Front Slope Research Articles

RECYCLING OF MATERIALS FROM THE EXCAVATION OF THE "POČITELJ" TUNNEL AND INCORPORATION OF THE OBTAINED PRODUCTS IN THE TUNNEL THROUGH CONCRETE AND BLINDING LAYER

In civil engineering or road construction, especially when constructing tunnels, large quantities of excavated material are created. In many cases, this material, if properly treated and processed, can be recycled and reused on site. If this material is not treated as planned from the beginning of the project, but is taken to the landfill and mixed with bad material or construction waste, then when the need for it arises, it is difficult to separate it and return it to the construction process. In the simplest case, the material can be used as an embankment to the extent that it meets the requirements regarding the quality of the embankment material. Better quality material can often be recycled to make fractions for various types of concrete, buffer aggregates or decorative stone walls (architectural stone). In the current example of the "Počitelj" tunnel, through tests of fractions, definition of recipes, recycled material from tunnel excavation was successfully used as aggregate for shotcrete, concrete for inner lining and construction, buffer, bedding for laying pipes and making front slopes from crushed stone. This reduced the purchase and transport of aggregates from local quarries to the minimum possible, thus saving resources, with financial benefit. In summary, through this example, it can be noted that the reuse of tunnel excavation will play an important role for future tunnel projects due to environmental and economic reasons. Keywords: tunnel, excavation, limestone, concrete, blinding layer, recycling

Current Issues Related to Anthropometry in Engineering

Anthropos and Metrikos both mean "human" in Greek, which is where the term anthropometry comes from. Anthropometry is employed in a variety of fields, including apparel and textile design. For anthropometric evaluations, a current, thorough, and community-specific anthropometric normative-reference standard is necessary. In health care, ergonomic design is utilised to reduce pain and illness. Misalignments between humans and machines result in pain, accidents, biomechanical stress, tiredness, and musculoskeletal injuries. Designing for the anthropometrics of end users improves long-term viability. The human body comes in a wide range of sizes and shapes. Manual measurement and 3D scanning procedures, on the other hand, are inefficient and expensive, making precise body measurements difficult. This is especially true for head-worn medical devices. Manual measurement and 3D scanning are inefficient and expensive, making precise body measurements difficult. Grip strength and force were determined using hand measurements. Anthropometric parameter estimate is more precise when a 3D model is used to boost pinnae features. While numerous anatomical features have been gathered to aid in the ergonomic design of wearable devices, there is still a lot more work to be done. In three dimensions, the segment masses and torso Centre of Mass (COM) may be calculated. Researchers tracking mobility would benefit greatly from the ability to locate the body COM using a weighted sum of segment masses. Design features such as comfort and usefulness are crucial. Ergonomic characteristics like taller seats with front slopes and saddle chairs encourage good posture, movement, and alternation. In the creation of wearable technologies, using outdated anthropometric reference standards may be insufficient. This review discuses common issues related to anthropometry in engineering which includes the human body, anthropometric parameters, anthropometric measurements, the force plate method, ergonomic design, and body dimension. The goal is to give a broad overview of the subject.

Experimental study of internal solitary wave evolution beneath an ice keel model

Internal solitary waves (ISWs) propagating in polar seas are affected by the sea ice at upper boundary of seas and thus exhibit complex evolution characteristics. Herein, spatiotemporal changes in the wave element, flow field, and energy of ISWs beneath an ice keel model were investigated to examine the evolution of ISWs. For this purpose, laboratory experiments were conducted using dye-tracing labeling, conductivity probes, Schlieren technology, and particle image velocimetry. The results show that ice keel causes an increase in the thickness of the pycnocline and even the occurrence of breaking and internal surging of ISW. Additionally, the waveform becomes narrower or wider at different positions, and wave amplitude and speed decrease, with a maximum reduction 30%–40%. Furthermore, the ice keel strengthens the shear of the ISW-induced flow field, generating vortices and mixing. The energy of ISWs undergoes internal conversion majorly at the front slope of the ice keel, while energy dissipation occurs largely at the back slope, with dissipation rates as high as 60%.

