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Wyniki wyszukiwania dla: wireless mesh networks
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Mathematical modelling of implant in an operated hernia for estimation of the repair persistence
PublikacjaThis paper presents mathematical modelling of an implanted surgical mesh used in the repair process of the abdominal hernia. The synthetic implant is simulated by a membrane structure. The author provides a material modelling of the implant based on the dense net model appropriate for technical fabrics. The accuracy of the proposed solution is evaluated by comparing the simulations of the dynamic behaviour of the system with the...
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On the necessity of experimental verification of numerical results in biomedical applications
PublikacjaPorous structures made of metal or biopolymers with a structure similar in shape and mechanical properties to human bone can be easily produced by stereolitography techniques, e.g. selective laser melting (SLM). Numerical techniques, like finite element method (FEM) have great potential in testing new, even the most sophisticated designs, according to their mechanical properties, i.e. strength or stiffness. However, due to different...
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A taxonomy of challenges to resilient message dissemination in VANETs
PublikacjaInter-vehicular communications is seen as a promising solution to a number of issues related with public road safety, road congestion management, and infotainment. However, Vehicular Ad-hoc NETworks (VANETs) characterized by high mobility of vehicles and facing a number of other issues related with high frequency wireless communications and network disconnections, encounter major challenges related with reliability of message delivery....
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A PRELIMINARY STUDY ON THE OPTIMAL CHOICE OF AN IMPLANT AND ITS ORIENTATION IN VENTRAL HERNIA REPAIR
PublikacjaThis paper addresses the problem of ventral hernia repair. The main goals are to find an optimal surgical mesh for hernia repair and to define its optimal orientation in the abdominal wall to minimise the maximum force at the tissue-implant juncture. The optimal mesh is chosen from a set of orthotropic meshes with different stiffness ratios for typical hernia placement in the abdominal area. The implant is subjected to an anisotropic...
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Mechanizmy odkrywania usług i integracji międzysieciowej w samoorganizujących systemach bezprzewodowych standardu IEEEE 802.11s
PublikacjaWobec gwałtownie rosnącej popularności urządzeń mobilnych rośnie również zainteresowanie bezprzewodowymi systemami dostępowymi. Wśród nich ciekawą propozycją są systemy sieci samoorganizujących się typu mesh, których przykładem może być standard IEEE 802.11s. W artykule przedstawiono propozycje rozbudowy wybranych jego mechanizmów, w wyraźny sposób zwiększające efektywność współpracy sieci mesh z sieciami zewnętrznymi oraz rozwiązaniami...
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Dynamic coloring of graphs
PublikacjaDynamics is an inherent feature of many real life systems so it is natural to define and investigate the properties of models that reflect their dynamic nature. Dynamic graph colorings can be naturally applied in system modeling, e.g. for scheduling threads of parallel programs, time sharing in wireless networks, session scheduling in high-speed LAN's, channel assignment in WDM optical networks as well as traffic scheduling. In...
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Fluid–Structure Interaction methods for the progressive anatomical and artificial aortic valve stenosis
PublikacjaCardiovascular system diseases, as aortic valve stenosis, are the main cause of mortality and morbidity among patients. There is still a room for enhancement of the diagnostic and therapeutic procedures, which will lead to improvement of the treatment. One of the remedies are the computer tools to support the medical diagnoses and prostheses design. The development of a procedure for modeling the aortic valves: anatomical tricuspid...
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Design and Performance Evaluation of the Energy Subsystem of a Hybrid Light andWave Energy Harvester
PublikacjaThe paper presents the design and performance of an energy subsystem (ES) dedicated to hybrid energy harvesters (HEHs): wave energy converters (WECs) combined with photovoltaic panels (PVPs). The considered ES is intended for compact HEHs powering autonomous end-node devices in distributed IoT networks. The designed ES was tested experimentally and evaluated in relation to the mobile and wireless distributed communication use case....
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Towards truly sustainable IoT systems: the SUPERIOT project
PublikacjaThis paper provides an overview of the SUPERIOT project, an EU SNS JU (Smart Networks and Services Joint Undertaking) initiative focused on developing truly sustainable IoT systems. The SUPERIOT concept is based on a unique holistic approach to sustainability, proactively developing sustainable solutions considering the design, implementation, usage and disposal/reuse stages. The concept exploits radio and optical technologies...
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Impact response of novel layered two stage fibrous composite slabs with different support type
PublikacjaThe performance of novel Layered Two Stage Fibrous Composite slabs (LTSFC) was pioneered under falling mass collisions using a combined experimental and numerical study. Such LTSFC slabs consist of three layers with and without the insertion of glass fibre mesh between the layers. LTSFC techniques were used to fabricate the composite slabs with three layers including 3%, 1.5%, and 3% of fibre content for the top, middle, and...
