Actual Terrain Research Articles

Study on power characteristics of wind turbine on the Loess Plateau terrain based on wind tunnel experiment

In order to investigate the impact of the flow field on wind turbine power in northwest China’s Loess Plateau, a wind tunnel experiment was conducted using a self-designed model that simulated the actual terrain. By comparing experiments utilizing an ideal mountain model under varying incoming wind speeds, it was revealed that the Loess Plateau terrain resulted in an increased inflow wind speed for the wind turbine. This higher inflow wind speed led to an approximate 5% increase in output power but also caused about a 6.1% rise in power fluctuations. Through analysis of the power spectrum of the output, it was discovered that turbulence below the decoupling frequency strongly modulates the output power of the wind turbine. This study also provided insights into spatial scale ranges where incoming flow turbulence structures can modulate output power, ranging from approximately 0.3 times to 5 times the diameter of rotor blades.

Design and research on structure of plateau hand-held cutting and sun drying machine

With the development of agricultural modernization, accelerating agricultural mechanization has become an important direction for the development of agriculture in China. However, agricultural mechanization is uneven and insufficient in terms of regions, industries, crop varieties, and production stages. Although there are already a large number of agricultural machinery products on the market, most of them are designed for large-scale crops in northern arid lands, lacking machinery suitable for barley and adaptable to small plots and sloping farmlands in the Qinghai-Tibet Plateau region. The development of a barley harvester adapted to plateau mountainous areas contributes to the development of special agricultural machinery in China, improves the uneven development of agricultural mechanization, and promotes agricultural development in plateau mountainous areas. This paper conducts research on the actual terrain of the Qinghai-Tibet Plateau, barley planting conditions, and harvester operational conditions. Based on the production needs of barley agriculture, the design is optimized and improved. Following the principle of overall coordination, the overall structural parameters of the harvester suitable for the operational requirements of plateau mountainous areas are determined. The structural design of key components such as wheelbase, axle spacing, ground clearance, harvesting mechanical arm, and harvesting mechanism is detailed. Additionally, SolidWorks software is used for three-dimensional modeling of the barley harvester. CAE technology is employed to analyze the static and dynamic performance of critical chassis components, validate theoretical calculations, and confirm final structural parameters. Furthermore, a dynamics characteristic model is established based on the optimized parameters to theoretically analyze the stability of the entire machine and verify whether the designed plateau barley harvester meets field operation requirements. Finally, Bluetooth communication technology is utilized to autonomously design control hardware and software, achieving intelligent control of the machinery.

Research on deep-sea terrain refinement methods based on satellite remote sensing data

Bathymetric data is crucial for navigation safety and various applications. However, only a small portion of the seafloor has been systematically mapped through direct measurement. The remaining bathymetry is estimated from satellite altimeter data, providing only an approximate representation of the seafloor's shape. To address this issue, the convolutional neural network (CNN) is introduced for the analysis of seabed topography. To the best of our knowledge, this marks the first attempt to incorporate the CNN into the definitive map of the world ocean floor. By employing skip connections based on residual learning, we construct a deeper CNN layer that effectively reduces training complexity. The deeper convolutional neural network layer is used to create a more complex nonlinear mapping model, which is then employed to downscale low-resolution seabed topographic data in order to obtain high-precision seabed topographic information. This process enhances the representation of seabed topographic data to reflect the actual terrain more accurately. The results are compared with those obtained using the bicubic difference method. Conducting tests near the Gulf of Thailand, where Malaysia Airlines Flight MH370 was lost, the results demonstrate that the method proposed in this paper achieves higher accuracy in processing the downscaling of seabed topographic data.

Effects of Terrain on the Landing of Locusta migratoria migratoria (Orthoptera: Acrididae) at the China–Kazakhstan Border1

Abstract We conducted a case study on the severe damage caused by the transboundary migration of Locusta migratoria (L.) (Orthoptera: Acrididae) in the Tacheng Prefecture and the Altay Prefecture at the China–Kazakhstan border by examining the effects of terrain on their landing behaviors. Based on the time and location of the locusts’ mass landings, we used mesoscale weather research and forecasting models to test the sensitivity (horizontal wind, vertical wind, temperature, and rainfall) of the terrain and simulate the effects of different terrain heights (terrain leveling, half terrain height, and actual terrain height) on landing. The results showed that changes in the regional terrain of the Tacheng and Altay prefectures did not enhance the vertical airflow over the landing area. With an elevation of the terrain, the precipitation intensity in the landing area of locusts also did not increase. We did detect a direct impact of wind direction and changes in temperature in the regional terrain on the landing process of L. m. migratoria. With an increase in terrain altitude, the wind direction over the landing area changed and the temperature decreased, resulting in large-scale forced landing. The results of this study have important value in predicting and forecasting the arrival of migratory locusts.

