Special Coverage

Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines
Vibration Tables Shake Up Aerospace and Car Testing
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

Analytic Technique for Separation of Cochannel FM Signals

In the absence of noise, two signals can be separated perfectly.

A digital processing technique for separating two cochannel frequency-modulation (FM) signals involves a partial algebraic solution that gives the phases of the two signals to within one of two possibilities, plus the use of a two-state trellis algorithm to trace the most likely correct sequence of possibilities. Other techniques for separating cochannel FM signals do not yield perfect separation under any circumstances; however, the present technique can yield perfect separation in the absence of noise.

Posted in: Briefs, Information Sciences, Mathematical models, Communication protocols

Tribological Characterization of Solid Surfaces

Reports labeled as chapters 2, 3, 4, 7, 8, 9, and 10 of a NASA technical memorandum that addresses topics in tribology have been compiled into a document that emphasizes those aspects of the subject matter that pertain to chemical-vapor-deposited (CVD) diamond and diamond-like films. The titles of the reports are the following: "Solid Lubrication Fundamentals and Applications [—] Characterization of Solid Surfaces," "Solid Lubrication Fundamentals and Applications [—] Properties of Clean Surfaces: Adhesion, Friction, and Wear," "Solid Lubrication Fundamentals and Applications [—] Properties of Contaminated Surfaces: Adhesion, Friction, and Wear," "Aerospace Mechanisms and Tribology Technology: Case Studies," "Structures and Mechanical Properties of Natural and Synthetic Diamonds," "Chemical-Vapor-Deposited Diamond Film," and "Surface Design and Engineering Toward Wear-Resistant, Self-Lubricant Diamond Films and Coatings." The collection is accompanied by a single-page preface that summarizes the economic and technological significance of CVD diamond as a solid lubricant and as a mechanically, chemically protective coating material.

Posted in: Briefs, TSP, Materials, Coatings, colorants, and finishes, Materials properties, Tribology, Wear

Small Balloons for Local Aerial Exploration of Mars

A report proposes the use of lightweight balloon-borne instrumentation systems for exploration in the vicinity of a lander on the surface of Mars. Each system would comprise instrumentation with a mass of about 0.2 kg and a balloon with a mass of about 0.8 kg and volume of about 50 m3. The balloons would be inflated with H2 or He by use of an apparatus based on the automatic inflation equipment used on Earth to launch weather balloons. Of course, the apparatus would incorporate special design features to ensure successful launches in the thin, cold, windy Martian atmosphere and to minimize damage to balloons on the rock-strewn Martian terrain.

Posted in: Briefs, TSP, Physical Sciences, Elastomers, Gases, Durability, Spacecraft, Unmanned aerial vehicles

Using Electromagnetic Drag on Tethers To De-Orbit Spacecraft

Two papers propose the use of electrically conductive tethers to remove spent or dysfunctional spacecraft from orbit around the Earth in order to reduce the hazard of orbital debris. In comparison with onboard rockets, these tethers would be more cost-effective, more reliable, and less massive. Once deployed, a tether would not require an onboard power supply. Both ends of the tether would be equipped with electrodes to make electrical contact with the ionosphere and thereby complete an electrical circuit. The orbital motion of the tether across the Earth's magnetic field would induce an electrical current in the tether. The consequent electrical heating of the tether would gradually dissipate the orbital kinetic energy of the spacecraft. It has been estimated that a typical spacecraft could be removed from orbit in weeks or months in this way, whereas the satellite might otherwise remain in orbit for years or even centuries.

Posted in: Briefs, Mechanical Components, Mechanics, Electrical systems, Conductivity, Entry, descent, and landing, Satellites

Apparatus and Technique for Measuring Distance Between Axles

A combination of optoelectronic modules takes much of the tedium out of the measurements.

