Innovative Solar Tracking Concept by Rotating Prism Array

Directory of Open Access Journals (Sweden)

Héctor García

2014-01-01

Full Text Available Solar energy has become one of the most promising renewable energies and is the most widely used nowadays. In order to achieve an optimum performance, both photovoltaic and solar thermal applications are required to track the position of the sun throughout the day and year in the most effective way possible to avoid a high negative impact on the system efficiency. The present paper attempts to describe a novel semipassive solar tracking concentrator (SPSTC in which, in order to track the sun, two independent arrays of polymethyl methacrylate (PMMA prisms are implemented to refract sunlight by rotating said prisms, thus being able to redirect solar radiation as desired. The first set is responsible for eliminating one of the directional components of the solar radiation; the task is achieved by rotating the prisms within the array at a specific angle. The second set deals with another of the sunlight’s directional components, transforming its direction into a completely perpendicular pattern to the array. Having downward vertical radiation makes it possible to implement a stationary Fresnel lens to concentrate the solar radiation for any application desired. The system is designed and validated using simulation software to prove the feasibility of the concept.

Internal rotation of the Sun

International Nuclear Information System (INIS)

Duvall, T.L. Jr.; Goode, P.R.; Gouch, D.O.

1984-01-01

The frequency difference between prograde and retrograde sectoral solar oscillations is analysed to determine the rotation rate of the solar interior, assuming no latitudinal dependence. Much of the solar interior rotates slightly less rapidly than the surface, while the innermost part apparently rotates more rapidly. The resulting solar gravitational quadrupole moment is J 2 = (1.7 +- 0.4) x 10 -7 and provides a negligible contribution to current planetary tests of Einstein's theory of general relativity. (author)

Linear astrophysical dynamos in rotating spheres: Differential rotation, anisotropic turbulent magnetic diffusivity, and solar-stellar cycle magnetic parity

International Nuclear Information System (INIS)

Yoshimura, H.; Wang, Z.; Wu, F.

1984-01-01

Differential rotation dependence of the selection mechanism for magnetic parity of solar and stellar cycles is studied by assuming various differential rotation profiles inn the dynamo equation. The parity selection depends on propagation direction of oscillating magnetic fields in the form of dynamo waves which propagate along isorotation surfaces. When there is any radial gradient in the differential rotation, dynamo waves propagate either equatorward or poleward. In the former case, field systems of the two hemispheres approach each other and collide at the equator. Then, odd parity is selected. In the latter case, field systems of the two hemispheres recede from each other and do not collide at the equator, an even parity is selected. Thus the equatorial migration of wings of the butterfly iagram of the solar cycle and its odd parity are intrinsically related. In the case of purely latitudibnal differential rotation, dynamo waves propagate purely radially and growth rates of odd and even modes are nearly the same even when dynamo strength is weak when the parity selection mechanism should work most efficiently. In this case, anisotropy of turbulent diffusivity is a decisive factor to separate odd and even modes. Unlike in the case of radial-gradient-dominated differential rotation in which any difference between diffusivities for poloidal and toroidal fields enhancess the parity selection without changing the parity, the parity selection in the case of latitudinal-gradient-dominated differential rotation depends on the difference of diffusivities for poloidal and toroidal fields. When diffusivity for poloidal fields iss larger than that for toroidal fields, odd parity is selected; and when diffusivity for toroidal fields is larger, even parity is selected

M-number dependence of rotation period of the solar magnetic field and its effect on coronal hole and solar flare

International Nuclear Information System (INIS)

Saito, Takao; Oki, Tosio

1989-01-01

The photospheric magnetic field is revealed to rotate with different solar rotation periods depending on its m-number, or its longitudinal range. The m-dependent rotation reveals the unexplained solar cycle variation of the 28-day period of the IMF 2-sector structure in inclining/minimum years and of the 27-day period in the declining/minimum years. The m-dependent rotation reveals also the unexplained 155-day periodicity in the occurrence of solar flare clusters, suggesting a motion of the sunspot field relative to the large-scale field. The IMF sector structure is closely related to recurrent geomagnetic storms, while the flare occurrence is related to sporadic SC storms. Hence, the m-dependent rotation is quite important in the study of the STE forecast. (author)

Solar rotational cycle in lightning activity in Japan during the 18-19th centuries

Science.gov (United States)

Miyahara, Hiroko; Kataoka, Ryuho; Mikami, Takehiko; Zaiki, Masumi; Hirano, Junpei; Yoshimura, Minoru; Aono, Yasuyuki; Iwahashi, Kiyomi

2018-04-01

Thunderstorm and cloud activities sometimes show a 27-day period, and this has long been studied to uncover a possible important link to solar rotation. Because the 27-day variations in the solar forcing parameters such as solar ultraviolet and galactic cosmic rays become more prominent when the solar activity is high, it is expected that the signal of the 27-day period in meteorological phenomena may wax and wane according to the changes in the solar activity level. In this study, we examine in detail the intensity variations in the signal of the 27-day solar rotational period in thunder and lightning activity from the 18th to the 19th centuries based on 150-year-long records found in old diaries kept in Japan and discuss their relation with the solar activity levels. Such long records enable us to examine the signals of solar rotation at both high and low solar activity levels. We found that the signal of the solar rotational period in the thunder and lightning activity increases as the solar activity increases. In this study, we also discuss the possibility of the impact of the long-term climatological conditions on the signals of the 27-day period in thunder/lightning activities.

Rotation of the Solar Equator

Science.gov (United States)

Kotov, V. A.

2017-06-01

Regular measurements of the general magnetic field of the Sun, performed over about half a century at the Crimean Astrophysical Observatory, the J. Wilcox Solar Observatory, and five other observatories, are considered in detail for the time 1968 - 2016. They include more than twenty-six thousand daily values of the mean line-of-sight field strength of the visible solar hemisphere. On the basis of these values, the equatorial rotation period of the Sun is found to be 26.926(9) d (synodic). It is shown that its half-value coincides within error limits with both the main period of the magnetic four-sector structure, 13.4577(25) d, and the best-commensurate period of the slow motions of the major solar system bodies, 13.479(22) d (sidereal). The probability that the two periods coincide by chance is estimated to be about 10^{-7}. The true origin of this odd resonance is unknown.

The solar house that rotates

International Nuclear Information System (INIS)

Miloni, R.P.

2001-01-01

This article describes an innovative solar building in Weiz, Austria, that uses passive solar technologies, photovoltaics and a ground-coupled heat pump to cover its minimal energy requirements. The house, which follows the sun by rotating around its central axis, is described in detail, including its climatic design and its 'plus-energy' concept. Details are also given on the materials used in the house's construction and the functioning of its thermal insulation. The various operating modes of the house from the systems point of view are described for differing seasons and climatic extremes. Marketing aspects for this standardised house, featuring personal-computer-based on-line definition of facade cladding, fittings, photovoltaic power, furnishings etc. and real-time rendering of the house are also discussed

Solar Internal Rotation and Dynamo Waves: A Two Dimensional ...

Indian Academy of Sciences (India)

tribpo

Solar Internal Rotation and Dynamo Waves: A Two Dimensional. Asymptotic Solution in the Convection Zone ... We calculate here a spatial 2 D structure of the mean magnetic field, adopting real profiles of the solar internal ... of the asymptotic solution in low (middle) and high (right panel) latitudes. field is shifted towards the ...

Diagnostics of the solar corona from comparison between Faraday rotation measurements and magnetohydrodynamic simulations

International Nuclear Information System (INIS)

Le Chat, G.; Cohen, O.; Kasper, J. C.; Spangler, S. R.

2014-01-01

Polarized natural radio sources passing behind the Sun experience Faraday rotation as a consequence of the electron density and magnetic field strength in coronal plasma. Since Faraday rotation is proportional to the product of the density and the component of the magnetic field along the line of sight of the observer, a model is required to interpret the observations and infer coronal structures. Faraday rotation observations have been compared with relatively ad hoc models of the corona. Here for the first time we compare these observations with magnetohydrodynamic (MHD) models of the solar corona driven by measurements of the photospheric magnetic field. We use observations made with the NRAO Very Large Array of 34 polarized radio sources occulted by the solar corona between 5 and 14 solar radii. The measurements were made during 1997 May, and 2005 March and April. We compare the observed Faraday rotation values with values extracted from MHD steady-state simulations of the solar corona. We find that (1) using a synoptic map of the solar magnetic field just one Carrington rotation off produces poorer agreements, meaning that the outer corona changes in the course of one month, even in solar minimum; (2) global MHD models of the solar corona driven by photospheric magnetic field measurements are generally able to reproduce Faraday rotation observations; and (3) some sources show significant disagreement between the model and the observations, which appears to be a function of the proximity of the line of sight to the large-scale heliospheric current sheet.

SUN-LIKE MAGNETIC CYCLES IN THE RAPIDLY ROTATING YOUNG SOLAR ANALOG HD 30495

International Nuclear Information System (INIS)

Egeland, Ricky; Metcalfe, Travis S.; Hall, Jeffrey C.; Henry, Gregory W.

2015-01-01

A growing body of evidence suggests that multiple dynamo mechanisms can drive magnetic variability on different timescales, not only in the Sun but also in other stars. Many solar activity proxies exhibit a quasi-biennial (∼2 year) variation, which is superimposed upon the dominant 11 year cycle. A well-characterized stellar sample suggests at least two different relationships between rotation period and cycle period, with some stars exhibiting long and short cycles simultaneously. Within this sample, the solar cycle periods are typical of a more rapidly rotating star, implying that the Sun might be in a transitional state or that it has an unusual evolutionary history. In this work, we present new and archival observations of dual magnetic cycles in the young solar analog HD 30495, a ∼1 Gyr old G1.5 V star with a rotation period near 11 days. This star falls squarely on the relationships established by the broader stellar sample, with short-period variations at ∼1.7 years and a long cycle of ∼12 years. We measure three individual long-period cycles and find durations ranging from 9.6 to 15.5 years. We find the short-term variability to be intermittent, but present throughout the majority of the time series, though its occurrence and amplitude are uncorrelated with the longer cycle. These essentially solar-like variations occur in a Sun-like star with more rapid rotation, though surface differential rotation measurements leave open the possibility of a solar equivalence

Solar excitation of bicentennial Earth rotation oscillations

Czech Academy of Sciences Publication Activity Database

Ron, Cyril; Chapanov, Y.; Vondrák, Jan

2012-01-01

Roč. 9, č. 3 (2012), s. 259-268 ISSN 1214-9705 R&D Projects: GA ČR GA205/08/0908 Grant - others:Bulgarian NSF(BG) DO02-275; FP7(BG) MCA PIRSES-GA-2009-246874 Institutional support: RVO:67985815 Keywords : Earth rotation * solar activity Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.530, year: 2011

The structure of rotational discontinuities. [in solar wind

Science.gov (United States)

Neugebauer, M.

1989-01-01

This study examines the structures of a set of rotational discontinuities detected in the solar wind by the ISEE-3 spacecraft. It is found that the complexity of the structure increases as the angle theta between the propagation vector k and the magnetic field decreases. For rotational discontinuities that propagate at a large angle to the field with an ion (left-hand) sense of rotation, the magnetic hodograms tend to be flattened, in agreement with prior numerical simulations. When theta is large, angular 'overshoots' are often observed at one or both ends of the discontinuity. When the propagation is nearly parallel to the field (when theta is small), many different types of structure are seen, ranging from straight lines, to S-shaped curves, to complex, disorganized shapes.

Differential rotation and giant cell circulation of the solar Ca+-network

International Nuclear Information System (INIS)

Schroeter, E.H.; Woehl, H.

1976-01-01

High precision computer controlled tracings of bright Ca + -mottles were performed during 1974 and 1975 at the Locarno Observatory of Gottingen to study solar differential rotation and to search for giant cell circulation pattern. The method consists of measuring the position of 5-15 bright Ca + - mottles with respect to the center of the solar disc every 10 to 15 min during 4h every day. From a linear least square fit of the observed positions the solar-latitude and longitude were computed for the beginning and the end of the daily 4h observation period. From this the components in latitude and longitude of the proper motions were derived which result from the differential rotation, possible giant cell circulation and the small scale random walk of these features. (Auth.)

SOLAR ROTATION EFFECTS ON THE HELIOSHEATH FLOW NEAR SOLAR MINIMA

International Nuclear Information System (INIS)

Borovikov, Sergey N.; Pogorelov, Nikolai V.; Ebert, Robert W.

2012-01-01

The interaction between fast and slow solar wind (SW) due to the Sun's rotation creates corotating interaction regions (CIRs), which further interact with each other creating complex plasma structures at large heliospheric distances. We investigate the global influence of CIRs on the SW flow in the inner heliosheath between the heliospheric termination shock (TS) and the heliopause. The stream interaction model takes into account the major global effects due to slow-fast stream interaction near solar minima. The fast and slow wind parameters are derived from the Ulysses observations. We investigate the penetration of corotating structures through the TS and their further propagation through the heliosheath. It is shown that the heliosheath flow structure may experience substantial modifications, including local decreases in the radial velocity component observed by Voyager 1.

The zonal tidal effect on the variation in the rotation rate of the Earth with a fluid core I. Improvements on the theoretical formulae

Science.gov (United States)

Zhang, Han-Wei; Zheng, Yong; Du, Lan; Pan, Guan-Song

The tidal variation in Earth's rotation rate is a periodical response to solar-lunar tide generating potential (TGP). In this article, the factor of the fluid core, which is related with the variation in the polar moment of inertia of the Earth, is considered and introduced distinctly into the theoretical formula of the variation in the Earth's rotational rate caused by lunar-solar tide-producing force based on the dynamics principle of the fluid core Earth. Different from previously work, some Doodson developments are given including the variation formulae of the Earth's rotational rate, LOD and UT1. The reasons are pointed why the moment of inertia for the scale should be the effective polar rotational moment of inertia of the mantle and the Love number should be the effective Love number of the mantle. It is also indicated that the factor of the fluid core is consistent with the effect of the effective Love number of the mantle due to fluid core.

Seismology of rapidly rotating and solar-like stars

Science.gov (United States)

Reese, Daniel Roy

2018-05-01

A great deal of progress has been made in stellar physics thanks to asteroseismology, the study of pulsating stars. Indeed, asteroseismology is currently the only way to probe the internal structure of stars. The work presented here focuses on some of the theoretical aspects of this domain and addresses two broad categories of stars, namely solar-like pulsators (including red giants), and rapidly rotating pulsating stars. The work on solar-like pulsators focuses on setting up methods for efficiently characterising a large number of stars, in preparation for space missions like TESS and PLATO 2.0. In particular, the AIMS code applies an MCMC algorithm to find stellar properties and a sample of stellar models which fit a set of seismic and classic observational constraints. In order to reduce computation time, this code interpolates within a precalculated grid of models, using a Delaunay tessellation which allows a greater flexibility on the construction of the grid. Using interpolated models based on the outputs from this code or models from other forward modelling codes, it is possible to obtain refined estimates of various stellar properties such as the mean density thanks to inversion methods put together by me and G. Buldgen, my former PhD student. Finally, I show how inversion-type methods can also be used to test more qualitative information such as whether a decreasing rotation profile is compatible with a set of observed rotational splittings and a given reference model. In contrast to solar-like pulsators, the pulsation modes of rapidly rotating stars remain much more difficult to interpret due to the complexity of the numerical calculations needed to calculate such modes, the lack of simple frequency patterns, and the fact that it is difficult to predict mode amplitudes. The work described here therefore focuses on addressing the above difficulties one at a time in the hopes that it will one day be possible to carry out detailed asteroseismology in these

Consequences of high effective Prandtl number on solar differential rotation and convective velocity

Science.gov (United States)

Karak, Bidya Binay; Miesch, Mark; Bekki, Yuto

2018-04-01

Observations suggest that the large-scale convective velocities obtained by solar convection simulations might be over-estimated (convective conundrum). One plausible solution to this could be the small-scale dynamo which cannot be fully resolved by global simulations. The small-scale Lorentz force suppresses the convective motions and also the turbulent mixing of entropy between upflows and downflows, leading to a large effective Prandtl number (Pr). We explore this idea in three-dimensional global rotating convection simulations at different thermal conductivity (κ), i.e., at different Pr. In agreement with previous non-rotating simulations, the convective velocity is reduced with the increase of Pr as long as the thermal conductive flux is negligible. A subadiabatic layer is formed near the base of the convection zone due to continuous deposition of low entropy plumes in low-κ simulations. The most interesting result of our low-κ simulations is that the convective motions are accompanied by a change in the convection structure that is increasingly influenced by small-scale plumes. These plumes tend to transport angular momentum radially inward and thus establish an anti-solar differential rotation, in striking contrast to the solar rotation profile. If such low diffusive plumes, driven by the radiative-surface cooling, are present in the Sun, then our results cast doubt on the idea that a high effective Pr may be a viable solution to the solar convective conundrum. Our study also emphasizes that any resolution of the conundrum that relies on the downward plumes must take into account the angular momentum transport and heat transport.

Enstrophy-based proper orthogonal decomposition of flow past rotating cylinder at super-critical rotating rate

Science.gov (United States)

Sengupta, Tapan K.; Gullapalli, Atchyut

2016-11-01

Spinning cylinder rotating about its axis experiences a transverse force/lift, an account of this basic aerodynamic phenomenon is known as the Robins-Magnus effect in text books. Prandtl studied this flow by an inviscid irrotational model and postulated an upper limit of the lift experienced by the cylinder for a critical rotation rate. This non-dimensional rate is the ratio of oncoming free stream speed and the surface speed due to rotation. Prandtl predicted a maximum lift coefficient as CLmax = 4π for the critical rotation rate of two. In recent times, evidences show the violation of this upper limit, as in the experiments of Tokumaru and Dimotakis ["The lift of a cylinder executing rotary motions in a uniform flow," J. Fluid Mech. 255, 1-10 (1993)] and in the computed solution in Sengupta et al. ["Temporal flow instability for Magnus-robins effect at high rotation rates," J. Fluids Struct. 17, 941-953 (2003)]. In the latter reference, this was explained as the temporal instability affecting the flow at higher Reynolds number and rotation rates (>2). Here, we analyze the flow past a rotating cylinder at a super-critical rotation rate (=2.5) by the enstrophy-based proper orthogonal decomposition (POD) of direct simulation results. POD identifies the most energetic modes and helps flow field reconstruction by reduced number of modes. One of the motivations for the present study is to explain the shedding of puffs of vortices at low Reynolds number (Re = 60), for the high rotation rate, due to an instability originating in the vicinity of the cylinder, using the computed Navier-Stokes equation (NSE) from t = 0 to t = 300 following an impulsive start. This instability is also explained through the disturbance mechanical energy equation, which has been established earlier in Sengupta et al. ["Temporal flow instability for Magnus-robins effect at high rotation rates," J. Fluids Struct. 17, 941-953 (2003)].

Rotational Laser Cooling of MgH⁺ Ions and Rotational Rate Measurements

DEFF Research Database (Denmark)

Hansen, Anders Kragh; Staanum, Peter; Højbjerre, Klaus

by varying a delay between two such pairs of firings and measuring the yield of the second pair obtain the refilling rates. These rotational transition rate measurements are not only of direct interest for us to understand our rotational state preparation schemes, but will be important input to quantum...

An analysis of vibration-rotation lines of OH in the solar infrared spectrum

NARCIS (Netherlands)

Grevesse, N.; Sauval, A.J.; Dishoeck, van E.F.

1984-01-01

High resolution solar spectra have permitted the measurement with great accuracy of equivalent widths of vibration-rotation lines of OH in the X2Pi state near 3-micron wavelength. Using recent theoretical results for the transition probabilities, a solar oxygen abundance of (8.93 + or - 0.02) is

Optimum solar collector fluid flow rates

DEFF Research Database (Denmark)

Furbo, Simon; Shah, Louise Jivan

1996-01-01

Experiments showed that by means of a standard electronically controlled pump, type UPE 2000 from Grundfos it is possible to control the flow rate in a solar collector loop in such a way that the flow rate is strongly influenced by the temperature of the solar collector fluid passing the pump....... The flow rate is increasing for increasing temperature.The flow rate at the high temperature level is typically 70 % greater than the flow rate at the low temperature level.Further, the energy consumption for the electronically controlled pump in a solar heating system will be somewhat smaller than...... the energy consumption of a normal ciculation pump in the solar heating system.Calculations showed that the highest thermal performances for small SDHW systems based on mantle tanks with constant volume flow rates in the solar collector loops are achieved if the flow rate is situated in the interval from 0...

Solar activity, tidal friction and the earth rotation over the last 2000 years

International Nuclear Information System (INIS)

Kiselev, V.M.

1981-01-01

The tidal retardations of the Earth rotation and orbital motion of the Moon on Dynamical Time are discussed. The secular deceleration of the lunar motion deduced from an analysis of the anciept and medieval eclipses is lapger thap that obtained from recent (telescopic) observations. This discrepancy is shown to vanish if the Earth acceleration due to secular change of solar activity is taken into consideration. Therefore, one may suggest that the mean tidal friction has remained essentially constant over the last two millennia. Nontidal variations of the Earth rotation velocity in the historical past as well as at present time are shown to be caused by solar activity changes [ru

TIME-DEPENDENT NONEXTENSIVITY ARISING FROM THE ROTATIONAL EVOLUTION OF SOLAR-TYPE STARS

Energy Technology Data Exchange (ETDEWEB)

Silva, J. R. P.; Nepomuceno, M. M. F.; Soares, B. B.; De Freitas, D. B., E-mail: joseronaldo@uern.br [Departamento de Física, Universidade do Estado do Rio Grande do Norte, Mossoró-RN (Brazil)

2013-11-01

Nonextensive formalism is a generalization of the Boltzmann-Gibbs statistics. In this formalism, the entropic index q is a quantity characterizing the degree of nonextensivity and is interpreted as a parameter of long-memory or long-range interactions between the components of the system. Since its proposition in 1988, this formalism has been applied to investigate a wide variety of natural phenomena. In stellar astrophysics, a theoretical distribution function based on nonextensive formalism (q distributions) has been successfully applied to reproduce the distribution of stellar radial and rotational velocity data. In this paper, we investigate the time variation of the entropic index q obtained from the distribution of rotation, Vsin i, for a sample of 254 rotational data for solar-type stars from 11 open clusters aged between 35.5 Myr and 2.6 Gyr. As a result, we have found an anti-correlation between the entropic index q and the age of clusters, and that the distribution of rotation Vsin i for these stars becomes extensive for an age greater than about 170 Myr. Assuming that the parameter q is associated with long-memory effects, we suggest that the memory of the initial angular momentum of solar-type stars can be scaled by the entropic index q. We also propose a physical link between the parameter q and the magnetic braking of stellar rotation.

EVIDENCE FOR ROTATIONAL MOTIONS IN THE FEET OF A QUIESCENT SOLAR PROMINENCE

International Nuclear Information System (INIS)

Orozco Suárez, D.; Asensio Ramos, A.; Trujillo Bueno, J.

2012-01-01

We present observational evidence of apparent plasma rotational motions in the feet of a solar prominence. Our study is based on spectroscopic observations taken in the He I 1083.0 nm multiplet with the Tenerife Infrared Polarimeter attached to the German Vacuum Tower Telescope. We recorded a time sequence of spectra with 34 s cadence placing the slit of the spectrograph almost parallel to the solar limb and crossing two feet of an intermediate size, quiescent hedgerow prominence. The data show opposite Doppler shifts, ±6 km s –1 , at the edges of the prominence feet. We argue that these shifts may be interpreted as prominence plasma rotating counterclockwise around the vertical axis to the solar surface as viewed from above. The evolution of the prominence seen in EUV images taken with the Solar Dynamics Observatory provided us with clues to interpret the results as swirling motions. Moreover, time-distance images taken far from the central wavelength show plasma structures moving parallel to the solar limb with velocities of about 10-15 km s –1 . Finally, the shapes of the observed intensity profiles suggest the presence of, at least, two components at some locations at the edges of the prominence feet. One of them is typically Doppler shifted (up to ∼20 km s –1 ) with respect to the other, thus suggesting the existence of supersonic counter-streaming flows along the line of sight.

Effects of solar radiation pressure torque on the rotational motion of an artificial satellite

Science.gov (United States)

Zanardi, Maria Cecilia F. P. S.; Vilhenademoraes, Rodolpho

1992-01-01

The motion of an artificial satellite about its center of mass is studied considering torques due to the gravity gradient and direct solar radiation pressure. A model for direct solar radiation torque is derived for a circular cylindrical satellite. An analytical solution is obtained by the method of variation of the parameters. This solution shows that the angular variables have secular variation but that the modulus of the rotational angular momentum, the projection of rotational angular momentum on the z axis of the moment of inertia and inertial axis z, suffer only periodic variations. Considering a hypothetical artificial satellite, a numerical application is demonstrated.

A review of what numerical simulations tell us about the internal rotation of the sun

International Nuclear Information System (INIS)

Glatzmaier, G.A.

1986-01-01

The simulated solar differential rotation from two independent numerical modeling efforts agree with each other and with present solar observations. The models solve the nonlinear, three-dimensional, time-dependent, anelastic equations of motion for thermal convection in a stratified, rotating, spherical shell. The simulated angular velocity in the convection zone is constant on cylinders coaxial with the rotation axis, maximum at the equator and decreasing with depth. The latitudinal variation of this angular velocity at the surface is in agreement with Doppler measurements of the solar surface rotation rate. The radial variation through the convection zone is consistent with the analysis of the rotational frequency splitting of solar oscillations. 15 refs., 5 figs

Solar rotation effects on the thermospheres of Mars and Earth.

Science.gov (United States)

Forbes, Jeffrey M; Bruinsma, Sean; Lemoine, Frank G

2006-06-02

The responses of Earth's and Mars' thermospheres to the quasi-periodic (27-day) variation of solar flux due to solar rotation were measured contemporaneously, revealing that this response is twice as large for Earth as for Mars. Per typical 20-unit change in 10.7-centimeter radio flux (used as a proxy for extreme ultraviolet flux) reaching each planet, we found temperature changes of 42.0 +/- 8.0 kelvin and 19.2 +/- 3.6 kelvin for Earth and Mars, respectively. Existing data for Venus indicate values of 3.6 +/- 0.6 kelvin. Our observational result constrains comparative planetary thermosphere simulations and may help resolve existing uncertainties in thermal balance processes, particularly CO2 cooling.

Large scale circulation in the convection zone and solar differential rotation

Energy Technology Data Exchange (ETDEWEB)

Belvedere, G [Instituto di Astronomia dell' Universita di Catania, 95125 Italy; Paterno, L [Osservatorio Astrofisico di Catania, 95125 Italy

1976-04-01

In this paper the dependence on depth and latitude of the solar angular velocity produced by a meridian circulation in the convection zone is studied assuming that the main mechanism responsible for setting up and driving the circulation is the interaction of rotation with convection. The first order equations (perturbation of the spherically symmetric state are solved in the Boussinesq approximation and in the steady state for the axissymmetric case. The interaction of convection with rotation is modelled by a convective transport coefficient. The model is consistent with the fact that the interaction of convection with rotation sets up a circulation (driven by the temperature gradient) which carries angular momentum toward the equator against the viscous friction. Unfortunately also a large flux variation at the surface is obtained. Nevertheless it seems that the model has the basic requisites for correct dynamo action.

The various contributions in Venus rotation rate and LOD

Science.gov (United States)

Cottereau, L.; Rambaux, N.; Lebonnois, S.; Souchay, J.

2011-07-01

Context. Thanks to the Venus Express Mission, new data on the properties of Venus could be obtained, in particular concerning its rotation. Aims: In view of these upcoming results, the purpose of this paper is to determine and compare the major physical processes influencing the rotation of Venus and, more particularly, the angular rotation rate. Methods: Applying models already used for Earth, the effect of the triaxiality of a rigid Venus on its period of rotation are computed. Then the variations of Venus rotation caused by the elasticity, the atmosphere, and the core of the planet are evaluated. Results: Although the largest irregularities in the rotation rate of the Earth on short time scales are caused by its atmosphere and elastic deformations, we show that the irregularities for Venus are dominated by the tidal torque exerted by the Sun on its solid body. Indeed, as Venus has a slow rotation, these effects have a large amplitude of two minutes of time (mn). These variations in the rotation rate are greater than the one induced by atmospheric wind variations that can reach 25-50 s of time (s), depending on the simulation used. The variations due to the core effects that vary with its size between 3 and 20 s are smaller. Compared to these effects, the influence of the elastic deformation caused by the zonal tidal potential is negligible. Conclusions: As the variations in the rotation of Venus reported here are close to 3 mn peak to peak, they should influence past, present, and future observations, thereby providing further constraints on the planet's internal structure and atmosphere.

Role of Interaction between Magnetic Rossby Waves and Tachocline Differential Rotation in Producing Solar Seasons

Science.gov (United States)

Dikpati, Mausumi; McIntosh, Scott W.; Bothun, Gregory; Cally, Paul S.; Ghosh, Siddhartha S.; Gilman, Peter A.; Umurhan, Orkan M.

2018-02-01

We present a nonlinear magnetohydrodynamic shallow-water model for the solar tachocline (MHD-SWT) that generates quasi-periodic tachocline nonlinear oscillations (TNOs) that can be identified with the recently discovered solar “seasons.” We discuss the properties of the hydrodynamic and magnetohydrodynamic Rossby waves that interact with the differential rotation and toroidal fields to sustain these oscillations, which occur due to back-and-forth energy exchanges among potential, kinetic, and magnetic energies. We perform model simulations for a few years, for selected example cases, in both hydrodynamic and magnetohydrodynamic regimes and show that the TNOs are robust features of the MHD-SWT model, occurring with periods of 2–20 months. We find that in certain cases multiple unstable shallow-water modes govern the dynamics, and TNO periods vary with time. In hydrodynamically governed TNOs, the energy exchange mechanism is simple, occurring between the Rossby waves and differential rotation. But in MHD cases, energy exchange becomes much more complex, involving energy flow among six energy reservoirs by means of eight different energy conversion processes. For toroidal magnetic bands of 5 and 35 kG peak amplitudes, both placed at 45° latitude and oppositely directed in north and south hemispheres, we show that the energy transfers responsible for TNO, as well as westward phase propagation, are evident in synoptic maps of the flow, magnetic field, and tachocline top-surface deformations. Nonlinear mode–mode interaction is particularly dramatic in the strong-field case. We also find that the TNO period increases with a decrease in rotation rate, implying that the younger Sun had more frequent seasons.

SOLAR CYCLE VARIABILITY AND SURFACE DIFFERENTIAL ROTATION FROM Ca II K-LINE TIME SERIES DATA

Energy Technology Data Exchange (ETDEWEB)

Scargle, Jeffrey D.; Worden, Simon P. [NASA Ames Research Center, Moffett Field, CA, 94035 (United States); Keil, Stephen L. [National Solar Observatory, P.O. Box 57, Sunspot, NM 88349 (United States)

2013-07-01

Analysis of over 36 yr of time series data from the NSO/AFRL/Sac Peak K-line monitoring program elucidates 5 components of the variation of the 7 measured chromospheric parameters: (a) the solar cycle (period {approx} 11 yr), (b) quasi-periodic variations (periods {approx} 100 days), (c) a broadband stochastic process (wide range of periods), (d) rotational modulation, and (e) random observational errors, independent of (a)-(d). Correlation and power spectrum analyses elucidate periodic and aperiodic variation of these parameters. Time-frequency analysis illuminates periodic and quasi-periodic signals, details of frequency modulation due to differential rotation, and in particular elucidates the rather complex harmonic structure (a) and (b) at timescales in the range {approx}0.1-10 yr. These results using only full-disk data suggest that similar analyses will be useful for detecting and characterizing differential rotation in stars from stellar light curves such as those being produced by NASA's Kepler observatory. Component (c) consists of variations over a range of timescales, in the manner of a 1/f random process with a power-law slope index that varies in a systematic way. A time-dependent Wilson-Bappu effect appears to be present in the solar cycle variations (a), but not in the more rapid variations of the stochastic process (c). Component (d) characterizes differential rotation of the active regions. Component (e) is of course not characteristic of solar variability, but the fact that the observational errors are quite small greatly facilitates the analysis of the other components. The data analyzed in this paper can be found at the National Solar Observatory Web site http://nsosp.nso.edu/cak{sub m}on/, or by file transfer protocol at ftp://ftp.nso.edu/idl/cak.parameters.

On disturbances in the atmosphere produced by solar heating and by earth rotation

International Nuclear Information System (INIS)

Somsikov, V.M.

1980-01-01

Using solar terminator as an example analyzed are the problems connected with generation of various disturbances in atmosphere resulted from solar heating and earth rotation. An equation for atmosphere pressure disturbance in the spherical system of coordinates is obtained. The Green function of this equation is found for isothermal atmosphere. A spectrum of space harmonics of disturbances is found and its diagram is presented. It is shown that disturbances of large and small scales can arize in atmosphere simultaneously. They can be refferred to acoustic, gravitational and tidal waves. It is noted that the obtained equation solution permits to obtain a full spectrum of atmosphere vibrations, conditioned by its solar heating

Radar meteor rates and solar activity

International Nuclear Information System (INIS)

Prikryl, P.

1983-01-01

The short-term variation of diurnal radar meteor rates with solar activity represented by solar microwave flux Fsub(10.7), and sunspots relative number Rsub(z), is investigated. Applying the superposed-epoch analysis to the observational material of radar meteor rates from Christchurch (1960-61 and 1963-65), a decrease in the recorded radar rates is found during days of enhanced solar activity. No effect of geomagnetic activity similar to the one reported for the Swedish and Canadian radar meteor data was found by the author in the Christchurch data. A possible explanation of the absence of the geomagnetic effect on radar meteor rates from New Zealand due to a lower echo ceiling height of the Christchurch radar is suggested. The variation of the atmospheric parameters as a possible cause of the observed variation in radar meteor rates is also discussed. (author)

Rotational history of the sun: Spin-down of the interior by circulation currents and fluid instabilities

International Nuclear Information System (INIS)

Endal, A.S.; Sofia, S.

1980-01-01

A number of astronomical observations show that solar-type stars begin the main-sequence stage with surface rotation rates which are much greater than that of the sun. The subsequent decrease in the surface rotation rate is due to the braking torque exerted by magnetically-coupled mass loss (the solar wind). The direct braking action of the solar wind should be confined to the convective envelope so the rotation of the radiative interior remains an open question. After reviewing the relevant astronomical data, we describe how angular momentum could be transported out of the radiative interior by fluid instabilities and estimate the time scales for such transport. This picture is used to construct an evolutionary model of the sun, which predicts the present rotation of the radiative interior. The results of such a model are interpreted in terms of the measured oblateness of the solar surface

A new picture for the internal rotation of the sun

International Nuclear Information System (INIS)

Morrow, C.A.

1988-01-01

This thesis describes a helioseismic quest to determine the angular velocity inside the Sun as a function of depth and latitude. The author analyzes rotational frequency splittings extracted from 15 days of full-disk observations of the solar acoustic oscillations (1 = 15-99) obtained with the Fourier Tachometer (a Doppler analyzing instrument design by Tim Brown). She has compared the observed frequency splittings to those generated by several different physically-motivated models for the solar internal angular velocity. She also introduces convenient preliminary analysis techniques, which require no formal computations and which guide the choices of rotation models. He analysis suggests that the differential rotation in latitude observed at the solar surface pervades the convection zone and perhaps even deeper layers. Thus, the convection zone appears to contain little or no radial gradient of angular velocity. The analysis further indicates that the angular velocity of the outer portion of the radiative interior is constant, or nearly so, at a value that is intermediate between the relatively fast equatorial rate and the slower polar rate of the surface profile. This new picture of the Sun's internal rotation implies that a significant radial gradient exists only in a transitional layer between the convection zone and the radiative interior. This model has intriguing implications for the solar dynamo, for the current distribution and transport of angular momentum, and for the current distribution and transport of angular momentum, and for the rotational and evolutionary history of the Sun

Variations of the Earth's rotation rate and cyclic processes in geodynamics

Directory of Open Access Journals (Sweden)

B.W. Levin

2017-05-01

Full Text Available The authors analyzed the relationship between variations of the Earth's rotation rate and the geodynamic processes within the Earth's body, including seismic activity. The rotation rate of a planet determines its uniaxial compression along the axis of rotation and the areas of various surface elements of the body. The Earth's ellipticity variations, caused naturally by the rotation rate variations, are manifested in vertical components of precise GPS measurements. Comparative analysis of these variations is considered in view of modern theoretical ideas concerning the Earth's figure. The results justify further research that is of interest for improvement of space systems and technologies.

The zonal tidal effect on the variation in the rotation rate of the Earth with a fluid core II. Numerical calculation and comparisons

Science.gov (United States)

Zhang, Han-Wei; Zheng, Yong; Du, Lan; Pan, Guan-Song

The tidal variation in Earth rotation rate is a periodical response to solar-lunar tide generating potential (TGP). Some theoretical formulae are given here based on Doodson development of TGP including the variations in Earth rotation rate, LOD and UT1. Finally the zonal tidal effect on the variation in the fluid core Earth rotation rate is calculated according to the formula deduced by Xi Qinwen (1995). The calculation shows that the results in this paper are well consistent with the ones in IERS (96), which indicates the correctness of the theoretical formula we deduced. It is also shown that the effects from the high frequency parts are relatively small, within the observing precision so far; relatively large effects due to the lower parts, which should be able to be seperated from the observed data, are actually difficult to make because of the influence from some non-tidal factors as well as short time span data.

Resonant amplification of neutrino spin rotation in matter and the solar-neutrino problem

International Nuclear Information System (INIS)

Akhmedov, E.Kh.

1988-01-01

It is shown that in the presence of matter there can occur resonant amplification of the flavor-changing neutrino spin rotation in transverse magnetic fields, which is roughly analogous to the Mikheyev-Smirnov-Wolfenstein effect in neutrino oscillations. Possible consequences for solar neutrinos are briefly discussed. (orig.)

On a relation of geomagnetic activity, solar wind velocity and irregularity of daily rotation of the Earth

International Nuclear Information System (INIS)

Kalinin, Yu.D.; Kiselev, V.M.

1980-01-01

A possibility of the presence of statistic relation between the changes of the Earth rotation regime and the mean velocity of solar wind is discussed. The ratio between the solar wind velocity observed and planetary index of geomagnetic activity am is used to determine the annual average values of solar wind velocity beyond the twentieth cycle of solar activity. The restored changes of solar wind velocity are compared with solar conditioned variations of the Earth day duration and it is shown that the correspondence takes place only at frequencies lower the frequency of 11-year cycle [ru

Solar influence on meteor rates and atmospheric density variations at meteor heights

International Nuclear Information System (INIS)

Ellyett, C.

1977-01-01

A full analysis of radar-determined meteor rates from New Zealand, involving 3,085,574 meteors recorded over a total of 3 1/2 years, and 12,391,976 meteors recorded by the National Research Council of Canada in 8 1/2 years confirms an inverse relationship between meteor rates and solar activity as measured by sunspot numbers. The relationship, significant at the 1% level, appears in the Canadian annual average when the abnormal 1963 increase is removed, in monthly and 1/3-monthly results for the total Canadian period, and in monthly intervals for 1 year of the New Zealand data. This proven relationship of meteor rates with the solar cycle calls for a significant density gradient change over the solar cycle in the 70- to-120-km height range. Although some definite negative results have been reported, no unambiguous positive results are yet available supporting such a density gradient change. It is possible that density variations due to annual, semiannual, diurnal, and latitudinal changes obscure any 11-year density gradient change occurring at these heights. It is uncertain whether the 1963 increase represents density gradient changes in the meteor ablation region regularly brought about 1-2 years before each sunspot minimum or is a special event due to volcanic dust. The following additional facts have emerged from the present analysis. (1) Within a 1-year period the seasonal rate change of astronomical origin overrides any density gradient change in controlling the meteor rates in one of the two hemispheres. (2) The earth's daily rotation alters rates in phase with probable diurnal density gradient changes. (3) An effect due to D region absorption has been observed in the Canadian data

A Reuse Evaluation for Solar-Cell Silicon Wafers via Shift Revolution and Tool Rotation Using Magnetic Assistance in Ultrasonic Electrochemical Micromachining

Directory of Open Access Journals (Sweden)

P. S. Pa

2013-01-01

Full Text Available A new reuse fabrication using a tool module with rotation and revolution through a process of magnetic assistance in ultrasonic electrochemical micromachining (UEMM for removal of the surface layers from silicon wafers of solar cells is demonstrated. The target of the proposed reuse fabrication method is to replace the current approach, which uses strong acid and grinding and may damage the physical structure of silicon wafers and pollute to the environment. A precisely engineered clean production approach to removal of surface microstructure layers from silicon wafers is to develop a mass production system for recycling defective or discarded silicon wafers of solar cells that can reduce pollution and cost. The high revolution speed of the shift with the high rotation speed of the designed tool increases the discharge mobility and improves the removal effect associated with the high feed rate of the workpiece. High frequency and high power of ultrasonic with large electrolyte flow rate and high magnetic strengths with a small distance between the two magnets provide a large discharge effect and good removal; only a short period of time is required to remove the epoxy film and Si3N4 layer easily and cleanly.

Design of a deployment rotation mechanism for microsatellite

NARCIS (Netherlands)

Abdelal, G.F.; Bakr Elhady, A.; Kassab, M.

2009-01-01

Solar array rotation mechanism provides a hinged joint between the solar panel and satellite body, smooth rotation of the solar array into deployed position and its fixation in this position. After unlocking of solar panel (while in orbit), rotation bracket turns towards ready-to-work position under

Errors of car wheels rotation rate measurement using roller follower on test benches

Science.gov (United States)

Potapov, A. S.; Svirbutovich, O. A.; Krivtsov, S. N.

2018-03-01

The article deals with rotation rate measurement errors, which depend on the motor vehicle rate, on the roller, test benches. Monitoring of the vehicle performance under operating conditions is performed on roller test benches. Roller test benches are not flawless. They have some drawbacks affecting the accuracy of vehicle performance monitoring. Increase in basic velocity of the vehicle requires increase in accuracy of wheel rotation rate monitoring. It determines the degree of accuracy of mode identification for a wheel of the tested vehicle. To ensure measurement accuracy for rotation velocity of rollers is not an issue. The problem arises when measuring rotation velocity of a car wheel. The higher the rotation velocity of the wheel is, the lower the accuracy of measurement is. At present, wheel rotation frequency monitoring on roller test benches is carried out by following-up systems. Their sensors are rollers following wheel rotation. The rollers of the system are not kinematically linked to supporting rollers of the test bench. The roller follower is forced against the wheels of the tested vehicle by means of a spring-lever mechanism. Experience of the test bench equipment operation has shown that measurement accuracy is satisfactory at small rates of vehicles diagnosed on roller test benches. With a rising diagnostics rate, rotation velocity measurement errors occur in both braking and pulling modes because a roller spins about a tire tread. The paper shows oscillograms of changes in wheel rotation velocity and rotation velocity measurement system’s signals when testing a vehicle on roller test benches at specified rates.

Possible mechanism of the interplanetary medium effect on the diurnal rotation rate of the Earth

International Nuclear Information System (INIS)

Krymskij, P.F.

1993-01-01

Mechanism is proposed for effect of the solar wind and interplanetary magnetic field on the Earth rotation. In the mechanism base is Hall current generation in the plasma layer of the magnetosphere tail

The impact of changing solar screen rotation angle and its opening aspect ratios on Daylight Availability in residential desert buildings

KAUST Repository

Sherif, Ahmed H.; Sabry, Hanan M.; Gadelhak, Mahmoud I.

2012-01-01

usually used to diffuse and prevent direct solar penetration into spaces. This paper investigates the impact of changing solar screen axial rotation angle and screen opening aspect ratio on daylighting performance in a typical residential living room space

Decadal Cycles of Earth Rotation, Mean Sea Level and Climate, Excited by Solar Activity

Czech Academy of Sciences Publication Activity Database

Chapanov, Y.; Ron, Cyril; Vondrák, Jan

2017-01-01

Roč. 14, č. 2 (2017), s. 241-250 ISSN 1214-9705 R&D Projects: GA ČR GA13-15943S Institutional support: RVO:67985815 Keywords : Earth rotation * solar activity * mean sea level Subject RIV: DE - Earth Magnetism, Geodesy, Geography OBOR OECD: Physical geography Impact factor: 0.699, year: 2016

Photocatalytic degradation of aniline using an autonomous rotating drum reactor with both solar and UV-C artificial radiation.

Science.gov (United States)

Durán, A; Monteagudo, J M; San Martín, I; Merino, S

2018-03-15

The aim of this work was to evaluate the performance of a novel self-autonomous reactor technology (capable of working with solar irradiation and artificial UV light) for water treatment using aniline as model compound. This new reactor design overcomes the problems of the external mass transfer effect and the accessibility to photons occurring in traditional reaction systems. The UV-light source is located inside the rotating quartz drums (where TiO 2 is immobilized), allowing light to easily reach the water and the TiO 2 surface. Several processes (UV, H 2 O 2 , Solar, TiO 2 , Solar/TiO 2 , Solar/TiO 2 /H 2 O 2 and UV/Solar/H 2 O 2 /TiO 2 ) were tested. The synergy between Solar/H 2 O 2 and Solar/TiO 2 processes was quantified to be 40.3% using the pseudo-first-order degradation rate. The apparent photonic efficiency, ζ, was also determined for evaluating light utilization. For the Solar/TiO 2 /H 2 O 2 process, the efficiency was found to be practically constant (0.638-0.681%) when the film thickness is in the range of 1.67-3.87 μm. However, the efficiency increases up to 2.67% when artificial UV light was used in combination, confirming the efficient design of this installation. Thus, if needed, lamps can be switched on during cloudy days to improve the degradation rate of aniline and its mineralization. Under the optimal conditions selected for the Solar/TiO 2 /H 2 O 2 process ([H 2 O 2 ] = 250 mg/L; pH = 4, [TiO 2 ] = 0.65-1.25 mg/cm 2 ), 89.6% of aniline is degraded in 120 min. If the lamps are switched on, aniline is completely degraded in 10 min, reaching 85% of mineralization in 120 min. TiO 2 was re-used during 5 reaction cycles without apparent loss in activity (Solar/TiO 2 /H 2 O 2 process was found to have lower operation costs than other systems described in literature (0.67 €/m 3 ). Copyright © 2018 Elsevier Ltd. All rights reserved.

Helios-1 Faraday rotation experiment - Results and interpretations of the solar occultations in 1975

Science.gov (United States)

Volland, H.; Bird, M. K.; Levy, G. S.; Stelzried, C. T.; Seidel, B. L.

1977-01-01

The first of two solar occultations of the satellite Helios-1 in 1975 occurred in April when the satellite's ray path approached the west limb of the sun to a minimum distance of 1.63 solar radii. The second occultation took place in late August/early September when Helios-1 was totally eclipsed by the photosphere. Measurements of the polarization angle of the linearly polarized telemetry signal were performed with automatic tracking polarimeters at the 64 m Goldstone Tracking Station in California and also at the 100 m radio telescope in Effelsberg, West Germany. The coronal Faraday rotation as a function of the solar offset for both occultations is shown in graphs. The theoretical significance of the observations is investigated.

Helioseismic Solar Cycle Changes and Splitting Coefficients

Indian Academy of Sciences (India)

tribpo

Abstract. Using the GONG data for a period over four years, we have studied the variation of frequencies and splitting coefficients with solar cycle. Frequencies and even-order coefficients are found to change signi- ficantly with rising phase of the solar cycle. We also find temporal varia- tions in the rotation rate near the solar ...

A dissipative model of solar system and stability of stationary rotations

Science.gov (United States)

Vilke, V. G.

2009-04-01

In classical model of Solar system the planets are represented by the material points cooperating under the law of universal gravitation. This model remains fair if planet to consider as absolutely rigid spheres with spherical distribution of density. The gravitational potential of such body coincides with potential of a material point, and rotation of each sphere concerning his centre of mass occurs to constant angular velocity. The motion of the centers of mass of spherical planets identically to motion in the appropriate problem of points. Let's notice, that forms of planets of Solar system are close to spherical as dominant forces at formation of planets are gravitational forces to which forces of molecular interaction in substance of a planet counteract. The model of the isolated Solar system submitted in a not indignant condition by homogeneous viscoelastic spheres is considered. Under action of own rotation and tidal gravitational forces the spherical planet changes the shape: there is "flattening" of a planet in a direction of a vector of its angular velocity and formation of tidal bulgs on the lines connecting the centre of a planet with the centers of other planets. From a variational principle of Hamilton the full system of the equations describing movements of the centers of mass of planets, rotations of systems of coordinates, by integrated image connected with planets, and deformations of planets be relative these of systems of coordinates has been obtained. It is supposed, that tidal gravitational, centrifugal and elastic forces result in small change of the spherical form of a planet. In system there are small parameters - inversely proportional of the Young modules of materials of the planets, providing small deformations of planets at influence on them of the centrifugal forces produced by own rotation of planets, and the small tidal deformations arising under influence of gradients of gravitational forces. The method of division of movements

System and Method for Determining Rate of Rotation Using Brushless DC Motor

Science.gov (United States)

Howard, David E. (Inventor); Smith, Dennis A. (Inventor)

2000-01-01

A system and method are provided for measuring rate of rotation. A brushless DC motor is rotated and produces a back electromagnetic force (emf) on each winding thereof. Each winding's back-emf is squared. The squared outputs associated with each winding are combined, with the square root being taken of such combination, to produce a DC output proportional only to the rate of rotation of the motor's shaft.

Waldmeier's Rules in the Solar and Stellar Dynamos

Science.gov (United States)

Pipin, Valery; Kosovichev, Alexander

2015-08-01

The Waldmeier's rules [1] establish important empirical relations between the general parameters of magnetic cycles (such as the amplitude, period, growth rate and time profile) on the Sun and solar-type stars [2]. Variations of the magnetic cycle parameters depend on properties of the global dynamo processes operating in the stellar convection zones. We employ nonlinear mean-field axisymmetric dynamo models [3] and calculate of the magnetic cycle parameters, such as the dynamo cycle period, total magnetic and Poynting fluxes for the Sun and solar-type stars with rotational periods from 15 to 30 days. We consider two types of the dynamo models: 1) distributed (D-type) models employing the standard α - effect distributed in the whole convection zone, and 2) Babcock-Leighton (BL-type) models with a non-local α - effect. The dynamo models take into account the principal mechanisms of the nonlinear dynamo generation and saturation, including the magnetic helicity conservation, magnetic buoyancy effects, and the feedback on the angular momentum balance inside the convection zones. Both types of models show that the dynamo generated magnetic flux increases with the increase of the rotation rate. This corresponds to stronger brightness variations. The distributed dynamo model reproduces the observed dependence of the cycle period on the rotation rate for the Sun analogs better than the BL-type model. For the solar-type stars rotating more rapidly than the Sun we find dynamo regimes with multiple periods. Such stars with multiple cycles form a separate branch in the variability-rotation diagram.1. Waldmeier, M., Prognose für das nächste Sonnenfleckenmaximum, 1936, Astron. Nachrichten, 259,262. Soon,W.H., Baliunas,S.L., Zhang,Q.,An interpretation of cycle periods of stellar chromospheric activity, 1993, ApJ, 414,333. Pipin,V.V., Dependence of magnetic cycle parameters on period of rotation in nonlinear solar-type dynamos, 2015, astro-ph: 14125284

26Al yields from rotating Wolf--Rayet star models

OpenAIRE

Vuissoz, C.; Meynet, G.; Knoedlseder, J.; Cervino, M.; Schaerer, D.; Palacios, A.; Mowlavi, N.

2003-01-01

We present new $^{26}$Al stellar yields from rotating Wolf--Rayet stellar models which, at solar metallicity, well reproduce the observed properties of the Wolf-Rayet populations. These new yields are enhanced with respect to non--rotating models, even with respect to non--rotating models computed with enhanced mass loss rates. We briefly discuss some implications of the use of these new yields for estimating the global contribution of Wolf-Rayet stars to the quantity of $^{26}$Al now present...