Analisis Of Upgrading Low-Crested Structures As An Adaptation Measure To Climate Change For Coastal Protection: A Hybrid Approach

Coastal zones have consistently been among the most appealing settlement areas due to their proximity to the sea, rich natural resources, and the high quality of life they offer (Lamberti et al., 2005). However, these regions are affected by climate change impacts, such as sea-level rise, storm surges, and an increased intensity of extreme weather events (Burcharth et al., 2014). Traditional low-crested rubble mound breakwaters are commonly used to protect coastal areas from wave damage. However, it is expected that the variability of climate conditions will induce a loss of functionality and structural integrity in the coming decades. Coastal communities and coastal managers, within the framework of sustainable development, are demanding new approaches that include not only the preservation of the hydraulic performance of the breakwaters, but also other factors, including social and environmental impacts. These requests significantly affect the traditional way to conceive those structures to be integrated into the coastal landscape. To cope with the variation of climate drivers, existing low-crested breakwaters must be adapted to accommodate social demands and environmental issues. Therefore, upgrading and maintaining the existing rubble-mound breakwater is a hot topic in coastal engineering, and deserves special attention due to the possible intensification of external loads resulting from the impacts of climate change (Stagnitti et al., 2023). Upgrading can be done by modifying the structure profile and/or adding structure elements (Burcharth et al., 2014). In 2011, Cappietti provided curves for the functional design of submerged breakwaters to be used in place of preexisting emergent breakwaters. Burcharth et al. (2014) explained that the best way to improve the structure is to put an additional layer of protection on the front slope, as long as the foreshore has a mild slope of around 1:100. But if the foreshore becomes steeper because of erosion, then a front berm will also be needed. Stagnitti et al. (2022) introduced a novel methodology based on the calculation of the failure probability during a lifetime due to independent failure modes. Their method was employed to evaluate the performance of upgraded breakwaters in response to climate change. Estimating the wave overtopping of both existing and upgraded breakwaters is essential for designing upgrade options that can ensure the safety of port operations. Stagnitti et al. (2023) applied the numerical model IH2VOF, which was calibrated using experimental data, to study the wave overtopping of damaged and upgraded rubble-mound breakwaters. The present work examines the feasibility of converting emerged rubble-mound breakwaters into submerged breakwaters to minimize their detrimental environmental effects. To achieve this goal, an investigation was conducted to evaluate the hydraulic performance of submerged breakwaters that are created by lowering the crest of existing emerged breakwaters. Additionally, two-dimensional numerical simulations were performed using IH2VOF to investigate wave interactions with the structures.

Wave and Roller Transformation Over Barred Bathymetry

AbstractThe cross‐shore transformation of breaking‐wave roller momentum and energy on observed barred surfzone bathymetry is investigated with a two‐phase Reynolds Averaged Navier Stokes model driven with measured incident waves. Modeled wave spectra, wave heights, and wave‐driven increases in the mean water level (setup) agree well with field observations along transects extending from 5‐m water depth to the shoreline. Consistent with prior results the roller forcing contributes 50%–60% to the setup, whereas the advective terms contribute ∼20%, with the contribution of bottom stress largest (up to 20%) for shallow sandbar crest depths. The model simulations suggest that an energy‐flux balance between wave dissipation, roller energy, and roller dissipation is accurate. However, as little as 70% of the modeled wave energy ultimately dissipated by breaking was first transferred from the wave to the roller. Furthermore, of the energy transferred to the roller, 15%–25% is dissipated by turbulence in the water column below the roller, with the majority of energy dissipated in the aerated region or near the roller‐surface interface. The contributions of turbulence to the momentum balance are sensitive to the parameterized turbulent anisotropy, which observations suggest increases with increasing turbulence intensity. Here, modeled turbulent kinetic energy dissipation decreases with increasing depth of the sandbar crest, possibly reflecting a change from plunging (on the steeper offshore slope of the bar) to spilling breakers (over the flatter bar crest and trough). Thus, using a variable roller front slope in the roller‐wave energy flux balance may account for these variations in breaker type.

