Search Results (1,442)

Understanding the factors influencing individual tree mortality is essential for sustainable forest management, particularly for Prince Rupprech’s larch (Larix gmelinii var. Principis-rupprechtii) in North China’s natural forests. This study focused on 20 sample plots (20 × 20 m each) established in Shanxi Province, North China. This study compared three individual tree mortality models—Generalized Linear Model (GLM), Linear Discriminant Analysis (LDA), and Bayesian Generalized Linear Model (Bayesian GLM)—finding that both GLM and Bayesian GLM achieved approximately 0.87 validation accuracy on the test dataset. Due to its simplicity, GLM was selected as the final model. Building on the GLM model, six binning methods were applied to categorize diameter at breast height (DBH): equal frequency binning, equal width binning, cluster-based binning, quantile binning, Chi-square binning, and decision tree binning. Among these, the decision tree binning method achieved the highest performance, with an accuracy of 90.12% and an F1 score of 90.06%, indicating its effectiveness in capturing size-dependent mortality patterns. This approach provides valuable insights into factors affecting mortality and offers practical guidance for managing Larix gmelinii var. Principis-rupprechtii forests in temperate regions. Full article

The study of energy savings in ventilation systems within buildings is crucial. Impinging jet ventilation (IJV) systems have garnered significant interest from researchers. The identification of the appropriate location for the IJV reveals a gap in the existing literature. This research was conducted to address the existing gap by examining the impact of IJV location on energy savings and thermal comfort. A comprehensive three-dimensional CFD model is examined to accurately simulate the real environment of an office room (3 × 3 × 2.9 m³) during cooling mode, without the application of symmetrical plans. Four locations have been selected: two at the corners and two along the midwalls, designated for fixed-person positions. The return vent height is analyzed utilizing seven measurements: 2.9, 2.6, 2.3, 1.7, 1.1, 0.8, and 0.5 m. The RNG k–ε turbulence model is implemented alongside enhanced wall treatment. The findings indicated that the optimal range for the return vent height is between 1.7 and 0.8 m. It is advisable to utilize the IJV midwall 1 location, positioned behind the seated individual and away from the exterior hot wall. It is characterized by low vortex formation in the local working zone that contributes to a more comfortable sensation while providing recognized energy-saving potential. Full article

The visual morphology of trees significantly impacts urban green micro-landscape aesthetics. Proximity to tall buildings affects tree form due to competition for space and light. The study investigates the impact of tall buildings on six visually morphological traits of eight common ornamental species in urban micro-landscapes in Beijing, with the distance and direction between trees and buildings as variables. It found that as trees grow closer to buildings, most angiosperms show increased crown asymmetry degree and crown loss, and reduced crown round degree and crown stretch degree (i.e., Sophora japonica L. and Acer truncatum Bunge saw a 52.26% and 47.62% increase in crown asymmetry degree, and a 20.35% and 21.59% decrease in crown round degree, respectively). However, the pattern of crown morphological changes in gymnosperms is poor (the closer the distance, the lower the height-to-diameter ratio of Pinus tabuliformis Carr., while the height-to-diameter ratio of Juniperus chinensis Roxb. significantly increases). In terms of orientation, gymnosperms on the west side of buildings have a greater crown asymmetry degree. It suggests that planting positions relative to buildings affect tree morphology. Recommendations include planting J. chinensis closer to buildings but keeping angiosperms like Fraxinus velutina Torr., S. japonica, and A. truncatum more than 3 m away to ensure healthy crown development. Full article

