Piecewise linear blade twist is studied as a method for reducing the rotor vibratory loads.A rotor model based on an elastic beam concept is used to predict the loads.A four-bladed rotor with a shape similar to the UH...Piecewise linear blade twist is studied as a method for reducing the rotor vibratory loads.A rotor model based on an elastic beam concept is used to predict the loads.A four-bladed rotor with a shape similar to the UH-60 rotor is used as a baseline for comparisons.The blade is divided into three segments,which are inner,middle and outer segments respectively.Effect of the twist at different segments on the loads is discussed.The twists at all the segments can reduce the 4/rev(revolution)vertical hub force at low speeds.The 4/rev force can be reduced by 99.5%with a-24°/R(R is the blade radius)twist at the middle segment at 80 km/h.The twist at the inner segment is not helpful for reducing the 4/rev rolling and pitching moments,while the twists at other segments can control both the moments at most speeds.A parameter sweep is conducted to minimize these loads.To reduce the 4/rev force,all the segments need to be twisted at low speeds,while untwisted blades perform better at high speeds.For controlling the 4/rev moments,the outer segment should be highly twisted at low speeds,while high twists at the middle segment are essential at medium to high speeds.展开更多
Vibratory synchronization transmission (VST) is a kind of special physicalphenomenon in inertia vibration mechanical systems. For an inertia vibration mechanical systemdriven by one pair of motors runs in step, even t...Vibratory synchronization transmission (VST) is a kind of special physicalphenomenon in inertia vibration mechanical systems. For an inertia vibration mechanical systemdriven by one pair of motors runs in step, even the power supply of one motor is cut off, the motorcan continue to keep rotating state under the vibration exciting of the machine body driven by onlyone other motor. And its rotating frequency will be the same as that of the other one. The transientprocess of this wonderful physical phenomenon has not been described quantitatively according tocurrent-existing mechanical models. On the basis of investigation of the engineering characteristicsof VST, a mechanical and electrical coupling mathematical model of a two-shaft inertia vibrationmachine is established. With this model, the transient process of VST is recurred quantitatively andsuccessfully, and a reasonable explanation is given.展开更多
Mechanical Quality factor（Q factor） of the resonator is an important parameter for the cylinder vibratory gyroscope（CVG）. Traditional analytical methods mainly focus on a partial energy loss during the vibration p...Mechanical Quality factor（Q factor） of the resonator is an important parameter for the cylinder vibratory gyroscope（CVG）. Traditional analytical methods mainly focus on a partial energy loss during the vibration process of the CVG resonator, thus are not accurate for the mechanical Q factor prediction. Therefore an integrated model including air damping loss, surface defect loss, support loss, thermoelastic damping loss and internal friction loss is proposed to obtain the mechanical Q factor of the CVG resonator. Based on structural dynamics and energy dissipation analysis, the contribution of each energy loss to the total mechanical Q factor is quantificationally analyzed. For the resonator with radius ranging from 10 mm to 20 mm, its mechanical Q factor is mainly related to the support loss, thermoelastic damping loss and internal friction loss, which are fundamentally determined by the geometric sizes and material properties of the resonator. In addition, resonators made of alloy 3J53 （Ni42CrTiA1）, with different sizes, were experimentally fabricated to test the mechanical Q factor. The theoretical model is well verified by the experimental data, thus provides an effective theoretical method to design and predict the mechanical Q factor of the CVG resonator.展开更多
The vibratory roller is a piece of vital construction machinery in the field of road construction.The unmanned vibratory roller efficiently utilizes the automated driving technology in the vehicle engineering field,wh...The vibratory roller is a piece of vital construction machinery in the field of road construction.The unmanned vibratory roller efficiently utilizes the automated driving technology in the vehicle engineering field,which is innovative for the unmanned road construction.This paper develops and implements the autonomous construction system for the unmanned vibratory roller.Not only does the roller have the function of remote-controlled driving,but it also has the capability of autonomous road construction.The overall system design uses the Programmable Logic Controller(PLC)as the kernel controller.It establishes the communication network through multiple Input/Output(I/O)modules,Recommended Standard 232(RS232)serial port,Controller Area Network(CAN)bus,and wireless networks to control the roller vehicle completely.The locating information is obtained through the Global Navigation Satellite System(GNSS)satellite navigation equipment group to support the process of autonomous construction.According to the experimental results,the autonomous construction system can finally enable the roller to perform driving operations and construction independently,which was a significant step forward in engineering application.展开更多
In order to evaluate the performance of semi-active cab’s hydraulic mounts(SHM)of the off-road vibratory roller with the optimal fuzzy-PID(proportional integral derivative)control,a nonlinear dynamic model of the veh...In order to evaluate the performance of semi-active cab’s hydraulic mounts(SHM)of the off-road vibratory roller with the optimal fuzzy-PID(proportional integral derivative)control,a nonlinear dynamic model of the vehicle interacting with off-road terrains is established based on Matlab/Simulink software.The weighted root-mean-square(RMS)acceleration responses of the driver’s seat heave and the cab’s pitch angle are chosen as objective functions.The SHM is then optimized and analyzed via the optimal fuzzy-PID control under different operation conditions.The simulations results show that the driver’s ride comfort and the cab shaking are greatly affected by the off-road terrains under various operating conditions of the vehicle,especially at the speed from 8 to 12 km/h on a very poor terrain surface of Grenville soil ground under the vehicle travelling.With SHM using the optimal fuzzy-PID control,the driver’s ride comfort and the cab shaking are clearly improved under various operation conditions of the vehicle,particularly at the speed from 6 to 7 km/h of the vehicle traveling.展开更多
