940 research outputs found
Dwell Sensitivity Behavior and Modeling
Since engineering materials are exposed to dwell-times in service, it is important to understand the effects of dwell times on the fatigue life. The mechanisms controlling deformation and failure under dwell conditions are in terms of metallographic damage namely; transgranular fracture, intergranular fracture, mixed intergranular transgranular fracture modes, surface striated damage, creep damage and oxidation. These mechanisms are very difficult to include in a quantitative model to predict the dwell sensitivity behavior of high temperature materials. Published creep-fatigue data were compiled from various sources for a number of materials such as copper alloys (NARloy-Z, AMZ1RC), steel alloys (9Cr-lMo), and nickel based alloys(lN 100, Rene 95, Waspaloy). In general, dwell-times were found to be detrimental to the fatigue life of materials, but the exact extent of the effect varies depending on the material, duration of the dwell, and the direction in which a dwell was applied. In this research an attempt has been made to further develop the models of the senior author and include such concepts as stress relaxation with respect to a particular dwell time. Very limited data sets are available in the literature showing all the test details needed for developing a model for this research. However, the initial trials show stress relaxation as a result of a dwell cycle may exhibit an effect that may describe dwell. A dwell sensitivity damage mechanistic map and a new dwell sensitivity damage parameter were developed
Urban Settlement: Data, Measures, and Trends
This paper examines data on urbanization. We review the most commonly used data sources and highlight the difficulties inherent in defining and measuring the size of urban versus rural populations. We show that differences in the measurement of urban populations across countries and over time are significant and discuss the methods used for these measurements, as well as for projecting urbanization. We also analyze recent trends and patterns in urbanization. Finally, we describe the principal channels of urbanization and examine their relative contributions to the global urbanization process.urbanization, urbanization data
Urban Settlement: Data, Measures, and Trends
This paper examines data on urbanization. We review the most commonly used data sources, and highlight the difficulties inherent in defining and measuring the size of urban versus rural populations. We show that differences in the measurement of urban populations across countries and over time are significant, and discuss the methods used to obtain these measurements, as well as those for projecting urbanization. We also analyze recent trends and patterns in urbanization. Finally, we describe the principal channels of urbanization and examine their relative contributions to the global urbanization process.Urbanization, measurement, urban population
New frontiers in international strategy
This paper is based on a panel we organized at the "First Annual Conference on Emerging Research Frontiers in International Business Studies", organized by the Journal of International Business Studies (JIBS), to discuss several new lines of research in international strategy. Four lines of research are developed: The strategic implications of semiglobalization, the impact of institutional voids in international strategy, primitives and levels of analysis in international business, and strategies for the base of the pyramid. Taken together, these studies aim to open a new frontier in our understanding of International Strategy, based on the co-location of firms as places and a key element in international business.international business; semiglobalization; internal strategy; base pyramid; institutions; competitiveness;
Zero-field spin splitting in a two-dimensional electron gas with the spin-orbit interaction revisited
We consider a two-dimensional electron gas (2DEG) with the Rashba spin-orbit
interaction (SOI) in presence of a perpendicular magnetic field. We derive
analytical expressions of the density of states (DOS) of a 2DEG with the Rashba
SOI in presence of magnetic field by using the Green's function technique. The
DOS allows us to obtain the analytical expressions of the magnetoconductivities
for spin-up and spin-down electrons. The conductivities for spin-up and
spin-down electrons oscillate with different frequencies and gives rise to the
beating patterns in the amplitude of the Shubnikov de Hass (SdH) oscillations.
We find a simple equation which determines the zero-field spin splitting energy
if the magnetic field corresponding to any beat node is known from the
experiment. Our analytical results reproduce well the experimentally observed
non-periodic beating patterns, number of oscillations between two successive
nodes and the measured zero-field spin splitting energy.Comment: 5 pages, 2 figure
Distributing excess cash: the role of specially designated dividends
This study explores why firms distribute excess cash as specially designated dividends (SDDs) instead of using regular dividends or repurchasing shares. We survey top managers of NASDAQ, AMEX, and NYSE firms issuing at least one SDD between 1994 and 2001. The results show that firms tend to pay SDDs when they experience strong earnings and cash flows and want to increase at least temporarily the yield to shareholders. Having strong earnings and cash flows also provide an impetus for regular dividend increases, but paying regular dividends is part of a firm\u27s standard dividend policy. The primary motives for repurchasing shares are to take advantage of perceived market undervaluation of the firm\u27s shares and to improve performance measures, especially. Overall, the results lend support to the signaling explanation for the disbursement of excess funds, but not the free cash flow or wealth transfer explanations
Translation initiation factor eIF4G mediates in vitro poly(A) tail-dependent translation
Statistical Isotropy violation of the CMB brightness fluctuations
Certain anomalies at large angular scales in the cosmic microwave background
measured by WMAP have been suggested as possible evidence of breakdown of
statistical isotropy(SI). Most CMB photons free-stream to the present from the
surface of last scattering. It is thus reasonable to expect statistical
isotropy violation in the CMB photon distribution observed now to have
originated from SI violation in the baryon-photon fluid at last scattering, in
addition to anisotropy of the primordial power spectrum studied earlier in
literature.
We consider the generalized anisotropic brightness distribution fluctuations,
(at conformal time ) in contrast to the
SI case where it is simply a function of and . The brightness fluctuations expanded in Bipolar Spherical Harmonic
(BipoSH) series, can then be written as where terms encode deviations from statistical isotropy. We
study the evolution of from
non-zero terms at last
scattering. Similar to the SI case, power at small spherical harmonic (SH)
multipoles of at the last
scattering, is transferred to at
larger SH multipoles. The structural similarity is more apparent in the
asymptotic expression for large values of the final SH multipoles. This
formalism allows an elegant identification of any SI violation observed today
to a possible origin in the SI violation present in the baryon-photon fluid
(eg., due to the presence of significant magnetic field).Comment: 14 pages, 4 figures, added illustrative example of SI violation in
baryon-photon fluid, matches version accepted for publication in Phys. Rev.
Statistical isotropy of the Cosmic Microwave Background
The breakdown of statistical homogeneity and isotropy of cosmic perturbations
is a generic feature of ultra large scale structure of the cosmos, in
particular, of non trivial cosmic topology. The statistical isotropy (SI) of
the Cosmic Microwave Background temperature fluctuations (CMB anisotropy) is
sensitive to this breakdown on the largest scales comparable to, and even
beyond the cosmic horizon. We propose a set of measures,
() which for non-zero values indicate and quantify statistical
isotropy violations in a CMB map. We numerically compute the predicted
spectra for CMB anisotropy in flat torus universe models.
Characteristic signature of different models in the spectrum are
noted.Comment: Presented at PASCOS'03, January 3-8, 2003, in TIFR, Mumbai; to be
published in a special issue of 'Pramana' (4 pages, 1 figure, style files
included
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