Efficient Two-Dimensional Solution Methods for the Navier-Stokes Equations

ARC2D is a computational fluid dynamics (CFD) program for two-dimensional airfoil and simply connected geometries. The program uses implicit finite-difference techniques to solve two-dimensional Euler equations and Navier-Stokes equations. It is based on the Beam and Warning implicit approximate factorization algorithm in generalized coordinates, in a variety of block or diagonal forms. The methods are either time-accurate (e.g., dual-time-stepping or Runge-Kutta methods) or accelerated non-time-accurate steady-state schemes. The evolution of the solution through time is physically realistic; good solution accuracy is dependent on mesh spacing and boundary conditions.

Posted in: Briefs, Software
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High-Resolution, Coherent, Dual-Tip Scanning Probe Microscope

The scanning tunneling microscope (STM) has become one of the most powerful tools used in studying the surface structure of electrically conducting solid-state materials at an atomic resolution. Since its conception, the STM has had the greatest impact in the field of modern surface science because of its superior capability of characterizing and resolving the surface atomic structures and defects. Surface features such as atomic point defects, dislocations, and grain boundary identification can routinely be studied using a STM. Furthermore, STMs also allow the characterization of step structures at the atomic level during the processes of surface preparation and growth of semiconductors, such as epitaxial growth on semiconductor structures.

Posted in: Briefs, Photonics
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Using SysML to Model Layered System Interfaces

To produce accurate system architecture descriptions, it is essential to be able to describe interfaces between system elements at different levels of abstraction and from different perspectives at the same time. For example, the connection from system A to system B may be viewed at a high level as independent of the mechanisms that implement that flow (copper wire, free space RF, optical), and it may be useful to explore which of several of these mechanisms might be used. It is also frequently useful to analyze and constrain the problem (interface bindings) at several levels of detail (application protocols, network protocols, physical layer connections) separately, as well as in combination.

Posted in: Briefs, Software
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Multifunctional Hot Structure (HOST) Heat Shield

Traditional heat shield design isolates the functions of the thermal protection system (TPS) from the underlying load-carrying structure. This is due to the use of brittle TPS material that cannot carry the structural loads and that ablate during planetary entry. To isolate the TPS, the traditional approach has been to either bond a strain isolation pad between the TPS and structure or to design the structure significantly thick to eliminate bending loads transferred to the TPS. Adhesive is used to bond the TPS to the pad and/or structure. These bond lines can be a source of stress concentrations and manufacturing flaws.

Posted in: Briefs, Mechanical Components
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Pegasus 5.2 Software for Automated Pre-Processing of Overset CFD Grids

Pegasus software is used as a pre-processor for overset-grid Computational Fluid Dynamics (CFD) simulations. It provides the hole-cutting and connectivity information between structured overset grids. The main features of the software include automated hole-cutting algorithms, a projection scheme for fixing small discretization errors in overset surface, efficient interpolation search methods, hole-size optimization based on adding additional layers of fringe points, and an automatic restart capability. The code can run in parallel using the Message-Passing Interface (MPI) standard.

Posted in: Briefs, Software
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Fast, Sensitive Hydrogen Sensor

Hydrogen is a promising potential fuel for cars, buses, and other vehicles, and can be converted into electricity in fuel cells. It already is used in medicine and space exploration, as well as in the production of industrial chemicals and food products.

Posted in: Briefs, Sensors
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Feed Mechanism and Method for Feeding Minute Components

Electrical circuits such as printed wiring boards or hybrid microcircuits designed to utilize surface mount electrical components are commonly assembled by computer-controlled automated equipment. These machines typically use a vacuum nozzle to pick up and handle the components during assembly. Three methods are commonly used to feed surface mount components to automatic assembly equipment: tape reel feeders, linear or bowl-type vibratory feeders, or waffle-style packages.

Posted in: Briefs, Mechanical Components
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Vibration-Dampening Pedestal for MEMS

Microelectromechanical systems (MEMS) are critical devices for various highly sensitive applications; however, the development and potential fielding of these next-generation smart systems is currently impeded by the inability to satisfy the stringent performance standards for precision and control. These advanced smart systems currently suffer from severe inaccuracies caused by a critical failure of a MEMS inertial measurement unit (IMU), i.e., the angular rate sensor (ARS).

Posted in: Briefs, Mechanical Components
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Self-Healing, Self-Lubricating Tribofilm

Tribologists have developed a diamond-like film that is generated by the heat and pressure of an automotive engine. The ultra-durable, self-lubricating tribofilm — a film that forms between moving surfaces — can be made to develop self-healing, diamondlike carbon (DLC) tribofilms. The film generates itself by breaking down the molecules of the lubricating oil, and can regenerate the tribofilm as it is worn away.

Posted in: Briefs, Materials
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Fiber-Optic Environmental Radiation Dosimeter

An all-optical, fiber-optic-coupled remote radiation sensor was developed using luminescent, copper-doped quartz material. The key to the technology is the doped quartz material, which produces a luminescence signal that is directly proportional to the radiation dose.

Posted in: Briefs, Photonics
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