The effect of vibratory stress relief （VSR） is usually evaluated with the indirect method of observing the change of amplitude frequency response characteristics of structures. A new kind of evaluating method of VSR...The effect of vibratory stress relief （VSR） is usually evaluated with the indirect method of observing the change of amplitude frequency response characteristics of structures. A new kind of evaluating method of VSR based on the ultrasonic time-of-arrival method （UTM）, which can obtain the residual stress directly through measuring the propagation time of ultrasonic wave in the material, is presented. At first, the principle of the measuring method of residual stress based on UTM is analyzed. Then the measuring system of the method is described, which is in virtue of ultrasonic flaw detector and high-sampling-rate digital oscillograph. And a set of calibration system that contains a piece of standard specimen is also introduced. Experimental results prove the relation between the residual stress and the propagation time of ultrasonic in workpieces. Finally, the measuring and calibration systems are applied in evaluating the effect of VSR. The final test results show that the method is effective.展开更多
The Hong Kong–Zhuhai–Macao Bridge(HZMB)involved the installation of 120 mega-cylinders with a diameter of 22 m,weights up to 513 t,and penetration depths up to 33 m using an eight-vibratory hammer group.Due to the l...The Hong Kong–Zhuhai–Macao Bridge(HZMB)involved the installation of 120 mega-cylinders with a diameter of 22 m,weights up to 513 t,and penetration depths up to 33 m using an eight-vibratory hammer group.Due to the lack of engineering experience on the drivability of large-diameter cylinders under multiple vibratory hammers,predicting the penetration rate and time of steel cylinders is an open challenge that has a considerable impact on the construction control of the HZMB.In this study,the vibratory penetration of large-diameter steel cylinders in the HZMB is investigated based on geological surveys,field monitoring,and drivability analysis.The vibratory penetration rate,installation accuracy,and dynamic responses of the steel cylinders at both the eastern and western artificial islands are analyzed.The dynamic soil resistance has a great influence on the cylinder drivability.However,the current design methods for estimating the vibratory driving soil resistance are proven inaccurate without considering the scale effects.Therefore,a modified method with a normalized effective area ratio A_(r,eff)is proposed in this study to calculate the vibratory soil resistance for open-ended thin-wall cylinders under unplugged conditions.Considering the scale effects on the vibratory driving soil resistance,the proposed method leads to closer results to the measured data,providing a reference for future engineering practice.展开更多
The linear and nonlinear dynamic responses of a vibratory ring gyroscope are investigated in this study focusing on the response mechanism of such a vibratory gyroscope. It is found that the nonlinear equations govern...The linear and nonlinear dynamic responses of a vibratory ring gyroscope are investigated in this study focusing on the response mechanism of such a vibratory gyroscope. It is found that the nonlinear equations governing the drive and sense directions are coupled through both inertial linear and geometric nonlinear terms. Nonlinear responses are studied based on the full coupled nonlinear dynamic equations. The varying amplitude on the sense direction is analyzed for different input angular rates. The effect of nonlinearity on the ring gyroscope system is performed by comparing the results of nonlinear responses to those of linear responses. The contributions of some parameters to the amplitude responses and gyroscope sensitivity are analyzed, the conclusions of which provide guidelines to improve the sensitivity of the vibratory ring gyroscopes.展开更多
Micro-electro-mechanical system(MEMS)gyroscopes are an important sort of inertial sensor for identifying parameters of spinning structures,such as the spinning speed and angular deviation,based on the Coriolis effect....Micro-electro-mechanical system(MEMS)gyroscopes are an important sort of inertial sensor for identifying parameters of spinning structures,such as the spinning speed and angular deviation,based on the Coriolis effect.In this paper,the nonlinear mechanism of MEMS vibratory ring gyroscopes is analyzed by applying a fully coupled nonlinear model,in which the gyroscopic coupling and geometrically and structurally nonlinear couplings are all taken into account.The coupled differential equations governing the drive and sense motions are established via the Lagrangian equations.Numerical simulation is conducted,and the key nonlinear components and energy transfer behaviors between the drive and sense modes are elucidated.It is revealed that the cubic rigidity nonlinearity is another significant factor leading to the coupling between the drive and sense modes other than the gyroscopic coupling.Perturbation analysis is also carried out by using the method of multiple scales.The nonlinear frequency-amplitude responses of the drive and sense vibrations are obtained,and comprehensive parametric studies are performed.The significant effects of system damping,excitation amplitude,drive amplitude and spinning speed on the responses are discussed,which will facilitate to improve the nonlinear performance and sensitivity of the gyroscope.展开更多
Factors directly affecting the extraction rate of the piles pulled out by a vibratory pulling system are summarized and classified into five categories(excitation force,resistance,vibration amplitude,pile plumbness ke...Factors directly affecting the extraction rate of the piles pulled out by a vibratory pulling system are summarized and classified into five categories(excitation force,resistance,vibration amplitude,pile plumbness keeping,and slowing down at the later stage) from the mechanics and engineering practice.Field tests on steel sheet piles extracted by vibratory technique in different soil conditions are conducted to ascertain how these factors affect the extraction rate of a pile with regard to three major actors of vibratory pile pulling:the pile to be extracted,the selected pulling system,and the imposed soil conditions.The extraction rates of three different sheet pile types(having up to four different lengths) pulled out by two different vibratory pulling systems are documented.The piles with different lengths and types,pulled out with or without a clutch,have different extraction rates.The working parameters governing the vibratory hammer,such as excitation force and vibration amplitude,exert significant influences on the rate of pile extraction,especially in the early stages of up-lift process.The extraction rate of the piles driven in different soil conditions is uniform because different extraction resistances mainly refer to shaft friction.The properties of the pile-soil interface influence the extraction rate of the piles,and the extraction rate decreases with the time for which the piles have been buried in the earth.展开更多
Based on the working principle of vibratory excavation of hydraulic excavator,the expression of digging resistance changed with time under sine wave inspiritment was deduced;a comparison analysis was given after calcu...Based on the working principle of vibratory excavation of hydraulic excavator,the expression of digging resistance changed with time under sine wave inspiritment was deduced;a comparison analysis was given after calculating the forces status of rock and soil under static load and vibratory load respectively by using MATLAB;and then RFPA-2D(rock failure process analysis code)was used to make comparison of simulation experiment on rock and soil failure process under static load and vibratory load.The results demonstrate that,compared with the normal excavation under the same situation,the digging resistance and the energy consumption can be reduced by respectively 30%and 60%at maximum,and that the working efficiency can be increased by 45%at maximum owing to vibratory excavation.展开更多
