Photonic Recirculating Delay Line for Analog-to-Digital Conversion

Aconventional analog fiber-optic link can be augmented with a recirculating optical delay loop so as to realize an optically assisted analogto- digital converter (ADC) that provides improved performance in terms of both speed and resolution using one (slower) electronic ADC (see figure). The overall architecture readily integrates with any electronic ADC system. Moreover, the highspeed ADC performance is fundamentally limited by the performance of the fiber-optic link.

Posted in: Briefs, Photonics, Amplifiers, Fiber optics, Performance upgrades, Test procedures

Design and Development of a Package for a Diluted Waveguide Electro-Absorption Modulator

Externally coupled electroabsorption modulators (EAMs) are commonly used in order to transmit RF signals on optical fibers. Recently, an alternative device design with diluted waveguide structures was developed. Bench tests show benefits of lower propagation loss, higher power handling (100 mW), and higher normalized slope efficiency. Bench tests were performed in order to characterize the optical coupling of the EAM. The photo current maximum was offset from the optical power output maximum. The transmissions vs. bias voltage curves were measured, and an XY scanner was used to record the mode field of the light exiting from the EAM waveguide in each position. The Beam Propagation Method was used to simulate the mode field and the coupling efficiency. Based on the bench tests and simulation results, a design including mechanical, optical, and RF elements was developed.

Posted in: Briefs, Photonics, Design processes, Fiber optics, Waveguides

High-Resolution Anatomic and Elastographic Transrectal Ultrasound for Improved Diagnosis of Prostate Cancer

Prostate cancer screening generally uses the Pro state Spe cific Antigen (PSA) blood test, free-PSA testing, and Digital Rectal Exam ination (DRE). When the PSA is used, there exists a significant gray area in which cancers may be missed. Addition ally, DRE is practically limited to the detection of shallow (subcapsular) palpable abnormalities. Even systematic multi-core biopsy fails to detect clinically detectable cancers in up to 34% of men. Thus, there is compelling clinical interest in finding improved detection methods.

Posted in: Briefs, Medical, Diagnosis, Diseases, Physical examination, Acoustics, Test equipment and instrumentation

Characterizing Turbulent Wind Flow Near a Wind Barrier Using Sonic Anemometers

The Holloman High Speed Test Track (HHSTT) facility at Holloman Air Force Base (HAFB), NM, has a test section of 1.8 km that contains an artificial rain field generation capability over the track. The raindrops produced can be excessively deflected when the cross-track wind speed is greater than 1 m/s. To extend testing times to days when moderate wind conditions (1 to 5 m/s) are present, the HHSTT plans to construct a wind barrier for cross-track wind reduction. Before the construction of a complete wind barrier, an observational study was carried out to characterize the mean and turbulent wind fields using a small prototype section of the wind barrier.

Posted in: Briefs, Physical Sciences, Water, Test equipment and instrumentation, Test facilities, Turbulence

Frangible Polymer Circuit Acts as Tamper Sensor

Originally begun as an investigation to detect attempts to tap into an electrical cable, the emergence of modern encryption hardware rendered impractical attempts to protect communication media such as a cable.

Posted in: Briefs, Physical Sciences, Computer software / hardware, Cryptography, Cyber security, Integrated circuits, Polymers

Medical Information Network Decision Support System

In order to facilitate a more rapid and systematic transfer of new medical knowledge and capabilities into mainstream clinical practice, a new Medical Information Network Decision Support (MINDS) system has been proposed. This system is intended to be a platform for storing and fusing medical data across all levels (e.g. from low-level genomic and proteomic data to higher level clinical data) in a standardized way.

Posted in: Briefs, Software, Data exchange, Medical equipment and supplies, Data management

Multi-Agent Software for Airspace Control in the Combat Zone

AGENTFLY software is part of a computer-based system technology that will enhance airspace operation, providing ever-increasing support to personnel without freeing them from the ultimate responsibility. AGENTFLY features distributed coordination mechanisms based on collective decision-making and knowledge sharing, agent architecture, and specific agents responsible for data collection/ updating and planning/scheduling tasks, and the required visualization technology.

Posted in: Briefs, Software, Architecture, Computer software / hardware, Personnel, Air traffic control, Military aircraft

Multifunctional Properties of Structural Gel Electrolytes

Due to the demand for more advanced and lightweight systems, multifunctional composite structures that can function as electrochemical energy converters, while bearing mechanical load, are in development. This research involves a materials-based approach in which each component of the system serves to bear and/or efficiently transfer load. In this iteration, multifunctional structural gel electrolytes were prepared by the integration of conductive pathways using non-aqueous solvents into structural resin networks. Polyethylene glycol (200 MW) and propylene carbonate were used as the non-aqueous solvents, while vinyl ester and epoxy resin were used as structural resins. The monomer and solvents were incorporated together and polymerized to create conductive pathways in cross-linked networks. The impact of chemistry and weight fraction of both liquid and resin were investigated on the electrochemical-mechanical response of the resulting system.

Posted in: Briefs, Materials, Aircraft structures, Body structures, Composite materials, Electrolytes, Materials properties

Method for Detecting Planar Surfaces in Outdoor Urban Environments

The ability to detect and recognize buildings is important to a variety of vision applications operating in outdoor urban environments. These include landmark recognition, assisted and autonomous navigation, image-based rendering, and 3D scene modeling. The problem of detecting multiple planar surfaces from a single image has been solved with this technology.

Posted in: Briefs, Information Technology, Imaging, Product development

Dynamics of Epitaxy on Nano-Sized Semiconductor Surfaces

Semiconductor self-assembled quantum dots (QDs) have emerged as one of the simplest subjects for exploring and exploiting the physics and device applications of charge carriers and excitons in the three-dimensional confinement regime. Nanoscale-sized surfaces in the form of mesas or ridges on patterned substrates offer opportunities, not only for creating large densities of QDs with great homogeneity, but also for novel thin-film growth-control phenomena during the formation of QDs on the surfaces of Si stripe and mesa structures. Si mesa structures have been demonstrated to be an excellent template for studying homoepitaxy and heteroepitaxy phenomena.

Posted in: Briefs, Electronics & Computers, Nanotechnology, Semiconductors, Test equipment and instrumentation, Test procedures