scholarly journals The Heat of the Flow: Thermal Equilibrium in Gravitational Mass Flows

2018 ◽  
Vol 45 (20) ◽  
Author(s):  
Jan‐Thomas Fischer ◽  
Roland Kaitna ◽  
Kilian Heil ◽  
Ingrid Reiweger
Keyword(s):  
Thermal Equilibrium ◽  
Gravitational Mass ◽  
Mass Flows

scholarly journals Stress anisotropy in natural debris flows during impacting a monitoring structure

Landslides ◽  
2021 ◽  
Author(s):  
Georg Nagl ◽  
Johannes Hübl ◽  
Roland Kaitna
Keyword(s):  
Debris Flows ◽  
Flow Direction ◽  
Vertical Wall ◽  
Force Plate ◽  
Frictional Resistance ◽  
Gravitational Mass ◽  
Analytical Models ◽  
Stress Anisotropy ◽  
Mass Flows ◽  
Stress Ratios

AbstractThe frictional resistance of rock and debris is supposed to induce stress anisotropy in the unsteady, non-uniform flow of gravitational mass flows, including debris flows. Though widely used in analytical models and numerical simulation tools, concurrent measurements of stresses in different directions are not yet available for natural flow events. The present study aims to investigate the relation of longitudinal and bed-normal stress exerted by two natural debris flows impacting a monitoring barrier in the Gadria creek, Italy. For that, a force plate in front of a barrier was used to continuously record forces normal to the channel bed, whereas load cells mounted on the vertical wall of the barrier recorded forces in flow direction. We observed an anisotropic stress state during most of the flow events, with stress ratios ranging between 0.1 and 3.5. Video recordings reveal complex deposition and re-mobilization patterns in front of the barrier during surges and highlight the unsteady nature of debris flows. These first-time in-situ measurements confirm the assumption of stress anisotropy in natural debris flows for gravitational mass flows, and provide data for model testing.

scholarly journals Mortality profiles of Castor and Trogontherium (Mammalia: Rodentia, Castoridae), with notes on the site formation of the Mid-Pleistocene hominin locality Bilzingsleben II (Thuringia, Central Germany)

2020 ◽  
Vol 76 (1) ◽  
pp. 40-58
Author(s):  
Wolf-Dieter Heinrich ◽  
Lutz C. Maul
Keyword(s):  
Homo Erectus ◽  
Gravitational Mass ◽  
Site Formation ◽  
Middle Pleistocene ◽  
Older Individuals ◽  
Archaeological Remains ◽  
Human Occupation ◽  
Mortality Pattern ◽  
Mass Flows ◽  
The Difference

The Middle Pleistocene site Bilzingsleben II is well-known for its wealth of vertebrate and archaeological remains. Of particular importance is the record of Homo erectus bilzingslebenensis. Most palaeontologists consider the find horizon as a primary vertebrate deposit formed during human occupation, while some archaeologists attribute its formation to turbulent gravitational mass flows, inundation or a combination of both. Here we present mortality profiles of the beavers Castor and Trogontherium to provide further arguments to this controversial discussion. The mortality profiles of Castor from Bilzingsleben II, Weimar-Ehringsdorf and Weimar-Taubach are largely identical indicating similar taphonomic filters that were effective in the formation of the find layers. Individuals, which were tentatively classified as suspected ±2–2½ year old beavers dominate by far in all three sites. The structure of these mortality profiles shows similarities to Stiner’s (1990) “prime dominated mortality pattern”, which is indicative of human hunting. This consideration is supported by the difference of the mortality profile of Trogontherium from Bilzingsleben II (dominance of older individuals) in relation to the profiles of non-hominin generated assemblages of Tegelen and Mosbach 2 (dominance of younger individuals). Thus, our data support the interpretation of the Palaeolithic find horizon of Bilzingsleben II as a primary vertebrate deposit, but not the gravitational mass flow and inundation hypotheses.

In-situ measurements of stress anisotropy in natural debris flows 

2021 ◽  
Author(s):  
Georg Nagl ◽  
Johannes Hübl ◽  
Roland Kaitna
Keyword(s):  
Debris Flows ◽  
Stress Ratio ◽  
Vertical Wall ◽  
Fluid Pressure ◽  
Pore Fluid ◽  
Gravitational Mass ◽  
Analytical Models ◽  
Pore Fluid Pressure ◽  
Stress Anisotropy ◽  
Mass Flows

<p>Stress anisotropy affects the motion of gravitational mass flows, including debris flows, rock and snow avalanches. Though widely used in analytical models and numerical simulation tools, direct measurements of stress anisotropy in debris flows are not yet available. The present study aims to investigate the ratio of longitudinal to normal pressure exerted by two natural debris flows impacting a monitoring structure in the Gadria creek, IT. The fin-shaped structure in the middle of the channel is equipped with a force plate upstream of the barrier and load cells on the vertical wall of the barrier, continuously recording forces in flow and bed-normal direction. Additionally, the flow height and basal pore fluid pressure were measured. Here we present data from surges of two debris-flow events with peak flow heights of 2.5 m and velocities up to 4 m/s. The ratio of pore fluid pressure to normal stress (often termed liquefaction ratio) reached values up to 0.8. We find an anisotropic stress state during most of the flow event, with stress ratios ranging between 0.1 and 3.5. Video recordings reveal complex deposition and re-mobilization patterns in front of the barrier during surges and highlight the unsteady nature of debris flows. We find a correlation of the stress ratio with flow depth. There is a weak correlation between stress ratio and liquefaction ratio during the falling limb of the surge hydrographs.  Our monitoring data confirm the assumption of stress anisotropy in natural debris flows and support the earth-pressure concept used for gravitational mass flows.</p>

Structured methods for improving flow measurement accuracy in pipelines

2020 ◽  
pp. 30-35
Author(s):  
Gurami N. Akhobadze
Keyword(s):  
Flow Measurement ◽  
Measurement Accuracy ◽  
Directional Coupler ◽  
Signal To Noise Ratio ◽  
Scattered Wave ◽  
Orthogonal Polarization ◽  
Flow Sensors ◽  
Information Signal ◽  
Mass Flows ◽  
Processing Device

In the age of digital transformation of production processes in industry and science the development and design of intelligent flow sensors for granular and liquid substances transferring through pipelines becomes more important. With this in view new approaches for improving the accuracy of microwave flowmeters are proposed. Taking into account the characteristics ofelectromagnetic waves propagating through a pipeline, a wave scattered by inhomogeneities of the controlled medium is analyzed. Features of the transformation of the polarized scattered wave limiting the geometric dimensions of the pipeline and optimizing the values of the useful scattered signal are revealed. Expediency of collection of the information signal with orthogonal polarization of the scattered wave and through a directional coupler is substantiated. The method of estimating the measurement accuracy with reference to the signal-to-noise ratio at the input of the processing device is given. The research results can be used in cryogenic machine engineering to measure volume and mass flows of liquid cryogenic products.

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