Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49354
K. Misu, T. Nagatsuka, S. Wadaka
An m-derived ladder for combining SAW (surface acoustic wave) filters in a contiguous filter bank is proposed. The series element in each m-derived ladder section is composed of a parallel resonant circuit. The input transducer of a SAW filter is used as the shunt element in each section. A pole of attenuation is produced at the resonant frequency of the series element. Thus, the third-harmonic spurious response of the SAW filter is greatly suppressed by setting the pole of attenuation in the vicinity of the third harmonic. A ten-channel version of the filter bank was constructed, operating in the frequency range from 110 to 200 MHz. The insertion loss was 10+or-1.7 dB, which was as low as that of a constant k ladder filter bank, and the attenuation was greater than 42 dB in the third harmonics from 330 to 600 MHz.<>
{"title":"A SAW contiguous filter bank with an m derived ladder","authors":"K. Misu, T. Nagatsuka, S. Wadaka","doi":"10.1109/ULTSYM.1988.49354","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49354","url":null,"abstract":"An m-derived ladder for combining SAW (surface acoustic wave) filters in a contiguous filter bank is proposed. The series element in each m-derived ladder section is composed of a parallel resonant circuit. The input transducer of a SAW filter is used as the shunt element in each section. A pole of attenuation is produced at the resonant frequency of the series element. Thus, the third-harmonic spurious response of the SAW filter is greatly suppressed by setting the pole of attenuation in the vicinity of the third harmonic. A ten-channel version of the filter bank was constructed, operating in the frequency range from 110 to 200 MHz. The insertion loss was 10+or-1.7 dB, which was as low as that of a constant k ladder filter bank, and the attenuation was greater than 42 dB in the third harmonics from 330 to 600 MHz.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115510887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49355
P. Dufilié, J. Hode, J. Desbois
An improved structure for low loss, sharp cutoff, high-rejection filters has been developed. Center frequencies as high as 1500 MHz can be realized with standard optical processing techniques. Relative bandwidths of up to 0.67 K/sup 2/ are achievable. Data are presented for 900-MHz filters on 128 degrees YX-LiNbOI/sub 3/ and 950-MHz filters on 36 degrees YX-LiTaO/sub 3/ each having 3% and 1.6% relative bandwidths. 50-dB out-of-band rejection, and <6-dB insertion loss. By simple scaling of the designs to a 0.65- mu m minimum linewidth, a center frequency of 1.4 GHz can be achieved on LiNbO/sub 3/ and 1.5 GHz on LiTaO/sub 3/.<>
{"title":"A low loss high performance filter structure","authors":"P. Dufilié, J. Hode, J. Desbois","doi":"10.1109/ULTSYM.1988.49355","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49355","url":null,"abstract":"An improved structure for low loss, sharp cutoff, high-rejection filters has been developed. Center frequencies as high as 1500 MHz can be realized with standard optical processing techniques. Relative bandwidths of up to 0.67 K/sup 2/ are achievable. Data are presented for 900-MHz filters on 128 degrees YX-LiNbOI/sub 3/ and 950-MHz filters on 36 degrees YX-LiTaO/sub 3/ each having 3% and 1.6% relative bandwidths. 50-dB out-of-band rejection, and <6-dB insertion loss. By simple scaling of the designs to a 0.65- mu m minimum linewidth, a center frequency of 1.4 GHz can be achieved on LiNbO/sub 3/ and 1.5 GHz on LiTaO/sub 3/.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123128190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49436
R. Lee, J. Vetelino, P. Clarke, A. Roy, J. Turner
The properties of the acoustic wave in a fluid overlay on a piezoelectric substrate are investigated for two different geometries: bounce mode and waveguide mode. Acoustic wave properties such as velocity and attenuation are obtained as a function of the fluid layer thickness and the physical properties of the fluid layer. It is shown that subtle changes in fluid properties will modify the acoustic waves. One or more of these acoustic wave properties can then be used as the sensing element in a fluid microsensor. Very promising results were obtained in the case of the bounce-mode geometry. Both the velocity and the attenuation of the acoustic mode varied in a predictable fashion as the fluid properties changed. In the case of the waveguide geometry the experimental and theoretical values of the velocity agreed quite well. However, the acoustic wave properties were found to be extremely sensitive to geometric factors such as the parallelism of the two solids.<>
