Numerical and Experimental Investigation of Thermal Signatures of Buried Landmines in Dry Soil

2005 ◽  
Vol 128 (5) ◽  
pp. 484-494 ◽  
Author(s):  
F. Moukalled ◽  
N. Ghaddar ◽  
H. Kabbani ◽  
N. Khalid ◽  
Z. Fawaz
Keyword(s):  
Experimental Investigation ◽  
Numerical Model ◽  
Measurement Techniques ◽  
Infrared Camera ◽  
Soil Surface ◽  
Radiant Heat ◽  
Transient Temperature ◽  
Numerical Predictions ◽  
Soil Temperatures ◽  
Thermal Signature

This paper reports a numerical and experimental investigation conducted to study the thermal signature of buried landmines on soil surface. A finite-volume-based numerical model was developed to solve the unsteady three-dimensional heat transport equation in dry homogeneous soil with a buried mine. Numerical predictions of soil thermal response were validated by comparison with published analytical and numerical values in addition to data obtained experimentally. Experiments were performed inside an environmental chamber and soil temperatures were measured during cooling, using two measurement techniques, after exposing the soil surface to a radiant heat flux for a specified period. In the first technique, the temporal variation of the surface and internal soil temperatures were recorded using thermocouples. In the second technique, the soil surface temperature was measured using an infrared camera that revealed the thermal signature of the mine. The transient temperature profiles generated numerically agreed with measurements, and the difference between predicted and measured values was less than 0.3°C at both the soil surface and in depth. The accurate matching of numerical and IR images at the surfaces was found to strongly depend on the use of a smaller soil thermal conductivity at the surface than at greater depths. The numerical model was used to predict the dependence of the peak thermal contrast on time, depth, and heating period. The thermographic analysis, when combined with numerical predictions, holds promise as a method for detecting shallowly buried land mines.

Numerical and Experimental Investigation of Thermal Signatures of Buried Landmines in Dry Soil

2005 ◽  
Author(s):  
F. Moukalled ◽  
N. Ghaddar ◽  
H. Kabbani ◽  
N. Khaled ◽  
Z. Fawaz
Keyword(s):  
Experimental Investigation ◽  
Numerical Data ◽  
Soil Surface ◽  
Radiant Heat ◽  
Balance Model ◽  
Transient Temperature ◽  
Numerical Predictions ◽  
Dry Soil ◽  
The Difference ◽  
Thermal Signature

This paper reports a numerical and experimental investigation conducted to study the surface thermal signature of buried landmines. Numerical predictions are obtained by solving an unsteady three-dimensional energy balance model for heat transport in dry soil with a buried mine using the conservative finite-volume method. The model is validated by comparing generated results against published analytical and numerical data in addition to indoor measurements performed on dry soil inside an environmental chamber. The thermal signatures are observed while cooling takes place after exposing the soil surface to a radiant heat flux for a specified period. Transient temperature profiles produced numerically agree well with thermocouple measurements recorded at shallow soil depths and with surface IR images. The difference between predicted and measured surface temperatures is less than 0.4°C and the difference in thermal signature is less than 0.3°C. Sit in. The numerical model is also used to predict perturbations of the expected thermal signatures that are compared to the real (measured) ones from the IR images. The thermographic analysis shows good promise as a method for detecting shallowly buried land mines where not only the temperature difference or contrast images generated by the thermal signatures are matched between the IR images and the simulation images with high accuracy, but also the absolute temperatures for many images generated at discrete time intervals.

scholarly journals Experimental Investigation of Two-Degree-of-Freedom VIV of Circular Cylinder With Low Equivalent Mass and Variable Natural Frequency Ratio

2013 ◽  
Author(s):  
Narakorn Srinil ◽  
Hossein Zanganeh ◽  
Alexander Day
Keyword(s):  
Experimental Investigation ◽  
Numerical Model ◽  
Circular Cylinder ◽  
Natural Frequency ◽  
Frequency Ratio ◽  
Cross Flow ◽  
Number Range ◽  
Numerical Predictions ◽  
Equivalent Mass ◽  
Wake Oscillators

This paper presents an experimental investigation and validation of numerical prediction model for a 2-DOF VIV of a flexibly mounted circular cylinder by also accounting for the effect of geometrically nonlinear displacement coupling. A mechanical spring-cylinder system, achieving a low equivalent mass ratio in both in-line and cross-flow directions, is tested in a water towing tank and subject to a uniform steady flow in a sub-critical Reynolds number range of about 2000–50000. A generalized numerical model is based on double Duffing-van der Pol (structure-wake) oscillators which can capture the structural geometrical coupling and fluid-structure interaction effects through system cubic and quadratic nonlinearities. Experimental results are compared with numerical predictions in terms of response amplitudes, lock-in ranges and time-varying trajectories of cross-flow/in-line motions. Some good qualitative and quantitative agreements are found which encourage the use of the proposed numerical model subject to calibration and tuning of empirical coefficients. Various features of figure-of-eight orbital motions due to dual resonances are observed experimentally as well as numerically, depending on the natural frequency ratio of the oscillating cylinder.

