Search results for: START-STOP REGIME
-
Sensorless low speed PMSM motor control with cogging torque compensation
PublicationThe paper presents sensorless control of a low speed permanent magnet synchronous machine with use of modified state observer. An overview of the PMSM motor used in the research setup was presented. The problem of drive torque ripple, resulting mainly from the occurrence of a significant cogging torque, was discussed. A solution compensating the torque ripple of the PMSM motor was proposed. A start-up procedure of the speed control...
-
Integrated safety and security analysis of hazardous plants and systems of critical infrastructure
PublicationThis article addresses an integrated safety and security analysis approach of hazardous industrial plants and systems of critical infrastructure. Nowadays due to new hazards that emerge there are opinions among experts that these issues require an integrated approach in life cycle, from the design concept, through the design and operation of the plant, to its decommissioning. It is proposed to start from an interesting methodology...
-
Three phase transient model of wet coal pyrolysis
PublicationA one-dimensional transient mathematical model was developed to describe the thermal and flow phenomena during coal pyrolysis in a coke oven. The model was solved numerically using partly implicit methods for gas flow and heat transfer problems. It was successfully validated with industrial-scale measurements of temperature change in the middle-plane of the coke oven chamber. The evolution of temperature and pressure, distributions...
-
COMPARISON OF TWO MODELS OF CONDENSATION
PublicationIn the low-pressure part of steam turbine, the state path usually crosses the saturation line in penultimate stages. At least last two stages of this part of turbines operate in two –phase region. The liquid phase in this region in mainly created in the process of homogeneous and heterogeneous condensation. Several observations confirm however, that condensation often occurs earlier than it is predicted by theory i.e. before the...
-
Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines. Part I: Steady-state processes
PublicationThe article presents a possible method of detecting failures in the flow section and supply system of a naval gas turbine engine based on the exhaust gas temperature measured behind the gas generator. This temperature is a basic diagnostic parameter use for evaluating the technical state of the turbine engine in operation, and is monitored during engine start-ups, accelerations and decelerations of rotor units, and steady-load...
-
Ocena odporności na zużycie ścierne stopów Ti na elementy pary trącej endoprotez stawu kolanowego
PublicationNajczęściej stosowanym biomateriałem tytanowym na elementy endoprotez stawu kolanowego jest stop Ti6Al4V. Z uwagi na zawartość wanadu, zaliczanego do pierwiastków o dużej toksyczności podejmowane są działania w kierunku zastąpienia wskazanego stopu - stopami bezwanadowymi. Jednym z najbardziej obiecujących jest stop Ti13Nb13Zr zawierający w swoim składzie jedynie pierwiastki witalne, niewywołujące stanów zapalnych i odczynów...
-
Thermgravimetric analysis (TGA) data of cement pastes containing pristine and silica-coated bismuth oxide and gadolinium oxide particles
Open Research DataThermogravimetric (TGA) data of cement pastes after 2, 7 and 28 days. Samples designations: Control, BG, BG-A and BG-B are associated with the specimen names in the associated publication.
-
Ac and dc conductivities in v2o5-p2o5 glasses containing alkaline ions
PublicationWe investigated the ac and dc conductivity in 50V2O5-(50 − x)P2O5-xA2O (A = Li, Na, K) glasses as a function of temperature. The measurements were carried out in the frequency range from 10−4 to 107 Hz. For all compositions, the dc conductivity decreased with the increasing alkali ion content. The decrease in conductivity was more pronounced for larger alkali ions. The ac conductivity exhibited a universal dynamic response: σac...
-
Spinon excitations in the quasi-one-dimensional S=12 chain compound Cs4CuSb2Cl12
PublicationThe spin−1/2 Heisenberg antiferromagnetic chain is ideal for realizing one of the simplest gapless quantum spin liquids (QSLs), supporting a many-body ground state whose elementary excitations are fractional fermionic excitations called spinons. Here we report the discovery of such a one-dimensional (1D) QSL in Cs4CuSb2Cl12. Compared to previously reported S=1/2 1D chains, this material possesses a wider temperature range over...
-
Objectivity in the non-Markovian spin-boson model
PublicationObjectivity constitutes one of the main features of the macroscopic classical world. An important aspect of the quantum-to-classical transition issue is to explain how such a property arises from the microscopic quantum theory. Recently, within the framework of open quantum systems, there has been proposed such a mechanism in terms of the so-called spectrum broadcast structures. These are multipartite quantum states of the system...