{"title":"Prototype microwave acoustic fluid sensors","authors":"R. Lee, J. Vetelino, P. Clarke, A. Roy, J. Turner","doi":"10.1109/ULTSYM.1988.49436","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49436","url":null,"abstract":"The properties of the acoustic wave in a fluid overlay on a piezoelectric substrate are investigated for two different geometries: bounce mode and waveguide mode. Acoustic wave properties such as velocity and attenuation are obtained as a function of the fluid layer thickness and the physical properties of the fluid layer. It is shown that subtle changes in fluid properties will modify the acoustic waves. One or more of these acoustic wave properties can then be used as the sensing element in a fluid microsensor. Very promising results were obtained in the case of the bounce-mode geometry. Both the velocity and the attenuation of the acoustic mode varied in a predictable fashion as the fluid properties changed. In the case of the waveguide geometry the experimental and theoretical values of the velocity agreed quite well. However, the acoustic wave properties were found to be extremely sensitive to geometric factors such as the parallelism of the two solids.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124435347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49367
Y. Ebata, H. Satoh
The authors review SAW (surface acoustic wave) applications which have a growing market and large future potential in Asia. One of the major markets is television-related products, such as stereo sound or bilingual TV sets, CATV (cable television) convertors, satellite TV tuners, and enhanced-definition TV sets. Another market is telecommunication systems, such as pagers, cordless phones, cellular phones, and home security. The latter market is expected to grow rapidly, because of the recent liberalization of the Japanese radio law. Japanese SAW device developments includes not only design technology but also material improvement. Attention is given to SAW substrates and device functions for these applications.<>
{"title":"Current applications and future trends for SAW in Asia","authors":"Y. Ebata, H. Satoh","doi":"10.1109/ULTSYM.1988.49367","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49367","url":null,"abstract":"The authors review SAW (surface acoustic wave) applications which have a growing market and large future potential in Asia. One of the major markets is television-related products, such as stereo sound or bilingual TV sets, CATV (cable television) convertors, satellite TV tuners, and enhanced-definition TV sets. Another market is telecommunication systems, such as pagers, cordless phones, cellular phones, and home security. The latter market is expected to grow rapidly, because of the recent liberalization of the Japanese radio law. Japanese SAW device developments includes not only design technology but also material improvement. Attention is given to SAW substrates and device functions for these applications.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127121297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49351
O. Andreassan, A. L. Viddal
To reduce frequency band waste, and increase the flexibility in future mobile communication satellites, a SAW (surface acoustic wave) filter bank was designed. The filters can be used either as separate filters, or combined with neighbor filters to form continuous passbands both in amplitude and phase. These are called bandwidth switchable SAW filters (BSSF). The principle involves pure signal vector additions based on symmetries in the common transition band, by controlled amplitude and phase response and equal delay. A SAW filter bank with three filters was manufactured and tested with excellent results.<>
{"title":"Bandwidth switchable SAW filters, BSSF, on quartz","authors":"O. Andreassan, A. L. Viddal","doi":"10.1109/ULTSYM.1988.49351","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49351","url":null,"abstract":"To reduce frequency band waste, and increase the flexibility in future mobile communication satellites, a SAW (surface acoustic wave) filter bank was designed. The filters can be used either as separate filters, or combined with neighbor filters to form continuous passbands both in amplitude and phase. These are called bandwidth switchable SAW filters (BSSF). The principle involves pure signal vector additions based on symmetries in the common transition band, by controlled amplitude and phase response and equal delay. A SAW filter bank with three filters was manufactured and tested with excellent results.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125060622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49485
J. Schmolke, H. Emert
It is shown that pulse Doppler CT (computerized tomography) leads to more complete flow images than conventional flow imaging does; not only forward and reverse flow directions but also transverse directions are registered and imaged using a suitable color code. Pulse Doppler CT is proposed in a real-time two-array made and in a non-real-time but more sensitive scanning mode, which also has higher resolution. The reconstruction procedure is illustrated. Also described is an experimental setup that was applied to basic real-time imaging experiments in the two-array mode with artificial objects in a water tank. It is concluded that the method promises advantageous application in blood vessel architecture imaging and organ perfusion observation.<>