Based on the advantages of hydraulic and pneumatic mounts,a new hydro-pneumatic mount(HPM)is proposed to improve the low-frequency ride comfort of vibration rollers.Through the experiment of the vibratory roller,a non...Based on the advantages of hydraulic and pneumatic mounts,a new hydro-pneumatic mount(HPM)is proposed to improve the low-frequency ride comfort of vibration rollers.Through the experiment of the vibratory roller,a nonlinear vehicle dynamic model working on off-road soil grounds is then established to assess the HPM's ride comfort in the low-frequency region.Two indices,the power spectral density(PSD)acceleration and root mean square(RMS)acceleration of the operator vibration and cab shaking,are chosen as objective functions in both the frequency and time regions.The research results show that when the cab isolations are equipped with the HPM,the RMS values of the operator's seat,cab's pitch and roll angles are reduced by 35%,42%and 53%;and the maximum PSD of the operator's seat,cab's pitch and roll angles are decreased by 39%,59%and 65%,respectively.Consequently,the characteristics of the nonlinear damper and high-static stiffness of HPM can greatly reduce the operator vibration and cab shaking in the low-frequency region when compared to the vibratory roller's cab using the rubber mounts.展开更多
Vibratory stimulation but also motor imagery and action observation can induce corticomotor modulation, as a bottom-up stimulus and top-down stimuli, respectively. However, it remains unknown whether the combination o...Vibratory stimulation but also motor imagery and action observation can induce corticomotor modulation, as a bottom-up stimulus and top-down stimuli, respectively. However, it remains unknown whether the combination of motor imagery, action observation, and vibratory stimulation can effectively increase corticomotor excitability. This study aimed to investigate the effect of motor imagery and/or action observation, in the presence or absence of vibratory stimulation, on the corticomotor excitability of healthy young adults. Vibratory stimulation was provided to the palm of the right hand. Action observation consisted in viewing a movie of someone else’s finger flexion and extension movements. The imagery condition required the participants to imagine they were moving their fingers while viewing the movie and attempting to move their fingers in accordance with the movie. Eleven right-handed healthy young adults were asked to perform six conditions randomly: 1) vibratory stimulation, imagery, and action observation, 2) vibratory stimulation and action observation, 3) vibratory stimulation and viewing of a blank screen, 4) imagery and action observation, 5) action observation, and 6) viewing of a blank screen. Single-pulse transcranial magnetic stimulation was conducted to assess corticomotor excitability and the peak-to-peak amplitude of the motor evoked potentials. The results showed that vibratory stimulation increases corticospinal excitability. The findings further revealed that performing motor imagery while viewing finger movement is more effective at inducing an augmentation of corticomotor excitability compared to action observation alone. Thus, the combination of motor imagery, action observation, and vibratory stimulation can effectively augment corticomotor excitability.展开更多
Computer programming-based numerical programs are firmly established in geotechnical engineering,with rapid growth of finite element modeling and machine learning techniques gaining much attention both in practice and...Computer programming-based numerical programs are firmly established in geotechnical engineering,with rapid growth of finite element modeling and machine learning techniques gaining much attention both in practice and academia.This study is intended to expedite the dissemination of advanced computer applications in terms of finite element simulation and machine learning models by investigating the dynamic response of geomaterials subjected to vibratory loads.Several trial models were built to perform the experimental investigations with a vibratory shaker,signal generator,several accelerometers,a data collection system,and other ancillary devices.The implicit integration techniques in commercialized software were adopted for numerical simulations.After data collection from numerical simulation,models were chosen,trained,and assessed to produce predictions that were then used in this study.Several technologies,including the ensemble boosted tree,squared exponential Gaussian Process Regression(GPR),Matern 5/2 GPR,exponential GPR,and decision tree architectures(fine and medium),were used to forecast the displacement of confined geomaterial.The displacement-depth ratio was found rising to 80%in the frequency range of 5 to 25 Hz,suggesting a considerable change in the behavior of the geomaterial.The Matern 5/2 GPR model showed better accuracy with an R2 value of 0.99,indicating an outstanding predictive ability.The Matern 5/2 GPR and boosted tree models could help better understand the links between displacement and its distribution along the direction of load application.The outcomes of this study based on computer-aided finite element programs can be effectively implemented in machine learning to develop computer programs.In conclusion,the computational machine learning models adopted in this study offer a new insight for uncovering hidden intrinsic laws and creating new knowledge for geotechnical researchers and practitioners.展开更多
Background Vibrotactile feedback systems are widely used in assistive technology,wearable devices,and virtual environments to deliver precise tactile information.The timing of interstimulus intervals(ISIs)plays a crit...Background Vibrotactile feedback systems are widely used in assistive technology,wearable devices,and virtual environments to deliver precise tactile information.The timing of interstimulus intervals(ISIs)plays a critical role in determining how accurately users perceive and interpret vibrotactile patterns.The optimal use of ISIs can increase the effectiveness of these systems,improve user interaction,and enable reliable,intuitive feedback in diverse applications.We examined how different interstimulus intervals ISIs impact the accuracy of vibrotactile pattern recognition.Methods Participants wore a forearm-mounted device with six voice coil actuators arranged in a 3×2 grid,delivering Braille-based vibrotactile patterns sequentially at ISIs ranging from 10 to 2500 ms.Eight participants performed identification tasks involving Icelandic Braille patterns categorized as either short(2-3 actuators)or long(4-5 actuators).A repeated measures ANOVA was conducted to assess the effects of ISI,pattern type,and practice(across two testing blocks)on pattern recognition accuracy.Results For short patterns,accuracy was highest(92%-98%)at ISIs of 50-700 ms,with peak performance at 300 ms.For long patterns,accuracy reached 86%-94%at ISIs of 100-500 ms,peaking at 400 ms.Participants were more accurate with short patterns,and performance improved significantly over time for both short and long patterns,highlighting the importance of training for vibrotactile pattern recognition.Conclusions These results underscore the importance of careful selection of ISIs in vibrotactile feedback systems for accurate pattern identification.The findings provide valuable insights for conveying tactile information using wearable devices,contributing to better tactile feedback and performance in applications requiring precise vibrotactile information delivery.展开更多
