Two laboratory methods for the calibration of GPS speed meters

NASA Astrophysics Data System (ADS)

Bai, Yin; Sun, Qiao; Du, Lei; Yu, Mei; Bai, Jie

2015-01-01

The set-ups of two calibration systems are presented to investigate calibration methods of GPS speed meters. The GPS speed meter calibrated is a special type of high accuracy speed meter for vehicles which uses Doppler demodulation of GPS signals to calculate the measured speed of a moving target. Three experiments are performed: including simulated calibration, field-test signal replay calibration, and in-field test comparison with an optical speed meter. The experiments are conducted at specific speeds in the range of 40-180 km h-1 with the same GPS speed meter as the device under calibration. The evaluation of measurement results validates both methods for calibrating GPS speed meters. The relative deviations between the measurement results of the GPS-based high accuracy speed meter and those of the optical speed meter are analyzed, and the equivalent uncertainty of the comparison is evaluated. The comparison results justify the utilization of GPS speed meters as reference equipment if no fewer than seven satellites are available. This study contributes to the widespread use of GPS-based high accuracy speed meters as legal reference equipment in traffic speed metrology.

Principle and Performance of Gas Self-inducing Reactors and Applications to Biotechnology.

PubMed

Ye, Qin; Li, Zhimin; Wu, Hui

2016-01-01

Gas-liquid contacting is an important unit operation in chemical and biochemical processes, but the gas utilization efficiency is low in conventional gas-liquid contactors especially for sparingly soluble gases. The gas self-inducing impeller is able to recycle gas in the headspace of a reactor to the liquid without utilization of additional equipment such as a gas compressor, and thus, the gas utilization efficiency is significantly enhanced. Gas induction is caused by the low pressure or deep vortex at a sufficiently high impeller speed, and the speed at which gas induction starts is termed the critical speed. The critical impeller speed, gas-induction flow rate, power consumption, and gas-liquid mass transfer are determined by the impeller design and operation conditions. When the reactor is operated in a dead-end mode, all the introduced gas can be completely used, and this feature is especially favorable to flammable and/or toxic gases. In this article, the principles, designs, characteristics of self-inducing reactors, and applications to biotechnology are described.

High Speed Solid State Circuit Breaker

NASA Technical Reports Server (NTRS)

Podlesak, Thomas F.

1993-01-01

The U.S. Army Research Laboratory, Fort Monmouth, NJ, has developed and is installing two 3.3 MW high speed solid state circuit breakers at the Army's Pulse Power Center. These circuit breakers will interrupt 4160V three phase power mains in no more than 300 microseconds, two orders of magnitude faster than conventional mechanical contact type circuit breakers. These circuit breakers utilize Gate Turnoff Thyristors (GTO's) and are currently utility type devices using air cooling in an air conditioned enclosure. Future refinements include liquid cooling, either water or two phase organic coolant, and more advanced semiconductors. Each of these refinements promises a more compact, more reliable unit.

Functional form for plasma velocity in a rapidly rotating tokamak discharge

DOE PAGES

Burrell, Keith H.; Chrystal, C. olin

2014-07-25

A recently developed technique using charge exchange spectroscopy determines the ion poloidal rotation in tokamak plasmas from the poloidal variation in the toroidal angular rotation speed. The basis for this technique is the functional form for the plasma velocity calculated from the equilibrium equations. The initial development of this technique utilized the functional form determined for conditions where the ion toroidal rotation speed is much smaller than the ion thermal speed. There are cases, however, where the toroidal rotation can be comparable to the ion thermal speed, especially for high atomic number impurities. Furthermore, the present paper extends the previousmore » analysis to this high rotation speed case and demonstrates how to extract the poloidal rotation speed from measurements of the toroidal angular rotation speed at two points on a flux surface.« less

23 CFR 645.205 - Policy.

Code of Federal Regulations, 2011 CFR

2011-04-01

... corridors, it is essential in such situations that these public service facilities be compatibly designed... joint highway and utility development of transportation corridors is important along high speed and high...

Advanced turboprop noise prediction based on recent theoretical results

NASA Technical Reports Server (NTRS)

Farassat, F.; Padula, S. L.; Dunn, M. H.

1987-01-01

The development of a high speed propeller noise prediction code at Langley Research Center is described. The code utilizes two recent acoustic formulations in the time domain for subsonic and supersonic sources. The structure and capabilities of the code are discussed. Grid size study for accuracy and speed of execution on a computer is also presented. The code is tested against an earlier Langley code. Considerable increase in accuracy and speed of execution are observed. Some examples of noise prediction of a high speed propeller for which acoustic test data are available are given. A brisk derivation of formulations used is given in an appendix.

Overview of High Speed Close-Up Imaging in an Icing Environment

NASA Technical Reports Server (NTRS)

Miller, Dean R.; Lynch, Christopher J.; Tate, Peter A.

2004-01-01

The Icing Branch and Imaging Technology Center at NASA Glenn Research Center have recently been involved in several projects where high speed close-up imaging was used to investigate water droplet impact/splash, and also ice particle impact/bounce in an icing wind tunnel. The combination of close-up and high speed imaging capabilities were required because the particles being studied were relatively small (d < 1 mm in diameter), and the impact process occurred in a very short time period (t(sub impact) << 1 sec). High speed close-up imaging was utilized to study the dynamics of droplet impact and splash in simulated Supercooled Large Droplet (SLD) icing conditions. The objective of this test was to evaluate the capability of a ultra high speed camera system to acquire quantitative information about the impact process (e.g., droplet size, velocity). Imaging data were obtained in an icing wind tunnel for spray cloud MVD > 50 m. High speed close-up imaging was also utilized to characterize the impact of ice particles on an airfoil with a thermally protected leading edge. The objective of this investigation was to determine whether ice particles tend to "stick" or "bounce" after impact. Imaging data were obtained for cases where the airfoil surface was heated and unheated. Based on the results from this test, follow on tests were conducted to investigate ice particle impact on the sensing elements of water content measurement devices. This paper will describe the use of the imaging systems to support these experimental investigations, present some representative results, and summarize what was learned about the use of these systems in an icing environment.

Excessive centrifugal fields damage high density lipoprotein[S

PubMed Central

Munroe, William H.; Phillips, Martin L.; Schumaker, Verne N.

2015-01-01

HDL is typically isolated ultracentrifugally at 40,000 rpm or greater, however, such high centrifugal forces are responsible for altering the recovered HDL particle. We demonstrate that this damage to HDL begins at approximately 30,000 rpm and the magnitude of loss increases in a rotor speed-dependent manner. The HDL is affected by elevated ultracentrifugal fields resulting in a lower particle density due to the shedding of associated proteins. To circumvent the alteration of the recovered HDL, we utilize a KBr-containing density gradient and a lowered rotor speed of 15,000 rpm to separate the lipoproteins using a single 96 h centrifugation step. This recovers the HDL at two density ranges; the bulk of the material has a density of about 1.115 g/ml, while lessor amounts of material are recovered at >1.2 g/ml. Thus, demonstrating the isolation of intact HDL is possible utilizing lower centrifuge rotor speeds. PMID:25910941

High Speed and High Spatial Density Parameter Measurement Using Fiber Optic Sensing Technology

NASA Technical Reports Server (NTRS)

Richards, William Lance (Inventor); Piazza, Anthony (Inventor); Parker, Allen R. Jr. (Inventor); Hamory, Philip J (Inventor); Chan, Hon Man (Inventor)

2017-01-01

The present invention is an improved fiber optic sensing system (FOSS) having the ability to provide both high spatial resolution and high frequency strain measurements. The inventive hybrid FOSS fiber combines sensors from high acquisition speed and low spatial resolution Wavelength-Division Multiplexing (WDM) systems and from low acquisition speed and high spatial resolution Optical Frequency Domain Reflection (OFDR) systems. Two unique light sources utilizing different wavelengths are coupled with the hybrid FOSS fiber to generate reflected data from both the WDM sensors and OFDR sensors operating on a single fiber optic cable without incurring interference from one another. The two data sets are then de-multiplexed for analysis, optionally with conventionally-available WDM and OFDR system analyzers.

A frequency and sensitivity tunable microresonator array for high-speed quantum processor readout

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whittaker, J. D., E-mail: jwhittaker@dwavesys.com; Swenson, L. J.; Volkmann, M. H.

Superconducting microresonators have been successfully utilized as detection elements for a wide variety of applications. With multiplexing factors exceeding 1000 detectors per transmission line, they are the most scalable low-temperature detector technology demonstrated to date. For high-throughput applications, fewer detectors can be coupled to a single wire but utilize a larger per-detector bandwidth. For all existing designs, fluctuations in fabrication tolerances result in a non-uniform shift in resonance frequency and sensitivity, which ultimately limits the efficiency of bandwidth utilization. Here, we present the design, implementation, and initial characterization of a superconducting microresonator readout integrating two tunable inductances per detector. Wemore » demonstrate that these tuning elements provide independent control of both the detector frequency and sensitivity, allowing us to maximize the transmission line bandwidth utilization. Finally, we discuss the integration of these detectors in a multilayer fabrication stack for high-speed readout of the D-Wave quantum processor, highlighting the use of control and routing circuitry composed of single-flux-quantum loops to minimize the number of control wires at the lowest temperature stage.« less

High-speed adaptive contact-mode atomic force microscopy imaging with near-minimum-force

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Juan; Zou, Qingze, E-mail: qzzou@rci.rutgers.edu

In this paper, an adaptive contact-mode imaging approach is proposed to replace the traditional contact-mode imaging by addressing the major concerns in both the speed and the force exerted to the sample. The speed of the traditional contact-mode imaging is largely limited by the need to maintain precision tracking of the sample topography over the entire imaged sample surface, while large image distortion and excessive probe-sample interaction force occur during high-speed imaging. In this work, first, the image distortion caused by the topography tracking error is accounted for in the topography quantification. Second, the quantified sample topography is utilized inmore » a gradient-based optimization method to adjust the cantilever deflection set-point for each scanline closely around the minimal level needed for maintaining stable probe-sample contact, and a data-driven iterative feedforward control that utilizes a prediction of the next-line topography is integrated to the topography feeedback loop to enhance the sample topography tracking. The proposed approach is demonstrated and evaluated through imaging a calibration sample of square pitches at both high speeds (e.g., scan rate of 75 Hz and 130 Hz) and large sizes (e.g., scan size of 30 μm and 80 μm). The experimental results show that compared to the traditional constant-force contact-mode imaging, the imaging speed can be increased by over 30 folds (with the scanning speed at 13 mm/s), and the probe-sample interaction force can be reduced by more than 15% while maintaining the same image quality.« less

High-speed adaptive contact-mode atomic force microscopy imaging with near-minimum-force.

PubMed

Ren, Juan; Zou, Qingze

2014-07-01

In this paper, an adaptive contact-mode imaging approach is proposed to replace the traditional contact-mode imaging by addressing the major concerns in both the speed and the force exerted to the sample. The speed of the traditional contact-mode imaging is largely limited by the need to maintain precision tracking of the sample topography over the entire imaged sample surface, while large image distortion and excessive probe-sample interaction force occur during high-speed imaging. In this work, first, the image distortion caused by the topography tracking error is accounted for in the topography quantification. Second, the quantified sample topography is utilized in a gradient-based optimization method to adjust the cantilever deflection set-point for each scanline closely around the minimal level needed for maintaining stable probe-sample contact, and a data-driven iterative feedforward control that utilizes a prediction of the next-line topography is integrated to the topography feeedback loop to enhance the sample topography tracking. The proposed approach is demonstrated and evaluated through imaging a calibration sample of square pitches at both high speeds (e.g., scan rate of 75 Hz and 130 Hz) and large sizes (e.g., scan size of 30 μm and 80 μm). The experimental results show that compared to the traditional constant-force contact-mode imaging, the imaging speed can be increased by over 30 folds (with the scanning speed at 13 mm/s), and the probe-sample interaction force can be reduced by more than 15% while maintaining the same image quality.

Effect of twist on transverse impact response of ballistic fiber yarns

DOE PAGES

Song, Bo; Lu, Wei -Yang

2015-06-15

A Hopkinson bar was employed to conduct transverse impact testing of twisted Kevlar KM2 fiber yarns at the same impact speed. The speed of Euler transverse wave generated by the impact was measured utilizing a high speed digital camera. The study included fiber yarns twisted by different amounts. The Euler transverse wave speed was observed to increase with increasing amount of twist of the fiber yarn, within the range of this investigation. As a result, the higher transverse wave speeds in the more twisted fiber yarns indicate better ballistic performance in soft body armors for personal protection.

Penetration into Granular Earth Materials (Topic H): A Multi-scale Physics-Based Approach Towards Developing a Greater Understanding of Dynamically Loaded Heterogeneous Systems

DTIC Science & Technology

2016-08-01

7 2.1. DYNAMIC DART GUN EXPERIMENTS...penetration, and cavity formation associated with high-speed projectile penetration of sand. A new half-inch gun was constructed for this project. A...inch gun with them. Data was collected utilizing NSWC’s Cordin 550, 64 frame, high-speed camera. In addition, several student participated in the

Volterra equalization of complex modulation utilizing frequency chirp in directly modulated lasers

NASA Astrophysics Data System (ADS)

Hu, Shaohua; Yi, Xingwen; Zhang, Jing; Song, Yang; Zhu, Mingyue; Qiu, Kun

2018-02-01

We apply Volterra-based equalization for complex modulated optical signals utilizing the frequency chirp in DMLs. We experimentally demonstrate that the higher order Volterra filter is necessary in the higher speed transmissions. For further study, we isolate the adiabatic chirp by injection locking and realize the optical PM transmission. We make a comparison among IM, FM and PM with Volterra equalization, finding that PM and FM are more power insensitive and suitable for high speed, power limited fiber transmission. The performance can be further improved by exploiting the diversity gain.

Long-range high-speed visible light communication system over 100-m outdoor transmission utilizing receiver diversity technology

NASA Astrophysics Data System (ADS)

Wang, Yiguang; Huang, Xingxing; Shi, Jianyang; Wang, Yuan-quan; Chi, Nan

2016-05-01

Visible light communication (VLC) has no doubt become a promising candidate for future wireless communications due to the increasing trends in the usage of light-emitting diodes (LEDs). In addition to indoor high-speed wireless access and positioning applications, VLC usage in outdoor scenarios, such as vehicle networks and intelligent transportation systems, are also attracting significant interest. However, the complex outdoor environment and ambient noise are the key challenges for long-range high-speed VLC outdoor applications. To improve system performance and transmission distance, we propose to use receiver diversity technology in an outdoor VLC system. Maximal ratio combining-based receiver diversity technology is utilized in two receivers to achieve the maximal signal-to-noise ratio. A 400-Mb/s VLC transmission using a phosphor-based white LED and a 1-Gb/s wavelength division multiplexing VLC transmission using a red-green-blue LED are both successfully achieved over a 100-m outdoor distance with the bit error rate below the 7% forward error correction limit of 3.8×10-3. To the best of our knowledge, this is the highest data rate at 100-m outdoor VLC transmission ever achieved. The experimental results clearly prove the benefit and feasibility of receiver diversity technology for long-range high-speed outdoor VLC systems.

A high sensitivity 20Mfps CMOS image sensor with readout speed of 1Tpixel/sec for visualization of ultra-high speed phenomena

NASA Astrophysics Data System (ADS)

Kuroda, R.; Sugawa, S.

2017-02-01

Ultra-high speed (UHS) CMOS image sensors with on-chop analog memories placed on the periphery of pixel array for the visualization of UHS phenomena are overviewed in this paper. The developed UHS CMOS image sensors consist of 400H×256V pixels and 128 memories/pixel, and the readout speed of 1Tpixel/sec is obtained, leading to 10 Mfps full resolution video capturing with consecutive 128 frames, and 20 Mfps half resolution video capturing with consecutive 256 frames. The first development model has been employed in the high speed video camera and put in practical use in 2012. By the development of dedicated process technologies, photosensitivity improvement and power consumption reduction were simultaneously achieved, and the performance improved version has been utilized in the commercialized high-speed video camera since 2015 that offers 10 Mfps with ISO16,000 photosensitivity. Due to the improved photosensitivity, clear images can be captured and analyzed even under low light condition, such as under a microscope as well as capturing of UHS light emission phenomena.

Advanced turboprop noise prediction: Development of a code at NASA Langley based on recent theoretical results

NASA Technical Reports Server (NTRS)

Farassat, F.; Dunn, M. H.; Padula, S. L.

1986-01-01

The development of a high speed propeller noise prediction code at Langley Research Center is described. The code utilizes two recent acoustic formulations in the time domain for subsonic and supersonic sources. The structure and capabilities of the code are discussed. Grid size study for accuracy and speed of execution on a computer is also presented. The code is tested against an earlier Langley code. Considerable increase in accuracy and speed of execution are observed. Some examples of noise prediction of a high speed propeller for which acoustic test data are available are given. A brisk derivation of formulations used is given in an appendix.

High-Speed Lateral Flow Strategy for a Fast Biosensing with an Improved Selectivity and Binding Affinity.

PubMed

Cho, Dong Guk; Yoo, Haneul; Lee, Haein; Choi, Yeol Kyo; Lee, Minju; Ahn, Dong June; Hong, Seunghun

2018-05-10

We report a high-speed lateral flow strategy for a fast biosensing with an improved selectivity and binding affinity even under harsh conditions. In this strategy, biosensors were fixed at a location away from the center of a round shape disk, and the disk was rotated to create the lateral flow of a target solution on the biosensors during the sensing measurements. Experimental results using the strategy showed high reaction speeds, high binding affinity, and low nonspecific adsorptions of target molecules to biosensors. Furthermore, binding affinity between target molecules and sensing molecules was enhanced even in harsh conditions such as low pH and low ionic strength conditions. These results show that the strategy can improve the performance of conventional biosensors by generating high-speed lateral flows on a biosensor surface. Therefore, our strategy can be utilized as a simple but powerful tool for versatile bio and medical applications.

The Elite: A high speed, low-cost general aviation aircraft for Aeroworld

NASA Technical Reports Server (NTRS)

Rueter, Amy; Fay, Jonathan; Staudmeister, Douglas; Avis, Daniel; Le, Tuan; Stem, Steven

1994-01-01

The Elite is a six passenger, general aviation aircraft targeted at the upper middle class private pilot. The Elite is a low wing, conventional monoplane utilizing rudder, ailerons, and a stabilator. The Elite will create a new class of aircraft in Aeroworld. This class of aircraft will demonstrate a substantial improvement in cruise speed over the current existing commercial fleet of aircraft in Aeroworld. This new class will be capable of servicing all existing airstrips in Aeroworld, including rough and short airways. The drivers of this design were aesthetics, a high cruise speed, and take-off distance.

Perils of using speed zone data to assess real-world compliance to speed limits.

PubMed

Chevalier, Anna; Clarke, Elizabeth; Chevalier, Aran John; Brown, Julie; Coxon, Kristy; Ivers, Rebecca; Keay, Lisa

2017-11-17

Real-world driving studies, including those involving speeding alert devices and autonomous vehicles, can gauge an individual vehicle's speeding behavior by comparing measured speed with mapped speed zone data. However, there are complexities with developing and maintaining a database of mapped speed zones over a large geographic area that may lead to inaccuracies within the data set. When this approach is applied to large-scale real-world driving data or speeding alert device data to determine speeding behavior, these inaccuracies may result in invalid identification of speeding. We investigated speeding events based on service provider speed zone data. We compared service provider speed zone data (Speed Alert by Smart Car Technologies Pty Ltd., Ultimo, NSW, Australia) against a second set of speed zone data (Google Maps Application Programming Interface [API] mapped speed zones). We found a systematic error in the zones where speed limits of 50-60 km/h, typical of local roads, were allocated to high-speed motorways, which produced false speed limits in the speed zone database. The result was detection of false-positive high-range speeding. Through comparison of the service provider speed zone data against a second set of speed zone data, we were able to identify and eliminate data most affected by this systematic error, thereby establishing a data set of speeding events with a high level of sensitivity (a true positive rate of 92% or 6,412/6,960). Mapped speed zones can be a source of error in real-world driving when examining vehicle speed. We explored the types of inaccuracies found within speed zone data and recommend that a second set of speed zone data be utilized when investigating speeding behavior or developing mapped speed zone data to minimize inaccuracy in estimates of speeding.

Underwater Acoustic Tracer System

DTIC Science & Technology

2009-03-13

for controlling and utilizing supercavitating projectile dynamics to produce a distinctive radiated noise signal. (2) Description of the Prior Art...metallic objects which travel relatively closely to a magnetic pickup. For larger, high speed, underwater projectiles, supercavitating underwater vehicles...have been proposed for use. The conditions for supercavitation are known in the art. Supercavitation allows for higher speeds to be sustainable

Experimental investigation of a variable speed constant frequency electric generating system from a utility perspective

NASA Technical Reports Server (NTRS)

Herrera, J. I.; Reddoch, T. W.; Lawler, J. S.

1985-01-01

As efforts are accelerated to improve the overall capability and performance of wind electric systems, increased attention to variable speed configurations has developed. A number of potentially viable configurations have emerged. Various attributes of variable speed systems need to be carefully tested to evaluate their performance from the utility points of view. With this purpose, the NASA experimental variable speed constant frequency (VSCF) system has been tested. In order to determine the usefulness of these systems in utility applications, tests are required to resolve issues fundamental to electric utility systems. Legitimate questions exist regarding how variable speed generators will influence the performance of electric utility systems; therefore, tests from a utility perspective, have been performed on the VSCF system and an induction generator at an operating power level of 30 kW on a system rated at 200 kVA and 0.8 power factor.

Embedded system of image storage based on fiber channel

NASA Astrophysics Data System (ADS)

Chen, Xiaodong; Su, Wanxin; Xing, Zhongbao; Wang, Hualong

2008-03-01

In domains of aerospace, aviation, aiming, and optic measure etc., the embedded system of imaging, processing and recording is absolutely necessary, which has small volume, high processing speed and high resolution. But the embedded storage technology becomes system bottleneck because of developing slowly. It is used to use RAID to promote storage speed, but it is unsuitable for the embedded system because of its big volume. Fiber channel (FC) technology offers a new method to develop the high-speed, portable storage system. In order to make storage subsystem meet the needs of high storage rate, make use of powerful Virtex-4 FPGA and high speed fiber channel, advance a project of embedded system of digital image storage based on Xilinx Fiber Channel Arbitrated Loop LogiCORE. This project utilizes Virtex- 4 RocketIO MGT transceivers to transmit the data serially, and connects many Fiber Channel hard drivers by using of Arbitrated Loop optionally. It can achieve 400MBps storage rate, breaks through the bottleneck of PCI interface, and has excellences of high-speed, real-time, portable and massive capacity.

High-speed polarized light microscopy for in situ, dynamic measurement of birefringence properties

NASA Astrophysics Data System (ADS)

Wu, Xianyu; Pankow, Mark; Shadow Huang, Hsiao-Ying; Peters, Kara

2018-01-01

A high-speed, quantitative polarized light microscopy (QPLM) instrument has been developed to monitor the optical slow axis spatial realignment during controlled medium to high strain rate experiments at acquisition rates up to 10 kHz. This high-speed QPLM instrument is implemented within a modified drop tower and demonstrated using polycarbonate specimens. By utilizing a rotating quarter wave plate and a high-speed camera, the minimum acquisition time to generate an alignment map of a birefringent specimen is 6.1 ms. A sequential analysis method allows the QPLM instrument to generate QPLM data at the high-speed camera imaging frequency 10 kHz. The obtained QPLM data is processed using a vector correlation technique to detect anomalous optical axis realignment and retardation changes throughout the loading event. The detected anomalous optical axis realignment is shown to be associated with crack initiation, propagation, and specimen failure in a dynamically loaded polycarbonate specimen. The work provides a foundation for detecting damage in biological tissues through local collagen fiber realignment and fracture during dynamic loading.

High Resolution, High-Speed Photography, an Increasingly Prominent Diagnostic in Ballistic Research Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, L.; Muelder, S.

1999-10-22

High resolution, high-speed photography is becoming a prominent diagnostic in ballistic experimentation. The development of high speed cameras utilizing electro-optics and the use of lasers for illumination now provide the capability to routinely obtain high quality photographic records of ballistic style experiments. The purpose of this presentation is to review in a visual manner the progress of this technology and how it has impacted ballistic experimentation. Within the framework of development at LLNL, we look at the recent history of large format high-speed photography, and present a number of photographic records that represent the state of the art at themore » time they were made. These records are primarily from experiments involving shaped charges. We also present some examples of current photographic technology, developed within the ballistic community, that has application to hydro diagnostic experimentation at large. This paper is designed primarily as an oral-visual presentation. This written portion is to provide general background, a few examples, and a bibliography.« less

The dynamic development of the muzzle imprint by contact gunshot: high-speed documentation utilizing the "skin-skull-brain model".

PubMed

Thali, M J; Kneubuehl, B P; Dirnhofer, R; Zollinger, U

2002-07-17

Many contact gunshots produce a muzzle imprint in the skin of the victim. Different mechanisms have been discussed in literature as being responsible for the creation of the muzzle imprint. Experimenting upon the synthetic non biological skin-skull-brain model, our goal was to document and study the creation of the muzzle imprint with the aid of high-speed photography. In our experiments, we could document with our high-speed photography (at exposure rates in the range of nanoseconds) the bulging, the pressing against the muzzle, and the splitting of the artificial skin. Furthermore, it was possible to photographically record the back pattern of synthetic tissue particles. And, the soot and gunpowder cavity could be reproduced experimentally. In conclusion the experiments completed with the skin-skull-brain model, using high-speed photography for documentation, show the promising possibilities of experimental ballistics with body models.

Powertrain system for a hybrid electric vehicle

DOEpatents

Reed, Jr., Richard G.; Boberg, Evan S.; Lawrie, Robert E.; Castaing, Francois J.

1999-08-31

A hybrid electric powertrain system is provided including an electric motor/generator drivingly engaged with the drive shaft of a transmission. The electric is utilized for synchronizing the rotation of the drive shaft with the driven shaft during gear shift operations. In addition, a mild hybrid concept is provided which utilizes a smaller electric motor than typical hybrid powertrain systems. Because the electric motor is drivingly engaged with the drive shaft of the transmission, the electric motor/generator is driven at high speed even when the vehicle speed is low so that the electric motor/generator provides more efficient regeneration.

Powertrain system for a hybrid electric vehicle

DOEpatents

Reed, R.G. Jr.; Boberg, E.S.; Lawrie, R.E.; Castaing, F.J.

1999-08-31

A hybrid electric powertrain system is provided including an electric motor/generator drivingly engaged with the drive shaft of a transmission. The electric is utilized for synchronizing the rotation of the drive shaft with the driven shaft during gear shift operations. In addition, a mild hybrid concept is provided which utilizes a smaller electric motor than typical hybrid powertrain systems. Because the electric motor is drivingly engaged with the drive shaft of the transmission, the electric motor/generator is driven at high speed even when the vehicle speed is low so that the electric motor/generator provides more efficient regeneration. 34 figs.

Results and conclusions: perception sensor study for high speed autonomous operations

NASA Astrophysics Data System (ADS)

Schneider, Anne; LaCelle, Zachary; Lacaze, Alberto; Murphy, Karl; Close, Ryan

2016-05-01

Previous research has presented work on sensor requirements, specifications, and testing, to evaluate the feasibility of increasing autonomous vehicle system speeds. Discussions included the theoretical background for determining sensor requirements, and the basic test setup and evaluation criteria for comparing existing and prototype sensor designs. This paper will present and discuss the continuation of this work. In particular, this paper will focus on analyzing the problem via a real-world comparison of various sensor technology testing results, as opposed to previous work that utilized more of a theoretical approach. LADAR/LIDAR, radar, visual, and infrared sensors are considered in this research. Results are evaluated against the theoretical, desired perception specifications. Conclusions for utilizing a suite of perception sensors, to achieve the goal of doubling ground vehicle speeds, is also discussed.

Magnetically-focusing biochip structures for high-speed active biosensing with improved selectivity.

PubMed

Yoo, Haneul; Lee, Dong Jun; Kim, Daesan; Park, Juhun; Chen, Xing; Hong, Seunghun

2018-06-29

We report a magnetically-focusing biochip structure enabling a single layered magnetic trap-and-release cycle for biosensors with an improved detection speed and selectivity. Here, magnetic beads functionalized with specific receptor molecules were utilized to trap target molecules in a solution and transport actively to and away from the sensor surfaces to enhance the detection speed and reduce the non-specific bindings, respectively. Using our method, we demonstrated the high speed detection of IL-13 antigens with the improved detection speed by more than an order of magnitude. Furthermore, the release step in our method was found to reduce the non-specific bindings and improve the selectivity and sensitivity of biosensors. This method is a simple but powerful strategy and should open up various applications such as ultra-fast biosensors for point-of-care services.

Magnetically-focusing biochip structures for high-speed active biosensing with improved selectivity

NASA Astrophysics Data System (ADS)

Yoo, Haneul; Lee, Dong Jun; Kim, Daesan; Park, Juhun; Chen, Xing; Hong, Seunghun

2018-06-01

We report a magnetically-focusing biochip structure enabling a single layered magnetic trap-and-release cycle for biosensors with an improved detection speed and selectivity. Here, magnetic beads functionalized with specific receptor molecules were utilized to trap target molecules in a solution and transport actively to and away from the sensor surfaces to enhance the detection speed and reduce the non-specific bindings, respectively. Using our method, we demonstrated the high speed detection of IL-13 antigens with the improved detection speed by more than an order of magnitude. Furthermore, the release step in our method was found to reduce the non-specific bindings and improve the selectivity and sensitivity of biosensors. This method is a simple but powerful strategy and should open up various applications such as ultra-fast biosensors for point-of-care services.

Research on high-speed railway's vibration analysis checking based on intelligent mobile terminal

NASA Astrophysics Data System (ADS)

Li, Peigang; Xie, Shulin; Zhao, Xuefeng

2017-04-01

Recently, the development of high-speed railway meets the requirement of society booming and it has gradually become the first choice for long-length journey. Since ensuring the safety and stable operation are of great importance to high-speed trains owing to its unique features, vibration analysis checking is one of main means to be adopted. Due to the popularization of Smartphone, in this research, a novel public-participating method to achieve high-speed railway's vibration analysis checking based on smartphone and an inspection application of high-speed railway line built in the intelligent mobile terminal were proposed. Utilizing the accelerometer, gyroscope, GPS and other high-performance sensors which were integrated in smartphone, the application can obtain multiple parameters like acceleration, angle, etc and pinpoint the location. Therefore, through analyzing the acceleration data in time domain and frequency domain using fast Fourier transform, the research compared much of data from monitoring tests under different measure conditions and measuring points. Furthermore, an idea of establishing a system about analysis checking was outlined in paper. It has been validated that the smartphone-based high-speed railway line inspection system is reliable and feasible on the high-speed railway lines. And it has more advantages, such as convenience, low cost and being widely used. Obviously, the research has important practical significance and broad application prospects.

A Synchronization Algorithm and Implementation for High-Speed Block Codes Applications. Part 4

NASA Technical Reports Server (NTRS)

Lin, Shu; Zhang, Yu; Nakamura, Eric B.; Uehara, Gregory T.

1998-01-01

Block codes have trellis structures and decoders amenable to high speed CMOS VLSI implementation. For a given CMOS technology, these structures enable operating speeds higher than those achievable using convolutional codes for only modest reductions in coding gain. As a result, block codes have tremendous potential for satellite trunk and other future high-speed communication applications. This paper describes a new approach for implementation of the synchronization function for block codes. The approach utilizes the output of the Viterbi decoder and therefore employs the strength of the decoder. Its operation requires no knowledge of the signal-to-noise ratio of the received signal, has a simple implementation, adds no overhead to the transmitted data, and has been shown to be effective in simulation for received SNR greater than 2 dB.

Development of Predictive Energy Management Strategies for Hybrid Electric Vehicles

NASA Astrophysics Data System (ADS)

Baker, David

Studies have shown that obtaining and utilizing information about the future state of vehicles can improve vehicle fuel economy (FE). However, there has been a lack of research into the impact of real-world prediction error on FE improvements, and whether near-term technologies can be utilized to improve FE. This study seeks to research the effect of prediction error on FE. First, a speed prediction method is developed, and trained with real-world driving data gathered only from the subject vehicle (a local data collection method). This speed prediction method informs a predictive powertrain controller to determine the optimal engine operation for various prediction durations. The optimal engine operation is input into a high-fidelity model of the FE of a Toyota Prius. A tradeoff analysis between prediction duration and prediction fidelity was completed to determine what duration of prediction resulted in the largest FE improvement. Results demonstrate that 60-90 second predictions resulted in the highest FE improvement over the baseline, achieving up to a 4.8% FE increase. A second speed prediction method utilizing simulated vehicle-to-vehicle (V2V) communication was developed to understand if incorporating near-term technologies could be utilized to further improve prediction fidelity. This prediction method produced lower variation in speed prediction error, and was able to realize a larger FE improvement over the local prediction method for longer prediction durations, achieving up to 6% FE improvement. This study concludes that speed prediction and prediction-informed optimal vehicle energy management can produce FE improvements with real-world prediction error and drive cycle variability, as up to 85% of the FE benefit of perfect speed prediction was achieved with the proposed prediction methods.

Compressed air production with waste heat utilization in industry

NASA Astrophysics Data System (ADS)

Nolting, E.

1984-06-01

The centralized power-heat coupling (PHC) technique using block heating power stations, is presented. Compressed air production in PHC technique with internal combustion engine drive achieves a high degree of primary energy utilization. Cost savings of 50% are reached compared to conventional production. The simultaneous utilization of compressed air and heat is especially interesting. A speed regulated drive via an internal combustion motor gives a further saving of 10% to 20% compared to intermittent operation. The high fuel utilization efficiency ( 80%) leads to a pay off after two years for operation times of 3000 hr.

Application of Multifunctional Doppler LIDAR for Noncontact Track Speed, Distance, and Curvature Assessment

NASA Astrophysics Data System (ADS)

Munoz, Joshua

The primary focus of this research is evaluation of feasibility, applicability, and accuracy of Doppler Light Detection And Ranging (LIDAR) sensors as non-contact means for measuring track speed, distance traveled, and curvature. Speed histories, currently measured with a rotary, wheelmounted encoder, serve a number of useful purposes, one significant use involving derailment investigations. Distance calculation provides a spatial reference system for operators to locate track sections of interest. Railroad curves, using an IMU to measure curvature, are monitored to maintain track infrastructure within regulations. Speed measured with high accuracy leads to highfidelity distance and curvature data through utilization of processor clock rate and left-and rightrail speed differentials during curve navigation, respectively. Wheel-mounted encoders, or tachometers, provide a relatively low-resolution speed profile, exhibit increased noise with increasing speed, and are subject to the inertial behavior of the rail car which affects output data. The IMU used to measure curvature is dependent on acceleration and yaw rate sensitivity and experiences difficulty in low-speed conditions. Preliminary system tests onboard a "Hy-Rail" utility vehicle capable of traveling on rail show speed capture is possible using the rails as the reference moving target and furthermore, obtaining speed profiles from both rails allows for the calculation of speed differentials in curves to estimate degrees curvature. Ground truth distance calibration and curve measurement were also carried out. Distance calibration involved placement of spatial landmarks detected by a sensor to synchronize distance measurements as a pre-processing procedure. Curvature ground truth measurements provided a reference system to confirm measurement results and observe alignment variation throughout a curve. Primary testing occurred onboard a track geometry rail car, measuring rail speed over substantial mileage in various weather conditions, providing highaccuracy data to further calculate distance and curvature along the test routes. Tests results indicate the LIDAR system measures speed at higher accuracy than the encoder, absent of noise influenced by increasing speed. Distance calculation is also high in accuracy, results showing high correlation with encoder and ground truth data. Finally, curvature calculation using speed data is shown to have good correlation with IMU measurements and a resolution capable of revealing localized track alignments. Further investigations involve a curve measurement algorithm and speed calibration method independent from external reference systems, namely encoder and ground truth data. The speed calibration results show a high correlation with speed data from the track geometry vehicle. It is recommended that the study be extended to provide assessment of the LIDAR's sensitivity to car body motion in order to better isolate the embedded behavior in the speed and curvature profiles. Furthermore, in the interest of progressing the system toward a commercially viable unit, methods for self-calibration and pre-processing to allow for fully independent operation is highly encouraged.

Preliminary results from the High Speed Airframe Integration Research project

NASA Technical Reports Server (NTRS)

Coen, Peter G.; Sobieszczanski-Sobieski, Jaroslaw; Dollyhigh, Samuel M.

1992-01-01

A review is presented of the accomplishment of the near term objectives of developing an analysis system and optimization methods during the first year of the NASA Langley High Speed Airframe Integration Research (HiSAIR) project. The characteristics of a Mach 3 HSCT transport have been analyzed utilizing the newly developed process. In addition to showing more detailed information about the aerodynamic and structural coupling for this type of vehicle, this exercise aided in further refining the data requirements for the analysis process.

The Fundamental Principles of High-speed Semi-diesel Engines. Part I: a General Discussion of the Subject of Fuel Injection in Diesel Engines and Detailed Descriptions of Many Types of Injection Nozzles

NASA Technical Reports Server (NTRS)

Buchner,

1926-01-01

Three questions relating to the technical progress in the utilization of heavy oils are discussed. The first question considers solid injection in high-speed automobile engines, the second concerns the development of the hot-bulb engine, and the third question relates to the need for a more thorough investigation of the processes on which the formatation of combustible, rapidly-burning mixtures depend.

Knowledge-Based Manufacturing and Structural Design for a High Speed Civil Transport

NASA Technical Reports Server (NTRS)

Marx, William J.; Mavris, Dimitri N.; Schrage, Daniel P.

1994-01-01

The aerospace industry is currently addressing the problem of integrating manufacturing and design. To address the difficulties associated with using many conventional procedural techniques and algorithms, one feasible way to integrate the two concepts is with the development of an appropriate Knowledge-Based System (KBS). The authors present their reasons for selecting a KBS to integrate design and manufacturing. A methodology for an aircraft producibility assessment is proposed, utilizing a KBS for manufacturing process selection, that addresses both procedural and heuristic aspects of designing and manufacturing of a High Speed Civil Transport (HSCT) wing. A cost model is discussed that would allow system level trades utilizing information describing the material characteristics as well as the manufacturing process selections. Statements of future work conclude the paper.

PEM-PCA: a parallel expectation-maximization PCA face recognition architecture.

PubMed

Rujirakul, Kanokmon; So-In, Chakchai; Arnonkijpanich, Banchar

2014-01-01

Principal component analysis or PCA has been traditionally used as one of the feature extraction techniques in face recognition systems yielding high accuracy when requiring a small number of features. However, the covariance matrix and eigenvalue decomposition stages cause high computational complexity, especially for a large database. Thus, this research presents an alternative approach utilizing an Expectation-Maximization algorithm to reduce the determinant matrix manipulation resulting in the reduction of the stages' complexity. To improve the computational time, a novel parallel architecture was employed to utilize the benefits of parallelization of matrix computation during feature extraction and classification stages including parallel preprocessing, and their combinations, so-called a Parallel Expectation-Maximization PCA architecture. Comparing to a traditional PCA and its derivatives, the results indicate lower complexity with an insignificant difference in recognition precision leading to high speed face recognition systems, that is, the speed-up over nine and three times over PCA and Parallel PCA.

Double Helical Gear Performance Results in High Speed Gear Trains

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Ehinger, Ryan; Sinusas, Eric; Kilmain, Charles

2009-01-01

The operation of high speed gearing systems in the transmissions of tiltrotor aircraft has an effect on overall propulsion system efficiency. Recent work has focused on many aspects of high-speed helical gear trains as would be used in tiltrotor aircraft such as operational characteristics, comparison of analytical predictions to experimental data and the affect of superfinishing on transmission performance. Baseline tests of an aerospace quality system have been conducted in the NASA Glenn High-Speed Helical Gear Train Test Facility and have been described in earlier studies. These earlier tests had utilized single helical gears. The results that will be described in this study are those attained using double helical gears. This type of gear mesh can be configured in this facility to either pump the air-oil environment from the center gap between the meshing gears to the outside of tooth ends or in the reverse direction. Tests were conducted with both inward and outward air-oil pumping directions. Results are compared to the earlier baseline results of single helical gears.

Double Helical Gear Performance Results in High Speed Gear Trains

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Ehinger, Ryan; Sinusas, Eric; Kilmain, Charles

2010-01-01

The operation of high speed gearing systems in the transmissions of tiltrotor aircraft has an effect on overall propulsion system efficiency. Recent work has focused on many aspects of high-speed helical gear trains as would be used in tiltrotor aircraft such as operational characteristics, comparison of analytical predictions to experimental data and the affect of superfinishing on transmission performance. Baseline tests of an aerospace quality system have been conducted in the NASA Glenn High-Speed Helical Gear Train Test Facility and have been described in earlier studies. These earlier tests had utilized single helical gears. The results that will be described in this study are those attained using double helical gears. This type of gear mesh can be configured in this facility to either pump the air-oil environment from the center gap between the meshing gears to the outside of tooth ends or in the reverse direction. Tests were conducted with both inward and outward air-oil pumping directions. Results are compared to the earlier baseline results of single helical gears.

Investigation of advanced pre- and post-equalization schemes in high-order CAP modulation based high-speed indoor VLC transmission system

NASA Astrophysics Data System (ADS)

Wang, Yiguang; Chi, Nan

2016-10-01

Light emitting diodes (LEDs) based visible light communication (VLC) has been considered as a promising technology for indoor high-speed wireless access, due to its unique advantages, such as low cost, license free and high security. To achieve high-speed VLC transmission, carrierless amplitude and phase (CAP) modulation has been utilized for its lower complexity and high spectral efficiency. Moreover, to compensate the linear and nonlinear distortions such as frequency attenuation, sampling time offset, LED nonlinearity etc., series of pre- and post-equalization schemes should be employed in high-speed VLC systems. In this paper, we make an investigation on several advanced pre- and postequalization schemes for high-order CAP modulation based VLC systems. We propose to use a weighted preequalization technique to compensate the LED frequency attenuation. In post-equalization, a hybrid post equalizer is proposed, which consists of a linear equalizer, a Volterra series based nonlinear equalizer, and a decision-directed least mean square (DD-LMS) equalizer. Modified cascaded multi-modulus algorithm (M-CMMA) is employed to update the weights of the linear and the nonlinear equalizer, while DD-LMS can further improve the performance after the preconvergence. Based on high-order CAP modulation and these equalization schemes, we have experimentally demonstrated a 1.35-Gb/s, a 4.5-Gb/s and a 8-Gb/s high-speed indoor VLC transmission systems. The results show the benefit and feasibility of the proposed equalization schemes for high-speed VLC systems.

Repeatable, accurate, and high speed multi-level programming of memristor 1T1R arrays for power efficient analog computing applications.

PubMed

Merced-Grafals, Emmanuelle J; Dávila, Noraica; Ge, Ning; Williams, R Stanley; Strachan, John Paul

2016-09-09

Beyond use as high density non-volatile memories, memristors have potential as synaptic components of neuromorphic systems. We investigated the suitability of tantalum oxide (TaOx) transistor-memristor (1T1R) arrays for such applications, particularly the ability to accurately, repeatedly, and rapidly reach arbitrary conductance states. Programming is performed by applying an adaptive pulsed algorithm that utilizes the transistor gate voltage to control the SET switching operation and increase programming speed of the 1T1R cells. We show the capability of programming 64 conductance levels with <0.5% average accuracy using 100 ns pulses and studied the trade-offs between programming speed and programming error. The algorithm is also utilized to program 16 conductance levels on a population of cells in the 1T1R array showing robustness to cell-to-cell variability. In general, the proposed algorithm results in approximately 10× improvement in programming speed over standard algorithms that do not use the transistor gate to control memristor switching. In addition, after only two programming pulses (an initialization pulse followed by a programming pulse), the resulting conductance values are within 12% of the target values in all cases. Finally, endurance of more than 10(6) cycles is shown through open-loop (single pulses) programming across multiple conductance levels using the optimized gate voltage of the transistor. These results are relevant for applications that require high speed, accurate, and repeatable programming of the cells such as in neural networks and analog data processing.

Design, manufacture and spin test of high contact ratio helicopter transmission utilizing Self-Aligning Bearingless Planetary (SABP)

NASA Technical Reports Server (NTRS)

Folenta, Dezi; Lebo, William

1988-01-01

A 450 hp high ratio Self-Aligning Bearingless Planetary (SABP) for a helicopter application was designed, manufactured, and spin tested under NASA contract NAS3-24539. The objective of the program was to conduct research and development work on a high contact ratio helical gear SABP to reduce weight and noise and to improve efficiency. The results accomplished include the design, manufacturing, and no-load spin testing of two prototype helicopter transmissions, rated at 450 hp with an input speed of 35,000 rpm and an output speed of 350 rpm. The weight power density ratio of these gear units is 0.33 lb hp. The measured airborne noise at 35,000 rpm input speed and light load is 94 dB at 5 ft. The high speed, high contact ratio SABP transmission appears to be significantly lighter and quieter than comtemporary helicopter transmissions. The concept of the SABP is applicable not only to high ratio helicopter type transmissions but also to other rotorcraft and aircraft propulsion systems.

Comparisons of two-dimensional shock-expansion theory with experimental aerodynamic data for delta-planform wings at high supersonic speeds

NASA Technical Reports Server (NTRS)

Jernell, L. S.

1974-01-01

An investigation has been conducted to explore the potential for optimizing airfoil shape at high supersonic speeds by utilizing the two-dimensional shock-expansion method. Theoretical and experimental force and moment coefficients are compared for four delta-planform semispan wings having a leading-edge sweep angle of 65 deg and incorporating modified diamond airfoils with a thickness-chord ratio of 0.06. The wings differ only in airfoil maximum-thickness position and camber. The experimental data are obtained at Mach numbers of 3.95 and 4.63 and at a Reynolds number of 9.84 million per meter. A relatively simple method is developed for predicting, in terms of lift-drag ratio, the optimum modified diamond airfoil at high supersonic and hypersonic speeds.

Robust multiple cue fusion-based high-speed and nonrigid object tracking algorithm for short track speed skating

NASA Astrophysics Data System (ADS)

Liu, Chenguang; Cheng, Heng-Da; Zhang, Yingtao; Wang, Yuxuan; Xian, Min

2016-01-01

This paper presents a methodology for tracking multiple skaters in short track speed skating competitions. Nonrigid skaters move at high speed with severe occlusions happening frequently among them. The camera is panned quickly in order to capture the skaters in a large and dynamic scene. To automatically track the skaters and precisely output their trajectories becomes a challenging task in object tracking. We employ the global rink information to compensate camera motion and obtain the global spatial information of skaters, utilize random forest to fuse multiple cues and predict the blob of each skater, and finally apply a silhouette- and edge-based template-matching and blob-evolving method to labelling pixels to a skater. The effectiveness and robustness of the proposed method are verified through thorough experiments.

Cost Allocation

DOT National Transportation Integrated Search

2000-03-09

The Texas Department of Transportations (TxDOT) "smart highway" project, called TransGuide, scheduled to go on line in 1995 in San Antonio, utilizes high speed computer technology to help drivers anticipate traffic conditions-- in an effort to inc...

A minimal SATA III Host Controller based on FPGA

NASA Astrophysics Data System (ADS)

Liu, Hailiang

2018-03-01

SATA (Serial Advanced Technology Attachment) is an advanced serial bus which has a outstanding performance in transmitting high speed real-time data applied in Personal Computers, Financial Industry, astronautics and aeronautics, etc. In this express, a minimal SATA III Host Controller based on Xilinx Kintex 7 serial FPGA is designed and implemented. Compared to the state-of-art, registers utilization are reduced 25.3% and LUTs utilization are reduced 65.9%. According to the experimental results, the controller works precisely and steady with the reading bandwidth of up to 536 MB per second and the writing bandwidth of up to 512 MB per second, both of which are close to the maximum bandwidth of the SSD(Solid State Disk) device. The host controller is very suitable for high speed data transmission and mass data storage.

Technology Assessment for Large Vertical-Lift Transport Tiltrotors

NASA Technical Reports Server (NTRS)

Germanowski, Peter J.; Stille, Brandon L.; Strauss, Michael P.

2010-01-01

The technical community has identified rotor efficiency as a critical enabling technology for large vertical-lift transport (LVLT) rotorcraft. The size and performance of LVLT aircraft will be far beyond current aircraft capabilities, enabling a transformational change in cargo transport effectiveness. Two candidate approaches for achieving high efficiency were considered for LVLT applications: a variable-diameter tiltrotor (VDTR) and a variable-speed tiltrotor (VSTR); the former utilizes variable-rotor geometry and the latter utilizes variable-rotor speed. Conceptual aircraft designs were synthesized for the VDTR and VSTR and compared to a conventional tiltrotor (CTR). The aircraft were optimized to a common objective function and bounded by a set of physical- and requirements-driven constraints. The resulting aircraft were compared for weight, size, performance, handling qualities, and other attributes. These comparisons established a measure of the relative merits of the variable-diameter and -speed rotor systems as enabling technologies for LVLT capability.

Investigation of self-excited induction generators for wind turbine applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muljadi, E.; Butterfield, C.P.; Sallan, J.

2000-02-28

The use of squirrel-cage induction machines in wind generation is widely accepted as a generator of choice. The squirrel-cage induction machine is simple, reliable, cheap, lightweight, and requires very little maintenance. Generally, the induction generator is connected to the utility at constant frequency. With a constant frequency operation, the induction generator operates at practically constant speed (small range of slip). The wind turbine operates in optimum efficiency only within a small range of wind speed variation. The variable-speed operation allows an increase in energy captured and reduces both the torque peaks in the drive train and the power fluctuations sentmore » to the utility. In variable-speed operation, an induction generator needs an interface to convert the variable frequency output of the generator to the fixed frequency at the utility. This interface can be simplified by using a self-excited generator because a simple diode bridge is required to perform the ac/dc conversion. The subsequent dc/ac conversion can be performed using different techniques. The use of a thyristor bridge is readily available for large power conversion and has a lower cost and higher reliability. The firing angle of the inverter bridge can be controlled to track the optimum power curve of the wind turbine. With only diodes and thyristors used in power conversion, the system can be scaled up to a very high voltage and high power applications. This paper analyzes the operation of such a system applied to a 1/3-hp self-excited induction generator. It includes the simulations and tests performed for the different excitation configurations.« less

High-Speed Data Recorder for Space, Geodesy, and Other High-Speed Recording Applications

NASA Technical Reports Server (NTRS)

Taveniku, Mikael

2013-01-01

A high-speed data recorder and replay equipment has been developed for reliable high-data-rate recording to disk media. It solves problems with slow or faulty disks, multiple disk insertions, high-altitude operation, reliable performance using COTS hardware, and long-term maintenance and upgrade path challenges. The current generation data recor - ders used within the VLBI community are aging, special-purpose machines that are both slow (do not meet today's requirements) and are very expensive to maintain and operate. Furthermore, they are not easily upgraded to take advantage of commercial technology development, and are not scalable to multiple 10s of Gbit/s data rates required by new applications. The innovation provides a softwaredefined, high-speed data recorder that is scalable with technology advances in the commercial space. It maximally utilizes current technologies without being locked to a particular hardware platform. The innovation also provides a cost-effective way of streaming large amounts of data from sensors to disk, enabling many applications to store raw sensor data and perform post and signal processing offline. This recording system will be applicable to many applications needing realworld, high-speed data collection, including electronic warfare, softwaredefined radar, signal history storage of multispectral sensors, development of autonomous vehicles, and more.

Aerodynamic Design of a Dual-Flow Mach 7 Hypersonic Inlet System for a Turbine-Based Combined-Cycle Hypersonic Propulsion System

NASA Technical Reports Server (NTRS)

Sanders, Bobby W.; Weir, Lois J.

2008-01-01

A new hypersonic inlet for a turbine-based combined-cycle (TBCC) engine has been designed. This split-flow inlet is designed to provide flow to an over-under propulsion system with turbofan and dual-mode scramjet engines for flight from takeoff to Mach 7. It utilizes a variable-geometry ramp, high-speed cowl lip rotation, and a rotating low-speed cowl that serves as a splitter to divide the flow between the low-speed turbofan and the high-speed scramjet and to isolate the turbofan at high Mach numbers. The low-speed inlet was designed for Mach 4, the maximum mode transition Mach number. Integration of the Mach 4 inlet into the Mach 7 inlet imposed significant constraints on the low-speed inlet design, including a large amount of internal compression. The inlet design was used to develop mechanical designs for two inlet mode transition test models: small-scale (IMX) and large-scale (LIMX) research models. The large-scale model is designed to facilitate multi-phase testing including inlet mode transition and inlet performance assessment, controls development, and integrated systems testing with turbofan and scramjet engines.

Large-Scale Advanced Prop-Fan (LAP) pitch change actuator and control design report

NASA Technical Reports Server (NTRS)

Schwartz, R. A.; Carvalho, P.; Cutler, M. J.

1986-01-01

In recent years, considerable attention has been directed toward improving aircraft fuel consumption. Studies have shown that the high inherent efficiency previously demonstrated by low speed turboprop propulsion systems may now be extended to today's higher speed aircraft if advanced high-speed propeller blades having thin airfoils and aerodynamic sweep are utilized. Hamilton Standard has designed a 9-foot diameter single-rotation Large-Scale Advanced Prop-Fan (LAP) which will be tested on a static test stand, in a high speed wind tunnel and on a research aircraft. The major objective of this testing is to establish the structural integrity of large-scale Prop-Fans of advanced construction in addition to the evaluation of aerodynamic performance and aeroacoustic design. This report describes the operation, design features and actual hardware of the (LAP) Prop-Fan pitch control system. The pitch control system which controls blade angle and propeller speed consists of two separate assemblies. The first is the control unit which provides the hydraulic supply, speed governing and feather function for the system. The second unit is the hydro-mechanical pitch change actuator which directly changes blade angle (pitch) as scheduled by the control.

Forward-biased nanophotonic detector for ultralow-energy dissipation receiver

NASA Astrophysics Data System (ADS)

Nozaki, Kengo; Matsuo, Shinji; Fujii, Takuro; Takeda, Koji; Shinya, Akihiko; Kuramochi, Eiichi; Notomi, Masaya

2018-04-01

Generally, reverse-biased photodetectors (PDs) are used for high-speed optical receivers. The forward voltage region is only utilized in solar-cells, and this photovoltaic operation would not be concurrently obtained with high efficiency and high speed operation. Here we report that photonic-crystal waveguide PDs enable forward-biased high-speed operation at 40 Gbit/s with keeping high responsivity (0.88 A/W). Within our knowledge, this is the first demonstration of the forward-biased PDs with high responsivity. This achievement is attributed to the ultracompactness of our PD and the strong light confinement within the absorber and depleted regions, thereby enabling efficient photo-carrier generation and fast extraction. This result indicates that it is possible to construct a high-speed and ultracompact photo-receiver without an electrical amplifier nor an external bias circuit. Since there is no electrical energy required, our estimation shows that the consumption energy is just the optical energy of the injected signal pulse which is about 1 fJ/bit. Hence, it will lead to an ultimately efficient and highly integrable optical-to-electrical converter in a chip, which will be a key ingredient for dense nanophotonic communication and processors.

A programmable computational image sensor for high-speed vision

NASA Astrophysics Data System (ADS)

Yang, Jie; Shi, Cong; Long, Xitian; Wu, Nanjian

2013-08-01

In this paper we present a programmable computational image sensor for high-speed vision. This computational image sensor contains four main blocks: an image pixel array, a massively parallel processing element (PE) array, a row processor (RP) array and a RISC core. The pixel-parallel PE is responsible for transferring, storing and processing image raw data in a SIMD fashion with its own programming language. The RPs are one dimensional array of simplified RISC cores, it can carry out complex arithmetic and logic operations. The PE array and RP array can finish great amount of computation with few instruction cycles and therefore satisfy the low- and middle-level high-speed image processing requirement. The RISC core controls the whole system operation and finishes some high-level image processing algorithms. We utilize a simplified AHB bus as the system bus to connect our major components. Programming language and corresponding tool chain for this computational image sensor are also developed.

Evaluation of ATV Track Systems for Winter Mountain Operations

DTIC Science & Technology

2011-06-01

charge utile. Importance des résultats et perspectives : Selon ces essais limités, comparativement à une motoneige moderne, les VTT à chenilles...of this document, but the products seem similar in design , with subtle differences in frame, suspension, track depth, etc. Each of the companies sell...because the transmission of this vehicle seems to be designed for high-speed operation, rather than low-speed torque. It should also be noted that the

Cryogenic, high speed, turbopump bearing cooling requirements

NASA Technical Reports Server (NTRS)

Dolan, Fred J.; Gibson, Howard G.; Cannon, James L.; Cody, Joe C.

1988-01-01

Although the Space Shuttle Main Engine (SSME) has repeatedly demonstrated the capability to perform during launch, the High Pressure Oxidizer Turbopump (HPOTP) main shaft bearings have not met their 7.5 hour life requirement. A tester is being employed to provide the capability of subjecting full scale bearings and seals to speeds, loads, propellants, temperatures, and pressures which simulate engine operating conditions. The tester design permits much more elaborate instrumentation and diagnostics than could be accommodated in an SSME turbopump. Tests were made to demonstrate the facilities; and the devices' capabilities, to verify the instruments in its operating environment and to establish a performance baseline for the flight type SSME HPOTP Turbine Bearing design. Bearing performance data from tests are being utilized to generate: (1) a high speed, cryogenic turbopump bearing computer mechanical model, and (2) a much improved, very detailed thermal model to better understand bearing internal operating conditions. Parametric tests were also made to determine the effects of speed, axial loads, coolant flow rate, and surface finish degradation on bearing performance.

Low speed phaselock speed control system. [for brushless dc motor

NASA Technical Reports Server (NTRS)

Fulcher, R. W.; Sudey, J. (Inventor)

1975-01-01

A motor speed control system for an electronically commutated brushless dc motor is provided which includes a phaselock loop with bidirectional torque control for locking the frequency output of a high density encoder, responsive to actual speed conditions, to a reference frequency signal, corresponding to the desired speed. The system includes a phase comparator, which produces an output in accordance with the difference in phase between the reference and encoder frequency signals, and an integrator-digital-to-analog converter unit, which converts the comparator output into an analog error signal voltage. Compensation circuitry, including a biasing means, is provided to convert the analog error signal voltage to a bidirectional error signal voltage which is utilized by an absolute value amplifier, rotational decoder, power amplifier-commutators, and an arrangement of commutation circuitry.

Design and Evaluation of a Dynamic Dilemma Zone System for a High Speed Rural Intersection

DOT National Transportation Integrated Search

2012-08-01

The goal of this research was to develop a system that utilizes the dynamic detection technology and : to evaluate the performance of this system. The first step of this study was to select an intersection : experiencing a high frequency of crashes t...

Influence of Lift Offset on Rotorcraft Performance

NASA Technical Reports Server (NTRS)

Johnson, Wayne

2009-01-01

The influence of lift offset on the performance of several rotorcraft configurations is explored. A lift-offset rotor, or advancing blade concept, is a hingeless rotor that can attain good efficiency at high speed by operating with more lift on the advancing side than on the retreating side of the rotor disk. The calculated performance capability of modern-technology coaxial rotors utilizing a lift offset is examined, including rotor performance optimized for hover and high-speed cruise. The ideal induced power loss of coaxial rotors in hover and twin rotors in forward flight is presented. The aerodynamic modeling requirements for performance calculations are evaluated, including wake and drag models for the high-speed flight condition. The influence of configuration on the performance of rotorcraft with lift-offset rotors is explored, considering tandem and side-by-side rotorcraft as well as wing-rotor lift share.

Influence of Lift Offset on Rotorcraft Performance

NASA Technical Reports Server (NTRS)

Johnson, Wayne

2008-01-01

The influence of lift offset on the performance of several rotorcraft configurations is explored. A lift-offset rotor, or advancing blade concept, is a hingeless rotor that can attain good efficiency at high speed, by operating with more lift on the advancing side than on the retreating side of the rotor disk. The calculated performance capability of modern-technology coaxial rotors utilizing a lift offset is examined, including rotor performance optimized for hover and high-speed cruise. The ideal induced power loss of coaxial rotors in hover and twin rotors in forward flight is presented. The aerodynamic modeling requirements for performance calculations are evaluated, including wake and drag models for the high speed flight condition. The influence of configuration on the performance of rotorcraft with lift-offset rotors is explored, considering tandem and side-by-side rotorcraft as well as wing-rotor lift share.

The numerical simulation of a high-speed axial flow compressor

NASA Technical Reports Server (NTRS)

Mulac, Richard A.; Adamczyk, John J.

1991-01-01

The advancement of high-speed axial-flow multistage compressors is impeded by a lack of detailed flow-field information. Recent development in compressor flow modeling and numerical simulation have the potential to provide needed information in a timely manner. The development of a computer program is described to solve the viscous form of the average-passage equation system for multistage turbomachinery. Programming issues such as in-core versus out-of-core data storage and CPU utilization (parallelization, vectorization, and chaining) are addressed. Code performance is evaluated through the simulation of the first four stages of a five-stage, high-speed, axial-flow compressor. The second part addresses the flow physics which can be obtained from the numerical simulation. In particular, an examination of the endwall flow structure is made, and its impact on blockage distribution assessed.

