Tech Briefs

Dimensional Stabilization of Composite Space Structures

A research project has yielded progress on several fronts toward the goal of minimizing thermal and aging distortions of composite-material (specifically, polymer- matrix/graphite-fiber) outer-space structures that are required to retain precise dimensions and shapes. The achievements of this project are also applicable to terrestrial composite-material structures to the extent to which various environmental effects can be properly taken into account. Examples include effects of expansion caused by absorption of atmospheric moisture (similar to effects of purely thermal expansion) and effects of outgassing of volatile constituents of polymers (effects of out-gassing are more pronounced in the outer-space vacuum).

Posted in: Briefs, Materials
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Adaptive Deblurring of Noisy Images

An algorithm for adaptive deblurring of images has been designed to be less adversely affected by image noise than are prior deblurring algorithms. The need for this or another noise-tolerant deblurring algorithm arises as follows: For a typical imaging instrument, in which the blurring function (also known as the point-spread function) approximates a Gaussian function in the spatial-frequency domain, a simplistic spatial-frequency-domain deblurring function equal to the inverse of the blurring function magnifies the noise at high spatial frequencies. In the present adaptive deblurring algorithm, the spatial-frequency-domain deblurring function is the product of (1) the inverse of spatial-frequency-domain blurring function and (2) a smoothing or low-pass filter function denoted variously as a power window or a P-deblurring filter function (wherein "P" signifies "power"). The term "adaptive" in the name of the algorithm characterizes the process for choosing the parameters of the power window.

Posted in: Briefs, Physical Sciences
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Implementing a GPS Waveform Under the SCA

A continuing development effort focuses on implementation of a Global Positioning System (GPS) waveform under the Software Communications Architecture (SCA). [As used within the special technological discipline of the SCA, "waveform" signifies not only a waveform in the commonly understood sense of the word, but also subsystems and components for receiving and transmitting the waveform; subsystems for processing the information conveyed by the waveform; subsystems that perform ancillary communication and control services relevant to the role of the affected software-defined radio (a transmitter, receiver, or transceiver) as a node in a data-communication network; and any or all of the aforesaid information and services.] The intent is to optimize GPS services by providing position and time information as an embedded waveform within a software-defined radio (SDR), rather than using additional GPS chip sets to provide the information. It is further intended that the GPS waveform first will be used to provide position and time information in Joint Tactical Radio System (JTRS) radios. [The JTRS is a family of military SDRs, waveforms, and cryptographic algorithms designed under the SCA.] The JTRS radios are reprogrammable to run a family of special waveforms that utilize carrier frequencies from 2 MHz to 2 GHz — a frequency range that includes the 1.2- and 1.5-GHz GPS frequencies.

Posted in: Briefs, Physical Sciences
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Nanodevices Based on Actin-Filament End-Tracking Motors

In a continuing research project, nanoscale actuators based on actin-filament end- tracking motors have been synthesized and characterized. It is envisioned that such actuators will eventually be utilized, variously, as molecular shuttles in biosensor devices or as nanoscale biomotors for effecting selection or separation of target microorganisms or molecules. In addition, this research is expected to enhance the fundamental understanding of molecular motors, both in vitro and in vivo and lead to modification of previously developed biomolecular machines and nanobiostructures to make them perform new functions. Some nanoscale actuators like those developed in this research may prove useful as components of micro- and nanofluidic systems. By contributing to understanding of how living cells convert chemical energy into mechanical work during actin-based and microtubule-based cell motility in cell crawling and cell mitosis, this research may lead to development of new therapeutic agents for combating invasive and metastatic cancers, gouty arthritis, Wiskott Aldrich syndrome, and those neurodegenerative disorders linked to loss of functional synapses.

Posted in: Briefs, Physical Sciences
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Tethered, Remotely Operated Miniature Submarine

A tethered, remotely operated, armed underwater vehicle has been conceived to satisfy a need for an uninhabited vehicle for Navy missions in which positive identification of targets is needed. Examples of such missions include those involving detection of swimmers and neutralization of mines. Unarmed versions of the vehicle might also be useful in civilian applications involving underwater inspections under hazardous conditions.

Posted in: Briefs, Mechanical Components
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Arcing and Vibration Tests of High-Power Patch Antennas

Electric-breakdown and vibration tests were performed on one-patch and two-patch versions of a prototype of a patch antenna designed to radiate a continuous- wave or pulsed signal in the S band (1.5 to 4 GHz) having a spectral width of 420 MHz and a peak power that could exceed 2 kW. This antenna is being developed for military use in neutralizing unattended improvised explosive devices. The patch antenna configuration was chosen for this development because it offers an efficient, less-bulky alternative to a conventional horn microwave antenna design.

Posted in: Briefs, Physical Sciences
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Antenna Electronically Steered Using MEMS Phase Shifters

An experimental phased-array microwave antenna assembly includes an array of eight patch antenna elements connected to Microelectromechanical System (MEMS) phase shifters, by means of which the directional radiation pattern of the antenna can be controlled electronically. The antenna and the MEMS-based phase shifters were designed for a nominal operating frequency of 17 GHz. In addition, some 35-GHz MEMS phase shifters were designed, built, and tested. This work is part of a continuing effort to develop relatively inexpensive electronically steerable antennas.

Posted in: Briefs, Physical Sciences
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