This study proposes a micro vibration mitigation system using viscous dampers to solve the problem of vibration in a high-tech building. Due to the operating frequency of the air conditioners and fundamental mode of t...This study proposes a micro vibration mitigation system using viscous dampers to solve the problem of vibration in a high-tech building. Due to the operating frequency of the air conditioners and fundamental mode of the floors, a resonant phenomenon is occasionally experienced at the upper levels of the structure. Several strategies were considered, and viscous dampers combined with a suspension system were chosen to mitigate this annoying situation. A theoretical analysis was first executed to determine the optimal design value of the damper and the suspension spring. An efficient reduction in floor velocity of approximately 50 % was achieved by the proposed system. Practical verifications including a performance test of the micro-vibration-oriented dampers, the pragmatic application result, and a comparison in one-third octave spectrum was then carried out. The performance of the system was demonstrated by the data measured. It alleviated more trembling than was numerically expected. The energy absorbed by the viscous dampers is illustrated by the hysteresis loops and the one-third octave spectrum. It is found that with the proposed system, the vibration can be effectively captured by the viscous damper and converted to lower frequency-content tremors. The success of this project greatly supports the proposed standard two-stage analysis procedure for mitigating micro-vibration problems in practice. This research extends the use of viscous dampers to a new field.展开更多
Purpose: The purpose of this study was to investigate the effects of Micro Vibrational therapy (MVT) on muscle stiffness and blood flow in the skin before and after Micro Vibrational therapy in healthy subjects in ord...Purpose: The purpose of this study was to investigate the effects of Micro Vibrational therapy (MVT) on muscle stiffness and blood flow in the skin before and after Micro Vibrational therapy in healthy subjects in order to scientifically verify the effects of MVT. Methods: Micro Vibrational therapy is nurse care use in Japan. It was performed on the backs of 30 subjects (8 males and 22 females) in their 20 s to 50 s according to the eligibility criteria. The resting state before implementation was set as the baseline for the control group, and after 30 seconds of MVT was set as the intervention group. The effects of the MVT were statistically analyzed by these factors and subjective sensation by Visual Analog Scale. Results: The muscle hardness of the area where the MVT was applied for 30 seconds decreased to 29.54 (SD 5.04) after the application, compared to 30.45 (SD 5.05) before. A corresponding t-test showed a significant difference (p = 0.019). Skin blood flow increased from a median of 0.76 (variance 0.062) before to a median of 0.86 (variance 0.16) after the procedure. The Wilcoxon rank test showed a significant difference (p = 0.000). Circulatory response was confirmed by SBP, DBP, and HR. SBP of 108.6 mmHg (SD 14.8) before the study decreased to 105.7 mmHg (SD 15.0) after the study, and DBP of 65.6 mmHg (SD 11.1) before the study decreased to 62.7 mmHg (SD 11.8) after the study. HR decreased from 71.6 beats per minute (SD 10.3) before to 69.2 beats per minute (SD 11.7) after. There was a significant difference in all cardiovascular indices (p < 0.05). VAS (pain, stiffness, and fatigue) was significantly decreased after MVT (p < 0.05). Conclusion: Micro Vibrational therapy tended to decrease muscle hardness and increase skin blood flow even in the short time of 30 seconds. The results suggest that local vibration stimulation is not likely to cause a sudden increase in blood pressure or pulse rate fluctuation. These results suggest that hand vibration nursing care may be applicable to acute patients with unstable circulatory conditions.展开更多
Dear Editor,This letter proposes a novel dynamic vision-enabled intelligent micro-vibration estimation method with spatiotemporal pattern consistency.Inspired by biological vision,dynamic vision data are collected by ...Dear Editor,This letter proposes a novel dynamic vision-enabled intelligent micro-vibration estimation method with spatiotemporal pattern consistency.Inspired by biological vision,dynamic vision data are collected by the event camera,which is able to capture the micro-vibration information of mechanical equipment,due to the significant advantage of extremely high temporal sampling frequency.展开更多
When a satellite is in orbit, its flywheel will generate micro vibration and affect the imaging quality of the camera. In order to reduce this effect, a rubber shock absorber is used, and a numerical model and an expe...When a satellite is in orbit, its flywheel will generate micro vibration and affect the imaging quality of the camera. In order to reduce this effect, a rubber shock absorber is used, and a numerical model and an experimental setup are developed to investigate its effect on the micro vibration in the study. An integrated model is developed for the system, and a ray tracing method is used in the modeling. The spot coordinates and displacements of the image plane are obtained, and the modulate transfer function （MTF） of the system is calculated. A satellite including a rubber shock absorber is designed, and the experiments are carried out. Both simulation and experiments results show that the MTF increases almost 10 %, suggesting the rubber shock absorber is useful to decrease the flywheel vibration.展开更多
