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1
Arpit Kumbhar and Dr. Ajay Radke. "Vertical Extension and Retrofitting of the Existing R.C.C. Commercial Building – A review." International Research Journal on Advanced Engineering Hub (IRJAEH) 2, no. 03 (March 20, 2024): 559–63. http://dx.doi.org/10.47392/irjaeh.2024.0081.
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This study explores the feasibility of vertically extension of existing buildings as a sustainable solution to urban densification, particularly focusing on the structural implications and potential benefits of such extensions. Through structural analysis using advanced software like ETAB, and SAFE. as well as examination of cost-effectiveness, the research evaluates the viability of vertical extensions in different contexts. Case studies from various regions, illustrate the technical challenges and benefits associated with vertical extension projects. The analysis encompasses considerations such as structural stability of existing building after floor extensions, and cost implications, offering insights into the most efficient methods for extending buildings vertically. This research underscores the importance of vertical extension as a sustainable urban development strategy and calls for greater awareness and adoption of this approach within the construction industry. It emphasizes the need for collaborative efforts among stakeholders and proposes a development process to streamline the implementation of vertical extension projects.
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Douša, Jan, and Pavel Václavovic. "Results of GPS reprocessing campaign (1996-2011) provided by Geodetic observatory Pecný." Geoinformatics FCE CTU 9 (December 22, 2012): 77–90. http://dx.doi.org/10.14311/gi.9.7.
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The paper presents the GOP first reprocessing results, which officially contributed to the EPN-repro1 project. It also describes the 15-year GOP cumulative solution providing station coordinates, velocities and their discontinuities over the period of 1996-2011. Repeatabilities estimated from cleaned long-term coordinate time-series reached 1-2 mm and 4-6 mm in horizontal and vertical component, respectively. We then showed the exploitation of GOP reprocessing results in the assessment of the EUREF ITRF2005 densification and the latest ITRS realization, ITRF2008. We identified and confirmed the North-South tilt (≈ 2mas) in the currently available European reference frame based on the EPN cumulative solution updated in GPS week 1600. The study showed a historical development of the tilt and its close relation to a weak velocity datum definition of this realization, which is very important for a long-term datum prediction. Selected EPN station coordinates, velocities and discontinuities of the latest ITRS realization (ITRF2008) were also assessed. Specific problems for some EPN stations were identified in the global reference frame. This emphasized further necessity to check all the stations before their use for datum definition for regional densifications.
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Zheng, Siqi. "Feasibility study on infilling of horizontal wells with difficult to recover reserves in Fuyu reservoir." E3S Web of Conferences 329 (2021): 01042. http://dx.doi.org/10.1051/e3sconf/202132901042.
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Aiming at the inter well drive immobile remaining oil in Fuyu oil layer of block 1 due to the non densification of surface village coverage, taking into account the undeveloped reserves that can not be produced by vertical wells due to being located in the wetland protection area along the river, the feasibility study of layered densification of horizontal wells in the main oil layer with good reservoir development is carried out to explore a new densification mode of horizontal wells in Fuyu tight oil reservoir.
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Zhong, Ji Xiang. "Subgrade Compaction Boundary Layer Detection Method and Detection System." Advanced Materials Research 639-640 (January 2013): 1259–64. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.1259.
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At present, the degree of compaction is the main criterion for subgrade compaction quality.It is the relative expression of the compacted density,Just average.It does not adequately reflect the subgrade compaction layer vertical compaction density distribution law. Compaction boundary layer micro-unit compression pressure on in the process of pressure transmission decreases gradually until they reach the critical formation pressure dense layer. Compaction by detecting the boundary layer vertical zone layer densification, to calculate the boundary thickness, to draw isodense of densification. a clear reproduction of the compacted layer vertical compaction density distribution law. This paper describes the detection principles and detection methods of the compaction boundary layer. describes in detail functional structure and system design of the vehicle automatic detection system used to detect compaction boundary layer of each vertical zone.
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Denies, N., J. Canou, J. N. Roux, and A. Holeyman. "Vibrocompaction properties of dry sand." Canadian Geotechnical Journal 51, no. 4 (April 2014): 409–19. http://dx.doi.org/10.1139/cgj-2012-0436.
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The fundamental understanding of the behaviour of dry sand as it is being vibrated is necessary to properly address a number of engineering issues, such as the vibrocompaction process. The present paper first summarizes experimental works focusing on the effects of vibrations on the volume change of dry cohesionless soils. Original experiments characterizing the behaviour of dry sand subjected to vertical vibration are then presented. The volume change and the motion pattern displayed by vertically vibrated sand particles are discussed. When cohesionless soil, placed in a cylindrical container, is vertically vibrated under the gravitational field (g), experiments performed on dry Fontainebleau sand allow the distinction between three types of dynamic behaviours depending on the acceleration amplitude (a): the densification behaviour (a/g < 1), the instability surface behaviour (a/g ≈ 1), and the vibrofluid behaviour (a/g > 1). In the densification range, the sand simply settles. When the acceleration amplitude is increased beyond 1g, granular convection is observed and there is an instability in the sand mass leading to the emergence of an inclined free surface. If the acceleration amplitude is further increased, the free surface progressively flattens. There is an impressive dilatation of the whole sample and grain saltation is observed. The sand becomes fully vibrofluidized. The efficiency of the vibrocompaction process is finally discussed especially with regard to these dynamic behaviours.
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An, Xizhong, Fei Huang, Kejun Dong, and Xiaohong Yang. "DEM simulation of binary sphere packing densification under vertical vibration." Particulate Science and Technology 36, no. 6 (March 31, 2017): 672–80. http://dx.doi.org/10.1080/02726351.2017.1292335.
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Mirza Gheitaghy, Amir, René H. Poelma, Leandro Sacco, Sten Vollebregt, and Guo Qi Zhang. "Vertically-Aligned Multi-Walled Carbon Nano Tube Pillars with Various Diameters under Compression: Pristine and NbTiN Coated." Nanomaterials 10, no. 6 (June 18, 2020): 1189. http://dx.doi.org/10.3390/nano10061189.
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In this paper, the compressive stress of pristine and coated vertically-aligned (VA) multi-walled (MW) carbon nanotube (CNT) pillars were investigated using flat-punch nano-indentation. VA-MWCNT pillars of various diameters (30–150 µm) grown by low-pressure chemical vapor deposition on silicon wafer. A conformal brittle coating of niobium-titanium-nitride with high superconductivity temperature was deposited on the VA-MWCNT pillars using atomic layer deposition. The coating together with the pillars could form a superconductive vertical interconnect. The indentation tests showed foam-like behavior of pristine CNTs and ceramic-like fracture of conformal coated CNTs. The compressive strength and the elastic modulus for pristine CNTs could be divided into three regimes of linear elastic, oscillatory plateau, and exponential densification. The elastic modulus of pristine CNTs increased for a smaller pillar diameter. The response of the coated VA-MWCNTs depended on the diffusion depth of the coating in the pillar and their elastic modulus increased with pillar diameter due to the higher sidewall area. Tuning the material properties by conformal coating on various diameter pillars enhanced the mechanical performance and the vertical interconnect access (via) reliability. The results could be useful for quantum computing applications that require high-density superconducting vertical interconnects and reliable operation at reduced temperatures.
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Solovev, S. A., O. V. Soloveva, I. G. Akhmetova, Y. V. Vankov, and R. Z. Shakurova. "Numerical investigation of the thermal conductivity of a composite heat-insulating material with microgranules." Power engineering: research, equipment, technology 24, no. 1 (May 24, 2022): 86–98. http://dx.doi.org/10.30724/1998-9903-2022-24-1-86-98.