Sedimentary evolutionary processes, architecture, and sedimentary model of a lobate shallow-water delta: insights from flume simulation experiments

By using equipment such as time-lapse cameras and 3D laser scanners, this study conducted flume simulation experiments to obtain topographic elevation, the amount of sediment increment, sedimentary cross sections, and other related data and diagrams. Quantitative software was then utilized for sedimentological analysis to clarify the depositional evolution, architecture, and depositional model of lobate shallow-water deltas. The research results show that under the influence of hydraulic conditions and main distributary channels, lobate shallow-water deltas primarily undergo three evolution stages: initial channel formation, distributary channel system formation, and continuous stable evolution stage. The architecture elements of lobate shallow-water deltas can be divided into distributary channels dominated by channel deposition, proximal river mouth bars, transitional bars, and distal bars. The lateral composition and downstream deposition of the river-bar combination are the main structural units of the shallow water delta. The proximal profile distributary channels exist in the form of thick channel sand bodies with multiple repetitive intercalation cycles, and thick proximal bar deposits form on both sides of the distributary channels. The bifurcation of distributary channels in the middle profile leads to a reduction in channel scale, while large-scale proximal bars still develop on both sides of the channel. In the distal profile, a substantial river mouth bar complex is formed at the break of the delta front slope, and with the gradual progradation of the delta, the river mouth bar deposition zone becomes flattened. Based on the insights of the flume simulation experiments, a sedimentary model for lobate shallow-water delta was established.

Frontal slope: A new measure of ocean fronts

Ocean fronts, as typical marine phenomena, significantly impact the marine environment and the distribution of organisms. However, the research on their tilted structure is limited. This study considered the frontal slope as a key parameter for describing the tilting characteristics of ocean fronts. A novel method, based on high-resolution in situ observations and reanalysis data, was proposed to extract global frontal slopes using contour lines and surfaces. To validate this approach, a mathematical model was developed for the oceanic front slope and verified through in situ observations. The frontal slope equation produced reliable results, indicating that the front tilting primarily arises from shear flow and density differences. Furthermore, a modified oceanic front gradient parameter was proposed based on the frontal slope, and its significance in understanding the impacts of ocean fronts on underwater acoustic propagation was validated through numerical simulation and statistical analysis. The distribution characteristics of frontal slope for ocean fronts on a global scale were analyzed for the first time. Marginal ice zone fronts had the highest slope (>1.5 m/km), followed by tidal mixing fronts, western boundary current fronts, and water mass convergence fronts (1–1.5 m/km). In contrast, upwelling fronts and estuarine plume fronts generally had slopes below 1 m/km. This parameter provides a new perspective on ocean front systems and their influence on dynamic structures and ecological resource distributions. This study helps in a comprehensive understanding of the tilting characteristics of the ocean front and their implications.

Reliability of Municipal Solid Waste Landfills within the Eurocode Framework

Municipal solid waste (MSW) landfill slope failures can have significant consequences for the economy, environment, and human health. One potential cause of slope failure is insufficient reliability, resulting from inadequate design. The usual practice in the design of MSW landfills involves utilizing established geotechnical codes, such as Eurocode 7 (EC7), to perform slope stability assessments. Considering the substantial heterogeneity of MSW relative to soil, questions arise regarding the justification of such an approach in the design of MSW landfills. This study examines the suitability of applying EC7 in MSW landfill design, analyzing the stability and reliability of landfill slopes across various heights, front slope angles, design approaches, and consequence classes. This study finds that, in most cases considered, EC7 does not ensure an adequate level of reliability for MSW landfill slopes. Therefore, it is suggested that EC7 should be complemented with specific guidelines for incorporating MSW in geotechnical analyses to achieve the desired structural reliability. Adopting this strategy will not only enhance the reliability of landfill design but also promote the development of solutions that are economically and environmentally sustainable.