Composite Electromagnetic Scattering Characteristics of Actual Terrain and Moving Rockets

This research involved studying the characteristics of composite electromagnetic scattering from a rocket moving above actual terrain using the finite-difference time-domain method. The angular distribution curve of the composite scattering coefficient was obtained, and the influences of factors such as the angle of incidence, the frequency of the incident electromagnetic wave, the content of moisture in soil, the dielectric constant of the rocket-shell material, the height of the rocket, and the undulation of the terrain on the composite scattering coefficient were investigated. Results show that the composite scattering coefficient oscillates with the scattering angle and increases in the direction of mirror reflection. It also decreases with increasing angle of incidence, frequency of the incident wave, and altitude of the rocket, while it increases with increasing soil moisture and dielectric constant of the rocket-shell materials. Although the influence of different terrain undulations on the composite scattering coefficient is noticeable, it follows no fixed pattern.

Variation in Debris-Flow-Prone Areas with Ecosystem Stability: A Case Study of the Qipan Catchment in the Wenchuan Earthquake Region

The spatial distribution of vegetation in a basin has a far-reaching influence on the potential for sediment separation and transport capacity. However, many landslides induced by strong earthquakes have greatly changed the existing pattern, which further increases the probability of debris flow in a basin during heavy rainfall and has a significant impact on the stability of the basin. Thus, this study selected the debris flow basin in the Qipan catchment of the Wenchuan earthquake area as the research object. Multisource and high-precision remote sensing images were used to analyze the land use changes in the basin, and the index of connectivity (IC) was introduced to analyze the evolution of sediment transport capacity. An ecosystem stability assessment method suitable for post-earthquake debris flow basins was proposed. Through quantitative assessment of the ecosystem stability of the basin after the Wenchuan earthquake in 2008 and the two debris flow events after the earthquake, the dynamic relationship between the debris-flow-prone area and the ecosystem stability of the basin was revealed. The results showed that the stability of the ecosystem in the Qipan catchment increased annually, indicating a stable and substable state. The spatial distribution characteristics were lower in the north and south and greater in the middle. By comparing the evaluation results with the actual terrain change trend, the accuracy and feasibility of the evaluation method are verified. The results of this study provide a scientific basis for the formulation of regional disaster prevention strategies and help to accelerate the improvement of regional stability in debris-flow-prone areas.

Examining trade routes through the Thai–Malay Peninsula: A simulation analysis

An important area for understanding human movement and trade routes during the Early Historic Period in Southeast Asia is the Thai–Malay Peninsula where external records date back 2300 years. Early east–west trade could be routed around the peninsula or sailing time could be reduced by taking terrestrial shortcuts across the peninsula. However, spatial research, particularly on transpeninsula routes, is insufficient to supplement the gaps between written historical records and excavated archaeological sites. This study aimed to simulate transpeninsula routes across the entire Thai–Malay Peninsula using a digital elevation model (DEM) to eliminate human biases when exploring the actual terrain. The simulation results reveal some intriguing characteristics of potential routes that can be used to divide the Thai–Malay Peninsula into five zones. This zonation is associated with external historical records and archaeological evidence before the twelfth century AD to assess the efficacy of different transpeninsula routes. These data are also utilized to propose potential areas of undiscovered archaeological sites within the Thai–Malay Peninsula.

Multi-beam line observation optimization strategy based on random variable unitary iterative model

Multibeam system has many advantages such as large measurement range, fast speed, high accuracy, etc., which can be applied in many fields such as marine topographic survey. In this paper, the relationship between coverage width and other variables is obtained by analyzing the geometric relationship between each parameter, and a multibeam sounding model based on geometric relationship is established. And based on the intelligent optimization algorithm, an iterative optimization model with random variable singularization is designed independently. And the actual terrain data were visualized and simplified into various parameters in line with the model. With the help of the definition of the coverage rate, the relationship between the coverage width and other variables, and the one-to-one correspondence between the translation distance of the slope and the coverage rate, the complex measurement problem can be transformed into a simple linear programming problem, and the relationship model between the coverage rate and other variables is established. In the end, the model can be used to derive the optimal wiring scheme to realize high-precision and full-coverage sweeping of the seabed terrain in the given sea area without omission, provided that the ship speed, beam opening angle and other factors are reasonable.

