Journal articles on the topic 'Interaction avalanche and structure'
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Naaim, Mohamed, Thierry Faug, Florence Naaim, and Nicolas Eckert. "Return period calculation and passive structure design at the Taconnaz avalanche path, France." Annals of Glaciology 51, no. 54 (2010): 89–97. http://dx.doi.org/10.3189/172756410791386517.
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AbstractThis paper aims to show how recent knowledge developed in the field of avalanche research can be used for a real case study, the Taconnaz avalanche path, where passive structures already existed but had to be improved. First a morphological analysis of the site is done and historical data are analysed. Second, each recorded event is back-calculated using a numerical model of dense-flow avalanches. For each surveyed avalanche, parameters at the entry of the runout zone upstream of the defence structures are defined. Third, a statistical analysis of these parameters allows characterization of 100 year return period events. Fourth, physical and numerical models of dense avalanches interacting with defence structures are combined in order to design the most effective passive structure able to contain the reference scenarios. Finally, physical and numerical modelling of the interaction between the powder avalanche and the designed defence structure is performed, to show that the proposed improvements do not increase the residual risk due to the powder part in areas downstream of the defence structures.
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Domaas, U., C. B. Harbitz, and H. Bakkehøi. "The EU CADZIE database for extreme and deflected snow avalanches." Natural Hazards and Earth System Sciences 2, no. 3/4 (December 31, 2002): 227–38. http://dx.doi.org/10.5194/nhess-2-227-2002.
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Abstract. The EU programme CADZIE (Catastrophic Avalanches: Defence Structures and Zoning in Europe), was established after the catastrophic 1999 avalanche winter in Europe. The overall objective of the programme is improved snow avalanche risk management by: (1) improved avalanche hazard zoning by computational models; and (2) improved understanding of the interaction between defence structures and avalanches. One contribution to meet the objectives is a database of well-documented extreme or deflected avalanche events in the six countries of the partners of the programme. The database contains observational, topographical and meteorological snow avalanche data with reliability, as well as references, copyrights, etc., all in a convenient framework based on common formats. The structure, contents, and potential use of the database are described. Example calculations of extreme and deflected events made by the NGI user interface "SKRED", for practical use of avalanche computational models, present applications of the database. Finally, further development of the database and of the computational models to meet the future needs in avalanche hazard zoning is proposed.
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Nicot, F., and M. Gay. "Modelling of interaction between a snow mantle and a flexible structure using a discrete element method." Natural Hazards and Earth System Sciences 2, no. 3/4 (December 31, 2002): 163–67. http://dx.doi.org/10.5194/nhess-2-163-2002.
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Abstract. The search of improvement of protective techniques against natural phenomena such as snow avalanches continues to use classic methods for calculating flexible structures. This paper deals with a new method to design avalanche protection nets. This method is based on a coupled analysis of both net structure and snow mantle by using a Discrete Element Method. This has led to the development of computational software so that avalanche nets can be easily designed. This tool gives the evolution of the forces acting in several parts of the work as a function of the snow situation.
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Margreth, Stefan, and Walter J. Ammann. "Hazard scenarios for avalanche actions on bridges." Annals of Glaciology 38 (2004): 89–96. http://dx.doi.org/10.3189/172756404781814951.
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AbstractEngineers require impact scenarios when developing hazard mitigation strategies to protect structures against snow avalanches. Since direct measurements of avalanche impacts on large obstacles are rare, the documentation and post-event analysis of avalanche damages is essential to understand the interaction of avalanches with obstacles. The objective of this paper is to develop hazard scenarios for avalanche actions on bridges, based on a case study of a well-documented avalanche event. The 40 m long pre-stressed road bridge Ri di Rialp in the Swiss Alps collapsed after being struck by a dense-flow avalanche in 1998. The post-event analysis shows that the controlling hazard scenario was an inclined avalanche impact, not a horizontal impact as one would assume given the topographical situation. Using a failure analysis, an impact angle of 40° and a minimal impact pressure of 172 kN m−2 were found. Finally the insights are summarized so that engineers can apply the results when designing a bridge at risk from avalanches.
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Feistl, Thomas, Peter Bebi, Michaela Teich, Yves Bühler, Marc Christen, Kurosch Thuro, and Perry Bartelt. "Observations and modeling of the braking effect of forests on small and medium avalanches." Journal of Glaciology 60, no. 219 (2014): 124–38. http://dx.doi.org/10.3189/2014jog13j055.
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AbstractA long-standing problem in avalanche science is to understand how forests stop avalanches. In this paper we quantify the effect of forests on small and medium avalanches, crucial for road and skirun safety. We performed field studies on seven avalanches where trees affected the runout. We gathered information concerning the release zone location and dimension, deposition patterns and heights, runout distance and forest structure. In these studies the trees were not destroyed, but acted as rigid obstacles. Wedge-like depositions formed behind (1) individual tree stems, (2) dense tree groups and (3) young trees with low-lying branches. Using the observations as a guide, we developed a one-parameter function to extract momentum corresponding to the stopped mass from the avalanche. The function was implemented in a depth-averaged avalanche dynamics model and used to predict the observed runout distances and mean deposition heights for the seven case studies. The approach differs from existing forest interaction models, which modify avalanche friction to account for tree breakage and debris entrainment. Our results underscore the importance of forests in mitigating the danger from small-to-medium avalanches.
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Jaedicke, Christian, Florence Naaim-Bouvet, and Matthias Granig. "Wind-tunnel study of snowdrift around avalanche defence structures." Annals of Glaciology 38 (2004): 325–30. http://dx.doi.org/10.3189/172756404781814799.
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AbstractAvalanche defence structures such as retarding dams and breaking mounds are widely used to protect residential areas and other kinds of infrastructure. The effect of the defence structures depends largely on their effective height relative to the velocity, volume and flow depth of the avalanche. Snow depositions from earlier avalanches as well as from drifting snow can significantly alter the effective height of defence structures. Different designs of avalanche-breaking mounds and retarding dams were tested in the Cemagref (Grenoble, France) wind tunnel for their effect on drifting snow. Examples included dams and mounds of different sizes and heights. The models were tested in a wind tunnel with sand particles subjected to different wind directions. The resulting depositions were scanned with a laser system to obtain a three-dimensional picture of the accumulation pattern. The results show that the accumulated snow varies widely with the design of the structure for a given wind direction. Most snow is accumulated around narrow mounds, with least accumulation observed around mounds covering a smaller relative area of the avalanche path. The data obtained can be used to study the effect of the depositions on the retarding effect of the avalanche defence structures. However, because the similarity criteria for studying the interaction between structures and saltating particles in a wind tunnel cannot be met, the transfer of the results to reality must be performed with caution.
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Naaim-Bouvet, F., M. Naaim, M. Bacher, and L. Heiligenstein. "Physical modelling of the interaction between powder avalanches and defence structures." Natural Hazards and Earth System Sciences 2, no. 3/4 (December 31, 2002): 193–202. http://dx.doi.org/10.5194/nhess-2-193-2002.
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Abstract. In order to better understand the interaction between powder snow avalanches and defence structures, we carried out physical experiments on small-scale models. The powder snow avalanche was simulated by a heavy salt solution in a water tank. Quasi two-dimensional and three-dimensional experiments were carried out with different catching dam heights. For the reference avalanche, the velocity just behind the nose in the head was greater than the front velocity. For the 2-D configuration, the ratio Umax/Ufront was as high as 1.6, but it depends on the height. For the 3-D configuration, this ratio differed slightly and was even greater (up to 1.8). The vertical velocity rose to 106% of the front velocity for the 3-D simulation and 74% for the 2-D simulation. The reduction in front velocity due to the presence of dams was an increasing function of the dam height. But this reduction depended on topography: dams were more effective on an open slope avalanche (3-D configuration). The ratio Umax/Ufront was an increasing function of the dam’s height and reached a value of 1.9. The obstacle led to a reduction in vertical velocity downstream of the vortex zone.
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Casteller, Alejandro, Thomas Häfelfinger, Erika Cortés Donoso, Karen Podvin, Dominik Kulakowski, and Peter Bebi. "Assessing the interaction between mountain forests and snow avalanches at Nevados de Chillán, Chile and its implications for ecosystem-based disaster risk reduction." Natural Hazards and Earth System Sciences 18, no. 4 (April 18, 2018): 1173–86. http://dx.doi.org/10.5194/nhess-18-1173-2018.
