Efficient elastic wave focusing is crucial in materials and physical engineering.Elastic coding metasurfaces,which are innovative planar artificial structures,show great potential for use in the field of wave focusing...Efficient elastic wave focusing is crucial in materials and physical engineering.Elastic coding metasurfaces,which are innovative planar artificial structures,show great potential for use in the field of wave focusing.However,elastic coding lenses(ECLs)still suffer from low focusing performance,thickness comparable to wavelength,and frequency sensitivity.Here,we consider both the structural and material properties of the coding unit,thus realizing further compression of the thickness of the ECL.We chose the simplest ECL,which consists of only two encoding units.The coding unit 0 is a straight structure constructed using a carbon fiber reinforced composite material,and the coding unit 1 is a zigzag structure constructed using an aluminum material,and the thickness of the ECL constructed using them is only 1/8 of the wavelength.Based on the theoretical design,the arrangement of coding units is further optimized using genetic algorithms,which significantly improves the focusing performance of the lens at different focus and frequencies.This study provides a more effective way to control vibration and noise in advanced structures.展开更多
Electrorheological（ER） fluid is a type of smart fluid whose shear yield stress relies on the external electrical field strength. The transition of ER fluid microstructure driven by the electrical field is the reason...Electrorheological（ER） fluid is a type of smart fluid whose shear yield stress relies on the external electrical field strength. The transition of ER fluid microstructure driven by the electrical field is the reason why viscosity changes.Experimentally, the transparent electrodes are used to investigate the column size distribution where an external electric field is applied to a colloidal suspension, i.e., ER fluid is increased. The coarsening profile of ER suspensions is strongly related to electrical field strength, but it is insensitive to particle size. In addition, in a low field range the shear stress corresponding to the mean column diameter is studied and they are found to satisfy a power law. However, this dependence is invalid when the field strength surpasses a threshold value.展开更多
Dark photons have been well motivated as strong candidates for dark force carriers and light dark matter in the sub-GeV mass range.Compared with collider experiments,fixed-target experiments provide a complementary ap...Dark photons have been well motivated as strong candidates for dark force carriers and light dark matter in the sub-GeV mass range.Compared with collider experiments,fixed-target experiments provide a complementary approach to searching for dark photons,particularly in the lower mass range.We have studied the physics potential of the electron-on-target experiment based on the Shanghai SHINE facility,which provides 10 MHz single electron beam at 8 GeV energy.This analysis focuses on dark photons being produced via electron and nucleon interaction and then decays to dark matter candidates,which escape detection as missing momentum in the detector.This experiment takes advantage of using missing momentum to enhance signal versus background separation power.In this study,signal samples as a function of dark photon mass and an inclusive background sample with 2.5 billion events are simulated with GEANT4.For better background estimates,major rare background processes have also been simulated.This paper presents the experiment and detector design,signal and background simulations,analysis strategy,and the prospective study of the experiment sensitivity.With 9×10^(14) electron-on-target events(about three years running),this experiment is expected to rule out most of the sensitive regions predicted by popular dark photon models.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.12404531)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province,China(Grant No.23KJB140011)。
文摘Efficient elastic wave focusing is crucial in materials and physical engineering.Elastic coding metasurfaces,which are innovative planar artificial structures,show great potential for use in the field of wave focusing.However,elastic coding lenses(ECLs)still suffer from low focusing performance,thickness comparable to wavelength,and frequency sensitivity.Here,we consider both the structural and material properties of the coding unit,thus realizing further compression of the thickness of the ECL.We chose the simplest ECL,which consists of only two encoding units.The coding unit 0 is a straight structure constructed using a carbon fiber reinforced composite material,and the coding unit 1 is a zigzag structure constructed using an aluminum material,and the thickness of the ECL constructed using them is only 1/8 of the wavelength.Based on the theoretical design,the arrangement of coding units is further optimized using genetic algorithms,which significantly improves the focusing performance of the lens at different focus and frequencies.This study provides a more effective way to control vibration and noise in advanced structures.
基金supported by the National Natural Science Foundation of China(Grant Nos.11474345 and 11674043)
文摘Electrorheological（ER） fluid is a type of smart fluid whose shear yield stress relies on the external electrical field strength. The transition of ER fluid microstructure driven by the electrical field is the reason why viscosity changes.Experimentally, the transparent electrodes are used to investigate the column size distribution where an external electric field is applied to a colloidal suspension, i.e., ER fluid is increased. The coarsening profile of ER suspensions is strongly related to electrical field strength, but it is insensitive to particle size. In addition, in a low field range the shear stress corresponding to the mean column diameter is studied and they are found to satisfy a power law. However, this dependence is invalid when the field strength surpasses a threshold value.
基金supported by the National Natural Science Foundation of China(Grant No.12150006)Shanghai Pilot Program for Basic Research—Shanghai Jiao Tong University(Grant No.21TQ1400209)。
文摘Dark photons have been well motivated as strong candidates for dark force carriers and light dark matter in the sub-GeV mass range.Compared with collider experiments,fixed-target experiments provide a complementary approach to searching for dark photons,particularly in the lower mass range.We have studied the physics potential of the electron-on-target experiment based on the Shanghai SHINE facility,which provides 10 MHz single electron beam at 8 GeV energy.This analysis focuses on dark photons being produced via electron and nucleon interaction and then decays to dark matter candidates,which escape detection as missing momentum in the detector.This experiment takes advantage of using missing momentum to enhance signal versus background separation power.In this study,signal samples as a function of dark photon mass and an inclusive background sample with 2.5 billion events are simulated with GEANT4.For better background estimates,major rare background processes have also been simulated.This paper presents the experiment and detector design,signal and background simulations,analysis strategy,and the prospective study of the experiment sensitivity.With 9×10^(14) electron-on-target events(about three years running),this experiment is expected to rule out most of the sensitive regions predicted by popular dark photon models.