Snowfall deposition in mountainous terrain: a statistical downscaling scheme from high-resolution model data on simulated topographies

One of the primary causes of non-uniform snowfall deposition on the ground in mountainous regions is the preferential deposition of snow, which results from the interaction of near-surface winds with topography and snow particles. However, producing high-resolution snowfall deposition patterns can be computationally expensive due to the need to run full atmospheric models. To address this, we developed two statistical downscaling schemes that can efficiently downscale near-surface, low-resolution snowfall data to fine-scale snow deposition accounting for the effect of preferential deposition in mountainous regions. Our approach relies on a comprehensive, model database generated using 3D wind fields from an atmospheric model and a preferential deposition model on several thousand simulated topographies covering a broad range in terrain characteristics. Both snowfall downscaling schemes rely on fine-scale topographic scaling parameters and low-resolution wind speed as input. While one scheme, referred to as the “wind scheme”, further necessitates fine-scale vertical wind components, a second scheme, referred to as the “aspect scheme”, does not require fine-scale temporal input. We achieve this by additionally downscaling near-surface vertical wind speed solely using topographic scaling parameters and low-resolution wind direction. We assess the performance of our downscaling schemes using an independent subset of the model database on simulated topographies, model data on actual terrain, and spatially measured new snow depth obtained through a photogrammetric drone survey following a snowfall event on previously snow-free ground. While the assessments show that our downscaling schemes perform well (relative errors ≤ ±3% with modeled and ≤ ±6% with measured snowfall deposition), they also demonstrate comparable results to benchmark downscaling models. However, our schemes notably outperform the benchmark models in representing fine-scale patterns. Our downscaling schemes possess several key features, including high computational efficiency, versatility enabled by the comprehensive model database, and independence from fine-scale temporal input data (aspect scheme), indicating their potential for widespread applicability. Therefore, our downscaling schemes for near-surface snowfall and vertical wind speed can be beneficial for various applications at fine grid resolutions such as in atmospheric and climate sciences, snow hydrology, glaciology, remote sensing, and avalanche sciences.

Experimental investigation on influence of terrain complexity for wind pressure of low-rise building

This study conducted extensive wind tunnel tests to evaluate the impact of terrain complexity on wind pressure across low-rise buildings. A series of wind tunnel tests was performed using 50 actual terrain morphologies in the US. The findings were compared with results obtained from testing on homogeneous terrain to discern variations in pressure coefficients. A notable increase in turbulence intensity was observed in complex heterogeneous terrains, even with similar effective roughness lengths. The heightened turbulence property was a crucial factor in explaining changes in Cp,mean. The magnitude of Cp,mean demonstrated a continuous rise in the windward wall and roof 1 regions with increasing turbulence intensity. This correlation held true even for Iu,eave values surpassing 0.3. In contrast, while Cp,RMS exhibited a tendency to increase with rising Iu,eave, it did not exhibit the same continuous increase phenomenon. Consequently, no significant disparity in magnitude was noted between homogeneous and heterogeneous terrains in this regard. These findings underscore the importance of accounting for terrain complexity in wind load assessments, particularly in scenarios of heightened terrain diversity, to mitigate potential errors in wind load evaluations.

Experimental Study of Seamless Switch Between GNSS- and LiDAR-Based Self-Localization

A self-localization method that can seamlessly switch positions and attitudes estimated using normal distributions transform (NDT) scan matching and a real-time kinematic global navigation satellite system (GNSS) is successfully developed. One of the issues encountered in this method is the sharing of global coordinates among the different estimation methods. Therefore, the three-dimensional environmental maps utilized in the NDT scan matching are created based on the planar Cartesian coordinate system used in the GNSS to obtain accurate information regarding the location, shape, and size of the actual terrain and geographic features. Consequently, seamlessly switching between different methods enables mobile robots to stably obtain accurate estimated positions and attitudes. An autonomous driving experiment is conducted using this self-localization method in the Tsukuba Challenge 2022, and the mobile robot completed a designated course involving more than 2 km in an urban area.