An optoelectronic apparatus and a technique for its operation have been developed to facilitate and accelerate the measurement of distances of the order of tens of feet to within error limits of about ±1/8 in. (about 3 mm). In the original application, the distance to be measured [≈ 66 ft (≈20 m)] is that between the axes of rotation of the front and rear tires of the space shuttle orbiter as it rests in a ground-based processing facility. Previously, this distance was determined in a tedious procedure that involved measurements of component horizontal distances between floor points found by dropping plumb bobs. (This distance is used, along with other measurements, to locate the center of gravity of the orbiter.) The apparatus and technique could also be used for similar purposes in other settings; for example, to measure perpendicular distances between wall frames in situations in which tape measures cannot be used, to establish fence lines, or to lay out football grids.

Posted in: Briefs, TSP, Physical Sciences, Measurements, Axles, Test equipment and instrumentation, Test procedures, Reusable launch vehicles and shuttles

Miniature, Low-Power, Digital, Wireless Electronic Camera

This portable unit can be programmed to operate in a variety of modes.

A portable, battery-powered camera unit contains a programmable digital camera that is implemented on a single chip utilizing active-pixel-sensor (APS) technology, plus circuitry for digital radio communication between the camera and a base station. A laboratory-bench-top version of this digital wireless camera has been demonstrated to function as intended, and continuing development efforts are directed toward miniaturization (see figure). The fully miniaturized unit is intended to serve as a prototype of low-power, long-battery-life, portable, digital, wireless electronic cameras for such applications as surveillance in military and civilian settings, home security, and remote monitoring of babies.

Posted in: Briefs, TSP, Electronics & Computers, Downsizing, Integrated circuits, Optics, Surveillance, Wireless communication systems

Improved Accelerated Corrosion Testing of Zinc-Rich Primers

Electrochemical impedance spectroscopy is used in conjunction with atmospheric exposure.

An improved method of accelerated testing reduces the time needed to analyze the abilities of zinc-rich primers to protect steel substrates against corrosion in a seacoast environment. In this method, specimens are placed in racks where they are exposed to the environment. From time to time, the specimens are brought to a laboratory, where they are tested by electrochemical impedance spectroscopy (EIS). The specimens are then returned to the racks for further exposure.

Posted in: Briefs, TSP, Materials, Spectroscopy, Corrosion resistant alloys, Steel, Zinc alloys, Test procedures, Marine vehicles and equipment

Wearable Sensor Patches for Physiological Monitoring

Noninvasive sensors resembling adhesive bandages would be interrogated by nearby hand-held units.

Wearable sensor patches — miniature biotelemetric units — have been proposed for use in measuring temperature, heart rate, blood pressure, and possibly other physiological parameters. The sensor patches would be small and could be mass-produced inexpensively by use of state-of-the-art techniques for batch fabrication of integrated circuits and microelectromechanical systems.

Posted in: Briefs, TSP, Bio-Medical, Medical

Rayleigh-Scattering Measurement of Temperature and Velocity

Further development of the temperature-measurement capability is needed.

Figure 1 schematically depicts an experimental setup in which Rayleigh scattering from molecules of a flowing gas is used to measure the temperature and one component of the velocity of the gas. The Rayleigh-scattering apparatus in this setup is capable of operation in the harsh environments (varying temperatures and intense vibrations and sound) commonly found in aerospace test facilities.

Posted in: Briefs, TSP, Physical Sciences, Measurements, Gases, Test equipment and instrumentation, Thermal testing

Integrated Optical Voltage-Measuring Apparatus

This apparatus can measure high voltage safely and remotely.

An integrated optical voltage-measuring apparatus based on a Mach-Zehnder interferometer has been designed and constructed. The main feature of this apparatus is that optical fibers link part of it to an optical sensor head placed at the source of the voltage to be measured, whether the source be a space-based power distribution control system or a ground-based high-voltage system. The optical fibers and sensor of this apparatus are immune to electromagnetic interference. This apparatus could be highly suitable for use in automatic control of space-based or aeronautical power-management and power-distribution systems. Potential ground-based commercial applications include measuring voltages and electric fields in electrical power systems, physiological monitoring and recording, measurements of pulsed power, and testing for electromagnetic compatibility.

Posted in: Briefs, Electronics & Computers, Measurements, Electromagnetic compatibility, Fiber optics, High voltage systems, Integrated circuits, Sensors and actuators

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