Pub Date : 2006-06-04DOI: 10.1109/FREQ.2006.275474
J. Prestage, S. Chung, T. Le, L. Lim, L. Maleki
The authors have recently completed a breadboard ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture the authors have demonstrated short-term stability ~2-3times10-13 at 1 second, averaging to 10-15 at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1-2times10 -13 at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for nearly a year with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow a ~400 C tube bake-out to prepare for tube seal-off. This approach to the vacuum follows the methods used in flight vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved. They use neon as a buffer gas with 2-3 times less pressure induced frequency pulling than helium and, being heavier, negligible diffusion losses will occur over the operation lifetime
{"title":"Progress Toward a 10-15 Stable Ion Clock for Deep Space Applications","authors":"J. Prestage, S. Chung, T. Le, L. Lim, L. Maleki","doi":"10.1109/FREQ.2006.275474","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275474","url":null,"abstract":"The authors have recently completed a breadboard ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture the authors have demonstrated short-term stability ~2-3times10-13 at 1 second, averaging to 10-15 at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1-2times10 -13 at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for nearly a year with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow a ~400 C tube bake-out to prepare for tube seal-off. This approach to the vacuum follows the methods used in flight vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved. They use neon as a buffer gas with 2-3 times less pressure induced frequency pulling than helium and, being heavier, negligible diffusion losses will occur over the operation lifetime","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133399648","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 : 2006-06-04DOI: 10.1109/FREQ.2006.275327
E. Rubiola
Craig Nelson received his BSEE from the University of Colorado in Boulder in 1990. After working in the optical disk market and co-founding SpectraDynamics, he joined the staff at the Time and Frequency Division of the National Institute of Standards and Technology. He has worked on synthesis and control electronics, as well as software for both the NIST7 and F1 primary frequency standards. He is presently involved in research and development of ultra-stable synthesizers, low phase noise electronics, and phase noise metrology. Current areas of research include high-speed pulsed phase noise measurements and phase noise metrology in the 100 GHz range. He has published over 20 papers and frequently presents tutorials on the practical aspects of high-resolution phase noise metrology.
{"title":"Tutorial Session 2A - The Leeson Effect: Phase Noise in Feedback Oscillators","authors":"E. Rubiola","doi":"10.1109/FREQ.2006.275327","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275327","url":null,"abstract":"Craig Nelson received his BSEE from the University of Colorado in Boulder in 1990. After working in the optical disk market and co-founding SpectraDynamics, he joined the staff at the Time and Frequency Division of the National Institute of Standards and Technology. He has worked on synthesis and control electronics, as well as software for both the NIST7 and F1 primary frequency standards. He is presently involved in research and development of ultra-stable synthesizers, low phase noise electronics, and phase noise metrology. Current areas of research include high-speed pulsed phase noise measurements and phase noise metrology in the 100 GHz range. He has published over 20 papers and frequently presents tutorials on the practical aspects of high-resolution phase noise metrology.","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133568224","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 : 2006-06-04DOI: 10.1109/FREQ.2006.275433
F. Sthal, E. Bigler, J. Maisonnet, R. Bourquin, B. Dulmet
The goal of this paper is to investigate the possibility of temperature-compensated cuts for both kinds of vibrations in Langasite resonators. We propose theoretical and experimental investigations of vibrating beam resonators with a rectangular cross-section in extensional and flexural modes for Langasite. Measures of frequency-temperature effects in beam vibrating in length extension are given
{"title":"Langasite beam resonators: Theoretical and experimental investigations","authors":"F. Sthal, E. Bigler, J. Maisonnet, R. Bourquin, B. Dulmet","doi":"10.1109/FREQ.2006.275433","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275433","url":null,"abstract":"The goal of this paper is to investigate the possibility of temperature-compensated cuts for both kinds of vibrations in Langasite resonators. We propose theoretical and experimental investigations of vibrating beam resonators with a rectangular cross-section in extensional and flexural modes for Langasite. Measures of frequency-temperature effects in beam vibrating in length extension are given","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116480421","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 : 2006-06-04DOI: 10.1109/FREQ.2006.275337
F. Josse
This tutorial will cover devices based on piezoelectric crystals and used for materials characterization and sensor applications. Various acoustic wave devices used for physical and bio-chemical sensing applications will be presented and described. The course will then focus on two types of piezoelectric sensors that have reached some level of maturity – available as commercial products or under development. They are the thickness shear mode (TSM) resonators and surface acoustic wave (SAW) devices (both Rayleigh SAW and shear horizontal-SAW) used for sensing in gas and/or liquid phase. Devices with selective absorptive coatings will be described. The electronic/electrical characteristics of the sensor devices will be given. Sensor device principles, design parameters, operating characteristics, and key sensing parameters will be covered. Various measurement schemes used with the piezoelectric sensors will be described.
