Artykuły w czasopismach: „GEOMATERIAL SUBJECT”

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Kim, Minkwan, i Joo Hyoung Lee. "STUDY ON NONLINEAR PAVEMENT RESPONSES OF LOW VOLUME ROADWAYS SUBJECT TO MULTIPLE WHEEL LOADS / NETIESINĖS KELIO DANGOS PRIKLAUSOMYBĖS NUO MAŽO INTENSYVUMO KELIŲ, VEIKIAMŲ DAUGKARTINĖMIS RATŲ APKROVOMIS, TYRIMAS". Journal of Civil Engineering and Management 17, nr 1 (13.04.2011): 45–54. http://dx.doi.org/10.3846/13923730.2011.554012.

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This paper describes numerical analyses on low volume roads (LVRs) using a nonlinear three-dimensional (3D) finite element model (FEM). Various pavement scenarios are analyzed to investigate the effects of pavement layer thicknesses, traffic loads, and material properties on pavement responses, such as surface deflection and subgrade strain. Each scenario incorporates a different combination of wheel/axle configurations and pavement geomaterial properties to analyze the nonlinear behavior of thinly surfaced asphalt pavement. In this numerical study, nonlinear stress-dependent models are employed in the base and subgrade layers to properly characterize pavement geomaterial behavior. Finite element analysis results are then described in terms of the effects of the asphalt pavement thickness, wheel/axle configurations, and geomaterial properties on critical pavement responses. Conclusions are drawn by the comparison of the nonlinear pavement responses in the base and subgrade in association with the effects of multiple wheel/axle load interactions. Santrauka Straipsnyje aprašoma skaitinė mažo intensyvumo kelių analizė, taikant netiesinį—erdvinį baigtinių elementų modelį. Skirtingi dangų paviršiaus variantai analizuojami siekiant ištirti, kokiąįtaką kelio dangos elgsenai, t. y. poslinkiams ir kelio pagrindo deformacijoms, turi dangų sluoksnių storiai, eismo apkrovos ir medžiagų savybės. Kiekvienas kelio dangos variantas turi skirtingas ratų arba ašies ir geometrinių savybių formas, kad būtų galima išanalizuoti netiesinę plonos asfalto dangos paviršiaus elgseną. Šioje skaitinėje analizėje nagrinėjami netiesiniai įtempių modeliai, kurie buvo taikomi pagrindo sluoksniams, siekiant tinkamai apibūdinti geometrinę kelio dangos elgseną. Baigtinių elementų analizės rezultatai toliau nagrinėjami atsižvelgiant į asfalto dangos storį ar ašies formą ir geometrines savybes, priklausomai nuo kritinės kelio dangos būklės. Išvados buvo gautos lyginant netiesines kelių dangos priklausomybes pagrindo sluoksnyje, atsižvelgiant į jų sąveiką su daugkartine ratų apkrova.

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Bista, Hemanta, Sadrish Panthi i Liangbo Hu. "Chemo-Mechanical Couplings at Granular Contact: The Effect of Mineral Dissolution and Precipitation across the Scales". Geotechnics 2, nr 1 (1.02.2022): 158–70. http://dx.doi.org/10.3390/geotechnics2010007.

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Strong interactions between mechanical deformation and chemical reactions may play a critical role in the response of geomaterials or geological systems to evolving environmental circumstances that may occur in both natural and engineered processes. The present study focuses on mineral dissolution and precipitation at the intergranular contact whose consequences are often manifested at the macro-scale where the mechanical and transport properties of the geomaterial may be altered. Discrete element modeling is employed to explore two applications involving such mineral transformations. The first example is primarily focused on the chemo-mechanical coupling mechanisms of intergranular contact in the natural process of pressure solution and secondary compression. The effect of the mineral dissolution on the mechanical response at the grain contact is incorporated into the contact model. Discrete element simulations are performed to examine the overall mechanical response of particle assembles subject to mineral dissolution and the results demonstrate the important role of the kinetic rate characteristics of the dissolution process. The second part of the present study revolves around the effect of mineral precipitation in an engineered process known as microbially induced calcite precipitation for potential soil improvement. The kinetics of involved bio-chemical process is incorporated into on the contact model and the simulation results indicate considerable strengthening effect. Overall, the present study demonstrates the feasibility of discrete element approach as a numerical tool to model coupled chemo-mechanical phenomena across the scales.

