Pub Date : 2006-06-01DOI: 10.1109/FREQ.2006.275406
Zhijun Chen, Tao Han, W. Shi, X. Ji, Lianger Li
Microacoustic sensors can be employed to measure physical, chemical and biological liquid properties. Among these sensors the potentially most sensitive is the Lamb wave device. The device is influenced by the mechanical and electrical properties of the liquid layer. Additionally, these effects on the device usually couple together. In this paper, considering the measuring of ideal nonviscous liquid, utilizing the partial wave analysis method, we give theoretical derivation and numerical simulation of three-channel Lamb wave devices for separate determination of liquid density and permittivity. Furthermore, using lithium niobate material as an example, according to sensitivity together with excitation efficiency, the optimization of the devices in singly and doubly rotated cuts for separate liquid properties sensing is presented
{"title":"Separate Determination of Liquid Properties with Lamb Wave Devices","authors":"Zhijun Chen, Tao Han, W. Shi, X. Ji, Lianger Li","doi":"10.1109/FREQ.2006.275406","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275406","url":null,"abstract":"Microacoustic sensors can be employed to measure physical, chemical and biological liquid properties. Among these sensors the potentially most sensitive is the Lamb wave device. The device is influenced by the mechanical and electrical properties of the liquid layer. Additionally, these effects on the device usually couple together. In this paper, considering the measuring of ideal nonviscous liquid, utilizing the partial wave analysis method, we give theoretical derivation and numerical simulation of three-channel Lamb wave devices for separate determination of liquid density and permittivity. Furthermore, using lithium niobate material as an example, according to sensitivity together with excitation efficiency, the optimization of the devices in singly and doubly rotated cuts for separate liquid properties sensing is presented","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"110 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115730175","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 : 2006-06-01DOI: 10.1109/FREQ.2006.275393
Hui Zhou, Wei Zhou
A simple length vernier approach has been developed which uses the high stability and high speed of signal transmission and the relation of time and space. It can get high resolution, low cost and simple structure. Based on high stable transmission delay of the signal and the coincidence detection technique, the start and stop signals of a measured short time interval are delayed respectively in the different lines. The line length to transmit the start signal is longer than that of the stop signal according to the measurement resolution, and both of the lines are divided into small subsections according to the measuring precision. Both active and passive device can be used for delay lines, but passive device can get higher resolution and has special problems that need be resolved. Based on the position of the coincidence between two signals, their delay difference can be used to express the measured time interval exactly. With this way, the measurement precision is much better than that of the unit subsection of the two delay lines for start and stop signals. This technique can show much finer than ns resolution and even better in the future. The different delay lines can be used here including coaxial cable, PC board, and even in integrated circuit
{"title":"A Time and Frequency Measurement Technique Based on Length Vernier","authors":"Hui Zhou, Wei Zhou","doi":"10.1109/FREQ.2006.275393","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275393","url":null,"abstract":"A simple length vernier approach has been developed which uses the high stability and high speed of signal transmission and the relation of time and space. It can get high resolution, low cost and simple structure. Based on high stable transmission delay of the signal and the coincidence detection technique, the start and stop signals of a measured short time interval are delayed respectively in the different lines. The line length to transmit the start signal is longer than that of the stop signal according to the measurement resolution, and both of the lines are divided into small subsections according to the measuring precision. Both active and passive device can be used for delay lines, but passive device can get higher resolution and has special problems that need be resolved. Based on the position of the coincidence between two signals, their delay difference can be used to express the measured time interval exactly. With this way, the measurement precision is much better than that of the unit subsection of the two delay lines for start and stop signals. This technique can show much finer than ns resolution and even better in the future. The different delay lines can be used here including coaxial cable, PC board, and even in integrated circuit","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115741312","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 : 2006-06-01DOI: 10.1109/FREQ.2006.275384
Ki-Jae Song, Jaeil Lee, Hyun-Seop Shim
This paper introduces a low in-band phase noise synthesizer with narrow frequency resolution. In order to improve the noise characteristic, the output frequency of the voltage controlled oscillator is converted into a fixed low IF signal by two mixers. Therefore, the N division ratio is relatively reduced, which means the minimization of the in-band phase noise. To confirm the noise performances, this synthesizer is simulated and analyzed through the phase domain noise model. This paper presents the simulation results for the phase noise, spurious, and acquisition time
