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This paper focuses on oxidation reactivity and nanostructural characteristics of particulate matter (PM) emitted from diesel engine fuelled with different volume proportions of diesel/polyoxymethylene dimethyl ethers (PODEn) blends (P0, P10 and P20). PM was collected using a metal filter from the exhaust manifold. The collected PM samples were characterized using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The TGA results indicated that the PM produced by P20 had the highest moisture and volatility contents and the fastest oxidation rate of solid carbon followed by P10 and P0 derived PM. SEM analysis showed that PM generated from P20 was looser with a lower mean value than PM emitted from P10 and P0. Quantitative analysis of high-resolution TEM images presented that fringe length was reduced along with increased separation distance and tortuosity with an increase in PODEn concentration. These trends improved the oxidation reactivity. According to Raman spectroscopy data, the intensity, full width at half-maximum and intensity ratio of the bands also changed demonstrating that PM nanostructure disorder was correlated with a faster oxidation rate. The results show the use of PODEn affects the oxidation reactivity and nanostructure of PM that is easier to oxidize.

Magneto-sensitive elastomers (MSEs) are composite materials with ferromagnetic particles embedded in rubber matrices. Their mechanical properties can be changed by applying an external magnetic field. Although their stiffness and damper properties have been extensively studied, only a few studies have been involved with their magnetostriction behaviors, which have potential applications in sensors. To observe the interaction mechanisms between mechanical and magnetic fields and to investigate the magnetostrictive effect numerically, a novel magneto-structural coupling algorithm was developed. A magnetostrictive test system was also developed and fabricated for validating the simulation method. Several MSE samples embedded with millimeter-sized particles were fabricated and tested. The simulation results agreed well with the experimental results. Also both of them showed negative magnetostrictive strains for the specified samples and test conditions in this study. The contributions of four influencing factors were evaluated, and some results were concluded. Before magnetic saturation, the bigger the magnetic field strength is, the stronger the magnetostrictive effect is, and their relationship follows a quadratic polynomial expression. The closer the distance between two adjacent particles is, the stronger the magnetostrictive effect is, and their relationship satisfies a cubic polynomial equation. The higher the particle volume fraction is, the stronger the magnetostrictive effect is, and there is a linear relationship between them. The particle diameter has little influence on the magnetostrictive effect.

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The connection cones between an exhaust pipe and an exhaust after-treatment system (EATS) will affect the flow into the first monolith. In this study, a new streamlined connection cone using non-uniform rational B-splines (NURBS) is applied to optimize the flow uniformity inside two different monoliths (a gasoline particulate filter and an un-coated monolith). NURBS and conventional cones were created using 3D printing with two different cone angles. The velocities after the monolith were collected to present the uniformity of the flows under different cones and different velocities. The test results indicate that NURBS cones exhibit better performance. Furthermore, all of the pressure drops of the bench test were measured and compared with those of the conventional cones, demonstrating that the NURBS cones can reduce the pressure drop by up to 12%. The computer fluid dynamics simulations depict detailed changes in the flow before and after entering the monolith. The results show that the NURBS cone avoids the generation of a recirculating zone associated with conventional cones and creates a more uniform flow, which causes a lower pressure drop. Meanwhile, the package structure of the NURBS cone can reduce the space requirements. Finally, the implications of the flow distributions are discussed.

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The airflow dynamics observed during a cough process in a CT-scanned respiratory airway model were numerically analyzed using the computational fluid dynamics (CFD) method. The model and methodology were validated by a comparison with published experimental results. The influence of the cough peak flow rate on airflow dynamics and flow distribution was studied. The maximum velocity, wall pressure, and wall shear stress increased linearly as the cough peak flow increased. However, the cough peak flow rate had little influence on the flow distribution of the left and right main bronchi during the cough process. This article focuses on the mathematical and numerical modelling for human cough process in bioengineering.