BACKGROUND Enamel is the hardest and the stiffest tissue in the human body. The enamel undergoes multidirectional stresses, withstands multimillion chewing cycles, all while protecting the internal dentin and pulp from damage due to mechanical overload and exposure to the harsh chemical environment of the mouth. Raman spectroscopy allows to study enamel mineral content in a non-destructive and ...

the major problem in material removal process specially grinding is heat generation during the process and thus residual stress on the surface of product. therefore, optimization of high efficiency deep grinding (hedg) process is the main goal of this study in order to reduce heat and residual stress and also increase strength and surface hardness of aisi1045 steel by optimization of the proces...

We propose a new approach to understanding the algorithm-specific empirical hardness of NP-Hard optimization problems. In this work we focus on the empirical hardness of the winner determination problem—an optimization problem arising in combinatorial auctions—when solved by ILOG’s CPLEX software. We consider nine widely-used problem distributions and sample randomly from a continuum of paramet...

Nitriding is a surface treatment technique used to introduce nitrogen into metallic materials to improve their surface hardness, mechanical properties, wear resistance and corrosion resistance. In this research, the effects of plasma nitriding parameters including frequency and duty cycle were investigated on samples with different grooves dimensions. Steel blocks prepared from DIN1.2344 hot wo...

THE hardness of enamel and dentin has been determined by a variety of methods including abrasion," 2 pendulum,' scratch,4-7 and indentation" teehnics. Since the hardness of enamel and dentin has been shown to have considerable local variations, the methods using a microscratch or microindentation have been preferred. One of the more common types is the Knoop diamond indenter14 which has been us...

despite having some useful properties, stainless steels suffer from lack of suitable surface hardness. in this research electroless ni-b-tl coating was used with the aim to increase their surface hardness. the effects of nickel chloride, sodium borohydride, thallium nitrate and ethylendiamin on the chemical composition of coating were studied. to achieve an increase in hardness, the effects of ...

We address the question, \Are some classes of combinatorial optimization problems intrinsically harder than others, without regard to the algorithm one uses, or can diiculty only be assessed relative to particular algorithms?" We provide a measure of the hardness of a particular optimization problem for a particular optimization algorithm. We then present two algorithm-independent quantities th...

Titanium carbide-graphite (TiC/C) composite was successfully synthesized from Ti and C starting elemental powders using self-propagating high-temperature synthesis technique in an ultra-high plasma inert medium in a single stage. The TiC was exposed to a high-temperature inert medium to allow recrystallization. The product was then characterized using field emission scanning electron microscopy...

Effects of laser shock processing (LSP) on the cavitation erosion resistance of laser weldments were investigated by optical microscope (OM), scanning electron microscope (SEM) observations, roughness tester, micro hardness tester, and X-ray diffraction (XRD) technology. The morphological microstructures were characterized. Cumulative mass loss, incubation period, erosion rate, and damaged surf...