記述言語：英語   掲載種別：研究論文（学術雑誌）  

This study aimed to discover an easy and precise prediction model for the acoustic properties of nanofiber nonwoven fabrics. For this purpose, a prediction model focusing on the two dominant parameters in the Limp frame model-bulk density and flow resistivity-was suggested. The propagation constant and characteristic impedance was generated from the effective density and effective volume modulus generated by the predictive model and treated as a one-dimensional transfer matrix. The sound absorption coefficient was then estimated using the transfer matrix approach. The trend of the normal Incident sound absorption coefficient measured and the sound absorption coefficient obtained from the predictive model were consistent. Thus, it is suggested that the predictive model for the proposed nanofiber nonwoven composite sheet is valid.

DOI： 10.3390/nano12173050

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Zero-mass metamaterials comprise an orifice and a thin film. The resonance between the film and the air mass of the orifice hole is caused by sound waves, which significantly decreases the transmission loss at a specific frequency. The study novelly incorporates acoustic metamaterials in the delay tube of an interference silencer. In this case, it is determined that an interference silencer and a "side-branch silencer with two different branch pipe lengths" can be realized in a single silencer. At certain frequencies, the acoustic mass of the acoustic metamaterial approaches zero, which results in an interference silencer with the full length of the delay tube applied. At other frequencies, the acoustic metamaterial acts as a rigid wall with high transmission loss, thereby reflecting sound waves at the zero-mass metamaterial location. In this case, it is a side-branch silencer with two different tube lengths, corresponding to the tube lengths from the entrance and exit of the delay tube to the zero-mass metamaterial, respectively. The incorporation of zero-mass metamaterial into an interference-type silencer can introduce the silencing effect of a side-branch silencer with two different branch tube lengths without increasing the volume of the interference-type silencer. Theoretical values were obtained using the transfer matrix. Consequently, the theoretical and experimental values were close, enabling us to predict the transmission loss of the proposed silencer.

DOI： 10.3390/ma15155140

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The purpose of this study was to improve the accuracy of the theoretical analysis of sound absorption mechanisms when a back air space is used in nonwoven fabrics. In the case of a nonwoven sheet with a back air space, it can be shown that there is a difference between the experimental results and theoretical analysis results obtained using the Miki model when the area of the nonwoven sheet is large. Therefore, in this study, the accuracy of the theoretical values was improved using the plate vibration model in conjunction with the Miki model. The experimental results showed that when the vibration of the nonwoven sheet was suppressed, the sound absorption coefficient was higher than that of the vibration-prone nonwoven sheet alone. The sound absorption coefficient at the peak frequency was increased by >0.2, especially for 3501BD. Using the support frame, the sound absorption coefficient at the peak frequencies of 3A01A and 3701B was increased to 0.99. In the theoretical analysis of a large-area, vibration-prone nonwoven fabric, in which the vibration of the nonwoven fabric was taken into account, the theoretical values were in agreement with the experimental values, and the accuracy of the theoretical values was improved. Comparing the theoretical values for nonwoven fabrics without high ventilation resistance, the sound absorption coefficient was greater when vibration was not considered. Therefore, it was suggested that the vibration of the nonwoven fabric hinders sound absorption.

DOI： 10.3390/ma15113840

PubMed

researchmap

掲載種別：研究論文（学術雑誌）  

In general, the acoustic effective length of the open end of an air column is longer than its geometric length. Here, the effective increment of the geometric length of an air column is called the open-end correction length, which is an acoustically crucial issue. The purpose of this study is to experimentally clarify the open-end correction length for a slit shape with a narrow clearance. For this reason, the sound absorption coefficient was measured using a sample in which the neck of the Helmholtz resonator was shaped as a slit with a narrow clearance. Next, the open-end correction length (i.e., mass end correction length and resistive end correction length) was calculated backward by comparing the experimental and theoretical sound absorption curves. The resistive end correction increased as the slit width became narrower within the range of 0.5 mm or less for both the center slit and the slit near the wall, indicating a significant discrepancy between the theoretical equation and the estimated value. For the mass end correction, in the case the center slit, the estimated value is close to the theoretical value of in the slit width range from 0.3 mm to 1.0 mm. The results of this study may be useful in eliminating discrepancies in correction values for open-end correction in slits with narrow clearance.

DOI： 10.3397/1/377011

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

We performed a theoretical analysis on collection of equilateral triangular holes with consideration for sound wave attenuation within the tube and then calculated the sound-absorption coefficient and transmission loss. We then compared these results with experimental values. In the experiment, we measured the sound-absorption coefficient and transmission loss of a test sample using impedance measurement tubes with two and four microphones. We estimated the sound-absorption coefficient and transmission loss because of the dimensions of a collection of equilateral triangular holes through theoretical analysis and then compared these results with experimental values. In the present analysis, the propagation constant and characteristic impedance were introduced into a one-dimensional transfer matrix. Considering the effects of sound wave attenuation in the tubule from three-dimensional analysis, we derived the propagation constant and characteristic impedance. Values for the sound-absorption coefficient and transmission loss obtained through the analysis of holes as triangles rather than as circles gave calculation results closer to the experimental values. This is because this method more suitably simulates the effects of the boundary layer that occupies the space within the hole. The results show that the sound absorption coefficient and transmission loss of triangular honeycombs can be estimated with sufficient accuracy using only geometric dimensions and physical properties.

DOI： 10.3397/1/377013

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

In this study, the sound-absorption coefficients of a pin-holder structure consisting of a group of cylinders were estimated and compared with the experimental values for the case where sound waves are incident in the direction perpendicular to the cylinder's axis. To estimate the sound-absorption coefficient, the gap in the pin-holder structure is divided into elements and approximated as being between two parallel planes, taking the exact shape of the divided elements into account. The characteristic impedance and propagation constant of the approximated clearances were calculated and treated as a one-dimensional transfer matrix. The transfer matrices for each element were used to calculate the sound-absorption coefficient. The calculated theoretical values were compared with the experimental ones. In the experiment, the samples were fabricated using a 3D printer, and the sound-absorption coefficient was measured using a two-microphone impedance-measurement tube. Although the experimental and theoretical values differed, they showed similar trends. We also found that the prediction error in the practical sound-absorption coefficient could be reduced by adjusting the diameter of the pins used in the calculation.

DOI： 10.3397/1/377012

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

A structure that possesses a continuous pore space packed with a granular material exhibits acoustic characteristics based on the principle similar to that of a porous material. Such a structure is used in low-noise pavement and ballast track. Therefore, predicting the sound absorption characteristics of a clearance generated in a granular material from the particle diameter and the physical property of gas is useful for engineering. This article deals with two packing models, namely, the simple cubic lattice model and the hexagonal lattice model, to measure the sound absorption coefficient of the structure packed with a granular material whose particle diameter is a few mm. Furthermore, a simple and accurate theoretical analysis that uses a one-dimensional transfer matrix method, which does not require numerous parameters, was performed. Comparing experimental values, when the particle diameter of the granular material was 4 mm, the percentage of the boundary layer in the clearance was moderately larger than when the diameter was 8 mm; therefore, the effect of viscosity on it was larger, and its sound absorption coefficient peak was higher. Moreover, compared with the simple cubic lattice, the hexagonal lattice had a higher percentage of boundary layer in the clearance because of its smaller volume of pore space. Then, the influence of friction due to the viscosity on it was higher, and its sound absorption coefficient peak was higher. In addition, the theoretical values obtained by the proposed analysis method typically matched the experiment values.

DOI： 10.3397/1/376937

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

In this study, a theoretical analysis of the acoustic characteristics of a pin holder structure was conducted. In addition, the sound absorption coefficient, entering its clearance through the geometrical dimension of the clearance or the physical property of air, was calculated. The analysis model approximates the aperture of a pin holder structure as the clearance between two parallel surfaces. Thus, the propagation constant and characteristic impedance were obtained and treated as a one-dimensional transfer matrix. Subsequently, the sound absorption coefficient was calculated using the transfer matrix method and was compared with the experimental results. In the experiment, a two-microphone impedance tube was used to measure the sound absorption coefficient of the test samples. We attempted to perform a simple yet accurate estimation using these procedures. The theoretical analysis values exhibited a similar tendency to that of the experimental values.

DOI： 10.3397/1/376911

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

This article focuses on the theoretical analysis and experiment of a small plate vibration sound-absorbing device with a clearance and without surrounding restriction. Generally, a plate vibration sound-absorbing device absorbs sound in a frequency range lower than that of porous material, which is used as a sound-absorbing material, and its sound absorption coefficient is small. Furthermore, note that the plate is fixed at the periphery in a conventional plate vibration sound-absorbing device. Hence, when the plate is small, vibration barely occurs and effective sound-absorbing effect is not obtained. Given that the plate vibration sound-absorbing device has a restriction wherein a particular size of plate is required, it is primarily utilized for indoor finishing considering the architectural acoustics, and finding applications for small-sized machines has been challenging. Theoretical values in this work are calculated assuming that the clearance and back air layer for the small plate vibration sound-absorbing device constitute a Helmholtz resonator. Furthermore, experiments were conducted to perform comparisons against the theoretical value. The theoretical analysis was conducted by connecting the clearance and back air layer in parallel with the plate portion in the electrical equivalent circuit. By performing the experiments using various parameters, the sound absorption characteristics of the proposed plate vibration sound-absorbing device were determined. If the clearance is smaller than the boundary layer thickness, then the conventional resistive end correction cannot be applied.

DOI： 10.3397/1/37693

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

In this study, the sound absorption characteristics of lightweight powders with a particle size on the order of tens of micrometers have been investigated. Herein, to theoretically determine the sound absorption coefficient of a fine lightweight powder in the longitudinal vibration mode, it was assumed that the powder was continuum and could be treated as a multiple degree-of-freedom damping vibration system. In addition, the acoustic impedance was calculated by assuming proportional viscous damping to determine the sound absorption coefficient. Finally, the theoretical and experimental values were compared. With the presented theoretical analysis, values close to the experimental results were obtained. Among the three calculated values based on proportional viscous damping, i.e., Rayleigh damping, rigidity proportional damping, and mass proportional damping, the results for Rayleigh damping were the closest to the experimental values.

DOI： 10.1121/1.5126951

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The sound absorption coefficient of thin tubes with a honeycomb-corrugated structure was estimated via theoretical analysis assuming the dimensions of the tube and the known physical properties of air. This analysis yields a propagation constant and characteristic impedance, which can be modeled as a one-dimensional transfer matrix. The sound absorption coefficient is then calculated by the transfer-matrix method and the results of comparison with the experiments are reported. The corrugated clearance was divided into elements for which approximations that assumed the clearance between two planes and took into account the perimeter and cross-sectional area of each element were considered. The theoretical value of the sound absorption coefficient obtained using this method was shown to be in good agreement with the experimental results. The experimental value of the sound absorption coefficient was larger than the theoretical value in the previous method in the analysis wherein each divided element was approximated by the distance between two planes taking into account the thickness and cross-sectional area of the clearance.

DOI： 10.1121/1.5089427

Web of Science

PubMed

researchmap

DOI： 10.7567/1347-4065/aaec10

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The present study focuses on a silencer built within the thick portion of a door edge and reports on the results of evaluating silencers by determining sound transmission loss via theoretical analysis and experiments on three types of silencers. The theoretical analysis involved determining the calculated values of sound transmission loss obtained using the transfer matrix method. The change in cross-sectional shape was analyzed by elemental division of the transfer matrix. Using the above, simulations were performed with respect to the optimum shape of the silencer. These theoretical analyses were then compared with the measurement results. Furthermore, the study includes the results of an experiment that attempted to restrain the dip in sound transmission loss by adding a non-woven fabric to the opening of the silencer. In a side branch silencer with an increasing shape wherein the longitudinal cross-section is a linear or an exponential function, the peak of the transmission loss was shifted to the lower frequency side when compared with that in the case of a rectangular side branch silencer. Furthermore, in comparisons between the two, the sound attenuation peak frequency was lower in the case of the exponential shape. The resonance of the side branch was suppressed by adding a non-woven fabric to the opening of the side branch silencer. As a result, the peak and dip of sound attenuation were alleviated, and the sound attenuation characteristics could be adjusted.