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Abstract. Gravitational natural hazards such as snow avalanches, rockfalls, shallow landslides and volcanic activity represent a risk to mountain communities around the world. In particular, where documentary records about these processes are rare, decisions on risk management and land-use planning have to be based on a variety of other sources including vegetation, tree-ring data and natural hazard process models. We used a combination of these methods in order to evaluate dynamics of natural hazards with a focus on snow avalanches at Valle Las Trancas, in the Biobío region in Chile. Along this valley, natural hazards threaten not only the local human population, but also the numerous tourists attracted by outdoor recreational activities. Given the regional scarcity of documentary records, tree-ring methods were applied in order to reconstruct the local history of snow avalanches and debris flow events, which are the most important weather-related processes at respective tracks. A recent version of the model Rapid Mass MovementS (RAMMS), which includes influences of forest structure, was used to calculate different avalanche parameters such as runout distances and maximum pressures, taking into consideration the presence or absence of forest along the tracks as well as different modeled return periods. Our results show that local Nothofagus broadleaf forests contribute to a reduction of avalanche runout distances as well as impact pressure on present infrastructure, thus constituting a valuable ecosystem disaster risk reduction measure that can substitute or complement other traditional measures such as snow sheds.
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Bao, Yiding, Jianping Chen, Weifeng Zhang, Yuchao Li, Zhihai Li, and Ni Du. "Effect of the Fracturing Degree of the Source Rock on Rock Avalanche River-Blocking Behavior Based on the Coupled Eulerian-Lagrangian Technique." Minerals 12, no. 7 (July 18, 2022): 901. http://dx.doi.org/10.3390/min12070901.
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In this study, the effect of the fracturing degree of the source rock on rock avalanche river-blocking behavior was investigated. The study included the analysis of mass movement behavior, impulse wave behavior, and the formation of landslide dams. The study included a series of simulations of rock avalanche river-blocking based on the coupled Eulerian-Lagrangian (CEL) technique. Prior to the simulation, a water column collapse model was applied to validate the use of the CEL technique on fluid-structure interaction, and to calibrate the material parameters. The source rock in the rock avalanche simulation was cut by different groups of structural planes, with the number of 0 × 0 × 0, 1 × 1 × 1, 4 × 4 × 4, 9 × 9 × 9, 14 × 14 × 14, 19 × 19 × 19 in each dimension, respectively, to represent different fracturing degrees, on the premise of the same volume and shape of the source rock. The simulation results showed that the sliding mass exhibited structure stabilization, such that the structure of the sliding mass gradually stabilized to a steady status over time, in the mass movement process. The structure stabilization made the center of the sliding mass constantly decrease, and provided a higher speed of movement for the rock avalanches with higher fracturing degrees of the source rock. As for the impulse wave behavior, with the increase in the fracturing degree of the source rock, the maximum kinetic energy of the water decreased, and the maximum height and propagation speed of the impulse waves decreased, which indicated that the maximum height and the propagation speed of the impulse waves were positively correlated with the maximum kinetic energy of the water. In regard to the formation of the landslide dams, when the fracturing degree of the source rock was low, the shape of the landslide dam was very different. With the increase of the fracturing degree of the source rock, the shapes of the landslide dams stabilized, and varied slightly after the fracturing degree of the source rock reached a threshold value.
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Kriz, Karel. "ALBINA The White Goddess – Mapping and Communicating Avalanche Risk in the European Alps." Abstracts of the ICA 1 (July 15, 2019): 1. http://dx.doi.org/10.5194/ica-abs-1-191-2019.
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<p><strong>Abstract.</strong> With the increasing importance of communication in the context of risk management and disaster prevention in mountainous environments, the demand for adequate communication channels and cartographic representations is constantly rising. In particular, the presentation of a broad spectrum of geospatial topics such as avalanche awareness requires innovative cartographic methods and approaches that go beyond standard cartographic depiction procedures.</p><p>ALBINA is such a project that addresses this proposition. It embraces risk management with cartographic communication methods and stands for “The White Goddess” an allusion to snow avalanches. This cooperation project has the goal to publish a joint, multilingual avalanche bulletin in the entire European region of Tyrol, South Tyrol and Trentino. The aim is to inform the public daily about the avalanche situation as well as to communicate avalanche related information in an efficient and profound way. An online portal is currently being developed as part of an Interreg V-A Italy-Austria project in collaboration between the University of Vienna, the EVTZ Europaregion, the Austrian Avalanche Warning Service of Tyrol as well as the Italian Avalanche Warning Services of South Tyrol and Trentino. The developed communication structures promote and facilitate the exchange of spatial-temporal information between experts of neighboring regions as well as the public in a multi-lingual environment. The framework is supported by a software system that handles and visualizes meteorological data, observations, snow profiles and avalanche events of the entire region with a strong focus on cartographic communication. It furthermore offers the possibility to enter and manipulate the avalanche bulletin in a standardized way in order to optimize the exchange of information between the avalanche experts on duty.</p><p>In order to foster the efforts in avalanche awareness and communication three conceptual cornerstones have been identified according to international avalanche warning standards: (1) avalanche danger assessment and forecasting production, (2) timing and validity of publication and (3) effective geo-communication. Based on this alignment the international ALBINA project was launched to showcase the ability and strength of such an approach. This presentation will primarily focus on effective geo-communication clarifying the general framework as well as the communication structures and workflow within the overall system. Thereby explaining the methods and interaction between the available real-time data, the technical infrastructure, the human resources as well as the geo-communicational aspects of the system. Thereafter the individual cornerstones of the system will be discussed. These consist of various services dealing with the input and administration of avalanche relevant information, geodata processing and provision, map production and dissemination, meteorological map and diagram manipulation and creation as well as the design and conception of the frontend web-interface. Finally, the current state of the system will be presented exemplifying the geo-communicational procedures and methods.</p>
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Nicot, F., M. Gay, and J. M. Tacnet. "Interaction between a snow mantel and a flexible structure: a new method to design avalanche nets." Cold Regions Science and Technology 34, no. 2 (April 2002): 67–84. http://dx.doi.org/10.1016/s0165-232x(01)00052-0.
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FAVIER, PHILOMÈNE, NICOLAS ECKERT, THIERRY FAUG, DAVID BERTRAND, and MOHAMED NAAIM. "Avalanche risk evaluation and protective dam optimal design using extreme value statistics." Journal of Glaciology 62, no. 234 (May 19, 2016): 725–49. http://dx.doi.org/10.1017/jog.2016.64.
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ABSTRACTIn snow avalanche long-term forecasting, existing risk-based methods remain difficult to use in a real engineering context. In this work, we expand a quasi analytical decisional model to obtain simple formulae to quantify risk and to perform the optimal design of an avalanche dam in a quick and efficient way. Specifically, the exponential runout model is replaced by the Generalized Pareto distribution (GPD), which has theoretical justifications that promote its use for modelling the different possible runout tail behaviours. Regarding the defence structure/flow interaction, a simple law based on kinetic energy dissipation is compared with a law based on the volume stored upstream of the dam, whose flexibility allows us to cope with various types of snow. We show how a detailed sensitivity study can be conducted, leading to intervals and bounds for risk estimates and optimal design values. Application to a typical case study from the French Alps, highlights potential operational difficulties and how they can be tackled. For instance, the highest sensitivity to the runout tail type and interaction law is found at abscissas of legal importance for hazard zoning (return periods of 10–1000 a), a crucial result for practical purposes.
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Grishnyaev, Evgeny, Aleksandr Dolgov, and Sergey Polosatkin. "The Computer Programm for Statistical Modelling of Fast Neutrons Scattering is Cryogenic Detector of Weakly Interacting Particles." Siberian Journal of Physics 8, no. 3 (October 1, 2013): 39–46. http://dx.doi.org/10.54362/1818-7919-2013-8-3-39-46.
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The paper describes «Scattronix» code designed for modeling of recoiling nuclei spectra in cryogenic avalanche dark matter detector being calibrated with monoenergetic flow of neutrons. «Scattronix» is the code for direct Monte-Carlo modeling of fast neutrons movement in the active media of detector. The features of the task being solved (rare collisions, elastic scattering domination) allow significant simplification of code structure and consequent performance improvement in comparison with conventional codes for neutron-media interaction modeling. Physical basics of neutron scattering on 40Ar nuclei are briefly considered. Algorithm implemented in the code is described. An example of modeled spectra is given and compared with analytical estimation of spectral line width
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WIESE, MAREIKE, and MARTIN SCHNEEBELI. "Early-stage interaction between settlement and temperature-gradient metamorphism." Journal of Glaciology 63, no. 240 (July 24, 2017): 652–62. http://dx.doi.org/10.1017/jog.2017.31.