Purpose-The indoor vibration compaction test(IVCT)was a key step in controlling the compaction quality for high-speed railway graded aggregate(HRGA),which currently had a research gap on the assessment indicators and ...Purpose-The indoor vibration compaction test(IVCT)was a key step in controlling the compaction quality for high-speed railway graded aggregate(HRGA),which currently had a research gap on the assessment indicators and compaction parameters.Design/methodology/approach-To address these issues,a novel multi-indicator IVCT method was proposed,including physical indicator dry density(ρd)and mechanical indicators dynamic stiffness(Krb)and bearing capacity coefficient(K20).Then,a series of IVCTs on HRGA under different compaction parameters were conducted with an improved vibration compactor,which could monitor the physical-mechanical indicators in real-time.Finally,the optimal vibration compaction parameters,including the moisture content(ω),the diameter-to-maximum particle size ratio(Rd),the thickness-to-maximum particle size ratio(Rh),the vibration frequency(f),the vibration mass(Mc)and the eccentric distance(re),were determined based on the evolution characteristics for the physical-mechanical indicators during compaction.Findings-All results indicated that theρd gradually increased and then stabilized,and the Krb initially increased and then decreased.Moreover,the inflection time of the Krb was present as the optimal compaction time(Tlp)during compaction.Additionally,optimal compaction was achieved whenωwas the water-holding content after mud pumping,Rd was 3.4,Rh was 3.5,f was the resonance frequency,and the ratio between the excitation force and the Mc was 1.8.Originality/value-The findings of this paper were significant for the quality control of HRGA compaction.展开更多
This paper presents a novel design method of force rebalance control for the sense mode of micromachined vibratory gyroscopes.Specific theoretical deductions are performed to identify a precise linear model of the ope...This paper presents a novel design method of force rebalance control for the sense mode of micromachined vibratory gyroscopes.Specific theoretical deductions are performed to identify a precise linear model of the open loop system of the sense mode,which is crucial for the PI controller design.The frequency responses obtained by experimental tests agree well with those calculated with the theoretical model,indicating the accuracy of the theoretical analyses.Experimental results demonstrate that the bandwidth of the closed loop is extended to 94.8 Hz from 2.3 Hz in the open loop and the quadrature signal is suppressed by about 64 dBV in the closed loop system.The overshoot and stable time in the step response of the closed loop system are measured to be about 15% and 35 ms,respectively.The mode-splitting gyroscope with the closed loop controlled sense mode achieves a scale factor of 41.0 mV/deg/s with nonlinearity of 0.09% and asymmetry of 1%,and a bias instability of 4.0 °/h with angle random walk of 0.171 deg/h1/2.展开更多
Subsoiling is essential in the tillage of banana planting,as banana plants have a fairly sturdy pseudostem and wide row spacing while soil tends to be compacted.In this study,a bionic vibrating subsoiler for banana fi...Subsoiling is essential in the tillage of banana planting,as banana plants have a fairly sturdy pseudostem and wide row spacing while soil tends to be compacted.In this study,a bionic vibrating subsoiler for banana fields was developed,verified,and evaluated.The vibrator was designed based on crank-rocker mechanism while the bionics design was used for subsoiler development.The forces on the susboiler were analyzed to verify the strength of the subsoiler tine.To test the performance of the subsoiler,field tests were conducted to measure the draft force and fuel consumption.There was approximately 14%reduction in the draft force and 22%increase in the fuel consumption in vibrating mode compared with that in non-vibrating mode.In conclusion,the study results could be applied in China’s tropical agricultural regions.展开更多
Normal sexual and reproductive functions depend largely on neurological mechanisms. Neurological defects in men can cause infertility through erectile dysfunction, ejaculatory dysfunction and semen abnormalities. Amon...Normal sexual and reproductive functions depend largely on neurological mechanisms. Neurological defects in men can cause infertility through erectile dysfunction, ejaculatory dysfunction and semen abnormalities. Among the major conditions contributing to these symptoms are pelvic and retroperitoneal surgery, diabetes, congenital spinal abnormalities, multiple sclerosis and spinal cord injury, Erectile dysfunction can be managed by an increasingly invasive range of treatments including medications, injection therapy and the surgical insertion of a penile implant. Retrograde ejaculation is managed by medications to reverse the condition in mild cases and in bladder harvest of semen after ejaculation in more severe cases. Anejaculation might also be managed by medication in mild cases while assisted ejaculatory techniques including penile vibratory stimulation and eiectroejaculation are used in more severe cases. If these measures fail, surgical sperm retrieval can be attempted. Ejaculation with penile vibratory stimulation can be done by some spinal cord injured men and their partners at home, followed by in-home insemination if circumstances and sperm quality are adequate. The other options always require assisted reproductive techniques including intrauterine insemination or in vitrofertilization with or without intracytoplasmic sperm injection. The method of choice depends largely on the number of motile sperm in the ejaculate.展开更多
Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero...Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero-phase synchronization of the machine is non-stationary and it-phase synchronization is stable. Under half-forcible synchronization condition in which only one motor is controlled being synchronous to another, only lag synchronization near zero-phase synchronization can be realized. Both of the characteristics have never been revealed with classical theory quantitatively. The problem is solved by means of establishing an electromechanical coupling mathematical model of the system and numerical analysis of the starting processes.展开更多
基金This work was supported by the Active Control Rotor Technology Project(No.FKFB20231108055)the National Natural Science Foundation of China(No.11972181)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX21_0228).