DOI： 10.1121/1.5082301

Web of Science

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Acoustical Society of America  

Closely packed nested structure circular tubes form three types of clearances: circular clearances, concentric clearances, and longitudinal clearances. The cross-sectional shape of rice straw, including three types of clearances?circular clearances, concentric clearances, and clearances formed by three closely packed cylinders?is similar to that of the samples of the present study. Herein, the propagation constant and characteristic impedance of the circular, concentric, and longitudinal clearances surrounded by three cylindrical surfaces are treated as a transfer matrix. Then, by connecting these transfer matrices in parallel, a transfer matrix integrating these clearances is determined, and the sound absorption coefficient is calculated. Test samples that have three types of clearances are also created, and measure their sound absorption coefficients. The contributions of the concentric and circular clearances are significant because of the dimensions of the used tubes. The results of the calculations that took eccentricity into account revealed no significant impact on the sound absorption coefficient in wide-frequency range. The results of the calculations that took flexure int

DOI： 10.1121/1.5063348

Web of Science

PubMed

researchmap

その他リンク： https://asa.scitation.org/doi/abs/10.1121/1.5063348

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：FRONTIERS MEDIA SA  

Light-gated ion channels and transporters have been applied to a broad array of excitable cells including neurons, cardiac myocytes, skeletal muscle cells and pancreatic b -cells in an organism to clarify their physiological and pathological roles. Nonetheless, among nonexcitable cells, only glial cells have been studied in vivo by this approach. Here, by optogenetic stimulation of a different nonexcitable cell type in the cochlea of the inner ear, we induce and control hearing loss. To our knowledge, deafness animal models using optogenetics have not yet been established. Analysis of transgenic mice expressing channelrhodopsin-2 (ChR2) induced by an oligodendrocyte-specific promoter identified this channel in nonglial cells-melanocytes-of an epithelial-like tissue in the cochlea. The membrane potential of these cells underlies a highly positive potential in a K C -rich extracellular solution, endolymph; this electrical property is essential for hearing. Illumination of the cochlea to activate ChR2 and depolarize the melanocytes significantly impaired hearing within a few minutes, accompanied by a reduction in the endolymphatic potential. After cessation of the illumination, the hearing thresholds and potential returned to baseline during several minutes. These responses were replicable multiple times. ChR2 was also expressed in cochlear glial cells surrounding the neuronal components, but slight neural activation caused by the optical stimulation was unlikely to be involved in the hearing impairment. The acuteonset, reversible and repeatable phenotype, which is inaccessible to conventional gene-targeting and pharmacological approaches, seems to at least partially resemble the symptom in a population of patients with sensorineural hearing loss. Taken together, this mouse line may not only broaden applications of optogenetics but also contribute to the progress of translational research on deafness.

DOI： 10.3389/fnmol.2017.00300

Web of Science

PubMed

researchmap

記述言語：日本語   出版者・発行元：日本機械学会  

<p>In this article, we examined several longitudinal-sectional sizes of a silencer whose volume was limited by the thickness and aperture ratio of the ventilation door. We report the results of improvement in the sound attenuation properties of these shapes. As an evaluation method for the silencer, we measured transmission losses using an impedance measurement tube and calculated them on the basis of a theoretical analysis. The following results were obtained from the evaluation of the silencer using the measurement and calculation results and from the verification of the improved shape of a silencer and silencer array. For a side branch tube silencer with a 1/3 aperture ratio, assuming that it is installed into the ventilation door, we observed a side branch tube with an linear expanded longitudinal-sectional shape by improving the shape using the theoretical analysis of transmission losses. In addition, as a result of the experiment with a sample on the basis of the theoretical analysis, both the experimental and the theoretical analysis were in good agreement. Furthermore, the expanded shape of the longitudinal-section of the side branch tube decreased the frequency of the sound attenuation peak. It was found that a silencer with a combination of four of these silencers can be arrayed side-by-side in a ventilation door; this results in a flat transmission loss of more than 5 dB over a broad band.</p>

DOI： 10.1299/transjsme.16-00575

CiNii Article

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS  

An optical range finder system that relies on laser diodes' frequency noise, instead of intensity or frequency modulations, and its improvement in resolution are reported. The distance to the target is measured by calculating the cross-correlation of two signals reflected from the target and reference mirrors. These two signals are converted from the laser diodes' frequency noise signals by frequency/intensity converters, such as a Fabry-Perot etalon. We obtained the distance to the target by checking time lags between the target and reference beams at the highest correlation coefficient. We also measured the change in the correlation coefficient around the peak sampling point by adjusting the reference-path length, achieving a resolving power of +/- 3 mm. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.

DOI： 10.1117/1.OE.56.6.064101

Web of Science

researchmap

記述言語：日本語   出版者・発行元：日本機械学会  

本論文においては，稲藁を束ねた吸音構造を，音波入射方向に対して斜めに配置した吸音材料ならびに，自由場における垂直及び斜め入射吸音率についても併せて報告する．稲藁を垂直方向に配置した試料と，斜め方向に配置した試料のいずれにおいても，自由場での垂直入射吸音率は音響管による結果に近い．稲藁を垂直方向に配置した試料と，斜め方向に配置した試料のいずれにおいても，自由場での斜め入射吸音率の吸音ピークは垂直入射吸音率に比べて高周波数側にシフトし，吸音カーブは高周波数域において平坦になる．これらのことより，稲藁製吸音材料が入射面に細孔を有する吸音材料として機能していると考えられる．

DOI： 10.1299/transjsme.16-00344

CiNii Article

J-GLOBAL

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/transjsme/83/845/83_16-00344/_article/-char/ja/

記述言語：英語   出版者・発行元：公益社団法人 日本工学教育協会  

In 1996, when the Faculty of Engineering of Niigata University, Niigata Japan first set up its international student exchange program with Otto-von-Guericke-University, in Magdeburg, Germany, few students showed an interest in studying abroad. Twenty years later, the students' attitudes have changed. The number of students who express a desire to study abroad and have experienced the international conference has increased markedly. In this article, two directions of opportunities for students to start studying abroad are presented; one is short-term summer school program as a subject of general education to remove the students' barriers to go abroad, and the other is research-oriented students' exchange program.

DOI： 10.20549/jseeen.2017.0_31

CiNii Article

CiNii Books

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

A stable microwave source using frequency stabilized diode lasers was developed. The Doppler-free spectra of Rb atoms produced by saturated absorption spectroscopy were used to obtain highly-sensitive control signals and lock the frequency of diode lasers to it. The beat frequencies between two independently stabilized diode lasers were 1.2 GHz and 2.9 GHz. The fluctuations in beat frequencies were 40 kHz and 400 kHz respectively in the best stability.

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MDPI AG  

Co-application of acoustoelasticity and optical interferometry to residual stress analysis is discussed. The underlying idea is to combine the advantages of both methods. Acoustoelasticity is capable of evaluating a residual stress absolutely but it is a single point measurement. Optical interferometry is able to measure deformation yielding two-dimensional, full-field data, but it is not suitable for absolute evaluation of residual stresses. By theoretically relating the deformation data to residual stresses, and calibrating it with absolute residual stress evaluated at a reference point, it is possible to measure residual stresses quantitatively, nondestructively and two-dimensionally. The feasibility of the idea has been tested with a butt-jointed dissimilar plate specimen. A steel plate 18.5 mm wide, 50 mm long and 3.37 mm thick is braze-jointed to a cemented carbide plate of the same dimension along the 18.5 mm-side. Acoustoelasticity evaluates the elastic modulus at reference points via acoustic velocity measurement. A tensile load is applied to the specimen at a constant pulling rate in a stress range substantially lower than the yield stress. Optical interferometry measures the resulting acceleration field. Based on the theory of harmonic oscillation, the acceleration field is correlated to compressive and tensile residual stresses qualitatively. The acoustic and optical results show reasonable agreement in the compressive and tensile residual stresses, indicating the feasibility of the idea.

DOI： 10.3390/ma9020112

Web of Science

PubMed

researchmap

その他リンク： http://www.mdpi.com/1996-1944/9/2/112

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

In this study, we theoretically and experimentally explore the acoustic leak of an entire acoustic system as well as the various gap occurring between a gasket and flange. We conducted the first-ever fundamental research related to sound transmission loss through a narrow gap between a gasket and flange. In the experiments, we constructed pipeline elements, including the gap and the leakage path, in the impedance measurement tube. In the theoretical analysis, we replaced the fluid path, including the gap, with acoustic elements that comprise an electrical equivalent circuit. We then conducted the analysis using the transfer matrix method. To calculate the attenuation of sound waves propagating through the gap, we considered friction in association with viscosity, primarily in the boundary layers of the inner wall, to derive the characteristic impedance and propagation constant. The trends between the calculated and the actual experimental values for transmission loss in the entire acoustic system coincided enough with regard to a large gap size range between 0.01 and 0.2 mm. Furthermore, the transmission loss linearly increased with the decreasing logarithm of gap for the calculated regions. Furthermore, the theoretical analysis and experimental results show agreement for incline gap conditions between the gasket and flange. The maximum gap also greatly affects the acoustic transmission loss for the inclined gaps. This was confirmed both by the experimental and the calculated values. We consider that these results provide fundamental acoustic knowledge specific to the narrow gap between the gasket and flange in an acoustic system.

DOI： 10.1299/jamdsm.2016jamdsm0067

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER-VERLAG BERLIN  

This paper reports a natural ventilation silencer for an animal cage having considerable sound insertion loss. Many veterinary hospitals face a serious problem that hospitalized animals are stressed from the barks of other dogs in the hospital. To address this problem, a solution that barely affects caged dogs' health is required. We attempted to use a silencer with sound insertion loss by attaching it to an opening side of the cage. We constructed the tested prototype silencers by using the resonance of a rectangular room and a nonwoven fabric. We measured the acoustic characteristics of the silencers that were attached to the real scale model of the animal cage. We also measured their insertion loss by considering the estimated frequency characteristics of the dogs' barking sound. The result shows that proposed silencers have more than 10 dB insertion loss; therefore, they can maintain respiratory environment of a caged dogs along with good visibility.

DOI： 10.1007/978-3-319-06986-9_16

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER-VERLAG BERLIN  

This paper reports a natural ventilation silencer for an animal cage having considerable sound insertion loss. Many veterinary hospitals face a serious problem that hospitalized animals are stressed from the barks of other dogs in the hospital. To address this problem, a solution that barely affects caged dogs' health is required. We attempted to use a silencer with sound insertion loss by attaching it to an opening side of the cage. We constructed the tested prototype silencers by using the resonance of a rectangular room and a nonwoven fabric. We measured the acoustic characteristics of the silencers that were attached to the real scale model of the animal cage. We also measured their insertion loss by considering the estimated frequency characteristics of the dogs' barking sound. The result shows that proposed silencers have more than 10 dB insertion loss; therefore, they can maintain respiratory environment of a caged dogs along with good visibility.

DOI： 10.1007/978-3-319-06986-9_16

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

This study focuses on acoustic silencers on indoor-use doors positioned in an array. In this paper, we discuss our studies of side branch silencers which are built in the ventilation door. By designing and fabricating a special attachment, we were able to attach silencers to the measurement tube that had larger cross sections than the impedance measurement tube. Using this attachment, we measured acoustic transmission losses for each of six different prototype silencers. By adding orifice silencer effects, we obtained transmission losses across a wide frequency range. However, attenuation decreased in frequency ranges below the attenuation peak of the side branch tubes. A wedge-shaped longitudinal cross section for the side branch tubes can double the length of the silencer and develop lower-frequency attenuation effects, while maintaining the same volume. This wedge-shaped side branch tube is suitable for a long silencer placed side by side in an array formation We performed theoretical analyses of acoustic transmission losses of silencers using the transfer matrix method based on a one-dimensional wave equation. We performed element decomposition on the transfer matrix for silencers with side branch tubes with a wedge-shaped longitudinal cross section. We obtained calculated results that were sufficiently valid compared to our experimental measurements.

DOI： 10.1299/jamdsm.2015jamdsm0028

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/9/3/9_2015jamdsm0028/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

In this paper, we propose a louver with a simple structure and a high aperture ratio. A louver element with a sound attenuating structure composed of layered two flat rectangular tubes, each of which is wedge-shaped with thickness decreasing toward the closed end, was constructed and experimentally and theoretically analyzed. Samples having more basic structures were also constructed and compared. In the theoretical analysis, the sound attenuation characteristics of a louver element were clarified considering sound attenuation in the clearance between two planes, as is typically observed in the flat rectangular tubes furnished in the louver element. To consider the sound attenuation due to the viscosity of the air in the rectangular tube, the propagation constant and characteristic acoustic impedance were derived using the Navier-Stokes equations, etc. Further, the sound transmission loss was calculated by the transfer matrix method. The tendency of the theoretical values in consideration of the attenuation of sound wave roughly agreed with the experimental values. Note that the attenuation of sound wave is evident in a thin or wedge-shaped tube and has to be considered in the theoretical analysis. The number of flat rectangular tubes was doubled without increasing the thickness of a louver element. The structure is useful as a louver slat because sound attenuation is achieved in a wide frequency range while maintaining a high aperture ratio.