-
Centrally Pivoted Tilting Pad Thrust Bearing with Carbon-Based Coated Collar—Experimental Results of Low- and Medium-Speed Operation
PublicationExperimental results of the research on a tilting pad thrust bearing with symmetrical pad support in the conditions of high loads and low speeds are presented in the paper. As described in the literature review, experimental results of tilting pad bearings at low speed/high load regime and transient conditions are rare. Unusual material selection - steel pad against a DLC-type coating on the collar was utilized. Such material combination...
-
Modelling reinforced concrete beams under mixed shear-tension failure with different continuous FE approaches
PublicationThe paper presents quasi-static numerical simulations of the behaviour of short reinforced concrete beams without shear reinforcement under mixed shear-tension failure using the FEM and four various constitutive continuum models for concrete. First, an isotropic elasto-plastic model with a Drucker-Prager criterion defined in compression and with a Rankine criterion defined in tension was used. Next, an anisotropic smeared crack...
-
A constitutive law for concrete with smooth transition from continuous into discontinuous cracks’ description
PublicationPaper presents a constitutive model for concrete that combines a continuous and discontinuous crack’s description to simulate the concrete under tensile dominated loads. In a continuum regime, two different constitutive laws were used. First, a plasticity model with the Rankine failure criterion and an associated flow rule was used. Second, a constitutive law based on isotropic damage mechanics was formulated. Both model alternatives...
-
Mikołaj Nowak dr inż.
PeopleDr inż. Mikołaj Nowak uzyskał stopień naukowy doktora nauk technicznych w dyscyplinie Automatyka, Elektronika i Elektrotechnika w roku 2021. Pracuje jako adiunkt na Wydziale Elektrotechniki i Automatyki Politechniki Gdańskiej. Jego zainteresowania badawcze i zawodowe obejmują systemy energii skierowanej i ich zastosowanie do celów neutralizacji zagrożeń elektronicznych, układy impulsowe o wielkiej gęstości mocy i energii, systemy...
-
NEW SOLUTIONS FOR THE SOLAR CHARGE CONTROLLERS DESIGN FOR OBTAINING TRUE MPP IN PARTLY SHADED PV MODULES
PublicationSoft shading sources such as tree limbs, structural elements of buildings and chimneys, scatter and refract sunlight, significantly reducing the amount of radiation reaching the surface of the module. The hard shadings located directly on the surface (i.e. bird droppings, leaves, snow) tend to stop sunlight completely. These phenomena significantly affects the output characteristics of photovoltaic modules and often contribute...
-
Machine learning approach to packaging compatibility testing in the new product development process
PublicationThe paper compares the effectiveness of selected machine learning methods as modelling tools supporting the selection of a packaging type in new product development process. The main goal of the developed model is to reduce the risk of failure in compatibility tests which are preformed to ensure safety, durability, and efficacy of the finished product for the entire period of its shelf life and consumer use. This kind of testing...
-
Erwin Wojtczak dr inż.
People -
Paid work activity and entrepreneurial cognitions of students – evidence from European emerging economies
PublicationPurpose – This paper aims to investigate whether paid work activity (PWA) experience of students from five emerging economies is related to academic results and self-assessment of possessed entrepreneurial traits. Additionally, the authors verify the relationship between obtaining work experience and the willingness to start own business among students. Design/methodology/approach – Participants included 3,631 students of the first...
-
A Systematic Literature Review on Implementing Non-functional Requirements in Agile Software Development: Issues and Facilitating Practices
PublicationAgile Software Development methods have become a widespread approach used by the software industry. Non-functional requirements (NFRs) are often reported to be a problematic issue for such methods. We aimed to identify (within the context of Agile projects): (1) the issues (challenges and problems) reported as affecting the implementation of NFRs; and (2) practices that facilitate the successful implementation of NFRs. We conducted...
-
Action Plan “Women”
PublicationEmployees of a company are not the first alternative coming into one’s mind when searching suitable successor for the business. Those belonging to the company’s management group are in many cases asked for their interest in being a successor, but the lower level an employee is in the hierarchy, the less probably he/she is inquired of his/her interest in becoming a successor. The contemporary entrepreneur may have had conflicts...
-
Collision-free network exploration
PublicationMobile agents start at different nodes of an n-node network. The agents synchronously move along the network edges in a collision-free way, i.e., in no round two agents may occupy the same node. An agent has no knowledge of the number and initial positions of other agents. We are looking for the shortest time required to reach a configuration in which each agent has visited all nodes and returned to its starting location. In...
