Tech Briefs

Partial Automation of Requirements Tracing

Requirements Tracing on Target (RETRO) is software for after-the-fact tracing of textual requirements to support independent verification and validation of software. RETRO applies one of three user-selectable information-retrieval techniques: (1) term frequency/inverse document frequency (TF/IDF) vector retrieval, (2) TF/IDF vector retrieval with simple thesaurus, or (3) keyword extraction. One component of RETRO is the graphical user interface (GUI) for use in initiating a requirements-tracing project (a pair of artifacts to be traced to each other, such as a requirements spec and a design spec). Once the artifacts have been specified and the IR technique chosen, another component constructs a representation of the artifact elements and stores it on disk.

Posted in: Briefs, TSP, Software, CAD / CAM / CAE, CAD, CAM, and CAE, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Automation, Certification

Automated Synthesis of Architectures of Avionic Systems

The Architecture Synthesis Tool (AST) is software that automatically synthesizes software and hardware architectures of avionic systems. The AST is expected to be most helpful during initial formulation of an avionic-system design, when system requirements change frequently and manual modification of architecture is time-consuming and susceptible to error. The AST comprises two parts: (1) an architecture generator, which utilizes a genetic algorithm to create a multitude of architectures; and (2) a functionality evaluator, which analyzes the architectures for viability, rejecting most of the non-viable ones. The functionality evaluator generates and uses a viability tree — a hierarchy representing functions and components that perform the functions such that the system as a whole performs system-level functions representing the requirements for the system as specified by a user. Architectures that survive the functionality evaluator are further evaluated by the selection process of the genetic algorithm. Architectures found to be most promising to satisfy the user’s requirements and to perform optimally are selected as parents to the next generation of architectures. The foregoing process is iterated as many times as the user desires. The final output is one or a few viable architectures that satisfy the user’s requirements.

Posted in: Briefs, TSP, Software, CAD / CAM / CAE, CAD, CAM, and CAE, Architecture, Avionics, Architecture, Avionics, Systems engineering

SSRL Emergency Response Shore Tool

The SSRL Emergency Response Shore Tool (wherein “SSRL” signifies “Smart Systems Research Laboratory”) is a computer program within a system of communication and mobile-computing software and hardware being developed to increase the situational awareness of first responders at building collapses. This program is intended for use mainly in planning and constructing shores to stabilize partially collapsed structures. The program consists of client and server components, runs in the Windows operating system on commercial off-the-shelf portable computers, and can utilize such additional hardware as digital cameras and Global Positioning System devices.

Posted in: Briefs, TSP, Software, Computer software / hardware, Computer software and hardware, Global positioning systems, Global positioning systems (GPS), Computer software / hardware, Computer software and hardware, Global positioning systems, Global positioning systems (GPS), Hazards and emergency management, Hazards and emergency operations, Construction vehicles and equipment

Four-Quadrant Analog Multipliers Using G4-FETs

Devices with independently biased multiple inputs are exploited to simplify multiplier circuits.

Theoretical analysis and some experiments have shown that the silicon-on-insulator (SOI) 4-gate transistors known as G4-FETs can be used as building blocks of four-quadrant analog voltage multiplier circuits. Whereas a typical prior analog voltage multiplier contains between six and 10 transistors, it is possible to construct a superior voltage multiplier using only four G4-FETs.

Posted in: Briefs, TSP, Semiconductors & ICs, Architecture, Transistors, Architecture, Transistors, Semiconductors, Silicon alloys

Carbon-Nanotube-Carpet Heat-Transfer Pads

The compliance and high longitudinal thermal conductivity of carbon nanotubes are exploited.

Microscopic thermal-contact pads that include carpetlike arrays of carbon nanotubes have been invented for dissipating heat generated in integrated circuits and similarly sized single electronic components. The need for these or other innovative thermal-contact pads arises because the requisite high thermal conductances cannot be realized by scaling conventional macroscopic thermal-contact pads down to microscopic sizes. Overcoming limitations of conventional thermal-contact materials and components, the carbon-nanotube thermal-contact pads offer the high thermal conductivities needed to accommodate the high local thermal power densities of modern electronic circuits, without need for large clamping pressures, extreme smoothness of surfaces in contact, or gap-filling materials (e.g., thermally conductive greases) to ensure adequate thermal contact. Moreover, unlike some conventional thermal-contact components, these pads are reusable.

