The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Adriano Camps - One of the best experts on this subject based on the ideXlab platform.
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normality analysis for rfi detection in microwave Radiometry
Remote Sensing, 2009Co-Authors: J M Tarongi, Adriano CampsAbstract:Radio-frequency interference (RFI) present in microwave Radiometry measurements leads to erroneous radiometric results. Sources of RFI include spurious signals and harmonics from lower frequency bands, spread-spectrum signals overlapping the “protected” band of operation, or out-of-band emissions not properly rejected by the pre-detection filters due to its finite rejection. The presence of RFI in the radiometric signal modifies the detected power and therefore the estimated antenna temperature from which the geophysical parameters will be retrieved. In recent years, techniques to detect the presence of RFI in radiometric measurements have been developed. They include time- and/or frequency domain analyses, or time and/or frequency domain statistical analysis of the received signal which, in the absence of RFI, must be a zero-mean Gaussian process. Statistical analyses performed to date include the calculation of the Kurtosis, and the Shapiro-Wilk normality test of the received signal. Nevertheless, statistical analysis of the received signal could be more extensive, as reported in the Statistics literature. The objective of this work is the study of the performance of a number of normality tests encountered in the Statistics literature when applied to the detection of the presence of RFI in the radiometric signal, which is Gaussian by nature. A description of the normality tests and the RFI detection results for different kinds of RFI are presented in view of determining an omnibus test that can deal with the blind spots of the currently used methods.
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the visibility function in interferometric aperture synthesis Radiometry
IEEE Transactions on Geoscience and Remote Sensing, 2004Co-Authors: I Corbella, N Duffo, M Vallllossera, Adriano Camps, F TorresAbstract:The fundamental equation of interferometric aperture synthesis Radiometry is revised to include full antenna pattern characterization and receivers' interaction. It is shown that the cross correlation between the output signals of a pair of receivers is a Fourier-like integral of the difference between the scene brightness temperature and the physical temperature of the receivers. The derivation is performed using a thermodynamic approach to account for the effects of mutual coupling between antenna elements. The analysis assumes that the receivers include ferrite isolators so that the noise wave passing from the receiver toward the antenna can be modeled as uncorrelated ambient noise. The effect of wide beamwidth antennas on the polarization basis of the retrieved brightness temperature is also discussed.
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radiometric sensitivity computation in aperture synthesis interferometric Radiometry
IEEE Transactions on Geoscience and Remote Sensing, 1998Co-Authors: Adriano Camps, I Corbella, Javier Bara, F TorresAbstract:This paper is concerned with the radiometric sensitivity computation of an aperture synthesis interferometric radiometer devoted to Earth observation. The impact of system parameters and the use of simultaneous redundant measurements are analyzed. The interferometric radiometer uncertainty principle is presented; it quantifies the relationship between radiometric sensitivity and angular resolution.
Paul R Stauffer - One of the best experts on this subject based on the ideXlab platform.
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Microwave Radiometry for noninvasive monitoring of brain temperature
Emerging Electromagnetic Technologies for Brain Diseases Diagnostics Monitoring and Therapy, 2018Co-Authors: Dario B. Rodrigues, Paul R Stauffer, Pedro Pereira, Paolo F MaccariniAbstract:Microwave Radiometry is a passive and noninvasive technique that is able to measure deep tissue temperature and track changes in thermal profiles in tissue up to 5 cm below the surface over several hours. These characteristics make microwave Radiometry a suitable technique to monitor brain temperature during extended hypothermic surgeries, and thus avoid potential complications that result from poorly controlled low temperature levels and return to normothermia. This chapter addresses all development stages of a radiometric brain thermometer including: radiometer electronics; antenna design and fabrication; power to temperature calibration algorithm; multilayer head phantom model with variable temperature compartments; experimental validation of sensor performance; and initial clinical implementation. In particular, a radiometric antenna is described based on a log-spiral design optimized in silico to receive energy from deep brain. The prototype is tested using a realistic head phantom that consists of an anatomical human skull with separate brain and scalp compartments in which tissue-equivalent fluid phantoms circulate at independent temperatures (32 °C for scalp and 37 °C for brain). Experimental data shows that the calculated radiometric brain temperature tracks within 0.4 °C the measured brain phantom temperature over a 4.6 h experiment, when the brain phantom is lowered 10 °C and then returned to original temperature. A clinical case confirms the ability to noninvasively monitor temperature in deep brain using microwave Radiometry, with radiometric measurements that closely track changes in core temperature as measured in the nasopharynx. Both simulated and experimental results demonstrate that a 1.1–1.6 GHz radiometric sensor with 2.5 cm diameter is an appropriate tool for noninvasive monitoring of deep brain temperature.
