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Wyniki wyszukiwania dla: current source inverter
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Mechanical properties of the human stomach under uniaxial stress action
PublikacjaThe aim of this study was to estimate the range of mechanical properties of the human stomach in order to use the collected data in numerical modelling of surgical stapling during resections of the stomach. The biomedical tests were conducted in a self-developed tensile test machine. Twenty-two fresh human stomach specimens were used for the experimental study of its general strength. The specimens were obtained from morbidly obese...
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Direct brain stimulation modulates encoding states and memory performance in humans
PublikacjaPeople often forget information because they fail to effectively encode it. Here, we test the hypothesis that targeted electrical stimulation can modulate neural encoding states and subsequent memory outcomes. Using recordings from neurosurgical epilepsy patients with intracranially implanted electrodes, we trained multivariate classifiers to discriminate spectral activity during learning that predicted remembering from forgetting,...
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Psychological capital and happiness at work: The mediating role of employee thriving in multinational corporations
PublikacjaWorking in multicultural work environments of multinational corporations (MNCs) creates challenges whose expected impact on happiness is equivocal. In the following paper, we examine the relationship between psychological capital and happiness at work in the specific MNCs’ context. We assume that thriving (eudemonic well-being) at work fosters individuals’ development and enhances their happiness composed of both the affective...
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A method of selecting light sources from night satellite scenes
PublikacjaSatellite images carries a lot of data. Very sophisticated methods of analyses may reveal very complicated nature of the observed objects. In case of night images, lights play the role of information sources. In this paper we would like to present results of the research aimed to describe light sources from satellite night images by providing description of their luminosity. The authors point source imaging data from the satellite...
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POLLUTANTS PRESENT IN DIFFERENT COMPONENTS OF THE SVALBARD ARCHIPELAGO ENVIRONMENT
PublikacjaDuring last years an interest in the processes of transport and fate of pollutants to the polar regions located distantly from industrial centers, has significantly increased. The current analytical techniques enabling conducting studies prove that the Arctic regions (in the past considered as a pollution free area) have become an area of highly intensive anthropopresion. Svalbard archipelago stands out from the other polar regions...
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FDTD Simulations on Disjoint Domains with the Use of Discrete Green's Function Diakoptics
PublikacjaA discrete Green's function (DGF) approach to couple disjoint domains in the finite-difference time-domain (FDTD) grid is developed. In this method, total-field/scattered-field (TFSF) FDTD domains are associated with simulated objects whereas the interaction between them is modeled with the use of the DGF propagator. Hence, source and scatterer are simulated in separate domains and updating of vacuum cells, being of little interest,...
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Ancient settlements-atavistic solutions for present water supply and drainage problems engendered by urbanism
PublikacjaWater is the most valuable resource available on earth. Although it is present in abundance, its usable volume is very scarce. This is the reason behind the existence of both floods and droughts around the world. However, human settlements face water scarcity issues that are primarily engendered by improper town planning measures. To create a balance between the available fractions of water, it is therefore imperative to have proper...
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Database of speech and facial expressions recorded with optimized face motion capture settings
PublikacjaThe broad objective of the present research is the analysis of spoken English employing a multiplicity of modalities. An important stage of this process, discussed in the paper, is creating a database of speech accompanied with facial expressions. Recordings of speakers were made using an advanced system for capturing facial muscle motion. A brief historical outline, current applications, limitations and the ways of capturing face...
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Low cost set-up for supercapacitors parameters evaluation
PublikacjaWe propose a use of a power amplifier in the circuit of voltage to current converter (current driver) for supercapacitor charging/discharging in controlled conditions. The current driver is controlled by DAC output of DAQ board and voltage of DUT is measured and a control loop is realized by software. In the circuit the DC current method of evaluation of capacitance and equivalent series...
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Modelling of the Heat Flux Density Distribution for Laser Beam Welding
PublikacjaGreat interest of the laser beam welding in industry is a new theoretical task, making planning the welding procedure specification and the quality control of welded joints easier. Estimating and calculating the dimensions of a weld pool and temperature distribution near weld mainly concern heat source modelling. In the presented work calculations of welding pool shape and thermal field for cylindrical-powered-normally model of...
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Edible black ant Smith (Carebara vidua) as human food – A systematic review
PublikacjaMeeting food security is one of the major global challenges to ensure sufficient supply of food for current and future generations, considering increasing population growth and climate change issues. Consequently, the consumption of edible insects as an alternative food source has recently gained global attention for combating global food insecurity. The present review aims to provide information on the recent progress in consumption...
