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

Composite Cathodes for Dual-Rate Li-Ion Batteries

A battery could have both high charge capacity and high rate capacity. Composite-material cathodes that enable Li-ion electrochemical cells and batteries to function at both high energy densities and high discharge rates are undergoing development. Until now, using commercially available cathode materials, it has been possible to construct cells that have either capability for high-rate discharge or capability to store energy at average or high density, but not both capabilities. However, both capabilities are needed in robotic, standby-power, and other applications that involve duty cycles that include long-duration, low-power portions and short-duration, high-power portions.

Posted in: Briefs, TSP, Materials, Battery cell chemistry, Energy storage systems, Lithium-ion batteries, Composite materials


Nickel-Based Superalloy Resists Embrittlement by Hydrogen

This alloy also exhibits high strength and ductility. A nickel-based superalloy that resists embrittlement by hydrogen more strongly than does nickel alloy 718 has been developed. Nickel alloy 718 is the most widely used superalloy. It has excellent strength and resistance to corrosion as well as acceptably high ductility, and is recognized as the best alloy for many high- temperature applications. However, nickel alloy 718 is susceptible to embrittlement by hydrogen and to delayed failure and reduced tensile properties in gaseous hydrogen. The greater resistance of the present nickel- based superalloy to adverse effects of hydrogen makes this alloy a superior alternative to nickel alloy 718 for applications that involve production, transfer, and storage of hydrogen, thereby potentially contributing to the commercial viability of hydrogen as a clean-burning fuel.

Posted in: Briefs, Materials, Hydrogen storage, Product development, Metallurgy, Nickel alloys


Chemical Passivation of Li⁺-Conducting Solid Electrolytes

Such passivation could enable long-life lithium rechargeable cells.Plates of a solid electrolyte that exhibits high conductivity for positive lithium ions can now be passivated to prevent them from reacting with metallic lithium. Such passivation could enable the construction and operation of high-performance, long-life lithium-based rechargeable electrochemical cells containing metallic lithium anodes. The advantage of this approach, in comparison with a possible alternative approach utilizing lithium-ion graphitic anodes, is that metallic lithium anodes could afford significantly greater energy-storage densities.

Posted in: Briefs, TSP, Materials, Battery cell chemistry, Electrolytes, Lithium, Metals


Spherical Sensor Configurations for Three-Dimensional Detecting and Tracking

Spherical Sensor Configurations (SSC) have been designed for detecting and tracking signals in three dimensions. The Spherical Sensor Configurations offer distinct advantages over contemporary imaging systems, significantly enhancing three-dimensional (3D) situational awareness. Sensor systems utilizing a spherical geometry as a foundation (Figure 1) can be designed for a variety of applications.

Posted in: Articles, Detectors, Imaging and visualization, Sensors and actuators


Improved Descent-Rate Limiting Mechanism

This braking device can be used to capture and slow a moving vehicle. An improved braking cable-payout mechanism has been developed. Like other such mechanisms, this mechanism can be used as a braking or shock-absorbing device for any of a variety of purposes — for example, enabling a person to descend from an upper floor of a burning building at a safe speed, capturing and slowing a moving vehicle, or limiting the shock load generated by opening of a parachute. Whereas other such mechanisms operate at payout speeds that vary with the length of payout, this mechanism operates at approximately constant payout speed, regardless of the length of cord that has already been paid out.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Brake lines, Braking systems, Mathematical analysis, Elastomers


Alignment-Insensitive Lower-Cost Telescope Architecture

This next-generation architecture enables construction of very large telescopes. This architecture features an active wavefront sensing and control scheme along with methods for measuring the relative positions of the primary to aft optics, such as the secondary mirror, and should enable larger and cheaper telescope architectures needed for future applications. This design overcomes the stability requirements of large telescope primary mirrors.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Mirrors, Architecture, Optics


Miniature Latching Valve

This valve remains either open or closed when power is not supplied. A miniature latching valve has been invented to satisfy a need for an electrically controllable on/off pneumatic valve that is lightweight and compact and remains in the most recently commanded open or closed state when power is not supplied. The valve (see figure) includes a poppet that is moved into or out of contact with a seat to effect closure or opening, respectively, of the flow path. Motion of the poppet is initiated by electrical heating of one of two opposing pairs of nickel/titanium shape-memory alloy (SMA) wires above their transition temperature: heated wires contract to their “remembered” length, applying tension to pull the poppet toward or away from the seat. A latch consisting mainly of a bistable Belleville washer (a conical spring) made of a hardened stainless steel operates between two stable positions corresponding to the fully closed or fully open state, holding the poppet in one of these positions when power is not applied to either pair of SMA wires.

Posted in: Briefs, Mechanical Components, Mechanics, Springs, Nickel alloys, Smart materials, Titanium alloys, Valves, Pneumatic systems


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