DOI： 10.1299/jamdsm.2015jamdsm0039

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/9/3/9_2015jamdsm0039/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

There are engineering benefits if we can predict the acoustic properties such as the sound absorption coefficient of a sound incident on the clearance of such an annular cross-section based on the geometric dimensions of the tubes and the physical properties of the gas. However, a successful theory for the sound absorption coefficient of narrow tubes of the abovementioned shapes has not yet been presented, and the comparison between experimental and theoretical values has not been made. Further, the propagation constant and characteristic impedance in the clearance in a double cylinder have not yet been derived in the cylindrical coordinate system or by other methods. Therefore, in this paper, the propagation constant and characteristic impedance were derived by approximating clearance of an annular cross-section with clearance between two parallel planes. And the sound absorption coefficient was calculated, then compared with experimental results. The theoretical values, according to this method, agreed well with the experimental values, and practically sufficient accuracy was obtained. It was experimentally confirmed that the eccentricity of a round bar in a circular hole does not appreciably influence the sound absorption coefficient. Even when this calculation method is applied to a circular hole, the results agree with the theoretical and experimental values for the circular hole. Therefore, this method is effective even if the diameter of the internal cylinder is considerably smaller than that of the external cylinder.

DOI： 10.1299/jamdsm.2015jamdsm0040

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/9/3/9_2015jamdsm0040/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

We conducted a study related to sound absorbing materials created by folding thin material in the shape of a Japanese folding fan. In order to conduct a calculation of the shape of a clearance in the folding fan-shaped test sample, we performed an approximation of element decomposition in both the incidence direction of the sound wave and the lateral direction. In a theoretical analysis, we considered sound wave attenuation due to boundary layer friction in the clearance between two surfaces. We compared experimental and calculated values for the sound absorption coefficient. Trends in both matched closely. Errors in the calculated values for large clearances could be attributed mainly to irregularity in the size of the clearances. Frequency shift of the calculated values for small clearances were due to errors in estimating the sound attenuation. Sound absorbing structures shaped like a folding fan possess sound absorption characteristics are similar to the wedge-shaped sound absorbing structures shown in previous reports. This was also shown in calculated values based on theoretical analysis. In cases with an appropriate back air space, sound absorption peak frequencies decreased relative to cases without a back air space, and sound absorption characteristics were superior across a wide frequency range.

DOI： 10.1299/jamdsm.2015jamdsm0062

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/9/5/9_2015jamdsm0062/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

This study estimates the sound-absorption coefficient and transmission loss for the dimensions of clearances among the close-packed cylinders by theoretical analysis and compares these estimates with experimental values. In the analysis, we performed an elemental breakdown of the clearance configuration, and then approached each element as the clearance between two planes. Considering the effects of sound wave attenuation in each element of clearance, we found the propagation constant and characteristic acoustic impedance using three-dimensional analysis. By connecting these elements in parallel, we treated them as a one-dimensional transfer matrix. We then calculated the sound-absorption coefficient and transmission loss through the transfer matrix method. No sound-absorption coefficient could be obtained with calculations that did not account for attenuation. In addition, calculations that approached the clearance as an equivalent circle and a triangle did not match experimental values well. On the other hand, calculations using the method that accounted for clearance shape, that is the method used in this study, closely matched experimental values. Estimations of transmission loss expressed all clearances by connecting their transfer matrices in parallel. In calculations, these estimations did not account for attenuation, and the falling curve for transmission loss greatly diverged from experimental values. In the three calculations that accounted for attenuation, the falling segment of transmission loss showed frequency characteristics that were close to experimental values. Calculations through the methods that accounted for clearance shapes and that analyzed clearance as an equivalent triangle also had peak transmission loss values that closely matched experimental values.

DOI： 10.1299/jamdsm.2015jamdsm0065

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/9/5/9_2015jamdsm0065/_pdf

記述言語：日本語   出版者・発行元：日本機械学会  

旋削フランジと金属ガスケット間の密封特性を評価する際には，接触表間の平均すきまを基に漏れ量を見積もることが一般的であった．しかし，複雑な漏れ経路を平均すきまへと単純化するので，定性的に漏れ量を予測できても，定量的な予測は困難であった．本研究では，広視野レーザ顕微鏡を用いて，接触面全面の接触状況を観察できるようにした．旋削フランジの旋削峰がすべてガスケットに接触する臨界接触圧力以上では，旋削溝に沿って漏れ流れが生じると仮定することで，漏れ量を定量的に予測することができた．さらに，臨界接触圧力以下のところでも，観察画像から漏れ経路を特定できるので，ある程度精度良く漏れ量を予測することができた．

DOI： 10.1299/transjsme.2014dsm0173

CiNii Article

J-GLOBAL

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/transjsme/80/814/80_2014dsm0173/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Science Publishing Group  

This paper reports a natural ventilation silencer for an animal cage having considerable sound insertion loss. Many veterinary hospitals face a serious problem that hospitalized animals are stressed from the barks of other dogs in the hospital. To address this problem, a solution that barely affects caged dogs’ health is required. First, we estimated aperture ratio of the silencer device which was considered by physiological sustainability of dog. Next, we attempted to use a silencer with sound insertion loss by attaching it to an opening side of the cage. We constructed the tested prototype silencers by using the resonance of a rectangular room and a nonwoven fabric. We measured the acoustic characteristics of the silencers that were attached to the real scale model of the animal cage. We also measured their insertion loss by considering the estimated frequency characteristics of the dogs’ barking sound. The result shows that proposed silencers have more than 10 dB insertion loss; therefore, they can maintain respiratory environment of a caged dogs along with good visibility.

DOI： 10.11648/j.ijmea.20140201.14

CiNii Article

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

This paper discusses a noise reduction structure with a thin Helmholtz resonator array integrated in louver elements. Using theoretical analysis, we derived the propagation constant and characteristic acoustic impedance with consideration for sound wave attenuation in the clearance between two planes for a thin cavity within the louver. The experiments with variation in three conditions were also performed: number of necks, internal thickness of the cavity, and number of partitions. Another experiment was conducted to verify that sound reduction characteristics change depending on the number of holes. The results closely matched with those calculated with consideration for attenuation, demonstrating the validity of the theoretical analysis. With respect to changes in the internal thickness of the cavity, experimental results showed that attenuation increased for clearances of 2 mm, causing significant differences in the sound reduction characteristics. At clearances of 8 mm, there was almost no attenuation in the clearance. Louvers with thin internal dimensions, in which holes diameter equal to the internal thickness of the cavity had been formed, created a larger effect than those with normal open end correction length. This resulted in a reduction in sound reduction frequency. Additionally, when cavities seen from the neck are created on the end face of the louver element as acoustic tubes, the properties of the acoustic tubes are added to the properties of the air spring. This achieved a significant reduction in the sound reduction peak frequency without increasing the volume of the cavity.

DOI： 10.1299/jamdsm.2014jamdsm0022

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/8/3/8_2014jamdsm0022/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

We investigated the sound absorption coefficient within a sound-absorbing structure made of layered clearances between two planes. We discussed the experimental results from the existing literature and conducted a theoretical analysis on several different sound-absorbing structures that take into account the viscosity of the boundary layer at the clearances. First, we examined the case of thin sheets placed in parallel. Then, we examined the case where the size of the clearance continuously changed perpendicular to the direction of incidence of the sound waves. Subsequently, we examined the case where the clearance continuously decreased in the direction of incidence of the sound waves. In latter two cases, the transfer matrix used in the calculations was divided into elements perpendicular or coincident to the direction of incidence of the sound waves and the size of the clearance for each element was changed in a stepwise fashion. We then calculated the sound absorption coefficients for various structures and dimensions and observed that the calculated and experimental data agreed well. On the basis of the calculation simulation, the differences between the calculated and experimental absorption coefficient data were attributed mainly to the changes in the flexure of the sheet materials. The proposed calculation methods will be useful in determining the absorption coefficient of such shapes, and in the design of sound-absorbing materials that use such shapes.

DOI： 10.1299/jamdsm.2014jamdsm0036

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/8/3/8_2014jamdsm0036/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ASME  

To quantitatively predict the leakage rates of static metal seals, it is important to observe the real contact area at seal surfaces because the leakage path consists of the noncontact portions between the flange and gasket surfaces. In a previous study, we observed the real contact situation using a thin polymer film 1 mu m in thickness. In the present study, we observed the real contact area on gasket surfaces using a laser microscope with a wide field of view. With this method, observation time over the whole gasket surface could be greatly reduced compared with conventional methods. The observations indicated that the leakage paths on the gasket surfaces were in the radial direction perpendicular to a lathe-turned groove and the circumferential direction along the groove. As the closing loads increased, the leakage paths in the radial direction disappeared and only the leakage path in the circumferential direction remained. When the closing loads increased further, the widths of the leakage paths at both the inside and outside on the gasket surface became narrower. The critical contact pressure where the leakage paths in the radial direction disappear was determined from the observation of the contact surface of the gasket. The leakage rates obtained from the experiments showed good agreement with the calculated values under the assumption of laminar flow along the turned groove over the critical contact pressure.

DOI： 10.1115/1.4024781

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS  

We describe a method of generating physical random numbers by means of a diode laser that has an extremely wide-band frequency-noise profile. Fluctuations in the laser frequency affect the intensity of the light transmitted through the optical frequency discriminator, detected thereafter as random fluctuations. This allows us to simultaneously generate 8 random bit streams, due to the parallel processing of 8-digit binary numbers sampled by an 8-bit analog-to-digital converter. Finally, we generated physical random numbers at a rate of 3 Gbit/s, by combining one data stream with another stream that is delayed by 2 ms, by exclusive-OR. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. [DOI: 10.1117/1.OE.52.1.014302]

DOI： 10.1117/1.OE.52.1.014302

Web of Science

researchmap

その他リンク： http://SPIEDigitalLibrary.org/oe

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本機械学会  

細穴の集合体は管路中の触媒等，吸音や透過損失を主たる目的としない場合でも，各所に見られる．このような細穴の集合体について幾何学的な寸法のみを用いて，吸音率や透過損失を正確に推定することは重要である．そこで著者等は，理論的な推定法の開発を試み，2マイクと4マイクインピーダンス管によって行われた実験結果と比較する事で，その有効性を検証した．最初に，精密な推定のために，計算には，音波の減衰を考慮した二次元円柱座標系の解析に基づいた，細管内の伝搬定数と特性インピーダンスを適用した．次に，二次元の解析を基にした正確な伝搬定数と特性インピーダンスを，軸方向の一次元の伝達マトリックスへ，変換・導入をした．これにより，消音器の設計などで一般的な，一次元の伝達マトリックスを用いて，簡易なプロセスにより精密な推定が可能になった．

DOI： 10.1299/kikaic.79.4164

Scopus

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/kikaic/79/807/79_4164/_pdf

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

開口率が高い薄板のルーバにおける音響透過損失は一般に小さい．本研究は，消音構造を持ったルーバに関するものである．細管要素を並べた薄板をルーバ羽根とした場合，高い開口率を維持したアレイ消音器を構成出来る．このルーバについて，いくつかの形状を試作し，実験および理論解析を行った．まず，4マイクロホンインピーダンス測定管を用い，透過損失の測定を行った．また，伝達マトリックス法による透過損失の理論値を算出した．薄板に内装された細管要素内の音波の減衰は無視出来ないため，理論解析では二次元問題から導かれた伝搬定数と特性インピーダンスを適用した．透過損失の実験値と理論値を比較し，消音特性の検証を行った．

DOI： 10.1299/kikaic.79.2817

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

In this paper fundamental sound absorption characteristics of expanded polystyrene beads with several geometries are reported when they are packed in some thick layers with and without back air space. The normal incidence sound absorption coefficients, which were obtained by the experiments using two-microphone impedance tube, were evaluated comparing to theoretical estimations. Experimental data were also compared to the similar conditions but hard material particles like glass beads whose acoustic property was investigated by Sakamoto et. al. in a preceding study. Then following results were obtained; packed layer with expanded polystyrene beads has almost equal sound absorption coefficient to the similar layer with hard and solid material: numerical estimation of sound absorption coefficient is valid enough except for the case having large back air space: lowering peak frequency of sound absorption coefficient is available by overfilling and compressing particles. The authors also consider that applying soft, light, and low cost material to the sound absorbing structures is very meaningful. Because human damage caused by falling of wall and ceiling panel of buildings is avoidable particularly under an earthquake attack.