Digital elevation models (DEM) are widely used in many hydrologic applications, providing key information about the topography, which is a major driver of water flow in a landscape. Several open access DEMs with near-global coverage are currently available, however, they represent the elevation of the earth’s surface including all its elements, such as vegetation cover and buildings. These features introduce a positive elevation bias that can skew the water flow paths, impacting the extraction of hydrological features and the accuracy of hydrodynamic models. Many attempts have been made to reduce the effects of this bias over the years, leading to the generation of improved datasets based on the original global DEMs, such as MERIT DEM and, more recently, FABDEM. However, even after these corrections, the remaining bias still affects flow path delineation in a significant way. Aiming to improve on this aspect, a new vegetation bias correction method is proposed in this work. The method consists of subtracting from the Copernicus DEM elevations their respective forest height but adjusted by correction factors to compensate for the partial penetration of the SAR pulses into the vegetation cover during the Copernicus DEM acquisition process. These factors were calculated by a new approach where the slope around the pixels at the borders of each vegetation patch were analyzed. The forest height was obtained from a global dataset developed for the year 2019. Moreover, to avoid temporal vegetation cover mismatch between the DEM and the forest height dataset, we introduced a process where the latter is automatically adjusted to best match the Copernicus acquisition year. The correction method was applied for regions with different forest cover percentages and topographic characteristics, and the result was compared to the original Copernicus DEM and FABDEM, which was used as a benchmark for vegetation bias correction. The comparison method was hydrology-based, using drainage networks obtained from topographic maps as reference. The new corrected DEM showed significant improvements over both the Copernicus DEM and FABDEM in all tested scenarios. Moreover, a qualitative comparison of these DEMs was also performed through exhaustive visual analysis, corroborating these findings. These results suggest that the use of this new vegetation bias correction method has the potential to improve DEM-based hydrological applications worldwide. Full article

Apart from headwind changes, crosswind changes may be hazardous to aircraft operation. This paper presents two cases of recently observed crosswind changes from the range height indicator scans of ground-based remote sensing meteorological equipment, namely an X-band microwave radar and a short-range LIDAR. Both instruments have a range resolution down to around 30 m, allowing the study of fine-scale details of the vertical profiles of cross-mountain airflow at the Hong Kong International Airport. Rapidly evolving winds have been observed by the equipment in tropical cyclone situations, revealing high levels of turbulence and vertically propagating waves. The eddy dissipation rate derived from radar spectrum width indicated severe turbulence, with values exceeding 0.5 m^2/3 s⁻¹. In order to study the feasibility of predicting such disturbed airflow, a mesoscale meteorological model and a computational fluid dynamics model with high spatial resolution are used in this paper. It is found that the mesoscale meteorological model alone is sufficient to capture some rapidly evolving airflow features, including the turbulence level, the waves, and the rapidly changing wind speeds. However, the presence of reverse flow could only be reproduced with the use of a building-resolving computational fluid dynamics model. This paper aims at providing a reference for airports to consider the feasibility of performing high-resolution numerical simulations of rapidly evolving airflow to alert the pilots in advance for airports in complex terrains and the setup of buildings. Full article

Project cost forecasting is a complex and critical process, and it is of paramount importance for the successful implementation of engineering projects. Accurately forecasting project costs can help project managers and relevant decision-makers make informed decisions, thereby avoiding unnecessary cost overruns and time delays. Furthermore, accurately forecasting project costs can make important contributions to better controlling engineering costs, optimizing resource allocation, and reducing project risks. To establish a high-precision cost forecasting model for construction projects in Guangdong Province, based on case data of construction projects in Guangdong Province, this paper first uses the Analytic Hierarchy Process (AHP) to obtain the characteristic parameters that affect project costs. Then, a neural network training and testing dataset is constructed, and a genetic algorithm (GA) is used to optimize the initial weights and biases of the neural network. The GA-BP neural network is used to establish a cost forecasting model for construction projects in Guangdong Province. Finally, by using parameter sensitivity analysis theory, the importance of the characteristic values that affect the project cost is ranked, and the optimal direction for controlling the project cost is obtained. The results showed: (1) The determination coefficient between the forecasting and actual values of the project cost forecasting model based on the BP neural network testing set is 0.87. After GA optimization, the determination coefficient between the forecasting and actual values of the GA-BP neural network testing set is 0.94. The accuracy of the intelligent forecast model for construction project cost in Guangdong Province has been significantly improved after optimization through GA. (2) Based on sensitivity analysis of neural network parameters, the most significant factor affecting the cost of construction projects in Guangdong Province is the number of above-ground floors, followed by the main structure type, foundation structure, above-ground building area, total building area, underground building area, fortification intensity, and building height. The results of parameter sensitivity analysis indicate the direction for cost control in construction projects. The research results of this paper provide theoretical guidance for cost control in construction projects. Full article

