Papers by Keyword: Subsurface

Abstract: Subsurface photoacoustic imaging with high resolution is utilized to image the teeth layer due to periodontal tissue inflammation. The aim of this imaging method is to determine the difference between healthy teeth and teeth affected by inflammation based on the acoustic signals obtained. An 808 nm diode laser is used as a radiation source, a condenser microphone is used as a detector, and computer numerical control (CNC) is used for the sample scanning process. The samples were healthy and inflamed Sprague-Dawley rat teeth. The average acoustic intensity of healthy teeth layers was 60.200.9 dB for enamel and 52.210.9 dB for dentin, while the average acoustic intensity of inflammation-affected teeth layers was 93.140.4 dB for enamel and 84.840.4 dB for dentin. Based on the histogram results obtained, the generative adversarial network (GAN) method can be used to improve photoacoustic image resolution to become more detailed. The study shows that high-resolution subsurface photoacoustic imaging can be utilized to image teeth layers.

Abstract: Information of subsurface stratigraphy is needed during the process of preparing multi-story buildings to avoid problems in determining the level of multi-story building piles. This research was conducted using the geoelectric method to study the subsurface stratigraphic conditions in the area. Based on the measurement results, we find an overview of the subsurface stratigraphic conditions consisting of soil in the first layer with resistivity values ​​ranging from 305 to 570 Ωm, the soil in the study area is red-yellow, namely podsolic soil mixed with sand and gravel. The second layer is clay layer by water saturated with resistivity values ​​between 15 to 44 Ωm, and the third layer with resistivity values ​​varying from 112 to 341 detected from the surface is sandy clay. Insertion of coal at the first measurement point was detected buried at a depth of 17 m from the surface with a resistivity value of 962 Ωm.

Abstract: The major objective of the EU Horizon 2020 project “BioMOre” is the technical realization of indirect in situ leaching of Kupferschiefer sandstone and black shale ore by a ferric iron lixiviant generated by a mixed culture of autotrophic, acidophilic, iron-oxidizing bacteria and archaea in a ferric iron-generating bioreactor (FIGB). These organisms could colonize the deeply buried geological formations even under anaerobic conditions as most are able to grow by coupling the reduction of ferric iron to the oxidation of reduced sulfur compounds in the absence of oxygen. Development of an inhibition protocol to eliminate these allochthonous microbial bioreactor populations subsequent to the completion of in situ bioleaching was therefore investigated. Column bioleaching experiments using a laboratory-scale FIGB confirmed not only that metals were solubilised from both the sandstone and shale ores, but also that significant numbers of bacteria were released from the FIGB. The efficacy of 13 different chemical compounds in inhibiting microbial iron oxidation has been tested at different concentrations in shake flask and FIGB-coupled columns. Iron-oxidation activity, microcalorimetrically-determined activity and ATP measurements, in combination with microscopic cell counts and biomolecular analysis (T-RFLP, qPCR), plate counts and most-probable-number (MPN), were used to monitor the inhibiting effects on the acidophiles. Complete inhibition of metabolic activity of iron-oxidizing acidophiles was achieved in the presence of 0.4 mM formate, 300 mM chloride, 100 mM nitrate, 10 mM of primary C₆ to C₈ alcohols, 100 mM 1-butanol, 100 mM 1-pentanol, 0.1 mM SDS or 0.35 mM benzoic acid. No inhibition was found for 0.6 mM acetic acid and 200 mM methanol. Based on these results a recipe for the chemical composition of the “decommissioning solution” is proposed.

Abstract: An assessment of subsurface profile of a study area at Nusajaya. Johor was conducted using 2D resistivity method. The aims of the study are to determine the subsurface profile hence contouring the appearance of outcrop by 2D resistivity imaging. Subsurface structure can be delineated based on the physical and chemical parameter which is apparent resistivity of the medium. A survey line of 80m and minimum 2m electrode spacing was adopted using Pole-dipole array. Data acquisition on the survey line was completed and processed by using Res2Dinv software. The inversion model resistivity shows sandstone contains iron mineral (30-250 ohm-m) and weathered sandstone (500-1000 ohm-m). The lower part of the layer represents sandstone and siltstone exhibit high resistivity values of 1500-5000 ohm-m. The range from 30-1000 ohm-m correspond to the grade IV and V of sandstone in the actual profile. Meanwhile, the high range of the resistivity value matched the material with weathering grade II and III in ground mass. The deterioration of most physical properties was associated with the increase number of weathering grade.