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detection of vesicoureteral reflux using microwave Radiometry system characterization with tissue phantoms
IEEE Transactions on Biomedical Engineering, 2011Co-Authors: Kavitha Arunachalam, Paolo F Maccarini, V De Luca, P Tognolatti, F Bardati, Brent W Snow, Paul R StaufferAbstract:Microwave (MW) Radiometry is proposed for passive monitoring of kidney temperature to detect vesicoureteral reflux (VUR) of urine that is externally heated by a MW hyperthermia device and thereafter reflows from the bladder to kidneys during reflux. Here, we characterize in tissue-mimicking phantoms the performance of a 1.375 GHz Radiometry system connected to an electromagnetically (EM) shielded microstrip log spiral antenna optimized for VUR detection. Phantom EM properties are characterized using a coaxial dielectric probe and network analyzer (NA). Power reflection and receive patterns of the antenna are measured in layered tissue phantom. Receiver spectral measurements are used to assess EM shielding provided by a metal cup surrounding the antenna. Radiometer and fiberoptic temperature data are recorded for varying volumes (10-30 mL) and temperatures (40-46°C) of the urine phantom at 35 mm depth surrounded by 36.5°C muscle phantom. Directional receive pattern with about 5% power spectral density at 35 mm target depth and better than -10 dB return loss from tissue load are measured for the antenna. Antenna measurements demonstrate no deterioration in power reception and effective EM shielding in the presence of the metal cup. Radiometry power measurements are in excellent agreement with the temperature of the kidney phantom. Laboratory testing of the Radiometry system in temperature-controlled phantoms supports the feasibility of passive kidney thermometry for VUR detection.
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characterization of a digital microwave Radiometry system for noninvasive thermometry using a temperature controlled homogeneous test load
Physics in Medicine and Biology, 2008Co-Authors: Kavitha Arunachalam, Paul R Stauffer, Paolo F Maccarini, S Jacobsen, F SterzerAbstract:Microwave Radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave Radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. Performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7–4.2GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30–50°C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6mm thickness is also investigated. To assess clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075°C resolution and standard deviation of 0.217°C for homogeneous and layered tissue loads at temperatures between 32–45°C. Within the 3.7–4.2GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band Radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial hyperthermia applicators.
G Ulm - One of the best experts on this subject based on the ideXlab platform.
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a quarter century of metrology using synchrotron radiation by ptb in berlin
Physica Status Solidi B-basic Solid State Physics, 2009Co-Authors: Burkhard Beckhoff, Alexander Gottwald, M Richter, R Klein, Michael Krumrey, R Muller, Frank Scholze, R Thornagel, G UlmAbstract:For more than 25 years, the Physikalisch-Technische Bundesanstalt has been strongly engaged in the field of metrology using synchrotron radiation. In Berlin, this research programme started together with the user operation of the electron storage ring BESSY I in the early 1980s. At the beginning, the work was focused on fundamental Radiometry, i.e. using the storage ring as a primary radiation source standard and operating beamlines for source and detector calibration in the vacuum ultraviolet spectral range. Meanwhile, at the electron storage rings BESSY II and Metrology Light Source in Berlin-Adlershof, the activities have been extended to a broad range of fundamental and applied photon metrology in the range from the far infrared to hard X-rays, including methods like cryogenic Radiometry, reflectometry and X-ray fluorescence spectroscopy. In the present review, we give a short historical introduction to this work, describe our laboratories and the basic radiometric principles, and present examples of recent applications, largely performed within the framework of scientific cooperations with external partners from industry and research. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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Radiometry with synchrotron radiation
Metrologia, 2003Co-Authors: G UlmAbstract:Electron storage rings are nearly ideal radiation sources for Radiometry over a broad spectral range from the infrared to the x-ray region. Many national metrology institutes make extensive use of synchrotron radiation for Radiometry. The Synchrotron Ultraviolet Radiation Facility SURF III, which has recently been upgraded, is used by the National Institute of Standards and Technology (NIST), and the Physikalisch-Technische Bundesanstalt (PTB) operates a European Radiometry laboratory at the third-generation storage ring BESSY II. The storage rings are used as calculable broadband radiation sources (primary source standards) and in combination with primary detector standards as sources of continuously tunable monochromatic radiation for detector calibration. The use of cryogenic electrical-substitution radiometers as primary detector standards has made it possible to considerably extend high-accuracy calibrations from the ultraviolet (UV) to the x-ray regime. Radiometry in the extreme UV (EUV) range, and in particular reflectometry, has become increasingly important for the development of EUV lithography. An overview of synchrotron radiation based Radiometry will be given.