{"title":"Tutorial Session 4C - Piezoelectric Sensors as Electronic/electrical Devices","authors":"F. Josse","doi":"10.1109/FREQ.2006.275337","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275337","url":null,"abstract":"This tutorial will cover devices based on piezoelectric crystals and used for materials characterization and sensor applications. Various acoustic wave devices used for physical and bio-chemical sensing applications will be presented and described. The course will then focus on two types of piezoelectric sensors that have reached some level of maturity – available as commercial products or under development. They are the thickness shear mode (TSM) resonators and surface acoustic wave (SAW) devices (both Rayleigh SAW and shear horizontal-SAW) used for sensing in gas and/or liquid phase. Devices with selective absorptive coatings will be described. The electronic/electrical characteristics of the sensor devices will be given. Sensor device principles, design parameters, operating characteristics, and key sensing parameters will be covered. Various measurement schemes used with the piezoelectric sensors will be described.","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116516794","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 : 2006-06-04DOI: 10.1109/FREQ.2006.275350
P. Sotiriadis
Diophantine frequency synthesis is a new approach to fine-step, fast-hopping, low-spurs frequency synthesis that is based on mathematical properties of integer numbers and linear Diophantine equations. Diophantine frequency synthesis overcomes the constraining relation between frequency step and phase-comparator frequency inherent in conventional phase-locked loops. It leads to fine-step, fast-hopping, modular-structured frequency synthesizers with potentially very low spurs, especially in the vicinity of the carrier
{"title":"Diophantine Frequency Synthesis A Number Theory Approach to Fine Frequency Synthesis","authors":"P. Sotiriadis","doi":"10.1109/FREQ.2006.275350","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275350","url":null,"abstract":"Diophantine frequency synthesis is a new approach to fine-step, fast-hopping, low-spurs frequency synthesis that is based on mathematical properties of integer numbers and linear Diophantine equations. Diophantine frequency synthesis overcomes the constraining relation between frequency step and phase-comparator frequency inherent in conventional phase-locked loops. It leads to fine-step, fast-hopping, modular-structured frequency synthesizers with potentially very low spurs, especially in the vicinity of the carrier","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"137 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116290291","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 : 2006-06-04DOI: 10.1109/FREQ.2006.275469
M. Tobar, P. Stanwix, A. Fowler, E. Ivanov, J. Hartnett, C. Locke, P. Wolf
The authors present current work at the University of Western Australia to test fundamental physics using precision phase and frequency measurements. The authors describe two experiments under development. Firstly, they describe a continuously rotating cryogenic microwave oscillator constructed to test local Lorentz invariance (LLI). Initial results improve limits set by previous non-rotating experiments by about an order of magnitude with only 3 months of data. Now, with over a year of data, they have reduced the noise floor by a factor of two. Secondly, they describe the development of a new, magnetically asymmetric, microwave interferometer with thermal noise limited readout, which will allow a sensitivity to the scalar and odd-parity coefficients for Lorentz violation in the photon sector of the standard model extension of parts in 108 and 1012 respectively
{"title":"Using Precision Oscillators and Interferometers to Test Fundamental Physics","authors":"M. Tobar, P. Stanwix, A. Fowler, E. Ivanov, J. Hartnett, C. Locke, P. Wolf","doi":"10.1109/FREQ.2006.275469","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275469","url":null,"abstract":"The authors present current work at the University of Western Australia to test fundamental physics using precision phase and frequency measurements. The authors describe two experiments under development. Firstly, they describe a continuously rotating cryogenic microwave oscillator constructed to test local Lorentz invariance (LLI). Initial results improve limits set by previous non-rotating experiments by about an order of magnitude with only 3 months of data. Now, with over a year of data, they have reduced the noise floor by a factor of two. Secondly, they describe the development of a new, magnetically asymmetric, microwave interferometer with thermal noise limited readout, which will allow a sensitivity to the scalar and odd-parity coefficients for Lorentz violation in the photon sector of the standard model extension of parts in 108 and 1012 respectively","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128472611","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.2006.275360
