A kind of hybrid device for acoustic noise reduction and vibration energy harvesting based on the silicon micro- perforated panel （MPP） resonant structure is investigated in the article. The critical parts of the de...A kind of hybrid device for acoustic noise reduction and vibration energy harvesting based on the silicon micro- perforated panel （MPP） resonant structure is investigated in the article. The critical parts of the device include MPP and energy harvesting membranes. They are all fabricated by means of silicon micro-electro-mechanical systems （MEMS） tech- nology. The silicon MPP has dense and accurate micro-holes. This noise reduction structure has the advantages of wide band and higher absorption coefficients. The vibration energy harvesting part is formed by square piezoelectric membranes arranged in rows. ZnO material is used as it has a good compatibility with the fabrication process. The MPP, piezo- electric membranes, and metal bracket are assembled into a hybrid device with multifunctions. The device exhibits good performances of acoustic noise absorption and acoustic-electric conversion. Its maximum open circuit voltage achieves 69.41 mV.展开更多
This paper presents the development and performance of micro-perforated panels(MPP)from natural fiber reinforced composites.The MPP is made of Polylactic Acid(PLA)reinforced with Oil Palm Empty Fruit Bunch Fiber(OPEFB...This paper presents the development and performance of micro-perforated panels(MPP)from natural fiber reinforced composites.The MPP is made of Polylactic Acid(PLA)reinforced with Oil Palm Empty Fruit Bunch Fiber(OPEFBF).The investigation was made by varying the fiber density,air gap,and perforation ratio to observe the effect on the Sound Absorption Coefficient(SAC)through the experiment in an impedance tube.It is found that the peak level of SAC is not affected,but the peak frequency shifts to lower frequency when the fiber density is increased.This phenomenon might be due to the presence of porosity in the inner wall of the holes.Increasing or decreasing the air gap and perforation ratio shifts the peaks of acoustic absorption either way.展开更多
The geometric parameters of micro-perforated panels with irregular holes cannot be directly known,making it difficult to calculate the sound absorption performance.Therefore,we propose a method of estimating the geome...The geometric parameters of micro-perforated panels with irregular holes cannot be directly known,making it difficult to calculate the sound absorption performance.Therefore,we propose a method of estimating the geometric parameters of micro-perforated panels.The irregular holes are treated as equivalent circular ones,and the model of estimating the geometric parameters is established by using Maa's theory about the panel with circular holes.The result of the parameter estimation of a type of micro-perforated panel is used to predict the absorption performance,resulting in good agreement with experiments.According to the influences of the geometric parameters of the panel on the high absorption region,we discuss the relationship between the application limit of Maa's theory and the geometric parameters,and investigate the evolution law of the sound absorption performance when the panel is polluted by dust.If the parameters of the panel are designed near the center of the high absorption region,large value of the application limit of Maa's theory can be obtained;and if the parameters are located in the upper right part of the high absorption region,a certain degree of dust pollution of the panel does not decrease the sound absorption performance.展开更多
利用时域核磁共振(TD-NMR)技术,为研究人造板和水分的关系提供新方法.该文通过研究胶合板(Plywood)、刨花板(Particle board)、中密度纤维板(Medium Density Fiberboard)3种常用人造板吸水过程中水分的自由感应衰减(FID)信号的变化,得...利用时域核磁共振(TD-NMR)技术,为研究人造板和水分的关系提供新方法.该文通过研究胶合板(Plywood)、刨花板(Particle board)、中密度纤维板(Medium Density Fiberboard)3种常用人造板吸水过程中水分的自由感应衰减(FID)信号的变化,得出传统称重法得到的吸水率与吸水过程中测得的FID信号高度线性相关,24 h吸水率由大到小依次为胶合板>刨花板>中密度纤维板.通过3种人造板24 h吸水过程中自旋-自旋弛豫时间(T2)大小及分布的实验数据,分析了吸水过程中人造板中水分的状态.实验结果证实了TD-NMR是研究人造板与水分的关系的一个有效手段.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51305423)the National Basic Research Program of China(GrantNo.2011CB302104)
文摘A kind of hybrid device for acoustic noise reduction and vibration energy harvesting based on the silicon micro- perforated panel （MPP） resonant structure is investigated in the article. The critical parts of the device include MPP and energy harvesting membranes. They are all fabricated by means of silicon micro-electro-mechanical systems （MEMS） tech- nology. The silicon MPP has dense and accurate micro-holes. This noise reduction structure has the advantages of wide band and higher absorption coefficients. The vibration energy harvesting part is formed by square piezoelectric membranes arranged in rows. ZnO material is used as it has a good compatibility with the fabrication process. The MPP, piezo- electric membranes, and metal bracket are assembled into a hybrid device with multifunctions. The device exhibits good performances of acoustic noise absorption and acoustic-electric conversion. Its maximum open circuit voltage achieves 69.41 mV.
基金sponsored by Taylor’s University Flagship Research Grant TUFR/2017/001/05。
文摘This paper presents the development and performance of micro-perforated panels(MPP)from natural fiber reinforced composites.The MPP is made of Polylactic Acid(PLA)reinforced with Oil Palm Empty Fruit Bunch Fiber(OPEFBF).The investigation was made by varying the fiber density,air gap,and perforation ratio to observe the effect on the Sound Absorption Coefficient(SAC)through the experiment in an impedance tube.It is found that the peak level of SAC is not affected,but the peak frequency shifts to lower frequency when the fiber density is increased.This phenomenon might be due to the presence of porosity in the inner wall of the holes.Increasing or decreasing the air gap and perforation ratio shifts the peaks of acoustic absorption either way.
基金supported by the General Project of College Natural Science Research of Jiangsu Province(16KJD460002)the National Natural Science Foundation of China(51605209)
文摘The geometric parameters of micro-perforated panels with irregular holes cannot be directly known,making it difficult to calculate the sound absorption performance.Therefore,we propose a method of estimating the geometric parameters of micro-perforated panels.The irregular holes are treated as equivalent circular ones,and the model of estimating the geometric parameters is established by using Maa's theory about the panel with circular holes.The result of the parameter estimation of a type of micro-perforated panel is used to predict the absorption performance,resulting in good agreement with experiments.According to the influences of the geometric parameters of the panel on the high absorption region,we discuss the relationship between the application limit of Maa's theory and the geometric parameters,and investigate the evolution law of the sound absorption performance when the panel is polluted by dust.If the parameters of the panel are designed near the center of the high absorption region,large value of the application limit of Maa's theory can be obtained;and if the parameters are located in the upper right part of the high absorption region,a certain degree of dust pollution of the panel does not decrease the sound absorption performance.
