis and experimental results show that the problem with magnetic...
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Uproszczone metody obliczania wyboczenia silosów z blachy falistej wzmocnionych słupami na podstawie analizy MES i wyników doświadczalnych
PublicationRozprawa doktorska dotyczy zagadnienia stateczności i nośności granicznej stalowych silosów z płaszczem z blachy falistej wzmocnionych pionowymi słupami. Przeprowadzono zaawansowane analizy numeryczne MES oraz badania doświadczalne dotyczące wyboczenia/stateczności analizowanych silosów. Analizy numeryczne zostały przeprowadzone w zakresie liniowej oraz nieliniowej analizy stateczności, z uwzględnieniem wstępnych imperfekcji geometrycznych...
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Ternary Bismuthide SrPtBi2: Computation and Experiment in Synergism to Explore Solid-State Materials
PublicationA combination of theoretical calculation and the experimental synthesis to explore the new ternary compound is demonstrated in the Sr–Pt–Bi system. Because Pt–Bi is considered as a new critical charge-transfer pair for superconductivity, it inspired us to investigate the Sr–Pt–Bi system. With a thorough calculation of all the known stable/metastable compounds in the Sr–Pt–Bi system and crystal structure predictions, the thermodynamic...
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Automatic Emotion Recognition in Children with Autism: A Systematic Literature Review
PublicationThe automatic emotion recognition domain brings new methods and technologies that might be used to enhance therapy of children with autism. The paper aims at the exploration of methods and tools used to recognize emotions in children. It presents a literature review study that was performed using a systematic approach and PRISMA methodology for reporting quantitative and qualitative results. Diverse observation channels and modalities...
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THE METHOD OF ANALYSIS OF DAMAGE REINFORCED CONCRETE BEAMS USING TERRESTRIAL LASER SCANNING
PublicationThe authors present an analysis of the possibility to assess deformations and mode of failure of R-C beams using terrestrial laser scanning. As part of experiments carried out at the Regional Laboratory of Construction (at Gdansk University of Technology), reinforced concrete beams were subjected to destruction by bending and by shear. The process of press impact on the reinforced concrete beam was recorded using terrestrial laser...
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Investigation of buckling resistance of columns using non-linear static and dynamic analysis
PublicationThe aim of this paper is to investigate the stability process in an axially compressed column using a static and dynamic finite element analysis by taking both the geometric and material non-linearity into account. The perfect column and column with geometric imperfections were analysed. The linear buckling analyses were used to obtain the lowest buckling load and shapes of buckled forms that were taken into account as initial...
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Production of certified reference materials - homogeneity and stability study based on the determination of total mercury and methylmercury
PublicationReference materials (RMs) play an important role in all elements of the quality assurance system of measurements. In this work, ``package'' 4 new CRMs (bottom sediment, herring tissue, cod tissue, cormorant tissue) were prepared and characterised to carry out the quality control in monitoring analysis of mercury and methylmercury in environmental samples. Materials - candidates were collected in Poland and south part of the Czech...
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On the plastic buckling of curved carbon nanotubes
PublicationThis research, for the first time, predicts theoretically static stability response of a curved carbon nanotube (CCNT) under an elastoplastic behavior with several boundary conditions. The CCNT is exposed to axial compressive loads. The equilibrium equations are extracted regarding the Euler–Bernoulli displacement field by means of the principle of minimizing total potential energy. The elastoplastic stress-strain is concerned...
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Examination of Spectral Properties of Medicinal Plant Leaves Grown in Different Lighting Conditions Based on Mint Cultivation
PublicationCultivation in controlled environmental conditions can provide good quality medicinal herbs with consistent properties. A sensing system that can determine the contents of medicinal substances in plants using spectral characteristics of leaves would be a valuable tool. Viability of such sensing approach for mint had to be confirmed experimentally, as no data correlating contents of medicinal substances with spectral characteristics...