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Amplifying the Randomness of Weak Sources Correlated With Devices
PublikacjaThe problem of device-independent randomness amplification against no-signaling adversaries has so far been studied under the assumption that the weak source of randomness is uncorrelated with the (quantum) devices used in the amplification procedure. In this paper, we relax this assumption, and reconsider the original protocol of Colbeck and Renner using a Santha-Vazirani (SV) source. To do so, we introduce an SV-like condition...
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Anatomia systemu ERP. Rynek, praktyczne zastosowanie oraz bezpieczeństwo systemów Enterprise Resource Planning
PublikacjaTematem niniejszej pracy stał się rynek, praktyczne zastosowanie otwartych systemów ERP w przedsiębiorstwach oraz jego bezpieczeństwo dokonane na podstawie wybranych przykładów z artykułów naukowych oraz dostępnej literatury przedmiotu. Celem pracy jest udzielenie odpowiedzi na pytania: Jakie są dotychczasowe rozwiązania systemowe w przedsiębiorstwach? Jakie są zalety stosowania systemów ERP Open Source? Jakie...
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Low cost set-up for supercapacitors parameters evaluation
PublikacjaSupercapacitors are capable to store relatively high amount of energy comparing to its mass. Growing number of these devices applications requires development of new testing methods. Standard methods of evaluation of supercapacitor parameters, as cycling voltammetry, CV, galvanostatic cycling with potential limitation, GCPL, impedance measurements, require equipment of high cost...
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Cascaded Buck Hybrid Interlink Converter for Multiple-Input / Multiple-Output Operation
PublikacjaThe provision of isolated- and non-isolated DC output voltages by Power electronics power-conditioning devices in the recent ‘green-energy-revolution’ era is on course. In this paper, a structure for multi-input multi-output(MIMO) DC–DC buck converter is proposed to generate output voltages of varying levels with fewer component-count. The DC output voltage of each of the constituting buck converters can be used independently or...
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The Possibility of Phase Change Materials (PCM) Usage to Increase Efficiency of the Photovoltaic Modules
PublikacjaSolar energy is widely available, free and inexhaustible. Furthermore this source of energy is the most friendly to the environment. For direct conversion of solar energy into useful forms like of electricity and thermal energy, respectively photovoltaic cells and solar collectors are being used. Forecast indicate that the first one solution will soon have a significant part in meeting the global energy demand. Therefore it is...
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Computer System for Evaluation of Shock Hazard in Circuits with Non-sinusoidal Earth Currents
PublikacjaEffects of current on people are mainly considered for 50/60 Hz sinusoidal current and smooth direct current. However, modern low voltage circuits are very often equipped with power electronics converters – rectifiers, frequency converters, therefore non-sinusoidal earth currents (touch currents) occur. For non-sinusoidal currents safety criteria should be modified. This paper presents a computer system, based on LabVIEW environment,...
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Higher harmonics produced by traction substations – computer modelling and experimental verification
PublikacjaVoltage and current harmonics have a detrimental effect on the components of a power system. Current harmonics may result in the overload and damage to power transformers, although the rms value of load current does not exceed their current-carrying capacity. Voltage harmonics may result in, for example, damage to capacitor banks used to compensate reactive power. Devices which contribute to both current and voltage distortion...
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Evaluation of VSC Impact on Power System Using Adequate P-Q Capability Curve
PublikacjaRenewable energy sources, which are becoming increasingly popular, often use a voltage source converter (VSC) for connection to the power system. Assessing the effects of connecting such a source to the power system is essential to ensure the proper operation of the power system and the connected source. For this purpose, it is necessary to know the range of active and reactive power generation by the converter. The authors indicate...
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Applications of the discrete green's function in the finite-difference time-domain method
PublikacjaIn this paper, applications of the discrete Green's function (DGF) in the three-dimensional (3-D) finite-difference time-domain (FDTD) method are presented. The FDTD method on disjoint domains was developed employing DGF to couple the subdomains as well as to compute the electromagnetic field outside these subdomains. Hence, source and scatterer are simulated in separate subdomains and updating of vacuum cells, being of little...
