scholarly journals The Balloon-Borne Investigation of Temperature and Speed of Electrons in the Corona (BITSE): Mission Description and Preliminary Results

Solar Physics ◽  
2021 ◽  
Vol 296 (1) ◽  
Author(s):  
N. Gopalswamy ◽  
J. Newmark ◽  
S. Yashiro ◽  
P. Mäkelä ◽  
N. Reginald ◽  
...  
Keyword(s):  
Heliocentric Distance ◽  
Signal To Noise Ratio ◽  
Flow Speed ◽  
Science Data ◽  
Uncertainty Interval ◽  
Heliospheric Observatory ◽  
Flash Storage ◽  
Goddard Space Flight Center ◽  
Good Agreement ◽  
Polarization Camera

AbstractWe report on the Balloon-borne Investigation of Temperature and Speed of Electrons in the corona (BITSE) mission launched recently to observe the solar corona from $\approx 3$ ≈ 3  Rs to 15 Rs at four wavelengths (393.5, 405.0, 398.7, and 423.4 nm). The BITSE instrument is an externally occulted single stage coronagraph developed at NASA’s Goddard Space Flight Center in collaboration with the Korea Astronomy and Space Science Institute (KASI). BITSE used a polarization camera that provided polarization and total brightness images of size $1024 \times 1024$ 1024 × 1024 pixels. The Wallops Arc Second Pointer (WASP) system developed at NASA’s Wallops Flight Facility (WFF) was used for Sun pointing. The coronagraph and WASP were mounted on a gondola provided by WFF and launched from the Fort Sumner, New Mexico station of Columbia Scientific Balloon Facility (CSBF) on September 18, 2019. BITSE obtained 17,060 coronal images at a float altitude of $\approx \mbox{128,000}$ ≈ 128,000 feet ($\approx 39$ ≈ 39  km) over a period of $\approx 4$ ≈ 4  hrs. BITSE flight software was based on NASA’s core Flight System, which was designed to help develop flight quality software. We used EVTM (Ethernet Via Telemetry) to download science data during operations; all images were stored on board using flash storage. At the end of the mission, all data were recovered and analyzed. Preliminary analysis shows that BITSE imaged the solar minimum corona with the equatorial streamers on the east and west limbs. The narrow streamers observed by BITSE are in good agreement with the geometric properties obtained by the Solar and Heliospheric Observatory (SOHO) coronagraphs in the overlapping physical domain. In spite of the small signal-to-noise ratio ($\approx 14$ ≈ 14 ) we were able to obtain the temperature and flow speed of the western steamer. In the heliocentric distance range 4 – 7 Rs on the western streamer, we obtained a temperature of $\approx 1.0\pm 0.3$ ≈ 1.0 ± 0.3  MK and a flow speed of $\approx 260$ ≈ 260  km s−1 with a large uncertainty interval.

scholarly journals 3D phonon microscopy with sub-micron axial-resolution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Richard J. Smith ◽  
Fernando Pérez-Cota ◽  
Leonel Marques ◽  
Matt Clark
Keyword(s):  
Signal To Noise Ratio ◽  
Single Cells ◽  
Optical Resolution ◽  
Acquisition Time ◽  
Label Free ◽  
Axial Resolution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Accuracy And Precision ◽  
Good Agreement

AbstractBrillouin light scattering (BLS) is an emerging method for cell imaging and characterisation. It allows elasticity-related contrast, optical resolution and label-free operation. Phonon microscopy detects BLS from laser generated coherent phonon fields to offer an attractive route for imaging since, at GHz frequencies, the phonon wavelength is sub-optical. Using phonon fields to image single cells is challenging as the signal to noise ratio and acquisition time are often poor. However, recent advances in the instrumentation have enabled imaging of fixed and living cells. This work presents the first experimental characterisation of phonon-based axial resolution provided by the response to a sharp edge. The obtained axial resolution is up to 10 times higher than that of the optical system used to take the measurements. Validation of the results are obtained with various polymer objects, which are in good agreement with those obtained using atomic force microscopy. Edge localisation, and hence profilometry, of a phantom boundary is measured with accuracy and precision of approximately 60 nm and 100 nm respectively. Finally, 3D imaging of fixed cells in culture medium is demonstrated.