{"title":"Ultrasound pulse Doppler tomography","authors":"J. Schmolke, H. Emert","doi":"10.1109/ULTSYM.1988.49485","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49485","url":null,"abstract":"It is shown that pulse Doppler CT (computerized tomography) leads to more complete flow images than conventional flow imaging does; not only forward and reverse flow directions but also transverse directions are registered and imaged using a suitable color code. Pulse Doppler CT is proposed in a real-time two-array made and in a non-real-time but more sensitive scanning mode, which also has higher resolution. The reconstruction procedure is illustrated. Also described is an experimental setup that was applied to basic real-time imaging experiments in the two-array mode with artificial objects in a water tank. It is concluded that the method promises advantageous application in blood vessel architecture imaging and organ perfusion observation.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125063389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49477
G. Briggs, J. M. Rowe, A. Sinton, D. Spencer
An overview of current methods is provided. Two well-established methods of quantitative analysis are the line-focus-beam system for measuring the velocity and attenuation of leaky surface acoustic waves, and the inversion of the complex-valued V(z) to yield the reflectance function. Now at least three other methods are available. The first involves the use of very short pulses to resolve echoes from different interfaces or from different interactions with the specimen. The Fourier inversion of V(z) has been extended to signals measured through a diode detector, from which the phase information has therefore been lost. A phase retrieval method based on the Gerchberg-Saxton algorithm enables the complex reflectance function to be reconstructed from a modulus only V(z), and the results seem to reproduce the phase change around the Rayleigh angle rather faithfully. Finally, the analysis method used for the line-focus-beam system has been generalized for spherical lenses, and results have been obtained with isotropic materials at frequencies up to 1.5 GHz.<>
{"title":"Quantitative methods in acoustic microscopy","authors":"G. Briggs, J. M. Rowe, A. Sinton, D. Spencer","doi":"10.1109/ULTSYM.1988.49477","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49477","url":null,"abstract":"An overview of current methods is provided. Two well-established methods of quantitative analysis are the line-focus-beam system for measuring the velocity and attenuation of leaky surface acoustic waves, and the inversion of the complex-valued V(z) to yield the reflectance function. Now at least three other methods are available. The first involves the use of very short pulses to resolve echoes from different interfaces or from different interactions with the specimen. The Fourier inversion of V(z) has been extended to signals measured through a diode detector, from which the phase information has therefore been lost. A phase retrieval method based on the Gerchberg-Saxton algorithm enables the complex reflectance function to be reconstructed from a modulus only V(z), and the results seem to reproduce the phase change around the Rayleigh angle rather faithfully. Finally, the analysis method used for the line-focus-beam system has been generalized for spherical lenses, and results have been obtained with isotropic materials at frequencies up to 1.5 GHz.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122495474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49546
K. Sun, M. Xu, B. Sarma, M. Levy
Temperature-dependent ultrasonic attenuation measurements have been performed on a pressed powder sample of YBa/sub 2/Cu/sub 3/O/sub 7/ with frequencies at 10, 27, and 32 MHz. An attenuation anomaly occurs at temperature close to the superconducting transition temperature T/sub c/ (90 K) for each frequency. It is also found that the magnitudes of these attenuation peaks are of quadratic frequency dependence. With normalized attenuation data and by employing the Debye equation for relaxation type ultrasonic attenuation, the relaxation time is found to be exponentially dependent on temperature. Moreover, the velocity of a 10 MHz sound wave propagating in the sample generally increases with decreasing temperature while exhibiting a possible softening around T/sub c/. These variations of attenuation and velocity at temperatures near T/sub c/ may be associated with the structural distortion of YBa/sub 2/Cu/sub 3/O/sub 7/ and may indirectly be a result of superconducting transition.<>
