3,942 research outputs found
Generation of spiral bevel gears with zero kinematical errors and computer aided tooth contact analysis
Kinematic errors in spiral bevel gears are a major source of noise and vibrations in transmissions. A method for the generation of Gleason's spiral bevel gears which provides conjugated gear tooth surfaces and an improved bearing contact was developed. A computer program for the simulation of meshing, misalignment, and bearing contact was written
The Structure of Barium in the hcp Phase Under High Pressure
Recent experimental results on two hcp phases of barium under high pressure
show interesting variation of the lattice parameters. They are here interpreted
in terms of electronic structure calculation by using the LMTO method and
generalized pseudopotential theory (GPT) with a NFE-TBB approach. In phase II
the dramatic drop in c/a is an instability analogous to that in the group II
metals but with the transfer of s to d electrons playing a crucial role in Ba.
Meanwhile in phase V, the instability decrease a lot due to the core repulsion
at very high pressure. PACS numbers: 62.50+p, 61.66Bi, 71.15.Ap, 71.15Hx,
71.15LaComment: 29 pages, 8 figure
PISA 2015: how big is the βmode effectβ and what has been done about it?
The Programme for International Student Assessment (PISA) is an important cross-national study of 15-year-oldsβ academic knowledge and skills. Educationalists and public policymakers eagerly await the tri-annual results, with particular interest in whether their country has moved up or slid down the international rankings, as compared to earlier rounds. In 2015 a major change was implemented in PISA, with the introduction of computer-based assessment. This has the potential to reduce comparability of PISA test scores across countries and over time. We investigate this issue using PISA 2015 field trial data for three countries: Germany, Sweden, and Ireland. We show how, if left unaccounted for, the change to computer-based testing could limit the comparability of PISA test scores. We then describe the methodology the study organisers have used to account for such mode effects. Our key conclusion is that although the adjustment made is unlikely to overcome all the potential challenges of switching to computer-based tests, it represents an improvement over the alternative of making no adjustment at all
Total energy differences between SiC polytypes revisited
The total energy differences between various SiC polytypes (3C, 6H, 4H, 2H,
15R and 9R) were calculated using the full-potential linear muffin-tin orbital
method using the Perdew-Wang-(91) generalized gradient approximation to the
exchange-correlation functional in the density functional method. Numerical
convergence versus k-point sampling and basis set completeness are demonstrated
to be better than 1 meV/atom. The parameters of several generalized anisotropic
next-nearest-neighbor Ising models are extracted and their significance and
consequences for epitaxial growth are discussed.Comment: 8 pages, 3 figures, Latex, uses epsfig and revte
Phase Estimation from Atom Position Measurements
We study the measurement of the position of atoms as a means to estimate the
relative phase between two Bose-Einstein condensates. First, we consider
atoms released from a double-well trap, forming an interference pattern, and
show that a simple least-squares fit to the density gives a shot-noise limited
sensitivity. The shot-noise limit can instead be overcome by using correlation
functions of order or larger. The measurement of the
-order correlation function allows to estimate the relative phase
at the Heisenberg limit. Phase estimation through the measurement of the
center-of-mass of the interference pattern can also provide sub-shot-noise
sensitivity. Finally, we study the effect of the overlap between the two clouds
on the phase estimation, when Mach-Zehnder interferometry is performed in a
double-well.Comment: 20 pages, 6 figure
Entanglement in Quantum Spin Chains, Symmetry Classes of Random Matrices, and Conformal Field Theory
We compute the entropy of entanglement between the first spins and the
rest of the system in the ground states of a general class of quantum
spin-chains. We show that under certain conditions the entropy can be expressed
in terms of averages over ensembles of random matrices. These averages can be
evaluated, allowing us to prove that at critical points the entropy grows like
as , where and are determined explicitly. In an important class of systems,
is equal to one-third of the central charge of an associated Virasoro algebra.
Our expression for therefore provides an explicit formula for the
central charge.Comment: 4 page
Thermodynamically Stable One-Component Metallic Quasicrystals
Classical density-functional theory is employed to study finite-temperature
trends in the relative stabilities of one-component quasicrystals interacting
via effective metallic pair potentials derived from pseudopotential theory.
