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Over the last two decades, there has been a notable increase in the use of bistatic radar configurations for remote sensing, particularly employing Signals-of-Opportunity (SoOp), such as Global Navigation Satellite System - Reflectometry (GNSS-R). Unlike the more common monostatic backward radar configuration, GNSS-R forward scattering is dominated by different mechanisms. The forward scattering measurement provides valuable insights into regions where the backscatter is minimal or dominated by the double bounce effect caused by the vegetation. The Soil Moisture Active Passive (SMAP) mission carries an L-band radiometer and a radar. However, following a radar malfunction during its commissioning, the radar was repurposed to measure GPS L2C signals. This repurposing provides a unique opportunity to compare data from both the SMAP radar and GNSS-R (SMAP-R) collected by the same platform, using the same antenna, same incident angle, and similar frequencies. The study conducted offers a comprehensive analysis, both qualitative and quantitative, of the relationship between forward scattering at full polarization, and backward scattering at three polarizations (3-polarization: HH, VV and HV). Additionally, the study includes comparisons with ancillary geophysical measurements across three distinct areas with varying environmental characteristics, including dense forests and deserts. • There is a strong correlation between polarimetric GNSS-R and L-band radar. • Polarimetric GNSS-R provides complementary sensitivity over densely vegetated regions. • The relationship between forward and backward scattering is proportional but inverse. • Radar and reflectometry measurements complement each other over distinct areas. [ABSTRACT FROM AUTHOR]

• Electron-density diagnosis of the POINT system on the EAST was evaluated. • Experiment and simulation system VVUQ was applied to an entire plasma diagnostic system. • Uncertainties were identified, quantified, and minimized. • POINT system become a high-precision electron-density diagnostic system for the EAST. The verification, validation, and uncertainty quantification (VVUQ) analysis is a systematic method for identifying and quantifying uncertainties in complex engineering projects. This method has been used by the International Atomic Energy Agency as a critical assessment method in the field of high-precision plasma diagnostics in tokamaks. Starting from the basic theory to the final results, it assesses every process to obtain the uncertainties, system confidence level, and similarity between the model and experimental assessments. In this study, we evaluated the electron-density diagnosis of the polarimeter/interferometer system on an experimental advanced superconducting tokamak using a cylindrical simulation model. This study applied the VVUQ to an entire plasma diagnostic system for the first time, coupled with the statistical concepts of confidence and similarity. Through the VVUQ process, the uncertainty from the simulation code, diagnostic code, and engineering errors were identified, quantified, and minimized. [ABSTRACT FROM AUTHOR]

Microwave Tomography Imaging System (MwTIS) is an emerging tool for medical diagnosis in the non-invasive screening process. This paper addresses the ill-condition problem by proposing two new schemes incorporated into the DBIM image reconstructed algorithm for high frequencies in MwTIS. The first scheme is to propose an optimal step frequency using the degree of ill-posedness value for reducing the frequency diversity problem. The second scheme is to propose Krylov Subspace-based regularization method called Flexible Preconditioned Conjugate Gradient Least Square (FPCGLS) method to resolve the ill-condition problem. The iteratively updated preconditioner matrix in the proposed FP-CGLS method reduces the number of iterations and it is stable in high-level Gaussian noise. The efficiency of the proposed FP-CGLS method is validated by imposing Gaussian noise up to 30% in scattered breast phantom in the multifrequency range of 2 GHz -3 GHz It achieves an enhanced reconstructed image at 12 iterations with a relative error of 0.1802 for 20% of Gaussian noise and for the same scheme the existing CGLS method has a 0.4480 relative error at the 77 iterations. Further, the FP-CGLS along with the DBIM method produces a reconstructed image with the accuracy of 0.8760 in four DBIM iterations. [ABSTRACT FROM AUTHOR]

To investigate the behavior of plasma generated in the shock tube, microwave reflectometry is proposed to extract the permittivity $\epsilon _{r}$ of plasma. To remove the influence of parasitic reflections caused by the surroundings, a calibration process is introduced and the unknown calibration coefficients are determined by utilizing microwave interferometry as the reference technique. The shock tube is modeled as a three-layered medium to calculate the reflection coefficient. A time-dependent reconstruction algorithm is applied and theoretically validated to eliminate the multiple solutions in the inverse problem. By comparing the permittivities extracted with microwave reflectometry and interferometry, the effects of plasma diffusion are demonstrated with a modified analytical model in the beginning time region of experiments. In addition, the nonuniform flow in the generated plasma located near the end time region is also observed. The determination of the effective time region for electron density $N_{e}$ and collision frequency $v_{e}$ extraction is discussed as well. Finally, the differences between microwave reflectometry and interferometry in terms of averaged $N_{e}$ < $1{\times }10^{17} m^{-3}$ and averaged $v_{e}$ < $1.5{\times }10^{9} s^{-1}$ are investigated in the effective time region

A novel approach in addressing cyclone global navigation satellite system (CyGNSS) intersatellite and GPS-related calibration issues is proposed, based on a track-wise $\sigma ^{o}$ bias correction method. This method makes use of both ancillary data from numerical weather prediction models and a semiempirical geophysical model function. Care is taken, so the track-wise $\sigma ^{o}$ bias correction maintains CyGNSS signal sensitivity. Both intersatellite and GPS-related calibration issues are removed after correction. Long-term $\sigma ^{o}$ downward trend, observed throughout the CyGNSS mission, is greatly reduced. Using the corrected $\sigma ^{o}$ measurements, a wind retrieval method is also presented and its product thoroughly assessed for a three-year period against European Centre for Medium-Range Weather Forecasts (ECMWFs), Advanced Scatterometer (ASCAT) A/B, Advanced Microwave Scanning Radiometer (AMSR)-2, GMI, WindSat, hurricane weather research and forecasting (HWRF) model, and the stepped frequency microwave radiometer (SFMR) winds. The overall wind speed bias and standard deviation of the error (stde) against ECMWF are 0.16 and 1.19 m/s, while these are −0.11 and 1.12 m/s against ASCAT A/B, respectively. The same metrics against AMSR-2/GMI/WindSat (combined) are −0.19 and 1.11 m/s, respectively. The bias and stde against soil moisture active passive (SMAP) are −0.38 and 1.90 m/s, respectively. In the tropical cyclone environment, the bias and stde against HWRF are −0.54 and 2.90 m/s, and −4.71 and 5.88 m/s with SFMR. Finally, CyGNSS wind performance is gauged in the presence of rain. Below 10 m/s, the bias between CyGNSS and ECMWF increases as the rain rate increases. Between 10 and 15 m/s, biases are mostly absent. Above 15 m/s, results are inconclusive due to the low number of collocated rain samples. Overall, the presented CyGNSS wind speed product both exhibits consistency and reliability, showing promise of using GNSS-R derived winds for operational purposes. [ABSTRACT FROM AUTHOR]

