Levitation Mass Research Articles

Low energy dissipation superconducting flywheel based on structural design

Superconducting flywheels have potential application value in aerospace field, and its suspension time is a key factor. Alternating Current (AC) loss associated with rotation is an important parameter that affects the suspension time, so it is very important to study how to reduce the AC loss. Recently, a method of preparing YBa2Cu3O7−x (YBCO) high-temperature superconducting flywheels by Direct-Ink-Writing (DIW) 3D printing was developed. In this paper, the circular hole superconducting flywheel prepared by this method is optimized by the idea of structural optimization. Based on the finite element method, the AC loss before and after optimization is calculated and analyzed. It is found that the elliptical holes make the superconducting flywheel have lower AC loss than circular holes, with a reduction of 58.49%. Then, the YBCO superconducting flywheel with an optimized elliptical structure was prepared by the DIW 3D printing method. The magnetic levitation experiment found that the levitation time of the optimized superconducting flywheel was increased to 162 s compared with the previous 120 s under the same conditions, and the optimized structure had a higher levitation mass ratio. It provides theoretical and experimental support for reducing the AC loss of superconductors by applying the idea of structural optimization design in engineering practice.

Development of a New Data Processing System for Increasing the Accuracy of a Levitation Mass Method (LMM) based Measurement

Levitation Mass Method (LMM) is the method as a material tester to evaluate the mechanical response of general objects against impact forces. In this method, a mass is made to collide with material to be tested and the impulse, i.e. the time integration of the impact force, is measured highly accurately as a change in momentum of the mass. To realize linear motion with sufficiently small friction acting on the mass, a pneumatic linear bearing is used. The inertial force acting on the mass is calculated from the velocity of the mass. The velocity is determined, highly accurately by means of measuring the Doppler shift frequency of a laser light beam reflected on the mass using an optical interferometer. To determine the Doppler frequency shift for LMM data processing, the method for estimating the frequency is necessary. Several methods have been developed to estimate the frequency for the LMM data processing with high accuracy, i.e. Zero-Crossing Average Method (ZAM), Zero-Crossing Fitting Method (ZFM), Sine Wave Fitting, and Zero-crossing Sine Wave Fitting. All methods realized using the zero-crossing point of the waveform obtained from the digitizer. A better method to estimate frequency on the digitized waveform will enable higher precision for a more accurate result. In this research, a new method that can improve the accuracy has been developed. The program was developed using data segmentation to obtain the frequency of the digitized waveforms. The developed program has the smallest error ( 1,98 X 10^-10 for N= 200) compare to other methods (2,31 X 10-3 for ZAM; 1,10X10-3 for ZFM; and 8,69 X10-4 for Zero-crossing Sine Wave Fitting).

Quantitative Analysis of Pharmaceutical Drugs Using a Combination of Acoustic Levitation and High Resolution Mass Spectrometry.

A combination of acoustic levitation, laser vaporization, and atmospheric pressure chemical ionization mass spectrometry (APCI-MS) is presented in this study that enabled sensitive analysis of pharmaceutical drugs from an aqueous sample matrix. An unfocused pulsed infrared laser provided contactless sample desorption from the droplets trapped inside an acoustic levitator by activation of the OH stretching band of aqueous and alcoholic solvents. Subsequent atmospheric pressure chemical ionization was used between the levitated droplet and the mass spectrometer for postionization. In this setup, the unfocused laser gently desorbed the analytes by applying very mild repulsive forces. Detailed plume formation studies by temporally resolved schlieren experiments were used to characterize the liquid gas transition in this process. In addition, the role of different additives and solvent composition was examined during the ionization process. The analytical application of the technique and the proof-of-concept for quantitative analysis were demonstrated by the determination of selected pharmaceutical drugs in aqueous matrix with limits of quantification at the lower nanomolar level and a linear dynamic range of 3-4 orders of magnitude.

Analysis of Quasi-Zero Power Characteristic for a Permanent Magnetic Levitation System with a Variable Flux Path Control Mechanism

This article focuses on the analysis of the quasi-zero power characteristic for a permanent magnetic levitation system with a variable flux path control mechanism. The system mainly consists of a disk permanent magnet, a pair of yokes, and a rotary actuator. The permanent magnet magnetized diametrically is rotated by the actuator, which can achieve the control of the levitation force by changing the flux. Unlike the electromagnetic system, the input to the actuator is used to maintain the rotation angle corresponding to the equilibrium position, not to directly produce a magnetic force. Therefore, the proposed system possesses a lower power consumption. Analysis of mechanism, current model, and different levitation control strategies are presented in this article. With the variable air gap length control and the constant air gap length control, the permanent magnetic levitation system performs well in levitation with quasi-zero power in loading experiments. The constant air gap control is demonstrated to possess higher safety when the levitation mass is changed, which has the potential for magnetic levitation transportation.

