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2011 XXXth URSI General Assembly and Scientific Symposium最新文献

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Generic configurations for the SKA SKA的通用配置
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1109/URSIGASS.2011.6051206
R. Bolton, R. Millenaar
{"title":"Generic configurations for the SKA","authors":"R. Bolton, R. Millenaar","doi":"10.1109/URSIGASS.2011.6051206","DOIUrl":"https://doi.org/10.1109/URSIGASS.2011.6051206","url":null,"abstract":"We have developed generic layouts for both Phase 1 and Phase 2 of the Square Kilometre Array (SKA). We present these layouts here and show some examples of their sensitivity performance in the uv domain.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117050823","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}
引用次数: 0
Powered and active RF metamaterials 电源和有源射频超材料
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1109/URSIGASS.2011.6050640
S. Cummer, B. Popa, A. Katko
{"title":"Powered and active RF metamaterials","authors":"S. Cummer, B. Popa, A. Katko","doi":"10.1109/URSIGASS.2011.6050640","DOIUrl":"https://doi.org/10.1109/URSIGASS.2011.6050640","url":null,"abstract":"We report techniques for the design of active and tunable RF metamaterials and measurements of their novel properties, including frequency agile metamaterials in which each element is individually computer controlled with a nonvolatile state memory, powered active metamaterials containing embedded amplifiers, and parametrically pumped nonlinear active metamaterials.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"155 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117126118","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}
引用次数: 0
Comparison of electron density profiles extracted from DIAS maps and ionosonde measurements at Nicosia during low solar activity 太阳低度活动期间从DIAS地图提取的电子密度分布与尼科西亚电离探空仪测量值的比较
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1109/URSIGASS.2011.6050998
H. Haralambous
{"title":"Comparison of electron density profiles extracted from DIAS maps and ionosonde measurements at Nicosia during low solar activity","authors":"H. Haralambous","doi":"10.1109/URSIGASS.2011.6050998","DOIUrl":"https://doi.org/10.1109/URSIGASS.2011.6050998","url":null,"abstract":"This paper presents a comparison of electron density profiles derived from digital ionosonde measurements at the low-middle latitude European station in Nicosia, Cyprus (coordinates: 35°N, 33°E geographic) and the DIAS system at various heights (100,150,200,250,300,350,400 and 450 km). DIAS (European Digital Upper Atmosphere Server) is a service based on a pan-European digital data collection on the state of the upper atmosphere, which offers real-time information and historical data collections provided by most operating ionospheric stations in Europe. Hourly profiles were obtained using manually scaled data over Nicosia during the solar minimum period from January to December 2009. Hourly and monthly root mean squared error values (R.M.S.E) between Nicosia and DIAS maximum electron density values were also computed and comparisons of the observations were made.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117170345","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}
引用次数: 0
Simulation of ultrasound harmonic imaging as affected by tissue properties 组织特性对超声谐波成像影响的模拟
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1109/URSIGASS.2011.6050446
Jinhua Yu, Yuanyuan Wang, Jinglu Tan
{"title":"Simulation of ultrasound harmonic imaging as affected by tissue properties","authors":"Jinhua Yu, Yuanyuan Wang, Jinglu Tan","doi":"10.1109/URSIGASS.2011.6050446","DOIUrl":"https://doi.org/10.1109/URSIGASS.2011.6050446","url":null,"abstract":"Ultrasound harmonic imaging was simulated by numerically solving nonlinear acoustic equations for a given medium field and mimicking the B-mode scan procedures used in medical ultrasound imaging systems. The linear acoustic equations were extended to include relaxation dissipation and nonlinearity in compressibility. Pressure waves were induced by multiple transducer elements at the medium boundary and echoes from the medium field were simulated by using the finite difference time domain algorithm with absorbing boundary conditions. Simulation experiments showed the potential of simulation in analyzing ultrasound harmonic imaging process.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117197373","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}
引用次数: 2
Low phase noise microwave generation with fiber-based femtosecond lasers and applications 光纤飞秒激光器的低相位噪声微波产生及其应用
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1109/URSIGASS.2011.6050310
W. Zhang, T. Li, A. Haboucha, M. Lours, A. Luiten, R. Holzwarth, G. Santarelli, Y. Le Coq
{"title":"Low phase noise microwave generation with fiber-based femtosecond lasers and applications","authors":"W. Zhang, T. Li, A. Haboucha, M. Lours, A. Luiten, R. Holzwarth, G. Santarelli, Y. Le Coq","doi":"10.1109/URSIGASS.2011.6050310","DOIUrl":"https://doi.org/10.1109/URSIGASS.2011.6050310","url":null,"abstract":"When a femtosecond laser is servoed onto an ultra-stable cw laser, its repetition rate acquire an extreme spectral purity. By photodetecting the pulses, we are able to generate ultra-low phase noise microwave signals and use it for cutting edge metrology experiments. We present our past and present work to generate microwave signal with very low degradation from the limit imposed by the reference oscillator, using a highly reliable fiber-based system. The latest developments involve employing an intra-cavity electro-optic modulator (for increased servo bandwidth), reduced relative intensity noise of the laser, and studies of the photodetector amplitude to-phase conversion.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120977882","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}
引用次数: 0
The ALMA Photonic Local Oscillator system ALMA光子本振系统
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1117/12.927174
W. Shillue, W. Grammer, C. Jacques, R. Brito, J. Meadows, J. Castro, J. Banda, Y. Masui