DOI： 10.1299/jamdsm.7.677

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/7/4/7_677/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS  

Sound transmission loss is relatively small in thin louver boards with a high aperture ratio. This study investigated louver elements with a sound attenuating function. Using narrow tubes, an array silencer was built into composite louver boards and a high aperture ratio was maintained. Several constructions for such louvers were prototyped, measured, and analyzed theoretically. Sound transmission loss was measured using four-microphone impedance tube. Then, sound transmission loss was calculated by a transfer matrix based on one-dimensional axial coordinate system analysis. The attenuation of sound in tubes should be calculated because a thin louver board must comprise narrow tubes. Therefore, an accurate propagation constant and a characteristic impedance based on two-dimensional analysis were introduced to enable theoretical analysis. The calculation results, including attenuation, and the experimental results had good coincidence. Moreover, the theoretical analysis confirmed that the silencer worked effectively and could be applied to silencer designs.

DOI： 10.1299/jamdsm.7.690

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/7/4/7_690/_pdf

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本機械学会  

二連のオリフィスの間の膨張部に不織布シートを組み合わせた消音器について、インピーダンス管を用いて消音器の透過損失を測定し、ディップの改善効果を示した。また等価回路網により不織布部分の音響系をモデル化し、透過損失の計算値を求めた。その結果、実験値と計算値の傾向は良く一致し、提案した音響モデルで不織布シート部分をある程度近似できる事を示した。

DOI： 10.1299/kikaic.79.3474

Scopus

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/kikaic/79/806/79_3474/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japan Society of Mechanical Engineers  

A large portion of patients of larynx cancer tekes total laryngectomy and loses their original voice consequently. Some ways to obtain substitute voice for total laryngectomees have been presented, however, each of them cannot conquer inconveniences, tone quality, extremely low tone, monotonousness etc. We invented very simple, small enough to be built in TE (tracheaesophageal) shunt valve but functional substitute voice that is driven by patient’s own expiration and its tone pitch can be controlled by expiratory pressure simultaneously. The new device has an outward-striking membrane as an oscillating valve and a set of piston-cylinder mechanism, which controls oscillator’s tension and alters pitch of sound. As results of performance experiments applied to the prototype model made as twice scale as an actual dimension, the device produces the lowest sound frequency of 205 Hz and pitch range of 374 cent being approximately proportional to driving air pressure between 0.8 and 2.2 kPa. It is said that normal pitch of female voice is around 210 Hz, thus we consider the possibility of the device as a new substitute voice was shown that contributes to improvement of total laryngecto

DOI： 10.1299/jamdsm.7.777

Web of Science

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/jamdsm/7/4/7_777/_pdf

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本機械学会  

二面間の隙間を利用した吸音構造について，種々の形状・寸法について吸音率を実験により求めた．その結果，以下のことが明らかとなった．境界層厚さとの兼ね合いにより，70μmまでは，二面間の隙間が小さいほど，吸音率は高く，吸音ピーク周波数は低周波数で得られる．隙間が奥行き方向に連続的に減少する場合，隙間が一定の場合と比較して優れた吸音率が得られ，また，吸音率の周波数特性におけるディップは改善される傾向にある．薄板材料の物量が同一の場合，扇子型吸音構造は，楔形吸音構造と同等の吸音性能を有する．

DOI： 10.1299/kikaic.79.4141

Scopus

researchmap

その他リンク： https://www.jstage.jst.go.jp/article/kikaic/79/807/79_4141/_pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japan Society of Mechanical Engineers  

In this paper, several diameter of solid glass spherical grain was dealt. Each diameter grain has the each characteristic impedance and the complex wave constant. At first, the characteristic impedance and the complex wave constant for each grain diameters were measured. Then, the normal incidence absorption coefficient of each grain diameters for arbitrary layer thickness can be calculated. Likewise, the normal incidence absorption coefficient for multilayer with different grain diameters and arbitrary thicknesses can be calculated. This calculation process is comparatively lengthy, so the experiments for real multilayer and the calculations were compared. Result of the calculations coincided to the experiments. Consequently, calculation result of normal incidence absorption coefficient for multilayer with different grain diameters is useful.

DOI： 10.1299/jee.7.12

CiNii Article

researchmap

その他リンク： https://www.jstage.jst.go.jp/browse/jee/7/1/_contents

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japan Society of Mechanical Engineers  

This paper describes sound quality changes caused by a sound aerodynamic failure in a micro-axial fan when applying acoustic diagnostic methods at a cooling fan motor assembly line. The aerodynamic failure sound was focused to a rotational fan blade tone and a blade passing noise with a change in the fan blade run-out. Experimentally obtained results clarified the correlation between the sound quality metrics (Sharpness, Roughness, Fluctuation strength, Tone-to-noise ratio) and the blade run-out. Furthermore, an acoustic diagnosis technique for fan blade run-out is proposed using an adaptive spectrum enhancer. This proposed acoustic diagnosis technique is used for an adaptive feedback algorithm using an internal model control architecture to extract an abnormal periodic signal including aerodynamic sound generated by a rotating micro-axial fan. The experimentally obtained results show that the blade passing sound signal with the blade run-out change was improved by about 10 dB using this adaptive feedback algorithm.

DOI： 10.1299/jee.7.1

CiNii Article

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 日本機械学会  

A large portion of patients of larynx cancer tekes total laryngectomy and loses their original voice consequently. Some ways to obtain substitute voice for total laryngectomees have been presented, however, each of them cannot conquer inconveniences, tone quality, extremely low tone, monotonousness etc. We invented very simple, small enough to be built in TE (tracheaesophageal) shunt valve but functional substitute voice that is driven by patient&#039;s own expiration and its tone pitch can be controlled by expiratory pressure simultaneously. The new device has an outward-striking membrane as an oscillating valve and a set of piston-cylinder mechanism, which controls oscillator&#039;s tension and alters pitch of sound. As results of performance experiments applied to the prototype model made as twice scale as an actual dimension, the device produces the lowest sound frequency of 205 Hz and pitch range of 374 cent being approximately proportional to driving air pressure between 0.8 and 2.2 kPa. It is said that normal pitch of female voice is around 210 Hz, thus we consider the possibility of the device as a new substitute voice was shown that contributes to improvement of total laryngectomees&#039; QOL particularly to female patients.

DOI： 10.1299/kikaic.78.3053

Scopus

CiNii Article

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japan Society of Mechanical Engineers  

In this paper, the problem in the CO2 infrared laser medical operation device that propagates the laser in the hollow optical fiber was dealt. There is risk of the accident of damaging by a fire when leak is opened in the hollow optical fiber, and the laser light is discharged outside. This study is the detecting method for the leak on hollow optical fiber by using the sound. A basic experiment concerning this method and comparison result between the theoretical analysis and the experiment are reported. The leakage of the narrow tube with large attenuation can be detected. The experiment was corresponding to the tendency to the theoretical analysis for the presence of the leakage and the change in the hole diameter. This method is inexpensive than the method of adding the optical device, it makes small hand peace, and doesn't ruin handling that is the advantage of the hollow optical fiber.

DOI： 10.1299/kikaic.77.2096

CiNii Article

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japan Society of Mechanical Engineers  

The porous material with continuous pore is useful for the sound absorbing material. In this research work, rice straw, rice husks, and buckwheat husks were dealt as a porous sound absorbing material that applied the biomass. About rice straw, geometrical condition of that was reproduced in the narrow tube of the simple structure, and the effect of absorbing sound of the tubule in the composite structure was verified. In the experiment, for the various thickness and the back air space were tested by using two microphone impedance tube, and the normal incidence sound absorption coefficient was measured. Moreover, the absorption coefficient was calculated from the acoustical constant obtained from the result of a measurement in a specific condition. And, these calculation values were compared with experiment values. As a result, it was shown to be able to estimate the absorption coefficient of the condition of the unmeasurement. As for rice straw, rice husks, and buckwheat husks, it has been understood it has a useful characteristic of absorbing sound. It leads to the fixation of the carbon, and even if the incineration processing is done, it is a carbon neutral.

DOI： 10.1299/jee.6.352

CiNii Article

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1299/kikaic.76.2545

Scopus

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 日本機械学会  

The porous material with continuous pore is useful for the sound absorbing material. In this research work, rice straw, rice husks, and buckwheat husks were dealt as a porous sound absorbing material that applied the biomass. About rice straw, geometrical condition of that was reproduced in the narrow tube of the simple structure, and the effect of absorbing sound of the tubule in the composite structure was verified. In the experiment, for the various thickness and the back air space were tested by using two microphone impedance tube, and the normal incidence sound absorption coefficient was measured. Moreover, the absorption coefficient was calculated from the acoustical constant obtained from the result of a measurement in a specific condition. And, these calculation values were compared with experiment values. As a result, it was shown to be able to estimate the absorption coefficient of the condition of the unmeasurement. As for rice straw, rice husks, and buckwheat husks, it has been understood it has a useful characteristic of absorbing sound. It leads to the fixation of the carbon, and even if the incineration processing is done, it is a carbon neutral.

DOI： 10.1299/kikaic.75.3223

Scopus

CiNii Article

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 日本機械学会  

In this paper, variation of airborne sound absorption coefficient for granular material with small quantity water is dealt. The granular matter under the test is solid glass spherical grain as diameter 1mm. The relationship between water content by volume and absorption coefficient for each thickness of layer is measured by experiments. And tortuosity as one of the Biot&#039;s parameters is also measured by ultrasonic. It was proved that peak frequency of absorption coefficient decreases as increasing of water content. The reason is that reduced virtual sound velocity makes effect of larger sample thickness. Result of this study is useful for expecting absorption coefficient of wet or liquid bonded granular matter.

DOI： 10.1299/kikaic.75.2515

Scopus

CiNii Article

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 日本機械学会  

This paper describes a sound quality change caused by a failure aerodynamic sound in a micro axial fan in order to apply an acoustic diagnosis at cooling fan motor assembly line. The failure aerodynamic sound is focused to a rotational fan blade tone and blade passing noise with fan blade run-out change. In this experimental result, a correlation between the sound quality metrics (Sharpness, Roughness, Fluctuation strength, Tone-to-noise ratio) and the blade run-out is cleared. In addition, an acoustic diagnosis technique for a fan blade run-out is proposed using an adaptive spectrum enhancer. This proposed acoustic diagnosis technique is used to adaptive feedback algorithm using internal model control architecture to extract a periodic abnormal signal including aerodynamic noise generated by rotating a micro axial fan. As the experimental results, the blade passing sound signal with the blade run-out change was improved about 10dB by using this adaptive feedback algorithm.

DOI： 10.1299/kikaic.75.1194

Scopus

CiNii Article

J-GLOBAL

researchmap

記述言語：日本語   出版者・発行元：一般社団法人 日本機械学会  

In this paper, several diameter of solid glass spherical grain was dealt. Each diameter grain has the each characteristic impedance and the complex wave constant. At first, the characteristic impedance and the complex wave constant for each grain diameters were measured. Then, the normal incidence absorption coefficient of each grain diameters for arbitrary layer thickness can be calculated. Likewise, the normal incidence absorption coefficient for multilayer with different grain diameters and arbitrary thicknesses can be calculated. This calculation process is comparatively lengthy, so the experiments for real multilayer and the calculations were compared. Result of the calculations coincided to the experiments. Consequently, calculation result of normal incidence absorption coefficient for multilayer with different grain diameters is useful.

DOI： 10.1299/kikaic.74.2240

CiNii Article

CiNii Books

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japan Society of Mechanical Engineers  

The attenuation characteristics of a slit resonator that combined the adaptive feedback ANC system at a ventilation aperture of the package for leakage noise is investigated. The discrete tones radiated from an AC axial flow fan are controlled by DSP using Filtered-X Least Mean Square algorithm. The attenuation is found at the range of: 3<i>dB</i>-14<i>dB</i> with circular slit resonator, 2<i>dB</i>-15<i>dB</i> with elliptic slit resonator. Results of measurement show that the proposed system can achieve TNR(Tone to Noise Ratio) and PR(Prominence Ratio) under threshold effectively.

DOI： 10.1299/jee.2.470

CiNii Article

researchmap

その他リンク： http://orcid.org/0000-0002-5745-1668

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本機械学会  

The attenuation characteristics of a slit resonator that combined the adaptive feedback ANC system at a ventilation aperture of the package for leakage noise is investigated. The discrete tones radiated from an AC axial flow fan are controlled by DSP using Filtered-X Least Meane Square algorithm. The attenuation is found at the range of : 3 dB～14 dB with circular slit resonator, 2 dB～15 dB with elliptic slit resonator. Results of measurement show that the proposed system can achieve TNR (Tone to Noise Ratio) and PR (Prominence Ratio) under threshold effectively.

