PERENCANAAN PENANGKAL PETIR DI GEDUNG SEKOLAH TINGGI TEKNOLOGI PEKANBARU

The installation of lightning rods is very necessary for office buildings, buildings, towers so that humans and equipment inside the building are protected from the danger of lightning strikes. This study plans a good lightning rod to be installed in the Pekanbaru Technology High School building by knowing the values ​​of lightning strike density, lightning strike distance, the level of building hazard estimates, determining the area that attracts lightning strikes, determining the number of lightning strikes per year, and determining the radius. protection against lightning strikes. The results of the research that has been carried out, in the Pekanbaru Technological School (STTP) building with a building length of 32.50 m, a building width of 22.50 m, and a building height of 18.00 m. obtained the value of lightning density N_g=35,3602 km²/year, area of ​​attraction for lightning strikes A_e=15,827.49 m², the number of lightning strikes N_d=0,559/year, has level III protection with E=082, area of ​​radius A_x=174.885.44 m², So to be safer from lightning strikes, the STTP building using an electrostatic lightning rod is enough to use 1 finial with a length of 2 m.

Evaluation Schoolyard Wind Comfort Changes Due to Rapid Developments: Case Study of Nanjing, China

(1) Background: Evaluation of wind environments regarding pedestrian comfort may unveil potential hotspot areas, particularly in the context of the rapid urban development in China since the 1990s. (2) Method: With primary schools in Nanjing as case studies, the authors simulated the wind environment of schoolyards with the computational fluid dynamics (CFD) approach and evaluated relevant wind comfort criteria. (3) Results: The study showed that the comfortable wind environment of schoolyards generally expanded in three primary schools in summer and winter, and wind speed and the comfortable wind level decreased in some outdoor schoolyard spaces. The results also indicate that the mean wind speed of the schoolyards did not linearly correlate to the building density either within or outside the schools. An increase in the building height of the primary schools could improve the wind comfort of the schoolyard, but the increased building height in the vicinity may worsen the wind comfort in the schools. Meanwhile, a lift-up or step-shaped building design for schools can improve wind comfort in schoolyards. (4) Conclusions: This study provided simulated results and an approach for urban designers to evaluate and improve the wind environment for school children’s outdoor activities.

Verifying urban canopy parameterization effects in a mesoscale model with wind tunnel data

<p>Airflow within and above urban canopy layers are modelled by different approaches in a wind tunnel and in a numerical mesoscale model. For the experimental approaches in the wind tunnel, the combination of spires, roughness elements and a physical model generates a scaled boundary layer flow with velocity and turbulence characteristics that are consistent with microscale urban canopy flows in reality. A wind tunnel is comparable in resolution with an obstacle resolving microscale model, therefore data comparisons are frequently done for this scale. However, for many applications numerical models of 1 km resolution are used, resolving mesoscale atmospheric phenomena but not microscale ones. Parameterizations are then used to represent physical processes and obstacle influences on the atmospheres. Due to the coarse resolution, a direct comparison of mesoscale model results and wind tunnel is difficult.</p> <p>In this study, we use wind tunnel data as validation datasets to evaluate the urban canopy parameterization effects on airflow in a mesoscale model. We have developed a multi-layer urban canopy parameterization using nudging, implemented in the atmospheric model METRAS. The extended model is tested in an idealized case, in which the model domain is designed using realistic topographical data for the Hamburg city center but not resolving buildings. To simplify the city structure, two important canopy morphological parameters are used: building surface fraction and building height. Experiments with a similar model configuration were carried out in parallel in the Blasius wind tunnel facility of the Environmental Wind-Tunnel Laboratory of the University of Hamburg at a model scale of 1:500. Based on the realistic building surface fraction and building height, a pyramid-like model for the urban canopy is placed in the wind tunnel. The set-ups of the numerical model runs and the wind tunnel experiments are designed following two principles: first, keeping the set-up in both approaches as equivalent as possible, in terms of meteorological conditions, roughness lengths, simulation durations, etc.; secondly, taking into account the limitations of the microscale wind tunnel datasets and keeping as many characteristics of atmospheric processes as possible.</p> <p>The METRAS results show a good agreement with the wind tunnel datasets, in terms of representing building effects such as the reduction of mean wind speeds in the building wake, enhanced turbulence intensities and turbulent fluctuation characteristics for a sufficiently fine scale. However, for coarser resolution, the result comparability reduces and the agreement is less. Thus, we conclude that sub-grid scale canopy effects can be parameterized sufficiently well for their impacts on the average flow, but any detailed changes can only be simulated with a sufficiently high resolution.</p>

