Effect of solid particle loading on nucleophilic addition of epoxy-resin to isophorone diisocyanate

In the preparation of surface coatings made of conductive composites consisting of conductive particulate fillers in a soft matrix, cracks will develop with increase of the particulate loading, which is believed to be related to the nucleophilic addition reaction between glycidyl end-capped poly （bisphenol A-co-epichlorohydrin） and isophorone diisocyanate molecules. This curing reaction is responsible for the generation of crosslinking network throughout the coatings. The influence of solid particle loading on the chemical reaction may be described as a volume-excluded effect, that is, the high solid particle loading will occupy the space between the functional groups thus preventing the chemical reaction to take place. As a direct consequence, the cross-linking network cannot develop properly due to the insufficiency of curing reaction. This will lead to the generation of cracks, as was supported by FT-IR analysis in this work.

Obtaining vehicle parameters from bridge dynamic response:a combined semi-analytical and particle filtering approach

Dynamic load imposed on the bridge by mov- ing vehicle depends on several bridge-vehicle parameters with various uncertainties. In the present paper, particle filter technique based on conditional probability has been used to identify vehicle mass, suspension stiffness, and damping including tyre parameters from simulated bridge accelerations at different locations. A closed-form expres- sion is derived to generate independent response samples for the idealized bridge-vehicle coupled system consider- ing spatially non-homogeneous pavement unevenness. Thereafter, it is interfaced with the iterative process of particle filtering algorithm. The generated response sam- ples are contaminated by adding artificial noise in order to reflect field condition. The mean acceleration time history is utilized in particle filtering technique. The vehicle- imposed dynamic load is reconstructed with the identified parameters and compared with the simulated results. The present identification technique is examined in the presence of different levels of artificial noise with bridge response simulated at different locations. The effect of vehicle velocity, bridge surface roughness, and choice of prior probability density parameters on the efficiency of the method is discussed.

CFD-DEM simulation of high density particles fluidization behaviors in 3D conical spouted beds

The spouted bed has been used in the coating process of high-density nuclear fuel particle.The particle fluidization behaviors in pseudo-2D and 3D spouted beds were simulated and validated.The effects of four independent variables(cone angle,particle density,inlet gas velocity,and particle loading)on particle fluidization behaviors in the 3D spouted bed were investigated systematically.The cone angle effect on fluidization mechanism was studied quantitatively first time.A new fluidization quality index was proposed based on the particle entrainment principle,and an extreme value was obtained when the cone angle was 60°,considered to be the optimum value for the 3D conical spouted bed.It was indicated the gas–solid contact efficiency can be kept up if the gas velocity was proportional to ρ_(p)^(0.65) and N_(p)^(0.78) when the particle density or loading was increased.These results will be useful for geometry and operation parameters design of the 3D conical spouted bed and helpful for developing the fluidization mechanism of high-density particles.

Flow instability of nanofuilds in jet

The flow instability of nanofluids in a jet is studied numerically under various shape factors of the velocity profile, Reynolds numbers, nanoparticle mass loadings,Knudsen numbers, and Stokes numbers. The numerical results are compared with the available theoretical results for validation. The results show that the presence of nanoparticles enhances the flow stability, and there exists a critical particle mass loading beyond which the flow is stable. As the shape factor of the velocity profile and the Reynolds number increase, the flow becomes more unstable. However, the flow becomes more stable with the increase of the particle mass loading. The wavenumber corresponding to the maximum of wave amplification becomes large with the increase of the shape factor of the velocity profile, and with the decrease of the particle mass loading and the Reynolds number. The variations of wave amplification with the Stokes number and the Knudsen number are not monotonic increasing or decreasing, and there exists a critical Stokes number and a Knudsen number with which the flow is relatively stable and most unstable,respectively, when other parameters remain unchanged. The perturbation with the first azimuthal mode makes the flow unstable more easily than that with the axisymmetric azimuthal mode. The wavenumbers corresponding to the maximum of wave amplification are more concentrated for the perturbation with the axisymmetric azimuthal mode.

Using the discrete element method to assess the mixing of polydisperse solid particles in a rotary drum

Despite the wide applications of powder and solid mixing in industry, knowledge on the mixing of polydisperse solid particles in rotary drum blenders is lacking. This study investigates the mixing of monodisperse, bidisperse, tridisperse, and polydisperse solid particles in a rotary drum using the dis- crete element method. To validate the model developed in this study, experimental and simulation results were compared. The validated model was then employed to investigate the effects of the drum rotational speed, particle size, and initial loading method on the mixing quality. The degree of mixing of polydis- perse particles was smaller than that for monodisperse particles owing to the segregation phenomenon. The mixing index increased from an initial value to a maximum and decreased slightly before reaching a plateau for bidisperse, tridisperse, and polydisperse particles as a direct result of the segregation of par- ticles of different sizes. Final mixing indices were higher for polydisperse particles than for tridisperse and bidisperse particles. Additionally, segregation was weakened by introducing additional particles of intermediate size. The best mixing of bidisperse and tridisperse particles was achieved for top-bottom smaller-to-larger initial loading, while that of polydisperse systems was achieved using top-bottom smaller-to-larger and top-bottom larger-to-smaller initial loading methods.

Semi-analytical and computational investigation of different dust loading structures affecting the performance of a fibrous air filter

In this study, a semi-analytical model was developed to illustrate the relationship between filtration performance （filtration efficiency and pressure drop） and dust loading under two different particle deposit structures based on theoretical analysis and computational fluid dynamic （CFD） technology. Under the compact deposit structure, within the practical parameter ranges （fiber diameter, air velocity, dust loading mass）, a slight efficiency enhancement （∽10%） occurred at the most penetration particle size （MPPS） and pressure drop increased significantly （∽100%） in response to the solidity increase from 5% to 15%. However, under the dendritic particle deposit structure, both filtration efficiency （∽40%） and pressure drop （4600%） increased significantly with the same solidity increase due to the larger air velocity and swerve change between fibers.

Solution to economic dispatch loading effect by using catfish problem with valve-point PSO algorithm

This paper proposes application of a catfish particle swarm optimization （PSO） algorithm to economic dispatch （ED） problems. The ED problems considered in this paper include valve-point loading effect, power balance constraints, and generator limits. The conventional PSO and catfish PSO algorithms are applied to three different test systems and the solutions obtained are compared with each other and with those reported in literature. The comparison of solutions shows that catfish PSO outperforms the conventional PSO and other methods in terms of solution quality though there is a slight increase in computational time.