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Mechanical behaviour of the implant used in human hernia repair under physiological loads
PublikacjaIn laparoscopic operations of abdominal hernias some recurrences still take place, even when applying a surgical mesh. This is usually caused by a failure of the connection between the tissue and the implant. The study deals with the influence of an implant’s orientation on forces in joints, which connect the mesh to human tissues. In the paper, the implant is modelled as a membrane structure within framework of the Finite Element...
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COMPARATIVE EVALUATION OF FERRITE SHIELDING DESIGNS IN INDUCTIVE POWER TRANSFER SYSTEMS
PublikacjaWireless power transfer technology is becoming widespread in last few years. In comparison to conventional solutions this technology can significantly increase maintainability and safety of charging systems. From the other side there are list of factors that limit efficiency of wireless systems. One of them is low coupling between coils caused by comparably high leakage inductance in comparison to regular transformer.
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Characteristics of the polarised off-body channel in indoor environments
PublikacjaThis paper addresses the depolarisation effect in off-body body area networks channels, based on measurements performed at 2.45 GHz in an indoor environment. Seven different scenarios, involving both static and dynamic users, were considered, taking a statistical perspective. The analysis of the cross-polarisation discrimination is performed, as well as the analysis of path loss in co- and cross-polarised channels. Results show...
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A family of new generation miniaturized impedance analyzers for technical object diagnostics
PublikacjaThe paper presents the family of three analyzers allowing to measure impedance in range of 10 ohm<|Zx|<10 Gohm in a wide frequency range from 10 mHz up to 100 kHz. The most important features of the analyzers family are: miniaturization, low power consumption, low production cost, telemetric controlling and the use of impedance measurement method based on digital signal processing DSP. The miniaturization and other above mentioned...
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Modeling a Traffic Remapping Attack Game in a Multi-hop Ad Hoc Network
PublikacjaIn multi-hop ad hoc networks, selfish nodes may unduly acquire high quality of service (QoS) by assigning higher priority to source packets and lower priority to transit packets. Such traffic remapping attacks (TRAs) are cheap to launch, impossible to prevent, hard to detect, and harmful to non-selfish nodes. While studied mostly in single-hop wireless network settings, TRAs have resisted analysis in multi-hop settings. In this paper...
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Direction-of-Arrival Estimation Using an ESPAR Antenna with Simplified Beam Steering
PublikacjaIn this paper, it has been shown, how electronically steerable parasitic array radiator (ESPAR) antenna, in which beam steering is done in a simple way, can be used for directionof- arrival (DoA) estimation of an unknown signal impinging the antenna. The concept is based on an ESPAR antenna having twelve parasitic elements, in which beam switching is realized by RF switches providing required loads to its parasitic elements. Numerical...
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Variable‐fidelity modeling of antenna input characteristics using domain confinement and two‐stage Gaussian process regression surrogates
PublikacjaThe major bottleneck of electromagnetic (EM)-driven antenna design is the high CPU cost of massive simulations required by parametric optimization, uncertainty quantification, or robust design procedures. Fast surrogate models may be employed to mitigate this issue to a certain extent. Unfortunately, the curse of dimensionality is a serious limiting factor, hindering the construction of conventional data-driven models valid over...
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Smooth Particle Hydrodynamics (SPH) approach in simulating large penetration into soil
PublikacjaA study of Smooth Particle Hydrodynamics (SPH) approach for predicting large soil deformation is presented. Theoretical basics of SPH method, including the equations governing, discussion of the importance of smoothing function length, contact formulation, boundary treatment and finally utilization in hydrocodes simulations are presented. An application of SPH to a real case of large penetrations (crater creating) into soil caused...
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Collision‐Aware Routing Using Multi‐Objective Seagull Optimization Algorithm for WSN‐Based IoT
PublikacjaIn recent trends, wireless sensor networks (WSNs) have become popular because of their cost, simple structure, reliability, and developments in the communication field. The Internet of Things (IoT) refers to the interconnection of everyday objects and sharing of information through the Internet. Congestion in networks leads to transmission delays and packet loss and causes wastage of time and energy on recovery. The routing protocols...
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Feasibility Study GaN Transistors Application in the Novel Split-Coils Inductive Power Transfer System with T-Type Inverter
PublikacjaA promising solution for inductive power transfer and wireless charging is presented on the basis of a single-phase three-level T-type Neutral Point Clamped GaN-based inverter with two coupled transmitting coils. The article focuses on the feasibility study of GaN transistor application in the wireless power transfer system based on the T-type inverter on the primary side. An analysis of power losses in the main components of the...
