Tech Briefs

Predicting Rocket or Jet Noise in Real Time

Measurement data can be analyzed in real time.

A semi-empirical theoretical model and a C++ computer program that implements the model have been developed for use in predicting the noise generated by a rocket or jet engine. The computer program, entitled the Realtime Rocket and Jet Engine Noise Analysis and Prediction Software, is one of two main subsystems of the Acoustic Prediction/Measurement Tool, which comprises software, acoustic instrumentation, and electronic hardware combined to afford integrated capabilities for real-time prediction and measurement of noise emitted by rocket and jet engines. [The other main subsystem, consisting largely of acoustic instrumentation and electronic hardware, is described in “Wireless Acoustic Measurement System,” which appears elsewhere in this section.

Posted in: Briefs, Information Sciences, Prognostics, Acoustics, Noise measurement, Jet engines, Rocket engines

Computational Workbench for Multibody Dynamics

PyCraft is a computer program that provides an interactive, workbench-like computing environment for developing and testing algorithms for multibody dynamics. Examples of multibody dynamic systems amenable to analysis with the help of PyCraft include land vehicles, spacecraft, robots, and molecular models. PyCraft is based on the Spatial-Operator-Algebra (SOA) formulation for multibody dynamics. The SOA operators enable construction of simple and compact representations of complex multibody dynamical equations. Within the PyCraft computational workbench, users can, essentially, use the high-level SOA operator notation to represent the variety of dynamical quantities and algorithms and to perform computations interactively. PyCraft provides a Python-language interface to underlying C++ code. Working with SOA concepts, a user can create and manipulate Python-level operator classes in order to implement and evaluate new dynamical quantities and algorithms. During use of PyCraft, virtually all SOA-based algorithms are available for computational experiments.

Posted in: Briefs, TSP, Software, CAD, CAM, and CAE, Mathematical models, Test equipment and instrumentation

SiC Multi-Chip Power Modules as Power-System Building Blocks

Fault-tolerant power-supply systems could be constructed and expanded relatively inexpensively.

The term “SiC MCPMs” (wherein “MCPM” signifies “multi-chip power module”) denotes electronic power-supply modules containing multiple silicon carbide power devices and silicon-on-insulator (SOI) control integrated-circuit chips. SiC MCPMs are being developed as building blocks of advanced expandable, reconfigurable, fault-tolerant power-supply systems. Exploiting the ability of SiC semiconductor devices to operate at temperatures, breakdown voltages, and current densities significantly greater than those of conventional Si devices, the designs of SiC MCPMs and of systems comprising multiple SiC MCPMs are expected to afford a greater degree of miniaturization through stacking of modules with reduced requirements for heat sinking. Moreover, the higher-temperature capabilities of SiC MCPMs could enable operation in environments hotter than Si-based power systems can withstand.

Posted in: Briefs, Semiconductors & ICs, Downsizing, Integrated circuits, Semiconductor devices, Thermal management

High-Power, High-Efficiency Ka-Band Space Traveling-Wave Tube

Improved designs of critical components contribute to increased power and efficiency.

The L-3 Communications Model 999H traveling-wave tube (TWT) has been demonstrated to generate an output power of 144 W at 60-percent overall efficiency in continuous-wave operation over the frequency band from 31.8 to 32.3 GHz. The best TWT heretofore commercially available for operation in the affected frequency band is characterized by an output power of only 35 W and an efficiency of 50 percent. Moreover, whereas prior TWTs are limited to single output power levels, it has been shown that the output power of the Model 999H can be varied from 54 to 144 W.

Posted in: Briefs, Electronics & Computers, Radio equipment, Waveguides, Performance tests

Gratings and Random Reflectors for Near-Infrared PIN Diodes

Quantum efficiency would be increased.

Crossed diffraction gratings and random reflectors have been proposed as means to increase the quantum efficiencies of InGaAs/InP positive/intrinsic/ negative (PIN) diodes designed to operate as near-infrared photodetectors. The proposal is meant especially to apply to focal-plane imaging arrays of such photodetectors to be used for near-infrared imaging. A further increase in quantum efficiency near the short-wavelength limit of the near-infrared spectrum of such a photodetector array could be effected by removing the InP substrate of the array.