When providing solutions for lighting of streets, the parameters must comply with some predefined standards. One of these standards is the standard for EN 13201:2015. Performance requirements - This part of this European Standard that defines performance requirements which are specified as lighting classes for road lighting aiming at the visual needs of road users, and it considers environmental aspects of road lighting. [ABSTRACT FROM AUTHOR]

In this paper, a novel method for accurate modeling of microstrip discontinuities based on pulse shaping modulation is presented. The proposed method uses a novel excitation signal to address typical challenges when utilizing conventional TDR using Gaussian pulse excitation. In the first step a Double-Exponential Pulse (DEP) is utilized in a modified TDR system to improve the discontinuity localization precision as it has a sharp rise time. Second, a Linear Frequency Modulated (LFM) signal is used to provide more energy at higher frequencies in contrast with the conventional TDR. Subsequently, a mixed DEP and LFM signals are utilized to combine both advantages: high precision of DEP, and the accuracy of LFM. Simulated results are presented to explore the potential of the proposed method. [ABSTRACT FROM AUTHOR]

Monitoring intra-abdominal pressure (IAP) has become a standard in intensive care units. Correlation between the abdominal wall's thickness (AWTh) and IAP has been reported previously. The abdominal wall can be modeled as a compound of parallel dielectric slabs; changes in their width have a direct effect on the reflection coefficient of the abdominal wall at microwave frequencies. This work describes the design of a reflectometry system and its proof-of-concept trial on five patients during laparoscopic surgery. The system complies with IEEE Std. C95.1-2005 concerning exposure of humans to microwave electromagnetic fields in controlled environments. The results putatively show an inverse correlation between IAP and the reflection coefficient, and a strong dependence on the body mass index. A better understanding of the dynamics in the changes of the AWTh (during intra-abdominal hypertension) will allow further development of a microwave-based technique for the continuous non-invasive indirect monitoring of IAP in critical patients. [ABSTRACT FROM AUTHOR]

Reentry plasma sheath diagnostic plays extremely important roles in the research of the blackout problem. In this paper, a broadband microwave reflectometer based on the invariant point of reflection data has been designed and developed for the reentry plasma sheath diagnostic. The invariant point Y(ωp, 1) is derivable from the broadband reflection data. The electron density and collision frequency are measured simultaneously. The diagnostic algorithm was verified by the simulation analysis and diagnostic experiment. The algorithm has low computational complexity and relatively high precision. This algorithm offers a certain reference value for the plasma sheath diagnostic of reentry vehicles or hypersonic vehicles in the future. Especially, the design of broadband VVD antenna with heat-resistant wave-transparent composites has certain practical values. [ABSTRACT FROM AUTHOR]

• A 13-channel far-infrared (FIR) laser Polarimeter/Interferometer has been designed for the HL-3 tokamak, including eight horizontally-viewing channels and five oblique channels. • The novel structure of support tower allows us to arrange multi-channel light-path on both sides. • Multichannel line-integral electron densities have been successfully measured by the interferometric measurement in 2023, with a time resolution of <1.0 microsecond. The interferometer system will be upgraded to the three-wave based Polarimeter/Interferometer. Aiming to achieve important parameters of the electron density and plasma current density profile, a multi-channel far-infrared (FIR) laser Polarimeter/Interferometer is being developed for HL-3 tokamak by using the formic-acid laser source (HCOOH, λ=432.5 μm). All the 13 probing channels were distributed in two columns, including eight horizontally-viewing channels and five oblique channels. The stainless steel support tower (7.0 m high) was specially designed, and itself novel structure allowed us to arrange the light-paths of horizontal channels and oblique channels on two sides, respectively. Copper corner-cube-reflector (CCR) was mounted in the vacuum vessel to retrace the incident wave. In 2023, multi-channel line-integral electron densities were successfully derived by the interferometric measurement, with a time resolution of 1.0μs, line-integral density resolution of ∼5.0 × 1016/cm2. Right now, the interferometer system is being upgraded to three-wave based Polarimeter/Interferometer, which is able to simultaneously measure the electron density and Faraday rotation angle. [ABSTRACT FROM AUTHOR]

Glass fiber reinforced polymer (GFRP) laminates are extensively used across various engineering fields. However, the occurrence of internal delamination defects during its production and usage can severely jeopardize equipment safety. Consequently, there's a pressing need to quantitatively detect both the thickness and depth (i.e., the distance from the delamination defects to the GFRP laminates' surface) of these delamination defects. To date, most research efforts fall short in providing an evaluation method that concurrently addresses both defect thickness and depth. In this study, we introduce a far-field quantitative evaluation method based on microwave propagation theory. Unique microwave reflection signals emerge due to variations in defect thickness and depth. By utilizing these distinct signals and incorporating parameters such as signal frequency, defect dimensions, GFRP plate thickness, and its permittivity, we developed a model that relates echo signals to defect characteristics. This model serves as an effective tool for defect detection and quantification. Simulations and experiments validate that our method can simultaneously detect and quantify defect depth and thickness through a single reflection signal. By monitoring changes in microwave reflectivity amplitude, we successfully detected and quantified delamination defect of 30 μm. The quantitative error for defect depth remains below 0.15 mm, with an average error of 0.048 mm. Meanwhile, the error for defect thickness does not exceed 10 μm, averaging at 3.75 μm. Importantly, the theoretical minimum detectable value can reach several microns. Furthermore, this method's detection accuracy remains little affected by the stand-off distance, offering a notable advantage in practical applications. [ABSTRACT FROM AUTHOR]