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Cost-Effective and Sufficiently Precise Integration Method Adapted to the FEM Calculations of Bone Tissue
PublikacjaThe technique of Young’s modulus variation in the finite element is not spread in biomechanics. Our future goal is to adapt this technique to bone tissue strength calculations. The aim of this paper is to present the necessary studies of the element’s integration method that takes into account changes in material properties. For research purposes, a virtual sample with the size and distribution of mechanical properties similar...
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Global Complex Roots and Poles Finding Algorithm Based on Phase Analysis for Propagation and Radiation Problems
PublikacjaA flexible and effective algorithm for complex roots and poles finding is presented. A wide class of analytic functions can be analyzed, and any arbitrarily shaped search region can be considered. The method is very simple and intuitive. It is based on sampling a function at the nodes of a regular mesh, and on the analysis of the function phase. As a result, a set of candidate regions is created and then the roots/poles are verified...
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Modelowanie losowych imperfekcji geometrycznych przestrzennych konstrukcji metalowych
PublikacjaImperfekcje geometryczne zbiorników, silosów i powłok siatkowych mogą znaczą-co wpłynąć na ich nośność, a więc powinny być one uwzględniane w obliczeniach komputerowych i w procesie projektowania. Wykazano, że przy podstawowych obcią-żeniach, działających na tego typu konstrukcje, tj. podciśnieniu oraz naporu wiatru i śniegu (w przypadku powłok siatkowych), wykazują wyraźne różnice w porównaniu z analogicznymi wynikami dla tych...
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Creation of Hydrogen Bonded 1D Networks by Cocrystallization of N,N`-bis(2-pyridyl) aryldiamines with Dicarboxylic Acids.Tworzenie 1D sieci krystalicznych poprzez kokrystalizację N,N` -bis(2-piry- dylo) arylodiamin z kwasami dikarboksylowymi.
PublikacjaZsyntetyzowano szereg N,N`-bis(2-pirydylo) arylodiamin, a następnie otrzymano serię kompleksów w/w amin z kwasami dikarboksylowymi oraz kwasem kwadratowym w postaci monokryształów. Jednostki N,N`-bis(2-pirydylo) arylodiamin i kwasy dikarboksylowe oddziaływują ze sobą poprzez wiązania wodorowe tworząc ośmioczłonowy cykliczny układ. W kompleksach 1:1 cząsteczki układają się w jedno-wymiarową sieć krystaliczną tworzoną przy udziale...
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Cellular network quality evaluation at a university campus on the eve of 5G
PublikacjaThanks to the availability of mobile devices and the spread of broadband access around the world, the number of network users continues to grow. This has raised user awareness when it comes to the quality of content they consume. Many service providers and operators focus on monitoring QoN (Quality of Network) and QoS (Quality of Service) parameters, particularly those influenced by bandwidth and latency. However, for most end-users,...
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Behaviour of orthotropic surgical implant in hernia repair due to the material orientation and abdomen surface deformation
Publikacjarelation to the different range of typical deformations observed in different directions and zones of abdomen surface due to the patients’ life activities, has a significant influence on the extreme junction forces in the mesh–tissue connections and hence the repair persistence. The finite element model of the orthotropic implant was developed, and the junction forces in the connections of tissue and mesh were studied. The kinematical...
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Geometry Parametric Model Order Reduction with Randomly Generated Projection Bases
PublikacjaIn this work, a reduced-order model for geometry parameters and fast frequency sweep is proposed. The Finite Element Method is used to solve time-harmonic Maxwell’s equations. Taking into account the electromagnetic field does not arbitrarily vary as a function of frequency and geometry parameters, a low dimension system manifold is identified. Thus, the original Finite Element problem can be approximated by a model of reduced...
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Wirelessly Interfacing Objects and Subjects of Healthcare System – IoT Approach
PublikacjaWireless sensor networks, WSN, for which development has begun by military applications, are nowadays applied to all human activities; e.g. in medicine for patience monitoring or to reduce the effects of disasters. Therefore, the WSNs area has been also one of the emerging and fast growing scientific fields. Increasing interest of WSNs is even caused by equally intense growth of interest in the Internet of Things domain, IoT, in...
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Physical and mathematical modelling of implant-fascia system in order to improve laparoscopic repair of ventral hernia
PublikacjaThis paper describes an investigation of biomechanical behaviour of hernia repair, which is focused on the selection of safe linking of certain type of implant with fascia in laparoscopic operation. The strength of various fixations of the implant to the fascia is analysed. Methods: The research is based on experimental observations of operated hernia model behaviour during a dynamic impulse load corresponding to post-operative...