DOI： 10.1299/kikaic.71.327

CiNii Article

CiNii Books

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本機械学会  

This paper deals with the development of a new method for measurement of the height for granular material in a cylinder. For monitoring of automated filling processes of cartridges in a series production a new measurement method was developed which allows to detect rapidly incorrect products and to improve the process capability by the use of this method. The aim of this research work is to measure the level of granular material in a cartridge without contacting the material. The material is the mixture of the solid particles and air. The material is assumed as the porous media from the viewpoint of acoustics. As that, the inside of the cartridge, which is filled with granular material, is the acoustic system including porous media. The measuring method used the relationship between amount of granular meterial in the cartridge and the characteristics of the transfer function of the acoustic system is developed. The acoustic characteristic of the granular material, which is used for the theoretical analysis was also measured.

DOI： 10.1299/kikaic.70.679

CiNii Article

CiNii Books

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本機械学会  

This paper deals with the development of a new method for determination of powder form materials in plastic bag by sound. It is useful to determine the kind of powder form materials in the opaque plastic bag without open or contact. This detector utilizes the variation of the amplitude of the frequency response within entire acoustic system. The incident impedance of powder form materials varies with the diameter of particles and so on. For contactless determination, small distance gap between face of detector and plastic bag is adopted. Characteristic acoustic impedance and complex wave number are measured by the transfer function method. These measured parameters of powder form materials are introduced into theoretical analysis. The trends of the experiments and theory show good coincidence.

DOI： 10.1299/kikaic.69.42

CiNii Article

CiNii Books

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本機械学会  

This paper describes insulation characteristics of slit resonator that a single channel ANC system for silencing leakage noise at ventilation aperture of package. The circular slit resonator composed of thin air layer that is radial expansion with very short axial length was set up package wall. The circular thin air layer is driven by one to four speakers that are controlled using Filtered-X-LMS algorithm to minimize sound power at error microphone. The experimental results show that the noise reduction region spreads to the high frequency side, as the slit depth decreases. The noise reduction quantity increases, as the slit width widens. Visualization of SPL and phase on the circular slit resonator indicate that the noise reduction mechanism is the interference of control sound and noise.

DOI： 10.1299/kikaic.68.3122

CiNii Article

CiNii Books

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本機械学会  

This paper deals with the development of a new method for detecting the number of cloth without contact. It is necessary to detect one or plural number of sheets to avoid mishandling. This detecting sensor utilizes the variation of the phase of the transfer function within entire acoustic system. The incident impedance of sheets varies with the number of sheets. Characteristic acoustic impedance and complex wave number define peculiar and most fundamental characteristics of the material. It is useful for the detection of the number of cloth to know characteristic impedance of cloth. So that, we tried to measure characteristic impedance and wave number. The measured impedance of sheets by the transfer function method was introduced into theoretical analysis. The results of the experiments and theoretical analysis show fairly good coincidence

DOI： 10.1299/kikaic.67.1276

Scopus

CiNii Article

J-GLOBAL

researchmap

記述言語：日本語   出版者・発行元：一般社団法人 日本機械学会  

DOI： 10.1299/jsmehs.2000.37.147

CiNii Article

researchmap

記述言語：日本語  

DOI： 10.1299/kikaic.64.986

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人日本機械学会  

In this paper, we discuss the development of a new noncontact method for determining cylinder configurations using sound phase delay, In order to improve the accuracy of the measurements, the effect of the cavity in which the cylinder is placed has been studied. When the cylinder is placed near a side wall of the cavity, the phase delay angle increases, particularly for cylinders with odd periodic deflection. Thus, by varying the gap between the cylinder and the side wall, it is possible to determine the cylinder configuration even if the deflections are small. We propose a new method, in which the influence of noise is avoided by measuring the noise interference using a pair of microphones in the cavity.

DOI： 10.1299/kikaic.63.1989

CiNii Article

CiNii Books

J-GLOBAL

researchmap

記述言語：日本語   出版者・発行元：一般社団法人 日本機械学会  

DOI： 10.1299/kikaic.62.4250

CiNii Article

CiNii Books

J-GLOBAL

researchmap

その他リンク： http://www.jstage.jst.go.jp/article/kikaic1979/62/603/62_603_4250/_pdf

記述言語：日本語  

DOI： 10.1299/kikaic.62.949

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1299/kikaic.61.1516

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS SANSHIN HOKUSEI BLDG  

This paper deals with a newly developed underwater displacement sensor utilizing the acoustic resonant frequency of water in a submerged pipe. Both ends of the pipe are closed. A speaker to generate sound is fixed on the end of the pipe with the reflector at the other end. A piezoelectric ceramic is used as a speaker. Sweeping signal is radiated from the speaker to the water column in the pipe. The sound pressure takes the largest value at the resonant frequency. The displacement of the reflector which is inserted from the other end of the pipe by the plunger, corresponds to the length of the water column. The displacement of the reflector has good correspondence to the resonant frequency of the water column. It is found from the experiment that it is possible to measure accurately underwater displacement using this sensor.

DOI： 10.1299/jsmec1993.38.42

Web of Science

researchmap

記述言語：日本語  

DOI： 10.1299/kikaic.60.994

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

researchmap

記述言語：日本語   出版者・発行元：日本機械学会  

This paper deals with the development of a new detecting method of a number of sheets without contact. For example, in a cash dispenser paper sheets are transferred one by one and counted synchronously. So it is necessary to detect one or a plural number of sheets to avoid mistransferring. Hitherto, the contact measuring method has been used for detecting the transference of sheets. This noncontact sensor utilizes the variations of frequency response of the whole acoustic system of the sensor with sheets which are set near the sensor. The impedance of sheets varies with its number. The number of sheets has shown good correspondence with the resonant frequency and frequency response of the acoustic system. An electrical analogy is adopted for theoretical analysis of the acoustic system. The results of the calculation and experiments coincide significantly. It is possible to detect the number of sheets within a very short time period by means of variations of the frequency response.

DOI： 10.1299/kikaic.59.819

CiNii Article

CiNii Books

J-GLOBAL

researchmap

その他リンク： http://hdl.handle.net/10191/5797

記述言語：日本語   出版者・発行元：日本機械学会  

This paper deals with a newly developed underwater displacement sensor utilizing the acoustic resonant frequency of water in a submerged pipe. Both ends of the pipe are closed. A speaker to generate sound is fixed on the end of the pipe with a reflector at the other end. Piezoelectric ceramic is used as a speaker. A sweep signal is radiated from the speaker to the water column in the pipe. The sound pressure takes the largest value at the resonant frequency. The displacement of the reflector which is inserted from another end of the pipe by a plunger, corresponds to the length of the water column. The displacement of the reflector has good correspondence to the resonant frequency of the water column. It is found from the experiment that it is possible to accurately measure underwater displacement, using this sensor.

DOI： 10.1299/kikaic.59.587

CiNii Article

CiNii Books

J-GLOBAL

researchmap

その他リンク： http://hdl.handle.net/10191/5909

記述言語：日本語  

DOI： 10.1299/kikaic.58.3259

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS SANSHIN HOKUSEI BLDG  

A new method of measuring displacement by means of variations of sound frequency and length of an air column in a stopped resonant pipe has been investigated. In this study, a speaker was used as the sound-generating source instead of the air jet, which was used for the feedback excitation mechanism on the edge instrument. This paper deals with a new kind of displacement sensor using an electric feedback circuit. A sweep signal is radiated from the speaker through the small hole which is opened on one end of the closed resonant pipe, toward the inside of the air column. The sound pressure takes the largest value at the resonant frequency. The displacement of the plunger which is inserted from the other end of the pipe corresponds to the length of the air column. Thus, the displacement of the plunger corresponds well to the resonant frequency of the air column. The phase-locked loop device is adopted for stability of the resonance and frequency.

DOI： 10.1299/jsmec1988.35.9

Web of Science

researchmap

記述言語：日本語   出版者・発行元：日本機械学会  

A new displacement measuring method using variations in sound frequency and length of an air column in a closed resonant pipe has been investigated. This noncontact displacement sensor is oscillated by the feedback loop, which is composed of a speaker, microphone and phase-locked loop. The sound pressure takes the largest value at the resonant frequency. The displacement of the measuring object corresponds to the impedance of one end of the air column. Thus the displacement of the measuring object has good correspondence to the resonant frequency of the acoustic system. The original resonant point is measured by transfer function from the FFT analyzer. An electrical analogy is adopted for theoretical analysis of the acoustic system. The results of the calculation and experiments coincide significantly.

CiNii Article

CiNii Books

J-GLOBAL

researchmap

記述言語：日本語   出版者・発行元：日本機械学会  

管内空気柱の共鳴周波数は長さに対応する事を利用して管の長さを測定する方法を考案した。被測定管内に音波を放射し、マイクロホンにより拾った信号の周波数成分をフィードバックすることにより共振周波数において強力に発振させ、共振点を検出する。本測定法は、管が地中や液体中などに埋設されている場合や曲がり管の測定も可能である。

DOI： 10.1299/kikaic.57.2217

CiNii Article

CiNii Books

J-GLOBAL

researchmap

その他リンク： http://hdl.handle.net/10191/5793

記述言語：日本語   出版者・発行元：日本機械学会  

両端閉口管内に音波を入れ管内音圧が空気柱長さに対応した共振周波数で最大になる事を利用し、電気的フィードバックループを構成し発振させる変位センサにおいて、電気的等価回路により、音響系の理論解析を行い実験結果と比較した結果、両者はよく一致し、等価回路の妥当性が確認された。

DOI： 10.1299/kikaic.57.780

CiNii Article

CiNii Books

J-GLOBAL

researchmap

その他リンク： http://hdl.handle.net/10191/5791

記述言語：日本語   出版者・発行元：日本機械学会  

A new measuring method of displacement by means of variations of sound frequency and length of air column in a closed resonant pipe has been investigated. In this paper, a speaker is used as a sound generating source in stead of air jet for the feedback excitation mechanism on the edge instrument. This paper deals with a new kind of displacement sensor using a electric feedback circuit. A sweep signal is radiated from the speaker through the small hole at one end of the closed resonant pipe toward inside of the air column. The sound pressure takes the largest value at the resonant frequency. The displacement of the plunger which is inserted from other end of the pipe, corresponds to the length of the air column. So, the displacement of the plunger makes good correspondence to the resonant frequency of the air column. The phase locked loop devise is adopted for stability of the resonation and frequency.

DOI： 10.1299/kikaic.56.2562

CiNii Article

CiNii Books

J-GLOBAL

researchmap

その他リンク： http://hdl.handle.net/10191/5789

記述言語：日本語   出版者・発行元：日本機械学会  

一端閉口管の開口端に圧縮空気を吹き付けて音響を発生させ、空気柱長さと周波数を対応させた変位センサは、犬笛や一端閉口のエアリード楽器と同一のフィードバック発音機構を持つ。この観点から発音機構を解析し、等価回路を導き、音響インピーダンス、四端子網の定数を導入した。解析結果は実験結果とよい一致を見せ、解析の妥当性が確認された。

DOI： 10.1299/kikaic.56.435

CiNii Article

CiNii Books

J-GLOBAL

researchmap

その他リンク： http://hdl.handle.net/10191/5781

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC MECHANICAL ENGINEERS SANSHIN HOKUSEI BLDG  

DOI： 10.1299/jsmec1988.31.727

Web of Science

researchmap

記述言語：日本語   出版者・発行元：日本機械学会  

一端閉口管の開口端に圧縮空気を吹き付け音響を発生させ、管内空気柱の長さを他端から差し込んだプランジャの変位に対応させることにより、測定物変位を音響周波数に変換する変位センサを開発した。またジェットの存在により起こる周波数のずれの性質を、ジェット位相進角との関係を用いて明らかにした。