The Lunar Flashlight cubesat mission was designed and flown to collect new data on the abundance and distribution of water ice frost in lunar permanently shadowed regions (PSRs) using active laser spectroscopy. Key advantages of active spectroscopy are that it can collect surface reflectance data in locations and conditions where passive spectroscopy cannot operate, specifically nightside locations where no indirect lighting is available, and in the deepest parts of PSRs where indirect lighting may be too faint for passive spectroscopy. Lunar Flashlight launched in 2022 but because of a propulsion system failure, did not make it to the Moon to conduct its science investigation. However, Lunar Flashlight proved to be an extremely successful technology demonstration mission, meeting or exceeding all its technology-focused mission goals, including demonstrating its instrument functionality. This paper describes the extensive ground and test campaigns to characterize the Lunar Flashlight laser reflectometer instrument and its planned utility for science observations, along with recommendations for future instrument design, development, verification, and use. • The Lunar Flashlight mission lasted from December 2022 to June 2023. • As a Technology Demonstration mission, Lunar Flashlight met all its technology goals. • Despite not reaching the Moon, the Lunar Flashlight laser spectroscopy payload was successfully tested. • The payload ground and flight performance data can be used for future instrument development. [ABSTRACT FROM AUTHOR]

• The dispersion interferometer based on CO 2 laser was developed for Globus-M2 tokamak. • Time resolution = 20 μs, spatial resolution = 0.02 m, measurement accuracy ≤ 1017 m −2. • During the year long operation, DI has proven to be reliable diagnostic at Globus-M2. • It is planned to use DI measurements for plasma density stabilizing in Globus-M2. The dispersion interferometry diagnostic (DI) based on the CO 2 -laser was commissioned at the Globus-M2 tokamak for absolute measurements of the line-integrated electron density (IED) along the chord in the equatorial plane. IED measurement error corresponding to the intrinsic noise of the acquisition device was below 1017 m −2 with time and spatial resolution 20µs and 2 cm, respectively. Inference of the IED using the second harmonic interference was done by means of spectral algorithm. Execution of the algorithm is performed at the FPGA in real-time mode. During the year long operation, DI was proven to be reliable and robust IED diagnostic at Globus-M2. [ABSTRACT FROM AUTHOR]

Microwave reflectometry, having its origins in ionosphere probing techniques to evaluate electronic density, has become one of the most important diagnostics for the same quantity in fusion plasmas. Reflectometry will play a major role in next-generation machines, in particular in DEMO, where it is expected to provide plasma positioning, shaping, and tracking data. The ability to have an ever-increasing comprehensive description of reflectometry is particularly important since it allows us to assess the measuring capabilities of existing experimental systems and to predict the performance of new diagnostic concepts based on probing waves. Furthermore, wave propagation in a thermonuclear plasma with fluctuating electronic densities is far from straightforward and the need for a numerical full-wave treatment becomes fundamental. We will present the reader with the fundamentals of this technique and introduce the usage and evolution of FDTD in reflectometry, using as an example, the synthetic diagnostics setup that uses the family of REFMUL* codes, which is employed in the assessment of the performance of several reflectometry systems in different fusion machines. [ABSTRACT FROM AUTHOR]

Global navigation satellite system reflectometry (GNSS-R) has found many applications in the field of Earth observation including ocean wind-speed detection, ice altimetry, soil moisture monitoring, and more. The main focus of GNSS-R research to date has been on forward-scattered reflections, but theoretical work has proposed a backscattering regime and associated new application opportunities, including marine target detection. This article discusses the methods and results of processing the U.K. TechDemoSat-1 raw data collections in a backscattering regime for the first time, with initial results from sea ice datasets presented. The research has also identified a key problem with the backscatter method-for certain geometries the power from the specular point (forward scattered) may contaminate the data. The theory behind this and a method for predicting such occurrences is also discussed.

A portable fast chirp frequency-modulated continuous-wave (FMCW) reflectometer is presented to locate and monitor fast varying discontinuities or faults on transmission lines. This frequency-domain reflectometry (FDR) approach exploits and adapts the advantages of the closely related and frequently employed FMCW radar principle to transmission line reflectometry and overcomes the limitations of commonly used time-domain reflectometry (TDR) methods. The signal generation is based on direct digital synthesis (DDS) and frequency multiplication in order to exploit the advantages of DDS technology, e.g., fast and agile sweep time, and to overcome the drawbacks of analog signal sources related to nonlinearities, temperature sensitivity, or phase noise. By this means, the presented reflectometer provides highly linear, broadband, and fast swept chirp pulses with a duration on the order of microseconds with an initial frequency in the lower UHF-band and a bandwidth of 5.2 GHz. The system concept, its hardware realization, and performance specifications are introduced. The first laboratory test results for static transmission lines and a dynamic measurement setup are presented. The results demonstrate the effectiveness, versatility, and fine ranging capabilities on the order of 2 cm of this approach. [ABSTRACT FROM AUTHOR]