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The impedance of hydrogen oxidation reaction in a proton exchange membrane fuel cell in the presence of carbon monoxide in hydrogen stream
PublikacjaEvaluation of performance of a proton exchange membrane fuel cell, which is affected by carbon monoxide that pollutes the hydrogen stream, was presented. This influence was studied for carbon monoxide concentration of 125–325 ppb, which are close to values specified in ISO 14687:2019 standard. Performed studies provided crucial information for further development of fuel cell as an energy source for automotive application. Impedance...
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Sustainable Use of the Catenary by Trolleybuses with Auxiliary Power Sources on the Example of Gdynia
PublikacjaThe current developments in onboard power source technology, in particular, traction batteries, open up new potential in trolleybus transport and also make it possible to introduce electric buses. Thus far, trolleybus transport has required the presence of overhead lines (OHL). Introducing trolleybuses with onboard batteries makes it possible to grow the zero-emissions transport network in places with limited power supply capabilities...
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The impact of air humidity on the operation of proton exchange membrane fuel cells determined using dynamic electrochemical impedance spectroscopy
PublikacjaThis paper describes the changes in the fuel cell impedance across a range of current loads and humidity changes. The changes of each equivalent circuit parameters representing specific processes occurring in fuel cells, as a function of humidity and current changes, were determined. Within the combined scope of current and humidity, the optimal working conditions of the cells were determined, corresponding to the lowest impedance...
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Optimal configuration of an electrode array for measuring ventricles' contraction
PublikacjaAn influence of an electrode-array configuration on an impedance signal composition for a fixed spatial distribution of its sources is examined in the paper. The Finite Element Method and Geselowitz relationship were used for examining three different electrode-arrays. A sensitivity approach was used to evaluate each configuration assuming that localization of the signal source is known. A conductivity change, thus the source of...
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Arching of railway turnouts by analytical design method
PublikacjaThe paper involved the issue of arching of the railway turnouts. This is an issue which is given relatively less attention to scientific and research activities. Reference has been made to the book by Wladyslaw Rzepka, under the title „Curved turnouts in plan and profile”, which has been used in Poland for more than 50 years as the main source of information relating to the turnouts on the curve. The book is a compilation of elaborations...
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Analytical design method for widening the intertrack space
PublikacjaThe paper involved the issue of arching of the railway turnouts. This is an issue which is given relatively less attention to scientific and research activities. Reference has been made to the book by Wladyslaw Rzepka, under the title „Curved turnouts in plan and profile”, which has been used in Poland for more than 50 years as the main source of information relating to the turnouts on the curve. The book is a compilation of elaborations...
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Sensorless predictive control of three-phase parallel active filter
PublikacjaThe paper presents the control system of parallel active power filter (APF) with predictive reference current calculation and model based predictive current control. The novel estimator and predictor of grid emf is proposed for AC voltage sensorless operation of APF, regardless of distortion of this voltage. Proposed control system provides control of APF current with high precision and dynamics limited only by filter circuit parameters....
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Reactive Energy Billing in Operator Tariffs in Poland
PublikacjaThe paper describes the current method of reactive energy billing in the tariffs of distribution grid operators in Poland. The current solutions are subject to critical assessment. Issues related to the motivation effect of the current solutions on consumers are analysed. Problems that occur in relation with connecting distributed generators to the distribution grid and challenges related to prosumer billing are indicated.
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Use of LIDAR Data in the 3D/4D Analyses of the Krakow Fortress Objects
PublikacjaThe article presents partial results of studies within the framework of the international project "Cultural Heritage Through Time" (CHT2). The subject of the study were forts of the Krakow Fortress, which had been built by the Austrians between 1849-1914 in order to provide defence against the Russians. Research works were aimed at identifying architectural changes occurring in different time periods in relation to selected...
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NARAŻENIA NAPIĘCIOWE SILNIKÓW INDUKCYJNYCH ZASILANYCH Z FALOWNIKÓW NAPIĘCIA
PublikacjaW artykule przedstawiono zagadnienia związane z narażeniami izolacji silników pracujących w układach napędowych z falownikami napięcia. Znaczne stromości napięć oraz zjawiska falowe w przewodach zasilających powodują przyspieszoną degradacje izolacji maszyn. Rozwiązaniem jest stosowanie filtrów biernych na wyjściu falownika.