DOI： 10.1299/kikaic.54.651

CiNii Article

CiNii Books

J-GLOBAL

researchmap

その他リンク： http://hdl.handle.net/10191/5775

開催年月日： 2021年

記述言語：日本語  

researchmap

開催年月日： 2021年

記述言語：日本語  

researchmap

開催年月日： 2020年

researchmap

開催年月日： 2020年

記述言語：日本語  

researchmap

開催年月日： 2020年

記述言語：日本語  

researchmap

開催年月日： 2020年

記述言語：日本語  

researchmap

開催年月日： 2020年

記述言語：日本語  

researchmap

開催年月日： 2019年3月

記述言語：日本語  

researchmap

開催年月日： 2019年3月

記述言語：日本語  

researchmap

開催年月日： 2019年3月

記述言語：日本語  

researchmap

開催年月日： 2019年

記述言語：日本語  

researchmap

開催年月日： 2019年

記述言語：日本語  

researchmap

開催年月日： 2019年

記述言語：日本語  

researchmap

開催年月日： 2018年3月

記述言語：日本語  

researchmap

開催年月日： 2018年3月

記述言語：日本語  

researchmap

開催年月日： 2018年3月

記述言語：日本語  

researchmap

開催年月日： 2018年3月

記述言語：日本語  

researchmap

開催年月日： 2018年3月

記述言語：日本語  

researchmap

開催年月日： 2018年3月

記述言語：日本語  

researchmap

開催年月日： 2018年3月

記述言語：日本語  

researchmap

開催年月日： 2018年1月

© INTER-NOISE 2018 - 47th International Congress and Exposition on Noise Control Engineering: Impact of Noise Control Engineering. All rights reserved. It was reported the use of sound-absorbing materials, specifically sound-absorbing structures of bundled rice straws, that are oblique arranged incident to the sound waves. In addition, we investigated the normal and oblique incident sound-absorption coefficients of sound-absorbing structures made of bundled rice straws in free space. In this study, we placed sound-absorbing structures made of bundled rice straws at an angle against the direction of the thickness in order to elongate the rice-straw element without increasing the apparent thickness. We then experimentally investigated the increase in sound absorption in the low-frequency range. For test samples with rice straws arranged both in the normal direction and in the oblique manner, the sound-absorption peak of the oblique incident sound-absorption coefficient in free space was shifted to the high-frequency side compared with that of the normal incident sound-absorption coefficient and the sound-absorption curve became flat in the high-frequency range. We demonstrated that the use of an oblique arrangement of rice straws inside acoustic tubes and in free space can improve the sound absorption in low-frequency range without increasing the apparent thickness of the material.

researchmap

開催年月日： 2018年

researchmap

開催年月日： 2018年

記述言語：英語  

Not so long ago, pseudo random numbers generated by numerical formulae were considered to be adequate for encrypting important data-files, because of the time needed to decode them. With today's ultra high-speed processors, however, this is no longer true. So, in order to thwart ever-more advanced attempts to breach our system's protections, cryptologists have devised a method that is considered to be virtually impossible to decode, and uses what is a limitless number of physical random numbers. This research describes a method, whereby laser diode's frequency noise generate a large quantities of physical random numbers. Using two types of photo detectors (APD and PIN-PD), we tested the abilities of two types of lasers (FP-LD and VCSEL) to generate random numbers. In all instances, an etalon served as frequency discriminator, the examination pass rates were determined using NIST FIPS140-2 test at each bit, and the Random Number Generation (RNG) speed was noted.

researchmap

開催年月日： 2018年

researchmap

開催年月日： 2018年

researchmap

開催年月日： 2018年

記述言語：日本語  

researchmap

開催年月日： 2018年

記述言語：日本語  

researchmap

開催年月日： 2018年

記述言語：日本語  

researchmap

開催年月日： 2018年

記述言語：日本語  

researchmap

開催年月日： 2018年

記述言語：英語  

While standard laser range finders use modulation signals, such as sharp pulses, the method we devised employs laser diode's frequency noise, and a frequency discriminator, to produce the intensity noise signal, which we use to generate fast physical random numbers. Observed through a frequency discriminator, beams traveling along two different paths share intensity noise patterns, i.e., the same fast physical random numbers, but with a time lag. We compared the two, and calculated their cross-correlation. By sweeping their time lags, we confirmed the length of the two optical paths, up to 50m.

researchmap

開催年月日： 2018年

記述言語：英語  

An inordinate amount of time, effort (and paper) has been spent trying to find a way to stabilize laser-diode frequencies, but our research team has been working on the premise, that frequency instability can, in fact, have its up-sides. In the present work, we focus on a method that uses laser diodes' own noise to generate physical random numbers. Introducing a frequency discriminator as a reference, we control and stabilize the difference between the frequency reference and the laser frequency, thereby generating random numbers at a suitable point.

researchmap

開催年月日： 2017年3月

記述言語：日本語  

researchmap

開催年月日： 2017年3月

記述言語：日本語  

researchmap

開催年月日： 2017年3月

記述言語：日本語  

researchmap

開催年月日： 2017年

記述言語：日本語  

researchmap

開催年月日： 2017年

記述言語：日本語  

researchmap

開催年月日： 2017年

記述言語：日本語  

researchmap

開催年月日： 2017年

記述言語：英語  

In 1996, when the Faculty of Engineering of Niigata University, Niigata Japan first set up its international student exchange program with Otto-von-Guericke-University, in Magdeburg, Germany, few students showed an interest in studying abroad. Twenty years later, the students' attitudes have changed. The number of students who express a desire to study abroad and have experienced the international conference has increased markedly. In this article, two directions of opportunities for students to start studying abroad are presented; one is short-term summer school program as a subject of general education to remove the students' barriers to go abroad, and the other is research-oriented students' exchange program.

researchmap

開催年月日： 2016年3月

記述言語：日本語  

researchmap

開催年月日： 2016年3月

記述言語：日本語  

researchmap

開催年月日： 2016年3月

記述言語：日本語  

researchmap

開催年月日： 2016年3月

記述言語：日本語  

researchmap

開催年月日： 2016年3月

記述言語：日本語  

researchmap

開催年月日： 2016年

記述言語：日本語  

researchmap

開催年月日： 2016年

記述言語：日本語  

researchmap

開催年月日： 2016年

記述言語：日本語  

researchmap

開催年月日： 2016年

記述言語：日本語  

researchmap

開催年月日： 2016年

記述言語：日本語  

researchmap

開催年月日： 2015年9月

記述言語：日本語  

researchmap

開催年月日： 2015年9月

記述言語：日本語  

researchmap

開催年月日： 2015年9月

記述言語：日本語  

researchmap

開催年月日： 2015年1月

記述言語：日本語  

researchmap

開催年月日： 2015年

記述言語：日本語  

researchmap

開催年月日： 2015年

researchmap

開催年月日： 2015年

記述言語：日本語  

researchmap

開催年月日： 2015年

記述言語：英語  

Semiconductor laser range-finder systems use so-called "time-of-flight" methods that require us to modulate semiconductor lasers' intensity and frequency, and detect those of reflected lights, in order to compare optical paths to the reference and the target. But, accurate measurement requires both high-speed modulation and detection systems. By taking advantage of semiconductor lasers' broad-spectrum frequency noise, which has a range of up to a few GHz, and converting it to intensity noise, we were able to generate a set of high-speed physical random numbers that we used to precisely measure the distance. We tuned the semiconductor lasers' oscillation frequencies loosely to the Rb absorption line and converted their frequency noise to intensity noise, in the light transmitted. Observed through a frequency discriminator, beams traveling along two different paths will always share intensity noise patterns, but there is a time lag. We calculate the cross-correlation of the two signals by sweeping their time lags. The one with the highest degree of correlation was that corresponding to the difference in the length of the two optical paths. Through our experiments, we confirmed that the system was accurate up to a distance of 50 m, at a resolution of 0.03 m, when the sampling rate was adjusted to 0.2 ns.

researchmap

開催年月日： 2014年8月

記述言語：日本語  

半導体レーザは,低コスト,軽量,低電力,長寿命などの利点から,光距離計測の光源として用いられている.また,半導体レーザは,その発振周波数が変動する周波数雑音を持っており,私たちはそれを用いて物理乱数生成を行ってきた.本研究では,この生成された物理乱数を用いた新しい光距離計測法を考案し計測を行ったので報告する.通常の光距離計測は,パルスなどの変調信号を用いているが,本方式では変調信号の代わりに周波数雑音を用いた.周波数変動は,Rb-D_2吸収線を用いて透過光強度に変換し,距離測定を行った.これにより変調を加えず,0.06mの分解能で,50mまでの距離計測を行うことができた.また,サンプリングレートを変えずに分解能の向上を図る検討を行ったためここに報告する.

researchmap

開催年月日： 2014年8月

記述言語：日本語  

インターネット社会において、暗号技術は必要不可欠なものとなっている。現在多く使われている疑似乱数を用いた暗号は、解読に膨大な時間がかかることを担保に安全性を保っている。しかし、高速処理可能なコンピュータの登場により、解読される危険性がでてきた。一方で、理論上解読不可能な量子暗号通信の研究が進んでおり、物理乱数が大量に必要とされている。本研究では、半導体レーザの周波数雑音を用いて物理乱数の生成を行った。今回は、面発光型レーザ(VCSEL)とファブリ・ペロー型レーザ(FPLD)を用いて乱数生成を行い、VCSELでは120Gb/s、ではFPLDでは40Gb/sで乱数生成できた。

researchmap

開催年月日： 2014年8月

記述言語：日本語  

半導体レーザは,低コスト,軽量,低電力,長寿命などの利点から,光距離計測の光源として用いられている.また,半導体レーザは,その発振周波数が変動する周波数雑音を持っており,私たちはそれを用いて物理乱数生成を行ってきた.本研究では,この生成された物理乱数を用いた新しい光距離計測法を考案し計測を行ったので報告する.通常の光距離計測は,パルスなどの変調信号を用いているが,本方式では変調信号の代わりに周波数雑音を用いた.周波数変動は,Rb-D_2吸収線を用いて透過光強度に変換し,距離測定を行った.これにより変調を加えず,0.06mの分解能で,50mまでの距離計測を行うことができた.また,サンプリングレートを変えずに分解能の向上を図る検討を行ったためここに報告する.

researchmap

開催年月日： 2014年3月

記述言語：日本語  

researchmap

開催年月日： 2014年3月

記述言語：日本語  

researchmap

開催年月日： 2014年3月

記述言語：日本語  

researchmap

開催年月日： 2014年3月

記述言語：日本語  

researchmap

開催年月日： 2014年3月

記述言語：日本語  

researchmap

開催年月日： 2014年3月

記述言語：日本語  

researchmap

開催年月日： 2014年3月

記述言語：日本語  

researchmap

開催年月日： 2014年

記述言語：日本語  

researchmap

開催年月日： 2014年

記述言語：日本語  

researchmap

開催年月日： 2014年

記述言語：日本語  

researchmap

開催年月日： 2014年

記述言語：日本語  

researchmap

開催年月日： 2014年

記述言語：日本語  

researchmap

開催年月日： 2014年

researchmap

開催年月日： 2014年

記述言語：日本語  

researchmap

開催年月日： 2014年

記述言語：日本語  

researchmap

開催年月日： 2013年8月

記述言語：日本語  

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザから出力された光は強度及び周波数が変動する高速の雑音特性を持っている。本研究ではその周波数雑音を、周波数弁別器を利用して光強度に変換し、その信号から物理乱数の高速生成を行っている。今回の研究では半導体レーザの発振幅を外部共振器を利用して狭窄化し、そのときの物理乱数とフリーランニング時の物理乱数の比較を行った。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザは,自然放出光の影響による振幅揺らぎとキャリア密度の変動から,屈折率の変動,すなわち発振周波数の変動となる周波数揺らぎを保有している.本研究では,半導体レーザの周波数雑音特性を積極的に利用した新たな応用として,光距離計測が可能か検討した.我々が提案する光距離計測では,周波数雑音の比較により、距離差を求める.それにより,光源の変調を必要とせず,遠距離でも測定精度が変わらないレーザ距離計測が可能と考えられる.ここでは,提案手法により0〜35 mの光距離計測検討を行ったので報告する.

