Modeling of Phase Changes of Hypo Eutectoid Steels

2016 ◽  
Vol 1 (1) ◽  
pp. 28-32
Author(s):  
Suresh Akella ◽  
◽  
B Ramesh Kumar ◽  
Keyword(s):  
Phase Changes

The Interpretation of Crystal Lattice Images

1972 ◽  
Vol 30 ◽  
pp. 550-551
Author(s):  
J. M. Cowley ◽  
Sumio Iijima
Keyword(s):  
Crystal Orientation ◽  
Diffraction Theory ◽  
Phase Changes ◽  
Electron Wave ◽  
Crystal Lattices ◽  
Heavy Atoms ◽  
Lattice Images ◽  
The Right ◽  
Intuitive Interpretation ◽  
Suitable Approximation

The imaging of detailed structures of crystal lattices with 3 to 4Å resolution, given the correct conditions of microscope defocus and crystal orientation and thickness, has been used by Iijima (this conference) for the study of new types of crystal structures and the defects in known structures associated with fluctuations of stoichiometry. The image intensities may be computed using n-beam dynamical diffraction theory involving several hundred beams (Fejes, this conference). However it is still important to have a suitable approximation to provide an immediate rough estimate of contrast and an evaluation of the intuitive interpretation in terms of an amplitude object.For crystals 100 to 150Å thick containing moderately heavy atoms the phase changes of the electron wave vary by about 10 radians suggesting that the “optimum defocus” theory of amplitude contrast for thin phase objects due to Scherzer and others can not apply, although it does predict the right defocus for optimum imaging.

Remote diagnostics of vibrations of dynamic objects by Doppler microwave sensors

Metrologiya ◽  
2020 ◽  
pp. 25-42
Author(s):  
Dmitrii V. Khablov
Keyword(s):  
Intelligent Systems ◽  
Electromagnetic Waves ◽  
Continuous Monitoring ◽  
Phase Changes ◽  
Vibration Diagnostics ◽  
Remote Diagnostics ◽  
Active Vibration ◽  
Dynamic Objects ◽  
Microwave Sensors ◽  
Non Destructive

This paper describes a promising method for non-contact vibration diagnostics based on the use of Doppler microwave sensors. In this case, active irradiation of the object with electromagnetic waves and the allocation of phase changes using two-channel quadrature processing of the received reflected signal are used. The modes of further fine analysis of the resulting signal using spectral or wavelet transformations depending on the nature of the active vibration are considered. The advantages of this non-contact and remote vibration analysis method for the study of complex dynamic objects are described. The convenience of the method for machine learning and use in intelligent systems of non-destructive continuous monitoring of the state of these objects by vibration is noted.

Influence of Metal Substitution on the Pressure-Induced Phase Change in Flexible Zeolitic Imidazolate Frameworks

2018 ◽  
Author(s):  
C. Michael McGuirk ◽  
Tomče Runčevski ◽  
Julia Oktawiec ◽  
Ari Turkiewicz ◽  
mercedes K. taylor ◽  
...  
Keyword(s):  
Phase Change ◽  
Single Crystal ◽  
Gas Adsorption ◽  
High Capacity ◽  
Phase Changes ◽  
Zeolitic Imidazolate Frameworks ◽  
Metal Substitution ◽  
Heat Management ◽  
Metal Organic ◽  
First Time

