scholarly journals Analysis of Dark Current in BRITE Nanostellite CCD Sensors

2018 ◽  
Author(s):  
Adam Popowicz
Keyword(s):  
Image Processing ◽  
Dark Current ◽  
Temporal Evolution ◽  
Energetic Particles ◽  
Linear Increase ◽  
Current Data ◽  
Thermal Activity ◽  
Silicon Lattice ◽  
Empirical Rule ◽  
Photometric Observations

The BRightest Target Explorer (BRITE) is the pioneering nanosatellite mission dedicated for photometric observations of the brightest stars in the sky. The BRITE CCD sensors are poorly shielded against extensive flux of energetic particles which constantly induce defects in the silicon lattice. In this paper we investigate the temporal evolution of the generation of the dark current in the BRITE CCDs over almost 4 years after launch. Utilizing several steps of image processing and employing normalization of the results it was possible to obtain useful information about the progress of thermal activity in the sensors. The outcomes show clear and consistent linear increase of induced damage despite the fact that only about 0.14% of CCD pixels were probed. By performing the analysis of temperature dependencies of the dark current, we identified the observed defects as phosphorus-vacancy (PV) pairs, which are common in proton irradiated CCD matrices. Moreover, the Meyer-Neldel empirical rule was confirmed in our dark current data, yielding EMN=24.8 meV for proton-induced PV defects.

scholarly journals Properties of the inner penumbral boundary and temporal evolution of a decaying sunspot

2018 ◽  
Vol 620 ◽  
pp. A191 ◽  
Author(s):  
M. Benko ◽  
S. J. González Manrique ◽  
H. Balthasar ◽  
P. Gömöry ◽  
C. Kuckein ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Temporal Evolution ◽  
Vertical Component ◽  
Field Vector ◽  
Linear Increase ◽  
Vertical Magnetic Field ◽  
Magnetic Diffusion ◽  
The Magnetic Field ◽  
Linear Decay

Context. It has been empirically determined that the umbra-penumbra boundaries of stable sunspots are characterized by a constant value of the vertical magnetic field. Aims. We analyzed the evolution of the photospheric magnetic field properties of a decaying sunspot belonging to NOAA 11277 between August 28–September 3, 2011. The observations were acquired with the spectropolarimeter on-board of the Hinode satellite. We aim to prove the validity of the constant vertical magnetic-field boundary between the umbra and penumbra in decaying sunspots. Methods. A spectral-line inversion technique was used to infer the magnetic field vector from the full-Stokes profiles. In total, eight maps were inverted and the variation of the magnetic properties in time were quantified using linear or quadratic fits. Results. We find a linear decay of the umbral vertical magnetic field, magnetic flux, and area. The penumbra showed a linear increase of the vertical magnetic field and a sharp decay of the magnetic flux. In addition, the penumbral area quadratically decayed. The vertical component of the magnetic field is weaker on the umbra-penumbra boundary of the studied decaying sunspot compared to stable sunspots. Its value seem to be steadily decreasing during the decay phase. Moreover, at any time of the sunspot decay shown, the inner penumbra boundary does not match with a constant value of the vertical magnetic field, contrary to what is seen in stable sunspots. Conclusions. During the decaying phase of the studied sunspot, the umbra does not have a sufficiently strong vertical component of the magnetic field and is thus unstable and prone to be disintegrated by convection or magnetic diffusion. No constant value of the vertical magnetic field is found for the inner penumbral boundary.

AlGaN p-i-n Photodiode Arrays for Solar-Blind Applications

2000 ◽  
Vol 639 ◽  
Author(s):  
P. Lamarre ◽  
A. Hairston ◽  
S. Tobin ◽  
K. K. Wong ◽  
M. F. Taylor ◽  
...  
Keyword(s):  
Bias Voltage ◽  
Dark Current ◽  
Current Data ◽  
Conduction Model ◽  
Zero Bias ◽  
Imaging Results ◽  
Solar Blind ◽  
Uv Response ◽  
Full Depletion ◽  
Back Illuminated

ABSTRACTThis paper presents UV imaging results for a 256×256 AlGaN Focal Plane Array that uses a back-illuminated AlGaN heterostructure p-i-n photodiode array, with 30×30 μm2 unit cells, operating at zero bias voltage, with a narrow-band UV response between 310 and 325 nm. The 256×256 array was fabricated from a multilayer AlGaN film grown by MOCVD on a sapphire substrate. The UV response operability (>0.4×average) was 94.8%, and the UV response uniformity (σ/μ) was 16.8%. Data are also presented for back-illuminated AlGaN p-i-n photodiodes from other films with cutoff wavelengths ranging between 301 and 364 nm. Data for variable-area diagnostic arrays of p-i-n AlGaN photodiodes with a GaN absorber (cutoff=364 nm) show: (1) high external quantum efficiency (50% at V=0 and 62% at V=-9 V); (2) the dark current is proportional to junction area, not perimeter; (3) the forward and reverse currents are uniform (σ/μ=50% for forty 30×30 μm2 diodes at V=−40 V); (4) the reverse-bias dark current data versus temperature and bias voltage can be fit very well by a hopping conduction model; and (5) capacitance versus voltage data are consistent with nearly full depletion of the unintentionally-doped 0.4 μm thick GaN absorber layer and imply a donor concentration of 3-4×1016 cm−3.

