Current Issue : January-March Volume : 2023 Issue Number : 1 Articles : 5 Articles
In recent years, with the steady and rapid growth of the national economy, various industries have developed rapidly and the resulting fire accidents have also been on the rise. This study mainly discusses the control system of a fire rescue robot for a highrise building design. Robot fire detection method involves obtaining the video image of the fire detection area through a highdefinition camera, performing image preprocessing on the current frame image of the video in the robot operating system to obtain the image; and performing the flame area segmentation based on the Ohta color space and the Otsu threshold segmentation algorithm on the image, to obtain the segmented image; through the interframe difference method, the preprocessed image of the previous frame is subtracted from the current frame image and the moving area of the image is segmented to obtain the segmented image; the obtained segmented image is combined with the segmented image in the robot operating system and images are intersected to obtain a segmented image with the characteristics of flame motion; based on other characteristics of the flame, flame recognition is performed on the area in the segmented image. Fires in high-rise buildings are increasing gradually, which seriously endangers the safety of human life and property. The firefighting robot and its control system play an important role in the fire protection of high-rise buildings. The purpose of this study is to analyze the disaster relief effect of a firefighting robot and control system in high-rise buildings. In this study, we use MATLAB software to model and simulate the rescue situation of a firefighting robot in high-rise buildings. The fuzzy control system established in the fuzzy logic toolbox of MATLAB can easily replace human field work and can change the control rules and membership function in the FIS editor. The results show that the rise time and adjustment time of the system are basically the same under the condition of variable load stiffness. The maximum overshoot is 0.59%, and the steady-state error is 0.19%. Themaximum overshoot is 1.0148%, and the stability error is 0.46%. It is concluded that the expert PID algorithm is efficient and practical. It can be concluded that the robot position control system adopts PID control algorithm, and the attitude control system adopts expert PID control algorithm. This research provides some value for the development and design of firefighting robots in high-rise buildings in the future and also brings important significance....
Cement mortar can be colored using color additive technology to give colorful facades to the surfaces of buildings, and to beautify the environment. In this study, weight ratios of color powder/cement at 1:80, 1:40, and 1:27, and polyacrylic emulsion/cement at a ratio of 1:5 were added as pigments to cement mortar; the fresh properties, slump, slump flow, hardened properties, compressive strength, flexural strength, ultrasonic pulse velocity, durability, surface electrical resistivity and thermal conductivity of the colored cement mortar were then examined. The results showed that adding color powder/cement at 1:80 and polyacrylic emulsion/cement at 1:5 gives the best water/cement (W/C) ratio, which equals 0.5; this can effectively improve the hardness and durability of colored cement mortar. At 28 days of aging, the strength of the various colored cement mortars was maintained at 33.1–36.8 MPa. The acrylic-based emulsion significantly improved the flexural strength of the specimen. At 91 days of aging, all of the cement mortars exceeded the control group, with an anti-bay strength of 19.9–21.7 MPa, and the strength increased with aging. Adding appropriate amounts of inorganic color powder and mixing water can effectively enhance the fresh and hardened properties and durability of the colored cement mortar, while polyacrylic emulsion may significantly improve the test pieces and flexural strength, which increases with age. Moreover, natural α-Fe2O3 (rust layer) is formed on the surface of the colored cement mortar samples through the addition of inorganic color powder that contains Fe(III) ion; this prevents the intrusion of noxious ions and thus increases the durability. All of the test pieces of colored cement mortar in this study had a surface resistance of over 20 kΩ-cm on the seventh day of the test period, meaning good surface compactness. In addition, because the thermal conductivity of the added inorganic color powder was higher than that of cement, the thermal conductivity was significantly improved....
In cold regions, rock’s load-bearing capacity will be greatly diminished in severe settings. This research investigates the influence of freezing and thawing on the physical and mechanical characteristics of sandstone, as well as the strength under complicated stress conditions. Uniaxial compression of sandstone samples was performed following freeze-thaw cycles, and the changes in elastic modulus and peak stress of dry sandstone and saturated sandstone were investigated under various freeze-thaw cycles. ANOVA was used to analyze whether there were significant differences between the number of freeze-thaw cycles and the peak strength and elastic modulus. A three-parameter strength prediction model based on σC, k0, and m is created based on the critical failure energy function. Experimental data is utilized to assess the model’s correctness, and the model is used to forecast the strength of dry and saturated sandstone during freeze-thaw cycles. The result indicates that peak stress and elastic modulus of dry and saturated sandstone show a steady attenuation pattern as the number of freeze-thaw cycles increases. Brittle failure is the failure mode of dry sandstone, whereas brittle failure to plastic failure is the failure mode of saturated sandstone. After 60 freezethaw cycles, peak stress in dry and saturated sandstone was reduced by 55.3% and 56.8%, respectively. The three-parameter model can predict the triaxial compressive strength of specimens under different confining pressures through the uniaxial compressive strength of specimens with an error range of 1% to 13%....
The advancement in steel fabrication technology extends the structural and constructional advantages of cellular steel beams into arched cellular steel structure members. However, less attention is given to understanding the in-plane and out-of-plane structural behavior and performance of arched cellular steel beams. This article presents a numerical study using the finite element package ABAQUS to investigate the effect of arch axis geometry (circular and parabolic) and the impact of end support types on the inplane inelastic buckling strength and buckling mode of I-section arched cellular steel beams. In the nonlinear finite element analysis of the model material nonlinearity, a second-order effect due to large deformation and initial geometric imperfection was incorporated in predicting inelastic buckling load and buckling mode. Furthermore, finite element analysis results were verified by comparing them to the existing experimental work. Test models covering shallow to deep arches of subtended angle in a range of 45–180 were investigated under uniformly distributed vertical loads and mid-span point loads. It was found that nonlinear finite element results fairly replicate the experimental work in predicting inelastic buckling load and post-buckling behavior. From the parametric investigation, it was found that deep parabolic arched cellular steel beams are structurally more efficient than their equivalent circular arched cellular steel beams. Pinned in-plane and free out-of-plane end support conditions result in a reduced inelastic ultimate buckling load capacity of arched cellular steel members when compared to other possible end support types. The geometry of an arch axis has no noticeable impact on the buckling mode of arched cellular steel beams....
The environment receives millions of tons of garbage, including plastic and glass, and concrete building debris contributes to a number of environmental problems. In order to reduce cement and make use of waste materials like glass and plastic, this research creates compacted concrete samples using waste glass powder, waste plastic powder, micro-silica, fly ash, and recycled powdered concrete. Compressive, nonlinear behavior, and SEM tests on compacted specimens showed that by removing 80% of the cement and substituting 20% recycled concrete powder, 15% micro-silica, 15% fly ash, 15% waste plastic powder, and 15% waste glass powder (at 80°C for 20 minutes), sustainable concrete with compressive and flexural strengths nearly equal to the sample’s compressive and flexural strengths was produced. Micro-silica has several shortcomings regarding improving concrete strength and building a suitable combination with recycled concrete powder. In extremely small quantities, glass powder may be used to replace cement, and in greater quantities, it can take the place of aggregate. Finally, it was found that concrete mortar could be made completely sustainable by using recycled materials like glass, plastic, and recycled concrete, as well as micro-silica and fly ash, and that only 20% of the weight of cement could be used without lowering the compressive and flexural strength of the concrete....
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