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THE PURPOSE. To consider the problems that arise when creating a composite heatinsulating material, including a layer of microspherical granules. Numerical modeling of a composite material with different volume content of microspheres and different options for the formation of voids. Determination of the influence of the presence of zones not occupied by microgranules on the insulating properties of the composite material. Determination of the influence of the volume content of microspherical granules on the heat flux through the composite material.METHODS. Numerical simulation was carried out by creating models of elementary cubic cells of a composite with a package of 27 microspheres in the ANSYS Fluent 19.2 software package. The evaluation of the insulating properties was carried out by measuring the thermal conductivity coefficient.RESULTS. The article investigates the influence of the presence of zones not occupied by microspherical granules on the thermal insulation properties of a composite material. Models of elementary cubic cells with different volume content of microgranules are constructed. Models of elementary cells are built with various options for the formation of voids, such as the removal of a vertical or horizontal row of granules and the compaction of granules vertically or horizontally.CONCLUSION. The removal of microgranules has a significant effect on the insulating properties of the composite. The lowest thermal conductivity coefficient was obtained for a simple cubic cell with a volume content of microgranules φ = 40%. The presence of voids in the material contributes to large heat losses, and in the case of a vertical through channel, the heat losses are greater than for a horizontal through channel. In the case of densification of spheres, heat losses in the zone not occupied by microgranules are compensated by a decrease in the heat flux in the area with densification of spheres.
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Endo, Yasoichi, Yuji Kominami, and Shouji Niwano. "Dependence of new-snow density on slope angle." Annals of Glaciology 26 (1998): 14–18. http://dx.doi.org/10.3189/1998aog26-1-14-18.
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The mass per unit horizontal area, vertical height and density of new snow accumulated on various slopes of 0° to 75° were measured. Although the mass of new snow on these slopes was nearly the same, vertical height increased and density decreased with increase of slope angle. Differences in heights and densities of new snow due to slope angle were explained by considering both accumulation and densification processes on the slopes.
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Endo, Yasoichi, Yuji Kominami, and Shouji Niwano. "Dependence of new-snow density on slope angle." Annals of Glaciology 26 (1998): 14–18. http://dx.doi.org/10.1017/s0260305500014464.
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The mass per unit horizontal area, vertical height and density of new snow accumulated on various slopes of 0° to 75° were measured. Although the mass of new snow on these slopes was nearly the same, vertical height increased and density decreased with increase of slope angle. Differences in heights and densities of new snow due to slope angle were explained by considering both accumulation and densification processes on the slopes.
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Sundling, Rikard, Åke Blomsterberg, and Anne Landin. "Enabling energy-efficient renovation: the case of vertical extension to buildings." Construction Innovation 19, no. 1 (March 5, 2019): 2–14. http://dx.doi.org/10.1108/ci-04-2018-0034.
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Purpose This paper is based on a study of six similar buildings built in Gothenburg, Sweden, in 1971, which were in urgent need of renovation. A life cycle profit analysis shows how four competing concepts were evaluated to find a financially viable renovation concept; additionally, the environmental impacts of these renovation concepts using a life cycle assessment are presented. Design/methodology/approach Four renovation concepts are compared to find the most appropriate concept, namely, minimalist, code-compliant, low-energy and low-energy plus vertical extension concepts. The methods used for comparison are life cycle profit analysis and life cycle impact assessment; the methods used for data gathering included site visits, interviews, document study, co-benefits study and energy simulation. Findings The findings show that vertical extension supported the energy-efficient renovation of the buildings and that the combination of low-energy and the vertical extension had the highest return on investment and the lowest environmental impact. The selected concept for renovating the remaining five buildings combined was the low-energy plus vertical extension. Additional benefits from vertical extension include more apartments in central locations for the housing company, a wider variety of apartment layouts and a wider range of tenants. Drawbacks include increased use of infrastructure, green space and common appliances, as well as gentrification. Originality/value This study shows how a vertical extension can financially enable an energy-efficient renovation and further lower its environmental impact. Benefits and drawbacks of densification are also highlighted to better understand the implementation of vertically extending a building.
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FUJITA, SHUJI, KUMIKO GOTO-AZUMA, MOTOHIRO HIRABAYASHI, AKIRA HORI, YOSHINORI IIZUKA, YUKO MOTIZUKI, HIDEAKI MOTOYAMA, and KAZUYA TAKAHASHI. "Densification of layered firn in the ice sheet at Dome Fuji, Antarctica." Journal of Glaciology 62, no. 231 (February 2016): 103–23. http://dx.doi.org/10.1017/jog.2016.16.
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ABSTRACTIn order to better understand the densification of polar firn, firn cores from the three sites within ~10 km of Dome Fuji, Antarctica, were investigated using surrogates of density: dielectric permittivities εv and εh at microwave frequencies with electrical fields in the vertical and horizontal planes respectively. Dielectric anisotropy Δε (=εv − εh) was then examined as a surrogate of the anisotropic geometry of firn. We find that layered densification is explained as a result of complex effects of two phenomena that commonly occur at the three sites. Basically, layers with initially smaller density and smaller geometrical anisotropy deform preferentially throughout the densification process due to textural effects. Second, layers having a higher concentration of Cl− ions deform preferentially during a limited period from the near surface depths until smoothing out of layered Cl− ions by diffusion. We hypothesize that Cl− ions dissociated from sea salts soften firn due to modulation of dislocation movement. Moreover, firn differs markedly across the three sites in terms of strength of geometrical anisotropy, mean rate of densification and density fluctuation. We hypothesize that these differences are caused by textural effects resulting from differences in depositional conditions within various spatial scales.
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Abdelsalam AEH, Ahmed Ehab. "Sustainable Vertical Urbanism as a Design Approach to Change the Future of Hyper Density Cities." Journal of Advance Research in Mechanical & Civil Engineering (ISSN: 2208-2379) 5, no. 7 (July 31, 2018): 01–12. http://dx.doi.org/10.53555/nnmce.v5i7.300.
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This paper focuses on introducing Sustainable Vertical Urbanism (SVU) as an approach for designing hybrid buildings and upgrading the public realm, making full use of the vertical dimension in hyper density cities. Mixed use tall buildings offer greater potential for contributing to the city economy, vitality and public interaction, compared to closed single-use glassy towers. Mixed use buildings bring new challenges in planning, morphology and technology. Unusual functions can be included in tall buildings such as vertical education , vertical public realm, vertical health care and vertical farming, plus integration with public transport. SVU is a new approach for densification of the city, coping with the pressures of urbanization, transport connectivity, environmental urban health; SVU can change people attitudes to living, working and enjoying culture in the city.
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S. O, Oladosu, and Ehigiator-Irughe R. "ASSESSMENT OF 3D POSITIONAL ACCURACY OF GEODETIC OBSERVATIONS FROM SINGLE CORS." Geological Behavior 6, no. 2 (2022): 101–6. http://dx.doi.org/10.26480/gbr.02.2022.101.106.