Solar rotation and activity in the past and their possible influence upon the evolution of life

Energy Technology Data Exchange (ETDEWEB)

Geyer, E H

1980-01-01

Observations of enhanced spot active main sequence stars of solar type led to the formulation of the hypothesis which states that the rotational angular momentum, J/sub r/, of stars with spectral types later than F5 determines the intensity of their magnetic activity, bar A. Such very spot active stars are exclusively found as the components of fairly close binary stars, and show rotation periods smaller or more or less synchronous to the orbital period. Single stars of the lower main sequence are generally slow rotators, and do not show detectable activity in optical spectral regions, similar to the Sun if observed from stellar distances.

Faraday rotation fluctutation spectra observed during solar occultation of the Helios spacecraft

Science.gov (United States)

Andreev, V.; Efimov, A. I.; Samoznaev, L.; Bird, M. K.

1995-01-01

Faraday rotation (FR) measurements using linearly polarized radio signals from the two Helios spacecraft were carried out during the period from 1975 to 1984. This paper presents the results of a spectral analysis of the Helios S-band FR fluctuations observed at heliocentric distances from 2.6 to 15 solar radii during the superior conjunctions 1975-1983. The mean intensity of the FR fluctuations does not exceed the noise level for solar offsets greater than ca. 15 solar radii. The rms FR fluctuation amplitude increases rapidly as the radio ray path approaches the Sun, varying according to a power law (exponent: 2.85 +/- 0.15) at solar distances 4-12 solar radii. At distances inside 4 solar radii the increase is even steeper (exponent: 5.6 +/- 0.2). The equivalent two-dimensional FR fluctuation spectrum is well modeled by a single power-law over the frequency range from 5 to 50 mHz. For heliocentric distances larger than 4 solar radii the spectral index varies between 1.1 and 1.6 with a mean value of 1.4 +/- 0.2, corresponding to a 3-D spectral index p = 2.4. FR fluctuations thus display a somwhat lower spectral index compared with phase and amplitude fluctuations. Surprisingly high values of the spectral index were found for measurements inside 4 solar radii (p = 2.9 +/- 0.2). This may arise from the increasingly dominant effect of the magnetic field on radio wave propagation at small solar offsets. Finally, a quasiperiodic component, believed to be associated with Alfven waves, was discovered in some (but not all!) fluctuation spectra observed simultaneously at two ground stations. Characteristic periods and bulk velocities of this component were 240 +/- 30 sec and 300 +/- 60 km/s, respectively.

Seismic probing of solar flows using high-degree oscillations

International Nuclear Information System (INIS)

Haber, D.A.

1987-01-01

Employing solar-oscillation modes of degree 50 ≤ l ≤ 850, the author estimated the equatorial rotation rate with depth, searched for possible anisotropies in power for modes travelling in different directions, and examined the influence of a major flare on the oscillations. Motivated by the need in studying solar rotation for accurate frequency splittings between individual modes, different spatial-filtering methods were evaluated to determine which yield the most-accurate frequencies. A filtering method based on spherical-harmonic projection of the data is found to be superior in this regard. The various filtering techniques are applied to three days of concatenated Doppler-velocity data taken on a long, narrow grid centered on the solar disk. An inversion procedure is then performed to determine the equatorial solar rotation in the upper convection zone. The rotation rate is found to increase to a depth of about 2 Mm before decreasing over the next 14 Mm. Power in sectoral modes traveling along the equator (equatorial modes) is compared to that in poleward-traveling sectoral modes (polar modes). Full-disk Doppler velocities observed before and after a major white-light flare are compared to detect any influence of the flare on the 5-minute oscillations

Rotational motion of an artificial satellite perturbed by solar radiation pressure

International Nuclear Information System (INIS)

Moraes, R.V. de; Zanardi, M.C.

1988-01-01

The motion of a satellite about its center of mass is studied using a semi-analytical method. Torques produced by conservative and non conservative forces are considered. An analytical model is proposed for solar radiation torques. Andoyer variables are used to describe the rotational motion. Analytical equations are used to transform osculating to a mean set of differential equations. Since the mean equations are more slowly varying, a numerical integration using large step size can be performed to obtain the mean state at a later time. (author) [pt

Investigating stellar surface rotation using observations of starspots

DEFF Research Database (Denmark)

Korhonen, Heidi Helena

2011-01-01

Rapid rotation enhances the dynamo operating in stars, and thus also introduces significantly stronger magnetic activity than is seen in slower rotators. Many young cool stars still have the rapid, primordial rotation rates induced by the interstellar molecular cloud from which they were formed....... Also older stars in close binary systems are often rapid rotators. These types of stars can show strong magnetic activity and large starspots. In the case of large starspots which cause observable changes in the brightness of the star, and even in the shapes of the spectral line profiles, one can get...... information on the rotation of the star. At times even information on the spot rotation at different stellar latitudes can be obtained, similarly to the solar surface differential rotation measurements using magnetic features as tracers. Here, I will review investigations of stellar rotation based...

PRE-SUPERNOVA EVOLUTION OF ROTATING SOLAR METALLICITY STARS IN THE MASS RANGE 13-120 M {sub Sun} AND THEIR EXPLOSIVE YIELDS

Energy Technology Data Exchange (ETDEWEB)

Chieffi, Alessandro [Istituto Nazionale di Astrofisica-Istituto di Astrofisica e Planetologia Spaziali, Via Fosso del Cavaliere 100, I-00133 Roma (Italy); Limongi, Marco, E-mail: alessandro.chieffi@inaf.it, E-mail: marco.limongi@oa-roma.inaf.it [Centre for Stellar and Planetary Astrophysics, School of Mathematical Sciences, P.O. Box 28M, Monash University, Victoria 3800 (Australia)

2013-02-10

We present the first set of a new generation of models of massive stars with a solar composition extending between 13 and 120 M {sub Sun }, computed with and without the effects of rotation. We included two instabilities induced by rotation: the meridional circulation and the shear instability. We implemented two alternative schemes to treat the transport of the angular momentum: the advection-diffusion formalism and the simpler purely diffusive one. The full evolution from the pre-main sequence up to the pre-supernova stage is followed in detail with a very extended nuclear network. The explosive yields are provided for a variety of possible mass cuts and are available at the Web site http://www.iasf-roma.inaf.it/orfeo/public{sub h}tml. We find that both the He and the CO core masses are larger than those of their non-rotating counterparts. Also the C abundance left by the He burning is lower than in the non-rotating case, especially for stars with an initial mass of 13-25 M {sub Sun }, and this affects the final mass-radius relation, basically the final binding energy, at the pre-supernova stage. The elemental yields produced by a generation of stars rotating initially at 300 km s{sup -1} do not change substantially with respect to those produced by a generation of non-rotating massive stars, the main differences being a slight overproduction of the weak s-component and a larger production of F. Since rotation also affects the mass-loss rate, either directly or indirectly, we find substantial differences in the lifetimes as O-type and Wolf-Rayet subtypes between the rotating and non-rotating models. The maximum mass exploding as Type IIP supernova ranges between 15 and 20 M {sub Sun} in both sets of models (this value depends basically on the larger mass-loss rates in the red supergiant phase due to the inclusion of the dust-driven wind). This limiting value is in remarkably good agreement with current estimates.

The Dependence of Tropical Cyclone Count and Size on Rotation Rate

Science.gov (United States)

Chavas, D. R.; Reed, K. A.

2017-12-01

Both theory and idealized equilibrium modeling studies indicate that tropical cyclone size decreases with background rotation rate. In contrast, in real-world observations size tends to increase with latitude. Here we seek to resolve this apparent contradiction via a set of reduced-complexity global aquaplanet simulations with varying planetary rotation rates using the NCAR Community Atmosphere Model 5. The latitudinal distribution of both storm count and size are found to vary markedly with rotation rate, yielding insight into the dynamical constraints on tropical cyclone activity on a rotating planet. Moreover, storm size is found to vary non-monotonically with latitude, indicating that non-equilibrium effects are crucial to the life-cycle evolution of size in nature. Results are then compared to experiments in idealized, time-dependent limited-area modeling simulations using CM1 in axisymmetric and three-dimensional geometry. Taken together, this hierarchy of models is used to quantify the role of equilibrium versus transient controls on storm size and the relevance of each to real storms in nature.

Solar tracking system

Science.gov (United States)

White, P. R.; Scott, D. R. (Inventor)

1981-01-01

A solar tracker for a solar collector is described in detail. The collector is angularly oriented by a motor wherein the outputs of two side-by-side photodetectors are discriminated as to three ranges: a first corresponding to a low light or darkness condition; a second corresponding to light intensity lying in an intermediate range; and a third corresponding to light above an intermediate range, direct sunlight. The first output drives the motor to a selected maximum easterly angular position; the second enables the motor to be driven westerly at the Earth rotational rate; and the third output, the separate outputs of the two photodetectors, differentially controls the direction of rotation of the motor to effect actual tracking of the Sun.

Solar rotation and activity in the past and their possible influence upon the evolution of life

International Nuclear Information System (INIS)

Geyer, E.H.

1981-01-01

It is proposed that the rotational angular momentum of the lower Main Sequence stars determines the intensity of their magnetic spot activity. As a consequence of this feedback coupling, the stellar rotation and the activity decay exponentially by magnetic braking of the induced stellar flare- and wind-activity. Therefore, the Sun should have rotated much faster and must have shown a very enhanced activity in its early history. This strong solar activity in the past could have influenced the evolution of terrestrial life, and may explain the stagnation of maritime life for about 2 x 10 9 yr, the diversification of species during the Cambrian formation, and the land conquest by life in the upper Silurian system. (Auth.)

Solar rotation and activity in the past and their possible influence upon the evolution of life

Energy Technology Data Exchange (ETDEWEB)

Geyer, E H [Bonn Univ. (Germany, F.R.). Sternwarte

1981-06-01

It is proposed that the rotational angular momentum of the lower Main Sequence stars determines the intensity of their magnetic spot activity. As a consequence of this feedback coupling, the stellar rotation and the activity decay exponentially by magnetic braking of the induced stellar flare- and wind-activity. Therefore, the Sun should have rotated much faster and must have shown a very enhanced activity in its early history. This strong solar activity in the past could have influenced the evolution of terrestrial life, and may explain the stagnation of maritime life for about 2 x 10/sup 9/ yr, the diversification of species during the Cambrian formation, and the land conquest by life in the upper Silurian system.

Solar magnetism: a new look

International Nuclear Information System (INIS)

Golub, L.

1981-01-01

With the growing evidence for the ubiquity of magnetic fields, researchers feel a growing need for an adequate theory for the generation of such fields in nature. This article looks at the sun and its magnetic fields. The fundamental property that must be explained aside from the existence of magnetic fields is the solar cycle. The traditional picture of the solar cycle has three primary components: (1) solar activity; (2) latitude migration; and (3) Hale's law and reversal of polarity. The aspects of internal motion which can generate magnetic fields and cycles of activity like those observed are discussed. There are two major elements to the flow patterns of the sun. More important than the visible differential rotation of solar surface is the belief that the sun's interior rotates faster than the surface. It is this mechanism which probably produces the magnetic fields which bubble up from interior. It's also possible to show that this mechanism can produce the migration of solar activity. The reversal of polarity is explained by convection zones and sun's rotation. Due to x-ray imaging and improved magnetic field measurements, it has been observed that enormous quantities of magnetic flux emerge from solar interior in form of very small regions. This data along with rocket data show that the rate of generation of magnetic flux does not change during a solar cycle - instead, the observed cycle represents a shift from large emerging regions to numerous small regions and back again

Balancing the daylighting and energy performance of solar screens in residential desert buildings: Examination of screen axial rotation and opening aspect ratio

KAUST Repository

Sabry, Hanan

2014-05-01

Solar screens are typically used to control solar access into building spaces. They proved their usefulness in improving the daylighting and energy performance of buildings in the hot arid desert environments which are endowed with abundance of clear skies.The daylighting and energy performance of solar screens is affected by many parameters. These include screen perforation, depth, reflectivity and color, aspect ratio of openings, shape, tilt angle and rotation. Changing some of these parameters can improve the daylighting performance drastically. However, this can result in increased energy consumption. A balanced solution must be sought, where acceptable daylighting performance would be achieved at minimum energy consumption.This paper aims at defining solar screen designs that achieve visual comfort and at the same time minimum energy consumption in residential desert settings. The study focused on the effect of changing the solar screen axial rotation and the aspect ratio of its openings under the desert clear-sky. The individual and combined effects of changing these parameters were studied.Results of this study demonstrated that a non-rotated solar screen that has wide horizontal openings (aspect ratio of 18:1) proved to be successful in the north and south orientations. Its performance in the east/west orientations was also superior. In contrast, the screen that was rotated along its vertical axis while having small size openings (aspect ratio of 1:1) proved to be more successful in the east/west orientations. Its performance in the north orientation was also good. These solutions enhanced daylighting performance, while maintaining the energy consumption at a minimum.Moreover, it was observed that combining two screen parameters which proved useful in previous studies on daylighting or thermal performance does not add up to better solutions. The combined solutions that were tested in this study did not prove successful in satisfying daylighting and thermal

Simultaneously photocatalytic treatment of hexavalent chromium (Cr(VI)) and endocrine disrupting compounds (EDCs) using rotating reactor under solar irradiation

International Nuclear Information System (INIS)

Kim, Youngji; Joo, Hyunku; Her, Namguk; Yoon, Yeomin; Sohn, Jinsik; Kim, Sungpyo; Yoon, Jaekyung

2015-01-01

Highlights: • Self-rotating reactor including TiO 2 NTs is applied under solar irradiation. • Simultaneously photocatalysis of Cr(VI) and EDCs is observed to be up to 95%. • Photocatalytic reactions of Cr(VI) and EDCs are favorable under acidic pH. • Charge interaction and hole scavenge between TiO 2 and pollutants are synergy factors. - Abstract: In this study, simultaneous treatments, reduction of hexavalent chromium (Cr(VI)) and oxidation of endocrine disrupting compounds (EDCs), such as bisphenol A (BPA), 17α-ethinyl estradiol (EE2) and 17β-estradiol (E2), were investigated with a rotating photocatalytic reactor including TiO 2 nanotubes formed on titanium mesh substrates under solar UV irradiation. In the laboratory tests with a rotating type I reactor, synergy effects of the simultaneous photocatalytic reduction and oxidation of inorganic (Cr(VI)) and organic (BPA) pollutants were achieved. Particularly, the concurrent photocatalytic reduction of Cr(VI) and oxidation of BPA was higher under acidic conditions. The enhanced reaction efficiency of both pollutants was attributed to a stronger charge interaction between TiO 2 nanotubes (positive charge) and the anionic form of Cr(VI) (negative charge), which are prevented recombination (electron–hole pair) by the hole scavenging effect of BPA. In the extended outdoor tests with a rotating type II reactor under solar irradiation, the experiment was extended to examine the simultaneous reduction of Cr(VI) in the presence of additional EDCs, such as EE2 and E2 as well as BPA. The findings showed that synergic effect of both photocatalytic reduction and oxidation was confirmed with single-component (Cr(VI) only), two-components (Cr(VI)/BPA, Cr(VI)/EE2, and Cr(VI)/E2), and four-components (Cr(VI)/BPA/EE2/E2) under various solar irradiation conditions

Fireball flickering: the case for indirect measurement of meteoroid rotation rates

Science.gov (United States)

Beech, Martin; Brown, Peter

2000-08-01

Data collected during the Meteorite Observation and Recovery Program (MORP) indicate that 4% of bright fireballs show a periodic variation or flickering in brightness. The observed flickering frequencies vary from a few Hz to as high as 500 Hz. We interpret the flickering phenomenon in terms of meteoroid rotation. The MORP data does not reveal any apparent correlation between the flickering frequency and the properties of the meteoroid or the atmospheric flow conditions under which ablation is taking place. It is argued that the most likely cause of the flickering phenomenon is the rotational modulation of the cross-section area presented by the meteoroid to the on-coming airflow. A study is made of the Peekskill fireball and it is concluded that the meteoroid was spun-up during its long flight through the Earth's atmosphere, and that its initial brake up was due to rotational bursting. We also argue that the Peekskill event provides the best observational evidence that the flickering phenomenon is truly related to the rotation rate of the impinging meteoroid. We find that the observed rotation rates of the MORP fireballs are clustered just below the allowed limit set by rotational bursting, but argue that this is due to an observational selection effect that mitigates against the detection of low-frequency flickering.

THREE-DIMENSIONAL ATMOSPHERIC CIRCULATION OF WARM AND HOT JUPITERS: EFFECTS OF ORBITAL DISTANCE, ROTATION PERIOD, AND NONSYNCHRONOUS ROTATION

Energy Technology Data Exchange (ETDEWEB)

Showman, Adam P. [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, 1629 University Blvd., Tucson, AZ 85721 (United States); Lewis, Nikole K. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Fortney, Jonathan J., E-mail: showman@lpl.arizona.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2015-03-10

Efforts to characterize extrasolar giant planet (EGP) atmospheres have so far emphasized planets within 0.05 AU of their stars. Despite this focus, known EGPs populate a continuum of orbital separations from canonical hot Jupiter values (0.03–0.05 AU) out to 1 AU and beyond. Unlike typical hot Jupiters, these more distant EGPs will not generally be synchronously rotating. In anticipation of observations of this population, we here present three-dimensional atmospheric circulation models exploring the dynamics that emerge over a broad range of rotation rates and incident stellar fluxes appropriate for warm and hot Jupiters. We find that the circulation resides in one of two basic regimes. On typical hot Jupiters, the strong day–night heating contrast leads to a broad, fast superrotating (eastward) equatorial jet and large day–night temperature differences. At faster rotation rates and lower incident fluxes, however, the day–night heating gradient becomes less important, and baroclinic instabilities emerge as a dominant player, leading to eastward jets in the midlatitudes, minimal temperature variations in longitude, and, often, weak winds at the equator. Our most rapidly rotating and least irradiated models exhibit similarities to Jupiter and Saturn, illuminating the dynamical continuum between hot Jupiters and the weakly irradiated giant planets of our own solar system. We present infrared (IR) light curves and spectra of these models, which depend significantly on incident flux and rotation rate. This provides a way to identify the regime transition in future observations. In some cases, IR light curves can provide constraints on the rotation rate of nonsynchronously rotating planets.

THREE-DIMENSIONAL ATMOSPHERIC CIRCULATION OF WARM AND HOT JUPITERS: EFFECTS OF ORBITAL DISTANCE, ROTATION PERIOD, AND NONSYNCHRONOUS ROTATION

International Nuclear Information System (INIS)

Showman, Adam P.; Lewis, Nikole K.; Fortney, Jonathan J.

2015-01-01

Efforts to characterize extrasolar giant planet (EGP) atmospheres have so far emphasized planets within 0.05 AU of their stars. Despite this focus, known EGPs populate a continuum of orbital separations from canonical hot Jupiter values (0.03–0.05 AU) out to 1 AU and beyond. Unlike typical hot Jupiters, these more distant EGPs will not generally be synchronously rotating. In anticipation of observations of this population, we here present three-dimensional atmospheric circulation models exploring the dynamics that emerge over a broad range of rotation rates and incident stellar fluxes appropriate for warm and hot Jupiters. We find that the circulation resides in one of two basic regimes. On typical hot Jupiters, the strong day–night heating contrast leads to a broad, fast superrotating (eastward) equatorial jet and large day–night temperature differences. At faster rotation rates and lower incident fluxes, however, the day–night heating gradient becomes less important, and baroclinic instabilities emerge as a dominant player, leading to eastward jets in the midlatitudes, minimal temperature variations in longitude, and, often, weak winds at the equator. Our most rapidly rotating and least irradiated models exhibit similarities to Jupiter and Saturn, illuminating the dynamical continuum between hot Jupiters and the weakly irradiated giant planets of our own solar system. We present infrared (IR) light curves and spectra of these models, which depend significantly on incident flux and rotation rate. This provides a way to identify the regime transition in future observations. In some cases, IR light curves can provide constraints on the rotation rate of nonsynchronously rotating planets

MAGNETIC ROSSBY WAVES IN THE SOLAR TACHOCLINE AND RIEGER-TYPE PERIODICITIES

International Nuclear Information System (INIS)

Zaqarashvili, Teimuraz V.; Carbonell, Marc; Oliver, Ramon; Ballester, Jose Luis

2010-01-01

Apart from the eleven-year solar cycle, another periodicity around 155-160 days was discovered during solar cycle 21 in high-energy solar flares, and its presence in sunspot areas and strong magnetic flux has been also reported. This periodicity has an elusive and enigmatic character, since it usually appears only near the maxima of solar cycles, and seems to be related with a periodic emergence of strong magnetic flux at the solar surface. Therefore, it is probably connected with the tachocline, a thin layer located near the base of the solar convection zone, where a strong dynamo magnetic field is stored. We study the dynamics of Rossby waves in the tachocline in the presence of a toroidal magnetic field and latitudinal differential rotation. Our analysis shows that the magnetic Rossby waves are generally unstable and that the growth rates are sensitive to the magnetic field strength and to the latitudinal differential rotation parameters. Variation of the differential rotation and the magnetic field strength throughout the solar cycle enhance the growth rate of a particular harmonic in the upper part of the tachocline around the maximum of the solar cycle. This harmonic is symmetric with respect to the equator and has a period of 155-160 days. A rapid increase of the wave amplitude could give rise to a magnetic flux emergence leading to observed periodicities in solar activity indicators related to magnetic flux.

Spacecraft with gradual acceleration of solar panels

Science.gov (United States)

Merhav, Tamir R. (Inventor); Festa, Michael T. (Inventor); Stetson, Jr., John B. (Inventor)

1996-01-01

A spacecraft (8) includes a movable appendage such as solar panels (12) operated by a stepping motor (28) driven by pulses (311). In order to reduce vibration andor attitude error, the drive pulses are generated by a clock down-counter (312) with variable count ratio. Predetermined desired clock ratios are stored in selectable memories (314a-d), and the selected ratio (R) is coupled to a comparator (330) together with the current ratio (C). An up-down counter (340) establishes the current count-down ratio by counting toward the desired ratio under the control of the comparator; thus, a step change of solar panel speed never occurs. When a direction change is commanded, a flag signal generator (350) disables the selectable memories, and enables a further store (360), which generates a count ratio representing a very slow solar panel rotational rate, so that the rotational rate always slows to a low value before direction is changed. The principles of the invention are applicable to any movable appendage.

Chromospheric rotation. II. Dependence on the size of chromospheric features

Energy Technology Data Exchange (ETDEWEB)

Azzarelli, L; Casalini, P; Cerri, S; Denoth, F [Consiglio Nazionale delle Ricerche, Pisa (Italy). Ist. di Elaborazione della Informazione

1979-08-01

The dependence of solar rotation on the size of the chromospheric tracers is considered. On the basis of an analysis of Ca II K/sub 3/ daily filtergrams taken in the period 8 May-14 August, 1972, chromospheric features can be divided into two classes according to their size. Features with size falling into the range 24 000-110 000 km can be identified with network elements, while those falling into the range 120 000-300 000 km with active regions, or brightness features of comparable size present at high latitudes. The rotation rate is determined separately for the two families of chromospheric features by means of a cross-correlation technique directly yields the average daily displacement of tracers due to rotation. Before computing the cross-correlation functions, chromospheric brightness data have been filtered with appropriate bandpass and highpass filters for separating spatial periodicities whose wavelengths fall into the two ranges of size, characteristic of the network pattern and of the activity centers. A difference less than 1% of the rotation rate of the two families of chromospheric features has been found. This is an indication for a substantial corotation at chromospheric levels of different short-lived features, both related to solar activity and controlled by the convective supergranular motions.

Chaotic Zones around Rotating Small Bodies

Energy Technology Data Exchange (ETDEWEB)

Lages, José; Shevchenko, Ivan I. [Institut UTINAM, Observatoire des Sciences de l’Univers THETA, CNRS, Université de Franche-Comté, Besançon F-25030 (France); Shepelyansky, Dima L., E-mail: jose.lages@utinam.cnrs.fr [Laboratoire de Physique Théorique du CNRS, IRSAMC, Université de Toulouse, UPS, Toulouse F-31062 (France)

2017-06-01

Small bodies of the solar system, like asteroids, trans-Neptunian objects, cometary nuclei, and planetary satellites, with diameters smaller than 1000 km usually have irregular shapes, often resembling dumb-bells or contact binaries. The spinning of such a gravitating dumb-bell creates around it a zone of chaotic orbits. We determine its extent analytically and numerically. We find that the chaotic zone swells significantly if the rotation rate is decreased; in particular, the zone swells more than twice if the rotation rate is decreased 10 times with respect to the “centrifugal breakup” threshold. We illustrate the properties of the chaotic orbital zones in examples of the global orbital dynamics about asteroid 243 Ida (which has a moon, Dactyl, orbiting near the edge of the chaotic zone) and asteroid 25143 Itokawa.

Advancements in solar stills for enhanced flow rate

Science.gov (United States)

Mishra, Sourav; Dubey, Maneesh; Raghuwanshi, Jitendra; Sharma, Vipin

2018-05-01

All over the world there is a scarcity of water and it is difficult to access potable water. Due to this most of the people are affected by diseases that are caused due to drinking of polluted water. There are technologies through which we can purify polluted water but the only problem is these technologies uses electrical energy. Since solar energy is abundant in nature therefore we can use solar as an energy source in solar stills for water distillation. Solar stills can be used in village areas where there is no electricity. It is simple and also economic in construction. This article addresses advancement in solar distillation and usage of nanofluids for enhancement in flow rate.

Differential Rotation via Tracking of Coronal Bright Points.

Science.gov (United States)

McAteer, James; Boucheron, Laura E.; Osorno, Marcy

2016-05-01

The accurate computation of solar differential rotation is important both as a constraint for, and evidence towards, support of models of the solar dynamo. As such, the use of Xray and Extreme Ultraviolet bright points to elucidate differential rotation has been studied in recent years. In this work, we propose the automated detection and tracking of coronal bright points (CBPs) in a large set of SDO data for re-evaluation of solar differential rotation and comparison to other results. The big data aspects, and high cadence, of SDO data mitigate a few issues common to detection and tracking of objects in image sequences and allow us to focus on the use of CBPs to determine differential rotation. The high cadence of the data allows to disambiguate individual CBPs between subsequent images by allowing for significant spatial overlap, i.e., by the fact that the CBPs will rotate a short distance relative to their size. The significant spatial overlap minimizes the effects of incorrectly detected CBPs by reducing the occurrence of outlier values of differential rotation. The big data aspects of the data allows to be more conservative in our detection of CBPs (i.e., to err on the side of missing CBPs rather than detecting extraneous CBPs) while still maintaining statistically larger populations over which to study characteristics. The ability to compute solar differential rotation through the automated detection and tracking of a large population of CBPs will allow for further analyses such as the N-S asymmetry of differential rotation, variation of differential rotation over the solar cycle, and a detailed study of the magnetic flux underlying the CBPs.

Internal Flow of Contra-Rotating Small Hydroturbine at Off- Design Flow Rates

Science.gov (United States)

SHIGEMITSU, Toru; TAKESHIMA, Yasutoshi; OGAWA, Yuya; FUKUTOMI, Junichiro

2016-11-01

Small hydropower generation is one of important alternative energy, and enormous potential lie in the small hydropower. However, efficiency of small hydroturbines is lower than that of large one. Then, there are demands for small hydroturbines to keep high performance in wide flow rate range. Therefore, we adopted contra-rotating rotors, which can be expected to achieve high performance. In this research, performance of the contra-rotating small hydroturbine with 60mm casing diameter was investigated by an experiment and numerical analysis. Efficiency of the contra-rotating small hydroturbine was high in pico-hydroturbine and high efficiency could be kept in wide flow rate range, however the performance of a rear rotor decreased significantly in partial flow rates. Then, internal flow condition, which was difficult to measure experimentally, was investigated by the numerical flow analysis. Then, a relation between the performance and internal flow condition was considered by the numerical analysis result.

Early postoperative fluoroquinolone use is associated with an increased revision rate after arthroscopic rotator cuff repair.

Science.gov (United States)

Cancienne, Jourdan M; Brockmeier, Stephen F; Rodeo, Scott A; Young, Chris; Werner, Brian C

2017-07-01

To evaluate the association of postoperative fluoroquinolone use following arthroscopic primary rotator cuff repair with failure requiring revision rotator cuff repair. An insurance database was queried for patients undergoing rotator cuff repair from 2007 to 2015. These patients were divided into three groups: (1) patients prescribed fluoroquinolones within 6 months postoperatively (divided into 0-2, 2-4, and 4-6 months), (2) a matched negative control cohort of patients not prescribed fluoroquinolones, and (3) a matched positive control cohort of patients prescribed fluoroquinolones between 6 and 18 months following rotator cuff repair. Rates of failure requiring revision rotator cuff repair were compared within 2 years. A total of 1292 patients were prescribed fluoroquinolones within 6 months after rotator cuff repair, including 442 within 2 months, 433 within 2 to 4 months, and 417 within 4 to 6 months, and were compared to 5225 matched negative controls and 1597 matched positive controls. The rate of revision rotator cuff repair was significantly higher in patients prescribed fluoroquinolones within 2 months (6.1 %) compared to matched negative (2.2 %, P = 0.0009) and positive controls (2.4 %, P = 0.0026). There were no significant differences in the rate of revision rotator cuff repair when fluoroquinolones were prescribed >2 months after rotator cuff repair. Early use of fluoroquinolones following rotator cuff repair was independently associated with significantly increased rates of failure requiring revision rotator cuff repair. This is the first clinical study examining the association of postoperative fluoroquinolone use with failure following arthroscopic rotator cuff repair. III.

Thermal bifurcation in the upper solar photosphere inferred from heterodyne spectroscopy of OH rotational lines

Science.gov (United States)

Deming, D.; Hillman, J. J.; Kostiuk, T.; Mumma, M. J.; Zipoy, D. M.

1984-01-01

Low noise high spectral resolution observations of two pure rotation transitions of OH from the solar photosphere were obtained. The observations were obtained using the technique of optically null-balanced infrared heterodyne spectroscopy, and consist of center-to-limb line profiles of a v=1 and a v=0 transition near 12 microns. These lines should be formed in local thermodynamic equilibrium (LTE), and are diagnostics of the thermal structure of the upper photosphere. The v=0 R22 (24.5)e line strengthens at the solar limb, in contradiction to the predictions of current one dimensional photospheric models. Data for this line support a two dimensional model in which horizontal thermal fluctuations of order + or - 800K occur in the region Tau (sub 5000) approximately .001 to .01. This thermal bifurcation may be maintained by the presence of magnetic flux tubes, and may be related to the solar limb extensions observed in the 30 to 200 micron region.

Resonance of about-weekly human heart rate rhythm with solar activity change.

Science.gov (United States)

Cornelissen, G; Halberg, F; Wendt, H W; Bingham, C; Sothern, R B; Haus, E; Kleitman, E; Kleitman, N; Revilla, M A; Revilla, M; Breus, T K; Pimenov, K; Grigoriev, A E; Mitish, M D; Yatsyk, G V; Syutkina, E V

1996-12-01

In several human adults, certain solar activity rhythms may influence an about 7-day rhythm in heart rate. When no about-weekly feature was found in the rate of change in sunspot area, a measure of solar activity, the double amplitude of a circadian heart rate rhythm, approximated by the fit of a 7-day cosine curve, was lower, as was heart rate corresponds to about-weekly features in solar activity and/or relates to a sunspot cycle.

Long-Period Tidal Variations of the Earth's Rotation Rate

Science.gov (United States)

Desai, S.; Gross, R.; Wahr, J.

1999-01-01

Long-period tidal variations of the Earth's rotation rate are caused by the redistribution of mass associated with the respective elastic solid Earth tides, the ocean tide heights, and the anelasticity of the Earth's mantle, and by the relative angular momentum associated with the long-period ocean tide currents.

Rate of rotation measurement using back-EMFS associated with windings of a brushless DC motor

Science.gov (United States)

Howard, David E. (Inventor)

2000-01-01

A system and method are provided for measuring rate of rotation. A brushless DC motor is rotated and produces a back electromagnetic force (emf) on each winding thereof. Each winding's back-emf is integrated and multiplied by the back-emf associated with an adjacent winding. The multiplied outputs associated with each winding are combined to produce a directionally sensitive DC output proportional only to the rate of rotation of the motor's shaft.

Solar panel thermal cycling testing by solar simulation and infrared radiation methods

Science.gov (United States)

Nuss, H. E.

1980-01-01

For the solar panels of the European Space Agency (ESA) satellites OTS/MAROTS and ECS/MARECS the thermal cycling tests were performed by using solar simulation methods. The performance data of two different solar simulators used and the thermal test results are described. The solar simulation thermal cycling tests for the ECS/MARECS solar panels were carried out with the aid of a rotatable multipanel test rig by which simultaneous testing of three solar panels was possible. As an alternative thermal test method, the capability of an infrared radiation method was studied and infrared simulation tests for the ultralight panel and the INTELSAT 5 solar panels were performed. The setup and the characteristics of the infrared radiation unit using a quartz lamp array of approx. 15 sq and LN2-cooled shutter and the thermal test results are presented. The irradiation uniformity, the solar panel temperature distribution, temperature changing rates for both test methods are compared. Results indicate the infrared simulation is an effective solar panel thermal testing method.

Measurement of mean rotation and strain-rate tensors by using stereoscopic PIV

DEFF Research Database (Denmark)

Özcan, Oktay; Meyer, Knud Erik; Larsen, Poul Scheel

2005-01-01

A technique is described for measuring the mean velocity gradient (rate-of-displacement) tensor by using a conventional stereoscopic particle image velocimetry (SPIV) system. Planar measurement of the mean vorticity vector, rate-of-rotation and rate-of-strain tensors and the production of turbule...

Faraday rotation fluctuations of MESSENGER radio signals through the equatorial lower corona near solar minimum

Science.gov (United States)

Wexler, D. B.; Jensen, E. A.; Hollweg, J. V.; Heiles, C.; Efimov, A. I.; Vierinen, J.; Coster, A. J.

2017-02-01

Faraday rotation (FR) of transcoronal radio transmissions from spacecraft near superior conjunction enables study of the temporal variations in coronal plasma density, velocity, and magnetic field. The MESSENGER spacecraft 8.4 GHz radio, transmitting through the corona with closest line-of-sight approach 1.63-1.89 solar radii and near-equatorial heliolatitudes, was recorded soon after the deep solar minimum of solar cycle 23. During egress from superior conjunction, FR gradually decreased, and an overlay of wave-like FR fluctuations (FRFs) with periods of hundreds to thousands of seconds was found. The FRF power spectrum was characterized by a power law relation, with the baseline spectral index being -2.64. A transient power increase showed relative flattening of the spectrum and bands of enhanced spectral power at 3.3 mHz and 6.1 mHz. Our results confirm the presence of coronal FRF similar to those described previously at greater solar offset. Interpreted as Alfvén waves crossing the line of sight radially near the proximate point, low-frequency FRF convey an energy flux density higher than that of the background solar wind kinetic energy, but only a fraction of that required to accelerate the solar wind. Even so, this fraction is quite variable and potentially escalates to energetically significant values with relatively modest changes in estimated magnetic field strength and electron concentration. Given the uncertainties in these key parameters, as well as in solar wind properties close to the Sun at low heliolatitudes, we cannot yet confidently assign the quantitative role for Alfvén wave energy from this region in driving the slow solar wind.

Effects of solar collecting area and water flow rate on the performance of a sand bed solar collector

International Nuclear Information System (INIS)

Maganhar, A.L.; Memon, A.H.; Panhwar, M.I.

2005-01-01

The often discussed renewable sources of energy have been great interest to energy researchers and planners for quite some time. The primary of renewing all sources of energy is the sun. There have been two main problems not yet fully resolved. One is the large scale production of energy and other is the cost factor. In the present study, the cost factor is under consideration. In this regard a non-conventional solar collector using indigenous material (pit sand) as solar absorber is designed and manufactured. This paper presents the results of an investigation of the effect of solar collecting area and water flow rate on the performance of a pit sand bed solar collector especially in terms of rise in water temperature. Three pit sand solar collectors of area 1m/sup 2/ each were connected in series to enhance the collecting area and the system was tested for different flow rates. Experimental results proved that there was increase in water temperature with increase in solar collecting area an decreases in water temperature with increase in flow rate. (author)

Efficiencies of flat plate solar collectors at different flow rates

DEFF Research Database (Denmark)

Chen, Ziqian; Furbo, Simon; Perers, Bengt

2012-01-01

Two flat plate solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one collector is equipped with an ETFE foil between...... the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rate are obtained. The calculated efficiencies are in good agreement...

Meridional Motions and Reynolds Stress Determined by Using Kanzelhöhe Drawings and White Light Solar Images from 1964 to 2016

Science.gov (United States)

Ruždjak, Domagoj; Sudar, Davor; Brajša, Roman; Skokić, Ivica; Poljančić Beljan, Ivana; Jurdana-Šepić, Rajka; Hanslmeier, Arnold; Veronig, Astrid; Pötzi, Werner

2018-04-01

Sunspot position data obtained from Kanzelhöhe Observatory for Solar and Environmental Research (KSO) sunspot drawings and white light images in the period 1964 to 2016 were used to calculate the rotational and meridional velocities of the solar plasma. Velocities were calculated from daily shifts of sunspot groups and an iterative process of calculation of the differential rotation profiles was used to discard outliers. We found a differential rotation profile and meridional motions in agreement with previous studies using sunspots as tracers and conclude that the quality of the KSO data is appropriate for analysis of solar velocity patterns. By analyzing the correlation and covariance of meridional velocities and rotation rate residuals we found that the angular momentum is transported towards the solar equator. The magnitude and latitudinal dependence of the horizontal component of the Reynolds stress tensor calculated is sufficient to maintain the observed solar differential rotation profile. Therefore, our results confirm that the Reynolds stress is the dominant mechanism responsible for transport of angular momentum towards the solar equator.

Radio Remote Sensing of Coronal Mass Ejections: Implications for Parker Solar Probe and Solar Orbiter

Science.gov (United States)

Kooi, J. E.; Thomas, N. C.; Guy, M. B., III; Spangler, S. R.

2017-12-01

Coronal mass ejections (CMEs) are fast-moving magnetic field structures of enhanced plasma density that play an important role in space weather. The Solar Orbiter and Parker Solar Probe will usher in a new era of in situ measurements, probing CMEs within distances of 60 and 10 solar radii, respectively. At the present, only remote-sensing techniques such as Faraday rotation can probe the plasma structure of CMEs at these distances. Faraday rotation is the change in polarization position angle of linearly polarized radiation as it propagates through a magnetized plasma (e.g. a CME) and is proportional to the path integral of the electron density and line-of-sight magnetic field. In conjunction with white-light coronagraph measurements, Faraday rotation observations have been used in recent years to determine the magnetic field strength of CMEs. We report recent results from simultaneous white-light and radio observations made of a CME in July 2015. We made radio observations using the Karl G. Jansky Very Large Array (VLA) at 1 - 2 GHz frequencies of a set of radio sources through the solar corona at heliocentric distances that ranged between 8 - 23 solar radii. These Faraday rotation observations provide a priori estimates for comparison with future in situ measurements made by the Solar Orbiter and Parker Solar Probe. Similar Faraday rotation observations made simultaneously with observations by the Solar Orbiter and Parker Solar Probe in the future could provide information about the global structure of CMEs sampled by these probes and, therefore, aid in understanding the in situ measurements.

Differential rotation of the Sun and the Maunder minimum of solar activity

International Nuclear Information System (INIS)

Ikhsanov, R.N.; Vitinskij, Yu.I.

1980-01-01

Nature of differential rotation of the Sun is discussed. Investigation of long term changes in differential rotation separately for two phase of 11 year cycle of the Sun activity is carried out. Data on heliographic coordinates for every day of all groups of the Sun spots for the years preceding the epoch of the minimum of the 11 year cycle and the Sun groups for the years of maximum from ''Greenwich Photoheliographic Results'' for 1875-1954 are used as initial material. It is shown that differential rotation of the Sun changes in time from one 11 year cycle of the Sun activity to another. This change is connected with the power of 11 year cycle. During the maximum phase of 11 year cycle differentiality of the rotation increases in the cycles where the cycle maximum is higher. Before the minimum of 11 year cycle rotation differentiability is lower in the cycles for which activity maximum is higher in the next 11 year cycle. Equatorial rate of the Sun rotation increases with the decrease in the cycle power when the maximum Wolf number is less than 110. The mentioned regularities took place both during Maunder minimum and before its beginning [ru

An Investigation of the Sources of Earth-directed Solar Wind during Carrington Rotation 2053

Science.gov (United States)

Fazakerley, A. N.; Harra, L. K.; van Driel-Gesztelyi, L.

2016-06-01

In this work we analyze multiple sources of solar wind through a full Carrington Rotation (CR 2053) by analyzing the solar data through spectroscopic observations of the plasma upflow regions and the in situ data of the wind itself. Following earlier authors, we link solar and in situ observations by a combination of ballistic backmapping and potential-field source-surface modeling. We find three sources of fast solar wind that are low-latitude coronal holes. The coronal holes do not produce a steady fast wind, but rather a wind with rapid fluctuations. The coronal spectroscopic data from Hinode’s Extreme Ultraviolet Imaging Spectrometer show a mixture of upflow and downflow regions highlighting the complexity of the coronal hole, with the upflows being dominant. There is a mix of open and multi-scale closed magnetic fields in this region whose (interchange) reconnections are consistent with the up- and downflows they generate being viewed through an optically thin corona, and with the strahl directions and freeze-in temperatures found in in situ data. At the boundary of slow and fast wind streams there are three short periods of enhanced-velocity solar wind, which we term intermediate based on their in situ characteristics. These are related to active regions that are located beside coronal holes. The active regions have different magnetic configurations, from bipolar through tripolar to quadrupolar, and we discuss the mechanisms to produce this intermediate wind, and the important role that the open field of coronal holes adjacent to closed-field active regions plays in the process.

AN INVESTIGATION OF THE SOURCES OF EARTH-DIRECTED SOLAR WIND DURING CARRINGTON ROTATION 2053

Energy Technology Data Exchange (ETDEWEB)

Fazakerley, A. N.; Harra, L. K.; Van Driel-Gesztelyi, L., E-mail: a.fazakerley@ucl.ac.uk [Mullard Space Science Laboratory, University College London (United Kingdom)

2016-06-01

In this work we analyze multiple sources of solar wind through a full Carrington Rotation (CR 2053) by analyzing the solar data through spectroscopic observations of the plasma upflow regions and the in situ data of the wind itself. Following earlier authors, we link solar and in situ observations by a combination of ballistic backmapping and potential-field source-surface modeling. We find three sources of fast solar wind that are low-latitude coronal holes. The coronal holes do not produce a steady fast wind, but rather a wind with rapid fluctuations. The coronal spectroscopic data from Hinode ’s Extreme Ultraviolet Imaging Spectrometer show a mixture of upflow and downflow regions highlighting the complexity of the coronal hole, with the upflows being dominant. There is a mix of open and multi-scale closed magnetic fields in this region whose (interchange) reconnections are consistent with the up- and downflows they generate being viewed through an optically thin corona, and with the strahl directions and freeze-in temperatures found in in situ data. At the boundary of slow and fast wind streams there are three short periods of enhanced-velocity solar wind, which we term intermediate based on their in situ characteristics. These are related to active regions that are located beside coronal holes. The active regions have different magnetic configurations, from bipolar through tripolar to quadrupolar, and we discuss the mechanisms to produce this intermediate wind, and the important role that the open field of coronal holes adjacent to closed-field active regions plays in the process.

QUASI-BIENNIAL OSCILLATIONS IN THE SOLAR TACHOCLINE CAUSED BY MAGNETIC ROSSBY WAVE INSTABILITIES

International Nuclear Information System (INIS)

Zaqarashvili, Teimuraz V.; Carbonell, Marc; Oliver, Ramon; Ballester, Jose Luis

2010-01-01

Quasi-biennial oscillations (QBOs) are frequently observed in solar activity indices. However, no clear physical mechanism for the observed variations has been suggested so far. Here, we study the stability of magnetic Rossby waves in the solar tachocline using the shallow water magnetohydrodynamic approximation. Our analysis shows that the combination of typical differential rotation and a toroidal magnetic field with a strength of ≥10 5 G triggers the instability of the m = 1 magnetic Rossby wave harmonic with a period of ∼2 years. This harmonic is antisymmetric with respect to the equator and its period (and growth rate) depends on the differential rotation parameters and magnetic field strength. The oscillations may cause a periodic magnetic flux emergence at the solar surface and consequently may lead to the observed QBO in solar activity features. The period of QBOs may change throughout a cycle, and from cycle to cycle, due to variations of the mean magnetic field and differential rotation in the tachocline.

A rapid decrease in the rotation rate of comet 41P/Tuttle-Giacobini-Kresák.

Science.gov (United States)

Bodewits, Dennis; Farnham, Tony L; Kelley, Michael S P; Knight, Matthew M

2018-01-10

Cometary outgassing can produce torques that change the spin state of the cometary nucleus, which in turn influences the evolution and lifetime of the comet. If these torques increase the rate of rotation to the extent that centripetal forces exceed the material strength of the nucleus, the comet can fragment. Torques that slow down the rotation can cause the spin state to become unstable, but if the torques persist the nucleus can eventually reorient itself and the rotation rate can increase again. Simulations predict that most comets go through a short phase of rapid changes in spin state, after which changes occur gradually over longer times. Here we report observations of comet 41P/Tuttle-Giacobini-Kresák during its close approach to Earth (0.142 astronomical units, approximately 21 million kilometres, on 1 April 2017) that reveal a rapid decrease in rotation rate. Between March and May 2017, the apparent rotation period of the nucleus increased from 20 hours to more than 46 hours-a rate of change of more than an order of magnitude larger than has hitherto been measured. This phenomenon must have been caused by the gas emission from the comet aligning in such a way that it produced an anomalously strong torque that slowed the spin rate of the nucleus. The behaviour of comet 41P/Tuttle-Giacobini-Kresák suggests that it is in a distinct evolutionary state and that its rotation may be approaching the point of instability.

A rapid decrease in the rotation rate of comet 41P/Tuttle–Giacobini–Kresák

Science.gov (United States)

Bodewits, Dennis; Farnham, Tony L.; Kelley, Michael S. P.; Knight, Matthew M.

2018-01-01

Cometary outgassing can produce torques that change the spin state of the cometary nucleus, which in turn influences the evolution and lifetime of the comet. If these torques increase the rate of rotation to the extent that centripetal forces exceed the material strength of the nucleus, the comet can fragment. Torques that slow down the rotation can cause the spin state to become unstable, but if the torques persist the nucleus can eventually reorient itself and the rotation rate can increase again. Simulations predict that most comets go through a short phase of rapid changes in spin state, after which changes occur gradually over longer times. Here we report observations of comet 41P/Tuttle–Giacobini–Kresák during its close approach to Earth (0.142 astronomical units, approximately 21 million kilometres, on 1 April 2017) that reveal a rapid decrease in rotation rate. Between March and May 2017, the apparent rotation period of the nucleus increased from 20 hours to more than 46 hours—a rate of change of more than an order of magnitude larger than has hitherto been measured. This phenomenon must have been caused by the gas emission from the comet aligning in such a way that it produced an anomalously strong torque that slowed the spin rate of the nucleus. The behaviour of comet 41P/Tuttle–Giacobini–Kresák suggests that it is in a distinct evolutionary state and that its rotation may be approaching the point of instability.

Atmospheric acceleration and Earth-expansion deceleration of the Earth rotation

Directory of Open Access Journals (Sweden)

Wenbin Shen

2017-11-01

Full Text Available Previous studies suggest that tidal friction gives rise to the secular deceleration of the Earth rotation by a quantity of about 2.25 ms/cy. Here we just consider additional contributions to the secular Earth rotation deceleration. Atmospheric solar semi-diurnal tide has a small amplitude and certain amount of phase lead. This periodic global air-mass excess distribution exerts a quasi-constant torque to accelerate the Earth's spin rotation. Using an updated atmospheric tide model, we re-estimate the amounts of this atmospheric acceleration torque and corresponding energy input, of which the associated change rate in LOD (length of day is −0.1 ms/cy. In another aspect, evidences from space-geodesy and sea level rise observations suggest that Earth expands at a rate of 0.35 mm/yr in recent decades, which gives rise to the increase of LOD at rate of 1.0 ms/cy. Hence, if the previous estimate due to the tidal friction is correct, the secular Earth rotation deceleration due to tidal friction and Earth expansion should be 3.15 ms/cy.

The sun as a star: Solar phenomena and stellar applications

International Nuclear Information System (INIS)

Noyes, R.W.

1981-01-01

Our Sun is a run-of-the-mill star, having no obvious extremes of stellar properties. For this reason it is perhaps more, rather than less, interesting as an astrophysical object, for its sameness to other stars suggests that in studying the Sun, we are studying at close hand common, rather than unusual stellar phenomena. Conversely, comparative study of the Sun and other solar-type stars is an invaluable tool for solar physics, for two reasons: First, it allows us to explore how solar properties and phenomena depend on parameters we cannot vary on the Sun - most fundamentally, rotation rate and mass. Second, study of solar-like stars of different ages allows us to see how stellar and solar phenomena depend on age; study of other stars may be one of the best ways to infer the earlier history of the Sun, as well as its future history. In this review we shall concentrate on phenomena common to the Sun and solar-type (main sequence) stars with different fundamental properties such as mass, age, and rotation. (orig.)

Magnetism, planetary rotation and convection in the solar system

CERN Document Server

1985-01-01

On the 6th, 7th' and 8th April 1983, a conference entitled "Magnetism, planetary rotation and convection in the Solar System" was held in the School of Physics at the University of Newcastle upon Tyne. The purpose of the meeting was to celebrate the 60th birthday of Prof. Stanley Keith Runcorn and his, and his students' and associates', several decades of scientific achievement. The social programme, which consisted of excursions in Northumberland and Durham with visits to ancient castles and churches, to Hexham Abbey and Durham Cathedral, and dinners in Newcastle and Durham, was greatly enjoyed by those attending the meeting and by their guests. The success ofthe scientific programme can be judged by this special edition of Geophysical Surveys which is derived mainly from the papers given at the meeting. The story starts in the late 1940s when the question of the origin of the magnetic field of the Earth and such other heavenly bodies as had at that time been discovered as having a magnetic field, was exerci...

Long-Term Variability of the Sun in the Context of Solar-Analog Stars

Science.gov (United States)

Egeland, Ricky

2018-06-01

The Sun is the best observed object in astrophysics, but despite this distinction the nature of its well-ordered generation of magnetic field in 11-year activity cycles remains a mystery. In this work, we place the solar cycle in a broader context by examining the long-term variability of solar analog stars within 5% of the solar effective temperature, but varied in rotation rate and metallicity. Emission in the Fraunhofer H & K line cores from singly-ionized calcium in the lower chromosphere is due to magnetic heating, and is a proven proxy for magnetic flux on the Sun. We use Ca H & K observations from the Mount Wilson Observatory HK project, the Lowell Observatory Solar Stellar Spectrograph, and other sources to construct composite activity time series of over 100 years in length for the Sun and up to 50 years for 26 nearby solar analogs. Archival Ca H & K observations of reflected sunlight from the Moon using the Mount Wilson instrument allow us to properly calibrate the solar time series to the S-index scale used in stellar studies. We find the mean solar S-index to be 5–9% lower than previously estimated, and the amplitude of activity to be small compared to active stars in our sample. A detailed look at the young solar analog HD 30495, which rotates 2.3 times faster than the Sun, reveals a large amplitude ~12-year activity cycle and an intermittent short-period variation of 1.7 years, comparable to the solar variability time scales despite its faster rotation. Finally, time series analyses of the solar analog ensemble and a quantitative analysis of results from the literature indicate that truly Sun-like cyclic variability is rare, and that the amplitude of activity over both long and short timescales is linearly proportional to the mean activity. We conclude that the physical conditions conducive to a quasi-periodic magnetic activity cycle like the Sun’s are rare in stars of approximately the solar mass, and that the proper conditions may be restricted

CdS films deposited by chemical bath under rotation

International Nuclear Information System (INIS)

Oliva-Aviles, A.I.; Patino, R.; Oliva, A.I.