{"title":"Frequency Synthesizer Using Dual Offset Mixing for Low Phase Noise and Narrow Resolution","authors":"Ki-Jae Song, Jaeil Lee, Hyun-Seop Shim","doi":"10.1109/FREQ.2006.275384","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275384","url":null,"abstract":"This paper introduces a low in-band phase noise synthesizer with narrow frequency resolution. In order to improve the noise characteristic, the output frequency of the voltage controlled oscillator is converted into a fixed low IF signal by two mixers. Therefore, the N division ratio is relatively reduced, which means the minimization of the in-band phase noise. To confirm the noise performances, this synthesizer is simulated and analyzed through the phase domain noise model. This paper presents the simulation results for the phase noise, spurious, and acquisition time","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"97 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123500231","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 : 2006-06-01DOI: 10.1109/FREQ.2006.275362
J. Weber, M. Link, R. Primig, D. Pitzer, M. Schreiter
Film bulk acoustic resonators operating in thickness shear mode at a frequency of 720 MHz are used to characterize liquids with different viscosities. Their advantage over QCM devices are higher packaging density, CMOS-compatibility as well as lower production costs. Sensor response corresponds with theoretical models in the low viscosity regime but deviates strongly for higher viscosities. This behavior is analyzed as well as an assessment of the FBAR as a viscosity sensor is made
{"title":"High Frequency Viscosity Sensing with FBARs","authors":"J. Weber, M. Link, R. Primig, D. Pitzer, M. Schreiter","doi":"10.1109/FREQ.2006.275362","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275362","url":null,"abstract":"Film bulk acoustic resonators operating in thickness shear mode at a frequency of 720 MHz are used to characterize liquids with different viscosities. Their advantage over QCM devices are higher packaging density, CMOS-compatibility as well as lower production costs. Sensor response corresponds with theoretical models in the low viscosity regime but deviates strongly for higher viscosities. This behavior is analyzed as well as an assessment of the FBAR as a viscosity sensor is made","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121923771","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 : 2006-06-01DOI: 10.1109/FREQ.2006.275375
A. Ballato
Simplified derivations of the Quimby compound resonator (QCR) equations are provided, with their reduction to the quartz crystal microbalance (QCM) forms, for both the originally assumed condition of negligible transducer piezocoupling, as well as for the much more interesting case where both the transducer and unknown possess arbitrary piezoelectric coupling factors. For the QCM configuration, the accuracy of the mass determination depends somewhat upon where the frequency measurements are made on the impedance circle. For the QCR situation where both transducer and measurand are piezoelectric, the piezocoupling may be determined along with the elastic coefficients, by alterations in the electrical boundary conditions
{"title":"Compound Resonators and Microweighing Sensors","authors":"A. Ballato","doi":"10.1109/FREQ.2006.275375","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275375","url":null,"abstract":"Simplified derivations of the Quimby compound resonator (QCR) equations are provided, with their reduction to the quartz crystal microbalance (QCM) forms, for both the originally assumed condition of negligible transducer piezocoupling, as well as for the much more interesting case where both the transducer and unknown possess arbitrary piezoelectric coupling factors. For the QCM configuration, the accuracy of the mass determination depends somewhat upon where the frequency measurements are made on the impedance circle. For the QCR situation where both transducer and measurand are piezoelectric, the piezocoupling may be determined along with the elastic coefficients, by alterations in the electrical boundary conditions","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128363311","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 : 2006-06-01DOI: 10.1109/FREQ.2006.275488
D. Howe, J. McGee-Taylor, T. Tassett
A version of Theol variance, called TheoBR variance (BR for "bias-removed" relative to the Allan variance), is constructed. This relative bias correction is applied over a range of the longest recommended Allan r values for a given data run. TheoH deviation ('H' to indicate a hybrid combination of TheoBR, and Allan deviations) is the Allan deviation in short term and switches to the TheoBR, deviation in long term. In the presence of non-integer-power-law and mixed noise types, the approach is as effective and less cumbersome than past approaches, and requires little, if any, a priori knowledge or human judgment of data being analyzed. The substantially gained properties of Theol at large r, to 50 % beyond the longest possible r using the Allan deviation alone, can be obtained without Allan bias. Long-term frequency stability can be obtained in essentially one-third less time. For example, a two-month stability can be obtained with three months of data, rather than the four months of data that are usually required for such a point