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Geodetic observations for both vertical and horizontal control networks cannot be compromised for any reason in accuracy and precision in the field of geomatics. Due to the error-prone nature of survey measurements, standards are established to allow for comparing the obtained results with a set of guidelines, regulations, or pre-determined specifications. The University of Benin’s Ugbowo Campus in Nigeria does not have enough control points, which informs this study. The densification of more reliable control points using the most recent technology is necessary. Before the observations, control network design, excavation, casting, and monumentation of first-order compliance beacons had been completed. Eight GNSS receivers were connected to the CORS_Geosystems multi-link access point and simultaneously deployed for observations. The stages involve the adjustment of observed data, the presentation of adjusted results, and the determination of horizontal and vertical accuracies. The result of horizontal accuracy showed that the RAPH_GNSS_08 station had the highest horizontal accuracy standard ratio of 1:432,193, while the Raph_GNSS_04 station had the lowest, 1:133,271. The highest vertical accuracy standard was 4.0mm, achieved between Cors_Geo and RAPH_GNSS_09, while the lowest, which was 3.1mm, was observed between Cors_Geo and RAPH_GNSS_08. High-precision engineering projects in the research area will benefit from the established first-order controls in terms of execution, monitoring, and maintenance. The Surveyors Council of Nigeria (SURCON) has recommended GNSS as one of the methods for achieving geodetic control densification in Nigeria.
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Koziatek, O., S. Dragićević, and S. Li. "GEOSPATIAL MODELLING APPROACH FOR 3D URBAN DENSIFICATION DEVELOPMENTS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B2 (June 7, 2016): 349–52. http://dx.doi.org/10.5194/isprs-archives-xli-b2-349-2016.
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With growing populations, economic pressures, and the need for sustainable practices, many urban regions are rapidly densifying developments in the vertical built dimension with mid- and high-rise buildings. The location of these buildings can be projected based on key factors that are attractive to urban planners, developers, and potential buyers. Current research in this area includes various modelling approaches, such as cellular automata and agent-based modelling, but the results are mostly linked to raster grids as the smallest spatial units that operate in two spatial dimensions. Therefore, the objective of this research is to develop a geospatial model that operates on irregular spatial tessellations to model mid- and high-rise buildings in three spatial dimensions (3D). The proposed model is based on the integration of GIS, fuzzy multi-criteria evaluation (MCE), and 3D GIS-based procedural modelling. Part of the City of Surrey, within the Metro Vancouver Region, Canada, has been used to present the simulations of the generated 3D building objects. The proposed 3D modelling approach was developed using ESRI’s CityEngine software and the Computer Generated Architecture (CGA) language.
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Koziatek, O., S. Dragićević, and S. Li. "GEOSPATIAL MODELLING APPROACH FOR 3D URBAN DENSIFICATION DEVELOPMENTS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B2 (June 7, 2016): 349–52. http://dx.doi.org/10.5194/isprsarchives-xli-b2-349-2016.
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With growing populations, economic pressures, and the need for sustainable practices, many urban regions are rapidly densifying developments in the vertical built dimension with mid- and high-rise buildings. The location of these buildings can be projected based on key factors that are attractive to urban planners, developers, and potential buyers. Current research in this area includes various modelling approaches, such as cellular automata and agent-based modelling, but the results are mostly linked to raster grids as the smallest spatial units that operate in two spatial dimensions. Therefore, the objective of this research is to develop a geospatial model that operates on irregular spatial tessellations to model mid- and high-rise buildings in three spatial dimensions (3D). The proposed model is based on the integration of GIS, fuzzy multi-criteria evaluation (MCE), and 3D GIS-based procedural modelling. Part of the City of Surrey, within the Metro Vancouver Region, Canada, has been used to present the simulations of the generated 3D building objects. The proposed 3D modelling approach was developed using ESRI’s CityEngine software and the Computer Generated Architecture (CGA) language.
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Palusci, Olga, and Carlo Cecere. "Urban Ventilation in the Compact City: A Critical Review and a Multidisciplinary Methodology for Improving Sustainability and Resilience in Urban Areas." Sustainability 14, no. 7 (March 26, 2022): 3948. http://dx.doi.org/10.3390/su14073948.
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In the last decades, a tendency towards urban tissue densification has been observed to counteract the urban sprawl. Densification may be achieved through more compact built areas, preferring the vertical to the horizontal development of buildings but avoiding bulky high-rise building blocks. This strategy significantly affects several aspects of the microclimate and produces direct and indirect effects on human health and well-being. In this regard, air pollution and heat stress constitute two increasing threats to human health and well-being that need to be faced immediately. The involved phenomena are various, intertwined, and may lead to conflicting results. Hence, regenerating existing, well-structured, and stratified urban areas by densification is not an easy challenge. Urban ventilation may favor the mitigation of detrimental effects of air pollution and heat stress on human life. Therefore, a multidisciplinary methodology is presented for embedding urban ventilation performance evaluation into urban management and planning processes. The scope is to propose a framework for urban renewal plans that is citizens-centered and aims at improving their health and well-being in existing urban areas. The methodology builds upon the performance-based approach and is supported by the conceptual framework and the literature reviews provided through the paper.
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Jaszak, Przemysław, Rafał Grzejda, Janusz Kluczyński, and Paweł Zmarzły. "Basic Design Parameters Influencing on Axial Stiffness of the Spiral Wound Gasket." Materials 16, no. 18 (September 14, 2023): 6209. http://dx.doi.org/10.3390/ma16186209.
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The article presents the influence of important design parameters of a spiral gasket on axial stiffness and leakage level. These parameters were the angle of inclination of the central part of the spiral section, the length of the vertical part of the spiral section, and the degree of densification of the material filling the metal coils. The scope of work was divided into two stages. In the first, experimental tests were conducted to determine the stiffness and tightness of a standard spiral gasket at two extreme levels of densification of the filler material, and the elastic–plastic properties of expanded graphite, which is the filler material of the metal spirals, were determined. In the second stage, multivariate numerical calculations were carried out to determine the axial stiffness of the gasket and to evaluate the distribution of contact pressure on the sealing surface. A novel aspect of the work is the proposal of a mathematical model to estimate the averaged value of the modulus of elasticity of the filler material as a function of the degree of densification and the execution of an experimental plan that significantly allowed the adoption of a limited number of analysed model variants used in the numerical calculations.
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Argenziano, M., D. Faiella, F. Bruni, C. De Angelis, M. Fraldi, and E. Mele. "Upwards - Vertical extensions of masonry built heritage for sustainable and antifragile urban densification." Journal of Building Engineering 44 (December 2021): 102885. http://dx.doi.org/10.1016/j.jobe.2021.102885.
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Salonen, Tarja, Jutta Hollands, Eldira Sesto, and Azra Korjenic. "Thermal Effects of Vertical Greening in Summer: An Investigation on Evapotranspiration and Shading of Façade Greening in Vienna." Buildings 12, no. 10 (October 17, 2022): 1705. http://dx.doi.org/10.3390/buildings12101705.
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Global urbanization is advancing, and with it, the densification of cities. Due to increased sealing of open spaces and the re-densification of existing urban settings, green spaces in the city are becoming scarcer. At the same time, greening within the urban fabric is known for its positive effects on the environment and decisively counteracts the urban heat effect. This study deals with the benefits of green façades for the environment as a cooling measure. Two façade greening systems, one trough and one cassette system, consisting of curtain wall elements with a basic metal structure, installed at a south-facing outdoor wall of a school building in Vienna, Austria, were taken under metrological examination. In order to evaluate the cooling effect caused by evapotranspiration, the amount of water evaporated was calculated using the difference of inflow and outflow. Furthermore, the surface temperatures of the greened and non-greened walls were measured to display the influence of the interaction of shading and evapotranspiration on the surrounding microclimate. The investigated vertical greening system with an area of 58 m2 has an average evaporation capacity of 101.38 L per day in the summer. The maximum surface temperature difference was measured to be 11.6 °C.