Evaporative cooling systems have emerged as low-energy consumption alternatives to traditional vapor compression systems for building air conditioning. This study explored the feasibility of utilizing polymeric foamed materials produced through additive manufacturing as wetting materials in evaporative cooling systems. Specifically, two different commercial polylactic acid filaments, each containing a percentage of a chemical blowing agent, were studied. Experiments were designed to evaluate the influence of critical process parameters (line width, flow rate, speed, and layer height) on the performance of the resulting foamed materials in terms of evaporative cooling by conducting water absorption, capillarity, porosity, and wettability tests. Considering that high water absorption, capillarity, and porosity, coupled with an intermediate contact angle, are advantageous for evaporative cooling effectiveness, a low flow rate was found to be the most important parameter to improve these properties’ values. The results showed that the appropriate combination of polymer and process parameters allowed the production of foamed polymer-based materials processed by additive manufacturing technology with optimal performance. Full article

The rise of high-rise vertical farms in cities is helping to mitigate urban constraints on crop production, including land, transportation, and yield requirements. However, separate issues arise regarding energy consumption. The utilisation of wind energy resources in high-rise vertical farms is therefore on the agenda. In this study, we investigate the aerodynamic performance of an ellipsoidal tall building with large openings to determine, on the one hand, the threshold income wind that could impact human comfort, and on the other, the turbulence intensity at specific locations on the roof and façade where micro-wind turbines could operate. To this end, we calculate the wind pressure coefficient and turbulence intensity of two scale models tested within a wind tunnel facility and compare the results with a separate CFD simulation completed in the past. The results confirm that the wind turbines installed on the building façade at a height of at least z/h = 0.725 can operate properly when the inlet wind speed is greater than 7 m/s. Meanwhile, the wind regime on the roof is more stable, which could yield higher energy harvesting via wind turbines. Furthermore, we observe that the overall aerodynamic performance of the models tested best under wind flowing at angles of 45° and 60° with respect to their centreline, whereas the turbulence at the wind envelope compares to that of the free wind flow at roof height. Full article

Rapid urbanization has intensified public housing development and building density, posing significant challenges to residents’ well-being and urban sustainability. With the population of the Greater Bay Area on the rise, enhancing the spatial quality of public housing is now essential. The study proposed a quantitative framework to evaluate the relationship between the residential design elements and perceived density in high-density public housing neighborhoods. It employed a virtual reality perception experiment to analyze the relationship between significant spatial indicators and perceived density by investigating 16 high-density residential layout models in 3 configurations: Tower-Enclosed, Balanced Slab-Enclosed, and Staggered Slab-Enclosed. The results indicate that: (1) greater building height intensifies perceived density, leading to sensations of overcrowding and discomfort; (2) an increased sky ratio mitigates perceived density, fostering a more open and pleasant environment; (3) recessed residential facades enhance residents’ density perception; and (4) Staggered Slab-Enclosed Layout configurations receive the most favorable evaluations regarding perceived density. The authors attempt to go beyond current regulations to propose tailored solutions for Shenzhen’s high-density context, improving spatial efficiency and residential comfort in future public housing designs. The finding provides scientific evidence to support urban planners and policymakers in developing more resilient and sustainable high-density neighborhoods. Full article

