Carbon Nanotube Purification

Development of carbon nanotubes (CNTs), including single-wall and multi-wall nanotubes and nanofibers, into useful devices requires fabrication of CNTs that are relatively free from process residues such as amorphous carbon and metallic particles that are not part of a CNT array grown on a (coated) substrate. Conventional techniques for removal of amorphous carbon and other residues often use one of several techniques. One technique uses post-growth thermal or plasma cleaning of the amorphous carbon with Ox (x=2), which non-selectively attacks the CNT material as well as the amorphous carbon. Metal contaminants are removed using an acid bath, which is again a non-selective process and requires disposal of the strong acids and contaminant removal byproducts. A second technique uses certain toxic gases, such as halogens, to remove the amorphous carbon and other residues. This approach requires disposal of one or more hazardous substances and often requires many hours to complete. A third approach requires holding the amorphous carbon and CNTs in a heated Ox atmosphere for several hours, in order to limit the damage to the CNTs.

Posted in: Briefs, TSP, Mechanical Components, Fabrication, Nanomaterials, Quality assurance, Quality assurance
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Metal Stamping Design Guidelines

Metal Stamping provides an economical way to produce quantities of parts that can possess many qualities, including strength, durability, wear resistance, good conductive properties, and stability. In this paper, we are sharing some ideas that can help you design a part that optimizes all the features that the metal stamping process offers.

Posted in: Briefs, TSP, Aeronautics, Manufacturing & Prototyping, Materials, Mechanical Components, Design processes, Stamping, Metals, Parts
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Deployable Perimeter Truss with Blade Reel Deployment Mechanism

Solar sail technology depends heavily on the total surface area of the sail. In other words, minimizing mass and volume of its support structure is the main objective, particularly when it comes to launch configuration, i.e. mass, volume constraints, etc. There is a need to develop a low-cost concept of a deployable support structure that can stow in the EELV Secondary Payload Adapter (ESPA) volume, and carries as much sail material as possible. This structure must then be able to deploy the sail material out, and provide the surface area needed.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Solar energy, Packaging, Lightweighting, Spacecraft
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NEO Hunter Seeker Micro-Spacecraft and Mission Concept

The area of research known as “Planetary Defense” is largely concerned with identifying and tracking asteroids that could impact Earth. The vast majority of asteroids that pose such a risk are known as “Near Earth Asteroids/Objects” or NEAs and NEOs. Some of them are unknown, un-cataloged, and untracked, but are presumed to orbit in Earth-like orbits, and periodically cross Earth’s orbit in a possibly threatening manner.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Imaging, Imaging and visualization, Imaging, Imaging and visualization, Particulate matter (PM), Spacecraft
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Multipath, Multistage, Erosion-Resistive Valve for Downhole Flow Control

Multipath, multistage, erosion-resistant flow control valves have been developed that can sustain the extremely high pressure of deep oil wells. Fitting in the restricted available space and operating using limited power with a long lifetime are challenges for choke valves in the downhole environment of oil wells. These valves must control the flow rate from high-pressure oil reservoirs in the presence of fluids that have non-zero sand concentrations. This design consists of a digitized flow control valve with multipath and multistage pressure reduction structures. Specifically, the valve is configured as a set of parallel flow paths from the inlet to the outlet.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Drilling, Valves, Mining vehicles and equipment
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Passive Close-Off Feature for Sample Acquisition and Retention

The current coring bit and percussive drilling style works very well for strong rocks; however, when coring into weak, crumbling rock, the core tends to break apart and simply fall out of the bit. These rocks, powder, and other debris can have useful information that is lost when they fall out of the bit after the core has been made, as there is no retention feature in place. A retention mechanism for coring into weak rocks was developed.

Posted in: Briefs, TSP, Mechanical Components, Mining vehicles and equipment
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Piezoelectric-Actuated Cryogenic Thermodynamic Vent Valve

Cryogenic fluid control valves require actuation that controls the geometric position of the orifice in a thermally stable manner. Traditional actuator devices may have various materials used in their construction that have varying CTEs (coefficients of thermal expansion) and therefore may shift (expand or contract) relative to the reference mounting points on the valve body. This leads to a lack of valve orifice control and leakage in the valve. To provide a more thermally stable control valve for cryogenic fluids, Dynamic Structures and Materials LLC (DSM LLC) provided a piezoelectric ceramic-driven actuation system on a cryogenic thermodynamic vent system (TVS) valve.

Posted in: Briefs, TSP, Mechanical Components, Sensors and actuators, Sensors and actuators, Thermodynamics, Thermodynamics, Ceramics, Valves
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Decelerator System Simulation (DSS)

Lyndon B. Johnson Space Center, Houston, Texas

The Crew Exploration Vehicle Parachute Assembly System (CPAS) project conducts computer simulations to verify that requirements on flight performance, parachute loads, and terminal rate of descent are met. The objective of this work was to obtain a high-fidelity simulation of Orion crew capsule flight test vehicles during parachute flight.

Posted in: Briefs, TSP, Mechanical Components, Computer simulation, Entry, descent, and landing, Spacecraft
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Miniature, Multi-Functional, Self-Braking Vehicle

This vehicle is actuated by piezoelectric stacks through the fuselage walls.

NASA’s Jet Propulsion Laboratory, Pasadena, California

A novel, miniature, low-mass vehicle has been created that is driven by piezoelectric stacks and a resonance structure. Preliminary tests on similar mechanisms that are used to transmit electrical power across the wall showed efficiencies of the order of 90%. The transmitted mechanical power, and signals through metallic walls using the direct and indirect piezoelectric effects in similar motors, is of the order of 50%. The transmitted power is generated inside the vehicle body, and the mechanism is applicable to any robotic system that may require an ambulation of locomotion mechanism such as a rover, a miniature vehicle, a crawler, or a flying device.

Posted in: Briefs, TSP, Mechanical Components, Power electronics, Power electronics, On-board energy sources, Robotics, Nanotechnology
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Pulse-Echo Probe Mounting Fixture for Blind Alignment on Pipes

The probe and its mounting fixture are critical parts of the health monitoring of steam pipes. A high-temperature, piezoelectric transducer generates and receives ultrasonic waves, and the probe has to transmit the wave normal to the pipe surface. The mounting fixture is designed to allow for alignment of the probe even without a reference reflection, and thus enables blind alignment. In order to allow aligning of the probe normal to the surface of potential water condensation, and to secure intimate contact to the pipe surface, a novel mounting fixture was conceived and developed.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Mountings
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