Aim: To estimate and compare the frictional forces engendered by three types of aestheticselfligating brackets with two straight wire alloys. Materials: The study comprised of a total of 90 brackets, of which 30 passive (Damon clear 2),30 active(GAC In-Ovation C) and 30 interactive (Empower clear) orthodontic brackets with a slot size of .022X.028 MBT prescription in combination with stainless ...

Goaf Frictional Ignition (GFI) poses a serious threat to the safety of underground coal mines, and has caused many underground fires and catastrophic explosions. This paper examined occurrences of GFI incidents and the underlying mechanisms of ignition source and environment. Most of these incidents were attributed to rock on rock frictional ignition. The eventuation of frictional ignition reli...

Simulating frictional contact between objects with complex geometry is important for 6-DoF haptic rendering applications. For example, friction determines whether components can be navigated past narrow clearances in virtual assembly. State-of-the-art haptic rendering of frictional contact either augments penalty contact with frictional penalty springs, which do not prevent sliding and cannot r...

Differential rotation between the neutron star crust and a more rapidly rotating interior superfluid leads to frictional heating that affects the star’s long-term thermal evolution and resulting surface emission. The frictional heating rate is determined by the mobility of the vortex lines that thread the rotating superfluid and pin to the inner crust lattice. If vortex pinning is relatively st...

We report on the frictional properties of a single contact between a glassy polymer lens and a flat silica substrate covered either by a disordered or by a self-assembled alkylsilane monolayer. We find that, in contrast to a widely spread belief, the Amontons proportionality between frictional and normal stresses does not hold. Besides, we observe that the velocity dependence of the sliding str...

Pricing in online markets has been of much interest to academics and practitioners, particularly for unique IT services. In this paper, we theorize and empirically examine three primary factors that affect provider pricing of outsourced IT services: production cost, competitive dynamics (accounting for competitors’ attributes) and frictional cost (accounting for buyers’ information). We test th...

We consider the problem of planning manipulation tasks in which rigid body dynamics are significant and the rigid bodies undergo frictional contacts. We develop a dynamic model with frictional compliant contacts, and a time-stepping algorithm that lends itself to finding trajectories with constraints on the starting and goal conditions. Because we explicitly model the local compliance at the co...

We use the theory of the fluctuating electromagnetic field to calculate the frictional drag between nearby two-and three dimensional electron systems. The frictional drag results from coupling via a fluctuating electromagnetic field, and can be considered as the dissipative part of the van der Waals interaction. In comparison with other similar calculations for semiconductor two-dimensional sys...

Graphene monolayers are known to display domains of anisotropic friction with twofold symmetry and anisotropy exceeding 200%. This anisotropy has been thought to originate from periodic nanoscale ripples in the graphene sheet, which enhance puckering around a sliding asperity to a degree determined by the sliding direction. Here we demonstrate that these frictional domains derive not from struc...

This paper examines the two-sided matching problem where the agents on each side of the market are heterogeneous and the matching process is time consuming. This is cast in a labor market setting where workers of different skills match with different machine qualities. I characterize the efficient allocation and then show that it can be decentralized by a market mechanism. The efficient assignm...