2010-01-01

Cadmium sulfide (CdS) films were deposited on rotating substrates by the chemical bath technique. The effects of the rotation speed on the morphological, optical, and structural properties of the films were discussed. A rotating substrate-holder was fabricated such that substrates can be taken out from the bath during the deposition. CdS films were deposited at different deposition times (10, 20, 30, 40 and 50 min) onto Corning glass substrates at different rotation velocities (150, 300, 450, and 600 rpm) during chemical deposition. The chemical bath was composed by CdCl 2 , KOH, NH 4 NO 3 and CS(NH 2 ) 2 as chemical reagents and heated at 75 deg. C. The results show no critical effects on the band gap energy and the surface roughness of the CdS films when the rotation speed changes. However, a linear increase on the deposition rate with the rotation energy was observed, meanwhile the stoichiometry was strongly affected by the rotation speed, resulting a better 1:1 Cd/S ratio as speed increases. Rotation effects may be of interest in industrial production of CdTe/CdS solar cells.

CdS films deposited by chemical bath under rotation

Energy Technology Data Exchange (ETDEWEB)

Oliva-Aviles, A.I., E-mail: aoliva@mda.cinvestav.mx [Centro de Investigacion y de Estudios Avanzados Unidad Merida, Departamento de Fisica Aplicada. A.P. 73-Cordemex, 97310 Merida, Yucatan (Mexico); Patino, R.; Oliva, A.I. [Centro de Investigacion y de Estudios Avanzados Unidad Merida, Departamento de Fisica Aplicada. A.P. 73-Cordemex, 97310 Merida, Yucatan (Mexico)

2010-08-01

Cadmium sulfide (CdS) films were deposited on rotating substrates by the chemical bath technique. The effects of the rotation speed on the morphological, optical, and structural properties of the films were discussed. A rotating substrate-holder was fabricated such that substrates can be taken out from the bath during the deposition. CdS films were deposited at different deposition times (10, 20, 30, 40 and 50 min) onto Corning glass substrates at different rotation velocities (150, 300, 450, and 600 rpm) during chemical deposition. The chemical bath was composed by CdCl{sub 2}, KOH, NH{sub 4}NO{sub 3} and CS(NH{sub 2}){sub 2} as chemical reagents and heated at 75 deg. C. The results show no critical effects on the band gap energy and the surface roughness of the CdS films when the rotation speed changes. However, a linear increase on the deposition rate with the rotation energy was observed, meanwhile the stoichiometry was strongly affected by the rotation speed, resulting a better 1:1 Cd/S ratio as speed increases. Rotation effects may be of interest in industrial production of CdTe/CdS solar cells.

A theoretical study of rotatable renewable energy system for stratospheric airship

International Nuclear Information System (INIS)

Lv, Mingyun; Li, Jun; Zhu, Weiyu; Du, Huafei; Meng, Junhui; Sun, Kangwen

2017-01-01

Highlights: • A new rotatable renewable energy system is designed for stratospheric airship. • A theoretical model of optimal rotation angle and required area are studied. • The effects of latitude and date on output energy per day are investigated. • The advantages of the rotatable renewable energy system are studied. - Abstract: Renewable energy system is very critical for solving the energy problem of a long endurance stratospheric airship. Output performance of the traditional solar array fixed on the upper surface of the airship remains to be improved to reduce the area and weight of renewable energy system. Inspired by the solar tracking system and kirigami, a rotatable renewable energy system (mainly including solar array) is designed to improve the current status of the energy system. The advantages of the rotatable solar array are studied using a MATLAB computer program based on the theoretical model established in this paper. The improvements in output energy and required area of the solar array were compared between the traditional airship and improved one. Studies had shown that the rotatable renewable energy system made the total weight of energy system decreased by 1000 kg when the maximum design speed of the airship was greater than 22 m/s. The results demonstrate that the rotatable renewable energy system for the airship can be a good way to improve the output performance of solar array, and the conceptual design and theoretical model suggest a pathway towards solving the energy problem of a stratospheric airship.

The effects of mantle and anelasticity on nutations, earth tides, and tidal variations in rotation rate

Science.gov (United States)

Wahr, John; Bergen, Zachary

1986-01-01

The paper models the effects of mantle anelasticity on luni-solar nutations, on tidal deformation, on tidal variations in rotation rate, and on the eigenfrequency of the free core nutation. The results can be used to invert observations to solve for the anelastic contributions to the shear and bulk moduli of the upper and lower mantle. Specific anelastic models are used to numerically estimate the effects of anelasticity on these geodetic observables. The nutation estimates are compared with observational results. Among the conclusions: (1) mantle anelasticity is likely to be the most important source of damping for the free core nutation; (2) present VLBI nutation results are, in principle, accurate enough to usefully bound anelasticity at diurnal periods. But the discrepancy between the VLBI observed nutations and the 1984 IAU nutation model cannot be explained by anelasticity and is not yet well enough understood to allow anelasticity to be determined from the data.

Recommendations for the performance rating of flat plate terrestrial photovoltaic solar panels

Science.gov (United States)

Treble, F. C.

1976-01-01

A review of recommendations for standardizing the performance rating of flat plate terrestrial solar panels is given to develop an international standard code of practice for performance rating. Required data to characterize the performance of a solar panel are listed. Other items discussed are: (1) basic measurement procedures; (2) performance measurement in natural sunlight and simulated sunlight; (3) standard solar cells; (4) the normal incidence method; (5) global method and (6) definition of peak power.

Design and Development of a Solar Thermal Collector with Single Axis Solar Tracking Mechanism

Directory of Open Access Journals (Sweden)

Theebhan Mogana

2016-01-01

Full Text Available The solar energy is a source of energy that is abundant in Malaysia and can be easily harvested. However, because of the rotation of the Earth about its axis, it is impossible to harvest the solar energy to the maximum capacity if the solar thermal collector is placed fix to a certain angle. In this research, a solar thermal dish with single axis solar tracking mechanism that will rotate the dish according to the position of the sun in the sky is designed and developed, so that more solar rays can be reflected to a focal point and solar thermal energy can be harvested from the focal point. Data were collected for different weather conditions and performance of the solar thermal collector with a solar tracker were studied and compared with stationary solar thermal collector.

The impact of changing solar screen rotation angle and its opening aspect ratios on Daylight Availability in residential desert buildings

KAUST Repository

Sherif, Ahmed H.

2012-11-01

In desert sunny clear-sky regions solar penetration can become excessive. This can cause non-uniform daylight distribution, glare and high solar heat gain, affecting both visual and thermal comfort. Shading devices, such as solar screens, were usually used to diffuse and prevent direct solar penetration into spaces. This paper investigates the impact of changing solar screen axial rotation angle and screen opening aspect ratio on daylighting performance in a typical residential living room space under the desert sunny clear-sky. The larger aim is to arrive at efficient solar screen designs that suit the different orientations.The study was divided into three consecutive phases. In phase one, the effect of the two parameters on Daylight Availability was tested. The solar screen was axially rotated by three different angles at 10° increments. Also, the aspect ratio of the screen opening in both horizontal and vertical directions was changed systematically. Simulation was conducted using the annual Daylight Dynamic Performance Metrics (DDPMs). In phase two, the Annual Daylight Glare Probability (DGP) metric was evaluated for the cases that were found adequate in phase one. In the third phase, the annual solar energy transmittance through the screen was calculated for the cases that achieved acceptable performance in the two previous phases in order to identify the more energy efficient screens.Solar screens with openings having horizontal aspect ratios were found to be the most effective, while those with vertical aspect ratios were achieved the lowest performance. In the North orientation, since almost all the cases that were tested in this research provided acceptable daylighting performance, the designer now have a variety of options to choose from. Preference should be given to screen openings of horizontal aspect ratios, especially the 12:1 and 18:1 (H:V) screens that achieved the best performance where 92% of the space was " daylit" in comparison with only 53

On the Solar oblateness

International Nuclear Information System (INIS)

Kislik, M.D.

1983-01-01

Limits for the magnitude of Solar oblateness under the assumption that the Sun is rotating as a rigid body with the velocity of sideric rotation of the equator points have been determined. It is demonstrated that for the present there is no necessity to take into accoUnt Solar oblateness when making the interior planets movement theories

Measurement of the solar neutrino capture rate with gallium metal, part III

International Nuclear Information System (INIS)

Elliott, Steven Ray

2008-01-01

The Russian-American experiment SAGE began to measure the solar neutrino capture rate with a target of gallium metal in December 1989. Measurements have continued with only a few brief interruptions since that time. In this article we present the experimental improvements in SAGE since its last published data summary in December 2001. Assuming the solar neutrino production rate was constant during the period of data collection, combined analysis of 168 extractions through December 2007 gives a capture rate of solar neutrinos with energy more than 233 keY of 65.4 +3.1 3.0 (stat) +2.6 -2.8 (syst) SNU. The weighted average of the results of all three Ga solar neUlrino experiments, SAGE, Gallex, and GNO, is now 66.1 ± 3.1 SNU, where statistical and systematic uncertainties have been combined in quadrature. During the recent period of data collection a new test of SAGE was made with a reactor-produced 37 Ar neutrino source. The ratio of observed to calculated rates in this experiment, combined with the measured rates in the three prior 51 Cr neutrino-source experiments with Ga, is 0.88 ± 0.05. A probable explanation for this low result is that the cross section for neutrino capture by the two lowest-lying excited states in 71 Ge has been overestimated. If we assume these cross sections are zero, then the standard solar model including neutrino oscillations predicts a total capture rate in Ga in the range of 63--67 SNU with an uncertainly of about 5%, in good agreement with experiment. We derive the current value of the pp neutrino flux produced in the Sun to be φ · pp = (6.1 ± 0.8) x 10 10 /(cm 2 s), which agrees well with the flux predicted by the standard solar model. Finally, we make several tests and show that the data are consistent with the assumption that the solar neutrino production rate is constant in time.

A cone-like enhancement of polar solar corona plasma and its influence on heliospheric particles

Science.gov (United States)

Grzedzielski, Stan; Sokół, Justyna M.

2017-04-01

We will present results of the study of the properties of the solar wind plasma due to rotation of the polar solar corona. We focus in our study on the solar minimum conditions, when the polar coronal holes are well formed and the magnetic field in the solar polar corona exhibit almost regular "ray-like" structure. The solar rotation twists the magnetic field lines of the expanding fast polar solar wind and the resulting toroidal component of the field induces a force directed towards the rotation axis. This phenomenon is tantamount to a (weak) zeta pinch, known also in other astrophysical contexts (e.g. like in AGN jets). The pinch compresses the polar solar corona plasma and forms a cone-like enhancement of the solar wind density aligned with the rotation axis in the spherically symmetric case. The effect is likely very dynamic due to fast changing conditions in the solar corona, however in the study presented here, we assume a time independent description to get an order-of-magnitude estimate. The weak pinch is treated as a first-order perturbation to the zeroth-order radial flow. Following the assumptions based on the available knowledge about the plasma properties in the polar solar corona we estimated the most typical density enhancements. The cone like structure may extend as far from the Sun as tens of AU and thus will influence the heliospheric particles inside the heliosphere. An increase of the solar wind density in the polar region may be related with a decrease of the solar wind speed. Such changes of the solar wind plasma at high latitudes may modify the charge-exchange and electron impact ionization rates of heliospheric particles in interplanetary space. We will present their influence on the interstellar neutral gas and energetic neutral atoms observed by IBEX.

Energy Cascade Rate in Compressible Fast and Slow Solar Wind Turbulence

Energy Technology Data Exchange (ETDEWEB)

Hadid, L. Z.; Sahraoui, F.; Galtier, S., E-mail: lina.hadid@lpp.polytechnique.fr [LPP, CNRS, Ecole Polytechnique, UPMC Univ Paris 06, Univ. Paris-Sud, Observatoire de Paris, Université Paris-Saclay, Sorbonne Universités, PSL Research University, F-91128 Palaiseau (France)

2017-03-20

Estimation of the energy cascade rate in the inertial range of solar wind turbulence has been done so far mostly within incompressible magnetohydrodynamics (MHD) theory. Here, we go beyond that approximation to include plasma compressibility using a reduced form of a recently derived exact law for compressible, isothermal MHD turbulence. Using in situ data from the THEMIS / ARTEMIS spacecraft in the fast and slow solar wind, we investigate in detail the role of the compressible fluctuations in modifying the energy cascade rate with respect to the prediction of the incompressible MHD model. In particular, we found that the energy cascade rate (1) is amplified particularly in the slow solar wind; (2) exhibits weaker fluctuations in spatial scales, which leads to a broader inertial range than the previous reported ones; (3) has a power-law scaling with the turbulent Mach number; (4) has a lower level of spatial anisotropy. Other features of solar wind turbulence are discussed along with their comparison with previous studies that used incompressible or heuristic (nonexact) compressible MHD models.

Energy Cascade Rate in Compressible Fast and Slow Solar Wind Turbulence

International Nuclear Information System (INIS)

Hadid, L. Z.; Sahraoui, F.; Galtier, S.

2017-01-01

Estimation of the energy cascade rate in the inertial range of solar wind turbulence has been done so far mostly within incompressible magnetohydrodynamics (MHD) theory. Here, we go beyond that approximation to include plasma compressibility using a reduced form of a recently derived exact law for compressible, isothermal MHD turbulence. Using in situ data from the THEMIS / ARTEMIS spacecraft in the fast and slow solar wind, we investigate in detail the role of the compressible fluctuations in modifying the energy cascade rate with respect to the prediction of the incompressible MHD model. In particular, we found that the energy cascade rate (1) is amplified particularly in the slow solar wind; (2) exhibits weaker fluctuations in spatial scales, which leads to a broader inertial range than the previous reported ones; (3) has a power-law scaling with the turbulent Mach number; (4) has a lower level of spatial anisotropy. Other features of solar wind turbulence are discussed along with their comparison with previous studies that used incompressible or heuristic (nonexact) compressible MHD models.

An equatorial coronal hole at solar minimum

Science.gov (United States)

Bromage, B. J. I.; DelZanna, G.; DeForest, C.; Thompson, B.; Clegg, J. R.

1997-01-01

The large transequatorial coronal hole that was observed in the solar corona at the end of August 1996 is presented. It consists of a north polar coronal hole called the 'elephant's trunk or tusk'. The observations of this coronal hole were carried out with the coronal diagnostic spectrometer onboard the Solar and Heliospheric Observatory (SOHO). The magnetic field associated with the equatorial coronal hole is strongly connected to that of the active region at its base, resulting in the two features rotating at almost the same rate.

Helioseismology and the Solar Interior Dynamics

Indian Academy of Sciences (India)

tribpo

gives information on the internal solar rotation: while differential rotation exists in the ... show that lithium has been depleted by a factor of about 140 compared to the proto- solar value ... 2.1 Theory of element settling in the Sun and the stars.

Long-term changes in the rotation of the Earth: 700 B.C. to A.D. 1980

International Nuclear Information System (INIS)

Stephenson, F.R.

1984-01-01

Occultations of stars by the Moon, and solar and lunar eclipses are analysed for variations in the Earth's rotation over the past 2700 years. Although tidal braking provides the dominant, long-term torque, it is found that the rate of rotation does not decrease uniformly as would be expected if tidal friction were the only mechanism affecting the Earth's rotation. There are also non-tidal changes present that vary on timescales ranging from decades to millennia. The magnitudinal and temporal behaviour of these non-tidal variations are evaluated in this paper. (author)

Solar radiation increases suicide rate after adjusting for other climate factors in South Korea.

Science.gov (United States)

Jee, Hee-Jung; Cho, Chul-Hyun; Lee, Yu Jin; Choi, Nari; An, Hyonggin; Lee, Heon-Jeong

2017-03-01

Previous studies have indicated that suicide rates have significant seasonal variations. There is seasonal discordance between temperature and solar radiation due to the monsoon season in South Korea. We investigated the seasonality of suicide and assessed its association with climate variables in South Korea. Suicide rates were obtained from the National Statistical Office of South Korea, and climatic data were obtained from the Korea Meteorological Administration for the period of 1992-2010. We conducted analyses using a generalized additive model (GAM). First, we explored the seasonality of suicide and climate variables such as mean temperature, daily temperature range, solar radiation, and relative humidity. Next, we identified confounding climate variables associated with suicide rate. To estimate the adjusted effect of solar radiation on the suicide rate, we investigated the confounding variables using a multivariable GAM. Suicide rate showed seasonality with a pattern similar to that of solar radiation. We found that the suicide rate increased 1.008 times when solar radiation increased by 1 MJ/m 2 after adjusting for other confounding climate factors (P Solar radiation has a significant linear relationship with suicide after adjusting for region, other climate variables, and time trends. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Estimation of daily flow rate of photovoltaic water pumping systems using solar radiation data

Directory of Open Access Journals (Sweden)

M. Benghanem

2018-03-01

Full Text Available This paper presents a simple model which allows us to contribute in the studies of photovoltaic (PV water pumping systems sizing. The nonlinear relation between water flow rate and solar power has been obtained experimentally in a first step and then used for performance prediction. The model proposed enables us to simulate the water flow rate using solar radiation data for different heads (50 m, 60 m, 70 m and 80 m and for 8S × 3P PV array configuration. The experimental data are obtained with our pumping test facility located at Madinah site (Saudi Arabia. The performances are calculated using the measured solar radiation data of different locations in Saudi Arabia. Knowing the solar radiation data, we have estimated with a good precision the water flow rate Q in five locations (Al-Jouf, Solar Village, AL-Ahsa, Madinah and Gizan in Saudi Arabia. The flow rate Q increases with the increase of pump power for different heads following the nonlinear model proposed. Keywords: Photovoltaic water pumping system, Solar radiation data, Simulation, Flow rate

Factors affecting healing rates after arthroscopic double-row rotator cuff repair.

Science.gov (United States)

Tashjian, Robert Z; Hollins, Anthony M; Kim, Hyun-Min; Teefey, Sharlene A; Middleton, William D; Steger-May, Karen; Galatz, Leesa M; Yamaguchi, Ken

2010-12-01

Double-row arthroscopic rotator cuff repairs were developed to improve initial biomechanical strength of repairs to improve healing rates. Despite biomechanical improvements, failure of healing remains a clinical problem. To evaluate the anatomical results after double-row arthroscopic rotator cuff repair with ultrasound to determine postoperative repair integrity and the effect of various factors on tendon healing. Case series; Level of evidence, 4. Forty-eight patients (49 shoulders) who had a complete arthroscopic rotator cuff repair (double-row technique) were evaluated with ultrasound at a minimum of 6 months after surgery. Outcome was evaluated at a minimum of 1-year follow-up with standardized history and physical examination, visual analog scale for pain, active forward elevation, and preoperative and postoperative shoulder scores according to the system of the American Shoulder and Elbow Surgeons and the Simple Shoulder Test. Quantitative strength was measured postoperatively. Ultrasound and physical examinations were performed at a minimum of 6 months after surgery (mean, 16 months; range, 6 to 36 months) and outcome questionnaire evaluations at a minimum of 12 months after surgery (mean, 29 months; range, 12 to 55 months). Of 49 repairs, 25 (51%) were healed. Healing rates were 67% in single-tendon tears (16 of 24 shoulders) and 36% in multitendon tears (9 of 25 shoulders). Older age and longer duration of follow-up were correlated with poorer tendon healing (P repair (P rotator cuff repair. The biological limitation at the repair site, as reflected by the effects of age on healing, appears to be the most important factor influencing tendon healing, even after maximizing repair biomechanical strength with a double-row construct.

Analysis and Compensation of Modulation Angular Rate Error Based on Missile-Borne Rotation Semi-Strapdown Inertial Navigation System

Directory of Open Access Journals (Sweden)

Jiayu Zhang

2018-05-01

Full Text Available The Semi-Strapdown Inertial Navigation System (SSINS provides a new solution to attitude measurement of a high-speed rotating missile. However, micro-electro-mechanical-systems (MEMS inertial measurement unit (MIMU outputs are corrupted by significant sensor errors. In order to improve the navigation precision, a rotation modulation technology method called Rotation Semi-Strapdown Inertial Navigation System (RSSINS is introduced into SINS. In fact, the stability of the modulation angular rate is difficult to achieve in a high-speed rotation environment. The changing rotary angular rate has an impact on the inertial sensor error self-compensation. In this paper, the influence of modulation angular rate error, including acceleration-deceleration process, and instability of the angular rate on the navigation accuracy of RSSINS is deduced and the error characteristics of the reciprocating rotation scheme are analyzed. A new compensation method is proposed to remove or reduce sensor errors so as to make it possible to maintain high precision autonomous navigation performance by MIMU when there is no external aid. Experiments have been carried out to validate the performance of the method. In addition, the proposed method is applicable for modulation angular rate error compensation under various dynamic conditions.

Mean-field theory of differential rotation in density stratified turbulent convection

Science.gov (United States)

Rogachevskii, I.

2018-04-01

A mean-field theory of differential rotation in a density stratified turbulent convection has been developed. This theory is based on the combined effects of the turbulent heat flux and anisotropy of turbulent convection on the Reynolds stress. A coupled system of dynamical budget equations consisting in the equations for the Reynolds stress, the entropy fluctuations and the turbulent heat flux has been solved. To close the system of these equations, the spectral approach, which is valid for large Reynolds and Péclet numbers, has been applied. The adopted model of the background turbulent convection takes into account an increase of the turbulence anisotropy and a decrease of the turbulent correlation time with the rotation rate. This theory yields the radial profile of the differential rotation which is in agreement with that for the solar differential rotation.

Modeling the Solar Convective Dynamo and Emerging Flux

Science.gov (United States)

Fan, Y.

2017-12-01

Significant advances have been made in recent years in global-scale fully dynamic three-dimensional convective dynamo simulations of the solar/stellar convective envelopes to reproduce some of the basic features of the Sun's large-scale cyclic magnetic field. It is found that the presence of the dynamo-generated magnetic fields plays an important role for the maintenance of the solar differential rotation, without which the differential rotation tends to become anti-solar (with a faster rotating pole instead of the observed faster rotation at the equator). Convective dynamo simulations are also found to produce emergence of coherent super-equipartition toroidal flux bundles with a statistically significant mean tilt angle that is consistent with the mean tilt of solar active regions. The emerging flux bundles are sheared by the giant cell convection into a forward leaning loop shape with its leading side (in the direction of rotation) pushed closer to the strong downflow lanes. Such asymmetric emerging flux pattern may lead to the observed asymmetric properties of solar active regions.

Pump--probe measurements of state-to-state rotational energy transfer rates in N2 (v=1)

International Nuclear Information System (INIS)

Sitz, G.O.; Farrow, R.L.

1990-01-01

We report direct measurements of the state-to-state rotational energy transfer rates for N 2 (υ=1) at 298 K. Stimulated Raman pumping of Q-branch (υ=1 left-arrow 0) transitions is used to prepare a selected rotational state of N 2 in the υ=1 state. After allowing an appropriate time interval for collisions to occur, 2+2 resonance-enhanced multiphoton ionization is used (through the a 1 Π g left-arrow X 1 Σ + g transition) to detect the relative population of the pumped level and other levels to which rotational energy transfer has occurred. We have performed a series of measurements in which a single even rotational level (J i =0--14) is excited and the time-dependent level populations are recorded at three or more delay times. This data set is then globally fit to determine the best set of state-to-state rate constants. The fitting procedure does not place any constraints (such as an exponential gap law) on the J or energy dependence of the rates. We compare our measurements and best-fit rates with results predicted from phenomenological rate models and from a semiclassical scattering calculation of Koszykowski et al. [J. Phys. Chem. 91, 41 (1987)]. Excellent agreement is obtained with two of the models and with the scattering calculation. We also test the validity of the energy-corrected sudden (ECS) scaling theory for N 2 by using our experimental transfer rates as basis rates (J=L→0), finding that the ECS scaling expressions accurately predict the remaining rates

Estimation of daily flow rate of photovoltaic water pumping systems using solar radiation data

Science.gov (United States)

Benghanem, M.; Daffallah, K. O.; Almohammedi, A.

2018-03-01

This paper presents a simple model which allows us to contribute in the studies of photovoltaic (PV) water pumping systems sizing. The nonlinear relation between water flow rate and solar power has been obtained experimentally in a first step and then used for performance prediction. The model proposed enables us to simulate the water flow rate using solar radiation data for different heads (50 m, 60 m, 70 m and 80 m) and for 8S × 3P PV array configuration. The experimental data are obtained with our pumping test facility located at Madinah site (Saudi Arabia). The performances are calculated using the measured solar radiation data of different locations in Saudi Arabia. Knowing the solar radiation data, we have estimated with a good precision the water flow rate Q in five locations (Al-Jouf, Solar Village, AL-Ahsa, Madinah and Gizan) in Saudi Arabia. The flow rate Q increases with the increase of pump power for different heads following the nonlinear model proposed.

Convection and magnetism of solar-type stars (G and K)

International Nuclear Information System (INIS)

Do-Cao, Olivier Long

2013-01-01

This thesis aims at understanding the internal dynamics of solar-type stars and the origin of their magnetism. We will explore the complex nonlinear interactions between convection, rotation and magnetism conducting both 2D (STELEM code) and 3D (ASH code) numerical simulations. This dual approach will unveil the mechanisms and key parameters behind those physical processes. While the Sun has played a central role in previous studies, this work extends our knowledge to G and K stars. This manuscript is divided into 4 parts. The first one introduces the concepts behind internal stellar dynamics, and emphasizes the dynamo effect. Accurate observations of the Sun will be compared to stellar data, allowing us to determine what is specific to the Sun and what is generic for all stars. The second part reports the results obtained with the 2D STELEM code. This code allows us to study the generation and evolution of the large scale magnetic fields on a timescale comparable to the solar cycle period (11 years), giving us insight into the underlying dynamo processes at work. We show that the current solar models cannot reproduce the observations, when applied to rapidly rotating stars, unless we consider a turbulent pumping mechanism under specific conditions. Then, we have improved these kinematic models by taking into account the large scale magnetic field feedback on the longitudinal velocity component, called the Malkus Proctor effect. The models are now able to reproduce the solar torsional oscillations and can predict how their properties evolve with rotation rate. The third part focuses on 3D numerical simulations running on massively parallel supercomputers, using the ASH code. In contrast with the previously described code, ASH explicitly resolves the full MHD equations. We have studied (hydrodynamically) how the convective properties of G and K stars change as function of mass and rotation rate, first by considering the convective envelope alone, then by taking into

A High Rated Solar Water Distillation Unit for Solar Homes

Directory of Open Access Journals (Sweden)

Abhishek Saxena

2016-01-01

Full Text Available India is presently focusing on complete utilization of solar energy and saving fossil fuels, which are limited. Various solar energy systems like solar cookers, solar water heaters, solar lanterns, solar PV lights, and solar lamps are continuously availing by the people of India at a low cost and on good subsidies. Apart from this, India is a solar energy promising country with a good number of solar homes (carrying solar energy systems in its various locations. The present paper focuses on a unique combination of solar dish cooker (SDC and solar water heater (SWH to produce distilled water with a high distillate and a high daily productivity. The procedure has been discussed on the basis of experimental testing to produce distilled water by combining an evacuated type SWH and a SDC. Experimentation has been carried out in MIT, Moradabad (longitude, 28.83°N, and latitude, 78.78°E by developing the same experimental setup on behalf of solar homes. The daily productivity of distilled water was found around 3.66 litres per day in full sunshine hours for an approximated pH value of 7.7 and a ppm value of 21. The payback period (PBP has been estimated around 1.16 years of the present system.

Precision Measurement of the Beryllium-7 Solar Neutrino Interaction Rate in Borexino

Science.gov (United States)

Saldanha, Richard Nigel

Solar neutrinos, since their first detection nearly forty years ago, have revealed valuable information regarding the source of energy production in the Sun, and have demonstrated that neutrino oscillations are well described by the Large Mixing Angle (LMA) oscillation parameters with matter interactions due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. This thesis presents a precision measurement of the 7Be solar neutrino interaction rate within Borexino, an underground liquid scintillator detector that is designed to measure solar neutrino interactions through neutrino-electron elastic scattering. The thesis includes a detailed description of the analysis techniques developed and used for this measurement as well as an evaluation of the relevant systematic uncertainties that affect the precision of the result. The rate of neutrino-electron elastic scattering from 0.862 MeV 7Be neutrinos is determined to be 45.4 +/- 1.6 (stat) +/- 1.5 (sys) counts/day/100 ton. Due to extensive detector calibrations and improved analysis methods, the systematic uncertainty in the interaction rate has been reduced by more than a factor of two from the previous evaluation. In the no-oscillation hypothesis, the interaction rate corresponds to a 0.862 MeV 7Be electron neutrino flux of (2.75 +/- 0.13) x 10 9 cm-2 sec-1. Including the predicted neutrino flux from the Standard Solar Model yields an electron neutrino survival probability of Pee 0.51 +/- 0.07 and rules out the no-oscillation hypothesis at 5.1sigma The LMA-MSW neutrino oscillation model predicts a transition in the solar Pee value between low ( 10 MeV) energies which has not yet been experimentally confirmed. This result, in conjunction with the Standard Solar Model, represents the most precise measurement of the electron neutrino survival probability for solar neutrinos at sub-MeV energies.

Variations in Solar Parameters and Cosmic Rays with Solar Magnetic Polarity

Energy Technology Data Exchange (ETDEWEB)

Oh, S. [Department of Earth Science Education, Chonnam National University, Gwangju, 61186 (Korea, Republic of); Yi, Y., E-mail: suyeonoh@jnu.ac.kr [Department of Astronomy, Space Science and Geology, Chungnam National University, Daejeon, 34134 (Korea, Republic of)

2017-05-01

The sunspot number varies with the 11-year Schwabe cycle, and the solar magnetic polarity reverses every 11 years approximately at the solar maximum. Because of polarity reversal, the difference between odd and even solar cycles is seen in solar activity. In this study, we create the mean solar cycle expressed by phase using the monthly sunspot number for all solar cycles 1–23. We also generate the mean solar cycle for sunspot area, solar radio flux, and cosmic ray flux within the allowance of observational range. The mean solar cycle has one large peak at solar maximum for odd solar cycles and two small peaks for most even solar cycles. The odd and even solar cycles have the statistical difference in value and shape at a confidence level of at least 98%. For solar cycles 19–23, the second peak in the even solar cycle is larger than the first peak. This result is consistent with the frequent solar events during the declining phase after the solar maximum. The difference between odd and even solar cycles can be explained by a combined model of polarity reversal and solar rotation. In the positive/negative polarity, the polar magnetic field introduces angular momentum in the same/opposite direction as/to the solar rotation. Thus the addition/subtraction of angular momentum can increase/decrease the motion of plasma to support the formation of sunspots. Since the polarity reverses at the solar maximum, the opposite phenomenon occurs in the declining phase.

Increasing age and tear size reduce rotator cuff repair healing rate at 1 year.

Science.gov (United States)

Rashid, Mustafa S; Cooper, Cushla; Cook, Jonathan; Cooper, David; Dakin, Stephanie G; Snelling, Sarah; Carr, Andrew J

2017-12-01

Background and purpose - There is a need to understand the reasons why a high proportion of rotator cuff repairs fail to heal. Using data from a large randomized clinical trial, we evaluated age and tear size as risk factors for failure of rotator cuff repair. Patients and methods - Between 2007 and 2014, 65 surgeons from 47 hospitals in the National Health Service (NHS) recruited 447 patients with atraumatic rotator cuff tendon tears to the United Kingdom Rotator Cuff Trial (UKUFF) and 256 underwent rotator cuff repair. Cuff integrity was assessed by imaging in 217 patients, at 12 months post-operation. Logistic regression analysis was used to determine the influence of age and intra-operative tear size on healing. Hand dominance, sex, and previous steroid injections were controlled for. Results - The overall healing rate was 122/217 (56%) at 12 months. Healing rate decreased with increasing tear size (small tears 66%, medium tears 68%, large tears 47%, and massive tears 27% healed). The mean age of patients with a healed repair was 61 years compared with 64 years for those with a non-healed repair. Mean age increased with larger tear sizes (small tears 59 years, medium tears 62 years, large tears 64 years, and massive tears 66 years). Increasing age was an independent factor that negatively influenced healing, even after controlling for tear size. Only massive tears were an independent predictor of non-healing, after controlling for age. Interpretation - Although increasing age and larger tear size are both risks for failure of rotator cuff repair healing, age is the dominant risk factor.

A parametric study of a solar calcinator using computational fluid dynamics

International Nuclear Information System (INIS)

Fidaros, D.K.; Baxevanou, C.A.; Vlachos, N.S.

2007-01-01

In this work a horizontal rotating solar calcinator is studied numerically using computational fluid dynamics. The specific solar reactor is a 10 kW model designed and used for efficiency studies. The numerical model is based on the solution of the Navier-Stokes equations for the gas flow, and on Lagrangean dynamics for the discrete particles. All necessary mathematical models were developed and incorporated into a computational fluid dynamics model with the influence of turbulence simulated by a two-equation (RNG k-ε) model. The efficiency of the reactor was calculated for different thermal inputs, feed rates, rotational speeds and particle diameters. The numerically computed degrees of calcination compared well with equivalent experimental results

Investigations on efficiencies of HT solar collectors for different flow rates and collector tilts

DEFF Research Database (Denmark)

Chen, Ziqian; Perers, Bengt; Furbo, Simon

2013-01-01

Two HT solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one solar collector is equipped with an ETFE foil between the abso......Two HT solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one solar collector is equipped with an ETFE foil between...... the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates and tilt. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rates are obtained. The calculated efficiencies are in good...

M Dwarf Rotation from the K2 Young Clusters to the Field. I. A Mass-Rotation Correlation at 10 Myr

Science.gov (United States)

Somers, Garrett; Stauffer, John; Rebull, Luisa; Cody, Ann Marie; Pinsonneault, Marc

2017-12-01

Recent observations of the low-mass (0.1-0.6 {M}⊙ ) rotation distributions of the Pleiades and Praesepe clusters have revealed a ubiquitous correlation between mass and rotation, such that late M dwarfs rotate an order-of-magnitude faster than early M dwarfs. In this paper, we demonstrate that this mass-rotation correlation is present in the 10 Myr Upper Scorpius association, as revealed by new K2 rotation measurements. Using rotational evolution models, we show that the low-mass rotation distribution of the 125 Myr Pleiades cluster can only be produced if it hosted an equally strong mass-rotation correlation at 10 Myr. This suggests that physical processes important in the early pre-main sequence (PMS; star formation, accretion, disk-locking) are primarily responsible for the M dwarf rotation morphology, and not quirks of later angular momentum (AM) evolution. Such early mass trends must be taken into account when constructing initial conditions for future studies of stellar rotation. Finally, we show that the average M star loses ˜25%-40% of its AM between 10 and 125 Myr, a figure accurately and generically predicted by modern solar-calibrated wind models. Their success rules out a lossless PMS and validates the extrapolation of magnetic wind laws designed for solar-type stars to the low-mass regime at early times.

Anelastic Models of Fully-Convective Stars: Differential Rotation, Meridional Circulation and Residual Entropy

Science.gov (United States)

Sainsbury-Martinez, Felix; Browning, Matthew; Miesch, Mark; Featherstone, Nicholas A.

2018-01-01

Low-Mass stars are typically fully convective, and as such their dynamics may differ significantly from sun-like stars. Here we present a series of 3D anelastic HD and MHD simulations of fully convective stars, designed to investigate how the meridional circulation, the differential rotation, and residual entropy are affected by both varying stellar parameters, such as the luminosity or the rotation rate, and by the presence of a magnetic field. We also investigate, more specifically, a theoretical model in which isorotation contours and residual entropy (σ‧ = σ ‑ σ(r)) are intrinsically linked via the thermal wind equation (as proposed in the Solar context by Balbus in 2009). We have selected our simulation parameters in such as way as to span the transition between Solar-like differential rotation (fast equator + slow poles) and ‘anti-Solar’ differential rotation (slow equator + fast poles), as characterised by the convective Rossby number and △Ω. We illustrate the transition from single-celled to multi-celled MC profiles, and from positive to negative latitudinal entropy gradients. We show that an extrapolation involving both TWB and the σ‧/Ω link provides a reasonable estimate for the interior profile of our fully convective stars. Finally, we also present a selection of MHD simulations which exhibit an almost unsuppressed differential rotation profile, with energy balances remaining dominated by kinetic components.

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.

Vibration measurements of the Daniel K. Inouye Solar Telescope mount, Coudé rotator, and enclosure assemblies

Science.gov (United States)

McBride, William R.; McBride, Daniel R.

2016-08-01

The Daniel K. Inouye Solar Telescope (DKIST) will be the largest solar telescope in the world, with a 4-meter off-axis primary mirror and 16 meter rotating Coudé laboratory within the telescope pier. The off-axis design requires a mount similar to an 8-meter on-axis telescope. Both the telescope mount and the Coudé laboratory utilize a roller bearing technology in place of the more commonly used hydrostatic bearings. The telescope enclosure utilizes a crawler mechanism for the altitude axis. As these mechanisms have not previously been used in a telescope, understanding the vibration characteristics and the potential impact on the telescope image is important. This paper presents the methodology used to perform jitter measurements of the enclosure and the mount bearings and servo system in a high-noise environment utilizing seismic accelerometers and high dynamic-range data acquisition equipment, along with digital signal processing (DSP) techniques. Data acquisition and signal processing were implemented in MATLAB. In the factory acceptance testing of the telescope mount, multiple accelerometers were strategically located to capture the six axes-of-motion of the primary and secondary mirror dummies. The optical sensitivity analysis was used to map these mirror mount displacements and rotations into units of image motion on the focal plane. Similarly, tests were done with the Coudé rotator, treating the entire rotating instrument lab as a rigid body. Testing was performed by recording accelerometer data while the telescope control system performed tracking operations typical of various observing scenarios. The analysis of the accelerometer data utilized noise-averaging fast Fourier transform (FFT) routines, spectrograms, and periodograms. To achieve adequate dynamic range at frequencies as low as 3Hz, the use of special filters and advanced windowing functions were necessary. Numerous identical automated tests were compared to identify and select the data sets

Does nitrogen fertilizer application rate to corn affect nitrous oxide emissions from the rotated soybean crop?

Science.gov (United States)

Iqbal, Javed; Mitchell, David C; Barker, Daniel W; Miguez, Fernando; Sawyer, John E; Pantoja, Jose; Castellano, Michael J

2015-05-01

Little information exists on the potential for N fertilizer application to corn ( L.) to affect NO emissions during subsequent unfertilized crops in a rotation. To determine if N fertilizer application to corn affects NO emissions during subsequent crops in rotation, we measured NO emissions for 3 yr (2011-2013) in an Iowa, corn-soybean [ (L.) Merr.] rotation with three N fertilizer rates applied to corn (0 kg N ha, the recommended rate of 135 kg N ha, and a high rate of 225 kg N ha); soybean received no N fertilizer. We further investigated the potential for a winter cereal rye ( L.) cover crop to interact with N fertilizer rate to affect NO emissions from both crops. The cover crop did not consistently affect NO emissions. Across all years and irrespective of cover crop, N fertilizer application above the recommended rate resulted in a 16% increase in mean NO flux rate during the corn phase of the rotation. In 2 of the 3 yr, N fertilizer application to corn (0-225 kg N ha) did not affect mean NO flux rates from the subsequent unfertilized soybean crop. However, in 1 yr after a drought, mean NO flux rates from the soybean crops that received 135 and 225 kg N ha N application in the corn year were 35 and 70% higher than those from the soybean crop that received no N application in the corn year. Our results are consistent with previous studies demonstrating that cover crop effects on NO emissions are not easily generalizable. When N fertilizer affects NO emissions during a subsequent unfertilized crop, it will be important to determine if total fertilizer-induced NO emissions are altered or only spread across a greater period of time. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Differential rotation and the solar dynamo

International Nuclear Information System (INIS)

Stix, M.

1976-01-01

A number of numerical models for the generation of mean magnetic fields is examined and the fields are compared with the mean field of the Sun. In particular, αω-dynamos, which are based on differential rotation and cyclonic turbulence, are studied in the case of cylindrical surfaces of isorotation. Such dynamos have an oscillatory antisymmetric field as the most easily excited mode. Only models with an angular velocity which increases with increasing depth appear to be compatible with observations. A search for oscillatory ω x j-dynamos, where the α-effect is replaced by a different mean electric field perpendicular to the rotation vector ω and the mean current density j is also made. Oscillatory modes do exist for models with radial shear. Their migration is equatorwards for inwards increasing angular velocity. (orig./BJ) [de

Perioperative Serum Lipid Status and Statin Use Affect the Revision Surgery Rate After Arthroscopic Rotator Cuff Repair.

Science.gov (United States)

Cancienne, Jourdan M; Brockmeier, Stephen F; Rodeo, Scott A; Werner, Brian C

2017-11-01

Recent animal studies have demonstrated that hyperlipidemia is associated with poor tendon-bone healing after rotator cuff repair; however, these findings have not been substantiated in human studies. To examine any association between hyperlipidemia and the failure of arthroscopic rotator cuff repair requiring revision surgery and to investigate whether the use of statin lipid-lowering agents had any influence on observed associations. Cohort study; Level of evidence, 3. From a national insurance database, patients who underwent arthroscopic rotator cuff repair with perioperative lipid levels (total cholesterol, low-density lipoprotein [LDL], and triglycerides) recorded were reviewed. For each lipid test, patients were stratified into normal, moderate, and high groups based on published standards. For the total cholesterol and LDL cohorts, a subgroup analysis of patients stratified by statin use was performed. The primary outcome measure was ipsilateral revision rotator cuff surgery, including revision repair or debridement. A logistic regression analysis controlling for patient demographics and comorbidities was utilized for comparison. There were 30,638 patients included in the study. The rate of revision rotator cuff surgery was significantly increased in patients with moderate (odds ratio [OR], 1.20; 95% CI, 1.03-1.40; P = .022) and high total cholesterol levels (OR, 1.36; 95% CI, 1.10-1.55; P = .006) compared with patients with normal total cholesterol levels perioperatively. Within each of these groups, patients without statin use had significantly higher rates of revision surgery, while those with statin prescriptions did not. The absolute risk reduction for statin use ranged from 0.24% to 1.87% when stratified by the total cholesterol level, yielding a number needed to treat from 54 to 408 patients. The rate of revision surgery was significantly increased in patients with moderate (OR, 1.24; 95% CI, 1.10-1.41; P = .001) and high LDL levels (OR, 1.46; 95

Rotational Modulation and Activity Cycles at Rotational Extremes: 25 yrs of NURO Photometry for HII 1883

Science.gov (United States)

Milingo, Jackie; Saar, Steven; Marschall, Laurence

2018-01-01

We present a 25 yr compilation of V-band differential photometry for the Pleiades K dwarf HII 1883 (V660 Tau). HII 1883 has a rotational period of ~ 0.24 d and displays significant rotational modulation due to non-uniform surface brightness or "starspots". Preliminary work yields a cycle period of ~ 9 yrs and rotational shear (ΔP_rot/) considerably less than solar. HII 1883 is one of the fastest rotating single stars with a known cycle. With additional data available we compare newly determined P_cyc and ΔP_rot/ values with those of other stars, putting HII 1883 into the broader context of dynamo properties in single cool dwarfs.

Relation between radio luminosity and rotation for late-type stars

International Nuclear Information System (INIS)

Stewart, R.T.; Innis, J.L.; Slee, O.B.; Nelson, G.J.; Wright, A.E.

1988-01-01

A relation is found between peak radio luminosities measured at 8 GHz and the rotational velocity of 51 late-type F, G, and K stars (including the sun). The sample includes both single stars and active components of close binary systems, with equatorial surface velocities ranging from 1 to 100 km/s. A gyrosynchrotron source model originally developed to explain solar microwave bursts could explain the relation. The main parameter depending on rotation rate is the filling factor, i.e., the fraction of the stellar surface and corona occupied by intense magnetic fields. As the rotation speed increases, the scale size of the coronal structures emitting microwave gyrosynchrotron radiation increases, and there is a corresponding increase in the area of the surface covered by intense starspot magnetic fields. However, the peak magnetic field of the starspots probably does not increase significantly above observed sunspot values. 47 references

Chemical evolution with rotating massive star yields - I. The solar neighbourhood and the s-process elements

Science.gov (United States)

Prantzos, N.; Abia, C.; Limongi, M.; Chieffi, A.; Cristallo, S.

2018-05-01

We present a comprehensive study of the abundance evolution of the elements from H to U in the Milky Way halo and local disc. We use a consistent chemical evolution model, metallicity-dependent isotopic yields from low and intermediate mass stars and yields from massive stars which include, for the first time, the combined effect of metallicity, mass loss, and rotation for a large grid of stellar masses and for all stages of stellar evolution. The yields of massive stars are weighted by a metallicity-dependent function of the rotational velocities, constrained by observations as to obtain a primary-like 14N behaviour at low metallicity and to avoid overproduction of s-elements at intermediate metallicities. We show that the Solar system isotopic composition can be reproduced to better than a factor of 2 for isotopes up to the Fe-peak, and at the 10 per cent level for most pure s-isotopes, both light ones (resulting from the weak s-process in rotating massive stars) and the heavy ones (resulting from the main s-process in low and intermediate mass stars). We conclude that the light element primary process (LEPP), invoked to explain the apparent abundance deficiency of the s-elements with A values of ^{12}C/^{13}C in halo red giants, which is rather due to internal processes in those stars.

Transient rotation of photospheric vector magnetic fields associated with a solar flare.

Science.gov (United States)

Xu, Yan; Cao, Wenda; Ahn, Kwangsu; Jing, Ju; Liu, Chang; Chae, Jongchul; Huang, Nengyi; Deng, Na; Gary, Dale E; Wang, Haimin

2018-01-03

As one of the most violent eruptions on the Sun, flares are believed to be powered by magnetic reconnection. The fundamental physics involving the release, transfer, and deposition of energy have been studied extensively. Taking advantage of the unprecedented resolution provided by the 1.6 m Goode Solar Telescope, here, we show a sudden rotation of vector magnetic fields, about 12-20° counterclockwise, associated with a flare. Unlike the permanent changes reported previously, the azimuth-angle change is transient and cospatial/temporal with Hα emission. The measured azimuth angle becomes closer to that in potential fields suggesting untwist of flare loops. The magnetograms were obtained in the near infrared at 1.56 μm, which is minimally affected by flare emission and no intensity profile change was detected. We believe that these transient changes are real and discuss the possible explanations in which the high-energy electron beams or Alfve'n waves play a crucial role.

SOLAR PHOTOIONIZATION RATES FOR INTERSTELLAR NEUTRALS IN THE INNER HELIOSPHERE: H, He, O, AND Ne

Energy Technology Data Exchange (ETDEWEB)

Bochsler, P.; Kucharek, H.; Möbius, E. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States); Bzowski, Maciej; Sokół, Justyna M. [Space Research Center of the Polish Academy of Sciences, Ul. Bartycka 18A, 00-716 Warsaw (Poland); Didkovsky, Leonid; Wieman, Seth, E-mail: bochsler@space.unibe.ch [Space Sciences Center, University of Southern California, Los Angeles, CA 90089-1341 (United States)

2014-01-01

Extreme UV (EUV) spectra from the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED)/Solar EUV Experiment are used to infer photoionization rates in the inner heliosphere. Relating these rates to various proxies describing the solar EUV radiation, we construct a multi-linear model which allows us to extrapolate ionization rates back to periods when no routine measurements of the solar EUV spectral distribution have been available. Such information is important, e.g., for comparing conditions of the interstellar neutral particles in the inner heliosphere at the time of Ulysses/GAS observations with conditions during the more recent observations of the Interstellar Boundary Explorer. From a period of 11 yr when detailed spectra from both TIMED and three proxies—Solar and Heliospheric Observatory/CELIAS/SEM-rates, F10.7 radio flux, and Mg II core-to-wing indices—have been available, we conclude that the simple model is able to reproduce the photoionization rates with an uncertainty of typically 5%.

78 FR 34371 - Centinela Solar Energy, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

Science.gov (United States)

2013-06-07

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-1561-000] Centinela Solar Energy, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for... Centinela Solar Energy, LLC's application for market-based rate authority, with an accompanying rate...

Effect of Rotation Rate on Microstructure and Properties of Friction Stir Welded Joints of Al/Cu Clad Plates

Directory of Open Access Journals (Sweden)

QIAO Ke

2017-10-01

Full Text Available Al/Cu clad plates were joined by friction stir welding (FSW, and the effect of rotation rate on microstructure and mechanical properties of joints was investigated. The results show that the laminar structure of aluminum and copper is generated in the weld. With increase the of rotation rate, the grain sizes of aluminum and copper are increased respectively. The average microhardness of the Al/Cu plates exceeds that of the as-received metal of 33.0 HV, and ultimate tensile strength is 127.21 MPa in the nugget zone when rotation rate is 1180 r/min. The microhardness of copper in the nugget zone is 99.7 HV, reached 82.05% of the microhardness of received metal, and void defect is main reason responsible for the decrease of mechanical properties of joints.

Rates and timing of vertical-axis block rotations across the central Sierra Nevada-Walker Lane transition in the Bodie Hills, California/Nevada

Science.gov (United States)

Rood, Dylan H.; Burbank, Douglas W.; Herman, Scott W.; Bogue, Scott

2011-10-01

We use paleomagnetic data from Tertiary volcanic rocks to address the rates and timing of vertical-axis block rotations across the central Sierra Nevada-Walker Lane transition in the Bodie Hills, California/Nevada. Samples from the Upper Miocene (˜9 Ma) Eureka Valley Tuff suggest clockwise vertical-axis block rotations between NE-striking left-lateral faults in the Bridgeport and Mono Basins. Results in the Bodie Hills suggest clockwise rotations (R ± ΔR, 95% confidence limits) of 74 ± 8° since Early to Middle Miocene (˜12-20 Ma), 42 ± 11° since Late Miocene (˜8-9 Ma), and 14 ± 10° since Pliocene (˜3 Ma) time with no detectable northward translation. The data are compatible with a relatively steady rotation rate of 5 ± 2° Ma-1 (2σ) since the Middle Miocene over the three examined timescales. The average rotation rates have probably not varied by more than a factor of two over time spans equal to half of the total time interval. Our paleomagnetic data suggest that block rotations in the region of the Mina Deflection began prior to Late Miocene time (˜9 Ma), and perhaps since the Middle Miocene if rotation rates were relatively constant. Block rotation in the Bodie Hills is similar in age and long-term average rate to rotations in the Transverse Ranges of southern California associated with early transtensional dextral shear deformation. We speculate that the age of rotations in the Bodie Hills indicates dextral shear and strain accommodation within the central Walker Lane Belt resulting from coupling of the Pacific and North America plates.

False negative rate of syndesmotic injury in pronation-external rotation stage IV ankle fractures

Directory of Open Access Journals (Sweden)

Kwang-Soon Song

2013-01-01

Full Text Available Background: To investigate false negative rate in the diagnosis of diastasis on initial static anteroposterior radiograph and reliability of intraoperative external rotational stress test for detection of concealed disruption of syndesmosis in pronation external rotation (PER stage IV (Lauge-Hansen ankle fractures. Materials and Methods: We prospectively studied 34 PER stage IV ankle fractures between September 2001 and September 2008. Twenty (59% patients show syndesmotic injury on initial anteroposterior radiographs. We performed an intraoperative external rotation stress test in other 14 patients with suspicious PER stage IV ankle fractures, which showed no defined syndesmotic injury on anteroposterior radiographs inspite of a medial malleolar fracture, an oblique fibular fracture above the syndesmosis and fracture of the posterior tubercle of the tibia. Results: All 14 fractures showed different degrees of tibiofibular clear space (TFCS and tibiofibular overlapping (TFO on the external rotation stress test radiograph compared to the initial plain anteroposterior radiograph. It is important to understand the fracture pattern characterstic of PER stage IV ankle fractures even though it appears normal on anteroposterior radiographs, it is to be confirmed for the concealed syndesmotic injury through a routine intraoperative external rotational stress radiograph.

