A New Revision of the Solar Irradiance Climate Data Record Incorporates Recent Research into Proxies of Sunspot Darkening and the Sunspot Number Record

Science.gov (United States)

Coddington, O.; Lean, J.; Pilewskie, P.; Baranyi, T.; Snow, M. A.; Kopp, G.; Richard, E. C.; Lindholm, C.

2017-12-01

An operational climate data record (CDR) of total and spectral solar irradiance became available in November 2015 as part of the National Oceanographic and Atmospheric Administration's National Centers for Environmental Information Climate Data Record Program. The data record, which is updated quarterly, is available from 1610 to the present as yearly-average values and from 1882 to the present as monthly- and daily-averages, with associated time and wavelength-dependent uncertainties. It was developed jointly by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics and the Naval Research Laboratory, and, together with the source code and supporting documentation, is available at https://www.ncdc.noaa.gov/cdr/. In the Solar Irradiance CDR, total solar irradiance (TSI) and solar spectral irradiance (SSI) are estimated from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk. The models are constructed using linear regression of proxies of solar sunspot and facular features with the approximately decade-long irradiance observations from the SOlar Radiation and Climate Experiment. A new revision of this data record was recently released in an ongoing effort to reduce solar irradiance uncertainties in two ways. First, the sunspot darkening proxy was revised using a new cross calibration of the current sunspot region observations made by the Solar Observing Optical Network with the historical records of the Royal Greenwich Observatory. This implementation affects modeled irradiances from 1882 - 1978. Second, the impact of a revised record of sunspot number by the Sunspot Index and Long-term Solar Observations center on modeled irradiances was assessed. This implementation provides two different reconstructions of historical, yearly-averaged irradiances from 1610-1881. Additionally, we show new, preliminary results that demonstrate improvements in modeled TSI by using

Planetary tides during the Maunder sunspot minimum

International Nuclear Information System (INIS)

Smythe, C.M.; Eddy, J.A.

1977-01-01

Sun-centered planetary conjunctions and tidal potentials are here constructed for the AD1645 to 1715 period of sunspot absence, referred to as the 'Maunder Minimum'. These are found to be effectively indistinguishable from patterns of conjunctions and power spectra of tidal potential in the present era of a well established 11 year sunspot cycle. This places a new and difficult restraint on any tidal theory of sunspot formation. Problems arise in any direct gravitational theory due to the apparently insufficient forces and tidal heights involved. Proponents of the tidal hypothesis usually revert to trigger mechanisms, which are difficult to criticise or test by observation. Any tidal theory rests on the evidence of continued sunspot periodicity and the substantiation of a prolonged period of solar anomaly in the historical past. The 'Maunder Minimum' was the most drastic change in the behaviour of solar activity in the last 300 years; sunspots virtually disappeared for a 70 year period and the 11 year cycle was probably absent. During that time, however, the nine planets were all in their orbits, and planetary conjunctions and tidal potentials were indistinguishable from those of the present era, in which the 11 year cycle is well established. This provides good evidence against the tidal theory. The pattern of planetary tidal forces during the Maunder Minimum was reconstructed to investigate the possibility that the multiple planet forces somehow fortuitously cancelled at the time, that is that the positions of the slower moving planets in the 17th and early 18th centuries were such that conjunctions and tidal potentials were at the time reduced in number and force. There was no striking dissimilarity between the time of the Maunder Minimum and any period investigated. The failure of planetary conjunction patterns to reflect the drastic drop in sunspots during the Maunder Minimum casts doubt on the tidal theory of solar activity, but a more quantitative test

A comparative study of semi-empirical interionic potentials for alkali halides - II

International Nuclear Information System (INIS)

Khwaja, F.A.; Naqvi, S.H.

1985-08-01

A comprehensive study of some semi-empirical interionic potentials is carried out through the calculation of the cohesive energy, relative stability and pressure induced solid-solid phase transformations in alkali halides. The theoretical values of these properties of the alkali halides are obtained using a new set of van der Waals coefficients and zero-point energy in the expression for interionic potential. From the comparison of the present calculations with some previous sophisticated ab-initio quantum-mechanical calculations and other semi-empirical approaches, it is concluded that the present calculations in the simplest central pairwise interaction description with the new values of the van der Waals coefficients and zero-point energy are in better agreement with the experimental data than the previous calculations. It is also concluded that in some cases the better choice of the interionic potential alone in the simplest semi-empirical picture of interaction gives an agreement of the theoretical predictions with the experimental data much superior to the ab-initio quantum mechanical approaches. (author)

Statistics of the largest sunspot and facular areas per solar cycle

International Nuclear Information System (INIS)

Willis, D.M.; Kabasakal Tulunay, Y.

1979-01-01

The statistics of extreme values is used to investigate the statistical properties of the largest areas sunspots and photospheric faculae per solar cycle. The largest values of the synodic-solar-rotation mean areas of umbrae, whole spots and faculae, which have been recorded for nine solar cycles, are each shown to comply with the general form of the extreme value probability function. Empirical expressions are derived for the three extreme value populations from which the characteristic statistical parameters, namely the mode, median, mean and standard deviation, can be calculated for each population. These three extreme value populations are also used to find the expected ranges of the extreme areas in a group of solar cycles as a function of the number of cycles in the group. The extreme areas of umbrae and whole spots have a dispersion comparable to that found by Siscoe for the extreme values of sunspot number, whereas the extreme areas of faculae have a smaller dispersion which is comparable to that found by Siscoe for the largest geomagnetic storm per solar cycle. The expected range of the largest sunspot area per solar cycle for a group of one hundred cycles appears to be inconsistent with the existence of the prolonged periods of sunspot minima that have been inferred from the historical information on solar variability. This inconsistency supports the contention that there are temporal changes of solar-cycle statistics during protracted periods of sunspot minima (or maxima). Indeed, without such temporal changes, photospheric faculae should have been continually observable throughout the lifetime of the Sun. (orig.)

Response of Solar Irradiance to Sunspot-area Variations

Science.gov (United States)

Dudok de Wit, T.; Kopp, G.; Shapiro, A.; Witzke, V.; Kretzschmar, M.

2018-02-01

One of the important open questions in solar irradiance studies is whether long-term variability (i.e., on timescales of years and beyond) can be reconstructed by means of models that describe short-term variability (i.e., days) using solar proxies as inputs. Preminger & Walton showed that the relationship between spectral solar irradiance and proxies of magnetic-flux emergence, such as the daily sunspot area, can be described in the framework of linear system theory by means of the impulse response. We significantly refine that empirical model by removing spurious solar-rotational effects and by including an additional term that captures long-term variations. Our results show that long-term variability cannot be reconstructed from the short-term response of the spectral irradiance, which questions the extension of solar proxy models to these timescales. In addition, we find that the solar response is nonlinear in a way that cannot be corrected simply by applying a rescaling to a sunspot area.

Semi-empirical neutron tool calibration (one and two-group approximation)

International Nuclear Information System (INIS)

Czubek, J.A.

1988-01-01

The physical principles of the new method of calibration of neutron tools for the rock porosity determination are given. A short description of the physics of neutron transport in the matter is presented together with some remarks on the elementary interactions of neutrons with nuclei (cross sections, group cross sections etc.). The definitions of the main integral parameters characterizing the neutron transport in the rock media are given. The three main approaches to the calibration problem: empirical, theoretical and semi-empirical are presented with some more detailed description of the latter one. The new semi-empirical approach is described. The method is based on the definition of the apparent slowing down or migration length for neutrons sensed by the neutron tool situated in the real borehole-rock conditions. To calculate this apparent slowing down or migration lengths the ratio of the proper space moments of the neutron distribution along the borehole axis is used. Theoretical results are given for one- and two-group diffusion approximations in the rock-borehole geometrical conditions when the tool is in the sidewall position. The physical and chemical parameters are given for the calibration blocks of the Logging Company in Zielona Gora. Using these data the neutron parameters of the calibration blocks have been calculated. An example, how to determine the calibration curve for the dual detector tool applying this new method and using the neutron parameters mentioned above together with the measurements performed in the calibration blocks, is given. The most important advantage of the new semi-empirical method of calibration is the possibility of setting on the unique calibration curve all experimental calibration data obtained for a given neutron tool for different porosities, lithologies and borehole diameters. 52 refs., 21 figs., 21 tabs. (author)

Diode laser heterodyne observations of silicon monoxide in sunspots - A test of three sunspot models

Science.gov (United States)

Glenar, D. A.; Deming, D.; Jennings, D. E.; Kostiuk, T.; Mumma, M. J.

1983-01-01

Absorption features from the 8 micron SiO fundamental (upsilon = 1-0) and hot bands (upsilon = 2-1) have been observed in sunspots at sub-Doppler resolution using a ground-based tunable diode laser heterodyne spectrometer. The observed line widths suggest an upper limit of 0.5 km/s for the microturbulent velocity in sunspot umbrae. Since the silicon monoxide abundance is very sensitive to sunspot temperature, the measured equivalent widths permit an unambiguous determination of the temperature-pressure relation in the upper layers of the umbral atmosphere. In the region of SiO line formation (log P sub g = 3.0-4.5), the results support the sunspot model suggested by Stellmacher and Wiehr (1970).

Theoretical Semi-Empirical AM1 studies of Schiff Bases

International Nuclear Information System (INIS)

Arora, K.; Burman, K.

2005-01-01

The present communication reports the theoretical semi-empirical studies of schiff bases of 2-amino pyridine along with their comparison with their parent compounds. Theoretical studies reveal that it is the azomethine group, in the schiff bases under study, that acts as site for coordination to metals as it is reported by many coordination chemists. (author)

Relationships between moment magnitude and fault parameters: theoretical and semi-empirical relationships

Science.gov (United States)

Wang, Haiyun; Tao, Xiaxin

2003-12-01

Fault parameters are important in earthquake hazard analysis. In this paper, theoretical relationships between moment magnitude and fault parameters including subsurface rupture length, downdip rupture width, rupture area, and average slip over the fault surface are deduced based on seismological theory. These theoretical relationships are further simplified by applying similarity conditions and an unique form is established. Then, combining the simplified theoretical relationships between moment magnitude and fault parameters with seismic source data selected in this study, a practical semi-empirical relationship is established. The seismic source data selected is also to used to derive empirical relationships between moment magnitude and fault parameters by the ordinary least square regression method. Comparisons between semi-empirical relationships and empirical relationships show that the former depict distribution trends of data better than the latter. It is also observed that downdip rupture widths of strike slip faults are saturated when moment magnitude is more than 7.0, but downdip rupture widths of dip slip faults are not saturated in the moment magnitude ranges of this study.

A simple semi-empirical approximation for bond energy

International Nuclear Information System (INIS)

Jorge, F.E.; Giambiagi, M.; Giambiagi, M.S. de.

1985-01-01

A simple semi-empirical expression for bond energy, related with a generalized bond index, is proposed and applied within the IEH framework. The correlation with experimental data is good for the intermolecular bond energy of base pairs of nucleic acids and other hydrogen bonded systems. The intramolecular bond energies for a sample of molecules containing typical bonds and for hydrides are discussed. The results are compared with those obtained by other methods. (Author) [pt

Semi-empirical calculations on the structure of the uronium ion

NARCIS (Netherlands)

Harkema, Sybolt

1972-01-01

Semi-empirical calculations (CNDO/2) on the structure of the uronium ion are presented. Assuming a planar ion with fixed bond lengths, the bond angles involving the heavy atoms can be calculated with fair accuracy. Changes in bond length and angles, which occur upon protonation of the urea molecule,

Self-affinity and nonextensivity of sunspots

International Nuclear Information System (INIS)

Moret, M.A.

2014-01-01

In this paper we study the time series of sunspots by using two different approaches, analyzing its self-affine behavior and studying its distribution. The long-range correlation exponent α has been calculated via Detrended Fluctuation Analysis and the power law vanishes to values greater than 11 years. On the other hand, the distribution of the sunspots obeys a q-exponential decay that suggests a non-extensive behavior. This observed characteristic seems to take an alternative interpretation of the sunspots dynamics. The present findings suggest us to propose a dynamic model of sunspots formation based on a nonlinear Fokker–Planck equation. Therefore its dynamic process follows the generalized thermostatistical formalism.

Tracking the Magnetic Flux in and Around Sunspots

Energy Technology Data Exchange (ETDEWEB)

Sheeley, N. R. Jr.; Stauffer, J. R.; Thomassie, J. C.; Warren, H. P., E-mail: solsheeley@verizon.net, E-mail: harry.warren@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)

2017-02-10

We have developed a procedure for tracking sunspots observed by the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory and for making curvature-corrected space/time maps of the associated line-of-sight magnetic field and continuum intensity. We apply this procedure to 36 sunspots, each observed continuously for nine days around its central meridian passage time, and find that the proper motions separate into two distinct components depending on their speeds. Fast (∼3–5 km s{sup −1}) motions, comparable to Evershed flows, are produced by weak vertical fluctuations of the horizontal canopy field and recur on a timescale of 12–20 min. Slow (∼0.3–0.5 km s{sup −1}) motions diverge from a sunspot-centered ring whose location depends on the size of the sunspot, occurring in the mid-penumbra for large sunspots and at the outer edge of the penumbra for small sunspots. The slow ingoing features are contracting spokes of a quasi-vertical field of umbral polarity. These inflows disappear when the sunspot loses its penumbra, and may be related to inward-moving penumbral grain. The slow outgoing features may have either polarity depending on whether they originate from quasi-vertical fields of umbral polarity or from the outer edge of the canopy. When a sunspot decays, the penumbra and canopy disappear, and the moat becomes filled with slow outflows of umbral polarity. We apply our procedure to decaying sunspots, to long-lived sunspots, and to numerical simulations of a long-lived sunspot by Rempel.

Semi-empirical formula for large pore-size estimation from o-Ps annihilation lifetime

International Nuclear Information System (INIS)

Nguyen Duc Thanh; Tran Quoc Dung; Luu Anh Tuyen; Khuong Thanh Tuan

2007-01-01

The o-Ps annihilation rate in large pore was investigated by the semi-classical approach. The semi-empirical formula that simply correlates between the pore size and the o-Ps lifetime was proposed. The calculated results agree well with experiment in the range from some angstroms to several ten nanometers size of pore. (author)

Probing sunspots with two-skip time-distance helioseismology

Science.gov (United States)

Duvall, Thomas L., Jr.; Cally, Paul S.; Przybylski, Damien; Nagashima, Kaori; Gizon, Laurent

2018-06-01

Context. Previous helioseismology of sunspots has been sensitive to both the structural and magnetic aspects of sunspot structure. Aims: We aim to develop a technique that is insensitive to the magnetic component so the two aspects can be more readily separated. Methods: We study waves reflected almost vertically from the underside of a sunspot. Time-distance helioseismology was used to measure travel times for the waves. Ray theory and a detailed sunspot model were used to calculate travel times for comparison. Results: It is shown that these large distance waves are insensitive to the magnetic field in the sunspot. The largest travel time differences for any solar phenomena are observed. Conclusions: With sufficient modeling effort, these should lead to better understanding of sunspot structure.

A semi-empirical model for predicting crown diameter of cedrela ...

African Journals Online (AJOL)

A semi-empirical model relating age and breast height has been developed to predict individual tree crown diameter for Cedrela odorata (L) plantation in the moist evergreen forest zones of Ghana. The model was based on field records of 269 trees, and could determine the crown cover dynamics, forecast time of canopy ...

Semi-empirical Determination of Detection Efficiency for Voluminous Source by Effective Solid Angle Method

Energy Technology Data Exchange (ETDEWEB)

Kang, M. Y.; Kim, J. H.; Choi, H. D. [Seoul National Univ., Seoul (Korea, Republic of); Sun, G. M. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

In the field of γ-ray measurements, the determination of full energy (FE) absorption peak efficiency for a voluminous sample is difficult, because the preparation of the certified radiation source with the same chemical composition and geometry for the original voluminous sample is not easy. In order to solve this inconvenience, simulation or semi-empirical methods are preferred in many cases. Effective Solid Angle (ESA) Code which includes semi-empirical approach has been developed by the Applied Nuclear Physics Group in Seoul National University. In this study, we validated ESA code by using Marinelli type voluminous KRISS (Korea Research Institute of Standards and Science) CRM (Certified Reference Materials) sources and IAEA standard γ-ray point sources. And semi-empirically determined efficiency curve for voluminous source by using the ESA code is compared with the experimental value. We calculated the efficiency curve of voluminous source from the measured efficiency of standard point source by using the ESA code. We will carry out the ESA code validation by measurement of various CRM volume sources with detector of different efficiency.

Featured Image: Bright Dots in a Sunspot

Science.gov (United States)

Kohler, Susanna

2018-03-01

This image of a sunspot, located in in NOAA AR 12227, was captured in December 2014 by the 0.5-meter Solar Optical Telescope on board the Hinode spacecraft. This image was processed by a team of scientists led by Rahul Yadav (Udaipur Solar Observatory, Physical Research Laboratory Dewali, India) in order to examine the properties of umbral dots: transient, bright features observed in the umbral region (the central, darkest part) of a sunspot. By exploring these dots, Yadav and collaborators learned how their properties relate to the large-scale properties of the sunspots in which they form for instance, how do the number, intensities, or filling factors of dots relate to the size of a sunspots umbra? To find out more about the authors results, check out the article below.Sunspot in NOAA AR 11921. Left: umbralpenumbral boundary. Center: the isolated umbra from the sunspot. Right: The umbra with locations of umbral dots indicated by yellow plus signs. [Adapted from Yadav et al. 2018]CitationRahul Yadav et al 2018 ApJ 855 8. doi:10.3847/1538-4357/aaaeba

Identification of possible intense historical geomagnetic storms using combined sunspot and auroral observations from East Asia

Directory of Open Access Journals (Sweden)

D. M. Willis

2005-03-01

Full Text Available Comprehensive catalogues of ancient sunspot and auroral observations from East Asia are used to identify possible intense historical geomagnetic storms in the interval 210 BC-AD 1918. There are about 270 entries in the sunspot catalogue and about 1150 entries in the auroral catalogue. Special databases have been constructed in which the scientific information in these two catalogues is placed in specified fields. For the purposes of this study, an historical geomagnetic storm is defined in terms of an auroral observation that is apparently associated with a particular sunspot observation, in the sense that the auroral observation occurred within several days of the sunspot observation. More precisely, a selection criterion is formulated for the automatic identification of such geomagnetic storms, using the oriental records stored in the sunspot and auroral databases. The selection criterion is based on specific assumptions about the duration of sunspot visibility with the unaided eye, the likely range of heliographic longitudes of an energetic solar feature, and the likely range of transit times for ejected solar plasma to travel from the Sun to the Earth. This selection criterion results in the identification of nineteen putative historical geomagnetic storms, although two of these storms are spurious in the sense that there are two examples of a single sunspot observation being associated with two different auroral observations separated by more than half a (synodic solar rotation period. The literary and scientific reliabilities of the East Asian sunspot and auroral records that define the nineteen historical geomagnetic storms are discussed in detail in a set of appendices. A possible time sequence of events is presented for each geomagnetic storm, including possible dates for both the central meridian passage of the sunspot and the occurrence of the energetic solar feature, as well as likely transit times for the ejected solar plasma

Sunspot drawings handwritten character recognition method based on deep learning

Science.gov (United States)

Zheng, Sheng; Zeng, Xiangyun; Lin, Ganghua; Zhao, Cui; Feng, Yongli; Tao, Jinping; Zhu, Daoyuan; Xiong, Li

2016-05-01

High accuracy scanned sunspot drawings handwritten characters recognition is an issue of critical importance to analyze sunspots movement and store them in the database. This paper presents a robust deep learning method for scanned sunspot drawings handwritten characters recognition. The convolution neural network (CNN) is one algorithm of deep learning which is truly successful in training of multi-layer network structure. CNN is used to train recognition model of handwritten character images which are extracted from the original sunspot drawings. We demonstrate the advantages of the proposed method on sunspot drawings provided by Chinese Academy Yunnan Observatory and obtain the daily full-disc sunspot numbers and sunspot areas from the sunspot drawings. The experimental results show that the proposed method achieves a high recognition accurate rate.

Semi-empirical and empirical L X-ray production cross sections for elements with 50 ≤ Z ≤ 92 for protons of 0.5-3.0 MeV

International Nuclear Information System (INIS)

Nekab, M.; Kahoul, A.

2006-01-01

We present in this contribution, semi-empirical production cross sections of the main X-ray lines Lα, Lβ and Lγ for elements from Sn to U and for protons with energies varying from 0.5 to 3.0 MeV. The theoretical X-ray production cross sections are firstly calculated from the theoretical ionization cross sections of the Li (i = 1, 2, 3) subshell within the ECPSSR theory. The semi-empirical Lα, Lβ and Lγ cross sections are then deduced by fitting the available experimental data normalized to their corresponding theoretical values and give the better representation of the experimental data in some cases. On the other hand, the experimental data are directly fitted to deduce the empirical L X-ray production cross sections. A comparison is made between the semi-empirical cross sections, the empirical cross sections reported in this work and the empirical ones reported by Reis and Jesus [M.A. Reis, A.P. Jesus, Atom. Data Nucl. Data Tables 63 (1996) 1] and those of Strivay and Weber [Strivay, G. Weber, Nucl. Instr. and Meth. B 190 (2002) 112

Association of Plages with Sunspots: A Multi-Wavelength Study Using Kodaikanal Ca ii K and Greenwich Sunspot Area Data

Energy Technology Data Exchange (ETDEWEB)

Mandal, Sudip; Chatterjee, Subhamoy; Banerjee, Dipankar, E-mail: sudip@iiap.res.in [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India)

2017-02-01

Plages are the magnetically active chromospheric structures prominently visible in the Ca ii K line (3933.67 Å). A plage may or may not be associated with a sunspot, which is a magnetic structure visible in the solar photosphere. In this study we explore this aspect of association of plages with sunspots using the newly digitized Kodaikanal Ca ii K plage data and the Greenwich sunspot area data. Instead of using the plage index or fractional plage area and its comparison with the sunspot number, we use, to our knowledge for the first time, the individual plage areas and compare them with the sunspot area time series. Our analysis shows that these two structures, formed in two different layers, are highly correlated with each other on a timescale comparable to the solar cycle. The area and the latitudinal distributions of plages are also similar to those of sunspots. Different area thresholdings on the “butterfly diagram” reveal that plages of area ≥4 arcmin{sup 2} are mostly associated with a sunspot in the photosphere. Apart from this, we found that the cyclic properties change when plages of different sizes are considered separately. These results may help us to better understand the generation and evolution of the magnetic structures in different layers of the solar atmosphere.

HELIOSEISMOLOGY OF A REALISTIC MAGNETOCONVECTIVE SUNSPOT SIMULATION

International Nuclear Information System (INIS)

Braun, D. C.; Birch, A. C.; Rempel, M.; Duvall, T. L. Jr.

2012-01-01

We compare helioseismic travel-time shifts measured from a realistic magnetoconvective sunspot simulation using both helioseismic holography and time-distance helioseismology, and measured from real sunspots observed with the Helioseismic and Magnetic Imager instrument on board the Solar Dynamics Observatory and the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observatory. We find remarkable similarities in the travel-time shifts measured between the methodologies applied and between the simulated and real sunspots. Forward modeling of the travel-time shifts using either Born or ray approximation kernels and the sound-speed perturbations present in the simulation indicates major disagreements with the measured travel-time shifts. These findings do not substantially change with the application of a correction for the reduction of wave amplitudes in the simulated and real sunspots. Overall, our findings demonstrate the need for new methods for inferring the subsurface structure of sunspots through helioseismic inversions.

Fractal Dimension and Maximum Sunspot Number in Solar Cycle

Directory of Open Access Journals (Sweden)

R.-S. Kim

2006-09-01

Full Text Available The fractal dimension is a quantitative parameter describing the characteristics of irregular time series. In this study, we use this parameter to analyze the irregular aspects of solar activity and to predict the maximum sunspot number in the following solar cycle by examining time series of the sunspot number. For this, we considered the daily sunspot number since 1850 from SIDC (Solar Influences Data analysis Center and then estimated cycle variation of the fractal dimension by using Higuchi's method. We examined the relationship between this fractal dimension and the maximum monthly sunspot number in each solar cycle. As a result, we found that there is a strong inverse relationship between the fractal dimension and the maximum monthly sunspot number. By using this relation we predicted the maximum sunspot number in the solar cycle from the fractal dimension of the sunspot numbers during the solar activity increasing phase. The successful prediction is proven by a good correlation (r=0.89 between the observed and predicted maximum sunspot numbers in the solar cycles.

Sunspot Positions and Areas from Observations by Galileo Galilei

Science.gov (United States)

Vokhmyanin, M. V.; Zolotova, N. V.

2018-02-01

Sunspot records in the seventeenth century provide important information on the solar activity before the Maunder minimum, yielding reliable sunspot indices and the solar butterfly diagram. Galilei's letters to Cardinal Francesco Barberini and Marcus Welser contain daily solar observations on 3 - 11 May, 2 June - 8 July, and 19 - 21 August 1612. These historical archives do not provide the time of observation, which results in uncertainty in the sunspot coordinates. To obtain them, we present a method that minimizes the discrepancy between the sunspot latitudes. We provide areas and heliographic coordinates of 82 sunspot groups. In contrast to Sheiner's butterfly diagram, we found only one sunspot group near the Equator. This provides a higher reliability of Galilei's drawings. Large sunspot groups are found to emerge at the same longitude in the northern hemisphere from 3 May to 21 August, which indicates an active longitude.

On the relation between activity-related frequency shifts and the sunspot distribution over the solar cycle 23

Directory of Open Access Journals (Sweden)

Santos Ângela R. G.

2017-01-01

Full Text Available The activity-related variations in the solar acoustic frequencies have been known for 30 years. However, the importance of the different contributions is still not well established. With this in mind, we developed an empirical model to estimate the spot-induced frequency shifts, which takes into account the sunspot properties, such as area and latitude. The comparison between the model frequency shifts obtained from the daily sunspot records and those observed suggests that the contribution from a stochastic component to the total frequency shifts is about 30%. The remaining 70% is related to a global, long-term variation. We also propose a new observable to investigate the short-and mid-term variations of the frequency shifts, which is insensitive to the long-term variations contained in the data. On the shortest time scales the variations in the frequency shifts are strongly correlated with the variations in the total area covered by sunspots. However, a significant loss of correlation is still found, which cannot be fully explained by ignoring the invisible side of the Sun when accounting for the total sunspot area. We also verify that the times when the frequency shifts and the sunspot areas do not vary in a similar way tend to coincide with the times of the maximum amplitude of the quasi-biennial variations found in the seismic data.

Full energy peak efficiency of NaI(Tl) gamma detectors and its analytical and semi-empirical representations

International Nuclear Information System (INIS)

Sudarshan, M.; Joseph, J.; Singh, R.

1992-01-01

The validity of various analytical functions and semi-empirical formulae proposed for representing the full energy peak efficiency (FEPE) curves of Ge(Li) and HPGe detectors has been tested for the FEPE of 7.6 cm x 7.6 cm and 5 cm x 5 cm Nal(Tl) detectors in the gamma energy range from 59.5 to 1408.03 keV. The functions proposed by East, and McNelles and Campbell provide by far the best representations of the present data. The semi-empirical formula of Mowatt describes the present data very well. The present investigation shows that some of the analytical functions and semi-empirical formulae, which represent the FEPE of the Ge(Li) and HPGe detectors very well, can be quite fruitfully used for Nal(Tl) detectors. (Author)

Towards the automatic detection and analysis of sunspot rotation

Science.gov (United States)

Brown, Daniel S.; Walker, Andrew P.

2016-10-01

Torsional rotation of sunspots have been noted by many authors over the past century. Sunspots have been observed to rotate up to the order of 200 degrees over 8-10 days, and these have often been linked with eruptive behaviour such as solar flares and coronal mass ejections. However, most studies in the literature are case studies or small-number studies which suffer from selection bias. In order to better understand sunspot rotation and its impact on the corona, unbiased large-sample statistical studies are required (including both rotating and non-rotating sunspots). While this can be done manually, a better approach is to automate the detection and analysis of rotating sunspots using robust methods with well characterised uncertainties. The SDO/HMI instrument provide long-duration, high-resolution and high-cadence continuum observations suitable for extracting a large number of examples of rotating sunspots. This presentation will outline the analysis of SDI/HMI data to determine the rotation (and non-rotation) profiles of sunspots for the complete duration of their transit across the solar disk, along with how this can be extended to automatically identify sunspots and initiate their analysis.

Semi-empirical atom-atom interaction models and X-ray crystallography

International Nuclear Information System (INIS)

Braam, A.W.M.

1981-01-01

Several aspects of semi-empirical energy calculations in crystallography are considered. Solid modifications of ethane have been studied using energy calculations and a fast summation technique has been evaluated. The structure of tetramethylpyrazine has been determined at room temperature and at 100K and accurate structure factors have been derived from measured Bragg intensities. Finally electrostatic properties have been deduced from X-ray structure factors. (C.F.)

The Sunspot Number and beyond : reconstructing detailed solar information over centuries

Science.gov (United States)

Lefevre, L.

2014-12-01

With four centuries of solar evolution, the International Sunspot Number (SSN) forms the longest solar time series currently available. It provides an essential reference for understanding and quantifying how the solar output has varied over decades and centuries and thus for assessing the variations of the main natural forcing on the Earth climate. Because of its importance, this unique time-series must be closely monitored for any possible biases and drifts. Here, we report about recent disagreements between solar indices, for example the sunspot sumber and the 10.7cm radio flux. Recent analyses indicate that while part of this divergence may be due to a calibration drift in the SSN, it also results from an intrinsic change in the global magnetic parameters of sunspots and solar active regions, suggesting a possible transition to a new activity regime. Going beyond the SSN series, in the framework of the TOSCA (www.cost-tosca.eu/) and SOLID (projects.pmodwrc.ch/solid/) projects, we produced a survey of all existing catalogs providing detailed sunspot information (Lefevre & Clette, 2014:10.1007/s11207-012-0184-5) and we also located different primary solar images and drawing collections that can be exploitable to complement the existing catalogs. These are first steps towards the construction of a multi-parametric time series of multiple sunspot and sunspot group properties over more than a century, allowing to reconstruct and extend the current 1-D SSN series. By bringing new spatial, morphological and evolutionary information, such a data set should bring major advances for the modeling of the solar dynamo and solar irradiance. We will present here the current status of this work. The preliminary version catalog now extends over the last 150 years. It makes use of data from DPD (http://fenyi.solarobs.unideb.hu/DPD/index.html), from the Uccle Solar Equatorial Table (USET:http://sidc.oma.be/uset/) operated by the Royal Obeservatory of Belgium, the Greenwich

An essay on sunspots and solar flares

International Nuclear Information System (INIS)

Akasofu, S.-I.

1984-01-01

The presently prevailing theories of sunspots and solar flares rely on the hypothetical presence of magnetic flux tubes beneath the photosphere and the two subsequent hypotheses, their emergence above the photosphere and explosive magnetic reconnection, converting magnetic energy carried by the flux tubes for solar flare energy. In this paper, attention is paid to the fact that there are large-scale magnetic fields which divide the photosphere into positive and negative (line-of-sight) polarity regions and that they are likely to be more fundamental than sunspot fields, as emphasized most recently by McIntosh. A new phenomenological model of the sunspot pair formation is then constructed by considering an amplification process of these large-scale fields near their boundaries by shear flows, including localized vortex motions. The amplification results from a dynamo process associated with such vortex flows and the associated convergence flow in the large-scale fields. This dynamo process generates also some of the familiar ''force-free'' fields or the ''sheared'' magnetic fields in which the magnetic field-aligned currents are essential. Upward field-aligned currents generated by the dynamo process are carried by downward streaming electrons which are expected to be accelerated by an electric potential structure; a similar structure is responsible for accelerating auroral electrons in the magnetosphere. Depending on the magnetic field configuration and the shear flows, the current-carrying electrons precipitate into different geometrical patterns, causing circular flares, umbral flares, two-ribbon flares, etc. Thus, it is suggested that ''low temperature flares'' are directly driven by the photospheric dynamo process. (author)

The reconciliation of an F-region irregularity model with sunspot-cycle variations in spread-F occurrence

International Nuclear Information System (INIS)

Singleton, D.G.

1974-11-01

A recently proposed means of combining models of ionospheric F-layer peak electron density and irregularity incremental electron density (ΔN) so as to simulate the global occurrence probability of the frequency spreading component of spread-F is discussed. This procedure is then used to model experimental spread-F occurrence results. It is found possible to readily simulate the sunspot-maximum results, independently of season, with only small adjustments to the amplitudes of the empirical expressions used to ΔN in the several latitude regimes. However, at sunspot minimum and for each season, the ΔN model requires modification in the equatorial and mid-latitude regions of high irregularity incidence, before successful simulations of the spread-F data can be obtained. These modifications, which include a broadening of the equatorial region and a polewards shift to the mid-latitude region with decreasing sunspot number, are discussed in detail. It is concluded that the scintillation data base, from which the original ΔN model derives, is not sufficiently representative with regard to sunspot number and magnetic index. The use of the spread-F adaptation of the ΔN model, as well as its original scintillation version, to rectify these failings of the ΔN model are also discussed. (author)

Oscillations and Waves in Sunspots

Directory of Open Access Journals (Sweden)

Elena Khomenko

2015-11-01

Full Text Available A magnetic field modifies the properties of waves in a complex way. Significant advances have been made recently in our understanding of the physics of sunspot waves with the help of high-resolution observations, analytical theories, as well as numerical simulations. We review the current ideas in the field, providing the most coherent picture of sunspot oscillations as by present understanding.

Interface of the polarizable continuum model of solvation with semi-empirical methods in the GAMESS program

DEFF Research Database (Denmark)

Svendsen, Casper Steinmann; Blædel, Kristoffer L.; Christensen, Anders Steen

2013-01-01

An interface between semi-empirical methods and the polarized continuum model (PCM) of solvation successfully implemented into GAMESS following the approach by Chudinov et al (Chem. Phys. 1992, 160, 41). The interface includes energy gradients and is parallelized. For large molecules such as ubiq......An interface between semi-empirical methods and the polarized continuum model (PCM) of solvation successfully implemented into GAMESS following the approach by Chudinov et al (Chem. Phys. 1992, 160, 41). The interface includes energy gradients and is parallelized. For large molecules...

Semi-empirical calculations for the ranges of fast ions in silicon

Science.gov (United States)

Belkova, Yu. A.; Teplova, Ya. A.

2018-04-01

A semi-empirical method is proposed to calculate the ion ranges in energy region E = 0.025-10 MeV/nucleon. The dependence of ion ranges on the projectile nuclear charge, mass and velocity is analysed. The calculations presented for ranges of ions with nuclear charges Z = 2-10 in silicon are compared with SRIM results and experimental data.

The sunspot databases of the Debrecen Observatory

Science.gov (United States)

Baranyi, Tünde; Gyori, Lajos; Ludmány, András

2015-08-01

We present the sunspot data bases and online tools available in the Debrecen Heliophysical Observatory: the DPD (Debrecen Photoheliographic Data, 1974 -), the SDD (SOHO/MDI-Debrecen Data, 1996-2010), the HMIDD (SDO/HMI-Debrecen Data, HMIDD, 2010-), the revised version of Greenwich Photoheliographic Data (GPR, 1874-1976) presented together with the Hungarian Historical Solar Drawings (HHSD, 1872-1919). These are the most detailed and reliable documentations of the sunspot activity in the relevant time intervals. They are very useful for studying sunspot group evolution on various time scales from hours to weeks. Time-dependent differences between the available long-term sunspot databases are investigated and cross-calibration factors are determined between them. This work has received funding from the European Community's Seventh Framework Programme (FP7/2012-2015) under grant agreement No. 284461 (eHEROES).

The Strongest Magnetic Field in Sunspots

Science.gov (United States)

Okamoto, J.; Sakurai, T.

2017-12-01

Sunspots are concentrations of magnetic fields on the solar surface. Generally, the strongest magnetic field in each sunspot is located in the dark umbra in most cases. A typical field strength in sunspots is around 3,000 G. On the other hand, some exceptions also have been found in complex sunspots with bright regions such as light bridges that separate opposite polarity umbrae, for instance with a strength of 4,300 G. However, the formation mechanism of such strong fields outside umbrae is still puzzling. Here we report an extremely strong magnetic field in a sunspot, which was located in a bright region sandwiched by two opposite-polarity umbrae. The strength is 6,250 G, which is the largest ever observed since the discovery of magnetic field on the Sun in 1908 by Hale. We obtained 31 scanned maps of the active region observed by Hinode/SOT/SP with a cadence of 3 hours over 5 days (February 1-6, 2014). Considering the spatial and temporal evolution of the vector magnetic field and the Doppler velocity in the bright region, we suggested that this strong field region was generated as a result of compression of one umbra pushed by the outward flow from the other umbra (Evershed flow), like the subduction of the Earth's crust in plate tectonics.

Solar rotation and meridional motions derived from sunspot groups

International Nuclear Information System (INIS)

Tuominen, J.; Tuominen, I.; Kyroelaeinen, J.

1982-01-01

Latitudinal and longitudinal motions of sunspot groups have been studied using the positions of recurrent sunspot groups of 103 years published by Greenwich observatory. In order to avoid any limb effects, only positions close to the central meridian have been used. The data were divided into two parts: those belonging to the years around sunspot maxima and those belonging to the years around sunspot minima. Using several different criteria it was ascertained that sunspot groups show meridional motions and that their drift curves as a function of latitude are different around maxima and around minima. In addition, also the angular velocity, as a function of latitude, was found to be different around maxima and minima. (Auth.)

Sunspot Modeling: From Simplified Models to Radiative MHD Simulations

Directory of Open Access Journals (Sweden)

Rolf Schlichenmaier

2011-09-01

Full Text Available We review our current understanding of sunspots from the scales of their fine structure to their large scale (global structure including the processes of their formation and decay. Recently, sunspot models have undergone a dramatic change. In the past, several aspects of sunspot structure have been addressed by static MHD models with parametrized energy transport. Models of sunspot fine structure have been relying heavily on strong assumptions about flow and field geometry (e.g., flux-tubes, "gaps", convective rolls, which were motivated in part by the observed filamentary structure of penumbrae or the necessity of explaining the substantial energy transport required to maintain the penumbral brightness. However, none of these models could self-consistently explain all aspects of penumbral structure (energy transport, filamentation, Evershed flow. In recent years, 3D radiative MHD simulations have been advanced dramatically to the point at which models of complete sunspots with sufficient resolution to capture sunspot fine structure are feasible. Here overturning convection is the central element responsible for energy transport, filamentation leading to fine-structure and the driving of strong outflows. On the larger scale these models are also in the progress of addressing the subsurface structure of sunspots as well as sunspot formation. With this shift in modeling capabilities and the recent advances in high resolution observations, the future research will be guided by comparing observation and theory.

INTERFERENCE FRINGES OF SOLAR ACOUSTIC WAVES AROUND SUNSPOTS

Energy Technology Data Exchange (ETDEWEB)

Chou, Dean-Yi; Zhao Hui; Yang, Ming-Hsu; Liang, Zhi-Chao, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)

2012-10-20

Solar acoustic waves are scattered by a sunspot due to the interaction between the acoustic waves and the sunspot. The sunspot, excited by the incident wave, generates the scattered wave. The scattered wave is added to the incident wave to form the total wave around the sunspot. The interference fringes between the scattered wave and the incident wave are visible in the intensity of the total wave because the coherent time of the incident wave is of the order of a wave period. The strength of the interference fringes anti-correlates with the width of temporal spectra of the incident wave. The separation between neighboring fringes increases with the incident wavelength and the sunspot size. The strength of the fringes increases with the radial order n of the incident wave from n = 0 to n = 2, and then decreases from n = 2 to n = 5. The interference fringes play a role analogous to holograms in optics. This study suggests the feasibility of using the interference fringes to reconstruct the scattered wavefields of the sunspot, although the quality of the reconstructed wavefields is sensitive to the noise and errors in the interference fringes.

Iwahashi Zenbei's Sunspot Drawings in 1793 in Japan

Science.gov (United States)

Hayakawa, Hisashi; Iwahashi, Kiyomi; Tamazawa, Harufumi; Toriumi, Shin; Shibata, Kazunari

2018-01-01

Three Japanese sunspot drawings associated with Iwahashi Zenbei (1756 - 1811) are shown here from contemporary manuscripts and woodprint documents with the relevant texts. We reveal the observational date of one of the drawings to be 26 August 1793, and the overall observations lasted for over a year. Moreover, we identify the observational site for the dated drawing as Fushimi in Japan. We then compare Zenbei's observations with the group sunspot number and the raw group count from the Sunspot Index and Long-term Solar Observations (SILSO) to reveal the context of the data, and we conclude that these drawings fill gaps in our understanding that are due to the fragmental sunspot observations around 1793. These drawings are important as a clue to evaluate astronomical knowledge of contemporary Japan in the late eighteenth century and are valuable as a non-European observation, considering that most sunspot observations up to the middle of the nineteenth century are from Europe.

Sunspots During the Maunder Minimum from Machina Coelestis by Hevelius

Science.gov (United States)

Carrasco, V. M. S.; Álvarez, J. Villalba; Vaquero, J. M.

2015-10-01

We revisited the sunspot observations published by Johannes Hevelius in his book Machina Coelestis (1679) corresponding to the period of 1653 - 1675 (just in the middle of the Maunder Minimum). We show detailed translations of the original Latin texts describing the sunspot records and provide the general context of these sunspot observations. From this source, we present an estimate of the annual values of the group sunspot number based only on the records that explicitly inform us of the presence or absence of sunspots. Although we obtain very low values of the group sunspot number, in accordance with a grand minimum of solar activity, these values are significantly higher in general than the values provided by Hoyt and Schatten ( Solar Phys. 179, 189, 1998) for the same period.

Empirical research on constructing Taiwan's ecoenvironmental ...

African Journals Online (AJOL)

In this paper, the material flow indicators and ecological footprint approach structured are adopted to construct eco-environmental stress indicators. We use relevant data to proceed with the empirical analyses on environmental stress and ecological impacts in Taiwan between the years of 1998 and 2007. Analysis of ...

HELIOSEISMIC HOLOGRAPHY OF SIMULATED SUNSPOTS: MAGNETIC AND THERMAL CONTRIBUTIONS TO TRAVEL TIMES

Energy Technology Data Exchange (ETDEWEB)

Felipe, T. [Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife (Spain); Braun, D. C.; Crouch, A. D. [NorthWest Research Associates, Colorado Research Associates, Boulder, CO 80301 (United States); Birch, A. C., E-mail: tobias@iac.es [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

2016-10-01

Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

HELIOSEISMIC HOLOGRAPHY OF SIMULATED SUNSPOTS: MAGNETIC AND THERMAL CONTRIBUTIONS TO TRAVEL TIMES

International Nuclear Information System (INIS)

Felipe, T.; Braun, D. C.; Crouch, A. D.; Birch, A. C.

2016-01-01

Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

On the insignificance of Herschel's sunspot correlation

Science.gov (United States)

Love, Jeffrey J.

2013-08-01

We examine William Herschel's hypothesis that solar-cycle variation of the Sun's irradiance has a modulating effect on the Earth's climate and that this is, specifically, manifested as an anticorrelation between sunspot number and the market price of wheat. Since Herschel first proposed his hypothesis in 1801, it has been regarded with both interest and skepticism. Recently, reports have been published that either support Herschel's hypothesis or rely on its validity. As a test of Herschel's hypothesis, we seek to reject a null hypothesis of a statistically random correlation between historical sunspot numbers, wheat prices in London and the United States, and wheat farm yields in the United States. We employ binary-correlation, Pearson-correlation, and frequency-domain methods. We test our methods using a historical geomagnetic activity index, well known to be causally correlated with sunspot number. As expected, the measured correlation between sunspot number and geomagnetic activity would be an unlikely realization of random data; the correlation is "statistically significant." On the other hand, measured correlations between sunspot number and wheat price and wheat yield data would be very likely realizations of random data; these correlations are "insignificant." Therefore, Herschel's hypothesis must be regarded with skepticism. We compare and contrast our results with those of other researchers. We discuss procedures for evaluating hypotheses that are formulated from historical data.

Data mining of Ti-Al semi-empirical parameters for developing reduced order models

Energy Technology Data Exchange (ETDEWEB)

Broderick, Scott R [Department of Materials Science and Engineering and Institute for Combinatorial Discovery, Iowa State University, Ames, IA 50011 (United States); Aourag, Hafid [Department of Physics, University Abou Bakr Belkaid, Tlemcen 13000 (Algeria); Rajan, Krishna [Department of Materials Science and Engineering and Institute for Combinatorial Discovery, Iowa State University, Ames, IA 50011 (United States)

2011-05-15

A focus of materials design is determining the minimum amount of information necessary to fully describe a system, thus reducing the number of empirical results required and simplifying the data analysis. Screening descriptors calculated through a semi-empirical model, we demonstrate how an informatics-based analysis can be used to address this issue with no prior assumptions. We have developed a unique approach for identifying the minimum number of descriptors necessary to capture all the information of a system. Using Ti-Al alloys of varying compositions and crystal chemistries as the test bed, 5 of the 21 original descriptors from electronic structure calculations are found to capture all the information from the calculation, thereby reducing the structure-chemistry-property search space. Additionally, by combining electronic structure calculations with data mining, we classify the systems by chemistries and structures, based on the electronic structure inputs, and thereby rank the impact of change in chemistry and crystal structure on the electronic structure. -- Research Highlights: {yields} We developed an informatics-based methodology to minimize the necessary information. {yields} We applied this methodology to descriptors from semi-empirical calculations. {yields} We developed a validation approach for maintaining information from screening. {yields} We classified intermetallics and identified patterns of composition and structure.

Data mining of Ti-Al semi-empirical parameters for developing reduced order models

International Nuclear Information System (INIS)

Broderick, Scott R.; Aourag, Hafid; Rajan, Krishna

2011-01-01

A focus of materials design is determining the minimum amount of information necessary to fully describe a system, thus reducing the number of empirical results required and simplifying the data analysis. Screening descriptors calculated through a semi-empirical model, we demonstrate how an informatics-based analysis can be used to address this issue with no prior assumptions. We have developed a unique approach for identifying the minimum number of descriptors necessary to capture all the information of a system. Using Ti-Al alloys of varying compositions and crystal chemistries as the test bed, 5 of the 21 original descriptors from electronic structure calculations are found to capture all the information from the calculation, thereby reducing the structure-chemistry-property search space. Additionally, by combining electronic structure calculations with data mining, we classify the systems by chemistries and structures, based on the electronic structure inputs, and thereby rank the impact of change in chemistry and crystal structure on the electronic structure. -- Research Highlights: → We developed an informatics-based methodology to minimize the necessary information. → We applied this methodology to descriptors from semi-empirical calculations. → We developed a validation approach for maintaining information from screening. → We classified intermetallics and identified patterns of composition and structure.

RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

Energy Technology Data Exchange (ETDEWEB)

McClintock, B. H. [University of Southern Queensland, Toowoomba, 4350 (Australia); Norton, A. A. [HEPL, Stanford University, Palo Alto, CA 94305 (United States); Li, J., E-mail: u1049686@umail.usq.edu.au, E-mail: aanorton@stanford.edu, E-mail: jli@igpp.ucla.edu [Department of Earth, Planetary, and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095 (United States)

2014-12-20

Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators.

RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

International Nuclear Information System (INIS)

McClintock, B. H.; Norton, A. A.; Li, J.

2014-01-01

Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators

Semi-empirical modelization of charge funneling in a NP diode

International Nuclear Information System (INIS)

Musseau, O.

1991-01-01

Heavy ion interaction with a semiconductor generates a high density of electrons and holes pairs along the trajectory and in a space charge zone the collected charge is considerably increased. The chronology of this charge funneling is described in a semi-empirical model. From initial conditions characterizing the incident ion and the studied structure, it is possible to evaluate directly the transient current, the collected charge and the length of funneling with a good agreement. The model can be extrapolated to more complex structures

Sunspots Resource--From Ancient Cultures to Modern Research

Science.gov (United States)

Craig, N.

2000-10-01

Sunspots is a web-based lesson that was developed by the Science Education Gateway (SEGway) program with participants from the Exploratorium, a well known science Museum in San Francisco, UC Berkeley Space Sciences Laboratory, and teachers from several California schools. This space science resource allows 8-12 grade students to explore the nature of sunspots and the history of solar physics in its effort to understand their nature. Interviews with solar physicists and archeo-astronomers, historic images, cutting-edge NASA images, movies, and research results, as well as a student-centered sunspot research activity using NASA space science data defines this lesson. The sunspot resource is aligned with the NCTM and National Science Education Standards. It emphasizes inquiry-based methods and mathematical exercises through measurement, graphic data representation, analysis of NASA data, lastly, interpreting results and drawing conclusions. These resources have been successfully classroom tested in 4 middle schools in the San Francisco Unified School District as part of the 3-week Summer School Science curricula. Lessons learned from the Summer School 1999 will be explained. This resource includes teacher-friendly lesson plans, space science background material and student worksheets. There will be Sunspots lesson CD-ROM and printed version of the relevant classroom-ready materials and a teacher resource booklet available. Sunspot resource is brought to you by, The Science Education Gateway - SEGway - Project, and the HESSI satellite and NASA's Office of Space Science Sun-Earth Connection Education Forum.

Improvement of the photometric sunspot index and changes of the disk-integrated sunspot contrast with time

Science.gov (United States)

Froehlich, Claus; Pap, Judit M.; Hudson, Hugh S.

1994-06-01

The photometric sunspot index (PSI) was developed to study the effects of sunspots on solar irradiance. It is calculated from the sunspot data published in the Solar-Geophysical Data catalog. It has been shown that the former PSI models overestimate the effect of dark sunspots on solar irradiance; furthermore results of direct sunspot photometry indicate that the contrast of spots depends on their area. An improved PSI calculation is presented; it takes into account the area dependence of the contrast and calculates `true' daily means for each observation using the differential rotation of the spots. Moreover, the observations are screened for outliers which improves the homogeneity of the data set substantially, at least for the period after December 1981 when NOAA started to report data from a few instead of one to two stations. A detailed description of the method is provided. The correlation between the newly calculated PSI and total solar irradiance is studied for different phases of the solar cycles 21 and 22 using bi-variate spectral analysis. The results can be used as a `calibration' of PSI in terms of gain, the factor by which PSI has to be multiplied to yield the observed irradiance change. The factor changes with time from about 0.6 in 1980 to 1.1 in 1990. This unexpected result cannot be interpreted by a change of the contrast relative to the quiet Sun (as it is normally defined and determined by direct photometry) but rather as a change of the contrast between the spots and their surrounding as seen in total irradiance (integrated over the solar disk). This may partly be explained by a change in the ratio between the areas of the spots and the surrounding faculae.

Holocene sea level, a semi-empirical contemplation

Science.gov (United States)

Bittermann, K.; Kemp, A.; Vermeer, M.; Rahmstorf, S.

2017-12-01

Holocene eustatic sea level from approximately -10,000-1800 CE was characterized by an increase of about 60m, with the rate progressively slowing down until sea level almost stabilizes between 500-1800 CE. Global and northern-hemisphere temperatures rose from the last glacial termination until the `Holocene Optimum'. From ­­there, up to the start of the recent anthropogenic rise, they almost steadily decline. How are the sea-level and temperature evolutions linked? We investigate this with semi-empirical sea-level models. We found that, due to the nature of Milankovitch forcing, northern-hemisphere temperature (we used the Greenland temperature by Vinther et al., 2009) is a better model driver than global mean temperature because the evolving mass of northern-hemisphere land ice was the dominant cause of Holocene global sea-level trends. The adjustment timescale for this contribution is 1200 years (900-1500 years; 90% confidence interval). To fit the observed sea-level history, the model requires a small additional constant rate (Bittermann 2016). This rate turns out to be of the same order of magnitude as reconstructions of Antarctic sea-level contributions (Briggs et al. 2014, Golledge et al. 2014). In reality this contribution is unlikely to be constant but rather has a dominant timescale that is large compared to the time considered. We thus propose that Holocene sea level can be described by a linear combination of a temperature driven rate, which becomes negative in the late Holocene (as Northern Hemisphere ice masses are diminished), and a positive, approximately constant term (possibly from Antarctica), which starts to dominate from the middle of the Holocene until the start of industrialization. Bibliography: Bittermann, K. 2016. Semi-empirical sea-level modelling. PhD Thesis University of Potsdam. Briggs, R.D., et al. 2014. A data-constrained large ensemble analysis of Antarctic evolution since the Eemian. Quaternary science reviews, 103, 91

The sunspot cycle revisited

International Nuclear Information System (INIS)

Lomb, Nick

2013-01-01

The set of sunspot numbers observed since the invention of the telescope is one of the most studied time series in astronomy and yet it is also one of the most complex. Fourteen frequencies are found in the yearly mean sunspot numbers from 1700 to 2011using the Lomb-Scargle periodogram and prewhitening. All of the frequencies corresponding to shorter term periods can be matched with simple algebraic combinations of the frequency of the main 11-year period and the frequencies of the longer term periods in the periodogram. This is exactly what can be expected from amplitude and phase modulation of an 11.12-year periodicity by longer term variations. Similar, though not identical, results are obtained after correcting the sunspot number series as proposed by Svalgaard. On looking separately at the amplitude and phase modulation a clear relationship is found between the two modulations although this relationship has broken down for the last four solar cycles. The phase modulation implies that there is a definite underlying period for the solar cycle. Such a clock mechanism does seem to be a possibility in models of the solar dynamo incorporating a conveyor-belt-like meridional circulation between high polar latitudes and the equator.

Nature's third cycle a story of sunspots

CERN Document Server

Choudhuri, Arnab Rai

2015-01-01

The cycle of day and night and the cycle of seasons are two familiar natural cycles around which many human activities are organized. But is there a third natural cycle of importance for us humans? On 13 March 1989, six million people in Canada went without electricity for many hours: a large explosion on the sun was discovered as the cause of this blackout. Such explosions occur above sunspots, dark features on the surface of the Sun that have been observed through telescopes since the time of Galileo. The number of sunspots has been found to wax and wane over a period of 11 years. Although this cycle was discovered less than two centuries ago, it is becoming increasingly important for us as human society becomes more dependent on technology. For nearly a century after its discovery, the cause of the sunspot cycle remained completely shrouded in mystery. The 1908 discovery of strong magnetic fields in sunspots made it clear that the 11-year cycle is the magnetic cycle of the sun. It is only during the last ...

Latitudinal migration of sunspots based on the ESAI database

Science.gov (United States)

Zhang, Juan; Li, Fu-Yu; Feng, Wen

2018-01-01

The latitudinal migration of sunspots toward the equator, which implies there is propagation of the toroidal magnetic flux wave at the base of the solar convection zone, is one of the crucial observational bases for the solar dynamo to generate a magnetic field by shearing of the pre-existing poloidal magnetic field through differential rotation. The Extended time series of Solar Activity Indices (ESAI) elongated the Greenwich observation record of sunspots by several decades in the past. In this study, ESAI’s yearly mean latitude of sunspots in the northern and southern hemispheres during the years 1854 to 1985 is utilized to statistically test whether hemispherical latitudinal migration of sunspots in a solar cycle is linear or nonlinear. It is found that a quadratic function is statistically significantly better at describing hemispherical latitudinal migration of sunspots in a solar cycle than a linear function. In addition, the latitude migration velocity of sunspots in a solar cycle decreases as the cycle progresses, providing a particular constraint for solar dynamo models. Indeed, the butterfly wing pattern with a faster latitudinal migration rate should present stronger solar activity with a shorter cycle period, and it is located at higher latitudinal position, giving evidence to support the Babcock-Leighton dynamo mechanism.

Situating and Constructing Diversity in Semi-Structured Interviews

Directory of Open Access Journals (Sweden)

Michele J. McIntosh

2015-08-01

Full Text Available Although semi-structured interviews (SSIs are used extensively in research, scant attention is given to their diversity, underlying assumptions, construction, and broad applications to qualitative and mixed-method research. In this three-part article, we discuss the following: (a how the SSI is situated historically including its evolution and diversification, (b the principles of constructing SSIs, and (c how SSIs are utilized as a stand-alone research method, and as strategy within a mixed-method design.

Interface of the polarizable continuum model of solvation with semi-empirical methods in the GAMESS program

DEFF Research Database (Denmark)

Svendsen, Casper Steinmann; Blædel, Kristoffer; Christensen, Anders S

2013-01-01

An interface between semi-empirical methods and the polarized continuum model (PCM) of solvation successfully implemented into GAMESS following the approach by Chudinov et al (Chem. Phys. 1992, 160, 41). The interface includes energy gradients and is parallelized. For large molecules such as ubiq......An interface between semi-empirical methods and the polarized continuum model (PCM) of solvation successfully implemented into GAMESS following the approach by Chudinov et al (Chem. Phys. 1992, 160, 41). The interface includes energy gradients and is parallelized. For large molecules...... such as ubiquitin a reasonable speedup (up to a factor of six) is observed for up to 16 cores. The SCF convergence is greatly improved by PCM for proteins compared to the gas phase....

Semi-empirical evaluation studies on PCMI for the Fugen fuel rod

International Nuclear Information System (INIS)

Domoto, Kazushige; Kaneko, Mitsunobu; Takeuchi, Kiyoshi.

1980-03-01

Fugen, 165 MWe prototype of a heavy water moderated boiling water cooled reactor, has been well operated since March 1979. In order to establish PCIOMR for Fugen fuels semi-empirical evaluation code to analyze PCMI during power transient of the fuel rod has been developed. In this paper, followings are described 1) general scope of the development work 2) description of the modelling 3) some results of analysis on out pile and in pile tests. (author)

A Standard Law for the Equatorward Drift of the Sunspot Zones

Science.gov (United States)

Hathaway, David H.

2012-01-01

The latitudinal location of the sunspot zones in each hemisphere is determined by calculating the centroid position of sunspot areas for each solar rotation from May 1874 to June 2012. When these centroid positions are plotted and analyzed as functions of time from each sunspot cycle maximum there appears to be systematic differences in the positions and equatorward drift rates as a function of sunspot cycle amplitude. If, instead, these centroid positions are plotted and analyzed as functions of time from each sunspot cycle minimum then most of the differences in the positions and equatorward drift rates disappear. The differences that remain disappear entirely if curve fitting is used to determine the starting times (which vary by as much as 8 months from the times of minima). The sunspot zone latitudes and equatorward drift measured relative to this starting time follow a standard path for all cycles with no dependence upon cycle strength or hemispheric dominance. Although Cycle 23 was peculiar in its length and the strength of the polar fields it produced, it too shows no significant variation from this standard. This standard law, and the lack of variation with sunspot cycle characteristics, is consistent with Dynamo Wave mechanisms but not consistent with current Flux Transport Dynamo models for the equatorward drift of the sunspot zones.

Comparison of a semi-empirical method with some model codes for gamma-ray spectrum calculation

Energy Technology Data Exchange (ETDEWEB)

Sheng, Fan; Zhixiang, Zhao [Chinese Nuclear Data Center, Beijing, BJ (China)

1996-06-01

Gamma-ray spectra calculated by a semi-empirical method are compared with those calculated by the model codes such as GNASH, TNG, UNF and NDCP-1. The results of the calculations are discussed. (2 tabs., 3 figs.).

A semi-empirical analysis of strong-motion peaks in terms of seismic source, propagation path, and local site conditions

Science.gov (United States)

Kamiyama, M.; Orourke, M. J.; Flores-Berrones, R.

1992-09-01

A new type of semi-empirical expression for scaling strong-motion peaks in terms of seismic source, propagation path, and local site conditions is derived. Peak acceleration, peak velocity, and peak displacement are analyzed in a similar fashion because they are interrelated. However, emphasis is placed on the peak velocity which is a key ground motion parameter for lifeline earthquake engineering studies. With the help of seismic source theories, the semi-empirical model is derived using strong motions obtained in Japan. In the derivation, statistical considerations are used in the selection of the model itself and the model parameters. Earthquake magnitude M and hypocentral distance r are selected as independent variables and the dummy variables are introduced to identify the amplification factor due to individual local site conditions. The resulting semi-empirical expressions for the peak acceleration, velocity, and displacement are then compared with strong-motion data observed during three earthquakes in the U.S. and Mexico.

Long-term Modulation of Cosmic Ray Intensity in relation to Sunspot ...

Indian Academy of Sciences (India)

it should be more closely connected with cosmic ray modulation than with other solar characteristics (sunspot numbers or coronal emission intensity). The intensity of galactic cosmic rays varies inversely with sunspot numbers, having their maximum intensity at the minimum of the 11-year sunspot cycle (Forbush 1954, 1958) ...

The Flares Associated with the Dynamics of the Sunspots K. M. ...

Indian Academy of Sciences (India)

tional theory of magnetic reconnection is briefly discussed. ... between changes in the sunspots' dynamics, emerging flux region, twisting of the field ... the eventual triggering of the flares is due to proper motion of the sunspots. Using .... rotation rates obtained from the daily motion of sunspot groups with respect to their life.

Experimental and semi-empirical and DFT calculational studies on (E)-2-((2-morpholinoethyliminio)methyl)-4-nitrophenolate

International Nuclear Information System (INIS)

Alpaslan, Y. B.; Agar, E.; Ersahin, F.; Iskeleli, N. O.; Oeztekin, E.

2010-01-01

The molecular and crystal structure of the title compound, C 1 3H 1 7N 3 O 4 , has been determined by X-ray single crystal diffraction technique. The compound crystallizes in the triclinic, space group P-1 with unit cell dimensions a=5.3520(4), b=10.9011(8), c=12.4537(9)A 0 , Mr=279.30, V=675.91(9)A 03 , Z=2, R1=0.037 and wR 2 =0.097. The molecule adopts a zwitterionic form, stabilized by an intramolecular N + -H 2 O- type ionic weak hydrogen bond. The molecule pack via intermolecular N-H 2 O hydrogen bonds which, together with an intramolecular N + -H 2 O- bond. Calculational studies were performed by using AM1, PM3, semi-empirical and DFT methods. Geometry optimizations of compound have been carried out by using three semi-empirical methods and DFT method and bond lengths, bond and torsion angles of title compound have been determined. Atomic charge distribution have been obtained from DFT. In order to determine conformational flexibility on the molecule, molecular energy profile of the title compound was obtained with respect to the selected torsion angle T(C2-C1-C7-N1), which is varied from -180 0 degree to +180 0 degree in every 10 via PM3 semi-empirical method.