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Porosity and shape of airborne wear microparticles generated by sliding contact between a low-metallic friction material and a cast iron
PublicationThe wear of brakes in transport vehicles is one of the main anthropogenic sources of airborne particulate matter in urban environments. The present study deals with the characterisation of airborne wear microparticles from a low-metallic friction material / cast iron pair used in car brakes. Particles were generated by a pin-on-disc machine in a sealed chamber at sliding velocity of 1.3 m/s and contact pressure of 1.5 MPa. They...
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Surface active fatty acid ILs: Influence of the hydrophobic tail and/or theimidazolium hydroxyl functionalization on aggregates formation
PublicationNine structurally-related fatty acid ionic liquids have been prepared and their thermal behavior as well as their ability to self-assemble in water has been investigated. The thermal properties were studied by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), while the aggregation behavior was analyzed by tensiometry, isothermal titration calorimetry (ITC), conductometry, dynamic light scattering (DLS),...
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A measurement system for nonlinear surface spectroscopy with an atomic force microscope during corrosion process monitoring
PublicationIn addition to traditional imaging the surface, atomic force microscopy (AFM) enables wide variety of additional measurements. One of them is higher harmonic imaging. In tapping mode the nonlinear contact between tip and specimen results in higher frequency vibrations. More information available from the higher harmonics analysis proves to be helpful for more detailed imaging. Such visualization is espe-cially useful for heterogeneous...
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Methodological issues of functional safety and reliability assessment of critical systems in industrial hazardous plants
PublicationThe aim of this article is to identify and discuss some methodological issues that are of interest among functional safety specialists and experts after publication of the second edition of international standards IEC 61508 and IEC 61511, including the design and implementing the safety-related functions of higher safety integrity levels and protection layers. The basic role of safety-related systems is to reduce effectively and...
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A nine-input 1.25 mW, 34 ns CMOS analog median filter for image processing in real time
PublicationIn this paper an analog voltage-mode median filter, which operates on a 3 × 3 kernel is presented. The filter is implemented in a 0.35 μm CMOS technology. The proposed solution is based on voltage comparators and a bubble sort configuration. As a result, a fast (34 ns) time response with low power consumption (1.25 mW for 3.3 V) is achieved. The key advantage of the configuration is relatively high accuracy of signal processing,...
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Determination of pharmaceuticals in fish: method optimization and occurrence in different species from Mediterranean rivers
PublicationThe multi-residue analytical method developed, based on accelerated solvent extraction, gel permeation chromatography purification and UPLC-MS/MS analysis allowed the simultaneous determination of 21 pharmaceuticals. Recoveries obtained for most of the target compounds were higher than 50%. The application of UPLC-MS/MS operating in the MRM mode, with two transitions monitored for each compound, provided good sensitivity and selectivity....
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Application of soil nailing technique for protection and preservation historical buildings
PublicationSoil nailing is one of the recent in situ techniques used for soil improvement and in stabilizing slopes. The process of soil nailing consists of reinforcing the natural ground with relatively small steel bars or metal rods, grouted in the pre-drilled holes. This method has a wide range of applications for stabilizing deep excavations and steep slopes. Soil nailing has recently become a very common method of slope stabilisation...
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Innovative Gathering and Energy Management System Integrated within PV Module
PublicationThe dynamic development of battery technology and design based on the flow of lithium ions, mainly driven by the needs of the automotive industry leads to the Conclusion That they are becoming a more viable alternative to traditional lead-acid batteries. Their use is driven by the ability it quickly charge and discharge times higher durability, maintenance-free operation and much smaller dimensions as well as weight. The emergence...
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The use of Response Surface Methodology for reliability estimation of composite engineering structures
PublicationStability loss is one of the key issues in the analysis of shells made of composite materials. This paper aims at finding the variation of the critical or limit value of the load resulting from geometric imperfections. An axially compressed 16-layer cylindrical panel model is considered. The imperfections of the panel are simulated as random fields. The parameters of these fields are used as the basic variables of the reliability...
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SrCe0.9In0.1O3-δ-based reversible symmetrical Protonic Ceramic Cell
PublicationIn-doped SrCe0.9In0.1O3-δ (SCI) perovskite-type oxide is utilized as the solid electrolyte, as well as a component, together with SrFe0.75Mo0.25O3-δ (SFM) compound, in the composite-type electrodes to construct symmetrical Protonic Ceramic Fuel Cells (PCFC). With good mutual stability of SCI and SFM at high temperatures in water vapor-containing reducing and oxidizing conditions, as well as sufficient ionic conductivity with high...
