815 research outputs found
ΠΠ°ΠΊΠΎΠ½ΠΎΠΌΠ΅ΡΠ½ΠΎΡΡΠΈ ΡΠΈΠ½ΡΠ΅Π·Π° Π½Π°Π½ΠΎΠ΄ΠΈΡΠΏΠ΅ΡΡΠ½ΡΡ ΠΎΠΊΡΠΈΠ΄ΠΎΠ² ΠΌΠ΅Π΄ΠΈ ΡΠ»Π΅ΠΊΡΡΠΎΠ»ΠΈΠ·ΠΎΠΌ Π½Π° ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΠΌ ΡΠΎΠΊΠ΅ Π² ΡΠ°ΡΡΠ²ΠΎΡΠ΅ ΡΠ΅Π»ΠΎΡΠΈ
ΠΠΎΠΊΠ°Π·Π°Π½Π° Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΡ ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΡ ΠΎΠΊΡΠΈΠ΄ΠΎΠ² ΠΌΠ΅Π΄ΠΈ Ρ Π²ΡΡΠΎΠΊΠΎΠΉ ΠΏΠ»ΠΎΡΠ°Π΄ΡΡ ΡΠ΄Π΅Π»ΡΠ½ΠΎΠΉ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΡΠ»Π΅ΠΊΡΡΠΎΠ»ΠΈΠ·ΠΎΠΌ ΠΌΠ΅ΡΠ°Π»Π»ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΌΠ΅Π΄ΠΈ Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΠΎΠΊΠ° ΠΏΡΠΎΠΌΡΡΠ»Π΅Π½Π½ΠΎΠΉ ΡΠ°ΡΡΠΎΡΡ. ΠΠ·ΡΡΠ΅Π½Ρ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ, ΠΎΠΊΠ°Π·ΡΠ²Π°ΡΡΠΈΠ΅ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π½Π° ΡΠΊΠΎΡΠΎΡΡΡ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ ΠΎΠΊΡΠΈΠ΄ΠΎΠ². ΠΠΏΡΠ΅Π΄Π΅Π»ΡΠ½ ΡΠ°Π·ΠΎΠ²ΡΠΉ ΡΠΎΡΡΠ°Π² ΠΈ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ ΠΏΠΎΡΠΈΡΡΠΎΠΉ ΡΡΡΡΠΊΡΡΡΡ ΠΏΡΠΎΠ΄ΡΠΊΡΠΎΠ² ΡΠ»Π΅ΠΊΡΡΠΎΡΠΈΠ½ΡΠ΅Π·Π° Π² Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΠΈ ΠΎΡ ΡΠ΅ΠΆΠΈΠΌΠΎΠ² ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ ΠΏΡΠΎΡΠ΅ΡΡΠ°
The Expected Perimeter in Eden and Related Growth Processes
Following Richardson and using results of Kesten on First-passage
percolation, we obtain an upper bound on the expected perimeter in an Eden
Growth Process. Using results of the author from a problem in Statistical
Mechanics, we show that the average perimeter of the lattice animals resulting
from a very natural family of "growth histories" does not obey a similar bound.Comment: 11 page
Choice of steel material for bridge bearings to avoid brittle fracture
Bridge bearings need verification against brittle failure at low temperatures. The design of bearings according to EN 1337 may lead to structural components with thicknesses no longer covered in the relevant technical construction regulations. Due to its specific geometry, the loading and stressing and the fabrication process the prerequisites for using the rules in EN 1993 1 10 lead to conservative restrictions or uneconomical choice of steel material. For an economical bearing design further modifications of the existing rules are necessary. This report adapts the fracture mechanical approach used in EN 1993 1 10 and gives information for a βsafe-sidedβ choice of steel material for bearings. The main modifications refer to the hypothetical design crack scenario and the definition of the βnominal design stressβ at the geometric βhot-spotβ. An advanced methodology using Finite Elements and a simplified method using linear bending theory are evaluated.JRC.G.5-European laboratory for structural assessmen
Evidence for multiple mechanisms underlying surface electric-field noise in ion traps
Electric-field noise from ion-trap electrode surfaces can limit the fidelity of multiqubit entangling operations in trapped-ion quantum information processors and can give rise to systematic errors in trapped-ion optical clocks. The underlying mechanism for this noise is unknown, but it has been shown that the noise amplitude can be reduced by energetic ion bombardment, or βion milling,β of the trap electrode surfaces. Using a single trapped βΈβΈSrβΊ ion as a sensor, we investigate the temperature dependence of this noise both before and after ex situ ion milling of the trap electrodes. Making measurements over a trap electrode temperature range of 4 K to 295 K in both sputtered niobium and electroplated gold traps, we see a marked change in the temperature scaling of the electric-field noise after ion milling: power-law behavior in untreated surfaces is transformed to Arrhenius behavior after treatment. The temperature scaling becomes material-dependent after treatment as well, strongly suggesting that different noise mechanisms are at work before and after ion milling. To constrain potential noise mechanisms, we measure the frequency dependence of the electric-field noise, as well as its dependence on ion-electrode distance, for niobium traps at room temperature both before and after ion milling. These scalings are unchanged by ion milling.National Science Foundation (U.S.) (Award DMR-14-19807)United States. Air Force Office of Scientific Research (Contract FA8721-05-C-0002
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