Increasing FSW join strength by optimizing feed rate, rotating speed and pin angle

Science.gov (United States)

Darmadi, Djarot B.; Purnowidodo, Anindito; Siswanto, Eko

2017-10-01

Principally the join in Friction Stir Welding (FSW) is formed due to mechanical bonding. At least there are two factors determines the quality of this join, first is the temperature in the area around the interface and secondly the intense of mixing forces in nugget zone to create the mechanical bonding. The adequate temperature creates good flowability of the nugget zone and an intensive mixing force produces homogeneous strong bonding. Based on those two factors in this research the effects of feed rate, rotating speed and pin angle of the FSW process to the tensile strength of resulted join are studied. The true experimental method was used. Feed rate was varied at 24, 42, 55 and 74 mm/minutes and from the experimental results, it can be concluded that the higher feed rate decreases the tensile strength of weld join and it is believed due to the lower heat embedded in the material. Inversely, the higher rotating speed increases the join’s tensile strength as a result of higher heat embedded in base metal and higher mixing force in the nugget zone. The rotating speed were 1842, 2257 and 2904 RPMs. The pin angle determines the direction of mixing force. With variation of pin angle: 0°, 4°, 8° and 12° the higher pin angle generally increases the tensile strength because of more intensive mixing force. For 12° pin angle the lower tensile strength is found since the force tends to push out the nugget area from the joint gap.

Some properties of the dynamics of the solar convective zone and their consequences on the activity cycle

International Nuclear Information System (INIS)

Ribes, E.

1986-01-01

A large-scale circulation pattern has been detected in the solar convective zone, for the first time. Tracers used to probe the convective layers are newly-born sunspots and long-lived Hsub(α) filaments. The coincidence of the zonal meridional circulation with the magnetic pattern drawn by the Hsub(α) filaments suggests that we are looking at rotating rolls. The direction of rotation is associated with the magnetic polarity. Another result concerns the rotational rate of the deep convective layers. Young spots seem to rotate more rigidly, in contrast with older spots which exhibit a differential rotation similar to the surface rotation. However, the rotational rate exhibits a large dispersion, partly due to young spots located at the site of converging of diverging rolls. This is the consequence of the Coriolis force which decelerates or accelerates the plasma. These results shed a completely new light on problems dealing with the differential rotation, the transport of angular momentum and the dynamo action [fr

Core rotational dynamics and geological events

Science.gov (United States)

Greff-Lefftz; Legros

1999-11-26

A study of Earth's fluid core oscillations induced by lunar-solar tidal forces, together with tidal secular deceleration of Earth's axial rotation, shows that the rotational eigenfrequency of the fluid core and some solar tidal waves were in resonance around 3.0 x 10(9), 1.8 x 10(9), and 3 x 10(8) years ago. The associated viscomagnetic frictional power at the core boundaries may be converted into heat and would destabilize the D" thermal layer, leading to the generation of deep-mantle plumes, and would also increase the temperature at the fluid core boundaries, perturbing the core dynamo process. Such phenomena could account for large-scale episodes of continental crust formation, the generation of flood basalts, and abrupt changes in geomagnetic reversal frequency.

Inertial wave beams and inertial wave modes in a rotating cylinder with time-modulated rotation rate

Science.gov (United States)

Borcia, Ion D.; Ghasemi V., Abouzar; Harlander, Uwe

2014-05-01

Inertial gravity waves play an crucial role in atmospheres, oceans, and the fluid inside of planets and moons. In the atmosphere, the effect of rotation is neglected for small wavelength and the waves bear the character of internal gravity waves. For long waves, the hydrostatic assumption is made which in turn makes the atmosphere inelastic with respect to inertial motion. In contrast, in the Earth's interior, pure inertial waves are considered as an important fundamental part of the motion. Moreover, as the deep ocean is nearly homogeneous, there the inertial gravity waves bear the character of inertial waves. Excited at the oceans surface mainly due to weather systems the waves can propagate downward and influence the deep oceans motion. In the light of the aforesaid it is important to understand better fundamental inertial wave dynamics. We investigate inertial wave modes by experimental and numerical methods. Inertial modes are excited in a fluid filled rotating annulus by modulating the rotation rate of the outer cylinder and the upper and lower lids. This forcing leads to inertial wave beams emitted from the corner regions of the annulus due to periodic motions in the boundary layers (Klein et al., 2013). When the forcing frequency matches with the eigenfrequency of the rotating annulus the beam pattern amplitude is increasing, the beams broaden and mode structures can be observed (Borcia et al., 2013a). The eigenmodes are compared with analytical solutions of the corresponding inviscid problem (Borcia et al, 2013b). In particular for the pressure field a good agreement can be found. However, shear layers related to the excited wave beams are present for all frequencies. This becomes obvious in particular in the experimental visualizations that are done by using Kalliroscope particles, highlighting relative motion in the fluid. Comparing the eigenfrequencies we find that relative to the analytical frequencies, the experimental and numerical ones show a small

Update on a Solar Magnetic Catalog Spanning Four Solar Cycles

Science.gov (United States)

Vargas-Acosta, Juan Pablo; Munoz-Jaramillo, Andres; Vargas Dominguez, Santiago; Werginz, Zachary; DeLuca, Michael D.; Longcope, Dana; Harvey, J. W.; Windmueller, John; Zhang, Jie; Martens, Petrus C.

2017-08-01

Bipolar magnetic regions (BMRs) are the cornerstone of solar cycle propagation, the building blocks that give structure to the solar atmosphere, and the origin of the majority of space weather events. However, in spite of their importance, there is no homogeneous BMR catalog spanning the era of systematic solar magnetic field measurements. Here we present the results of an ongoing project to address this deficiency applying the Bipolar Active Region Detection (BARD) code to magnetograms from the 512 Channel of the Kitt Peak Vaccum Telescope, SOHO/MDI, and SDO/HMI.The BARD code automatically identifies BMRs and tracks them as they are rotated by differential rotation. The output of the automatic detection is supervised by a human observer to correct possible mistakes made by the automatic algorithm (like incorrect pairings and tracking mislabels). Extra passes are made to integrate fragmented regions as well as to balance the flux between BMR polarities. At the moment, our BMR database includes nearly 10,000 unique objects (detected and tracked) belonging to four separate solar cycles (21-24).

Lunar Rotation, Orientation and Science

Science.gov (United States)

Williams, J. G.; Ratcliff, J. T.; Boggs, D. H.

2004-12-01

The Moon is the most familiar example of the many satellites that exhibit synchronous rotation. For the Moon there is Lunar Laser Ranging measurements of tides and three-dimensional rotation variations plus supporting theoretical understanding of both effects. Compared to uniform rotation and precession the lunar rotational variations are up to 1 km, while tidal variations are about 0.1 m. Analysis of the lunar variations in pole direction and rotation about the pole gives moment of inertia differences, third-degree gravity harmonics, tidal Love number k2, tidal dissipation Q vs. frequency, dissipation at the fluid-core/solid-mantle boundary, and emerging evidence for an oblate boundary. The last two indicate a fluid core, but a solid inner core is not ruled out. Four retroreflectors provide very accurate positions on the Moon. The experience with the Moon is a starting point for exploring the tides, rotation and orientation of the other synchronous bodies of the solar system.

Mid-term periodicities and heliospheric modulation of coronal index and solar flare index during solar cycles 22-23

Science.gov (United States)

Singh, Prithvi Raj; Saxena, A. K.; Tiwari, C. M.

2018-04-01

We applied fast Fourier transform techniques and Morlet wavelet transform on the time series data of coronal index, solar flare index, and galactic cosmic ray, for the period 1986-2008, in order to investigate the long- and mid-term periodicities including the Rieger ({˜ }130 to {˜ }190 days), quasi-period ({˜ }200 to {˜ }374 days), and quasi-biennial periodicities ({˜ }1.20 to {˜ }3.27 years) during the combined solar cycles 22-23. We emphasize the fact that a lesser number of periodicities are found in the range of low frequencies, while the higher frequencies show a greater number of periodicities. The rotation rates at the base of convection zone have periods for coronal index of {˜ }1.43 years and for solar flare index of {˜ }1.41 year, and galactic cosmic ray, {˜ }1.35 year, during combined solar cycles 22-23. In relation to these two solar parameters (coronal index and solar flare index), for the solar cycles 22-23, we found that galactic cosmic ray modulation at mid cut-off rigidity (Rc = 2.43GV) is anti-correlated with time-lag of few months.

Effect of flow rate and disc area increment on the efficiency of rotating biological contactor for treating greywater

International Nuclear Information System (INIS)

Pathan, A.A.

2015-01-01

The performance of greywater treatment through RBC (Rotating Biological Contactor) is related to many factors including rotational speed of disc, surface area of the media, thickness of biological film; quality and flow rate of influent. The plastic media provides surface for biological slime. The slime is rotated alternatively into the settled wastewater and then into atmosphere to provide aerobic conditions for the microorganisms. In this study the performance of RBC is investigated at different flow rates and disk areas of media by introducing additional discs on the shaft of RBC. Initially efficiency of the RBC was observed on six flow rates at the disc area of 9.78m/sup 2/. Furthermore optimized three flow rates were used to augment the disk area. The efficiency of RBC system was improved significantly at disk area of 11.76m/sup 2/ and flow rate of 20 L/h. Under these conditions the removal of BOD5 (Biochemical Oxygen Demand) COD (Chemical Oxygen Demand) and TSS (Total Suspended Solid) was observed 83, 57 and 90% respectively. (author)

A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5

Science.gov (United States)

Hsu, Juno; Prather, Michael J.; Cameron-Smith, Philip; Veidenbaum, Alex; Nicolau, Alex

2017-07-01

Solar-J is a comprehensive radiative transfer model for the solar spectrum that addresses the needs of both solar heating and photochemistry in Earth system models. Solar-J is a spectral extension of Cloud-J, a standard in many chemical models that calculates photolysis rates in the 0.18-0.8 µm region. The Cloud-J core consists of an eight-stream scattering, plane-parallel radiative transfer solver with corrections for sphericity. Cloud-J uses cloud quadrature to accurately average over correlated cloud layers. It uses the scattering phase function of aerosols and clouds expanded to eighth order and thus avoids isotropic-equivalent approximations prevalent in most solar heating codes. The spectral extension from 0.8 to 12 µm enables calculation of both scattered and absorbed sunlight and thus aerosol direct radiative effects and heating rates throughout the Earth's atmosphere.The Solar-J extension adopts the correlated-k gas absorption bins, primarily water vapor, from the shortwave Rapid Radiative Transfer Model for general circulation model (GCM) applications (RRTMG-SW). Solar-J successfully matches RRTMG-SW's tropospheric heating profile in a clear-sky, aerosol-free, tropical atmosphere. We compare both codes in cloudy atmospheres with a liquid-water stratus cloud and an ice-crystal cirrus cloud. For the stratus cloud, both models use the same physical properties, and we find a systematic low bias of about 3 % in planetary albedo across all solar zenith angles caused by RRTMG-SW's two-stream scattering. Discrepancies with the cirrus cloud using any of RRTMG-SW's three different parameterizations are as large as about 20-40 % depending on the solar zenith angles and occur throughout the atmosphere.Effectively, Solar-J has combined the best components of RRTMG-SW and Cloud-J to build a high-fidelity module for the scattering and absorption of sunlight in the Earth's atmosphere, for which the three major components - wavelength integration, scattering, and

Sun and solar flares

Energy Technology Data Exchange (ETDEWEB)

McKenna-Lawlor, S. (Saint Patrick' s Coll., Maynooth (Ireland))

1982-07-01

The subject is discussed under the headings: the sun's core (thermonuclear reactions, energy transfer from core through radiation zone, convection zone, photosphere, chromosphere and corona); the photosphere (convection, granulation, sunspots, magnetic fields, solar cycle, rotation of the sun); solar variability and paleoclimatic records (correlation of low solar activity with increased /sup 14/C production in atmosphere); the chromosphere and corona (turbulence, temperature, coronal streamers, energy transfer); solar flares (cosmic rays, aurorae, spectra, velocity of flares, prominences, mechanisms of flares); the solar wind.

[Effects of reduced solar radiation on winter wheat flag leaf net photosynthetic rate].

Science.gov (United States)

Zheng, You-Fei; Ni, Yan-Li; Mai, Bo-Ru; Wu, Rong-Jun; Feng, Yan; Sun, Jian; Li, Jian; Xu, Jing-Xin

2011-06-01

Taking winter wheat Triticum aestivum L. (cv. Yangmai 13) as test material, a field experiment was conducted in Nanjing City to study the effects of simulated reduced solar radiation on the diurnal variation of winter wheat flag leaf photosynthetic rate and the main affecting factors. Five treatments were installed, i. e., 15% (T15), 20% (T20) , 40% (T40), 60% (T60), and 100% (CK) of total incident solar radiation. Reduced solar irradiance increased the chlorophyll and lutein contents significantly, but decreased the net photosynthetic rate (Pn). Under different solar irradiance, the diurnal variation of Pn had greater difference, and the daily maximum Pn was in the order of CK > T60 > T40 > T 20 > T15. In CK, the Pn exhibited a double peak diurnal curve; while in the other four treatments, the Pn showed a single peak curve, and the peak was lagged behind that of CK. Correlation analysis showed that reduced solar irradiance was the main factor affecting the diurnal variation of Pn, but the physiological parameters also played important roles in determining the diurnal variation of Pn. In treatments T60 and T40, the photosynthesis active radiation (PAR), leaf temperature (T1) , stomatal conductance (Gs) , and transpiration rate (Tr) were significantly positively correlated with Pn, suggesting their positive effects on Pn. The intercellular CO2 concentration (Ci) and stomatal limitation (Ls) had significant negative correlations with Pn in treatments T60 and T40 but significant positive correlations with Pn in treatments T20 and T15, implying that the Ci and Ls had negative (or positive) effects on Pn when the solar irradiance was higher (or lower) than 40% of incident solar irradiance.

Decrease in Hysteresis of Planetary Climate for Planets with Long Solar Days

Science.gov (United States)

Abbot, Dorian S.; Bloch-Johnson, Jonah; Checlair, Jade; Farahat, Navah X.; Graham, R. J.; Plotkin, David; Popovic, Predrag; Spaulding-Astudillo, Francisco

2018-02-01

The ice-albedo feedback on rapidly rotating terrestrial planets in the habitable zone can lead to abrupt transitions (bifurcations) between a warm and a snowball (ice-covered) state, bistability between these states, and hysteresis in planetary climate. This is important for planetary habitability because snowball events may trigger rises in the complexity of life, but could also endanger complex life that already exists. Recent work has shown that planets tidally locked in synchronous rotation states will transition smoothly into the snowball state rather than experiencing bifurcations. Here we investigate the structure of snowball bifurcations on planets that are tidally influenced, but not synchronously rotating, so that they experience long solar days. We use PlaSIM, an intermediate-complexity global climate model, with a thermodynamic mixed layer ocean and the Sun’s spectrum. We find that the amount of hysteresis (the range in stellar flux for which there is bistability in climate) is significantly reduced for solar days with lengths of tens of Earth days, and disappears for solar days of hundreds of Earth days. These results suggest that tidally influenced planets orbiting M and K stars that are not synchronously rotating could have much less hysteresis associated with the snowball bifurcations than they would if they were rapidly rotating. This implies that the amount of time it takes them to escape a snowball state via CO2 outgassing would be greatly reduced, as would the period of cycling between the warm and snowball state if they have low CO2 outgassing rates.

Effect of Rotation Rate on Microstructure and Properties of Underwater Friction Stir Welded 7A04-T6 Aluminum Alloy

Directory of Open Access Journals (Sweden)

WANG Wen

2017-10-01

Full Text Available Underwater friction stir welding (FSW on 7A04-T6 aluminum alloy plates was carried out, and the effect of rotation rate on microstructure and mechanical properties of joints was investigated. The results show that the minimum hardness of underwater FSW joints is located in the thermo-mechanically affected zone. The hardness of welded joints at the high rotation rate of 950r/min exhibits W-shaped distribution, and the average hardness value in the nugget zone is higher than that of welded joints at the low rotation rate of 475, 600, 750r/min. When the rotation rate increases from 475r/min to 750r/min with a constant welding speed of 235mm/min, the precipitated phases in the nugget zone gradually become coarse, and the ultimate tensile strength coefficient of the joint decreases from 89.71% to 82.33%; when rotation rate increases to 950r/min, the precipitated phases dissolve into aluminum matrix during welding, and age after welding. This produces the fine and homogeneous dispersed phases, which results in an increase of the strength coefficient to 89.04% and a certain enhancement of strain hardening capacity and elongation for the joints. All the tensile fracture surfaces exhibit the mixed characteristics of microporous polymerization and cleavage fracture.

Dynamic strain and rotation ground motions of the 2011 Tohoku earthquake from dense high-rate GPS observations in Taiwan

Science.gov (United States)

Huang, B. S.; Rau, R. J.; Lin, C. J.; Kuo, L. C.

2017-12-01

Seismic waves generated by the 2011 Mw 9.0 Tohoku, Japan earthquake were well recorded by continuous GPS in Taiwan. Those GPS were operated in one hertz sampling rate and densely distributed in Taiwan Island. Those continuous GPS observations and the precise point positioning technique provide an opportunity to estimate spatial derivatives from absolute ground motions of this giant teleseismic event. In this study, we process and investigate more than one and half hundred high-rate GPS displacements and its spatial derivatives, thus strain and rotations, to compare to broadband seismic and rotational sensor observations. It is shown that continuous GPS observations are highly consistent with broadband seismic observations during its surface waves across Taiwan Island. Several standard Geodesy and seismic array analysis techniques for spatial gradients have been applied to those continuous GPS time series to determine its dynamic strain and rotation time histories. Results show that those derivate GPS vertical axis ground rotations are consistent to seismic array determined rotations. However, vertical rotation-rate observations from the R1 rotational sensors have low resolutions and could not compared with GPS observations for this special event. For its dese spatial distribution of GPS stations in Taiwan Island, not only wavefield gradient time histories at individual site was obtained but also 2-D spatial ground motion fields were determined in this study also. In this study, we will report the analyzed results of those spatial gradient wavefields of the 2011 Tohoku earthquake across Taiwan Island and discuss its geological implications.

Predicting Ionization Rates from SEP and Solar Wind Proton Precipitation into the Martian Atmosphere

Science.gov (United States)

Jolitz, R.; Dong, C.; Lee, C. O.; Curry, S.; Lillis, R. J.; Brain, D.; Halekas, J. S.; Larson, D. E.; Bougher, S. W.; Jakosky, B. M.

2017-12-01

Precipitating energetic particles ionize planetary atmospheres and increase total electron content. At Mars, the solar wind and solar energetic particles (SEPs) can precipitate directly into the atmosphere because solar wind protons can charge exchange to become neutrals and pass through the magnetosheath, while SEPs are sufficiently energetic to cross the magnetosheath unchanged. In this study we will present predicted ionization rates and resulting electron densities produced by solar wind and SEP proton ionization during nominal solar activity and a CME shock front impact event on May 16 2016. We will use the Atmospheric Scattering of Protons and Energetic Neutrals (ASPEN) model to compare ionization by SEP and solar wind protons currently measured by the SWIA (Solar Wind Ion Analyzer) and SEP instruments aboard the MAVEN spacecraft. Results will help to quantify how the ionosphere responds to extreme solar events during solar minimum.

77 FR 24697 - Cooper Mountain Solar 2, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

Science.gov (United States)

2012-04-25

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER12-1566-000] Cooper Mountain Solar 2, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for... Cooper Mountain Solar 2, LLC's application for market-based rate authority, with an accompanying rate...

76 FR 44322 - Copper Mountain Solar 1, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

Science.gov (United States)

2011-07-25

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER11-4055-000] Copper Mountain Solar 1, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for... Copper Mountain Solar 1, LLC's application for market-based rate authority, with an accompanying rate...

WHAT SETS THE INITIAL ROTATION RATES OF MASSIVE STARS?

International Nuclear Information System (INIS)

Rosen, Anna L.; Krumholz, Mark R.; Ramirez-Ruiz, Enrico

2012-01-01

The physical mechanisms that set the initial rotation rates in massive stars are a crucial unknown in current star formation theory. Observations of young, massive stars provide evidence that they form in a similar fashion to their low-mass counterparts. The magnetic coupling between a star and its accretion disk may be sufficient to spin down low-mass pre-main-sequence (PMS) stars to well below breakup at the end stage of their formation when the accretion rate is low. However, we show that these magnetic torques are insufficient to spin down massive PMS stars due to their short formation times and high accretion rates. We develop a model for the angular momentum evolution of stars over a wide range in mass, considering both magnetic and gravitational torques. We find that magnetic torques are unable to spin down either low-mass or high-mass stars during the main accretion phase, and that massive stars cannot be spun down significantly by magnetic torques during the end stage of their formation either. Spin-down occurs only if massive stars' disk lifetimes are substantially longer or their magnetic fields are much stronger than current observations suggest.

A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5

Directory of Open Access Journals (Sweden)

J. Hsu

2017-07-01

Full Text Available Solar-J is a comprehensive radiative transfer model for the solar spectrum that addresses the needs of both solar heating and photochemistry in Earth system models. Solar-J is a spectral extension of Cloud-J, a standard in many chemical models that calculates photolysis rates in the 0.18–0.8 µm region. The Cloud-J core consists of an eight-stream scattering, plane-parallel radiative transfer solver with corrections for sphericity. Cloud-J uses cloud quadrature to accurately average over correlated cloud layers. It uses the scattering phase function of aerosols and clouds expanded to eighth order and thus avoids isotropic-equivalent approximations prevalent in most solar heating codes. The spectral extension from 0.8 to 12 µm enables calculation of both scattered and absorbed sunlight and thus aerosol direct radiative effects and heating rates throughout the Earth's atmosphere.The Solar-J extension adopts the correlated-k gas absorption bins, primarily water vapor, from the shortwave Rapid Radiative Transfer Model for general circulation model (GCM applications (RRTMG-SW. Solar-J successfully matches RRTMG-SW's tropospheric heating profile in a clear-sky, aerosol-free, tropical atmosphere. We compare both codes in cloudy atmospheres with a liquid-water stratus cloud and an ice-crystal cirrus cloud. For the stratus cloud, both models use the same physical properties, and we find a systematic low bias of about 3 % in planetary albedo across all solar zenith angles caused by RRTMG-SW's two-stream scattering. Discrepancies with the cirrus cloud using any of RRTMG-SW's three different parameterizations are as large as about 20–40 % depending on the solar zenith angles and occur throughout the atmosphere.Effectively, Solar-J has combined the best components of RRTMG-SW and Cloud-J to build a high-fidelity module for the scattering and absorption of sunlight in the Earth's atmosphere, for which the three major components – wavelength

The sun and solar flares

International Nuclear Information System (INIS)

McKenna-Lawlor, S.

1982-01-01

The subject is discussed under the headings: the sun's core (thermonuclear reactions, energy transfer from core through radiation zone, convection zone, photosphere, chromosphere and corona); the photosphere (convection, granulation, sunspots, magnetic fields, solar cycle, rotation of the sun); solar variability and paleoclimatic records (correlation of low solar activity with increased 14 C production in atmosphere); the chromosphere and corona (turbulence, temperature, coronal streamers, energy transfer); solar flares (cosmic rays, aurorae, spectra, velocity of flares, prominences, mechanisms of flares); the solar wind. (U.K.)

Economic analysis of solar industrial process heat systems: A methodology to determine annual required revenue and internal rate of return

Science.gov (United States)

Dickinson, W. C.; Brown, K. C.

1981-08-01

An economic evaluation of solar industrial process heat systems, is developed to determine the annual required revenue and the internal rate of return. First, a format is provided to estimate the solar system's installed cost, annual operating and maintenance expenses, and net annual solar energy delivered to the industrial process. The annual required revenue and the price of solar is calculated. The economic attractiveness of the potential solar investment can be determined by comparing the price of solar energy with the price of fossilfuel, both expressed in levelized terms. This requires calcuation of the internal rate of return on the solar investment or, in certain cases, the growth rate of return.

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.

Rates and timing of vertical-axis block rotations across the Sierra Nevada-Walker Lane transition in the Bodie Hills

Science.gov (United States)

Rood, D. H.; Herman, S.; Burbank, D.; Bogue, S.

2008-12-01

We use paleomagnetic data from Tertiary volcanic rocks to address the rates and timing of vertical-axis block rotation across the Sierra Nevada-Walker Lane transition in the Bodie Hills, California/Nevada. In zones of continental deformation, block rotations are an important mechanism for permanent stain accommodation, and thus may be crucial to testing geodetic block models and resolving geologic-geodetic slip discrepancies. In our study, data included in the paleomagetic site means are high quality AF demagnetization results (least squared fits that generally include 5-7 points with MAD values less than 1). Thermal demagnetization results match the AF directions, and both thermal demag and rockmag results indicate strong ChRM, mostly carried by single domain magnetite. The site means used to calculate the VGPs all have a95 values less than 10 (mostly 2-5) and include 6-11 sites each. Each site (and thus site mean) has a reasonably well-known structural correction. The VGP scatter values range from 12 to 16 degrees, indicating that they include appropriate secular variation. The mean declinations and 95 percent confidence limits for each VGP timeslice are statistically distinct from one another (71 ± 9, 39 ± 13, and 11 ± 11 degrees). The slope of a linear regression fit to the age versus declination data gives a rate of vertical axis block rotation of approximately 3-4 degrees/Myr. Fitting two separate lines to the age vs. declination data would indicate an increase in the rates of rotation since ~10 Ma. Two possible interpretations of the data are: (1) the rotations began during or before the Middle Miocene, or (2) rates of rotation were high initially (e.g. ~10 Ma) and decelerated until the Pliocene. These data have implications for the (1) timing and spatial extent of distributed strain accumulation related to the initiation of the San Andreas Fault-Eastern California Shear Zone-Walker Lane transform plate boundary, (2) transfer of transform plate boundary

Detection and Modeling of Non-Tidal Oceanic Effects on the Earth's Rotation Rate

Science.gov (United States)

Marcus, S. L.; Chao, Y.; Dickey, J. O.; Gegout, P.

1998-01-01

Sub-decadal changes in the Earth's rotation rate, and hence in the length-of-day (LOD), are largely controlled by variations in atmospheric angular momentum. Results from two oceanic general circulation models (OGCMs), forced by observed wind stress and heat flux for the years 1992-1994, show that ocean current and mass distribution changes also induce detectable LOD variations.

State resolved rotational excitation cross-sections and rates in H2 + H2 collisions

International Nuclear Information System (INIS)

Sultanov, Renat A.; Guster, Dennis

2006-01-01

Rotational transitions in molecular hydrogen collisions are computed. The two most recently developed potential energy surfaces for the H 2 -H 2 system are used from the following works: [A.I. Boothroyd, P.G. Martin, W.J. Keogh, M.J. Peterson, J. Chem. Phys., 116 (2002) 666; P. Diep, J.K. Johnson, J. Chem. Phys., 113 (2000) 3480; P. Diep, J.K. Johnson, J. Chem. Phys., 112 (2000) 4465]. Cross-sections for rotational transitions 00 → 20, 22, 40, 42, 44 and corresponding rate coefficients are calculated using a quantum-mechanical approach. Results are compared for a wide range of kinetic temperatures 300 K ≤ T≤ 3000 K

A SOLAR TORNADO OBSERVED BY AIA/SDO: ROTATIONAL FLOW AND EVOLUTION OF MAGNETIC HELICITY IN A PROMINENCE AND CAVITY

Energy Technology Data Exchange (ETDEWEB)

Li, Xing; Morgan, Huw; Leonard, Drew; Jeska, Lauren, E-mail: xxl@aber.ac.uk [Sefydliad Mathemateg a Ffiseg, Prifysgol Aberystwyth, Ceredigion, Cymru SY23 3BZ (United Kingdom)

2012-06-20

During 2011 September 24, as observed by the Atmospheric Imaging Assembly instrument of the Solar Dynamic Observatory and ground-based H{alpha} telescopes, a prominence and associated cavity appeared above the southwest limb. On 2011 September 25 8:00 UT, material flows upward from the prominence core along a narrow loop-like structure, accompanied by a rise ({>=}50,000 km) of the prominence core and the loop. As the loop fades by 10:00, small blobs and streaks of varying brightness rotate around the top part of the prominence and cavity, mimicking a cyclone. The most intense and coherent rotation lasts for over three hours, with emission in both hot ({approx}1 MK) and cold (hydrogen and helium) lines. We suggest that the cyclonic appearance and overall evolution of the structure can be interpreted in terms of the expansion of helical structures into the cavity, and the movement of plasma along helical structures which appears as a rotation when viewed along the helix axis. The coordinated movement of material between prominence and cavity suggests that they are structurally linked. Complexity is great due to the combined effect of these actions and the line-of-sight integration through the structure which contains tangled fields.

KIC 9451096: Magnetic Activity, Flares and Differential Rotation

Science.gov (United States)

Özdarcan, O.; Yoldaş, E.; Dal, H. A.

2018-04-01

We present a spectroscopic and photometric analysis of KIC 9451096. The combined spectroscopic and photometric modelling shows that the system is a detached eclipsing binary in a circular orbit and composed of F5V + K2V components. Subtracting the best-fitting light curve model from the whole long cadence data reveals additional low (mmag) amplitude light variations in time and occasional flares, suggesting a low, but still remarkable level of magnetic spot activity on the K2V component. Analyzing the rotational modulation of the light curve residuals enables us to estimate the differential rotation coefficient of the K2V component as k = 0.069 ± 0.008, which is 3 times weaker compared with the solar value of k = 0.19, assuming a solar type differential rotation. We find the stellar flare activity frequency for the K2V component as 0.000368411 h-1 indicating a low magnetic activity level.

Recurrent star-spot activity and differential rotation in KIC 11560447

Science.gov (United States)

Özavcı, I.; Şenavcı, H. V.; Işık, E.; Hussain, G. A. J.; O'Neal, D.; Yılmaz, M.; Selam, S. O.

2018-03-01

We present a detailed analysis of surface inhomogeneities on the K1-type subgiant component of the rapidly rotating eclipsing binary KIC 11560447, using high-precision Kepler light curves spanning nearly 4 yr, which corresponds to about 2800 orbital revolutions. We determine the system parameters precisely, using high-resolution spectra from the 2.1-m Otto Struve Telescope at the McDonald Observatory. We apply the maximum entropy method to reconstruct the relative longitudinal spot occupancy. Our numerical tests show that the procedure can recover large-scale random distributions of individually unresolved spots, and it can track the phase migration of up to three major spot clusters. By determining the drift rates of various spotted regions in orbital longitude, we suggest a way to constrain surface differential rotation and we show that the results are consistent with periodograms. The K1IV star exhibits two mildly preferred longitudes of emergence, indications of solar-like differential rotation, and a 0.5-1.3-yr recurrence period in star-spot emergence, accompanied by a secular increase in the axisymmetric component of spot occupancy.

Precision measurement of the 7Be solar neutrino rate and absence of day-night asymmetry in Borexino

International Nuclear Information System (INIS)

Davini, S.

2011-01-01

Borexino, in data taking since May 2007, is the only experiment capable to perform the measurement of low-energy solar-ν. Borexino has performed the first direct measurement of the 7 Be solar-ν rate with accuracy better than 5%. The absence of day-night asymmetry of the 7 Be solar-ν rate was measured with a total uncertainty of 1%. Borexino results alone reject the Low Δm 2 (LOW) region of solar-ν oscillation parameters at more than 8.5 σ CL. Combined with the other solar-ν data, Borexino measurements isolate the Large Mixing Angle (LMA)- Mikheyev Smirnov Wolfenstein (MSW) solution of neutrino oscillations without assuming CPT invariance in the neutrino sector.

Rotation of the Earth, solar activity and cosmic ray intensity

Energy Technology Data Exchange (ETDEWEB)

Barlyaeva, T.; Bard, E. [Aix-Marseille Univ., CNRS, IRD, Aix-en-Provence (France). CEREGE, College de France; Abarca-del-Rio, R. [Universidad de Concepcion (UDEC) (Chile). Dept. de Geofisica (DGEO)

2014-10-01

We analyse phase lags between the 11-year variations of three records: the semi-annual oscillation of the length of day (LOD), the solar activity (SA) and the cosmic ray intensity (CRI). The analysis was done for solar cycles 20-23. Observed relationships between LOD, CRI and SA are discussed separately for even and odd solar cycles. Phase lags were calculated using different methods (comparison of maximal points of cycles, maximal correlation coefficient, line of synchronization of cross-recurrence plots). We have found different phase lags between SA and CRI for even and odd solar cycles, confirming previous studies. The evolution of phase lags between SA and LOD as well as between CRI and LOD shows a positive trend with additional variations of phase lag values. For solar cycle 20, phase lags between SA and CRI, between SA and LOD, and between CRI and LOD were found to be negative. Overall, our study suggests that, if anything, the length of day could be influenced by solar irradiance rather than by cosmic rays.

Rotation of the Earth, solar activity and cosmic ray intensity

International Nuclear Information System (INIS)

Barlyaeva, T.; Bard, E.

2014-01-01

We analyse phase lags between the 11-year variations of three records: the semi-annual oscillation of the length of day (LOD), the solar activity (SA) and the cosmic ray intensity (CRI). The analysis was done for solar cycles 20-23. Observed relationships between LOD, CRI and SA are discussed separately for even and odd solar cycles. Phase lags were calculated using different methods (comparison of maximal points of cycles, maximal correlation coefficient, line of synchronization of cross-recurrence plots). We have found different phase lags between SA and CRI for even and odd solar cycles, confirming previous studies. The evolution of phase lags between SA and LOD as well as between CRI and LOD shows a positive trend with additional variations of phase lag values. For solar cycle 20, phase lags between SA and CRI, between SA and LOD, and between CRI and LOD were found to be negative. Overall, our study suggests that, if anything, the length of day could be influenced by solar irradiance rather than by cosmic rays.

Calibrationless rotating Lorentz-force flowmeters for low flow rate applications

Science.gov (United States)

Hvasta, M. G.; Dudt, D.; Fisher, A. E.; Kolemen, E.

2018-07-01

A ‘weighted magnetic bearing’ has been developed to improve the performance of rotating Lorentz-force flowmeters (RLFFs). Experiments have shown that the new bearing reduces frictional losses within a double-sided, disc-style RLFF to negligible levels. Operating such an RLFF under ‘frictionless’ conditions provides two major benefits. First, the steady-state velocity of the RLFF magnets matches the average velocity of the flowing liquid at low flow rates. This enables an RLFF to make accurate volumetric flow measurements without any calibration or prior knowledge of the fluid properties. Second, due to minimized frictional losses, an RLFF is able to measure low flow rates that cannot be detected when conventional, high-friction bearings are used. This paper provides a brief background on RLFFs, gives a detailed description of weighted magnetic bearings, and compares experimental RLFF data to measurements taken with a commercially available flowmeter.

Effect of rotation on convective mass transfer in rotating channels

International Nuclear Information System (INIS)

Pharoah, J.G.; Djilali, N.

2002-01-01

Laminar flow and mass transfer in rotating channels is investigated in the context of centrifugal membrane separation. The effect of orientation with respect to the rotational axis is examined for rectangular channels of aspect ratio 3 and the Rossby number is varied from 0.3 to 20.9. Both Ro and the channel orientation are found to have a significant effect on the flow. Mass transfer calculations corresponding to reverse osmosis desalination are carried out at various operating pressures and all rotating cases exhibit significant process enhancements at relatively low rotation rates. Finally, while it is common in the membrane literature to correlate mass transfer performance with membrane shear rates this is shown not to be valid in the cases presented herein. (author)

76 FR 32188 - Hatch Solar Energy Center 1, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

Science.gov (United States)

2011-06-03

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER11-3635-000] Hatch Solar Energy Center 1, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for... Hatch Solar Energy Center 1, LLC's application for market-based rate authority, with an accompanying...

78 FR 28836 - Arlington Valley Solar Energy II, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

Science.gov (United States)

2013-05-16

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-1430-000] Arlington Valley Solar Energy II, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request..., of Arlington Valley Solar Energy II, LLC's application for market-based rate authority, with an...

Modelling solar-like oscillators

Energy Technology Data Exchange (ETDEWEB)

Eggenberger, P; Miglio, A [Institut d' Astrophysique et de Geophysique de l' Universite de Liege, 17 Allee du 6 Aout, B-4000 Liege (Belgium); Carrier, F [Institute of Astronomy, University of Leuven, Celestijnenlaan 200 D, B-3001 Leuven (Belgium); Mathis, S [CEA/DSM/DAPNIA/Service d' Astrophysique, CEA/Saclay, AIM-Unite Mixte de Recherche CEA-CNRS-Universite Paris VII, UMR 7158, 91191 Gif-sur-Yvette Cedex (France)], E-mail: eggenberger@Qastro.ulg.ac.be

2008-10-15

The computation of models of stars for which solar-like oscillations have been observed is discussed. After a brief intoduction on the observations of solar-like oscillations, the modelling of isolated stars and of stars belonging to a binary system is presented with specific examples of recent theoretical calibrations. Finally the input physics introduced in stellar evolution codes for the computation of solar-type stars is discussed with a peculiar emphasis on the modelling of rotation for these stars.

Observational investigation of the solar oblateness

International Nuclear Information System (INIS)

Stebbins, R.T.

1975-01-01

The solar oblateness provides important information for solar physics and experimental relativity. After the solar neutrino flux, the sun's shape is the most revealing probe of the solar interior. Rapidly rotating interiors suggested to explain the solar neutrino paradox produce sizeable oblatenesses. Certain types of surface phenomena can also be investigated with precision diameter measurements. The relativistic advance of Mercury's perihelion has long been the principal experimental support for Einstein's theory of general relativity. Recent measurements of the solar oblateness have suggested that the relativistic advance is smaller than originally thought due to a contribution from a solar mass quadrupole moment. This interpretation of the perihelion advance would shift the experimental support to the scalar-tensor theory of gravitation. A debate over the interpretation of the oblateness measurements has resulted. In light of these circumstances, solar oblateness observations have been attempted. Improved experimental techniques have been devised, including a daytime astrometric telescope and an explicit definition of the sun's edge. Observations reveal a time varying excess equatorial brightness, that is, a variation in the limb darkening function between equator and pole, which would preclude accurate interpretation of previous solar oblateness measurements. This vindicates the alternate interpretations of other solar oblateness measurements. From these results, it can be concluded that the Mercury perihelion evidence firmly supports Einstein's General Theory of Relativity, the solar interiors cannot be rotating fast enough to account for the low solar neutrino flux, and a time varying excess equatorial brightness exists

Internal differential rotation of the Sun: the P-modes frequency splitting in the measurements of brightness oscillations

International Nuclear Information System (INIS)

Didkovskij, L.V.

1989-01-01

a 12-DAY SERIES OF TWO-DIMNIONAL IMAGES OF SOLAR BRIGHTNESS OSCILLATIONS EIGENFREQUENCIES in the range of 6-32 degrees. The rotational frequency splitting of separate modes as a function of inner turn-points radius of acoustic waves is found. The results of the analysis shw fast rotation of the central region of the Sun and non-monotonous trend of angular rotation velocity varitions with radius of the boundary of solar core

Preferred solar wind emitting longitudes on the sun

International Nuclear Information System (INIS)

Gosling, J.T.; Asbridge, J.R.; Bame, S.J.; Feldman, W.C.

1977-01-01

During the 11 1/2-year period from July 1964 through December 1975, high- and low-speed solar wind flows originated from preferred solar longitudes. The preferred longitude effect was most pronounced from 1970 onward but was also evident in the years preceding 1970. The most pronounced modulation in average solar wind speed with longitude (approximately 20%) was obtained when it was assumed that the synodic rotation period of the sun is 27.025 days. Some deep internal structure in the sun must ultmately be responsible for these long-lived longitudinal effects, which appear to rotate rigidly with the sun

High-rate deposition of epitaxial layers for efficient low-temperature thin film epitaxial silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Oberbeck, L.; Schmidt, J.; Wagner, T.A.; Bergmann, R.B. [Stuttgart Univ. (Germany). Inst. of Physical Electronics

2001-07-01

Low-temperature deposition of Si for thin-film solar cells has previously been hampered by low deposition rates and low material quality, usually reflected by a low open-circuit voltage of these solar cells. In contrast, ion-assisted deposition produces Si films with a minority-carrier diffusion length of 40 {mu}m, obtained at a record deposition rate of 0.8 {mu}m/min and a deposition temperature of 650{sup o}C with a prebake at 810{sup o}C. A thin-film Si solar cell with a 20-{mu}m-thick epitaxial layer achieves an open-circuit voltage of 622 mV and a conversion efficiency of 12.7% without any light trapping structures and without high-temperature solar cell process steps. (author)

The structure of rotational discontinuities

International Nuclear Information System (INIS)

Neugebauer, M.

1989-01-01

This study examines the structures of a set of rotational discontinuities detected in the solar wind by the ISEE-3 spacecraft. It is found that the complexity of the structure increases as the angle θ between the propagation vector k and the magnetic field decreases. For rotational discontinuities that propagate at a large angle to the field with an ion (left-hand) sense of rotation, the magnetic hodograms tend to be flattened, in agreement with prior numerical simulations. When θ is large, angular overshoots are often observed at one or both ends of the discontinuity. When the propagation is nearly parallel to the field (i.e., when θ is small), many different types of structure are seen, ranging from straight lines, the S-shaped curves, to complex, disorganized shapes

An MHD simulation model of time-dependent global solar corona with temporally varying solar-surface magnetic field maps

Science.gov (United States)

Hayashi, K.

2013-11-01

We present a model of a time-dependent three-dimensional magnetohydrodynamics simulation of the sub-Alfvenic solar corona and super-Alfvenic solar wind with temporally varying solar-surface boundary magnetic field data. To (i) accommodate observational data with a somewhat arbitrarily evolving solar photospheric magnetic field as the boundary value and (ii) keep the divergence-free condition, we developed a boundary model, here named Confined Differential Potential Field model, that calculates the horizontal components of the magnetic field, from changes in the vertical component, as a potential field confined in a thin shell. The projected normal characteristic method robustly simulates the solar corona and solar wind, in response to the temporal variation of the boundary Br. We conduct test MHD simulations for two periods, from Carrington Rotation number 2009 to 2010 and from Carrington Rotation 2074 to 2075 at solar maximum and minimum of Cycle 23, respectively. We obtained several coronal features that a fixed boundary condition cannot yield, such as twisted magnetic field lines at the lower corona and the transition from an open-field coronal hole to a closed-field streamer. We also obtained slight improvements of the interplanetary magnetic field, including the latitudinal component, at Earth.

Rapid vibrational and rotational energy-transfer rates in heated carbon dioxide collisions by double-resonance laser spectroscopy

International Nuclear Information System (INIS)

Thomason, M.D.

1982-07-01

Rates for resonant vibrational and rotational energy transfer from the 001 state by CO 2 + CO 2 collisions have been measured. All data were obtained by double resonance spectroscopy with CO 2 lasers in a 2.5 meter absorption cell at 700 0 K. Results for rotation transfer include pumped-level relaxation and the response of other 001 levels with ΔJ up to 18. These data are compared to four relevant collision models via a 35-level rate equation analysis. Sequence-band (002 → 101) and hot-band (011 → 110) lasting have been used to observe resonant nu 3 -transfer relaxation involving 001 + 001 reversible 002 + 000, 001 + 100 reversible 101 + 000, and 001 + 010 reversible 011 + 000. A multilevel rate analysis has been utilized to determine the rate coefficients for 001 going to the 002, the 101, and the 011 levels. Part of the hot-band data has been interpreted as due to 110 + 000 reversible 100 + 010, and the associated rate constant has been estimated. The results of the study are compared to the theory and to other experiments

46 CFR 108.437 - Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment. 108.437 Section 108.437 Shipping COAST GUARD, DEPARTMENT OF... Systems Fixed Carbon Dioxide Fire Extinguishing Systems § 108.437 Pipe sizes and discharge rates for...

The lithium-rotation connection in the 125 Myr-old Pleiades cluster

Science.gov (United States)

Bouvier, J.; Barrado, D.; Moraux, E.; Stauffer, J.; Rebull, L.; Hillenbrand, L.; Bayo, A.; Boisse, I.; Bouy, H.; DiFolco, E.; Lillo-Box, J.; Calderón, M. Morales

2018-06-01

Context. The evolution of lithium abundance over a star's lifetime is indicative of transport processes operating in the stellar interior. Aims: We revisit the relationship between lithium content and rotation rate previously reported for cool dwarfs in the Pleiades cluster. Methods: We derive new LiI 670.8 nm equivalent width measurements from high-resolution spectra obtained for low-mass Pleiades members. We combine these new measurements with previously published ones, and use the Kepler K2 rotational periods recently derived for Pleiades cool dwarfs to investigate the lithium-rotation connection in this 125 Myr-old cluster. Results: The new data confirm the correlation between lithium equivalent width and stellar spin rate for a sample of 51 early K-type members of the cluster, where fast rotating stars are systematically lithium-rich compared to slowly rotating ones. The correlation is valid for all stars over the (J-Ks) color range 0.50-0.70 mag, corresponding to a mass range from about 0.75 to 0.90 M⊙, and may extend down to lower masses. Conclusions: We argue that the dispersion in lithium equivalent widths observed for cool dwarfs in the Pleiades cluster reflects an intrinsic scatter in lithium abundances, and suggest that the physical origin of the lithium dispersion pattern is to be found in the pre-main sequence rotational history of solar-type stars. Based on observations made at Observatoire de Haute Provence (CNRS), France, at the Nordic Optical Telescope (IAC), Spain, and at the W. M. Keck Observatory, Hawaii, USA.Full Table B.1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/613/A63

Meridional circulation in rotating stars. VII. The effects of chemical inhomogeneities

International Nuclear Information System (INIS)

Tassoul, M.; Tassoul, J.

1984-01-01

In this paper we discuss the effects of a gradient of mean molecular weight μ on the rotationally driven currents that pervade the radiative zone of a single, nonmagnetic, main-sequence star. Detailed numerical calculations are made for the hydrogen-burning core of a solar-type star, assuming that departures from spherical symmetry are not too large. It is found that meridional streaming virtually dies out from the center outward as the μ-gradient grows in a leisurely fashion. This prevents a substantial mixing of matter between the inner (inhomogeneous) and outer (homogeneous) regions in the radiative zone, although the inner region may be penetrated to some degree. To first order in the ratio of the centrifugal force to gravity at the equator, this pattern of circulation is independent of the mean angular velocity. To this order, then, there is no critical rotation rate above which unimpeded mixing may take place. These quantitative results are compared with diverse statements that can be found in the phenomenological literature on rotational mixing

EVIDENCE FOR CLUSTER TO CLUSTER VARIATIONS IN LOW-MASS STELLAR ROTATIONAL EVOLUTION

International Nuclear Information System (INIS)

Coker, Carl T.; Pinsonneault, Marc; Terndrup, Donald M.

2016-01-01

The concordance model for angular momentum evolution postulates that star-forming regions and clusters are an evolutionary sequence that can be modeled with assumptions about protostar–disk coupling, angular momentum loss from magnetized winds that saturates in a mass-dependent fashion at high rotation rates, and core-envelope decoupling for solar analogs. We test this approach by combining established data with the large h Per data set from the MONITOR project and new low-mass Pleiades data. We confirm prior results that young low-mass stars can be used to test star–disk coupling and angular momentum loss independent of the treatment of internal angular momentum transport. For slow rotators, we confirm the need for star–disk interactions to evolve the ONC to older systems, using h Per (age 13 Myr) as our natural post-disk case. There is no evidence for extremely long-lived disks as an alternative to core-envelope decoupling. However, our wind models cannot evolve rapid rotators from h Per to older systems consistently, and we find that this result is robust with respect to the choice of angular momentum loss prescription. We outline two possible solutions: either there is cosmic variance in the distribution of stellar rotation rates in different clusters or there are substantially enhanced torques in low-mass rapid rotators. We favor the former explanation and discuss observational tests that could be used to distinguish them. If the distribution of initial conditions depends on environment, models that test parameters by assuming a universal underlying distribution of initial conditions will need to be re-evaluated.

EVIDENCE FOR CLUSTER TO CLUSTER VARIATIONS IN LOW-MASS STELLAR ROTATIONAL EVOLUTION

Energy Technology Data Exchange (ETDEWEB)

Coker, Carl T.; Pinsonneault, Marc; Terndrup, Donald M., E-mail: coker@astronomy.ohio-state.edu, E-mail: pinsono@astronomy.ohio-state.edu, E-mail: terndrup@astronomy.ohio-state.edu [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States)

2016-12-10

The concordance model for angular momentum evolution postulates that star-forming regions and clusters are an evolutionary sequence that can be modeled with assumptions about protostar–disk coupling, angular momentum loss from magnetized winds that saturates in a mass-dependent fashion at high rotation rates, and core-envelope decoupling for solar analogs. We test this approach by combining established data with the large h Per data set from the MONITOR project and new low-mass Pleiades data. We confirm prior results that young low-mass stars can be used to test star–disk coupling and angular momentum loss independent of the treatment of internal angular momentum transport. For slow rotators, we confirm the need for star–disk interactions to evolve the ONC to older systems, using h Per (age 13 Myr) as our natural post-disk case. There is no evidence for extremely long-lived disks as an alternative to core-envelope decoupling. However, our wind models cannot evolve rapid rotators from h Per to older systems consistently, and we find that this result is robust with respect to the choice of angular momentum loss prescription. We outline two possible solutions: either there is cosmic variance in the distribution of stellar rotation rates in different clusters or there are substantially enhanced torques in low-mass rapid rotators. We favor the former explanation and discuss observational tests that could be used to distinguish them. If the distribution of initial conditions depends on environment, models that test parameters by assuming a universal underlying distribution of initial conditions will need to be re-evaluated.

Solar Magnetized Tornadoes: Rotational Motion in a Tornado-like Prominence

Science.gov (United States)

Su, Yang; Gömöry, Peter; Veronig, Astrid; Temmer, Manuela; Wang, Tongjiang; Vanninathan, Kamalam; Gan, Weiqun; Li, YouPing

2014-04-01

Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However, no observations have successfully distinguished rotational motion of the magnetic structures in tornado-like prominences from other motions such as oscillation and counter-streaming plasma flows. Here we report evidence of rotational motions in a tornado-like prominence. The spectroscopic observations in two coronal lines were obtained from a specifically designed Hinode/EIS observing program. The data revealed the existence of both cold and million-degree-hot plasma in the prominence leg, supporting the so-called prominence-corona transition region. The opposite velocities at the two sides of the prominence and their persistent time evolution, together with the periodic motions evident in SDO/AIA dark structures, indicate a rotational motion of both cold and hot plasma with a speed of ~5 km s-1.

Simple analytical approximation for rotationally inelastic rate constants based on the energy corrected sudden scaling law

International Nuclear Information System (INIS)

Smith, N.; Pritchard, D.E.

1981-01-01

We have recently demonstrated that the energy corrected sudden (ECS) scaling law of De Pristo et al. when conbined with the power law assumption for the basis rates k/sub l/→0proportional[l(l+1)]/sup -g/ can accurately fit a wide body of rotational energy transfer data. We develop a simple and accurate approximation to this fitting law, and in addition mathematically show the connection between it and our earlier proposed energy based law which also has been successful in describing both theoretical and experimental data on rotationally inelastic collisions

On the Terminal Rotation Rates of Giant Planets

Science.gov (United States)

Batygin, Konstantin

2018-04-01

Within the general framework of the core-nucleated accretion theory of giant planet formation, the conglomeration of massive gaseous envelopes is facilitated by a transient period of rapid accumulation of nebular material. While the concurrent build-up of angular momentum is expected to leave newly formed planets spinning at near-breakup velocities, Jupiter and Saturn, as well as super-Jovian long-period extrasolar planets, are observed to rotate well below criticality. In this work, we demonstrate that the large luminosity of a young giant planet simultaneously leads to the generation of a strong planetary magnetic field, as well as thermal ionization of the circumplanetary disk. The ensuing magnetic coupling between the planetary interior and the quasi-Keplerian motion of the disk results in efficient braking of planetary rotation, with hydrodynamic circulation of gas within the Hill sphere playing the key role of expelling spin angular momentum to the circumstellar nebula. Our results place early-stage giant planet and stellar rotation within the same evolutionary framework, and motivate further exploration of magnetohydrodynamic phenomena in the context of the final stages of giant planet formation.

