Laboratory Model Tests on Flow Erosion Failure Mechanism of a Slope Consisting of Anqing Group Clay Gravel Layer

The Anqing group clay gravel layer is a special geological body composed of gravel and clay. In excavation projects, involving this soil, such a gravel layer, is prone to slope collapse and instability under the influence of rainfall. To clearly understand the failure mechanism and influencing factors of clay gravel slopes, an indoor artificial rainfall erosion model testing was carried out to analyse the effect of various slope ratios, gravel contents, and rainfall intensities. The slope erosion damage form, runoff rate, infiltration rate, scoured material, and slope stability of the clay gravel slope were studied. The test results show that sloping surfaces of the gentle slope were mainly damaged by erosion, and the degree of damage gradually increased from the top to the bottom of the sloping surface; however, the stability of the surface was good. In the case of the sloping surface layer of the steep slope, large-scale landslides occurred, and the stability of the surface was poor. When the gravel content was small, the surface failure was manifested as a gully failure. When the gravel content was large, it was manifested as a “layer-by-layer sliding” failure. The degree of influence of different conditions on the stable runoff rate was as follows: rainfall intensity>slope ratio>gravel content. The degree of influence of the parameters on the stable infiltration rate was as follows: slope ratio>rainfall intensity>gravel content. On gentle slopes, the total mass of the scoured material was inversely proportional to the gravel content and directly proportional to the rainfall intensity; on a steep slope, the total mass of the scoured material increased with an increase in the rainfall intensity and gravel content. Moreover, the slope ratio was the key influencing factor to decide whether there was gravel in the scoured material.

Deformation Behavior of Mining beneath Flat and Sloping Terrains in Mountainous Areas

Slope structures and surface terrains are two significant factors affecting the deformation behavior of mining slopes in mountainous areas. This research is aimed at investigating the deformation characteristics of a mining slope wielding Particle Flow Code (PFC), with 9 different mining configurations (i.e., horizontal distance from extracted panel center to slope shoulder, D = −200 m, −150 m, −100 m, −50 m, 0 m, 50 m, 100 m, 150 m, and 200 m). A representative slope in Faer Town, Liupanshui City, Guizhou Province, China, was selected, which was characterized by soft and hard interbedded rock strata. The results indicated that the overlying rock mass tended to move towards the sloping surface with mining beneath sloping terrain, which brought an asymmetrical subsidence funnel, and formed a wider relative disturbance range on the slope surface. With the vertical subsidence increasing additionally, the stability of the overall slope deteriorated. A safe mining range should be proposed based on evaluating the time-dependent deformation behavior at the slope shoulder and the overall slope stability.

Penentuan Sudut Kemiringan Optimum Berdasarkan Energi Keluaran Panel Surya

Angle tilt is an important factor that affects the amount of solar radiation received on the surface of solar panels. Fixed-mounted solar panels cannot receive the maximum amount of solar radiation. How to get the maximum solar radiation by positioning the surface of the solar panel at a certain slope to be directly facing the sun. This study aims at determining the optimum slope angle of solar panels in the city of Meulaboh (4,152 LU, 96,131 BT). The method of calculating the total value of solar radiation on a sloping surface simulated with Pvsyst Software is used to determine the annual optimum tilt angle. NASA SSE solar radiation data from 1983 – 2005 were used to support simulations in this study. The results showed that the tilt angle that can produce the maximum output energy in the city of Meulaboh (4,152 LU, 96,131 BT, Johan Pahlawan) is at an angle of 5° with the orientation directly facing south.

Influence of incident angle and laser footprint on precision and level of detail in terrestrial laser scanner measurements

Terrestrial laser scanners (TLS) are used for a variety of applications, e.g., surveying, forestry, cultural heritage preservation, mining, topographic mapping, urban planning, forensics etc. This technology has made a huge shift in 3D spatial data collection due to much faster speed compared to other techniques. In the absence of guiding principles for positioning TLS relative to an object, surveyors collect data at maximum arrangements of scanning geometry elements due to fear of incomplete data of TLS. In 3D spatial data acquisition, positional accuracy and Level of Detail (LOD) are major considerations and are dependent on laser incident angle, footprint size, range and resolution. Mathematical models have been developed relating range, incident angle and laser footprint size for different surface configurations. These models can be used to position TLS to collect data at required positional accuracy and LOD. Models have been verified by deriving one model from other surface models by changing parameters. Effects of incident angle and footprint size have been studied mathematically and experimentally on a natural sloping surface. From the results, surveyors can plan the positioning of the scanner so that data is collected at the required accuracy and LOD.

Brachistochrone on a velodrome

The Brachistochrone problem, which describes the curve that carries a particle under gravity in a vertical plane from one height to another in the shortest time, is one of the most famous studies in classical physics. There is a similar problem in track cycling, where a cyclist aims to find the trajectory on the curved sloping surface of a velodrome that results in the minimum lap time. In this paper, we extend the classical Brachistochrone problem to find the optimum cycling trajectory in a velodrome, treating the cyclist as an active particle. Starting with two canonical cases of cycling on a sloping plane and a cone, where analytical solutions are found, we then solve the problem numerically on the reconstructed surface of the velodrome in Montigny le Bretonneux, France. Finally, we discuss the parameters of the problem and the effects of fatigue.

A Comparison of Surface Slopes Extracted from ICESat Waveform Data and High Resolution DEM

Surface slope is an important topographic variable, accurate surface slope can support many research appliacations. Large footprint full waveform data has been used to estimate the surface slope and performes well. In this paper, surface slope within laser footprint is calculated using the Ice, Cloud, and land Elevation Satellite (ICESat) Geoscience Laser Altimeter System (GLAS) full waveform data and a high resolution Digital Elevation Model (REMA, the Reference Elevation Model of Antarctica). A comparison is done between two extracted surface slopes, the results show that the slopes extracted from full waveform data are close to slopes extracted from DEM, and the width of waveform can be used to extract surface slope in moderately sloping surface.

Asymmetric Craters on the Dwarf Planet Ceres—Results of Second Extended Mission Data Analysis

After almost three years of successful operation on Ceres, the Dawn spacecraft entered its last orbits around the dwarf planet and obtained a set of high-resolution images of 3 to 5 m/pixel. These images reveal a variety of morphologic features, including a set of asymmetric crater morphologies as observed earlier in the mission on the asteroid Vesta. We identified 269 craters, which are located between 60° N to 60° S latitude and 197° E to 265° E longitude, and investigated their morphological characteristics using a digital terrain model (DTM). These craters range in diameter from 0.30 to 4.2 km, and exhibit a sharp crater rim on the uphill side and a smooth one on the downhill side. We found that all asymmetric craters are formed on a sloping surface with the majority appearing at slope angles between 5 and 20 degrees. This implies that, as observed on Vesta, the topography is the main cause for these asymmetries.