摘要：The formations of desiccation cracks and their pattems in drying droplets of protein solutions are studied experimentally. The solvent evaporation causes the dehydration self-organization phenomenon in colloidal droplets, followed by the formations of desiccation cracks. Two categories of highly ordered crack patterns, which we name ＂daisy＂ and ＂wavy-ring＂, are identified in the drying droplets. We explore the shifting of crack patterns from the ＂daisy＂ to the ＂wavy-ring＂ by varying the concentration of protein droplets. The results show that the concentration correlates with the pattern of deposition film directly, and modulates the periodicity of the crack pattern. We investigate the formations and periodicities of these two kinds of crack patterns, and obtain the scaling law of periodicity of the ＂wavy-ring＂ crack pattern. The relationship between the deposition pattern and the highly ordered crack patterns is also examined. This study will help in understanding the formation mechanisms of crack patterns in drying droplets of protein solutions and assist the future design of crack patterns in practical applications.

摘要：The large-eddy simulation(LES)with the dynamic Smagorinsky model is used to predict the interior sound of an idealized vehicle cabin under the excitation of the wall pressures from turbulent channel *** comparison with direct numerical simulation(DNS),the LES results overpredict the sound pressure level(SPL)at low frequencies and underpredict the SPL at high *** incorrect predictions result from the incorrect prediction of LES on surface pressures,where the LES over-estimates the wavenumber and frequencies spectra of surface pressures at small wavenumbers and frequencies and under-estimates the spectra at large wavenumbers and ***,the LES results are close to the filtered-DNS results,implying that the unresolved scales are also important to surface pressures and interior *** Euler-Bernoulli beam under the excitation of exterior pressures,which serves as a simple model for aero-vibro-acoustics in the case of hydrodynamical fast,is used to explain the observed predictions and show that the Corcos model cannot represent the variation of turbulence pressure spectra at wavenumbers and ***,the new requirement for the LES method,when applied to fluid-structural-acoustic interaction problems at high Reynolds numbers,is the correct prediction of wavenumber and frequency spectra of turbulence wall pressure.

摘要：The significant increase in speed of high-speed train will cause the dynamic contact force of the pantograph-catenary system to fluctuate more severely,which poses a challenge to the study of the pantograph-catenary relationship and the design of highspeed *** pantograph-catenary coupling quality is the essential condition to ensure safe and efficient operation of high-speed train,stable and reliable current collection,and reduction in the wear of contact wires and pantograph contact *** them,the dynamic parameters of high-speed pantographs are crucial to pantograph-catenary coupling *** the reduction of the standard deviation of the pantograph-catenary contact force as the optimization goal,multi-parameter joint optimization designs for the high-speed pantograph with two contact strips at multiple running speeds are ***,combining the sensitivity analysis at the optimal solutions,with the parameters and characteristics of in-service DSA380 highspeed pantograph,the optimization proposal of DSA380 was given.

摘要：Responsive soft materials capable of complex,reversible,and rapid geometric deformations under external stimuli hold significant potential for applications in minimally invasive medicine,wearable devices,and soft *** this study,we present a novel approach for designing reconfigurable three dimensional(3D)deformable magnetic soft materials through photothermal *** embedding hard magnetic particles within a polymer matrix composed of fibrous polypyrrole(PPy)and semi-crystalline polymer,we develop magnetic composites that can be remotely controlled to achieve precise,programmable deformations under an external magnetic *** key innovation lies in utilizing the photothermal effect of PPy,which temporarily alters the viscosity of the composite when irradiated with infrared light,allowing dynamic orientation of the magnetic *** cooling,the magnetic anisotropy is solidified,enabling rapid and reversible geometric *** method allows for intricate control over the magnetization distribution,leading to the development of multifunctional devices with various potential applications such as complex 3D deformations for soft robotics,multimodal electrical switches,rewritable quick response codes,and shape-adaptable *** study not only enhances the understanding of magnetic moment programming in soft materials but also opens new avenues for the design of adaptive and responsive materials for advanced technological applications.