Engineering Commons^™

Reduced Bandwidth For Remote Vehicle Operations, Timothy E. Noell, Fred W. Depiero

Electrical Engineering

Oak Ridge National Laboratory staff have developed a video compression system for low-bandwidth remote operations. The objective is to provide real-time video at data rates comparable to available tactical radio links, typically 16 to 64 thousand bits per second (kbps), while maintaining sufficient quality to achieve mission objectives. The system supports both continuous lossy transmission of black and white (gray scale) video for remote driving and progressive lossless transmission of black and white images for remote automatic target acquisition. The average data rate of the resulting bit stream is 64 kbps. This system has been demonstrated to provide video of …

The Naval Reserve Civil Engineer Corps Environmental Engineering Program, William A. Heine, Samuel A. Vigil

Civil and Environmental Engineering

The Navy is engaged in a national effort to bring its shore facilities into compliance with all applicable local, state, and federal environmental regulations. This work is being completed by civil service employees, consultants, and contractors under the supervision of Navy Civil Engineer Corps officers. To supplement these active duty and civilian resources, the Reserve Division of the Naval Facilities Engineering Command (RDNAVFAC) has identified Reserve officers with substantial environmental engineering skills who are being assigned to assist Navy shore activities all over the world in this essential task. The Naval Reserve Civil Engineer Corps (CEC) is composed of over …

Light-Emitting Diodes From Partially Conjugated Poly(P-Phenylene Vinylene), C. Zhang, David Braun, A. J. Heeger

Electrical Engineering

We report the effect of conversion conditions on the device characteristics of poly(p-phenylene vinylene) (PPV) light-emitting diodes. Both electroluminescence and photoluminescence intensities decrease with increasing degree of conversion. Partial conjugation enhances the electroluminescence intensity and gives an efficiency (with Ca as electron-injecting contact) as high as 0.75% photons per electron, about two orders of magnitude more efficient than from similar devices prepared from fully converted PPV. The results of constant current stress measurements suggest that the partially conjugated PPV diode is relatively stable at room temperature.

Measurement Of The Nonsteady Flow Field In The Opening Of A Resonating Cavity Excited By Grazing Flow, Hans R. Graf, William W. Durgin

Office of the Provost Scholarship

Flow past the opening of a cavity can excite acoustic resonance. The periodic velocity field in the region of the cavity opening has been measured for various flow conditions and the vorticity distribution has been computed from the measured data using numerical differentiation. The results indicate that the shear layer rolls up into discreet vortices, which travel across the cavity opening. Two resonances were found. The first is characterized by a single vortex being present and results in the greatest amplitude. The second is characterized by the presence of two vortices which excite a distinct but lesser amplitude resonance. As …

Analysis Of Laser Pulse Chirping In Mode-Locked Vertical-Cavity Surface-Emitting Lasers, Wenbin Jiang, Dennis J. Derickson, John E. Bowers

Electrical Engineering

Mode-locked vertical cavity lasers have a large cross-sectional area and consequently a large saturation energy and large peak powers. The authors analyze excess optical bandwidth generation in these lasers and find that self-phase modulation due to optical pumping and gain saturation is the dominant factor in inducing laser pulse chirping. The large magnitude of the chirp makes intracavity prism-pair compensation difficult. Adjustment of the cavity length has a major impact on the pulse chirping, as observed experimentally. Proper adjustment can result in a large linear frequency chirp which can be compensated using external pulse compression techniques

Evaluation Of Us Seismic Code Provisions For Asymmetric-Plan Systems, Rakesh K. Goel, Anil K. Chopra

Civil and Environmental Engineering

The effects of plan asymmetry on the earthquake response of code-designed, one-story systems are identified with the objective of evaluating how well these effects are represented by torsional provisions in US building codes. The earthquake-induced deformations and ductility demands on resisting elements of asymmetric-plan systems, are compared with their values if the system plan were symmetric. The presented results demonstrate that the design eccentricity in US building codes should be modified in order to achieve the desirable goal of similar ductility demands on asymmetric-plan and symmetric-plan systems. The design eccentricity should be defined differently depending on the design value of …

Numerical Prediction Of Transition Of The F-16 Wing At Supersonic Speeds, Russell M. Cummings

Aerospace Engineering

No abstract provided.