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Rammelkamp, Kristin, Susanne Schröder, Alessandro Pisello, Gianluigi Ortenzi, Frank Sohl i Vikram Unnithan. "Explorative Data Analysis Methods: Application to Laser-Induced Breakdown Spectroscopy Field Data Measured on the Island of Vulcano, Italy". Sensors 23, nr 13 (7.07.2023): 6208. http://dx.doi.org/10.3390/s23136208.

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One of the strengths of laser-induced breakdown spectroscopy (LIBS) is that a large amount of data can be measured relatively easily in a short time, which makes LIBS interesting in many areas, from geomaterial analysis with portable handheld instruments to applications for the exploration of planetary surfaces. Statistical methods, therefore, play an important role in analyzing the data to detect not only individual compositions but also trends and correlations. In this study, we apply two approaches to explore the LIBS data of geomaterials measured with a handheld device at different locations on the Aeolian island of Vulcano, Italy. First, we use the established method, principal component analysis (PCA), and second we adopt the principle of the interesting features finder (IFF), which was recently proposed for the analysis of LIBS imaging data. With this method it is possible to identify spectra that contain emission lines of minor and trace elements that often remain undetected with variance-based methods, such as PCA. We could not detect any spectra with IFF that were not detected with PCA when applying both methods to our LIBS field data. The reason for this may be the nature of our field data, which are subject to more experimental changes than data measured in laboratory settings, such as LIBS imaging data, for which the IFF was introduced first. In conclusion, however, we found that the two approaches complement each other well, making the exploration of the data more intuitive, straightforward, and efficient.

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Nova, R., R. Castellanza i C. Tamagnini. "A constitutive model for bonded geomaterials subject to mechanical and/or chemical degradation". International Journal for Numerical and Analytical Methods in Geomechanics 27, nr 9 (2003): 705–32. http://dx.doi.org/10.1002/nag.294.

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Pathak, Shashank, i G. V. Ramana. "On Stress–Strain Function of Geomaterials Subjected to Blast-Loads". Indian Geotechnical Journal 51, nr 3 (18.04.2021): 520–38. http://dx.doi.org/10.1007/s40098-021-00527-6.

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Wang, Lu Jun, i Zhi Yong Ai. "Transient Thermal Response of a Multilayered Geomaterial Subjected to a Heat Source". KSCE Journal of Civil Engineering 22, nr 9 (2.04.2018): 3292–301. http://dx.doi.org/10.1007/s12205-018-2035-x.

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Mehra, Sagar, i Ashutosh Trivedi. "Pile Groups Subjected to Axial and Torsional Loads in Flow-Controlled Geomaterial". International Journal of Geomechanics 21, nr 3 (marzec 2021): 04021002. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0001928.

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Zhu, Wan Cheng, K. T. Chau i Chun An Tang. "Numerical Simulation on Failure Patterns of Rock Discs and Rings Subject to Diametral Line Loads". Key Engineering Materials 261-263 (kwiecień 2004): 1517–22. http://dx.doi.org/10.4028/www.scientific.net/kem.261-263.1517.

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Brazilian test is a standardized test for measuring indirect tensile strength of rock and concrete disc (or cylinder). Similar test called indirect tensile test has also been used for other geomaterials. Although splitting of the disc into two halves is the expected failure mode, other rupture modes had also been observed. More importantly, the splitting tensile strength of rock can vary significantly with the specimen geometry and loading condition. In this study, a numerical code called RFPA2D (abbreviated from Rock Failure Process Analysis) is used to simulate the failure process of disc and ring specimens subject to Brazilian test. The failure patterns and splitting tensile strengths of specimens with different size and loading-strip-width are simulated and compared with existing experimental results. In addition, two distinct failure patterns observed in ring tests have been simulated using RFPA2D and thus this verifies the applicability of RFPA2D in simulating rock failure process under static loads.

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Murray, Ian, i Alessandro Tarantino. "Mechanisms of failure in saturated and unsaturated clayey geomaterials subjected to (total) tensile stress". Géotechnique 69, nr 8 (sierpień 2019): 701–12. http://dx.doi.org/10.1680/jgeot.17.p.252.

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Zhou, Xiao-Ping, i Chang-Qing Li. "Permeability prediction of porous geomaterials subjected to freeze-thaw cycles based on 3D reconstruction technology". Cold Regions Science and Technology 181 (styczeń 2021): 103180. http://dx.doi.org/10.1016/j.coldregions.2020.103180.