This study adapted the mean age of air, a time scale widely utilized in evaluating indoor ventilation, to assess the impact of building layouts on urban ventilation capacity. To distinguish it from its applications in enclosed indoor environments, the adapted index was termed the effective mean age of air (${\overline{\tau }}_E$). Based on an experimentally validated method, computational fluid dynamic (CFD) simulations were performed for parametric studies on four generic parameters that describe urban morphologies, including building height, building density, and variations in the heights or frontal areas of adjacent buildings. At the breathing level (z = 1.7 m), the results indicated three distinct distribution patterns of insufficiently ventilated areas: within recirculation zones behind buildings, in the downstream sections of the main road, or within recirculation zones near lateral facades. The spatial heterogeneity of ventilation capacity was emphasized through the statistical distributions of ${\overline{\tau }}_E$. In most cases, convective transport dominates the purging process for the whole canopy zone, while turbulent transport prevails for the pedestrian zone. Additionally, comparisons with a reference case simulating an open area highlighted the dual effects of buildings on urban ventilation, notably through the enhanced dilution promoted by the helical flows between buildings. This study also serves as a preliminary CFD practice utilizing ${\overline{\tau }}_E$ with the homogenous emission method, and demonstrates its capability for assessing urban ventilation potential in urban planning. Full article

With rapid urbanization, the urban heat island (UHI) effect has intensified, posing challenges to human health and ecosystems. This study explores the impact of sunlight exposure areas of artificial structures and human activities on land surface temperature (LST) in Hefei and Xuzhou, using Landsat 9 data, Google imagery, nighttime light data, and Point of Interest (POI) data. Building shadow distributions and urban road surface areas were derived, and geospatial analysis methods were applied to assess their impact on LST. The results indicate that the sunlight exposure areas of roofs and roads are the primary factors affecting LST, with a more pronounced effect in Xuzhou, while anthropogenic heat plays a more prominent role in Hefei. The influence of sunlight exposure on building facades is relatively weak, and population density shows a limited impact on LST. The geographical detector model reveals that interactions between roof and road sunlight exposure and anthropogenic heat are key drivers of LST increases. Based on these findings, urban planning should focus on optimizing building layouts and heights, enhancing greening on roofs and roads, and reducing the sunlight exposure areas of artificial structures. Additionally, strategically utilizing building shadows and minimizing anthropogenic heat emissions can help lower local temperatures and improve the urban thermal environment. Full article

Novelty architecture buildings can be tiled with conventional rectangular solar photovoltaic (PV) modules with both close-packed cells or partially transparent modules, vastly increasing renewable energy, reducing carbon emissions, and allowing for positive energy buildings. To enable this potential, in this study, for the first time, two open-source programs were developed and integrated to provide a foundation for designing and coating real-life novelty architecture buildings and objects with solar PV modules. First, a tiling algorithm was proposed and integrated into Blender that can generate solar PV modules on the face of any 3D model, and an augmented Python version of SAM was developed to simulate the performance of the resultant irregularly shaped PV systems. The integrated open-source software was used to analyze the energy performance of seven different novelty BIPVs located across the globe. The buildings’ energy performance was compared to conventional ground-based PV systems, and the results showed that the conventional arrays generate more energy per unit power than the BIPVs. The analysis reveals that the more complex the building model geometry, the less energy the building generates; however, the novelty BIPV power and energy densities far surpass conventional ground-based PV. The real estate savings observed were substantial, reaching 170% in one case where the BIPV reached 750 m in height. The BIPVs’ energy production is optimized by orienting the building via rotation and only needs to be carried out a single time for replication anywhere globally. The results show that the energy yield of the BIPV increases as the building becomes more detailed while the total power and energy decrease, indicating the need for the careful balancing of priorities in building design. Finally, the energy simulations demonstrate the potential for net-positive energy buildings and contribute to net-zero-emission cities. The findings indicate that BIPVs are not only appropriate for conventional residential houses and commercial buildings, but also for historical building replicas or monuments in the future. Further studies are needed to investigate the structural, electrical, and socio-economic aspects of novelty-architecture BIPVs. Full article