Posted in: Briefs, TSP, Materials, Heat transfer, Heat transfer, Conductivity, Nanomaterials

Wholly Aromatic Ether-Imides as n-Type Semiconductors

Some of the compounds exhibit promising electron-transport properties.

Some wholly aromatic ether-imides consisting of rod-shaped, relatively-low-mass molecules that can form liquid crystals have been investigated for potential utility as electron-donor-type (n-type) organic semiconductors. It is envisioned that after further research to improve understanding of their physical and chemical properties, compounds of this type would be used to make thin-film semiconductor devices (e.g., photovoltaic cells and field-effect transistors) on flexible electronic-circuit substrates.

Posted in: Briefs, TSP, Materials, Materials properties, Refractory materials, Semiconductors

Nuclear Reactor Cooling Valve Design Optimized With FEA

Finite element analysis simulated the valve’s condition following an earthquake.

Atomic Energy of Canada, Ltd., a subcontractor of Societatea Nationala Nucleoelectrica S.A. (SNN) of Romania, contracted Badger Meter to model, test, and produce a set of precision valves for Cernavoda Unit 2, the second nuclear power plant in Cernavoda, Romania. The main concern for the construction and operation of the valves was their survivability and continued functioning after enduring an earthquake. In nuclear power plants, such valves control the cooling of the nuclear reactors where continued flow of water around the nuclear core is essential for safety. After the earthquake that precipitated the eruption of Mt. Saint Helens in 1980, testing criteria for valves routinely has included their capability to ensure the safe functioning of the reactor after seismic events, at least in terms of cooling capacity.

Posted in: Briefs, Mechanical Components, Mechanics, Finite element analysis, Water, Nuclear energy, Cooling, Valves

Pulse-Flow Microencapsulation System

Microcapsules are produced continuously under controlled, sterile conditions.

The pulse-flow microencapsulation system (PFMS) is an automated system that continuously produces a stream of liquid-filled microcapsules for delivery of therapeutic agents to target tissues. Prior microencapsulation systems have relied on batch processes that involve transfer of batches between different apparatuses for different stages of production followed by sampling for acquisition of quality-control data, including measurements of size. In contrast, the PFMS is a single, microprocessor- controlled system that performs all processing steps, including acquisition of quality-control data. The quality-control data can be used as real-time feedback to ensure the production of large quantities of uniform microcapsules.

Posted in: Briefs, Manufacturing & Prototyping, Medical equipment and supplies, Production, Pharmaceuticals, Quality control, Quality control

Automated Low-Gravitation Facility Would Make Optical Fibers

A report describes a proposed automated facility that would be operated in outer space to produce high-quality optical fibers from fluoride-based glasses, free of light-scattering crystallites that form during production in normal Earth gravitation. Before launch, glass preforms would be loaded into a mechanism that would later dispense them. A dispensed preform would be melted, cooled to its glass-transition temperature rapidly enough to prevent crystallization, cooled to ambient temperature, then pushed into a preform tip heater, wherein it would be reheated to the softening temperature. A robotic manipulator would touch a fused-silica rod to the softened glass to initiate pulling of a fiber. The robot would pull the fiber to an attachment on a take-up spool, which would thereafter be turned to pull the fiber. The diameter of the fiber would depend on the pulling speed and the viscosity of the glass at the preform tip. Upon depletion of a preform, the robot would place the filled spool in storage and position an empty spool to pull a fiber from a new preform. Pulling would be remotely monitored by a video camera and restarted by remote command if a break in the fiber were observed.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Fiber optics, Fiber optics, Fabrication, Manufacturing equipment and machinery, Robotics, Glass, Spacecraft

Surface Acoustic Wave Sensor for Viscosity Measurement

Acoustic wave solid-state viscometers can be integrated into in-line, real-time monitoring and process control systems.

Viscosity is a measure of the resistance of a liquid to flow, and is an important measurement requirement in industrial process control and OEM applications. Viscosity describes the retarding force that is proportional to the rate of deformation. This so-called shear rate has units of s-1 and describes the crossstream gradient of the flow speed.

Posted in: Briefs, Physical Sciences, Computational fluid dynamics, Measurements, Sensors and actuators, Sensors and actuators, Drag

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