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Çoşkun, Canberk, i Tamer Rızaoğlu. "Investigation of the Physical, Mechanical and Aesthetic Characteristics of Terrazo Tiles Obtained from Different Rock Aggregates". Multidisciplinary Aspects of Production Engineering 3, nr 1 (1.09.2020): 477–90. http://dx.doi.org/10.2478/mape-2020-0040.

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AbstractThroughout history, people have covered the floors of the buildings with materials such as carpet, rock pieces, wood, mosaic, ceramic and tile according to the conditions of the day due to their desire to protect them from moisture, make them hygienic environment easy to clean and give an aesthetic appearance. The merging of mechanization with cement based materials with the industrial revolution in the 19th century has brought along the development of diversity and different production methods in these floor covering materials. One of these coating materials is terrazo tiles that form the subject of the current paper. Terrazo tiles are materials obtained by pressing the mortar obtained by mixing water, cement, marble powder and aggregate in certain proportions. Within the scope of this research, it was aimed to provide alternative raw materials to the tile body and to transform the rock pieces, which are found in waste form in natural stone workshops, into the economy. For this purpose, geomaterials collected from magmatic, metamorphic and sedimentary rocks cropped in the Kahramanmaraş-Antakya-Elazığ regions and natural stone workshops operating in Kahramanmaraş city, were classified according to their geological origins and aggregates of 4.75-12 mm were obtained with the help of jaw crushers and sieves. Tiles have been produced in accordance with the method of tile production from sized aggregates. The produced tiles were kept in the water pool for 28 days and surface controls were made. According to the physical and mechanical test results applied to the tile samples, water absorption by weight is 5.31-13.25%, bending strength 4.95-8.89 MPa, Böhme abrasion resistance 1.09-3.43 cm3/50cm2, mass loss after freeze-thaw is observed to be in the range of 0.97-1.59%. On the other hand, the surface roughness of the tiles prepared with coarse rock aggregates was found to be relatively lower than the tile samples obtained with fine grained rock aggregates. The obtained results indicate that the geomaterials subject to the research can be used as an alternative raw material source in tile production and these raw materials will provide new benefits to the construction field.

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Bulíček, Miroslav, Tomáš Los, Yong Lu i Josef Málek. "On planar flows of viscoelastic fluids of Giesekus type". Nonlinearity 35, nr 12 (25.11.2022): 6557–604. http://dx.doi.org/10.1088/1361-6544/ac9a2c.

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Abstract Viscoelastic rate-type fluid models of higher order are used to describe the behaviour of materials with complex microstructure: geomaterials like asphalt, biomaterials such as vitreous in the eye, synthetic rubbers such as styrene butadiene rubber. A standard model that belongs to the category of viscoelastic rate-type fluid models of the second order is the model due to Burgers, which can be viewed as a mixture of two Oldroyd-B models of the first order. This viewpoint allows one to develop the whole hierarchy of generalized models of the Burgers type. We study one such generalization that can be viewed as a combination (mixture) of two Giesekus viscoelastic models having in general two different relaxation mechanisms. We prove, in two spatial dimensions, long-time and large-data existence of weak solutions to the considered generalization of the Burgers model subject to no-slip boundary condition. We also provide, as a particular case, a complete proof of global-in-time existence of weak solutions to the Giesekus model in two spatial dimensions.

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Daag, Arturo S., Oliver Paul C. Halasan, Arielle Anne T. Magnaye, Rhommel N. Grutas i Renato U. Solidum. "Empirical Correlation between Standard Penetration Resistance (SPT-N) and Shear Wave Velocity (Vs) for Soils in Metro Manila, Philippines". Applied Sciences 12, nr 16 (12.08.2022): 8067. http://dx.doi.org/10.3390/app12168067.

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The measurement of the shear wave velocities (Vs) of soils is an important aspect of geotechnical and earthquake engineering, due to its direct relation to the shear modulus (G), which in turn influences the stress–strain behavior of geomaterials. Vs can be directly measured or estimated using a variety of onsite tests or in a laboratory. Methods such as downhole PS logging require boreholes and may not be logistically and economically feasible in all situations. Many researchers have estimated Vs from other geotechnical parameters, such as standard penetration test resistance (SPT-N), by means of empirical correlations. This paper aimed to contribute to this subject by developing an empirical relationship between Vs and SPT-N. Data from twenty sites in Metro Manila were obtained from geotechnical investigation reports. Vs profiles of the same sites were also acquired using the refraction microtremor method. New empirical relationships were developed for all, sandy, and clayey soil types, using a non-linear regression method that is applicable for Metro Manila soils. Statistical evaluation and comparison of the proposed correlations with other previous works suggested the viability of the empirical model.