Recent VLA Measurements of CME-Induced Faraday Rotation

Science.gov (United States)

Kooi, Jason; Thomas, Najma; Guy, Michael; Spangler, Steven R.

2018-01-01

Observations of Faraday rotation, the change in polarization position angle of linearly polarized radiation as it propagates through a magnetized plasma, have been used for decades to determine the strength and structure of the coronal magnetic field and plasma density. Similarly, observations of Faraday rotation through a coronal mass ejection (CME) have the potential to improve our understanding of the CME’s plasma structure. We report recent results from simultaneous white-light coronagraph and radio observations made of a CME in July 2015. We made radio observations using the Karl G. Jansky Very Large Array (VLA) at 1 - 2 GHz frequencies of a set of cosmic radio sources through the solar corona at heliocentric distances that ranged between 8 - 23 solar radii. A unique aspect of these observations is that the CME occulted several of these radio sources and, therefore, our Faraday rotation measurements provide information on the plasma structure in different regions of the CME. We successfully measured CME-induced Faraday rotation along multiple lines of sight because we made special arrangements with the staff at the National Radio Astronomy Observatory to trigger VLA observations when a candidate CME appeared low in the corona in near real-time images from the Large Angle and Spectrometric Coronagraph (LASCO) C2 instrument.

EXPLOSIVE NUCLEOSYNTHESIS IN THE NEUTRINO-DRIVEN ASPHERICAL SUPERNOVA EXPLOSION OF A NON-ROTATING 15 Msun STAR WITH SOLAR METALLICITY

International Nuclear Information System (INIS)

Fujimoto, Shin-ichiro; Kotake, Kei; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

2011-01-01

We investigate explosive nucleosynthesis in a non-rotating 15 M sun star with solar metallicity that explodes by a neutrino-heating supernova (SN) mechanism aided by both standing accretion shock instability (SASI) and convection. To trigger explosions in our two-dimensional hydrodynamic simulations, we approximate the neutrino transport with a simple light-bulb scheme and systematically change the neutrino fluxes emitted from the protoneutron star. By a post-processing calculation, we evaluate abundances and masses of the SN ejecta for nuclei with a mass number ≤70, employing a large nuclear reaction network. Aspherical abundance distributions, which are observed in nearby core-collapse SN remnants, are obtained for the non-rotating spherically symmetric progenitor, due to the growth of a low-mode SASI. The abundance pattern of the SN ejecta is similar to that of the solar system for models whose masses range between (0.4-0.5) M sun of the ejecta from the inner region (≤10, 000 km) of the precollapse core. For the models, the explosion energies and the 56 Ni masses are ≅ 10 51 erg and (0.05-0.06) M sun , respectively; their estimated baryonic masses of the neutron star are comparable to the ones observed in neutron-star binaries. These findings may have little uncertainty because most of the ejecta is composed of matter that is heated via the shock wave and has relatively definite abundances. The abundance ratios for Ne, Mg, Si, and Fe observed in the Cygnus loop are reproduced well with the SN ejecta from an inner region of the 15 M sun progenitor.

Rate of loss of simazine, terbuthylazine, isoproturon, and methabenzthiazuron during soil solarization.

Science.gov (United States)

Navarro, Simón; Bermejo, Salvador; Vela, Nuria; Hernández, Joaquín

2009-07-22

This paper reports the use of solar heating by polyethylene mulching for decontamination of a silty clay-loam soil polluted with herbicides. Soil solarization, a natural and hydrothermal method commonly used for disinfesting soils, was tested during the summer season on a Hipercalcic Calcisol located in Murcia (southeast Spain) for dissipation of s-triazine (simazine and terbuthylazine) and phenylurea (isoproturon and methabenzthiazuron) herbicides using low-density (LD) and high-density (HD) polyethylene (PE) film as a cover. A well-established influence of the film was observed on the dissipation of all herbicides from the soil, although the density (0.92-0.95 g/cm(3)) of the film used (LDPE and HDPE) was not significant in terms of the rate of loss. In all cases, a quick depletion during the first 2 weeks was observed, mainly for terbuthylazine. The first-order model satisfactorily explained the dissipation process, but the Hoerl and biexponential equations were more appropriate, mainly for simazine, isoproturon, and methabenzthiazuron. In all cases, herbicides disappeared at faster rates in solarized soils (DT(50) = 4-29 days) than in nonmulched soils (DT(50) = 11-35 days), especially for terbuthylazine and isoproturon.

Theoretical study of electronic transfer current rate at dye-sensitized solar cells

Science.gov (United States)

AL-Agealy, Hadi J. M.; AlMaadhede, Taif Saad; Hassooni, Mohsin A.; Sadoon, Abbas K.; Ashweik, Ahmed M.; Mahdi, Hind Abdlmajeed; Ghadhban, Rawnaq Qays

2018-05-01

In this research, we present a theoretical study of electronic transfer kinetics rate in N719/TiO2 and N719/ZnO dye-sensitized solar cells (DSSC) systems using a simple model depending on the postulate of quantum mechanics theory. The evaluation of the electronic transition current rate in DSSC systems are function of many parameters such that; the reorientation transition energies ΛSe m D y e , the transition coupling parameter ℂT(0), potential exponential effect e-(E/C-EF ) kBT , unit cell volume VSem, and temperature T. Furthermore, the analysis of electronic transfer current rate in N719/TiO2 and N719/ZnO systems show that the rate upon dye-sensitization solar cell increases with increases of transition coupling parameter, decreasing potential that building at interface a results of different material in this devices and increasing with reorientation transition energy. On the other hand, we can find the electronic transfer behavior is dependent of the dye absorption spectrum and mainly depending on the reorientation of transition energy. The replacement of the solvents in both DSSC system caused increasing of current rates dramatically depending on polarity of solvent in subset devices. This change in current rate of electron transfer were attributed to much more available of recombination sites introduced by the solvents medium. The electronic transfer current dynamics are shown to occurs in N719/TiO2 system faster many time compare to ocuures at N719/ZnO system, this indicate that TiO2 a is a good and active material compare with ZnO to using in dye sensitized solar cell devices. In contrast, the large current rate in N719/TiO2 comparing to ZnO of N719/ZnO systems indicate that using TiO2 with N719 dye lead to increasing the efficiency of DSSC.

Stream function method for computing steady rotational transonic flows with application to solar wind-type problems

International Nuclear Information System (INIS)

Kopriva, D.A.

1982-01-01

A numerical scheme has been developed to solve the quasilinear form of the transonic stream function equation. The method is applied to compute steady two-dimensional axisymmetric solar wind-type problems. A single, perfect, non-dissipative, homentropic and polytropic gas-dynamics is assumed. The four equations governing mass and momentum conservation are reduced to a single nonlinear second order partial differential equation for the stream function. Bernoulli's equation is used to obtain a nonlinear algebraic relation for the density in terms of stream function derivatives. The vorticity includes the effects of azimuthal rotation and Bernoulli's function and is determined from quantities specified on boundaries. The approach is efficient. The number of equations and independent variables has been reduced and a rapid relaxation technique developed for the transonic full potential equation is used. Second order accurate central differences are used in elliptic regions. In hyperbolic regions a dissipation term motivated by the rotated differencing scheme of Jameson is added for stability. A successive-line-overrelaxation technique also introduced by Jameson is used to solve the equations. The nonlinear equation for the density is a double valued function of the stream function derivatives. The velocities are extrapolated from upwind points to determine the proper branch and Newton's method is used to iteratively compute the density. This allows accurate solutions with few grid points

A Solar-Pumped Fluorescence Model for Line-By-Line Emission Intensities in the B-X, A-X, and X-X Band Systems of 12C14N

Science.gov (United States)

Paganini, L.; Mumma, M. J.

2016-01-01

We present a new quantitative model for detailed solar-pumped fluorescent emission of the main isotopologue of CN. The derived fluorescence efficiencies permit estimation and interpretation of ro-vibrational infrared line intensities of CN in exospheres exposed to solar (or stellar) radiation. Our g-factors are applicable to astronomical observations of CN extending from infrared to optical wavelengths, and we compare them with previous calculations in the literature. The new model enables extraction of rotational temperature, column abundance, and production rate from astronomical observations of CN in the inner coma of comets. Our model accounts for excitation and de-excitation of rotational levels in the ground vibrational state by collisions, solar excitation to the A(sup 2)Pi(sub I) and B(sup 2)Sum(sup +) electronically excited states followed by cascade to ro-vibrational levels of X(sup 2)Sum(sup +), and direct solar infrared pumping of ro-vibrational levels in the X(sup 2)Sum(sup +) state. The model uses advanced solar spectra acquired at high spectral resolution at the relevant infrared and optical wavelengths and considers the heliocentric radial velocity of the comet (the Swings effect) when assessing the exciting solar flux for a given transition. We present model predictions for the variation of fluorescence rates with rotational temperature and heliocentric radial velocity. Furthermore, we test our fluorescence model by comparing predicted and measured line-by-line intensities for X(sup 2)Sum(sup +) (1-0) in comet C/2014 Q2 (Lovejoy), thereby identifying multiple emission lines observed at IR wavelengths.

WHY ARE RAPIDLY ROTATING M DWARFS IN THE PLEIADES SO (INFRA)RED? NEW PERIOD MEASUREMENTS CONFIRM ROTATION-DEPENDENT COLOR OFFSETS FROM THE CLUSTER SEQUENCE

Energy Technology Data Exchange (ETDEWEB)

Covey, Kevin R. [Department of Physics and Astronomy, Western Washington University, Bellingham WA 98225-9164 (United States); Agüeros, Marcel A.; Liu, Jiyu [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255 (United States); Ahmadi, Aida [Max Planck Institute for Radioastronomy, Auf dem Hügel 69, D-53121 Bonn (Germany); Laher, Russ; Surace, Jason [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Levitan, David [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Sesar, Branimir, E-mail: kevin.covey@wwu.edu [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)

2016-05-10

Stellar rotation periods ( P {sub rot}) measured in open clusters have proved to be extremely useful for studying stars’ angular momentum content and rotationally driven magnetic activity, which are both age- and mass-dependent processes. While P {sub rot} measurements have been obtained for hundreds of solar-mass members of the Pleiades, measurements exist for only a few low-mass (<0.5 M {sub ⊙}) members of this key laboratory for stellar evolution theory. To fill this gap, we report P {sub rot} for 132 low-mass Pleiades members (including nearly 100 with M ≤ 0.45 M {sub ⊙}), measured from photometric monitoring of the cluster conducted by the Palomar Transient Factory in late 2011 and early 2012. These periods extend the portrait of stellar rotation at 125 Myr to the lowest-mass stars and re-establish the Pleiades as a key benchmark for models of the transport and evolution of stellar angular momentum. Combining our new P {sub rot} with precise BVIJHK photometry reported by Stauffer et al. and Kamai et al., we investigate known anomalies in the photometric properties of K and M Pleiades members. We confirm the correlation detected by Kamai et al. between a star's P {sub rot} and position relative to the main sequence in the cluster's color–magnitude diagram. We find that rapid rotators have redder ( V − K ) colors than slower rotators at the same V , indicating that rapid and slow rotators have different binary frequencies and/or photospheric properties. We find no difference in the photometric amplitudes of rapid and slow rotators, indicating that asymmetries in the longitudinal distribution of starspots do not scale grossly with rotation rate.

Solar Plus: A Holistic Approach to Distributed Solar PV

Energy Technology Data Exchange (ETDEWEB)

O' Shaughnessy, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ardani, Kristen [National Renewable Energy Lab. (NREL), Golden, CO (United States); Cutler, Dylan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Margolis, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2017-05-25

Solar 'plus' refers to an emerging approach to distributed solar photovoltaic (PV) deployment that uses energy storage and controllable devices to optimize customer economics. The solar plus approach increases customer system value through technologies such as electric batteries, smart domestic water heaters, smart air-conditioner (AC) units, and electric vehicles We use an NREL optimization model to explore the customer-side economics of solar plus under various utility rate structures and net metering rates. We explore optimal solar plus applications in five case studies with different net metering rates and rate structures. The model deploys different configurations of PV, batteries, smart domestic water heaters, and smart AC units in response to different rate structures and customer load profiles. The results indicate that solar plus improves the customer economics of PV and may mitigate some of the negative impacts of evolving rate structures on PV economics. Solar plus may become an increasingly viable model for optimizing PV customer economics in an evolving rate environment.

Solar Plus: A Holistic Approach to Distributed Solar PV

Energy Technology Data Exchange (ETDEWEB)

OShaughnessy, Eric J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ardani, Kristen B. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cutler, Dylan S. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Margolis, Robert M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-06-08

Solar 'plus' refers to an emerging approach to distributed solar photovoltaic (PV) deployment that uses energy storage and controllable devices to optimize customer economics. The solar plus approach increases customer system value through technologies such as electric batteries, smart domestic water heaters, smart air-conditioner (AC) units, and electric vehicles We use an NREL optimization model to explore the customer-side economics of solar plus under various utility rate structures and net metering rates. We explore optimal solar plus applications in five case studies with different net metering rates and rate structures. The model deploys different configurations of PV, batteries, smart domestic water heaters, and smart AC units in response to different rate structures and customer load profiles. The results indicate that solar plus improves the customer economics of PV and may mitigate some of the negative impacts of evolving rate structures on PV economics. Solar plus may become an increasingly viable model for optimizing PV customer economics in an evolving rate environment.

Observations spotted solar type stars in Pleiades

International Nuclear Information System (INIS)

Magnitskij, A.K.

1987-01-01

The september - october 1986 observations discovered periodic light variations in three solar type stars in the Pleiades cluster: Hz 296 (0.8 M Sun ), Hz152(0.91 M Sun ) and Hz739(1.15 M Sun ). Periods and amplitudes are accordingly 2 d and 0 m .11, 4 d .12 and 0 m .07, 2 d .70 and 0 m .05. Considerable light variations of these stars in Pleiades are due to the rotation of spotted stars. Contrast spots of solar type stars likely exist when stars are young and rapidly rotate

SOLAR MAGNETIZED TORNADOES: ROTATIONAL MOTION IN A TORNADO-LIKE PROMINENCE

Energy Technology Data Exchange (ETDEWEB)

Su, Yang; Veronig, Astrid; Temmer, Manuela; Vanninathan, Kamalam [IGAM-Kanzelhöhe Observatory, Institute of Physics, University of Graz, Universitätsplatz 5, A-8010 Graz (Austria); Gömöry, Peter [Astronomical Institute of the Slovak Academy of Sciences, SK-05960 Tatranská Lomnica (Slovakia); Wang, Tongjiang [Department of Physics, the Catholic University of America, Washington, DC 20064 (United States); Gan, Weiqun; Li, YouPing, E-mail: yang.su@uni-graz.at [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2014-04-10

Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However, no observations have successfully distinguished rotational motion of the magnetic structures in tornado-like prominences from other motions such as oscillation and counter-streaming plasma flows. Here we report evidence of rotational motions in a tornado-like prominence. The spectroscopic observations in two coronal lines were obtained from a specifically designed Hinode/EIS observing program. The data revealed the existence of both cold and million-degree-hot plasma in the prominence leg, supporting the so-called prominence-corona transition region. The opposite velocities at the two sides of the prominence and their persistent time evolution, together with the periodic motions evident in SDO/AIA dark structures, indicate a rotational motion of both cold and hot plasma with a speed of ∼5 km s{sup –1}.

SOLAR MAGNETIZED TORNADOES: ROTATIONAL MOTION IN A TORNADO-LIKE PROMINENCE

International Nuclear Information System (INIS)

Su, Yang; Veronig, Astrid; Temmer, Manuela; Vanninathan, Kamalam; Gömöry, Peter; Wang, Tongjiang; Gan, Weiqun; Li, YouPing

2014-01-01

Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However, no observations have successfully distinguished rotational motion of the magnetic structures in tornado-like prominences from other motions such as oscillation and counter-streaming plasma flows. Here we report evidence of rotational motions in a tornado-like prominence. The spectroscopic observations in two coronal lines were obtained from a specifically designed Hinode/EIS observing program. The data revealed the existence of both cold and million-degree-hot plasma in the prominence leg, supporting the so-called prominence-corona transition region. The opposite velocities at the two sides of the prominence and their persistent time evolution, together with the periodic motions evident in SDO/AIA dark structures, indicate a rotational motion of both cold and hot plasma with a speed of ∼5 km s –1

THE NEW HORIZONS SOLAR WIND AROUND PLUTO (SWAP) OBSERVATIONS OF THE SOLAR WIND FROM 11–33 au

Energy Technology Data Exchange (ETDEWEB)

Elliott, H. A.; McComas, D. J.; Valek, P.; Weidner, S.; Livadiotis, G. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Nicolaou, G., E-mail: helliott@swri.edu [Swedish Institute of Space Physics, Box 812, SE-98128, Kiruna (Sweden)

2016-04-15

The Solar Wind Around Pluto (SWAP) instrument on National Aeronautics and Space Administration's New Horizons Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the solar wind in the outer heliosphere making this dataset a critical addition to the field. We created a forward model of SWAP count rates, which includes a comprehensive instrument response function based on laboratory and flight calibrations. By fitting the count rates with this model, the proton density (n), speed (V), and temperature (T) parameters are determined. Comparisons between SWAP parameters and both propagated 1 au observations and prior Voyager 2 observations indicate consistency in both the range and mean wind values. These comparisons as well as our additional findings confirm that small and midsized solar wind structures are worn down with increasing distance due to dynamic interaction of parcels of wind with different speed. For instance, the T–V relationship steepens, as the range in V is limited more than the range in T with distance. At times the T–V correlation clearly breaks down beyond 20 au, which may indicate wind currently expanding and cooling may have an elevated T reflecting prior heating and compression in the inner heliosphere. The power of wind parameters at shorter periodicities decreases with distance as the longer periodicities strengthen. The solar rotation periodicity is present in temperature beyond 20 au indicating the observed parcel temperature may reflect not only current heating or cooling, but also heating occurring closer to the Sun.

THE NEW HORIZONS SOLAR WIND AROUND PLUTO (SWAP) OBSERVATIONS OF THE SOLAR WIND FROM 11–33 au

International Nuclear Information System (INIS)

Elliott, H. A.; McComas, D. J.; Valek, P.; Weidner, S.; Livadiotis, G.; Nicolaou, G.

2016-01-01

The Solar Wind Around Pluto (SWAP) instrument on National Aeronautics and Space Administration's New Horizons Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the solar wind in the outer heliosphere making this dataset a critical addition to the field. We created a forward model of SWAP count rates, which includes a comprehensive instrument response function based on laboratory and flight calibrations. By fitting the count rates with this model, the proton density (n), speed (V), and temperature (T) parameters are determined. Comparisons between SWAP parameters and both propagated 1 au observations and prior Voyager 2 observations indicate consistency in both the range and mean wind values. These comparisons as well as our additional findings confirm that small and midsized solar wind structures are worn down with increasing distance due to dynamic interaction of parcels of wind with different speed. For instance, the T–V relationship steepens, as the range in V is limited more than the range in T with distance. At times the T–V correlation clearly breaks down beyond 20 au, which may indicate wind currently expanding and cooling may have an elevated T reflecting prior heating and compression in the inner heliosphere. The power of wind parameters at shorter periodicities decreases with distance as the longer periodicities strengthen. The solar rotation periodicity is present in temperature beyond 20 au indicating the observed parcel temperature may reflect not only current heating or cooling, but also heating occurring closer to the Sun

Measurements of coronal Faraday rotation at 4.6 R ☉

International Nuclear Information System (INIS)

Kooi, Jason E.; Fischer, Patrick D.; Buffo, Jacob J.; Spangler, Steven R.

2014-01-01

Many competing models for the coronal heating and acceleration mechanisms of the high-speed solar wind depend on the solar magnetic field and plasma structure in the corona within heliocentric distances of 5 R ☉ . We report on sensitive Very Large Array (VLA) full-polarization observations made in 2011 August, at 5.0 and 6.1 GHz (each with a bandwidth of 128 MHz) of the radio galaxy 3C 228 through the solar corona at heliocentric distances of 4.6-5.0 R ☉ . Observations at 5.0 GHz permit measurements deeper in the corona than previous VLA observations at 1.4 and 1.7 GHz. These Faraday rotation observations provide unique information on the magnetic field in this region of the corona. The measured Faraday rotation on this day was lower than our a priori expectations, but we have successfully modeled the measurement in terms of observed properties of the corona on the day of observation. Our data on 3C 228 provide two lines of sight (separated by 46'', 33,000 km in the corona). We detected three periods during which there appeared to be a difference in the Faraday rotation measure between these two closely spaced lines of sight. These measurements (termed differential Faraday rotation) yield an estimate of 2.6-4.1 GA for coronal currents. Our data also allow us to impose upper limits on rotation measure fluctuations caused by coronal waves; the observed upper limits were 3.3 and 6.4 rad m –2 along the two lines of sight. The implications of these results for Joule heating and wave heating are briefly discussed.

Solar Stereoscopy and Tomography

Directory of Open Access Journals (Sweden)

Markus J. Aschwanden

2011-10-01

Full Text Available We review stereoscopic and tomographic methods used in the solar corona, including ground-based and space-based measurements, using solar rotation or multiple spacecraft vantage points, in particular from the STEREO mission during 2007--2010. Stereoscopic and tomographic observations in the solar corona include large-scale structures, streamers, active regions, coronal loops, loop oscillations, acoustic waves in loops, erupting filaments and prominences, bright points, jets, plumes, flares, CME source regions, and CME-triggered global coronal waves. Applications in the solar interior (helioseismic tomography and reconstruction and tracking of CMEs from the outer corona and into the heliosphere (interplanetary CMEs are not included.

Ring current energy injection rate and solar wind-magnetosphere energy coupling

International Nuclear Information System (INIS)

Lee, L.C.; Kan, J.R.; Akasofu, S.-I.

1982-01-01

The purpose of this paper is to (i) formulate the ring current injection rate Usub(R) in terms of phisub(CT) (cross-tail potential drop) by assuming that the ring current formation is a direct consequence of an enhanced convection, (ii) examine the relationship between the injection rate Usub(R) and the power transferred from the solar wind to the magnetosphere and (iii) demonstrate that an enhanced convection indeed leads to the formation of the ring current. (author)

Spinning rate decay of levitated high-Tc superconductors in rotational magnetic field

Energy Technology Data Exchange (ETDEWEB)

Terentiev, A.N.; Kutukova, E.O.; Kuznetsov, A.A. (Inst. of Chemical Physics, Academy of Sciences, Moscow (Russia)); Mozhaev, A.P. (Moscow State Univ., Dept. of Chemistry (Russia))

1992-04-01

The rotation damping of a levitated superconductor was examined in the static field of a ring-shaped magnet and in the rotating field of coils. It was demonstrated that the pinning force mainly contributed to magnetic friction while the influence of a viscous component was negligible. The rotating magnetic field created a torque, reducing the angular deceleration under relaxation. Dependence of the rotational field-induced torque on the field-intensity was step-like. A relationship between the step-like behavior of rotational field-induced torque and pinning center distribution is discussed. The origins of friction torque and rotational field-produced torque are discussed. (orig.).

Modes of uncontrolled rotational motion of the Progress M-29M spacecraft

Science.gov (United States)

Belyaev, M. Yu.; Matveeva, T. V.; Monakhov, M. I.; Rulev, D. N.; Sazonov, V. V.

2018-01-01

We have reconstructed the uncontrolled rotational motion of the Progress M-29M transport cargo spacecraft in the single-axis solar orientation mode (the so-called sunward spin) and in the mode of the gravitational orientation of a rotating satellite. The modes were implemented on April 3-7, 2016 as a part of preparation for experiments with the DAKON convection sensor onboard the Progress spacecraft. The reconstruction was performed by integral statistical techniques using the measurements of the spacecraft's angular velocity and electric current from its solar arrays. The measurement data obtained in a certain time interval have been jointly processed using the least-squares method by integrating the equations of the spacecraft's motion relative to the center of mass. As a result of processing, the initial conditions of motion and parameters of the mathematical model have been estimated. The motion in the sunward spin mode is the rotation of the spacecraft with an angular velocity of 2.2 deg/s about the normal to the plane of solar arrays; the normal is oriented toward the Sun or forms a small angle with this direction. The duration of the mode is several orbit passes. The reconstruction has been performed over time intervals of up to 1 h. As a result, the actual rotational motion of the spacecraft relative to the Earth-Sun direction was obtained. In the gravitational orientation mode, the spacecraft was rotated about its longitudinal axis with an angular velocity of 0.1-0.2 deg/s; the longitudinal axis executed small oscillated relative to the local vertical. The reconstruction of motion relative to the orbital coordinate system was performed in time intervals of up to 7 h using only the angularvelocity measurements. The measurements of the electric current from solar arrays were used for verification.

Solar Probe Plus

Science.gov (United States)

Szabo, Adam

2011-01-01

The NASA Solar Probe Plus mission is planned to be launched in 2018 to study the upper solar corona with both.in-situ and remote sensing instrumentation. The mission will utilize 6 Venus gravity assist maneuver to gradually lower its perihelion to 9.5 Rs below the expected Alfven pOint to study the sub-alfvenic solar wind that is still at least partially co-rotates with the Sun. The detailed science objectives of this mission will be discussed. SPP will have a strong synergy with The ESA/NASA Solar orbiter mission to be launched a year ahead. Both missions will focus on the inner heliosphere and will have complimentary instrumentations. Strategies to exploit this synergy will be also presented.

Atmospheric solar heating rate in the water vapor bands

Science.gov (United States)

Chou, Ming-Dah

1986-01-01

The total absorption of solar radiation by water vapor in clear atmospheres is parameterized as a simple function of the scaled water vapor amount. For applications to cloudy and hazy atmospheres, the flux-weighted k-distribution functions are computed for individual absorption bands and for the total near-infrared region. The parameterization is based upon monochromatic calculations and follows essentially the scaling approximation of Chou and Arking, but the effect of temperature variation with height is taken into account in order to enhance the accuracy. Furthermore, the spectral range is extended to cover the two weak bands centered at 0.72 and 0.82 micron. Comparisons with monochromatic calculations show that the atmospheric heating rate and the surface radiation can be accurately computed from the parameterization. Comparisons are also made with other parameterizations. It is found that the absorption of solar radiation can be computed reasonably well using the Goody band model and the Curtis-Godson approximation.

Deciphering Solar Magnetic Activity: Spotting Solar Cycle 25

Energy Technology Data Exchange (ETDEWEB)

McIntosh, Scott W. [High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO (United States); Leamon, Robert J., E-mail: mscott@ucar.edu [Department of Astronomy, University of Maryland, College Park, MD (United States)

2017-06-26

We present observational signatures of solar cycle 25 onset. Those signatures are visibly following a migratory path from high to low latitudes. They had starting points that are asymmetrically offset in each hemisphere at times that are 21–22 years after the corresponding, same polarity, activity bands of solar cycle 23 started their migration. Those bands define the so-called “extended solar cycle.” The four magnetic bands currently present in the system are approaching a mutually cancelling configuration, and solar minimum conditions are imminent. Further, using a tuned analysis of the daily band latitude-time diagnostics, we are able to utilize the longitudinal wave number (m = 1) variation in the data to more clearly reveal the presence of the solar cycle 25 bands. This clarification illustrates that prevalently active longitudes (different in each hemisphere) exist at mid-latitudes presently, lasting many solar rotations, that can be used for detailed study over the next several years with instruments like the Spectrograph on IRIS, the Spectropolarimeter on Hinode, and, when they come online, similar instruments on the Daniel K. Inouye Solar Telescope (DKIST) as we watch those bands evolve following the cancellation of the solar cycle 24 activity bands at the equator late in 2019.

Open magnetic fields and the solar cycle. Pt. 1

International Nuclear Information System (INIS)

Levine, R.H.

1982-01-01

Models of open magnetic structures on the Sun are presented for periods near solar minimum (CR 1626-1634) and near solar maximum (CR 1668-1678). Together with previous models of open magnetic structures during the declining phase (CR 1601-1611) these calculations provide clues to the relations between open structures, coronal holes, and active regions at different times of the solar cycle. Near solar minimum the close relation between active regions and open structures does not exist. It is suggested that near solar minimum the systematic emergence of new flux with the proper polarity imbalance to maintain open magnetic structures may occur primarily at very small spatial scales. Near solar maximum the role of active regions in maintaining open structures and coronal holes is strong, with large active regions emerging in the proper location and orientation to maintain open structures longer than typical active region lifetimes. Although the use of He I 10830 A spectroheliograms as a coronal hole indicator is shown to be subject to significant ambiguity, the agreement between calculated open structures and coronal holes determined from He I 10830 A spectroheliograms is very good. The rotation properties of calculated open structures near solar maximum strongly suggest two classes of features: one that rotates differentially similar to sunspots and active regions and a separate class that rotates more rigidly, as was the case for single large coronal holes during Skylab. (orig.)

Immobilization in External Rotation Versus Internal Rotation After Primary Anterior Shoulder Dislocation: A Meta-analysis of Randomized Controlled Trials.

Science.gov (United States)

Whelan, Daniel B; Kletke, Stephanie N; Schemitsch, Geoffrey; Chahal, Jaskarndip

2016-02-01

The recurrence rate after primary anterior shoulder dislocation is high, especially in young, active individuals. Recent studies have suggested external rotation immobilization as a method to reduce the rate of recurrent shoulder dislocation in comparison to traditional sling immobilization. To assess and summarize evidence from randomized controlled trials on the effect of internal rotation versus external rotation immobilization on the rate of recurrence after primary anterior shoulder dislocation. Meta-analysis. PubMed, MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, and abstracts from recent proceedings were searched for eligible studies. Two reviewers selected studies for inclusion, assessed methodological quality, and extracted data. Six randomized controlled trials (632 patients) were included in this review. Demographic and prognostic variables measured at baseline were similar in the pooled groups. The average age was 30.1 years in the pooled external rotation group and 30.3 years in the pooled internal rotation group. Two studies found that external rotation immobilization reduced the rate of recurrence after initial anterior shoulder dislocation compared with conventional internal rotation immobilization, whereas 4 studies failed to find a significant difference between the 2 groups. This meta-analysis suggested no overall significant difference in the rate of recurrence among patients treated with internal rotation versus external rotation immobilization (risk ratio, 0.69; 95% CI, 0.42-1.14; P = .15). There was no significant difference in the rate of compliance between internal and external rotation immobilization (P = .43). The Western Ontario Shoulder Instability Index scores were pooled across 3 studies, and there was no significant difference between the 2 groups (P = .54). Immobilization in external rotation is not significantly more effective in reducing the recurrence rate after primary anterior shoulder dislocation than

Flow past a rotating cylinder

Science.gov (United States)

Mittal, Sanjay; Kumar, Bhaskar

2003-02-01

Flow past a spinning circular cylinder placed in a uniform stream is investigated via two-dimensional computations. A stabilized finite element method is utilized to solve the incompressible Navier Stokes equations in the primitive variables formulation. The Reynolds number based on the cylinder diameter and free-stream speed of the flow is 200. The non-dimensional rotation rate, [alpha] (ratio of the surface speed and freestream speed), is varied between 0 and 5. The time integration of the flow equations is carried out for very large dimensionless time. Vortex shedding is observed for [alpha] cylinder. The results from the stability analysis for the rotating cylinder are in very good agreement with those from direct numerical simulations. For large rotation rates, very large lift coefficients can be obtained via the Magnus effect. However, the power requirement for rotating the cylinder increases rapidly with rotation rate.

THE ROTATION RATES OF MASSIVE STARS: THE ROLE OF BINARY INTERACTION THROUGH TIDES, MASS TRANSFER, AND MERGERS

Energy Technology Data Exchange (ETDEWEB)

De Mink, S. E. [Space Telescope Science Institute, Baltimore, MD (United States); Langer, N.; Izzard, R. G. [Argelander-Institut fuer Astronomie der Universitaet Bonn, D-53121 Bonn (Germany); Sana, H.; De Koter, A. [Astronomical Institute Anton Pannekoek, University of Amsterdam, 1098 XH Amsterdam (Netherlands)

2013-02-20

Rotation is thought to be a major factor in the evolution of massive stars-especially at low metallicity-with consequences for their chemical yields, ionizing flux, and final fate. Deriving the birth spin distribution is of high priority given its importance as a constraint on theories of massive star formation and as input for models of stellar populations in the local universe and at high redshift. Recently, it has become clear that the majority of massive stars interact with a binary companion before they die. We investigate how this affects the distribution of rotation rates, through stellar winds, expansion, tides, mass transfer, and mergers. For this purpose, we simulate a massive binary-star population typical for our Galaxy assuming continuous star formation. We find that, because of binary interaction, 20{sup +5} {sub -10}% of all massive main-sequence stars have projected rotational velocities in excess of 200 km s{sup -1}. We evaluate the effect of uncertain input distributions and physical processes and conclude that the main uncertainties are the mass transfer efficiency and the possible effect of magnetic braking, especially if magnetic fields are generated or amplified during mass accretion and stellar mergers. The fraction of rapid rotators we derive is similar to that observed. If indeed mass transfer and mergers are the main cause for rapid rotation in massive stars, little room remains for rapidly rotating stars that are born single. This implies that spin-down during star formation is even more efficient than previously thought. In addition, this raises questions about the interpretation of the surface abundances of rapidly rotating stars as evidence for rotational mixing. Furthermore, our results allow for the possibility that all early-type Be stars result from binary interactions and suggest that evidence for rotation in explosions, such as long gamma-ray bursts, points to a binary origin.

Precision Measurement of the Be7 Solar Neutrino Interaction Rate in Borexino

Science.gov (United States)

Bellini, G.; Benziger, J.; Bick, D.; Bonetti, S.; Bonfini, G.; Buizza Avanzini, M.; Caccianiga, B.; Cadonati, L.; Calaprice, F.; Carraro, C.; Cavalcante, P.; Chavarria, A.; D'Angelo, D.; Davini, S.; Derbin, A.; Etenko, A.; Fomenko, K.; Franco, D.; Galbiati, C.; Gazzana, S.; Ghiano, C.; Giammarchi, M.; Goeger-Neff, M.; Goretti, A.; Grandi, L.; Guardincerri, E.; Hardy, S.; Ianni, Aldo; Ianni, Andrea; Kobychev, V.; Korablev, D.; Korga, G.; Koshio, Y.; Kryn, D.; Laubenstein, M.; Lewke, T.; Litvinovich, E.; Loer, B.; Lombardi, F.; Lombardi, P.; Ludhova, L.; Machulin, I.; Manecki, S.; Maneschg, W.; Manuzio, G.; Meindl, Q.; Meroni, E.; Miramonti, L.; Misiaszek, M.; Montanari, D.; Mosteiro, P.; Muratova, V.; Oberauer, L.; Obolensky, M.; Ortica, F.; Pallavicini, M.; Papp, L.; Peña-Garay, C.; Perasso, L.; Perasso, S.; Pocar, A.; Raghavan, R. S.; Ranucci, G.; Razeto, A.; Re, A.; Romani, A.; Sabelnikov, A.; Saldanha, R.; Salvo, C.; Schönert, S.; Simgen, H.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Sukhotin, S.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Vignaud, D.; Vogelaar, R. B.; von Feilitzsch, F.; Winter, J.; Wojcik, M.; Wright, A.; Wurm, M.; Xu, J.; Zaimidoroga, O.; Zavatarelli, S.; Zuzel, G.

2011-09-01

The rate of neutrino-electron elastic scattering interactions from 862 keV Be7 solar neutrinos in Borexino is determined to be 46.0±1.5(stat)-1.6+1.5(syst)counts/(day·100ton). This corresponds to a νe-equivalent Be7 solar neutrino flux of (3.10±0.15)×109cm-2s-1 and, under the assumption of νe transition to other active neutrino flavours, yields an electron neutrino survival probability of 0.51±0.07 at 862 keV. The no flavor change hypothesis is ruled out at 5.0σ. A global solar neutrino analysis with free fluxes determines Φpp=6.06-0.06+0.02×1010cm-2s-1 and ΦCNOMikheyev-Smirnov-Wolfenstein large mixing angle neutrino oscillation model is experimentally tested at low energy.

Mass-loss Rates from Coronal Mass Ejections: A Predictive Theoretical Model for Solar-type Stars

Energy Technology Data Exchange (ETDEWEB)

Cranmer, Steven R. [Department of Astrophysical and Planetary Sciences, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309 (United States)

2017-05-10

Coronal mass ejections (CMEs) are eruptive events that cause a solar-type star to shed mass and magnetic flux. CMEs tend to occur together with flares, radio storms, and bursts of energetic particles. On the Sun, CME-related mass loss is roughly an order of magnitude less intense than that of the background solar wind. However, on other types of stars, CMEs have been proposed to carry away much more mass and energy than the time-steady wind. Earlier papers have used observed correlations between solar CMEs and flare energies, in combination with stellar flare observations, to estimate stellar CME rates. This paper sidesteps flares and attempts to calibrate a more fundamental correlation between surface-averaged magnetic fluxes and CME properties. For the Sun, there exists a power-law relationship between the magnetic filling factor and the CME kinetic energy flux, and it is generalized for use on other stars. An example prediction of the time evolution of wind/CME mass-loss rates for a solar-mass star is given. A key result is that for ages younger than about 1 Gyr (i.e., activity levels only slightly higher than the present-day Sun), the CME mass loss exceeds that of the time-steady wind. At younger ages, CMEs carry 10–100 times more mass than the wind, and such high rates may be powerful enough to dispel circumstellar disks and affect the habitability of nearby planets. The cumulative CME mass lost by the young Sun may have been as much as 1% of a solar mass.

Solar and stellar flares and their impact on planets

Science.gov (United States)

Shibata, Kazunari

Recent observations of the Sun revealed that the solar atmosphere is full of flares and flare-like phenomena, which affect terrestrial environment and our civilization. It has been established that flares are caused by the release of magnetic energy through magnetic reconnection. Many stars show flares similar to solar flares, and such stellar flares especially in stars with fast rotation are much more energetic than solar flares. These are called superflares. The total energy of a solar flare is 1029 - 1032 erg, while that of a superflare is 1033 - 1038 erg. Recently, it was found that superflares (with 1034 - 1035 erg) occur on Sun-like stars with slow rotation with frequency once in 800 - 5000 years. This suggests the possibility of superflares on the Sun. We review recent development of solar and stellar flare research, and briefly discuss possible impacts of superflares on the Earth and exoplanets.

Process parameter impact on properties of sputtered large-area Mo bilayers for CIGS thin film solar cell applications

Energy Technology Data Exchange (ETDEWEB)

Badgujar, Amol C.; Dhage, Sanjay R., E-mail: dhage@arci.res.in; Joshi, Shrikant V.

2015-08-31

Copper indium gallium selenide (CIGS) has emerged as a promising candidate for thin film solar cells, with efficiencies approaching those of silicon-based solar cells. To achieve optimum performance in CIGS solar cells, uniform, conductive, stress-free, well-adherent, reflective, crystalline molybdenum (Mo) thin films with preferred orientation (110) are desirable as a back contact on large area glass substrates. The present study focuses on cylindrical rotating DC magnetron sputtered bilayer Mo thin films on 300 mm × 300 mm soda lime glass (SLG) substrates. Key sputtering variables, namely power and Ar gas flow rates, were optimized to achieve best structural, electrical and optical properties. The Mo films were comprehensively characterized and found to possess high degree of thickness uniformity over large area. Best crystallinity, reflectance and sheet resistance was obtained at high sputtering powers and low argon gas flow rates, while mechanical properties like adhesion and residual stress were found to be best at low sputtering power and high argon gas flow rate, thereby indicating a need to arrive at a suitable trade-off during processing. - Highlights: • Sputtering of bilayer molybdenum thin films on soda lime glass • Large area deposition using rotating cylindrical direct current magnetron • Trade of sputter process parameters power and pressure • High uniformity of thickness and best electrical properties obtained • Suitable mechanical and optical properties of molybdenum are achieved for CIGS application.

78 FR 29130 - Solar Star California XIX, LLC; Supplemental Notice that Initial Market-Based Rate Filing...

Science.gov (United States)

2013-05-17

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-1441-000] Solar Star California XIX, LLC; Supplemental Notice that Initial Market-Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding, of Solar Star...

Invariant Solar Sail Formations in Elliptical Sun-Synchronous Orbits

Science.gov (United States)

Parsay, Khashayar

Current and past missions that study the Earth's geomagnetic tail require multiple spacecraft to fly in formation about a highly eccentric Keplerian reference orbit that has its apogee inside a predefined science region of interest. Because the geomagnetic tail is directed along the Sun-Earth line and therefore rotates annually, inertially fixed Keplerian orbits are only aligned with the geomagnetic tail once per year. This limitation reduces the duration of the science phase to less than a few months annually. Solar sails are capable of creating non-Keplerian, Sun-synchronous orbits that rotate with the geomagnetic tail. A solar sail flying in a Sun-synchronous orbit will have a continuous presence in the geomagnetic tail throughout the entire year, which significantly improves the in situ observations of the magnetosphere. To achieve a Sun-synchronous orbit, a solar sail is required to maintain a Sun-pointing attitude, which leads to the artificial precession of the orbit apse line in a Sun-synchronous manner, leaving the orbit apogee inside the science region of interest throughout entire the year. To study the spatial and temporal variations of plasma in the highly dynamic environment of the magnetosphere, multiple spacecraft must fly in a formation. The objective for this dissertation is to investigate the feasibility of solar sail formation flying in the Earth-centered, Sun-synchronous orbit regime. The focus of this effort is to enable formation flying for a group of solar sails that maintain a nominally fixed Sun-pointing attitude during formation flight, solely for the purpose of precessing their orbit apse lines Sun-synchronously. A fixed-attitude solar sail formation is motivated by the difficulties in the simultaneous control of orbit and attitude in flying solar sails. First, the secular rates of the orbital elements resulting from the effects of solar radiation pressure (SRP) are determined using averaging theory for a Sun-pointing attitude sail

Solar 'hot spots' are still hot

Science.gov (United States)

Bai, Taeil

1990-01-01

Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22.

The solar ionisation rate deduced from Ulysses measurements and its implications to interplanetary Lyman alpha-intensity

Science.gov (United States)

Summanen, T.; Kyroelae, E.

1995-01-01

We have developed a computer code which can be used to study 3-dimensional and time-dependent effects of the solar cycle on the interplanetary (IP) hydrogen distribution. The code is based on the inverted Monte Carlo simulation. In this work we have modelled the temporal behaviour of the solar ionisation rate. We have assumed that during the most of the time of the solar cycle there is an anisotopic latitudinal structure but right at the solar maximum the anisotropy disappears. The effects of this behaviour will be discussed both in regard to the IP hydrogen distribution and IP Lyman a a-intensity.

Baroclinic Instability in the Solar Tachocline for Continuous Vertical Profiles of Rotation, Effective Gravity, and Toroidal Field

Energy Technology Data Exchange (ETDEWEB)

Gilman, Peter A., E-mail: gilman@ucar.edu [High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Green, Boulder, CO 80307-3000 (United States)

2017-06-20

We present results from an MHD model for baroclinic instability in the solar tachocline that includes rotation, effective gravity, and toroidal field that vary continuously with height. We solve the perturbation equations using a shooting method. Without toroidal fields but with an effective gravity declining linearly from a maximum at the bottom to much smaller values at the top, we find instability at all latitudes except at the poles, at the equator, and where the vertical rotation gradient vanishes (32.°3) for longitude wavenumbers m from 1 to >10. High latitudes are much more unstable than low latitudes, but both have e -folding times that are much shorter than a sunspot cycle. The higher the m and the steeper the decline in effective gravity, the closer the unstable mode peak to the top boundary, where the energy available to drive instability is greatest. The effect of the toroidal field is always stabilizing, shrinking the latitude ranges of instability as the toroidal field is increased. The larger the toroidal field, the smaller the longitudinal wavenumber of the most unstable disturbance. All latitudes become stable for a toroidal field exceeding about 4 kG. The results imply that baroclinic instability should occur in the tachocline at latitudes where the toroidal field is weak or is changing sign, but not where the field is strong.

Measurement of the solar neutrino capture rate with gallium metal. III. Results for the 2002-2007 data-taking period

International Nuclear Information System (INIS)

Abdurashitov, J. N.; Gavrin, V. N.; Gorbachev, V. V.; Gurkina, P. P.; Ibragimova, T. V.; Kalikhov, A. V.; Khairnasov, N. G.; Knodel, T. V.; Mirmov, I. N.; Shikhin, A. A.; Veretenkin, E. P.; Yants, V. E.; Zatsepin, G. T.; Bowles, T. J.; Elliott, S. R.; Teasdale, W. A.; Nico, J. S.; Cleveland, B. T.; Wilkerson, J. F.

2009-01-01

The Russian-American experiment SAGE began to measure the solar neutrino capture rate with a target of gallium metal in December 1989. Measurements have continued with only a few brief interruptions since that time. In this article we present the experimental improvements in SAGE since its last published data summary in December 2001. Assuming the solar neutrino production rate was constant during the period of data collection, combined analysis of 168 extractions through December 2007 gives a capture rate of solar neutrinos with energy more than 233 keV of 65.4 -3.0 +3.1 (stat) -2.8 +2.6 (syst) SNU. The weighted average of the results of all three Ga solar neutrino experiments, SAGE, Gallex, and GNO, is now 66.1±3.1 SNU, where statistical and systematic uncertainties have been combined in quadrature. During the recent period of data collection a new test of SAGE was made with a reactor-produced 37 Ar neutrino source. The ratio of observed to calculated rates in this experiment, combined with the measured rates in the three prior 51 Cr neutrino-source experiments with Ga, is 0.87±0.05. A probable explanation for this low result is that the cross section for neutrino capture by the two lowest-lying excited states in 71 Ge has been overestimated. If we assume these cross sections are zero, then the standard solar model including neutrino oscillations predicts a total capture rate in Ga in the range of 63 SNU to 66 SNU with an uncertainty of about 4%, in good agreement with experiment. We derive the current value of the neutrino flux produced in the Sun by the proton-proton fusion reaction to be φ pp · =(6.0±0.8)x10 10 /(cm 2 s), which agrees well with the pp flux predicted by the standard solar model. Finally, we make several tests and show that the data are consistent with the assumption that the solar neutrino production rate is constant in time.

Critical fields and growth rates of the Tayler instability as probed by a columnar gallium experiment

OpenAIRE

Ruediger, Guenther; Gellert, Marcus; Schultz, Manfred; Strassmeier, Klaus G.; Stefani, Frank; Gundrum, Thomas; Seilmayer, Martin; Gerbeth, Gunter

2012-01-01

Many astrophysical phenomena (such as the slow rotation of neutron stars or the rigid rotation of the solar core) can be explained by the action of the Tayler instability of toroidal magnetic fields in the radiative zones of stars. In order to place the theory of this instability on a safe fundament it has been realized in a laboratory experiment measuring the critical field strength, the growth rates as well as the shape of the supercritical modes. A strong electrical current flows through a...

Healing rates for challenging rotator cuff tears utilizing an acellular human dermal reinforcement graft

Science.gov (United States)

Agrawal, Vivek

2012-01-01

Purpose: This study presents a retrospective case series of the clinical and structural outcomes (1.5 T MRI) of arthroscopic rotator cuff repair with acellular human dermal graft reinforcement performed by a single surgeon in patients with large, massive, and previously repaired rotator cuff tears. Materials and Methods: Fourteen patients with mean anterior to posterior tear size 3.87 ± 0.99 cm (median 4 cm, range 2.5–6 cm) were enrolled in the study and were evaluated for structural integrity using a high-field (1.5 T) MRI at an average of 16.8 months after surgery. The Constant-Murley scores, the Flexilevel Scale of Shoulder Function (Flex SF), scapular plane abduction, and strength were analyzed. Results: MRI results showed that the rotator cuff repair was intact in 85.7% (12/14) of the patients studied. Two patients had a Sugaya Type IV recurrent tear (2 of 14; 14.3%), which were both less than 1 cm. The Constant score increased from a preoperative mean of 49.72 (range 13–74) to a postoperative mean of 81.07 (range 45–92) (P value = 0.009). Flexilevel Scale of Shoulder Function (Flex SF) Score normalized to a 100-point scale improved from a preoperative mean of 53.69 to a postoperative mean of 79.71 (P value = 0.003). The Pain Score improved from a preoperative mean of 7.73 to a postoperative mean of 13.57 (P value = 0.008). Scapular plane abduction improved from a preoperative mean of 113.64° to a postoperative mean of 166.43° (P value = 0.010). The strength subset score improved from a preoperative mean of 1.73 kg to a postoperative mean of 7.52 kg (P value = 0.006). Conclusions: This study presents a safe and effective technique that may help improve the healing rates of large, massive, and revision rotator cuff tears with the use of an acellular human dermal allograft. This technique demonstrated favorable structural healing rates and statistically improved functional outcomes in the near term. Level of Evidence: 4. Retrospective case series. PMID

Probable Rotation States of Rocket Bodies in Low Earth Orbit

Science.gov (United States)

Ojakangas, Gregory W.; Anz-Meador, P.; Cowardin, H.

2012-01-01

In order for Active Debris Removal to be accomplished, it is critically important to understand the probable rotation states of orbiting, spent rocket bodies. As compared to the question of characterizing small unresolved debris, in this problem there are several advantages: (1) objects are of known size, mass, shape and color, (2) they have typically been in orbit for a known period of time, (3) they are large enough that resolved images may be obtainable for verification of predicted orientation, and (4) the dynamical problem is simplified to first order by largely cylindrical symmetry. It is also nearly certain for realistic rocket bodies that internal friction is appreciable in the case where residual liquid or, to a lesser degree, unconsolidated solid fuels exist. Equations of motion have been developed for this problem in which internal friction as well as torques due to solar radiation, magnetic induction, and gravitational gradient are included. In the case of pure cylindrical symmetry, the results are compared to analytical predictions patterned after the standard approach for analysis of symmetrical tops. This is possible because solar radiation and gravitational torques may be treated as conservative. Agreement between results of both methods ensures their mutual validity. For monotone symmetric cylinders, solar radiation torque vanishes if the center of mass resides at the geometric center of the object. Results indicate that in the absence of solar radiation effects, rotation states tend toward an equilibrium configuration in which rotation is about the axis of maximum inertia, with the axis of minimum inertia directed toward the center of the earth. Solar radiation torque introduces a modification to this orientation. The equilibrium state is asymptotically approached within a characteristic timescale given by a simple ratio of relevant characterizing parameters for the body in question. Light curves are simulated for the expected asymptotic final

Solar wind ion trends and signatures: STEREO PLASTIC observations approaching solar minimum

Directory of Open Access Journals (Sweden)

A. B. Galvin

2009-10-01

Full Text Available STEREO has now completed the first two years of its mission, moving from close proximity to Earth in 2006/2007 to more than 50 degrees longitudinal separation from Earth in 2009. During this time, several large-scale structures have been observed in situ. Given the prevailing solar minimum conditions, these structures have been predominantly coronal hole-associated solar wind, slow solar wind, their interfaces, and the occasional transient event. In this paper, we extend earlier solar wind composition studies into the current solar minimum using high-resolution (1-h sampling times for the charge state analysis. We examine 2-year trends for iron charge states and solar wind proton speeds, and present a case study of Carrington Rotation 2064 (December 2007 which includes minor ion (He, Fe, O kinetic and Fe composition parameters in comparison with proton and magnetic field signatures at large-scale structures observed during this interval.

Precision measurement of the (7)Be solar neutrino interaction rate in Borexino.