Numerical Predictions on the Soil Thermal Effect Under Surface Fire Conditions

1997 ◽  
Vol 7 (1) ◽  
pp. 51 ◽  
Author(s):  
LA Oliveira ◽  
DX Viegas ◽  
AM Raimundo
Keyword(s):  
Temperature Distribution ◽  
Flame Front ◽  
Radiation Effects ◽  
Control Volume ◽  
Ground Surface ◽  
Soil Surface ◽  
Heat Transfer Process ◽  
Maximum Temperature ◽  
Transient Temperature ◽  
Numerical Predictions

A control volume numerical method is used to predict the temperature distribution inside a soil extent, the surface of which has been swept by a two-dimensional flame front with pre-defined velocity and temperature distributions. Natural and forced convection, as well as radiation effects are included in the specification of the soil surface thermal boundary condition. The flame residence time and maximum temperature are identified as two major parameters to characterize the flame front. As expected, the heat penetration depth is confined to the near vicinity of the soil surface. Moreover, horizontal heat conduction throughout the soil has not always a significant effect on its global, transient temperature distribution. The influence of wind velocity and of soil thermal diffusivity upon its temperature distribution are analysed. Radiation is the dominant contribution in the whole heat transfer process between flame and ground surface.

Accuracy of Wearable Sensor Technology in Hand Goniometry: A Systematic Review

Hand ◽  
2021 ◽  
pp. 155894472110146
Author(s):  
Francisco R. Avila ◽  
Rickey E. Carter ◽  
Christopher J. McLeod ◽  
Charles J. Bruce ◽  
Davide Giardi ◽  
...  
Keyword(s):  
Systematic Review ◽  
Range Of Motion ◽  
Health Care Professionals ◽  
Inertial Sensors ◽  
Measurement Techniques ◽  
Infrared Camera ◽  
Wearable Devices ◽  
Sensor Technology ◽  
Accuracy Evaluation ◽  
Wearable Sensor

Background Wearable devices and sensor technology provide objective, unbiased range of motion measurements that help health care professionals overcome the hindrances of protractor-based goniometry. This review aims to analyze the accuracy of existing wearable sensor technologies for hand range of motion measurement and identify the most accurate one. Methods We performed a systematic review by searching PubMed, CINAHL, and Embase for studies evaluating wearable sensor technology in hand range of motion assessment. Keywords used for the inquiry were related to wearable devices and hand goniometry. Results Of the 71 studies, 11 met the inclusion criteria. Ten studies evaluated gloves and 1 evaluated a wristband. The most common types of sensors used were bend sensors, followed by inertial sensors, Hall effect sensors, and magnetometers. Most studies compared wearable devices with manual goniometry, achieving optimal accuracy. Although most of the devices reached adequate levels of measurement error, accuracy evaluation in the reviewed studies might be subject to bias owing to the use of poorly reliable measurement techniques for comparison of the devices. Conclusion Gloves using inertial sensors were the most accurate. Future studies should use different comparison techniques, such as infrared camera–based goniometry or virtual motion tracking, to evaluate the performance of wearable devices.

scholarly journals Transient Infrared Measurement of Laser Absorption Properties of Porous Materials

2016 ◽  
Vol 16 (3) ◽  
pp. 167-173
Author(s):  
Andrzej Marynowicz
Keyword(s):  
Laser Beam ◽  
Building Materials ◽  
Optimization Technique ◽  
Infrared Camera ◽  
Transient Temperature ◽  
Absorption Properties ◽  
Porous Building Materials ◽  
Laser Absorption ◽  
Infrared Measurement ◽  
Heating Up

Abstract The infrared thermography measurements of porous building materials have become more frequent in recent years. Many accompanying techniques for the thermal field generation have been developed, including one based on laser radiation. This work presents a simple optimization technique for estimation of the laser beam absorption for selected porous building materials, namely clinker brick and cement mortar. The transient temperature measurements were performed with the use of infrared camera during laser-induced heating-up of the samples’ surfaces. As the results, the absorbed fractions of the incident laser beam together with its shape parameter are reported.

