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Search results for: OPEN CHANNEL FLOW
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Using FreeFEM open software for modelling the vibrations of piezoelectric devices
PublicationModelling vibrations of piezoelectric transducers has been a topic discussed in the literature for many decades. The first models - so-called one-dimensional - describe the vibrations only near operating frequency and near its harmonics. Attempts to introduce two-dimensional models were related to the possibility of one transducer working at several frequencies, including both thickness vibrations and those resulting from the transducer...
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Selected local stability problems of channel section flanges made of aluminium alloys
PublicationThe paper addresses the issue of local buckling of compressed flanges of cold-formed thin-walled channel columns and beams with nonstandard flanges composed of aluminium alloys. The material behaviour follows the Ramberg–Osgood law. It should be noted that the proposed solution may be also applied for other materials, for example: stainless steel, carbon steel. The paper is motivated by an increasing interest in nonstandard cold-formed...
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Flow boiling intensification in minichannels by means of mechanical flow turbulising inserts
PublicationThe work presents the results of experimental investigation on heat transfer in minichannels. Refrigerant R123 was used as a test fluid. Single vertical silver tubes of 380 mm length and 2.3 mm diameter were examined with two variants of turbulising inserts. A wide range of parameters was considered, namely mass flux G=534-3011 kg/(m2s), heat flux qw=28.5-68.4 kW/m2, saturation temperature Tsat=23-86 stC and the full range of vapour...
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Experimental Verification of Storm Sewer Transient Flow Simulation
PublicationThe paper focuses mainly on laboratory investigations of transient and transcritical flow in a single pipe of a sewer system. The aim of this paper is to present a comparison between pressure values calculated by an improved McCormack scheme and those measured at the hydraulic laboratory of the Gdansk University of Technology, which were observed inside a pipe in an experiment for water flow with pressurization. The analysis proves...
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QoS Extensions for Flow-Awareness Networks
PublicationThe paper contains a description and research results of the proposal for distributed QoS extensions for Flow-Based Networking. These QoS extensions let the network accept or reject flows based on current network load and QoS promises for each of the flows. Proposed solution consists of two distributed components, each of them performing in every node, measurement system and access control. The solution could be applied in any...
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Evaluation of propagation parameters of open guiding structures with the use of complex root finding algorithms
PublicationAn efficient complex root tracing algorithm is utilized for the investigation of electromagnetic wave propagation in open guiding structures. The dispersion characteristics of propagated and leaky waves are calculated for a couple of chosen waveguides. The efficiency of the root tracing algorithm is discuses and compared to a global root finding algorithm.
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Data librarian and data steward – new tasks and responsibilities of academic libraries in the context of Open Research Data implementation in Poland
PublicationThesis/Objective – The policy of Open Access (OA) for researching resources in Europe has been implemented for more than 10 years. The first recommendations concerning providing OA to scientific materials were defined during the implementation of the 7th Framework Programme. Introducing another set of recommendations concerning OA to research data was the next stage. The recommendations were transformed into obligations under the...
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Ammonia amendment promotes high rate lactate production and recovery from semi-continuous food waste fermentation
PublicationIn this study, a reliable approach using ammonia nitrogen was proposed to increase lactate production during semi-continuous food waste (FW) fermentation under mesophilic conditions. Both free ammonia nitrogen (FAN) and ammonium ion (NH4+-N) were present in mesophilic reactors, with a wide FAN/NH4+-N ratio variation due to the intermittent pH control. The investigation of responsible mechanisms revealed that the increased production...
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Load carrying capacity of the eccentric joint in the truss made of open cross-sections
PublicationThe influence of eccentricity at intersections of truss members on the load carrying capacity of the truss joint is presented in the paper. The research truss elements were designed as cold-formed open cross section. Analytical calculations, numerical analysis and experimental research were conducted to reveal how the eccentricity affects the effort of material in the joint area. The results of analysis and investigations are compared...