Effect of Mass Added to a Force Transducer on the Dynamic-Force Correction Method

Dynamic-error caused by the mass attached to the sensing part of a force transducer is experimentally investigated using the Levitation Mass Method (LMM), in which the dynamic-force applied to the force transducer is measured based on the definition of force, i.e. the product of mass and acceleration. It is experimentally proved that the change in the dynamic correction coefficient (DCC) is proportional to the additional mass as expected by the theory. The effective mass and the effective spring constant of the transducer with the additional mass are estimated from the experimental result. It is experimentally proved that the DCC for the transducer with the additional mass can be calculated using the estimated properties, i.e. the effective mass and the effective spring constant, and the dynamic-error can be corrected with the calculated DCC.

New technique for dynamic calibration of a force transducer using a drop ball tester

A method to calibrate a force transducer under dynamic conditions has been developed. Calibration is achieved by a drop ball test based on the levitation mass method using an optical interferometer. From the conducted experiments, the output of the force transducer could be corrected, in line with the previous paper written by the authors. Moreover, the dynamic correction coefficient could be obtained by this method, even without an expensive air slider, which was used in our previous method. The calibration performed by the developed method proved to be very significant in correcting the dynamic force measurement error by the force transducer with a very small root mean square (RMS) error compared to the results of measurement in the absence of calibration and dynamic correction. The RMS error of measurement result by the force transducer with dynamic calibration and dynamic correction using the developed method is about 1.6 N. This error is equivalent to 1% of the maximum force applied to the force transducer, which is approximately 160 N.

Corrigendum

Wang Y, Shu D, Fujii Y, et al. Comparison between numerical analysis and the levitation mass method measurement test of a spherical structure early impacting water. Advances in Mechanical Engineering 2018; 10(1): 1–15. DOI: 10.1177/1687814017748076 In the above-referenced article, the names of the third, fourth, fifth, and sixth authors were displayed incorrectly. The full author list should appear as follows: Yonghu Wang, Dongwei Shu, Yusaku Fujii, Akihiro Takita, Tsuneaki Ishima and Ryosuke Araki.

Comparison between numerical analysis and the levitation mass method measurement test of a spherical structure early impacting water

In order to precisely measure water impact loads of a spherical structure vertically dropping onto a calm water surface, a new validity check of the analysis using the levitation mass method experiment is proposed. The main feature of levitation mass method experiment is to obtain a better estimation of early water impact loads through the application of Doppler effect. Experimental results of different heights are verified based on the Assessment Index and are in comparison with the classical experimental data for validation purpose. It shows that the levitation mass method measurement is useful and effective to obtain the water impact loads for the crashworthiness analysis. Besides, early water impact hydrodynamic behaviors are simulated based on the nonlinear explicit finite element method, together with application of a multi-material arbitrary Lagrangian–Eulerian solver. A penalty coupling algorithm is utilized to realize fluid–structure interaction between the spherical body and fluids. Convergence studies are performed to construct the proper finite element model by the comparison with experimental results, where mesh sensitivity, contact stiffness, and time-step size parametric studies are thoroughly investigated. The comparisons between experimental and numerical results show good consistency by the prediction of the water impact coefficients on the structure.

Precision Mechanical Measurement Using the Levitation Mass Method (LMM)

The present status and the future prospects of a method for precision mass and force measurement, the levitation mass method (LMM), are reviewed. The LMM has been proposed and improved by the authors. In the LMM, the inertial force of a mass levitated using a pneumatic linear bearing is used as the reference force applied to the objects under test, such as force transducers, materials or structures. The inertial force of the levitated mass is measured using an optical interferometer. The three typical applications of the LMM, i.e. the dynamic force calibration, the micro force material tester and the space scale, are reviewed in this paper.

Real Time Monitoring of Containerless Microreactions in Acoustically Levitated Droplets via Ambient Ionization Mass Spectrometry.

Direct in-droplet (in stillo) microreaction monitoring using acoustically levitated micro droplets has been achieved by combining acoustic (ultrasonic) levitation for the first time with real time ambient tandem mass spectrometry (MS/MS). The acoustic levitation and inherent mixing of microliter volumes of reactants (3 μL droplets), yielding total reaction volumes of 6 μL, supported monitoring the acid-catalyzed degradation reaction of erythromycin A. This reaction was chosen to demonstrate the proof-of-principle of directly monitoring in stillo microreactions via hyphenated acoustic levitation and ambient ionization mass spectrometry. The microreactions took place completely in stillo over 30, 60, and 120 s within the containerless stable central pressure node of an acoustic levitator, thus readily promoting reaction miniaturization. For the evaluation of the miniaturized in stillo reactions, the degradation reactions were also carried out in vials (in vitro) with a total reaction volume of 400 μL. The reacted in vitro mixtures (6 μL total) were similarly introduced into the acoustic levitator prior to ambient ionization MS/MS analysis. The in stillo miniaturized reactions provided immediate real-time snap-shots of the degradation process for more accurate reaction monitoring and used a fraction of the reactants, while the larger scale in vitro reactions only yielded general reaction information.