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Bell, Christina, Douglas Mair, David Burgess, Martin Sharp, Michael Demuth, Fiona Cawkwell, Robert Bingham, and Jemma Wadham. "Spatial and temporal variability in the snowpack of a High Arctic ice cap: implications for mass-change measurements." Annals of Glaciology 48 (2008): 159–70. http://dx.doi.org/10.3189/172756408784700725.
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AbstractInterpretation of ice mass elevation changes observed by satellite altimetry demands quantification of the proportion of elevation change which is attributable to variations in firn densification. Detailed stratigraphic logging of snowpack structure and density was carried out at ~1km intervals along a 47 km transect on Devon Ice Cap, Canada, in spring (pre-melt) and autumn (during/ after melt) 2004 and 2006 to characterize seasonal snowpack variability across the full range of snow facies. Simultaneous meteorological measurements were gathered. Spring (pre-melt) snowpacks show low variability over large spatial scales, with low-magnitude changes in density. The end-of-summer/ autumn density profiles show high variability in both 2004 and 2006, with vastly different melt regimes generating dissimilar patterns of ice-layer formation over the two melt seasons. Dye-tracing experiments from spring to autumn 2006 reveal that vertical and horizontal distribution of meltwater flow within and below the annual snowpack is strongly affected by the pre-existing, often subtle stratigraphic interfaces in the snowpack, rather than its bulk properties. Strong interannual variability suggests that using a simple relationship between air temperature, elevation and snowpack densification to derive mass change from measurements of elevation change across High Arctic ice caps may be misguided. Melt timing and duration are important extrinsic factors governing snowpack densification and ice-layer formation in summer, rather than averaged air temperatures.
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Wang, Ren, Kai Liu, Wanzhong Shi, Shuo Qin, Wei Zhang, Rong Qi, and Litao Xu. "Reservoir Densification, Pressure Evolution, and Natural Gas Accumulation in the Upper Paleozoic Tight Sandstones in the North Ordos Basin, China." Energies 15, no. 6 (March 9, 2022): 1990. http://dx.doi.org/10.3390/en15061990.
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The vague understanding of the coupling relationship among natural gas charging, reservoir densification, and pressure evolution restricted the tight gas exploration in the Lower Shihezi Formation of the Hangjinqi area, north Ordos Basin. In this study, the quantitative porosity evolution model, the pressure evolution process, and the natural gas charging history of tight sandstone reservoirs were constructed by integrated investigation of the reservoir property, the thin section, SEM and cathode luminescence observations, the fluid inclusion analysis and the 1D basin modeling. The results show that the compaction and cementation reduced the primary porosity by 21.79% and 12.41%, respectively. The densification of the reservoir occurred at circa 230 Ma, which was before the natural gas charging time from 192 to 132 Ma. The paleo-overpressure within the tight reservoirs occurred since the Middle Jurassic with the pressure coefficients between 1.1 and 1.55. The continuous uplifting since the Late Cretaceous resulted in the under- and normal-pressure of the Lower Shihezi Formation with the pressure coefficients ranging from 0.67 to 1.05. The results indicate that the densification of the reservoirs was conducive to the formation of paleo-pressure produced by gas generating. The gas predominantly migrated vertically, driven by gas expansion force rather than buoyance and displaced the pore water in the reservoirs near source rocks.
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Bukreev, V. I., and A. V. Gusev. "The effect of densification during mixing on the spreading of a vertical round jet." Doklady Earth Sciences 439, no. 1 (July 2011): 1002–5. http://dx.doi.org/10.1134/s1028334x11070130.
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Marcato, Marilia Bassetti, Esther Dweck, and Rafael Montanha. "The densification of Chinese production chains in the context of vertically fragmented production." Structural Change and Economic Dynamics 60 (March 2022): 75–89. http://dx.doi.org/10.1016/j.strueco.2021.11.004.
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Wang, Xiaoxia, Rongxian Zhu, Wencheng Lei, Qiupeng Su, and Wenji Yu. "The Optimization of Thermo-Mechanical Densification to Improve the Water Resistance of Outdoor Bamboo Scrimber." Forests 14, no. 4 (April 6, 2023): 749. http://dx.doi.org/10.3390/f14040749.
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The water resistance of bamboo scrimber used in outdoor environments greatly affects its applications and lifecycle. Physical and chemical studies have been conducted to investigate the influence of the hot-pressing temperature during thermo-mechanical densification on the water resistance of outdoor bamboo scrimber. Investigated parameters included the failure mode of surfaces, the vertical density profile, and the change of chemical components, which provides theoretical support for optimizing bamboo scrimber for outdoor applications. Here, the vertical density profiles of bamboo scrimber were measured using an X-ray density profiler, and the response of cells and bonding interfaces of bamboo scrimber to water absorption were recorded by using extended depth-of-field 3D microscopy and field emission scanning electron microscopy (FE-SEM). The composition was evaluated by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) to investigate the effect of temperature on water resistance during thermo-mechanical densification. The water resistance of bamboo scrimber significantly improved as the temperature increased from 140 °C to 170 °C. The spring-back from the compressive deformation of cells and cracks was the main failure mode, and showed a negative correlation upon increasing the temperature. The moderate increase in cellulose crystallinity, the increase in the polymerization degree of the PF resin, and the thermal degradation of hemicelluloses explained the failure behavior of the bamboo scrimber at the molecular level.
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Chu, Demiao, Jun Mu, Stavros Avramidis, Sohrab Rahimi, Shengquan Liu, and Zongyuan Lai. "Functionalized Surface Layer on Poplar Wood Fabricated by Fire Retardant and Thermal Densification. Part 1: Compression Recovery and Flammability." Forests 10, no. 11 (October 26, 2019): 955. http://dx.doi.org/10.3390/f10110955.
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To enhance compression stability and fire retardancy of densified wood, a new modification method i.e., combined nitrogen–phosphorus (NP) fire retardant pre-impregnation with surface thermo-mechanical densification is used to fabricate a certain thickness of functionalized surface layer on poplar. This combined treated wood is investigated via vertical density profile (VDP), and the compression stability is revealed by both soaking test and cone analysis. Results demonstrate that the combined treatment hardened the surface of wood and reformed the interface combination of the NP with the wood cell wall, thus making the surface tissue more close-grained. Fire retardancy was also enhanced; the total heat release and CO generation values decreased by 21.9% and 68.4%, respectively, when compared with that of solely NP-treated wood. Moreover, surface hardness increased by 15.8%, and the recovery of surface hardness and thickness were 56.8% and 77.2% lower than that of simply densified wood. It appears that this NP-involved thermal densification could be considered as an alternative approach to enhance both the compression stability and fire resistance of wood.
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Laukala, Teija, Johanna Lyytikäinen, Katriina Mielonen, and Kaj Backfolk. "Effect of PCC crystallization and morphology on flocculation with microfibrillated cellulose, on sheet densification and liquid absorption behavior." Cellulose 27, no. 17 (October 1, 2020): 10151–66. http://dx.doi.org/10.1007/s10570-020-03458-2.