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COMPUTER-AIDED DESIGN OF ORGANOPHOSPHORUS INHIBITORS OF UREASE
PublicationBased on the structure of the most potential inhibitor diamidophosphate, various novel groups of inhibitors were developed by knowledge-based design approach with covalent carbon-phosphorus or carbon-phosphorus-carbon bond to improve hydrolytic stability to inhibit the microbial ureases. Designed compounds were evaluated with 10 (LigScore1, LigScore2, PLP1, PLP2, JAIN, PMF, PMF04, LUDI_1, LUDI_2 and LUDI_3) different scoring functions...
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Broken rotor bar impact on sensorless control of induction machine
PublicationThe aim of the research is analysis of the sensorless control system of induction machine with broken rotor for diagnostic purposes. Increasing popularity of sensorless controlled variable speed drives requires research in area of reliability, range of stable operation, fault symptoms and application of diagnosis methods. T transformation (Cunha et al.,2003) used for conversion of instantaneous rotor currents electrical circuit...
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Reduction of Computational Complexity in Simulations of the Flow Process in Transmission Pipelines
PublicationThe paper addresses the problem of computational efficiency of the pipe-flow model used in leak detection and identification systems. Analysis of the model brings attention to its specific structure, where all matrices are sparse. With certain rearrangements, the model can be reduced to a set of equations with tridiagonal matrices. Such equations can be solved using the Thomas algorithm. This method provides almost the same values...
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Weighted difference schemes for systems of quasilinear first order partial functional differential equations
PublicationThe paper deals with initial boundary value problems of the Dirichlet type for system of quasilinear functional differential equations. We investigate weighted difference methods for these problems. A complete convergence analysis of the considered difference methods is given. Nonlinear estimates of the Perron type with respect to functional variables for given functions are assumed. The proof of the stability of difference problems...
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Computer-aided analysis of resonance risk in power system with Static Var Compensators
PublicationStatic Var Compensators operation in a power system may significantly improve voltage profiles in nodes and the reactive power balance, as well as ensure greater system stability in emergency conditions. However these devices may be a cause of a resonance in the system. The aim of this paper is to call attention to the need to include resonance phenomena in a compensator’s location evaluation process. The analysis performed in...
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Fiber optic microsphere with a ZnO thin film for potential application in a refractive index sensor – theoretical study
PublicationOptical fiber sensors of refractive index play an important role in analysis of biological and chemical samples. This work presents a theoretical investigation of spectral response of a fiber optic microsphere with a zinc oxide (ZnO) thin film deposited on the surface and evaluates the prospect of using such a structure for refractive index sensing. A microsphere is fabricated by an optical fiber tapering method on the base of...
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Analytical ‘Steady-State’-Based Derivation and Clarification of the Courant-Friedrichs-Lewy Condition for Pipe Flow
PublicationThis article addresses the problem of choosing the optimal discretization grid for emulating fluid flow through a pipeline. The aggregated basic flow model is linearized near the operating point obtained from the steady state analytic solution of the differential equations under consideration. Based on this model, the relationship between the Courant number (μ) and the stability margin is examined. The numerically set coefficient...
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Ground tire rubber thermo-mechanically devulcanized in the presence of waste engine oil as asphalt modifier
PublicationCross-linked elastomers network is main limitation for industrial usage of ground tire rubber (GTR) as asphalts’ and road pavements modifier. GTR was thermo-mechanically devulcanized via extrusion in the presence of waste engine oil (WEO) at temperature ranges from 150 to 280 °C. Combined impact of WEO content and extruder barrel temperature on the change of cross-linked structure of degraded GTR (DTGR) was investigated through...
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Galvanostatic impedance measurements for the efficient adsorption isotherm construction in corrosion inhibitor studies
PublicationWe present an approach towards an accurate and time-efficient adsorption isotherm determination to evaluate the corrosion inhibitor interaction in electrolytic environments. The approach is based on dynamic impedance spectroscopy measurements in galvanostatic mode (g-DEIS). The studied corrosion inhibitor is continuously injected between the secondary cell and the corrosion cell. The efficiency corresponding to instantaneous inhibitor...
