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[en] Comets were studied during their relatively quiescent phases at large distances from the sun. This program has resulted in a variety of CCD images of comets in several visible and near-IR bands selected to sample the continuum, rather than emission features. The most extensive dataset was obtained for P/Halley during January 1985 (plus scattered earlier data), near the time the comet turned on. The data were reduced in a preliminary fashion. Other comets predicted to be relatively inactive (including Neujmin 1 and Arend-Rigaux) were most active than expected. P/Gehrels 3 was also observed
[en] Gamma rays have high penetration power and its attenuation depends upon the thickness and the attenuation coefficient of the shield, so it is necessary to use the high density shield to attenuate the gamma rays. Heavy concrete is considered to be used for high radiation laboratory and the testing of the shielding ability and compressibility of various types of heavy concrete composed of baryte, hematite, ilmenite and galena is carried out. The results of this study show that baryte-ilmenite concrete is the most suitable for high radiation laboratory in Thailand
[en] The motion of a cylinder on an inclined plane, acted upon by a torque along its axis, is studied theoretically and experimentally. It is shown that the potential for the centre-of-mass exhibits the features of a fold catastrophe potential, the control parameter being related to the strength of the torque. This parameter determines whether or not the system experiences stable equilibrium positions. If it does, and depending on the initial conditions, it may perform oscillations around an equilibrium position, or it may cross a no-return point and roll down. A cylinder with a magnet inside, placed on an inclined plane in a region where a uniform magnetic field is present, is a real example of such a system. We constructed that system and report the data obtained in a set of experiments
[en] Intellectual nephelometer of open type designed by the authors for in situ studies of the atmosphere are described. The nephlometer operate in near IR wavelength range. The construction and concept of the devices allow them either to work independently during several hours or to be operated remotely at a distance up to 500 m from the central host computer. The results and their analysis of two weeks test at Kumkang Hu-Tech Co. are represented. This Nephelometer is a new class of intellectual instruments intended for long-term application on open air and allowing to receive qualitative and the quantitative information about a scattering coefficient in situ.
[en] The results of UBVR photometry of 30 radio objects with continuous optical spectra (ROCOSes) are reported. The observations were performed using five telescopes during the years 1979-1982; 54 values have been obtained of U, B, V magnitudes and 26 ones of R magnitude. Colours for 16 ROCOSes have been obtained for the first time. The analysis of the data results in the following conclusions. 1) Practically all colours of ROCOSes have proved to be in the region of localization of BL Lac objects' colours on UBV and BVR diagrams. This fact (altogether with the other data) indicates on the proximity of the objects of the two classes. 2) In half of all cases, instantaneous colours of ROCOSes corresponded to purely power-law optical continua F(ν) varies as νsup(α) with α approximately= -(1-2.5). 3) In the remaining cases, optical continua differed significantly from the power-law ones. 4) 6 ROCOSes appeared to be in the phases of deep minimum of brightness at the moment of observations (namely, about 3sup(m)-5sup(m) fainter than in the brightest phase known from the literature). The UBVR colours of none of them give indication on the presence of an elliptical galaxy which, according to conventional concepts, must encompass a variable nonthermal source. 5) Two blue objects, 0548+165 and 0713+199, which are situated at low galactic latitudes (b2=-5 deg and +14 deg respectively) have shown colours unusual for lacertids. Appendices contain the results of theoretical calculations of (U-B), (B-V) and (V-R) colours for purely power-law spectra F(ν)=constxνsup(α) with α in the range (-6.5-+2.5) and the results of UBV photometry of the BL Lac object OJ 287 during the years 1976-1982 (24 measurements)
[en] We stress the usefulness of the work reservoir in the formalism of thermodynamics, in particular in the context of the first law. To elucidate its usefulness, the formalism is then applied to the Joule expansion and other peculiar and instructive experimental situations, clarifying the concepts of configuration and dissipative work. The ideas and discussions presented in this study are primarily intended for undergraduate students, but they might also be useful to graduate students, researchers and teachers.