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Safety and efficacy of a Ventralight ST echo ps implant for a laparoscopic ventral hernia repair – a prospective cohort study with a one-year follow-up
Publikacjaing new products Thus, every mesh prior to introduction in clinical settings should be tested with a dedicated tacker to discover the proper fixation algorithm. The aim of the study was to assess the safety and efficacy of the Ventralight ST implant with an ECHO positioning system and a dedicated fixation device, the SorbaFix stapler, in a prospective cohort of patients. Material and methods. The study was a prospective single...
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Pilotażowa instalacja sieci bezprzewodowej bezprzewodowej standardu WiMax na Politechnice Gdańskiej
PublikacjaRozdział przedstawia analizę teoretyczną oraz opis pilotażowego wdrożenia standardu IEEE 802.11 (WiMAX) na Politechnice Gdańskiej. Przedstawiono unikalną funkcjonalność oferowaną przez technologię WiMAX według ustaleń standaryzacyjnych oraz realizowaną na dostępnych w tej chwili na rynku urządzeniach, a także możliwe scenariusze zastosowania tego rodzaju systemów
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Multi-objective design of miniaturized impedance transformers by domain segmentation
PublikacjaFast multi-objective design optimization of compact microstrip impedance transformers is discussed. Our approach exploits approximation models constructed using sampled coarse- mesh EM simulation data in a partitioned design space and response correction techniques for design refinement. Demonstra
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Research into flows in turbine blade seals. Part II: Numerical analysis
PublikacjaPrzedstawiono wyniki badań numerycznych programem Fluent przepływów w uszczelnieniu nadbandażowym stopnia turbinowego. Badania wykonano przy zastosowaniu różnych typów siatek obliczeniowych, różnych rodzajów "zszywek" oraz różnych metod obliczeniowych (Mixing Plane, Sliding Mesh, Multiple ReferenceFrame).
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Structures for parameterization, meshing and data exchange of topologically related surfaces of a ship hull
PublikacjaThis paper presents proposal of data structures for storage and processing of a parametric three-dimensional model of a midship hull sections. The model consists of coarse surfaces like: decks, frames, girders, stiffeners, brackets, partitions etc. bounded by topological relations. All workshop details are omitted as the model is intended for numeric calculations. Proposed data structures are prepared to facilitate changes in the...
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Orthotropic membrane as a mechanical model of surgical implant in abdominal hernia repair
PublikacjaEven though the incisional hernia repair surgery is a well known procedure, mechanical properties of the tissue-implant system are unknown so the implantation of the repairing mesh is quite intuitive and, recurrences of the illness still take place. The main objective of the study is to define an operated hernia model that can be used for surgery planning and the assessment of the repair persistence. The load applied to the structure...
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Comparing Apples and Oranges: A Mobile User Experience Study of iOS and Android Consumer Devices
PublikacjaWith the rapid development of wireless networks and the spread of broadband access around the world, the number of active mobile user devices continues to grow. Each year more and more terminals are released on the market, with the smartphone being the most popular among them. They include low-end, mid-range, and of course high-end devices, with top hardware specifications. They do vary in build quality, utilized type of material,...
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Biomechanical causes for failure of the Physiomesh/Securestrap system
PublikacjaThis study investigates the mechanical behavior of the Physiomesh/Securestrap system, a hernia repair system used for IPOM procedures associated with high failure rates. The study involved conducting mechanical experiments and numerical simulations to investigate the mechanical behavior of the Physiomesh/Securestrap system under pressure load. Uniaxial tension tests were conducted to determine the elasticity modulus of the Physiomesh...
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Virtual spring damper method for nonholonomic robotic swarm self-organization and leader following
PublikacjaIn this paper, we demonstrate a method for self-organization and leader following of nonholonomic robotic swarm based on spring damper mesh. By self-organization of swarm robots we mean the emergence of order in a swarm as the result of interactions among the single robots. In other words the self-organization of swarm robots mimics some natural behavior of social animals like ants among others. The dynamics of two-wheel robot...
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IoT protocols, architectures, and applications
PublikacjaThe proliferation of embedded systems, wireless technologies, and Internet protocols have enabled the IoT to bridge the gap between the virtual and physical world enabling the monitoring and control of the environment by data processing systems. IoT refers to the inter-networking of everyday objects that are equipped with sensing, computation, and communication capabilities. These networks can collaboratively interact and perform...