Science.gov (United States)

Bellini, G; Benziger, J; Bick, D; Bonetti, S; Bonfini, G; Buizza Avanzini, M; Caccianiga, B; Cadonati, L; Calaprice, F; Carraro, C; Cavalcante, P; Chavarria, A; D'Angelo, D; Davini, S; Derbin, A; Etenko, A; Fomenko, K; Franco, D; Galbiati, C; Gazzana, S; Ghiano, C; Giammarchi, M; Goeger-Neff, M; Goretti, A; Grandi, L; Guardincerri, E; Hardy, S; Ianni, Aldo; Ianni, Andrea; Kobychev, V; Korablev, D; Korga, G; Koshio, Y; Kryn, D; Laubenstein, M; Lewke, T; Litvinovich, E; Loer, B; Lombardi, F; Lombardi, P; Ludhova, L; Machulin, I; Manecki, S; Maneschg, W; Manuzio, G; Meindl, Q; Meroni, E; Miramonti, L; Misiaszek, M; Montanari, D; Mosteiro, P; Muratova, V; Oberauer, L; Obolensky, M; Ortica, F; Pallavicini, M; Papp, L; Peña-Garay, C; Perasso, L; Perasso, S; Pocar, A; Raghavan, R S; Ranucci, G; Razeto, A; Re, A; Romani, A; Sabelnikov, A; Saldanha, R; Salvo, C; Schönert, S; Simgen, H; Skorokhvatov, M; Smirnov, O; Sotnikov, A; Sukhotin, S; Suvorov, Y; Tartaglia, R; Testera, G; Vignaud, D; Vogelaar, R B; von Feilitzsch, F; Winter, J; Wojcik, M; Wright, A; Wurm, M; Xu, J; Zaimidoroga, O; Zavatarelli, S; Zuzel, G

2011-09-30

The rate of neutrino-electron elastic scattering interactions from 862 keV (7)Be solar neutrinos in Borexino is determined to be 46.0±1.5(stat)(-1.6)(+1.5)(syst) counts/(day·100  ton). This corresponds to a ν(e)-equivalent (7)Be solar neutrino flux of (3.10±0.15)×10(9)  cm(-2) s(-1) and, under the assumption of ν(e) transition to other active neutrino flavours, yields an electron neutrino survival probability of 0.51±0.07 at 862 keV. The no flavor change hypothesis is ruled out at 5.0 σ. A global solar neutrino analysis with free fluxes determines Φ(pp)=6.06(-0.06)(+0.02)×10(10)  cm(-2) s(-1) and Φ(CNO)Mikheyev-Smirnov-Wolfenstein large mixing angle neutrino oscillation model is experimentally tested at low energy.

Magnetopause reconnection rate estimates for Jupiter's magnetosphere based on interplanetary measurements at ~5AU

Directory of Open Access Journals (Sweden)

J. D. Nichols

2006-03-01

Full Text Available We make the first quantitative estimates of the magnetopause reconnection rate at Jupiter using extended in situ data sets, building on simple order of magnitude estimates made some thirty years ago by Brice and Ionannidis (1970 and Kennel and Coroniti (1975, 1977. The jovian low-latitude magnetopause (open flux production reconnection voltage is estimated using the Jackman et al. (2004 algorithm, validated at Earth, previously applied to Saturn, and here adapted to Jupiter. The high-latitude (lobe magnetopause reconnection voltage is similarly calculated using the related Gérard et al. (2005 algorithm, also previously used for Saturn. We employ data from the Ulysses spacecraft obtained during periods when it was located near 5AU and within 5° of the ecliptic plane (January to June 1992, January to August 1998, and April to October 2004, along with data from the Cassini spacecraft obtained during the Jupiter flyby in 2000/2001. We include the effect of magnetospheric compression through dynamic pressure modulation, and also examine the effect of variations in the direction of Jupiter's magnetic axis throughout the jovian day and year. The intervals of data considered represent different phases in the solar cycle, such that we are also able to examine solar cycle dependency. The overall average low-latitude reconnection voltage is estimated to be ~230 kV, such that the average amount of open flux created over one solar rotation is ~500 GWb. We thus estimate the average time to replenish Jupiter's magnetotail, which contains ~300-500 GWb of open flux, to be ~15-25 days, corresponding to a tail length of ~3.8-6.5 AU. The average high-latitude reconnection voltage is estimated to be ~130 kV, associated with lobe "stirring". Within these averages, however, the estimated voltages undergo considerable variation. Generally, the low-latitude reconnection voltage exhibits a "background" of ~100 kV that is punctuated by one or two significant

Solar hot spots are still hot

International Nuclear Information System (INIS)

Bai, T.

1990-01-01

Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22. 14 refs

Molded polymer solar water heater

Science.gov (United States)

Bourne, Richard C.; Lee, Brian E.

2004-11-09

A solar water heater has a rotationally-molded water box and a glazing subassembly disposed over the water box that enhances solar gain and provides an insulating air space between the outside environment and the water box. When used with a pressurized water system, an internal heat exchanger is integrally molded within the water box. Mounting and connection hardware is included to provide a rapid and secure method of installation.

Mechanism of Cyclically Polarity Reversing Solar Magnetic Cycle as ...

Indian Academy of Sciences (India)

tribpo

solar dynamo mechanism that generates electric current and magnetic field by plasma flows ... rotating body in the Universe. We also mention a list ... verifications of any solar cycle dynamo theories of short and long term behaviors of the Sun, ...

Earth Rotation

Science.gov (United States)

Dickey, Jean O.

1995-01-01

The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.

Nonlinear two-fluid hydromagnetic waves in the solar wind: Rotational discontinuity, soliton, and finite-extent Alfven wave train solutions

International Nuclear Information System (INIS)

Lyu, L.H.; Kan, J.R.

1989-01-01

Nonlinear one-dimensional constant-profile hydromagnetic wave solutions are obtained in finite-temperature two-fluid collisionless plasmas under adiabatic equation of state. The nonlinear wave solutions can be classified according to the wavelength. The long-wavelength solutions are circularly polarized incompressible oblique Alfven wave trains with wavelength greater than hudreds of ion inertial length. The oblique wave train solutions can explain the high degree of alignment between the local average magnetic field and the wave normal direction observed in the solar wind. The short-wavelength solutions include rarefaction fast solitons, compression slow solitons, Alfven solitons and rotational discontinuities, with wavelength of several tens of ion inertial length, provided that the upstream flow speed is less than the fast-mode speed

Solar neutrinos and nonradial solar oscillations

International Nuclear Information System (INIS)

Zatsepin, G.T.; Gavryuseva, E.A.; Kopysov, Yu.S.

1980-01-01

The problem of origin of surface solar oscillations is considered. It is assumed that generation of oscillations is performed by the solar nucleus. The necessary excitation condition for gravitational oscillations of the solar nucleus is a sharp decrease of the oscillation amplitude outside the nucleus, where the nuclear reaction rates are small and only radiation losses are considerable. It is shown that the specific singularities of gravitational wave propagation in solar entrails permit to attain a significant reduction of the oscillation amplitude. The solar entrails can serve as an effective trap for gravitational waves, if the substance of the solar nucleus is close to the state of convectional equilibrium. In order that the g 1 quadrupole mode of the solar nucleus has a period of 2h 40 min and sharply decreases in the solar mantle, it is enough that only the external part of the solar nucleus is close to the state of convectional equilibrium. Closeness of the solar nucleus to the state of convectional equilibrium is an argument in favour of its periodic mixing. Periodic mixing of the solar nucleus can serve as a cause of a low counting rate of solar neutrinos in R.Davis chlorous detector

78 FR 29131 - Solar Star California XX, LLC; Supplemental Notice that Initial Market-Based Rate Filing Includes...

Science.gov (United States)

2013-05-17

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-1442-000] Solar Star California XX, LLC; Supplemental Notice that Initial Market-Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding, of Solar Star...

Effect of solar chimney inclination angle on space flow pattern and ventilation rate

Energy Technology Data Exchange (ETDEWEB)

Bassiouny, Ramadan; Korah, Nader S.A. [Department of Mechanical Power Engineering and Energy, Minia University, Minia 61111 (Egypt)

2009-02-15

The solar chimney is a simple and practical idea that is applied to enhance space natural ventilation. The chimney could be vertical or inclined. The chimney inclination angle is an important parameter that greatly affects space flow pattern and ventilation rate. In the present study, the effect of chimney inclination angle on air change per hour and indoor flow pattern was numerically and analytically investigated. A numerical simulation using Ansys, a FEM-based code, was used to predict flow pattern. Then the results were compared with published experimental measurements. A FORTRAN program was developed to iteratively solve the mathematical model that was obtained through an overall energy balance on the solar chimney. The analytical results showed that an optimum air flow rate value was achieved when the chimney inclination is between 45 and 70 for latitude of 28.4 . The numerically predicted flow pattern inside the space supports this finding. Moreover, in the present study a correlation to predict the air change per hour was developed. The correlation was tested within a solar intensity greater than or equal to 500 W/m{sup 2}, and chimney width from 0.1 m to 0.35 m for different inclination angles with acceptable values. (author)

The Hα Emission of Nearby M Dwarfs and its Relation to Stellar Rotation

Science.gov (United States)

Newton, Elisabeth R.; Irwin, Jonathan; Charbonneau, David; Berlind, Perry; Calkins, Michael L.; Mink, Jessica

2017-01-01

The high-energy emission from low-mass stars is mediated by the magnetic dynamo. Although the mechanisms by which fully convective stars generate large-scale magnetic fields are not well understood, it is clear that, as for solar-type stars, stellar rotation plays a pivotal role. We present 270 new optical spectra of low-mass stars in the Solar Neighborhood. Combining our observations with those from the literature, our sample comprises 2202 measurements or non-detections of Hα emission in nearby M dwarfs. This includes 466 with photometric rotation periods. Stars with masses between 0.1 and 0.6 M⊙ are well-represented in our sample, with fast and slow rotators of all masses. We observe a threshold in the mass-period plane that separates active and inactive M dwarfs. The threshold coincides with the fast-period edge of the slowly rotating population, at approximately the rotation period at which an era of rapid rotational evolution appears to cease. The well-defined active/inactive boundary indicates that Hα activity is a useful diagnostic for stellar rotation period, e.g., for target selection for exoplanet surveys, and we present a mass-period relation for inactive M dwarfs. We also find a significant, moderate correlation between LHα/Lbol and variability amplitude: more active stars display higher levels of photometric variability. Consistent with previous work, our data show that rapid rotators maintain a saturated value of LHα/Lbol. Our data also show a clear power-law decay in LHα/Lbol with Rossby number for slow rotators, with an index of -1.7 ± 0.1.

Measurements of Drag Coefficients and Rotation Rates of Free-Falling Helixes

KAUST Repository

Al-Omari, Abdulrhaman A.

2016-01-01

in water, glycerol and a mixture of 30% glycerol in water. That generated rotation due to helical angle in water. However, we observe the rotation disappear in glycerol. The movement of the solid helical shapes is imaged using a high-speed video camera

Global aspects of stream evolution in the solar wind

International Nuclear Information System (INIS)

Gosling, J.T.

1984-01-01

A spatially variable coronal expansion, when coupled with solar rotation, leads to the formation of high speed solar wind streams which evolve considerably with increasing heliocentric distance. Initially the streams steepen for simple kinematic reasons, but this steepening is resisted by pressure forces, leading eventually to the formation of forward-reverse shock pairs in the distant heliosphere. The basic physical processes responsible for stream steepening an evolution are explored and model calculations are compared with actual spacecraft observations of the process. The solar wind stream evolution problem is relatively well understood both observationally and theoretically. Tools developed in achieving this understanding should be applicable to other astrophysical systems where a spatially or temporally variable outflow is associated with a rotating object. 27 references, 13 figures

Solar Flux Deposition And Heating Rates In Jupiter's Atmosphere

Science.gov (United States)

Perez-Hoyos, Santiago; Sánchez-Lavega, A.

2009-09-01

We discuss here the solar downward net flux in the 0.25 - 2.5 µm range in the atmosphere of Jupiter and the associated heating rates under a number of vertical cloud structure scenarios focusing in the effect of clouds and hazes. Our numerical model is based in the doubling-adding technique to solve the radiative transfer equation and it includes gas absorption by CH4, NH3 and H2, in addition to Rayleigh scattering by a mixture of H2 plus He. Four paradigmatic Jovian regions have been considered (hot-spots, belts, zones and Polar Regions). The hot-spots are the most transparent regions with downward net fluxes of 2.5±0.5 Wm-2 at the 6 bar level. The maximum solar heating is 0.04±0.01 K/day and occurs above 1 bar. Belts and zones characterization result in a maximum net downward flux of 0.5 Wm-2 at 2 bar and 0.015 Wm-2 at 6 bar. Heating is concentrated in the stratospheric and tropospheric hazes. Finally, Polar Regions are also explored and the results point to a considerable stratospheric heating of 0.04±0.02 K/day. In all, these calculations suggest that the role of the direct solar forcing in the Jovian atmospheric dynamics is limited to the upper 1 - 2 bar of the atmosphere except in the hot-spot areas. Acknowledgments: This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07.

Fast Rotating solar-like stars using asteroseismic datasets

DEFF Research Database (Denmark)

A. García, R.; Ceillier, T.; Campante, T.

2011-01-01

The NASA Kepler mission is providing an unprecedented set of asteroseismic data. In particular, short-cadence lightcurves (~60s samplings), allow us to study solar-like stars covering a wide range of masses, spectral types and evolutionary stages. Oscillations have been observed in around 600 out...

Geology and photometric variation of solar system bodies with minor atmospheres: implications for solid exoplanets.

Science.gov (United States)

Fujii, Yuka; Kimura, Jun; Dohm, James; Ohtake, Makiko

2014-09-01

A reasonable basis for future astronomical investigations of exoplanets lies in our best knowledge of the planets and satellites in the Solar System. Solar System bodies exhibit a wide variety of surface environments, even including potential habitable conditions beyond Earth, and it is essential to know how they can be characterized from outside the Solar System. In this study, we provide an overview of geological features of major Solar System solid bodies with minor atmospheres (i.e., the terrestrial Moon, Mercury, the Galilean moons, and Mars) that affect surface albedo at local to global scale, and we survey how they influence point-source photometry in the UV/visible/near IR (i.e., the reflection-dominant range). We simulate them based on recent mapping products and also compile observed light curves where available. We show a 5-50% peak-to-trough variation amplitude in one spin rotation associated with various geological processes including heterogeneous surface compositions due to igneous activities, interaction with surrounding energetic particles, and distribution of grained materials. Some indications of these processes are provided by the amplitude and wavelength dependence of variation in combinations of the time-averaged spectra. We also estimate the photometric precision needed to detect their spin rotation rates through periodogram analysis. Our survey illustrates realistic possibilities for inferring the detailed properties of solid exoplanets with future direct imaging observations. Key Words: Planetary environments-Planetary geology-Solar System-Extrasolar terrestrial planets.

Phase space representation of neutron monitor count rate and atmospheric electric field in relation to solar activity in cycles 21 and 22.

Science.gov (United States)

Silva, H G; Lopes, I

Heliospheric modulation of galactic cosmic rays links solar cycle activity with neutron monitor count rate on earth. A less direct relation holds between neutron monitor count rate and atmospheric electric field because different atmospheric processes, including fluctuations in the ionosphere, are involved. Although a full quantitative model is still lacking, this link is supported by solid statistical evidence. Thus, a connection between the solar cycle activity and atmospheric electric field is expected. To gain a deeper insight into these relations, sunspot area (NOAA, USA), neutron monitor count rate (Climax, Colorado, USA), and atmospheric electric field (Lisbon, Portugal) are presented here in a phase space representation. The period considered covers two solar cycles (21, 22) and extends from 1978 to 1990. Two solar maxima were observed in this dataset, one in 1979 and another in 1989, as well as one solar minimum in 1986. Two main observations of the present study were: (1) similar short-term topological features of the phase space representations of the three variables, (2) a long-term phase space radius synchronization between the solar cycle activity, neutron monitor count rate, and potential gradient (confirmed by absolute correlation values above ~0.8). Finally, the methodology proposed here can be used for obtaining the relations between other atmospheric parameters (e.g., solar radiation) and solar cycle activity.

ARE GIANT TORNADOES THE LEGS OF SOLAR PROMINENCES?

Energy Technology Data Exchange (ETDEWEB)

Wedemeyer, Sven; Scullion, Eamon; Rouppe van der Voort, Luc; Bosnjak, Antonija [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Antolin, Patrick, E-mail: sven.wedemeyer@astro.uio.no [Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, bus 2400, B-3001 Leuven (Belgium)

2013-09-10

Observations in the 171 A channel of the Atmospheric Imaging Assembly of the space-borne Solar Dynamics Observatory show tornado-like features in the atmosphere of the Sun. These giant tornadoes appear as dark, elongated, and apparently rotating structures in front of a brighter background. This phenomenon is thought to be produced by rotating magnetic field structures that extend throughout the atmosphere. We characterize giant tornadoes through a statistical analysis of properties such as spatial distribution, lifetimes, and sizes. A total number of 201 giant tornadoes are detected in a period of 25 days, suggesting that, on average, about 30 events are present across the whole Sun at a time close to solar maximum. Most tornadoes appear in groups and seem to form the legs of prominences, thus serving as plasma sources/sinks. Additional H{alpha} observations with the Swedish 1 m Solar Telescope imply that giant tornadoes rotate as a structure, although they clearly exhibit a thread-like structure. We observe tornado groups that grow prior to the eruption of the connected prominence. The rotation of the tornadoes may progressively twist the magnetic structure of the prominence until it becomes unstable and erupts. Finally, we investigate the potential relation of giant tornadoes to other phenomena, which may also be produced by rotating magnetic field structures. A comparison to cyclones, magnetic tornadoes, and spicules implies that such events are more abundant and short-lived the smaller they are. This comparison might help to construct a power law for the effective atmospheric heating contribution as a function of spatial scale.

ARE GIANT TORNADOES THE LEGS OF SOLAR PROMINENCES?

International Nuclear Information System (INIS)

Wedemeyer, Sven; Scullion, Eamon; Rouppe van der Voort, Luc; Bosnjak, Antonija; Antolin, Patrick

2013-01-01

Observations in the 171 Å channel of the Atmospheric Imaging Assembly of the space-borne Solar Dynamics Observatory show tornado-like features in the atmosphere of the Sun. These giant tornadoes appear as dark, elongated, and apparently rotating structures in front of a brighter background. This phenomenon is thought to be produced by rotating magnetic field structures that extend throughout the atmosphere. We characterize giant tornadoes through a statistical analysis of properties such as spatial distribution, lifetimes, and sizes. A total number of 201 giant tornadoes are detected in a period of 25 days, suggesting that, on average, about 30 events are present across the whole Sun at a time close to solar maximum. Most tornadoes appear in groups and seem to form the legs of prominences, thus serving as plasma sources/sinks. Additional Hα observations with the Swedish 1 m Solar Telescope imply that giant tornadoes rotate as a structure, although they clearly exhibit a thread-like structure. We observe tornado groups that grow prior to the eruption of the connected prominence. The rotation of the tornadoes may progressively twist the magnetic structure of the prominence until it becomes unstable and erupts. Finally, we investigate the potential relation of giant tornadoes to other phenomena, which may also be produced by rotating magnetic field structures. A comparison to cyclones, magnetic tornadoes, and spicules implies that such events are more abundant and short-lived the smaller they are. This comparison might help to construct a power law for the effective atmospheric heating contribution as a function of spatial scale

Tokamak rotation and charge exchange

International Nuclear Information System (INIS)

Hazeltine, R.D.; Rowan, W.L.; Solano, E.R.; Valanju, P.M.

1991-01-01

In the absence of momentum input, tokamak toroidal rotation rates are typically small - no larger in particular than poloidal rotation - even when the radial electric field is strong, as near the plasma edge. This circumstance, contradicting conventional neoclassical theory, is commonly attributed to the rotation damping effect of charge exchange, although a detailed comparison between charge-exchange damping theory and experiment is apparently unavailable. Such a comparison is attempted here in the context of recent TEXT experiments, which compare rotation rates, both poloidal and toroidal, in helium and hydrogen discharges. The helium discharges provide useful data because they are nearly free of ion-neutral charge exchange; they have been found to rotate toroidally in reasonable agreement with neoclassical predictions. The hydrogen experiments show much smaller toroidal motion as usual. The theoretical calculation uses the full charge-exchange operator and assumes plateau collisionality, roughly consistent with the experimental conditions. The authors calculate the ion flow as a function of v cx /v c , where v cx is the charge exchange rate and v c the Coulomb collision frequency. The results are in reasonable accord with the observations. 1 ref

A novel rotational invariants target recognition method for rotating motion blurred images

Science.gov (United States)

Lan, Jinhui; Gong, Meiling; Dong, Mingwei; Zeng, Yiliang; Zhang, Yuzhen

2017-11-01

The imaging of the image sensor is blurred due to the rotational motion of the carrier and reducing the target recognition rate greatly. Although the traditional mode that restores the image first and then identifies the target can improve the recognition rate, it takes a long time to recognize. In order to solve this problem, a rotating fuzzy invariants extracted model was constructed that recognizes target directly. The model includes three metric layers. The object description capability of metric algorithms that contain gray value statistical algorithm, improved round projection transformation algorithm and rotation-convolution moment invariants in the three metric layers ranges from low to high, and the metric layer with the lowest description ability among them is as the input which can eliminate non pixel points of target region from degenerate image gradually. Experimental results show that the proposed model can improve the correct target recognition rate of blurred image and optimum allocation between the computational complexity and function of region.

The measurement of solar magnetic fields

International Nuclear Information System (INIS)

Stenflo, J.O.

1978-01-01

Solar activity is basically caused by the interaction between magnetic fields, solar rotation and convective motions. Detailed mapping of the Sun's rapidly varying magnetic field helps in the understanding of the mechanisms of solar activity. Observations in recent years have revealed unexpected and intriguing properties of solar magnetic fields, the explanation of which has become a challenge to plasma physicists. This review deals primarily with how the Sun's magnetic field is measured, but it also includes a brief review of the present observational picture of the magnetic field, which is needed to understand the problems of how to properly interpret the observations. 215 references. (author)

Vortex flows in the solar chromosphere. I. Automatic detection method

Science.gov (United States)

Kato, Y.; Wedemeyer, S.

2017-05-01

Solar "magnetic tornadoes" are produced by rotating magnetic field structures that extend from the upper convection zone and the photosphere to the corona of the Sun. Recent studies show that these kinds of rotating features are an integral part of atmospheric dynamics and occur on a large range of spatial scales. A systematic statistical study of magnetic tornadoes is a necessary next step towards understanding their formation and their role in mass and energy transport in the solar atmosphere. For this purpose, we develop a new automatic detection method for chromospheric swirls, meaning the observable signature of solar tornadoes or, more generally, chromospheric vortex flows and rotating motions. Unlike existing studies that rely on visual inspections, our new method combines a line integral convolution (LIC) imaging technique and a scalar quantity that represents a vortex flow on a two-dimensional plane. We have tested two detection algorithms, based on the enhanced vorticity and vorticity strength quantities, by applying them to three-dimensional numerical simulations of the solar atmosphere with CO5BOLD. We conclude that the vorticity strength method is superior compared to the enhanced vorticity method in all aspects. Applying the method to a numerical simulation of the solar atmosphere reveals very abundant small-scale, short-lived chromospheric vortex flows that have not been found previously by visual inspection.

Solar-terrestrial disturbances of June-September 1982, 2

International Nuclear Information System (INIS)

Kumagai, Hiroshi; Ohbu, Kouji; Ouchi, Choshichi; Isobe, Takeshi; Hori, Toshihiro; Ouchi, Eiji

1985-01-01

The outline of the solar activity during the period from June to September 1982 is given. During this period, several extremely developed active regions appeared on the solar disk and produced severe solar-terrestrial disturbances which we had not experienced since August 1972. In June and July, significant solar activities were brought about by the active regions 3763, 3776, and 3804. These regions frequently produced large flares of the highest class of importances in both Hsub(a) and X-ray intensities. However, the geomagnetic disturbances scarcely developed in June. The 3B/X7 flare on July 12 occurred in the region 3804 and caused the largest proton event and geomagnetic storm in this solar cycle. In August and September, flare occurrences were fewer than before. The 2B/M6 and 3N/M4 flares occurred in the region 3886 on September 4, and 2B/C9 flare occurred in the region 3907 on September 19. They are considered to cause two major geomagnetic storms which started on September 5 and 21, respectively. It seems remarkable that significant flares which occurred during these periods were produced by the same active region maintaining activities for more than ten solar rotations; 3776, 3804, and 3886 belonged to the same region in different solar rotations. (author)

Light-curve Modulation of Low-mass Stars in K2. I. Identification of 481 Fast Rotators in the Solar Neighborhood

Science.gov (United States)

Saylor, Dicy; Lepine, Sebastien; Crossfield, Ian; Petigura, Erik A.

2018-01-01

The K2 mission is targeting large numbers of nearby (d 40 mas yr‑1, V < 20). Additionally, the mission is targeting low-mass, high proper motion stars associated with the local (d < 500 pc) Galactic halo population also selected from SUPERBLINK. K2 campaigns 0 through 8 monitored a total of 26,518 of these cool main-sequence stars. We used the auto-correlation function to search for fast rotators by identifying short-period photometric modulations in the K2 light curves. We identified 481 candidate fast rotators with rotation periods <4 days that show light-curve modulations consistent with starspots. Their kinematics show low average transverse velocities, suggesting that they are part of the young disk population. A subset (13) of the fast rotators is found among those targets with colors and kinematics consistent with the local Galactic halo population and may represent stars spun up by tidal interactions in close binary systems. We further demonstrate that the M dwarf fast rotators selected from the K2 light curves are significantly more likely to have UV excess and discuss the potential of the K2 mission to identify new nearby young GKM dwarfs on the basis of their fast rotation rates. Finally, we discuss the possible use of local halo stars as fiducial, non-variable sources in the Kepler fields.

Helicity--vorticity turbulent pumping of magnetic fields in the solar dynamo

OpenAIRE

Pipin, V. V.

2012-01-01

The interaction of helical convective motions and differential rotation in the solar convection zone results in turbulent drift of a large-scale magnetic field. We discuss the pumping mechanism and its impact on the solar dynamo.

Quasi-biennial periodicity in the solar neutrino flux and its relation to the solar structure

International Nuclear Information System (INIS)

Sakurai, K.

1981-01-01

By analysing the observed results on the neutrino flux from the Sun for the years 1970-1978, it is shown that the production rate of the neutrinos at the central core of the Sun had been varying with a period almost equal to 26 months for these years. This so-called 'quasi-biennial' periodicity in this rate suggests that the physical state of the central core of the Sun must have been modulated with this period through the variation of physical parameters as temperature and the chemial composition at the central core of the Sun. An idea to interpret this observed periodicity is thus proposed by taking the variations of these parameters into consideration. Some supporting evidence on this periodicity can be found on the variations of the solar activity as the relative sunspot numbers and the equatorial rotation speed of the Sun. (orig.)

Evolutionary charts of solar activity (calcium plages) as functions of heliographic longitude and time

International Nuclear Information System (INIS)

Hedeman, E.R.; Dodson, H.W.; Roelof, E.C.

1981-08-01

The richness and diversity of data relating to solar activity present a challenge from the point of view of organization and evaluation. For phenomena such as plages and centers of activity that tend to last for more than one solar rotation, a sequence of evolutionary charts based on heliographic longitude for successive solar rotations are discussed. Such a diagrammatic representation of calcium plages as a function of longitude and time, coupled with considerations of heliographic latitude, permits relatively easy and confident recognition of successively returning centers of activity

Equations for solar tracking.

Science.gov (United States)

Merlaud, Alexis; De Mazière, Martine; Hermans, Christian; Cornet, Alain

2012-01-01

Direct sunlight absorption by trace gases can be used to quantify them and investigate atmospheric chemistry. In such experiments, the main optical apparatus is often a grating or a Fourier transform spectrometer. A solar tracker based on motorized rotating mirrors is commonly used to direct the light along the spectrometer axis, correcting for the apparent rotation of the Sun. Calculating the Sun azimuth and altitude for a given time and location can be achieved with high accuracy but different sources of angular offsets appear in practice when positioning the mirrors. A feedback on the motors, using a light position sensor close to the spectrometer, is almost always needed. This paper aims to gather the main geometrical formulas necessary for the use of a widely used kind of solar tracker, based on two 45° mirrors in altazimuthal set-up with a light sensor on the spectrometer, and to illustrate them with a tracker developed by our group for atmospheric research.

Equations for Solar Tracking

Directory of Open Access Journals (Sweden)

Alain Cornet

2012-03-01

Full Text Available Direct sunlight absorption by trace gases can be used to quantify them and investigate atmospheric chemistry. In such experiments, the main optical apparatus is often a grating or a Fourier transform spectrometer. A solar tracker based on motorized rotating mirrors is commonly used to direct the light along the spectrometer axis, correcting for the apparent rotation of the Sun. Calculating the Sun azimuth and altitude for a given time and location can be achieved with high accuracy but different sources of angular offsets appear in practice when positioning the mirrors. A feedback on the motors, using a light position sensor close to the spectrometer, is almost always needed. This paper aims to gather the main geometrical formulas necessary for the use of a widely used kind of solar tracker, based on two 45° mirrors in altazimuthal set-up with a light sensor on the spectrometer, and to illustrate them with a tracker developed by our group for atmospheric research.

Solar energy system with wind vane

Science.gov (United States)

Grip, Robert E

2015-11-03

A solar energy system including a pedestal defining a longitudinal axis, a frame that is supported by the pedestal and that is rotateable relative to the pedestal about the longitudinal axis, the frame including at least one solar device, and a wind vane operatively connected to the frame to urge the frame relative to the pedestal about the longitudinal axis in response to wind acting on the wind vane.

Solar Energy Deposition Rates in the Mesosphere Derived from Airglow Measurements: Implications for the Ozone Model Deficit Problem

Science.gov (United States)

Mlynczak, Martin G.; Garcia, Rolando R.; Roble, Raymond G.; Hagan, Maura

2000-01-01

We derive rates of energy deposition in the mesosphere due to the absorption of solar ultraviolet radiation by ozone. The rates are derived directly from measurements of the 1.27-microns oxygen dayglow emission, independent of knowledge of the ozone abundance, the ozone absorption cross sections, and the ultraviolet solar irradiance in the ozone Hartley band. Fifty-six months of airglow data taken between 1982 and 1986 by the near-infrared spectrometer on the Solar-Mesosphere Explorer satellite are analyzed. The energy deposition rates exhibit altitude-dependent annual and semi-annual variations. We also find a positive correlation between temperatures and energy deposition rates near 90 km at low latitudes. This correlation is largely due to the semiannual oscillation in temperature and ozone and is consistent with model calculations. There is also a suggestion of possible tidal enhancement of this correlation based on recent theoretical and observational analyses. The airglow-derived rates of energy deposition are then compared with those computed by multidimensional numerical models. The observed and modeled deposition rates typically agree to within 20%. This agreement in energy deposition rates implies the same agreement exists between measured and modeled ozone volume mixing ratios in the mesosphere. Only in the upper mesosphere at midlatitudes during winter do we derive energy deposition rates (and hence ozone mixing ratios) consistently and significantly larger than the model calculations. This result is contrary to previous studies that have shown a large model deficit in the ozone abundance throughout the mesosphere. The climatology of solar energy deposition and heating presented in this paper is available to the community at the Middle Atmosphere Energy Budget Project web site at http://heat-budget.gats-inc.com.

The solar sail: Current state of the problem

Science.gov (United States)

Polyakhova, Elena; Korolev, Vladimir

2018-05-01

Mathematical models of dynamics of the spacecraft with a solar sail to control orbital motion and rotation of the entire structureare considered. The movement of a spacecraftby a solar sail is based on the effect of light pressure. The magnitude and direction of the light pressure force vector is determined by the size and properties of the sail surface and the orientation angle relative to the sunlight flux. It is possible to vary the properties, sizes or locations of the sails to control the motion. Turning the elements of the sail, we get the opportunity to control the direction of the vector of the acting force and the moment with respect to the center of mass. Specificity of solar sail control is the interaction of orbital motion and rotational movements of the entire structure, which could provide the desired orientation and stability at small perturbations. The solar sail can be used for flights to the major planets, to meet with asteroids and comet, to realize a special desired motion in the neighborhood of the Sun or near the Earth.

Solar-forced diurnal regulation of cave drip rates via phreatophyte evapotranspiration

Directory of Open Access Journals (Sweden)

K. Coleborn

2016-11-01

Full Text Available We present results of a detailed study of drip rate variations at 12 drip discharge sites in Glory Hole Cave, New South Wales, Australia. Our novel time series analysis, using the wavelet synchrosqueezed transform, reveals pronounced oscillations at daily and sub-daily frequencies occurring in 8 out of the 12 monitored sites. These oscillations were not spatially or temporally homogenous, with different drip sites exhibiting such behaviour at different times of year in different parts of the cave. We test several hypotheses for the cause of the oscillations, including variations in pressure gradients between karst and cave due to cave breathing effects or atmospheric and earth tides, variations in hydraulic conductivity due to changes in viscosity of water with daily temperature oscillations, and solar-driven daily cycles of vegetative (phreatophytic transpiration. We conclude that the only hypothesis consistent with the data and hydrologic theory is that daily oscillations are caused by solar-driven pumping by phreatophytic trees which are abundant at the site. The daily oscillations are not continuous and occur sporadically in short bursts (2–14 days throughout the year due to non-linear modification of the solar signal via complex karst architecture. This is the first indirect observation leading to the hypothesis of tree water use in cave drip water. It has important implications for karst hydrology in regards to developing a new protocol to determine the relative importance of trends in drip rate, such as diurnal oscillations, and how these trends change over timescales of weeks to years. This information can also be used to infer karst architecture. This study demonstrates the importance of vegetation on recharge dynamics, information that will inform both process-based karst models and empirical estimation approaches. Our findings support a growing body of research exploring the impact of trees on speleothem paleoclimate proxies.

Quantitative rotating frame relaxometry methods in MRI.

Science.gov (United States)

Gilani, Irtiza Ali; Sepponen, Raimo

2016-06-01

Macromolecular degeneration and biochemical changes in tissue can be quantified using rotating frame relaxometry in MRI. It has been shown in several studies that the rotating frame longitudinal relaxation rate constant (R1ρ ) and the rotating frame transverse relaxation rate constant (R2ρ ) are sensitive biomarkers of phenomena at the cellular level. In this comprehensive review, existing MRI methods for probing the biophysical mechanisms that affect the rotating frame relaxation rates of the tissue (i.e. R1ρ and R2ρ ) are presented. Long acquisition times and high radiofrequency (RF) energy deposition into tissue during the process of spin-locking in rotating frame relaxometry are the major barriers to the establishment of these relaxation contrasts at high magnetic fields. Therefore, clinical applications of R1ρ and R2ρ MRI using on- or off-resonance RF excitation methods remain challenging. Accordingly, this review describes the theoretical and experimental approaches to the design of hard RF pulse cluster- and adiabatic RF pulse-based excitation schemes for accurate and precise measurements of R1ρ and R2ρ . The merits and drawbacks of different MRI acquisition strategies for quantitative relaxation rate measurement in the rotating frame regime are reviewed. In addition, this review summarizes current clinical applications of rotating frame MRI sequences. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Evaluation of a tracking flat-plate solar collector in Brazil

International Nuclear Information System (INIS)

Maia, Cristiana B.; Ferreira, André G.; Hanriot, Sérgio M.

2014-01-01

The continuing research for an alternative power source due to the perceived scarcity of fuel fossils has, in recent years, given solar energy a remarkable edge. Nevertheless, the Earth's daily and seasonal movement affects the intensity of the incident solar radiation. Devices can track the sun in order to ensure optimum positions with regard to incident solar radiation, maximizing the absorbed solar energy, and the useful energy gain. In this paper, a mathematical model is developed to estimate the solar radiation absorbed, the useful energy gain, and the efficiency of a flat-plate solar collector in Brazil. The results for a sun tracking flat-plate solar collector were compared to fixed devices. The full tracking system with rotation about two axes presented higher absorbed energy, when compared to the rotation about a single axe and to a fixed collector. Also, it was shown that the tilt angle for a fixed solar collector does not cause significant variations in the useful energy gain or in the absorbed solar radiation, for the same azimuth angle. - Highlights: • A model was developed for solar radiation based on experimental data for K T . • Useful energy gain and efficiency of a flat-plate solar collector were evaluated for a one-year period. • Several sun tracking systems were compared to fixed devices. • Tilt angle for a fixed device does not significantly affect the useful energy gain

The relationship between solar activity and the H and K line cores in integrated sunlight

International Nuclear Information System (INIS)

Jebsen, D.E.; Mitchell, W.E. Jr.

1978-01-01

In this paper the authors present and analyze new data on the cores of the H and K lines of ionized calcium in the spectrum of integrated sunlight. The intensities of the components Hsub(2γ), H 3 , Hsub(2r), Ksub(2γ), K 3 , and Ksub(2r) in the line cores were measured in terms of the continuum intensity at 4000 A during a solar rotation in September 1969. Other data on these components, obtained at or close to the time of solar minimum (September 1964) and solar maximum (September 1968), were also included. The intensities of these features are compared with two indices of solar activity: the Ca II plage index and the 2800 MHZ signal. The average correlation coefficients between the intensities of the measured features and those indices were 0.69 and 0.64, respectively. The results are consistent with those of Bumba and Ruzickova-Topolova (1967) for a solar rotation period in 1965. The method and results should provide a detailed quantitative basis for the study of the activity cycles and rotation periods of solar-type stars. (Auth.)

Two Solar Tornadoes Observed with the Interface Region Imaging Spectrograph

Science.gov (United States)

Yang, Zihao; Tian, Hui; Peter, Hardi; Su, Yang; Samanta, Tanmoy; Zhang, Jingwen; Chen, Yajie

2018-01-01

The barbs or legs of some prominences show an apparent motion of rotation, which are often termed solar tornadoes. It is under debate whether the apparent motion is a real rotating motion, or caused by oscillations or counter-streaming flows. We present analysis results from spectroscopic observations of two tornadoes by the Interface Region Imaging Spectrograph. Each tornado was observed for more than 2.5 hr. Doppler velocities are derived through a single Gaussian fit to the Mg II k 2796 Å and Si IV 1393 Å line profiles. We find coherent and stable redshifts and blueshifts adjacent to each other across the tornado axes, which appears to favor the interpretation of these tornadoes as rotating cool plasmas with temperatures of 104 K–105 K. This interpretation is further supported by simultaneous observations of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, which reveal periodic motions of dark structures in the tornadoes. Our results demonstrate that spectroscopic observations can provide key information to disentangle different physical processes in solar prominences.

The Effect of the Volume Flow rate on the Efficiency of a Solar Collector

DEFF Research Database (Denmark)

Fan, Jianhua; Shah, Louise Jivan; Furbo, Simon

rates. Theoretically, a simplified model of the solar collector panel is built by means of the CFD (Computational Fluid Dynamics) code Fluent, where the geometry of the collector panel except the casing is fully modeled. Both lateral and longitudinal heat conduction in the absorber fins, the heat...... transfer from the absorber to the solar collector fluid and the heat loss from the absorber are considered. Flow and temperature distribution in the collector panel are investigated with buoyancy effect. Measurements are carried out with the solar collector panel. Collector efficiencies are measured......The flow distribution inside a collector panel with an area of 12.5 m² and with 16 parallel connected horizontal fins and the effect of the flow nonuniformity on the risk of boiling and on the collector efficiency have been theoretically and experimentally investigated for different volume flow...

Exciting a rotating mass on a spring without change to its rotation rate

International Nuclear Information System (INIS)

Kenyon, Kern E.

2001-01-01

An exact mathematical solution, in terms of elementary functions, is presented for the two-dimensional problem of a mass rotating on a linear spring. The two governing equations in polar coordinates are nonlinear, coupled ordinary differential equations, but they can be solved analytically in sequence. In general, the orbit of the mass is an ellipse with the fixed end of the spring located at the centre of the ellipse. The orbital frequency is identical to the natural frequency of the spring and it is independent of the amplitude of the motion (independent of the major and minor axes of the ellipse). Based on the solution the following claim is made. No matter how the mass is perturbed, within its plane of motion, the orbital frequency will remain constant. The disturbance can be infinitesimal or finite and it can cause either the total energy or the angular momentum of the system or both to increase or decrease but the orbital period will not change. It follows from the fixed end of the spring being at the ellipse's centre that the radial vibration of the mass has twice the natural frequency of the spring; i.e. two maxima and minima in one orbital period, which is not possible unless there is rotation. (author)

A model of the solar cycle driven by the dynamo action of the global convection in the solar convection zone

International Nuclear Information System (INIS)

Yoshimura, H.

1976-01-01

Extensive numerical studies of the dynamo equations due to the global convection are presented to simulate the solar cycle and to open the way to study general stellar magnetic cycles. The dynamo equations which represent the longitudinally-averaged magnetohydrodynamical action (mean magnetohydrodynamics) of the global convection under the influence of the rotation in the solar convection zone are considered here as an initial boundary-value problem. The latitudinal and radial structure of the dynamo action consisting of a generation action due to the differential rotation and a regeneration action due to the global convection is parameterized in accordance with the structure of the rotation and of the global convection. This is done especially in such a way as to represent the presence of the two cells of the regeneration action in the radial direction in which the action has opposite signs, which is typical of the regeneration action of the global convection. The effects of the dynamics of the global convection (e.g., the effects of the stratification of the physical conditions in the solar convection zone) are presumed to be all included in those parameters used in the model and they are presumed not to alter the results drastically since these effects are only to change the structure of the regeneration action topologically. (Auth.)

New picture for the internal rotation of the sun

International Nuclear Information System (INIS)

Morrow, C.A.

1988-01-01

For the last decade, solar-acoustic oscillations have been used to probe the physical properties of the solar interior. The endeavor is called helioseismology and is based on the fact that shifts in the frequency of an oscillation mode, as observed at the surface, contain information about the physical environment in those regions of the interior where the oscillation has energy. The thesis describes a helioseismic quest to determine the angular velocity inside the Sun as a function of depth and latitude. The author has analyzed rotational frequency splittings extracted from 15 days of full-disk observations of the solar-acoustic oscillations (l=15-99) obtained with the Fourier Tachometer (a Doppler analyzing instrument designed by Tim Brown). The observed frequency splittings are compared to those generated by several different physically-motivated models for the solar internal angular velocity

Solar wind energy transfer through the magnetopause of an open magnetosphere

International Nuclear Information System (INIS)

Lee, L.C.; Roederer, J.G.

1982-01-01

An expression for the total power P/sub T/ transferred from the solar wind to an ''open'' magnetopause with a nonzero normal component of the magnetic field, which is identified as a rotational discontinuity. The total power P/sub T/ consists of (1) the power P/sub EM/ representing the electromagnetic energy transfer and (2) the power P/sub KE/ representing the rate of kinetic energy carried by particles penetrating into the magnetosphere. It is found that P/sub EM/approx. =V/sub SW/ B/sub SW/psi, P/sub KE/approx. =(1/2 M/sub A/-1) P/sub EM/ and P/sub T/approx. =1/2M/sub A/P/sub EM/, where V/sub SW/, B/sub SW/, and M/sub A/ are the velocity, magnetic field, and the Alfven--Mach number in the solar wind, respectively, and Psi is the open magnetic flux in the magnetosphere. The Alfven--Mach number of flow at the magnetopause determines the nature of the local energy transfer; the power per unit area transferred from the solar wind to the magnetosphere consists mainly of kinetic energy. The electromagnetic energy rate P/sub EM/ controls the near-earth magnetospheric activity, whereas the kinetic energy rate P/sub KE/(approx. =3--4 P/sub EM/) should dominate the dynamics of the distant magnetotail

Incident solar radiation and coronary heart disease mortality rates in Europe

International Nuclear Information System (INIS)

Wong, Alfred

2008-01-01

The reported low mortality rate from coronary heart disease in Portugal, Spain, Italy, Greece, and France, to a lesser extent, has been attributed in numerous nutritional studies to the consumption of a Mediterranean-type diet. There are still many unresolved issues about the direct causal effect of the Mediterranean dietary regime on low incidence of coronary heart disease. An analysis of coronary heart disease mortality rates in Europe from a latitudinal gradient perspective has shown to have a close correlation to incident solar radiation. It is surmised that the resulting increased in situ biosynthesis of Vitamin D 3 could be the critical missing confounder in the analysis of the beneficial health outcome of the Mediterranean diet

Non-photic solar associations of heart rate variability and myocardial infarction

Science.gov (United States)

Cornélissen, Germaine; Halberg, Franz; Breus, Tamara; Syutkina, Elena V.; Baevsky, Roman; Weydahl, Andi; Watanabe, Yoshihiko; Otsuka, Kuniaki; Siegelova, Jarmila; Fiser, Bohumil; Bakken, Earl E.

2002-03-01

Alignment of serial epidemiological, physiological, including electrocardiographic data with variations in galactic cosmic rays, geomagnetic activity, and atmospheric pressure suggests the possibility of links among these physical environmental variations and health risks, such as myocardial infarctions and ischemic strokes, among others. An increase in the incidence of myocardial infarction in association with magnetic storms, reported by several investigators from Russia, Israel, Italy and Mexico, accounts in Minnesota for a 5% (220cases/year) increase in mortality during years of maximal solar activity by comparison with years of minimal solar activity. Magnetic storms are also found to decrease heart rate variability (HRV), indicating a possible mechanism since a reduced HRV is a prognostic factor for coronary artery disease and myocardial infarction. Longitudinal electrocardiographic monitoring for a week or much longer spans in different geographic locations, notably in the auroral oval, further suggests that the decrease in HRV affects spectral regions other than that around 3.6s (0.15-0.40Hz), reportedly associated with the parasympathetic nervous system. Differences in some associations are observed from solar cycle to solar cycle, and as a function of solar cycle stage, a finding resolving controversies. Coordinated physiological and physical monitoring, the scope of an international project on the Biosphere and the Cosmos, seeks reference values for a better understanding of environmental effects on human health and for testing the merit of space weather reports that could prompt countermeasures in space and on earth. Physiological data being collected systematically worldwide and morbidity/mortality statistics from causes such as myocardial infarction and stroke constitute invaluable data bases for assessing changes within the physiological range, for detecting environmental effects and for recognizing endogenous as well as exogenous disease

THE H α EMISSION OF NEARBY M DWARFS AND ITS RELATION TO STELLAR ROTATION

International Nuclear Information System (INIS)

Newton, Elisabeth R.; Irwin, Jonathan; Charbonneau, David; Berlind, Perry; Calkins, Michael L.; Mink, Jessica

2017-01-01

The high-energy emission from low-mass stars is mediated by the magnetic dynamo. Although the mechanisms by which fully convective stars generate large-scale magnetic fields are not well understood, it is clear that, as for solar-type stars, stellar rotation plays a pivotal role. We present 270 new optical spectra of low-mass stars in the Solar Neighborhood. Combining our observations with those from the literature, our sample comprises 2202 measurements or non-detections of H α emission in nearby M dwarfs. This includes 466 with photometric rotation periods. Stars with masses between 0.1 and 0.6 M ⊙ are well-represented in our sample, with fast and slow rotators of all masses. We observe a threshold in the mass–period plane that separates active and inactive M dwarfs. The threshold coincides with the fast-period edge of the slowly rotating population, at approximately the rotation period at which an era of rapid rotational evolution appears to cease. The well-defined active/inactive boundary indicates that H α activity is a useful diagnostic for stellar rotation period, e.g., for target selection for exoplanet surveys, and we present a mass-period relation for inactive M dwarfs. We also find a significant, moderate correlation between L Hα / L bol and variability amplitude: more active stars display higher levels of photometric variability. Consistent with previous work, our data show that rapid rotators maintain a saturated value of L Hα / L bol . Our data also show a clear power-law decay in L Hα / L bol with Rossby number for slow rotators, with an index of −1.7 ± 0.1.

Different parameter and technique affecting the rate of evaporation on active solar still -a review

Science.gov (United States)

A, Muthu Manokar; D, Prince Winston; A. E, Kabeel; Sathyamurthy, Ravishankar; T, Arunkumar

2018-03-01

Water is one of the essential sources for the endurance of human on the earth. As earth having only a small amount of water resources for consumption purpose people in rural and urban areas are getting affected by consuming dirty water that leads to water-borne diseases. Even though ground water is available in small quantity, it has to be treated properly before its use for internal consumption. Brackish water contains dissolve and undissolved contents, and hence it is not suitable for the household purpose. Nowadays, distillation process is done by using passive and active solar stills. The major problem in using passive solar still is meeting higher demand for fresh water. The fresh water production from passive solar still is critically low to meet the demand. To improve the productivity of conventional solar still, input feed water is preheated by integrating the solar still to different collector panels. In this review article, the different parameters that affect the rate of evaporation in an active solar still and the different methods incorporated has been presented. In addition to active distillation system, forced convection technique can be incorporated to increase the yield of fresh water by decreasing the temperature of cover. Furthermore, it is identified that the yield of fresh water from the active desalination system can be improved by sensible and latent heat energy storage. This review will motivate the researchers to decide appropriate active solar still technology for promoting development.

The effects of time, temperature and rotation of water on the corrosion rate of different types of steels

International Nuclear Information System (INIS)

Muhamad Daud; Jamaliah Shariff.

1984-01-01

By using hot plate/magnetic stirrer and immersion technique, the steel corroded uniformly and their corrosion rates vary due to type of steel, time of immersion, temperature and rotation of water. Therefore the rate of general corrosion, or sealing, of steel alloys is influenced by a number of factors, those best established being the composition of the metal, time, temperature, velocity, cleanliness or roughness of the metal surface and direct contact with solutions of the other materials. (author)

Evaluation of the Effect of Rotation and Application Rate of Nitrogen on Yield, Yield Components and Nitrogen Efficiency Indexes in wheat

Directory of Open Access Journals (Sweden)

R Nasri

2016-02-01

seeding rate of 200 kg ha-1. Soil samples were collected after harvest of each crop from 0 to 30 cm and 31 to 60 cm soil depths using a soil auger. Wheat grain yield (according to 14% moisture obtained by harvesting the central area of 3 in 10 m in each plot. Yield components were determined from two randomly selected areas (2m2 within each plot. Plant samples collected at harvest were separated into grain and straw and oven-dried at 60˚C for 72hr. Biomass and grain sub samples analyzed for total N content using a micro-Kjeldahl digestion with sulfuric acid. The terminology of N efficiency parameters was considered according to Delogu et al, (11 and Lopez-Bellido & Lopez-Bellido, (22, Rahimizadeh et al. (30, Limon-Ortega et al. (20 methods. Results and Discussion The results showed that there were highly significant differences (P ≤ 0.01 in forage yield. There were also significant differences (P ≤ 0.05 in total dry weight, protein content and protein yield between treatments. Perko varieties produced higher fresh and dry matter yield with 69,586 (kg ha-1 and 7147 (kg ha-1, respectively compared to other varieties. Buko varieties showed greater protein percentage with 23.36 compared to the rest of the varieties. The highest and lowest grain yield, with 8345, and 4491 (kg ha-1 were obtained for Buko; wheat rotation and fallow, wheat rotation, respectively. The highest and lowest nitrogen uptake was obtained for Buko; wheat and clover, wheat rotation, respectively. The differences between the rotations were significant for various agronomic nitrogen efficiency. The rotation of oilseed radish and wheat showed greater nitrogen economic performance with 36.20 kg ha-1. By increasing nitrogen rate agronomic performance decreased with the exception in fallow- wheat. Physiological efficiency of nitrogen in fallow-wheat rotation was more than 39 (kg kg-1 of nitrogen. The maximum efficiency of nitrogen recovery was obtained for oilseed radish: wheat and Perko PVH; wheat

Semi-analytical study of the rotational motion stability of artificial satellites using quaternions

International Nuclear Information System (INIS)

Dos Santos, Josué C; Zanardi, Maria Cecília; Matos, Nicholas

2013-01-01

This study at aims performing the stability analysis of the rotational motion to artificial satellites using quaternions to describe the satellite attitude (orientation on the space). In the system of rotational motion equations, which is composed by four kinematic equations of the quaternions and by the three Euler equations in terms of the rotational spin components. The influence of the gravity gradient and the direct solar radiation pressure torques have been considered. Equilibrium points were obtained through numerical simulations using the softwares Matlab and Octave, which are then analyzed by the Routh-Hurwitz Stability Criterion

Seismology and geodesy of the sun: Solar geodesy.

Science.gov (United States)

Dicke, R H

1981-03-01

Measurements of the elliptical figure of the sun made in 1966 are analyzed on an hourly basis. This analysis yields an improved measure of the previously found solar distortion, rotating rigidly with a sidereal period of 12.38+/-0.10 days. It also yields a set of residùals used to search for signals due to low-frequency solar oscillations.

