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Search results for: BANDWIDTH BROKER
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Numerically Efficient Miniaturization-Oriented Optimization of an Ultra-Wideband Spline-Parameterized Antenna
PublicationDesign of ultra-wideband radiators for modern handheld applications is a challenging task that involves not only selection of an appropriate topology, but also its tuning oriented towards balancing the electrical performance and size. In this work, a low-cost design of a compact, broadband, spline-parameterized monopole antenna has been considered. The framework used for the structure design implements trust-region-based methods,...
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Asymmetrical-Slot Antenna with Enhanced Gain for Dual-Band Applications
PublicationDual-band operation is an important feature of antennas to be applied in modern communication systems. Although high gain of radiators is rarely of concern in urban areas with densely located broadcasting stations, it becomes crucial for systems operating in more remote environments. In this work, a dual-band antenna with enhanced bandwidth is proposed. The structure consists of a driven element in the form of an asymmetrical radiator/slot...
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Evaluation of high-frequency roughness measurement errors for composite and ceramic surfaces after machining
PublicationPrecise characterisation of surface topography is of the greatest importance since many factors directly affect the accuracy of the whole measurement process. In this paper, the variety of surface topographies from machined composite and ceramic workpieces was studied with a special emphasis on the measurement results. Surfaces were subjected to the ground diamond, honing and milling processes. Measurement results were analysed...
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An Innovative Antenna Array with High Inter Element Isolation for Sub-6 GHz 5G MIMO Communication Systems
PublicationA novel technique is shown to improve the isolation between radiators in antenna arrays. The proposed technique suppresses the surface-wave propagation and reduces substrate loss thereby enhancing the overall performance of the array. This is achieved without affecting the antenna’s footprint. The proposed approach is demonstrated on a four-element array for 5G MIMO applications. Each radiating element in the array is constituted...
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Di-{bis(tri-tert-butoxysilanethiolato-S)(dimethylformamide-O)cadmium(II)}-μ-trans-1,2-di-4-pyridylethene-κ2N:N'
PublicationW przypadku tytułowego związku di-{bis(tri-tert-butoksysilanotiolano-S)(dimetylformamid-O)kadm(II)}-μ-trans-1,2-di-4-pirydyloeten [Cd(C12H27O3SSi)4(C3H7NO)2(C12H10N2)], centralny atom kadmu jest skoordynowany z czterema atomami donorowymi, tworząc rdzeń typu CdNOS2. Jest to pierwszy kompleks Cd(II) o tego typu centrum i ze względu na obecność dwóch reszt tiolanowych, N- i O-donora może on służyć za model centrum katalitycznego...
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Redetermination of bis(O,O′-diethyl dithiophosphato-κ2S,S′)nickel(II)
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Chlorido(4-morpholinecarbodithioato-k2S,S')(triphenylphosphine)nickel(II)
PublicationPrzeprowadzono syntezę oraz wyznaczono strukturę związku [Ni(C5H8NOS2)Cl(C18H15P)]. Tytułowy kompleks chloro(morfolinoditiokarbaminiano-S,S')(trifenylofosfina)-nikiel(II) posiada nieznacznie zniekształcony płaski kwadratowy rdzeń NiClS2P.
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Heteroleptic tri-tert-butoxysilanethiolate complexes of manganese(II) - thermal studies
PublicationThe thermal behavior of Mn(II) silanethiolate series [Mn(SR)2L(MeOH)n], where R=SSi(OBut)3, L=heterocyclic nitrogen base and n=0, 1 or 2 has been comparatively investigated using differential scanning calorimetry (DSC), thermogravimetry (TG) and TG-infrared spectoscopy (IR) techniques. The TG curves indicate the differences in the thermal decomposition due to presence of distinct N-donor ligands and labile MeOH molecules coordinated...
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Chlorido(1-pyrrolidinecarbodithioato-k2S,S')(triphenylphosphine)nickel(II)chloroform hemisolvate
PublicationTytułowy kompleks chloro(1-pirolidynoditiokarbaminiano-S,S')(trifenylofosfina)-nikiel(II), będący hemisolwatem chloroformu zawiera płaski rdzeń o składzie NiClS2P. Molekuły chloroformu oddziałują z kompleksem poprzez słabe wiązania C-H...S.
