Frequency Dependence of Double Band Electroluminophors

In the present paper an attempt has been made to study the emission characteristics of the two peaks, blue and green of a (ZnS:Cu) double band electroluminophor, particularly the frequency effect. As regards voltage, both the peaks are found to behave in the usual way but the frequency relations give rise to somewhat new results With a rise in applied field frequency, the green band suffers a peak shift towards lower wavelength side, whereas the blue one is always shouldered and is little affected as far as peak position is concerned. The light output is observed to fall down at higher frequencies instead of showing a constant intensity of emission

A Study on Residual Compression Behavior of Structural Fiber Reinforced Concrete Exposed to Moderate Temperature Using Digital Image Correlation

Fire ranks high among the potential risks faced by most buildings and structures. A full understanding of temperature effects on fiber reinforced concrete is still lacking. This investigation focuses on the study of the residual compressive strength, stress strain behavior and surface cracking of structural polypropylene fiber-reinforced concrete subjected to temperatures up to 300 A degrees C. A total of 48 cubes was cast with different fiber dosages and tested under compression after exposing to different temperatures. Concrete cubes with varying macro (structural) fiber dosages were exposed to different temperatures and tested to observe the stress-strain behavior. Digital image correlation, an advanced non-contacting method was used for measuring the strain. Trends in the relative residual strengths with respect to different fiber dosages indicate an improvement up to 15 % in the ultimate compressive strengths at all exposure temperatures. The stress-strain curves show an improvement in post peak behavior with increasing fiber dosage at all exposure temperatures considered in this study

Characteristics of events with metric-to-decahectometric type II radio bursts associated with CMEs and flares in relation to SEP events

A gradual solar energetic particle (SEP) event is thought to happen when particles are accelerated at a shock due to a fast coronal mass ejection (CME). To quantify what kind of solar eruptions can result in such SEP events, we have conducted detailed investigations on the characteristics of CMEs, solar flares and m-to-DH wavelength type II radio bursts (herein after m-to-DH type II bursts) for SEP-associated and non-SEP-associated events, observed during the period of 1997-2012. Interestingly, 65% of m-to-DH type II bursts associated with CMEs and flares produced SEP events. The SEP-associated CMEs have higher sky-plane mean speed, projection corrected speed, and sky-plane peak speed than those of non-SEP-associated CMEs respectively by 30%, 39%, and 25%, even though the two sets of CMEs achieved their sky-plane peak speeds at nearly similar heights within LASCO field of view. We found Pearson's correlation coefficients between the speeds of CMEs speeds and logarithmic peak intensity of SEP events are cc = 0.62 and cc = 0.58, respectively. We also found that the SEP-associated CMEs are on average of three times more decelerated (-21.52 m/s2) than the non-SEP-associated CMEs (-5.63 m/s2). The SEP-associated m type II bursts have higher frequency drift rate and associated shock speed than those of the non-SEP-associated events by 70% and 25% respectively. The average formation heights of m and DH type II radio bursts for SEP-associated events are lower than for non-SEP-associated events. 93% of SEP-associated events originate from the western hemisphere and 65% of SEP-associated events are associated with interacting CMEs. The obtained results indicate that, at least for the set of CMEs associated with m-to-DH type II bursts, SEP-associated CMEs are more energetic than those not associated with SEPs, thus suggesting that they are effective particle accelerators.Comment: 19 pages, 10 figures, 3 tables, accepted for publication by ApS

Nonlinear Finite-Element Analysis of RC Bridge Columns under Torsion with and without Axial Compression

Finite-element (FE) modeling of RC structures under combined loading has received considerable attention in recent years. However, the combination of torsion and axial compression has been rarely studied in spite of its frequent occurrence in bridge columns under earthquake loading. This paper aims at creating a nonlinear FE model to predict the behavior of RC bridge columns under combined torsion and axial compression. A number of circular and square columns were analyzed. The developed FE model was calibrated on local and global behavior through comparison with test data. The overall torque-twist behavior of the members was captured well by the developed FE models. The predicted values of strain in the longitudinal and transverse reinforcement matched closely with the experimental results. An increase in transverse steel ratio was found to increase the torsional capacity and limit the damage of columns under torsion. It was further observed that at a low level of axial compression, the torsional capacity of columns is enhanced. In addition, the FE analysis showed a good agreement on the identification of the damage mechanism and the progression of failure. The shape of the cross section is found to play a major role in the distribution of torsional damage in the columns. Square columns exhibited a more localized damage due to presence of warping, whereas circular columns exhibited damage distributed along their length. (C) 2015 American Society of Civil Engineers

Pair excitation-deexcitation coherent states

A class of coherent states defined in terms of the excitation and deexcitation of pairs of photons is studied with reference to its nonclassical and other quantum-statistical properties. These states supplement the other well-known two-mode states such as Caves-Schumaker states and pair coherent states and can be produced by dissipative processes involving emission and absorption of photons in pairs

Neutrino Emission From Direct Urca Processes in Pion Condensed Quark Matter

We study neutrino emission from direct Urca processes in pion condensed quark matter. In compact stars with high baryon density, the emission is dominated by the gapless modes of the pion condensation which leads to an enhanced emissivity. While for massless quarks the enhancement is not remarkable, the emissivity is significantly larger and the cooling of the condensed matter is considerably faster than that in normal quark matter when the mass difference between $u$- and $d$-quarks is sizable.Comment: 12 pages,6 figures, published versio

Effect of Muons on the Phase Transition in Magnetised Proto-Neutron Star Matter

We study the effect of inclusion of muons and the muon neutrinos on the phase transition from nuclear to quark matter in a magnetised proto-neutron star and compare our results with those obtained by us without the muons. We find that the inclusion of muons changes slightly the nuclear density at which transition occurs.However the dependence of this transition density on various chemical potentials, temperature and the magnetic field remains quantitatively the same.Comment: LaTex2e file with four postscript figure