1,925 research outputs found
Quality related communication approaches for organic food
As food quality becomes more complex, consumer s are tending to reduce their involvement in the food purchase decision- making process. Consequently, prices are becoming more significant as they represent an easy choice criterion when consumer s have less information about the differences between the product and process quality inherent in food items (including environmental or social issues). The organic food sector provides high, complex food quality profiles and has therefore been seriously affected by this development. Consequently some SMEs in the food business sector are starting to emphasize certain quality factors, such as sustainable production and processing, as a means of communicating their added value to consumer s. Based on published scientific and unpublished literature, this paper provides an overview of the main instrument s and media of communication on food quality, illustrated by case studies. It also present s the results of a test by means of an information display matrix, conducted in order to analyse the consumer information and quality assessment behaviour involved in apple purchase in Switzerland. Keywords food quality, food indicators, means of communication, food miles, social standards, consumer behaviour.Marketing,
Development of an internal restraint system for an integrated restraint-pressure suit system Report, 7 Jun. 1965 - 28 Jun. 1966
Internal restraint system, composed of liquid filled garment and separate auxiliary system, for integrated restraint pressure suit for acceleration protection and thermal transpor
Sensitivity of Mission Energy Consumption to Turboelectric Distributed Propulsion Design Assumptions on the N3-X Hybrid Wing Body Aircraft
In a previous study by the authors it was shown that the N3-X, a 300 passenger hybrid wing body (HWB) aircraft with a turboelectric distributed propulsion (TeDP) system, was able to meet the NASA Subsonic Fixed Wing (SFW) project goal for N+3 generation aircraft of at least a 60% reduction in total energy consumption as compared to the best in class current generation aircraft. This previous study combined technology assumptions that represented the highest anticipated values that could be matured to technology readiness level (TRL) 4-6 by 2030. This paper presents the results of a sensitivity analysis of the total mission energy consumption to reductions in each key technology assumption. Of the parameters examined, the mission total energy consumption was most sensitive to changes to total pressure loss in the propulsor inlet. The baseline inlet internal pressure loss is assumed to be an optimistic 0.5%. An inlet pressure loss of 3% increases the total energy consumption 9%. However changes to reduce inlet pressure loss can result in additional distortion to the fan which can reduce fan efficiency or vice versa. It is very important that the inlet and fan be analyzed and optimized as a single unit. The turboshaft hot section is assumed to be made of ceramic matrix composite (CMC) with a 3000 F maximum material temperature. Reducing the maximum material temperature to 2700 F increases the mission energy consumption by only 1.5%. Thus achieving a 3000 F temperature in CMCs is important but not central to achieving the energy consumption objective of the N3-X/TeDP. A key parameter in the efficiency of superconducting motors and generators is the size of the superconducting filaments in the stator. The size of the superconducting filaments in the baseline model is assumed to be 10 microns. A 40 micron filament, which represents current technology, results in a 200% increase in AC losses in the motor and generator stators. This analysis shows that for a system with 40 micron filaments the higher stator losses plus the added weight and power of larger cryocoolers results in a 4% increase in mission energy consumption. If liquid hydrogen is used to cool the superconductors the 40 micron fibers results in a 200% increase in hydrogen required for cooling. Each pound of hydrogen used as fuel displaces 3 pounds of jet fuel. For the N3-X on the reference mission the additional hydrogen due to the increase stator losses reduces the total fuel weight 10%. The lighter fuel load and attendant vehicle resizing reduces the total energy consumption more than the higher stator losses increase it. As a result with hydrogen cooling there is a slight reduction in mission energy consumption with increasing stator losses. This counter intuitive result highlights the need to consider the full system impact of changes rather than just at the component or subsystem level
Construction of some missing eigenvectors of the XYZ spin chain at the discrete coupling constants and the exponentially large spectral degeneracy of the transfer matrix
We discuss an algebraic method for constructing eigenvectors of the transfer
matrix of the eight vertex model at the discrete coupling parameters. We
consider the algebraic Bethe ansatz of the elliptic quantum group for the case where the parameter satisfies for arbitrary integers , and . When or
is odd, the eigenvectors thus obtained have not been discussed previously.