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POM/EVA Blends with Future Utility in Fused Deposition Modeling
PublicationPolyoxymethylene (POM) is one of the most popular thermoplastic polymers used in the industry. Therefore, the interest in its potential applications in rapid prototyping is understandable. Nevertheless, its low dimensional stability causes the warping of 3D prints, limiting its applications. This research aimed to evaluate the effects of POM modification with ethylene-vinyl acetate (EVA) (2.5, 5.0, and 7.5 wt.%) on its processing...
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Non-linear static stability of bi-layer carbon nanosheets resting on an elastic matrix under various types of in-plane shearing loads in thermo-elasticity using nonlocal continuum
PublicationIn this research, the shear and thermal buckling of bi-layer rectangular orthotropic carbon nanosheets embedded on an elastic matrix using the nonlocal elasticity theory and non-linear strains of Von-Karman was studied. The bi-layer carbon sheets were modeled as a double-layered plate, and van der Waals forces between layers were considered. The governing equations and boundary conditions were obtained using the first order shear...
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Material Parameters Identification of Historic Lighthouse Based on Operational Modal Analysis
PublicationIn the present paper, the identification of the material parameters of a masonry lighthouse is discussed. A fully non-invasive method was selected, in which the material properties were determined via numerical model validation applied to the first pair of natural frequencies and their related mode shapes, determined experimentally. The exact structural model was built by means of the finite element method. To obtain experimental...
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Cycling as a Sustainable Transport Alternative in Polish Cittaslow Towns
PublicationIt is well known that growing motor traffic in urban areas causes air pollution and noise which affects the environment and public health. It is hardly surprising then that cycling should be used as an alternative mode of transport, not just in major cities but also in smaller ones including those that are members of the Cittaslow network. Their approach is based on sustainable development, care for the environment and transport...
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Features extraction from the electrocatalytic gas sensor responses
PublicationOne of the types of gas sensors used for detection and identification of toxic-air pollutant is an electrocatalytic gas sensor. The electrocatalytic sensors are working in cyclic voltammetry mode, enable detection of various gases. Their response are in the form of I-V curves which contain information about the type and the concentration of measured volatile compound. However,...
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Flexural behavior of composite structural insulated panels with magnesium oxide board facings
PublicationThe current report is devoted to the flexural analysis of a composite structural insulated panel (CSIP) with magnesium oxide board facings and expanded polystyrene (EPS) core, that was recently introduced to the building industry. An advanced nonlinear FE model was created in the ABAQUS environment, able to simulate the CSIP’s flexural behavior in great detail. An original custom code procedure was developed, which allowed to include...
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Sustainable upcycling of brewers’ spent grain by thermo-mechanical treatment in twin-screw extruder
PublicationThermo-mechanical treatment of brewers’ spent grain (a by-product of beer manufacturing) was successfully performed via the extrusion process. The impact of temperature (from 30 to 180 °C), throughput (from 1 to 5 kg/h) and screw speed (from 75 to 375 rpm) on particle size, color, chemical structure, antioxidant activity and thermal stability of resulting material, as well as correlations between particular properties, were investigated....
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Enhancing colloidal stability of nanodiamond via surface modification with dendritic molecules for optical sensing in physiological environments
PublicationPre-treatment of diamond surface in low-temperature plasma for oxygenation and in acids for carboxylation was hypothesized to promote the branching density of the hyperbranched glycidol polymer. This was expected to increase the homogeneity of the branching level and suppress interactions with proteins. As a result, composite nanodiamonds with reduced hydrodynamic diameters that are maintained in physiological environments were...
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Catalytic Activity of Nickel and Ruthenium–Nickel Catalysts Supported on SiO2, ZrO2, Al2O3, and MgAl2O4 in a Dry Reforming Process
PublicationDry reforming of methane (DRM) is an eco-friendly method of syngas production due to the utilization of two main greenhouse gases—methane and carbon dioxide. An industrial application of methane dry reforming requires the use of a catalyst with high activity, stability over a long time, and the ability to catalyze a reaction, leading to the needed a hydrogen/carbon monoxide ratio. Thus, the aim of the study was to investigate the...