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Tris(1-pyrrolidinylcarbodithioato-S,S')-cobalt(III) chloroform disolvate
PublicationTytułowy kompleks tris(1-pirolidynoditiokarbaminiano-S,S')-kobalt(III), będący disolwatem chloroformu zawiera Co(III) oktaedrycznie skoordynowany przez trzy reszty ditiokarbaminowe. Molekuły chloroformu zaangażowane są w tworzenie cząsteczkami kompleksu oddziaływań typu C-H...S
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In search of molecular precursors for cadmium sulfide-new complexes with a sulfur-rich kernel: cadmium(II) tri-tert-butoxysilanethiolates with additional diethyldithiocarbamato ligand
PublicationW ramach rozprawy opracowano metodę syntezy związków koordynacyjnych kadmu zawierających mieszane ligandy S-donorowe, które stanowią reszta tri-tert-butoksysilanotiolanowa oraz ditiokarbaminianowa. Zostały one poddane badaniom za pomocą analizy składu pierwiastkowego, metod spektroskopowych (FTIR, FIR, UV-Vis, NMR, MS) oraz termicznych. W celu osadzenia cienkich warstw wybranych związków posłużono się techniką nakładania obrotowego...
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Crystal and molecular structure of bis(O,O'-diethyldithiophosphato-S,S')nickel(II): A redetermination
PublicationDoniesienie przedstawia ponownie wyznaczoną strukturę tytułowego, centrosymetrycznego kompleksu, [Ni{S2P(OC2H5)2}2]. Centralny rdzeń (S2P)2 jest płaski, co potwierdza wcześniejsze wyniki uzyskane przez McConnell'a i Kastalsky'ego, przy czym odchylenia standardowe są około siedmiokrotnie mniejsze oraz wyznaczono wszystkie pozycje atomów wodoru. W strukturze krystalicznej zaobserwowano róznież parę krótkich kontaktów HH (2.33 Å).
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Oligopeptide antifungals are exceptionally active against multidrug-resistant yeast
PublicationPermeazy peptydowe w komórkach drożdżowych są zdolne do transportu do wnętrza komórek oligopeptydów, zawierających w swojej strukturze niebiałkowe aminokwasy o właściwościach przeciwgrzybowych. Wśród szerokiego wachlarza tego rodzaju związków przebadanych pod względem aktywności biologicznej na wielolekoopornych komórkach drożdżowych, zaobserwowano liczna grupę, wykazującą zwiększoną aktywność względem komórek eksprymujących transportery...
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Thermal decomposition of [Cd{SSi(OBut)3}(S2CNC4H8)]2 to CdS “micro-noodles”
PublicationThis work presents studies on thermal degradation of novel heteroleptic complex possessing mixed S-donor ligands, [Cd{SSi(OBut)3}(S2CNC4H8)]2 using TGA, DSC, TGA-IR, SEM and XRD methods.
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New photocatalyst for decomposition of humic acids in photocatalysis and photo-Fenton processes
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Implementation of power transformer controlled switching algorithm
PublicationThe article presents two new algorithms of controlled switching the power transformer. The main aim of the paper is to obtain formulas that determine the moments of closing of the circuit breaker poles. The study contains projects of control systems for both algorithms. Mathematical formulas for the time instants of the breaker poles closing were developed on the basis of electric circuit theory and magnetic circuit theory. The...
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Friction-Induced Oscillations of a Non-Asbestos Organic Pin Sliding on a Steel Disc
PublicationFriction-induced oscillations result in deterioration of performance of disc brakes and are generally undesired. We conduct experimental study of friction-induced oscillations in a non-asbestos organic material / steel pair used in disc brakes of motor vehicles. The tests are done by use of a pin-on-disc machine which has the pin sample supported on a deformable beam. The adjustable friction parameters are the disc velocity, contact...
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An isogeometric finite element formulation for geometrically exact Timoshenko beams with extensible directors
PublicationAn isogeometric finite element formulation for geometrically and materially nonlinear Timoshenko beams is presented, which incorporates in-plane deformation of the cross-section described by two extensible director vectors. Since those directors belong to the space R3, a configuration can be additively updated. The developed formulation allows direct application of nonlinear three-dimensional constitutive equations without zero...
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Contact with coupled adhesion and friction: Computational framework, applications, and new insights
PublicationContact involving soft materials often combines dry adhesion, sliding friction, and large deformations. At the local level, these three aspects are rarely captured simultaneously, but included in the theoretical models by Mergel et al., (2019). We here develop a corresponding finite element framework that captures 3D finite-strain contact of two deformable bodies. This framework is suitable to investigate sliding friction even...
