28,951 research outputs found
Forecasting for Marketing
Research on forecasting is extensive and includes many studies that have tested alternative methods in order to determine which ones are most effective. We review this evidence in order to provide guidelines for forecasting for marketing. The coverage includes intentions, Delphi, role playing, conjoint analysis, judgmental bootstrapping, analogies, extrapolation, rule-based forecasting, expert systems, and econometric methods. We discuss research about which methods are most appropriate to forecast market size, actions of decision makers, market share, sales, and financial outcomes. In general, there is a need for statistical methods that incorporate the manager's domain knowledge. This includes rule-based forecasting, expert systems, and econometric methods. We describe how to choose a forecasting method and provide guidelines for the effective use of forecasts including such procedures as scenarios.forecasting, marketing
Forecasting Methods for Marketing:* Review of Empirical Research
This paper reviews the empirical research on forecasting in marketing. In addition, it presents results from some small scale surveys. We offer a framework for discussing forecasts in the area of marketing, and then review the literature in light of that framework. Particular emphasis is given to a pragmatic interpretation of the literature and findings. Suggestions are made on what research is needed.forecasting, marketing, methods, review, research
Detailed studies of aviation fuel flowability
Six Jet A fuels, with varying compositions, were tested for low temperature flowability in a 190-liter simulator tank that modeled a section of a wing tank of a wide-body commercial airplane. The insulated tank was chilled by circulating coolant through the upper and lower surfaces. Flow-ability was determined as a function of fuel temperature by holdup, the fraction of unflowable fuel remaining in the tank after otherwise complete withdrawal. In static tests with subfreezing tank conditions, hold up varied with temperature and fuel composition. However, a general correlation of two or three classes of fuel type was obtained by plotting holdup as a function of the difference between freezing point and boundary-layer temperature, measured 0.6 cm above the bottom tank surface. Dynamic conditions of vibrations and slosh or rate of fuel withdrawal had very minor effects on holdup. Tests with cooling schedules to represent extreme, cold-day flights showed, at most, slight holdup for any combination of fuel type or dynamic conditions. Tests that superimposed external fuel heating and recirculation during the cooldown period indicates reduced hold up by modification of the low-temperature boundary layer. Fuel heating was just as effective when initiated during the later times of the tests as when applied continuously
Effects of Extreme Obliquity Variations on the Habitability of Exoplanets
We explore the impact of obliquity variations on planetary habitability in
hypothetical systems with high mutual inclination. We show that large
amplitude, high frequency obliquity oscillations on Earth-like exoplanets can
suppress the ice-albedo feedback, increasing the outer edge of the habitable
zone. We restrict our exploration to hypothetical systems consisting of a
solar-mass star, an Earth-mass planet at 1 AU, and 1 or 2 larger planets. We
verify that these systems are stable for years with N-body simulations,
and calculate the obliquity variations induced by the orbital evolution of the
Earth-mass planet and a torque from the host star. We run a simplified energy
balance model on the terrestrial planet to assess surface temperature and ice
coverage on the planet's surface, and we calculate differences in the outer
edge of the habitable zone for planets with rapid obliquity variations. For
each hypothetical system, we calculate the outer edge of habitability for two
conditions: 1) the full evolution of the planetary spin and orbit, and 2) the
eccentricity and obliquity fixed at their average values. We recover previous
results that higher values of fixed obliquity and eccentricity expand the
habitable zone, but also find that obliquity oscillations further expand
habitable orbits in all cases. Terrestrial planets near the outer edge of the
habitable zone may be more likely to support life in systems that induce rapid
obliquity oscillations as opposed to fixed-spin planets. Such planets may be
the easiest to directly characterize with space-borne telescopes.Comment: 46 pages, 12 Figures, 5 Table
Bound States and Universality in Layers of Cold Polar Molecules
The recent experimental realization of cold polar molecules in the rotational
and vibrational ground state opens the door to the study of a wealth of
phenomena involving long-range interactions. By applying an optical lattice to
a gas of cold polar molecules one can create a layered system of planar traps.
Due to the long-range dipole-dipole interaction one expects a rich structure of
bound complexes in this geometry. We study the bilayer case and determine the
two-body bound state properties as a function of the interaction strength. The
results clearly show that a least one bound state will always be present in the
system. In addition, bound states at zero energy show universal behavior and
extend to very large radii. These results suggest that non-trivial bound
complexes of more than two particles are likely in the bilayer and in more
complicated chain structures in multi-layer systems.Comment: 6 pages, 5 figures. Revised version to be publishe
Weakly bound states of polar molecules in bilayers
We investigate a system of two polarized molecules in a layered trap. The
molecules reside in adjacent layers and interact purely via the dipole-dipole
interaction. We determine the properties of the ground state of the system as a
function of the dipole moment and polarization angle. A bound state is always
present in the system and in the weak binding limit the bound state extends to
a very large distance and shows universal behavior.Comment: Presented at the 21st European Conference on Few-Body Problems in
Physics, Salamanca, Spain, 30 August - 3 September 201
Elimination of Clock Jitter Noise in Spaceborn Laser Interferometers
Space gravitational wave detectors employing laser interferometry between
free-flying spacecraft differ in many ways from their laboratory counterparts.
Among these differences is the fact that, in space, the end-masses will be
moving relative to each other. This creates a problem by inducing a Doppler
shift between the incoming and outgoing frequencies. The resulting beat
frequency is so high that its phase cannot be read to sufficient accuracy when
referenced to state-of-the-art space-qualified clocks. This is the problem that
is addressed in this paper. We introduce a set of time-domain algorithms in
which the effects of clock jitter are exactly canceled. The method employs the
two-color laser approach that has been previously proposed, but avoids the
singularities that arise in the previous frequency-domain algorithms. In
addition, several practical aspects of the laser and clock noise cancellation
schemes are addressed.Comment: 20 pages, 5 figure
A Solvable Model for Decoupling of Interacting Clusters
We consider M clusters of interacting particles, whose in-group interactions
are arbitrary, and inter-group interactions are approximated by oscillator
potentials. We show that there are masses and frequencies that decouple the
in-group and inter-group degrees of freedom, which reduces the initial problem
to M independent problems that describe each of the relative in-group systems.
The dynamics of the M center-of-mass coordinates is described by the
analytically solvable problem of M coupled harmonic oscillators. This paper
derives and discusses these decoupling conditions. Furthermore, to illustrate
our findings, we consider a charged impurity interacting with a ring of ions.
We argue that the impurity can be used to probe the center-of-mass dynamics of
the ions.Comment: Version accepted for publication in EP
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