Soft magnetic composites (SMCs) contain metallic magnetic powders embedded in an insulation matrix, and are usually prepared by procedures including powder production, insulation coating, binding, compaction, and annealing. They have attracted extensive interest as fundamental electric and electronic components in the fields of energy, information, transportation, and national defense. With the development of electric and electronic devices with properties suitable for high frequency, large power, energy saving, and being electromagnetically compatible, the demand and requirements for SMCs become significantly higher. The SMC industry in China used to lag far behind overseas competitors with a huge technological gap. The main domestic products were Fe SMCs with only a small amount of alloy SMCs. Such SMCs exhibited low magnetization and unsatisfactory DC-bias properties with double the loss compared to the overseas products. Since 2002, Prof. Mi YAN’s team at Zhejiang University, China has carried out long-term cooperation with related enterprises, achieved key breakthroughs, and invented a series of new SMCs with enhanced performance and low loss. The team has also achieved large-scale production and wide application of the new SMCs, pushing the domestic industry into a world-leading position.

A trapped air pocket can cause a partial air lock in the top of a hump pipe zone. It increases the resistance and decreases the hydraulic cross section, as well as the capacity of the water supply pipeline. A hydraulic model experiment is conducted to observe the deflection and movement of the trapped air pocket in the hump pipe zone. For various pipe flow velocities and air volumes, the head losses and the equilibrium slope angles are measured. The extra head losses are also obtained by reference to the original flow without the trapped air pocket. Accordingly, the equivalent sphere model is proposed to simplify the drag coefficients and estimate the critical slope angles. To predict the possibility and reduce the risk of a hump air lock, an empirical criterion is established using dimensional analysis and experimental fitting. Results show that the extra head losses increase with the increase of the flow velocity and air volume. Meanwhile, the central angle changes significantly with the flow velocity but only slightly with the air volume. An air lock in a hump zone can be prevented and removed by increasing the pipe flow velocity or decreasing the maximum slope of the pipe.

The beam element in FLAC^3D can be used to simulate the supporting arch in a tunnel. However, this approach has the shortcoming of its constitutive model, and the bearing capacity and surrounding rock supporting effect of the arch model will be significantly exaggerated. To simulate the supporting arch in tunnel engineering well, a new approach is proposed by improving the beam element. The yield criterion of the beam element subjected to compression-bending loads is established based on the now-available bearing capacity formulas of some typical compression-bending sections. In addition, the yield criterion is embedded in the FLAC^3D main program by using the FISH language, and the modification of the beam model and the yielding failure simulation of the supporting arch are finally implemented. Compression-bending tests and roadway tunnel arch support example analysis were performed. The results are as follows: (1) the modified model showed the dependence of the bending moment and axial force on the yielding action of the beam element under compression-bending loads; (2) the implementation program is effective and sensitive; (3) the computing deviation caused by the shortcomings of the original beam element model was effectively suppressed, the mechanical behavior and surrounding rock supporting laws exhibited by the arch model were much closer to reality, and the calculation accuracy and design reliability were improved by the new simulation approach.

Solid granules medium forming (SGMF), a new flexible die forming technology, uses solid granules instead of a rigid male or female die (or elastomer, liquid) for sheet metal drawing. The good fluidity and compressive capacity of a solid granules medium can improve the forming limit of complex shell parts. The sheet metal drawing process of SGMF is a compound process of drawing and bulging, which is very different from the conventional drawing process. A parabolic part is used as the research object for a study of the forming process. Two concepts, drawing weight and bulging weight, are originally proposed in the sheet metal drawing of SGMF (replacing the rigid male die), and the corresponding expressions are obtained. The computational formulas of geometrical conditions and strain in the sheet metal drawing of SGMF are established, and the radius of the strain dividing circle is obtained by calculation. The established theoretical model is applied to the research object, an aircraft part, to analyze the forming process. The results show that the proposed theory can be applied to analyze the strain in different deformation regions of SGMF. This original theory provides a new theoretical analysis for studying the sheet metal drawing of SGMF.

The effect of a gradual contraction pipe (GCP) on gas-liquid flow in a circular-sectioned horizontal to vertical 90° duct bend was investigated by computational fluid dynamics (CFD) simulation. The hydrodynamics of gas-liquid flow in 90° duct bends with and without a GCP in the vertical section were compared using a 3D steady Eulerian-Eulerian approach. The predicted static pressure in the vertical section of the pipes and the pressure drop in the whole pipe were consistent with experimental data. Results of simulations showed that liquid could distribute more uniformly at the exit of the pipe with a GCP. The increased uniformity was accompanied by an increase in pressure drop by a factor of less than 10% compared to the pipe without a GCP. The position of minimum pressure in the bend was changed by the GCP. A GCP can alter the trajectories of the fluid and secondary flow. As a result, the fluid can quickly reach a steady state downstream from the bend.

Oxidative dehydrogenation (ODH) of mono and mixed-butenes to 1,3-butadiene (BD) was conducted using individual and dual bed catalyst systems, consisting of ZnFe₂O₄, Co₉Fe₃Bi₁Mo₁₂O₅₁ or both. The dual bed catalyst system gave improved catalytic performance. A mechanism based on synergy between the catalysts is proposed to explain the improved overall butene conversion. The proportion of the reactants differed between the catalyst beds in the dual bed system, making better use of the catalytic activity of the second bed. The existence of all butene isomers inhibited isomerization, leading to a higher proportion of ODH reactions and thus improved the conversion of butene and the yield of BD. The packing sequences and the volume ratio of the catalysts in the bed were optimized. The results indicated that the sequence with ZnFe₂O₄ on top and a catalyst packing ratio of between 4:6 and 6:4 led to better activity.

Diversification in shopping, a long-pursued subject in consumer behavior analysis, is approached from a broad perspective of the diversity in daily travel patterns, which may or may not involve shopping trips, as well as the diversity in shopping locations and frequency. The focus of this analysis is on the heterogeneity across individuals in the ways in which they each diversify their respective shopping behavior. This study explores differences across individuals in the variations of their shopping travel patterns across days. Treating the day-of-the-week evolution of shopping travel patterns as a stochastic process, characteristics of diversification are quantified for respective individuals. Finally, heterogeneity across individuals is identified using an array of statistical methods. The analysis, based on results of a six-week travel diary survey in Germany with geo-coded activity locations, reveals the effects of individual, household, and urban attributes on diversification in shopping behavior, including that full-time workers with medium incomes (4000–4999 Deutsche Mark per month) tend to have more variations in their shopping engagement.