12,406 research outputs found
Motor brush wear measured with strain gages
Balanced bridge circuit, supplied with low-voltage direct current and connected to a readout device, measures remaining brush material, rate of brush wear, armature runout, and brush signature
UV/IR symmetries of the -matrix and RG flow
The low energy -matrix which describes non-relativistic scattering arising
from finite-range forces has UV/IR symmetries that are hidden in the
corresponding effective field theory (EFT) action. It is shown that the
-matrix symmetries are manifest as geometric symmetries of the RG flow of
coupling constants in the EFT action in both three and two spatial dimensions.
An example is given demonstrating that UV/IR symmetry breaking in the
-matrix implies strong constraints on the RG flow of the coefficients of the
corresponding symmetry-breaking operators in the EFT.Comment: 15 pages, 4 figures. Examples and an appendix added in v
Multi-centre retrospective study of long-term outcomes following traumatic elbow luxation in 37 dogs
Surgery groups of the fundamental groups of hyperplane arrangement complements
Using a recent result of Bartels and Lueck (arXiv:0901.0442) we deduce that
the Farrell-Jones Fibered Isomorphism conjecture in L-theory is true for any
group which contains a finite index strongly poly-free normal subgroup, in
particular, for the Artin full braid groups. As a consequence we explicitly
compute the surgery groups of the Artin pure braid groups. This is obtained as
a corollary to a computation of the surgery groups of a more general class of
groups, namely for the fundamental group of the complement of any fiber-type
hyperplane arrangement in the complex n-space.Comment: 11 pages, AMSLATEX file, revised following referee's comments and
suggestions, to appear in Archiv der Mathemati
Automotive Stirling engine development program
The study of high power kinematic Stirling engines for transportation use, testing of Mod I and Mod II Stirling engines, and component development activities are summarized. Mod II development testing was performed to complete the development of the basic engine and begin characterization of performance. Mod I engines were used for Mod II component development and to obtain independent party (U.S. Air Force) evaluation of Stirling engine vehicle performance
Feasibility study for a Scanning Celestial Attitude Determination System /SCADS/ for three axis attitude determination at a Command and Data Acquisition /CDA/ station Final report
Scanning Celestial Attitude Determination System /SCADS/ for three axis attitude determination at Command and Data Acquisition /CDA/ statio
Trends Of Accounting Restatements During The Period 2000-2007 And Big Four/Five Auditors
The objective of this study is to provide further analysis on the trends of accounting restatements during the period 2000-07 and the role of Big four/five auditors. Given the changes in regulatory environment after the enforcement of Section 404 of the Sarbanes-Oxley Act, we find that there is a significant increase in restatements in recent years. We also find that restatements being disclosed in recent years are more serious, however, they are disclosed on a more timely basis. Consistent with the general belief that Big four/five auditors are better quality auditors, we find that they are associated with shorter restatement disclosure lags. In addition, restatements with positive financial statement effects are more likely to be disclosed sooner than those with negative effects
Toward precision Fermi liquid theory in flatland
The ultra-cold and weakly-coupled Fermi gas in two spatial dimensions is
studied in an effective field theory framework. Universal corrections to the
energy density are computed to three orders in the interaction strength with
special consideration given to the scale ambiguity associated with the
non-trivial renormalization of the singular contact interactions. The isotropic
superfluid gap is obtained to next-to-leading order, and nonuniversal
contributions to the energy density due to effective range effects, p-wave
interactions and three-body forces are computed. Results are compared with
precise Monte Carlo simulations of the energy density and the contact in the
weakly-coupled attractive and repulsive Fermi liquid regimes. In addition, the
known all-orders sum of ladder and ring diagrams is compared with Monte Carlo
simulations at weak coupling and beyond.Comment: 34 pages, 17 figure
The Impact of Shape on the Perception of Euler Diagrams
Euler diagrams are often used for visualizing data collected into sets. However, there is a significant lack of guidance regarding graphical choices for Euler diagram layout. To address this deficiency, this paper asks the question `does the shape of a closed curve affect a user's comprehension of an Euler diagram?' By empirical study, we establish that curve shape does indeed impact on understandability. Our analysis of performance data indicates that circles perform best, followed by squares, with ellipses and rectangles jointly performing worst. We conclude that, where possible, circles should be used to draw effective Euler diagrams. Further, the ability to discriminate curves from zones and the symmetry of the curve shapes is argued to be important. We utilize perceptual theory to explain these results. As a consequence of this research, improved diagram layout decisions can be made for Euler diagrams whether they are manually or automatically drawn
- …