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Sensing Direction of Human Motion Using Single-Input-Single-Output (SISO) Channel Model and Neural Networks
PublicationObject detection Through-the-Walls enables localization and identification of hidden objects behind the walls. While numerous studies have exploited Channel State Information of Multiple Input Multiple Output (MIMO) WiFi and radar devices in association with Artificial Intelligence based algorithms (AI) to detect and localize objects behind walls, this study proposes a novel non-invasive Through-the-Walls human motion direction...
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Safety of Single-Channel Railway Traffic Control
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Transmission of digital signals in a nonstationary hydroacoustic channel.
PublicationZ telekomunikacyjnego punktu widzenia właściwości transmisyjne kanału hydroakustyczny są ograniczone przez występowanie wielokrotnych odbić fali dźwiękowej od dna i powierzchni wody oraz niestacjonarność wprowadzaną głównie przez ruch powierzchni wody. Artykuł przedstawia model własności transmisyjnych kanału. Wprowadzono niestacjonarność do odpowiedzi impulsowych kanału przez założenie przypadkowej zmienności czasów przyjścia...
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The selected hydrotechnical conditions of the Dnieper – Bug Channel and the Pripyat River in the development of the International Waterway E40
PublicationInternational waterway E40 (MDW E40) is included in the network of inland waterways of transnational importance. It is a link between two areas: the Baltic Sea and the Black Sea. E40 route runs through three countries: Poland, Belarus and Ukraine. The article presents the results of the study on the analysis of two very important sections of the MDW E40 on the Belarusian section, it is:. the Dnieper – Bug Channel and the Pripy...
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Pawlak's flow graph extensions for video surveillance systems
PublicationThe idea of the Pawlak's flow graphs is applicable to many problems in various fields related to decision algorithms or data mining. The flow graphs can be used also in the video surveillance systems. Especially in distributed multi-camera systems which are problematic to be handled by human operators because of their limited perception. In such systems automated video analysis needs to be implemented. Important part of this analysis...
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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...
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The Bridge of Knowledge – defining and implementing national Open Access policy by Polish universities. Gdansk University of Technology perspective
PublicationThe European Commission states that Open Access to scientific resources funded by the European Union shall facilitate the use of research results financed from the public funds. Moreover, it will cause an increase in the innovative capacity of Europe. The Open Access landscape is determined by several factors such as mandates. The open mandate may be voluntary or mandatory and implemented at the institutional, national or international...
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Comparative study of flow condensation in conventional and small diameter tubes
PublicationFlow boiling and flow condensation are often regarded as two opposite or symetrical phenomena. Their description however with a single correlation has yet to be suggested.In the case of flow boiling in minichannels there is mostly encountered the annular flow structure, where the buble generetion is not present. Similar picture holds for the case of inside tube condensation, where annular flow structure predominates. In such case...
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Flow maldistribution and its mitigation in mini heat exchangers
PublicationIn the present paper, a detailed numerical investigation has been carried out to analyze the flow maldistribution in 50 parallel 1 mm x 1 mm rectangular minichannels and 1 mm depth minigap section with rectangular, trapezoidal, triangular or concave mani-folds in Z-type flow configuration (16 different cases). The working medium was ethanol and the mass flow rate was 5×10-4 kg/s. Both sections was heated from the bottom side. Heat...
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Wzory kreatywności. Koncepcja modelu prawdopodobieństwa działania kreatywnego jako narzędzie badania procesu twórczego w środowisku miejskim
PublicationWspółczesne koncepcje kształtowania miast, takie jak zrównoważony rozwój, miasto odporne, inteligentne miasto, miasto kreatywne, tworzą obecnie ramy urbanistyki o charakterze jednej uogólnionej idei kształtującej środowisko społeczno-materialne. Kontekstualne ujęcie badań kreatywności opisuje zależności między środowiskiem miejskim a twórczością w mieście kreatywnym. Ujęcie procesualne kreatywności stanowi hic et nunc urbanizmu,...
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CFD Simulations and Tests of a Prototype Flow Control Valve
PublicationIn this paper a prototype of a flow control valve is described and numerically simulated. The flow control valve is used in hydraulic systems to maintain constant fluid flow despite changing loads of a receiver. The standard construction of this type of valves is modified mainly by eliminating the spring. The prototype consists the hydrostatically unloaded throttle valve and pressure ratio valve substituting pressure difference...