Abstract: Various non-destructive testing and evaluation (NDTE) techniques are in use by the aviation industry. Thermal imaging as an NDTE tool for composite material is becoming an effective methodology. In this research, a direct energy method approach to active thermal imaging is applied with test specimen placed between the heating source and the camera to take only one diagnostics snap per unit area of region of interest (ROI). Purpose of this study is to assess the utility of direct method as a reliable NDTE technique during aerospace inspections as a quick ‘Go / No Go’ tool for the detection of sub-surface delamination in multilayered composite sheets. The research presents a quantitative comparison of temperature profiles as well as qualitative analysis of 2D active infrared thermo graphic testing of glass fiber epoxy to detect sub-surface delamination. The experimental results are in close agreement with the actual locations of delamination in test samples. The technique may serve as a reliable tool to quickly categorize the component under inspection. However, the size of delamination could not be ascertained with acceptable accuracy in this study, possibly due to the spread of epoxy to the delaminated regions during preparation of defective samples.

Abstract: Jilin Provincial Academy of Agricultural Machinery initiated studies in 2000 to develop the methodology for successful application of subsurface drip irrigation (SDI) for corn production on the deep silt loam soils of the northeast plains, China. Irrigation water use for corn can be reduced by 37–52% when using SDI compared with more traditional forms of irrigation in the region. Irrigation frequency has not been a critical issue when SDI is used for corn production on the deep silt loam soils of the region. A dripline spacing of 1.5 m has been found to be most economical for corn grown in 0.76 m spaced rows. Nitrogen fertigation was a very effective management tool with SDI, helping to maximize corn grain yield, while obtaining high efficiencies of nitrogen and water use. The research SDI systems have been utilized since 2000 without replacement or major degradation. SDI systems lasting 10–20 years are cost competitive for corn production with the more traditional forms of irrigation in the northeast plains for certain field sizes.

Abstract: With the continuing growth in influence of near surface geophysics, the research of the subsurface structure is of great significance. Geophysical imaging is one of the efficient computer tools that can be applied. This paper utilize the inversion of potential field data to do the subsurface imaging. Here, gravity data and magnetic data are inverted together with structural coupled inversion algorithm. The subspace (model space) is divided into a set of rectangular cells by an orthogonal 2D mesh and assume a constant property (density and magnetic susceptibility) value within each cell. The inversion matrix equation is solved as an unconstrained optimization problem with conjugate gradient method (CG). This imaging method is applied to synthetic data for typical models of gravity and magnetic anomalies and is tested on field data.

Abstract: Specimens of Al-and Ti-alloys and turbine blades of Ni-based alloy were considered in the case of crack origination at the surface, subsurface, and at the inner surface of turbine blades. Aircraft structures such as hydrocylinders of Al-based alloy and landing gear of high-strength-steel were also considered. There was used acoustic emission (AE) monitoring to fix moment of crack occurring and, then, analyzing its growth. Fracture surface features appearance was compared with AE-signals regularities based on fractographic analyses. To indicate the crack origination moment it was introduced α-criterion. This criterion characterized drastically increase in summarized AE-signals appearing in dependence on cyclic loads number. During crack propagation, there was used Elber-portion of opened crack to register AE-signals in cyclic loads. It was demonstrated crack increment in unloading portion of cyclic loads with fatigue striations formation. Two aircraft structures of hydrocylinders and shock strut of landing gear were tested on the special test facilities and AE-monitoring was conducted. Effectiveness of α-criterion using for crack registration in the high-cycle fatigue regime was demonstrated applicably to crack appearance on the internal surface and subsurface. The discovered dependences of summarized AE-signals on number of cycles were compared with fracture surface patterns and briefly discussed.

Abstract: To reduce safe distance such as inhabited building distance (IBD), a new type magazine, which is referred to as a subsurface magazine, has been proposed and the explosion effects have been discussed. We have conducted explosive tests by using relatively large scale models (23 kg and 78 kg in mass) and examined mass effect (scale effect) of blast waves caused by explosion of high explosives. The magazines were composed of a arch-type explosive storage room with a line hinge along the top of the roof of the wall, a square passage way to ground which will release the blast wave. Explosion hazards from the explosion of subsurface magazines were collected to understand the characteristics of airblast, fragments, and ground shocks. Safety criteria for the subsurface magazine are discussed based on the experimental results.

Abstract: In this paper, the characteristics of high speed grinding of advanced ceramics, including alumina, alumina-titania, zirconia, silicon nitride and silicon carbide, were reviewed. The associated material removal mechanisms were discussed. Pragmatic technologies for the high speed grinding of advanced ceramics were also presented.