-
Morphology and the physical and thermal properties of thermoplastic polyurethane reinforced with thermally reduced graphene oxide
PublicationIn this study, thermally reduced graphene oxide (TRG)-containing polyurethane nanocomposites were obtained by the extrusion method. The content of TRG incorporated into polyurethane elastomer systems equaled 0.5, 1.0, 2.0 and 3.0 wt%. The morphology, static and dynamic mechanical properties, and thermal stability of the modified materials were investigated. The application of TRG resulted in a visible increase in material stiffness...
-
Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines. Part III. Diagnostic and operating tolerances
PublicationThe third part of the article presents a method for detecting failures of the automatic engine control system with the aid of an exhaust gas temperature setter, specially designed and machined for this purpose. It also presents a procedure of identifying the operating tolerances and determining the diagnostic tolerances for the exhaust gas temperature recorded in the naval turbine engine during the start-up and acceleration processes....
-
Effect of austempering temperature on microstructure and cyclic deformation behaviour of multiphase low-carbon steel
PublicationThis paper examined the cyclic deformation behaviour of multiphase low-carbon steel that was subjected to austempering heat treatments at four temperatures (190 °C, 230 °C, 275 °C, and 315 °C) below the martensite start temperature (Ms = 353 °C). The tests were conducted at room temperature, under fully reversed strain-controlled conditions, with strain amplitudes in the range 0.5–1.0%. The microstructure was observed by transmission...
-
Influence of temperature and nitrogen pressure on the test without active gases for high-temperature proton exchange membrane fuel cells
PublicationHigh-Temperature Proton-Exchange Membrane Fuel Cells (HT-PEMFCs) are a candidate for electrical energy supply devices in more and more applications. Most notably in the aeronautic industry. Before any use, an HT-PEMFC is preheated and after that supplied with its active gases. Only at this state, the diagnostics can be performed. A method of testing not requiring a complete start-up would be beneficial for many reasons. This article...
-
Changes on the Surface of the SiO2/C Composite, Leading to the Formation of Conductive Carbon Structures with Complex Nature of DC Conductivity
PublicationSol–gel layers have been the subject of many studies in recent decades. However, very little information exists about layers in which carbon structures are developed in situ. Using the spin-coating method, we obtained thin iron-doped SiO2/C composite films. The results of Raman spectroscopy showed that our samples consisted of graphitic forms and polymers. The latter’s contribution decreases with rising temperature. FTIR and EDS...
-
Chemometric Assessment and Best-Fit Function Modelling of the Toxic Potential of Selected Food Packaging Extracts
PublicationFood packaging materials constitute an ever more threatening environmental pollutant. This study examined options to specifically assess the ecotoxicity of packaged wastes, such as cans, subjected to various experimental treatments (in terms of extraction media, time of exposure, and temperature) that imitate several basic conditions of the process of food production. The extracts were studied for their ecotoxicity with bioluminescent...
-
Size effect in concrete beams under bending – influence of the boundary layer and the numerical description of cracks
PublicationIn the paper the size effect phenomenon in concrete is analysed. The results of numerical simulations of using FEM on geometrically similar un-notched and notched concrete beams under bending are presented. Concrete beams of four different sizes and five different notch heights under three-point bending test were simulated. In total 18 beams were analysed. Two approaches were used to describe cracks in concrete. First, eXtended...
-
Magneto-thermal convection of low concentration nanofluids
PublicationThe main aim of this paper was to analyze possible utilization of the low concentration nanofluids and the magnetic field to enhance heat transfer. The studied fluids were based on water with an addition of copper particles (40-60 nm diameter). They belonged to the diamagnetic group of materials. As a first attempt to stated target the analysis of enclosure placed in the maximal value of square magnetic induction gradient was carried...
-
Numerical analyses of novel prefabricated structural wall panels in residential buildings based on laboratory tests in scale 1:1
PublicationThe paper presents experimental and numerical investigations on novel prefabricated composite building wall panels for residential building constructions. The wall panels were composed of reinforced concrete ribbed elements with the core from the EPS foam as the thermal insulation. The wall panels in the full-scale 1:1 were subjected to vertical loads. In the first step, the experiments were analysed with simple usual static methods....
