Archive for June, 2008
Using GIS in the Classroom to Investigate Energy
The National Educational Technology Standards for Students called for a classroom that is student-centered, with collaborative work in a multisensory, multimedia-based information exchange, where active inquiry-based learning and critical thinking are fundamental (International Society for Technology in Education [ISTE], 2000).
The purpose of this session is to illustrate how a Geographic Information System (GIS) can be incorporated into the classroom to support science and geographic inquiry and promote spatial thinking skills. According to the National Research Council (2006), spatial thinking is the knowledge, skills, and habits of mind to use concepts of space, tools of representation, and processes of reasoning in order to structure problems, find answers, and express solutions to those problems. › Continue reading
Indians and Dissembling Gentlemen in James Fenimore Cooper’s The Pioneers
It is well-documented that James Fenimore Cooper mined John Heckewelders History, Manners and Customs of the Indian Nations (1819) for information about the Lenape, Mahican, and Iroquois peoples that populate his Leatherstocking Tales. Scholarship tracing the Moravians influence on the novelist has consistently asserted both the reliability of Heckewelders Indians and Coopers faithfulness to those representations. Still beyond the ken of criticism, however, are matters that complicate Heckewelders claim that his unadorned picture of Indians is disinterested. With this in mind, I re-examine the literary relationship between Heckewelder and Cooper to interrogate in a new light the cultural politics of Coopers Indians. › Continue reading
Boundary Feedback Control for Mixing Enhancement of 2D Magnetohydrodynamic Channel Flow by Extremum Seeking
The interaction between electrically conducting fluids and magnetic fields in channel flows generates significant magnetohydrodynamics (MHD) effects, which often result in the need of higher pressure gradients to drive the fluid and lower heat transfer rates due to the laminarization of the flow. Active boundary control, either open-loop or closed-loop, can be employed to overcome this limitation. However, open-loop controllers generally have worse performance due to the uncertainties of the system. The extremum seeking scheme is a powerful tool to build feedback controllers based on existing open-loop controllers. In this work we demonstrate that by carefully tuning the extremum seeking the modified open-loop control scheme can be as good as the closed-loop control scheme presented in our earlier publications.
Novel MEMS-Based Technology for Measuring the Mechanical Properties of a Live Biological Cell
This paper presents an experimental platform for measuring the mechanical properties of live biological cells. The polymer-based MEMS device integrates a V-shaped electrothermal actuator (ETA) array, a force sensor, a displacement sensor, a thermal sensor, and a cell-positioning system in a single chip. The integrated cell-positioning system based on dielectrophoresis precisely places a cell to a designed spot, the MEMS ETA array provides a predefined deformation to the cell, the force and displacement sensors measure the magnitude of the force applied to the cell and the corresponding cell deformation, and the thermal sensor monitors temperature in the liquid cell medium environment during the experiment. This MEMS device was able to compress a NIH3T3 fibroblast cell and cause 25% mechanical strain.