Sunspot splitting triggering an eruptive flare

Science.gov (United States)

Louis, Rohan E.; Puschmann, Klaus G.; Kliem, Bernhard; Balthasar, Horst; Denker, Carsten

2014-02-01

Aims: We investigate how the splitting of the leading sunspot and associated flux emergence and cancellation in active region NOAA 11515 caused an eruptive M5.6 flare on 2012 July 2. Methods: Continuum intensity, line-of-sight magnetogram, and dopplergram data of the Helioseismic and Magnetic Imager were employed to analyse the photospheric evolution. Filtergrams in Hα and He I 10830 Å of the Chromospheric Telescope at the Observatorio del Teide, Tenerife, track the evolution of the flare. The corresponding coronal conditions were derived from 171 Å and 304 Å images of the Atmospheric Imaging Assembly. Local correlation tracking was utilized to determine shear flows. Results: Emerging flux formed a neutral line ahead of the leading sunspot and new satellite spots. The sunspot splitting caused a long-lasting flow towards this neutral line, where a filament formed. Further flux emergence, partly of mixed polarity, as well as episodes of flux cancellation occurred repeatedly at the neutral line. Following a nearby C-class precursor flare with signs of interaction with the filament, the filament erupted nearly simultaneously with the onset of the M5.6 flare and evolved into a coronal mass ejection. The sunspot stretched without forming a light bridge, splitting unusually fast (within about a day, complete ≈6 h after the eruption) in two nearly equal parts. The front part separated strongly from the active region to approach the neighbouring active region where all its coronal magnetic connections were rooted. It also rotated rapidly (by 4.9° h-1) and caused significant shear flows at its edge. Conclusions: The eruption resulted from a complex sequence of processes in the (sub-)photosphere and corona. The persistent flows towards the neutral line likely caused the formation of a flux rope that held the filament. These flows, their associated flux cancellation, the emerging flux, and the precursor flare all contributed to the destabilization of the flux rope. We

SEISMIC DISCRIMINATION OF THERMAL AND MAGNETIC ANOMALIES IN SUNSPOT UMBRAE

International Nuclear Information System (INIS)

Lindsey, C.; Cally, P. S.; Rempel, M.

2010-01-01

Efforts to model sunspots based on helioseismic signatures need to discriminate between the effects of (1) a strong magnetic field that introduces time-irreversible, vantage-dependent phase shifts, apparently connected to fast- and slow-mode coupling and wave absorption and (2) a thermal anomaly that includes cool gas extending an indefinite depth beneath the photosphere. Helioseismic observations of sunspots show travel times considerably reduced with respect to equivalent quiet-Sun signatures. Simulations by Moradi and Cally of waves skipping across sunspots with photospheric magnetic fields of order 3 kG show travel times that respond strongly to the magnetic field and relatively weakly to the thermal anomaly by itself. We note that waves propagating vertically in a vertical magnetic field are relatively insensitive to the magnetic field, while remaining highly responsive to the attendant thermal anomaly. Travel-time measurements for waves with large skip distances into the centers of axially symmetric sunspots are therefore a crucial resource for discrimination of the thermal anomaly beneath sunspot umbrae from the magnetic anomaly. One-dimensional models of sunspot umbrae based on compressible-radiative-magnetic-convective simulations such as by Rempel et al. can be fashioned to fit observed helioseismic travel-time spectra in the centers of sunspot umbrae. These models are based on cooling of the upper 2-4 Mm of the umbral subphotosphere with no significant anomaly beneath 4.5 Mm. The travel-time reductions characteristic of these models are primarily a consequence of a Wilson depression resulting from a strong downward buoyancy of the cooled umbral medium.

Applicability of special quasi-random structure models in thermodynamic calculations using semi-empirical Debye–Grüneisen theory

International Nuclear Information System (INIS)

Kim, Jiwoong

2015-01-01

In theoretical calculations, expressing the random distribution of atoms in a certain crystal structure is still challenging. The special quasi-random structure (SQS) model is effective for depicting such random distributions. The SQS model has not been applied to semi-empirical thermodynamic calculations; however, Debye–Grüneisen theory (DGT), a semi-empirical method, was used here for that purpose. The model reliability was obtained by comparing supercell models of various sizes. The results for chemical bonds, pair correlation, and elastic properties demonstrated the reliability of the SQS models. Thermodynamic calculations using density functional perturbation theory (DFPT) and DGT assessed the applicability of the SQS models. DGT and DFPT led to similar variations of the mixing and formation energies. This study provides guidelines for theoretical assessments to obtain the reliable SQS models and to calculate the thermodynamic properties of numerous materials with a random atomic distribution. - Highlights: • Various material properties are used to examine reliability of special quasi-random structures. • SQS models are applied to thermodynamic calculations by semi-empirical methods. • Basic calculation guidelines for materials with random atomic distribution are given.

Towards a first detailed reconstruction of sunspot information over the last 150 years

Science.gov (United States)

Lefevre, Laure; Clette, Frédéric

2013-04-01

With four centuries of solar evolution, the International Sunspot Number (SSN) forms the longest solar time series currently available. It provides an essential reference for understanding and quantifying how the solar output has varied over decades and centuries and thus for assessing the variations of the main natural forcing on the Earth climate. For such a quantitative use, this unique time-series must be closely monitored for any possible biases and drifts. This is the main objective of the Sunspot Workshops organized jointly by the National Solar Observatory (NSO) and the Royal Observatory of Belgium (ROB) since 2010. Here, we will report about some recent outcomes of past workshops, like diagnostics of scaling errors and their proposed corrections, or the recent disagreement between the sunspot sumber and other solar indices like the 10.7cm radio flux. Our most recent analyses indicate that while part of this divergence may be due to a calibration drift in the SSN, it also results from an intrinsic change in the global magnetic parameters of sunspots and solar active regions, suggesting a possible transition to a new activity regime. Going beyond the SSN series, in the framework of the SOTERIA, TOSCA and SOLID projects, we produced a survey of all existing catalogs providing detailed sunspot information and we also located different primary solar images and drawing collections that can be exploitable to complement the existing catalogs (COMESEP project). These are first steps towards the construction of a multi-parametric time series of multiple sunspot group properties over at least the last 150 years, allowing to reconstruct and extend the current 1-D SSN series. By bringing new spatial, morphological and evolutionary information, such a data set should bring major advances for the modeling of the solar dynamo and solar irradiance. We will present here the current status of this work. The catalog now extends over the last 3 cycles (Lefevre & Clette 2011

Aircraft directional stability and vertical tail design: A review of semi-empirical methods

Science.gov (United States)

Ciliberti, Danilo; Della Vecchia, Pierluigi; Nicolosi, Fabrizio; De Marco, Agostino

2017-11-01

Aircraft directional stability and control are related to vertical tail design. The safety, performance, and flight qualities of an aircraft also depend on a correct empennage sizing. Specifically, the vertical tail is responsible for the aircraft yaw stability and control. If these characteristics are not well balanced, the entire aircraft design may fail. Stability and control are often evaluated, especially in the preliminary design phase, with semi-empirical methods, which are based on the results of experimental investigations performed in the past decades, and occasionally are merged with data provided by theoretical assumptions. This paper reviews the standard semi-empirical methods usually applied in the estimation of airplane directional stability derivatives in preliminary design, highlighting the advantages and drawbacks of these approaches that were developed from wind tunnel tests performed mainly on fighter airplane configurations of the first decades of the past century, and discussing their applicability on current transport aircraft configurations. Recent investigations made by the authors have shown the limit of these methods, proving the existence of aerodynamic interference effects in sideslip conditions which are not adequately considered in classical formulations. The article continues with a concise review of the numerical methods for aerodynamics and their applicability in aircraft design, highlighting how Reynolds-Averaged Navier-Stokes (RANS) solvers are well-suited to attain reliable results in attached flow conditions, with reasonable computational times. From the results of RANS simulations on a modular model of a representative regional turboprop airplane layout, the authors have developed a modern method to evaluate the vertical tail and fuselage contributions to aircraft directional stability. The investigation on the modular model has permitted an effective analysis of the aerodynamic interference effects by moving, changing, and

Sunspot Oscillations From The Chromosphere To The Corona

Science.gov (United States)

Brynildsen, N.; Maltby, P.; Fredvik, T.; Kjeldseth-Moe, O.

The behavior of the 3 minute sunspot oscillations is studied as a function of temper- ature through the transition region using observations with CDS/SOHO and TRACE. The oscillations occur above the umbra, with amplitudes increasing to a maximum near 200 000 K, then decreasing towards higher temperatures. Deviations from pure linear oscillations are present in several cases. Power spectra of the oscillations are remarkably similar in the chromosphere and through the transition region in contra- diction to the predictions of the sunspot filter theory. The 3 minute oscillations pene- trate to the low temperature end of the corona, where they are channeled into smaller areas coinciding with the endpoints of sunspot coronal loops. This differs from the transition zone where the oscillating region covers the umbra.

Interactions between nested sunspots. 1: The formation and breakup of a delta-type sunspot

Science.gov (United States)

Gaizauskas, V.; Harvey, K. L.; Proulx, M.

1994-01-01

We investigate a nest of sunspots in which three ordinary bipolar pairs of sunspots are aligned collinearly. The usual spreading action of the growing regions brings two spots of leading polarity together (p-p collision) and forces the leading and trailing spots of the two interior regions to overlap inot a single penumbra (p-f collision), thus forming a delta-spot. We examine digitally processed images from the Ottawa River Solar Observatory of two related events inside the delta-spot 5 days after the p-f collision begins: the violent disruption of the f-umbra, and the formation in less than a day of an hydrogen-alpha filament. The evolutionary changes in shape, area, relative motions, and brightness that we measure for each spot in the elongated nest are more compatible with Parker's (1979a) hypothesis of a sunspot as a cluster of flux tubes held together by downdrafts than with the notion of a sunspot as a monolithic plug of magnetic flux. From chromospheric developments over the delta-spot, we show that a shearing motion along a polarity inversion is more effective than convergence for creating a chromospheric filament. We invoke the release of an instability, triggered by a sequence of processes lasting 1 day or more, to explain the disruption of the f-umbra in this delta-spot. We show that the sequence is initiated when the colliding p-f umbrae reach a critical separation around 3200 +/- 200 km. We present a descriptive model in which the reconnected magnetic fields block vertical transport of convective heat flux just beneath the photosphere. We observe the formation of an unusual type of penumbra adjacent to the f-polarity portion of this delta-spot just before its disruption. A tangential penumbral band grows out of disordered matter connected to the f-umbra. We present this as evidence for the extrusion of umbral magnetic flux by thermal plumes rising through a loosely bound umbra.

An Improved Semi-Empirical Model for Radar Backscattering from Rough Sea Surfaces at X-Band

Directory of Open Access Journals (Sweden)

Taekyeong Jin

2018-04-01

Full Text Available We propose an improved semi-empirical scattering model for X-band radar backscattering from rough sea surfaces. This new model has a wider validity range of wind speeds than does the existing semi-empirical sea spectrum (SESS model. First, we retrieved the small-roughness parameters from the sea surfaces, which were numerically generated using the Pierson-Moskowitz spectrum and measurement datasets for various wind speeds. Then, we computed the backscattering coefficients of the small-roughness surfaces for various wind speeds using the integral equation method model. Finally, the large-roughness characteristics were taken into account by integrating the small-roughness backscattering coefficients multiplying them with the surface slope probability density function for all possible surface slopes. The new model includes a wind speed range below 3.46 m/s, which was not covered by the existing SESS model. The accuracy of the new model was verified with two measurement datasets for various wind speeds from 0.5 m/s to 14 m/s.

Newly developed semi-empirical formulas for (p, α) at 17.9 MeV and ...

Indian Academy of Sciences (India)

Home; Journals; Pramana – Journal of Physics; Volume 74; Issue 6. Newly developed semi-empirical formulas for (, ) at 17.9 MeV and (, ) at 22.3 MeV reaction cross-sections. Eyyup Tel Abdullah Aydin E Gamze Aydin Abdullah Kaplan Ömer Yavaş İskender A Reyhancan. Research Articles Volume 74 Issue 6 June ...

Observational Evidence of a Flux Rope within a Sunspot Umbra

Energy Technology Data Exchange (ETDEWEB)

Guglielmino, Salvo L.; Zuccarello, Francesca [Dipartimento di Fisica e Astronomia—Sezione Astrofisica, Università di Catania, Via S. Sofia 78, I-95125 Catania (Italy); Romano, Paolo, E-mail: salvo.guglielmino@oact.inaf.it [INAF—Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95125 Catania (Italy)

2017-09-10

We observed an elongated filamentary bright structure inside the umbra of the big sunspot in active region NOAA 12529, which differs from the light bridges usually observed in sunspots for its morphology, magnetic configuration, and velocity field. We used observations taken with the Solar Dynamic Observatory satellite to characterize this feature. Its lifetime is 5 days, during which it reaches a maximum length of about 30″. In the maps of the vertical component of the photospheric magnetic field, a portion of the feature has a polarity opposite to that of the hosting sunspot. At the same time, in the entire feature the horizontal component of the magnetic field is about 2000 G, substantially stronger than in the surrounding penumbral filaments. Doppler velocity maps reveal the presence of both upward and downward plasma motions along the structure at the photospheric level. Moreover, looking at the chromospheric level, we noted that it is located in a region corresponding to the edge of a small filament that seems rooted in the sunspot umbra. Therefore, we interpreted the bright structure as the photospheric counterpart of a flux rope touching the sunspot and giving rise to penumbral-like filaments in the umbra.

Application of Avco data analysis and prediction techniques (ADAPT) to prediction of sunspot activity

Science.gov (United States)

Hunter, H. E.; Amato, R. A.

1972-01-01

The results are presented of the application of Avco Data Analysis and Prediction Techniques (ADAPT) to derivation of new algorithms for the prediction of future sunspot activity. The ADAPT derived algorithms show a factor of 2 to 3 reduction in the expected 2-sigma errors in the estimates of the 81-day running average of the Zurich sunspot numbers. The report presents: (1) the best estimates for sunspot cycles 20 and 21, (2) a comparison of the ADAPT performance with conventional techniques, and (3) specific approaches to further reduction in the errors of estimated sunspot activity and to recovery of earlier sunspot historical data. The ADAPT programs are used both to derive regression algorithm for prediction of the entire 11-year sunspot cycle from the preceding two cycles and to derive extrapolation algorithms for extrapolating a given sunspot cycle based on any available portion of the cycle.

Semi-empirical neural network models of controlled dynamical systems

Directory of Open Access Journals (Sweden)

Mihail V. Egorchev

2017-12-01

Full Text Available A simulation approach is discussed for maneuverable aircraft motion as nonlinear controlled dynamical system under multiple and diverse uncertainties including knowledge imperfection concerning simulated plant and its environment exposure. The suggested approach is based on a merging of theoretical knowledge for the plant with training tools of artificial neural network field. The efficiency of this approach is demonstrated using the example of motion modeling and the identification of the aerodynamic characteristics of a maneuverable aircraft. A semi-empirical recurrent neural network based model learning algorithm is proposed for multi-step ahead prediction problem. This algorithm sequentially states and solves numerical optimization subproblems of increasing complexity, using each solution as initial guess for subsequent subproblem. We also consider a procedure for representative training set acquisition that utilizes multisine control signals.

Semi-empirical quantum evaluation of peptide - MHC class II binding

Science.gov (United States)

González, Ronald; Suárez, Carlos F.; Bohórquez, Hugo J.; Patarroyo, Manuel A.; Patarroyo, Manuel E.

2017-01-01

Peptide presentation by the major histocompatibility complex (MHC) is a key process for triggering a specific immune response. Studying peptide-MHC (pMHC) binding from a structural-based approach has potential for reducing the costs of investigation into vaccine development. This study involved using two semi-empirical quantum chemistry methods (PM7 and FMO-DFTB) for computing the binding energies of peptides bonded to HLA-DR1 and HLA-DR2. We found that key stabilising water molecules involved in the peptide binding mechanism were required for finding high correlation with IC50 experimental values. Our proposal is computationally non-intensive, and is a reliable alternative for studying pMHC binding interactions.

The Recalibrated Sunspot Number: Impact on Solar Cycle Predictions

Science.gov (United States)

Clette, F.; Lefevre, L.

2017-12-01

Recently and for the first time since their creation, the sunspot number and group number series were entirely revisited and a first fully recalibrated version was officially released in July 2015 by the World Data Center SILSO (Brussels). Those reference long-term series are widely used as input data or as a calibration reference by various solar cycle prediction methods. Therefore, past predictions may now need to be redone using the new sunspot series, and methods already used for predicting cycle 24 will require adaptations before attempting predictions of the next cycles.In order to clarify the nature of the applied changes, we describe the different corrections applied to the sunspot and group number series, which affect extended time periods and can reach up to 40%. While some changes simply involve constant scale factors, other corrections vary with time or follow the solar cycle modulation. Depending on the prediction method and on the selected time interval, this can lead to different responses and biases. Moreover, together with the new series, standard error estimates are also progressively added to the new sunspot numbers, which may help deriving more accurate uncertainties for predicted activity indices. We conclude on the new round of recalibration that is now undertaken in the framework of a broad multi-team collaboration articulated around upcoming ISSI workshops. We outline the future corrections that can still be expected in the future, as part of a permanent upgrading process and quality control. From now on, future sunspot-based predictive models should thus be made more adaptable, and regular updates of predictions should become common practice in order to track periodic upgrades of the sunspot number series, just like it is done when using other modern solar observational series.

The EUV Spectrum of Sunspot Plumes Observed by SUMER on ...

Indian Academy of Sciences (India)

tribpo

Abstract. We present results from sunspot observations obtained by. SUMER on SOHO. In sunspot plumes the EUV spectrum differs from the quiet Sun; continua are observed with different slopes and intensities; emission lines from molecular hydrogen and many unidentified species indicate unique plasma conditions ...

Assessment of semi-empirical potentials for the U-Si system

Energy Technology Data Exchange (ETDEWEB)

Baskes, Michael I. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Andersson, Anders David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-02-03

Accident tolerant fuels (ATF) are being developed in response to the Fukushima Daiichi accident in Japan. One of the options being pursued is U-Si fuels, such as the U₃Si₂ and U₃Si₅ compounds, which benefit from high thermal conductivity (metallic) compared to the UO2 fuel (semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for U-Si fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap. Even though Density Functional Theory (DFT) calculations can provide useful answers to a subset of problems, they are computationally too costly for many others, including properties governing microstructure evolution and irradiation effects. For the latter, semi-empirical potentials are typically used. Unfortunately, there is currently no potential for the U-Si system. In this brief report we present initial results from the development of a U-Si semi-empirical potential based on the Modified Embedded Atom Method (MEAM). The potential should reproduce relevant parts of the U-Si phase diagram as well as defect properties important in irradiation environments. This work also serves as an assessment of the general challenges associated with the U-Si system, which will be valuable for the efforts to develop a U-Si Tersoff potential undertaken by Idaho National Laboratory (also part of the ATF HIP). Going forward the main potential development activity will reside at INL and the work presented here is meant to provide input data and guidelines for that activity. The main focus of our work is on the U₃Si₂ and U3Si₅

A new look at sunspot formation using theory and observations

Science.gov (United States)

Losada, I. R.; Warnecke, J.; Glogowski, K.; Roth, M.; Brandenburg, A.; Kleeorin, N.; Rogachevskii, I.

2017-10-01

Sunspots are of basic interest in the study of the Sun. Their relevance ranges from them being an activity indicator of magnetic fields to being the place where coronal mass ejections and flares erupt. They are therefore also an important ingredient of space weather. Their formation, however, is still an unresolved problem in solar physics. Observations utilize just 2D surface information near the spot, but it is debatable how to infer deep structures and properties from local helioseismology. For a long time, it was believed that flux tubes rising from the bottom of the convection zone are the origin of the bipolar sunspot structure seen on the solar surface. However, this theory has been challenged, in particular recently by new surface observation, helioseismic inversions, and numerical models of convective dynamos. In this article we discuss another theoretical approach to the formation of sunspots: the negative effective magnetic pressure instability. This is a large-scale instability, in which the total (kinetic plus magnetic) turbulent pressure can be suppressed in the presence of a weak large-scale magnetic field, leading to a converging downflow, which eventually concentrates the magnetic field within it. Numerical simulations of forced stratified turbulence have been able to produce strong super-equipartition flux concentrations, similar to sunspots at the solar surface. In this framework, sunspots would only form close to the surface due to the instability constraints on stratification and rotation. Additionally, we present some ideas from local helioseismology, where we plan to use the Hankel analysis to study the pre-emergence phase of a sunspot and to constrain its deep structure and formation mechanism.

Empirical solar/stellar cycle simulations

Directory of Open Access Journals (Sweden)

Santos Ângela R. G.

2015-01-01

Full Text Available As a result of the magnetic cycle, the properties of the solar oscillations vary periodically. With the recent discovery of manifestations of activity cycles in the seismic data of other stars, the understanding of the different contributions to such variations becomes even more important. With this in mind, we built an empirical parameterised model able to reproduce the properties of the sunspot cycle. The resulting simulations can be used to estimate the magnetic-induced frequency shifts.

Modelling of proton exchange membrane fuel cell performance based on semi-empirical equations

Energy Technology Data Exchange (ETDEWEB)

Al-Baghdadi, Maher A.R. Sadiq [Babylon Univ., Dept. of Mechanical Engineering, Babylon (Iraq)

2005-08-01

Using semi-empirical equations for modeling a proton exchange membrane fuel cell is proposed for providing a tool for the design and analysis of fuel cell total systems. The focus of this study is to derive an empirical model including process variations to estimate the performance of fuel cell without extensive calculations. The model take into account not only the current density but also the process variations, such as the gas pressure, temperature, humidity, and utilization to cover operating processes, which are important factors in determining the real performance of fuel cell. The modelling results are compared well with known experimental results. The comparison shows good agreements between the modeling results and the experimental data. The model can be used to investigate the influence of process variables for design optimization of fuel cells, stacks, and complete fuel cell power system. (Author)

Investigation of Quasi-periodic Solar Oscillations in Sunspots Based on SOHO/MDI Magnetograms

Science.gov (United States)

Kallunki, J.; Riehokainen, A.

2012-10-01

In this work we study quasi-periodic solar oscillations in sunspots, based on the variation of the amplitude of the magnetic field strength and the variation of the sunspot area. We investigate long-period oscillations between three minutes and ten hours. The magnetic field synoptic maps were obtained from the SOHO/MDI. Wavelet (Morlet), global wavelet spectrum (GWS) and fast Fourier transform (FFT) methods are used in the periodicity analysis at the 95 % significance level. Additionally, the quiet Sun area (QSA) signal and an instrumental effect are discussed. We find several oscillation periods in the sunspots above the 95 % significance level: 3 - 5, 10 - 23, 220 - 240, 340 and 470 minutes, and we also find common oscillation periods (10 - 23 minutes) between the sunspot area variation and that of the magnetic field strength. We discuss possible mechanisms for the obtained results, based on the existing models for sunspot oscillations.

Experimental and semi-empirical and DFT calculational studies on (e)-2-(1-(2-(4-methylphenylsulfonamido) ethyliminio) ethyl) phenolate

International Nuclear Information System (INIS)

Alpaslan, G.; Agar, E.; Ersahin, F.; Isik, S.; Erdoenmez, A.

2010-01-01

The molecular and crystal structure of the title compound, C 1 7H 2 0N 2 O 3 S, has been determined by X-ray single crystal diffraction technique. The compound crystallizes in the monoclinic, space group P2 1 /n with unit cell dimensions a=11.4472(6), b=11.1176(4), c=13.4873(7)A 0 , M r =332.41, V=1639.36(13)A 03 , Z=4, R 1 =0.034 and wR 2 =0.097. The molecule adopts a zwitterionic form, stabilized by an intramolecular N + -H 2 O - type ionic weak hydrogen bond. The molecule pack via intermolecular N-H 2 O hydrogen bonds which, together with an intramolecular N + -H 2 O - bond, form an S(6)R 2 4 (4)S(6) motif. Calculational studies were performed by using AM1, PM3 semi-empirical and DFT methods. Geometry optimizations of compound have been carried out by using three semi-empirical methods and DFT method and bond lengths, bond and torsion angles of title compound have been determined. Atomic charge distribution have been obtained from AM1, PM3 and DFT. In order to determine conformational flexibility on the molecule, molecular energy profile of the title compound was obtained with respect to the selected torsion angle T(N1-C9-C10-N2), which is varied from -180 degrees to +180 degrees in every 10 via PM3 semi-empirical method.

Photoelectric observations of propagating sunspot oscillations

International Nuclear Information System (INIS)

Lites, B.W.; White, O.R.; Packman, D.

1982-01-01

The Sacramento Park Observatory Vacuum Tower Telescope and diode array were used to make repeated intensity and velocity images of a large, isolated sunspot in both a chromospheric (lambda8542 Ca II) and a photospheric (lambda5576 Fe I) line. The movie of the digital data for the chromospheric line shows clearly a relationship between the propagating umbral disturbances and the running penumbral waves. The velocities for transverse propagating of the umbral and penumbral disturbances are 60--70 km s -1 and 20--35 km s -1 , respectively. Power spectra of the oscillations show a sharp peak at a period of about 170 s in both the velocity and intensity signals. The rms velocity fluctuation of this power peak is 0.26 km s -1 . The oscillations at any given point in the sunspot are very regular, and the phase relationship between the velocity and intensity of the chromospheric oscillations is radically different than that for the quiet Sun. Our preliminary interpretation of the phase relationship involves acoustic waves with wave vector directed downwards along the magnetic field lines; however, this interpretation relies on assumptions involved in the data reduction scheme. The mechanical energy flux carried by the observed umbral disturbances does not appear to be a significant contributor to the overall energy budget of the sunspot or the surrounding active region

On the chromospheric network structure around deVeloped groups of sunspots

International Nuclear Information System (INIS)

Kartashova, L.G.

1980-01-01

The chromospheric network structure around several developed groups of sunspots were studied on the basis of the observations in the Hsub(α) line. The resolution on the filtergrams was of 2. The following was found: 1) in the neighbourhood of the groups of sunspots 70% (from 870) of network cells stretch along fibrils direction (with accuracy 30 deg), and 15% of cells stretch approximately across that (at angles 70-90 deg); 2) out of the boundary of the main radial fibrils structure the groups of sunspots is often rounded by the system of network cells stretched approximately perpendicular to radial direction

The photospheric vector magnetic field of a sunspot and its vertical gradient

Science.gov (United States)

Hagyard, M. J.; West, E. A.; Tandberg-Hanssen, E.; Smith, J. E.; Henze, W., Jr.; Beckers, J. M.; Bruner, E. C.; Hyder, C. L.; Gurman, J. B.; Shine, R. A.

1981-01-01

The results of direct comparisons of photospheric and transition region line-of-sight field observations of sunspots using the SMM UV spectrometer and polarimeter are reported. The analysis accompanying the data is concentrated on demonstrating that the sunspot concentrated magnetic field extends into the transition region. An observation of a sunspot on Oct. 23, 1980 at the S 18 E 03 location is used as an example. Maximum field strengths ranged from 2030-2240 gauss for large and small umbrae viewed and inclination of the field to the line-of-sight was determined for the photosphere and transition region. The distribution of the magnetic field over the sunspot and variation of the line-of-sight gradient are discussed, as are the magnitudes and gradients of the photospheric field across the penumbral-photospheric boundaries.

The visibility function and its effect on the observed characteristics of sunspot groups. 1

International Nuclear Information System (INIS)

Kopecky, M.; Kuklin, G.V.; Starkova, I.P.

1985-01-01

The paper is an introductory study to a series dealing with the visibility function, the function of foreshortening of sunspot group areas, and with the effect of these functions on the results of the statistical processing of observations, which has to be taken into account in interpreting the results. A ''diagram of observational conditions'' is described, which enables a number of statistical problems of sunspot groups on the rotating Sun to be solved by computer modelling or by graphical methods. Examples are given of the use of this diagram in studying the distribution of the observed lifetime of sunspot groups with a given actual lifetime, of the decrease in the number of sunspot groups towards the limb of the solar disc, of the east-west asymmetry of sunspot group appearance and disappearance. (author)

A semi-empirical formula on the pre-neutron-emission fragment mass distribution in nuclear fission

International Nuclear Information System (INIS)

Wang Fucheng; Hu Jimin

1988-03-01

A 5-Gauss semi-empirical formula on the pre-neutron-emission fragment mass distribution is given. The absolute standard deviation and maximum departure between calculated values and experimental data for (n,f) and (n,n'f) fission reactions from 232 Th to 245 Cm are approximately 0.4% and 0.8%, respectively. The error will get bigger if the formula is used at higher excitation energies

Vertical gradients of sunspot magnetic fields

Science.gov (United States)

Hagyard, M. J.; Teuber, D.; West, E. A.; Tandberg-Hanssen, E.; Henze, W., Jr.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; Woodgate, B. E.

1983-01-01

The results of a Solar Maximum Mission (SMM) guest investigation to determine the vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields are described. Descriptions are given of both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight Center vector magnetograph, and of the line-of-sight component in the transition region, obtained from the SMM Ultraviolet Spectrometer and Polarimeter instrument. On the basis of these data, vertical gradients of the line-of-sight magnetic field component are calculated using three methods. It is found that the vertical gradient of Bz is lower than values from previous studies and that the transition-region field occurs at a height of approximately 4000-6000 km above the photosphere.

Sunspot Equilibria in a Production Economy: Do Rational Animal Spirits Cause Overproduction?

OpenAIRE

Kajii, Atsushi

2008-01-01

We study a standard two period economy with one nominal bond and one firm. The input of the firm is done in the first period and financed with the nominal bond, and its profits are distributed to the shareholders in the second period. We show that a sunspot equilibrium exists around each efficient equilibrium. The interest rate is lower than optimal and there is over production in sunspot equilibria, under some conditions. But a sunspot equilibrium does not exist if the profit share can be tr...

Prediction on sunspot activity based on fuzzy information granulation and support vector machine

Science.gov (United States)

Peng, Lingling; Yan, Haisheng; Yang, Zhigang

2018-04-01

In order to analyze the range of sunspots, a combined prediction method of forecasting the fluctuation range of sunspots based on fuzzy information granulation (FIG) and support vector machine (SVM) was put forward. Firstly, employing the FIG to granulate sample data and extract va)alid information of each window, namely the minimum value, the general average value and the maximum value of each window. Secondly, forecasting model is built respectively with SVM and then cross method is used to optimize these parameters. Finally, the fluctuation range of sunspots is forecasted with the optimized SVM model. Case study demonstrates that the model have high accuracy and can effectively predict the fluctuation of sunspots.

Development and empirical validation of symmetric component measures of multi-dimensional constructs

DEFF Research Database (Denmark)

Sørensen, Hans Eibe; Slater, Stanley F.

2008-01-01

Atheoretical measure purification may lead to construct deficient measures. The purpose of this paper is to provide a theoretically driven procedure for the development and empirical validation of symmetric component measures of multi-dimensional constructs. We place particular emphasis on establ...

Semi-empirical master curve concept describing the rate capability of lithium insertion electrodes

Science.gov (United States)

Heubner, C.; Seeba, J.; Liebmann, T.; Nickol, A.; Börner, S.; Fritsch, M.; Nikolowski, K.; Wolter, M.; Schneider, M.; Michaelis, A.

2018-03-01

A simple semi-empirical master curve concept, describing the rate capability of porous insertion electrodes for lithium-ion batteries, is proposed. The model is based on the evaluation of the time constants of lithium diffusion in the liquid electrolyte and the solid active material. This theoretical approach is successfully verified by comprehensive experimental investigations of the rate capability of a large number of porous insertion electrodes with various active materials and design parameters. It turns out, that the rate capability of all investigated electrodes follows a simple master curve governed by the time constant of the rate limiting process. We demonstrate that the master curve concept can be used to determine optimum design criteria meeting specific requirements in terms of maximum gravimetric capacity for a desired rate capability. The model further reveals practical limits of the electrode design, attesting the empirically well-known and inevitable tradeoff between energy and power density.

Corona magnetic field over sunspots estimated by m-wave observation

International Nuclear Information System (INIS)

Kurihara, Masahiro

1974-01-01

The shape of the magnetic field in corona was estimated from the observation of the type I storm occurred in the last decade of August, 1971. It was found from the observation with a 160 MHz interferometer at Mt. Nobeyama that at most three storm sources, which are called radio wave source, were produced. The radio wave sources were fixed above sunspots. The height of the radio wave sources was estimated to be 0.45 R from the photosphere. The sunspots under the radio wave sources can be classified to four sub-groups. Weakening of the magnetic field on the photosphere was found from the reduction of the area of some sub-group. The relation between the activity of type I storm and the intensity of the magnetic field of sunspots is qualitatively suggested. It is considered that the radio wave sources and the sunspots were connected by common magnetic force lines. The probable magnetic field in corona was presumed and is shown in a figure. An interesting point is that the direction of magnetic force lines inclined by about 30 0 outward to the vertical line to the photosphere surface. (Kato, T.)

On optimal (non-Trojan) semi-Latin squares with side n and block size n: Construction procedure and admissible permutations

International Nuclear Information System (INIS)

Chigbu, P.E.; Ukekwe, E.C.; Ikekeonwu, G.A.M.

2006-12-01

There is a special family of the (n x n)/k semi-Latin squares called the Trojan squares which are optimal among semi-Latin squares of equivalent sizes. Unfortunately, Trojan squares do not exist for all k; for instance, there is no Trojan square for k ≥ n. However, the need usually arises for constructing optimal semi-Latin squares where no Trojan squares exist. Bailey made a conjecture on optimal semi-Latin squares for k ≥ n and based on this conjecture, optimal non-Trojan semi-Latin squares are here constructed for k = n, considering the inherent Trojan squares for k < n. A lemma substantiating this conjecture for k = n is given and proved. In addition, the properties for the admissible permutation sets used in constructing these optimal squares are made evident based on the systematic-group-theoretic algorithm of Bailey and Chigbu. Algorithms for identifying the admissible permutations as well as constructing the optimal non-Trojan (n x n)/k = n semi-Latin squares for odd n and n = 4 are given. (author)

Semi-automatic construction of reference standards for evaluation of image registration

NARCIS (Netherlands)

Murphy, K.; Ginneken, van B.; Klein, S.; Staring, M.; Hoop, de B.J.; Viergever, M.A.; Pluim, J.P.W.

2011-01-01

Quantitative evaluation of image registration algorithms is a difficult and under-addressed issue due to the lack of a reference standard in most registration problems. In this work a method is presented whereby detailed reference standard data may be constructed in an efficient semi-automatic

The use of solar faculae in studies of the sunspot cycle

International Nuclear Information System (INIS)

Brown, G.M.; Evans, R.

1980-01-01

Comparison of the long-term variation of photospheric faculae areas with that of sunspots shows that studies of faculae provide both complementary and supplementary information on the behaviour of the solar cycle. Detailed studies of the development of sunspots with respect to faculae show that there is a high degree of order over much of a given cycle, but marked differences from cycle to cycle. Within a cycle the relationship between spot and faculae areas appears to be similar for the N and S solar hemispheres, and over the early stages of a cycle it is directly related to the magnitude of the maximum sunspot number subsequently attained in that cycle. This result may well have predictive applications, and formulae are given relating the peak sunspot number to simple parameters derived from this early developmental stage. Full application to the current cycle 21 is denied due to the cessation of the Greenwich daily photoheliographic measurements, but use of the cruder weekly data suggests a maximum smoothed sunspot number of 150 +- 22. The effects of the incompatibility of the spot and faculae data, in that faculae are unobservable over a large fraction of the solar disc and also do not always develop associated spots, have been examined in a detailed study of two cycles and shown not to vitiate the results. (orig.)

SUNSPOT CYCLES IMPACTS ON TOURISM AND QUALITY OF LIFE

Directory of Open Access Journals (Sweden)

Tadeja Jere Jakulin

2017-09-01

Full Text Available We live under the influence of natural cycles caused by the rotation of our planet and its revolution around the sun. The nature of our nearest star is also subject to cyclical change. This article presents a study of a correlation between sunspot cycles and foreign tourists arrivals in Slovenia, based on historical data between sunspot cycles and sea salt production in Slovenia's Municipality of Piran during the Maunder Minimum period (1645-1715. The production of salt by the solar evaporation of brine in salt pans and tourist industry are seasonal economic activities that are affected by changes to the weather. The paper looks at sea salt production in Piran during a particular period in the past. The repetition of the sea salt production in the past is not possible. For this reason, the study uses mathematical tools and an additional case study, which analyses arrivals of foreign tourists to Slovenia over the past 65 years (1948-2012. The study has two purposes: to identify a linear correlation coefficient, which provides evidence of a correlation between arrivals of foreign tourists to Slovenia and sunspot cycles and to develop a causal loop diagram (CLD or so called qualitative model of a complex tourism system, which shows the interdependency of sunspot cycles, tourism system, and quality of life.

Semi-Empirical Calibration of the Integral Equation Model for Co-Polarized L-Band Backscattering

Directory of Open Access Journals (Sweden)

Nicolas Baghdadi

2015-10-01

Full Text Available The objective of this paper is to extend the semi-empirical calibration of the backscattering Integral Equation Model (IEM initially proposed for Synthetic Aperture Radar (SAR data at C- and X-bands to SAR data at L-band. A large dataset of radar signal and in situ measurements (soil moisture and surface roughness over bare soil surfaces were used. This dataset was collected over numerous agricultural study sites in France, Luxembourg, Belgium, Germany and Italy using various SAR sensors (AIRSAR, SIR-C, JERS-1, PALSAR-1, ESAR. Results showed slightly better simulations with exponential autocorrelation function than with Gaussian function and with HH than with VV. Using the exponential autocorrelation function, the mean difference between experimental data and Integral Equation Model (IEM simulations is +0.4 dB in HH and −1.2 dB in VV with a Root Mean Square Error (RMSE about 3.5 dB. In order to improve the modeling results of the IEM for a better use in the inversion of SAR data, a semi-empirical calibration of the IEM was performed at L-band in replacing the correlation length derived from field experiments by a fitting parameter. Better agreement was observed between the backscattering coefficient provided by the SAR and that simulated by the calibrated version of the IEM (RMSE about 2.2 dB.

Semi-empirical proton binding constants for natural organic matter

Science.gov (United States)

Matynia, Anthony; Lenoir, Thomas; Causse, Benjamin; Spadini, Lorenzo; Jacquet, Thierry; Manceau, Alain

2010-03-01

Average proton binding constants ( KH,i) for structure models of humic (HA) and fulvic (FA) acids were estimated semi-empirically by breaking down the macromolecules into reactive structural units (RSUs), and calculating KH,i values of the RSUs using linear free energy relationships (LFER) of Hammett. Predicted log KH,COOH and log KH,Ph-OH are 3.73 ± 0.13 and 9.83 ± 0.23 for HA, and 3.80 ± 0.20 and 9.87 ± 0.31 for FA. The predicted constants for phenolic-type sites (Ph-OH) are generally higher than those derived from potentiometric titrations, but the difference may not be significant in view of the considerable uncertainty of the acidity constants determined from acid-base measurements at high pH. The predicted constants for carboxylic-type sites agree well with titration data analyzed with Model VI (4.10 ± 0.16 for HA, 3.20 ± 0.13 for FA; Tipping, 1998), the Impermeable Sphere model (3.50-4.50 for HA; Avena et al., 1999), and the Stockholm Humic Model (4.10 ± 0.20 for HA, 3.50 ± 0.40 for FA; Gustafsson, 2001), but differ by about one log unit from those obtained by Milne et al. (2001) with the NICA-Donnan model (3.09 ± 0.51 for HA, 2.65 ± 0.43 for FA), and used to derive recommended generic values. To clarify this ambiguity, 10 high-quality titration data from Milne et al. (2001) were re-analyzed with the new predicted equilibrium constants. The data are described equally well with the previous and new sets of values ( R2 ⩾ 0.98), not necessarily because the NICA-Donnan model is overparametrized, but because titration lacks the sensitivity needed to quantify the full binding properties of humic substances. Correlations between NICA-Donnan parameters are discussed, but general progress is impeded by the unknown number of independent parameters that can be varied during regression of a model fit to titration data. The high consistency between predicted and experimental KH,COOH values, excluding those of Milne et al. (2001), gives faith in the proposed

Physical Properties of Umbral Dots Observed in Sunspots: A Hinode Observation

Science.gov (United States)

Yadav, Rahul; Mathew, Shibu K.

2018-04-01

Umbral dots (UDs) are small-scale bright features observed in the umbral part of sunspots and pores. It is well established that they are manifestations of magnetoconvection phenomena inside umbrae. We study the physical properties of UDs in different sunspots and their dependence on decay rate and filling factor. We have selected high-resolution, G-band continuum filtergrams of seven sunspots from Hinode to study their physical properties. We have also used Michelson Doppler Imager (MDI) continuum images to estimate the decay rate of selected sunspots. An identification and tracking algorithm was developed to identify the UDs in time sequences. The statistical analysis of UDs exhibits an averaged maximum intensity and effective diameter of 0.26 I_{QS} and 270 km. Furthermore, the lifetime, horizontal speed, trajectory length, and displacement length (birth-death distance) of UDs are 8.19 minutes, 0.5 km s-1, 284 km, and 155 km, respectively. We also find a positive correlation between intensity-diameter, intensity-lifetime, and diameter-lifetime of UDs. However, UD properties do not show any significant relation with the decay rate or filling factor.

On the structure of small sunspots

International Nuclear Information System (INIS)

Ringnes, T.S.

1984-01-01

The smallest and most short-lived sunspots are decribed differently at the observatories in Zuerich and Greenwich. These differences which seem to originate both from the observing procedure and from the definitions of penumbra and umbra adopted, are further discussed

Sunspot number recalibration: The ~1840–1920 anomaly in the observer normalization factors of the group sunspot number

Directory of Open Access Journals (Sweden)

Cliver Edward W.

2017-01-01

Full Text Available We analyze the normalization factors (k′-factors used to scale secondary observers to the Royal Greenwich Observatory (RGO reference series of the Hoyt & Schatten (1998a, 1998b group sunspot number (GSN. A time series of these k′-factors exhibits an anomaly from 1841 to 1920, viz., the average k′-factor for all observers who began reporting groups from 1841 to 1883 is 1.075 vs. 1.431 for those who began from 1884 to 1920, with a progressive rise, on average, during the latter period. The 1883–1884 break between the two subintervals occurs precisely at the point where Hoyt and Schatten began to use a complex daisy-chaining method to scale observers to RGO. The 1841–1920 anomaly implies, implausibly, that the average sunspot observer who began from 1841 to 1883 was nearly as proficient at counting groups as mid-20th century RGO (for which k′ = 1.0 by definition while observers beginning during the 1884–1920 period regressed in group counting capability relative to those from the earlier interval. Instead, as shown elsewhere and substantiated here, RGO group counts increased relative to those of other long-term observers from 1874 to ~1915. This apparent inhomogeneity in the RGO group count series is primarily responsible for the increase in k′-factors from 1884 to 1920 and the suppression, by 44% on average, of the Hoyt and Schatten GSN relative to the original Wolf sunspot number (WSN before ~1885. Correcting for the early “learning curve” in the RGO reference series and minimizing the use of daisy-chaining rectifies the anomalous behavior of the k′-factor series. The resultant GSN time series (designated GSN* is in reasonable agreement with the revised WSN (SN*; Clette & Lefèvre 2016 and the backbone-based group sunspot number (RGS; Svalgaard & Schatten 2016 but significantly higher than other recent reconstructions (Friedli, personal communication, 2016; Lockwood et al. 2014a, 2014b; Usoskin et al. 2016a. This result

Calculation of bulk etch rate’s semi-empirical equation for polymer track membranes in stationary and dynamic modes

Directory of Open Access Journals (Sweden)

A. Mashentseva

2013-05-01

Full Text Available One of the most urgent and extremely social problems in environmental safeties area in Kazakhstan is providing the population of all regions of the country with quality drinking water. Development of filter elements based on nuclear track-etch membranes may be considered as one of best solutions this problem. The values of bulk etch rate and activation energy were calculated in view the effect of temperature, alkaline solution concentration as well as stirring effect. The semi-empirical equation of the bulk etch rate for PET track membranes was calculated. As a result of theoretical and experimental studies a semi-empirical equation of the bulk etch rate VB=3.4∙1012∙C2.07∙exp(-0.825/kT for 12 microns PET film, irradiated by ions 84Kr15+ (energy of 1.75 MeV/nucleon at the heavy ion accelerator DC-60 in Astana branch of the INP NNC RK, was obtained. 

SUNSPOT ROTATION AS A DRIVER OF MAJOR SOLAR ERUPTIONS IN THE NOAA ACTIVE REGION 12158

Energy Technology Data Exchange (ETDEWEB)

Vemareddy, P.; Ravindra, B. [Indian Institute of Astrophysics, Koramangala, Bangalore-560034 (India); Cheng, X., E-mail: vemareddy@iiap.res.in [School of Astronomy and Space Science, Nanjing University, Nanjing-210023 (China)

2016-09-20

We studied the development conditions of sigmoid structure under the influence of the magnetic non-potential characteristics of a rotating sunspot in the active region (AR) 12158. Vector magnetic field measurements from the Helioseismic Magnetic Imager and coronal EUV observations from the Atmospheric Imaging Assembly reveal that the erupting inverse-S sigmoid had roots at the location of the rotating sunspot. The sunspot rotates at a rate of 0°–5° h{sup −1} with increasing trend in the first half followed by a decrease. The time evolution of many non-potential parameters had a good correspondence with the sunspot rotation. The evolution of the AR magnetic structure is approximated by a time series of force-free equilibria. The non-linear force-free field magnetic structure around the sunspot manifests the observed sigmoid structure. Field lines from the sunspot periphery constitute the body of the sigmoid and those from the interior overlie the sigmoid, similar to a flux rope structure. While the sunspot was rotating, two major coronal mass ejection eruptions occurred in the AR. During the first (second) event, the coronal current concentrations were enhanced (degraded), consistent with the photospheric net vertical current; however, magnetic energy was released during both cases. The analysis results suggest that the magnetic connections of the sigmoid are driven by the slow motion of sunspot rotation, which transforms to a highly twisted flux rope structure in a dynamical scenario. Exceeding the critical twist in the flux rope probably leads to the loss of equilibrium, thus triggering the onset of the two eruptions.

Comparison of physical and semi-empirical hydraulic models for flood inundation mapping

Science.gov (United States)

Tavakoly, A. A.; Afshari, S.; Omranian, E.; Feng, D.; Rajib, A.; Snow, A.; Cohen, S.; Merwade, V.; Fekete, B. M.; Sharif, H. O.; Beighley, E.

2016-12-01

Various hydraulic/GIS-based tools can be used for illustrating spatial extent of flooding for first-responders, policy makers and the general public. The objective of this study is to compare four flood inundation modeling tools: HEC-RAS-2D, Gridded Surface Subsurface Hydrologic Analysis (GSSHA), AutoRoute and Height Above the Nearest Drainage (HAND). There is a trade-off among accuracy, workability and computational demand in detailed, physics-based flood inundation models (e.g. HEC-RAS-2D and GSSHA) in contrast with semi-empirical, topography-based, computationally less expensive approaches (e.g. AutoRoute and HAND). The motivation for this study is to evaluate this trade-off and offer guidance to potential large-scale application in an operational prediction system. The models were assessed and contrasted via comparability analysis (e.g. overlapping statistics) by using three case studies in the states of Alabama, Texas, and West Virginia. The sensitivity and accuracy of physical and semi-eimpirical models in producing inundation extent were evaluated for the following attributes: geophysical characteristics (e.g. high topographic variability vs. flat natural terrain, urbanized vs. rural zones, effect of surface roughness paratermer value), influence of hydraulic structures such as dams and levees compared to unobstructed flow condition, accuracy in large vs. small study domain, effect of spatial resolution in topographic data (e.g. 10m National Elevation Dataset vs. 0.3m LiDAR). Preliminary results suggest that semi-empericial models tend to underestimate in a flat, urbanized area with controlled/managed river channel around 40% of the inundation extent compared to the physical models, regardless of topographic resolution. However, in places where there are topographic undulations, semi-empericial models attain relatively higher level of accuracy than they do in flat non-urbanized terrain.

A semi-empirical method for measuring thickness of pipe-wall using gamma scattering technique

International Nuclear Information System (INIS)

Vo Hoang Nguyen; Hua Tuyet Le; Le Dinh Minh Quan; Hoang Duc Tam; Le Bao Tran; Tran Thien Thanh; Tran Nguyen Thuy Ngan; Chau Van Tao; VNUHCM-University of Science, Ho Chi Minh City; Huynh Dinh Chuong

2016-01-01

In this work, we propose a semi-empirical method for determining the thickness of pipe-wall, of which the determination is performed by combining the experimental and Monte Carlo simulation data. The testing measurements show that this is an efficient method to measure the thickness of pipe-wall. In addition, this work also shows that it could use a NaI(Tl) scintillation detector and a low activity source to measure the thickness of pipe-wall, which is simple, quick and high accuracy method. (author)

Wings of the butterfly: Sunspot groups for 1826-2015

Science.gov (United States)

Leussu, R.; Usoskin, I. G.; Senthamizh Pavai, V.; Diercke, A.; Arlt, R.; Denker, C.; Mursula, K.

2017-03-01

The spatio-temporal evolution of sunspot activity, the so-called Maunder butterfly diagram, has been continously available since 1874 using data from the Royal Greenwich Observatory, extended by SOON network data after 1976. Here we present a new extended butterfly diagram of sunspot group occurrence since 1826, using the recently digitized data from Schwabe (1826-1867) and Spörer (1866-1880). The wings of the diagram are separated using a recently developed method based on an analysis of long gaps in sunspot group occurrence in different latitude bands. We define characteristic latitudes, corresponding to the start, end, and the largest extent of the wings (the F, L, and H latitudes). The H latitudes (30°-45°) are highly significantly correlated with the strength of the wings (quantified by the total sum of the monthly numbers of sunspot groups). The F latitudes (20°-30°) depict a weak tendency, especially in the southern hemisphere, to follow the wing strength. The L latitudes (2°-10°) show no clear relation to the wing strength. Overall, stronger cycle wings tend to start at higher latitudes and have a greater wing extent. A strong (5-6)-cycle periodic oscillation is found in the start and end times of the wings and in the overlap and gaps between successive wings of one hemisphere. While the average wing overlap is zero in the southern hemisphere, it is two to three months in the north. A marginally significant oscillation of about ten solar cycles is found in the asymmetry of the L latitudes. The new long database of butterfly wings provides new observational constraints to solar dynamo models that discuss the spatio-temporal distribution of sunspot occurrence over the solar cycle and longer. Digital data for Fig. 1 are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A131

Sunspots sketches during the solar eclipses of 9th January and 29th December of 1777 in Mexico

Science.gov (United States)

Domínguez-Castro, Fernando; Gallego, María Cruz; Vaquero, José Manuel

2017-06-01

Two sunspot observations recorded by the Mexican Felipe de Zúñiga y Ontiveros have been revealed from a manuscript. One sunspot group was recorded on 9th January 1777 and four sunspot groups on 29th December 1777. Both records were taken during the observation of solar eclipses from Mexico City and their description also included sketches of the solar disk with sunspots. The sunspot group corresponding to 9th January was also observed by Erasmus Lievog. The observation on 29th December 1777 is the only record corresponding to this date.

On two populations of sunspot groups

International Nuclear Information System (INIS)

Kuklin, G.V.

1980-01-01

The principal component method was applied studying the sunspot groups distribution in respect to the maximum area for the individual 11-year cycles 12 to 19 (Lopez Arroyo and Lahulla, 1974) and for the years 1900 to 1964 (Mandrykina, 1974). The existence of two populations of sunspot groups is confirmed. The variations of the importance parameter q, which determines the population shares, in the 80-, 22- and 11-year cycles are considered. The obtained maximal area distributions for populations I and II are approximated by linear combination of logarithmic-normal distributions, the subpopulations Ia, Ib, Ic by the most probable maximum areas of 22, 298 and 90 mvh, respectively, and the subpopulations IIa, IIb, IIc by the most probable maximal areas of 6, 142 and 754 mvh, respectively. The characteristic distinction between populations I and II is apparently the magnetic structure of the groups belonging to them (bipolar and unipolar ones). (author)

The performance of selected semi-empirical and DFT methods in studying C60 fullerene derivatives

Science.gov (United States)

Sikorska, Celina; Puzyn, Tomasz

2015-11-01

The capability of reproducing the open circuit voltages (V oc) of 15 representative C60 fullerene derivatives was tested using the selected quantum mechanical methods (B3LYP, PM6, and PM7) together with the two one-electron basis sets. Certain theoretical treatments (e.g. PM6) were found to be satisfactory for preliminary estimates of the open circuit voltages (V oc), whereas the use of the B3LYP/6-31G(d) approach has been proven to assure highly accurate results. We also examined the structural similarity of 19 fullerene derivatives by employing principle component analysis (PCA). In order to express the structural features of the studied compounds we used molecular descriptors calculated with semi-empirical (PM6 and PM7) and density functional (B3LYP/6-31G(d)) methods separately. In performing PCA, we noticed that semi-empirical methods (i.e. PM6 and PM7) seem satisfactory for molecules, in which one can distinguish the aromatic and the aliphatic parts in the cyclopropane ring of PCBM (phenyl-C61-buteric acid methyl ester) and they significantly overestimate the energy of the highest occupied molecular orbital (E HOMO). The use of the B3LYP functional, however, is recommended for studying methanofullerenes, which closely resemble the structure of PCBM, and for their modifications.

The performance of selected semi-empirical and DFT methods in studying C60 fullerene derivatives

International Nuclear Information System (INIS)

Sikorska, Celina; Puzyn, Tomasz

2015-01-01

The capability of reproducing the open circuit voltages (V oc ) of 15 representative C 60 fullerene derivatives was tested using the selected quantum mechanical methods (B3LYP, PM6, and PM7) together with the two one-electron basis sets. Certain theoretical treatments (e.g. PM6) were found to be satisfactory for preliminary estimates of the open circuit voltages (V oc ), whereas the use of the B3LYP/6-31G(d) approach has been proven to assure highly accurate results. We also examined the structural similarity of 19 fullerene derivatives by employing principle component analysis (PCA). In order to express the structural features of the studied compounds we used molecular descriptors calculated with semi-empirical (PM6 and PM7) and density functional (B3LYP/6-31G(d)) methods separately. In performing PCA, we noticed that semi-empirical methods (i.e. PM6 and PM7) seem satisfactory for molecules, in which one can distinguish the aromatic and the aliphatic parts in the cyclopropane ring of PCBM (phenyl-C 61 -buteric acid methyl ester) and they significantly overestimate the energy of the highest occupied molecular orbital (E HOMO ). The use of the B3LYP functional, however, is recommended for studying methanofullerenes, which closely resemble the structure of PCBM, and for their modifications. (paper)

The performance of selected semi-empirical and DFT methods in studying C₆₀ fullerene derivatives.

Science.gov (United States)

Sikorska, Celina; Puzyn, Tomasz

2015-11-13

The capability of reproducing the open circuit voltages (V(oc)) of 15 representative C60 fullerene derivatives was tested using the selected quantum mechanical methods (B3LYP, PM6, and PM7) together with the two one-electron basis sets. Certain theoretical treatments (e.g. PM6) were found to be satisfactory for preliminary estimates of the open circuit voltages (V(oc)), whereas the use of the B3LYP/6-31G(d) approach has been proven to assure highly accurate results. We also examined the structural similarity of 19 fullerene derivatives by employing principle component analysis (PCA). In order to express the structural features of the studied compounds we used molecular descriptors calculated with semi-empirical (PM6 and PM7) and density functional (B3LYP/6-31G(d)) methods separately. In performing PCA, we noticed that semi-empirical methods (i.e. PM6 and PM7) seem satisfactory for molecules, in which one can distinguish the aromatic and the aliphatic parts in the cyclopropane ring of PCBM (phenyl-C61-buteric acid methyl ester) and they significantly overestimate the energy of the highest occupied molecular orbital (E(HOMO)). The use of the B3LYP functional, however, is recommended for studying methanofullerenes, which closely resemble the structure of PCBM, and for their modifications.

MEASUREMENTS OF THE ABSORPTION AND SCATTERING CROSS SECTIONS FOR THE INTERACTION OF SOLAR ACOUSTIC WAVES WITH SUNSPOTS

International Nuclear Information System (INIS)

Zhao, Hui; Chou, Dean-Yi

2016-01-01

The solar acoustic waves are modified by the interaction with sunspots. The interaction can be treated as a scattering problem: an incident wave propagating toward a sunspot is scattered by the sunspot into different modes. The absorption cross section and scattering cross section are two important parameters in the scattering problem. In this study, we use the wavefunction of the scattered wave, measured with a deconvolution method, to compute the absorption cross section σ ab and the scattering cross section σ sc for the radial order n = 0–5 for two sunspots, NOAA 11084 and NOAA 11092. In the computation of the cross sections, the random noise and dissipation in the measured acoustic power are corrected. For both σ ab and σ sc , the value of NOAA 11092 is greater than that of NOAA 11084, but their overall n dependence is similar: decreasing with n . The ratio of σ ab of NOAA 11092 to that of NOAA 11084 approximately equals the ratio of sunspot radii for all n , while the ratio of σ sc of the two sunspots is greater than the ratio of sunspot radii and increases with n . This suggests that σ ab is approximately proportional to the sunspot radius, while the dependence of σ sc on radius is faster than the linear increase.

MEASUREMENTS OF THE ABSORPTION AND SCATTERING CROSS SECTIONS FOR THE INTERACTION OF SOLAR ACOUSTIC WAVES WITH SUNSPOTS

Energy Technology Data Exchange (ETDEWEB)

Zhao, Hui [National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 200012 (China); Chou, Dean-Yi, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)

2016-05-01

The solar acoustic waves are modified by the interaction with sunspots. The interaction can be treated as a scattering problem: an incident wave propagating toward a sunspot is scattered by the sunspot into different modes. The absorption cross section and scattering cross section are two important parameters in the scattering problem. In this study, we use the wavefunction of the scattered wave, measured with a deconvolution method, to compute the absorption cross section σ {sub ab} and the scattering cross section σ {sub sc} for the radial order n = 0–5 for two sunspots, NOAA 11084 and NOAA 11092. In the computation of the cross sections, the random noise and dissipation in the measured acoustic power are corrected. For both σ {sub ab} and σ {sub sc}, the value of NOAA 11092 is greater than that of NOAA 11084, but their overall n dependence is similar: decreasing with n . The ratio of σ {sub ab} of NOAA 11092 to that of NOAA 11084 approximately equals the ratio of sunspot radii for all n , while the ratio of σ {sub sc} of the two sunspots is greater than the ratio of sunspot radii and increases with n . This suggests that σ {sub ab} is approximately proportional to the sunspot radius, while the dependence of σ {sub sc} on radius is faster than the linear increase.

Frequently Occurring Reconnection Jets from Sunspot Light Bridges

Science.gov (United States)

Tian, Hui; Yurchyshyn, Vasyl; Peter, Hardi; Solanki, Sami K.; Young, Peter R.; Ni, Lei; Cao, Wenda; Ji, Kaifan; Zhu, Yingjie; Zhang, Jingwen; Samanta, Tanmoy; Song, Yongliang; He, Jiansen; Wang, Linghua; Chen, Yajie

2018-02-01

Solid evidence of magnetic reconnection is rarely reported within sunspots, the darkest regions with the strongest magnetic fields and lowest temperatures in the solar atmosphere. Using the world’s largest solar telescope, the 1.6 m Goode Solar Telescope, we detect prevalent reconnection through frequently occurring fine-scale jets in the Hα line wings at light bridges, the bright lanes that may divide the dark sunspot core into multiple parts. Many jets have an inverted Y-shape, shown by models to be typical of reconnection in a unipolar field environment. Simultaneous spectral imaging data from the Interface Region Imaging Spectrograph show that the reconnection drives bidirectional flows up to 200 km s‑1, and that the weakly ionized plasma is heated by at least an order of magnitude up to ∼80,000 K. Such highly dynamic reconnection jets and efficient heating should be properly accounted for in future modeling efforts of sunspots. Our observations also reveal that the surge-like activity previously reported above light bridges in some chromospheric passbands such as the Hα core has two components: the ever-present short surges likely to be related to the upward leakage of magnetoacoustic waves from the photosphere, and the occasionally occurring long and fast surges that are obviously caused by the intermittent reconnection jets.

Semi-empirical long-term cycle life model coupled with an electrolyte depletion function for large-format graphite/LiFePO4 lithium-ion batteries

Science.gov (United States)

Park, Joonam; Appiah, Williams Agyei; Byun, Seoungwoo; Jin, Dahee; Ryou, Myung-Hyun; Lee, Yong Min

2017-10-01

To overcome the limitation of simple empirical cycle life models based on only equivalent circuits, we attempt to couple a conventional empirical capacity loss model with Newman's porous composite electrode model, which contains both electrochemical reaction kinetics and material/charge balances. In addition, an electrolyte depletion function is newly introduced to simulate a sudden capacity drop at the end of cycling, which is frequently observed in real lithium-ion batteries (LIBs). When simulated electrochemical properties are compared with experimental data obtained with 20 Ah-level graphite/LiFePO4 LIB cells, our semi-empirical model is sufficiently accurate to predict a voltage profile having a low standard deviation of 0.0035 V, even at 5C. Additionally, our model can provide broad cycle life color maps under different c-rate and depth-of-discharge operating conditions. Thus, this semi-empirical model with an electrolyte depletion function will be a promising platform to predict long-term cycle lives of large-format LIB cells under various operating conditions.

Semi-empirical model for the calculation of flow friction factors in wire-wrapped rod bundles

International Nuclear Information System (INIS)

Carajilescov, P.; Fernandez y Fernandez, E.

1981-08-01

LMFBR fuel elements consist of wire-wrapped rod bundles, with triangular array, with the fluid flowing parallel to the rods. A semi-empirical model is developed in order to obtain the average bundle friction factor, as well as the friction factor for each subchannel. The model also calculates the flow distribution factors. The results are compared to experimental data for geometrical parameters in the range: P(div)D = 1.063 - 1.417, H(div)D = 4 - 50, and are considered satisfactory. (Author) [pt

A semi-empirical approach to calculate gamma activities in environmental samples

International Nuclear Information System (INIS)

Palacios, D.; Barros, H.; Alfonso, J.; Perez, K.; Trujillo, M.; Losada, M.

