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Abstrakt

Directional solidification of the Fe - 4,3 wt % C alloy was performed with the pulling rate equal to v=83 μm/s. Sample was frozen during solidification to reveal the shape of the solid/liquid interface. Structures eutectic pyramid and spherolitic eutectic were observed. The solidification front of ledeburite eutectic was revealed. The leading phase was identified and defined.
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Microwave sintering process was employed to agglomerate ferromanganese alloy powders. The effects of sintering temperature, holding time and particle size composition on the properties and microstructure of sintering products were investigated. The results was shown that increasing sintering temperature or holding time appropriately is beneficial to increase the compressive strength and volume density. SEM and EDAX analysis shows that the liquid phase formed below the melting point in the sintering process, which leads to densification. XRD patterns indicate that the main reaction during microwave sintering is the decarbonization and carburization of iron carbide phase. The experiment demonstrate that the optimum microwave sintering process condition is 1150°C, 10 min and 50% content of the powders with the size of –75 μm
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439L stainless steel composites blended with fifteen micron SiC particles were prepared by uniaxial pressing of raw powders at 100 MPa and conventional sintering at 1350oC for 2 h. Based on the results of X-ray diffraction analysis, dissolution of SiC particles were apparent. The 5 vol% SiC specimen demonstrated maximal densification (91.5%) among prepared specimens ­(0-10 vol% SiC); the relative density was higher than the specimens in the literature (80-84%) prepared by a similar process but at a higher forming pressure (700 MPa). The stress-strain curve and yield strength were also maximal at the 5 vol% of SiC, indicating that densification is the most important parameter determining the mechanical property. The added SiC particles in this study did not serve as the reinforcement phase for the 439L steel matrix but as a liquid-phase-sintering agent for facilitating densification, which eventually improved the mechanical property of the sintered product.
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Spatial light modulators (SLM) are devices used to modulate amplitude, phase or polarization of a light wave in space and time. Current SLMs are based either on MEMS (micro-electro-mechanical system) or LCD (liquid crystal display) technology. Here we report on the parameters, trends in development and applications of phase SLMs based on liquid crystal on silicon (LCoS) technology. LCoS technology was developed for front and rear projection systems competing with AMLCD (active matrix LCD) and DMD (Digital Mirror Device) SLM. The reflective arrangement due to silicon backplane allows to put a high number of pixels in a small panel, keeping the fill-factor ratio high even for micron-sized pixels. For coherent photonics applications the most important type of LCoS SLM is a phase modulator. In the paper at first we describe the typical parameters of this device and the methods for its calibration. Later we present a review of applications of phase LCoS SLMs in imaging, metrology and beam manipulation, developed by the authors as well as known from the literature. These include active and adaptive interferometers, a smart holographic camera and holographic display, microscopy modified in illuminating and imaging paths and active sensors.
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Abstrakt

To find effective and practical methods to distinguish gas-liquid two-phase flow patterns, new flow pattern maps are established using the differential pressure through a classical Venturi tube. The differential pressure signal was first decomposed adaptively into a series of intrinsic mode functions (IMFs) by the ensemble empirical mode decomposition. Hilbert marginal spectra of the IMFs showed that the flow patterns are related to the amplitude of the pressure fluctuation. The cross-correlation method was employed to sift the characteristic IMF, and then the energy ratio of the characteristic IMF to the raw signal was proposed to construct flow pattern maps with the volumetric void fraction and with the two-phase Reynolds number, respectively. The identification rates of these two maps are verified to be 91.18% and 92.65%. This approach provides a cost-effective solution to the difficult problem of identifying gas-liquid flow patterns in the industrial field.
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