In this work, an innovative system for structural health monitoring of metallic pipes is presented. The proposed system relies on using the pipeline as a waveguide for the propagation of an electromagnetic (EM) signal; possible anomalies in the pipe provoke the partial reflection of the propagating EM signal. Different from previous works that address similar applications, in this work, the EM test signal is injected in the pipeline/waveguide through a coaxial/waveguide transition that is made on the pipe surface (rather than on a cross section as generally done). In practical applications, this strategy would allow connecting more easily the test equipment to the operating, buried pipes. In addition, because reflections caused by anomalies may be difficult to identify with adequate accuracy, the authors have developed a dedicated processing strategy for the analysis of the reflections caused by anomalies. More specifically, by analyzing the measured reflected signal and correlating it to the ideal reflected signal, it is possible to improve the localization of anomalies along the pipe. The proposed system, along with the processing and operating strategies, was validated through full-wave simulations and experimental tests carried out on a steel pipe in the presence of intentionally provoked anomalies. [ABSTRACT FROM AUTHOR]

Microwave reflectometry diagnostics have been widely used to measure density profiles in fusion plasma. However, the high sensitivity of the diagnostics to plasma turbulence often results in large radial deviations in the edge density profile and causes difficulty in profile evaluation. To improve the performance of profile evaluation, a modified RANdom SAmple Consensus (RANSAC) method has been applied to fit the density profiles measured by reflectometry on the experimental advanced superconducting tokamak. Compared with the traditional least-squares method, the modified RANSAC method is much more efficient and robust in fitting the experimental profiles. Furthermore, a combination of RANSAC and a genetic algorithm (GA-RANSAC) is used to further optimize the profile evaluation procedure. The results show that this GA-RANSAC method yields better performance and stabler convergence than the modified RANSAC alone. [ABSTRACT FROM AUTHOR]

This review presents an overview of previously reported non-invasive intra-abdominal pressure (IAP) measurement techniques. Each section covers the basic physical principles and methodology of the various measurement techniques, the experimental results, and the advantages and disadvantages of each method. The most promising non-invasive methods for IAP measurement are microwave reflectometry and ultrasound assessment, in combination with an applied external force. [ABSTRACT FROM AUTHOR]

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Although most types of room-temperature THz detectors involving photothermoelectric (PTE) elements operate in a relatively narrow frequency band due to their antenna-coupled structure, such detectors may be implemented on the basis of non-resonant structures with broadband response due to broadband nature of PTE effect. This work is devoted to improvement of PTE detector sensitivity using serial connection of PTE elements consisting of bismuth-antimony thin films and Cu electrodes. The responsivity of this detector is studied at the frequency of 140 GHz. It is shown that the average voltage produced by PTE detector reaches up to 0.6 mV and is 15 times higher than one produced by continuous film consisting of the same material, while the maximum rate of voltage change is 17 times higher in comparison with continuous film response. Noise equivalent power (NEP) of PTE detector based on Bi 1-x Sb x /Cu branches is equal to 12.6 nW H z − 0. 5 , and noise equivalent temperature difference (NETD) is equal to 4.9 m °C. This detector may be applied in the field of THz and microwave photonics in scanning security systems, THz signal detection in wireless communications, imaging and diagnostics in medicine, food industry and material characterization. • Non-resonant THz PTE detector was implemented using Bi 88 Sb 12 /Cu thermoelectric. • Bi 88 Sb 12 /Cu-based detector consists of 18 series-connected thermoelectric branches. • Average thermo-EMF produced by the detector reaches up to 0.6 mV. • NEP and NETD of the detector are equal to 12.6 nW Hz − 0. 5 and 4.9 m °C. [ABSTRACT FROM AUTHOR]

In this paper, we propose a cost-effective laser frequency locking scheme based on frequency modulation spectroscopy (FMS) for precision measurements and experiments in various fields. We demonstrate that by digitally modulating the detected signal frequency using a Field-Programmable-Gate-Array (FPGA) driven by a home-built lock-in and a proportional–integral–derivative (PID) control system, our system achieves higher precision, user-friendliness, and versatility. Our system generates a 20 V peak-to-peak amplified voltage to a piezo transducer (PZT), which enables a mode-hop free laser scan of approximately 2 ±0.2 GHz. We directly modulate the detected saturation absorption signal with a sinusoidal waveform, then demodulate it to obtain multiple zero crossing locking points on the D2 transition of Cs at 852.35 nm. We optimized the system for three commonly used atomic transitions and found that researchers can select any of the zero crossing peaks for frequency stabilization depending on their experimental requirements, we locked the laser at the crossover transition. We measured the long-time frequency fluctuation and power spectral density and found that the frequency fluctuation of the laser is much less than the natural line width of the D2 transition of Cs. Our results demonstrate that our laser frequency locking scheme is effective and practical for precision measurements and experiments in various fields. • Compact in dimension leads to very portable. • Modified FPGA leads to large scanning frequency range. • Output voltage can be regulated in positive voltage leads to protection of PZT. • Laser frequency stabilized less natural linewidth of the transition. [ABSTRACT FROM AUTHOR]

Intra-abdominal hypertension, defined as an intra-abdominal pressure (IAP) equal to or above 12 mmHg is one of the major risk-factors for increased morbidity (organ failure) and mortality in critically ill patients. Therefore, IAP monitoring is highly recommended in intensive care unit (ICU) patients to predict development of abdominal compartment syndrome and to provide a better care for patients hospitalized in the ICU. The IAP measurement through the bladder is the actual reference standard advocated by the abdominal compartment society; however, this measurement technique is cumbersome, non-continuous, and carries a potential risk for urinary tract infections and urethral injury. Using microwave reflectometry has been proposed as one of the most promising IAP measurement alternatives. In this study, a novel radar-based method known as transient radar method (TRM) has been used to monitor the IAP in an in vitro model with an advanced abdominal wall phantom. In the second part of the study, further regression analyses have been done to calibrate the TRM system and measure the absolute value of IAP. A correlation of –0.97 with a p-value of 0.0001 was found between the IAP and the reflection response of the abdominal wall phantom. Additionally, a quadratic relation with a bias of −0.06 mmHg was found between IAP obtained from the TRM technique and the IAP values recorded by a pressure gauge. This study showed a promising future for further developing the TRM technique to use it in clinical monitoring.

