98,297 research outputs found
Initiation and Propagation of Transverse Cracking in Composite Laminates
The matrix cracking transverse to loading direction is usually the one of most
common observations of damages in composite laminates. The initiation and
propagation of transverse cracks have been a longstanding issue in the last few
decades. In this paper, a three-dimensional stress analysis method based on the state
space approach is used to compute the stresses, including the inter-laminar stresses
near transverse cracks in laminated composites. The stress field is then used to
estimate the energy release rate, from which the initiation and propagation of
transverse cracking are predicted. The proposed method is illustrated by numerical
solutions and is validated by available experimental results. To the best knowledge of
the authors, the predictions of crack behaviour for non-symmetrical laminates and
laminates subject to in-plane shearing are presented for the first time in the literature
Can life survive Gamma-Ray Bursts in the high-redshift universe?
Nearby Gamma-Ray Bursts (GRBs) have been proposed as a possible cause of mass
extinctions on Earth. Due to the higher event rate of GRBs at higher redshifts,
it has been speculated that life as we know it may not survive above a certain
redshift (e.g. ). We examine the duty cycle of lethal (life-threatening)
GRBs in the solar neighborhood, in the Sloan Digital Sky Survey (SDSS) galaxies
and GRB host galaxies, with the dependence of the long GRB rate on star
formation and metallicity properly taken into account. We find that the number
of lethal GRBs attacking Earth within the past 500 Myr ( epoch of the
Ordovician mass extinction) is . The number of lethal GRBs hitting a
certain planet increases with redshift, thanks to the increasing star formation
rate and decreasing metallicity in high- galaxies. Taking 1 per 500 Myr as a
conservative duty cycle for life to survive, as evidenced by our existence, we
find that there are still a good fraction of SDSS galaxies beyond where
the GRB rate at half-mass radius is lower than this value. We derive the
fraction of such benign galaxies as a function of redshift through Monte Carlo
simulations, and find that the fraction is at and even at . The mass distribution of benign galaxies is dominated
by Milky-Way-like ones, thanks to their commonness, relatively large mass, and
low star formation rate. GRB host galaxies are among the most dangerous ones.Comment: Accepted for publication in The Astrophysical Journal, 7 pages, 4
figures, 1 tabl
How Do Organizations Assess for Potential, in addition to a Talent Review Process?
Demand for high potential talent has increased dramatically in the past five years as companies have struggled to fill vacancies due to a competitive talent market. Therefore, having a strong talent pipeline is extremely critical to organizations. Most companies evaluate high potential talent based on three criteria: engagement, ability, aspiration to hold successive leadership. But only 53% of organizations are confident in their ability to select and assess the best talent. An efficient tool is necessary to assess and capture the best talent in the organization. These four categories of tools are widely used by industries and have been considered successful and effective when measuring potential leaders: Assessment and development centers External assessment tools Company self-developed assessment methods 360-degree employee feedback assessment
To better understand the benefits of using these tools, this summary report will analyze the essence of the tools and provide case studies of top performers in the industry using these methods
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