Experimental analysis of snow micropenetrometer (SMP) cone penetration in homogeneous snow layers

2013 ◽  
Vol 50 (10) ◽  
pp. 1044-1054 ◽  
Author(s):  
Alec van Herwijnen
Keyword(s):  
Penetration Depth ◽  
Experimental Studies ◽  
Small Diameter ◽  
High Porosity ◽  
Snow Density ◽  
Cone Penetration ◽  
Avalanche Forecasting ◽  
Snow Stratigraphy ◽  
Image Velocimetry ◽  
Compaction Zone

The cone penetration test (CPT) is widely used to determine in situ soil and snow characteristics and stratigraphy. For avalanche forecasting, knowledge about snow stratigraphy is of crucial importance. Portable electric cone penetrometers have therefore been developed with the goal of obtaining rapid and accurate measurements of snow stratigraphy. The most widely used electric penetrometer is the snow micropenetrometer (SMP), a constant-speed small-diameter cone penetrometer. The SMP was specifically designed to study snow and is not a penetrometer in the geotechnical sense, as the diameter of the SMP cone (5 mm) is comparable to the typical size of snow grains (0.1 to 1 mm). Previous numerical and experimental studies of the CPT in granular materials have highlighted the importance of material compaction around the cone. Nevertheless, given the high porosity of snow, compaction of failed elements around the SMP cone is generally neglected when interpreting SMP force signals. To verify this assumption, microcomputed tomography and particle image velocimetry were used to investigate the deformation of snow during SMP cone penetration. Results from laboratory experiments with uniform snow show that a compaction zone around the SMP tip develops during penetration. The size of the compaction zone was on average twice as large as the actual size of the cone, increasing with increasing snow density. Furthermore, an average penetration depth of about 40 mm was required for the compaction zone to develop fully. This critical penetration depth roughly decreased with increasing snow density. These results show that the compaction zone around the SMP tip is far from negligible and has to be accounted for when interpreting SMP force measurements.

Technical Study of Laminated Template Electroforming in Fabrication of Metal Parts

2014 ◽  
Vol 621 ◽  
pp. 121-126
Author(s):  
Hui Fan ◽  
Yang Pei Zhao
Keyword(s):  
Experimental Studies ◽  
Small Diameter ◽  
Dimensional Accuracy ◽  
Spray Distance ◽  
Metal Parts ◽  
Precise Locality ◽  
Filling Method ◽  
Specific Shape ◽  
Technical Study ◽  
Equipment Configuration

Laminated templates electroforming (LTE) is one kind of metal-parts directly forming technologies which are based on discrete/accumulation theory. This paper introduces the forming principle, equipment configuration and experimental studies. By using templates as auxiliary tool and jet electroforming as filling method, the current density of electroforming was significantly improved and a group of copper parts in specific shape were fabricated. Experimental results show that on-load voltage, nozzle diameter, spray distance, spray flow velocity have direct influence on processing speed and locality. A small diameter of nozzle and short spray distance helps to achieve a precise locality and good dimensional accuracy, after process parameters have been optimized.

scholarly journals Comparison of Selected Terramechanical Test Procedures and Cartographic Indices to Predict Rutting Caused by Machine Traffic during a Cut-to-Length Thinning Operation

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 113
Author(s):  
Marian Schönauer ◽  
Stephan Hoffmann ◽  
Joachim Maack ◽  
Martin Jansen ◽  
Dirk Jaeger
Keyword(s):  
Shear Strength ◽  
Penetration Depth ◽  
Sustainable Forest Management ◽  
Operating Conditions ◽  
Soil Conditions ◽  
Cone Penetration ◽  
Topographic Wetness Index ◽  
Mixed Stands ◽  
Thinning Operation ◽  
Cone Index

Timber harvesting operations using heavy forest machinery frequently results in severe soil compaction and displacement, threatening sustainable forest management. An accurate prediction of trafficability, considering actual operating conditions, minimizes these impacts and can be facilitated by various predictive tools. Within this study, we validated the accuracy of four terramechanical parameters, including Cone Index (MPa, Penetrologger), penetration depth (cm, Penetrologger), cone penetration (cm blow−1, dual-mass dynamic cone penetrometer) and shear strength (kPa, vane meter), and additionally two cartographic indices (topographic wetness index and depth-to-water). Measurements applying the four terramechanical approaches were performed at 47 transects along newly assigned machine operating trails in two broadleaved dominated mixed stands. After the CTL thinning operation was completed, measurement results and cartographic indices were correlated against rut depth. Under the rather dry soil conditions (29 ± 9 vol%), total rut depth ranged between 2.2 and 11.6 cm, and was clearly predicted by rut depth after a single pass of the harvester, which was used for further validations. The results indicated the easy-to-measure penetration depth as the most accurate approach to predict rut depth, considering coefficients of correlation (rP = 0.44). Moreover, cone penetration (rP = 0.34) provided reliable results. Surprisingly, no response between rut depth and Cone Index was observed, although it is commonly used to assess trafficability. The relatively low moisture conditions probably inhibited a correlation between rutting and moisture content. Consistently, cartographic indices could not be used to predict rutting. Rut depth after the harvester pass was a reliable predictor for total rut depth after 2–5 passes (rP = 0.50). Rarely used parameters, such as cone penetration or shear strength, outcompeted the highly reputed Cone Index, emphasizing further investigations of applied tools.