文摘Piecewise linear blade twist is studied as a method for reducing the rotor vibratory loads.A rotor model based on an elastic beam concept is used to predict the loads.A four-bladed rotor with a shape similar to the UH-60 rotor is used as a baseline for comparisons.The blade is divided into three segments,which are inner,middle and outer segments respectively.Effect of the twist at different segments on the loads is discussed.The twists at all the segments can reduce the 4/rev(revolution)vertical hub force at low speeds.The 4/rev force can be reduced by 99.5%with a-24°/R(R is the blade radius)twist at the middle segment at 80 km/h.The twist at the inner segment is not helpful for reducing the 4/rev rolling and pitching moments,while the twists at other segments can control both the moments at most speeds.A parameter sweep is conducted to minimize these loads.To reduce the 4/rev force,all the segments need to be twisted at low speeds,while untwisted blades perform better at high speeds.For controlling the 4/rev moments,the outer segment should be highly twisted at low speeds,while high twists at the middle segment are essential at medium to high speeds.
基金This project is supported by National Natural Science Foundation of China(No.50205008).
文摘Vibratory synchronization transmission (VST) is a kind of special physicalphenomenon in inertia vibration mechanical systems. For an inertia vibration mechanical systemdriven by one pair of motors runs in step, even the power supply of one motor is cut off, the motorcan continue to keep rotating state under the vibration exciting of the machine body driven by onlyone other motor. And its rotating frequency will be the same as that of the other one. The transientprocess of this wonderful physical phenomenon has not been described quantitatively according tocurrent-existing mechanical models. On the basis of investigation of the engineering characteristicsof VST, a mechanical and electrical coupling mathematical model of a two-shaft inertia vibrationmachine is established. With this model, the transient process of VST is recurred quantitatively andsuccessfully, and a reasonable explanation is given.
基金Supported by National Natural Science Foundation of China(Grant Nos.51335011,51505489)
文摘Mechanical Quality factor（Q factor） of the resonator is an important parameter for the cylinder vibratory gyroscope（CVG）. Traditional analytical methods mainly focus on a partial energy loss during the vibration process of the CVG resonator, thus are not accurate for the mechanical Q factor prediction. Therefore an integrated model including air damping loss, surface defect loss, support loss, thermoelastic damping loss and internal friction loss is proposed to obtain the mechanical Q factor of the CVG resonator. Based on structural dynamics and energy dissipation analysis, the contribution of each energy loss to the total mechanical Q factor is quantificationally analyzed. For the resonator with radius ranging from 10 mm to 20 mm, its mechanical Q factor is mainly related to the support loss, thermoelastic damping loss and internal friction loss, which are fundamentally determined by the geometric sizes and material properties of the resonator. In addition, resonators made of alloy 3J53 （Ni42CrTiA1）, with different sizes, were experimentally fabricated to test the mechanical Q factor. The theoretical model is well verified by the experimental data, thus provides an effective theoretical method to design and predict the mechanical Q factor of the CVG resonator.
基金This work was supported by the Natural Science Foundation of Jiangsu Province(BK20170681,BK20180701)the National Natural Science Foundation of China(51675281).
文摘The vibratory roller is a piece of vital construction machinery in the field of road construction.The unmanned vibratory roller efficiently utilizes the automated driving technology in the vehicle engineering field,which is innovative for the unmanned road construction.This paper develops and implements the autonomous construction system for the unmanned vibratory roller.Not only does the roller have the function of remote-controlled driving,but it also has the capability of autonomous road construction.The overall system design uses the Programmable Logic Controller(PLC)as the kernel controller.It establishes the communication network through multiple Input/Output(I/O)modules,Recommended Standard 232(RS232)serial port,Controller Area Network(CAN)bus,and wireless networks to control the roller vehicle completely.The locating information is obtained through the Global Navigation Satellite System(GNSS)satellite navigation equipment group to support the process of autonomous construction.According to the experimental results,the autonomous construction system can finally enable the roller to perform driving operations and construction independently,which was a significant step forward in engineering application.
基金The National Key Research and Development Plan(No.2019YFB2006402)
文摘In order to evaluate the performance of semi-active cab’s hydraulic mounts(SHM)of the off-road vibratory roller with the optimal fuzzy-PID(proportional integral derivative)control,a nonlinear dynamic model of the vehicle interacting with off-road terrains is established based on Matlab/Simulink software.The weighted root-mean-square(RMS)acceleration responses of the driver’s seat heave and the cab’s pitch angle are chosen as objective functions.The SHM is then optimized and analyzed via the optimal fuzzy-PID control under different operation conditions.The simulations results show that the driver’s ride comfort and the cab shaking are greatly affected by the off-road terrains under various operating conditions of the vehicle,especially at the speed from 8 to 12 km/h on a very poor terrain surface of Grenville soil ground under the vehicle travelling.With SHM using the optimal fuzzy-PID control,the driver’s ride comfort and the cab shaking are clearly improved under various operation conditions of the vehicle,particularly at the speed from 6 to 7 km/h of the vehicle traveling.
