physics.ubs.ca Imagine stepping off the edge of a swimming pool, only to find that your foot deflects the surface of the water without breaking it, as if held by some impenetrable skin. As you walk forward, the water continues to support you; but if you take a running leap and bring your full weight down on the surface, then it snaps open to envelop you without a splash. Rather than plunging to...

Nacrtak The importance of forest wood chips as fuel for energy production will increase relative to sawmill by-products. The additional production is not a question of potential (harvesting residues, wood from thinning, coppice stands and short rotation forests) but more so a question of economic feasibility. The analyses of different chip production systems resulted in the identification of tw...

Acknowledging the absence of up-to-date empirical data on the value retention, service life and annual use of chipping machinery, in 2017 the authors surveyed the records kept by 50 contractors offering biomass chipping services. The machine fleet and operations in this survey could be taken as representative for most of Europe, where the biomass sector is well established and is facing further...

In tree-length harvesting operations, the trees are usually delimbed and topped in the woods. Sawlogs are bucked, and pulpwood is loaded tree-length. The use of in-woods chipping has been limited to energywood production because high bark content limits the use of whole-tree chips as pulp furnish. Flail delimbing and debarking allows economical processing and chipping of whole trees in the wood...

A number of devices in MEMS introduce frictional contacts between moving surfaces, resulting in particle generation. In this paper, we explore the nano-scale abrasion characteristics of four materials that are commonly encountered in MEMS devices and packages: aluminum (Al), silicon (Si), Pyrex glass, and glass-mica ceramic (Macor). A commercial scribing tool has been adapted to provide control...

Magnetic abrasive finishing can be classified as a non-traditional super finishing method for finishing surfaces with different shapes and working materials like flat plates, shafts, bearings parts, screws, tubes and many other mechanical parts that need good surface finishing properties. MAF is effective in polishing, cleaning, deburring and burnishing metal parts. The most important parameter...

Short rotation poplar plantations grow on flat and even terrain, the interrow spacing is wide enough for easy machine access. If terrain firm enough, one may consider moving classic roadside chipping operation directly into field (i.e., chipping), thus saving wood extraction cost. This study compared efficiency cost of conducted with exactly same equipment, to assess benefits offered by versati...

Chipping of the ceramic veneer is reported as a frequent occurrence when using zirconia-based fixed dental prostheses (FDPs). One possible cause of this complication is the inadequate support of the veneering ceramic by the zirconia substructure. In this article, early clinical observations from patients treated with 96 zirconia-based ceramic single- and multiple-unit FDPs on natural teeth and ...