We investigated the evolution of HS Hya system's inclination based on analysis of its light curves in the period 1964–2021. HS Hya is EA type eclipsing binary star, belonging to separate group with changing orbital inclination. We used our recent observations as well as the data from sky surveys. [ABSTRACT FROM AUTHOR]

This work presents a microwave reflectometry-based system for monitoring large concrete structures (during the curing process and also while the structure is in use), through the combined use of punctual and diffused sensing elements. In particular, the adoption of punctual probes on a reference concrete specimen allows the development of an innovative and accurate calibration procedure, useful to obtain the value of the water content on a larger structure made of the same material. Additionally, a wire-like diffused sensing element can be permanently embedded in buildings and used to monitor the structure along the entire length of the sensing element. The adopted diffused sensing element can be used not only to detect dielectric variation during the curing process, but also throughout the service life of the structure. The combined use of punctual and diffused sensing elements represents an important innovation from a procedural point of view, able to provide detailed and quantitative information on the health status of the structure both during and after construction.

In this paper, we present noncontact and noninvasive vital signal detection using a microwave reflectometer. Elimination of noise components due to random movement of human subjects has been the biggest issue for microwave measurement. Appropriate filtering, amplitude control of the reflectometer signal, and cross correlation among multiple reflectometers together with new algorithms have enabled motion artifact elimination, signal peak detection, and data processing for various parameters related to heart rate (HR) and heart rate variability (HRV). We focus here on the real time measurements of instantaneous HR and HRV for practical use. The evaluation by microwave reflectometry is completely noninvasive and feasible even through clothing, which is extremely effective for health maintenance in daily life as well as for preventing sudden death related to, for example, coronary heart disease and ventricular arrhythmia. [ABSTRACT FROM AUTHOR]

The reflectometry system on experimental advanced superconducting tokamak (EAST) is undergoing an upgrade for more comprehensive measurement of plasma density profile and fluctuation. The data acquisition and control system (DACS) has been redeveloped to satisfy the upgraded requirements. The profile reflectometry works in 30–110 GHz (X-mode) and 40–90 GHz (O-mode), when the fluctuation reflectometry operates at 20 fixed frequency points in 50–110 GHz (X-mode) and 20–60 GHz (O-mode). The PXIe-based DACS includes two 8-channel 14-bit 250 MSPS digitizers and ten 8-channel 12-bit 60 MSPS digitizers. A self-developed five-channel 250 MSPS arbitrary waveform generator (AWG) is used to control voltage control oscillators for frequency sweeping. A trigger and clock manager and a timing module receive the trigger and clock signal from the central controller and synchronize all the digitizers and the AWG. The total data rate from digitizers is 2515 MB/s. The data from digitizers is streamed to a disk array (RAID 0) with the data throughput capacity of 3000 MB/s. Meanwhile, the selected data are transported to an FPGA-based real-time data processing module, which utilize a pretrained neural network to calculate the plasma density profile. Now, the new reflectometry is being installed on EAST, and its performance is tested preliminarily in the 2018 experimental campaign. [ABSTRACT FROM AUTHOR]

An O-mode microwave reflectometry system has been developed to measure the density fluctuation on Zheda Plasma Experiment Device (ZPED). The microwave frequency range of this diagnostic system is from 10 GHz to 18 GHz, corresponding to the cutoff densities from 0.13×1019m-3 to 0.4×1019m-3. The density fluctuations are measured with a fixed microwave frequency for plasma in different magnetic field. It has been observed that the density fluctuation power changes with the magnetic field nonlinearly: the density fluctuations increase linearly with the magnetic field when the magnetic field is less than the critical magnetic field, while almost no change when the magnetic field is larger than the critical magnetic field. [ABSTRACT FROM AUTHOR]

The characteristic frequencies of a system provide important information on the phenomena that govern its physical properties. In this framework, there has recently been renewed interest in cryogenic microwave characterization for condensed matter systems since it allows to probe energy scales of the order of a few μeV. However, broadband measurements of the absolute value of a sample response in this frequency range are extremely sensitive to its environment and require a careful calibration. In this paper, we present an in situ calibration method for cryogenic broadband microwave reflectometry experiments that is both simple to implement and through which the effect of the sample electromagnetic environment can be minimized. The calibration references are provided here by the sample itself, at three reference temperatures where its impedance is assumed or measured, and not by external standards as is usual. We compare the frequency-dependent complex impedance (0.1–2 GHz) of an a-Nb15Si85 superconducting thin film obtained through this Sample-Based Calibration (SBC) and through an Open-Short-Load Standard Calibration (SC) when working at a very low temperature (0.02–4 K) and show that the SBC allows us to obtain the absolute response of the sample. This method brings the calibration planes as close as possible to the sample, so that the environment electrodynamic response does not affect the measurement, provided it is temperature independent. This results in a heightened sensitivity, for a given experimental set–up. [ABSTRACT FROM AUTHOR]

The goal of light transport acquisition is to take images from a sparse set of lighting and viewing directions, and combine them to enable arbitrary relighting with changing view. While relighting from sparse images has received significant attention, there has been relatively less progress on view synthesis from a sparse set of "photometric" images---images captured under controlled conditions, lit by a single directional source; we use a spherical gantry to position the camera on a sphere surrounding the object. In this paper, we synthesize novel viewpoints across a wide range of viewing directions (covering a 60° cone) from a sparse set of just six viewing directions. While our approach relates to previous view synthesis and image-based rendering techniques, those methods are usually restricted to much smaller baselines, and are captured under environment illumination. At our baselines, input images have few correspondences and large occlusions; however we benefit from structured photometric images. Our method is based on a deep convolutional network trained to directly synthesize new views from the six input views. This network combines 3D convolutions on a plane sweep volume with a novel per-view per-depth plane attention map prediction network to effectively aggregate multi-view appearance. We train our network with a large-scale synthetic dataset of 1000 scenes with complex geometry and material properties. In practice, it is able to synthesize novel viewpoints for captured real data and reproduces complex appearance effects like occlusions, view-dependent specularities and hard shadows. Moreover, the method can also be combined with previous relighting techniques to enable changing both lighting and view, and applied to computer vision problems like multiview stereo from sparse image sets. [ABSTRACT FROM AUTHOR]