-
Dynamiczna aplikacja Internetowa ASP.NET silnika indukcyjnego jako elementu wirtualnego laboratorium maszyn elektrycznych
PublicationTematem referatu jest dynamiczna aplikacja internetowa, która umożliwia symulację obwodową silnika indukcyjnego trójfazowego Sg 100 L2 z wykorzystaniem interfejsu przeglądarki WWW. Model matematyczny silnika jest zdefiniowany w tzw. osiach naturalnych i sformułowany na podstawie metody energetycznej Lagrange’a. Do implementacji modelu maszyny w aplikacji internetowej wybrano projekt typu Web Forms, który jest składnikiem środowiska...
-
Dynamiczne wyznaczanie parametrów elektrycznego obwodu szeregowego
PublicationPo załączeniu napięcia na skutek istnienia inercji prąd w obwodzie zaczyna narastać od wartości zerowej do znamionowej. W tym czasie narastają spadki napięć na rezystancjach (impedancjach obwodu) do chwili spełnienia prawa Kirchhoffa. Można utworzyć układ ze sprzężeniem zwrotnym (układ regulacji stałowartościowej bądź nadążnej), który poszukuje parametrów obwodu spełniających prawa Kirchhoffa – elementy nie muszą być liniowe. W...
-
Wpływ wybranych właściwości maszyny badawczej na wynik eksperymentu tribologicznego z tarciem ślizgowym
PublicationNiniejsza monografia stanowi podsumowanie przekrojowych badań związanych z wpływem właściwości stanowiska badawczego (tribometru) na przebieg i rejestrowane wyniki eksperymentu tribologicznego z tarciem ślizgowym ciał stałych smarowanych cieczą w warunkach tarcia bez efektów smarowania hydrodynamicznego. Autor przedstawia wyniki kompleksowych analiz właściwości dynamicznych stanowiska badawczego w kontekście efektów obserwowanych...
-
SimLE SimBa SimLE SimBa: Start eksperymentalnych rakiet sondujących z ładunkiem naukowym na międzynarodowych konkursach konstruktorskich.
ProjectsProject realized in Sekretariat Dziekana WIMiO
-
Experimental and comparative study on the two-phase pressure drop of air-water mixture in U-bend and straight pipe annuli
PublicationIn this paper, the experimental and theoretical analysis of pressure drop in singlephase and two phase-flow were presented for straight and U-bend smooth tube annulus and tube annulus with wire coil insert. Experiments for various boundary conditions were performed. In case of U-tube and straight tube with and without turbulator, tests were made for the water-water and air-water systems. The study covered a wide measuring range,...
-
Spectacular Oxygen Evolution Reaction Enhancement through Laser Processing of the Nickel‐Decorated Titania Nanotubes
PublicationThe selective, laser‐induced modification of the nickel‐decorated titania nanotubes provides remarkable enhancement toward oxygen evolution reaction. Particularly, the irradiation of the laterally spaced crystalline TiO2 nanotubes, results in the formation of the tight closure over irradiated end, preserving their hollow interior. The shape of the absorbance spectra is modulated along with applied energy, and the new absorption...
-
Spectacular Oxygen Evolution Reaction Enhancement Through Laser Processing of the Nickel-Decorated Titania Nanotubes
PublicationThe selective, laser-induced modification of the nickel-decorated titania nanotubes provides remarkable enhancement toward oxygen evolution reaction. Particularly, the irradiation of the laterally spaced crystalline TiO2 nanotubes, results in the formation of the tight closure over irradiated end, preserving their hollow interior. The shape of the absorbance spectra is modulated along with applied energy, and the new absorption...
-
Predicting Ice Phenomena in a River Using the Artificial Neural Network and Extreme Gradient Boosting
PublicationForecasting ice phenomena in river systems is of great importance because these phenomena are a fundamental part of the hydrological regime. Due to the stochasticity of ice phenomena, their prediction is a difficult process, especially when data sets are sparse or incomplete. In this study, two machine learning models—Multilayer Perceptron Neural Network (MLPNN) and Extreme Gradient Boosting (XGBoost)—were developed to predict...
-
Removal of persistant organic pollutants from landfill leachates treated in three constructed wetland systems
PublicationThe objective of the study was assessment of occurrence and removal of two groups of persistent organic pollutants: polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in landfill leachate (LL) treated in three constructed wetland systems (CWs) of different construction and flow regime. Two subsurface flow systems (SSF) were analyzed: one with horizontal flow and the second one consisting of two vertical...
-
Evaluation of organic coatings condition with AFM-based method
PublicationThe paper presents an atomic force microscopy (AFM)-based approach to evaluation of local protective properties of organic coatings. Apart from topography, it provides local ac and dc characteristics of examined coating. The method consists in application of ac voltage perturbation signal between conductive AFM tip and coated metal substrate. The resulting current is used to determine local impedance characteristics. Both impedance...