基金This project is supported by National Natural Science Foundation of China(No.50305036).
文摘The effect of vibratory stress relief （VSR） is usually evaluated with the indirect method of observing the change of amplitude frequency response characteristics of structures. A new kind of evaluating method of VSR based on the ultrasonic time-of-arrival method （UTM）, which can obtain the residual stress directly through measuring the propagation time of ultrasonic wave in the material, is presented. At first, the principle of the measuring method of residual stress based on UTM is analyzed. Then the measuring system of the method is described, which is in virtue of ultrasonic flaw detector and high-sampling-rate digital oscillograph. And a set of calibration system that contains a piece of standard specimen is also introduced. Experimental results prove the relation between the residual stress and the propagation time of ultrasonic in workpieces. Finally, the measuring and calibration systems are applied in evaluating the effect of VSR. The final test results show that the method is effective.
基金supported by the National Natural Science Foundation of China(52001267)Tianjin Port Engineering Institute Co.,Ltd.,and Eunsung O&C Offshore Marine and Construction(EUNSUNG19EG01).
文摘The Hong Kong–Zhuhai–Macao Bridge(HZMB)involved the installation of 120 mega-cylinders with a diameter of 22 m,weights up to 513 t,and penetration depths up to 33 m using an eight-vibratory hammer group.Due to the lack of engineering experience on the drivability of large-diameter cylinders under multiple vibratory hammers,predicting the penetration rate and time of steel cylinders is an open challenge that has a considerable impact on the construction control of the HZMB.In this study,the vibratory penetration of large-diameter steel cylinders in the HZMB is investigated based on geological surveys,field monitoring,and drivability analysis.The vibratory penetration rate,installation accuracy,and dynamic responses of the steel cylinders at both the eastern and western artificial islands are analyzed.The dynamic soil resistance has a great influence on the cylinder drivability.However,the current design methods for estimating the vibratory driving soil resistance are proven inaccurate without considering the scale effects.Therefore,a modified method with a normalized effective area ratio A_(r,eff)is proposed in this study to calculate the vibratory soil resistance for open-ended thin-wall cylinders under unplugged conditions.Considering the scale effects on the vibratory driving soil resistance,the proposed method leads to closer results to the measured data,providing a reference for future engineering practice.
基金supported in part by the National Natural Science Foundation of China (11672007, 11672189, and 11290152)the Beijing Natural Science Foundation (3172003)
文摘The linear and nonlinear dynamic responses of a vibratory ring gyroscope are investigated in this study focusing on the response mechanism of such a vibratory gyroscope. It is found that the nonlinear equations governing the drive and sense directions are coupled through both inertial linear and geometric nonlinear terms. Nonlinear responses are studied based on the full coupled nonlinear dynamic equations. The varying amplitude on the sense direction is analyzed for different input angular rates. The effect of nonlinearity on the ring gyroscope system is performed by comparing the results of nonlinear responses to those of linear responses. The contributions of some parameters to the amplitude responses and gyroscope sensitivity are analyzed, the conclusions of which provide guidelines to improve the sensitivity of the vibratory ring gyroscopes.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.1167218911772009 and 12072311)and High-Level Talents Program of Yangzhou University.
文摘Micro-electro-mechanical system(MEMS)gyroscopes are an important sort of inertial sensor for identifying parameters of spinning structures,such as the spinning speed and angular deviation,based on the Coriolis effect.In this paper,the nonlinear mechanism of MEMS vibratory ring gyroscopes is analyzed by applying a fully coupled nonlinear model,in which the gyroscopic coupling and geometrically and structurally nonlinear couplings are all taken into account.The coupled differential equations governing the drive and sense motions are established via the Lagrangian equations.Numerical simulation is conducted,and the key nonlinear components and energy transfer behaviors between the drive and sense modes are elucidated.It is revealed that the cubic rigidity nonlinearity is another significant factor leading to the coupling between the drive and sense modes other than the gyroscopic coupling.Perturbation analysis is also carried out by using the method of multiple scales.The nonlinear frequency-amplitude responses of the drive and sense vibrations are obtained,and comprehensive parametric studies are performed.The significant effects of system damping,excitation amplitude,drive amplitude and spinning speed on the responses are discussed,which will facilitate to improve the nonlinear performance and sensitivity of the gyroscope.
基金the National Natural Science Foundation of China(Nos.51428901 and 51379122)
文摘Factors directly affecting the extraction rate of the piles pulled out by a vibratory pulling system are summarized and classified into five categories(excitation force,resistance,vibration amplitude,pile plumbness keeping,and slowing down at the later stage) from the mechanics and engineering practice.Field tests on steel sheet piles extracted by vibratory technique in different soil conditions are conducted to ascertain how these factors affect the extraction rate of a pile with regard to three major actors of vibratory pile pulling:the pile to be extracted,the selected pulling system,and the imposed soil conditions.The extraction rates of three different sheet pile types(having up to four different lengths) pulled out by two different vibratory pulling systems are documented.The piles with different lengths and types,pulled out with or without a clutch,have different extraction rates.The working parameters governing the vibratory hammer,such as excitation force and vibration amplitude,exert significant influences on the rate of pile extraction,especially in the early stages of up-lift process.The extraction rate of the piles driven in different soil conditions is uniform because different extraction resistances mainly refer to shaft friction.The properties of the pile-soil interface influence the extraction rate of the piles,and the extraction rate decreases with the time for which the piles have been buried in the earth.