Fiber optic interferometry for industrial process monitoring and control applications

NASA Astrophysics Data System (ADS)

Marcus, Michael A.

2002-02-01

Over the past few years we have been developing applications for a high-resolution (sub-micron accuracy) fiber optic coupled dual Michelson interferometer-based instrument. It is being utilized in a variety of applications including monitoring liquid layer thickness uniformity on coating hoppers, film base thickness uniformity measurement, digital camera focus assessment, optical cell path length assessment and imager and wafer surface profile mapping. The instrument includes both coherent and non-coherent light sources, custom application dependent optical probes and sample interfaces, a Michelson interferometer, custom electronics, a Pentium-based PC with data acquisition cards and LabWindows CVI or LabView based application specific software. This paper describes the development evolution of this instrument platform and applications highlighting robust instrument design, hardware, software, and user interfaces development. The talk concludes with a discussion of a new high-speed instrument configuration, which can be utilized for high speed surface profiling and as an on-line web thickness gauge.

Civil propulsion technology for the next twenty-five years

NASA Technical Reports Server (NTRS)

Rosen, Robert; Facey, John R.

1987-01-01

The next twenty-five years will see major advances in civil propulsion technology that will result in completely new aircraft systems for domestic, international, commuter and high-speed transports. These aircraft will include advanced aerodynamic, structural, and avionic technologies resulting in major new system capabilities and economic improvements. Propulsion technologies will include high-speed turboprops in the near term, very high bypass ratio turbofans, high efficiency small engines and advanced cycles utilizing high temperature materials for high-speed propulsion. Key fundamental enabling technologies include increased temperature capability and advanced design methods. Increased temperature capability will be based on improved composite materials such as metal matrix, intermetallics, ceramics, and carbon/carbon as well as advanced heat transfer techniques. Advanced design methods will make use of advances in internal computational fluid mechanics, reacting flow computation, computational structural mechanics and computational chemistry. The combination of advanced enabling technologies, new propulsion concepts and advanced control approaches will provide major improvements in civil aircraft.

IMAGE: A Design Integration Framework Applied to the High Speed Civil Transport

NASA Technical Reports Server (NTRS)

Hale, Mark A.; Craig, James I.

1993-01-01

Effective design of the High Speed Civil Transport requires the systematic application of design resources throughout a product's life-cycle. Information obtained from the use of these resources is used for the decision-making processes of Concurrent Engineering. Integrated computing environments facilitate the acquisition, organization, and use of required information. State-of-the-art computing technologies provide the basis for the Intelligent Multi-disciplinary Aircraft Generation Environment (IMAGE) described in this paper. IMAGE builds upon existing agent technologies by adding a new component called a model. With the addition of a model, the agent can provide accountable resource utilization in the presence of increasing design fidelity. The development of a zeroth-order agent is used to illustrate agent fundamentals. Using a CATIA(TM)-based agent from previous work, a High Speed Civil Transport visualization system linking CATIA, FLOPS, and ASTROS will be shown. These examples illustrate the important role of the agent technologies used to implement IMAGE, and together they demonstrate that IMAGE can provide an integrated computing environment for the design of the High Speed Civil Transport.

PCIE interface design for high-speed image storage system based on SSD

NASA Astrophysics Data System (ADS)

Wang, Shiming

2015-02-01

This paper proposes and implements a standard interface of miniaturized high-speed image storage system, which combines PowerPC with FPGA and utilizes PCIE bus as the high speed switching channel. Attached to the PowerPC, mSATA interface SSD(Solid State Drive) realizes RAID3 array storage. At the same time, a high-speed real-time image compression patent IP core also can be embedded in FPGA, which is in the leading domestic level with compression rate and image quality, making that the system can record higher image data rate or achieve longer recording time. The notebook memory card buckle type design is used in the mSATA interface SSD, which make it possible to complete the replacement in 5 seconds just using single hand, thus the total length of repeated recordings is increased. MSI (Message Signaled Interrupts) interruption guarantees the stability and reliability of continuous DMA transmission. Furthermore, only through the gigabit network, the remote display, control and upload to backup function can be realized. According to an optional 25 frame/s or 30 frame/s, upload speeds can be up to more than 84 MB/s. Compared with the existing FLASH array high-speed memory systems, it has higher degree of modularity, better stability and higher efficiency on development, maintenance and upgrading. Its data access rate is up to 300MB/s, realizing the high speed image storage system miniaturization, standardization and modularization, thus it is fit for image acquisition, storage and real-time transmission to server on mobile equipment.

Application of high speed machining technology in aviation

NASA Astrophysics Data System (ADS)

Bałon, Paweł; Szostak, Janusz; Kiełbasa, Bartłomiej; Rejman, Edward; Smusz, Robert

2018-05-01

Aircraft structures are exposed to many loads during their working lifespan. Every particular action made during a flight is composed of a series of air movements which generate various aircraft loads. The most rigorous requirement which modern aircraft structures must fulfill is to maintain their high durability and reliability. This requirement involves taking many restrictions into account during the aircraft design process. The most important factor is the structure's overall mass, which has a crucial impact on both utility properties and cost-effectiveness. This makes aircraft one of the most complex results of modern technology. Additionally, there is currently an increasing utilization of high strength aluminum alloys, which requires the implementation of new manufacturing processes. High Speed Machining technology (HSM) is currently one of the most important machining technologies used in the aviation industry, especially in the machining of aluminium alloys. The primary difference between HSM and other milling techniques is the ability to select cutting parameters - depth of the cut layer, feed rate, and cutting speed in order to simultaneously ensure high quality, precision of the machined surface, and high machining efficiency, all of which shorten the manufacturing process of the integral components. In this paper, the authors explain the implementation of the HSM method in integral aircraft constructions. It presents the method of the airframe manufacturing method, and the final results. The HSM method is compared to the previous method where all subcomponents were manufactured by bending and forming processes, and then, they were joined by riveting.

Compact high-speed scanning lidar system

NASA Astrophysics Data System (ADS)

Dickinson, Cameron; Hussein, Marwan; Tripp, Jeff; Nimelman, Manny; Koujelev, Alexander

2012-06-01

The compact High Speed Scanning Lidar (HSSL) was designed to meet the requirements for a rover GN&C sensor. The eye-safe HSSL's fast scanning speed, low volume and low power, make it the ideal choice for a variety of real-time and non-real-time applications including: 3D Mapping; Vehicle guidance and Navigation; Obstacle Detection; Orbiter Rendezvous; Spacecraft Landing / Hazard Avoidance. The HSSL comprises two main hardware units: Sensor Head and Control Unit. In a rover application, the Sensor Head mounts on the top of the rover while the Control Unit can be mounted on the rover deck or within its avionics bay. An Operator Computer is used to command the lidar and immediately display the acquired scan data. The innovative lidar design concept was a result of an extensive trade study conducted during the initial phase of an exploration rover program. The lidar utilizes an innovative scanner coupled with a compact fiber laser and high-speed timing electronics. Compared to existing compact lidar systems, distinguishing features of the HSSL include its high accuracy, high resolution, high refresh rate and large field of view. Other benefits of this design include the capability to quickly configure scan settings to fit various operational modes.

A general high-speed laser drilling method for nonmetal thin material

NASA Astrophysics Data System (ADS)

Cai, Zhijian; Xu, Guangsheng; Xu, Zhou; Xu, Zhiqiang

2013-05-01

Many nonmetal film products, such as herbal plaster, medical adhesive tape and farm plastic film, require drilling dense small holes to enhance the permeability without affecting the appearance. For many medium and small enterprises, a low-cost, high-speed laser drilling machine with the ability of processing different kinds of nonmetal material is highly demanded. In this paper, we proposed a general purpose high-speed laser drilling method for micro-hole production on thin nonmetal film. The system utilizes a rotating polygonal mirror to perform high-speed laser scan, which is simpler and more efficient than the oscillating mirror scan. In this system, an array of closepacked paraboloid mirrors is mounted on the laser scan track to focus the high-power laser onto the material sheet, which could produce up to twenty holes in a single scan. The design of laser scan and focusing optics is optimized to obtain the best holes' quality, and the mirrors can be flexibly adjusted to get different drilling parameters. The use of rotating polygonal mirror scan and close-packed mirror array focusing greatly improves the drilling productivity to enable the machine producing thirty thousand holes per minute. With proper design, the hold uniformity can also get improved. In this paper, the detailed optical and mechanical design is illustrated, the high-speed laser drilling principle is introduced and the preliminary experimental results are presented.

Flexible All-Digital Receiver for Bandwidth Efficient Modulations

NASA Technical Reports Server (NTRS)

Gray, Andrew; Srinivasan, Meera; Simon, Marvin; Yan, Tsun-Yee

2000-01-01

An all-digital high data rate parallel receiver architecture developed jointly by Goddard Space Flight Center and the Jet Propulsion Laboratory is presented. This receiver utilizes only a small number of high speed components along with a majority of lower speed components operating in a parallel frequency domain structure implementable in CMOS, and can currently process up to 600 Mbps with standard QPSK modulation. Performance results for this receiver for bandwidth efficient QPSK modulation schemes such as square-root raised cosine pulse shaped QPSK and Feher's patented QPSK are presented, demonstrating the flexibility of the receiver architecture.

An energy efficient and high speed architecture for convolution computing based on binary resistive random access memory

NASA Astrophysics Data System (ADS)

Liu, Chen; Han, Runze; Zhou, Zheng; Huang, Peng; Liu, Lifeng; Liu, Xiaoyan; Kang, Jinfeng

2018-04-01

In this work we present a novel convolution computing architecture based on metal oxide resistive random access memory (RRAM) to process the image data stored in the RRAM arrays. The proposed image storage architecture shows performances of better speed-device consumption efficiency compared with the previous kernel storage architecture. Further we improve the architecture for a high accuracy and low power computing by utilizing the binary storage and the series resistor. For a 28 × 28 image and 10 kernels with a size of 3 × 3, compared with the previous kernel storage approach, the newly proposed architecture shows excellent performances including: 1) almost 100% accuracy within 20% LRS variation and 90% HRS variation; 2) more than 67 times speed boost; 3) 71.4% energy saving.

An improved fast acquisition phase frequency detector for high speed phase-locked loops

NASA Astrophysics Data System (ADS)

Zhang, Lei; Wang, Zongmin; Zhang, Tieliang; Peng, Xinmang

2018-04-01

Phase-locked loops (PLL) have been widely applied in many high-speed designs, such as microprocessors or communication systems. In this paper, an improved fast acquisition phase frequency detector for high speed phase-locked loops is proposed. An improved structure based on dynamic latch is used to eliminate the non-ideal effect such as dead zone and blind zone. And frequency dividers are utilized to vastly extend the phase difference detection range and enhance the operation frequency of the PLL. Proposed PFD has been implemented in 65nm CMOS technology, which occupies an area of 0.0016mm2 and consumes 1.5mW only. Simulation results demonstrate that maximum operation frequency can be up to 5GHz. In addition, the acquisition time of PLL using proposed PFD is 1.0us which is 2.6 times faster than that of the PLL using latch-based PFD without divider.

A Study Of High Speed Friction Behavior Under Elastic Loading Conditions

NASA Astrophysics Data System (ADS)

Crawford, P. J.; Hammerberg, J. E.

2005-03-01

The role of interfacial dynamics under high strain-rate conditions is an important constitutive relationship in modern modeling and simulation studies of dynamic events (<100 μs in length). The frictional behavior occurring at the interface between two metal surfaces under high elastic loading and sliding speed conditions is studied using the Rotating Barrel Gas Gun (RBGG) facility. The RBGG utilizes a low-pressure gas gun to propel a rotating annular projectile towards an annular target rod. Upon striking the target, the projectile imparts both an axial and a torsional impulse into the target. Resulting elastic waves are measured using strain gauges attached to the target rod. The kinetic coefficient of friction is obtained through an analysis of the resulting strain wave data. Experiments performed using Cu/Cu, Cu/Stainless steel and Cu/Al interfaces provide some insight into the kinetic coefficient of friction behavior at varying sliding speeds and impact loads.

Applications of Endothermic Reaction Technology to the High Speed Civil Transport

NASA Technical Reports Server (NTRS)

Glickstein, Marvin R.; Spadaccini, Louis J.

1998-01-01

The success of strategies for controlling emissions and enhancing performance in High Speed Research applications may be Increased by more effective utilization of the heat sink afforded by the fuel in the vehicle thermal management system. This study quantifies the potential benefits associated with the use of supercritical preheating and endothermic cracking of let fuel prior to combustion to enhance the thermal management capabilities of the propulsion systems in the High Speed Civil Transport (HSCT). A fuel-cooled thermal management system, consisting of plate-fin heat exchangers and a small auxiliary compressor, is defined for the HSCT, Integrated with the engine, and an assessment of the effect on engine performance, weight, and operating cost is performed. The analysis indicates significant savings due a projected improvement in fuel economy, and the potential for additional benefit if the cycle is modified to take full advantage of all the heat sink available in the fuel.

MOD-0A 200 kW wind turbine generator design and analysis report

NASA Astrophysics Data System (ADS)

Anderson, T. S.; Bodenschatz, C. A.; Eggers, A. G.; Hughes, P. S.; Lampe, R. F.; Lipner, M. H.; Schornhorst, J. R.

1980-08-01

The design, analysis, and initial performance of the MOD-OA 200 kW wind turbine generator at Clayton, NM is documented. The MOD-OA was designed and built to obtain operation and performance data and experience in utility environments. The project requirements, approach, system description, design requirements, design, analysis, system tests, installation, safety considerations, failure modes and effects analysis, data acquisition, and initial performance for the wind turbine are discussed. The design and analysis of the rotor, drive train, nacelle equipment, yaw drive mechanism and brake, tower, foundation, electricl system, and control systems are presented. The rotor includes the blades, hub, and pitch change mechanism. The drive train includes the low speed shaft, speed increaser, high speed shaft, and rotor brake. The electrical system includes the generator, switchgear, transformer, and utility connection. The control systems are the blade pitch, yaw, and generator control, and the safety system. Manual, automatic, and remote control are discussed. Systems analyses on dynamic loads and fatigue are presented.

MOD-0A 200 kW wind turbine generator design and analysis report

NASA Technical Reports Server (NTRS)

Anderson, T. S.; Bodenschatz, C. A.; Eggers, A. G.; Hughes, P. S.; Lampe, R. F.; Lipner, M. H.; Schornhorst, J. R.

1980-01-01

The design, analysis, and initial performance of the MOD-OA 200 kW wind turbine generator at Clayton, NM is documented. The MOD-OA was designed and built to obtain operation and performance data and experience in utility environments. The project requirements, approach, system description, design requirements, design, analysis, system tests, installation, safety considerations, failure modes and effects analysis, data acquisition, and initial performance for the wind turbine are discussed. The design and analysis of the rotor, drive train, nacelle equipment, yaw drive mechanism and brake, tower, foundation, electricl system, and control systems are presented. The rotor includes the blades, hub, and pitch change mechanism. The drive train includes the low speed shaft, speed increaser, high speed shaft, and rotor brake. The electrical system includes the generator, switchgear, transformer, and utility connection. The control systems are the blade pitch, yaw, and generator control, and the safety system. Manual, automatic, and remote control are discussed. Systems analyses on dynamic loads and fatigue are presented.

Simulation of detonation of ammonium nitrate fuel oil mixture confined by aluminum: edge angles for DSD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Short, Mark; Quirk, James J; Kiyanda, Charles B

2010-01-01

Non-ideal high explosives are typically porous, low-density materials with a low detonation velocity (3--5 km/s) and long detonation reaction zone ({approx} cms). As a result, the interaction of a non-ideal high explosive with an inert confiner can be markedly different than for a conventional high explosive. Issues arise, for example, with light stiff confiners where the confiner can drive the high explosive (HE) through a Prandtl-Meyer fan at the HE/confiner interface rather than the HE driving the confiner. For a non-ideal high explosive confined by a high sound speed inert such that the detonation velocity is lower than the inertmore » sound speed, the flow is subsonic and thus shockless in the confiner. In such cases, the standard detonation shock dynamics methodology, which requires a positive edge-angle be specified at the HE/confiner interface in order that the detonation shape be divergent, cannot be directly utilized. In order to study how detonation shock dynamics can be utilized in such cases, numerical simulations of the detonation of ammonium nitrate-fuel oil (ANFO) confined by aluminum 6061 are conducted.« less

High-Speed Friction-Stir Welding To Enable Aluminum Tailor-Welded Blanks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovanski, Yuri; Upadhyay, Piyush; Carsley, John

Current joining technologies for automotive aluminum alloys are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding has been traditionally applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translatemore » to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum welded components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability utilizing a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.« less

High-Lift Capability of Low Aspect Ratio Wings Utilizing Circulation Control and Upper Surface Blowing

DTIC Science & Technology

1980-07-01

span, ft (m) CD Drag coefficient, D/qS I CD Drag coefficient at zero lift CL Lift coefficient, L/qS CL Lift curve elope, aCL/aa I CL Maximum lift...recording on magnetic tape utilizing a Beckman 210 high-speed acquistion system. The wing-fuselage model was mounted in the test section such that...6, 7, and 8 show the tip sails have little impact on the zero or low-lift drag, but these j sails definitely influence the induced drag that is deve

Network-linked long-time recording high-speed video camera system

NASA Astrophysics Data System (ADS)

Kimura, Seiji; Tsuji, Masataka

2001-04-01

This paper describes a network-oriented, long-recording-time high-speed digital video camera system that utilizes an HDD (Hard Disk Drive) as a recording medium. Semiconductor memories (DRAM, etc.) are the most common image data recording media with existing high-speed digital video cameras. They are extensively used because of their advantage of high-speed writing and reading of picture data. The drawback is that their recording time is limited to only several seconds because the data amount is very large. A recording time of several seconds is sufficient for many applications. However, a much longer recording time is required in some applications where an exact prediction of trigger timing is hard to make. In the Late years, the recording density of the HDD has been dramatically improved, which has attracted more attention to its value as a long-recording-time medium. We conceived an idea that we would be able to build a compact system that makes possible a long time recording if the HDD can be used as a memory unit for high-speed digital image recording. However, the data rate of such a system, capable of recording 640 X 480 pixel resolution pictures at 500 frames per second (fps) with 8-bit grayscale is 153.6 Mbyte/sec., and is way beyond the writing speed of the commonly used HDD. So, we developed a dedicated image compression system and verified its capability to lower the data rate from the digital camera to match the HDD writing rate.

Results of design studies and wind tunnel tests of an advanced high lift system for an Energy Efficient Transport

NASA Technical Reports Server (NTRS)

Oliver, W. R.

1980-01-01

The development of an advanced technology high lift system for an energy efficient transport incorporating a high aspect ratio supercritical wing is described. This development is based on the results of trade studies to select the high lift system, analysis techniques utilized to design the high lift system, and results of a wind tunnel test program. The program included the first experimental low speed, high Reynolds number wind tunnel test for this class of aircraft. The experimental results include the effects on low speed aerodynamic characteristics of various leading and trailing edge devices, nacelles and pylons, aileron, spoilers, and Mach and Reynolds numbers. Results are discussed and compared with the experimental data and the various aerodynamic characteristics are estimated.

Numerical solution of the wave equation with variable wave speed on nonconforming domains by high-order difference potentials

NASA Astrophysics Data System (ADS)

Britt, S.; Tsynkov, S.; Turkel, E.

2018-02-01

We solve the wave equation with variable wave speed on nonconforming domains with fourth order accuracy in both space and time. This is accomplished using an implicit finite difference (FD) scheme for the wave equation and solving an elliptic (modified Helmholtz) equation at each time step with fourth order spatial accuracy by the method of difference potentials (MDP). High-order MDP utilizes compact FD schemes on regular structured grids to efficiently solve problems on nonconforming domains while maintaining the design convergence rate of the underlying FD scheme. Asymptotically, the computational complexity of high-order MDP scales the same as that for FD.

Offset Compound Gear Inline Two-Speed Drive

NASA Technical Reports Server (NTRS)

Stevens, Mark A. (Inventor); Handschuh, Robert F. (Inventor); Lewicki, David G. (Inventor)

2012-01-01

A two-speed transmission having an input shaft and an output shaft, the transmission being capable of transitioning between fixed ratios, the high-range ratio being direct 1:1 and the low-range ratio being about 2:1. The transmission is a simple lightweight, yet robust, configuration utilizing only two gear meshes, being comprised of an input gear, a cluster gear, and an output gear. The transmission is controlled with a clutch and a sprag and with the input and output shafts turning in the same direction.

Computational fluid mechanics utilizing the variational principle of modeling damping seals

NASA Technical Reports Server (NTRS)

Abernathy, J. M.

1986-01-01

A computational fluid dynamics code for application to traditional incompressible flow problems has been developed. The method is actually a slight compressibility approach which takes advantage of the bulk modulus and finite sound speed of all real fluids. The finite element numerical analog uses a dynamic differencing scheme based, in part, on a variational principle for computational fluid dynamics. The code was developed in order to study the feasibility of damping seals for high speed turbomachinery. Preliminary seal analyses have been performed.

Offset Compound Gear Inline Two-Speed Drive

NASA Technical Reports Server (NTRS)

Stevens, Mark A. (Inventor); Handschuh, Robert F. (Inventor); Lewicki, David G. (Inventor)

2014-01-01

A two-speed transmission having an input shaft and an output shaft, the transmission being capable of transitioning between fixed ratios, the high-range ratio being direct 1:1 and the low-range ratio being about 2:1. The transmission is a simple lightweight, yet robust, configuration utilizing only two gear meshes, being comprised of an input gear, a cluster gear, and an output gear. The transmission is controlled with a clutch and a sprag and with the input and output shafts turning in the same direction.

Scanning digital lithography providing high speed large area patterning with diffraction limited sub-micron resolution

NASA Astrophysics Data System (ADS)

Wen, Sy-Bor; Bhaskar, Arun; Zhang, Hongjie

2018-07-01

A scanning digital lithography system using computer controlled digital spatial light modulator, spatial filter, infinity correct optical microscope and high precision translation stage is proposed and examined. Through utilizing the spatial filter to limit orders of diffraction modes for light delivered from the spatial light modulator, we are able to achieve diffraction limited deep submicron spatial resolution with the scanning digital lithography system by using standard one inch level optical components with reasonable prices. Raster scanning of this scanning digital lithography system using a high speed high precision x-y translation stage and piezo mount to real time adjust the focal position of objective lens allows us to achieve large area sub-micron resolved patterning with high speed (compared with e-beam lithography). It is determined in this study that to achieve high quality stitching of lithography patterns with raster scanning, a high-resolution rotation stage will be required to ensure the x and y directions of the projected pattern are in the same x and y translation directions of the nanometer precision x-y translation stage.

Image restoration method based on Hilbert transform for full-field optical coherence tomography

NASA Astrophysics Data System (ADS)

Na, Jihoon; Choi, Woo June; Choi, Eun Seo; Ryu, Seon Young; Lee, Byeong Ha

2008-01-01

A full-field optical coherence tomography (FF-OCT) system utilizing a simple but novel image restoration method suitable for a high-speed system is demonstrated. An en-face image is retrieved from only two phase-shifted interference fringe images through using the mathematical Hilbert transform. With a thermal light source, a high-resolution FF-OCT system having axial and transverse resolutions of 1 and 2.2 μm, respectively, was implemented. The feasibility of the proposed scheme is confirmed by presenting the obtained en-face images of biological samples such as a piece of garlic and a gold beetle. The proposed method is robust to the error in the amount of the phase shift and does not leave residual fringes. The use of just two interference images and the strong immunity to phase errors provide great advantages in the imaging speed and the system design flexibility of a high-speed high-resolution FF-OCT system.

Process optimization of an auger pyrolyzer with heat carrier using response surface methodology.

PubMed

Brown, J N; Brown, R C

2012-01-01

A 1 kg/h auger reactor utilizing mechanical mixing of steel shot heat carrier was used to pyrolyze red oak wood biomass. Response surface methodology was employed using a circumscribed central composite design of experiments to optimize the system. Factors investigated were: heat carrier inlet temperature and mass flow rate, rotational speed of screws in the reactor, and volumetric flow rate of sweep gas. Conditions for maximum bio-oil and minimum char yields were high flow rate of sweep gas (3.5 standard L/min), high heat carrier temperature (∼600 °C), high auger speeds (63 RPM) and high heat carrier mass flow rates (18 kg/h). Regression models for bio-oil and char yields are described including identification of a novel interaction effect between heat carrier mass flow rate and auger speed. Results suggest that auger reactors, which are rarely described in literature, are well suited for bio-oil production. The reactor achieved liquid yields greater than 73 wt.%. Copyright © 2011 Elsevier Ltd. All rights reserved.

Mechanical pumps for superfluid helium transfer in space

NASA Technical Reports Server (NTRS)

Izenson, M. G.; Swift, W. L.

1988-01-01

Two alternate mechanical pump concepts have been identified for the transfer of superfluid helium in space. Both pumps provide flow at sufficient head and have operating characteristics suitable for the Space Infrared Telescope Facility (SIRTF) refill mission. One pump operates at a relatively low speed and utilizes mechanical roller bearings, while the other operates at a higher rotational speed using either electromagnetic or tilting pad gas-dynamic bearings. The use of gas bearings requires transfer of normal helium so that the gas pressure within the pump casing is high enough to operate the bearings. The operating characteristics of both pumps are predicted, the dimensions are estimated and major technology issues are identified. The major issues for each pump design are cavitation performance and bearing development. Roller bearings require quantified reliability for operation in space while electromagnetic bearings require basic development as well as a complex control system. The low speed pump has significantly poorer hydraulic efficiency than the high speed pump.

Current Technology for Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Scotti, Stephen J. (Compiler)

1992-01-01

Interest in thermal protection systems for high-speed vehicles is increasing because of the stringent requirements of such new projects as the Space Exploration Initiative, the National Aero-Space Plane, and the High-Speed Civil Transport, as well as the needs for improved capabilities in existing thermal protection systems in the Space Shuttle and in turbojet engines. This selection of 13 papers from NASA and industry summarizes the history and operational experience of thermal protection systems utilized in the national space program to date, and also covers recent development efforts in thermal insulation, refractory materials and coatings, actively cooled structures, and two-phase thermal control systems.

Analytical design of an advanced radial turbine. [automobile engines

NASA Technical Reports Server (NTRS)

Large, G. D.; Finger, D. G.; Linder, C. G.

1981-01-01

The aerodynamic and mechanical potential of a single stage ceramic radial inflow turbine was evaluated for a high temperature single stage automotive engine. The aerodynamic analysis utilizes a turbine system optimization technique to evaluate both radial and nonradial rotor blading. Selected turbine rotor configurations were evaluated mechanically with three dimensional finite element techniques. Results indicate that exceptionally high rotor tip speeds (2300 ft/sec) and performance potential are feasible with radial bladed rotors if the projected ceramic material properties are realized. Nonradial rotors reduced tip speed requirements (at constant turbine efficiency) but resulted in a lower cumulative probability of success due to higher blade and disk stresses.

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, III, Jerome J.; Halpern, Bret L.

1993-01-01

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures.

Stress fields in soft material induced by injection of highly-focused microjets

NASA Astrophysics Data System (ADS)

Miyazaki, Yuta; Endo, Nanami; Kawamoto, Sennosuke; Kiyama, Akihito; Tagawa, Yoshiyuki

2017-11-01

Needle-free drug injection systems using high-speed microjets are of great importance for medical innovations since they can solve problems of the conventional needle injection systems. However, the mechanical stress acting on the skin/muscle of patients during the penetration of liquid-drug microjets had not been clarified. In this study we investigate the stress caused by the penetration of microjets into soft materials, which is compared with the stress induced by the penetration of needles. In order to capture high-speed temporal evolution of the stress field inside the material, we utilized a high-speed polarized camera and gelatin that resembles human skin. Remarkably we find clear differences in the stress fields induced by microjets and needles. On one hand, high shear stress induced by the microjets is attenuated immediately after the injection, even though the liquid stays inside the soft material. On the other hand, high-shear stress induced by the needles stays and never decays unless the needles are entirely removed from the material. JSPS KAKENHI Grant Numbers 26709007 and 17H01246.

Adaptive Control of a Utility-Scale Wind Turbine Operating in Region 3

NASA Technical Reports Server (NTRS)

Frost, Susan A.; Balas, Mark J.; Wright, Alan D.

2009-01-01

Adaptive control techniques are well suited to nonlinear applications, such as wind turbines, which are difficult to accurately model and which have effects from poorly known operating environments. The turbulent and unpredictable conditions in which wind turbines operate create many challenges for their operation. In this paper, we design an adaptive collective pitch controller for a high-fidelity simulation of a utility scale, variable-speed horizontal axis wind turbine. The objective of the adaptive pitch controller in Region 3 is to regulate generator speed and reject step disturbances. The control objective is accomplished by collectively pitching the turbine blades. We use an extension of the Direct Model Reference Adaptive Control (DMRAC) approach to track a reference point and to reject persistent disturbances. The turbine simulation models the Controls Advanced Research Turbine (CART) of the National Renewable Energy Laboratory in Golden, Colorado. The CART is a utility-scale wind turbine which has a well-developed and extensively verified simulator. The adaptive collective pitch controller for Region 3 was compared in simulations with a bas celliansesical Proportional Integrator (PI) collective pitch controller. In the simulations, the adaptive pitch controller showed improved speed regulation in Region 3 when compared with the baseline PI pitch controller and it demonstrated robustness to modeling errors.

Determination of torque speed current characteristics of a brushless DC motor by utilizing back-EMF of non-energized phase

NASA Astrophysics Data System (ADS)

Jang, G. H.; Yeom, J. H.; Kim, M. G.

2007-03-01

This paper presents a method to determine the torque constant and the torque-speed-current characteristics of a brushless DC (BLDC) motor by utilizing back-EMF variation of nonenergized phase. It also develops a BLDC motor controller with a digital signal processor (DSP) to monitor its current, voltage and speed in real time. Torque-speed-current characteristics of a BLDC motor are determined by using the proposed method and the developed controller. They are compared with the torque-speed-current characteristics measured by dynamometer experimentally. This research shows that the proposed method is an effective method to determine the torque constant and the torque-speed-current characteristics of the BLDC motor without using dynamometer.

Evaluating the networking characteristics of the Cray XC-40 Intel Knights Landing-based Cori supercomputer at NERSC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doerfler, Douglas; Austin, Brian; Cook, Brandon

There are many potential issues associated with deploying the Intel Xeon Phi™ (code named Knights Landing [KNL]) manycore processor in a large-scale supercomputer. One in particular is the ability to fully utilize the high-speed communications network, given that the serial performance of a Xeon Phi TM core is a fraction of a Xeon®core. In this paper, we take a look at the trade-offs associated with allocating enough cores to fully utilize the Aries high-speed network versus cores dedicated to computation, e.g., the trade-off between MPI and OpenMP. In addition, we evaluate new features of Cray MPI in support of KNL,more » such as internode optimizations. We also evaluate one-sided programming models such as Unified Parallel C. We quantify the impact of the above trade-offs and features using a suite of National Energy Research Scientific Computing Center applications.« less

HIGH SPEED KERR CELL FRAMING CAMERA

DOEpatents

Goss, W.C.; Gilley, L.F.

1964-01-01

The present invention relates to a high speed camera utilizing a Kerr cell shutter and a novel optical delay system having no moving parts. The camera can selectively photograph at least 6 frames within 9 x 10/sup -8/ seconds during any such time interval of an occurring event. The invention utilizes particularly an optical system which views and transmits 6 images of an event to a multi-channeled optical delay relay system. The delay relay system has optical paths of successively increased length in whole multiples of the first channel optical path length, into which optical paths the 6 images are transmitted. The successively delayed images are accepted from the exit of the delay relay system by an optical image focusing means, which in turn directs the images into a Kerr cell shutter disposed to intercept the image paths. A camera is disposed to simultaneously view and record the 6 images during a single exposure of the Kerr cell shutter. (AEC)

Examples of variable speed limit applications : speed management workshop

DOT National Transportation Integrated Search

2000-01-09

VSL systems are a type of Intelligent Transportation System (ITS) that utilizes traffic : speed and volume detection, weather information, and road surface condition technology to determine appropriate speeds at which drivers should be traveling, giv...

Method and apparatus for water jet drilling of rock

DOEpatents

Summers, David A.; Mazurkiewicz, Marian; Bushnell, Dwight J.; Blaine, James

1978-01-01

Rock drilling method and apparatus utilizing high pressure water jets for drilling holes of relatively small diameter at speeds significantly greater than that attainable with existing drilling tools. Greatly increased drilling rates are attained due to jet nozzle geometry and speed of rotation. The jet nozzle design has two orifices, one pointing axially ahead in the direction of travel and the second inclined at an angle of approximately 30.degree. from the axis. The two orifices have diameters in the ratio of approximately 1:2. Liquid jet velocities in excess of 1,000 ft/sec are used, and the nozzle is rotated at speeds up to 1,000 rpm and higher.

14 CFR 23.51 - Takeoff speeds.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Takeoff speeds. 23.51 Section 23.51... speeds. (a) For normal, utility, and acrobatic category airplanes, rotation speed, VR, is the speed at... seaplanes and amphibians taking off from water, VR, may be any speed that is shown to be safe under all...

14 CFR 23.51 - Takeoff speeds.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Takeoff speeds. 23.51 Section 23.51... speeds. (a) For normal, utility, and acrobatic category airplanes, rotation speed, VR, is the speed at... seaplanes and amphibians taking off from water, VR, may be any speed that is shown to be safe under all...

An Incremental High-Utility Mining Algorithm with Transaction Insertion

PubMed Central

Gan, Wensheng; Zhang, Binbin

2015-01-01

Association-rule mining is commonly used to discover useful and meaningful patterns from a very large database. It only considers the occurrence frequencies of items to reveal the relationships among itemsets. Traditional association-rule mining is, however, not suitable in real-world applications since the purchased items from a customer may have various factors, such as profit or quantity. High-utility mining was designed to solve the limitations of association-rule mining by considering both the quantity and profit measures. Most algorithms of high-utility mining are designed to handle the static database. Fewer researches handle the dynamic high-utility mining with transaction insertion, thus requiring the computations of database rescan and combination explosion of pattern-growth mechanism. In this paper, an efficient incremental algorithm with transaction insertion is designed to reduce computations without candidate generation based on the utility-list structures. The enumeration tree and the relationships between 2-itemsets are also adopted in the proposed algorithm to speed up the computations. Several experiments are conducted to show the performance of the proposed algorithm in terms of runtime, memory consumption, and number of generated patterns. PMID:25811038

Rating of Dynamic Coefficient for Simple Beam Bridge Design on High-Speed Railways

NASA Astrophysics Data System (ADS)

Diachenko, Leonid; Benin, Andrey; Smirnov, Vladimir; Diachenko, Anastasia

2018-06-01

The aim of the work is to improve the methodology for the dynamic computation of simple beam spans during the impact of high-speed trains. Mathematical simulation utilizing numerical and analytical methods of structural mechanics is used in the research. The article analyses parameters of the effect of high-speed trains on simple beam spanning bridge structures and suggests a technique of determining of the dynamic index to the live load. Reliability of the proposed methodology is confirmed by results of numerical simulation of high-speed train passage over spans with different speeds. The proposed algorithm of dynamic computation is based on a connection between maximum acceleration of the span in the resonance mode of vibrations and the main factors of stress-strain state. The methodology allows determining maximum and also minimum values of the main efforts in the construction that makes possible to perform endurance tests. It is noted that dynamic additions for the components of the stress-strain state (bending moments, transverse force and vertical deflections) are different. This condition determines the necessity for differentiated approach to evaluation of dynamic coefficients performing design verification of I and II groups of limiting state. The practical importance: the methodology of determining the dynamic coefficients allows making dynamic calculation and determining the main efforts in split beam spans without numerical simulation and direct dynamic analysis that significantly reduces the labour costs for design.

Stirling engine with air working fluid

DOEpatents

Corey, John A.

1985-01-01

A Stirling engine capable of utilizing air as a working fluid which includes a compact heat exchange module which includes heating tube units, regenerator and cooler positioned about the combustion chamber. This arrangement has the purpose and effect of allowing the construction of an efficient, high-speed, high power-density engine without the use of difficult to seal light gases as working fluids.

Evaluation of Roadway Reallocation Projects: Analysis of Before-and-After Travel Speeds and Congestion Utilizing High-Resolution Bus Transit Data

DOT National Transportation Integrated Search

2017-11-01

The traditional process of identifying corridors for road diet improvements involves selecting potential corridors (mostly based on identifying fourlane roads) and conducting a traffic impact analysis of proposed changes on a selected roadway before ...

Tunable electro-optic filter stack

DOEpatents

Fontecchio, Adam K.; Shriyan, Sameet K.; Bellingham, Alyssa

2017-09-05

A holographic polymer dispersed liquid crystal (HPDLC) tunable filter exhibits switching times of no more than 20 microseconds. The HPDLC tunable filter can be utilized in a variety of applications. An HPDLC tunable filter stack can be utilized in a hyperspectral imaging system capable of spectrally multiplexing hyperspectral imaging data acquired while the hyperspectral imaging system is airborne. HPDLC tunable filter stacks can be utilized in high speed switchable optical shielding systems, for example as a coating for a visor or an aircraft canopy. These HPDLC tunable filter stacks can be fabricated using a spin coating apparatus and associated fabrication methods.

Nano- and micro-electromechanical switch dynamics

NASA Astrophysics Data System (ADS)

Pulskamp, Jeffrey S.; Proie, Robert M.; Polcawich, Ronald G.

2013-01-01

This paper reports theoretical analysis and experimental results on the dynamics of piezoelectric MEMS mechanical logic relays. The multiple degree of freedom analytical model, based on modal decomposition, utilizes modal parameters obtained from finite element analysis and an analytical model of piezoelectric actuation. The model accounts for exact device geometry, damping, drive waveform variables, and high electric field piezoelectric nonlinearity. The piezoelectrically excited modal force is calculated directly and provides insight into design optimization for switching speed. The model accurately predicts the propagation delay dependence on actuation voltage of mechanically distinct relay designs. The model explains the observed discrepancies in switching speed of these devices relative to single degree of freedom switching speed models and suggests the strong potential for improved switching speed performance in relays designed for mechanical logic and RF circuits through the exploitation of higher order vibrational modes.

Quasi-Uniform High Speed Foam Crush Testing Using a Guided Drop Mass Impact

NASA Technical Reports Server (NTRS)

Jones, Lisa E. (Technical Monitor); Kellas, Sotiris

2004-01-01

A relatively simple method for measuring the dynamic crush response of foam materials at various loading rates is described. The method utilizes a drop mass impact configuration with mass and impact velocity selected such that the crush speed remains approximately uniform during the entire sample crushing event. Instrumentation, data acquisition, and data processing techniques are presented, and limitations of the test method are discussed. The objective of the test method is to produce input data for dynamic finite element modeling involving crash and energy absorption characteristics of foam materials.

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, J.J. III; Halpern, B.L.

1993-10-26

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures. 5 figures.

Development of an Actuator for Flow Control Utilizing Detonation

NASA Technical Reports Server (NTRS)

Lonneman, Patrick J.; Cutler, Andrew D.

2004-01-01

Active flow control devices including mass injection systems and zero-net-mass flux actuators (synthetic jets) have been employed to delay flow separation. These devices are capable of interacting with low-speed, subsonic flows, but situations exist where a stronger crossflow interaction is needed. Small actuators that utilize detonation of premixed fuel and oxidizer should be capable of producing supersonic exit jet velocities. An actuator producing exit velocities of this magnitude should provide a more significant interaction with transonic and supersonic crossflows. This concept would be applicable to airfoils on high-speed aircraft as well as inlet and diffuser flow control. The present work consists of the development of a detonation actuator capable of producing a detonation in a single shot (one cycle). Multiple actuator configurations, initial fill pressures, oxidizers, equivalence ratios, ignition energies, and the addition of a turbulence generating device were considered experimentally and computationally. It was found that increased initial fill pressures and the addition of a turbulence generator aided in the detonation process. The actuators successfully produced Chapman-Jouguet detonations and wave speeds on the order of 3000 m/s.

Remote Transmission at High Speed

NASA Technical Reports Server (NTRS)

2003-01-01

Omni and NASA Test Operations at Stennis entered a Dual-Use Agreement to develop the FOTR-125, a 125 megabit-per-second fiber-optic transceiver that allows accurate digital recordings over a great distance. The transceiver s fiber-optic link can be as long as 25 kilometers. This makes it much longer than the standard coaxial link, which can be no longer than 50 meters.The FOTR-125 utilizes laser diode transmitter modules and integrated receivers for the optical interface. Two transmitters and two receivers are employed at each end of the link with automatic or manual switchover to maximize the reliability of the communications link. NASA uses the transceiver in Stennis High-Speed Data Acquisition System (HSDAS). The HSDAS consists of several identical systems installed on the Center s test stands to process all high-speed data related to its propulsion test programs. These transceivers allow the recorder and HSDAS controls to be located in the Test Control Center in a remote location while the digitizer is located on the test stand.

Quantitative Image Analysis Techniques with High-Speed Schlieren Photography

NASA Technical Reports Server (NTRS)

Pollard, Victoria J.; Herron, Andrew J.

2017-01-01

Optical flow visualization techniques such as schlieren and shadowgraph photography are essential to understanding fluid flow when interpreting acquired wind tunnel test data. Output of the standard implementations of these visualization techniques in test facilities are often limited only to qualitative interpretation of the resulting images. Although various quantitative optical techniques have been developed, these techniques often require special equipment or are focused on obtaining very precise and accurate data about the visualized flow. These systems are not practical in small, production wind tunnel test facilities. However, high-speed photography capability has become a common upgrade to many test facilities in order to better capture images of unsteady flow phenomena such as oscillating shocks and flow separation. This paper describes novel techniques utilized by the authors to analyze captured high-speed schlieren and shadowgraph imagery from wind tunnel testing for quantification of observed unsteady flow frequency content. Such techniques have applications in parametric geometry studies and in small facilities where more specialized equipment may not be available.

Pressure Pulsation in a High Head Francis Turbine Operating at Variable Speed

NASA Astrophysics Data System (ADS)

Sannes, D. B.; Iliev, I.; Agnalt, E.; Dahlhaug, O. G.

2018-06-01

This paper presents the preliminary work of the master thesis of the author, written at the Norwegian University of Science and Technology. Today, many Francis turbines experience formations of cracks in the runner due to pressure pulsations. This can eventually cause failure. One way to reduce this effect is to change the operation point of the turbine, by utilizing variable speed technology. This work presents the results from measurements of the Francis turbine at the Waterpower Laboratory at NTNU. Measurements of pressure pulsations and efficiency were done for the whole operating range of a high head Francis model turbine. The results will be presented in a similar diagram as the Hill Chart, but instead of constant efficiency curves there will be curves of constant peak-peak values. This way, it is possible to find an optimal operation point for the same power production, were the pressure pulsations are at its lowest. Six points were chosen for further analysis to instigate the effect of changing the speed by ±50 rpm. The analysis shows best results for operation below BEP when the speed was reduced. The change in speed also introduced the possibility to have other frequencies in the system. It is therefore important avoid runner speeds that can cause resonance in the system.

Towards roll-to-roll manufacturing of polymer photonic devices

NASA Astrophysics Data System (ADS)

Subbaraman, Harish; Lin, Xiaohui; Ling, Tao; Guo, L. Jay; Chen, Ray T.

2014-03-01

Traditionally, polymer photonic devices are fabricated using clean-room processes such as photolithography, e-beam lithography, reactive ion etching (RIE) and lift-off methods etc, which leads to long fabrication time, low throughput and high cost. We have utilized a novel process for fabricating polymer photonic devices using a combination of imprinting and ink jet printing methods, which provides high throughput on a variety of rigid and flexible substrates with low cost. We discuss the manufacturing challenges that need to be overcome in order to realize true implementation of roll-to-roll manufacturing of flexible polymer photonic systems. Several metrology and instrumentation challenges involved such as availability of particulate-free high quality substrate, development and implementation of high-speed in-line and off-line inspection and diagnostic tools with adaptive control for patterned and unpatterned material films, development of reliable hardware, etc need to be addressed and overcome in order to realize a successful manufacturing process. Due to extreme resolution requirements compared to print media, the burden of software and hardware tools on the throughput also needs to be carefully determined. Moreover, the effect of web wander and variations in web speed need to accurately be determined in the design of the system hardware and software. In this paper, we show the realization of solutions for few challenges, and utilizing these solutions for developing a high-rate R2R dual stage ink-jet printer that can provide alignment accuracy of <10μm at a web speed of 5m/min. The development of a roll-to-roll manufacturing system for polymer photonic systems opens limitless possibilities for the deployment of high performance components in a variety of applications including communication, sensing, medicine, agriculture, energy, lighting etc.

Efficiency of laser beam utilization in gas laser cutting of materials

NASA Astrophysics Data System (ADS)

Galushkin, M. G.; Grishaev, R. V.

2018-02-01

Relying on the condition of dynamic matching of the process parameters in gas laser cutting, the dependence of the beam utilization factor on the cutting speed and the beam power has been determined. An energy balance equation has been derived for a wide range of cutting speed values.

Detonation Propagation in Slabs and Axisymmetric Rate Sticks

NASA Astrophysics Data System (ADS)

Romick, Christopher; Aslam, Tariq

Insensitive high explosives (IHE) have many benefits; however, these IHEs exhibit longer reaction zones than more conventional high explosives (HE). This makes IHEs less ideal explosives and more susceptible to edge effects as well as other performance degradation issues. Thus, there is a resulting reduction in the detonation speed within the explosive. Many HE computational models, e. g. WSD, SURF, CREST, have shock-dependent reaction rates. This dependency places a high value on having an accurate shock speed. In the common practice of shock-capturing, there is ambiguity in the shock-state due to smoothing of the shock-front. Moreover, obtaining an accurate shock speed with shock-capturing becomes prohibitively computationally expensive in multiple dimensions. The use of shock-fitting removes the ambiguity of the shock-state as it is one of the boundaries. As such, the required resolution for a given error in the detonation speed is less than with shock-capturing. This allows for further insight into performance degradation. A two-dimensional shock-fitting scheme has been developed for unconfined slabs and rate sticks of HE. The HE modeling is accomplished by Euler equations utilizing several models with single-step irreversible kinetics in slab and rate stick geometries. Department of Energy - LANL.

An improved AE detection method of rail defect based on multi-level ANC with VSS-LMS

NASA Astrophysics Data System (ADS)

Zhang, Xin; Cui, Yiming; Wang, Yan; Sun, Mingjian; Hu, Hengshan

2018-01-01

In order to ensure the safety and reliability of railway system, Acoustic Emission (AE) method is employed to investigate rail defect detection. However, little attention has been paid to the defect detection at high speed, especially for noise interference suppression. Based on AE technology, this paper presents an improved rail defect detection method by multi-level ANC with VSS-LMS. Multi-level noise cancellation based on SANC and ANC is utilized to eliminate complex noises at high speed, and tongue-shaped curve with index adjustment factor is proposed to enhance the performance of variable step-size algorithm. Defect signals and reference signals are acquired by the rail-wheel test rig. The features of noise signals and defect signals are analyzed for effective detection. The effectiveness of the proposed method is demonstrated by comparing with the previous study, and different filter lengths are investigated to obtain a better noise suppression performance. Meanwhile, the detection ability of the proposed method is verified at the top speed of the test rig. The results clearly illustrate that the proposed method is effective in detecting rail defects at high speed, especially for noise interference suppression.

A methodology for achieving high-speed rates for artificial conductance injection in electrically excitable biological cells.

PubMed

Butera, R J; Wilson, C G; Delnegro, C A; Smith, J C

2001-12-01

We present a novel approach to implementing the dynamic-clamp protocol (Sharp et al., 1993), commonly used in neurophysiology and cardiac electrophysiology experiments. Our approach is based on real-time extensions to the Linux operating system. Conventional PC-based approaches have typically utilized single-cycle computational rates of 10 kHz or slower. In thispaper, we demonstrate reliable cycle-to-cycle rates as fast as 50 kHz. Our system, which we call model reference current injection (MRCI); pronounced merci is also capable of episodic logging of internal state variables and interactive manipulation of model parameters. The limiting factor in achieving high speeds was not processor speed or model complexity, but cycle jitter inherent in the CPU/motherboard performance. We demonstrate these high speeds and flexibility with two examples: 1) adding action-potential ionic currents to a mammalian neuron under whole-cell patch-clamp and 2) altering a cell's intrinsic dynamics via MRCI while simultaneously coupling it via artificial synapses to an internal computational model cell. These higher rates greatly extend the applicability of this technique to the study of fast electrophysiological currents such fast a currents and fast excitatory/inhibitory synapses.

Determinants of the reliability of ultrasound tomography sound speed estimates as a surrogate for volumetric breast density

PubMed Central

Khodr, Zeina G.; Sak, Mark A.; Pfeiffer, Ruth M.; Duric, Nebojsa; Littrup, Peter; Bey-Knight, Lisa; Ali, Haythem; Vallieres, Patricia; Sherman, Mark E.; Gierach, Gretchen L.

2015-01-01

Purpose: High breast density, as measured by mammography, is associated with increased breast cancer risk, but standard methods of assessment have limitations including 2D representation of breast tissue, distortion due to breast compression, and use of ionizing radiation. Ultrasound tomography (UST) is a novel imaging method that averts these limitations and uses sound speed measures rather than x-ray imaging to estimate breast density. The authors evaluated the reproducibility of measures of speed of sound and changes in this parameter using UST. Methods: One experienced and five newly trained raters measured sound speed in serial UST scans for 22 women (two scans per person) to assess inter-rater reliability. Intrarater reliability was assessed for four raters. A random effects model was used to calculate the percent variation in sound speed and change in sound speed attributable to subject, scan, rater, and repeat reads. The authors estimated the intraclass correlation coefficients (ICCs) for these measures based on data from the authors’ experienced rater. Results: Median (range) time between baseline and follow-up UST scans was five (1–13) months. Contributions of factors to sound speed variance were differences between subjects (86.0%), baseline versus follow-up scans (7.5%), inter-rater evaluations (1.1%), and intrarater reproducibility (∼0%). When evaluating change in sound speed between scans, 2.7% and ∼0% of variation were attributed to inter- and intrarater variation, respectively. For the experienced rater’s repeat reads, agreement for sound speed was excellent (ICC = 93.4%) and for change in sound speed substantial (ICC = 70.4%), indicating very good reproducibility of these measures. Conclusions: UST provided highly reproducible sound speed measurements, which reflect breast density, suggesting that UST has utility in sensitively assessing change in density. PMID:26429241

Determinants of the reliability of ultrasound tomography sound speed estimates as a surrogate for volumetric breast density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodr, Zeina G.; Pfeiffer, Ruth M.; Gierach, Gretchen L., E-mail: GierachG@mail.nih.gov

Purpose: High breast density, as measured by mammography, is associated with increased breast cancer risk, but standard methods of assessment have limitations including 2D representation of breast tissue, distortion due to breast compression, and use of ionizing radiation. Ultrasound tomography (UST) is a novel imaging method that averts these limitations and uses sound speed measures rather than x-ray imaging to estimate breast density. The authors evaluated the reproducibility of measures of speed of sound and changes in this parameter using UST. Methods: One experienced and five newly trained raters measured sound speed in serial UST scans for 22 women (twomore » scans per person) to assess inter-rater reliability. Intrarater reliability was assessed for four raters. A random effects model was used to calculate the percent variation in sound speed and change in sound speed attributable to subject, scan, rater, and repeat reads. The authors estimated the intraclass correlation coefficients (ICCs) for these measures based on data from the authors’ experienced rater. Results: Median (range) time between baseline and follow-up UST scans was five (1–13) months. Contributions of factors to sound speed variance were differences between subjects (86.0%), baseline versus follow-up scans (7.5%), inter-rater evaluations (1.1%), and intrarater reproducibility (∼0%). When evaluating change in sound speed between scans, 2.7% and ∼0% of variation were attributed to inter- and intrarater variation, respectively. For the experienced rater’s repeat reads, agreement for sound speed was excellent (ICC = 93.4%) and for change in sound speed substantial (ICC = 70.4%), indicating very good reproducibility of these measures. Conclusions: UST provided highly reproducible sound speed measurements, which reflect breast density, suggesting that UST has utility in sensitively assessing change in density.« less

The finite element method in low speed aerodynamics

NASA Technical Reports Server (NTRS)

Baker, A. J.; Manhardt, P. D.

1975-01-01

The finite element procedure is shown to be of significant impact in design of the 'computational wind tunnel' for low speed aerodynamics. The uniformity of the mathematical differential equation description, for viscous and/or inviscid, multi-dimensional subsonic flows about practical aerodynamic system configurations, is utilized to establish the general form of the finite element algorithm. Numerical results for inviscid flow analysis, as well as viscous boundary layer, parabolic, and full Navier Stokes flow descriptions verify the capabilities and overall versatility of the fundamental algorithm for aerodynamics. The proven mathematical basis, coupled with the distinct user-orientation features of the computer program embodiment, indicate near-term evolution of a highly useful analytical design tool to support computational configuration studies in low speed aerodynamics.

The MOD-OA 200 kilowatt wind turbine generator design and analysis report

NASA Astrophysics Data System (ADS)

Andersen, T. S.; Bodenschatz, C. A.; Eggers, A. G.; Hughes, P. S.; Lampe, R. F.; Lipner, M. H.; Schornhorst, J. R.

1980-08-01

The project requirements, approach, system description, design requirements, design, analysis, system tests, installation safety considerations, failure modes and effects analysis, data acquisition, and initial performance for the MOD-OA 200 kw wind turbine generator are discussed. The components, the rotor, driven train, nacelle equipment, yaw drive mechanism and brake, tower, foundation, electrical system, and control systems are presented. The rotor includes the blades, hub and pitch change mechanism. The drive train includes the low speed shaft, speed increaser, high speed shaft, and rotor brake. The electrical system includes the generator, switchgear, transformer, and utility connection. The control systems are the blade pitch, yaw, and generator control, and the safety system. Manual, automatic, and remote control and Dynamic loads and fatigue are analyzed.

The MOD-OA 200 kilowatt wind turbine generator design and analysis report

NASA Technical Reports Server (NTRS)

Andersen, T. S.; Bodenschatz, C. A.; Eggers, A. G.; Hughes, P. S.; Lampe, R. F.; Lipner, M. H.; Schornhorst, J. R.

1980-01-01

The project requirements, approach, system description, design requirements, design, analysis, system tests, installation safety considerations, failure modes and effects analysis, data acquisition, and initial performance for the MOD-OA 200 kw wind turbine generator are discussed. The components, the rotor, driven train, nacelle equipment, yaw drive mechanism and brake, tower, foundation, electrical system, and control systems are presented. The rotor includes the blades, hub and pitch change mechanism. The drive train includes the low speed shaft, speed increaser, high speed shaft, and rotor brake. The electrical system includes the generator, switchgear, transformer, and utility connection. The control systems are the blade pitch, yaw, and generator control, and the safety system. Manual, automatic, and remote control and Dynamic loads and fatigue are analyzed.

Design project: LONGBOW supersonic interceptor

NASA Technical Reports Server (NTRS)

Stoney, Robert; Baker, Matt; Capstaff, Joseph G.; Dishman, Robert; Fick, Gregory; Frick, Stephen N.; Kelly, Mark

1993-01-01

A recent white paper entitled 'From the Sea' has spotlighted the need for Naval Aviation to provide overland support to joint operations. The base for this support, the Aircraft Carrier (CVN), will frequently be unable to operate within close range of the battleground because of littoral land-based air and subsurface threats. A high speed, long range, carrier capable aircraft would allow the CVN to provide timely support to distant battleground operations. Such an aircraft, operating as a Deck-Launched Interceptor (DLI), would also be an excellent counter to Next Generation Russian Naval Aviation (NGRNA) threats consisting of supersonic bombers, such as the Backfire, equipped with the next generation of high-speed, long-range missiles. Additionally, it would serve as an excellent high speed Reconnaissance airplane, capable of providing Battle Force commanders with timely, accurate pre-mission targeting information and post-mission Bomb Damage Assessment (BDA). Recent advances in computational hypersonic airflow modeling has produced a method of defining aircraft shapes that fit a conical shock flow model to maximize the efficiency of the vehicle. This 'Waverider' concept provides one means of achieving long ranges at high speeds. A Request for Proposal (RFP) was issued by Professor Conrad Newberry that contained design requirements for an aircraft to accomplish the above stated missions, utilizing Waverider technology.

Mechanical design problems associated with turbopump fluid film bearings

NASA Technical Reports Server (NTRS)

Evces, Charles R.

1990-01-01

Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller contact bearings for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make bearing wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, bearings must currently be replaced after 2 missions. One solution to the bearing wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film bearings in lieu of continuous contact bearings. Hydrostatic, hydrodynamic, and damping seal bearings are all replacement candidates for contact bearings in rocket engine high speed turbomachinery. These three types of fluid film bearings have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, bearing wear inspection and measurement, and bearing fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) bearing, but the results are pertinent to high-speed cryogenic turbomachinery in general.

High speed turbulent reacting flows: DNS and LES

NASA Technical Reports Server (NTRS)

Givi, Peyman

1990-01-01

Work on understanding the mechanisms of mixing and reaction in high speed turbulent reacting flows was continued. Efforts, in particular, were concentrated on taking advantage of modern computational methods to simulate high speed turbulent flows. In doing so, two methodologies were used: large eddy simulations (LES) and direct numerical simulations (DNS). In the work related with LES the objective is to study the behavior of the probability density functions (pdfs) of scalar properties within the subgrid in reacting turbulent flows. The data base obtained by DNS for a detailed study of the pdf characteristics within the subgrid was used. Simulations are performed for flows under various initializations to include the effects of compressibility on mixing and chemical reactions. In the work related with DNS, a two-dimensional temporally developing high speed mixing layer under the influence of a second-order non-equilibrium chemical reaction of the type A + B yields products + heat was considered. Simulations were performed with different magnitudes of the convective Mach numbers and with different chemical kinetic parameters for the purpose of examining the isolated effects of the compressibility and the heat released by the chemical reactions on the structure of the layer. A full compressible code was developed and utilized, so that the coupling between mixing and chemical reactions is captured in a realistic manner.

Ultrafast Silicon-based Modulators using Optical Switching of Vanadium Dioxide

DTIC Science & Technology

2014-12-04

demonstrated by using photothermal heating to induce the VO2 semiconductor-to- metal phase transition and modulate the transmitted optical signal...speeds. By utilizing the sub-picosecond semiconductor-to- metal transition (SMT) in VO2 as the active switching mechanism that enables direct... metallic phases. The steep slope, high contrast, and relatively narrow hysteresis exhibited by these reflectivity measurements indicate the high quality

High-Speed Systolic Array Testbed.

DTIC Science & Technology

1987-10-01

applications since the concept was introduced by H.T. Kung In 1978. This highly parallel architecture of nearet neighbor data communciation and...must be addressed. For instance, should bit-serial or bit parallei computation be utilized. Does the dynamic range of the candidate applications or...numericai stability of the algorithms used require computations In fixed point and Integer format or the architecturally more complex and slower floating

Large area high-speed metrology SPM system.

PubMed

Klapetek, P; Valtr, M; Picco, L; Payton, O D; Martinek, J; Yacoot, A; Miles, M

2015-02-13

We present a large area high-speed measuring system capable of rapidly generating nanometre resolution scanning probe microscopy data over mm(2) regions. The system combines a slow moving but accurate large area XYZ scanner with a very fast but less accurate small area XY scanner. This arrangement enables very large areas to be scanned by stitching together the small, rapidly acquired, images from the fast XY scanner while simultaneously moving the slow XYZ scanner across the region of interest. In order to successfully merge the image sequences together two software approaches for calibrating the data from the fast scanner are described. The first utilizes the low uncertainty interferometric sensors of the XYZ scanner while the second implements a genetic algorithm with multiple parameter fitting during the data merging step of the image stitching process. The basic uncertainty components related to these high-speed measurements are also discussed. Both techniques are shown to successfully enable high-resolution, large area images to be generated at least an order of magnitude faster than with a conventional atomic force microscope.

Large area high-speed metrology SPM system

NASA Astrophysics Data System (ADS)

Klapetek, P.; Valtr, M.; Picco, L.; Payton, O. D.; Martinek, J.; Yacoot, A.; Miles, M.

2015-02-01

We present a large area high-speed measuring system capable of rapidly generating nanometre resolution scanning probe microscopy data over mm2 regions. The system combines a slow moving but accurate large area XYZ scanner with a very fast but less accurate small area XY scanner. This arrangement enables very large areas to be scanned by stitching together the small, rapidly acquired, images from the fast XY scanner while simultaneously moving the slow XYZ scanner across the region of interest. In order to successfully merge the image sequences together two software approaches for calibrating the data from the fast scanner are described. The first utilizes the low uncertainty interferometric sensors of the XYZ scanner while the second implements a genetic algorithm with multiple parameter fitting during the data merging step of the image stitching process. The basic uncertainty components related to these high-speed measurements are also discussed. Both techniques are shown to successfully enable high-resolution, large area images to be generated at least an order of magnitude faster than with a conventional atomic force microscope.

