scholarly journals Detailed Studies of Electron Cooling Friction Force

2006 ◽  
Author(s):  
A. V. Fedotov
Keyword(s):  
Friction Force ◽  
Electron Cooling

A very cold laser-induced electron beam for studies on the friction force in an electron cooling experiment

1989 ◽  
Vol 101 (2) ◽  
pp. 333-343 ◽  
Author(s):  
R. Calabrese ◽  
F. Ciccacci ◽  
V. A. Lebedev ◽  
V. V. Parkhomchuk ◽  
A. A. Seriy ◽  
...  
Keyword(s):  
Electron Beam ◽  
Friction Force ◽  
Electron Cooling

Friction Force and Stresses Analysis for Contact of Assembled Details

2006 ◽  
Vol 113 ◽  
pp. 334-338
Author(s):  
Z. Dreija ◽  
O. Liniņš ◽  
Fr. Sudnieks ◽  
N. Mozga
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Plastic Deformation ◽  
Friction Force ◽  
Sliding Friction ◽  
Friction Model ◽  
Contact Interface ◽  
Finite Element Program ◽  
Elastic Plastic ◽  
Element Program

The present work deals with the computation of surface stresses and deformation in the presence of friction. The evaluation of the elastic-plastic contact is analyzed revealing three distinct stages that range from fully elastic through elastic-plastic to fully plastic contact interface. Several factors of sliding friction model are discussed: surface roughness, mechanical properties and contact load and areas that have strong effect on the friction force. The critical interference that marks the transition from elastic to elastic- plastic and plastic deformation is found out and its connection with plasticity index. A finite element program for determination contact analysis of the assembled details and due to details of deformation that arose a normal and tangencial stress is used.

scholarly journals Ultrafast electron cooling in an expanding ultracold plasma

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tobias Kroker ◽  
Mario Großmann ◽  
Klaus Sengstock ◽  
Markus Drescher ◽  
Philipp Wessels-Staarmann ◽  
...  
Keyword(s):  
Theoretical Models ◽  
Einstein Condensate ◽  
Direct Access ◽  
Electron Cooling ◽  
Plasma Dynamics ◽  
Strongly Coupled ◽  
Bose Einstein Condensate ◽  
Ultracold Plasma ◽  
Strongly Coupled Plasma ◽  
Bose Einstein

AbstractPlasma dynamics critically depends on density and temperature, thus well-controlled experimental realizations are essential benchmarks for theoretical models. The formation of an ultracold plasma can be triggered by ionizing a tunable number of atoms in a micrometer-sized volume of a 87Rb Bose-Einstein condensate (BEC) by a single femtosecond laser pulse. The large density combined with the low temperature of the BEC give rise to an initially strongly coupled plasma in a so far unexplored regime bridging ultracold neutral plasma and ionized nanoclusters. Here, we report on ultrafast cooling of electrons, trapped on orbital trajectories in the long-range Coulomb potential of the dense ionic core, with a cooling rate of 400 K ps−1. Furthermore, our experimental setup grants direct access to the electron temperature that relaxes from 5250 K to below 10 K in less than 500 ns.

scholarly journals Bubble wall velocity at strong coupling

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Francesco Bigazzi ◽  
Alessio Caddeo ◽  
Tommaso Canneti ◽  
Aldo L. Cotrone
Keyword(s):  
Phase Transitions ◽  
Steady State ◽  
Friction Force ◽  
Bubble Velocity ◽  
Strongly Coupled ◽  
First Order ◽  
Black Hole Background ◽  
Different Dimensions ◽  
Holographic Description ◽  
First Order Phase

Abstract Using the holographic correspondence as a tool, we determine the steady-state velocity of expanding vacuum bubbles nucleated within chiral finite temperature first-order phase transitions occurring in strongly coupled large N QCD-like models. We provide general formulae for the friction force exerted by the plasma on the bubbles and for the steady-state velocity. In the top-down holographic description, the phase transitions are related to changes in the embedding of $$ Dq\hbox{-} \overline{D}q $$ Dq ‐ D ¯ q flavor branes probing the black hole background sourced by a stack of N Dp-branes. We first consider the Witten-Sakai-Sugimoto $$ D4\hbox{-} D8\hbox{-} \overline{D}8 $$ D 4 ‐ D 8 ‐ D ¯ 8 setup, compute the friction force and deduce the equilibrium velocity. Then we extend our analysis to more general setups and to different dimensions. Finally, we briefly compare our results, obtained within a fully non-perturbative framework, to other estimates of the bubble velocity in the literature.

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

2021 ◽  
pp. 135065012110105
Author(s):  
Nguyen Van Liem ◽  
Wu Zhenpeng ◽  
Jiao Renqiang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Contact Force ◽  
Distribution Density ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Combined Model ◽  
Obvious Effect ◽  
Area Density

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

scholarly journals Nanomaterials Application in Orthodontics

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 337
Author(s):  
Wojciech Zakrzewski ◽  
Maciej Dobrzynski ◽  
Wojciech Dobrzynski ◽  
Anna Zawadzka-Knefel ◽  
Mateusz Janecki ◽  
...  
Keyword(s):  
Friction Force ◽  
Material Properties ◽  
Orthodontic Treatment ◽  
Mechanical Characteristics ◽  
Current Knowledge ◽  
Scientific Work ◽  
Orthodontic Appliances ◽  
Orthodontic Movement ◽  
Enamel Demineralization

Nanotechnology has gained importance in recent years due to its ability to enhance material properties, including antimicrobial characteristics. Nanotechnology is applicable in various aspects of orthodontics. This scientific work focuses on the concept of nanotechnology and its applications in the field of orthodontics, including, among others, enhancement of antimicrobial characteristics of orthodontic resins, leading to reduction of enamel demineralization or control of friction force during orthodontic movement. The latter one enables effective orthodontic treatment while using less force. Emphasis is put on antimicrobial and mechanical characteristics of nanomaterials during orthodontic treatment. The manuscript sums up the current knowledge about nanomaterials’ influence on orthodontic appliances.

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