This work investigates the evolution of structure and mechanical performance of metallic glasses（MGs）under a proposed rapid forming approach. Through the unique ultrasonic-assisted micro injection method, micro MGs ...This work investigates the evolution of structure and mechanical performance of metallic glasses（MGs）under a proposed rapid forming approach. Through the unique ultrasonic-assisted micro injection method, micro MGs parts with fine dimensional accuracy were successfully fabricated. The temperature during the micro injection is higher than the glass transition temperature and lower than the crystallization temperature. Differential scanning calorimeter curve and X-ray diffraction pattern show that the MGs micro parts keep the amorphous nature after the ultrasonic-assisted micro injection. Our results propose a novel route for the fast forming of MGs and have promising applications in the rapid fabrication of micro scale products and devices.展开更多
The relation of mass, stiffness and rate of damping is obtained by using the mechanical analysis of the obstructive vibration system of two dimensions for the design of the obstructive vibration system of more freedom...The relation of mass, stiffness and rate of damping is obtained by using the mechanical analysis of the obstructive vibration system of two dimensions for the design of the obstructive vibration system of more freedom and the micro vibration test bed. The result of stimulational experiment indicates that the isolation of vibration of this system is satisfactory. The design method of vibration can be used as the reference to ultra precision machine tool, super micro orientation machanism and so on.展开更多
Various hydrogels have been explored to create minimally invasive microneedles(MNs)to extract interstitial fluid(ISF).However,current methods are time-consuming and typically require 10–15 min to extract 3–5 mg of I...Various hydrogels have been explored to create minimally invasive microneedles(MNs)to extract interstitial fluid(ISF).However,current methods are time-consuming and typically require 10–15 min to extract 3–5 mg of ISF.This study introduces two spiral-shaped swellable MN arrays:one made of gelatin methacryloyl(GelMA)and polyvinyl alcohol(PVA),and the other incorporating a combination of PVA,polyvinylpyrrolidone(PVP),and hyaluronic acid(HA)for fast ISF extraction.These MN arrays demonstrated a rapid swelling ratio of 560±79.6%and 370±34.1%in artificial ISF within 10 min,respectively.Additionally,this study proposes a novel method that combines MNs with a custom-designed Arduino-based applicator vibrating at frequency ranges(50–100 Hz)to improve skin penetration efficiency,thereby enhancing the uptake of ISF in ex vivo.This dynamic combination enables GelMA/PVA MNs to rapidly uptake 6.41±1.01 mg of ISF in just 5 min,while PVA/PVP/HA MNs extract 5.38±0.77 mg of ISF within the same timeframe.To validate the capability of the MNs to recover glucose as the target biomarker,a mild heating procedure is used,followed by determining glucose concentration using a D-glucose content assay kit.The efficient extraction of ISF and glucose detection capabilities of the spiral MNs suggest their potential for rapid and minimally invasive biomarker sensing.展开更多
In the natural world,leaf-cutting ants cause vibrations through their mutual scraping of file-scraper organs.In this study,we designed a Biomimetic Ultrasonic Exciter(BUE)that imitates leaf-cutting ants.The operating ...In the natural world,leaf-cutting ants cause vibrations through their mutual scraping of file-scraper organs.In this study,we designed a Biomimetic Ultrasonic Exciter(BUE)that imitates leaf-cutting ants.The operating characteristics of the BUE were studied through experimental testing and finite element simulations.The results showed that the BUE could generate stable ultrasonic vibrations,and that the excitation frequency only needed to be half the Output Frequency(OF).This frequency-doubling phenomenon was conducive to achieving BUE miniaturization.To further explore the phenomenon of frequency-doubling vibration output,this study designed scrapers of five different sizes,conducted excitation and first-order natural frequency measurement tests,and the corresponding finite element simulations.It was found that each scraper could operate in frequency-doubling mode,but the operating frequency and natural mode frequencies did not correspond with one another.To further explicate experimental and simulation results,a two-degrees-of-freedom vibration model was developed.It was evident that the contact relationship between the dentate disc and scraper introduced strong nonlinear factors into the system,accounting for the frequency-doubling phenomenon and the difference between the BUE’s operating and mode frequencies.The BUE could be expected to facilitate the production of high-power micro-ultrasonic generators and has potential application value in the fields of mechanical processing,industrial production,and medical health.展开更多