Analysis of Spatial–Temporal Evolution of Mining-Induced Fracture Field: A Case Study Using Image Processing in the Shaqu Coal Mine, China

2019 ◽  
Vol 29 (3) ◽  
pp. 1601-1615 ◽  
Author(s):  
Zhiheng Cheng ◽  
Biao Liu ◽  
Quanle Zou ◽  
Xin Wang ◽  
Jicheng Feng ◽  
...  
Keyword(s):  
Image Processing ◽  
Coal Mine ◽  
Temporal Evolution

Analysis of Black Level Calibration Algorithm for CIS

2014 ◽  
Vol 599-601 ◽  
pp. 1397-1402
Author(s):  
Hong Tao Yao ◽  
Zi Qiang Wang ◽  
Yuan Bao Gu ◽  
Zhen Gang Jiang
Keyword(s):  
Image Processing ◽  
Dark Current ◽  
Image Sensors ◽  
Improve Quality ◽  
Operational Principle ◽  
Cmos Image Sensors ◽  
Calibration Algorithm ◽  
Black Level

This paper presents the structure and the operational principle of CMOS image sensors. And then the reason is illuminated for producing dark current and black level of CMOS image sensors. It is necessary to calibrate dark current and black level to improve quality of CMOS image sensors. The dark current is corrected by optimizing pixel structure, perfecting technology, improving 6layout, and correction double sample. But these ways do not calibrate black level. So, it is important to calibrate black level using black level calibration algorithm in the stage of image processing.

scholarly journals Forget Pixels: Adaptive Particle Representation of Fluorescence Microscopy Images

2018 ◽  
Author(s):  
Bevan L. Cheeseman ◽  
Ulrik Günther ◽  
Mateusz Susik ◽  
Krzysztof Gonciarz ◽  
Ivo F. Sbalzarini
Keyword(s):  
Image Processing ◽  
Fluorescence Microscopy ◽  
Data Compression ◽  
Image Data ◽  
Current Data ◽  
3D Image ◽  
Regular Grid ◽  
Adaptive Representation ◽  
Microscopy Images ◽  
Content Aware

AbstractModern microscopy modalities create a data deluge with gigabytes of data generated each second, and terabytes per day. Storing and processing these data is a severe bottleneck, not fully alleviated by data compression. We argue that this is because images are processed as regular grids of pixels. To address the root of the problem, we here propose a content-adaptive representation of fluorescence microscopy images called the Adaptive Particle Representation (APR). The APR replaces the regular grid of pixels with particles positioned according to image content. This overcomes storage bottlenecks, as data compression does, but additionally overcomes memory and processing bottlenecks, since the APR can directly be used in processing without going back to pixels. We present the ideas, concepts, and algorithms of the APR and validate them using noisy 3D image data. We show that the APR represents the content of an image while maintaining image quality. We then show that the adaptivity of the APR provides orders of magnitude benefits across a range of image processing tasks. Therefore, the APR provides a simple, extendable, and efficient content-aware representation of images that relaxes current data and processing bottlenecks.

scholarly journals STUDY OF THE TEMPORAL EVOLUTION OF WHITENING IN TEETH UNDERGOING MOUTHWASHES USING DIGITAL IMAGE PROCESSING

2016 ◽  
Vol 28 (1) ◽  
pp. 9-13
Author(s):  
Leonardo Díaz ◽  
Yaileth Morales ◽  
Cesar Torres
Keyword(s):  
Image Processing ◽  
Hydrogen Peroxide ◽  
Digital Image Processing ◽  
Digital Image ◽  
Temporal Evolution ◽  
Personal Satisfaction ◽  
Human Teeth ◽  
Tooth Color ◽  
Dental Imaging ◽  
Esthetic Dentistry

Currently, many patients are interested in esthetic dentistry treatments for various reasons: from the search for personal satisfaction, up to needs labor type. The esthetic dentistry reference in our society is determined by several factors, including one that produces more dissatisfaction is abnormal tooth color or that does not meet the patient's expectations. For this reason it has been designed and implemented an algorithm in MATLAB that captures, digitizes, pre-processing and analyze dental imaging by allowing to evaluate the degree of bleaching caused by the use of mouthwash. The samples analyzed were human teeth extracted, which were subjected to different concentrations of mouthwash of several brands or manufacturers that offer teeth whitening when using these products, different concentrations of hydrogen peroxide were also used because this is the component prin- cipal in whitening products.

scholarly journals Probing the solar origin of energy build-up and release in solar energetic particles

2012 ◽  
Vol 8 (S294) ◽  
pp. 539-540
Author(s):  
Arun Kumar Awasthi ◽  
Rajmal Jain ◽  
Nipa J. Bhatt
Keyword(s):  
Magnetic Field ◽  
Temporal Evolution ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Spatial Evolution ◽  
X Ray ◽  
Solar Origin ◽  
Multi Wavelength ◽  
Temporal And Spatial ◽  
The Magnetic Field

AbstractWe study the temporal and spatial evolution of magnetic field parameters, and multi-wavelength observations of the AR 11226 and AR 11261, observed during 02-09 June 2011 and 31 July to 06 August 2011 respectively, to probe the origin of the associated solar energetic particles (SEPs). The magnetic-field toplogy of both ARs shows complex magnetic structure of β and βγ configuration. The X-ray observations by GOES and RHESSI reveal that the AR 11226 as well as AR 11261 has been most turbulent to produce flares accompanying CMEs and SEPs. We restrict our study of magnetic field evolution of ARs to helio-longitudes E20-W70. The AR 11226 produced 28 flares (⩾ GOES C-class) and 8 CMEs as well as 5 SEPs. On the other hand, the AR 11261 produced 29 flares (⩾ GOES C class), 8 CMEs as well as 5 SEPs. We study the temporal evolution of magnetic field parameters viz. gradient, shear, rotation to probe the origin of the energy release in the flare and associated CME and SEP. We do not find convincing relationship in view of predicting SEPs.

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

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