{"title":"The ALMA Photonic Local Oscillator system","authors":"W. Shillue, W. Grammer, C. Jacques, R. Brito, J. Meadows, J. Castro, J. Banda, Y. Masui","doi":"10.1117/12.927174","DOIUrl":"https://doi.org/10.1117/12.927174","url":null,"abstract":"The Atacama Large Millimeter Array (ALMA) Central Local Oscillator (LO) system generates and distributes all of the LO and timing references for ALMA. These are used by the Front End and Back End Systems at the antenna, and by the Correlator in the central building. Due to the unprecedented combination of high sky frequencies (up to 950 GHz) and long baseline lengths of up to 15 kilometers, the ALMA 1st LO requirement is particularly stringent, with extremely precise timing and synchronization needed down to ∼10 femtosecond level. The unique requirements, design, and implementation of the ALMA LO system is reviewed and presented. Further, detailed design and performance data are given on the 1st LO reference, also called the “ALMA Photonic LO System.” The challenging phase coherence and drift requirements of the Photonic LO affected the design of all of its modules and subassemblies. The final system thus includes many novel and state-of-the-art optoelectronics and photonics modules. The system has been installed and is now in routine use supporting the ALMA Commissioning Science and Verification phase of the project.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121210473","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}
引用次数: 29
Analysis of cylindrically conformal patch antennas on isoimpedance anisotropic substrates 等阻抗各向异性基板上圆柱共形贴片天线的分析
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1109/URSIGASS.2011.6050686
H. Odabasi, F. Teixeira
{"title":"Analysis of cylindrically conformal patch antennas on isoimpedance anisotropic substrates","authors":"H. Odabasi, F. Teixeira","doi":"10.1109/URSIGASS.2011.6050686","DOIUrl":"https://doi.org/10.1109/URSIGASS.2011.6050686","url":null,"abstract":"We numerically investigate the performance of cylindrically conformal patch antennas on isoimpedance anisotropic substrates. These substrates are specifically designed to increase the effective (electrical) height without producingsurface waves.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127182683","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}
引用次数: 1
Estimation of the parameters of 2D Debye dispersive media using a time-domain inverse scattering technique 用时域逆散射技术估计二维德拜色散介质参数
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1109/URSIGASS.2011.6050370
T. G. Papadopoulos, I. Rekanos
{"title":"Estimation of the parameters of 2D Debye dispersive media using a time-domain inverse scattering technique","authors":"T. G. Papadopoulos, I. Rekanos","doi":"10.1109/URSIGASS.2011.6050370","DOIUrl":"https://doi.org/10.1109/URSIGASS.2011.6050370","url":null,"abstract":"A time-domain inverse scattering method for the reconstruction of inhomogeneous dispersive media described by the Debye model is presented. The estimation of the parameters characterizing the scatterer is based on the minimization of a cost function, which describes the discrepancy between measured and estimated values of the electric field. Applying the calculus of variations, we derive the Fréchet derivatives with respect to the scatterer properties, which can be utilized by any gradient-based optimization technique. Numerical results for the reconstruction of two-dimensional Debye scatterer using the Polak-Ribière algorithm exhibit the efficiency of the proposed method.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127282205","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}
引用次数: 1
Impact of direct-path wave on Imac in secret key agreement system using ESPAR antennas ESPAR天线密钥协议系统中直接路径波对Imac的影响
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1109/URSIGASS.2011.6050502
Tadafumi Yoshida, Takafumi Saito, Katsuhiro Fujiki, Kazumasa Uematsu, H. Uehara, T. Ohira
{"title":"Impact of direct-path wave on Imac in secret key agreement system using ESPAR antennas","authors":"Tadafumi Yoshida, Takafumi Saito, Katsuhiro Fujiki, Kazumasa Uematsu, H. Uehara, T. Ohira","doi":"10.1109/URSIGASS.2011.6050502","DOIUrl":"https://doi.org/10.1109/URSIGASS.2011.6050502","url":null,"abstract":"Current cryptography may be potentially decrypted by an extremely high performance computer. More secure key sharing schemes are expected. One possible solution is secret key agreement system which makes use of Electrically Steerable Parasitic Array Radiator (ESPAR) antenna. In this scheme ideally, by using wave propagation characteristics, eavesdropper cannot guess secret key from regular terminals. Actually however, eavesdropper has chances to guess the key if he is located on the line of direct-path wave between regular terminals. In our study, we evaluate the impact of direct-path wave on Information mutual anti-tapping condition (Imac) under a noisy channel.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125890596","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}
引用次数: 2
Atmospheric phase correction for ALMA with 183 GHz water vapour radiometers 183 GHz水蒸汽辐射计ALMA的大气相位校正
2011 XXXth URSI General Assembly and Scientific Symposium Pub Date : 2011-10-20 DOI: 10.1051/0004-6361/201220987
B. Nikolic, R. Bolton, S. Graves, R. Hills, J. Richer
{"title":"Atmospheric phase correction for ALMA with 183 GHz water vapour radiometers","authors":"B. Nikolic, R. Bolton, S. Graves, R. Hills, J. Richer","doi":"10.1051/0004-6361/201220987","DOIUrl":"https://doi.org/10.1051/0004-6361/201220987","url":null,"abstract":"One of the great challenges for ALMA is overcoming the natural limits set by the turbulence in the atmosphere to achieve resolutions as fine as ten milli-arcseconds. A critical component in the strategy to achieve this are mm-wave radiometers on each of the 12 m diameter telescopes that observe the emission from the atmospheric water vapour line at 183 GHz. The information from these radiometers can be used to compute the fluctuations in total water vapour along the line of sight of each telescope, and from this, the fluctuation in effective path to each antenna. The estimates of path fluctuations are then used to phase-rotate recorded visibilities leading to much increased coherence. In this paper we briefly review the design of the radiometers, describe the software processing steps to derive phase corrections and show some of the first results from the ALMA site in Chile.","PeriodicalId":325870,"journal":{"name":"2011 XXXth URSI General Assembly and Scientific Symposium","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126031734","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}
引用次数: 66
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