A supersonic molecular beam injection modulation experiment with a developed 11-channel polarimeter-interferometer has been performed on EAST. The particle deposition was determined by the edge density profile measured by microwave reflectometry. The particle transport coefficient profiles in low- and high-density discharges including low confinement and the high confinement mode (L mode and H mode) have been obtained by fitting the line-integrated modulation amplitude and phase profiles. The results show that in ohmic discharge, the difference between the edge and center diffusion coefficients is small compared to that in L and H modes. For convection velocity, the edge coefficients are several times larger than the center coefficients. However, this discrepancy is small in ohmic discharge. The H mode is characterized by a large inward convective velocity at the plasma edge which coincides with the steep pedestal. [ABSTRACT FROM AUTHOR]

Microwave and millimeter-wave reflectometry, a form of continuous-wave surface penetrating radar, is an emerging nondestructive inspection technique that is suitable for nonmetallic pipelines. This paper shows a $K$ -band microwave reflectometry instrument implemented onto an in-line pipe-crawling robot, which raster-scanned cracks and external wall loss on a high-density polyethylene (HDPE) pipe of diameter 150 mm and wall thickness 9.8 mm. The pipe was scanned with three environments surrounding the pipe that approximated the use cases of overground HDPE pipelines, plastic-lined metal pipes, and undersea HDPE pipelines. The instrument was most sensitive when cracks were oriented parallel to its magnetic (H) plane. Any small variation in the standoff distance between the instrument’s probe antenna and the pipe wall, which was not easy to avoid, was found to obscure the image. To mitigate this problem, a sensitivity analysis showed that an optimal frequency can be chosen at which standoff distance can vary by up to ±0.75 mm within a certain range without distorting the indications of defects on the image. [ABSTRACT FROM AUTHOR]

For microwave reflectometry-based fusion plasma diagnostics, the acquired data is contaminated by the surrounding noise environment, making it difficult to measure the beat frequency accurately. Discrete wavelet and wavelet packet transforms are unsuitable as the former cannot decompose detailed coefficients, and the latter is a time-variant transform. This paper presents a correlation-based Maximal Overlap Discrete Wavelet Packet Transform (MODWPT), which decomposes the signal using different mother wavelet families. The suitable mother wavelet is chosen based on the metrics like signal-to-noise ratio (SNR), peak signal-to-noise ratio (PSNR), mean squared error (MSE), and mean absolute error (MAE). The data used for analysis is the stationary tokamak wall, for which the beat frequency and distance are measured. After rigorous analysis, it is found that sym12 outperforms with the following values 0.0493 (MSE), 0.1736 (MAE), 4.3334(SNR(dB)), 13.0634(PSNR(dB)) respectively. This technique can be extended to plasma scenarios for accurately measuring beat frequency and density profile. • MODWPT analyses fusion-tokamak back wall data. • Correlation-based sub-bands selection after wavelet decomposition for noise removal. • sym12 wavelet is appropriate for the back wall data analysis. • Outcome can be used for accurate density profile measurement in plasma scenarios. [ABSTRACT FROM AUTHOR]

Acknowledgments I wish to thank all of the authors and peer reviewers for their valuable contributions to this Special Issue, "Development and Applications of Microwave/Millimeter Wave Diagnostics in Industry". Microwave/millimeter wave devices and systems have been developed as core technologies in the fields of communication and measurement. The purpose of this Special Issue is to introduce recent advancements in microwave/millimeter wave diagnostic technologies and the current status of their applications. [Extracted from the article]

Highlights • There is a physical link between SRP albedo-area and observed albedo-area. • The same BRDFs must be used to model both SRP force and light curves. • Data fusion is key in estimating mass and albedo-area of an RSO. Abstract There are many Resident Space Objects (RSOs) in the Geostationary Earth Orbit (GEO) regime, both operational and debris. The primary non-gravitational force acting on these RSOs is Solar Radiation Pressure (SRP), which is sensitive to the RSO's area-to-mass ratio. Sparse observation data and mismodeling of non-gravitational forces has constrained the state of practice in tracking and characterizing RSOs. Accurate identification, characterization, tracking, and motion prediction of RSOs is a high priority research issue as it shall aid in assessing collision probabilities in the GEO regime, and orbital safety writ large. Previous work in characterizing RSOs has taken a preliminary step in exploiting fused astrometric and photometric data to estimate the RSO mass, shape, attitude, and size. This works, in theory, since angles data are sensitive to SRP albedo-area-to-mass ratio, and photometric data are sensitive to shape, attitude, and observed albedo-area. By fusing these two data types, mass and albedo-area both become observable parameters and can be estimated as independent quantities. However, previous work in mass and albedo-area estimation has not quantified and assessed the fundamental physical link between SRP albedo-area and observed albedo-area. The observed albedo-area is always a function of the SRP albedo-area along the line of sight of the observer. This is the physical relationship that this current research exploits. It is shown through simulation that due to this physical link, and through the fusion of astrometric and photometric data, it is possible to observe the mass of a space object when the area is not known. Results for data from 100 trajectories generated from randomly sampled initial conditions are shown. It is seen that even when the area of the object is not known, the uncertainty in mass can be lowered from an initial value of 800 kg to the range 500–700 kg for 72% of the samples, 200–500 kg for 13% of the samples, and 0–200 kg for 15% of the samples. It is further shown that although the uncertainties are large, the actual errors in mass are much lower, with the error RMS being less than 100 kg for 30% of the samples, between 100 and 200 kg for another 30%, and between 200 and 300 kg for 24% of the samples. [ABSTRACT FROM AUTHOR]

