In this paper, experimental works of 19 impacted high-strength steel circular hollow section (HSCHS) specimens and one non-impacted specimen were carried out, to obtain their axial residual compressive performance sub...
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This paper presents a quadrant analysis of turbulent rotor wakes, placing a particular emphasis on the self-similarity in single-point turbulent statistics. The self-similarity analysis reveals that within the wake se...
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This paper presents a quadrant analysis of turbulent rotor wakes, placing a particular emphasis on the self-similarity in single-point turbulent statistics. The self-similarity analysis reveals that within the wake self-similar region, the distribution of the Reynolds shear stress −u′v′¯ and the turbulent kinetic energy k in different quadrants can also attain a state of self-similarity. The length scaling is the same for −u′v′¯, k, and their different quadrant contributions. However, the velocity scaling of the ejection contribution differs from that of −u′v′¯ and k. Additionally, the analysis of hole filtering and spectrum filtering effects on the self-similarity and scaling of the ejection contribution to −u′v′¯ reveals a strong connection between ejection events and large-scale coherent structures, as well as deceleration extreme events. This finding is further confirmed through quadrant analysis of the time evolution of velocity fluctuations. The present study can be helpful in improving our understanding of the turbulent wake self-similarity.
In our country, there are 60 billion square meters of existing leasable area, reactive powder concrete (RPC) has the characteristics of high toughness and high strength-to-weight ratio. RPC strengthened concrete (RC) ...
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A new syntactic foam material was prepared by screening three different average particle sizes of cenospheres(150,200,and 300μm)from industrial waste fly *** impact testing on syntactic foam filler and foam-filled tu...
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A new syntactic foam material was prepared by screening three different average particle sizes of cenospheres(150,200,and 300μm)from industrial waste fly *** impact testing on syntactic foam filler and foam-filled tubes was conducted using a drop hammer test *** effects of parameters,such as the size of cenospheres and the impact velocity,on the mechanism of deformation,mechanical characteristics,and capacity for energy absorption of the specimen were *** this basis,the differences in compressive properties exhibited by the syntactic foam-filled tubes under the two loading conditions were *** results indicate that with the decrease in the average diameter of cenospheres,the initial peak crushing load and mean crushing load of foam-filled tubes increase,while the compression efficiency *** specific energy absorption(SEA)of the syntactic foam-filled tube can reach 25 J/*** the increase of impact velocity,the SEA of the specimen increases *** was demonstrated that the syntactic foam-filled tube exhibits a higher effective energy absorption ratio under impact loading compared to quasi-static loading.
An isolated slit was placed in a single box girder to obtain passive leading-edge suction and trailing-edge jet flow to control the unsteady aerodynamic force and modify the flow *** Great Belt East Bridge was used as...
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An isolated slit was placed in a single box girder to obtain passive leading-edge suction and trailing-edge jet flow to control the unsteady aerodynamic force and modify the flow *** Great Belt East Bridge was used as a physical model at a geometric scale of 1:*** tunnel experiments were conducted at an incoming airflow speed of 10 m/s,and the Reynolds number was calculated as 2.3×104 using the test model height and wind *** surface pressure distribution was measured,and the aerodynamic force acting on the test model with and without the isolated slit was calculated by integrating the pressure *** was found that the control using an isolated slit can dramatically decrease the fluctuating surface pressure distribution and aerodynamic *** analysis on the power spectral density of the lift force revealed that the isolated slit accelerated vortex ***,high-speed particle image velocimetry was used to investigate the wake flow structure behind the test model.A vortex separated from the upper surface was pushed to a lower location and the wake flow structure was modified by the isolated slit.A proper orthogonal decomposition(POD)of the flow field showed that the first two POD modes in the controlled case contributed less energy than those in the uncontrolled case,indicating that more energy was transferred to higher modes,and small-scale vortices had more energy.A secondary instability structure was found in the wake flow for a nondimensional jet momentum coefficient J of 0.0667.
Curved steel-plate composite (SC) walls are widely used in nuclear engineering due to their advantages in seismic performance and modular construction. This study tested the axial compression performance of five curve...
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A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modifie...
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A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modified reaction acceleration method is adopted and validated in the three-dimensional model. Seven ground motions are selected and the peak ground acceleration is adjusted to 0.2 g, 0.4 g and 0.6 g. The impact of the void ratio and thickness of the porous shock absorption layer is studied, while the surrounding rock grade and tunnel depth are also investigated. The numerical results show that the porous shock absorption layer has good shock absorption performance and can effectively reduce the maximum internal force of the secondary lining, but it cannot reduce the maximum horizontal relative displacement of the secondary lining. The circumferential rubber strip in the porous shock absorption layer will reduce shock absorption performance. The results of parameter analysis indicate that the shock absorption performance of the porous shock absorption layer increases with the increase of the void ratio and thickness, and it has good shock absorption performance under different surrounding rock grades and tunnel depths.
This paper focuses on energy harvesting and smart controls in concrete structures using both experimental and theoretical approaches. The growing demand for sustainable energy solutions has led to innovations in mater...
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This paper focuses on energy harvesting and smart controls in concrete structures using both experimental and theoretical approaches. The growing demand for sustainable energy solutions has led to innovations in materials like concrete, which offer energy conversion and efficient control possibilities. This study introduces a novel concept for concrete structures using piezoelectric nanoparticles, specifically zinc oxide nanoparticles (ZnO), offering three key benefits: (a) enhanced strength, (b) energy harvesting and storage, and (c) smart control. The experimental phase involves modifying concrete structures with energy harvesting technologies. Dispersion of nanoparticles in water is a key challenge, addressed through magnetic stirring, ultrasonic homogenization, and mechanical stirring. Multiple concrete specimens with nanoparticles were produced, followed by tests including compressive strength assessments, energy harvesting under mechanical loads, and intelligent control of concrete deflection through voltage application. On the theoretical front, modeling and numerical methods predict the behavior of energy harvesting concrete structures. The precise five-parameter theory, accounting for Poisson's effect, is employed for modeling. After deriving governing equations, differential quadrature numerical technique computes deflection and output voltage. Comparisons and validations are made between experimental and simulation results. The experiments reveal that the optimal ZnO nanoparticle content is 0.9%, leading to significant compressive strength improvements of 22.14%, 27.31%, and 34.28% for 7, 14, and 28-day samples, respectively, compared to controls. Beyond this content, compressive strength diminishes. Moreover, 0.9% ZnO-concrete produces an output voltage of 32 volts, well-justified technically and economically. Additionally, +50V voltage induces 9.2mm deformation, while -50V voltage yields 5.8mm, showcasing a substantial 63% deformation alteration potenti
Edge detection is one of the most challenging tasks in computer vision due to the complexity of various objects and backgrounds. Previous efforts in edge detection often faced significant difficulties, resulting in ma...
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The rubble generated by the massive collapse of street-front buildings after an earthquake can seriously block roads, affecting the connectivity of the road network in a city and causing serious damage. In order to ac...
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