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Abstract Composite sheets consisting of elongated and aggregated cationically charged precipitated calcium carbonate (PCC) and native microfibrillated cellulose (MFC) were prepared with a wet laying method. The furnishes were prepared with and without an anionic flocculating agent (polyacrylamide) in order to adjust the structure of the sheet. The samples were compressed (densified) in order to determine the particle and microfibrillated cellulose-PCC structure coalescence and densification, as well as its subsequent influence on liquid absorption behavior. The densification affected both the vertical and lateral distribution of PCC, but the flocculating agent enhanced the compression stability and stabilized the sheets against PCC material flow. The differences between the sheets made with and without the flocculation aid affected the absorption of an anionic dye-based fluid ink, which was evident as a higher print density and less print bleeding. The absorption behavior was dependent on the sheet structure, especially on the PCC distribution within the sheets. Finally, the role of MFC on floc structure and floc formation is discussed. Graphic abstract
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Inoue, Ryo, Shuji Fujita, Kenji Kawamura, Ikumi Oyabu, Fumio Nakazawa, Hideaki Motoyama, and Teruo Aoki. "Spatial distribution of vertical density and microstructure profiles in near-surface firn around Dome Fuji, Antarctica." Cryosphere 18, no. 1 (January 30, 2024): 425–49. http://dx.doi.org/10.5194/tc-18-425-2024.
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Abstract. To better understand the near-surface evolution of polar firn in low-accumulation areas (<30 mm w.e. yr−1), we investigated the physical properties – density, microstructural anisotropy of ice matrix and pore space, and specific surface area (SSA) – of six firn cores collected within 60 km of Dome Fuji, East Antarctica. The physical properties were measured at intervals of ≤0.02 m over the top 10 m of the cores. The main findings are (i) a lack of significant density increase in the top ∼4 m, (ii) lower mean density near the dome summit (∼330 kg m−3) than in the surrounding slope area (∼355 kg m−3) in the top 1 m, (iii) developments of a vertically elongated microstructure and its contrast between layers within the top ∼3 m, (iv) more pronounced vertical elongation at sites and periods with lower accumulation rates than those with higher accumulation rates, (v) a rapid decrease in SSA in the top ∼3 m, and (vi) lower SSA at lower-accumulation sites, but this latter trend is less pronounced than that of microstructural anisotropy. These observations can be explained by a combination of the initial physical properties on the surface set by wind conditions and the metamorphism driven by water vapor transport through the firn column under a strong vertical temperature gradient (temperature gradient metamorphism, TGM). The magnitude of TGM depends on the duration of firn layers under the temperature gradient, determined by the accumulation rate; longer exposure causes a more vertically elongated microstructure and lower SSA. Overall, we highlight the significant spatial variability in the near-surface physical properties over the scale of ∼100 km around Dome Fuji. These findings will help us better understand the densification over the whole firn column and the gas-trapping process in deep firn and possible difference in them between existing deep ice cores and the upcoming “Oldest-Ice” cores collected tens of kilometers apart.
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Hanna, Adel, and Ashraf Ghaly. "Ultimate pullout resistance of groups of vertical anchors." Canadian Geotechnical Journal 31, no. 5 (October 1, 1994): 673–82. http://dx.doi.org/10.1139/t94-079.
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A theoretical investigation on the group action of vertical screw anchors installed in sands is presented. An experimentally observed rupture surface for single anchors was employed to establish the shape of the rupture surface for groups of anchors. A theory was developed to predict the uplift capacity of groups of anchors with different configurations utilizing the theoretical model described in a companion paper. To calculate the uplift capacity, weight and shear factors for shallow and deep groups of anchors are established. These factors are presented as functions of the angle of shearing resistance of the sand, relative depth ratio of an individual anchor within the group, and (or) the ratio between the height of embedded failure bulb and anchor diameter. The effect of overconsolidation due to the compaction technique used in placing the sand was incorporated in the theoretical calculations of uplift capacity. Comparison between theoretical and experimental results shows good agreement in the case of loose and medium sands and satisfactory agreement in the case of dense sand. An empirical equation, based on theory and experimental data, is proposed to mathematically quantify the effect of densification-on the angle of shearing resistance of the sand. Key words : anchors, group action, limit equilibrium, overconsolidation ratio, theoretical analysis, uplift capacity.
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Vuckovic, Loibl, Tötzer, and Stollnberger. "Potential of Urban Densification to Mitigate the Effects of Heat Island in Vienna, Austria." Environments 6, no. 7 (July 10, 2019): 82. http://dx.doi.org/10.3390/environments6070082.
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Global increase of urban population has brought about a growing demand for more dwelling space, resulting in various negative impacts, such as accelerated urbanization, urban sprawl and higher carbon footprints. To cope with these growth dynamics, city authorities are urged to consider alternative planning strategies aiming at mitigating the negative implications of urbanization. In this context, the present contribution investigates the potential of urban densification to mitigate the heat island effects and to improve outdoor thermal conditions. Focusing on a quite densely urbanized district in Vienna, Austria, we carried out a set of simulations of urban microclimate for pre- and post-densification scenarios using the parametric modelling environment Rhinoceros 3D and a set of built-in algorithms in the Rhino’s plug-in Grasshopper. The study was conducted for a hot summer period. The results revealed a notable solar shielding effect of newly introduced vertical extensions of existing buildings, promoting temperature decrease and improved thermal conditions within more shaded urban canyons and courtyards. However, a slight warming effect was noted during the night-time due to the higher thermal storage and lower sky view factor.
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Criss, Robert, and Anne Hofmeister. "Galactic Density and Evolution Based on the Virial Theorem, Energy Minimization, and Conservation of Angular Momentum." Galaxies 6, no. 4 (November 15, 2018): 115. http://dx.doi.org/10.3390/galaxies6040115.
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Spiral galaxies are spinning, internally densified objects. The Virial Theorem explains galactic rotation curves via its linkage of the rotation rate to the gravitational self-potential (Ug) and the moment of inertia of oblate spheroids. We devise a new analytical solution that allows galactic mass and volumetric density (kg m−3) profiles to be extracted from velocity and its derivative as functions of equatorial radius. This inverse model of rotation curves is direct, unambiguous, and parameter-free. To probe galactic evolution, we combine energy minimization, angular momentum conservation, and the Virial Theorem. The characteristic flat shape of spiral galaxies results from an initial vertical collapse of a spinning, colossal molecular cloud, which reduces Ug while conserving angular momentum. Subsequent inward densification further lowers Ug, producing bulges, but conserving angular momentum requires mass loss, achieved by the outward movement of the distal parts of the spiral arms. Many of the evolutionary patterns of spiral galaxies are exhibited by the changing shapes of hurricanes during formation and dissipation. In contrast, elliptical galaxies evolve from a cloud with roughly random orbits into progressively rounder, internally denser objects, with angular momentum conserved by the development of vertically oriented jets. Galactic evolution is governed by the initial inventory of mass and angular momentum, resulting in separate paths for elliptical and spiral galaxies, as is codified in Hubble’s tuning fork diagram.
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Fujita, Shuji, Motohiro Hirabayashi, Kumiko Goto-Azuma, Remi Dallmayr, Kazuhide Satow, Jiancheng Zheng, and Dorthe Dahl-Jensen. "Densification of layered firn of the ice sheet at NEEM, Greenland." Journal of Glaciology 60, no. 223 (2014): 905–21. http://dx.doi.org/10.3189/2014jog14j006.
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AbstractDensification of firn at the North Greenland Eemian Ice Drilling (NEEM) camp is investigated using density surrogates: dielectric permittivities ∊v and ∊h at microwave frequencies with electrical fields in the vertical and horizontal planes, respectively. Dielectric anisotropy Δ∊ (= ∊v − ∊h) is then examined as a surrogate for the anisotropic geometry of firn. Its size, fluctuations and mutual correlations are investigated in samples taken at depths from the surface to ~90 m. The initial Δ∊ of ~0.06 appears within the uppermost 0.2 m. After that, Δ∊ decreases rapidly until 21–26 m depth. Below this, Δɛ decreases slowly. Layers with more ions of fluorine, chlorine and some cations deposited between the autumn and the subsequent summer deform preferentially during all these stages. This layered deformation is explained partly by the textural effects initially formed by the seasonal variation of metamorphism, and partly by ions such as fluorine, chlorine and ammonium, which are known to modulate dislocation movement in the ice crystal lattice. Insolation-sensitive microstructure appears to be preserved all the way to the pore close-off, within layers of the summer-to-autumn metamorphism. Like previous authors, we hypothesize that calcium is not the active agent in the reported deformation– calcium correlations.