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thestats: An Open-Data R Package for Exploring Turkish Higher Education Statistics
PublicationThere are open datasets available for official statistics, finance, education, and a variety of other domains. The open datasets are published by third-party vendors as well as official authorities. For example, The Turkish Higher Education Council maintains a web portal dedicated to higher education in Türkiye. Detailed datasets about universities, faculties, and departments can be obtained from the portal. Using the data provided...
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Researching Digital Society: Using Data-Mining to Identify Relevant Themes from an Open Access Journal
PublicationOpen Access scholarly literature is scientific output free from economic barriers and copyright restrictions. Using a case study approach, data mining methods and qualitative analysis, the scholarly output and the meta-data of the Open Access eJournal of e-Democracy and Open Government during the time interval 2009–2020 was analysed. Our study was able to identify the most prominent research topics (defined as thematic clusters)...
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Researching Digital Society: Using Data-Mining to Identify Relevant Themes from an Open Access Journal
PublicationOpen Access scholarly literature is scientific output free from economic barriers and copyright restrictions. Using a case study approach, data mining methods and qualitative analysis, the scholarly output and the meta-data of the Open Access eJournal of e-Democracy and Open Government during the time interval 2009–2020 was analysed. Our study was able to identify the most prominent research topics (defined as thematic clusters)...
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The equivariant spectral flow and bifurcation of periodic solutions of Hamiltonian systems
PublicationWe define a spectral flow for paths of selfadjoint Fredholm operators that are equivariant under the orthogonal action of a compact Lie group as an element of the representation ring of the latter. This G-equivariant spectral flow shares all common properties of the integer valued classical spectral flow, and it can be non-trivial even if the classical spectral flow vanishes. Our main theorem uses the G-equivariant spectral flow...
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(Re)Shaping Open Access Policy to Scientific Resources at Polish Technical Universities: Gdańsk University of Technology Perspective
PublicationDeveloping European Open Access policy to scientific resources is one of the most important issues undertaken during the public debate about future scholarly communication trends. The Open Access landscape is determined by several factors (e.g. mandates). The open mandate: voluntary or mandatory, can be implemented at the institutional, national or international level. It requires scholars to use open repository to deposit results...
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Flow of liquid in flat gaps of the satellite motor working mechanism
PublicationThe article describes the methodology and results of investigations of the flow of oil and HFA-E emulsion in flat gaps of the working mechanism of a satellite motor. The flow of liquid in those gaps is turbulent and not fully developed. The article presents two methods of modelling this flow. Method I makes use of the Darcy-Weisbach formula, while Method II bases on the assumption that in the variable-length gaps the flow is turbulent...
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Open-transistor fault diagnostics in voltage-source inverters by analyzing the load current
PublicationA novel method is presented for the detection andisolation of open-transistor faults in voltage-source invertersfeeding low-power AC motors. The method is based onmonitoring two diagnostic signals, one indicating sustained nearzerovalues of output current and thus permitting fault detection,the other permitting the isolation of the particular transistorwhich went faulty. The latter signal is the ratio of the averagephase current...
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Modeling lubricant flow between thrust-bearing pads
PublicationInlet temperature is one of the main inputs in all models for the analysis of fluid film bearing performance. At the same time, inlettemperature distribution and also oil velocity distribution at the inlet are the result of flow phenomena in the gap between the bearingpads. These phenomena are complex and in many cases further affected by any special arrangements of forced oil supply to the gapbetween pads. The reason for such...
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Influence of the air phase on water flow in dikes
PublicationNumerical models are often used to describe flow and deformation processes occurring in dikes during flood events. Modeling of such phenomena is a challenging task, due to the complexity of the system, consisting of three material phases: soil skeleton, pore water and pore air. Additional difficulties are transient loading caused by variable in time water levels, heterogeneity of the soil or air...