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Stanowisko do diagnostyki i regulacji wyzwalaczy przekaźników w obwodach lokomotyw elektrycznych
PublikacjaFast circuit breaker and protective relays play an important role of protecting locomotive’s electrical circuits from damage caused by short circuit or overload. Undisturbed operation and proper circuit protection depends on the technical condition and fine calibration of the over-current trips. Therefore the relays should be subject to periodic inspection and adjustment due to locomotive maintenance schedule. A test stand for...
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The effects of urban vehicle traffic on heavy metal contamination in road sweeping waste and bottom sediments of retention tanks
PublikacjaDiffuse pollution formed during a surface runoff on paved surfaces is a source of heavy metals (HMs) of various origin. This research study indicates the connection between bottom sediments of retention tanks located on urban streams and road sweeping wastes (RSW) that migrate during surface runoff to the stormwater drainage systems with discharge to the retention tanks. Moreover, we test the primary sources of HMs in RSW by analysing...
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Comparison of experimental results with simulation studies of "digital" hydrostatic transmission
PublikacjaThe publication presents the results of experimental research on a "digital" hydrostatic transmission conducted at INOE 2000 IHP within the framework of the grant "Method of effective use of the digital hydraulics concept in multi-source hydrostatic drive systems". The primary goal of the research is to compare the effectiveness (efficiency) of using different methods of controlling the pump capacity and the hydraulic motor capacity...
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Microbe Cultivation Guidelines to Optimize Rhamnolipid Applications
PublikacjaIn the growing landscape of interest in natural surfactants, selecting the appropriate one for specific applications remains challenging. The extensive, yet often unsystematized, knowledge of microbial surfactants, predominantly represented by rhamnolipids (RLs), typically does not translate beyond the conditions presented in scientific publications. This limitation stems from the numerous variables and their interdependencies...
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Modified GAPI (MoGAPI) Tool and Software for the Assessment of Method Greenness: Case Studies and Applications
PublikacjaThe green analytical procedure index (GAPI) has been widely used to assess the greenness of different steps in analytical methodology. In the GAPI index, the different stages of the chemical analysis process are depicted using five pentagrams divided in subsections, labeled green, yellow, or red according to the degree of greenness. This GAPI tool provides a quick overview of the environmental impact and safety of the procedure....
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A case study of odour nuisance evaluation in the context of integrated urban planning
PublikacjaOdour nuisance poses a serious problem in many urban areas, yet its evaluation and mitigation is often omitted in the urban planning process. By identifying its range and spatio-temporal variations, it could be taken into consideration by planners in urban development strategies and land use decisions. The aim of the study was to present the application of odour evaluation techniques in the improvement of the quality of life in...
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Synthesis of malonylenamides and thiomalonylenamides
Publikacja5-[Hydroksyl(aryl(amino))methylene]-2,2-dimethyl-1,3-dioxane-4,6-dione is convenient source of ketenes which can be trapped with various nucleophiles like alcohols, thiols and amines. In reaction between in situ generated ketene and enolizable imines we can easily obtain corresponding malonylenamides. This facile method can be used to obtain thiomalonylenamides using 5-[sulfhydrylo(alkyl(amino))methylene]-2,2-dimethyl-1,3-dioxane-4,6-dione...
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Experimental and numerical analysis of the pyrolysis dynamics of a single wood particle: presentation of the radiographic technique
PublikacjaPyrolysis is an oxygen-free process for the thermal decomposition of raw materials. The heat conduction and flow of pyrolysis products (i.e., the gas fraction and liquid vapour generated during pyrolysis) influence the process and products. In this work, the influence of the orientation of wooden particle fibres with respect to the direction of the heat source on the dynamics of the process was investigated, where there were two...
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TIME-AND-SPACE STRUCTURE OF FORCE-DRIVEN RIGID SPHEREWAVEFIELD
PublikacjaThis paper introduces a time-domain, causality-inspired description of a vector-source acoustic wavefield of arbitrary time evolution, where a sphere is a practical realisation of quasi-point contact surface without which a point force would not be able to exert an impact onto non-viscous fluid. At every space location, the resulting acoustic field is described by a pair of physical variables characterising the time evolution of...
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The Method of Multi-criteria Analysis to Support the Decision on Load or Micro-generation Connection to a Low- or Medium-voltage Power Grid
PublikacjaThis paper presents a method that supports the decision in terms on selecting the best option of a load connection to a low- or medium-voltage power distribution grid, and of a micro-generation source connection to a low-voltage grid. The method is based on the search for the option with the lowest aggregate assessment measure, which is the weighted average of partial assessment measures determined for each of eight considered...
