2,774 research outputs found
Active cavity radiometer, type III - An automatic, absolute standard, highly accurate detector
Instrument of simple construction operates without vacuum enclosure over wide pressure range and temperatures from 218 to 398 deg K and defines absolute radiometric scale to within less than 0.5 mW/sq cm. It has potential application to meteorology and climatology and operates on electrical substitution calorimeter principle
Active Cavity Radiometer (ACR)
The objective of the Active Cavity Radiometer (ACR) experiment on the Atmospheric Laboratory for Applications and Science (ATLAS) mission is the measurement of the total solar irradiance with state-of-the-art accuracy and precision. This experiment is part of an ongoing program of space flight observations to study short- and long-term variations in the total solar output of optical energy. Precise observations of solar total irradiance provide information on the solar cycle and other long-term trends in solar output that are of climatological significance as well as short-term solar physics phenomena such as radiation anisotropy, active region structure, missing flux due to sunsports, bolometry of solar flares, global oscillations, coronal holes, and large-scale convective flows. The principal role of the ATLAS ACR observations will be in support of extended solar irradiance experiments on free-flying satellites. Annual in-flight comparison of observations by both ATLAS and free-flying experiments is an important part of sustaining the long-term precision of the climatological solar irradiance data base at the required + or - 0.1 percent level. Another role for ATLAS solar irradiance measurements will be establishment of the radiation scale at the solar total flux level in the International System of Units (SI). Two types of pyrheliometers, the ACR and SOLCON, will be directly intercompared during the ATLAS 1 mission. Addition of other sensors is planned for future reflights. Comparisons of solar observations by different pyrheliometers in the shuttle space environment will provide the most definitive experiment for determining their accuracy in defining the radiation scale at the solar total flux level
ACRIM total solar irradiance satellite composite validation versus TSI proxy models
The satellite total solar irradiance (TSI) database provides a valuable
record for investigating models of solar variation used to interpret climate
changes. The 35-year ACRIM TSI satellite composite was updated using
corrections to ACRIMSAT/ACRIM3 results derived from recent testing at the
Laboratory for Atmospheric and Space Physics/Total solar irradiance Radiometer
Facility (LASP/TRF). The corrections lower the ACRIM3 scale by ~5000 ppm, in
close agreement with the scale of SORCE/TIM results (solar constant ~1361
W/m^2). Relative variations and trends are not changed. Differences between the
ACRIM and PMOD TSI composites, e.g. the decadal trending during solar cycles
21-22, are tested against a set of solar proxy models, including analysis of
Nimbus7/ERB and ERBS/ERBE results available to bridge the ACRIM Gap
(1989-1992). Our findings confirm: (1) The validity of the TSI peak in the
originally published ERB results in early 1979 during solar cycle 21; (2) The
correctness of originally published ACRIM1 results during the SMM spin mode
(1981-1984); (3) The upward trend of originally published ERB results during
the ACRIM Gap; (4) The occurrence of a significant upward TSI trend between the
minima of solar cycles 21 and 22 and (5) a decreasing trend during solar cycles
22-23. Our findings do not support: (1) The downward corrections to originally
published ERB and ACRIM1 results during solar cycle 21; (2) A step function
sensitivity change in ERB results at the end-of-September 1989; (3) the
validity of ERBE's downward trend during the ACRIM Gap or (4) the use of ERBE
results to bridge the ACRIM Gap. Our analysis provides a first order validation
of the ACRIM TSI composite approach and its 0.037%/decade upward trend during
solar cycles 21-22. Thus, solar forcing of climate change may be a
significantly larger factor than represented in the CMIP5 general circulation
climate models.Comment: 26 pages, 15 figure
Planetary harmonics in the historical Hungarian aurora record (1523-1960)
The historical Hungarian auroral record extends from 1523 to 1960 and is
longer than the sunspot record. Harmonic analysis reveals four major
multidecadal secular cycles forming an approximate harmonic set at periods of
42.85, 57.13, 85.7 and 171.4 years. These four frequencies are very close to
the four major heliospheric oscillations relative to the center of mass of the
solar system caused by Jupiter, Saturn, Uranus and Neptune. Similar frequencies
are found in solar radiation models based on long cosmogenic isotope records
(Steinhilber et al. 2012) and in long records of naked-eye sunspot observations
(Vaquero et al., 2002). Harmonic regression models are used to reconstruct and
forecast aurora and solar activity for the period 1956-2050. The model
predicts: (1) the multidecadal solar minimum in the 1970s that is also observed
in the sunspot record; (2) a solar maximum in 2000-2002 that is observed in the
ACRIM total solar irradiance satellite composite; (3) a prolonged solar minimum
centered in the 2030s. These findings support a hypothesis that the Sun, the
heliosphere and the terrestrial magnetosphere are partially modulated by
planetary gravitational and magnetic forces synchronized to planetary
oscillations, as also found in other recent publications (Scafetta, 2010,
2012a, 2012c, 2012d; Abreu et al., 2012; Tan & Cheng, 2012).Comment: 29 pages, 6 figures, 2 table
Multi-scale comparative spectral analysis of satellite total solar irradiance measurements from 2003 to 2013 reveals a planetary modulation of solar activity and its non-linear dependence on the 11-year solar cycle
Herein we adopt a multi-scale dynamical spectral analysis technique to
compare and study the dynamical evolution of the harmonic components of the
overlapping ACRIMSAT/ACRIM3, SOHO/VIRGO and SORCE/TIM total solar irradiance
(TSI) records during 2003.15 to 2013.16 in solar cycles 23 and 24. The three
TSI time series present highly correlated patterns. Significant power spectral
peaks are common to these records and are observed at the following periods:
0.070 year, 0.097 year, 0.20 year, 0.25 year, 0.30-0.34 year, 0.39 year. Less
certain spectral peaks occur at about 0.55 year, 0.60-0.65 year and 0.7-0.9
year. Four main frequency periods at 24.8 days (0.068 year), 27.3 days (0.075