<p>Metal–organic frameworks that display step-shaped adsorption profiles arising from discrete pressure-induced phase changes are promising materials for applications in both high-capacity gas storage and energy-efficient gas separations. The thorough investigation of such materials through chemical diversification, gas adsorption measurements, and <i>in situ </i>structural characterization is therefore crucial for broadening their utility. We examine a series of isoreticular, flexible zeolitic imidazolate frameworks (ZIFs) of the type M(bim)<sub>2</sub> (SOD; M = Zn<sup> </sup>(ZIF-7), Co (ZIF-9), Cd (CdIF-13); bim<sup>–</sup> = benzimidazolate), and elucidate the effects of metal substitution on the pressure-responsive phase changes and the resulting CO<sub>2</sub> and CH<sub>4</sub> step positions, pre-step uptakes, and step capacities. Using ZIF-7 as a benchmark, we reexamine the poorly understood structural transition responsible for its adsorption steps and, through high-pressure adsorption measurements, verify that it displays a step in its CH<sub>4 </sub>adsorption isotherms. The ZIF-9 material is shown to undergo an analogous phase change, yielding adsorption steps for CO<sub>2</sub> and CH<sub>4</sub> with similar profiles and capacities to ZIF-7, but with shifted threshold pressures. Further, the Cd<sup>2+</sup> analogue CdIF-13 is reported here for the first time, and shown to display adsorption behavior distinct from both ZIF-7 and ZIF-9, with negligible pre-step adsorption, a ~50% increase in CO<sub>2</sub> and CH<sub>4</sub> capacity, and dramatically higher threshold adsorption pressures. Remarkably, a single-crystal-to-single-crystal phase change to a pore-gated phase is also achieved with CdIF-13, providing insight into the phase change that yields step-shaped adsorption in these flexible ZIFs. Finally, we show that the endothermic phase change of these frameworks provides intrinsic heat management during gas adsorption. </p>

Influence of microwave processing on frame of films glues on an aqueous basis

2016 ◽  
Author(s):  
С.П. Исаев ◽  
К.А. Шевчук
Keyword(s):  
Electromagnetic Field ◽  
Microwave Radiation ◽  
Polyvinyl Acetate ◽  
Wood Quality ◽  
Microwave Processing ◽  
Phase Changes ◽  
Microwave Range ◽  
Adhesive Film ◽  
Modern Development ◽  
Experimental Researches

Современное развитие деревоперерабатывающей отрасли сопровождается существенным ростом объемов готовой продукции, производимой на основе клееной древесины. Качество выпускаемой клееной продукции во многом определяется свойствами применяемых клеев. Экспериментально исследовано влияние электромагнитного поля СВЧ-диапазона на структуру клеев, применяемых для склеивания древесины. Установлено, что СВЧ-обработка оказывает существенное влияние на микроструктуру поливинилацетатного клея Dorus 072. Структура клеевой пленки, обработанной СВЧ-излучением, имеет более высокую дисперсность, по сравнению с исходным полимером, которая выражается в среднем уменьшении глобул в 1,4 раза. Исследование фазового контраста пленки поливинилацетатного клея, обработанного СВЧ-излучением, позволило установить, что после обработки уменьшается фазовая неоднородность клеевой пленки и имеет место углубление дисперсности глобул полимера, приводящее к увеличению степени его упаковки с образованием однородной по структуре пленки. Экспериментальные исследования пленок карбамидоформальдегидного клея Dorus FU 406, подвергнутого СВЧ-обработке, показали, что структуры образцов пленок как обработанного, так и необработанного, клея не отличаются значительными изменениями. Исследование фазового сдвига по поверхности образца пленки карбамидоформальдегидного клея отражает распределение свойств материала и показывает, что СВЧ-обработка клея способствует образованию квазигомогенной структуры, формирование которой подтверждается уменьшением различий в границах фазовых переходов микроструктур отвержденного полимера. На основании проведенных экспериментов по исследованию структуры пленок клеев, применяемых для склеивания древесины, установлено, что в результате воздействия электромагнитного поля СВЧ-диапазона на клеевые растворы осуществляется нетепловая модификация, сопровождающаяся уменьшением размеров макромолекул полимера и формированием плотно упакованной структуры пленки. Полученные результаты позволяют сделать вывод о целесообразности дальнейших исследований по модификации клеев СВЧ-обработкой. Modern development of woodworking branches is accompanied by essential growth of volumes of the finished goods manufactured on the basis of glued wood. Quality of let out glued production in many respects is defined by properties of applied glues. Influence of an electromagnetic field of a microwave range on frame of the glues applied to coagglutination of wood is experimentally investigated. It is positioned that microwave processing makes essential impact on a microstructure of polyvinyl acetate glue Dorus 072. The frame of the adhesive film treated by microwave radiation, has higher dispersity in comparison with initial polymer which is expressed on the average reduction of globules in 1,4 times. Research of phase contrast of a film of the treated polyvinyl acetate glue by microwave radiation has allowed to position that after processing phase heterogeneity of an adhesive film decreases and the excavation of dispersity of globules of the polymer, leading to augmentation of degree of its packaging, forming an unimodal film on frame takes place. Experimental researches of films of amino-formaldehyde glue Dorus FU 406, subjected to microwave processing, have shown that Frames of samples of films both treated, and untreated glue do not differ significant changes. Research of phase alteration on a surface of the sample of a film of amino-formaldehyde glue reflects allocation of properties of a stuff and shows that glue microwave processing promotes formation of the quasi-homogeneous frame which formation proves to be true reduction of distinctions in borders of phase changes of microstructures hardning polymer. On the basis of the made experiments on research of frame of films of the glues applied to coagglutination of wood it is positioned that as a result of influence of an electromagnetic field of the microwave oven of a range on glutinous solutions not thermal modification accompanied by reduction of the dimensions of macromolecules of polymer and formation of densely packed frame of a film is carried out. The received results allow to draw a conclusion on expediency of the further researches on modification of glues by microwave processing.