Landslide control in the excavation of a shallowly buried tunnel with a large front slope

The tunnel with a large front slope is a common type of entrance in mountain tunnels. Excavation of this type of tunnel disrupts the original balance of the slope, which can easily lead to landslides or collapses. It is therefore important to choose suitable support for early reinforcement. This paper presents a case study of landslide control during the tunnelling of a shallowly buried tunnel with a large front slope. Three types of pre-support, including anti-slide pile, pipe roof and surface grouting, were used to control the landslide. In addition, a three-dimensional analysis was carried out to investigate the reinforcing effect of single and multiple pre-supports on the landslide and tunnel structure. The results showed that the deformation of the landslide and tunnel structure at the end of the entrance was the greatest, that is, the most dangerous, and the maximum slope displacement without pre-support was 15.1 cm. In tunnel structures, the arch area was the most prone to instability, while the bottom area did not experience significant deformation. The horizontal displacement control effect of the landslide body was ranked from strong to weak as surface grouting, pipe roof, and anti-slide pile, which is a decrease of 4.8%, 20.5% and 40.8% compared to the maximum displacement. While the vertical displacement control effect of the landslide was ranked from strong to weak as pipe roof, surface grouting, and anti-slide pile, which is a decrease of 4.3%, 45.1% and 63.7% compared to the maximum displacement. The reinforcement effect when three types of pre-supports were applied simultaneously was basically equal to the sum of the reinforcement effects when each pre-support was applied separately. This is mainly due to the different reinforcement mechanisms and areas of the three pre-supports, resulting in better overall effects.

Geological challenges and stabilization strategies for phyllite rock slopes: a case study of Guang-Gansu expressway in Western China.

The increased occurrence and severity of natural disasters, such as landslides, have impacted the stability of phyllite rock slopes in the complex geological regions of Western China. This situation presents significant challenges for infrastructure development in the area. This study investigates the upper span bridgehead slope of Guang-Gansu expressway K550 + 031 as a case study to analyze the sliding failure mechanism of thousand rock slopes in the seismic fault zone and the supporting structure failure through field investigation and exploration. The analysis shows that the slope's rock mass is extensively fractured, primarily influenced by the Qingchuan fault zone. This geological activity leads to slope instability, worsened by seasonal rainfall. The phyllite undergoes alternating dry and wet cycles, weakening its mechanical strength, forming cracks, and accelerating slope displacement, subsidence, and cracking. This results in front slope instability, followed by gradual backward and step-by-step traction sliding deformation on both sides. The geological structure and seasonal rainfall damage the original bolt-grid beam-supporting structure. To address this issue, an anti-slide pile combined with a grid beam treatment method is proposed, and its effectiveness is verified through deep displacement monitoring. This study emphasizes the significance of integrating geological structure and seasonal rainfall impacts into infrastructure design within complex geological areas, ensuring slope and supporting structure stability.

Rogowski coil-based autonomous fault management strategy using Karen Bell Transformation for earthed active distribution networks

This paper introduces fault type identification, fault section selection, and fault phase selectivity using a Karen Bell Transformation matrix in earthed distribution grids coupled with Doubly Fed Induction Generator (DFIG). Rogowski Coil’s (RC) model is estimated using a system identification toolbox to obtain the precise terminal voltage. This model is calculated and verified using experimental results for the RC’s primary input current and output voltage. Then, the estimated voltage relies on the current signals in the measuring point. The transient slope of the ground and aerial modes voltages is extracted during the fault to classify the fault type, discriminate the fault section and identify the faulted phase in every cycle. Further, earth faults are detected using ground and phase faults using aerial modes. The relative polarity of the front slopes at the terminals of each section created by the fault voltage is extracted to perform faulty section discrimination. The value of aerial modes is used to identify the defective phase selectivity. The overall protection selectivity function’s integration procedure with modified autonomous control is proposed for earthed distribution systems. The Transient Selectivity Function (TSF) was presented in unearthed and compensated grids in the literature. After estimating the RC voltage output at each agent, the discrete Fourier transform (DFT) phasor extraction is done. Different standard fault cases and system conditions are investigated to evaluate the proposed scheme’s behavior. Simulation results are designed using the ATP-EMTP program. The simulation results obtained validate the effectiveness of the scheme proposed in this work.