Validation of CFD simulation of recoilless EOD water cannon by firing experiments with high speed camera

NASA Astrophysics Data System (ADS)

Chantrasmi, Tonkid; Hongthong, Premsiri; Kongkaniti, Manop

2018-01-01

Water cannon used by Explosive Ordnance Disposal (EOD) were designed to propel a burst of water jet moving at high speed to target and disrupt an improvised explosive device (IED). The cannon could be mounted on a remotely controlled robot, so it is highly desirable for the cannon to be recoilless in order not to damage the robot after firing. In the previous work, a nonconventional design of the water cannon was conceived. The recoil was greatly reduced by backward sprays of water through a ring of slotted holes around the muzzle. This minimizes the need to manufacture new parts by utilizing all off-the-shelf components except the tailor-made muzzle. The design was then investigated numerically by a series of Computational Fluid Dynamics (CFD) simulations. In this work, high speed camera was employed in firing experiments to capture the motion of the water jet and the backward sprays. It was found that the experimental data agreed well with the simulation results in term of averaged exit velocities.

Proposed Space Flight Experiment Hardware

NASA Technical Reports Server (NTRS)

2003-01-01

The primary thrust for this plan is to develop design tools and fundamental understanding that are timely and consistent with the goal of the various exploration initiatives. The plan will utilize ISS facilities, such as the Fluids Integrated Rack (FIR) and the Microgravity Science Glovebox (MSG). A preliminary flow schematic of Two-Phase Flow Facility (T(phi)FFy) which would utilize FIR is shown in Figure 3. MSG can be utilized to use the Boiling eXperiment Facility (BXF) and Contact Line Dynamics Experiment (CLiDE) Facility. The T(phi)FFy system would have multiple test sections whereby different configurations of heat exchangers could be used to study boiling and condensation phenomena. The test sections would be instrumented for pressure drop, void fraction, heat fluxes, temperatures, high-speed imaging and other diagnostics. Besides a high-speed data acquisition system with a large data storage capability, telemetry could be used to update control and test parameters and download limited amounts of data. In addition, there would be multiple accumulators that could be used to investigate system stability and fluid management issues. The system could accommodate adiabatic tests through either the space station nitrogen supply or have an experiment-specific compressor to pressurize a sufficient amount of air or other non-condensable gas for reuse as the supply bottle is depleted.

Ultrafast dark-field surface inspection with hybrid-dispersion laser scanning

NASA Astrophysics Data System (ADS)

Yazaki, Akio; Kim, Chanju; Chan, Jacky; Mahjoubfar, Ata; Goda, Keisuke; Watanabe, Masahiro; Jalali, Bahram

2014-06-01

High-speed surface inspection plays an important role in industrial manufacturing, safety monitoring, and quality control. It is desirable to go beyond the speed limitation of current technologies for reducing manufacturing costs and opening a new window onto a class of applications that require high-throughput sensing. Here, we report a high-speed dark-field surface inspector for detection of micrometer-sized surface defects that can travel at a record high speed as high as a few kilometers per second. This method is based on a modified time-stretch microscope that illuminates temporally and spatially dispersed laser pulses on the surface of a fast-moving object and detects scattered light from defects on the surface with a sensitive photodetector in a dark-field configuration. The inspector's ability to perform ultrafast dark-field surface inspection enables real-time identification of difficult-to-detect features on weakly reflecting surfaces and hence renders the method much more practical than in the previously demonstrated bright-field configuration. Consequently, our inspector provides nearly 1000 times higher scanning speed than conventional inspectors. To show our method's broad utility, we demonstrate real-time inspection of the surface of various objects (a non-reflective black film, transparent flexible film, and reflective hard disk) for detection of 10 μm or smaller defects on a moving target at 20 m/s within a scan width of 25 mm at a scan rate of 90.9 MHz. Our method holds promise for improving the cost and performance of organic light-emitting diode displays for next-generation smart phones, lithium-ion batteries for green electronics, and high-efficiency solar cells.

Real-time speckle variance swept-source optical coherence tomography using a graphics processing unit.

PubMed

Lee, Kenneth K C; Mariampillai, Adrian; Yu, Joe X Z; Cadotte, David W; Wilson, Brian C; Standish, Beau A; Yang, Victor X D

2012-07-01

Advances in swept source laser technology continues to increase the imaging speed of swept-source optical coherence tomography (SS-OCT) systems. These fast imaging speeds are ideal for microvascular detection schemes, such as speckle variance (SV), where interframe motion can cause severe imaging artifacts and loss of vascular contrast. However, full utilization of the laser scan speed has been hindered by the computationally intensive signal processing required by SS-OCT and SV calculations. Using a commercial graphics processing unit that has been optimized for parallel data processing, we report a complete high-speed SS-OCT platform capable of real-time data acquisition, processing, display, and saving at 108,000 lines per second. Subpixel image registration of structural images was performed in real-time prior to SV calculations in order to reduce decorrelation from stationary structures induced by the bulk tissue motion. The viability of the system was successfully demonstrated in a high bulk tissue motion scenario of human fingernail root imaging where SV images (512 × 512 pixels, n = 4) were displayed at 54 frames per second.

Effect of Wind Speed and Relative Humidity on Atmospheric Dust Concentrations in Semi-Arid Climates

PubMed Central

Csavina, Janae; Field, Jason; Félix, Omar; Corral-Avitia, Alba Y.; Sáez, A. Eduardo; Betterton, Eric A.

2014-01-01

Atmospheric particulate have deleterious impacts on human health. Predicting dust and aerosol emission and transport would be helpful to reduce harmful impacts but, despite numerous studies, prediction of dust events and contaminant transport in dust remains challenging. In this work, we show that relative humidity and wind speed are both determinants in atmospheric dust concentration. Observations of atmospheric dust concentrations in Green Valley, AZ, USA, and Juárez, Chihuahua, México, show that PM10 concentrations are not directly correlated with wind speed or relative humidity separately. However, selecting the data for high wind speeds (> 4 m/s at 10 m elevation), a definite trend is observed between dust concentration and relative humidity: dust concentration increases with relative humidity, reaching a maximum around 25% and it subsequently decreases with relative humidity. Models for dust storm forecasting may be improved by utilizing atmospheric humidity and wind speed as main drivers for dust generation and transport. PMID:24769193

77 FR 37733 - Technical Standard Order (TSO)-C68a, Airborne Automatic Dead Reckoning Computer Equipment...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-22

..., Airborne Automatic Dead Reckoning Computer Equipment Utilizing Aircraft Heading and Doppler Ground Speed.... ACTION: Notice of intent to cancel Technical Standard Order (TSO)-C68a, Airborne automatic dead reckoning... dead reckoning computer equipment utilizing aircraft heading and Doppler ground speed and drift angle...

Effect of lead-aircraft ground-speed on self-spacing performance using a cockpit display of traffic information

NASA Technical Reports Server (NTRS)

Kelly, J. R.

1983-01-01

A simulator investigation was conducted to determine the effect of the lead-aircraft ground-speed quantization level on self-spacing performance using a Cockpit Display of Traffic Information (CDTI). The study utilized a simulator employing cathode-ray tubes for the primary flight and navigation displays and highly augmented flight control modes. The pilot's task was to follow, and self-space on, a lead aircraft which was performing an idle-thrust profile descent to an instrument landing system (ILS) approach and landing. The spacing requirement was specified in terms of both a minimum distance and a time interval. The results indicate that the ground-speed quantization level, lead-aircraft scenario, and pilot technique had a significant effect on self-spacing performance. However, the ground-speed quantization level only had a significant effect on the performance when the lead aircraft flew a fast final approach.

A nonlinear dynamics approach for incorporating wind-speed patterns into wind-power project evaluation.

PubMed

Huffaker, Ray; Bittelli, Marco

2015-01-01

Wind-energy production may be expanded beyond regions with high-average wind speeds (such as the Midwest U.S.A.) to sites with lower-average speeds (such as the Southeast U.S.A.) by locating favorable regional matches between natural wind-speed and energy-demand patterns. A critical component of wind-power evaluation is to incorporate wind-speed dynamics reflecting documented diurnal and seasonal behavioral patterns. Conventional probabilistic approaches remove patterns from wind-speed data. These patterns must be restored synthetically before they can be matched with energy-demand patterns. How to accurately restore wind-speed patterns is a vexing problem spurring an expanding line of papers. We propose a paradigm shift in wind power evaluation that employs signal-detection and nonlinear-dynamics techniques to empirically diagnose whether synthetic pattern restoration can be avoided altogether. If the complex behavior of observed wind-speed records is due to nonlinear, low-dimensional, and deterministic system dynamics, then nonlinear dynamics techniques can reconstruct wind-speed dynamics from observed wind-speed data without recourse to conventional probabilistic approaches. In the first study of its kind, we test a nonlinear dynamics approach in an application to Sugarland Wind-the first utility-scale wind project proposed in Florida, USA. We find empirical evidence of a low-dimensional and nonlinear wind-speed attractor characterized by strong temporal patterns that match up well with regular daily and seasonal electricity demand patterns.

European shags optimize their flight behavior according to wind conditions.

PubMed

Kogure, Yukihisa; Sato, Katsufumi; Watanuki, Yutaka; Wanless, Sarah; Daunt, Francis

2016-02-01

Aerodynamics results in two characteristic speeds of flying birds: the minimum power speed and the maximum range speed. The minimum power speed requires the lowest rate of energy expenditure per unit time to stay airborne and the maximum range speed maximizes air distance traveled per unit of energy consumed. Therefore, if birds aim to minimize the cost of transport under a range of wind conditions, they are predicted to fly at the maximum range speed. Furthermore, take-off is predicted to be strongly affected by wind speed and direction. To investigate the effect of wind conditions on take-off and cruising flight behavior, we equipped 14 European shags Phalacrocorax aristotelis with a back-mounted GPS logger to measure position and hence ground speed, and a neck-mounted accelerometer to record wing beat frequency and strength. Local wind conditions were recorded during the deployment period. Shags always took off into the wind regardless of their intended destination and take-off duration was correlated negatively with wind speed. We combined ground speed and direction during the cruising phase with wind speed and direction to estimate air speed and direction. Whilst ground speed was highly variable, air speed was comparatively stable, although it increased significantly during strong head winds, because of stronger wing beats. The increased air speeds in head winds suggest that birds fly at the maximum range speed, not at the minimum power speed. Our study demonstrates that European shags actively adjust their flight behavior to utilize wind power to minimize the costs of take-off and cruising flight. © 2016. Published by The Company of Biologists Ltd.

Thermal Behavior of Aerospace Spur Gears in Normal and Loss-of-Lubrication Conditions

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.

2015-01-01

Testing of instrumented spur gears operating at aerospace rotorcraft conditions was conducted. The instrumented gears were operated in a normal and in a loss-of-lubrication environment. Thermocouples were utilized to measure the temperature at various locations on the test gears and a test utilized a full-field, high-speed infrared thermal imaging system. Data from thermocouples was recorded during all testing at 1 hertz. One test had the gears shrouded and a second test was run without the shrouds to permit the infrared thermal imaging system to take data during loss-of-lubrication operation. Both tests using instrumented spur gears were run in normal and loss-of-lubrication conditions. Also the result from four other loss-of-lubrication tests will be presented. In these tests two different torque levels were used while operating at the same rotational speed (10000 revolutions per minute).

Thermal Behavior of Aerospace Spur Gears in Normal and Loss-of-Lubrication Conditions

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.

2015-01-01

Testing of instrumented spur gears operating at aerospace rotorcraft conditions was conducted. The instrumented gears were operated in a normal and in a loss-of-lubrication environment. Thermocouples were utilized to measure the temperature at various locations on the test gears and a test utilized a full-field, high-speed infrared thermal imaging system. Data from thermocouples was recorded during all testing at 1 Hz. One test had the gears shrouded and a second test was run without the shrouds to permit the infrared thermal imaging system to take date during loss-of-lubrication operation. Both tests using instrumented spur gears were run in normal and loss-of-lubrication conditions. Also the result from four other loss-of-lubrication tests will be presented. In these tests two different torque levels were used while operating at the same rotational speed (10000 rpm).

Dispersed solar thermal generation employing parabolic dish-electric transport with field modulated generator systems

NASA Technical Reports Server (NTRS)

Ramakumar, R.; Bahrami, K.

1981-01-01

This paper discusses the application of field modulated generator systems (FMGS) to dispersed solar-thermal-electric generation from a parabolic dish field with electric transport. Each solar generation unit is rated at 15 kWe and the power generated by an array of such units is electrically collected for insertion into an existing utility grid. Such an approach appears to be most suitable when the heat engine rotational speeds are high (greater than 6000 r/min) and, in particular, if they are operated in the variable speed mode and if utility-grade a.c. is required for direct insertion into the grid without an intermediate electric energy storage and reconversion system. Predictions of overall efficiencies based on conservative efficiency figures for the FMGS are in the range of 25 per cent and should be encouraging to those involved in the development of cost-effective dispersed solar thermal power systems.

High-Speed On-Board Data Processing for Science Instruments

NASA Technical Reports Server (NTRS)

Beyon, Jeffrey Y.; Ng, Tak-Kwong; Lin, Bing; Hu, Yongxiang; Harrison, Wallace

2014-01-01

A new development of on-board data processing platform has been in progress at NASA Langley Research Center since April, 2012, and the overall review of such work is presented in this paper. The project is called High-Speed On-Board Data Processing for Science Instruments (HOPS) and focuses on a high-speed scalable data processing platform for three particular National Research Council's Decadal Survey missions such as Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS), Aerosol-Cloud-Ecosystems (ACE), and Doppler Aerosol Wind Lidar (DAWN) 3-D Winds. HOPS utilizes advanced general purpose computing with Field Programmable Gate Array (FPGA) based algorithm implementation techniques. The significance of HOPS is to enable high speed on-board data processing for current and future science missions with its reconfigurable and scalable data processing platform. A single HOPS processing board is expected to provide approximately 66 times faster data processing speed for ASCENDS, more than 70% reduction in both power and weight, and about two orders of cost reduction compared to the state-of-the-art (SOA) on-board data processing system. Such benchmark predictions are based on the data when HOPS was originally proposed in August, 2011. The details of these improvement measures are also presented. The two facets of HOPS development are identifying the most computationally intensive algorithm segments of each mission and implementing them in a FPGA-based data processing board. A general introduction of such facets is also the purpose of this paper.

14 CFR 23.73 - Reference landing approach speed.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reference landing approach speed. 23.73... Reference landing approach speed. (a) For normal, utility, and acrobatic category reciprocating engine-powered airplanes of 6,000 pounds or less maximum weight, the reference landing approach speed, VREF, must...

14 CFR 23.73 - Reference landing approach speed.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Reference landing approach speed. 23.73... Reference landing approach speed. (a) For normal, utility, and acrobatic category reciprocating engine-powered airplanes of 6,000 pounds or less maximum weight, the reference landing approach speed, VREF, must...

Design study of wind turbines, 50 kW to 3000 kW for electric utility applications: Executive summary

NASA Technical Reports Server (NTRS)

1977-01-01

Preliminary designs of low power (50 to 500 kW) and high power (500 to 3000 kW) wind generator systems (WGS) for electric utility applications were developed. These designs provide the bases for detail design, fabrication, and experimental demonstration testing of these units at selected utility sites. Several feasible WGS configurations were evaluated, and the concept offering the lowest energy cost potential and minimum technical risk for utility applications was selected. The selected concept was optimized utilizing a parametric computer program prepared for this purpose. The utility requirements evaluation task examined the economic, operational and institutional factors affecting the WGS in a utility environment, and provided additional guidance for the preliminary design effort. Results of the conceptual design task indicated that a rotor operating at constant speed, driving an AC generator through a gear transmission is the most cost effective WGS configuration.

Progress and prospects of silicon-based design for optical phased array

NASA Astrophysics Data System (ADS)

Hu, Weiwei; Peng, Chao; Chang-Hasnain, Connie

2016-03-01

The high-speed, high-efficient, compact phase modulator array is indispensable in the Optical-phased array (OPA) which has been considered as a promising technology for realizing flexible and efficient beam steering. In our research, two methods are presented to utilize high-contrast grating (HCG) as high-efficient phase modulator. One is that HCG possesses high-Q resonances that origins from the cancellation of leaky waves. As a result, sharp resonance peaks appear on the reflection spectrum thus HCGs can be utilized as efficient phase shifters. Another is that low-Q mode HCG is utilized as ultra-lightweight mirror. With MEMS technology, small HCG displacement (~50 nm) leads to large phase change (~1.7π). Effective beam steering is achieved in Connie Chang-Hasnian's group. On the other hand, we theoretically and experimentally investigate the system design for silicon-based optical phased array, including the star coupler, phased array, emission elements and far-field patterns. Further, the non-uniform optical phased array is presented.

An information retrieval system for research file data

Treesearch

Joan E. Lengel; John W. Koning

1978-01-01

Research file data have been successfully retrieved at the Forest Products Laboratory through a high-speed cross-referencing system involving the computer program FAMULUS as modified by the Madison Academic Computing Center at the University of Wisconsin. The method of data input, transfer to computer storage, system utilization, and effectiveness are discussed....

Trinary flip-flops using Savart plate and spatial light modulator for optical computation in multivalued logic

NASA Astrophysics Data System (ADS)

Ghosh, Amal K.; Basuray, Amitabha

2008-11-01

The memory devices in multi-valued logic are of most significance in modern research. This paper deals with the implementation of basic memory devices in multi-valued logic using Savart plate and spatial light modulator (SLM) based optoelectronic circuits. Photons are used here as the carrier to speed up the operations. Optical tree architecture (OTA) has been also utilized in the optical interconnection network. We have exploited the advantages of Savart plates, SLMs and OTA and proposed the SLM based high speed JK, D-type and T-type flip-flops in a trinary system.

Lighting Systems For High Speed Photography Applying Special Metal Halide Discharge Lamps

NASA Astrophysics Data System (ADS)

Gillum, Keith M.; Steuernagel, K. H.

1983-03-01

High speed photography requires, in addition to a good color quality of the light source, a very high level of illumination. Conventional lighting systems utilizing incandescent lamps or other metal halide lamp types has inherent problems of inefficient light output or poor color quality. Heat generated by incandescent lamps and the power these sources require drive up operating and installation costs. A most economical and practical solution was devised by using the metal halide discharge lamp developed by OSRAM, GmbH of Munich, West Germany. This lamp trade marked the HMITM Metallogen was primarily developed for the needs of the television and motion picture film industry. Due to their high efficiency and other consistent operating qualities these lamps also fulfill the needs of high speed photography, e.g. in crash test facilities, when special engineering activities are carried out. The OSRAM HMITM lamp is an AC discharge metal halide lamp with rare earth additives to increase both the efficiency and light output qualities. Since the lamp is an AC source, a special method had to be developed to overcome the strobing effect, which is normal for AC lamps given their modulated light output, when used with high speed cameras, (e.g. with >1000 fps). This method is based on an increased frequency for the lamp supply voltage coupled with a mix of the light output achieved using a multiphase mains power supply. First developed in 1977, this system using the OSRAM HMITM lamps was installed in a crash test facility of a major automotive manufacturer in West Germany. The design resulted in the best lighting and performance ever experienced. Since that time several other motor companies have made use of this breakthrough. Industrial and scientific users are now considering additional applications use of this advanced high speed lighting system.

Resveratrol Prevents High Fluence Red Light-Emitting Diode Reactive Oxygen Species-Mediated Photoinhibition of Human Skin Fibroblast Migration.

PubMed

Mamalis, Andrew; Koo, Eugene; Isseroff, R Rivkah; Murphy, William; Jagdeo, Jared

2015-01-01

Skin fibrosis is a significant medical problem that leads to a functional, aesthetic, and psychosocial impact on quality-of-life. Light-emitting diode-generated 633-nm red light (LED-RL) is part of the visible light spectrum that is not known to cause DNA damage and is considered a safe, non-invasive, inexpensive, and portable potential alternative to ultraviolet phototherapy that may change the treatment paradigm of fibrotic skin disease. The goal of our study was to investigate the how reactive oxygen species (ROS) free radicals generated by high fluence LED-RL inhibit the migration of skin fibroblasts, the main cell type involved in skin fibrosis. Fibroblast migration speed is increased in skin fibrosis, and we studied cellular migration speed of cultured human skin fibroblasts as a surrogate measure of high fluence LED-RL effect on fibroblast function. To ascertain the inhibitory role of LED-RL generated ROS on migration speed, we hypothesized that resveratrol, a potent antioxidant, could prevent the photoinhibitory effects of high fluence LED-RL on fibroblast migration speed. High fluence LED-RL generated ROS were measured by flow cytometry analysis using dihydrorhodamine (DHR). For purposes of comparison, we assessed the effects of ROS generated by hydrogen peroxide (H2O2) on fibroblast migration speed and the ability of resveratrol, a well known antioxidant, to prevent LED-RL and H2O2 generated ROS-associated changes in fibroblast migration speed. To determine whether resveratrol could prevent the high fluence LED-RL ROS-mediated photoinhibition of human skin fibroblast migration, treated cells were incubated with resveratrol at concentrations of 0.0001% and 0.001% for 24 hours, irradiated with high fluences LED-RL of 480, 640, and 800 J/cm2. High fluence LED-RL increases intracellular fibroblast ROS and decreases fibroblast migration speed. LED-RL at 480, 640 and 800 J/cm2 increased ROS levels to 132.8%, 151.0%, and 158.4% relative to matched controls, respectively. These LED-RL associated increases in ROS were prevented by pretreating cells with 0.0001% or 0.001% resveratrol. Next, we quantified the effect of hydrogen peroxide (H2O2)-associated ROS on fibroblast migration speed, and found that while H2O2-associated ROS significantly decreased relative fibroblast migration speed, pretreatment with 0.0001% or 0.001% resveratrol significantly prevented the decreases in migration speed. Furthermore, we found that LED-RL at 480, 640 and 800 J/cm2 decreased fibroblast migration speed to 83.0%, 74.4%, and 68.6% relative to matched controls, respectively. We hypothesized that these decreases in fibroblast migration speed were due to associated increases in ROS generation. Pretreatment with 0.0001% and 0.001% resveratrol prevented the LED-RL associated decreases in migration speed. High fluence LED-RL increases ROS and is associated with decreased fibroblast migration speed. We provide mechanistic support that the decreased migration speed associated with high fluence LED-RL is mediated by ROS, by demonstrating that resveratrol prevents high fluence LED-RL associated migration speed change. These data lend support to an increasing scientific body of evidence that high fluence LED-RL has anti-fibrotic properties. We hypothesize that our findings may result in a greater understanding of the fundamental mechanisms underlying visible light interaction with skin and we anticipate clinicians and other researchers may utilize these pathways for patient benefit.

Mechanical-plowing-based high-speed patterning on hard material via advanced-control and ultrasonic probe vibration.

PubMed

Wang, Zhihua; Tan, Jun; Zou, Qingze; Jiang, Wei

2013-11-01

In this paper, we present a high-speed direct pattern fabrication on hard materials (e.g., a tungsten-coated quartz substrate) via mechanical plowing. Compared to other probe-based nanolithography techniques based on chemical- and/or physical-reactions (e.g., the Dip-pen technique), mechanical plowing is meritorious for its low cost, ease of process control, and capability of working with a wide variety of materials beyond conductive and/or soft materials. However, direct patterning on hard material faces two daunting challenges. First, the patterning throughput is ultimately hindered by the "writing" (plowing) speed, which, in turn, is limited by the adverse effects that can be excited/induced during high-speed, and/or large-range plowing, including the vibrational dynamics of the actuation system (the piezoelectric actuator, the cantilever, and the mechanical fixture connecting the cantilever to the actuator), the dynamic cross-axis coupling between different axes of motion, and the hysteresis and the drift effects related to the piezoelectric actuators. Secondly, it is very challenging to directly pattern on ultra-hard materials via plowing. Even with a diamond probe, the line depth of the pattern via continuous plowing on ultra-hard materials such as tungsten, is still rather small (<0.5 nm), particularly when the "writing" speed becomes high. To overcome these two challenges, we propose to utilize a novel iterative learning control technique to achieve precision tracking of the desired pattern during high-speed, large-range plowing, and introduce ultrasonic vibration of the probe in the normal (vertical) direction during the plowing process to enable direct patterning on ultra hard materials. The proposed approach was implemented to directly fabricate patterns on a mask with tungsten coating and quartz substrate. The experimental results demonstrated that a large-size pattern of four grooves (20 μm in length with 300 nm spacing between lines) can be fabricated at a high speed of ~5 mm/s, with the line width and the line depth at ~95 nm and 2 nm, respectively. A fine pattern of the word "NANO" is also fabricated at the speed of ~5 mm/s.

Spacecraft in switch matrix for wide band service applicatons in 30/20 GHz communications satellite systems

NASA Technical Reports Server (NTRS)

Cory, B. J.

1982-01-01

Bandwidth, switching speed, off-state isolation, and reliability over a ten-year mission were factors in determining the optimum available technology for satellite communications switching in 1982. A proof of concept model for a 20 x 20 coupled crossbar switch matrix designed with FET devices for microwave switching and with high speed CMOS LIS for switch crosspoint addressing was fabricated and tested. Results show the design is feasible for application in a multichannel SS-TDMA communications system. Expandibility can readily be achieved with this design. A conceptual design study for a 100 x 100 switch matrix utilizing a coupled crossbar architecture implemented with a monolithic microwave integrated circuits revealed technology needs for high capacity switch matrices.

Peak power ratio generator

DOEpatents

Moyer, Robert D.

1985-01-01

A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

Peak power ratio generator

DOEpatents

Moyer, R.D.

A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

High-speed digital wireless battlefield network

NASA Astrophysics Data System (ADS)

Dao, Son K.; Zhang, Yongguang; Shek, Eddie C.; van Buer, Darrel

1999-07-01

In the past two years, the Digital Wireless Battlefield Network consortium that consists of HRL Laboratories, Hughes Network Systems, Raytheon, and Stanford University has participated in the DARPA TRP program to leverage the efforts in the development of commercial digital wireless products for use in the 21st century battlefield. The consortium has developed an infrastructure and application testbed to support the digitized battlefield. The consortium has implemented and demonstrated this network system. Each member is currently utilizing many of the technology developed in this program in commercial products and offerings. These new communication hardware/software and the demonstrated networking features will benefit military systems and will be applicable to the commercial communication marketplace for high speed voice/data multimedia distribution services.

Full-field high-speed laser Doppler imaging system for blood-flow measurements

NASA Astrophysics Data System (ADS)

Serov, Alexandre; Lasser, Theo

2006-02-01

We describe the design and performance of a new full-field high-speed laser Doppler imaging system developed for mapping and monitoring of blood flow in biological tissue. The total imaging time for 256x256 pixels region of interest is 1.2 seconds. An integrating CMOS image sensor is utilized to detect Doppler signal in a plurality of points simultaneously on the sample illuminated by a divergent laser beam of a uniform intensity profile. The integrating property of the detector improves the signal-to-noise ratio of the measurement, which results in high-quality flow-images provided by the system. The new technique is real-time, non-invasive and the instrument is easy to use. The wide range of applications is one of the major challenges for a future application of the imager. High-resolution high-speed laser Doppler perfusion imaging is a promising optical technique for diagnostic and assessing the treatment effect of the diseases such as e.g. atherosclerosis, psoriasis, diabetes, skin cancer, allergies, peripheral vascular diseases, skin irritancy and wound healing. We present some biological applications of the new imager and discuss the perspectives for the future implementations of the imager for clinical and physiological applications.

Design Tools for Evaluating Multiprocessor Programs

DTIC Science & Technology

1976-07-01

than large uniprocessing machines, and 2. economies of scale in manufacturing. Perhaps the most compelling reason (possibly a consequence of the...speed, redundancy, (inefficiency, resource utilization, and economies of the components. [Browne 73, Lehman 66] 6. How can the system be scheduled...mejsures are interesting about the computation? Somn may be: speed, redundancy, (inefficiency, resource utilization, and economies of the components

Real-time computational photon-counting LiDAR

NASA Astrophysics Data System (ADS)

Edgar, Matthew; Johnson, Steven; Phillips, David; Padgett, Miles

2018-03-01

The availability of compact, low-cost, and high-speed MEMS-based spatial light modulators has generated widespread interest in alternative sampling strategies for imaging systems utilizing single-pixel detectors. The development of compressed sensing schemes for real-time computational imaging may have promising commercial applications for high-performance detectors, where the availability of focal plane arrays is expensive or otherwise limited. We discuss the research and development of a prototype light detection and ranging (LiDAR) system via direct time of flight, which utilizes a single high-sensitivity photon-counting detector and fast-timing electronics to recover millimeter accuracy three-dimensional images in real time. The development of low-cost real time computational LiDAR systems could have importance for applications in security, defense, and autonomous vehicles.

Analysis and Modeling of Coronal Holes Observed by CORONAS-1. 1; Morphology and Magnetic Field Configuration

NASA Technical Reports Server (NTRS)

Obridko, Vladmir; Formichev, Valery; Kharschiladze, A. F.; Zhitnik, Igor; Slemzin, Vladmir; Hathaway, David H.; Wu, Shi T.

1998-01-01

Two low-latitude coronal holes observed by CORONAS-1 in April and June 1994 are analyzed together with magnetic field measurements obtained from Wilcox and Kitt Peak Solar Observatories. To estimate the comparable temperature of these two coronal holes, the YOHKOH observations are also utilized. Using this information, we have constructed three-dimensional magnetic field lines to illustrate the geometrical configuration of these coronal holes. The calculated synoptic maps are used to determine the existence of closed and open field regions of the hole. Finally, we have correlated the characteristics of two coronal holes with observed solar wind speed. We found that the brighter coronal hole has high speed solar wind, and the dimmer coronal hole has low speed solar wind.

Implementation of Temperature Sequential Controller on Variable Speed Drive

NASA Astrophysics Data System (ADS)

Cheong, Z. X.; Barsoum, N. N.

2008-10-01

There are many pump and motor installations with quite extensive speed variation, such as Sago conveyor, heating, ventilation and air conditioning (HVAC) and water pumping system. A common solution for these applications is to run several fixed speed motors in parallel, with flow control accomplish by turning the motors on and off. This type of control method causes high in-rush current, and adds a risk of damage caused by pressure transients. This paper explains the design and implementation of a temperature speed control system for use in industrial and commercial sectors. Advanced temperature speed control can be achieved by using ABB ACS800 variable speed drive-direct torque sequential control macro, programmable logic controller and temperature transmitter. The principle of direct torque sequential control macro (DTC-SC) is based on the control of torque and flux utilizing the stator flux field orientation over seven preset constant speed. As a result of continuous comparison of ambient temperature to the references temperatures; electromagnetic torque response is particularly fast to the motor state and it is able maintain constant speeds. Experimental tests have been carried out by using ABB ACS800-U1-0003-2, to validate the effectiveness and dynamic respond of ABB ACS800 against temperature variation, loads, and mechanical shocks.

Age, gender and deterrability: Are younger male drivers more likely to discount the future?

PubMed

Freeman, James; Kaye, Sherrie-Anne; Truelove, Verity; Davey, Jeremy

2017-07-01

Utilizing the Classical Deterrence theory and Stafford and Warr's (1993) reconceptualized model of deterrence, the current study examined whether age, gender, and discounting the future tendencies influence perceptions of being apprehended for speeding offences. Licensed motorists (N=700; 57% female) in Queensland (Australia) were recruited to complete a self-report questionnaire that measured perceptual deterrence, speeding related behaviors and discounting the future tendencies. Data were analyzed utilizing descriptive, bivariate and multivariate regressions. Significant (albeit weak) positive correlations were found between age and perceptions of apprehension certainty. Males were significantly more likely to report higher incidences of speeding (including while avoiding detection) compared to females. In contrast, females were more likely to perceive high levels of apprehension certainty and consider impending penalties to be more severe. At a multivariate level, discounting the future tendencies (in addition to being male, reporting lower levels of perceptual severity and swiftness, and more instances of punishment avoidance) were predictive of lower perceptual certainty levels. This study is one of the first to reveal that being male and having a tendency to discount the consequences of the future may directly influence drivers' perceptual deterrence levels. Copyright © 2017 Elsevier Ltd. All rights reserved.

Performance Evaluation, Emulation, and Control of Cross-Flow Hydrokinetic Turbines

NASA Astrophysics Data System (ADS)

Cavagnaro, Robert J.

Cross-flow hydrokinetic turbines are a promising option for effectively harvesting energy from fast-flowing streams or currents. This work describes the dynamics of such turbines, analyzes techniques used to scale turbine properties for prototyping, determines and demonstrates the limits of stability for cross-flow rotors, and discusses means and objectives of turbine control. Novel control strategies are under development to utilize low-speed operation (slower than at maximum power point) as a means of shedding power under rated conditions. However, operation in this regime may be unstable. An experiment designed to characterize the stability of a laboratory-scale cross-flow turbine operating near a critically low speed yields evidence that system stall (complete loss of ability to rotate) occurs due, in part, to interactions with turbulent decreases in flow speed. The turbine is capable of maintaining 'stable' operation at critical speed for short duration (typically less than 10 s), as described by exponential decay. The presence of accelerated 'bypass' flow around the rotor and decelerated 'induction' region directly upstream of the rotor, both predicted by linear momentum theory, are observed and quantified with particle image velocimetry (PIV) measurements conducted upstream of the turbine. Additionally, general agreement is seen between PIV inflow measurements and those obtained by an advection-corrected acoustic Doppler velocimeter (ADV) further upstream. Performance of a turbine at small (prototype) geometric scale may be prone to undesirable effects due to operation at low Reynolds number and in the presence of high channel blockage. Therefore, testing at larger scale, in open water is desirable. A cross-flow hydrokinetic turbine with a projected area (product of blade span and rotor diameter) of 0.7 m2 is evaluated in open-water tow trials at three inflow speeds ranging from 1.0 m/s to 2.1 m/s. Measurements of the inflow velocity, the rotor mechanical power, and electrical power output of a complete power take-off (PTO) system are utilized to determine the rotor hydrodynamic efficiency (maximum of 17%) and total system efficiency (maximum of 9%). A lab-based dynamometry method yields individual component and total PTO efficiencies, shown to have high variability and strong influence on total system efficiency. Dynamic efficiencies of PTO components can effect the overall efficiency of a turbine system, a result from field characterization. Thus, the ability to evaluate such components and their potential effects on turbine performance prior to field deployment is desirable. Before attempting control experiments with actual turbines, hardware-in-the-loop testing on controllable motor-generator sets or electromechanical emulation machines (EEMs) are explored to better understand power take-off response. The emulator control dynamic equations are presented, methods for scaling turbine parameters are developed and evaluated, and experimental results are presented from three EEMs programmed to emulate the same cross-flow turbine. Although hardware platforms and control implementations varied, results show that each EEM is successful in emulating the turbine model at different power levels, thus demonstrating the general feasibility of the approach. However, performance of motor control under torque command, current command, or speed command differed; torque methods required accurate characterization of the motors while speed methods utilized encoder feedback and more accurately tracked turbine dynamics. In a demonstration of an EEM for evaluating a hydrokinetic turbine implementation, a controller is used to track the maximum power-point of the turbine in response to turbulence. Utilizing realistic inflow conditions and control laws, the emulator dynamic speed response is shown to agree well at low frequencies with simulation but to deviate at high frequencies. The efficacy of an electromechanical emulator as an accurate representation of a fielded turbine is evaluated. A commercial horizontally-oriented cross-flow turbine is dynamically emulated on hardware to investigate control strategies and grid integration. A representative inflow time-series with a mean of 2 m/s is generated from high-resolution flow measurements of a riverine site and is used to drive emulation. Power output during emulation under similar input and loading conditions yields agreement with field measurements to within 3% at high power, near-optimal levels. Constant tip-speed ratio and constant speed proportional plus integral control schemes are compared to optimal nonlinear control and constant resistance regulation. All controllers yield similar results in terms of overall system efficiency. The emulated turbine is more responsive to turbulent inflow than the field turbine, as the model utilized to drive emulation does not account for a smoothing effect of turbulent fluctuations over the span of the fielded turbine's rotors. The turbine has a lower inertia than the demand of an isolated grid, indicating a secondary source of power with a similar frequency response is necessary if a single turbine cannot meet the entire demand. (Abstract shortened by UMI.).

Wind-tunnel investigation to determine the low speed yawing stability derivatives of a twin jet fighter model at high angles of attack

NASA Technical Reports Server (NTRS)

Coe, P. L., Jr.; Newsom, W. A., Jr.

1974-01-01

An investigation was conducted to determine the low-speed yawing stability derivatives of a twin-jet fighter airplane model at high angles of attack. Tests were performed in a low-speed tunnel utilizing variable-curvature walls to simulate pure yawing motion. The results of the study showed that at angles of attack below the stall the yawing derivatives were essentially independent of the yawing velocity and sideslip angle. However, at angles of attack above the stall some nonlinear variations were present and the derivatives were strongly dependent upon sideslip angle. The results also showed that the rolling moment due to yawing was primarily due to the wing-fuselage combination, and that at angles of attack below the stall both the vertical and horizontal tails produced significant contributions to the damping in yaw. Additionally, the tests showed that the use of the forced-oscillation data to represent the yawing stability derivatives is questionable, at high angles of attack, due to large effects arising from the acceleration in sideslip derivatives.

Integrated propulsion/energy transfer control systems for lift-fan V/STOL aircraft. [reduction of total propulsion system and control system installation requirements

NASA Technical Reports Server (NTRS)

Deckert, W. H.; Rolls, L. S.

1974-01-01

An integrated propulsion/control system for lift-fan transport aircraft is described. System behavior from full-scale experimental and piloted simulator investigations are reported. The lift-fan transport is a promising concept for short-to-medium haul civil transportation and for other missions. The lift-fan transport concept features high cruise airspeed, favorable ride qualities, small perceived noise footprints, high utilization, transportation system flexibility, and adaptability to VTOL, V/STOL, or STOL configurations. The lift-fan transport has high direct operating costs in comparison to conventional aircraft, primarily because of propulsion system and aircraft low-speed control system installation requirements. An integrated lift-fan propulsion system/aircraft low-speed control system that reduces total propulsion system and control system installation requirements is discussed.

Optimization of ultrahigh-speed multiplex PCR for forensic analysis.

PubMed

Gibson-Daw, Georgiana; Crenshaw, Karin; McCord, Bruce

2018-01-01

In this paper, we demonstrate the design and optimization of an ultrafast PCR amplification technique, used with a seven-locus multiplex that is compatible with conventional capillary electrophoresis systems as well as newer microfluidic chip devices. The procedure involves the use of a high-speed polymerase and a rapid cycling protocol to permit multiplex PCR amplification of forensic short tandem repeat loci in 6.5 min. We describe the selection and optimization of master mix reagents such as enzyme, buffer, MgCl 2 , and dNTPs, as well as primer ratios, total volume, and cycle conditions, in order to get the best profile in the shortest time possible. Sensitivity and reproducibility studies are also described. The amplification process utilizes a small high-speed thermocycler and compact laptop, making it portable and potentially useful for rapid, inexpensive on-site genotyping. The seven loci of the multiplex were taken from conventional STR genotyping kits and selected for their size and lack of overlap. Analysis was performed using conventional capillary electrophoresis and microfluidics with fluorescent detection. Overall, this technique provides a more rapid method for rapid sample screening of suspects and victims. Graphical abstract Rapid amplification of forensic DNA using high speed thermal cycling followed by capillary or microfluidic electrophoresis.

The Optimization of Trained and Untrained Image Classification Algorithms for Use on Large Spatial Datasets

NASA Technical Reports Server (NTRS)

Kocurek, Michael J.

2005-01-01

The HARVIST project seeks to automatically provide an accurate, interactive interface to predict crop yield over the entire United States. In order to accomplish this goal, large images must be quickly and automatically classified by crop type. Current trained and untrained classification algorithms, while accurate, are highly inefficient when operating on large datasets. This project sought to develop new variants of two standard trained and untrained classification algorithms that are optimized to take advantage of the spatial nature of image data. The first algorithm, harvist-cluster, utilizes divide-and-conquer techniques to precluster an image in the hopes of increasing overall clustering speed. The second algorithm, harvistSVM, utilizes support vector machines (SVMs), a type of trained classifier. It seeks to increase classification speed by applying a "meta-SVM" to a quick (but inaccurate) SVM to approximate a slower, yet more accurate, SVM. Speedups were achieved by tuning the algorithm to quickly identify when the quick SVM was incorrect, and then reclassifying low-confidence pixels as necessary. Comparing the classification speeds of both algorithms to known baselines showed a slight speedup for large values of k (the number of clusters) for harvist-cluster, and a significant speedup for harvistSVM. Future work aims to automate the parameter tuning process required for harvistSVM, and further improve classification accuracy and speed. Additionally, this research will move documents created in Canvas into ArcGIS. The launch of the Mars Reconnaissance Orbiter (MRO) will provide a wealth of image data such as global maps of Martian weather and high resolution global images of Mars. The ability to store this new data in a georeferenced format will support future Mars missions by providing data for landing site selection and the search for water on Mars.

Ultrafast wavelength multiplexed broad bandwidth digital diffuse optical spectroscopy for in vivo extraction of tissue optical properties

NASA Astrophysics Data System (ADS)

Torjesen, Alyssa; Istfan, Raeef; Roblyer, Darren

2017-03-01

Frequency-domain diffuse optical spectroscopy (FD-DOS) utilizes intensity-modulated light to characterize optical scattering and absorption in thick tissue. Previous FD-DOS systems have been limited by large device footprints, complex electronics, high costs, and limited acquisition speeds, all of which complicate access to patients in the clinical setting. We have developed a new digital DOS (dDOS) system, which is relatively compact and inexpensive, allowing for simplified clinical use, while providing unprecedented measurement speeds. The dDOS system utilizes hardware-integrated custom board-level direct digital synthesizers and an analog-to-digital converter to generate frequency sweeps and directly measure signals utilizing undersampling at six wavelengths modulated at discrete frequencies from 50 to 400 MHz. Wavelength multiplexing is utilized to achieve broadband frequency sweep measurements acquired at over 97 Hz. When compared to a gold-standard DOS system, the accuracy of optical properties recovered with the dDOS system was within 5.3% and 5.5% for absorption and reduced scattering coefficient extractions, respectively. When tested in vivo, the dDOS system was able to detect physiological changes throughout the cardiac cycle. The new FD-dDOS system is fast, inexpensive, and compact without compromising measurement quality.

The Xpress Transfer Protocol (XTP): A tutorial (expanded version)

NASA Technical Reports Server (NTRS)

Sanders, Robert M.; Weaver, Alfred C.

1990-01-01

The Xpress Transfer Protocol (XTP) is a reliable, real-time, light weight transfer layer protocol. Current transport layer protocols such as DoD's Transmission Control Protocol (TCP) and ISO's Transport Protocol (TP) were not designed for the next generation of high speed, interconnected reliable networks such as fiber distributed data interface (FDDI) and the gigabit/second wide area networks. Unlike all previous transport layer protocols, XTP is being designed to be implemented in hardware as a VLSI chip set. By streamlining the protocol, combining the transport and network layers and utilizing the increased speed and parallelization possible with a VLSI implementation, XTP will be able to provide the end-to-end data transmission rates demanded in high speed networks without compromising reliability and functionality. This paper describes the operation of the XTP protocol and in particular, its error, flow and rate control; inter-networking addressing mechanisms; and multicast support features, as defined in the XTP Protocol Definition Revision 3.4.

Amoeba-inspired nanoarchitectonic computing implemented using electrical Brownian ratchets.

PubMed

Aono, M; Kasai, S; Kim, S-J; Wakabayashi, M; Miwa, H; Naruse, M

2015-06-12

In this study, we extracted the essential spatiotemporal dynamics that allow an amoeboid organism to solve a computationally demanding problem and adapt to its environment, thereby proposing a nature-inspired nanoarchitectonic computing system, which we implemented using a network of nanowire devices called 'electrical Brownian ratchets (EBRs)'. By utilizing the fluctuations generated from thermal energy in nanowire devices, we used our system to solve the satisfiability problem, which is a highly complex combinatorial problem related to a wide variety of practical applications. We evaluated the dependency of the solution search speed on its exploration parameter, which characterizes the fluctuation intensity of EBRs, using a simulation model of our system called 'AmoebaSAT-Brownian'. We found that AmoebaSAT-Brownian enhanced the solution searching speed dramatically when we imposed some constraints on the fluctuations in its time series and it outperformed a well-known stochastic local search method. These results suggest a new computing paradigm, which may allow high-speed problem solving to be implemented by interacting nanoscale devices with low power consumption.

Solar wind iron abundance variations at solar wind speeds up to 600 km s sup -1, 1972 to 1976

NASA Technical Reports Server (NTRS)

Mitchell, D. G.; Roelof, E. C.; Bame, S. J.

1982-01-01

The Fe/H ratios in the peaks of high speed streams (HSS) were analyzed during the decline of Solar Cycle 20 and the following minimum (October 1972 to December 1976). The response of the 50 to 200 keV ion channel of the APL/JHU energetic particle experiment (EPE) on IMP-7 and 8 was utilized to solar wind iron ions at high solar wind speeds (V or = 600 km/sec). Fe measurements with solar wind H and He parameters were compared from the Los Alamos National Laboratory (LANL) instruments on the same spacecraft. In general, the Fe distribution parameters (bulk velocity, flow direction, temperature) are found to be similar to the LANL He parameters. Although the average Fe/H ration in many steady HSS peaks agrees within observational uncertainties with the nominal coronal ratio of 4.7 x 0.00001, abundance variations of a factor of up to 6 are obtained across a given coronal-hole associated HSS.

Mining of high utility-probability sequential patterns from uncertain databases

PubMed Central

Zhang, Binbin; Fournier-Viger, Philippe; Li, Ting

2017-01-01

High-utility sequential pattern mining (HUSPM) has become an important issue in the field of data mining. Several HUSPM algorithms have been designed to mine high-utility sequential patterns (HUPSPs). They have been applied in several real-life situations such as for consumer behavior analysis and event detection in sensor networks. Nonetheless, most studies on HUSPM have focused on mining HUPSPs in precise data. But in real-life, uncertainty is an important factor as data is collected using various types of sensors that are more or less accurate. Hence, data collected in a real-life database can be annotated with existing probabilities. This paper presents a novel pattern mining framework called high utility-probability sequential pattern mining (HUPSPM) for mining high utility-probability sequential patterns (HUPSPs) in uncertain sequence databases. A baseline algorithm with three optional pruning strategies is presented to mine HUPSPs. Moroever, to speed up the mining process, a projection mechanism is designed to create a database projection for each processed sequence, which is smaller than the original database. Thus, the number of unpromising candidates can be greatly reduced, as well as the execution time for mining HUPSPs. Substantial experiments both on real-life and synthetic datasets show that the designed algorithm performs well in terms of runtime, number of candidates, memory usage, and scalability for different minimum utility and minimum probability thresholds. PMID:28742847

Force interaction and 3D pole movement in double poling.

PubMed

Stöggl, T; Holmberg, H-C

2011-12-01

The aim of this study was to analyze double poling using combined kinetic and 3D kinematic analysis at high skiing speeds as regards pole force components, pole angles and pole behavior during the poling and swing phase. The hypothesis was that a horizontal pole force is more predictive for maximal skiing speed (V(max)) than the resultant pole force. Sixteen elite skiers performed a double-poling V(max) test while treadmill roller skiing. Pole forces and 3D kinematics of pole movement at a speed of 30 km/h were analyzed and related to V(max). The duration of the "preparation phase" showed the strongest relationship with V(max) (r=0.87, P<0.001). Faster skiers generated longer cycle lengths with longer swing and poling times, had less inclined pole angles at pole plant and a later peak pole force. Horizontal pole forces were not more highly related to V(max) compared with the resultant pole force. Impact force was not related to V(max). At high skiing speeds, skiers should aim to combine high pole forces with appropriate timing of pole forces and appropriate pole and body positions during the swing and poling phase. The emphasis in training should be on the development of specific strength capacities for pole force production and the utilization of these capacities in double-poling training sessions. © 2011 John Wiley & Sons A/S.

A Nonlinear Dynamics Approach for Incorporating Wind-Speed Patterns into Wind-Power Project Evaluation

PubMed Central

Huffaker, Ray; Bittelli, Marco

2015-01-01

Wind-energy production may be expanded beyond regions with high-average wind speeds (such as the Midwest U.S.A.) to sites with lower-average speeds (such as the Southeast U.S.A.) by locating favorable regional matches between natural wind-speed and energy-demand patterns. A critical component of wind-power evaluation is to incorporate wind-speed dynamics reflecting documented diurnal and seasonal behavioral patterns. Conventional probabilistic approaches remove patterns from wind-speed data. These patterns must be restored synthetically before they can be matched with energy-demand patterns. How to accurately restore wind-speed patterns is a vexing problem spurring an expanding line of papers. We propose a paradigm shift in wind power evaluation that employs signal-detection and nonlinear-dynamics techniques to empirically diagnose whether synthetic pattern restoration can be avoided altogether. If the complex behavior of observed wind-speed records is due to nonlinear, low-dimensional, and deterministic system dynamics, then nonlinear dynamics techniques can reconstruct wind-speed dynamics from observed wind-speed data without recourse to conventional probabilistic approaches. In the first study of its kind, we test a nonlinear dynamics approach in an application to Sugarland Wind—the first utility-scale wind project proposed in Florida, USA. We find empirical evidence of a low-dimensional and nonlinear wind-speed attractor characterized by strong temporal patterns that match up well with regular daily and seasonal electricity demand patterns. PMID:25617767

Container System Hardware Status Report

DTIC Science & Technology

1986-01-01

includes the proureentofeight SL-7 class high - speed containerships and their Subsequent conversion to a cargo configuration specifically designed for...wide, 53.5-in high , 242-in long, and Weighs 4,000 lbs. The MILVAN chassis were competitively procured from incustry utilizing a performance military...accept load transfer from a cargo ship and equipped with a ramp for Roll On/Roll Off (RO/RO) discharge systems. The LAMP-H will :1replace the LARC-LX

Defense Conversion Redirecting R and D

DTIC Science & Technology

1993-05-01

agree that maglev or high members aerospace companies, utilities, univer- speed rail systems are probably limited to a few sities, small high tech...200 years. Even maglev a 3-year period for France’s TGV with a manufac- trains, long the favorite technology of the future turing workforce for the...population density. Maglev might parts of the United States, but on the basis of the contribute to the advance of some technologies, preliminary

An update of commercial infrared sensing and imaging instruments

NASA Technical Reports Server (NTRS)

Kaplan, Herbert

1989-01-01

A classification of infrared sensing instruments by type and application, listing commercially available instruments, from single point thermal probes to on-line control sensors, to high speed, high resolution imaging systems is given. A review of performance specifications follows, along with a discussion of typical thermographic display approaches utilized by various imager manufacturers. An update report on new instruments, new display techniques and newly introduced features of existing instruments is given.

Semiconductor laser joint study program with Rome Laboratory

NASA Astrophysics Data System (ADS)

Schaff, William J.; Okeefe, Sean S.; Eastman, Lester F.

1994-09-01

A program to jointly study vertical-cavity surface emitting lasers (VCSEL) for high speed vertical optical interconnects (VOI) has been conducted under an ES&E between Rome Laboratory and Cornell University. Lasers were designed, grown, and fabricated at Cornell University. A VCSEL measurement laboratory has been designed, built, and utilized at Rome Laboratory. High quality VCSEL material was grown and characterized by fabricating conventional lateral cavity lasers that emitted at the design wavelength of 1.04 microns. The VCSEL's emit at 1.06 microns. Threshold currents of 16 mA at 4.8 volts were obtained for 30 microns diameter devices. Output powers of 5 mW were measured. This is 500 times higher power than from the light emitting diodes employed previously for vertical optical interconnects. A new form of compositional grading using a cosinusoidal function has been developed and is very successful for reducing diode series resistance for high speed interconnection applications. A flip-chip diamond package compatible with high speed operation of 16 VCSEL elements has been designed and characterized. A flip-chip device binding effort at Rome Laboratory was also designed and initiated. This report presents details of the one-year effort, including process recipes and results.

Reflectively Coupled Waveguide Photodetector for High Speed Optical Interconnection

PubMed Central

Hsu*, Shih-Hsiang

2010-01-01

To fully utilize GaAs high drift mobility, techniques to monolithically integrate In0.53Ga0.47As p-i-n photodetectors with GaAs based optical waveguides using total internal reflection coupling are reviewed. Metal coplanar waveguides, deposited on top of the polyimide layer for the photodetector’s planarization and passivation, were then uniquely connected as a bridge between the photonics and electronics to illustrate the high-speed monitoring function. The photodetectors were efficiently implemented and imposed on the echelle grating circle for wavelength division multiplexing monitoring. In optical filtering performance, the monolithically integrated photodetector channel spacing was 2 nm over the 1,520–1,550 nm wavelength range and the pass band was 1 nm at the −1 dB level. For high-speed applications the full-width half-maximum of the temporal response and 3-dB bandwidth for the reflectively coupled waveguide photodetectors were demonstrated to be 30 ps and 11 GHz, respectively. The bit error rate performance of this integrated photodetector at 10 Gbit/s with 27-1 long pseudo-random bit sequence non-return to zero input data also showed error-free operation. PMID:22163502

High-speed holographic correlation system by a time-division recording method for copyright content management on the internet

NASA Astrophysics Data System (ADS)

Watanabe, Eriko; Ikeda, Kanami; Kodate, Kashiko

2012-10-01

Using a holographic disc memory on which a huge amount of data can be stored, we constructed an ultra-high-speed, all-optical correlation system. In this method, multiplex recording is, however, restricted to "one page" on "one spot." In addition, signal information must be normalized as data of the same size, even if the object data size is smaller. Therefore, this system is difficult to apply to part of the object data scene (i.e., partial scene searching and template matching), while maintaining high accessibility and programmability. In this paper, we develop a holographic correlation system by a time division recording method that increases the number of multiplex recordings on the same spot. Assuming that a four-channel detector is utilized, 15 parallel correlations are achieved by a time-division recording method. Preliminary correlation experiments with the holographic optical disc setup are carried out by high correlation peaks at a rotational speed of 300 rpm. We also describe the combination of an optical correlation system for copyright content management that searches the Internet and detects illegal contents on video sharing websites.

Characterization of calculus migration during Ho:YAG laser lithotripsy by high speed camera using suspended pendulum method

NASA Astrophysics Data System (ADS)

Zhang, Jian James; Rajabhandharaks, Danop; Xuan, Jason Rongwei; Chia, Ray W. J.; Hasenberg, Tom

2014-03-01

Calculus migration is a common problem during ureteroscopic laser lithotripsy procedure to treat urolithiasis. A conventional experimental method to characterize calculus migration utilized a hosting container (e.g. a "V" grove or a test tube). These methods, however, demonstrated large variation and poor detectability, possibly attributing to friction between the calculus and the container on which the calculus was situated. In this study, calculus migration was investigated using a pendulum model suspended under water to eliminate the aforementioned friction. A high speed camera was used to study the movement of the calculus which covered zero order (displacement), 1st order (speed) and 2nd order (acceleration). A commercialized, pulsed Ho:YAG laser at 2.1 um, 365-um core fiber, and calculus phantom (Plaster of Paris, 10×10×10mm cube) were utilized to mimic laser lithotripsy procedure. The phantom was hung on a stainless steel bar and irradiated by the laser at 0.5, 1.0 and 1.5J energy per pulse at 10Hz for 1 second (i.e., 5, 10, and 15W). Movement of the phantom was recorded by a high-speed camera with a frame rate of 10,000 FPS. Maximum displacement was 1.25+/-0.10, 3.01+/-0.52, and 4.37+/-0.58 mm for 0.5, 1, and 1.5J energy per pulse, respectively. Using the same laser power, the conventional method showed <0.5 mm total displacement. When reducing the phantom size to 5×5×5mm (1/8 in volume), the displacement was very inconsistent. The results suggested that using the pendulum model to eliminate the friction improved sensitivity and repeatability of the experiment. Detailed investigation on calculus movement and other causes of experimental variation will be conducted as a future study.

RAMICS: trainable, high-speed and biologically relevant alignment of high-throughput sequencing reads to coding DNA

PubMed Central

Wright, Imogen A.; Travers, Simon A.

2014-01-01

The challenge presented by high-throughput sequencing necessitates the development of novel tools for accurate alignment of reads to reference sequences. Current approaches focus on using heuristics to map reads quickly to large genomes, rather than generating highly accurate alignments in coding regions. Such approaches are, thus, unsuited for applications such as amplicon-based analysis and the realignment phase of exome sequencing and RNA-seq, where accurate and biologically relevant alignment of coding regions is critical. To facilitate such analyses, we have developed a novel tool, RAMICS, that is tailored to mapping large numbers of sequence reads to short lengths (<10 000 bp) of coding DNA. RAMICS utilizes profile hidden Markov models to discover the open reading frame of each sequence and aligns to the reference sequence in a biologically relevant manner, distinguishing between genuine codon-sized indels and frameshift mutations. This approach facilitates the generation of highly accurate alignments, accounting for the error biases of the sequencing machine used to generate reads, particularly at homopolymer regions. Performance improvements are gained through the use of graphics processing units, which increase the speed of mapping through parallelization. RAMICS substantially outperforms all other mapping approaches tested in terms of alignment quality while maintaining highly competitive speed performance. PMID:24861618

A home-built digital optical MRI console using high-speed serial links.

PubMed

Tang, Weinan; Wang, Weimin; Liu, Wentao; Ma, Yajun; Tang, Xin; Xiao, Liang; Gao, Jia-Hong

2015-08-01

To develop a high performance, cost-effective digital optical console for scalable multichannel MRI. The console system was implemented with flexibility and efficiency based on a modular architecture with distributed pulse sequencers. High-speed serial links were optimally utilized to interconnect the system, providing fast digital communication with a multi-gigabit data rate. The conventional analog radio frequency (RF) chain was replaced with a digital RF manipulation. The acquisition electronics were designed in close proximity to RF coils and preamplifiers, using a digital optical link to transmit the MR signal. A prototype of the console was constructed with a broad frequency range from direct current to 100 MHz. A temporal resolution of 1 μs was achieved for both the RF and gradient operations. The MR signal was digitized in the scanner room with an overall dynamic range between 16 and 24 bits and was transmitted to a master controller over a duplex optic fiber with a high data rate of 3.125 gigabits per second. High-quality phantom and human images were obtained using the prototype on both 0.36T and 1.5T clinical MRI scanners. A homemade digital optical MRI console with high-speed serial interconnection has been developed to better serve imaging research and clinical applications. © 2014 Wiley Periodicals, Inc.

Large amplitude forcing of a high speed 2-dimensional jet

NASA Technical Reports Server (NTRS)

Bernal, L.; Sarohia, V.

1984-01-01

The effect of large amplitude forcing on the growth of a high speed two dimensional jet was investigated experimentally. Two forcing techniques were utilized: mass flow oscillations and a mechanical system. The mass flow oscillation tests were conducted at Strouhal numbers from 0.00052 to 0.045, and peak to peak amplitudes up to 50 percent of the mean exit velocity. The exit Mach number was varied in the range 0.15 to 0.8. The corresponding Reynolds numbers were 8,400 and 45,000. The results indicate no significant change of the jet growth rate or centerline velocity decay compared to the undisturbed free jet. The mechanical forcing system consists of two counter rotating hexagonal cylinders located parallel to the span of the nozzle. Forcing frequencies up to 1,500 Hz were tested. Both symmetric and antisymmetric forcing can be implemented. The results for antisymmetric forcing showed a significant (75 percent) increase of the jet growth rate at an exit Mach number of 0.25 and a Strouhal number of 0.019. At higher rotational speeds, the jet deflected laterally. A deflection angle of 39 deg with respect to the centerline was measured at the maximum rotational speed.

Analysis of the electrical harmonic characteristics of a slip recovery variable speed generating system for wind turbine applications

NASA Astrophysics Data System (ADS)

Herrera, J. I.; Reddoch, T. W.

1988-02-01

Variable speed electric generating technology can enhance the general use of wind energy in electric utility applications. This enhancement results from two characteristic properties of variable speed wind turbine generators: an improvement in drive train damping characteristics, which results in reduced structural loading on the entire wind turbine system, and an improvement in the overall efficiency by using a more sophisticated electrical generator. Electronic converter systems are the focus of this investigation -- in particular, the properties of a wound-rotor induction generator with the slip recovery system and direct-current link converter. Experience with solid-state converter systems in large wind turbines is extremely limited. This report presents measurements of electrical performances of the slip recovery system and is limited to the terminal characteristics of the system. Variable speed generating systems working effectively in utility applications will require a satisfactory interface between the turbine/generator pair and the utility network. The electrical testing described herein focuses largely on the interface characteristics of the generating system. A MOD-O wind turbine was connected to a very strong system; thus, the voltage distortion was low and the total harmonic distortion in the utility voltage was less than 3 percent (within the 5 percent limit required by most utilities). The largest voltage component of a frequency below 60 Hz was 40 dB down from the 60-Hz less than component.