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ABSTRACTSnow metamorphism and settlement change the microstructure of a snowpack simultaneously. Past experiments investigated snow deformation under isothermal conditions. In nature, temperature gradient metamorphism and settlement often occur together. We investigated snow settlement in the first days after the onset of temperature-gradient metamorphism in laboratory experiments by means of in-situ time-lapse micro-computed tomography. We imposed temperature gradients of up to 95 K m−1 on samples of rounded snow with a density of ~230 kg m−3 and induced settlement by applying 1.7 kPa stress with a passive load on the samples simultaneously. We found that snow settled about half as fast when a temperature gradient was present, compared with isothermal conditions. The change in specific surface area after 4 days caused by temperature-gradient metamorphism was only a few percent. The viscosity evolution correlated with the amount of the temperature gradient. Finite element simulations of the snow samples revealed that stress-bearing chains had developed in the snow structure, causing the large increase in viscosity. We could show that a small change in microstructure caused a large change in the mechanical properties. This explains the difficulty of predicting snow mechanical properties in applications such as firn compaction or snow avalanche formation.
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Mast, Carter M., Pedro Arduino, Gregory R. Miller, and Peter Mackenzie-Helnwein. "Avalanche and landslide simulation using the material point method: flow dynamics and force interaction with structures." Computational Geosciences 18, no. 5 (July 31, 2014): 817–30. http://dx.doi.org/10.1007/s10596-014-9428-9.
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Choi, Minjun J., Hogun Jhang, Jae-Min Kwon, Jinil Chung, Minho Woo, Lei Qi, Sehoon Ko, et al. "Experimental observation of the non-diffusive avalanche-like electron heat transport events and their dynamical interaction with the shear flow structure." Nuclear Fusion 59, no. 8 (June 27, 2019): 086027. http://dx.doi.org/10.1088/1741-4326/ab247d.
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Naaim-Bouvet, Florence, Mohamed Naaim, and Thierry Faug. "Dense and powder avalanches: momentumreduction generated by a dam." Annals of Glaciology 38 (2004): 373–78. http://dx.doi.org/10.3189/172756404781815185.
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AbstractPassive protection structures reduce avalanche run-out distance and hence the potential damages brought about by an avalanche, by reducing its velocity and mass. This paper starts with a summary of the main existing results on interactions between snow avalanches and dams. In the case of dense avalanches, the effects of dams are re-examined and previous results are theoretically justified. For a powder-snow avalanche a dam has two primary effects. The momentum is reduced by the retarding force upstream of the dam and when the jet collides with the ground after the dam. Entrainment of air during the jet reduces its velocity since the mass increases. For a dense avalanche, there is a retarding force upstream of the dam and when the jet collides with the ground, but there is no significant effect of air entrainment. There is, however, deposition of snow which reduces the momentum of the avalanche without affecting the velocity. The reduction of the volume due to deposition reduces the spreading length and therefore the run-out distance of the avalanche. Downstream of the obstacle, the avalanche flow is regarded as an airborne jet. A comparative study shows that density and ambient-fluid entrainment effects are significant for gravity currents, powder and dense snow avalanches whereas they are negligible in granular flows.
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Ashwood, Wesley, and Oldrich Hungr. "Estimating total resisting force in flexible barrier impacted by a granular avalanche using physical and numerical modeling." Canadian Geotechnical Journal 53, no. 10 (October 2016): 1700–1717. http://dx.doi.org/10.1139/cgj-2015-0481.
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Flexible barriers are a promising tool for protection against extremely rapid landslides such as debris flow and debris avalanches. With landslide impacts of any size, the total force induced within the barrier and transferred to the anchorage is a fundamental question to design. Current practice limits the investigation to flow parameters, neglecting the behavior of the structure, which can vary significantly. This paper describes steps taken to quantify the total force induced within a flexible barrier. It describes laboratory experiments of dry granular flow against rigid and flexible barriers with observations of resisting force and other filling processes that provide an understanding of the behavior and possible flow–structure interaction for larger scale rapid landslides. Results from the experiments suggest that for granular flows with high discharge the current practice sufficiently quantifies the total force, and for those with lower discharge, the total force is better characterized by active lateral earth pressure calculations. Test results were also used to validate an adaptation to an existing depth-integrated numerical model for landslide mobility to quantify the total force. This model was then used to estimate the resisting forces induced within a full-scale flexible barrier impacted by a controlled debris flow.
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Moretti, S., S. Cuomo, and L. Frigo. "Finite Difference Modelling of Deformable Geosynthetics-Reinforced Barriers (DGRB) under the dynamic impact of debris avalanches." IOP Conference Series: Materials Science and Engineering 1260, no. 1 (October 1, 2022): 012043. http://dx.doi.org/10.1088/1757-899x/1260/1/012043.
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Abstract The behaviour of Deformable Geosynthetics-Reinforced Barrier (DGRB) is investigated with reference to the dynamic impact of debris avalanches. The aim of these barriers is to protect life of inhabitants and reduce the threat for the exposed structures. A Finite Difference Method code (FLAC, Itasca) is used and the dynamic impact is simulated as an external pressure applied over time to the barrier. The peak lateral pressure exerted by a debris avalanche is evaluated by a literature formulation including a flow-height dependent static component and a flow-velocity dependent dynamic component. Real values of height and velocity of debris avalanches are taken from previous research works. The trend of the pressure during the impact is obtained from the landslide volume and the impulse theorem. The DGRBs are composed of: i) coarse-grained material, ii) bidirectional PET geogrids; iii) external formwork. The soil-geosynthetics contact is simulated through a frictional interface. The several components used in the wrap-around technique are simulated following two different schematizations and the differences between them are highlighted. The used mathematical formulation allows reproducing the impacted barrier both in small and large displacement cases. The local and global displacements of the barrier, its failure mechanisms and the soil-geogrid interaction inside the barrier are investigated. The results outline the differences between the two ways of modelling the wrap-around technique. In particular, the computed global displacements are comparable in the two computational schemes while the simulated stress-strain responses of the structural elements are somehow different.
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THORNTON, A. R., and J. M. N. T. GRAY. "Breaking size segregation waves and particle recirculation in granular avalanches." Journal of Fluid Mechanics 596 (January 17, 2008): 261–84. http://dx.doi.org/10.1017/s0022112007009445.
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Particle-size segregation is a common feature of dense gravity-driven granular free-surface flows, where sliding and frictional grain–grain interactions dominate. Provided that the diameter ratio of the particles is not too large, the grains segregate by a process called kinetic sieving, which, on average, causes the large particles to rise to the surface and the small grains to sink to the base of the avalanche. When the flowing layer is brought to rest this stratification is often preserved in the deposit and is known by geologists as inverse grading. Idealized experiments with bi-disperse mixtures of differently sized grains have shown that inverse grading can be extremely sharp on rough beds at low inclination angles, and may be modelled as a concentration jump or shock. Several authors have developed hyperbolic conservation laws for segregation that naturally lead to a perfectly inversely graded state, with a pure phase of coarse particles separated from a pure phase of fines below, by a sharp concentration jump. A generic feature of these models is that monotonically decreasing sections of this concentration shock steepen and eventually break when the layer is sheared. In this paper, we investigate the structure of the subsequent breaking, which is important for large-particle recirculation at the bouldery margins of debris flows and for fingering instabilities of dry granular flows. We develop an exact quasi-steady travelling wave solution for the structure of the breaking/recirculation zone, which consists of two shocks and two expansion fans that are arranged in a ‘lens’-like structure. A high-resolution shock-capturing numerical scheme is used to investigate the temporal evolution of a linearly decreasing shock towards a steady-state lens, as well as the interaction of two recirculation zones that travel at different speeds and eventually coalesce to form a single zone. Movies are available with the online version of the paper.
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Maurya, S. K., S. Roy Chowdhury, Saibal Ray, and B. Dayanandan. "Study of charged compact stars with class 1 metric under general relativity." Canadian Journal of Physics 97, no. 12 (December 2019): 1323–31. http://dx.doi.org/10.1139/cjp-2018-0560.
