The preparation of crystalline lactic acid

On account of its importance in intermediary metabolism, lactic acid was among the first compounds chosen in our plan, which we have described in a previous communication (1), to augment the available data on the free energies of formation of substances significant in biological chemistry. It was necessary for this purpose to obtain pure crystalline lactic acid, free of water, anhydride, and lactide. The only description in the literature of the preparation of crystalline lactic acid is that of Krafft and Dÿes (2). Table I shows that the product obtained by their method contains relatively large quantities of anhydro impurities. The subject of the present communication is the description of a method which yields the active isomers of lactic acid in a crystalline state, free of water, anhydride, and lactide, supplemented by the description of two methods of separating the active forms from the commercial syrup (1). Lactic acid commercially available at present either is in the form of the U.S.P. syrup, which usually exhibits a low optical activity corresponding to the excess it happens to contain, which is variable, of one or the other optical isomer, or is the expensive zinc sarcolactate. The methods described below now make it possible to obtain easily and quickly and at low cost large quantities of both active isomers in a relatively high degree of purity

Evaluation of a low cost solid-state accelerometer as a distance measuring sensor for vehicle positioning system

This paper describes an evaluation of a low cost, solid state accelerometer as a distance-measuring device. Kalman filter was applied to reduce random noise existing in the sensor. The random bias drift of the accelerometer was found to be 2.5 mg. The accelerometer was moved back and forth eight times for a distance of 40 cm with an acceleration of 10 m/s2 and the distance error accumulated +1.55 cm. The bias drift rate due to temperature was 0.108 μg/s when the accelerometer was placed at room temperature. The performance shows that the device is suitable for short duration distance measurement and may act as a complementary sensor to the GPS during signal blockage or between periodical absolute position updates.published_or_final_versio

The optical depth of white-light flare continuum

The white-light continuum emission of a solar flare remains a puzzle as regards its height of formation and its emission mechanism(s). This continuum, and its extension into the near UV, contain the bulk of the energy radiated by a flare, and so its explanation is a high priority. We describe a method to determine the optical depth of the emitting layer and apply it to the well-studied flare of 2002 July~15, making use of MDI pseudo-continuum intensity images. We find the optical depth of the visible continuum in all flare images, including an impulsive ribbon structure to be small, consistent with the observation of Balmer and Paschen edges in other events

Mixed-Norm Multi-Objective Robust Controller Applied to a Very Flexible Aircraft

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90725/1/AIAA-2011-6256-879.pd

Application of Robust Control Design Techniques to the Aeroservoelastic Design Optimization of a Very Flexible UAV Wing

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83662/1/AIAA-2010-9123-917.pd

Optical wireless based on high brightness visible LEDs

This paper is on a novel use of lighting or signaling devices constructed by light-emitting diodes (LEDs). The idea is on their concurrent use for simultaneous signaling and communications. The visible light from LEDs can be modulated and encoded with audio or data signal. Hence, an LED indicator lamp or traffic light can become an information broadcasting device. Such a system made up of high brightness visible LEDs can provide the function of open space, wireless broadcasting of audio or data signal. An implemented system with experimental results is shown. A portable receiver is designed to demodulate the optically transmitted information. The distance for audio transmission of an LED traffic light can reach over 20m. The optical link employs intensity modulation with direct detection. The system is limited to line-of-sight communications. However, this concurrent use of LEDs will open up many new applications.published_or_final_versio