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Evaluation of Open Source SIEM for Situation Awareness Platform in the Smart Grid Environment
PublicationThe smart grid as a large-scale system of systems has an exceptionally large surface exposed to cyber-attacks, including highly evolved and sophisticated threats such as Advanced Persistent Threats (APT) or Botnets. When addressing this situation the usual cyber security technologies are prerequisite, but not sufficient. The smart grid requires developing and deploying an extensive ICT infrastructure that supports significantly...
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Activation Energy and Inclination Magnetic Dipole Influences on Carreau Nanofluid Flowing via Cylindrical Channel with an Infinite Shearing Rate
PublicationThe infinite shear viscosity model of Carreau fluid characterizes the attitude of fluid flow at a very high/very low shear rate. This model has the capacity for interpretation of fluid at both extreme levels, and an inclined magnetic dipole in fluid mechanics has its valuable applications such as magnetic drug engineering, cold treatments to destroy tumors, drug targeting, bio preservation, cryosurgery, astrophysics, reaction kinetics,...
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Selected studies of flow maldistribution in a minichannel plate heat exchanger
PublicationAnalysis of the state of-the-art in research of minichannel heat exchangers, especially on the topic of flow maldistribution in multiple channels, has been accomplished. Studies on minichannel plate heat exchanger with 51 parallel minichannels with four hydraulic diameters, i.e., 461 μm, 574 μm, 667 μm, and 750 μm have been presented. Flow at the instance of filling the microchannel with water at low flow rates has been visualized. The...
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Torsion of restrained thin-walled bars of open constant bisymmetric cross-section
PublicationElastic and geometric stiffness matrices were derived using Castigliano's first theorem, for the case of torsion of restrained thin-walled bars of open constant bisymmetric cross-section. Functions which describe the angles of torsion were adopted from the solutions of thedifferential equation for restrained torsion. The exact solutions were simplified by expanding them in a power series. Numerical examples were taken from Kujawa...
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Koala graph coloring library: an open graph coloring library for real-world applications
PublicationPomimo intensywnej pracy naukowej na polu kolorowania grafów, nie jest znana kompletna i dedykowana biblioteka programistyczna. Celem artykułu jest zaproponowanie architektury takiej biblioteki. Celem jest spełnienie oczekiwań wypływających z rzeczywistych zastosowań, w szczególności spełnienie potrzeb wydajnościowych. Zaimplementowano szereg algorytmów cheurystycznego kolorowania grafów. Przyjętym językiem programowania jest C++....
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Ciemna strona Open Access - naukowcy w szponach drapieżnych wydawców
PublicationRuch Open Access (OA), czyli inicjatywa mająca na celu upowszechnienie otwartego modelu komunikacji naukowej, z roku na rok zyskuje zwolenników. Obok znanych i cenionych firm, które poprzez swoją politykę wydawniczą wspierają ruch OA, powstały też takie, które w swej działalności stosują nieprofesjonalne, nieetyczne i krzywdzące publikujących, a często zakazane przez prawo praktyki. Referat ma na celu przybliżenie działań nieuczciwych...
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The logistics streamlining of the material flow at the production company
PublicationThe main practical problem in the Logistics Department at the company is overstaffing in the unit responsible for the flow of materials. Carried out by the authors of the article, some detailed research on the process analysis in the discussed company indicates that the main cause of such a situation is related to an increase in the amount of transported material and a lack of redesigning the material flow in...
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Propagation in the Open Cylindrical Guide of Arbitrary Cross Section With the Use of Field Matching Method
PublicationA simple solution to propagation problem in open waveguides and dielectric fibers of arbitrary convex cross section is presented. The idea of the analysis is based on the direct field matching technique involving the usage of the field projection at the boundary on a fixed set of orthogonal basis functions. A complex root tracing algorithm is utilized to find the propagation coefficients of the investigated guides. Different convex...
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Accessibility of the Open Public Space in Cities
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Public Space Projects in the Open Areas
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Chromatic scheduling in a cyclic open shop
PublicationPraca jest poświęcona złożoności obliczeniowej problemu cyklicznego szeregowania w systemie otwartym. Autorzy analizując wykazują, że problem jest NP-trudny dla 3 procesorów i konstruują algorytm dokładny dla przypadku dwóch procesorów.Ponadto analizowany jest zwarty wariant cyklicznego systemu otwartego. W tym przypadku autorzy pokazują, że już szeregowanie na dwóch procesorach prowadzi do problemu NP-trudnego.