Comparing the free energies of several periodic crystals and rational
approximant models of quasicrystals over a range of pseudopotential parameters,
thermodynamically stable quasicrystals are predicted for parameters approaching
the limits of mechanical stability of the crystalline structures. The results
support and significantly extend conclusions of previous ground-state
lattice-sum studies.Comment: REVTeX, 13 pages + 2 figures, to appear, Europhys. Let
Quantum test of the Universality of Free Fall using rubidium and potassium
We report on an improved test of the Universality of Free Fall using a
rubidium-potassium dual-species matter wave interferometer. We describe our
apparatus and detail challenges and solutions relevant when operating a
potassium interferometer, as well as systematic effects affecting our
measurement. Our determination of the E\"otv\"os ratio yields
with a combined standard uncertainty
of
The moral muteness of managers: an Anglo-American phenomenon? German and British managers and their moral reasoning about environmental sustainability in business
Several studies in the Anglo-American context have indicated that managers present themselves as morally neutral employees who act only in the best interest of the company by employing objective skills. The reluctance of managers to use moral arguments in business is further accentuated in the now common argument presented as a neutral fact that the company must always prioritise shareholder value. These and other commercial aims are seen as an objective reality in business, whilst questions about sustainability, environmental problems or fair trade are seen as emotional or moral ones; a phenomenon described as βmoral mutenessβ. This research explores whether this βmoral mutenessβ is an Anglo-American phenomenon and/or whether managers in other countries - in this case Germany - might express themselves in a different way. The focus is on moral arguments around environmental sustainability and the implications of this study for cross-cultural management. This article is based on a qualitative, comparative cross-cultural study of British and German managers in the Food Retail and Energy Sectors. In line with the studies mentioned above, British managers placed a strong emphasis on their moral neutrality. In contrast, German managers tended to use moral arguments when discussing corporate greening, often giving such arguments more weight than financial arguments. Overall, the study suggests that the βmoral mutenessβ of managers is a British phenomenon and quite distinct from the German approach. The article ends in a short exploration of how this understanding can help managers better manage people, organisations and change across cultures
ΠΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ ΠΌΠ΅ΡΠΎΠ΄Π° ΠΏΠΎΠ΄Π²ΠΈΠΆΠ½ΡΡ ΠΊΠ»Π΅ΡΠΎΡΠ½ΡΡ Π°Π²ΡΠΎΠΌΠ°ΡΠΎΠ² Π΄Π»Ρ ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ Π²Π½ΡΡΡΠ΅Π½Π½Π΅ΠΉ ΡΡΡΡΠΊΡΡΡΡ ΡΠ½Π΄ΠΎΠΏΡΠΎΡΠ΅Π·Π° ΡΠ°Π·ΠΎΠ±Π΅Π΄ΡΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΡΡΡΠ°Π²Π° ΡΠ΅Π»ΠΎΠ²Π΅ΠΊΠ°
ΠΠ° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΌΠ΅ΡΠΎΠ΄Π° ΠΏΠΎΠ΄Π²ΠΈΠΆΠ½ΡΡ
ΠΊΠ»Π΅ΡΠΎΡΠ½ΡΡ
Π°Π²ΡΠΎΠΌΠ°ΡΠΎΠ² ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ ΠΈΠ·ΡΡΠ΅Π½ΠΈΠ΅ Π²Π»ΠΈΡΠ½ΠΈΡ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΎΠ½Π½ΡΡ
ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΠΉ ΡΠ½Π΄ΠΎΠΏΡΠΎΡΠ΅Π·Π° ΡΠ°Π·ΠΎΠ±Π΅Π΄ΡΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΡΡΡΠ°Π²Π° ΡΠ΅Π»ΠΎΠ²Π΅ΠΊΠ° Π½Π° Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΎΠ½Π½ΡΠ΅ ΠΈ ΠΏΡΠΎΡΠ½ΠΎΡΡΠ½ΡΠ΅ ΡΠ²ΠΎΠΉΡΡΠ²Π°, Π° ΡΠ°ΠΊΠΆΠ΅ Π΄ΠΈΠ½Π°ΠΌΠΈΠΊΡ Π³Π΅Π½Π΅ΡΠ°ΡΠΈΠΈ ΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΏΠΎΠ²ΡΠ΅ΠΆΠ΄Π΅Π½ΠΈΠΉ Π² ΡΠΈΡΡΠ΅ΠΌΠ΅ "ΡΡΡΡΠ°Π²-ΡΠ½Π΄ΠΎΠΏΡΠΎΡΠ΅Π·-Π±Π΅Π΄ΡΠ΅Π½Π½Π°Ρ ΠΊΠΎΡΡΡ". Π‘ΡΡΡΠΊΡΡΡΠ° ΠΏΡΠΎΡΠ΅Π·Π° ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π»Π°ΡΡ Π²Π²Π΅Π΄Π΅Π½ΠΈΠ΅ΠΌ Π² ΡΠ΅ΠΉΠΊΡ Π΄Π΅ΠΌΠΏΡΠΈΡΡΡΡΠΈΡ
Π²ΠΊΠ»ΡΡΠ΅Π½ΠΈΠΉ ΠΈ Π½Π°Π½Π΅ΡΠ΅Π½ΠΈΠ΅ΠΌ ΠΏΠΎΠΊΡΡΡΠΈΡ Π½Π° Π½ΠΎΠΆΠΊΡ ΠΈΠΌΠΏΠ»Π°Π½ΡΠ°ΡΠ°. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ Π½Π°Π»ΠΈΡΠΈΠ΅ ΡΠ°ΠΊΠΈΡ
Π²ΠΊΠ»ΡΡΠ΅Π½ΠΈΠΉ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΈ Π½Π΅ ΠΈΠ·ΠΌΠ΅Π½ΡΠ΅Ρ ΠΏΡΠΎΡΠ½ΠΎΡΡΡ ΡΠΈΡΡΠ΅ΠΌΡ, Π½ΠΎ ΠΏΡΠΈ ΡΡΠΎΠΌ Π²Π΅Π΄Π΅Ρ ΠΊ Π·Π°ΠΌΠ΅ΡΠ½ΠΎΠΌΡ ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΡ ΠΏΡΠ΅Π΄Π΅Π»ΡΠ½ΠΎΠΉ Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΡΡΡΡΠΊΡΡΡΡ "ΠΊΠΎΡΡΡ - ΠΏΡΠΎΡΠ΅Π·", Π° ΡΠ°ΠΊΠΆΠ΅ ΠΎΠΊΠ°Π·ΡΠ²Π°Π΅Ρ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π½Π° Π΄ΠΈΠ½Π°ΠΌΠΈΠΊΡ Π·Π°ΡΠΎΠΆΠ΄Π΅Π½ΠΈΡ ΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΏΠΎΠ²ΡΠ΅ΠΆΠ΄Π΅Π½ΠΈΠΉ Π² ΠΊΠΎΡΡΠ½ΠΎΠΉ ΡΠΊΠ°Π½ΠΈ
- β¦