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.
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
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.
Traditional manual methods for on-site quality measurement are often inefficient. Existing robots, typically combining a robot dog with 3D laser scanners, encounter challenges like significant storage requirements, de...
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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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The advanced structural health monitoring system, integrating multiple types of sensors, provides a comprehensive method for monitoring structural information, effectively identifying abnormal changes, and ensuring th...
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Straw is an environmentally friendly, cost-effective, and abundant raw material for building boards. To assess the feasibility of using straw boards as alternative sheathing panels in light-steel-members such as walls...
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Straw is an environmentally friendly, cost-effective, and abundant raw material for building boards. To assess the feasibility of using straw boards as alternative sheathing panels in light-steel-members such as walls and floors, the mechanical and thermal properties of straw boards with high densities were investigated. The straw boards involved in this study include five wheat straw strand boards (WSSB12, WSSB15, WSSB18, WSSB25, and WSSB30) and a paper straw board (PSB58). Mechanical properties, including compression, tension, and bending properties, were investigated by tests and a proposed prediction method of tensile strength. In the experimental studies of compression properties, the failure modes and characteristics of load-deformation curves of compressive specimens, and the parameters of compression properties, including the strength, elastic modulus, and Poisson ratio, were analyzed and summarized, and the differences in material directivity were discussed as well. The WSSBs were found to be transverse isotropic material with brittle characteristics in the plane, while the PSB showed similar brittle characteristics in the failure stage. Furthermore, the experimental studies of bending properties and similar analyses and summaries for test results were carried out. Results show that the bending strength is less than the compressive strength for WSSBs, while the case is just the opposite for PSB, and the elastic moduli of bending and compression are close for both WSSBs and PSB. Then, finite element models (FEMs) of the bending test specimens using the user material subroutine UMAT were developed to predict the tensile strength ft, and the prediction results were qualitatively assessed based on the correlation between ft and fb, fc. As verified, the prediction results of ft are believable, and the prediction method proposed in this study is feasible. Such a prediction method could efficiently determine the tensile strength of similar brittle materials withou
When using the projection method(or fractional step method)to solve the incompressible Navier-Stokes equations,the projection step involves solving a large-scale pressure Poisson equation(PPE),which is computationally...
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When using the projection method(or fractional step method)to solve the incompressible Navier-Stokes equations,the projection step involves solving a large-scale pressure Poisson equation(PPE),which is computationally expensive and *** this study,a machine learning based method is proposed to solve the large-scale *** machine learning(ML)-block is used to completely or partially(if not sufficiently accurate)replace the traditional PPE iterative solver thus accelerating the solution of the incompressible Navier-Stokes *** ML-block is designed as a multi-scale graph neural network(GNN)framework,in which the original high-resolution graph corresponds to the discrete grids of the solution domain,graphs with the same resolution are connected by graph convolution operation,and graphs with different resolutions are connected by down/up prolongation *** well trained MLblock will act as a general-purpose PPE solver for a certain kind of flow *** proposed method is verified via solving two-dimensional Kolmogorov flows(Re=1000 and Re=5000)with different source *** the premise of achieving a specified high precision(ML-block partially replaces the traditional iterative solver),the ML-block provides a better initial iteration value for the traditional iterative solver,which greatly reduces the number of iterations of the traditional iterative solver and speeds up the solution of the *** experiments show that the ML-block has great advantages in accelerating the solving of the Navier-Stokes equations while ensuring high accuracy.
The Trombe wall is a passive solar building exterior wall system proposed by Professor Felix Trombe in France,which can collect solar energy to heat buildings without additional energy consumption,making it a focal po...
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The Trombe wall is a passive solar building exterior wall system proposed by Professor Felix Trombe in France,which can collect solar energy to heat buildings without additional energy consumption,making it a focal point of research in building energy ***,its effectiveness is constrained by the low density of solar radiation in winter and the potential for overheating in *** study introduces a novel Trombe wall designed to address these issues through a focused strategy,enabling automatic transition between heating during winter and shading during *** thermal performance parameters of the novel Trombe walls in both winter and summer seasons are examined,and their energy consumption is assessed using experimental research *** indicate that the novel Trombe wall facilitates greater energy savings in both winter and *** compared with traditional Trombe walls,the novel Trombe wall achieves a significant reduction in energy consumption,with up to 55 W/m^(2)in heating load during winter and 47 W/m^(2)in cooling load during *** introduction of this new system holds substantial potential for the realization of zero-energy buildings.
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