基金Project(2003AA430200)supported by the National High-Tech Research and Development Program of China
文摘Based on the working principle of vibratory excavation of hydraulic excavator,the expression of digging resistance changed with time under sine wave inspiritment was deduced;a comparison analysis was given after calculating the forces status of rock and soil under static load and vibratory load respectively by using MATLAB;and then RFPA-2D(rock failure process analysis code)was used to make comparison of simulation experiment on rock and soil failure process under static load and vibratory load.The results demonstrate that,compared with the normal excavation under the same situation,the digging resistance and the energy consumption can be reduced by respectively 30%and 60%at maximum,and that the working efficiency can be increased by 45%at maximum owing to vibratory excavation.
基金The National Key Research and Development Plan(No.2019YFB2006402)Talent Introduction Fund Project of Hubei Polytechnic University(No.19XJK17R)the Joint Key Project Founded by Southeast University and Nanjing Medical University(No.2019DN0011)。
文摘Based on the advantages of hydraulic and pneumatic mounts,a new hydro-pneumatic mount(HPM)is proposed to improve the low-frequency ride comfort of vibration rollers.Through the experiment of the vibratory roller,a nonlinear vehicle dynamic model working on off-road soil grounds is then established to assess the HPM's ride comfort in the low-frequency region.Two indices,the power spectral density(PSD)acceleration and root mean square(RMS)acceleration of the operator vibration and cab shaking,are chosen as objective functions in both the frequency and time regions.The research results show that when the cab isolations are equipped with the HPM,the RMS values of the operator's seat,cab's pitch and roll angles are reduced by 35%,42%and 53%;and the maximum PSD of the operator's seat,cab's pitch and roll angles are decreased by 39%,59%and 65%,respectively.Consequently,the characteristics of the nonlinear damper and high-static stiffness of HPM can greatly reduce the operator vibration and cab shaking in the low-frequency region when compared to the vibratory roller's cab using the rubber mounts.
文摘Vibratory stimulation but also motor imagery and action observation can induce corticomotor modulation, as a bottom-up stimulus and top-down stimuli, respectively. However, it remains unknown whether the combination of motor imagery, action observation, and vibratory stimulation can effectively increase corticomotor excitability. This study aimed to investigate the effect of motor imagery and/or action observation, in the presence or absence of vibratory stimulation, on the corticomotor excitability of healthy young adults. Vibratory stimulation was provided to the palm of the right hand. Action observation consisted in viewing a movie of someone else’s finger flexion and extension movements. The imagery condition required the participants to imagine they were moving their fingers while viewing the movie and attempting to move their fingers in accordance with the movie. Eleven right-handed healthy young adults were asked to perform six conditions randomly: 1) vibratory stimulation, imagery, and action observation, 2) vibratory stimulation and action observation, 3) vibratory stimulation and viewing of a blank screen, 4) imagery and action observation, 5) action observation, and 6) viewing of a blank screen. Single-pulse transcranial magnetic stimulation was conducted to assess corticomotor excitability and the peak-to-peak amplitude of the motor evoked potentials. The results showed that vibratory stimulation increases corticospinal excitability. The findings further revealed that performing motor imagery while viewing finger movement is more effective at inducing an augmentation of corticomotor excitability compared to action observation alone. Thus, the combination of motor imagery, action observation, and vibratory stimulation can effectively augment corticomotor excitability.
基金support provided by Intelligent Transportation System and Soil Dynamic Laboratory at Department of Civil Engineering,Delhi Technological University,Delhi,India.Furthermore,the support received under Project F.No.DTU/IRD/619/2105 of IRD DTU,Delhi,is thankfully acknowledged.
文摘Computer programming-based numerical programs are firmly established in geotechnical engineering,with rapid growth of finite element modeling and machine learning techniques gaining much attention both in practice and academia.This study is intended to expedite the dissemination of advanced computer applications in terms of finite element simulation and machine learning models by investigating the dynamic response of geomaterials subjected to vibratory loads.Several trial models were built to perform the experimental investigations with a vibratory shaker,signal generator,several accelerometers,a data collection system,and other ancillary devices.The implicit integration techniques in commercialized software were adopted for numerical simulations.After data collection from numerical simulation,models were chosen,trained,and assessed to produce predictions that were then used in this study.Several technologies,including the ensemble boosted tree,squared exponential Gaussian Process Regression(GPR),Matern 5/2 GPR,exponential GPR,and decision tree architectures(fine and medium),were used to forecast the displacement of confined geomaterial.The displacement-depth ratio was found rising to 80%in the frequency range of 5 to 25 Hz,suggesting a considerable change in the behavior of the geomaterial.The Matern 5/2 GPR model showed better accuracy with an R2 value of 0.99,indicating an outstanding predictive ability.The Matern 5/2 GPR and boosted tree models could help better understand the links between displacement and its distribution along the direction of load application.The outcomes of this study based on computer-aided finite element programs can be effectively implemented in machine learning to develop computer programs.In conclusion,the computational machine learning models adopted in this study offer a new insight for uncovering hidden intrinsic laws and creating new knowledge for geotechnical researchers and practitioners.
基金Supported by the Icelandic Technological Development Fund(Project No.1910271).
文摘Background Vibrotactile feedback systems are widely used in assistive technology,wearable devices,and virtual environments to deliver precise tactile information.The timing of interstimulus intervals(ISIs)plays a critical role in determining how accurately users perceive and interpret vibrotactile patterns.The optimal use of ISIs can increase the effectiveness of these systems,improve user interaction,and enable reliable,intuitive feedback in diverse applications.We examined how different interstimulus intervals ISIs impact the accuracy of vibrotactile pattern recognition.Methods Participants wore a forearm-mounted device with six voice coil actuators arranged in a 3×2 grid,delivering Braille-based vibrotactile patterns sequentially at ISIs ranging from 10 to 2500 ms.Eight participants performed identification tasks involving Icelandic Braille patterns categorized as either short(2-3 actuators)or long(4-5 actuators).A repeated measures ANOVA was conducted to assess the effects of ISI,pattern type,and practice(across two testing blocks)on pattern recognition accuracy.Results For short patterns,accuracy was highest(92%-98%)at ISIs of 50-700 ms,with peak performance at 300 ms.For long patterns,accuracy reached 86%-94%at ISIs of 100-500 ms,peaking at 400 ms.Participants were more accurate with short patterns,and performance improved significantly over time for both short and long patterns,highlighting the importance of training for vibrotactile pattern recognition.Conclusions These results underscore the importance of careful selection of ISIs in vibrotactile feedback systems for accurate pattern identification.The findings provide valuable insights for conveying tactile information using wearable devices,contributing to better tactile feedback and performance in applications requiring precise vibrotactile information delivery.