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A selectively reduced degree basis for efficient mixed nonlinear isogeometric beam formulations with extensible directors
PublicationThe effect of higher order continuity in the solution field by using NURBS basis function in isogeometric analysis (IGA) is investigated for an efficient mixed finite element formulation for elastostatic beams. It is based on the Hu–Washizu variational principle considering geometrical and material nonlinearities. Here we present a reduced degree of basis functions for the additional fields of the stress resultants and strains...
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Response to David Steigmann’s discussion of our paper
PublicationWe respond to David Steigmann's discussion of our paper "A general theory for anisotropic Kirchhoff-Love shells with in-plane bending of embedded fibers, Math. Mech. Solids, 28(5):1274-1317" (arXiv:2101.03122). His discussion allows us to clarify two misleading statements in our original paper, and confirm that its formulation is fully consistent with the formulation of Steigmann. We also demonstrate that some of our original statements...
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A general isogeometric finite element formulation for rotation‐free shells with in‐plane bending of embedded fibers
PublicationThis article presents a general, nonlinear isogeometric finite element formulation for rotation-free shells with embedded fibers that captures anisotropy in stretching, shearing, twisting, and bending - both in-plane and out-of-plane. These capabilities allow for the simulation of large sheets of heterogeneous and fibrous materials either with or without matrix, such as textiles, composites, and pantographic structures. The work...
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An isogeometric finite element formulation for frictionless contact of Cosserat rods with unconstrained directors
PublicationThis paper presents an isogeometric finite element formulation for nonlinear beams with impenetrability constraints, based on the kinematics of Cosserat rods with unconstrained directors. The beam cross-sectional deformation is represented by director vectors of an arbitrary order. For the frictionless lateral beam-to-beam contact, a surface-to-surface contact algorithm combined with an active set strategy and a penalty method...
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A design framework for rigorous constrained EM-driven optimization of miniaturized antennas with circular polarization
PublicationCompact radiators with circular polarization are important components of modern mobile communication systems. Their design is a challenging process which requires maintaining simultaneous control over several performance figures but also the structure size. In this work, a novel design framework for multi-stage constrained miniaturization of antennas with circular polarization is presented. The method involves sequential optimization...
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Advanced Sensor for Non-Invasive Breast Cancer and Brain Cancer Diagnosis Using Antenna Array with Metamaterial-Based AMC
PublicationMicrowave imaging techniques can identify abnormal cells in early development stages. This study introduces a microstrip patch antenna coupled with artificial magnetic conductor (AMC) to realize improved sensor for non-invasive (early-stage) breast cancer and brain cancer diagnosis. The frequency selectivity of the proposed antenna has been increased by the presence of AMC by creating an additional resonance at 2.276 GHz associated...
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Digital Transformation of Terrestrial Radio: An Analysis of Simulcasted Broadcasts in FM and DAB+ for a Smart and Successful Switchover
PublicationThe process of digitizing radio is far from over. It is an important interdisciplinary aspect, involving Big Data and AI (Artificial Intelligence) when it comes to classifying and handling content, and an organizational challenge in the Industry 4.0 concept. There exist several methods for delivering audio signals, including terrestrial broadcasting and internet streaming. Among them, the DAB+ (Digital Audio Broadcasting plus)...
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3D Metamaterial Ultra-Wideband Absorber for curved surface
PublicationThis paper proposes a three-dimensional metamaterial absorber based on a resistive film patch array to develop a low-cost, lightweight absorber for curved surfaces. An excellent absorption over a large frequency band is achieved through two different yet controllable mechanisms; In the first mechanism, a considerable attenuation in the wave power is achieved via graphite resistive films. The absorption is then intensified through...
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Overview of Metamaterials-Integrated Antennas for Beam Manipulation Applications: The Two Decades of Progress
PublicationMetamaterials (MMs) are synthetic composite structures with superior properties not found in naturally occurring materials. MMs have gained massive attention over the last two decades because of their extraordinary properties, such as negative permittivity and permeability. These materials enable many applications in communication subsystems, especially in the field of antenna design, to enhance gain, bandwidth, and efficiency,...
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Looking Up to the Stars. A Call for Action to Save New Zealand’s Dark Skies for Future Generations to Come
PublicationThe rapid development of technology coupled with humanity’s desire to reach beyond terra firma, has resulted in more than 60 years of Outer Space activities. Although the exploration of space has provided many advantages and benefits to society so far, including vast, new information that has greatly added to our understanding of our planet and beyond, unfortunately, mankind’s footprint has negative aspects that need to be minimised...