2006-01-01

We propose a semi-empirical method to calculate radionuclide concentrations in environmental samples without the use of reference material and avoiding the typical complexity of Monte-Carlo codes. The calculation of total efficiencies was carried out from a relative efficiency curve (obtained from the gamma spectra data), and the geometric (simulated by Monte-Carlo), absorption, sample and intrinsic efficiencies at energies between 130 and 3000 keV. The absorption and sample efficiencies were determined from the mass absorption coefficients, obtained by the web program XCOM. Deviations between computed results and measured efficiencies for the RGTh-1 reference material are mostly within 10%. Radionuclide activities in marine sediment samples calculated by the proposed method and by the experimental relative method were in satisfactory agreement. The developed method can be used for routine environmental monitoring when efficiency uncertainties of 10% can be sufficient.(Author)

Electron momentum density and Compton profile by a semi-empirical approach

Science.gov (United States)

Aguiar, Julio C.; Mitnik, Darío; Di Rocco, Héctor O.

2015-08-01

Here we propose a semi-empirical approach to describe with good accuracy the electron momentum densities and Compton profiles for a wide range of pure crystalline metals. In the present approach, we use an experimental Compton profile to fit an analytical expression for the momentum densities of the valence electrons. This expression is similar to a Fermi-Dirac distribution function with two parameters, one of which coincides with the ground state kinetic energy of the free-electron gas and the other resembles the electron-electron interaction energy. In the proposed scheme conduction electrons are neither completely free nor completely bound to the atomic nucleus. This procedure allows us to include correlation effects. We tested the approach for all metals with Z=3-50 and showed the results for three representative elements: Li, Be and Al from high-resolution experiments.

A semi-empirical molecular orbital model of silica, application to radiation compaction

International Nuclear Information System (INIS)

Tasker, P.W.

1978-11-01

Semi-empirical molecular-orbital theory is used to calculate the bonding in a cluster of two SiO 4 tetrahedra, with the outer bonds saturated with pseudo-hydrogen atoms. The basic properties of the cluster, bond energies and band gap are calculated using a very simple parameterisation scheme. The resulting cluster is used to study the rebonding that occurs when an oxygen vacancy is created. It is suggested that a vacancy model is capable of producing the observed differences between quartz and vitreous silica, and the calculations show that the compaction effect observed in the glass is of a magnitude compatible with the relaxations around the vacancy. More detailed lattice models will be needed to examine this mechanism further. (author)

On Solar Granulations, Limb Darkening, and Sunspots: Brief Insights in Remembrance of Father Angelo Secchi

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2011-07-01

Full Text Available Father Angelo Secchi used the existence of solar granulation as a central line of rea- soning when he advanced that the Sun was a gaseous body with a photosphere contain- ing incandescent particulate matter (Secchi A. Sulla Struttura della Fotosfera Solare. Bullettino Meteorologico dell’Osservatorio del Collegio Romano , 30 November 1864, v.3(11, 1–3. Secchi saw the granules as condensed matter emitting the photospheric spectrum, while the darkened intergranular lanes conveyed the presence of a gaseous solar interior. Secchi also considered the nature of sunspots and limb darkening. In the context of modern solar models, opacity arguments currently account for the emis- sive properties of the photosphere. Optical depth is thought to explain limb darkening. Both temperature variations and magnetic fields are invoked to justify the weakened emissivities of sunspots, even though the presence of static magnetic fields in materi- als is not usually associated with modified emissivity. Conversely, within the context of a liquid metallic hydrogen solar model, the appearance of granules, limb darkening, and sunspots can be elegantly understood through the varying directional emissivity of condensed matter. A single explanation is applicable to all three phenomena. Granular contrast can be directly associated with the generation of limb darkening. Depending on size, granules can be analyzed by considering Kolmogoroff’s formulations and B ́ enard convection, respectively, both of which were observed using incompressible liquids, not gases. Granules follow the 2-dimensional space filling laws of Aboav-Weiner and Lewis. Their adherence to these structural laws provides supportive evidence that the granular surface of the Sun represents elements which can only be constructed from condensed matter. A gaseous Sun cannot be confined to a 2-dimensional framework. Mesogranules, supergranules, and giant cells constitute additional entities which further

Estimation of Aboveground Biomass in Alpine Forests: A Semi-Empirical Approach Considering Canopy Transparency Derived from Airborne LiDAR Data

Directory of Open Access Journals (Sweden)

Martin Rutzinger

2010-12-01

Full Text Available In this study, a semi-empirical model that was originally developed for stem volume estimation is used for aboveground biomass (AGB estimation of a spruce dominated alpine forest. The reference AGB of the available sample plots is calculated from forest inventory data by means of biomass expansion factors. Furthermore, the semi-empirical model is extended by three different canopy transparency parameters derived from airborne LiDAR data. These parameters have not been considered for stem volume estimation until now and are introduced in order to investigate the behavior of the model concerning AGB estimation. The developed additional input parameters are based on the assumption that transparency of vegetation can be measured by determining the penetration of the laser beams through the canopy. These parameters are calculated for every single point within the 3D point cloud in order to consider the varying properties of the vegetation in an appropriate way. Exploratory Data Analysis (EDA is performed to evaluate the influence of the additional LiDAR derived canopy transparency parameters for AGB estimation. The study is carried out in a 560 km2 alpine area in Austria, where reference forest inventory data and LiDAR data are available. The investigations show that the introduction of the canopy transparency parameters does not change the results significantly according to R2 (R2 = 0.70 to R2 = 0.71 in comparison to the results derived from, the semi-empirical model, which was originally developed for stem volume estimation.

Interface of the polarizable continuum model of solvation with semi-empirical methods in the GAMESS program.

Directory of Open Access Journals (Sweden)

Casper Steinmann

Full Text Available An interface between semi-empirical methods and the polarized continuum model (PCM of solvation successfully implemented into GAMESS following the approach by Chudinov et al (Chem. Phys. 1992, 160, 41. The interface includes energy gradients and is parallelized. For large molecules such as ubiquitin a reasonable speedup (up to a factor of six is observed for up to 16 cores. The SCF convergence is greatly improved by PCM for proteins compared to the gas phase.

Prediction of Physicochemical Properties of Organic Molecules Using Semi-Empirical Methods

International Nuclear Information System (INIS)

Kim, Chan Kyung; Kim, Chang Kon; Kim, Miri; Lee, Hai Whang; Cho, Soo Gyeong

2013-01-01

Prediction of physicochemical properties of organic molecules is an important process in chemistry and chemical engineering. The MSEP approach developed in our lab calculates the molecular surface electrostatic potential (ESP) on van der Waals (vdW) surfaces of molecules. This approach includes geometry optimization and frequency calculation using hybrid density functional theory, B3LYP, at the 6-31G(d) basis set to find minima on the potential energy surface, and is known to give satisfactory QSPR results for various properties of organic molecules. However, this MSEP method is not applicable to screen large database because geometry optimization and frequency calculation require considerable computing time. To develop a fast but yet reliable approach, we have re-examined our previous work on organic molecules using two semi-empirical methods, AM1 and PM3. This new approach can be an efficient protocol in designing new molecules with improved properties

Sunspot activity and influenza pandemics: a statistical assessment of the purported association.

Science.gov (United States)

Towers, S

2017-10-01

Since 1978, a series of papers in the literature have claimed to find a significant association between sunspot activity and the timing of influenza pandemics. This paper examines these analyses, and attempts to recreate the three most recent statistical analyses by Ertel (1994), Tapping et al. (2001), and Yeung (2006), which all have purported to find a significant relationship between sunspot numbers and pandemic influenza. As will be discussed, each analysis had errors in the data. In addition, in each analysis arbitrary selections or assumptions were also made, and the authors did not assess the robustness of their analyses to changes in those arbitrary assumptions. Varying the arbitrary assumptions to other, equally valid, assumptions negates the claims of significance. Indeed, an arbitrary selection made in one of the analyses appears to have resulted in almost maximal apparent significance; changing it only slightly yields a null result. This analysis applies statistically rigorous methodology to examine the purported sunspot/pandemic link, using more statistically powerful un-binned analysis methods, rather than relying on arbitrarily binned data. The analyses are repeated using both the Wolf and Group sunspot numbers. In all cases, no statistically significant evidence of any association was found. However, while the focus in this particular analysis was on the purported relationship of influenza pandemics to sunspot activity, the faults found in the past analyses are common pitfalls; inattention to analysis reproducibility and robustness assessment are common problems in the sciences, that are unfortunately not noted often enough in review.

The construction of the ATLAS semi-conductor tracker

International Nuclear Information System (INIS)

Jones, Tim

2006-01-01

The ATLAS (A Toroidal LHC ApparatuS) experiment at the Large Hadron Collider (LHC) at CERN has been designed to explore physics at the TeV energy scale and will be commissioned in 2007. In the innermost region of the experiment is a charged particle tracker, the Inner Detector of which the Semiconductor Tracker (SCT) is a major component. The SCT comprises a central barrel section enclosed by two endcaps (A and C). The construction of the major components of the ATLAS Semi-conductor tracker (SCT) is now nearing completion. Following a brief description of the design of the SCT, the logistics and organisation of the construction phase of the project are discussed. Central to the delivery of a high quality detector is the testing of large numbers of modules both during assembly and after they are mounted on their final support structures. The results of these tests for endcap C are presented showing that the electrical performance of the 988 modules to be installed in ATLAS is compatible with the specifications required

DYNAMICS IN SUNSPOT UMBRA AS SEEN IN NEW SOLAR TELESCOPE AND INTERFACE REGION IMAGING SPECTROGRAPH DATA

Energy Technology Data Exchange (ETDEWEB)

Yurchyshyn, V.; Abramenko, V. [Big Bear Solar Observatory, New Jersey Institute of Technology, Big Bear City, CA 92314 (United States); Kilcik, A. [Department of Space Science and Technologies, Akdeniz University, 07058 Antalya (Turkey)

2015-01-10

We analyze sunspot oscillations using Interface Region Imaging Spectrograph (IRIS) slit-jaw and spectral data and narrow-band chromospheric images from the New Solar Telescope (NST) for the main sunspot in NOAA AR 11836. We report that the difference between the shock arrival times as measured by the Mg II k 2796.35 Å and Si IV 1393.76 Å line formation levels changes during the observed period, and peak-to-peak delays may range from 40 s to zero. The intensity of chromospheric shocks also displays long-term (about 20 min) variations. NST's high spatial resolution Hα data allowed us to conclude that, in this sunspot, umbral flashes (UFs) appeared in the form of narrow bright lanes stretched along the light bridges and around clusters of umbral bright points. The time series also suggested that UFs preferred to appear on the sunspot-center side of light bridges, which may indicate the existence of a compact sub-photospheric driver of sunspot oscillations. The sunspot's umbra as seen in the IRIS chromospheric and transition region data appears bright above the locations of light bridges and the areas where the dark umbra is dotted with clusters of umbral dots. Co-spatial and co-temporal data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory showed that the same locations were associated with bright footpoints of coronal loops suggesting that the light bridges may play an important role in heating the coronal sunspot loops. Finally, the power spectra analysis showed that the intensity of chromospheric and transition region oscillations significantly vary across the umbra and with height, suggesting that umbral non-uniformities and the structure of sunspot magnetic fields may play a role in wave propagation and heating of umbral loops.

Empirical Refinements of a Molecular Genetics Learning Progression: The Molecular Constructs

Science.gov (United States)

Todd, Amber; Kenyon, Lisa

2016-01-01

This article describes revisions to four of the eight constructs of the Duncan molecular genetics learning progression [Duncan, Rogat, & Yarden, (2009)]. As learning progressions remain hypothetical models until validated by multiple rounds of empirical studies, these revisions are an important step toward validating the progression. Our…

Determination of the Alfvén Speed and Plasma-beta Using the Seismology of Sunspot Umbra

Energy Technology Data Exchange (ETDEWEB)

Cho, I.-H.; Moon, Y.-J.; Nakariakov, V. M.; Park, J.; Choi, S. [Department of Astronomy and Space Science, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Cho, K.-S.; Bong, S.-C.; Baek, J.-H.; Kim, Y.-H.; Lee, J., E-mail: ihjo@khu.ac.kr [Space Science Division, Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

2017-03-01

For 478 centrally located sunspots observed in the optical continuum with Solar Dynamics Observatory /Helioseismic Magnetic Imager, we perform seismological diagnostics of the physical parameters of umbral photospheres. The new technique is based on the theory of slow magnetoacoustic waves in a non-isothermally stratified photosphere with a uniform vertical magnetic field. We construct a map of the weighted frequency of three-minute oscillations inside the umbra and use it for the estimation of the Alfvén speed, plasma-beta, and mass density within the umbra. We find the umbral mean Alfvén speed ranges between 10.5 and 7.5 km s{sup −1} and is negatively correlated with magnetic field strength. The umbral mean plasma-beta is found to range approximately between 0.65 and 1.15 and does not vary significantly from pores to mature sunspots. The mean density ranges between (1–6) × 10{sup −4} kg m{sup −3} and shows a strong positive correlation with magnetic field strength.

Rock models at Zielona Gora, Poland applied to the semi-empirical neutron tool calibration

International Nuclear Information System (INIS)

Czubek, J.A.; Ossowski, A.; Zorski, T.; Massalski, T.

1995-01-01

The semi-empirical calibration method applied to the neutron porosity tool is presented in this paper. It was used with the ODSN-102 tool of 70 mm diameter and equipped with an Am-Be neutron source at the calibration facility of Zielona Gora, Poland, inside natural and artificial rocks: four sandstone, four limestone and one dolomite block with borehole diameters of 143 and 216 mm, and three artificial ceramic blocks with borehole diameters of 90 and 180 mm. All blocks were saturated with fresh water, and fresh water was also inside all boreholes. In five blocks mineralized water (200,000 ppm NaCl) was introduced inside the boreholes. All neutron characteristics of the calibration blocks are given in this paper. The semi-empirical method of calibration correlates the tool readings observed experimentally with the general neutron parameter (GNP). This results in a general calibration curve, where the tool readings (TR) vs GNP are situated at one curve irrespective of their origin, i.e. of the formation lithology, borehole diameter, tool stand-off, brine salinity, etc. The n and m power coefficients are obtained experimentally during the calibration procedure. The apparent neutron parameters are defined as those sensed by a neutron tool situated inside the borehole and in real environmental conditions. When they are known, the GNP parameter can be computed analytically for the whole range of porosity at any kind of borehole diameter, formation lithology (including variable rock matrix absorption cross-section and density), borehole and formation salinity, tool stand-off and drilling fluid physical parameters. By this approach all porosity corrections with respect to the standard (e.g. limestone) calibration curve can be generated. (author)

Studies of kinematic elements in two multicenter sunspot groups

International Nuclear Information System (INIS)

Korobova, Z.B.

1983-01-01

Some features of kinematic elements (KE) in two multicenter sunspot groups were studied using Tashkent full-disc white light heliograms. KE and morphological elements do not reveal any relationship. A KE coincides with a unipolar or multipolar spot or with part of a spot. It may also contain an extended stream including several spots. Relation of KE to large-scale photospheric magnetic fields is less clear. The line of polarity reversal is, in most cases, the deviding line between two adjacent KE. At the same time, a KE can contain spots of both polarities. Sunspot trajectories in the leading polarity regions show the best similarity. Interactions of KE are greatly influenced by the meridional drift. (author)

An Empirical Investigation of Strategic Planning in QS Practices

OpenAIRE

Murphy, Roisin

2012-01-01

The benefit of engaging in strategic planning has been well documented over several decades of strategic management research. Despite the significant body of existing knowledge in the field, there remains a limited collection of empirically tested research pertaining to strategic planning within professional service firms (PSFs) in construction, particularly from an Irish context. The research is an exploratory study involving in-depth, semi-structured interviews and a widespread survey of...

SOLAR VARIABILITY FROM 240 TO 1750 nm IN TERMS OF FACULAE BRIGHTENING AND SUNSPOT DARKENING FROM SCIAMACHY

International Nuclear Information System (INIS)

Pagaran, J.; Weber, M.; Burrows, J.

2009-01-01

The change of spectral decomposition of the total radiative output on various timescales of solar magnetic activity is of large interest to terrestrial and solar-stellar atmosphere studies. Starting in 2002, SCIAMACHY was the first satellite instrument to observe daily solar spectral irradiance (SSI) continuously from 230 nm (UV) to 1750 nm (near-infrared; near-IR). In order to address the question of how much UV, visible (vis), and IR spectral regions change on 27 day and 11 year timescales, we parameterize short-term SSI variations in terms of faculae brightening (Mg II index) and sunspot darkening (photometric sunspot index) proxies. Although spectral variations above 300 nm are below 1% and, therefore, well below the accuracy of absolute radiometric calibration, relative accuracy for short-term changes is shown to be in the per mill range. This enables us to derive short-term spectral irradiance variations from the UV to the near-IR. During Halloween solar storm in 2003 with a record high sunspot area, we observe a reduction of 0.3% in the near-IR to 0.5% in the vis and near-UV. This is consistent with a 0.4% reduction in total solar irradiance (TSI). Over an entire 11 year solar cycle, SSI variability covering simultaneously the UV, vis, and IR spectral regions have not been directly observed so far. Using variations of solar proxies over solar cycle 23, solar cycle spectral variations have been estimated using scaling factors that best matched short-term variations of SCIAMACHY. In the 300-400 nm region, which strongly contributes to TSI solar cycle change, a contribution of 34% is derived from SCIAMACHY observations, which is lower than the reported values from SUSIM satellite data and the empirical SATIRE model. The total UV contribution (below 400 nm) to TSI solar cycle variations is estimated to be 55%.

Photospheric Origin of Three-minute Oscillations in a Sunspot

Energy Technology Data Exchange (ETDEWEB)

Chae, Jongchul; Lee, Jeongwoo; Cho, Kyuhyoun; Song, Donguk [Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Cho, Kyungsuk; Yurchyshyn, Vasyl [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of)

2017-02-10

The origin of the three-minute oscillations of intensity and velocity observed in the chromosphere of sunspot umbrae is still unclear. We investigated the spatio-spectral properties of the 3 minute oscillations of velocity in the photosphere of a sunspot umbra as well as those in the low chromosphere using the spectral data of the Ni i λ 5436, Fe i λ 5435, and Na i D{sub 2} λ 5890 lines taken by the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. As a result, we found a local enhancement of the 3 minute oscillation power in the vicinities of a light bridge (LB) and numerous umbral dots (UDs) in the photosphere. These 3 minute oscillations occurred independently of the 5 minute oscillations. Through wavelet analysis, we determined the amplitudes and phases of the 3 minute oscillations at the formation heights of the spectral lines, and they were found to be consistent with the upwardly propagating slow magnetoacoustic waves in the photosphere with energy flux large enough to explain the chromospheric oscillations. Our results suggest that the 3 minute chromospheric oscillations in this sunspot may have been generated by magnetoconvection occurring in the LB and UDs.

Outflow of chromospheric emission features from the rim of a sunspot

Science.gov (United States)

Liu, S.-Y.

1973-01-01

In viewing a 16 mm movie made from a time sequence of spectroheliograms, some of these emission features are found to move outward from the rim of the sunspot until they are eventually lost in the small plage. There are two interpretations for the streaming of the magnetic features. It is possible that kinks in the line of force propagate along a horizontal extension of the penumbral magnetic field. Alternatively, fragments of the sunspot magnetic field are carried away by the photospheric velocity field.

A one-dimensional semi-empirical model considering transition boiling effect for dispersed flow film boiling

Energy Technology Data Exchange (ETDEWEB)

Wang, Yu-Jou [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Pan, Chin, E-mail: cpan@ess.nthu.edu.tw [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Low Carbon Energy Research Center, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China)

2017-05-15

Highlights: • Seven heat transfer mechanisms are studied numerically by the model. • A semi-empirical method is proposed to account for the transition boiling effect. • The parametric effects on the heat transfer mechanisms are investigated. • The thermal non-equilibrium phenomenon between vapor and droplets is investigated. - Abstract: The objective of this paper is to develop a one-dimensional semi-empirical model for the dispersed flow film boiling considering transition boiling effects. The proposed model consists of conservation equations, i.e., vapor mass, vapor energy, droplet mass and droplet momentum conservation, and a set of closure relations to address the interactions among wall, vapor and droplets. The results show that the transition boiling effect is of vital importance in the dispersed flow film boiling regime, since the flowing situation in the downstream would be influenced by the conditions in the upstream. In addition, the present paper, through evaluating the vapor temperature and the amount of heat transferred to droplets, investigates the thermal non-equilibrium phenomenon under different flowing conditions. Comparison of the wall temperature predictions with the 1394 experimental data in the literature, the present model ranging from system pressure of 30–140 bar, heat flux of 204–1837 kW/m{sup 2} and mass flux of 380–5180 kg/m{sup 2} s, shows very good agreement with RMS of 8.80% and standard deviation of 8.81%. Moreover, the model well depicts the thermal non-equilibrium phenomenon for the dispersed flow film boiling.

New reconstruction of the sunspot group numbers since 1739 using direct calibration and "backbone" methods

Science.gov (United States)

Chatzistergos, Theodosios; Usoskin, Ilya G.; Kovaltsov, Gennady A.; Krivova, Natalie A.; Solanki, Sami K.

2017-06-01

Context. The group sunspot number (GSN) series constitute the longest instrumental astronomical database providing information on solar activity. This database is a compilation of observations by many individual observers, and their inter-calibration has usually been performed using linear rescaling. There are multiple published series that show different long-term trends for solar activity. Aims: We aim at producing a GSN series, with a non-linear non-parametric calibration. The only underlying assumptions are that the differences between the various series are due to different acuity thresholds of the observers, and that the threshold of each observer remains constant throughout the observing period. Methods: We used a daisy chain process with backbone (BB) observers and calibrated all overlapping observers to them. We performed the calibration of each individual observer with a probability distribution function (PDF) matrix constructed considering all daily values for the overlapping period with the BB. The calibration of the BBs was carried out in a similar manner. The final series was constructed by merging different BB series. We modelled the propagation of errors straightforwardly with Monte Carlo simulations. A potential bias due to the selection of BBs was investigated and the effect was shown to lie within the 1σ interval of the produced series. The exact selection of the reference period was shown to have a rather small effect on our calibration as well. Results: The final series extends back to 1739 and includes data from 314 observers. This series suggests moderate activity during the 18th and 19th century, which is significantly lower than the high level of solar activity predicted by other recent reconstructions applying linear regressions. Conclusions: The new series provides a robust reconstruction, based on modern and non-parametric methods, of sunspot group numbers since 1739, and it confirms the existence of the modern grand maximum of solar

Semi-empirical model for prediction of unsteady forces on an airfoil with application to flutter

Science.gov (United States)

Mahajan, A. J.; Kaza, K. R. V.; Dowell, E. H.

1993-01-01

A semi-empirical model is described for predicting unsteady aerodynamic forces on arbitrary airfoils under mildly stalled and unstalled conditions. Aerodynamic forces are modeled using second order ordinary differential equations for lift and moment with airfoil motion as the input. This model is simultaneously integrated with structural dynamics equations to determine flutter characteristics for a two degrees-of-freedom system. Results for a number of cases are presented to demonstrate the suitability of this model to predict flutter. Comparison is made to the flutter characteristics determined by a Navier-Stokes solver and also the classical incompressible potential flow theory.

Long-term variations in the geomagnetic activity level Part II: Ascending phases of sunspot cycles

Directory of Open Access Journals (Sweden)

V. Mussino

1994-08-01

Full Text Available Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (r between geomagnetic indices and sunspot numbers for the ascending phases of sunspot cycles 9 to 22, confirming previous findings based on a minor number of sunspot cycles. The result is useful to researchers in topics related to solar-terrestrial physics, particularly for the interpretation of long-term trends in geomagnetic activity during the past, and to forecast geomagnetic activity levels in the future.

The Earth's Interaction With the Sun Over the Millennia From Analyses of Historical Sunspot, Auroral and Climate Records

Science.gov (United States)

Yau, K.

2001-12-01

spell, dated to {ca} 700 by Dansgaard [{Nature} {255}, 1974, 24]. Using records of advances and retreats of glaciers, previous researchers have linked it to a cold spell in the previous two centuries instead, thus requiring an offset in timescales. Our literature search has yielded more records of sunspot sightings, and established the fifth century as a minimum of solar activity, ending in a maximum at {ca} 500. These features and the minimum at 700 match contemporary deviations of atmospheric C 14 from a secular trend, due primarily to long-term changes in the strength of the Earth's magnetic moment [Stuiver, {Radiocarbon} {35}, 215]. Pang has shown that the climate of Eurasia was cold in the 5th century, due partly to volcanic cooling [{Eos} {80}, #46, 1999, F220]. Reduced solar luminosity may have contributed to that too. The cold apparently forced massive southward migrations of Teutonic and Asian barbarians into the Roman Empire, ending it in 476. Europe was plunged into the Dark Age, from which it did not recover until the climate warmed up again toward the end of the millennium. Finally, climate changes can also be produced by greenhouse warming, reorganization of ocean current systems "Dansgaard-Oeschger events," the Earth's orbital variations "Milankovitch effects," {etc}. Continued analysis of historical records, in conjunction with other proxy data, can help shed light on the nature of the Earth's interactions with the Sun, and the causes of past climate changes.

COMPARISON OF CHAOTIC AND FRACTAL PROPERTIES OF POLAR FACULAE WITH SUNSPOT ACTIVITY

Energy Technology Data Exchange (ETDEWEB)

Deng, L. H.; Xiang, Y. Y.; Dun, G. T. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216 (China); Li, B., E-mail: wooden@escience.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University at Weihai, Weihai 264209 (China)

2016-01-15

The solar magnetic activity is governed by a complex dynamo mechanism and exhibits a nonlinear dissipation behavior in nature. The chaotic and fractal properties of solar time series are of great importance to understanding the solar dynamo actions, especially with regard to the nonlinear dynamo theories. In the present work, several nonlinear analysis approaches are proposed to investigate the nonlinear dynamical behavior of the polar faculae and sunspot activity for the time interval from 1951 August to 1998 December. The following prominent results are found: (1) both the high- and the low-latitude solar activity are governed by a three-dimensional chaotic attractor, and the chaotic behavior of polar faculae is the most complex, followed by that of the sunspot areas, and then the sunspot numbers; (2) both the high- and low-latitude solar activity exhibit a high degree of persistent behavior, and their fractal nature is due to such long-range correlation; (3) the solar magnetic activity cycle is predictable in nature, but the high-accuracy prediction should only be done for short- to mid-term due to its intrinsically dynamical complexity. With the help of the Babcock–Leighton dynamo model, we suggest that the nonlinear coupling of the polar magnetic fields with strong active-region fields exhibits a complex manner, causing the statistical similarities and differences between the polar faculae and the sunspot-related indicators.

A semi empirical formula for the angular differential number albedo of low-energy photons

Directory of Open Access Journals (Sweden)

Marković Srpko

2005-01-01

Full Text Available Low-energy photon reflection from water, aluminum, and iron is simulated by the MCNP code and results are com pared with similar Monte Carlo calculations. For the energy range from 60 to 150 keV and for the normal incidence of initial photons, a universal shape of the normalized angular differential number albedo is observed and after that fitted by the curve fit ting procedure in form of a second order polynomial over the polar angle. Finally, a one-parameter formula for the angular differential number albedo is developed and verified for water through the comparison of results with the semi empirical formulae and Monte Carlo calculations of other authors.

Normalization of time-series satellite reflectance data to a standard sun-target-sensor geometry using a semi-empirical model

Science.gov (United States)

Zhao, Yongguang; Li, Chuanrong; Ma, Lingling; Tang, Lingli; Wang, Ning; Zhou, Chuncheng; Qian, Yonggang

2017-10-01

Time series of satellite reflectance data have been widely used to characterize environmental phenomena, describe trends in vegetation dynamics and study climate change. However, several sensors with wide spatial coverage and high observation frequency are usually designed to have large field of view (FOV), which cause variations in the sun-targetsensor geometry in time-series reflectance data. In this study, on the basis of semiempirical kernel-driven BRDF model, a new semi-empirical model was proposed to normalize the sun-target-sensor geometry of remote sensing image. To evaluate the proposed model, bidirectional reflectance under different canopy growth conditions simulated by Discrete Anisotropic Radiative Transfer (DART) model were used. The semi-empirical model was first fitted by using all simulated bidirectional reflectance. Experimental result showed a good fit between the bidirectional reflectance estimated by the proposed model and the simulated value. Then, MODIS time-series reflectance data was normalized to a common sun-target-sensor geometry by the proposed model. The experimental results showed the proposed model yielded good fits between the observed and estimated values. The noise-like fluctuations in time-series reflectance data was also reduced after the sun-target-sensor normalization process.

Semi-empirical fragmentation model of meteoroid motion and radiation during atmospheric penetration

Science.gov (United States)

Revelle, D. O.; Ceplecha, Z.

2002-11-01

A semi-empirical fragmentation model (FM) of meteoroid motion, ablation, and radiation including two types of fragmentation is outlined. The FM was applied to observational data (height as function of time and the light curve) of Lost City, Innisfree and Benešov bolides. For the Lost City bolide we were able to fit the FM to the observed height as function of time with ±13 m and to the observed light curve with ±0.17 magnitude. Corresponding numbers for Innisfree are ±25 m and ±0.14 magnitude, and for Benešov ±46 m and ±0.19 magnitude. We also define apparent and intrinsic values of σ, K, and τ. Using older results and our fit of FM to the Lost City bolide we derived corrections to intrinsic luminous efficiencies expressed as functions of velocity, mass, and normalized air density.

Aurorae, sunspots and weather, mainly since A.D. 1200

International Nuclear Information System (INIS)

Schove, D.J.

1981-01-01

Auroral records recieved for the Spectrum of Time project were used in 1955 to estimate sunspot activity and the dates maxima and minima back to 649 B.C. An additional set of rules has been developed and has made possible further improvements utilizing the separate auroral maxima associated with flares and coronal holes on the sun. A further set can now be given. 1) The time between sunspot maxima depends especially on the ratio of the amplitudes: the time between minima is high if the next cycle is very weak and low when the two consecutive cycles are both strong. 2) The time of rise is usually dependent on the strength of the next maxima, and the time of fall is low when a moderate cycle is followed by a strong one. (orig./WL)

Absorption of acoustic waves by sunspots. II - Resonance absorption in axisymmetric fibril models

Science.gov (United States)

Rosenthal, C. S.

1992-01-01

Analytical calculations of acoustic waves scattered by sunspots which concentrate on the absorption at the magnetohydrodynamic Alfven resonance are extended to the case of a flux-tube embedded in a uniform atmosphere. The model is based on a flux-tubes of varying radius that are highly structured, translationally invariant, and axisymmetric. The absorbed fractional energy is determined for different flux-densities and subphotospheric locations with attention given to the effects of twist. When the flux is highly concentrated into annuli efficient absorption is possible even when the mean magnetic flux density is low. The model demonstrates low absorption at low azimuthal orders even in the presence of twist which generally increases the range of wave numbers over which efficient absorption can occur. Resonance absorption is concluded to be an efficient mechanism in monolithic sunspots, fibril sunspots, and plage fields.

On the determination of heliographic positions and rotation velocities of sunspots. Pt. 2

International Nuclear Information System (INIS)

Balthasar, H.

1983-01-01

Using sunspot positions of small sunspots observed at Debrecen and Locarno as well as positions of recurrent sunspots taken from the Greenwich Photoheliographic Results (1940-1976) the influence of the Wilson depression on the rotation velocities was investigated. It was found that the Wilson depression can be determined by minimizing errors of the rotation velocities or minimizing the differences of rotation velocities determined from disk passages and central meridian passages. The Wilson depressions found were between 765 km and 2500 km for the first sample while they were between 0 km and several 1000 km for the second sample. The averaged Wilson depression for the second sample is between 500 km and 965 km depending on the reduction method. A dependence of the Wilson depression on the age of the spots investigated seems not to exist. (orig.)

Application of the Markov chain approximation to the sunspot observations

International Nuclear Information System (INIS)

Onal, M.

1988-01-01

The positions of the 13,588 sunspot groups observed during the cycle of 1950-1960 at the Istanbul University Observatory have been corrected for the effect of differential rotation. The evolution probability of a sunspot group to the other one in the same region have been determined. By using the Markov chain approximation, the types of these groups and their transition probabilities during the following activity cycle (1950-1960), and the concentration of active regions during 1950-1960 have been estimated. The transition probabilities from the observations of the activity cycle 1960-1970 have been compared with the predicted transition probabilities and a good correlation has been noted. 5 refs.; 2 tabs

MODELING THE CHROMOSPHERE OF A SUNSPOT AND THE QUIET SUN

Energy Technology Data Exchange (ETDEWEB)

Avrett, E.; Tian, H. [Smithsonian Astrophysical Observatory, Cambridge, MA 02138 (United States); Landi, E. [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Curdt, W. [Max Planck Institut für Sonnensystemfoschung, Goettingen (Germany); Wülser, J.-P. [Lockheed Martin Advanced Techonology Center (United States)

2015-10-01

Semiempirical atmospheric modeling attempts to match an observed spectrum by finding the temperature distribution and other physical parameters along the line of sight through the emitting region such that the calculated spectrum agrees with the observed one. In this paper we take the observed spectrum of a sunspot and the quiet Sun in the EUV wavelength range 668–1475 Å from the 2001 SUMER atlas of Curdt et al. to determine models of the two atmospheric regions, extending from the photosphere through the overlying chromosphere into the transition region. We solve the coupled statistical equilibrium and optically thick radiative transfer equations for a set of 32 atoms and ions. The atoms that are part of molecules are treated separately, and are excluded from the atomic abundances and atomic opacities. We compare the Mg ii k line profile observations from the Interface Region Imaging Spectrograph with the profiles calculated from the two models. The calculated profiles for the sunspot are substantially lower than the observed ones, based on the SUMER models. The only way we have found to raise the calculated Mg ii lines to agree with the observations is to introduce illumination of the sunspot from the surrounding active region.

Denoising of chaotic signal using independent component analysis and empirical mode decomposition with circulate translating

International Nuclear Information System (INIS)

Wang Wen-Bo; Zhang Xiao-Dong; Chang Yuchan; Wang Xiang-Li; Wang Zhao; Chen Xi; Zheng Lei

2016-01-01

In this paper, a new method to reduce noises within chaotic signals based on ICA (independent component analysis) and EMD (empirical mode decomposition) is proposed. The basic idea is decomposing chaotic signals and constructing multidimensional input vectors, firstly, on the base of EMD and its translation invariance. Secondly, it makes the independent component analysis on the input vectors, which means that a self adapting denoising is carried out for the intrinsic mode functions (IMFs) of chaotic signals. Finally, all IMFs compose the new denoised chaotic signal. Experiments on the Lorenz chaotic signal composed of different Gaussian noises and the monthly observed chaotic sequence on sunspots were put into practice. The results proved that the method proposed in this paper is effective in denoising of chaotic signals. Moreover, it can correct the center point in the phase space effectively, which makes it approach the real track of the chaotic attractor. (paper)

LONG-TERM MEASUREMENTS OF SUNSPOT MAGNETIC TILT ANGLES

Energy Technology Data Exchange (ETDEWEB)

Li Jing [Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095-1567 (United States); Ulrich, Roger K., E-mail: jli@igpp.ucla.edu [Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, CA 90095-1567 (United States)

2012-10-20

Tilt angles of close to 30,600 sunspots are determined using Mount Wilson daily averaged magnetograms taken from 1974 to 2012, and SOHO/MDI magnetograms taken from 1996 to 2010. Within a cycle, more than 90% of sunspots have a normal polarity alignment along the east-west direction following Hale's law. The median tilts increase with increasing latitude (Joy's law) at a rate of {approx}0.{sup 0}5 per degree of latitude. Tilt angles of spots appear largely invariant with respect to time at a given latitude, but they decrease by {approx}0.{sup 0}9 per year on average, a trend that largely reflects Joy's law following the butterfly diagram. We find an asymmetry between the hemispheres in the mean tilt angles. On average, the tilts are greater in the Southern than in the Northern Hemisphere for all latitude zones, and the differences increase with increasing latitude.

CHROMOSPHERIC SUNSPOTS IN THE MILLIMETER RANGE AS OBSERVED BY THE NOBEYAMA RADIOHELIOGRAPH

Energy Technology Data Exchange (ETDEWEB)

Iwai, Kazumasa [National Institute of Information and Communications Technology, Koganei 184-8795, Tokyo (Japan); Koshiishi, Hideki [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, Tsukuba 305-8505 (Japan); Shibasaki, Kiyoto [Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Nagano 384-1305 (Japan); Nozawa, Satoshi; Miyawaki, Shun; Yoneya, Takuro, E-mail: kazumasa.iwai@nict.go.jp [Department of Science, Ibaraki University, Mito, Ibaraki 310-8512 (Japan)

2016-01-10

We investigate the upper chromosphere and the transition region of the sunspot umbra using the radio brightness temperature at 34 GHz (corresponding to 8.8 mm observations) as observed by the Nobeyama Radioheliograph (NoRH). Radio free–free emission in the longer millimeter range is generated around the transition region, and its brightness temperature yields the region's temperature and density distribution. We use the NoRH data at 34 GHz by applying the Steer-CLEAN image synthesis. These data and the analysis method enable us to investigate the chromospheric structures in the longer millimeter range with high spatial resolution and sufficient visibilities. We also perform simultaneous observations of one sunspot using the NoRH and the Nobeyama 45 m telescope operating at 115 GHz. We determine that 115 GHz emission mainly originates from the lower chromosphere while 34 GHz emission mainly originates from the upper chromosphere and transition region. These observational results are consistent with the radio emission characteristics estimated from current atmospheric models of the chromosphere. On the other hand, the observed brightness temperature of the umbral region is almost the same as that of the quiet region. This result is inconsistent with current sunspot models, which predict a considerably higher brightness temperature of the sunspot umbra at 34 GHz. This inconsistency suggests that the temperature of the region at which the 34 GHz radio emission becomes optically thick should be lower than that predicted by the models.

The effect of electrodes on 11 acene molecular spin valve: Semi-empirical study

Science.gov (United States)

Aadhityan, A.; Preferencial Kala, C.; John Thiruvadigal, D.

2017-10-01

A new revolution in electronics is molecular spintronics, with the contemporary evolution of the two novel disciplines of spintronics and molecular electronics. The key point is the creation of molecular spin valve which consists of a diamagnetic molecule in between two magnetic leads. In this paper, non-equilibrium Green's function (NEGF) combined with Extended Huckel Theory (EHT); a semi-empirical approach is used to analyse the electron transport characteristics of 11 acene molecular spin valve. We examine the spin-dependence transport on 11 acene molecular junction with various semi-infinite electrodes as Iron, Cobalt and Nickel. To analyse the spin-dependence transport properties the left and right electrodes are joined to the central region in parallel and anti-parallel configurations. We computed spin polarised device density of states, projected device density of states of carbon and the electrode element, and transmission of these devices. The results demonstrate that the effect of electrodes modifying the spin-dependence behaviours of these systems in a controlled way. In Parallel and anti-parallel configuration the separation of spin up and spin down is lager in the case of iron electrode than nickel and cobalt electrodes. It shows that iron is the best electrode for 11 acene spin valve device. Our theoretical results are reasonably impressive and trigger our motivation for comprehending the transport properties of these molecular-sized contacts.

Semi-empirical models for the estimation of clear sky solar global and direct normal irradiances in the tropics

International Nuclear Information System (INIS)

Janjai, S.; Sricharoen, K.; Pattarapanitchai, S.

2011-01-01

Highlights: → New semi-empirical models for predicting clear sky irradiance were developed. → The proposed models compare favorably with other empirical models. → Performance of proposed models is comparable with that of widely used physical models. → The proposed models have advantage over the physical models in terms of simplicity. -- Abstract: This paper presents semi-empirical models for estimating global and direct normal solar irradiances under clear sky conditions in the tropics. The models are based on a one-year period of clear sky global and direct normal irradiances data collected at three solar radiation monitoring stations in Thailand: Chiang Mai (18.78 o N, 98.98 o E) located in the North of the country, Nakhon Pathom (13.82 o N, 100.04 o E) in the Centre and Songkhla (7.20 o N, 100.60 o E) in the South. The models describe global and direct normal irradiances as functions of the Angstrom turbidity coefficient, the Angstrom wavelength exponent, precipitable water and total column ozone. The data of Angstrom turbidity coefficient, wavelength exponent and precipitable water were obtained from AERONET sunphotometers, and column ozone was retrieved from the OMI/AURA satellite. Model validation was accomplished using data from these three stations for the data periods which were not included in the model formulation. The models were also validated against an independent data set collected at Ubon Ratchathani (15.25 o N, 104.87 o E) in the Northeast. The global and direct normal irradiances calculated from the models and those obtained from measurements are in good agreement, with the root mean square difference (RMSD) of 7.5% for both global and direct normal irradiances. The performance of the models was also compared with that of other models. The performance of the models compared favorably with that of empirical models. Additionally, the accuracy of irradiances predicted from the proposed model are comparable with that obtained from some

Relationship between geomagnetic classes’ activity phases and their occurrence during the sunspot cycle

Directory of Open Access Journals (Sweden)

Frédéric Ouattara

2009-06-01

Full Text Available Four well known geomagnetic classes of activity such as quiet days activity, fluctuating activity, recurrent activity
and shock activity time occurrences have been determined not only by using time profile of sunspot number
Rz but also by using aa index values.
We show that recurrent wind stream activity and fluctuating activity occur in opposite phase and slow solar wind
activity during minimum phase and shock activity at the maximum phase.
It emerges from this study that fluctuating activity precedes the sunspot cycle by π/2 and the latter also precedes
recurrent activity by π/2. Thus in the majority the activities do not happen at random; the sunspot cycle starts
with quiet days activity, continues with fluctuating activity and during its maximum phase arrives shock activity.
The descending phase is characterized by the manifestation of recurrent wind stream activity.

Constructive Verification, Empirical Induction, and Falibilist Deduction: A Threefold Contrast

Directory of Open Access Journals (Sweden)

Julio Michael Stern

2011-10-01

Full Text Available This article explores some open questions related to the problem of verification of theories in the context of empirical sciences by contrasting three epistemological frameworks. Each of these epistemological frameworks is based on a corresponding central metaphor, namely: (a Neo-empiricism and the gambling metaphor; (b Popperian falsificationism and the scientific tribunal metaphor; (c Cognitive constructivism and the object as eigen-solution metaphor. Each of one of these epistemological frameworks has also historically co-evolved with a certain statistical theory and method for testing scientific hypotheses, respectively: (a Decision theoretic Bayesian statistics and Bayes factors; (b Frequentist statistics and p-values; (c Constructive Bayesian statistics and e-values. This article examines with special care the Zero Probability Paradox (ZPP, related to the verification of sharp or precise hypotheses. Finally, this article makes some remarks on Lakatos’ view of mathematics as a quasi-empirical science.

An empirical analysis of strategy implementation process and performance of construction companies

Science.gov (United States)

Zaidi, F. I.; Zawawi, E. M. A.; Nordin, R. M.; Ahnuar, E. M.

2018-02-01

Strategy implementation is known as action stage where it is to be considered as the most difficult stage in strategic planning. Strategy implementation can influence the whole texture of a company including its performance. The aim of this research is to provide the empirical relationship between strategy implementation process and performance of construction companies. This research establishes the strategy implementation process and how it influences the performance of construction companies. This research used quantitative method approached via questionnaire survey. Respondents were G7 construction companies in Klang Valley, Selangor. Pearson correlation analysis indicate a strong positive relationship between strategy implementation process and construction companies’ performance. The most importance part of strategy implementation process is to provide sufficient training for employees which directly influence the construction companies’ profit growth and employees’ growth. This research results will benefit top management in the construction companies to conduct strategy implementation in their companies. This research may not reflect the whole construction industry in Malaysia. Future research may be resumed to small and medium grades contractors and perhaps in other areas in Malaysia.

Development and empirical validation of symmetric component measures of multidimensional constructs: customer and competitor orientation.

Science.gov (United States)

Sørensen, Hans Eibe; Slater, Stanley F

2008-08-01

Atheoretical measure purification may lead to construct deficient measures. The purpose of this paper is to provide a theoretically driven procedure for the development and empirical validation of symmetric component measures of multidimensional constructs. Particular emphasis is placed on establishing a formalized three-step procedure for achieving a posteriori content validity. Then the procedure is applied to development and empirical validation of two symmetrical component measures of market orientation, customer orientation and competitor orientation. Analysis suggests that average variance extracted is particularly critical to reliability in the respecification of multi-indicator measures. In relation to this, the results also identify possible deficiencies in using Cronbach alpha for establishing reliable and valid measures.

Semi-empirical model for retrieval of soil moisture using RISAT-1 C-Band SAR data over a sub-tropical semi-arid area of Rewari district, Haryana (India)

Science.gov (United States)

Rawat, Kishan Singh; Sehgal, Vinay Kumar; Pradhan, Sanatan; Ray, Shibendu S.

2018-03-01

We have estimated soil moisture (SM) by using circular horizontal polarization backscattering coefficient (σ o_{RH}), differences of circular vertical and horizontal σ o (σ o_{RV} {-} σ o_{RH}) from FRS-1 data of Radar Imaging Satellite (RISAT-1) and surface roughness in terms of RMS height ({RMS}_{height}). We examined the performance of FRS-1 in retrieving SM under wheat crop at tillering stage. Results revealed that it is possible to develop a good semi-empirical model (SEM) to estimate SM of the upper soil layer using RISAT-1 SAR data rather than using existing empirical model based on only single parameter, i.e., σ o. Near surface SM measurements were related to σ o_{RH}, σ o_{RV} {-} σ o_{RH} derived using 5.35 GHz (C-band) image of RISAT-1 and {RMS}_{height}. The roughness component derived in terms of {RMS}_{height} showed a good positive correlation with σ o_{RV} {-} σ o_{RH} (R2 = 0.65). By considering all the major influencing factors (σ o_{RH}, σ o_{RV} {-} σ o_{RH}, and {RMS}_{height}), an SEM was developed where SM (volumetric) predicted values depend on σ o_{RH}, σ o_{RV} {-} σ o_{RH}, and {RMS}_{height}. This SEM showed R2 of 0.87 and adjusted R2 of 0.85, multiple R=0.94 and with standard error of 0.05 at 95% confidence level. Validation of the SM derived from semi-empirical model with observed measurement ({SM}_{Observed}) showed root mean square error (RMSE) = 0.06, relative-RMSE (R-RMSE) = 0.18, mean absolute error (MAE) = 0.04, normalized RMSE (NRMSE) = 0.17, Nash-Sutcliffe efficiency (NSE) = 0.91 ({≈ } 1), index of agreement (d) = 1, coefficient of determination (R2) = 0.87, mean bias error (MBE) = 0.04, standard error of estimate (SEE) = 0.10, volume error (VE) = 0.15, variance of the distribution of differences ({S}d2) = 0.004. The developed SEM showed better performance in estimating SM than Topp empirical model which is based only on σ o. By using the developed SEM, top soil SM can be estimated with low mean absolute

Comparative empirical analysis of temporal relationships between construction investment and economic growth in the United States

Directory of Open Access Journals (Sweden)

Navid Ahmadi

2017-09-01

Full Text Available The majority of policymakers believe that investments in construction infrastructure would boost the economy of the United States (U.S.. They also assume that construction investment in infrastructure has similar impact on the economies of different U.S. states. In contrast, there have been studies showing the negative impact of construction activities on the economy. However, there has not been any research attempt to empirically test the temporal relationships between construction investment and economic growth in the U.S. states, to determine the longitudinal impact of construction investment on the economy of each state. The objective of this study is to investigate whether Construction Value Added (CVA is the leading (or lagging indicator of real Gross Domestic Product (real GDP for every individual state of the U.S. using empirical time series tests. The results of Granger causality tests showed that CVA is a leading indicator of state real GDP in 18 states and the District of Columbia; real GDP is a leading indicator of CVA in 10 states and the District of Columbia. There is a bidirectional relationship between CVA and real GDP in 5 states and the District of Columbia. In 8 states and the District of Columbia, not only do CVA and real GDP have leading/lagging relationships, but they are also cointegrated. These results highlight the important role of the construction industry in these states. The results also show that leading (or lagging lengths vary for different states. The results of the comparative empirical analysis reject the hypothesis that CVA is a leading indicator of real GDP in the states with the highest shares of construction in the real GDP. The findings of this research contribute to the state of knowledge by quantifying the temporal relationships between construction investment and economic growth in the U.S. states. It is expected that the results help policymakers better understand the impact of construction investment

Integrative gene network construction to analyze cancer recurrence using semi-supervised learning.

Science.gov (United States)

Park, Chihyun; Ahn, Jaegyoon; Kim, Hyunjin; Park, Sanghyun

2014-01-01

The prognosis of cancer recurrence is an important research area in bioinformatics and is challenging due to the small sample sizes compared to the vast number of genes. There have been several attempts to predict cancer recurrence. Most studies employed a supervised approach, which uses only a few labeled samples. Semi-supervised learning can be a great alternative to solve this problem. There have been few attempts based on manifold assumptions to reveal the detailed roles of identified cancer genes in recurrence. In order to predict cancer recurrence, we proposed a novel semi-supervised learning algorithm based on a graph regularization approach. We transformed the gene expression data into a graph structure for semi-supervised learning and integrated protein interaction data with the gene expression data to select functionally-related gene pairs. Then, we predicted the recurrence of cancer by applying a regularization approach to the constructed graph containing both labeled and unlabeled nodes. The average improvement rate of accuracy for three different cancer datasets was 24.9% compared to existing supervised and semi-supervised methods. We performed functional enrichment on the gene networks used for learning. We identified that those gene networks are significantly associated with cancer-recurrence-related biological functions. Our algorithm was developed with standard C++ and is available in Linux and MS Windows formats in the STL library. The executable program is freely available at: http://embio.yonsei.ac.kr/~Park/ssl.php.

Integrative gene network construction to analyze cancer recurrence using semi-supervised learning.

Directory of Open Access Journals (Sweden)

Chihyun Park

Full Text Available BACKGROUND: The prognosis of cancer recurrence is an important research area in bioinformatics and is challenging due to the small sample sizes compared to the vast number of genes. There have been several attempts to predict cancer recurrence. Most studies employed a supervised approach, which uses only a few labeled samples. Semi-supervised learning can be a great alternative to solve this problem. There have been few attempts based on manifold assumptions to reveal the detailed roles of identified cancer genes in recurrence. RESULTS: In order to predict cancer recurrence, we proposed a novel semi-supervised learning algorithm based on a graph regularization approach. We transformed the gene expression data into a graph structure for semi-supervised learning and integrated protein interaction data with the gene expression data to select functionally-related gene pairs. Then, we predicted the recurrence of cancer by applying a regularization approach to the constructed graph containing both labeled and unlabeled nodes. CONCLUSIONS: The average improvement rate of accuracy for three different cancer datasets was 24.9% compared to existing supervised and semi-supervised methods. We performed functional enrichment on the gene networks used for learning. We identified that those gene networks are significantly associated with cancer-recurrence-related biological functions. Our algorithm was developed with standard C++ and is available in Linux and MS Windows formats in the STL library. The executable program is freely available at: http://embio.yonsei.ac.kr/~Park/ssl.php.

Semi top-down method combined with earth-bank, an effective method for basement construction.

Science.gov (United States)

Tuan, B. Q.; Tam, Ng M.

2018-04-01

Choosing an appropriate method of deep excavation not only plays a decisive role in technical success, but also in economics of the construction project. Presently, we mainly base on to key methods: “Bottom-up” and “Top-down” construction method. Right now, this paper presents an another method of construction that is “Semi Top-down method combining with earth-bank” in order to take the advantages and limit the weakness of the above methods. The Bottom-up method was improved by using the earth-bank to stabilize retaining walls instead of the bracing steel struts. The Top-down method was improved by using the open cut method for the half of the earthwork quantities.

Molecular Diagnostics of the Internal Structure of Starspots and Sunspots

Science.gov (United States)

Afram, N.; Berdyugina, S. V.; Fluri, D. M.; Solanki, S. K.; Lagg, A.; Petit, P.; Arnaud, J.

2006-12-01

We have analyzed the usefulness of molecules as a diagnostic tool for studying solar and stellar magnetism with the molecular Zeeman and Paschen-Back effects. In the first part we concentrate on molecules that are observed in sunspots such as MgH and TiO. We present calculated molecular line profiles obtained by assuming magnetic fields of 2-3 kG and compare these synthetic Stokes profiles with spectro-polarimetric observations in sunspots. The good agreement between the theory and observations allows us to turn our attention in the second part to starspots to gain insight into their internal structure. We investigate the temperature range in which the selected molecules can serve as indicators for magnetic fields on highly active cool stars and compare synthetic Stokes profiles with our recent observations.

a Semi-Empirical Topographic Correction Model for Multi-Source Satellite Images

Science.gov (United States)

Xiao, Sa; Tian, Xinpeng; Liu, Qiang; Wen, Jianguang; Ma, Yushuang; Song, Zhenwei

2018-04-01

Topographic correction of surface reflectance in rugged terrain areas is the prerequisite for the quantitative application of remote sensing in mountainous areas. Physics-based radiative transfer model can be applied to correct the topographic effect and accurately retrieve the reflectance of the slope surface from high quality satellite image such as Landsat8 OLI. However, as more and more images data available from various of sensors, some times we can not get the accurate sensor calibration parameters and atmosphere conditions which are needed in the physics-based topographic correction model. This paper proposed a semi-empirical atmosphere and topographic corrction model for muti-source satellite images without accurate calibration parameters.Based on this model we can get the topographic corrected surface reflectance from DN data, and we tested and verified this model with image data from Chinese satellite HJ and GF. The result shows that the correlation factor was reduced almost 85 % for near infrared bands and the classification overall accuracy of classification increased 14 % after correction for HJ. The reflectance difference of slope face the sun and face away the sun have reduced after correction.

Records of auroral candidates and sunspots in Rikkokushi, chronicles of ancient Japan from early 7th century to 887

Science.gov (United States)

Hayakawa, Hisashi; Iwahashi, Kiyomi; Tamazawa, Harufumi; Ebihara, Yusuke; Kawamura, Akito Davis; Isobe, Hiroaki; Namiki, Katsuko; Shibata, Kazunari

2017-12-01

We present the results of the surveys on sunspots and auroral candidates in Rikkokushi, Japanese official histories from the early 7th century to 887, to review the solar and auroral activities. In total, we found one sunspot record and 13 auroral candidates in Rikkokushi. We then examine the records of the sunspots and auroral candidates, compare the auroral candidates with the lunar phase to estimate their reliability, and compare the records of the sunspots and auroral candidates with the contemporary total solar irradiance reconstructed from radioisotope data. We also identify the locations of the observational sites to review possible equatorward expansion of the auroral oval. These discussions suggest a major gap in auroral candidates from the late 7th to early 9th centuries, which includes the candidate of the grand minimum reconstructed from the radioisotope data, a similar tendency as the distributions of sunspot records in contemporary China, and a relatively high magnetic latitude of observational sites with a higher potential for observing aurorae more frequently than at present.

Construction and use of an optical semi-automatic titrator employing the technique of reflectance photometry

International Nuclear Information System (INIS)

Hwang, Hoon

2001-01-01

An optical semi-automatic titrator was constructed employing the technique of the reflectance spectrometry and was tested for the determination of the end points of the acid-base, precipitation, and EDTA titrations. And since the current optical semi-automatic titrator built on the principle of the reflectance spectrometry could be successfully used even for the determination of the end of the end point in the precipitation titration where the solid particles are formed during the titration process, it was found to be feasible that a completely automated optical titrator would be designed and built based on the current findings

Design and construction of a vertical hydroponic system with semi-continuous and continuous nutrient cycling

Science.gov (United States)

Siswanto, Dian; Widoretno, Wahyu

2017-11-01

Problems due to the increase in agricultural land use change can be solved by hydroponic system applications. Many hydroponic studies have been conducted in several countries while their applications in Indonesia requires modification and adjustment. This research was conducted to design and construct a hydroponic system with semi-continuous and continuous nutrition systems. The hydroponic system which was used adapts the ebb and flow system, and the nutrient film technique (NFT). This hydroponic system was made from polyvinyl chloride (PVC) pipes with a length of 197 cm, a diameter of 16 cm, and a slope of 4°. It was constructed from four PVC pipes. In semi-continuous irrigation treatment, nutrients flow four to six times for each of ten minutes depending on plant development and the estimated evapotranspiration occurring, while in a continuous nutrient system the nutrients are streamed for twenty-four hours without stopping at a maximum flow rate of 13.7 L per second.

Semi-empirical spectrophotometric (SESp) method for the indirect determination of the ratio of cationic micellar binding constants of counterions X⁻ and Br⁻(K(X)/K(Br)).

Science.gov (United States)

Khan, Mohammad Niyaz; Yusof, Nor Saadah Mohd; Razak, Norazizah Abdul

2013-01-01

The semi-empirical spectrophotometric (SESp) method, for the indirect determination of ion exchange constants (K(X)(Br)) of ion exchange processes occurring between counterions (X⁻ and Br⁻) at the cationic micellar surface, is described in this article. The method uses an anionic spectrophotometric probe molecule, N-(2-methoxyphenyl)phthalamate ion (1⁻), which measures the effects of varying concentrations of inert inorganic or organic salt (Na(v)X, v = 1, 2) on absorbance, (A(ob)) at 310 nm, of samples containing constant concentrations of 1⁻, NaOH and cationic micelles. The observed data fit satisfactorily to an empirical equation which gives the values of two empirical constants. These empirical constants lead to the determination of K(X)(Br) (= K(X)/K(Br) with K(X) and K(Br) representing cationic micellar binding constants of counterions X and Br⁻). This method gives values of K(X)(Br) for both moderately hydrophobic and hydrophilic X⁻. The values of K(X)(Br), obtained by using this method, are comparable with the corresponding values of K(X)(Br), obtained by the use of semi-empirical kinetic (SEK) method, for different moderately hydrophobic X. The values of K(X)(Br) for X = Cl⁻ and 2,6-Cl₂C6H₃CO₂⁻, obtained by the use of SESp and SEK methods, are similar to those obtained by the use of other different conventional methods.

Occurrences of flares with type II and IV radio events in interacting sunspot groups in the course of revolutions

International Nuclear Information System (INIS)

Klimes, J.; Krivsky, L.

1984-01-01

Using data from 11-year solar cycle No. 20, it was found that flares with type II radio bursts are more than twice as frequent and flares with type IV bursts nearly twice as frequent in sunspot groups which developed close to each other or which merged in the course of revolutions than in isolated sunspot groups. With both types the occurrence of these flares is concentrated in the revolution of the so-called sunspot group interaction (their approximation, merging). (author)

Visual Circular Analysis of 266 Years of Sunspot Counts.

Science.gov (United States)

Buelens, Bart

2016-06-01

Sunspots, colder areas that are visible as dark spots on the surface of the Sun, have been observed for centuries. Their number varies with a period of ∼11 years, a phenomenon closely related to the solar activity cycle. Recently, observation records dating back to 1749 have been reassessed, resulting in the release of a time series of sunspot numbers covering 266 years of observations. This series is analyzed using circular analysis to determine the periodicity of the occurrence of solar maxima. The circular analysis is combined with spiral graphs to provide a single visualization, simultaneously showing the periodicity of the series, the degree to which individual cycle lengths deviate from the average period, and differences in levels reached during the different maxima. This type of visualization of cyclic time series with varying cycle lengths in which significant events occur periodically is broadly applicable. It is aimed particularly at science communication, education, and public outreach.

Historical evidence concerning the Sun: interpretation of sunspot records during the telescopic and pretelescopic eras

International Nuclear Information System (INIS)

Stephenson, F.R.

1990-01-01

The value of sunspot observations in investigating solar activity trends - mainly on the centennial to millennial timescale - is considered in some detail. It is shown that although observations made since the mid-eighteenth century are in general very reliable indicators of solar activity, older data are of dubious quality and utility. The sunspot record in both the pretelescopic and early telescopic periods appears to be confused by serious data artefacts. (author)

New semi-empirical formula for α-decay half-lives of the heavy and superheavy nuclei

Energy Technology Data Exchange (ETDEWEB)

Manjunatha, H.C. [Government College for Women, Department of Physics, Kolar, Karnataka (India); Sridhar, K.N. [Government First Grade College, Department of Physics, Kolar, Karnataka (India)

2017-07-15

We have succesfully formulated the semi-empirical formula for α-decay half-lives of heavy and superheavy nuclei for different isotopes of the wide atomic-number range 94 < Z < 136. We have considered 2627 isotopes of heavy and superheavy nuclei for the fitting. The value produced by the present formula is compared with that of experiments and other eleven models, i.e. ImSahu, Sahu, Royer10, VS2, UNIV2, SemFIS2, WKB. Sahu16, Densov, VSS and Royer formula. This formula is exclusively for heavy and superheavy nuclei. α-decay is one of the dominant decay mode of superheavy nucleus. By identifying the α-decay mode superheavy nuclei can be detected. This formula helps in predicting the α-decay chains of superheavy nuclei. (orig.)

Regular graph construction for semi-supervised learning

International Nuclear Information System (INIS)

Vega-Oliveros, Didier A; Berton, Lilian; Eberle, Andre Mantini; Lopes, Alneu de Andrade; Zhao, Liang

2014-01-01

Semi-supervised learning (SSL) stands out for using a small amount of labeled points for data clustering and classification. In this scenario graph-based methods allow the analysis of local and global characteristics of the available data by identifying classes or groups regardless data distribution and representing submanifold in Euclidean space. Most of methods used in literature for SSL classification do not worry about graph construction. However, regular graphs can obtain better classification accuracy compared to traditional methods such as k-nearest neighbor (kNN), since kNN benefits the generation of hubs and it is not appropriate for high-dimensionality data. Nevertheless, methods commonly used for generating regular graphs have high computational cost. We tackle this problem introducing an alternative method for generation of regular graphs with better runtime performance compared to methods usually find in the area. Our technique is based on the preferential selection of vertices according some topological measures, like closeness, generating at the end of the process a regular graph. Experiments using the global and local consistency method for label propagation show that our method provides better or equal classification rate in comparison with kNN

Successive X-class Flares and Coronal Mass Ejections Driven by Shearing Motion and Sunspot Rotation in Active Region NOAA 12673

Science.gov (United States)

Yan, X. L.; Wang, J. C.; Pan, G. M.; Kong, D. F.; Xue, Z. K.; Yang, L. H.; Li, Q. L.; Feng, X. S.