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Pękala, Agnieszka, Michał Musiał i Tomasz Galek. "Pyritization in Stone-Building Materials Modeling of Geochemical Interaction". Sustainability 14, nr 20 (14.10.2022): 13206. http://dx.doi.org/10.3390/su142013206.

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Stone-building materials, despite their natural origin, must be tested for the concentration of trace elements necessary to assess their impact on the environment and humans. In addition to basic research determining their mineral composition and structural and textural features, it is important to analyze the geochemical interactions between the material matrix and the concentration of elements that have a negative impact on the surrounding natural environment and our health. In the presented study, mineralogical and geochemical studies were carried out on the Carpathian sandstones. It was shown that the studied sandstones are represented by lithic wackes and sublithic arenites. Rocks subject to the secondary process of sulfide mineralization were observed among sublithic arenites. Pyrite in the studied geomaterials took various forms. A detailed geochemical analysis was carried out in the material in which iron sulfides acted as a binder. The research was aimed at identifying possible variations in the concentration of elements, with a particular emphasis on the contact between the silica and mineralized phases. The assessment of the geochemical interaction of iron sulfides with silica at a successively enlarged measurement was carried out using the Mamdani–Assilian fuzzy inference model.

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Nguyen, Trung-Kien, Thanh-Trung Vo i Nhu-Hoang Nguyen. "DEM investigation on strain localization in a dense periodic granular assembly with high coordination number". Frattura ed Integrità Strutturale 16, nr 59 (22.12.2021): 188–97. http://dx.doi.org/10.3221/igf-esis.59.14.

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Strain localization is one of key phenomena which have been studied extensively in geomaterials and for different kinds of materials including metals and polymers. This well-known phenomenon appears when structure/material is closed to failure. Theoretical, experimental, and numerical research have been dedicated to this subject for a long while. In the numerical aspects, strain localization inside the periodic granular assembly has not been well studied in the literature. In this paper, we investigate the occurrence and development of strain localization within a dense cohesive-frictional granular assembly with high coordination number under bi-periodic boundary conditions by Discrete Element Modeling (DEM). The granular assembly is composed of 2D circular disks and subjected to biaxial loading with constant lateral pressure. The results show that the formation of shear bands is of periodic type, consistent with the boundary conditions. This formation has the origins of the irreversible losing of cohesive contacts, viewed as micro-crackings which strongly concentrated in the periodic shear zones. This micromechanical feature is therefore strongly related to the strain localization observed at the sample scale. Finally, we also show that the strain localization is in perfect agreement with the sample’s displacement fluctuation fields.

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Wang, X. B. "Residual Stress Distribution in Pure Bending Beam Subjected to Tensile Failure on One Side". Materials Science Forum 524-525 (wrzesień 2006): 253–58. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.253.

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The stress distribution on the midsection of a pure bending beam where tensile strain localization band initiates on the tensile side of the beam and propagates within the beam is analyzed. Using the static equilibrium condition on the section of the midspan of the beam and the assumption of plane section as well as the linear softening constitutive relation beyond the tensile strength, the expressions for the length of tensile strain localization band and the distance from the tip of the band to the neutral axis are derived. After superimposing a linear unloading stress distribution over the initial stress distribution, the residual stress distribution on the midsection of the beam is investigated. In the process of strain localization band’s propagation, strain-softening behavior of the band occurs and neutral axis will shift. When the unloading moment is lower, the length of tensile strain localization band remains a constant since the stress on the base side of the beam is tensile stress. While, for larger unloading moment, with an increase of unloading moment, the length of tensile strain localization band decreases and the distance from the initial neutral axis to the unloading neutral axis increases. The neutral axis of midsection of the beam will shift in the unloading process. The present analysis is applicable to some metal materials and many quasi-brittle geomaterials (rocks and concrete, etc) in which tensile strength is lower than compressive strength. The present investigation is limited to the case of no real crack. Moreover, the present investigation is limited to the case that the length of strain localization band before unloading is less than half of depth of the beam. Otherwise, the residual tensile stress above the elastic neutral axis will be greater than the tensile strength, leading to the further development of tensile strain localization band in the unloading process.

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Martín, M. Martín, Sanz de Galdeano i S. Moliner Aznar. "The Geological Heritage of Salobreña (South Spain): example of a touristic area". American Research Journal of Earth Science 2, nr 1 (25.02.2021): 1–17. http://dx.doi.org/10.21694/2642-3022.21001.