Semiconducting Polymer-Buckminsterfullerene Heterojunctions: Diodes, Photodiodes, And Photovoltaic Cells, N. S. Sariciftci, David Braun, C. Zhang, V. I. Srdanov, A. J. Heeger, G. Stucky, F. Wudl

Electrical Engineering

The characterization of rectifying heterojunctions (diodes) fabricated from a semiconducting polymer, a soluble derivative of poly(phenylene-vinylene), and buckminsterfullerene, C₆₀, are reported. Rectification ratios in the current versus voltage characteristics exceed 10⁴. When illuminated, the devices exhibit a large photoresponse as a result of photoinduced electron transfer across the heterojunction interface from the semiconducting polymer (donor) onto C₆₀ (acceptor). The photodiode and photovoltaic responses are characterized. Photoinduced electron transfer across the donor-accepted rectifying heterojunction offers potential for photodetector and for solar cell applications.

Low Gravity Environment On-Board Columbia During Sts-40, M. J.B. Rogers, C. R. Baugher, R. C. Blanchard, R. Delombard, William W. Durgin, D. H. Matthiesen, W. Neupert, P. Roussel

Office of the Provost Scholarship

The first NASA Spacelab Life Sciences mission (SLS-1) flew 5 June to 14 June 1991 on the orbiter Columbia (STS-40). The purpose of the mission was to investigate the human body's adaptation to the low gravity conditions of space flight and the body's readjustment after the mission to the 1 g environment of earth. In addition to the life sciences experiments manifested for the Spacelab module, a variety of experiments in other scientific disciplines flew in the Spacelab and in Get Away Special (GAS) Canisters on the GAS Bridge Assembly. Several principal investigators designed and flew specialized accelerometer systems to …

A Comparison Of Low-Gravity Measurements On-Board Columbia During Sts-40, M. J.B. Rogers, C. R. Baugher, R. C. Blanchard, R. Delombard, William W. Durgin, D. H. Matthiesen, W. Neupert, P. Roussel

Office of the Provost Scholarship

The first NASA Spacelab Life Sciences mission (SLS-1) flew 5 June to 14 June 1991 on the orbiter Columbia (STS-40). The purpose of the mission was to investigate the human body's adaptation to the low-gravity conditions of space flight and the body's readjustment after the mission to the 1 g environment of earth. In addition to the life sciences experiments manifested for the Spacelab module, a variety of experiments in other scientific disciplines flew in the Spacelab and in Get Away Special (GAS) Canisters on the GAS Bridge Assembly. Several principal investigators designed and flew specialized accelerometer systems to better …

Irrigation Methods For Drainage Reduction Subsurface Drip Vs. Furrow Irrigation, J.. D. Oster, R. B. Smith, C. Phene, A. Fulton, S. W. Styles, T. Fernandes

BioResource and Agricultural Engineering

No abstract provided.

Nanosecond Transient Electroluminescene From Polymer Light-Emitting Diodes, David Braun, D. Moses, C. Zhang, A. J. Heeger

Electrical Engineering

The transient electroluminescence from polymer light-emitting diodes is reported. When the devices are mounted on a microstrip transmission line, the temporal response is limited by the electrode geometry, with rise and fall times below 50 ns. With low duty-cycle pulses (0.5%) the electroluminescence intensity remains proportional to the current at values up to 10 A/cm², two orders of magnitude greater than possible under direct current operation. Since the spectral blue-shift observed at high current levels (with power dissipation above 1 W/cm²) indicates significant sample heating, still higher levels should be possible with proper thermal management.

Stabilization Of Passively Mode-Locked Semiconductor Laser Repetition Frequency, Roger Helkey, Dennis J. Derickson, Alan Mar, John Wasserbauer, Robert L. Thornton

Electrical Engineering

No abstract provided.

Nsf Sponsored Innovation In Engineering And Cornputer Science, Jacob Abel, Patricia Daniels, James G. Harris, Harry Hedges

Electrical Engineering

No abstract provided.

Model For The Infrastructure Of Engineering Education, James G. Harris, Karen Frair, Win Aung, Susan T. Hill

Electrical Engineering

There are many ways to describe and model physical systems. The infrastructure of engineering education in the United States is an example of such a system, and it is the intent of this report to describe and model this infratructure. The means for doing this starts with the graduation statistics for the year 1989 given by the Computer Aided Science Policy Analysis & Research Database System (CASPAR) developed for the National Science Foundation by Quantum Research Corporation [1], and uses a simple categorization for the institutions that contribute to those statistics. This categorization sorts the post -secondary institutions in the …

Flow Excited Acoustic Resonance In A Deep Cavity: An Analytical Model, William W. Durgin, Hans R. Graf