2018-03-01

We present a clear case study on the occurrence of two successive X-class flares, including a decade-class flare (X9.3) and two coronal mass ejections (CMEs) triggered by shearing motion and sunspot rotation in active region NOAA 12673 on 2017 September 6. A shearing motion between the main sunspots with opposite polarities began on September 5 and lasted even after the second X-class flare on September 6. Moreover, the main sunspot with negative polarity rotated around its umbral center, and another main sunspot with positive polarity also exhibited a slow rotation. The sunspot with negative polarity at the northwest of the active region also began to rotate counterclockwise before the onset of the first X-class flare, which is related to the formation of the second S-shaped structure. The successive formation and eruption of two S-shaped structures were closely related to the counterclockwise rotation of the three sunspots. The existence of a flux rope is found prior to the onset of two flares by using nonlinear force-free field extrapolation based on the vector magnetograms observed by Solar Dynamics Observatory/Helioseismic and Magnetic Image. The first flux rope corresponds to the first S-shaped structures mentioned above. The second S-shaped structure was formed after the eruption of the first flux rope. These results suggest that a shearing motion and sunspot rotation play an important role in the buildup of the free energy and the formation of flux ropes in the corona that produces solar flares and CMEs.

On the correlation of longitudinal and latitudinal motions of sunspots

International Nuclear Information System (INIS)

Gilman, P.A.

1984-01-01

Using new measurements of positions of individual sunspots and sunspot groups obtained from 62 years of the Mt. Wilson white-light plate collection, we have recomputed the correlation between longitude and latitude motion. Our results for groups are similar to those of Ward (1965a) computed from the Greenwich record, but for individual spots the covariance is reduced by a factor of about 3 from the Ward values, though still of the same sign and still statistically significant. We conclude that there is a real correlation between longitude and latitude movement of individual spots, implying angular momentum transport toward the equator as inferred by Ward. The two thirds reduction in the covariance for individual spots as opposed to groups is probably due to certain properties of spot groups, as first pointed out in an unpublished manuscript by Leighton. (orig.)

A semi-empirical formula for total cross sections of electron scattering from diatomic molecules

International Nuclear Information System (INIS)

Liu Yufang; Sun Jinfeng; Henan Normal Univ., Xinxiang

1996-01-01

A fitting formula based on the Born approximation is used to fit the total cross sections for electron scattering by diatomic molecules (CO, N 2 , NO, O 2 and HCl) in the intermediate- and high-energy range. By analyzing the fitted parameters and the total cross sections, we found that the internuclear distance of the constituent atoms plays an important role in the e-diatomic molecule collision process. Thus a new semi-empirical formula has been obtained. There is no free parameter in the formula, and the dependence of the total cross sections on the internuclear distance has been reflected clearly. The total cross sections for electron scattering by CO, N 2 , NO, O 2 and HCl have been calculated over an incident energy range of 10-4000 eV. The results agree well with other available experimental and calculation data. (orig.)

Semi-Empirical Predictions on the Structure and Properties of ent-Kaurenoic Acid and Derivatives

Directory of Open Access Journals (Sweden)

Jose Isagani B. Janairo

2011-01-01

Full Text Available The physicochemical properties of ent- kaurenoic acid model derivatives, which possibly influence its therapeutic application, were calculated. Results revealed that the molecule possess favourable attributes which renders it possible to be considered as a drug lead only that its very hydrophobic nature can result to poor bioavailabilty, low absorption and poor systemic circulation. In silico simulations revealed that this setback can be overcome by introduction of hydroxyl group to the tertiary carbon of ent-kaurenoic acid employing m-CPBA catalyzed hydroxylation, thus, unleashing its full drug potency. Moreover, molecular similarity analyses derived from semi-empirical calculations between ent-kaurenoic acid and a set of kaurane diterpenoids showed differences in hydrophobic complementarity, size and electronic properties despite possessing nearly identical molecular frameworks, thus, arriving in a generalization for their observed mechanistic differences on acting on different targets.

The Determinants of House Prices and Construction: An Empirical Investigation of the Swiss Housing Economy

DEFF Research Database (Denmark)

Borowiecki, Karol

2009-01-01

This paper studies the Swiss housing price determinants. The Swiss housing economy is reproduced by employing a macro-series from the last seventeen years and constructing a vector-autoregressive model. Conditional on a comparatively broad set of fundamental determinants considered, i.e. wealth......, banking, demographic and real estate specific variables, the following findings are made: 1) real house price growth and construction activity dynamics are most sensitive to changes in population and construction prices, whereas real GDP, in contrary to common empirical findings in other countries, turns...

A simple semi-empirical way of accounting for the contribution of pair production process to the efficiency of Ge detectors

International Nuclear Information System (INIS)

Sudarshan, M.; Singh, R.

1991-01-01

By considering the data for a 38cm 3 Ge(Li) detector from E γ = 319.80 to 2598.80 keV, and for a 68 cm 3 HPGe detector from E γ = 223.430 to 3253.610 keV, it has been demonstrated that the contribution of the pair production process to the full energy peak efficiency (FEPE) of germanium detectors can be quite adequately accounted for in a semi-empirical way. (author)

The chromosphere above a δ-sunspot in the presence of fan-shaped jets

Science.gov (United States)

Robustini, Carolina; Leenaarts, Jorrit; de la Cruz Rodríguez, Jaime

2018-01-01

Context. Delta-sunspots are known to be favourable locations for fast and energetic events like flares and coronal mass ejections. The photosphere of this sunspot type has been thoroughly investigated in the past three decades. The atmospheric conditions in the chromosphere are not as well known, however. Aims: This study is focused on the chromosphere of a δ-sunspot that harbours a series of fan-shaped jets in its penumbra. The aim of this study is to establish the magnetic field topology and the temperature distribution in the presence of jets in the photosphere and the chromosphere. Methods: We use data from the Swedish 1m Solar Telescope (SST) and the Solar Dynamics Observatory. We invert the spectropolarimetric Fe I 6302 Å and Ca II 8542 Å data from the SST using the non-LTE inversion code NICOLE to estimate the magnetic field configuration, temperature, and velocity structure in the chromosphere. Results: A loop-like magnetic structure is observed to emerge in the penumbra of the sunspot. The jets are launched from this structure. Magnetic reconnection between this emerging field and the pre-existing vertical field is suggested by hot plasma patches on the interface between the two fields. The height at which the reconnection takes place is located between log τ500 = -2 and log τ500 = -3. The magnetic field vector and the atmospheric temperature maps show a stationary configuration during the whole observation. Movies associated to Figs. 3-5 are available at http://www.aanda.org

On the evolution of magnetic and velocity fields of an originating sunspot group

International Nuclear Information System (INIS)

Bachmann, G.

1978-01-01

Magnetographic measurements were made to derive longitudinal magnetic field strengths, line-of-sight velocities and the brightness distribution in an originating sunspot group. These results and photographs of the group are used to compare the evaluation of a relatively simple active region with our present ideas about the evolution of active regions in general. We found that the total magnetic flux increased from about 4 to 20x10 20 Mx over three days. The downward flow of gas in regions with stronger magnetic fields is formed only after the magnetic field has already been bipolar for two days. The maximum velocity always occurred in the main spots of the preceding and the subsequent parts of the sunspot group. Transformation into a flow pattern, which looks like Evershed motion, is observed in the main preceding sunspot after the formation of the penumbra. The generation of new active regions by concentration and amplification of magnetic fields, under the action of supergranulation flow in photospheric layers, cannot play an important role. On the contrary, the behaviour of the active region is in agreement with the conception of rising flux tubes, out of which the gas flows down. Our observations confirm that a magnetic field strength, leading to the generation of sunspots, is attained earlier in the preceding part of the originating active region than in its subsequent part. A series of subflares occurred in the active region, when short-lived small magnetic structure elements emerged in the larger bipolar magnetic field. (author)

Essential features of long-term changes of areas and diameters of sunspot groups in solar activity cycles 12-24

Science.gov (United States)

Efimenko, V. M.; Lozitsky, V. G.

2018-06-01

We analyze the Greenwich catalog data on areas of sunspot groups of last thirteen solar cycles. Various parameters of sunspots are considered, namely: average monthly smoothed areas, maximum area for each year and equivalent diameters of groups of sunspots. The first parameter shows an exceptional power of the 19th cycle of solar activity, which appears here more contrastively than in the numbers of spots (that is, in Wolf's numbers). It was found that in the maximum areas of sunspot groups for a year there is a unique phenomenon: a short and high jump in the 18th cycle (in 1946-1947) that has no analogues in other cycles. We also studied the integral distributions for equivalent diameters and found the following: (a) the average value of the index of power-law approximation is 5.4 for the last 13 cycles and (b) there is reliable evidence of Hale's double cycle (about 44 years). Since this indicator reflects the dispersion of sunspot group diameters, the results obtained show that the convective zone of the Sun generates embryos of active regions in different statistical regimes which change with a cycle of about 44 years.

Effect of solar flare ans sunspot numbers on the intensity of 5577A line in the night airglow

International Nuclear Information System (INIS)

Kundu, N.; Ghosh, S.N.

1981-01-01

The effects of solar flare and sunspot number on the intensity of 5577 A line emission are presented. The time lag between the occurrence of a flare and the enhancement of 5577 A line intensity is determined by observing the intensity of the line on three successive nights- the night preceding the flare and the two nights following it. The velocity of the solar corpuscles is then calculated. The value obtained at Allahabad (2400 Km/sec) is in agreement with the De Jager's prediction for explosive flare. Day-to-day analyses of the observations taken at Allahabad exhibit high correlation of the intensity of 5577 A line emission with sunspot number. Also, correlation is found for the intensity of 5577 A with the change in sunspot number (DELTA R) from the day preceding the night of observation to the day following it. The intensity appears to vary with the magnetic field produced by the sunspot and not with the spot area. (author)

SemiBoost: boosting for semi-supervised learning.

Science.gov (United States)

Mallapragada, Pavan Kumar; Jin, Rong; Jain, Anil K; Liu, Yi

2009-11-01

Semi-supervised learning has attracted a significant amount of attention in pattern recognition and machine learning. Most previous studies have focused on designing special algorithms to effectively exploit the unlabeled data in conjunction with labeled data. Our goal is to improve the classification accuracy of any given supervised learning algorithm by using the available unlabeled examples. We call this as the Semi-supervised improvement problem, to distinguish the proposed approach from the existing approaches. We design a metasemi-supervised learning algorithm that wraps around the underlying supervised algorithm and improves its performance using unlabeled data. This problem is particularly important when we need to train a supervised learning algorithm with a limited number of labeled examples and a multitude of unlabeled examples. We present a boosting framework for semi-supervised learning, termed as SemiBoost. The key advantages of the proposed semi-supervised learning approach are: 1) performance improvement of any supervised learning algorithm with a multitude of unlabeled data, 2) efficient computation by the iterative boosting algorithm, and 3) exploiting both manifold and cluster assumption in training classification models. An empirical study on 16 different data sets and text categorization demonstrates that the proposed framework improves the performance of several commonly used supervised learning algorithms, given a large number of unlabeled examples. We also show that the performance of the proposed algorithm, SemiBoost, is comparable to the state-of-the-art semi-supervised learning algorithms.

Distribution of electric currents in sunspots from photosphere to corona

Energy Technology Data Exchange (ETDEWEB)

Gosain, Sanjay [National Solar Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Démoulin, Pascal [Observatoire de Paris, LESIA, UMR 8109 (CNRS), F-92195 Meudon Principal Cedex (France); López Fuentes, Marcelo [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC. 67, Suc. 28 Buenos Aires 1428 (Argentina)

2014-09-20

We present a study of two regular sunspots that exhibit nearly uniform twist from the photosphere to the corona. We derive the twist parameter in the corona and in the chromosphere by minimizing the difference between the extrapolated linear force-free field model field lines and the observed intensity structures in the extreme-ultraviolet images of the Sun. The chromospheric structures appear more twisted than the coronal structures by a factor of two. Further, we derive the vertical component of electric current density, j{sub z} , using vector magnetograms from the Hinode Solar Optical Telescope (SOT). The spatial distribution of j{sub z} has a zebra pattern of strong positive and negative values owing to the penumbral fibril structure resolved by Hinode/SOT. This zebra pattern is due to the derivative of the horizontal magnetic field across the thin fibrils; therefore, it is strong and masks weaker currents that might be present, for example, as a result of the twist of the sunspot. We decompose j{sub z} into the contribution due to the derivatives along and across the direction of the horizontal field, which follows the fibril orientation closely. The map of the tangential component has more distributed currents that are coherent with the chromospheric and coronal twisted structures. Moreover, it allows us to map and identify the direct and return currents in the sunspots. Finally, this decomposition of j{sub z} is general and can be applied to any vector magnetogram in order to better identify the weaker large-scale currents that are associated with coronal twisted/sheared structures.

High Velocity Horizontal Motions at the Edge of Sunspot Penumbrae

Science.gov (United States)

Hagenaar-Daggett, Hermance J.; Shine, R.

2010-05-01

The outer edges of sunspot penumbrae have long been noted as a region of interesting dynamics including formation of MMFs, extensions and retractions of the penumbral tips, fast moving (2-3 km/s) bright features dubbed"streakers", and localized regions of high speed downflows interpreted as Evershed "sinks". Using 30s cadence movies of high spatial resolution G band and Ca II H images taken by the Hinode SOT/FPP instrument from 5-7 Jan 2007, we have been investigating the penumbra around a sunspot in AR 10933. In addition to the expected phenomena, we also see occasional small dark crescent-shaped features with high horizontal velocities (6.5 km/s) in G band movies. These appear to be emitted from penumbral tips. They travel about 1.5 Mm developing a bright wake that evolves into a slower moving (1-2 km/s) bright feature. In some cases, there may be an earlier outward propagating disturbance within the penumbra. We have also analyzed available Fe 6302 Stokes V images to obtain information on the magnetic field. Although only lower resolution 6302 images made with a slower cadence are available for these particular data sets, we can establish that the features have the opposite magnetic polarity of the sunspot. This observation may be in agreement with simulations showing that a horizontal flux tube develops crests that move outward with a velocity as large as 10 km/s. This work was supported by NASA contract NNM07AA01C.

Deciphering solar magnetic activity. I. On the relationship between the sunspot cycle and the evolution of small magnetic features

Energy Technology Data Exchange (ETDEWEB)

McIntosh, Scott W.; Wang, Xin; Markel, Robert S.; Thompson, Michael J. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Leamon, Robert J.; Malanushenko, Anna V. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Davey, Alisdair R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Howe, Rachel [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Krista, Larisza D. [Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80205 (United States); Cirtain, Jonathan W. [Marshall Space Flight Center, Code ZP13, Huntsville, AL 35812 (United States); Gurman, Joseph B.; Pesnell, William D., E-mail: mscott@ucar.edu [Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2014-09-01

Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ∼22 yr. The principal variation of sunspots, an ∼11 yr variation, modulates the amount of the magnetic field that pierces the solar surface and drives significant variations in our star's radiative, particulate, and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11 yr sunspot variation is intrinsically tied to the spatio-temporal overlap of the activity bands belonging to the 22 yr magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer-scale variability.

INTERFERENCE OF THE RUNNING WAVES AT LIGHT BRIDGES OF A SUNSPOT

Energy Technology Data Exchange (ETDEWEB)

Su, J. T.; Priya, T. G.; Yu, S. J.; Zhang, M. [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Ji, K. F. [Kunming University of Science and Technology, Kunming 650093 (China); Banerjee, D. [Indian Institute of Astrophysics, Koramangala Bangalore 560034 (India); Cao, W. D. [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States); Zhao, J. S.; Ji, H. S., E-mail: jt@bao.ac.cn [Purple Mountain Observatory, CAS, Nanjing 210008 (China)

2016-01-01

The observations of chromospheric oscillations of two umbral light bridges (LBs) within a sunspot from NOAA Active Region 12127 are presented. It was found that the running umbral waves with periods of 2.2–2.6 minutes underwent very fast damping before approaching umbral boundaries, while those with higher periods (>2.6 minutes) could propagate outside umbrae. On two sides of each LB adjacent to umbrae, the cross-wavelet spectra displayed that the oscillations on them had a common significant power region with dominant frequencies of 2–6 minutes and phase differences of ∼90°. A counterstream of two running umbral waves in the 2–6 minute frequency range propagated toward the LBs, where they encountered each other and gave rise to constructive or even destructive interference on the LBs. In addition, the velocity and density perturbations on the LBs were found in opposite phases suggesting that the perturbations were caused by the downward propagating waves.

SUNSPOT AND STARSPOT LIFETIMES IN A TURBULENT EROSION MODEL

Energy Technology Data Exchange (ETDEWEB)

Litvinenko, Yuri E. [Department of Mathematics, University of Waikato, P. B. 3105, Hamilton (New Zealand); Wheatland, M. S. [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

2017-01-10

Quantitative models of sunspot and starspot decay predict the timescale of magnetic diffusion and may yield important constraints in stellar dynamo models. Motivated by recent measurements of starspot lifetimes, we investigate the disintegration of a magnetic flux tube by nonlinear diffusion. Previous theoretical studies are extended by considering two physically motivated functional forms for the nonlinear diffusion coefficient D : an inverse power-law dependence D ∝ B {sup −ν} and a step-function dependence of D on the magnetic field magnitude B . Analytical self-similar solutions are presented for the power-law case, including solutions exhibiting “super fast” diffusion. For the step-function case, the heat-balance integral method yields approximate solutions, valid for moderately suppressed diffusion in the spot. The accuracy of the resulting solutions is confirmed numerically, using a method which provides an accurate description of long-time evolution by imposing boundary conditions at infinite distance from the spot. The new models may allow insight into the differences and similarities between sunspots and starspots.

Semi-empirical modelling of radiation exposure of humans to naturally occurring radioactive materials in a goldmine in Ghana

International Nuclear Information System (INIS)

Darko, E. O.; Tetteh, G.K.; Akaho, E.H.K.

2005-01-01

A semi-empirical analytical model has been developed and used to assess the radiation doses to workers in a gold mine in Ghana. The gamma dose rates from naturally occurring radioactive materials (uranium-thorium series, potassium-40 and radon concentrations) were related to the annual effective doses for surface and underground mining operations. The calculated effective doses were verified by comparison with field measurements and correlation ratios of 0.94 and 0.93 were obtained, respectively, between calculated and measured data of surface and underground mining. The results agreed with the approved international levels for normal radiation exposure in the mining environment. (au)

Possibility to explain the temperature distribution in sunspots by an anisotropic heat transfer

Energy Technology Data Exchange (ETDEWEB)

Eschrich, K O; Krause, F [Akademie der Wissenschaften der DDR, Potsdam. Zentralinstitut fuer Astrophysik

1977-01-01

Numerical solutions of a heat conduction problem in an anisotropic medium are used for a discussion of the possibility to explain the temperature distribution in sunspots and their environment. The anisotropy is assumed being due to the strong magnetic field in sunspots and the region below. This magnetic field forces the convection to take an anisotropic structure (two-dimensional turbulence) and thus the region gets anisotropic conduction properties, on the average. The discussion shows that the observed temperature profiles can be explained in the case the depth of the region of anisotropy is about as large as the diameter of the spot or larger.

MEASUREMENTS OF ABSORPTION, EMISSIVITY REDUCTION, AND LOCAL SUPPRESSION OF SOLAR ACOUSTIC WAVES IN SUNSPOTS

International Nuclear Information System (INIS)

Chou, D.-Y.; Liang, Z.-C.; Yang, M.-H.; Zhao Hui; Sun, M.-T.

2009-01-01

The power of solar acoustic waves in magnetic regions is lower relative to the quiet Sun. Absorption, emissivity reduction, and local suppression of acoustic waves contribute to the observed power reduction in magnetic regions. We propose a model for the energy budget of acoustic waves propagating through a sunspot in terms of the coefficients of absorption, emissivity reduction, and local suppression of the sunspot. Using the property that the waves emitted along the wave path between two points have no correlation with the signal at the starting point, we can separate the effects of these three mechanisms. Applying this method to helioseismic data filtered with direction and phase-velocity filters, we measure the fraction of the contribution of each mechanism to the power deficit in the umbra of the leading sunspot of NOAA 9057. The contribution from absorption is 23.3 ± 1.3%, emissivity reduction 8.2 ± 1.4%, and local suppression 68.5 ± 1.5%, for a wave packet corresponding to a phase velocity of 6.98 x 10 -5 rad s -1 .

Automated Sunspot Detection and Classification Using SOHO/MDI Imagery

Science.gov (United States)

2015-03-01

to the geocentric North). 3. Focus and size of the solar disk is adjusted to fit an 18 cm diameter circle on the worksheet. 4. Analyst hand draws the...General Nature of the Sunspot,” The Astrophysical Journal 230, 905–913 (1979). 14. Wheatland, M. S., “A Bayesian Approach to Solar Flare Prediction,” The

Empirical research on the influencing factors of the occupational stress for construction workers

Science.gov (United States)

LV, Xing; WU, Xiang; CI, Huipeng; LIU, Qing; YAO, Yongzheng

2017-04-01

Employee’s occupational stress and safety performance are highly related, which has been generally recognized by the researchers. We did this research to understand the status of the stress for construction workers, and explore the influence factors of pressure source with characteristics of construction industry. Based on the results of previous studies, we designed questionnaire to collect the influence factors on occupational stressors. The study selected workers from certain construction units at the grass-roots level as sample source. According to the results of the questionnaire, we redesigned the interview outline, and did the semi-structured interviews on workers randomly selected. Finally, we developed a scale which combined the characteristics of construction projects in China. Using SPSS software for factor analysis, reliability analysis, and descriptive statistical analysis, the results show that there are six factors affecting the workers’ occupational stress, including The Work Itself, Family-Work, Career Development, Organization Style, Interpersonal Relationship and Role Management Style. The work itself is the main sources of occupational stress. The results can be used by the construction company to provide guidance for workers to control and manage occupational stress.

3-color photometry of a sunspot using speckle masking techniques

NARCIS (Netherlands)

Wiehr, E.; Sütterlin, P.

1998-01-01

A three-colour photometry is used to deduce the temperature of sunspot fine-structures. Using the Speckle-Masking method for image restoration, the resulting images (one per colour and burst) have a spatial resolution only limited by the telescope's aperture, i.e. 95km (blue), 145 km (red) and

A control-oriented real-time semi-empirical model for the prediction of NOx emissions in diesel engines

International Nuclear Information System (INIS)

D’Ambrosio, Stefano; Finesso, Roberto; Fu, Lezhong; Mittica, Antonio; Spessa, Ezio

2014-01-01

Highlights: • New semi-empirical correlation to predict NOx emissions in diesel engines. • Based on a real-time three-zone diagnostic combustion model. • The model is of fast application, and is therefore suitable for control-oriented applications. - Abstract: The present work describes the development of a fast control-oriented semi-empirical model that is capable of predicting NOx emissions in diesel engines under steady state and transient conditions. The model takes into account the maximum in-cylinder burned gas temperature of the main injection, the ambient gas-to-fuel ratio, the mass of injected fuel, the engine speed and the injection pressure. The evaluation of the temperature of the burned gas is based on a three-zone real-time diagnostic thermodynamic model that has recently been developed by the authors. Two correlations have also been developed in the present study, in order to evaluate the maximum burned gas temperature during the main combustion phase (derived from the three-zone diagnostic model) on the basis of significant engine parameters. The model has been tuned and applied to two diesel engines that feature different injection systems of the indirect acting piezoelectric, direct acting piezoelectric and solenoid type, respectively, over a wide range of steady-state operating conditions. The model has also been validated in transient operation conditions, over the urban and extra-urban phases of an NEDC. It has been shown that the proposed approach is capable of improving the predictive capability of NOx emissions, compared to previous approaches, and is characterized by a very low computational effort, as it is based on a single-equation correlation. It is therefore suitable for real-time applications, and could also be integrated in the engine control unit for closed-loop or feed-forward control tasks

Depressed emission between magnetic arcades near a sunspot

Science.gov (United States)

Ryabov, B. I.; Shibasaki, K.

The locations of the depressed emission in microwaves, EUV and soft X-rays are compared with each other and with the location of the plasma outflow in the active region (AR) 8535 on the Sun. We found that two open-field regions overlap the regions of depressed emission near the AR's sunspot. These two open-field regions are simulated with the potential-field source-surface (PFSS) model under radial distances of RSS = 1.8 R⊙ and RSS = 2.5 R⊙. Each open-field region is located between the arcades of the loops of the same magnetic polarity. The former open-field region covers the region of the plasma outflow, which is thus useful for the tests on connection to the heliosphere. The utmost microwave depression of the intensity in the ordinary mode (the Very Large Array 15 GHz observations) also overlaps the region of the plasma outflow and thus indicates this outflow. The lasting for eight days depression in soft X-rays and the SOHO EIT 2.84× 10-8 m images are attributed to the evacuation of as hot coronal plasma as T≥ 2× 106 K from the extended in height (``open") magnetic structures. We conclude that the AR 8535 presents the sunspot atmosphere affected by the large-scale magnetic fields.

ASYMMETRIC SUNSPOT ACTIVITY AND THE SOUTHWARD DISPLACEMENT OF THE HELIOSPHERIC CURRENT SHEET

International Nuclear Information System (INIS)

Wang, Y.-M.; Robbrecht, E.

2011-01-01

Observations of the interplanetary magnetic field (IMF) have suggested a statistical tendency for the heliospheric current sheet (HCS) to be shifted a few degrees southward of the heliographic equator during the period 1965-2010, particularly in the years near sunspot minimum. Using potential-field source-surface extrapolations and photospheric flux-transport simulations, we demonstrate that this southward displacement follows from Joy's law and the observed hemispheric asymmetry in the sunspot numbers, with activity being stronger in the southern (northern) hemisphere during the declining (rising) phase of cycles 20-23. The hemispheric asymmetry gives rise to an axisymmetric quadrupole field, whose equatorial zone has the sign of the leading-polarity flux in the dominant hemisphere; during the last four cycles, the polarity of the IMF around the equator thus tended to match that of the north polar field both before and after polar field reversal. However, large fluctuations are introduced by the nonaxisymmetric field components, which depend on the longitudinal distribution of sunspot activity in either hemisphere. Consistent with this model, the HCS showed an average northward displacement during cycle 19, when the 'usual' alternation was reversed and the northern hemisphere became far more active than the southern hemisphere during the declining phase of the cycle. We propose a new method for determining the north-south displacement of the HCS from coronal streamer observations.

Semi-annual Sq-variation in solar activity cycle

Science.gov (United States)

Pogrebnoy, V.; Malosiev, T.

The peculiarities of semi-annual variation in solar activity cycle have been studied. The data from observatories having long observational series and located in different latitude zones were used. The following observatories were selected: Huancayo (magnetic equator), from 1922 to 1959; Apia (low latitudes), from 1912 to 1961; Moscow (middle latitudes), from 1947 to 1965. Based on the hourly values of H-components, the average monthly diurnal amplitudes (a difference between midday and midnight values), according to five international quiet days, were computed. Obtained results were compared with R (relative sunspot numbers) in the ranges of 0-30R, 40-100R, and 140-190R. It was shown, that the amplitude of semi-annual variation increases with R, from minimum to maximum values, on average by 45%. At equatorial Huancayo observatory, the semi-annual Sq(H)-variation appears especially clearly: its maximums take place at periods of equinoxes (March-April, September-October), and minimums -- at periods of solstices (June-July, December-January). At low (Apia observatory) and middle (Moscow observatory) latitudes, the character of semi-annual variation is somewhat different: it appears during the periods of equinoxes, but considerably less than at equator. Besides, with the growth of R, semi-annual variation appears against a background of annual variation, in the form of second peaks (maximum in June). At observatories located in low and middle latitudes, second peaks become more appreciable with an increase of R (March-April and September-October). During the periods of low solar activity, they are insignificant. This work has been carried out with the support from International Scientific and Technology Center (Project #KR-214).

Kinetic and empirical design criteria for constructed wetlands

International Nuclear Information System (INIS)

Nix, P.G.; Gulley, J.R.

1995-01-01

A study was conducted to demonstrate the capabilities of wetlands as long-term, self-sustaining natural systems for the treatment of large quantities of waste water released from tailings ponds after mine abandonment. Constructed wetlands were built and planted with aquatic plants. The experimental design included three replicate trenches for each of two treatment systems. The objective of the research was to assess the optimum contaminant loading rates which would result in an acceptable quality of the effluent water. Using empirical data (i.e., hydrocarbon loading rates versus effluent quality), the optimal range of hydrocarbon loading was 5 to 25 gTEH/m 2/ month. Using more conservative kinetic data (i.e. microbial mineralization rates), the range of optimal treatment effectiveness was 9.6 to 13.2 gTEH/m 2/ month. The two design criteria methodologies were calculated using two independent analytical methods. The similarity in results was judged to be a confirmation of their accuracy. 20 refs., 5 figs

A simple semi-empirical technique for apportioning the impact of roadways on air quality in an urban neighbourhood

Science.gov (United States)

Elangasinghe, M. A.; Dirks, K. N.; Singhal, N.; Costello, S. B.; Longley, I.; Salmond, J. A.

2014-02-01

Air pollution from the transport sector has a marked effect on human health, so isolating the pollutant contribution from a roadway is important in understanding its impact on the local neighbourhood. This paper proposes a novel technique based on a semi-empirical air pollution model to quantify the impact from a roadway on the air quality of a local neighbourhood using ambient records of a single air pollution monitor. We demonstrate the proposed technique using a case study, in which we quantify the contribution from a major highway with respect to the local background concentration in Auckland, New Zealand. Comparing the diurnal variation of the model-separated background contribution with real measurements from a site upwind of the highway shows that the model estimates are reliable. Amongst all of the pollutants considered, the best estimations of the background were achieved for nitrogen oxides. Although the multi-pronged approach worked well for predominantly vehicle-related pollutants, it could not be used effectively to isolate emissions of PM10 due to the complex and less predictable influence of natural sources (such as marine aerosols). The proposed approach is useful in situations where ambient records from an upwind background station are not available (as required by other techniques) and is potentially transferable to situations such as intersections and arterial roads. Applying this technique to longer time series could help to understand the changes in pollutant concentrations from the road and background sources for different emission scenarios, for different years or seasons. Modelling results also show the potential of such a hybrid semi-empirical models to contribute to our understanding of the physical parameters determining air quality and to validate emissions inventory data.

Predicting Maximum Sunspot Number in Solar Cycle 24 Nipa J Bhatt ...

Indian Academy of Sciences (India)

Key words. Sunspot number—precursor prediction technique—geo- magnetic activity index aa. 1. Introduction. Predictions of solar and geomagnetic activities are important for various purposes, including the operation of low-earth orbiting satellites, operation of power grids on. Earth, and satellite communication systems.

Evaluation by fluorescence, STD-NMR, docking and semi-empirical calculations of the o-NBA photo-acid interaction with BSA

Science.gov (United States)

Chaves, Otávio A.; Jesus, Catarina S. H.; Cruz, Pedro F.; Sant'Anna, Carlos M. R.; Brito, Rui M. M.; Serpa, Carlos

2016-12-01

Serum albumins present reversible pH dependent conformational transitions. A sudden laser induced pH-jump is a methodology that can provide new insights on localized protein (un)folding processes that occur within the nanosecond to microsecond time scale. To generate the fast pH jump needed to fast-trigger a protein conformational event, a photo-triggered acid generator as o-nitrobenzaldehyde (o-NBA) can be conveniently used. In order to detect potential specific or nonspecific interactions between o-NBA and BSA, we have performed ligand-binding studies using fluorescence spectroscopy, saturation transfer difference (STD) NMR, molecular docking and semi-empirical calculations. Fluorescence quenching indicates the formation of a non-fluorescent complex in the ground-state between the fluorophore and the quencher, but o-NBA does not bind much effectively to the protein (Ka 4.34 × 103 M- 1) and thus can be considered a relatively weak binder. The corresponding thermodynamic parameters: ΔG°, ΔS° and ΔH° showed that the binding process is spontaneous and entropy driven. Results of 1H STD-NMR confirm that the photo-acid and BSA interact, and the relative intensities of the signals in the STD spectra show that all o-NBA protons are equally involved in the binding process, which should correspond to a nonspecific interaction. Molecular docking and semi-empirical calculations suggest that the o-NBA binds preferentially to the Trp-212-containing site of BSA (FA7), interacting via hydrogen bonds with Arg-217 and Tyr-149 residues.

THE FORMATION OF AN INVERSE S-SHAPED ACTIVE-REGION FILAMENT DRIVEN BY SUNSPOT MOTION AND MAGNETIC RECONNECTION

Energy Technology Data Exchange (ETDEWEB)

Yan, X. L.; Xue, Z. K.; Wang, J. C.; Yang, L. H. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Priest, E. R. [Mathematics Institute, University of St Andrews, St Andrews, KY16 9SS (United Kingdom); Guo, Q. L., E-mail: yanxl@ynao.ac.cn [College of Mathematics Physics and Information Engineering, Jiaxing University, Jiaxing 314001 (China)

2016-11-20

We present a detailed study of the formation of an inverse S-shaped filament prior to its eruption in active region NOAA 11884 from 2013 October 31 to November 2. In the initial stage, clockwise rotation of a small positive sunspot around the main negative trailing sunspot formed a curved filament. Then the small sunspot cancelled with the negative magnetic flux to create a longer active-region filament with an inverse S-shape. At the cancellation site a brightening was observed in UV and EUV images and bright material was transferred to the filament. Later the filament erupted after cancellation of two opposite polarities below the upper part of the filament. Nonlinear force-free field extrapolation of vector photospheric fields suggests that the filament may have a twisted structure, but this cannot be confirmed from the current observations.

Semi-Markov processes

CERN Document Server

Grabski

2014-01-01

Semi-Markov Processes: Applications in System Reliability and Maintenance is a modern view of discrete state space and continuous time semi-Markov processes and their applications in reliability and maintenance. The book explains how to construct semi-Markov models and discusses the different reliability parameters and characteristics that can be obtained from those models. The book is a useful resource for mathematicians, engineering practitioners, and PhD and MSc students who want to understand the basic concepts and results of semi-Markov process theory. Clearly defines the properties and

Semi-empirical model for the threshold voltage of a double implanted MOSFET and its temperature dependence

Energy Technology Data Exchange (ETDEWEB)

Arora, N D

1987-05-01

A simple and accurate semi-empirical model for the threshold voltage of a small geometry double implanted enhancement type MOSFET, especially useful in a circuit simulation program like SPICE, has been developed. The effect of short channel length and narrow width on the threshold voltage has been taken into account through a geometrical approximation, which involves parameters whose values can be determined from the curve fitting experimental data. A model for the temperature dependence of the threshold voltage for the implanted devices has also been presented. The temperature coefficient of the threshold voltage was found to change with decreasing channel length and width. Experimental results from various device sizes, both short and narrow, show very good agreement with the model. The model has been implemented in SPICE as part of the complete dc model.

Questioning the Influence of Sunspots on Amazon Hydrology: Even a Broken Clock Tells the Right Time Twice a Day

Science.gov (United States)

Baker, J. C. A.; Gloor, M.; Boom, A.; Neill, D. A.; Cintra, B. B. L.; Clerici, S. J.; Brienen, R. J. W.

2018-02-01

It was suggested in a recent article that sunspots drive decadal variation in Amazon River flow. This conclusion was based on a novel time series decomposition method used to extract a decadal signal from the Amazon River record. We have extended this analysis back in time, using a new hydrological proxy record of tree ring oxygen isotopes (δ18OTR). Consistent with the findings of Antico and Torres, we find a positive correlation between sunspots and the decadal δ18OTR cycle from 1903 to 2012 (r = 0.60, p r = -0.30, p = 0.11, 1799-1902). This result casts considerable doubt over the mechanism by which sunspots are purported to influence Amazon hydrology.

Semi-empirical Algorithm for the Retrieval of Ecology-Relevant Water Constituents in Various Aquatic Environments

Directory of Open Access Journals (Sweden)

Robert Shuchman

2009-03-01

Full Text Available An advanced operational semi-empirical algorithm for processing satellite remote sensing data in the visible region is described. Based on the Levenberg-Marquardt multivariate optimization procedure, the algorithm is developed for retrieving major water colour producing agents: chlorophyll-a, suspended minerals and dissolved organics. Two assurance units incorporated by the algorithm are intended to flag pixels with inaccurate atmospheric correction and specific hydro-optical properties not covered by the applied hydro-optical model. The hydro-optical model is a set of spectral cross-sections of absorption and backscattering of the colour producing agents. The combination of the optimization procedure and a replaceable hydro-optical model makes the developed algorithm not specific to a particular satellite sensor or a water body. The algorithm performance efficiency is amply illustrated for SeaWiFS, MODIS and MERIS images over a variety of water bodies.

Analyzing Mathematics Textbooks through a Constructive-Empirical Perspective on Abstraction: The Case of Pythagoras' Theorem

Science.gov (United States)

Yang, Kai-Lin

2016-01-01

This study aims at analyzing how Pythagoras' theorem is handled in three versions of Taiwanese textbooks using a conceptual framework of a constructive-empirical perspective on abstraction, which comprises three key attributes: the generality of the object, the connectivity of the subject and the functionality of diagrams as the focused semiotic…

Extreme Value Theory Applied to the Millennial Sunspot Number Series

Science.gov (United States)

Acero, F. J.; Gallego, M. C.; García, J. A.; Usoskin, I. G.; Vaquero, J. M.

2018-01-01

In this work, we use two decadal sunspot number series reconstructed from cosmogenic radionuclide data (14C in tree trunks, SN 14C, and 10Be in polar ice, SN 10Be) and the extreme value theory to study variability of solar activity during the last nine millennia. The peaks-over-threshold technique was used to compute, in particular, the shape parameter of the generalized Pareto distribution for different thresholds. Its negative value implies an upper bound of the extreme SN 10Be and SN 14C timeseries. The return level for 1000 and 10,000 years were estimated leading to values lower than the maximum observed values, expected for the 1000 year, but not for the 10,000 year return levels, for both series. A comparison of these results with those obtained using the observed sunspot numbers from telescopic observations during the last four centuries suggests that the main characteristics of solar activity have already been recorded in the telescopic period (from 1610 to nowadays) which covers the full range of solar variability from a Grand minimum to a Grand maximum.

Worldwide variation in atmospheric noise intensities with sunspot number: an in-depth look at the 20 to 24 hour seasonal time block

International Nuclear Information System (INIS)

Joglekar, P.J.; Sathiamurthy, T.S.

1975-01-01

Comparisons of the variation of atmospheric radio noise intensities for 20 to 24 hr to sunspot numbers have been completed. Statistical dependence between the noise intensities and sunspot numbers was found for different seasons at a number of frequencies for many locations in the global network of ARN-2 noise recorders. The noise intensities generally tended to decrease with sunspot number in the range from 50 kHz to 5 MHz, which is presumed to be due to increases in residual ionospheric absorption during nighttime. At frequencies greater than 5 MHz, noise intensities increased with sunspot number in many cases, which would be expected from our present knowledge of ionospheric behavior in the HF range. By convention, CCIR treats year-to-year variation in the noise intensities as random and includes them in the prediction uncertainty sigma /sub Fam/ (for which one value is given at a frequency for a seasonal time block for all locations) in system performance evaluation. An error analysis on a global basis shows that a large portion of the year-to-year variability is due to sunspot variation. This suggests the possibility of improved noise estimates. (auth)

A model of a sunspot chromosphere based on OSO 8 observations

Science.gov (United States)

Lites, B. W.; Skumanich, A.

1982-01-01

OSO 8 spectrometer observations of the H I, Mg II, and Ca II resonance lines of a large quiet sunspot during November 16-17, 1975, along with a C IV line of that event obtained by a ground-based spectrometer, are analyzed together with near-simultaneous ground-based Stokes measurements to yield an umbral chromosphere and transition region model. Features of this model include a chromosphere that is effectively thin in the resonance lines of H I and Mg II, while being saturated in Ca II, and an upper chromospheric structure similar to that of quiet-sun models. The similarity of the upper chromosphere of the sunspot umbra to the quiet-sun chromosphere suggests that the intense magnetic field plays only a passive role in the chromospheric heating mechanism, and the observations cited indicate that solar-type stars with large areas of ordered magnetic flux would not necessarily exhibit extremely active chromosphere.

SMALL-SCALE AND GLOBAL DYNAMOS AND THE AREA AND FLUX DISTRIBUTIONS OF ACTIVE REGIONS, SUNSPOT GROUPS, AND SUNSPOTS: A MULTI-DATABASE STUDY

Energy Technology Data Exchange (ETDEWEB)

Muñoz-Jaramillo, Andrés; Windmueller, John C.; Amouzou, Ernest C.; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Senkpeil, Ryan R. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Tlatov, Andrey G. [Kislovodsk Mountain Astronomical Station of the Pulkovo Observatory, Kislovodsk 357700 (Russian Federation); Nagovitsyn, Yury A. [Pulkovo Astronomical Observatory, Russian Academy of Sciences, St. Petersburg 196140 (Russian Federation); Pevtsov, Alexei A. [National Solar Observatory, Sunspot, NM 88349 (United States); Chapman, Gary A.; Cookson, Angela M. [San Fernando Observatory, Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330 (United States); Yeates, Anthony R. [Department of Mathematical Sciences, Durham University, South Road, Durham DH1 3LE (United Kingdom); Watson, Fraser T. [National Solar Observatory, Tucson, AZ 85719 (United States); Balmaceda, Laura A. [Institute for Astronomical, Terrestrial and Space Sciences (ICATE-CONICET), San Juan (Argentina); DeLuca, Edward E. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Martens, Petrus C. H., E-mail: munoz@solar.physics.montana.edu [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States)

2015-02-10

In this work, we take advantage of 11 different sunspot group, sunspot, and active region databases to characterize the area and flux distributions of photospheric magnetic structures. We find that, when taken separately, different databases are better fitted by different distributions (as has been reported previously in the literature). However, we find that all our databases can be reconciled by the simple application of a proportionality constant, and that, in reality, different databases are sampling different parts of a composite distribution. This composite distribution is made up by linear combination of Weibull and log-normal distributions—where a pure Weibull (log-normal) characterizes the distribution of structures with fluxes below (above) 10{sup 21}Mx (10{sup 22}Mx). Additionally, we demonstrate that the Weibull distribution shows the expected linear behavior of a power-law distribution (when extended to smaller fluxes), making our results compatible with the results of Parnell et al. We propose that this is evidence of two separate mechanisms giving rise to visible structures on the photosphere: one directly connected to the global component of the dynamo (and the generation of bipolar active regions), and the other with the small-scale component of the dynamo (and the fragmentation of magnetic structures due to their interaction with turbulent convection)

SOHO sees right through the Sun, and finds sunspots on the far side

Science.gov (United States)

2000-03-01

The story is told today in the journal Science by Charles Lindsey of Tucson, Arizona, and Doug Braun of Boulder, Colorado. They realised that the analytical witchcraft called helioseismic holography might open a window right through the Sun. And the technique worked when they used it to decode waves seen on the visible surface by one of SOHO's instruments, the Michelson Doppler Imager, or MDI. "We've known for ten years that in theory we could make the Sun transparent all the way to the far side," said Charles Lindsey. "But we needed observations of exceptional quality. In the end we got them, from MDI on SOHO." For more than 100 years scientists have been aware that groups of dark sunspots on the Sun's visible face are often the scene of flares and other eruptions. Nowadays they watch the Sun more closely than ever, because modern systems are much more vulnerable to solar disturbances than old-style technology was. The experts can still be taken by surprise, because the Sun turns on its axis. A large group of previously hidden sunspots can suddenly swing into view on the eastern (left-hand) edge of the Sun. It may already be blazing away with menacing eruptions. With a far-side preview of sunspots, nasty shocks for the space weather forecasters may now be avoidable. Last year, French and Finnish scientists used SWAN, another instrument on SOHO, to detect activity on the far side. They saw an ultraviolet glow lighting up gas in the Solar System beyond the Sun, and moving across the sky like a lighthouse beam as the Sun rotated. The method used by Lindsey and Braun with MDI data is completely different, and it pinpoints the source of the activity on the far side. Solar seismology chalks up another success Detection of sound waves reverberating through the Sun opened its gassy interior for investigation, in much the same way as seismologists learned to explore the Earth's rocky interior with earthquake waves. Using special telescopes on the ground and in space

Semi-empirical simulation of thermoluminescent response under different filter geometries

International Nuclear Information System (INIS)

Shammas, Gabriel Issa Jabra

2006-01-01

Many thermoluminescent materials has been developed and used for photon personal dosimetry but no one has all desired characteristics alone. These characteristics include robustness, high sensitivity, energy photon independence, large range of photon energy detection, good reproducibility, small fading and simple glow curve with peaks above 150 deg C. Calcium Sulfate Dysprosium doped (CaSO 4 :Dy) phosphor Thermoluminescent Dosimeter (TLD) has been used by many laboratories, mainly in Brazil and India. Another interesting phosphor is Calcium Fluoride (CaF 2 ). These phosphor advantages begin to be more required and its disadvantages have became more apparent, in a global market more and more competitive. These phosphors are used in environmental and area monitoring, once they present more sensibility than other phosphors, like LiF:Mg. Theirs mainly disadvantage is a strong energetic dependence response, which must be corrected for theirs application in the field, where photon radiation is unknown a priori. An interesting way do make this correction in orthogonal incidence of the radiation on the phosphor is to interject a plane leaked filter between the beam and the phosphor. In order to reduce the energetic dependence on any incidence angle, reducing the field dose measurement uncertainty too, this work presents a simulation study on spherical filter geometries. It was simulated photon irradiations with Gamma rays of 60 Co and x-rays of 33; 48 and 118 keV, on many incidence angles from zero to ninety degrees. These semi-empirical computational simulations using finite differences in three dimensions were done in spherical coordinates. The results pointed out the best filter thicknesses and widths, in order to optimize the correction on energetic dependence. (author)

Sunspot Light Walls Suppressed by Nearby Brightenings

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuhong; Zhang, Jun; Hou, Yijun; Li, Xiaohong [CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Erdélyi, Robertus [Solar Physics and Space Plasma Research Centre, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Yan, Limei, E-mail: shuhongyang@nao.cas.cn [Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China)

2017-07-01

Light walls, as ensembles of oscillating bright structures rooted in sunspot light bridges, have not been well studied, although they are important for understanding sunspot properties. Using the Interface Region Imaging Spectrograph and Solar Dynamics Observatory observations, here we study the evolution of two oscillating light walls each within its own active region (AR). The emission of each light wall decays greatly after the appearance of adjacent brightenings. For the first light wall, rooted within AR 12565, the average height, amplitude, and oscillation period significantly decrease from 3.5 Mm, 1.7 Mm, and 8.5 minutes to 1.6 Mm, 0.4 Mm, and 3.0 minutes, respectively. For the second light wall, rooted within AR 12597, the mean height, amplitude, and oscillation period of the light wall decrease from 2.1 Mm, 0.5 Mm, and 3.0 minutes to 1.5 Mm, 0.2 Mm, and 2.1 minutes, respectively. Particularly, a part of the second light wall even becomes invisible after the influence of a nearby brightening. These results reveal that the light walls are suppressed by nearby brightenings. Considering the complex magnetic topology in light bridges, we conjecture that the fading of light walls may be caused by a drop in the magnetic pressure, where the flux is canceled by magnetic reconnection at the site of the nearby brightening. Another hypothesis is that the wall fading is due to the suppression of driver source ( p -mode oscillation), resulting from the nearby avalanche of downward particles along reconnected brightening loops.

LOOKING FOR GRANULATION AND PERIODICITY IMPRINTS IN THE SUNSPOT TIME SERIES

Energy Technology Data Exchange (ETDEWEB)

Lopes, Ilídio [Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Silva, Hugo G., E-mail: ilidio.lopes@tecnico.ulisboa.pt, E-mail: hgsilva@uevora.pt [Departamento de Física, ECT, Instituto de Ciências da Terra, Universidade de Évora, Rua Romão Ramalho 59, 7002-554 Évora (Portugal)

2015-05-10

The sunspot activity is the end result of the cyclic destruction and regeneration of magnetic fields by the dynamo action. We propose a new method to analyze the daily sunspot areas data recorded since 1874. By computing the power spectral density of daily data series using the Mexican hat wavelet, we found a power spectrum with a well-defined shape, characterized by three features. The first term is the 22 yr solar magnetic cycle, estimated in our work to be 18.43 yr. The second term is related to the daily volatility of sunspots. This term is most likely produced by the turbulent motions linked to the solar granulation. The last term corresponds to a periodic source associated with the solar magnetic activity, for which the maximum power spectral density occurs at 22.67 days. This value is part of the 22–27 day periodicity region that shows an above-average intensity in the power spectra. The origin of this 22.67 day periodic process is not clearly identified, and there is a possibility that it can be produced by convective flows inside the star. The study clearly shows a north–south asymmetry. The 18.43 yr periodical source is correlated between the two hemispheres, but the 22.67 day one is not correlated. It is shown that toward the large timescales an excess occurs in the northern hemisphere, especially near the previous two periodic sources. To further investigate the 22.67 day periodicity, we made a Lomb–Scargle spectral analysis. The study suggests that this periodicity is distinct from others found nearby.

Semi-empirical Calculation of Detection Efficiency for Voluminous Source Based on Effective Solid Angle Concept

Energy Technology Data Exchange (ETDEWEB)

Kang, M. Y.; Kim, J. H.; Choi, H. D.; Sun, G. M. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

To calculate the full energy (FE) absorption peak efficiency for arbitrary volume sample, we developed and verified the Effective Solid Angle (ESA) Code. The procedure for semi-empirical determination of the FE efficiency for the arbitrary volume sources and the calculation principles and processes about ESA code is referred to, and the code was validated with a HPGe detector (relative efficiency 32%, n-type) in previous studies. In this study, we use different type and efficiency of HPGe detectors, in order to verify the performance of the ESA code for the various detectors. We calculated the efficiency curve of voluminous source and compared with experimental data. We will carry out additional validation by measurement of various medium, volume and shape of CRM volume sources with detector of different efficiency and type. And we will reflect the effect of the dead layer of p-type HPGe detector and coincidence summing correction technique in near future.

Fine structure in sunspots. IV. Penumbral grains in speckle reconstucted images

Czech Academy of Sciences Publication Activity Database

Sobotka, Michal; Suetterlin, P.

2001-01-01

Roč. 380, č. 2 (2001), s. 714-718 ISSN 0004-6361 R&D Projects: GA AV ČR KSK2043105; GA AV ČR IAA3003903 Institutional research plan: CEZ:AV0Z1003909 Keywords : sun * sunspots Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.790, year: 2000

Are climatological correlations with the Hale double sunspot cycle meaningful

International Nuclear Information System (INIS)

Goldberg, R.A.; Herman, J.R.

1975-09-01

A sunspot cycle which may have been subject to a predicted phase reversal between 1800 and 1880 A.D. is discussed. Several climatological parameters normally correlated with this cycle are examined and do not exhibit a corresponding phase reversal during this period. It is proposed that this apparent discrepency can be resolved by suitable observations during the upcoming half decade

The Formation of a Sunspot Penumbra Sector in Active Region NOAA 12574

Science.gov (United States)

Li, Qiaoling; Yan, Xiaoli; Wang, Jincheng; Kong, DeFang; Xue, Zhike; Yang, Liheng; Cao, Wenda

2018-04-01

We present a particular case of the formation of a penumbra sector around a developing sunspot in the active region NOAA 12574 on 2016 August 11 by using the high-resolution data observed by the New Solar Telescope at the Big Bear Solar Observatory and the data acquired by the Helioseismic and Magnetic Imager and the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory satellite. Before the new penumbra sector formed, the developing sunspot already had two umbrae with some penumbral filaments. The penumbra sector gradually formed at the junction of two umbrae. We found that the formation of the penumbra sector can be divided into two stages. First, during the initial stage of penumbral formation, the region where the penumbra sector formed always appeared blueshifted in a Dopplergram. The area, mean transverse magnetic field strength, and total magnetic flux of the umbra and penumbra sector all increased with time. The initial penumbral formation was associated with magnetic emergence. Second, when the penumbra sector appeared, the magnetic flux and area of the penumbra sector increased after the umbra’s magnetic flux and area decreased. These results indicate that the umbra provided magnetic flux for penumbral development after the penumbra sector appeared. We also found that the newly formed penumbra sector was associated with sunspot rotation. Based on these findings, we suggest that the penumbra sector was the result of the emerging flux that was trapped in the photosphere at the initial stage of penumbral formation, and when the rudimentary penumbra formed, the penumbra sector developed at the cost of the umbra.

Temperature mapping of sunspots and pores from speckle reconstructed three colour photometry

NARCIS (Netherlands)

Sütterlin, P.; Wiehr, E.

1998-01-01

The two-dimensional temperature distribution in a highly structured sunspot and in two small umbrae is determined from a three-colour photometry in narrow spectral continua. Disturbing influences from the earth’s atmosphere are removed by speckle masking techniques, yielding a spatial resolution

Relation of flare activity to the approach and separation of sunspots in an active region and to its magnetic properties

International Nuclear Information System (INIS)

Markova, E.

1978-01-01

The relation between the flare activity of active regions within the scope of a large complex and the magnetic gradients of these active regions and their daily variations is investigated in the interval of the exceptionally high flare activity occurring in June 1970. New indices, characterizing the active region, were defined, e.g., the instantaneous sunspot-area density and the instantaneous sunspot-number density. These indices were determined on the basis of measurements of the surface containing all sunspots of the complex of active regions enclosed by an envelope. An attempt was made to substitute the surface in the relation for the individual indices by distance. The daily variations of these indices were again compared with the flare activity and some mutual relations were derived. (author)

SOLAR CYCLE 24: CURIOUS CHANGES IN THE RELATIVE NUMBERS OF SUNSPOT GROUP TYPES

International Nuclear Information System (INIS)

Kilcik, A.; Yurchyshyn, V. B.; Ozguc, A.; Rozelot, J. P.

2014-01-01

Here, we analyze different sunspot group (SG) behaviors from the points of view of both the sunspot counts (SSCs) and the number of SGs, in four categories, for the time period of 1982 January-2014 May. These categories include data from simple (A and B), medium (C), large (D, E, and F), and decaying (H) SGs. We investigate temporal variations of all data sets used in this study and find the following results. (1) There is a very significant decrease in the large groups' SSCs and the number of SGs in solar cycle 24 (cycle 24) compared to cycles 21-23. (2) There is no strong variation in the decaying groups' data sets for the entire investigated time interval. (3) Medium group data show a gradual decrease for the last three cycles. (4) A significant decrease occurred in the small groups during solar cycle 23, while no strong changes show in the current cycle (cycle 24) compared to the previous ones. We confirm that the temporal behavior of all categories is quite different from cycle to cycle and it is especially flagrant in solar cycle 24. Thus, we argue that the reduced absolute number of the large SGs is largely, if not solely, responsible for the weak cycle 24. These results might be important for long-term space weather predictions to understand the rate of formation of different groups of sunspots during a solar cycle and the possible consequences for the long-term geomagnetic activity

The Temperature - Magnetic Field Relation in Observed and Simulated Sunspots

Czech Academy of Sciences Publication Activity Database

Sobotka, Michal; Rezaei, R.

2017-01-01

Roč. 292, č. 12 (2017), 188/1-188/12 ISSN 0038-0938 R&D Projects: GA ČR(CZ) GA14-04338S; GA MŠk(CZ) 7E13003 EU Projects: European Commission(XE) 312495 - SOLARNET Institutional support: RVO:67985815 Keywords : sunspots * magnetic fields * comparison Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 2.682, year: 2016

Optical absorption spectra and g factor of MgO: Mn2+explored by ab initio and semi empirical methods

Science.gov (United States)

Andreici Eftimie, E.-L.; Avram, C. N.; Brik, M. G.; Avram, N. M.

2018-02-01

In this paper we present a methodology for calculations of the optical absorption spectra, ligand field parameters and g factor for the Mn2+ (3d5) ions doped in MgO host crystal. The proposed technique combines two methods: the ab initio multireference (MR) and the semi empirical ligand field (LF) in the framework of the exchange charge model (ECM) respectively. Both methods of calculations are applied to the [MnO6]10-cluster embedded in an extended point charge field of host matrix ligands based on Gellé-Lepetit procedure. The first step of such investigations was the full optimization of the cubic structure of perfect MgO crystal, followed by the structural optimization of the doped of MgO:Mn2+ system, using periodic density functional theory (DFT). The ab initio MR wave functions approaches, such as complete active space self-consistent field (CASSCF), N-electron valence second order perturbation theory (NEVPT2) and spectroscopy oriented configuration interaction (SORCI), are used for the calculations. The scalar relativistic effects have also been taken into account through the second order Douglas-Kroll-Hess (DKH2) procedure. Ab initio ligand field theory (AILFT) allows to extract all LF parameters and spin-orbit coupling constant from such calculations. In addition, the ECM of ligand field theory (LFT) has been used for modelling theoptical absorption spectra. The perturbation theory (PT) was employed for the g factor calculation in the semi empirical LFT. The results of each of the aforementioned types of calculations are discussed and the comparisons between the results obtained and the experimental results show a reasonable agreement, which justifies this new methodology based on the simultaneous use of both methods. This study establishes fundamental principles for the further modelling of larger embedded cluster models of doped metal oxides.

Label Information Guided Graph Construction for Semi-Supervised Learning.

Science.gov (United States)

Zhuang, Liansheng; Zhou, Zihan; Gao, Shenghua; Yin, Jingwen; Lin, Zhouchen; Ma, Yi

2017-09-01

In the literature, most existing graph-based semi-supervised learning methods only use the label information of observed samples in the label propagation stage, while ignoring such valuable information when learning the graph. In this paper, we argue that it is beneficial to consider the label information in the graph learning stage. Specifically, by enforcing the weight of edges between labeled samples of different classes to be zero, we explicitly incorporate the label information into the state-of-the-art graph learning methods, such as the low-rank representation (LRR), and propose a novel semi-supervised graph learning method called semi-supervised low-rank representation. This results in a convex optimization problem with linear constraints, which can be solved by the linearized alternating direction method. Though we take LRR as an example, our proposed method is in fact very general and can be applied to any self-representation graph learning methods. Experiment results on both synthetic and real data sets demonstrate that the proposed graph learning method can better capture the global geometric structure of the data, and therefore is more effective for semi-supervised learning tasks.

A qualitative semi-classical treatment of an isolated semi-polar quantum dot

International Nuclear Information System (INIS)

Young, Toby D

2011-01-01

To qualitatively determine the behaviour of micro-macro properties of a quantum dot grown in a non-polar direction, we propose a simple semi-classical model based on well established ideas. We take into account the following empirical phenomena: (i) The displacement and induced strain at heterojunctions; (ii) The electrostatic potential arising from piezoelectric and spontaneous polarisation; and (iii) The localisation of excitons (particle-hole pairs) arising from quantum confinement. After some algebraic manipulation used to cast the formalism into an arbitrarily rotated frame, a numerical model is developed for the case of a semi-polar wurtzite GaN quantum dot buried in a wurtzite AlN matrix. This scheme is found to provide a satisfying qualitative description of an isolated semi-polar quantum dot in a way that is accessible to further physical interpretation and quantification.

Semi-empirical model for the generation of dose distributions produced by a scanning electron beam

International Nuclear Information System (INIS)

Nath, R.; Gignac, C.E.; Agostinelli, A.G.; Rothberg, S.; Schulz, R.J.

1980-01-01

There are linear accelerators (Sagittaire and Saturne accelerators produced by Compagnie Generale de Radiologie (CGR/MeV) Corporation) which produce broad, flat electron fields by magnetically scanning the relatively narrow electron beam as it emerges from the accelerator vacuum system. A semi-empirical model, which mimics the scanning action of this type of accelerator, was developed for the generation of dose distributions in homogeneous media. The model employs the dose distributions of the scanning electron beams. These were measured with photographic film in a polystyrene phantom by turning off the magnetic scanning system. The mean deviation calculated from measured dose distributions is about 0.2%; a few points have deviations as large as 2 to 4% inside of the 50% isodose curve, but less than 8% outside of the 50% isodose curve. The model has been used to generate the electron beam library required by a modified version of a commercially-available computerized treatment-planning system. (The RAD-8 treatment planning system was purchased from the Digital Equipment Corporation. It is currently available from Electronic Music Industries

Estimating the octanol/water partition coefficient for aliphatic organic compounds using semi-empirical electrotopological index.

Science.gov (United States)

Souza, Erica Silva; Zaramello, Laize; Kuhnen, Carlos Alberto; Junkes, Berenice da Silva; Yunes, Rosendo Augusto; Heinzen, Vilma Edite Fonseca

2011-01-01

A new possibility for estimating the octanol/water coefficient (log P) was investigated using only one descriptor, the semi-empirical electrotopological index (I(SET)). The predictability of four octanol/water partition coefficient (log P) calculation models was compared using a set of 131 aliphatic organic compounds from five different classes. Log P values were calculated employing atomic-contribution methods, as in the Ghose/Crippen approach and its later refinement, AlogP; using fragmental methods through the ClogP method; and employing an approach considering the whole molecule using topological indices with the MlogP method. The efficiency and the applicability of the I(SET) in terms of calculating log P were demonstrated through good statistical quality (r > 0.99; s < 0.18), high internal stability and good predictive ability for an external group of compounds in the same order as the widely used models based on the fragmental method, ClogP, and the atomic contribution method, AlogP, which are among the most used methods of predicting log P.