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Salobreña consist of a touristic area with a typical Andalusian white town built on a hill and crowned with a Castle from the medieval era of Moors occupation. The urban area is bordered by fields of tropical crops and fruit trees that, together with its location by the sea, confer on Salobreña a beautiful postcard. These features, as a whole, are an attraction for visitors. Although the authorities are very interested in developing the beach tourism and displaying and protecting the historical center of the town, the interest in geological heritage is negligible. So, this paper tries to expose and evaluate the sites of geologic interest recognizable in the area, so that not only tourists and visitors, but also students, are offered more attractions for their visits. 30 sites are proposed as suitable to be considered as geological heritage, organized in three accessible walking itineraries named respectively: Urban, Panoramic and Littoral georoutes. The selected sites display a great variety of geological typologies as structural geology, stratigraphy, sedimentology, geomaterials, petrology, mineralogy, geomorphology and hydrogeology-hydraulics. Avoiding subjectivity, the sites and georoutes have been classified and ranked with a numerical methodology based on recent literature. The Scientific Value (SV), Potential Educational Value (PEV), Potential Touristic Value (PTV) have been quantified by using several criteria in each case. This allows visitors and teachers to select the most suitable route according to their goals. The Degradation Risk (DR) has also been evaluated, giving key geo-conservation actions. This plan can be presented to political and technical managers from Salobreña Town. Finally, some actions are proposed for better conservation of the sites but also to contribute to education and promote cultural tourism. These actions would also favor educational activities for students of all levels in earth science subjects, but also increase economic activity and sustainable development in the area by incorporating cultural visitors.

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Alvarez-Borges, Fernando, Genoveva Burca, Robert Atwood, Andrew James, Mark Wolstenholme i Sharif Ahmed. "Correlative neutron and X-ray tomography imaging of pile installation in chalk". Géotechnique, 25.07.2022, 1–32. http://dx.doi.org/10.1680/jgeot.21.00318.

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Neutron and X-ray tomography (NCT and XCT, respectively) are imaging techniques increasingly being applied in geomechanics research. They are used to non-destructively reveal different microstructural aspects of geomaterials: XCT is often used to observe/quantify differences in density or porosity, while NCT reveals the presence and distribution of hydrogenous materials such as water. The correlated use of NCT and XCT for geomechanics and geotechnics research is in its infancy. To this date, very few experiments have been carried out that combine both techniques, and none have been used to investigate geomaterial-structure interaction. This paper presents the first correlative NCT-XCT imaging study of pile installation. A scaled model pile was installed in an unsaturated intact chalk cylinder and in-situ NCT and ex-situ XCT synchrotron-based imaging was applied consecutively. Chalk was used because the behaviour of displacement piles installed in this material is still subject to considerable uncertainty. Results reveal for the first time the interaction between installation-induced changes in chalk density and water distribution variations, with evidence of water displacement into the densified material in the vicinity of the installed pile. A straightforward method for correlative bulk density-moisture content determination from NCT-XCT images of geomaterials are presented and their limitations discussed.

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Farrag, Rabie. "Shear Demands of Rock-Socketed Piles Subject to Cyclic Lateral Loading". DFI Journal The Journal of the Deep Foundations Institute 14, nr 2 (31.12.2020). http://dx.doi.org/10.37308/dfijnl.20200526.223.

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The determination of internal pile reactions is critical to designing and assessing the structural performance of deep foundations. Internal shear and moment profiles strongly depend on lateral pile-soil interaction, which in turn depends on pile and soil stiffnesses as well as the stiffness contrast between soft and stiff strata, such as occurs at a soil/rock interface. At zones of strong geomaterial stiffness contrast, Winkler-spring-type analyses predict abrupt changes in the internal pile reactions for laterally-loaded foundation elements. In particular, the sudden deamplification of internal moments when transitioning from a soft to stiff layer is accompanied by amplification of pile shear. This “shear spike” can result in bulky transverse reinforcement designs for drilled shaft rock sockets that pose constructability challenges due to reinforcement congestion, increasing the risk of defective concrete on the outside of the cage. This paper presents an experimental research program of three large-scale, instrumented drilled shafts with simulated rock sockets constructed from concrete. Each shaft had a different transverse reinforcement design intended to bound the amplitude of the predicted amplified shear demand, with a particular emphasis on performance of shafts with shear resistance less than the predicted demand and below the code minimum. Test results suggested that the shafts experienced a flexure-dominated failure irrespective of the transverse reinforcement detailing.

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