An improved subthreshold swing expression accounting for back-gate bias in FDSOI FETs

In a MOSFET transistor, the subthreshold swing defines the switching efficiency, and the associated slope factor, or so-called body factor, is a critical parameter in charge-based models. However, in an advanced Fully-Depleted Silicon-On-Insulator (FDSOI) process, the slope factor is influenced by a strong back gate coupling due to a thin buried oxide (BOX). A conventional constant expression cannot describe the slope factor at various back-gate voltages. Therefore, this paper proposes a general slope factor expression for front- and back-gate transfer characteristics of long-channel FDSOI MOSFETs in a strong gate coupling. The proposed expression is a continuous function of the surface potential difference between the front and back sides, which explains the slope factor behavior versus the back-gate voltage. Besides, the systematic study is presented for the front/back interface states. The proposed model is applied to evaluate the down-scaling of FDSOI technologies in terms of the gate-coupled slope factor. The scaling in the buried oxide layer degrades the front slope factor, which a thinner channel or a reverse body bias can compensate for at the cost of a higher vertical electric field. Compared to the SiO2, the application of high-κ dielectric for the buried oxide layer shows a better stand to the degraded slope factor by the interface states.

Non-contact salinity measurement using a bifurcated fiber bundle sensing

A non-contact salinity sensor using a bifurcated fiber bundle sensing is proposed. The sensor was operated based on intensity modulation due to the variation of displacement between the tip of the probe with the surface of the sample. The light that reflected back into the receiving fiber bundle is analysed and correlation with the salinity of the samples has been performed. This allows the performance of the sensor towards salinity to be quantified based on the front slope, back slope and peak intensity. The proposed configuration has been calibrated and then experimentally validated. The calibration curve can be plotted based on three parameters: peak intensity, front slope and back slope. The peak intensity curve exhibits the highest sensitivity of 1.52×105 a.u./M with the resolution of 4.2×10-2 M. The ubiquitousness of sensor configuration and non-contact measurement make the proposed sensor a viable alternative to standard commercial devices.

Numerical Analysis on the Stability of Sandstone-Covered Mudstone Cutting Slopes Considering Rainfall Infiltration

Landslide caused by rainfall are easily produced when excavating conduct in sandstone-covered mudstone strata. The expansion project of the Heishan Village to Jixi section of Dan-A Highway is used as an example to study the formation and damage mechanism of rainfall-induced landslide in sandstone-covered mudstone cutting slope. Finite element numerical is used to analyze the stability of the slope by using Geo-Studio and ANSYS software for the three different rainfall-influencing factors of rainfall intensity, duration and rainfall form. The study indicates that rainfall time and intensity will decrease the stability of the cutting slope, and that the effect of rainfall on the slope is lagging behind. When rainfall intensity is 80 mm, rainfall duration is 1 d, and stagnation is 5 h, the slope instability is in the critical state. The front slope toe is the first unstable part in the process of slope instability. Rock and artificial construction are important reasons for this phenomenon.