year), at 34-35 days (0.093-0.096 year) and 36-38 days (0.099-0.104 year)
characterize the solar rotation cycle. The amplitude of these oscillations, in
particular of those with periods larger than 0.5 year, appears to be modulated
by the 11-year solar cycle. Similar harmonics have been found in other solar
indices. The observed periodicities are found highly coherent with the spring,
orbital and synodic periods of Mercury, Venus, Earth and Jupiter. We conclude
that solar activity is likely modulated by planetary gravitational and
electromagnetic forces acting on the sun. The strength of the sun's response to
planetary forcing depends non-linearly on the state of internal solar dynamics:
planetary-sun coupling effects are enhanced during solar activity maxima and
attenuated during minima.Comment: 18 pages, 10 figures, 3 table
Development of nonflammable coating for polycarbonate Final report
Sodium and potassium silicates applied to polycarbonates to provide nonflammable coating
Polymer Dissolution Model: An Energy Adaptation Of The Critical Ionization Theory
The current scale of features size in the microelectronics industry has reached the point where molecular level interactions affect process fidelity and produce excursions from the continuum world like line edge roughness (LER). Here we present a 3D molecular level model based on the adaptation of the critical ionization (CI) theory using a fundamental interaction energy approach. The model asserts that it is the favorable interaction between the ionized part of the polymer and the developer solution which renders the polymer soluble. Dynamic Monte Carlo methods were used in the current model to study the polymer dissolution phenomenon. The surface ionization was captured by employing an electric double layer at the interface, and polymer motion was simulated using the Metropolis algorithm. The approximated interaction parameters, for different species in the system, were obtained experimentally and used to calibrate the simulated dissolution rate response to polymer molecular weight and developer concentration. The predicted response is in good agreement with experimental dissolution rate data. The simulation results support the premise of the CI theory and provide an insight into the CI model from a new prospective. This model may provide a means to study the contribution of development to LER and other related defects based on molecular level interactions between distinct components in the polymer and the developer.Chemical Engineerin
Comparison of Decadal Trends among Total Solar Irradiance Composites of Satellite Observations
We present a new analysis of the two-decade-old controversy over interpretation of satellite observations of total solar irradiance (TSI) since 1978 and the implications of our findings for TSI as a driver of climate change. Our approach compares the methods of constructing the two most commonly referenced TSI composites (ACRIM and PMOD) that relate successive observational databases and two others recently constructed using a novel statistical approach. Our primary focus is on the disparate decadal trending results of the ACRIM and PMOD TSI composite time series, namely, whether they indicate an increasing trend from 1980 to 2000 and a decreasing trend thereafter (ACRIM) or a continuously decreasing trend since 1980 (PMOD). Construction of the four-decade observational TSI composites from 1978 to the present requires the use of results from two less precise Earth Radiation Budget experiments (Nimbus7/ERB and ERBS/ERBE) during the so-called ACRIM-Gap (1989.5–1991.8), between the end of the ACRIM1 and the beginning of the ACRIM2 experiments. The ACRIM and PMOD composites used the ERB and ERBE results, respectively, to bridge the gap. The well-established paradigm of positive correlation between Solar Magnetic Field Strength (SMFS) and TSI supports the validity of the upward trend in the ERB results and the corresponding decadal upward trend of the ACRIM composite during solar cycles 21 and 22. The ERBE results have a sensor degradation caused downward gap trend, contrary to the SMFS/TSI paradigm, that biased the PMOD composite decadal trend downward during solar cycles 21 and 22. The different choice of gap bridging data is clearly the cause of the ACRIM and PMOD TSI trending difference, agreeing closely in both magnitude and direction. We also analyze two recently proposed statistical TSI composites. Unfortunately their methodology cannot account for the gap degradation of the ERBE experiment and their resulting uncertainties are too large to uniquely distinguish between the trending of the ACRIM and PMOD composites. Our analysis supports the ACRIM TSI increasing trend during the 1980 to 2000 period, followed by a long-term decreasing trend since
Nonthermal hard X-ray excess in the Coma cluster: resolving the discrepancy between the results of different PDS data analyses
The detection of a nonthermal excess in the Coma cluster spectrum by two
BeppoSAX observations analyzed with the XAS package (Fusco-Femiano et al.) has
been disavowed by an analysis (Rossetti & Molendi) performed with a different
software package (SAXDAS) for the extraction of the spectrum. To resolve this
discrepancy we reanalyze the PDS data considering the same software used by
Rossetti & Molendi. A correct selection of the data and the exclusion of
contaminating sources in the background determination show that also the SAXDAS
analysis reports a nonthermal excess with respect to the thermal emission at
about the same confidence level of that obtained with the XAS package
(~4.8sigma). Besides, we report the lack of the systematic errors investigated
by Rossetti & Molendi and Nevalainen et al. taking into account the whole
sample of the PDS observations off the Galactic plane, as already shown in our
data analysis of Abell 2256 (Fusco-Femiano, Landi & Orlandini). All this
eliminates any ambiguity and confirms the presence of a hard tail in the
spectrum of the Coma cluster.Comment: 12 pages, 2 figures. Accepted for publication in ApJ Letter
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Compositions for dark-field polymerization and method of using the same for imprint lithography processes
A composition is provided and a method of using the same to form a pattern on a substrate using imprint lithography employing dark-field polymerization is disclosed. The composition includes a polymerizable bisvinylether and an initiator that produces an acid in response to radiation.Board of Regents, University of Texas Syste
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