End-effector path tracking of a 14 DOF Rover Manipulator System in CG-Space framework

AbstractIn order to resolve redundancy and path planning of a high DOF mobile manipulator using conventional approaches like Jacobian and a pseudoinverse method, researchers face the limitation of computational load and delay in response. If such kind of mobile manipulator is traversing the rough terrain, then conventional methods become too costly to implement due to the handling of redundant joints, obstacles, and wheel-terrain interaction. A few optimization-based redundancy resolution approaches try incorporating wheel-terrain interaction but fail in real-time response. This paper describes a 14 DOF Rover Manipulator System’s end-effector path-tracking approach using CG-Space framework to incorporate wheel-terrain interaction. CG-Space means the center of gravity (CG) locus of the Rover. The Rover’s CG is calculated while traversing over 3D terrain using a multivariable optimization method and a 3D point cloud image of the actual terrain and stored as CG-Space over the given terrain. First of all, we decide which part of the system moves to track the path, that is, arm or Rover, depending upon the manipulator’s work volume and manipulability measure restrictions. The next task is to obtain the Rover pose according to the end-effector path using a simple arm’s inverse kinematic solution between the CG-Space and end-effector task space without resolving redundancy. Meanwhile, obstacles and non-traversable regions are avoided in CG-Space. On diverse 3D terrains, simulation and experimental results support the suggested CG-Space framework for end-effector tracking.

Research on the Bias Sampling RRT Algorithm for Supermarket Chain Distribution Routes under the O2O Model

The purpose of this article is to propose the Bias Sampling RRT algorithm and use it as an optimization algorithm for supermarket chain distribution routes under the O2O model. As a retail store in the transformation and upgrading of chain stores, the actual terrain factors in distribution directly affect the timely delivery of goods from online to offline. The Bias Sampling RRT algorithm, as a path search method for time window vehicle routing problems, can find the optimal path that meets time window constraints. The applicability and effectiveness of the Bias Sampling RRT algorithm have been demonstrated through map simulation calculations. The simulation results show that compared with the RRT method, the Bias Sampling RRT algorithm has a shorter distribution path and shorter distribution time. This method is very suitable for the distribution activities of chain supermarkets or single store retail enterprises in the complex transformation and upgrading of actual terrain.

Structural and Environmental Safety Studies of the Holy Mosque Area Using CFD

A three-dimensional (3D) CFD model was developed, covering a square area of 3.64 km2 and comprising the Holy Mosque near its center, the actual terrain, and the main surrounding buildings. The gust wind effects on the existing cranes and the collapsed tower crane in 2015, the comfort of the pedestrians, and the air quality were studied for the first time in this area. The air quality was related to calm speed, accelerating the spreading of infectious diseases. The wind comfort levels were achieved in all selected locations. The wind speeds are generally low in the area. However, gusting wind currents appeared from limited directions, causing increments in wind speeds up to 30% and causing the tower crane to collapse. Therefore, finalizing work on some cranes is recommended soon, lowering the crane boom and stopping working on windy days or changing their places. The air quality in some sites may be relatively poor, such as at the lower terraces level. New tall buildings surrounding the mosque from the north and the east are not recommended unless studying their impacts on the air quality. Pruning north and east mounts can remarkably improve natural ventilation. Large-scale fans are another solution after a detailed simulation study.

Analytical Comparison of Path Loss Models for Radio Wave Propagation over Yenagoa–Southern Nigeria

Using propagation models helps with communication system planning and maximizes the use of the radio spectrum, a limited natural resource. Here is a comparative analysis between some propagation models and actual measurements from Yenagoa, Southern Nigeria. Electric field strength measurements made during drive tests for two television transmitters operating at 210.25 MHz and 577.10 MHz make up the experimental data. Analytical comparisons were made between verified predictions for the free space, Okumura, and Hata models and measured data. The results demonstrate that these empirical models fail to take into account Yenagoa's actual terrain profile for television broadcast. The Okumura model is the best fit, with ideal values for root mean square error (RMSE) of 34.9136 and 33.2841 and average relative error of 0.13212 and 0.4327 for 210.25 MHz and 577.10 MHz, respectively. However, if the Okumura model is tailored for Yenagoa to improve electric field strength prediction and coverage estimation, better results can be attained.

Diffusion simulation and risk assessment model establishment of chlorine gas leakage based on terrain conditions

This study researches the impact of terrain factors on chlorine gas diffusion processes based on SLAB model. Simulating the law of wind speed changing with altitude by calculating the real-time speed with vertical height combing actual terrain data, and integrating the influence of terrain on wind speed by using Reynolds Average Navier-Stokes (RANS) algorithm, K-turbulence model, and standard wall functions, then plotting the gas diffusion range in the map with terrain data according to the Gaussian-Cruger projection algorithm and dividing the hazardous areas according to the public exposure guidelines (PEG). The accidental chlorine gas releases near Lishan Mountain, Xi'an City, were simulated by the improved SLAB model. The results show that there are obvious differences analyzing contrastively the endpoint distance and area of chlorine gas dispersion under real terrain condition and ideal condition at different times; it can be found that the endpoint distance of the real terrain conditions is 1.34km shorter than that of the ideal conditions at 300s with terrain factors, and also the thermal area is 3,768,026m2 less than that of the ideal conditions. In addition, it can predict the specific number of casualties within different levels of harm at 2min after chlorine gas dispersion, and casualties are constantly changing over time. The fusion of terrain factors can be used to optimize the SLAB model, which is expected to provide an important reference for effective rescue.