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Accuracy of the discrete Green's function computations
PublikacjaThis paper discusses the accuracy of the discrete Green's function (DGF) computations. Recently closed-form expression of the DGF and its efficient numerical implementation were presented which facilitate the DGF applications in FDTD simulations of radiation and scattering problems. By carefully comparing the DGF results to those of the FDTD simulation, one can make conclusions about the range of the applicability of the DGF for...
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Low Cost Hexacopter Autonomous Platform for Testing and Developing Photogrammetry Technologies and Intelligent Navigation Systems
PublikacjaLow-cost solutions for autonomous aerial platforms are being intensively developed and used within geodetic community. Unmanned aerial vehicles are becoming very popular and widely used for photogrammetry and remote sensing applications. Today’s market offers an affordable price components for unmanned solution with significant quality and accuracy growth. Every year market offers a new solutions for autonomous platforms with better...
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Metrological analysis of an computerized system of protection against electric shock in circuits with variable speed drives
PublikacjaDrive systems, that can be operated at variable speed, are equipped with power electronics converters. This causes distortion of the earth current, and consequently the need to take into account the use of proper protective devices in relation to earth current harmonics. This paper presents a system for protection against electric shock in circuits with power electronics converters and metrological analysis indicating the requirements...
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Use of Neural Networks in Diagnostics of Rolling-Element Bearing of the Induction Motor
PublikacjaBearing defect is statistically the most frequent cause of an induction motor fault. The research described in the paper utilized the phenomenon of the current change in the induction motor with bearing defect. Methods based on the analysis of the supplying current are particularly useful when it is impossible to install diagnostic devices directly on the motor. The presented method of rolling-element bearing diagnostics used indirect...
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MCSA with Normalized Triple Covariance as a bearings diagnostic indicator in an induction motor
PublikacjaStatistics of bearing failures in induction motors indicate, that they constitute more than 40% of IM damage, therefore bearing diagnosis is very important. Vibration methods for bearing diagnostics have one major disadvantage - they require the availability of the machine for sensors installation. This is the reason for seeking new methods based on motor supply current analysis. Diagnosis of induction motors, conducted remotely...
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Harmonics produced by traction substations – computer modelling and experimental verification
PublikacjaVoltage and current harmonics have a detrimental effect on the components of a power system. Current harmonics may result in the overload and damage to power transformers. Voltage harmonics may result in, for example, damage to capacitor banks used to compensate reactive power. Devices which contribute to both current and voltage distortion include traction rectifiers. This paper presents results of the computer investigation of...
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Recent advances on SOA formation in indoor air, fate and strategies for SOA characterization in indoor air - A review
PublikacjaRecent studies proves that indoor air chemistry differs in many aspects from atmospheric one. People send up to 90 % of their life indoors being exposed to pollutants present in gas, particle and solid phase. Particle phase indoor is composed of particles emitted from various sources, among which there is an indoor source – secondary chemical reactions leading to formation of secondary organic aerosol (SOA). Lately, researchers'...
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Operational Performance and Weld Bead Characteristics of Experimental Tubular-Wires for Underwater Welding
PublikacjaAiming to evaluate new formulations and their operational behavior underwater, two experimental tubular wires with different chemical compositions in their internal flux were initially manufactured, employing a pilot machine and a unique manufacturing process. Weld beads were deposited on a plate placed in a flat position inside a tank using a mechanized system and the IMC 300 welding power source. The work was done at a depth...
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Accuracy of a low-cost autonomous hexacopter platforms navigation module for a photogrammetric and environmental measurements
PublikacjaA photogrammetry and environmental measurements from an unmanned aerial vehicle (UAV) are a low-cost alternative for a traditional aerial photogrammetry. A commercial off-the-shelf products (COTS) offers a variety of cheap components that a suitable to be used on board a UAV. In this paper a low-cost navigation module based on Ublox NEO-M8N GPS and Pixhawk flight controller have been described, as a main extrinsic parameters source...
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A Stand for Measurement and Prediction of Scattering Properties of Diffusers
PublikacjaIn this paper we present a set of solutions which may be used for prototyping and simulation of acoustic scattering devices. A system proposed is capable of measuring sound field. Also a way to use an open source solution for simulation of scattering phenomena occurring in proximity of acoustic diffusers is shown. The result of our work are measurement procedure and a prototype of the simulation script based on FEniCS - an open source...