Horizontal vibration response analysis of ultra-high-speed elevators by considering the effect of wind load on buildings

At present, the wind-induced vibration effects of super-high-rise buildings caused by wind loads can no longer be ignored. The wind-induced vibration effect of super-high-rise buildings will inevitably cause the vibration of ultra-high-speed elevators. However, for the study of the vibration characteristics of ultra-high-speed elevators, the wind-induced vibration effect of the ultra-high-speed elevator is often ignored. Based on Bernoulli–Euler theory, the forced vibration differential equation of elevator guide rail was established, and the vibration equation of elevator guide shoe and car was established by using the Darren Bell principle. The coupled vibration model of the guide rail, guide shoes, and car can be obtained through the relationship of force and relative displacement among these components. Based on the model, the effects of wind pressure and building height on the horizontal vibration of the ultra-high-speed guideway and passenger comfort were analyzed. The results showed that the influence of the wind load on the vibration of ultra-high-speed elevator can no longer be disregarded, and the maximum horizontal vibration acceleration of the guide rail is positively correlated with the height of building. The vibration acceleration of the same height rail increases with the increase in wind pressure. The vibration dose values (VDVs) increase with the increase in wind pressure and building height, respectively.

Developing a Method to Extract Building 3D Information from GF-7 Data

The three-dimensional (3D) information of buildings can describe the horizontal and vertical development of a city. The GaoFen-7 (GF-7) stereo-mapping satellite can provide multi-view and multi-spectral satellite images, which can clearly describe the fine spatial details within urban areas, while the feasibility of extracting building 3D information from GF-7 image remains understudied. This article establishes an automated method for extracting building footprints and height information from GF-7 satellite imagery. First, we propose a multi-stage attention U-Net (MSAU-Net) architecture for building footprint extraction from multi-spectral images. Then, we generate the point cloud from the multi-view image and construct normalized digital surface model (nDSM) to represent the height of off-terrain objects. Finally, the building height is extracted from the nDSM and combined with the results of building footprints to obtain building 3D information. We select Beijing as the study area to test the proposed method, and in order to verify the building extraction ability of MSAU-Net, we choose GF-7 self-annotated building dataset and a public dataset (WuHan University (WHU) Building Dataset) for model testing, while the accuracy is evaluated in detail through comparison with other models. The results are summarized as follows: (1) In terms of building footprint extraction, our method can achieve intersection-over-union indicators of 89.31% and 80.27% for the WHU Dataset and GF-7 self-annotated datasets, respectively; these values are higher than the results of other models. (2) The root mean square between the extracted building height and the reference building height is 5.41 m, and the mean absolute error is 3.39 m. In summary, our method could be useful for accurate and automatic 3D building information extraction from GF-7 satellite images, and have good application potential.

The Ventilation Efficiency of Urban Built Intensity and Ventilation Path Identification: A Case Study of Wuhan

Urban ventilation is being hampered by rough surfaces in dense urban areas, and the microclimate and air quality of the urban built environment are not ideal. Identifying urban ventilation paths is helpful to save energy, reduce emissions, and improve the urban ecological environment. Wuhan is the capital city of Hubei, and it has a high urban built intensity and hot summers. Taking Wuhan city, with a size of 35 km ×50 km, as an example, the built environment was divided into grids of 100 m × 100 m and included the building density, floor area ratio, and average building height. The ventilation mechanism of the urban built intensity index has previously been explained. The decrease in building density is not the sole factor causing an increase in wind speed; the enclosure and width of the ventilation path and the height of the front building are also influential. Twelve urban built units were selected for CFD numerical simulation. The ventilation efficiency of each grid was evaluated by calculating the wind speed ratio, maximum wind speed, average wind speed, and area ratio of strong wind. The relationship between the urban built intensity index and ventilation efficiency index was established using the factor analysis method and the Pearson correlation coefficient; building density and average building height are the most critical indexes of ventilation potential. In addition, the layout of the building also has an important impact on ventilation. A suitable built environment is that in which the building density is less than 30%, the average building height is greater than 15 m, and the floor area ratio is greater than 1.5. The urban built intensity map was weighted to identify urban ventilation paths. The paper provides a quantitative reference for scientific planning and design of the urban spatial form to improve ventilation.