1,758 research outputs found
Decision support for crew rostering at NS
This paper describes a method for solving the cyclic crew rostering problem (CCRP). This is the problem of cyclically ordering a set of duties for a number of crew members, such that several complex constraints are satisfied and such that the quality of the obtained roster is as high as possible. The described method was tested on a number of instances of NS, the largest operator of passenger trains in the Netherlands. These instances involve the generation of rosters for groups of train drivers or conductors of NS. The tests show that high quality solutions for practical instances of the CCRP can be generated in an acceptable amount of computing time. Finally, we describe an experiment where we constructed rosters in an automatic way for a group of conductors. They preferred our—generated—rosters over their own manually constructed rosters
Controlling the quality factor of a tuning-fork resonance between 9 K and 300 K for scanning-probe microscopy
We study the dynamic response of a mechanical quartz tuning fork in the
temperature range from 9 K to 300 K. Since the quality factor Q of the
resonance strongly depends on temperature, we implement a procedure to control
the quality factor of the resonance. We show that we are able to dynamically
change the quality factor and keep it constant over the whole temperature
range. This procedure is suitable for applications in scanning probe
microscopy.Comment: 5 pages, 6 figure
(Meta-)stable reconstructions of the diamond(111) surface: interplay between diamond- and graphite-like bonding
Off-lattice Grand Canonical Monte Carlo simulations of the clean diamond
(111) surface, based on the effective many-body Brenner potential, yield the
Pandey reconstruction in agreement with \emph{ab-initio}
calculations and predict the existence of new meta-stable states, very near in
energy, with all surface atoms in three-fold graphite-like bonding. We believe
that the long-standing debate on the structural and electronic properties of
this surface could be solved by considering this type of carbon-specific
configurations.Comment: 4 pages + 4 figures, Phys. Rev. B Rapid Comm., in press (15Apr00).
For many additional details (animations, xyz files) see electronic supplement
to this paper at http://www.sci.kun.nl/tvs/carbon/meta.htm
Collineation group as a subgroup of the symmetric group
Let be the projectivization (i.e., the set of one-dimensional vector
subspaces) of a vector space of dimension over a field. Let be a
closed (in the pointwise convergence topology) subgroup of the permutation
group of the set . Suppose that contains the
projective group and an arbitrary self-bijection of transforming a
triple of collinear points to a non-collinear triple. It is well-known from
\cite{KantorMcDonough} that if is finite then contains the
alternating subgroup of .
We show in Theorem \ref{density} below that , if
is infinite.Comment: 9 page
Extraction of optical Bloch modes in a photonic-crystal waveguide
We perform phase-sensitive near-field scanning optical microscopy on
photonic-crystal waveguides. The observed intricate field patterns are analyzed
by spatial Fourier transformations, revealing several guided TE- and TM-like
modes. Using the reconstruction algorithm proposed by Ha, et al. (Opt. Lett. 34
(2009)), we decompose the measured two-dimensional field pattern in a
superposition of propagating Bloch modes. This opens new possibilities to study
specific modes in near-field measurements. We apply the method to study the
transverse behavior of a guided TE-like mode, where the mode extends deeper in
the surrounding photonic crystal when the band edge is approached
Vermogensdelicten en onveiligheid op het werk: de klok luiden of niet?
Achtergrond: Wanneer een werknemers erachter komt dat een collega geld of goederen verduistert, zal niet iedereen in zijn of haar plaats direct aan de bel trekken. Begrijpelijk, want met veel klokkenluiders in Nederland loopt het slecht af. Mede hierdoor komen misstanden vaak niet aan het licht. Doel: De studie onderzoekt in welke situaties medewerkers wel zouden melden, bij wie zij dat het liefst zouden doen en of zij ook extern zouden melden indien een interne melding geen effect heeft. Methode: In dit onderzoek hebben 122 werknemers vier vignetten gelezen van verschillende aard en ernst (verduistering en onveiligheid). Aan hen is gevraagd of zij intern en/of extern zouden melden, zo ja, bij wie en of zij ook behoefte hebben aan anonimiteit. Tevens is gevraagd naar de motieven om wel of niet te melden. Resultaten: Interessant zijn vooral de gevonden verschillen tussen de vier vormen van misstanden. Zo zouden werknemers bij ernstige verduistering vaker naar een vertrouwenspersoon toestappen, terwijl bij lichte verduistering meestal aan de direct leidinggevende gedacht wordt. Verder zien werknemers vaak af van extern melden, omdat zij vinden dat de misstand een interne zaak is en de goede naam van het bedrijf kan worden geschaad. Deze loyaliteit geldt ook bij de meer ernstige misstanden. Conclusie: Indien direct leidinggevenden een open houding aannemen, kunnen misstanden wellicht vaker in de kiem worden gesmoord. Tevens is het raadzaam om een klokkenluidersregeling zodanig in te richten dat deze voldoende flexibel is om aan te kunnen sluiten op de specifieke omstandigheden van het geval
Manifesto for Digital Social Touch in Crisis
This qualitative exploratory research paper presents a Manifesto for Digital Social Touch in Crisis - a provocative call to action to designers, developers and researchers to rethink and reimagine social touch through a deeper engagement with the social and sensory aspects of touch. This call is motivated by concerns that social touch is in a crisis signaled by a decline in social touch over the past 2 decades, the problematics of inappropriate social touch, and the well documented impact of a lack of social touch on communication, relationships, and well-being and health. These concerns shape how social touch enters the digital realm and raise questions for how and when the complex space of social touch is mediated by technologies, as well the societal implications. The paper situates the manifesto in the key challenges facing haptic designers and developers identified through a series of interdisciplinary collaborative workshops with participants from computer science, design, engineering, HCI and social science from both within industry and academia, and the research literature on haptics. The features and purpose of the manifesto form are described, along with our rationale for its use, and the method of the manifesto development. The starting points, opportunities and challenges, dominant themes and tensions that shaped the manifesto statements are then elaborated on. The paper shows the potential of the manifesto form to bridge between HCI, computer science and engineers, and social scientists on the topic of social touch
Sensitivity of the Atlantic meridional overturning circulation to South Atlantic freshwater anomalies
The sensitivity of the Atlantic Meridional Overturning Circulation (AMOC) to changes in basin integrated net evaporation is highly dependent on the zonal salinity contrast at the southern border of the Atlantic. Biases in the freshwater budget strongly affect the stability of the AMOC in numerical models. The impact of these biases is investigated, by adding local anomaly patterns in the South Atlantic to the freshwater fluxes at the surface. These anomalies impact the freshwater and salt transport by the different components of the ocean circulation, in particular the basin-scale salt-advection feedback, completely changing the response of the AMOC to arbitrary perturbations. It is found that an appropriate dipole anomaly pattern at the southern border of the Atlantic Ocean can collapse the AMOC entirely even without a further hosing. The results suggest a new view on the stability of the AMOC, controlled by processes in the South Atlantic. <br/
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