High-speed and high-resolution quantitative phase imaging with digital-micromirror device-based illumination (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhou, Renjie; Jin, Di; Yaqoob, Zahid; So, Peter T. C.

2017-02-01

Due to the large number of available mirrors, the patterning speed, low-cost, and compactness, digital-micromirror devices (DMDs) have been extensively used in biomedical imaging system. Recently, DMDs have been brought to the quantitative phase microscopy (QPM) field to achieve synthetic-aperture imaging and tomographic imaging. Last year, our group demonstrated using DMD for QPM, where the phase-retrieval is based on a recently developed Fourier ptychography algorithm. In our previous system, the illumination angle was varied through coding the aperture plane of the illumination system, which has a low efficiency on utilizing the laser power. In our new DMD-based QPM system, we use the Lee-holograms, which is conjugated to the sample plane, to change the illumination angles for much higher power efficiency. Multiple-angle illumination can also be achieved with this method. With this versatile system, we can achieve FPM-based high-resolution phase imaging with 250 nm lateral resolution using the Rayleigh criteria. Due to the use of a powerful laser, the imaging speed would only be limited by the camera acquisition speed. With a fast camera, we expect to achieve close to 100 fps phase imaging speed that has not been achieved in current FPM imaging systems. By adding reference beam, we also expect to achieve synthetic-aperture imaging while directly measuring the phase of the sample fields. This would reduce the phase-retrieval processing time to allow for real-time imaging applications in the future.

High-brightness laser imaging with tunable speckle reduction enabled by electroactive micro-optic diffusers.

PubMed

Farrokhi, Hamid; Rohith, Thazhe Madam; Boonruangkan, Jeeranan; Han, Seunghwoi; Kim, Hyunwoong; Kim, Seung-Woo; Kim, Young-Jin

2017-11-10

High coherence of lasers is desirable in high-speed, high-resolution, and wide-field imaging. However, it also causes unavoidable background speckle noise thus degrades the image quality in traditional microscopy and more significantly in interferometric quantitative phase imaging (QPI). QPI utilizes optical interference for high-precision measurement of the optical properties where the speckle can severely distort the information. To overcome this, we demonstrated a light source system having a wide tunability in the spatial coherence over 43% by controlling the illumination angle, scatterer's size, and the rotational speed of an electroactive-polymer rotational micro-optic diffuser. Spatially random phase modulation was implemented for the lower speckle imaging with over a 50% speckle reduction without a significant degradation in the temporal coherence. Our coherence control technique will provide a unique solution for a low-speckle, full-field, and coherent imaging in optically scattering media in the fields of healthcare sciences, material sciences and high-precision engineering.

Load speed regulation in compliant mechanical transmission systems using feedback and feedforward control actions.

PubMed

Raul, P R; Dwivedula, R V; Pagilla, P R

2016-07-01

The problem of controlling the load speed of a mechanical transmission system consisting of a belt-pulley and gear-pair is considered. The system is modeled as two inertia (motor and load) connected by a compliant transmission. If the transmission is assumed to be rigid, then using either the motor or load speed feedback provides the same result. However, with transmission compliance, due to belts or long shafts, the stability characteristics and performance of the closed-loop system are quite different when either motor or load speed feedback is employed. We investigate motor and load speed feedback schemes by utilizing the singular perturbation method. We propose and discuss a control scheme that utilizes both motor and load speed feedback, and design an adaptive feedforward action to reject load torque disturbances. The control algorithms are implemented on an experimental platform that is typically used in roll-to-roll manufacturing and results are shown and discussed. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Understanding the Benefits and Limitations of Increasing Maximum Rotor Tip Speed for Utility-Scale Wind Turbines

NASA Astrophysics Data System (ADS)

Ning, A.; Dykes, K.

2014-06-01

For utility-scale wind turbines, the maximum rotor rotation speed is generally constrained by noise considerations. Innovations in acoustics and/or siting in remote locations may enable future wind turbine designs to operate with higher tip speeds. Wind turbines designed to take advantage of higher tip speeds are expected to be able to capture more energy and utilize lighter drivetrains because of their decreased maximum torque loads. However, the magnitude of the potential cost savings is unclear, and the potential trade-offs with rotor and tower sizing are not well understood. A multidisciplinary, system-level framework was developed to facilitate wind turbine and wind plant analysis and optimization. The rotors, nacelles, and towers of wind turbines are optimized for minimum cost of energy subject to a large number of structural, manufacturing, and transportation constraints. These optimization studies suggest that allowing for higher maximum tip speeds could result in a decrease in the cost of energy of up to 5% for land-based sites and 2% for offshore sites when using current technology. Almost all of the cost savings are attributed to the decrease in gearbox mass as a consequence of the reduced maximum rotor torque. Although there is some increased energy capture, it is very minimal (less than 0.5%). Extreme increases in tip speed are unnecessary; benefits for maximum tip speeds greater than 100-110 m/s are small to nonexistent.

A high velocity impact experiment of micro-scale ice particles using laser-driven system

NASA Astrophysics Data System (ADS)

Yu, Hyeonju; Kim, Jungwook; Yoh, Jack J.

2014-11-01

A jet engine for high speed air breathing propulsion is subject to continuous wear as a result of impacts of micro-scale ice particles during a flight in the atmosphere. The inlet duct and compressor blades are exposed to on-coming frozen moisture particles that may result in the surface damage and significantly shorten the designed lifetime of the aircraft. Under such prolonged high-speed impact loading, the performance parameters such as flight instability and power loss of a jet engine can be significantly degraded. In this work, a laser-driven system was designed to accelerate micro-scale ice particles to the velocity up to Mach 2 using a Q-switched Nd:YAG laser beam at 100-600 mJ with 1064 nm wavelength and 9 ns pulse duration. The high speed images (Phantom v711) and double exposure shadowgraphs were used to calculate the average velocity of ice particles and their deceleration. Velocity Interferometer System for Any Reflector measurements were also utilized for the analysis of free surface velocity of a metal foil in order to understand the interfacial dynamics between the impacting particles and accepting metal target. The velocity of our ice particles is sufficiently fast for studying the effect of moisture particle collision on an air-breathing duct of high speed aircraft, and thus the results can provide insight into how minute space debris or micrometeorites cause damage to the orbiting spacecraft at large.

Frequency domain laser velocimeter signal processor: A new signal processing scheme

NASA Technical Reports Server (NTRS)

Meyers, James F.; Clemmons, James I., Jr.

1987-01-01

A new scheme for processing signals from laser velocimeter systems is described. The technique utilizes the capabilities of advanced digital electronics to yield a smart instrument that is able to configure itself, based on the characteristics of the input signals, for optimum measurement accuracy. The signal processor is composed of a high-speed 2-bit transient recorder for signal capture and a combination of adaptive digital filters with energy and/or zero crossing detection signal processing. The system is designed to accept signals with frequencies up to 100 MHz with standard deviations up to 20 percent of the average signal frequency. Results from comparative simulation studies indicate measurement accuracies 2.5 times better than with a high-speed burst counter, from signals with as few as 150 photons per burst.

Fluid Mechanics, Drag Reduction and Advanced Configuration Aeronautics

NASA Technical Reports Server (NTRS)

Bushnell, Dennis M.

2000-01-01

This paper discusses Advanced Aircraft configurational approaches across the speed range, which are either enabled, or greatly enhanced, by clever Flow Control. Configurations considered include Channel Wings with circulation control for VTOL (but non-hovering) operation with high cruise speed, strut-braced CTOL transports with wingtip engines and extensive ('natural') laminar flow control, a midwing double fuselage CTOL approach utilizing several synergistic methods for drag-due-to-lift reduction, a supersonic strut-braced configuration with order of twice the L/D of current approaches and a very advanced, highly engine flow-path-integrated hypersonic cruise machine. This paper indicates both the promise of synergistic flow control approaches as enablers for 'Revolutions' in aircraft performance and fluid mechanic 'areas of ignorance' which impede their realization and provide 'target-rich' opportunities for Fluids Research.

Microfog lubrication for aircraft engine bearings

NASA Technical Reports Server (NTRS)

Rosenlieb, J. W.

1976-01-01

An analysis and system study was performed to provide design information regarding lubricant and coolant flow rates and flow paths for effective utilization of the lubricant and coolant in a once through bearing oil mist (microfog) and coolant air system. Both static and dynamic tests were performed. Static tests were executed to evaluate and calibrate the mist supply system. A total of thirteen dynamic step speed bearing tests were performed using four different lubricants and several different mist and air supply configurations. The most effective configuration consisted of supplying the mist and the major portion of the cooling air axially through the bearing. The results of these tests have shown the feasibility of using a once through oil mist and cooling air system to lubricate and cool a high speed, high temperature aircraft engine mainshaft bearing.

A New Test Method of Circuit Breaker Spring Telescopic Characteristics Based Image Processing

NASA Astrophysics Data System (ADS)

Huang, Huimin; Wang, Feifeng; Lu, Yufeng; Xia, Xiaofei; Su, Yi

2018-06-01

This paper applied computer vision technology to the fatigue condition monitoring of springs, and a new telescopic characteristics test method is proposed for circuit breaker operating mechanism spring based on image processing technology. High-speed camera is utilized to capture spring movement image sequences when high voltage circuit breaker operated. Then the image-matching method is used to obtain the deformation-time curve and speed-time curve, and the spring expansion and deformation parameters are extracted from it, which will lay a foundation for subsequent spring force analysis and matching state evaluation. After performing simulation tests at the experimental site, this image analyzing method could solve the complex problems of traditional mechanical sensor installation and monitoring online, status assessment of the circuit breaker spring.

Spectrum slicer for snapshot spectral imaging

NASA Astrophysics Data System (ADS)

Tamamitsu, Miu; Kitagawa, Yutaro; Nakagawa, Keiichi; Horisaki, Ryoichi; Oishi, Yu; Morita, Shin-ya; Yamagata, Yutaka; Motohara, Kentaro; Goda, Keisuke

2015-12-01

We propose and demonstrate an optical component that overcomes critical limitations in our previously demonstrated high-speed multispectral videography-a method in which an array of periscopes placed in a prism-based spectral shaper is used to achieve snapshot multispectral imaging with the frame rate only limited by that of an image-recording sensor. The demonstrated optical component consists of a slicing mirror incorporated into a 4f-relaying lens system that we refer to as a spectrum slicer (SS). With its simple design, we can easily increase the number of spectral channels without adding fabrication complexity while preserving the capability of high-speed multispectral videography. We present a theoretical framework for the SS and its experimental utility to spectral imaging by showing real-time monitoring of a dynamic colorful event through five different visible windows.

Design and Implementation of Hybrid CORDIC Algorithm Based on Phase Rotation Estimation for NCO

PubMed Central

Zhang, Chaozhu; Han, Jinan; Li, Ke

2014-01-01

The numerical controlled oscillator has wide application in radar, digital receiver, and software radio system. Firstly, this paper introduces the traditional CORDIC algorithm. Then in order to improve computing speed and save resources, this paper proposes a kind of hybrid CORDIC algorithm based on phase rotation estimation applied in numerical controlled oscillator (NCO). Through estimating the direction of part phase rotation, the algorithm reduces part phase rotation and add-subtract unit, so that it decreases delay. Furthermore, the paper simulates and implements the numerical controlled oscillator by Quartus II software and Modelsim software. Finally, simulation results indicate that the improvement over traditional CORDIC algorithm is achieved in terms of ease of computation, resource utilization, and computing speed/delay while maintaining the precision. It is suitable for high speed and precision digital modulation and demodulation. PMID:25110750

Lubrication of Space Shuttle Main Engine Turbopump Bearings

NASA Technical Reports Server (NTRS)

Gibson, Howard; Munafo, Paul (Technical Monitor)

2001-01-01

The Space Shuttle has three main engines that are used for propulsion into orbit. These engines are fed propellants by four turbopumps on each engine. A main element in the turbopump is the bearings supporting the rotor that spins the turbine blades and the pump impeller. These bearings are required to spin at very high speeds, support radial and thrust loads, and have high wear resistance without the benefit of lubrication. The liquid hydrogen and oxygen propellants flow through the bearings to cool the surfaces. The volatile nature of the propellants excludes any conventional means of lubrication. Lubrication for these bearings is provided by the ball separator inside the bearing. The separator is a composite material that supplies a transfer film of lubrication to the rings and balls. New separator materials and lubrication schemes have been investigated at Marshall Space Flight Center in a bearing test rig with promising results. Hybrid bearings with silicon nitride balls have also been evaluated. The use of hybrid, silicon nitride ball bearings in conjunction -with better separator materials has shown excellent results. The work that Marshall has done is being utilized in turbopumps flying on the space shuttle fleet and will be utilized in future space travel. This result of this work is valuable for all aerospace and commercial applications where high-speed bearings are used.

A Neutron Diffractometer for a Long Pulsed Neutron Source

NASA Astrophysics Data System (ADS)

Sokol, Paul; Wang, Cailin

Long pulsed neutron sources are being actively developed as small university based sources and are being considered for the next generation of high powered sources, such as the European Neutron Source (ESS) and the Spallation Neutron Source (SNS) second target station. New instrumentation concepts will be required to effectively utilize the full spectrum of neutrons generated by these sources. Neutron diffractometers, which utilize time-of-flight (TOF) techniques for wavelength resolution, are particularly problematic. We describe an instrument for a long pulsed source that provides resolution comparable to that obtained on short pulsed sources without the need of long incident flight paths. We accomplish this by utilizing high speed choppers to impose a time structure on the spectrum of incident neutrons. By strategically positioning these choppers the response matrix assumes a convenient form that can be deconvoluted from the measured TOF spectrum to produce the diffraction pattern of the sample. We compare the performance of this instrument to other possible diffraction instruments that could be utilized on a long pulsed source.

Speed over efficiency: locusts select body temperatures that favour growth rate over efficient nutrient utilization

PubMed Central

Miller, Gabriel A.; Clissold, Fiona J.; Mayntz, David; Simpson, Stephen J.

2009-01-01

Ectotherms have evolved preferences for particular body temperatures, but the nutritional and life-history consequences of such temperature preferences are not well understood. We measured thermal preferences in Locusta migratoria (migratory locusts) and used a multi-factorial experimental design to investigate relationships between growth/development and macronutrient utilization (conversion of ingesta to body mass) as a function of temperature. A range of macronutrient intake values for insects at 26, 32 and 38°C was achieved by offering individuals high-protein diets, high-carbohydrate diets or a choice between both. Locusts placed in a thermal gradient selected temperatures near 38°C, maximizing rates of weight gain; however, this enhanced growth rate came at the cost of poor protein and carbohydrate utilization. Protein and carbohydrate were equally digested across temperature treatments, but once digested both macronutrients were converted to growth most efficiently at the intermediate temperature (32°C). Body temperature preference thus yielded maximal growth rates at the expense of efficient nutrient utilization. PMID:19625322

An investigation of the speeding-related crash designation through crash narrative reviews sampled via logistic regression.

PubMed

Fitzpatrick, Cole D; Rakasi, Saritha; Knodler, Michael A

2017-01-01

Speed is one of the most important factors in traffic safety as higher speeds are linked to increased crash risk and higher injury severities. Nearly a third of fatal crashes in the United States are designated as "speeding-related", which is defined as either "the driver behavior of exceeding the posted speed limit or driving too fast for conditions." While many studies have utilized the speeding-related designation in safety analyses, no studies have examined the underlying accuracy of this designation. Herein, we investigate the speeding-related crash designation through the development of a series of logistic regression models that were derived from the established speeding-related crash typologies and validated using a blind review, by multiple researchers, of 604 crash narratives. The developed logistic regression model accurately identified crashes which were not originally designated as speeding-related but had crash narratives that suggested speeding as a causative factor. Only 53.4% of crashes designated as speeding-related contained narratives which described speeding as a causative factor. Further investigation of these crashes revealed that the driver contributing code (DCC) of "driving too fast for conditions" was being used in three separate situations. Additionally, this DCC was also incorrectly used when "exceeding the posted speed limit" would likely have been a more appropriate designation. Finally, it was determined that the responding officer only utilized one DCC in 82% of crashes not designated as speeding-related but contained a narrative indicating speed as a contributing causal factor. The use of logistic regression models based upon speeding-related crash typologies offers a promising method by which all possible speeding-related crashes could be identified. Published by Elsevier Ltd.

Real-time fuzzy inference based robot path planning

NASA Technical Reports Server (NTRS)

Pacini, Peter J.; Teichrow, Jon S.

1990-01-01

This project addresses the problem of adaptive trajectory generation for a robot arm. Conventional trajectory generation involves computing a path in real time to minimize a performance measure such as expended energy. This method can be computationally intensive, and it may yield poor results if the trajectory is weakly constrained. Typically some implicit constraints are known, but cannot be encoded analytically. The alternative approach used here is to formulate domain-specific knowledge, including implicit and ill-defined constraints, in terms of fuzzy rules. These rules utilize linguistic terms to relate input variables to output variables. Since the fuzzy rulebase is determined off-line, only high-level, computationally light processing is required in real time. Potential applications for adaptive trajectory generation include missile guidance and various sophisticated robot control tasks, such as automotive assembly, high speed electrical parts insertion, stepper alignment, and motion control for high speed parcel transfer systems.

High-efficiency exfoliation of large-area mono-layer graphene oxide with controlled dimension.

PubMed

Park, Won Kyu; Yoon, Yeojoon; Song, Young Hyun; Choi, Su Yeon; Kim, Seungdu; Do, Youngjin; Lee, Junghyun; Park, Hyesung; Yoon, Dae Ho; Yang, Woo Seok

2017-11-27

In this work, we introduce a novel and facile method of exfoliating large-area, single-layer graphene oxide using a shearing stress. The shearing stress reactor consists of two concentric cylinders, where the inner cylinder rotates at controlled speed while the outer cylinder is kept stationary. We found that the formation of Taylor vortex flow with shearing stress can effectively exfoliate the graphite oxide, resulting in large-area single- or few-layer graphene oxide (GO) platelets with high yields (>90%) within 60 min of reaction time. Moreover, the lateral size of exfoliated GO sheets was readily tunable by simply controlling the rotational speed of the reactor and reaction time. Our approach for high-efficiency exfoliation of GO with controlled dimension may find its utility in numerous industrial applications including energy storage, conducting composite, electronic device, and supporting frameworks of catalyst.

An arc tangent function demodulation method of fiber-optic Fabry-Perot high-temperature pressure sensor

NASA Astrophysics Data System (ADS)

Ren, Qianyu; Li, Junhong; Hong, Yingping; Jia, Pinggang; Xiong, Jijun

2017-09-01

A new demodulation algorithm of the fiber-optic Fabry-Perot cavity length based on the phase generated carrier (PGC) is proposed in this paper, which can be applied in the high-temperature pressure sensor. This new algorithm based on arc tangent function outputs two orthogonal signals by utilizing an optical system, which is designed based on the field-programmable gate array (FPGA) to overcome the range limit of the original PGC arc tangent function demodulation algorithm. The simulation and analysis are also carried on. According to the analysis of demodulation speed and precision, the simulation of different numbers of sampling points, and measurement results of the pressure sensor, the arc tangent function demodulation method has good demodulation results: 1 MHz processing speed of single data and less than 1% error showing practical feasibility in the fiber-optic Fabry-Perot cavity length demodulation of the Fabry-Perot high-temperature pressure sensor.

Optical and x-ray characterization of two novel CMOS image sensors

NASA Astrophysics Data System (ADS)

Bohndiek, Sarah E.; Arvanitis, Costas D.; Venanzi, Cristian; Royle, Gary J.; Clark, Andy T.; Crooks, Jamie P.; Prydderch, Mark L.; Turchetta, Renato; Blue, Andrew; Speller, Robert D.

2007-02-01

A UK consortium (MI3) has been founded to develop advanced CMOS pixel designs for scientific applications. Vanilla, a 520x520 array of 25μm pixels benefits from flushed reset circuitry for low noise and random pixel access for region of interest (ROI) readout. OPIC, a 64x72 test structure array of 30μm digital pixels has thresholding capabilities for sparse readout at 3,700fps. Characterization is performed with both optical illumination and x-ray exposure via a scintillator. Vanilla exhibits 34+/-3e - read noise, interactive quantum efficiency of 54% at 500nm and can read a 6x6 ROI at 24,395fps. OPIC has 46+/-3e - read noise and a wide dynamic range of 65dB due to high full well capacity. Based on these characterization studies, Vanilla could be utilized in applications where demands include high spectral response and high speed region of interest readout while OPIC could be used for high speed, high dynamic range imaging.

The dynamic behavior of microbubbles during long ultrasound tone-burst excitation: mechanistic insights into ultrasound-microbubble mediated therapeutics using high-speed imaging and cavitation detection

PubMed Central

Pacella, John J.; Villanueva, Flordeliza S.

2015-01-01

Ultrasound (US)-microbubble (MB) mediated therapies have been shown to restore perfusion and enhance drug/gene delivery. Due to the presumption that MBs do not persist during long US exposure under high acoustic pressures, most schemes utilize short US pulses when a high US pressure is employed. However, we recently observed an enhanced thrombolytic effect using long US pulses at high acoustic pressures. Therefore we explored the fate of MBs during long tone-burst exposures (5 ms) at various acoustic pressures and MB concentrations via direct high-speed optical observation and passive cavitation detection. MBs first underwent stable or inertial cavitation depending on the acoustic pressure, and then formed gas-filled clusters that continued to oscillate, break up, and form new clusters. Cavitation detection confirmed continued, albeit diminishing acoustic activity throughout the 5-ms US excitation. These data suggest that persisting cavitation activity during long tone-bursts may confer additional therapeutic effects. PMID:26603628

NASA information sciences and human factors program

NASA Technical Reports Server (NTRS)

1991-01-01

The Data Systems Program consists of research and technology devoted to controlling, processing, storing, manipulating, and analyzing space-derived data. The objectives of the program are to provide the technology advancements needed to enable affordable utilization of space-derived data, to increase substantially the capability for future missions of on-board processing and recording and to provide high-speed, high-volume computational systems that are anticipated for missions such as the evolutionary Space Station and Earth Observing System.

Molecular filter-based diagnostics in high speed flows

NASA Technical Reports Server (NTRS)

Elliott, Gregory S.; Samimy, MO; Arnette, Stephen A.

1993-01-01

The use of iodine molecular filters in nonintrusive planar velocimetry methods is examined. Detailed absorption profiles are obtained to highlight the effects that determine the profile shape. It is shown that pressure broadening induced by the presence of a nonabsorbing vapor can be utilized to significantly change the slopes bounding the absorbing region while remaining in the optically-thick regime.

Improved Engine Performance and Efficiency Utilizing a Superturbocharger

DTIC Science & Technology

2012-08-01

supercharger, turbocharger and turbo-compounder in one single device. This is accomplished by mechanically controlling the speed ratio between the...the engine. This is made possible by a high efficiency turbine wheel. Normal turbochargers must balance the turbine power against the compressor...SuperTurbocharger and compare it against the currently used turbocharger in military vehicles to evaluate the impact on performance and efficiency

Low Noise Mid-Wavelength IR Photodetectors

DTIC Science & Technology

2014-02-19

Theoretical Framework and Calculated Results We will first review the theoretical limit for single-stage photovoltaic (PV) detectors and then proceed...efficient the device utilizes the incident photons. We see that Eq. 12 reduces to the standard expression for a single-absorber photovoltaic detector...mid-IR spectrum, one can expect growing demands and applications for high-speed detectors that operate at thermoelectric cooler temperatures with

RQL Fuel Shifting Sector Rig Test

NASA Technical Reports Server (NTRS)

Holdeman, James D. (Technical Monitor); Haid, Daniel A.; Koopman, Frederick S.; Peschke, William O. T.; Siskind, Kenneth S.

2004-01-01

The low emissions potential of a Rich-Quench-Lean (RQL) combustor for use in the HIgh Speed Civil transport (HSCT) application was evaluated as part of the NASA Critical Propulsion Components (CPC) Program. Fuel shifting as an approach to combustor control was evaluated in a multiple bank RQL combustor, utilizing reduced scale quench technology implemented in a convoluted linear with quench plate concept.

Concept development of a Mach 4 high-speed civil transport

NASA Technical Reports Server (NTRS)

Domack, Christopher S.; Dollyhigh, Samuel M.; Beissner, Fred L., Jr.; Geiselhart, Karl A.; Mcgraw, Marvin E., Jr.; Shields, Elwood W.; Swanson, Edward E.

1990-01-01

A study was conducted to configure and analyze a 250 passenger, Mach 4 High Speed Civil Transport with a design range of 6500 n.mi. The design mission assumed an all-supersonic cruise segment and no community noise or sonic boom constraints. The study airplane was developed in order to examine the technology requirements for such a vehicle and to provide an unconstrained baseline from which to assess changes in technology levels, sonic boom limits, or community noise constraints in future studies. The propulsion, structure, and materials technologies utilized in the sizing of the study aircraft were assumed to represent a technology availability date of 2015. The study airplane was a derivative of a previously developed Mach 3 concept and utilized advanced afterburning turbojet engines and passive airframe thermal protection. Details of the configuration development, aerodynamic design, propulsion system, mass properties, and mission performance are presented. The study airplane was estimated to weigh approx. 866,000 lbs. Although an aircraft of this size is a marginally acceptable candidate to fit into the world airport infrastructure, it was concluded that the inclusion of community noise or sonic boom constraints would quickly cause the aircraft to grow beyond acceptable limits using the assumed technology levels.

A composite model for a class of electric-discharge shock tubes

NASA Technical Reports Server (NTRS)

Elkins, R. T.; Baganoff, D.

1973-01-01

A gasdynamic model is presented and analyzed for a class of shock tubes that utilize both Joule heating and electromagnetic forces to produce high-speed shock waves. The model consists of several stages of acceleration in which acceleration to sonic conditions is achieved principally through heating, and further acceleration of the supersonic flow is obtained principally through use of electromagnetic forces. The utility of the model results from the fact that it predicts a quasi-steady flow process, mathematical analysis is straightforward, and it is even possible to remove one or more component stages and still have the model related to a possible shock-tube flow. Initial experiments have been performed where the electrical discharge configuration and current level were such that Joule heating was the dominant form of energy addition present. These experiments indicate that the predictions of the model dealing with heat addition correspond quite closely to reality. The experimental data together with the theory show that heat addition to the flowing driver gas after diaphragm rupture (approach used in the model) is much more effective in producing high-speed shock waves than heating the gas in the driver before diaphragm rupture, as in the case of the arc-driven shock tube.

14 CFR 23.233 - Directional stability and control.

Code of Federal Regulations, 2012 CFR

2012-01-01

... landings at normal landing speed, without using brakes or engine power to maintain a straight path until the speed has decreased to at least 50 percent of the speed at touchdown. (c) The airplane must have... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Ground...

14 CFR 23.233 - Directional stability and control.

Code of Federal Regulations, 2010 CFR

2010-01-01

... landings at normal landing speed, without using brakes or engine power to maintain a straight path until the speed has decreased to at least 50 percent of the speed at touchdown. (c) The airplane must have... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Ground...

14 CFR 23.233 - Directional stability and control.

Code of Federal Regulations, 2014 CFR

2014-01-01

... landings at normal landing speed, without using brakes or engine power to maintain a straight path until the speed has decreased to at least 50 percent of the speed at touchdown. (c) The airplane must have... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Ground...

14 CFR 23.233 - Directional stability and control.

Code of Federal Regulations, 2013 CFR

2013-01-01

... landings at normal landing speed, without using brakes or engine power to maintain a straight path until the speed has decreased to at least 50 percent of the speed at touchdown. (c) The airplane must have... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Ground...

14 CFR 23.233 - Directional stability and control.

Code of Federal Regulations, 2011 CFR

2011-01-01

... landings at normal landing speed, without using brakes or engine power to maintain a straight path until the speed has decreased to at least 50 percent of the speed at touchdown. (c) The airplane must have... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Ground...

32 CFR 636.22 - Speed regulations.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... (b) Drivers will operate their vehicles at a reasonable and prudent speed based on traffic and road... drivers will obey posted speed limits; however, drivers will not exceed 40 miles per hour on paved roads and 25 miles per hour on unpaved roads and tank trails. Commercial Utility Cargo Vehicles (CUCV's) are...

32 CFR 636.22 - Speed regulations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... operate their vehicles at a reasonable and prudent speed based on traffic and road conditions, regardless... obey posted speed limits; however, drivers will not exceed 40 miles per hour on paved roads and 25 miles per hour on unpaved roads and tank trails. Commercial Utility Cargo Vehicles (CUCV's) are tactical...

Prospects for utilization of air liquefaction and enrichment system (ALES) propulsion in fully reusable launch vehicles

NASA Technical Reports Server (NTRS)

Bond, W. H.; Yi, A. C.

1993-01-01

A concept is shown for a fully reusable, earth to orbit launch vehicle with horizontal takeoff and landing, employing an air-turborocket for low speed and a rocket for high speed acceleration, both using LH2 fuel. The turborocket employs a modified liquid air cycle to supply the oxidizer. The rocket uses 90 percent pure LOX that is collected from the atmosphere, separated, and stored during operation of the turborocket from about Mach 2 to Mach 5 or 6. The takeoff weight and the thrust required at takeoff are markedly reduced by collecting the rocket oxidizer in-flight. The paper shows an approach and the corresponding technology needs for using ALES propulsion in a SSTO vehicle. Reducing the trajectory altitude at the end of collection reduces the wing area and increases payload. The use of state-of-the-art materials, such as graphite polyimide, is critical to meet the structure weight objective for SSTO. Configurations that utilize 'waverider' aerodynamics show great promise to reduce the vehicle weight.

Parametrics for Molecular Deuterium Concentrations in the Source Region of the UW-IEC Device Using an Ion Acoustic Wave Diagnostic

NASA Astrophysics Data System (ADS)

Boris, D. R.; Emmert, G. A.

2007-11-01

The ion source region of the UW-Inertial Electrostatic Confinement device is comprised of a filament assisted DC discharge plasma that exists between the wall of the IEC vacuum chamber and the grounded spherical steel grid that makes up the anode of the IEC device. A 0-dimensional rate equation calculation of the molecular deuterium ion species concentration has been applied utilizing varying primary electron energy, and neutral gas pressure. By propagating ion acoustic waves in the source region of the IEC device the concentrations of molecular deuterium ion species have been determined for these varying plasma conditions, and high D3^+ concentrations have been verified. This was done by utilizing the multi-species ion acoustic wave dispersion relation, which relates the phase speed of the multi-species ion acoustic wave, vph, to the sum in quadrature of the concentration weighted ion acoustic sound speeds of the individual ion species.

A Survey on Next-generation Power Grid Data Architecture

DOE Office of Scientific and Technical Information (OSTI.GOV)

You, Shutang; Zhu, Dr. Lin; Liu, Yong

2015-01-01

The operation and control of power grids will increasingly rely on data. A high-speed, reliable, flexible and secure data architecture is the prerequisite of the next-generation power grid. This paper summarizes the challenges in collecting and utilizing power grid data, and then provides reference data architecture for future power grids. Based on the data architecture deployment, related research on data architecture is reviewed and summarized in several categories including data measurement/actuation, data transmission, data service layer, data utilization, as well as two cross-cutting issues, interoperability and cyber security. Research gaps and future work are also presented.

Efficient hiding of confidential high-utility itemsets with minimal side effects

NASA Astrophysics Data System (ADS)

Lin, Jerry Chun-Wei; Hong, Tzung-Pei; Fournier-Viger, Philippe; Liu, Qiankun; Wong, Jia-Wei; Zhan, Justin

2017-11-01

Privacy preserving data mining (PPDM) is an emerging research problem that has become critical in the last decades. PPDM consists of hiding sensitive information to ensure that it cannot be discovered by data mining algorithms. Several PPDM algorithms have been developed. Most of them are designed for hiding sensitive frequent itemsets or association rules. Hiding sensitive information in a database can have several side effects such as hiding other non-sensitive information and introducing redundant information. Finding the set of itemsets or transactions to be sanitised that minimises side effects is an NP-hard problem. In this paper, a genetic algorithm (GA) using transaction deletion is designed to hide sensitive high-utility itemsets for PPUM. A flexible fitness function with three adjustable weights is used to evaluate the goodness of each chromosome for hiding sensitive high-utility itemsets. To speed up the evolution process, the pre-large concept is adopted in the designed algorithm. It reduces the number of database scans required for verifying the goodness of an evaluated chromosome. Substantial experiments are conducted to compare the performance of the designed GA approach (with/without the pre-large concept), with a GA-based approach relying on transaction insertion and a non-evolutionary algorithm, in terms of execution time, side effects, database integrity and utility integrity. Results demonstrate that the proposed algorithm hides sensitive high-utility itemsets with fewer side effects than previous studies, while preserving high database and utility integrity.

The Attentional Demand of Automobile Driving Revisited: Occlusion Distance as a Function of Task-Relevant Event Density in Realistic Driving Scenarios.

PubMed

Kujala, Tuomo; Mäkelä, Jakke; Kotilainen, Ilkka; Tokkonen, Timo

2016-02-01

We studied the utility of occlusion distance as a function of task-relevant event density in realistic traffic scenarios with self-controlled speed. The visual occlusion technique is an established method for assessing visual demands of driving. However, occlusion time is not a highly informative measure of environmental task-relevant event density in self-paced driving scenarios because it partials out the effects of changes in driving speed. Self-determined occlusion times and distances of 97 drivers with varying backgrounds were analyzed in driving scenarios simulating real Finnish suburban and highway traffic environments with self-determined vehicle speed. Occlusion distances varied systematically with the expected environmental demands of the manipulated driving scenarios whereas the distributions of occlusion times remained more static across the scenarios. Systematic individual differences in the preferred occlusion distances were observed. More experienced drivers achieved better lane-keeping accuracy than inexperienced drivers with similar occlusion distances; however, driving experience was unexpectedly not a major factor for the preferred occlusion distances. Occlusion distance seems to be an informative measure for assessing task-relevant event density in realistic traffic scenarios with self-controlled speed. Occlusion time measures the visual demand of driving as the task-relevant event rate in time intervals, whereas occlusion distance measures the experienced task-relevant event density in distance intervals. The findings can be utilized in context-aware distraction mitigation systems, human-automated vehicle interaction, road speed prediction and design, as well as in the testing of visual in-vehicle tasks for inappropriate in-vehicle glancing behaviors in any dynamic traffic scenario for which appropriate individual occlusion distances can be defined. © 2015, Human Factors and Ergonomics Society.

Analysis of the electrical harmonic characteristics of a slip recovery variable speed generating system for wind turbine applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herrera, J.I.; Reddoch, T.W.

1988-02-01

Variable speed electric generating technology can enhance the general use of wind energy in electric utility applications. This enhancement results from two characteristic properties of variable speed wind turbine generators: an improvement in drive train damping characteristics, which results in reduced structural loading on the entire wind turbine system, and an improvement in the overall efficiency by using a more sophisticated electrical generator. Electronic converter systems are the focus of this investigation -- in particular, the properties of a wound-rotor induction generator with the slip recovery system and direct-current link converter. Experience with solid-state converter systems in large wind turbinesmore » is extremely limited. This report presents measurements of electrical performances of the slip recovery system and is limited to the terminal characteristics of the system. Variable speed generating systems working effectively in utility applications will require a satisfactory interface between the turbine/generator pair and the utility network. The electrical testing described herein focuses largely on the interface characteristics of the generating system. A MOD-O wind turbine was connected to a very strong system; thus, the voltage distortion was low and the total harmonic distortion in the utility voltage was less than 3% (within the 5% limit required by most utilities). The largest voltage component of a frequency below 60 Hz was 40 dB down from the 60-Hz< component. 8 refs., 14 figs., 8 tabs.« less

Implementation of a Non-Metallic Barrier in an Electric Motor

NASA Technical Reports Server (NTRS)

M?Sadoques, George; Carra, Michael; Beringer, Woody

2012-01-01

Electric motors that run in pure oxygen must be sealed, or "canned," for safety reasons to prevent the oxygen from entering into the electrical portion of the motor. The current canning process involves designing a metallic barrier around the rotor to provide the separation. This metallic barrier reduces the motor efficiency as speed is increased. In higher-speed electric motors, efficiency is greatly improved if a very thin, nonmetallic barrier can be utilized. The barrier thickness needs to be approximately 0.025-in. (.0.6-mm) thick and can be made of a brittle material such as glass. The motors, however, designed for space applications are typically subject to high-vibration environments. A fragile, non-metallic barrier can be utilized in a motor assembly if held in place by a set of standard rubber O-ring seals. The O-rings provide the necessary sealing to keep oxygen away from the electrical portion of the motor and also isolate the fragile barrier from the harsh motor vibration environment. The compliance of the rubber O-rings gently constrains the fragile barrier and isolates it from the harsh external motor environment. The use of a non-metallic barrier greatly improves motor performance, especially at higher speeds, while isolating the electronics from the working fluid with an inert liner.

Combined approach of shell and shear-warp rendering for efficient volume visualization

NASA Astrophysics Data System (ADS)

Falcao, Alexandre X.; Rocha, Leonardo M.; Udupa, Jayaram K.

2003-05-01

In Medical Imaging, shell rendering (SR) and shear-warp rendering (SWR) are two ultra-fast and effective methods for volume visualization. We have previously shown that, typically, SWR can be on the average 1.38 times faster than SR, but it requires from 2 to 8 times more memory space than SR. In this paper, we propose an extension of the compact shell data structure utilized in SR to allow shear-warp factorization of the viewing matrix in order to obtain speed up gains for SR, without paying the high storage price of SWR. The new approach is called shear-warp shell rendering (SWSR). The paper describes the methods, points out their major differences in the computational aspects, and presents a comparative analysis of them in terms of speed, storage, and image quality. The experiments involve hard and fuzzy boundaries of 10 different objects of various sizes, shapes, and topologies, rendered on a 1GHz Pentium-III PC with 512MB RAM, utilizing surface and volume rendering strategies. The results indicate that SWSR offers the best speed and storage characteristics compromise among these methods. We also show that SWSR improves the rendition quality over SR, and provides renditions similar to those produced by SWR.

Method of multi-mode vibration control for the carbody of high-speed electric multiple unit trains

NASA Astrophysics Data System (ADS)

Gong, Dao; Zhou, Jinsong; Sun, Wenjing; Sun, Yu; Xia, Zhanghui

2017-11-01

A method of multi-mode vibration control for the carbody of high-speed electric multiple unit (EMU) trains by using the onboard and suspended equipments as dynamic vibration absorbers (DVAs) is proposed. The effect of the multi-mode vibration on the ride quality of a high-speed EMU train was studied, and the target modes of vibration control were determined. An equivalent mass identification method was used to determine the equivalent mass for the target modes at the device installation positions. To optimize the vibration acceleration response of the carbody, the natural frequencies and damping ratios of the lateral and vertical vibration were designed based on the theory of dynamic vibration absorption. In order to realize the optimized design values of the natural frequencies for the lateral and vertical vibrations simultaneously, a new type of vibration absorber was designed in which a belleville spring and conventional rubber parts are connected in parallel. This design utilizes the negative stiffness of the belleville spring. Results show that, as compared to rigid equipment connections, the proposed method effectively reduces the multi-mode vibration of a carbody in a high-speed EMU train, thereby achieving the control objectives. The ride quality in terms of the lateral and vertical vibration of the carbody is considerably improved. Moreover, the optimal value of the damping ratio is effective in dissipating the vibration energy, which reduces the vibration of both the carbody and the equipment.

Magnetic bearings for inertial energy storage

NASA Technical Reports Server (NTRS)

Rodriguez, G. Ernest; Eakin, Vickie

1987-01-01

Advanced flywheels utilizing high strength fibers must operate at high rotational speeds and as such must operate in vacuum to reduce windage losses. The utilization of magnetic bearings in the flywheels overcome lubrication and seal problems, resulting in an energy storage system offering potential improvements over conventional electrochemical energy storage. Magnetic bearings evolved in the 1950s from the simple application of permanent magnets positioned to exert repulsive forces to the present where permanent magnets and electromagnets have been combined to provide axial and radial suspension. Further development of magnetic suspension has led to the design of a shaftless flywheel system for aerospace application. Despite the lack of proof of concept, integrated magnetic suspension in inertial storage systems can provide significant performance improvements to warrant development and tests.

Spin wave nonreciprocity for logic device applications

NASA Astrophysics Data System (ADS)

Jamali, Mahdi; Kwon, Jae Hyun; Seo, Soo-Man; Lee, Kyung-Jin; Yang, Hyunsoo

2013-11-01

The utilization of spin waves as eigenmodes of the magnetization dynamics for information processing and communication has been widely explored recently due to its high operational speed with low power consumption and possible applications for quantum computations. Previous proposals of spin wave Mach-Zehnder devices were based on the spin wave phase, a delicate entity which can be easily disrupted. Here, we propose a complete logic system based on the spin wave amplitude utilizing the nonreciprocal spin wave behavior excited by microstrip antennas. The experimental data reveal that the nonreciprocity of magnetostatic surface spin wave can be tuned by the bias magnetic field. Furthermore, engineering of the device structure could result in a high nonreciprocity factor for spin wave logic applications.

Advanced Engine Health Management Applications of the SSME Real-Time Vibration Monitoring System

NASA Technical Reports Server (NTRS)

Fiorucci, Tony R.; Lakin, David R., II; Reynolds, Tracy D.; Turner, James E. (Technical Monitor)

2000-01-01

The Real Time Vibration Monitoring System (RTVMS) is a 32-channel high speed vibration data acquisition and processing system developed at Marshall Space Flight Center (MSFC). It Delivers sample rates as high as 51,200 samples/second per channel and performs Fast Fourier Transform (FFT) processing via on-board digital signal processing (DSP) chips in a real-time format. Advanced engine health assessment is achieved by utilizing the vibration spectra to provide accurate sensor validation and enhanced engine vibration redlines. Discrete spectral signatures (such as synchronous) that are indicators of imminent failure can be assessed and utilized to mitigate catastrophic engine failures- a first in rocket engine health assessment. This paper is presented in viewgraph form.

Spin wave nonreciprocity for logic device applications

PubMed Central

Jamali, Mahdi; Kwon, Jae Hyun; Seo, Soo-Man; Lee, Kyung-Jin; Yang, Hyunsoo

2013-01-01

The utilization of spin waves as eigenmodes of the magnetization dynamics for information processing and communication has been widely explored recently due to its high operational speed with low power consumption and possible applications for quantum computations. Previous proposals of spin wave Mach-Zehnder devices were based on the spin wave phase, a delicate entity which can be easily disrupted. Here, we propose a complete logic system based on the spin wave amplitude utilizing the nonreciprocal spin wave behavior excited by microstrip antennas. The experimental data reveal that the nonreciprocity of magnetostatic surface spin wave can be tuned by the bias magnetic field. Furthermore, engineering of the device structure could result in a high nonreciprocity factor for spin wave logic applications. PMID:24196318

Modeling Co-Extruded Cathodes for High Energy Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cobb, Corie Lynn

2016-06-01

Utilizing an existing macro-homogeneous porous electrode model developed by John Newman, this talk presents the potential energy density gains that can be realized in lithium-ion battery electrodes fabricated with co-extrusion (CoEx) technology. CoEx uses carefully engineered fluidic channels to cause multiple streams of dissimilar fluids to impart shape to one another. The result is a high-speed, continuous deposition process that can create fine linear structures much smaller than the smallest physical feature within the printhead. By eliminating the small channels necessary for conventional extrusion and injection processes, CoEx is able to deposit highly loaded and viscous pastes at high linemore » speeds under reasonable operating pressures. The CoEx process is capable of direct deposition of features as small as 10 μm with aspect ratios of 5 or greater, and print speeds > 80 ft/min. We conduct an analysis on two-dimensional cathode cross-sections in COMSOL and present the electrochemical performance results, including calculated volumetric energy capacity for Lithium Nickel Manganese Cobalt Oxide (NMC) co-extruded cathodes, in the presence of a lithium metal anode, polymer separator and ethylene carbonate–diethyl carbonate (EC:DEC) liquid electrolyte. The impact of structured electrodes on cell performance is investigated by varying the physical distribution of a fixed amount of cathode mass over a space of dimensions which can be fabricated by CoEx. By systematically varying the thickness and aspect ratio of the electrode structures, we present an optimal subset of geometries and design rules for co-extruded geometries. Modeling results demonstrate that NMC CoEx cathodes, on the order of 125-200 µm thick, can garner an improvement in material utilization and in turn capacity through the addition of fine width electrolyte channels or highly conductive electrode regions. We also present initial experimental results on CoEx NMC cathode structures.« less

On-line miniaturized asymmetrical flow field-flow fractionation-electrospray ionization-tandem mass spectrometry with selected reaction monitoring for quantitative analysis of phospholipids in plasma lipoproteins.

PubMed

Yang, Iseul; Kim, Ki Hun; Lee, Ju Yong; Moon, Myeong Hee

2014-01-10

A direct analytical method for high speed quantitative analysis of lipids in human blood plasma using on-line chip-type asymmetrical flow field-flow fractionation-electrospray ionization-tandem mass spectrometry (cAF4-ESI-MS/MS) with selected reaction monitoring (SRM) is described in this study. Utilizing a miniaturized cAF4 channel, high speed size separation of high density lipoproteins (HDL) and low density lipoproteins (LDL) from plasma samples can be accomplished at a microflow rate along with simultaneous desalting of lipoproteins, both of which are conducive to direct ESI of lipids in lipoproteins. This study demonstrates that the SRM method to monitor phospholipids during cAF4-ESI-MS/MS can be successfully applied to the quantitation of lipid molecules in plasma lipoproteins without the need of a separate lipid extraction process. For quantitation of lipids in HDL and LDL during cAF4-ESI-MS/MS runs, a protein standard (carbonic anhydrase, 29 kDa) was added to each plasma sample as an internal standard such that a peak intensity of y67(+5) ions, which are high abundant SRM product ions of CA, could be utilized to calculate the relative intensity of each lipid molecule. The developed method was applied to plasma samples from 10 patients with coronary artery disease (CAD) and 10 healthy control samples, and quantitative analysis of 39 lipid molecules including phosphatidylcholines, phosphatidylethanolamines, sphingomyelins, phosphatidylglycerols, and phosphatidylinositols, resulted in the selection of 13 PL species showing more than 2.5 fold difference in relative abundance (p<0.01) between the groups. The present study demonstrates a high speed analytical method for determining plasma lipid content and distribution without an organic solvent extraction of lipids from plasma. Copyright © 2013 Elsevier B.V. All rights reserved.

High-speed broadband nanomechanical property quantification and imaging of life science materials using atomic force microscope

NASA Astrophysics Data System (ADS)

Ren, Juan

Nanoscale morphological characterization and mechanical properties quantification of soft and biological materials play an important role in areas ranging from nano-composite material synthesis and characterization, cellular mechanics to drug design. Frontier studies in these areas demand the coordination between nanoscale morphological evolution and mechanical behavior variations through simultaneous measurement of these two aspects of properties. Atomic force microscope (AFM) is very promising in achieving such simultaneous measurements at high-speed and broadband owing to its unique capability in applying force stimuli and then, measuring the response at specific locations in a physiologically friendly environment with pico-newton force and nanometer spatial resolution. Challenges, however, arise as current AFM systems are unable to account for the complex and coupled dynamics of the measurement system and probe-sample interaction during high-speed imaging and broadband measurements. In this dissertation, the creation of a set of dynamics and control tools to probe-based high-speed imaging and rapid broadband nanomechanical spectroscopy of soft and biological materials are presented. Firstly, advanced control-based approaches are presented to improve the imaging performance of AFM imaging both in air and in liquid. An adaptive contact mode (ACM) imaging scheme is proposed to replace the traditional contact mode (CM) imaging by addressing the major concerns in both the speed and the force exerted to the sample. In this work, the image distortion caused by the topography tracking error is accounted for in the topography quantification and the quantified sample topography is utilized in a gradient-based optimization method to adjust the cantilever deflection set-point for each scanline closely around the minimal level needed for maintaining a stable probe-sample contact, and a data-driven iterative feedforward control that utilizes a prediction of the next-line tracking is implemented to enhance the sample topography tracking. An adaptive multi-loop mode (AMLM) imaging approach is proposed to substantially increase the imaging speed of tapping mode (TM) while preserving the advantages of TM over CM by integrating an inner-outer feedback control loop to regulate the TM-deflection on top of the conventional TM-amplitude feedback control to improve the sample topography tracking. Experiments demonstrated that the proposed ACM and AMLM are capable of increasing the imaging speed by at least 20 times for conventional contact and tapping mode imaging, respectively, with no loss of imaging quality and well controlled tip-sample interaction force. In addition, an adaptive mode imaging for in-liquid topography quantification on live cells is presented. The experiment results demonstrated that instead of keeping constant scanning speed, the proposed speed optimization scheme is able to increase the imaging speed on live human prostate cancer cells by at least eight-fold with no loss of imaging quality. Secondly, control based approaches to accurate nanomechanical quantification on soft materials for both broadband and in-liquid force-curve measurements are proposed to address the adverse effects caused by the system coupling dynamics and the cantilever acceleration, which were not compensated for by the conventional AFM measurement approach. The proposed nanomechanical measurement approaches are demonstrated through experiments to measure the viscoelastic properties of different polymer samples in air and live human cells in liquid to study the variation of rate-dependent elastic modulus of cervix cancer cell during the epithelial-mesenchymal transition process.

Photogrammetry System and Method for Determining Relative Motion Between Two Bodies

NASA Technical Reports Server (NTRS)

Miller, Samuel A. (Inventor); Severance, Kurt (Inventor)

2014-01-01

A photogrammetry system and method provide for determining the relative position between two objects. The system utilizes one or more imaging devices, such as high speed cameras, that are mounted on a first body, and three or more photogrammetry targets of a known location on a second body. The system and method can be utilized with cameras having fish-eye, hyperbolic, omnidirectional, or other lenses. The system and method do not require overlapping fields-of-view if two or more cameras are utilized. The system and method derive relative orientation by equally weighting information from an arbitrary number of heterogeneous cameras, all with non-overlapping fields-of-view. Furthermore, the system can make the measurements with arbitrary wide-angle lenses on the cameras.

Experimental investigation of the abrasive crown dynamics in orbital atherectomy.

PubMed

Zheng, Yihao; Belmont, Barry; Shih, Albert J

2016-07-01

Orbital atherectomy is a catheter-based minimally invasive procedure to modify the plaque within atherosclerotic arteries using a diamond abrasive crown. This study was designed to investigate the crown motion and its corresponding contact force with the vessel. To this end, a transparent arterial tissue-mimicking phantom made of polyvinyl chloride was developed, a high-speed camera and image processing technique were utilized to visualize and quantitatively analyze the crown motion in the vessel phantom, and a piezoelectric dynamometer measured the forces on the phantom during the procedure. Observed under typical orbital atherectomy rotational speeds of 60,000, 90,000, and 120,000rpm in a 4.8mm caliber vessel phantom, the crown motion was a combination of high-frequency rotation at 1000, 1500, and 1660.4-1866.1Hz and low-frequency orbiting at 18, 38, and 40Hz, respectively. The measured forces were also composed of these high and low frequencies, matching well with the rotation of the eccentric crown and the associated orbital motion. The average peak force ranged from 0.1 to 0.4N at different rotational speeds. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Photothermal nanoblade for patterned cell membrane cutting

PubMed Central

Wu, Ting-Hsiang; Teslaa, Tara; Teitell, Michael A.; Chiou, Pei-Yu

2010-01-01

We report a photothermal nanoblade that utilizes a metallic nanostructure to harvest short laser pulse energy and convert it into a highly localized and specifically shaped explosive vapor bubble. Rapid bubble expansion and collapse punctures a lightly-contacting cell membrane via high-speed fluidic flows and induced transient shear stress. The membrane cutting pattern is controlled by the metallic nanostructure configuration, laser pulse polarization, and energy. Highly controllable, sub-micron sized circular hole pairs to half moon-like, or cat-door shaped, membrane cuts were realized in glutaraldehyde treated HeLa cells. PMID:21164656

Numerical study on wake characteristics of high-speed trains

NASA Astrophysics Data System (ADS)

Yao, Shuan-Bao; Sun, Zhen-Xu; Guo, Di-Long; Chen, Da-Wei; Yang, Guo-Wei

2013-12-01

Intensive turbulence exists in the wakes of high speed trains, and the aerodynamic performance of the trailing car could deteriorate rapidly due to complicated features of the vortices in the wake zone. As a result, the safety and amenity of high speed trains would face a great challenge. This paper considers mainly the mechanism of vortex formation and evolution in the train flow field. A real CRH2 model is studied, with a leading car, a middle car and a trailing car included. Different running speeds and cross wind conditions are considered, and the approaches of unsteady Reynold-averaged Navier-Stokes (URANS) and detached eddy simulation (DES) are utilized, respectively. Results reveal that DES has better capability of capturing small eddies compared to URANS. However, for large eddies, the effects of two approaches are almost the same. In conditions without cross winds, two large vortex streets stretch from the train nose and interact strongly with each other in the wake zone. With the reinforcement of the ground, a complicated wake vortex system generates and becomes strengthened as the running speed increases. However, the locations of flow separations on the train surface and the separation mechanism keep unchanged. In conditions with cross winds, three large vortices develop along the leeward side of the train, among which the weakest one has no obvious influence on the wake flow while the other two stretch to the tail of the train and combine with the helical vortices in the train wake. Thus, optimization of the aerodynamic performance of the trailing car should be aiming at reducing the intensity of the wake vortex system.

Internal fluid mechanics research on supercomputers for aerospace propulsion systems

NASA Technical Reports Server (NTRS)

Miller, Brent A.; Anderson, Bernhard H.; Szuch, John R.

1988-01-01

The Internal Fluid Mechanics Division of the NASA Lewis Research Center is combining the key elements of computational fluid dynamics, aerothermodynamic experiments, and advanced computational technology to bring internal computational fluid mechanics (ICFM) to a state of practical application for aerospace propulsion systems. The strategies used to achieve this goal are to: (1) pursue an understanding of flow physics, surface heat transfer, and combustion via analysis and fundamental experiments, (2) incorporate improved understanding of these phenomena into verified 3-D CFD codes, and (3) utilize state-of-the-art computational technology to enhance experimental and CFD research. Presented is an overview of the ICFM program in high-speed propulsion, including work in inlets, turbomachinery, and chemical reacting flows. Ongoing efforts to integrate new computer technologies, such as parallel computing and artificial intelligence, into high-speed aeropropulsion research are described.

20-meter underwater wireless optical communication link with 1.5 Gbps data rate.

PubMed

Shen, Chao; Guo, Yujian; Oubei, Hassan M; Ng, Tien Khee; Liu, Guangyu; Park, Ki-Hong; Ho, Kang-Ting; Alouini, Mohamed-Slim; Ooi, Boon S

2016-10-31

The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (~10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 × 10^-5, and 3.0 × 10^-3, respectively, which pass well the forward error correction (FEC) criterion.

Variable Mach number design approach for a parallel waverider with a wide-speed range based on the osculating cone theory

NASA Astrophysics Data System (ADS)

Zhao, Zhen-tao; Huang, Wei; Li, Shi-Bin; Zhang, Tian-Tian; Yan, Li

2018-06-01

In the current study, a variable Mach number waverider design approach has been proposed based on the osculating cone theory. The design Mach number of the osculating cone constant Mach number waverider with the same volumetric efficiency of the osculating cone variable Mach number waverider has been determined by writing a program for calculating the volumetric efficiencies of waveriders. The CFD approach has been utilized to verify the effectiveness of the proposed approach. At the same time, through the comparative analysis of the aerodynamic performance, the performance advantage of the osculating cone variable Mach number waverider is studied. The obtained results show that the osculating cone variable Mach number waverider owns higher lift-to-drag ratio throughout the flight profile when compared with the osculating cone constant Mach number waverider, and it has superior low-speed aerodynamic performance while maintaining nearly the same high-speed aerodynamic performance.

Vehicle Signal Analysis Using Artificial Neural Networks for a Bridge Weigh-in-Motion System

PubMed Central

Kim, Sungkon; Lee, Jungwhee; Park, Min-Seok; Jo, Byung-Wan

2009-01-01

This paper describes the procedures for development of signal analysis algorithms using artificial neural networks for Bridge Weigh-in-Motion (B-WIM) systems. Through the analysis procedure, the extraction of information concerning heavy traffic vehicles such as weight, speed, and number of axles from the time domain strain data of the B-WIM system was attempted. As one of the several possible pattern recognition techniques, an Artificial Neural Network (ANN) was employed since it could effectively include dynamic effects and bridge-vehicle interactions. A number of vehicle traveling experiments with sufficient load cases were executed on two different types of bridges, a simply supported pre-stressed concrete girder bridge and a cable-stayed bridge. Different types of WIM systems such as high-speed WIM or low-speed WIM were also utilized during the experiments for cross-checking and to validate the performance of the developed algorithms. PMID:22408487

Vehicle Signal Analysis Using Artificial Neural Networks for a Bridge Weigh-in-Motion System.

PubMed

Kim, Sungkon; Lee, Jungwhee; Park, Min-Seok; Jo, Byung-Wan

2009-01-01

This paper describes the procedures for development of signal analysis algorithms using artificial neural networks for Bridge Weigh-in-Motion (B-WIM) systems. Through the analysis procedure, the extraction of information concerning heavy traffic vehicles such as weight, speed, and number of axles from the time domain strain data of the B-WIM system was attempted. As one of the several possible pattern recognition techniques, an Artificial Neural Network (ANN) was employed since it could effectively include dynamic effects and bridge-vehicle interactions. A number of vehicle traveling experiments with sufficient load cases were executed on two different types of bridges, a simply supported pre-stressed concrete girder bridge and a cable-stayed bridge. Different types of WIM systems such as high-speed WIM or low-speed WIM were also utilized during the experiments for cross-checking and to validate the performance of the developed algorithms.

Investigation of hit-and-run crash occurrence and severity using real-time loop detector data and hierarchical Bayesian binary logit model with random effects.

PubMed

Xie, Meiquan; Cheng, Wen; Gill, Gurdiljot Singh; Zhou, Jiao; Jia, Xudong; Choi, Simon

2018-02-17

Most of the extensive research dedicated to identifying the influential factors of hit-and-run (HR) crashes has utilized typical maximum likelihood estimation binary logit models, and none have employed real-time traffic data. To fill this gap, this study focused on investigating factors contributing to HR crashes, as well as the severity levels of HR. This study analyzed 4-year crash and real-time loop detector data by employing hierarchical Bayesian models with random effects within a sequential logit structure. In addition to evaluation of the impact of random effects on model fitness and complexity, the prediction capability of the models was examined. Stepwise incremental sensitivity and specificity were calculated and receiver operating characteristic (ROC) curves were utilized to graphically illustrate the predictive performance of the model. Among the real-time flow variables, the average occupancy and speed from the upstream detector were observed to be positively correlated with HR crash possibility. The average upstream speed and speed difference between upstream and downstream speeds were correlated with the occurrence of severe HR crashes. In addition to real-time factors, other variables found influential for HR and severe HR crashes were length of segment, adverse weather conditions, dark lighting conditions with malfunctioning street lights, driving under the influence of alcohol, width of inner shoulder, and nighttime. This study suggests the potential traffic conditions of HR and severe HR occurrence, which refer to relatively congested upstream traffic conditions with high upstream speed and significant speed deviations on long segments. The above findings suggest that traffic enforcement should be directed toward mitigating risky driving under the aforementioned traffic conditions. Moreover, enforcement agencies may employ alcohol checkpoints to counter driving under the influence (DUI) at night. With regard to engineering improvements, wider inner shoulders may be constructed to potentially reduce HR cases and street lights should be installed and maintained in working condition to make roads less prone to such crashes.

Sodium alginate hydrogel-based bioprinting using a novel multinozzle bioprinting system.