scholarly journals Estimating snow water equivalent over long mountain transects using snowmobile-mounted ground-penetrating radar

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. WA183-WA193 ◽  
Author(s):  
W. Steven Holbrook ◽  
Scott N. Miller ◽  
Matthew A. Provart
Keyword(s):  
Ground Penetrating Radar ◽  
Snow Water Equivalent ◽  
Ground Surface ◽  
Snow Accumulation ◽  
Accurate Estimation ◽  
Snow Density ◽  
Snow Stratigraphy ◽  
Flood Estimation ◽  
Snow Water ◽  
Ground Penetrating

The water balance in alpine watersheds is dominated by snowmelt, which provides infiltration, recharges aquifers, controls peak runoff, and is responsible for most of the annual water flow downstream. Accurate estimation of snow water equivalent (SWE) is necessary for runoff and flood estimation, but acquiring enough measurements is challenging due to the variability of snow accumulation, ablation, and redistribution at a range of scales in mountainous terrain. We have developed a method for imaging snow stratigraphy and estimating SWE over large distances from a ground-penetrating radar (GPR) system mounted on a snowmobile. We mounted commercial GPR systems (500 and 800 MHz) to the front of the snowmobile to provide maximum mobility and ensure that measurements were taken on pristine snow. Images showed detailed snow stratigraphy down to the ground surface over snow depths up to at least 8 m, enabling the elucidation of snow accumulation and redistribution processes. We estimated snow density (and thus SWE, assuming no liquid water) by measuring radar velocity of the snowpack through migration focusing analysis. Results from the Medicine Bow Mountains of southeast Wyoming showed that estimates of snow density from GPR ([Formula: see text]) were in good agreement with those from coincident snow cores ([Formula: see text]). Using this method, snow thickness, snow density, and SWE can be measured over large areas solely from rapidly acquired common-offset GPR profiles, without the need for common-midpoint acquisition or snow cores.

scholarly journals Recording microscale variations in snowpack layering using near-infrared photography

2010 ◽  
Vol 56 (195) ◽  
pp. 75-80 ◽  
Author(s):  
Ken D. Tape ◽  
Nick Rutter ◽  
Hans-Peter Marshall ◽  
Richard Essery ◽  
Matthew Sturm
Keyword(s):  
Near Infrared ◽  
Digital Camera ◽  
Post Processing ◽  
Snow Layer ◽  
Avalanche Forecasting ◽  
The North ◽  
Nir Imaging ◽  
Snow Stratigraphy ◽  
Wind Events ◽  
Lateral Variations

AbstractDeposition of snow from precipitation and wind events creates layering within seasonal snowpacks. The thickness and horizontal continuity of layers within seasonal snowpacks can be highly variable, due to snow blowing around topography and vegetation, and this has important implications for hydrology, remote sensing and avalanche forecasting. In this paper, we present practical field and post-processing protocols for recording lateral variations in snow stratigraphy using near-infrared (NIR) photography. A Fuji S9100 digital camera, modified to be sensitive to NIR wavelengths, was mounted on a rail system that allowed for rapid imaging of a 10 m long snow trench excavated on the north side of Toolik Lake, Alaska (68°38′ N, 149°36′ W). Post-processing of the images included removal of lens distortion and vignetting. A tape measure running along the base of the trench provided known locations (control points) that permitted scaling and georeferencing. Snow layer heights estimated from the NIR images compared well with manual stratigraphic measurements made at 0.2 m intervals along the trench (n = 357, R2 = 0.97). Considerably greater stratigraphic detail was captured by the NIR images than in the manually recorded profiles. NIR imaging of snow trenches using the described protocols is an efficient tool for quantifying continuous microscale variations in snow layers and associated properties.