Andreas Mandelis - One of the best experts on this subject based on the ideXlab platform.
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photothermal Radiometry measurement of thermophysical property change of an ion irradiated sample
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2012Co-Authors: Kyle Horne, Andreas Mandelis, Heng Ban, Anna MatvienkoAbstract:Abstract Using photothermal Radiometry (PTR) an ion-irradiated ZrC sample's thermal properties are measured by fitting frequency-scan data to a theoretical model for the surface temperature. The technique is shown to measure thermal properties without physical contact of a very small sample.
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Thermal-wave radar: A novel subsurface imaging modality with extended depth-resolution dynamic range
Review of Scientific Instruments, 2009Co-Authors: Nima Tabatabaei, Andreas MandelisAbstract:Combining the ideas behind linear frequency modulated continuous wave radars and frequency domain photothermal Radiometry (PTR), a novel PTR method is introduced. Analytical solutions to the heat diffusion problem for both opaque and transparent solids are provided. Simulations and experimental results suggest a significant improvement in the dynamic range when using the thermal-wave radar (TWR) instead of conventional PTR. A practical TWR image resolution augmentation method is proposed.
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photothermal Radiometry with solid cylindrical samples
Journal of Applied Physics, 2004Co-Authors: Chinhua Wang, Andreas Mandelis, Yue LiuAbstract:We extend the applications of the photothermal diagnostics by means of laser-infrared photothermal Radiometry (PTR) to samples with curved surfaces. Specifically, we present both the theoretical and experimental PTR studies on solid cylindrical samples (surfaces). Based on the Green function method, the thermal-wave field distribution of a cylindrical surface that is under the excitation of a periodically modulated uniform beam is obtained. The laser beam, which is of a cylindrical symmetry, impinges uniformly, partially or fully, on the cylindrical surface, which is practically infinitely long along the axial direction. The characteristics of the thermal-wave field with respect to the thermal diffusivity of the material, the diameter of the sample, the size of the incident beam, and the measurement of the angle are discussed. Experimental results are in good agreement with the theory.
Vincent Masse - One of the best experts on this subject based on the ideXlab platform.
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comparing and optimizing ultraviolet germicidal irradiation systems use for patient room terminal disinfection an exploratory study using Radiometry and commercial test cards
Antimicrobial Resistance and Infection Control, 2018Co-Authors: Vincent Masse, Michael J Hartley, Michael B Edmond, Daniel J DiekemaAbstract:Ultraviolet germicidal irradiation (UVGI) systems are gaining popularity, however objective comparisons of their characteristics are lacking. While environmental cultures and reduction of hospital-associated infections rates are excellent study endpoints, they are impractical for centers with limited resources who want to compare or optimize UVGI systems use. We evaluated Radiometry and commercial test cards, two simple and low cost tools, to compare 2 full size UVGI systems (Tru-D and Optimum-UV Enlight) and 2 small units (Lumalier EDU 435 and MRSA-UV Turbo-UV). Radiometry-derived output curves show that if both large devices emit enough energy to reach C. difficile lethal doses at 10 ft, the reduction in output in distance is almost perfectly logarithmic. In a patient room environment, Enlight and Tru-D performed similarly when compared using Radiometry and commercial test cards. The two small devices reached C. difficile range around the bathroom with the device raised above the floor, but longer times are needed. Despite different workflows and price points, no clear superiority emerges between Tru-D and Enlight. Bathroom disinfection should be dealt with separately from the main room and small, cheaper units can be used. Radiometry and commercial test cards are promising ways to compare UVGI systems, but further validation is needed using correlation with environmental cultures. Not applicable.
