Electronic control of elastomeric microfluidic circuits with shape memory actuators

Recently, sophisticated fluidic circuits with hundreds of independent valves have been built by using multi-layer soft-lithography to mold elastomers. However, this shrinking of microfluidic circuits has not been matched by a corresponding miniaturization of the actuation and interfacing elements that control the circuits; while the fluidic circuits are small (~10–100 micron wide channels), the Medusa's head-like interface, consisting of external pneumatic solenoids and tubing or mechanical pins to control each independent valve, is larger by one to four orders of magnitude (mm to cm). Consequently, the dream of using large scale integration in microfluidics for portable, high throughput applications has been stymied. By combining multi-layer soft-lithography with shape memory alloys (SMA), we demonstrate electronically activated microfluidic components such as valves, pumps, latches and multiplexers, that are assembled on printed circuit boards (PCBs). Thus, high density, electronically controlled microfluidic chips can be integrated alongside standard opto-electronic components on a PCB. Furthermore, we introduce the idea of microfluidic states, which are combinations of valve states, and analogous to instruction sets of integrated circuit (IC) microprocessors. Microfluidic states may be represented in hardware or software, and we propose a control architecture that results in logarithmic reduction of external control lines. These developments bring us closer to building microfluidic circuits that resemble electronic ICs both physically, as well as in their abstract model

Forestry Crane with Electrohydraulic Flow-on-Demand System

The major issue developing sophisticated hydraulic systems is to significantly improve the energy efficiency without sacrificing the ease of control and operability. The present paper illustrates the upgrade of a mobile forestry crane from a hydraulic-mechanical Load-Sensing system to an innovative electrohydraulical Flow-on-Demand system

Snowmelt and slush avalanches / slushflows in nothern mountains, Sweden. A video presentation.

A video of 15 minutes duration reviews different cases of slushflows in May-June 1995 and their behaviour during release and downslope propagation. Slushflow dynamics are compared with other types of mass movement

"Learning Science Is About Facts and Language Learning Is About Being Discursive"-An Empirical Investigation of Students' Disciplinary Beliefs in the Context of Argumentation

Argumentation is considered crucial in numerous disciplines in schools and universities because it constitutes an important proficiency in peoples' daily and professional lives. However, it is unclear whether argumentation is understood and practiced in comparable ways across disciplines. This study consequently examined empirically how students perceive argumentation in science and (first) language lessons. Specifically, we investigated students' beliefs about the relevance of discourse and the role of facts. Data from 3,258 high school students from 85 German secondary schools were analyzed with multigroup multilevel structural equation modeling in order to disentangle whether or not differences in argumentation across disciplines exist and the extent to which variation in students' beliefs can be explained by gender and school track. Results showed that students perceived the role of facts as highly relevant for science lessons, whereas discursive characteristics were considered significantly less important. In turn, discourse played a central role in language lessons, which was believed to require less knowledge of facts. These differences were independent of students' gender. In contrast, school track predicted the differences in beliefs significantly. Our findings lend evidence on the existence of disciplinary school cultures in argumentation that may be the result of differences in teachers' school-track-specific classroom practice and education. Implications in terms of a teacher's role in establishing norms for scientific argumentation as well as the impact of students' beliefs on their learning outcomes are discussed

Machine Diagnostics in scope of the LaSeKo Project

Agricultural processes have to comply with ecological, economical and political demands. Especially the tracing of food is important for consumer protection. At the same time reducing costs is necessary for farmers to be competitive. Machine up time is a critical factor, especially in processes that are reliant on short, whether-depending harvesting slots. Based on a mobile electronic system, the project consortium of the LaSeKo-Project is developing an autonomous agricultural communication system for the traceability of crops and harvesting batches that simultaneously enables for online machine diagnostics and a remote maintenance concept