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In the present paper we study compact stars under the background of Einstein–Maxwell space–time, where the 4-dimensional spherically symmetric space–time of class 1 along with the Karmarkar condition has been adopted. The investigations, via the set of exact solutions, show several important results, such as (i) the value of density on the surface is finite; (ii) due to the presence of the electric field, the outer surface or the crust region can be considered to be made of electron cloud; (iii) the charge increases rapidly after crossing a certain cutoff region (r/R ≈ 0.3); and (iv) the avalanche of charge has a possible interaction with the particles that are away from the center. As the stellar structure supports all the physical tests performed on it, therefore the overall observation is that the model provides a physically viable and stable compact star.
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de' Michieli Vitturi, Mattia, Tomaso Esposti Ongaro, Giacomo Lari, and Alvaro Aravena. "IMEX_SfloW2D 1.0: a depth-averaged numerical flow model for pyroclastic avalanches." Geoscientific Model Development 12, no. 1 (February 1, 2019): 581–95. http://dx.doi.org/10.5194/gmd-12-581-2019.
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Abstract. Pyroclastic avalanches are a type of granular flow generated at active volcanoes by different mechanisms, including the collapse of steep pyroclastic deposits (e.g., scoria and ash cones), fountaining during moderately explosive eruptions, and crumbling and gravitational collapse of lava domes. They represent end-members of gravity-driven pyroclastic flows characterized by relatively small volumes (less than about 1 Mm3) and relatively thin (1–10 m) layers at high particle concentration (10–50 vol %), manifesting strong topographic control. The simulation of their dynamics and mapping of their hazards pose several different problems to researchers and practitioners, mostly due to the complex and still poorly understood rheology of the polydisperse granular mixture and to the interaction with the complex natural three-dimensional topography, which often causes rapid rheological changes. In this paper, we present IMEX_SfloW2D, a depth-averaged flow model describing the granular mixture as a single-phase granular fluid. The model is formulated in absolute Cartesian coordinates (whereby the fluid flow equations are integrated along the direction of gravity) and can be solved over a topography described by a digital elevation model. The numerical discretization and solution algorithms are formulated to allow for a robust description of wet–dry conditions (thus allowing us to accurately track the front propagation) and an implicit solution to the nonlinear friction terms. Owing to these features, the model is able to reproduce steady solutions, such as the triggering and stopping phases of the flow, without the need for empirical conditions. Benchmark cases are discussed to verify the numerical code implementation and to demonstrate the main features of the new model. A preliminary application to the simulation of the 11 February pyroclastic avalanche at the Etna volcano (Italy) is finally presented. In the present formulation, a simple semi-empirical friction model (Voellmy–Salm rheology) is implemented. However, the modular structure of the code facilitates the implementation of more specific and calibrated rheological models for pyroclastic avalanches.
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Streltsov, Victor A., and Nobuo Ishizawa. "Synchrotron X-ray study of the electron density in RFeO3 (R = Nd, Dy)." Acta Crystallographica Section B Structural Science 55, no. 1 (February 1, 1999): 1–7. http://dx.doi.org/10.1107/s0108768198005400.
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Structure factors for small hydrothermally grown orthorhombic neodymium and dysprosium iron oxides RFeO3 (R = Nd, Dy) were measured with focused λ = 0.84 Å synchrotron radiation using a fast avalanche photodiode (APD) counter. Higher symmetry in the deformation electron density (Δρ) maps reflects the coordination of the magnetic atoms in the structure and implies that Δρ is sensitive to the cation–cation magnetic interactions. Within a given compound the local Δρ topographies around the R and Fe atoms are similar, but differ markedly between compounds. The difference in Δρ near the Nd and Dy atoms is associated with the different type of spin reorientation transitions in these compounds. The R–Fe magnetic interactions determine the magnetic phase transitions and consequently affect the electron distribution. Synchrotron radiation diffraction imaging of the electron density provides an additional tool for probing the magnetic properties of materials.
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Espinal-Enríquez, Jesús, Daniel González-Terán, and Enrique Hernández-Lemus. "The Transcriptional Network Structure of a Myeloid Cell: A Computational Approach." International Journal of Genomics 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/4858173.
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Understanding the general principles underlying genetic regulation in eukaryotes is an incomplete and challenging endeavor. The lack of experimental information regarding the regulation of the whole set of transcription factors and their targets in different cell types is one of the main reasons to this incompleteness. So far, there is a small set of curated known interactions between transcription factors and their downstream genes. Here, we built a transcription factor network for human monocytic THP-1 myeloid cells based on the experimentally curated FANTOM4 database where nodes are genes and the experimental interactions correspond to links. We present the topological parameters which define the network as well as some global structural features and introduce a relative inuence parameter to quantify the relevance of a transcription factor in the context of induction of a phenotype. Genes like ZHX2, ADNP, or SMAD6 seem to be highly regulated to avoid an avalanche transcription event. We compare these results with those of RegulonDB, a highly curated transcriptional network for the prokaryotic organism E. coli, finding similarities between general hallmarks on both transcriptional programs. We believe that an approach, such as the one shown here, could help to understand the one regulation of transcription in eukaryotic cells.
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Bebi, Peter, Michaela Teich, Frank Hagedorn, Natalie Zurbriggen, Sibyl Hanna Brunner, and Adrienne Grêt-Regamey. "Veränderung von Wald und Waldleistungen in der Landschaft Davos im Zuge des Klimawandels." Schweizerische Zeitschrift fur Forstwesen 163, no. 12 (December 1, 2012): 493–501. http://dx.doi.org/10.3188/szf.2012.0493.
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Changes in forest cover and ecosystem services in Davos under climate change The effects of climate change on forests of Davos were examined with field experiments near treeline, analyses of avalanche-forest interactions and with spatially explicit models for the valuation of ecosystem services. Experimental trees at the Stillberg research site showed species-specific responses to elevated CO2 and soil warming. Growth and mortality of the trees planted in the year 1975 were strongly driven by the duration of snow cover and microtopography. Together with other field studies in the region this suggests that during the next decades the treeline will rise only slowly and mainly on favorable microsites. Avalanche protection will also in future be the most important forest service in Davos, although critical weather and snow conditions for forest avalanches show a decreasing trend over the last 40 years. The density of forest structures is likely to further increase with potential positive effects on avalanche protection. Decreases of the protective effect against avalanches may however occur by an increase of natural disturbances such as fires or bark beetle outbreaks. Quantification and overlay of five selected ecosystem services (avalanche protection, recreation, CO2 sequestration and storage, habitats of capercaillie, timber production) suggest in general an increase in the value of most considered ecosystem services.
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Gozdur, Roman. "Study of Quasi-Static Magnetization with the Random-Field Ising Model." Algorithms 13, no. 6 (May 29, 2020): 134. http://dx.doi.org/10.3390/a13060134.
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The topic of this paper is modeling based on Hamiltonian spin interactions. Preliminary studies on the identification of quasi-static magnetizing field in a magnetic system were presented. The random-field Ising model was then used to simulate the simplified ferromagnetic structure. The validation of algorithms and simulation tests were carried out for the 2D and the 3D model spaces containing at least 106 unit cells. The research showed that the response of a slowly driven magnetic system did not depend on the external field sweep rate. Changes in the spatial magnetization of the lattice were very similar below a certain rate of the external field change known as the quasi-static boundary. The observed differences in obtained magnetization curves under quasi-static conditions stemmed from the random nature of the molecular field and the avalanche-like magnetization process
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Berthet-Rambaud, Philippe, Ali Limam, Djebar Baroudi, Emmanuel Thibert, and Jean-Michel Taillandier. "Characterization of avalanche loading on impacted structures: a new approach based on inverse analysis." Journal of Glaciology 54, no. 185 (2008): 324–32. http://dx.doi.org/10.3189/002214308784886090.
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AbstractExperiments have been conducted on the French full-scale experimental site at Lautaret pass to improve our understanding of the action of snow avalanches on obstacles. The ultimate objective is to provide realistic pressure distribution models suitable for use in civil engineering design and to eliminate the restrictive assumptions currently used in this field. We focus on the feasibility of using the inverse method to quantify the action of the avalanche from its effects on realistic structures rather than from sensors placed directly in the flow. This approach takes into account the interactions between the flow and the obstacle and ensures that the result is effectively the action experienced by the obstacle. The inverse analysis procedure is developed and validated using both numerical and laboratory tests. In situ tests carried out at the Lautaret site to determine the avalanche action at different scales confirm the reliability of this original approach. Its intrinsic characteristics make it especially suitable for application to different structures to provide new knowledge in this complex field.
