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Electrical energy conversion characteristics based on underwater high-voltage pulse discharge

Yan Dong, Chen Songbai, Wu Qiong, Zhang Fengxiang, Lai Lipeng, Chen Inchen

Journal of Power Technologies

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2021

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Vol. 101, nr 4

190--201

EN

Underwater high-voltage (HV) pulse discharge mainly involves the process of HV discharge, breaking down water and releasing huge amounts of electrical energy, which is then rapidly converted into plasma. The plasma expands and creates shock waves and bubble pulsation effects. These effects are the main ways in which electrical energy transfers into mechanical energy. A breakdown process analysis model and an experimental method are proposed with a view to revealing the energy conversion characteristics during underwater pulse discharge and to understand the basic physical process. A plasma channel model was established in combination with the existing fundamentals of electricity and theoretical analysis. In addition, the discharge process was analyzed, along with shock wave and bubble pulsation action characteristics, on the basis of an underwater pulse discharge experiment. Meanwhile, theoretical analysis revealed the basic physical process involved in the electrical energy conversion effect. The results demonstrate the following: (1) The vaporization-ionization" breakdown model divides the breakdown process into three stages (i.e., heating effect, breakdown detonation and mechanical energy effect stages); (2) the heating effect stage is a phase prior to breakdown, which possesses significant heating characteristics and generates initial plasma; (3) a large electric current (104A) during the breakdown process heats the plasma channel to a high-temperature, where it becomes dense; this condition is followed by an instant decrease in channel resistance; the breakdown current peak depends on the residual voltage at the moment of breakdown; (4) during the breakdown detonation stage, discharge breakdown occurs, along with electric arc detonation. After the heating gasification process, when the electrical field intensity is suficient, the high-temperature HV plasma rapidly expands outward, resulting in a rapid conversion from electrical energy to mechanical energy. Thus, shock waves are formed, followed by bubble pulsation. The proposed method provides a good prospect for the application of underwater HV pulse discharge technology in the field of engineering.

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Litter Spider Communities and their Effects on Invertebrate Fauna and Decomposing Rates in Nanjenshan Rain Forest, Taiwan

Hou Ping-Chun Lucy, Chien Hao-Chiang, Liu Ren-Tao, Steinberger Yosef

Polish Journal of Ecology

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2019

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Vol. 67, nr 3

231--246

EN

Spiders are among the most important predators in forest litter layer that control food chain and decomposition process. However, little is known about the changes in litter-spider communities from wind-exposed to wind-shielded areas during monsoon seasons, and their roles in litter arthropod distribution and decomposition processes. In the present study, the densities and diversities of the spider communities in litter were examined at the two locations in monsoon and non-monsoon seasons in southern Taiwan. Enclosures with/without the spider Ctenus yaeyamensi were set up to compare litter arthropod distribution and decomposition rates in litterbags in different sampling units. It was found that the mean density of litter spiders was significantly greater in wind-shielded area than wind-exposed area. There was a marked impact of structure and depth of litter layers on guild composition, but not on the diversity indices of the litter spider communities. The litter invertebrates and decomposition rates did not differ between enclosures with/without spiders. However, there was a marked difference in litter arthropod abundance between monsoon and non-monsoon seasons in wind-exposed areas. The decomposition rate was remarkably greater in non-monsoon seasons than in monsoon seasons, whereas there were no marked differences between wind-shielded and wind-exposed locations. It was concluded that litter arthropod distribution and related decomposition were affected by variation of monsoon seasons but not by spider presence/absence in Nanjenshan Rain Forest.

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System Approach to the Research Process in Problems of Textile Engineering and Technology

Wojtysiak J.

Fibres & Textiles in Eastern Europe

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2003

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Vol. 11, no. 4 (43)

86--89

EN

This paper presents a method of system approach to the realisation of the research process in textile engineering. A system of research actions based on the division of a textile manufacturing process has been devised in order to develop the manufacturing process for a given textile product. The two independent system types are singled out: - First: the autonomous anticipatory research cycles concerned with scientific examination of the problem for future use; - Second: the design/construction research cycles leading to a practical solution of the problem. The method presented enables the realisation of research processes in all areas of textile engineering.

PL

W artykule przedstawiona została aplikacja metody systemowego ujęcia środka technicznego, lub procesu wytwórczego w odniesieniu do procesu naukowo-badawczego. Pokazana została idea procesu badań naukowych w płaszczyźnie abstraktu iw płaszczyźnie konkretu. Dokonano dekompozycji procesu na operacje cząstkowe, które racjonalizują działania naukowo-badawcze. Zaprezentowany został model procesu realizacji POTRZEBY w ujęciu systemowym. W wyniku analizy tego modelu dokonano podziału procesu na proces ciągłego rozpoznania potrzeb i proces projektowo-konstrukcyjny np. nowego produktu, lub układu wytwórczego. Poddano te dwa procesy szczegółowej analizie w aspekcie podziału na materialne operatory przekształcające i intelektualne operatory przekształcające. Ten sposób ujęcia zagadnienia dobrze porządkuje proces naukowo-badawczy, nadając mu pełną czytelność w jego realizacji.