Although the performance of space cameras has largely improved, the micro vibration from flywheel disturbances still significantly affects the image quality of these cameras. This study adopted a passive isolation met...Although the performance of space cameras has largely improved, the micro vibration from flywheel disturbances still significantly affects the image quality of these cameras. This study adopted a passive isolation method to reduce the negative effect of flywheel disturbance on image quality. A metal-rubber shock absorber was designed and installed in a real satellite. A finite element model of an entire satellite was constructed, and a transient analysis was conducted afterward. The change in the modulate transfer function was detected using ray tracing and optical transfer function formulas. Experiments based on real products were performed to validate the influence of the metal-rubber shock absorber. The experimental results confirmed the simulation results by showing that the negative effects of flywheel dis- turbance on the image quality of space cameras can be diminished significantly using the vibration isolation method.展开更多
文摘This study proposes a micro vibration mitigation system using viscous dampers to solve the problem of vibration in a high-tech building. Due to the operating frequency of the air conditioners and fundamental mode of the floors, a resonant phenomenon is occasionally experienced at the upper levels of the structure. Several strategies were considered, and viscous dampers combined with a suspension system were chosen to mitigate this annoying situation. A theoretical analysis was first executed to determine the optimal design value of the damper and the suspension spring. An efficient reduction in floor velocity of approximately 50 % was achieved by the proposed system. Practical verifications including a performance test of the micro-vibration-oriented dampers, the pragmatic application result, and a comparison in one-third octave spectrum was then carried out. The performance of the system was demonstrated by the data measured. It alleviated more trembling than was numerically expected. The energy absorbed by the viscous dampers is illustrated by the hysteresis loops and the one-third octave spectrum. It is found that with the proposed system, the vibration can be effectively captured by the viscous damper and converted to lower frequency-content tremors. The success of this project greatly supports the proposed standard two-stage analysis procedure for mitigating micro-vibration problems in practice. This research extends the use of viscous dampers to a new field.
文摘Purpose: The purpose of this study was to investigate the effects of Micro Vibrational therapy (MVT) on muscle stiffness and blood flow in the skin before and after Micro Vibrational therapy in healthy subjects in order to scientifically verify the effects of MVT. Methods: Micro Vibrational therapy is nurse care use in Japan. It was performed on the backs of 30 subjects (8 males and 22 females) in their 20 s to 50 s according to the eligibility criteria. The resting state before implementation was set as the baseline for the control group, and after 30 seconds of MVT was set as the intervention group. The effects of the MVT were statistically analyzed by these factors and subjective sensation by Visual Analog Scale. Results: The muscle hardness of the area where the MVT was applied for 30 seconds decreased to 29.54 (SD 5.04) after the application, compared to 30.45 (SD 5.05) before. A corresponding t-test showed a significant difference (p = 0.019). Skin blood flow increased from a median of 0.76 (variance 0.062) before to a median of 0.86 (variance 0.16) after the procedure. The Wilcoxon rank test showed a significant difference (p = 0.000). Circulatory response was confirmed by SBP, DBP, and HR. SBP of 108.6 mmHg (SD 14.8) before the study decreased to 105.7 mmHg (SD 15.0) after the study, and DBP of 65.6 mmHg (SD 11.1) before the study decreased to 62.7 mmHg (SD 11.8) after the study. HR decreased from 71.6 beats per minute (SD 10.3) before to 69.2 beats per minute (SD 11.7) after. There was a significant difference in all cardiovascular indices (p < 0.05). VAS (pain, stiffness, and fatigue) was significantly decreased after MVT (p < 0.05). Conclusion: Micro Vibrational therapy tended to decrease muscle hardness and increase skin blood flow even in the short time of 30 seconds. The results suggest that local vibration stimulation is not likely to cause a sudden increase in blood pressure or pulse rate fluctuation. These results suggest that hand vibration nursing care may be applicable to acute patients with unstable circulatory conditions.
文摘Dear Editor,This letter proposes a novel dynamic vision-enabled intelligent micro-vibration estimation method with spatiotemporal pattern consistency.Inspired by biological vision,dynamic vision data are collected by the event camera,which is able to capture the micro-vibration information of mechanical equipment,due to the significant advantage of extremely high temporal sampling frequency.
文摘When a satellite is in orbit, its flywheel will generate micro vibration and affect the imaging quality of the camera. In order to reduce this effect, a rubber shock absorber is used, and a numerical model and an experimental setup are developed to investigate its effect on the micro vibration in the study. An integrated model is developed for the system, and a ray tracing method is used in the modeling. The spot coordinates and displacements of the image plane are obtained, and the modulate transfer function （MTF） of the system is calculated. A satellite including a rubber shock absorber is designed, and the experiments are carried out. Both simulation and experiments results show that the MTF increases almost 10 %, suggesting the rubber shock absorber is useful to decrease the flywheel vibration.