基金funded by the National Key R&D Program“Transportation Infrastructure”project(No.2022YFB2603400)the Technology Research and Development Plan Program of China State Railway Group Co.,Ltd.(No.Q2024T001)the National project pre research project of Suzhou City University(No.2023SGY019).
文摘Purpose-The indoor vibration compaction test(IVCT)was a key step in controlling the compaction quality for high-speed railway graded aggregate(HRGA),which currently had a research gap on the assessment indicators and compaction parameters.Design/methodology/approach-To address these issues,a novel multi-indicator IVCT method was proposed,including physical indicator dry density(ρd)and mechanical indicators dynamic stiffness(Krb)and bearing capacity coefficient(K20).Then,a series of IVCTs on HRGA under different compaction parameters were conducted with an improved vibration compactor,which could monitor the physical-mechanical indicators in real-time.Finally,the optimal vibration compaction parameters,including the moisture content(ω),the diameter-to-maximum particle size ratio(Rd),the thickness-to-maximum particle size ratio(Rh),the vibration frequency(f),the vibration mass(Mc)and the eccentric distance(re),were determined based on the evolution characteristics for the physical-mechanical indicators during compaction.Findings-All results indicated that theρd gradually increased and then stabilized,and the Krb initially increased and then decreased.Moreover,the inflection time of the Krb was present as the optimal compaction time(Tlp)during compaction.Additionally,optimal compaction was achieved whenωwas the water-holding content after mud pumping,Rd was 3.4,Rh was 3.5,f was the resonance frequency,and the ratio between the excitation force and the Mc was 1.8.Originality/value-The findings of this paper were significant for the quality control of HRGA compaction.
文摘This paper presents a novel design method of force rebalance control for the sense mode of micromachined vibratory gyroscopes.Specific theoretical deductions are performed to identify a precise linear model of the open loop system of the sense mode,which is crucial for the PI controller design.The frequency responses obtained by experimental tests agree well with those calculated with the theoretical model,indicating the accuracy of the theoretical analyses.Experimental results demonstrate that the bandwidth of the closed loop is extended to 94.8 Hz from 2.3 Hz in the open loop and the quadrature signal is suppressed by about 64 dBV in the closed loop system.The overshoot and stable time in the step response of the closed loop system are measured to be about 15% and 35 ms,respectively.The mode-splitting gyroscope with the closed loop controlled sense mode achieves a scale factor of 41.0 mV/deg/s with nonlinearity of 0.09% and asymmetry of 1%,and a bias instability of 4.0 °/h with angle random walk of 0.171 deg/h1/2.
基金the Special Fund for Agro-scientific Research in the Public Interest from the Ministry of Agriculture,China(Grant No.201503136)the National Natural Science Foundation of China(Grant No.51565010)the National Natural Science Foundation of Hainan Province(Grant No.20163038)。
文摘Subsoiling is essential in the tillage of banana planting,as banana plants have a fairly sturdy pseudostem and wide row spacing while soil tends to be compacted.In this study,a bionic vibrating subsoiler for banana fields was developed,verified,and evaluated.The vibrator was designed based on crank-rocker mechanism while the bionics design was used for subsoiler development.The forces on the susboiler were analyzed to verify the strength of the subsoiler tine.To test the performance of the subsoiler,field tests were conducted to measure the draft force and fuel consumption.There was approximately 14%reduction in the draft force and 22%increase in the fuel consumption in vibrating mode compared with that in non-vibrating mode.In conclusion,the study results could be applied in China’s tropical agricultural regions.
文摘Normal sexual and reproductive functions depend largely on neurological mechanisms. Neurological defects in men can cause infertility through erectile dysfunction, ejaculatory dysfunction and semen abnormalities. Among the major conditions contributing to these symptoms are pelvic and retroperitoneal surgery, diabetes, congenital spinal abnormalities, multiple sclerosis and spinal cord injury, Erectile dysfunction can be managed by an increasingly invasive range of treatments including medications, injection therapy and the surgical insertion of a penile implant. Retrograde ejaculation is managed by medications to reverse the condition in mild cases and in bladder harvest of semen after ejaculation in more severe cases. Anejaculation might also be managed by medication in mild cases while assisted ejaculatory techniques including penile vibratory stimulation and eiectroejaculation are used in more severe cases. If these measures fail, surgical sperm retrieval can be attempted. Ejaculation with penile vibratory stimulation can be done by some spinal cord injured men and their partners at home, followed by in-home insemination if circumstances and sperm quality are adequate. The other options always require assisted reproductive techniques including intrauterine insemination or in vitrofertilization with or without intracytoplasmic sperm injection. The method of choice depends largely on the number of motile sperm in the ejaculate.
基金This project is supported by National Natural Science Foundation of China (No.59875010)
文摘Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero-phase synchronization of the machine is non-stationary and it-phase synchronization is stable. Under half-forcible synchronization condition in which only one motor is controlled being synchronous to another, only lag synchronization near zero-phase synchronization can be realized. Both of the characteristics have never been revealed with classical theory quantitatively. The problem is solved by means of establishing an electromechanical coupling mathematical model of the system and numerical analysis of the starting processes.