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Jiang, Yingqi, and Liwei Lin. "A two-stage, self-aligned vertical densification process for as-grown CNT forests in supercapacitor applications." Sensors and Actuators A: Physical 188 (December 2012): 261–67. http://dx.doi.org/10.1016/j.sna.2012.04.012.
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GENERALOV, Viktor P., and Elena M. GENERALOVA. "PROSPECTS OF DEVELOPMENT OF HIGH-RISE BUILDINGS TYPOLOGY FUTURE CITY." Urban construction and architecture 5, no. 1 (February 15, 2015): 13–18. http://dx.doi.org/10.17673/vestnik.2015.01.2.
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The current questions of prospects of modern cities development are viewed in the light of steady growth of population and urbanization connected with enhancement of cities role in social development. The problem of urban densification and the prospectivity of large cities vertical growth are considered. China practice is analyzed because this state is acknowledged global leader in the matter of high-rise building and its achievements can be useful for the Russian Federation. The article concerns activities of the Council on Tall Buildings and Urban Habitat (CTBUH) researching high-rise building. Modern approaches to highrise buildings typology are examined, their main point is defined as mini-city in city.
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Belart, Joaquín M. C., Etienne Berthier, Eyjólfur Magnússon, Leif S. Anderson, Finnur Pálsson, Thorsteinn Thorsteinsson, Ian M. Howat, Guðfinna Aðalgeirsdóttir, Tómas Jóhannesson, and Alexander H. Jarosch. "Winter mass balance of Drangajökull ice cap (NW Iceland) derived from satellite sub-meter stereo images." Cryosphere 11, no. 3 (June 30, 2017): 1501–17. http://dx.doi.org/10.5194/tc-11-1501-2017.
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Abstract. Sub-meter resolution, stereoscopic satellite images allow for the generation of accurate and high-resolution digital elevation models (DEMs) over glaciers and ice caps. Here, repeated stereo images of Drangajökull ice cap (NW Iceland) from Pléiades and WorldView2 (WV2) are combined with in situ estimates of snow density and densification of firn and fresh snow to provide the first estimates of the glacier-wide geodetic winter mass balance obtained from satellite imagery. Statistics in snow- and ice-free areas reveal similar vertical relative accuracy (< 0.5 m) with and without ground control points (GCPs), demonstrating the capability for measuring seasonal snow accumulation. The calculated winter (14 October 2014 to 22 May 2015) mass balance of Drangajökull was 3.33 ± 0.23 m w.e. (meter water equivalent), with ∼ 60 % of the accumulation occurring by February, which is in good agreement with nearby ground observations. On average, the repeated DEMs yield 22 % less elevation change than the length of eight winter snow cores due to (1) the time difference between in situ and satellite observations, (2) firn densification and (3) elevation changes due to ice dynamics. The contributions of these three factors were of similar magnitude. This study demonstrates that seasonal geodetic mass balance can, in many areas, be estimated from sub-meter resolution satellite stereo images.
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Larson, Kristine M., John Wahr, and Peter Kuipers Munneke. "Constraints on snow accumulation and firn density in Greenland using GPS receivers." Journal of Glaciology 61, no. 225 (2015): 101–14. http://dx.doi.org/10.3189/2015jog14j130.
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AbstractData from three continuously operating GPS sites located in the interior of the Greenland ice sheet are analyzed. Traditionally these kinds of GPS installations (where the GPS antenna is placed on a pole deployed into the firn) are used to estimate the local horizontal speed and direction of the ice sheet. However, these data are also sensitive to the vertical displacement of the pole as it moves through the firn layer. A new method developed to measure snow depth variations with reflected GPS signals is applied to these GPS data from Greenland. This method provides a constraint on the vertical distance between the GPS antenna and the surface snow layer. The vertical positions and snow surface heights are then used to assess output from surface accumulation and firn densification models, showing agreement better than 10% at the sites with the longest records. Comparisons between the GPS reflection method and in situ snow sensors at the Dye-2 site show good agreement, capturing the dramatic changes observed in Greenland during the 2012 summer melt season. The geocentric elevation of the snow surface can be inferred by subtracting the snow surface height estimates from the vertical position measurements. It should be possible to use those surface elevation estimates to help validate elevation results obtained from satellite altimetry.
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Kasajima, Y., and T. Johannessen. "Role of cabbeling in water densification in the Greenland Basin." Ocean Science Discussions 5, no. 3 (September 12, 2008): 507–43. http://dx.doi.org/10.5194/osd-5-507-2008.
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Abstract. The contribution of cabbeling mixing to water mass modification in the Greenland Sea was explored from hydrographic observation across the Greenland Basin in summer 2006. Neutral surface was chosen as a reference frame, and the strength of cabbeling mixing was determined by the dianeutral velocity magnitude. Water types in the area were classified into North Atlantic Water (NAW), modified North Atlantic Water (mNAW), water from Barents Sea near Bear Island (BIW), Arctic Intermediate Water (AIW) and Deep Water (DW), and significant cabbeling-induced velocity (>1 m/day) appeared at the interfaces of these water types below the seasonal pycnocline. The mixing between BIW and NAW in the eastern periphery was the most vigorous, where mixing-induced velocity reached 7.5 m/day which accompanied NAW production of 123 m3/day through transformation of BIW. Cabbeling in the Arctic Frontal Zone was found of two types; mixing within NAW in the upper layer and mixing within mNAW in the lower layer with a maximum velocity of 3 m/day. Source waters in the central Greenland Basin were AIW and mNAW and produced a vertical velocity of 4 m/day. In the western part of the Greenland Basin, the areas of active cabbeling were widely separated and each mixing point appeared rather weak, with a maximum velocity of 2.5 m/day. The average density gain in the eastern periphery was 0.003 kg/m3 while it was 0.001 kg/m3 in the other areas, though the impact of cabbeling on the bulk buoyancy change was highest in the western Greenland Sea. The frontal areas occupied approximately 50% of the whole analysis area and the total density gain due to cabbeling mixing in the Greenland Basin as a whole was estimated as 6.7×10−4 kg/m3.
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Eyvazian, Arameh, Hozhabr Mozafari, Faris Tarlochan, and Abdel Magid S. Hamouda. "Numerical and Experimental Investigation on Corrugation Geometry for Metallic Tubes under Lateral Loading." Materials Science Forum 916 (March 2018): 226–31. http://dx.doi.org/10.4028/www.scientific.net/msf.916.226.
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Energy absorption devices are being used to protect structures from severe damages and reduce injury to occupants during accidents. The integrated characteristics of crash absorption devices can be classified as high energy absorption capacity, light-weight, and cost-effective. One of the thin-walled structures which has drawn the attention of scientists is corrugated tube structure. In this paper, the effect of corrugation geometry on the crushing parameters of an aluminum corrugated tube is investigated. In this regard, different elliptical corrugation shapes were deemed and the compression response was numerically evaluated under lateral quasi-static loading. Finally, the crashworthiness parameters were extracted and compared to determine the influence of corrugation shape on the crashworthy response. Our results showed that using vertical elliptical corrugation decrease the densification point. Moreover, there is a gradual enhancement of mean crushing load by moving from the horizontal elliptical corrugations to the vertical ones. Also, by modifying of corrugation shape, the stress variation pattern changes, significantly.