Emergence of Magnetic Flux Generated in a Solar Convective Dynamo. I. The Formation of Sunspots and Active Regions, and The Origin of Their Asymmetries

Energy Technology Data Exchange (ETDEWEB)

Chen, Feng; Rempel, Matthias; Fan, Yuhong, E-mail: chenfeng@ucar.edu [High Altitude Observatory, NCAR, P.O. Box 3000, Boulder, CO, 80307 (United States)

2017-09-10

We present a realistic numerical model of sunspot and active region formation based on the emergence of flux bundles generated in a solar convective dynamo. To this end, we use the magnetic and velocity fields in a horizontal layer near the top boundary of the solar convective dynamo simulation to drive realistic radiative-magnetohydrodynamic simulations of the uppermost layers of the convection zone. The main results are as follows. (1) The emerging flux bundles rise with the mean speed of convective upflows and fragment into small-scale magnetic elements that further rise to the photosphere, where bipolar sunspot pairs are formed through the coalescence of the small-scale magnetic elements. (2) Filamentary penumbral structures form when the sunspot is still growing through ongoing flux emergence. In contrast to the classical Evershed effect, the inflow seems to prevail over the outflow in a large part of the penumbra. (3) A well-formed sunspot is a mostly monolithic magnetic structure that is anchored in a persistent deep-seated downdraft lane. The flow field outside the spot shows a giant vortex ring that comprises an inflow below 15 Mm depth and an outflow above 15 Mm depth. (4) The sunspots successfully reproduce the fundamental properties of the observed solar active regions, including the more coherent leading spots with a stronger field strength, and the correct tilts of bipolar sunspot pairs. These asymmetries can be linked to the intrinsic asymmetries in the magnetic and flow fields adapted from the convective dynamo simulation.

A Semi-empirical Model of the Stratosphere in the Climate System

Science.gov (United States)

Sodergren, A. H.; Bodeker, G. E.; Kremser, S.; Meinshausen, M.; McDonald, A.

2014-12-01

Chemistry climate models (CCMs) currently used to project changes in Antarctic ozone are extremely computationally demanding. CCM projections are uncertain due to lack of knowledge of future emissions of greenhouse gases (GHGs) and ozone depleting substances (ODSs), as well as parameterizations within the CCMs that have weakly constrained tuning parameters. While projections should be based on an ensemble of simulations, this is not currently possible due to the complexity of the CCMs. An inexpensive but realistic approach to simulate changes in stratospheric ozone, and its coupling to the climate system, is needed as a complement to CCMs. A simple climate model (SCM) can be used as a fast emulator of complex atmospheric-ocean climate models. If such an SCM includes a representation of stratospheric ozone, the evolution of the global ozone layer can be simulated for a wide range of GHG and ODS emissions scenarios. MAGICC is an SCM used in previous IPCC reports. In the current version of the MAGICC SCM, stratospheric ozone changes depend only on equivalent effective stratospheric chlorine (EESC). In this work, MAGICC is extended to include an interactive stratospheric ozone layer using a semi-empirical model of ozone responses to CO2and EESC, with changes in ozone affecting the radiative forcing in the SCM. To demonstrate the ability of our new, extended SCM to generate projections of global changes in ozone, tuning parameters from 19 coupled atmosphere-ocean general circulation models (AOGCMs) and 10 carbon cycle models (to create an ensemble of 190 simulations) have been used to generate probability density functions of the dates of return of stratospheric column ozone to 1960 and 1980 levels for different latitudes.

The incidence of disability pensions and mortality among semi-skilled construction workers in Copenhagen. A retrospective cohort study with two control groups

DEFF Research Database (Denmark)

Damlund, M; Gøth, S; Hasle, P

1982-01-01

The aim of the present study was to discover whether the incidence of disability pensions and mortality was higher amongst semi-skilled construction workers (SCW) in Copenhagen than in two control groups from the same geographic area. The population investigated consisted of a fixed cohort of 353....... Selection bias and the effect of the working environment are discussed against the background of a concurrent investigation of the state of health and working conditions of SCW.......The aim of the present study was to discover whether the incidence of disability pensions and mortality was higher amongst semi-skilled construction workers (SCW) in Copenhagen than in two control groups from the same geographic area. The population investigated consisted of a fixed cohort of 3537...... SCW from Copenhagen as per 1/5/1975. The two control groups comprised 3818 Copenhagen members of the Warehouse Workers' union and a group of Copenhagen members of the Semi-skilled Worker's Union age-matched to the SCW cohort, both as per 1/5/75. Up to 31/12/79, a total of 102 SCW were granted...

Application of the step-wise regression procedure to the semi-empirical formulae of the nuclear binding energy

International Nuclear Information System (INIS)

Eissa, E.A.; Ayad, M.; Gashier, F.A.B.

1984-01-01

Most of the binding energy semi-empirical terms without the deformation corrections used by P.A. Seeger are arranged in a multiple linear regression form. The stepwise regression procedure with 95% confidence levels for acceptance and rejection of variables is applied for seeking a model for calculating binding energies of even-even (E-E) nuclei through a significance testing of each basic term. Partial F-values are taken as estimates for the significance of each term. The residual standard deviation and the overall F-value are used for selecting the best linear regression model. (E-E) nuclei are taken into sets lying between two successive proton and neutron magic numbers. The present work is in favour of the magic number 126 followed by 164 for the neutrons and indecisive in supporting the recently predicted proton magic number 114 rather than the previous one, 126. (author)

Semi-confined compression of microfabricated polymerized biomaterial constructs

International Nuclear Information System (INIS)

Moraes, Christopher; Likhitpanichkul, Morakot; Simmons, Craig A; Sun, Yu; Zhao, Ruogang

2011-01-01

Mechanical forces are critical parameters in engineering functional tissue because of their established influence on cellular behaviour. However, identifying ideal combinations of mechanical, biomaterial and chemical stimuli to obtain a desired cellular response requires high-throughput screening technologies, which may be realized through microfabricated systems. This paper reports on the development and characterization of a MEMS device for semi-confined biomaterial compression. An array of these devices would enable studies involving mechanical deformation of three-dimensional biomaterials, an important parameter in creating physiologically relevant microenvironments in vitro. The described device has the ability to simultaneously apply a range of compressive mechanical stimuli to multiple polymerized hydrogel microconstructs. Local micromechanical strains generated within the semi-confined hydrogel cylinders are characterized and compared with those produced in current micro- and macroscale technologies. In contrast to previous work generating unconfined compression in microfabricated devices, the semi-confined compression model used in this work generates uniform regions of strain within the central portion of each hydrogel, demonstrated here to range from 20% to 45% across the array. The uniform strains achieved simplify experimental analysis and improve the utility of the compression platform. Furthermore, the system is compatible with a wide variety of polymerizable biomaterials, enhancing device versatility and usability in tissue engineering and fundamental cell biology studies

The mutual attraction of magnetic knots. [solar hydromagnetic instability in sunspot regions

Science.gov (United States)

Parker, E. N.

1978-01-01

It is observed that the magnetic knots associated with active regions on the sun have an attraction for each other during the formative period of the active regions, when new magnetic flux is coming to the surface. The attraction disappears when new flux ceases to rise through the surface. Then the magnetic spots and knots tend to come apart, leading to disintegration of the sunspots previously formed. The dissolution of the fields is to be expected, as a consequence of the magnetic repulsion of knots of like polarity and as a consequence of the hydromagnetic exchange instability. The purpose of this paper is to show that the mutual attraction of knots during the formative stages of a sunspot region may be understood as the mutual hydrodynamic attraction of the rising flux tubes. Two rising tubes attract each other, as a consequence of the wake of the leading tube when one is moving behind the other, and as a consequence of the Bernoulli effect when rising side by side.

Building a semi-automatic ontology learning and construction system for geosciences

Science.gov (United States)

Babaie, H. A.; Sunderraman, R.; Zhu, Y.

2013-12-01

We are developing an ontology learning and construction framework that allows continuous, semi-automatic knowledge extraction, verification, validation, and maintenance by potentially a very large group of collaborating domain experts in any geosciences field. The system brings geoscientists from the side-lines to the center stage of ontology building, allowing them to collaboratively construct and enrich new ontologies, and merge, align, and integrate existing ontologies and tools. These constantly evolving ontologies can more effectively address community's interests, purposes, tools, and change. The goal is to minimize the cost and time of building ontologies, and maximize the quality, usability, and adoption of ontologies by the community. Our system will be a domain-independent ontology learning framework that applies natural language processing, allowing users to enter their ontology in a semi-structured form, and a combined Semantic Web and Social Web approach that lets direct participation of geoscientists who have no skill in the design and development of their domain ontologies. A controlled natural language (CNL) interface and an integrated authoring and editing tool automatically convert syntactically correct CNL text into formal OWL constructs. The WebProtege-based system will allow a potentially large group of geoscientists, from multiple domains, to crowd source and participate in the structuring of their knowledge model by sharing their knowledge through critiquing, testing, verifying, adopting, and updating of the concept models (ontologies). We will use cloud storage for all data and knowledge base components of the system, such as users, domain ontologies, discussion forums, and semantic wikis that can be accessed and queried by geoscientists in each domain. We will use NoSQL databases such as MongoDB as a service in the cloud environment. MongoDB uses the lightweight JSON format, which makes it convenient and easy to build Web applications using

A Relationship Between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups

Science.gov (United States)

Ruždjak, Domagoj; Brajša, Roman; Sudar, Davor; Skokić, Ivica; Poljančić Beljan, Ivana

2017-12-01

The sunspot position published in the data bases of the Greenwich Photoheliographic Results (GPR), the US Air Force Solar Optical Observing Network and National Oceanic and Atmospheric Administration (USAF/NOAA), and of the Debrecen Photoheliographic Data (DPD) in the period 1874 to 2016 were used to calculate yearly values of the solar differential-rotation parameters A and B. These differential-rotation parameters were compared with the solar-activity level. We found that the Sun rotates more differentially at the minimum than at the maximum of activity during the epoch 1977 - 2016. An inverse correlation between equatorial rotation and solar activity was found using the recently revised sunspot number. The secular decrease of the equatorial rotation rate that accompanies the increase in activity stopped in the last part of the twentieth century. It was noted that when a significant peak in equatorial rotation velocity is observed during activity minimum, the next maximum is weaker than the previous one.

Analysis of the dative in impersonal constructions: the concepts of subject and semi-subject in ancient Greek

Directory of Open Access Journals (Sweden)

Luz Conti

2010-12-01

Full Text Available Impersonal constructions holding a complement both in dative and genitive are attested in Greek with a few verbs, which share the property of expressing the interests or the needs of human beings. These constructions, which occur in several ancient Indo- European languages, are documented in the post- Homeric period in the case of Greek. In the opposite, personal constructions, which appear more recently in other languages, are already documented in Greek since Homer’s times. The dative in the impersonal construction refers to human entities, codes the Experiencer and it is also the topic. These properties, which are close to those of the prototypical subject, seem to allow the dative to show some subject-like syntactic behaviour. In fact, we will argue that the dative in the impersonal construction behaves as a semi-subject, i. e. a verbal complement which, regardless of its coding, does have a set of properties that are typically associated with the subject in Greek. As well as the complement in dative, the complement in genitive in the impersonal construction exhibits a syntactic behaviour similar to the subject. However, the genitive does not follow the same patterns the dative does in the impersonal construction.

SEMI-EMPIRICAL MODELING OF THE PHOTOSPHERE, CHROMOPSHERE, TRANSITION REGION, AND CORONA OF THE M-DWARF HOST STAR GJ 832

Energy Technology Data Exchange (ETDEWEB)

Fontenla, J. M. [NorthWest Research Associates, Boulder, CO 80301 (United States); Linsky, Jeffrey L. [JILA, University of Colorado and NIST, Boulder, CO 80309-0440 (United States); Witbrod, Jesse [University of Colorado Boulder, CO 80309 (United States); France, Kevin [LASP, University of Colorado Boulder, CO 80309-0600 (United States); Buccino, A.; Mauas, Pablo; Vieytes, Mariela [Instituto de Astronomía y Física del Espacio (CONICET-UBA), C.C. 67, Sucursal 28, C1428EHA, Buenos Aires (Argentina); Walkowicz, Lucianne M., E-mail: johnf@digidyna.com, E-mail: jlinsky@jila.colorado.edu, E-mail: jesse.witbrod@colorado.edu, E-mail: kevin.france@lasp.colorado.edu, E-mail: abuccino@iafe.uba.ar, E-mail: pablo@iafe.uba.ar, E-mail: mariela@iafe.uba.ar, E-mail: LWalkowicz@adlerplanetarium.org [The Adler Planetarium, Chicago, IL 60605 (United States)

2016-10-20

Stellar radiation from X-rays to the visible provides the energy that controls the photochemistry and mass loss from exoplanet atmospheres. The important extreme ultraviolet (EUV) region (10–91.2 nm) is inaccessible and should be computed from a reliable stellar model. It is essential to understand the formation regions and physical processes responsible for the various stellar emission features to predict how the spectral energy distribution varies with age and activity levels. We compute a state-of-the-art semi-empirical atmospheric model and the emergent high-resolution synthetic spectrum of the moderately active M2 V star GJ 832 as the first of a series of models for stars with different activity levels. We construct a one-dimensional simple model for the physical structure of the star’s chromosphere, chromosphere-corona transition region, and corona using non-LTE radiative transfer techniques and many molecular lines. The synthesized spectrum for this model fits the continuum and lines across the UV-to-optical spectrum. Particular emphasis is given to the emission lines at wavelengths that are shorter than 300 nm observed with the Hubble Space Telescope , which have important effects on the photochemistry of the exoplanet atmospheres. The FUV line ratios indicate that the transition region of GJ 832 is more biased to hotter material than that of the quiet Sun. The excellent agreement of our computed EUV luminosity with that obtained by two other techniques indicates that our model predicts reliable EUV emission from GJ 832. We find that the unobserved EUV flux of GJ 832, which heats the outer atmospheres of exoplanets and drives their mass loss, is comparable to the active Sun.

Human semi-supervised learning.

Science.gov (United States)

Gibson, Bryan R; Rogers, Timothy T; Zhu, Xiaojin

2013-01-01

Most empirical work in human categorization has studied learning in either fully supervised or fully unsupervised scenarios. Most real-world learning scenarios, however, are semi-supervised: Learners receive a great deal of unlabeled information from the world, coupled with occasional experiences in which items are directly labeled by a knowledgeable source. A large body of work in machine learning has investigated how learning can exploit both labeled and unlabeled data provided to a learner. Using equivalences between models found in human categorization and machine learning research, we explain how these semi-supervised techniques can be applied to human learning. A series of experiments are described which show that semi-supervised learning models prove useful for explaining human behavior when exposed to both labeled and unlabeled data. We then discuss some machine learning models that do not have familiar human categorization counterparts. Finally, we discuss some challenges yet to be addressed in the use of semi-supervised models for modeling human categorization. Copyright © 2013 Cognitive Science Society, Inc.

HIGH RESOLUTION He i 10830 Å NARROW-BAND IMAGING OF AN M-CLASS FLARE. I. ANALYSIS OF SUNSPOT DYNAMICS DURING FLARING

Energy Technology Data Exchange (ETDEWEB)

Wang, Ya; Su, Yingna; Hong, Zhenxiang; Ji, Haisheng [Key Laboratory of DMSA, Purple Mountain Observatory, CAS, Nanjing, 210008 (China); Zeng, Zhicheng; Goode, Philip R.; Cao, Wenda [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States); Ji, Kaifan [Yunnan Astronomical Observatories, Kunming 650011 (China)

2016-12-20

In this paper, we report our first-step results of high resolution He i 10830 Å narrow-band imaging (bandpass: 0.5 Å) of an M1.8 class two-ribbon flare on 2012 July 5. The flare was observed with the 1.6 m aperture New Solar Telescope at Big Bear Solar Observatory. For this unique data set, sunspot dynamics during flaring were analyzed for the first time. By directly imaging the upper chromosphere, running penumbral waves are clearly seen as an outward extension of umbral flashes; both take the form of absorption in the 10830 Å narrow-band images. From a space–time image made of a slit cutting across a flare ribbon and the sunspot, we find that the dark lanes for umbral flashes and penumbral waves are obviously broadened after the flare. The most prominent feature is the sudden appearance of an oscillating absorption strip inside the ribbon when it sweeps into the sunspot’s penumbral and umbral regions. During each oscillation, outwardly propagating umbral flashes and subsequent penumbral waves rush out into the inwardly sweeping ribbon, followed by a return of the absorption strip with similar speed. We tentatively explain the phenomena as the result of a sudden increase in the density of ortho-helium atoms in the area of the sunspot being excited by the flare’s extreme ultraviolet illumination. This explanation is based on the observation that 10830 Å absorption around the sunspot area gets enhanced during the flare. Nevertheless, questions are still open and we need further well-devised observations to investigate the behavior of sunspot dynamics during flares.

Capital budgeting practices: Empirical evaluation of company practices in the construction sector in Colombia

Directory of Open Access Journals (Sweden)

Julián Ochoa Yepes

2014-12-01

Full Text Available The empirical analysis of capital budgeting or investment appraisal is a topic that has been widely studied in developed countries, such as the United States, the United Kingdom, and Canada. The documentation of these practices in emerging countries is scarce. This paper provides some information about current capital budgeting techniques through an empirical study of practices in a group of Colombian companies in the construction industry. In the companies surveyed it was found that 86% of professionals use the most recommended methods in the literature, such as the Internal Rate of Return (IRR and Net Present Value (NPV, with a preference for the IRR (50% always use it over the NPV (36% always use it. It was also found that 95% lack knowledge of more sophisticated methods, such as Real Options (OR. Most of the respondents subjectively determine the discount rate that is used for evaluation, indicating the lack of any theoretical justification to determine an appropriate rate.

Integrable semi-discretizations of the reduced Ostrovsky equation

International Nuclear Information System (INIS)

Feng, Bao-Feng; Maruno, Ken-ichi; Ohta, Yasuhiro

2015-01-01

Based on our previous work on the reduced Ostrovsky equation (J. Phys. A: Math. Theor. 45 355203), we construct its integrable semi-discretizations. Since the reduced Ostrovsky equation admits two alternative representations, one being its original form, the other the differentiated form (the short wave limit of the Degasperis–Procesi equation) two semi-discrete analogues of the reduced Ostrovsky equation are constructed possessing the same N-loop soliton solution. The relationship between these two versions of semi-discretizations is also clarified. (paper)

Solar magnetic field studies using the 12 micron emission lines. II - Stokes profiles and vector field samples in sunspots

Science.gov (United States)

Hewagama, Tilak; Deming, Drake; Jennings, Donald E.; Osherovich, Vladimir; Wiedemann, Gunter; Zipoy, David; Mickey, Donald L.; Garcia, Howard

1993-01-01

Polarimetric observations at 12 microns of two sunpots are reported. The horizontal distribution of parameters such as magnetic field strength, inclination, azimuth, and magnetic field filling factors are presented along with information about the height dependence of the magnetic field strength. Comparisons with contemporary magnetostatic sunspot models are made. The magnetic data are used to estimate the height of 12 micron line formation. From the data, it is concluded that within a stable sunspot there are no regions that are magnetically filamentary, in the sense of containing both strong-field and field-free regions.

Assessment of radiological parameters and patient dose audit using semi-empirical model

International Nuclear Information System (INIS)

Olowookere, C.J.; Onabiyi, B.; Ajumobi, S. A.; Obed, R.I.; Babalola, I. A.; Bamidele, L.

2011-01-01

Risk is associated with all human activities, medical imaging is no exception. The risk in medical imaging is quantified using effective dose. However, measurement of effective dose is rather difficult and time consuming, therefore, energy imparted and entrance surface dose are obtained and converted into effective dose using the appropriate conversion factors. In this study, data on exposure parameters and patient characteristics were obtained during the routine diagnostic examinations for four common types of X-ray procedures. A semi-empirical model involving computer software Xcomp5 was used to determine energy imparted per unit exposure-area product, entrance skin exposure(ESE) and incident air kerma which are radiation dose indices. The value of energy imparted per unit exposure-area product ranges between 0.60 and 1.21x 10 -3 JR -1 cm -2 and entrance skin exposure range from 5.07±1.25 to 36.62±27.79 mR, while the incident air kerma range between 43.93μGy and 265.5μGy. The filtrations of two of the three machines investigated were lower than the standard requirement of CEC for the machines used in conventional radiography. The values of and ESE obtained in the study were relatively lower compared to the published data, indicating that patients irradiated during the routine examinations in this study are at lower health risk. The energy imparted per unit exposure- area product could be used to determine the energy delivered to the patient during diagnostic examinations, and it is an approximate indicator of patient risk.

Preliminary results from the orbiting solar observatory 8: Transition-zone dynamics over a sunspot

International Nuclear Information System (INIS)

Bruner, E.C. Jr.; Chipman, E.G.; Lites, B.W.; Rottman, G.J.; Shine, R.A.; Athay, R.G.; White, O.R.

1976-01-01

The University of Colorado experiment aboard OSO-8 observed the C IV 1548 A line in the bright plume over a sunspot. Transient redshifts at 5 minute intervals were studied, but the expected phenomena associated with simple Alfven wave effects were not observed

[A competency model of rural general practitioners: theory construction and empirical study].

Science.gov (United States)

Yang, Xiu-Mu; Qi, Yu-Long; Shne, Zheng-Fu; Han, Bu-Xin; Meng, Bei

2015-04-01

To perform theory construction and empirical study of the competency model of rural general practitioners. Through literature study, job analysis, interviews, and expert team discussion, the questionnaire of rural general practitioners competency was constructed. A total of 1458 rural general practitioners were surveyed by the questionnaire in 6 central provinces. The common factors were constructed using the principal component method of exploratory factor analysis and confirmatory factor analysis. The influence of the competency characteristics on the working performance was analyzed using regression equation analysis. The Cronbach 's alpha coefficient of the questionnaire was 0.974. The model consisted of 9 dimensions and 59 items. The 9 competency dimensions included basic public health service ability, basic clinical skills, system analysis capability, information management capability, communication and cooperation ability, occupational moral ability, non-medical professional knowledge, personal traits and psychological adaptability. The rate of explained cumulative total variance was 76.855%. The model fitting index were Χ(2)/df 1.88, GFI=0.94, NFI=0.96, NNFI=0.98, PNFI=0.91, RMSEA=0.068, CFI=0.97, IFI=0.97, RFI=0.96, suggesting good model fitting. Regression analysis showed that the competency characteristics had a significant effect on job performance. The rural general practitioners competency model provides reference for rural doctor training, rural order directional cultivation of medical students, and competency performance management of the rural general practitioners.

Complex network approach to characterize the statistical features of the sunspot series

International Nuclear Information System (INIS)

Zou, Yong; Liu, Zonghua; Small, Michael; Kurths, Jürgen

2014-01-01

Complex network approaches have been recently developed as an alternative framework to study the statistical features of time-series data. We perform a visibility-graph analysis on both the daily and monthly sunspot series. Based on the data, we propose two ways to construct the network: one is from the original observable measurements and the other is from a negative-inverse-transformed series. The degree distribution of the derived networks for the strong maxima has clear non-Gaussian properties, while the degree distribution for minima is bimodal. The long-term variation of the cycles is reflected by hubs in the network that span relatively large time intervals. Based on standard network structural measures, we propose to characterize the long-term correlations by waiting times between two subsequent events. The persistence range of the solar cycles has been identified over 15–1000 days by a power-law regime with scaling exponent γ = 2.04 of the occurrence time of two subsequent strong minima. In contrast, a persistent trend is not present in the maximal numbers, although maxima do have significant deviations from an exponential form. Our results suggest some new insights for evaluating existing models. (paper)

Positioning and Priorities of Growth Management in Construction Industrialization: Chinese Firm-Level Empirical Research

Directory of Open Access Journals (Sweden)

Jingxiao Zhang

2017-06-01

Full Text Available The purpose of this research is to quantitatively evaluate the growth phase, position, and priorities of the industrialization policy management of the construction industry at firm level. The goal is to integrate quantitative dynamics into the policy-making process for sustainable policy development in future China. This research proposes an integrated framework, including growth management model and industrial policy evaluation method, to identify the challenges of construction industrialization and policy management. The research applies the mixed system method, which includes entropy method and average score method, to analyze the growth stage and major impact indexes targeting 327 survey samples. The empirical results show that the proposed conceptual framework and policy evaluation method could effectively determine the growth position and directions of the construction industrialization. For verification purpose, the study uses the local industry data from Shaanxi Province, China. The calculation results substantiate that the construction industry is in the middle section of the third growth phase. The comparison of the results from statistical methods shows that the local construction industry still needs substantial effort in policy management to improve its sustainable industrialization level. As countermeasures, the policy priorities should concentrate on: (1 enhancing effective cooperation among universities, research institutions and enterprises; (2 improving actions towards technology transfer into productivity; and (3 encouraging market acceptance of construction industrialization. This research complements the existing literature of policy evaluation of construction industrialization. Moreover, it provides theoretical and operational steps on industry policy evaluation and growth management framework, with accurate and ample data analysis on firm-level survey. Researchers and policy makers can use this research for further

Semi-empiric model of an air cooled cabinet air conditioner for the dynamic analysis of the building and acclimation systems integrated behaviour; Modelo semi-empirico de condicionador de gabinete resfriado a ar para analise dinamica do comportamento integrado de edificacoes e sistemas de climatizacao

Energy Technology Data Exchange (ETDEWEB)

Correa, Jorge E. [Para Univ., Belem (Brazil). Dept. de Engenharia Mecanica]. E-mail: jecorrea@amazon.com.br; Melo, Claudio. E-mail: melo@nrva.ufsc.br; Negrao, Cezar O. R. E-mail: negrao@energia.damec.cefetpr.br

2000-07-01

This work presents a semi-empirical model for a air cooled case air conditioner. This model is to be inserted in the EPS-r program (Environmental System Performance - research version) allowing the dynamic analysis of the integrated behaviour of buildings and acclimation systems using this equipment. Results obtained from simulations under the operation conditions existing in Brazil are analysed.

Soil Moisture Estimate under Forest using a Semi-empirical Model at P-Band

Science.gov (United States)

Truong-Loi, M.; Saatchi, S.; Jaruwatanadilok, S.

2013-12-01

In this paper we show the potential of a semi-empirical algorithm to retrieve soil moisture under forests using P-band polarimetric SAR data. In past decades, several remote sensing techniques have been developed to estimate the surface soil moisture. In most studies associated with radar sensing of soil moisture, the proposed algorithms are focused on bare or sparsely vegetated surfaces where the effect of vegetation can be ignored. At long wavelengths such as L-band, empirical or physical models such as the Small Perturbation Model (SPM) provide reasonable estimates of surface soil moisture at depths of 0-5cm. However for densely covered vegetated surfaces such as forests, the problem becomes more challenging because the vegetation canopy is a complex scattering environment. For this reason there have been only few studies focusing on retrieving soil moisture under vegetation canopy in the literature. Moghaddam et al. developed an algorithm to estimate soil moisture under a boreal forest using L- and P-band SAR data. For their studied area, double-bounce between trunks and ground appear to be the most important scattering mechanism. Thereby, they implemented parametric models of radar backscatter for double-bounce using simulations of a numerical forest scattering model. Hajnsek et al. showed the potential of estimating the soil moisture under agricultural vegetation using L-band polarimetric SAR data and using polarimetric-decomposition techniques to remove the vegetation layer. Here we use an approach based on physical formulation of dominant scattering mechanisms and three parameters that integrates the vegetation and soil effects at long wavelengths. The algorithm is a simplification of a 3-D coherent model of forest canopy based on the Distorted Born Approximation (DBA). The simplified model has three equations and three unknowns, preserving the three dominant scattering mechanisms of volume, double-bounce and surface for three polarized backscattering

A Semi-Empirical SNR Model for Soil Moisture Retrieval Using GNSS SNR Data

Directory of Open Access Journals (Sweden)

Mutian Han

2018-02-01

Full Text Available The Global Navigation Satellite System-Interferometry and Reflectometry (GNSS-IR technique on soil moisture remote sensing was studied. A semi-empirical Signal-to-Noise Ratio (SNR model was proposed as a curve-fitting model for SNR data routinely collected by a GNSS receiver. This model aims at reconstructing the direct and reflected signal from SNR data and at the same time extracting frequency and phase information that is affected by soil moisture as proposed by K. M. Larson et al. This is achieved empirically through approximating the direct and reflected signal by a second-order and fourth-order polynomial, respectively, based on the well-established SNR model. Compared with other models (K. M. Larson et al., T. Yang et al., this model can improve the Quality of Fit (QoF with little prior knowledge needed and can allow soil permittivity to be estimated from the reconstructed signals. In developing this model, we showed how noise affects the receiver SNR estimation and thus the model performance through simulations under the bare soil assumption. Results showed that the reconstructed signals with a grazing angle of 5°–15° were better for soil moisture retrieval. The QoF was improved by around 45%, which resulted in better estimation of the frequency and phase information. However, we found that the improvement on phase estimation could be neglected. Experimental data collected at Lamasquère, France, were also used to validate the proposed model. The results were compared with the simulation and previous works. It was found that the model could ensure good fitting quality even in the case of irregular SNR variation. Additionally, the soil moisture calculated from the reconstructed signals was about 15% closer in relation to the ground truth measurements. A deeper insight into the Larson model and the proposed model was given at this stage, which formed a possible explanation of this fact. Furthermore, frequency and phase information

WAVES AS THE SOURCE OF APPARENT TWISTING MOTIONS IN SUNSPOT PENUMBRAE

International Nuclear Information System (INIS)

Bharti, L.; Cameron, R. H.; Hirzberger, J.; Solanki, S. K.; Rempel, M.

2012-01-01

The motion of dark striations across bright filaments in a sunspot penumbra has become an important new diagnostic of convective gas flows in penumbral filaments. The nature of these striations has, however, remained unclear. Here, we present an analysis of small-scale motions in penumbral filaments in both simulations and observations. The simulations, when viewed from above, show fine structure with dark lanes running outward from the dark core of the penumbral filaments. The dark lanes either occur preferentially on one side or alternate between both sides of the filament. We identify this fine structure with transverse (kink) oscillations of the filament, corresponding to a sideways swaying of the filament. These oscillations have periods in the range of 5-7 minutes and propagate outward and downward along the filament. Similar features are found in observed G-band intensity time series of penumbral filaments in a sunspot located near disk center obtained by the Broadband Filter Imager on board the Hinode. We also find that some filaments show dark striations moving to both sides of the filaments. Based on the agreement between simulations and observations we conclude that the motions of these striations are caused by transverse oscillations of the underlying bright filaments.

Influence of the sunspot cycle on the Northern Hemisphere wintertime circulation from long upper-air data sets

Directory of Open Access Journals (Sweden)

Y. Brugnara

2013-07-01

Full Text Available Here we present a study of the 11 yr sunspot cycle's imprint on the Northern Hemisphere atmospheric circulation, using three recently developed gridded upper-air data sets that extend back to the early twentieth century. We find a robust response of the tropospheric late-wintertime circulation to the sunspot cycle, independent from the data set. This response is particularly significant over Europe, although results show that it is not directly related to a North Atlantic Oscillation (NAO modulation; instead, it reveals a significant connection to the more meridional Eurasian pattern (EU. The magnitude of mean seasonal temperature changes over the European land areas locally exceeds 1 K in the lower troposphere over a sunspot cycle. We also analyse surface data to address the question whether the solar signal over Europe is temporally stable for a longer 250 yr period. The results increase our confidence in the existence of an influence of the 11 yr cycle on the European climate, but the signal is much weaker in the first half of the period compared to the second half. The last solar minimum (2005 to 2010, which was not included in our analysis, shows anomalies that are consistent with our statistical results for earlier solar minima.

CHROMOSPHERIC MASS MOTIONS AND INTRINSIC SUNSPOT ROTATIONS FOR NOAA ACTIVE REGIONS 10484, 10486, AND 10488 USING ISOON DATA

International Nuclear Information System (INIS)

Hardersen, Paul S.; Balasubramaniam, K. S.; Shkolyar, Svetlana

2013-01-01

This work utilizes Improved Solar Observing Optical Network continuum (630.2 nm) and Hα (656.2 nm) data to: (1) detect and measure intrinsic sunspot rotations occurring in the photosphere and chromosphere, (2) identify and measure chromospheric filament mass motions, and (3) assess any large-scale photospheric and chromospheric mass couplings. Significant results from 2003 October 27-29, using the techniques of Brown et al., indicate significant counter-rotation between the two large sunspots in NOAA AR 10486 on October 29, as well as discrete filament mass motions in NOAA AR 10484 on October 27 that appear to be associated with at least one C-class solar flare

Sunspot variation and selected associated phenomena: a look at solar cycle 21 and beyond

International Nuclear Information System (INIS)

Wilson, R.M.

1982-02-01

Solar sunspot cycles 8 through 21 are reviewed. Mean time intervals are calculated for maximum to maximum, minimum to minimum, minimum to maximum, and maximum to minimum phases for cycles 8 through 20 and 8 through 21. Simple cosine functions with a period of 132 years are compared to, and found to be representative of, the variation of smoothed sunspot numbers at solar maximum and minimum. A comparison of cycles 20 and 21 is given, leading to a projection for activity levels during the Spacelab 2 era (tentatively, November 1984). A prediction is made for cycle 22. Major flares are observed to peak several months subsequent to the solar maximum during cycle 21 and to be at minimum level several months after the solar minimum. Additional remarks are given for flares, gradual rise and fall radio events and 2800 MHz radio emission. Certain solar activity parameters, especially as they relate to the near term Spacelab 2 time frame are estimated

A semi-empirical concept for the calculation of electron-impact ionization cross sections of neutral and ionized fullerenes

International Nuclear Information System (INIS)

Deutsch, H.; Scheier, P.; Maerk, T.D.; Becker, K.

2002-01-01

A semi-empirical approach to the calculation of cross section functions (absolute value and energy dependence) for the electron-impact ionization of several neutral and ionized fullerenes C 60 n+ (n =0-3) was developed, for which reliable experimental data have been reported. In particular, it is proposed a modification of the simplistic assumption that the ionization cross section of a cluster/fullerene is given as the product of the monomer ionization cross section and a factor m a , where 'm' is the number of monomers in the ensemble and 'a' is a constant. A comparison between these calculations and the available experimental data reveals good agreement for n = 0,103. In the case of ionization of C 60 2+ (n = 2) the calculation lies significantly below the measured cross section which it was interpret as an indication that additional indirect ionization processes are present for this charge state. (nevyjel)

On the statistical aspects of sunspot number time series and its association with the summer-monsoon rainfall over India

Science.gov (United States)

Chattopadhyay, Surajit; Chattopadhyay, Goutami

The present paper reports studies on the association between the mean annual sunspot numbers and the summer monsoon rainfall over India. The cross correlations have been studied. After Box-Cox transformation, the time spectral analysis has been executed and it has been found that both of the time series have an important spectrum at the fifth harmonic. An artificial neural network (ANN) model has been developed on the data series averaged continuously by five years and the neural network could establish a predictor-predict and relationship between the sunspot numbers and the mean yearly summer monsoon rainfall over India.

Pharmacological Classification and Activity Evaluation of Furan and Thiophene Amide Derivatives Applying Semi-Empirical ab initio Molecular Modeling Methods

Directory of Open Access Journals (Sweden)

Leszek Bober

2012-05-01

Full Text Available Pharmacological and physicochemical classification of the furan and thiophene amide derivatives by multiple regression analysis and partial least square (PLS based on semi-empirical ab initio molecular modeling studies and high-performance liquid chromatography (HPLC retention data is proposed. Structural parameters obtained from the PCM (Polarizable Continuum Model method and the literature values of biological activity (antiproliferative for the A431 cells expressed as LD₅₀ of the examined furan and thiophene derivatives was used to search for relationships. It was tested how variable molecular modeling conditions considered together, with or without HPLC retention data, allow evaluation of the structural recognition of furan and thiophene derivatives with respect to their pharmacological properties.

Electronic structure prediction via data-mining the empirical pseudopotential method

Energy Technology Data Exchange (ETDEWEB)

Zenasni, H; Aourag, H [LEPM, URMER, Departement of Physics, University Abou Bakr Belkaid, Tlemcen 13000 (Algeria); Broderick, S R; Rajan, K [Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011-2230 (United States)

2010-01-15

We introduce a new approach for accelerating the calculation of the electronic structure of new materials by utilizing the empirical pseudopotential method combined with data mining tools. Combining data mining with the empirical pseudopotential method allows us to convert an empirical approach to a predictive approach. Here we consider tetrahedrally bounded III-V Bi semiconductors, and through the prediction of form factors based on basic elemental properties we can model the band structure and charge density for these semi-conductors, for which limited results exist. This work represents a unique approach to modeling the electronic structure of a material which may be used to identify new promising semi-conductors and is one of the few efforts utilizing data mining at an electronic level. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Flow and magnetic field properties in the trailing sunspots of active region NOAA 12396

Czech Academy of Sciences Publication Activity Database

Verma, M.; Denker, C.; Boehm, F.; Balthasar, H.; Fischer, C.E.; Kuckein, C.; Gonzalez, N.B.; Berkefeld, T.; Collados Vera, M.; Diercke, A.; Feller, A.; Gonzalez Manrique, S. J.; Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pator Yabar, A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, Michal; Solanki, S.K.; Soltau, D.; Staude, J.; Strassmeier, K.G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.A.

2016-01-01

Roč. 337, č. 10 (2016), s. 1090-1098 ISSN 0004-6337. [Dynamic Sun - Exploring the Many Facets of Solar Eruptive Events. Potsdam, 26.10. 2015 -29.10. 2015 ] Institutional support: RVO:67985815 Keywords : Sun * magnetic fields * sunspots Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.916, year: 2016

Determination of the semi-empiric relationship among the physical density, the concentration and rate between hydrogen and manganese atoms, and a manganese sulfate solution; Determinacao da relacao semi-empirica entre a densidade fisica, concentracao e razao entre atomos de hidrogenio e manganes em uma solucao de sulfato de manganes

Energy Technology Data Exchange (ETDEWEB)

Bittencourt, Guilherme Rodrigues [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil). PIBIC; Castro, Leonardo Curvello de; Pereira, Walsan W.; Patrao, Karla C. de Souza; Fonseca, Evaldo S. da; Dantas, Maria Leticia [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Metrologia das Radiacoes Ionizantes (LNMRI). Lab. de Neutrons

2009-07-01

The bath of a manganese sulfate (BMS) is a system for absolute standardization of the neutron sources. This work establishes a functional relationship based on semi-empirical methods for the theoretical prediction of physical density values, concentration and rate between the hydrogen and manganese atoms presents in the solution of the BMS

Neural network consistent empirical physical formula construction for neutron–gamma discrimination in gamma ray tracking

International Nuclear Information System (INIS)

Yildiz, Nihat; Akkoyun, Serkan

2013-01-01

Highlights: ► Detector responses in neutron–gamma discrimination were estimated by neural networks. ► Novel consistent neural network empirical physical formulas (EPFs) were constructed for detector responses. ► The EPFs are of explicit mathematical functional form. ► The EPFs can be used to derive various physical functions relevant to neutron–gamma discrimination in gamma ray tracking. -- Abstract: Gamma ray tracking is an efficient detection technique in studying exotic nuclei which lies far from beta stability line. To achieve very powerful and extraordinary resolution ability, new detectors based on gamma ray tracking are currently being developed. To reach this achievement, the neutron–gamma discrimination in these detectors is also an important task. In this paper, by suitable layered feedforward neural networks (LFNNs), we have constructed novel and consistent empirical physical formulas (EPFs) for some highly nonlinear detector counts measured in neutron–gamma discrimination. The detector counts data used in the discrimination was actually borrowed from our previous paper. The counts used here had been originally measured versus the following parameters: energy deposited in the first interaction points, difference in the incoming direction of initial gamma rays, and finally figure of merit values of the clusters determined by tracking. The LFNN–EPFs are of explicit mathematical functional form. Therefore, by various suitable operations of mathematical analysis, these LFNN–EPFs can be used to derivate further physical functions which might be potentially relevant to neutron–gamma discrimination performance of gamma ray tracking.

The Harm that Underestimation of Uncertainty Does to Our Community: A Case Study Using Sunspot Area Measurements

Science.gov (United States)

Munoz-Jaramillo, Andres

2017-08-01

Data products in heliospheric physics are very often provided without clear estimates of uncertainty. From helioseismology in the solar interior, all the way to in situ solar wind measurements beyond 1AU, uncertainty estimates are typically hard for users to find (buried inside long documents that are separate from the data products), or simply non-existent.There are two main reasons why uncertainty measurements are hard to find:1. Understanding instrumental systematic errors is given a much higher priority inside instrumental teams.2. The desire to perfectly understand all sources of uncertainty postpones indefinitely the actual quantification of uncertainty in our measurements.Using the cross calibration of 200 years of sunspot area measurements as a case study, in this presentation we will discuss the negative impact that inadequate measurements of uncertainty have on users, through the appearance of toxic and unnecessary controversies, and data providers, through the creation of unrealistic expectations regarding the information that can be extracted from their data. We will discuss how empirical estimates of uncertainty represent a very good alternative to not providing any estimates at all, and finalize by discussing the bare essentials that should become our standard practice for future instruments and surveys.

Empirical Test Case Specification

DEFF Research Database (Denmark)

Kalyanova, Olena; Heiselberg, Per

This document includes the empirical specification on the IEA task of evaluation building energy simulation computer programs for the Double Skin Facades (DSF) constructions. There are two approaches involved into this procedure, one is the comparative approach and another is the empirical one. I....... In the comparative approach the outcomes of different software tools are compared, while in the empirical approach the modelling results are compared with the results of experimental test cases....

Empirical Bayes Estimation of Semi-parametric Hierarchical Mixture Models for Unbiased Characterization of Polygenic Disease Architectures

Directory of Open Access Journals (Sweden)

Jo Nishino

2018-04-01

Full Text Available Genome-wide association studies (GWAS suggest that the genetic architecture of complex diseases consists of unexpectedly numerous variants with small effect sizes. However, the polygenic architectures of many diseases have not been well characterized due to lack of simple and fast methods for unbiased estimation of the underlying proportion of disease-associated variants and their effect-size distribution. Applying empirical Bayes estimation of semi-parametric hierarchical mixture models to GWAS summary statistics, we confirmed that schizophrenia was extremely polygenic [~40% of independent genome-wide SNPs are risk variants, most within odds ratio (OR = 1.03], whereas rheumatoid arthritis was less polygenic (~4 to 8% risk variants, significant portion reaching OR = 1.05 to 1.1. For rheumatoid arthritis, stratified estimations revealed that expression quantitative loci in blood explained large genetic variance, and low- and high-frequency derived alleles were prone to be risk and protective, respectively, suggesting a predominance of deleterious-risk and advantageous-protective mutations. Despite genetic correlation, effect-size distributions for schizophrenia and bipolar disorder differed across allele frequency. These analyses distinguished disease polygenic architectures and provided clues for etiological differences in complex diseases.

Infection control in design and construction work.

Science.gov (United States)

Collinge, William H

2015-01-01

To clarify how infection control requirements are represented, communicated, and understood in work interactions through the medical facility construction project life cycle. To assist project participants with effective infection control management by highlighting the nature of such requirements and presenting recommendations to aid practice. A 4-year study regarding client requirement representation and use on National Health Service construction projects in the United Kingdom provided empirical evidence of infection control requirement communication and understanding through design and construction work interactions. An analysis of construction project resources (e.g., infection control regulations and room data sheets) was combined with semi-structured interviews with hospital client employees and design and construction professionals to provide valuable insights into the management of infection control issues. Infection control requirements are representationally indistinct but also omnipresent through all phases of the construction project life cycle: Failure to recognize their nature, relevance, and significance can result in delays, stoppages, and redesign work. Construction project resources (e.g., regulatory guidance and room data sheets) can mask or obscure the meaning of infection control issues. A preemptive identification of issues combined with knowledge sharing activities among project stakeholders can enable infection control requirements to be properly understood and addressed. Such initiatives should also reference existing infection control regulatory guidance and advice. © The Author(s) 2015.

Fully Automated Sunspot Detection and Classification Using SDO HMI Imagery in MATLAB

Science.gov (United States)

2014-03-27

initiating the java program scripted to communicate with the SOON telescope used for continual observation of the sun. The SOON telescope is used at...proximity of spots refers to the angular separation between different spots that could make up a group. The area of each sunspot means the total area...degrees and the different magnetic polarities of each spot being considered. For a spot pair that has the same polarity and small angular separation

Final Empirical Test Case Specification

DEFF Research Database (Denmark)

Kalyanova, Olena; Heiselberg, Per

This document includes the empirical specification on the IEA task of evaluation building energy simulation computer programs for the Double Skin Facades (DSF) constructions. There are two approaches involved into this procedure, one is the comparative approach and another is the empirical one....

Construction and utilization of linear empirical core models for PWR in-core fuel management

International Nuclear Information System (INIS)

Okafor, K.C.

1988-01-01

An empirical core-model construction procedure for pressurized water reactor (PWR) in-core fuel management is developed that allows determining the optimal BOC k ∞ profiles in PWRs as a single linear-programming problem and thus facilitates the overall optimization process for in-core fuel management due to algorithmic simplification and reduction in computation time. The optimal profile is defined as one that maximizes cycle burnup. The model construction scheme treats the fuel-assembly power fractions, burnup, and leakage as state variables and BOC zone enrichments as control variables. The core model consists of linear correlations between the state and control variables that describe fuel-assembly behavior in time and space. These correlations are obtained through time-dependent two-dimensional core simulations. The core model incorporates the effects of composition changes in all the enrichment control zones on a given fuel assembly and is valid at all times during the cycle for a given range of control variables. No assumption is made on the geometry of the control zones. A scatter-composition distribution, as well as annular, can be considered for model construction. The application of the methodology to a typical PWR core indicates good agreement between the model and exact simulation results

STOCHASTIC DESCRIPTION OF THE HIGH-FREQUENCY CONTENT OF DAILY SUNSPOTS AND EVIDENCE FOR REGIME CHANGES

International Nuclear Information System (INIS)

Shapoval, A.; Le Mouël, J.-L.; Courtillot, V.; Shnirman, M.

2015-01-01

The irregularity index λ is applied to the high-frequency content of daily sunspot numbers ISSN. This λ is a modification of the standard maximal Lyapunov exponent. It is computed here as a function of embedding dimension m, within four-year time windows centered at the maxima of Schwabe cycles. The λ(m) curves form separate clusters (pre-1923 and post-1933). This supports a regime transition and narrows its occurrence to cycle 16, preceding the growth of activity leading to the Modern Maximum. The two regimes are reproduced by a simple autoregressive process AR(1), with the mean of Poisson noise undergoing 11 yr modulation. The autocorrelation a of the process (linked to sunspot lifetime) is a ≈ 0.8 for 1850-1923 and ≈0.95 for 1933-2013. The AR(1) model suggests that groups of spots appear with a Poisson rate and disappear at a constant rate. We further applied the irregularity index to the daily sunspot group number series for the northern and southern hemispheres, provided by the Greenwich Royal Observatory (RGO), in order to study a possible desynchronization. Correlations between the north and south λ(m) curves vary quite strongly with time and indeed show desynchronization. This may reflect a slow change in the dimension of an underlying dynamical system. The ISSN and RGO series of group numbers do not imply an identical mechanism, but both uncover a regime change at a similar time. Computation of the irregularity index near the maximum of cycle 24 will help in checking whether yet another regime change is under way

TRANSITION-REGION/CORONAL SIGNATURES AND MAGNETIC SETTING OF SUNSPOT PENUMBRAL JETS: HINODE (SOT/FG), Hi-C, AND SDO/AIA OBSERVATIONS

International Nuclear Information System (INIS)

Tiwari, Sanjiv K.; Moore, Ronald L.; Winebarger, Amy R.; Alpert, Shane E.

2016-01-01

Penumbral microjets (PJs) are transient narrow bright features in the chromosphere of sunspot penumbrae, first characterized by Katsukawa et al. using the Ca ii H-line filter on Hinode's Solar Optical Telescope (SOT). It was proposed that the PJs form as a result of reconnection between two magnetic components of penumbrae (spines and interspines), and that they could contribute to the transition region (TR) and coronal heating above sunspot penumbrae. We propose a modified picture of formation of PJs based on recent results on the internal structure of sunspot penumbral filaments. Using data of a sunspot from Hinode/SOT, High Resolution Coronal Imager, and different passbands of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we examine whether PJs have signatures in the TR and corona. We find hardly any discernible signature of normal PJs in any AIA passbands, except for a few of them showing up in the 1600 Å images. However, we discovered exceptionally stronger jets with similar lifetimes but bigger sizes (up to 600 km wide) occurring repeatedly in a few locations in the penumbra, where evidence of patches of opposite-polarity fields in the tails of some penumbral filaments is seen in Stokes-V images. These tail PJs do display signatures in the TR. Whether they have any coronal-temperature plasma is unclear. We infer that none of the PJs, including the tail PJs, directly heat the corona in active regions significantly, but any penumbral jet might drive some coronal heating indirectly via the generation of Alfvén waves and/or braiding of the coronal field

Development of semi-empirical equations for In-water dose distribution using Co-60 beams

International Nuclear Information System (INIS)

Abdalla, Siddig Abdalla Talha

2001-08-01

Knowledge of absorbed dose distribution is essential for the management of cancer using Co-60 teletherapy. Since direct measurement of dose in patient is impossible, indirect assessments are always carried. In this study direct assessments in phantoms were taken for dose distribution data. Mainly we concentrated on central axis dose and isodose curves data, which are essential for treatment planning. We started by development of a semi-empirical method which uses a more restricted number of measurements and uses graphical relation to develop the dose distribution. This method was based on the decrement lines method which was introduced by Orchard (1964) to develop isodose curve. In the beginning the already developed percent depth dose, Pdd, equation was modified and used to plot the Pdd lines for randomly selected field sizes. After that the dose profiles at depths 5, 10, 15 and 20 cm for randomly selected field sizes were plotted from the direct measurement. Then with the help of the PDD's equation, an equation for the slope of decrement lines is developed. From this slope equation a relation that gives the off axial distance was found. Making use of these relations, the iso lines 80%, 50% and 20% were plotted for the field sizes: 6*6 cm 2 , 10*10 cm 2 and 18*18 cm 2 . Finally these plotted lines were compared to their correspondents from the manufacturer and those used in the hospital (Rick). (Author)

Observations of the birth and fine structure of sunspot penumbrae

International Nuclear Information System (INIS)

Collados, M.; Garcia de la Rosa, J.I.; Moreno-Insertis, F.; Vazquez, M.

1985-01-01

High resolution white-light pictures of sunspot penumbrae are presented. These include pictures showing details of their filamentary structure and some instances of birth of a penumbra. The observations are discussed in the framework of current penumbra theories. A series of pictures have been presented, which give additional evidence of the existence of dark penumbral filaments as individual structures. With respect to the birth of the penumbra some new observational aspects can be seen. The existence of the filamentary penumbra even in the first moments, its non uniformity and its short length are the major aspects derived from the pictures

Benchmarking DFT and semi-empirical methods for a reliable and cost-efficient computational screening of benzofulvene derivatives as donor materials for small-molecule organic solar cells.

Science.gov (United States)

Tortorella, Sara; Talamo, Maurizio Mastropasqua; Cardone, Antonio; Pastore, Mariachiara; De Angelis, Filippo

2016-02-24

A systematic computational investigation on the optical properties of a group of novel benzofulvene derivatives (Martinelli 2014 Org. Lett. 16 3424-7), proposed as possible donor materials in small molecule organic photovoltaic (smOPV) devices, is presented. A benchmark evaluation against experimental results on the accuracy of different exchange and correlation functionals and semi-empirical methods in predicting both reliable ground state equilibrium geometries and electronic absorption spectra is carried out. The benchmark of the geometry optimization level indicated that the best agreement with x-ray data is achieved by using the B3LYP functional. Concerning the optical gap prediction, we found that, among the employed functionals, MPW1K provides the most accurate excitation energies over the entire set of benzofulvenes. Similarly reliable results were also obtained for range-separated hybrid functionals (CAM-B3LYP and wB97XD) and for global hybrid methods incorporating a large amount of non-local exchange (M06-2X and M06-HF). Density functional theory (DFT) hybrids with a moderate (about 20-30%) extent of Hartree-Fock exchange (HFexc) (PBE0, B3LYP and M06) were also found to deliver HOMO-LUMO energy gaps which compare well with the experimental absorption maxima, thus representing a valuable alternative for a prompt and predictive estimation of the optical gap. The possibility of using completely semi-empirical approaches (AM1/ZINDO) is also discussed.

Benchmarking DFT and semi-empirical methods for a reliable and cost-efficient computational screening of benzofulvene derivatives as donor materials for small-molecule organic solar cells

International Nuclear Information System (INIS)

Tortorella, Sara; Talamo, Maurizio Mastropasqua; Cardone, Antonio; Pastore, Mariachiara; De Angelis, Filippo

2016-01-01

A systematic computational investigation on the optical properties of a group of novel benzofulvene derivatives (Martinelli 2014 Org. Lett. 16 3424–7), proposed as possible donor materials in small molecule organic photovoltaic (smOPV) devices, is presented. A benchmark evaluation against experimental results on the accuracy of different exchange and correlation functionals and semi-empirical methods in predicting both reliable ground state equilibrium geometries and electronic absorption spectra is carried out. The benchmark of the geometry optimization level indicated that the best agreement with x-ray data is achieved by using the B3LYP functional. Concerning the optical gap prediction, we found that, among the employed functionals, MPW1K provides the most accurate excitation energies over the entire set of benzofulvenes. Similarly reliable results were also obtained for range-separated hybrid functionals (CAM-B3LYP and wB97XD) and for global hybrid methods incorporating a large amount of non-local exchange (M06-2X and M06-HF). Density functional theory (DFT) hybrids with a moderate (about 20–30%) extent of Hartree–Fock exchange (HFexc) (PBE0, B3LYP and M06) were also found to deliver HOMO–LUMO energy gaps which compare well with the experimental absorption maxima, thus representing a valuable alternative for a prompt and predictive estimation of the optical gap. The possibility of using completely semi-empirical approaches (AM1/ZINDO) is also discussed. (paper)

Sunspots and the physics of magnetic flux tubes in the sun

International Nuclear Information System (INIS)

Ballegooijen, A.A. van.

1982-01-01

This thesis refers to the sub-surface structure of the solar magnetic field. Following an introductory chapter, chapter II presents an analysis of spectroscopic observations of a sunspot at infrared wavelengths and models of the temperature stratification in the sunspot atmosphere are derived. The main subject of this thesis concerns the structure of the magnetic field deep down below the stellar surface, near the base of the convective envelope. In Chapter III the stability of toroidal flux tubes to wave-like perturbations is discussed, assuming that the tubes are neutrally buoyant. A model is proposed in which the toroidal flux tubes are neutrally buoyant and located in a stably stratified layer just below the base of the convective zone. On the basis of some simple assumptions for the temperature stratification in this storage layer the author considers in Chapter IV the properties of the vertical flux tubes in the convective zone. The adiabatic flux model cannot satisfactorily be applied to the simplified model of the storage layer, so that the problem of magnetic flux storage is reconsidered in Chapter V. A new model of the temperature stratification at the interface of convective zone and radiative interior of the sun is described. Finally, in Chapter VI, the stability of toroidal flux tubes in a differentially rotating star are discussed. It is demonstrated that for realistic values of the magnetic field strength, rotation has a strong effect on the stability of the toroidal flux tubes. (C.F.)

Sunspots and the physics of magnetic flux tubes. II. Aerodynamic drag

International Nuclear Information System (INIS)

Parker, E.N.

1979-01-01

The aerodynamic drag on a slender flux tube stretched vertically across a convective cell may push the flux tube into the updrafts or into the downdrafts, depending on the density stratification of the convecting fluid and the asymmetry of the fluid motions. The drag is approximately proportional to the local kinetic energy density, so the density stratification weights the drag in favor of the upper layers where the density is low, tending to push the vertical tube into the downdrafts. If, however, the horizontal motions in the convective cell are concentrated toward the bottom of the cell, they may dominate over the upper layers, pushing the tube into the updrafts. In the simple, idealized circumstance of a vertical tube extending across a fluid of uniform density in a convective cell that is symmetric about its midplane, the net aerodynamic drag vanishes in lowest order. The higher order contributions, including the deflection of the tube, then provide a nonvanishing force pushing the tube into a stable equilibrium midway between the updraft and the downdraft.It is pointed out that in the strongly stratified convective zone of the Sun, a downdraft herds flux tubes together into a cluster, while an updraft disperses them. To account for the observed strong cohesion of the cluster of flux tubes that make up a sunspot, we propose a downdraft of the order 2 km s - 1 through the cluster of seprate tubes beneath the sunspot

Initial phase of the development of sunspot groups and their forecast

International Nuclear Information System (INIS)

Berlyand, B.O.; Burov, V.A.; Stepanyan, N.N.

1979-01-01

Some characteristics of the initial phase of sunspot groups and their forecast have been considered. Experimental data on 340 sunspot groups were obtained in 1967-1969. It was found that oscillations of the magnetic flux in the groups indicate the possibility of the existence of typical periods (2 and 4 days) of the magnetic field development. Most of the groups appears in young plages. The probability of the protons injection from the young groups is very small. The typical time of the development of the proton centre is 10-30 days. The characteristics of the group on the first day of its existence are vaguely connected with the lifetime of the group. On the second and third days the magnetic characteristics (the summary magnetic flux and the number of the unipolar regions) have the highest correlation coefficient (approximately 70%) with the lifetime of the group. The problem of the group lifetime forecast was being solved with the pattern recognition technique. On the base of the second day observation of the existence of the group verification of the received forecast 14% exceeds the verification of the climatological forecast. The forecast of the Zurich class with the same technique is effective beginning with the fifth day of the group existence and the forecast of the flare activity of the group since the day of its appearance. The exceeding of the verification as compared with the climatological forecasts in these problems is 10% and 8% accordingly

Intermolecular interactions in the condensed phase: Evaluation of semi-empirical quantum mechanical methods.

Science.gov (United States)

Christensen, Anders S; Kromann, Jimmy C; Jensen, Jan H; Cui, Qiang

2017-10-28

To facilitate further development of approximate quantum mechanical methods for condensed phase applications, we present a new benchmark dataset of intermolecular interaction energies in the solution phase for a set of 15 dimers, each containing one charged monomer. The reference interaction energy in solution is computed via a thermodynamic cycle that integrates dimer binding energy in the gas phase at the coupled cluster level and solute-solvent interaction with density functional theory; the estimated uncertainty of such calculated interaction energy is ±1.5 kcal/mol. The dataset is used to benchmark the performance of a set of semi-empirical quantum mechanical (SQM) methods that include DFTB3-D3, DFTB3/CPE-D3, OM2-D3, PM6-D3, PM6-D3H+, and PM7 as well as the HF-3c method. We find that while all tested SQM methods tend to underestimate binding energies in the gas phase with a root-mean-squared error (RMSE) of 2-5 kcal/mol, they overestimate binding energies in the solution phase with an RMSE of 3-4 kcal/mol, with the exception of DFTB3/CPE-D3 and OM2-D3, for which the systematic deviation is less pronounced. In addition, we find that HF-3c systematically overestimates binding energies in both gas and solution phases. As most approximate QM methods are parametrized and evaluated using data measured or calculated in the gas phase, the dataset represents an important first step toward calibrating QM based methods for application in the condensed phase where polarization and exchange repulsion need to be treated in a balanced fashion.

Intermolecular interactions in the condensed phase: Evaluation of semi-empirical quantum mechanical methods

Science.gov (United States)

Christensen, Anders S.; Kromann, Jimmy C.; Jensen, Jan H.; Cui, Qiang

2017-10-01

To facilitate further development of approximate quantum mechanical methods for condensed phase applications, we present a new benchmark dataset of intermolecular interaction energies in the solution phase for a set of 15 dimers, each containing one charged monomer. The reference interaction energy in solution is computed via a thermodynamic cycle that integrates dimer binding energy in the gas phase at the coupled cluster level and solute-solvent interaction with density functional theory; the estimated uncertainty of such calculated interaction energy is ±1.5 kcal/mol. The dataset is used to benchmark the performance of a set of semi-empirical quantum mechanical (SQM) methods that include DFTB3-D3, DFTB3/CPE-D3, OM2-D3, PM6-D3, PM6-D3H+, and PM7 as well as the HF-3c method. We find that while all tested SQM methods tend to underestimate binding energies in the gas phase with a root-mean-squared error (RMSE) of 2-5 kcal/mol, they overestimate binding energies in the solution phase with an RMSE of 3-4 kcal/mol, with the exception of DFTB3/CPE-D3 and OM2-D3, for which the systematic deviation is less pronounced. In addition, we find that HF-3c systematically overestimates binding energies in both gas and solution phases. As most approximate QM methods are parametrized and evaluated using data measured or calculated in the gas phase, the dataset represents an important first step toward calibrating QM based methods for application in the condensed phase where polarization and exchange repulsion need to be treated in a balanced fashion.

Evaluation of three semi-empirical approaches to estimate the net radiation over a drip-irrigated olive orchard

Directory of Open Access Journals (Sweden)

Rafael López-Olivari

2015-09-01

Full Text Available The use of actual evapotranspiration (ETα models requires an appropriate parameterization of the available energy, where the net radiation (Rn is the most important component. Thus, a study was carried out to calibrate and evaluate three semi-empirical approaches to estimate net radiation (Rn over a drip-irrigated olive (Olea europaea L. 'Arbequina' orchard during 2009/2010 and 2010/2011 seasons. The orchard was planted in 2005 at high density in the Pencahue Valley, Maule Region, Chile. The evaluated models were calculated using the balance between long and short wave radiation. To achieve this objective it was assumed that Ts = Tα for Model 1, Ts = Tv for Model 2 and Ts = Tr for Model 3 (Ts is surface temperature; Tα is air temperature; and Tv is temperature inside of the tree canopy; Tr is radiometric temperature. For the three models, the Brutsaert's empirical coefficient (Φ was calibrated using incoming long wave radiation equation with the database of 2009/2010 season. Thus, the calibration indicated that Φ was equal to 1.75. Using the database from 2010/2011 season, the validation indicated that the three models were able to predict the Rn at a 30-min interval with errors lower than 6%, root mean square error (RMSE between 26 and 39 W m-2 and mean absolute error (MAE between 20 and 31 W m-2. On daily time intervals, validation indicated that models presented errors, RMSE and MAE between 2% and 3%, 1.22-1.54 and 1.04-1.35 MJ m-2 d-1, respectively. The three R„-Models would be evaluated and used in others Mediterranean conditions according to the availability of data to estimate net radiation over a drip-irrigated olive orchard planted at high density.

TILT ANGLE AND FOOTPOINT SEPARATION OF SMALL AND LARGE BIPOLAR SUNSPOT REGIONS OBSERVED WITH HMI

International Nuclear Information System (INIS)

McClintock, B. H.; Norton, A. A.