Impact Response Measurement of Bamboo Shinai and CFRP Shinai

Bamboo shinai is a practice sword for kendo which is the Japanese traditional fencing. The effectiveness of the shock absorption of the bamboo shinai has been shown in our previous study. Although shinai is usually made of bamboo, it is also made of carbon fiber reinforced plastic (CFRP). The impact response of bamboo shinai and CFRP shinai is compared. As a result, the difference of peak value of impact force between bamboo shinai and CFRP shinai against similar initial velocity is small. Impact response measurement of each shinai has been carried out using the Levitation Mass Method (LMM) which has been proposed by us. In this method, a mass, which is levitated with a pneumatic linear bearing and hence affected by negligible friction, is made to collide with a shinai under test. Because bamboo is natual product, resource of suitable bamboos for shinai is limited. On the other hand, carbon-fiber-reinforced-plastic (CFRP) can be designed to be suitable for a shinai, which has a fixed shock absorption characteristic for an application to the structure of robot arms. Therefore, if the shock absorption characteristic of CFRP shinai is the same as that of bamboo shinai, CFRP shinai is more suitable for the structure of robot arms.

Design and Fabrication of a Superconducting Relative Gravimeter With a Planar Spring

The relative gravimeter is in high demand to improve the performance of a navigation system. Therefore, we designed, fabricated, and tested a superconducting relative gravimeter. The proposed gravimeter features a superconducting planar spring, an electromagnetic levitation, and a superconducting quantum interference device (SQUID) sensor. The advantages of the superconductor include being able to enable the device with exceptional stability and having an extremely low noise. The coupling spring with electromagnetic levitation can also offer a low resonant frequency for better sensitivity. The device consists of a niobium mass-spring vibrometer having a planar spring, a levitation coil, and a SQUID sensor. The vibrometer was designed by conducting the mathematical analysis and the mechanical–electromagnetic finite element analysis simulation. Both the electrodischarge machining process and the high vacuum-thermal process were applied to fabricate superconducting structures. Experiments to store and discharge a persistent current in the levitation coil were carried out at 4.2 K cryogenic condition to confirm the numerical prediction. An experimental setup with a precision linear actuator was used to verify the relationship between induced inductance and displacement. The test result indicates that the gravimeter can measure the fine movement of the levitation mass by reading a SQUID output and the scale factor is $\sim 28$ mV/ $\mu {\mathrm{ m}}$ .

Impact Response Measurement of a Bamboo Sword “Shinai”

Impact response of a bamboo sword “Shinai” which is a practice sword used in a Japanese traditional fencing and has an unique and simple structure of light-weight bamboo plates for moderating the impact force to the human body, is accurately measured by means of modifying the Levitation Mass Method (LMM). In the method, a mass, which is levitated with an aerostatic linear bearing and hence encounters negligible friction, is made to collide with a bamboo sword under test. During the collision, the Doppler shift frequency of a laser beam reflecting from the mass is accurately measured using an optical interferometer. The velocity, position, acceleration, and inertial force of the mass are calculated from the measured time-varying Doppler shift frequency. The measurement results show that “Shinai” considerably moderates the impact force and its unique structure might be effective for robotics and automobiles to moderate the impact force acting to the human body in the case of accidents.

Impact Response Measurement of Contact Lenses

Impact response of contact lenses is measured using the Levitation Mass Method (LMM). In the LMM, a small mass collides with contact lenses and the impact force is measured with high accuracy as the inertial force of the moving part. A pneumatic linear bearing is used to achieve linear motion with sufficiently small friction acting on the moving part. Hysteresis loop and consumed energy as mechanical characteristics of contact lenses are also calculated.

Frictional Characteristics Measurement of a Ceramic Aerostatic Linear Bearing

The resultant force acting on the moving part of the ceramic aerostatic linear bearing is measured highly accurately as the inertial force of the moving part of the bearing by means of the levitation mass method (LMM). The measurement results of the ceramic aerostatic linear bearing and metal aerostatic linear bearing of different mass are compared. The regression equation of the ceramic aerostatic linear bearing and metal aerostatic linear bearing are calculated. The ceramic linear bearing and metal linear bearing have extremely small frictional force.