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The System of the Supervision and the Visualization of Multimedia Data for BG
PublicationMonitoring of country maritime border is an important task of the Border Guard. This task can be facilitated with the use of the technology enabling gathering information from distributed sources and its supervision and visualization. The system presented in the paper is an extension and enhancement of the previously developed distributed system map data exchange system. The added functionalities allow supplementation of map data...
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High Resolution Sea Ice Floe Size and Shape Data from Knox Coast, East Antarctica
PublicationThis dataset contains floe size distribution data from a very high resolution (pixel size: 0.3 m) optical satellite image of sea ice, acquired on 16 Feb. 2019 off the Knox Coast (East Antarctica). The image shows relatively small ice floes produced by wave-induced breakup of landfast ice between Mill Island and Bowman Island. The ice floes are characterised by a narrow size distribution and angular, polygonal shapes, typical...
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Rural Dwelling and Temporal Trends in Relation to Childhood Asthma and Related Conditions in Belarus: A Repeated Cross-sectional Survey
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Formation, crystal and molecular structures of heteroleptic zinc(II) tri-tert-butoxysilanethiolates with ZnNO2S2 and ZnN2S2 coordination pattern.
PublicationZsyntetyzowano pięć tri-tert-butoksysilanotiolanów cynku zawierających jako dodatkowe ligandy heterocykliczne, zasady azotowe. Wzór ogólny tych kompleksów to Zn(SSi(OBut)3)2L, gdzie L=alfa-pikolina, 2,4-lutydyna, N-metyloimidazol lub Zn(SSiOBut)3)2L2, gdzie L=N-metyloimidazol lub pirydyna. Określono strukturę krystaliczną otrzymanych związków oraz zmierzono widma IR i NMR.
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New examples of N^(+)-H···^(-)S hydrogen bonds: Synthesis and X-ray study of selected secondary ammonium tri-tert-butoxysilanethiolates
PublicationTri-tert-butoksysilanotiol reagując z aminami drugorzędowymi: Et2NH, morfoliną, dicykloheksyloaminą i 2,2,4,4-tetrametylopiperydyną daje odpowiednie sole amoniowe. Jak wykazują rentgenowskie badania strukturalne wszystkie te związki tworzą w ciele stałym jednostki dimeryczne {RS(-), R'NH2(+)}2, powiązane wiązaniami wodorowymi typu: N(+)-H···(-)S.
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Formation, crystal and molecular structures of heteroleptic zinc(II) tri-tert-butoxysilanethiolates with ZnNO2S2 and ZnN2S2 coordination pattern
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Investigation into MPI All-Reduce Performance in a Distributed Cluster with Consideration of Imbalanced Process Arrival Patterns
PublicationThe paper presents an evaluation of all-reduce collective MPI algorithms for an environment based on a geographically-distributed compute cluster. The testbed was split into two sites: CI TASK in Gdansk University of Technology and ICM in University of Warsaw, located about 300 km from each other, both connected by a fast optical fiber Ethernet-based 100 Gbps network (900 km part of the PIONIER backbone). Each site hosted a set...
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Variable-Fidelity Simulation Models and Sparse Gradient Updates for Cost-Efficient Optimization of Compact Antenna Input Characteristics
PublicationDesign of antennas for the Internet of Things (IoT) applications requires taking into account several performance figures, both electrical (e.g., impedance matching) and field (gain, radiation pattern), but also physical constraints, primarily concerning size limitation. Fulfillment of stringent specifications necessitates the development of topologically complex structures described by a large number of geometry parameters that...
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Unequally-Spaced Slot Strategy for Radiation Null Reduction in Single SIW-Embedded Antenna Element
PublicationThe incorporation of higher-order modes (HOMs) can substantially augment the antenna gain and bandwidth, but this improvement is typically accompanied by compromised radiation performance including radiation nulls and higher side lobe levels. In this study, an inventive strategy is introduced to reduce the radiation nulls and the side lobe levels of a single antenna element by positioning multiple slots of the radiating element...
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Error analysis of calculating average d-q current components using Regular Sampling and Park transformation in FOC drives
PublicationIn electric drives using voltage source inverters, motor currents contain ripple component resulting from pulse-width modulated (PWM) voltage. The frequency range of the ripples is much higher than the bandwidth of current control. Therefore the control is performed on the basis of a fundamental current component, i.e. average value with the averaging time being the PWM period. In majority of cases the average current is measured...