Qingming Chen, Qing-Ming Wang
Piezoelectric AlN thin film has been considered for fabricating the thin film bulk acoustic wave resonator (FBAR) for over years. Characterization of thin film material properties including density, elastic modulus, and piezoelectric coefficient are essential in processing study and for predicting the performance of the acoustic wave devices. In this paper, the authors present our results on the fabrication of highly c-axis oriented AlN thin films on Pt/Ti/Si (100) and Pt/Ti/sapphire (002) substrates by DC reactive magnetron sputtering method. The crystalline structure and the surface morphology of AlN films were characterized by scanning electron microscopy (SEM). The effective piezoelectric coefficient d33eff of the AlN films on the sapphire substrate were measured by the laser interferometer method and the piezoelectric coefficient d33 was calculated. In addition, a more detailed characterization on the mechanical properties was performed by using a recently developed resonance spectrum method. Based on the impedance spectrum, the density and elastic constant of the piezoelectric AlN thin film in the four-layer composite resonator structure were evaluated. The calculated results reveal that the piezoelectric coefficient d33, density and velocity of the AlN thin film are 4.19pm/V, 3187.3kg/m3, and 10631m/s respectively
{"title":"Characterization of Mechanical and Piezoelectric Properties of the AlN Thin Film in a Composite Resonator Stuctrue","authors":"Qingming Chen, Qing-Ming Wang","doi":"10.1109/FREQ.2006.275360","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275360","url":null,"abstract":"Piezoelectric AlN thin film has been considered for fabricating the thin film bulk acoustic wave resonator (FBAR) for over years. Characterization of thin film material properties including density, elastic modulus, and piezoelectric coefficient are essential in processing study and for predicting the performance of the acoustic wave devices. In this paper, the authors present our results on the fabrication of highly c-axis oriented AlN thin films on Pt/Ti/Si (100) and Pt/Ti/sapphire (002) substrates by DC reactive magnetron sputtering method. The crystalline structure and the surface morphology of AlN films were characterized by scanning electron microscopy (SEM). The effective piezoelectric coefficient d33eff of the AlN films on the sapphire substrate were measured by the laser interferometer method and the piezoelectric coefficient d33 was calculated. In addition, a more detailed characterization on the mechanical properties was performed by using a recently developed resonance spectrum method. Based on the impedance spectrum, the density and elastic constant of the piezoelectric AlN thin film in the four-layer composite resonator structure were evaluated. The calculated results reveal that the piezoelectric coefficient d33, density and velocity of the AlN thin film are 4.19pm/V, 3187.3kg/m3, and 10631m/s respectively","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"22 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":"127298144","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.2006.275363
C. Ayela, T. Leichlé, C. Bergaud, L. Nicu, É. Cattan, C. Soyer, M. Pugnière
The paper is about 4 times 4 matrices of piezoelectric membranes that were fabricated by standard micromachining techniques starting with silicon-on-insulator (SOI) wafer. Each membrane (circular shaped) can be individually addressed for actuation and sensing applications through a PbZr(x)Ti(1-x)O3 (PZT) 800-nm thick film. The main objective of this work is to study the dynamic behavior of the piezoelectric membranes in air and liquid media. The results showed high quality factors in air (up to 150) and in water-glycerol (lowered by a factor 4 for a glycerol proportion in water less than 30%) while the resonant frequencies were significantly decreased by the liquid apparent added mass effects