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザから出力された光は強度及び周波数が変動する高速の雑音特性を持っている。本研究ではその周波数雑音を、周波数弁別器を利用して光強度に変換し、その信号から物理乱数の高速生成を行っている。今回の研究では半導体レーザの発振幅を外部共振器を利用して狭窄化し、そのときの物理乱数とフリーランニング時の物理乱数の比較を行った。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

近年の高度情報化社会の発展に伴い、インターネットなどを通じ情報を交換する機会が増加し、情報の保護という観点から情報の暗号化が日々重要視されている。そこで、解読が困難である「物理乱数」が注目を集めているが、高速に生成することは困難であるとされている。本研究では、「物理乱数」を高速に生成する方法として、半導体レーザが持つ、出力光の周波数が広帯域にかつ不規則に変化する物理現象である「周波数雑音特性」を利用する。Rbの吸収線を利用しレーザ光の周波数の変化を、光強度の変化に変換することで検出し、それをデジタル数値化することで「物理乱数」を高速に生成している。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザは,自然放出光の影響による振幅揺らぎとキャリア密度の変動から,屈折率の変動,すなわち発振周波数の変動となる周波数揺らぎを保有している.本研究では,半導体レーザの周波数雑音特性を積極的に利用した新たな応用として,光距離計測が可能か検討した.我々が提案する光距離計測では,周波数雑音の比較により、距離差を求める.それにより,光源の変調を必要とせず,遠距離でも測定精度が変わらないレーザ距離計測が可能と考えられる.ここでは,提案手法により0〜35 mの光距離計測検討を行ったので報告する.

researchmap

開催年月日： 2013年8月

記述言語：日本語  

近年の高度情報化社会の発展に伴い、インターネットなどを通じ情報を交換する機会が増加し、情報の保護という観点から情報の暗号化が日々重要視されている。そこで、解読が困難である「物理乱数」が注目を集めているが、高速に生成することは困難であるとされている。本研究では、「物理乱数」を高速に生成する方法として、半導体レーザが持つ、出力光の周波数が広帯域にかつ不規則に変化する物理現象である「周波数雑音特性」を利用する。Rbの吸収線を利用しレーザ光の周波数の変化を、光強度の変化に変換することで検出し、それをデジタル数値化することで「物理乱数」を高速に生成している。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザは,自然放出光の影響による振幅揺らぎとキャリア密度の変動から,屈折率の変動,すなわち発振周波数の変動となる周波数揺らぎを保有している.本研究では,半導体レーザの周波数雑音特性を積極的に利用した新たな応用として,光距離計測が可能か検討した.我々が提案する光距離計測では,周波数雑音の比較により、距離差を求める.それにより,光源の変調を必要とせず,遠距離でも測定精度が変わらないレーザ距離計測が可能と考えられる.ここでは,提案手法により0〜35 mの光距離計測検討を行ったので報告する.

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザから出力された光は強度及び周波数が変動する高速の雑音特性を持っている。本研究ではその周波数雑音を、周波数弁別器を利用して光強度に変換し、その信号から物理乱数の高速生成を行っている。今回の研究では半導体レーザの発振幅を外部共振器を利用して狭窄化し、そのときの物理乱数とフリーランニング時の物理乱数の比較を行った。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザから出力された光は強度及び周波数が変動する高速の雑音特性を持っている。本研究ではその周波数雑音を、周波数弁別器を利用して光強度に変換し、その信号から物理乱数の高速生成を行っている。今回の研究では半導体レーザの発振幅を外部共振器を利用して狭窄化し、そのときの物理乱数とフリーランニング時の物理乱数の比較を行った。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

近年の高度情報化社会の発展に伴い、インターネットなどを通じ情報を交換する機会が増加し、情報の保護という観点から情報の暗号化が日々重要視されている。そこで、解読が困難である「物理乱数」が注目を集めているが、高速に生成することは困難であるとされている。本研究では、「物理乱数」を高速に生成する方法として、半導体レーザが持つ、出力光の周波数が広帯域にかつ不規則に変化する物理現象である「周波数雑音特性」を利用する。Rbの吸収線を利用しレーザ光の周波数の変化を、光強度の変化に変換することで検出し、それをデジタル数値化することで「物理乱数」を高速に生成している。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザは,自然放出光の影響による振幅揺らぎとキャリア密度の変動から,屈折率の変動,すなわち発振周波数の変動となる周波数揺らぎを保有している.本研究では,半導体レーザの周波数雑音特性を積極的に利用した新たな応用として,光距離計測が可能か検討した.我々が提案する光距離計測では,周波数雑音の比較により、距離差を求める.それにより,光源の変調を必要とせず,遠距離でも測定精度が変わらないレーザ距離計測が可能と考えられる.ここでは,提案手法により0〜35 mの光距離計測検討を行ったので報告する.

researchmap

開催年月日： 2013年8月

記述言語：日本語  

近年の高度情報化社会の発展に伴い、インターネットなどを通じ情報を交換する機会が増加し、情報の保護という観点から情報の暗号化が日々重要視されている。そこで、解読が困難である「物理乱数」が注目を集めているが、高速に生成することは困難であるとされている。本研究では、「物理乱数」を高速に生成する方法として、半導体レーザが持つ、出力光の周波数が広帯域にかつ不規則に変化する物理現象である「周波数雑音特性」を利用する。Rbの吸収線を利用しレーザ光の周波数の変化を、光強度の変化に変換することで検出し、それをデジタル数値化することで「物理乱数」を高速に生成している。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザは,自然放出光の影響による振幅揺らぎとキャリア密度の変動から,屈折率の変動,すなわち発振周波数の変動となる周波数揺らぎを保有している.本研究では,半導体レーザの周波数雑音特性を積極的に利用した新たな応用として,光距離計測が可能か検討した.我々が提案する光距離計測では,周波数雑音の比較により、距離差を求める.それにより,光源の変調を必要とせず,遠距離でも測定精度が変わらないレーザ距離計測が可能と考えられる.ここでは,提案手法により0〜35 mの光距離計測検討を行ったので報告する.

researchmap

開催年月日： 2013年8月

記述言語：日本語  

半導体レーザから出力された光は強度及び周波数が変動する高速の雑音特性を持っている。本研究ではその周波数雑音を、周波数弁別器を利用して光強度に変換し、その信号から物理乱数の高速生成を行っている。今回の研究では半導体レーザの発振幅を外部共振器を利用して狭窄化し、そのときの物理乱数とフリーランニング時の物理乱数の比較を行った。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

近年の高度情報化社会の発展に伴い、インターネットなどを通じ情報を交換する機会が増加し、情報の保護という観点から情報の暗号化が日々重要視されている。そこで、解読が困難である「物理乱数」が注目を集めているが、高速に生成することは困難であるとされている。本研究では、「物理乱数」を高速に生成する方法として、半導体レーザが持つ、出力光の周波数が広帯域にかつ不規則に変化する物理現象である「周波数雑音特性」を利用する。Rbの吸収線を利用しレーザ光の周波数の変化を、光強度の変化に変換することで検出し、それをデジタル数値化することで「物理乱数」を高速に生成している。

researchmap

開催年月日： 2013年8月

記述言語：日本語  

researchmap

開催年月日： 2013年8月

記述言語：日本語  

researchmap

開催年月日： 2013年8月

記述言語：日本語  

researchmap

開催年月日： 2013年5月

記述言語：日本語  

半導体レーザは、自然放出光の影響により、活性層内のキャリア密度の変動がおき、屈折率が変化し、発振周波数が変動する周波数雑音を内在している。我々は、この非周期的で高速な周波数雑音を積極的に用い、物理乱数生成システムを構築してきた。周波数雑音による半導体レーザの発振周波数変動幅は、主に発振幅として表現される。本研究では、フリーランニング半導体レーザと線幅の細い外部共振器半導体レーザを用いて、それぞれ乱数を生成した。生成した各乱数列を暗号用乱数検定FIPS140-2に通し、評価結果を比較し、乱数を生成する半導体レーザの発振幅が乱数性に及ぼす影響を考察した。

researchmap

開催年月日： 2013年5月

記述言語：日本語  

researchmap

開催年月日： 2013年3月

記述言語：日本語  

researchmap

開催年月日： 2013年3月

記述言語：日本語  

researchmap

開催年月日： 2013年3月

記述言語：日本語  

researchmap

開催年月日： 2013年

researchmap

開催年月日： 2013年

researchmap

開催年月日： 2013年

記述言語：日本語  

researchmap

開催年月日： 2013年

記述言語：日本語  

researchmap

開催年月日： 2013年

記述言語：英語  

The Japanese Student Services Organization (JASSO) has started its "Short-Stay and Short-Visit scholarship programs (SS-SV programs)" in the academic year 2011. The Faculty of Engineering, Niigata University, has obtained these scholarships for both German and Japanese students in 2011 and 2012. The objective of these "SS-SV programs" is to support students to visit a foreign country and stay there for less than three months. Because of our past experience of the "Two-week Summer School", which has been developed within the cooperation between Otto-von-Guericke-University Magdeburg, Germany and Niigata University, Japan since 1996, we experienced that a short term stay in a foreign country works as an initiator for the students' interest and will to study further in foreign countries. The authors believe that this type of short-term exchanges has actually proved to be very effective to encourage the students in engineering fields to start international activities.

researchmap

開催年月日： 2013年

researchmap

開催年月日： 2013年

researchmap

開催年月日： 2013年

記述言語：日本語  

researchmap

開催年月日： 2013年

記述言語：日本語  

researchmap

開催年月日： 2012年12月

記述言語：日本語  

researchmap

開催年月日： 2012年12月

記述言語：日本語  

researchmap

開催年月日： 2012年8月

記述言語：日本語  

researchmap

開催年月日： 2012年8月

記述言語：日本語  

大規模シミュレーションや通信の暗号化を行う際に現行では一般的に擬似乱数が用いられている.しかし,近年物理乱数への期待が非常に高まっており,半導体レーザカオスを利用した物理乱数の高速生成も報告されている.そこで本研究では,面発光型半導体レーザの周波数雑音を,Rb原子の吸収線を介して光強度雑音に変換し,A/Dコンバータで2進数列にすることで乱数を生成させ,より高速な物理乱数生成の可能性を検討した.

researchmap

開催年月日： 2012年8月

記述言語：日本語  

大規模シミュレーションや通信の暗号化を行う際に現行では一般的に擬似乱数が用いられている.しかし,近年物理乱数への期待が非常に高まっており,半導体レーザカオスを利用した物理乱数の高速生成も報告されている.そこで本研究では,面発光型半導体レーザの周波数雑音を,Rb原子の吸収線を介して光強度雑音に変換し,A/Dコンバータで2進数列にすることで乱数を生成させ,より高速な物理乱数生成の可能性を検討した.

researchmap

開催年月日： 2012年8月

記述言語：日本語  

半導体レーザは、キャリア密度の変動で利得や屈折率が変動し、単一縦モード発振中でも周波数雑音が発生する。我々はこの半導体レーザの周波数雑音を、周波数弁別器を用いて光強度雑音に変換し、更にA/Dで2進数にすることで、物理乱数の生成を行ってきた。しかし、半導体レーザの発振周波数が大きく変動すると、生成される乱数の乱数性が劣化する可能性がある。そのため、安定化半導体レーザによる物理乱数の乱数検定通過率を測定した。

researchmap

開催年月日： 2012年8月

記述言語：日本語  

researchmap

開催年月日： 2012年8月

記述言語：日本語  

半導体レーザは、キャリア密度の変動で利得や屈折率が変動し、単一縦モード発振中でも周波数雑音が発生する。我々はこの半導体レーザの周波数雑音を、周波数弁別器を用いて光強度雑音に変換し、更にA/Dで2進数にすることで、物理乱数の生成を行ってきた。しかし、半導体レーザの発振周波数が大きく変動すると、生成される乱数の乱数性が劣化する可能性がある。そのため、安定化半導体レーザによる物理乱数の乱数検定通過率を測定した。

researchmap

開催年月日： 2012年8月

記述言語：日本語  

大規模シミュレーションや通信の暗号化を行う際に現行では一般的に擬似乱数が用いられている.しかし,近年物理乱数への期待が非常に高まっており,半導体レーザカオスを利用した物理乱数の高速生成も報告されている.そこで本研究では,面発光型半導体レーザの周波数雑音を,Rb原子の吸収線を介して光強度雑音に変換し,A/Dコンバータで2進数列にすることで乱数を生成させ,より高速な物理乱数生成の可能性を検討した.

researchmap

開催年月日： 2012年8月

記述言語：日本語  

半導体レーザは、キャリア密度の変動で利得や屈折率が変動し、単一縦モード発振中でも周波数雑音が発生する。我々はこの半導体レーザの周波数雑音を、周波数弁別器を用いて光強度雑音に変換し、更にA/Dで2進数にすることで、物理乱数の生成を行ってきた。しかし、半導体レーザの発振周波数が大きく変動すると、生成される乱数の乱数性が劣化する可能性がある。そのため、安定化半導体レーザによる物理乱数の乱数検定通過率を測定した。

researchmap

開催年月日： 2012年8月

記述言語：日本語  

大規模シミュレーションや通信の暗号化を行う際に現行では一般的に擬似乱数が用いられている.しかし,近年物理乱数への期待が非常に高まっており,半導体レーザカオスを利用した物理乱数の高速生成も報告されている.そこで本研究では,面発光型半導体レーザの周波数雑音を,Rb原子の吸収線を介して光強度雑音に変換し,A/Dコンバータで2進数列にすることで乱数を生成させ,より高速な物理乱数生成の可能性を検討した.

