Keyword: Conductivity

Briefs: Materials
Nanoscale Metal Oxide Semiconductors for Gas Sensing

A report describes the fabrication and testing of nanoscale metal oxide semiconductors (MOSs) for gas and chemical sensing. This document examines the relationship between processing approaches and resulting sensor behavior. This is a core question related to a range of applications of...

Briefs: Materials

A plasma-enhanced chemical vapor deposition (PECVD) growth technique has been developed where the choice of starting substrate was found to...

Briefs: Physical Sciences
High-Sensitivity, Broad-Range Vacuum Gauge Using Nanotubes for Micromachined Cavities

A broad-range vacuum gauge has been created by suspending a single-walled carbon nanotube (SWNT) (metallic or semiconducting) in a Schottky diode format or in a bridge conductor format, between two electrically charged mesas. SWNTs are highly sensitive to...

Briefs: Electronics & Computers
Diamond Heat-Spreader for Submillimeter-Wave Frequency Multipliers

The planar GaAs Shottky diode frequency multiplier is a critical technology for the local oscillator (LO) for submillimeter-wave heterodyne receivers due to low mass, tenability, long lifetime, and room-temperature operation. The use of a W-band (75–100 GHz) power amplifier...

Briefs: Electronics & Computers

Magnetic field response sensors are a class of sensors that are powered via oscillating magnetic fields, and when electrically active,...

Briefs: Physical Sciences

Conventional thermal conductivity gauges (e.g. Pirani gauges) lend themselves to applications such as leak detectors, or in gas chromatographs for identifying various gas species. However, these...

Briefs: Physical Sciences
Instrument for Measuring Thermal Conductivity of Materials at Low Temperatures

With the advance of polymer and other non-metallic material sciences, whole new series of polymeric materials and composites are being created. These materials are being optimized for many different applications including cryogenic and low-temperature industrial...

Briefs: Software

Over 150 years ago, Faraday provided the first comprehensive scientific study on the physics of burning candles. Complex combustion driven by the rate at which gases diffuse through each other...

Briefs: Software

In 1999, NASA’s Lunar Prospector revealed concentrated hydrogen signatures detected in permanently shadowed craters at the lunar poles. While scientists have long speculated about the source of vast...

Briefs: Materials
Silica/Polymer and Silica/Polymer/Fiber Composite Aerogels

Aerogels that consist, variously, of neat silica/polymer alloys and silica/polymer alloy matrices reinforced with fibers have been developed as materials for flexible thermal-insulation blankets. In comparison with prior aerogel blankets, these aerogel blankets are more durable and less...

Briefs: Mechanical & Fluid Systems

A proposed direct-current electromagnetic pump for circulating a molten alkali metal alloy would be smaller and lighter and would demand less input power, relative to currently...

Briefs: Electronics & Computers
Technique for Performing Dielectric Property Measurements at Microwave Frequencies

A paper discusses the need to perform accurate dielectric property measurements on larger sized samples, particularly liquids at microwave frequencies. These types of measurements cannot be obtained using conventional cavity perturbation methods, particularly for...

Briefs: Mechanical & Fluid Systems
Hybrid Heat Exchangers

A hybrid light-weight heat exchanger concept has been developed that uses high-conductivity carbon-carbon (C–C) composites as the heat-transfer fins and uses conventional high-temperature metals, such as Inconel, nickel, and titanium as the parting sheets to meet leakage and structural requirements.

Briefs: Mechanical & Fluid Systems
Low-Dead-Volume Inlet for Vacuum Chamber

Gas introduction from near-ambient pressures to high vacuum traditionally is accomplished either by multi-stage differential pumping that allows for very rapid response, or by a capillary method that allows for a simple, single-stage introduction, but which often has a delayed response. Another means to...

Briefs: Electronics & Computers

A simplified load-following control scheme has been proposed for a fuel cell power system. The scheme could be used to control devices that are important parts of a fuel cell system...

Briefs: Mechanical & Fluid Systems

Long tool bits are undergoing development that can be stowed compactly until used as rock- or ground-penetrating probes actuated by ultrasonic/sonic mechanisms. These bits are...

Briefs: Physical Sciences

The figure depicts selected aspects of an apparatus for testing thermal-insulation materials for cryogenic systems at temperatures and under vacuum or atmospheric conditions representative...

Briefs: Electronics & Computers

Nanoionics-based devices have shown promise as alternatives to microelectro-mechanical systems (MEMS) and semiconductor diode devices for switching radio-frequency (RF) signals in...

Briefs: Electronics & Computers
Electrical Switching of Perovskite Thin-Film Resistors

Electronic devices that exploit electrical switching of physical properties of thin films of perovskite materials (especially colossal magnetoresistive materials) have been invented. Unlike some related prior devices, these devices function at room temperature and do not depend on externally...

Briefs: Electronics & Computers
Electrically Variable Resistive Memory Devices

Nonvolatile electronic memory devices that store data in the form of electrical-resistance values, and memory circuits based on such devices, have been invented. These devices and circuits exploit an electrically-variableresistance phenomenon that occurs in thin films of certain oxides that exhibit...

Briefs: Materials
Silicon Oxycarbide Aerogels for High-Temperature Thermal Insulation

A high-performance, silicon oxycarbide (SiOC) aerogel material is suitable for use as thermal insulation at temperatures approaching 1,200 °C. These aerogel composites were created using cost-effective and commercially available polymeric precursors (the polymethylsiloxane...

Briefs: Physical Sciences

An improved mathematical model has been developed of the time dependence of buildup or decay of electric charge in a high-resistivity (nominally insulating) material. The model is...

Briefs: Physical Sciences
Method of Heating a Foam-Based Catalyst Bed

A method of heating a foam-based catalyst bed has been developed using silicon carbide as the catalyst support due to its readily accessible, high surface area that is oxidation-resistant and is electrically conductive. The foam support may be resistively heated by passing an electric current through...

Briefs: Information Technology
Thermal Transport Model for Heat Sink Design

A document discusses the development of a finite element model for describing thermal transport through microcalorimeter arrays in order to assist in heat-sinking design. A fabricated multiabsorber transition edge sensor (PoST) was designed in order to reduce device wiring density by a factor of...

Briefs: Test & Measurement
Apparatus Measures Thermal Conductance Through a Thin Sample From Cryogenic to Room Temperature

An apparatus allows the measurement of the thermal conductance across a thin sample clamped between metal plates, including thermal boundary resistances. It allows in-situ variation of the clamping force from zero to 30 lb (133.4 N), and variation of...

Briefs: Materials

A further improvement has been made to reduce the high-temperature thermal conductivities of the aerogel-matrix composite materials described in “Improved Silica Aerogel Composite...

Briefs: Physical Sciences

Experiments and theoretical study have demonstrated the promise of all-solid-state, high-temperature electrochemical battery cells based on NiF2 as the active cathode...

Briefs: Materials

The separation of serum or plasma from whole blood is of overriding importance in clinical chemistry. In particular, many diagnostic detection reactions of blood components...

Briefs: Electronics & Computers

It is possible to synthesize a voltage-controlled negative-differential-resistance (NDR) device or circuit by use of a pair of complementary G4FETs (four-gate...