{"title":"High quality factors of silicon membranes with piezoelectric actuation and detection scheme for biosensing purpose in liquid media","authors":"C. Ayela, T. Leichlé, C. Bergaud, L. Nicu, É. Cattan, C. Soyer, M. Pugnière","doi":"10.1109/FREQ.2006.275363","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275363","url":null,"abstract":"The paper is about 4 times 4 matrices of piezoelectric membranes that were fabricated by standard micromachining techniques starting with silicon-on-insulator (SOI) wafer. Each membrane (circular shaped) can be individually addressed for actuation and sensing applications through a PbZr(x)Ti(1-x)O3 (PZT) 800-nm thick film. The main objective of this work is to study the dynamic behavior of the piezoelectric membranes in air and liquid media. The results showed high quality factors in air (up to 150) and in water-glycerol (lowered by a factor 4 for a glycerol proportion in water less than 30%) while the resonant frequencies were significantly decreased by the liquid apparent added mass effects","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"241 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":"123259863","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.2006.275377
D. Shah, C. Klemenz
In this paper, development of a new control system for the growth of crystals by Czochralski and potential impact on crystal quality are presented. This research has been carried out as an aspect of optimization for the growth of high-quality large diameter langasite type crystals. Initial results and experimental setup for LGT (La3 Ga5.5Ta0.5O14) are discussed
{"title":"Adaptive Control System for Czochralski Growth of Large-diameter Langasite-type Crystals","authors":"D. Shah, C. Klemenz","doi":"10.1109/FREQ.2006.275377","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275377","url":null,"abstract":"In this paper, development of a new control system for the growth of crystals by Czochralski and potential impact on crystal quality are presented. This research has been carried out as an aspect of optimization for the growth of high-quality large diameter langasite type crystals. Initial results and experimental setup for LGT (La<sub>3 </sub>Ga<sub>5.5</sub>Ta<sub>0.5</sub>O<sub>14</sub>) are discussed","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"1 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":"128705306","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.2006.275456
L. Arceo-Miquel, Y. Shmaliy, J. Munoz-Diaz, O. Ibarra-Manzano
The trade-off is investigated experimentally between the real-time unbiased FIR estimates of the time interval error (TIE) model of a local clock and the sawtooth correction implemented to the measurement set. We exploit the crystal oscillator embedded to the Stanford Frequency Counter SR620 as a local clock and rubidium oscillator attached to SR625 as a reference clock. The SynPaQ III GPS Sensor is used as the GPS timing receiver. We show that the unbiased FIR estimates produce a lower error than the sawtooth correction. The error becomes much lower when the TIE changes very slowly. The unbiased FIR estimates of the fractional frequency offset are consistent to the rubidium measurements and produce much lower noise than in the measurements with the sawtooth correction
实验研究了本地时钟时间间隔误差(TIE)模型的实时无偏FIR估计和对测量集实施锯齿校正之间的权衡。我们利用嵌入斯坦福频率计数器SR620的晶体振荡器作为本地时钟，并利用附加在SR625上的铷振荡器作为参考时钟。GPS授时接收机采用SynPaQ III GPS Sensor。结果表明，无偏FIR估计比锯齿校正产生更低的误差。当TIE变化非常缓慢时，误差就会小得多。分数频率偏移的无偏FIR估计与铷测量结果一致，并且产生的噪声比锯齿校正的测量结果低得多
{"title":"Experimental Comparison of the Unbiased FIR Estimates vs. the Sawtooth Correction in GPS-based Timekeeping","authors":"L. Arceo-Miquel, Y. Shmaliy, J. Munoz-Diaz, O. Ibarra-Manzano","doi":"10.1109/FREQ.2006.275456","DOIUrl":"https://doi.org/10.1109/FREQ.2006.275456","url":null,"abstract":"The trade-off is investigated experimentally between the real-time unbiased FIR estimates of the time interval error (TIE) model of a local clock and the sawtooth correction implemented to the measurement set. We exploit the crystal oscillator embedded to the Stanford Frequency Counter SR620 as a local clock and rubidium oscillator attached to SR625 as a reference clock. The SynPaQ III GPS Sensor is used as the GPS timing receiver. We show that the unbiased FIR estimates produce a lower error than the sawtooth correction. The error becomes much lower when the TIE changes very slowly. The unbiased FIR estimates of the fractional frequency offset are consistent to the rubidium measurements and produce much lower noise than in the measurements with the sawtooth correction","PeriodicalId":445945,"journal":{"name":"2006 IEEE International Frequency Control Symposium and Exposition","volume":"1 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":"129896415","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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