Experimental Studies of the Primary Zone Flow Field and Combustion Performance of a Triple Swirler Combustor

2005 ◽  
Author(s):  
Yunhui Peng ◽  
Quanhong Xu ◽  
Yuzhen Lin
Keyword(s):  
Flow Field ◽  
Experimental Studies ◽  
Fuel Injector ◽  
Lean Blowout ◽  
Combustion Performance ◽  
Primary Zone ◽  
Image Velocimetry ◽  
Aero Engine ◽  
Exit Temperature ◽  
Promising Solution

Improvement of the lean blowout limit and more uniform combustor exit temperature distribution are particularly desirable for future aero engine. A triple swirler combination plus an airblast fuel injector might be a promising solution. The design with the triple swirler plus the airblast fuel injector including design A and B was presented and investigated in this paper. Single rectangle sector module combustor was used in the experiment for lean blowout (LBO), and three cups rectangle sector combustor was used for pattern factor (PF) experiments. The LBO and PF experiment data were provided. The primary zone flow field was measured by PIV (Particle Image Velocimetry) under atmospheric pressure and temperature. The result showed that the design A was a promising design, and the primary jet played very important role for flow field of primary zone. The insight relation between flow field and combustion performance could be found out from this paper.

Fractal and Non-Fractal Surfaces in Ion Sputtering

1995 ◽  
Vol 407 ◽  
Author(s):  
A.-L. Barabási ◽  
R. Cuerno
Keyword(s):  
Nonlinear Equation ◽  
Penetration Depth ◽  
Experimental Studies ◽  
Ion Bombardment ◽  
Physical Parameters ◽  
Angle Of Incidence ◽  
Ion Sputtering ◽  
Scaling Properties ◽  
Fractal Surfaces ◽  
Experimental Parameters

ABSTRACTRecently a number of experimental studies focusing on the scaling properties of surfaces eroded by ion bombardment provided apparently contradictory results. A number of experiments report the observation of self-affine fractal surfaces, while others provide evidence about the development of a non-fractal periodic ripple structure. To explain these discrepancies, here we derive a stochastic nonlinear equation that describes the evolution and scaling properties of surfaces eroded by ion bombardment. The coefficients appearing in the equation can be calculated explicitly in terms of the physical parameters characterizing the sputtering process. We find that transitions may take place between various scaling behaviors when experimental parameters, such as the angle of incidence of the incoming ions or their average penetration depth, are varied.

A tracking algorithm to identify slab and weak layer combinations for assessing snow instability and avalanche problem type

2021 ◽  
Author(s):  
Benjamin Reuter ◽  
Léo Viallon-Galinier ◽  
Stephanie Mayer ◽  
Pascal Hagenmuller ◽  
Samuel Morin
Keyword(s):  
Snow Cover ◽  
Winter Season ◽  
Essential Element ◽  
Problem Type ◽  
Model Output ◽  
Avalanche Forecasting ◽  
Weak Layer ◽  
Problem Types ◽  
Snow Stratigraphy ◽  
Wet Snow

<p>Snow cover models have mostly been developed to support avalanche forecasting. Recently developed snow instability metrics can help interpreting modeled snow cover data. However, presently snow cover models cannot forecast the relevant avalanche problem types – an essential element to describe avalanche danger. We present an approach to detect, track and assess weak layers in snow cover model output data to eventually assess the related avalanche problem type. We demonstrate the applicability of this approach with both, SNOWPACK and CROCUS snow cover model output for one winter season at Weissfluhjoch. We introduced a classification scheme for four commonly used avalanche problem types including new snow, wind slabs, persistent weak layers and wet snow, so different avalanche situations during a winter season can be classified based on weak layer type and meteorological conditions. According to the modeled avalanche problem types and snow instability metrics both models produced weaknesses in the modeled stratigraphy during similar periods. For instance, in late December 2014 the models picked up a non-persistent as well as a persistent weak layer that were both observed in the field and caused widespread instability in the area. Times when avalanches released naturally were recorded with two seismic avalanche detection systems, and coincided reasonably well with periods of low modeled stability. Moreover, the presented approach provides the avalanche problem types that relate to the observed natural instability which makes the interpretation of modeled snow instability metrics easier. As the presented approach is process-based, it is applicable to any model in any snow avalanche climate. It could be used to anticipate changes in avalanche problem type due to changing climate. Moreover, the presented approach is suited to support the interpretation of snow stratigraphy data for operational forecasting.</p>

scholarly journals Instruments and Methods Snow Density Profiling by Nuclear Means