Office of the Provost Scholarship

Flow past the opening of a deep cavity can excite and sustain longitudinal acoustic modes resulting in large pressure fluctuations and loud tone generation. An analytic model of the interaction of the free stream with the acoustic flow field using concentrated vortices in the shear layer is proposed. The model includes a computation of the power transferred by the traveling vortices to the acoustic oscillation in the cavity. Experimentally measured values for the vortex convection velocity and phase are used to enable calculation of the ensuing oscillation amplititude and frequency ratio. The radiated acoustic power is calculated using the model …

Spaceflight Payload Design, Flight Experience G-408, William W. Durgin, Fred J. Looft, Albert Sacco, Jr., Robert Thompson, Anthony G. Dixon, Dino Roberti, Robert Labonte, Larry Moschini

Office of the Provost Scholarship

Worcester Polytechnic Institute's first payload of spaceflight experiments flew aboard Columbia, STS-40, during June of 1991 and culminated eight years of work by students and faculty. The Get Away Special (GAS) payload was installed on the GAS bridge assembly at the aft end of the cargo bay behind the Spacelab Life Sciences (SLS-l) laboratory. The experiments were turned on by astronaut signal after reaching orbit and then functioned for 72 hours. Environmental and experimental measurements were recorded on three cassette tapes which, together with zeolite crystals grown on orbit, formed the basis of subsequent analyses.

The experiments were developed over …

Short Pulse Generation Using Multisegment Mode-Locked Semiconductor Lasers, Dennis J. Derickson, R. J. Helkey, A. Mar, Judy R. Karin, J. G. Wasserbauer, J. E. Bowers

Electrical Engineering

No abstract provided.

Artificial Neural Networks For Robotics Coordinate Transformation, Stephen Aylor, Luis Rabelo, Sema E. Alptekin

Industrial and Manufacturing Engineering

Artificial neural networks with such characteristics as learning, graceful degradation, and speed inherent to parallel distributed architectures might provide a flexible and cost solution to the real time control of robotics systems. In this investigation artificial neural networks are presented for the coordinate transformation mapping of a two-axis robot modeled with Fischertechnik physical modeling components. The results indicate that artificial neural systems could be utilized for practical situations and that extended research in these neural structures could provide adaptive architectures for dynamic robotics control.

Waste-Surface Mapping Of The Fernald K-65 Silos Using A Structured Light Measurement System, B. L. Burks, Fred W. Depiero, M. A. Dinkins, J. C. Rowe, C. B. Selleck, D. L. Jacoboski

Electrical Engineering

During FY 1991, a remotely operated surface-mapping measurement system was developed by the Robotics & Process Systems Division at Oak Ridge National Laboratory for use in the K-65 waste-storage silos at Fernald, Ohio. The mapping system used three infrared line-generating laser diodes as illumination sources and three high-resolution, low-lux, calibrated, black-and-white, chargecoupled- device video cameras as receivers. These components were combined to form structured light source range and direction sensors with six different possible emitter-receiver pairs. A technology demonstration and predeployment tests were performed at Fernald during July and August 1991, using the empty Silo 4 into which was placed …

Morphology, Deformation, And Defect Structures Of Ticr2 In Ti-Cr Alloys, Katherine C. Chen, Samuel M. Allen, James D. Livingston

Materials Engineering

The morphologies and defect structures of TiCr₂ in several Ti-Cr alloys have been examined by optical metallography, x-ray diffraction, and transmission electron microscopy (TEM), in order to explore the room-temperature deformability of the Laves phase TiCr₂. The morphology of the Laves phase was found to be dependent upon alloy composition and annealing temperature. Samples deformed by compression have also been studied using TEM. Comparisons of microstructures before and after deformation suggest an increase in twin, stacking faul4 and dislocation density within the Laves phase, indicating some but not extensive room-temperature deformability.

Repetition Frequency Stabilisation Of Passively Mode-Locked Semiconductor Lasers, R. J. Helkey, Dennis J. Derickson, A. Mar, J. G. Wasserbauer, J. E. Bowers, R. L. Thornton

Electrical Engineering

The repetition frequency of an external cavity mode-locked GaAs semiconductor diode laser has been stabilized by voltage controlled electrical feedback. The phase noise has been reduced by 40dB at 1 kHz offset from the carrier and timing jitter reduced from more than 30ps to 4ps. This technique can be used to stabilize millimetre-wave mode-locked lasers.

Mode-Locking Of High-Power Resonant-Optical-Waveguide Diode Laser Arrays, Alan Mar, Dennis J. Derickson, Roger Helkey, John Bowers, Dan Botez

Electrical Engineering

We report the first mode-locked operation of a resonant optical waveguide (ROW semiconductor laser array. Pulsewidths as short as 23 ps and peak powers of over 1W are generated in a single-lobed beam.

