5,738 research outputs found
A cost benefit analysis of employee assistance programs and health promotion programs
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references: leaves 10-11.For many years business has been searching for ways to make companies more profitable. Some programs that many businesses have implemented in order to increase profits are Employee Assistance Programs (EAPs) and Health Promotion Programs (HPPs). Employee Assistance Programs offer a wide range of services including marriage counseling, parent education classes, and legal advice. Health Promotion Programs offer wellness services and focus on preventative measures to bring health costs down. A meta-analysis will be conducted to determine if a cost offset effect occurs due to the utilization of these programs. After collecting 20 articles for review the present study has found that a general reading of the studies seem to suggest a common, positive cost benefit for EAPs/HPPs
Magnetohydrodynamics of the Weakly Ionized Solar Photosphere
We investigate the importance of ambipolar diffusion and Hall currents for
high-resolution comprehensive ('realistic') photospheric simulations. To do so
we extended the radiative magnetohydrodynamics code \emph{MURaM} to use the
generalized Ohm's law under the assumption of local thermodynamic equilibrium.
We present test cases comparing analytical solutions with numerical simulations
for validation of the code. Furthermore, we carried out a number of numerical
experiments to investigate the impact of these neutral-ion effects in the
photosphere. We find that, at the spatial resolutions currently used (5-20 km
per grid point), the Hall currents and ambipolar diffusion begin to become
significant -- with flows of 100 m/s in sunspot light bridges, and changes of a
few percent in the thermodynamic structure of quiet-Sun magnetic features. The
magnitude of the effects is expected to increase rapidly as smaller-scale
variations are resolved by the simulations.Comment: accepted Ap
Mesoscopic study on historic masonry
This paper presents a comprehensive approach to the evaluation of macroscopic
material parameters for natural stone and quarry masonry. To that end, a
reliable non-linear material model on a meso-scale is developed to cover the
random arrangement of stone blocks and quasi-brittle behaviour of both basic
components, as well as the impaired cohesion and tensile strength on the
interface between the blocks and mortar joints. The paper thus interrelates the
following three problems: (i) definition of a suitable periodic unit cell (PUC)
representing a particular masonry structure; (ii) derivation of material
parameters of individual constituents either experimentally or running a mixed
numerical-experimental problem; (iii) assessment of the macroscopic material
parameters including the tensile and compressive strengths and fracture energy.Comment: 38 pages, 15 figure
The stellar atmosphere simulation code Bifrost
Context: Numerical simulations of stellar convection and photospheres have
been developed to the point where detailed shapes of observed spectral lines
can be explained. Stellar atmospheres are very complex, and very different
physical regimes are present in the convection zone, photosphere, chromosphere,
transition region and corona. To understand the details of the atmosphere it is
necessary to simulate the whole atmosphere since the different layers interact
strongly. These physical regimes are very diverse and it takes a highly
efficient massively parallel numerical code to solve the associated equations.
Aims: The design, implementation and validation of the massively parallel
numerical code Bifrost for simulating stellar atmospheres from the convection
zone to the corona.
Methods: The code is subjected to a number of validation tests, among them
the Sod shock tube test, the Orzag-Tang colliding shock test, boundary
condition tests and tests of how the code treats magnetic field advection,
chromospheric radiation, radiative transfer in an isothermal scattering
atmosphere, hydrogen ionization and thermal conduction.
