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Full-Text Articles in Engineering
Effect Of Convection Associated With Cross-Section Change During Directional Solidification Of Binary Alloys On Dendritic Array Morphology And Macrosegregation, Masoud Ghods
ETD Archive
This dissertation explores the role of different types of convection on macrosegregation and on dendritic array morphology of two aluminum alloys directionally solidified through cylindrical graphite molds having both cross-section decrease and increase. Al- 19 wt. % Cu and Al-7 wt. % Si alloys were directionally solidified at two growth speed of 10 and 29.1 µm s-1 and examined for longitudinal and radial macrosegregation, and for primary dendrite spacing and dendrite trunk diameter.
Directional solidification of these alloys through constant cross-section showed clustering of primary dendrites and parabolic-shaped radial macrosegregation profile, indicative of “steepling convection” in the mushy-zone. The degree …
Design And Control Of A Powered Rowing Machine With Programmable Impedance, Jose Humberto De La Casas Zolezzi
Design And Control Of A Powered Rowing Machine With Programmable Impedance, Jose Humberto De La Casas Zolezzi
ETD Archive
Due to the rise of obesity, diabetes and cardiovascular disease, research in human performance and physical activity has received increased attention. Rowing machines are used for performance improvements through concentric exercises, however a combination of concentric and eccentric actions is known to improve the effectiveness of training. In this work, a conventional rowing machine was modified to include an electric motor and a robust impedance control system, enabling programmable impedance with concentric and eccentric capabilities. Eccentric exercises are known to contribute significantly to the efficacy of training and to diminish the detrimental effects of humans operating in microgravity for long …
Investigation Of Extremum Seeking Control For Adaptive Exercise Machines, Brahm T. Powell
Investigation Of Extremum Seeking Control For Adaptive Exercise Machines, Brahm T. Powell
ETD Archive
Many muscle rehabilitation regimens are non-adaptive and recommended subjectively by physicians. While there are advantages to having the feedback of a qualified physician, utilizing real-time muscle performance feedback could be beneficial. An extremum seeking control design is proposed to fulfill the need for an automated, load-varying exercise machine that can optimize muscle performance.
Several steps are outlined to contribute to the realization of this goal. First, the extremum seeking control scheme is discussed. Second, the Hill muscle model will be described. Theoretical muscle effort extrema will be derived for selected optimization cases, namely maximizing average squared power by varying load …
Electrochemical And Electroflotation Processes For Milk Waste Water Treatment, Alahmand Suleiman Mohammed
Electrochemical And Electroflotation Processes For Milk Waste Water Treatment, Alahmand Suleiman Mohammed
ETD Archive
The dairy industry generates abundant milk waste waters characterized by high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) concentrations that can be very harmful to the environment, if left untreated. Electrocoagulation (EC) has been in use for waste water treatment. The treatment application uses aluminum electrodes and iron or the combined hybrid Al/Fe electrodes. Milk waste water contains high concentration organic pollutants and the main constituents of those organics are carbohydrates, proteins and fats, originating from the milk. The process of separating the flocculated sludge from waste water that has been treated using the electrocoagulation process can be …