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Light box for investigation of characteristics of optoelectronics detectors
PublicationIn this paper, a light box for investigation of characteristics of optoelectronic detectors is described. The light box consists of an illumination device, an optical power sensor and a mechanical enclosure. The illumination device is based on four types of high-power light emitting diodes (LED): white light, red, green and blue. The illumination level can be varied for each LED independently by the driver and is measured by optical...
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Surrogate-Assisted Design of Checkerboard Metasurface for Broadband Radar Cross-Section Reduction
PublicationMetasurfaces have been extensively exploited in stealth applications to reduce radar cross section (RCS). They rely on the manipulation of backward scattering of electromagnetic (EM) waves into various oblique angles. However, arbitrary control of the scattering properties poses a significant challenge as a design task. Yet it is a principal requirement for making RCS reduction possible. This article introduces a surrogate-based...
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Using Fast Frequency Hopping Technique to Improve Reliability of Underwater Communication System
PublicationAcoustic underwater communication systems designed to work reliably in shallow coastal waters must overcome major limitations such as multipath propagation and the Doppler effect. These restrictions are the reason for the complexity of receivers being built, whose task is to decode a symbol on the basis of the received signal. Additional complications are caused by the low propagation speed of the acoustic wave in the water and...
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Highly Integrable Planar-structured Printed Circularly Polarized Antenna for Emerging Wideband Internet of Things Applications in the Millimeter-Wave Band
PublicationThis paper proposes a numerically and experimentally validated printed wideband antenna with a planar geometry for Internet of Things (IoT) applications. This design tackles the challenges associated with deploying IoT sensors in remote areas or across extensive geographical regions. The proposed design exploits a coplanar-waveguide-fed modified microstrip line monopole for excitation of circularly polarized waves radiating in...
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Three-dimensional Web Geographic Information System using web-based technologies
PublicationWeb-based Geographic Information Systems offer a way of delivering geographic information to devices with small computational power, such as smartphones. In recent years, the rapid development of the Web Graphics Library (WebGL) made it possible to create rich interactive applications running inside a web browser and displaying three-dimensional objects using hardware acceleration. This paper presents a three-dimensional Web-GIS...
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Low-Cost Flight Simulator with Possibility of Modeling of Flight Controls Failures
PublicationThe goal of this paper is to present a development of a low cost flight simulator, that allows to simulate flight controls failures. Cessna 172 has been chosen as an example of a general aviation aircraft and the flight model has been implemented in Simulink. The model allows for easy integration of an experimental autopilot, using various strategies. Aerodynamic coefficients have been calculated using software called DATCOM. Such...
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Stanowisko wizualizacji zdarzeń w systemie STRADAR – realizacja i funkcje dla operatora
PublicationIt is crucial for the Border Guard to be equipped with a communication-teleinformatic infrastructure designed to support them in efficient realization of their operational tasks. STRADAR – a system which results are presented in this paper – is such an infrastructure. It is a distributed solution for the maritime division of the border guard. The system, with the use of a network of sensors located in both stationary and mobile...
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A chemo-mechano-thermodynamical contact theory for adhesion, friction, and (de)bonding reactions
PublicationThis work presents a self-contained continuum formulation for coupled chemical, mechanical, and thermal contact interactions. The formulation is very general and, hence, admits arbitrary geometry, deformation, and material behavior. All model equations are derived rigorously from the balance laws of mass, momentum, energy, and entropy in the framework of irreversible thermodynamics, thus exposing all the coupling present in the...
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Zarządzanie projektami informatycznymi w jednostkach sadownictwa powszechnego w Polsce
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Four Degree-of-Freedom Hydrodynamic Maneuvering Model of a Small Azipod-Actuated Ship With Application to Onboard Decision Support Systems
PublicationThe main contribution of this paper is a numerical ship motion model of NTNU’s research vessel Gunnerus, capturing the surge, sway, roll, and yaw dynamics when sailing in uniform and steady currents. The model utilizes a crossflow drag formulation for the transverse viscous loads, and it includes a nonlinear formulation for the propulsion and steering loads provided by two azipod thrusters. A wide range of experimental data obtained...
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Dynamic fracture of brittle shells in a space-time adaptive isogeometric phase field framework
PublicationPhase field models for fracture prediction gained popularity as the formulation does not require the specification of ad-hoc criteria and no discontinuities are inserted in the body. This work focuses on dynamic crack evolution of brittle shell structures considering large deformations. The energy contributions from in-plane and out-of-plane deformations are separately split into tensile and compressive components and the resulting...