Physical AWGN Channel Emulator for Bit Error Rate Test of Digital Baseband Communication

2012 ◽  
Vol 241-244 ◽  
pp. 2491-2495 ◽  
Author(s):  
Antonio Boscolo ◽  
Francesca Vatta ◽  
Francesco Armani ◽  
Emanuele Viviani ◽  
Daniele Salvalaggio
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Signal To Noise Ratio ◽  
Error Correcting Codes ◽  
Noise Sources ◽  
Channel Emulator ◽  
Physical Channel ◽  
Rate Test ◽  
Data Signal ◽  
Good Agreement

This paper presents a physical channel emulator solution for applications such as Bit Error Rate Testing of Error Correcting Codes. The solution relies on an analog White Gaussian Noise Generator coupled additively with an analog data signal to emulate the communication channel. This is interfaced to a computer through a USB connection, allowing the use of programs in different environments, such as Matlab and Labview. This solution can allow different types of channels to be emulated and with different noise sources. A software-based method to measure Signal to Noise Ratio and to characterize the channel is also presented. The system has been validated using a Matlab interface implementing multiple error correcting codes and showed good agreement with the theoretical model.

scholarly journals A-PHOT: a new, versatile code for precision aperture photometry

2019 ◽  
Vol 622 ◽  
pp. A169 ◽  
Author(s):  
E. Merlin ◽  
S. Pilo ◽  
A. Fontana ◽  
M. Castellano ◽  
D. Paris ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Input Parameter ◽  
Repeated Measurements ◽  
Versatile Tool ◽  
Local Background ◽  
Resolution Imaging ◽  
Astronomical Images ◽  
Extragalactic Surveys ◽  
Photometric Measurements ◽  
Good Agreement

Aims. We present A-PHOT, a new publicly available code for performing aperture photometry on astronomical images, that is particularly well suited for multi-band extragalactic surveys. Methods.A-PHOT estimates the fluxes emitted by astronomical objects within a chosen set of circular or elliptical apertures. Unlike other widely used codes, it runs on predefined lists of detected sources, allowing for repeated measurements on the same list of objects on different images. This can be very useful when forced photometric measurement on a given position is needed. A-PHOT can also estimate morphological parameters and a local background flux, and compute on-the-fly individual optimized elliptical apertures, in which the signal-to-noise ratio is maximized. Results. We check the performance of A-PHOT on both synthetic and real test datasets: we explore a simulated case of a space-based high-resolution imaging dataset, investigating the input parameter space to optimize the accuracy of the performance, and we exploit the CANDELS GOODS-South data to compare the A-PHOT measurements with those from the survey legacy catalogs, finding good agreement overall. Conclusions.A-PHOT proves to a useful and versatile tool for quickly extracting robust and accurate photometric measurements and basic morphological information of galaxies and stars, with the advantage of allowing for various measurements of fluxes at any chosen position without the need of a full detection run, and for determining the basic morphological features of the sources.

Application of Taguchi method in the optimization of geometric parameters for double pin joint configurations made from glass–epoxy nanoclay laminates

2016 ◽  
Vol 51 (19) ◽  
pp. 2689-2706 ◽  
Author(s):  
Manjeet Singh ◽  
J S Saini ◽  
H Bhunia ◽  
Paramdeep Singh
Keyword(s):  
Taguchi Method ◽  
Signal To Noise Ratio ◽  
Characteristic Curve ◽  
Free Edge ◽  
Geometric Parameters ◽  
Signal To Noise ◽  
Bearing Strength ◽  
Significant Parameter ◽  
Numerical Predictions ◽  
Good Agreement

In the present work, Taguchi method was used for the optimization of geometric parameters for double pin joint configurations. The orthogonal array, the signal-to-noise ratio, and analysis of variance were employed to study the effect of geometric parameters on the bearing strength of the joints. Geometric parameters, i.e. the distance from the free edge of the specimen to the diameter of the first hole (E/D) ratio, width of the specimen to the diameter of the hole (W/D) ratio, the distance between the two holes to the diameter of the hole (P/D) ratio and side width to the diameter of the hole (K/D) ratio were investigated for the serial and parallel hole configurations. The results demonstrate that the E/D ratio is the most significant parameter to increase the bearing strength in both serial and parallel pin joint configurations. Its percentage contribution is about 84.5% and 64.23% in serial and parallel pin joint configurations, respectively. Characteristic curve with Tsai–Wu failure criterion was used for the prediction of the bearing strength in the joints numerically. A good agreement was obtained between experimental results and numerical predictions.

scholarly journals Snow Depth Estimation on Slopes Using GPS-Interferometric Reflectometry

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4994
Author(s):  
Haohan Wei ◽  
Xiufeng He ◽  
Yanming Feng ◽  
Shuanggen Jin ◽  
Fei Shen
Keyword(s):  
Time Series ◽  
Snow Depth ◽  
Water Cycle ◽  
Signal To Noise Ratio ◽  
Plate Boundary ◽  
Depth Estimation ◽  
Tilted Surface ◽  
Global Water Cycle ◽  
Gps Antenna ◽  
Good Agreement