{"title":"ThêoH Bias-removal Method","authors":"D. Howe, J. McGee-Taylor, T. Tassett","doi":"10.1109/FREQ.2006.275488","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275488","url":null,"abstract":"A version of Theol variance, called TheoBR variance (BR for \"bias-removed\" relative to the Allan variance), is constructed. This relative bias correction is applied over a range of the longest recommended Allan r values for a given data run. TheoH deviation ('H' to indicate a hybrid combination of TheoBR, and Allan deviations) is the Allan deviation in short term and switches to the TheoBR, deviation in long term. In the presence of non-integer-power-law and mixed noise types, the approach is as effective and less cumbersome than past approaches, and requires little, if any, a priori knowledge or human judgment of data being analyzed. The substantially gained properties of Theol at large r, to 50 % beyond the longest possible r using the Allan deviation alone, can be obtained without Allan bias. Long-term frequency stability can be obtained in essentially one-third less time. For example, a two-month stability can be obtained with three months of data, rather than the four months of data that are usually required for such a point","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128222409","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 : 2006-06-01DOI: 10.1109/FREQ.2006.275415
I. Avramov
This work presents the performance and important design considerations of the first successful highly efficient Rayleigh surface acoustic wave (RSAW) resonator filters using gold (Au) electrode structure. Au metallisation provides corrosion immunity when the devices are operated as polymer coated gas sensors in chemically reactive environments. It is shown that Au, due to its 7 times higher density than Al, provides about 13 times higher frequency sensitivity and a stronger velocity perturbation in resonant devices compared to their RSAW counterparts with aluminium (Al) electrodes. This results in strong excitation of unwanted surface skimming bulk wave (SSBW) modes and transverse wave guide modes (TWGMs) in such resonant Au devices. Practical guidelines for the choice of correct device geometry, Au thickness and spacer variations to maximize coupling to the desired RSAW mode, increase resonator efficiency and loaded Q, as well as minimize interference with parasitic TWGMs are given. Experimental 433 MHz two-port resonators and dual mode inline coupled filters with insertion loss in the -8 to -12 dB range and loaded Q values in the 4500 to 6000 range are presented with emphasis on their polymer coating and gas probing behavior
{"title":"Design of Rayleigh SAW Resonators for Applications as Gas Sensors in Highly Reactive Chemical Environments","authors":"I. Avramov","doi":"10.1109/FREQ.2006.275415","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275415","url":null,"abstract":"This work presents the performance and important design considerations of the first successful highly efficient Rayleigh surface acoustic wave (RSAW) resonator filters using gold (Au) electrode structure. Au metallisation provides corrosion immunity when the devices are operated as polymer coated gas sensors in chemically reactive environments. It is shown that Au, due to its 7 times higher density than Al, provides about 13 times higher frequency sensitivity and a stronger velocity perturbation in resonant devices compared to their RSAW counterparts with aluminium (Al) electrodes. This results in strong excitation of unwanted surface skimming bulk wave (SSBW) modes and transverse wave guide modes (TWGMs) in such resonant Au devices. Practical guidelines for the choice of correct device geometry, Au thickness and spacer variations to maximize coupling to the desired RSAW mode, increase resonator efficiency and loaded Q, as well as minimize interference with parasitic TWGMs are given. Experimental 433 MHz two-port resonators and dual mode inline coupled filters with insertion loss in the -8 to -12 dB range and loaded Q values in the 4500 to 6000 range are presented with emphasis on their polymer coating and gas probing behavior","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127837001","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 : 2006-06-01DOI: 10.1109/FREQ.2006.275402
S. Peil, S. Crane, T. Swanson, C. Ekstrom
We present initial evaluations of our rubidium atomic fountain - the first of six that are designed for continuous operation and for inclusion into the USNO timescale. We have demonstrated short-term performance in weak-gradient, MOT-loaded operation of 1.3 times 10-13/taufrac12. We have made a comparison between our rubidium fountain (NRF1) and cesium fountain (NCF), demonstrating a relative stability characterized by white-frequency noise down to an Allan deviation of 1.5 times 10-15. Assuming that each fountain exhibits the same noise type, the data are consistent with an Allan deviation for our rubidium fountain of 7 times 10-16 at 11 hours. Further upgrades to our cesium fountain should enable more precise comparisons