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Migration Integrity Rules in Open Systems
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Comparative study of flow condensation in conventional and small diameter tubes
PublicationFlow boiling and flow condensation are often regarded as two opposite or symmetrical phenomena, however their description with a single correlation has yet to be suggested. In the case of flow boiling in minichannels there is mostly encountered the annular flow structure, where the bubble generation is not present. Similar picture holds for the case of inside tube condensation, where annular flow structure predominates. In such...
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Efficient Fabry-Perot Open Resonator Analysis by the use of a Scattering Matrix Method
PublicationIn this paper a comparative study of the computational efficiency of two modeling methods applied to the analysis of the plano- and double-concave Fabry-Perot open resonators is presented. In both numerical approaches, a scattering matrix method was applied, which allows splitting the analysis of the resonator into several sections, including the one with a spherical mirror, which requires the largest computing resources. Two modeling...
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Realizacja systemu zarządzania wydziałem wyższej uczelni w technologiach typu open-source
PublicationW artykule przedstawiono założenia projektowe, architekturę i implementację systemu przeznaczonego do wspomagania zarządzania wydziałem wyższej uczelni. System jest realizowany dla Wydziału Elektroniki, Telekomunikacji i Informatyki Politechniki Gdańskiej, w technologiach typu open-source. Artykuł opisuje poszczególne komponenty systemu oraz aspekty technologiczne jego budowy. Opisano założenia przyjęte na początku projektu, architekturę...
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Recent progress in experimental studies of electrohydrodynamic flow in electrostatic precipitators
PublicationMany experimental, theoretical and numerical works were devoted to the electrohydrodynamic (EHD) flow generated in electrostatic precipitators (EPSs). The generally accepted conclusion from these studies is that the EHD flow plays an important role in the particle collection in ESPs. However, despite of the recent fast progress in numerical simulation and experimental techniques used in the ESPs studies many problems related to...
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Impact of information systems (IS) infusion on Open Government Data (OGD) adoption
PublicationPurpose – This study aims to underline the possible influence of the moderator, information systems (IS) infusion, on Open Government Data (OGD) adoption and usage. Design/methodology/approach – Using the partial least squares-structural equation modeling methodological approach, the adapted unified theory of acceptance and use of technology (UTAUT) model has been used for understanding the role of themoderating variable, namely,...
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Evaluation of the significance of the effect of the active cross-sectional area of the inlet air channel on the specific enthalpy of the exhaust gas of a diesel engine using statistics F of the Fisher-Snedecor distribution
PublicationThis paper presents the application of Fisher-Snedecor distribution F statistics to assess the significance of the influence of changes in the active cross-sectional area of the inlet air channel (Adol) flow in a diesel engine on the observed diagnostic parameter determined on the basis of measurements of the quick changing exhaust gas temperature in the outlet channel, which is the specific enthalpy of the exhaust gas stream within...
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Investigations on mixture preparation for two phase adiabatic pressure drop of R134a flowing in 5 mm diameter channel
PublicationThe article presents detailed two-phase adiabatic pressure drops data for refrigerant R134a. Study cases have been set for a mass flux varying from 200 to 400 kg/m2 s, at the saturation temperature of 19.4 ◦C. Obtained experimental data was compared with the available correlations from the literature for the frictional pressure drop during adiabatic flow. Influence of mixture preparation on pressure drop was investigated, for...
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Numerical solutions for blood flow in elastic vessels
PublicationWe consider the differential–algebraic system for the blood flow and pressure in the systemic arteries. By the operator splitting method, we transform the system into the hyperbolic one, introduce the bicharacteristics, and perform the time–space nonuniform discretization, obtaining the innovative difference scheme. Our results are illustrated with numerical experiments.
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Two-phase flow structure assessment based on dynamic image analysis
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