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Computational analysis of substituent effects on proton affinity and gas-phase basicity of TEMPO derivatives and their hydrogen bonding interactions with water molecules
PublicationThe study investigates the molecular structure of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its derivatives in the gas phase using B3LYP and M06-2X functional methods. Intermolecular interactions are analyzed using natural bond orbital (NBO) and atoms in molecules (AIM) techniques. NO2-substituted TEMPO displays high reactivity, less stability, and softer properties. The study reveals that the stability of TEMPO derivatives...
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TIME- AND FREQUENCY-DOMAIN QUASI-2D SMALL-SIGNAL MOSFET MODELS
PublicationA novel approach to small-signal MOSFET modeling is presented in this book. As a result, time- and frequency-domain physics-based quasi-2D NQS four-terminal small-signal MOSFET models are proposed. The time-domain model provides the background to a novel DIBL-included quasi‑2D NQS four-terminal frequency-domain small-signal MOSFET model. Parameters and electrical quantities of the frequency-domain model are described by explicit...
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Grid-Forming Operation of Energy-Router Based on Model Predictive Control with Improved Dynamic Performance
PublicationThe focus of this study is on the grid-forming operation of the Energy Router (ER) based on Model Predictive Control (MPC). ER is regarded as a key component of microgrids. It is a converter that interfaces the microgrid (s) with the utility grid. The ER has a multiport structure and bidirectional energy flow control. The ER concept can be implemented in Nearly Zero-Energy Buildings (NZEB) to provide flexible energy control. A...
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The Concept of a Methodology for Selecting the Optimal Parameters of Heat Received from a Nuclear Power Plant Operating in a Partial Cogeneration Mode
PublicationThe paper presents the concept of the objective function which is to allow the selection of optimal parameters of the district heating system using a nuclear power plant operating in partial cogeneration mode. The concept is based on research carried out a number of years ago. The size of annual expenses was proposed as the objective function, which allows to compare the operation of a nuclear power plant in partial cogeneration...
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Buckling of thin-walled columns accounting for initial geometrical imperfections
PublicationThe paper is devoted to the effect of some geometrical imperfections on the critical buckling load of axially compressed thin-walled I-columns. The analytical formulas for the critical torsional and flexural buckling loads accounting for the initial curvature of the column axis or the twist angle respectively are derived. The classical assumptions of theory of thin-walled beams with non-deformable cross-sections are adopted. The...
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A new approach of coastal cliff monitoring using Mobile Laser Scanning
PublicationThe article proposes a new approach of coastal cliff monitoring which bases on a new comprehensive monitoring system, being a combination of mobile scanning from the sea with the geotechnical stability analysis. Mobile laser scanning is an innovative solution for 3D data collection which allows the monitored object geometry to be precisely measured, thus providing opportunities for series of analyses contributing to the development...
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The use of Response Surface Methodology for reliability estimation of aluminum silo subjected to wind load
PublicationAn axisymmetric aluminum silo model with a single, standardized geometric imperfection of its lateral surface is considered. The silo is wind – loaded only. The paper is focused on the critical, or limit value of wind pressure, both producing a loss of stability of the silo. This value is affected by vertical coordinate (position) of the imperfection and the angular relation between the imperfection and the wind direction. Reliability...
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Rola i znaczenie zbiornika sieciowego w kształtowaniu hydrauliki i jakości wody w systemie wodociągowym
PublicationEksploatacja zbiornika sieciowego powinna zapewniać cykliczną wymianę wody w jego komorach. Koniecznym warunkiem prawidłowej eksploatacji zbiornika jest zgodność założeń projektowych ze stanem faktycznym. Praktyka eksploatacyjna wskazuje na szereg nieprawidłowości w tym względzie. Z powodu lokalizacji zbiornika sieciowego za nisko lub za wysoko albo wskutek błędów popełnionych w ustaleniu jego parametrów obserwuje się niestabilność...