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Richert, Claudia, Yijuan Wu, Murilo Hablitzel, Erica T. Lilleodden, and Norbert Huber. "Image segmentation and analysis for densification mapping of nanoporous gold after nanoindentation." MRS Advances 6, no. 20 (July 14, 2021): 519–23. http://dx.doi.org/10.1557/s43580-021-00099-w.
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AbstractSegmentation of scanning electron microscopy (SEM) images of focused ion beam (FIB) cross-sections through indented regions in nanoporous gold (np-Au) is carried out. A key challenge for image analysis of open porous materials is the appropriate binarization of the pore and gold ligament regions while excluding material lying below the cross-sectional plane. Here, a manual approach to thresholding is compared to global and local approaches. The global thresholding resulted in excessive deviations from the nominal solid fraction, due to a strong gray-scale gradient caused by the tilt angle during imaging and material shadowing. In contrast, the local thresholding approach delivered local solid fractions that were free of global gradients, and delivered a quality comparable to the manual segmentation. The extracted densification profiles vertically below the indenter as well as parallel to the surface showed an exponential-type decay from the indenter tip towards the nominal value of 1 far from the indenter. Graphic abstract
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Shalbafan, Ali, and Heiko Thoemen. "Influence of Pressing Schedule and Adhesive Content on the Rheological Behavior of Wood Fiber-Furnish Mats." Materials 15, no. 4 (February 14, 2022): 1413. http://dx.doi.org/10.3390/ma15041413.
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In this study, for a better understanding of the hot-pressing process, the influence of adhesive content (AC) on various features of a typical pressing schedule for medium-density fiberboard (MDF) production, including fiber mat compressibility, heat transfer during hot-pressing, density profile and board properties, were evaluated. It was found that increasing the AC (urea formaldehyde) leads to faster heat transfer towards the mat’s central plane, mainly due to higher heat release from the adhesive polycondensation reaction. Moreover, the results indicate that the time needed to reach the critical mark of 100 °C in the central plane of the mat depends on the duration of the first densification level (FD). Importantly, the pressure peaks (pmax and p2nd) needed for mat densification are significantly reduced when increasing the AC, which might be attributed to the slippery effect created by the adhesive on the fiber surfaces. The duration of the FD also showed obvious effects on the intermediate density maxima (ρinter) and the core layer density (ρcore). In general, the physical and mechanical properties of MDF panels are significantly impacted by the pressing schedule and AC. All in all, the results of this study are valuable information for refining existing rheological models to improve their accuracy and their ability to simulate the vertical density profile during industrial production.
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Houde, Jean-François, Peter Newberry, and Katja Seim. "Nexus Tax Laws and Economies of Density in E‐Commerce: A Study of Amazon's Fulfillment Center Network." Econometrica 91, no. 1 (2023): 147–90. http://dx.doi.org/10.3982/ecta15265.
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We quantify the distortionary effects of nexus tax laws on Amazon's distribution network investments between 1999 and 2018. We highlight the role of two features of the expansion of Amazon's network: densification of the network of distribution facilities and vertical integration into package sortation. Densification results in a reduction in the cost of shipping orders, but comes at the expense of higher facility operating costs in more expensive areas and lower scale economies of processing shipments. Nexus laws furthermore generate additional sales tax liabilities as the network grows. Combining data on household spending across online and offline retailers with detailed data on Amazon's distribution network, we quantify these trade‐offs through a static model of demand and a dynamic model of investment. Our results suggest that Amazon's expansion led to significant shipping cost savings and facilitated the realization of aggregate economies of scale. We find that abolishing nexus tax laws in favor of a non‐discriminatory tax policy would induce the company to decentralize its network, lowering its shipping costs. Non‐discriminatory taxation would also entail lower revenue, however, as tax‐inclusive prices would rise, resulting in a fall in profit overall. This drop and the decline in consumer welfare from higher taxes together fall short of the increases in tax revenue and rival profit, suggesting that the abolishment of nexus laws would lead to an increase in total welfare.
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Dind, Aleksis, Sophie Lufkin, and Emmanuel Rey. "A Modular Timber Construction System for the Sustainable Vertical Extension of Office Buildings." Designs 2, no. 3 (August 8, 2018): 30. http://dx.doi.org/10.3390/designs2030030.
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Most European cities are facing urban densification issues. In this context, a solution to create usable spaces without additional pressure on land consists in the vertical extension of existing buildings. Given their abundance in the building stock, tertiary buildings offer an important potential. The paper introduces the Working Space project, which aims to develop an innovative, modular and prefabricated timber construction system adapted to the vertical extension of existing office buildings. The dimensions of the system can be adjusted to a great variety of structural grids and allows for any new typological organisation. Based on the principles of bioclimatic architecture, the extension’s envelope provides high-performance insulation, a smart management of passive solar gains, natural ventilation and free cooling, but also offers large surfaces dedicated to photovoltaic energy production and urban biodiversity. The system is made up of eco-friendly, local materials with very low environmental impact. The project’s outcomes are presented at a variety of scales, from urban design to construction details, as well as the outputs of an extensive life cycle assessment including the induced mobility impacts. Finally, the paper introduces a first application of this innovative architectural concept, which is currently being completed in Lausanne, Switzerland.
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Gil-Plazas, Andres-Fernando, Julián-David Rubiano-Buitrago, Luis-Alejandro Boyacá-Mendivelso, and Liz-Karen Herrera-Quintero. "Solid-State and Super Solidus Liquid Phase Sintering of 4340 Steel SLM Powders Shaped by Fused Filament Fabrication." Revista Facultad de Ingeniería 31, no. 60 (May 21, 2022): e13913. http://dx.doi.org/10.19053/01211129.v31.n60.2022.13913.
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4340 steel powders were processed with an additive manufacturing process using the FFF (Fused Filament Fabrication) technique. A composite filament was developed to print samples and study the effect of the bed and nozzle temperatures on its physical and microstructural properties. The printed samples were debinded and sintered by: Solid State (SS) at 1300 °C or SLPS (Supersolidus Liquid Phase Sintering) at 1420 °C. Metallography and scanning electron microscopy (SEM) identified the microstructure and phases. The hardness of the sintered samples was measured with the Vickers method. The SLPS process contributes to better densification and volume contraction; however, it promotes geometrical distortion of the samples compared to the SS samples. The microstructure of the sintered samples consists of ferrite situated in the original austenite grain and bainite. The sintering mechanism significantly influenced the hardness of the samples. Finally, a part was designed, printed, debinded, and sintered with the aim of studying the maximum inclination angle, the minimum vertical and horizontal holes, and the minimum vertical layer thickness, which can be obtained through the whole process.
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Ou, Hui Bin, Mohamed Sahli, Thierry Barrière, and Jean Claude Gelin. "Modeling, Identification and Simulation of the Sintering Stage for Micro-Bi-Material Components." Key Engineering Materials 651-653 (July 2015): 726–31. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.726.
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This paper investigates the numerical simulation of the sintering stage by solid state diffusion during the metal injection molding process for micro-bi-material component based on a thermo-elasto-viscoplastic model. The physical parameters concerning very fine 316L stainless steel and copper powders with high volume loading contents involved in the sintering model have been identified in order to set up finite element simulations. The experimental tests have been carried out in a vertical dilatometer and the identification of the material parameters have been carried out with Matlab® platform software. Then in order to predict the shrinkage and relative density after densification, a solid state diffusion model for the sintering has been implemented in finite element software to perform the simulation of the sintering stage.