Improvement of Software for Dynamic Force Correction of Force Transducers

Software for correcting the dynamic error of the force sensor in the impact force measurement, which uses an output signal of the sensor itself, has been improved. The software corrects the output waveform of the sensor by using the output waveform itself and estimates its uncertainty. In the experiment, the dynamic error of the sensor is evaluated using the Levitation Mass Method (LMM). In the LMM, the impact force applied to the sensor is accurately determined as an inertial force of the moving part of the aerostatic linear bearing. The parameter for correcting the dynamic error is determined from the results of one set of impact measurements of the sensor. Then the validity of the parameter is evaluated by using the results of measurements of the sensor. The uncertainty of the un-corrected force and that of the corrected force are also estimated. In the previous version of the software, the user input “input text-file” which contains force that is calculated based on the static calibration results. On the other hand, the output signal from the sensor is not force. This time, the software has been modified to load input text-file which contains the output signal from the sensor.

New Method for Evaluating Dynamic Characteristics of Cantilever Spring of Vibration Sensor

Copper beryllium (CuBe)is materials that are widely used for mechanical applications. In this paper,the use of copper beryllium for cantilever spring of a vibration sensor will beinformed. Cantilever spring plays important role in a vibration sensor, becauseit transfers vibration energy of the measured system into the sensor.Therefore, it is important to know the dynamic characteristics of thecantilever spring. An optical method, called Levitation Mass Method (LMM), isproposed to measure the dynamic characteristic of the cantilever. In themethod, the force of cantilever spring is measured as the inertial force workedon a mass. A pneumatic linear bearing is used to realize a linear motion withsufficiently small friction acting on the mass, i.e., the moving part of thelinear bearing. The inertial force acting on the mass is calculated from thevelocity of the mass, and the velocity is determined highly accurately by meansof measuring the Doppler shift frequency of the laser light beam reflecting onthe mass using an optical interferometer. It is shown that the proposed methodshows the dynamic characteristic of the vibration sensor well.

Software for correcting the dynamic error of force transducers.

Software which corrects the dynamic error of force transducers in impact force measurements using their own output signal has been developed. The software corrects the output waveform of the transducers using the output waveform itself, estimates its uncertainty and displays the results. In the experiment, the dynamic error of three transducers of the same model are evaluated using the Levitation Mass Method (LMM), in which the impact forces applied to the transducers are accurately determined as the inertial force of the moving part of the aerostatic linear bearing. The parameters for correcting the dynamic error are determined from the results of one set of impact measurements of one transducer. Then, the validity of the obtained parameters is evaluated using the results of the other sets of measurements of all the three transducers. The uncertainties in the uncorrected force and those in the corrected force are also estimated. If manufacturers determine the correction parameters for each model using the proposed method, and provide the software with the parameters corresponding to each model, then users can obtain the waveform corrected against dynamic error and its uncertainty. The present status and the future prospects of the developed software are discussed in this paper.

Determination of Reaction Force in a Toothbrush Tuft using Levitation Mass Method (LMM)

The reaction force of a single toothbrush tuft (group of bristles) against the colliding ogject is measured using the Levitation Mass Method (LMM). In the experiment, a metal object with a rounded tip is made to collide with the surface of the tuft. The metal object, i.e. the moving part of the aerostatic linear bearing, moves horizontally with a suffiently small friction. Since the frictional force acting to the moving part is very small, the inertial force of the moving part is equal to the dynamic reaction force of the tuft. The tested toothbrush tuft used is made of nylon material with 25 bristles, has a length of 10 mm and a diameter of 0.2 mm. The velocity of the moving part is measured precisely from the beat frequency and the rest frequency using an optical interferometer. After getting the velocity, the other mechanical quantities, such as position, acceleration, and inertial force. are calculated numerically. The mechanical friction inside the bearing is determined using the same instrumentation with an average value of 2.05 mN.

The Dynamic Characteristics of Gelled Food Materials against Small Impact Force

The dynamic mechanical characteristics against small impact force of konjak were measured in thisstudy. Konjak is one of the popular and healthy Japanese foods and is the Gunma prefectural specialty. Thereare many studies discussing the sensory characteristics of food materials, however few of them measure thecharacteristics quantitatively and accurately. If it has been done, the detail of sensory properties will be able to bediscussed. We have done the experience and shown the characteristics. Konjak is flexible and slimy food material.We thought konjak is like rubbers and it can be measured the response against small impact force. To measurethe precise dynamic mechanical force, the levitation mass method (LMM) is used. In LMM, a pneumatic linearbearing is used to reduce friction to almost zero, and an optical interferometer is used. The acceleration, velocity,position, and inertial force of the mass are calculated from the measured time-varying frequency due to DopplerEffect, which can be calculated by using the zero-crossing fitting method (ZFM). LMM had been used to onlymeasure the dynamic forces acting on the mass before, but we utilized it to test the mechanical characteristics offood materials. Konjak has the characteristics of viscoelasticity. We have revealed the quantitative and logicalcharacteristics of konjak.