Predicting the Floc Characteristics and Settling Velocity of Flocs under Variable Dosage of Polyacrylamide

In this study, floc characteristics such as fractal dimension and settling velocity were investigated through a flocculantion process with a polyacrylamide (PAM) flocculant over a range of suspended particle concentrations, suspension type and flocculant dosage. The floc’s structure and morphology were characterized by optical microscopy and scanning electron microscopy (SEM) methods. Floc settling velocity was measured in a settling column in a laboratory. The results showed that, the surface fractal dimension ranged from 1.044 to 1.415, which quantitatively confirmed the round and layered structure of flocs observed in SEM analyses. The PAM flocculant was proved to be more effective in flocculantion process, increasing the settling velocity. Therefore, an appropriate PAM dosage is an excellent candidate as efficient flocculant. A possible flocculantion mechanism for PAM was further analyzed. For alkaline or neutral environments, adsorption and bridging effects are dominant while charge neutralization is favored in acidic conditions.In this study, floc characteristics such as fractal dimension and settling velocity were investigated through a flocculantion process with a polyacrylamide (PAM) flocculant over a range of suspended particle concentrations, suspension type and flocculant dosage. The floc’s structure and morphology were characterized by optical microscopy and scanning electron microscopy (SEM) methods. Floc settling velocity was measured in a settling column in a laboratory. The results showed that, the surface fractal dimension ranged from 1.044 to 1.415, which quantitatively confirmed the round and layered structure of flocs observed in SEM analyses. The PAM flocculant was proved to be more effective in flocculantion process, increasing the settling velocity. Therefore, an appropriate PAM dosage is an excellent candidate as efficient flocculant. A possible flocculantion mechanism for PAM was further analyzed. For alkaline or neutral environments, adsorption and bridging effects are dominant while charge neutralization is favored in acidic conditions

NeuralMPS: Non-Lambertian Multispectral Photometric Stereo via Spectral Reflectance Decomposition

Multispectral photometric stereo(MPS) aims at recovering the surface normal of a scene from a single-shot multispectral image captured under multispectral illuminations. Existing MPS methods adopt the Lambertian reflectance model to make the problem tractable, but it greatly limits their application to real-world surfaces. In this paper, we propose a deep neural network named NeuralMPS to solve the MPS problem under general non-Lambertian spectral reflectances. Specifically, we present a spectral reflectance decomposition(SRD) model to disentangle the spectral reflectance into geometric components and spectral components. With this decomposition, we show that the MPS problem for surfaces with a uniform material is equivalent to the conventional photometric stereo(CPS) with unknown light intensities. In this way, NeuralMPS reduces the difficulty of the non-Lambertian MPS problem by leveraging the well-studied non-Lambertian CPS methods. Experiments on both synthetic and real-world scenes demonstrate the effectiveness of our method

Influences of wind and rotating speed on the fluid-structure interaction vibration for the offshore wind turbine blade

For the 5MW offshore wind turbine blade, the control and discrete equations of the fluid domain and structural domain were established respectively, and the calculation formulas of blade loads and damping coefficient were given. Furthermore, the blade entity modeling was completed by using UG and ANSYS Workbench. Based on it, the numerical calculation of blade vibration characteristics under different wind and rotating speeds was carried out, and the reliability verification was conducted by the wind tunnel test. The results of calculation indicate that the numerical results of the first principal stresses at the blade surface along the span-wise direction are consistent with the results of wind tunnel test, which verifies the reliability of the theory and numerical models. Both the influences of the bidirectional fluid-structure interaction (BFSI) and the rotation effect on the characteristics of blade vibration should be underlined. The increase of wind or rotating speed results in the nonlinear increase of the maximum span-wise displacement of the blade and of the Mises-stresses. Under different wind or rotating speed, the blade’s maximum displacement occurs at its tip, its maximum Mises-stresses appear at the relative wingspan of 0.55, and the contribution of rotating speed and average wind speed to the displacement or Mises-stress along the span-wise direction is similar