objective: corrosion resistance is among the most important properties of metal alloys used in the oral cavity. consumption of acidic foods reduces the salivary ph and intensifies the corrosion of brackets and orthodontic wires. this study aimed to compare electro galvanic corrosion of different orthodontic brackets and wires and determine the amount of ions released into acidic artificial sali...

Abstract. The traditional Hamiltonian structure of the equations governing conservative Rayleigh-Bénard convection (RBC) is singular, i.e. it’s Poisson bracket possesses nontrivial Casimir functionals. We show that a special form of one of these Casimirs can be used to extend the bilinear Poisson bracket to a trilinear generalised Nambu bracket. It is further shown that the equations governing ...

The prevention of fall from height accidents has long been a popular topic in the field of construction safety. Previous research has indicated one of the potential hazards was induced by the use of steel bracket as scaffold support. While researchers are focusing to improve the existing scaffolding system, this research introduces a newly developed device to minimize fall accidents. The workin...

High sensitivity multi-constellation GNSS receivers can dramatically improve the satellite availability in an urban environment. However, positioning accuracy remains a challenge because of blockage, reflection and diffraction of signals by buildings. In typical urban positioning scenarios, the receiver often receives a mixture of nonline-of-sight (NLOS) signals, multipath-contaminated direct l...

height is amongst the most delicate subjects of geodesy. thanks to the global navigation satellite systems (gnss) like gps or glonass, 3d point positioning of points, by geometrical positioning, since years ago has become a common practice. the height derived from these ways has a geometrical concept. in civil projects the physical concept of the height is more demanded. orthometric height, , i...

When one uses the Dirac bracket, second class constraints become first class. Hence, they are amenable to the BRST treatment characteristic of ordinary first class constraints. This observation is the starting point of a recent investigation by Batalin and Tyutin, in which all the constraints are put on the same footing. However, because second class constraints identically vanish as operators ...

Rainfall measurement has an extensive historical precedent. Attempts have been made to standardise measurement procedures. This has never been successfully achieved. There are many sources of measurement error, some of which are compounded by poor rain gauge siting and a variation in gauge height. By far the worst cause of measurement inaccuracy is due to windinduced undercatching. Some solutio...

We report on a system of well-characterized source masses and their precision positioning system for a measurement of the Newtonian gravitational constant G using atoms as probes. The masses are 24 cylinders of 50 mm nominal radius, 150.2 mm nominal height, and mass of about 21.5 kg, sintered starting from a mixture of 95.3% W, 3.2% Ni, and 1.5% Cu. Density homogeneity and cylindrical geometry ...

<p style='text-indent:20px;'>We present twelve numerical methods for evaluation of objects and concepts from Poisson geometry. We describe how each method works with examples, explain it is executed in code. These include that evaluate Hamiltonian modular vector fields, compute the image under coboundary trace operators, Lie bracket differential 1–forms, gauge transformations, normal form...