A physically-based soil surface model and its combination with numerical models for predicting bare-soil evaporation rates

2021 ◽  
Author(s):  
Xiaocheng Liu ◽  
Chenming Zhang ◽  
Yue Liu ◽  
David Lockington ◽  
Ling Li
Keyword(s):  
Numerical Model ◽  
Surface Resistance ◽  
Numerical Models ◽  
Soil Column ◽  
Soil Surface ◽  
Bare Soil ◽  
Water Vapor Transport ◽  
Surface Model ◽  
Vapor Flow ◽  
Physically Based

<p>Estimation of evaporation rates from soils is significant for environmental, hydrological, and agricultural purposes. Modeling of the soil surface resistance is essential to estimate the evaporation rates from bare soil. Empirical surface resistance models may cause large deviations when applied to different soils. A physically-based soil surface model is developed to calculate the surface resistance, which can consider evaporation on the soil surface when soil is fully saturated and the vapor flow below the soil surface after dry layer forming on the top. Furthermore, this physically-based expression of the surface resistance is added into a numerical model that considers the liquid water transport, water vapor transport, and heat transport during evaporation. The simulation results are in good agreement with the results from six soil column drying experiments.  This numerical model can be applied to predict or estimate the evaporation rate of different soil and saturation at different depths during evaporation.</p>

scholarly journals Crop residues on short-term CO2 emissions in sugarcane production areas

2013 ◽  
Vol 33 (4) ◽  
pp. 699-708 ◽  
Author(s):  
Mariana M. Corradi ◽  
Alan R. Panosso ◽  
Marcílio V. Martins Filho ◽  
Newton La Scala Junior
Keyword(s):  
Co2 Emissions ◽  
Field Experiments ◽  
Crop Residues ◽  
Soil Surface ◽  
Dry Mass ◽  
Agricultural Crop ◽  
Short Term ◽  
Sugarcane Production ◽  
Soil Temperatures ◽  
Production Areas

The proper management of agricultural crop residues could produce benefits in a warmer, more drought-prone world. Field experiments were conducted in sugarcane production areas in the Southern Brazil to assess the influence of crop residues on the soil surface in short-term CO2 emissions. The study was carried out over a period of 50 days after establishing 6 plots with and without crop residues applied to the soil surface. The effects of sugarcane residues on CO2 emissions were immediate; the emissions from residue-covered plots with equivalent densities of 3 (D50) and 6 (D100) t ha-1 (dry mass) were less than those from non-covered plots (D0). Additionally, the covered fields had lower soil temperatures and higher soil moisture for most of the studied days, especially during the periods of drought. Total emissions were as high as 553.62 ± 47.20 g CO2 m-2, and as low as 384.69 ± 31.69 g CO2 m-2 in non-covered (D0) and covered plot with an equivalent density of 3 t ha-1 (D50), respectively. Our results indicate a significant reduction in CO2 emissions, indicating conservation of soil carbon over the short-term period following the application of sugarcane residues to the soil surface.

Rewetting Analysis of Hot Moving Surface by Round Water Jet Impingement

2018 ◽  
Author(s):  
Avadhesh Kumar Sharma ◽  
Mayank Modak ◽  
Santosh K. Sahu
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Thermal Imaging ◽  
Transient Temperature ◽  
Axial Distance ◽  
Initial Surface ◽  
Moving Plate ◽  
Thermal Imaging Camera ◽  
Plate Velocity ◽  
Imaging Camera

Impinging jets are commonly utilized in the run-out table (ROT) cooling in the hot rolling process in steel manufacturing industries. The phenomenon of rapid cooling of a sufficiently hot surface is termed as the quenching. The present paper reports the rewetting behavior of 0.15 mm thick hot moving stainless steel foil (SS-304) by circular impinging jet from bottom side through experimental investigation. The transient temperature of the hot foil is recorded by using thermal imaging camera (A655sc, FLIR system). Tests are performed for a varied range of Reynolds number (Re = 2500–10000), nozzle to plate distance (z/d = 6), moving plate velocity (0–40 mm/s) and initial surface temperature 500±10 °C. Transient temperature obtained from thermal imaging camera is used to evaluate rewetting time and rewetting velocity. Based on the experimental investigation correlation has been proposed to predict non-dimensional rewetting velocity as a function of various parameters, namely, Reynolds number, non-dimensional axial distance and moving plate velocity.

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