PubMed

Song, Seung-Joon; Choi, Jaesoon; Park, Yong-Doo; Hong, Soyoung; Lee, Jung Joo; Ahn, Chi Bum; Choi, Hyuk; Sun, Kyung

2011-11-01

Bioprinting is a technology for constructing bioartificial tissue or organs of complex three-dimensional (3-D) structure with high-precision spatial shape forming ability in larger scale than conventional tissue engineering methods and simultaneous multiple components composition ability. It utilizes computer-controlled 3-D printer mechanism or solid free-form fabrication technologies. In this study, sodium alginate hydrogel that can be utilized for large-dimension tissue fabrication with its fast gelation property was studied regarding material-specific printing technique and printing parameters using a multinozzle bioprinting system developed by the authors. A sodium alginate solution was prepared with a concentration of 1% (wt/vol), and 1% CaCl(2) solution was used as cross-linker for the gelation. The two materials were loaded in each of two nozzles in the multinozzle bioprinting system that has a total of four nozzles of which the injection speed can be independently controlled. A 3-D alginate structure was fabricated through layer-by-layer printing. Each layer was formed through two phases of printing, the first phase with the sodium alginate solution and the second phase with the calcium chloride solution, in identical printing pattern and speed condition. The target patterns were lattice shaped with 2-mm spacing and two different line widths. The nozzle moving speed was 6.67 mm/s, and the injection head speed was 10 µm/s. For the two different line widths, two injection needles with inner diameters of 260 and 410 µm were used. The number of layers accumulated was five in this experiment. By varying the nozzle moving speed and the injection speed, various pattern widths could be achieved. The feasibility of sodium alginate hydrogel free-form formation by alternate printing of alginate solution and sodium chloride solution was confirmed in the developed multinozzle bioprinting system. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Work zone speed reduction utilizing dynamic speed signs

DOT National Transportation Integrated Search

2011-08-30

Vast quantities of transportation data are automatically recorded by intelligent transportations infrastructure, such as inductive loop detectors, video cameras, and side-fire radar devices. Such devices are typically deployed by traffic management c...

Laminated helmet materials characterization by terahertz kinetics spectroscopy

NASA Astrophysics Data System (ADS)

Rahman, Anis; Rahman, Aunik K.

2015-05-01

High speed acquisition of reflected terahertz energy constitutes a kinetics spectrum that is an effective tool for layered materials' deformation characterization under ballistic impact. Here we describe utilizing the kinetics spectrum for quantifying a deformation event due to impact in material used for Soldier's helmet. The same technique may be utilized for real-time assessment of trauma by measuring the helmet wore by athletes. The deformation of a laminated material (e.g., a helmet) is dependent on the nature of impact and projectile; thus can uniquely characterize the impact condition leading to a diagnostic procedure based on the energy received by an athlete during an impact. We outline the calibration process for a given material under ballistic impact and then utilize the calibration for extracting physical parameters from the measured kinetics spectrum. Measured kinetics spectra are used to outline the method and rationale for extending the concept to a diagnosis tool. In particular, captured kinetics spectra from multilayered plates subjected to ballistic hit under experimental conditions by high speed digital acquisition system. An algorithm was devised to extract deformation and deformation velocity from which the energy received on the skull was estimated via laws of nonrelativistic motion. This energy is assumed to be related to actual injury conditions, thus forming a basis for determining whether the hit would cause concussion, trauma, or stigma. Such quantification may be used for diagnosing a Soldier's trauma condition in the field or that of an athlete's.

A computational approach to real-time image processing for serial time-encoded amplified microscopy

NASA Astrophysics Data System (ADS)

Oikawa, Minoru; Hiyama, Daisuke; Hirayama, Ryuji; Hasegawa, Satoki; Endo, Yutaka; Sugie, Takahisa; Tsumura, Norimichi; Kuroshima, Mai; Maki, Masanori; Okada, Genki; Lei, Cheng; Ozeki, Yasuyuki; Goda, Keisuke; Shimobaba, Tomoyoshi

2016-03-01

High-speed imaging is an indispensable technique, particularly for identifying or analyzing fast-moving objects. The serial time-encoded amplified microscopy (STEAM) technique was proposed to enable us to capture images with a frame rate 1,000 times faster than using conventional methods such as CCD (charge-coupled device) cameras. The application of this high-speed STEAM imaging technique to a real-time system, such as flow cytometry for a cell-sorting system, requires successively processing a large number of captured images with high throughput in real time. We are now developing a high-speed flow cytometer system including a STEAM camera. In this paper, we describe our approach to processing these large amounts of image data in real time. We use an analog-to-digital converter that has up to 7.0G samples/s and 8-bit resolution for capturing the output voltage signal that involves grayscale images from the STEAM camera. Therefore the direct data output from the STEAM camera generates 7.0G byte/s continuously. We provided a field-programmable gate array (FPGA) device as a digital signal pre-processor for image reconstruction and finding objects in a microfluidic channel with high data rates in real time. We also utilized graphics processing unit (GPU) devices for accelerating the calculation speed of identification of the reconstructed images. We built our prototype system, which including a STEAM camera, a FPGA device and a GPU device, and evaluated its performance in real-time identification of small particles (beads), as virtual biological cells, owing through a microfluidic channel.

Radiation-Tolerant Dual Data Bus

NASA Technical Reports Server (NTRS)

Kinstler, Gary A.

2007-01-01

An architecture, and a method of utilizing the architecture, have been proposed to enable error-free operation of a data bus that includes, and is connected to, commercial off-the-shelf (COTS) circuits and components that are inherently susceptible to singleevent upsets [SEUs (bit flips caused by impinging high-energy particles and photons)]. The architecture and method are applicable, more specifically, to data-bus circuitry based on the Institute for Electrical and Electronics Engineers (IEEE) 1394b standard for a high-speed serial bus.

Study for Air Vehicles at High Speeds, Identifying the Potential Benefits to Transport Aircraft of a Continuously Variable Geometry Trailing-Edge Structure that can be Utilized for Aircraft Control, Trim, Load-Alleviation, and High Lift

DTIC Science & Technology

2011-08-01

Field Length is defined as the total distance from brake release to the point at which the aircraft clears a height of 35 ft. The clearance height is...height clearance. The AEFL comprises two parts, the ground roll from brake release to lift-off (GR) plus the distance from lift-off to 35 ft height

Efficient dynamic optimization of logic programs

NASA Technical Reports Server (NTRS)

Laird, Phil

1992-01-01

A summary is given of the dynamic optimization approach to speed up learning for logic programs. The problem is to restructure a recursive program into an equivalent program whose expected performance is optimal for an unknown but fixed population of problem instances. We define the term 'optimal' relative to the source of input instances and sketch an algorithm that can come within a logarithmic factor of optimal with high probability. Finally, we show that finding high-utility unfolding operations (such as EBG) can be reduced to clause reordering.

RAMICS: trainable, high-speed and biologically relevant alignment of high-throughput sequencing reads to coding DNA.

PubMed

Wright, Imogen A; Travers, Simon A

2014-07-01

The challenge presented by high-throughput sequencing necessitates the development of novel tools for accurate alignment of reads to reference sequences. Current approaches focus on using heuristics to map reads quickly to large genomes, rather than generating highly accurate alignments in coding regions. Such approaches are, thus, unsuited for applications such as amplicon-based analysis and the realignment phase of exome sequencing and RNA-seq, where accurate and biologically relevant alignment of coding regions is critical. To facilitate such analyses, we have developed a novel tool, RAMICS, that is tailored to mapping large numbers of sequence reads to short lengths (<10 000 bp) of coding DNA. RAMICS utilizes profile hidden Markov models to discover the open reading frame of each sequence and aligns to the reference sequence in a biologically relevant manner, distinguishing between genuine codon-sized indels and frameshift mutations. This approach facilitates the generation of highly accurate alignments, accounting for the error biases of the sequencing machine used to generate reads, particularly at homopolymer regions. Performance improvements are gained through the use of graphics processing units, which increase the speed of mapping through parallelization. RAMICS substantially outperforms all other mapping approaches tested in terms of alignment quality while maintaining highly competitive speed performance. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Magnetic Bead Actuation of Saccular Hair Cells

NASA Astrophysics Data System (ADS)

Rowland, David; Ramunno-Johnson, Damien; Lee, Jae-Hyun; Cheon, Jinwoo; Bozovic, Dolores

2011-11-01

When decoupled from the overlying membrane, hair bundles of the amphibian sacculus exhibit spontaneous oscillation. To explore the dynamics of this innate motility without an imposed external load, we recorded their oscillations with a high-speed CMOS camera, and applied mechanical manipulation that minimally alters the geometry of an individual hair bundle. We present a technique that utilizes micron-sized magnetic particles to actuate the stereociliary bundle with a magnetized probe. Quasi-steady-state displacements were imposed on freely oscillating bundles. Our data indicate that deflection of the bundle affects both the frequency and the amplitude of the oscillations, with a crossing of the bifurcation that is dependent on the direction and speed of the applied offset.

Supersonic compressor

DOEpatents

Lawlor, Shawn P [Bellevue, WA; Novaresi, Mark A [San Diego, CA; Cornelius, Charles C [Kirkland, WA

2008-02-26

A gas compressor based on the use of a driven rotor having an axially oriented compression ramp traveling at a local supersonic inlet velocity (based on the combination of inlet gas velocity and tangential speed of the ramp) which forms a supersonic shockwave axially, between adjacent strakes. In using this method to compress inlet gas, the supersonic compressor efficiently achieves high compression ratios while utilizing a compact, stabilized gasdynamic flow path. Operated at supersonic speeds, the inlet stabilizes an oblique/normal shock system in the gasdyanamic flow path formed between the gas compression ramp on a strake, the shock capture lip on the adjacent strake, and captures the resultant pressure within the stationary external housing while providing a diffuser downstream of the compression ramp.

Graphene optical modulator

NASA Astrophysics Data System (ADS)

Liu, Ming; Yin, Xiaobo; Wang, Feng; Zhang, Xiang

2011-10-01

Data communications have been growing at a speed even faster than Moore's Law, with a 44-fold increase expected within the next 10 years. Data Transfer on such scale would have to recruit optical communication technology and inspire new designs of light sources, modulators, and photodetectors. An ideal optical modulator will require high modulation speed, small device footprint and large operating bandwidth. Silicon modulators based on free carrier plasma dispersion effect and compound semiconductors utilizing direct bandgap transition have seen rapid improvement over the past decade. One of the key limitations for using silicon as modulator material is its weak refractive index change, which limits the footprint of silicon Mach-Zehnder interferometer modulators to millimeters. Other approaches such as silicon microring modulators reduce the operation wavelength range to around 100 pm and are highly sensitive to typical fabrication tolerances and temperature fluctuations. Growing large, high quality wafers of compound semiconductors, and integrating them on silicon or other substrates is expensive, which also restricts their commercialization. In this work, we demonstrate that graphene can be used as the active media for electroabsorption modulators. By tuning the Fermi energy level of the graphene layer, we induced changes in the absorption coefficient of graphene at communication wavelength and achieve a modulation depth above 3 dB. This integrated device also has the potential of working at high speed.

Novel MDM-PON scheme utilizing self-homodyne detection for high-speed/capacity access networks.

PubMed

Chen, Yuanxiang; Li, Juhao; Zhu, Paikun; Wu, Zhongying; Zhou, Peng; Tian, Yu; Ren, Fang; Yu, Jinyi; Ge, Dawei; Chen, Jingbiao; He, Yongqi; Chen, Zhangyuan

2015-12-14

In this paper, we propose a cost-effective, energy-saving mode-division-multiplexing passive optical network (MDM-PON) scheme utilizing self-homodyne detection for high-speed/capacity access network based on low modal-crosstalk few-mode fiber (FMF) and all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). In the proposed scheme, one of the spatial modes is used to transmit a portion of signal carrier (namely pilot-tone) as the local oscillator (LO), while the others are used for signal-bearing channels. At the receiver, the pilot-tone and the signal can be separated without strong crosstalk and sent to the receiver for coherent detection. The spectral efficiency (SE) is significantly enhanced when multiple spatial channels are used. Meanwhile, the self-homodyne detection scheme can effectively suppress laser phase noise, which relaxes the requirement for the lasers line-width at the optical line terminal or optical network units (OLT/ONUs). The digital signal processing (DSP) at the receiver is also simplified since it removes the need for frequency offset compensation and complex phase correction, which reduces the computational complexity and energy consumption. Polarization division multiplexing (PDM) that offers doubled SE is also supported by the scheme. The proposed scheme is scalable to multi-wavelength application when wavelength MUX/DEMUX is utilized. Utilizing the proposed scheme, we demonstrate a proof of concept 4 × 40-Gb/s orthogonal frequency division multiplexing (OFDM) transmission over 55-km FMF using low modal-crosstalk two-mode FMF and MUX/DEMUX with error free operation. Compared with back to back case, less than 1-dB Q-factor penalty is observed after 55-km FMF of the four channels. Signal power and pilot-tone power are also optimized to achieve the optimal transmission performance.

Software Accelerates Computing Time for Complex Math

NASA Technical Reports Server (NTRS)

2014-01-01

Ames Research Center awarded Newark, Delaware-based EM Photonics Inc. SBIR funding to utilize graphic processing unit (GPU) technology- traditionally used for computer video games-to develop high-computing software called CULA. The software gives users the ability to run complex algorithms on personal computers with greater speed. As a result of the NASA collaboration, the number of employees at the company has increased 10 percent.

Analysis of Non-Tactical Vehicle Utilization at Fort Carson

DTIC Science & Technology

2012-03-30

regenerative braking energy recovery. The mass of the vehicles monitored in this study was not known. However, some useful information may be...regeneration to add braking action when the driver demand for deceleration rate exceeds the power absorption capability of the regenerative energy...recovery efficiency. However, the VSquareLoss calculation can be easily adapted to take into account the clipping of regenerative braking at high speeds

Cost-Effectiveness Analysis of Aerial Platforms and Suitable Communication Payloads

DTIC Science & Technology

2014-03-01

High altitude long endurance (HALE) platforms for tactical wireless communications and sensor use in military operations. (Master’s thesis, Naval...the ground, which can offer near limitless endurance. Additionally, running data over wired networks reduces wireless congestion. The most...system that utilizes different wind speeds and wind directions at different altitudes in an attempt to position the balloons for optimal communications

LMFBR with booster pump in pumping loop

DOEpatents

Rubinstein, H.J.

1975-10-14

A loop coolant circulation system is described for a liquid metal fast breeder reactor (LMFBR) utilizing a low head, high specific speed booster pump in the hot leg of the coolant loop with the main pump located in the cold leg of the loop, thereby providing the advantages of operating the main pump in the hot leg with the reliability of cold leg pump operation.

Ultralow-power all-optical processing of high-speed data signals in deposited silicon waveguides.

PubMed

Wang, Ke-Yao; Petrillo, Keith G; Foster, Mark A; Foster, Amy C

2012-10-22

Utilizing a 6-mm-long hydrogenated amorphous silicon nanowaveguide, we demonstrate error-free (BER < 10(-9)) 160-to-10 Gb/s OTDM demultiplexing using ultralow switching peak powers of 50 mW. This material is deposited at low temperatures enabling a path toward multilayer integration and therefore massive scaling of the number of devices in a single photonic chip.

High Speed Vortex Flows

NASA Technical Reports Server (NTRS)

Wood, Richard M.; Wilcox, Floyd J., Jr.; Bauer, Steven X. S.; Allen, Jerry M.

2000-01-01

A review of the research conducted at the National Aeronautics and Space Administration (NASA), Langley Research Center (LaRC) into high-speed vortex flows during the 1970s, 1980s, and 1990s is presented. The data reviewed is for flat plates, cavities, bodies, missiles, wings, and aircraft. These data are presented and discussed relative to the design of future vehicles. Also presented is a brief historical review of the extensive body of high-speed vortex flow research from the 1940s to the present in order to provide perspective of the NASA LaRC's high-speed research results. Data are presented which show the types of vortex structures which occur at supersonic speeds and the impact of these flow structures to vehicle performance and control is discussed. The data presented shows the presence of both small- and large scale vortex structures for a variety of vehicles, from missiles to transports. For cavities, the data show very complex multiple vortex structures exist at all combinations of cavity depth to length ratios and Mach number. The data for missiles show the existence of very strong interference effects between body and/or fin vortices and the downstream fins. It was shown that these vortex flow interference effects could be both positive and negative. Data are shown which highlights the effect that leading-edge sweep, leading-edge bluntness, wing thickness, location of maximum thickness, and camber has on the aerodynamics of and flow over delta wings. The observed flow fields for delta wings (i.e. separation bubble, classical vortex, vortex with shock, etc.) are discussed in the context of' aircraft design. And data have been shown that indicate that aerodynamic performance improvements are available by considering vortex flows as a primary design feature. Finally a discussing of a design approach for wings which utilize vortex flows for improved aerodynamic performance at supersonic speed is presented.

Experimental Evaluation of the High-Speed Motion Vector Measurement by Combining Synthetic Aperture Array Processing with Constrained Least Square Method

NASA Astrophysics Data System (ADS)

Yokoyama, Ryouta; Yagi, Shin-ichi; Tamura, Kiyoshi; Sato, Masakazu

2009-07-01

Ultrahigh speed dynamic elastography has promising potential capabilities in applying clinical diagnosis and therapy of living soft tissues. In order to realize the ultrahigh speed motion tracking at speeds of over thousand frames per second, synthetic aperture (SA) array signal processing technology must be introduced. Furthermore, the overall system performance should overcome the fine quantitative evaluation in accuracy and variance of echo phase changes distributed across a tissue medium. On spatial evaluation of local phase changes caused by pulsed excitation on a tissue phantom, investigation was made with the proposed SA signal system utilizing different virtual point sources that were generated by an array transducer to probe each component of local tissue displacement vectors. The final results derived from the cross-correlation method (CCM) brought about almost the same performance as obtained by the constrained least square method (LSM) extended to successive echo frames. These frames were reconstructed by SA processing after the real-time acquisition triggered by the pulsed irradiation from a point source. The continuous behavior of spatial motion vectors demonstrated the dynamic generation and traveling of the pulsed shear wave at a speed of one thousand frames per second.

The effects of the arm swing on biomechanical and physiological aspects of roller ski skating.

PubMed

Hegge, Ann Magdalen; Ettema, Gertjan; de Koning, Jos J; Rognstad, Asgeir Bakken; Hoset, Martin; Sandbakk, Øyvind

2014-08-01

This study analyzed the biomechanical and physiological effects of the arm swing in roller ski skating, and compared leg-skating (i.e. ski skating without poles) using a pronounced arm swing (SWING) with leg-skating using locked arms (LOCKED). Sixteen elite male cross-country skiers performed submaximal stages at 10, 15 and 20kmh(-1) on a 2% inclined treadmill in the two techniques. SWING demonstrated higher peak push-off forces and a higher force impulse at all speeds, but a longer cycle length only at the highest speed (all P<.05), indicating a lower force effectiveness with SWING at the two lowest speeds. Additionally, the flexion-extension movement in the lower limbs was more pronounced for SWING. Oxygen uptake was higher for SWING at the two lowest speeds (both P<.05) without any differences in blood lactate. At the highest speed, oxygen uptake did not differ between SWING and LOCKED, but the RER, blood lactate and ventilation were lower with SWING (all P<.05). Taken together, these results demonstrate that utilizing the arm swing in roller ski skating increases the ski forces and aerobic energy cost at low and moderate speeds, whereas the greater forces at high speed lead to a longer cycle length and smaller anaerobic contribution. Copyright © 2014 Elsevier B.V. All rights reserved.

A real-time 3D range image sensor based on a novel tip-tilt-piston micromirror and dual frequency phase shifting

NASA Astrophysics Data System (ADS)

Skotheim, Øystein; Schumann-Olsen, Henrik; Thorstensen, Jostein; Kim, Anna N.; Lacolle, Matthieu; Haugholt, Karl-Henrik; Bakke, Thor

2015-03-01

Structured light is a robust and accurate method for 3D range imaging in which one or more light patterns are projected onto the scene and observed with an off-axis camera. Commercial sensors typically utilize DMD- or LCD-based LED projectors, which produce good results but have a number of drawbacks, e.g. limited speed, limited depth of focus, large sensitivity to ambient light and somewhat low light efficiency. We present a 3D imaging system based on a laser light source and a novel tip-tilt-piston micro-mirror. Optical interference is utilized to create sinusoidal fringe patterns. The setup allows fast and easy control of both the frequency and the phase of the fringe patterns by altering the axes of the micro-mirror. For 3D reconstruction we have adapted a Dual Frequency Phase Shifting method which gives robust range measurements with sub-millimeter accuracy. The use of interference for generating sine patterns provides high light efficiency and good focusing properties. The use of a laser and a bandpass filter allows easy removal of ambient light. The fast response of the micro-mirror in combination with a high-speed camera and real-time processing on the GPU allows highly accurate 3D range image acquisition at video rates.

Comparison of two ways of altering carpal tunnel pressure with ultrasound surface wave elastography.

PubMed

Cheng, Yu-Shiuan; Zhou, Boran; Kubo, Kazutoshi; An, Kai-Nan; Moran, Steven L; Amadio, Peter C; Zhang, Xiaoming; Zhao, Chunfeng

2018-06-06

Higher carpal tunnel pressure is related to the development of carpal tunnel syndrome. Currently, the measurement of carpal tunnel pressure is invasive and therefore, a noninvasive technique is needed. We previously demonstrated that speed of wave propagation through a tendon in the carpal tunnel measured by ultrasound elastography could be used as an indicator of carpal tunnel pressure in a cadaveric model, in which a balloon had to be inserted into the carpal tunnel to adjust the carpal tunnel pressure. However, the method for adjusting the carpal tunnel pressure in the cadaveric model is not applicable for the in vivo model. The objective of this study was to utilize a different technique to adjust carpal tunnel pressure via pressing the palm and to validate it with ultrasound surface wave elastography in a human cadaveric model. The outcome was also compared with a previous balloon insertion technique. Results showed that wave speed of intra-carpal tunnel tendon and the ratio of wave speed of intra-and outer-carpal tunnel tendons increased linearly with carpal tunnel pressure. Moreover, wave speed of intra carpal tunnel tendon via both ways of altering carpal tunnel pressure showed similar results with high correlation. Therefore, it was concluded that the technique of pressing the palm can be used to adjust carpal tunnel pressure, and pressure changes can be detected via ultrasound surface wave elastography in an ex vivo model. Future studies will utilize this technique in vivo to validate the usefulness of ultrasound surface wave elastography for measuring carpal tunnel pressure. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fast grasping of unknown objects using principal component analysis

NASA Astrophysics Data System (ADS)

Lei, Qujiang; Chen, Guangming; Wisse, Martijn

2017-09-01

Fast grasping of unknown objects has crucial impact on the efficiency of robot manipulation especially subjected to unfamiliar environments. In order to accelerate grasping speed of unknown objects, principal component analysis is utilized to direct the grasping process. In particular, a single-view partial point cloud is constructed and grasp candidates are allocated along the principal axis. Force balance optimization is employed to analyze possible graspable areas. The obtained graspable area with the minimal resultant force is the best zone for the final grasping execution. It is shown that an unknown object can be more quickly grasped provided that the component analysis principle axis is determined using single-view partial point cloud. To cope with the grasp uncertainty, robot motion is assisted to obtain a new viewpoint. Virtual exploration and experimental tests are carried out to verify this fast gasping algorithm. Both simulation and experimental tests demonstrated excellent performances based on the results of grasping a series of unknown objects. To minimize the grasping uncertainty, the merits of the robot hardware with two 3D cameras can be utilized to suffice the partial point cloud. As a result of utilizing the robot hardware, the grasping reliance is highly enhanced. Therefore, this research demonstrates practical significance for increasing grasping speed and thus increasing robot efficiency under unpredictable environments.

Pilot tests of automated speed enforcement devices and procedures

DOT National Transportation Integrated Search

1984-02-01

This report concerns the identification of technologies applicable to speed enforcement and an assessment of their potential utility in the United States. The study emphasizes technologies in common use in Europe and elsewhere, but relatively unknown...

The science of computing - Parallel computation

NASA Technical Reports Server (NTRS)

Denning, P. J.

1985-01-01

Although parallel computation architectures have been known for computers since the 1920s, it was only in the 1970s that microelectronic components technologies advanced to the point where it became feasible to incorporate multiple processors in one machine. Concommitantly, the development of algorithms for parallel processing also lagged due to hardware limitations. The speed of computing with solid-state chips is limited by gate switching delays. The physical limit implies that a 1 Gflop operational speed is the maximum for sequential processors. A computer recently introduced features a 'hypercube' architecture with 128 processors connected in networks at 5, 6 or 7 points per grid, depending on the design choice. Its computing speed rivals that of supercomputers, but at a fraction of the cost. The added speed with less hardware is due to parallel processing, which utilizes algorithms representing different parts of an equation that can be broken into simpler statements and processed simultaneously. Present, highly developed computer languages like FORTRAN, PASCAL, COBOL, etc., rely on sequential instructions. Thus, increased emphasis will now be directed at parallel processing algorithms to exploit the new architectures.

MOD-2 wind turbine farm stability study

NASA Technical Reports Server (NTRS)

Hinrichsen, E. N.

1980-01-01

The dynamics of single and multiple 2.5 ME, Boeing MOD-2 wind turbine generators (WTGs) connected to utility power systems were investigated. The analysis was based on digital simulation. Both time response and frequency response methods were used. The dynamics of this type of WTG are characterized by two torsional modes, a low frequency 'shaft' mode below 1 Hz and an 'electrical' mode at 3-5 Hz. High turbine inertia and low torsional stiffness between turbine and generator are inherent features. Turbine control is based on electrical power, not turbine speed as in conventional utility turbine generators. Multi-machine dynamics differ very little from single machine dynamics.

Base drive circuit for a four-terminal power Darlington

DOEpatents

Lee, Fred C.; Carter, Roy A.

1983-01-01

A high power switching circuit which utilizes a four-terminal Darlington transistor block to improve switching speed, particularly in rapid turn-off. Two independent reverse drive currents are utilized during turn off in order to expel the minority carriers of the Darlington pair at their own charge sweep-out rate. The reverse drive current may be provided by a current transformer, the secondary of which is tapped to the base terminal of the power stage of the Darlington block. In one application, the switching circuit is used in each power switching element in a chopper-inverter drive of an electric vehicle propulsion system.

Common data buffer system. [communication with computational equipment utilized in spacecraft operations

NASA Technical Reports Server (NTRS)

Byrne, F. (Inventor)

1981-01-01

A high speed common data buffer system is described for providing an interface and communications medium between a plurality of computers utilized in a distributed computer complex forming part of a checkout, command and control system for space vehicles and associated ground support equipment. The system includes the capability for temporarily storing data to be transferred between computers, for transferring a plurality of interrupts between computers, for monitoring and recording these transfers, and for correcting errors incurred in these transfers. Validity checks are made on each transfer and appropriate error notification is given to the computer associated with that transfer.

The design of the Comet streamliner: An electric land speed record motorcycle

NASA Astrophysics Data System (ADS)

McMillan, Ethan Alexander

The development of the land speed record electric motorcycle streamliner, the Comet, is discussed herein. Its design process includes a detailed literary review of past and current motorcycle streamliners in an effort to highlight the main components of such a vehicle's design, while providing baseline data for performance comparisons. A new approach to balancing a streamliner at low speeds is also addressed, a system henceforth referred to as landing gear, which has proven an effective means for allowing the driver to control the low speed instabilities of the vehicle with relative ease compared to tradition designs. This is accompanied by a dynamic stability analysis conducted on a test chassis that was developed for the primary purpose of understanding the handling dynamics of streamliners, while also providing a test bed for the implementation of the landing gear system and a means to familiarize the driver to the operation and handling of such a vehicle. Data gathered through the use of GPS based velocity tracking, accelerometers, and a linear potentiometer provided a means to validate a dynamic stability analysis of the weave and wobble modes of the vehicle through linearization of a streamliner model developed in the BikeSIM software suite. Results indicate agreement between the experimental data and the simulation, indicating that the conventional recumbent design of a streamliner chassis is in fact highly stable throughout the performance envelope beyond extremely low speeds. A computational fluid dynamics study was also performed, utilized in the development of the body of the Comet to which a series of tests were conducted in order to develop a shape that was both practical to transport and highly efficient. By creating a hybrid airfoil from a NACA 0018 and NACA 66-018, a drag coefficient of 0.1 and frontal area of 0.44 m2 has been found for the final design. Utilizing a performance model based on the proposed vehicle's motor, its rolling resistance, and the body's aerodynamic drag, the top speed is predicted at 226 mph. Further design considerations are also addressed, including the development of the component level layout of the motorcycle, weighing factors such as safety and ease of fabrication with that of performance and accessibility. At the time of composition, the Comet had started the fabrication process, and it is the intent of the author that the finished product competes in the 2016 Bonneville Motorcycle Speed Trials to set the first world record for a single track electric motorcycle streamliner.

Simultaneous chromatic dispersion monitoring and optical modulation format identification utilizing four wave mixing

NASA Astrophysics Data System (ADS)

Cui, Sheng; Qiu, Chen; Ke, Changjian; He, Sheng; Liu, Deming

2015-11-01

This paper presents a method which is able to monitor the chromatic dispersion (CD) and identify the modulation format (MF) of optical signals simultaneously. This method utilizes the features of the output curve of the highly sensitive all-optical CD monitor based on four wave mixing (FWM). From the symmetric center of the curve CD can be estimated blindly and independently, while from the profile and convergence region of the curve ten commonly used modulation formats can be recognized with simple algorithm based on maximum correlation classifier. This technique does not need any high speed optoelectronics and has no limitation on signal rate. Furthermore it can tolerate large CD distortions and is robust to polarization mode dispersion (PMD) and amplified spontaneous emission (ASE) noise.

Two-dimensional fringe probing of transient liquid temperatures in a mini space.

PubMed

Xue, Zhenlan; Qiu, Huihe

2011-05-01

A 2D fringe probing transient temperature measurement technique based on photothermal deflection theory was developed. It utilizes material's refractive index dependence on temperature gradient to obtain temperature information from laser deflection. Instead of single beam, this method applies multiple laser beams to obtain 2D temperature information. The laser fringe was generated with a Mach-Zehnder interferometer. A transient heating experiment was conducted using an electric wire to demonstrate this technique. Temperature field around a heating wire and variation with time was obtained utilizing the scattering fringe patterns. This technique provides non-invasive 2D temperature measurements with spatial and temporal resolutions of 3.5 μm and 4 ms, respectively. It is possible to achieve temporal resolution to 500 μs utilizing the existing high speed camera.

Structure and Utility of Blind Speed Intervals Associated with Doppler Measurements of Range Rate

DTIC Science & Technology

1993-02-01

computer programming concepts of speed, memory , and data structures that can be exploited to fabricate efficient software realizations of two phase range...to the effect that it is possible to derive a reasonable unambiguous estimate of range rate from the measurement of the pulse-to-pulse phase shift in...the properties of the blind speed intervals generated by the base speeds involved in two measurement equations. Sections 12 through 18 make up the

Attacking 22 entries in rugby union: running demands and differences between successful and unsuccessful entries.

PubMed

Tierney, P; Tobin, D P; Blake, C; Delahunt, E

2017-12-01

Global Positioning System (GPS) technology is commonly utilized in team sports, including rugby union. It has been used to describe the average running demands of rugby union. This has afforded an enhanced understanding of the physical fitness requirements for players. However, research in team sports has suggested that training players relative to average demands may underprepare them for certain scenarios within the game. To date, no research has investigated the running demands of attacking 22 entries in rugby union. Additionally, no research has been undertaken to determine whether differences exist in the running intensity of successful and unsuccessful attacking 22 entries in rugby union. The first aim of this study was to describe the running intensity of attacking 22 entries. The second aim of this study was to investigate whether differences exist in the running intensity of successful and unsuccessful attacking 22 entries. Running intensity was measured using meters per minute (m min -1 ) for (a) total distance, (b) running distance, (c) high-speed running distance, and (d) very high-speed running distance. This study provides normative data for the running intensity of attacking 22 entries in rugby union. Forwards achieved greater high-speed running intensity in successful (3.6 m min -1 ) compared to unsuccessful (1.8 m min -1 ) attacking 22 entries. Forwards should try and achieve greater high-speed running intensity in attacking 22 entries to increase the likelihood of successful outcomes during this period of gameplay. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Study of occupational stress among railway engine pilots

PubMed Central

Kumar, Devesh; Singh, Jai Vir; Kharwar, Poonam S.

2011-01-01

Background: Traffic volume and speed is going to be increased in Indian Railways successively, leading to higher stress in staff connected with train operations. The jobs of railway engine pilots come under the category of high-strain jobs, necessitating a need to conduct multicentric study to unfold the factors associated with occupational stress and organizational strategies. Materials and Methods: Present study covered 185 railway engine pilots and office clerks working in various railway zones by incidental method. Occupational Stress Index (OSI) test developed by Srivastva and Singh, questionnaire of specific stressors constructed by authors and laboratory test battery for psychological screening of high-speed train pilots were used as tools. Results: Means of OSI and all the 12 occupational stressors of railway engine pilots were found significantly higher to that of office clerks. Means of OSI and occupational stressors of goods train pilots were significantly higher in comparison to high-speed train pilots and passenger train pilots. Study revealed positive correlation of speed perception and complex reaction time tests and negative correlation of other constituent tests of laboratory test battery to OSI test. Highest subgroup of stressor observedwas role overload followed by role conflict. Conclusions: These findings provide a prima facie evidence of higher occupational stress among railway engine pilots because of identified specific stressors prevalent in their job and explore the possible intervention strategies for its reduction. Significant correlation is noticed between OSI and laboratory test results, indicating its relevant utility in preliminary psychological screening. PMID:21808497

An integrated analog O/E/O link for multi-channel laser neurons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nahmias, Mitchell A., E-mail: mnahmias@princeton.edu; Tait, Alexander N.; Tolias, Leonidas

2016-04-11

We demonstrate an analog O/E/O electronic link to allow integrated laser neurons to accept many distinguishable, high bandwidth input signals simultaneously. This device utilizes wavelength division multiplexing to achieve multi-channel fan-in, a photodetector to sum signals together, and a laser cavity to perform a nonlinear operation. Its speed outpaces accelerated-time neuromorphic electronics, and it represents a viable direction towards scalable networking approaches.

Dual-Modulation, Dual-Wavelength, Optical Polarimetry System for Glucose Monitoring

DTIC Science & Technology

2016-08-26

dual-wavelength, optical polarimetry system for glucose monitoring 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S) 5d...JBO.21.8.087001] 14. ABSTRACT A dual modulation optical polarimetry system utilizing both laser intensity and polarization modulation was designed...varying birefringence, which is one of the major limitations to the realization of polarimetry for glucose monitoring in the eye. The high-speed less

Numerical Methods for 2-Dimensional Modeling

DTIC Science & Technology

1980-12-01

high-order finite element methods, and a multidimensional version of the method of lines, both utilizing an optimized stiff integrator for the time...integration. The finite element methods have proved disappointing, but the method of lines has provided an unexpectedly large gain in speed. Two...diffusion problems with the same number of unknowns (a 21 x 41 grid), solved by second-order finite element methods, took over seven minutes on the Cray-i

Improving Store Separation Six-Degree-of-Freedom Tools (ISSSDF)

DTIC Science & Technology

2007-01-01

the Australian Air Force. NAVAIR is in the process of preparing a flight clearance for the High Speed Anti- radiation Demonstrator ( HSAD ...program. This clearance will be prepared using the conventional tool NAVSEP. The HSAD missile, however, utilizes an autopilot to move four movable...conventional NAVSEP approach to clear the HSAD missile, it would be desirable to test the TGP and STEME codes for the same case. It would be

Diluted-Magenetic Semiconductor (DMS) Tunneling Devices for the Terahertz Regime

DTIC Science & Technology

2014-12-10

that utilize electron spin properties for achieving higher- level functionality (e.g., transistor action) at very high switching speeds and...influence of the carrier-ion interaction on the properties of a semi-magnetic semi- conductor with a moderate energy gap it is important to keep in mind...the relative numbers: Some of the double barrier experiments, particularly those with II-VI materials are constructed with materials in which the

Hydro pumped storage, international experience: An overview of ASCE task committee report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makarechian, A.H.; Rummel, G.

1995-12-31

This paper presents an overview of a report that is being prepared by ASCE Task Committee on Pumped Storage, International Experience. The reader is referred to the committee report that will be available in 1996. Many pumped storage projects in Europe, but particularly in Japan are becoming an indispensable resource in management of loads and resources on the electrical system. They serve to enhance reliability of the system and to provide for efficient utilization of thermal resources. Pumped storage is increasingly being used as a system management tool. To serve such purposes and to function in this key role, pumpedmore » storage projects are designed for very fast loading and unloading, for very fast mode reversals from pumping to generating and visa versa, for synchronous generation, and more importantly for load ramping during the pumping mode. This is achieved by use of variable-speed pump turbine units. The use of variable-speed units has proven so successful in Japan that many older projects are retrofitted with this new feature. Other interesting equipment applications are discussed including utilization of multi-stage unregulated pump turbines for very high heads (up to 1,250 m), and continued extension of the experience for high head reversible Francis unit, currently in excess of 750 m.« less

Automated sample preparation using membrane microtiter extraction for bioanalytical mass spectrometry.

PubMed

Janiszewski, J; Schneider, P; Hoffmaster, K; Swyden, M; Wells, D; Fouda, H

1997-01-01

The development and application of membrane solid phase extraction (SPE) in 96-well microtiter plate format is described for the automated analysis of drugs in biological fluids. The small bed volume of the membrane allows elution of the analyte in a very small solvent volume, permitting direct HPLC injection and negating the need for the time consuming solvent evaporation step. A programmable liquid handling station (Quadra 96) was modified to automate all SPE steps. To avoid drying of the SPE bed and to enhance the analytical precision a novel protocol for performing the condition, load and wash steps in rapid succession was utilized. A block of 96 samples can now be extracted in 10 min., about 30 times faster than manual solvent extraction or single cartridge SPE methods. This processing speed complements the high-throughput speed of contemporary high performance liquid chromatography mass spectrometry (HPLC/MS) analysis. The quantitative analysis of a test analyte (Ziprasidone) in plasma demonstrates the utility and throughput of membrane SPE in combination with HPLC/MS. The results obtained with the current automated procedure compare favorably with those obtained using solvent and traditional solid phase extraction methods. The method has been used for the analysis of numerous drug prototypes in biological fluids to support drug discovery efforts.

Performance of a distributed superscalar storage server

NASA Technical Reports Server (NTRS)

Finestead, Arlan; Yeager, Nancy

1993-01-01

The RS/6000 performed well in our test environment. The potential exists for the RS/6000 to act as a departmental server for a small number of users, rather than as a high speed archival server. Multiple UniTree Disk Server's utilizing one UniTree Disk Server's utilizing one UniTree Name Server could be developed that would allow for a cost effective archival system. Our performance tests were clearly limited by the network bandwidth. The performance gathered by the LibUnix testing shows that UniTree is capable of exceeding ethernet speeds on an RS/6000 Model 550. The performance of FTP might be significantly faster if asked to perform across a higher bandwidth network. The UniTree Name Server also showed signs of being a potential bottleneck. UniTree sites that would require a high ratio of file creations and deletions to reads and writes would run into this bottleneck. It is possible to improve the UniTree Name Server performance by bypassing the UniTree LibUnix Library altogether and communicating directly with the UniTree Name Server and optimizing creations. Although testing was performed in a less than ideal environment, hopefully the performance statistics stated in this paper will give end-users a realistic idea as to what performance they can expect in this type of setup.

Meissner motor using high-Tc ceramic superconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeoka, A.; Ishikawa, A.; Suzuki, M.

1989-03-01

The authors developed a brand new superconducting motor using high-Tc ceramic superconductors for the first time. This motor utilizes the repulsive force caused by the Meissner effect, which appears below Tc and disappears above that, and is therefore referred to as the Meissner Motor. The motor rotated at a maximum speed of 40 rpm. Though the repulsive force to drive the motor increased with the decrease of temperature or the increase of the gradient magnetic field, it was only about 1.1 gf/g at 77 K in 3500 G/cm. The motor has a maximum torque of 5.0 gf-cm theoretically, but actuallymore » had a torque below 0.66 gf-cm, because it took some time to be cooled below Tc. The rotating speed of the motor was limited by heating ability and its torque was limited by cooling ability.« less

Transition of cavitating flow to supercavitation within Venturi nozzle - hysteresis investigation

NASA Astrophysics Data System (ADS)

Jiří, Kozák; Pavel, Rudolf; Rostislav, Huzlík; Martin, Hudec; Radomír, Chovanec; Ondřej, Urban; Blahoslav, Maršálek; Eliška, Maršálková; František, Pochylý; David, Štefan

Cavitation is usually considered as undesirable phenomena. On the other hand, it can be utilized in many applications. One of the technical applications is using cavitation in water treatment, where hydrodynamic cavitation seems to be effective way how to reduce cyanobacteria within large bulks of water. The main scope of this paper is investigation of the cavitation within Venturi nozzle during the transition from fully developed cavitation to supercavitation regime and vice versa. Dynamics of cavitation was investigated using experimental data of pressure pulsations and analysis of high speed videos, where FFT of the pixel intensity and Proper Orthogonal Decomposition (POD) of the records were done to identify dominant frequencies connected with the presence of cavitation. The methodology of the high speed (HS) records semiautomated analysis using the FFT was described. Obtained results were correlated and above that the possible presence of hysteresis was discussed.

Full range line-field parallel swept source imaging utilizing digital refocusing

NASA Astrophysics Data System (ADS)

Fechtig, Daniel J.; Kumar, Abhishek; Drexler, Wolfgang; Leitgeb, Rainer A.

2015-12-01

We present geometric optics-based refocusing applied to a novel off-axis line-field parallel swept source imaging (LPSI) system. LPSI is an imaging modality based on line-field swept source optical coherence tomography, which permits 3-D imaging at acquisition speeds of up to 1 MHz. The digital refocusing algorithm applies a defocus-correcting phase term to the Fourier representation of complex-valued interferometric image data, which is based on the geometrical optics information of the LPSI system. We introduce the off-axis LPSI system configuration, the digital refocusing algorithm and demonstrate the effectiveness of our method for refocusing volumetric images of technical and biological samples. An increase of effective in-focus depth range from 255 μm to 4.7 mm is achieved. The recovery of the full in-focus depth range might be especially valuable for future high-speed and high-resolution diagnostic applications of LPSI in ophthalmology.

Wave speed propagation measurements on highly attenuative heated materials

DOE PAGES

Moore, David G.; Ober, Curtis C.; Rodacy, Phil J.; ...

2015-09-19

Ultrasonic wave propagation decreases as a material is heated. Two factors that can characterize material properties are changes in wave speed and energy loss from interactions within the media. Relatively small variations in velocity and attenuation can detect significant differences in microstructures. This paper discusses an overview of experimental techniques that document the changes within a highly attenuative material as it is either being heated or cooled from 25°C to 90°C. The experimental set-up utilizes ultrasonic probes in a through-transmission configuration. The waveforms are recorded and analyzed during thermal experiments. To complement the ultrasonic data, a Discontinuous-Galerkin Model (DGM) wasmore » also created which uses unstructured meshes and documents how waves travel in these anisotropic media. This numerical method solves particle motion travel using partial differential equations and outputs a wave trace per unit time. As a result, both experimental and analytical data are compared and presented.« less

Analysis of torque transmitting behavior and wheel slip prevention control during regenerative braking for high speed EMU trains

NASA Astrophysics Data System (ADS)

Xu, Kun; Xu, Guo-Qing; Zheng, Chun-Hua

2016-04-01

The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability, improving the adhesion utilization, and achieving deep energy recovery. There remain technical challenges mainly because of the nonlinear, uncertain, and varying features of wheel-rail contact conditions. This research analyzes the torque transmitting behavior during regenerative braking, and proposes a novel methodology to detect the wheel-rail adhesion stability. Then, applications to the wheel slip prevention during braking are investigated, and the optimal slip ratio control scheme is proposed, which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control. The proposed methodology achieves the optimal braking performance without the wheel-rail contact information. Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.

A flight investigation of oscillating air forces: Equipment and technique

NASA Technical Reports Server (NTRS)

Reed, W. H., III

1975-01-01

The equipment and techniques are described which are to be used in a project aimed at measuring oscillating air forces and dynamic aeroelastic response of a swept wing airplane at high subsonic speeds. Electro-hydraulic inertia type shakers installed in the wing tips will excite various elastic airplane modes while the related oscillating chordwise pressures at two spanwise wing stations and the wing mode shapes are recorded on magnetic tape. The data reduction technique, following the principle of a wattmeter harmonic analyzer employed by Bratt, Wight, and Tilly, utilizes magnetic tape and high speed electronic multipliers to record directly the real and imaginary components of oscillatory data signals relative to a simple harmonic reference signal. Through an extension of this technique an automatic flight-flutter-test data analyzer is suggested in which vector plots of mechanical admittance or impedance would be plotted during the flight test.

Comparing cutting efficiencies of diamond burs using a high-speed electric handpiece.

PubMed

Chung, Evelyn M; Sung, Eric C; Wu, Ben; Caputo, Angelo A

2006-01-01

This study sought to compare the cutting efficiency of different diamond burs on initial use as well as during repeated use, alternating with sterilization. Long, round-end, tapered diamond burs with similar diameter, profile, and diamond coarseness (125-150 microm grit) were used. A high-torque, high-speed electric handpiece (set at 200,000 rpm) was utilized with a coolant flow rate of 25 mL/min. Burs were tested under a constant load of 170 g while cuts were made on a machinable ceramic substrate block. Each bur was subjected to five consecutive cuts for 30 seconds of continuous operation and the cutting depths were measured. All burs performed similarly on the first cut. Cutting efficiencies for three of the bur groups decreased significantly after the first cycle; however, by the fifth cycle, all bur groups performed similarly without any significant differences (p > 0.05). A scanning electron microscope revealed significant crystal loss after each use.

Design consideration in constructing high performance embedded Knowledge-Based Systems (KBS)

NASA Technical Reports Server (NTRS)

Dalton, Shelly D.; Daley, Philip C.

1988-01-01

As the hardware trends for artificial intelligence (AI) involve more and more complexity, the process of optimizing the computer system design for a particular problem will also increase in complexity. Space applications of knowledge based systems (KBS) will often require an ability to perform both numerically intensive vector computations and real time symbolic computations. Although parallel machines can theoretically achieve the speeds necessary for most of these problems, if the application itself is not highly parallel, the machine's power cannot be utilized. A scheme is presented which will provide the computer systems engineer with a tool for analyzing machines with various configurations of array, symbolic, scaler, and multiprocessors. High speed networks and interconnections make customized, distributed, intelligent systems feasible for the application of AI in space. The method presented can be used to optimize such AI system configurations and to make comparisons between existing computer systems. It is an open question whether or not, for a given mission requirement, a suitable computer system design can be constructed for any amount of money.

NASA and Industry Benefits of ACTS High Speed Network Interoperability Experiments

NASA Technical Reports Server (NTRS)

Zernic, M. J.; Beering, D. R.; Brooks, D. E.

2000-01-01

This paper provides synopses of the design. implementation, and results of key high data rate communications experiments utilizing the technologies of NASA's Advanced Communications Technology Satellite (ACTS). Specifically, the network protocol and interoperability performance aspects will be highlighted. The objectives of these key experiments will be discussed in their relevant context to NASA missions, as well as, to the comprehensive communications industry. Discussion of the experiment implementation will highlight the technical aspects of hybrid network connectivity, a variety of high-speed interoperability architectures, a variety of network node platforms, protocol layers, internet-based applications, and new work focused on distinguishing between link errors and congestion. In addition, this paper describes the impact of leveraging government-industry partnerships to achieve technical progress and forge synergistic relationships. These relationships will be the key to success as NASA seeks to combine commercially available technology with its own internal technology developments to realize more robust and cost effective communications for space operations.

The Utility of the Supine-to-Stand Test as a Measure of Functional Motor Competence in Children Aged 5–9 Years

PubMed Central

Duncan, Michael J.; Lawson, Chelsey; Walker, Leanne Jaye; Stodden, David; Eyre, Emma L. J.

2017-01-01

This study examined how supine-to-stand (STS) performance is related to process and product assessment of motor competence (MC) in children. Ninety-one children aged 5–9 years were assessed for process and product MC (10 m running speed and standing long jump) as well as process and product measures of STS. Tertiles were created for STS process and STS product scores to create 3 groups reflecting low, medium, and high STS competency. ANCOVA analysis, controlling for age, for process STS, indicated that process MC was significantly higher in children, classified as medium STS (p = 0.048) and high STS (p = 0.011) competence, and that 10 m run speed was slower for low STS compared to medium (p = 0.019) and high STS (p = 0.004). For product STS tertiles, process MC was significantly higher for children in the lowest (fastest) STS tertile compared to those in the medium highest (slowest) tertile (p = 0.01). PMID:29910427

Design study of wind turbines 50 kW to 3000 kW for electric utility applications: Analysis and design

NASA Technical Reports Server (NTRS)

1976-01-01

In the conceptual design task, several feasible wind generator systems (WGS) configurations were evaluated, and the concept offering the lowest energy cost potential and minimum technical risk for utility applications was selected. In the optimization task, the selected concept was optimized utilizing a parametric computer program prepared for this purpose. In the preliminary design task, the optimized selected concept was designed and analyzed in detail. The utility requirements evaluation task examined the economic, operational, and institutional factors affecting the WGS in a utility environment, and provided additional guidance for the preliminary design effort. Results of the conceptual design task indicated that a rotor operating at constant speed, driving an AC generator through a gear transmission is the most cost effective WGS configuration. The optimization task results led to the selection of a 500 kW rating for the low power WGS and a 1500 kW rating for the high power WGS.

Optimized Finite-Difference Coefficients for Hydroacoustic Modeling

NASA Astrophysics Data System (ADS)

Preston, L. A.

2014-12-01

Responsible utilization of marine renewable energy sources through the use of current energy converter (CEC) and wave energy converter (WEC) devices requires an understanding of the noise generation and propagation from these systems in the marine environment. Acoustic noise produced by rotating turbines, for example, could adversely affect marine animals and human-related marine activities if not properly understood and mitigated. We are utilizing a 3-D finite-difference acoustic simulation code developed at Sandia that can accurately propagate noise in the complex bathymetry in the near-shore to open ocean environment. As part of our efforts to improve computation efficiency in the large, high-resolution domains required in this project, we investigate the effects of using optimized finite-difference coefficients on the accuracy of the simulations. We compare accuracy and runtime of various finite-difference coefficients optimized via criteria such as maximum numerical phase speed error, maximum numerical group speed error, and L-1 and L-2 norms of weighted numerical group and phase speed errors over a given spectral bandwidth. We find that those coefficients optimized for L-1 and L-2 norms are superior in accuracy to those based on maximal error and can produce runtimes of 10% of the baseline case, which uses Taylor Series finite-difference coefficients at the Courant time step limit. We will present comparisons of the results for the various cases evaluated as well as recommendations for utilization of the cases studied. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Grumman WS33 wind system: prototype construction and testing, Phase II technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adler, F.M.; Henton, P.; King, P.W.

1980-11-01

The prototype fabrication and testing of the 8 kW small wind energy conversion system are reported. The turbine is a three-bladed, down-wind machine designed to interface directly with an electrical utility network. The machine as finally fabricated is rated at 15 kW at 24 mpH and peak power of 18 kW at 35 mph. Utility compatible electrical power is generated in winds between a cut-in speed of 9 mph and a cut-out speed of 35 mph by using the torque characteristics of the unit's induction generator combined with the rotor aerodynamics to maintain essentially constant speed. Inspection procedures, pre-delivery testing,more » and a cost analysis are included.« less

Breakdown parameter for kinetic modeling of multiscale gas flows.

PubMed

Meng, Jianping; Dongari, Nishanth; Reese, Jason M; Zhang, Yonghao

2014-06-01

Multiscale methods built purely on the kinetic theory of gases provide information about the molecular velocity distribution function. It is therefore both important and feasible to establish new breakdown parameters for assessing the appropriateness of a fluid description at the continuum level by utilizing kinetic information rather than macroscopic flow quantities alone. We propose a new kinetic criterion to indirectly assess the errors introduced by a continuum-level description of the gas flow. The analysis, which includes numerical demonstrations, focuses on the validity of the Navier-Stokes-Fourier equations and corresponding kinetic models and reveals that the new criterion can consistently indicate the validity of continuum-level modeling in both low-speed and high-speed flows at different Knudsen numbers.

Passive magnetic bearing systems stabilizer/bearing utilizing time-averaging of a periodic magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Post, Richard F.

A high-stiffness stabilizer/bearings for passive magnetic bearing systems is provide where the key to its operation resides in the fact that when the frequency of variation of the repelling forces of the periodic magnet array is large compared to the reciprocal of the growth time of the unstable motion, the rotating system will feel only the time-averaged value of the force. When the time-averaged value of the force is radially repelling by the choice of the geometry of the periodic magnet array, the Earnshaw-related unstable hit motion that would occur at zero rotational speed is suppressed when the system ismore » rotating at operating speeds.« less

Fast Fourier transform-based Retinex and alpha-rooting color image enhancement

NASA Astrophysics Data System (ADS)

Grigoryan, Artyom M.; Agaian, Sos S.; Gonzales, Analysa M.

2015-05-01

Efficiency in terms of both accuracy and speed is highly important in any system, especially when it comes to image processing. The purpose of this paper is to improve an existing implementation of multi-scale retinex (MSR) by utilizing the fast Fourier transforms (FFT) within the illumination estimation step of the algorithm to improve the speed at which Gaussian blurring filters were applied to the original input image. In addition, alpha-rooting can be used as a separate technique to achieve a sharper image in order to fuse its results with those of the retinex algorithm for the sake of achieving the best image possible as shown by the values of the considered color image enhancement measure (EMEC).

The seasonal-cycle climate model

NASA Technical Reports Server (NTRS)

Marx, L.; Randall, D. A.

1981-01-01

The seasonal cycle run which will become the control run for the comparison with runs utilizing codes and parameterizations developed by outside investigators is discussed. The climate model currently exists in two parallel versions: one running on the Amdahl and the other running on the CYBER 203. These two versions are as nearly identical as machine capability and the requirement for high speed performance will allow. Developmental changes are made on the Amdahl/CMS version for ease of testing and rapidity of turnaround. The changes are subsequently incorporated into the CYBER 203 version using vectorization techniques where speed improvement can be realized. The 400 day seasonal cycle run serves as a control run for both medium and long range climate forecasts alsensitivity studies.

Coaxial Compound Helicopter for Confined Urban Operations

NASA Technical Reports Server (NTRS)

Johnson, Wayne; Elmore, Joshua F.; Keen, Ernest B.; Gallaher, Andrew T.; Nunez, Gerardo F.

2016-01-01

A rotorcraft was designed for military operations in a confined urban environment. The specifications included major increases in useful load, range, and speed relative current aircraft capabilities, with a size constraint based on the dimensions of urban streets and intersections. Analysis showed that this combination of requirements is best satisfied by a coaxial main-rotor configuration, with lift compounding to off-load the rotors at high speed, and ducted fans under the rotor disk for propulsion. The baseline design is described, and the aircraft performance is summarized for utility, attack, MEDEVAC, and cargo delivery missions. The impact on size and performance is examined for a number of excursions, including lift-offset main rotors. Technology development required to achieve this advance in capability is recommended.

GaAs/Ge Solar Powered Aircraft

NASA Technical Reports Server (NTRS)

Colozza, Anthony J.; Scheiman, David A.; Brinker, David J.

1998-01-01

Unmanned Aerial Vehicles (UAV) are being proposed for many applications for many applications including surveillance, mapping and atmospheric studies. These applications require a lightweight, low speed, medium to long duration aircraft. Due to the weight, speed, and altitude constraints imposed on such an aircraft, solar array generated electric power can be a viable alternative to air-breathing engines for certain missions. Development of such an aircraft is currently being funded under the Environmental Research Aircraft and Sensor Technology (ERAST) program. NASA Lewis Research Center (LeRC) has built a Solar Electric Airplane to demonstrate UAV technology. This aircraft utilizes high efficiency Applied Solar Energy Corporation (ASEC) GaAs/Ge space solar cells. The cells have been provided by the Air Force through the ManTech Office.

Application of Rapid Prototyping Methods to High-Speed Wind Tunnel Testing

NASA Technical Reports Server (NTRS)

Springer, A. M.

1998-01-01

This study was undertaken in MSFC's 14-Inch Trisonic Wind Tunnel to determine if rapid prototyping methods could be used in the design and manufacturing of high speed wind tunnel models in direct testing applications, and if these methods would reduce model design/fabrication time and cost while providing models of high enough fidelity to provide adequate aerodynamic data, and of sufficient strength to survive the test environment. Rapid prototyping methods utilized to construct wind tunnel models in a wing-body-tail configuration were: fused deposition method using both ABS plastic and PEEK as building materials, stereolithography using the photopolymer SL-5170, selective laser sintering using glass reinforced nylon, and laminated object manufacturing using plastic reinforced with glass and 'paper'. This study revealed good agreement between the SLA model, the metal model with an FDM-ABS nose, an SLA nose, and the metal model for most operating conditions, while the FDM-ABS data diverged at higher loading conditions. Data from the initial SLS model showed poor agreement due to problems in post-processing, resulting in a different configuration. A second SLS model was tested and showed relatively good agreement. It can be concluded that rapid prototyping models show promise in preliminary aerodynamic development studies at subsonic, transonic, and supersonic speeds.

A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors.

PubMed

Gao, Zhiyuan; Yang, Congjie; Xu, Jiangtao; Nie, Kaiming

2015-11-06

This paper presents a dynamic range (DR) enhanced readout technique with a two-step time-to-digital converter (TDC) for high speed linear CMOS image sensors. A multi-capacitor and self-regulated capacitive trans-impedance amplifier (CTIA) structure is employed to extend the dynamic range. The gain of the CTIA is auto adjusted by switching different capacitors to the integration node asynchronously according to the output voltage. A column-parallel ADC based on a two-step TDC is utilized to improve the conversion rate. The conversion is divided into coarse phase and fine phase. An error calibration scheme is also proposed to correct quantization errors caused by propagation delay skew within -T(clk)~+T(clk). A linear CMOS image sensor pixel array is designed in the 0.13 μm CMOS process to verify this DR-enhanced high speed readout technique. The post simulation results indicate that the dynamic range of readout circuit is 99.02 dB and the ADC achieves 60.22 dB SNDR and 9.71 bit ENOB at a conversion rate of 2 MS/s after calibration, with 14.04 dB and 2.4 bit improvement, compared with SNDR and ENOB of that without calibration.

Time-stretch microscopy based on time-wavelength sequence reconstruction from wideband incoherent source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Chi, E-mail: chizheung@gmail.com; Xu, Yiqing; Wei, Xiaoming

2014-07-28

Time-stretch microscopy has emerged as an ultrafast optical imaging concept offering the unprecedented combination of the imaging speed and sensitivity. However, dedicated wideband and coherence optical pulse source with high shot-to-shot stability has been mandated for time-wavelength mapping—the enabling process for ultrahigh speed wavelength-encoded image retrieval. From the practical point of view, exploiting methods to relax the stringent requirements (e.g., temporal stability and coherence) for the source of time-stretch microscopy is thus of great value. In this paper, we demonstrated time-stretch microscopy by reconstructing the time-wavelength mapping sequence from a wideband incoherent source. Utilizing the time-lens focusing mechanism mediated bymore » a narrow-band pulse source, this approach allows generation of a wideband incoherent source, with the spectral efficiency enhanced by a factor of 18. As a proof-of-principle demonstration, time-stretch imaging with the scan rate as high as MHz and diffraction-limited resolution is achieved based on the wideband incoherent source. We note that the concept of time-wavelength sequence reconstruction from wideband incoherent source can also be generalized to any high-speed optical real-time measurements, where wavelength is acted as the information carrier.« less

Evaluation of radar activated changeable message sign for work zone speed control.

DOT National Transportation Integrated Search

2002-01-01

The Maine Department of Transportation recently tested new equipment designed to help reduce the : incidence of speeding in construction work zones. The project utilized a radar-activated, trailer mounted, : changeable message sign (CMS). The CMS spe...

High friction interactive aircraft tire-runway systems

NASA Technical Reports Server (NTRS)

Clark, S. K.

1974-01-01

The principle of utilizing geometric interaction between runway asperities and tire pattern design is discussed, and a theoretical basis is presented for substantial enhancement of frictional effects by this process. Test data confirming this is given. First order analytical expressions are given for the increased friction coefficients and for the engagement distances required. High speed friction data on a 7.00 x 8 aircraft tire is presented confirming this. Example design geometries are shown for the tire tread groove pattern, and designs and materials are discussed for the asperity grid and its attachment system.

Cerium-doped scintillating fused-silica fibers

NASA Astrophysics Data System (ADS)

Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P.; Faulkner, J.; Kunori, S.

2018-04-01

We report on a set of measurements made on (scintillating) cerium-doped fused-silica fibers using high-energy particle beams. These fibers were uniformly embedded in a copper absorber in order to utilize electromagnetic showers as a source of charged particles for generating signals. This new type of cerium-doped fiber potentially offers myriad new applications in calorimeters in high-energy physics, tracking systems, and beam monitoring detectors for future applications. The light yield, pulse shape, attenuation length, and light propagation speeds are given and discussed. Possible future applications are also explored.

MetaUniDec: High-Throughput Deconvolution of Native Mass Spectra

NASA Astrophysics Data System (ADS)

Reid, Deseree J.; Diesing, Jessica M.; Miller, Matthew A.; Perry, Scott M.; Wales, Jessica A.; Montfort, William R.; Marty, Michael T.