Furthermore, we construct a family of degenerate eigenvectors of the XYZ spin
chain, some of which are shown to be related to the loop algebra
symmetry of the XXZ spin chain. We show that the dimension of some degenerate
eigenspace of the XYZ spin chain on sites is given by , if
is an even integer. The construction of eigenvectors of the transfer matrices
of some related IRF models is also discussed.Comment: 19 pages, no figure (revisd version with three appendices
Unusual magnetic properties of the low-dimensional quantum magnet Na2V3O7
We report the results of low-temperature measurements of the specific heat
Cp(T), ac susceptibility chi(T) and 23Na nuclear magnetic resonance NMR of
Na2V3O7. At liquid He temperatures Cp(T)/T exhibits broad field-dependent
maxima, which shift to higher temperatures upon increasing the applied magnetic
field H. Below 1.5 K the ac magnetic susceptibility chi(T) follows a
Curie-Weiss law and exhibits a cusp at 0.086 mK which indicates a phase
transition at very low temperatures. These results support the previous
conjecture that Na2V3O7 is close to a quantum critical point (QCP) at mu_{0}H =
0 T. The entire data set, including results of measurements of the NMR
spin-lattice relaxation 1/T1(T), reveals a complex magnetic behavior at low
temperatures. We argue that it is due to a distribution of singlet-triplet
energy gaps of dimerized V moments. The dimerization process evolves over a
rather broad temperature range around and below 100 K. At the lowest
temperatures the magnetic properties are dominated by the response of only a
minor fraction of the V moments.Comment: 10.5 pages, 15 figures. Submitted to Phys. Rev.
Cosmology with decaying tachyon matter
We investigate the case of a homogeneous tachyon field coupled to gravity in
a spatially flat Friedman-Robertson-Walker spacetime. Assuming the field
evolution to be exponentially decaying with time we solve the field equations
and show that, under certain conditions, the scale factor represents an
accelerating universe, following a phase of decelerated expansion. We make use
of a model of dark energy (with p=-\rho) and dark matter (p=0) where a single
scalar field (tachyon) governs the dynamics of both the dark components. We
show that this model fits the current supernova data as well as the canonical
\LambdaCDM model. We give the bounds on the parameters allowed by the current
data.Comment: 14 pages, 6 figures, v2, Discussions and references addede
Non-equilibrium Goldstone phenomenon in tachyonic preheating
The dominance of the direct production of elementary Goldstone waves is
demonstrated in tachyonic preheating by numerically determining the evolution
of the dispersion relation, the equation of state and the kinetic power spectra
for the angular degree of freedom of the complex matter field. The importance
of the domain structure in the order parameter distribution for the
quantitative understanding of the excitation mechanism is emphasized. Evidence
is presented for the very early decoupling of the low-momentum Goldstone modes.Comment: 14 LaTeX pages, 5 figures, version published in Phys. Rev.
Reheating After Quintessential Inflation and Gravitational Waves
We investigate the dependence of the gravitational wave spectrum from
quintessential inflation on the reheating process. We consider two extreme
reheating processes. One is the gravitational reheating by particle creation in
the expanding universe in which the beginning of the radiation dominated epoch
is delayed due to the presence of the epoch of domination of the kinetic energy
of the inflaton (kination). The other is the instant preheating considered by
Felder et al. in which the Universe becomes radiation dominated soon after the
end of inflation. We find that the spectrum of the gravitational waves at MHz is quite sensitive to the reheating process. This result is not
limited to quintessential inflation but applicable to various inflation models.
Conversely, the detection or non-detection of primordial gravitational waves at
100 MHz would provide useful information regarding the reheating process
in inflation.Comment: 15 pages, 5 figures, to be published in CQ
Operator realization of the SU(2) WZNW model
Decoupling the chiral dynamics in the canonical approach to the WZNW model
requires an extended phase space that includes left and right monodromy
variables. Earlier work on the subject, which traced back the quantum qroup
symmetry of the model to the Lie-Poisson symmetry of the chiral symplectic
form, left some open questions: - How to reconcile the monodromy invariance of
the local 2D group valued field (i.e., equality of the left and right
monodromies) with the fact that the latter obey different exchange relations? -
What is the status of the quantum group symmetry in the 2D theory in which the
chiral fields commute? - Is there a consistent operator formalism in the chiral
and in the extended 2D theory in the continuum limit? We propose a constructive
affirmative answer to these questions for G=SU(2) by presenting the chiral
quantum fields as sums of chiral vertex operators and q-Bose creation and
annihilation operators.Comment: 18 pages, LATE
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