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Liu, J., Y. Yu, Y. Wang, D. Han, and Y. Li. "Simulation of MRPC performance under different counting rates." Journal of Instrumentation 16, no. 11 (November 1, 2021): P11010. http://dx.doi.org/10.1088/1748-0221/16/11/p11010.
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Abstract The increasing luminosity of accelerators requires a higher counting rate capability of detectors. Previous studies have mostly simulated the detection efficiency of RPCs at a high counting rate but rarely involved the time resolution. In this paper, Geant4 software is used to simulate the interaction between particles and detectors, avalanche multiplication (considering the effect of space charge), and the generation, amplification, and shaping of the induction signal. A model is used to describe the establishment and recovery of the internal electric field in an MRPC at a high rate. We obtain the detection efficiency and time resolution of MRPCs with different structures at different counting rates. The simulation results are in good agreement with the experimental results, which verifies the feasibility of the model. At the same time, it has been confirmed that MRPCs built with the low resistivity glass developed by Tsinghua University can achieve a time resolution of 60–80 ps and a 90% efficiency at a flux up to 70 kHz/cm2 both in the experimental and simulation results.
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Ferry, Nicholas, Daniel Sturmer, Dylan Ward, Wanda Taylor, and Carlton Brett. "Origin and emplacement of the Blue Diamond landslide breccia, southern Nevada, U.S.A." Journal of Sedimentary Research 92, no. 8 (August 15, 2022): 659–75. http://dx.doi.org/10.2110/jsr.2021.021.
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ABSTRACT Landslide deposits are common in basin fill of tectonically active areas, including the Basin and Range province of western North America. However, interpreting and reconstructing ancient landsliding events from these deposits is challenging, but can be aided by detailed field analysis. Remnants of the Blue Diamond landslide breccia are exposed capping hills and ridges in the foothills of the eastern Spring Mountains near Blue Diamond, Nevada, USA. Uncertainties surrounding the origin and emplacement of the ancestral Blue Diamond landslide have emerged based on the disparate distribution of landslide outcrops. Therefore, in this study we used detailed sedimentological data and observations to interpret a two-phase emplacement history for the Blue Diamond landslide. Sedimentological observations are consistent with Blue Diamond landslide breccia emplacement as a rock avalanche. The presence of clastic dikes and flame structures and negligible incorporation of bedrock substrate material suggest that runout occurred over a saturated substrate. Flow transformation into a debris avalanche is ruled out because clast-count data show that debris entrainment was not sufficient to act as the sole mechanism behind the excessive mobility experienced by the Blue Diamond landslide. Instead, we propose that the excessive mobility was driven by flow entrainment of large Aztec Sandstone boulders and interaction with a saturated runout path substrate that caused a reduced basal frictional resistance, enabling initial emplacement onto Blue Diamond Hill. We therefore suggest that the Blue Diamond landslide was derived from a source area about 8.5 km northwest of the Blue Diamond townsite and flowed into the Blue Diamond Hill site where it was emplaced onto Moenkopi Formation atop the hill during the Miocene. Due to loading by this new overburden, incompetent gypsum horizons failed in the upper Kaibab Formation stratigraphically below the Moenkopi Formation. These failed gypsum horizons then served as a compound landslide rupture surface, transporting the overlying Moenkopi Formation and landslide breccia. This secondary emplacement likely ceased by late Miocene to Pliocene time.
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Akymenko, Olena. "СИНЕРГЕТИЧНІ ДЕТЕРМІНАНТИ РОЗВИТКУ ПРОМИСЛОВОГО ВИРОБНИЦТВА В УМОВАХ ОБРАННЯ УКРАЇНОЮ КУРСУ НА ЄВРОІНТЕГРАЦІЮ." PROBLEMS AND PROSPECTS OF ECONOMIC AND MANAGEMENT, no. 4(20) (2019): 157–69. http://dx.doi.org/10.25140/2411-5215-2019-4(20)-157-169.
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The article discusses the synergistic determinants of industrial production development with a view to recognizing synergetics as the newest positivist approach to the study of any open system with inherent elements of self-organization and cybernetic control, which will be modernized and modernized according to the general principles of synergistic worldview. The expediency of studying the set of determinants of industrial production development as a system revealing the integrity of the object, the unity and interdependence of the components characterized by different types of bonds to achieve a common result of the interaction of elements than the effectiveness of each of them individually, which characterizes the effect of synergy. It is proved that the need for national industrial revival actualizes the process of evaluating the development of industrial production, its determinants, since there is a systemic imbalance, the synergistic action of which impedes development. The most significant of these are: the state's remoteness from managing industrial development; low technological level of production and competitiveness; unsatisfactory export structure and level of support; critical deterioration of fixed assets; separation of banking and financial capital from industry; an avalanche outflow of frames; lack of a full-fledged innovation system; imperfection and incompleteness of legal support. It is proved that it is through the implementation of the State Strategy that the domestic industry will be transformed into a modern competitive complex, which would correspond to the level of a large European state.
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Xiao, Xuan, Pu Wang, and Kuo-Chen Chou. "Predicting the quaternary structure attribute of a protein by hybridizing functional domain composition and pseudo amino acid composition." Journal of Applied Crystallography 42, no. 2 (February 14, 2009): 169–73. http://dx.doi.org/10.1107/s0021889809002751.
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In vivo, some proteins exist as monomers (single polypeptide chains) and others as oligomers. The latter are composed of two or more chains (subunits) that are associated with each other through noncovalent interactions and, occasionally, disulfide bonds. Oligomers can be further classified into homo-oligomers (formed by identical subunits) and hetero-oligomers (formed by different subunits), and they form the structural basis of various biological functions such as cooperative effects, the allosteric mechanism and ion-channel gating. Therefore, it would be of less interest or of low priority for crystallographic scientists to crystallize a single protein chain and determine its three-dimensional structure if it is already known as part of an oligomer. However, it is both time-consuming and laborious to acquire such information on the quaternary structure attribute purely by experiment. In particular, with the avalanche of protein sequences generated in the post-genomic age, it is highly desirable to develop an automated method by which crystallographic scientists can rapidly and effectively identify which quaternary attribute a particular protein chain has according to its sequence information. In view of this, a computational method has been developed by hybridizing the approaches of functional domain composition and pseudo amino acid composition. For the convenience of crystallographic scientists, a user-friendly web server,PQSA-Pred, has been established at http://218.65.61.89:8080/bioinfo/pqsa-pred, by which the desired information can be easily obtained.
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Chebbi, Hela, Mohamed Sellami, and Sana Saidi. "Les déterminants et les conséquences de l’orientation entrepreneuriale : enseignements et voies futures de recherche basés sur une étude bibliométrique (2001-2016)." Revue internationale P.M.E. 31, no. 1 (April 10, 2018): 59–92. http://dx.doi.org/10.7202/1044689ar.
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RésuméLe concept de l’orientation entrepreneuriale (OE) apparaît dans la littérature comme un construit scientifique rigoureux et solide à partir duquel a pu s’élaborer un corps de connaissances cumulées et stables (Rauch, Wiklund, Lumpkin et Frese, 2009). Depuis le début duxxie siècle, nous avons assisté à un développement exponentiel des publications sur le thème de l’OE. Une avalanche de travaux de recherche publiés dans des revues académiques et professionnelles a émergé dans divers contextes pour accompagner cet intérêt grandissant à ce sujet. Il convient donc de comprendre et structurer la littérature sur l’OE afin d’en tirer les principaux enseignements. C’est dans ce cadre que nous conduisons cette étude bibliométrique qui présente en revue et structure les recherches publiées sur l’OE entre 2001 et 2016. Elle vise à identifier les principales voies futures de recherches sur le sujet. Cet article met particulièrement l’accent sur les facteurs susceptibles de favoriser ou freiner l’OE ainsi que sur les principales conséquences de ce concept. Il apporte une réponse à la question suivante : quels sont les interactions/liens, entre les déterminants et les conséquences de l’OE, encore inexplorés dans la littérature ? Pour ce faire, 492 articles académiques publiés sont examinés moyennant deux méthodologies différentes. La première, quantitative basée sur des indicateurs univariés, permet de dresser le paysage des travaux sur le sujet (revues, méthodologies les plus utilisées, pays). La deuxième, qualitative basée sur une analyse thématique (logiciel Freeplane) permet d’identifier tous les déterminants et les conséquences de l’OE tels qu’étudiés dans les travaux conceptuels, qualitatifs et quantitatifs. Des enseignements ont été tirés autour des interactions entre les différents facteurs.