-
Analysis of the Surface Stereometry of Alloyed Austenitic Steel after Fibre Laser Cutting using Confocal Microscopy
PublicationThe paper extends the concept of cut edge quality and examines the fibre laser cutting process. A Prima Power Platino Fiber Evo device with a reference speed (RS) of 3500 mm/min was used for laser cutting. In order to analyse the influence of the laser cutting speed on the cut edge quality of X5CrNi18-10 stainless steel sheets, macroscopic studies were conducted on a stereoscopic microscope and surface stereometry on a confocal...
-
A coupled constitutive model for fracture in plain concrete based on continuum theory with non-local softening and eXtended Finite Element Method
PublicationThe paper presents a constitutive model for concrete which combines a continuous and discontinuous fracture description. In a continuum regime, two different constitutive laws were used. First, a plasticity model with a Rankine failure criterion and an associated fl ow rule was used. Second, a constitutive law based on isotropic damage mechanics was formulated. In order to capture the width of a localized zone and to obtain mesh-independent...
-
Mechanical Design, Construction and Control of a Lower Extremity Exoskeleton Robot Prototype with a new structure in the form of three-wheeled Mobile robot
PublicationIn this paper, mechanical design, dynamic modeling, construction and Fuzzy computed torque control of a lab prototype of lower extremity exoskeleton robot with a new structure in the form of three-wheeled Mobile robot is presented. One of the most important applications of next generation of lower extremity exoskeleton robot is usability as smart vehicle. In order to autonomously moving of this robot which is the foundation...
-
Collaborative Exploration of Trees by Energy-Constrained Mobile Robots
PublicationWe study the problem of exploration of a tree by mobile agents (robots) that have limited energy. The energy constraint bounds the number of edges that can be traversed by a single agent. We use a team of agents to collectively explore the tree and the objective is to minimize the size of this team. The agents start at a single node, the designated root of the tree and the height of the tree is assumed to be less than the energy...
-
Buzz-based recognition of the honeybee colony circadian rhythm
PublicationHoneybees are one of the highly valued pollinators. Their work as individuals is appreciated for crops pollination and honey production. It is believed that work of an entire bee colony is intense and almost continuous. The goal of the work presented in this paper is identification of bees circadian rhythm with a use of sound-based analysis. In our research as a source of information on bee colony we use their buzz that have been...
-
Fractional Order Circuit Elements Derived from Electromagnetism
PublicationIn this paper, derivations of fractional-order (FO) circuit-element equations from electromagnetism are presented. Whilst many papers are devoted to FO modelling of electrical circuits, there are no strong foundations for such an approach. Therefore, we investigate relations between the FO electromagnetism and the FO circuit theory. Our derivations start from quasi-static (QS) approximations of Maxwell's equations in media with...
-
Design and distribution of air nozzles in the biomass boiler assembly
PublicationDue to energy crisis as well as increasing pollution of the environment, renewable energy sources usage increases all over the world. These facts encouraged authors to start research over developing a uniform biomass boiler calculation model. This paper presents a design of biomass boiler assembly created for ORC (Organic Rankine Cycle) unit since these systems could achieve strong position in energy industry....
-
Trigger-based Model to Assess the Readiness of IT Organizations to Agile Transformation
PublicationThe process of change the method of project management from waterfall to agile is called “agile transformation” (AT). The decision to agile transformation is undertaken based on many different factors. Many companies decide to abandon classic, waterfall methodology for agile without prior analysis. This approach makes the processes of agile transformation is hard to control and frequently the implementation of agile fails. The...
-
On extending open source IMS platform for integrated IPTV and VoIP services over IPv6
PublicationEven when IMS is the most popular platform for multimedia services, the open versions of IMS ecosystem are lacking in specified functionalities for IPTVv6 and VoIPv6 services. In this paper, we extend current client and server open source software in order to provide reliability and security to these multimedia services. As a part of our work the IMS architecture for conferencing system with proposed mechanisms to improve system...
-
Networking and Familiness as Factors Stimulating the Early Internationalization of High-Tech Firms
PublicationThe problem of the role and importance of time in the process of firm’s internationalization belongs to the mainstream of international business research, as is the problem of the key role of high-tech firms operating across borders. The main goal of the paper is to understand how selected factors determine early internationalization of high-tech firms in Poland as an emerging market. The theoretical framework of the article is...