{"title":"Relaxation behavior of ultrasonic attenuation in YBa/sub 2/Cu/sub 3/O/sub 7/","authors":"K. Sun, M. Xu, B. Sarma, M. Levy","doi":"10.1109/ULTSYM.1988.49546","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49546","url":null,"abstract":"Temperature-dependent ultrasonic attenuation measurements have been performed on a pressed powder sample of YBa/sub 2/Cu/sub 3/O/sub 7/ with frequencies at 10, 27, and 32 MHz. An attenuation anomaly occurs at temperature close to the superconducting transition temperature T/sub c/ (90 K) for each frequency. It is also found that the magnitudes of these attenuation peaks are of quadratic frequency dependence. With normalized attenuation data and by employing the Debye equation for relaxation type ultrasonic attenuation, the relaxation time is found to be exponentially dependent on temperature. Moreover, the velocity of a 10 MHz sound wave propagating in the sample generally increases with decreasing temperature while exhibiting a possible softening around T/sub c/. These variations of attenuation and velocity at temperatures near T/sub c/ may be associated with the structural distortion of YBa/sub 2/Cu/sub 3/O/sub 7/ and may indirectly be a result of superconducting transition.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122603081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49500
T. A. Shoup, J. Hart
The authors explain the workings of a modern phase-array imaging system and present examples of the technical advances that have helped make such systems possible. A cardiac imaging system will provide images using transducers from 2.5 to 7.5 MHz, make simultaneous Doppler measurements of blood velocity, including color flow, contain analysis software for making measurements on screen, and support a number of peripherals. Technical advances that have made this possible include the ability to make higher frequency phased-array transducers, new piezoelectric materials, advances in signal processing, and software embedded in the systems. The electronic advances include faster and more dense memories, high-speed but low-power logic, the ability to make gate arrays at reasonable cost, surface-mounted packages and improvements in hard-copy devices and video recording technology.<>
{"title":"Ultrasonic imaging systems","authors":"T. A. Shoup, J. Hart","doi":"10.1109/ULTSYM.1988.49500","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49500","url":null,"abstract":"The authors explain the workings of a modern phase-array imaging system and present examples of the technical advances that have helped make such systems possible. A cardiac imaging system will provide images using transducers from 2.5 to 7.5 MHz, make simultaneous Doppler measurements of blood velocity, including color flow, contain analysis software for making measurements on screen, and support a number of peripherals. Technical advances that have made this possible include the ability to make higher frequency phased-array transducers, new piezoelectric materials, advances in signal processing, and software embedded in the systems. The electronic advances include faster and more dense memories, high-speed but low-power logic, the ability to make gate arrays at reasonable cost, surface-mounted packages and improvements in hard-copy devices and video recording technology.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122654796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1109/ULTSYM.1988.49422
L. Germain, R. Jacques, J. Cheeke
The use of an acoustic microscope as a method for imaging the nonlinearity of thin biological samples is evaluated. Biological tissues are simulated by liquid mixtures of well-known nonlinearity, which are placed at the focal plane between two very thin mylar sheets. The experiment consists of measuring the amplitude of the second harmonic component generated near the focal point as a function of the liquid sample used. A simple theoretical model which assumes that all harmonic generation that takes place within the sample is found to be in good agreement with the experimental results. This shows that the acoustic microscope is sensitive to the nonlinearity of the sample at the focal plane.<>
{"title":"Nonlinear generation of harmonics near the focus of an acoustic lens: application to nonlinear imaging of biological media","authors":"L. Germain, R. Jacques, J. Cheeke","doi":"10.1109/ULTSYM.1988.49422","DOIUrl":"https://doi.org/10.1109/ULTSYM.1988.49422","url":null,"abstract":"The use of an acoustic microscope as a method for imaging the nonlinearity of thin biological samples is evaluated. Biological tissues are simulated by liquid mixtures of well-known nonlinearity, which are placed at the focal plane between two very thin mylar sheets. The experiment consists of measuring the amplitude of the second harmonic component generated near the focal point as a function of the liquid sample used. A simple theoretical model which assumes that all harmonic generation that takes place within the sample is found to be in good agreement with the experimental results. This shows that the acoustic microscope is sensitive to the nonlinearity of the sample at the focal plane.<<ETX>>","PeriodicalId":263198,"journal":{"name":"IEEE 1988 Ultrasonics Symposium Proceedings.","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122886562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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