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Podolskiy, E. A., G. Chambon, M. Naaim, and J. Gaume. "A review of finite-element modelling in snow mechanics." Journal of Glaciology 59, no. 218 (2013): 1189–201. http://dx.doi.org/10.3189/2013jog13j121.
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The finite-element method (FEM) is one of the main numerical analysis methods in continuum mechanics and mechanics of solids (Huebner and others, 2001). Through mesh discretization of a given continuous domain into a finite number of sub-domains, or elements, the method finds approximate solutions to sets of simultaneous partial differential equations, which express the behavior of the elements and the entire system. For decades this methodology has played an accelerated role in mechanical engineering, structural analysis and, in particular, snow mechanics. To the best of our knowledge, the application of finite-element analysis in snow mechanics has never been summarized. Therefore, in this correspondence we provide a table with a detailed review of the main FEM studies on snow mechanics performed from 1971 to 2012 (40 papers), for facilitating comparison between different mechanical approaches, outlining numerical recipes and for future reference. We believe that this kind of compact review in a tabulated form will produce a snapshot of the state of the art, and thus become an appropriate, timely and beneficial reference for any relevant follow-up research, including, for example, not only snow avalanche questions, but also modeling of snow microstructure and tire–snow interaction. To that end, this correspondence is organized according to the following structure. Table 1 includes all essential information about previously published FEM studies originally developed to investigate stresses in snow with all corresponding mechanical and numerical parameters. Columns in Table 1 provide references to particular studies, placed in chronological order. Rows correspond to the main model parameters and other details of each considered case.
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Schirmer, M., and B. Jamieson. "Limitations of using a thermal imager for snow pit temperatures." Cryosphere Discussions 7, no. 5 (October 29, 2013): 5231–53. http://dx.doi.org/10.5194/tcd-7-5231-2013.
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Abstract. Driven by temperature gradients, kinetic snow metamorphism is important for avalanche formation. Even when gradients appear to be insufficient for kinetic metamorphism, based on temperatures measured 10 cm apart, faceting close to a~crust can still be observed. Recent studies that visualized small scale (< 10 cm) thermal structures in a profile of snow layers with an infrared (IR) camera produced interesting results. The studies found melt-freeze crusts to be warmer or cooler than the surrounding snow depending on the large scale gradient direction. However, an important assumption within the studies was that a thermal photo of a freshly exposed snow pit was similar enough to the internal temperature of the snow. In this study, we tested this assumption by recording thermal videos during the exposure of the snow pit wall. In the first minute, the results showed increasing gradients with time, both at melt-freeze crusts and at artificial surface structures such as shovel scours. Cutting through a crust with a cutting blade or a shovel produced small concavities (holes) even when the objective was to cut a planar surface. Our findings suggest there is a surface structure dependency of the thermal image, which is only observed at times with large temperature differences between air and snow. We were able to reproduce the hot-crust/cold-crust phenomenon and relate it entirely to surface structure in a temperature-controlled cold laboratory. Concave areas cooled or warmed slower compared with convex areas (bumps) when applying temperature differences between snow and air. This can be explained by increased radiative transfer or convection by air at convex areas. Thermal videos suggest that such processes influence the snow temperature within seconds. Our findings show the limitations of the use of a thermal camera for measuring pit-wall temperatures, particularly in scenarios where large gradients exist between air and snow and the interaction of snow pit and atmospheric temperatures are enhanced. At crusts or other heterogeneities, we were unable to create a sufficiently homogenous snow pit surface and non-internal gradients appeared at the exposed surface. The immediate adjustment of snow pit temperature as it reacts with the atmosphere complicates the capture of the internal thermal structure of a snowpack even with thermal videos. Instead, the shown structural dependency of the IR signal may be used to detect structural changes of snow caused by kinetic metamorphism. The IR signal can also be used to measure near surface temperatures in a homogenous new snow layer.
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Streltsov, Victor A., Nobuo Ishizawa, and Shunji Kishimoto. "Synchrotron X-ray Imaging of the Electron Density in RFeO3 (R = Y, Ho) Using an APD Detector." Journal of Synchrotron Radiation 5, no. 5 (September 1, 1998): 1309–16. http://dx.doi.org/10.1107/s0909049598001447.
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Structure factors for small hydrothermally grown yttrium and holmium orthoferrites, RFeO3 (R = Y, Ho), were measured with focused synchrotron radiation at wavelengths of 0.70 and 0.84 Å using both scintillation and high-speed avalanche photodiode (APD) detectors. Resulting APD Δρ images showed striking correlations between aspherical electron densities around Fe and rare-earth metals. Approximate high symmetry in the Δρ images indicates that cations deform the electron density far more strongly than the O atoms. The Ho—Fe magnetic interactions appear to affect the electron density distribution of the Fe atoms and the magnetic phase transitions. Space group Pnma, orthorhombic, YFeO3 (APD): M r = 192.76, a = 5.5931 (3), b = 7.6102 (4), c = 5.2806 (3) Å, V = 224.77 (2) Å3, Z = 4, D x = 5.695 Mg m−3, μ0.84 = 15.56 mm−1, F(000) = 356, T = 293 K, R = 0.045, wR = 0.073, S = 4.83 (9) for 1282 unique reflections; HoFeO3 (APD): M r = 268.78, a = 5.5922 (3), b = 7.6157 (5), c = 5.2798 (3) Å, V = 224.86 (2) Å3, Z = 4, D x = 7.939 Mg m−3, μ0.84 = 61.98 mm−1, F(000) = 356, T = 293 K, R = 0.036, wR = 0.037, S = 3.07 (6) for 1284 unique reflections.
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Medintsev, Vladislav A. "Methodology for implementing the personal approach in adaptive learning systems." Yaroslavl Pedagogical Bulletin 1, no. 118 (2021): 151–61. http://dx.doi.org/10.20323/1813-145x-2021-1-118-151-161.
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The accelerated introduction of digital technologies in education has already acquired an avalanche-like mode, which has become an effective factor in research to improve the conceptual and technological solutions for the development and application of various synthetic learning environments. One of the most important areas of their improvement is giving them flexibility to maximize the capabilities of each student. In the theory and practice of psychology, this route is associated with various options for implementing the personal approach as a personalization of learning. Engineering and communication technologies in education open up opportunities for personalizing learning, which have expanded significantly, but the problems of theory and practice of education have also become more relevant. Various options for personalization of training are also implemented when creating synthetic artificial environments, one of the actively developed varieties of which are adaptive learning systems (ALS). The main factors that complicate the use of ALS, experts attribute their high cost and insufficient efficiency, which necessitates the search for new approaches to the development of ALS on the most clear, rational theoretical and methodological principles. Also, the reason for the limited use of ALS is that the personalization inherent in their design does not allow for the necessary consideration the shades of students’ socio-psychological specifics in combination with regulatory requirements, which teachers achieve by developing and implementing their training programs.Conceptually, research on ALS is an example of the interacting the natural science and humanitarian paradigms in human studies. To increase the effectiveness of such interaction, logically relevant theoretical models are needed that are applicable to a wide range of subjects studied within the framework of the humanitarian paradigm. Such a theoretical model for the description and development of ALS, in particular, can be built on the basis of the set-theoretic method for process description. The article deals with the application of this method to the structure and functioning of the ALS and the implementation of the adaptation principle in it.
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Rezig, El Kindi, Anshul Bhandari, Anna Fariha, Benjamin Price, Allan Vanterpool, Vijay Gadepally, and Michael Stonebraker. "DICE." Proceedings of the VLDB Endowment 14, no. 12 (July 2021): 2819–22. http://dx.doi.org/10.14778/3476311.3476353.
