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Full-Text Articles in Engineering

Microfluidic Pumping With Surface Tension Force And Magnetohydrodynamic Drive, Mian Qin Aug 2011

Microfluidic Pumping With Surface Tension Force And Magnetohydrodynamic Drive, Mian Qin

Publicly Accessible Penn Dissertations

Micropumping is difficult to design and control as compared to their macro-scale counterparts due to the size limitation.

The first part of this dissertation focuses on micropumping with surface tension forces. A simple, single-action, capillary pump/valve consisting of a bi-phase slug confined in a non-uniform conduit is described. At low temperatures, the slug is solid and seals the conduit. Once heated above its melting temperature, the liquid slug moves spontaneously along a predetermined path due to surface tension forces imbalance. This technique can be easily combined with other propulsion mechanisms such as pressure and magnetohydrodynamics (MHD).

The second part ...


Miniaturization Methods For Modular Robotics: External Actuation And Dielectric Elastomer Actuation, Paul J. White Aug 2011

Miniaturization Methods For Modular Robotics: External Actuation And Dielectric Elastomer Actuation, Paul J. White

Publicly Accessible Penn Dissertations

A conventional robot with fixed form cannot change its morphology to respond to changes in its environment or suit a specific task. In contrast, a self-reconfigurable modular robot can rearrange its modules to adapt to a task or its environment. Module miniaturization would enable applications requiring fine resolution such as dexterous manipulation and accurate three-dimensional physical representation. As the module's actuators limit its minimum size, we present two novel methods for enabling module miniaturization: external actuation and dielectric elastomer actuation.

With external actuation, modules reconfigure using forces provided by a controlled environment rather than internal actuators. The environment imposes ...


Patterning Of Alloy Precipitation Through External Pressure, Jack A. Franklin Dec 2010

Patterning Of Alloy Precipitation Through External Pressure, Jack A. Franklin

Publicly Accessible Penn Dissertations

Due to the nature of their microstructure, alloyed components have the benefit of meeting specific design goals across a wide range of electrical, thermal, and mechanical properties. In general by selecting the correct alloy system and applying a proper heat treatment it is possible to create a metallic sample whose properties achieve a unique set of design requirements. This dissertation presents an innovative processing technique intended to control both the location of formation and the growth rates of precipitates within metallic alloys in order to create multiple patterned areas of unique microstructure within a single sample. Specific experimental results for ...