The impact of water vapor transmission rate on the lifetime of flexible polymer solar cells

Science.gov (United States)

Hauch, Jens A.; Schilinsky, Pavel; Choulis, Stelios A.; Rajoelson, Sambatra; Brabec, Christoph J.

2008-09-01

In this paper we perform accelerated lifetime testing on high efficiency flexible poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PCBM) solar cells encapsulated with food package quality barrier films with a water vapor transmission rate of 0.2 g/(m2 day) at 65 °C/85% relative humidity. We show that lifetimes exceeding 1250 h, even at high temperature/high humidity conditions, may be reached, proving that organic solar cells are significantly less sensitive against the environmental effects of water and oxygen than previously expected.

The Effect of Cumulus Cloud Field Anisotropy on Domain-Averaged Solar Fluxes and Atmospheric Heating Rates

Science.gov (United States)

Hinkelman, Laura M.; Evans, K. Franklin; Clothiaux, Eugene E.; Ackerman, Thomas P.; Stackhouse, Paul W., Jr.

2006-01-01

Cumulus clouds can become tilted or elongated in the presence of wind shear. Nevertheless, most studies of the interaction of cumulus clouds and radiation have assumed these clouds to be isotropic. This paper describes an investigation of the effect of fair-weather cumulus cloud field anisotropy on domain-averaged solar fluxes and atmospheric heating rate profiles. A stochastic field generation algorithm was used to produce twenty three-dimensional liquid water content fields based on the statistical properties of cloud scenes from a large eddy simulation. Progressively greater degrees of x-z plane tilting and horizontal stretching were imposed on each of these scenes, so that an ensemble of scenes was produced for each level of distortion. The resulting scenes were used as input to a three-dimensional Monte Carlo radiative transfer model. Domain-average transmission, reflection, and absorption of broadband solar radiation were computed for each scene along with the average heating rate profile. Both tilt and horizontal stretching were found to significantly affect calculated fluxes, with the amount and sign of flux differences depending strongly on sun position relative to cloud distortion geometry. The mechanisms by which anisotropy interacts with solar fluxes were investigated by comparisons to independent pixel approximation and tilted independent pixel approximation computations for the same scenes. Cumulus anisotropy was found to most strongly impact solar radiative transfer by changing the effective cloud fraction, i.e., the cloud fraction when the field is projected on a surface perpendicular to the direction of the incident solar beam.

Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

Science.gov (United States)

Sittler, E.; Cooper, J.; Simpson, D.; Paterson, W.

2012-01-01

We present the present status of an investigation of the rotation rate of Saturn 's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. (2005) [1] for SOI and similar to that used by Thomsen et al. (2010). This technique allows one to nearly cover the full energy range of the CAPS IMS from 1 V less than or equal to E/Q less than 50 kV. Since our technique maps the observations into a local inertial frame, it does work during roll manoeuvres. We have made comparisons with Wilson et al. (2008) [2] (2005-358 and 2005-284) who performs a bi-Maxwellian fit to the ion singles data and our results are nearly identical. We will also make comparisons with results by Thomsen et al. (2010) [3]. Our analysis uses ion composition data to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. Since our analysis is a velocity moments technique it will work within the inner magnetosphere where pickup ions are important and velocity distributions are non-Maxwellian. So, we will present results inside Enceladus' L shell and determine if mass loading is important. In the future we plan to make comparisons with magnetic field observations, use Saturn ionosphere conductivities as

SPIN–SPIN COUPLING IN THE SOLAR SYSTEM

International Nuclear Information System (INIS)

Batygin, Konstantin; Morbidelli, Alessandro

2015-01-01

The richness of dynamical behavior exhibited by the rotational states of various solar system objects has driven significant advances in the theoretical understanding of their evolutionary histories. An important factor that determines whether a given object is prone to exhibiting non-trivial rotational evolution is the extent to which such an object can maintain a permanent aspheroidal shape, meaning that exotic behavior is far more common among the small body populations of the solar system. Gravitationally bound binary objects constitute a substantial fraction of asteroidal and TNO populations, comprising systems of triaxial satellites that orbit permanently deformed central bodies. In this work, we explore the rotational evolution of such systems with specific emphasis on quadrupole–quadrupole interactions, and show that for closely orbiting, highly deformed objects, both prograde and retrograde spin–spin resonances naturally arise. Subsequently, we derive capture probabilities for leading order commensurabilities and apply our results to the illustrative examples of (87) Sylvia and (216) Kleopatra asteroid systems. Cumulatively, our results suggest that spin–spin coupling may be consequential for highly elongated, tightly orbiting binary objects

SPIN–SPIN COUPLING IN THE SOLAR SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Batygin, Konstantin [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Morbidelli, Alessandro, E-mail: kbatygin@gps.caltech.edu [Departement Lagrange, Observatoire de la Côte d’Azur, F-06304 Nice (France)

2015-09-10

The richness of dynamical behavior exhibited by the rotational states of various solar system objects has driven significant advances in the theoretical understanding of their evolutionary histories. An important factor that determines whether a given object is prone to exhibiting non-trivial rotational evolution is the extent to which such an object can maintain a permanent aspheroidal shape, meaning that exotic behavior is far more common among the small body populations of the solar system. Gravitationally bound binary objects constitute a substantial fraction of asteroidal and TNO populations, comprising systems of triaxial satellites that orbit permanently deformed central bodies. In this work, we explore the rotational evolution of such systems with specific emphasis on quadrupole–quadrupole interactions, and show that for closely orbiting, highly deformed objects, both prograde and retrograde spin–spin resonances naturally arise. Subsequently, we derive capture probabilities for leading order commensurabilities and apply our results to the illustrative examples of (87) Sylvia and (216) Kleopatra asteroid systems. Cumulatively, our results suggest that spin–spin coupling may be consequential for highly elongated, tightly orbiting binary objects.

Analysis of failed rotator cuff repair – Retrospective survey of revisions after open rotator cuff repair

Directory of Open Access Journals (Sweden)

Rupert Schupfner

2017-07-01

Full Text Available Background Rotator cuff defects are frequently occurring shoulder pathologies associated with pain and movement impairment. Aims The aim of the study was to analyse the pathologies that lead to operative revisions after primary open rotator cuff repair. Methods In 216 patients who underwent primary rotator cuff repair and later required operative revision between 1996 to 2005, pathologies found intraoperatively during the primary operation and during revision surgery were collected, analysed and compared. Results The average age at the time of revision surgery was 54.3 years. The right shoulder (61.6 per cent was more often affected than the left, males (63.4 per cent more often than females. At primary operation – apart from rotator cuff repair – there were the following surgical procedures performed: 190 acromioplasty, 86 Acromiclavicular joint resections, 68 tenodesis, 40 adhesiolysis and 1 tenotomy. If an ACJ-resection had been performed in the primary operation, ACJ-problems were rare in revision surgery (p<0.01. Primary gleno-humeral adhesions were associated with a significant rise in re-tearing rate (p=0.049. Primary absence of adhesions went along with a significant lower rate of adhesions found at revision (p=0.018. Primary performed acromioplasty had no influence on re-tearing rate (p=0.408 or on the rate of subacromial impingement at revision surgery (p=0.709. Conclusion To avoid operative revision after rotator cuff repair relevant copathologies of the shoulder have to be identified before or during operation and treated accordingly. Therefore, even during open rotator cuff repair, the surgeon should initially start with arthroscopy of the shoulder joint and subacromial space to recognise co-pathologies.

Rating of roofs’ surfaces regarding their solar potential and suitability for PV systems, based on LiDAR data

International Nuclear Information System (INIS)

Lukač, Niko; Žlaus, Danijel; Seme, Sebastijan; Žalik, Borut; Štumberger, Gorazd

2013-01-01

Highlights: ► A new method for estimating and rating buildings roofs’ solar potential is presented. ► Considering LiDAR geospatial data together with pyranometer measurements. ► Use of multi-resolution shadowing model with new heuristic vegetation shadowing. ► High correlation between estimated solar potential and onsite measurements. -- Abstract: The roof surfaces within urban areas are constantly attracting interest regarding the installation of photovoltaic systems. These systems can improve self-sufficiency of electricity supply, and can help to decrease the emissions of greenhouse gases throughout urban areas. Unfortunately, some roof surfaces are unsuitable for installing photovoltaic systems. This presented work deals with the rating of roof surfaces within urban areas regarding their solar potential and suitability for the installation of photovoltaic systems. The solar potential of a roof’s surface is determined by a new method that combines extracted urban topography from LiDAR data with the pyranometer measurements of global and diffuse solar irradiances. Heuristic annual vegetation shadowing and a multi-resolution shadowing model, complete the proposed method. The significance of different influential factors (e.g. shadowing) was analysed extensively. A comparison between the results obtained by the proposed method and measurements performed on an actual PV power plant showed a correlation agreement of 97.4%.

C II forbidden-line 158 micron mapping in Sagittarius A Rotation curve and mass distribution in the galactic center

Science.gov (United States)

Lugten, J. B.; Genzel, R.; Crawford, M. K.; Townes, C. H.

1986-01-01

Based on data obtained with the NASA Kuiper Airborne Observatory 91.4 cm telescope, the 158-micron fine structure line emission of C(+) is mapped near the galactic center. The strongest emission comes from a 10-pc FWHM diameter disk centered on Sgr A West whose dominant motion is rotation. Extended C(+) emission is also found from the +50 km/s galactic center molecular cloud, and a second cloud at v(LSR) of about -35 km/s. The rotation curve and mass distribution within 10 pc of the galactic center are derived, and the C(+) profiles show a drop-off of rotation velocity between 2 and 10 pc. A mass model is suggested with 2-4 million solar masses in a central point mass, and a M/L ratio of the central stellar cluster of 0.5 solar masses/solar luminosities, suggesting a large abundance of giants and relatively recent star formation in the center.

Economic feasibility of a solar still desalination system with enhanced productivity

KAUST Repository

Ayoub, George M.

2014-02-01

Solar still desalination systems offer sustainable tools for fresh water production. However, their widespread application is often hindered by their relatively low production rates compared to other desalination methods. In this study, a simple amendment, in the form of a slowly-rotating hollow cylinder, was introduced within the solar still, significantly increasing the evaporative surface area. This new modified still was analyzed in terms of both operation and economic feasibility. The introduced cylinder resulted in a 200-300% increase in water output relative to a control, which did not include the cylinder. The resulting percent improvement far exceeds that obtained by other modifications. Unit production cost estimates varied between 6 and 60$/m3 depending on discount rates, productivity, service lifetime and initial capital costs. These projections are well within reported cost ranges for renewable-based technologies. In order to evaluate the system\\'s feasibility in real market value, different scenarios that introduce carbon-trading schemes and environmental degradation costs for fuel-based desalination, were performed. Reported costs for fuel-based brackish water and seawater desalination were thus adjusted to include unaccounted-for costs related to environmental damage. This analysis yielded results that further justify the economic feasibility of the new modified solar still, particularly for seawater desalination. © 2013 Elsevier B.V.

Longitudinal distribution of recurrent solar activity sources and its reflection in geomagnetic variations

International Nuclear Information System (INIS)

Letfus, V.; Apostolov, E.M.

1980-01-01

By analysing the autocorrelation function of the geomagnetic Asup(p)-index, a series of subsidiary maxima were found which seem to indicate that they correspond to periods considerably different from the solar rotation period. It was found that these subsidiary maxima are located symmetrically around the maxima of the first and second recurrences of the solar rotation period (and probably also around the subsequent ones). This fact leads to a model of two or more geoactive longitudes on the Sun. (author)

Dispersed solar thermal generation employing parabolic dish-electric transport with field modulated generator systems

Science.gov (United States)

Ramakumar, R.; Bahrami, K.

1981-01-01

This paper discusses the application of field modulated generator systems (FMGS) to dispersed solar-thermal-electric generation from a parabolic dish field with electric transport. Each solar generation unit is rated at 15 kWe and the power generated by an array of such units is electrically collected for insertion into an existing utility grid. Such an approach appears to be most suitable when the heat engine rotational speeds are high (greater than 6000 r/min) and, in particular, if they are operated in the variable speed mode and if utility-grade a.c. is required for direct insertion into the grid without an intermediate electric energy storage and reconversion system. Predictions of overall efficiencies based on conservative efficiency figures for the FMGS are in the range of 25 per cent and should be encouraging to those involved in the development of cost-effective dispersed solar thermal power systems.

The influence of solar active region evolution on solar wind streams, coronal hole boundaries and geomagnetic storms

Science.gov (United States)

Gold, R. E.; Dodson-Prince, H. W.; Hedeman, E. R.; Roelof, E. C.

1982-01-01

Solar and interplanetary data are examined, taking into account the identification of the heliographic longitudes of the coronal source regions of high speed solar wind (SW) streams by Nolte and Roelof (1973). Nolte and Roelof have 'mapped' the velocities measured near earth back to the sun using the approximation of constant radial velocity. The 'Carrington carpet' for rotations 1597-1616 is shown in a graph. Coronal sources of high speed streams appear in the form of solid black areas. The contours of the stream sources are laid on 'evolutionary charts' of solar active region histories for the Southern and Northern Hemispheres. Questions regarding the interplay of active regions and solar wind are investigated, giving attention to developments during the years 1973, 1974, and 1975.

Retear rate in the late postoperative period after arthroscopic rotator cuff repair.

Science.gov (United States)

Kim, Jae Hwa; Hong, In Tae; Ryu, Keun Jung; Bong, Sun Tae; Lee, Yoon Seok; Kim, Jang Hwan

2014-11-01

Few clinical studies have evaluated the integrity of repaired tendons and identified the timing of retears through the use of serial imaging. Retears after arthroscopic rotator cuff repair are uncommon in the late postoperative period (after 3 months). Case series; Level of evidence, 4. Among 221 arthroscopic rotator cuff repairs that were performed at a single hospital between May 2010 and February 2012, 61 were involved in this study. Rotator cuff tears consisted of 12 small, 31 medium, 8 large, and 6 massive rotator cuff tears. Additionally, 4 isolated subscapularis tears were included. For clinical evaluation, all patients were assessed both preoperatively and postoperatively by use of the University of California-Los Angeles Shoulder Rating Scale, absolute and relative Constant scores, and American Shoulder and Elbow Surgeons score; active range of motion was assessed as well. For radiological evaluation, all 61 patients had a magnetic resonance imaging (MRI) evaluation at 3 months postoperatively. Among them, 23 patients were evaluated for repaired tendon integrity on postoperative MRI at a minimum of 1 year after surgery (mean, 14.1 months; range, 12-19 months), and results were classified according to the Sugaya classification: type I, sufficient thickness with homogeneously low intensity on each image; type II, sufficient thickness, partial high-intensity area; type III, less than half the thickness without discontinuity; type IV, minor discontinuity; and type V, major discontinuity. The remaining 38 patients, who refused to undergo MRI again for financial reasons, were evaluated through ultrasound. Statistically significant clinical improvements were observed after surgery. The MRI conducted at 3 months postoperatively identified 9 patients with Sugaya type I, 28 patients with type II, and 24 patients with type III repairs. No patients showed Sugaya type IV or V repairs at postoperative 3 months. Thirty-seven patients who had shown Sugaya type I or II

Rotational movements of mandibular two-implant overdentures.

Science.gov (United States)

Kimoto, Suguru; Pan, Shaoxia; Drolet, Nicolas; Feine, Jocelyne S

2009-08-01

Clinicians have reported that their patients complain that their mandibular two-implant overdentures (IOD) rotate. Therefore, we studied the frequency and severity of rotation of IODs with two-ball attachments, how rotation may influence perceived satisfaction ratings of chewing ability, and the factors that are involved in the rotation of IODs. Seventy-nine participants were recruited and asked to rate their general satisfaction of their IODs, as well as their ability to chew foods, the existence of any mandibular denture rotation, and to what degree denture rotation bothered them. Data on participant sociodemographic, anatomical, and prosthesis characteristics were also collected. Student's t-test and logistic regression analyses were performed to analyze the differences between participants who did (R group) and did not report (NR group) denture rotation. Thirty-seven of 79 participants were aware of rotational movement in their IODs. These patients were significantly less satisfied with their chewing ability than those who felt no rotation (69.1 mm R group vs. 82.9 mm), and discomfort caused by the rotation bothered them moderately (39/100 mm). The multivariate logistic regression analysis revealed that the arrangement of the anterior teeth and the length of the denture are significantly associated with awareness of denture rotation. Thirty-eight percent in the R group and 31% in the NR group had non-scheduled visits. Rotational movement with a mandibular two-IOD has a negative effect on perceived chewing ability and is associated with anterior tooth arrangement and denture length.

A High Resolution Solar Spectrograph for the Berkeley Undergraduate Astronomy Lab

Science.gov (United States)

Strickler, R.; Bresloff, C.; Graham, J.

2005-05-01

The discovery of extra-solar planets has stimulated interest amongst undergraduates. The Doppler method for detecting exoplanets requires extraction of signals at the 1/1000 of a pixel level. To illustrate this technique, we used a newly built spectrometer to extract sub-pixel Doppler shifts in the solar photosphere. We have used this spectrograph to measure the velocity gradient across the sun and hence infer the solar radius. The limb-to-limb Doppler shift is only 1.8 km/s. A spectral resolution > 100,000 would be required to manifest this motion. Achieving such high spectral resolution is unnecessary since even a small telescope can record high SNR (> 100) spectra. Within a few seconds it is possible to discern solar rotational Doppler shifts at resolutions as low as 10,000. We must also understand coordinate transformation to convert the Doppler signal along the observed diameter to the equatorial rotation speed assuming solid body rotation. The spectrograph system includes an 8-inch Schmidt-Cassegrain stationary telescope; a 100-micron diameter multi-mode fiber; aspheric f-number reformatting optics; a collimating lens; a 110 mm, 80 grooves/mm, θ blaze = 64.5 degree replica echelle grating; and an Apogee 1024 x 1024 thermo-electrically cooled CCD. The spectrometer optics are mounted on a 5-ft x 3-ft optical bench. Operating the spectrometer remotely using VNC and a wireless laptop, we pointed the telescope so that the fiber scanned across a diameter of the solar disk while the CCD took repeated exposures. Although we were "guinea pigs," using the spectrograph for the first time in a class, it worked remarkably well. Combining measurement of the solar radius with observation of the rotation period from sunspots, the earth-sun distance can be deduced. In the future, students may measure the eccentricity of earth's orbit by measuring the sun's radial velocity over the course of a year. This work was supported by the NSF through award DUE-0311536.

Rotating solid foam reactors : mass transfer and reaction rate

NARCIS (Netherlands)

Tschentscher, R.

2012-01-01

In this thesis the performance and applicability of rotating solid foam stirrers is investigated. The stirrer consists, thereby of a solid, highly porous structure, which is used as stirrer and catalyst support simultaneously. The solid foam block occupies a large part of the reactor volume.

THE H α EMISSION OF NEARBY M DWARFS AND ITS RELATION TO STELLAR ROTATION

Energy Technology Data Exchange (ETDEWEB)

Newton, Elisabeth R.; Irwin, Jonathan; Charbonneau, David; Berlind, Perry; Calkins, Michael L.; Mink, Jessica [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2017-01-01

The high-energy emission from low-mass stars is mediated by the magnetic dynamo. Although the mechanisms by which fully convective stars generate large-scale magnetic fields are not well understood, it is clear that, as for solar-type stars, stellar rotation plays a pivotal role. We present 270 new optical spectra of low-mass stars in the Solar Neighborhood. Combining our observations with those from the literature, our sample comprises 2202 measurements or non-detections of H α emission in nearby M dwarfs. This includes 466 with photometric rotation periods. Stars with masses between 0.1 and 0.6 M {sub ⊙} are well-represented in our sample, with fast and slow rotators of all masses. We observe a threshold in the mass–period plane that separates active and inactive M dwarfs. The threshold coincides with the fast-period edge of the slowly rotating population, at approximately the rotation period at which an era of rapid rotational evolution appears to cease. The well-defined active/inactive boundary indicates that H α activity is a useful diagnostic for stellar rotation period, e.g., for target selection for exoplanet surveys, and we present a mass-period relation for inactive M dwarfs. We also find a significant, moderate correlation between L{sub Hα} / L{sub bol} and variability amplitude: more active stars display higher levels of photometric variability. Consistent with previous work, our data show that rapid rotators maintain a saturated value of L{sub Hα} / L {sub bol}. Our data also show a clear power-law decay in L{sub Hα} / L{sub bol} with Rossby number for slow rotators, with an index of −1.7 ± 0.1.

Experimental analysis of flow structure in contra-rotating axial flow pump designed with different rotational speed concept

Science.gov (United States)

Cao, Linlin; Watanabe, Satoshi; Imanishi, Toshiki; Yoshimura, Hiroaki; Furukawa, Akinori

2013-08-01

As a high specific speed pump, the contra-rotating axial flow pump distinguishes itself in a rear rotor rotating in the opposite direction of the front rotor, which remarkably contributes to the energy conversion, the reduction of the pump size, better hydraulic and cavitation performances. However, with two rotors rotating reversely, the significant interaction between blade rows was observed in our prototype contra-rotating rotors, which highly affected the pump performance compared with the conventional axial flow pumps. Consequently, a new type of rear rotor was designed by the rotational speed optimization methodology with some additional considerations, aiming at better cavitation performance, the reduction of blade rows interaction and the secondary flow suppression. The new rear rotor showed a satisfactory performance at the design flow rate but an unfavorable positive slope of the head — flow rate curve in the partial flow rate range less than 40% of the design flow rate, which should be avoided for the reliability of pump-pipe systems. In the present research, to understand the internal flow field of new rear rotor and its relation to the performances at the partial flow rates, the velocity distributions at the inlets and outlets of the rotors are firstly investigated. Then, the boundary layer flows on rotor surfaces, which clearly reflect the secondary flow inside the rotors, are analyzed through the limiting streamline observations using the multi-color oil-film method. Finally, the unsteady numerical simulations are carried out to understand the complicated internal flow structures in the rotors.

Vertical profiles of aerosol optical properties and the solar heating rate estimated by combining sky radiometer and lidar measurements

Science.gov (United States)

Kudo, Rei; Nishizawa, Tomoaki; Aoyagi, Toshinori

2016-07-01

The SKYLIDAR algorithm was developed to estimate vertical profiles of aerosol optical properties from sky radiometer (SKYNET) and lidar (AD-Net) measurements. The solar heating rate was also estimated from the SKYLIDAR retrievals. The algorithm consists of two retrieval steps: (1) columnar properties are retrieved from the sky radiometer measurements and the vertically mean depolarization ratio obtained from the lidar measurements and (2) vertical profiles are retrieved from the lidar measurements and the results of the first step. The derived parameters are the vertical profiles of the size distribution, refractive index (real and imaginary parts), extinction coefficient, single-scattering albedo, and asymmetry factor. Sensitivity tests were conducted by applying the SKYLIDAR algorithm to the simulated sky radiometer and lidar data for vertical profiles of three different aerosols, continental average, transported dust, and pollution aerosols. The vertical profiles of the size distribution, extinction coefficient, and asymmetry factor were well estimated in all cases. The vertical profiles of the refractive index and single-scattering albedo of transported dust, but not those of transported pollution aerosol, were well estimated. To demonstrate the performance and validity of the SKYLIDAR algorithm, we applied the SKYLIDAR algorithm to the actual measurements at Tsukuba, Japan. The detailed vertical structures of the aerosol optical properties and solar heating rate of transported dust and smoke were investigated. Examination of the relationship between the solar heating rate and the aerosol optical properties showed that the vertical profile of the asymmetry factor played an important role in creating vertical variation in the solar heating rate. We then compared the columnar optical properties retrieved with the SKYLIDAR algorithm to those produced with the more established scheme SKYRAD.PACK, and the surface solar irradiance calculated from the SKYLIDAR

Solar ultraviolet radiation induced variations in the stratosphere and mesosphere

Science.gov (United States)

Hood, L. L.

1987-01-01

The detectability and interpretation of short-term solar UV induced responses of middle atmospheric ozone, temperature, and dynamics are reviewed. The detectability of solar UV induced perturbations in the middle atmosphere is studied in terms of seasonal and endogenic dynamical variations. The interpretation of low-latitude ozone and possible temperature responses on the solar rotation time scale is examined. The use of these data to constrain or test photochemical model predictions is discussed.

High-latitude Conic Current Sheets in the Solar Wind

Energy Technology Data Exchange (ETDEWEB)

Khabarova, Olga V.; Obridko, Vladimir N.; Kharshiladze, Alexander F. [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN), Moscow (Russian Federation); Malova, Helmi V. [Scobeltsyn Nuclear Physics Institute of Lomonosov Moscow State University, Moscow (Russian Federation); Kislov, Roman A.; Zelenyi, Lev M. [Space Research Centre of the Polish Academy of Sciences (CBK PAN), Warsaw (Poland); Tokumaru, Munetoshi; Fujiki, Ken’ichi [Institute for Space-Earth Environmental Research, Nagoya University (Japan); Sokół, Justyna M.; Grzedzielski, Stan [Space Research Centre of the Polish Academy of Sciences (CBK), Warsaw (Poland)

2017-02-10

We provide observational evidence for the existence of large-scale cylindrical (or conic-like) current sheets (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2–3 au several times in 1994, as the CCS was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of conic-like magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/ nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk–Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers.

Physics of Rotating and Expanding Black Hole Universe

Directory of Open Access Journals (Sweden)

Seshavatharam U. V. S.

2010-04-01

Full Text Available Throughout its journey universe follows strong gravity. By unifying general theory of relativity and quantum mechanics a simple derivation is given for rotating black hole's temperature. It is shown that when the rotation speed approaches light speed temperature approaches Hawking's black hole temperature. Applying this idea to the cosmic black hole it is noticed that there is "no cosmic temperature" if there is "no cosmic rotation". Starting from the Planck scale it is assumed that universe is a rotating and expanding black hole. Another key assumption is that at any time cosmic black hole rotates with light speed. For this cosmic sphere as a whole while in light speed rotation "rate of decrease" in temperature or "rate of increase" in cosmic red shift is a measure of "rate of cosmic expansion". Since 1992, measured CMBR data indicates that, present CMB is same in all directions equal to $2.726^circ$ K, smooth to 1 part in 100,000 and there is no continuous decrease! This directly indicates that, at present rate of decrease in temperature is practically zero and rate of expansion is practically zero. Universe is isotropic and hence static and is rotating as a rigid sphere with light speed. At present galaxies are revolving with speeds proportional to their distances from the cosmic axis of rotation. If present CMBR temperature is $2.726^circ$ K, present value of obtained angular velocity is $2.17 imes 10^{-18}$ rad/sec $cong$ 67 Km/sec$imes$Mpc. Present cosmic mass density and cosmic time are fitted with a $ln (volume ratio$ parameter. Finally it can be suggested that dark matter and dark energy are ad-hoc and misleading concepts.

Evolution of rotating stars. III. Predicted surface rotation velocities for stars which conserve total angular momentum

International Nuclear Information System (INIS)

Endal, A.S.; Sofia, S.

1979-01-01

Predicted surface rotation velocities are presented for Population I stars at 10, 7, 5, 3, and 1.5M/sub sun/. The surface velocities have been computed for three different cases of angular momentum redistribution: no radial redistribution (rotation on decoupled shells), complete redistribution (rigid-body rotation), and partial redistribution as predicted by detailed consideration of circulation currents in rotation stars. The velocities for these cases are compared to each other and to observed stellar rotation rates (upsilon sin i).Near the main sequence, rotational effects can substantially reduce the moment of inertia of a star, so nonrotating models consistently underestimate the expected velocities for evolving stars. The magnitude of these effects is sufficient to explain the large numbers of Be stars and, perhaps, to explain the bimodal distribution of velocities observed for the O stars.On the red giant branch, angular momentum redistribution reduces the surface velocity by a factor of 2 or more, relative to the velocity expected for no radial redistribution. This removes the discrepancy between predicted and observed rotation rates for the K giants and makes it unlikely that these stars lose significant amounts of angular momentum by stellar winds. Our calculations indicate that improved observations (by the Fourier-transform technique) of the red giants in the Hyades cluster can be used to determine how angular momentum is redistributed by convection

Temporal flow instability for Magnus-Robins effect at high rotation rates

Science.gov (United States)

Sengupta, T. K.; Kasliwal, A.; de, S.; Nair, M.

2003-06-01

The lift and drag coefficients of a circular cylinder, translating and spinning at a supercritical rate is studied theoretically to explain the experimentally observed violation of maximum mean lift coefficient principle, that was proposed heuristically by Prandtl on the basis of inviscid flow model. It is also noted experimentally that flow past a rotating and translating cylinder experiences temporal instability-a fact not corroborated by any theoretical studies so far. In the present paper we report very accurate solution of Navier-Stokes equation that displays the above-mentioned instability and the violation of the maximum limit. The calculated lift coefficient exceeds the limit of /4π, instantaneously as well as in time-averaged sense. The main purpose of the present paper is to explain the observed temporal instability sequence in terms of a new theory of instability based on full Navier-Stokes equation that does not require making any assumption about the flow field, unlike other stability theories.

The amplitude of the deep solar convection and the origin of the solar supergranulation

Science.gov (United States)

Rast, Mark

2017-11-01

Recent observations and models have raised questions about our understanding of the dynamics of the deep solar convection. In particular, the amplitude of low wavenumber convective motions appears to be too high in both local area radiative magnetohydrodynamic and global spherical shell magnetohydrodynamic simulations. In global simulations this results in weaker than needed rotational constraints and consequent non solar-like differential rotation profiles. In deep local area simulations it yields strong horizontal flows in the photosphere on scales much larger than the observed supergranulation. We have undertaken numerical studies that suggest that solution to this problem is closely related to the long standing question of the origin of the solar supergranulation. Two possibilities have emerged. One suggests that small scale photospherically driven motions dominate convecive transport even at depth, descending through a very nearly adiabatic interior (more more nearly adiabatic than current convection models achieve). Convection of this form can meet Rossby number constraints set by global scale motions and implies that the solar supergranulation is the largest buoyantly driven scale of motion in the Sun. The other possibility is that large scale convection driven deeep in the Sun dynamically couples to the near surface shear layer, perhaps as its origin. In this case supergranulation would be the largest non-coupled convective mode, or only weakly coupled and thus potentially explaining the observed excess power in the prograde direction. Recent helioseismic results lend some support to this. We examind both of these possibilities using carefully designed numerical experiments, and weigh thier plausibilities in light of recent observations.

Differential Rotation in Sun-like Stars from Surface Variability and Asteroseismology

Science.gov (United States)

Nielsen, Martin Bo

2017-03-01

The Sun and other stars are known to oscillate. Through the study of small perturbations to the frequencies of these oscillations the rotation of the deep interior can be inferred. However, thus far the internal rotation of other Sun-like stars is unknown. The NASA Kepler mission has observed a multitude of Sun-like stars over a period of four years. This has provided high-quality photometric data that can be used to study the rotation of stars with two different techniques: asteroseismology and surface activity. Asteroseismology provides a means of measuring rotation in the stellar interior, while photometric variability from magnetically active regions are sensitive to rotation at the stellar surface. The combination of these two methods can be used to constrain the radial differential rotation in Sun-like stars. First, we developed an automated method for measuring the rotation of stars using surface variability. This method was initially applied to the entire Kepler catalog, out of which we detected signatures of rotation in 12,000 stars across the main sequence, providing robust estimates of the surface rotation rates and the associated errors. Second, we performed an asteroseismic analysis of six Sun-like stars, where we were able to measure the rotational splitting as a function of frequency in the p-mode envelope. This was done by dividing the oscillation spectrum into individual segments, and fitting a model independently to each segment. We found that the measured splittings were all consistent with a constant value, indicating little differential rotation. Third, we compared the asteroseismic rotation rates of five Sun-like stars to their surface rotation rates. We found that the values were in good agreement, again indicating little differential rotation between the regions where the two methods are most sensitive. Finally, we discuss how the surface rotation rates may be used as a prior on the seismic envelope rotation rate in a double-zone model

Variations of Solar Non-axisymmetric Activity

Science.gov (United States)

Gyenge, N.; Baranyi, T.; Ludmány, A.

The temporal behaviour of solar active longitudes has been examined by using two sunspot catalogues, the Greenwich Photoheliographic Results (GPR) and the Debrecen Photoheliographic Data (DPD). The time-longitude diagrams of the activity distribution reveal the preferred longitudinal zones and their migration with respect to the Carrington frame. The migration paths outline a set of patterns in which the activity zone has alternating prograde/retrograde angular velocities with respect to the Carrington rotation rate. The time profiles of these variations can be described by a set of successive parabolae. Two similar migration paths have been selected from these datasets, one northern path during cycles 21 - 22 and one southern path during cycles 13 - 14, for closer examination and comparison of their dynamical behaviours. The rates of sunspot emergence exhibited in both migration paths similar periodicities, close to 1.3 years. This behaviour may imply that the active longitude is connected to the bottom of convection zone.

Rotational instabilities in field reversed configurations

International Nuclear Information System (INIS)

Santiago, M.A.M.; Tsui, K.H.; Ponciano, B.M.B.; Sakanaka, P.H.

1988-01-01

The rotational instability (n = 2 toroidal mode) in field reversed configurations (FRC) using the ideal MHD equations in cylindrical geometry is studied. These equations are solved using a realistic densite profile, and the influence of some plasma parameters on the growth rate is analysed. The model shows good qualitative results. The growth rate increases rapidly as rotational frequency goes up and the mode m = 2 dominates over the m = 1 mode. With the variation of the density profile, it is observed that the growth rate decreases as the density dip at the center fills up. Calculated value ranges from 1/2 to 1/7 of the rotational frequency Ω whereas the measured value is around Ω/50. The developed analysis is valid for larger machines. The influence of the plasma resistivity on the mode stabilization is also analysed. The resistivity, which is the fundamental factor in the formation of compact torus, tends to decrease the growth rate. (author) [pt

Solar pulsations

International Nuclear Information System (INIS)

Zirker, J.B.

1980-01-01

Oscillations of the surface of the sun, with periods between 5 and 160 min, have been observed by several spectroscopic techniques, and preliminary interpretations have been offered. The 5-min oscillations are global, nonradial, acoustic standing waves in the subsurface zone. Internal differential rotation speeds have been deduced from the Doppler splitting of these waves. Oscillations with longer periods have been reported, but need confirmation. The longest periods offer a tool for investigating the solar interior

A model of the solar cycle driven by the dynamo action of the global convection in the solar convection zone

International Nuclear Information System (INIS)

Yoshimura, H.

1975-01-01

The dynamo equation which represents the longitudinally averaged magnetohydrodynamical action of the global convection influenced by the rotation in the solar convection zone is solved numerically to simulate the solar cycle as an initial boundary-value problem. The radial and latitudinal structure of the dynamo action is parametrized in accordance with the structure of the rotation, and of the global convection especially in such a way as to represent the presence of the two cells of the regeneration action in the radial direction in which the action has opposite signs, which is typical of the regeneration action of the global convection. A nonlinear process is included by assuming that part of the magnetic field energy is dissipated when the magnetic field strength exceeds some critical value; the formation of active regions and subsequent dissipations are thus simulated. By adjusting the parameters within a reasonable range, oscillatory solutions are obtained to simulate the solar cycle with the period of the right order of magnitude and with the patterns of evolution of the latitudinal distribution of the toroidal component of the magnetic field similar to the observed Butterfly Diagram of sunspots. The evolution of the latitudinal distribution of the radial component of the magnetic field shows patterns similar to the Butterfly Diagram, but having two branches of different polarity in each hemisphere. The development of the radial structure of the magnetic field associated with the solar cycle is presented. The importance of the poleward migrating branch of the Butterfly Diagram is emphasized in relation to the relative importance of the role of the latitudinal and radial shears of the differential rotation

The role of helioseismology in the knowledge of the solar interior dynamics and in the solar neutrino puzzle

International Nuclear Information System (INIS)

Couvidat, Sebastien

2002-01-01

This dissertation focuses on the solar interior dynamics and the neutrino puzzle, using helioseismology and more specifically the SoHO/GOLF data as a tool to probe the radiative interior of the Sun. We show how helioseismology gives us a direct access to the deep-layer dynamics through the solar rotation profile. Our data favor a decrease of the rotation velocity near the nuclear core. This can be used to constrain the angular momentum distribution processes, and to set an upper bound on the intensity of the magnetic field in this part of the Sun. The search for gravity modes with an original method is another topic of this dissertation. Several candidates are detected that need now to be confirmed. Gravity modes will give us a precious insight into the solar core structure and dynamics. We also use the stellar evolution code CESAM. By combining seismic data and solar modelling, we produce solar seismic models. The neutrino flux predictions from these models are partly derived on an observational basis. The comparison of these fluxes with the SNO results gives the solution to the solar neutrino puzzle: neutrinos have masses and they oscillate between different lepton flavors. This explains the deficit of detections observed since the sixties. We also work on the internal magnetic fields that take part to the dynamic processes. In particular, we start to study the impact of these fields on the neutrino production and transport. Finally, we reach the limits of the 1D stellar codes: they cannot take into account the dynamic processes efficiently. This justifies the current development of 2D or 3D codes. (author) [fr

MODELING THE VARIATIONS OF DOSE RATE MEASURED BY RAD DURING THE FIRST MSL MARTIAN YEAR: 2012–2014

Energy Technology Data Exchange (ETDEWEB)

Guo, Jingnan; Wimmer-Schweingruber, Robert F.; Heber, Bernd; Köhler, Jan; Appel, Jan K.; Böhm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Lohf, Henning; Martin, Cesar [Institute of Experimental and Applied Physics, Christian-Albrechts-University, Kiel (Germany); Zeitlin, Cary [Southwest Research Institute, Earth, Oceans and Space Department, Durham, NH (United States); Rafkin, Scot; Hassler, Donald M.; Ehresmann, Bent [Southwest Research Institute, Space Science and Engineering Division, Boulder, CO (United States); Posner, Arik [NASA Headquarters, Science Mission Directorate, Washington, DC (United States); Brinza, David E. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States); Kahanpää, H. [Finnish Meteorological Institute, Helsinki (Finland); Reitz, Günther, E-mail: guo@physik.uni-kiel.de [Aerospace Medicine, Deutsches Zentrum für Luft- und Raumfahrt, Köln (Germany)

2015-09-01

The Radiation Assessment Detector (RAD), on board Mars Science Laboratory’s (MSL) rover Curiosity, measures the energy spectra of both energetic charged and neutral particles along with the radiation dose rate at the surface of Mars. With these first-ever measurements on the Martian surface, RAD observed several effects influencing the galactic cosmic-ray (GCR) induced surface radiation dose concurrently: (a) short-term diurnal variations of the Martian atmospheric pressure caused by daily thermal tides, (b) long-term seasonal pressure changes in the Martian atmosphere, and (c) the modulation of the primary GCR flux by the heliospheric magnetic field, which correlates with long-term solar activity and the rotation of the Sun. The RAD surface dose measurements, along with the surface pressure data and the solar modulation factor, are analyzed and fitted to empirical models that quantitatively demonstrate how the long-term influences ((b) and (c)) are related to the measured dose rates. Correspondingly, we can estimate dose rate and dose equivalents under different solar modulations and different atmospheric conditions, thus allowing empirical predictions of the Martian surface radiation environment.

Preparation of Ga-doped ZnO films by pulsed dc magnetron sputtering with cylindrical rotating target for thin film solar cell applications

International Nuclear Information System (INIS)

Shin, Beom-Ki; Lee, Tae-Il; Park, Ji-Hyeon; Park, Kang-Il; Ahn, Kyung-Jun; Park, Sung-Kee; Lee, Woong; Myoung, Jae-Min

2011-01-01

Applicability of Ga-doped ZnO (GZO) films for thin film solar cells (TFSCs) was investigated by preparing GZO films via pulsed dc magnetron sputtering (PDMS) with rotating target. The GZO films showed improved crystallinity and increasing degree of Ga doping with increasing thickness to a limit of 1000 nm. The films also fulfilled requirements for the transparent electrodes of TFSCs in terms of electrical and optical properties. Moreover, the films exhibited good texturing potential based on etching studies with diluted HCl, which yielded an improved light trapping capability without significant degradation in electrical propreties. It is therefore suggested that the surface-textured GZO films prepared via PDMS and etching are promising candidates for indium-free transparent electrodes for TFSCs.

Preparation of Ga-doped ZnO films by pulsed dc magnetron sputtering with cylindrical rotating target for thin film solar cell applications

Science.gov (United States)

Shin, Beom-Ki; Lee, Tae-Il; Park, Ji-Hyeon; Park, Kang-Il; Ahn, Kyung-Jun; Park, Sung-Kee; Lee, Woong; Myoung, Jae-Min

2011-11-01

Applicability of Ga-doped ZnO (GZO) films for thin film solar cells (TFSCs) was investigated by preparing GZO films via pulsed dc magnetron sputtering (PDMS) with rotating target. The GZO films showed improved crystallinity and increasing degree of Ga doping with increasing thickness to a limit of 1000 nm. The films also fulfilled requirements for the transparent electrodes of TFSCs in terms of electrical and optical properties. Moreover, the films exhibited good texturing potential based on etching studies with diluted HCl, which yielded an improved light trapping capability without significant degradation in electrical propreties. It is therefore suggested that the surface-textured GZO films prepared via PDMS and etching are promising candidates for indium-free transparent electrodes for TFSCs.

Solar ultraviolet-B radiation affects seedling emergence, DNA integrity, plant morphology, growth rate, and attractiveness to herbivore insects in Datura ferox

International Nuclear Information System (INIS)

Ballare, C.L.; Scopel, A.L.; Stapleton, A.E.

1996-01-01

To study functional relationships between the effects of solar ultraviolet-B radiation (UV0B) on different aspects of the physiology of a wild plant, we carried out exclusion experiments in the field with the summer annual Datura ferrox L. Solar UV-B incident over Buenos Aires reduced daytime seedling emergence, inhibited stem elongation and leaf expansion, and tended to reduce biomass accumulation during early growth. However, UV-B had no effect on calculated net assimilation rate. Using a monoclonal antibody specific to the cyclobutane-pyrimidine dimer (CPD), we found that plants receiving full sunlight had more CPDs per unit of DNA than plants shielded from solar UV-B, but the positive correlation between UV-B and CPD burden tended to level off at high (near solar) UV-B levels. At our field site, Datura plants were consumed by leaf beetles (Coleoptera), and the proportion of plants attacked by insects declined with the amount of UV-B received during growth. Field experiments showed that plant exposure to solar UV-B reduced the likelihood of leaf beetle attack by one-half. Our results highlight the complexities associated with scaling plant responses to solar UV-B, because they show: (a) a lack of correspondence between UV-B effects on net assimilation rate and whole-plant growth rate, (b) nonlinear UV-B dose-response curves, and (c) UV-B effects of plant attractiveness to natural herbivores. 56 refs., 7 figs

Physics of Rotating and Expanding Black Hole Universe

Directory of Open Access Journals (Sweden)

Seshavatharam U. V. S.

2010-04-01

Full Text Available Throughout its journey universe follows strong gravity. By unifying general theory of relativity and quantum mechanics a simple derivation is given for rotating black hole’s temperature. It is shown that when the rotation speed approaches light speed temperature approaches Hawking’s black hole temperature. Applying this idea to the cosmic black hole it is noticed that there is “no cosmic temperature” if there is “no cosmic rotation”. Starting from the Planck scale it is assumed that- universe is a rotating and expanding black hole. Another key assumption is that at any time cosmic black hole rotates with light speed. For this cosmic sphere as a whole while in light speed rotation “rate of decrease” in temperature or “rate of increase” in cosmic red shift is a measure of “rate of cosmic expansion”. Since 1992, measured CMBR data indicates that, present CMB is same in all directions equal to 2 : 726 K ; smooth to 1 part in 100,000 and there is no continuous decrease! This directly indicates that, at present rate of decrease in temperature is practically zero and rate of expansion is practically zero. Universe is isotropic and hence static and is rotating as a rigid sphere with light speed. At present galaxies are revolving with speeds proportional to their distances from the cosmic axis of rotation. If present CMBR temperature is 2 : 726 K, present value of obtained angular velocity is 2 : 17 10 Present cosmic mass density and cosmic time are fitted with a ln ( volume ratio parameter. Finally it can be suggested that dark matter and dark energy are ad-hoc and misleading concepts.

A novel adaptive sun tracker for spacecraft solar panel based on hybrid unsymmetric composite laminates

Science.gov (United States)

Wu, Zhangming; Li, Hao

2017-11-01

This paper proposes a novel adaptive sun tracker which is constructed by hybrid unsymmetric composite laminates. The adaptive sun tracker could be applied on spacecraft solar panels to increase their energy efficiency through decreasing the inclined angle between the sunlight and the solar panel normal. The sun tracker possesses a large rotation freedom and its rotation angle depends on the laminate temperature, which is affected by the light condition in the orbit. Both analytical model and finite element model (FEM) are developed for the sun tracker to predict its rotation angle in different light conditions. In this work, the light condition of the geosynchronous orbit on winter solstice is considered in the numerical prediction of the temperatures of the hybrid laminates. The final inclined angle between the sunlight and the solar panel normal during a solar day is computed using the finite element model. Parametric study of the adaptive sun tracker is conducted to improve its capacity and effectiveness of sun tracking. The improved adaptive sun tracker is lightweight and has a state-of-the-art design. In addition, the adaptive sun tracker does not consume any power of the solar panel, since it has no electrical driving devices. The proposed adaptive sun tracker provides a potential alternative to replace the traditional sophisticated electrical driving mechanisms for spacecraft solar panels.

An algorithm to evaluate solar irradiance and effective dose rates using spectral UV irradiance at four selected wavelengths

International Nuclear Information System (INIS)

Anav, A.; Rafanelli, C.; Di Menno, I.; Di Menno, M.

2004-01-01

The paper shows a semi-analytical method for environmental and dosimetric applications to evaluate, in clear sky conditions, the solar irradiance and the effective dose rates for some action spectra using only four spectral irradiance values at selected wavelengths in the UV-B and UV-A regions (305, 320, 340 and 380 nm). The method, named WL4UV, is based on the reconstruction of an approximated spectral irradiance that can be integrated, to obtain the solar irradiance, or convoluted with an action spectrum to obtain an effective dose rate. The parameters required in the algorithm are deduced from archived solar spectral irradiance data. This database contains measurements carried out by some Brewer spectrophotometers located in various geographical positions, at similar altitudes, with very different environmental characteristics: Rome (Italy), Ny Aalesund (Svalbard Islands (Norway)) and Ushuaia (Tierra del Fuego (Argentina)). To evaluate the precision of the method, a double test was performed with data not used in developing the model. Archived Brewer measurement data, in clear sky conditions, from Rome and from the National Science Foundation UV data set in San Diego (CA, USA) and Ushuaia, where SUV 100 spectro-radiometers operate, were drawn randomly. The comparison of measured and computed irradiance has a relative deviation of about ±2%. The effective dose rates for action spectra of Erythema, DNA and non-Melanoma skin cancer have a relative deviation of less than ∼20% for solar zenith angles <50 deg.. (authors)

Energy rating of solar modules; Workshop 'vergleichender Modulertrag'

Energy Technology Data Exchange (ETDEWEB)

Kroeni, R. (ed.)

2002-07-01

This final report for the Swiss Federal Office of Energy presents the results of a workshop held in Zurich, Switzerland. The project aimed to help commercial investors in the photovoltaics area who need better information on component costs involved in photovoltaics installations. Today, solar module prices are compared using the power output under standard conditions. The authors propose that they should be compared with their energy production. The workshop, held in March 2002 in Zurich, aimed to provide an overview of existing rating methods for energy production. Various methods of comparison are discussed, including a matrix method based on electrical and meteorological measurements, a production calculation method involving efficiency measurements made for various locations and conditions as well as another approach that takes irradiance, cell temperature, spectral correction into account. A further method of calculating energy ratings from laboratory measurements is also presented, as is a review of developments in relevant standardisation areas. Various methods are compared and commented on.

Identification of new solar OH lines in the 10--12 micron region

International Nuclear Information System (INIS)

Goldman, A.; Murcray, F.J.; Gillis, J.R.; Murcray, D.G.

1981-01-01

High-resolution (0.02 cm -1 ) infrared solar spectra obtained with a balloon-borne interferometer reveal new solar absorption features, which appear as regularly spaced quartets, in the 825--960 cm -1 region. The lines are interpreted as high N'' (25--33) pure rotation lines of solar OH. An effective amount of approx.8 x 10 15 molecules cm -2 of OH is estimated from the spectra

SOLAR MAGNETIZED 'TORNADOES': RELATION TO FILAMENTS

Energy Technology Data Exchange (ETDEWEB)

Su Yang; Veronig, Astrid; Temmer, Manuela [IGAM-Kanzelhoehe Observatory, Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Wang Tongjiang [Department of Physics, Catholic University of America, Washington, DC 20064 (United States); Gan Weiqun, E-mail: yang.su@uni-graz.at [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2012-09-10

Solar magnetized 'tornadoes', a phenomenon discovered in the solar atmosphere, appear as tornado-like structures in the corona but are rooted in the photosphere. Like other solar phenomena, solar tornadoes are a feature of magnetized plasma and therefore differ distinctly from terrestrial tornadoes. Here we report the first analysis of solar 'tornadoes' (two papers which focused on different aspects of solar tornadoes were published in the Astrophysical Journal Letters and Nature, respectively, during the revision of this Letter). A detailed case study of two events indicates that they are rotating vertical magnetic structures probably driven by underlying vortex flows in the photosphere. They usually exist as a group and are related to filaments/prominences, another important solar phenomenon whose formation and eruption are still mysteries. Solar tornadoes may play a distinct role in the supply of mass and twists to filaments. These findings could lead to a new explanation of filament formation and eruption.

Improved thermodynamics of the dense solar plasma and molecular-dynamics simulations of the nuclear-reaction rates

Science.gov (United States)

Mao, Dan

The conditions in the solar interior are so extreme that it has so far been impossible to match them in a laboratory. However, for nearly 50 years solar oscillations have been precisely observed, and the wealth of their data has enabled us to study the interior of the Sun as if it were a laboratory. Helioseismology is the name of this branch of astrophysics. It allows a high- precision diagnostic of the thermodynamic quantities in the solar interior. High-quality thermodynamic quantities are crucial for successful solar modeling. If good solar models are desired, considerable theoretical effort is required. Good solar models, in turn, are fundamental tools for solar physics. The most prominent example of this link between solar physics and basic physics was the resolution of the solar neutrino problem in 2002. The equation of state is a key material property that describes the relation between pressure, density and temperature. If the equation of state is derived from a thermodynamic potential it will also determine all associated thermodynamic quantities. A second key material property is the nuclear-energy production rate, which plays a crucial role in the solar core. Both are important physical properties describing the structure of the Sun. Both derive from microphysical models. In the equation-of-state part, we have studied two models of the equation of state (EOS). One is the MHD EOS, which is widely used in solar models. In our research, we have incorporated new terms into the MHD EOS. These terms have been borrowed from the major competing formalism, the OPAL EOS. They were missing in the original MHD EOS. Not only do the upgrades bring MHD closer to the OPAL equation of state, which is well known for its better match with observations. Most importantly it will allow solar modelers to use the OPAL equation of state directly, without recourse to the OPAL tables distributed by the Lawrence Livermore National Laboratory. Since the OPAL code is not publicly

Tomographic Validation of the AWSoM Model of the Inner Corona During Solar Minima

Science.gov (United States)

Manchester, W.; Vásquez, A. M.; Lloveras, D. G.; Mac Cormack, C.; Nuevo, F.; Lopez-Fuentes, M.; Frazin, R. A.; van der Holst, B.; Landi, E.; Gombosi, T. I.