Posted in: Briefs, TSP, Electronics & Computers, Optics, Performance upgrades

Aerial Videography From Locally Launched Rockets

Images of an event or scene are rapidly collected, processed, and displayed.

A method of quickly collecting digital imagery of ground areas from video cameras carried aboard locally launched rockets has been developed. The method can be used, for example, to record rare or episodic events or to gather image data to guide decisions regarding treatment of agricultural fields or fighting wildfires.

Posted in: Briefs, Electronics & Computers, Data exchange, Imaging and visualization, Rocket engines, Fire fighting, Agricultural vehicles and equipment

Optically Transparent Split-Ring Antennas for 1 to 10 GHz

Advantages include ultra-wide-band operation, miniaturization, and excellent impedance matching.

Split-ring antennas made from optically transparent, electrically conductive films have been invented for applications in which there are requirements for compact antennas capable of operation over much or all of the frequency band from 1 to 10 GHz. Primary examples of such applications include wireless local-area networks and industrial, scientific, and medical (ISM) applications. These antennas can be conveniently located on such surfaces as those of automobile windows and display screens of diverse hand-held electronic units. They are fabricated by conventional printed-circuit techniques and can easily be integrated with solid-state amplifier circuits to enhance gain.

Posted in: Briefs, Electronics & Computers, Windows and windshields, Amplifiers, Antennas, Integrated circuits, Wireless communication systems, Displays

Power-Amplifier Module for 145 to 165 GHz

This module represents the highest frequency solid-state power amplifier to date.

Figure 1. The Amplifier Is Packaged in a WR5 waveguide module, with electric-field-plane alumina probes to interface the chip to the waveguide, and bypass capacitors to suppress low-frequency oscillations. The module is compact and can easily be integrated into a test system or with wafer probes.

A power-amplifier module that operates in the frequency range of 145 to 165 GHz has been designed and constructed as a combination of (1) a previously developed monolithic microwave integrated circuit (MMIC) power amplifier and (2) a waveguide module. The amplifier chip was needed for driving a high-electron-mobility- transistor (HEMT) frequency doubler. While it was feasible to connect the amplifier and frequency-doubler chips by use of wire bonds, it was found to be much more convenient to test the amplifier and doubler chips separately. To facilitate separate testing, it was decided to package the amplifier and doubler chips in separate waveguide modules. Figure 1 shows the resulting amplifier module.

Posted in: Briefs, TSP, Electronics & Computers, Amplifiers, Integrated circuits, Waveguides, Test procedures

Ice-Penetrating Robot for Scientific Exploration

A compact probe contains advanced power, instrumentation, navigation, control, and communication systems.

The cryo-hydro integrated robotic penetrator system (CHIRPS) is a partially developed instrumentation system that includes a probe designed to deeply penetrate the Europan ice sheet in a search for signs of life. The CHIRPS could also be used on Earth for similar exploration of the polar ice caps — especially at Lake Vostok in Antarctica. The CHIRPS probe advances downward by a combination of simple melting of ice (typically for upper, non-compacted layers of an ice sheet) or by a combination of melting of ice and pumping of meltwater (typically, for deeper, compacted layers). The heat and electric power for melting, pumping, and operating all of the onboard instrumentation and electronic circuitry are supplied by radioisotope power sources (RPSs) and thermoelectric converters energized by the RPSs. The instrumentation and electronic circuitry includes miniature guidance and control sensors and an advanced autonomous control system that has fault-management capabilities.

Posted in: Briefs, TSP, Electronics & Computers, Architecture, Weather and climate, Drilling, Robotics

Automated Design of Restraint Layer of an Inflatable Vessel

A Mathcad computer program largely automates the design and analysis of the restraint layer (the primary load-bearing layer) of an inflatable vessel that consists of one or more sections having cylindrical, toroidal, and/or spherical shape(s). A restraint layer typically comprises webbing in the form of multiple straps. The design task includes choosing indexing locations along the straps, computing the load at every location in each strap, computing the resulting stretch at each location, and computing the amount of undersizing required of each strap so that, once the vessel is inflated and the straps thus stretched, the vessel can be expected to assume the desired shape.

Posted in: Briefs, TSP, Software, Elastomers, Fabrics, Gases, Tensile Strength, Restraint systems

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