Pump Specific Speed and Four Quadrant Data in Waterhammer Simulation: Taking Another Look

In some situations, it is possible for flow to go backwards through a pump during a transient waterhammer event. Sustained reverse flow will lead to reverse rotation. Understanding and predicting the pump behavior during waterhammer under these conditions is typically accomplished using previously published four quadrant pump data. Historically, the selection of which data to use is based on the similarity of pump specific speed. The weaknesses of using specific speed are described and an improved method of selecting appropriate four quadrant data is given based on fundamental curve shapes for head and power in the normal operating zone.

Evaluating the effect of micro-lubrication in orthopedic drilling

Achievement of low temperature, thrust force, and clean operating zone under with/without irrigation–assisted drilling is still a challenge in orthopedic surgery owing to substantial bone-tissue damage that extends the healing time. In order to mitigate the above challenges, a new micro-lubrication technique—a low-pressure cold mist impinged on the tool–bone joint interface and penetrating well into the bone surface to improve the cooling/lubrication efficiency—has been proposed in bone drilling. In this study, the aims are to characterize the effect of micro-cooling/lubrication on temperature and thrust force at different levels of cutting speed, feed rate, drill diameter, and coolant flow rate. For that purpose, a fresh calf bone was drilled through commercially available drill tool on three-axis mini-machine. The response surface methodology was applied to get the design of experiments, and the analysis of variance at p-values < 0.5 was used. Moreover, the empirical models were developed to examine the simultaneous effect of all the parameters on performance measures. The employed cooling-lubrication technology has shown a percentage reduction in temperature ranging from 34.3% to 48.3%, and 26.8%–35.9% under irrigation with respect to without-irrigation mode. For cutting force, these reductions are 13%–47.6% and 14.5%–44.2%, respectively. Furthermore, analysis of variance has highlighted the cutting speed and feed rate as the two most prominent parameters for temperature and thrust force under all the drilling modes. Relatively high-pressure cold mist in micro-lubrication has offered a lower temperature, thrust force, and clean operating zone under micro-lubrication mode than with/without-irrigation modes. Henceforth, the micro-lubrication technique has been found as a suitable cooling technique for drilling of bone in the viewpoint of temperature and thrust force.

Physico-chemical conditions of existence of early Cambrian chemotrophic microbiota in zone of influence of ore-forming hydrothermal solutions

Complex researches of the pyrite Early Cambrian Kyzyl-Tashtyg deposit (East Tuva) have allowed to reconstruct paleohydrothermal systems, to find out physical and chemical conditions of hydrothermal processes, and also to establish features of existence of ancient hydrothermal biota in the operating zone of the solutions, participating at all stages of formation of ore-bearing structures, since influence of postmagmatic fluids and finishing low temperature hydrotherms. The representative data on biota has been received at studying of the objects, which were in a zone of influence of rather low temperature hydrothermal systems. In one cases findings of microorganisms are dated for basalt complexes, containing ore body, and in other cases the found fauna is connected with ferruginous-siliceous sediments. It has been found out that microorganisms in the tonsil cavities of basalts evolved at the temperatures nearby 110-140°С under the influence of hydrothermal solutions. Much lower temperatures (to 100 °С) existed at development of micro-fossils in the quartz-hematite hydrothermal constructions of Kyzyl-Tashtyg deposit.