2016-01-01

We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager—Debrecen Data with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within ±96 hr of time zero. Tilt angle evolution is distinctly different for regions with small (≈30 MSH), midsize (≈50 MSH), and large (≈110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions for separating the groups. At the peak umbral area, we determine median tilt angles for small (7.°6), midsize (5.°9), and large (9.°3) regions. Within ±48 hr of the time of peak umbral area, large regions steadily increase in tilt angle, midsize regions are nearly constant, and small regions show evidence of negative tilt during emergence. A period of growth in footpoint separation occurs over a 72-hr period for all of the regions from roughly 40 to 70 Mm. The smallest bipoles (<9 MSH) are outliers in that they do not obey Joy's law and have a much smaller footpoint separation. We confirm the Muñoz-Jaramillo et al. results that the sunspots appear to be two distinct populations

An empirical study of ensemble-based semi-supervised learning approaches for imbalanced splice site datasets.

Science.gov (United States)

Stanescu, Ana; Caragea, Doina

2015-01-01

Recent biochemical advances have led to inexpensive, time-efficient production of massive volumes of raw genomic data. Traditional machine learning approaches to genome annotation typically rely on large amounts of labeled data. The process of labeling data can be expensive, as it requires domain knowledge and expert involvement. Semi-supervised learning approaches that can make use of unlabeled data, in addition to small amounts of labeled data, can help reduce the costs associated with labeling. In this context, we focus on the problem of predicting splice sites in a genome using semi-supervised learning approaches. This is a challenging problem, due to the highly imbalanced distribution of the data, i.e., small number of splice sites as compared to the number of non-splice sites. To address this challenge, we propose to use ensembles of semi-supervised classifiers, specifically self-training and co-training classifiers. Our experiments on five highly imbalanced splice site datasets, with positive to negative ratios of 1-to-99, showed that the ensemble-based semi-supervised approaches represent a good choice, even when the amount of labeled data consists of less than 1% of all training data. In particular, we found that ensembles of co-training and self-training classifiers that dynamically balance the set of labeled instances during the semi-supervised iterations show improvements over the corresponding supervised ensemble baselines. In the presence of limited amounts of labeled data, ensemble-based semi-supervised approaches can successfully leverage the unlabeled data to enhance supervised ensembles learned from highly imbalanced data distributions. Given that such distributions are common for many biological sequence classification problems, our work can be seen as a stepping stone towards more sophisticated ensemble-based approaches to biological sequence annotation in a semi-supervised framework.

Observations of the longitudinal magnetic field in the transition region and photosphere of a sunspot

Science.gov (United States)

Henze, W., Jr.; Tandberg-Hanssen, E.; Hagyard, M. J.; West, E. A.; Woodgate, B. E.; Shine, R. A.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; West, E. A.

1982-01-01

The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacraft has observed for the first time the longitudinal component of the magnetic field by means of the Zeeman effect in the transition region above a sunspot. The data presented here were obtained on three days in one sunspot, have spatial resolutions of 10 arcsec and 3 arcsec, and yield maximum field strengths greater than 1000 G above the umbrae in the spot. The method of analysis, including a line-width calibration feature used during some of the observations, is described in some detail in an appendix; the line width is required for the determination of the longitudinal magnetic field from the observed circular polarization. The transition region data for one day are compared with photospheric magnetograms from the Marshall Space Flight Center. Vertical gradients of the magnetic field are compared from the two sets of data; the maximum gradients of 0.41 to 0.62 G/km occur above the umbra and agree with or are smaller than values observed previously in the photosphere and low chromosphere.

The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere

Energy Technology Data Exchange (ETDEWEB)

Prasad, S. Krishna; Jess, D. B. [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, BT7 1NN (United Kingdom); Doorsselaere, T. Van [Centre for mathematical Plasma Astrophysics, Mathematics Department, KU Leuven, Celestijnenlaan 200B bus 2400, B-3001 Leuven (Belgium); Verth, G. [School of Mathematics and Statistics, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH (United Kingdom); Morton, R. J. [Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Ellison Building, Newcastle upon Tyne, NE1 8ST (United Kingdom); Fedun, V. [Department of Automatic Control and Systems Engineering, University of Sheffield, Sheffield, S1 3JD (United Kingdom); Erdélyi, R. [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH (United Kingdom); Christian, D. J., E-mail: krishna.prasad@qub.ac.uk [Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330 (United States)

2017-09-20

High spatial and temporal resolution images of a sunspot, obtained simultaneously in multiple optical and UV wavelengths, are employed to study the propagation and damping characteristics of slow magnetoacoustic waves up to transition region heights. Power spectra are generated from intensity oscillations in sunspot umbra, across multiple atmospheric heights, for frequencies up to a few hundred mHz. It is observed that the power spectra display a power-law dependence over the entire frequency range, with a significant enhancement around 5.5 mHz found for the chromospheric channels. The phase difference spectra reveal a cutoff frequency near 3 mHz, up to which the oscillations are evanescent, while those with higher frequencies propagate upward. The power-law index appears to increase with atmospheric height. Also, shorter damping lengths are observed for oscillations with higher frequencies suggesting frequency-dependent damping. Using the relative amplitudes of the 5.5 mHz (3 minute) oscillations, we estimate the energy flux at different heights, which seems to decay gradually from the photosphere, in agreement with recent numerical simulations. Furthermore, a comparison of power spectra across the umbral radius highlights an enhancement of high-frequency waves near the umbral center, which does not seem to be related to magnetic field inclination angle effects.

NUMERICAL SIMULATIONS OF CONVERSION TO ALFVÉN WAVES IN SUNSPOTS

International Nuclear Information System (INIS)

Khomenko, E.; Cally, P. S.

2012-01-01

We study the conversion of fast magnetoacoustic waves to Alfvén waves by means of 2.5D numerical simulations in a sunspot-like magnetic configuration. A fast, essentially acoustic, wave of a given frequency and wave number is generated below the surface and propagates upward through the Alfvén/acoustic equipartition layer where it splits into upgoing slow (acoustic) and fast (magnetic) waves. The fast wave quickly reflects off the steep Alfvén speed gradient, but around and above this reflection height it partially converts to Alfvén waves, depending on the local relative inclinations of the background magnetic field and the wavevector. To measure the efficiency of this conversion to Alfvén waves we calculate acoustic and magnetic energy fluxes. The particular amplitude and phase relations between the magnetic field and velocity oscillations help us to demonstrate that the waves produced are indeed Alfvén waves. We find that the conversion to Alfvén waves is particularly important for strongly inclined fields like those existing in sunspot penumbrae. Equally important is the magnetic field orientation with respect to the vertical plane of wave propagation, which we refer to as 'field azimuth'. For a field azimuth less than 90° the generated Alfvén waves continue upward, but above 90° downgoing Alfvén waves are preferentially produced. This yields negative Alfvén energy flux for azimuths between 90° and 180°. Alfvén energy fluxes may be comparable to or exceed acoustic fluxes, depending upon geometry, though computational exigencies limit their magnitude in our simulations.

Design of semi-rigid type of flexible pavements

Directory of Open Access Journals (Sweden)

Pranshoo Solanki

2017-03-01

Full Text Available The primary objective of the study presented in this paper is to develop design curves for performance prediction of stabilized layers and to compare semi-rigid flexible pavement designs between the empirical AASHTO 1993 and the mechanistic-empirical pavement design methodologies. Specifically, comparisons were made for a range of different sections consisting of cementitious layers stabilized with different types and percentages of additives. It is found that the design thickness is influenced by the type of soil, additive, selection of material property and design method. Cost comparisons of sections stabilized with different percentage and type of additives showed that CKD-stabilization provides economically low cost sections as compared to lime- and CFA-stabilized sections. Knowledge gained from the parametric analysis of different sections using AASHTO 1993 and MEPDG is expected to be useful to pavement designers and others in implementation of the new MEPDG for future pavement design. Keywords: Semi-rigid, Mechanistic, Resilient modulus, Fatigue life, Reliability, Traffic

Semi-empirical simulation of thermoluminescent response under different filter geometries; Simulacao semi-empirica da resposta termoluminescente sob diferentes geometrias de filtro

Energy Technology Data Exchange (ETDEWEB)

Shammas, Gabriel Issa Jabra

2006-07-01

Many thermoluminescent materials has been developed and used for photon personal dosimetry but no one has all desired characteristics alone. These characteristics include robustness, high sensitivity, energy photon independence, large range of photon energy detection, good reproducibility, small fading and simple glow curve with peaks above 150 deg C. Calcium Sulfate Dysprosium doped (CaSO{sub 4}:Dy) phosphor Thermoluminescent Dosimeter (TLD) has been used by many laboratories, mainly in Brazil and India. Another interesting phosphor is Calcium Fluoride (CaF{sub 2}). These phosphor advantages begin to be more required and its disadvantages have became more apparent, in a global market more and more competitive. These phosphors are used in environmental and area monitoring, once they present more sensibility than other phosphors, like LiF:Mg. Theirs mainly disadvantage is a strong energetic dependence response, which must be corrected for theirs application in the field, where photon radiation is unknown a priori. An interesting way do make this correction in orthogonal incidence of the radiation on the phosphor is to interject a plane leaked filter between the beam and the phosphor. In order to reduce the energetic dependence on any incidence angle, reducing the field dose measurement uncertainty too, this work presents a simulation study on spherical filter geometries. It was simulated photon irradiations with Gamma rays of {sup 60}Co and x-rays of 33; 48 and 118 keV, on many incidence angles from zero to ninety degrees. These semi-empirical computational simulations using finite differences in three dimensions were done in spherical coordinates. The results pointed out the best filter thicknesses and widths, in order to optimize the correction on energetic dependence. (author)

Umbral oscillations as a probe of sunspot

International Nuclear Information System (INIS)

Abdelatif, T.E.H.

1985-01-01

The interaction of the solar five-minute oscillations with a sunspot is thoroughly explored, both on observational and theoretical grounds. Simple theoretical models are developed in order to understand the observations of umbral oscillations. Observations made at the National Solar Observatory detected both the three-minute and five-minute umbral oscillations at photospheric heights. The three-minute oscillations were found to have a kinetic energy density six times higher in the photosphere than in the chromosphere and to be concentrated in the central part of the umbra, supporting the photospheric resonance theory for the three-minute umbral oscillations. The five-minute oscillations are attenuated in the umbra, which appears to act as a filter in selecting some of the peaks in the power spectrum of five-minute oscillations in the surrounding photosphere. The k-omega power spectrum of the umbral oscillations shows a shift of power to longer wavelengths. Theoretical models of the transmission of acoustic waves into a magnetic region explain both observed effects

A semi-Markov model for the duration of stay in a non-homogenous ...

African Journals Online (AJOL)

The semi-Markov approach to a non-homogenous manpower system is considered. The mean duration of stay in a grade and the total duration of stay in the system are obtained. A renewal type equation is developed and used in deriving the limiting distribution of the semi – Markov process. Empirical estimators of the ...

Surge-like Oscillations above Sunspot Light Bridges Driven by Magnetoacoustic Shocks

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jingwen; Tian, Hui; He, Jiansen; Wang, Linghua, E-mail: huitian@pku.edu.cn [School of Earth and Space Sciences, Peking University, 100871 Beijing (China)

2017-03-20

High-resolution observations of the solar chromosphere and transition region often reveal surge-like oscillatory activities above sunspot light bridges (LBs). These oscillations are often interpreted as intermittent plasma jets produced by quasi-periodic magnetic reconnection. We have analyzed the oscillations above an LB in a sunspot using data taken by the Interface Region Imaging Spectrograph . The chromospheric 2796 Å images show surge-like activities above the entire LB at any time, forming an oscillating wall. Within the wall we often see that the core of the Mg ii k 2796.35 Å line first experiences a large blueshift, and then gradually decreases to zero shift before increasing to a redshift of comparable magnitude. Such a behavior suggests that the oscillations are highly nonlinear and likely related to shocks. In the 1400 Å passband, which samples emission mainly from the Si iv ion, the most prominent feature is a bright oscillatory front ahead of the surges. We find a positive correlation between the acceleration and maximum velocity of the moving front, which is consistent with numerical simulations of upward propagating slow-mode shock waves. The Si iv 1402.77 Å line profile is generally enhanced and broadened in the bright front, which might be caused by turbulence generated through compression or by the shocks. These results, together with the fact that the oscillation period stays almost unchanged over a long duration, lead us to propose that the surge-like oscillations above LBs are caused by shocked p-mode waves leaked from the underlying photosphere.

Semi empirical model for astrophysical nuclear fusion reactions of 1≤Z≤15

International Nuclear Information System (INIS)

Manjunatha, H.C.; Seenappa, L.; Sridhar, K.N.

2017-01-01

The fusion reaction is one of the most important reactions in the stellar evolution. Due to the complicated reaction mechanism of fusion, there is great uncertainty in the reaction rate which limits our understanding of various stellar objects. Low z elements are formed through many fusion reactions such as "4He+"1"2C→"1"6O, "1"2C+"1"2C→"2"0Ne+"4He, "1"2C+"1"2C→"2"3Na, "1"2C+"1"2C→"2"3Mg, "1"6O+"1"6O→"2"8Si+"4He, "1"2C+"1H→"1"3N and "1"3C+"4He→"1"6O. A detail study is required on Coulomb and nuclear interaction in formation of low Z elements in stars through fusion reactions. For astrophysics, the important energy range extends from 1 MeV to 3 MeV in the center of mass frame, which is only partially covered by experiments. In the present work, we have studied the basic fusion parameters such as barrier heights (V_B), positions (R_B), curvature of the inverted parabola (ħω_1) for fusion barrier, cross section and compound nucleus formation probability (P_C_N) and fusion process in the low Z element (1≤Z≤15) formation process. For each isotope, we have studied all possible projectile-target combinations. We have also studied the astrophysical S(E) factor for these reactions. Based on this study, we have formulated the semi empirical relations for barrier heights (V_B), positions (R_B), curvature of the inverted parabola and hence for the fusion cross section and astrophysical S(E) factor. The values produced by the present model compared with the experiments and data available in the literature. (author)

Values of Kp Indices, Ap Indices, Cp Indices, C9 Indices, Sunspot Number, and 10.7 cm Flux

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data file consists of Kp indices, Ap indices, Cp indices, C9 indices, sunspot number, and 10.7 cm flux. The most often requested parameter of this file are the...

Semi-Empiric Algorithm for Assessment of the Vehicle Mobility

Directory of Open Access Journals (Sweden)

Ticusor CIOBOTARU

2009-12-01

Full Text Available The mobility of military vehicles plays a key role in operation. The ability to reach the desired area in war theatre represents the most important condition for a successful accomplishment of the mission for military vehicles. The off-road vehicles face a broad spectrum of terrains to cross. These terrains differ by geometry and the soil characteristics.NATO References Mobility Model (NRMM software is based on empirical relationship between the terrain characteristics, running conditions and vehicles design. The paper presents the main results of a comparative mobility analysis for M1 and HMMWV vehicles obtained using NRMM.

Construction of Fine Particles Source Spectrum Bank in Typical Region and Empirical Research of Matching Diagnosis

Science.gov (United States)

Wang, Xing; Sun, Wenliang; Guo, Min; Li, Minjiao; Li, Wan

2018-01-01

The research object of this paper is fine particles in typical region. The construction of component spectrum bank is based on the technology of online source apportionment, then the result of the apportionment is utilized to verify the effectiveness of fine particles component spectrum bank and which also act as the matching basis of online source apportionment receptor sample. On the next, the particle source of air pollution is carried through the matching diagnosis empirical research by utilizing online source apportionment technology, to provide technical support for the cause analysis and treatment of heavy pollution weather.

Estimation with Right-Censored Observations Under A Semi-Markov Model.

Science.gov (United States)

Zhao, Lihui; Hu, X Joan

2013-06-01

The semi-Markov process often provides a better framework than the classical Markov process for the analysis of events with multiple states. The purpose of this paper is twofold. First, we show that in the presence of right censoring, when the right end-point of the support of the censoring time is strictly less than the right end-point of the support of the semi-Markov kernel, the transition probability of the semi-Markov process is nonidentifiable, and the estimators proposed in the literature are inconsistent in general. We derive the set of all attainable values for the transition probability based on the censored data, and we propose a nonparametric inference procedure for the transition probability using this set. Second, the conventional approach to constructing confidence bands is not applicable for the semi-Markov kernel and the sojourn time distribution. We propose new perturbation resampling methods to construct these confidence bands. Different weights and transformations are explored in the construction. We use simulation to examine our proposals and illustrate them with hospitalization data from a recent cancer survivor study.

Development of Instruments to Assess Shame and Guilt in Adolescents: Empirical Differences Between the Constructs

Directory of Open Access Journals (Sweden)

Lorena Maria Laskoski

2013-05-01

Full Text Available Shame and guilt are terms easily mixed in everyday life and often used as synonyms. Although they are words of similar use, they represent theoretically different moral emotions. The aims of this study were to develop and validate instruments to assess shame and guilt and to test the empirical independence of the constructs. Five hundred and eighty high school students from three Brazilian states participated in this study, 55% of them female, with an average age of 16.0 years. The participants answered a questionnaire containing socio demographic questions and scales designed for this study in order to assess shame and guilt. The scales developed gave appropriate evidence of validity and reliability. A single factor was extracted to assess shame and two factors to assess guilt (recognition of mistake and regret. The constructs revealed to be correlated, but independent. It is considered that there is sufficient evidence to affirm that shame and guilt are emotions with distinctive peculiarities and can be measured using the instruments developed in this research.

Using dynamo theory to predict the sunspot number during solar cycle 21

Science.gov (United States)

Schatten, K. H.; Scherrer, P. H.; Svalgaard, L.; Wilcox, J. M.

1978-01-01

On physical grounds it is suggested that the polar field strength of the sun near a solar minimum is closely related to the solar activity of the following cycle. Four methods of estimating the polar magnetic field strength of the sun near solar minimum are employed to provide an estimate of the yearly mean sunspot number of cycle 21 at solar maximum of 140 + or - 20. This estimate may be considered a first-order attempt to predict the cycle activity using one parameter of physical importance based upon dynamo theory.

Construction of a technological semi-digital hadronic calorimeter using GRPC

International Nuclear Information System (INIS)

Laktineh, I

2011-01-01

A high-granularity semi-digital Hadronic calorimeter using GRPC as sensitive medium is one of the two HCAL options considered by the ILD collaboration to be proposed for the detector of the future International Linear Collider project. A prototype of 1 m 3 has been conceived within the CALICE collaboration in order to validate this option. The prototype intends to be as close as possible to the one proposed in the ILD Letter Of Intent. Few units made of 1m 2 GRPC fully equipped with semi-digital readout electronics and new gas distribution design were produced and successfully tested. In 2010 we intend to produce 40 similar units to be inserted in a self-supporting mechanical structure. The prototype will then be exposed to TestBeams at CERN for final validation.

Construction of a technological semi-digital hadronic calorimeter using GRPC

Science.gov (United States)

Laktineh, I.

2011-04-01

A high-granularity semi-digital Hadronic calorimeter using GRPC as sensitive medium is one of the two HCAL options considered by the ILD collaboration to be proposed for the detector of the future International Linear Collider project. A prototype of 1m3 has been conceived within the CALICE collaboration in order to validate this option. The prototype intends to be as close as possible to the one proposed in the ILD Letter Of Intent. Few units made of 1m2 GRPC fully equipped with semi-digital readout electronics and new gas distribution design were produced and successfully tested. In 2010 we intend to produce 40 similar units to be inserted in a self-supporting mechanical structure. The prototype will then be exposed to TestBeams at CERN for final validation.

Optimizing irrigation and nitrogen for wheat through empirical modeling under semi-arid environment.

Science.gov (United States)

Saeed, Umer; Wajid, Syed Aftab; Khaliq, Tasneem; Zahir, Zahir Ahmad

2017-04-01

reducing irrigation from I 300 to I 240 mm during 2012-2013 and 2013-2014 did not reduce crop yield significantly (P nitrogen application ranged from 31.2 to 55.4% at N 180 and N 240 kg ha -1 for different levels of irrigation. It is concluded from study that irrigation and nitrogen relationship can be used for efficient management of irrigation and nitrogen and to reduce nitrogen losses. The empirical equations developed in this study can help farmers of semi-arid environment to calculate optimum level of irrigation and nitrogen for maximum economic return from wheat.

A semi-empirical approach to analyze the activities of cylindrical radioactive samples using gamma energies from 185 to 1764 keV.

Science.gov (United States)

Huy, Ngo Quang; Binh, Do Quang

2014-12-01

This work suggests a method for determining the activities of cylindrical radioactive samples. The self-attenuation factor was applied for providing the self-absorption correction of gamma rays in the sample material. The experimental measurement of a (238)U reference sample and the calculation using the MCNP5 code allow obtaining the semi-empirical formulae of detecting efficiencies for the gamma energies ranged from 185 to 1764keV. These formulae were used to determine the activities of the (238)U, (226)Ra, (232)Th, (137)Cs and (40)K nuclides in the IAEA RGU-1, IAEA-434, IAEA RGTh-1, IAEA-152 and IAEA RGK-1 radioactive standards. The coincidence summing corrections for gamma rays in the (238)U and (232)Th series were applied. The activities obtained in this work were in good agreement with the reference values. Copyright © 2014 Elsevier Ltd. All rights reserved.

NARROW-LINE-WIDTH UV BURSTS IN THE TRANSITION REGION ABOVE SUNSPOTS OBSERVED BY IRIS

Energy Technology Data Exchange (ETDEWEB)

Hou, Zhenyong; Huang, Zhenghua; Xia, Lidong; Li, Bo; Madjarska, Maria S.; Fu, Hui; Mou, Chaozhou; Xie, Haixia, E-mail: z.huang@sdu.edu.cn, E-mail: xld@sdu.edu.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, 264209 Shandong (China)

2016-10-01

Various small-scale structures abound in the solar atmosphere above active regions, playing an important role in the dynamics and evolution therein. We report on a new class of small-scale transition region structures in active regions, characterized by strong emissions but extremely narrow Si iv line profiles as found in observations taken with the Interface Region Imaging Spectrograph (IRIS). Tentatively named as narrow-line-width UV bursts (NUBs), these structures are located above sunspots and comprise one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two data sets (a raster and a sit-and-stare data set). Among these, four events are short-lived with a duration of ∼10 minutes, while two last for more than 36 minutes. All NUBs have Doppler shifts of 15–18 km s{sup −1}, while the NUB found in sit-and-stare data possesses an additional component at ∼50 km s{sup −1} found only in the C ii and Mg ii lines. Given that these events are found to play a role in the local dynamics, it is important to further investigate the physical mechanisms that generate these phenomena and their role in the mass transport in sunspots.

Semi-empirical software for the aluminothermic and carbothermic reactions

Directory of Open Access Journals (Sweden)

Milorad Gavrilovski

2014-09-01

Full Text Available Understanding the reaction thermochemistry as well as formatting the empirical data about element distribution in gas-metal-slag phases is essential for creating a good model for aluminothermic and carbothermic reaction. In this paper modeling of material and energy balance of these reactions is described with the algorithm. The software, based on this model is basically made for production of high purity ferro alloys through aluminothermic process and then extended for some carbothermic process. Model validation is demonstrated with production of FeTi, FeW, FeB and FeMo in aluminothermic and reduction of mill scale, pyrite cinders and magnetite fines in carbothermic process.

Basis material decomposition in spectral CT using a semi-empirical, polychromatic adaption of the Beer-Lambert model

Science.gov (United States)

Ehn, S.; Sellerer, T.; Mechlem, K.; Fehringer, A.; Epple, M.; Herzen, J.; Pfeiffer, F.; Noël, P. B.

2017-01-01

Following the development of energy-sensitive photon-counting detectors using high-Z sensor materials, application of spectral x-ray imaging methods to clinical practice comes into reach. However, these detectors require extensive calibration efforts in order to perform spectral imaging tasks like basis material decomposition. In this paper, we report a novel approach to basis material decomposition that utilizes a semi-empirical estimator for the number of photons registered in distinct energy bins in the presence of beam-hardening effects which can be termed as a polychromatic Beer-Lambert model. A maximum-likelihood estimator is applied to the model in order to obtain estimates of the underlying sample composition. Using a Monte-Carlo simulation of a typical clinical CT acquisition, the performance of the proposed estimator was evaluated. The estimator is shown to be unbiased and efficient according to the Cramér-Rao lower bound. In particular, the estimator is capable of operating with a minimum number of calibration measurements. Good results were obtained after calibration using less than 10 samples of known composition in a two-material attenuation basis. This opens up the possibility for fast re-calibration in the clinical routine which is considered an advantage of the proposed method over other implementations reported in the literature.

Efficient dynamic graph construction for inductive semi-supervised learning.

Science.gov (United States)

Dornaika, F; Dahbi, R; Bosaghzadeh, A; Ruichek, Y

2017-10-01

Most of graph construction techniques assume a transductive setting in which the whole data collection is available at construction time. Addressing graph construction for inductive setting, in which data are coming sequentially, has received much less attention. For inductive settings, constructing the graph from scratch can be very time consuming. This paper introduces a generic framework that is able to make any graph construction method incremental. This framework yields an efficient and dynamic graph construction method that adds new samples (labeled or unlabeled) to a previously constructed graph. As a case study, we use the recently proposed Two Phase Weighted Regularized Least Square (TPWRLS) graph construction method. The paper has two main contributions. First, we use the TPWRLS coding scheme to represent new sample(s) with respect to an existing database. The representative coefficients are then used to update the graph affinity matrix. The proposed method not only appends the new samples to the graph but also updates the whole graph structure by discovering which nodes are affected by the introduction of new samples and by updating their edge weights. The second contribution of the article is the application of the proposed framework to the problem of graph-based label propagation using multiple observations for vision-based recognition tasks. Experiments on several image databases show that, without any significant loss in the accuracy of the final classification, the proposed dynamic graph construction is more efficient than the batch graph construction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Active semi-supervised learning method with hybrid deep belief networks.

Science.gov (United States)

Zhou, Shusen; Chen, Qingcai; Wang, Xiaolong

2014-01-01

In this paper, we develop a novel semi-supervised learning algorithm called active hybrid deep belief networks (AHD), to address the semi-supervised sentiment classification problem with deep learning. First, we construct the previous several hidden layers using restricted Boltzmann machines (RBM), which can reduce the dimension and abstract the information of the reviews quickly. Second, we construct the following hidden layers using convolutional restricted Boltzmann machines (CRBM), which can abstract the information of reviews effectively. Third, the constructed deep architecture is fine-tuned by gradient-descent based supervised learning with an exponential loss function. Finally, active learning method is combined based on the proposed deep architecture. We did several experiments on five sentiment classification datasets, and show that AHD is competitive with previous semi-supervised learning algorithm. Experiments are also conducted to verify the effectiveness of our proposed method with different number of labeled reviews and unlabeled reviews respectively.

Probability Estimates of Solar Proton Doses During Periods of Low Sunspot Number for Short Duration Missions

Science.gov (United States)

Atwell, William; Tylka, Allan J.; Dietrich, William F.; Rojdev, Kristina; Matzkind, Courtney

2016-01-01

In an earlier paper presented at ICES in 2015, we investigated solar particle event (SPE) radiation exposures (absorbed dose) to small, thinly-shielded spacecraft during a period when the monthly smoothed sunspot number (SSN) was less than 30. Although such months are generally considered "solar-quiet", SPEs observed during these months even include Ground Level Events, the most energetic type of SPE. In this paper, we add to previous study those SPEs that occurred in 1973-2015 when the SSN was greater than 30 but less than 50. Based on the observable energy range of the solar protons, we classify the event as GLEs, sub-GLEs, and sub-sub-GLEs, all of which are potential contributors to the radiation hazard. We use the spectra of these events to construct a probabilistic model of the absorbed dose due to solar protons when SSN < 50 at various confidence levels for various depths of shielding and for various mission durations. We provide plots and tables of solar proton-induced absorbed dose as functions of confidence level, shielding thickness, and mission-duration that will be useful to system designers.

A New Empirical Model for Radar Scattering from Bare Soil Surfaces

Directory of Open Access Journals (Sweden)

Nicolas Baghdadi

2016-11-01

Full Text Available The objective of this paper is to propose a new semi-empirical radar backscattering model for bare soil surfaces based on the Dubois model. A wide dataset of backscattering coefficients extracted from synthetic aperture radar (SAR images and in situ soil surface parameter measurements (moisture content and roughness is used. The retrieval of soil parameters from SAR images remains challenging because the available backscattering models have limited performances. Existing models, physical, semi-empirical, or empirical, do not allow for a reliable estimate of soil surface geophysical parameters for all surface conditions. The proposed model, developed in HH, HV, and VV polarizations, uses a formulation of radar signals based on physical principles that are validated in numerous studies. Never before has a backscattering model been built and validated on such an important dataset as the one proposed in this study. It contains a wide range of incidence angles (18°–57° and radar wavelengths (L, C, X, well distributed, geographically, for regions with different climate conditions (humid, semi-arid, and arid sites, and involving many SAR sensors. The results show that the new model shows a very good performance for different radar wavelengths (L, C, X, incidence angles, and polarizations (RMSE of about 2 dB. This model is easy to invert and could provide a way to improve the retrieval of soil parameters.

Solar magnetic field studies using the 12 micron emission lines. I - Quiet sun time series and sunspot slices

Science.gov (United States)

Deming, Drake; Boyle, Robert J.; Jennings, Donald E.; Wiedemann, Gunter

1988-01-01

The use of the extremely Zeeman-sensitive IR emission line Mg I, at 12.32 microns, to study solar magnetic fields. Time series observations of the line in the quiet sun were obtained in order to determine the response time of the line to the five-minute oscillations. Based upon the velocity amplitude and average period measured in the line, it is concluded that it is formed in the temperature minimum region. The magnetic structure of sunspots is investigated by stepping a small field of view in linear 'slices' through the spots. The region of penumbral line formation does not show the Evershed outflow common in photospheric lines. The line intensity is a factor of two greater in sunspot penumbrae than in the photosphere, and at the limb the penumbral emission begins to depart from optical thinness, the line source function increasing with height. For a spot near disk center, the radial decrease in absolute magnetic field strength is steeper than the generally accepted dependence.

Semi-Automatic Construction of Skeleton Concept Maps from Case Judgments

NARCIS (Netherlands)

Boer, A.; Sijtsma, B.; Winkels, R.; Lettieri, N.

2014-01-01

This paper proposes an approach to generating Skeleton Conceptual Maps (SCM) semi automatically from legal case documents provided by the United Kingdom’s Supreme Court. SCM are incomplete knowledge representations for the purpose of scaffolding learning. The proposed system intends to provide

TIME DISTRIBUTIONS OF LARGE AND SMALL SUNSPOT GROUPS OVER FOUR SOLAR CYCLES

International Nuclear Information System (INIS)

Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Cao, W.; Ozguc, A.; Rozelot, J. P.

2011-01-01

Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles 20-23 by using Rome (cycles 20 and 21) and Learmonth Solar Observatory (cycles 22 and 23) SG numbers. All SGs recorded during these time intervals were separated into two groups. The first group includes small SGs (A, B, C, H, and J classes by Zurich classification), and the second group consists of large SGs (D, E, F, and G classes). We then calculated small and large SG numbers from their daily mean numbers as observed on the solar disk during a given month. We report that the time variations of small and large SG numbers are asymmetric except for solar cycle 22. In general, large SG numbers appear to reach their maximum in the middle of the solar cycle (phases 0.45-0.5), while the international sunspot numbers and the small SG numbers generally peak much earlier (solar cycle phases 0.29-0.35). Moreover, the 10.7 cm solar radio flux, the facular area, and the maximum coronal mass ejection speed show better agreement with the large SG numbers than they do with the small SG numbers. Our results suggest that the large SG numbers are more likely to shed light on solar activity and its geophysical implications. Our findings may also influence our understanding of long-term variations of the total solar irradiance, which is thought to be an important factor in the Sun-Earth climate relationship.

THE MYSTERIOUS CASE OF THE SOLAR ARGON ABUNDANCE NEAR SUNSPOTS IN FLARES

International Nuclear Information System (INIS)

Doschek, G. A.; Warren, H. P.

2016-01-01

Recently we discussed an enhancement of the abundance of Ar xiv relative to Ca xiv near a sunspot during a flare, observed in spectra recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The observed Ar xiv/Ca xiv ratio yields an argon/calcium abundance ratio seven times greater than expected from the photospheric abundance. Such a large abundance anomaly is unprecedented in the solar atmosphere. We interpreted this result as being due to an inverse first ionization potential (FIP) effect. In the published work, two lines of Ar xiv were observed, and one line was tentatively identified as an Ar xi line. In this paper, we report observing a similar enhancement in a full-CCD EIS flare spectrum in 13 argon lines that lie within the EIS wavelength ranges. The observed lines include two Ar xi lines, four Ar xiii lines, six Ar xiv lines, and one Ar xv line. The enhancement is far less than reported in Doschek et al. but exhibits similar morphology. The argon abundance is close to a photospheric abundance in the enhanced area, and the abundance could be photospheric. This enhancement occurs in association with a sunspot in a small area only a few arcseconds (1″ = about 700 km) in size. There is no enhancement effect observed in the normally high-FIP sulfur and oxygen line ratios relative to lines of low-FIP elements available to EIS. Calculations of path lengths in the strongest enhanced area in Doschek et al. indicate a depletion of low-FIP elements.

Empirical likelihood

CERN Document Server

Owen, Art B

2001-01-01

Empirical likelihood provides inferences whose validity does not depend on specifying a parametric model for the data. Because it uses a likelihood, the method has certain inherent advantages over resampling methods: it uses the data to determine the shape of the confidence regions, and it makes it easy to combined data from multiple sources. It also facilitates incorporating side information, and it simplifies accounting for censored, truncated, or biased sampling.One of the first books published on the subject, Empirical Likelihood offers an in-depth treatment of this method for constructing confidence regions and testing hypotheses. The author applies empirical likelihood to a range of problems, from those as simple as setting a confidence region for a univariate mean under IID sampling, to problems defined through smooth functions of means, regression models, generalized linear models, estimating equations, or kernel smooths, and to sampling with non-identically distributed data. Abundant figures offer vi...

Empirical Analysis of Construction Safety Climate - A Study

OpenAIRE

S.V.S.RAJA PRASAD; K.P.REGHUNATH

2010-01-01

Safety in the construction industry has always been a major issue. Though much improvement in construction safety has been achieved, the industry still continues to lag behind most other industries with regard to safety. The safety climate of any organization consists of employee’s attitudes towards and perceptions of, health and safety behavior. Construction workers attitudes towards safety are influenced by their perceptions of risk, management, safety rulesand procedures. A measure of safe...

Denoising of chaotic signal using independent component analysis and empirical mode decomposition with circulate translating

Science.gov (United States)

Wen-Bo, Wang; Xiao-Dong, Zhang; Yuchan, Chang; Xiang-Li, Wang; Zhao, Wang; Xi, Chen; Lei, Zheng

2016-01-01

In this paper, a new method to reduce noises within chaotic signals based on ICA (independent component analysis) and EMD (empirical mode decomposition) is proposed. The basic idea is decomposing chaotic signals and constructing multidimensional input vectors, firstly, on the base of EMD and its translation invariance. Secondly, it makes the independent component analysis on the input vectors, which means that a self adapting denoising is carried out for the intrinsic mode functions (IMFs) of chaotic signals. Finally, all IMFs compose the new denoised chaotic signal. Experiments on the Lorenz chaotic signal composed of different Gaussian noises and the monthly observed chaotic sequence on sunspots were put into practice. The results proved that the method proposed in this paper is effective in denoising of chaotic signals. Moreover, it can correct the center point in the phase space effectively, which makes it approach the real track of the chaotic attractor. Project supported by the National Science and Technology, China (Grant No. 2012BAJ15B04), the National Natural Science Foundation of China (Grant Nos. 41071270 and 61473213), the Natural Science Foundation of Hubei Province, China (Grant No. 2015CFB424), the State Key Laboratory Foundation of Satellite Ocean Environment Dynamics, China (Grant No. SOED1405), the Hubei Provincial Key Laboratory Foundation of Metallurgical Industry Process System Science, China (Grant No. Z201303), and the Hubei Key Laboratory Foundation of Transportation Internet of Things, Wuhan University of Technology, China (Grant No.2015III015-B02).

Technology Management on Large Construction Projects

DEFF Research Database (Denmark)

Bonke, Sten

The aim of this text is to discuss and to develop the concept of technology management in relation to the empirical field of construction projects. In the first of the two main sections central theories and their derived assertions concerning technology management criteria are summed up...... Fixed Link construction project. Finally on this basis the concluding remarks are pointing to the main theoretical problems and their practical implementations for the introduction of a technology management discipline in construction....... in a schematic theoretical framework. Hereafter the general characteristics of construction are examined from the point of view of serving as an empirical field for technology management analysis. In the second section the technology management theme is associated with the empirical properties of the Great Belt...

Enhanced manifold regularization for semi-supervised classification.

Science.gov (United States)

Gan, Haitao; Luo, Zhizeng; Fan, Yingle; Sang, Nong

2016-06-01

Manifold regularization (MR) has become one of the most widely used approaches in the semi-supervised learning field. It has shown superiority by exploiting the local manifold structure of both labeled and unlabeled data. The manifold structure is modeled by constructing a Laplacian graph and then incorporated in learning through a smoothness regularization term. Hence the labels of labeled and unlabeled data vary smoothly along the geodesics on the manifold. However, MR has ignored the discriminative ability of the labeled and unlabeled data. To address the problem, we propose an enhanced MR framework for semi-supervised classification in which the local discriminative information of the labeled and unlabeled data is explicitly exploited. To make full use of labeled data, we firstly employ a semi-supervised clustering method to discover the underlying data space structure of the whole dataset. Then we construct a local discrimination graph to model the discriminative information of labeled and unlabeled data according to the discovered intrinsic structure. Therefore, the data points that may be from different clusters, though similar on the manifold, are enforced far away from each other. Finally, the discrimination graph is incorporated into the MR framework. In particular, we utilize semi-supervised fuzzy c-means and Laplacian regularized Kernel minimum squared error for semi-supervised clustering and classification, respectively. Experimental results on several benchmark datasets and face recognition demonstrate the effectiveness of our proposed method.

Developmant of a Reparametrized Semi-Empirical Force Field to Compute the Rovibrational Structure of Large PAHs

Science.gov (United States)

Fortenberry, Ryan

energy surface. QFFs can regularly predict the fundamental vibrational frequencies to within 5 cm-1 of experimentally measured values. This level of accuracy represents a reduction in discrepancies by an order of magnitude compared with harmonic frequencies calculated with density functional theory (DFT). The major limitation of the QFF strategy is that the level of electronic-structure theory required to develop a predictive force field is prohibitively time consuming for molecular systems larger than 5 atoms. Recent advances in QFF techniques utilizing informed DFT approaches have pushed the size of the systems studied up to 24 heavy atoms, but relevant PAHs can have up to hundreds of atoms. We have developed alternative electronic-structure methods that maintain the accuracy of the coupled-cluster calculations extrapolated to the complete basis set limit with relativistic and core correlation corrections applied: the CcCR QFF. These alternative methods are based on simplifications of Hartree—Fock theory in which the computationally intensive two-electron integrals are approximated using empirical parameters. These methods reduce computational time to orders of magnitude less than the CcCR calculations. We have derived a set of optimized empirical parameters to minimize the difference molecular ions of astrochemical significance. We have shown that it is possible to derive a set of empirical parameters that will produce RMS energy differences of less than 2 cm- 1 for our test systems. We are proposing to adopt this reparameterization strategy and some of the lessons learned from the informed DFT studies to create a semi-empirical method whose tremendous speed will allow us to study the rovibrational structure of large PAHs with up to 100s of carbon atoms.

An empirical model of L-band scintillation S4 index constructed by using FORMOSAT-3/COSMIC data

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Chen, Shih-Ping; Bilitza, Dieter; Liu, Jann-Yenq; Caton, Ronald; Chang, Loren C.; Yeh, Wen-Hao

2017-09-01

Modern society relies heavily on the Global Navigation Satellite System (GNSS) technology for applications such as satellite communication, navigation, and positioning on the ground and/or aviation in the troposphere/stratosphere. However, ionospheric scintillations can severely impact GNSS systems and their related applications. In this study, a global empirical ionospheric scintillation model is constructed with S4-index data obtained by the FORMOSAT-3/COSMIC (F3/C) satellites during 2007-2014 (hereafter referred to as the F3CGS4 model). This model describes the S4-index as a function of local time, day of year, dip-latitude, and solar activity using the index PF10.7. The model reproduces the F3/C S4-index observations well, and yields good agreement with ground-based reception of satellite signals. This confirms that the constructed model can be used to forecast global L-band scintillations on the ground and in the near surface atmosphere.

Fast and accurate semi-automated segmentation method of spinal cord MR images at 3T applied to the construction of a cervical spinal cord template.

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Mohamed-Mounir El Mendili

Full Text Available To design a fast and accurate semi-automated segmentation method for spinal cord 3T MR images and to construct a template of the cervical spinal cord.A semi-automated double threshold-based method (DTbM was proposed enabling both cross-sectional and volumetric measures from 3D T2-weighted turbo spin echo MR scans of the spinal cord at 3T. Eighty-two healthy subjects, 10 patients with amyotrophic lateral sclerosis, 10 with spinal muscular atrophy and 10 with spinal cord injuries were studied. DTbM was compared with active surface method (ASM, threshold-based method (TbM and manual outlining (ground truth. Accuracy of segmentations was scored visually by a radiologist in cervical and thoracic cord regions. Accuracy was also quantified at the cervical and thoracic levels as well as at C2 vertebral level. To construct a cervical template from healthy subjects' images (n=59, a standardization pipeline was designed leading to well-centered straight spinal cord images and accurate probability tissue map.Visual scoring showed better performance for DTbM than for ASM. Mean Dice similarity coefficient (DSC was 95.71% for DTbM and 90.78% for ASM at the cervical level and 94.27% for DTbM and 89.93% for ASM at the thoracic level. Finally, at C2 vertebral level, mean DSC was 97.98% for DTbM compared with 98.02% for TbM and 96.76% for ASM. DTbM showed similar accuracy compared with TbM, but with the advantage of limited manual interaction.A semi-automated segmentation method with limited manual intervention was introduced and validated on 3T images, enabling the construction of a cervical spinal cord template.

Fast and accurate semi-automated segmentation method of spinal cord MR images at 3T applied to the construction of a cervical spinal cord template.

Science.gov (United States)

El Mendili, Mohamed-Mounir; Chen, Raphaël; Tiret, Brice; Villard, Noémie; Trunet, Stéphanie; Pélégrini-Issac, Mélanie; Lehéricy, Stéphane; Pradat, Pierre-François; Benali, Habib

2015-01-01

To design a fast and accurate semi-automated segmentation method for spinal cord 3T MR images and to construct a template of the cervical spinal cord. A semi-automated double threshold-based method (DTbM) was proposed enabling both cross-sectional and volumetric measures from 3D T2-weighted turbo spin echo MR scans of the spinal cord at 3T. Eighty-two healthy subjects, 10 patients with amyotrophic lateral sclerosis, 10 with spinal muscular atrophy and 10 with spinal cord injuries were studied. DTbM was compared with active surface method (ASM), threshold-based method (TbM) and manual outlining (ground truth). Accuracy of segmentations was scored visually by a radiologist in cervical and thoracic cord regions. Accuracy was also quantified at the cervical and thoracic levels as well as at C2 vertebral level. To construct a cervical template from healthy subjects' images (n=59), a standardization pipeline was designed leading to well-centered straight spinal cord images and accurate probability tissue map. Visual scoring showed better performance for DTbM than for ASM. Mean Dice similarity coefficient (DSC) was 95.71% for DTbM and 90.78% for ASM at the cervical level and 94.27% for DTbM and 89.93% for ASM at the thoracic level. Finally, at C2 vertebral level, mean DSC was 97.98% for DTbM compared with 98.02% for TbM and 96.76% for ASM. DTbM showed similar accuracy compared with TbM, but with the advantage of limited manual interaction. A semi-automated segmentation method with limited manual intervention was introduced and validated on 3T images, enabling the construction of a cervical spinal cord template.

A semi-empirical model for the formation and depletion of the high burnup structure in UO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Pizzocri, D. [European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, PO Box 2340, 76125, Karlsruhe (Germany); Politecnico di Milano, Department of Energy, Nuclear Engineering Division, Via La Masa 34, 20156, Milan (Italy); Cappia, F. [European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, PO Box 2340, 76125, Karlsruhe (Germany); Technische Universität München, Boltzmannstraße 15, 85747, Garching bei München (Germany); Luzzi, L., E-mail: lelio.luzzi@polimi.it [Politecnico di Milano, Department of Energy, Nuclear Engineering Division, Via La Masa 34, 20156, Milan (Italy); Pastore, G. [Idaho National Laboratory, Fuel Modeling and Simulation Department, 2525 Fremont Avenue, 83415, Idaho Falls (United States); Rondinella, V.V.; Van Uffelen, P. [European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, PO Box 2340, 76125, Karlsruhe (Germany)

2017-04-15

In the rim zone of UO{sub 2} nuclear fuel pellets, the combination of high burnup and low temperature drives a microstructural change, leading to the formation of the high burnup structure (HBS). In this work, we propose a semi-empirical model to describe the formation of the HBS, which embraces the polygonisation/recrystallization process and the depletion of intra-granular fission gas, describing them as inherently related. For this purpose, we performed grain-size measurements on samples at radial positions in which the restructuring was incomplete. Based on these new experimental data, we infer an exponential reduction of the average grain size with local effective burnup, paired with a simultaneous depletion of intra-granular fission gas driven by diffusion. The comparison with currently used models indicates the applicability of the herein developed model within integral fuel performance codes. - Highlights: •Development of a new model for the formation and depletion of the high burnup structure. •New average grain-size measurements to support model development. •Formation threshold of the high burnup structure based on the concept of effective burnup. •Coupled description of grain recrystallization/polygonisation and depletion of intra-granular fission gas. •Model suitable for application in fuel performance codes.

Molecular models of zinc phthalocyanines: semi-empirical molecular orbital computations and physicochemical properties studied by molecular mechanics simulations

International Nuclear Information System (INIS)

Gantchev, Tsvetan G.; van Lier, Johan E.; Hunting, Darel J.

2005-01-01

To build 3D-molecular models of Zinc-phthalocyanines (ZnPc) and to study their diverse chemical and photosensitization properties, we performed quantum mechanical molecular orbital (MO) semi-empirical (AM1) computations of the ground, excited singlet and triplet states as well as free radical (ionic) species. RHF and UHF (open shell) geometry optimizations led to near-perfect symmetrical ZnPc. Predicted ionization potentials (IP), electron affinities (EA) and lowest electronic transitions of ZnPc are in good agreement with the published experimental and theoretical data. The computation-derived D 4h /D 2h -symmetry 3D-structures of ground and excited states and free radicals of ZnPc, together with the frontier orbital energies and Mulliken electron population analysis enabled us to build robust molecular models. These models were used to predict important chemical-reactivity entities such as global electronegativity (χ), hardness (η) and local softness based on Fukui-functions analysis. Examples of molecular mechanics (MM) applications of the 3D-molecular models are presented as approaches to evaluate solvation free energy (ΔG 0 ) solv and to estimate ground- and excited- state oxidation/reduction potentials as well as intermolecular interactions and stability of ground and excited state dimers (exciplexes) and radical ion-pairs

Investigation of naproxen drug using mass spectrometry, thermal analyses and semi-empirical molecular orbital calculation

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M.A. Zayed

2017-03-01

Full Text Available Naproxen (C14H14O3 is a non-steroidal anti-inflammatory drug (NSAID. It is important to investigate its structure to know the active groups and weak bonds responsible for medical activity. In the present study, naproxen was investigated by mass spectrometry (MS, thermal analysis (TA measurements (TG/DTG and DTA and confirmed by semi empirical molecular orbital (MO calculation, using PM3 procedure. These calculations included, bond length, bond order, bond strain, partial charge distribution, ionization energy and heat of formation (ΔHf. The mass spectra and thermal analysis fragmentation pathways were proposed and compared to select the most suitable scheme representing the correct fragmentation pathway of the drug in both techniques. The PM3 procedure reveals that the primary cleavage site of the charged molecule is the rupture of the COOH group (lowest bond order and high strain which followed by CH3 loss of the methoxy group. Thermal analysis of the neutral drug reveals a high response to the temperature variation with very fast rate. It decomposed in several sequential steps in the temperature range 80–400 °C. These mass losses appear as two endothermic and one exothermic peaks which required energy values of 255.42, 10.67 and 371.49 J g−1 respectively. The initial thermal ruptures are similar to that obtained by mass spectral fragmentation (COOH rupture. It was followed by the loss of the methyl group and finally by ethylene loss. Therefore, comparison between MS and TA helps in selection of the proper pathway representing its fragmentation. This comparison is successfully confirmed by MO-calculation.

Oscillations in sunspot umbras due to trapped Alfven waves excited by overstability

International Nuclear Information System (INIS)

Uchida, Yutaka; Sakurai, Takashi.

1975-01-01

Oscillations observed in sunspot umbras are interpreted as a vertical motion in the atmosphere induced by a standing Alfven wave trapped in the region between the overstable layer under the photosphere and the chromosphere-corona transition layer. The Alfven wave motion is considered to be excited by the overstable convection occurring at the bottom of the abovementioned oscillating layer, and waves with special frequencies are selected as eigen-mode waves standing in the ''cavity,'' while other waves which are out of phase with themselves after reflections will disappear. It is shown by solving the eigen-value problem that the fundamental eigen frequency falls in a range around 0.04 rad s -1 (corresponding to 140-180 s) for the condition in the umbra of a typical spot, and also that the eigen frequencies do not depend greatly on the circumstantial physical or geometric parameters of the model atmosphere, such as the temperature in the layer, or the height of the transition layer, etc. The eigen frequencies, however, depend on the Alfven velocity at the base of the oscillating layer (or at the top of the overstable layer), but the latter quantity, which represents the stiffness of the magnetic tube of force against the overturning motion, takes roughly a common value for different sunspots according to SAVAGE's (1969) stability analysis of the umbral atmosphere against thermal convection, and thus gives a comparatively narrow range of resonant frequencies. In addition to the selection mechanism for oscillations of 140-180-s period, some other aspects of the oscillation, such as the relation to the running penumbral waves, are discussed. (auth.)

Role of Construction Sector in Economic Growth: Empirical ...

African Journals Online (AJOL)

FUTY Journal of the Environment ... The construction industry plays an important role in the economy, and the activities of the industry are also vital to the achievement of national socio-economic development goals of providing shelter, ... investigate the relationship between the construction sector and aggregate economy.

Modeling ionospheric foF2 by using empirical orthogonal function analysis

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E. A

2011-08-01

Full Text Available A similar-parameters interpolation method and an empirical orthogonal function analysis are used to construct empirical models for the ionospheric foF2 by using the observational data from three ground-based ionosonde stations in Japan which are Wakkanai (Geographic 45.4° N, 141.7° E, Kokubunji (Geographic 35.7° N, 140.1° E and Yamagawa (Geographic 31.2° N, 130.6° E during the years of 1971–1987. The impact of different drivers towards ionospheric foF2 can be well indicated by choosing appropriate proxies. It is shown that the missing data of original foF2 can be optimal refilled using similar-parameters method. The characteristics of base functions and associated coefficients of EOF model are analyzed. The diurnal variation of base functions can reflect the essential nature of ionospheric foF2 while the coefficients represent the long-term alteration tendency. The 1st order EOF coefficient A1 can reflect the feature of the components with solar cycle variation. A1 also contains an evident semi-annual variation component as well as a relatively weak annual fluctuation component. Both of which are not so obvious as the solar cycle variation. The 2nd order coefficient A2 contains mainly annual variation components. The 3rd order coefficient A3 and 4th order coefficient A4 contain both annual and semi-annual variation components. The seasonal variation, solar rotation oscillation and the small-scale irregularities are also included in the 4th order coefficient A4. The amplitude range and developing tendency of all these coefficients depend on the level of solar activity and geomagnetic activity. The reliability and validity of EOF model are verified by comparison with observational data and with International Reference Ionosphere (IRI. The agreement between observations and EOF model is quite well, indicating that the EOF model can reflect the major changes and the temporal distribution characteristics of the mid-latitude ionosphere of the

Critical frequencies of the ionospheric F1 and F2 layers during the last four solar cycles: Sunspot group type dependencies

Science.gov (United States)

Yiǧit, Erdal; Kilcik, Ali; Elias, Ana Georgina; Dönmez, Burçin; Ozguc, Atila; Yurchshyn, Vasyl; Rozelot, Jean-Pierre

2018-06-01

The long term solar activity dependencies of ionospheric F1 and F2 regions' critical frequencies (f0F1 and f0F2) are analyzed for the last four solar cycles (1976-2015). We show that the ionospheric F1 and F2 regions have different solar activity dependencies in terms of the sunspot group (SG) numbers: F1 region critical frequency (f0F1) peaks at the same time with the small SG numbers, while the f0F2 reaches its maximum at the same time with the large SG numbers, especially during the solar cycle 23. The observed differences in the sensitivity of ionospheric critical frequencies to sunspot group (SG) numbers provide a new insight into the solar activity effects on the ionosphere and space weather. While the F1 layer is influenced by the slow solar wind, which is largely associated with small SGs, the ionospheric F2 layer is more sensitive to Coronal Mass Ejections (CMEs) and fast solar winds, which are mainly produced by large SGs and coronal holes. The SG numbers maximize during of peak of the solar cycle and the number of coronal holes peaks during the sunspot declining phase. During solar minimum there are relatively less large SGs, hence reduced CME and flare activity. These results provide a new perspective for assessing how the different regions of the ionosphere respond to space weather effects.

A Family of Integrable Rational Semi-Discrete Systems and Its Reduction

International Nuclear Information System (INIS)

Xu Xixiang

2010-01-01

Within framework of zero curvature representation theory, a family of integrahle rational semi-discrete systems is derived from a matrix spectral problem. The Hamiltonian forms of obtained semi-discrete systems are constructed by means of the discrete trace identity. The Liouville integrability for the obtained family is demonstrated. In the end, a reduced family of obtained semi-discrete systems and its Hamiltonian form are worked out. (general)

Semi-infinite Weil complex and the Virasoro algebra

International Nuclear Information System (INIS)

Feigin, B.; Frenkel, E.

1991-01-01

We define a semi-infinite analogue of the Weil algebra associated with an infinite-dimensional Lie algebra. It can be used for the definition of semi-infinite characteristic classes by analogy with the Chern-Weil construction. The second term of a spectral sequence of this Weil complex consists of the semi-infinite cohomology of the Lie algebra with coefficients in its 'adjoint semi-infinite symmetric powers'. We compute this cohomology for the Virasoro algebra. This is just the BRST cohomology of the bosonic βγ-system with the central charge 26. We give a complete description of the Fock representations of this bosonic system as modules over the Virasoro algebra, using Friedan-Martinec-Shenker bosonization. We derive a combinatorial identity from this result. (orig.)

Semi-supervised and unsupervised extreme learning machines.

Science.gov (United States)

Huang, Gao; Song, Shiji; Gupta, Jatinder N D; Wu, Cheng

2014-12-01

Extreme learning machines (ELMs) have proven to be efficient and effective learning mechanisms for pattern classification and regression. However, ELMs are primarily applied to supervised learning problems. Only a few existing research papers have used ELMs to explore unlabeled data. In this paper, we extend ELMs for both semi-supervised and unsupervised tasks based on the manifold regularization, thus greatly expanding the applicability of ELMs. The key advantages of the proposed algorithms are as follows: 1) both the semi-supervised ELM (SS-ELM) and the unsupervised ELM (US-ELM) exhibit learning capability and computational efficiency of ELMs; 2) both algorithms naturally handle multiclass classification or multicluster clustering; and 3) both algorithms are inductive and can handle unseen data at test time directly. Moreover, it is shown in this paper that all the supervised, semi-supervised, and unsupervised ELMs can actually be put into a unified framework. This provides new perspectives for understanding the mechanism of random feature mapping, which is the key concept in ELM theory. Empirical study on a wide range of data sets demonstrates that the proposed algorithms are competitive with the state-of-the-art semi-supervised or unsupervised learning algorithms in terms of accuracy and efficiency.

An introduction to niche construction theory.

Science.gov (United States)

Laland, Kevin; Matthews, Blake; Feldman, Marcus W

Niche construction refers to the modification of selective environments by organisms. Theoretical and empirical studies of niche construction are increasing in importance as foci in evolutionary ecology. This special edition presents theoretical and empirical research that illustrates the significance of niche construction to the field. Here we set the scene for the following papers by (1) discussing the history of niche construction research, (2) providing clear definitions that distinguish niche construction from related concepts such as ecosystem engineering and the extended phenotype, (3) providing a brief summary of the findings of niche construction research, (4) discussing the contribution of niche construction and ecological inheritance to (a) expanded notions of inheritance, and (b) the extended evolutionary synthesis, and (5) briefly touching on some of the issues that underlie the controversies over niche construction.

Who supported the Deutsche Bundesbank? An empirical investigation

NARCIS (Netherlands)

Maier, P; Knaap, T

2002-01-01

The relevance of public support for monetary policy has largely been over-looked in the empirical Central Bank literature. We have constructed a new indicator for the support of the German Bundesbank and present descriptive and empirical evidence. We find that major German interest groups were quite

Solar wind and coronal structure near sunspot minimum: Pioneer and SMM observations from 1985-1987

International Nuclear Information System (INIS)

Mihalov, J.D.; Barnes, A.; Hundhausen, A.J.; Smith, E.J.

1990-01-01

The solar wind speeds observed in the outer heliosphere (20 to 40 AU heliocentric distance, approximately) by Pioneers 10 an 11, and at a heliocentric distance of 0.7 AU by the Pioneer Venus spacecraft, reveal a complex set of changes in the years near the recent sunspot minimum, 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations made from the Solar Maximum Mission spacecraft during the same epoch show a systematic variation in coronal structure and (by implication) the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet (or with heliomagnetic latitude), and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum. The authors confirm here that this basic organization of the solar wind speed persists in the outer heliosphere with an orientation of the neutral sheet consistent with that inferred at a heliocentric distance of a few solar radii, from the coronal observations

Discriminative semi-supervised feature selection via manifold regularization.

Science.gov (United States)

Xu, Zenglin; King, Irwin; Lyu, Michael Rung-Tsong; Jin, Rong

2010-07-01

Feature selection has attracted a huge amount of interest in both research and application communities of data mining. We consider the problem of semi-supervised feature selection, where we are given a small amount of labeled examples and a large amount of unlabeled examples. Since a small number of labeled samples are usually insufficient for identifying the relevant features, the critical problem arising from semi-supervised feature selection is how to take advantage of the information underneath the unlabeled data. To address this problem, we propose a novel discriminative semi-supervised feature selection method based on the idea of manifold regularization. The proposed approach selects features through maximizing the classification margin between different classes and simultaneously exploiting the geometry of the probability distribution that generates both labeled and unlabeled data. In comparison with previous semi-supervised feature selection algorithms, our proposed semi-supervised feature selection method is an embedded feature selection method and is able to find more discriminative features. We formulate the proposed feature selection method into a convex-concave optimization problem, where the saddle point corresponds to the optimal solution. To find the optimal solution, the level method, a fairly recent optimization method, is employed. We also present a theoretic proof of the convergence rate for the application of the level method to our problem. Empirical evaluation on several benchmark data sets demonstrates the effectiveness of the proposed semi-supervised feature selection method.

A Simple Semi-Empirical Model for the Estimation of Photosynthetically Active Radiation from Satellite Data in the Tropics

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S. Janjai

2013-01-01

Full Text Available This paper presents a simple semi-empirical model for estimating global photosynthetically active radiation (PAR under all sky conditions. The model expresses PAR as a function of cloud index, aerosol optical depth, total ozone column, solar zenith angle, and air mass. The formulation of the model was based on a four-year period (2008–2011 of PAR data obtained from the measurements at four solar monitoring stations in a tropical environment of Thailand. These are Chiang Mai (18.78°N, 98.98°E, Ubon Ratchathani (15.25°N, 104.87°E, Nakhon Pathom (13.82°N, 100.04°E, and Songkhla (7.20°N, 100.60°E. The cloud index was derived from MTSAT-1R satellite, whereas the aerosol optical depth was obtained from MODIS/Terra satellite. For the total ozone column, it was retrieved from OMI/Aura satellite. The model was validated against independent data set from the four stations. It was found that hourly PAR estimated from the proposed model and that obtained from the measurements were in reasonable agreement, with the root mean square difference (RMSD and mean bias difference (MBD of 14.3% and −5.8%, respectively. In addition, for the case of monthly average hourly PAR, RMSD and MBD were reduced to 11.1% and −5.1%, respectively.

The Role of Empirical Research in Bioethics

Science.gov (United States)

Kon, Alexander A.