2018-04-01

The expansion of native mass spectrometry (MS) methods for both academic and industrial applications has created a substantial need for analysis of large native MS datasets. Existing software tools are poorly suited for high-throughput deconvolution of native electrospray mass spectra from intact proteins and protein complexes. The UniDec Bayesian deconvolution algorithm is uniquely well suited for high-throughput analysis due to its speed and robustness but was previously tailored towards individual spectra. Here, we optimized UniDec for deconvolution, analysis, and visualization of large data sets. This new module, MetaUniDec, centers around a hierarchical data format 5 (HDF5) format for storing datasets that significantly improves speed, portability, and file size. It also includes code optimizations to improve speed and a new graphical user interface for visualization, interaction, and analysis of data. To demonstrate the utility of MetaUniDec, we applied the software to analyze automated collision voltage ramps with a small bacterial heme protein and large lipoprotein nanodiscs. Upon increasing collisional activation, bacterial heme-nitric oxide/oxygen binding (H-NOX) protein shows a discrete loss of bound heme, and nanodiscs show a continuous loss of lipids and charge. By using MetaUniDec to track changes in peak area or mass as a function of collision voltage, we explore the energetic profile of collisional activation in an ultra-high mass range Orbitrap mass spectrometer. [Figure not available: see fulltext.

Preparative separation of bioactive compounds from essential oil of Flaveria bidentis (L.) Kuntze using steam distillation extraction and one step high-speed counter-current chromatography.

PubMed

Wei, Yun; Du, Jilin; Lu, Yuanyuan

2012-10-01

In order to utilize and control the invasive weed, bioactive compounds from essential oil of Flaveria bidentis (L.) Kuntze were studied. Steam distillation extraction and one step high-speed counter-current chromatography were applied to separate and purify the caryophyllene oxide, 7,11-dimethyl-3-methylene-1,6,10-dodecatriene, and caryophyllene from essential oil of Flaveria bidentis (L.) Kuntze. The two-phase solvent system containing n-hexane/acetonitrile/ethanol (5:4:3, v/v/v) was selected for the one step separation mode according to the partition coefficient values (K) of the target compounds and the separation factor (α). The purity of each isolated fraction after a single high-speed counter-current chromatography run was determined by high performance liquid chromatography. A 3.2 mg of caryophyllene oxide at a purity of 92.6%, 10.4 mg of 7,11-dimethyl-3-methylene-1,6,10-dodecatriene at a purity of 99.1% and 5.7 mg of caryophyllene at a purity of 98.8% were obtained from 200 mg essential oil of Flaveria bidentis (L.) Kuntze. The chemical structures of these components were identified by GC-MS, (1) H-NMR, and (13) C-NMR. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of the impact of cruise speed on scheduling and productivity of commercial transport aircraft

NASA Technical Reports Server (NTRS)

Bond, E. Q.; Carroll, E. A.; Flume, R. A.

1977-01-01

A comparison is made between airplane productivity and utilization levels derived from commercial airline type schedules which were developed for two subsonic and four supersonic cruise speed aircraft. The cruise speed component is the only difference between the schedules which are based on 1995 passenger demand forecasts. Productivity-to-speed relationships were determined for the three discrete route systems: North Atlantic, Trans-Pacific, and North-South America. Selected combinations of these route systems were also studied. Other areas affecting the productivity-to-speed relationship such as aircraft design range and scheduled turn time were examined.

A novel ultrasonic method for measuring breast density and breast cancer risk

NASA Astrophysics Data System (ADS)

Glide-Hurst, Carri K.; Duric, Neb; Littrup, Peter J.

2008-03-01

Women with high mammographic breast density are at 4- to 6-fold increased risk of developing breast cancer compared to women with fatty breasts. However, current breast density estimations rely on mammography, which cannot provide accurate volumetric breast representation. Therefore, we explored two techniques of breast density evaluation via ultrasound tomography. A sample of 93 patients was imaged with our clinical prototype; each dataset contained 45-75 tomograms ranging from near the chest wall through the nipple. Whole breast acoustic velocity was determined by creating image stacks and evaluating the sound speed frequency distribution. Ultrasound percent density (USPD) was determined by segmenting high sound speed areas from each tomogram using k-means clustering, integrating over the entire breast, and dividing by total breast area. Both techniques were independently evaluated using two mammographic density measures: (1) qualitative, determined by a radiologist's visual assessment using BI-RADS Categories, and (2) quantitative, via semi-automatic segmentation to calculate mammographic percent density (MPD) for craniocaudal and medio-lateral oblique mammograms. ~140 m/s difference in acoustic velocity was observed between fatty and dense BI-RADS Categories. Increased sound speed was found with increased BI-RADS Category and quantitative MPD. Furthermore, strong positive associations between USPD, BI-RADS Category, and calculated MPD were observed. These results confirm that utilizing sound speed, both for whole-breast evaluation and segmenting locally, can be implemented to evaluate breast density.

The high speed buffer board: A SAIL EIA-485 communications accelerator card for the vector measuring current meter

NASA Astrophysics Data System (ADS)

Singer, Robin; Butler, Douglas M.

1990-07-01

A High Speed Buffer Board (HSBB) was developed for the Vector Measuring Current Meter (VMCM) to implement the transmission of data at 9600 baud over an EIA-485 link. The HSBB significantly extends the VMCM communication functionality, which was previously limited to 300 baud transmission via 20mA current loop or FSK telemetry. The increased speed allows rapid sampling of a large number of current meters on a common cable and the EIA-485 circuitry, which was designed for low power operation, provides a useful multipoint communication method for data transmission over long cable lengths. SAIL protocol (IEEE 997) was utilized to coordinate data transfer by the instruments on a common link. An MC68HC11 microcontroller resides in the VMCM, buffering data it receives at 300 baud from the VMCM UART. In response to a jumper selectable SAIL address, the MC68HC11 offloads the data 9600 baud via EIA-485 to the SAIL controller. Synchronous data collection from many instruments is ensured by the SAIL synoptic set command and an embedded resynchronization/reset command. The low power consumption allows deployments of six months or more with a standard VMCM battery stack.

Optimization of Angular-Momentum Biases of Reaction Wheels

NASA Technical Reports Server (NTRS)

Lee, Clifford; Lee, Allan

2008-01-01

RBOT [RWA Bias Optimization Tool (wherein RWA signifies Reaction Wheel Assembly )] is a computer program designed for computing angular momentum biases for reaction wheels used for providing spacecraft pointing in various directions as required for scientific observations. RBOT is currently deployed to support the Cassini mission to prevent operation of reaction wheels at unsafely high speeds while minimizing time in undesirable low-speed range, where elasto-hydrodynamic lubrication films in bearings become ineffective, leading to premature bearing failure. The problem is formulated as a constrained optimization problem in which maximum wheel speed limit is a hard constraint and a cost functional that increases as speed decreases below a low-speed threshold. The optimization problem is solved using a parametric search routine known as the Nelder-Mead simplex algorithm. To increase computational efficiency for extended operation involving large quantity of data, the algorithm is designed to (1) use large time increments during intervals when spacecraft attitudes or rates of rotation are nearly stationary, (2) use sinusoidal-approximation sampling to model repeated long periods of Earth-point rolling maneuvers to reduce computational loads, and (3) utilize an efficient equation to obtain wheel-rate profiles as functions of initial wheel biases based on conservation of angular momentum (in an inertial frame) using pre-computed terms.

Environmental Assessment for Establishment of an Off-Highway Vehicle (OHV) Program at Arnold Air Force Base, Tennessee

DTIC Science & Technology

2010-05-01

OHV area for the following resource areas: geomorphology and soils , water quality and hydrology, biological resources, cultural resources, and...established in such a mmmer to avoid wetlands and minimize stream crossings and interaction with highly erodible soils . If such areas are utilized...operational constraints would be implemented that would minimize impacts in these areas, such as restricted use in wet soils and speed limits. At

Fundamental Physics and Practical Applications of Electromagnetic Local Flow Control in High Speed Flows (Rutgers)

DTIC Science & Technology

2010-02-16

field. Techniques utilizing this design use an open- loop control and no flow monitoring sensors are required. Conversely, reactive (or closed - loop ...and closed (dashed line) configuration. 38 closed configuration described above, the ambiguity in the critical limits of the transition...flow; a new vortex is then shed from the cavity leading edge, closing the feedback loop .[31] Open cavities with an L/D approximately greater than

Combined application of FBG and PZT sensors for plantar pressure monitoring at low and high speed walking.

PubMed

Suresh, R; Bhalla, S; Singh, C; Kaur, N; Hao, J; Anand, S

2015-01-01

Clinical monitoring of planar pressure is vital in several pathological conditions, such as diabetes, where excess pressure might have serious repercussions on health of the patient, even to the extent of amputation. The main objective of this paper is to experimentally evaluate the combined application of the Fibre Bragg Grating (FBG) and the lead zirconate titanate (PZT) piezoceramic sensors for plantar pressure monitoring during walk at low and high speeds. For fabrication of the pressure sensors, the FBGs are embedded within layers of carbon composite material and stacked in an arc shape. From this embedding technique, average pressure sensitivity of 1.3 pm/kPa and resolution of nearly 0.8 kPa is obtained. These sensors are found to be suitable for measuring the static and the low-speed walk generated foot pressure. Simultaneously, PZT patches of size 10 × 10 × 0.3 mm were used as sensors, utilizing the d_{33} (thickness) coupling mode. A sensitivity of 7.06 mV/kPa and a pressure resolution of 0.14 kPa is obtained from these sensors, which are found to be suitable for foot pressure measurement during high speed walking and running. Both types of sensors are attached to the underside of the sole of commercially available shoes. In the experiments, a healthy male subject walks/runs over the treadmill wearing the fabricated shoes at various speeds and the peak pressure is measured using both the sensors. Commercially available low-cost hardware is used for interrogation of the two sensor types. The test results clearly show the feasibility of the FBG and the PZT sensors for measurement of plantar pressure. The PZT sensors are more accurate for measurement of pressure during walking at high speeds. The FBG sensors, on the other hand, are found to be suitable for static and quasi-dynamic (slow walking) conditions. Typically, the measured pressure varied from 400 to 600 kPa below the forefoot and 100 to 1000 kPa below the heel as the walking speed varied from 1 kilometer per hour (kmph) to 7 kmph. When instrumented in combination, the two sensors can enable measurements ranging from static to high speed conditions Both the sensor types are rugged, small sized and can be easily embedded in commercial shoes and enable plantar pressure measurement in a cost-effective manner. This research is expected to have application in the treatment of patients suffering from diabetes and gonarthrosis.

Wind tunnel test of Teledyne Geotech model 1564B cup anemometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, M.J.; Addis, R.P.

1991-04-04

The Department of Energy (DOE) Environment, Safety and Health Compliance Assessment (Tiger Team) of the Savannah River Site (SRS) questioned the method by which wind speed sensors (cup anemometers) are calibrated by the Environmental Technology Section (ETS). The Tiger Team member was concerned that calibration data was generated by running the wind tunnel to only 26 miles per hour (mph) when speeds exceeding 50 mph are readily obtainable. A wind tunnel experiment was conducted and confirmed the validity of the practice. Wind speeds common to SRS (6 mph) were predicted more accurately by 0--25 mph regression equations than 0--50 mphmore » regression equations. Higher wind speeds were slightly overpredicted by the 0--25 mph regression equations when compared to 0--50 mph regression equations. However, the greater benefit of more accurate lower wind speed predictions accuracy outweight the benefit of slightly better high (extreme) wind speed predictions. Therefore, it is concluded that 0--25 mph regression equations should continue to be utilized by ETS at SRS. During the Department of Energy Tiger Team audit, concerns were raised about the calibration of SRS cup anemometers. Wind speed is measured by ETS with Teledyne Geotech model 1564B cup anemometers, which are calibrated in the ETS wind tunnel. Linear regression lines are fitted to data points of tunnel speed versus anemometer output voltages up to 25 mph. The regression coefficients are then implemented into the data acquisition computer software when an instrument is installed in the field. The concern raised was that since the wind tunnel at SRS is able to generate a maximum wind speed higher than 25 mph, errors may be introduced in not using the full range of the wind tunnel.« less

Wind tunnel test of Teledyne Geotech model 1564B cup anemometer

NASA Astrophysics Data System (ADS)

Parker, M. J.; Addis, R. P.

1991-04-01

The Department of Energy (DOE) Environment, Safety, and Health Compliance Assessment (Tiger Team) of the Savannah River Site (SRS) questioned the method by which wind speed sensors (cup anemometers) are calibrated by the Environmental Technology Section (ETS). The Tiger Team member was concerned that calibration data was generated by running the wind tunnel to only 26 miles per hour (mph) when speeds exceeding 50 mph are readily obtainable. A wind tunnel experiment was conducted and confirmed the validity of the practice. Wind speeds common to SRS (6 mph) were predicted more accurately by 0-25 mph regression equations than 0-50 mph regression equations. Higher wind speeds were slightly overpredicted by the 0-25 mph regression equations when compared to 0-50 mph regression equations. However, the greater benefit of more accurate lower wind speed predictions accuracy outweigh the benefit of slightly better high (extreme) wind speed predictions. Therefore, it is concluded that 0-25 mph regression equations should continue to be utilized by ETS at SRS. During the Department of Energy Tiger Team audit, concerns were raised about the calibration of SRS cup anemometers. Wind speed is measured by ETS with Teledyne Geotech model 1564B cup anemometers, which are calibrated in the ETS wind tunnel. Linear regression lines are fitted to data points of tunnel speed versus anemometer output voltages up to 25 mph. The regression coefficients are then implemented into the data acquisition computer software when an instrument is installed in the field. The concern raised was that since the wind tunnel at SRS is able to generate a maximum wind speed higher than 25 mph, errors may be introduced in not using the full range of the wind tunnel.

Design study of steel V-Belt CVT for electric vehicles

NASA Technical Reports Server (NTRS)

Swain, J. C.; Klausing, T. A.; Wilcox, J. P.

1980-01-01

A continuously variable transmission (CVT) design layout was completed. The intended application was for coupling the flywheel to the driveline of a flywheel battery hybrid electric vehicle. The requirements were that the CVT accommodate flywheel speeds from 14,000 to 28,000 rpm and driveline speeds of 850 to 5000 rpm without slipping. Below 850 rpm a slipping clutch was used between the CVT and the driveline. The CVT was required to accommodate 330 ft-lb maximum torque and 100 hp maximum transient. The weighted average power was 22 hp, the maximum allowable full range shift time was 2 seconds and the required lift was 2600 hours. The resulting design utilized two steel V-belts in series to accommodate the required wide speed ratio. The size of the CVT, including the slipping clutch, was 20.6 inches long, 9.8 inches high and 13.8 inches wide. The estimated weight was 155 lb. An overall potential efficiency of 95 percent was projected for the average power condition.

Seeing the forest for the trees: Networked workstations as a parallel processing computer

NASA Technical Reports Server (NTRS)

Breen, J. O.; Meleedy, D. M.

1992-01-01

Unlike traditional 'serial' processing computers in which one central processing unit performs one instruction at a time, parallel processing computers contain several processing units, thereby, performing several instructions at once. Many of today's fastest supercomputers achieve their speed by employing thousands of processing elements working in parallel. Few institutions can afford these state-of-the-art parallel processors, but many already have the makings of a modest parallel processing system. Workstations on existing high-speed networks can be harnessed as nodes in a parallel processing environment, bringing the benefits of parallel processing to many. While such a system can not rival the industry's latest machines, many common tasks can be accelerated greatly by spreading the processing burden and exploiting idle network resources. We study several aspects of this approach, from algorithms to select nodes to speed gains in specific tasks. With ever-increasing volumes of astronomical data, it becomes all the more necessary to utilize our computing resources fully.

Wind Power Potential at Abandoned Mines in Korea

NASA Astrophysics Data System (ADS)

jang, M.; Choi, Y.; Park, H.; Go, W.

2013-12-01

This study performed an assessment of wind power potential at abandoned mines in the Kangwon province by analyzing gross energy production, greenhouse gas emission reduction and economic effects estimated from a 600 kW wind turbine. Wind resources maps collected from the renewable energy data center in Korea Institute of Energy Research(KIER) were used to determine the average wind speed, temperature and atmospheric pressure at hub height(50 m) for each abandoned mine. RETScreen software developed by Natural Resources Canada(NRC) was utilized for the energy, emission and financial analyses of wind power systems. Based on the results from 5 representative mining sites, we could know that the average wind speed at hub height is the most critical factor for assessing the wind power potential. Finally, 47 abandoned mines that have the average wind speed faster than 6.5 m/s were analyzed, and top 10 mines were suggested as relatively favorable sites with high wind power potential in the Kangwon province.

Solar Pond Potential as A New Renewable Energy in South Sulawesi

NASA Astrophysics Data System (ADS)

Fadliah Baso, Nur; Chaerah Gunadin, Indar; Yusran

2018-03-01

Renewable energy sources need to be developed to maintain the electric energy availability by utilizing oceanic energy, namely solar pond energy. This energy is highly influenced by several factors including salinity, air temperature and solar radiation. This study was focused on finding the potential of solar pond in South Sulawesi, a region with fairly high solar radiation and abundant salt water raw materials availability. The method used in this study was analyzing the values from the mathematic models of daily horizontal solar radiation, air temperature, wind speed, relative humidity and atmospheric pressure for the last 22 years which were finalized using MATLAB. The findings of this study will show the areas with good potentials to apply solar pond in South Sulawesi that can be utilized in various fields including power generator, industrial heating process, desalination and heating for biomass conversion.

Performance improvement of PEFC modules with cell containing low amount of platinum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyake, Y.; Kadowaki, M.; Hamada, A.

1996-12-31

Cell components of the PEFC module were studied to improve the module performance. The cell performance in a high air utilization region was improved by selecting an air channel design of the separator in which high air flow speed was obtained. Optimization of Teflon{reg_sign} amount on the cathode backing carbon paper also contributed the cell performance. Modifications of the gas channel design and the backing carbon paper were carried out in a 200 cm{sup 2} x 20-cell module and 36-cell module. Dependence of air utilization on module performance was remarkably improved and power density of more than 0.3 W/cm{sup 2}more » was achieved in spite of the platinum amount in the cells was decreased to 1.1 Mg/cm{sup 2}.« less

Development of ATC for High Speed and High Density Commuter Line

NASA Astrophysics Data System (ADS)

Okutani, Tamio; Nakamura, Nobuyuki; Araki, Hisato; Irie, Shouji; Osa, Hiroki; Sano, Minoru; Ikeda, Keigo; Ozawa, Hiroyuki

A new ATC (Automatic Train Control) system has been developed with solutions to realize short train headway by assured braking utilizing digital data transmission via rails; the digital data for the ATP (Automatic Train Protection) function; and to achieve EMC features for both AC and DC sections. The DC section is of the unprecedented DC traction power supply system utilizing IGBT PWM converter at all DC substations. Within the AC section, train traction force is controlled by PWM converter/inverters. The carrier frequencies of the digital data signals and chopping frequency of PWM traction power converters on-board are decided via spectral analysis of noise up to degraded mode cases of equipment. Developed system was equipped to the Tukuba Express Line, new commuter line of Tokyo metropolitan area, and opened since Aug. 2005.

Background and system description of the Mod 1 wind turbine generator

NASA Technical Reports Server (NTRS)

Ernst, E. H.

1978-01-01

The Mod-1 wind turbine considered is a large utility-class machine, operating in the high wind regime, which has the potential for generation of utility grade power at costs competitive with other alternative energy sources. A Mod-1 wind turbine generator (WTG) description is presented, taking into account the two variable-pitch steel blades of the rotor, the drive train, power generation/control, the Nacelle structure, and the yaw drive. The major surface elements of the WTG are the ground enclosure, the back-up battery system, the step-up transformer, elements of the data system, cabling, area lighting, and tower foundation. The final system weight (rotor, Nacelle, and tower) is expected to be about 650,000 pounds. The WTG will be capable of delivering 1800 kW to the utility grid in a wind-speed above 25 mph.

Advanced Performance Modeling with Combined Passive and Active Monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dovrolis, Constantine; Sim, Alex

2015-04-15

To improve the efficiency of resource utilization and scheduling of scientific data transfers on high-speed networks, the "Advanced Performance Modeling with combined passive and active monitoring" (APM) project investigates and models a general-purpose, reusable and expandable network performance estimation framework. The predictive estimation model and the framework will be helpful in optimizing the performance and utilization of networks as well as sharing resources with predictable performance for scientific collaborations, especially in data intensive applications. Our prediction model utilizes historical network performance information from various network activity logs as well as live streaming measurements from network peering devices. Historical network performancemore » information is used without putting extra load on the resources by active measurement collection. Performance measurements collected by active probing is used judiciously for improving the accuracy of predictions.« less

Fractional Order Modeling of Atmospheric Turbulence - A More Accurate Modeling Methodology for Aero Vehicles

NASA Technical Reports Server (NTRS)

Kopasakis, George

2014-01-01

The presentation covers a recently developed methodology to model atmospheric turbulence as disturbances for aero vehicle gust loads and for controls development like flutter and inlet shock position. The approach models atmospheric turbulence in their natural fractional order form, which provides for more accuracy compared to traditional methods like the Dryden model, especially for high speed vehicle. The presentation provides a historical background on atmospheric turbulence modeling and the approaches utilized for air vehicles. This is followed by the motivation and the methodology utilized to develop the atmospheric turbulence fractional order modeling approach. Some examples covering the application of this method are also provided, followed by concluding remarks.

Evaluation of routing and scheduling considerations for possible future commercial hypersonic transport aircraft

NASA Technical Reports Server (NTRS)

Feir, J. B.

1974-01-01

Travel markets which would be served by high speed commercial transport aircraft and the ability of the airlines to schedule and route the aircraft in a way that would achieve good daily utilization and productivity are examined. The following areas are considered: (1) identification of the major long-haul city pairs that would most likely demand nonstop service; (2) selection of flight tracks observing alternative sonic boom restrictions; (3) estimation of flight times for all city pairs for the various sonic boom constraints; (4) impact of airport curfews on possible departure and arrival schedules; (5) projection of passenger traffic volumes on the selected city pairs; and (6) potential daily utilization and aircraft productivity.

Frequency Domain Ultrasound Waveform Tomography: Breast Imaging Using a Ring Transducer

PubMed Central

Sandhu, G Y; Li, C; Roy, O; Schmidt, S; Duric, N

2016-01-01

Application of the frequency domain acoustic wave equation on data acquired from ultrasound tomography scans is shown to yield high resolution sound speed images on the order of the wavelength of the highest reconstructed frequency. Using a signal bandwidth of 0.4–1 MHz and an average sound speed of 1500 m/s, the resolution is approximately 1.5 mm. The quantitative sound speed values and morphology provided by these images have the potential to inform diagnosis and classification of breast disease. In this study, we present the formalism, practical application, and in vivo results of waveform tomography applied to breast data gathered by two different ultrasound tomography scanners that utilize ring transducers. The formalism includes a review of frequency domain modeling of the wave equation using finite difference operators as well as a review of the gradient descent method for the iterative reconstruction scheme. It is shown that the practical application of waveform tomography requires an accurate starting model, careful data processing, and a method to gradually incorporate higher frequency information into the sound speed reconstruction. Following these steps resulted in high resolution quantitative sound speed images of the breast. These images show marked improvement relative to commonly used ray tomography reconstruction methods. The robustness of the method is demonstrated by obtaining similar results from two different ultrasound tomography devices. We also compare our method to MRI to demonstrate concordant findings. The clinical data used in this work was obtained from a HIPAA compliant clinical study (IRB 040912M1F). PMID:26110909

Two Capacitive Micro-Machined Ultrasonic Transducers for Wind Speed Measurement

PubMed Central

Bui, Gia Thinh; Jiang, Yu-Tsung; Pang, Da-Chen

2016-01-01

This paper presents a new wind speed measurement method using a single capacitive micro-machined ultrasonic transducer (CMUT). The CMUT was arranged perpendicular to the direction of the wind flow, and a reflector was set up a short distance away, facing the CMUT. To reduce the size, weight, cost, and power consumption of conventional ultrasonic anemometers this study proposes two CMUT designs for the measurement of wind speed using either the amplitude of the signal or the time of flight (TOF). Each CMUT with a double array element design can transmit and receive signals in five different operation modes. Experiments showed that the two CMUT designs utilizing the TOF were better than those utilizing the amplitude of the signal for wind speed measurements ranging from 1 m/s to 10 m/s, providing a measurement error of less than 0.2 m/s. These results indicate that the sensitivity of the TOF is independent of the five operation modes. PMID:27271625

Two Capacitive Micro-Machined Ultrasonic Transducers for Wind Speed Measurement.

PubMed

Bui, Gia Thinh; Jiang, Yu-Tsung; Pang, Da-Chen

2016-06-02

This paper presents a new wind speed measurement method using a single capacitive micro-machined ultrasonic transducer (CMUT). The CMUT was arranged perpendicular to the direction of the wind flow, and a reflector was set up a short distance away, facing the CMUT. To reduce the size, weight, cost, and power consumption of conventional ultrasonic anemometers this study proposes two CMUT designs for the measurement of wind speed using either the amplitude of the signal or the time of flight (TOF). Each CMUT with a double array element design can transmit and receive signals in five different operation modes. Experiments showed that the two CMUT designs utilizing the TOF were better than those utilizing the amplitude of the signal for wind speed measurements ranging from 1 m/s to 10 m/s, providing a measurement error of less than 0.2 m/s. These results indicate that the sensitivity of the TOF is independent of the five operation modes.

The Role of Power Fluctuations in the Preference of Diagonal vs. Double Poling Sub-Technique at Different Incline-Speed Combinations in Elite Cross-Country Skiers

PubMed Central

Dahl, Christine; Sandbakk, Øyvind; Danielsen, Jørgen; Ettema, Gertjan

2017-01-01

In classical cross-country skiing, diagonal stride (DIA) is the major uphill sub-technique, while double poling (DP) is used on relatively flat terrain. Although, the dependence of incline and speed on the preference of either sub-technique seems clearly established, the mechanisms behind these preferences are not clear. Therefore, the purpose of this study was to compare kinetics and energy consumption in DP and DIA at the same submaximal workload in cross-country skiing under two different incline-speed combinations. We compared kinetics and physiological responses in DP and DIA at the same submaximal workload (≈200 W) under two different incline-speed conditions, (5%—12.5 km h−1 vs. 12%—6.5 km h−1) where DP and DIA were expected to be preferred, respectively. Fifteen elite male cross-country skiers performed four separate 6.5-min roller skiing sessions on a treadmill at these two conditions using DP and DIA during which physiological variables, rate of perceived exertion (RPE) and kinetics, including power fluctuations, were recorded. At 12% incline, DIA resulted in lower physiological response (e.g., heart rate) and RPE, and higher gross efficiency than DP, whereas at 5% incline these variables favored DP (P < 0.05). The skiers' preference for sub-technique (13 preferred DIA at 12% incline; all 15 preferred DP at 5% incline) was in accordance with these results. Fluctuation in instantaneous power was lowest in the preferred sub-technique at each condition (P < 0.05). Preference for DP at 5% incline (high speed) is most likely because the speed is too high for effective ski thrust in DIA, which is reflected in high power fluctuations. The mechanism for preference of DIA at 12% incline is not indicated directly by the current data set showing only small differences in power fluctuations between DIA and DP. Apart from the low speed allowing ski thrust, we suggest that restricted ability to utilize the body's mechanical energy as well as the use of arms in DP play an important role. PMID:28270769

The Role of Power Fluctuations in the Preference of Diagonal vs. Double Poling Sub-Technique at Different Incline-Speed Combinations in Elite Cross-Country Skiers.

PubMed

Dahl, Christine; Sandbakk, Øyvind; Danielsen, Jørgen; Ettema, Gertjan

2017-01-01

In classical cross-country skiing, diagonal stride (DIA) is the major uphill sub-technique, while double poling (DP) is used on relatively flat terrain. Although, the dependence of incline and speed on the preference of either sub-technique seems clearly established, the mechanisms behind these preferences are not clear. Therefore, the purpose of this study was to compare kinetics and energy consumption in DP and DIA at the same submaximal workload in cross-country skiing under two different incline-speed combinations. We compared kinetics and physiological responses in DP and DIA at the same submaximal workload (≈200 W) under two different incline-speed conditions, (5%-12.5 km h -1 vs. 12%-6.5 km h -1 ) where DP and DIA were expected to be preferred, respectively. Fifteen elite male cross-country skiers performed four separate 6.5-min roller skiing sessions on a treadmill at these two conditions using DP and DIA during which physiological variables, rate of perceived exertion ( RPE ) and kinetics, including power fluctuations, were recorded. At 12% incline, DIA resulted in lower physiological response (e.g., heart rate) and RPE , and higher gross efficiency than DP, whereas at 5% incline these variables favored DP ( P < 0.05). The skiers' preference for sub-technique (13 preferred DIA at 12% incline; all 15 preferred DP at 5% incline) was in accordance with these results. Fluctuation in instantaneous power was lowest in the preferred sub-technique at each condition ( P < 0.05). Preference for DP at 5% incline (high speed) is most likely because the speed is too high for effective ski thrust in DIA, which is reflected in high power fluctuations. The mechanism for preference of DIA at 12% incline is not indicated directly by the current data set showing only small differences in power fluctuations between DIA and DP. Apart from the low speed allowing ski thrust, we suggest that restricted ability to utilize the body's mechanical energy as well as the use of arms in DP play an important role.

High Speed Photographic Analysis Of Railgun Plasmas

NASA Astrophysics Data System (ADS)

Macintyre, I. B.

1985-02-01

Various experiments are underway at the Materials Research Laboratories, Australian Department of Defence, to develop a theory for the behaviour and propulsion action of plasmas in rail guns. Optical recording and imaging devices, with their low vulnerability to the effects of magnetic and electric fields present in the vicinity of electromagnetic launchers, have proven useful as diagnostic tools. This paper describes photoinstrumentation systems developed to provide visual qualitative assessment of the behaviour of plasma travelling along the bore of railgun launchers. In addition, a quantitative system is incorporated providing continuous data (on a microsecond time scale) of (a) Length of plasma during flight along the launcher bore. (b) Velocity of plasma. (c) Distribution of plasma with respect to time after creation. (d) Plasma intensity profile as it travels along the launcher bore. The evolution of the techniques used is discussed. Two systems were employed. The first utilized a modified high speed streak camera to record the light emitted from the plasma, through specially prepared fibre optic cables. The fibre faces external to the bore were then imaged onto moving film. The technique involved the insertion of fibres through the launcher body to enable the plasma to be viewed at discrete positions as it travelled along the launcher bore. Camera configuration, fibre optic preparation and experimental results are outlined. The second system utilized high speed streak and framing photography in conjunction with accurate sensitometric control procedures on the recording film. The two cameras recorded the plasma travelling along the bore of a specially designed transparent launcher. The streak camera, fitted with a precise slit size, recorded a streak image of the upper brightness range of the plasma as it travelled along the launcher's bore. The framing camera recorded an overall view of the launcher and the plasma path, to the maximum possible, governed by the film's ability to reproduce the plasma's brightness range. The instrumentation configuration, calibration, and film measurement using microdensitometer scanning techniques to evaluate inbore plasma behaviour, are also presented.

Enabling high speed friction stir welding of aluminum tailor welded blanks

NASA Astrophysics Data System (ADS)

Hovanski, Yuri

Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding (FSW) has traditionally been applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translate to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum FSW components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability using a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.

High-Speed Friction-Stir Welding to Enable Aluminum Tailor-Welded Blanks

NASA Astrophysics Data System (ADS)

Hovanski, Yuri; Upadhyay, Piyush; Carsley, John; Luzanski, Tom; Carlson, Blair; Eisenmenger, Mark; Soulami, Ayoub; Marshall, Dustin; Landino, Brandon; Hartfield-Wunsch, Susan

2015-05-01

Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and they have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high volumes. While friction-stir welding (FSW) has been traditionally applied at linear velocities less than 1 m/min, high-volume production applications demand the process be extended to higher velocities more amenable to cost-sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low-to-moderate welding velocities do not directly translate to high-speed linear FSW. Therefore, to facilitate production of high-volume aluminum FSW components, parameters were developed with a minimum welding velocity of 3 m/min. With an emphasis on weld quality, welded blanks were evaluated for postweld formability using a combination of numerical and experimental methods. An evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum TWBs, which provided validation of the numerical and experimental analysis of laboratory-scale tests.

Distributed flow sensing for closed-loop speed control of a flexible fish robot.

PubMed

Zhang, Feitian; Lagor, Francis D; Yeo, Derrick; Washington, Patrick; Paley, Derek A

2015-10-23

Flexibility plays an important role in fish behavior by enabling high maneuverability for predator avoidance and swimming in turbulent flow. This paper presents a novel flexible fish robot equipped with distributed pressure sensors for flow sensing. The body of the robot is molded from soft, hyperelastic material, which provides flexibility. Its Joukowski-foil shape is conducive to modeling the fluid analytically. A quasi-steady potential-flow model is adopted for real-time flow estimation, whereas a discrete-time vortex-shedding flow model is used for higher-fidelity simulation. The dynamics for the flexible fish robot yield a reduced model for one-dimensional swimming. A recursive Bayesian filter assimilates pressure measurements to estimate flow speed, angle of attack, and foil camber. The closed-loop speed-control strategy combines an inverse-mapping feedforward controller based on an average model derived for periodic actuation of angle-of-attack and a proportional-integral feedback controller utilizing the estimated flow information. Simulation and experimental results are presented to show the effectiveness of the estimation and control strategy. The paper provides a systematic approach to distributed flow sensing for closed-loop speed control of a flexible fish robot by regulating the flapping amplitude.

Progress Toward Affordable High Fidelity Combustion Simulations Using Filtered Density Functions for Hypersonic Flows in Complex Geometries

NASA Technical Reports Server (NTRS)

Drozda, Tomasz G.; Quinlan, Jesse R.; Pisciuneri, Patrick H.; Yilmaz, S. Levent

2012-01-01

Significant progress has been made in the development of subgrid scale (SGS) closures based on a filtered density function (FDF) for large eddy simulations (LES) of turbulent reacting flows. The FDF is the counterpart of the probability density function (PDF) method, which has proven effective in Reynolds averaged simulations (RAS). However, while systematic progress is being made advancing the FDF models for relatively simple flows and lab-scale flames, the application of these methods in complex geometries and high speed, wall-bounded flows with shocks remains a challenge. The key difficulties are the significant computational cost associated with solving the FDF transport equation and numerically stiff finite rate chemistry. For LES/FDF methods to make a more significant impact in practical applications a pragmatic approach must be taken that significantly reduces the computational cost while maintaining high modeling fidelity. An example of one such ongoing effort is at the NASA Langley Research Center, where the first generation FDF models, namely the scalar filtered mass density function (SFMDF) are being implemented into VULCAN, a production-quality RAS and LES solver widely used for design of high speed propulsion flowpaths. This effort leverages internal and external collaborations to reduce the overall computational cost of high fidelity simulations in VULCAN by: implementing high order methods that allow reduction in the total number of computational cells without loss in accuracy; implementing first generation of high fidelity scalar PDF/FDF models applicable to high-speed compressible flows; coupling RAS/PDF and LES/FDF into a hybrid framework to efficiently and accurately model the effects of combustion in the vicinity of the walls; developing efficient Lagrangian particle tracking algorithms to support robust solutions of the FDF equations for high speed flows; and utilizing finite rate chemistry parametrization, such as flamelet models, to reduce the number of transported reactive species and remove numerical stiffness. This paper briefly introduces the SFMDF model (highlighting key benefits and challenges), and discusses particle tracking for flows with shocks, the hybrid coupled RAS/PDF and LES/FDF model, flamelet generated manifolds (FGM) model, and the Irregularly Portioned Lagrangian Monte Carlo Finite Difference (IPLMCFD) methodology for scalable simulation of high-speed reacting compressible flows.

Ultrafast Pulse Generation in an Organic Nanoparticle-Array Laser.

PubMed

Daskalakis, Konstantinos S; Väkeväinen, Aaro I; Martikainen, Jani-Petri; Hakala, Tommi K; Törmä, Päivi

2018-04-11

Nanoscale coherent light sources offer potentially ultrafast modulation speeds, which could be utilized for novel sensors and optical switches. Plasmonic periodic structures combined with organic gain materials have emerged as promising candidates for such nanolasers. Their plasmonic component provides high intensity and ultrafast nanoscale-confined electric fields, while organic gain materials offer fabrication flexibility and a low acquisition cost. Despite reports on lasing in plasmonic arrays, lasing dynamics in these structures have not been experimentally studied yet. Here we demonstrate, for the first time, an organic dye nanoparticle-array laser with more than a 100 GHz modulation bandwidth. We show that the lasing modulation speed can be tuned by the array parameters. Accelerated dynamics is observed for plasmonic lasing modes at the blue side of the dye emission.

The Feasibility of Railgun Horizontal-Launch Assist

NASA Technical Reports Server (NTRS)

Youngquist, Robert C.; Cox, Robert B.

2011-01-01

Railguns typically operate for a few milliseconds, supplying thousands of G's of acceleration to a small projectile, resulting in exceptional speeds. This paper argues through analysis and experiment, that this "standard" technology can be modified to provide 2-3 G's acceleration to a relatively heavy launch vehicle for a time period exceeding several seconds, yielding a launch assist velocity in excess of Mach 1. The key insight here is that an efficient rail gun operates at a speed approximately given by the system resistance divided by the inductance gradient, which can be tailored because recent MOSFET and ultra-capacitor advances allow very low total power supply resistances with high capacitance and augmented railgun architectures provide a scalable inductance gradient. Consequently, it should now be possible to construct a horizontal launch assist system utilizing railgun based architecture.

Portable emergency telemedicine system over wireless broadband and 3G networks.

PubMed

Hong, SungHye; Kim, SangYong; Kim, JungChae; Lim, DongKyu; Jung, SeokMyung; Kim, DongKeun; Yoo, Sun K

2009-01-01

The telemedicine system aims at monitoring patients remotely without limit in time and space. However the existing telemedicine systems exchange medical information simply in a specified location. Due to increasing speed in processing data and expanding bandwidth of wireless networks, it is possible to perform telemedicine services on personal digital assistants (PDA). In this paper, a telemedicine system on PDA was developed using wideband mobile networks such as Wi-Fi, HSDPA, and WiBro for high speed bandwidths. This system enables to utilize and exchange variety and reliable patient information of video, biosignals, chatting messages, and triage data. By measuring bandwidths of individual data of the system over wireless networks, and evaluating the performance of this system using PDA, we demonstrated the feasibility of the designed portable emergency telemedicine system.

Low cost composite materials for wind energy conversion systems

NASA Technical Reports Server (NTRS)

Weingart, O.

1980-01-01

A winding process utilizing a low-cost E-glass fabric called transverse-filament tape for low-cost production of wind turbine generators (WTG) is described. The process can be carried out continuously at high speed to produce large one-piece parts with tapered wall thicknesses on a tapered mandrel. It is being used to manufacture blades for the NASA/DOE 200-ft-diameter MOD-1 WTG and Rockwell/DOE 40-kW small wind energy conversion system (SWECS).

On fast carry select adders

NASA Technical Reports Server (NTRS)

Shamanna, M.; Whitaker, S.

1992-01-01

This paper presents an architecture for a high-speed carry select adder with very long bit lengths utilizing a conflict-free bypass scheme. The proposed scheme has almost half the number of transistors and is faster than a conventional carry select adder. A comparative study is also made between the proposed adder and a Manchester carry chain adder which shows that the proposed scheme has the same transistor count, without suffering any performance degradation, compared to the Manchester carry chain adder.

Use of a thermophotovoltaic generator in a hybrid electric vehicle

NASA Astrophysics Data System (ADS)

Morrison, Orion; Seal, Michael; West, Edward; Connelly, William

1999-03-01

Viking 29 is the World's first thermophotovoltaic (TPV) powered automobile. The prototype was funded by the Department of Energy and designed and built by students and faculty at the Vehicle Research Institute (VRI) at Western Washington University. Viking 29 is a series hybrid electric vehicle that utilizes TPV generators to charge its battery pack. Acceleration, speed, and handling compare to modern high performance sports cars, while emissions are cleaner than current internal combustion engine vehicles.

Integrating TV/digital data spectrograph system

NASA Technical Reports Server (NTRS)

Duncan, B. J.; Fay, T. D.; Miller, E. R.; Wamsteker, W.; Brown, R. M.; Neely, P. L.

1975-01-01

A 25-mm vidicon camera was previously modified to allow operation in an integration mode for low-light-level astronomical work. The camera was then mated to a low-dispersion spectrograph for obtaining spectral information in the 400 to 750 nm range. A high speed digital video image system was utilized to digitize the analog video signal, place the information directly into computer-type memory, and record data on digital magnetic tape for permanent storage and subsequent analysis.

Evaluation and Improvement of Eddy Current Position Sensors in Magnetically Suspended Flywheel Systems

NASA Technical Reports Server (NTRS)

Dever, Timothy P.; Palazzolo, Alan B.; Thomas, Erwin M., III; Jansen, Ralph H.; McLallin, Kerry (Technical Monitor); Soeder, James (Technical Monitor)

2001-01-01

Eddy current position sensor performance is evaluated for use in a high-speed flywheel development system. The flywheel utilizes a five axis active magnetic bearing system. The eddy current sensors are used for position feedback for the bearing controller. Measured characteristics include sensitivity to multiple target materials and susceptibility to noise from the magnetic bearings and from sensor-to-sensor crosstalk. Improvements in axial sensor configuration and techniques for noise reduction are described.

Objective Operational Utilization of Satellite Microwave Scatterometer Observations of Tropical Cyclones

NASA Technical Reports Server (NTRS)

Cardone, Vincent J.; Cox, Andrew T.

2000-01-01

This study has demonstrated that high-resolution scatterometer measurements in tropical cyclones and other high-marine surface wind regimes may be retrieved accurately for wind speeds up to about 35 mls (1-hour average at 10 m) when the scatterometer data are processed through a revised geophysical model function, and a spatial adaptive algorithm is applied which utilizes the fact that wind direction is so tightly constrained in tile inner core of severe marine storms that wind direction may be prescribed from conventional data. This potential is demonstrated through case studies with NSCAT data in a severe West Pacific Typhoon (Violet, 1996) and an intense North Atlantic hurricane (Lili, 1996). However, operational scatterometer winds from NSCAT and QuickScat in hurricanes and severe winter storms are biased low in winds above 25 m/s. We have developed an inverse model to specify the entire surface wind field about a tropical cyclone from operational QuickScat scatterometer measurements within 150 nm of a storm center with the restriction that only wind speeds up to 20 m/s are used until improved model function are introduced. The inverse model is used to specify the wind field over the entire life-cycle of Hurricane Floyd (1999) for use to drive an ocean wave model. The wind field compares very favorably with wind fields developed from the copious aircraft flight level winds obtained in this storm.

Horizontal-axis clothes washer market poised for expansion

DOE Office of Scientific and Technical Information (OSTI.GOV)

George, K.L.

1994-12-31

The availability of energy- and water-efficient horizontal-axis washing machines in the North American market is growing, as US and European manufacturers position for an expected long-term market shift toward horizontal-axis (H-axis) technology. Four of the five major producers of washing machines in the US are developing or considering new H-axis models. New entrants, including US-based Staber Industries and several European manufacturers, are also expected to compete in this market. The intensified interest in H-axis technology is partly driven by speculation that new US energy efficiency standards, to be proposed in 1996 and implemented in 1999, will effectively mandate H-axis machines.more » H-axis washers typically use one-third to two-thirds less energy, water, and detergent than vertical-axis machines. Some models also reduce the energy needed to dry the laundry, since their higher spin speeds extract more water than is typical with vertical-axis designs. H-axis washing machines are the focus of two broadly-based efforts to support coordinated research and incentive programs by electric, gas, and water utilities: The High-Efficiency Laundry Metering/Marketing Analysis (THELMA), and the Consortium for Energy Efficiency (CEE) High-Efficiency Clothes Washer Initiative. These efforts may help to pave the way for new types of marketing partnerships among utilities and other parties that could help to speed adoption of H-axis washers.« less

A Rotational Gyroscope with a Water-Film Bearing Based on Magnetic Self-Restoring Effect.

PubMed

Chen, Dianzhong; Liu, Xiaowei; Zhang, Haifeng; Li, Hai; Weng, Rui; Li, Ling; Rong, Wanting; Zhang, Zhongzhao

2018-01-31

Stable rotor levitation is a challenge for rotational gyroscopes (magnetically suspended gyroscopes (MSG) and electrostatically suspended gyroscopes (ESG)) with a ring- or disk-shaped rotor, which restricts further improvement of gyroscope performance. In addition, complicated pick-up circuits and feedback control electronics propose high requirement on fabrication technology. In the proposed gyroscope, a ball-disk shaped rotor is supported by a water-film bearing, formed by centrifugal force to deionized water at the cavity of the lower supporting pillar. Water-film bearing provides stable mechanical support, without the need for complicated electronics and control system for rotor suspension. To decrease sliding friction between the rotor ball and the water-film bearing, a supherhydrophobic surface (SHS) with nano-structures is fabricated on the rotor ball, resulting in a rated spinning speed increase of 12.4% (under the same driving current). Rotor is actuated by the driving scheme of brushless direct current motor (BLDCM). Interaction between the magnetized rotor and the magnetic-conducted stator produces a sinusoidal rotor restoring torque, amplitude of which is proportional to the rotor deflection angle inherently. Utilization of this magnetic restoring effect avoids adding of a high amplitude voltage for electrostatic feedback, which may cause air breakdown. Two differential capacitance pairs are utilized to measure input angular speeds at perpendicular directions of the rotor plane. The bias stability of the fabricated gyroscope is as low as 0.5°/h.

The combined risk of extreme tropical cyclone winds and storm surges along the U.S. Gulf of Mexico Coast

NASA Astrophysics Data System (ADS)

Trepanier, J. C.; Yuan, J.; Jagger, T. H.

2017-03-01

Tropical cyclones, with their nearshore high wind speeds and deep storm surges, frequently strike the United States Gulf of Mexico coastline influencing millions of people and disrupting offshore economic activities. The combined risk of occurrence of tropical cyclone nearshore wind speeds and storm surges is assessed at 22 coastal cities throughout the United States Gulf of Mexico. The models used are extreme value copulas fitted with margins defined by the generalized Pareto distribution or combinations of Weibull, gamma, lognormal, or normal distributions. The statistical relationships between the nearshore wind speed and storm surge are provided for each coastal city prior to the copula model runs using Spearman's rank correlations. The strongest significant relationship between the nearshore wind speed and storm surge exists at Shell Beach, LA (ρ = 0.67), followed by South Padre Island, TX (ρ = 0.64). The extreme value Archimedean copula models for each city then provide return periods for specific nearshore wind speed and storm surge pairs. Of the 22 cities considered, Bay St. Louis, MS, has the shortest return period for a tropical cyclone with at least a 50 ms-1 nearshore wind speed and a 3 m surge (19.5 years, 17.1-23.5). The 90% confidence intervals are created by recalculating the return periods for a fixed set of wind speeds and surge levels using 100 samples of the model parameters. The results of this study can be utilized by policy managers and government officials concerned with coastal populations and economic activity in the Gulf of Mexico.

Real-time sound speed correction using golden section search to enhance ultrasound imaging quality

NASA Astrophysics Data System (ADS)

Yoon, Chong Ook; Yoon, Changhan; Yoo, Yangmo; Song, Tai-Kyong; Chang, Jin Ho

2013-03-01

In medical ultrasound imaging, high-performance beamforming is important to enhance spatial and contrast resolutions. A modern receive dynamic beamfomer uses a constant sound speed that is typically assumed to 1540 m/s in generating receive focusing delays [1], [2]. However, this assumption leads to degradation of spatial and contrast resolutions particularly when imaging obese patients or breast since the sound speed is significantly lower than the assumed sound speed [3]; the true sound speed in the fatty tissue is around 1450 m/s. In our previous study, it was demonstrated that the modified nonlinear anisotropic diffusion is capable of determining an optimal sound speed and the proposed method is a useful tool to improve ultrasound image quality [4], [5]. In the previous study, however, we utilized at least 21 iterations to find an optimal sound speed, which may not be viable for real-time applications. In this paper, we demonstrates that the number of iterations can be dramatically reduced using the GSS(golden section search) method with a minimal error. To evaluate performances of the proposed method, in vitro experiments were conducted with a tissue mimicking phantom. To emulate a heterogeneous medium, the phantom was immersed in the water. From the experiments, the number of iterations was reduced from 21 to 7 with GSS method and the maximum error of the lateral resolution between direct and GSS was less than 1%. These results indicate that the proposed method can be implemented in real time to improve the image quality in the medical ultrasound imaging.

Effect of Variation of Speed Limits on Intercity Bus Fuel Consumption, Coach and Driver Utilization, and Corporate Profitability

DOT National Transportation Integrated Search

1975-11-01

The effect of speed limit and passenger load on fuel consumption was determined using actual intercity buses with simulated passenger loads over different types of terrain. In addition to road tests, laboratory type measurements were made on four int...

Assessment of bioresorbable scaffold with a novel high-definition 60 MHz IVUS imaging system: Comparison with 40-MHz IVUS referenced to optical coherence tomography.

PubMed

Okada, Kozo; Kitahara, Hideki; Mitsutake, Yoshiaki; Tanaka, Shigemitsu; Kimura, Takumi; Yock, Paul G; Fitzgerald, Peter J; Ikeno, Fumiaki; Honda, Yasuhiro

2018-04-01

In vivo assessment of bioresorbable scaffold (BRS) is of growing clinical interest. The novel 60MHz high-definition intravascular ultrasound (HD-IVUS) has been developed to overcome the limitations of conventional 40 MHz IVUS. This study aimed to evaluate the performance and limitations of 60 MHz HD-IVUS compared with 40 MHz IVUS with respect to polymeric-strut visualization, quantitative and qualitative analysis, and feasibility of high-speed pullback in the assessment of BRS. In a bench-test model, 361 struts were analyzed to evaluate the influence of ultrasound-beam angles and proximity of adjacent struts on IVUS visualization of BRS struts. Various settings were created by deforming the BRS and positioning the transducer offcenter. In an in vivo swine coronary model, scaffold and lumen areas, degree of visible external elastic membrane, incomplete strut apposition, and strut fracture were evaluated in 59 matched cross-sections obtained at conventional (0.5 mm/sec) and high speed (10 mm/sec) pullbacks. Both studies utilized optical coherence tomography (OCT) as reference. Overall, 60 MHz HD-IVUS demonstrated significantly improved visualization of polymeric struts compared with 40 MHz IVUS (well-visualized: 84.5% vs 62.3%, not visible: 4.4% vs 13.9%, respectively. P < 0.001), which was less affected by the beam angle and adjacent strut proximity. In the in vivo model, 60-MHz HD-IVUS showed better agreement of area measurements and strut abnormalities with OCT than 40 MHz IVUS. These findings were also confirmed on high-speed pullback images of 60 MHz HD-IVUS. As referenced to OCT, this study showed superiority of 60 MHz HD-IVUS over 40 MHz IVUS in the assessment of BRS with feasibility of high-speed pullback imaging. © 2017 Wiley Periodicals, Inc.

Eight Weeks of Strength and Power Training Improves Club Head Speed in Collegiate Golfers.

PubMed

Oranchuk, Dustin J; Mannerberg, Jason M; Robinson, Tracey L; Nelson, Megan C

2018-02-14

Club head speed (CHS) is a major determinant of drive distance, a key component of golf performance. The purpose of this study was to determine the indirect effects of an eight-week strength and power program on CHS. Twelve (6 male, 6 female) NCAA Division II golfers (20.3±1.5 years) randomly assigned to an intervention or control group, underwent either a periodized strength and power program consisting of high-load barbell movements or a bodyweight and rotational movement focused resistance training program. Outcomes were CHS, countermovement jump (CMJ) height, and 1RM back squat (BS), power clean (PC), and deadlift (DL). Dependent t-tests were utilized to assess differences in outcome variables pre-to-post for each group, independent t-tests were utilized to assess differences between groups, and Pearson correlations were utilized to assess associations between CHS and outcome variables. On average, the intervention group experienced improvements in all outcome variables except peak CHS (p=0.60); the control group displayed no changes in any outcome variable except a decrease in average CHS (p=0.028). Compared to the control group, the intervention group experienced greater improvements in average CHS, BS, PC, and average and peak CMJ height (p<0.05). Additionally, CHS had large associations with PC (r=0.70, p=0.012), BS (r=0.64, p=0.025), DL (r=0.54, p=0.068) and CMJ (r=0.73, p=0.007). These results suggest improving muscular strength and power by increasing PC, BS, and CMJ is associated with increased CHS in collegiate golfers. Integrating a high-load, barbell-focused strength and power program may be beneficial for improving CHS and indirectly, golf performance.

Making Ceramic Components For Advanced Aircraft Engines

NASA Technical Reports Server (NTRS)

Franklin, J. E.; Ezis, A.

1994-01-01

Lightweight, oxidation-resistant silicon nitride components containing intricate internal cooling and hydraulic passages and capable of withstanding high operating temperatures made by ceramic-platelet technology. Used to fabricate silicon nitride test articles of two types: components of methane-cooled regenerator for air turbo ramjet engine and components of bipropellant injector for rocket engine. Procedures for development of more complex and intricate components established. Technology has commercial utility in automotive, aircraft, and environmental industries for manufacture of high-temperature components for use in regeneration of fuels, treatment of emissions, high-temperature combustion devices, and application in which other high-temperature and/or lightweight components needed. Potential use in fabrication of combustors and high-temperature acoustic panels for suppression of noise in future high-speed aircraft.

Diaphragmless shock wave generators for industrial applications of shock waves

NASA Astrophysics Data System (ADS)

Hariharan, M. S.; Janardhanraj, S.; Saravanan, S.; Jagadeesh, G.

2011-06-01

The prime focus of this study is to design a 50 mm internal diameter diaphragmless shock tube that can be used in an industrial facility for repeated loading of shock waves. The instantaneous rise in pressure and temperature of a medium can be used in a variety of industrial applications. We designed, fabricated and tested three different shock wave generators of which one system employs a highly elastic rubber membrane and the other systems use a fast acting pneumatic valve instead of conventional metal diaphragms. The valve opening speed is obtained with the help of a high speed camera. For shock generation systems with a pneumatic cylinder, it ranges from 0.325 to 1.15 m/s while it is around 8.3 m/s for the rubber membrane. Experiments are conducted using the three diaphragmless systems and the results obtained are analyzed carefully to obtain a relation between the opening speed of the valve and the amount of gas that is actually utilized in the generation of the shock wave for each system. The rubber membrane is not suitable for industrial applications because it needs to be replaced regularly and cannot withstand high driver pressures. The maximum shock Mach number obtained using the new diaphragmless system that uses the pneumatic valve is 2.125 ± 0.2%. This system shows much promise for automation in an industrial environment.

Interferometric imaging of acoustical phenomena using high-speed polarization camera and 4-step parallel phase-shifting technique

NASA Astrophysics Data System (ADS)

Ishikawa, K.; Yatabe, K.; Ikeda, Y.; Oikawa, Y.; Onuma, T.; Niwa, H.; Yoshii, M.

2017-02-01

Imaging of sound aids the understanding of the acoustical phenomena such as propagation, reflection, and diffraction, which is strongly required for various acoustical applications. The imaging of sound is commonly done by using a microphone array, whereas optical methods have recently been interested due to its contactless nature. The optical measurement of sound utilizes the phase modulation of light caused by sound. Since light propagated through a sound field changes its phase as proportional to the sound pressure, optical phase measurement technique can be used for the sound measurement. Several methods including laser Doppler vibrometry and Schlieren method have been proposed for that purpose. However, the sensitivities of the methods become lower as a frequency of sound decreases. In contrast, since the sensitivities of the phase-shifting technique do not depend on the frequencies of sounds, that technique is suitable for the imaging of sounds in the low-frequency range. The principle of imaging of sound using parallel phase-shifting interferometry was reported by the authors (K. Ishikawa et al., Optics Express, 2016). The measurement system consists of a high-speed polarization camera made by Photron Ltd., and a polarization interferometer. This paper reviews the principle briefly and demonstrates the high-speed imaging of acoustical phenomena. The results suggest that the proposed system can be applied to various industrial problems in acoustical engineering.

Long-Term Deflection Prediction from Computer Vision-Measured Data History for High-Speed Railway Bridges

PubMed Central

Lee, Jaebeom; Lee, Young-Joo

2018-01-01

Management of the vertical long-term deflection of a high-speed railway bridge is a crucial factor to guarantee traffic safety and passenger comfort. Therefore, there have been efforts to predict the vertical deflection of a railway bridge based on physics-based models representing various influential factors to vertical deflection such as concrete creep and shrinkage. However, it is not an easy task because the vertical deflection of a railway bridge generally involves several sources of uncertainty. This paper proposes a probabilistic method that employs a Gaussian process to construct a model to predict the vertical deflection of a railway bridge based on actual vision-based measurement and temperature. To deal with the sources of uncertainty which may cause prediction errors, a Gaussian process is modeled with multiple kernels and hyperparameters. Once the hyperparameters are identified through the Gaussian process regression using training data, the proposed method provides a 95% prediction interval as well as a predictive mean about the vertical deflection of the bridge. The proposed method is applied to an arch bridge under operation for high-speed trains in South Korea. The analysis results obtained from the proposed method show good agreement with the actual measurement data on the vertical deflection of the example bridge, and the prediction results can be utilized for decision-making on railway bridge maintenance. PMID:29747421

Modified Adaptive Control for Region 3 Operation in the Presence of Wind Turbine Structural Modes

NASA Technical Reports Server (NTRS)

Frost, Susan Alane; Balas, Mark J.; Wright, Alan D.

2010-01-01

Many challenges exist for the operation of wind turbines in an efficient manner that is reliable and avoids component fatigue and failure. Turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, possibly causing component fatigue and failure. Wind turbine manufacturers are highly motivated to reduce component fatigue and failure that can lead to loss of revenue due to turbine down time and maintenance costs. The trend in wind turbine design is toward larger, more flexible turbines that are ideally suited to adaptive control methods due to the complexity and expense required to create accurate models of their dynamic characteristics. In this paper, we design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed horizontal axis wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the excitation of structural modes in the wind turbine. The control objective is accomplished by collectively pitching the turbine blades. The adaptive collective pitch controller for Region 3 was compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller. The adaptive controller will demonstrate the ability to regulate generator speed in Region 3, while accommodating gusts, and reducing the excitation of certain structural modes in the wind turbine.

Process stability during fiber laser-arc hybrid welding of thick steel plates

NASA Astrophysics Data System (ADS)

Bunaziv, Ivan; Frostevarg, Jan; Akselsen, Odd M.; Kaplan, Alexander F. H.

2018-03-01

Thick steel plates are frequently used in shipbuilding, pipelines and other related heavy industries, and are usually joined by arc welding. Deep penetration laser-arc hybrid welding could increase productivity but has not been thoroughly investigated, and is therefore usually limited to applications with medium thickness (5-15 mm) sections. A major concern is process stability, especially when using modern welding consumables such as metal-cored wire and advanced welding equipment. High speed imaging allows direct observation of the process so that process behavior and phenomena can be studied. In this paper, 45 mm thick high strength steel was welded (butt joint double-sided) using the fiber laser-MAG hybrid process utilizing a metal-cored wire without pre-heating. Process stability was monitored under a wide range of welding parameters. It was found that the technique can be used successfully to weld thick sections with appropriate quality when the parameters are optimized. When comparing conventional pulsed and the more advanced cold metal transfer pulse (CMT+P) arc modes, it was found that both can provide high quality welds. CMT+P arc mode can provide more stable droplet transfer over a limited range of travel speeds. At higher travel speeds, an unstable metal transfer mechanism was observed. Comparing leading arc and trailing arc arrangements, the leading arc configuration can provide higher quality welds and more stable processing at longer inter-distances between the heat sources.

Long-Term Deflection Prediction from Computer Vision-Measured Data History for High-Speed Railway Bridges.

PubMed

Lee, Jaebeom; Lee, Kyoung-Chan; Lee, Young-Joo

2018-05-09

Management of the vertical long-term deflection of a high-speed railway bridge is a crucial factor to guarantee traffic safety and passenger comfort. Therefore, there have been efforts to predict the vertical deflection of a railway bridge based on physics-based models representing various influential factors to vertical deflection such as concrete creep and shrinkage. However, it is not an easy task because the vertical deflection of a railway bridge generally involves several sources of uncertainty. This paper proposes a probabilistic method that employs a Gaussian process to construct a model to predict the vertical deflection of a railway bridge based on actual vision-based measurement and temperature. To deal with the sources of uncertainty which may cause prediction errors, a Gaussian process is modeled with multiple kernels and hyperparameters. Once the hyperparameters are identified through the Gaussian process regression using training data, the proposed method provides a 95% prediction interval as well as a predictive mean about the vertical deflection of the bridge. The proposed method is applied to an arch bridge under operation for high-speed trains in South Korea. The analysis results obtained from the proposed method show good agreement with the actual measurement data on the vertical deflection of the example bridge, and the prediction results can be utilized for decision-making on railway bridge maintenance.