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Impact of R/X ratio of distribution network on selection and control of energy storage units
PublikacjaThe interest in energy storage is still increasing. Energy storage units are installed in high voltage networks, medium voltage networks and low voltage distribution networks as well. These units are often used to improve power quality. One of the criteria for improving power quality is reducing voltage deviations. Depending on the type of network and specifying its R/X ratio, this criterion can be fulfilled by control of active...
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Multiscale model for blood flow after a bileaflet artificial aortic valve implantation
PublikacjaCardiovascular diseases are the leading cause of mortality in the world, mainly due to atherosclerosis and its consequences. The article presents the numerical model of the blood flow through artificial aortic valve. The overset mesh approach was applied to simulate the valve leaflets motion and to realize the moving mesh, in the aortic arch and the main branches of cardiovascular system. To capture the cardiac system’s response...
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Validation of a virtual test environment for C2X communication under radio jamming conditions
PublikacjaIn this paper, we propose a novel car-2-x communication security testing methodology in the physical layer of wireless systems. The approach is dedicated to automated testing of autonomous vehicles and it is essential for such complex systems operation, especially with regard to safety and security issues. It is based on scenario-driven testing in virtual and real test environments created from collected or simulated data. The...
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Reconfigurable Antennas for Trustable Things
PublikacjaIn modern applications, the Internet of Things plays a significant role in increasing the productivity, effectiveness or safety and security of people and assets. Additionally, the reliability of Internet of Things components is crucial from the application point of view, where a resilient and low-latency network is needed. This can be achieved by utilizing reconfigurable antennas to enhance the capabilities of the wireless sensor...
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Modelling of Geared Multi-Rotor System
PublikacjaIn the paper the method of modelling a speed-varying geared rotor system is presented. The proposed approach enables us to obtain an accurate low-order lumped parameter representation of the investigated system. The final model consists of reduced modal models of an undamped beam/torsional shaft system as well as a spatially lumped model of other linear and nonlinear phenomena including gear mesh interaction.
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Prognostic and diagnostic capabilities of OOBN in assessing investment risk of complex construction projects
PublikacjaModelling decision problems using Bayesian networks is extremely valuable especially in case of issues related to uncertainty; it is also very helpful in constructing and understanding visual representation of the elements and their relations. This approach facilitates subsequent application of Bayesian networks, however there can be situations where using simple Bayesian networks is impractical or even ineffective. The aim of...
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Open extensive IoT research and measurement infrastructure for remote collection and automatic analysis of environmental data.
PublikacjaInternet of Things devices that send small amounts of data do not need high bit rates as it is the range that is more crucial for them. The use of popular, unlicensed 2.4 GHz and 5 GHz bands is fairly legally enforced (transmission power above power limits cannot be increased). In addition, waves of this length are very diffiult to propagate under field conditions (e.g. in urban areas). The market response to these needs are the...
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Example of Using Particle Swarm Optimization Algorithm with Nelder–Mead Method for Flow Improvement in Axial Last Stage of Gas–Steam Turbine
PublikacjaThis article focuses principally on the comparison baseline and the optimized flow efficiency of the final stage of an axial turbine operating on a gas–steam mixture by applying a hybrid Nelder– Mead and the particle swarm optimization method. Optimization algorithms are combined with CFD calculations to determine the flowpaths and thermodynamic parameters. The working fluid in this study is a mixture of steam and gas produced...
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Methodology of generation of CFD meshes and 4D shape reconstruction of coronary arteries from patient-specific dynamic CT
PublikacjaDue to the difficulties in retrieving both the time‑dependent shapes of the vessels and the generation of numerical meshes for such cases, most of the simulations of blood flow in the cardiac arteries use static geometry. The article describes a methodology for generating a sequence of time‑dependent 3D shapes based on images of different resolutions and qualities acquired from ECG‑gated coronary artery CT angiography. The precision...
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A Test-Bed Analysis of Simultaneous PMIPv6 Handover in 802.11 WLANs Environment
PublikacjaProviding mobility in access networks is a challenge that we have to deal with. Due to networks’ convergence and migration to all-IP networks, mobility management at the network layer is required. However, there is a need for cooperation mechanisms between the network layer and lower layers to support multimedia services and make handover more efficient. This paper presents experimental research on simultaneous handover performance...
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Comparative Evaluation of Multicoil Inductive Power Transfer Approaches Based on Z-source Network
PublikacjaThis paper describes comparative evaluation between wireless power transfer topologies with utilization of Z-source network. Paper describes components calculation method. List of open-loop, close-loop simulations were conducted to compare both topologies. Spectrum of signals is also researched.