In order to reduce CO₂ emissions in the brick manufacturing process, the effectiveness of the energy-intensive firing process needs to be improved. This can be achieved by enhancing the heat transfer in order to reduce firing times. As a result, current development of tunnel kilns is oriented toward fast firing as a long-term goal. However, a struggling building sector and complicated challenges, such as different requirements for product quality, have impeded developments in this direction. This creates potential for the further development of oven designs, such as improved airflow through the kiln. In this article, numerical flow simulations are used to investigate two different reconstruction measures and compare them to the initial setup. In the first measure, the kiln height is reduced, while in the second measure, the kiln cars are adjusted to alternate the height of the bricks so that every other pair of bricks is elevated, creating a staggered arrangement. Both measures are investigated to determine the effect on the heating rate compared to the initial configuration. A transient grid independence study is performed, ensuring numerical convergence and the setup is validated by experimental results from measurements on the initial kiln configuration. The simulations show that lowering the kiln height improves the heat transfer rate by $40\%$, while the staggered arrangement of the bricks triples it. This leads to an average brick temperature after two hours which is around 130 °C higher compared to the initial kiln configuration. Therefore, the firing time can be significantly reduced. However, the average pressure loss coefficient rises by $70\%$ to $90\%$, respectively, in the staggered configuration. Full article

Accurate estimation of building height is crucial for urban aesthetics and urban planning as it enables an accurate calculation of the shadow period, the effective management of urban energy consumption, and thorough investigation of regional climatic patterns and human-environment interactions. Although three-dimensional (3D) cadastral data, ground measurements (total station, Global Positioning System (GPS), ground laser scanning) and air-based (such as Unmanned Aerial Vehicle—UAV) measurement methods are used to determine building heights, more comprehensive and advanced techniques need to be used in large-scale studies, such as in cities or countries. Although satellite-based altimetry data, such as Ice, Cloud and land Elevation Satellite (ICESat-2) and Global Ecosystem Dynamics Investigation (GEDI), provide important information on building heights due to their high vertical accuracy, it is often difficult to distinguish between building photons and other objects. To overcome this challenge, a self-adaptive method with minimal data is proposed. Using building photons from ICESat-2 and GEDI data and building footprints from the New York City (NYC) and Los Angeles (LA) open data platform, the heights of 50,654 buildings in NYC and 84,045 buildings in LA were estimated. As a result of the study, root mean square error (RMSE) 8.28 m and mean absolute error (MAE) 6.24 m were obtained for NYC. In addition, 46% of the buildings had an RMSE of less than 5 m and 7% less than 1 m. In LA data, the RMSE and MAE were 6.42 m and 4.66 m, respectively. It was less than 5 m in 67% of the buildings and less than 1 m in 7%. However, ICESat-2 data had a better RMSE than GEDI data. Nevertheless, combining the two data provided the advantage of detecting more building heights. This study highlights the importance of using minimum data for determining urban-scale building heights. Moreover, continuous monitoring of urban alterations using satellite altimetry data would provide more effective energy consumption assessment and management. Full article

The development height of a water-flowing fractured zone is the key parameter to consider when carrying out mining under water pressure and coal mining with water conservation. In this paper, Jurassic coal seam 3-1 in the Menkeqing Coal Mine was taken as the research target, and a three-dimensional mining geological model was established by using FLAC^3D to study the deformation and failure rules of overburden. Three roof boreholes were drilled in the auxiliary transportation roadway of adjacent working faces for dynamic monitoring by the resistivity method, which can better observe the whole process from failure to stability of the overburden. The results show that due to the complex sedimentary environment and large buried depth of coal seams in western China, there is a large deviation between the calculation results of the empirical formula of the fractured zone height under the “Regulations of buildings, water, railway and main well lane leaving coal pillar and press coal mining” (three regulations) and the simulation and on-site measurement. Based on the comprehensive analysis, the influence range of mining advance abutment pressure is approximately 60 m. The height of the water-flowing fractured zone is approximately 106 m, and it is located at the interface between sandy mudstone and mudstone. The height of the caving zone is approximately 22 m, and it is located at the interface between fine sandstone and medium sandstone. The ratio of the fractured height and coal seam thickness (R_f) reached 24.4, which was basically consistent with the test result of the adjacent Yushenfu mining area (which was 26 on average). There is no obvious change in the development height of the caving zone and water-flowing fracture zone from the working face to the drilling borehole position of more than 120 m, which reflects that the height of the overburden failure zone is related to the control of lithological combination. Full article