Innovation Ultrasonic Assistant Soldering in Electronics

Innovative approaches in ultrasonic assistant soldering consist consists of increasing the activity of cavitation and accelerating diffusion processes at the interface between the solder and the soldering material. Besides that, it improves the effectiveness of cavitation processes in melts by saturating gas cavities with diamete rs that are smaller than the resonant sizes of cavitation germs. Gas saturation of liquids and melts raises level of cavitation pressure by 20 25%25%, that intensifies US processing of cleaning, soldering and metallization. Modelling diffusion process showed that the US activation increased the concentration of diffusing elements of Zn and Al in the interface depth by 15 20% on average, and the combined activation by the US and electric field increased it by 30 45%. Furthermore, as the energy quantity adsorbed by melt increases, increased amplitude and frequency of US vibrations induces concentration rise. The heat energy was also boosted by combining the activation of the melt–soldered material system with US vibrations energy and high current pulses. This allows for a faster increase in soldering temperature, as well as improved solder wettability.

A short proof of backward uniqueness for some geometric evolution equations

We present a simple, direct proof of the backward uniqueness of solutions to a class of second-order geometric evolution equations which includes the Ricci and cross-curvature flows. The proof, based on a classical argument of Agmon–Nirenberg, uses the logarithmic convexity of a certain energy quantity in the place of Carleman inequalities. We further demonstrate the applicability of the technique to the [Formula: see text]-curvature flow and other higher-order equations.

EFFECTIVE OPERATION INVESTIGATION OF UNGLAZED SOLAR AIR COLLECTOR / NEĮSTIKLINTO ORINIO SAULĖS KOLEKTORIAUS EFEKTYVAUS VEIKIMO TYRIMAS

The article presents results of an effective operation analysis of VGTU Environmental Engineering Faculty southern facade integrated unglazed transpired solar collector. During previous research the importance to evaluate influence to ventilation system by such type of collectors was observed. The assessment of analysed collector aerodynamics showed that under specific solar radiation and air flow conditions the amount of energy generated by collector could be smaller than the energy quantity consumed by fans for air suction. The study provides analysis of the coefficient of performance rates and quantities of generated and consumed energy under different operation conditions. The effective operation conditions of collector committed during this research could be useful for designing or creating algorithm for such device. Straipsnyje pristatoma VGTU Aplinkos inžinerijos fakulteto pietiniame fasade integruoto neįstiklinto orinio saulės kolektoriaus efektyvaus veikimo analizė bei jos rezultatai. Ankstesnio tyrimo metu pastebėta, kad, analizuojant tokio tipo kolektorių, svarbu atsižvelgti į jo poveikį vėdinimo sistemai. Įvertinus analizuojamojo kolektoriaus aerodinamines savybes, nustatyta, kad, esant tam tikroms oro srautų ir saulės spinduliuočių vertėms, įrenginio pagamintas energijos kiekis gali būti mažesnis už orui siurbti naudojamų ventiliatorių vartojamą energijos kiekį. Tyrime pateikiama kolektoriaus energijos transformavimo rodiklių bei pagamintų ir suvartotų energijos kiekių kitimo analizė, esant skirtingiems veikimo režimams. Nustatyti kolektoriaus efektyvaus veikimo režimai gali būti naudingi projektuojant ar kuriant tokio tipo įrenginių valdymo algoritmą.

Obtaining and Trademark of Copper Molybdenum Oxide from the CuMoO4 Sample Using Carbon as a Reducing Agent

This article discusses the calculation of the apparent activation energy (CuMoO4 + C) on the DTA curve, to study and optimize the time-temperature synthesis mode, in particular the activation energy. Activation energy allows us to investigate the elementary act of chemical interaction. Thus, we propose to use this method to calculate Eact interaction processes (CuMoO4 + C) in the solid phase synthesis occurring during the reinforcement. The research results are checked by thermodynamic calculations. The results obtained allow us to trace the energy quantity expended to start the reaction.

Advances in Energy Conservation of China Steel Industry

The course, technical progresses, and achievements of energy conservation of China steel industry (CSI) during 1980–2010 were summarized. Then, the paper adoptede-pmethod to analyze the variation law and influencing factors of energy consumptions of large- and medium-scale steel plants within different stages. It is pointed out that energy consumption per ton of crude steel has been almost one half lower in these thirty years, with 60% as direct energy conservation owing to the change of process energy consumption and 40% as indirect energy conservation attributed to the adjustment of production structure. Next, the latest research progress of some key common technologies in CSI was introduced. Also, the downtrend of energy consumption per ton of crude steel and the potential energy conservation for CSI during 2011–2025 were forecasted. Finally, it is indicated that the key topic of the next 15 years’ research on the energy conservation of CSI is the synergistic operation of material flow and energy flow. It could be achieved by the comprehensive study on energy flow network optimization, such as production, allocation, utilization, recovery, reuse, and resource, according to the energy quantity, quality, and user demand following the first and second laws of thermodynamics.