2010-01-01

There has long been tension between bioethicists whose work focuses on classical philosophical inquiry and those who perform empirical studies on bioethical issues. While many have argued that empirical research merely illuminates current practices and cannot inform normative ethics, others assert that research-based work has significant implications for refining our ethical norms. In this essay, I present a novel construct for classifying empirical research in bioethics into four hierarchical categories: Lay of the Land, Ideal Versus Reality, Improving Care, and Changing Ethical Norms. Through explaining these four categories and providing examples of publications in each stratum, I define how empirical research informs normative ethics. I conclude by demonstrating how philosophical inquiry and empirical research can work cooperatively to further normative ethics. PMID:19998120

A semi-empirical model for mesospheric and stratospheric NOy produced by energetic particle precipitation

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B. Funke

2016-07-01

Full Text Available The MIPAS Fourier transform spectrometer on board Envisat has measured global distributions of the six principal reactive nitrogen (NOy compounds (HNO3, NO2, NO, N2O5, ClONO2, and HNO4 during 2002–2012. These observations were used previously to detect regular polar winter descent of reactive nitrogen produced by energetic particle precipitation (EPP down to the lower stratosphere, often called the EPP indirect effect. It has further been shown that the observed fraction of NOy produced by EPP (EPP-NOy has a nearly linear relationship with the geomagnetic Ap index when taking into account the time lag introduced by transport. Here we exploit these results in a semi-empirical model for computation of EPP-modulated NOy densities and wintertime downward fluxes through stratospheric and mesospheric pressure levels. Since the Ap dependence of EPP-NOy is distorted during episodes of strong descent in Arctic winters associated with elevated stratopause events, a specific parameterization has been developed for these episodes. This model accurately reproduces the observations from MIPAS and is also consistent with estimates from other satellite instruments. Since stratospheric EPP-NOy depositions lead to changes in stratospheric ozone with possible implications for climate, the model presented here can be utilized in climate simulations without the need to incorporate many thermospheric and upper mesospheric processes. By employing historical geomagnetic indices, the model also allows for reconstruction of the EPP indirect effect since 1850. We found secular variations of solar cycle-averaged stratospheric EPP-NOy depositions on the order of 1 GM. In particular, we model a reduction of the EPP-NOy deposition rate during the last 3 decades, related to the coincident decline of geomagnetic activity that corresponds to 1.8 % of the NOy production rate by N2O oxidation. As the decline of the geomagnetic activity level is expected to continue in the

Mesh construction and evaluation of the stress intensity factor for the semi-elliptical surface cracks

International Nuclear Information System (INIS)

Kim, Jong Wook; Lee, Gyu Mahn; Jeong, Kyeong Hoon; Kim, Tae Wan; Park, Keun Bae

2001-01-01

As actual cracks found in practical structures are mostly three-dimensional surface cracks, such cracks give rise to the important problem when the structural integrity is evaluated in a viewpoint of fracture mechanics. The case of a semi-elliptical surface crack is more complicated than that of the embedded elliptical crack since the crack front intersects the free surface. Therefore, the exact expression of stress field according to the boundary condition can be the prior process for the structural integrity evaluation . The commercial code, I-DEAS does not provide the family of strain singular element for the cracked-body analysis. This means that the user cannot make use of the pre-processing function of I-DEAS effectively. But I-DEAS has the capability to hold input data in common with computational fracture mechanics program like ABAQUS. Hence, user can construct the optimized analysis method for the generation of input data of program like ABAQUS using the I-DEAS. In the present study, a procedure for the generation of input data for the optimized 3-dimensional computational fracture mechanics is developed as a series of effort to establish the structural integriyt evaluation procedure of SMART reactor vessel assembly. Input data for the finite element analysis are made using the commercial code, I-DEAS program, The stress analysis is performed using the ABAQUS. To demonstrate the validation of the developed procedure in the present sutdy, semi-elliptic surface crack in a half space subjected to uniform tension are solved, and the effects of crack configuration ratio are discussed in detail. The numerical results are presented and compared to those presented by Raju and Newman. Also, we have established the structural integrity evaluation procedure through the 3-D crack modeling

Robust Semi-Supervised Manifold Learning Algorithm for Classification

Directory of Open Access Journals (Sweden)

Mingxia Chen

2018-01-01

Full Text Available In the recent years, manifold learning methods have been widely used in data classification to tackle the curse of dimensionality problem, since they can discover the potential intrinsic low-dimensional structures of the high-dimensional data. Given partially labeled data, the semi-supervised manifold learning algorithms are proposed to predict the labels of the unlabeled points, taking into account label information. However, these semi-supervised manifold learning algorithms are not robust against noisy points, especially when the labeled data contain noise. In this paper, we propose a framework for robust semi-supervised manifold learning (RSSML to address this problem. The noisy levels of the labeled points are firstly predicted, and then a regularization term is constructed to reduce the impact of labeled points containing noise. A new robust semi-supervised optimization model is proposed by adding the regularization term to the traditional semi-supervised optimization model. Numerical experiments are given to show the improvement and efficiency of RSSML on noisy data sets.

Normal and counter Evershed flows in the photospheric penumbra of a sunspot SPINOR 2D inversions of Hinode-SOT/SP observations

Czech Academy of Sciences Publication Activity Database

Siu-Tapia, A.; Lagg, A.; Solanki, S.K.; van Noort, M.; Jurčák, Jan

2017-01-01

Roč. 607, November (2017), A36/1-A36/17 E-ISSN 1432-0746 Institutional support: RVO:67985815 Keywords : sunspots * photosphere * magnetic fields Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.014, year: 2016

Comparison of ITER performance predicted by semi-empirical and theory-based transport models

International Nuclear Information System (INIS)

Mukhovatov, V.; Shimomura, Y.; Polevoi, A.

2003-01-01

The values of Q=(fusion power)/(auxiliary heating power) predicted for ITER by three different methods, i.e., transport model based on empirical confinement scaling, dimensionless scaling technique, and theory-based transport models are compared. The energy confinement time given by the ITERH-98(y,2) scaling for an inductive scenario with plasma current of 15 MA and plasma density 15% below the Greenwald value is 3.6 s with one technical standard deviation of ±14%. These data are translated into a Q interval of [7-13] at the auxiliary heating power P aux = 40 MW and [7-28] at the minimum heating power satisfying a good confinement ELMy H-mode. Predictions of dimensionless scalings and theory-based transport models such as Weiland, MMM and IFS/PPPL overlap with the empirical scaling predictions within the margins of uncertainty. (author)

Theoretical Research Progress in High-Velocity/Hypervelocity Impact on Semi-Infinite Targets

Directory of Open Access Journals (Sweden)

Yunhou Sun

2015-01-01

Full Text Available With the hypervelocity kinetic weapon and hypersonic cruise missiles research projects being carried out, the damage mechanism for high-velocity/hypervelocity projectile impact on semi-infinite targets has become the research keystone in impact dynamics. Theoretical research progress in high-velocity/hypervelocity impact on semi-infinite targets was reviewed in this paper. The evaluation methods for critical velocity of high-velocity and hypervelocity impact were summarized. The crater shape, crater scaling laws and empirical formulae, and simplified analysis models of crater parameters for spherical projectiles impact on semi-infinite targets were reviewed, so were the long rod penetration state differentiation, penetration depth calculation models for the semifluid, and deformed long rod projectiles. Finally, some research proposals were given for further study.

Semi-Automatic Construction of Skeleton Concept Maps from Case Judgments

OpenAIRE

Boer, A.; Sijtsma, B.; Winkels, R.; Lettieri, N.

2014-01-01

This paper proposes an approach to generating Skeleton Conceptual Maps (SCM) semi automatically from legal case documents provided by the United Kingdom’s Supreme Court. SCM are incomplete knowledge representations for the purpose of scaffolding learning. The proposed system intends to provide students with a tool to pre-process text and to extract knowledge from documents in a time saving manner. A combination of natural language processing methods and proposition extraction algorithms are u...

COUNTERBALANCING BENEFITS AND DRAWBACKS OF CONTEMPORARY STABLISED EARTH CONSTRUCTION BY CONSTRUCTION PROFESSIONALS

Directory of Open Access Journals (Sweden)

Mohammad Sharif Zami

2011-07-01

Full Text Available It is debatable among the construction professionals whether contemporary stabilised earth construction is beneficial in urban low cost housing. Existing literature recorded a lot of benefits and drawbacks from construction professionals, which is empirically substantiated. But there are drawbacks found in the literature that seemingly are conflicting, and construction professionals are divided in their opinion. This paper seeks to address these conflicts and division by validating the controversial drawbacks of contemporary stabilised earth construction in urban low cost housing.

Multiple gamma lines from semi-annihilation

International Nuclear Information System (INIS)

D'Eramo, Francesco; McCullough, Matthew; Thaler, Jesse

2013-01-01

Hints in the Fermi data for a 130 GeV gamma line from the galactic center have ignited interest in potential gamma line signatures of dark matter. Explanations of this line based on dark matter annihilation face a parametric tension since they often rely on large enhancements of loop-suppressed cross sections. In this paper, we pursue an alternative possibility that dark matter gamma lines could arise from ''semi-annihilation'' among multiple dark sector states. The semi-annihilation reaction ψ i ψ j → ψ k γ with a single final state photon is typically enhanced relative to ordinary annihilation ψ i ψ-bar i → γγ into photon pairs. Semi-annihilation allows for a wide range of dark matter masses compared to the fixed mass value required by annihilation, opening the possibility to explain potential dark matter signatures at higher energies. The most striking prediction of semi-annihilation is the presence of multiple gamma lines, with as many as order N 3 lines possible for N dark sector states, allowing for dark sector spectroscopy. A smoking gun signature arises in the simplest case of degenerate dark matter, where a strong semi-annihilation line at 130 GeV would be accompanied by a weaker annihilation line at 173 GeV. As a proof of principle, we construct two explicit models of dark matter semi-annihilation, one based on non-Abelian vector dark matter and the other based on retrofitting Rayleigh dark matter

Performance of Chickens under Semi-scavenging Conditions: A ...

African Journals Online (AJOL)

Performance of Chickens under Semi-scavenging Conditions: A Case Study of ... per household was lost per year due to diseases, predators, accidents, and theft. ... as well as chicken house construction so as to avoid the risks of predators.

Semi-empirical correlation for binary interaction parameters of the Peng-Robinson equation of state with the van der Waals mixing rules for the prediction of high-pressure vapor-liquid equilibrium.

Science.gov (United States)

Fateen, Seif-Eddeen K; Khalil, Menna M; Elnabawy, Ahmed O

2013-03-01

Peng-Robinson equation of state is widely used with the classical van der Waals mixing rules to predict vapor liquid equilibria for systems containing hydrocarbons and related compounds. This model requires good values of the binary interaction parameter kij . In this work, we developed a semi-empirical correlation for kij partly based on the Huron-Vidal mixing rules. We obtained values for the adjustable parameters of the developed formula for over 60 binary systems and over 10 categories of components. The predictions of the new equation system were slightly better than the constant-kij model in most cases, except for 10 systems whose predictions were considerably improved with the new correlation.

On the Theory of Sunspots Proposed by Signor Kirchoff

Directory of Open Access Journals (Sweden)

Secchi A.

2011-07-01

Full Text Available Eileen Reeves (Department of Comparative Literature, Princeton University, Princeton, New Jersey, 08544 and Mary Posani (Department of French and Italian, The Ohio State University, Columbus, Ohio, 43221 provide a translation of Father Pietro Angelo Secchi’s classic work “ Secchi A. Sulla Teoria Delle Macchie Solari: Proposta dal sig. Kirchoff” as it appeared in Bullettino Meteorologico dell’ Osservatorio del Collegio Romano , 31 January 1864, v.3(4, 1–4. This was the first treatise to propose a partic- ulate photosphere floating on the gaseous body of the Sun. The idea would dominate astrophysical thought for the next 50 years. Secchi appears to have drafted the article, as a response to Gustav Kirchhoff’s proposal, echoing early Galilean ideas, that sunspots represented clouds which floated above the photosphere. Other than presenting a new solar model, noteworthy aspects of this work include Secchi’s appropriate insistence that materials do not emit the same light at the same temperature and his gentle rebuke of Kirchhoff relative to commenting on questions of astronomy.

[Research on the hospital construction and structure in Daehan empire and colonial modern period].

Science.gov (United States)

Han, Dong Gwan; Ryu, Chang Ug; Ko, Sang Kyun; Jung, Jae Kook; Moon, Jong Youn; Park, Yoon Hyung

2011-12-31

It was the late Chosun Dynasty and Daehan Empire era that Western Medicine has firstly been introduced to Korea, previously operating on a basis of Korean traditional medicine. Western Medicine has been introduced by American missionary and Japanese Imperialism. An introduction of Western Medicine made it feasible to proceed new type medical care including operation, leading to require a new form of medical facilities. In the beginning, new facilities were constructed by Japanese Imperialism. Other hand many of facilities including Severance Hospital were established by missionaries. First of all, Daehan Empire established and managed a modern type of medical facility named "Jejoongwon" in 1885 as a government institution hospital. The Red Cross Hospital built in 1889. Afterwards, Jejoongwon and the Red Cross Hospital were taken over to missionary hospital and Japanese Imperialism, respectively. Japanese Imperialists firstly have protected their nationals residing in Chosun but have proceeded care a few Chosun people to exploit medical treatment as a mean to advertise superiority of the Empire of Japan. The facility that has firstly been established and managed was Jeseang Hospital in Busan in 1877, leading to establish in Wonju, Wonsan, and Mokpo. Afterwards, Japan has organized "Donginhoi" as a civil invasion organization, leading for "Donginhoi" to established "Dongin Hospital" in Pyeongyang, Daegu, and Seoul. Since 1909, governmental leading medical facility named Jahye Hospital was established according to an imperial order, leading to establish 32 hospitals all over the nation. American missionaries have established and managed 28 hospitals started from Severance Hospital built in 1904. However, Chosun doctors started to having educated and opening up their own hospital since 1920, leading for many of medical facilities to be established, but most of them have taken different roles followed by 6.25 War and economic development period. However, some of them

Empirical Data and Results of the Construct Vadility Studies

NARCIS (Netherlands)

Ravaja, N.; de Kort, Y.A.W.; IJsselsteijn, W.A.; Klimmt, C.; Lindley, C.; Mathiak, K.; Turpeinen, M.

2007-01-01

In this deliverable, the WP5 partners present the results of the FUGA construct validity studies. The objective of the WP5 was to establish the construct validity of the different potential measures of game experience based on the different measurement techniques. This was the first step to ensure

Application of semi-empirical modeling and non-linear regression to unfolding fast neutron spectra from integral reaction rate data

International Nuclear Information System (INIS)

Harker, Y.D.

1976-01-01

A semi-empirical analytical expression representing a fast reactor neutron spectrum has been developed. This expression was used in a non-linear regression computer routine to obtain from measured multiple foil integral reaction data the neutron spectrum inside the Coupled Fast Reactivity Measurement Facility. In this application six parameters in the analytical expression for neutron spectrum were adjusted in the non-linear fitting process to maximize consistency between calculated and measured integral reaction rates for a set of 15 dosimetry detector foils. In two-thirds of the observations the calculated integral agreed with its respective measured value to within the experimental standard deviation, and in all but one case agreement within two standard deviations was obtained. Based on this quality of fit the estimated 70 to 75 percent confidence intervals for the derived spectrum are 10 to 20 percent for the energy range 100 eV to 1 MeV, 10 to 50 percent for 1 MeV to 10 MeV and 50 to 90 percent for 10 MeV to 18 MeV. The analytical model has demonstrated a flexibility to describe salient features of neutron spectra of the fast reactor type. The use of regression analysis with this model has produced a stable method to derive neutron spectra from a limited amount of integral data

Using a tag team of undergraduate researchers to construct an empirical model of auroral Poynting flux, from satellite data

Science.gov (United States)

Cosgrove, R. B.; Bahcivan, H.; Klein, A.; Ortega, J.; Alhassan, M.; Xu, Y.; Chen, S.; Van Welie, M.; Rehberger, J.; Musielak, S.; Cahill, N.

2012-12-01

Empirical models of the incident Poynting flux and particle kinetic energy flux, associated with auroral processes, have been constructed using data from the FAST satellite. The models were constructed over a three-year period by a tag-team of three groups of undergraduate researchers from Worcester Polytechnic Institute (WPI), working under the supervision of researchers at SRI International, a nonprofit research institute. Each group spent one academic quarter in residence at SRI, in fulfillment of WPI's Major Qualifying Project (MQP), required for graduation from the Department of Electrical and Computer Engineering. The MQP requires a written group report, which was used to transition from one group to the next. The student's research involved accessing and processing a data set of 20,000 satellite orbits, replete with flaws associated with instrument failures, which had to be removed. The data had to be transformed from the satellite reference frame into solar coordinates, projected to a reference altitude, sorted according to geophysical conditions, and etc. The group visits were chaperoned by WPI, and were jointly funded. Researchers at SRI were supported by a grant from the National Science Foundation, which was tailored to accommodate the undergraduate tag-team approach. The NSF grant extended one year beyond the student visits, with increased funding in the final year, permitting the researchers at SRI to exercise quality control, and to produce publications. It is expected that the empirical models will be used as inputs to large-scale general circulation models (GCMs), to specify the atmospheric heating rate at high altitudes.; Poynting Flux with northward IMF ; Poynting flux with southward IMF

“Empire is a state of mind” – Imagining Eurasia in Russia –

OpenAIRE

Vehkasalo, Veera Kaisa

2011-01-01

In this thesis I study the Neo-Eurasianist movement in Russia and the ways the activists of the movement construct Eurasia as a unified entity and an empire. The central research questions of this work are: What is the empire and what are its central motivations and themes? How is the idea of empire constructed or understood, and how can this be interpreted? What could be seen to be the effects of their ways of imagining Eurasia? My material consists of interviews that were collected during t...

Emotional Intelligence and Social Interest : are they related constructs?

OpenAIRE

Chamarro Lusar, Andrés

2012-01-01

In the last 15 years, a new psychological construct has emerged in the field of psychology: Emotional Intelligence. Some models of Emotional Intelligence bear ressemblence with aspects of one of the core constructs of Adlerian Psychology: Social Interest. The authors investigated, if both constructs are also empirically related and which is their capacity to predict psychiatric symptoms and antisocial behavior. Results indicate that Social Interest and Emotional Intelligence are empirically d...

Construction and operation costs of constructed wetlands treating wastewater.

Science.gov (United States)

Gkika, Dimitra; Gikas, Georgios D; Tsihrintzis, Vassilios A

2014-01-01

Design data from nine constructed wetlands (CW) facilities of various capacities (population equivalent (PE)) are used to estimate construction and operation costs, and then to derive empirical equations relating the required facility land area and the construction cost to PE. In addition, comparisons between the costs of CW facilities based on various alternative construction materials, i.e., reinforced concrete and earth structures (covered with either high density polyethylene or clay), are presented in relation to the required area. The results show that earth structures are economically advantageous. The derived equations can be used for providing a preliminary cost estimate of CW facilities for domestic wastewater treatment.

Semi-empirical procedures for correcting detector size effect on clinical MV x-ray beam profiles

International Nuclear Information System (INIS)

Sahoo, Narayan; Kazi, Abdul M.; Hoffman, Mark

2008-01-01

The measured radiation beam profiles need to be corrected for the detector size effect to derive the real profiles. This paper describes two new semi-empirical procedures to determine the real profiles of high-energy x-ray beams by removing the detector size effect from the measured profiles. Measured profiles are corrected by shifting the position of each measurement point by a specific amount determined from available theoretical and experimental knowledge in the literature. The authors developed two procedures to determine the amount of shift. In the first procedure, which employs the published analytical deconvolution procedure of other investigators, the shift is determined from the comparison of the analytical fit of the measured profile and the corresponding analytical real profile derived from the deconvolution of the fitted measured profile and the Gaussian detector response function. In the second procedure, the amount of shift at any measurement point is considered to be proportional to the value of an analytical function related to the second derivative of the real profile at that point. The constant of proportionality and a parameter in the function are obtained from the values of the shifts at the 90%, 80%, 20%, and 10% dose levels, which are experimentally known from the published results of other investigators to be approximately equal to half of the radius of the detector. These procedures were tested by correcting the profiles of 6 and 18 MV x-ray beams measured by three different ionization chambers and a stereotactic field diode detector with 2.75, 2, 1, and 0.3 mm radii of their respective active cylindrical volumes. The corrected profiles measured by different detectors are found to be in close agreement. The detector size corrected penumbra widths also agree with the expected values based on the results of an earlier investigation. Thus, the authors concluded that the proposed procedures are accurate and can be used to derive the real

Period of sunspot numbers is 11. 02653720 years (11 years 9 days 16 hours 18 minutes 0 seconds)

Energy Technology Data Exchange (ETDEWEB)

Norita, S [Miyazaki Univ. (Japan). Faculty of Engineering

1976-09-01

In the statistical analysis of time series there have been applied usually the stationary stochastic process or the Markov stochastic process and recently there are applied remarkably an autoregressive process, a stochastic difference equation, an autoregressive-moving average process, a moving average process, the Whittaker periodogram, the correlogram, Schuster periodogram, chi-squared periodogram, level crossings, harmonic process, difference method, spectral density and first order vector equation, but in special case it is desirable to apply the nonstationary stocastic process. In this paper we introduce a stationarity into the autoregressive process and then it is the first purpose to compute precisely the period of sunspot numbers. The result up to the eighth places at the decimal point was obtained that its period is 11.02653720 years, that is, 11 years 9 days 16 hours 18 minutes 0 seconds. This is considered to be more relevant than numerical values by which Schuster (1906) and Yule (1927) had calculated the respective 11.125 years and 10.60 years in the past. We revised the theoretical expression in the thesis of Anderson, Shaman, Lindgren, Brillinger, Newbold, Parzen, Kingman, Van Ness and Kenneth, etc. and executed the numerical analysis of period of sunspot numbers investigated now.

Period of sunspot numbers is 11.02653720 years (11 years 9 days 16 hours 18 minutes 0 seconds)

International Nuclear Information System (INIS)

Norita, Sadataka

1976-01-01

In the statistical analysis of time series there have been applied usually the stationary stochastic process or the Markov stochastic process and recently there are applied remarkably an autoregressive process, a stochastic difference equation, an autoregressive-moving average process, a moving average process, the Whittaker periodogram, the correlogram, Schuster periodogram, chi-squared periodogram, level crossings, harmonic process, difference method, spectral density and first order vector equation, but in special case it is desirable to apply the nonstationary stocastic process. In this paper we introduce an stationarity into the autoregressive process and then it is the first purpose to compute precisely period of sunspot numbers. The result up to the eighth places at the decimal point was obtained that its period is 11.02653720 years, that is, 11 years 9 days 16 hours 18 minutes 0 seconds. This is considered to be more relevant than numerical values by which Schuster (1906) and Yule (1927) had calculated the respective 11.125 years and 10.60 years in the past. We revised the theoretical expression in the thesis of Anderson, Shaman, Lindgren, Brillinger, Newbold, Parzen, Kingman, Van Ness and Kenneth, etc. and executed the numerical analysis of period of sunspot numbers investigated now. (auth.)

Extending Counter-streaming Motion from an Active Region Filament to a Sunspot Light Bridge

Science.gov (United States)

Wang, Haimin; Liu, Rui; Li, Qin; Liu, Chang; Deng, Na; Xu, Yan; Jing, Ju; Wang, Yuming; Cao, Wenda

2018-01-01

We analyze high-resolution observations from the 1.6 m telescope at Big Bear Solar Observatory that cover an active region filament. Counter-streaming motions are clearly observed in the filament. The northern end of the counter-streaming motions extends to a light bridge, forming a spectacular circulation pattern around a sunspot, with clockwise motion in the blue wing and counterclockwise motion in the red wing, as observed in the Hα off-bands. The apparent speed of the flow is around 10–60 km s‑1 in the filament, decreasing to 5–20 km s‑1 in the light bridge. The most intriguing results are the magnetic structure and the counter-streaming motions in the light bridge. Similar to those in the filament, the magnetic fields show a dominant transverse component in the light bridge. However, the filament is located between opposed magnetic polarities, while the light bridge is between strong fields of the same polarity. We analyze the power of oscillations with the image sequences of constructed Dopplergrams, and find that the filament’s counter-streaming motion is due to physical mass motion along fibrils, while the light bridge’s counter-streaming motion is due to oscillation in the direction along the line-of-sight. The oscillation power peaks around 4 minutes. However, the section of the light bridge next to the filament also contains a component of the extension of the filament in combination with the oscillation, indicating that some strands of the filament are extended to and rooted in that part of the light bridge.

The role of production and teamwork practices in construction safety: a cognitive model and an empirical case study.

Science.gov (United States)

Mitropoulos, Panagiotis Takis; Cupido, Gerardo

2009-01-01

In construction, the challenge for researchers and practitioners is to develop work systems (production processes and teams) that can achieve high productivity and high safety at the same time. However, construction accident causation models ignore the role of work practices and teamwork. This study investigates the mechanisms by which production and teamwork practices affect the likelihood of accidents. The paper synthesizes a new model for construction safety based on the cognitive perspective (Fuller's Task-Demand-Capability Interface model, 2005) and then presents an exploratory case study. The case study investigates and compares the work practices of two residential framing crews: a 'High Reliability Crew' (HRC)--that is, a crew with exceptional productivity and safety over several years, and an average performing crew from the same company. The model explains how the production and teamwork practices generate the work situations that workers face (the task demands) and affect the workers ability to cope (capabilities). The case study indicates that the work practices of the HRC directly influence the task demands and match them with the applied capabilities. These practices were guided by the 'principle' of avoiding errors and rework and included work planning and preparation, work distribution, managing the production pressures, and quality and behavior monitoring. The Task Demand-Capability model links construction research to a cognitive model of accident causation and provides a new way to conceptualize safety as an emergent property of the production practices and teamwork processes. The empirical evidence indicates that the crews' work practices and team processes strongly affect the task demands, the applied capabilities, and the match between demands and capabilities. The proposed model and the exploratory case study will guide further discovery of work practices and teamwork processes that can increase both productivity and safety in construction

Semi-empirical correlation for binary interaction parameters of the Peng–Robinson equation of state with the van der Waals mixing rules for the prediction of high-pressure vapor–liquid equilibrium

Directory of Open Access Journals (Sweden)

Seif-Eddeen K. Fateen

2013-03-01

Full Text Available Peng–Robinson equation of state is widely used with the classical van der Waals mixing rules to predict vapor liquid equilibria for systems containing hydrocarbons and related compounds. This model requires good values of the binary interaction parameter kij. In this work, we developed a semi-empirical correlation for kij partly based on the Huron–Vidal mixing rules. We obtained values for the adjustable parameters of the developed formula for over 60 binary systems and over 10 categories of components. The predictions of the new equation system were slightly better than the constant-kij model in most cases, except for 10 systems whose predictions were considerably improved with the new correlation.

Phenomenological aspects of the cognitive rumination construct.

Science.gov (United States)

Meyer, Leonardo Fernandez; Taborda, José Geraldo Vernet; da Costa, Fábio Antônio; Soares, Ana Luiza Alfaya Galego; Mecler, Kátia; Valença, Alexandre Martins

2015-01-01

To evaluate the importance of phenomenological aspects of the cognitive rumination (CR) construct in current empirical psychiatric research. We searched SciELO, Scopus, ScienceDirect, MEDLINE, OneFile (GALE), SpringerLink, Cambridge Journals and Web of Science between February and March of 2014 for studies whose title and topic included the following keywords: cognitive rumination; rumination response scale; and self-reflection. The inclusion criteria were: empirical clinical study; CR as the main object of investigation; and study that included a conceptual definition of CR. The studies selected were published in English in biomedical journals in the last 10 years. Our phenomenological analysis was based on Karl Jaspers' General Psychopathology. Most current empirical studies adopt phenomenological cognitive elements in conceptual definitions. However, these elements do not seem to be carefully examined and are indistinctly understood as objective empirical factors that may be measured, which may contribute to misunderstandings about CR, erroneous interpretations of results and problematic theoretical models. Empirical studies fail when evaluating phenomenological aspects of the cognitive elements of the CR construct. Psychopathology and phenomenology may help define the characteristics of CR elements and may contribute to their understanding and hierarchical organization as a construct. A review of the psychopathology principles established by Jasper may clarify some of these issues.

Semi-direct sums of Lie algebras and continuous integrable couplings

International Nuclear Information System (INIS)

Ma Wenxiu; Xu Xixiang; Zhang Yufeng

2006-01-01

A relation between semi-direct sums of Lie algebras and integrable couplings of continuous soliton equations is presented, and correspondingly, a feasible way to construct integrable couplings is furnished. A direct application to the AKNS spectral problem leads to a novel hierarchy of integrable couplings of the AKNS hierarchy of soliton equations. It is also indicated that the study of integrable couplings using semi-direct sums of Lie algebras is an important step towards complete classification of integrable systems

Capital-labor substitution and competitive non-linear endogenous business cycles

NARCIS (Netherlands)

Grandmont, J.M.; Pintus, P.; de Vilder, R.

1998-01-01

We develop simple geometrical methods to study local indeterminacy, bifurcations, and stochastic (sunspot) equilibria near a steady state, in nonlinear two dimensional economic models. We present in particular a simple, constructive, geometrical characterization of the support of stochastic sunspot

A comparison between highly resolved S-component observations and model calculations using force-free magnetic field extrapolations

International Nuclear Information System (INIS)

Seehafer, N.; Hildebrandt, J.; Krueger, A.; Akhmedov, Sh.; Gel'frejkh, G.B.

1983-01-01

Extensive model calculations of solar radio emission features were presented for the complex of solar active regions Hale No 16862, 16863, and 16864 on May 27, 1980 using force-free extrapolated magnetic fields with constant α and a treatment of radiative transfer of S-component emission. The photospheric magnetic field data were taken from magnetographic measurements whereas the required height distribution of temperature and electron density have been adopted from semi-empirical sunspot models based on recent X-, EUV-, optical, and radio observations. In contrast to the simpler magnetic field structure used in other studies, the complex source structure of the S-component emission is clearly represented by other characteristics. The results of the calculations are compared with the observations of the WRST (6 cm) and RATAN-600 (3.2 cm). (author)

Semi-supervised eigenvectors for large-scale locally-biased learning

DEFF Research Database (Denmark)

Hansen, Toke Jansen; Mahoney, Michael W.

2014-01-01

improved scaling properties. We provide several empirical examples demonstrating how these semi-supervised eigenvectors can be used to perform locally-biased learning; and we discuss the relationship between our results and recent machine learning algorithms that use global eigenvectors of the graph......In many applications, one has side information, e.g., labels that are provided in a semi-supervised manner, about a specific target region of a large data set, and one wants to perform machine learning and data analysis tasks nearby that prespecified target region. For example, one might......-based machine learning and data analysis tools. At root, the reason is that eigenvectors are inherently global quantities, thus limiting the applicability of eigenvector-based methods in situations where one is interested in very local properties of the data. In this paper, we address this issue by providing...

Denoising traffic collision data using ensemble empirical mode decomposition (EEMD) and its application for constructing continuous risk profile (CRP).

Science.gov (United States)

Kim, Nam-Seog; Chung, Koohong; Ahn, Seongchae; Yu, Jeong Whon; Choi, Keechoo

2014-10-01

Filtering out the noise in traffic collision data is essential in reducing false positive rates (i.e., requiring safety investigation of sites where it is not needed) and can assist government agencies in better allocating limited resources. Previous studies have demonstrated that denoising traffic collision data is possible when there exists a true known high collision concentration location (HCCL) list to calibrate the parameters of a denoising method. However, such a list is often not readily available in practice. To this end, the present study introduces an innovative approach for denoising traffic collision data using the Ensemble Empirical Mode Decomposition (EEMD) method which is widely used for analyzing nonlinear and nonstationary data. The present study describes how to transform the traffic collision data before the data can be decomposed using the EEMD method to obtain set of Intrinsic Mode Functions (IMFs) and residue. The attributes of the IMFs were then carefully examined to denoise the data and to construct Continuous Risk Profiles (CRPs). The findings from comparing the resulting CRP profiles with CRPs in which the noise was filtered out with two different empirically calibrated weighted moving window lengths are also documented, and the results and recommendations for future research are discussed. Published by Elsevier Ltd.

Phenomenological aspects of the cognitive rumination construct

Directory of Open Access Journals (Sweden)

Leonardo Fernandez Meyer

2015-03-01

Full Text Available Objective: To evaluate the importance of phenomenological aspects of the cognitive rumination (CR construct in current empirical psychiatric research.Method: We searched SciELO, Scopus, ScienceDirect, MEDLINE, OneFile (GALE, SpringerLink, Cambridge Journals and Web of Science between February and March of 2014 for studies whose title and topic included the following keywords: cognitive rumination; rumination response scale; and self-reflection. The inclusion criteria were: empirical clinical study; CR as the main object of investigation; and study that included a conceptual definition of CR. The studies selected were published in English in biomedical journals in the last 10 years. Our phenomenological analysis was based on Karl Jaspers' General Psychopathology.Results: Most current empirical studies adopt phenomenological cognitive elements in conceptual definitions. However, these elements do not seem to be carefully examined and are indistinctly understood as objective empirical factors that may be measured, which may contribute to misunderstandings about CR, erroneous interpretations of results and problematic theoretical models.Conclusion: Empirical studies fail when evaluating phenomenological aspects of the cognitive elements of the CR construct. Psychopathology and phenomenology may help define the characteristics of CR elements and may contribute to their understanding and hierarchical organization as a construct. A review of the psychopathology principles established by Jasper may clarify some of these issues.

Stokes profile analysis and vector magnetic fields. III. Extended temperature minima of sunspot umbrae as inferred from Stokes profiles of Mg I 4571 A

International Nuclear Information System (INIS)

Lites, B.W.; Skumanich, A.; Rees, D.E.; Murphy, G.A.; Carlsson, M.; Sydney Univ., Australia; Oslo Universitetet, Norway)

1987-01-01

Observed Stokes profiles of Mg I 4571 A are analyzed as a diagnostic of the magnetic field and thermal structure at the temperature minimum of sunspot umbrae. Multilevel non-LTE transfer calculations of the Mg I-II-III excitation and ionization balance in model umbral atmospheres show: (1) Mg I to be far less ionized in sunspot umbrae than in the quiet sun, leading to greatly enhanced opacity in 4571 A, and (2) LTE excitation of 4571 A. Existing umbral models predict emission cores of the Stokes I profile due to the chromospheric temperature rise. This feature is not present in observed umbral profiles. Moreover, such an emission reversal causes similar anomalous features in the Stokes Q, U, V profiles, which are also not observed. Umbral atmospheres with extended temperature minima are suggested. Implications for chromospheric heating mechanisms and the utility of this line for solar vector magnetic field measurements are discussed. 35 references

Factors contributing to the fluctuations in residential construction in Iran

Directory of Open Access Journals (Sweden)

Hassan Gholipour Fereidouni

2011-12-01

Full Text Available Residential construction is one of the most important pillars of Iran’s economy. Although this sector had an increasing trend over the past two decades, however, the growth rate of residential construction was very volatile. The purpose of this paper is to empirically investigate those factors contributing to this fluctuation over the 1991:Q2-2008:Q4. By applying cointegration approach, the empirical results show that housing prices, construction costs, GDP and gold prices are important factors to explain swings in residential construction in Iran.

Empirical Model Building Data, Models, and Reality

CERN Document Server

Thompson, James R

2011-01-01

Praise for the First Edition "This...novel and highly stimulating book, which emphasizes solving real problems...should be widely read. It will have a positive and lasting effect on the teaching of modeling and statistics in general." - Short Book Reviews This new edition features developments and real-world examples that showcase essential empirical modeling techniques Successful empirical model building is founded on the relationship between data and approximate representations of the real systems that generated that data. As a result, it is essential for researchers who construct these m

Water balance of two earthen landfill caps in a semi-arid climate

International Nuclear Information System (INIS)

Khire, M.V.; Benson, C.H.; Bosscher, P.J.

1997-01-01

Water balance data are presented that were obtained from two earthen cap test sections located in a semi-arid region. The test sections were constructed on a municipal solid waste landfill in East Wenatchee, Washington, USA. One test section represents a traditional resistive barrier, and is constructed with a compacted silty clay barrier 60 cm thick and a vegetated silty clay surface layer 15 cm thick. The other test section represents a capillary barrier and has a sand layer 75 cm thick overlain by a 15-cm-thick vegetated surface layer of silt. Extensive hydrological and meteorological data have been collected since November 1992. Unsaturated hydraulic properties of soils, hydrologic parameters, and vegetation have been extensively characterized. Results of the study show that capillary barriers can be effective caps in semi-arid and arid regions. They are also cheaper to construct and can perform better than traditional resistive barriers

Measurement of polarization curve and development of a unique semi-empirical model for description of PEMFC and DMFC performances

Directory of Open Access Journals (Sweden)

M. SHAKERI

2011-06-01

Full Text Available In this study, a single polymer electrolyte membrane fuel cell (PEMFC in H2/ /O2 form with an effective dimension of 5 cm5 cm as well as a single direct methanol fuel cell (DMFC with a dimension of 10 cm10 cm were fabricated. In an existing test station, the voltage-current density performances of the fabricated PEMFC and DMFC were examined under various operating conditions. As expected, DMFC showed a lower electrical performance which can be attributed to the slower methanol oxidation rate in comparison to the hydrogen oxidation. The results obtained from the cell operation indicated that the temperature has a great effect on the cell performance. At 60 C, the best power output was obtained for PEMFC. There was a drop in the cell voltage beyond 60 C, which can be attributed to the reduction of water content inside the membrane. For DMFC, the maximum power output resulted at 64 C. Increasing oxygen stoichiometry and total cell pressure had a marginal effect on the cell performance. The results also revealed that the cell performance improved by increasing pressure differences between the anode and cathode. A unified semi-empirical thermodynamic based model was developed to describe the cell voltage as a function of current density for both kinds of fuel cells. The model equation parameters were obtained through a nonlinear fit to the experimental data. There was a good agreement between the experimental data and the model predicted cell performance for both types of fuel cells.

Construction of semi-underground type power plant in close vicinity of existing structures. Kisetsu kozobutsu ni kinsetsu shita han chika shiki hatsudensho no seko

Energy Technology Data Exchange (ETDEWEB)

Saito, K [Toshiba Ceramics Co. Ltd., Tokyo (Japan); Suda, H [Nippon Koei CO. Ltd., Tokyo (Japan); Kanazawa, S [Hazama-Gumi Ltd., Tokyo (Japan)

1991-01-30

The second Akashiba power station is of a semi-underground type and located on a steep slope between the Arakawa River and a national road. Therefore, there were many such problems to be solved for its construction as safety precaution for steep slope ground including the closely located national road, underwater work for the intake and outlet works, construction of tunnel below the present water level of the river in which deluges can be expected. Very severe conditions were imposed for the plan of the retaining walls, which are required for the prevention of landslide on the national road side, because of the problems of boundaries of the site, proprietary right, etc. The plan and design were studied for 3 cases, i.e. during drilling, at regular time and at the time of earthquake occurrence. Outlines of the drilling of the power plant shaft, mucking, timbering, spraying and spring water treatment are given. In connection with the control of measurement, subjects for measurement and the result of measurement are reported. Although this construction work was carried out under very severe conditions, it was completed in August, 1990 with no serious disaster. 13 figs., 5 tabs.

A Framework for Analysing Driver Interactions with Semi-Autonomous Vehicles

Directory of Open Access Journals (Sweden)

Siraj Shaikh

2012-12-01

Full Text Available Semi-autonomous vehicles are increasingly serving critical functions in various settings from mining to logistics to defence. A key characteristic of such systems is the presence of the human (drivers in the control loop. To ensure safety, both the driver needs to be aware of the autonomous aspects of the vehicle and the automated features of the vehicle built to enable safer control. In this paper we propose a framework to combine empirical models describing human behaviour with the environment and system models. We then analyse, via model checking, interaction between the models for desired safety properties. The aim is to analyse the design for safe vehicle-driver interaction. We demonstrate the applicability of our approach using a case study involving semi-autonomous vehicles where the driver fatigue are factors critical to a safe journey.

Research on Semi-automatic Bomb Fetching for an EOD Robot

Directory of Open Access Journals (Sweden)

Qian Jun

2008-11-01

Full Text Available An EOD robot system, SUPER-PLUS, which has a novel semi-automatic bomb fetching function is presented in this paper. With limited support of human, SUPER-PLUS scans the cluttered environment with a wrist-mounted laser distance sensor and plans the manipulator a collision free path to fetch the bomb. The model construction of manipulator, bomb and environment, C-space map, path planning and the operation procedure are introduced in detail. The semi-automatic bomb fetching function has greatly improved the operation performance of EOD robot.

Research on Semi-Automatic Bomb Fetching for an EOD Robot

Directory of Open Access Journals (Sweden)

Zeng Jian-Jun

2007-06-01

Full Text Available An EOD robot system, SUPER-PLUS, which has a novel semi-automatic bomb fetching function is presented in this paper. With limited support of human, SUPER-PLUS scans the cluttered environment with a wrist-mounted laser distance sensor and plans the manipulator a collision free path to fetch the bomb. The model construction of manipulator, bomb and environment, C-space map, path planning and the operation procedure are introduced in detail. The semi-automatic bomb fetching function has greatly improved the operation performance of EOD robot.

Semi-empirical relationship between the hardness, grain size and mean free path of WC-Co

CSIR Research Space (South Africa)

Makhele-Lekala, L

2001-01-01

Full Text Available , grain size of WC and mean free path in Co was obtained. It was found that the empirical formula fitted our measured hardness well. However, when used against results of other researchers, it did not reproduce them satisfactorily at values higher than...

EVIDENCE FOR A TRANSITION REGION RESPONSE TO PENUMBRAL MICROJETS IN SUNSPOTS

International Nuclear Information System (INIS)

Vissers, G. J. M.; Rouppe van der Voort, L. H. M.; Carlsson, M.

2015-01-01

Penumbral microjets (PMJs) are short-lived, fine-structured, and bright jets that are generally observed in chromospheric imaging of the penumbra of sunspots. Here we investigate their potential transition region signature by combining observations with the Swedish 1-m Solar Telescope in the Ca ii H and Ca ii 8542 Å lines with ultraviolet imaging and spectroscopy obtained with the Interface Region Imaging Spectrograph (IRIS), which includes the C ii 1334/1335 Å, Si iv 1394/1403 Å, and Mg ii h and k 2803/2796 Å lines. We find a clear corresponding signal in the IRIS Mg ii k, C ii, and Si iv slit-jaw images, typically offset spatially from the Ca ii signature in the direction along the jets: from base to top, the PMJs are predominantly visible in Ca ii, Mg ii k, and C ii/Si iv, suggesting progressive heating to transition region temperatures along the jet extent. Hence, these results support the suggestion from earlier studies that PMJs may heat to transition region temperatures

An Empirical Study of Atmospheric Correction Procedures for Regional Infrasound Amplitudes with Ground Truth.

Science.gov (United States)

Howard, J. E.

2014-12-01

This study focusses on improving methods of accounting for atmospheric effects on infrasound amplitudes observed on arrays at regional distances in the southwestern United States. Recordings at ranges of 150 to nearly 300 km from a repeating ground truth source of small HE explosions are used. The explosions range in actual weight from approximately 2000-4000 lbs. and are detonated year-round which provides signals for a wide range of atmospheric conditions. Three methods of correcting the observed amplitudes for atmospheric effects are investigated with the data set. The first corrects amplitudes for upper stratospheric wind as developed by Mutschlecner and Whitaker (1999) and uses the average wind speed between 45-55 km altitudes in the direction of propagation to derive an empirical correction formula. This approach was developed using large chemical and nuclear explosions and is tested with the smaller explosions for which shorter wavelengths cause the energy to be scattered by the smaller scale structure of the atmosphere. The second approach isa semi-empirical method using ray tracing to determine wind speed at ray turning heights where the wind estimates replace the wind values in the existing formula. Finally, parabolic equation (PE) modeling is used to predict the amplitudes at the arrays at 1 Hz. The PE amplitudes are compared to the observed amplitudes with a narrow band filter centered at 1 Hz. An analysis is performed of the conditions under which the empirical and semi-empirical methods fail and full wave methods must be used.

Ensemble learning with trees and rules: supervised, semi-supervised, unsupervised

Science.gov (United States)

In this article, we propose several new approaches for post processing a large ensemble of conjunctive rules for supervised and semi-supervised learning problems. We show with various examples that for high dimensional regression problems the models constructed by the post processing the rules with ...

Semi-empirical determination of the diffusion coefficient of the Fricke Xylenol Gel dosimeter through finite difference methods; Determinacao semi-empirica do coeficiente de difusao do dosimetro Fricke Xilenol Gel atraves do metodo de diferencas finitas

Energy Technology Data Exchange (ETDEWEB)

Nascimento, E.O.; Oliveira, L.N., E-mail: lucas@ifg.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Goias (IFG), Goiania, GO (Brazil)

2014-11-01

Partial Differential Equations (PDE) can model natural phenomena, such as related to physics, chemistry and engineering. For these classes of equations, analytical solutions are difficult to be obtained, so a computational approach is indicted. In this context, the Finite Difference Method (FDM) can provide useful tools for the field of Medical Physics. In this study, is described the implementation of a computational mesh, in order to be used in determining the Diffusion Coefficient (DC) of the Fricke Xylenol Gel dosimeter (FXG). The initial and boundary conditions both referred by experimental factors are modelled in FDM, thus making a semi-empirical study in determining the DC. Together, the method of Reflection and Superposition (SRM) and the analysis of experimental data, served as first validation for the simulation. Such methodologies interface generated concordant results for a range of error of 3% in concentration lines for small times when compared to the analytical solution. The result for the DC was 0.43 mm{sup 2} /h. This value is in concordance with measures parameters range found in polymer gels dosimeters: 0.3-2.0 mm{sup 2} /h. Therefore, the application of computer simulation methodology supported by the FDM may be used in determining the diffusion coefficient in FXG dosimeter. (author)

STUDY OF RAPID FORMATION OF A δ SUNSPOT ASSOCIATED WITH THE 2012 JULY 2 C7.4 FLARE USING HIGH-RESOLUTION OBSERVATIONS OF THE NEW SOLAR TELESCOPE

International Nuclear Information System (INIS)

Wang Haimin; Liu Chang; Wang Shuo; Deng Na; Xu Yan; Jing Ju; Cao Wenda

2013-01-01

Rapid, irreversible changes of magnetic topology and sunspot structure associated with flares have been systematically observed in recent years. The most striking features include the increase of the horizontal field at the polarity inversion line (PIL) and the co-spatial penumbral darkening. A likely explanation of the above phenomenon is the back reaction to the coronal restructuring after eruptions: a coronal mass ejection carries the upward momentum while the downward momentum compresses the field lines near the PIL. Previous studies could only use low-resolution (above 1'') magnetograms and white-light images. Therefore, the changes are mostly observed for X-class flares. Taking advantage of the 0.''1 spatial resolution and 15 s temporal cadence of the New Solar Telescope at the Big Bear Solar Observatory, we report in detail the rapid formation of sunspot penumbra at the PIL associated with the C7.4 flare on 2012 July 2. It is unambiguously shown that the solar granulation pattern evolves to an alternating dark and bright fibril structure, the typical pattern of penumbra. Interestingly, the appearance of such a penumbra creates a new δ sunspot. The penumbral formation is also accompanied by the enhancement of the horizontal field observed using vector magnetograms from the Helioseismic and Magnetic Imager. We explain our observations as being due to the eruption of a flux rope following magnetic cancellation at the PIL. Subsequently, the re-closed arcade fields are pushed down toward the surface to form the new penumbra. NLFFF extrapolation clearly shows both the flux rope close to the surface and the overlying fields

Stability and mobility of self-interstitials and small interstitial clusters in α-iron: ab initio and empirical potential calculations

International Nuclear Information System (INIS)

Willaime, F.; Fu, C.C.; Marinica, M.C.; Dalla Torre, J.

2005-01-01

The stability and mobility of self-interstitials and small interstitial clusters, I n , in α-Fe is investigated by means of calculations performed in the framework of the density functional theory using the SIESTA code. The mono-, di- and tri-interstitials are shown to be made of (parallel) dumbbells and to migrate by nearest-neighbor translation-rotation jumps, according to Johnson's mechanism. The orientation of the dumbbells becomes energetically more favourable for I 5 and larger clusters. The performance of a semi-empirical potential recently developed for Fe, including ab initio self-interstitial data in the fitted properties, is evaluated over the present results. The superiority over previous semi-empirical potentials is confirmed. Finally the impact of the present results on the formation mechanism of loops, observed experimentally in α-Fe is discussed

Quantitative analyses of empirical fitness landscapes

International Nuclear Information System (INIS)

Szendro, Ivan G; Franke, Jasper; Krug, Joachim; Schenk, Martijn F; De Visser, J Arjan G M

2013-01-01

The concept of a fitness landscape is a powerful metaphor that offers insight into various aspects of evolutionary processes and guidance for the study of evolution. Until recently, empirical evidence on the ruggedness of these landscapes was lacking, but since it became feasible to construct all possible genotypes containing combinations of a limited set of mutations, the number of studies has grown to a point where a classification of landscapes becomes possible. The aim of this review is to identify measures of epistasis that allow a meaningful comparison of fitness landscapes and then apply them to the empirical landscapes in order to discern factors that affect ruggedness. The various measures of epistasis that have been proposed in the literature appear to be equivalent. Our comparison shows that the ruggedness of the empirical landscape is affected by whether the included mutations are beneficial or deleterious and by whether intragenic or intergenic epistasis is involved. Finally, the empirical landscapes are compared to landscapes generated with the rough Mt Fuji model. Despite the simplicity of this model, it captures the features of the experimental landscapes remarkably well. (paper)

Forces in wingwalls from thermal expansion of skewed semi-integral bridges.

Science.gov (United States)

2010-11-01

Jointless bridges, such as semi-integral and integral bridges, have become more popular in recent years because of their simplicity in the construction and the elimination of high costs related to joint maintenance. Prior research has shown that skew...

Predicting membrane flux decline from complex mixtures using flow-field flow fractionation measurements and semi-empirical theory.

Science.gov (United States)

Pellegrino, J; Wright, S; Ranvill, J; Amy, G

2005-01-01

Flow-Field Flow Fractionation (FI-FFF) is an idealization of the cross flow membrane filtration process in that, (1) the filtration flux and crossflow velocity are constant from beginning to end of the device, (2) the process is a relatively well-defined laminar-flow hydrodynamic condition, and (3) the solutes are introduced as a pulse-input that spreads due to interactions with each other and the membrane in the dilute-solution limit. We have investigated the potential for relating FI-FFF measurements to membrane fouling. An advection-dispersion transport model was used to provide 'ideal' (defined as spherical, non-interacting solutes) solute residence time distributions (RTDs) for comparison with 'real' RTDs obtained experimentally at different cross-field velocities and solution ionic strength. An RTD moment analysis based on a particle diameter probability density function was used to extract "effective" characteristic properties, rather than uniquely defined characteristics, of the standard solute mixture. A semi-empirical unsteady-state, flux decline model was developed that uses solute property parameters. Three modes of flux decline are included: (1) concentration polarization, (2) cake buildup, and (3) adsorption on/in pores, We have used this model to test the hypothesis-that an analysis of a residence time distribution using FI-FFF can describe 'effective' solute properties or indices that can be related to membrane flux decline in crossflow membrane filtration. Constant flux filtration studies included the changes of transport hydrodynamics (solvent flux to solute back diffusion (J/k) ratios), solution ionic strength, and feed water composition for filtration using a regenerated cellulose ultrafiltration membrane. Tests of the modeling hypothesis were compared with experimental results from the filtration measurements using several correction parameters based on the mean and variance of the solute RTDs. The corrections used to modify the boundary layer

A simple semi-empirical approach to model thickness of ash-deposits for different eruption scenarios

Directory of Open Access Journals (Sweden)

A. O. González-Mellado

2010-11-01

Full Text Available The impact of ash-fall on people, buildings, crops, water resources, and infrastructure depends on several factors such as the thickness of the deposits, grain size distribution and others. Preparedness against tephra falls over large regions around an active volcano requires an understanding of all processes controlling those factors, and a working model capable of predicting at least some of them. However, the complexity of tephra dispersion and sedimentation makes the search of an integral solution an almost unapproachable problem in the absence of highly efficient computing facilities due to the large number of equations and unknown parameters that control the process. An alternative attempt is made here to address the problem of modeling the thickness of ash deposits as a primary impact factor that can be easily communicated to the public and decision-makers. We develop a semi-empirical inversion model to estimate the thickness of non-compacted deposits produced by an explosive eruption around a volcano in the distance range 4–150 km from the eruptive source.

The model was elaborated from the analysis of the geometric distribution of deposit thickness of 14 world-wide well-documented eruptions. The model was initially developed to depict deposits of potential eruptions of Popocatépetl and Colima volcanoes in México, but it can be applied to any volcano. It has been designed to provide planners and Civil Protection authorities of an accurate perception of the ash-fall deposit thickness that may be expected for different eruption scenarios. The model needs to be fed with a few easy-to-obtain parameters, namely, height of the eruptive column, duration of the explosive phase, and wind speed and direction, and its simplicity allows it to run in any platform, including a personal computers and even a notebook. The results may be represented as tables, two dimensional thickness-distance plots, or isopach maps using any available

Application Of A New Semi-Empirical Model For Forming Limit Prediction Of Sheet Material Including Superposed Loads Of Bending And Shearing

Science.gov (United States)

Held, Christian; Liewald, Mathias; Schleich, Ralf; Sindel, Manfred

2010-06-01

The use of lightweight materials offers substantial strength and weight advantages in car body design. Unfortunately such kinds of sheet material are more susceptible to wrinkling, spring back and fracture during press shop operations. For characterization of capability of sheet material dedicated to deep drawing processes in the automotive industry, mainly Forming Limit Diagrams (FLD) are used. However, new investigations at the Institute for Metal Forming Technology have shown that High Strength Steel Sheet Material and Aluminum Alloys show increased formability in case of bending loads are superposed to stretching loads. Likewise, by superposing shearing on in plane uniaxial or biaxial tension formability changes because of materials crystallographic texture. Such mixed stress and strain conditions including bending and shearing effects can occur in deep-drawing processes of complex car body parts as well as subsequent forming operations like flanging. But changes in formability cannot be described by using the conventional FLC. Hence, for purpose of improvement of failure prediction in numerical simulation codes significant failure criteria for these strain conditions are missing. Considering such aspects in defining suitable failure criteria which is easy to implement into FEA a new semi-empirical model has been developed considering the effect of bending and shearing in sheet metals formability. This failure criterion consists of the combination of the so called cFLC (combined Forming Limit Curve), which considers superposed bending load conditions and the SFLC (Shear Forming Limit Curve), which again includes the effect of shearing on sheet metal's formability.

Application Of A New Semi-Empirical Model For Forming Limit Prediction Of Sheet Material Including Superposed Loads Of Bending And Shearing

International Nuclear Information System (INIS)

Held, Christian; Liewald, Mathias; Schleich, Ralf; Sindel, Manfred

2010-01-01

The use of lightweight materials offers substantial strength and weight advantages in car body design. Unfortunately such kinds of sheet material are more susceptible to wrinkling, spring back and fracture during press shop operations. For characterization of capability of sheet material dedicated to deep drawing processes in the automotive industry, mainly Forming Limit Diagrams (FLD) are used. However, new investigations at the Institute for Metal Forming Technology have shown that High Strength Steel Sheet Material and Aluminum Alloys show increased formability in case of bending loads are superposed to stretching loads. Likewise, by superposing shearing on in plane uniaxial or biaxial tension formability changes because of materials crystallographic texture. Such mixed stress and strain conditions including bending and shearing effects can occur in deep-drawing processes of complex car body parts as well as subsequent forming operations like flanging. But changes in formability cannot be described by using the conventional FLC. Hence, for purpose of improvement of failure prediction in numerical simulation codes significant failure criteria for these strain conditions are missing. Considering such aspects in defining suitable failure criteria which is easy to implement into FEA a new semi-empirical model has been developed considering the effect of bending and shearing in sheet metals formability. This failure criterion consists of the combination of the so called cFLC (combined Forming Limit Curve), which considers superposed bending load conditions and the SFLC (Shear Forming Limit Curve), which again includes the effect of shearing on sheet metal's formability.

Studying constructions of national identity across historical settings

DEFF Research Database (Denmark)

Ydesen, Christian; Øland, Trine

2018-01-01

, and national self-imagery. The first setting is the first decade after World War II and the second setting is the post-9/11 era. The empirical focus is based on sources pertaining to the way police officers and related professionals of the Danish welfare nation-state construct disturbing behavior and how......This article aims to demonstrate how constructions of national identity can be studied across historical settings. In this sense, the article contributes knowledge about how Danish-ness is constructed in two historical settings characterized by great upheavals in popular moral codes, culture...... these constructions are made into categories that activate an array of interventions. Using a comparative outlook between the two historical settings and by putting theoretically guided questions to work empirically, the purpose of this article is to understand 1) the boundaries of legitimate behavior and membership...

Measurement of two-particle semi-inclusive rapidity distributions at the CERN ISR

CERN Document Server

Amendolia, S R; Bosisio, L; Braccini, Pier Luigi; Bradaschia, C; Castaldi, R; Cavasinni, V; Cerri, C; Del Prete, T; Finocchiaro, G; Foà, L; Giromini, P; Grannis, P; Green, D; Jöstlein, H; Kephart, R; Laurelli, P; Menzione, A; Ristori, L; Sanguinetti, G; Thun, R; Valdata, M

1976-01-01

Data are presented on the semi-inclusive distributions of rapidities of secondary particles produced in pp collisions at very high energies. The experiment was performed at the CERN Intersecting Storage Rings (ISR). The data given, at centre-of-mass energies of square root s=23 and 62 GeV, include the single-particle distributions and two-particle correlations. The semi-inclusive correlations show pronounced short-range correlation effects which have a width considerably narrower than in the case of inclusive correlations. It is shown that these short-range effects can be understood empirically in terms of three parameters whose energy and multiplicity dependence are studied. The data support the picture of multiparticle production in which clusters of small multiplicity and small dispersion are emitted with subsequent decay into hadrons. (32 refs).

Vector magnetic fields in sunspots. I - Stokes profile analysis using the Marshall Space Flight Center magnetograph

Science.gov (United States)

Balasubramaniam, K. S.; West, E. A.

1991-01-01

The Marshall Space Flight Center (MSFC) vector magnetograph is a tunable filter magnetograph with a bandpass of 125 mA. Results are presented of the inversion of Stokes polarization profiles observed with the MSFC vector magnetograph centered on a sunspot to recover the vector magnetic field parameters and thermodynamic parameters of the spectral line forming region using the Fe I 5250.2 A spectral line using a nonlinear least-squares fitting technique. As a preliminary investigation, it is also shown that the recovered thermodynamic parameters could be better understood if the fitted parameters like Doppler width, opacity ratio, and damping constant were broken down into more basic quantities like temperature, microturbulent velocity, or density parameter.

Semi-Local DFT Functionals with Exact-Exchange-Like Features: Beyond the AK13

Science.gov (United States)

Armiento, Rickard

The Armiento-Kümmel functional from 2013 (AK13) is a non-empirical semi-local exchange functional on generalized gradient approximation form (GGA) in Kohn-Sham (KS) density functional theory (DFT). Recent works have established that AK13 gives improved electronic-structure exchange features over other semi-local methods, with a qualitatively improved orbital description and band structure. For example, the Kohn-Sham band gap is greatly extended, as it is for exact exchange. This talk outlines recent efforts towards new exchange-correlation functionals based on, and extending, the AK13 design ideas. The aim is to improve the quantitative accuracy, the description of energetics, and to address other issues found with the original formulation. Swedish e-Science Research Centre (SeRC).

Opportunities and barriers to straw construction

DEFF Research Database (Denmark)

White, Caroline Meyer; Howard, Thomas J.; Lenau, Torben Anker

2012-01-01

produced to support communication between clients and the consultants and facilitate the straw build design and decision making process. The intended audiences for the design guide are clients of small scale construction projects, architects, engineers, builders of straw construction, homeowner...... construction, and a series of qualitative interviews with a variety of stakeholders from previous straw build housing projects, results were gathered to find the most influential motives, barriers and considerations for straw build housing construction. Based on this empirical data, a design guide has been...

Semi-doubled sigma models for five-branes

International Nuclear Information System (INIS)

Kimura, Tetsuji

2016-01-01

We study two-dimensional N=(2,2) gauge theory and its dualized system in terms of complex (linear) superfields and their alternatives. Although this technique itself is not new, we can obtain a new model, the so-called “semi-doubled” GLSM. Similar to doubled sigma model, this involves both the original and dual degrees of freedom simultaneously, whilst the latter only contribute to the system via topological interactions. Applying this to the N=(4,4) GLSM for H-monopoles, i.e., smeared NS5-branes, we obtain its T-dualized systems in quite an easy way. As a bonus, we also obtain the semi-doubled GLSM for an exotic 5_2"3-brane whose background is locally nongeometric. In the low energy limit, we construct the semi-doubled NLSM which also generates the conventional string worldsheet sigma models. In the case of the NLSM for 5_2"3-brane, however, we find that the Dirac monopole equation does not make sense any more because the physical information is absorbed into the divergent part via the smearing procedure. This is nothing but the signal which indicates that the nongeometric feature emerges in the considering model.

A Model of Solid Waste Management Based Multilateral Co-Operation in Semi-Urban Community

Science.gov (United States)

Kanchanabhandhu, Chanchai; Woraphong, Seree

2016-01-01

The purpose of this research was to construct a model of solid waste management based on multilateral cooperation in semi-urban community. Its specific objectives were to 1) study the solid waste situation and involvement of community in the solid waste management in Wangtaku Sub-district, Muang District, Nakhon Pathom Province; 2) construct a…

Semi-empirical model for optimising future heavy-ion luminosity of the LHC

CERN Document Server

Schaumann, M

2014-01-01

The wide spectrum of intensities and emittances imprinted on the LHC Pb bunches during the accumulation of bunch trains in the injector chain result in a significant spread in the single bunch luminosities and lifetimes in collision. Based on the data collected in the 2011 Pb-Pb run, an empirical model is derived to predict the single-bunch peak luminosity depending on the bunch’s position within the beam. In combination with this model, simulations of representative bunches are used to estimate the luminosity evolution for the complete ensemble of bunches. Several options are being considered to improve the injector performance and to increase the number of bunches in the LHC, leading to several potential injection scenarios, resulting in different peak and integrated luminosities. The most important options for after the long shutdown (LS) 1 and 2 are evaluated and compared.

Combining Empirical and Stochastic Models for Extreme Floods Estimation

Science.gov (United States)

Zemzami, M.; Benaabidate, L.

2013-12-01

Hydrological models can be defined as physical, mathematical or empirical. The latter class uses mathematical equations independent of the physical processes involved in the hydrological system. The linear regression and Gradex (Gradient of Extreme values) are classic examples of empirical models. However, conventional empirical models are still used as a tool for hydrological analysis by probabilistic approaches. In many regions in the world, watersheds are not gauged. This is true even in developed countries where the gauging network has continued to decline as a result of the lack of human and financial resources. Indeed, the obvious lack of data in these watersheds makes it impossible to apply some basic empirical models for daily forecast. So we had to find a combination of rainfall-runoff models in which it would be possible to create our own data and use them to estimate the flow. The estimated design floods would be a good choice to illustrate the difficulties facing the hydrologist for the construction of a standard empirical model in basins where hydrological information is rare. The construction of the climate-hydrological model, which is based on frequency analysis, was established to estimate the design flood in the Anseghmir catchments, Morocco. The choice of using this complex model returns to its ability to be applied in watersheds where hydrological information is not sufficient. It was found that this method is a powerful tool for estimating the design flood of the watershed and also other hydrological elements (runoff, volumes of water...).The hydrographic characteristics and climatic parameters were used to estimate the runoff, water volumes and design flood for different return periods.