Transitional rock glaciers at sea level in northern Norway

Abstract. Rock glaciers are geomorphological expressions of permafrost. Close to sea level in northernmost Norway, in the subarctic Nordkinn peninsula, we have observed several rock glaciers that appear to be active now or were active in the recent past. Active rock glaciers at this elevation have never before been described in Fennoscandia, and they are outside the climatic limits of present-day permafrost according to models. In this study, we have investigated whether or not these rock glaciers are active under the current climate situation. We made detailed geomorphological maps of three rock glacier areas in Nordkinn and investigated the regional ground dynamics using synthetic aperture radar interferometry (InSAR). One of the rock glaciers, namely the Ivarsfjorden rock glacier, was investigated in more detail by combining observations of vertical and horizontal changes from optical images acquired by airborne and terrestrial sensors and terrestrial laser scans (TLSs). The subsurface of the same rock glacier was investigated using a combination of electrical resistivity tomography (ERT) and refraction seismic tomography (RST). We also measured ground surface temperatures between 2016 and 2020, complemented by investigations using an infrared thermal camera, and a multi-decadal climatic analysis. We mapped the rock glaciers in the innermost parts of Store and Lille Skogfjorden as relict, while the more active ones are in the mouths of both fjords, fed by active talus in the upper slopes. Several of the rock glaciers cross over both the Younger Dryas shoreline (25 m a.s.l.) and the Early to Mid-Holocene shoreline at 13 m a.s.l. Both InSAR and optical remote sensing observations reveal low yearly movement rates (centimetres to millimetres per year). The ERT and RST suggest that there is no longer permafrost and ground ice in the rock glacier, while temperature observations on the front slope indicate freezing conditions also in summer. Based on the in situ temperature measurements and the interpolated regional temperature data, we show that the mean annual air temperature (MAAT) of the region has risen by 2 ∘C since the late 19th century to about 1.5 ∘C in the last decade. MAATs below 0 ∘C 100–150 years ago suggest that new rock glacier lobes may have formed at the end of the Little Ice Age (LIA). These combined results indicate that the Nordkinn rock glaciers are transitioning from active to relict stages. The study shows that transitional rock glaciers are still affected by creep, rock falls, snow avalanches, etc., and are not entirely dynamically dead features. Our contrasting results concerning permafrost presence and rock glacier activity show the importance of a multi-methodological approach when investigating slope processes in the edge zones of permafrost influence.

Late Holocene sediment provenance change in the Red River Delta: A magnetic study

Holocene climate change and human activities can lead to sediment composition variations. In this study, two drilled cores (VN and GA) from the Red River Delta, Vietnam, were subjected to magnetic measurement, as well as particle size, diffuse reflectance spectroscopy (DRS), and geochemical analyses, to infer Holocene sediment provenance changes. Both cores VN and GA cover estuarine, shallow marine, delta front slope, delta front platform, and delta plain facies in ascending order, with the former covering the whole Holocene while the latter covering the late Holocene. In the younger core GA, the clay content has a significant positive correlation with magnetic grain-size indicators (χARM/SIRM and χfd%) and a negative correlation with demagnetization parameters (S-100 mT and S-300 mT), reflecting the enrichment of fine-grained ferrimagnetic minerals and antiferromagnetic minerals in finer sediments. On the contrary, the relationship between the above-mentioned magnetic properties and clay content is not significant in core VN, reflecting the impact of stronger post-depositional diagenesis. In addition, diagenesis in the shallow marine and delta front slope facies of two cores is more pronounced, which is due to the fact of higher input of marine-sourced organic carbon. A magnetic comparison of the upper parts of two cores indicates that there are sediment source changes within the last 2000 years, which is supported by DRS analysis. Sediments in delta front slope and delta front platform of two cores have similar goethite content, but core GA contains higher hematite content indicating a drier condition. Such a sediment source change can be interpreted by variations of monsoon climate and reworking of soil due to human disturbance. Surface soil erosion due to human activities over the last 0.5 ka is supported by the presence of ultra-fine grained magnetite. Our study demonstrates that magnetic properties together with DRS analysis can provide insights into paleoclimate and paleoenvironmental change in deltaic environments.

Experimental Simulation Study of the Dominant Enrichment Area of Terrestrial Organic Matter in the Shallow‐Delta Sedimentary System of the Yacheng Formation in the Qiongdongnan Basin

AbstractShallow‐delta sedimentary systems receive both terrestrial and marine organic matter. As oil and gas exploration activities determine that the source rocks of the deep‐water area of the Qiongdongnan Basin, northern South China Sea, are generally rich in and even dominated by terrestrial organic matter, this has led many researchers to examine the rules governing terrestrial organic matter enrichment in shallow‐delta sea sedimentary systems. However, the deep burial of source rocks in deep‐water areas and the relatively small amount of drilling undertaken have greatly restricted the study of these rules. In this study, the ‘forward modeling’ research method was used to observe and analyze the deposition and preservation of terrestrial organic matter through flume experiments, where the depositional results were carefully depicted and sampled. The total organic carbon content of selected samples was measured and when combined with qualitative observations and quantitative comparison results, the dominant enrichment areas of terrestrial organic matter were identified. The experimental results show that the overbank parts of the delta front, the dune countercurrent surface, the low‐lying parts, the delta front slope area and the shallow‐prodelta sea area are where terrestrial organic matter is predominantly enriched. This provides an important basis and guidance for the prediction of the development areas of marine source rocks with terrestrial input in the deep‐water areas of the Qiongdongnan Basin.

