Heat transfer during the boiling of liquid on microstructured surfaces. Part 2: Visualization of boiling and critical heat fluxes

Results from visualization of boiling process and experimental study of critical heat fluxes on microstructured surfaces are presented. The studied surfaces were obtained using the deforming cutting method and have different design shapes and sizes. Mechanisms of heat transfer enhancement are substantiated. A factor of 4.1 higher value of critical heat flux is obtained.     

Checking the operation of power units at thermal power stations in the mode of selective primary control of frequency during field system tests in the unified energy system

We present the results from unique system tests for ascertaining whether 210–800-MW power units can participate in selective primary and automatic secondary control of frequency and power. Conditions under which the tests were carried out are described in detail, the results of which confirmed that all the selected power units are ready to participate in selective primary and automatic secondary control of frequency and power.     

Fire Detection in Video Using LMS Based Active Learning

In this paper, a video based algorithm for fire and flame detection is developed. In addition to ordinary motion and color clues, flame flicker is distinguished from motion of flame colored moving objects using Markov models. Irregular nature of flame boundaries is detected by performing temporal wavelet analysis using Hidden Markov Models as well. Color variations in fire is detected by computing the spatial wavelet transform of moving fire-colored regions. Boundary of flames are represented in wavelet domain and irregular nature of the boundaries of fire regions is also used as an indication of the flame flicker. Decisions from sub-algorithms are linearly combined using an adaptive active fusion method. The main detection algorithm is composed of four sub-algorithms (i) detection of fire colored moving objects, (ii) temporal, and (iii) spatial wavelet analysis for flicker detection and (iv) contour analysis of fire colored region boundaries. Each algorithm yields a continuous decision value as a real number in the range [−1, 1] at every image frame of a video sequence. Decision values from sub-algorithms are fused using an adaptive algorithm in which weights are updated using the least mean square (LMS) method in the training (learning) stage.     

Cytocompatibility of polyhydroxybutyrate modified by plasma discharge

Properties of pristine and Ar plasma‐treated polyhydroxybutyrate (PHB) was studied by different methods as a function of the plasma discharge power and the time from the plasma exposure. Surface polarity was determined by goniometry, surface morphology and roughness was examined by atomic force microscopy, the amount of ablated layer was determined by gravimetry. The chemical structure of the surface was determined by photoelectron spectroscopy. Ablation of the surface layer upon plasma treatment and chemical etching was studied by gravimetry. Cytocompatibility of pristine and modified PHB was studied on mouse embryonic fibroblasts (NIH 3T3). Plasma modification leads to an increase in PHB surface polarity. By aging the surface polarity spontaneously decreases. The amount of ablated layer increases with plasma exposure time and discharge power. The plasma‐treated PHB is slightly soluble in water and considerably in methanol. After the plasma treatment the surface morphology and roughness is mildly changed. The plasma treatment improves cell adhesion, proliferation, and spreading homogeneity on the PHB surface. POLYM. ENG. SCI., 54:1231–1238, 2014. © 2013 Society of Plastics Engineers     

Durable grinding head for universal machines

A grinding head has been developed for a universal grinding machine. Operational tests confirm its long life and high performance.     

Optimization of the reforming process scheme

The possibility of obtaining stable reforming catalyzate with a benzene content of less than 1 wt. % was demonstrated by mathematical modeling. Two new versions of separation of benzene-forming components from the reaction mixture between the second and third levels were created. In comparison to the standard process, the first version ensures a benzene content in the reformate at the level of 0.01 wt. % with a 12% decreases in its yield, and the second version produces a benzene content at 0.47 wt. % with a 2.9% increase in the yield of reformate. The proposed versions are useful in production of export automotive gasoline that satisfies the Euro 2000 requirements. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 3, pp. 18 — 22, May — June, 2006.     

Growth of muscle cells on plasma-treated and gold nanoparticles-grafted polytetrafluoroethylene

Polytetrafluoroethylene (PTFE) was modified by Ar plasma with different exposure times. The plasma-activated surface was immersed in biphenyldithiol and subsequently in colloidal solution of Au nanoparticles. The changes in the surface wettability contact angle were examined by goniometry. Atomic force microscopy was used to determine the surface roughness and morphology. Changes in the chemical structure of the modified PTFE were studied using X-ray photoelectron spectroscopy (XPS) and electrokinetic analysis. The interaction of plasma-treated and grafted samples with vascular smooth muscle cell derived from the rat aorta was also studied. Specifically, the number and morphology of the adhered and proliferated cells on the PTFE were studied under in vitro conditions. The plasma treatment and the subsequent biphenyldithiol and Au nanoparticles grafting led to changes in the polymer surface chemistry, morphology, roughness and wettability. The polymer grafting with biphenyl-4,4′-dithiol (BFD) and subsequently with Au nanoparticles led to a decrease in the surface polarity. XPS measurements proved the presence of S and Au on the PTFE surface. Grafting with BFD and Au nanoparticles led to the decrease in surface roughness. In comparison with the pristine polymer, the plasma treatment and Au nanoparticles grafting increased the adhesion and proliferation of vascular smooth muscle cell.     

Practical system for the direct measurement of magneto-caloric effect by micro-thermocouples

A system for direct measurements of the magneto-caloric effect (MCE) exploits a rapid transport of a sample into or from magnetic field in permanent Halbach-type (1 T) or superconducting (4.7 T) magnets. Time dependence of induced changes of the sample temperature, ΔT(t), is detected directly by the differential Cu-Constantan-Cu micro-thermocouples with time steps of 300 ms. A sample placed inside an evacuated simple LN(2) cryostat is either totally isolated (adiabatic conditions) or partly connected with the copper sample holder (non-adiabatic conditions). The last arrangement (a model of the Brayton cycle) is used to simulate an application of MCE in refrigeration techniques. The relations describing ΔT(t) that allow an analysis of MCE of the studied materials are based on the general cooling law. The effect of the first-order magnetic transition on MCE of selected sample is also demonstrated by non-standard ΔT(t) curves measured in the last mentioned experimental arrangements.