Special Coverage

Lightweight, Flexible Thermal Protection System for Fire Protection
High-Precision Electric Gate for Time-of-Flight Ion Mass Spectrometers
Polyimide Wire Insulation Repair System
Distributed Propulsion Concepts and Superparamagnetic Energy Harvesting Hummingbird Engine
Wet Active Chevron Nozzle for Controllable Jet Noise Reduction
Magnetic Relief Valve
Active Aircraft Pylon Noise Control System
Unmanned Aerial Systems Traffic Management

Nanophase Nickel-Zirconium Alloys for Fuel Cells

Corrosion resistance can be achieved at lower cost. Nanophase nickel- zirconium alloys have been investigated for use as electrically conductive coatings and catalyst supports in fuel cells. Heretofore, noble metals have been used because they resist corrosion in the harsh, acidic fuel-cell interior environments. However, the high cost of noble metals has prompted a search for less-costly substitutes.

Posted in: Briefs, TSP, Materials


Vacuum Packaging of MEMS With Multiple Internal Seal Rings

Each internal seal ring would be part of an electrical feed-through. A proposed method of design and fabrication of vacuum-packaged microelectromechanical systems (MEMS) and of individual microelectromechanical devices involves the use of multiple internal seal rings (MISRs) in conjunction with vias (through holes plated with metal for electrical contacts). The proposed method is compatible with mass production in a wafer-level fabrication process, in which the dozens of MEMS or individual microelectromechanical devices on a typical wafer are simultaneously vacuum packaged by bonding a capping wafer before the devices are singulated (cut apart by use of a dicing saw). In addition to being compatible with mass production, the proposed method would eliminate the need for some complex and expensive production steps and would yield more reliable vacuum seals.

Posted in: Briefs, TSP, Manufacturing & Prototyping


Fault-Tolerant Coding for State Machines

State machines can be rendered immune to single-event upsets. Two reliable fault-tolerant coding schemes have been proposed for state machines that are used in field-programmable gate arrays and application-specific integrated circuits to implement sequential logic functions. The schemes apply to strings of bits in state registers, which are typically implemented in practice as assemblies of flip-flop circuits. If a single-event upset (SEU, a radiation- induced change in the bit in one flip-flop) occurs in a state register, the state machine that contains the register could go into an erroneous state or could “hang,” by which is meant that the machine could remain in undefined states indefinitely. The proposed fault-tolerant coding schemes are intended to prevent the state machine from going into an erroneous or hang state when an SEU occurs.

Posted in: Briefs, TSP, Information Sciences


How a Supercomputing Innovation Accelerated a Business

Larry Lukis Founder and CTO Proto Labs, Inc. Maple Plain, MN Proto Labs is a quick-response custom manufacturer that provides design engineers with prototypes of plastic parts faster than anyone in the world. Our Protomold division produces prototypes (and short run production parts) by injection molding, and our First Cut Prototype division produces prototypes by CNC machining plastic stock.

Posted in: Articles


Compact Two-Dimensional Spectrometer Optics

This unit would feature coarse and fine resolution along two orthogonal axes. The figure is a simplified depiction of a proposed spectrometer optical unit that would be suitable for incorporation into a remote-sensing instrumentation system. Relative to prior spectrometer optical assemblies, this unit would be compact and simple, largely by virtue of its predominantly two-dimensional character.

Posted in: Briefs, TSP, Physical Sciences


Graphite/Cyanate Ester Face Sheets for Adaptive Optics

Unlike glass face sheets, these would be nearly unbreakable.It has been proposed that thin face sheets of wide-aperture deformable mirrors in adaptive-optics systems be made from a composite material consisting of cyanate ester filled with graphite. This composite material appears to offer an attractive alternative to low-thermal-expansion glasses that are used in some conventional optics and have been considered for adaptive- optics face sheets.

Posted in: Briefs, Physical Sciences


Protecting AC Motors From Destructive Shaft Currents

The use of variable-frequency drives (VFDs) to control AC motors has increased dramatically in recent years. In addition to low operating cost and high performance, they save energy. Today, the challenge facing system designers and engineers is to minimize damage to AC motors from shaft current.

Posted in: Articles, Motion Control


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