Tech Briefs

Software for Monitoring Performance of Other Software

Performance Logging Services (PLS) is a software utility that tracks the performance of another program in terms of statistics of timing and use of memory buffers. The monitored program must utilize either the UNIX or the VxWorks operating system. PLS can monitor performance requirements in real time and uses minimal memory and central-processing-unit (CPU) resources. It can measure software timing events with an accuracy of less than 50 µs. PLS consists of (1) a library of application-program interfaces (APIs) and (2) a performance-control-tool subprogram. The APIs are incorporated into a program to be monitored by simply compiling them with the program code. During execution, the APIs update performance statistics in shared memory, to which an external program can gain access. An operator can use the performance-control tool to gain access to the statistics, reset the statistics, and set control limits (essentially, upper and lower limiting values of statistics). The performance-control tool includes a trigger that can be used to start another program when the control limits are exceeded. Data from the triggered program is used to find the source of timing glitches and/or otherwise assist in troubleshooting when performance requirements are out of specification.

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Polymer Electrolytes for Rechargeable Lithium Batteries

Cyanoresins would be blended and complexed with Li salts. Polymeric electrolytes for rechargeable lithium-based electrochemical cells and batteries would be made by blending and complexing cyanoresins with lithium salts, according to a proposal. In particular, polymeric electrolytes for separators, carbon-composite anodes, and cathodes would be formulated from appropriate blends of different polymers that are mutually insoluble and do not chemically react with each other. As a result, each polymeric component would retain its specific desired characteristics in high-energy-density batteries that would be capable of long cycle lives and high charge/discharge rates. For example, one polymeric component could provide high ionic conductivity and charge-carrier concentration while another polymeric component would provide structural integrity. Conceivably, a lithium battery made with such materials could exhibit an energy density of 80 W×h/lb for more than 1,000 charge/discharge cycles. Batteries like this could be used in applications ranging from geosynchronous satellites to electric vehicles to small consumer electronic equipment.

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Coupled-Layer Architecture for Advanced Software for Robots

Decision-making and functional infrastructures interact at all levels of granularity. The title "Coupled Layer Architecture for Robotics Autonomy" (CLARATy) refers to a software architecture for robots that has been proposed to (1) improve the modularity of robotic-system software while (2) tightening the coupling between autonomy and control software subsystems. Whereas prior robotic architectures have typically been characterized by three layers, the CLARATy is characterized by only two layers. The CLARATy provides for interaction of decision-making and functional infrastructures at all levels of system granularity. This architecture is flexible enough to encompass research and application domains, and provides for an explicit coupling of artificial-intelligence and robotics techniques. The architecture is also implemented in an object-oriented fashion that makes it possible to leverage software design through both inheritance and aggregation, thereby eliminating the need for duplication of effort in the development of new software.

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Characteristics of Dynamics of Intelligent Systems

These characteristics are proposed as means of discriminating between living and nonliving systems. An investigation of nonlinear mathematical models of dynamics has led to the selection of characteristics that could be useful for distinguishing mathematically between the behaviors of (1) intelligent or living systems and (2) nonliving systems. As contemplated here, an intelligent or living system could range from a natural or artificial single-cell organism at one extreme to the whole of human society at the other extreme, whereas a nonliving system could be, for example, a collection of interacting particles or mechanisms. Among other findings, the investigation has revealed that living systems can be characterized by nonlinear evolution of probability distributions over different possible choices of the next steps in their motions.

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Analyzing Aeroelasticity in Turbomachines

ASTROP2-LE is a computer program that predicts flutter and forced responses of blades, vanes, and other components of such turbomachines as fans, compressors, and turbines. ASTROP2-LE is based on the ASTROP2 program, developed previously for analysis of stability of turbomachinery components. In developing ASTROP2-LE, ASTROP2 was modified to include a capability for modeling forced responses. The program was also modified to add a capability for analysis of aeroelasticity with mistuning and unsteady aerodynamic solutions from another program, LINFLX2D, that solves the linearized Euler equations of unsteady two-dimensional flow. Using LINFLX2D to calculate unsteady aerodynamic loads, it is possible to analyze effects of transonic flow on flutter and forced response. ASTROP2-LE can be used to analyze subsonic, transonic, and supersonic aerodynamics and structural mistuning for rotors with blades of differing structural properties. It calculates the aerodynamic damping of a blade system operating in airflow so that stability can be assessed. The code also predicts the magnitudes and frequencies of the unsteady aerodynamic forces on the airfoils of a blade row from incoming wakes. This information can be used in high-cycle-fatigue analysis to predict the fatigue lives of the blades.

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Manufacturing Process Management for Test

Test is critical to the board manufacturing process. Effective test ensures quality and customer satisfaction both for the OEM (original equipment manufacturer) and the CEM (contract electronics manufacturer). By isolating defects before product shipment, test minimizes returns and related costs. But test takes time, and the cost can be prohibitive.

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Improved Process for Fabricating Carbon Nanotube Probes

An improved process has been developed for the efficient fabrication of carbon nanotube probes for use in atomic-force microscopes (AFMs) and nanomanipulators. Relative to prior nanotube tip production processes, this process offers advantages in alignment of the nanotube on the cantilever and stability of the nanotube's attachment. A procedure has also been developed at Ames that effectively sharpens the multiwalled nanotube, which improves the resolution of the multiwalled nanotube probes and, combined with the greater stability of multiwalled nanotube probes, increases the effective resolution of these probes, making them comparable in resolution to single-walled carbon nanotube probes. The robust attachment derived from this improved fabrication method and the natural strength and resiliency of the nanotube itself produces an AFM probe with an extremely long imaging lifetime. In a longevity test, a nanotube tip imaged a silicon nitride surface for 15 hours without measurable loss of resolution. In contrast, the resolution of conventional silicon probes noticeably begins to degrade within minutes. These carbon nanotube probes have many possible applications in the semiconductor industry, particularly as devices are approaching the nanometer scale and new atomic layer deposition techniques necessitate a higher resolution characterization technique. Previously at Ames, the use of nanotube probes has been demonstrated for imaging photoresist patterns with high aspect ratio. In addition, these tips have been used to analyze Mars simulant dust grains, extremophile protein crystals, and DNA structure. This NASA technology is being commercialized through Convergent Science and Technology Inc. ().

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