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Hadi, Mohamed Saad, and Haider M. Mekkiyah. "The Behavior of the Al-Kadhim Minaret during Earthquakes: A Virtual Study." Journal of Engineering 29, no. 1 (January 1, 2023): 1–13. http://dx.doi.org/10.31026/j.eng.2023.01.01.
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The study focuses on the causes of minaret tilting as well as possible solutions. The major aims of this study are to improve knowledge of historical tall structure stability and rehabilitation operations using the finite element approach to model the soil and minaret (PLAXIS 3D 2020), a platform for computational soil investigation and modeling. The numerical analysis aims to identify stresses, settlement, and deformation of the soil and minaret in various scenarios like Earthquakes, explosions, and winds. The simulation of the problem by the PLAXIS 3D revealed that the greatest lateral displacement computed at the Top Minaret is 5.5 cm, and the greatest vertical movement is calculated to be 3 cm. Seismic settlement is the effect of earthquake shaking, causing densification of soil with lower relative density.
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Guo, Youlin, Xiaocong Cai, and Meixiang Gu. "Bearing Capacity and Deformation of the Tandem Compound Piles Improved Foundation: A Parametric Study." Materials 16, no. 17 (August 22, 2023): 5737. http://dx.doi.org/10.3390/ma16175737.
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The tandem compound piles are a combination of a granular column in the deep section and a concrete pile in the shallow section. This method effectively utilizes the consolidation and densification effects of the granular column, as well as the cementation strength of the concrete material. The granular column acts as a consolidation path, aiding in the densification of the surrounding soil. On the other hand, the concrete pile prevents the bulging deformation that commonly happens in granular columns during field construction. To study the bearing capacity and deformation of the improved foundation with tandem compound piles, a coupled continuum-discrete numerical model was developed in this study. The accuracy of the model was confirmed by comparing its results with experimental measurements. Additionally, a parametric study was conducted, considering three influential factors: (1) cushion thickness and modulus, (2) length, modulus, diameter, and spacing of the tandem compound pile, and (3) soil modulus. The results indicated that reducing the cushion thickness and increasing the cushion modulus allowed the pile to bear more loads. Moreover, increasing the length and modulus of the deep section of the pile reduced deformation and improved the bearing capacity. The pile modulus, however, had a limited effect on enhancing the bearing capacity. It is important to maintain a critical pile spacing of at least twice the pile diameter. Finally, a high modulus of the underlying stratum led to higher vertical and radial stresses in the pile.
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Kitazume, Masaki, Akihiko Takahashi, Kenji Harada, and Naotoshi Shinkawa. "New type sand compaction pile method for densification of liquefiable ground underneath existing structure." Journal of Geo-Engineering Sciences 3, no. 1 (June 8, 2016): 1–13. http://dx.doi.org/10.3233/jgs-150032.
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The 2011 Great East Japan Earthquake caused severe damage to infrastructures due to liquefaction, in which many embankments failed with large settlement and slope failure. Sand Compaction Pile method is one of the typical ground improvement methods to densify the ground by installing compacted sand piles into ground. This method has been often applied to mitigate the liquefaction. However, current SCP method of constructing sand piles in vertical direction is not able to densify ground underneath an existing structure. For applying the method to an existing structure, a new type of SCP method was recently developed where in compacted sand columns can be constructed in any direction. This paper briefly introduces the new type of SCP method and the effectiveness of local densification by numerical analysis. In this manuscript, a series of numerical analyses were conducted to evaluate the effect of shape and location of SCP improved zone on the dynamic response of embankment. This paper describes the numerical analyses as well as the development, machinery and procedure of the technique, and emphasizes the uniqueness and effectiveness of the technique for preventing liquefaction for new and existing structures.
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Leif Kullman. "Recent spruce (Picea abies) treeline ecotonal progression since the late1980s in the Swedish Scandes-a repeat photographic narration and analysis." International Journal of Science and Research Archive 4, no. 1 (November 30, 2021): 067–85. http://dx.doi.org/10.30574/ijsra.2021.4.1.0189.
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This study reports a case of climate-mediated transformation and physiognomic progression of the Norway spruce (Picea abies) treeline ecotone since the mid-1990s in the Swedish Scandes. The methods include repeat photography and foliation estimates of old-established clonal spruces. An air and soil temperature nadir by the 1980s had caused extensive needle and shoot mortality, evident at the landscape-scale. Subsequent winter and summer temperature rises induced a striking canopy recovery, including densification and vertical growth. Release from low soil temperature stress appears as instrumental for canopy progression and shift from stunted growth to erect tree forms. Seed-based regeneration of new individuals has been virtually nil and the ecotone appears to be spatially stable. Ongoing ecotonal shifts has the character of growth form transformations in accordance with climatic conjunctures.
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Prakash, Aniket, Diksha, and Amit Kumar. "Measuring Vertical Urban Growth of Patna Urban Agglomeration Using Persistent Scatterer Interferometry SAR (PSInSAR) Remote Sensing." Remote Sensing 15, no. 14 (July 24, 2023): 3687. http://dx.doi.org/10.3390/rs15143687.
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In the present study, the vertical and horizontal growth of Patna Urban Agglomeration was evaluated using the Persistent Scatterer Interferometry Synthetic Aperture Radar (PSInSAR) technique during 2015–2018. The vertical urban growth assessment of the city landscape was assessed using microwave time series (30 temporal) datasets of Single Look Complex (SLC) Sentinel-1A interferometric Synthetic Aperture Radar using SARPROZ software (ver. 2020). This study demonstrated that peripheral city regions experienced higher vertical growth (~4 m year−1) compared to the city core regions, owing to higher urban development opportunities leading to significant land use alterations, the development of high-rise buildings, and infrastructural development. While the city core of Patna observed an infill and densification process, as it was already saturated and highly densified. The rapidly urbanizing city in the developing region witnessed a considerable horizontal urban expansion as estimated through the normalized difference index for built-up areas (NDIB) and speckle divergence (SD) using optical Sentinel 2A and microwave Sentinel-1A ground range detected (GRD) satellite data, respectively. The speckle divergence-based method exhibited high urban growth (net growth of 11.28 km2) with moderate urban infill during 2015–2018 and reported a higher accuracy as compared to NDIB. This study highlights the application of SAR remote sensing for precise urban area delineation and temporal monitoring of urban growth considering horizontal and vertical expansion through processing a long series of InSAR datasets that provide valuable information for informed decision-making and support the development of sustainable and resilient cities.
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Hulbe, Christina L., and Ian M. Whillans. "A method for determining ice-thickness change at remote locations using GPS." Annals of Glaciology 20 (1994): 263–68. http://dx.doi.org/10.3189/1994aog20-1-263-268.
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Ice-thickness changes at remote locations on ice sheets can be determined by means of precise Global Positioning System (GPS) surveys with interferometric solutions. Remote sites are precisely surveyed relative to GPS receivers on rock. Repeat observations of the position of a remote site provide its vertical velocity. The difference between this velocity and accumulation rate is an indicator of change in ice-sheet thickness. Allowance must be made for the movement of survey markers due to firn compaction and down-slope ice motion, To allow for firn compaction, very long- poles arc placed to a sufficient depth in the firn that the densification rate can be considered steady. This assumption may be tested by measurements with poles set to different depths. An analysis of errors in pilot studies indicates that the limit to precision is the determination of accumulation rate.