A cyclone global navigation satellite system (CYGNSS) $\sigma _o$ calibration analysis is presented using version 2.0 of the Level 1 dataset available on PO.DAAC. Three separate analyzes are conducted, namely, an examination of the specular bin location (in delay) and $\sigma _o$ relationship, an investigation of the impact of recently improved characterizations of the GPS effective isotropically radiated power on CYGNSS $\sigma _o$ , and an intersatellite $\sigma _o$ calibration analysis. We first noted a correlation between the specular delay bin location and $\sigma _o$ , where an increase in the specular delay bin resulted in an increase in $\sigma _o$ regardless of the wind speed level; a specular delay bin location ranging from 4.75 to 5.00 and from 7.00 to 7.25 resulted in a 14.74 and 17.72 dB median $\sigma _o$ , respectively. Noticeable improvements in the median $\sigma _o$ were present in the version 2.0 dataset, when separating the data by GPS block type: for blocks IIR, IIF, and IIR-M, median $\sigma _o$ were 15.39, 15.42, and 15.10 dB, respectively (compared to 19.38, 20.53, and 21.38 dB in version 1.1). Finally, an unexpected correlation between the instrument noise floor and $\sigma _o$ was observed for all eight observatories while conducting the intersatellite $\sigma _o$ calibration analysis. Approximately 0–1 dB absolute $\sigma _o$ difference biases (with up to $\sim$ 1 dB standard deviation) between spacecrafts were observed. A report of this analysis was presented to CYGNSS scientists and engineers, who eventually found an issue with the D/A DDM scaling algorithm. We expect better statistical performances in future releases of the data. [ABSTRACT FROM AUTHOR]

Photometric detection plays a significant role in microfluidics technology. However, the mismatch between the solution concentration and the optical path length will increase detection error. In this study, we proposed a round microfluidic chip for concentration detection to obtain the continuous gradient distribution of concentration. The optimum absorbance can be found by dynamic accurately searching. The solution concentration will be accurately calculated finally according to the relationship between arc length and solution concentration. The overall detection process runs automatically. Under the optimization of injection velocity and concentration, the experimental result shows that the compensation ratio increases as the solution concentration increases. The compensation ratio in the detection of pesticide residue has already reached 14.22% and the reproducibility is acceptable. Therefore, this novel method lays the theoretical foundation for the research of high precision microfluidic photometric detection equipment. [ABSTRACT FROM AUTHOR]

Stellar variability from pulsations and granulation presents a source of correlated noise that can impact the accuracy and precision of multiband photometric transit observations of exoplanets. This can potentially cause biased measurements in the transmission or emission spectrum or underestimation of the final error bars on the spectrum. ARIEL is a future space telescope and instrument designed to perform a transit spectroscopic survey of a large sample of exoplanets. In this paper, we perform simulations to assess the impact of stellar variability arising from pulsations and granulation on ARIEL observations of GJ 1214b and HD 209458b. We take into account the correlated nature of stellar noise, quantify it, and compare it to photon noise. In the range 1.95–7.8 |$\mu$| m, stellar pulsation and granulation noise has insignificant impact compared to photon noise for both targets. In the visual range, the contribution increases significantly but remains small in absolute terms and will have minimal impact on the transmission spectra of the targets studied. The impact of pulsation and granulation will be greatest for planets with low scale height atmospheres and long transit times around bright stars. [ABSTRACT FROM AUTHOR]

E-science of photometric data requires automatic procedures and a precise recognition of periodic patterns to perform science as well as possible on large data. Analytical equations that enable us to set the best constraints to properly reduce processing time and hence optimize signal searches play a crucial role in this matter. These are increasingly important because the production of unbiased samples from variability indices and statistical parameters has not been achievable so far. We discuss the constraints used in periodic signals detection methods as well as the uncertainties in the estimation of periods and amplitudes. The frequency resolution necessary to investigate a time series is assessed with a new approach that estimates the necessary sampling resolution from shifts on the phase diagrams for successive frequency grid points. We demonstrate the underlying meaning of the oversampling factor. We reassess the frequency resolutions required to find the variability periods of EA stars and use the new resolutions to analyse a small sample of EA upCatalina stars, i.e. EA stars previously classified as having insufficient number of observations at the eclipses. As a result, the variability periods of four EA upstars were determined. Moreover, we have a new approach to estimate the amplitude and period variations. From these estimations, information about the intrinsic variations of the sources is obtained. For a complete characterization of the light-curve signal, the period uncertainty and period variation must be determined. Constraints on periodic signal searches were analysed and delimited. [ABSTRACT FROM AUTHOR]

A very long-term near-infrared variable star survey towards the Large and Small Magellanic Clouds (LMC and SMC) was carried out using the 1.4 m InfraRed Survey Facility at the South African Astronomical Observatory. This project was initiated in 2000 December in the LMC, and in 2001 July in the SMC. Since then an area of 3 deg2along the bar in the LMC and an area of 1 deg2in the central part of the SMC have been repeatedly observed. This survey is ongoing, but results obtained with data taken until 2017 December are reported in this paper. Over more than 15 yr we have observed the two survey areas more than one hundred times. This is the first survey that provides near-infrared time-series data with such a long time baseline and on such a large scale. This paper describes the observations in the SMC and publishes a point source photometric catalogue, a variable source catalogue, and time-series data. [ABSTRACT FROM AUTHOR]