Hazard identification and risk assessment for occupational safety and health in the limestone quarries transportation

In quarries for building material, the primary transportation mode is by truck due to its high mobility that is suitable for the actual terrain conditions of the mine. The characteristic of transportation work in these mines is the large amount of cargo transportation, steep slopes, small turning radius, and therefore always potential hazards and risks for workers at the mine. The article presents a method for evaluating the points to identify and assess the level of occupational safety and health risks in transportation activities in quarries for building material, based on which control solutions are proposed to ensure safety and occupational health during the production and business process of construction material mines. From identifying and evaluating the level of risks, they are quantified into risk levels to assess the potential loss of occupational safety at each specific stage of the transportation process in the mine. This is a quantitative method that allows for the easy evaluation of occupational safety and health risk levels through quantifiable values obtained by expert scoring and surveys of worker opinions at the production site. This evaluation is based on separate assessments of factors such as estimating the consequences of injury to workers, the frequency of occupational accidents, and the ability to recognize occupational hazards. Through this assessment, a classification table is proposed for workers to understand and implement occupational safety and health procedures correctly, avoiding occupational accidents and unnecessary occupational diseases.

실제 지형 환경과 지구 곡률이 반영된 재밍 유효거리 분석을 위한 M&S 기법

Jammers are commonly employed in electronic warfare (EW) environments. A system that can respond according to the jamming signals emitted by jammers can be developed by predicting the affected radar detection range and burn through range. In this paper, we propose an M&S technique for calculating the received power by considering the actual terrain information and the curvature of the Earth, and analyze the burn through range with the specifications of the radar and jammer. The proposed M&S technique was applied by using the specifications of the experimented actual radar, and the burn through range was analyzed for targets with various radar cross sections. It was confirmed that the burn through range from the radar decreased as the radar cross section of the target decreased, and the effective isotropic radiated power of the jammer decreased.

Orographic Controls over Convection in an Inter-Andean Valley in Northern South America

Abstract Convective processes are critical in the northernmost section of the Andes, where highly complex orography combines with tropical dynamics to produce intense precipitating systems. Data from satellite and ground radar have shown that Colombia’s central Magdalena valley has a marked precipitation diurnal cycle, with high rainfall rates produced by deep convective events that intensify on the foothills of the surrounding valley. This study aims to contribute to the understanding of the orographic controls imposed on the convective activity observed in this important tropical valley. The atmospheric environments associated with convective events are assessed using WRF high-resolution simulations for a two-week period that includes intense rainfall events and marked dry spells. In addition, a simulation with modified orography is evaluated to analyze further the effect of topography in controlling the observed convective systems. The results suggest that northward and southward wind regimes channeled by the valley’s topography and cross-valley flow result in a robust nocturnal convergence zone, which is associated with the strong diurnal cycle and the valley configuration. Furthermore, northerly low-level flow is an important source of moisture for convection in the valley. Additionally, results show midlevel tropospheric heating enhancement during days with more rainfall produced by convective systems in the western slope of the valley. The modified topography simulation suggests that circulation and precipitation in the valley are strongly dependent on the actual terrain features.

Impact of inundation range of overtopping dam break of tailings pond under actual terrain conditions.

Tailing ponds are a major hazard source with the risk of dam breaks. To predict the impact of tailings pond dam breaks more accurately, one needs to quantitatively understand the dam-breaking process of the tailings reservoir and its downstream impact. This study is based on an old tailings pond that is about to be put out of service and the proposed new tailings pond next to it. Study the inundation range of the new and old tailing ponds with simultaneous overtopping dam breaks under actual terrain conditions. First, fine-grained tailings and expanded perlite were selected as the model sand materials, and the appropriate model sand ratio was determined through laboratory tests. Second, the two tailings ponds were tested (at a scale of 1:200), for flood overtopping and simultaneous dam breaks. The dam break, flow, section morphology evolution, submerged elevation, and range were analyzed. Finally, a numerical model was developed using MIKE 21 to simulate the simultaneous overtopping and collapse of the new and old tailings ponds, and the impact of rainfall intensity on the inundation range of the simultaneous overtopping of the dam was analyzed. The research results will guide disaster prevention and mitigation in tailings reservoirs.