Flash flooding on Mars could be linked to large fault slip events

Studies of Martian fault-related landform morphology have noted an interesting phenomenon associated with large thrusts — isolated channels that run from the crests of these landforms down their slopes. One such example is Ogygis Rupes, an east-verging, 180 km long thrust-fault-related landform located near 55°W, 33°S. Geometric modeling efforts have indicated the fault underlying this landform has experienced approximately 2850 m of slip, and a large anticlinal fold has grown above the fault. We mapped 72 channels on back and front slopes of this massive landform at 1:24,000 scale on 10 mosaiced Context Camera images (6 m/pixel) and one High-Resolution Imaging Experiment image (2.5 m/pixel). The morphology of these channels indicates that they formed through flash flood events that originated near the hinge of the fold. We propose that these flooding events were due to the melting of subsurface ice during fault slip. We apply a thermodynamic model for heat generation along the fault surface during slip events of various magnitudes to estimate the volumes of water produced during each hypothetical event. By comparing these estimates to channel discharge values estimated from channel morphologies, we resolve fault slip magnitudes that could produce the channels. We find that slip events of approximately 28 m produce enough heat to melt the ice associated with channel flow (4.867 × 109 m3). This estimate is based on slip within a 1 m basaltic fault zone, with a friction coefficient of 0.6 where all pore space is occupied by water ice. Results indicate that only mature faults with well-developed, fractured hinges are capable of both (1) melting enough subsurface ice and (2) transporting the water to the surface to result in flooding, explaining why this impressive phenomenon remains a rare but important hazard of which to be aware during planning of the exploration and settlement of Mars.

Empirical estimation of the breaker index using a stereo camera system

To understand the wave-breaking phenomenon that affects coastal structures and sediment transport, various experiments have been conducted using an experimental wave flume equipped with point observation instruments including wave gauges. However, it has been still challenging to precisely measure the wave propagation in the breaking region. In this study, the water surface elevation is observed using stereo cameras, and a modified index for the breaking wave height is proposed. Water surface fields are retrieved spatially and temporally from synchronized stereo images using the wave acquisition stereo system (WASS), and then the breaking wave height, location, and wave front slope angle (WFSA) are analyzed. For the verification of the camera system, a three-dimensional reconstructed map is compared with the wave elevation measured by the wave gauge. The critical WFSA is empirically formulated and used to modify the breaker index. We verify the proposed breaker index formula by applying the index to the spilling breakers with a wide range of relative water depths. The prediction of the breaker index that rapidly decreases under high relative water depth conditions is considerably improved. Using the proposed critical WFSA formula and modified breaker index, the breaking wave heights in coastal areas can be accurately estimated.

Analysis of Gas Flow Dynamics in Thermal Cut Kerf Using a Numerical and Experimental Approach for Nozzle Selection

Consistency in gas flow behavior under various operating conditions is expected for uniform cutting performance in the thermal cutting process. The slope of the cut front in the kerf slot of a sample cutting material varies with the operating condition which affects the gas flow pattern. Therefore, how the nozzle exit diameter and the slope of the cut front effects gas flow behavior has been studied using the Reynolds averaged Navier–Stokes (RANS) based k–ω turbulence model. Convergent–straight-type nozzles with exit diameters φexit of 1.5 mm, 2 mm and 2.5 mm were used to study the flow patterns through the kerf slots of variable cut front slopes. The numerical simulation results were then compared with the results obtained from the Schlieren experiments. In addition, image processing was performed in the Schlieren images for clear visualization and precise comparison of the numerical and experimental data. The results confirm that a nozzle with an exit diameter of 2 mm shows a higher consistency in flow behavior in variable operating conditions.