21,565 research outputs found
An analytical method to predict efficiency of aircraft gearboxes
A spur gear efficiency prediction method previously developed by the authors was extended to include power loss of planetary gearsets. A friction coefficient model was developed for MIL-L-7808 oil based on disc machine data. This combined with the recent capability of predicting losses in spur gears of nonstandard proportions allows the calculation of power loss for complete aircraft gearboxes that utilize spur gears. The method was applied to the T56/501 turboprop gearbox and compared with measured test data. Bearing losses were calculated with large scale computer programs. Breakdowns of the gearbox losses point out areas for possible improvement
Winter wheat: A model for the simulation of growth and yield in winter wheat
The basic ideas and constructs for a general physical/physiological process level winter wheat simulation model are documented. It is a materials balance model which calculates daily increments of photosynthate production and respiratory losses in the crop canopy. The partitioning of the resulting dry matter to the active growing tissues in the plant each day, transpiration and the uptake of nitrogen from the soil profile are simulated. It incorporates the RHIZOS model which simulates, in two dimensions, the movement of water, roots, and soluble nutrients through the soil profile. It records the time of initiation of each of the plant organs. These phenological events are calculated from temperature functions with delays resulting from physiological stress. Stress is defined mathematically as an imbalance in the metabolite supply; demand ratio. Physiological stress is also the basis for the calculation of rates of tiller and floret abortion. Thus, tillering and head differentiation are modeled as the resulants of the two processes, morphogenesis and abortion, which may be occurring simulaneously
Recommended from our members
Justification bias in self-reported disability: New evidence from panel data
The relationship between health and work is frequently investigated using self-assessments of disability from social surveys. The complication is that respondents may overstate their level of disability to justify non-employment and welfare receipt. This study provides new evidence on the existence and magnitude of justification bias by exploiting a novel feature of a large longitudinal survey: each wave respondents are asked identical disability questions twice; near the beginning and end of the face-to-face interview. Prior to answering the second disability question, respondents are asked a series of questions that increase the salience of their employment and welfare circumstances. Justification bias is identified by comparing the variation between the two measures within-individuals over time, with the variation in employment status over time. Results indicate substantial and statistically significant justification bias; especially for men and women who receive disability pensions
Covariance, correlation and entanglement
Some new identities for quantum variance and covariance involving commutators
are presented, in which the density matrix and the operators are treated
symmetrically. A measure of entanglement is proposed for bipartite systems,
based on covariance. This works for two- and three-component systems but
produces ambiguities for multicomponent systems of composite dimension. Its
relationship to angular momentum dispersion for symmetric symmetric spin states
is described.Comment: 30 pages, Latex, to appear in J Phys
Black-holes, topological strings and large N phase transitions
The counting of microstates of BPS black-holes on local Calabi-Yau of the
form is explored
by computing the partition function of q-deformed Yang-Mills theory on .
We obtain, at finite , the instanton expansion of the gauge theory. It can
be written exactly as the partition function for U(N) Chern-Simons gauge theory
on a Lens space, summed over all non-trivial vacua, plus a tower of
non-perturbative instanton contributions. In the large limit we find a
peculiar phase structure in the model. At weak string coupling the theory
reduces to the trivial sector and the topological string partition function on
the resolved conifold is reproduced in this regime. At a certain critical
point, instantons are enhanced and the theory undergoes a phase transition into
a strong coupling regime. The transition from the strong coupling phase to the
weak coupling phase is of third order.Comment: 16 pages, 3 figures; Invited talk given at QG05, Cala Gonone (Italy),
September 200
Effects to Scalar Meson Decays of Strong Mixing between Low and High Mass Scalar Mesons
We analyze the mass spectroscopy of low and high mass scalar mesons and get
the result that the coupling strengths of the mixing between low and high mass
scalar mesons are very strong and the strengths of mixing for scalar
mesons and those of I=0 scalar mesons are almost same. Next, we analyze the
decay widths and decay ratios of these mesons and get the results that the
coupling constants for which represents the coupling of high
mass scalar meson -> two pseudoscalar mesons are almost same as the
coupling for the I=0. On the other hand, the coupling constant for
which represents the low mass scalar meson -> are far
from the coupling constant for I=0. We consider a resolution for this
discrepancy. Coupling constant for glueball -> is smaller than
the coupling . is .Comment: 15 pages, 6 figure
Mechanism for a next-to-lowest lying scalar meson nonet
Recent work suggests the existence of a non-conventional lowest-lying scalar
nonet containing the a0(980). Then the a0(1450) and also the K0*(1430) are
likely candidates to belong to a conventional p-wave nonet. However
a comparison of their properties with those expected on this basis reveals a
number of puzzling features. It is pointed out that these puzzles can be
resolved in a natural and robust way by assuming a ``bare'' conventional p-wave
scalar nonet to mix with a lighter four quark
scalar nonet to form new ``physical'' states. The essential mechanism is driven
by the fact that the isospinor is lighter than the isovector in the unmixed multiplet.Comment: 22 pages, 6 figure
Recommended from our members
Who provides inconsistent reports of their health status? The importance of age, cognitive ability and socioeconomic status
Self-assessed health (SAH) measures are widely used in models of health and health inequalities. Such models assume that SAH is a reliable measure of health status. We utilise a unique feature of a national longitudinal survey to examine the consistency of responses to a standard SAH question that is asked twice to the same individual in close temporal proximity in up to three waves (2001, 2009, and 2013). In particular, we analyse whether the consistency of responses varies with personal characteristics. The main analysis sample includes 18,834 individual-year observations. We find that 57% of respondents provide inconsistent reports at least once. Characteristics that are associated with significantly higher inconsistencies are age, education, cognitive ability, and time between responses. The results suggest that there are systematic differences in the ability of individuals' to self-evaluate and summarise their own health. Consequently, failure to account for such error may lead to large estimation biases in models of health outcomes, particularly with respect to the relationship between education, cognitive ability, and health
Sequence Analysis of HindIII Q2 Fragment of Capripoxvirus Reveals a Putative Gene Encoding a G-Protein-Coupled Chemokine Receptor Homologue
AbstractThe DNA sequence of the HindIII Q2 fragment near the left terminus of the capripoxvirus (KS-1 strain) genome was determined. The sequence contains two complete open reading frames (ORFs) and a part of a third. Analysis of the deduced amino acid sequence of one of these ORFs, Q2/3L, revealed that this gene has the capacity to encode a protein which is related to members of the G-protein coupled chemokine receptor subfamily, the swinepoxvirus K2R and the human cytomegalovirus US28 ORFs. It has the key structural characteristics of the G-protein-coupled receptor superfamily, e.g., seven hydrophobic regions, predicted to span the cell membrane, and the cysteine residues in the first and second extracellular loops that are implicated in formation of a disulfide bond. Southern blot analysis showed that all three species of the Capripoxvirus genus, i.e., sheep pox, goat pox, and lumpy skin disease of cattle, contain copies of this putative G-proteincoupled chemokine receptor homologue
- …