Methods for Calculating Empires in Quasicrystals

Directory of Open Access Journals (Sweden)

Fang Fang

2017-10-01

Full Text Available This paper reviews the empire problem for quasiperiodic tilings and the existing methods for generating the empires of the vertex configurations in quasicrystals, while introducing a new and more efficient method based on the cut-and-project technique. Using Penrose tiling as an example, this method finds the forced tiles with the restrictions in the high dimensional lattice (the mother lattice that can be cut-and-projected into the lower dimensional quasicrystal. We compare our method to the two existing methods, namely one method that uses the algorithm of the Fibonacci chain to force the Ammann bars in order to find the forced tiles of an empire and the method that follows the work of N.G. de Bruijn on constructing a Penrose tiling as the dual to a pentagrid. This new method is not only conceptually simple and clear, but it also allows us to calculate the empires of the vertex configurations in a defected quasicrystal by reversing the configuration of the quasicrystal to its higher dimensional lattice, where we then apply the restrictions. These advantages may provide a key guiding principle for phason dynamics and an important tool for self error-correction in quasicrystal growth.

Portfolio optimization of the construction sector companies in ...

African Journals Online (AJOL)

The objective of this paper is to construct the optimal portfolio that will minimize the portfolio risk and can achieve the investors target rate of return by using the mean-semi absolute deviation model. The data of this study comprises 20 construction sector companies that listed in Malaysia stock market from July 2011 until ...

Semi-analytical Model for Estimating Absorption Coefficients of Optically Active Constituents in Coastal Waters

Science.gov (United States)

Wang, D.; Cui, Y.

2015-12-01

The objectives of this paper are to validate the applicability of a multi-band quasi-analytical algorithm (QAA) in retrieval absorption coefficients of optically active constituents in turbid coastal waters, and to further improve the model using a proposed semi-analytical model (SAA). The ap(531) and ag(531) semi-analytically derived using SAA model are quite different from the retrievals procedures of QAA model that ap(531) and ag(531) are semi-analytically derived from the empirical retrievals results of a(531) and a(551). The two models are calibrated and evaluated against datasets taken from 19 independent cruises in West Florida Shelf in 1999-2003, provided by SeaBASS. The results indicate that the SAA model produces a superior performance to QAA model in absorption retrieval. Using of the SAA model in retrieving absorption coefficients of optically active constituents from West Florida Shelf decreases the random uncertainty of estimation by >23.05% from the QAA model. This study demonstrates the potential of the SAA model in absorption coefficients of optically active constituents estimating even in turbid coastal waters. Keywords: Remote sensing; Coastal Water; Absorption Coefficient; Semi-analytical Model

Development of Specialization Scales for the MSPI: A Comparison of Empirical and Inductive Strategies

Science.gov (United States)

Porfeli, Erik J.; Richard, George V.; Savickas, Mark L.

2010-01-01

An empirical measurement model for interest inventory construction uses internal criteria whereas an inductive measurement model uses external criteria. The empirical and inductive measurement models are compared and contrasted and then two models are assessed through tests of the effectiveness and economy of scales for the Medical Specialty…

The conceptualization and empirical validation of website user satisfaction

NARCIS (Netherlands)

Moenaert, R.K.; Muylle, S.; Despontin, M.

2004-01-01

This article addresses the concern for effective web site design by means of the conceptualization and empirical validation of a web site user satisfaction construct. Based on IS success theory, hypermedia design theory, a qualitative exploratory pilot study, and a quantitative online critical

Empirical Descriptions of Criminal Sentencing Decision-Making

Directory of Open Access Journals (Sweden)

Rasmus H. Wandall

2014-05-01

Full Text Available The article addresses the widespread use of statistical causal modelling to describe criminal sentencing decision-making empirically in Scandinavia. The article describes the characteristics of this model, and on this basis discusses three aspects of sentencing decision-making that the model does not capture: 1 the role of law and legal structures in sentencing, 2 the processes of constructing law and facts as they occur in the processes of handling criminal cases, and 3 reflecting newer organisational changes to sentencing decision-making. The article argues for a stronger empirically based design of sentencing models and for a more balanced use of different social scientific methodologies and models of sentencing decision-making.

ENHANCEMENT OF A SUNSPOT LIGHT WALL WITH EXTERNAL DISTURBANCES

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuhong; Zhang, Jun [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Erdélyi, Robert, E-mail: shuhongyang@nao.cas.cn [Solar Physics and Space Plasma Research Centre, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

2016-12-20

Based on the Interface Region Imaging Spectrograph observations, we study the response of a solar sunspot light wall to external disturbances. A flare occurrence near the light wall caused material to erupt from the lower solar atmosphere into the corona. Some material falls back to the solar surface and hits the light bridge (i.e., the base of the light wall), then sudden brightenings appear at the wall base followed by the rise of wall top, leading to an increase of the wall height. Once the brightness of the wall base fades, the height of the light wall begins to decrease. Five hours later, another nearby flare takes place, and a bright channel is formed that extends from the flare toward the light bridge. Although no obvious material flow along the bright channel is found, some ejected material is conjectured to reach the light bridge. Subsequently, the wall base brightens and the wall height begins to increase again. Once more, when the brightness of the wall base decays, the wall top fluctuates to lower heights. We suggest, based on the observed cases, that the interaction of falling material and ejected flare material with the light wall results in the brightenings of wall base and causes the height of the light wall to increase. Our results reveal that the light wall can be not only powered by the linkage of p -mode from below the photosphere, but may also be enhanced by external disturbances, such as falling material.

Evidence of Construct Validity for Work Values

Science.gov (United States)

Leuty, Melanie E.; Hansen, Jo-Ida C.

2011-01-01

Despite the importance of work values in the process of career adjustment (Dawis, 2002), little empirical research has focused on articulating the domains represented within the construct of work values and the examination of evidence of validity for the construct has been limited. Furthermore, the larger number of work values measures has made it…

[Social participation in mental health: space of construction of citizenship, policy formulation and decision making].

Science.gov (United States)

Guimarães, José Maria Ximenes; Jorge, Maria Salete Bessa; Maia, Regina Claudia Furtado; de Oliveira, Lucia Conde; Morais, Ana Patrícia Pereira; Lima, Marcos Paulo de Oliveira; Assis, Marluce Maria Araújo; dos Santos, Adriano Maia

2010-07-01

The article approaches the comprehension of professionals that act in the mental health area about the movement of construction of social participation in the health system of Fortaleza, Ceará State. The methodology adopted is based upon qualitative approach. The study was developed with semi-structured interviews with 17 mental health professionals of the city above mentioned. The empirical data was analyzed through the technique of thematic content analysis, where it was identified three cores of analysis: social participation as space of citizenship and policy formulation; oriented to attention of collective needs; and decision taking. The study reveals that social participation represents a possibility of amplifying X the relations between the Civil Society and the State, which makes possible the social intervention in proposals of the health policies. It is highlighted the right to health linked to the consolidation of democracy in the attention to the needs and collective edification.

Psychological Vulnerability to Completed Suicide: A Review of Empirical Studies.

Science.gov (United States)

Conner, Kenneth R.; Duberstein, Paul R.; Conwell, Yeates; Seidlitz, Larry; Caine, Eric D.

2001-01-01

This article reviews empirical literature on psychological vulnerability to completed suicide. Five constructs have been consistently associated with completed suicide: impulsivity/aggression; depression; anxiety; hopelessness; and self-consciousness/social disengagement. Current knowledge of psychological vulnerability could inform social…

GMDH-Based Semi-Supervised Feature Selection for Electricity Load Classification Forecasting

Directory of Open Access Journals (Sweden)

Lintao Yang

2018-01-01

Full Text Available With the development of smart power grids, communication network technology and sensor technology, there has been an exponential growth in complex electricity load data. Irregular electricity load fluctuations caused by the weather and holiday factors disrupt the daily operation of the power companies. To deal with these challenges, this paper investigates a day-ahead electricity peak load interval forecasting problem. It transforms the conventional continuous forecasting problem into a novel interval forecasting problem, and then further converts the interval forecasting problem into the classification forecasting problem. In addition, an indicator system influencing the electricity load is established from three dimensions, namely the load series, calendar data, and weather data. A semi-supervised feature selection algorithm is proposed to address an electricity load classification forecasting issue based on the group method of data handling (GMDH technology. The proposed algorithm consists of three main stages: (1 training the basic classifier; (2 selectively marking the most suitable samples from the unclassified label data, and adding them to an initial training set; and (3 training the classification models on the final training set and classifying the test samples. An empirical analysis of electricity load dataset from four Chinese cities is conducted. Results show that the proposed model can address the electricity load classification forecasting problem more efficiently and effectively than the FW-Semi FS (forward semi-supervised feature selection and GMDH-U (GMDH-based semi-supervised feature selection for customer classification models.

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

Energy Technology Data Exchange (ETDEWEB)

Hegde, Ganesh, E-mail: ghegde@purdue.edu; Povolotskyi, Michael; Kubis, Tillmann; Klimeck, Gerhard, E-mail: gekco@purdue.edu [Network for Computational Nanotechnology (NCN), Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Boykin, Timothy [Department of Electrical and Computer Engineering, University of Alabama, Huntsville, Alabama (United States)

2014-03-28

Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

International Nuclear Information System (INIS)

Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Klimeck, Gerhard; Boykin, Timothy

2014-01-01

Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

Science.gov (United States)

Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy; Klimeck, Gerhard

2014-03-01

Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

Measurement and correlation study of silymarin solubility in supercritical carbon dioxide with and without a cosolvent using semi-empirical models and back-propagation artificial neural networks

Directory of Open Access Journals (Sweden)

Gang Yang

2017-09-01

Full Text Available The solubility data of compounds in supercritical fluids and the correlation between the experimental solubility data and predicted solubility data are crucial to the development of supercritical technologies. In the present work, the solubility data of silymarin (SM in both pure supercritical carbon dioxide (SCCO2 and SCCO2 with added cosolvent was measured at temperatures ranging from 308 to 338 K and pressures from 8 to 22 MPa. The experimental data were fit with three semi-empirical density-based models (Chrastil, Bartle and Mendez-Santiago and Teja models and a back-propagation artificial neural networks (BPANN model. Interaction parameters for the models were obtained and the percentage of average absolute relative deviation (AARD% in each calculation was determined. The correlation results were in good agreement with the experimental data. A comparison among the four models revealed that the experimental solubility data were more fit with the BPANN model with AARDs ranging from 1.14% to 2.15% for silymarin in pure SCCO2 and with added cosolvent. The results provide fundamental data for designing the extraction of SM or the preparation of its particle using SCCO2 techniques.

Consistent empirical physical formula construction for recoil energy distribution in HPGe detectors by using artificial neural networks

International Nuclear Information System (INIS)

Akkoyun, Serkan; Yildiz, Nihat

2012-01-01

The gamma-ray tracking technique is a highly efficient detection method in experimental nuclear structure physics. On the basis of this method, two gamma-ray tracking arrays, AGATA in Europe and GRETA in the USA, are currently being tested. The interactions of neutrons in these detectors lead to an unwanted background in the gamma-ray spectra. Thus, the interaction points of neutrons in these detectors have to be determined in the gamma-ray tracking process in order to improve photo-peak efficiencies and peak-to-total ratios of the gamma-ray peaks. In this paper, the recoil energy distributions of germanium nuclei due to inelastic scatterings of 1–5 MeV neutrons were first obtained by simulation experiments. Secondly, as a novel approach, for these highly nonlinear detector responses of recoiling germanium nuclei, consistent empirical physical formulas (EPFs) were constructed by appropriate feedforward neural networks (LFNNs). The LFNN-EPFs are of explicit mathematical functional form. Therefore, the LFNN-EPFs can be used to derive further physical functions which could be potentially relevant for the determination of neutron interactions in gamma-ray tracking process.

The potential and need for energy saving in standard family detached and semi-detached wooden houses in arctic Greenland

DEFF Research Database (Denmark)

Bjarløv, Søren Peter; Vladyková, Petra

2011-01-01

The paper gives an account of the potential and need for energy saving in standard family detached and semi-detached wooden houses in Greenland. It is based on studies of house construction compared with Building Regulation requirements and the spread of buildings over time. In the climatic...... conditions of Greenland, there is considerable potential for energy saving in houses due to their construction, shape and condition. To estimate the total potential for energy saving and thus reducing CO2 emissions, we carried out a detailed investigation of three typical standard semi-detached family houses...

Mass deformed world-sheet action of semi local vortices

Energy Technology Data Exchange (ETDEWEB)

Jiang, Yunguo [School of Space Science and Physics, Shandong University at Weihai,264209 Weihai (China); Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment,264209 Weihai (China)

2014-02-10

The mass deformed effective world-sheet theory of semi local vortices was constructed via the field theoretical method. By Euler-Lagrangian equations, the Ansatze for both the gauge field and the adjoint scalar were solved, this ensures that zero modes of vortices are minimal excitations of the system. Up to the 1/g{sup 2} order, all profiles are solved. The mass deformed effective action was obtained by integrating out the transverse plane of the vortex string. The effective theory interpolates between the local vortex and the lump. Respecting certain normalization conditions, the effective theory shows a Seiberg-like duality, which agrees with the result of the Kähler quotient construction.

Rheological behavior of semi-solid 7075 aluminum alloy at steady state

Directory of Open Access Journals (Sweden)

Li Yageng

2014-03-01

Full Text Available The further application of semi-solid processing lies in the in-depth fundamental study like rheological behavior. In this research, the apparent viscosity of the semi-solid slurry of 7075 alloy was measured using a Couette type viscometer. The effects of solid fraction and shearing rate on the apparent viscosity of this alloy were investigated under different processing conditions. It can be seen that the apparent viscosity increases with an increase in the solid fraction from 10% to 50% (temperature 620 篊 to 630 篊 at steady state. When the solid fraction was fixed, the apparent viscosity can be decreased by altering the shearing rate from 61.235 s-1 to 489.88 s-1 at steady state. An empirical equation that shows the effects of solid fraction and shearing rate on the apparent viscosity is fitted. The microstructure of quenched samples was examined to understand the alloy抯 rheological behavior.

Innovative quality management practices in the Dutch construction industry

NARCIS (Netherlands)

Bossink, B.A.G.

2002-01-01

Quality management practices do support the management of strategically important innoυation processes. This conclusion is based on empirical research in the Dutch construction industry. A large-scale innovative construction project is intensively studied during a three-year period. The quality

The topside ionosphere above Arecibo at equinox during sunspot maximum

International Nuclear Information System (INIS)

Bailey, G.J.

1980-01-01

The coupled time-dependent 0 + and H + continuity and momentum equations and 0 + , H + and electron heat balance equations are solved simultaneously within the L = 1.4 (Arecibo) magnetic flux tube between an altitude of 120 km and the equatorial plane. The results of the calculations are used in a study of the topside ionosphere above Arecibo at equinox during sunspot maximum. Magnetically quiet conditions are assumed. The results of the calculations show that the L = 1.4 magnetic flux tube becomes saturated from an arbitrary state within 2-3 days. During the day the ion content of the magnetic flux tube consists mainly of 0 + whereas 0 + and H + are both important during the night. There is an altitude region in the topside ionosphere during the day where ion-counterstreaming occurs with H + flowing downward and 0 + flowing upward. The conditions causing this ion-counterstreaming are discussed. There is a net chemical gain of H + at the higher altitudes. This H + diffuses both upwards and downwards whilst 0 + diffuses upwards from its solar e.u.v. production source which is most important at the lower altitudes. During the night the calculated 0 + and H + temperatures are very nearly equal whereas during the day there are occasions when the H + temperature exceeds the 0 - temperature by about 300 K. (author)

Performance evaluation of 3D vision-based semi-autonomous control method for assistive robotic manipulator.

Science.gov (United States)

Ka, Hyun W; Chung, Cheng-Shiu; Ding, Dan; James, Khara; Cooper, Rory

2018-02-01

We developed a 3D vision-based semi-autonomous control interface for assistive robotic manipulators. It was implemented based on one of the most popular commercially available assistive robotic manipulator combined with a low-cost depth-sensing camera mounted on the robot base. To perform a manipulation task with the 3D vision-based semi-autonomous control interface, a user starts operating with a manual control method available to him/her. When detecting objects within a set range, the control interface automatically stops the robot, and provides the user with possible manipulation options through audible text output, based on the detected object characteristics. Then, the system waits until the user states a voice command. Once the user command is given, the control interface drives the robot autonomously until the given command is completed. In the empirical evaluations conducted with human subjects from two different groups, it was shown that the semi-autonomous control can be used as an alternative control method to enable individuals with impaired motor control to more efficiently operate the robot arms by facilitating their fine motion control. The advantage of semi-autonomous control was not so obvious for the simple tasks. But, for the relatively complex real-life tasks, the 3D vision-based semi-autonomous control showed significantly faster performance. Implications for Rehabilitation A 3D vision-based semi-autonomous control interface will improve clinical practice by providing an alternative control method that is less demanding physically as well cognitively. A 3D vision-based semi-autonomous control provides the user with task specific intelligent semiautonomous manipulation assistances. A 3D vision-based semi-autonomous control gives the user the feeling that he or she is still in control at any moment. A 3D vision-based semi-autonomous control is compatible with different types of new and existing manual control methods for ARMs.

Calibration strategy for semi-quantitative direct gas analysis using inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Gerdes, Kirk; Carter, Kimberly E.

2011-01-01

A process is described by which an ICP-MS equipped with an Octopole Reaction System (ORS) is calibrated using liquid phase standards to facilitate direct analysis of gas phase samples. The instrument response to liquid phase standards is analyzed to produce empirical factors relating ion generation and transmission efficiencies to standard operating parameters. Empirical factors generated for liquid phase samples are then used to produce semi-quantitative analysis of both mixed liquid/gas samples and pure gas samples. The method developed is similar to the semi-quantitative analysis algorithms in the commercial software, which have here been expanded to include gas phase elements such as Xe and Kr. Equations for prediction of relative ionization efficiencies and isotopic transmission are developed for several combinations of plasma operating conditions, which allows adjustment of limited parameters between liquid and gas injection modes. In particular, the plasma temperature and electron density are calculated from comparison of experimental results to the predictions of the Saha equation. Comparisons between operating configurations are made to determine the robustness of the analysis to plasma conditions and instrument operating parameters. Using the methods described in this research, the elemental concentrations in a liquid standard containing 45 analytes and treated as an unknown sample were quantified accurately to ± 50% for most elements using 133 Cs as a single internal reference. The method is used to predict liquid phase mercury within 12% of the actual concentration and gas phase mercury within 28% of the actual concentration. The results verify that the calibration method facilitates accurate semi-quantitative, gas phase analysis of metal species with sufficient sensitivity to quantify metal concentrations lower than 1 ppb for many metallic analytes.

Porphyry of Russian Empires in Paris

Science.gov (United States)

Bulakh, Andrey

2014-05-01

Porphyry of Russian Empires in Paris A. G. Bulakh (St Petersburg State University, Russia) So called "Schokhan porphyry" from Lake Onega, Russia, belongs surely to stones of World cultural heritage. One can see this "porphyry" at facades of a lovely palace of Pavel I and in pedestal of the monument after Nicolas I in St Petersburg. There are many other cases of using this stone in Russia. In Paris, sarcophagus of Napoleon I Bonaparte is constructed of blocks of this stone. Really, it is Proterozoic quartzite. Geology situation, petrography and mineralogical characteristic will be reported too. Comparison with antique porphyre from the Egyptian Province of the Roma Empire is given. References: 1) A.G.Bulakh, N.B.Abakumova, J.V.Romanovsky. St Petersburg: a History in Stone. 2010. Print House of St Petersburg State University. 173 p.

The semantics-pragmatics interplay in a partonomic construction

DEFF Research Database (Denmark)

Jensen, Kim Ebensgaard

2014-01-01

The present article presents a corpus-illustrated description of the English expression the X itself which treats the expression as a grammatical construction, as defined in usage-based construction grammar (an entrenched semiotic routine in a speech community). Investigating the construction...... steps in the building of a hypothesis regarding the nature of the X itself– one which can be tested and refined in future corpus-based empirical usage-based linguistic research....

Identifying Similarities in Cognitive Subtest Functional Requirements: An Empirical Approach

Science.gov (United States)

Frisby, Craig L.; Parkin, Jason R.

2007-01-01

In the cognitive test interpretation literature, a Rational/Intuitive, Indirect Empirical, or Combined approach is typically used to construct conceptual taxonomies of the functional (behavioral) similarities between subtests. To address shortcomings of these approaches, the functional requirements for 49 subtests from six individually…

Validation of Multilevel Constructs: Validation Methods and Empirical Findings for the EDI

Science.gov (United States)

Forer, Barry; Zumbo, Bruno D.

2011-01-01

The purposes of this paper are to highlight the foundations of multilevel construct validation, describe two methodological approaches and associated analytic techniques, and then apply these approaches and techniques to the multilevel construct validation of a widely-used school readiness measure called the Early Development Instrument (EDI;…

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. II. Application—Effect of quantum confinement and homogeneous strain on Cu conductance

Science.gov (United States)

Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Charles, James; Klimeck, Gerhard

2014-03-01

The Semi-Empirical tight binding model developed in Part I Hegde et al. [J. Appl. Phys. 115, 123703 (2014)] is applied to metal transport problems of current relevance in Part II. A systematic study of the effect of quantum confinement, transport orientation, and homogeneous strain on electronic transport properties of Cu is carried out. It is found that quantum confinement from bulk to nanowire boundary conditions leads to significant anisotropy in conductance of Cu along different transport orientations. Compressive homogeneous strain is found to reduce resistivity by increasing the density of conducting modes in Cu. The [110] transport orientation in Cu nanowires is found to be the most favorable for mitigating conductivity degradation since it shows least reduction in conductance with confinement and responds most favorably to compressive strain.

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. II. Application—Effect of quantum confinement and homogeneous strain on Cu conductance

International Nuclear Information System (INIS)

Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Charles, James; Klimeck, Gerhard

2014-01-01

The Semi-Empirical tight binding model developed in Part I Hegde et al. [J. Appl. Phys. 115, 123703 (2014)] is applied to metal transport problems of current relevance in Part II. A systematic study of the effect of quantum confinement, transport orientation, and homogeneous strain on electronic transport properties of Cu is carried out. It is found that quantum confinement from bulk to nanowire boundary conditions leads to significant anisotropy in conductance of Cu along different transport orientations. Compressive homogeneous strain is found to reduce resistivity by increasing the density of conducting modes in Cu. The [110] transport orientation in Cu nanowires is found to be the most favorable for mitigating conductivity degradation since it shows least reduction in conductance with confinement and responds most favorably to compressive strain

An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. II. Application—Effect of quantum confinement and homogeneous strain on Cu conductance

Energy Technology Data Exchange (ETDEWEB)

Hegde, Ganesh, E-mail: ghegde@purdue.edu; Povolotskyi, Michael; Kubis, Tillmann; Charles, James; Klimeck, Gerhard, E-mail: gekco@purdue.edu [Network for Computational Nanotechnology (NCN), Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2014-03-28

The Semi-Empirical tight binding model developed in Part I Hegde et al. [J. Appl. Phys. 115, 123703 (2014)] is applied to metal transport problems of current relevance in Part II. A systematic study of the effect of quantum confinement, transport orientation, and homogeneous strain on electronic transport properties of Cu is carried out. It is found that quantum confinement from bulk to nanowire boundary conditions leads to significant anisotropy in conductance of Cu along different transport orientations. Compressive homogeneous strain is found to reduce resistivity by increasing the density of conducting modes in Cu. The [110] transport orientation in Cu nanowires is found to be the most favorable for mitigating conductivity degradation since it shows least reduction in conductance with confinement and responds most favorably to compressive strain.

X-ray structure, semi-empirical MO calculations and π-electron delocalization of 1-cyanoacetyl-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1 H-pyrazoles

Science.gov (United States)

Martins, Marcos A. P.; Moreira, Dayse N.; Frizzo, Clarissa P.; Campos, Patrick T.; Longhi, Kelvis; Marzari, Mara R. B.; Zanatta, Nilo; Bonacorso, Helio G.

2010-04-01

The structure of three 1-cyanoacetyl-3-alkyl[aryl]-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1 H-pyrazoles ( 1- 3) has been determined by X-ray diffractometry. The 4,5-dihydro-1 H-pyrazole rings were obtained as almost planar structures showing RMS deviation at a range of 0.0196-0.0736 Å. The data demonstrate that the molecular packing is dependent on the substituent present in each molecule. In addition, a computational investigation using semi-empirical AM1 and RM1 methods was performed in order to investigate the correlation between experimental and calculated geometrical parameters. The data obtained suggest that the structural data furnished by the AM1 method is in better agreement with those experimentally determined for the above compounds. An analysis of the π-electron delocalization by HOMA calculations indicate that there is a hyperconjugation effect in the imine group toward to phenyl group at ring 3-position of compound 2, and that this resonance effect decrease in compounds 1 and 3. In addition, it was showed that bond N(1) and C(6) do not have an amide character. Thus, the O(6)-C(6)-N(1)-N(2)-C(3) fragment is not completely delocalized mainly due to the low π-electron delocalization in N(1)-N(2) bond for all compounds.

Observations of Running Penumbral Waves Emerging in a Sunspot

Science.gov (United States)

Priya, T. G.; Wenda, Cao; Jiangtao, Su; Jie, Chen; Xinjie, Mao; Yuanyong, Deng; Robert, Erdélyi

2018-01-01

We present results from the investigation of 5 minute umbral oscillations in a single-polarity sunspot of active region NOAA 12132. The spectra of TiO, Hα, and 304 Å are used for corresponding atmospheric heights from the photosphere to lower corona. Power spectrum analysis at the formation height of Hα – 0.6 Å to the Hα center resulted in the detection of 5 minute oscillation signals in intensity interpreted as running waves outside the umbral center, mostly with vertical magnetic field inclination >15°. A phase-speed filter is used to extract the running wave signals with speed v ph > 4 km s‑1, from the time series of Hα – 0.4 Å images, and found twenty-four 3 minute umbral oscillatory events in a duration of one hour. Interestingly, the initial emergence of the 3 minute umbral oscillatory events are noticed closer to or at umbral boundaries. These 3 minute umbral oscillatory events are observed for the first time as propagating from a fraction of preceding running penumbral waves (RPWs). These fractional wavefronts rapidly separate from RPWs and move toward the umbral center, wherein they expand radially outwards suggesting the beginning of a new umbral oscillatory event. We found that most of these umbral oscillatory events develop further into RPWs. We speculate that the waveguides of running waves are twisted in spiral structures and hence the wavefronts are first seen at high latitudes of umbral boundaries and later at lower latitudes of the umbral center.

A dynamo theory prediction for solar cycle 22: Sunspot number, radio flux, exospheric temperature, and total density at 400 km

Science.gov (United States)

Schatten, K. H.; Hedin, A. E.

1986-01-01

Using the dynamo theory method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

A dynamo theory prediction for solar cycle 22 - Sunspot number, radio flux, exospheric temperature, and total density at 400 km

Science.gov (United States)

Schatten, K. H.; Hedin, A. E.

1984-01-01

Using the 'dynamo theory' method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

EMPIRICAL RESEARCH ON THE CHARACTERISTICS OF CLUSTERS IN ROMANIA AND THE IMPACT ON THE ENTREPRENEURIAL ENVIRONMENT

Directory of Open Access Journals (Sweden)

Tudor NISTORESCU

2017-05-01

Full Text Available The present research focuses on the empirical study about the features of clusters in Romania and its impact on business environment. In the scientific approach we tested five research hypotheses which have been validated. Methodological framework included as main instruments: questionnaires, semi-structured interviews with persons who represent the clusters, studies reported in the specialized literature, studies conducted in other projects, examples of best practice from countries with advanced economies. Findings which emerged from our empirical research, as a result of processing of data collection from respondents, may be useful to persons who manage clusters and decision-making authorities at regional and even national level.

Solar wind and coronal structure near sunspot minimum - Pioneer and SMM observations from 1985-1987

Science.gov (United States)

Mihalov, J. D.; Barnes, A.; Hundhausen, A. J.; Smith, E. J.

1990-01-01

Changes in solar wind speed and magnetic polarity observed at the Pioneer spacecraft are discussed here in terms of the changing magnetic geometry implied by SMM coronagraph observations over the period 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations during this epoch show a systematic variation in coronal structure and the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet, and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum.

Measurement of Am-242 fission yields at the Lohengrin spectrometer; improvement and Benchmarking of the semi-empirical code GEF

International Nuclear Information System (INIS)

Amouroux, Charlotte

2014-01-01

The study of fission yields has a major impact on the characterization and understanding of the fission process and is mandatory for reactor applications. While the yields are known for the major actinides (U-235, Pu-239) in the thermal neutron-induced fission, only few measurements were performed on Am-242. Moreover, the two main data libraries do not agree among each other on the light peak. Am-241 and Am-242 are nuclei of interest for the MOX-fuel reactors and for the reduction of nuclear waste radiotoxicity using transmutation reactions. Thus, a campaign of precise measurement of the fission mass yields from the reaction Am-241(2n,f) was performed at the Lohengrin mass spectrometer (ILL, France) for both the light and the heavy peak. Forty-one masses were measured. Moreover, the measurement of the isotopic fission yields on the heavy peak by gamma-ray spectrometry led to the extraction of 20 independent isotopic yields. Our measurement was also meant to determine whether there is a difference in fission yields between the Am-242 isomeric state and its ground state as it exists in fission cross sections. The experimental method used to answer this question is based on the measurement a set of fission mass yields as a function of the ratio of Am-242gs to Am-242m fission rate. Results show that the mass yields are independent of the fission rate ratio. A future experimental campaign is proposed to observe a possible influence on the isomeric yields. The theoretical models are nowadays unable to predict the fission yields with enough accuracy and therefore we have to rely on experimental data and phenomenological models. The accuracy of the predictions of the semi empirical GEF fission model predictions makes it a useful tool for evaluation. This thesis also presents the physical content and part of the development of this model. Validation of the kinetic energy distributions, isomeric yields and fission yields predictions was performed. The extension of the GEF

Quality planning in Construction Project

Science.gov (United States)

Othman, I.; Shafiq, Nasir; Nuruddin, M. F.

2017-12-01

The purpose of this paper is to investigate deeper on the factors that contribute to the effectiveness of quality planning, identifying the common problems encountered in quality planning, practices and ways for improvements in quality planning for construction projects. This paper involves data collected from construction company representatives across Malaysia that are obtained through semi-structured interviews as well as questionnaire distributions. Results shows that design of experiments (average index: 4.61), inspection (average index: 4.45) and quality audit as well as other methods (average index: 4.26) rank first, second and third most important factors respectively.

Economic Growth and Transboundary Pollution in Europe. An Empirical Analysis

Energy Technology Data Exchange (ETDEWEB)

Ansuategi, A. [Ekonomi Analisiaren Oinarriak I Saila, Ekonomi Zientzien Fakultatea, Lehendakari Agirre Etorbidea, 83, 48015 Bilbao (Spain)

2003-10-01

The existing empirical evidence suggests that environmental Kuznets curves only exist for pollutants with semi-local and medium term impacts. Ansuategi and Perrings (2000) have considered the behavioral basis for the correlation observed between different spatial incidence of environmental degradation and the relation between economic growth and environmental quality. They show that self-interested planners following a Nash-type strategy tend to address environmental effects sequentially: addressing those with the most immediate costs first, and those whose costs are displaced in space later. This paper tests such behavioral basis in the context of sulphur dioxide emissions in Europe.

Economic Growth and Transboundary Pollution in Europe. An Empirical Analysis

International Nuclear Information System (INIS)

Ansuategi, A.

2003-01-01

The existing empirical evidence suggests that environmental Kuznets curves only exist for pollutants with semi-local and medium term impacts. Ansuategi and Perrings (2000) have considered the behavioral basis for the correlation observed between different spatial incidence of environmental degradation and the relation between economic growth and environmental quality. They show that self-interested planners following a Nash-type strategy tend to address environmental effects sequentially: addressing those with the most immediate costs first, and those whose costs are displaced in space later. This paper tests such behavioral basis in the context of sulphur dioxide emissions in Europe

CRITICAL EVENTS IN CONSTRUCTION PROCESS

DEFF Research Database (Denmark)

Jørgensen, Kirsten; Rasmussen, Grane Mikael Gregaard

2009-01-01

cause-effects of failures and defects in the construction industry by using an analytical approach (The bowtie model) which is developed in the accident research. Using this model clarifies the relationships within the chain of failures that causes critical events with undesirable consequences......Function failures, defects and poor communication are major problems in the construction industry. These failures and defects are caused by a row of critical events in the construction process. The purpose of this paper is to define “critical events” in the construction process and to investigate....... In this way the causes of failures and the relationships between various failures are rendered visible. A large construction site was observed from start to finish as the empirical element in the research. The research focuses on all kinds of critical events identified throughout every phase during...

Semi-supervised learning for ordinal Kernel Discriminant Analysis.

Science.gov (United States)

Pérez-Ortiz, M; Gutiérrez, P A; Carbonero-Ruz, M; Hervás-Martínez, C

2016-12-01

Ordinal classification considers those classification problems where the labels of the variable to predict follow a given order. Naturally, labelled data is scarce or difficult to obtain in this type of problems because, in many cases, ordinal labels are given by a user or expert (e.g. in recommendation systems). Firstly, this paper develops a new strategy for ordinal classification where both labelled and unlabelled data are used in the model construction step (a scheme which is referred to as semi-supervised learning). More specifically, the ordinal version of kernel discriminant learning is extended for this setting considering the neighbourhood information of unlabelled data, which is proposed to be computed in the feature space induced by the kernel function. Secondly, a new method for semi-supervised kernel learning is devised in the context of ordinal classification, which is combined with our developed classification strategy to optimise the kernel parameters. The experiments conducted compare 6 different approaches for semi-supervised learning in the context of ordinal classification in a battery of 30 datasets, showing (1) the good synergy of the ordinal version of discriminant analysis and the use of unlabelled data and (2) the advantage of computing distances in the feature space induced by the kernel function. Copyright © 2016 Elsevier Ltd. All rights reserved.

The SQL++ Query Language: Configurable, Unifying and Semi-structured

OpenAIRE

Ong, Kian Win; Papakonstantinou, Yannis; Vernoux, Romain

2014-01-01

NoSQL databases support semi-structured data, typically modeled as JSON. They also provide limited (but expanding) query languages. Their idiomatic, non-SQL language constructs, the many variations, and the lack of formal semantics inhibit deep understanding of the query languages, and also impede progress towards clean, powerful, declarative query languages. This paper specifies the syntax and semantics of SQL++, which is applicable to both JSON native stores and SQL databases. The SQL++ sem...

Semi-Autonomous Systems Laboratory

Data.gov (United States)

Federal Laboratory Consortium — VisionThe Semi-Autonomous Systems Lab focuses on developing a comprehensive framework for semi-autonomous coordination of networked robotic systems. Semi-autonomous...

Soil surface moisture estimation over a semi-arid region using ENVISAT ASAR radar data for soil evaporation evaluation

Directory of Open Access Journals (Sweden)

M. Zribi

2011-01-01

Full Text Available The present paper proposes a method for the evaluation of soil evaporation, using soil moisture estimations based on radar satellite measurements. We present firstly an approach for the estimation and monitoring of soil moisture in a semi-arid region in North Africa, using ENVISAT ASAR images, over two types of vegetation covers. The first mapping process is dedicated solely to the monitoring of moisture variability related to rainfall events, over areas in the "non-irrigated olive tree" class of land use. The developed approach is based on a simple linear relationship between soil moisture and the backscattered radar signal normalised at a reference incidence angle. The second process is proposed over wheat fields, using an analysis of moisture variability due to both rainfall and irrigation. A semi-empirical model, based on the water-cloud model for vegetation correction, is used to retrieve soil moisture from the radar signal. Moisture mapping is carried out over wheat fields, showing high variability between irrigated and non-irrigated wheat covers. This analysis is based on a large database, including both ENVISAT ASAR and simultaneously acquired ground-truth measurements (moisture, vegetation, roughness, during the 2008–2009 vegetation cycle. Finally, a semi-empirical approach is proposed in order to relate surface moisture to the difference between soil evaporation and the climate demand, as defined by the potential evaporation. Mapping of the soil evaporation is proposed.

Chromospheric Plasma Ejections in a Light Bridge of a Sunspot

Energy Technology Data Exchange (ETDEWEB)

Song, Donguk; Chae, Jongchul; Yang, Heesu; Cho, Kyuhyoun; Kwak, Hannah [Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Yurchyshyn, Vasyl [Big Bear Solar Observatory, New Jersey Institute of Technology, 40386 North Shore Lane, Big Bear City, CA 92314-9672 (United States); Lim, Eun-Kyung; Cho, Kyung-Suk, E-mail: dusong@astro.snu.ac.kr [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of)

2017-02-01

It is well-known that light bridges (LBs) inside a sunspot produce small-scale plasma ejections and transient brightenings in the chromosphere, but the nature and origin of such phenomena are still unclear. Utilizing the high-spatial and high-temporal resolution spectral data taken with the Fast Imaging Solar Spectrograph and the TiO 7057 Å broadband filter images installed at the 1.6 m New Solar Telescope of Big Bear Solar Observatory, we report arcsecond-scale chromospheric plasma ejections (1.″7) inside a LB. Interestingly, the ejections are found to be a manifestation of upwardly propagating shock waves as evidenced by the sawtooth patterns seen in the temporal-spectral plots of the Ca ii 8542 Å and H α intensities. We also found a fine-scale photospheric pattern (1″) diverging with a speed of about 2 km s{sup −1} two minutes before the plasma ejections, which seems to be a manifestation of magnetic flux emergence. As a response to the plasma ejections, the corona displayed small-scale transient brightenings. Based on our findings, we suggest that the shock waves can be excited by the local disturbance caused by magnetic reconnection between the emerging flux inside the LB and the adjacent umbral magnetic field. The disturbance generates slow-mode waves, which soon develop into shock waves, and manifest themselves as the arcsecond-scale plasma ejections. It also appears that the dissipation of mechanical energy in the shock waves can heat the local corona.

Chromospheric Plasma Ejections in a Light Bridge of a Sunspot

Science.gov (United States)

Song, Donguk; Chae, Jongchul; Yurchyshyn, Vasyl; Lim, Eun-Kyung; Cho, Kyung-Suk; Yang, Heesu; Cho, Kyuhyoun; Kwak, Hannah

2017-02-01

It is well-known that light bridges (LBs) inside a sunspot produce small-scale plasma ejections and transient brightenings in the chromosphere, but the nature and origin of such phenomena are still unclear. Utilizing the high-spatial and high-temporal resolution spectral data taken with the Fast Imaging Solar Spectrograph and the TiO 7057 Å broadband filter images installed at the 1.6 m New Solar Telescope of Big Bear Solar Observatory, we report arcsecond-scale chromospheric plasma ejections (1.″7) inside a LB. Interestingly, the ejections are found to be a manifestation of upwardly propagating shock waves as evidenced by the sawtooth patterns seen in the temporal-spectral plots of the Ca II 8542 Å and Hα intensities. We also found a fine-scale photospheric pattern (1″) diverging with a speed of about 2 km s-1 two minutes before the plasma ejections, which seems to be a manifestation of magnetic flux emergence. As a response to the plasma ejections, the corona displayed small-scale transient brightenings. Based on our findings, we suggest that the shock waves can be excited by the local disturbance caused by magnetic reconnection between the emerging flux inside the LB and the adjacent umbral magnetic field. The disturbance generates slow-mode waves, which soon develop into shock waves, and manifest themselves as the arcsecond-scale plasma ejections. It also appears that the dissipation of mechanical energy in the shock waves can heat the local corona.

Construction of an evaluation index system of water resources bearing capacity: An empirical study in Xi’an, China

Science.gov (United States)

Qu, X. E.; Zhang, L. L.

2017-08-01

In this paper, a comprehensive evaluation of the water resources bearing capacity of Xi’an is performed. By constructing a comprehensive evaluation index system of the water resources bearing capacity that included water resources, economy, society, and ecological environment, we empirically studied the dynamic change and regional differences of the water resources bearing capacities of Xi’an districts through the TOPSIS method (Technique for Order Preference by Similarity to an Ideal Solution). Results show that the water resources bearing capacity of Xi’an significantly increased over time, and the contributions of the subsystems from high to low are as follows: water resources subsystem, social subsystem, ecological subsystem, and economic subsystem. Furthermore, there are large differences between the water resources bearing capacities of the different districts in Xi’an. The water resources bearing capacities from high to low are urban areas, Huxian, Zhouzhi, Gaoling, and Lantian. Overall, the water resources bearing capacity of Xi’an is still at a the lower level, which is highly related to the scarcity of water resources, population pressure, insufficient water saving consciousness, irrational industrial structure, low water-use efficiency, and so on.

Managing Conflict in The Nigerian Construction Industry: A Study of ...

African Journals Online (AJOL)

The study investigated the causes of conflictin the Nigerian construction industry and, the strategies for managing them in terms of resolutions and prevention. A quantitative approach using questionnaire survey was adopted to empirically test the opinions of construction professionals on causes of conflicts and ...

Construction in Occupied Spaces

Directory of Open Access Journals (Sweden)

Ward Andrew E.

2017-06-01

Full Text Available Conducting construction activities in occupied environments presents a great challenge due to the additional logistical requirements and the presence of the building occupants. The aim of this research is to gather and evaluate the means and methods to successfully plan, manage, and execute construction activities in occupied spaces in an effort to provide consolidated industry tools and strategies for maintaining a schedule and minimizing the impact on the occupants. The methodology of the research utilizes an exploratory approach to gather qualitative data. The data was collected through interviews with industry professionals to identify industry best practices. The semi-structured interviews provided a platform for the documents, lessons learned, and the techniques and strategies used for occupied construction by the construction industry. The information obtained in the interview process identified six themes that are critical to achieving and maintaining quality in occupied construction. These themes of the schedule, cost, customer satisfaction, planning, fire/life safety and utilities, and contractor management are reviewed in detail, and the paper discusses how to manage each element. The analysis and extracted management techniques, procedures and strategies can be used by the construction industry for future projects by focusing on the critical aspects of occupied construction and the manner in which to succeed with it.

Construction in Occupied Spaces

Science.gov (United States)

Ward, Andrew E.; Azhar, Salman; Khalfan, Malik

2017-06-01

Conducting construction activities in occupied environments presents a great challenge due to the additional logistical requirements and the presence of the building occupants. The aim of this research is to gather and evaluate the means and methods to successfully plan, manage, and execute construction activities in occupied spaces in an effort to provide consolidated industry tools and strategies for maintaining a schedule and minimizing the impact on the occupants. The methodology of the research utilizes an exploratory approach to gather qualitative data. The data was collected through interviews with industry professionals to identify industry best practices. The semi-structured interviews provided a platform for the documents, lessons learned, and the techniques and strategies used for occupied construction by the construction industry. The information obtained in the interview process identified six themes that are critical to achieving and maintaining quality in occupied construction. These themes of the schedule, cost, customer satisfaction, planning, fire/life safety and utilities, and contractor management are reviewed in detail, and the paper discusses how to manage each element. The analysis and extracted management techniques, procedures and strategies can be used by the construction industry for future projects by focusing on the critical aspects of occupied construction and the manner in which to succeed with it.

CONSTRUCTING FEMINISTS MAPS OF GOIÂNIA CITY

OpenAIRE

Cabral, Talita

2018-01-01

The goal is to construct maps of feminists actions in Goiania(GO). The chosen methodology use stories of leadership, by means of semi structured interviews with thirteen feminists and the interactive mapping techniques.  Were mapped the places and routes considerate important in the woman fight.

Understanding sexual harassment using aggregate construct models.

Science.gov (United States)

Nye, Christopher D; Brummel, Bradley J; Drasgow, Fritz

2014-11-01

Sexual harassment has received a substantial amount of empirical attention over the past few decades, and this research has consistently shown that experiencing these behaviors has a detrimental effect on employees' well-being, job attitudes, and behaviors at work. However, these findings, and the conclusions that are drawn from them, make the implicit assumption that the empirical models used to examine sexual harassment are properly specified. This article presents evidence that properly specified aggregate construct models are more consistent with theoretical structures and definitions of sexual harassment and can result in different conclusions about the nomological network of harassment. Results from 3 large samples, 2 military and 1 from a civilian population, are used to illustrate the differences between aggregate construct and reflective indicator models of sexual harassment. These analyses suggested that the factor structure and the nomological network of sexual harassment differ when modeling harassment as an aggregate construct. The implications of these results for the continued study of sexual harassment are discussed. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Empirical reality, empirical causality, and the measurement problem

International Nuclear Information System (INIS)

d'Espagnat, B.

1987-01-01

Does physics describe anything that can meaningfully be called independent reality, or is it merely operational? Most physicists implicitly favor an intermediate standpoint, which takes quantum physics into account, but which nevertheless strongly holds fast to quite strictly realistic ideas about apparently obvious facts concerning the macro-objects. Part 1 of this article, which is a survey of recent measurement theories, shows that, when made explicit, the standpoint in question cannot be upheld. Part 2 brings forward a proposal for making minimal changes to this standpoint in such a way as to remove such objections. The empirical reality thus constructed is a notion that, to some extent, does ultimately refer to the human means of apprehension and of data processing. It nevertheless cannot be said that it reduces to a mere name just labelling a set of recipes that never fail. It is shown that their usual notion of macroscopic causality must be endowed with similar features

Business models of micro businesses: Empirical evidence from creative industries

Directory of Open Access Journals (Sweden)

Pfeifer Sanja

2017-01-01

Full Text Available Business model describes how a business identifies and creates value for customers and how it organizes itself to capture some of this value in a profitable manner. Previous studies of business models in creative industries have only recently identified the unresolved issues in this field of research. The main objective of this article is to analyse the structure and diversity of business models and to deduce how these components interact or change in the context of micro and small businesses in creative services such as advertising, architecture and design. The article uses a qualitative approach. Case studies and semi-structured, in-depth interviews with six owners/managers of micro businesses in Croatia provide rich data. Structural coding in data analysis has been performed manually. The qualitative analysis has indicative relevance for the assessment and comparison of business models, however, it provides insights into which components of business models seem to be consolidated and which seem to contribute to the diversity of business models in creative industries. The article contributes to the advancement of empirical evidence and conceptual constructs that might lead to more advanced methodological approaches and proposition of the core typologies or classifications of business models in creative industries. In addition, a more detailed mapping of different choices available in managing value creation, value capturing or value networking might be a valuable help for owners/managers who want to change or cross-fertilize their business models.

Construction of a photovoltaic cell based on the photoelectrochemistry of organic dyes at transparent semi-conducting electrodes. Final report

Energy Technology Data Exchange (ETDEWEB)

Nasielski, J; Kirsch-De Mesmaeker, A

1982-01-01

It is shown that the study of the photoelectrochemical mechanisms of different dye-reductant systems at transparent semi-conducting bubbling gas electrodes, coupled with a detailed analysis of the photovoltammetric curves, allows: a deeper insight into the operation principles of the corresponding dye photogalvanic cells; prediction of the parameters important for optimizing the cell operation; and working out of strategies for improving the cell output. In order to compare the behaviors of an adsorbed type dye (rhodamine-hydroquinone) with a solution type dye in a photogalvanic cell, the thionine-Fe/sup 2 +/ system was examined, including a detailed kinetic analysis of the photocurrents at the bubbling gas electrode as a function of several parameters. Photoelectrochemical mechanisms related to the sensitization and supersensitization in this system have thus been determined. Photoelectrochemical methods were applied to analyze other dye-reductant systems. The photoelectrochemisty of three triphenyl-methanes, methyl violet, crystal violet, and malachite green were examined at the bubbling gas electrode. These dyes produce photocurrents originating from the adsorbed molecules and behave very much like rhodamine. The photoelectrochemical behavior of the erythrosine-hydroquinone couple is also examined. For constructing photogalvanic cells, the CdS-on-SnO/sub 2/-cysteine system is found promising. (LEW)

Elastic crack-tip stress field in a semi-strip

Directory of Open Access Journals (Sweden)

Victor Reut

2018-04-01

Full Text Available In this article the plain elasticity problem for a semi-strip with a transverse crack is investigated in the different cases of the boundary conditions at the semi-strips end. Unlike many works dedicated to this subject, the fixed singularities in the singular integral equation�s kernel are considered. The integral transformations� method is applied by the generalized scheme to reduce the initial problem to a one-dimensional problem. The one-dimensional problem is formulated as the vector boundary value problem which is solved with the help of matrix differential calculations and Green�s matrix apparatus. The solution of the problem is reduced to the solving of the system of three singular integral equations. Depending on the conditions given on the short edge of the semi-strip, the constructed singular integral equation can have one, or two fixed singularities. A special method is applied to solve this equation in regard of the singularities existence. Hence the system of the singular integral equations (SSIE is solved with the help of the generalized method. The stress intensity factors (SIF are investigated for different lengths of crack. The novelty of this work is in the application of new approach allowing the consideration of the fixed singularities in the problem about a transverse crack in the elastic semi-strip. The comparison of the numerical results� accuracy during the usage of the different approaches to the solving of SSIE is worked out

Semi-supervised learning via regularized boosting working on multiple semi-supervised assumptions.

Science.gov (United States)

Chen, Ke; Wang, Shihai

2011-01-01

Semi-supervised learning concerns the problem of learning in the presence of labeled and unlabeled data. Several boosting algorithms have been extended to semi-supervised learning with various strategies. To our knowledge, however, none of them takes all three semi-supervised assumptions, i.e., smoothness, cluster, and manifold assumptions, together into account during boosting learning. In this paper, we propose a novel cost functional consisting of the margin cost on labeled data and the regularization penalty on unlabeled data based on three fundamental semi-supervised assumptions. Thus, minimizing our proposed cost functional with a greedy yet stagewise functional optimization procedure leads to a generic boosting framework for semi-supervised learning. Extensive experiments demonstrate that our algorithm yields favorite results for benchmark and real-world classification tasks in comparison to state-of-the-art semi-supervised learning algorithms, including newly developed boosting algorithms. Finally, we discuss relevant issues and relate our algorithm to the previous work.

Transfer of radionuclides by terrestrial food products from semi-natural ecosystems to humans

International Nuclear Information System (INIS)

Howard, B.J.

1996-01-01

The potential radiological significance of radionuclide transfer to humans via foodstuffs derived from semi-natural ecosystems has become apparent since the Chernobyl accident. Foodchain models developed before this time usually did not take such transfers into account. The processes leading to contamination of food in these environments are complex and current understanding of the transfer mechanisms is incomplete. For these reasons the approach adopted in Chapter 3 is to represent, by means of aggregated parameters, the empirical relationships between ground deposits and concentration in the food product. 107 refs, 2 figs, 9 tabs

The Socratic Method: Empirical Assessment of a Psychology Capstone Course

Science.gov (United States)

Burns, Lawrence R.; Stephenson, Paul L.; Bellamy, Katy

2016-01-01

Although students make some epistemological progress during college, most graduate without developing meaning-making strategies that reflect an understanding that knowledge is socially constructed. Using a pre-test-post-test design and a within-subjects 2 × 2 mixed-design ANOVA, this study reports on empirical findings which support the Socratic…

ConStruct: Improved construction of RNA consensus structures

Directory of Open Access Journals (Sweden)

Steger Gerhard

2008-04-01

Full Text Available Abstract Background Aligning homologous non-coding RNAs (ncRNAs correctly in terms of sequence and structure is an unresolved problem, due to both mathematical complexity and imperfect scoring functions. High quality alignments, however, are a prerequisite for most consensus structure prediction approaches, homology searches, and tools for phylogeny inference. Automatically created ncRNA alignments often need manual corrections, yet this manual refinement is tedious and error-prone. Results We present an extended version of CONSTRUCT, a semi-automatic, graphical tool suitable for creating RNA alignments correct in terms of both consensus sequence and consensus structure. To this purpose CONSTRUCT combines sequence alignment, thermodynamic data and various measures of covariation. One important feature is that the user is guided during the alignment correction step by a consensus dotplot, which displays all thermodynamically optimal base pairs and the corresponding covariation. Once the initial alignment is corrected, optimal and suboptimal secondary structures as well as tertiary interaction can be predicted. We demonstrate CONSTRUCT's ability to guide the user in correcting an initial alignment, and show an example for optimal secondary consensus structure prediction on very hard to align SECIS elements. Moreover we use CONSTRUCT to predict tertiary interactions from sequences of the internal ribosome entry site of CrP-like viruses. In addition we show that alignments specifically designed for benchmarking can be easily be optimized using CONSTRUCT, although they share very little sequence identity. Conclusion CONSTRUCT's graphical interface allows for an easy alignment correction based on and guided by predicted and known structural constraints. It combines several algorithms for prediction of secondary consensus structure and even tertiary interactions. The CONSTRUCT package can be downloaded from the URL listed in the Availability and

Issues engulfed Saudi Arabia construction workers

Science.gov (United States)

Al-Emad, N. H.; Rahman, I. A.

2018-04-01

This paper presents an exploratory study conducted in Makkah city to uncover issues faced by construction workers from the construction leaders’ perspective. Eleven construction leaders/experts were interviewed to unleash their experiences on handling the foreign workers working in Makkah construction projects. Most of the experts are senior management staffs with more than 10 years’ working experience in Saudi Arabia construction industry. The interviews were carried out in semi structured mode where all the information was captured manually and also electronically. The identified issues were sorted based on its commonality into 10 clusters. Hence in each cluster, the numbers of issue considered by the experts are reflecting the importance of that particular cluster. The result of the clusters according to the number of issues mentioned by the experts are safety issues, restricted government regulation, demotivated issues, lack of quality workers, poor living quality, communication barriers, adaption issues, poor attitudes, lack of logistical arrangements and lack of education. With these identified issues it will assist the construction players in the construction industry of Saudi Arabia in dealing with their workers.

Tools for Social Construction

DEFF Research Database (Denmark)

Brynskov, Martin

for social construction, i.e. supporting staging, performing, and sharing of playful activities involving people and artifacts.             The method used is a triangulation of the problem domain—pervasive media systems for children—from three perspectives: theory, design, and empirical work......: the potential of pervasive media systems to support the children’s social construction.  ......In this dissertation, I propose a new type of playful media for children. Based on field work, prototypes, and theoretical development, I define, build, and explore a distinct cross-section of existing and new digital media, tools, and communication devices in order to assess the characteristics...

Frames and semi-frames

International Nuclear Information System (INIS)

Antoine, Jean-Pierre; Balazs, Peter

2011-01-01

Loosely speaking, a semi-frame is a generalized frame for which one of the frame bounds is absent. More precisely, given a total sequence in a Hilbert space, we speak of an upper (resp. lower) semi-frame if only the upper (resp. lower) frame bound is valid. Equivalently, for an upper semi-frame, the frame operator is bounded, but has an unbounded inverse, whereas a lower semi-frame has an unbounded frame operator, with a bounded inverse. We study mostly upper semi-frames, both in the continuous and discrete case, and give some remarks for the dual situation. In particular, we show that reconstruction is still possible in certain cases.

Simulation of the honeycomb construction process

International Nuclear Information System (INIS)

Zhang Yuanzhang

2010-01-01

The construction process of the honeycomb by bees is an astonishing process. The original structure which the bees built is nothing more than a lot of rough cylinders. But keeping the beeswax semi-flow for a certain time, those rough structures become perfect hexahedral columns. A modified, simplified particle method was used here to simulate the semi-flow state of the material. Although the parameters used here were still rather subjective, the simulation still could demonstrate some behavior of that sort of material like beeswax. And the method that the bees used to build their honey comb, could be an efficient method to imitate when we are trying to manufacture cellular materials.

Calibration of semi-stochastic procedure for simulating high-frequency ground motions

Science.gov (United States)

Seyhan, Emel; Stewart, Jonathan P.; Graves, Robert

2013-01-01

Broadband ground motion simulation procedures typically utilize physics-based modeling at low frequencies, coupled with semi-stochastic procedures at high frequencies. The high-frequency procedure considered here combines deterministic Fourier amplitude spectra (dependent on source, path, and site models) with random phase. Previous work showed that high-frequency intensity measures from this simulation methodology attenuate faster with distance and have lower intra-event dispersion than in empirical equations. We address these issues by increasing crustal damping (Q) to reduce distance attenuation bias and by introducing random site-to-site variations to Fourier amplitudes using a lognormal standard deviation ranging from 0.45 for Mw  100 km).

A semi-empirical model for the prediction of fouling in railway ballast using GPR

Science.gov (United States)

Bianchini Ciampoli, Luca; Tosti, Fabio; Benedetto, Andrea; Alani, Amir M.; Loizos, Andreas; D'Amico, Fabrizio; Calvi, Alessandro

2016-04-01

The first step in the planning for a renewal of a railway network consists in gathering information, as effectively as possible, about the state of the railway tracks. Nowadays, this activity is mostly carried out by digging trenches at regular intervals along the whole network, to evaluate both geometrical and geotechnical properties of the railway track bed. This involves issues, mainly concerning the invasiveness of the operations, the impacts on the rail traffic, the high costs, and the low levels of significance concerning such discrete data set. Ground-penetrating radar (GPR) can represent a useful technique for overstepping these issues, as it can be directly mounted onto a train crossing the railway, and collect continuous information along the network. This study is aimed at defining an empirical model for the prediction of fouling in railway ballast, by using GPR. With this purpose, a thorough laboratory campaign was implemented within the facilities of Roma Tre University. In more details, a 1.47 m long × 1.47 m wide × 0.48 m height plexiglass framework, accounting for the domain of investigation, was laid over a perfect electric conductor, and filled up with several configuration of railway ballast and fouling material (clayey sand), thereby representing different levels of fouling. Then, the set of fouling configurations was surveyed with several GPR systems. In particular, a ground-coupled multi-channel radar (600 MHz and 1600 MHz center frequency antennas) and three air-launched radar systems (1000 MHz and 2000 MHz center frequency antennas) were employed for surveying the materials. By observing the results both in terms of time and frequency domains, interesting insights are highlighted and an empirical model, relating in particular the shape of the frequency spectrum of the signal and the percentage of fouling characterizing the surveyed material, is finally proposed. Acknowledgement The Authors thank COST, for funding the Action TU1208 "Civil

Fan-shaped jets above the light bridge of a sunspot driven by reconnection

Science.gov (United States)

Robustini, Carolina; Leenaarts, Jorrit; de la Cruz Rodriguez, Jaime; Rouppe van der Voort, Luc

2016-05-01

We report on a fan-shaped set of high-speed jets above a strongly magnetized light bridge (LB) of a sunspot observed in the Hα line. We study the origin, dynamics, and thermal properties of the jets using high-resolution imaging spectroscopy in Hα from the Swedish 1m Solar Telescope and data from the Solar Dynamics Observatory and Hinode. The Hα jets have lengths of 7-38 Mm, are impulsively accelerated to a speed of ~100 km s-1 close to photospheric footpoints in the LB, and exhibit a constant deceleration consistent with solar effective gravity. They are predominantly launched from one edge of the light bridge, and their footpoints appear bright in the Hα wings. Atmospheric Imaging Assembly data indicates elongated brightenings that are nearly co-spatial with the Hα jets. We interpret them as jets of transition region temperatures. The magnetic field in the light bridge has a strength of 0.8-2 kG and it is nearly horizontal. All jet properties are consistent with magnetic reconnection as the driver. Movies associated to Figs. 1 and 2 are available in electronic form at http://www.aanda.org

An empirical study of cultural evolution: the development of European cooking from medieval to modern times

Directory of Open Access Journals (Sweden)

Lindenfors, Patrik

2015-12-01

Full Text Available We have carried out an empirical study of long-term change in European cookery to test if the development of this cultural phenomenon matches a general hypothesis about cultural evolution: that human cultural change is characterized by cumulativity. Data from seven cookery books, evenly spaced across time, the oldest one written in medieval times (~1200 and the most recent one dating from late modernity (1999, were compared. Ten recipes from each of the categories “poultry recipes”, “fish recipes” and “meat recipes” were arbitrarily selected from each cookery book by selecting the first ten recipes in each category, and the numbers (per recipe of steps, separate partial processes, methods, ingredients, semi-manufactured ingredients, compound semi-manufactured ingredients (defined as semi-manufactured ingredients containing no less than two raw products, and self-made semi-manufactured ingredients were counted. Regression analyses were used to quantitatively compare the cookery from different ages. We found a significant increase in the numbers (per recipe of steps, separate partial processes, methods, ingredients and semi-manufactured ingredients. These significant increases enabled us to identify the development of cookery as an example of the general trend of cumulativity in long-term cultural evolution. The number of self-made semi-manufactured ingredients per recipe, however, may have decreased somewhat over time, something which may reflect the cumulative characteristics of cultural evolution at the level of society, considering the accumulation of knowledge that is required to industrialize food production.

Semi-metallic polymers

DEFF Research Database (Denmark)

Bubnova, Olga; Khan, Zia Ullah; Wang, Hui

2014-01-01

Polymers are lightweight, flexible, solution-processable materials that are promising for low-cost printed electronics as well as for mass-produced and large-area applications. Previous studies demonstrated that they can possess insulating, semiconducting or metallic properties; here we report...... that polymers can also be semi-metallic. Semi-metals, exemplified by bismuth, graphite and telluride alloys, have no energy bandgap and a very low density of states at the Fermi level. Furthermore, they typically have a higher Seebeck coefficient and lower thermal conductivities compared with metals, thus being...... a Fermi glass to a semi-metal. The high Seebeck value, the metallic conductivity at room temperature and the absence of unpaired electron spins makes polymer semi-metals attractive for thermoelectrics and spintronics....

Derivation of a semi-empirical formula for the quantum efficiency of forward secondary electron emission from γ-irradiated metals. 2

International Nuclear Information System (INIS)

Nakamura, Masamoto; Katoh, Yoh

1994-01-01

An empirical formula for the quantum efficiency of electrons irradiated with 60 Co γ-rays was reported in a previous paper, but its physical meaning was not made clear. Then, a simple model was assumed, from which a formula for calculating the efficiency was theoretically derived. Some parameters in the formula were determined so that the calculated results might fit the experimental data. The above empirical formula was shown to be the same as the formula physically derived this time. Results from the semiempirical formula and experimental data for Al and Pb sample were in agreement within the limits of 5%. (author)