Automatic Recognition Of Tool Wear On A Face Mill Using A Mechanistic Modeling Approach, Daniel Waldorf, Shiv G. Kapoor, Richard E. Devor

Industrial and Manufacturing Engineering

A strategy is developed for identifying cutting tool wear on a face mill by automatically recognizing wear patterns in the cutting force signal. The strategy uses a mechanistic model development to predict forces on a lathe under conditions of wear and extends that model to account for the multiple inserts of a face mill. The extended wear model is then verified through experimentation over the life of the inserts. The predicted force signals are employed to train linear discriminant functions to identify the wear state of the process in a manner suitable for on-line application.

Methanotrophic Bacteria For Nutrient Removal From Wastewater: Attached Film System, William J. Jewell, Yarrow M. Nelson, Mark S. Wilson

Civil and Environmental Engineering

It was hypothesized that nutrient removal from wastewater could be achieved by using methane oxidizing bacteria (methanotrophs). Because methane is inexpensive. it can be used as an energy source to encourage bacterial growth to assimilate nitrogen and phosphorus and other trace elements. This initial feasibility study used synthetic nutrient mixtures and secondary sewage effluent as feed to a laboratory-scale methanotrophic attached-film expanded bed (MAFEB) reactor operated at 35°C and 20°C. The MAFEB system operated successfully at low nutrient concentrations under a variety of nutrient-limited conditions. Using a synthetic nutrient mixture with a nitrogen:phosphorus feed ratio (w/w) …

On The Creep Deformation Of A Cast Near Gamma Tial Alloy Ti-48al-1nb, R. W. Hayes, B. London

Materials Engineering

The steady-state creep deformation behavior of a cast two phase gamma TiAl alloy having the composition Ti---48Al---1Nb (at.%) has been studied. Tension creep tests using the stress increment technique (θθ2θ3) were conducted over the temperature range of 704–850°C at constant initial applied stress level of 103.4–241.3 MPa. The activation energy for creep over the temperature and stress regime of this study varied 317.5 kJ/mol (137.8 MPa) up to 341.0 kJ/mol (206.8 MPa) with an average value of 326.4 kJ/mol. This is well within the range of values previously measured for gamma TiAl alloys where creep controlled by volume diffusion has …

Remote Driving With Reduced Bandwidth Communication, Fred W. Depiero, Timothy E. Noell, Timothy F. Gee

Electrical Engineering

Oak Ridge National Laboratory has developed a real-time video transmission system for low-bandwidth remote operations. The system supports both continuous transmission of video for remote driving and progressive transmission of still images. Inherent in the system design is a spatiotemporal limitation to the effects of channel errors. The average data rate of the system is 64,000 bits/s, a compression of approximately 1000:1 for the black and white National Television Standard Code video. The image quality of the transmissions is maintained at a level that supports teleoperation of a high-mobility multipurpose wheeled vehicle at speeds up to 15 mph on a …

Integrated Optical Transmitters And Receivers Using Multi-Segment Laser Processes, J. G. Wasserbauer, Dennis J. Derickson, K. Giboney, R. J. Helkey, J. R. Karin, A. Mar, J. E. Bowers

Electrical Engineering

No abstract provided.

Electroluminescence And Electrical Transport In Poly(3-Octylthiophene) Diodes, David Braun, G. Gustafsson, D. Mcbranch, A. J. Heeger

Electrical Engineering

We report visible light emission from diodes made from poly(3-octylthiophene). Use of a soluble derivative of polythiophene allows fabrication of the light emitting diodes by casting the polymer film from solution with no subsequent processing or heat treatment required. The devices emit dim red-orange light with relatively low external quantum efficiencies, below 2.5×10⁻⁵ photons per electron at room temperature. Electrical characterization reveals diode behavior with rectification ratios greater than 10². The temperature dependence indicates that tunneling phenomena dominate the charge injection.

Application Of An Itô-Based Approximation Method To Random Vibration Of A Pinching Hysteretic System, Mohammad N. Noori, Mark D. Padua, Hamid Davoodi

Office of the Dean (CENG) Scholarship

In this paper, an extension of the Cumulant-Neglect closure scheme is utilized for the random vibration analysis of a single degree of freedom system with a general pinching hysteresis restoring force. The hysteresis element used in the system model can simulate commonly observed forms of stiffness, strength and pinching degradations. The second order statistics of the system response to a stationary Gaussian white noise input are derived using an Itô-based approximation technique. The validity of these response statistics are then verified by comparing them to Monte Carlo simulation results. The numerical studies performed for different combinations of degradation parameters and …