2017-12-01

Continuous improvement of MHD three-dimensional (3D) models of the global solar corona, such as the Alfven Wave Solar Model (AWSoM) of the Space Weather Modeling Framework (SWMF), requires testing their ability to reproduce observational constraints at a global scale. To that end, solar rotational tomography based on EUV image time-series can be used to reconstruct the 3D distribution of the electron density and temperature in the inner solar corona (r used to validate steady-state 3D MHD simulations of the inner corona using the latest version of the AWSoM model. We perform the study for selected rotations representative of solar minimum conditions, when the global structure of the corona is more axisymmetric. We analyse in particular the ability of the MHD simulation to match the tomographic results across the boundary region between the equatorial streamer belt and the surrounding coronal holes. The region is of particular interest as the plasma flow from that zone is thought to be related to the origin of the slow component of the solar wind.

Units of rotational information

Science.gov (United States)

Yang, Yuxiang; Chiribella, Giulio; Hu, Qinheping

2017-12-01

Entanglement in angular momentum degrees of freedom is a precious resource for quantum metrology and control. Here we study the conversions of this resource, focusing on Bell pairs of spin-J particles, where one particle is used to probe unknown rotations and the other particle is used as reference. When a large number of pairs are given, we show that every rotated spin-J Bell state can be reversibly converted into an equivalent number of rotated spin one-half Bell states, at a rate determined by the quantum Fisher information. This result provides the foundation for the definition of an elementary unit of information about rotations in space, which we call the Cartesian refbit. In the finite copy scenario, we design machines that approximately break down Bell states of higher spins into Cartesian refbits, as well as machines that approximately implement the inverse process. In addition, we establish a quantitative link between the conversion of Bell states and the simulation of unitary gates, showing that the fidelity of probabilistic state conversion provides upper and lower bounds on the fidelity of deterministic gate simulation. The result holds not only for rotation gates, but also to all sets of gates that form finite-dimensional representations of compact groups. For rotation gates, we show how rotations on a system of given spin can simulate rotations on a system of different spin.

On the measurements of large scale solar velocity fields

International Nuclear Information System (INIS)

Andersen, B.N.

1985-01-01

A general mathematical formulation for the correction of the scattered light influence on solar Doppler shift measurements has been developed. This method has been applied to the straylight correction of measurements of solar rotation, limb effect, large scale flows and oscillations. It is shown that neglecting the straylight errors may cause spurious large scale velocity fields, oscillations and erronous values for the solar rotation and limb effect. The influence of active regions on full disc velocity measurements has been studied. It is shown that a 13 day periodicity in the global velocity signal will be introduced by the passage of sunspots over the solar disc. With different types of low resolution apertures, other periodicities may be introduced. Accurate measurements of the center-to-limb velocity shift are presented for a set of magnetic insensitive lines well suited for solar velocity measurements. The absolute wavelenght shifts are briefly discussed. The stronger lines have a ''supergravitational'' shift of 300-400 m/s at the solar limb. The results may be explained by the presence of a 20-25 m/s poleward meridional flow and a latitudinal dependence of the granular parameters. Using a simple model it is shown that the main properites of the observations are explained by a 5% increase in the granular size with latitude. Data presented indicate that the resonance line K I, 769.9 nm has a small but significant limb effect of 125 m/s from center to limb

The rotation of Titan and Ganymede

Science.gov (United States)

Van Hoolst, Tim; Coyette, Alexis; Baland, Rose-Marie; Trinh, Antony

2016-10-01

The rotation rates of Titan and Ganymede, the largest satellites of Saturn and Jupiter, are on average equal to their orbital mean motion. Here we discuss small deviations from the average rotation for both satellites and evaluate the polar motion of Titan induced by its surface fluid layers. We examine different causes at various time scales and assess possible consequences and the potential of using librations and polar motion as probes of the interior structure of the satellites.The rotation rate of Titan and Ganymede cannot be constant on the orbital time scale as a result of the gravitational torque of the central planet acting on the satellites. Titan is moreover expected to show significant polar motion and additional variations in the rotation rate due to angular momentum exchange with the atmosphere, mainly at seasonal periods. Observational evidence for deviations from the synchronous state has been reported several times for Titan but is unfortunately inconclusive. The measurements of the rotation variations are based on determinations of the shift in position of Cassini radar images taken during different flybys. The ESA JUICE (JUpiter ICy moons Explorer) mission will measure the rotation variations of Ganymede during its orbital phase around the satellite starting in 2032.We report on different theoretical aspects of the librations and polar motion. We consider the influence of the rheology of the ice shell and take into account Cassini measurements of the external gravitational field and of the topography of Titan and similar Galileo data about Ganymede. We also evaluate the librations and polar motion induced by Titan's hydrocarbon seas and use the most recent results of Titan's atmosphere dynamics. We finally evaluate the potential of rotation variations to constrain the satellite's interior structure, in particular its ice shell and ocean.

Impact of Rate Design Alternatives on Residential Solar Customer Bills. Increased Fixed Charges, Minimum Bills and Demand-based Rates

Energy Technology Data Exchange (ETDEWEB)

Bird, Lori [National Renewable Energy Lab. (NREL), Golden, CO (United States); Davidson, Carolyn [National Renewable Energy Lab. (NREL), Golden, CO (United States); McLaren, Joyce [National Renewable Energy Lab. (NREL), Golden, CO (United States); Miller, John [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2015-09-01

With rapid growth in energy efficiency and distributed generation, electric utilities are anticipating stagnant or decreasing electricity sales, particularly in the residential sector. Utilities are increasingly considering alternative rates structures that are designed to recover fixed costs from residential solar photovoltaic (PV) customers with low net electricity consumption. Proposed structures have included fixed charge increases, minimum bills, and increasingly, demand rates - for net metered customers and all customers. This study examines the electricity bill implications of various residential rate alternatives for multiple locations within the United States. For the locations analyzed, the results suggest that residential PV customers offset, on average, between 60% and 99% of their annual load. However, roughly 65% of a typical customer's electricity demand is non-coincidental with PV generation, so the typical PV customer is generally highly reliant on the grid for pooling services.

Developing an Asteroid Rotational Theory

Science.gov (United States)

Geis, Gena; Williams, Miguel; Linder, Tyler; Pakey, Donald

2018-01-01

The goal of this project is to develop a theoretical asteroid rotational theory from first principles. Starting at first principles provides a firm foundation for computer simulations which can be used to analyze multiple variables at once such as size, rotation period, tensile strength, and density. The initial theory will be presented along with early models of applying the theory to the asteroid population. Early results confirm previous work by Pravec et al. (2002) that show the majority of the asteroids larger than 200m have negligible tensile strength and have spin rates close to their critical breakup point. Additionally, results show that an object with zero tensile strength has a maximum rotational rate determined by the object’s density, not size. Therefore, an iron asteroid with a density of 8000 kg/m^3 would have a minimum spin period of 1.16h if the only forces were gravitational and centrifugal. The short-term goal is to include material forces in the simulations to determine what tensile strength will allow the high spin rates of asteroids smaller than 150m.

Escape trajectories of solar sails and general relativity

Energy Technology Data Exchange (ETDEWEB)

Kezerashvili, Roman Ya. [Physics Department, New York City College of Technology, City University of New York, 300 Jay Street, Brooklyn, NY 11201 (United States); Graduate School and University Center, City University of New York, 365 Fifth Avenue, New York, NY 10016 (United States); Vazquez-Poritz, Justin F., E-mail: jvazquez-poritz@citytech.cuny.ed [Physics Department, New York City College of Technology, City University of New York, 300 Jay Street, Brooklyn, NY 11201 (United States); Graduate School and University Center, City University of New York, 365 Fifth Avenue, New York, NY 10016 (United States)

2009-11-16

General relativity can have a significant impact on the long-range escape trajectories of solar sails deployed near the sun. For example, spacetime curvature in the vicinity of the sun can cause a solar sail traveling from about 4 solar radii to 2550 AU to be deflected by on the order of a million kilometers, and should therefore be taken into account at the beginning of the mission. There are a number of smaller general relativistic effects, such as frame dragging due to the slow rotation of the sun which can cause a deflection of more than one thousand kilometers.

Escape trajectories of solar sails and general relativity

International Nuclear Information System (INIS)

Kezerashvili, Roman Ya.; Vazquez-Poritz, Justin F.

2009-01-01

General relativity can have a significant impact on the long-range escape trajectories of solar sails deployed near the sun. For example, spacetime curvature in the vicinity of the sun can cause a solar sail traveling from about 4 solar radii to 2550 AU to be deflected by on the order of a million kilometers, and should therefore be taken into account at the beginning of the mission. There are a number of smaller general relativistic effects, such as frame dragging due to the slow rotation of the sun which can cause a deflection of more than one thousand kilometers.

Effects of solar radiation on the orbits of small particles

Science.gov (United States)

Lyttleton, R. A.

1976-01-01

A modification of the Robertson (1937) equations of particle motion in the presence of solar radiation is developed which allows for partial reflection of sunlight as a result of rapid and varying particle rotations caused by interaction with the solar wind. The coefficients and forces in earlier forms of the equations are compared with those in the present equations, and secular rates of change of particle orbital elements are determined. Orbital dimensions are calculated in terms of time, probable sizes and densities of meteoric and cometary particles are estimated, and times of infall to the sun are computed for a particle moving in an almost circular orbit and a particle moving in an elliptical orbit of high eccentricity. Changes in orbital elements are also determined for particles from a long-period sun-grazing comet. The results show that the time of infall to the sun from a highly eccentric orbit is substantially shorter than from a circular orbit with a radius equal to the mean distance in the eccentric orbit. The possibility is considered that the free orbital kinetic energy of particles drawn into the sun may be the energy source for the solar corona.

The effect of cover geometry on the productivity of a modified solar still desalination unit

KAUST Repository

Malaeb, Lilian

2014-01-01

Desalination methods based on renewable energy offer a promising solution to both water shortage and environmental degradation problems that continue to grow globally. The solar still is one such method that uses a sustainable energy source to produce potable water albeit at a relatively low productivity rate. A new modification has been introduced to the conventional solar still to enhance its productivity. The modification consists of a light weight, black finished, slowly-rotating drum, which leads to a sustainable, cost-effective, and low-tech amendment that preserves the key features of the still while considerably increasing its yield compared to a control still that does not include the drum. In this paper, three different cover geometries of the modified still are studied and the effect of cover design on the performance of the still in terms of measured temperatures and productivity is considered. The three cover designs are as follows: double-sloped or triangular, single-sloped and curved cover. In addition, a conventional double-sloped still without the rotating drum is operated in parallel as a control and the findings of this study are reported and discussed. © 2014 Published by Elsevier Ltd.

Solar ultraviolet irradiance variations: a review

International Nuclear Information System (INIS)

Lean, J.

1987-01-01

Despite the geophysical importance of solar ultraviolet radiation, specific aspects of its temporal variations have not yet been adequately determined experimentally, nor are the mechanisms for the variability completely understood. Satellite observations have verified the reality of solar ultraviolet irradiance variations over time scales of days and months, and model calculations have confirmed the association of these short-term variations with the evolution and rotation of regions of enhanced magnetic activity on the solar disc. However, neither rocket nor satellite measurements have yet been made with sufficient accuracy and regularity to establish unequivocally the nature of the variability over the longer time of the 11-year solar cycle. The comparative importance for the long-term variations of local regions of enhanced magnetic activity and global scale activity perturbations is still being investigated. Solar ultraviolet irradiance variations over both short and long time scales are reviewed, with emphasis on their connection to solar magnetic activity. Correlations with ground-based measures of solar variability are examined because of the importance of the ground-based observations as historical proxies of ultraviolet irradiance variations. Current problems in understanding solar ultraviolet irradiance variations are discussed, and the measurements planned for solar cycle 22, which may resolve these problems, are briefly described. copyright American Geophysical Union 1987

Properties and geoeffectiveness of magnetic clouds in the rising, maximum and early declining phases of solar cycle 23

Directory of Open Access Journals (Sweden)

K. E. J. Huttunen

2005-02-01

Full Text Available The magnetic structure and geomagnetic response of 73 magnetic clouds (MC observed by the WIND and ACE satellites in solar cycle 23 are examined. The results have been compared with the surveys from the previous solar cycles. The preselected candidate MC events were investigated using the minimum variance analysis to determine if they have a flux-rope structure and to obtain the estimation for the axial orientation (θC, φC. Depending on the calculated inclination relative to the ecliptic we divided MCs into "bipolar" (θC<45° and "unipolar" (θC>45°. The number of observed MCs was largest in the early rising phase, although the halo CME rate was still low. It is likely that near solar maximum we did not identify all MCs at 1AU, as they were crossed far from the axis or they had interacted strongly with the ambient solar wind or with other CMEs. The occurrence rate of MCs at 1AU is also modified by the migration of the filament sites on the Sun towards the poles near solar maximum and by the deflection of CMEs towards the equator due to the fast solar wind flow from large polar coronal holes near solar minimum. In the rising phase nearly all bipolar MCs were associated with the rotation of the magnetic field from the south at the leading edge to the north at the trailing edge. The results for solar cycles 21-22 showed that the direction of the magnetic field in the leading portion of the MC starts to reverse at solar maximum. At solar maximum and in the declining phase (2000-2003 we observed several MCs with the rotation from the north to the south. We observed unipolar (i.e. highly inclined MCs frequently during the whole investigated period. For solar cycles 21-22 the majority of MCs identified in the rising phase were bipolar while in the declining phase most MCs were unipolar. The geomagnetic response of a given MC depends greatly on its magnetic structure and the orientation of the sheath fields. For each event we distinguished the

Transverse mixing of ellipsoidal particles in a rotating drum

Directory of Open Access Journals (Sweden)

He Siyuan

2017-01-01

Full Text Available Rotating drums are widely used in industry for mixing, milling, coating and drying processes. In the past decades, mixing of granular materials in rotating drums has been extensively investigated, but most of the studies are based on spherical particles. Particle shape has an influence on the flow behaviour and thus mixing behaviour, though the shape effect has as-yet received limited study. In this work, discrete element method (DEM is employed to study the transverse mixing of ellipsoidal particles in a rotating drum. The effects of aspect ratio and rotating speed on mixing quality and mixing rate are investigated. The results show that mixing index increases exponentially with time for both spheres and ellipsoids. Particles with various aspect ratios are able to reach well-mixed states after sufficient revolutions in the rolling or cascading regime. Ellipsoids show higher mixing rate when rotational speed is set between 25 and 40 rpm. The relationship between mixing rate and aspect ratio of ellipsoids is established, demonstrating that, particles with aspect ratios of 0.5 and 2.0 achieve the highest mixing rates. Increasing rotating speed from 15 rpm to 40 rpm does not necessarily increase the mixing speed of spheres, while monotonous increase is observed for ellipsoids.

Regulating forest rotation to increase CO{sub 2} sequestration

Energy Technology Data Exchange (ETDEWEB)

Gong, P.; Kristroem, B.

1999-06-01

Previous studies have shown that the optimal forest rotation age increases considerably if the benefits of CO{sub 2} sequestration are included in rotation decisions. While these studies provide some guidelines for managing public forests, private forest owners may not choose the socially optimal rotation age. This paper discusses a regulation measure to increase CO{sub 2} sequestration in privately owned forests. The regulation problem is treated as a sequential game, where the regulator chooses a subsidy scheme and forest owners respond by changing rotation ages. A private forest owner receives a subsidy at the time of harvesting if he/she changes the rotation age towards the socially optimal one. The subsidy is proportional to the associated change in timber yield. The forest owner`s objective is to maximize the net present value of after-tax timber production profits and subsidies. The regulator`s decision problem is to find the subsidy rate that maximizes the net benefits of implementing the policy (the net of increased CO{sub 2} sequestration benefits, subsidy costs, and changes in forestry taxation income). Empirical results for Swedish examples show that the optimal subsidy rate is sensitive to the marginal benefit of CO{sub 2} sequestration, the social discount rate, and site quality. The optimal subsidy rate is found to be significantly lower than the marginal benefit of CO{sub 2} sequestration. With the proposed subsidy scheme, private forest owners will choose rotation ages longer than the Faustmann rotation, but significantly shorter than the socially optimal rotation age 21 refs, 6 tabs. Arbetsrapport 272

K2 & Solar System Science

Science.gov (United States)

Lissauer, Jack

2015-01-01

All of the fields that K2 observes are near the ecliptic plane in order to minimize the spin-up of the spacecraft in response to the effects of solar irradiation. The fields observed by K2 are thus rich in Solar System objects including planets, asteroids and trans-Neptunian objects (TNOs). K2 has already performed observations of Neptune and its large moon Triton, 68 Trojan and Hilda asteroids, 5 TNOs (including Pluto) and Comet C/2013 A1 (Siding Springs). About 10,000 main-belt asteroids that fell into the pixel masks of stars have been serendipitously observed. Observations of small bodies are especially useful for determining rotation periods. Uranus will be observed in a future campaign (C8), as will many more small Solar System bodies. The status of various K2 Solar System studies will be reviewed and placed within the context of our current knowledge of the objects being observed.

Rotation of a Moonless Earth

Science.gov (United States)

Lissauer, Jack J.; Barnes, Jason W.; Chambers, John E.

2013-01-01

We numerically explore the obliquity (axial tilt) variations of a hypothetical moonless Earth. Previous work has shown that the Earth's Moon stabilizes Earth's obliquity such that it remains within a narrow range, between 22.1 deg and 24.5 deg. Without lunar influence, a frequency-map analysis by Laskar et al. showed that the obliquity could vary between 0 deg. and 85 deg. This has left an impression in the astrobiology community that a large moon is necessary to maintain a habitable climate on an Earth-like planet. Using a modified version of the orbital integrator mercury, we calculate the obliquity evolution for moonless Earths with various initial conditions for up to 4 Gyr. We find that while obliquity varies significantly more than that of the actual Earth over 100,000 year timescales, the obliquity remains within a constrained range, typically 20-25 deg. in extent, for timescales of hundreds of millions of years. None of our Solar System integrations in which planetary orbits behave in a typical manner show obliquity accessing more than 65% of the full range allowed by frequency-map analysis. The obliquities of moonless Earths that rotate in the retrograde direction are more stable than those of pro-grade rotators. The total obliquity range explored for moonless Earths with rotation periods shorter than 12 h is much less than that for slower-rotating moonless Earths. A large moon thus does not seem to be needed to stabilize the obliquity of an Earth-like planet on timescales relevant to the development of advanced life.

On generating counter-rotating streamwise vortices

KAUST Repository

Winoto, S H

2015-09-23

Counter-rotating streamwise vortices are known to enhance the heat transfer rate from a surface and also to improve the aerodynamic performance of an aerofoil. In this paper, some methods to generate such counter-rotating vortices using different methods or physical conditions will be briefly considered and discussed.

On generating counter-rotating streamwise vortices

KAUST Repository

Winoto, S H; Mitsudharmadi, Hatsari; Budiman, A C; Hasheminejad, S M; Nadesan, T; Tandiono; Low, H T; Lee, T S

2015-01-01

Counter-rotating streamwise vortices are known to enhance the heat transfer rate from a surface and also to improve the aerodynamic performance of an aerofoil. In this paper, some methods to generate such counter-rotating vortices using different methods or physical conditions will be briefly considered and discussed.

Detection of solar neutrinos with a torsion balance with sapphire crystal

Science.gov (United States)

Cruceru, M.; Nicolescu, G.

2018-01-01

The solar neutrinos (antineutrinos) are detected with a dedicated torsion balance in the case when they interact coherently on stiff crystals (sapphire with high Debye temperature ∼1000K and lead with ∼100K Debye temperature). The balance consists in two equal masses of lead and sapphire, of 25g. An autocollimator coupled to this balance measures small rotation angles of the balance. The force with which neutrino flux interacts with these crystals is between 10-5 dyn and 10-8 dyn, comparable with that reported in Weber’s experiments [1]. A diurnal effect is observed for solar neutrinos due to the rotation of the Earth around its own axes. The solar neutrino flux obtained at the site of our experiment is ∼3.8*1010neutrinos/cm2*s [2]. Experimental data for neutrinos signals from this high sensitivity torsion balance are presented and commented [3].

Effects of dynamic long-period ocean tides on changes in earth's rotation rate

Science.gov (United States)

Nam, Young; Dickman, S. R.

1990-01-01

As a generalization of the zonal response coefficient first introduced by Agnew and Farrell (1978), the zonal response function kappa of the solid earth-ocean system is defined as the ratio, in the frequency domain, of the tidal change in earth's rotation rate to the tide-generating potential. Amplitudes and phases of kappa for the monthly, fortnightly, and nine-day lunar tides are estimated from 2 1/2 years of VLBI UT1 observations, corrected for atmospheric angular momentum effects using NMC wind and pressure series. Using the dynamic ocean tide model of Dickman (1988, 1989), amplitudes and phases of kappa for an elastic earth-ocean system are predicted. The predictions confirm earlier results which found that dynamic effects of the longer-period ocean tides reduce the amplitude of kappa by about 1 percent.

Rotating positron tomographs revisited

International Nuclear Information System (INIS)

Townsend, D.; Defrise, M.; Geissbuhler, A.

1994-01-01

We have compared the performance of a PET scanner comprising two rotating arrays of detectors with that of the more conventional stationary-ring design. The same total number of detectors was used in each, and neither scanner had septa. For brain imaging, we find that the noise-equivalent count rate is greater for the rotating arrays by a factor of two. Rotating arrays have a sensitivity profile that peaks in the centre of the field of view, both axially and transaxially. In the transaxial plane, this effect offsets to a certain extent the decrease in the number of photons detected towards the centre of the brain due to self-absorption. We have also compared the performance of a rotating scanner to that of a full-ring scanner with the same number of rings. We find that a full-ring scanner with an axial extent of 16.2 cm (24 rings) is a factor of 3.5 more sensitive than a rotating scanner with 40% of the detectors and the same axial extent. (Author)

Solar array deployment analysis considering path-dependent behavior of a tape spring hinge

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyung Won; Park, Young Jin [KAIST, Daejeon (Korea, Republic of)

2015-05-15

Solar array deployment analysis is conducted considering the path-dependent nonlinear behavior of tape spring hinge. Such hinges offer many advantages over rigid hinges; they are self-deployable, self-locking, lightweight, and simple. However, they show strongly nonlinear behavior with respect to rotation angle, making deployment analysis difficult. To accurately consider the characteristics of tape spring hinges for deployment analysis, a path-dependent path identification (PI) method for tracing the previous path of the moment is introduced. To analyze the deployment motion, the governing equation for solar array deployment is derived within the framework of Kane's dynamic equation for three deployable solar panels. The numerical solution is compared with the Recurdyn's multi-body dynamics analysis solution using experimentally measured moment-rotation profiles. Solar array deployment analysis is conducted by considering and not considering the path-dependent PI method. This simulation example shows that the proposed path-dependent PI method is very effective for accurately predicting the deployment motion.

Modeling the solar cycle change in nitric oxide in the thermosphere and upper mesosphere

International Nuclear Information System (INIS)

Fuller-Rowell, T.J.

1993-01-01

Measurements from the Solar Mesosphere Explorer (SME) satellite have shown that low-latitude nitric oxide densities at 110 km decrease by about a factor of 8 from January 1982 to April 1985. This time period corresponds to the descending phase of the last solar cycle where the monthly smoothed sunspot number decreased from more than 150 to less than 25. In addition, nitric oxide was observed to vary by a factor of 2 over a solar rotation, during high solar activity. A one-dimensional, globally averaged model of the thermosphere and upper mesosphere has been used to study the height distribution of nitric oxide (NO) and its response to changes in the solar extreme ultraviolet radiation (EUV) through the solar cycle and over a solar rotation. The primary source of nitric oxide is the reaction of excited atomic nitrogen, N( 2 D), with molecular oxygen. The atomic nitrogen is created by a number of ion-neutral reactions and by direct dissociation of molecular nitrogen by photons and photoelectrons. The occurrence of the peak nitric oxide density at or below 115 km is a direct consequence of ionization and dissociation of molecular nitrogen by photoelectrons, which are produced by the solar flux below 30.0 nm (XUV). Nitric oxide is shown to vary over the solar cycle by a factor of 7 at low latitudes in the lower thermosphere E region, due to the estimated change in the solar EUV flux, in good agreement with the SME satellite observations. The NO density is shown to be strongly dependent on the temperature profile in the lower thermosphere and accounts for the difference between the current model and previous work. Wavelengths less than 1.8 nm have little impact on the NO profile. A factor of 3 change in solar flux below 5.0 nm at high solar activity produced a factor of 2 change in the peak NO density, consistent with SME observations over a solar rotation; this change also lowered the peak to 100 km, consistent with rocket data. 52 refs., 10 figs., 5 tabs

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

75 FR 76726 - San Luis Solar, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

Science.gov (United States)

2010-12-09

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER11-2196-000] San Luis Solar, LLC; Supplemental Notice That Initial Market- Based Rate Filing Includes Request for Blanket... proceeding of San Luis [[Page 76727

Is position of solar system in the Galaxy anything exceptional

International Nuclear Information System (INIS)

Marochnik, L.

1984-01-01

The latest astrophysical knowledge shows that the solar system is in the vicinity of the so-called corotation circle. It rotates around the nucleus of the galaxy almost synchronously with the density wave, i.e., with the spiral structure, which has created specific conditions for the development of the pre-solar cloud from which has evolved our solar system. This development took place between the arms of the galaxy, i.e., in a relatively calm area which probably made possible the origin of life. (Ha)

Effect of vanadium carbide on dry sliding wear behavior of powder metallurgy AISI M2 high speed steel processed by concentrated solar energy

Energy Technology Data Exchange (ETDEWEB)

García, C. [Materials Engineering. E.I.I., Universidad de Valladolid. C/Paseo del cauce 59, 47011 Valladolid (Spain); Romero, A. [E.T.S. Ingenieros Industriales. Instituto de Investigaciones Energéticas y Aplicaciones Industriales (INEI). Universidad de Castilla-La Mancha, Edificio Politécnico, Avda. Camilo José Cela s/n, 13071 Ciudad Real (Spain); Herranz, G., E-mail: gemma.herranz@uclm.es [E.T.S. Ingenieros Industriales. Instituto de Investigaciones Energéticas y Aplicaciones Industriales (INEI). Universidad de Castilla-La Mancha, Edificio Politécnico, Avda. Camilo José Cela s/n, 13071 Ciudad Real (Spain); Blanco, Y.; Martin, F. [Materials Engineering. E.I.I., Universidad de Valladolid. C/Paseo del cauce 59, 47011 Valladolid (Spain)

2016-11-15

Mixtures of AISI M2 high speed steel and vanadium carbide (3, 6 or 10 wt.%) were prepared by powder metallurgy and sintered by concentrated solar energy (CSE). Two different powerful solar furnaces were employed to sinter the parts and the results were compared with those obtained by conventional powder metallurgy using a tubular electric furnace. CSE allowed significant reduction of processing times and high heating rates. The wear resistance of compacts was studied by using rotating pin-on-disk and linearly reciprocating ball-on-flat methods. Wear mechanisms were investigated by means of scanning electron microscopy (SEM) observations and chemical inspections of the microstructures of the samples. Better wear properties than those obtained by conventional powder metallurgy were achieved. The refinement of the microstructure and the formation of carbonitrides were the reasons for this. - Highlights: •Powder metallurgy of mixtures of M2 high speed steel and VC are studied. •Some sintering is done by concentrated solar energy. •Rotating pin-on-disk and linearly reciprocating ball-on-flat methods are used. •The tribological properties and wear mechanisms, under dry sliding, are studied.

Physics of rotation: problems and challenges

Science.gov (United States)

Maeder, Andre; Meynet, Georges

2015-01-01

We examine some debated points in current discussions about rotating stars: the shape, the gravity darkening, the critical velocities, the mass loss rates, the hydrodynamical instabilities, the internal mixing and N-enrichments. The study of rotational mixing requires high quality data and careful analysis. From recent studies where such conditions are fulfilled, rotational mixing is well confirmed. Magnetic coupling with stellar winds may produce an apparent contradiction, i.e. stars with a low rotation and a high N-enrichment. We point out that it rather confirms the large role of shears in differentially rotating stars for the transport processes. New models of interacting binaries also show how shears and mixing may be enhanced in close binaries which are either spun up or down by tidal interactions.

The role of plasma induced substrate heating during high rate deposition of microcrystalline solar cells

NARCIS (Netherlands)

van den Donker, M.N.; Schmitz, R.; Appenzeller, W.; Rech, B.; Kessels, W.M.M.; Sanden, van de M.C.M.

2006-01-01

A 13.56 MHz parallel plate hydrogen-dild. silane plasma, operated at high pressure and high power, was used to deposit microcryst. silicon solar cells with efficiencies of 6-9% at high deposition rates of 0.4-1.2 nm/s. In this regime new challenges arise regarding temp. control, since the high

Optimising position control of a solar parabolic trough

Directory of Open Access Journals (Sweden)

Puramanathan Naidoo

2011-03-01

Full Text Available In today’s climate of growing energy needs and increasing environmental concerns, alternatives to the use of non-renewable and polluting fossil fuels have to be investigated. One such alternative is solar energy. This study is based on the implementation of a mathematical computation – the PSA (Plataforma Solar de Almeria computation developed at PSA (the European Test Centre for solar energy applications – embedded in a control algorithm to locate the position of the sun. Tests were conducted on a solar parabolic trough (SPT constructed at the Solar Thermal Applications Research Laboratory of the Mangosuthu University of Technology (Durban, South Africa for optimal position control using the PSA value. The designed control algorithm embedded in an industrial Siemens S7-314 C-2PtP programmable logic controller compared the PSA computation to a measured position of the SPT to optimally rotate the SPT to a desired position with the constant movement of the sun. The two main angles of the sun relative to the position of the SPT on earth, the zenith angle and the azimuth angle, both calculated in the PSA from the vertical and horizontal planes, respectively, were applied to the control algorithm to generate an appropriate final tracking angle within a 0.007 radian (0° 24′ 3.6″ tolerance, in accordance to the construction specifications and solar collector testing standards of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE, 1991. These values, together with the longitude and latitude applicable to the geographical location of the SPT, were processed in the control software to rotate the SPT to an optimal position with respect to the position of the sun in its daily path, for solar-to-thermal conversion.

A cyclostrophic transformed Eulerian zonal mean model for the middle atmosphere of slowly rotating planets

Science.gov (United States)

Li, K. F.; Yao, K.; Taketa, C.; Zhang, X.; Liang, M. C.; Jiang, X.; Newman, C. E.; Tung, K. K.; Yung, Y. L.

2015-12-01

With the advance of modern computers, studies of planetary atmospheres have heavily relied on general circulation models (GCMs). Because these GCMs are usually very complicated, the simulations are sometimes difficult to understand. Here we develop a semi-analytic zonally averaged, cyclostrophic residual Eulerian model to illustrate how some of the large-scale structures of the middle atmospheric circulation can be explained qualitatively in terms of simple thermal (e.g. solar heating) and mechanical (the Eliassen-Palm flux divergence) forcings. This model is a generalization of that for fast rotating planets such as the Earth, where geostrophy dominates (Andrews and McIntyre 1987). The solution to this semi-analytic model consists of a set of modified Hough functions of the generalized Laplace's tidal equation with the cyclostrohpic terms. As examples, we apply this model to Titan and Venus. We show that the seasonal variations of the temperature and the circulation of these slowly-rotating planets can be well reproduced by adjusting only three parameters in the model: the Brunt-Väisälä bouyancy frequency, the Newtonian radiative cooling rate, and the Rayleigh friction damping rate. We will also discuss the application of this model to study the meridional transport of photochemically produced tracers that can be observed by space instruments.

On the Origins of the Intercorrelations Between Solar Wind Variables

Science.gov (United States)

Borovsky, Joseph E.

2018-01-01

It is well known that the time variations of the diverse solar wind variables at 1 AU (e.g., solar wind speed, density, proton temperature, electron temperature, magnetic field strength, specific entropy, heavy-ion charge-state densities, and electron strahl intensity) are highly intercorrelated with each other. In correlation studies of the driving of the Earth's magnetosphere-ionosphere-thermosphere system by the solar wind, these solar wind intercorrelations make determining cause and effect very difficult. In this report analyses of solar wind spacecraft measurements and compressible-fluid computer simulations are used to study the origins of the solar wind intercorrelations. Two causes are found: (1) synchronized changes in the values of the solar wind variables as the plasma types of the solar wind are switched by solar rotation and (2) dynamic interactions (compressions and rarefactions) in the solar wind between the Sun and the Earth. These findings provide an incremental increase in the understanding of how the Sun-Earth system operates.

Regional wall thickening in gated myocardial perfusion SPECT in a Japanese population: effect of sex, radiotracer, rotation angles and frame rates

Energy Technology Data Exchange (ETDEWEB)

Akhter, Nasima; Nakajima, Kenichi; Okuda, Koichi; Matsuo, Shinro; Yoneyama, Tatsuya; Taki, Junichi; Kinuya, Seigo [Kanazawa University Hospital, Department of Nuclear Medicine, Kanazawa, Ishikawa (Japan)

2008-09-15

Gated single-photon emission computed tomography (SPECT) imaging of myocardium by {sup 99m}Tc and {sup 201}Tl is used extensively to measure quantitative cardiac functional parameters. However, factors affecting normal values for myocardial functional parameters and population-specific standards have not yet been established. The aim of the study was to determine the effect of sex, radiotracer, rotation angles and frame rates on resting myocardial wall thickening (WT) and to develop a Japanese standard of normal values for WT. Data from a total of 202 patients with low possibility of having cardiac problems were collected from nine hospitals throughout Japan. Patients were divided into five groups according to study protocol, and WT was evaluated according to the 17-segment and four-region (basal, mid and apical regions and the apex) polar map distribution. WT was generally higher in women than in men irrespective of the use of radiotracers, rotation angles or frame rates, and the difference was highly significant in the mid and apical regions. In any protocol used, resting myocardial thickening in the apex was higher than in the mid and apical regions, and thickening was lowest in the basal region, suggesting heterogeneous regional myocardial thickening (%) in normal subjects. Different rotation angles showed no significant change on WT, but different frame rates and tracers showed significant WT change in both sexes. Percent thickening of the myocardium was significantly higher in imaging by {sup 99m}Tc-labelled tracers than in {sup 201}Tl. Sex, radiotracers and frame rates had a significant effect on myocardial thickening, and the importance of population-specific standards should be emphasized. A normal database can serve as a standard for gated SPECT evaluation of myocardial thickening in a Japanese population and might be applicable to Asian populations having a similar physique. (orig.)

78 FR 34373 - Campo Verde Solar, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

Science.gov (United States)

2013-06-07

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-1541-000] Campo Verde Solar, LLC; Supplemental Notice That Initial Market- Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding of Campo Verde...

76 FR 63614 - Agua Caliente Solar, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

Science.gov (United States)

2011-10-13

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER12-21-000] Agua Caliente Solar, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding of Agua...

Solar active region display system

Science.gov (United States)

Golightly, M.; Raben, V.; Weyland, M.

2003-04-01

The Solar Active Region Display System (SARDS) is a client-server application that automatically collects a wide range of solar data and displays it in a format easy for users to assimilate and interpret. Users can rapidly identify active regions of interest or concern from color-coded indicators that visually summarize each region's size, magnetic configuration, recent growth history, and recent flare and CME production. The active region information can be overlaid onto solar maps, multiple solar images, and solar difference images in orthographic, Mercator or cylindrical equidistant projections. Near real-time graphs display the GOES soft and hard x-ray flux, flare events, and daily F10.7 value as a function of time; color-coded indicators show current trends in soft x-ray flux, flare temperature, daily F10.7 flux, and x-ray flare occurrence. Through a separate window up to 4 real-time or static graphs can simultaneously display values of KP, AP, daily F10.7 flux, GOES soft and hard x-ray flux, GOES >10 and >100 MeV proton flux, and Thule neutron monitor count rate. Climatologic displays use color-valued cells to show F10.7 and AP values as a function of Carrington/Bartel's rotation sequences - this format allows users to detect recurrent patterns in solar and geomagnetic activity as well as variations in activity levels over multiple solar cycles. Users can customize many of the display and graph features; all displays can be printed or copied to the system's clipboard for "pasting" into other applications. The system obtains and stores space weather data and images from sources such as the NOAA Space Environment Center, NOAA National Geophysical Data Center, the joint ESA/NASA SOHO spacecraft, and the Kitt Peak National Solar Observatory, and can be extended to include other data series and image sources. Data and images retrieved from the system's database are converted to XML and transported from a central server using HTTP and SOAP protocols, allowing

The rotation of galaxy clusters

International Nuclear Information System (INIS)

Tovmassian, H.M.

2015-01-01

The method for detection of the galaxy cluster rotation based on the study of distribution of member galaxies with velocities lower and higher of the cluster mean velocity over the cluster image is proposed. The search for rotation is made for flat clusters with a/b> 1.8 and BMI type clusters which are expected to be rotating. For comparison there were studied also round clusters and clusters of NBMI type, the second by brightness galaxy in which does not differ significantly from the cluster cD galaxy. Seventeen out of studied 65 clusters are found to be rotating. It was found that the detection rate is sufficiently high for flat clusters, over 60 per cent, and clusters of BMI type with dominant cD galaxy, ≈ 35 per cent. The obtained results show that clusters were formed from the huge primordial gas clouds and preserved the rotation of the primordial clouds, unless they did not have mergings with other clusters and groups of galaxies, in the result of which the rotation has been prevented

The search for solar neutrinos

International Nuclear Information System (INIS)

Ryder, L.

1976-01-01

The pioneering work on the detection of solar neutrinos by R. Davis is discussed. The discrepancy between the theoretical neutrino flux rate, according to a recent standard solar model, of 5.6 solar neutrino units (SNU) and the observed rate of 1 SNU together with three suggested solutions of the discrepancy are examined. Very recently Davis has announced an increased count rate of about 4 SNU while groups in Birmingham and in the Crimea have reported solar oscillations. The impact of these latest developments is discussed. (U.K.)

Solar thermal barometer

International Nuclear Information System (INIS)

Anon.

2004-01-01

After the bad year of 2002, the european solar thermal market returned to double-digit growth rate in 2003: 22%. Nevertheless, the sector still has not recovered the growth rate it had in the early 2000 and European Commission targets are still far from being reached. This paper presents the thermal solar industry barometer. Data on the evolution of annually installed surfaces in the european union since 1993, the cumulated capacity of thermal collectors installed in the European Union, the estimation of the annual energy production associated to european solar thermal capacities and the main companies of the European Union thermal solar sector are presented and discussed. (A.L.B.)

Development of a Learning Progression for the Formation of the Solar System

Science.gov (United States)

Plummer, Julia D.; Palma, Christopher; Flarend, Alice; Rubin, KeriAnn; Ong, Yann Shiou; Botzer, Brandon; McDonald, Scott; Furman, Tanya

2015-01-01

This study describes the process of defining a hypothetical learning progression (LP) for astronomy around the big idea of "Solar System formation." At the most sophisticated level, students can explain how the formation process led to the current Solar System by considering how the planets formed from the collapse of a rotating cloud of…

Effect of brining on the drying rate of tilapia in a solar tunnel dryer

Energy Technology Data Exchange (ETDEWEB)

Kituu, G.M.; Shitanda, D.; Kanali, C.L.; Mailutha, J.T. [Jomo Kenyatta Univ. of Agriculture and Technology, Nairobi (Kenya). BEED

2008-07-01

In addition to being a source of protein, fish is an important source of local and foreign currency earnings in Kenya. A substantial amount of fish production is exported. Approximately 30 per cent is exported to the European Union, the United States, and countries in the Middle East, but nearly half of the total annual fish harvest in Kenya goes to waste due to poor processing and preservation. Measures must be taken to ensure the fish industry is protected and waste is minimized, since the livelihood of over 500,000 people depends on fish as a source of proteins and employment. Therefore, it is necessary to implement appropriate and affordable processing and preservation techniques for fish at the artisanal landing sites in order to reduce the wastage and spoilage of fish during oversupply, and to enhance long storage. This paper presented studies that were conducted to determine the effect of brining on the drying rate of tilapia in a solar tunnel dryer. The paper discussed the materials and methods, including a description of the solar tunnel dryer system; the brining process of fish; the fish drying process; and data analysis. It was concluded that limiting the amount of salt used in brining, and subsequently dehydrating fish with a solar tunnel dryer achieves a more stable and suitable dried fish product than osmotic dehydration or solar drying process separately. 19 refs., 5 figs., 2 appendices.

Void fraction and velocity measurement of simulated bubble in a rotating disc using high frame rate neutron radiography.

Science.gov (United States)

Saito, Y; Mishima, K; Matsubayashi, M

2004-10-01

To evaluate measurement error of local void fraction and velocity field in a gas-molten metal two-phase flow by high-frame-rate neutron radiography, experiments using a rotating stainless-steel disc, which has several holes of various diameters and depths simulating gas bubbles, were performed. Measured instantaneous void fraction and velocity field of the simulated bubbles were compared with the calculated values based on the rotating speed, the diameter and the depth of the holes as parameters and the measurement error was evaluated. The rotating speed was varied from 0 to 350 rpm (tangential velocity of the simulated bubbles from 0 to 1.5 m/s). The effect of shutter speed of the imaging system on the measurement error was also investigated. It was revealed from the Lagrangian time-averaged void fraction profile that the measurement error of the instantaneous void fraction depends mainly on the light-decay characteristics of the fluorescent converter. The measurement error of the instantaneous local void fraction of simulated bubbles is estimated to be 20%. In the present imaging system, the light-decay characteristics of the fluorescent converter affect the measurement remarkably, and so should be taken into account in estimating the measurement error of the local void fraction profile.

Void fraction and velocity measurement of simulated bubble in a rotating disc using high frame rate neutron radiography

International Nuclear Information System (INIS)

Saito, Y.; Mishima, K.; Matsubayashi, M.

2004-01-01

To evaluate measurement error of local void fraction and velocity field in a gas-molten metal two-phase flow by high-frame-rate neutron radiography, experiments using a rotating stainless-steel disc, which has several holes of various diameters and depths simulating gas bubbles, were performed. Measured instantaneous void fraction and velocity field of the simulated bubbles were compared with the calculated values based on the rotating speed, the diameter and the depth of the holes as parameters and the measurement error was evaluated. The rotating speed was varied from 0 to 350 rpm (tangential velocity of the simulated bubbles from 0 to 1.5 m/s). The effect of shutter speed of the imaging system on the measurement error was also investigated. It was revealed from the Lagrangian time-averaged void fraction profile that the measurement error of the instantaneous void fraction depends mainly on the light-decay characteristics of the fluorescent converter. The measurement error of the instantaneous local void fraction of simulated bubbles is estimated to be 20%. In the present imaging system, the light-decay characteristics of the fluorescent converter affect the measurement remarkably, and so should be taken into account in estimating the measurement error of the local void fraction profile

Some studies relating to solar-terrestrial physics and the middle atmosphere

International Nuclear Information System (INIS)

Theobald, A.G.

1977-12-01

A review is given of observed variations in the Earth's rotation rate, and mechanisms by which the Sun might affect the length of day are discussed. Solar activity and means by which the planets might influence this activity are considered. Observed solar activity - weather correlations, in particular in relation to the sun-based, interplanetary magnetic sector structure and some of the suggested mechanisms for producing these correlations are discussed. The simple photochemical production of ozone in the middle atmosphere and the manner in which cosmic rays, through the production of nitrogen compounds, alter the ozone concentration at high altitudes is described. A computer model is developed which calculates ozone concentrations and energy absorption at any altitude, latitude, longitude and time of year and used to predict ozone and temperature change profiles over a 14-day cycle of ultra-violet changes. The existence of a solar magnetic sector linked variation of the high latitude, high altitude NO concentration is postulated and this is incorporated into the computer model to predict a temperature oscillation over a 14-day cycle which varies with geographic latitude and longitude. This effect is investigated in detail. (UK)

The turbulent cascade and proton heating in the solar wind during solar minimum

International Nuclear Information System (INIS)

Coburn, Jesse T.; Smith, Charles W.; Vasquez, Bernard J.; Stawarz, Joshua E.; Forman, Miriam A.

2013-01-01

Solar wind measurements at 1 AU during the recent solar minimum and previous studies of solar maximum provide an opportunity to study the effects of the changing solar cycle on in situ heating. Our interest is to compare the levels of activity associated with turbulence and proton heating. Large-scale shears in the flow caused by transient activity are a source that drives turbulence that heats the solar wind, but as the solar cycle progresses the dynamics that drive the turbulence and heat the medium are likely to change. The application of third-moment theory to Advanced Composition Explorer (ACE) data gives the turbulent energy cascade rate which is not seen to vary with the solar cycle. Likewise, an empirical heating rate shows no significan changes in proton heating over the cycle.

From Newton's bucket to rotating polygons

DEFF Research Database (Denmark)

Bach, B.; Linnartz, E. C.; Vested, Malene Louise Hovgaard

2014-01-01

We present an experimental study of 'polygons' forming on the free surface of a swirling water flow in a partially filled cylindrical container. In our set-up, we rotate the bottom plate and the cylinder wall with separate motors. We thereby vary rotation rate and shear strength independently...... and move from a rigidly rotating 'Newton's bucket' flow to one where bottom and cylinder wall are rotating oppositely and the surface is strongly turbulent but flat on average. Between those two extremes, we find polygonal states for which the rotational symmetry is spontaneously broken. We investigate...... the phase diagram spanned by the two rotational frequencies at a given water filling height and find polygons in a regime, where the two frequencies are sufficiently different and, predominantly, when they have opposite signs. In addition to the extension of the family of polygons found with the stationary...

Experimental Investigation of a Solar Greenhouse Heating System Equipped with a Parabolic Trough Solar Concentrator and a Double-Purpose Flat Plate Solar Collector

Directory of Open Access Journals (Sweden)

M Jafari

2017-10-01

stored heat transferred from the collector surface to the greenhouse. The evaluation tests were conducted at three levels of fluid flow rate through the solar concentrator (0.44, 0.75 and 1.5 Lmin-1 and two different working modes of the heat exchanger. Results and Discussion The variation of thermal efficiency of the PTC at different flow rates has been illustrated in Fig 3. As shown, thermal efficiency increased with flow rate mainly because the fluid convection coefficient enhances with raising the velocity of the fluid inside the tubes. The heat storing process began from 9 am and the highest amounts of the stored heat during sunshine time occurred between 10 am and 2 pm. Fig 5 showed that the stored energy in the tank enhanced when the flat plate collector was employed beside the PTC. Also, increasing the fluid flow rate from 0.44 to 1.5 Lmin-1 improved the index of stored heat by 32.14%. Energy consumption during the night time was also significantly changed with flow rate and the mode of heating. Fig 7 indicated that the electrical energy consumption was lower with flat plate solar collector and it is possible to save the electrical energy by 26.67% using the flat plate collector. Bouadila et al., (2014 concluded that the electrical energy consumption reduced by 31% employing a natural convection flat plate solar collector system equipped with phase changed heat storage material for greenhouse heating. Since increasing the flow rate enhanced the thermal efficiency of the solar concentrator system and led to an improvement in stored thermal energy during the sunshine time, solar fraction increased with raising the flow rate from 0.44 to 1.5 Lmin-1. A maximum solar fraction of 66% was achieved at the highest flow rate when using the flat plate solar collector beside the PTC. Conclusions An experimental comparative study was conducted to investigate the performance of a novel solar greenhouse heating system at the different fluid flow rates and two modes of heating

Solar UV radiation variations and their stratospheric and climatic effects

Science.gov (United States)

Donnelly, R. F.; Heath, D. F.

1985-01-01

Nimbus-7 SBUV measurements of the short-term solar UV variations caused by solar rotation and active-region evolution have determined the amplitude and wavelength dependence for the active-region component of solar UV variations. Intermediate-term variations lasting several months are associated with rounds of major new active regions. The UV flux stays near the peak value during the current solar cycle variation for more than two years and peaks about two years later than the sunspot number. Nimbus-7 measurements have observed the concurrent stratospheric ozone variations caused by solar UV variations. There is now no doubt that solar UV variations are an important cause of short- and long-term stratospheric variations, but the strength of the coupling to the troposphere and to climate has not yet been proven.

Solar neighbourhood flare stars - a review

International Nuclear Information System (INIS)

Kunkel, W.E.

1975-01-01

The review concentrates on 'astronomical' aspects of flare activity, such as where, and under what circumstances flare activity is found in the solar vicinity. Non-classical activity is briefly described (without regard for completeness) and the influence of detection effects on flare observations is treated. Flare stars discovered during the last four years are described and flare activity of local dMe stars is compared. The BY Draconis syndrome is discussed followed by some remarks about rotation. Pleiades flare activity is compared to that of the solar neighbourhood and evidence for the evolution of flare activity in stars is examined. (Auth.)

Coherent spin-rotational dynamics of oxygen superrotors

Science.gov (United States)

Milner, Alexander A.; Korobenko, Aleksey; Milner, Valery

2014-09-01

We use state- and time-resolved coherent Raman spectroscopy to study the rotational dynamics of oxygen molecules in ultra-high rotational states. While it is possible to reach rotational quantum numbers up to N≈ 50 by increasing the gas temperature to 1500 K, low population levels and gas densities result in correspondingly weak optical response. By spinning {{O}2} molecules with an optical centrifuge, we efficiently excite extreme rotational states with N≤slant 109 in high-density room temperature ensembles. Fast molecular rotation results in the enhanced robustness of the created rotational wave packets against collisions, enabling us to observe the effects of weak spin-rotation coupling in the coherent rotational dynamics of oxygen. The decay rate of spin-rotational coherence due to collisions is measured as a function of the molecular angular momentum and its dependence on the collisional adiabaticity parameter is discussed. We find that at high values of N, the rotational decoherence of oxygen is much faster than that of the previously studied non-magnetic nitrogen molecules, pointing at the effects of spin relaxation in paramagnetic gases.

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.

Evolutionary period changes in rotating hot pre--white dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Kawaler, S.D.; Winget, D.E.; Hansen, C.J.

1985-11-15

We have calculated and splitting of high order nonradial g-modes due to slow rotation in models of hot pre-white dwarf (''PWD'') stars of 0.60 M/sub sun/. We have investigated the effects of rotational spin-up, produced by gravitational contraction, on the rate of evolutionary period change for the cases of uniform and differential rotation. For models in the luminosity range of PG 1159-035 (Lapprox.100 L/sub sun/), we find that rotation rates of a few thousand seconds for modes with m< or approx. =-2 produce values of d(ln P)/dt that are consistent with the measurement of the rate of period change of the 516 second period of PG 1159-035.

AC electric field induced dipole-based on-chip 3D cell rotation.

Science.gov (United States)

Benhal, Prateek; Chase, J Geoffrey; Gaynor, Paul; Oback, Björn; Wang, Wenhui

2014-08-07

The precise rotation of suspended cells is one of the many fundamental manipulations used in a wide range of biotechnological applications such as cell injection and enucleation in nuclear transfer (NT) cloning. Noticeably scarce among the existing rotation techniques is the three-dimensional (3D) rotation of cells on a single chip. Here we present an alternating current (ac) induced electric field-based biochip platform, which has an open-top sub-mm square chamber enclosed by four sidewall electrodes and two bottom electrodes, to achieve rotation about the two axes, thus 3D cell rotation. By applying an ac potential to the four sidewall electrodes, an in-plane (yaw) rotating electric field is generated and in-plane rotation is achieved. Similarly, by applying an ac potential to two opposite sidewall electrodes and the two bottom electrodes, an out-of-plane (pitch) rotating electric field is generated and rolling rotation is achieved. As a prompt proof-of-concept, bottom electrodes were constructed with transparent indium tin oxide (ITO) using the standard lift-off process and the sidewall electrodes were constructed using a low-cost micro-milling process and then assembled to form the chip. Through experiments, we demonstrate rotation of bovine oocytes of ~120 μm diameter about two axes, with the capability of controlling the rotation direction and the rate for each axis through control of the ac potential amplitude, frequency, and phase shift, and cell medium conductivity. The maximum observed rotation rate reached nearly 140° s⁻¹, while a consistent rotation rate reached up to 40° s⁻¹. Rotation rate spectra for zona pellucida-intact and zona pellucida-free oocytes were further compared and found to have no effective difference. This simple, transparent, cheap-to-manufacture, and open-top platform allows additional functional modules to be integrated to become a more powerful cell manipulation system.

Multibody dynamic analysis using a rotation-free shell element with corotational frame