Snow is one of the most critical sources of freshwater, which influences the global water cycle and climate change. However, it is difficult to monitor global snow variations with high spatial–temporal resolution using traditional techniques due to their costly and labor-intensive nature. Nowadays, the Global Positioning System Interferometric Reflectometry (GPS-IR) technique can measure the average snow depth around a GPS antenna using its signal-to-noise ratio (SNR) data. Previous studies focused on the use of GPS data at sites located in flat areas or on very gentle slopes. In this contribution, we propose a strategy called the Tilted Surface Strategy (TSS), which uses the SNR data reflected only from the flat quadrants to estimate the snow depth instead of the conventional strategy, which employs all the SNR data reflected from the whole area around a GPS antenna. Three geodetic GPS sites from the Plate Boundary Observatory (PBO) project were chosen in this experimental study, of which GPS sites p683 and p101 were located on slopes with their gradients up to 18% and the site p025 was located on a flat area. Comparing the snow depths derived with the GPS-IR TSS method with the snow depth results provided with the GPS-PBO, i.e., GPS-IR with the conventional strategy, the Snowpack Telemetry (SNOTEL) network measurements and gridded Snow Data Assimilation System (SNODAS) estimates, it was found that the snow depths derived with the four methods had a good agreement, but the snow depth time series with the GPS-IR TSS method were closer to the SNOTEL measurements and the SNODAS estimates than those with GPS-PBO method. Similar observations were also obtained from the cumulative snowfall time series. Results generally indicated that for those GPS sites located on slopes, the TSS strategy works better.

Single drop square wave polarography

1981 ◽  
Vol 59 (24) ◽  
pp. 3326-3333 ◽  
Author(s):  
Louis Ramaley ◽  
Wee Tee Tan
Keyword(s):  
Square Wave Voltammetry ◽  
Signal To Noise Ratio ◽  
Single Drop ◽  
Plane Model ◽  
Square Wave ◽  
Electrode Reactions ◽  
Wave Voltammetry ◽  
Average Current ◽  
The Times ◽  
Good Agreement

The theory of square wave voltammetry for reversible electrode reactions is expanded to include average currents and currents flowing to a growing drop (single drop square wave polarography) using an expanding plane model. Excellent agreement between theory and experiment was found for the reduction of Fe(III), good agreement for the reduction of Cd(II). The expanding plane model proved superior, but not greatly superior to the simpler theory. For the case of average current the effect on the polarogram of the times at which integration is started and stopped is discussed. Integration decreases sensitivity but increases signal-to-noise ratio. The conditions for maximum analytical usefulness are presented.

scholarly journals Overview of MPLNET Version 3 Cloud Detection

2016 ◽  
Vol 33 (10) ◽  
pp. 2113-2134 ◽  
Author(s):  
Jasper R. Lewis ◽  
James R. Campbell ◽  
Ellsworth J. Welton ◽  
Sebastian A. Stewart ◽  
Phillip C. Haftings
Keyword(s):  
Optical Depth ◽  
Space Flight ◽  
Signal To Noise Ratio ◽  
Cloud Detection ◽  
Signal To Noise ◽  
Cloud Optical Depth ◽  
Goddard Space ◽  
Goddard Space Flight Center ◽  
Noise Ratio ◽  
Micro Pulse Lidar

AbstractThe National Aeronautics and Space Administration Micro Pulse Lidar Network, version 3, cloud detection algorithm is described and differences relative to the previous version are highlighted. Clouds are identified from normalized level 1 signal profiles using two complementary methods. The first method considers vertical signal derivatives for detecting low-level clouds. The second method, which detects high-level clouds like cirrus, is based on signal uncertainties necessitated by the relatively low signal-to-noise ratio exhibited in the upper troposphere by eye-safe network instruments, especially during daytime. Furthermore, a multitemporal averaging scheme is used to improve cloud detection under conditions of a weak signal-to-noise ratio. Diurnal and seasonal cycles of cloud occurrence frequency based on one year of measurements at the Goddard Space Flight Center (Greenbelt, Maryland) site are compared for the new and previous versions. The largest differences, and perceived improvement, in detection occurs for high clouds (above 5 km, above MSL), which increase in occurrence by over 5%. There is also an increase in the detection of multilayered cloud profiles from 9% to 19%. Macrophysical properties and estimates of cloud optical depth are presented for a transparent cirrus dataset. However, the limit to which the cirrus cloud optical depth could be reliably estimated occurs between 0.5 and 0.8. A comparison using collocated CALIPSO measurements at the Goddard Space Flight Center and Singapore Micro Pulse Lidar Network (MPLNET) sites indicates improvements in cloud occurrence frequencies and layer heights.