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In order to conduct analytical tasks, data scientists often need to find relevant data from an avalanche of sources (e.g., data lakes, large organizational databases). This effort is typically made in an ad hoc, non-systematic manner, which makes it a daunting endeavour. Current data discovery systems typically require the users to find relevant tables manually, usually by issuing multiple queries (e.g., using SQL). However, expressing such queries is nontrivial, as it requires knowledge of the underlying structure (schema) of the data organization in advance. This issue is further exacerbated when data resides in data lakes, where there is no predefined schema that data must conform to. On the other hand, data scientists can often come up with a few example records of interest quickly. Motivated by this observation, we developed DICE---a human-in-the-loop system for <u>D</u>ata d<u>I</u>s<u>C</u>overy by <u>E</u>xample---that takes user-provided example records as input and returns more records that satisfy the user intent. DICE's key idea is to synthesize a SQL query that captures the user intent, specified via examples. To this end, DICE follows a three-step process: (1) DICE first discovers a few candidate queries by finding join paths across tables within the data lake. (2) Then DICE consults with the user for validation by presenting a few records to them, and, thus, eliminating spurious queries. (3) Based on the user feedback, DICE refines the search and repeats the process until the user is satisfied with the results. We will demonstrate how DICE can help in data discovery through an interactive, example-based interaction.
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Minotti, Alessandro. "Characterization of the DUNE photodetectors and study of the event burst phenomenon." Journal of Physics: Conference Series 2156, no. 1 (December 1, 2021): 012242. http://dx.doi.org/10.1088/1742-6596/2156/1/012242.
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Abstract The Deep Underground Neutrino Experiment (DUNE) is an upcoming neutrino physics experiment that will answer some of the most compelling questions in particle physics and cosmology. The DUNE far detectors employ silicon photomultipliers (SiPMs) to detect light produced by charged particles interacting in a large liquid argon time projection chamber (LArTPC). The SiPMs are photosensors consisting of an array of single-photon avalanche diodes (SPAD) operating in Geiger mode. Their high sensitivity and dynamic range, as well as the possibility to fill large surfaces with high-granularity sensors, makes them an ideal choice for DUNE. An international consortium of research groups is currently engaged in a systematic comparison of the performances of the SiPM models that have been custom developed for DUNE by two manufacturers. Such detailed studies, which include gain measurements and a structure study of the dark count rate at 77 K, are meant to determine the best choice of the photodetection system for DUNE, as well as characterize the response of the chosen detectors for the DUNE simulation. Moreover, an investigation of a newly observed phenomenon, in which quick bursts of tens of events at close range are collected in individual SiPMs, is being carried out, which potentially impacts the design of future models and their implementation in particle physics experiments.
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Rodicheva, Irina V. "Dynamics of demand in the labor market in the southern regions of Russia during the COVID-19 pandemic." Siberian Socium 4, no. 3 (2020): 49–58. http://dx.doi.org/10.21684/2587-8484-2020-4-3-49-58.
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The events taking place in 2020 in the world in general and in Russia in particular have dramatically shaken up all spheres of public life. The quarantine measures have significantly blocked the channels of business interaction and enabled a pause mode in a wide range of economic processes. The state of the labor market during the crisis period is a defining indicator that demonstrates the strategies of employers and employees. This article studies the dynamics of a key indicator of the labor market — the demand for labor in the southern regions of Russia. The author aims to analyze the dynamics of labor market demand in a number of cities in southern regions of Russia in the key periods of spring 2020 events associated with the COVID-19 pandemic. The analysis covers six cities of southern Russia, located in different regions and significantly different specific structure of the economic sphere. The indicators of the southern regions as a whole were considered separately, which allowed to diagnose their condition and draw conclusions about ther particular “painful” dependencies. The labor market of the southern Russian cities is characterized by stable seasonality structures and highly specialized orientation in a number of territories. These private characteristics have a direct impact on complex economic indicators. The eployment of quarantine measures on the eve of the holiday season and preventive saturation with epidemiological security measures of the tourist business in the country threatened to turn into an economic disaster for a number of territories. The novelty of this topic lies in the fact that the forced lockdown had an external character and it highlighted a significant dependence of economic actions of business on the decisions of the authorities. The new conditions of destabilization were a test of stability of organizational links of different spheres of public life. An essential factor that destabilized the behavior of key labor market participants was the mass media, which spread false or unverified information. The author draws a conclusion about the characteristic avalanche-like declines and rises in demand in the labor market of the southern regions and about the uneven distribution of reactions in different cities with similar geographical locations.
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Frei, Esther R., Ignacio Barbeito, Lisa M. Erdle, Elisabeth Leibold, and Peter Bebi. "Evidence for 40 Years of Treeline Shift in a Central Alpine Valley." Forests 14, no. 2 (February 17, 2023): 412. http://dx.doi.org/10.3390/f14020412.
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Alpine treeline ecosystems are generally expected to advance with increasing temperatures and after land-use abandonment. Multiple interacting factors modify this trend. Understanding the long-term processes underlying treeline advance is essential to predict future changes in structure and function of mountain ecosystems. In a valley in the Central Swiss Alps, we re-assessed a 40-year-old survey of all treeline trees (>0.5 m height) and disentangled climate, topographical, biotic, and disturbance (land use and avalanche risk) factors that have led to treeline advance with a combination of ground-based mapping, decision tree, and dendroecological analyses. Between the first ground survey in 1972/73 and the resurvey in 2012, treeline advanced on average by 10 meters per decade with a maximum local advance of 42 meters per decade. Larch consistently advanced more on south-facing slopes, while pine advance was greater on north-facing slopes. Newly established spruce mostly represented infilling below the previous treeline. The forefront of treeline advance above 2330 m a.s.l. occurred mainly on favorable microsites without competing dwarf shrub vegetation. At slightly lower elevations, treeline advanced mainly on sites that were used for agriculture at the beginning of the 20th century. This study indicates that although treeline advances under the effect of climate warming, a combination of additional ecological factors controls this advance at regional and local scales.
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Huggel, Christian, Jorge Luis Ceballos, Bernardo Pulgarĺn, Jair Ramírez, and Jean-Claude Thouret. "Review and reassessment of hazards owing to volcano–glacier interactions in Colombia." Annals of Glaciology 45 (2007): 128–36. http://dx.doi.org/10.3189/172756407782282408.
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AbstractThe Cordillera Central in Colombia hosts four important glacier-clad volcanoes, namely Nevado del Ruiz, Nevado de Santa Isabel, Nevado del Tolima and Nevado del Huila. Public and scientific attention has been focused on volcano–glacier hazards in Colombia and worldwide by the 1985 Nevado del Ruiz/Armero catastrophe, the world’s largest volcano–glacier disaster. Important volcanological and glaciological studies were undertaken after 1985. However, recent decades have brought strong changes in ice mass extent, volume and structure as a result of atmospheric warming. Population has grown and with it the sizes of numerous communities located around the volcanoes. This study reviews and reassesses the current conditions of and changes in the glaciers, the interaction processes between ice and volcanic activity and the resulting hazards. Results show a considerable hazard potential from Nevados del Ruiz, Tolima and Huila. Explosive activity within environments of snow and ice as well as non-eruption-related mass movements induced by unstable slopes, or steep and fractured glaciers, can produce avalanches that are likely to be transformed into highly mobile debris flows. Such events can have severe consequences for the downstream communities. Integrated monitoring strategies are therefore essential for early detection of emerging activity that may result in hazardous volcano–ice interaction. Corresponding efforts are currently being strengthened within the framework of international programmes.
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Wu, Hao, Zhaoyu Chen, Zhijiang Wang, Bo Rao, Wei Jiang, and Ya Zhang. "On the breakdown process of capacitively coupled plasma in carbon tetrafluoride." Journal of Physics D: Applied Physics 55, no. 25 (March 30, 2022): 255203. http://dx.doi.org/10.1088/1361-6463/ac5772.
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Abstract Capacitively coupled plasma (CCP) in CF4 has been widely used in the semiconductor industry. However, its breakdown process at low pressure has rarely been studied. In this paper, we study the whole CCP breakdown process in CF4 using the 1D implicit particle-in-cell/Monte Carlo collision (PIC/MCC) method. The detailed evolution of the plasma parameters is given, and both the particle balance and power evolution are discussed. The electron density initially grows exponentially, driven by the penetrating electric field. Both the ionization in the discharge gap and the boundary interaction are significant for electron avalanches. The formation of a sheath maximizes the ionization rate and the heating power, which thoroughly changes the field structure. In the post-breakdown phase, the growing negative ion density shrink the sheaths and changes the heating mode from the α mode to the drift-ambipolar mode. The particle generation rate and heating power show a growth trend after a brief decline. The growth of the recombination rate slowly balances the gain and loss of ions, which finally stabilizes the discharge.
