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  • Towards No-Reference Image Quality Assessment Based on Multi-Scale Convolutional Neural Network
  • Abstract Image quality assessment has become increasingly important in image quality monitoring and reliability assuring of image processing systems. Most of the existing no-reference image quality assessment methods mainly exploit the global information of image while ignoring vital local information. Actually, the introduced distortion depends on a slight difference in details between the distorted image and the non-distorted reference image. In light of this, we propose a no-reference image quality assessment method based on a multi-scale convolutional neural network, which integrates both global information and local information of an image. We first adopt the image pyramid method to generate four scale…
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  • Closed Solution for Initial Post-Buckling Behavior Analysis of a Composite Beam with Shear Deformation Effect
  • Abstract This paper is focused on the post-buckling behavior of the fixed laminated composite beams with effects of axial compression force and the shear deformation. The analytical solutions are established for the original control equations (that is not simplified) by applying the Maclaurin series expansion, Chebyshev polynomials, the harmonic balance method and the Newton’s method. The validity of the present method is verified via comparing the analytical approximate solutions with the numerical ones which are obtained by the shooting method. The present third analytical approximate solutions can give excellent agreement with the numerical solutions for a wide range of the deformation…
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  • Modeling and Simulation of Valve Cycle in Vein Using an Immersed Finite Element Method
  • Abstract A vein model was established to simulate the periodic characteristics of blood flow and valve deformation in blood-induced valve cycles. Using an immersed finite element method which was modified by a ghost fluid technique, the interaction between the vein and blood was simulated. With an independent solid solver, the contact force between vein tissues was calculated using an adhesive contact method. A benchmark simulation of the normal valve cycle validated the proposed model for a healthy vein. Both the opening orifice and blood flow rate agreed with those in the physiology. Low blood shear stress and maximum leaflet stress were…
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  •   Views:98       Downloads:95        Download PDF
  • A Coupled Cavitation Model in an Oscillatory Oil Squeeze Film
  • Abstract In this paper, the oscillatory oil squeeze film is taken as a research object, and a coupled cavitation model based on the theory of bubble dynamics and hydrodynamic lubrication is used and a specific method of numerical calculation is given. Then the parallel-plate squeeze film test apparatus is used to validate the coupled cavitation model. The pictures of the cavitation were captured by a high-speed camera and then processed to obtain the variation of the cavitation area in experiments. Compared with the experimental results, the model can successfully predict the process of generation and development of cavitation. At the same…
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  •   Views:92       Downloads:80        Download PDF
  • Effect Mechanisms of Hygrothermal Environments on Failure of Single-Lap and Double-Lap CFRP-Aluminum Bolted Joints
  • Abstract The high demands for load-carrying capability and structural efficiency of composite-metal bolted joints trigger in-depth investigations on failure mechanisms of the joints in hygrothermal environments. However, few studies have been presented to exhaustively reveal hygrothermal effects on the failure of CFRP-metal bolted joints, which differ from CFRP-CFRP or metal-metal bolted joints because of the remarkably different material properties of CFRPs and metals. In this paper, hygrothermal effects on tensile failures of single-lap and double-lap CFRP-aluminum bolted joints were experimentally and numerically investigated. A novel numerical model, in which a hygrothermal-included progressive damage model of composites was established and elastic-plastic models…
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  •   Views:93       Downloads:83        Download PDF
  • Two-Layer Contact Nonlinear Mechanical Analysis of Flexible Drilling Tool in the Wellbore
  • Abstract The lack of research on flexible drilling tool leads to limited application of ultra-short radius horizontal wells. The flexible drilling tool is different from the conventional drilling tool. The flexible drilling pipe involves a mutual transition between the structure and the mechanism during the deformation process. At the same time, the flexible drilling pipe and the eccentric guide tube, the guide tube and the wellbore generate random contact. In this paper, 3-D beam elements, universal joint elements, rigid beam elements and the beam-beam contact elements are combined to establish a two-layer contact nonlinear finite element model of the flexible drilling…
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  •   Views:92       Downloads:87        Download PDF
  • Simulation of Daily Diffuse Solar Radiation Based on Three Machine Learning Models
  • Abstract Solar radiation is an important parameter in the fields of computer modeling, engineering technology and energy development. This paper evaluated the ability of three machine learning models, i.e., Extreme Gradient Boosting (XGBoost), Support Vector Machine (SVM) and Multivariate Adaptive Regression Splines (MARS), to estimate the daily diffuse solar radiation (Rd). The regular meteorological data of 1966-2015 at five stations in China were taken as the input parameters (including mean average temperature (Ta), theoretical sunshine duration (N), actual sunshine duration (n), daily average air relative humidity (RH), and extra-terrestrial solar radiation (Ra)). And their estimation accuracies were subjected to comparative analysis.…
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  • A Geometrical Approach to Compute Upper Limb Joint Stiffness
  • Abstract Exoskeletons are designed to control the forces exerted during the physical coupling between the human and the machine. Since the human is an active system, the control of an exoskeleton requires coordinated action between the machine and the load so to obtain a reciprocal adaptation. Humans in the control loop can be modeled as active mechanical loads whose stiffness is continuously changing. The direct measurement of human stiffness is difficult to obtain in real-time, thus posing a significant limitation to the design of wearable robotics controllers. Electromyographic (EMG) recordings can provide an indirect estimation of human muscle force and stiffness,…
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  •   Views:116       Downloads:113        Download PDF
  • Hybrid LES/URANS Simulation of Rayleigh-Bénard Convection Using BEM
  • Abstract In this paper, we develop and test a unified hybrid LES/URANS turbulence model with two different Large Eddy Simulation (LES) turbulence models. The numerical algorithm is based on the Boundary Element Method. In the existing hybrid LES/URANS turbulence model we implemented a new Smagorinsky LES turbulence model. The hybrid LES/URANS turbulence model is unified, which means that the LES/URANS interface is changed dynamically during simulation using a physical quantity. In order to define the interface between LES and unsteady Reynolds Averaged Navier Stokes (URANS) zones during the simulation, we use the Reynolds number based on turbulent kinetic energy as a…
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  •   Views:137       Downloads:182        Download PDF
  • A Numerical Algorithm Based on Quadratic Finite Element for Two-Dimensional Nonlinear Time Fractional Thermal Diffusion Model
  • Abstract In this article, a high-order scheme, which is formulated by combining the quadratic finite element method in space with a second-order time discrete scheme, is developed for looking for the numerical solution of a two-dimensional nonlinear time fractional thermal diffusion model. The time Caputo fractional derivative is approximated by using the L2 -1 σ formula, the first-order derivative and nonlinear term are discretized by some second-order approximation formulas, and the quadratic finite element is used to approximate the spatial direction. The error accuracy O(h 3 + ∆t 2 ) is obtained, which is verified by the numerical results.
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  •   Views:188       Downloads:227        Download PDF
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