We present a study of the high-resolution optical spectrum for the hot post-asymptotic giant branch (post-AGB) star, Hen 3−1013, identified as the optical counterpart of the infrared source IRAS 14331−6435. For the first time, the detailed identifications of the observed absorption and emission features in the wavelength range 3700–9000 Å is carried out. Absorption lines of H i, He i, C i, N i, O i, Ne i C ii, N ii, O ii, Si ii, S ii, Ar ii, Fe ii, Mn ii, Cr ii, Ti ii, Co ii, Ni ii, S iii, Fe iii, and S iv were detected. From the absorption lines, we derived heliocentric radial velocities of V r= −29.6 ± 0.4  km s−1. We have identified emission permitted lines of O i, N i, Fe ii, Mg ii, Si ii, and Al ii. The forbidden lines of [N i ], [Fe ii ], [Cr ii ], and [Ni ii ] have been identified also. Analysis of [Ni ii ] lines in the gaseous shell gives an estimate for the electron density N e∼ 107cm−3and the expansion velocity of the nebula V exp= 12  km s−1. The mean radial velocity as measured from emission features of the envelope is V r= −36.0 ± 0.4 km s−1. The Balmer lines H α, H β, and H γ show P Cyg behaviour which indicate ongoing post-AGB mass loss. Based on ASAS and ASAS-SN data, we have detected rapid photometric variability in Hen 3−1013 with an amplitude up to 0.2 mag in the V band. The star's low-resolution spectrum underwent no significant changes from 1994 to 2012. Based on archival data, we have traced the photometric history of the star over more than 100 yr. No significant changes in the star brightness have been found. [ABSTRACT FROM AUTHOR]

We present a catalogue of distances, masses, and ages for ∼3 million stars in the second Gaia data release with spectroscopic parameters available from the large spectroscopic surveys: APOGEE, Gaia -ESO, GALAH, LAMOST, RAVE, and SEGUE. We use a Bayesian framework to characterize the probability density functions of distance, mass, and age using photometric, spectroscopic, and astrometric information, supplemented with spectroscopic masses where available for giant stars. Furthermore, we provide posterior extinction estimates (AV) to every star using published extinction maps as a prior input. We provide an appendix with extinction coefficients for Gaia photometry derived from stellar models, which account for variation with intrinsic colour and total extinction. Our pipeline provides output estimates of the spectroscopic parameters, which can be used to inform improved spectroscopic analysis. We complement our catalogues with Galactocentric coordinates and actions with associated uncertainties. As a demonstration of the power of our catalogue, we produce velocity dispersion profiles of the disc separated by age and Galactocentric radius (between 3 and |$15\, \mathrm{kpc}$| from the Galactic centre). This suggests that the velocity dispersion profiles flatten with radius in the outer Galaxy (⁠|$\gt\!8\, \mathrm{kpc}$|⁠) and that at all radii the velocity dispersion follows the smooth power law with age observed in the solar neighbourhood. [ABSTRACT FROM AUTHOR]

We present a sub-arcsecond crossmatch of Gaia DR2 against the INT Photometric H α Survey of the Northern Galactic Plane Data Release 2 (IPHAS DR2) and the Kepler -INT Survey (KIS). The resulting value-added catalogues (VACs) provide additional precise photometry to the Gaia photometry (r, i, and H α for IPHAS, with additional U and g for KIS). In building the catalogue, proper motions given in Gaia DR2 are wound back to match the epochs of IPHAS DR2, thus ensuring high proper motion objects are appropriately crossmatched. The catalogues contain 7927 224 and 791 071 sources for IPHAS and KIS, respectively. The requirement of >5σ parallax detection for every included source means that distances out to 1–1.5 kpc are well covered. We define two additional parameters for each catalogued object: (i) f c, a magnitude-dependent tracer of the quality of the Gaia astrometric fit; (ii) f FP, the false-positive rate for parallax measurements determined from astrometric fits of a given quality at a given magnitude. Selection cuts based on these parameters can be used to clean colour–magnitude and colour–colour diagrams in a controlled and justified manner. We provide both full and light versions of the VAC, with VAC-light containing only objects that represent our recommended trade-off between purity and completeness. Uses of the catalogues include the identification of new variable stars in the matched data sets, and more complete identification of H α-excess emission objects due to separation of high-luminosity stars from the main sequence. [ABSTRACT FROM AUTHOR]

Bile acids are considered a sensitive indicator for liver function in mammals and birds, and protein electrophoresis is a routine test used in mammals to differentiate inflammatory responses. The objective of this study was to establish reference intervals for bile acids and protein electrophoresis in clinically healthy panther chameleons (Furcifer pardalis) under similar husbandry conditions. Blood samples from 84 captive panther chameleons were collected in January and August from the ventral coccygeal vein and processed for protein capillary zone electrophoresis and enzymatic–photometric measurements of bile acids. Reference intervals for bile acids were similar to other reptile species, but those for protein electrophoresis differed considerably, with α-globulins as the second most predominant fraction after albumin. Significant differences between males and females were found in α1- and γ-globulin fractions. Three diseased panther chameleons that died within a few months after sampling had an albumin–globulin ratio below the reference interval. [ABSTRACT FROM AUTHOR]

An experimental test on the ability to observe an extrasolar planetary transit using limited photometric equipment from an Earth based Amateur Observatory. [ABSTRACT FROM AUTHOR]

Abstract We present an analysis of high-resolution imaging of an exoplanet by a meter-class telescope positioned at a real image of the exoplanet created by the solar gravity lens. We assume an exoplanet viewed in full phase and a simple deconvolution method to correct for the intrinsic blur caused by aberrations in the solar gravity lens, and account for the foreground light of the solar corona. We derive equations for the measurement times required for the telescope to produce such a high-resolution image, and find that due to shot noise considerations these times are large compared to human lifespans. We also discuss how measurement times could potentially be significantly shorter for exoplanets with special orbital and rotational parameters. Highlights • The solar corona greatly increases imaging times needed at the solar gravity lens. • High measurement precision is needed to construct solar gravity lens images. • Hundreds of years are likely needed to image exoplanets at the solar gravity lens. [ABSTRACT FROM AUTHOR]