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Nishimura, K., H. Narita, N. Maeno, and K. Kawada. "The Internal Structure of Powder-Snow Avalanches." Annals of Glaciology 13 (1989): 207–10. http://dx.doi.org/10.3189/s0260305500007904.
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The internal structure of powder-snow avalanches was investigated at Kurobe Canyon in the Shiai-dani area of Japan in 1988. Internal velocity was derived for avalanches of this kind by frequency analysis of impact-force data, and was found to undergo a remarkable change with time. The shear of the avalanche flow was estimated to range from 1 to 7 s−1. The front region of the avalanche wind was observed to precede the front of the avalanche by a distance of 17.3 m. The maximum wind velocity was comparable with the internal velocity of the front region of the avalanche.
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Nishimura, K., H. Narita, N. Maeno, and K. Kawada. "The Internal Structure of Powder-Snow Avalanches." Annals of Glaciology 13 (1989): 207–10. http://dx.doi.org/10.1017/s0260305500007904.
Full textAbstract:
The internal structure of powder-snow avalanches was investigated at Kurobe Canyon in the Shiai-dani area of Japan in 1988. Internal velocity was derived for avalanches of this kind by frequency analysis of impact-force data, and was found to undergo a remarkable change with time. The shear of the avalanche flow was estimated to range from 1 to 7 s−1. The front region of the avalanche wind was observed to precede the front of the avalanche by a distance of 17.3 m. The maximum wind velocity was comparable with the internal velocity of the front region of the avalanche.
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Thibert, E., and D. Baroudi. "Impact energy of an avalanche on a structure." Annals of Glaciology 51, no. 54 (2010): 45–54. http://dx.doi.org/10.3189/172756410791386634.
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AbstractThe impact energy of an avalanche on the flat surface of an instrumented structure has been quantified by full-scale experiments performed at the Lautaret avalanche test site, France. The deformation and acceleration of the structure were measured during the avalanche. The impact energy of the avalanche was calculated from an energy balance via the mechanical energy theorem. First the elastic potential energy and kinetic energy of the structure were calculated from the measured deformations and an adequate mechanical model of the structure. Internal energy dissipation due to material damping and potential plastic deformation was calculated. Finally the mechanical work done on the structure by the avalanche forces was deduced from the energy balance. Results show that the elastic energy is the main component of the energy injected in the structure. The kinetic and viscous components are negligible because of the very low displacement rate of the structure during the impact. Another important result is that the maximum of the mechanical power (work rate) is done when the head of the avalanche impacts the structure. This occurs before the pressure reaches its nominal value, approximately when the product of the pressure by the pressure rate is maximum.
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Staron, Lydie, Farhang Radjai, and Jean-Pierre Vilotte. "Granular micro-structure and avalanche precursors." Journal of Statistical Mechanics: Theory and Experiment 2006, no. 07 (July 31, 2006): P07014. http://dx.doi.org/10.1088/1742-5468/2006/07/p07014.
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Sovilla, B., I. Sonatore, Y. Bühler, and S. Margreth. "Wet-snow avalanche interaction with a deflecting dam: field observations and numerical simulations in a case study." Natural Hazards and Earth System Sciences 12, no. 5 (May 11, 2012): 1407–23. http://dx.doi.org/10.5194/nhess-12-1407-2012.
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Abstract. In avalanche-prone areas, deflecting dams are widely used to divert avalanches away from endangered objects. In recent years, their effectiveness has been questioned when several large and multiple avalanches have overrun such dams. In 2008, we were able to observe a large wet-snow avalanche, characterized by an high water content, that interacted with a deflecting dam and overflowed it at its lower end. To evaluate the dam's performance, we carried out an airborne laser scanning campaign immediately after the avalanche. This data, together with a video sequence made during the avalanche descent, provided a unique data set to study the dynamics of a wet dense snow avalanche and its flow behavior along a deflecting dam. To evaluate the effect of the complex flow field of the avalanche along the dam and to provide a basis for discussion of the residual risk, we performed numerical simulations using a two-dimensional dense snow avalanche dynamics model with entrainment. In comparison to dry dense snow avalanches, we found that wet-snow avalanches, with high water content, seem to be differently influenced by the local small-scale topography roughness. Rough terrain close to the dam deflected the flow to produce abrupt impacts with the dam. At the impact sites, instability waves were generated and increased the already large flow depths. The complex flow dynamics around the dam may produce large, local snow deposits. Furthermore, the high water content in the snow may decrease the avalanche internal friction angle, inducing wet-snow avalanches to spread further laterally than dry-snow avalanches. Based on our analysis, we made recommendations for designing deflecting dams and for residual risk analysis to take into account the effects of wet-snow avalanche flow.
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Tykhanovych, Ieuhen, and Volodymyr Bilanyuk. "Show avalanche slide conditions in Chornohora Massif (Ukrainian Carpathians)." Visnyk of the Lviv University. Series Geography, no. 50 (December 28, 2016): 359–68. http://dx.doi.org/10.30970/vgg.2016.50.8725.
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There are about eighty avalanche geocomplexes, which belong to different classes according to avalanche activity, in the mountain massif Chornohora. One of the main tasks is an investigation of natural conditions of avalanche formation because of snow mass slide process influence on the environment and human activities. Snow-avalanche formation conditions within landscape complexes of Chornohora mountain massif in Ukrainian Carpathians, depending on group of factors (landscape structure, meteorological quantity and phenomenon and other), are considered. Special attention is paid to study the morphological structure of snow and stratification structure of snow cover as the main avalanche slide factors. The landscape structure and relief of territory with avalanche activity are analyzed. All avalanche genetic types, which are identified in the Chornohora mountain massif, are located on the steep and very steep slope on old-glacial relief forms (slope steepness – 15–45° (Miller, 1966)). Avalanche activity within research territory limits of the Pozhyzhevska snow-avalanche station was analyzed and short characteristic of avalanche subperiod during research time was presented. The dynamics of snow depth and snow cower structure, temperature regime of air and snow during research period was investigated. The main indexes of meteorological phenomena, which are typical for the days when avalanche activity was identified, were determined. Analysis of meteorological quantity and phenomenon indexes is realized on the base of own research information and technical report of Pozhyzhevska snow-avalanche station. Based on the results of the investigation natural conditions of snow avalanche slide of all genetic types (polygenetic (inducted by snowfall and blizzard) and epigenetic (inducted by the melt of snow – insolation and advection process)) were determined. The typical profile of snow cover, which is characterized by avalanche sliding process, is proposed for every genetic type of avalanche. The characteristics of snow profiles are presented in figures. Key words: avalanche, Ukrainian Carpathians, snow cover, meteorological phenomena.
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Nishimura, K., N. Maeno, F. Sandersen, K. Kristensen, H. Norem, and K. Lied. "Observations of the dynamic structure of snow avalanches." Annals of Glaciology 18 (1993): 313–16. http://dx.doi.org/10.3189/s026030550001171x.
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During two winters, 1990–92, the dynamic structures of snow avalanches were studied in western Norway. Artificially released wet-snow avalanches ran down the avalanche chute and stopped in front of the retaining dam. Running velocity distributions were obtained not only by video tape recorder, but also by various other recording instruments. Internal velocity was derived for the last avalanche by frequency analysis of impact pressure and optical sensor data. The vertical velocity shear of the avalanche flow has been estimated to be in the range 1–10 s−1.
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Nishimura, K., N. Maeno, F. Sandersen, K. Kristensen, H. Norem, and K. Lied. "Observations of the dynamic structure of snow avalanches." Annals of Glaciology 18 (1993): 313–16. http://dx.doi.org/10.1017/s026030550001171x.
Full textAbstract:
During two winters, 1990–92, the dynamic structures of snow avalanches were studied in western Norway. Artificially released wet-snow avalanches ran down the avalanche chute and stopped in front of the retaining dam. Running velocity distributions were obtained not only by video tape recorder, but also by various other recording instruments. Internal velocity was derived for the last avalanche by frequency analysis of impact pressure and optical sensor data. The vertical velocity shear of the avalanche flow has been estimated to be in the range 1–10 s−1.