REDUCTION OF EMISSIONS FROM A HIGH SPEED FERRY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson,G.; Gautam, M; Clark, N

2003-08-24

Emissions from marine vessels are being scrutinized as a major contributor to the total particulate matter (TPM), oxides of sulfur (SOx) and oxides of nitrogen (NOx) environmental loading. Fuel sulfur control is the key to SOx reduction. Significant reductions in the emissions from on-road vehicles have been achieved in the last decade and the emissions from these vehicles will be reduced by another order of magnitude in the next five years: these improvements have served to emphasize the need to reduce emissions from other mobile sources, including off road equipment, locomotives, and marine vessels. Diesel-powered vessels of interest include oceanmore » going vessels with low- and medium-speed engines, as well as ferries with high speed engines, as discussed below. A recent study examined the use of intake water injection (WIS) and ultra low sulfur diesel (ULSD) to reduce the emissions from a high-speed passenger ferry in southern California. One of the four Detroit Diesel 12V92 two-stroke high speed engines that power the Waverider (operated by SCX, inc.) was instrumented to collect intake airflow, fuel flow, shaft torque, and shaft speed. Engine speed and shaft torque were uniquely linked for given vessel draft and prevailing wind and sea conditions. A raw exhaust gas sampling system was utilized to measure the concentration of NOx, carbon dioxide (CO2), and oxygen (O2) and a mini dilution tunnel sampling a slipstream from the raw exhaust was used to collect TPM on 70 mm filters. The emissions data were processed to yield brake-specific mass results. The system that was employed allowed for redundant data to be collected for quality assurance and quality control. To acquire the data, the Waverider was operated at five different steady state speeds. Three modes were in the open sea off Oceanside, CA, and idle and harbor modes were also used. Data have showed that the use of ULSD along with water injection (WIS) could significantly reduce the emissions of NOx and PM while not affecting fuel consumption or engine performance compared to the baseline marine diesel. The results showed that a nominal 40% reduction in TPM was realized when switching from the marine diesel to the ULSD. A small reduction in NOx was also shown between the marine fuel and the ULSD. The implementation of the WIS showed that NOx was reduced significantly by between 11% and 17%, depending upon the operating condition. With the WIS, the TPM was reduced by a few percentage points, which was close to the confidence in measurement.« less

How animals drink and swim in fluids

NASA Astrophysics Data System (ADS)

Jung, Sunghwan

2011-10-01

Fluids are essential for most living organisms to maintain a healthy body and also serve as a medium in which they locomote. The fluid bulk or interfaces actively interact with biological structures, which produces highly nonlinear, interesting, and complicated dynamical problems. We studied the lapping of cats and the swimming of Paramecia in various fluidic environments. The problem of the cat drinking can be simplified as the competition between inertia and gravity whereas the problem of Paramecium swimming in viscous fluids results from the competition between viscous drag and thrust. The underlying mechanisms are discussed and understood through laboratory experiments utilizing high-speed photography.

A new type of magnetic gimballed momentum wheel and its application to attitude control in space

NASA Astrophysics Data System (ADS)

Murakami, C.; Ohkami, Y.; Okamoto, O.; Nakajima, A.; Inoue, M.; Tsuchiya, J.; Yabu-uchi, K.; Akishita, S.; Kida, T.

A new type of magnetically suspended gimbal momentum wheel utilizing permanent magnets is described. The bearing was composed of four independent thrust actuators which control the rotor thrust position and gimbal angles cooperatively, so that the bearing comes to have a simple mechanism with high reliability and light weight. The high speed instability problem due to the internal damping was easily overcome by introducing anisotropic radial stiffness. A momentum flywheel with the 3-axis controlled magnetic bearing displays good performance for attitude control of satellite with biased momentum.

Apparatus and method for operating internal combustion engines from variable mixtures of gaseous fuels

DOEpatents

Heffel, James W [Lake Matthews, CA; Scott, Paul B [Northridge, CA; Park, Chan Seung [Yorba Linda, CA

2011-11-01

An apparatus and method for utilizing any arbitrary mixture ratio of multiple fuel gases having differing combustion characteristics, such as natural gas and hydrogen gas, within an internal combustion engine. The gaseous fuel composition ratio is first sensed, such as by thermal conductivity, infrared signature, sound propagation speed, or equivalent mixture differentiation mechanisms and combinations thereof which are utilized as input(s) to a "multiple map" engine control module which modulates selected operating parameters of the engine, such as fuel injection and ignition timing, in response to the proportions of fuel gases available so that the engine operates correctly and at high efficiency irrespective of the gas mixture ratio being utilized. As a result, an engine configured according to the teachings of the present invention may be fueled from at least two different fuel sources without admixing constraints.

Apparatus and method for operating internal combustion engines from variable mixtures of gaseous fuels

DOEpatents

Heffel, James W.; Scott, Paul B.

2003-09-02

An apparatus and method for utilizing any arbitrary mixture ratio of multiple fuel gases having differing combustion characteristics, such as natural gas and hydrogen gas, within an internal combustion engine. The gaseous fuel composition ratio is first sensed, such as by thermal conductivity, infrared signature, sound propagation speed, or equivalent mixture differentiation mechanisms and combinations thereof which are utilized as input(s) to a "multiple map" engine control module which modulates selected operating parameters of the engine, such as fuel injection and ignition timing, in response to the proportions of fuel gases available so that the engine operates correctly and at high efficiency irrespective of the gas mixture ratio being utilized. As a result, an engine configured according to the teachings of the present invention may be fueled from at least two different fuel sources without admixing constraints.

Calculus migration characterization during Ho:YAG laser lithotripsy by high-speed camera using suspended pendulum method.

PubMed

Zhang, Jian James; Rajabhandharaks, Danop; Xuan, Jason Rongwei; Chia, Ray W J; Hasenberg, Thomas

2017-07-01

Calculus migration is a common problem during ureteroscopic laser lithotripsy procedure to treat urolithiasis. A conventional experimental method to characterize calculus migration utilized a hosting container (e.g., a "V" grove or a test tube). These methods, however, demonstrated large variation and poor detectability, possibly attributed to the friction between the calculus and the container on which the calculus was situated. In this study, calculus migration was investigated using a pendulum model suspended underwater to eliminate the aforementioned friction. A high-speed camera was used to study the movement of the calculus which covered zero order (displacement), first order (speed), and second order (acceleration). A commercialized, pulsed Ho:YAG laser at 2.1 μm, a 365-μm core diameter fiber, and a calculus phantom (Plaster of Paris, 10 × 10 × 10 mm 3 ) was utilized to mimic laser lithotripsy procedure. The phantom was hung on a stainless steel bar and irradiated by the laser at 0.5, 1.0, and 1.5 J energy per pulse at 10 Hz for 1 s (i.e., 5, 10, and 15 W). Movement of the phantom was recorded by a high-speed camera with a frame rate of 10,000 FPS. The video data files are analyzed by MATLAB program by processing each image frame and obtaining position data of the calculus. With a sample size of 10, the maximum displacement was 1.25 ± 0.10, 3.01 ± 0.52, and 4.37 ± 0.58 mm for 0.5, 1, and 1.5 J energy per pulse, respectively. Using the same laser power, the conventional method showed <0.5 mm total displacement. When reducing the phantom size to 5 × 5 × 5 mm 3 (one eighth in volume), the displacement was very inconsistent. The results suggested that using the pendulum model to eliminate the friction improved sensitivity and repeatability of the experiment. A detailed investigation on calculus movement and other causes of experimental variation will be conducted as a future study.

Advanced Q-switched DPSS lasers for ID-card marking

NASA Astrophysics Data System (ADS)

Hertwig, Michael; Paster, Martin; Terbrueggen, Ralf

2008-02-01

Increased homeland security concerns across the world have generated a strong demand for forgery-proof ID documents. Manufacturers currently employ a variety of high technology techniques to produce documents that are difficult to copy. However, production costs and lead times are still a concern when considering any possible manufacturing technology. Laser marking has already emerged as an important tool in the manufacturer's arsenal, and is currently being utilized to produce a variety of documents, such as plastic ID cards, drivers' licenses, health insurance cards and passports. The marks utilized can range from simple barcodes and text to high resolution, true grayscale images. The technical challenges posed by these marking tasks include delivering adequate mark legibility, minimizing substrate burning or charring, accurately reproducing grayscale data, and supporting the required process throughput. This article covers the advantages and basic requirements on laser marking of cards and reviews how laser output parameters affect marking quality, speed and overall process economics.

Subscale testing of prompt agent defeat formulations

NASA Astrophysics Data System (ADS)

Knott, A.; Stamatis, D.; Svingala, F.; Lightstone, J.; Miller, K.; Bensman, M.; Bohmke, M.

2017-01-01

There is a need to improve the current bioagent defeat systems with formulations that produce lower peak pressure and impulse, sustained high temperatures, and release of biocidal species for prompt defeat applications. In this work, explosive charge configurations similar to fuel-air explosives were detonated in a semi-enclosed chamber configuration. Binder type and fuel-to-oxidizer ratios were varied to observe the effects on combustion performance. Thermocouple measurements and high-speed video were used to monitor the combustion of the dispersed formulation. The down-selected formulations were then tested in a sub-scale vented agent defeat system developed to evaluate performance of formulations against aerosolized Bacillus thuringiensis (Bt) spores. Diagnostics including thermocouples and piezoelectric pressure gauges were utilized to characterize the detonation event. Biological sampling with surface coupons, liquid impingement, and filters of the post detonation environment were utilized to determine spore survivability and to rank the relative effectiveness of each formulation.

Security Risks of Cloud Computing and Its Emergence as 5th Utility Service

NASA Astrophysics Data System (ADS)

Ahmad, Mushtaq

Cloud Computing is being projected by the major cloud services provider IT companies such as IBM, Google, Yahoo, Amazon and others as fifth utility where clients will have access for processing those applications and or software projects which need very high processing speed for compute intensive and huge data capacity for scientific, engineering research problems and also e- business and data content network applications. These services for different types of clients are provided under DASM-Direct Access Service Management based on virtualization of hardware, software and very high bandwidth Internet (Web 2.0) communication. The paper reviews these developments for Cloud Computing and Hardware/Software configuration of the cloud paradigm. The paper also examines the vital aspects of security risks projected by IT Industry experts, cloud clients. The paper also highlights the cloud provider's response to cloud security risks.

Navier-Stokes Simulation of UH-60A Rotor/Wake Interaction Using Adaptive Mesh Refinement

NASA Technical Reports Server (NTRS)

Chaderjian, Neal M.

2017-01-01

Time-dependent Navier-Stokes simulations have been carried out for a flexible UH-60A rotor in forward flight, where the rotor wake interacts with the rotor blades. These flow conditions involved blade vortex interaction and dynamic stall, two common conditions that occur as modern helicopter designs strive to achieve greater flight speeds and payload capacity. These numerical simulations utilized high-order spatial accuracy and delayed detached eddy simulation. Emphasis was placed on understanding how improved rotor wake resolution affects the prediction of the normal force, pitching moment, and chord force of the rotor. Adaptive mesh refinement was used to highly resolve the turbulent rotor wake in a computationally efficient manner. Moreover, blade vortex interaction was found to trigger dynamic stall. Time-dependent flow visualization was utilized to provide an improved understanding of the numerical and physical mechanisms involved with three-dimensional dynamic stall.

Families of FPGA-Based Accelerators for Approximate String Matching1

PubMed Central

Van Court, Tom; Herbordt, Martin C.

2011-01-01

Dynamic programming for approximate string matching is a large family of different algorithms, which vary significantly in purpose, complexity, and hardware utilization. Many implementations have reported impressive speed-ups, but have typically been point solutions – highly specialized and addressing only one or a few of the many possible options. The problem to be solved is creating a hardware description that implements a broad range of behavioral options without losing efficiency due to feature bloat. We report a set of three component types that address different parts of the approximate string matching problem. This allows each application to choose the feature set required, then make maximum use of the FPGA fabric according to that application’s specific resource requirements. Multiple, interchangeable implementations are available for each component type. We show that these methods allow the efficient generation of a large, if not complete, family of accelerators for this application. This flexibility was obtained while retaining high performance: We have evaluated a sample against serial reference codes and found speed-ups of from 150× to 400× over a high-end PC. PMID:21603598

Polarization Imaging Apparatus

NASA Technical Reports Server (NTRS)

Zou, Yingyin K.; Chen, Qiushui

2010-01-01

A polarization imaging apparatus has shown promise as a prototype of instruments for medical imaging with contrast greater than that achievable by use of non-polarized light. The underlying principles of design and operation are derived from observations that light interacts with tissue ultrastructures that affect reflectance, scattering, absorption, and polarization of light. The apparatus utilizes high-speed electro-optical components for generating light properties and acquiring polarization images through aligned polarizers. These components include phase retarders made of OptoCeramic (registered TradeMark) material - a ceramic that has a high electro-optical coefficient. The apparatus includes a computer running a program that implements a novel algorithm for controlling the phase retarders, capturing image data, and computing the Stokes polarization images. Potential applications include imaging of superficial cancers and other skin lesions, early detection of diseased cells, and microscopic analysis of tissues. The high imaging speed of this apparatus could be beneficial for observing live cells or tissues, and could enable rapid identification of moving targets in astronomy and national defense. The apparatus could also be used as an analysis tool in material research and industrial processing.

High speed, intermediate resolution, large area laser beam induced current imaging and laser scribing system for photovoltaic devices and modules

NASA Astrophysics Data System (ADS)

Phillips, Adam B.; Song, Zhaoning; DeWitt, Jonathan L.; Stone, Jon M.; Krantz, Patrick W.; Royston, John M.; Zeller, Ryan M.; Mapes, Meghan R.; Roland, Paul J.; Dorogi, Mark D.; Zafar, Syed; Faykosh, Gary T.; Ellingson, Randy J.; Heben, Michael J.

2016-09-01

We have developed a laser beam induced current imaging tool for photovoltaic devices and modules that utilizes diode pumped Q-switched lasers. Power densities on the order of one sun (100 mW/cm2) can be produced in a ˜40 μm spot size by operating the lasers at low diode current and high repetition rate. Using galvanostatically controlled mirrors in an overhead configuration and high speed data acquisition, large areas can be scanned in short times. As the beam is rastered, focus is maintained on a flat plane with an electronically controlled lens that is positioned in a coordinated fashion with the movements of the mirrors. The system can also be used in a scribing mode by increasing the diode current and decreasing the repetition rate. In either mode, the instrument can accommodate samples ranging in size from laboratory scale (few cm2) to full modules (1 m2). Customized LabVIEW programs were developed to control the components and acquire, display, and manipulate the data in imaging mode.

Receiver-Assisted Congestion Control to Achieve High Throughput in Lossy Wireless Networks

NASA Astrophysics Data System (ADS)

Shi, Kai; Shu, Yantai; Yang, Oliver; Luo, Jiarong

2010-04-01

Many applications would require fast data transfer in high-speed wireless networks nowadays. However, due to its conservative congestion control algorithm, Transmission Control Protocol (TCP) cannot effectively utilize the network capacity in lossy wireless networks. In this paper, we propose a receiver-assisted congestion control mechanism (RACC) in which the sender performs loss-based control, while the receiver is performing delay-based control. The receiver measures the network bandwidth based on the packet interarrival interval and uses it to compute a congestion window size deemed appropriate for the sender. After receiving the advertised value feedback from the receiver, the sender then uses the additive increase and multiplicative decrease (AIMD) mechanism to compute the correct congestion window size to be used. By integrating the loss-based and the delay-based congestion controls, our mechanism can mitigate the effect of wireless losses, alleviate the timeout effect, and therefore make better use of network bandwidth. Simulation and experiment results in various scenarios show that our mechanism can outperform conventional TCP in high-speed and lossy wireless environments.

A study of sea lion hydrodynamics using a robotic foreflipper platform

NASA Astrophysics Data System (ADS)

Kulkarni, Aditya A.; Patel, Rahi K.; Leftwich, Megan C.

2016-11-01

Unlike most fish and mammals-that utilize BCF swimming-sea lions rely on their foreflippers to generate thrust without a characteristic flapping frequency. This unique swimming style allows the sea lion to be highly maneuverable, while also producing high amounts of thrust. To explore this motion, and the physics that underlies it, we use novel markerless tracking techniques on untrained sea lions at the Smithsonian National Zoo in Washington, D.C to get the complete motion during different maneuvers. High speed video and three-dimensional surface reconstruction techniques are used to extract the foreflippers kinematics during the thrust phase. Using this data, pitch angle is calculated with respect to the base of the flipper to build a scaled robotic flipper. Dye visualization is carried out in a water channel by injecting dye upstream of the leading edge of the flipper with flow speed set to explore different parameters, like Reynolds number or angular velocity. Results show low pressure on the upper surface of the flipper causes the fluid to be pulled around the flipper forming a vortex that moves fully out of the plane.

Frequency Response Studies using Receptance Coupling Approach in High Speed Spindles

NASA Astrophysics Data System (ADS)

Shaik, Jakeer Hussain; Ramakotaiah, K.; Srinivas, J.

2018-01-01

In order to assess the stability of high speed machining, estimate the frequency response at the end of tool tip is of great importance. Evaluating dynamic response of several combinations of integrated spindle-tool holder-tool will consume a lot of time. This paper presents coupled field dynamic response at tool tip for the entire integrated spindle tool unit. The spindle unit is assumed to be relying over the front and rear bearings and investigated using the Timoshenko beam theory to arrive the receptances at different locations of the spindle-tool unit. The responses are further validated with conventional finite element model as well as with the experiments. This approach permits quick outputs without losing accuracy of solution and further these methods are utilized to analyze the various design variables on system dynamics. The results obtained through this analysis are needed to design the better spindle unit in an attempt to reduce the frequency amplitudes at the tool tip to improvise the milling stability during cutting process.

Evaluation and analysis on the coupling performance of a high-speed turboexpander compressor

NASA Astrophysics Data System (ADS)

Chen, Shuangtao; Fan, Yufeng; Yang, Shanju; Chen, Xingya; Hou, Yu

2017-12-01

A high-speed turboexpander compressor (TEC) for small reverse Brayton air refrigerator is tested and analyzed in the present work. A TEC consists of an expander and a compressor, which are coupled together and interact with each other directly. Meanwhile, the expander and compressor have different effects on the refrigerator. The TEC overall efficiency, which contains effects of the expander's expansion, the compressor's pre-compression, and the pressure drop between them, was proved. It unifies influences of both compression and expansion processes on the COP of refrigerator and could be used to evaluate the TEC overall performance. Then, the coupling parameters were analyzed, which shows that for a TEC, the expander efficiency should be fully utilized first, followed by the compressor pressure ratio. Experiments were carried out to test the TEC coupling performances. The results indicated that, the TEC overall efficiency could reach 67.2%, and meanwhile 22.3% of the energy output was recycled.

Loss of gas from echogenic liposomes exposed to pulsed ultrasound

PubMed Central

Raymond, Jason L.; Luan, Ying; Peng, Tao; Huang, Shao-Ling; McPherson, David D.; Versluis, Michel; de Jong, Nico; Holland, Christy K.

2017-01-01

The destruction of echogenic liposomes (ELIP) in response to pulsed ultrasound excitations has been studied acoustically previously. However, the mechanism underlying the loss of echogenicity due to cavitation of ELIP has not been fully clarified. In this study, an ultra-high speed imaging approach was employed to observe the destruction phenomena of single ELIP exposed to ultrasound bursts at a center frequency of 6- MHz. We observed a rapid size reduction during the ultrasound excitation in 139 out of 397 (35 %) ultra-high-speed recordings. The shell dilation rate, which is defined as the microbubble wall velocity divided by the instantaneous radius, Ṙ/R, was extracted from the radius versus time response of each ELIP, and was found to be correlated with the deflation. Fragmentation and surface mode vibrations were also observed and are shown to depend on the applied acoustic pressure and initial radius. Results from this study can be utilized to optimize the theranostic application of ELIP, e.g., by tuning the size distribution or the excitation frequency. PMID:27811382

High-speed engine/component performance assessment using exergy and thrust-based methods

NASA Technical Reports Server (NTRS)

Riggins, D. W.

1996-01-01

This investigation summarizes a comparative study of two high-speed engine performance assessment techniques based on energy (available work) and thrust-potential (thrust availability). Simple flow-fields utilizing Rayleigh heat addition and one-dimensional flow with friction are used to demonstrate the fundamental inability of conventional energy techniques to predict engine component performance, aid in component design, or accurately assess flow losses. The use of the thrust-based method on these same examples demonstrates its ability to yield useful information in all these categories. Energy and thrust are related and discussed from the stand-point of their fundamental thermodynamic and fluid dynamic definitions in order to explain the differences in information obtained using the two methods. The conventional definition of energy is shown to include work which is inherently unavailable to an aerospace Brayton engine. An engine-based energy is then developed which accurately accounts for this inherently unavailable work; performance parameters based on this quantity are then shown to yield design and loss information equivalent to the thrust-based method.

Bacterial growth laws reflect the evolutionary importance of energy efficiency.

PubMed

Maitra, Arijit; Dill, Ken A

2015-01-13

We are interested in the balance of energy and protein synthesis in bacterial growth. How has evolution optimized this balance? We describe an analytical model that leverages extensive literature data on growth laws to infer the underlying fitness landscape and to draw inferences about what evolution has optimized in Escherichia coli. Is E. coli optimized for growth speed, energy efficiency, or some other property? Experimental data show that at its replication speed limit, E. coli produces about four mass equivalents of nonribosomal proteins for every mass equivalent of ribosomes. This ratio can be explained if the cell's fitness function is the the energy efficiency of cells under fast growth conditions, indicating a tradeoff between the high energy costs of ribosomes under fast growth and the high energy costs of turning over nonribosomal proteins under slow growth. This model gives insight into some of the complex nonlinear relationships between energy utilization and ribosomal and nonribosomal production as a function of cell growth conditions.

High-Speed Photographic Study of Wave Propagation and Impact Damage in Fused Silica and AlON Using the Edge-On Impact (EOI) Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strassburger, E.; Patel, P.; McCauley, J. W.

An Edge-on Impact (EOI) technique, developed at the Ernst-Mach-Institute (EMI), coupled with a Cranz-Schardin high-speed camera, has been successfully utilized to visualize dynamic fracture in many brittle materials. In a typical test, the projectile strikes one edge of a specimen and damage formation and fracture propagation is recorded during the first 20 {mu}s after impact. In the present study, stress waves and damage propagation in fused silica and AlON were examined by means of two modified Edge-on Impact arrangements. In one arrangement, fracture propagation was observed simultaneously in side and top views of the specimens by means of two Cranz-Schardinmore » cameras. In another arrangement, the photographic technique was modified by placing the specimen between crossed polarizers and using the photo-elastic effect to visualize the stress waves. Pairs of impact tests at approximately equivalent velocities were carried out in transmitted plane (shadowgraphs) and crossed polarized light.« less

A rapid excitation-emission matrix fluorometer utilizing supercontinuum white light and acousto-optic tunable filters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wenbo; Department of Dermatology and Skin Science, University of British Columbia, 835 West 10th Avenue, Vancouver, British Columbia V5Z 4E8; Department of Biomedical Engineering, University of British Columbia, KAIS 5500, 2332 Main Mall, Vancouver, British Columbia V6T 1Z4

Scanning speed and coupling efficiency of excitation light to optic fibres are two major technical challenges that limit the potential of fluorescence excitation-emission matrix (EEM) spectrometer for on-line applications and in vivo studies. In this paper, a novel EEM system, utilizing a supercontinuum white light source and acousto-optic tunable filters (AOTFs), was introduced and evaluated. The supercontinuum white light, generated by pumping a nonlinear photonic crystal fiber with an 800 nm femtosecond laser, was efficiently coupled into a bifurcated optic fiber bundle. High speed EEM spectral scanning was achieved using AOTFs both for selecting excitation wavelength and scanning emission spectra.more » Using calibration lamps (neon and mercury argon), wavelength deviations were determined to vary from 0.18 nm to −0.70 nm within the spectral range of 500–850 nm. Spectral bandwidth for filtered excitation light broadened by twofold compared to that measured with monochromatic light between 650 nm and 750 nm. The EEM spectra for methanol solutions of laser dyes were successfully acquired with this rapid fluorometer using an integration time of 5 s.« less

Ship-borne measurements of aerosol optical depth over remote oceans and its dependence on wind speed

NASA Astrophysics Data System (ADS)

Smirnov, A.; Sayer, A. M.; Holben, B. N.; Hsu, N. C.; Sakerin, S. M.; Macke, A.; Nelson, N. B.; Courcoux, Y.; Smyth, T. J.; Croot, P. L.; Quinn, P.; Sciare, J.; Gulev, S. K.; Piketh, S.; Losno, R.; Kinne, S. A.; Radionov, V. F.

2011-12-01

Aerosol production sources over the World Ocean and various factors determining aerosol spatial and temporal distribution are important for understanding the Earth's radiation budget and aerosol-cloud interactions. Sea-salt aerosol production, being a major source of aerosol over remote oceans, depends on surface wind speed. Recently in a number of publications the effect of wind speed on aerosol optical depth (AOD) has been presented utilizing coastal, island-based and satellite-based AOD measurements. However, the influence of wind speed on the columnar optical depth is still poorly understood, because not all factors and precursors influencing AOD dependence can be accounted for. The Maritime Aerosol Network (a component of AERONET) data archive provides an excellent opportunity to analyze in depth a relationship between ship-based AOD measurements and wind speed. We considered only data presumably not influenced by urban/industrial continental sources, dust outbreaks, biomass burning, or glaciers and pack ice. Additional restrictions imposed on the data set were acceptance of only points taken not closer than two degrees from the nearest landmass. We present analyses on the effect of surface (deck-level) wind speed (acquired onboard, modeled by NCEP, measured from satellite) on AOD and its spectral dependence. Latitudinal comparison of measured onboard and modeled wind speeds showed relatively small bias, which was higher at high latitudes. Instantaneous AOD measurements and daily means yielded similar relationships with various wind speed subsets (instantaneous ship-based and NCEP, averaged over previous 24 hours, steady, satellite retrieved). We compared regression statistics of optical parameters versus wind speed presented in various papers and based on various satellite and sunphotometer measurements. Overall, despite certain scatter, the current work and a majority of publications showed consistent patterns, with the AOD versus wind speed (range 2-16 m/s) dependence close to linear.

Photo-Machining of Semiconductor Related Materials with Femtosecond Laser Ablation and Characterization of Its Properties

NASA Astrophysics Data System (ADS)

Yokotani, Atushi; Mizuno, Toshio; Mukumoto, Toru; Kawahara, Kousuke; Ninomiya, Takahumi; Sawada, Hiroshi; Kurosawa, Kou

We have analyzed the drilling process with femtosecond laser on the silicon surface in order to investigate a degree of thermal effect during the dicing process of the very thin silicon substrate. A regenerative amplified Ti:Al2O3 laser (E= 30˜500 μJ/pulse, τ= 200 fs, λ= 780 nm, f= 10 Hz) was used and focused onto a 50 μm-thick silicon sample. ICCD (Intensified Charge coupled Device) camera with a high-speed gate of 5 ns was utilized to take images of processing hole. First, we investigated the dependence of laser energy on the speed of the formation of the drilled hole. As a result, it was found that the lager the energy, the slower the speed of the formation under the minimum hole was obtained. Consequently, in the case of defocused condition, even when the smaller the energy density was used, the very slow speed of formation and the much lager thermal effects are simultaneously observed. So we can say that the degree of the thermal effects is not simply related to energy density of the laser but strongly related to the speed of the formation, which can be measured by the ICCD camera. The similar tendency was also obtained for other materials, which are important for the fabrication of ICs (Al, Cu, SiO2 and acrylic resin).

Driver injury severity related to inclement weather at highway-rail grade crossings in the United States.

PubMed

Hao, Wei; Daniel, Janice

2016-01-01

Previous studies on crash modeling at highway-rail grade crossings were aimed at exploring the factors that are likely to increase the crash frequencies at highway-rail grade crossings. In recent years, modeling driver's injury severity at highway-rail grade crossings has received interest. Because there were substantial differences among different weather conditions for driver's injury severity, this study attempts to explore the impact of weather influence on driver injury at highway-rail grade crossing. Utilizing the most recent 10 years (2002-2011) of highway-rail grade crossing accident data, this study applied a mixed logit model to explore the determinants of driver injury severity under different weather conditions at highway-rail grade crossing. Analysis results indicate that drivers' injury severity at highway-rail grade crossings is strongly different for different weather conditions. It was found that the factors significantly impacting driver injury severity at highway-rail grade crossings include motor vehicle speed, train speed, driver's age, gender, area type, lighting condition, highway pavement, traffic volume, and time of day. The findings of this study indicate that crashes are more prevalent if vehicle drivers are driving at high speed or the oncoming trains are high speed. Hence, a reduction in speed limit during inclement weather conditions could be particularly effective in moderating injury severity, allowing more reaction time for last-minute maneuvering and braking in moments before impacts. In addition, inclement weather-related crashes were more likely to occur in open areas and highway-rail grade crossings without pavement and lighting. Paved highway-rail grade crossings with installation of lights could be particularly effective in moderating injury severity.

Disposable pen-shaped capillary gel electrophoresis cartridge for fluorescence detection of bio-molecules

NASA Astrophysics Data System (ADS)

Amirkhanian, Varoujan; Tsai, Shou-Kuan

2014-03-01

We introduce a novel and cost-effective capillary gel electrophoresis (CGE) system utilizing disposable pen-shaped gelcartridges for highly efficient, high speed, high throughput fluorescence detection of bio-molecules. The CGE system has been integrated with dual excitation and emission optical-fibers with micro-ball end design for fluorescence detection of bio-molecules separated and detected in a disposable pen-shaped capillary gel electrophoresis cartridge. The high-performance capillary gel electrophoresis (CGE) analyzer has been optimized for glycoprotein analysis type applications. Using commercially available labeling agent such as ANTS (8-aminonapthalene-1,3,6- trisulfonate) as an indicator, the capillary gel electrophoresis-based glycan analyzer provides high detection sensitivity and high resolving power in 2-5 minutes of separations. The system can hold total of 96 samples, which can be automatically analyzed within 4-5 hours. This affordable fiber optic based fluorescence detection system provides fast run times (4 minutes vs. 20 minutes with other CE systems), provides improved peak resolution, good linear dynamic range and reproducible migration times, that can be used in laboratories for high speed glycan (N-glycan) profiling applications. The CGE-based glycan analyzer will significantly increase the pace at which glycoprotein research is performed in the labs, saving hours of preparation time and assuring accurate, consistent and economical results.

Application Characterization at Scale: Lessons learned from developing a distributed Open Community Runtime system for High Performance Computing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landwehr, Joshua B.; Suetterlein, Joshua D.; Marquez, Andres

2016-05-16

Since 2012, the U.S. Department of Energy’s X-Stack program has been developing solutions including runtime systems, programming models, languages, compilers, and tools for the Exascale system software to address crucial performance and power requirements. Fine grain programming models and runtime systems show a great potential to efficiently utilize the underlying hardware. Thus, they are essential to many X-Stack efforts. An abundant amount of small tasks can better utilize the vast parallelism available on current and future machines. Moreover, finer tasks can recover faster and adapt better, due to a decrease in state and control. Nevertheless, current applications have been writtenmore » to exploit old paradigms (such as Communicating Sequential Processor and Bulk Synchronous Parallel processing). To fully utilize the advantages of these new systems, applications need to be adapted to these new paradigms. As part of the applications’ porting process, in-depth characterization studies, focused on both application characteristics and runtime features, need to take place to fully understand the application performance bottlenecks and how to resolve them. This paper presents a characterization study for a novel high performance runtime system, called the Open Community Runtime, using key HPC kernels as its vehicle. This study has the following contributions: one of the first high performance, fine grain, distributed memory runtime system implementing the OCR standard (version 0.99a); and a characterization study of key HPC kernels in terms of runtime primitives running on both intra and inter node environments. Running on a general purpose cluster, we have found up to 1635x relative speed-up for a parallel tiled Cholesky Kernels on 128 nodes with 16 cores each and a 1864x relative speed-up for a parallel tiled Smith-Waterman kernel on 128 nodes with 30 cores.« less

The Effects of Wind and Surfactants on Mechanically Generated Spilling Breakers

NASA Astrophysics Data System (ADS)

Liu, X.; Diorio, J. D.; Duncan, J. H.

2007-11-01

The effects of both wind and surfactants on mechanically generated weakly spilling breakers are explored in a wind wave tank that is 11.8 m long, 1.15 m wide and 1.8 m high (1.0 m of water). A wave maker, which resides at the upwind end of the tank, is used to generate the breakers via a dispersive focusing method with a central wave packet frequency of 1.15 Hz. Low wind speeds (less than 3.0 m/s) are used to minimize the effect of short-wavelength wind-generated waves on the breakers. The profiles of the spilling breakers along the center plane of the tank are measured with an LIF technique that utilizes a high-speed digital movie camera. Measurements are performed with clean water and water mixed with various concentrations of Triton X-100, a soluble surfactant. It is found that the capillary waves/bulge patterns found in the initial stages of spilling breakers are dramatically affected by wind and surfactants. The size of bulge increases with the wind speed while the capillary waves are kept nearly the same. In the presence of surfactants and wind, both the amplitude and number of capillary waves are reduced and the slope of the front face of the wave increases.

Sabot high speed interceptor AE 4273 aircraft design

NASA Technical Reports Server (NTRS)

Dober, Dave; Al-Hashel, Waleed; Baldocchi, Bob; Berg, Tim; Lindsay, Curt; Mcatee, Aaron; Sergent, Dan; Dunbrack, Harry

1992-01-01

Today's carrier based deck launched intercept (DLI) mission is a vital one that is aimed at protecting the carrier battle group and detering potential adversaries. The assets deployed on our carrier decks are able to complete this mission but with very limited range. The waverider concept has great potential to increase the range of this carrier based mission. As a result, a request for proposals (RFP) was developed which contains design requirements for an aircraft that can complete this mission through the utilization of waverider technology.

Fiber-Optic/Photoelastic Flow Sensors

NASA Technical Reports Server (NTRS)

Wesson, Laurence N.; Cabato, Nellie L.; Brooks, Edward F.

1995-01-01

Simple, rugged, lightweight transducers detect periodic vortices. Fiber-optic-coupled transducers developed to measure flows over wide dynamic ranges and over wide temperature ranges in severe environments. Used to measure flows of fuel in advanced aircraft engines. Feasibility of sensors demonstrated in tests of prototype sensor in water flowing at various temperatures and speeds. Particularly attractive for aircraft applications because optical fibers compact and make possible transmission of sensor signals at high rates with immunity from electromagnetic interference at suboptical frequencies. Sensors utilize optical-to-optical conversion via photoelastic effect.

Obstacle evasion in free-space optical communications utilizing Airy beams.

PubMed

Zhu, Guoxuan; Wen, Yuanhui; Wu, Xiong; Chen, Yujie; Liu, Jie; Yu, Siyuan

2018-03-15

A high speed free-space optical communication system capable of self-bending signal transmission around line-of-sight obstacles is proposed and demonstrated. Airy beams are generated and controlled to achieve different propagating trajectories, and the signal transmission characteristics of these beams around the obstacle are investigated. Our results confirm that, by optimizing their ballistic trajectories, Airy beams are able to bypass obstacles with more signal energy and thus improve the communication performance compared with normal Gaussian beams.

Obstacle evasion in free-space optical communications utilizing Airy beams

NASA Astrophysics Data System (ADS)

Zhu, Guoxuan; Wen, Yuanhui; Wu, Xiong; Chen, Yujie; Liu, Jie; Yu, Siyuan

2018-03-01

A high speed free-space optical communication system capable of self-bending signal transmission around line-of-sight obstacles is proposed and demonstrated. Airy beams are generated and controlled to achieve different propagating trajectories, and the signal transmission characteristics of these beams around the obstacle are investigated. Our results confirm that, by optimising their ballistic trajectories, Airy beams are able to bypass obstacles with more signal energy and thus improve the communication performance compared with normal Gaussian beams.

Conference on Aerospace Transparent Materials and Enclosures Held at Scottsdale, Arizona on 11-14 July 1983

DTIC Science & Technology

1983-12-01

UTILIZING MTAL & COMPOSITE MATERIALS FOR AFT ARCH REINYORCEMENT This paper provides a review of the T-38 arch reinforcement as it relates to the T-38... review of high speed motion pictures showed that the PVB inboard of the parting medium was now pulling chips out of the core during the impact event...tensile loads less than the yield L stress, and has been thoroughly reviewed by Kambour [8], and by Rabinowitz and Beardmore [9]. The minimum load

Dimensional Precision Research of Wax Molding Rapid Prototyping based on Droplet Injection

NASA Astrophysics Data System (ADS)

Mingji, Huang; Geng, Wu; yan, Shan

2017-11-01

The traditional casting process is complex, the mold is essential products, mold quality directly affect the quality of the product. With the method of rapid prototyping 3D printing to produce mold prototype. The utility wax model has the advantages of high speed, low cost and complex structure. Using the orthogonal experiment as the main method, analysis each factors of size precision. The purpose is to obtain the optimal process parameters, to improve the dimensional accuracy of production based on droplet injection molding.

Optically-programmable nonlinear photonic component for dielectric-loaded plasmonic circuitry.

PubMed

Krasavin, Alexey V; Randhawa, Sukanya; Bouillard, Jean-Sebastien; Renger, Jan; Quidant, Romain; Zayats, Anatoly V

2011-12-05

We demonstrate both experimentally and numerically a compact and efficient, optically tuneable plasmonic component utilizing a surface plasmon polariton ring resonator with nonlinearity based on trans-cis isomerization in a polymer material. We observe more than 3-fold change between high and low transmission states of the device at milliwatt control powers (∼100 W/cm² by intensity), with the performance limited by switching speed of the material. Such plasmonic components can be employed in optically programmable and reconfigurable integrated photonic circuitry.

Optical RISC computer

NASA Astrophysics Data System (ADS)

Guilfoyle, Peter S.; Stone, Richard V.; Hessenbruch, John M.; Zeise, Frederick F.

1993-07-01

A second generation digital optical computer (DOC II) has been developed which utilizes a RISC based operating system as its host. This 32 bit, high performance (12.8 GByte/sec), computing platform demonstrates a number of basic principals that are inherent to parallel free space optical interconnects such as speed (up to 1012 bit operations per second) and low power 1.2 fJ per bit). Although DOC II is a general purpose machine, special purpose applications have been developed and are currently being evaluated on the optical platform.

Establishment of an Off-Highway Vehicle (OHV) Program at Arnold Air Force Base, Tennessee Final Environmental Assessment

DTIC Science & Technology

2010-05-01

adverse impacts. This process was applied to the entire OHV area for the following resource areas: geomorphology and soils , water quality and...interaction with highly erodible soils . If such areas are utilized, operational constraints would be implemented that would minimize impacts in these areas...such as restricted use in wet soils and speed limits. At the motocross 2 area, the riding h·ack would be developed based on constraints associated

Investigation of the Jet Noise Prediction Theory and Application Utilizing the PAO Formulation. [mathematical model for calculating noise radiation

NASA Technical Reports Server (NTRS)

1973-01-01

Application of the Phillips theory to engineering calculations of rocket and high speed jet noise radiation is reported. Presented are a detailed derivation of the theory, the composition of the numerical scheme, and discussions of the practical problems arising in the application of the present noise prediction method. The present method still contains some empirical elements, yet it provides a unified approach in the prediction of sound power, spectrum, and directivity.

High-speed microwave-promoted hetero-Diels-Alder reactions of 2(1H)-pyrazinones in ionic liquid doped solvents.

PubMed

Van Der Eycken, Erik; Appukkuttan, Prasad; De Borggraeve, Wim; Dehaen, Wim; Dallinger, Doris; Kappe, C Oliver

2002-11-01

Inter- and intramolecular hetero-Diels-Alder reactions in a series of functionalized 2(1H)-pyrazinones were investigated under controlled microwave irradiation. The cycloaddition reactions were efficiently performed in sealed tubes, utilizing either a combination of 1,2-dichloroethane and a thermally stable ionic liquid, or 1,2-dichlorobenzene as reaction medium. In all cases, a significant rate-enhancement using microwave flash heating as compared to thermal heating was observed.

A decade of aeroacoustic research at NASA Ames Research Center

NASA Technical Reports Server (NTRS)

Schmitz, Frederic H.; Mosher, M.; Kitaplioglu, Cahit; Cross, J.; Chang, I.

1988-01-01

The rotorcraft aeroacoustic research accomplishments of the past decade at Ames Research Center are reviewed. These include an extensive sequence of flight, ground, and wind tunnel tests that have utilized the facilities to guide and pioneer theoretical research. Many of these experiments were of benchmark quality. The experiments were used to isolate the inadequacies of linear theory in high-speed impulsive noise research, have led to the development of theoretical approaches, and have guided the emerging discipline of computational fluid dynamics to rotorcraft aeroacoustic problems.

Dopamine reward prediction-error signalling: a two-component response

PubMed Central

Schultz, Wolfram

2017-01-01

Environmental stimuli and objects, including rewards, are often processed sequentially in the brain. Recent work suggests that the phasic dopamine reward prediction-error response follows a similar sequential pattern. An initial brief, unselective and highly sensitive increase in activity unspecifically detects a wide range of environmental stimuli, then quickly evolves into the main response component, which reflects subjective reward value and utility. This temporal evolution allows the dopamine reward prediction-error signal to optimally combine speed and accuracy. PMID:26865020

Processing Speed Measures as Clinical Markers for Children with Language Impairment

ERIC Educational Resources Information Center

Park, Jisook; Miller, Carol A.; Mainela-Arnold, Elina

2015-01-01

Purpose: This study investigated the relative utility of linguistic and nonlinguistic processing speed tasks as predictors of language impairment (LI) in children across 2 time points. Method: Linguistic and nonlinguistic reaction time data, obtained from 131 children (89 children with typical development [TD] and 42 children with LI; 74 boys and…

Micro-optical system based 3D imaging for full HD depth image capturing

NASA Astrophysics Data System (ADS)

Park, Yong-Hwa; Cho, Yong-Chul; You, Jang-Woo; Park, Chang-Young; Yoon, Heesun; Lee, Sang-Hun; Kwon, Jong-Oh; Lee, Seung-Wan

2012-03-01

20 Mega-Hertz-switching high speed image shutter device for 3D image capturing and its application to system prototype are presented. For 3D image capturing, the system utilizes Time-of-Flight (TOF) principle by means of 20MHz high-speed micro-optical image modulator, so called 'optical shutter'. The high speed image modulation is obtained using the electro-optic operation of the multi-layer stacked structure having diffractive mirrors and optical resonance cavity which maximizes the magnitude of optical modulation. The optical shutter device is specially designed and fabricated realizing low resistance-capacitance cell structures having small RC-time constant. The optical shutter is positioned in front of a standard high resolution CMOS image sensor and modulates the IR image reflected from the object to capture a depth image. Suggested novel optical shutter device enables capturing of a full HD depth image with depth accuracy of mm-scale, which is the largest depth image resolution among the-state-of-the-arts, which have been limited up to VGA. The 3D camera prototype realizes color/depth concurrent sensing optical architecture to capture 14Mp color and full HD depth images, simultaneously. The resulting high definition color/depth image and its capturing device have crucial impact on 3D business eco-system in IT industry especially as 3D image sensing means in the fields of 3D camera, gesture recognition, user interface, and 3D display. This paper presents MEMS-based optical shutter design, fabrication, characterization, 3D camera system prototype and image test results.

Extended dynamic range of Doppler OCT by application of a new method to high density B-scans using a MHz FDML swept laser source (Conference Presentation)

NASA Astrophysics Data System (ADS)

Elahi, Sahar; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

2017-02-01

The limited dynamic range of optical coherence tomography (OCT) Doppler velocity measurements makes it difficult to conduct experiments on samples requiring a large dynamic range without phase wrapping at high velocities or loss of sensitivity at slow velocities. Hemodynamics and wall motion undergo significant increases in velocity as the embryonic heart develops. Experimental studies indicate that altered hemodynamics in early-stage embryonic hearts can lead to congenital heart diseases (CHDs), motivating close monitoring of blood flow over several stages of development. We have built a high-speed OCT system using an FDML laser (Optores GmbH, Germany) at a sweep rate of 1.68 MHz (axial resolution - 12 μm, sensitivity - 105 dB, phase stability - 17 mrad). The speed of this OCT system allows us to acquire high-density B-scans to obtain an extended velocity dynamic range without sacrificing the frame rate (100 Hz). The extended dynamic range within a frame is achieved by varying the A-scan interval at which the phase difference is found, enabling detection of velocities ranging from tens of microns per second to hundreds of millimeters per second. The extra lines in a frame can also be utilized to improve the structural and Doppler images via complex averaging. In structural images where the presence of blood causes additional scattering, complex averaging helps retrieve features located deeper in the tissue. Moreover, high-density frames can be registered to 4D volumes to determine the orthogonal direction of flow for calculating shear stress as well as estimating the cardiac output. In conclusion, high density B-scans acquired by our high-speed OCT system enable image enhancement and direct measurement of biological parameters in cohort studies.

Clinical utility of the Wechsler Adult Intelligence Scale-Fourth Edition after traumatic brain injury.

PubMed

Donders, Jacobus; Strong, Carrie-Ann H

2015-02-01

The performance of 100 patients with traumatic brain injury (TBI) on the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) was compared with that of 100 demographically matched neurologically healthy controls. Processing Speed was the only WAIS-IV factor index that was able to discriminate between persons with moderate-severe TBI on the one hand and persons with either less severe TBI or neurologically healthy controls on the other hand. The Processing Speed index also had acceptable sensitivity and specificity when differentiating between patients with TBI who either did or did not have scores in the clinically significant range on the Trail Making Test. It is concluded that WAIS-IV Processing Speed has acceptable clinical utility in the evaluation of patients with moderate-severe TBI but that it should be supplemented with other measures to assure sufficient accuracy in the diagnostic process. © The Author(s) 2014.

Accuracy of Immunofluorescence in the Diagnosis of Primary Ciliary Dyskinesia

PubMed Central

Frost, Emily; Dixon, Mellisa; Ollosson, Sarah; Kilpin, Kate; Patel, Mitali; Scully, Juliet; Rogers, Andrew V.; Mitchison, Hannah M.; Bush, Andrew; Hogg, Claire

2017-01-01

Rationale: The standard approach to diagnosis of primary ciliary dyskinesia (PCD) in the United Kingdom consists of assessing ciliary function by high-speed microscopy and ultrastructure by election microscopy, but equipment and expertise is not widely available internationally. The identification of biallelic disease-causing mutations is also diagnostic, but many disease-causing genes are unknown, and testing is not widely available outside the United States. Fluorescent antibodies to ciliary proteins are used to validate research genetic studies, but diagnostic utility in this disease has not been systematically evaluated. Objectives: To determine utility of a panel of six fluorescent labeled antibodies as a diagnostic tool for PCD. Methods: The study used immunofluorescent labeling of nasal brushings from a discovery cohort of 35 patients diagnosed with PCD by ciliary ultrastructure, and a diagnostic accuracy cohort of 386 patients referred with symptoms suggestive of disease. The results were compared with diagnostic outcome. Measurements and Main Results: Immunofluorescence correctly identified mislocalized or absent staining in 100% of the discovery cohort. In the diagnostic cohort immunofluorescence successfully identified 22 of 25 patients with PCD and normal staining in all 252 in whom PCD was considered highly unlikely. In addition, immunofluorescence provided a result in 55% (39) of cases that were previously inconclusive. Immunofluorescence results were available within 14 days, costing $187 per sample compared with electron microscopy (27 days; cost $1,452). Conclusions: Immunofluorescence is a highly specific diagnostic test for PCD, and it improves the speed and availability of diagnostic testing. However, sensitivity is limited and immunofluorescence is not suitable as a stand-alone test. PMID:28199173

Acceleration performance of individual European sea bass Dicentrarchus labrax measured with a sprint performance chamber: comparison with high-speed cinematography and correlates with ecological performance.

PubMed

Vandamm, Joshua P; Marras, Stefano; Claireaux, Guy; Handelsman, Corey A; Nelson, Jay A

2012-01-01

Locomotor performance can influence the ecological and evolutionary success of a species. For fish, favorable outcomes of predator-prey encounters are often presumably due to robust acceleration ability. Although escape-response or "fast-start" studies utilizing high-speed cinematography are prevalent, little is known about the contribution of relative acceleration performance to ecological or evolutionary success in a species. This dearth of knowledge may be due to the time-consuming nature of analyzing film, which imposes a practical limit on sample sizes. Herein, we present a high-throughput potential alternative for measuring fish acceleration performance using a sprint performance chamber (SPC). The acceleration performance of a large number of juvenile European sea bass (Dicentrarchus labrax) from two populations was analyzed. Animals from both hatchery and natural ontogenies were assessed, and animals of known acceleration ability had their ecological performance measured in a mesocosm environment. Individuals from one population also had their acceleration performance assessed by both high-speed cinematography and an SPC. Acceleration performance measured in an SPC was lower than that measured by classical high-speed video techniques. However, short-term repeatability and interindividual variation of acceleration performance were similar between the two techniques, and the SPC recorded higher sprint swimming velocities. Wild fish were quicker to accelerate in an SPC and had significantly greater accelerations than all groups of hatchery-raised fish. Acceleration performance had no significant effect on ecological performance (as assessed through animal growth and survival in the mesocosms). However, it is worth noting that wild animals did survive predation in the mesocosm better than farmed ones. Moreover, the hatchery-originated fish that survived the mesocosm experiment, when no predators were present, displayed significantly increased acceleration performance during their 6 mo in the mesocosm; this performance was found to be inversely proportional to growth rate.

Extensibility and limitations of FDDI

NASA Technical Reports Server (NTRS)

Game, David; Maly, Kurt J.

1990-01-01

Recently two standards for Metropolitan Area Networks (MANs), Fiber Distributed Data Interface (FDDI) and Distributed Queue Dual Bus (DQDB), have emerged as the primary competitors for the MAN arena. Great interest exists in building higher speed networks which support large numbers of node and greater distance, and it is not clear what types of protocols are needed for this type of environment. There is some question as to whether or not these MAN standards can be extended to such environments. The extensibility of FDDI to the Gbps range and a long distance environment is investigated. Specification parameters which affect performance are shown and a measure is provided for predicting utilization of FDDI. A comparison of FDDI at 100 Mbps and 1 Gbps is presented. Some specific problems with FDDI are addressed and modifications which improve the viability of FDDI in such high speed networks are investigated.

Advancing the speed, sensitivity and accuracy of biomolecular detection using multi-length-scale engineering

PubMed Central

Kelley, Shana O.; Mirkin, Chad A.; Walt, David R.; Ismagilov, Rustem F.; Toner, Mehmet; Sargent, Edward H.

2015-01-01

Rapid progress in identifying disease biomarkers has increased the importance of creating high-performance detection technologies. Over the last decade, the design of many detection platforms has focused on either the nano or micro length scale. Here, we review recent strategies that combine nano- and microscale materials and devices to produce large improvements in detection sensitivity, speed and accuracy, allowing previously undetectable biomarkers to be identified in clinical samples. Microsensors that incorporate nanoscale features can now rapidly detect disease-related nucleic acids expressed in patient samples. New microdevices that separate large clinical samples into nanocompartments allow precise quantitation of analytes, and microfluidic systems that utilize nanoscale binding events can detect rare cancer cells in the bloodstream more accurately than before. These advances will lead to faster and more reliable clinical diagnostic devices. PMID:25466541

Advancing the speed, sensitivity and accuracy of biomolecular detection using multi-length-scale engineering

NASA Astrophysics Data System (ADS)

Kelley, Shana O.; Mirkin, Chad A.; Walt, David R.; Ismagilov, Rustem F.; Toner, Mehmet; Sargent, Edward H.

2014-12-01

Rapid progress in identifying disease biomarkers has increased the importance of creating high-performance detection technologies. Over the last decade, the design of many detection platforms has focused on either the nano or micro length scale. Here, we review recent strategies that combine nano- and microscale materials and devices to produce large improvements in detection sensitivity, speed and accuracy, allowing previously undetectable biomarkers to be identified in clinical samples. Microsensors that incorporate nanoscale features can now rapidly detect disease-related nucleic acids expressed in patient samples. New microdevices that separate large clinical samples into nanocompartments allow precise quantitation of analytes, and microfluidic systems that utilize nanoscale binding events can detect rare cancer cells in the bloodstream more accurately than before. These advances will lead to faster and more reliable clinical diagnostic devices.

Design of a GaAs/Ge Solar Array for Unmanned Aerial Vehicles

NASA Technical Reports Server (NTRS)

Scheiman, David A.; Brinker, David J.; Bents, David J.; Colozza, Anthony J.

1995-01-01

Unmanned Aerial Vehicles (UAV) are being proposed for many applications including surveillance, mapping and atmospheric studies. These applications require a lightweight, low speed, medium to long duration airplane. Due to the weight, speed, and altitude constraints imposed on such aircraft, solar array generated electric power is a viable alternative to air-breathing engines. Development of such aircraft is currently being funded under the Environmental Research Aircraft and Sensor Technology (ERAST) program. NASA Lewis Research Center (LeRC) is currently building a Solar Electric Airplane to demonstrate UAV technology. This aircraft utilizes high efficiency Applied Solar Energy Corporation (ASEC) GaAs/Ge space solar cells. The cells have been provided by the Air Force through the ManTech Office. Expected completion of the plane is early 1995, with the airplane currently undergoing flight testing using battery power.

Third order LPF type compensator for flexible rotor suspension

NASA Technical Reports Server (NTRS)

Matsushita, Osami; Takahashi, Naohiko; Takagi, Michiyuki

1994-01-01

The tuning job of the compensator for levitating flexible rotors supported by active magnetic bearings (AMB) concerns providing a good damping effect to the critical speed modes while avoiding the spillover problem on the instability of higher bending modes. In this paper, an idea for design of the control law of the compensator based on utilizing a third order low pass filter (LPF) is proposed to essentially enable elimination of the spillover instability. According to the proposed design method, good damping effects for the critical speeds are obtained by the usual phase lead/lag function. Stabilization for all of higher bending modes is completed by the additional function of the 3rd order LPF due to its phase lag approaching about -270 degrees in the high frequency domain. This idea is made clear by experiments and simulations.

Design of a GaAs/Ge solar array for unmanned aerial vehicles

NASA Astrophysics Data System (ADS)

Scheiman, David A.; Brinker, David J.; Bents, David J.; Colozza, Anthony J.

1995-03-01

Unmanned Aerial Vehicles (UAV) are being proposed for many applications including surveillance, mapping and atmospheric studies. These applications require a lightweight, low speed, medium to long duration airplane. Due to the weight, speed, and altitude constraints imposed on such aircraft, solar array generated electric power is a viable alternative to air-breathing engines. Development of such aircraft is currently being funded under the Environmental Research Aircraft and Sensor Technology (ERAST) program. NASA Lewis Research Center (LeRC) is currently building a Solar Electric Airplane to demonstrate UAV technology. This aircraft utilizes high efficiency Applied Solar Energy Corporation (ASEC) GaAs/Ge space solar cells. The cells have been provided by the Air Force through the ManTech Office. Expected completion of the plane is early 1995, with the airplane currently undergoing flight testing using battery power.

Ultrafast time-stretch imaging at 932 nm through a new highly-dispersive fiber

PubMed Central

Wei, Xiaoming; Kong, Cihang; Sy, Samuel; Ko, Ho; Tsia, Kevin K.; Wong, Kenneth K. Y.

2016-01-01

Optical glass fiber has played a key role in the development of modern optical communication and attracted the biotechnology researcher’s great attention because of its properties, such as the wide bandwidth, low attenuation and superior flexibility. For ultrafast optical imaging, particularly, it has been utilized to perform MHz time-stretch imaging with diffraction-limited resolutions, which is also known as serial time-encoded amplified microscopy (STEAM). Unfortunately, time-stretch imaging with dispersive fibers has so far mostly been demonstrated at the optical communication window of 1.5 μm due to lack of efficient dispersive optical fibers operating at the shorter wavelengths, particularly at the bio-favorable window, i.e., <1.0 μm. Through fiber-optic engineering, here we demonstrate a 7.6-MHz dual-color time-stretch optical imaging at bio-favorable wavelengths of 932 nm and 466 nm. The sensitivity at such a high speed is experimentally identified in a slow data-streaming manner. To the best of our knowledge, this is the first time that all-optical time-stretch imaging at ultrahigh speed, high sensitivity and high chirping rate (>1 ns/nm) has been demonstrated at a bio-favorable wavelength window through fiber-optic engineering. PMID:28018737

Ultrafast time-stretch imaging at 932 nm through a new highly-dispersive fiber.

PubMed

Wei, Xiaoming; Kong, Cihang; Sy, Samuel; Ko, Ho; Tsia, Kevin K; Wong, Kenneth K Y

2016-12-01

Optical glass fiber has played a key role in the development of modern optical communication and attracted the biotechnology researcher's great attention because of its properties, such as the wide bandwidth, low attenuation and superior flexibility. For ultrafast optical imaging, particularly, it has been utilized to perform MHz time-stretch imaging with diffraction-limited resolutions, which is also known as serial time-encoded amplified microscopy (STEAM). Unfortunately, time-stretch imaging with dispersive fibers has so far mostly been demonstrated at the optical communication window of 1.5 μm due to lack of efficient dispersive optical fibers operating at the shorter wavelengths, particularly at the bio-favorable window, i.e., <1.0 μm. Through fiber-optic engineering, here we demonstrate a 7.6-MHz dual-color time-stretch optical imaging at bio-favorable wavelengths of 932 nm and 466 nm. The sensitivity at such a high speed is experimentally identified in a slow data-streaming manner. To the best of our knowledge, this is the first time that all-optical time-stretch imaging at ultrahigh speed, high sensitivity and high chirping rate (>1 ns/nm) has been demonstrated at a bio-favorable wavelength window through fiber-optic engineering.

A High-Speed Large-Range Tip-Tilt-Piston Micromirror Array

DOE PAGES

Hopkins, Jonathan B.; Panas, Robert M.; Song, Yuanping; ...

2016-12-01

This work introduces the design of a high fill-factor (>99%) micromirror array (MMA) that consists of 1mm2 hexagonal mirrors, which are expected to each independently achieve continuous, closed-loop control of three degrees of freedom (DOFs)—tip, tilt, and piston—over large ranges (>±10o rotation and >±30μm translation) at high speeds (~45kHz for a 1o amplitude of rotational oscillation). The flexure topology of this array is designed using the Freedom, Actuation, and Constraint Topologies (FACT) synthesis approach, which utilizes geometric shapes to help designers rapidly consider every flexure topology that best achieves a desired set of DOFs driven by decoupled actuators. The geometrymore » of this array’s comb-drive actuators are optimized in conjunction with the geometry of the system’s flexures using a novel approach. The analytical models underlying this approach are verified using finite element analysis (FEA) and validated using experimental data. The capabilities of this new mirror array will enable, or significantly improve, the performance of a variety of high-impact optical technologies such as advanced optical switches, spatial-light modulators, displays, and laser steering or scanning devices.« less

A High-Speed Large-Range Tip-Tilt-Piston Micromirror Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopkins, Jonathan B.; Panas, Robert M.; Song, Yuanping

This work introduces the design of a high fill-factor (>99%) micromirror array (MMA) that consists of 1mm2 hexagonal mirrors, which are expected to each independently achieve continuous, closed-loop control of three degrees of freedom (DOFs)—tip, tilt, and piston—over large ranges (>±10o rotation and >±30μm translation) at high speeds (~45kHz for a 1o amplitude of rotational oscillation). The flexure topology of this array is designed using the Freedom, Actuation, and Constraint Topologies (FACT) synthesis approach, which utilizes geometric shapes to help designers rapidly consider every flexure topology that best achieves a desired set of DOFs driven by decoupled actuators. The geometrymore » of this array’s comb-drive actuators are optimized in conjunction with the geometry of the system’s flexures using a novel approach. The analytical models underlying this approach are verified using finite element analysis (FEA) and validated using experimental data. The capabilities of this new mirror array will enable, or significantly improve, the performance of a variety of high-impact optical technologies such as advanced optical switches, spatial-light modulators, displays, and laser steering or scanning devices.« less

An FPGA-Based High-Speed Error Resilient Data Aggregation and Control for High Energy Physics Experiment

NASA Astrophysics Data System (ADS)

Mandal, Swagata; Saini, Jogender; Zabołotny, Wojciech M.; Sau, Suman; Chakrabarti, Amlan; Chattopadhyay, Subhasis

2017-03-01

Due to the dramatic increase of data volume in modern high energy physics (HEP) experiments, a robust high-speed data acquisition (DAQ) system is very much needed to gather the data generated during different nuclear interactions. As the DAQ works under harsh radiation environment, there is a fair chance of data corruption due to various energetic particles like alpha, beta, or neutron. Hence, a major challenge in the development of DAQ in the HEP experiment is to establish an error resilient communication system between front-end sensors or detectors and back-end data processing computing nodes. Here, we have implemented the DAQ using field-programmable gate array (FPGA) due to some of its inherent advantages over the application-specific integrated circuit. A novel orthogonal concatenated code and cyclic redundancy check (CRC) have been used to mitigate the effects of data corruption in the user data. Scrubbing with a 32-b CRC has been used against error in the configuration memory of FPGA. Data from front-end sensors will reach to the back-end processing nodes through multiple stages that may add an uncertain amount of delay to the different data packets. We have also proposed a novel memory management algorithm that helps to process the data at the back-end computing nodes removing the added path delays. To the best of our knowledge, the proposed FPGA-based DAQ utilizing optical link with channel coding and efficient memory management modules can be considered as first of its kind. Performance estimation of the implemented DAQ system is done based on resource utilization, bit error rate, efficiency, and robustness to radiation.