1966 ◽  
Vol 6 (43) ◽  
pp. 171-176
Author(s):  
Robert D. Leighty
Keyword(s):  
Soil Moisture ◽  
Field Investigation ◽  
Present Form ◽  
Snow Density ◽  
Nuclear Technique ◽  
Density Profiles ◽  
Snow Stratigraphy ◽  
Modes Of Processing ◽  
Nuclear Detectors ◽  
Nuclear Method

Abstract During the period 8–19 May 1963 a preliminary field investigation was conducted in Greenland to determine the feasibility of using a nuclear technique to determine snow and ice density profiles. A standard nuclear soil-moisture depth probe was used with two modes of processing and recording the nuclear pulses. Example data are compared with snow densities obtained by the standard weighing technique. The nuclear method was found to be feasible; however, deficiencies related to poor resolution render the probe unusable for detailed profiling of snow stratigraphy in its present form, but expected progress in nucleonics should enable improved resolution and accuracy to be achieved by improvement of nuclear detectors.

scholarly journals Convection at an isothermal wall in an enclosure and establishment of stratification

2016 ◽  
Vol 799 ◽  
pp. 448-475 ◽  
Author(s):  
T. Caudwell ◽  
J.-B. Flór ◽  
M. E. Negretti
Keyword(s):  
Experimental Studies ◽  
Vertical Plane ◽  
Flow Characteristics ◽  
Similarity Solutions ◽  
Closed Cavity ◽  
Turbulent Transition ◽  
Image Velocimetry ◽  
Entrainment Coefficient ◽  
Isothermal Wall ◽  
Wall Plume

In this experimental–theoretical investigation, we consider a turbulent plume generated by an isothermal wall in a closed cavity and the formation of heat stratification in the interior. The buoyancy of the plume near the wall and the temperature stratification are measured across a vertical plane with the temperature laser induced fluorescence method, which is shown to be accurate and efficient (precision of $0.2\,^{\circ }$C) for experimental studies on convection. The simultaneous measurement of the velocity field with particle image velocimetry allows for the calculation of the flow characteristics such as the Richardson number and Reynolds stress. This enables us to give a refined description of the wall plume, as well as the circulation and evolution of the stratification in the interior. The wall plume is found to have an inner layer close to the heated boundary with a laminar transport of hardly mixed fluid which causes a relatively warm top layer and an outer layer with a transition from laminar to turbulent at a considerable height. The measured entrainment coefficient is found to be dramatically influenced by the increase in stratification of the ambient fluid. To model the flow, the entrainment model of Morton, Taylor & Turner (Proc. R. Soc. Lond. A, vol. 234 (1196), 1956, pp. 1–23) has first been adapted to the case of an isothermal wall. Differences due to their boundary condition of a constant buoyancy flux, modelled with salt by Cooper & Hunt (J. Fluid Mech., vol. 646, 2010, pp. 39–58), turn out to be small. Next, to include the laminar–turbulent transition of the boundary layer, a hybrid model is constructed which is based on the similarity solutions reported by Worster & Leitch (J. Fluid Mech., vol. 156, 1985, pp. 301–319) for the laminar part and the entrainment model for the turbulent part. Finally, the observed variation of the global entrainment coefficient, which is due to the increased presence of an upper stratified layer with a relatively low entrainment coefficient, is incorporated into both models. All models show reasonable agreement with experimental measurements for the volume, momentum and buoyancy fluxes as well as for the evolution of the stratification in the interior. In particular, the introduction of the variable entrainment coefficient improves all models significantly.

Experimental Study on Sensitivity Damage of Offshore High-Porosity and High-Permeability Reservoir

2014 ◽  
Vol 926-930 ◽  
pp. 111-114
Author(s):  
Jun Yi Liu ◽  
Zheng Song Qiu ◽  
Wei An Huang ◽  
Yang Luo
Keyword(s):  
Experimental Studies ◽  
Wide Distribution ◽  
Development Stage ◽  
Stress Sensitivity ◽  
Laboratory Evaluation ◽  
Drilling Fluids ◽  
High Porosity ◽  
High Permeability ◽  
Intrusion Prevention ◽  
Water Sensitivity

Offshore high-porosity and high-permeability reservoirs, characterized by large pore throat, wide distribution of pore size and enriched sensitive minerals, are easily damaged due to improper use of drilling fluids and completion fluids during the development stage. A series of experimental studies were carried out on the sensitivity damage analysis including X-ray diffraction, scanning electron microscopy, mercury injection porosimetry and core flow experiment. According to the laboratory evaluation results, the reservoir SZLF of high-porosity and high-permeability existed strong water sensitivity and mid to strong stress sensitivity. Furthermore, shielding and temporary plugging technique applied for reservoir protection was put forward, and laboratory tests showed that it had a better effect on solid intrusion prevention.

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