The study of the complex thread knurling process

The study carried out to research a manufacturing process of long products for mining industry by a method of cold knurling, in particular, on a stud of a self-drilling bolt used for strengthening of mountain rocks. The solution of the task was obtained by mathematical simulation of the knurling process in the FE software package that allows establishing stress-strain state parameters necessary to analyze forming and loading of the process. According to the R&D carried out on a basis of the two-rolled screw thread rolling machine was developed a technological process for which the knurling rollers were design and created. The manufactured pilot batch of items that's meeting the requirements for such type of anchors speaks of capability to maintain low-series production of self-drilling fasteners based on the complex profile cold knurling method of a long billet. © Published under licence by IOP Publishing Ltd

Electrical Discharge in a Cavitating Liquid under an Ultrasound Field

A theoretical model for an electrical discharge in a cavitating liquid is developed and compared with experiments for the optimization of the water treatment device. The calculations based on solution of the Noltingk─Neppiras equation support the hypothesis that the electric field promotes the formation of vapor microchannels inside a liquid gap between the electrodes, where at a low gas pressure Paschen’s conditions of rupture and abnormal glow discharge maintenance in those microchannels are fulfilled. Theoretical analysis of the cavitation processes and the discharge formation processes is in qualitative agreement with the experimental data obtained in this work in a water treatment device using a hydrodynamic emitter. The following graphic illustrates the experimental setup: (1) feeding tank, (2) hydrodynamic emitter, (3) zone of cavitation inside the plasma reactor, (4) high-frequency generator of electric impulses, and (5) outlet.</p

EBSD mapping of herringbone domain structures in tetragonal piezoelectrics

Herringbone domain structures have been mapped using electron backscatter diffraction (EBSD) in two tetragonal piezoelectrics, lead zirconate titanate, [Pb(Zr,Ti)O&lt;sub&gt;3&lt;/sub&gt;] and bismuth ferrite – lead titanate, [(PbTi)&lt;sub&gt;0.5&lt;/sub&gt;(BiFe)&lt;sub&gt;0.5&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;]. Analysis of the domain misorientations across the band junctions shows that the structures correspond very well to crystallographic models. High resolution mapping with a 20 nm step size allowed the crystal rotation across one of these band junctions in lead zirconate titanate to be studied in detail and allowed an improved estimation of the peak strain at the junction, of 0.56 GPa. The significance of this for crack nucleation and propagation in such materials is discussed

Diel Movements of Juvenile Illex illecebrosus and Other Cephalopods in the Shelf Water-Slope Water Frontal Zone off the Scotian Shelf in Spring

Vertical water structure at two diel stations in the Shelf Water-Slope Water frontal zone seaward of the Scotian Shelf could be classified into five layers on the basis of some rather specific hydrographic characteristics. The near-surface layer (0-30 m) consisted of Shelf Water of low temperature and salinity, the second layer (30-100 m) represented the transition from Shelf Water to Slope Water, the third layer (100-200 m) consisted of Slope Water with maximum temperature and salinity, the fourth layer (200-300 m) extended from the lower boundary of Slope Water to the depth of minimum oxygen content, and the fifth layer (300-500 m) extended downward to the upper boundary of North Atlantic Central Water. Vertical distribution and diel migrations of juvenile Illex illecebrosus were closely associated with these layers and differed for the three modal size-groups (3, 5 and 8 cm mantle length) of squid that were caught in a small-meshed midwater trawl. They preferred the second and fourth layers of increasing and decreasing temperatures respectively and tended to avoid the maximum temperatures of the third layer. The vertical distribution of other squid species, euphausiids and planktonic fishes seemed to be closely related to the hydrography of the defined layers

Studying damage accumulation in martensitic corrosion-resistant steel under cold radial reduction

Cold radial reduction of specimens made of the Kh17N2 corrosion-resistant martensitic steel is studied on a lever-type radial-forging machine (RFM). The mechanical properties of the deformed specimens, the "damage accumulation - strain" relation in the specimens are obtained with the application of hydrostatic and fractographic methods for fractured specimens. The damage of the Kh17N2 corrosion-resistant steel is evaluated as a result of an experimental study considering the data of simulation by a complex finite element model of cold deformation on a lever-type RFM. © 2017 Author(s)

Ultrasound-assisted cold pasteurization in liquid or SC-CO2

Various types of chemical and physical protocols are used, thermal treatment in particular, to increase the quality of bulk food products (for example, dates or some sort of nuts) and extend shelf life, and combinations of methods are frequently used to achieve the best results. However, the use of these processing methods is not always the best option to preserve the initial taste and appearance of food products. For instance, a product may lose its initial natural appearance and acquire different flavors due to chemical transformations that occur at certain temperatures or when the products are treated with chemicals. Non-thermal treatment methods are called “cold” pasteurization. This is a set of advanced techniques that are based on physical and chemical effects that do not result in the structural food-product transformations caused by heating. We have developed and tested a new technique for efficient food-product processing and cold pasteurization in an ultrasonic field under pressure in an atmosphere of supercritical or subcritical carbon dioxide. A laboratory-scale unit that was designed and built for this purpose has experimentally proven the feasibility of this process and demonstrated high efficiency in suppressing pathogenic flora