researchmap

開催年月日： 2012年8月

記述言語：日本語  

半導体レーザは、キャリア密度の変動で利得や屈折率が変動し、単一縦モード発振中でも周波数雑音が発生する。我々はこの半導体レーザの周波数雑音を、周波数弁別器を用いて光強度雑音に変換し、更にA/Dで2進数にすることで、物理乱数の生成を行ってきた。しかし、半導体レーザの発振周波数が大きく変動すると、生成される乱数の乱数性が劣化する可能性がある。そのため、安定化半導体レーザによる物理乱数の乱数検定通過率を測定した。

researchmap

開催年月日： 2012年8月

記述言語：日本語  

大規模シミュレーションや通信の暗号化を行う際に現行では一般的に擬似乱数が用いられている.しかし,近年物理乱数への期待が非常に高まっており,半導体レーザカオスを利用した物理乱数の高速生成も報告されている.そこで本研究では,面発光型半導体レーザの周波数雑音を,Rb原子の吸収線を介して光強度雑音に変換し,A/Dコンバータで2進数列にすることで乱数を生成させ,より高速な物理乱数生成の可能性を検討した.

researchmap

開催年月日： 2012年8月

記述言語：日本語  

半導体レーザは、キャリア密度の変動で利得や屈折率が変動し、単一縦モード発振中でも周波数雑音が発生する。我々はこの半導体レーザの周波数雑音を、周波数弁別器を用いて光強度雑音に変換し、更にA/Dで2進数にすることで、物理乱数の生成を行ってきた。しかし、半導体レーザの発振周波数が大きく変動すると、生成される乱数の乱数性が劣化する可能性がある。そのため、安定化半導体レーザによる物理乱数の乱数検定通過率を測定した。

researchmap

開催年月日： 2012年8月

記述言語：日本語  

大規模シミュレーションや通信の暗号化を行う際に現行では一般的に擬似乱数が用いられている.しかし,近年物理乱数への期待が非常に高まっており,半導体レーザカオスを利用した物理乱数の高速生成も報告されている.そこで本研究では,面発光型半導体レーザの周波数雑音を,Rb原子の吸収線を介して光強度雑音に変換し,A/Dコンバータで2進数列にすることで乱数を生成させ,より高速な物理乱数生成の可能性を検討した.

researchmap

開催年月日： 2012年3月

記述言語：日本語  

researchmap

開催年月日： 2012年3月

記述言語：日本語  

researchmap

開催年月日： 2012年3月

記述言語：日本語  

researchmap

開催年月日： 2012年3月

記述言語：日本語  

researchmap

開催年月日： 2012年3月

記述言語：日本語  

researchmap

開催年月日： 2012年3月

記述言語：日本語  

researchmap

開催年月日： 2012年3月

記述言語：日本語  

researchmap

開催年月日： 2012年

researchmap

開催年月日： 2012年

記述言語：日本語  

researchmap

開催年月日： 2012年

記述言語：日本語  

researchmap

開催年月日： 2012年

記述言語：日本語  

researchmap

開催年月日： 2012年

記述言語：日本語  

researchmap

開催年月日： 2012年

記述言語：日本語  

researchmap

開催年月日： 2012年

researchmap

開催年月日： 2012年

researchmap

開催年月日： 2011年3月

記述言語：日本語  

researchmap

開催年月日： 2011年3月

記述言語：日本語  

researchmap

開催年月日： 2011年1月

記述言語：日本語  

researchmap

開催年月日： 2011年

記述言語：日本語  

researchmap

開催年月日： 2011年

researchmap

開催年月日： 2010年10月

記述言語：英語  

researchmap

開催年月日： 2010年10月

記述言語：英語  

researchmap

開催年月日： 2010年3月

記述言語：日本語  

researchmap

開催年月日： 2010年3月

記述言語：日本語  

researchmap

開催年月日： 2010年3月

記述言語：日本語  

researchmap

開催年月日： 2010年3月

記述言語：日本語  

researchmap

開催年月日： 2010年3月

記述言語：日本語  

researchmap

開催年月日： 2010年3月

記述言語：日本語  

researchmap

開催年月日： 2010年2月

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

researchmap

開催年月日： 2010年

記述言語：日本語  

The purpose of this study is about noise reduction by Active Noise Control (ANC) at the opening with a louver which attached Piezoelectric Card Speaker. In a house and an apartment not only machinery, louvers are used at large opening aimed for air conditioning and ventilation. Leakage of a sound from the opening set louver becomes a problem. In this experimental study, proposed ANC system is independent parallel control system using two single channel ANC systems. One of them, secondary noise source is set at each bane down side of louver. The other one is set slit of enclosure opening. The experimental results show that noise reduction is obtained from 5dB to 25dB in sound field on this proposed ANC system.

researchmap

開催年月日： 2009年10月

記述言語：英語  

researchmap

開催年月日： 2009年8月

記述言語：日本語  

researchmap

開催年月日： 2009年8月

記述言語：日本語  

researchmap

開催年月日： 2009年8月

記述言語：日本語  

researchmap

開催年月日： 2009年3月

記述言語：日本語  

researchmap

開催年月日： 2009年3月

記述言語：日本語  

researchmap

開催年月日： 2009年3月

記述言語：日本語  

researchmap

開催年月日： 2009年3月

記述言語：日本語  

researchmap

開催年月日： 2009年3月

記述言語：日本語  

researchmap

開催年月日： 2009年

記述言語：日本語  

researchmap

開催年月日： 2009年

記述言語：日本語  

researchmap

開催年月日： 2009年

記述言語：日本語  

researchmap

開催年月日： 2009年

記述言語：日本語  

Sirocco fan having a big static pressure is used for ventilation of the bathroom or cooling of the projector. This paper described the reduction of an air born sound radiated from the sirocco fan when put an absorption sheet on the casing inside. And an airflow-static pressure characteristics and noise reduction was clarified when change the kind and the thickness of absorption sheet. An air born sound was reduced to occur by putting absorption sheet on the casing inside, but it became clear that maximum airflow decreased with it.

researchmap

開催年月日： 2009年

記述言語：日本語  

researchmap

開催年月日： 2009年

記述言語：日本語  

researchmap

開催年月日： 2009年

記述言語：日本語  

researchmap

開催年月日： 2009年

記述言語：日本語  

researchmap

開催年月日： 2009年

記述言語：日本語  

researchmap

開催年月日： 2008年9月

記述言語：日本語  

researchmap

開催年月日： 2008年9月

記述言語：日本語  

researchmap

開催年月日： 2008年5月

記述言語：英語  

researchmap

開催年月日： 2008年

記述言語：日本語  

researchmap

開催年月日： 2008年

記述言語：日本語  

researchmap

開催年月日： 2008年

記述言語：日本語  

researchmap

開催年月日： 2008年

記述言語：日本語  

researchmap

開催年月日： 2008年

記述言語：日本語  

researchmap

開催年月日： 2007年3月

記述言語：日本語  

researchmap

開催年月日： 2007年

記述言語：日本語  

researchmap

開催年月日： 2007年

researchmap

開催年月日： 2007年

記述言語：日本語  

researchmap

開催年月日： 2006年12月

記述言語：英語  

researchmap

開催年月日： 2006年12月

記述言語：英語  

researchmap

開催年月日： 2006年3月

記述言語：日本語  

researchmap

開催年月日： 2006年3月

記述言語：日本語  

researchmap

開催年月日： 2006年3月

記述言語：日本語  

researchmap

開催年月日： 2006年3月

記述言語：日本語  

researchmap

開催年月日： 2006年

記述言語：日本語  

researchmap

開催年月日： 2006年

記述言語：日本語  

researchmap

開催年月日： 2006年

記述言語：日本語  

researchmap

開催年月日： 2006年

記述言語：日本語  

researchmap

開催年月日： 2006年

記述言語：日本語  

researchmap

開催年月日： 2006年

記述言語：日本語  

The purpose of this study is about noise reduction by Active Noise Control at the opening with a louver which installed Piezoelectric Vibrator. From the viewpoint of improvement of appearance and privacy, louvers are used at large opening aimed for air conditioning and ventilation. In late years, in a house and an apartment, a leak of a sound from the opening which installed a louver becomes a problem. The experimental results show that noise reduction is obtained from 5dB to 30dB at control point by ANC system.

researchmap

開催年月日： 2005年3月

記述言語：日本語  

researchmap

開催年月日： 2005年

記述言語：日本語  

researchmap

開催年月日： 2005年

記述言語：日本語  

This paper describes an acoustic diagnosis for a failure aerodynamic sound in a micro DC fan motor assembly line. The failure sound is caused by assembly accuracy of which an eccentricity of fan casing, a yawing of fan blade, etc. Proposed acoustic diagnosis technique is used to Adaptive Line Enhancer (ALE) to extract a periodic abnormal signal including aerodynamic noise generated by rotating a micro DC fan motor. Then, this research performed improvement in a S/N ratio in sound diagnosis of a micro DC fan using adaptive line enhancer. Consequently, the noise signal is not correlative in time decreased by about 10dB, the typical periodic signal with high correlation was acquired as an output signal, and it was cleared that this periodic signal could be used for unusual diagnosis.

researchmap

開催年月日： 2005年

記述言語：日本語  

researchmap

開催年月日： 2003年9月

記述言語：日本語  

The attenuation characteristics of a slit resonator that has the adaptive feedback ANC system for leakage noise at a ventilation aperture of the package is investigated. The discrete tones that are radiate from an AC axial fan are controlled by DSP using Filtered-X LMS algorithm. The attenuation level at each discrete tone in using the circular slit resonator is between 4dB and 14dB. Also, the attenuation level between 6dB and 15dB is observed in the ellipse slit resonator. The proposed system, which consists of a slit resonator with control speakers and the adaptive feedback ANC, enable us to reduce discrete tones effectively.

researchmap

開催年月日： 2003年6月

記述言語：日本語  

This paper deals with the development of a new method for Measurement of powder level in the cylinder. For monitoring of automated filling processes of cartridges in a series production a new measurement method was developed which allows to detect rapidly incorrect products and to improve the process capability by the use of this method. The aim of this research work is to measure the level of powder in a cartridge without contacting the powder. The powder is a mixture of solid particles and air, and therefore porous media from the viewpoint of acoustics. As above, the inside of the cartridge, which is filled with powder, is an acoustic system including porous media. The here developed measuring method use the relationship between amount of powder in the cartridge and the characteristics of the transfer function of the acoustic system. The acoustic characteristic of the powder, which is used for the theoretical analysis and FEM was also measured.

researchmap

開催年月日： 2003年6月

記述言語：日本語  

This paper describes noise attenuation characteristics of a slit resonator that has adaptive feedback NANC system for silencing leakage noise at ventilation aperature. The slit resonator contains a thin air layer that extends radially over a very short axial length. In order to calculate the noise attenuation, computer simulations use the actual data such as fan noise and the transfer function from the canceling source to the error microphone. The effectiveness of the slit resonator that has adaptive feedback ANC system is clarified by computer simulations.

researchmap

開催年月日： 2003年4月

記述言語：英語  

researchmap

開催年月日： 2003年4月

記述言語：英語  

researchmap

開催年月日： 2003年4月

記述言語：英語  

researchmap

開催年月日： 2003年

記述言語：日本語  

The attenuation characteristics of a slit resonator that has the adaptive feedback ANC system for leakage noise at a ventilation aperture of the package is investigated. The discrete tones that are radiate from an AC axial fan are controlled by DSP using Filtered-X LMS algorithm. The attenuation level at each discrete tone in using the circular slit resonator is between 4dB and 14dB. Also, the attenuation level between 6dB and 15dB is observed in the ellipse slit resonator. The proposed system, which consists of a slit resonator with control speakers and the adaptive feedback ANC, enable us to reduce discrete tones effectively.

researchmap

開催年月日： 2003年

researchmap

開催年月日： 2003年

記述言語：日本語  

researchmap

開催年月日： 2003年

記述言語：日本語  

This paper deals with the development of a new method for Measurement of powder level in the cylinder. For monitoring of automated filling processes of cartridges in a series production a new measurement method was developed which allows to detect rapidly incorrect products and to improve the process capability by the use of this method. The aim of this research work is to measure the level of powder in a cartridge without contacting the powder. The powder is a mixture of solid particles and air, and therefore porous media from the viewpoint of acoustics. As above, the inside of the cartridge, which is filled with powder, is an acoustic system including porous media. The here developed measuring method use the relationship between amount of powder in the cartridge and the characteristics of the transfer function of the acoustic system. The acoustic characteristic of the powder, which is used for the theoretical analysis and FEM was also measured.

researchmap

開催年月日： 2003年

記述言語：日本語