基金supported by the National Natural Science Foundation of China (Nos. 51605304, 51575360, 51375315 and 51405306)the China Postdoctoral Science Foundation (No. 2016M601423)+2 种基金the Ph.D. Start-up Fund of Natural Science Foundation of Guangdong Province (Nos. 2016A030310036 and 2016A030310043)the Major Science and Technology Project of Guangdong Province (No. 2014B010131006)the Science and Technology Innovation Commission of Shenzhen (Nos. JCYJ20150525092941026, JCYJ20150625102923775, JCYJ20140418095735629 and JSGG20140519104809878)
文摘This work investigates the evolution of structure and mechanical performance of metallic glasses（MGs）under a proposed rapid forming approach. Through the unique ultrasonic-assisted micro injection method, micro MGs parts with fine dimensional accuracy were successfully fabricated. The temperature during the micro injection is higher than the glass transition temperature and lower than the crystallization temperature. Differential scanning calorimeter curve and X-ray diffraction pattern show that the MGs micro parts keep the amorphous nature after the ultrasonic-assisted micro injection. Our results propose a novel route for the fast forming of MGs and have promising applications in the rapid fabrication of micro scale products and devices.
文摘The relation of mass, stiffness and rate of damping is obtained by using the mechanical analysis of the obstructive vibration system of two dimensions for the design of the obstructive vibration system of more freedom and the micro vibration test bed. The result of stimulational experiment indicates that the isolation of vibration of this system is satisfactory. The design method of vibration can be used as the reference to ultra precision machine tool, super micro orientation machanism and so on.
文摘Various hydrogels have been explored to create minimally invasive microneedles(MNs)to extract interstitial fluid(ISF).However,current methods are time-consuming and typically require 10–15 min to extract 3–5 mg of ISF.This study introduces two spiral-shaped swellable MN arrays:one made of gelatin methacryloyl(GelMA)and polyvinyl alcohol(PVA),and the other incorporating a combination of PVA,polyvinylpyrrolidone(PVP),and hyaluronic acid(HA)for fast ISF extraction.These MN arrays demonstrated a rapid swelling ratio of 560±79.6%and 370±34.1%in artificial ISF within 10 min,respectively.Additionally,this study proposes a novel method that combines MNs with a custom-designed Arduino-based applicator vibrating at frequency ranges(50–100 Hz)to improve skin penetration efficiency,thereby enhancing the uptake of ISF in ex vivo.This dynamic combination enables GelMA/PVA MNs to rapidly uptake 6.41±1.01 mg of ISF in just 5 min,while PVA/PVP/HA MNs extract 5.38±0.77 mg of ISF within the same timeframe.To validate the capability of the MNs to recover glucose as the target biomarker,a mild heating procedure is used,followed by determining glucose concentration using a D-glucose content assay kit.The efficient extraction of ISF and glucose detection capabilities of the spiral MNs suggest their potential for rapid and minimally invasive biomarker sensing.
基金supported by the National Natural Science Foundation of China(grant nos.91960203,51975035)。
文摘In the natural world,leaf-cutting ants cause vibrations through their mutual scraping of file-scraper organs.In this study,we designed a Biomimetic Ultrasonic Exciter(BUE)that imitates leaf-cutting ants.The operating characteristics of the BUE were studied through experimental testing and finite element simulations.The results showed that the BUE could generate stable ultrasonic vibrations,and that the excitation frequency only needed to be half the Output Frequency(OF).This frequency-doubling phenomenon was conducive to achieving BUE miniaturization.To further explore the phenomenon of frequency-doubling vibration output,this study designed scrapers of five different sizes,conducted excitation and first-order natural frequency measurement tests,and the corresponding finite element simulations.It was found that each scraper could operate in frequency-doubling mode,but the operating frequency and natural mode frequencies did not correspond with one another.To further explicate experimental and simulation results,a two-degrees-of-freedom vibration model was developed.It was evident that the contact relationship between the dentate disc and scraper introduced strong nonlinear factors into the system,accounting for the frequency-doubling phenomenon and the difference between the BUE’s operating and mode frequencies.The BUE could be expected to facilitate the production of high-power micro-ultrasonic generators and has potential application value in the fields of mechanical processing,industrial production,and medical health.
文摘Although the performance of space cameras has largely improved, the micro vibration from flywheel disturbances still significantly affects the image quality of these cameras. This study adopted a passive isolation method to reduce the negative effect of flywheel disturbance on image quality. A metal-rubber shock absorber was designed and installed in a real satellite. A finite element model of an entire satellite was constructed, and a transient analysis was conducted afterward. The change in the modulate transfer function was detected using ray tracing and optical transfer function formulas. Experiments based on real products were performed to validate the influence of the metal-rubber shock absorber. The experimental results confirmed the simulation results by showing that the negative effects of flywheel dis- turbance on the image quality of space cameras can be diminished significantly using the vibration isolation method.