[en] The Feshbach-Kerman-Koonin (FKK) multi-step direct (MSD) theory of pre-equilibrium reactions has been used to compute the single-step cross-sections for some (p,α) reactions using the knock-on and pick-up reaction mechanisms at two incident proton energies. For the knock-on mechanism, the reaction was assumed to have taken place by the direct ejection of a preformed alpha cluster in a shell-model state of the target. But the reaction was assumed to have taken place by the pick-up of a preformed triton cluster (also bound in a shell-model state of the target core) by the incident proton for the pick-up mechanism. The Yukawa forms of potential were used for the proton-alpha (for the knock-on process) and proton-triton (for the pick-up process) interaction and several parameter sets for the proton and alpha-particle optical potentials. The calculated cross-sections for both mechanisms gave satisfactory fits to the experimental data. Furthermore, it has been shown that some combinations of the calculated distorted wave Born approximation cross-sections for the two reaction mechanisms in the FKK MSD theory are able to give better fits to the experimental data, especially in terms of range of agreement. In addition, the theory has been observed to be valid over a wider range of energy
[en] A request list for nuclear data which was produced from a computerized data file by the National Nuclear Data Center is presented. The request list is given by target nucleus (isotope) and then reaction type. The purpose of the compilation is to summarize the current needs of US Nuclear Energy programs and other applied technologies for nuclear data. Requesters are identified by laboratory, last name, and sponsoring US government agency
[en] An expression for the magnetopause reconnection power based on the dawn-dusk component of the reconnection electric field, that reduces to the substorm parameter epsilon for the limit that involves equal geomagnetic (B sub(G)) and magnetosheath (B sub(M)) magnetic field amplitudes at the magnetopause, is contrasted with the expression based on the whole reconnection electric field vector obtained by Gonzalez. The correlation examples of this report show that this (more general) expression for the reconnection power seems to correlate with the empirical dissipation parameter U sub(T) from Akasofu, with slightly better correlation coefficients than those obtained from similar correlations between the parameter epsilon and U sub(T). Thus, these (better) correlations show up for the more familiar values of the ratio B sub(G) / B sub(M) > 1. Nevertheless, the (expected) relatively small difference that seems to exist between these correlation coefficients suggests that, for practical purposes, the parameter epsilon could be used as well (instead of the more general expression) in similar correlation studies due to its impler format. On the other hand, studies that refer mainly to the difference in the magnitudes of epsilon and of the more general expression are expected to give results with less negligible differences. (Author)
[pt]Uma expressao para a forca de reconexao de magnetopausa baseada sobre a componente 'dawn-dusk' do campo eletrico de reconexao, que reduz o parametro de sub-tormenta epsilon para o limite que envolve iguais amplitudes de campos geomagneticos (B sub(G)) e bainhas magneticas (B sub(M)), e confrontada com a expressao baseada sobre o vetor de campo eletrico de reconexao completo obtido por Gonzalez. Os exemplos de correlacao desse anuncio mostra que essa expressao (mais geral) para a forca de reconexao parece correlacionar-se com o parametro de dissipacao empirico U sub(T) de Akasofu, com coeficientes de correlacao um pouco melhores do que aqueles obtidos de correlacoes similares entre o parametro epsilon e U sub(T). Assim, essas correlacoes (melhores) melhoram para os valores mais familiares da razao B sub(G) / B sub(M) > 1. Contudo, a relativamente pequena diferenca (esperada) que parece existir entre esses coeficientes de correlacao sugere que, para efeitos praticos, o parametro epsilon possa ser usado tambem (ao inves da expressao mais geral) em estudos de correlacao similares devido ao seu formato mais simples. Espera-se que por outro lado, estudos que se referem principalmente a diferenca nas magnitudes de epsilon e da expressao mais geral deem resultados com diferencas menos despreziveis. (L.C.)