{"title":"The USNO Rubidium Fountain","authors":"S. Peil, S. Crane, T. Swanson, C. Ekstrom","doi":"10.1109/FREQ.2006.275402","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275402","url":null,"abstract":"We present initial evaluations of our rubidium atomic fountain - the first of six that are designed for continuous operation and for inclusion into the USNO timescale. We have demonstrated short-term performance in weak-gradient, MOT-loaded operation of 1.3 times 10-13/taufrac12. We have made a comparison between our rubidium fountain (NRF1) and cesium fountain (NCF), demonstrating a relative stability characterized by white-frequency noise down to an Allan deviation of 1.5 times 10-15. Assuming that each fountain exhibits the same noise type, the data are consistent with an Allan deviation for our rubidium fountain of 7 times 10-16 at 11 hours. Further upgrades to our cesium fountain should enable more precise comparisons","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129298056","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 : 2006-06-01DOI: 10.1109/FREQ.2006.275448
Yoonkee Kim
In this paper, we report the measured properties of doubly-rotated cuts of bulk-acoustic-wave resonators made of a langasite isomorph material. Test resonators with planoconvex blanks (14 mm diameter, 2 diopter, nominal 10 MHz 5th OT) were fabricated for four different cuts: (thetas = 10deg, phi = 10deg), (thetas = 10deg, phi = 20deg), (thetas = 20deg, phi = 10deg), (thetas = 20deg, phi = 20deg). Using an impedance analyzer, we were able to measure strongly excited fundamental and 3rd overtones of the c- and b-modes, along with their anharmonic modes, as evidenced by their low motional resistances. The a-modes were weakly excited but could also be measured. The theoretical values of eigenmode velocities and piezoelectric coupling coefficients of the doubly-rotated cuts were obtained by solving Christoffel equations. The theoretical values were compared to the measured ones. The frequency-temperature (f-t) characteristics were also measured in the temperature range of -55 degC to 85 degC. The f-t curves of the c- and b-modes showed parabolic characteristics
{"title":"Measurements of Doubly-Rotated-Cuts of Langasite Isomorph","authors":"Yoonkee Kim","doi":"10.1109/FREQ.2006.275448","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275448","url":null,"abstract":"In this paper, we report the measured properties of doubly-rotated cuts of bulk-acoustic-wave resonators made of a langasite isomorph material. Test resonators with planoconvex blanks (14 mm diameter, 2 diopter, nominal 10 MHz 5th OT) were fabricated for four different cuts: (thetas = 10deg, phi = 10deg), (thetas = 10deg, phi = 20deg), (thetas = 20deg, phi = 10deg), (thetas = 20deg, phi = 20deg). Using an impedance analyzer, we were able to measure strongly excited fundamental and 3rd overtones of the c- and b-modes, along with their anharmonic modes, as evidenced by their low motional resistances. The a-modes were weakly excited but could also be measured. The theoretical values of eigenmode velocities and piezoelectric coupling coefficients of the doubly-rotated cuts were obtained by solving Christoffel equations. The theoretical values were compared to the measured ones. The frequency-temperature (f-t) characteristics were also measured in the temperature range of -55 degC to 85 degC. The f-t curves of the c- and b-modes showed parabolic characteristics","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"300 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126742456","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 : 2006-06-01DOI: 10.1109/FREQ.2006.275447
H. Wong, K. Kwok, H. Chan
In this paper, the use of a lead magnesium niobate-lead titanate (PMN-PT) single crystal disk as a resonator has been explored. Finite element method (FEM) has been used to simulate both the impedance spectrum and vibration displacement for the PMN-PT disk. Because of the spurious modes, the disk with a full electrode or a partial electrode does not exhibit a clean resonance peak of the fundamental thickness mode vibration. However, a partial electrode can effectively confine the fundamental mode vibration in the electroded region, while the spurious mode vibration still spreads over the whole disk. By using an epoxy support along the edge, these spurious mode vibrations can be absorbed and a clean resonance response can be obtained. In addition to the excellent piezoelectric properties, the PMN-PT single crystal should be a promising material for resonator applications
{"title":"Study of PMN-PT Single Crystals for Resonator Applications","authors":"H. Wong, K. Kwok, H. Chan","doi":"10.1109/FREQ.2006.275447","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275447","url":null,"abstract":"In this paper, the use of a lead magnesium niobate-lead titanate (PMN-PT) single crystal disk as a resonator has been explored. Finite element method (FEM) has been used to simulate both the impedance spectrum and vibration displacement for the PMN-PT disk. Because of the spurious modes, the disk with a full electrode or a partial electrode does not exhibit a clean resonance peak of the fundamental thickness mode vibration. However, a partial electrode can effectively confine the fundamental mode vibration in the electroded region, while the spurious mode vibration still spreads over the whole disk. By using an epoxy support along the edge, these spurious mode vibrations can be absorbed and a clean resonance response can be obtained. In addition to the excellent piezoelectric properties, the PMN-PT single crystal should be a promising material for resonator applications","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121293324","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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