Special Coverage

Supercomputer Cooling System Uses Refrigerant to Replace Water
Computer Chips Calculate and Store in an Integrated Unit
Electron-to-Photon Communication for Quantum Computing
Mechanoresponsive Healing Polymers
Variable Permeability Magnetometer Systems and Methods for Aerospace Applications
Evaluation Standard for Robotic Research
Small Robot Has Outstanding Vertical Agility
Smart Optical Material Characterization System and Method
Lightweight, Flexible Thermal Protection System for Fire Protection

Multiple-Path-Length Optical Absorbance Cell

Wide dynamic range is provided for measuring widely different concentrations of CDOM. An optical absorbance cell that offers a selection of multiple optical path lengths has been developed as part of a portable spectrometric instrument that measures absorption spectra of small samples of water and that costs less than does a conventional, non-portable laboratory spectrometer. The instrument is intended, more specifically, for use in studying colored dissolved organic matter (CDOM) in seawater, especially in coastal regions. Accurate characterization of CDOM is necessary for building bio-optical mathematical models of seawater. The multiple path lengths of the absorption cell afford a wide range of sensitivity needed for measuring the optical absorbances associated with the wide range of concentrations of CDOM observed in nature.

Posted in: Briefs, Physical Sciences, Fiber optics, Spectroscopy, Waveguides, Water


Model of a Fluidized Bed Containing a Mixture of Particles

Predictions thus far are in reasonable agreement with experimental data. A mathematical model has been developed for use in analyzing the dynamics of an isothermal, non-chemically-reacting mixture of particles in a bubbling fluidized bed. Although the model has generic validity, it is intended, more specifically, to be applied to a fluidized bed that contains a mixture of sand and biomass particles, fluidized by steam. The model includes components in common with the models described in “Model of Pyrolysis of Biomass in a Fluidized-Bed Reactor” (NPO-20708), NASA Tech Briefs, Vol. 25, No. 6 (June 2001), page 59 and “Multiphase-Flow Model of Fluidized-Bed Pyrolysis of Biomass” (NPO-20789), NASA Tech Briefs, Vol. 26, No. 2 (February 2002), page 56.

Posted in: Briefs, TSP, Physical Sciences


Refractive Secondary Concentrators for Solar Thermal Systems

Concentration ratios as high as 104 and operating temperatures >2,000 K are anticipated. High-throughput, non-imaging, secondary concentrating optics that utilize refraction and total internal reflection are undergoing development for use in conjunction with advanced primary solar concentrators to provide solar thermal energy for space applications. This development is prompted by (1) a need to concentrate sunlight by factors of as much as 104 to satisfy design and operating requirements for some advanced solar thermal systems and (2) the impracticality of fabricating primary concentrators with sufficient precision to afford such high concentration ratios by themselves. Figure 1 illustrates the operation of a refractive secondary concentrator.

Posted in: Briefs, TSP, Physical Sciences, Optics, Solar energy


Cold Flow Calorimeter

This apparatus can measure a rapidly varying heat-transfer coefficient. The cold flow calorimeter is an apparatus for measuring a possibly rapidly varying heat-transfer coefficient on a surface. The cold flow calorimeter includes (1) a small strain gauge bonded to a small, thin steel shim that is placed on the surface of interest and (2) a circuit that controls the electric power supplied to the strain gauge to keep the strain-gauge grid at a constant temperature [e.g., 150 °F (≈66 °C)]. The instantaneous value of the heattransfer coefficient is deduced from the instantaneous power required to maintain the constant temperature. The heat-transfer coefficient measurable by use of this apparatus can range from values characteristic of natural convection to values as large as about 1,000 Btu/(ft·h·°R) [≈1.7 kW/(m·K).

Posted in: Briefs, Physical Sciences, Heat transfer, Test equipment and instrumentation


Electrochemical Systems Generate Ozone and Ozonated Water

The only inputs needed are electric energy and mildly pressurized water. Improved electrochemical systems for generating ozone (in gaseous form and/or dissolved in water) have been invented for use in disinfection and in industrial processes in which the unique, highly oxidizing chemical properties of ozone are needed. More accurately, these systems generate oxygen along with high (relative to prior systems) concentrations of ozone and, optionally, with hydrogen as a byproduct. These systems contain no pumps and very few moving or wearing components, and the only inputs needed to operate these systems are electric energy and water supplied at mild pressure. Moreover, these systems can readily be designed and constructed on any scale (e.g., from research laboratory to industrial) to suit a wide variety of applications.

Posted in: Briefs, Physical Sciences


Solar Simulator for a Portable Solar-Absorptance Instrument

The principal advantages are portability and accurate normalized AM0 spectrum. A special-purpose solar simulator includes (1) a tungsten lamp that serves as a gray-body radiator with a temperature of 3,200 K and (2) a mosaic of filters such that the filtered lamp output has the same normalized spectral irradiance as that of sunlight outside the atmosphere of the Earth. This solar simulator is intended for use as the illuminator in a portable instrument that measures solar absorptances and total emittances of samples of materials.

Posted in: Briefs, Physical Sciences, Sun and solar, Test equipment and instrumentation


Portable Instrument Detects Very Dilute Airborne Organics

This instrument offers an attractive alternative to GC/MS. A small, lightweight, low-power instrument, denoted a proton-transferreaction/ ion-mobility spectrometer (PTR-IMS) has been developed for detecting airborne organic compounds at concentrations in the sub-parts-per-billion range. Instruments like this one could be used on distant planets (such as Mars) to search for trace organic compounds indicative of life as well as numerous potential terrestrial uses: A few examples include medical applications (e.g., analyzing human breath to detect compounds associated with certain deadly diseases such as lung cancer and cirrhosis of the liver), lawenforcement applications (detecting airborne traces of explosives and drugs), environmental monitoring (detecting airborne pollutants and toxins), and military applications (detecting chemical warfare agents).

Posted in: Briefs, TSP, Physical Sciences, Spectroscopy, Air pollution, Volatile organic compounds, Diagnosis, Chemicals, Materials identification


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