Comprehensive Modeling and Analysis of Rotorcraft Variable Speed Propulsion System With Coupled Engine/Transmission/Rotor Dynamics

NASA Technical Reports Server (NTRS)

DeSmidt, Hans A.; Smith, Edward C.; Bill, Robert C.; Wang, Kon-Well

2013-01-01

This project develops comprehensive modeling and simulation tools for analysis of variable rotor speed helicopter propulsion system dynamics. The Comprehensive Variable-Speed Rotorcraft Propulsion Modeling (CVSRPM) tool developed in this research is used to investigate coupled rotor/engine/fuel control/gearbox/shaft/clutch/flight control system dynamic interactions for several variable rotor speed mission scenarios. In this investigation, a prototypical two-speed Dual-Clutch Transmission (DCT) is proposed and designed to achieve 50 percent rotor speed variation. The comprehensive modeling tool developed in this study is utilized to analyze the two-speed shift response of both a conventional single rotor helicopter and a tiltrotor drive system. In the tiltrotor system, both a Parallel Shift Control (PSC) strategy and a Sequential Shift Control (SSC) strategy for constant and variable forward speed mission profiles are analyzed. Under the PSC strategy, selecting clutch shift-rate results in a design tradeoff between transient engine surge margins and clutch frictional power dissipation. In the case of SSC, clutch power dissipation is drastically reduced in exchange for the necessity to disengage one engine at a time which requires a multi-DCT drive system topology. In addition to comprehensive simulations, several sections are dedicated to detailed analysis of driveline subsystem components under variable speed operation. In particular an aeroelastic simulation of a stiff in-plane rotor using nonlinear quasi-steady blade element theory was conducted to investigate variable speed rotor dynamics. It was found that 2/rev and 4/rev flap and lag vibrations were significant during resonance crossings with 4/rev lagwise loads being directly transferred into drive-system torque disturbances. To capture the clutch engagement dynamics, a nonlinear stick-slip clutch torque model is developed. Also, a transient gas-turbine engine model based on first principles mean-line compressor and turbine approximations is developed. Finally an analysis of high frequency gear dynamics including the effect of tooth mesh stiffness variation under variable speed operation is conducted including experimental validation. Through exploring the interactions between the various subsystems, this investigation provides important insights into the continuing development of variable-speed rotorcraft propulsion systems.

Modeling Wide-Angle Seismic Data from the Hi-CLIMB Experiment in Tibet

NASA Astrophysics Data System (ADS)

Nowack, R. L.; Griffin, J. D.; Tseng, T.; Chen, W.

2009-12-01

Using data from local and regional events recorded by the Hi-CLIMB array in Tibet, we utilize seismic attributes, including arrival times, Hilbert amplitudes and pulse frequencies, to constrain structures of seismic wave speed and attenuation in the crust and the upper mantle in western China. We construct more than 30 high-quality, regional seismic profiles, and select 14 of these, which show excellent crustal and Pn arrivals, for further analysis. Travel-times from events at regional distances constrain large-scale velocity structures, and four close-in events provide further details on crustal structure. We use the 3-D ray tracer, CRT, to model the travel-times. Initial results indicate that the Moho beneath the Lhasa terrane of southern Tibet is over 73 km deep with a high Pn speed of about 8.2 km/s. In contrast, the Qiangtang terrane farther north shows a thinner crust, by up to 10 km, and a low Pn speed of 7.8-7.9 km/s. Preliminary estimates of upper mantle velocity gradients are between .003 and .004 km/s per km, consistent with previous results by Phillips et al. (2007). We also use P to SV conversions from teleseismic earthquakes to independently constrain variations in speeds of Pn and depths of the Moho. For instance, amplitudes of the SsPmP phase, when its last reflection off the Moho is near-critical, are particularly sensitive to the contrast in seismic wave speeds across the crust-mantle interface; and results from these additional data are consistent with those from modeling of travel-times. Additional seismic attributes, extracted from wave-trains containing Pn and major crustal phases, are being compared with results of numerical modeling based on the spectral element method and asymptotic calculations in laterally varying media, where both lateral and vertical gradients in seismic wave speeds can strongly affect Pn amplitudes and pulse frequencies.

VCSEL-based optical transceiver module for high-speed short-reach interconnect

NASA Astrophysics Data System (ADS)

Yagisawa, Takatoshi; Oku, Hideki; Mori, Tatsuhiro; Tsudome, Rie; Tanaka, Kazuhiro; Daikuhara, Osamu; Komiyama, Takeshi; Ide, Satoshi

2017-02-01

Interconnects have been more important in high-performance computing systems and high-end servers beside its improvements in computing capability. Recently, active optical cables (AOCs) have started being used for this purpose instead of conventionally used copper cables. The AOC enables to extend the transmission distance of the high-speed signals dramatically by its broadband characteristics, however, it tend to increase the cost. In this paper, we report our developed quad small form-factor pluggable (QSFP) AOC utilizing cost-effective optical-module technologies. These are a unique structure using generally used flexible printed circuit (FPC) in combination with an optical waveguide that enables low-cost high-precision assembly with passive alignment, a lens-integrated ferrule that improves productivity by eliminating a polishing process for physical contact of standard PMT connector for the optical waveguide, and an overdrive technology that enables 100 Gb/s (25 Gb/s × 4-channel) operation with low-cost 14 Gb/s vertical-cavity surfaceemitting laser (VCSEL) array. The QSFP AOC demonstrated clear eye opening and error-free operation at 100 Gb/s with high yield rate even though the 14 Gb/s VCSEL was used thanks to the low-coupling loss resulting from the highprecision alignment of optical devices and the over-drive technology.

A Systems Approach to Stress, Stressors and Resilience in Humans

PubMed Central

Oken, Barry S.; Chamine, Irina; Wakeland, Wayne

2014-01-01

The paper focuses on the biology of stress and resilience and their biomarkers in humans from the system science perspective. A stressor pushes the physiological system away from its baseline state towards a lower utility state. The physiological system may return towards the original state in one attractor basin but may be shifted to a state in another, lower utility attractor basin. While some physiological changes induced by stressors may benefit health, there is often a chronic wear and tear cost due to implementing changes to enable the return of the system to its baseline state and maintain itself in the high utility baseline attractor basin following repeated perturbations. This cost, also called allostatic load, is the utility reduction associated with both a change in state and with alterations in the attractor basin that affect system responses following future perturbations. This added cost can increase the time course of the return to baseline or the likelihood of moving into a different attractor basin following a perturbation. Opposite to this is the system’s resilience which influences its ability to return to the high utility attractor basin following a perturbation by increasing the likelihood and/or speed of returning to the baseline state following a stressor. This review paper is a qualitative systematic review; it covers areas most relevant for moving the stress and resilience field forward from a more quantitative and neuroscientific perspective. PMID:25549855

A Novel Speed Compensation Method for ISAR Imaging with Low SNR

PubMed Central

Liu, Yongxiang; Zhang, Shuanghui; Zhu, Dekang; Li, Xiang

2015-01-01

In this paper, two novel speed compensation algorithms for ISAR imaging under a low signal-to-noise ratio (SNR) condition have been proposed, which are based on the cubic phase function (CPF) and the integrated cubic phase function (ICPF), respectively. These two algorithms can estimate the speed of the target from the wideband radar echo directly, which breaks the limitation of speed measuring in a radar system. With the utilization of non-coherent accumulation, the ICPF-based speed compensation algorithm is robust to noise and can meet the requirement of speed compensation for ISAR imaging under a low SNR condition. Moreover, a fast searching implementation strategy, which consists of coarse search and precise search, has been introduced to decrease the computational burden of speed compensation based on CPF and ICPF. Experimental results based on radar data validate the effectiveness of the proposed algorithms. PMID:26225980

Utility of the Conconi's heart rate deflection to monitor the intensity of aerobic training.

PubMed

Passelergue, Philippe A; Cormery, Bruno; Lac, Gérard; Léger, Luc A

2006-02-01

The Conconi's heart-rate deflection point (HRd) in the heart rate (HR)/speed curve is often used to set aerobic training loads. Training could either be set in percentage running speed or HR at HRd. In order to establish the limits and usefulness of various aerobic-training modalities for intermediate athletic level (physical-education students), acute responses were analyzed while running for a typical 40-minute training session. Speed, HR, lactate, and cortisol were thus recorded during training at 90 and 100% of running speed (RS: n = 14) and HR (HR: n = 16) at HRd (90% running speed [RS90], 100% running speed [RS100], 90% HR [HR90], and 100% HR [HR100]). During constant HR training, RS decreases while HR drifts upward during constant RS training. Half of the subjects can not finish the 40-minute RS100 session. For HR90, RS90, HR100, and RS100, average intensities are 67, 69, 74.9, and 77% maximal aerobic speed (multistage test), respectively. This study indicates that (1) training at HR100 and RS100 is more appropriate to improve high-intensity metabolic capacities (increased cortisol and lactate) while RS100 is too difficult to be maintained for 40 minutes for subjects at that level at least, (2) training at HR90, however, is better to improve endurance and capacity to do a large amount of work considering cortisol and lactate homeostasis, and (3) training at a constant HR using a HR monitor is a good method to control the intensity of the training with subjects not used to pacing themselves with the split-time approach.

Performance Evaluation of FAST TCP Traffic-Flows in Multihomed MANETs

NASA Astrophysics Data System (ADS)

Mudassir, Mumajjed Ul; Akram, Adeel

In Mobile Ad hoc Networks (MANETs) an efficient communication protocol is required at the transport layer. Mobile nodes moving around will have temporary and rather short-lived connectivity with each other and the Internet, thus requiring efficient utilization of network resources. Moreover the problems arising due to high mobility, collision and congestion must also be considered. Multihoming allows higher reliability and enhancement of network throughput. FAST TCP is a new promising transport layer protocol developed for high-speed high-latency networks. In this paper, we have analyzed the performance of FAST TCP traffic flows in multihomed MANETs and compared it with standard TCP (TCP Reno) traffic flows in non-multihomed MANETs.

High-throughput microtitre plate-based assay for DNA topoisomerases.

PubMed

Taylor, James A; Burton, Nicolas P; Maxwell, Anthony

2012-01-01

We have developed a rapid, high-throughput assay for measuring the catalytic activity (DNA supercoiling or relaxation) of DNA topoisomerases. The assay utilizes intermolecular triplex formation between an immobilized triplex-forming oligo (TFO) and a triplex-forming region inserted into the plasmid substrate (pNO1), and capitalizes on the observation that supercoiled DNA forms triplexes more readily than relaxed DNA. Thus, supercoiled DNA is preferentially retained by the TFO under triplex-forming conditions while relaxed DNA can be washed away. Due to its high speed of sample analysis and reduced sample handling over conventional gel-based techniques, this assay can be used to screen chemical libraries for novel inhibitors of topoisomerases.

Femtosecond X-ray diffraction from an aerosolized beam of protein nanocrystals

DOE PAGES

Awel, Salah; Kirian, Richard A.; Wiedorn, Max O.; ...

2018-02-01

High-resolution Bragg diffraction from aerosolized single granulovirus nanocrystals using an X-ray free-electron laser is demonstrated. The outer dimensions of the in-vacuum aerosol injector components are identical to conventional liquid-microjet nozzles used in serial diffraction experiments, which allows the injector to be utilized with standard mountings. As compared with liquid-jet injection, the X-ray scattering background is reduced by several orders of magnitude by the use of helium carrier gas rather than liquid. Such reduction is required for diffraction measurements of small macromolecular nanocrystals and single particles. High particle speeds are achieved, making the approach suitable for use at upcoming high-repetition-rate facilities.

Plasma Oscillation Characterization of NASA's HERMeS Hall Thruster via High Speed Imaging

NASA Technical Reports Server (NTRS)

Huang, Wensheng; Kamhawi, Hani; Haag, Thomas W.

2016-01-01

For missions beyond low Earth orbit, spacecraft size and mass can be dominated by onboard chemical propulsion systems and propellants that may constitute more than 50 percent of the spacecraft mass. This impact can be substantially reduced through the utilization of Solar Electric Propulsion (SEP) due to its substantially higher specific impulse. Studies performed for NASA's Human Exploration and Operations Mission Directorate and Science Mission Directorate have demonstrated that a 50kW-class SEP capability can be enabling for both near term and future architectures and science missions. A high-power SEP element is integral to the Evolvable Mars Campaign, which presents an approach to establish an affordable evolutionary human exploration architecture. To enable SEP missions at the power levels required for these applications, an in-space demonstration of an operational 50kW-class SEP spacecraft has been proposed as a SEP Technology Demonstration Mission (TDM). In 2010 NASA's Space Technology Mission Directorate (STMD) began developing high-power electric propulsion technologies. The maturation of these critical technologies has made mission concepts utilizing high-power SEP viable.

Ultrahigh- and high-speed photography, videography, and photonics '91; Proceedings of the Meeting, San Diego, CA, July 24-26, 1991

NASA Astrophysics Data System (ADS)

Jaanimagi, Paul A.

1992-01-01

This volume presents papers grouped under the topics on advances in streak and framing camera technology, applications of ultrahigh-speed photography, characterizing high-speed instrumentation, high-speed electronic imaging technology and applications, new technology for high-speed photography, high-speed imaging and photonics in detonics, and high-speed velocimetry. The papers presented include those on a subpicosecond X-ray streak camera, photocathodes for ultrasoft X-ray region, streak tube dynamic range, high-speed TV cameras for streak tube readout, femtosecond light-in-flight holography, and electrooptical systems characterization techniques. Attention is also given to high-speed electronic memory video recording techniques, high-speed IR imaging of repetitive events using a standard RS-170 imager, use of a CCD array as a medium-speed streak camera, the photography of shock waves in explosive crystals, a single-frame camera based on the type LD-S-10 intensifier tube, and jitter diagnosis for pico- and femtosecond sources.

Method and system for determining induction motor speed

DOEpatents

Parlos, Alexander G.; Bharadwaj, Raj M.

2004-03-30

A non-linear, semi-parametric neural network-based adaptive filter is utilized to determine the dynamic speed of a rotating rotor within an induction motor, without the explicit use of a speed sensor, such as a tachometer, is disclosed. The neural network-based filter is developed using actual motor current measurements, voltage measurements, and nameplate information. The neural network-based adaptive filter is trained using an estimated speed calculator derived from the actual current and voltage measurements. The neural network-based adaptive filter uses voltage and current measurements to determine the instantaneous speed of a rotating rotor. The neural network-based adaptive filter also includes an on-line adaptation scheme that permits the filter to be readily adapted for new operating conditions during operations.

Differences in energy expenditure during high-speed versus standard-speed yoga: A randomized sequence crossover trial.

PubMed

Potiaumpai, Melanie; Martins, Maria Carolina Massoni; Rodriguez, Roberto; Mooney, Kiersten; Signorile, Joseph F

2016-12-01

To compare energy expenditure and volume of oxygen consumption and carbon dioxide production during a high-speed yoga and a standard-speed yoga program. Randomized repeated measures controlled trial. A laboratory of neuromuscular research and active aging. Sun-Salutation B was performed, for eight minutes, at a high speed versus and a standard-speed separately while oxygen consumption was recorded. Caloric expenditure was calculated using volume of oxygen consumption and carbon dioxide production. Difference in energy expenditure (kcal) of HSY and SSY. Significant differences were observed in energy expenditure between yoga speeds with high-speed yoga producing significantly higher energy expenditure than standard-speed yoga (MD=18.55, SE=1.86, p<0.01). Significant differences were also seen between high-speed and standard-speed yoga for volume of oxygen consumed and carbon dioxide produced. High-speed yoga results in a significantly greater caloric expenditure than standard-speed yoga. High-speed yoga may be an effective alternative program for those targeting cardiometabolic markers. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-speed electro-optic polymers: mm-Wave applications and silica planar lightwave circuit integration

NASA Astrophysics Data System (ADS)

Chang, Daniel H.

The development of high speed polymer electro-optic modulators has seen steady and significant progress in recent years, enabling novel applications in RF-Photonics. Two of these are described in this Thesis: an Opto-Electronic Oscillator (OEO), which is a hybrid RF and optical oscillator capable of high spectral purity, and Photonic Time-Stretch, which is a signal processing technique for waveform spectral shifting with application to photonically-assisted A/D conversion. In both cases, the operating frequencies achieved have been the highest demonstrated to date. Application of this promising material to more complicated devices, however, is stymied by insertion loss performance. Current loss figures, while acceptable for single modulators, are too high for large arrays of modulators or intrinsically long devices such as AWGs or photonic-RF phase shifters. This is especially frustrating in light of a key virtue which polymers possess as a photonic material: its photolithographic process-ability makes patterning complex devices possible. Indeed, the current ascendancy of silica-based waveguide devices can be attributed largely to the same reason. In this Thesis, we also demonstrate the first hybrid device composed of silica planar lightwave circuits (PLCs) and polymer planar waveguides. Our approach utilizes grayscale lithography to enable vertical coupling between polymer and silica layers, minimizing entanglement of their respective fabrication processes. We have achieved coupling excess loss figures on the order of 1dB. We believe this is the natural next step in the development of electro-optic polymer devices. The two technologies are highly complementary. Silica PLCs, with excellent propagation loss and fiber coupling, are ideally suited for long passive waveguiding. By endowing them with the high-speed phase shifting capability offered by polymers, active wideband photonic devices of increasing complexity and array size can be contemplated.

Energy-optimal path planning in the coastal ocean

NASA Astrophysics Data System (ADS)

Subramani, Deepak N.; Haley, Patrick J.; Lermusiaux, Pierre F. J.

2017-05-01

We integrate data-driven ocean modeling with the stochastic Dynamically Orthogonal (DO) level-set optimization methodology to compute and study energy-optimal paths, speeds, and headings for ocean vehicles in the Middle-Atlantic Bight (MAB) region. We hindcast the energy-optimal paths from among exact time-optimal paths for the period 28 August 2006 to 9 September 2006. To do so, we first obtain a data-assimilative multiscale reanalysis, combining ocean observations with implicit two-way nested multiresolution primitive-equation simulations of the tidal-to-mesoscale dynamics in the region. Second, we solve the reduced-order stochastic DO level-set partial differential equations (PDEs) to compute the joint probability of minimum arrival time, vehicle-speed time series, and total energy utilized. Third, for each arrival time, we select the vehicle-speed time series that minimize the total energy utilization from the marginal probability of vehicle-speed and total energy. The corresponding energy-optimal path and headings are obtained through the exact particle-backtracking equation. Theoretically, the present methodology is PDE-based and provides fundamental energy-optimal predictions without heuristics. Computationally, it is 3-4 orders of magnitude faster than direct Monte Carlo methods. For the missions considered, we analyze the effects of the regional tidal currents, strong wind events, coastal jets, shelfbreak front, and other local circulations on the energy-optimal paths. Results showcase the opportunities for vehicles that intelligently utilize the ocean environment to minimize energy usage, rigorously integrating ocean forecasting with optimal control of autonomous vehicles.

Developing course lecture notes on high-speed rail.

DOT National Transportation Integrated Search

2017-07-15

1. Introduction a. World-wide Development of High-Speed Rail (Japan, Europe, China) b. High-speed Rail in the U.S. 2. High-Speed Rail Infrastructure a. Geometric Design of High Speed Rail i. Horizontal Curve ii. Vertical Curve iii. Grade and Turnout ...

Application of Individualized Speed Thresholds to Interpret Position Specific Running Demands in Elite Professional Rugby Union: A GPS Study

PubMed Central

Reardon, Cillian; Tobin, Daniel P.; Delahunt, Eamonn

2015-01-01

A number of studies have used GPS technology to categorise rugby union locomotive demands. However, the utility of the results of these studies is confounded by small sample sizes, sub-elite player status and the global application of absolute speed thresholds to all player positions. Furthermore, many of these studies have used GPS units with low sampling frequencies. The aim of the present study was to compare and contrast the high speed running (HSR) demands of professional rugby union when utilizing micro-technology units sampling at 10 Hz and applying relative or individualised speed zones. The results of this study indicate that application of individualised speed zones results in a significant shift in the interpretation of the HSR demands of both forwards and backs and positional sub-categories therein. When considering the use of an absolute in comparison to an individualised HSR threshold, there was a significant underestimation for forwards of HSR distance (HSRD) (absolute = 269 ± 172.02, individualised = 354.72 ± 99.22, p < 0.001), HSR% (absolute = 5.15 ± 3.18, individualised = 7.06 ± 2.48, p < 0.001) and HSR efforts (HSRE) (absolute = 18.81 ± 12.25; individualised = 24.78 ± 8.30, p < 0.001). In contrast, there was a significant overestimation of the same HSR metrics for backs with the use of an absolute threshold (HSRD absolute = 697.79 ± 198.11, individualised = 570.02 ± 171.14, p < 0.001; HSR% absolute = 10.85 ± 2.82, individualised = 8.95 ± 2.76, p < 0.001; HSRE absolute = 41.55 ± 11.25; individualised = 34.54 ± 9.24, p < 0.001). This under- or overestimation associated with an absolute speed zone applies to varying degrees across the ten positional sub-categories analyzed and also to individuals within the same positional sub-category. The results of the present study indicated that although use of an individulised HSR threshold improves the interpretation of the HSR demands on a positional basis, inter-individual variability in maximum velocity within positional sub-categories means that players need to be considered on an individual basis to accurately gauge the HSR demands of rugby union. PMID:26208315

Variable-Speed Simulation of a Dual-Clutch Gearbox Tiltrotor Driveline

NASA Technical Reports Server (NTRS)

DeSmidt, Hans; Wang, Kon-Well; Smith, Edward C.; Lewicki, David G.

2012-01-01

This investigation explores the variable-speed operation and shift response of a prototypical two-speed dual-clutch transmission tiltrotor driveline in forward flight. Here, a Comprehensive Variable-Speed Rotorcraft Propulsion System Modeling (CVSRPM) tool developed under a NASA funded NRA program is utilized to simulate the drive system dynamics. In this study, a sequential shifting control strategy is analyzed under a steady forward cruise condition. This investigation attempts to build upon previous variable-speed rotorcraft propulsion studies by 1) including a fully nonlinear transient gas-turbine engine model, 2) including clutch stick-slip friction effects, 3) including shaft flexibility, 4) incorporating a basic flight dynamics model to account for interactions with the flight control system. Through exploring the interactions between the various subsystems, this analysis provides important insights into the continuing development of variable-speed rotorcraft propulsion systems.

A Rotational Gyroscope with a Water-Film Bearing Based on Magnetic Self-Restoring Effect

PubMed Central

Chen, Dianzhong; Liu, Xiaowei; Li, Hai; Li, Ling; Rong, Wanting; Zhang, Zhongzhao

2018-01-01

Stable rotor levitation is a challenge for rotational gyroscopes (magnetically suspended gyroscopes (MSG) and electrostatically suspended gyroscopes (ESG)) with a ring- or disk-shaped rotor, which restricts further improvement of gyroscope performance. In addition, complicated pick-up circuits and feedback control electronics propose high requirement on fabrication technology. In the proposed gyroscope, a ball-disk shaped rotor is supported by a water-film bearing, formed by centrifugal force to deionized water at the cavity of the lower supporting pillar. Water-film bearing provides stable mechanical support, without the need for complicated electronics and control system for rotor suspension. To decrease sliding friction between the rotor ball and the water-film bearing, a supherhydrophobic surface (SHS) with nano-structures is fabricated on the rotor ball, resulting in a rated spinning speed increase of 12.4% (under the same driving current). Rotor is actuated by the driving scheme of brushless direct current motor (BLDCM). Interaction between the magnetized rotor and the magnetic-conducted stator produces a sinusoidal rotor restoring torque, amplitude of which is proportional to the rotor deflection angle inherently. Utilization of this magnetic restoring effect avoids adding of a high amplitude voltage for electrostatic feedback, which may cause air breakdown. Two differential capacitance pairs are utilized to measure input angular speeds at perpendicular directions of the rotor plane. The bias stability of the fabricated gyroscope is as low as 0.5°/h. PMID:29385105

Client/Server data serving for high performance computing

NASA Technical Reports Server (NTRS)

Wood, Chris

1994-01-01

This paper will attempt to examine the industry requirements for shared network data storage and sustained high speed (10's to 100's to thousands of megabytes per second) network data serving via the NFS and FTP protocol suite. It will discuss the current structural and architectural impediments to achieving these sorts of data rates cost effectively today on many general purpose servers and will describe and architecture and resulting product family that addresses these problems. The sustained performance levels that were achieved in the lab will be shown as well as a discussion of early customer experiences utilizing both the HIPPI-IP and ATM OC3-IP network interfaces.

Smart Optical RAM for Fast Information Management and Analysis

NASA Technical Reports Server (NTRS)

Liu, Hua-Kuang

1998-01-01

Statement of Problem Instruments for high speed and high capacity in-situ data identification, classification and storage capabilities are needed by NASA for the information management and analysis of extremely large volume of data sets in future space exploration, space habitation and utilization, in addition to the various missions to planet-earth programs. Parameters such as communication delays, limited resources, and inaccessibility of human manipulation require more intelligent, compact, low power, and light weight information management and data storage techniques. New and innovative algorithms and architecture using photonics will enable us to meet these challenges. The technology has applications for other government and public agencies.

The most intense current sheets in the high-speed solar wind near 1 AU

NASA Astrophysics Data System (ADS)

Podesta, John J.

2017-03-01

Electric currents in the solar wind plasma are investigated using 92 ms fluxgate magnetometer data acquired in a high-speed stream near 1 AU. The minimum resolvable scale is roughly 0.18 s in the spacecraft frame or, using Taylor's "frozen turbulence" approximation, one proton inertial length di in the plasma frame. A new way of identifying current sheets is developed that utilizes a proxy for the current density J obtained from the derivatives of the three orthogonal components of the observed magnetic field B. The most intense currents are identified as 5σ events, where σ is the standard deviation of the current density. The observed 5σ events are characterized by an average scale size of approximately 3di along the flow direction of the solar wind, a median separation of around 50di or 100di along the flow direction of the solar wind, and a peak current density on the order of 0.5 pA/cm2. The associated current-carrying structures are consistent with current sheets; however, the planar geometry of these structures cannot be confirmed using single-point, single-spacecraft measurements. If Taylor's hypothesis continues to hold for the energetically dominant fluctuations at kinetic scales 1

Fast packet switching algorithms for dynamic resource control over ATM networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsang, R.P.; Keattihananant, P.; Chang, T.

1996-12-01

Real-time continuous media traffic, such as digital video and audio, is expected to comprise a large percentage of the network load on future high speed packet switch networks such as ATM. A major feature which distinguishes high speed networks from traditional slower speed networks is the large amount of data the network must process very quickly. For efficient network usage, traffic control mechanisms are essential. Currently, most mechanisms for traffic control (such as flow control) have centered on the support of Available Bit Rate (ABR), i.e., non real-time, traffic. With regard to ATM, for ABR traffic, two major types ofmore » schemes which have been proposed are rate- control and credit-control schemes. Neither of these schemes are directly applicable to Real-time Variable Bit Rate (VBR) traffic such as continuous media traffic. Traffic control for continuous media traffic is an inherently difficult problem due to the time- sensitive nature of the traffic and its unpredictable burstiness. In this study, we present a scheme which controls traffic by dynamically allocating/de- allocating resources among competing VCs based upon their real-time requirements. This scheme incorporates a form of rate- control, real-time burst-level scheduling and link-link flow control. We show analytically potential performance improvements of our rate- control scheme and present a scheme for buffer dimensioning. We also present simulation results of our schemes and discuss the tradeoffs inherent in maintaining high network utilization and statistically guaranteeing many users` Quality of Service.« less

High Technology Centrifugal Compressor for Commercial Air Conditioning Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruckes, John

2006-04-15

R&D Dynamics, Bloomfield, CT in partnership with the State of Connecticut has been developing a high technology, oil-free, energy-efficient centrifugal compressor called CENVA for commercial air conditioning systems under a program funded by the US Department of Energy. The CENVA compressor applies the foil bearing technology used in all modern aircraft, civil and military, air conditioning systems. The CENVA compressor will enhance the efficiency of water and air cooled chillers, packaged roof top units, and other air conditioning systems by providing an 18% reduction in energy consumption in the unit capacity range of 25 to 350 tons of refrigeration Themore » technical approach for CENVA involved the design and development of a high-speed, oil-free foil gas bearing-supported two-stage centrifugal compressor, CENVA encompassed the following high technologies, which are not currently utilized in commercial air conditioning systems: Foil gas bearings operating in HFC-134a; Efficient centrifugal impellers and diffusers; High speed motors and drives; and System integration of above technologies. Extensive design, development and testing efforts were carried out. Significant accomplishments achieved under this program are: (1) A total of 26 builds and over 200 tests were successfully completed with successively improved designs; (2) Use of foil gas bearings in refrigerant R134a was successfully proven; (3) A high speed, high power permanent magnet motor was developed; (4) An encoder was used for signal feedback between motor and controller. Due to temperature limitations of the encoder, the compressor could not operate at higher speed and in turn at higher pressure. In order to alleviate this problem a unique sensorless controller was developed; (5) This controller has successfully been tested as stand alone; however, it has not yet been integrated and tested as a system; (6) The compressor successfully operated at water cooled condensing temperatures Due to temperature limitations of the encoder, it could not be operated at air cooled condensing temperatures. (7) The two-stage impellers/diffusers worked well separately but combined did not match well.« less

A compact high-speed mechanical sample shuttle for field-dependent high-resolution solution NMR

NASA Astrophysics Data System (ADS)

Chou, Ching-Yu; Chu, Minglee; Chang, Chi-Fon; Huang, Tai-huang

2012-01-01

Analysis of NMR relaxation data has provided significant insight on molecular dynamic, leading to a more comprehensive understanding of macromolecular functions. However, traditional methodology allows relaxation measurements performed only at a few fixed high fields, thus severely restricting their potential for extracting more complete dynamic information. Here we report the design and performance of a compact high-speed servo-mechanical shuttle assembly adapted to a commercial 600 MHz high-field superconducting magnet. The assembly is capable of shuttling the sample in a regular NMR tube from the center of the magnet to the top (fringe field ˜0.01 T) in 100 ms with no loss of sensitivity other than that due to intrinsic relaxation. The shuttle device can be installed by a single experienced user in 30 min. Excellent 2D- 15N-HSQC spectra of (u- 13C, 15N)-ubiquitin with relaxation at low fields (3.77 T) and detection at 14.1 T were obtained to illustrate its utility in R 1 measurements of macromolecules at low fields. Field-dependent 13C-R 1 data of (3,3,3-d)-alanine at various field strengths were determined and analyzed to assess CSA and 1H- 13C dipolar contributions to the carboxyl 13C-R 1.

Magnetic characterization of the stator core of a high-speed motor made of an ultrathin electrical steel sheet using the magnetic property evaluation system

NASA Astrophysics Data System (ADS)

Oka, Mohachiro; Enokizono, Masato; Mori, Yuji; Yamazaki, Kazumasa

2018-04-01

Recently, the application areas for electric motors have been expanding. For instance, electric motors are used in new technologies such as rovers, drones, cars, and robots. The motor used in such machinery should be small, high-powered, highly-efficient, and high-speed. In such motors, loss at high-speed rotation must be especially minimal. Eddy-current loss in the stator core is known to increase greatly during loss at high-speed rotation of the motor. To produce an efficient high-speed motor, we are developing a stator core for a motor using an ultrathin electrical steel sheet with only a small amount of eddy-current loss. Furthermore, the magnetic property evaluation for efficient, high-speed motor stator cores that use conventional commercial frequency is insufficient. Thus, we made a new high-speed magnetic property evaluation system to evaluate the magnetic properties of the efficient high-speed motor stator core. This system was composed of high-speed A/D converters, D/A converters, and a high-speed power amplifier. In experiments, the ultrathin electrical steel sheet dramatically suppressed iron loss and, in particular, eddy-current loss. In addition, a new high-speed magnetic property evaluation system accurately evaluated the magnetic properties of the efficient high-speed motor stator core.

A hybrid short read mapping accelerator

PubMed Central

2013-01-01

Background The rapid growth of short read datasets poses a new challenge to the short read mapping problem in terms of sensitivity and execution speed. Existing methods often use a restrictive error model for computing the alignments to improve speed, whereas more flexible error models are generally too slow for large-scale applications. A number of short read mapping software tools have been proposed. However, designs based on hardware are relatively rare. Field programmable gate arrays (FPGAs) have been successfully used in a number of specific application areas, such as the DSP and communications domains due to their outstanding parallel data processing capabilities, making them a competitive platform to solve problems that are “inherently parallel”. Results We present a hybrid system for short read mapping utilizing both FPGA-based hardware and CPU-based software. The computation intensive alignment and the seed generation operations are mapped onto an FPGA. We present a computationally efficient, parallel block-wise alignment structure (Align Core) to approximate the conventional dynamic programming algorithm. The performance is compared to the multi-threaded CPU-based GASSST and BWA software implementations. For single-end alignment, our hybrid system achieves faster processing speed than GASSST (with a similar sensitivity) and BWA (with a higher sensitivity); for pair-end alignment, our design achieves a slightly worse sensitivity than that of BWA but has a higher processing speed. Conclusions This paper shows that our hybrid system can effectively accelerate the mapping of short reads to a reference genome based on the seed-and-extend approach. The performance comparison to the GASSST and BWA software implementations under different conditions shows that our hybrid design achieves a high degree of sensitivity and requires less overall execution time with only modest FPGA resource utilization. Our hybrid system design also shows that the performance bottleneck for the short read mapping problem can be changed from the alignment stage to the seed generation stage, which provides an additional requirement for the future development of short read aligners. PMID:23441908

Cooling system for high speed aircraft

NASA Technical Reports Server (NTRS)

Lawing, P. L.; Pagel, L. L. (Inventor)

1981-01-01

The system eliminates the necessity of shielding an aircraft airframe constructed of material such as aluminum. Cooling is accomplished by passing a coolant through the aircraft airframe, the coolant acting as a carrier to remove heat from the airframe. The coolant is circulated through a heat pump and a heat exchanger which together extract essentially all of the added heat from the coolant. The heat is transferred to the aircraft fuel system via the heat exchanger and the heat pump. The heat extracted from the coolant is utilized to power the heat pump. The heat pump has associated therewith power turbine mechanism which is also driven by the extracted heat. The power turbines are utilized to drive various aircraft subsystems, the compressor of the heat pump, and provide engine cooling.

Landsat-Swath Imaging Spectrometer Design

NASA Technical Reports Server (NTRS)

Mouroulis, Pantazis; Green, Robert O.; Van Gorp, Byron; Moore, Lori; Wilson, Daniel W.; Bender, Holly A.

2015-01-01

We describe the design of a high-throughput pushbroom imaging spectrometer and telescope system that is capable of Landsat swath and resolution while providing better than 10 nm per pixel spectral resolution. The design is based on a 3200 x 480 element x 18 µm pixel size focal plane array, two of which are utilized to cover the full swath. At an optical speed of F/1.8, the system is the fastest proposed to date to our knowledge. The utilization of only two spectrometer modules fed from the same telescope reduces system complexity while providing a solution within achievable detector technology. Predictions of complete system response are shown. Also, it is shown that detailed ghost analysis is a requirement for this type of spectrometer and forms an essential part of a complete design.

78 FR 22031 - California High-Speed Rail Authority-Construction Exemption-In Merced, Madera and Fresno Counties...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-12

... High-Speed Rail Authority--Construction Exemption--In Merced, Madera and Fresno Counties, CA AGENCY... High-Speed Rail Authority (Authority). This Final EIS is titled ``California High-Speed Train: Merced... Final EIS assesses the potential environmental impacts of constructing and operating a high-speed...

Speed-of-Sound Measurements in (Argon + Carbon Dioxide) over the Temperature Range from (275 to 500) K at Pressures up to 8 MPa.

PubMed

Wegge, Robin; McLinden, Mark O; Perkins, Richard A; Richter, Markus; Span, Roland

2016-08-01

The speed of sound of two (argon + carbon dioxide) mixtures was measured over the temperature range from (275 to 500) K with pressures up to 8 MPa utilizing a spherical acoustic resonator. The compositions of the gravimetrically prepared mixtures were (0.50104 and 0.74981) mole fraction carbon dioxide. The vibrational relaxation of pure carbon dioxide led to high sound absorption, which significantly impeded the sound-speed measurements on carbon dioxide and its mixtures; pre-condensation may have also affected the results for some measurements near the dew line. Thus, in contrast to the standard operating procedure for speed-of-sound measurements with a spherical resonator, non-radial resonances at lower frequencies were taken into account. Still, the data show a comparatively large scatter, and the usual repeatability of this general type of instrument could not be realized with the present measurements. Nonetheless, the average relative combined expanded uncertainty ( k = 2) in speed of sound ranged from (0.042 to 0.056)% for both mixtures, with individual state-point uncertainties increasing to 0.1%. These uncertainties are adequate for our intended purpose of evaluating thermodynamic models. The results are compared to a Helmholtz energy equation of state for carbon capture and storage applications; relative deviations of (-0.64 to 0.08)% for the (0.49896 argon + 0.50104 carbon dioxide) mixture, and of (-1.52 to 0.77)% for the (0.25019 argon + 0.74981 carbon dioxide) mixture were observed.

Estimation of the high-spatial-resolution variability in extreme wind speeds for forestry applications

NASA Astrophysics Data System (ADS)

Venäläinen, Ari; Laapas, Mikko; Pirinen, Pentti; Horttanainen, Matti; Hyvönen, Reijo; Lehtonen, Ilari; Junila, Päivi; Hou, Meiting; Peltola, Heli M.

2017-07-01

The bioeconomy has an increasing role to play in climate change mitigation and the sustainable development of national economies. In Finland, a forested country, over 50 % of the current bioeconomy relies on the sustainable management and utilization of forest resources. Wind storms are a major risk that forests are exposed to and high-spatial-resolution analysis of the most vulnerable locations can produce risk assessment of forest management planning. In this paper, we examine the feasibility of the wind multiplier approach for downscaling of maximum wind speed, using 20 m spatial resolution CORINE land-use dataset and high-resolution digital elevation data. A coarse spatial resolution estimate of the 10-year return level of maximum wind speed was obtained from the ERA-Interim reanalyzed data. Using a geospatial re-mapping technique the data were downscaled to 26 meteorological station locations to represent very diverse environments. Applying a comparison, we find that the downscaled 10-year return levels represent 66 % of the observed variation among the stations examined. In addition, the spatial variation in wind-multiplier-downscaled 10-year return level wind was compared with the WAsP model-simulated wind. The heterogeneous test area was situated in northern Finland, and it was found that the major features of the spatial variation were similar, but in some locations, there were relatively large differences. The results indicate that the wind multiplier method offers a pragmatic and computationally feasible tool for identifying at a high spatial resolution those locations with the highest forest wind damage risks. It can also be used to provide the necessary wind climate information for wind damage risk model calculations, thus making it possible to estimate the probability of predicted threshold wind speeds for wind damage and consequently the probability (and amount) of wind damage for certain forest stand configurations.

Method and means for generating a synchronizing pulse from a repetitive wave of varying frequency

DOEpatents

DeVolpi, Alexander; Pecina, Ronald J.; Travis, Dale J.

1976-01-01

An event that occurs repetitively at continuously changing frequencies can be used to generate a triggering pulse which is used to synchronize or control. The triggering pulse is generated at a predetermined percentage of the period of the repetitive waveform without regard to frequency. Counts are accumulated in two counters, the first counting during the "on" fraction of the period, and the second counting during the "off" fraction. The counts accumulated during each cycle are compared. On equality the trigger pulse is generated. Count input rates to each counter are determined by the ratio of the on-off fractions of the event waveform and the desired phase relationship. This invention is of particular utility in providing a trigger or synchronizing pulse during the open period of the shutter of a high-speed framing camera during its acceleration as well as its period of substantially constant speed.

Balloon launched decelerator test program: Post-test test report

NASA Technical Reports Server (NTRS)

Dickinson, D.; Schlemmer, J.; Hicks, F.; Michel, F.; Moog, R. D.

1972-01-01

Balloon Launched Decelerator Test (BLDT) flights were conducted during the summer of 1972 over the White Sands Missile Range. The purpose of these tests was to qualify the Viking disk-gap band parachute system behind a full-scale simulator of the Viking Entry Vehicle over the maximum range of entry conditions anticipated in the Viking '75 soft landing on Mars. Test concerns centered on the ability of a minimum weight parachute system to operate without structural damage in the turbulent wake of the blunt-body entry vehicle (140 deg, 11.5 diameter cone). This is the first known instance of parachute operation at supersonic speeds in the wake of such a large blunt body. The flight tests utilized the largest successful balloon-payload weight combination known to get to high altitude (120kft) where rocket engines were employed to boost the test vehicle to supersonic speeds and dynamic pressures simulating the range of conditions on Mars.

Cranz-Schardin camera with a large working distance for the observation of small scale high-speed flows.

PubMed

Skupsch, C; Chaves, H; Brücker, C

2011-08-01

The Cranz-Schardin camera utilizes a Q-switched Nd:YAG laser and four single CCD cameras. Light pulse energy in the range of 25 mJ and pulse duration of about 5 ns is provided by the laser. The laser light is converted to incoherent light by Rhodamine-B fluorescence dye in a cuvette. The laser beam coherence is intentionally broken in order to avoid speckle. Four light fibers collect the fluorescence light and are used for illumination. Different light fiber lengths enable a delay of illumination between consecutive images. The chosen interframe time is 25 ns, corresponding to 40 × 10(6) frames per second. Exemplarily, the camera is applied to observe the bow shock in front of a water jet, propagating in air at supersonic speed. The initial phase of the formation of a jet structure is recorded.

Modeling the effect of control on the wake of a utility-scale turbine via large-eddy simulation

NASA Astrophysics Data System (ADS)

Yang, Xiaolei; Annoni, Jennifer; Seiler, Pete; Sotiropoulos, Fotis

2014-06-01

A model of the University of Minnesota EOLOS research turbine (Clipper Liberty C96) is developed, integrating the C96 torque control law with a high fidelity actuator line large- eddy simulation (LES) model. Good agreement with the blade element momentum theory is obtained for the power coefficient curve under uniform inflow. Three different cases, fixed rotor rotational speed ω, fixed tip-speed ratio (TSR) and generator torque control, have been simulated for turbulent inflow. With approximately the same time-averaged ω, the time- averaged power is in good agreement with measurements for all three cases. Although the time-averaged aerodynamic torque is nearly the same for the three cases, the root-mean-square (rms) of the aerodynamic torque fluctuations is significantly larger for the case with fixed ω. No significant differences have been observed for the time-averaged flow fields behind the turbine for these three cases.

Pool boiling from rotating and stationary spheres in liquid nitrogen

NASA Technical Reports Server (NTRS)

Cuan, Winston M.; Schwartz, Sidney H.

1988-01-01

Results are presented for a preliminary experiment involving saturated pool boiling at 1 atm from rotating 2 and 3 in. diameter spheres which were immersed in liquid nitrogen (LN2). Additional results are presented for a stationary, 2 inch diameter sphere, quenched in LN2, which were obtained utilizing a more versatile and complete experimental apparatus that will eventually be used for additional rotating sphere experiments. The speed for the rotational tests was varied from 0 to 10,000 rpm. The stationary experiments parametrically varied pressure and subcooling levels from 0 to 600 psig and from 0 to 50 F, respectively. During the rotational tests, a high speed photographic analysis was undertaken to measure the thickness of the vapor film surrounding the sphere. The average Nusselt number over the cooling period was plotted against the rotational Reynolds number. Stationary sphere results included local boiling heat transfer coefficients at different latitudinal locations, for various pressure and subcooling levels.

Gas turbine power plant with supersonic shock compression ramps

DOEpatents

Lawlor, Shawn P [Bellevue, WA; Novaresi, Mark A [San Diego, CA; Cornelius, Charles C [Kirkland, WA

2008-10-14

A gas turbine engine. The engine is based on the use of a gas turbine driven rotor having a compression ramp traveling at a local supersonic inlet velocity (based on the combination of inlet gas velocity and tangential speed of the ramp) which compresses inlet gas against a stationary sidewall. The supersonic compressor efficiently achieves high compression ratios while utilizing a compact, stabilized gasdynamic flow path. Operated at supersonic speeds, the inlet stabilizes an oblique/normal shock system in the gasdynamic flow path formed between the rim of the rotor, the strakes, and a stationary external housing. Part load efficiency is enhanced by use of a lean pre-mix system, a pre-swirl compressor, and a bypass stream to bleed a portion of the gas after passing through the pre-swirl compressor to the combustion gas outlet. Use of a stationary low NOx combustor provides excellent emissions results.

Rotor redesign for a highly loaded 1800 ft/sec tip speed fan, 2

NASA Technical Reports Server (NTRS)

Bolt, C. R.

1980-01-01

Tests were conducted on a 0.5 hub/tip ratio single-stage fan designed to produce a pressure ratio of 2.280 at an efficiency of 83.8 percent with a rotor tip speed of 548.6 m/sec (1800 ft/sec). The rotor was designed utilizing a quasi three dimensional design system and four-part, multiple-circular-arc airfoil sections. The rotor is the third in a series of single-stage fans that have included a precompression airfoil design and a multiple-circular-arc airfoil design. The stage achieved a peak efficiency of 82.8 percent after performance had deteriorated by 0.6 of a point. The design mass flow was achieved at the peak efficiency point, and the stage total pressure ratio was 2.20, which is lower than the design goal of 2.28. The surge margin of 13% from the peak efficiency point exceeded the design goal of 7%.

33 CFR 169.5 - How are terms used in this part defined?

Code of Federal Regulations, 2011 CFR

2011-07-01

... § 169.15). Gross tons means vessel tonnage measured in accordance with the method utilized by the flag... water and is capable of a maximum speed equal to or exceeding V=3.7×displ .1667, where “V” is the maximum speed and “displ” is the vessel displacement corresponding to the design waterline in cubic meters...

33 CFR 169.5 - How are terms used in this part defined?

Code of Federal Regulations, 2012 CFR

2012-07-01

... § 169.15). Gross tons means vessel tonnage measured in accordance with the method utilized by the flag... water and is capable of a maximum speed equal to or exceeding V=3.7×displ .1667, where “V” is the maximum speed and “displ” is the vessel displacement corresponding to the design waterline in cubic meters...

33 CFR 169.5 - How are terms used in this part defined?

Code of Federal Regulations, 2013 CFR

2013-07-01

... § 169.15). Gross tons means vessel tonnage measured in accordance with the method utilized by the flag... water and is capable of a maximum speed equal to or exceeding V=3.7×displ .1667, where “V” is the maximum speed and “displ” is the vessel displacement corresponding to the design waterline in cubic meters...

33 CFR 169.5 - How are terms used in this part defined?

Code of Federal Regulations, 2014 CFR

2014-07-01

... § 169.15). Gross tons means vessel tonnage measured in accordance with the method utilized by the flag... water and is capable of a maximum speed equal to or exceeding V=3.7×displ .1667, where “V” is the maximum speed and “displ” is the vessel displacement corresponding to the design waterline in cubic meters...

A preliminary study of the benefits of flying by ground speed during final approach

NASA Technical Reports Server (NTRS)

Hastings, E. C., Jr.

1978-01-01

A study was conducted to evaluate the benefits of an approach technique which utilized constant ground speed on approach. It was determined that the technique reduced the capacity losses in headwinds experienced with the currently used constant airspeed technique. The benefits of technique were found to increase as headwinds increased and as the wake avoidance separation intervals were reduced. An additional benefit noted for the constant ground speed technique was a reduction in stopping distance variance due to the approach wind environment.

Induction motor speed control using varied duty cycle terminal voltage via PI controller

NASA Astrophysics Data System (ADS)

Azwin, A.; Ahmed, S.

2018-03-01

This paper deals with the PI speed controller for the three-phase induction motor using PWM technique. The PWM generated signal is utilized for voltage source inverter with an optimal duty cycle on a simplified induction motor model. A control algorithm for generating PWM control signal is developed. Obtained results shows that the steady state error and overshoot of the developed system is in the limit under different speed and load condition. The robustness of the control performance would be potential for induction motor performance improvement.

Automated assessment of blood flow in developing embryonic hearts by extending dynamic range of Doppler OCT using a MHz FDML swept laser source (Conference Presentation)

NASA Astrophysics Data System (ADS)

Elahi, Sahar; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

2017-02-01

Altered hemodynamics in developing embryonic hearts lead to congenital heart diseases, motivating close monitoring of blood flow over several stages of development. Doppler OCT can assess blood flow in tubular hearts, but the maximum velocity increases drastically during the period of cardiac cushion (valve precursors) formation. Therefore, the limited dynamic range of Doppler OCT velocity measurement makes it difficult to conduct longitudinal studies without phase wrapping at high velocities or loss of sensitivity to slow velocities. We have built a high-speed OCT system using an FDML laser (Optores GmbH, Germany) at a sweep rate of 1.68 MHz (axial resolution - 12 μm, sensitivity - 105 dB, phase stability - 17 mrad). The speed of this OCT system allows us to acquire high-density B-scans to obtain an extended velocity dynamic range without sacrificing the frame rate. The extended dynamic range within a frame is achieved by varying the A-scan interval at which the phase difference is found, enabling detection of velocities ranging from tens of microns per second to hundreds of mm per second. The extra lines in a frame can also be utilized to improve the structural and Doppler images via complex averaging. In structural images where presence of blood causes additional scattering, complex averaging helps retrieve features located deeper in the tissue. Moreover, high-density frames can be registered to 4D volumes to determine the orthogonal direction of flow and calculate shear stress. In conclusion, our high-speed OCT system will enable automated Doppler imaging of embryonic hearts in cohort studies.

Field and laboratory comparison of PM10 instruments in high winds

NASA Astrophysics Data System (ADS)

Sharratt, Brenton; Pi, Huawei

2018-06-01

Instruments capable of measuring PM10 (particulate matter ≤10 μm in aerodynamic diameter) concentrations may vary in performance as a result of different technologies utilized in measuring PM10. Therefore, the performance of five instruments capable of measuring PM10 concentrations above eroding soil surfaces was tested during high wind events at field sites in the Columbia Plateau and inside a wind tunnel. Comparisons among the Big Spring Number Eight (BSNE) sampler, DustTrak monitor, E-sampler, High-Volume sampler, and Tapered Element Oscillating Microbalance (TEOM) monitor were made at field sites during nine wind erosion events and inside a wind tunnel at two wind speeds (7 and 12 m s-1) and two ambient PM10 concentrations (2 and 50 mg m-3). PM10 concentrations were similar for the High-Volume sampler and TEOM monitor as well as for the BSNE samplers and DustTrak monitors but higher for the High-Volume sampler and TEOM monitor than the E-sampler during field erosion events. Based upon wind tunnel experiments, the TEOM monitor measured the highest PM10 concentration while the DustTrak monitor typically measured the lowest PM10 concentration as compared with other instruments. In addition, PM10 concentration appeared to lower for all instruments at a wind speed of 12 as compared with 7 m s-1 inside the wind tunnel. Differences in the performance of instruments in measuring PM10 concentration poses risks in comparing PM10 concentration among different instrument types or using multiple instrument types to jointly measure concentrations in the field or laboratory or even the same instrument type subject to different wind speeds.

Radial polar histogram: obstacle avoidance and path planning for robotic cognition and motion control

NASA Astrophysics Data System (ADS)

Wang, Po-Jen; Keyawa, Nicholas R.; Euler, Craig

2012-01-01

In order to achieve highly accurate motion control and path planning for a mobile robot, an obstacle avoidance algorithm that provided a desired instantaneous turning radius and velocity was generated. This type of obstacle avoidance algorithm, which has been implemented in California State University Northridge's Intelligent Ground Vehicle (IGV), is known as Radial Polar Histogram (RPH). The RPH algorithm utilizes raw data in the form of a polar histogram that is read from a Laser Range Finder (LRF) and a camera. A desired open block is determined from the raw data utilizing a navigational heading and an elliptical approximation. The left and right most radii are determined from the calculated edges of the open block and provide the range of possible radial paths the IGV can travel through. In addition, the calculated obstacle edge positions allow the IGV to recognize complex obstacle arrangements and to slow down accordingly. A radial path optimization function calculates the best radial path between the left and right most radii and is sent to motion control for speed determination. Overall, the RPH algorithm allows the IGV to autonomously travel at average speeds of 3mph while avoiding all obstacles, with a processing time of approximately 10ms.

GSRP/David Marshall: Fully Automated Cartesian Grid CFD Application for MDO in High Speed Flows

NASA Technical Reports Server (NTRS)

2003-01-01

With the renewed interest in Cartesian gridding methodologies for the ease and speed of gridding complex geometries in addition to the simplicity of the control volumes used in the computations, it has become important to investigate ways of extending the existing Cartesian grid solver functionalities. This includes developing methods of modeling the viscous effects in order to utilize Cartesian grids solvers for accurate drag predictions and addressing the issues related to the distributed memory parallelization of Cartesian solvers. This research presents advances in two areas of interest in Cartesian grid solvers, viscous effects modeling and MPI parallelization. The development of viscous effects modeling using solely Cartesian grids has been hampered by the widely varying control volume sizes associated with the mesh refinement and the cut cells associated with the solid surface. This problem is being addressed by using physically based modeling techniques to update the state vectors of the cut cells and removing them from the finite volume integration scheme. This work is performed on a new Cartesian grid solver, NASCART-GT, with modifications to its cut cell functionality. The development of MPI parallelization addresses issues associated with utilizing Cartesian solvers on distributed memory parallel environments. This work is performed on an existing Cartesian grid solver, CART3D, with modifications to its parallelization methodology.

High-Energy Two-Stage Pulsed Plasma Thruster

NASA Technical Reports Server (NTRS)

Markusic, Tom

2003-01-01

A high-energy (28 kJ per pulse) two-stage pulsed plasma thruster (MSFC PPT-1) has been constructed and tested. The motivation of this project is to develop a high power (approximately 500 kW), high specific impulse (approximately 10000 s), highly efficient (greater than 50%) thruster for use as primary propulsion in a high power nuclear electric propulsion system. PPT-1 was designed to overcome four negative characteristics which have detracted from the utility of pulsed plasma thrusters: poor electrical efficiency, poor propellant utilization efficiency, electrode erosion, and reliability issues associated with the use of high speed gas valves and high current switches. Traditional PPTs have been plagued with poor efficiency because they have not been operated in a plasma regime that fully exploits the potential benefits of pulsed plasma acceleration by electromagnetic forces. PPTs have generally been used to accelerate low-density plasmas with long current pulses. Operation of thrusters in this plasma regime allows for the development of certain undesirable particle-kinetic effects, such as Hall effect-induced current sheet canting. PPT-1 was designed to propel a highly collisional, dense plasma that has more fluid-like properties and, hence, is more effectively pushed by a magnetic field. The high-density plasma loading into the second stage of the accelerator is achieved through the use of a dense plasma injector (first stage). The injector produces a thermal plasma, derived from a molten lithium propellant feed system, which is subsequently accelerated by the second stage using mega-amp level currents, which eject the plasma at a speed on the order of 100 kilometers per second. Traditional PPTs also suffer from dynamic efficiency losses associated with snowplow loading of distributed neutral propellant. The twostage scheme used in PPT-I allows the propellant to be loaded in a manner which more closely approximates the optimal slug loading. Lithium propellant was chosen to test whether or not the reduced electrode erosion found in the Lithium Lorentz Force Accelerator (LiLFA) could also be realized in a pulsed plasma thruster. The use of the molten lithium dense plasma injector also eliminates the need for a gas valve and electrical switch; the injector design fulfills both roles, and uses no moving parts to provide, in principle, a highly reliable propellant feed and electrical switching system. Experimental results reported in this paper include: second-stage current traces, high-speed photographic and holographic imaging of the thruster exit plume, and internal mapping of the discharge chamber magnetic field from B-dot probe data. The magnetic field data is used to create a two-dimensional description of the evolution of the current sheet inside the thruster.

Hardware implementation of CMAC neural network with reduced storage requirement.

PubMed

Ker, J S; Kuo, Y H; Wen, R C; Liu, B D

1997-01-01

The cerebellar model articulation controller (CMAC) neural network has the advantages of fast convergence speed and low computation complexity. However, it suffers from a low storage space utilization rate on weight memory. In this paper, we propose a direct weight address mapping approach, which can reduce the required weight memory size with a utilization rate near 100%. Based on such an address mapping approach, we developed a pipeline architecture to efficiently perform the addressing operations. The proposed direct weight address mapping approach also speeds up the computation for the generation of weight addresses. Besides, a CMAC hardware prototype used for color calibration has been implemented to confirm the proposed approach and architecture.

71-Mbit/s ultraviolet-B LED communication link based on 8-QAM-OFDM modulation.

PubMed

Sun, Xiaobin; Zhang, Zhenyu; Chaaban, Anas; Ng, Tien Khee; Shen, Chao; Chen, Rui; Yan, Jianchang; Sun, Haiding; Li, Xiaohang; Wang, Junxi; Li, Jinmin; Alouini, Mohamed-Slim; Ooi, Boon S

2017-09-18

A demonstration of ultraviolet-B (UVB) communication link is implemented utilizing quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM). The demonstration is based on a 294-nm UVB-light-emitting-diode (UVB-LED) with a full-width at half-maximum (FWHM) of 9 nm and light output power of 190 μW, at 7 V, with a special silica gel lens on top of it. A -3-dB bandwidth of 29 MHz was measured and a high-speed near-solar-blind communication link with a data rate of 71 Mbit/s was achieved using 8-QAM-OFDM at perfect alignment. 23.6 Mbit/s using 2-QAM-OFDM when the angle subtended by the pointing directions of the UVB-LED and photodetector (PD) is 12 degrees, thus establishing a diffuse-line-of-sight (LOS) link. The measured bit-error rate (BER) of 2.8 ×10 -4 and 2.4 ×10 -4 , respectively, are well below the forward error correction (FEC) criterion of 3.8 ×10 -3 . The demonstrated high data-rate OFDM-based UVB communication link paves the way for realizing high-speed non-line-of-sight free-space optical communications.

Modeling and measurement of tissue elastic moduli using optical coherence elastography

NASA Astrophysics Data System (ADS)

Liang, Xing; Oldenburg, Amy L.; Crecea, Vasilica; Kalyanam, Sureshkumar; Insana, Michael F.; Boppart, Stephen A.

2008-02-01

Mechanical forces play crucial roles in tissue growth, patterning and development. To understand the role of mechanical stimuli, biomechanical properties are of great importance, as well as our ability to measure biomechanical properties of developing and engineered tissues. To enable these measurements, a novel non-invasive, micron-scale and high-speed Optical Coherence Elastography (OCE) system has been developed utilizing a titanium:sapphire based spectral-domain Optical Coherence Tomography (OCT) system and a mechanical wave driver. This system provides axial resolution of 3 microns, transverse resolution of 13 microns, and an acquisition rate as high as 25,000 lines per second. External lowfrequency vibrations are applied to the samples in the system. Step and sinusoidal steady-state responses are obtained to first characterize the OCE system and then characterize samples. Experimental results of M-mode OCE on silicone phantoms and human breast tissues are obtained, which correspond to biomechanical models developed for this analysis. Quantified results from the OCE system correspond directly with results from an indentation method from a commercial. With micron-scale resolution and a high-speed acquisition rate, our OCE system also has the potential to rapidly measure dynamic 3-D tissue biomechanical properties.

System-on-chip architecture and validation for real-time transceiver optimization: APC implementation on FPGA

NASA Astrophysics Data System (ADS)

Suarez, Hernan; Zhang, Yan R.

2015-05-01

New radar applications need to perform complex algorithms and process large quantity of data to generate useful information for the users. This situation has motivated the search for better processing solutions that include low power high-performance processors, efficient algorithms, and high-speed interfaces. In this work, hardware implementation of adaptive pulse compression for real-time transceiver optimization are presented, they are based on a System-on-Chip architecture for Xilinx devices. This study also evaluates the performance of dedicated coprocessor as hardware accelerator units to speed up and improve the computation of computing-intensive tasks such matrix multiplication and matrix inversion which are essential units to solve the covariance matrix. The tradeoffs between latency and hardware utilization are also presented. Moreover, the system architecture takes advantage of the embedded processor, which is interconnected with the logic resources through the high performance AXI buses, to perform floating-point operations, control the processing blocks, and communicate with external PC through a customized software interface. The overall system functionality is demonstrated and tested for real-time operations using a Ku-band tested together with a low-cost channel emulator for different types of waveforms.