scholarly journals Greenland Ice Mapping Project: ice flow velocity variation at sub-monthly to decadal timescales

2018 ◽  
Vol 12 (7) ◽  
pp. 2211-2227 ◽  
Author(s):  
Ian Joughin ◽  
Ben E. Smith ◽  
Ian Howat
Keyword(s):  
Flow Speed ◽  
Velocity Variation ◽  
Landsat 8 ◽  
North West ◽  
South West ◽  
Speed Up ◽  
Ice Velocity ◽  
Year 2000 ◽  
The Impact ◽  
Good Agreement

Abstract. We describe several new ice velocity maps produced by the Greenland Ice Mapping Project (GIMP) using Landsat 8 and Copernicus Sentinel 1A/B data. We then focus on several sites where we analyse these data in conjunction with earlier data from this project, which extend back to the year 2000. At Jakobshavn Isbræ and Køge Bugt, we find good agreement when comparing results from different sensors. In a change from recent behaviour, Jakobshavn Isbræ began slowing substantially in 2017, with a midsummer peak that was even slower than some previous winter minima. Over the last decade, we identify two major slowdown events at Køge Bugt that coincide with short-term advances of the terminus. We also examined populations of glaciers in north-west and south-west Greenland to produce a record of speed-up since 2000. Collectively these glaciers continue to speed up, but there are regional differences in the timing of periods of peak speed-up. In addition, we computed trends in winter flow speed for much of the south-west margin of the ice sheet and find little in the way of statistically significant changes over the period covered by our data. Finally, although the consistency of the data is generally good over time and across sensors, our analysis indicates that substantial differences can arise in regions with high strain rates (e.g. shear margins) where sensor resolution can become a factor. For applications such as constraining model inversions, users should factor in the impact that the data's resolution has on their results.

Cognitive Multi-Relay Transmission over Asymmetric Fading Channels with Imperfect CSI

2017 ◽  
Vol 3 (1) ◽  
pp. 46
Author(s):  
Nguyen Hong Giang ◽  
Vo Nguyen Quoc Bao ◽  
Hung Nguyen-Le
Keyword(s):  
Fading Channels ◽  
Rayleigh Fading ◽  
Signal To Noise Ratio ◽  
Rician Fading ◽  
Channel State ◽  
Relay System ◽  
Relay Systems ◽  
Secondary Network ◽  
Secondary Networks ◽  
Good Agreement

Outage performance of a cognitive multi-relay system using imperfect channel state information (CSI) of interfering links is formulated in this paper. In the considered cognitive system, it is assumed that wireless channels in the secondary network (source-to-relay and relay-to-destination links) experience Rician fading whereas interfering channels between primary and secondary networks undergo Rayleigh fading. Under the assumption of asymmetric fading, an outage probability (OP) expression of the secondary network is approximately formulated. Analytical OP values are in good agreement with related empirical ones in low signal-to-noise ratio (SNR) regimes. As a result, the approximate OP expression can be used to quantify the effect of asymmetric fading channels and CSI imperfection on the performance of cognitive multi-relay systems in practical SNR ranges.

scholarly journals Assessment of ice flow dynamics in the zone close to the calving front of Antarctic ice shelves

2015 ◽  
Vol 61 (230) ◽  
pp. 1194-1206 ◽  
Author(s):  
Martin G. Wearing ◽  
Richard C.A. Hindmarsh ◽  
M. Grae Worster
Keyword(s):  
Flow Speed ◽  
Flow Dynamics ◽  
Rheological Parameters ◽  
Ice Thickness ◽  
Scaling Analysis ◽  
Ice Shelf ◽  
Ice Flow ◽  
Ice Shelves ◽  
The Relationship ◽  
Good Agreement

AbstractWe investigate the relationship between four ice-shelf characteristics in the area close to the calving front: ice flow speed, strain rate, ice thickness and shelf width. Data are compiled for these glaciological parameters at the calving fronts of 22 Antarctic ice shelves. Clarification concerning the viscous supply of ice to the calving front is sought following the empirical calving law of Alley and others (2008), derived from a similar but smaller dataset, and the scaling analysis of Hindmarsh (2012). The dataset is analysed and good agreement is observed between the expected theoretical scaling and geophysical data for the flow of ice near the calving front in the case of ice shelves that are laterally confined and have uniform rheology. The lateral confinement ensures flow is aligned in the along-shelf direction, and uniform rheological parameters mean resistance to flow is provided by near-stationary ice in the grounded margins. In other cases, the velocity is greater than predicted, which we attribute to marginal weakening or the presence of ice tongues.

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