Modeling Phase Changes of Road Networks

2009 ◽  
Author(s):  
Arthur Huang ◽  
David Matthew Levinson
Keyword(s):  
Road Networks ◽  
Phase Changes

Gas motion in the cylindrical helicoid channel without rotation

2012 ◽  
Vol 9 (1) ◽  
pp. 162-164
Author(s):  
S.V. Khabirov
Keyword(s):  
Dispersion Curves ◽  
Phase Changes ◽  
Cylindrical Waves ◽  
Dispersion Ratio

Distribution of plane, spherical and cylindrical waves in steam-gaseous mixes with unequigranular particles and drops when one of fractions participates in phase changes is studied. The dispersion ratio is received, dispersion curves are calculated. Influence of a polydispersity of particles and drops on dispersion and a dissipation of small indignations is analysed.

Molecular orientation of liquid aliphatic hydrocarbons on the surface and at the interface with water

1989 ◽  
Vol 54 (12) ◽  
pp. 3171-3186 ◽  
Author(s):  
Jan Kloubek
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Molecular Orientation ◽  
Phase Changes ◽  
Aliphatic Hydrocarbons ◽  
Water Molecules ◽  
Free Energies ◽  
Dispersion Component ◽  
System Water ◽  
Orientation Of Molecules

The validity of the Fowkes theory for the interaction of dispersion forces at interfaces was inspected for the system water-aliphatic hydrocarbons with 5 to 16 C atoms. The obtained results lead to the conclusion that the hydrocarbon molecules cannot lie in a parallel position or be randomly arranged on the surface but that orientation of molecules increases there the ration of CH3 to CH2 groups with respect to that in the bulk. This ratio is changed at the interface with water so that the surface free energy of the hydrocarbon, γH, rises to a higher value, γ’H, which is effective in the interaction with water molecules. Not only the orientation of molecules depends on the adjoining phase and on the temperature but also the density of hydrocarbons on the surface of the liquid phase changes. It is lower than in the bulk and at the interface with water. Moreover, the volume occupied by the CH3 group increases on the surface more than that of the CH2 group. The dispersion component of the surface free energy of water, γdW = 19.09 mJ/m2, the non-dispersion component, γnW = 53.66 mJ/m2, and the surface free energies of the CH2 and CH3 groups, γ(CH2) = 32.94 mJ/m2 and γ(CH3) = 15.87 mJ/m2, were determined at 20 °C. The dependence of these values on the temperature in the range 15-40 °C was also evaluated.

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