Results: Bifrost completes the tests with good results and shows near linear
efficiency scaling to thousands of computing cores
On red shifs in the transition region and corona
We present evidence that transition region red-shifts are naturally produced
in episodically heated models where the average volumetric heating scale height
lies between that of the chromospheric pressure scale height of 200 km and the
coronal scale height of 50 Mm. In order to do so we present results from 3d MHD
models spanning the upper convection zone up to the corona, 15 Mm above the
photosphere. Transition region and coronal heating in these models is due both
the stressing of the magnetic field by photospheric and convection `zone
dynamics, but also in some models by the injection of emerging magnetic flux.Comment: 8 pages, 9 figures, NSO Workshop #25 Chromospheric Structure and
Dynamic
The green corona data: 1947-1976, revisited
Re-examining a continuous monthly data set for the
green-line corona brightness, covering February 1947 to September 1976, we have found that practically no delay exists between the trends of the green-line coronal intensity in the equatorial and middle-latitude belts at the beginning of solar activity cycle No. 20, while a
previous cycle (No. 19) shows a sudden increase in the corona intensity brightness at middle latitudes followed by a delayed one at the equatorial belts, supporting recent
findings on even-odd solar cycle differences observed in the half-yearly green corona database (1943-1993). The north-south asymmetry in the hemispheric solar activity is
not involved in this phenomenon
Linear response within the projection-based renormalization method: Many-body corrections beyond the random phase approximation
The explicit evaluation of linear response coefficients for interacting
many-particle systems still poses a considerable challenge to theoreticians. In
this work we use a novel many-particle renormalization technique, the so-called
projector-based renormalization method, to show how such coefficients can
systematically be evaluated. To demonstrate the prospects and power of our
approach we consider the dynamical wave-vector dependent spin susceptibility of
the two-dimensional Hubbard model and also determine the subsequent magnetic
phase diagram close to half-filling. We show that the superior treatment of
(Coulomb) correlation and fluctuation effects within the projector-based
renormalization method significantly improves the standard random phase
approximation results.Comment: 17 pages, 7 figures, revised versio
Decision Support Systems for Sustainable Logistics: A Review and Bibliometric Analysis
Purpose: Decision-making in logistics is an increasingly complex task for organizations as these involve decisions at strategic, tactical and operational levels coupled with the triple bottom line (TBL) of sustainability. Decision support systems (DSS) played a vital role in arguably solving the challenges associated with decision making in sustainable logistics. This review is a systematic attempt to explore the current state of the research in the domain of DSS for logistics while considering sustainability aspects. Design/methodology/approach: A systematic review approach using a set of relevant keywords with several exclusion criteria was adopted to identify literature related to DSS for sustainable logistics. A total of 40 papers were found from 1994 to 2015, which were then analysed along the dimensions of publishing trend, geographic distribution and collaboration, the most influential journals, affiliations and authors as well as the key themes of identified literature. The analysis was conducted by means of bibliometric and text mapping tools, namely BibExcel, gpsvisualizer, and VOSviewer. Findings: The bibliometric analysis showed that DSS for sustainable logistics is an emerging field; however, it is still evolving but at a slower pace. Furthermore, most of the contributing affiliations belong to the United States and the United Kingdom. The text mining and keyword analysis revealed key themes of identified papers. The inherent key themes were decision models and frameworks to address sustainable logistics issues covering transport, distribution and third party logistics. The most prominent sustainable logistics issue was carbon footprinting. Social impact has been given less attention in comparison to economic and environmental aspects. The literature has adequate room for proposing more effective solutions by considering various types of MCDA (multi-criteria decision analysis) methods and DSS configurations while simultaneously considering economic, environmental and social aspects of sustainable logistics. Moreover, the field has potential to include logistics from wide application areas including freight transport through road, rail, sea, air as well as inter-modal transport, port operations, material handling and warehousing. Originality/value: To the best of the authors’ knowledge, this is the first systematic review of DSS for sustainable logistics using bibliometric and text analysis. The key themes and research gaps identified in this paper will provide a reference point that will encourage and guide interested researchers for future study, thus aiding both theoretical and practical advancements in this discipline
Twisted flux tube emergence from the convection zone to the corona
3D numerical simulations of a horizontal magnetic flux tube emergence with
different twist are carried out in a computational domain spanning the upper
layers of the convection zone to the lower corona. We use the Oslo Staggered
Code to solve the full MHD equations with non-grey and non-LTE radiative
transfer and thermal conduction along the magnetic field lines. The emergence
of the magnetic flux tube input at the bottom boundary into a weakly magnetized
atmosphere is presented. The photospheric and chromospheric response is
described with magnetograms, synthetic images and velocity field distributions.
The emergence of a magnetic flux tube into such an atmosphere results in varied
atmospheric responses. In the photosphere the granular size increases when the
flux tube approaches from below. In the convective overshoot region some 200km
above the photosphere adiabatic expansion produces cooling, darker regions with
the structure of granulation cells. We also find collapsed granulation in the
boundaries of the rising flux tube. Once the flux tube has crossed the
photosphere, bright points related with concentrated magnetic field, vorticity,
high vertical velocities and heating by compressed material are found at
heights up to 500km above the photosphere. At greater heights in the magnetized
chromosphere, the rising flux tube produces a cool, magnetized bubble that
tends to expel the usual chromospheric oscillations. In addition the rising
flux tube dramatically increases the chromospheric scale height, pushing the
transition region and corona aside such that the chromosphere extends up to 6Mm
above the photosphere. The emergence of magnetic flux tubes through the
photosphere to the lower corona is a relatively slow process, taking of order 1
hour.Comment: 53 pages,79 figures, Submitted to Ap
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